Fix internal error and improve 'set debug infrun 1'/target wait kind trace
[deliverable/binutils-gdb.git] / gdb / doc / gdb.texinfo
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c906108c 1\input texinfo @c -*-texinfo-*-
42a4f53d 2@c Copyright (C) 1988-2019 Free Software Foundation, Inc.
c906108c 3@c
5d161b24 4@c %**start of header
c906108c
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5@c makeinfo ignores cmds prev to setfilename, so its arg cannot make use
6@c of @set vars. However, you can override filename with makeinfo -o.
7@setfilename gdb.info
8@c
43662968 9@c man begin INCLUDE
c906108c 10@include gdb-cfg.texi
43662968 11@c man end
c906108c 12@c
c906108c 13@settitle Debugging with @value{GDBN}
c906108c
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14@setchapternewpage odd
15@c %**end of header
16
17@iftex
18@c @smallbook
19@c @cropmarks
20@end iftex
21
22@finalout
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23@c To avoid file-name clashes between index.html and Index.html, when
24@c the manual is produced on a Posix host and then moved to a
25@c case-insensitive filesystem (e.g., MS-Windows), we separate the
26@c indices into two: Concept Index and all the rest.
27@syncodeindex ky fn
28@syncodeindex tp fn
c906108c 29
41afff9a 30@c readline appendices use @vindex, @findex and @ftable,
48e934c6 31@c annotate.texi and gdbmi use @findex.
00595b5e 32@syncodeindex vr fn
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33
34@c !!set GDB manual's edition---not the same as GDB version!
9fe8321b 35@c This is updated by GNU Press.
26829f2b 36@set EDITION Tenth
c906108c 37
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38@c !!set GDB edit command default editor
39@set EDITOR /bin/ex
c906108c 40
6c0e9fb3 41@c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER.
c906108c 42
c906108c 43@c This is a dir.info fragment to support semi-automated addition of
6d2ebf8b 44@c manuals to an info tree.
03727ca6 45@dircategory Software development
96a2c332 46@direntry
03727ca6 47* Gdb: (gdb). The GNU debugger.
6cb999f8 48* gdbserver: (gdb) Server. The GNU debugging server.
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49@end direntry
50
a67ec3f4 51@copying
43662968 52@c man begin COPYRIGHT
c97a7739 53Copyright @copyright{} 1988-2019 Free Software Foundation, Inc.
c906108c 54
e9c75b65 55Permission is granted to copy, distribute and/or modify this document
4f5d9f07 56under the terms of the GNU Free Documentation License, Version 1.3 or
e9c75b65 57any later version published by the Free Software Foundation; with the
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58Invariant Sections being ``Free Software'' and ``Free Software Needs
59Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
60and with the Back-Cover Texts as in (a) below.
c906108c 61
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62(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
63this GNU Manual. Buying copies from GNU Press supports the FSF in
64developing GNU and promoting software freedom.''
43662968 65@c man end
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66@end copying
67
68@ifnottex
69This file documents the @sc{gnu} debugger @value{GDBN}.
70
71This is the @value{EDITION} Edition, of @cite{Debugging with
72@value{GDBN}: the @sc{gnu} Source-Level Debugger} for @value{GDBN}
73@ifset VERSION_PACKAGE
74@value{VERSION_PACKAGE}
75@end ifset
76Version @value{GDBVN}.
77
78@insertcopying
79@end ifnottex
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80
81@titlepage
82@title Debugging with @value{GDBN}
83@subtitle The @sc{gnu} Source-Level Debugger
c906108c 84@sp 1
c906108c 85@subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN}
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86@ifset VERSION_PACKAGE
87@sp 1
88@subtitle @value{VERSION_PACKAGE}
89@end ifset
9e9c5ae7 90@author Richard Stallman, Roland Pesch, Stan Shebs, et al.
c906108c 91@page
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92@tex
93{\parskip=0pt
c16158bc 94\hfill (Send bugs and comments on @value{GDBN} to @value{BUGURL}.)\par
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95\hfill {\it Debugging with @value{GDBN}}\par
96\hfill \TeX{}info \texinfoversion\par
97}
98@end tex
53a5351d 99
c906108c 100@vskip 0pt plus 1filll
c906108c 101Published by the Free Software Foundation @*
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10251 Franklin Street, Fifth Floor,
103Boston, MA 02110-1301, USA@*
26829f2b 104ISBN 978-0-9831592-3-0 @*
e9c75b65 105
a67ec3f4 106@insertcopying
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107@end titlepage
108@page
109
6c0e9fb3 110@ifnottex
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111@node Top, Summary, (dir), (dir)
112
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113@top Debugging with @value{GDBN}
114
115This file describes @value{GDBN}, the @sc{gnu} symbolic debugger.
116
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117This is the @value{EDITION} Edition, for @value{GDBN}
118@ifset VERSION_PACKAGE
119@value{VERSION_PACKAGE}
120@end ifset
121Version @value{GDBVN}.
c906108c 122
c97a7739 123Copyright (C) 1988-2019 Free Software Foundation, Inc.
6d2ebf8b 124
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125This edition of the GDB manual is dedicated to the memory of Fred
126Fish. Fred was a long-standing contributor to GDB and to Free
127software in general. We will miss him.
128
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129@menu
130* Summary:: Summary of @value{GDBN}
131* Sample Session:: A sample @value{GDBN} session
132
133* Invocation:: Getting in and out of @value{GDBN}
134* Commands:: @value{GDBN} commands
135* Running:: Running programs under @value{GDBN}
136* Stopping:: Stopping and continuing
bacec72f 137* Reverse Execution:: Running programs backward
a2311334 138* Process Record and Replay:: Recording inferior's execution and replaying it
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139* Stack:: Examining the stack
140* Source:: Examining source files
141* Data:: Examining data
edb3359d 142* Optimized Code:: Debugging optimized code
e2e0bcd1 143* Macros:: Preprocessor Macros
b37052ae 144* Tracepoints:: Debugging remote targets non-intrusively
df0cd8c5 145* Overlays:: Debugging programs that use overlays
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146
147* Languages:: Using @value{GDBN} with different languages
148
149* Symbols:: Examining the symbol table
150* Altering:: Altering execution
151* GDB Files:: @value{GDBN} files
152* Targets:: Specifying a debugging target
6b2f586d 153* Remote Debugging:: Debugging remote programs
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154* Configurations:: Configuration-specific information
155* Controlling GDB:: Controlling @value{GDBN}
d57a3c85 156* Extending GDB:: Extending @value{GDBN}
21c294e6 157* Interpreters:: Command Interpreters
c8f4133a 158* TUI:: @value{GDBN} Text User Interface
6d2ebf8b 159* Emacs:: Using @value{GDBN} under @sc{gnu} Emacs
7162c0ca 160* GDB/MI:: @value{GDBN}'s Machine Interface.
c8f4133a 161* Annotations:: @value{GDBN}'s annotation interface.
4efc6507 162* JIT Interface:: Using the JIT debugging interface.
d1feda86 163* In-Process Agent:: In-Process Agent
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164
165* GDB Bugs:: Reporting bugs in @value{GDBN}
6d2ebf8b 166
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167@ifset SYSTEM_READLINE
168* Command Line Editing: (rluserman). Command Line Editing
169* Using History Interactively: (history). Using History Interactively
170@end ifset
171@ifclear SYSTEM_READLINE
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172* Command Line Editing:: Command Line Editing
173* Using History Interactively:: Using History Interactively
39037522 174@end ifclear
4ceed123 175* In Memoriam:: In Memoriam
0869d01b 176* Formatting Documentation:: How to format and print @value{GDBN} documentation
6d2ebf8b 177* Installing GDB:: Installing GDB
eb12ee30 178* Maintenance Commands:: Maintenance Commands
e0ce93ac 179* Remote Protocol:: GDB Remote Serial Protocol
f418dd93 180* Agent Expressions:: The GDB Agent Expression Mechanism
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181* Target Descriptions:: How targets can describe themselves to
182 @value{GDBN}
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183* Operating System Information:: Getting additional information from
184 the operating system
00bf0b85 185* Trace File Format:: GDB trace file format
90476074 186* Index Section Format:: .gdb_index section format
43662968 187* Man Pages:: Manual pages
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188* Copying:: GNU General Public License says
189 how you can copy and share GDB
6826cf00 190* GNU Free Documentation License:: The license for this documentation
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191* Concept Index:: Index of @value{GDBN} concepts
192* Command and Variable Index:: Index of @value{GDBN} commands, variables,
193 functions, and Python data types
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194@end menu
195
6c0e9fb3 196@end ifnottex
c906108c 197
449f3b6c 198@contents
449f3b6c 199
6d2ebf8b 200@node Summary
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201@unnumbered Summary of @value{GDBN}
202
203The purpose of a debugger such as @value{GDBN} is to allow you to see what is
204going on ``inside'' another program while it executes---or what another
205program was doing at the moment it crashed.
206
207@value{GDBN} can do four main kinds of things (plus other things in support of
208these) to help you catch bugs in the act:
209
210@itemize @bullet
211@item
212Start your program, specifying anything that might affect its behavior.
213
214@item
215Make your program stop on specified conditions.
216
217@item
218Examine what has happened, when your program has stopped.
219
220@item
221Change things in your program, so you can experiment with correcting the
222effects of one bug and go on to learn about another.
223@end itemize
224
49efadf5 225You can use @value{GDBN} to debug programs written in C and C@t{++}.
79a6e687 226For more information, see @ref{Supported Languages,,Supported Languages}.
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227For more information, see @ref{C,,C and C++}.
228
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229Support for D is partial. For information on D, see
230@ref{D,,D}.
231
cce74817 232@cindex Modula-2
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233Support for Modula-2 is partial. For information on Modula-2, see
234@ref{Modula-2,,Modula-2}.
c906108c 235
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236Support for OpenCL C is partial. For information on OpenCL C, see
237@ref{OpenCL C,,OpenCL C}.
238
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239@cindex Pascal
240Debugging Pascal programs which use sets, subranges, file variables, or
241nested functions does not currently work. @value{GDBN} does not support
242entering expressions, printing values, or similar features using Pascal
243syntax.
c906108c 244
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245@cindex Fortran
246@value{GDBN} can be used to debug programs written in Fortran, although
53a5351d 247it may be necessary to refer to some variables with a trailing
cce74817 248underscore.
c906108c 249
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250@value{GDBN} can be used to debug programs written in Objective-C,
251using either the Apple/NeXT or the GNU Objective-C runtime.
252
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253@menu
254* Free Software:: Freely redistributable software
984359d2 255* Free Documentation:: Free Software Needs Free Documentation
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256* Contributors:: Contributors to GDB
257@end menu
258
6d2ebf8b 259@node Free Software
79a6e687 260@unnumberedsec Free Software
c906108c 261
5d161b24 262@value{GDBN} is @dfn{free software}, protected by the @sc{gnu}
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263General Public License
264(GPL). The GPL gives you the freedom to copy or adapt a licensed
265program---but every person getting a copy also gets with it the
266freedom to modify that copy (which means that they must get access to
267the source code), and the freedom to distribute further copies.
268Typical software companies use copyrights to limit your freedoms; the
269Free Software Foundation uses the GPL to preserve these freedoms.
270
271Fundamentally, the General Public License is a license which says that
272you have these freedoms and that you cannot take these freedoms away
273from anyone else.
274
984359d2 275@node Free Documentation
2666264b 276@unnumberedsec Free Software Needs Free Documentation
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277
278The biggest deficiency in the free software community today is not in
279the software---it is the lack of good free documentation that we can
280include with the free software. Many of our most important
281programs do not come with free reference manuals and free introductory
282texts. Documentation is an essential part of any software package;
283when an important free software package does not come with a free
284manual and a free tutorial, that is a major gap. We have many such
285gaps today.
286
287Consider Perl, for instance. The tutorial manuals that people
288normally use are non-free. How did this come about? Because the
289authors of those manuals published them with restrictive terms---no
290copying, no modification, source files not available---which exclude
291them from the free software world.
292
293That wasn't the first time this sort of thing happened, and it was far
294from the last. Many times we have heard a GNU user eagerly describe a
295manual that he is writing, his intended contribution to the community,
296only to learn that he had ruined everything by signing a publication
297contract to make it non-free.
298
299Free documentation, like free software, is a matter of freedom, not
300price. The problem with the non-free manual is not that publishers
301charge a price for printed copies---that in itself is fine. (The Free
302Software Foundation sells printed copies of manuals, too.) The
303problem is the restrictions on the use of the manual. Free manuals
304are available in source code form, and give you permission to copy and
305modify. Non-free manuals do not allow this.
306
307The criteria of freedom for a free manual are roughly the same as for
308free software. Redistribution (including the normal kinds of
309commercial redistribution) must be permitted, so that the manual can
310accompany every copy of the program, both on-line and on paper.
311
312Permission for modification of the technical content is crucial too.
313When people modify the software, adding or changing features, if they
314are conscientious they will change the manual too---so they can
315provide accurate and clear documentation for the modified program. A
316manual that leaves you no choice but to write a new manual to document
317a changed version of the program is not really available to our
318community.
319
320Some kinds of limits on the way modification is handled are
321acceptable. For example, requirements to preserve the original
322author's copyright notice, the distribution terms, or the list of
323authors, are ok. It is also no problem to require modified versions
324to include notice that they were modified. Even entire sections that
325may not be deleted or changed are acceptable, as long as they deal
326with nontechnical topics (like this one). These kinds of restrictions
327are acceptable because they don't obstruct the community's normal use
328of the manual.
329
330However, it must be possible to modify all the @emph{technical}
331content of the manual, and then distribute the result in all the usual
332media, through all the usual channels. Otherwise, the restrictions
333obstruct the use of the manual, it is not free, and we need another
334manual to replace it.
335
336Please spread the word about this issue. Our community continues to
337lose manuals to proprietary publishing. If we spread the word that
338free software needs free reference manuals and free tutorials, perhaps
339the next person who wants to contribute by writing documentation will
340realize, before it is too late, that only free manuals contribute to
341the free software community.
342
343If you are writing documentation, please insist on publishing it under
344the GNU Free Documentation License or another free documentation
345license. Remember that this decision requires your approval---you
346don't have to let the publisher decide. Some commercial publishers
347will use a free license if you insist, but they will not propose the
348option; it is up to you to raise the issue and say firmly that this is
349what you want. If the publisher you are dealing with refuses, please
350try other publishers. If you're not sure whether a proposed license
42584a72 351is free, write to @email{licensing@@gnu.org}.
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352
353You can encourage commercial publishers to sell more free, copylefted
354manuals and tutorials by buying them, and particularly by buying
355copies from the publishers that paid for their writing or for major
356improvements. Meanwhile, try to avoid buying non-free documentation
357at all. Check the distribution terms of a manual before you buy it,
358and insist that whoever seeks your business must respect your freedom.
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359Check the history of the book, and try to reward the publishers that
360have paid or pay the authors to work on it.
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361
362The Free Software Foundation maintains a list of free documentation
363published by other publishers, at
364@url{http://www.fsf.org/doc/other-free-books.html}.
365
6d2ebf8b 366@node Contributors
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367@unnumberedsec Contributors to @value{GDBN}
368
369Richard Stallman was the original author of @value{GDBN}, and of many
370other @sc{gnu} programs. Many others have contributed to its
371development. This section attempts to credit major contributors. One
372of the virtues of free software is that everyone is free to contribute
373to it; with regret, we cannot actually acknowledge everyone here. The
374file @file{ChangeLog} in the @value{GDBN} distribution approximates a
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375blow-by-blow account.
376
377Changes much prior to version 2.0 are lost in the mists of time.
378
379@quotation
380@emph{Plea:} Additions to this section are particularly welcome. If you
381or your friends (or enemies, to be evenhanded) have been unfairly
382omitted from this list, we would like to add your names!
383@end quotation
384
385So that they may not regard their many labors as thankless, we
386particularly thank those who shepherded @value{GDBN} through major
387releases:
7ba3cf9c 388Andrew Cagney (releases 6.3, 6.2, 6.1, 6.0, 5.3, 5.2, 5.1 and 5.0);
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389Jim Blandy (release 4.18);
390Jason Molenda (release 4.17);
391Stan Shebs (release 4.14);
392Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9);
393Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4);
394John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9);
395Jim Kingdon (releases 3.5, 3.4, and 3.3);
396and Randy Smith (releases 3.2, 3.1, and 3.0).
397
398Richard Stallman, assisted at various times by Peter TerMaat, Chris
399Hanson, and Richard Mlynarik, handled releases through 2.8.
400
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401Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support
402in @value{GDBN}, with significant additional contributions from Per
403Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++}
404demangler. Early work on C@t{++} was by Peter TerMaat (who also did
405much general update work leading to release 3.0).
c906108c 406
b37052ae 407@value{GDBN} uses the BFD subroutine library to examine multiple
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408object-file formats; BFD was a joint project of David V.
409Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore.
410
411David Johnson wrote the original COFF support; Pace Willison did
412the original support for encapsulated COFF.
413
0179ffac 414Brent Benson of Harris Computer Systems contributed DWARF 2 support.
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415
416Adam de Boor and Bradley Davis contributed the ISI Optimum V support.
417Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS
418support.
419Jean-Daniel Fekete contributed Sun 386i support.
420Chris Hanson improved the HP9000 support.
421Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support.
422David Johnson contributed Encore Umax support.
423Jyrki Kuoppala contributed Altos 3068 support.
424Jeff Law contributed HP PA and SOM support.
425Keith Packard contributed NS32K support.
426Doug Rabson contributed Acorn Risc Machine support.
427Bob Rusk contributed Harris Nighthawk CX-UX support.
428Chris Smith contributed Convex support (and Fortran debugging).
429Jonathan Stone contributed Pyramid support.
430Michael Tiemann contributed SPARC support.
431Tim Tucker contributed support for the Gould NP1 and Gould Powernode.
432Pace Willison contributed Intel 386 support.
433Jay Vosburgh contributed Symmetry support.
a37295f9 434Marko Mlinar contributed OpenRISC 1000 support.
c906108c 435
1104b9e7 436Andreas Schwab contributed M68K @sc{gnu}/Linux support.
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437
438Rich Schaefer and Peter Schauer helped with support of SunOS shared
439libraries.
440
441Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree
442about several machine instruction sets.
443
444Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop
445remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM
446contributed remote debugging modules for the i960, VxWorks, A29K UDI,
447and RDI targets, respectively.
448
449Brian Fox is the author of the readline libraries providing
450command-line editing and command history.
451
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452Andrew Beers of SUNY Buffalo wrote the language-switching code, the
453Modula-2 support, and contributed the Languages chapter of this manual.
c906108c 454
5d161b24 455Fred Fish wrote most of the support for Unix System Vr4.
b37052ae 456He also enhanced the command-completion support to cover C@t{++} overloaded
c906108c 457symbols.
c906108c 458
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459Hitachi America (now Renesas America), Ltd. sponsored the support for
460H8/300, H8/500, and Super-H processors.
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461
462NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors.
463
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464Mitsubishi (now Renesas) sponsored the support for D10V, D30V, and M32R/D
465processors.
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466
467Toshiba sponsored the support for the TX39 Mips processor.
468
469Matsushita sponsored the support for the MN10200 and MN10300 processors.
470
96a2c332 471Fujitsu sponsored the support for SPARClite and FR30 processors.
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472
473Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware
474watchpoints.
475
476Michael Snyder added support for tracepoints.
477
478Stu Grossman wrote gdbserver.
479
480Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made
96a2c332 481nearly innumerable bug fixes and cleanups throughout @value{GDBN}.
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482
483The following people at the Hewlett-Packard Company contributed
484support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0
b37052ae 485(narrow mode), HP's implementation of kernel threads, HP's aC@t{++}
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486compiler, and the Text User Interface (nee Terminal User Interface):
487Ben Krepp, Richard Title, John Bishop, Susan Macchia, Kathy Mann,
488Satish Pai, India Paul, Steve Rehrauer, and Elena Zannoni. Kim Haase
489provided HP-specific information in this manual.
c906108c 490
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491DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project.
492Robert Hoehne made significant contributions to the DJGPP port.
493
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494Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its
495development since 1991. Cygnus engineers who have worked on @value{GDBN}
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496fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin
497Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim
498Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler,
499Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek
500Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In
501addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton,
502JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug
503Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff
504Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner,
505Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin
506Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela
507Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David
508Zuhn have made contributions both large and small.
c906108c 509
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510Andrew Cagney, Fernando Nasser, and Elena Zannoni, while working for
511Cygnus Solutions, implemented the original @sc{gdb/mi} interface.
512
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513Jim Blandy added support for preprocessor macros, while working for Red
514Hat.
c906108c 515
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516Andrew Cagney designed @value{GDBN}'s architecture vector. Many
517people including Andrew Cagney, Stephane Carrez, Randolph Chung, Nick
518Duffek, Richard Henderson, Mark Kettenis, Grace Sainsbury, Kei
519Sakamoto, Yoshinori Sato, Michael Snyder, Andreas Schwab, Jason
520Thorpe, Corinna Vinschen, Ulrich Weigand, and Elena Zannoni, helped
521with the migration of old architectures to this new framework.
522
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523Andrew Cagney completely re-designed and re-implemented @value{GDBN}'s
524unwinder framework, this consisting of a fresh new design featuring
525frame IDs, independent frame sniffers, and the sentinel frame. Mark
526Kettenis implemented the @sc{dwarf 2} unwinder, Jeff Johnston the
527libunwind unwinder, and Andrew Cagney the dummy, sentinel, tramp, and
db2e3e2e 528trad unwinders. The architecture-specific changes, each involving a
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529complete rewrite of the architecture's frame code, were carried out by
530Jim Blandy, Joel Brobecker, Kevin Buettner, Andrew Cagney, Stephane
531Carrez, Randolph Chung, Orjan Friberg, Richard Henderson, Daniel
532Jacobowitz, Jeff Johnston, Mark Kettenis, Theodore A. Roth, Kei
533Sakamoto, Yoshinori Sato, Michael Snyder, Corinna Vinschen, and Ulrich
534Weigand.
535
ca3bf3bd
DJ
536Christian Zankel, Ross Morley, Bob Wilson, and Maxim Grigoriev from
537Tensilica, Inc.@: contributed support for Xtensa processors. Others
538who have worked on the Xtensa port of @value{GDBN} in the past include
539Steve Tjiang, John Newlin, and Scott Foehner.
540
08be9d71
ME
541Michael Eager and staff of Xilinx, Inc., contributed support for the
542Xilinx MicroBlaze architecture.
543
387360da
JB
544Initial support for the FreeBSD/mips target and native configuration
545was developed by SRI International and the University of Cambridge
546Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
547("CTSRD"), as part of the DARPA CRASH research programme.
548
74792ff7
JB
549Initial support for the FreeBSD/riscv target and native configuration
550was developed by SRI International and the University of Cambridge
551Computer Laboratory (Department of Computer Science and Technology)
552under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the DARPA
553SSITH research programme.
554
a994fec4
FJ
555The original port to the OpenRISC 1000 is believed to be due to
556Alessandro Forin and Per Bothner. More recent ports have been the work
557of Jeremy Bennett, Franck Jullien, Stefan Wallentowitz and
558Stafford Horne.
559
6d2ebf8b 560@node Sample Session
c906108c
SS
561@chapter A Sample @value{GDBN} Session
562
563You can use this manual at your leisure to read all about @value{GDBN}.
564However, a handful of commands are enough to get started using the
565debugger. This chapter illustrates those commands.
566
567@iftex
568In this sample session, we emphasize user input like this: @b{input},
569to make it easier to pick out from the surrounding output.
570@end iftex
571
572@c FIXME: this example may not be appropriate for some configs, where
573@c FIXME...primary interest is in remote use.
574
575One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro
576processor) exhibits the following bug: sometimes, when we change its
577quote strings from the default, the commands used to capture one macro
578definition within another stop working. In the following short @code{m4}
579session, we define a macro @code{foo} which expands to @code{0000}; we
580then use the @code{m4} built-in @code{defn} to define @code{bar} as the
581same thing. However, when we change the open quote string to
582@code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same
583procedure fails to define a new synonym @code{baz}:
584
585@smallexample
586$ @b{cd gnu/m4}
587$ @b{./m4}
588@b{define(foo,0000)}
589
590@b{foo}
5910000
592@b{define(bar,defn(`foo'))}
593
594@b{bar}
5950000
596@b{changequote(<QUOTE>,<UNQUOTE>)}
597
598@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
599@b{baz}
c8aa23ab 600@b{Ctrl-d}
c906108c
SS
601m4: End of input: 0: fatal error: EOF in string
602@end smallexample
603
604@noindent
605Let us use @value{GDBN} to try to see what is going on.
606
c906108c
SS
607@smallexample
608$ @b{@value{GDBP} m4}
609@c FIXME: this falsifies the exact text played out, to permit smallbook
610@c FIXME... format to come out better.
611@value{GDBN} is free software and you are welcome to distribute copies
5d161b24 612 of it under certain conditions; type "show copying" to see
c906108c 613 the conditions.
5d161b24 614There is absolutely no warranty for @value{GDBN}; type "show warranty"
c906108c
SS
615 for details.
616
617@value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc...
618(@value{GDBP})
619@end smallexample
c906108c
SS
620
621@noindent
622@value{GDBN} reads only enough symbol data to know where to find the
623rest when needed; as a result, the first prompt comes up very quickly.
624We now tell @value{GDBN} to use a narrower display width than usual, so
625that examples fit in this manual.
626
627@smallexample
628(@value{GDBP}) @b{set width 70}
629@end smallexample
630
631@noindent
632We need to see how the @code{m4} built-in @code{changequote} works.
633Having looked at the source, we know the relevant subroutine is
634@code{m4_changequote}, so we set a breakpoint there with the @value{GDBN}
635@code{break} command.
636
637@smallexample
638(@value{GDBP}) @b{break m4_changequote}
639Breakpoint 1 at 0x62f4: file builtin.c, line 879.
640@end smallexample
641
642@noindent
643Using the @code{run} command, we start @code{m4} running under @value{GDBN}
644control; as long as control does not reach the @code{m4_changequote}
645subroutine, the program runs as usual:
646
647@smallexample
648(@value{GDBP}) @b{run}
649Starting program: /work/Editorial/gdb/gnu/m4/m4
650@b{define(foo,0000)}
651
652@b{foo}
6530000
654@end smallexample
655
656@noindent
657To trigger the breakpoint, we call @code{changequote}. @value{GDBN}
658suspends execution of @code{m4}, displaying information about the
659context where it stops.
660
661@smallexample
662@b{changequote(<QUOTE>,<UNQUOTE>)}
663
5d161b24 664Breakpoint 1, m4_changequote (argc=3, argv=0x33c70)
c906108c
SS
665 at builtin.c:879
666879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3))
667@end smallexample
668
669@noindent
670Now we use the command @code{n} (@code{next}) to advance execution to
671the next line of the current function.
672
673@smallexample
674(@value{GDBP}) @b{n}
675882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\
676 : nil,
677@end smallexample
678
679@noindent
680@code{set_quotes} looks like a promising subroutine. We can go into it
681by using the command @code{s} (@code{step}) instead of @code{next}.
682@code{step} goes to the next line to be executed in @emph{any}
683subroutine, so it steps into @code{set_quotes}.
684
685@smallexample
686(@value{GDBP}) @b{s}
687set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
688 at input.c:530
689530 if (lquote != def_lquote)
690@end smallexample
691
692@noindent
693The display that shows the subroutine where @code{m4} is now
694suspended (and its arguments) is called a stack frame display. It
695shows a summary of the stack. We can use the @code{backtrace}
696command (which can also be spelled @code{bt}), to see where we are
697in the stack as a whole: the @code{backtrace} command displays a
698stack frame for each active subroutine.
699
700@smallexample
701(@value{GDBP}) @b{bt}
702#0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
703 at input.c:530
5d161b24 704#1 0x6344 in m4_changequote (argc=3, argv=0x33c70)
c906108c
SS
705 at builtin.c:882
706#2 0x8174 in expand_macro (sym=0x33320) at macro.c:242
707#3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30)
708 at macro.c:71
709#4 0x79dc in expand_input () at macro.c:40
710#5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195
711@end smallexample
712
713@noindent
714We step through a few more lines to see what happens. The first two
715times, we can use @samp{s}; the next two times we use @code{n} to avoid
716falling into the @code{xstrdup} subroutine.
717
718@smallexample
719(@value{GDBP}) @b{s}
7200x3b5c 532 if (rquote != def_rquote)
721(@value{GDBP}) @b{s}
7220x3b80 535 lquote = (lq == nil || *lq == '\0') ? \
723def_lquote : xstrdup(lq);
724(@value{GDBP}) @b{n}
725536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
726 : xstrdup(rq);
727(@value{GDBP}) @b{n}
728538 len_lquote = strlen(rquote);
729@end smallexample
730
731@noindent
732The last line displayed looks a little odd; we can examine the variables
733@code{lquote} and @code{rquote} to see if they are in fact the new left
734and right quotes we specified. We use the command @code{p}
735(@code{print}) to see their values.
736
737@smallexample
738(@value{GDBP}) @b{p lquote}
739$1 = 0x35d40 "<QUOTE>"
740(@value{GDBP}) @b{p rquote}
741$2 = 0x35d50 "<UNQUOTE>"
742@end smallexample
743
744@noindent
745@code{lquote} and @code{rquote} are indeed the new left and right quotes.
746To look at some context, we can display ten lines of source
747surrounding the current line with the @code{l} (@code{list}) command.
748
749@smallexample
750(@value{GDBP}) @b{l}
751533 xfree(rquote);
752534
753535 lquote = (lq == nil || *lq == '\0') ? def_lquote\
754 : xstrdup (lq);
755536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
756 : xstrdup (rq);
757537
758538 len_lquote = strlen(rquote);
759539 len_rquote = strlen(lquote);
760540 @}
761541
762542 void
763@end smallexample
764
765@noindent
766Let us step past the two lines that set @code{len_lquote} and
767@code{len_rquote}, and then examine the values of those variables.
768
769@smallexample
770(@value{GDBP}) @b{n}
771539 len_rquote = strlen(lquote);
772(@value{GDBP}) @b{n}
773540 @}
774(@value{GDBP}) @b{p len_lquote}
775$3 = 9
776(@value{GDBP}) @b{p len_rquote}
777$4 = 7
778@end smallexample
779
780@noindent
781That certainly looks wrong, assuming @code{len_lquote} and
782@code{len_rquote} are meant to be the lengths of @code{lquote} and
783@code{rquote} respectively. We can set them to better values using
784the @code{p} command, since it can print the value of
785any expression---and that expression can include subroutine calls and
786assignments.
787
788@smallexample
789(@value{GDBP}) @b{p len_lquote=strlen(lquote)}
790$5 = 7
791(@value{GDBP}) @b{p len_rquote=strlen(rquote)}
792$6 = 9
793@end smallexample
794
795@noindent
796Is that enough to fix the problem of using the new quotes with the
797@code{m4} built-in @code{defn}? We can allow @code{m4} to continue
798executing with the @code{c} (@code{continue}) command, and then try the
799example that caused trouble initially:
800
801@smallexample
802(@value{GDBP}) @b{c}
803Continuing.
804
805@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
806
807baz
8080000
809@end smallexample
810
811@noindent
812Success! The new quotes now work just as well as the default ones. The
813problem seems to have been just the two typos defining the wrong
814lengths. We allow @code{m4} exit by giving it an EOF as input:
815
816@smallexample
c8aa23ab 817@b{Ctrl-d}
c906108c
SS
818Program exited normally.
819@end smallexample
820
821@noindent
822The message @samp{Program exited normally.} is from @value{GDBN}; it
823indicates @code{m4} has finished executing. We can end our @value{GDBN}
824session with the @value{GDBN} @code{quit} command.
825
826@smallexample
827(@value{GDBP}) @b{quit}
828@end smallexample
c906108c 829
6d2ebf8b 830@node Invocation
c906108c
SS
831@chapter Getting In and Out of @value{GDBN}
832
833This chapter discusses how to start @value{GDBN}, and how to get out of it.
5d161b24 834The essentials are:
c906108c 835@itemize @bullet
5d161b24 836@item
53a5351d 837type @samp{@value{GDBP}} to start @value{GDBN}.
5d161b24 838@item
c8aa23ab 839type @kbd{quit} or @kbd{Ctrl-d} to exit.
c906108c
SS
840@end itemize
841
842@menu
843* Invoking GDB:: How to start @value{GDBN}
844* Quitting GDB:: How to quit @value{GDBN}
845* Shell Commands:: How to use shell commands inside @value{GDBN}
79a6e687 846* Logging Output:: How to log @value{GDBN}'s output to a file
c906108c
SS
847@end menu
848
6d2ebf8b 849@node Invoking GDB
c906108c
SS
850@section Invoking @value{GDBN}
851
c906108c
SS
852Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started,
853@value{GDBN} reads commands from the terminal until you tell it to exit.
854
855You can also run @code{@value{GDBP}} with a variety of arguments and options,
856to specify more of your debugging environment at the outset.
857
c906108c
SS
858The command-line options described here are designed
859to cover a variety of situations; in some environments, some of these
5d161b24 860options may effectively be unavailable.
c906108c
SS
861
862The most usual way to start @value{GDBN} is with one argument,
863specifying an executable program:
864
474c8240 865@smallexample
c906108c 866@value{GDBP} @var{program}
474c8240 867@end smallexample
c906108c 868
c906108c
SS
869@noindent
870You can also start with both an executable program and a core file
871specified:
872
474c8240 873@smallexample
c906108c 874@value{GDBP} @var{program} @var{core}
474c8240 875@end smallexample
c906108c
SS
876
877You can, instead, specify a process ID as a second argument, if you want
878to debug a running process:
879
474c8240 880@smallexample
c906108c 881@value{GDBP} @var{program} 1234
474c8240 882@end smallexample
c906108c
SS
883
884@noindent
885would attach @value{GDBN} to process @code{1234} (unless you also have a file
886named @file{1234}; @value{GDBN} does check for a core file first).
887
c906108c 888Taking advantage of the second command-line argument requires a fairly
2df3850c
JM
889complete operating system; when you use @value{GDBN} as a remote
890debugger attached to a bare board, there may not be any notion of
891``process'', and there is often no way to get a core dump. @value{GDBN}
892will warn you if it is unable to attach or to read core dumps.
c906108c 893
aa26fa3a
TT
894You can optionally have @code{@value{GDBP}} pass any arguments after the
895executable file to the inferior using @code{--args}. This option stops
896option processing.
474c8240 897@smallexample
3f94c067 898@value{GDBP} --args gcc -O2 -c foo.c
474c8240 899@end smallexample
aa26fa3a
TT
900This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set
901@code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}.
902
96a2c332 903You can run @code{@value{GDBP}} without printing the front material, which describes
adcc0a31 904@value{GDBN}'s non-warranty, by specifying @code{--silent}
905(or @code{-q}/@code{--quiet}):
c906108c
SS
906
907@smallexample
adcc0a31 908@value{GDBP} --silent
c906108c
SS
909@end smallexample
910
911@noindent
912You can further control how @value{GDBN} starts up by using command-line
913options. @value{GDBN} itself can remind you of the options available.
914
915@noindent
916Type
917
474c8240 918@smallexample
c906108c 919@value{GDBP} -help
474c8240 920@end smallexample
c906108c
SS
921
922@noindent
923to display all available options and briefly describe their use
924(@samp{@value{GDBP} -h} is a shorter equivalent).
925
926All options and command line arguments you give are processed
927in sequential order. The order makes a difference when the
928@samp{-x} option is used.
929
930
931@menu
c906108c
SS
932* File Options:: Choosing files
933* Mode Options:: Choosing modes
6fc08d32 934* Startup:: What @value{GDBN} does during startup
c906108c
SS
935@end menu
936
6d2ebf8b 937@node File Options
79a6e687 938@subsection Choosing Files
c906108c 939
2df3850c 940When @value{GDBN} starts, it reads any arguments other than options as
c906108c
SS
941specifying an executable file and core file (or process ID). This is
942the same as if the arguments were specified by the @samp{-se} and
d52fb0e9 943@samp{-c} (or @samp{-p}) options respectively. (@value{GDBN} reads the
19837790
MS
944first argument that does not have an associated option flag as
945equivalent to the @samp{-se} option followed by that argument; and the
946second argument that does not have an associated option flag, if any, as
947equivalent to the @samp{-c}/@samp{-p} option followed by that argument.)
948If the second argument begins with a decimal digit, @value{GDBN} will
949first attempt to attach to it as a process, and if that fails, attempt
950to open it as a corefile. If you have a corefile whose name begins with
b383017d 951a digit, you can prevent @value{GDBN} from treating it as a pid by
c1468174 952prefixing it with @file{./}, e.g.@: @file{./12345}.
7a292a7a
SS
953
954If @value{GDBN} has not been configured to included core file support,
955such as for most embedded targets, then it will complain about a second
956argument and ignore it.
c906108c
SS
957
958Many options have both long and short forms; both are shown in the
959following list. @value{GDBN} also recognizes the long forms if you truncate
960them, so long as enough of the option is present to be unambiguous.
961(If you prefer, you can flag option arguments with @samp{--} rather
962than @samp{-}, though we illustrate the more usual convention.)
963
d700128c
EZ
964@c NOTE: the @cindex entries here use double dashes ON PURPOSE. This
965@c way, both those who look for -foo and --foo in the index, will find
966@c it.
967
c906108c
SS
968@table @code
969@item -symbols @var{file}
970@itemx -s @var{file}
d700128c
EZ
971@cindex @code{--symbols}
972@cindex @code{-s}
c906108c
SS
973Read symbol table from file @var{file}.
974
975@item -exec @var{file}
976@itemx -e @var{file}
d700128c
EZ
977@cindex @code{--exec}
978@cindex @code{-e}
7a292a7a
SS
979Use file @var{file} as the executable file to execute when appropriate,
980and for examining pure data in conjunction with a core dump.
c906108c
SS
981
982@item -se @var{file}
d700128c 983@cindex @code{--se}
c906108c
SS
984Read symbol table from file @var{file} and use it as the executable
985file.
986
c906108c
SS
987@item -core @var{file}
988@itemx -c @var{file}
d700128c
EZ
989@cindex @code{--core}
990@cindex @code{-c}
b383017d 991Use file @var{file} as a core dump to examine.
c906108c 992
19837790
MS
993@item -pid @var{number}
994@itemx -p @var{number}
995@cindex @code{--pid}
996@cindex @code{-p}
997Connect to process ID @var{number}, as with the @code{attach} command.
c906108c
SS
998
999@item -command @var{file}
1000@itemx -x @var{file}
d700128c
EZ
1001@cindex @code{--command}
1002@cindex @code{-x}
95433b34
JB
1003Execute commands from file @var{file}. The contents of this file is
1004evaluated exactly as the @code{source} command would.
8150ff9c 1005@xref{Command Files,, Command files}.
c906108c 1006
8a5a3c82
AS
1007@item -eval-command @var{command}
1008@itemx -ex @var{command}
1009@cindex @code{--eval-command}
1010@cindex @code{-ex}
1011Execute a single @value{GDBN} command.
1012
1013This option may be used multiple times to call multiple commands. It may
1014also be interleaved with @samp{-command} as required.
1015
1016@smallexample
1017@value{GDBP} -ex 'target sim' -ex 'load' \
1018 -x setbreakpoints -ex 'run' a.out
1019@end smallexample
1020
8320cc4f
JK
1021@item -init-command @var{file}
1022@itemx -ix @var{file}
1023@cindex @code{--init-command}
1024@cindex @code{-ix}
2d7b58e8
JK
1025Execute commands from file @var{file} before loading the inferior (but
1026after loading gdbinit files).
8320cc4f
JK
1027@xref{Startup}.
1028
1029@item -init-eval-command @var{command}
1030@itemx -iex @var{command}
1031@cindex @code{--init-eval-command}
1032@cindex @code{-iex}
2d7b58e8
JK
1033Execute a single @value{GDBN} command before loading the inferior (but
1034after loading gdbinit files).
8320cc4f
JK
1035@xref{Startup}.
1036
c906108c
SS
1037@item -directory @var{directory}
1038@itemx -d @var{directory}
d700128c
EZ
1039@cindex @code{--directory}
1040@cindex @code{-d}
4b505b12 1041Add @var{directory} to the path to search for source and script files.
c906108c 1042
c906108c
SS
1043@item -r
1044@itemx -readnow
d700128c
EZ
1045@cindex @code{--readnow}
1046@cindex @code{-r}
c906108c
SS
1047Read each symbol file's entire symbol table immediately, rather than
1048the default, which is to read it incrementally as it is needed.
1049This makes startup slower, but makes future operations faster.
53a5351d 1050
97cbe998
SDJ
1051@item --readnever
1052@anchor{--readnever}
1053@cindex @code{--readnever}, command-line option
1054Do not read each symbol file's symbolic debug information. This makes
1055startup faster but at the expense of not being able to perform
1056symbolic debugging. DWARF unwind information is also not read,
1057meaning backtraces may become incomplete or inaccurate. One use of
1058this is when a user simply wants to do the following sequence: attach,
1059dump core, detach. Loading the debugging information in this case is
1060an unnecessary cause of delay.
c906108c
SS
1061@end table
1062
6d2ebf8b 1063@node Mode Options
79a6e687 1064@subsection Choosing Modes
c906108c
SS
1065
1066You can run @value{GDBN} in various alternative modes---for example, in
1067batch mode or quiet mode.
1068
1069@table @code
bf88dd68 1070@anchor{-nx}
c906108c
SS
1071@item -nx
1072@itemx -n
d700128c
EZ
1073@cindex @code{--nx}
1074@cindex @code{-n}
07540c15
DE
1075Do not execute commands found in any initialization file.
1076There are three init files, loaded in the following order:
1077
1078@table @code
1079@item @file{system.gdbinit}
1080This is the system-wide init file.
1081Its location is specified with the @code{--with-system-gdbinit}
1082configure option (@pxref{System-wide configuration}).
1083It is loaded first when @value{GDBN} starts, before command line options
1084have been processed.
1085@item @file{~/.gdbinit}
1086This is the init file in your home directory.
1087It is loaded next, after @file{system.gdbinit}, and before
1088command options have been processed.
1089@item @file{./.gdbinit}
1090This is the init file in the current directory.
1091It is loaded last, after command line options other than @code{-x} and
1092@code{-ex} have been processed. Command line options @code{-x} and
1093@code{-ex} are processed last, after @file{./.gdbinit} has been loaded.
1094@end table
1095
1096For further documentation on startup processing, @xref{Startup}.
1097For documentation on how to write command files,
1098@xref{Command Files,,Command Files}.
1099
1100@anchor{-nh}
1101@item -nh
1102@cindex @code{--nh}
1103Do not execute commands found in @file{~/.gdbinit}, the init file
1104in your home directory.
1105@xref{Startup}.
c906108c
SS
1106
1107@item -quiet
d700128c 1108@itemx -silent
c906108c 1109@itemx -q
d700128c
EZ
1110@cindex @code{--quiet}
1111@cindex @code{--silent}
1112@cindex @code{-q}
c906108c
SS
1113``Quiet''. Do not print the introductory and copyright messages. These
1114messages are also suppressed in batch mode.
1115
1116@item -batch
d700128c 1117@cindex @code{--batch}
c906108c
SS
1118Run in batch mode. Exit with status @code{0} after processing all the
1119command files specified with @samp{-x} (and all commands from
1120initialization files, if not inhibited with @samp{-n}). Exit with
1121nonzero status if an error occurs in executing the @value{GDBN} commands
5da1313b
JK
1122in the command files. Batch mode also disables pagination, sets unlimited
1123terminal width and height @pxref{Screen Size}, and acts as if @kbd{set confirm
1124off} were in effect (@pxref{Messages/Warnings}).
c906108c 1125
2df3850c
JM
1126Batch mode may be useful for running @value{GDBN} as a filter, for
1127example to download and run a program on another computer; in order to
1128make this more useful, the message
c906108c 1129
474c8240 1130@smallexample
c906108c 1131Program exited normally.
474c8240 1132@end smallexample
c906108c
SS
1133
1134@noindent
2df3850c
JM
1135(which is ordinarily issued whenever a program running under
1136@value{GDBN} control terminates) is not issued when running in batch
1137mode.
1138
1a088d06
AS
1139@item -batch-silent
1140@cindex @code{--batch-silent}
1141Run in batch mode exactly like @samp{-batch}, but totally silently. All
1142@value{GDBN} output to @code{stdout} is prevented (@code{stderr} is
1143unaffected). This is much quieter than @samp{-silent} and would be useless
1144for an interactive session.
1145
1146This is particularly useful when using targets that give @samp{Loading section}
1147messages, for example.
1148
1149Note that targets that give their output via @value{GDBN}, as opposed to
1150writing directly to @code{stdout}, will also be made silent.
1151
4b0ad762
AS
1152@item -return-child-result
1153@cindex @code{--return-child-result}
1154The return code from @value{GDBN} will be the return code from the child
1155process (the process being debugged), with the following exceptions:
1156
1157@itemize @bullet
1158@item
1159@value{GDBN} exits abnormally. E.g., due to an incorrect argument or an
1160internal error. In this case the exit code is the same as it would have been
1161without @samp{-return-child-result}.
1162@item
1163The user quits with an explicit value. E.g., @samp{quit 1}.
1164@item
1165The child process never runs, or is not allowed to terminate, in which case
1166the exit code will be -1.
1167@end itemize
1168
1169This option is useful in conjunction with @samp{-batch} or @samp{-batch-silent},
1170when @value{GDBN} is being used as a remote program loader or simulator
1171interface.
1172
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JM
1173@item -nowindows
1174@itemx -nw
d700128c
EZ
1175@cindex @code{--nowindows}
1176@cindex @code{-nw}
2df3850c 1177``No windows''. If @value{GDBN} comes with a graphical user interface
96a2c332 1178(GUI) built in, then this option tells @value{GDBN} to only use the command-line
2df3850c
JM
1179interface. If no GUI is available, this option has no effect.
1180
1181@item -windows
1182@itemx -w
d700128c
EZ
1183@cindex @code{--windows}
1184@cindex @code{-w}
2df3850c
JM
1185If @value{GDBN} includes a GUI, then this option requires it to be
1186used if possible.
c906108c
SS
1187
1188@item -cd @var{directory}
d700128c 1189@cindex @code{--cd}
c906108c
SS
1190Run @value{GDBN} using @var{directory} as its working directory,
1191instead of the current directory.
1192
aae1c79a 1193@item -data-directory @var{directory}
8d551b02 1194@itemx -D @var{directory}
aae1c79a 1195@cindex @code{--data-directory}
8d551b02 1196@cindex @code{-D}
aae1c79a
DE
1197Run @value{GDBN} using @var{directory} as its data directory.
1198The data directory is where @value{GDBN} searches for its
1199auxiliary files. @xref{Data Files}.
1200
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SS
1201@item -fullname
1202@itemx -f
d700128c
EZ
1203@cindex @code{--fullname}
1204@cindex @code{-f}
7a292a7a
SS
1205@sc{gnu} Emacs sets this option when it runs @value{GDBN} as a
1206subprocess. It tells @value{GDBN} to output the full file name and line
1207number in a standard, recognizable fashion each time a stack frame is
1208displayed (which includes each time your program stops). This
1209recognizable format looks like two @samp{\032} characters, followed by
1210the file name, line number and character position separated by colons,
1211and a newline. The Emacs-to-@value{GDBN} interface program uses the two
1212@samp{\032} characters as a signal to display the source code for the
1213frame.
c906108c 1214
d700128c
EZ
1215@item -annotate @var{level}
1216@cindex @code{--annotate}
1217This option sets the @dfn{annotation level} inside @value{GDBN}. Its
1218effect is identical to using @samp{set annotate @var{level}}
086432e2
AC
1219(@pxref{Annotations}). The annotation @var{level} controls how much
1220information @value{GDBN} prints together with its prompt, values of
1221expressions, source lines, and other types of output. Level 0 is the
1222normal, level 1 is for use when @value{GDBN} is run as a subprocess of
1223@sc{gnu} Emacs, level 3 is the maximum annotation suitable for programs
1224that control @value{GDBN}, and level 2 has been deprecated.
1225
265eeb58 1226The annotation mechanism has largely been superseded by @sc{gdb/mi}
086432e2 1227(@pxref{GDB/MI}).
d700128c 1228
aa26fa3a
TT
1229@item --args
1230@cindex @code{--args}
1231Change interpretation of command line so that arguments following the
1232executable file are passed as command line arguments to the inferior.
1233This option stops option processing.
1234
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JM
1235@item -baud @var{bps}
1236@itemx -b @var{bps}
d700128c
EZ
1237@cindex @code{--baud}
1238@cindex @code{-b}
c906108c
SS
1239Set the line speed (baud rate or bits per second) of any serial
1240interface used by @value{GDBN} for remote debugging.
c906108c 1241
f47b1503
AS
1242@item -l @var{timeout}
1243@cindex @code{-l}
1244Set the timeout (in seconds) of any communication used by @value{GDBN}
1245for remote debugging.
1246
c906108c 1247@item -tty @var{device}
d700128c
EZ
1248@itemx -t @var{device}
1249@cindex @code{--tty}
1250@cindex @code{-t}
c906108c
SS
1251Run using @var{device} for your program's standard input and output.
1252@c FIXME: kingdon thinks there is more to -tty. Investigate.
c906108c 1253
53a5351d 1254@c resolve the situation of these eventually
c4555f82
SC
1255@item -tui
1256@cindex @code{--tui}
d0d5df6f
AC
1257Activate the @dfn{Text User Interface} when starting. The Text User
1258Interface manages several text windows on the terminal, showing
1259source, assembly, registers and @value{GDBN} command outputs
217bff3e
JK
1260(@pxref{TUI, ,@value{GDBN} Text User Interface}). Do not use this
1261option if you run @value{GDBN} from Emacs (@pxref{Emacs, ,
1262Using @value{GDBN} under @sc{gnu} Emacs}).
53a5351d 1263
d700128c
EZ
1264@item -interpreter @var{interp}
1265@cindex @code{--interpreter}
1266Use the interpreter @var{interp} for interface with the controlling
1267program or device. This option is meant to be set by programs which
94bbb2c0 1268communicate with @value{GDBN} using it as a back end.
21c294e6 1269@xref{Interpreters, , Command Interpreters}.
94bbb2c0 1270
b4be1b06
SM
1271@samp{--interpreter=mi} (or @samp{--interpreter=mi3}) causes
1272@value{GDBN} to use the @dfn{@sc{gdb/mi} interface} version 3 (@pxref{GDB/MI, ,
1273The @sc{gdb/mi} Interface}) included since @value{GDBN} version 9.1. @sc{gdb/mi}
1274version 2 (@code{mi2}), included in @value{GDBN} 6.0 and version 1 (@code{mi1}),
1275included in @value{GDBN} 5.3, are also available. Earlier @sc{gdb/mi}
1276interfaces are no longer supported.
d700128c
EZ
1277
1278@item -write
1279@cindex @code{--write}
1280Open the executable and core files for both reading and writing. This
1281is equivalent to the @samp{set write on} command inside @value{GDBN}
1282(@pxref{Patching}).
1283
1284@item -statistics
1285@cindex @code{--statistics}
1286This option causes @value{GDBN} to print statistics about time and
1287memory usage after it completes each command and returns to the prompt.
1288
1289@item -version
1290@cindex @code{--version}
1291This option causes @value{GDBN} to print its version number and
1292no-warranty blurb, and exit.
1293
6eaaf48b
EZ
1294@item -configuration
1295@cindex @code{--configuration}
1296This option causes @value{GDBN} to print details about its build-time
1297configuration parameters, and then exit. These details can be
1298important when reporting @value{GDBN} bugs (@pxref{GDB Bugs}).
1299
c906108c
SS
1300@end table
1301
6fc08d32 1302@node Startup
79a6e687 1303@subsection What @value{GDBN} Does During Startup
6fc08d32
EZ
1304@cindex @value{GDBN} startup
1305
1306Here's the description of what @value{GDBN} does during session startup:
1307
1308@enumerate
1309@item
1310Sets up the command interpreter as specified by the command line
1311(@pxref{Mode Options, interpreter}).
1312
1313@item
1314@cindex init file
098b41a6
JG
1315Reads the system-wide @dfn{init file} (if @option{--with-system-gdbinit} was
1316used when building @value{GDBN}; @pxref{System-wide configuration,
1317 ,System-wide configuration and settings}) and executes all the commands in
1318that file.
1319
bf88dd68 1320@anchor{Home Directory Init File}
098b41a6
JG
1321@item
1322Reads the init file (if any) in your home directory@footnote{On
6fc08d32
EZ
1323DOS/Windows systems, the home directory is the one pointed to by the
1324@code{HOME} environment variable.} and executes all the commands in
1325that file.
1326
2d7b58e8
JK
1327@anchor{Option -init-eval-command}
1328@item
1329Executes commands and command files specified by the @samp{-iex} and
1330@samp{-ix} options in their specified order. Usually you should use the
1331@samp{-ex} and @samp{-x} options instead, but this way you can apply
1332settings before @value{GDBN} init files get executed and before inferior
1333gets loaded.
1334
6fc08d32
EZ
1335@item
1336Processes command line options and operands.
1337
bf88dd68 1338@anchor{Init File in the Current Directory during Startup}
6fc08d32
EZ
1339@item
1340Reads and executes the commands from init file (if any) in the current
bf88dd68
JK
1341working directory as long as @samp{set auto-load local-gdbinit} is set to
1342@samp{on} (@pxref{Init File in the Current Directory}).
1343This is only done if the current directory is
119b882a
EZ
1344different from your home directory. Thus, you can have more than one
1345init file, one generic in your home directory, and another, specific
1346to the program you are debugging, in the directory where you invoke
6fc08d32
EZ
1347@value{GDBN}.
1348
a86caf66
DE
1349@item
1350If the command line specified a program to debug, or a process to
1351attach to, or a core file, @value{GDBN} loads any auto-loaded
1352scripts provided for the program or for its loaded shared libraries.
1353@xref{Auto-loading}.
1354
1355If you wish to disable the auto-loading during startup,
1356you must do something like the following:
1357
1358@smallexample
bf88dd68 1359$ gdb -iex "set auto-load python-scripts off" myprogram
a86caf66
DE
1360@end smallexample
1361
8320cc4f
JK
1362Option @samp{-ex} does not work because the auto-loading is then turned
1363off too late.
a86caf66 1364
6fc08d32 1365@item
6fe37d23
JK
1366Executes commands and command files specified by the @samp{-ex} and
1367@samp{-x} options in their specified order. @xref{Command Files}, for
1368more details about @value{GDBN} command files.
6fc08d32
EZ
1369
1370@item
1371Reads the command history recorded in the @dfn{history file}.
d620b259 1372@xref{Command History}, for more details about the command history and the
6fc08d32
EZ
1373files where @value{GDBN} records it.
1374@end enumerate
1375
1376Init files use the same syntax as @dfn{command files} (@pxref{Command
1377Files}) and are processed by @value{GDBN} in the same way. The init
1378file in your home directory can set options (such as @samp{set
1379complaints}) that affect subsequent processing of command line options
1380and operands. Init files are not executed if you use the @samp{-nx}
79a6e687 1381option (@pxref{Mode Options, ,Choosing Modes}).
6fc08d32 1382
098b41a6
JG
1383To display the list of init files loaded by gdb at startup, you
1384can use @kbd{gdb --help}.
1385
6fc08d32
EZ
1386@cindex init file name
1387@cindex @file{.gdbinit}
119b882a 1388@cindex @file{gdb.ini}
8807d78b 1389The @value{GDBN} init files are normally called @file{.gdbinit}.
119b882a
EZ
1390The DJGPP port of @value{GDBN} uses the name @file{gdb.ini}, due to
1391the limitations of file names imposed by DOS filesystems. The Windows
4d3f93a2
JB
1392port of @value{GDBN} uses the standard name, but if it finds a
1393@file{gdb.ini} file in your home directory, it warns you about that
1394and suggests to rename the file to the standard name.
119b882a 1395
6fc08d32 1396
6d2ebf8b 1397@node Quitting GDB
c906108c
SS
1398@section Quitting @value{GDBN}
1399@cindex exiting @value{GDBN}
1400@cindex leaving @value{GDBN}
1401
1402@table @code
1403@kindex quit @r{[}@var{expression}@r{]}
41afff9a 1404@kindex q @r{(@code{quit})}
96a2c332
SS
1405@item quit @r{[}@var{expression}@r{]}
1406@itemx q
1407To exit @value{GDBN}, use the @code{quit} command (abbreviated
c8aa23ab 1408@code{q}), or type an end-of-file character (usually @kbd{Ctrl-d}). If you
96a2c332
SS
1409do not supply @var{expression}, @value{GDBN} will terminate normally;
1410otherwise it will terminate using the result of @var{expression} as the
1411error code.
c906108c
SS
1412@end table
1413
1414@cindex interrupt
c8aa23ab 1415An interrupt (often @kbd{Ctrl-c}) does not exit from @value{GDBN}, but rather
c906108c
SS
1416terminates the action of any @value{GDBN} command that is in progress and
1417returns to @value{GDBN} command level. It is safe to type the interrupt
1418character at any time because @value{GDBN} does not allow it to take effect
1419until a time when it is safe.
1420
c906108c
SS
1421If you have been using @value{GDBN} to control an attached process or
1422device, you can release it with the @code{detach} command
79a6e687 1423(@pxref{Attach, ,Debugging an Already-running Process}).
c906108c 1424
6d2ebf8b 1425@node Shell Commands
79a6e687 1426@section Shell Commands
c906108c
SS
1427
1428If you need to execute occasional shell commands during your
1429debugging session, there is no need to leave or suspend @value{GDBN}; you can
1430just use the @code{shell} command.
1431
1432@table @code
1433@kindex shell
ed59ded5 1434@kindex !
c906108c 1435@cindex shell escape
ed59ded5
DE
1436@item shell @var{command-string}
1437@itemx !@var{command-string}
1438Invoke a standard shell to execute @var{command-string}.
1439Note that no space is needed between @code{!} and @var{command-string}.
c906108c 1440If it exists, the environment variable @code{SHELL} determines which
d4f3574e
SS
1441shell to run. Otherwise @value{GDBN} uses the default shell
1442(@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.).
c906108c
SS
1443@end table
1444
1445The utility @code{make} is often needed in development environments.
1446You do not have to use the @code{shell} command for this purpose in
1447@value{GDBN}:
1448
1449@table @code
1450@kindex make
1451@cindex calling make
1452@item make @var{make-args}
1453Execute the @code{make} program with the specified
1454arguments. This is equivalent to @samp{shell make @var{make-args}}.
1455@end table
1456
79a6e687
BW
1457@node Logging Output
1458@section Logging Output
0fac0b41 1459@cindex logging @value{GDBN} output
9c16f35a 1460@cindex save @value{GDBN} output to a file
0fac0b41
DJ
1461
1462You may want to save the output of @value{GDBN} commands to a file.
1463There are several commands to control @value{GDBN}'s logging.
1464
1465@table @code
1466@kindex set logging
1467@item set logging on
1468Enable logging.
1469@item set logging off
1470Disable logging.
9c16f35a 1471@cindex logging file name
0fac0b41
DJ
1472@item set logging file @var{file}
1473Change the name of the current logfile. The default logfile is @file{gdb.txt}.
1474@item set logging overwrite [on|off]
1475By default, @value{GDBN} will append to the logfile. Set @code{overwrite} if
1476you want @code{set logging on} to overwrite the logfile instead.
1477@item set logging redirect [on|off]
1478By default, @value{GDBN} output will go to both the terminal and the logfile.
1479Set @code{redirect} if you want output to go only to the log file.
1480@kindex show logging
1481@item show logging
1482Show the current values of the logging settings.
1483@end table
1484
6d2ebf8b 1485@node Commands
c906108c
SS
1486@chapter @value{GDBN} Commands
1487
1488You can abbreviate a @value{GDBN} command to the first few letters of the command
1489name, if that abbreviation is unambiguous; and you can repeat certain
1490@value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB}
1491key to get @value{GDBN} to fill out the rest of a word in a command (or to
1492show you the alternatives available, if there is more than one possibility).
1493
1494@menu
1495* Command Syntax:: How to give commands to @value{GDBN}
1496* Completion:: Command completion
1497* Help:: How to ask @value{GDBN} for help
1498@end menu
1499
6d2ebf8b 1500@node Command Syntax
79a6e687 1501@section Command Syntax
c906108c
SS
1502
1503A @value{GDBN} command is a single line of input. There is no limit on
1504how long it can be. It starts with a command name, which is followed by
1505arguments whose meaning depends on the command name. For example, the
1506command @code{step} accepts an argument which is the number of times to
1507step, as in @samp{step 5}. You can also use the @code{step} command
96a2c332 1508with no arguments. Some commands do not allow any arguments.
c906108c
SS
1509
1510@cindex abbreviation
1511@value{GDBN} command names may always be truncated if that abbreviation is
1512unambiguous. Other possible command abbreviations are listed in the
1513documentation for individual commands. In some cases, even ambiguous
1514abbreviations are allowed; for example, @code{s} is specially defined as
1515equivalent to @code{step} even though there are other commands whose
1516names start with @code{s}. You can test abbreviations by using them as
1517arguments to the @code{help} command.
1518
1519@cindex repeating commands
41afff9a 1520@kindex RET @r{(repeat last command)}
c906108c 1521A blank line as input to @value{GDBN} (typing just @key{RET}) means to
96a2c332 1522repeat the previous command. Certain commands (for example, @code{run})
c906108c
SS
1523will not repeat this way; these are commands whose unintentional
1524repetition might cause trouble and which you are unlikely to want to
c45da7e6
EZ
1525repeat. User-defined commands can disable this feature; see
1526@ref{Define, dont-repeat}.
c906108c
SS
1527
1528The @code{list} and @code{x} commands, when you repeat them with
1529@key{RET}, construct new arguments rather than repeating
1530exactly as typed. This permits easy scanning of source or memory.
1531
1532@value{GDBN} can also use @key{RET} in another way: to partition lengthy
1533output, in a way similar to the common utility @code{more}
79a6e687 1534(@pxref{Screen Size,,Screen Size}). Since it is easy to press one
c906108c
SS
1535@key{RET} too many in this situation, @value{GDBN} disables command
1536repetition after any command that generates this sort of display.
1537
41afff9a 1538@kindex # @r{(a comment)}
c906108c
SS
1539@cindex comment
1540Any text from a @kbd{#} to the end of the line is a comment; it does
1541nothing. This is useful mainly in command files (@pxref{Command
79a6e687 1542Files,,Command Files}).
c906108c 1543
88118b3a 1544@cindex repeating command sequences
c8aa23ab
EZ
1545@kindex Ctrl-o @r{(operate-and-get-next)}
1546The @kbd{Ctrl-o} binding is useful for repeating a complex sequence of
7f9087cb 1547commands. This command accepts the current line, like @key{RET}, and
88118b3a
TT
1548then fetches the next line relative to the current line from the history
1549for editing.
1550
6d2ebf8b 1551@node Completion
79a6e687 1552@section Command Completion
c906108c
SS
1553
1554@cindex completion
1555@cindex word completion
1556@value{GDBN} can fill in the rest of a word in a command for you, if there is
1557only one possibility; it can also show you what the valid possibilities
1558are for the next word in a command, at any time. This works for @value{GDBN}
1559commands, @value{GDBN} subcommands, and the names of symbols in your program.
1560
1561Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest
1562of a word. If there is only one possibility, @value{GDBN} fills in the
1563word, and waits for you to finish the command (or press @key{RET} to
1564enter it). For example, if you type
1565
1566@c FIXME "@key" does not distinguish its argument sufficiently to permit
1567@c complete accuracy in these examples; space introduced for clarity.
1568@c If texinfo enhancements make it unnecessary, it would be nice to
1569@c replace " @key" by "@key" in the following...
474c8240 1570@smallexample
c906108c 1571(@value{GDBP}) info bre @key{TAB}
474c8240 1572@end smallexample
c906108c
SS
1573
1574@noindent
1575@value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is
1576the only @code{info} subcommand beginning with @samp{bre}:
1577
474c8240 1578@smallexample
c906108c 1579(@value{GDBP}) info breakpoints
474c8240 1580@end smallexample
c906108c
SS
1581
1582@noindent
1583You can either press @key{RET} at this point, to run the @code{info
1584breakpoints} command, or backspace and enter something else, if
1585@samp{breakpoints} does not look like the command you expected. (If you
1586were sure you wanted @code{info breakpoints} in the first place, you
1587might as well just type @key{RET} immediately after @samp{info bre},
1588to exploit command abbreviations rather than command completion).
1589
1590If there is more than one possibility for the next word when you press
1591@key{TAB}, @value{GDBN} sounds a bell. You can either supply more
1592characters and try again, or just press @key{TAB} a second time;
1593@value{GDBN} displays all the possible completions for that word. For
1594example, you might want to set a breakpoint on a subroutine whose name
1595begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN}
1596just sounds the bell. Typing @key{TAB} again displays all the
1597function names in your program that begin with those characters, for
1598example:
1599
474c8240 1600@smallexample
c906108c
SS
1601(@value{GDBP}) b make_ @key{TAB}
1602@exdent @value{GDBN} sounds bell; press @key{TAB} again, to see:
5d161b24
DB
1603make_a_section_from_file make_environ
1604make_abs_section make_function_type
1605make_blockvector make_pointer_type
1606make_cleanup make_reference_type
c906108c
SS
1607make_command make_symbol_completion_list
1608(@value{GDBP}) b make_
474c8240 1609@end smallexample
c906108c
SS
1610
1611@noindent
1612After displaying the available possibilities, @value{GDBN} copies your
1613partial input (@samp{b make_} in the example) so you can finish the
1614command.
1615
1616If you just want to see the list of alternatives in the first place, you
b37052ae 1617can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?}
7a292a7a 1618means @kbd{@key{META} ?}. You can type this either by holding down a
c906108c 1619key designated as the @key{META} shift on your keyboard (if there is
7a292a7a 1620one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}.
c906108c 1621
ef0b411a
GB
1622If the number of possible completions is large, @value{GDBN} will
1623print as much of the list as it has collected, as well as a message
1624indicating that the list may be truncated.
1625
1626@smallexample
1627(@value{GDBP}) b m@key{TAB}@key{TAB}
1628main
1629<... the rest of the possible completions ...>
1630*** List may be truncated, max-completions reached. ***
1631(@value{GDBP}) b m
1632@end smallexample
1633
1634@noindent
1635This behavior can be controlled with the following commands:
1636
1637@table @code
1638@kindex set max-completions
1639@item set max-completions @var{limit}
1640@itemx set max-completions unlimited
1641Set the maximum number of completion candidates. @value{GDBN} will
1642stop looking for more completions once it collects this many candidates.
1643This is useful when completing on things like function names as collecting
1644all the possible candidates can be time consuming.
1645The default value is 200. A value of zero disables tab-completion.
1646Note that setting either no limit or a very large limit can make
1647completion slow.
1648@kindex show max-completions
1649@item show max-completions
1650Show the maximum number of candidates that @value{GDBN} will collect and show
1651during completion.
1652@end table
1653
c906108c
SS
1654@cindex quotes in commands
1655@cindex completion of quoted strings
1656Sometimes the string you need, while logically a ``word'', may contain
7a292a7a
SS
1657parentheses or other characters that @value{GDBN} normally excludes from
1658its notion of a word. To permit word completion to work in this
1659situation, you may enclose words in @code{'} (single quote marks) in
1660@value{GDBN} commands.
c906108c 1661
d044bac8
PA
1662A likely situation where you might need this is in typing an
1663expression that involves a C@t{++} symbol name with template
1664parameters. This is because when completing expressions, GDB treats
1665the @samp{<} character as word delimiter, assuming that it's the
1666less-than comparison operator (@pxref{C Operators, , C and C@t{++}
1667Operators}).
1668
1669For example, when you want to call a C@t{++} template function
1670interactively using the @code{print} or @code{call} commands, you may
1671need to distinguish whether you mean the version of @code{name} that
1672was specialized for @code{int}, @code{name<int>()}, or the version
1673that was specialized for @code{float}, @code{name<float>()}. To use
1674the word-completion facilities in this situation, type a single quote
b37052ae
EZ
1675@code{'} at the beginning of the function name. This alerts
1676@value{GDBN} that it may need to consider more information than usual
1677when you press @key{TAB} or @kbd{M-?} to request word completion:
c906108c 1678
474c8240 1679@smallexample
d044bac8
PA
1680(@value{GDBP}) p 'func< @kbd{M-?}
1681func<int>() func<float>()
1682(@value{GDBP}) p 'func<
474c8240 1683@end smallexample
c906108c 1684
d044bac8
PA
1685When setting breakpoints however (@pxref{Specify Location}), you don't
1686usually need to type a quote before the function name, because
1687@value{GDBN} understands that you want to set a breakpoint on a
1688function:
c906108c 1689
474c8240 1690@smallexample
d044bac8
PA
1691(@value{GDBP}) b func< @kbd{M-?}
1692func<int>() func<float>()
1693(@value{GDBP}) b func<
474c8240 1694@end smallexample
c906108c 1695
d044bac8
PA
1696This is true even in the case of typing the name of C@t{++} overloaded
1697functions (multiple definitions of the same function, distinguished by
1698argument type). For example, when you want to set a breakpoint you
1699don't need to distinguish whether you mean the version of @code{name}
1700that takes an @code{int} parameter, @code{name(int)}, or the version
1701that takes a @code{float} parameter, @code{name(float)}.
1702
1703@smallexample
1704(@value{GDBP}) b bubble( @kbd{M-?}
1705bubble(int) bubble(double)
1706(@value{GDBP}) b bubble(dou @kbd{M-?}
1707bubble(double)
1708@end smallexample
1709
1710See @ref{quoting names} for a description of other scenarios that
1711require quoting.
c906108c 1712
79a6e687
BW
1713For more information about overloaded functions, see @ref{C Plus Plus
1714Expressions, ,C@t{++} Expressions}. You can use the command @code{set
c906108c 1715overload-resolution off} to disable overload resolution;
79a6e687 1716see @ref{Debugging C Plus Plus, ,@value{GDBN} Features for C@t{++}}.
c906108c 1717
65d12d83
TT
1718@cindex completion of structure field names
1719@cindex structure field name completion
1720@cindex completion of union field names
1721@cindex union field name completion
1722When completing in an expression which looks up a field in a
1723structure, @value{GDBN} also tries@footnote{The completer can be
1724confused by certain kinds of invalid expressions. Also, it only
1725examines the static type of the expression, not the dynamic type.} to
1726limit completions to the field names available in the type of the
1727left-hand-side:
1728
1729@smallexample
1730(@value{GDBP}) p gdb_stdout.@kbd{M-?}
01124a23
DE
1731magic to_fputs to_rewind
1732to_data to_isatty to_write
1733to_delete to_put to_write_async_safe
1734to_flush to_read
65d12d83
TT
1735@end smallexample
1736
1737@noindent
1738This is because the @code{gdb_stdout} is a variable of the type
1739@code{struct ui_file} that is defined in @value{GDBN} sources as
1740follows:
1741
1742@smallexample
1743struct ui_file
1744@{
1745 int *magic;
1746 ui_file_flush_ftype *to_flush;
1747 ui_file_write_ftype *to_write;
01124a23 1748 ui_file_write_async_safe_ftype *to_write_async_safe;
65d12d83
TT
1749 ui_file_fputs_ftype *to_fputs;
1750 ui_file_read_ftype *to_read;
1751 ui_file_delete_ftype *to_delete;
1752 ui_file_isatty_ftype *to_isatty;
1753 ui_file_rewind_ftype *to_rewind;
1754 ui_file_put_ftype *to_put;
1755 void *to_data;
1756@}
1757@end smallexample
1758
c906108c 1759
6d2ebf8b 1760@node Help
79a6e687 1761@section Getting Help
c906108c
SS
1762@cindex online documentation
1763@kindex help
1764
5d161b24 1765You can always ask @value{GDBN} itself for information on its commands,
c906108c
SS
1766using the command @code{help}.
1767
1768@table @code
41afff9a 1769@kindex h @r{(@code{help})}
c906108c
SS
1770@item help
1771@itemx h
1772You can use @code{help} (abbreviated @code{h}) with no arguments to
1773display a short list of named classes of commands:
1774
1775@smallexample
1776(@value{GDBP}) help
1777List of classes of commands:
1778
2df3850c 1779aliases -- Aliases of other commands
c906108c 1780breakpoints -- Making program stop at certain points
2df3850c 1781data -- Examining data
c906108c 1782files -- Specifying and examining files
2df3850c
JM
1783internals -- Maintenance commands
1784obscure -- Obscure features
1785running -- Running the program
1786stack -- Examining the stack
c906108c
SS
1787status -- Status inquiries
1788support -- Support facilities
12c27660 1789tracepoints -- Tracing of program execution without
96a2c332 1790 stopping the program
c906108c 1791user-defined -- User-defined commands
c906108c 1792
5d161b24 1793Type "help" followed by a class name for a list of
c906108c 1794commands in that class.
5d161b24 1795Type "help" followed by command name for full
c906108c
SS
1796documentation.
1797Command name abbreviations are allowed if unambiguous.
1798(@value{GDBP})
1799@end smallexample
96a2c332 1800@c the above line break eliminates huge line overfull...
c906108c
SS
1801
1802@item help @var{class}
1803Using one of the general help classes as an argument, you can get a
1804list of the individual commands in that class. For example, here is the
1805help display for the class @code{status}:
1806
1807@smallexample
1808(@value{GDBP}) help status
1809Status inquiries.
1810
1811List of commands:
1812
1813@c Line break in "show" line falsifies real output, but needed
1814@c to fit in smallbook page size.
2df3850c 1815info -- Generic command for showing things
12c27660 1816 about the program being debugged
2df3850c 1817show -- Generic command for showing things
12c27660 1818 about the debugger
c906108c 1819
5d161b24 1820Type "help" followed by command name for full
c906108c
SS
1821documentation.
1822Command name abbreviations are allowed if unambiguous.
1823(@value{GDBP})
1824@end smallexample
1825
1826@item help @var{command}
1827With a command name as @code{help} argument, @value{GDBN} displays a
1828short paragraph on how to use that command.
1829
6837a0a2
DB
1830@kindex apropos
1831@item apropos @var{args}
09d4efe1 1832The @code{apropos} command searches through all of the @value{GDBN}
6837a0a2 1833commands, and their documentation, for the regular expression specified in
99e008fe 1834@var{args}. It prints out all matches found. For example:
6837a0a2
DB
1835
1836@smallexample
16899756 1837apropos alias
6837a0a2
DB
1838@end smallexample
1839
b37052ae
EZ
1840@noindent
1841results in:
6837a0a2
DB
1842
1843@smallexample
6d2ebf8b 1844@c @group
16899756
DE
1845alias -- Define a new command that is an alias of an existing command
1846aliases -- Aliases of other commands
1847d -- Delete some breakpoints or auto-display expressions
1848del -- Delete some breakpoints or auto-display expressions
1849delete -- Delete some breakpoints or auto-display expressions
6d2ebf8b 1850@c @end group
6837a0a2
DB
1851@end smallexample
1852
c906108c
SS
1853@kindex complete
1854@item complete @var{args}
1855The @code{complete @var{args}} command lists all the possible completions
1856for the beginning of a command. Use @var{args} to specify the beginning of the
1857command you want completed. For example:
1858
1859@smallexample
1860complete i
1861@end smallexample
1862
1863@noindent results in:
1864
1865@smallexample
1866@group
2df3850c
JM
1867if
1868ignore
c906108c
SS
1869info
1870inspect
c906108c
SS
1871@end group
1872@end smallexample
1873
1874@noindent This is intended for use by @sc{gnu} Emacs.
1875@end table
1876
1877In addition to @code{help}, you can use the @value{GDBN} commands @code{info}
1878and @code{show} to inquire about the state of your program, or the state
1879of @value{GDBN} itself. Each command supports many topics of inquiry; this
1880manual introduces each of them in the appropriate context. The listings
00595b5e
EZ
1881under @code{info} and under @code{show} in the Command, Variable, and
1882Function Index point to all the sub-commands. @xref{Command and Variable
1883Index}.
c906108c
SS
1884
1885@c @group
1886@table @code
1887@kindex info
41afff9a 1888@kindex i @r{(@code{info})}
c906108c
SS
1889@item info
1890This command (abbreviated @code{i}) is for describing the state of your
cda4ce5a 1891program. For example, you can show the arguments passed to a function
c906108c
SS
1892with @code{info args}, list the registers currently in use with @code{info
1893registers}, or list the breakpoints you have set with @code{info breakpoints}.
1894You can get a complete list of the @code{info} sub-commands with
1895@w{@code{help info}}.
1896
1897@kindex set
1898@item set
5d161b24 1899You can assign the result of an expression to an environment variable with
c906108c
SS
1900@code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with
1901@code{set prompt $}.
1902
1903@kindex show
1904@item show
5d161b24 1905In contrast to @code{info}, @code{show} is for describing the state of
c906108c
SS
1906@value{GDBN} itself.
1907You can change most of the things you can @code{show}, by using the
1908related command @code{set}; for example, you can control what number
1909system is used for displays with @code{set radix}, or simply inquire
1910which is currently in use with @code{show radix}.
1911
1912@kindex info set
1913To display all the settable parameters and their current
1914values, you can use @code{show} with no arguments; you may also use
1915@code{info set}. Both commands produce the same display.
1916@c FIXME: "info set" violates the rule that "info" is for state of
1917@c FIXME...program. Ck w/ GNU: "info set" to be called something else,
1918@c FIXME...or change desc of rule---eg "state of prog and debugging session"?
1919@end table
1920@c @end group
1921
6eaaf48b 1922Here are several miscellaneous @code{show} subcommands, all of which are
c906108c
SS
1923exceptional in lacking corresponding @code{set} commands:
1924
1925@table @code
1926@kindex show version
9c16f35a 1927@cindex @value{GDBN} version number
c906108c
SS
1928@item show version
1929Show what version of @value{GDBN} is running. You should include this
2df3850c
JM
1930information in @value{GDBN} bug-reports. If multiple versions of
1931@value{GDBN} are in use at your site, you may need to determine which
1932version of @value{GDBN} you are running; as @value{GDBN} evolves, new
1933commands are introduced, and old ones may wither away. Also, many
1934system vendors ship variant versions of @value{GDBN}, and there are
96a2c332 1935variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well.
2df3850c
JM
1936The version number is the same as the one announced when you start
1937@value{GDBN}.
c906108c
SS
1938
1939@kindex show copying
09d4efe1 1940@kindex info copying
9c16f35a 1941@cindex display @value{GDBN} copyright
c906108c 1942@item show copying
09d4efe1 1943@itemx info copying
c906108c
SS
1944Display information about permission for copying @value{GDBN}.
1945
1946@kindex show warranty
09d4efe1 1947@kindex info warranty
c906108c 1948@item show warranty
09d4efe1 1949@itemx info warranty
2df3850c 1950Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty,
96a2c332 1951if your version of @value{GDBN} comes with one.
2df3850c 1952
6eaaf48b
EZ
1953@kindex show configuration
1954@item show configuration
1955Display detailed information about the way @value{GDBN} was configured
1956when it was built. This displays the optional arguments passed to the
1957@file{configure} script and also configuration parameters detected
1958automatically by @command{configure}. When reporting a @value{GDBN}
1959bug (@pxref{GDB Bugs}), it is important to include this information in
1960your report.
1961
c906108c
SS
1962@end table
1963
6d2ebf8b 1964@node Running
c906108c
SS
1965@chapter Running Programs Under @value{GDBN}
1966
1967When you run a program under @value{GDBN}, you must first generate
1968debugging information when you compile it.
7a292a7a
SS
1969
1970You may start @value{GDBN} with its arguments, if any, in an environment
1971of your choice. If you are doing native debugging, you may redirect
1972your program's input and output, debug an already running process, or
1973kill a child process.
c906108c
SS
1974
1975@menu
1976* Compilation:: Compiling for debugging
1977* Starting:: Starting your program
c906108c
SS
1978* Arguments:: Your program's arguments
1979* Environment:: Your program's environment
c906108c
SS
1980
1981* Working Directory:: Your program's working directory
1982* Input/Output:: Your program's input and output
1983* Attach:: Debugging an already-running process
1984* Kill Process:: Killing the child process
c906108c 1985
6c95b8df 1986* Inferiors and Programs:: Debugging multiple inferiors and programs
c906108c 1987* Threads:: Debugging programs with multiple threads
6c95b8df 1988* Forks:: Debugging forks
5c95884b 1989* Checkpoint/Restart:: Setting a @emph{bookmark} to return to later
c906108c
SS
1990@end menu
1991
6d2ebf8b 1992@node Compilation
79a6e687 1993@section Compiling for Debugging
c906108c
SS
1994
1995In order to debug a program effectively, you need to generate
1996debugging information when you compile it. This debugging information
1997is stored in the object file; it describes the data type of each
1998variable or function and the correspondence between source line numbers
1999and addresses in the executable code.
2000
2001To request debugging information, specify the @samp{-g} option when you run
2002the compiler.
2003
514c4d71 2004Programs that are to be shipped to your customers are compiled with
edb3359d 2005optimizations, using the @samp{-O} compiler option. However, some
514c4d71
EZ
2006compilers are unable to handle the @samp{-g} and @samp{-O} options
2007together. Using those compilers, you cannot generate optimized
c906108c
SS
2008executables containing debugging information.
2009
514c4d71 2010@value{NGCC}, the @sc{gnu} C/C@t{++} compiler, supports @samp{-g} with or
53a5351d
JM
2011without @samp{-O}, making it possible to debug optimized code. We
2012recommend that you @emph{always} use @samp{-g} whenever you compile a
2013program. You may think your program is correct, but there is no sense
edb3359d 2014in pushing your luck. For more information, see @ref{Optimized Code}.
c906108c
SS
2015
2016Older versions of the @sc{gnu} C compiler permitted a variant option
2017@w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this
2018format; if your @sc{gnu} C compiler has this option, do not use it.
2019
514c4d71
EZ
2020@value{GDBN} knows about preprocessor macros and can show you their
2021expansion (@pxref{Macros}). Most compilers do not include information
2022about preprocessor macros in the debugging information if you specify
e0f8f636
TT
2023the @option{-g} flag alone. Version 3.1 and later of @value{NGCC},
2024the @sc{gnu} C compiler, provides macro information if you are using
2025the DWARF debugging format, and specify the option @option{-g3}.
2026
2027@xref{Debugging Options,,Options for Debugging Your Program or GCC,
f5a476a7 2028gcc, Using the @sc{gnu} Compiler Collection (GCC)}, for more
e0f8f636
TT
2029information on @value{NGCC} options affecting debug information.
2030
2031You will have the best debugging experience if you use the latest
2032version of the DWARF debugging format that your compiler supports.
2033DWARF is currently the most expressive and best supported debugging
2034format in @value{GDBN}.
514c4d71 2035
c906108c 2036@need 2000
6d2ebf8b 2037@node Starting
79a6e687 2038@section Starting your Program
c906108c
SS
2039@cindex starting
2040@cindex running
2041
2042@table @code
2043@kindex run
41afff9a 2044@kindex r @r{(@code{run})}
c906108c
SS
2045@item run
2046@itemx r
7a292a7a 2047Use the @code{run} command to start your program under @value{GDBN}.
deb8ff2b
PA
2048You must first specify the program name with an argument to
2049@value{GDBN} (@pxref{Invocation, ,Getting In and Out of
2050@value{GDBN}}), or by using the @code{file} or @code{exec-file}
2051command (@pxref{Files, ,Commands to Specify Files}).
c906108c
SS
2052
2053@end table
2054
c906108c
SS
2055If you are running your program in an execution environment that
2056supports processes, @code{run} creates an inferior process and makes
8edfe269
DJ
2057that process run your program. In some environments without processes,
2058@code{run} jumps to the start of your program. Other targets,
2059like @samp{remote}, are always running. If you get an error
2060message like this one:
2061
2062@smallexample
2063The "remote" target does not support "run".
2064Try "help target" or "continue".
2065@end smallexample
2066
2067@noindent
2068then use @code{continue} to run your program. You may need @code{load}
2069first (@pxref{load}).
c906108c
SS
2070
2071The execution of a program is affected by certain information it
2072receives from its superior. @value{GDBN} provides ways to specify this
2073information, which you must do @emph{before} starting your program. (You
2074can change it after starting your program, but such changes only affect
2075your program the next time you start it.) This information may be
2076divided into four categories:
2077
2078@table @asis
2079@item The @emph{arguments.}
2080Specify the arguments to give your program as the arguments of the
2081@code{run} command. If a shell is available on your target, the shell
2082is used to pass the arguments, so that you may use normal conventions
2083(such as wildcard expansion or variable substitution) in describing
2084the arguments.
2085In Unix systems, you can control which shell is used with the
98882a26
PA
2086@code{SHELL} environment variable. If you do not define @code{SHELL},
2087@value{GDBN} uses the default shell (@file{/bin/sh}). You can disable
2088use of any shell with the @code{set startup-with-shell} command (see
2089below for details).
c906108c
SS
2090
2091@item The @emph{environment.}
2092Your program normally inherits its environment from @value{GDBN}, but you can
2093use the @value{GDBN} commands @code{set environment} and @code{unset
2094environment} to change parts of the environment that affect
79a6e687 2095your program. @xref{Environment, ,Your Program's Environment}.
c906108c
SS
2096
2097@item The @emph{working directory.}
d092c5a2
SDJ
2098You can set your program's working directory with the command
2099@kbd{set cwd}. If you do not set any working directory with this
bc3b087d
SDJ
2100command, your program will inherit @value{GDBN}'s working directory if
2101native debugging, or the remote server's working directory if remote
2102debugging. @xref{Working Directory, ,Your Program's Working
2103Directory}.
c906108c
SS
2104
2105@item The @emph{standard input and output.}
2106Your program normally uses the same device for standard input and
2107standard output as @value{GDBN} is using. You can redirect input and output
2108in the @code{run} command line, or you can use the @code{tty} command to
2109set a different device for your program.
79a6e687 2110@xref{Input/Output, ,Your Program's Input and Output}.
c906108c
SS
2111
2112@cindex pipes
2113@emph{Warning:} While input and output redirection work, you cannot use
2114pipes to pass the output of the program you are debugging to another
2115program; if you attempt this, @value{GDBN} is likely to wind up debugging the
2116wrong program.
2117@end table
c906108c
SS
2118
2119When you issue the @code{run} command, your program begins to execute
79a6e687 2120immediately. @xref{Stopping, ,Stopping and Continuing}, for discussion
c906108c
SS
2121of how to arrange for your program to stop. Once your program has
2122stopped, you may call functions in your program, using the @code{print}
2123or @code{call} commands. @xref{Data, ,Examining Data}.
2124
2125If the modification time of your symbol file has changed since the last
2126time @value{GDBN} read its symbols, @value{GDBN} discards its symbol
2127table, and reads it again. When it does this, @value{GDBN} tries to retain
2128your current breakpoints.
2129
4e8b0763
JB
2130@table @code
2131@kindex start
2132@item start
2133@cindex run to main procedure
2134The name of the main procedure can vary from language to language.
2135With C or C@t{++}, the main procedure name is always @code{main}, but
2136other languages such as Ada do not require a specific name for their
2137main procedure. The debugger provides a convenient way to start the
2138execution of the program and to stop at the beginning of the main
2139procedure, depending on the language used.
2140
2141The @samp{start} command does the equivalent of setting a temporary
2142breakpoint at the beginning of the main procedure and then invoking
2143the @samp{run} command.
2144
f018e82f
EZ
2145@cindex elaboration phase
2146Some programs contain an @dfn{elaboration} phase where some startup code is
2147executed before the main procedure is called. This depends on the
2148languages used to write your program. In C@t{++}, for instance,
4e8b0763
JB
2149constructors for static and global objects are executed before
2150@code{main} is called. It is therefore possible that the debugger stops
2151before reaching the main procedure. However, the temporary breakpoint
2152will remain to halt execution.
2153
2154Specify the arguments to give to your program as arguments to the
2155@samp{start} command. These arguments will be given verbatim to the
2156underlying @samp{run} command. Note that the same arguments will be
2157reused if no argument is provided during subsequent calls to
2158@samp{start} or @samp{run}.
2159
2160It is sometimes necessary to debug the program during elaboration. In
4e5a4f58
JB
2161these cases, using the @code{start} command would stop the execution
2162of your program too late, as the program would have already completed
2163the elaboration phase. Under these circumstances, either insert
2164breakpoints in your elaboration code before running your program or
2165use the @code{starti} command.
2166
2167@kindex starti
2168@item starti
2169@cindex run to first instruction
2170The @samp{starti} command does the equivalent of setting a temporary
2171breakpoint at the first instruction of a program's execution and then
2172invoking the @samp{run} command. For programs containing an
2173elaboration phase, the @code{starti} command will stop execution at
2174the start of the elaboration phase.
ccd213ac 2175
41ef2965 2176@anchor{set exec-wrapper}
ccd213ac
DJ
2177@kindex set exec-wrapper
2178@item set exec-wrapper @var{wrapper}
2179@itemx show exec-wrapper
2180@itemx unset exec-wrapper
2181When @samp{exec-wrapper} is set, the specified wrapper is used to
2182launch programs for debugging. @value{GDBN} starts your program
2183with a shell command of the form @kbd{exec @var{wrapper}
2184@var{program}}. Quoting is added to @var{program} and its
2185arguments, but not to @var{wrapper}, so you should add quotes if
2186appropriate for your shell. The wrapper runs until it executes
2187your program, and then @value{GDBN} takes control.
2188
2189You can use any program that eventually calls @code{execve} with
2190its arguments as a wrapper. Several standard Unix utilities do
2191this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending
2192with @code{exec "$@@"} will also work.
2193
2194For example, you can use @code{env} to pass an environment variable to
2195the debugged program, without setting the variable in your shell's
2196environment:
2197
2198@smallexample
2199(@value{GDBP}) set exec-wrapper env 'LD_PRELOAD=libtest.so'
2200(@value{GDBP}) run
2201@end smallexample
2202
2203This command is available when debugging locally on most targets, excluding
2204@sc{djgpp}, Cygwin, MS Windows, and QNX Neutrino.
2205
98882a26 2206@kindex set startup-with-shell
aefd8b33 2207@anchor{set startup-with-shell}
98882a26
PA
2208@item set startup-with-shell
2209@itemx set startup-with-shell on
2210@itemx set startup-with-shell off
ca145713 2211@itemx show startup-with-shell
98882a26
PA
2212On Unix systems, by default, if a shell is available on your target,
2213@value{GDBN}) uses it to start your program. Arguments of the
2214@code{run} command are passed to the shell, which does variable
2215substitution, expands wildcard characters and performs redirection of
2216I/O. In some circumstances, it may be useful to disable such use of a
2217shell, for example, when debugging the shell itself or diagnosing
2218startup failures such as:
2219
2220@smallexample
2221(@value{GDBP}) run
2222Starting program: ./a.out
2223During startup program terminated with signal SIGSEGV, Segmentation fault.
2224@end smallexample
2225
2226@noindent
2227which indicates the shell or the wrapper specified with
2228@samp{exec-wrapper} crashed, not your program. Most often, this is
afa332ce
PA
2229caused by something odd in your shell's non-interactive mode
2230initialization file---such as @file{.cshrc} for C-shell,
2231$@file{.zshenv} for the Z shell, or the file specified in the
2232@samp{BASH_ENV} environment variable for BASH.
98882a26 2233
6a3cb8e8
PA
2234@anchor{set auto-connect-native-target}
2235@kindex set auto-connect-native-target
2236@item set auto-connect-native-target
2237@itemx set auto-connect-native-target on
2238@itemx set auto-connect-native-target off
2239@itemx show auto-connect-native-target
2240
2241By default, if not connected to any target yet (e.g., with
2242@code{target remote}), the @code{run} command starts your program as a
2243native process under @value{GDBN}, on your local machine. If you're
2244sure you don't want to debug programs on your local machine, you can
2245tell @value{GDBN} to not connect to the native target automatically
2246with the @code{set auto-connect-native-target off} command.
2247
2248If @code{on}, which is the default, and if @value{GDBN} is not
2249connected to a target already, the @code{run} command automaticaly
2250connects to the native target, if one is available.
2251
2252If @code{off}, and if @value{GDBN} is not connected to a target
2253already, the @code{run} command fails with an error:
2254
2255@smallexample
2256(@value{GDBP}) run
2257Don't know how to run. Try "help target".
2258@end smallexample
2259
2260If @value{GDBN} is already connected to a target, @value{GDBN} always
2261uses it with the @code{run} command.
2262
2263In any case, you can explicitly connect to the native target with the
2264@code{target native} command. For example,
2265
2266@smallexample
2267(@value{GDBP}) set auto-connect-native-target off
2268(@value{GDBP}) run
2269Don't know how to run. Try "help target".
2270(@value{GDBP}) target native
2271(@value{GDBP}) run
2272Starting program: ./a.out
2273[Inferior 1 (process 10421) exited normally]
2274@end smallexample
2275
2276In case you connected explicitly to the @code{native} target,
2277@value{GDBN} remains connected even if all inferiors exit, ready for
2278the next @code{run} command. Use the @code{disconnect} command to
2279disconnect.
2280
2281Examples of other commands that likewise respect the
2282@code{auto-connect-native-target} setting: @code{attach}, @code{info
2283proc}, @code{info os}.
2284
10568435
JK
2285@kindex set disable-randomization
2286@item set disable-randomization
2287@itemx set disable-randomization on
2288This option (enabled by default in @value{GDBN}) will turn off the native
2289randomization of the virtual address space of the started program. This option
2290is useful for multiple debugging sessions to make the execution better
2291reproducible and memory addresses reusable across debugging sessions.
2292
03583c20
UW
2293This feature is implemented only on certain targets, including @sc{gnu}/Linux.
2294On @sc{gnu}/Linux you can get the same behavior using
10568435
JK
2295
2296@smallexample
2297(@value{GDBP}) set exec-wrapper setarch `uname -m` -R
2298@end smallexample
2299
2300@item set disable-randomization off
2301Leave the behavior of the started executable unchanged. Some bugs rear their
2302ugly heads only when the program is loaded at certain addresses. If your bug
2303disappears when you run the program under @value{GDBN}, that might be because
2304@value{GDBN} by default disables the address randomization on platforms, such
2305as @sc{gnu}/Linux, which do that for stand-alone programs. Use @kbd{set
2306disable-randomization off} to try to reproduce such elusive bugs.
2307
03583c20
UW
2308On targets where it is available, virtual address space randomization
2309protects the programs against certain kinds of security attacks. In these
10568435
JK
2310cases the attacker needs to know the exact location of a concrete executable
2311code. Randomizing its location makes it impossible to inject jumps misusing
2312a code at its expected addresses.
2313
2314Prelinking shared libraries provides a startup performance advantage but it
2315makes addresses in these libraries predictable for privileged processes by
2316having just unprivileged access at the target system. Reading the shared
2317library binary gives enough information for assembling the malicious code
2318misusing it. Still even a prelinked shared library can get loaded at a new
2319random address just requiring the regular relocation process during the
2320startup. Shared libraries not already prelinked are always loaded at
2321a randomly chosen address.
2322
2323Position independent executables (PIE) contain position independent code
2324similar to the shared libraries and therefore such executables get loaded at
2325a randomly chosen address upon startup. PIE executables always load even
2326already prelinked shared libraries at a random address. You can build such
2327executable using @command{gcc -fPIE -pie}.
2328
2329Heap (malloc storage), stack and custom mmap areas are always placed randomly
2330(as long as the randomization is enabled).
2331
2332@item show disable-randomization
2333Show the current setting of the explicit disable of the native randomization of
2334the virtual address space of the started program.
2335
4e8b0763
JB
2336@end table
2337
6d2ebf8b 2338@node Arguments
79a6e687 2339@section Your Program's Arguments
c906108c
SS
2340
2341@cindex arguments (to your program)
2342The arguments to your program can be specified by the arguments of the
5d161b24 2343@code{run} command.
c906108c
SS
2344They are passed to a shell, which expands wildcard characters and
2345performs redirection of I/O, and thence to your program. Your
2346@code{SHELL} environment variable (if it exists) specifies what shell
2347@value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses
d4f3574e
SS
2348the default shell (@file{/bin/sh} on Unix).
2349
2350On non-Unix systems, the program is usually invoked directly by
2351@value{GDBN}, which emulates I/O redirection via the appropriate system
2352calls, and the wildcard characters are expanded by the startup code of
2353the program, not by the shell.
c906108c
SS
2354
2355@code{run} with no arguments uses the same arguments used by the previous
2356@code{run}, or those set by the @code{set args} command.
2357
c906108c 2358@table @code
41afff9a 2359@kindex set args
c906108c
SS
2360@item set args
2361Specify the arguments to be used the next time your program is run. If
2362@code{set args} has no arguments, @code{run} executes your program
2363with no arguments. Once you have run your program with arguments,
2364using @code{set args} before the next @code{run} is the only way to run
2365it again without arguments.
2366
2367@kindex show args
2368@item show args
2369Show the arguments to give your program when it is started.
2370@end table
2371
6d2ebf8b 2372@node Environment
79a6e687 2373@section Your Program's Environment
c906108c
SS
2374
2375@cindex environment (of your program)
2376The @dfn{environment} consists of a set of environment variables and
2377their values. Environment variables conventionally record such things as
2378your user name, your home directory, your terminal type, and your search
2379path for programs to run. Usually you set up environment variables with
2380the shell and they are inherited by all the other programs you run. When
2381debugging, it can be useful to try running your program with a modified
2382environment without having to start @value{GDBN} over again.
2383
2384@table @code
2385@kindex path
2386@item path @var{directory}
2387Add @var{directory} to the front of the @code{PATH} environment variable
17cc6a06
EZ
2388(the search path for executables) that will be passed to your program.
2389The value of @code{PATH} used by @value{GDBN} does not change.
d4f3574e
SS
2390You may specify several directory names, separated by whitespace or by a
2391system-dependent separator character (@samp{:} on Unix, @samp{;} on
2392MS-DOS and MS-Windows). If @var{directory} is already in the path, it
2393is moved to the front, so it is searched sooner.
c906108c
SS
2394
2395You can use the string @samp{$cwd} to refer to whatever is the current
2396working directory at the time @value{GDBN} searches the path. If you
2397use @samp{.} instead, it refers to the directory where you executed the
2398@code{path} command. @value{GDBN} replaces @samp{.} in the
2399@var{directory} argument (with the current path) before adding
2400@var{directory} to the search path.
2401@c 'path' is explicitly nonrepeatable, but RMS points out it is silly to
2402@c document that, since repeating it would be a no-op.
2403
2404@kindex show paths
2405@item show paths
2406Display the list of search paths for executables (the @code{PATH}
2407environment variable).
2408
2409@kindex show environment
2410@item show environment @r{[}@var{varname}@r{]}
2411Print the value of environment variable @var{varname} to be given to
2412your program when it starts. If you do not supply @var{varname},
2413print the names and values of all environment variables to be given to
2414your program. You can abbreviate @code{environment} as @code{env}.
2415
2416@kindex set environment
0a2dde4a 2417@anchor{set environment}
53a5351d 2418@item set environment @var{varname} @r{[}=@var{value}@r{]}
c906108c 2419Set environment variable @var{varname} to @var{value}. The value
41ef2965 2420changes for your program (and the shell @value{GDBN} uses to launch
697aa1b7 2421it), not for @value{GDBN} itself. The @var{value} may be any string; the
41ef2965
PA
2422values of environment variables are just strings, and any
2423interpretation is supplied by your program itself. The @var{value}
c906108c
SS
2424parameter is optional; if it is eliminated, the variable is set to a
2425null value.
2426@c "any string" here does not include leading, trailing
2427@c blanks. Gnu asks: does anyone care?
2428
2429For example, this command:
2430
474c8240 2431@smallexample
c906108c 2432set env USER = foo
474c8240 2433@end smallexample
c906108c
SS
2434
2435@noindent
d4f3574e 2436tells the debugged program, when subsequently run, that its user is named
c906108c
SS
2437@samp{foo}. (The spaces around @samp{=} are used for clarity here; they
2438are not actually required.)
2439
41ef2965
PA
2440Note that on Unix systems, @value{GDBN} runs your program via a shell,
2441which also inherits the environment set with @code{set environment}.
2442If necessary, you can avoid that by using the @samp{env} program as a
2443wrapper instead of using @code{set environment}. @xref{set
2444exec-wrapper}, for an example doing just that.
2445
0a2dde4a
SDJ
2446Environment variables that are set by the user are also transmitted to
2447@command{gdbserver} to be used when starting the remote inferior.
2448@pxref{QEnvironmentHexEncoded}.
2449
c906108c 2450@kindex unset environment
0a2dde4a 2451@anchor{unset environment}
c906108c
SS
2452@item unset environment @var{varname}
2453Remove variable @var{varname} from the environment to be passed to your
2454program. This is different from @samp{set env @var{varname} =};
2455@code{unset environment} removes the variable from the environment,
2456rather than assigning it an empty value.
0a2dde4a
SDJ
2457
2458Environment variables that are unset by the user are also unset on
2459@command{gdbserver} when starting the remote inferior.
2460@pxref{QEnvironmentUnset}.
c906108c
SS
2461@end table
2462
d4f3574e 2463@emph{Warning:} On Unix systems, @value{GDBN} runs your program using
afa332ce
PA
2464the shell indicated by your @code{SHELL} environment variable if it
2465exists (or @code{/bin/sh} if not). If your @code{SHELL} variable
2466names a shell that runs an initialization file when started
2467non-interactively---such as @file{.cshrc} for C-shell, $@file{.zshenv}
2468for the Z shell, or the file specified in the @samp{BASH_ENV}
2469environment variable for BASH---any variables you set in that file
2470affect your program. You may wish to move setting of environment
2471variables to files that are only run when you sign on, such as
2472@file{.login} or @file{.profile}.
c906108c 2473
6d2ebf8b 2474@node Working Directory
79a6e687 2475@section Your Program's Working Directory
c906108c
SS
2476
2477@cindex working directory (of your program)
d092c5a2
SDJ
2478Each time you start your program with @code{run}, the inferior will be
2479initialized with the current working directory specified by the
2480@kbd{set cwd} command. If no directory has been specified by this
2481command, then the inferior will inherit @value{GDBN}'s current working
bc3b087d
SDJ
2482directory as its working directory if native debugging, or it will
2483inherit the remote server's current working directory if remote
2484debugging.
c906108c
SS
2485
2486@table @code
d092c5a2
SDJ
2487@kindex set cwd
2488@cindex change inferior's working directory
2489@anchor{set cwd command}
2490@item set cwd @r{[}@var{directory}@r{]}
2491Set the inferior's working directory to @var{directory}, which will be
2492@code{glob}-expanded in order to resolve tildes (@file{~}). If no
2493argument has been specified, the command clears the setting and resets
2494it to an empty state. This setting has no effect on @value{GDBN}'s
2495working directory, and it only takes effect the next time you start
2496the inferior. The @file{~} in @var{directory} is a short for the
2497@dfn{home directory}, usually pointed to by the @env{HOME} environment
2498variable. On MS-Windows, if @env{HOME} is not defined, @value{GDBN}
2499uses the concatenation of @env{HOMEDRIVE} and @env{HOMEPATH} as
2500fallback.
2501
2502You can also change @value{GDBN}'s current working directory by using
2503the @code{cd} command.
dbfa4523 2504@xref{cd command}.
d092c5a2
SDJ
2505
2506@kindex show cwd
2507@cindex show inferior's working directory
2508@item show cwd
2509Show the inferior's working directory. If no directory has been
2510specified by @kbd{set cwd}, then the default inferior's working
2511directory is the same as @value{GDBN}'s working directory.
2512
c906108c 2513@kindex cd
d092c5a2
SDJ
2514@cindex change @value{GDBN}'s working directory
2515@anchor{cd command}
f3c8a52a
JK
2516@item cd @r{[}@var{directory}@r{]}
2517Set the @value{GDBN} working directory to @var{directory}. If not
2518given, @var{directory} uses @file{'~'}.
c906108c 2519
d092c5a2
SDJ
2520The @value{GDBN} working directory serves as a default for the
2521commands that specify files for @value{GDBN} to operate on.
2522@xref{Files, ,Commands to Specify Files}.
dbfa4523 2523@xref{set cwd command}.
d092c5a2 2524
c906108c
SS
2525@kindex pwd
2526@item pwd
2527Print the @value{GDBN} working directory.
2528@end table
2529
60bf7e09
EZ
2530It is generally impossible to find the current working directory of
2531the process being debugged (since a program can change its directory
2d97a5d9 2532during its run). If you work on a system where @value{GDBN} supports
754452f0 2533the @code{info proc} command (@pxref{Process Information}), you can
2d97a5d9 2534use the @code{info proc} command to find out the
60bf7e09
EZ
2535current working directory of the debuggee.
2536
6d2ebf8b 2537@node Input/Output
79a6e687 2538@section Your Program's Input and Output
c906108c
SS
2539
2540@cindex redirection
2541@cindex i/o
2542@cindex terminal
2543By default, the program you run under @value{GDBN} does input and output to
5d161b24 2544the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal
c906108c
SS
2545to its own terminal modes to interact with you, but it records the terminal
2546modes your program was using and switches back to them when you continue
2547running your program.
2548
2549@table @code
2550@kindex info terminal
2551@item info terminal
2552Displays information recorded by @value{GDBN} about the terminal modes your
2553program is using.
2554@end table
2555
2556You can redirect your program's input and/or output using shell
2557redirection with the @code{run} command. For example,
2558
474c8240 2559@smallexample
c906108c 2560run > outfile
474c8240 2561@end smallexample
c906108c
SS
2562
2563@noindent
2564starts your program, diverting its output to the file @file{outfile}.
2565
2566@kindex tty
2567@cindex controlling terminal
2568Another way to specify where your program should do input and output is
2569with the @code{tty} command. This command accepts a file name as
2570argument, and causes this file to be the default for future @code{run}
2571commands. It also resets the controlling terminal for the child
2572process, for future @code{run} commands. For example,
2573
474c8240 2574@smallexample
c906108c 2575tty /dev/ttyb
474c8240 2576@end smallexample
c906108c
SS
2577
2578@noindent
2579directs that processes started with subsequent @code{run} commands
2580default to do input and output on the terminal @file{/dev/ttyb} and have
2581that as their controlling terminal.
2582
2583An explicit redirection in @code{run} overrides the @code{tty} command's
2584effect on the input/output device, but not its effect on the controlling
2585terminal.
2586
2587When you use the @code{tty} command or redirect input in the @code{run}
2588command, only the input @emph{for your program} is affected. The input
3cb3b8df
BR
2589for @value{GDBN} still comes from your terminal. @code{tty} is an alias
2590for @code{set inferior-tty}.
2591
2592@cindex inferior tty
2593@cindex set inferior controlling terminal
2594You can use the @code{show inferior-tty} command to tell @value{GDBN} to
2595display the name of the terminal that will be used for future runs of your
2596program.
2597
2598@table @code
0a1ddfa6 2599@item set inferior-tty [ @var{tty} ]
3cb3b8df 2600@kindex set inferior-tty
0a1ddfa6
SM
2601Set the tty for the program being debugged to @var{tty}. Omitting @var{tty}
2602restores the default behavior, which is to use the same terminal as
2603@value{GDBN}.
3cb3b8df
BR
2604
2605@item show inferior-tty
2606@kindex show inferior-tty
2607Show the current tty for the program being debugged.
2608@end table
c906108c 2609
6d2ebf8b 2610@node Attach
79a6e687 2611@section Debugging an Already-running Process
c906108c
SS
2612@kindex attach
2613@cindex attach
2614
2615@table @code
2616@item attach @var{process-id}
2617This command attaches to a running process---one that was started
2618outside @value{GDBN}. (@code{info files} shows your active
2619targets.) The command takes as argument a process ID. The usual way to
09d4efe1 2620find out the @var{process-id} of a Unix process is with the @code{ps} utility,
c906108c
SS
2621or with the @samp{jobs -l} shell command.
2622
2623@code{attach} does not repeat if you press @key{RET} a second time after
2624executing the command.
2625@end table
2626
2627To use @code{attach}, your program must be running in an environment
2628which supports processes; for example, @code{attach} does not work for
2629programs on bare-board targets that lack an operating system. You must
2630also have permission to send the process a signal.
2631
2632When you use @code{attach}, the debugger finds the program running in
2633the process first by looking in the current working directory, then (if
2634the program is not found) by using the source file search path
79a6e687 2635(@pxref{Source Path, ,Specifying Source Directories}). You can also use
c906108c
SS
2636the @code{file} command to load the program. @xref{Files, ,Commands to
2637Specify Files}.
2638
2639The first thing @value{GDBN} does after arranging to debug the specified
2640process is to stop it. You can examine and modify an attached process
53a5351d
JM
2641with all the @value{GDBN} commands that are ordinarily available when
2642you start processes with @code{run}. You can insert breakpoints; you
2643can step and continue; you can modify storage. If you would rather the
2644process continue running, you may use the @code{continue} command after
c906108c
SS
2645attaching @value{GDBN} to the process.
2646
2647@table @code
2648@kindex detach
2649@item detach
2650When you have finished debugging the attached process, you can use the
2651@code{detach} command to release it from @value{GDBN} control. Detaching
2652the process continues its execution. After the @code{detach} command,
2653that process and @value{GDBN} become completely independent once more, and you
2654are ready to @code{attach} another process or start one with @code{run}.
2655@code{detach} does not repeat if you press @key{RET} again after
2656executing the command.
2657@end table
2658
159fcc13
JK
2659If you exit @value{GDBN} while you have an attached process, you detach
2660that process. If you use the @code{run} command, you kill that process.
2661By default, @value{GDBN} asks for confirmation if you try to do either of these
2662things; you can control whether or not you need to confirm by using the
2663@code{set confirm} command (@pxref{Messages/Warnings, ,Optional Warnings and
79a6e687 2664Messages}).
c906108c 2665
6d2ebf8b 2666@node Kill Process
79a6e687 2667@section Killing the Child Process
c906108c
SS
2668
2669@table @code
2670@kindex kill
2671@item kill
2672Kill the child process in which your program is running under @value{GDBN}.
2673@end table
2674
2675This command is useful if you wish to debug a core dump instead of a
2676running process. @value{GDBN} ignores any core dump file while your program
2677is running.
2678
2679On some operating systems, a program cannot be executed outside @value{GDBN}
2680while you have breakpoints set on it inside @value{GDBN}. You can use the
2681@code{kill} command in this situation to permit running your program
2682outside the debugger.
2683
2684The @code{kill} command is also useful if you wish to recompile and
2685relink your program, since on many systems it is impossible to modify an
2686executable file while it is running in a process. In this case, when you
2687next type @code{run}, @value{GDBN} notices that the file has changed, and
2688reads the symbol table again (while trying to preserve your current
2689breakpoint settings).
2690
6c95b8df
PA
2691@node Inferiors and Programs
2692@section Debugging Multiple Inferiors and Programs
b77209e0 2693
6c95b8df
PA
2694@value{GDBN} lets you run and debug multiple programs in a single
2695session. In addition, @value{GDBN} on some systems may let you run
2696several programs simultaneously (otherwise you have to exit from one
2697before starting another). In the most general case, you can have
2698multiple threads of execution in each of multiple processes, launched
2699from multiple executables.
b77209e0
PA
2700
2701@cindex inferior
2702@value{GDBN} represents the state of each program execution with an
2703object called an @dfn{inferior}. An inferior typically corresponds to
2704a process, but is more general and applies also to targets that do not
2705have processes. Inferiors may be created before a process runs, and
6c95b8df
PA
2706may be retained after a process exits. Inferiors have unique
2707identifiers that are different from process ids. Usually each
2708inferior will also have its own distinct address space, although some
2709embedded targets may have several inferiors running in different parts
2710of a single address space. Each inferior may in turn have multiple
2711threads running in it.
b77209e0 2712
6c95b8df
PA
2713To find out what inferiors exist at any moment, use @w{@code{info
2714inferiors}}:
b77209e0
PA
2715
2716@table @code
a3c25011 2717@kindex info inferiors [ @var{id}@dots{} ]
b77209e0
PA
2718@item info inferiors
2719Print a list of all inferiors currently being managed by @value{GDBN}.
a3c25011
TT
2720By default all inferiors are printed, but the argument @var{id}@dots{}
2721-- a space separated list of inferior numbers -- can be used to limit
2722the display to just the requested inferiors.
3a1ff0b6
PA
2723
2724@value{GDBN} displays for each inferior (in this order):
2725
2726@enumerate
2727@item
2728the inferior number assigned by @value{GDBN}
2729
2730@item
2731the target system's inferior identifier
6c95b8df
PA
2732
2733@item
2734the name of the executable the inferior is running.
2735
3a1ff0b6
PA
2736@end enumerate
2737
2738@noindent
2739An asterisk @samp{*} preceding the @value{GDBN} inferior number
2740indicates the current inferior.
2741
2742For example,
2277426b 2743@end table
3a1ff0b6
PA
2744@c end table here to get a little more width for example
2745
2746@smallexample
2747(@value{GDBP}) info inferiors
6c95b8df
PA
2748 Num Description Executable
2749 2 process 2307 hello
2750* 1 process 3401 goodbye
3a1ff0b6 2751@end smallexample
2277426b
PA
2752
2753To switch focus between inferiors, use the @code{inferior} command:
2754
2755@table @code
3a1ff0b6
PA
2756@kindex inferior @var{infno}
2757@item inferior @var{infno}
2758Make inferior number @var{infno} the current inferior. The argument
2759@var{infno} is the inferior number assigned by @value{GDBN}, as shown
2760in the first field of the @samp{info inferiors} display.
2277426b
PA
2761@end table
2762
e3940304
PA
2763@vindex $_inferior@r{, convenience variable}
2764The debugger convenience variable @samp{$_inferior} contains the
2765number of the current inferior. You may find this useful in writing
2766breakpoint conditional expressions, command scripts, and so forth.
2767@xref{Convenience Vars,, Convenience Variables}, for general
2768information on convenience variables.
6c95b8df
PA
2769
2770You can get multiple executables into a debugging session via the
2771@code{add-inferior} and @w{@code{clone-inferior}} commands. On some
2772systems @value{GDBN} can add inferiors to the debug session
2773automatically by following calls to @code{fork} and @code{exec}. To
2774remove inferiors from the debugging session use the
af624141 2775@w{@code{remove-inferiors}} command.
6c95b8df
PA
2776
2777@table @code
2778@kindex add-inferior
2779@item add-inferior [ -copies @var{n} ] [ -exec @var{executable} ]
2780Adds @var{n} inferiors to be run using @var{executable} as the
697aa1b7 2781executable; @var{n} defaults to 1. If no executable is specified,
6c95b8df
PA
2782the inferiors begins empty, with no program. You can still assign or
2783change the program assigned to the inferior at any time by using the
2784@code{file} command with the executable name as its argument.
2785
2786@kindex clone-inferior
2787@item clone-inferior [ -copies @var{n} ] [ @var{infno} ]
2788Adds @var{n} inferiors ready to execute the same program as inferior
697aa1b7 2789@var{infno}; @var{n} defaults to 1, and @var{infno} defaults to the
6c95b8df
PA
2790number of the current inferior. This is a convenient command when you
2791want to run another instance of the inferior you are debugging.
2792
2793@smallexample
2794(@value{GDBP}) info inferiors
2795 Num Description Executable
2796* 1 process 29964 helloworld
2797(@value{GDBP}) clone-inferior
2798Added inferior 2.
27991 inferiors added.
2800(@value{GDBP}) info inferiors
2801 Num Description Executable
2802 2 <null> helloworld
2803* 1 process 29964 helloworld
2804@end smallexample
2805
2806You can now simply switch focus to inferior 2 and run it.
2807
af624141
MS
2808@kindex remove-inferiors
2809@item remove-inferiors @var{infno}@dots{}
2810Removes the inferior or inferiors @var{infno}@dots{}. It is not
2811possible to remove an inferior that is running with this command. For
2812those, use the @code{kill} or @code{detach} command first.
6c95b8df
PA
2813
2814@end table
2815
2816To quit debugging one of the running inferiors that is not the current
2817inferior, you can either detach from it by using the @w{@code{detach
2818inferior}} command (allowing it to run independently), or kill it
af624141 2819using the @w{@code{kill inferiors}} command:
2277426b
PA
2820
2821@table @code
af624141
MS
2822@kindex detach inferiors @var{infno}@dots{}
2823@item detach inferior @var{infno}@dots{}
2824Detach from the inferior or inferiors identified by @value{GDBN}
5e30da2c 2825inferior number(s) @var{infno}@dots{}. Note that the inferior's entry
af624141
MS
2826still stays on the list of inferiors shown by @code{info inferiors},
2827but its Description will show @samp{<null>}.
2828
2829@kindex kill inferiors @var{infno}@dots{}
2830@item kill inferiors @var{infno}@dots{}
2831Kill the inferior or inferiors identified by @value{GDBN} inferior
2832number(s) @var{infno}@dots{}. Note that the inferior's entry still
2833stays on the list of inferiors shown by @code{info inferiors}, but its
2834Description will show @samp{<null>}.
2277426b
PA
2835@end table
2836
6c95b8df 2837After the successful completion of a command such as @code{detach},
af624141 2838@code{detach inferiors}, @code{kill} or @code{kill inferiors}, or after
6c95b8df
PA
2839a normal process exit, the inferior is still valid and listed with
2840@code{info inferiors}, ready to be restarted.
2841
2842
2277426b
PA
2843To be notified when inferiors are started or exit under @value{GDBN}'s
2844control use @w{@code{set print inferior-events}}:
b77209e0 2845
2277426b 2846@table @code
b77209e0
PA
2847@kindex set print inferior-events
2848@cindex print messages on inferior start and exit
2849@item set print inferior-events
2850@itemx set print inferior-events on
2851@itemx set print inferior-events off
2852The @code{set print inferior-events} command allows you to enable or
2853disable printing of messages when @value{GDBN} notices that new
2854inferiors have started or that inferiors have exited or have been
2855detached. By default, these messages will not be printed.
2856
2857@kindex show print inferior-events
2858@item show print inferior-events
2859Show whether messages will be printed when @value{GDBN} detects that
2860inferiors have started, exited or have been detached.
2861@end table
2862
6c95b8df
PA
2863Many commands will work the same with multiple programs as with a
2864single program: e.g., @code{print myglobal} will simply display the
2865value of @code{myglobal} in the current inferior.
2866
2867
2868Occasionaly, when debugging @value{GDBN} itself, it may be useful to
2869get more info about the relationship of inferiors, programs, address
2870spaces in a debug session. You can do that with the @w{@code{maint
2871info program-spaces}} command.
2872
2873@table @code
2874@kindex maint info program-spaces
2875@item maint info program-spaces
2876Print a list of all program spaces currently being managed by
2877@value{GDBN}.
2878
2879@value{GDBN} displays for each program space (in this order):
2880
2881@enumerate
2882@item
2883the program space number assigned by @value{GDBN}
2884
2885@item
2886the name of the executable loaded into the program space, with e.g.,
2887the @code{file} command.
2888
2889@end enumerate
2890
2891@noindent
2892An asterisk @samp{*} preceding the @value{GDBN} program space number
2893indicates the current program space.
2894
2895In addition, below each program space line, @value{GDBN} prints extra
2896information that isn't suitable to display in tabular form. For
2897example, the list of inferiors bound to the program space.
2898
2899@smallexample
2900(@value{GDBP}) maint info program-spaces
2901 Id Executable
b05b1202 2902* 1 hello
6c95b8df
PA
2903 2 goodbye
2904 Bound inferiors: ID 1 (process 21561)
6c95b8df
PA
2905@end smallexample
2906
2907Here we can see that no inferior is running the program @code{hello},
2908while @code{process 21561} is running the program @code{goodbye}. On
2909some targets, it is possible that multiple inferiors are bound to the
2910same program space. The most common example is that of debugging both
2911the parent and child processes of a @code{vfork} call. For example,
2912
2913@smallexample
2914(@value{GDBP}) maint info program-spaces
2915 Id Executable
2916* 1 vfork-test
2917 Bound inferiors: ID 2 (process 18050), ID 1 (process 18045)
2918@end smallexample
2919
2920Here, both inferior 2 and inferior 1 are running in the same program
2921space as a result of inferior 1 having executed a @code{vfork} call.
2922@end table
2923
6d2ebf8b 2924@node Threads
79a6e687 2925@section Debugging Programs with Multiple Threads
c906108c
SS
2926
2927@cindex threads of execution
2928@cindex multiple threads
2929@cindex switching threads
b1236ac3 2930In some operating systems, such as GNU/Linux and Solaris, a single program
c906108c
SS
2931may have more than one @dfn{thread} of execution. The precise semantics
2932of threads differ from one operating system to another, but in general
2933the threads of a single program are akin to multiple processes---except
2934that they share one address space (that is, they can all examine and
2935modify the same variables). On the other hand, each thread has its own
2936registers and execution stack, and perhaps private memory.
2937
2938@value{GDBN} provides these facilities for debugging multi-thread
2939programs:
2940
2941@itemize @bullet
2942@item automatic notification of new threads
5d5658a1 2943@item @samp{thread @var{thread-id}}, a command to switch among threads
c906108c 2944@item @samp{info threads}, a command to inquire about existing threads
0a232300 2945@item @samp{thread apply [@var{thread-id-list} | all] @var{args}},
c906108c
SS
2946a command to apply a command to a list of threads
2947@item thread-specific breakpoints
93815fbf
VP
2948@item @samp{set print thread-events}, which controls printing of
2949messages on thread start and exit.
17a37d48
PP
2950@item @samp{set libthread-db-search-path @var{path}}, which lets
2951the user specify which @code{libthread_db} to use if the default choice
2952isn't compatible with the program.
c906108c
SS
2953@end itemize
2954
c906108c
SS
2955@cindex focus of debugging
2956@cindex current thread
2957The @value{GDBN} thread debugging facility allows you to observe all
2958threads while your program runs---but whenever @value{GDBN} takes
2959control, one thread in particular is always the focus of debugging.
2960This thread is called the @dfn{current thread}. Debugging commands show
2961program information from the perspective of the current thread.
2962
41afff9a 2963@cindex @code{New} @var{systag} message
c906108c
SS
2964@cindex thread identifier (system)
2965@c FIXME-implementors!! It would be more helpful if the [New...] message
2966@c included GDB's numeric thread handle, so you could just go to that
2967@c thread without first checking `info threads'.
2968Whenever @value{GDBN} detects a new thread in your program, it displays
2969the target system's identification for the thread with a message in the
697aa1b7 2970form @samp{[New @var{systag}]}, where @var{systag} is a thread identifier
c906108c 2971whose form varies depending on the particular system. For example, on
8807d78b 2972@sc{gnu}/Linux, you might see
c906108c 2973
474c8240 2974@smallexample
08e796bc 2975[New Thread 0x41e02940 (LWP 25582)]
474c8240 2976@end smallexample
c906108c
SS
2977
2978@noindent
b1236ac3 2979when @value{GDBN} notices a new thread. In contrast, on other systems,
c906108c
SS
2980the @var{systag} is simply something like @samp{process 368}, with no
2981further qualifier.
2982
2983@c FIXME!! (1) Does the [New...] message appear even for the very first
2984@c thread of a program, or does it only appear for the
6ca652b0 2985@c second---i.e.@: when it becomes obvious we have a multithread
c906108c
SS
2986@c program?
2987@c (2) *Is* there necessarily a first thread always? Or do some
2988@c multithread systems permit starting a program with multiple
5d161b24 2989@c threads ab initio?
c906108c 2990
5d5658a1
PA
2991@anchor{thread numbers}
2992@cindex thread number, per inferior
c906108c 2993@cindex thread identifier (GDB)
5d5658a1
PA
2994For debugging purposes, @value{GDBN} associates its own thread number
2995---always a single integer---with each thread of an inferior. This
2996number is unique between all threads of an inferior, but not unique
2997between threads of different inferiors.
2998
2999@cindex qualified thread ID
3000You can refer to a given thread in an inferior using the qualified
3001@var{inferior-num}.@var{thread-num} syntax, also known as
3002@dfn{qualified thread ID}, with @var{inferior-num} being the inferior
3003number and @var{thread-num} being the thread number of the given
3004inferior. For example, thread @code{2.3} refers to thread number 3 of
3005inferior 2. If you omit @var{inferior-num} (e.g., @code{thread 3}),
3006then @value{GDBN} infers you're referring to a thread of the current
3007inferior.
3008
3009Until you create a second inferior, @value{GDBN} does not show the
3010@var{inferior-num} part of thread IDs, even though you can always use
3011the full @var{inferior-num}.@var{thread-num} form to refer to threads
3012of inferior 1, the initial inferior.
3013
3014@anchor{thread ID lists}
3015@cindex thread ID lists
3016Some commands accept a space-separated @dfn{thread ID list} as
71ef29a8
PA
3017argument. A list element can be:
3018
3019@enumerate
3020@item
3021A thread ID as shown in the first field of the @samp{info threads}
3022display, with or without an inferior qualifier. E.g., @samp{2.1} or
3023@samp{1}.
3024
3025@item
3026A range of thread numbers, again with or without an inferior
3027qualifier, as in @var{inf}.@var{thr1}-@var{thr2} or
3028@var{thr1}-@var{thr2}. E.g., @samp{1.2-4} or @samp{2-4}.
3029
3030@item
3031All threads of an inferior, specified with a star wildcard, with or
3032without an inferior qualifier, as in @var{inf}.@code{*} (e.g.,
3033@samp{1.*}) or @code{*}. The former refers to all threads of the
3034given inferior, and the latter form without an inferior qualifier
3035refers to all threads of the current inferior.
3036
3037@end enumerate
3038
3039For example, if the current inferior is 1, and inferior 7 has one
3040thread with ID 7.1, the thread list @samp{1 2-3 4.5 6.7-9 7.*}
3041includes threads 1 to 3 of inferior 1, thread 5 of inferior 4, threads
30427 to 9 of inferior 6 and all threads of inferior 7. That is, in
3043expanded qualified form, the same as @samp{1.1 1.2 1.3 4.5 6.7 6.8 6.9
30447.1}.
3045
5d5658a1
PA
3046
3047@anchor{global thread numbers}
3048@cindex global thread number
3049@cindex global thread identifier (GDB)
3050In addition to a @emph{per-inferior} number, each thread is also
3051assigned a unique @emph{global} number, also known as @dfn{global
3052thread ID}, a single integer. Unlike the thread number component of
3053the thread ID, no two threads have the same global ID, even when
3054you're debugging multiple inferiors.
c906108c 3055
f4f4330e
PA
3056From @value{GDBN}'s perspective, a process always has at least one
3057thread. In other words, @value{GDBN} assigns a thread number to the
3058program's ``main thread'' even if the program is not multi-threaded.
3059
5d5658a1 3060@vindex $_thread@r{, convenience variable}
663f6d42
PA
3061@vindex $_gthread@r{, convenience variable}
3062The debugger convenience variables @samp{$_thread} and
3063@samp{$_gthread} contain, respectively, the per-inferior thread number
3064and the global thread number of the current thread. You may find this
5d5658a1
PA
3065useful in writing breakpoint conditional expressions, command scripts,
3066and so forth. @xref{Convenience Vars,, Convenience Variables}, for
3067general information on convenience variables.
3068
f303dbd6
PA
3069If @value{GDBN} detects the program is multi-threaded, it augments the
3070usual message about stopping at a breakpoint with the ID and name of
3071the thread that hit the breakpoint.
3072
3073@smallexample
3074Thread 2 "client" hit Breakpoint 1, send_message () at client.c:68
3075@end smallexample
3076
3077Likewise when the program receives a signal:
3078
3079@smallexample
3080Thread 1 "main" received signal SIGINT, Interrupt.
3081@end smallexample
3082
c906108c
SS
3083@table @code
3084@kindex info threads
5d5658a1
PA
3085@item info threads @r{[}@var{thread-id-list}@r{]}
3086
3087Display information about one or more threads. With no arguments
3088displays information about all threads. You can specify the list of
3089threads that you want to display using the thread ID list syntax
3090(@pxref{thread ID lists}).
3091
60f98dde 3092@value{GDBN} displays for each thread (in this order):
c906108c
SS
3093
3094@enumerate
09d4efe1 3095@item
5d5658a1 3096the per-inferior thread number assigned by @value{GDBN}
c906108c 3097
c84f6bbf
PA
3098@item
3099the global thread number assigned by @value{GDBN}, if the @samp{-gid}
3100option was specified
3101
09d4efe1
EZ
3102@item
3103the target system's thread identifier (@var{systag})
c906108c 3104
4694da01
TT
3105@item
3106the thread's name, if one is known. A thread can either be named by
3107the user (see @code{thread name}, below), or, in some cases, by the
3108program itself.
3109
09d4efe1
EZ
3110@item
3111the current stack frame summary for that thread
c906108c
SS
3112@end enumerate
3113
3114@noindent
3115An asterisk @samp{*} to the left of the @value{GDBN} thread number
3116indicates the current thread.
3117
5d161b24 3118For example,
c906108c
SS
3119@end table
3120@c end table here to get a little more width for example
3121
3122@smallexample
3123(@value{GDBP}) info threads
13fd8b81 3124 Id Target Id Frame
c0ecb95f 3125* 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8)
b05b1202
PA
3126 2 process 35 thread 23 0x34e5 in sigpause ()
3127 3 process 35 thread 27 0x34e5 in sigpause ()
c906108c
SS
3128 at threadtest.c:68
3129@end smallexample
53a5351d 3130
5d5658a1
PA
3131If you're debugging multiple inferiors, @value{GDBN} displays thread
3132IDs using the qualified @var{inferior-num}.@var{thread-num} format.
c84f6bbf
PA
3133Otherwise, only @var{thread-num} is shown.
3134
3135If you specify the @samp{-gid} option, @value{GDBN} displays a column
3136indicating each thread's global thread ID:
5d5658a1
PA
3137
3138@smallexample
3139(@value{GDBP}) info threads
c84f6bbf
PA
3140 Id GId Target Id Frame
3141 1.1 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8)
3142 1.2 3 process 35 thread 23 0x34e5 in sigpause ()
3143 1.3 4 process 35 thread 27 0x34e5 in sigpause ()
3144* 2.1 2 process 65 thread 1 main (argc=1, argv=0x7ffffff8)
5d5658a1
PA
3145@end smallexample
3146
c45da7e6
EZ
3147On Solaris, you can display more information about user threads with a
3148Solaris-specific command:
3149
3150@table @code
3151@item maint info sol-threads
3152@kindex maint info sol-threads
3153@cindex thread info (Solaris)
3154Display info on Solaris user threads.
3155@end table
3156
c906108c 3157@table @code
5d5658a1
PA
3158@kindex thread @var{thread-id}
3159@item thread @var{thread-id}
3160Make thread ID @var{thread-id} the current thread. The command
3161argument @var{thread-id} is the @value{GDBN} thread ID, as shown in
3162the first field of the @samp{info threads} display, with or without an
3163inferior qualifier (e.g., @samp{2.1} or @samp{1}).
3164
3165@value{GDBN} responds by displaying the system identifier of the
3166thread you selected, and its current stack frame summary:
c906108c
SS
3167
3168@smallexample
c906108c 3169(@value{GDBP}) thread 2
13fd8b81
TT
3170[Switching to thread 2 (Thread 0xb7fdab70 (LWP 12747))]
3171#0 some_function (ignore=0x0) at example.c:8
31728 printf ("hello\n");
c906108c
SS
3173@end smallexample
3174
3175@noindent
3176As with the @samp{[New @dots{}]} message, the form of the text after
3177@samp{Switching to} depends on your system's conventions for identifying
5d161b24 3178threads.
c906108c 3179
9c16f35a 3180@kindex thread apply
638ac427 3181@cindex apply command to several threads
0a232300 3182@item thread apply [@var{thread-id-list} | all [-ascending]] [@var{flag}]@dots{} @var{command}
839c27b7 3183The @code{thread apply} command allows you to apply the named
5d5658a1
PA
3184@var{command} to one or more threads. Specify the threads that you
3185want affected using the thread ID list syntax (@pxref{thread ID
3186lists}), or specify @code{all} to apply to all threads. To apply a
3187command to all threads in descending order, type @kbd{thread apply all
253828f1
JK
3188@var{command}}. To apply a command to all threads in ascending order,
3189type @kbd{thread apply all -ascending @var{command}}.
3190
0a232300
PW
3191The @var{flag} arguments control what output to produce and how to handle
3192errors raised when applying @var{command} to a thread. @var{flag}
3193must start with a @code{-} directly followed by one letter in
3194@code{qcs}. If several flags are provided, they must be given
3195individually, such as @code{-c -q}.
3196
3197By default, @value{GDBN} displays some thread information before the
3198output produced by @var{command}, and an error raised during the
3199execution of a @var{command} will abort @code{thread apply}. The
3200following flags can be used to fine-tune this behavior:
3201
3202@table @code
3203@item -c
3204The flag @code{-c}, which stands for @samp{continue}, causes any
3205errors in @var{command} to be displayed, and the execution of
3206@code{thread apply} then continues.
3207@item -s
3208The flag @code{-s}, which stands for @samp{silent}, causes any errors
3209or empty output produced by a @var{command} to be silently ignored.
3210That is, the execution continues, but the thread information and errors
3211are not printed.
3212@item -q
3213The flag @code{-q} (@samp{quiet}) disables printing the thread
3214information.
3215@end table
3216
3217Flags @code{-c} and @code{-s} cannot be used together.
3218
3219@kindex taas
3220@cindex apply command to all threads (ignoring errors and empty output)
3221@item taas @var{command}
3222Shortcut for @code{thread apply all -s @var{command}}.
3223Applies @var{command} on all threads, ignoring errors and empty output.
3224
3225@kindex tfaas
3226@cindex apply a command to all frames of all threads (ignoring errors and empty output)
3227@item tfaas @var{command}
3228Shortcut for @code{thread apply all -s frame apply all -s @var{command}}.
3229Applies @var{command} on all frames of all threads, ignoring errors
3230and empty output. Note that the flag @code{-s} is specified twice:
3231The first @code{-s} ensures that @code{thread apply} only shows the thread
3232information of the threads for which @code{frame apply} produces
3233some output. The second @code{-s} is needed to ensure that @code{frame
3234apply} shows the frame information of a frame only if the
3235@var{command} successfully produced some output.
3236
3237It can for example be used to print a local variable or a function
3238argument without knowing the thread or frame where this variable or argument
3239is, using:
3240@smallexample
3241(@value{GDBP}) tfaas p some_local_var_i_do_not_remember_where_it_is
3242@end smallexample
3243
93815fbf 3244
4694da01
TT
3245@kindex thread name
3246@cindex name a thread
3247@item thread name [@var{name}]
3248This command assigns a name to the current thread. If no argument is
3249given, any existing user-specified name is removed. The thread name
3250appears in the @samp{info threads} display.
3251
3252On some systems, such as @sc{gnu}/Linux, @value{GDBN} is able to
3253determine the name of the thread as given by the OS. On these
3254systems, a name specified with @samp{thread name} will override the
3255system-give name, and removing the user-specified name will cause
3256@value{GDBN} to once again display the system-specified name.
3257
60f98dde
MS
3258@kindex thread find
3259@cindex search for a thread
3260@item thread find [@var{regexp}]
3261Search for and display thread ids whose name or @var{systag}
3262matches the supplied regular expression.
3263
3264As well as being the complement to the @samp{thread name} command,
3265this command also allows you to identify a thread by its target
3266@var{systag}. For instance, on @sc{gnu}/Linux, the target @var{systag}
3267is the LWP id.
3268
3269@smallexample
3270(@value{GDBN}) thread find 26688
3271Thread 4 has target id 'Thread 0x41e02940 (LWP 26688)'
3272(@value{GDBN}) info thread 4
3273 Id Target Id Frame
3274 4 Thread 0x41e02940 (LWP 26688) 0x00000031ca6cd372 in select ()
3275@end smallexample
3276
93815fbf
VP
3277@kindex set print thread-events
3278@cindex print messages on thread start and exit
3279@item set print thread-events
3280@itemx set print thread-events on
3281@itemx set print thread-events off
3282The @code{set print thread-events} command allows you to enable or
3283disable printing of messages when @value{GDBN} notices that new threads have
3284started or that threads have exited. By default, these messages will
3285be printed if detection of these events is supported by the target.
3286Note that these messages cannot be disabled on all targets.
3287
3288@kindex show print thread-events
3289@item show print thread-events
3290Show whether messages will be printed when @value{GDBN} detects that threads
3291have started and exited.
c906108c
SS
3292@end table
3293
79a6e687 3294@xref{Thread Stops,,Stopping and Starting Multi-thread Programs}, for
c906108c
SS
3295more information about how @value{GDBN} behaves when you stop and start
3296programs with multiple threads.
3297
79a6e687 3298@xref{Set Watchpoints,,Setting Watchpoints}, for information about
c906108c 3299watchpoints in programs with multiple threads.
c906108c 3300
bf88dd68 3301@anchor{set libthread-db-search-path}
17a37d48
PP
3302@table @code
3303@kindex set libthread-db-search-path
3304@cindex search path for @code{libthread_db}
3305@item set libthread-db-search-path @r{[}@var{path}@r{]}
3306If this variable is set, @var{path} is a colon-separated list of
3307directories @value{GDBN} will use to search for @code{libthread_db}.
3308If you omit @var{path}, @samp{libthread-db-search-path} will be reset to
98a5dd13 3309its default value (@code{$sdir:$pdir} on @sc{gnu}/Linux and Solaris systems).
7e0396aa
DE
3310Internally, the default value comes from the @code{LIBTHREAD_DB_SEARCH_PATH}
3311macro.
17a37d48
PP
3312
3313On @sc{gnu}/Linux and Solaris systems, @value{GDBN} uses a ``helper''
3314@code{libthread_db} library to obtain information about threads in the
3315inferior process. @value{GDBN} will use @samp{libthread-db-search-path}
bf88dd68
JK
3316to find @code{libthread_db}. @value{GDBN} also consults first if inferior
3317specific thread debugging library loading is enabled
3318by @samp{set auto-load libthread-db} (@pxref{libthread_db.so.1 file}).
98a5dd13
DE
3319
3320A special entry @samp{$sdir} for @samp{libthread-db-search-path}
3321refers to the default system directories that are
bf88dd68
JK
3322normally searched for loading shared libraries. The @samp{$sdir} entry
3323is the only kind not needing to be enabled by @samp{set auto-load libthread-db}
3324(@pxref{libthread_db.so.1 file}).
98a5dd13
DE
3325
3326A special entry @samp{$pdir} for @samp{libthread-db-search-path}
3327refers to the directory from which @code{libpthread}
3328was loaded in the inferior process.
17a37d48
PP
3329
3330For any @code{libthread_db} library @value{GDBN} finds in above directories,
3331@value{GDBN} attempts to initialize it with the current inferior process.
3332If this initialization fails (which could happen because of a version
3333mismatch between @code{libthread_db} and @code{libpthread}), @value{GDBN}
3334will unload @code{libthread_db}, and continue with the next directory.
3335If none of @code{libthread_db} libraries initialize successfully,
3336@value{GDBN} will issue a warning and thread debugging will be disabled.
3337
3338Setting @code{libthread-db-search-path} is currently implemented
3339only on some platforms.
3340
3341@kindex show libthread-db-search-path
3342@item show libthread-db-search-path
3343Display current libthread_db search path.
02d868e8
PP
3344
3345@kindex set debug libthread-db
3346@kindex show debug libthread-db
3347@cindex debugging @code{libthread_db}
3348@item set debug libthread-db
3349@itemx show debug libthread-db
3350Turns on or off display of @code{libthread_db}-related events.
3351Use @code{1} to enable, @code{0} to disable.
17a37d48
PP
3352@end table
3353
6c95b8df
PA
3354@node Forks
3355@section Debugging Forks
c906108c
SS
3356
3357@cindex fork, debugging programs which call
3358@cindex multiple processes
3359@cindex processes, multiple
53a5351d
JM
3360On most systems, @value{GDBN} has no special support for debugging
3361programs which create additional processes using the @code{fork}
3362function. When a program forks, @value{GDBN} will continue to debug the
3363parent process and the child process will run unimpeded. If you have
3364set a breakpoint in any code which the child then executes, the child
3365will get a @code{SIGTRAP} signal which (unless it catches the signal)
3366will cause it to terminate.
c906108c
SS
3367
3368However, if you want to debug the child process there is a workaround
3369which isn't too painful. Put a call to @code{sleep} in the code which
3370the child process executes after the fork. It may be useful to sleep
3371only if a certain environment variable is set, or a certain file exists,
3372so that the delay need not occur when you don't want to run @value{GDBN}
3373on the child. While the child is sleeping, use the @code{ps} program to
3374get its process ID. Then tell @value{GDBN} (a new invocation of
3375@value{GDBN} if you are also debugging the parent process) to attach to
d4f3574e 3376the child process (@pxref{Attach}). From that point on you can debug
c906108c 3377the child process just like any other process which you attached to.
c906108c 3378
b1236ac3
PA
3379On some systems, @value{GDBN} provides support for debugging programs
3380that create additional processes using the @code{fork} or @code{vfork}
3381functions. On @sc{gnu}/Linux platforms, this feature is supported
19d9d4ef 3382with kernel version 2.5.46 and later.
c906108c 3383
19d9d4ef
DB
3384The fork debugging commands are supported in native mode and when
3385connected to @code{gdbserver} in either @code{target remote} mode or
3386@code{target extended-remote} mode.
0d71eef5 3387
c906108c
SS
3388By default, when a program forks, @value{GDBN} will continue to debug
3389the parent process and the child process will run unimpeded.
3390
3391If you want to follow the child process instead of the parent process,
3392use the command @w{@code{set follow-fork-mode}}.
3393
3394@table @code
3395@kindex set follow-fork-mode
3396@item set follow-fork-mode @var{mode}
3397Set the debugger response to a program call of @code{fork} or
3398@code{vfork}. A call to @code{fork} or @code{vfork} creates a new
9c16f35a 3399process. The @var{mode} argument can be:
c906108c
SS
3400
3401@table @code
3402@item parent
3403The original process is debugged after a fork. The child process runs
2df3850c 3404unimpeded. This is the default.
c906108c
SS
3405
3406@item child
3407The new process is debugged after a fork. The parent process runs
3408unimpeded.
3409
c906108c
SS
3410@end table
3411
9c16f35a 3412@kindex show follow-fork-mode
c906108c 3413@item show follow-fork-mode
2df3850c 3414Display the current debugger response to a @code{fork} or @code{vfork} call.
c906108c
SS
3415@end table
3416
5c95884b
MS
3417@cindex debugging multiple processes
3418On Linux, if you want to debug both the parent and child processes, use the
3419command @w{@code{set detach-on-fork}}.
3420
3421@table @code
3422@kindex set detach-on-fork
3423@item set detach-on-fork @var{mode}
3424Tells gdb whether to detach one of the processes after a fork, or
3425retain debugger control over them both.
3426
3427@table @code
3428@item on
3429The child process (or parent process, depending on the value of
3430@code{follow-fork-mode}) will be detached and allowed to run
3431independently. This is the default.
3432
3433@item off
3434Both processes will be held under the control of @value{GDBN}.
3435One process (child or parent, depending on the value of
3436@code{follow-fork-mode}) is debugged as usual, while the other
3437is held suspended.
3438
3439@end table
3440
11310833
NR
3441@kindex show detach-on-fork
3442@item show detach-on-fork
3443Show whether detach-on-fork mode is on/off.
5c95884b
MS
3444@end table
3445
2277426b
PA
3446If you choose to set @samp{detach-on-fork} mode off, then @value{GDBN}
3447will retain control of all forked processes (including nested forks).
3448You can list the forked processes under the control of @value{GDBN} by
3449using the @w{@code{info inferiors}} command, and switch from one fork
6c95b8df
PA
3450to another by using the @code{inferior} command (@pxref{Inferiors and
3451Programs, ,Debugging Multiple Inferiors and Programs}).
5c95884b
MS
3452
3453To quit debugging one of the forked processes, you can either detach
af624141
MS
3454from it by using the @w{@code{detach inferiors}} command (allowing it
3455to run independently), or kill it using the @w{@code{kill inferiors}}
6c95b8df
PA
3456command. @xref{Inferiors and Programs, ,Debugging Multiple Inferiors
3457and Programs}.
5c95884b 3458
c906108c
SS
3459If you ask to debug a child process and a @code{vfork} is followed by an
3460@code{exec}, @value{GDBN} executes the new target up to the first
3461breakpoint in the new target. If you have a breakpoint set on
3462@code{main} in your original program, the breakpoint will also be set on
3463the child process's @code{main}.
3464
2277426b
PA
3465On some systems, when a child process is spawned by @code{vfork}, you
3466cannot debug the child or parent until an @code{exec} call completes.
c906108c
SS
3467
3468If you issue a @code{run} command to @value{GDBN} after an @code{exec}
6c95b8df
PA
3469call executes, the new target restarts. To restart the parent
3470process, use the @code{file} command with the parent executable name
3471as its argument. By default, after an @code{exec} call executes,
3472@value{GDBN} discards the symbols of the previous executable image.
3473You can change this behaviour with the @w{@code{set follow-exec-mode}}
3474command.
3475
3476@table @code
3477@kindex set follow-exec-mode
3478@item set follow-exec-mode @var{mode}
3479
3480Set debugger response to a program call of @code{exec}. An
3481@code{exec} call replaces the program image of a process.
3482
3483@code{follow-exec-mode} can be:
3484
3485@table @code
3486@item new
3487@value{GDBN} creates a new inferior and rebinds the process to this
3488new inferior. The program the process was running before the
3489@code{exec} call can be restarted afterwards by restarting the
3490original inferior.
3491
3492For example:
3493
3494@smallexample
3495(@value{GDBP}) info inferiors
3496(gdb) info inferior
3497 Id Description Executable
3498* 1 <null> prog1
3499(@value{GDBP}) run
3500process 12020 is executing new program: prog2
3501Program exited normally.
3502(@value{GDBP}) info inferiors
3503 Id Description Executable
c0ecb95f 3504 1 <null> prog1
b05b1202 3505* 2 <null> prog2
6c95b8df
PA
3506@end smallexample
3507
3508@item same
3509@value{GDBN} keeps the process bound to the same inferior. The new
3510executable image replaces the previous executable loaded in the
3511inferior. Restarting the inferior after the @code{exec} call, with
3512e.g., the @code{run} command, restarts the executable the process was
3513running after the @code{exec} call. This is the default mode.
3514
3515For example:
3516
3517@smallexample
3518(@value{GDBP}) info inferiors
3519 Id Description Executable
3520* 1 <null> prog1
3521(@value{GDBP}) run
3522process 12020 is executing new program: prog2
3523Program exited normally.
3524(@value{GDBP}) info inferiors
3525 Id Description Executable
3526* 1 <null> prog2
3527@end smallexample
3528
3529@end table
3530@end table
c906108c 3531
19d9d4ef
DB
3532@code{follow-exec-mode} is supported in native mode and
3533@code{target extended-remote} mode.
3534
c906108c
SS
3535You can use the @code{catch} command to make @value{GDBN} stop whenever
3536a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set
79a6e687 3537Catchpoints, ,Setting Catchpoints}.
c906108c 3538
5c95884b 3539@node Checkpoint/Restart
79a6e687 3540@section Setting a @emph{Bookmark} to Return to Later
5c95884b
MS
3541
3542@cindex checkpoint
3543@cindex restart
3544@cindex bookmark
3545@cindex snapshot of a process
3546@cindex rewind program state
3547
3548On certain operating systems@footnote{Currently, only
3549@sc{gnu}/Linux.}, @value{GDBN} is able to save a @dfn{snapshot} of a
3550program's state, called a @dfn{checkpoint}, and come back to it
3551later.
3552
3553Returning to a checkpoint effectively undoes everything that has
3554happened in the program since the @code{checkpoint} was saved. This
3555includes changes in memory, registers, and even (within some limits)
3556system state. Effectively, it is like going back in time to the
3557moment when the checkpoint was saved.
3558
3559Thus, if you're stepping thru a program and you think you're
3560getting close to the point where things go wrong, you can save
3561a checkpoint. Then, if you accidentally go too far and miss
3562the critical statement, instead of having to restart your program
3563from the beginning, you can just go back to the checkpoint and
3564start again from there.
3565
3566This can be especially useful if it takes a lot of time or
3567steps to reach the point where you think the bug occurs.
3568
3569To use the @code{checkpoint}/@code{restart} method of debugging:
3570
3571@table @code
3572@kindex checkpoint
3573@item checkpoint
3574Save a snapshot of the debugged program's current execution state.
3575The @code{checkpoint} command takes no arguments, but each checkpoint
3576is assigned a small integer id, similar to a breakpoint id.
3577
3578@kindex info checkpoints
3579@item info checkpoints
3580List the checkpoints that have been saved in the current debugging
3581session. For each checkpoint, the following information will be
3582listed:
3583
3584@table @code
3585@item Checkpoint ID
3586@item Process ID
3587@item Code Address
3588@item Source line, or label
3589@end table
3590
3591@kindex restart @var{checkpoint-id}
3592@item restart @var{checkpoint-id}
3593Restore the program state that was saved as checkpoint number
3594@var{checkpoint-id}. All program variables, registers, stack frames
3595etc.@: will be returned to the values that they had when the checkpoint
3596was saved. In essence, gdb will ``wind back the clock'' to the point
3597in time when the checkpoint was saved.
3598
3599Note that breakpoints, @value{GDBN} variables, command history etc.
3600are not affected by restoring a checkpoint. In general, a checkpoint
3601only restores things that reside in the program being debugged, not in
3602the debugger.
3603
b8db102d
MS
3604@kindex delete checkpoint @var{checkpoint-id}
3605@item delete checkpoint @var{checkpoint-id}
5c95884b
MS
3606Delete the previously-saved checkpoint identified by @var{checkpoint-id}.
3607
3608@end table
3609
3610Returning to a previously saved checkpoint will restore the user state
3611of the program being debugged, plus a significant subset of the system
3612(OS) state, including file pointers. It won't ``un-write'' data from
3613a file, but it will rewind the file pointer to the previous location,
3614so that the previously written data can be overwritten. For files
3615opened in read mode, the pointer will also be restored so that the
3616previously read data can be read again.
3617
3618Of course, characters that have been sent to a printer (or other
3619external device) cannot be ``snatched back'', and characters received
3620from eg.@: a serial device can be removed from internal program buffers,
3621but they cannot be ``pushed back'' into the serial pipeline, ready to
3622be received again. Similarly, the actual contents of files that have
3623been changed cannot be restored (at this time).
3624
3625However, within those constraints, you actually can ``rewind'' your
3626program to a previously saved point in time, and begin debugging it
3627again --- and you can change the course of events so as to debug a
3628different execution path this time.
3629
3630@cindex checkpoints and process id
3631Finally, there is one bit of internal program state that will be
3632different when you return to a checkpoint --- the program's process
3633id. Each checkpoint will have a unique process id (or @var{pid}),
3634and each will be different from the program's original @var{pid}.
3635If your program has saved a local copy of its process id, this could
3636potentially pose a problem.
3637
79a6e687 3638@subsection A Non-obvious Benefit of Using Checkpoints
5c95884b
MS
3639
3640On some systems such as @sc{gnu}/Linux, address space randomization
3641is performed on new processes for security reasons. This makes it
3642difficult or impossible to set a breakpoint, or watchpoint, on an
3643absolute address if you have to restart the program, since the
3644absolute location of a symbol will change from one execution to the
3645next.
3646
3647A checkpoint, however, is an @emph{identical} copy of a process.
3648Therefore if you create a checkpoint at (eg.@:) the start of main,
3649and simply return to that checkpoint instead of restarting the
3650process, you can avoid the effects of address randomization and
3651your symbols will all stay in the same place.
3652
6d2ebf8b 3653@node Stopping
c906108c
SS
3654@chapter Stopping and Continuing
3655
3656The principal purposes of using a debugger are so that you can stop your
3657program before it terminates; or so that, if your program runs into
3658trouble, you can investigate and find out why.
3659
7a292a7a
SS
3660Inside @value{GDBN}, your program may stop for any of several reasons,
3661such as a signal, a breakpoint, or reaching a new line after a
3662@value{GDBN} command such as @code{step}. You may then examine and
3663change variables, set new breakpoints or remove old ones, and then
3664continue execution. Usually, the messages shown by @value{GDBN} provide
3665ample explanation of the status of your program---but you can also
3666explicitly request this information at any time.
c906108c
SS
3667
3668@table @code
3669@kindex info program
3670@item info program
3671Display information about the status of your program: whether it is
7a292a7a 3672running or not, what process it is, and why it stopped.
c906108c
SS
3673@end table
3674
3675@menu
3676* Breakpoints:: Breakpoints, watchpoints, and catchpoints
3677* Continuing and Stepping:: Resuming execution
aad1c02c
TT
3678* Skipping Over Functions and Files::
3679 Skipping over functions and files
c906108c 3680* Signals:: Signals
c906108c 3681* Thread Stops:: Stopping and starting multi-thread programs
c906108c
SS
3682@end menu
3683
6d2ebf8b 3684@node Breakpoints
79a6e687 3685@section Breakpoints, Watchpoints, and Catchpoints
c906108c
SS
3686
3687@cindex breakpoints
3688A @dfn{breakpoint} makes your program stop whenever a certain point in
3689the program is reached. For each breakpoint, you can add conditions to
3690control in finer detail whether your program stops. You can set
3691breakpoints with the @code{break} command and its variants (@pxref{Set
79a6e687 3692Breaks, ,Setting Breakpoints}), to specify the place where your program
c906108c
SS
3693should stop by line number, function name or exact address in the
3694program.
3695
09d4efe1 3696On some systems, you can set breakpoints in shared libraries before
b1236ac3 3697the executable is run.
c906108c
SS
3698
3699@cindex watchpoints
fd60e0df 3700@cindex data breakpoints
c906108c
SS
3701@cindex memory tracing
3702@cindex breakpoint on memory address
3703@cindex breakpoint on variable modification
3704A @dfn{watchpoint} is a special breakpoint that stops your program
fd60e0df 3705when the value of an expression changes. The expression may be a value
0ced0c34 3706of a variable, or it could involve values of one or more variables
fd60e0df
EZ
3707combined by operators, such as @samp{a + b}. This is sometimes called
3708@dfn{data breakpoints}. You must use a different command to set
79a6e687 3709watchpoints (@pxref{Set Watchpoints, ,Setting Watchpoints}), but aside
fd60e0df
EZ
3710from that, you can manage a watchpoint like any other breakpoint: you
3711enable, disable, and delete both breakpoints and watchpoints using the
3712same commands.
c906108c
SS
3713
3714You can arrange to have values from your program displayed automatically
3715whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,,
79a6e687 3716Automatic Display}.
c906108c
SS
3717
3718@cindex catchpoints
3719@cindex breakpoint on events
3720A @dfn{catchpoint} is another special breakpoint that stops your program
b37052ae 3721when a certain kind of event occurs, such as the throwing of a C@t{++}
c906108c
SS
3722exception or the loading of a library. As with watchpoints, you use a
3723different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting
79a6e687 3724Catchpoints}), but aside from that, you can manage a catchpoint like any
c906108c 3725other breakpoint. (To stop when your program receives a signal, use the
d4f3574e 3726@code{handle} command; see @ref{Signals, ,Signals}.)
c906108c
SS
3727
3728@cindex breakpoint numbers
3729@cindex numbers for breakpoints
3730@value{GDBN} assigns a number to each breakpoint, watchpoint, or
3731catchpoint when you create it; these numbers are successive integers
3732starting with one. In many of the commands for controlling various
3733features of breakpoints you use the breakpoint number to say which
3734breakpoint you want to change. Each breakpoint may be @dfn{enabled} or
3735@dfn{disabled}; if disabled, it has no effect on your program until you
3736enable it again.
3737
c5394b80 3738@cindex breakpoint ranges
18da0c51 3739@cindex breakpoint lists
c5394b80 3740@cindex ranges of breakpoints
18da0c51
MG
3741@cindex lists of breakpoints
3742Some @value{GDBN} commands accept a space-separated list of breakpoints
3743on which to operate. A list element can be either a single breakpoint number,
3744like @samp{5}, or a range of such numbers, like @samp{5-7}.
3745When a breakpoint list is given to a command, all breakpoints in that list
3746are operated on.
c5394b80 3747
c906108c
SS
3748@menu
3749* Set Breaks:: Setting breakpoints
3750* Set Watchpoints:: Setting watchpoints
3751* Set Catchpoints:: Setting catchpoints
3752* Delete Breaks:: Deleting breakpoints
3753* Disabling:: Disabling breakpoints
3754* Conditions:: Break conditions
3755* Break Commands:: Breakpoint command lists
e7e0cddf 3756* Dynamic Printf:: Dynamic printf
6149aea9 3757* Save Breakpoints:: How to save breakpoints in a file
62e5f89c 3758* Static Probe Points:: Listing static probe points
d4f3574e 3759* Error in Breakpoints:: ``Cannot insert breakpoints''
79a6e687 3760* Breakpoint-related Warnings:: ``Breakpoint address adjusted...''
c906108c
SS
3761@end menu
3762
6d2ebf8b 3763@node Set Breaks
79a6e687 3764@subsection Setting Breakpoints
c906108c 3765
5d161b24 3766@c FIXME LMB what does GDB do if no code on line of breakpt?
c906108c
SS
3767@c consider in particular declaration with/without initialization.
3768@c
3769@c FIXME 2 is there stuff on this already? break at fun start, already init?
3770
3771@kindex break
41afff9a
EZ
3772@kindex b @r{(@code{break})}
3773@vindex $bpnum@r{, convenience variable}
c906108c
SS
3774@cindex latest breakpoint
3775Breakpoints are set with the @code{break} command (abbreviated
5d161b24 3776@code{b}). The debugger convenience variable @samp{$bpnum} records the
f3b28801 3777number of the breakpoint you've set most recently; see @ref{Convenience
79a6e687 3778Vars,, Convenience Variables}, for a discussion of what you can do with
c906108c
SS
3779convenience variables.
3780
c906108c 3781@table @code
2a25a5ba
EZ
3782@item break @var{location}
3783Set a breakpoint at the given @var{location}, which can specify a
3784function name, a line number, or an address of an instruction.
3785(@xref{Specify Location}, for a list of all the possible ways to
3786specify a @var{location}.) The breakpoint will stop your program just
3787before it executes any of the code in the specified @var{location}.
3788
c906108c 3789When using source languages that permit overloading of symbols, such as
2a25a5ba 3790C@t{++}, a function name may refer to more than one possible place to break.
6ba66d6a
JB
3791@xref{Ambiguous Expressions,,Ambiguous Expressions}, for a discussion of
3792that situation.
c906108c 3793
45ac276d 3794It is also possible to insert a breakpoint that will stop the program
2c88c651
JB
3795only if a specific thread (@pxref{Thread-Specific Breakpoints})
3796or a specific task (@pxref{Ada Tasks}) hits that breakpoint.
45ac276d 3797
c906108c
SS
3798@item break
3799When called without any arguments, @code{break} sets a breakpoint at
3800the next instruction to be executed in the selected stack frame
3801(@pxref{Stack, ,Examining the Stack}). In any selected frame but the
3802innermost, this makes your program stop as soon as control
3803returns to that frame. This is similar to the effect of a
3804@code{finish} command in the frame inside the selected frame---except
3805that @code{finish} does not leave an active breakpoint. If you use
3806@code{break} without an argument in the innermost frame, @value{GDBN} stops
3807the next time it reaches the current location; this may be useful
3808inside loops.
3809
3810@value{GDBN} normally ignores breakpoints when it resumes execution, until at
3811least one instruction has been executed. If it did not do this, you
3812would be unable to proceed past a breakpoint without first disabling the
3813breakpoint. This rule applies whether or not the breakpoint already
3814existed when your program stopped.
3815
3816@item break @dots{} if @var{cond}
3817Set a breakpoint with condition @var{cond}; evaluate the expression
3818@var{cond} each time the breakpoint is reached, and stop only if the
3819value is nonzero---that is, if @var{cond} evaluates as true.
3820@samp{@dots{}} stands for one of the possible arguments described
3821above (or no argument) specifying where to break. @xref{Conditions,
79a6e687 3822,Break Conditions}, for more information on breakpoint conditions.
c906108c
SS
3823
3824@kindex tbreak
3825@item tbreak @var{args}
697aa1b7 3826Set a breakpoint enabled only for one stop. The @var{args} are the
c906108c
SS
3827same as for the @code{break} command, and the breakpoint is set in the same
3828way, but the breakpoint is automatically deleted after the first time your
79a6e687 3829program stops there. @xref{Disabling, ,Disabling Breakpoints}.
c906108c 3830
c906108c 3831@kindex hbreak
ba04e063 3832@cindex hardware breakpoints
c906108c 3833@item hbreak @var{args}
697aa1b7 3834Set a hardware-assisted breakpoint. The @var{args} are the same as for the
d4f3574e 3835@code{break} command and the breakpoint is set in the same way, but the
c906108c
SS
3836breakpoint requires hardware support and some target hardware may not
3837have this support. The main purpose of this is EPROM/ROM code
d4f3574e
SS
3838debugging, so you can set a breakpoint at an instruction without
3839changing the instruction. This can be used with the new trap-generation
09d4efe1 3840provided by SPARClite DSU and most x86-based targets. These targets
d4f3574e
SS
3841will generate traps when a program accesses some data or instruction
3842address that is assigned to the debug registers. However the hardware
3843breakpoint registers can take a limited number of breakpoints. For
3844example, on the DSU, only two data breakpoints can be set at a time, and
3845@value{GDBN} will reject this command if more than two are used. Delete
3846or disable unused hardware breakpoints before setting new ones
79a6e687
BW
3847(@pxref{Disabling, ,Disabling Breakpoints}).
3848@xref{Conditions, ,Break Conditions}.
9c16f35a
EZ
3849For remote targets, you can restrict the number of hardware
3850breakpoints @value{GDBN} will use, see @ref{set remote
3851hardware-breakpoint-limit}.
501eef12 3852
c906108c
SS
3853@kindex thbreak
3854@item thbreak @var{args}
697aa1b7 3855Set a hardware-assisted breakpoint enabled only for one stop. The @var{args}
c906108c 3856are the same as for the @code{hbreak} command and the breakpoint is set in
5d161b24 3857the same way. However, like the @code{tbreak} command,
c906108c
SS
3858the breakpoint is automatically deleted after the
3859first time your program stops there. Also, like the @code{hbreak}
5d161b24 3860command, the breakpoint requires hardware support and some target hardware
79a6e687
BW
3861may not have this support. @xref{Disabling, ,Disabling Breakpoints}.
3862See also @ref{Conditions, ,Break Conditions}.
c906108c
SS
3863
3864@kindex rbreak
3865@cindex regular expression
8bd10a10 3866@cindex breakpoints at functions matching a regexp
c45da7e6 3867@cindex set breakpoints in many functions
c906108c 3868@item rbreak @var{regex}
c906108c 3869Set breakpoints on all functions matching the regular expression
11cf8741
JM
3870@var{regex}. This command sets an unconditional breakpoint on all
3871matches, printing a list of all breakpoints it set. Once these
3872breakpoints are set, they are treated just like the breakpoints set with
3873the @code{break} command. You can delete them, disable them, or make
3874them conditional the same way as any other breakpoint.
3875
20813a0b
PW
3876In programs using different languages, @value{GDBN} chooses the syntax
3877to print the list of all breakpoints it sets according to the
3878@samp{set language} value: using @samp{set language auto}
3879(see @ref{Automatically, ,Set Language Automatically}) means to use the
3880language of the breakpoint's function, other values mean to use
3881the manually specified language (see @ref{Manually, ,Set Language Manually}).
3882
11cf8741
JM
3883The syntax of the regular expression is the standard one used with tools
3884like @file{grep}. Note that this is different from the syntax used by
3885shells, so for instance @code{foo*} matches all functions that include
3886an @code{fo} followed by zero or more @code{o}s. There is an implicit
3887@code{.*} leading and trailing the regular expression you supply, so to
3888match only functions that begin with @code{foo}, use @code{^foo}.
c906108c 3889
f7dc1244 3890@cindex non-member C@t{++} functions, set breakpoint in
b37052ae 3891When debugging C@t{++} programs, @code{rbreak} is useful for setting
c906108c
SS
3892breakpoints on overloaded functions that are not members of any special
3893classes.
c906108c 3894
f7dc1244
EZ
3895@cindex set breakpoints on all functions
3896The @code{rbreak} command can be used to set breakpoints in
3897@strong{all} the functions in a program, like this:
3898
3899@smallexample
3900(@value{GDBP}) rbreak .
3901@end smallexample
3902
8bd10a10
CM
3903@item rbreak @var{file}:@var{regex}
3904If @code{rbreak} is called with a filename qualification, it limits
3905the search for functions matching the given regular expression to the
3906specified @var{file}. This can be used, for example, to set breakpoints on
3907every function in a given file:
3908
3909@smallexample
3910(@value{GDBP}) rbreak file.c:.
3911@end smallexample
3912
3913The colon separating the filename qualifier from the regex may
3914optionally be surrounded by spaces.
3915
c906108c
SS
3916@kindex info breakpoints
3917@cindex @code{$_} and @code{info breakpoints}
18da0c51
MG
3918@item info breakpoints @r{[}@var{list}@dots{}@r{]}
3919@itemx info break @r{[}@var{list}@dots{}@r{]}
c906108c 3920Print a table of all breakpoints, watchpoints, and catchpoints set and
45ac1734 3921not deleted. Optional argument @var{n} means print information only
e5a67952
MS
3922about the specified breakpoint(s) (or watchpoint(s) or catchpoint(s)).
3923For each breakpoint, following columns are printed:
c906108c
SS
3924
3925@table @emph
3926@item Breakpoint Numbers
3927@item Type
3928Breakpoint, watchpoint, or catchpoint.
3929@item Disposition
3930Whether the breakpoint is marked to be disabled or deleted when hit.
3931@item Enabled or Disabled
3932Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints
b3db7447 3933that are not enabled.
c906108c 3934@item Address
fe6fbf8b 3935Where the breakpoint is in your program, as a memory address. For a
b3db7447
NR
3936pending breakpoint whose address is not yet known, this field will
3937contain @samp{<PENDING>}. Such breakpoint won't fire until a shared
3938library that has the symbol or line referred by breakpoint is loaded.
3939See below for details. A breakpoint with several locations will
3b784c4f 3940have @samp{<MULTIPLE>} in this field---see below for details.
c906108c
SS
3941@item What
3942Where the breakpoint is in the source for your program, as a file and
2650777c
JJ
3943line number. For a pending breakpoint, the original string passed to
3944the breakpoint command will be listed as it cannot be resolved until
3945the appropriate shared library is loaded in the future.
c906108c
SS
3946@end table
3947
3948@noindent
83364271
LM
3949If a breakpoint is conditional, there are two evaluation modes: ``host'' and
3950``target''. If mode is ``host'', breakpoint condition evaluation is done by
3951@value{GDBN} on the host's side. If it is ``target'', then the condition
3952is evaluated by the target. The @code{info break} command shows
3953the condition on the line following the affected breakpoint, together with
3954its condition evaluation mode in between parentheses.
3955
3956Breakpoint commands, if any, are listed after that. A pending breakpoint is
3957allowed to have a condition specified for it. The condition is not parsed for
3958validity until a shared library is loaded that allows the pending
3959breakpoint to resolve to a valid location.
c906108c
SS
3960
3961@noindent
3962@code{info break} with a breakpoint
3963number @var{n} as argument lists only that breakpoint. The
3964convenience variable @code{$_} and the default examining-address for
3965the @code{x} command are set to the address of the last breakpoint
79a6e687 3966listed (@pxref{Memory, ,Examining Memory}).
c906108c
SS
3967
3968@noindent
3969@code{info break} displays a count of the number of times the breakpoint
3970has been hit. This is especially useful in conjunction with the
3971@code{ignore} command. You can ignore a large number of breakpoint
3972hits, look at the breakpoint info to see how many times the breakpoint
3973was hit, and then run again, ignoring one less than that number. This
3974will get you quickly to the last hit of that breakpoint.
816338b5
SS
3975
3976@noindent
3977For a breakpoints with an enable count (xref) greater than 1,
3978@code{info break} also displays that count.
3979
c906108c
SS
3980@end table
3981
3982@value{GDBN} allows you to set any number of breakpoints at the same place in
3983your program. There is nothing silly or meaningless about this. When
3984the breakpoints are conditional, this is even useful
79a6e687 3985(@pxref{Conditions, ,Break Conditions}).
c906108c 3986
2e9132cc
EZ
3987@cindex multiple locations, breakpoints
3988@cindex breakpoints, multiple locations
fcda367b 3989It is possible that a breakpoint corresponds to several locations
fe6fbf8b
VP
3990in your program. Examples of this situation are:
3991
3992@itemize @bullet
f8eba3c6
TT
3993@item
3994Multiple functions in the program may have the same name.
3995
fe6fbf8b
VP
3996@item
3997For a C@t{++} constructor, the @value{NGCC} compiler generates several
3998instances of the function body, used in different cases.
3999
4000@item
4001For a C@t{++} template function, a given line in the function can
4002correspond to any number of instantiations.
4003
4004@item
4005For an inlined function, a given source line can correspond to
4006several places where that function is inlined.
fe6fbf8b
VP
4007@end itemize
4008
4009In all those cases, @value{GDBN} will insert a breakpoint at all
f8eba3c6 4010the relevant locations.
fe6fbf8b 4011
3b784c4f
EZ
4012A breakpoint with multiple locations is displayed in the breakpoint
4013table using several rows---one header row, followed by one row for
4014each breakpoint location. The header row has @samp{<MULTIPLE>} in the
4015address column. The rows for individual locations contain the actual
4016addresses for locations, and show the functions to which those
4017locations belong. The number column for a location is of the form
fe6fbf8b
VP
4018@var{breakpoint-number}.@var{location-number}.
4019
4020For example:
3b784c4f 4021
fe6fbf8b
VP
4022@smallexample
4023Num Type Disp Enb Address What
40241 breakpoint keep y <MULTIPLE>
4025 stop only if i==1
4026 breakpoint already hit 1 time
40271.1 y 0x080486a2 in void foo<int>() at t.cc:8
40281.2 y 0x080486ca in void foo<double>() at t.cc:8
4029@end smallexample
4030
d0fe4701
XR
4031You cannot delete the individual locations from a breakpoint. However,
4032each location can be individually enabled or disabled by passing
fe6fbf8b 4033@var{breakpoint-number}.@var{location-number} as argument to the
d0fe4701
XR
4034@code{enable} and @code{disable} commands. It's also possible to
4035@code{enable} and @code{disable} a range of @var{location-number}
4036locations using a @var{breakpoint-number} and two @var{location-number}s,
4037in increasing order, separated by a hyphen, like
4038@kbd{@var{breakpoint-number}.@var{location-number1}-@var{location-number2}},
4039in which case @value{GDBN} acts on all the locations in the range (inclusive).
4040Disabling or enabling the parent breakpoint (@pxref{Disabling}) affects
4041all of the locations that belong to that breakpoint.
fe6fbf8b 4042
2650777c 4043@cindex pending breakpoints
fe6fbf8b 4044It's quite common to have a breakpoint inside a shared library.
3b784c4f 4045Shared libraries can be loaded and unloaded explicitly,
fe6fbf8b
VP
4046and possibly repeatedly, as the program is executed. To support
4047this use case, @value{GDBN} updates breakpoint locations whenever
4048any shared library is loaded or unloaded. Typically, you would
fcda367b 4049set a breakpoint in a shared library at the beginning of your
fe6fbf8b
VP
4050debugging session, when the library is not loaded, and when the
4051symbols from the library are not available. When you try to set
4052breakpoint, @value{GDBN} will ask you if you want to set
3b784c4f 4053a so called @dfn{pending breakpoint}---breakpoint whose address
fe6fbf8b
VP
4054is not yet resolved.
4055
4056After the program is run, whenever a new shared library is loaded,
4057@value{GDBN} reevaluates all the breakpoints. When a newly loaded
4058shared library contains the symbol or line referred to by some
4059pending breakpoint, that breakpoint is resolved and becomes an
4060ordinary breakpoint. When a library is unloaded, all breakpoints
4061that refer to its symbols or source lines become pending again.
4062
4063This logic works for breakpoints with multiple locations, too. For
4064example, if you have a breakpoint in a C@t{++} template function, and
4065a newly loaded shared library has an instantiation of that template,
4066a new location is added to the list of locations for the breakpoint.
4067
4068Except for having unresolved address, pending breakpoints do not
4069differ from regular breakpoints. You can set conditions or commands,
4070enable and disable them and perform other breakpoint operations.
4071
4072@value{GDBN} provides some additional commands for controlling what
4073happens when the @samp{break} command cannot resolve breakpoint
4074address specification to an address:
dd79a6cf
JJ
4075
4076@kindex set breakpoint pending
4077@kindex show breakpoint pending
4078@table @code
4079@item set breakpoint pending auto
4080This is the default behavior. When @value{GDBN} cannot find the breakpoint
4081location, it queries you whether a pending breakpoint should be created.
4082
4083@item set breakpoint pending on
4084This indicates that an unrecognized breakpoint location should automatically
4085result in a pending breakpoint being created.
4086
4087@item set breakpoint pending off
4088This indicates that pending breakpoints are not to be created. Any
4089unrecognized breakpoint location results in an error. This setting does
4090not affect any pending breakpoints previously created.
4091
4092@item show breakpoint pending
4093Show the current behavior setting for creating pending breakpoints.
4094@end table
2650777c 4095
fe6fbf8b
VP
4096The settings above only affect the @code{break} command and its
4097variants. Once breakpoint is set, it will be automatically updated
4098as shared libraries are loaded and unloaded.
2650777c 4099
765dc015
VP
4100@cindex automatic hardware breakpoints
4101For some targets, @value{GDBN} can automatically decide if hardware or
4102software breakpoints should be used, depending on whether the
4103breakpoint address is read-only or read-write. This applies to
4104breakpoints set with the @code{break} command as well as to internal
4105breakpoints set by commands like @code{next} and @code{finish}. For
fcda367b 4106breakpoints set with @code{hbreak}, @value{GDBN} will always use hardware
765dc015
VP
4107breakpoints.
4108
18da0c51 4109You can control this automatic behaviour with the following commands:
765dc015
VP
4110
4111@kindex set breakpoint auto-hw
4112@kindex show breakpoint auto-hw
4113@table @code
4114@item set breakpoint auto-hw on
4115This is the default behavior. When @value{GDBN} sets a breakpoint, it
4116will try to use the target memory map to decide if software or hardware
4117breakpoint must be used.
4118
4119@item set breakpoint auto-hw off
4120This indicates @value{GDBN} should not automatically select breakpoint
4121type. If the target provides a memory map, @value{GDBN} will warn when
4122trying to set software breakpoint at a read-only address.
4123@end table
4124
74960c60
VP
4125@value{GDBN} normally implements breakpoints by replacing the program code
4126at the breakpoint address with a special instruction, which, when
4127executed, given control to the debugger. By default, the program
4128code is so modified only when the program is resumed. As soon as
4129the program stops, @value{GDBN} restores the original instructions. This
4130behaviour guards against leaving breakpoints inserted in the
4131target should gdb abrubptly disconnect. However, with slow remote
4132targets, inserting and removing breakpoint can reduce the performance.
4133This behavior can be controlled with the following commands::
4134
4135@kindex set breakpoint always-inserted
4136@kindex show breakpoint always-inserted
4137@table @code
4138@item set breakpoint always-inserted off
33e5cbd6
PA
4139All breakpoints, including newly added by the user, are inserted in
4140the target only when the target is resumed. All breakpoints are
a25a5a45 4141removed from the target when it stops. This is the default mode.
74960c60
VP
4142
4143@item set breakpoint always-inserted on
4144Causes all breakpoints to be inserted in the target at all times. If
4145the user adds a new breakpoint, or changes an existing breakpoint, the
4146breakpoints in the target are updated immediately. A breakpoint is
a25a5a45 4147removed from the target only when breakpoint itself is deleted.
342cc091 4148@end table
765dc015 4149
83364271
LM
4150@value{GDBN} handles conditional breakpoints by evaluating these conditions
4151when a breakpoint breaks. If the condition is true, then the process being
4152debugged stops, otherwise the process is resumed.
4153
4154If the target supports evaluating conditions on its end, @value{GDBN} may
4155download the breakpoint, together with its conditions, to it.
4156
4157This feature can be controlled via the following commands:
4158
4159@kindex set breakpoint condition-evaluation
4160@kindex show breakpoint condition-evaluation
4161@table @code
4162@item set breakpoint condition-evaluation host
4163This option commands @value{GDBN} to evaluate the breakpoint
4164conditions on the host's side. Unconditional breakpoints are sent to
4165the target which in turn receives the triggers and reports them back to GDB
4166for condition evaluation. This is the standard evaluation mode.
4167
4168@item set breakpoint condition-evaluation target
4169This option commands @value{GDBN} to download breakpoint conditions
4170to the target at the moment of their insertion. The target
4171is responsible for evaluating the conditional expression and reporting
4172breakpoint stop events back to @value{GDBN} whenever the condition
4173is true. Due to limitations of target-side evaluation, some conditions
4174cannot be evaluated there, e.g., conditions that depend on local data
4175that is only known to the host. Examples include
4176conditional expressions involving convenience variables, complex types
4177that cannot be handled by the agent expression parser and expressions
4178that are too long to be sent over to the target, specially when the
4179target is a remote system. In these cases, the conditions will be
4180evaluated by @value{GDBN}.
4181
4182@item set breakpoint condition-evaluation auto
4183This is the default mode. If the target supports evaluating breakpoint
4184conditions on its end, @value{GDBN} will download breakpoint conditions to
4185the target (limitations mentioned previously apply). If the target does
4186not support breakpoint condition evaluation, then @value{GDBN} will fallback
4187to evaluating all these conditions on the host's side.
4188@end table
4189
4190
c906108c
SS
4191@cindex negative breakpoint numbers
4192@cindex internal @value{GDBN} breakpoints
eb12ee30
AC
4193@value{GDBN} itself sometimes sets breakpoints in your program for
4194special purposes, such as proper handling of @code{longjmp} (in C
4195programs). These internal breakpoints are assigned negative numbers,
4196starting with @code{-1}; @samp{info breakpoints} does not display them.
c906108c 4197You can see these breakpoints with the @value{GDBN} maintenance command
eb12ee30 4198@samp{maint info breakpoints} (@pxref{maint info breakpoints}).
c906108c
SS
4199
4200
6d2ebf8b 4201@node Set Watchpoints
79a6e687 4202@subsection Setting Watchpoints
c906108c
SS
4203
4204@cindex setting watchpoints
c906108c
SS
4205You can use a watchpoint to stop execution whenever the value of an
4206expression changes, without having to predict a particular place where
fd60e0df
EZ
4207this may happen. (This is sometimes called a @dfn{data breakpoint}.)
4208The expression may be as simple as the value of a single variable, or
4209as complex as many variables combined by operators. Examples include:
4210
4211@itemize @bullet
4212@item
4213A reference to the value of a single variable.
4214
4215@item
4216An address cast to an appropriate data type. For example,
4217@samp{*(int *)0x12345678} will watch a 4-byte region at the specified
4218address (assuming an @code{int} occupies 4 bytes).
4219
4220@item
4221An arbitrarily complex expression, such as @samp{a*b + c/d}. The
4222expression can use any operators valid in the program's native
4223language (@pxref{Languages}).
4224@end itemize
c906108c 4225
fa4727a6
DJ
4226You can set a watchpoint on an expression even if the expression can
4227not be evaluated yet. For instance, you can set a watchpoint on
4228@samp{*global_ptr} before @samp{global_ptr} is initialized.
4229@value{GDBN} will stop when your program sets @samp{global_ptr} and
4230the expression produces a valid value. If the expression becomes
4231valid in some other way than changing a variable (e.g.@: if the memory
4232pointed to by @samp{*global_ptr} becomes readable as the result of a
4233@code{malloc} call), @value{GDBN} may not stop until the next time
4234the expression changes.
4235
82f2d802
EZ
4236@cindex software watchpoints
4237@cindex hardware watchpoints
c906108c 4238Depending on your system, watchpoints may be implemented in software or
2df3850c 4239hardware. @value{GDBN} does software watchpointing by single-stepping your
c906108c
SS
4240program and testing the variable's value each time, which is hundreds of
4241times slower than normal execution. (But this may still be worth it, to
4242catch errors where you have no clue what part of your program is the
4243culprit.)
4244
b1236ac3
PA
4245On some systems, such as most PowerPC or x86-based targets,
4246@value{GDBN} includes support for hardware watchpoints, which do not
4247slow down the running of your program.
c906108c
SS
4248
4249@table @code
4250@kindex watch
5d5658a1 4251@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
fd60e0df
EZ
4252Set a watchpoint for an expression. @value{GDBN} will break when the
4253expression @var{expr} is written into by the program and its value
4254changes. The simplest (and the most popular) use of this command is
4255to watch the value of a single variable:
4256
4257@smallexample
4258(@value{GDBP}) watch foo
4259@end smallexample
c906108c 4260
5d5658a1 4261If the command includes a @code{@r{[}thread @var{thread-id}@r{]}}
9c06b0b4 4262argument, @value{GDBN} breaks only when the thread identified by
5d5658a1 4263@var{thread-id} changes the value of @var{expr}. If any other threads
d8b2a693
JB
4264change the value of @var{expr}, @value{GDBN} will not break. Note
4265that watchpoints restricted to a single thread in this way only work
4266with Hardware Watchpoints.
4267
06a64a0b
TT
4268Ordinarily a watchpoint respects the scope of variables in @var{expr}
4269(see below). The @code{-location} argument tells @value{GDBN} to
4270instead watch the memory referred to by @var{expr}. In this case,
4271@value{GDBN} will evaluate @var{expr}, take the address of the result,
4272and watch the memory at that address. The type of the result is used
4273to determine the size of the watched memory. If the expression's
4274result does not have an address, then @value{GDBN} will print an
4275error.
4276
9c06b0b4
TJB
4277The @code{@r{[}mask @var{maskvalue}@r{]}} argument allows creation
4278of masked watchpoints, if the current architecture supports this
4279feature (e.g., PowerPC Embedded architecture, see @ref{PowerPC
4280Embedded}.) A @dfn{masked watchpoint} specifies a mask in addition
4281to an address to watch. The mask specifies that some bits of an address
4282(the bits which are reset in the mask) should be ignored when matching
4283the address accessed by the inferior against the watchpoint address.
4284Thus, a masked watchpoint watches many addresses simultaneously---those
4285addresses whose unmasked bits are identical to the unmasked bits in the
4286watchpoint address. The @code{mask} argument implies @code{-location}.
4287Examples:
4288
4289@smallexample
4290(@value{GDBP}) watch foo mask 0xffff00ff
4291(@value{GDBP}) watch *0xdeadbeef mask 0xffffff00
4292@end smallexample
4293
c906108c 4294@kindex rwatch
5d5658a1 4295@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
09d4efe1
EZ
4296Set a watchpoint that will break when the value of @var{expr} is read
4297by the program.
c906108c
SS
4298
4299@kindex awatch
5d5658a1 4300@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
09d4efe1
EZ
4301Set a watchpoint that will break when @var{expr} is either read from
4302or written into by the program.
c906108c 4303
18da0c51
MG
4304@kindex info watchpoints @r{[}@var{list}@dots{}@r{]}
4305@item info watchpoints @r{[}@var{list}@dots{}@r{]}
d77f58be
SS
4306This command prints a list of watchpoints, using the same format as
4307@code{info break} (@pxref{Set Breaks}).
c906108c
SS
4308@end table
4309
65d79d4b
SDJ
4310If you watch for a change in a numerically entered address you need to
4311dereference it, as the address itself is just a constant number which will
4312never change. @value{GDBN} refuses to create a watchpoint that watches
4313a never-changing value:
4314
4315@smallexample
4316(@value{GDBP}) watch 0x600850
4317Cannot watch constant value 0x600850.
4318(@value{GDBP}) watch *(int *) 0x600850
4319Watchpoint 1: *(int *) 6293584
4320@end smallexample
4321
c906108c
SS
4322@value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware
4323watchpoints execute very quickly, and the debugger reports a change in
4324value at the exact instruction where the change occurs. If @value{GDBN}
4325cannot set a hardware watchpoint, it sets a software watchpoint, which
4326executes more slowly and reports the change in value at the next
82f2d802
EZ
4327@emph{statement}, not the instruction, after the change occurs.
4328
82f2d802
EZ
4329@cindex use only software watchpoints
4330You can force @value{GDBN} to use only software watchpoints with the
4331@kbd{set can-use-hw-watchpoints 0} command. With this variable set to
4332zero, @value{GDBN} will never try to use hardware watchpoints, even if
4333the underlying system supports them. (Note that hardware-assisted
4334watchpoints that were set @emph{before} setting
4335@code{can-use-hw-watchpoints} to zero will still use the hardware
d3e8051b 4336mechanism of watching expression values.)
c906108c 4337
9c16f35a
EZ
4338@table @code
4339@item set can-use-hw-watchpoints
4340@kindex set can-use-hw-watchpoints
4341Set whether or not to use hardware watchpoints.
4342
4343@item show can-use-hw-watchpoints
4344@kindex show can-use-hw-watchpoints
4345Show the current mode of using hardware watchpoints.
4346@end table
4347
4348For remote targets, you can restrict the number of hardware
4349watchpoints @value{GDBN} will use, see @ref{set remote
4350hardware-breakpoint-limit}.
4351
c906108c
SS
4352When you issue the @code{watch} command, @value{GDBN} reports
4353
474c8240 4354@smallexample
c906108c 4355Hardware watchpoint @var{num}: @var{expr}
474c8240 4356@end smallexample
c906108c
SS
4357
4358@noindent
4359if it was able to set a hardware watchpoint.
4360
7be570e7
JM
4361Currently, the @code{awatch} and @code{rwatch} commands can only set
4362hardware watchpoints, because accesses to data that don't change the
4363value of the watched expression cannot be detected without examining
4364every instruction as it is being executed, and @value{GDBN} does not do
4365that currently. If @value{GDBN} finds that it is unable to set a
4366hardware breakpoint with the @code{awatch} or @code{rwatch} command, it
4367will print a message like this:
4368
4369@smallexample
4370Expression cannot be implemented with read/access watchpoint.
4371@end smallexample
4372
4373Sometimes, @value{GDBN} cannot set a hardware watchpoint because the
4374data type of the watched expression is wider than what a hardware
4375watchpoint on the target machine can handle. For example, some systems
4376can only watch regions that are up to 4 bytes wide; on such systems you
4377cannot set hardware watchpoints for an expression that yields a
4378double-precision floating-point number (which is typically 8 bytes
4379wide). As a work-around, it might be possible to break the large region
4380into a series of smaller ones and watch them with separate watchpoints.
4381
4382If you set too many hardware watchpoints, @value{GDBN} might be unable
4383to insert all of them when you resume the execution of your program.
4384Since the precise number of active watchpoints is unknown until such
4385time as the program is about to be resumed, @value{GDBN} might not be
4386able to warn you about this when you set the watchpoints, and the
4387warning will be printed only when the program is resumed:
4388
4389@smallexample
4390Hardware watchpoint @var{num}: Could not insert watchpoint
4391@end smallexample
4392
4393@noindent
4394If this happens, delete or disable some of the watchpoints.
4395
fd60e0df
EZ
4396Watching complex expressions that reference many variables can also
4397exhaust the resources available for hardware-assisted watchpoints.
4398That's because @value{GDBN} needs to watch every variable in the
4399expression with separately allocated resources.
4400
c906108c 4401If you call a function interactively using @code{print} or @code{call},
2df3850c 4402any watchpoints you have set will be inactive until @value{GDBN} reaches another
c906108c
SS
4403kind of breakpoint or the call completes.
4404
7be570e7
JM
4405@value{GDBN} automatically deletes watchpoints that watch local
4406(automatic) variables, or expressions that involve such variables, when
4407they go out of scope, that is, when the execution leaves the block in
4408which these variables were defined. In particular, when the program
4409being debugged terminates, @emph{all} local variables go out of scope,
4410and so only watchpoints that watch global variables remain set. If you
4411rerun the program, you will need to set all such watchpoints again. One
4412way of doing that would be to set a code breakpoint at the entry to the
4413@code{main} function and when it breaks, set all the watchpoints.
4414
c906108c
SS
4415@cindex watchpoints and threads
4416@cindex threads and watchpoints
d983da9c
DJ
4417In multi-threaded programs, watchpoints will detect changes to the
4418watched expression from every thread.
4419
4420@quotation
4421@emph{Warning:} In multi-threaded programs, software watchpoints
53a5351d
JM
4422have only limited usefulness. If @value{GDBN} creates a software
4423watchpoint, it can only watch the value of an expression @emph{in a
4424single thread}. If you are confident that the expression can only
4425change due to the current thread's activity (and if you are also
4426confident that no other thread can become current), then you can use
4427software watchpoints as usual. However, @value{GDBN} may not notice
4428when a non-current thread's activity changes the expression. (Hardware
4429watchpoints, in contrast, watch an expression in all threads.)
c906108c 4430@end quotation
c906108c 4431
501eef12
AC
4432@xref{set remote hardware-watchpoint-limit}.
4433
6d2ebf8b 4434@node Set Catchpoints
79a6e687 4435@subsection Setting Catchpoints
d4f3574e 4436@cindex catchpoints, setting
c906108c
SS
4437@cindex exception handlers
4438@cindex event handling
4439
4440You can use @dfn{catchpoints} to cause the debugger to stop for certain
b37052ae 4441kinds of program events, such as C@t{++} exceptions or the loading of a
c906108c
SS
4442shared library. Use the @code{catch} command to set a catchpoint.
4443
4444@table @code
4445@kindex catch
4446@item catch @var{event}
697aa1b7 4447Stop when @var{event} occurs. The @var{event} can be any of the following:
591f19e8 4448
c906108c 4449@table @code
cc16e6c9
TT
4450@item throw @r{[}@var{regexp}@r{]}
4451@itemx rethrow @r{[}@var{regexp}@r{]}
4452@itemx catch @r{[}@var{regexp}@r{]}
1a4f73eb
TT
4453@kindex catch throw
4454@kindex catch rethrow
4455@kindex catch catch
4644b6e3 4456@cindex stop on C@t{++} exceptions
591f19e8
TT
4457The throwing, re-throwing, or catching of a C@t{++} exception.
4458
cc16e6c9
TT
4459If @var{regexp} is given, then only exceptions whose type matches the
4460regular expression will be caught.
4461
72f1fe8a
TT
4462@vindex $_exception@r{, convenience variable}
4463The convenience variable @code{$_exception} is available at an
4464exception-related catchpoint, on some systems. This holds the
4465exception being thrown.
4466
591f19e8
TT
4467There are currently some limitations to C@t{++} exception handling in
4468@value{GDBN}:
c906108c 4469
591f19e8
TT
4470@itemize @bullet
4471@item
4472The support for these commands is system-dependent. Currently, only
4473systems using the @samp{gnu-v3} C@t{++} ABI (@pxref{ABI}) are
4474supported.
4475
72f1fe8a 4476@item
cc16e6c9
TT
4477The regular expression feature and the @code{$_exception} convenience
4478variable rely on the presence of some SDT probes in @code{libstdc++}.
4479If these probes are not present, then these features cannot be used.
dee368d3
TT
4480These probes were first available in the GCC 4.8 release, but whether
4481or not they are available in your GCC also depends on how it was
4482built.
72f1fe8a
TT
4483
4484@item
4485The @code{$_exception} convenience variable is only valid at the
4486instruction at which an exception-related catchpoint is set.
4487
591f19e8
TT
4488@item
4489When an exception-related catchpoint is hit, @value{GDBN} stops at a
4490location in the system library which implements runtime exception
4491support for C@t{++}, usually @code{libstdc++}. You can use @code{up}
4492(@pxref{Selection}) to get to your code.
4493
4494@item
4495If you call a function interactively, @value{GDBN} normally returns
4496control to you when the function has finished executing. If the call
4497raises an exception, however, the call may bypass the mechanism that
4498returns control to you and cause your program either to abort or to
4499simply continue running until it hits a breakpoint, catches a signal
4500that @value{GDBN} is listening for, or exits. This is the case even if
4501you set a catchpoint for the exception; catchpoints on exceptions are
4502disabled within interactive calls. @xref{Calling}, for information on
4503controlling this with @code{set unwind-on-terminating-exception}.
4504
4505@item
4506You cannot raise an exception interactively.
4507
4508@item
4509You cannot install an exception handler interactively.
4510@end itemize
c906108c 4511
8936fcda 4512@item exception
1a4f73eb 4513@kindex catch exception
8936fcda
JB
4514@cindex Ada exception catching
4515@cindex catch Ada exceptions
4516An Ada exception being raised. If an exception name is specified
4517at the end of the command (eg @code{catch exception Program_Error}),
4518the debugger will stop only when this specific exception is raised.
4519Otherwise, the debugger stops execution when any Ada exception is raised.
4520
87f67dba
JB
4521When inserting an exception catchpoint on a user-defined exception whose
4522name is identical to one of the exceptions defined by the language, the
4523fully qualified name must be used as the exception name. Otherwise,
4524@value{GDBN} will assume that it should stop on the pre-defined exception
4525rather than the user-defined one. For instance, assuming an exception
4526called @code{Constraint_Error} is defined in package @code{Pck}, then
4527the command to use to catch such exceptions is @kbd{catch exception
4528Pck.Constraint_Error}.
4529
9f757bf7
XR
4530@item handlers
4531@kindex catch handlers
4532@cindex Ada exception handlers catching
4533@cindex catch Ada exceptions when handled
4534An Ada exception being handled. If an exception name is
4535specified at the end of the command
4536 (eg @kbd{catch handlers Program_Error}), the debugger will stop
4537only when this specific exception is handled.
4538Otherwise, the debugger stops execution when any Ada exception is handled.
4539
4540When inserting a handlers catchpoint on a user-defined
4541exception whose name is identical to one of the exceptions
4542defined by the language, the fully qualified name must be used
4543as the exception name. Otherwise, @value{GDBN} will assume that it
4544should stop on the pre-defined exception rather than the
4545user-defined one. For instance, assuming an exception called
4546 @code{Constraint_Error} is defined in package @code{Pck}, then the
4547command to use to catch such exceptions handling is
4548@kbd{catch handlers Pck.Constraint_Error}.
4549
8936fcda 4550@item exception unhandled
1a4f73eb 4551@kindex catch exception unhandled
8936fcda
JB
4552An exception that was raised but is not handled by the program.
4553
4554@item assert
1a4f73eb 4555@kindex catch assert
8936fcda
JB
4556A failed Ada assertion.
4557
c906108c 4558@item exec
1a4f73eb 4559@kindex catch exec
4644b6e3 4560@cindex break on fork/exec
b1236ac3 4561A call to @code{exec}.
c906108c 4562
e9076973 4563@anchor{catch syscall}
a96d9b2e 4564@item syscall
e3487908 4565@itemx syscall @r{[}@var{name} @r{|} @var{number} @r{|} @r{group:}@var{groupname} @r{|} @r{g:}@var{groupname}@r{]} @dots{}
1a4f73eb 4566@kindex catch syscall
a96d9b2e
SDJ
4567@cindex break on a system call.
4568A call to or return from a system call, a.k.a.@: @dfn{syscall}. A
4569syscall is a mechanism for application programs to request a service
4570from the operating system (OS) or one of the OS system services.
4571@value{GDBN} can catch some or all of the syscalls issued by the
4572debuggee, and show the related information for each syscall. If no
4573argument is specified, calls to and returns from all system calls
4574will be caught.
4575
4576@var{name} can be any system call name that is valid for the
4577underlying OS. Just what syscalls are valid depends on the OS. On
4578GNU and Unix systems, you can find the full list of valid syscall
4579names on @file{/usr/include/asm/unistd.h}.
4580
4581@c For MS-Windows, the syscall names and the corresponding numbers
4582@c can be found, e.g., on this URL:
4583@c http://www.metasploit.com/users/opcode/syscalls.html
4584@c but we don't support Windows syscalls yet.
4585
4586Normally, @value{GDBN} knows in advance which syscalls are valid for
4587each OS, so you can use the @value{GDBN} command-line completion
4588facilities (@pxref{Completion,, command completion}) to list the
4589available choices.
4590
4591You may also specify the system call numerically. A syscall's
4592number is the value passed to the OS's syscall dispatcher to
4593identify the requested service. When you specify the syscall by its
4594name, @value{GDBN} uses its database of syscalls to convert the name
4595into the corresponding numeric code, but using the number directly
4596may be useful if @value{GDBN}'s database does not have the complete
4597list of syscalls on your system (e.g., because @value{GDBN} lags
4598behind the OS upgrades).
4599
e3487908
GKB
4600You may specify a group of related syscalls to be caught at once using
4601the @code{group:} syntax (@code{g:} is a shorter equivalent). For
4602instance, on some platforms @value{GDBN} allows you to catch all
4603network related syscalls, by passing the argument @code{group:network}
4604to @code{catch syscall}. Note that not all syscall groups are
4605available in every system. You can use the command completion
4606facilities (@pxref{Completion,, command completion}) to list the
4607syscall groups available on your environment.
4608
a96d9b2e
SDJ
4609The example below illustrates how this command works if you don't provide
4610arguments to it:
4611
4612@smallexample
4613(@value{GDBP}) catch syscall
4614Catchpoint 1 (syscall)
4615(@value{GDBP}) r
4616Starting program: /tmp/catch-syscall
4617
4618Catchpoint 1 (call to syscall 'close'), \
4619 0xffffe424 in __kernel_vsyscall ()
4620(@value{GDBP}) c
4621Continuing.
4622
4623Catchpoint 1 (returned from syscall 'close'), \
4624 0xffffe424 in __kernel_vsyscall ()
4625(@value{GDBP})
4626@end smallexample
4627
4628Here is an example of catching a system call by name:
4629
4630@smallexample
4631(@value{GDBP}) catch syscall chroot
4632Catchpoint 1 (syscall 'chroot' [61])
4633(@value{GDBP}) r
4634Starting program: /tmp/catch-syscall
4635
4636Catchpoint 1 (call to syscall 'chroot'), \
4637 0xffffe424 in __kernel_vsyscall ()
4638(@value{GDBP}) c
4639Continuing.
4640
4641Catchpoint 1 (returned from syscall 'chroot'), \
4642 0xffffe424 in __kernel_vsyscall ()
4643(@value{GDBP})
4644@end smallexample
4645
4646An example of specifying a system call numerically. In the case
4647below, the syscall number has a corresponding entry in the XML
4648file, so @value{GDBN} finds its name and prints it:
4649
4650@smallexample
4651(@value{GDBP}) catch syscall 252
4652Catchpoint 1 (syscall(s) 'exit_group')
4653(@value{GDBP}) r
4654Starting program: /tmp/catch-syscall
4655
4656Catchpoint 1 (call to syscall 'exit_group'), \
4657 0xffffe424 in __kernel_vsyscall ()
4658(@value{GDBP}) c
4659Continuing.
4660
4661Program exited normally.
4662(@value{GDBP})
4663@end smallexample
4664
e3487908
GKB
4665Here is an example of catching a syscall group:
4666
4667@smallexample
4668(@value{GDBP}) catch syscall group:process
4669Catchpoint 1 (syscalls 'exit' [1] 'fork' [2] 'waitpid' [7]
4670'execve' [11] 'wait4' [114] 'clone' [120] 'vfork' [190]
4671'exit_group' [252] 'waitid' [284] 'unshare' [310])
4672(@value{GDBP}) r
4673Starting program: /tmp/catch-syscall
4674
4675Catchpoint 1 (call to syscall fork), 0x00007ffff7df4e27 in open64 ()
4676 from /lib64/ld-linux-x86-64.so.2
4677
4678(@value{GDBP}) c
4679Continuing.
4680@end smallexample
4681
a96d9b2e
SDJ
4682However, there can be situations when there is no corresponding name
4683in XML file for that syscall number. In this case, @value{GDBN} prints
4684a warning message saying that it was not able to find the syscall name,
4685but the catchpoint will be set anyway. See the example below:
4686
4687@smallexample
4688(@value{GDBP}) catch syscall 764
4689warning: The number '764' does not represent a known syscall.
4690Catchpoint 2 (syscall 764)
4691(@value{GDBP})
4692@end smallexample
4693
4694If you configure @value{GDBN} using the @samp{--without-expat} option,
4695it will not be able to display syscall names. Also, if your
4696architecture does not have an XML file describing its system calls,
4697you will not be able to see the syscall names. It is important to
4698notice that these two features are used for accessing the syscall
4699name database. In either case, you will see a warning like this:
4700
4701@smallexample
4702(@value{GDBP}) catch syscall
4703warning: Could not open "syscalls/i386-linux.xml"
4704warning: Could not load the syscall XML file 'syscalls/i386-linux.xml'.
4705GDB will not be able to display syscall names.
4706Catchpoint 1 (syscall)
4707(@value{GDBP})
4708@end smallexample
4709
4710Of course, the file name will change depending on your architecture and system.
4711
4712Still using the example above, you can also try to catch a syscall by its
4713number. In this case, you would see something like:
4714
4715@smallexample
4716(@value{GDBP}) catch syscall 252
4717Catchpoint 1 (syscall(s) 252)
4718@end smallexample
4719
4720Again, in this case @value{GDBN} would not be able to display syscall's names.
4721
c906108c 4722@item fork
1a4f73eb 4723@kindex catch fork
b1236ac3 4724A call to @code{fork}.
c906108c
SS
4725
4726@item vfork
1a4f73eb 4727@kindex catch vfork
b1236ac3 4728A call to @code{vfork}.
c906108c 4729
edcc5120
TT
4730@item load @r{[}regexp@r{]}
4731@itemx unload @r{[}regexp@r{]}
1a4f73eb
TT
4732@kindex catch load
4733@kindex catch unload
edcc5120
TT
4734The loading or unloading of a shared library. If @var{regexp} is
4735given, then the catchpoint will stop only if the regular expression
4736matches one of the affected libraries.
4737
ab04a2af 4738@item signal @r{[}@var{signal}@dots{} @r{|} @samp{all}@r{]}
1a4f73eb 4739@kindex catch signal
ab04a2af
TT
4740The delivery of a signal.
4741
4742With no arguments, this catchpoint will catch any signal that is not
4743used internally by @value{GDBN}, specifically, all signals except
4744@samp{SIGTRAP} and @samp{SIGINT}.
4745
4746With the argument @samp{all}, all signals, including those used by
4747@value{GDBN}, will be caught. This argument cannot be used with other
4748signal names.
4749
4750Otherwise, the arguments are a list of signal names as given to
4751@code{handle} (@pxref{Signals}). Only signals specified in this list
4752will be caught.
4753
4754One reason that @code{catch signal} can be more useful than
4755@code{handle} is that you can attach commands and conditions to the
4756catchpoint.
4757
4758When a signal is caught by a catchpoint, the signal's @code{stop} and
4759@code{print} settings, as specified by @code{handle}, are ignored.
4760However, whether the signal is still delivered to the inferior depends
4761on the @code{pass} setting; this can be changed in the catchpoint's
4762commands.
4763
c906108c
SS
4764@end table
4765
4766@item tcatch @var{event}
1a4f73eb 4767@kindex tcatch
c906108c
SS
4768Set a catchpoint that is enabled only for one stop. The catchpoint is
4769automatically deleted after the first time the event is caught.
4770
4771@end table
4772
4773Use the @code{info break} command to list the current catchpoints.
4774
c906108c 4775
6d2ebf8b 4776@node Delete Breaks
79a6e687 4777@subsection Deleting Breakpoints
c906108c
SS
4778
4779@cindex clearing breakpoints, watchpoints, catchpoints
4780@cindex deleting breakpoints, watchpoints, catchpoints
4781It is often necessary to eliminate a breakpoint, watchpoint, or
4782catchpoint once it has done its job and you no longer want your program
4783to stop there. This is called @dfn{deleting} the breakpoint. A
4784breakpoint that has been deleted no longer exists; it is forgotten.
4785
4786With the @code{clear} command you can delete breakpoints according to
4787where they are in your program. With the @code{delete} command you can
4788delete individual breakpoints, watchpoints, or catchpoints by specifying
4789their breakpoint numbers.
4790
4791It is not necessary to delete a breakpoint to proceed past it. @value{GDBN}
4792automatically ignores breakpoints on the first instruction to be executed
4793when you continue execution without changing the execution address.
4794
4795@table @code
4796@kindex clear
4797@item clear
4798Delete any breakpoints at the next instruction to be executed in the
79a6e687 4799selected stack frame (@pxref{Selection, ,Selecting a Frame}). When
c906108c
SS
4800the innermost frame is selected, this is a good way to delete a
4801breakpoint where your program just stopped.
4802
2a25a5ba
EZ
4803@item clear @var{location}
4804Delete any breakpoints set at the specified @var{location}.
4805@xref{Specify Location}, for the various forms of @var{location}; the
4806most useful ones are listed below:
4807
4808@table @code
c906108c
SS
4809@item clear @var{function}
4810@itemx clear @var{filename}:@var{function}
09d4efe1 4811Delete any breakpoints set at entry to the named @var{function}.
c906108c
SS
4812
4813@item clear @var{linenum}
4814@itemx clear @var{filename}:@var{linenum}
09d4efe1
EZ
4815Delete any breakpoints set at or within the code of the specified
4816@var{linenum} of the specified @var{filename}.
2a25a5ba 4817@end table
c906108c
SS
4818
4819@cindex delete breakpoints
4820@kindex delete
41afff9a 4821@kindex d @r{(@code{delete})}
18da0c51 4822@item delete @r{[}breakpoints@r{]} @r{[}@var{list}@dots{}@r{]}
c5394b80 4823Delete the breakpoints, watchpoints, or catchpoints of the breakpoint
18da0c51 4824list specified as argument. If no argument is specified, delete all
c906108c
SS
4825breakpoints (@value{GDBN} asks confirmation, unless you have @code{set
4826confirm off}). You can abbreviate this command as @code{d}.
4827@end table
4828
6d2ebf8b 4829@node Disabling
79a6e687 4830@subsection Disabling Breakpoints
c906108c 4831
4644b6e3 4832@cindex enable/disable a breakpoint
c906108c
SS
4833Rather than deleting a breakpoint, watchpoint, or catchpoint, you might
4834prefer to @dfn{disable} it. This makes the breakpoint inoperative as if
4835it had been deleted, but remembers the information on the breakpoint so
4836that you can @dfn{enable} it again later.
4837
4838You disable and enable breakpoints, watchpoints, and catchpoints with
d77f58be
SS
4839the @code{enable} and @code{disable} commands, optionally specifying
4840one or more breakpoint numbers as arguments. Use @code{info break} to
4841print a list of all breakpoints, watchpoints, and catchpoints if you
4842do not know which numbers to use.
c906108c 4843
3b784c4f
EZ
4844Disabling and enabling a breakpoint that has multiple locations
4845affects all of its locations.
4846
816338b5
SS
4847A breakpoint, watchpoint, or catchpoint can have any of several
4848different states of enablement:
c906108c
SS
4849
4850@itemize @bullet
4851@item
4852Enabled. The breakpoint stops your program. A breakpoint set
4853with the @code{break} command starts out in this state.
4854@item
4855Disabled. The breakpoint has no effect on your program.
4856@item
4857Enabled once. The breakpoint stops your program, but then becomes
d4f3574e 4858disabled.
c906108c 4859@item
816338b5
SS
4860Enabled for a count. The breakpoint stops your program for the next
4861N times, then becomes disabled.
4862@item
c906108c 4863Enabled for deletion. The breakpoint stops your program, but
d4f3574e
SS
4864immediately after it does so it is deleted permanently. A breakpoint
4865set with the @code{tbreak} command starts out in this state.
c906108c
SS
4866@end itemize
4867
4868You can use the following commands to enable or disable breakpoints,
4869watchpoints, and catchpoints:
4870
4871@table @code
c906108c 4872@kindex disable
41afff9a 4873@kindex dis @r{(@code{disable})}
18da0c51 4874@item disable @r{[}breakpoints@r{]} @r{[}@var{list}@dots{}@r{]}
c906108c
SS
4875Disable the specified breakpoints---or all breakpoints, if none are
4876listed. A disabled breakpoint has no effect but is not forgotten. All
4877options such as ignore-counts, conditions and commands are remembered in
4878case the breakpoint is enabled again later. You may abbreviate
4879@code{disable} as @code{dis}.
4880
c906108c 4881@kindex enable
18da0c51 4882@item enable @r{[}breakpoints@r{]} @r{[}@var{list}@dots{}@r{]}
c906108c
SS
4883Enable the specified breakpoints (or all defined breakpoints). They
4884become effective once again in stopping your program.
4885
18da0c51 4886@item enable @r{[}breakpoints@r{]} once @var{list}@dots{}
c906108c
SS
4887Enable the specified breakpoints temporarily. @value{GDBN} disables any
4888of these breakpoints immediately after stopping your program.
4889
18da0c51 4890@item enable @r{[}breakpoints@r{]} count @var{count} @var{list}@dots{}
816338b5
SS
4891Enable the specified breakpoints temporarily. @value{GDBN} records
4892@var{count} with each of the specified breakpoints, and decrements a
4893breakpoint's count when it is hit. When any count reaches 0,
4894@value{GDBN} disables that breakpoint. If a breakpoint has an ignore
4895count (@pxref{Conditions, ,Break Conditions}), that will be
4896decremented to 0 before @var{count} is affected.
4897
18da0c51 4898@item enable @r{[}breakpoints@r{]} delete @var{list}@dots{}
c906108c
SS
4899Enable the specified breakpoints to work once, then die. @value{GDBN}
4900deletes any of these breakpoints as soon as your program stops there.
09d4efe1 4901Breakpoints set by the @code{tbreak} command start out in this state.
c906108c
SS
4902@end table
4903
d4f3574e
SS
4904@c FIXME: I think the following ``Except for [...] @code{tbreak}'' is
4905@c confusing: tbreak is also initially enabled.
c906108c 4906Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks,
79a6e687 4907,Setting Breakpoints}), breakpoints that you set are initially enabled;
c906108c
SS
4908subsequently, they become disabled or enabled only when you use one of
4909the commands above. (The command @code{until} can set and delete a
4910breakpoint of its own, but it does not change the state of your other
4911breakpoints; see @ref{Continuing and Stepping, ,Continuing and
79a6e687 4912Stepping}.)
c906108c 4913
6d2ebf8b 4914@node Conditions
79a6e687 4915@subsection Break Conditions
c906108c
SS
4916@cindex conditional breakpoints
4917@cindex breakpoint conditions
4918
4919@c FIXME what is scope of break condition expr? Context where wanted?
5d161b24 4920@c in particular for a watchpoint?
c906108c
SS
4921The simplest sort of breakpoint breaks every time your program reaches a
4922specified place. You can also specify a @dfn{condition} for a
4923breakpoint. A condition is just a Boolean expression in your
4924programming language (@pxref{Expressions, ,Expressions}). A breakpoint with
4925a condition evaluates the expression each time your program reaches it,
4926and your program stops only if the condition is @emph{true}.
4927
4928This is the converse of using assertions for program validation; in that
4929situation, you want to stop when the assertion is violated---that is,
4930when the condition is false. In C, if you want to test an assertion expressed
4931by the condition @var{assert}, you should set the condition
4932@samp{! @var{assert}} on the appropriate breakpoint.
4933
4934Conditions are also accepted for watchpoints; you may not need them,
4935since a watchpoint is inspecting the value of an expression anyhow---but
4936it might be simpler, say, to just set a watchpoint on a variable name,
4937and specify a condition that tests whether the new value is an interesting
4938one.
4939
4940Break conditions can have side effects, and may even call functions in
4941your program. This can be useful, for example, to activate functions
4942that log program progress, or to use your own print functions to
99e008fe 4943format special data structures. The effects are completely predictable
c906108c
SS
4944unless there is another enabled breakpoint at the same address. (In
4945that case, @value{GDBN} might see the other breakpoint first and stop your
4946program without checking the condition of this one.) Note that
d4f3574e
SS
4947breakpoint commands are usually more convenient and flexible than break
4948conditions for the
c906108c 4949purpose of performing side effects when a breakpoint is reached
79a6e687 4950(@pxref{Break Commands, ,Breakpoint Command Lists}).
c906108c 4951
83364271
LM
4952Breakpoint conditions can also be evaluated on the target's side if
4953the target supports it. Instead of evaluating the conditions locally,
4954@value{GDBN} encodes the expression into an agent expression
4955(@pxref{Agent Expressions}) suitable for execution on the target,
4956independently of @value{GDBN}. Global variables become raw memory
4957locations, locals become stack accesses, and so forth.
4958
4959In this case, @value{GDBN} will only be notified of a breakpoint trigger
4960when its condition evaluates to true. This mechanism may provide faster
4961response times depending on the performance characteristics of the target
4962since it does not need to keep @value{GDBN} informed about
4963every breakpoint trigger, even those with false conditions.
4964
c906108c
SS
4965Break conditions can be specified when a breakpoint is set, by using
4966@samp{if} in the arguments to the @code{break} command. @xref{Set
79a6e687 4967Breaks, ,Setting Breakpoints}. They can also be changed at any time
c906108c 4968with the @code{condition} command.
53a5351d 4969
c906108c
SS
4970You can also use the @code{if} keyword with the @code{watch} command.
4971The @code{catch} command does not recognize the @code{if} keyword;
4972@code{condition} is the only way to impose a further condition on a
4973catchpoint.
c906108c
SS
4974
4975@table @code
4976@kindex condition
4977@item condition @var{bnum} @var{expression}
4978Specify @var{expression} as the break condition for breakpoint,
4979watchpoint, or catchpoint number @var{bnum}. After you set a condition,
4980breakpoint @var{bnum} stops your program only if the value of
4981@var{expression} is true (nonzero, in C). When you use
4982@code{condition}, @value{GDBN} checks @var{expression} immediately for
4983syntactic correctness, and to determine whether symbols in it have
d4f3574e
SS
4984referents in the context of your breakpoint. If @var{expression} uses
4985symbols not referenced in the context of the breakpoint, @value{GDBN}
4986prints an error message:
4987
474c8240 4988@smallexample
d4f3574e 4989No symbol "foo" in current context.
474c8240 4990@end smallexample
d4f3574e
SS
4991
4992@noindent
c906108c
SS
4993@value{GDBN} does
4994not actually evaluate @var{expression} at the time the @code{condition}
d4f3574e
SS
4995command (or a command that sets a breakpoint with a condition, like
4996@code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}.
c906108c
SS
4997
4998@item condition @var{bnum}
4999Remove the condition from breakpoint number @var{bnum}. It becomes
5000an ordinary unconditional breakpoint.
5001@end table
5002
5003@cindex ignore count (of breakpoint)
5004A special case of a breakpoint condition is to stop only when the
5005breakpoint has been reached a certain number of times. This is so
5006useful that there is a special way to do it, using the @dfn{ignore
5007count} of the breakpoint. Every breakpoint has an ignore count, which
5008is an integer. Most of the time, the ignore count is zero, and
5009therefore has no effect. But if your program reaches a breakpoint whose
5010ignore count is positive, then instead of stopping, it just decrements
5011the ignore count by one and continues. As a result, if the ignore count
5012value is @var{n}, the breakpoint does not stop the next @var{n} times
5013your program reaches it.
5014
5015@table @code
5016@kindex ignore
5017@item ignore @var{bnum} @var{count}
5018Set the ignore count of breakpoint number @var{bnum} to @var{count}.
5019The next @var{count} times the breakpoint is reached, your program's
5020execution does not stop; other than to decrement the ignore count, @value{GDBN}
5021takes no action.
5022
5023To make the breakpoint stop the next time it is reached, specify
5024a count of zero.
5025
5026When you use @code{continue} to resume execution of your program from a
5027breakpoint, you can specify an ignore count directly as an argument to
5028@code{continue}, rather than using @code{ignore}. @xref{Continuing and
79a6e687 5029Stepping,,Continuing and Stepping}.
c906108c
SS
5030
5031If a breakpoint has a positive ignore count and a condition, the
5032condition is not checked. Once the ignore count reaches zero,
5033@value{GDBN} resumes checking the condition.
5034
5035You could achieve the effect of the ignore count with a condition such
5036as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that
5037is decremented each time. @xref{Convenience Vars, ,Convenience
79a6e687 5038Variables}.
c906108c
SS
5039@end table
5040
5041Ignore counts apply to breakpoints, watchpoints, and catchpoints.
5042
5043
6d2ebf8b 5044@node Break Commands
79a6e687 5045@subsection Breakpoint Command Lists
c906108c
SS
5046
5047@cindex breakpoint commands
5048You can give any breakpoint (or watchpoint or catchpoint) a series of
5049commands to execute when your program stops due to that breakpoint. For
5050example, you might want to print the values of certain expressions, or
5051enable other breakpoints.
5052
5053@table @code
5054@kindex commands
ca91424e 5055@kindex end@r{ (breakpoint commands)}
18da0c51 5056@item commands @r{[}@var{list}@dots{}@r{]}
c906108c
SS
5057@itemx @dots{} @var{command-list} @dots{}
5058@itemx end
95a42b64 5059Specify a list of commands for the given breakpoints. The commands
c906108c
SS
5060themselves appear on the following lines. Type a line containing just
5061@code{end} to terminate the commands.
5062
5063To remove all commands from a breakpoint, type @code{commands} and
5064follow it immediately with @code{end}; that is, give no commands.
5065
95a42b64
TT
5066With no argument, @code{commands} refers to the last breakpoint,
5067watchpoint, or catchpoint set (not to the breakpoint most recently
5068encountered). If the most recent breakpoints were set with a single
5069command, then the @code{commands} will apply to all the breakpoints
5070set by that command. This applies to breakpoints set by
86b17b60
PA
5071@code{rbreak}, and also applies when a single @code{break} command
5072creates multiple breakpoints (@pxref{Ambiguous Expressions,,Ambiguous
5073Expressions}).
c906108c
SS
5074@end table
5075
5076Pressing @key{RET} as a means of repeating the last @value{GDBN} command is
5077disabled within a @var{command-list}.
5078
5079You can use breakpoint commands to start your program up again. Simply
5080use the @code{continue} command, or @code{step}, or any other command
5081that resumes execution.
5082
5083Any other commands in the command list, after a command that resumes
5084execution, are ignored. This is because any time you resume execution
5085(even with a simple @code{next} or @code{step}), you may encounter
5086another breakpoint---which could have its own command list, leading to
5087ambiguities about which list to execute.
5088
5089@kindex silent
5090If the first command you specify in a command list is @code{silent}, the
5091usual message about stopping at a breakpoint is not printed. This may
5092be desirable for breakpoints that are to print a specific message and
5093then continue. If none of the remaining commands print anything, you
5094see no sign that the breakpoint was reached. @code{silent} is
5095meaningful only at the beginning of a breakpoint command list.
5096
5097The commands @code{echo}, @code{output}, and @code{printf} allow you to
5098print precisely controlled output, and are often useful in silent
79a6e687 5099breakpoints. @xref{Output, ,Commands for Controlled Output}.
c906108c
SS
5100
5101For example, here is how you could use breakpoint commands to print the
5102value of @code{x} at entry to @code{foo} whenever @code{x} is positive.
5103
474c8240 5104@smallexample
c906108c
SS
5105break foo if x>0
5106commands
5107silent
5108printf "x is %d\n",x
5109cont
5110end
474c8240 5111@end smallexample
c906108c
SS
5112
5113One application for breakpoint commands is to compensate for one bug so
5114you can test for another. Put a breakpoint just after the erroneous line
5115of code, give it a condition to detect the case in which something
5116erroneous has been done, and give it commands to assign correct values
5117to any variables that need them. End with the @code{continue} command
5118so that your program does not stop, and start with the @code{silent}
5119command so that no output is produced. Here is an example:
5120
474c8240 5121@smallexample
c906108c
SS
5122break 403
5123commands
5124silent
5125set x = y + 4
5126cont
5127end
474c8240 5128@end smallexample
c906108c 5129
e7e0cddf
SS
5130@node Dynamic Printf
5131@subsection Dynamic Printf
5132
5133@cindex dynamic printf
5134@cindex dprintf
5135The dynamic printf command @code{dprintf} combines a breakpoint with
5136formatted printing of your program's data to give you the effect of
5137inserting @code{printf} calls into your program on-the-fly, without
5138having to recompile it.
5139
5140In its most basic form, the output goes to the GDB console. However,
5141you can set the variable @code{dprintf-style} for alternate handling.
5142For instance, you can ask to format the output by calling your
5143program's @code{printf} function. This has the advantage that the
5144characters go to the program's output device, so they can recorded in
5145redirects to files and so forth.
5146
d3ce09f5
SS
5147If you are doing remote debugging with a stub or agent, you can also
5148ask to have the printf handled by the remote agent. In addition to
5149ensuring that the output goes to the remote program's device along
5150with any other output the program might produce, you can also ask that
5151the dprintf remain active even after disconnecting from the remote
5152target. Using the stub/agent is also more efficient, as it can do
5153everything without needing to communicate with @value{GDBN}.
5154
e7e0cddf
SS
5155@table @code
5156@kindex dprintf
5157@item dprintf @var{location},@var{template},@var{expression}[,@var{expression}@dots{}]
5158Whenever execution reaches @var{location}, print the values of one or
5159more @var{expressions} under the control of the string @var{template}.
5160To print several values, separate them with commas.
5161
5162@item set dprintf-style @var{style}
5163Set the dprintf output to be handled in one of several different
5164styles enumerated below. A change of style affects all existing
5165dynamic printfs immediately. (If you need individual control over the
5166print commands, simply define normal breakpoints with
5167explicitly-supplied command lists.)
5168
18da0c51 5169@table @code
e7e0cddf
SS
5170@item gdb
5171@kindex dprintf-style gdb
5172Handle the output using the @value{GDBN} @code{printf} command.
5173
5174@item call
5175@kindex dprintf-style call
5176Handle the output by calling a function in your program (normally
5177@code{printf}).
5178
d3ce09f5
SS
5179@item agent
5180@kindex dprintf-style agent
5181Have the remote debugging agent (such as @code{gdbserver}) handle
5182the output itself. This style is only available for agents that
5183support running commands on the target.
18da0c51 5184@end table
d3ce09f5 5185
e7e0cddf
SS
5186@item set dprintf-function @var{function}
5187Set the function to call if the dprintf style is @code{call}. By
5188default its value is @code{printf}. You may set it to any expression.
5189that @value{GDBN} can evaluate to a function, as per the @code{call}
5190command.
5191
5192@item set dprintf-channel @var{channel}
5193Set a ``channel'' for dprintf. If set to a non-empty value,
5194@value{GDBN} will evaluate it as an expression and pass the result as
5195a first argument to the @code{dprintf-function}, in the manner of
5196@code{fprintf} and similar functions. Otherwise, the dprintf format
5197string will be the first argument, in the manner of @code{printf}.
5198
5199As an example, if you wanted @code{dprintf} output to go to a logfile
5200that is a standard I/O stream assigned to the variable @code{mylog},
5201you could do the following:
5202
5203@example
5204(gdb) set dprintf-style call
5205(gdb) set dprintf-function fprintf
5206(gdb) set dprintf-channel mylog
5207(gdb) dprintf 25,"at line 25, glob=%d\n",glob
5208Dprintf 1 at 0x123456: file main.c, line 25.
5209(gdb) info break
52101 dprintf keep y 0x00123456 in main at main.c:25
5211 call (void) fprintf (mylog,"at line 25, glob=%d\n",glob)
5212 continue
5213(gdb)
5214@end example
5215
5216Note that the @code{info break} displays the dynamic printf commands
5217as normal breakpoint commands; you can thus easily see the effect of
5218the variable settings.
5219
d3ce09f5
SS
5220@item set disconnected-dprintf on
5221@itemx set disconnected-dprintf off
5222@kindex set disconnected-dprintf
5223Choose whether @code{dprintf} commands should continue to run if
5224@value{GDBN} has disconnected from the target. This only applies
5225if the @code{dprintf-style} is @code{agent}.
5226
5227@item show disconnected-dprintf off
5228@kindex show disconnected-dprintf
5229Show the current choice for disconnected @code{dprintf}.
5230
e7e0cddf
SS
5231@end table
5232
5233@value{GDBN} does not check the validity of function and channel,
5234relying on you to supply values that are meaningful for the contexts
5235in which they are being used. For instance, the function and channel
5236may be the values of local variables, but if that is the case, then
5237all enabled dynamic prints must be at locations within the scope of
5238those locals. If evaluation fails, @value{GDBN} will report an error.
5239
6149aea9
PA
5240@node Save Breakpoints
5241@subsection How to save breakpoints to a file
5242
5243To save breakpoint definitions to a file use the @w{@code{save
5244breakpoints}} command.
5245
5246@table @code
5247@kindex save breakpoints
5248@cindex save breakpoints to a file for future sessions
5249@item save breakpoints [@var{filename}]
5250This command saves all current breakpoint definitions together with
5251their commands and ignore counts, into a file @file{@var{filename}}
5252suitable for use in a later debugging session. This includes all
5253types of breakpoints (breakpoints, watchpoints, catchpoints,
5254tracepoints). To read the saved breakpoint definitions, use the
5255@code{source} command (@pxref{Command Files}). Note that watchpoints
5256with expressions involving local variables may fail to be recreated
5257because it may not be possible to access the context where the
5258watchpoint is valid anymore. Because the saved breakpoint definitions
5259are simply a sequence of @value{GDBN} commands that recreate the
5260breakpoints, you can edit the file in your favorite editing program,
5261and remove the breakpoint definitions you're not interested in, or
5262that can no longer be recreated.
5263@end table
5264
62e5f89c
SDJ
5265@node Static Probe Points
5266@subsection Static Probe Points
5267
5268@cindex static probe point, SystemTap
3133f8c1 5269@cindex static probe point, DTrace
62e5f89c
SDJ
5270@value{GDBN} supports @dfn{SDT} probes in the code. @acronym{SDT} stands
5271for Statically Defined Tracing, and the probes are designed to have a tiny
3133f8c1
JM
5272runtime code and data footprint, and no dynamic relocations.
5273
5274Currently, the following types of probes are supported on
5275ELF-compatible systems:
5276
5277@itemize @bullet
62e5f89c 5278
3133f8c1
JM
5279@item @code{SystemTap} (@uref{http://sourceware.org/systemtap/})
5280@acronym{SDT} probes@footnote{See
62e5f89c 5281@uref{http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps}
3133f8c1
JM
5282for more information on how to add @code{SystemTap} @acronym{SDT}
5283probes in your applications.}. @code{SystemTap} probes are usable
5284from assembly, C and C@t{++} languages@footnote{See
5285@uref{http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation}
5286for a good reference on how the @acronym{SDT} probes are implemented.}.
5287
5288@item @code{DTrace} (@uref{http://oss.oracle.com/projects/DTrace})
5289@acronym{USDT} probes. @code{DTrace} probes are usable from C and
5290C@t{++} languages.
5291@end itemize
62e5f89c
SDJ
5292
5293@cindex semaphores on static probe points
3133f8c1
JM
5294Some @code{SystemTap} probes have an associated semaphore variable;
5295for instance, this happens automatically if you defined your probe
5296using a DTrace-style @file{.d} file. If your probe has a semaphore,
5297@value{GDBN} will automatically enable it when you specify a
5298breakpoint using the @samp{-probe-stap} notation. But, if you put a
5299breakpoint at a probe's location by some other method (e.g.,
5300@code{break file:line}), then @value{GDBN} will not automatically set
5301the semaphore. @code{DTrace} probes do not support semaphores.
62e5f89c
SDJ
5302
5303You can examine the available static static probes using @code{info
5304probes}, with optional arguments:
5305
5306@table @code
5307@kindex info probes
3133f8c1
JM
5308@item info probes @r{[}@var{type}@r{]} @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
5309If given, @var{type} is either @code{stap} for listing
5310@code{SystemTap} probes or @code{dtrace} for listing @code{DTrace}
5311probes. If omitted all probes are listed regardless of their types.
5312
62e5f89c
SDJ
5313If given, @var{provider} is a regular expression used to match against provider
5314names when selecting which probes to list. If omitted, probes by all
5315probes from all providers are listed.
5316
5317If given, @var{name} is a regular expression to match against probe names
5318when selecting which probes to list. If omitted, probe names are not
5319considered when deciding whether to display them.
5320
5321If given, @var{objfile} is a regular expression used to select which
5322object files (executable or shared libraries) to examine. If not
5323given, all object files are considered.
5324
5325@item info probes all
5326List the available static probes, from all types.
5327@end table
5328
9aca2ff8
JM
5329@cindex enabling and disabling probes
5330Some probe points can be enabled and/or disabled. The effect of
5331enabling or disabling a probe depends on the type of probe being
3133f8c1
JM
5332handled. Some @code{DTrace} probes can be enabled or
5333disabled, but @code{SystemTap} probes cannot be disabled.
9aca2ff8
JM
5334
5335You can enable (or disable) one or more probes using the following
5336commands, with optional arguments:
5337
5338@table @code
5339@kindex enable probes
5340@item enable probes @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
5341If given, @var{provider} is a regular expression used to match against
5342provider names when selecting which probes to enable. If omitted,
5343all probes from all providers are enabled.
5344
5345If given, @var{name} is a regular expression to match against probe
5346names when selecting which probes to enable. If omitted, probe names
5347are not considered when deciding whether to enable them.
5348
5349If given, @var{objfile} is a regular expression used to select which
5350object files (executable or shared libraries) to examine. If not
5351given, all object files are considered.
5352
5353@kindex disable probes
5354@item disable probes @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
5355See the @code{enable probes} command above for a description of the
5356optional arguments accepted by this command.
5357@end table
5358
62e5f89c
SDJ
5359@vindex $_probe_arg@r{, convenience variable}
5360A probe may specify up to twelve arguments. These are available at the
5361point at which the probe is defined---that is, when the current PC is
5362at the probe's location. The arguments are available using the
5363convenience variables (@pxref{Convenience Vars})
3133f8c1
JM
5364@code{$_probe_arg0}@dots{}@code{$_probe_arg11}. In @code{SystemTap}
5365probes each probe argument is an integer of the appropriate size;
5366types are not preserved. In @code{DTrace} probes types are preserved
5367provided that they are recognized as such by @value{GDBN}; otherwise
5368the value of the probe argument will be a long integer. The
62e5f89c
SDJ
5369convenience variable @code{$_probe_argc} holds the number of arguments
5370at the current probe point.
5371
5372These variables are always available, but attempts to access them at
5373any location other than a probe point will cause @value{GDBN} to give
5374an error message.
5375
5376
c906108c 5377@c @ifclear BARETARGET
6d2ebf8b 5378@node Error in Breakpoints
d4f3574e 5379@subsection ``Cannot insert breakpoints''
c906108c 5380
fa3a767f
PA
5381If you request too many active hardware-assisted breakpoints and
5382watchpoints, you will see this error message:
d4f3574e
SS
5383
5384@c FIXME: the precise wording of this message may change; the relevant
5385@c source change is not committed yet (Sep 3, 1999).
5386@smallexample
5387Stopped; cannot insert breakpoints.
5388You may have requested too many hardware breakpoints and watchpoints.
5389@end smallexample
5390
5391@noindent
5392This message is printed when you attempt to resume the program, since
5393only then @value{GDBN} knows exactly how many hardware breakpoints and
5394watchpoints it needs to insert.
5395
5396When this message is printed, you need to disable or remove some of the
5397hardware-assisted breakpoints and watchpoints, and then continue.
5398
79a6e687 5399@node Breakpoint-related Warnings
1485d690
KB
5400@subsection ``Breakpoint address adjusted...''
5401@cindex breakpoint address adjusted
5402
5403Some processor architectures place constraints on the addresses at
5404which breakpoints may be placed. For architectures thus constrained,
5405@value{GDBN} will attempt to adjust the breakpoint's address to comply
5406with the constraints dictated by the architecture.
5407
5408One example of such an architecture is the Fujitsu FR-V. The FR-V is
5409a VLIW architecture in which a number of RISC-like instructions may be
5410bundled together for parallel execution. The FR-V architecture
5411constrains the location of a breakpoint instruction within such a
5412bundle to the instruction with the lowest address. @value{GDBN}
5413honors this constraint by adjusting a breakpoint's address to the
5414first in the bundle.
5415
5416It is not uncommon for optimized code to have bundles which contain
5417instructions from different source statements, thus it may happen that
5418a breakpoint's address will be adjusted from one source statement to
5419another. Since this adjustment may significantly alter @value{GDBN}'s
5420breakpoint related behavior from what the user expects, a warning is
5421printed when the breakpoint is first set and also when the breakpoint
5422is hit.
5423
5424A warning like the one below is printed when setting a breakpoint
5425that's been subject to address adjustment:
5426
5427@smallexample
5428warning: Breakpoint address adjusted from 0x00010414 to 0x00010410.
5429@end smallexample
5430
5431Such warnings are printed both for user settable and @value{GDBN}'s
5432internal breakpoints. If you see one of these warnings, you should
5433verify that a breakpoint set at the adjusted address will have the
5434desired affect. If not, the breakpoint in question may be removed and
b383017d 5435other breakpoints may be set which will have the desired behavior.
1485d690
KB
5436E.g., it may be sufficient to place the breakpoint at a later
5437instruction. A conditional breakpoint may also be useful in some
5438cases to prevent the breakpoint from triggering too often.
5439
5440@value{GDBN} will also issue a warning when stopping at one of these
5441adjusted breakpoints:
5442
5443@smallexample
5444warning: Breakpoint 1 address previously adjusted from 0x00010414
5445to 0x00010410.
5446@end smallexample
5447
5448When this warning is encountered, it may be too late to take remedial
5449action except in cases where the breakpoint is hit earlier or more
5450frequently than expected.
d4f3574e 5451
6d2ebf8b 5452@node Continuing and Stepping
79a6e687 5453@section Continuing and Stepping
c906108c
SS
5454
5455@cindex stepping
5456@cindex continuing
5457@cindex resuming execution
5458@dfn{Continuing} means resuming program execution until your program
5459completes normally. In contrast, @dfn{stepping} means executing just
5460one more ``step'' of your program, where ``step'' may mean either one
5461line of source code, or one machine instruction (depending on what
7a292a7a
SS
5462particular command you use). Either when continuing or when stepping,
5463your program may stop even sooner, due to a breakpoint or a signal. (If
d4f3574e 5464it stops due to a signal, you may want to use @code{handle}, or use
e5f8a7cc
PA
5465@samp{signal 0} to resume execution (@pxref{Signals, ,Signals}),
5466or you may step into the signal's handler (@pxref{stepping and signal
5467handlers}).)
c906108c
SS
5468
5469@table @code
5470@kindex continue
41afff9a
EZ
5471@kindex c @r{(@code{continue})}
5472@kindex fg @r{(resume foreground execution)}
c906108c
SS
5473@item continue @r{[}@var{ignore-count}@r{]}
5474@itemx c @r{[}@var{ignore-count}@r{]}
5475@itemx fg @r{[}@var{ignore-count}@r{]}
5476Resume program execution, at the address where your program last stopped;
5477any breakpoints set at that address are bypassed. The optional argument
5478@var{ignore-count} allows you to specify a further number of times to
5479ignore a breakpoint at this location; its effect is like that of
79a6e687 5480@code{ignore} (@pxref{Conditions, ,Break Conditions}).
c906108c
SS
5481
5482The argument @var{ignore-count} is meaningful only when your program
5483stopped due to a breakpoint. At other times, the argument to
5484@code{continue} is ignored.
5485
d4f3574e
SS
5486The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the
5487debugged program is deemed to be the foreground program) are provided
5488purely for convenience, and have exactly the same behavior as
5489@code{continue}.
c906108c
SS
5490@end table
5491
5492To resume execution at a different place, you can use @code{return}
79a6e687 5493(@pxref{Returning, ,Returning from a Function}) to go back to the
c906108c 5494calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a
79a6e687 5495Different Address}) to go to an arbitrary location in your program.
c906108c
SS
5496
5497A typical technique for using stepping is to set a breakpoint
79a6e687 5498(@pxref{Breakpoints, ,Breakpoints; Watchpoints; and Catchpoints}) at the
c906108c
SS
5499beginning of the function or the section of your program where a problem
5500is believed to lie, run your program until it stops at that breakpoint,
5501and then step through the suspect area, examining the variables that are
5502interesting, until you see the problem happen.
5503
5504@table @code
5505@kindex step
41afff9a 5506@kindex s @r{(@code{step})}
c906108c
SS
5507@item step
5508Continue running your program until control reaches a different source
5509line, then stop it and return control to @value{GDBN}. This command is
5510abbreviated @code{s}.
5511
5512@quotation
5513@c "without debugging information" is imprecise; actually "without line
5514@c numbers in the debugging information". (gcc -g1 has debugging info but
5515@c not line numbers). But it seems complex to try to make that
5516@c distinction here.
5517@emph{Warning:} If you use the @code{step} command while control is
5518within a function that was compiled without debugging information,
5519execution proceeds until control reaches a function that does have
5520debugging information. Likewise, it will not step into a function which
5521is compiled without debugging information. To step through functions
5522without debugging information, use the @code{stepi} command, described
5523below.
5524@end quotation
5525
4a92d011
EZ
5526The @code{step} command only stops at the first instruction of a source
5527line. This prevents the multiple stops that could otherwise occur in
5528@code{switch} statements, @code{for} loops, etc. @code{step} continues
5529to stop if a function that has debugging information is called within
5530the line. In other words, @code{step} @emph{steps inside} any functions
5531called within the line.
c906108c 5532
d4f3574e
SS
5533Also, the @code{step} command only enters a function if there is line
5534number information for the function. Otherwise it acts like the
5d161b24 5535@code{next} command. This avoids problems when using @code{cc -gl}
eb17f351 5536on @acronym{MIPS} machines. Previously, @code{step} entered subroutines if there
5d161b24 5537was any debugging information about the routine.
c906108c
SS
5538
5539@item step @var{count}
5540Continue running as in @code{step}, but do so @var{count} times. If a
7a292a7a
SS
5541breakpoint is reached, or a signal not related to stepping occurs before
5542@var{count} steps, stepping stops right away.
c906108c
SS
5543
5544@kindex next
41afff9a 5545@kindex n @r{(@code{next})}
c906108c
SS
5546@item next @r{[}@var{count}@r{]}
5547Continue to the next source line in the current (innermost) stack frame.
7a292a7a
SS
5548This is similar to @code{step}, but function calls that appear within
5549the line of code are executed without stopping. Execution stops when
5550control reaches a different line of code at the original stack level
5551that was executing when you gave the @code{next} command. This command
5552is abbreviated @code{n}.
c906108c
SS
5553
5554An argument @var{count} is a repeat count, as for @code{step}.
5555
5556
5557@c FIX ME!! Do we delete this, or is there a way it fits in with
5558@c the following paragraph? --- Vctoria
5559@c
5560@c @code{next} within a function that lacks debugging information acts like
5561@c @code{step}, but any function calls appearing within the code of the
5562@c function are executed without stopping.
5563
d4f3574e
SS
5564The @code{next} command only stops at the first instruction of a
5565source line. This prevents multiple stops that could otherwise occur in
4a92d011 5566@code{switch} statements, @code{for} loops, etc.
c906108c 5567
b90a5f51
CF
5568@kindex set step-mode
5569@item set step-mode
5570@cindex functions without line info, and stepping
5571@cindex stepping into functions with no line info
5572@itemx set step-mode on
4a92d011 5573The @code{set step-mode on} command causes the @code{step} command to
b90a5f51
CF
5574stop at the first instruction of a function which contains no debug line
5575information rather than stepping over it.
5576
4a92d011
EZ
5577This is useful in cases where you may be interested in inspecting the
5578machine instructions of a function which has no symbolic info and do not
5579want @value{GDBN} to automatically skip over this function.
b90a5f51
CF
5580
5581@item set step-mode off
4a92d011 5582Causes the @code{step} command to step over any functions which contains no
b90a5f51
CF
5583debug information. This is the default.
5584
9c16f35a
EZ
5585@item show step-mode
5586Show whether @value{GDBN} will stop in or step over functions without
5587source line debug information.
5588
c906108c 5589@kindex finish
8dfa32fc 5590@kindex fin @r{(@code{finish})}
c906108c
SS
5591@item finish
5592Continue running until just after function in the selected stack frame
8dfa32fc
JB
5593returns. Print the returned value (if any). This command can be
5594abbreviated as @code{fin}.
c906108c
SS
5595
5596Contrast this with the @code{return} command (@pxref{Returning,
79a6e687 5597,Returning from a Function}).
c906108c
SS
5598
5599@kindex until
41afff9a 5600@kindex u @r{(@code{until})}
09d4efe1 5601@cindex run until specified location
c906108c
SS
5602@item until
5603@itemx u
5604Continue running until a source line past the current line, in the
5605current stack frame, is reached. This command is used to avoid single
5606stepping through a loop more than once. It is like the @code{next}
5607command, except that when @code{until} encounters a jump, it
5608automatically continues execution until the program counter is greater
5609than the address of the jump.
5610
5611This means that when you reach the end of a loop after single stepping
5612though it, @code{until} makes your program continue execution until it
5613exits the loop. In contrast, a @code{next} command at the end of a loop
5614simply steps back to the beginning of the loop, which forces you to step
5615through the next iteration.
5616
5617@code{until} always stops your program if it attempts to exit the current
5618stack frame.
5619
5620@code{until} may produce somewhat counterintuitive results if the order
5621of machine code does not match the order of the source lines. For
5622example, in the following excerpt from a debugging session, the @code{f}
5623(@code{frame}) command shows that execution is stopped at line
5624@code{206}; yet when we use @code{until}, we get to line @code{195}:
5625
474c8240 5626@smallexample
c906108c
SS
5627(@value{GDBP}) f
5628#0 main (argc=4, argv=0xf7fffae8) at m4.c:206
5629206 expand_input();
5630(@value{GDBP}) until
5631195 for ( ; argc > 0; NEXTARG) @{
474c8240 5632@end smallexample
c906108c
SS
5633
5634This happened because, for execution efficiency, the compiler had
5635generated code for the loop closure test at the end, rather than the
5636start, of the loop---even though the test in a C @code{for}-loop is
5637written before the body of the loop. The @code{until} command appeared
5638to step back to the beginning of the loop when it advanced to this
5639expression; however, it has not really gone to an earlier
5640statement---not in terms of the actual machine code.
5641
5642@code{until} with no argument works by means of single
5643instruction stepping, and hence is slower than @code{until} with an
5644argument.
5645
5646@item until @var{location}
5647@itemx u @var{location}
697aa1b7
EZ
5648Continue running your program until either the specified @var{location} is
5649reached, or the current stack frame returns. The location is any of
2a25a5ba
EZ
5650the forms described in @ref{Specify Location}.
5651This form of the command uses temporary breakpoints, and
c60eb6f1
EZ
5652hence is quicker than @code{until} without an argument. The specified
5653location is actually reached only if it is in the current frame. This
5654implies that @code{until} can be used to skip over recursive function
5655invocations. For instance in the code below, if the current location is
5656line @code{96}, issuing @code{until 99} will execute the program up to
db2e3e2e 5657line @code{99} in the same invocation of factorial, i.e., after the inner
c60eb6f1
EZ
5658invocations have returned.
5659
5660@smallexample
566194 int factorial (int value)
566295 @{
566396 if (value > 1) @{
566497 value *= factorial (value - 1);
566598 @}
566699 return (value);
5667100 @}
5668@end smallexample
5669
5670
5671@kindex advance @var{location}
984359d2 5672@item advance @var{location}
09d4efe1 5673Continue running the program up to the given @var{location}. An argument is
2a25a5ba
EZ
5674required, which should be of one of the forms described in
5675@ref{Specify Location}.
5676Execution will also stop upon exit from the current stack
c60eb6f1
EZ
5677frame. This command is similar to @code{until}, but @code{advance} will
5678not skip over recursive function calls, and the target location doesn't
5679have to be in the same frame as the current one.
5680
c906108c
SS
5681
5682@kindex stepi
41afff9a 5683@kindex si @r{(@code{stepi})}
c906108c 5684@item stepi
96a2c332 5685@itemx stepi @var{arg}
c906108c
SS
5686@itemx si
5687Execute one machine instruction, then stop and return to the debugger.
5688
5689It is often useful to do @samp{display/i $pc} when stepping by machine
5690instructions. This makes @value{GDBN} automatically display the next
5691instruction to be executed, each time your program stops. @xref{Auto
79a6e687 5692Display,, Automatic Display}.
c906108c
SS
5693
5694An argument is a repeat count, as in @code{step}.
5695
5696@need 750
5697@kindex nexti
41afff9a 5698@kindex ni @r{(@code{nexti})}
c906108c 5699@item nexti
96a2c332 5700@itemx nexti @var{arg}
c906108c
SS
5701@itemx ni
5702Execute one machine instruction, but if it is a function call,
5703proceed until the function returns.
5704
5705An argument is a repeat count, as in @code{next}.
c1e36e3e
PA
5706
5707@end table
5708
5709@anchor{range stepping}
5710@cindex range stepping
5711@cindex target-assisted range stepping
5712By default, and if available, @value{GDBN} makes use of
5713target-assisted @dfn{range stepping}. In other words, whenever you
5714use a stepping command (e.g., @code{step}, @code{next}), @value{GDBN}
5715tells the target to step the corresponding range of instruction
5716addresses instead of issuing multiple single-steps. This speeds up
5717line stepping, particularly for remote targets. Ideally, there should
5718be no reason you would want to turn range stepping off. However, it's
5719possible that a bug in the debug info, a bug in the remote stub (for
5720remote targets), or even a bug in @value{GDBN} could make line
5721stepping behave incorrectly when target-assisted range stepping is
5722enabled. You can use the following command to turn off range stepping
5723if necessary:
5724
5725@table @code
5726@kindex set range-stepping
5727@kindex show range-stepping
5728@item set range-stepping
5729@itemx show range-stepping
5730Control whether range stepping is enabled.
5731
5732If @code{on}, and the target supports it, @value{GDBN} tells the
5733target to step a range of addresses itself, instead of issuing
5734multiple single-steps. If @code{off}, @value{GDBN} always issues
5735single-steps, even if range stepping is supported by the target. The
5736default is @code{on}.
5737
c906108c
SS
5738@end table
5739
aad1c02c
TT
5740@node Skipping Over Functions and Files
5741@section Skipping Over Functions and Files
1bfeeb0f
JL
5742@cindex skipping over functions and files
5743
5744The program you are debugging may contain some functions which are
8244c20d 5745uninteresting to debug. The @code{skip} command lets you tell @value{GDBN} to
cce0e923
DE
5746skip a function, all functions in a file or a particular function in
5747a particular file when stepping.
1bfeeb0f
JL
5748
5749For example, consider the following C function:
5750
5751@smallexample
5752101 int func()
5753102 @{
5754103 foo(boring());
5755104 bar(boring());
5756105 @}
5757@end smallexample
5758
5759@noindent
5760Suppose you wish to step into the functions @code{foo} and @code{bar}, but you
5761are not interested in stepping through @code{boring}. If you run @code{step}
5762at line 103, you'll enter @code{boring()}, but if you run @code{next}, you'll
5763step over both @code{foo} and @code{boring}!
5764
5765One solution is to @code{step} into @code{boring} and use the @code{finish}
5766command to immediately exit it. But this can become tedious if @code{boring}
5767is called from many places.
5768
5769A more flexible solution is to execute @kbd{skip boring}. This instructs
5770@value{GDBN} never to step into @code{boring}. Now when you execute
5771@code{step} at line 103, you'll step over @code{boring} and directly into
5772@code{foo}.
5773
cce0e923
DE
5774Functions may be skipped by providing either a function name, linespec
5775(@pxref{Specify Location}), regular expression that matches the function's
5776name, file name or a @code{glob}-style pattern that matches the file name.
5777
5778On Posix systems the form of the regular expression is
5779``Extended Regular Expressions''. See for example @samp{man 7 regex}
5780on @sc{gnu}/Linux systems. On non-Posix systems the form of the regular
5781expression is whatever is provided by the @code{regcomp} function of
5782the underlying system.
5783See for example @samp{man 7 glob} on @sc{gnu}/Linux systems for a
5784description of @code{glob}-style patterns.
5785
5786@table @code
5787@kindex skip
5788@item skip @r{[}@var{options}@r{]}
5789The basic form of the @code{skip} command takes zero or more options
5790that specify what to skip.
5791The @var{options} argument is any useful combination of the following:
1bfeeb0f
JL
5792
5793@table @code
cce0e923
DE
5794@item -file @var{file}
5795@itemx -fi @var{file}
5796Functions in @var{file} will be skipped over when stepping.
5797
5798@item -gfile @var{file-glob-pattern}
5799@itemx -gfi @var{file-glob-pattern}
5800@cindex skipping over files via glob-style patterns
5801Functions in files matching @var{file-glob-pattern} will be skipped
5802over when stepping.
5803
5804@smallexample
5805(gdb) skip -gfi utils/*.c
5806@end smallexample
5807
5808@item -function @var{linespec}
5809@itemx -fu @var{linespec}
5810Functions named by @var{linespec} or the function containing the line
5811named by @var{linespec} will be skipped over when stepping.
5812@xref{Specify Location}.
5813
5814@item -rfunction @var{regexp}
5815@itemx -rfu @var{regexp}
5816@cindex skipping over functions via regular expressions
5817Functions whose name matches @var{regexp} will be skipped over when stepping.
5818
5819This form is useful for complex function names.
5820For example, there is generally no need to step into C@t{++} @code{std::string}
5821constructors or destructors. Plus with C@t{++} templates it can be hard to
5822write out the full name of the function, and often it doesn't matter what
5823the template arguments are. Specifying the function to be skipped as a
5824regular expression makes this easier.
5825
5826@smallexample
5827(gdb) skip -rfu ^std::(allocator|basic_string)<.*>::~?\1 *\(
5828@end smallexample
5829
5830If you want to skip every templated C@t{++} constructor and destructor
5831in the @code{std} namespace you can do:
5832
5833@smallexample
5834(gdb) skip -rfu ^std::([a-zA-z0-9_]+)<.*>::~?\1 *\(
5835@end smallexample
5836@end table
5837
5838If no options are specified, the function you're currently debugging
5839will be skipped.
5840
1bfeeb0f 5841@kindex skip function
cce0e923 5842@item skip function @r{[}@var{linespec}@r{]}
1bfeeb0f
JL
5843After running this command, the function named by @var{linespec} or the
5844function containing the line named by @var{linespec} will be skipped over when
983fb131 5845stepping. @xref{Specify Location}.
1bfeeb0f
JL
5846
5847If you do not specify @var{linespec}, the function you're currently debugging
5848will be skipped.
5849
5850(If you have a function called @code{file} that you want to skip, use
5851@kbd{skip function file}.)
5852
5853@kindex skip file
5854@item skip file @r{[}@var{filename}@r{]}
5855After running this command, any function whose source lives in @var{filename}
5856will be skipped over when stepping.
5857
cce0e923
DE
5858@smallexample
5859(gdb) skip file boring.c
5860File boring.c will be skipped when stepping.
5861@end smallexample
5862
1bfeeb0f
JL
5863If you do not specify @var{filename}, functions whose source lives in the file
5864you're currently debugging will be skipped.
5865@end table
5866
5867Skips can be listed, deleted, disabled, and enabled, much like breakpoints.
5868These are the commands for managing your list of skips:
5869
5870@table @code
5871@kindex info skip
5872@item info skip @r{[}@var{range}@r{]}
5873Print details about the specified skip(s). If @var{range} is not specified,
5874print a table with details about all functions and files marked for skipping.
5875@code{info skip} prints the following information about each skip:
5876
5877@table @emph
5878@item Identifier
5879A number identifying this skip.
1bfeeb0f 5880@item Enabled or Disabled
cce0e923
DE
5881Enabled skips are marked with @samp{y}.
5882Disabled skips are marked with @samp{n}.
5883@item Glob
5884If the file name is a @samp{glob} pattern this is @samp{y}.
5885Otherwise it is @samp{n}.
5886@item File
5887The name or @samp{glob} pattern of the file to be skipped.
5888If no file is specified this is @samp{<none>}.
5889@item RE
5890If the function name is a @samp{regular expression} this is @samp{y}.
5891Otherwise it is @samp{n}.
5892@item Function
5893The name or regular expression of the function to skip.
5894If no function is specified this is @samp{<none>}.
1bfeeb0f
JL
5895@end table
5896
5897@kindex skip delete
5898@item skip delete @r{[}@var{range}@r{]}
5899Delete the specified skip(s). If @var{range} is not specified, delete all
5900skips.
5901
5902@kindex skip enable
5903@item skip enable @r{[}@var{range}@r{]}
5904Enable the specified skip(s). If @var{range} is not specified, enable all
5905skips.
5906
5907@kindex skip disable
5908@item skip disable @r{[}@var{range}@r{]}
5909Disable the specified skip(s). If @var{range} is not specified, disable all
5910skips.
5911
3e68067f
SM
5912@kindex set debug skip
5913@item set debug skip @r{[}on|off@r{]}
5914Set whether to print the debug output about skipping files and functions.
5915
5916@kindex show debug skip
5917@item show debug skip
5918Show whether the debug output about skipping files and functions is printed.
5919
1bfeeb0f
JL
5920@end table
5921
6d2ebf8b 5922@node Signals
c906108c
SS
5923@section Signals
5924@cindex signals
5925
5926A signal is an asynchronous event that can happen in a program. The
5927operating system defines the possible kinds of signals, and gives each
5928kind a name and a number. For example, in Unix @code{SIGINT} is the
c8aa23ab 5929signal a program gets when you type an interrupt character (often @kbd{Ctrl-c});
c906108c
SS
5930@code{SIGSEGV} is the signal a program gets from referencing a place in
5931memory far away from all the areas in use; @code{SIGALRM} occurs when
5932the alarm clock timer goes off (which happens only if your program has
5933requested an alarm).
5934
5935@cindex fatal signals
5936Some signals, including @code{SIGALRM}, are a normal part of the
5937functioning of your program. Others, such as @code{SIGSEGV}, indicate
d4f3574e 5938errors; these signals are @dfn{fatal} (they kill your program immediately) if the
c906108c
SS
5939program has not specified in advance some other way to handle the signal.
5940@code{SIGINT} does not indicate an error in your program, but it is normally
5941fatal so it can carry out the purpose of the interrupt: to kill the program.
5942
5943@value{GDBN} has the ability to detect any occurrence of a signal in your
5944program. You can tell @value{GDBN} in advance what to do for each kind of
5945signal.
5946
5947@cindex handling signals
24f93129
EZ
5948Normally, @value{GDBN} is set up to let the non-erroneous signals like
5949@code{SIGALRM} be silently passed to your program
5950(so as not to interfere with their role in the program's functioning)
c906108c
SS
5951but to stop your program immediately whenever an error signal happens.
5952You can change these settings with the @code{handle} command.
5953
5954@table @code
5955@kindex info signals
09d4efe1 5956@kindex info handle
c906108c 5957@item info signals
96a2c332 5958@itemx info handle
c906108c
SS
5959Print a table of all the kinds of signals and how @value{GDBN} has been told to
5960handle each one. You can use this to see the signal numbers of all
5961the defined types of signals.
5962
45ac1734
EZ
5963@item info signals @var{sig}
5964Similar, but print information only about the specified signal number.
5965
d4f3574e 5966@code{info handle} is an alias for @code{info signals}.
c906108c 5967
ab04a2af
TT
5968@item catch signal @r{[}@var{signal}@dots{} @r{|} @samp{all}@r{]}
5969Set a catchpoint for the indicated signals. @xref{Set Catchpoints},
5970for details about this command.
5971
c906108c 5972@kindex handle
45ac1734 5973@item handle @var{signal} @r{[}@var{keywords}@dots{}@r{]}
697aa1b7 5974Change the way @value{GDBN} handles signal @var{signal}. The @var{signal}
5ece1a18 5975can be the number of a signal or its name (with or without the
24f93129 5976@samp{SIG} at the beginning); a list of signal numbers of the form
5ece1a18 5977@samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the
45ac1734
EZ
5978known signals. Optional arguments @var{keywords}, described below,
5979say what change to make.
c906108c
SS
5980@end table
5981
5982@c @group
5983The keywords allowed by the @code{handle} command can be abbreviated.
5984Their full names are:
5985
5986@table @code
5987@item nostop
5988@value{GDBN} should not stop your program when this signal happens. It may
5989still print a message telling you that the signal has come in.
5990
5991@item stop
5992@value{GDBN} should stop your program when this signal happens. This implies
5993the @code{print} keyword as well.
5994
5995@item print
5996@value{GDBN} should print a message when this signal happens.
5997
5998@item noprint
5999@value{GDBN} should not mention the occurrence of the signal at all. This
6000implies the @code{nostop} keyword as well.
6001
6002@item pass
5ece1a18 6003@itemx noignore
c906108c
SS
6004@value{GDBN} should allow your program to see this signal; your program
6005can handle the signal, or else it may terminate if the signal is fatal
5ece1a18 6006and not handled. @code{pass} and @code{noignore} are synonyms.
c906108c
SS
6007
6008@item nopass
5ece1a18 6009@itemx ignore
c906108c 6010@value{GDBN} should not allow your program to see this signal.
5ece1a18 6011@code{nopass} and @code{ignore} are synonyms.
c906108c
SS
6012@end table
6013@c @end group
6014
d4f3574e
SS
6015When a signal stops your program, the signal is not visible to the
6016program until you
c906108c
SS
6017continue. Your program sees the signal then, if @code{pass} is in
6018effect for the signal in question @emph{at that time}. In other words,
6019after @value{GDBN} reports a signal, you can use the @code{handle}
6020command with @code{pass} or @code{nopass} to control whether your
6021program sees that signal when you continue.
6022
24f93129
EZ
6023The default is set to @code{nostop}, @code{noprint}, @code{pass} for
6024non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and
6025@code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the
6026erroneous signals.
6027
c906108c
SS
6028You can also use the @code{signal} command to prevent your program from
6029seeing a signal, or cause it to see a signal it normally would not see,
6030or to give it any signal at any time. For example, if your program stopped
6031due to some sort of memory reference error, you might store correct
6032values into the erroneous variables and continue, hoping to see more
6033execution; but your program would probably terminate immediately as
6034a result of the fatal signal once it saw the signal. To prevent this,
6035you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your
79a6e687 6036Program a Signal}.
c906108c 6037
e5f8a7cc
PA
6038@cindex stepping and signal handlers
6039@anchor{stepping and signal handlers}
6040
6041@value{GDBN} optimizes for stepping the mainline code. If a signal
6042that has @code{handle nostop} and @code{handle pass} set arrives while
6043a stepping command (e.g., @code{stepi}, @code{step}, @code{next}) is
6044in progress, @value{GDBN} lets the signal handler run and then resumes
6045stepping the mainline code once the signal handler returns. In other
6046words, @value{GDBN} steps over the signal handler. This prevents
6047signals that you've specified as not interesting (with @code{handle
6048nostop}) from changing the focus of debugging unexpectedly. Note that
6049the signal handler itself may still hit a breakpoint, stop for another
6050signal that has @code{handle stop} in effect, or for any other event
6051that normally results in stopping the stepping command sooner. Also
6052note that @value{GDBN} still informs you that the program received a
6053signal if @code{handle print} is set.
6054
6055@anchor{stepping into signal handlers}
6056
6057If you set @code{handle pass} for a signal, and your program sets up a
6058handler for it, then issuing a stepping command, such as @code{step}
6059or @code{stepi}, when your program is stopped due to the signal will
6060step @emph{into} the signal handler (if the target supports that).
6061
6062Likewise, if you use the @code{queue-signal} command to queue a signal
6063to be delivered to the current thread when execution of the thread
6064resumes (@pxref{Signaling, ,Giving your Program a Signal}), then a
6065stepping command will step into the signal handler.
6066
6067Here's an example, using @code{stepi} to step to the first instruction
6068of @code{SIGUSR1}'s handler:
6069
6070@smallexample
6071(@value{GDBP}) handle SIGUSR1
6072Signal Stop Print Pass to program Description
6073SIGUSR1 Yes Yes Yes User defined signal 1
6074(@value{GDBP}) c
6075Continuing.
6076
6077Program received signal SIGUSR1, User defined signal 1.
6078main () sigusr1.c:28
607928 p = 0;
6080(@value{GDBP}) si
6081sigusr1_handler () at sigusr1.c:9
60829 @{
6083@end smallexample
6084
6085The same, but using @code{queue-signal} instead of waiting for the
6086program to receive the signal first:
6087
6088@smallexample
6089(@value{GDBP}) n
609028 p = 0;
6091(@value{GDBP}) queue-signal SIGUSR1
6092(@value{GDBP}) si
6093sigusr1_handler () at sigusr1.c:9
60949 @{
6095(@value{GDBP})
6096@end smallexample
6097
4aa995e1
PA
6098@cindex extra signal information
6099@anchor{extra signal information}
6100
6101On some targets, @value{GDBN} can inspect extra signal information
6102associated with the intercepted signal, before it is actually
6103delivered to the program being debugged. This information is exported
6104by the convenience variable @code{$_siginfo}, and consists of data
6105that is passed by the kernel to the signal handler at the time of the
6106receipt of a signal. The data type of the information itself is
6107target dependent. You can see the data type using the @code{ptype
6108$_siginfo} command. On Unix systems, it typically corresponds to the
6109standard @code{siginfo_t} type, as defined in the @file{signal.h}
6110system header.
6111
6112Here's an example, on a @sc{gnu}/Linux system, printing the stray
6113referenced address that raised a segmentation fault.
6114
6115@smallexample
6116@group
6117(@value{GDBP}) continue
6118Program received signal SIGSEGV, Segmentation fault.
61190x0000000000400766 in main ()
612069 *(int *)p = 0;
6121(@value{GDBP}) ptype $_siginfo
6122type = struct @{
6123 int si_signo;
6124 int si_errno;
6125 int si_code;
6126 union @{
6127 int _pad[28];
6128 struct @{...@} _kill;
6129 struct @{...@} _timer;
6130 struct @{...@} _rt;
6131 struct @{...@} _sigchld;
6132 struct @{...@} _sigfault;
6133 struct @{...@} _sigpoll;
6134 @} _sifields;
6135@}
6136(@value{GDBP}) ptype $_siginfo._sifields._sigfault
6137type = struct @{
6138 void *si_addr;
6139@}
6140(@value{GDBP}) p $_siginfo._sifields._sigfault.si_addr
6141$1 = (void *) 0x7ffff7ff7000
6142@end group
6143@end smallexample
6144
6145Depending on target support, @code{$_siginfo} may also be writable.
6146
012b3a21
WT
6147@cindex Intel MPX boundary violations
6148@cindex boundary violations, Intel MPX
6149On some targets, a @code{SIGSEGV} can be caused by a boundary
6150violation, i.e., accessing an address outside of the allowed range.
6151In those cases @value{GDBN} may displays additional information,
6152depending on how @value{GDBN} has been told to handle the signal.
6153With @code{handle stop SIGSEGV}, @value{GDBN} displays the violation
6154kind: "Upper" or "Lower", the memory address accessed and the
6155bounds, while with @code{handle nostop SIGSEGV} no additional
6156information is displayed.
6157
6158The usual output of a segfault is:
6159@smallexample
6160Program received signal SIGSEGV, Segmentation fault
61610x0000000000400d7c in upper () at i386-mpx-sigsegv.c:68
616268 value = *(p + len);
6163@end smallexample
6164
6165While a bound violation is presented as:
6166@smallexample
6167Program received signal SIGSEGV, Segmentation fault
6168Upper bound violation while accessing address 0x7fffffffc3b3
6169Bounds: [lower = 0x7fffffffc390, upper = 0x7fffffffc3a3]
61700x0000000000400d7c in upper () at i386-mpx-sigsegv.c:68
617168 value = *(p + len);
6172@end smallexample
6173
6d2ebf8b 6174@node Thread Stops
79a6e687 6175@section Stopping and Starting Multi-thread Programs
c906108c 6176
0606b73b
SL
6177@cindex stopped threads
6178@cindex threads, stopped
6179
6180@cindex continuing threads
6181@cindex threads, continuing
6182
6183@value{GDBN} supports debugging programs with multiple threads
6184(@pxref{Threads,, Debugging Programs with Multiple Threads}). There
6185are two modes of controlling execution of your program within the
6186debugger. In the default mode, referred to as @dfn{all-stop mode},
6187when any thread in your program stops (for example, at a breakpoint
6188or while being stepped), all other threads in the program are also stopped by
6189@value{GDBN}. On some targets, @value{GDBN} also supports
6190@dfn{non-stop mode}, in which other threads can continue to run freely while
6191you examine the stopped thread in the debugger.
6192
6193@menu
6194* All-Stop Mode:: All threads stop when GDB takes control
6195* Non-Stop Mode:: Other threads continue to execute
6196* Background Execution:: Running your program asynchronously
6197* Thread-Specific Breakpoints:: Controlling breakpoints
6198* Interrupted System Calls:: GDB may interfere with system calls
d914c394 6199* Observer Mode:: GDB does not alter program behavior
0606b73b
SL
6200@end menu
6201
6202@node All-Stop Mode
6203@subsection All-Stop Mode
6204
6205@cindex all-stop mode
6206
6207In all-stop mode, whenever your program stops under @value{GDBN} for any reason,
6208@emph{all} threads of execution stop, not just the current thread. This
6209allows you to examine the overall state of the program, including
6210switching between threads, without worrying that things may change
6211underfoot.
6212
6213Conversely, whenever you restart the program, @emph{all} threads start
6214executing. @emph{This is true even when single-stepping} with commands
6215like @code{step} or @code{next}.
6216
6217In particular, @value{GDBN} cannot single-step all threads in lockstep.
6218Since thread scheduling is up to your debugging target's operating
6219system (not controlled by @value{GDBN}), other threads may
6220execute more than one statement while the current thread completes a
6221single step. Moreover, in general other threads stop in the middle of a
6222statement, rather than at a clean statement boundary, when the program
6223stops.
6224
6225You might even find your program stopped in another thread after
6226continuing or even single-stepping. This happens whenever some other
6227thread runs into a breakpoint, a signal, or an exception before the
6228first thread completes whatever you requested.
6229
6230@cindex automatic thread selection
6231@cindex switching threads automatically
6232@cindex threads, automatic switching
6233Whenever @value{GDBN} stops your program, due to a breakpoint or a
6234signal, it automatically selects the thread where that breakpoint or
6235signal happened. @value{GDBN} alerts you to the context switch with a
6236message such as @samp{[Switching to Thread @var{n}]} to identify the
6237thread.
6238
6239On some OSes, you can modify @value{GDBN}'s default behavior by
6240locking the OS scheduler to allow only a single thread to run.
6241
6242@table @code
6243@item set scheduler-locking @var{mode}
6244@cindex scheduler locking mode
6245@cindex lock scheduler
f2665db5
MM
6246Set the scheduler locking mode. It applies to normal execution,
6247record mode, and replay mode. If it is @code{off}, then there is no
6248locking and any thread may run at any time. If @code{on}, then only
6249the current thread may run when the inferior is resumed. The
6250@code{step} mode optimizes for single-stepping; it prevents other
6251threads from preempting the current thread while you are stepping, so
6252that the focus of debugging does not change unexpectedly. Other
6253threads never get a chance to run when you step, and they are
6254completely free to run when you use commands like @samp{continue},
6255@samp{until}, or @samp{finish}. However, unless another thread hits a
6256breakpoint during its timeslice, @value{GDBN} does not change the
6257current thread away from the thread that you are debugging. The
6258@code{replay} mode behaves like @code{off} in record mode and like
6259@code{on} in replay mode.
0606b73b
SL
6260
6261@item show scheduler-locking
6262Display the current scheduler locking mode.
6263@end table
6264
d4db2f36
PA
6265@cindex resume threads of multiple processes simultaneously
6266By default, when you issue one of the execution commands such as
6267@code{continue}, @code{next} or @code{step}, @value{GDBN} allows only
6268threads of the current inferior to run. For example, if @value{GDBN}
6269is attached to two inferiors, each with two threads, the
6270@code{continue} command resumes only the two threads of the current
6271inferior. This is useful, for example, when you debug a program that
6272forks and you want to hold the parent stopped (so that, for instance,
6273it doesn't run to exit), while you debug the child. In other
6274situations, you may not be interested in inspecting the current state
6275of any of the processes @value{GDBN} is attached to, and you may want
6276to resume them all until some breakpoint is hit. In the latter case,
6277you can instruct @value{GDBN} to allow all threads of all the
6278inferiors to run with the @w{@code{set schedule-multiple}} command.
6279
6280@table @code
6281@kindex set schedule-multiple
6282@item set schedule-multiple
6283Set the mode for allowing threads of multiple processes to be resumed
6284when an execution command is issued. When @code{on}, all threads of
6285all processes are allowed to run. When @code{off}, only the threads
6286of the current process are resumed. The default is @code{off}. The
6287@code{scheduler-locking} mode takes precedence when set to @code{on},
6288or while you are stepping and set to @code{step}.
6289
6290@item show schedule-multiple
6291Display the current mode for resuming the execution of threads of
6292multiple processes.
6293@end table
6294
0606b73b
SL
6295@node Non-Stop Mode
6296@subsection Non-Stop Mode
6297
6298@cindex non-stop mode
6299
6300@c This section is really only a place-holder, and needs to be expanded
97d8f0ee 6301@c with more details.
0606b73b
SL
6302
6303For some multi-threaded targets, @value{GDBN} supports an optional
6304mode of operation in which you can examine stopped program threads in
6305the debugger while other threads continue to execute freely. This
97d8f0ee
DE
6306minimizes intrusion when debugging live systems, such as programs
6307where some threads have real-time constraints or must continue to
0606b73b
SL
6308respond to external events. This is referred to as @dfn{non-stop} mode.
6309
6310In non-stop mode, when a thread stops to report a debugging event,
6311@emph{only} that thread is stopped; @value{GDBN} does not stop other
6312threads as well, in contrast to the all-stop mode behavior. Additionally,
6313execution commands such as @code{continue} and @code{step} apply by default
6314only to the current thread in non-stop mode, rather than all threads as
6315in all-stop mode. This allows you to control threads explicitly in
97d8f0ee 6316ways that are not possible in all-stop mode --- for example, stepping
0606b73b 6317one thread while allowing others to run freely, stepping
97d8f0ee 6318one thread while holding all others stopped, or stepping several threads
0606b73b
SL
6319independently and simultaneously.
6320
6321To enter non-stop mode, use this sequence of commands before you run
6322or attach to your program:
6323
0606b73b 6324@smallexample
0606b73b
SL
6325# If using the CLI, pagination breaks non-stop.
6326set pagination off
6327
6328# Finally, turn it on!
6329set non-stop on
6330@end smallexample
6331
6332You can use these commands to manipulate the non-stop mode setting:
6333
6334@table @code
6335@kindex set non-stop
6336@item set non-stop on
6337Enable selection of non-stop mode.
6338@item set non-stop off
6339Disable selection of non-stop mode.
6340@kindex show non-stop
6341@item show non-stop
6342Show the current non-stop enablement setting.
6343@end table
6344
6345Note these commands only reflect whether non-stop mode is enabled,
97d8f0ee 6346not whether the currently-executing program is being run in non-stop mode.
0606b73b 6347In particular, the @code{set non-stop} preference is only consulted when
97d8f0ee 6348@value{GDBN} starts or connects to the target program, and it is generally
0606b73b
SL
6349not possible to switch modes once debugging has started. Furthermore,
6350since not all targets support non-stop mode, even when you have enabled
6351non-stop mode, @value{GDBN} may still fall back to all-stop operation by
6352default.
6353
6354In non-stop mode, all execution commands apply only to the current thread
97d8f0ee 6355by default. That is, @code{continue} only continues one thread.
0606b73b
SL
6356To continue all threads, issue @code{continue -a} or @code{c -a}.
6357
97d8f0ee 6358You can use @value{GDBN}'s background execution commands
0606b73b 6359(@pxref{Background Execution}) to run some threads in the background
97d8f0ee 6360while you continue to examine or step others from @value{GDBN}.
0606b73b
SL
6361The MI execution commands (@pxref{GDB/MI Program Execution}) are
6362always executed asynchronously in non-stop mode.
6363
6364Suspending execution is done with the @code{interrupt} command when
97d8f0ee
DE
6365running in the background, or @kbd{Ctrl-c} during foreground execution.
6366In all-stop mode, this stops the whole process;
6367but in non-stop mode the interrupt applies only to the current thread.
0606b73b
SL
6368To stop the whole program, use @code{interrupt -a}.
6369
6370Other execution commands do not currently support the @code{-a} option.
6371
6372In non-stop mode, when a thread stops, @value{GDBN} doesn't automatically make
6373that thread current, as it does in all-stop mode. This is because the
97d8f0ee 6374thread stop notifications are asynchronous with respect to @value{GDBN}'s
0606b73b
SL
6375command interpreter, and it would be confusing if @value{GDBN} unexpectedly
6376changed to a different thread just as you entered a command to operate on the
6377previously current thread.
6378
6379@node Background Execution
6380@subsection Background Execution
6381
6382@cindex foreground execution
6383@cindex background execution
6384@cindex asynchronous execution
6385@cindex execution, foreground, background and asynchronous
6386
6387@value{GDBN}'s execution commands have two variants: the normal
6388foreground (synchronous) behavior, and a background
97d8f0ee 6389(asynchronous) behavior. In foreground execution, @value{GDBN} waits for
0606b73b
SL
6390the program to report that some thread has stopped before prompting for
6391another command. In background execution, @value{GDBN} immediately gives
6392a command prompt so that you can issue other commands while your program runs.
6393
32fc0df9
PA
6394If the target doesn't support async mode, @value{GDBN} issues an error
6395message if you attempt to use the background execution commands.
6396
74fdb8ff 6397@cindex @code{&}, background execution of commands
0606b73b
SL
6398To specify background execution, add a @code{&} to the command. For example,
6399the background form of the @code{continue} command is @code{continue&}, or
6400just @code{c&}. The execution commands that accept background execution
6401are:
6402
6403@table @code
6404@kindex run&
6405@item run
6406@xref{Starting, , Starting your Program}.
6407
6408@item attach
6409@kindex attach&
6410@xref{Attach, , Debugging an Already-running Process}.
6411
6412@item step
6413@kindex step&
6414@xref{Continuing and Stepping, step}.
6415
6416@item stepi
6417@kindex stepi&
6418@xref{Continuing and Stepping, stepi}.
6419
6420@item next
6421@kindex next&
6422@xref{Continuing and Stepping, next}.
6423
7ce58dd2
DE
6424@item nexti
6425@kindex nexti&
6426@xref{Continuing and Stepping, nexti}.
6427
0606b73b
SL
6428@item continue
6429@kindex continue&
6430@xref{Continuing and Stepping, continue}.
6431
6432@item finish
6433@kindex finish&
6434@xref{Continuing and Stepping, finish}.
6435
6436@item until
6437@kindex until&
6438@xref{Continuing and Stepping, until}.
6439
6440@end table
6441
6442Background execution is especially useful in conjunction with non-stop
6443mode for debugging programs with multiple threads; see @ref{Non-Stop Mode}.
6444However, you can also use these commands in the normal all-stop mode with
6445the restriction that you cannot issue another execution command until the
6446previous one finishes. Examples of commands that are valid in all-stop
6447mode while the program is running include @code{help} and @code{info break}.
6448
6449You can interrupt your program while it is running in the background by
6450using the @code{interrupt} command.
6451
6452@table @code
6453@kindex interrupt
6454@item interrupt
6455@itemx interrupt -a
6456
97d8f0ee 6457Suspend execution of the running program. In all-stop mode,
0606b73b 6458@code{interrupt} stops the whole process, but in non-stop mode, it stops
97d8f0ee 6459only the current thread. To stop the whole program in non-stop mode,
0606b73b
SL
6460use @code{interrupt -a}.
6461@end table
6462
0606b73b
SL
6463@node Thread-Specific Breakpoints
6464@subsection Thread-Specific Breakpoints
6465
c906108c 6466When your program has multiple threads (@pxref{Threads,, Debugging
79a6e687 6467Programs with Multiple Threads}), you can choose whether to set
c906108c
SS
6468breakpoints on all threads, or on a particular thread.
6469
6470@table @code
6471@cindex breakpoints and threads
6472@cindex thread breakpoints
5d5658a1
PA
6473@kindex break @dots{} thread @var{thread-id}
6474@item break @var{location} thread @var{thread-id}
6475@itemx break @var{location} thread @var{thread-id} if @dots{}
629500fa 6476@var{location} specifies source lines; there are several ways of
2a25a5ba
EZ
6477writing them (@pxref{Specify Location}), but the effect is always to
6478specify some source line.
c906108c 6479
5d5658a1 6480Use the qualifier @samp{thread @var{thread-id}} with a breakpoint command
c906108c 6481to specify that you only want @value{GDBN} to stop the program when a
5d5658a1
PA
6482particular thread reaches this breakpoint. The @var{thread-id} specifier
6483is one of the thread identifiers assigned by @value{GDBN}, shown
697aa1b7 6484in the first column of the @samp{info threads} display.
c906108c 6485
5d5658a1 6486If you do not specify @samp{thread @var{thread-id}} when you set a
c906108c
SS
6487breakpoint, the breakpoint applies to @emph{all} threads of your
6488program.
6489
6490You can use the @code{thread} qualifier on conditional breakpoints as
5d5658a1 6491well; in this case, place @samp{thread @var{thread-id}} before or
b6199126 6492after the breakpoint condition, like this:
c906108c
SS
6493
6494@smallexample
2df3850c 6495(@value{GDBP}) break frik.c:13 thread 28 if bartab > lim
c906108c
SS
6496@end smallexample
6497
6498@end table
6499
f4fb82a1
PA
6500Thread-specific breakpoints are automatically deleted when
6501@value{GDBN} detects the corresponding thread is no longer in the
6502thread list. For example:
6503
6504@smallexample
6505(@value{GDBP}) c
6506Thread-specific breakpoint 3 deleted - thread 28 no longer in the thread list.
6507@end smallexample
6508
6509There are several ways for a thread to disappear, such as a regular
6510thread exit, but also when you detach from the process with the
6511@code{detach} command (@pxref{Attach, ,Debugging an Already-running
6512Process}), or if @value{GDBN} loses the remote connection
6513(@pxref{Remote Debugging}), etc. Note that with some targets,
6514@value{GDBN} is only able to detect a thread has exited when the user
6515explictly asks for the thread list with the @code{info threads}
6516command.
6517
0606b73b
SL
6518@node Interrupted System Calls
6519@subsection Interrupted System Calls
c906108c 6520
36d86913
MC
6521@cindex thread breakpoints and system calls
6522@cindex system calls and thread breakpoints
6523@cindex premature return from system calls
0606b73b
SL
6524There is an unfortunate side effect when using @value{GDBN} to debug
6525multi-threaded programs. If one thread stops for a
36d86913
MC
6526breakpoint, or for some other reason, and another thread is blocked in a
6527system call, then the system call may return prematurely. This is a
6528consequence of the interaction between multiple threads and the signals
6529that @value{GDBN} uses to implement breakpoints and other events that
6530stop execution.
6531
6532To handle this problem, your program should check the return value of
6533each system call and react appropriately. This is good programming
6534style anyways.
6535
6536For example, do not write code like this:
6537
6538@smallexample
6539 sleep (10);
6540@end smallexample
6541
6542The call to @code{sleep} will return early if a different thread stops
6543at a breakpoint or for some other reason.
6544
6545Instead, write this:
6546
6547@smallexample
6548 int unslept = 10;
6549 while (unslept > 0)
6550 unslept = sleep (unslept);
6551@end smallexample
6552
6553A system call is allowed to return early, so the system is still
6554conforming to its specification. But @value{GDBN} does cause your
6555multi-threaded program to behave differently than it would without
6556@value{GDBN}.
6557
6558Also, @value{GDBN} uses internal breakpoints in the thread library to
6559monitor certain events such as thread creation and thread destruction.
6560When such an event happens, a system call in another thread may return
6561prematurely, even though your program does not appear to stop.
6562
d914c394
SS
6563@node Observer Mode
6564@subsection Observer Mode
6565
6566If you want to build on non-stop mode and observe program behavior
6567without any chance of disruption by @value{GDBN}, you can set
6568variables to disable all of the debugger's attempts to modify state,
6569whether by writing memory, inserting breakpoints, etc. These operate
6570at a low level, intercepting operations from all commands.
6571
6572When all of these are set to @code{off}, then @value{GDBN} is said to
6573be @dfn{observer mode}. As a convenience, the variable
6574@code{observer} can be set to disable these, plus enable non-stop
6575mode.
6576
6577Note that @value{GDBN} will not prevent you from making nonsensical
6578combinations of these settings. For instance, if you have enabled
6579@code{may-insert-breakpoints} but disabled @code{may-write-memory},
6580then breakpoints that work by writing trap instructions into the code
6581stream will still not be able to be placed.
6582
6583@table @code
6584
6585@kindex observer
6586@item set observer on
6587@itemx set observer off
6588When set to @code{on}, this disables all the permission variables
6589below (except for @code{insert-fast-tracepoints}), plus enables
6590non-stop debugging. Setting this to @code{off} switches back to
6591normal debugging, though remaining in non-stop mode.
6592
6593@item show observer
6594Show whether observer mode is on or off.
6595
6596@kindex may-write-registers
6597@item set may-write-registers on
6598@itemx set may-write-registers off
6599This controls whether @value{GDBN} will attempt to alter the values of
6600registers, such as with assignment expressions in @code{print}, or the
6601@code{jump} command. It defaults to @code{on}.
6602
6603@item show may-write-registers
6604Show the current permission to write registers.
6605
6606@kindex may-write-memory
6607@item set may-write-memory on
6608@itemx set may-write-memory off
6609This controls whether @value{GDBN} will attempt to alter the contents
6610of memory, such as with assignment expressions in @code{print}. It
6611defaults to @code{on}.
6612
6613@item show may-write-memory
6614Show the current permission to write memory.
6615
6616@kindex may-insert-breakpoints
6617@item set may-insert-breakpoints on
6618@itemx set may-insert-breakpoints off
6619This controls whether @value{GDBN} will attempt to insert breakpoints.
6620This affects all breakpoints, including internal breakpoints defined
6621by @value{GDBN}. It defaults to @code{on}.
6622
6623@item show may-insert-breakpoints
6624Show the current permission to insert breakpoints.
6625
6626@kindex may-insert-tracepoints
6627@item set may-insert-tracepoints on
6628@itemx set may-insert-tracepoints off
6629This controls whether @value{GDBN} will attempt to insert (regular)
6630tracepoints at the beginning of a tracing experiment. It affects only
6631non-fast tracepoints, fast tracepoints being under the control of
6632@code{may-insert-fast-tracepoints}. It defaults to @code{on}.
6633
6634@item show may-insert-tracepoints
6635Show the current permission to insert tracepoints.
6636
6637@kindex may-insert-fast-tracepoints
6638@item set may-insert-fast-tracepoints on
6639@itemx set may-insert-fast-tracepoints off
6640This controls whether @value{GDBN} will attempt to insert fast
6641tracepoints at the beginning of a tracing experiment. It affects only
6642fast tracepoints, regular (non-fast) tracepoints being under the
6643control of @code{may-insert-tracepoints}. It defaults to @code{on}.
6644
6645@item show may-insert-fast-tracepoints
6646Show the current permission to insert fast tracepoints.
6647
6648@kindex may-interrupt
6649@item set may-interrupt on
6650@itemx set may-interrupt off
6651This controls whether @value{GDBN} will attempt to interrupt or stop
6652program execution. When this variable is @code{off}, the
6653@code{interrupt} command will have no effect, nor will
6654@kbd{Ctrl-c}. It defaults to @code{on}.
6655
6656@item show may-interrupt
6657Show the current permission to interrupt or stop the program.
6658
6659@end table
c906108c 6660
bacec72f
MS
6661@node Reverse Execution
6662@chapter Running programs backward
6663@cindex reverse execution
6664@cindex running programs backward
6665
6666When you are debugging a program, it is not unusual to realize that
6667you have gone too far, and some event of interest has already happened.
6668If the target environment supports it, @value{GDBN} can allow you to
6669``rewind'' the program by running it backward.
6670
6671A target environment that supports reverse execution should be able
6672to ``undo'' the changes in machine state that have taken place as the
6673program was executing normally. Variables, registers etc.@: should
6674revert to their previous values. Obviously this requires a great
6675deal of sophistication on the part of the target environment; not
6676all target environments can support reverse execution.
6677
6678When a program is executed in reverse, the instructions that
6679have most recently been executed are ``un-executed'', in reverse
6680order. The program counter runs backward, following the previous
6681thread of execution in reverse. As each instruction is ``un-executed'',
6682the values of memory and/or registers that were changed by that
6683instruction are reverted to their previous states. After executing
6684a piece of source code in reverse, all side effects of that code
6685should be ``undone'', and all variables should be returned to their
6686prior values@footnote{
6687Note that some side effects are easier to undo than others. For instance,
6688memory and registers are relatively easy, but device I/O is hard. Some
6689targets may be able undo things like device I/O, and some may not.
6690
6691The contract between @value{GDBN} and the reverse executing target
6692requires only that the target do something reasonable when
6693@value{GDBN} tells it to execute backwards, and then report the
6694results back to @value{GDBN}. Whatever the target reports back to
6695@value{GDBN}, @value{GDBN} will report back to the user. @value{GDBN}
6696assumes that the memory and registers that the target reports are in a
6697consistant state, but @value{GDBN} accepts whatever it is given.
6698}.
6699
6700If you are debugging in a target environment that supports
6701reverse execution, @value{GDBN} provides the following commands.
6702
6703@table @code
6704@kindex reverse-continue
6705@kindex rc @r{(@code{reverse-continue})}
6706@item reverse-continue @r{[}@var{ignore-count}@r{]}
6707@itemx rc @r{[}@var{ignore-count}@r{]}
6708Beginning at the point where your program last stopped, start executing
6709in reverse. Reverse execution will stop for breakpoints and synchronous
6710exceptions (signals), just like normal execution. Behavior of
6711asynchronous signals depends on the target environment.
6712
6713@kindex reverse-step
6714@kindex rs @r{(@code{step})}
6715@item reverse-step @r{[}@var{count}@r{]}
6716Run the program backward until control reaches the start of a
6717different source line; then stop it, and return control to @value{GDBN}.
6718
6719Like the @code{step} command, @code{reverse-step} will only stop
6720at the beginning of a source line. It ``un-executes'' the previously
6721executed source line. If the previous source line included calls to
6722debuggable functions, @code{reverse-step} will step (backward) into
6723the called function, stopping at the beginning of the @emph{last}
6724statement in the called function (typically a return statement).
6725
6726Also, as with the @code{step} command, if non-debuggable functions are
6727called, @code{reverse-step} will run thru them backward without stopping.
6728
6729@kindex reverse-stepi
6730@kindex rsi @r{(@code{reverse-stepi})}
6731@item reverse-stepi @r{[}@var{count}@r{]}
6732Reverse-execute one machine instruction. Note that the instruction
6733to be reverse-executed is @emph{not} the one pointed to by the program
6734counter, but the instruction executed prior to that one. For instance,
6735if the last instruction was a jump, @code{reverse-stepi} will take you
6736back from the destination of the jump to the jump instruction itself.
6737
6738@kindex reverse-next
6739@kindex rn @r{(@code{reverse-next})}
6740@item reverse-next @r{[}@var{count}@r{]}
6741Run backward to the beginning of the previous line executed in
6742the current (innermost) stack frame. If the line contains function
6743calls, they will be ``un-executed'' without stopping. Starting from
6744the first line of a function, @code{reverse-next} will take you back
6745to the caller of that function, @emph{before} the function was called,
6746just as the normal @code{next} command would take you from the last
6747line of a function back to its return to its caller
16af530a 6748@footnote{Unless the code is too heavily optimized.}.
bacec72f
MS
6749
6750@kindex reverse-nexti
6751@kindex rni @r{(@code{reverse-nexti})}
6752@item reverse-nexti @r{[}@var{count}@r{]}
6753Like @code{nexti}, @code{reverse-nexti} executes a single instruction
6754in reverse, except that called functions are ``un-executed'' atomically.
6755That is, if the previously executed instruction was a return from
540aa8e7 6756another function, @code{reverse-nexti} will continue to execute
bacec72f
MS
6757in reverse until the call to that function (from the current stack
6758frame) is reached.
6759
6760@kindex reverse-finish
6761@item reverse-finish
6762Just as the @code{finish} command takes you to the point where the
6763current function returns, @code{reverse-finish} takes you to the point
6764where it was called. Instead of ending up at the end of the current
6765function invocation, you end up at the beginning.
6766
6767@kindex set exec-direction
6768@item set exec-direction
6769Set the direction of target execution.
984359d2 6770@item set exec-direction reverse
bacec72f
MS
6771@cindex execute forward or backward in time
6772@value{GDBN} will perform all execution commands in reverse, until the
6773exec-direction mode is changed to ``forward''. Affected commands include
6774@code{step, stepi, next, nexti, continue, and finish}. The @code{return}
6775command cannot be used in reverse mode.
6776@item set exec-direction forward
6777@value{GDBN} will perform all execution commands in the normal fashion.
6778This is the default.
6779@end table
6780
c906108c 6781
a2311334
EZ
6782@node Process Record and Replay
6783@chapter Recording Inferior's Execution and Replaying It
53cc454a
HZ
6784@cindex process record and replay
6785@cindex recording inferior's execution and replaying it
6786
8e05493c
EZ
6787On some platforms, @value{GDBN} provides a special @dfn{process record
6788and replay} target that can record a log of the process execution, and
6789replay it later with both forward and reverse execution commands.
a2311334
EZ
6790
6791@cindex replay mode
6792When this target is in use, if the execution log includes the record
6793for the next instruction, @value{GDBN} will debug in @dfn{replay
6794mode}. In the replay mode, the inferior does not really execute code
6795instructions. Instead, all the events that normally happen during
6796code execution are taken from the execution log. While code is not
6797really executed in replay mode, the values of registers (including the
6798program counter register) and the memory of the inferior are still
8e05493c
EZ
6799changed as they normally would. Their contents are taken from the
6800execution log.
a2311334
EZ
6801
6802@cindex record mode
6803If the record for the next instruction is not in the execution log,
6804@value{GDBN} will debug in @dfn{record mode}. In this mode, the
6805inferior executes normally, and @value{GDBN} records the execution log
6806for future replay.
6807
8e05493c
EZ
6808The process record and replay target supports reverse execution
6809(@pxref{Reverse Execution}), even if the platform on which the
6810inferior runs does not. However, the reverse execution is limited in
6811this case by the range of the instructions recorded in the execution
6812log. In other words, reverse execution on platforms that don't
6813support it directly can only be done in the replay mode.
6814
6815When debugging in the reverse direction, @value{GDBN} will work in
6816replay mode as long as the execution log includes the record for the
6817previous instruction; otherwise, it will work in record mode, if the
6818platform supports reverse execution, or stop if not.
6819
a2311334
EZ
6820For architecture environments that support process record and replay,
6821@value{GDBN} provides the following commands:
53cc454a
HZ
6822
6823@table @code
6824@kindex target record
59ea5688
MM
6825@kindex target record-full
6826@kindex target record-btrace
53cc454a 6827@kindex record
59ea5688
MM
6828@kindex record full
6829@kindex record btrace
f4abbc16 6830@kindex record btrace bts
b20a6524 6831@kindex record btrace pt
f4abbc16 6832@kindex record bts
b20a6524 6833@kindex record pt
53cc454a 6834@kindex rec
59ea5688
MM
6835@kindex rec full
6836@kindex rec btrace
f4abbc16 6837@kindex rec btrace bts
b20a6524 6838@kindex rec btrace pt
f4abbc16 6839@kindex rec bts
b20a6524 6840@kindex rec pt
59ea5688
MM
6841@item record @var{method}
6842This command starts the process record and replay target. The
6843recording method can be specified as parameter. Without a parameter
6844the command uses the @code{full} recording method. The following
6845recording methods are available:
a2311334 6846
59ea5688
MM
6847@table @code
6848@item full
6849Full record/replay recording using @value{GDBN}'s software record and
6850replay implementation. This method allows replaying and reverse
6851execution.
6852
f4abbc16 6853@item btrace @var{format}
52834460
MM
6854Hardware-supported instruction recording. This method does not record
6855data. Further, the data is collected in a ring buffer so old data will
b20a6524
MM
6856be overwritten when the buffer is full. It allows limited reverse
6857execution. Variables and registers are not available during reverse
c0272db5
TW
6858execution. In remote debugging, recording continues on disconnect.
6859Recorded data can be inspected after reconnecting. The recording may
6860be stopped using @code{record stop}.
59ea5688 6861
f4abbc16
MM
6862The recording format can be specified as parameter. Without a parameter
6863the command chooses the recording format. The following recording
6864formats are available:
6865
6866@table @code
6867@item bts
6868@cindex branch trace store
6869Use the @dfn{Branch Trace Store} (@acronym{BTS}) recording format. In
6870this format, the processor stores a from/to record for each executed
6871branch in the btrace ring buffer.
b20a6524
MM
6872
6873@item pt
bc504a31
PA
6874@cindex Intel Processor Trace
6875Use the @dfn{Intel Processor Trace} recording format. In this
b20a6524
MM
6876format, the processor stores the execution trace in a compressed form
6877that is afterwards decoded by @value{GDBN}.
6878
6879The trace can be recorded with very low overhead. The compressed
6880trace format also allows small trace buffers to already contain a big
6881number of instructions compared to @acronym{BTS}.
6882
6883Decoding the recorded execution trace, on the other hand, is more
6884expensive than decoding @acronym{BTS} trace. This is mostly due to the
6885increased number of instructions to process. You should increase the
6886buffer-size with care.
f4abbc16
MM
6887@end table
6888
6889Not all recording formats may be available on all processors.
59ea5688
MM
6890@end table
6891
6892The process record and replay target can only debug a process that is
6893already running. Therefore, you need first to start the process with
6894the @kbd{run} or @kbd{start} commands, and then start the recording
6895with the @kbd{record @var{method}} command.
6896
a2311334
EZ
6897@cindex displaced stepping, and process record and replay
6898Displaced stepping (@pxref{Maintenance Commands,, displaced stepping})
6899will be automatically disabled when process record and replay target
6900is started. That's because the process record and replay target
6901doesn't support displaced stepping.
6902
6903@cindex non-stop mode, and process record and replay
6904@cindex asynchronous execution, and process record and replay
6905If the inferior is in the non-stop mode (@pxref{Non-Stop Mode}) or in
59ea5688
MM
6906the asynchronous execution mode (@pxref{Background Execution}), not
6907all recording methods are available. The @code{full} recording method
6908does not support these two modes.
53cc454a
HZ
6909
6910@kindex record stop
6911@kindex rec s
6912@item record stop
a2311334
EZ
6913Stop the process record and replay target. When process record and
6914replay target stops, the entire execution log will be deleted and the
6915inferior will either be terminated, or will remain in its final state.
53cc454a 6916
a2311334
EZ
6917When you stop the process record and replay target in record mode (at
6918the end of the execution log), the inferior will be stopped at the
6919next instruction that would have been recorded. In other words, if
6920you record for a while and then stop recording, the inferior process
6921will be left in the same state as if the recording never happened.
53cc454a 6922
a2311334
EZ
6923On the other hand, if the process record and replay target is stopped
6924while in replay mode (that is, not at the end of the execution log,
6925but at some earlier point), the inferior process will become ``live''
6926at that earlier state, and it will then be possible to continue the
6927usual ``live'' debugging of the process from that state.
53cc454a 6928
a2311334
EZ
6929When the inferior process exits, or @value{GDBN} detaches from it,
6930process record and replay target will automatically stop itself.
53cc454a 6931
742ce053
MM
6932@kindex record goto
6933@item record goto
6934Go to a specific location in the execution log. There are several
6935ways to specify the location to go to:
6936
6937@table @code
6938@item record goto begin
6939@itemx record goto start
6940Go to the beginning of the execution log.
6941
6942@item record goto end
6943Go to the end of the execution log.
6944
6945@item record goto @var{n}
6946Go to instruction number @var{n} in the execution log.
6947@end table
6948
24e933df
HZ
6949@kindex record save
6950@item record save @var{filename}
6951Save the execution log to a file @file{@var{filename}}.
6952Default filename is @file{gdb_record.@var{process_id}}, where
6953@var{process_id} is the process ID of the inferior.
6954
59ea5688
MM
6955This command may not be available for all recording methods.
6956
24e933df
HZ
6957@kindex record restore
6958@item record restore @var{filename}
6959Restore the execution log from a file @file{@var{filename}}.
6960File must have been created with @code{record save}.
6961
59ea5688
MM
6962@kindex set record full
6963@item set record full insn-number-max @var{limit}
f81d1120 6964@itemx set record full insn-number-max unlimited
59ea5688
MM
6965Set the limit of instructions to be recorded for the @code{full}
6966recording method. Default value is 200000.
53cc454a 6967
a2311334
EZ
6968If @var{limit} is a positive number, then @value{GDBN} will start
6969deleting instructions from the log once the number of the record
6970instructions becomes greater than @var{limit}. For every new recorded
6971instruction, @value{GDBN} will delete the earliest recorded
6972instruction to keep the number of recorded instructions at the limit.
6973(Since deleting recorded instructions loses information, @value{GDBN}
6974lets you control what happens when the limit is reached, by means of
6975the @code{stop-at-limit} option, described below.)
53cc454a 6976
f81d1120
PA
6977If @var{limit} is @code{unlimited} or zero, @value{GDBN} will never
6978delete recorded instructions from the execution log. The number of
6979recorded instructions is limited only by the available memory.
53cc454a 6980
59ea5688
MM
6981@kindex show record full
6982@item show record full insn-number-max
6983Show the limit of instructions to be recorded with the @code{full}
6984recording method.
53cc454a 6985
59ea5688
MM
6986@item set record full stop-at-limit
6987Control the behavior of the @code{full} recording method when the
6988number of recorded instructions reaches the limit. If ON (the
6989default), @value{GDBN} will stop when the limit is reached for the
6990first time and ask you whether you want to stop the inferior or
6991continue running it and recording the execution log. If you decide
6992to continue recording, each new recorded instruction will cause the
6993oldest one to be deleted.
53cc454a 6994
a2311334
EZ
6995If this option is OFF, @value{GDBN} will automatically delete the
6996oldest record to make room for each new one, without asking.
53cc454a 6997
59ea5688 6998@item show record full stop-at-limit
a2311334 6999Show the current setting of @code{stop-at-limit}.
53cc454a 7000
59ea5688 7001@item set record full memory-query
bb08c432 7002Control the behavior when @value{GDBN} is unable to record memory
59ea5688
MM
7003changes caused by an instruction for the @code{full} recording method.
7004If ON, @value{GDBN} will query whether to stop the inferior in that
7005case.
bb08c432
HZ
7006
7007If this option is OFF (the default), @value{GDBN} will automatically
7008ignore the effect of such instructions on memory. Later, when
7009@value{GDBN} replays this execution log, it will mark the log of this
7010instruction as not accessible, and it will not affect the replay
7011results.
7012
59ea5688 7013@item show record full memory-query
bb08c432
HZ
7014Show the current setting of @code{memory-query}.
7015
67b5c0c1
MM
7016@kindex set record btrace
7017The @code{btrace} record target does not trace data. As a
7018convenience, when replaying, @value{GDBN} reads read-only memory off
7019the live program directly, assuming that the addresses of the
7020read-only areas don't change. This for example makes it possible to
7021disassemble code while replaying, but not to print variables.
7022In some cases, being able to inspect variables might be useful.
7023You can use the following command for that:
7024
7025@item set record btrace replay-memory-access
7026Control the behavior of the @code{btrace} recording method when
7027accessing memory during replay. If @code{read-only} (the default),
7028@value{GDBN} will only allow accesses to read-only memory.
7029If @code{read-write}, @value{GDBN} will allow accesses to read-only
7030and to read-write memory. Beware that the accessed memory corresponds
7031to the live target and not necessarily to the current replay
7032position.
7033
4a4495d6
MM
7034@item set record btrace cpu @var{identifier}
7035Set the processor to be used for enabling workarounds for processor
7036errata when decoding the trace.
7037
7038Processor errata are defects in processor operation, caused by its
7039design or manufacture. They can cause a trace not to match the
7040specification. This, in turn, may cause trace decode to fail.
7041@value{GDBN} can detect erroneous trace packets and correct them, thus
7042avoiding the decoding failures. These corrections are known as
7043@dfn{errata workarounds}, and are enabled based on the processor on
7044which the trace was recorded.
7045
7046By default, @value{GDBN} attempts to detect the processor
7047automatically, and apply the necessary workarounds for it. However,
7048you may need to specify the processor if @value{GDBN} does not yet
7049support it. This command allows you to do that, and also allows to
7050disable the workarounds.
7051
7052The argument @var{identifier} identifies the @sc{cpu} and is of the
7053form: @code{@var{vendor}:@var{procesor identifier}}. In addition,
7054there are two special identifiers, @code{none} and @code{auto}
7055(default).
7056
7057The following vendor identifiers and corresponding processor
7058identifiers are currently supported:
7059
7060@multitable @columnfractions .1 .9
7061
7062@item @code{intel}
7063@tab @var{family}/@var{model}[/@var{stepping}]
7064
7065@end multitable
7066
7067On GNU/Linux systems, the processor @var{family}, @var{model}, and
7068@var{stepping} can be obtained from @code{/proc/cpuinfo}.
7069
7070If @var{identifier} is @code{auto}, enable errata workarounds for the
7071processor on which the trace was recorded. If @var{identifier} is
7072@code{none}, errata workarounds are disabled.
7073
7074For example, when using an old @value{GDBN} on a new system, decode
7075may fail because @value{GDBN} does not support the new processor. It
7076often suffices to specify an older processor that @value{GDBN}
7077supports.
7078
7079@smallexample
7080(gdb) info record
7081Active record target: record-btrace
7082Recording format: Intel Processor Trace.
7083Buffer size: 16kB.
7084Failed to configure the Intel Processor Trace decoder: unknown cpu.
7085(gdb) set record btrace cpu intel:6/158
7086(gdb) info record
7087Active record target: record-btrace
7088Recording format: Intel Processor Trace.
7089Buffer size: 16kB.
7090Recorded 84872 instructions in 3189 functions (0 gaps) for thread 1 (...).
7091@end smallexample
7092
67b5c0c1
MM
7093@kindex show record btrace
7094@item show record btrace replay-memory-access
7095Show the current setting of @code{replay-memory-access}.
7096
4a4495d6
MM
7097@item show record btrace cpu
7098Show the processor to be used for enabling trace decode errata
7099workarounds.
7100
d33501a5
MM
7101@kindex set record btrace bts
7102@item set record btrace bts buffer-size @var{size}
7103@itemx set record btrace bts buffer-size unlimited
7104Set the requested ring buffer size for branch tracing in @acronym{BTS}
7105format. Default is 64KB.
7106
7107If @var{size} is a positive number, then @value{GDBN} will try to
7108allocate a buffer of at least @var{size} bytes for each new thread
7109that uses the btrace recording method and the @acronym{BTS} format.
7110The actually obtained buffer size may differ from the requested
7111@var{size}. Use the @code{info record} command to see the actual
7112buffer size for each thread that uses the btrace recording method and
7113the @acronym{BTS} format.
7114
7115If @var{limit} is @code{unlimited} or zero, @value{GDBN} will try to
7116allocate a buffer of 4MB.
7117
7118Bigger buffers mean longer traces. On the other hand, @value{GDBN} will
7119also need longer to process the branch trace data before it can be used.
7120
7121@item show record btrace bts buffer-size @var{size}
7122Show the current setting of the requested ring buffer size for branch
7123tracing in @acronym{BTS} format.
7124
b20a6524
MM
7125@kindex set record btrace pt
7126@item set record btrace pt buffer-size @var{size}
7127@itemx set record btrace pt buffer-size unlimited
bc504a31 7128Set the requested ring buffer size for branch tracing in Intel
b20a6524
MM
7129Processor Trace format. Default is 16KB.
7130
7131If @var{size} is a positive number, then @value{GDBN} will try to
7132allocate a buffer of at least @var{size} bytes for each new thread
bc504a31 7133that uses the btrace recording method and the Intel Processor Trace
b20a6524
MM
7134format. The actually obtained buffer size may differ from the
7135requested @var{size}. Use the @code{info record} command to see the
7136actual buffer size for each thread.
7137
7138If @var{limit} is @code{unlimited} or zero, @value{GDBN} will try to
7139allocate a buffer of 4MB.
7140
7141Bigger buffers mean longer traces. On the other hand, @value{GDBN} will
7142also need longer to process the branch trace data before it can be used.
7143
7144@item show record btrace pt buffer-size @var{size}
7145Show the current setting of the requested ring buffer size for branch
bc504a31 7146tracing in Intel Processor Trace format.
b20a6524 7147
29153c24
MS
7148@kindex info record
7149@item info record
59ea5688
MM
7150Show various statistics about the recording depending on the recording
7151method:
7152
7153@table @code
7154@item full
7155For the @code{full} recording method, it shows the state of process
7156record and its in-memory execution log buffer, including:
29153c24
MS
7157
7158@itemize @bullet
7159@item
7160Whether in record mode or replay mode.
7161@item
7162Lowest recorded instruction number (counting from when the current execution log started recording instructions).
7163@item
7164Highest recorded instruction number.
7165@item
7166Current instruction about to be replayed (if in replay mode).
7167@item
7168Number of instructions contained in the execution log.
7169@item
7170Maximum number of instructions that may be contained in the execution log.
7171@end itemize
53cc454a 7172
59ea5688 7173@item btrace
d33501a5
MM
7174For the @code{btrace} recording method, it shows:
7175
7176@itemize @bullet
7177@item
7178Recording format.
7179@item
7180Number of instructions that have been recorded.
7181@item
7182Number of blocks of sequential control-flow formed by the recorded
7183instructions.
7184@item
7185Whether in record mode or replay mode.
7186@end itemize
7187
7188For the @code{bts} recording format, it also shows:
7189@itemize @bullet
7190@item
7191Size of the perf ring buffer.
7192@end itemize
b20a6524
MM
7193
7194For the @code{pt} recording format, it also shows:
7195@itemize @bullet
7196@item
7197Size of the perf ring buffer.
7198@end itemize
59ea5688
MM
7199@end table
7200
53cc454a
HZ
7201@kindex record delete
7202@kindex rec del
7203@item record delete
a2311334 7204When record target runs in replay mode (``in the past''), delete the
53cc454a 7205subsequent execution log and begin to record a new execution log starting
a2311334 7206from the current address. This means you will abandon the previously
53cc454a 7207recorded ``future'' and begin recording a new ``future''.
59ea5688
MM
7208
7209@kindex record instruction-history
7210@kindex rec instruction-history
7211@item record instruction-history
7212Disassembles instructions from the recorded execution log. By
7213default, ten instructions are disassembled. This can be changed using
7214the @code{set record instruction-history-size} command. Instructions
da8c46d2
MM
7215are printed in execution order.
7216
0c532a29
MM
7217It can also print mixed source+disassembly if you specify the the
7218@code{/m} or @code{/s} modifier, and print the raw instructions in hex
7219as well as in symbolic form by specifying the @code{/r} modifier.
7220
7221The current position marker is printed for the instruction at the
7222current program counter value. This instruction can appear multiple
7223times in the trace and the current position marker will be printed
7224every time. To omit the current position marker, specify the
7225@code{/p} modifier.
7226
7227To better align the printed instructions when the trace contains
7228instructions from more than one function, the function name may be
7229omitted by specifying the @code{/f} modifier.
7230
da8c46d2
MM
7231Speculatively executed instructions are prefixed with @samp{?}. This
7232feature is not available for all recording formats.
7233
7234There are several ways to specify what part of the execution log to
7235disassemble:
59ea5688
MM
7236
7237@table @code
7238@item record instruction-history @var{insn}
7239Disassembles ten instructions starting from instruction number
7240@var{insn}.
7241
7242@item record instruction-history @var{insn}, +/-@var{n}
7243Disassembles @var{n} instructions around instruction number
7244@var{insn}. If @var{n} is preceded with @code{+}, disassembles
7245@var{n} instructions after instruction number @var{insn}. If
7246@var{n} is preceded with @code{-}, disassembles @var{n}
7247instructions before instruction number @var{insn}.
7248
7249@item record instruction-history
7250Disassembles ten more instructions after the last disassembly.
7251
7252@item record instruction-history -
7253Disassembles ten more instructions before the last disassembly.
7254
792005b0 7255@item record instruction-history @var{begin}, @var{end}
59ea5688
MM
7256Disassembles instructions beginning with instruction number
7257@var{begin} until instruction number @var{end}. The instruction
0688d04e 7258number @var{end} is included.
59ea5688
MM
7259@end table
7260
7261This command may not be available for all recording methods.
7262
7263@kindex set record
f81d1120
PA
7264@item set record instruction-history-size @var{size}
7265@itemx set record instruction-history-size unlimited
59ea5688
MM
7266Define how many instructions to disassemble in the @code{record
7267instruction-history} command. The default value is 10.
f81d1120 7268A @var{size} of @code{unlimited} means unlimited instructions.
59ea5688
MM
7269
7270@kindex show record
7271@item show record instruction-history-size
7272Show how many instructions to disassemble in the @code{record
7273instruction-history} command.
7274
7275@kindex record function-call-history
7276@kindex rec function-call-history
7277@item record function-call-history
7278Prints the execution history at function granularity. It prints one
7279line for each sequence of instructions that belong to the same
7280function giving the name of that function, the source lines
7281for this instruction sequence (if the @code{/l} modifier is
7282specified), and the instructions numbers that form the sequence (if
8710b709
MM
7283the @code{/i} modifier is specified). The function names are indented
7284to reflect the call stack depth if the @code{/c} modifier is
7285specified. The @code{/l}, @code{/i}, and @code{/c} modifiers can be
7286given together.
59ea5688
MM
7287
7288@smallexample
7289(@value{GDBP}) @b{list 1, 10}
72901 void foo (void)
72912 @{
72923 @}
72934
72945 void bar (void)
72956 @{
72967 ...
72978 foo ();
72989 ...
729910 @}
8710b709
MM
7300(@value{GDBP}) @b{record function-call-history /ilc}
73011 bar inst 1,4 at foo.c:6,8
73022 foo inst 5,10 at foo.c:2,3
73033 bar inst 11,13 at foo.c:9,10
59ea5688
MM
7304@end smallexample
7305
7306By default, ten lines are printed. This can be changed using the
7307@code{set record function-call-history-size} command. Functions are
7308printed in execution order. There are several ways to specify what
7309to print:
7310
7311@table @code
7312@item record function-call-history @var{func}
7313Prints ten functions starting from function number @var{func}.
7314
7315@item record function-call-history @var{func}, +/-@var{n}
7316Prints @var{n} functions around function number @var{func}. If
7317@var{n} is preceded with @code{+}, prints @var{n} functions after
7318function number @var{func}. If @var{n} is preceded with @code{-},
7319prints @var{n} functions before function number @var{func}.
7320
7321@item record function-call-history
7322Prints ten more functions after the last ten-line print.
7323
7324@item record function-call-history -
7325Prints ten more functions before the last ten-line print.
7326
792005b0 7327@item record function-call-history @var{begin}, @var{end}
59ea5688 7328Prints functions beginning with function number @var{begin} until
0688d04e 7329function number @var{end}. The function number @var{end} is included.
59ea5688
MM
7330@end table
7331
7332This command may not be available for all recording methods.
7333
f81d1120
PA
7334@item set record function-call-history-size @var{size}
7335@itemx set record function-call-history-size unlimited
59ea5688
MM
7336Define how many lines to print in the
7337@code{record function-call-history} command. The default value is 10.
f81d1120 7338A size of @code{unlimited} means unlimited lines.
59ea5688
MM
7339
7340@item show record function-call-history-size
7341Show how many lines to print in the
7342@code{record function-call-history} command.
53cc454a
HZ
7343@end table
7344
7345
6d2ebf8b 7346@node Stack
c906108c
SS
7347@chapter Examining the Stack
7348
7349When your program has stopped, the first thing you need to know is where it
7350stopped and how it got there.
7351
7352@cindex call stack
5d161b24
DB
7353Each time your program performs a function call, information about the call
7354is generated.
7355That information includes the location of the call in your program,
7356the arguments of the call,
c906108c 7357and the local variables of the function being called.
5d161b24 7358The information is saved in a block of data called a @dfn{stack frame}.
c906108c
SS
7359The stack frames are allocated in a region of memory called the @dfn{call
7360stack}.
7361
7362When your program stops, the @value{GDBN} commands for examining the
7363stack allow you to see all of this information.
7364
7365@cindex selected frame
7366One of the stack frames is @dfn{selected} by @value{GDBN} and many
7367@value{GDBN} commands refer implicitly to the selected frame. In
7368particular, whenever you ask @value{GDBN} for the value of a variable in
7369your program, the value is found in the selected frame. There are
7370special @value{GDBN} commands to select whichever frame you are
79a6e687 7371interested in. @xref{Selection, ,Selecting a Frame}.
c906108c
SS
7372
7373When your program stops, @value{GDBN} automatically selects the
5d161b24 7374currently executing frame and describes it briefly, similar to the
79a6e687 7375@code{frame} command (@pxref{Frame Info, ,Information about a Frame}).
c906108c
SS
7376
7377@menu
7378* Frames:: Stack frames
7379* Backtrace:: Backtraces
7380* Selection:: Selecting a frame
7381* Frame Info:: Information on a frame
0a232300 7382* Frame Apply:: Applying a command to several frames
0f59c28f 7383* Frame Filter Management:: Managing frame filters
c906108c
SS
7384
7385@end menu
7386
6d2ebf8b 7387@node Frames
79a6e687 7388@section Stack Frames
c906108c 7389
d4f3574e 7390@cindex frame, definition
c906108c
SS
7391@cindex stack frame
7392The call stack is divided up into contiguous pieces called @dfn{stack
7393frames}, or @dfn{frames} for short; each frame is the data associated
7394with one call to one function. The frame contains the arguments given
7395to the function, the function's local variables, and the address at
7396which the function is executing.
7397
7398@cindex initial frame
7399@cindex outermost frame
7400@cindex innermost frame
7401When your program is started, the stack has only one frame, that of the
7402function @code{main}. This is called the @dfn{initial} frame or the
7403@dfn{outermost} frame. Each time a function is called, a new frame is
7404made. Each time a function returns, the frame for that function invocation
7405is eliminated. If a function is recursive, there can be many frames for
7406the same function. The frame for the function in which execution is
7407actually occurring is called the @dfn{innermost} frame. This is the most
7408recently created of all the stack frames that still exist.
7409
7410@cindex frame pointer
7411Inside your program, stack frames are identified by their addresses. A
7412stack frame consists of many bytes, each of which has its own address; each
7413kind of computer has a convention for choosing one byte whose
7414address serves as the address of the frame. Usually this address is kept
e09f16f9
EZ
7415in a register called the @dfn{frame pointer register}
7416(@pxref{Registers, $fp}) while execution is going on in that frame.
c906108c 7417
f67ffa6a 7418@cindex frame level
c906108c 7419@cindex frame number
f67ffa6a
AB
7420@value{GDBN} labels each existing stack frame with a @dfn{level}, a
7421number that is zero for the innermost frame, one for the frame that
7422called it, and so on upward. These level numbers give you a way of
7423designating stack frames in @value{GDBN} commands. The terms
7424@dfn{frame number} and @dfn{frame level} can be used interchangeably to
7425describe this number.
c906108c 7426
6d2ebf8b
SS
7427@c The -fomit-frame-pointer below perennially causes hbox overflow
7428@c underflow problems.
c906108c
SS
7429@cindex frameless execution
7430Some compilers provide a way to compile functions so that they operate
e22ea452 7431without stack frames. (For example, the @value{NGCC} option
474c8240 7432@smallexample
6d2ebf8b 7433@samp{-fomit-frame-pointer}
474c8240 7434@end smallexample
6d2ebf8b 7435generates functions without a frame.)
c906108c
SS
7436This is occasionally done with heavily used library functions to save
7437the frame setup time. @value{GDBN} has limited facilities for dealing
7438with these function invocations. If the innermost function invocation
7439has no stack frame, @value{GDBN} nevertheless regards it as though
7440it had a separate frame, which is numbered zero as usual, allowing
7441correct tracing of the function call chain. However, @value{GDBN} has
7442no provision for frameless functions elsewhere in the stack.
7443
6d2ebf8b 7444@node Backtrace
c906108c
SS
7445@section Backtraces
7446
09d4efe1
EZ
7447@cindex traceback
7448@cindex call stack traces
c906108c
SS
7449A backtrace is a summary of how your program got where it is. It shows one
7450line per frame, for many frames, starting with the currently executing
7451frame (frame zero), followed by its caller (frame one), and on up the
7452stack.
7453
1e611234 7454@anchor{backtrace-command}
c906108c 7455@kindex backtrace
41afff9a 7456@kindex bt @r{(@code{backtrace})}
ea3b0687
TT
7457To print a backtrace of the entire stack, use the @code{backtrace}
7458command, or its alias @code{bt}. This command will print one line per
7459frame for frames in the stack. By default, all stack frames are
7460printed. You can stop the backtrace at any time by typing the system
7461interrupt character, normally @kbd{Ctrl-c}.
7462
7463@table @code
7464@item backtrace [@var{args}@dots{}]
7465@itemx bt [@var{args}@dots{}]
7466Print the backtrace of the entire stack. The optional @var{args} can
7467be one of the following:
7468
7469@table @code
7470@item @var{n}
7471@itemx @var{n}
7472Print only the innermost @var{n} frames, where @var{n} is a positive
7473number.
7474
7475@item -@var{n}
7476@itemx -@var{n}
7477Print only the outermost @var{n} frames, where @var{n} is a positive
7478number.
7479
7480@item full
7481Print the values of the local variables also. This can be combined
7482with a number to limit the number of frames shown.
7483
7484@item no-filters
1e611234
PM
7485Do not run Python frame filters on this backtrace. @xref{Frame
7486Filter API}, for more information. Additionally use @ref{disable
7487frame-filter all} to turn off all frame filters. This is only
7488relevant when @value{GDBN} has been configured with @code{Python}
7489support.
978d6c75
TT
7490
7491@item hide
7492A Python frame filter might decide to ``elide'' some frames. Normally
7493such elided frames are still printed, but they are indented relative
7494to the filtered frames that cause them to be elided. The @code{hide}
7495option causes elided frames to not be printed at all.
c906108c 7496@end table
ea3b0687 7497@end table
c906108c
SS
7498
7499@kindex where
7500@kindex info stack
c906108c
SS
7501The names @code{where} and @code{info stack} (abbreviated @code{info s})
7502are additional aliases for @code{backtrace}.
7503
839c27b7
EZ
7504@cindex multiple threads, backtrace
7505In a multi-threaded program, @value{GDBN} by default shows the
7506backtrace only for the current thread. To display the backtrace for
7507several or all of the threads, use the command @code{thread apply}
7508(@pxref{Threads, thread apply}). For example, if you type @kbd{thread
7509apply all backtrace}, @value{GDBN} will display the backtrace for all
7510the threads; this is handy when you debug a core dump of a
7511multi-threaded program.
7512
c906108c
SS
7513Each line in the backtrace shows the frame number and the function name.
7514The program counter value is also shown---unless you use @code{set
7515print address off}. The backtrace also shows the source file name and
7516line number, as well as the arguments to the function. The program
7517counter value is omitted if it is at the beginning of the code for that
7518line number.
7519
7520Here is an example of a backtrace. It was made with the command
7521@samp{bt 3}, so it shows the innermost three frames.
7522
7523@smallexample
7524@group
5d161b24 7525#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
c906108c 7526 at builtin.c:993
4f5376b2 7527#1 0x6e38 in expand_macro (sym=0x2b600, data=...) at macro.c:242
c906108c
SS
7528#2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08)
7529 at macro.c:71
7530(More stack frames follow...)
7531@end group
7532@end smallexample
7533
7534@noindent
7535The display for frame zero does not begin with a program counter
7536value, indicating that your program has stopped at the beginning of the
7537code for line @code{993} of @code{builtin.c}.
7538
4f5376b2
JB
7539@noindent
7540The value of parameter @code{data} in frame 1 has been replaced by
7541@code{@dots{}}. By default, @value{GDBN} prints the value of a parameter
7542only if it is a scalar (integer, pointer, enumeration, etc). See command
7543@kbd{set print frame-arguments} in @ref{Print Settings} for more details
7544on how to configure the way function parameter values are printed.
7545
585fdaa1 7546@cindex optimized out, in backtrace
18999be5
EZ
7547@cindex function call arguments, optimized out
7548If your program was compiled with optimizations, some compilers will
7549optimize away arguments passed to functions if those arguments are
7550never used after the call. Such optimizations generate code that
7551passes arguments through registers, but doesn't store those arguments
7552in the stack frame. @value{GDBN} has no way of displaying such
7553arguments in stack frames other than the innermost one. Here's what
7554such a backtrace might look like:
7555
7556@smallexample
7557@group
7558#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
7559 at builtin.c:993
585fdaa1
PA
7560#1 0x6e38 in expand_macro (sym=<optimized out>) at macro.c:242
7561#2 0x6840 in expand_token (obs=0x0, t=<optimized out>, td=0xf7fffb08)
18999be5
EZ
7562 at macro.c:71
7563(More stack frames follow...)
7564@end group
7565@end smallexample
7566
7567@noindent
7568The values of arguments that were not saved in their stack frames are
585fdaa1 7569shown as @samp{<optimized out>}.
18999be5
EZ
7570
7571If you need to display the values of such optimized-out arguments,
7572either deduce that from other variables whose values depend on the one
7573you are interested in, or recompile without optimizations.
7574
a8f24a35
EZ
7575@cindex backtrace beyond @code{main} function
7576@cindex program entry point
7577@cindex startup code, and backtrace
25d29d70
AC
7578Most programs have a standard user entry point---a place where system
7579libraries and startup code transition into user code. For C this is
d416eeec
EZ
7580@code{main}@footnote{
7581Note that embedded programs (the so-called ``free-standing''
7582environment) are not required to have a @code{main} function as the
7583entry point. They could even have multiple entry points.}.
7584When @value{GDBN} finds the entry function in a backtrace
25d29d70
AC
7585it will terminate the backtrace, to avoid tracing into highly
7586system-specific (and generally uninteresting) code.
7587
7588If you need to examine the startup code, or limit the number of levels
7589in a backtrace, you can change this behavior:
95f90d25
DJ
7590
7591@table @code
25d29d70
AC
7592@item set backtrace past-main
7593@itemx set backtrace past-main on
4644b6e3 7594@kindex set backtrace
25d29d70
AC
7595Backtraces will continue past the user entry point.
7596
7597@item set backtrace past-main off
95f90d25
DJ
7598Backtraces will stop when they encounter the user entry point. This is the
7599default.
7600
25d29d70 7601@item show backtrace past-main
4644b6e3 7602@kindex show backtrace
25d29d70
AC
7603Display the current user entry point backtrace policy.
7604
2315ffec
RC
7605@item set backtrace past-entry
7606@itemx set backtrace past-entry on
a8f24a35 7607Backtraces will continue past the internal entry point of an application.
2315ffec
RC
7608This entry point is encoded by the linker when the application is built,
7609and is likely before the user entry point @code{main} (or equivalent) is called.
7610
7611@item set backtrace past-entry off
d3e8051b 7612Backtraces will stop when they encounter the internal entry point of an
2315ffec
RC
7613application. This is the default.
7614
7615@item show backtrace past-entry
7616Display the current internal entry point backtrace policy.
7617
25d29d70
AC
7618@item set backtrace limit @var{n}
7619@itemx set backtrace limit 0
f81d1120 7620@itemx set backtrace limit unlimited
25d29d70 7621@cindex backtrace limit
f81d1120
PA
7622Limit the backtrace to @var{n} levels. A value of @code{unlimited}
7623or zero means unlimited levels.
95f90d25 7624
25d29d70
AC
7625@item show backtrace limit
7626Display the current limit on backtrace levels.
95f90d25
DJ
7627@end table
7628
1b56eb55
JK
7629You can control how file names are displayed.
7630
7631@table @code
7632@item set filename-display
7633@itemx set filename-display relative
7634@cindex filename-display
7635Display file names relative to the compilation directory. This is the default.
7636
7637@item set filename-display basename
7638Display only basename of a filename.
7639
7640@item set filename-display absolute
7641Display an absolute filename.
7642
7643@item show filename-display
7644Show the current way to display filenames.
7645@end table
7646
6d2ebf8b 7647@node Selection
79a6e687 7648@section Selecting a Frame
c906108c
SS
7649
7650Most commands for examining the stack and other data in your program work on
7651whichever stack frame is selected at the moment. Here are the commands for
7652selecting a stack frame; all of them finish by printing a brief description
7653of the stack frame just selected.
7654
7655@table @code
d4f3574e 7656@kindex frame@r{, selecting}
41afff9a 7657@kindex f @r{(@code{frame})}
f67ffa6a
AB
7658@item frame @r{[} @var{frame-selection-spec} @r{]}
7659@item f @r{[} @var{frame-selection-spec} @r{]}
7660The @command{frame} command allows different stack frames to be
7661selected. The @var{frame-selection-spec} can be any of the following:
7662
7663@table @code
7664@kindex frame level
7665@item @var{num}
7666@item level @var{num}
7667Select frame level @var{num}. Recall that frame zero is the innermost
c906108c 7668(currently executing) frame, frame one is the frame that called the
f67ffa6a
AB
7669innermost one, and so on. The highest level frame is usually the one
7670for @code{main}.
7671
7672As this is the most common method of navigating the frame stack, the
7673string @command{level} can be omitted. For example, the following two
7674commands are equivalent:
7675
7676@smallexample
7677(@value{GDBP}) frame 3
7678(@value{GDBP}) frame level 3
7679@end smallexample
7680
7681@kindex frame address
7682@item address @var{stack-address}
7683Select the frame with stack address @var{stack-address}. The
7684@var{stack-address} for a frame can be seen in the output of
7685@command{info frame}, for example:
7686
7687@smallexample
7688(gdb) info frame
7689Stack level 1, frame at 0x7fffffffda30:
7690 rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
7691 tail call frame, caller of frame at 0x7fffffffda30
7692 source language c++.
7693 Arglist at unknown address.
7694 Locals at unknown address, Previous frame's sp is 0x7fffffffda30
7695@end smallexample
7696
7697The @var{stack-address} for this frame is @code{0x7fffffffda30} as
7698indicated by the line:
7699
7700@smallexample
7701Stack level 1, frame at 0x7fffffffda30:
7702@end smallexample
7703
7704@kindex frame function
7705@item function @var{function-name}
7706Select the stack frame for function @var{function-name}. If there are
7707multiple stack frames for function @var{function-name} then the inner
7708most stack frame is selected.
7709
7710@kindex frame view
7711@item view @var{stack-address} @r{[} @var{pc-addr} @r{]}
7712View a frame that is not part of @value{GDBN}'s backtrace. The frame
7713viewed has stack address @var{stack-addr}, and optionally, a program
7714counter address of @var{pc-addr}.
7715
7716This is useful mainly if the chaining of stack frames has been
7717damaged by a bug, making it impossible for @value{GDBN} to assign
7718numbers properly to all frames. In addition, this can be useful
7719when your program has multiple stacks and switches between them.
7720
7721When viewing a frame outside the current backtrace using
7722@command{frame view} then you can always return to the original
7723stack using one of the previous stack frame selection instructions,
7724for example @command{frame level 0}.
7725
7726@end table
c906108c
SS
7727
7728@kindex up
7729@item up @var{n}
697aa1b7
EZ
7730Move @var{n} frames up the stack; @var{n} defaults to 1. For positive
7731numbers @var{n}, this advances toward the outermost frame, to higher
7732frame numbers, to frames that have existed longer.
c906108c
SS
7733
7734@kindex down
41afff9a 7735@kindex do @r{(@code{down})}
c906108c 7736@item down @var{n}
697aa1b7
EZ
7737Move @var{n} frames down the stack; @var{n} defaults to 1. For
7738positive numbers @var{n}, this advances toward the innermost frame, to
7739lower frame numbers, to frames that were created more recently.
7740You may abbreviate @code{down} as @code{do}.
c906108c
SS
7741@end table
7742
7743All of these commands end by printing two lines of output describing the
7744frame. The first line shows the frame number, the function name, the
7745arguments, and the source file and line number of execution in that
5d161b24 7746frame. The second line shows the text of that source line.
c906108c
SS
7747
7748@need 1000
7749For example:
7750
7751@smallexample
7752@group
7753(@value{GDBP}) up
7754#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
7755 at env.c:10
775610 read_input_file (argv[i]);
7757@end group
7758@end smallexample
7759
7760After such a printout, the @code{list} command with no arguments
7761prints ten lines centered on the point of execution in the frame.
87885426
FN
7762You can also edit the program at the point of execution with your favorite
7763editing program by typing @code{edit}.
79a6e687 7764@xref{List, ,Printing Source Lines},
87885426 7765for details.
c906108c
SS
7766
7767@table @code
fc58fa65 7768@kindex select-frame
f67ffa6a 7769@item select-frame @r{[} @var{frame-selection-spec} @r{]}
fc58fa65
AB
7770The @code{select-frame} command is a variant of @code{frame} that does
7771not display the new frame after selecting it. This command is
7772intended primarily for use in @value{GDBN} command scripts, where the
f67ffa6a
AB
7773output might be unnecessary and distracting. The
7774@var{frame-selection-spec} is as for the @command{frame} command
7775described in @ref{Selection, ,Selecting a Frame}.
fc58fa65 7776
c906108c
SS
7777@kindex down-silently
7778@kindex up-silently
7779@item up-silently @var{n}
7780@itemx down-silently @var{n}
7781These two commands are variants of @code{up} and @code{down},
7782respectively; they differ in that they do their work silently, without
7783causing display of the new frame. They are intended primarily for use
7784in @value{GDBN} command scripts, where the output might be unnecessary and
7785distracting.
7786@end table
7787
6d2ebf8b 7788@node Frame Info
79a6e687 7789@section Information About a Frame
c906108c
SS
7790
7791There are several other commands to print information about the selected
7792stack frame.
7793
7794@table @code
7795@item frame
7796@itemx f
7797When used without any argument, this command does not change which
7798frame is selected, but prints a brief description of the currently
7799selected stack frame. It can be abbreviated @code{f}. With an
7800argument, this command is used to select a stack frame.
79a6e687 7801@xref{Selection, ,Selecting a Frame}.
c906108c
SS
7802
7803@kindex info frame
41afff9a 7804@kindex info f @r{(@code{info frame})}
c906108c
SS
7805@item info frame
7806@itemx info f
7807This command prints a verbose description of the selected stack frame,
7808including:
7809
7810@itemize @bullet
5d161b24
DB
7811@item
7812the address of the frame
c906108c
SS
7813@item
7814the address of the next frame down (called by this frame)
7815@item
7816the address of the next frame up (caller of this frame)
7817@item
7818the language in which the source code corresponding to this frame is written
7819@item
7820the address of the frame's arguments
7821@item
d4f3574e
SS
7822the address of the frame's local variables
7823@item
c906108c
SS
7824the program counter saved in it (the address of execution in the caller frame)
7825@item
7826which registers were saved in the frame
7827@end itemize
7828
7829@noindent The verbose description is useful when
7830something has gone wrong that has made the stack format fail to fit
7831the usual conventions.
7832
f67ffa6a
AB
7833@item info frame @r{[} @var{frame-selection-spec} @r{]}
7834@itemx info f @r{[} @var{frame-selection-spec} @r{]}
7835Print a verbose description of the frame selected by
7836@var{frame-selection-spec}. The @var{frame-selection-spec} is the
7837same as for the @command{frame} command (@pxref{Selection, ,Selecting
7838a Frame}). The selected frame remains unchanged by this command.
c906108c
SS
7839
7840@kindex info args
d321477b 7841@item info args [-q]
c906108c
SS
7842Print the arguments of the selected frame, each on a separate line.
7843
d321477b
PW
7844The optional flag @samp{-q}, which stands for @samp{quiet}, disables
7845printing header information and messages explaining why no argument
7846have been printed.
7847
7848@item info args [-q] [-t @var{type_regexp}] [@var{regexp}]
7849Like @kbd{info args}, but only print the arguments selected
7850with the provided regexp(s).
7851
7852If @var{regexp} is provided, print only the arguments whose names
7853match the regular expression @var{regexp}.
7854
7855If @var{type_regexp} is provided, print only the arguments whose
7856types, as printed by the @code{whatis} command, match
7857the regular expression @var{type_regexp}.
7858If @var{type_regexp} contains space(s), it should be enclosed in
7859quote characters. If needed, use backslash to escape the meaning
7860of special characters or quotes.
7861
7862If both @var{regexp} and @var{type_regexp} are provided, an argument
7863is printed only if its name matches @var{regexp} and its type matches
7864@var{type_regexp}.
7865
7866@item info locals [-q]
c906108c
SS
7867@kindex info locals
7868Print the local variables of the selected frame, each on a separate
7869line. These are all variables (declared either static or automatic)
7870accessible at the point of execution of the selected frame.
7871
d321477b
PW
7872The optional flag @samp{-q}, which stands for @samp{quiet}, disables
7873printing header information and messages explaining why no local variables
7874have been printed.
7875
7876@item info locals [-q] [-t @var{type_regexp}] [@var{regexp}]
7877Like @kbd{info locals}, but only print the local variables selected
7878with the provided regexp(s).
7879
7880If @var{regexp} is provided, print only the local variables whose names
7881match the regular expression @var{regexp}.
7882
7883If @var{type_regexp} is provided, print only the local variables whose
7884types, as printed by the @code{whatis} command, match
7885the regular expression @var{type_regexp}.
7886If @var{type_regexp} contains space(s), it should be enclosed in
7887quote characters. If needed, use backslash to escape the meaning
7888of special characters or quotes.
7889
7890If both @var{regexp} and @var{type_regexp} are provided, a local variable
7891is printed only if its name matches @var{regexp} and its type matches
7892@var{type_regexp}.
7893
7894The command @kbd{info locals -q -t @var{type_regexp}} can usefully be
7895combined with the commands @kbd{frame apply} and @kbd{thread apply}.
7896For example, your program might use Resource Acquisition Is
7897Initialization types (RAII) such as @code{lock_something_t}: each
7898local variable of type @code{lock_something_t} automatically places a
7899lock that is destroyed when the variable goes out of scope. You can
7900then list all acquired locks in your program by doing
7901@smallexample
7902thread apply all -s frame apply all -s info locals -q -t lock_something_t
7903@end smallexample
7904@noindent
7905or the equivalent shorter form
7906@smallexample
7907tfaas i lo -q -t lock_something_t
7908@end smallexample
7909
c906108c
SS
7910@end table
7911
0a232300
PW
7912@node Frame Apply
7913@section Applying a Command to Several Frames.
7914@kindex frame apply
7915@cindex apply command to several frames
7916@table @code
7917@item frame apply [all | @var{count} | @var{-count} | level @var{level}@dots{}] [@var{flag}]@dots{} @var{command}
7918The @code{frame apply} command allows you to apply the named
7919@var{command} to one or more frames.
7920
7921@table @code
7922@item @code{all}
7923Specify @code{all} to apply @var{command} to all frames.
7924
7925@item @var{count}
7926Use @var{count} to apply @var{command} to the innermost @var{count}
7927frames, where @var{count} is a positive number.
7928
7929@item @var{-count}
7930Use @var{-count} to apply @var{command} to the outermost @var{count}
7931frames, where @var{count} is a positive number.
7932
7933@item @code{level}
7934Use @code{level} to apply @var{command} to the set of frames identified
7935by the @var{level} list. @var{level} is a frame level or a range of frame
7936levels as @var{level1}-@var{level2}. The frame level is the number shown
7937in the first field of the @samp{backtrace} command output.
7938E.g., @samp{2-4 6-8 3} indicates to apply @var{command} for the frames
7939at levels 2, 3, 4, 6, 7, 8, and then again on frame at level 3.
7940
7941@end table
7942
7943@end table
7944
7945Note that the frames on which @code{frame apply} applies a command are
7946also influenced by the @code{set backtrace} settings such as @code{set
7947backtrace past-main} and @code{set backtrace limit N}. See
7948@xref{Backtrace,,Backtraces}.
7949
7950The @var{flag} arguments control what output to produce and how to handle
7951errors raised when applying @var{command} to a frame. @var{flag}
7952must start with a @code{-} directly followed by one letter in
7953@code{qcs}. If several flags are provided, they must be given
7954individually, such as @code{-c -q}.
7955
7956By default, @value{GDBN} displays some frame information before the
7957output produced by @var{command}, and an error raised during the
7958execution of a @var{command} will abort @code{frame apply}. The
7959following flags can be used to fine-tune this behavior:
7960
7961@table @code
7962@item -c
7963The flag @code{-c}, which stands for @samp{continue}, causes any
7964errors in @var{command} to be displayed, and the execution of
7965@code{frame apply} then continues.
7966@item -s
7967The flag @code{-s}, which stands for @samp{silent}, causes any errors
7968or empty output produced by a @var{command} to be silently ignored.
7969That is, the execution continues, but the frame information and errors
7970are not printed.
7971@item -q
7972The flag @code{-q} (@samp{quiet}) disables printing the frame
7973information.
7974@end table
7975
7976The following example shows how the flags @code{-c} and @code{-s} are
7977working when applying the command @code{p j} to all frames, where
7978variable @code{j} can only be successfully printed in the outermost
7979@code{#1 main} frame.
7980
7981@smallexample
7982@group
7983(gdb) frame apply all p j
7984#0 some_function (i=5) at fun.c:4
7985No symbol "j" in current context.
7986(gdb) frame apply all -c p j
7987#0 some_function (i=5) at fun.c:4
7988No symbol "j" in current context.
7989#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
7990$1 = 5
7991(gdb) frame apply all -s p j
7992#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
7993$2 = 5
7994(gdb)
7995@end group
7996@end smallexample
7997
7998By default, @samp{frame apply}, prints the frame location
7999information before the command output:
8000
8001@smallexample
8002@group
8003(gdb) frame apply all p $sp
8004#0 some_function (i=5) at fun.c:4
8005$4 = (void *) 0xffffd1e0
8006#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
8007$5 = (void *) 0xffffd1f0
8008(gdb)
8009@end group
8010@end smallexample
8011
8012If flag @code{-q} is given, no frame information is printed:
8013@smallexample
8014@group
8015(gdb) frame apply all -q p $sp
8016$12 = (void *) 0xffffd1e0
8017$13 = (void *) 0xffffd1f0
8018(gdb)
8019@end group
8020@end smallexample
8021
8022@table @code
8023
8024@kindex faas
8025@cindex apply a command to all frames (ignoring errors and empty output)
8026@item faas @var{command}
8027Shortcut for @code{frame apply all -s @var{command}}.
8028Applies @var{command} on all frames, ignoring errors and empty output.
8029
8030It can for example be used to print a local variable or a function
8031argument without knowing the frame where this variable or argument
8032is, using:
8033@smallexample
8034(@value{GDBP}) faas p some_local_var_i_do_not_remember_where_it_is
8035@end smallexample
8036
8037Note that the command @code{tfaas @var{command}} applies @var{command}
8038on all frames of all threads. See @xref{Threads,,Threads}.
8039@end table
8040
8041
fc58fa65
AB
8042@node Frame Filter Management
8043@section Management of Frame Filters.
8044@cindex managing frame filters
8045
8046Frame filters are Python based utilities to manage and decorate the
8047output of frames. @xref{Frame Filter API}, for further information.
8048
8049Managing frame filters is performed by several commands available
8050within @value{GDBN}, detailed here.
8051
8052@table @code
8053@kindex info frame-filter
8054@item info frame-filter
8055Print a list of installed frame filters from all dictionaries, showing
8056their name, priority and enabled status.
8057
8058@kindex disable frame-filter
8059@anchor{disable frame-filter all}
8060@item disable frame-filter @var{filter-dictionary} @var{filter-name}
8061Disable a frame filter in the dictionary matching
8062@var{filter-dictionary} and @var{filter-name}. The
8063@var{filter-dictionary} may be @code{all}, @code{global},
8064@code{progspace}, or the name of the object file where the frame filter
8065dictionary resides. When @code{all} is specified, all frame filters
8066across all dictionaries are disabled. The @var{filter-name} is the name
8067of the frame filter and is used when @code{all} is not the option for
8068@var{filter-dictionary}. A disabled frame-filter is not deleted, it
8069may be enabled again later.
8070
8071@kindex enable frame-filter
8072@item enable frame-filter @var{filter-dictionary} @var{filter-name}
8073Enable a frame filter in the dictionary matching
8074@var{filter-dictionary} and @var{filter-name}. The
8075@var{filter-dictionary} may be @code{all}, @code{global},
8076@code{progspace} or the name of the object file where the frame filter
8077dictionary resides. When @code{all} is specified, all frame filters across
8078all dictionaries are enabled. The @var{filter-name} is the name of the frame
8079filter and is used when @code{all} is not the option for
8080@var{filter-dictionary}.
8081
8082Example:
8083
8084@smallexample
8085(gdb) info frame-filter
8086
8087global frame-filters:
8088 Priority Enabled Name
8089 1000 No PrimaryFunctionFilter
8090 100 Yes Reverse
8091
8092progspace /build/test frame-filters:
8093 Priority Enabled Name
8094 100 Yes ProgspaceFilter
8095
8096objfile /build/test frame-filters:
8097 Priority Enabled Name
8098 999 Yes BuildProgra Filter
8099
8100(gdb) disable frame-filter /build/test BuildProgramFilter
8101(gdb) info frame-filter
8102
8103global frame-filters:
8104 Priority Enabled Name
8105 1000 No PrimaryFunctionFilter
8106 100 Yes Reverse
8107
8108progspace /build/test frame-filters:
8109 Priority Enabled Name
8110 100 Yes ProgspaceFilter
8111
8112objfile /build/test frame-filters:
8113 Priority Enabled Name
8114 999 No BuildProgramFilter
8115
8116(gdb) enable frame-filter global PrimaryFunctionFilter
8117(gdb) info frame-filter
8118
8119global frame-filters:
8120 Priority Enabled Name
8121 1000 Yes PrimaryFunctionFilter
8122 100 Yes Reverse
8123
8124progspace /build/test frame-filters:
8125 Priority Enabled Name
8126 100 Yes ProgspaceFilter
8127
8128objfile /build/test frame-filters:
8129 Priority Enabled Name
8130 999 No BuildProgramFilter
8131@end smallexample
8132
8133@kindex set frame-filter priority
8134@item set frame-filter priority @var{filter-dictionary} @var{filter-name} @var{priority}
8135Set the @var{priority} of a frame filter in the dictionary matching
8136@var{filter-dictionary}, and the frame filter name matching
8137@var{filter-name}. The @var{filter-dictionary} may be @code{global},
8138@code{progspace} or the name of the object file where the frame filter
8139dictionary resides. The @var{priority} is an integer.
8140
8141@kindex show frame-filter priority
8142@item show frame-filter priority @var{filter-dictionary} @var{filter-name}
8143Show the @var{priority} of a frame filter in the dictionary matching
8144@var{filter-dictionary}, and the frame filter name matching
8145@var{filter-name}. The @var{filter-dictionary} may be @code{global},
8146@code{progspace} or the name of the object file where the frame filter
8147dictionary resides.
8148
8149Example:
8150
8151@smallexample
8152(gdb) info frame-filter
8153
8154global frame-filters:
8155 Priority Enabled Name
8156 1000 Yes PrimaryFunctionFilter
8157 100 Yes Reverse
8158
8159progspace /build/test frame-filters:
8160 Priority Enabled Name
8161 100 Yes ProgspaceFilter
8162
8163objfile /build/test frame-filters:
8164 Priority Enabled Name
8165 999 No BuildProgramFilter
8166
8167(gdb) set frame-filter priority global Reverse 50
8168(gdb) info frame-filter
8169
8170global frame-filters:
8171 Priority Enabled Name
8172 1000 Yes PrimaryFunctionFilter
8173 50 Yes Reverse
8174
8175progspace /build/test frame-filters:
8176 Priority Enabled Name
8177 100 Yes ProgspaceFilter
8178
8179objfile /build/test frame-filters:
8180 Priority Enabled Name
8181 999 No BuildProgramFilter
8182@end smallexample
8183@end table
c906108c 8184
6d2ebf8b 8185@node Source
c906108c
SS
8186@chapter Examining Source Files
8187
8188@value{GDBN} can print parts of your program's source, since the debugging
8189information recorded in the program tells @value{GDBN} what source files were
8190used to build it. When your program stops, @value{GDBN} spontaneously prints
8191the line where it stopped. Likewise, when you select a stack frame
79a6e687 8192(@pxref{Selection, ,Selecting a Frame}), @value{GDBN} prints the line where
c906108c
SS
8193execution in that frame has stopped. You can print other portions of
8194source files by explicit command.
8195
7a292a7a 8196If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may
d4f3574e 8197prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using
7a292a7a 8198@value{GDBN} under @sc{gnu} Emacs}.
c906108c
SS
8199
8200@menu
8201* List:: Printing source lines
2a25a5ba 8202* Specify Location:: How to specify code locations
87885426 8203* Edit:: Editing source files
c906108c 8204* Search:: Searching source files
c906108c
SS
8205* Source Path:: Specifying source directories
8206* Machine Code:: Source and machine code
8207@end menu
8208
6d2ebf8b 8209@node List
79a6e687 8210@section Printing Source Lines
c906108c
SS
8211
8212@kindex list
41afff9a 8213@kindex l @r{(@code{list})}
c906108c 8214To print lines from a source file, use the @code{list} command
5d161b24 8215(abbreviated @code{l}). By default, ten lines are printed.
2a25a5ba
EZ
8216There are several ways to specify what part of the file you want to
8217print; see @ref{Specify Location}, for the full list.
c906108c
SS
8218
8219Here are the forms of the @code{list} command most commonly used:
8220
8221@table @code
8222@item list @var{linenum}
8223Print lines centered around line number @var{linenum} in the
8224current source file.
8225
8226@item list @var{function}
8227Print lines centered around the beginning of function
8228@var{function}.
8229
8230@item list
8231Print more lines. If the last lines printed were printed with a
8232@code{list} command, this prints lines following the last lines
8233printed; however, if the last line printed was a solitary line printed
8234as part of displaying a stack frame (@pxref{Stack, ,Examining the
8235Stack}), this prints lines centered around that line.
8236
8237@item list -
8238Print lines just before the lines last printed.
8239@end table
8240
9c16f35a 8241@cindex @code{list}, how many lines to display
c906108c
SS
8242By default, @value{GDBN} prints ten source lines with any of these forms of
8243the @code{list} command. You can change this using @code{set listsize}:
8244
8245@table @code
8246@kindex set listsize
8247@item set listsize @var{count}
f81d1120 8248@itemx set listsize unlimited
c906108c
SS
8249Make the @code{list} command display @var{count} source lines (unless
8250the @code{list} argument explicitly specifies some other number).
f81d1120 8251Setting @var{count} to @code{unlimited} or 0 means there's no limit.
c906108c
SS
8252
8253@kindex show listsize
8254@item show listsize
8255Display the number of lines that @code{list} prints.
8256@end table
8257
8258Repeating a @code{list} command with @key{RET} discards the argument,
8259so it is equivalent to typing just @code{list}. This is more useful
8260than listing the same lines again. An exception is made for an
8261argument of @samp{-}; that argument is preserved in repetition so that
8262each repetition moves up in the source file.
8263
c906108c 8264In general, the @code{list} command expects you to supply zero, one or two
629500fa 8265@dfn{locations}. Locations specify source lines; there are several ways
2a25a5ba
EZ
8266of writing them (@pxref{Specify Location}), but the effect is always
8267to specify some source line.
8268
c906108c
SS
8269Here is a complete description of the possible arguments for @code{list}:
8270
8271@table @code
629500fa
KS
8272@item list @var{location}
8273Print lines centered around the line specified by @var{location}.
c906108c
SS
8274
8275@item list @var{first},@var{last}
8276Print lines from @var{first} to @var{last}. Both arguments are
629500fa
KS
8277locations. When a @code{list} command has two locations, and the
8278source file of the second location is omitted, this refers to
8279the same source file as the first location.
c906108c
SS
8280
8281@item list ,@var{last}
8282Print lines ending with @var{last}.
8283
8284@item list @var{first},
8285Print lines starting with @var{first}.
8286
8287@item list +
8288Print lines just after the lines last printed.
8289
8290@item list -
8291Print lines just before the lines last printed.
8292
8293@item list
8294As described in the preceding table.
8295@end table
8296
2a25a5ba
EZ
8297@node Specify Location
8298@section Specifying a Location
8299@cindex specifying location
629500fa
KS
8300@cindex location
8301@cindex source location
8302
8303@menu
8304* Linespec Locations:: Linespec locations
8305* Explicit Locations:: Explicit locations
8306* Address Locations:: Address locations
8307@end menu
c906108c 8308
2a25a5ba
EZ
8309Several @value{GDBN} commands accept arguments that specify a location
8310of your program's code. Since @value{GDBN} is a source-level
629500fa
KS
8311debugger, a location usually specifies some line in the source code.
8312Locations may be specified using three different formats:
8313linespec locations, explicit locations, or address locations.
c906108c 8314
629500fa
KS
8315@node Linespec Locations
8316@subsection Linespec Locations
8317@cindex linespec locations
8318
8319A @dfn{linespec} is a colon-separated list of source location parameters such
8320as file name, function name, etc. Here are all the different ways of
8321specifying a linespec:
c906108c 8322
2a25a5ba
EZ
8323@table @code
8324@item @var{linenum}
8325Specifies the line number @var{linenum} of the current source file.
c906108c 8326
2a25a5ba
EZ
8327@item -@var{offset}
8328@itemx +@var{offset}
8329Specifies the line @var{offset} lines before or after the @dfn{current
8330line}. For the @code{list} command, the current line is the last one
8331printed; for the breakpoint commands, this is the line at which
8332execution stopped in the currently selected @dfn{stack frame}
8333(@pxref{Frames, ,Frames}, for a description of stack frames.) When
8334used as the second of the two linespecs in a @code{list} command,
8335this specifies the line @var{offset} lines up or down from the first
8336linespec.
8337
8338@item @var{filename}:@var{linenum}
8339Specifies the line @var{linenum} in the source file @var{filename}.
4aac40c8
TT
8340If @var{filename} is a relative file name, then it will match any
8341source file name with the same trailing components. For example, if
8342@var{filename} is @samp{gcc/expr.c}, then it will match source file
8343name of @file{/build/trunk/gcc/expr.c}, but not
8344@file{/build/trunk/libcpp/expr.c} or @file{/build/trunk/gcc/x-expr.c}.
c906108c
SS
8345
8346@item @var{function}
8347Specifies the line that begins the body of the function @var{function}.
2a25a5ba 8348For example, in C, this is the line with the open brace.
c906108c 8349
a20714ff
PA
8350By default, in C@t{++} and Ada, @var{function} is interpreted as
8351specifying all functions named @var{function} in all scopes. For
8352C@t{++}, this means in all namespaces and classes. For Ada, this
8353means in all packages.
8354
8355For example, assuming a program with C@t{++} symbols named
8356@code{A::B::func} and @code{B::func}, both commands @w{@kbd{break
8357func}} and @w{@kbd{break B::func}} set a breakpoint on both symbols.
8358
8359Commands that accept a linespec let you override this with the
8360@code{-qualified} option. For example, @w{@kbd{break -qualified
8361func}} sets a breakpoint on a free-function named @code{func} ignoring
8362any C@t{++} class methods and namespace functions called @code{func}.
8363
8364@xref{Explicit Locations}.
8365
9ef07c8c
TT
8366@item @var{function}:@var{label}
8367Specifies the line where @var{label} appears in @var{function}.
8368
c906108c 8369@item @var{filename}:@var{function}
2a25a5ba
EZ
8370Specifies the line that begins the body of the function @var{function}
8371in the file @var{filename}. You only need the file name with a
8372function name to avoid ambiguity when there are identically named
8373functions in different source files.
c906108c 8374
0f5238ed 8375@item @var{label}
629500fa
KS
8376Specifies the line at which the label named @var{label} appears
8377in the function corresponding to the currently selected stack frame.
8378If there is no current selected stack frame (for instance, if the inferior
8379is not running), then @value{GDBN} will not search for a label.
8380
8381@cindex breakpoint at static probe point
8382@item -pstap|-probe-stap @r{[}@var{objfile}:@r{[}@var{provider}:@r{]}@r{]}@var{name}
8383The @sc{gnu}/Linux tool @code{SystemTap} provides a way for
8384applications to embed static probes. @xref{Static Probe Points}, for more
8385information on finding and using static probes. This form of linespec
8386specifies the location of such a static probe.
8387
8388If @var{objfile} is given, only probes coming from that shared library
8389or executable matching @var{objfile} as a regular expression are considered.
8390If @var{provider} is given, then only probes from that provider are considered.
8391If several probes match the spec, @value{GDBN} will insert a breakpoint at
8392each one of those probes.
8393@end table
8394
8395@node Explicit Locations
8396@subsection Explicit Locations
8397@cindex explicit locations
8398
8399@dfn{Explicit locations} allow the user to directly specify the source
8400location's parameters using option-value pairs.
8401
8402Explicit locations are useful when several functions, labels, or
8403file names have the same name (base name for files) in the program's
8404sources. In these cases, explicit locations point to the source
8405line you meant more accurately and unambiguously. Also, using
8406explicit locations might be faster in large programs.
8407
8408For example, the linespec @samp{foo:bar} may refer to a function @code{bar}
8409defined in the file named @file{foo} or the label @code{bar} in a function
8410named @code{foo}. @value{GDBN} must search either the file system or
8411the symbol table to know.
8412
8413The list of valid explicit location options is summarized in the
8414following table:
8415
8416@table @code
8417@item -source @var{filename}
8418The value specifies the source file name. To differentiate between
8419files with the same base name, prepend as many directories as is necessary
8420to uniquely identify the desired file, e.g., @file{foo/bar/baz.c}. Otherwise
8421@value{GDBN} will use the first file it finds with the given base
8422name. This option requires the use of either @code{-function} or @code{-line}.
8423
8424@item -function @var{function}
8425The value specifies the name of a function. Operations
8426on function locations unmodified by other options (such as @code{-label}
8427or @code{-line}) refer to the line that begins the body of the function.
8428In C, for example, this is the line with the open brace.
8429
a20714ff
PA
8430By default, in C@t{++} and Ada, @var{function} is interpreted as
8431specifying all functions named @var{function} in all scopes. For
8432C@t{++}, this means in all namespaces and classes. For Ada, this
8433means in all packages.
8434
8435For example, assuming a program with C@t{++} symbols named
8436@code{A::B::func} and @code{B::func}, both commands @w{@kbd{break
8437-function func}} and @w{@kbd{break -function B::func}} set a
8438breakpoint on both symbols.
8439
8440You can use the @kbd{-qualified} flag to override this (see below).
8441
8442@item -qualified
8443
8444This flag makes @value{GDBN} interpret a function name specified with
8445@kbd{-function} as a complete fully-qualified name.
8446
8447For example, assuming a C@t{++} program with symbols named
8448@code{A::B::func} and @code{B::func}, the @w{@kbd{break -qualified
8449-function B::func}} command sets a breakpoint on @code{B::func}, only.
8450
8451(Note: the @kbd{-qualified} option can precede a linespec as well
8452(@pxref{Linespec Locations}), so the particular example above could be
8453simplified as @w{@kbd{break -qualified B::func}}.)
8454
629500fa
KS
8455@item -label @var{label}
8456The value specifies the name of a label. When the function
8457name is not specified, the label is searched in the function of the currently
8458selected stack frame.
8459
8460@item -line @var{number}
8461The value specifies a line offset for the location. The offset may either
8462be absolute (@code{-line 3}) or relative (@code{-line +3}), depending on
8463the command. When specified without any other options, the line offset is
8464relative to the current line.
8465@end table
8466
8467Explicit location options may be abbreviated by omitting any non-unique
a20714ff 8468trailing characters from the option name, e.g., @w{@kbd{break -s main.c -li 3}}.
629500fa
KS
8469
8470@node Address Locations
8471@subsection Address Locations
8472@cindex address locations
8473
8474@dfn{Address locations} indicate a specific program address. They have
8475the generalized form *@var{address}.
8476
8477For line-oriented commands, such as @code{list} and @code{edit}, this
8478specifies a source line that contains @var{address}. For @code{break} and
8479other breakpoint-oriented commands, this can be used to set breakpoints in
2a25a5ba
EZ
8480parts of your program which do not have debugging information or
8481source files.
8482
8483Here @var{address} may be any expression valid in the current working
8484language (@pxref{Languages, working language}) that specifies a code
5fa54e5d 8485address. In addition, as a convenience, @value{GDBN} extends the
629500fa
KS
8486semantics of expressions used in locations to cover several situations
8487that frequently occur during debugging. Here are the various forms
5fa54e5d 8488of @var{address}:
2a25a5ba
EZ
8489
8490@table @code
8491@item @var{expression}
8492Any expression valid in the current working language.
8493
8494@item @var{funcaddr}
8495An address of a function or procedure derived from its name. In C,
9c37b5ae 8496C@t{++}, Objective-C, Fortran, minimal, and assembly, this is
2a25a5ba
EZ
8497simply the function's name @var{function} (and actually a special case
8498of a valid expression). In Pascal and Modula-2, this is
8499@code{&@var{function}}. In Ada, this is @code{@var{function}'Address}
8500(although the Pascal form also works).
8501
8502This form specifies the address of the function's first instruction,
8503before the stack frame and arguments have been set up.
8504
9a284c97 8505@item '@var{filename}':@var{funcaddr}
2a25a5ba
EZ
8506Like @var{funcaddr} above, but also specifies the name of the source
8507file explicitly. This is useful if the name of the function does not
8508specify the function unambiguously, e.g., if there are several
8509functions with identical names in different source files.
c906108c
SS
8510@end table
8511
87885426 8512@node Edit
79a6e687 8513@section Editing Source Files
87885426
FN
8514@cindex editing source files
8515
8516@kindex edit
8517@kindex e @r{(@code{edit})}
8518To edit the lines in a source file, use the @code{edit} command.
8519The editing program of your choice
8520is invoked with the current line set to
8521the active line in the program.
8522Alternatively, there are several ways to specify what part of the file you
2a25a5ba 8523want to print if you want to see other parts of the program:
87885426
FN
8524
8525@table @code
2a25a5ba
EZ
8526@item edit @var{location}
8527Edit the source file specified by @code{location}. Editing starts at
8528that @var{location}, e.g., at the specified source line of the
8529specified file. @xref{Specify Location}, for all the possible forms
8530of the @var{location} argument; here are the forms of the @code{edit}
8531command most commonly used:
87885426 8532
2a25a5ba 8533@table @code
87885426
FN
8534@item edit @var{number}
8535Edit the current source file with @var{number} as the active line number.
8536
8537@item edit @var{function}
8538Edit the file containing @var{function} at the beginning of its definition.
2a25a5ba 8539@end table
87885426 8540
87885426
FN
8541@end table
8542
79a6e687 8543@subsection Choosing your Editor
87885426
FN
8544You can customize @value{GDBN} to use any editor you want
8545@footnote{
8546The only restriction is that your editor (say @code{ex}), recognizes the
8547following command-line syntax:
10998722 8548@smallexample
87885426 8549ex +@var{number} file
10998722 8550@end smallexample
15387254
EZ
8551The optional numeric value +@var{number} specifies the number of the line in
8552the file where to start editing.}.
8553By default, it is @file{@value{EDITOR}}, but you can change this
10998722
AC
8554by setting the environment variable @code{EDITOR} before using
8555@value{GDBN}. For example, to configure @value{GDBN} to use the
8556@code{vi} editor, you could use these commands with the @code{sh} shell:
8557@smallexample
87885426
FN
8558EDITOR=/usr/bin/vi
8559export EDITOR
15387254 8560gdb @dots{}
10998722 8561@end smallexample
87885426 8562or in the @code{csh} shell,
10998722 8563@smallexample
87885426 8564setenv EDITOR /usr/bin/vi
15387254 8565gdb @dots{}
10998722 8566@end smallexample
87885426 8567
6d2ebf8b 8568@node Search
79a6e687 8569@section Searching Source Files
15387254 8570@cindex searching source files
c906108c
SS
8571
8572There are two commands for searching through the current source file for a
8573regular expression.
8574
8575@table @code
8576@kindex search
8577@kindex forward-search
1e96de83 8578@kindex fo @r{(@code{forward-search})}
c906108c
SS
8579@item forward-search @var{regexp}
8580@itemx search @var{regexp}
8581The command @samp{forward-search @var{regexp}} checks each line,
8582starting with the one following the last line listed, for a match for
5d161b24 8583@var{regexp}. It lists the line that is found. You can use the
c906108c
SS
8584synonym @samp{search @var{regexp}} or abbreviate the command name as
8585@code{fo}.
8586
09d4efe1 8587@kindex reverse-search
c906108c
SS
8588@item reverse-search @var{regexp}
8589The command @samp{reverse-search @var{regexp}} checks each line, starting
8590with the one before the last line listed and going backward, for a match
8591for @var{regexp}. It lists the line that is found. You can abbreviate
8592this command as @code{rev}.
8593@end table
c906108c 8594
6d2ebf8b 8595@node Source Path
79a6e687 8596@section Specifying Source Directories
c906108c
SS
8597
8598@cindex source path
8599@cindex directories for source files
8600Executable programs sometimes do not record the directories of the source
8601files from which they were compiled, just the names. Even when they do,
8602the directories could be moved between the compilation and your debugging
8603session. @value{GDBN} has a list of directories to search for source files;
8604this is called the @dfn{source path}. Each time @value{GDBN} wants a source file,
8605it tries all the directories in the list, in the order they are present
0b66e38c
EZ
8606in the list, until it finds a file with the desired name.
8607
8608For example, suppose an executable references the file
8609@file{/usr/src/foo-1.0/lib/foo.c}, and our source path is
8610@file{/mnt/cross}. The file is first looked up literally; if this
8611fails, @file{/mnt/cross/usr/src/foo-1.0/lib/foo.c} is tried; if this
8612fails, @file{/mnt/cross/foo.c} is opened; if this fails, an error
8613message is printed. @value{GDBN} does not look up the parts of the
8614source file name, such as @file{/mnt/cross/src/foo-1.0/lib/foo.c}.
8615Likewise, the subdirectories of the source path are not searched: if
8616the source path is @file{/mnt/cross}, and the binary refers to
8617@file{foo.c}, @value{GDBN} would not find it under
8618@file{/mnt/cross/usr/src/foo-1.0/lib}.
8619
8620Plain file names, relative file names with leading directories, file
8621names containing dots, etc.@: are all treated as described above; for
8622instance, if the source path is @file{/mnt/cross}, and the source file
8623is recorded as @file{../lib/foo.c}, @value{GDBN} would first try
8624@file{../lib/foo.c}, then @file{/mnt/cross/../lib/foo.c}, and after
8625that---@file{/mnt/cross/foo.c}.
8626
8627Note that the executable search path is @emph{not} used to locate the
cd852561 8628source files.
c906108c
SS
8629
8630Whenever you reset or rearrange the source path, @value{GDBN} clears out
8631any information it has cached about where source files are found and where
8632each line is in the file.
8633
8634@kindex directory
8635@kindex dir
d4f3574e
SS
8636When you start @value{GDBN}, its source path includes only @samp{cdir}
8637and @samp{cwd}, in that order.
c906108c
SS
8638To add other directories, use the @code{directory} command.
8639
4b505b12
AS
8640The search path is used to find both program source files and @value{GDBN}
8641script files (read using the @samp{-command} option and @samp{source} command).
8642
30daae6c
JB
8643In addition to the source path, @value{GDBN} provides a set of commands
8644that manage a list of source path substitution rules. A @dfn{substitution
8645rule} specifies how to rewrite source directories stored in the program's
8646debug information in case the sources were moved to a different
8647directory between compilation and debugging. A rule is made of
8648two strings, the first specifying what needs to be rewritten in
8649the path, and the second specifying how it should be rewritten.
8650In @ref{set substitute-path}, we name these two parts @var{from} and
8651@var{to} respectively. @value{GDBN} does a simple string replacement
8652of @var{from} with @var{to} at the start of the directory part of the
8653source file name, and uses that result instead of the original file
8654name to look up the sources.
8655
8656Using the previous example, suppose the @file{foo-1.0} tree has been
8657moved from @file{/usr/src} to @file{/mnt/cross}, then you can tell
3f94c067 8658@value{GDBN} to replace @file{/usr/src} in all source path names with
30daae6c
JB
8659@file{/mnt/cross}. The first lookup will then be
8660@file{/mnt/cross/foo-1.0/lib/foo.c} in place of the original location
8661of @file{/usr/src/foo-1.0/lib/foo.c}. To define a source path
8662substitution rule, use the @code{set substitute-path} command
8663(@pxref{set substitute-path}).
8664
8665To avoid unexpected substitution results, a rule is applied only if the
8666@var{from} part of the directory name ends at a directory separator.
8667For instance, a rule substituting @file{/usr/source} into
8668@file{/mnt/cross} will be applied to @file{/usr/source/foo-1.0} but
8669not to @file{/usr/sourceware/foo-2.0}. And because the substitution
d3e8051b 8670is applied only at the beginning of the directory name, this rule will
30daae6c
JB
8671not be applied to @file{/root/usr/source/baz.c} either.
8672
8673In many cases, you can achieve the same result using the @code{directory}
8674command. However, @code{set substitute-path} can be more efficient in
8675the case where the sources are organized in a complex tree with multiple
8676subdirectories. With the @code{directory} command, you need to add each
8677subdirectory of your project. If you moved the entire tree while
8678preserving its internal organization, then @code{set substitute-path}
8679allows you to direct the debugger to all the sources with one single
8680command.
8681
8682@code{set substitute-path} is also more than just a shortcut command.
8683The source path is only used if the file at the original location no
8684longer exists. On the other hand, @code{set substitute-path} modifies
8685the debugger behavior to look at the rewritten location instead. So, if
8686for any reason a source file that is not relevant to your executable is
8687located at the original location, a substitution rule is the only
3f94c067 8688method available to point @value{GDBN} at the new location.
30daae6c 8689
29b0e8a2
JM
8690@cindex @samp{--with-relocated-sources}
8691@cindex default source path substitution
8692You can configure a default source path substitution rule by
8693configuring @value{GDBN} with the
8694@samp{--with-relocated-sources=@var{dir}} option. The @var{dir}
8695should be the name of a directory under @value{GDBN}'s configured
8696prefix (set with @samp{--prefix} or @samp{--exec-prefix}), and
8697directory names in debug information under @var{dir} will be adjusted
8698automatically if the installed @value{GDBN} is moved to a new
8699location. This is useful if @value{GDBN}, libraries or executables
8700with debug information and corresponding source code are being moved
8701together.
8702
c906108c
SS
8703@table @code
8704@item directory @var{dirname} @dots{}
8705@item dir @var{dirname} @dots{}
8706Add directory @var{dirname} to the front of the source path. Several
d4f3574e
SS
8707directory names may be given to this command, separated by @samp{:}
8708(@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as
8709part of absolute file names) or
c906108c
SS
8710whitespace. You may specify a directory that is already in the source
8711path; this moves it forward, so @value{GDBN} searches it sooner.
8712
8713@kindex cdir
8714@kindex cwd
41afff9a 8715@vindex $cdir@r{, convenience variable}
d3e8051b 8716@vindex $cwd@r{, convenience variable}
c906108c
SS
8717@cindex compilation directory
8718@cindex current directory
8719@cindex working directory
8720@cindex directory, current
8721@cindex directory, compilation
8722You can use the string @samp{$cdir} to refer to the compilation
8723directory (if one is recorded), and @samp{$cwd} to refer to the current
8724working directory. @samp{$cwd} is not the same as @samp{.}---the former
8725tracks the current working directory as it changes during your @value{GDBN}
8726session, while the latter is immediately expanded to the current
8727directory at the time you add an entry to the source path.
8728
8729@item directory
cd852561 8730Reset the source path to its default value (@samp{$cdir:$cwd} on Unix systems). This requires confirmation.
c906108c
SS
8731
8732@c RET-repeat for @code{directory} is explicitly disabled, but since
8733@c repeating it would be a no-op we do not say that. (thanks to RMS)
8734
99e7ae30
DE
8735@item set directories @var{path-list}
8736@kindex set directories
8737Set the source path to @var{path-list}.
8738@samp{$cdir:$cwd} are added if missing.
8739
c906108c
SS
8740@item show directories
8741@kindex show directories
8742Print the source path: show which directories it contains.
30daae6c
JB
8743
8744@anchor{set substitute-path}
8745@item set substitute-path @var{from} @var{to}
8746@kindex set substitute-path
8747Define a source path substitution rule, and add it at the end of the
8748current list of existing substitution rules. If a rule with the same
8749@var{from} was already defined, then the old rule is also deleted.
8750
8751For example, if the file @file{/foo/bar/baz.c} was moved to
8752@file{/mnt/cross/baz.c}, then the command
8753
8754@smallexample
c58b006b 8755(@value{GDBP}) set substitute-path /foo/bar /mnt/cross
30daae6c
JB
8756@end smallexample
8757
8758@noindent
c58b006b 8759will tell @value{GDBN} to replace @samp{/foo/bar} with
30daae6c
JB
8760@samp{/mnt/cross}, which will allow @value{GDBN} to find the file
8761@file{baz.c} even though it was moved.
8762
8763In the case when more than one substitution rule have been defined,
8764the rules are evaluated one by one in the order where they have been
8765defined. The first one matching, if any, is selected to perform
8766the substitution.
8767
8768For instance, if we had entered the following commands:
8769
8770@smallexample
8771(@value{GDBP}) set substitute-path /usr/src/include /mnt/include
8772(@value{GDBP}) set substitute-path /usr/src /mnt/src
8773@end smallexample
8774
8775@noindent
8776@value{GDBN} would then rewrite @file{/usr/src/include/defs.h} into
8777@file{/mnt/include/defs.h} by using the first rule. However, it would
8778use the second rule to rewrite @file{/usr/src/lib/foo.c} into
8779@file{/mnt/src/lib/foo.c}.
8780
8781
8782@item unset substitute-path [path]
8783@kindex unset substitute-path
8784If a path is specified, search the current list of substitution rules
8785for a rule that would rewrite that path. Delete that rule if found.
8786A warning is emitted by the debugger if no rule could be found.
8787
8788If no path is specified, then all substitution rules are deleted.
8789
8790@item show substitute-path [path]
8791@kindex show substitute-path
8792If a path is specified, then print the source path substitution rule
8793which would rewrite that path, if any.
8794
8795If no path is specified, then print all existing source path substitution
8796rules.
8797
c906108c
SS
8798@end table
8799
8800If your source path is cluttered with directories that are no longer of
8801interest, @value{GDBN} may sometimes cause confusion by finding the wrong
8802versions of source. You can correct the situation as follows:
8803
8804@enumerate
8805@item
cd852561 8806Use @code{directory} with no argument to reset the source path to its default value.
c906108c
SS
8807
8808@item
8809Use @code{directory} with suitable arguments to reinstall the
8810directories you want in the source path. You can add all the
8811directories in one command.
8812@end enumerate
8813
6d2ebf8b 8814@node Machine Code
79a6e687 8815@section Source and Machine Code
15387254 8816@cindex source line and its code address
c906108c
SS
8817
8818You can use the command @code{info line} to map source lines to program
8819addresses (and vice versa), and the command @code{disassemble} to display
91440f57
HZ
8820a range of addresses as machine instructions. You can use the command
8821@code{set disassemble-next-line} to set whether to disassemble next
8822source line when execution stops. When run under @sc{gnu} Emacs
d4f3574e 8823mode, the @code{info line} command causes the arrow to point to the
5d161b24 8824line specified. Also, @code{info line} prints addresses in symbolic form as
c906108c
SS
8825well as hex.
8826
8827@table @code
8828@kindex info line
db1ae9c5
AB
8829@item info line
8830@itemx info line @var{location}
c906108c 8831Print the starting and ending addresses of the compiled code for
629500fa 8832source line @var{location}. You can specify source lines in any of
db1ae9c5
AB
8833the ways documented in @ref{Specify Location}. With no @var{location}
8834information about the current source line is printed.
c906108c
SS
8835@end table
8836
8837For example, we can use @code{info line} to discover the location of
8838the object code for the first line of function
8839@code{m4_changequote}:
8840
8841@smallexample
96a2c332 8842(@value{GDBP}) info line m4_changequote
db1ae9c5
AB
8843Line 895 of "builtin.c" starts at pc 0x634c <m4_changequote> and \
8844 ends at 0x6350 <m4_changequote+4>.
c906108c
SS
8845@end smallexample
8846
8847@noindent
15387254 8848@cindex code address and its source line
c906108c 8849We can also inquire (using @code{*@var{addr}} as the form for
629500fa 8850@var{location}) what source line covers a particular address:
c906108c
SS
8851@smallexample
8852(@value{GDBP}) info line *0x63ff
db1ae9c5
AB
8853Line 926 of "builtin.c" starts at pc 0x63e4 <m4_changequote+152> and \
8854 ends at 0x6404 <m4_changequote+184>.
c906108c
SS
8855@end smallexample
8856
8857@cindex @code{$_} and @code{info line}
15387254 8858@cindex @code{x} command, default address
41afff9a 8859@kindex x@r{(examine), and} info line
c906108c
SS
8860After @code{info line}, the default address for the @code{x} command
8861is changed to the starting address of the line, so that @samp{x/i} is
8862sufficient to begin examining the machine code (@pxref{Memory,
79a6e687 8863,Examining Memory}). Also, this address is saved as the value of the
c906108c 8864convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience
79a6e687 8865Variables}).
c906108c 8866
db1ae9c5
AB
8867@cindex info line, repeated calls
8868After @code{info line}, using @code{info line} again without
8869specifying a location will display information about the next source
8870line.
8871
c906108c
SS
8872@table @code
8873@kindex disassemble
8874@cindex assembly instructions
8875@cindex instructions, assembly
8876@cindex machine instructions
8877@cindex listing machine instructions
8878@item disassemble
d14508fe 8879@itemx disassemble /m
6ff0ba5f 8880@itemx disassemble /s
9b117ef3 8881@itemx disassemble /r
c906108c 8882This specialized command dumps a range of memory as machine
d14508fe 8883instructions. It can also print mixed source+disassembly by specifying
6ff0ba5f
DE
8884the @code{/m} or @code{/s} modifier and print the raw instructions in hex
8885as well as in symbolic form by specifying the @code{/r} modifier.
d14508fe 8886The default memory range is the function surrounding the
c906108c
SS
8887program counter of the selected frame. A single argument to this
8888command is a program counter value; @value{GDBN} dumps the function
21a0512e
PP
8889surrounding this value. When two arguments are given, they should
8890be separated by a comma, possibly surrounded by whitespace. The
53a71c06
CR
8891arguments specify a range of addresses to dump, in one of two forms:
8892
8893@table @code
8894@item @var{start},@var{end}
8895the addresses from @var{start} (inclusive) to @var{end} (exclusive)
8896@item @var{start},+@var{length}
8897the addresses from @var{start} (inclusive) to
8898@code{@var{start}+@var{length}} (exclusive).
8899@end table
8900
8901@noindent
8902When 2 arguments are specified, the name of the function is also
8903printed (since there could be several functions in the given range).
21a0512e
PP
8904
8905The argument(s) can be any expression yielding a numeric value, such as
8906@samp{0x32c4}, @samp{&main+10} or @samp{$pc - 8}.
2b28d209
PP
8907
8908If the range of memory being disassembled contains current program counter,
8909the instruction at that location is shown with a @code{=>} marker.
c906108c
SS
8910@end table
8911
c906108c
SS
8912The following example shows the disassembly of a range of addresses of
8913HP PA-RISC 2.0 code:
8914
8915@smallexample
21a0512e 8916(@value{GDBP}) disas 0x32c4, 0x32e4
c906108c 8917Dump of assembler code from 0x32c4 to 0x32e4:
2b28d209
PP
8918 0x32c4 <main+204>: addil 0,dp
8919 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
8920 0x32cc <main+212>: ldil 0x3000,r31
8921 0x32d0 <main+216>: ble 0x3f8(sr4,r31)
8922 0x32d4 <main+220>: ldo 0(r31),rp
8923 0x32d8 <main+224>: addil -0x800,dp
8924 0x32dc <main+228>: ldo 0x588(r1),r26
8925 0x32e0 <main+232>: ldil 0x3000,r31
c906108c
SS
8926End of assembler dump.
8927@end smallexample
c906108c 8928
6ff0ba5f
DE
8929Here is an example showing mixed source+assembly for Intel x86
8930with @code{/m} or @code{/s}, when the program is stopped just after
8931function prologue in a non-optimized function with no inline code.
d14508fe
DE
8932
8933@smallexample
8934(@value{GDBP}) disas /m main
8935Dump of assembler code for function main:
89365 @{
9c419145
PP
8937 0x08048330 <+0>: push %ebp
8938 0x08048331 <+1>: mov %esp,%ebp
8939 0x08048333 <+3>: sub $0x8,%esp
8940 0x08048336 <+6>: and $0xfffffff0,%esp
8941 0x08048339 <+9>: sub $0x10,%esp
d14508fe
DE
8942
89436 printf ("Hello.\n");
9c419145
PP
8944=> 0x0804833c <+12>: movl $0x8048440,(%esp)
8945 0x08048343 <+19>: call 0x8048284 <puts@@plt>
d14508fe
DE
8946
89477 return 0;
89488 @}
9c419145
PP
8949 0x08048348 <+24>: mov $0x0,%eax
8950 0x0804834d <+29>: leave
8951 0x0804834e <+30>: ret
d14508fe
DE
8952
8953End of assembler dump.
8954@end smallexample
8955
6ff0ba5f
DE
8956The @code{/m} option is deprecated as its output is not useful when
8957there is either inlined code or re-ordered code.
8958The @code{/s} option is the preferred choice.
8959Here is an example for AMD x86-64 showing the difference between
8960@code{/m} output and @code{/s} output.
8961This example has one inline function defined in a header file,
8962and the code is compiled with @samp{-O2} optimization.
8963Note how the @code{/m} output is missing the disassembly of
8964several instructions that are present in the @code{/s} output.
8965
8966@file{foo.h}:
8967
8968@smallexample
8969int
8970foo (int a)
8971@{
8972 if (a < 0)
8973 return a * 2;
8974 if (a == 0)
8975 return 1;
8976 return a + 10;
8977@}
8978@end smallexample
8979
8980@file{foo.c}:
8981
8982@smallexample
8983#include "foo.h"
8984volatile int x, y;
8985int
8986main ()
8987@{
8988 x = foo (y);
8989 return 0;
8990@}
8991@end smallexample
8992
8993@smallexample
8994(@value{GDBP}) disas /m main
8995Dump of assembler code for function main:
89965 @{
8997
89986 x = foo (y);
8999 0x0000000000400400 <+0>: mov 0x200c2e(%rip),%eax # 0x601034 <y>
9000 0x0000000000400417 <+23>: mov %eax,0x200c13(%rip) # 0x601030 <x>
9001
90027 return 0;
90038 @}
9004 0x000000000040041d <+29>: xor %eax,%eax
9005 0x000000000040041f <+31>: retq
9006 0x0000000000400420 <+32>: add %eax,%eax
9007 0x0000000000400422 <+34>: jmp 0x400417 <main+23>
9008
9009End of assembler dump.
9010(@value{GDBP}) disas /s main
9011Dump of assembler code for function main:
9012foo.c:
90135 @{
90146 x = foo (y);
9015 0x0000000000400400 <+0>: mov 0x200c2e(%rip),%eax # 0x601034 <y>
9016
9017foo.h:
90184 if (a < 0)
9019 0x0000000000400406 <+6>: test %eax,%eax
9020 0x0000000000400408 <+8>: js 0x400420 <main+32>
9021
90226 if (a == 0)
90237 return 1;
90248 return a + 10;
9025 0x000000000040040a <+10>: lea 0xa(%rax),%edx
9026 0x000000000040040d <+13>: test %eax,%eax
9027 0x000000000040040f <+15>: mov $0x1,%eax
9028 0x0000000000400414 <+20>: cmovne %edx,%eax
9029
9030foo.c:
90316 x = foo (y);
9032 0x0000000000400417 <+23>: mov %eax,0x200c13(%rip) # 0x601030 <x>
9033
90347 return 0;
90358 @}
9036 0x000000000040041d <+29>: xor %eax,%eax
9037 0x000000000040041f <+31>: retq
9038
9039foo.h:
90405 return a * 2;
9041 0x0000000000400420 <+32>: add %eax,%eax
9042 0x0000000000400422 <+34>: jmp 0x400417 <main+23>
9043End of assembler dump.
9044@end smallexample
9045
53a71c06
CR
9046Here is another example showing raw instructions in hex for AMD x86-64,
9047
9048@smallexample
9049(gdb) disas /r 0x400281,+10
9050Dump of assembler code from 0x400281 to 0x40028b:
9051 0x0000000000400281: 38 36 cmp %dh,(%rsi)
9052 0x0000000000400283: 2d 36 34 2e 73 sub $0x732e3436,%eax
9053 0x0000000000400288: 6f outsl %ds:(%rsi),(%dx)
9054 0x0000000000400289: 2e 32 00 xor %cs:(%rax),%al
9055End of assembler dump.
9056@end smallexample
9057
629500fa 9058Addresses cannot be specified as a location (@pxref{Specify Location}).
7e1e0340
DE
9059So, for example, if you want to disassemble function @code{bar}
9060in file @file{foo.c}, you must type @samp{disassemble 'foo.c'::bar}
9061and not @samp{disassemble foo.c:bar}.
9062
c906108c
SS
9063Some architectures have more than one commonly-used set of instruction
9064mnemonics or other syntax.
9065
76d17f34
EZ
9066For programs that were dynamically linked and use shared libraries,
9067instructions that call functions or branch to locations in the shared
9068libraries might show a seemingly bogus location---it's actually a
9069location of the relocation table. On some architectures, @value{GDBN}
9070might be able to resolve these to actual function names.
9071
65b48a81
PB
9072@table @code
9073@kindex set disassembler-options
9074@cindex disassembler options
9075@item set disassembler-options @var{option1}[,@var{option2}@dots{}]
9076This command controls the passing of target specific information to
9077the disassembler. For a list of valid options, please refer to the
9078@code{-M}/@code{--disassembler-options} section of the @samp{objdump}
9079manual and/or the output of @kbd{objdump --help}
f5a476a7 9080(@pxref{objdump,,objdump,binutils,The GNU Binary Utilities}).
65b48a81
PB
9081The default value is the empty string.
9082
9083If it is necessary to specify more than one disassembler option, then
9084multiple options can be placed together into a comma separated list.
471b9d15 9085Currently this command is only supported on targets ARM, MIPS, PowerPC
65b48a81
PB
9086and S/390.
9087
9088@kindex show disassembler-options
9089@item show disassembler-options
9090Show the current setting of the disassembler options.
9091@end table
9092
c906108c 9093@table @code
d4f3574e 9094@kindex set disassembly-flavor
d4f3574e
SS
9095@cindex Intel disassembly flavor
9096@cindex AT&T disassembly flavor
9097@item set disassembly-flavor @var{instruction-set}
c906108c
SS
9098Select the instruction set to use when disassembling the
9099program via the @code{disassemble} or @code{x/i} commands.
9100
9101Currently this command is only defined for the Intel x86 family. You
d4f3574e
SS
9102can set @var{instruction-set} to either @code{intel} or @code{att}.
9103The default is @code{att}, the AT&T flavor used by default by Unix
9104assemblers for x86-based targets.
9c16f35a
EZ
9105
9106@kindex show disassembly-flavor
9107@item show disassembly-flavor
9108Show the current setting of the disassembly flavor.
c906108c
SS
9109@end table
9110
91440f57
HZ
9111@table @code
9112@kindex set disassemble-next-line
9113@kindex show disassemble-next-line
9114@item set disassemble-next-line
9115@itemx show disassemble-next-line
32ae1842
EZ
9116Control whether or not @value{GDBN} will disassemble the next source
9117line or instruction when execution stops. If ON, @value{GDBN} will
9118display disassembly of the next source line when execution of the
9119program being debugged stops. This is @emph{in addition} to
9120displaying the source line itself, which @value{GDBN} always does if
9121possible. If the next source line cannot be displayed for some reason
9122(e.g., if @value{GDBN} cannot find the source file, or there's no line
9123info in the debug info), @value{GDBN} will display disassembly of the
9124next @emph{instruction} instead of showing the next source line. If
9125AUTO, @value{GDBN} will display disassembly of next instruction only
9126if the source line cannot be displayed. This setting causes
9127@value{GDBN} to display some feedback when you step through a function
9128with no line info or whose source file is unavailable. The default is
9129OFF, which means never display the disassembly of the next line or
9130instruction.
91440f57
HZ
9131@end table
9132
c906108c 9133
6d2ebf8b 9134@node Data
c906108c
SS
9135@chapter Examining Data
9136
9137@cindex printing data
9138@cindex examining data
9139@kindex print
9140@kindex inspect
c906108c 9141The usual way to examine data in your program is with the @code{print}
7a292a7a
SS
9142command (abbreviated @code{p}), or its synonym @code{inspect}. It
9143evaluates and prints the value of an expression of the language your
9144program is written in (@pxref{Languages, ,Using @value{GDBN} with
78e2826b
TT
9145Different Languages}). It may also print the expression using a
9146Python-based pretty-printer (@pxref{Pretty Printing}).
c906108c
SS
9147
9148@table @code
d4f3574e
SS
9149@item print @var{expr}
9150@itemx print /@var{f} @var{expr}
9151@var{expr} is an expression (in the source language). By default the
9152value of @var{expr} is printed in a format appropriate to its data type;
c906108c 9153you can choose a different format by specifying @samp{/@var{f}}, where
d4f3574e 9154@var{f} is a letter specifying the format; see @ref{Output Formats,,Output
79a6e687 9155Formats}.
c906108c
SS
9156
9157@item print
9158@itemx print /@var{f}
15387254 9159@cindex reprint the last value
d4f3574e 9160If you omit @var{expr}, @value{GDBN} displays the last value again (from the
79a6e687 9161@dfn{value history}; @pxref{Value History, ,Value History}). This allows you to
c906108c
SS
9162conveniently inspect the same value in an alternative format.
9163@end table
9164
9165A more low-level way of examining data is with the @code{x} command.
9166It examines data in memory at a specified address and prints it in a
79a6e687 9167specified format. @xref{Memory, ,Examining Memory}.
c906108c 9168
7a292a7a 9169If you are interested in information about types, or about how the
d4f3574e
SS
9170fields of a struct or a class are declared, use the @code{ptype @var{exp}}
9171command rather than @code{print}. @xref{Symbols, ,Examining the Symbol
7a292a7a 9172Table}.
c906108c 9173
06fc020f
SCR
9174@cindex exploring hierarchical data structures
9175@kindex explore
9176Another way of examining values of expressions and type information is
9177through the Python extension command @code{explore} (available only if
9178the @value{GDBN} build is configured with @code{--with-python}). It
9179offers an interactive way to start at the highest level (or, the most
9180abstract level) of the data type of an expression (or, the data type
9181itself) and explore all the way down to leaf scalar values/fields
9182embedded in the higher level data types.
9183
9184@table @code
9185@item explore @var{arg}
9186@var{arg} is either an expression (in the source language), or a type
9187visible in the current context of the program being debugged.
9188@end table
9189
9190The working of the @code{explore} command can be illustrated with an
9191example. If a data type @code{struct ComplexStruct} is defined in your
9192C program as
9193
9194@smallexample
9195struct SimpleStruct
9196@{
9197 int i;
9198 double d;
9199@};
9200
9201struct ComplexStruct
9202@{
9203 struct SimpleStruct *ss_p;
9204 int arr[10];
9205@};
9206@end smallexample
9207
9208@noindent
9209followed by variable declarations as
9210
9211@smallexample
9212struct SimpleStruct ss = @{ 10, 1.11 @};
9213struct ComplexStruct cs = @{ &ss, @{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 @} @};
9214@end smallexample
9215
9216@noindent
9217then, the value of the variable @code{cs} can be explored using the
9218@code{explore} command as follows.
9219
9220@smallexample
9221(gdb) explore cs
9222The value of `cs' is a struct/class of type `struct ComplexStruct' with
9223the following fields:
9224
9225 ss_p = <Enter 0 to explore this field of type `struct SimpleStruct *'>
9226 arr = <Enter 1 to explore this field of type `int [10]'>
9227
9228Enter the field number of choice:
9229@end smallexample
9230
9231@noindent
9232Since the fields of @code{cs} are not scalar values, you are being
9233prompted to chose the field you want to explore. Let's say you choose
9234the field @code{ss_p} by entering @code{0}. Then, since this field is a
9235pointer, you will be asked if it is pointing to a single value. From
9236the declaration of @code{cs} above, it is indeed pointing to a single
9237value, hence you enter @code{y}. If you enter @code{n}, then you will
9238be asked if it were pointing to an array of values, in which case this
9239field will be explored as if it were an array.
9240
9241@smallexample
9242`cs.ss_p' is a pointer to a value of type `struct SimpleStruct'
9243Continue exploring it as a pointer to a single value [y/n]: y
9244The value of `*(cs.ss_p)' is a struct/class of type `struct
9245SimpleStruct' with the following fields:
9246
9247 i = 10 .. (Value of type `int')
9248 d = 1.1100000000000001 .. (Value of type `double')
9249
9250Press enter to return to parent value:
9251@end smallexample
9252
9253@noindent
9254If the field @code{arr} of @code{cs} was chosen for exploration by
9255entering @code{1} earlier, then since it is as array, you will be
9256prompted to enter the index of the element in the array that you want
9257to explore.
9258
9259@smallexample
9260`cs.arr' is an array of `int'.
9261Enter the index of the element you want to explore in `cs.arr': 5
9262
9263`(cs.arr)[5]' is a scalar value of type `int'.
9264
9265(cs.arr)[5] = 4
9266
9267Press enter to return to parent value:
9268@end smallexample
9269
9270In general, at any stage of exploration, you can go deeper towards the
9271leaf values by responding to the prompts appropriately, or hit the
9272return key to return to the enclosing data structure (the @i{higher}
9273level data structure).
9274
9275Similar to exploring values, you can use the @code{explore} command to
9276explore types. Instead of specifying a value (which is typically a
9277variable name or an expression valid in the current context of the
9278program being debugged), you specify a type name. If you consider the
9279same example as above, your can explore the type
9280@code{struct ComplexStruct} by passing the argument
9281@code{struct ComplexStruct} to the @code{explore} command.
9282
9283@smallexample
9284(gdb) explore struct ComplexStruct
9285@end smallexample
9286
9287@noindent
9288By responding to the prompts appropriately in the subsequent interactive
9289session, you can explore the type @code{struct ComplexStruct} in a
9290manner similar to how the value @code{cs} was explored in the above
9291example.
9292
9293The @code{explore} command also has two sub-commands,
9294@code{explore value} and @code{explore type}. The former sub-command is
9295a way to explicitly specify that value exploration of the argument is
9296being invoked, while the latter is a way to explicitly specify that type
9297exploration of the argument is being invoked.
9298
9299@table @code
9300@item explore value @var{expr}
9301@cindex explore value
9302This sub-command of @code{explore} explores the value of the
9303expression @var{expr} (if @var{expr} is an expression valid in the
9304current context of the program being debugged). The behavior of this
9305command is identical to that of the behavior of the @code{explore}
9306command being passed the argument @var{expr}.
9307
9308@item explore type @var{arg}
9309@cindex explore type
9310This sub-command of @code{explore} explores the type of @var{arg} (if
9311@var{arg} is a type visible in the current context of program being
9312debugged), or the type of the value/expression @var{arg} (if @var{arg}
9313is an expression valid in the current context of the program being
9314debugged). If @var{arg} is a type, then the behavior of this command is
9315identical to that of the @code{explore} command being passed the
9316argument @var{arg}. If @var{arg} is an expression, then the behavior of
9317this command will be identical to that of the @code{explore} command
9318being passed the type of @var{arg} as the argument.
9319@end table
9320
c906108c
SS
9321@menu
9322* Expressions:: Expressions
6ba66d6a 9323* Ambiguous Expressions:: Ambiguous Expressions
c906108c
SS
9324* Variables:: Program variables
9325* Arrays:: Artificial arrays
9326* Output Formats:: Output formats
9327* Memory:: Examining memory
9328* Auto Display:: Automatic display
9329* Print Settings:: Print settings
4c374409 9330* Pretty Printing:: Python pretty printing
c906108c
SS
9331* Value History:: Value history
9332* Convenience Vars:: Convenience variables
a72c3253 9333* Convenience Funs:: Convenience functions
c906108c 9334* Registers:: Registers
c906108c 9335* Floating Point Hardware:: Floating point hardware
53c69bd7 9336* Vector Unit:: Vector Unit
721c2651 9337* OS Information:: Auxiliary data provided by operating system
29e57380 9338* Memory Region Attributes:: Memory region attributes
16d9dec6 9339* Dump/Restore Files:: Copy between memory and a file
384ee23f 9340* Core File Generation:: Cause a program dump its core
a0eb71c5
KB
9341* Character Sets:: Debugging programs that use a different
9342 character set than GDB does
b12039c6 9343* Caching Target Data:: Data caching for targets
08388c79 9344* Searching Memory:: Searching memory for a sequence of bytes
5fdf6324 9345* Value Sizes:: Managing memory allocated for values
c906108c
SS
9346@end menu
9347
6d2ebf8b 9348@node Expressions
c906108c
SS
9349@section Expressions
9350
9351@cindex expressions
9352@code{print} and many other @value{GDBN} commands accept an expression and
9353compute its value. Any kind of constant, variable or operator defined
9354by the programming language you are using is valid in an expression in
e2e0bcd1
JB
9355@value{GDBN}. This includes conditional expressions, function calls,
9356casts, and string constants. It also includes preprocessor macros, if
9357you compiled your program to include this information; see
9358@ref{Compilation}.
c906108c 9359
15387254 9360@cindex arrays in expressions
d4f3574e
SS
9361@value{GDBN} supports array constants in expressions input by
9362the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example,
63092375
DJ
9363you can use the command @code{print @{1, 2, 3@}} to create an array
9364of three integers. If you pass an array to a function or assign it
9365to a program variable, @value{GDBN} copies the array to memory that
9366is @code{malloc}ed in the target program.
c906108c 9367
c906108c
SS
9368Because C is so widespread, most of the expressions shown in examples in
9369this manual are in C. @xref{Languages, , Using @value{GDBN} with Different
9370Languages}, for information on how to use expressions in other
9371languages.
9372
9373In this section, we discuss operators that you can use in @value{GDBN}
9374expressions regardless of your programming language.
9375
15387254 9376@cindex casts, in expressions
c906108c
SS
9377Casts are supported in all languages, not just in C, because it is so
9378useful to cast a number into a pointer in order to examine a structure
9379at that address in memory.
9380@c FIXME: casts supported---Mod2 true?
c906108c
SS
9381
9382@value{GDBN} supports these operators, in addition to those common
9383to programming languages:
9384
9385@table @code
9386@item @@
9387@samp{@@} is a binary operator for treating parts of memory as arrays.
79a6e687 9388@xref{Arrays, ,Artificial Arrays}, for more information.
c906108c
SS
9389
9390@item ::
9391@samp{::} allows you to specify a variable in terms of the file or
79a6e687 9392function where it is defined. @xref{Variables, ,Program Variables}.
c906108c
SS
9393
9394@cindex @{@var{type}@}
9395@cindex type casting memory
9396@cindex memory, viewing as typed object
9397@cindex casts, to view memory
9398@item @{@var{type}@} @var{addr}
9399Refers to an object of type @var{type} stored at address @var{addr} in
697aa1b7
EZ
9400memory. The address @var{addr} may be any expression whose value is
9401an integer or pointer (but parentheses are required around binary
9402operators, just as in a cast). This construct is allowed regardless
9403of what kind of data is normally supposed to reside at @var{addr}.
c906108c
SS
9404@end table
9405
6ba66d6a
JB
9406@node Ambiguous Expressions
9407@section Ambiguous Expressions
9408@cindex ambiguous expressions
9409
9410Expressions can sometimes contain some ambiguous elements. For instance,
9411some programming languages (notably Ada, C@t{++} and Objective-C) permit
9412a single function name to be defined several times, for application in
9413different contexts. This is called @dfn{overloading}. Another example
9414involving Ada is generics. A @dfn{generic package} is similar to C@t{++}
9415templates and is typically instantiated several times, resulting in
9416the same function name being defined in different contexts.
9417
9418In some cases and depending on the language, it is possible to adjust
9419the expression to remove the ambiguity. For instance in C@t{++}, you
9420can specify the signature of the function you want to break on, as in
9421@kbd{break @var{function}(@var{types})}. In Ada, using the fully
9422qualified name of your function often makes the expression unambiguous
9423as well.
9424
9425When an ambiguity that needs to be resolved is detected, the debugger
9426has the capability to display a menu of numbered choices for each
9427possibility, and then waits for the selection with the prompt @samp{>}.
9428The first option is always @samp{[0] cancel}, and typing @kbd{0 @key{RET}}
9429aborts the current command. If the command in which the expression was
9430used allows more than one choice to be selected, the next option in the
9431menu is @samp{[1] all}, and typing @kbd{1 @key{RET}} selects all possible
9432choices.
9433
9434For example, the following session excerpt shows an attempt to set a
9435breakpoint at the overloaded symbol @code{String::after}.
9436We choose three particular definitions of that function name:
9437
9438@c FIXME! This is likely to change to show arg type lists, at least
9439@smallexample
9440@group
9441(@value{GDBP}) b String::after
9442[0] cancel
9443[1] all
9444[2] file:String.cc; line number:867
9445[3] file:String.cc; line number:860
9446[4] file:String.cc; line number:875
9447[5] file:String.cc; line number:853
9448[6] file:String.cc; line number:846
9449[7] file:String.cc; line number:735
9450> 2 4 6
9451Breakpoint 1 at 0xb26c: file String.cc, line 867.
9452Breakpoint 2 at 0xb344: file String.cc, line 875.
9453Breakpoint 3 at 0xafcc: file String.cc, line 846.
9454Multiple breakpoints were set.
9455Use the "delete" command to delete unwanted
9456 breakpoints.
9457(@value{GDBP})
9458@end group
9459@end smallexample
9460
9461@table @code
9462@kindex set multiple-symbols
9463@item set multiple-symbols @var{mode}
9464@cindex multiple-symbols menu
9465
9466This option allows you to adjust the debugger behavior when an expression
9467is ambiguous.
9468
9469By default, @var{mode} is set to @code{all}. If the command with which
9470the expression is used allows more than one choice, then @value{GDBN}
9471automatically selects all possible choices. For instance, inserting
9472a breakpoint on a function using an ambiguous name results in a breakpoint
9473inserted on each possible match. However, if a unique choice must be made,
9474then @value{GDBN} uses the menu to help you disambiguate the expression.
9475For instance, printing the address of an overloaded function will result
9476in the use of the menu.
9477
9478When @var{mode} is set to @code{ask}, the debugger always uses the menu
9479when an ambiguity is detected.
9480
9481Finally, when @var{mode} is set to @code{cancel}, the debugger reports
9482an error due to the ambiguity and the command is aborted.
9483
9484@kindex show multiple-symbols
9485@item show multiple-symbols
9486Show the current value of the @code{multiple-symbols} setting.
9487@end table
9488
6d2ebf8b 9489@node Variables
79a6e687 9490@section Program Variables
c906108c
SS
9491
9492The most common kind of expression to use is the name of a variable
9493in your program.
9494
9495Variables in expressions are understood in the selected stack frame
79a6e687 9496(@pxref{Selection, ,Selecting a Frame}); they must be either:
c906108c
SS
9497
9498@itemize @bullet
9499@item
9500global (or file-static)
9501@end itemize
9502
5d161b24 9503@noindent or
c906108c
SS
9504
9505@itemize @bullet
9506@item
9507visible according to the scope rules of the
9508programming language from the point of execution in that frame
5d161b24 9509@end itemize
c906108c
SS
9510
9511@noindent This means that in the function
9512
474c8240 9513@smallexample
c906108c
SS
9514foo (a)
9515 int a;
9516@{
9517 bar (a);
9518 @{
9519 int b = test ();
9520 bar (b);
9521 @}
9522@}
474c8240 9523@end smallexample
c906108c
SS
9524
9525@noindent
9526you can examine and use the variable @code{a} whenever your program is
9527executing within the function @code{foo}, but you can only use or
9528examine the variable @code{b} while your program is executing inside
9529the block where @code{b} is declared.
9530
9531@cindex variable name conflict
9532There is an exception: you can refer to a variable or function whose
9533scope is a single source file even if the current execution point is not
9534in this file. But it is possible to have more than one such variable or
9535function with the same name (in different source files). If that
9536happens, referring to that name has unpredictable effects. If you wish,
72384ba3 9537you can specify a static variable in a particular function or file by
15387254 9538using the colon-colon (@code{::}) notation:
c906108c 9539
d4f3574e 9540@cindex colon-colon, context for variables/functions
12c27660 9541@ifnotinfo
c906108c 9542@c info cannot cope with a :: index entry, but why deprive hard copy readers?
41afff9a 9543@cindex @code{::}, context for variables/functions
12c27660 9544@end ifnotinfo
474c8240 9545@smallexample
c906108c
SS
9546@var{file}::@var{variable}
9547@var{function}::@var{variable}
474c8240 9548@end smallexample
c906108c
SS
9549
9550@noindent
9551Here @var{file} or @var{function} is the name of the context for the
9552static @var{variable}. In the case of file names, you can use quotes to
9553make sure @value{GDBN} parses the file name as a single word---for example,
9554to print a global value of @code{x} defined in @file{f2.c}:
9555
474c8240 9556@smallexample
c906108c 9557(@value{GDBP}) p 'f2.c'::x
474c8240 9558@end smallexample
c906108c 9559
72384ba3
PH
9560The @code{::} notation is normally used for referring to
9561static variables, since you typically disambiguate uses of local variables
9562in functions by selecting the appropriate frame and using the
9563simple name of the variable. However, you may also use this notation
9564to refer to local variables in frames enclosing the selected frame:
9565
9566@smallexample
9567void
9568foo (int a)
9569@{
9570 if (a < 10)
9571 bar (a);
9572 else
9573 process (a); /* Stop here */
9574@}
9575
9576int
9577bar (int a)
9578@{
9579 foo (a + 5);
9580@}
9581@end smallexample
9582
9583@noindent
9584For example, if there is a breakpoint at the commented line,
9585here is what you might see
9586when the program stops after executing the call @code{bar(0)}:
9587
9588@smallexample
9589(@value{GDBP}) p a
9590$1 = 10
9591(@value{GDBP}) p bar::a
9592$2 = 5
9593(@value{GDBP}) up 2
9594#2 0x080483d0 in foo (a=5) at foobar.c:12
9595(@value{GDBP}) p a
9596$3 = 5
9597(@value{GDBP}) p bar::a
9598$4 = 0
9599@end smallexample
9600
b37052ae 9601@cindex C@t{++} scope resolution
805e1f19
TT
9602These uses of @samp{::} are very rarely in conflict with the very
9603similar use of the same notation in C@t{++}. When they are in
9604conflict, the C@t{++} meaning takes precedence; however, this can be
9605overridden by quoting the file or function name with single quotes.
9606
9607For example, suppose the program is stopped in a method of a class
9608that has a field named @code{includefile}, and there is also an
9609include file named @file{includefile} that defines a variable,
9610@code{some_global}.
9611
9612@smallexample
9613(@value{GDBP}) p includefile
9614$1 = 23
9615(@value{GDBP}) p includefile::some_global
9616A syntax error in expression, near `'.
9617(@value{GDBP}) p 'includefile'::some_global
9618$2 = 27
9619@end smallexample
c906108c
SS
9620
9621@cindex wrong values
9622@cindex variable values, wrong
15387254
EZ
9623@cindex function entry/exit, wrong values of variables
9624@cindex optimized code, wrong values of variables
c906108c
SS
9625@quotation
9626@emph{Warning:} Occasionally, a local variable may appear to have the
9627wrong value at certain points in a function---just after entry to a new
9628scope, and just before exit.
9629@end quotation
9630You may see this problem when you are stepping by machine instructions.
9631This is because, on most machines, it takes more than one instruction to
9632set up a stack frame (including local variable definitions); if you are
9633stepping by machine instructions, variables may appear to have the wrong
9634values until the stack frame is completely built. On exit, it usually
9635also takes more than one machine instruction to destroy a stack frame;
9636after you begin stepping through that group of instructions, local
9637variable definitions may be gone.
9638
9639This may also happen when the compiler does significant optimizations.
9640To be sure of always seeing accurate values, turn off all optimization
9641when compiling.
9642
d4f3574e
SS
9643@cindex ``No symbol "foo" in current context''
9644Another possible effect of compiler optimizations is to optimize
9645unused variables out of existence, or assign variables to registers (as
9646opposed to memory addresses). Depending on the support for such cases
9647offered by the debug info format used by the compiler, @value{GDBN}
9648might not be able to display values for such local variables. If that
9649happens, @value{GDBN} will print a message like this:
9650
474c8240 9651@smallexample
d4f3574e 9652No symbol "foo" in current context.
474c8240 9653@end smallexample
d4f3574e
SS
9654
9655To solve such problems, either recompile without optimizations, or use a
9656different debug info format, if the compiler supports several such
e0f8f636
TT
9657formats. @xref{Compilation}, for more information on choosing compiler
9658options. @xref{C, ,C and C@t{++}}, for more information about debug
9659info formats that are best suited to C@t{++} programs.
d4f3574e 9660
ab1adacd
EZ
9661If you ask to print an object whose contents are unknown to
9662@value{GDBN}, e.g., because its data type is not completely specified
9663by the debug information, @value{GDBN} will say @samp{<incomplete
9664type>}. @xref{Symbols, incomplete type}, for more about this.
9665
d69cf9b2
PA
9666@cindex no debug info variables
9667If you try to examine or use the value of a (global) variable for
9668which @value{GDBN} has no type information, e.g., because the program
9669includes no debug information, @value{GDBN} displays an error message.
9670@xref{Symbols, unknown type}, for more about unknown types. If you
9671cast the variable to its declared type, @value{GDBN} gets the
9672variable's value using the cast-to type as the variable's type. For
9673example, in a C program:
9674
9675@smallexample
9676 (@value{GDBP}) p var
9677 'var' has unknown type; cast it to its declared type
9678 (@value{GDBP}) p (float) var
9679 $1 = 3.14
9680@end smallexample
9681
36b11add
JK
9682If you append @kbd{@@entry} string to a function parameter name you get its
9683value at the time the function got called. If the value is not available an
9684error message is printed. Entry values are available only with some compilers.
9685Entry values are normally also printed at the function parameter list according
9686to @ref{set print entry-values}.
9687
9688@smallexample
9689Breakpoint 1, d (i=30) at gdb.base/entry-value.c:29
969029 i++;
9691(gdb) next
969230 e (i);
9693(gdb) print i
9694$1 = 31
9695(gdb) print i@@entry
9696$2 = 30
9697@end smallexample
9698
3a60f64e
JK
9699Strings are identified as arrays of @code{char} values without specified
9700signedness. Arrays of either @code{signed char} or @code{unsigned char} get
9701printed as arrays of 1 byte sized integers. @code{-fsigned-char} or
9702@code{-funsigned-char} @value{NGCC} options have no effect as @value{GDBN}
9703defines literal string type @code{"char"} as @code{char} without a sign.
9704For program code
9705
9706@smallexample
9707char var0[] = "A";
9708signed char var1[] = "A";
9709@end smallexample
9710
9711You get during debugging
9712@smallexample
9713(gdb) print var0
9714$1 = "A"
9715(gdb) print var1
9716$2 = @{65 'A', 0 '\0'@}
9717@end smallexample
9718
6d2ebf8b 9719@node Arrays
79a6e687 9720@section Artificial Arrays
c906108c
SS
9721
9722@cindex artificial array
15387254 9723@cindex arrays
41afff9a 9724@kindex @@@r{, referencing memory as an array}
c906108c
SS
9725It is often useful to print out several successive objects of the
9726same type in memory; a section of an array, or an array of
9727dynamically determined size for which only a pointer exists in the
9728program.
9729
9730You can do this by referring to a contiguous span of memory as an
9731@dfn{artificial array}, using the binary operator @samp{@@}. The left
9732operand of @samp{@@} should be the first element of the desired array
9733and be an individual object. The right operand should be the desired length
9734of the array. The result is an array value whose elements are all of
9735the type of the left argument. The first element is actually the left
9736argument; the second element comes from bytes of memory immediately
9737following those that hold the first element, and so on. Here is an
9738example. If a program says
9739
474c8240 9740@smallexample
c906108c 9741int *array = (int *) malloc (len * sizeof (int));
474c8240 9742@end smallexample
c906108c
SS
9743
9744@noindent
9745you can print the contents of @code{array} with
9746
474c8240 9747@smallexample
c906108c 9748p *array@@len
474c8240 9749@end smallexample
c906108c
SS
9750
9751The left operand of @samp{@@} must reside in memory. Array values made
9752with @samp{@@} in this way behave just like other arrays in terms of
9753subscripting, and are coerced to pointers when used in expressions.
9754Artificial arrays most often appear in expressions via the value history
79a6e687 9755(@pxref{Value History, ,Value History}), after printing one out.
c906108c
SS
9756
9757Another way to create an artificial array is to use a cast.
9758This re-interprets a value as if it were an array.
9759The value need not be in memory:
474c8240 9760@smallexample
c906108c
SS
9761(@value{GDBP}) p/x (short[2])0x12345678
9762$1 = @{0x1234, 0x5678@}
474c8240 9763@end smallexample
c906108c
SS
9764
9765As a convenience, if you leave the array length out (as in
c3f6f71d 9766@samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill
c906108c 9767the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}:
474c8240 9768@smallexample
c906108c
SS
9769(@value{GDBP}) p/x (short[])0x12345678
9770$2 = @{0x1234, 0x5678@}
474c8240 9771@end smallexample
c906108c
SS
9772
9773Sometimes the artificial array mechanism is not quite enough; in
9774moderately complex data structures, the elements of interest may not
9775actually be adjacent---for example, if you are interested in the values
9776of pointers in an array. One useful work-around in this situation is
9777to use a convenience variable (@pxref{Convenience Vars, ,Convenience
79a6e687 9778Variables}) as a counter in an expression that prints the first
c906108c
SS
9779interesting value, and then repeat that expression via @key{RET}. For
9780instance, suppose you have an array @code{dtab} of pointers to
9781structures, and you are interested in the values of a field @code{fv}
9782in each structure. Here is an example of what you might type:
9783
474c8240 9784@smallexample
c906108c
SS
9785set $i = 0
9786p dtab[$i++]->fv
9787@key{RET}
9788@key{RET}
9789@dots{}
474c8240 9790@end smallexample
c906108c 9791
6d2ebf8b 9792@node Output Formats
79a6e687 9793@section Output Formats
c906108c
SS
9794
9795@cindex formatted output
9796@cindex output formats
9797By default, @value{GDBN} prints a value according to its data type. Sometimes
9798this is not what you want. For example, you might want to print a number
9799in hex, or a pointer in decimal. Or you might want to view data in memory
9800at a certain address as a character string or as an instruction. To do
9801these things, specify an @dfn{output format} when you print a value.
9802
9803The simplest use of output formats is to say how to print a value
9804already computed. This is done by starting the arguments of the
9805@code{print} command with a slash and a format letter. The format
9806letters supported are:
9807
9808@table @code
9809@item x
9810Regard the bits of the value as an integer, and print the integer in
9811hexadecimal.
9812
9813@item d
9814Print as integer in signed decimal.
9815
9816@item u
9817Print as integer in unsigned decimal.
9818
9819@item o
9820Print as integer in octal.
9821
9822@item t
9823Print as integer in binary. The letter @samp{t} stands for ``two''.
9824@footnote{@samp{b} cannot be used because these format letters are also
9825used with the @code{x} command, where @samp{b} stands for ``byte'';
79a6e687 9826see @ref{Memory,,Examining Memory}.}
c906108c
SS
9827
9828@item a
9829@cindex unknown address, locating
3d67e040 9830@cindex locate address
c906108c
SS
9831Print as an address, both absolute in hexadecimal and as an offset from
9832the nearest preceding symbol. You can use this format used to discover
9833where (in what function) an unknown address is located:
9834
474c8240 9835@smallexample
c906108c
SS
9836(@value{GDBP}) p/a 0x54320
9837$3 = 0x54320 <_initialize_vx+396>
474c8240 9838@end smallexample
c906108c 9839
3d67e040
EZ
9840@noindent
9841The command @code{info symbol 0x54320} yields similar results.
9842@xref{Symbols, info symbol}.
9843
c906108c 9844@item c
51274035
EZ
9845Regard as an integer and print it as a character constant. This
9846prints both the numerical value and its character representation. The
9847character representation is replaced with the octal escape @samp{\nnn}
9848for characters outside the 7-bit @sc{ascii} range.
c906108c 9849
ea37ba09
DJ
9850Without this format, @value{GDBN} displays @code{char},
9851@w{@code{unsigned char}}, and @w{@code{signed char}} data as character
9852constants. Single-byte members of vectors are displayed as integer
9853data.
9854
c906108c
SS
9855@item f
9856Regard the bits of the value as a floating point number and print
9857using typical floating point syntax.
ea37ba09
DJ
9858
9859@item s
9860@cindex printing strings
9861@cindex printing byte arrays
9862Regard as a string, if possible. With this format, pointers to single-byte
9863data are displayed as null-terminated strings and arrays of single-byte data
9864are displayed as fixed-length strings. Other values are displayed in their
9865natural types.
9866
9867Without this format, @value{GDBN} displays pointers to and arrays of
9868@code{char}, @w{@code{unsigned char}}, and @w{@code{signed char}} as
9869strings. Single-byte members of a vector are displayed as an integer
9870array.
a6bac58e 9871
6fbe845e
AB
9872@item z
9873Like @samp{x} formatting, the value is treated as an integer and
9874printed as hexadecimal, but leading zeros are printed to pad the value
9875to the size of the integer type.
9876
a6bac58e
TT
9877@item r
9878@cindex raw printing
9879Print using the @samp{raw} formatting. By default, @value{GDBN} will
78e2826b
TT
9880use a Python-based pretty-printer, if one is available (@pxref{Pretty
9881Printing}). This typically results in a higher-level display of the
9882value's contents. The @samp{r} format bypasses any Python
9883pretty-printer which might exist.
c906108c
SS
9884@end table
9885
9886For example, to print the program counter in hex (@pxref{Registers}), type
9887
474c8240 9888@smallexample
c906108c 9889p/x $pc
474c8240 9890@end smallexample
c906108c
SS
9891
9892@noindent
9893Note that no space is required before the slash; this is because command
9894names in @value{GDBN} cannot contain a slash.
9895
9896To reprint the last value in the value history with a different format,
9897you can use the @code{print} command with just a format and no
9898expression. For example, @samp{p/x} reprints the last value in hex.
9899
6d2ebf8b 9900@node Memory
79a6e687 9901@section Examining Memory
c906108c
SS
9902
9903You can use the command @code{x} (for ``examine'') to examine memory in
9904any of several formats, independently of your program's data types.
9905
9906@cindex examining memory
9907@table @code
41afff9a 9908@kindex x @r{(examine memory)}
c906108c
SS
9909@item x/@var{nfu} @var{addr}
9910@itemx x @var{addr}
9911@itemx x
9912Use the @code{x} command to examine memory.
9913@end table
9914
9915@var{n}, @var{f}, and @var{u} are all optional parameters that specify how
9916much memory to display and how to format it; @var{addr} is an
9917expression giving the address where you want to start displaying memory.
9918If you use defaults for @var{nfu}, you need not type the slash @samp{/}.
9919Several commands set convenient defaults for @var{addr}.
9920
9921@table @r
9922@item @var{n}, the repeat count
9923The repeat count is a decimal integer; the default is 1. It specifies
bb556f1f
TK
9924how much memory (counting by units @var{u}) to display. If a negative
9925number is specified, memory is examined backward from @var{addr}.
c906108c
SS
9926@c This really is **decimal**; unaffected by 'set radix' as of GDB
9927@c 4.1.2.
9928
9929@item @var{f}, the display format
51274035
EZ
9930The display format is one of the formats used by @code{print}
9931(@samp{x}, @samp{d}, @samp{u}, @samp{o}, @samp{t}, @samp{a}, @samp{c},
ea37ba09
DJ
9932@samp{f}, @samp{s}), and in addition @samp{i} (for machine instructions).
9933The default is @samp{x} (hexadecimal) initially. The default changes
9934each time you use either @code{x} or @code{print}.
c906108c
SS
9935
9936@item @var{u}, the unit size
9937The unit size is any of
9938
9939@table @code
9940@item b
9941Bytes.
9942@item h
9943Halfwords (two bytes).
9944@item w
9945Words (four bytes). This is the initial default.
9946@item g
9947Giant words (eight bytes).
9948@end table
9949
9950Each time you specify a unit size with @code{x}, that size becomes the
9a22f0d0
PM
9951default unit the next time you use @code{x}. For the @samp{i} format,
9952the unit size is ignored and is normally not written. For the @samp{s} format,
9953the unit size defaults to @samp{b}, unless it is explicitly given.
9954Use @kbd{x /hs} to display 16-bit char strings and @kbd{x /ws} to display
995532-bit strings. The next use of @kbd{x /s} will again display 8-bit strings.
9956Note that the results depend on the programming language of the
9957current compilation unit. If the language is C, the @samp{s}
9958modifier will use the UTF-16 encoding while @samp{w} will use
9959UTF-32. The encoding is set by the programming language and cannot
9960be altered.
c906108c
SS
9961
9962@item @var{addr}, starting display address
9963@var{addr} is the address where you want @value{GDBN} to begin displaying
9964memory. The expression need not have a pointer value (though it may);
9965it is always interpreted as an integer address of a byte of memory.
9966@xref{Expressions, ,Expressions}, for more information on expressions. The default for
9967@var{addr} is usually just after the last address examined---but several
9968other commands also set the default address: @code{info breakpoints} (to
9969the address of the last breakpoint listed), @code{info line} (to the
9970starting address of a line), and @code{print} (if you use it to display
9971a value from memory).
9972@end table
9973
9974For example, @samp{x/3uh 0x54320} is a request to display three halfwords
9975(@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}),
9976starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four
9977words (@samp{w}) of memory above the stack pointer (here, @samp{$sp};
d4f3574e 9978@pxref{Registers, ,Registers}) in hexadecimal (@samp{x}).
c906108c 9979
bb556f1f
TK
9980You can also specify a negative repeat count to examine memory backward
9981from the given address. For example, @samp{x/-3uh 0x54320} prints three
9982halfwords (@code{h}) at @code{0x54314}, @code{0x54328}, and @code{0x5431c}.
9983
c906108c
SS
9984Since the letters indicating unit sizes are all distinct from the
9985letters specifying output formats, you do not have to remember whether
9986unit size or format comes first; either order works. The output
9987specifications @samp{4xw} and @samp{4wx} mean exactly the same thing.
9988(However, the count @var{n} must come first; @samp{wx4} does not work.)
9989
9990Even though the unit size @var{u} is ignored for the formats @samp{s}
9991and @samp{i}, you might still want to use a count @var{n}; for example,
9992@samp{3i} specifies that you want to see three machine instructions,
a4642986
MR
9993including any operands. For convenience, especially when used with
9994the @code{display} command, the @samp{i} format also prints branch delay
9995slot instructions, if any, beyond the count specified, which immediately
9996follow the last instruction that is within the count. The command
9997@code{disassemble} gives an alternative way of inspecting machine
9998instructions; see @ref{Machine Code,,Source and Machine Code}.
c906108c 9999
bb556f1f
TK
10000If a negative repeat count is specified for the formats @samp{s} or @samp{i},
10001the command displays null-terminated strings or instructions before the given
10002address as many as the absolute value of the given number. For the @samp{i}
10003format, we use line number information in the debug info to accurately locate
10004instruction boundaries while disassembling backward. If line info is not
10005available, the command stops examining memory with an error message.
10006
c906108c
SS
10007All the defaults for the arguments to @code{x} are designed to make it
10008easy to continue scanning memory with minimal specifications each time
10009you use @code{x}. For example, after you have inspected three machine
10010instructions with @samp{x/3i @var{addr}}, you can inspect the next seven
10011with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command,
10012the repeat count @var{n} is used again; the other arguments default as
10013for successive uses of @code{x}.
10014
2b28d209
PP
10015When examining machine instructions, the instruction at current program
10016counter is shown with a @code{=>} marker. For example:
10017
10018@smallexample
10019(@value{GDBP}) x/5i $pc-6
10020 0x804837f <main+11>: mov %esp,%ebp
10021 0x8048381 <main+13>: push %ecx
10022 0x8048382 <main+14>: sub $0x4,%esp
10023=> 0x8048385 <main+17>: movl $0x8048460,(%esp)
10024 0x804838c <main+24>: call 0x80482d4 <puts@@plt>
10025@end smallexample
10026
c906108c
SS
10027@cindex @code{$_}, @code{$__}, and value history
10028The addresses and contents printed by the @code{x} command are not saved
10029in the value history because there is often too much of them and they
10030would get in the way. Instead, @value{GDBN} makes these values available for
10031subsequent use in expressions as values of the convenience variables
10032@code{$_} and @code{$__}. After an @code{x} command, the last address
10033examined is available for use in expressions in the convenience variable
10034@code{$_}. The contents of that address, as examined, are available in
10035the convenience variable @code{$__}.
10036
10037If the @code{x} command has a repeat count, the address and contents saved
10038are from the last memory unit printed; this is not the same as the last
10039address printed if several units were printed on the last line of output.
10040
a86c90e6
SM
10041@anchor{addressable memory unit}
10042@cindex addressable memory unit
10043Most targets have an addressable memory unit size of 8 bits. This means
10044that to each memory address are associated 8 bits of data. Some
10045targets, however, have other addressable memory unit sizes.
10046Within @value{GDBN} and this document, the term
10047@dfn{addressable memory unit} (or @dfn{memory unit} for short) is used
10048when explicitly referring to a chunk of data of that size. The word
10049@dfn{byte} is used to refer to a chunk of data of 8 bits, regardless of
10050the addressable memory unit size of the target. For most systems,
10051addressable memory unit is a synonym of byte.
10052
09d4efe1 10053@cindex remote memory comparison
936d2992 10054@cindex target memory comparison
09d4efe1 10055@cindex verify remote memory image
936d2992 10056@cindex verify target memory image
09d4efe1 10057When you are debugging a program running on a remote target machine
936d2992
PA
10058(@pxref{Remote Debugging}), you may wish to verify the program's image
10059in the remote machine's memory against the executable file you
10060downloaded to the target. Or, on any target, you may want to check
10061whether the program has corrupted its own read-only sections. The
10062@code{compare-sections} command is provided for such situations.
09d4efe1
EZ
10063
10064@table @code
10065@kindex compare-sections
95cf3b38 10066@item compare-sections @r{[}@var{section-name}@r{|}@code{-r}@r{]}
09d4efe1
EZ
10067Compare the data of a loadable section @var{section-name} in the
10068executable file of the program being debugged with the same section in
936d2992 10069the target machine's memory, and report any mismatches. With no
95cf3b38 10070arguments, compares all loadable sections. With an argument of
936d2992
PA
10071@code{-r}, compares all loadable read-only sections.
10072
10073Note: for remote targets, this command can be accelerated if the
10074target supports computing the CRC checksum of a block of memory
10075(@pxref{qCRC packet}).
09d4efe1
EZ
10076@end table
10077
6d2ebf8b 10078@node Auto Display
79a6e687 10079@section Automatic Display
c906108c
SS
10080@cindex automatic display
10081@cindex display of expressions
10082
10083If you find that you want to print the value of an expression frequently
10084(to see how it changes), you might want to add it to the @dfn{automatic
10085display list} so that @value{GDBN} prints its value each time your program stops.
10086Each expression added to the list is given a number to identify it;
10087to remove an expression from the list, you specify that number.
10088The automatic display looks like this:
10089
474c8240 10090@smallexample
c906108c
SS
100912: foo = 38
100923: bar[5] = (struct hack *) 0x3804
474c8240 10093@end smallexample
c906108c
SS
10094
10095@noindent
10096This display shows item numbers, expressions and their current values. As with
10097displays you request manually using @code{x} or @code{print}, you can
10098specify the output format you prefer; in fact, @code{display} decides
ea37ba09
DJ
10099whether to use @code{print} or @code{x} depending your format
10100specification---it uses @code{x} if you specify either the @samp{i}
10101or @samp{s} format, or a unit size; otherwise it uses @code{print}.
c906108c
SS
10102
10103@table @code
10104@kindex display
d4f3574e
SS
10105@item display @var{expr}
10106Add the expression @var{expr} to the list of expressions to display
c906108c
SS
10107each time your program stops. @xref{Expressions, ,Expressions}.
10108
10109@code{display} does not repeat if you press @key{RET} again after using it.
10110
d4f3574e 10111@item display/@var{fmt} @var{expr}
c906108c 10112For @var{fmt} specifying only a display format and not a size or
d4f3574e 10113count, add the expression @var{expr} to the auto-display list but
c906108c 10114arrange to display it each time in the specified format @var{fmt}.
79a6e687 10115@xref{Output Formats,,Output Formats}.
c906108c
SS
10116
10117@item display/@var{fmt} @var{addr}
10118For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a
10119number of units, add the expression @var{addr} as a memory address to
10120be examined each time your program stops. Examining means in effect
79a6e687 10121doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining Memory}.
c906108c
SS
10122@end table
10123
10124For example, @samp{display/i $pc} can be helpful, to see the machine
10125instruction about to be executed each time execution stops (@samp{$pc}
d4f3574e 10126is a common name for the program counter; @pxref{Registers, ,Registers}).
c906108c
SS
10127
10128@table @code
10129@kindex delete display
10130@kindex undisplay
10131@item undisplay @var{dnums}@dots{}
10132@itemx delete display @var{dnums}@dots{}
c9174737
PA
10133Remove items from the list of expressions to display. Specify the
10134numbers of the displays that you want affected with the command
10135argument @var{dnums}. It can be a single display number, one of the
10136numbers shown in the first field of the @samp{info display} display;
10137or it could be a range of display numbers, as in @code{2-4}.
c906108c
SS
10138
10139@code{undisplay} does not repeat if you press @key{RET} after using it.
10140(Otherwise you would just get the error @samp{No display number @dots{}}.)
10141
10142@kindex disable display
10143@item disable display @var{dnums}@dots{}
10144Disable the display of item numbers @var{dnums}. A disabled display
10145item is not printed automatically, but is not forgotten. It may be
c9174737
PA
10146enabled again later. Specify the numbers of the displays that you
10147want affected with the command argument @var{dnums}. It can be a
10148single display number, one of the numbers shown in the first field of
10149the @samp{info display} display; or it could be a range of display
10150numbers, as in @code{2-4}.
c906108c
SS
10151
10152@kindex enable display
10153@item enable display @var{dnums}@dots{}
10154Enable display of item numbers @var{dnums}. It becomes effective once
10155again in auto display of its expression, until you specify otherwise.
c9174737
PA
10156Specify the numbers of the displays that you want affected with the
10157command argument @var{dnums}. It can be a single display number, one
10158of the numbers shown in the first field of the @samp{info display}
10159display; or it could be a range of display numbers, as in @code{2-4}.
c906108c
SS
10160
10161@item display
10162Display the current values of the expressions on the list, just as is
10163done when your program stops.
10164
10165@kindex info display
10166@item info display
10167Print the list of expressions previously set up to display
10168automatically, each one with its item number, but without showing the
10169values. This includes disabled expressions, which are marked as such.
10170It also includes expressions which would not be displayed right now
10171because they refer to automatic variables not currently available.
10172@end table
10173
15387254 10174@cindex display disabled out of scope
c906108c
SS
10175If a display expression refers to local variables, then it does not make
10176sense outside the lexical context for which it was set up. Such an
10177expression is disabled when execution enters a context where one of its
10178variables is not defined. For example, if you give the command
10179@code{display last_char} while inside a function with an argument
10180@code{last_char}, @value{GDBN} displays this argument while your program
10181continues to stop inside that function. When it stops elsewhere---where
10182there is no variable @code{last_char}---the display is disabled
10183automatically. The next time your program stops where @code{last_char}
10184is meaningful, you can enable the display expression once again.
10185
6d2ebf8b 10186@node Print Settings
79a6e687 10187@section Print Settings
c906108c
SS
10188
10189@cindex format options
10190@cindex print settings
10191@value{GDBN} provides the following ways to control how arrays, structures,
10192and symbols are printed.
10193
10194@noindent
10195These settings are useful for debugging programs in any language:
10196
10197@table @code
4644b6e3 10198@kindex set print
c906108c
SS
10199@item set print address
10200@itemx set print address on
4644b6e3 10201@cindex print/don't print memory addresses
c906108c
SS
10202@value{GDBN} prints memory addresses showing the location of stack
10203traces, structure values, pointer values, breakpoints, and so forth,
10204even when it also displays the contents of those addresses. The default
10205is @code{on}. For example, this is what a stack frame display looks like with
10206@code{set print address on}:
10207
10208@smallexample
10209@group
10210(@value{GDBP}) f
10211#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
10212 at input.c:530
10213530 if (lquote != def_lquote)
10214@end group
10215@end smallexample
10216
10217@item set print address off
10218Do not print addresses when displaying their contents. For example,
10219this is the same stack frame displayed with @code{set print address off}:
10220
10221@smallexample
10222@group
10223(@value{GDBP}) set print addr off
10224(@value{GDBP}) f
10225#0 set_quotes (lq="<<", rq=">>") at input.c:530
10226530 if (lquote != def_lquote)
10227@end group
10228@end smallexample
10229
10230You can use @samp{set print address off} to eliminate all machine
10231dependent displays from the @value{GDBN} interface. For example, with
10232@code{print address off}, you should get the same text for backtraces on
10233all machines---whether or not they involve pointer arguments.
10234
4644b6e3 10235@kindex show print
c906108c
SS
10236@item show print address
10237Show whether or not addresses are to be printed.
10238@end table
10239
10240When @value{GDBN} prints a symbolic address, it normally prints the
10241closest earlier symbol plus an offset. If that symbol does not uniquely
10242identify the address (for example, it is a name whose scope is a single
10243source file), you may need to clarify. One way to do this is with
10244@code{info line}, for example @samp{info line *0x4537}. Alternately,
10245you can set @value{GDBN} to print the source file and line number when
10246it prints a symbolic address:
10247
10248@table @code
c906108c 10249@item set print symbol-filename on
9c16f35a
EZ
10250@cindex source file and line of a symbol
10251@cindex symbol, source file and line
c906108c
SS
10252Tell @value{GDBN} to print the source file name and line number of a
10253symbol in the symbolic form of an address.
10254
10255@item set print symbol-filename off
10256Do not print source file name and line number of a symbol. This is the
10257default.
10258
c906108c
SS
10259@item show print symbol-filename
10260Show whether or not @value{GDBN} will print the source file name and
10261line number of a symbol in the symbolic form of an address.
10262@end table
10263
10264Another situation where it is helpful to show symbol filenames and line
10265numbers is when disassembling code; @value{GDBN} shows you the line
10266number and source file that corresponds to each instruction.
10267
10268Also, you may wish to see the symbolic form only if the address being
10269printed is reasonably close to the closest earlier symbol:
10270
10271@table @code
c906108c 10272@item set print max-symbolic-offset @var{max-offset}
f81d1120 10273@itemx set print max-symbolic-offset unlimited
4644b6e3 10274@cindex maximum value for offset of closest symbol
c906108c
SS
10275Tell @value{GDBN} to only display the symbolic form of an address if the
10276offset between the closest earlier symbol and the address is less than
f81d1120
PA
10277@var{max-offset}. The default is @code{unlimited}, which tells @value{GDBN}
10278to always print the symbolic form of an address if any symbol precedes
10279it. Zero is equivalent to @code{unlimited}.
c906108c 10280
c906108c
SS
10281@item show print max-symbolic-offset
10282Ask how large the maximum offset is that @value{GDBN} prints in a
10283symbolic address.
10284@end table
10285
10286@cindex wild pointer, interpreting
10287@cindex pointer, finding referent
10288If you have a pointer and you are not sure where it points, try
10289@samp{set print symbol-filename on}. Then you can determine the name
10290and source file location of the variable where it points, using
10291@samp{p/a @var{pointer}}. This interprets the address in symbolic form.
10292For example, here @value{GDBN} shows that a variable @code{ptt} points
10293at another variable @code{t}, defined in @file{hi2.c}:
10294
474c8240 10295@smallexample
c906108c
SS
10296(@value{GDBP}) set print symbol-filename on
10297(@value{GDBP}) p/a ptt
10298$4 = 0xe008 <t in hi2.c>
474c8240 10299@end smallexample
c906108c
SS
10300
10301@quotation
10302@emph{Warning:} For pointers that point to a local variable, @samp{p/a}
10303does not show the symbol name and filename of the referent, even with
10304the appropriate @code{set print} options turned on.
10305@end quotation
10306
9cb709b6
TT
10307You can also enable @samp{/a}-like formatting all the time using
10308@samp{set print symbol on}:
10309
10310@table @code
10311@item set print symbol on
10312Tell @value{GDBN} to print the symbol corresponding to an address, if
10313one exists.
10314
10315@item set print symbol off
10316Tell @value{GDBN} not to print the symbol corresponding to an
10317address. In this mode, @value{GDBN} will still print the symbol
10318corresponding to pointers to functions. This is the default.
10319
10320@item show print symbol
10321Show whether @value{GDBN} will display the symbol corresponding to an
10322address.
10323@end table
10324
c906108c
SS
10325Other settings control how different kinds of objects are printed:
10326
10327@table @code
c906108c
SS
10328@item set print array
10329@itemx set print array on
4644b6e3 10330@cindex pretty print arrays
c906108c
SS
10331Pretty print arrays. This format is more convenient to read,
10332but uses more space. The default is off.
10333
10334@item set print array off
10335Return to compressed format for arrays.
10336
c906108c
SS
10337@item show print array
10338Show whether compressed or pretty format is selected for displaying
10339arrays.
10340
3c9c013a
JB
10341@cindex print array indexes
10342@item set print array-indexes
10343@itemx set print array-indexes on
10344Print the index of each element when displaying arrays. May be more
10345convenient to locate a given element in the array or quickly find the
10346index of a given element in that printed array. The default is off.
10347
10348@item set print array-indexes off
10349Stop printing element indexes when displaying arrays.
10350
10351@item show print array-indexes
10352Show whether the index of each element is printed when displaying
10353arrays.
10354
c906108c 10355@item set print elements @var{number-of-elements}
f81d1120 10356@itemx set print elements unlimited
4644b6e3 10357@cindex number of array elements to print
9c16f35a 10358@cindex limit on number of printed array elements
c906108c
SS
10359Set a limit on how many elements of an array @value{GDBN} will print.
10360If @value{GDBN} is printing a large array, it stops printing after it has
10361printed the number of elements set by the @code{set print elements} command.
10362This limit also applies to the display of strings.
d4f3574e 10363When @value{GDBN} starts, this limit is set to 200.
f81d1120
PA
10364Setting @var{number-of-elements} to @code{unlimited} or zero means
10365that the number of elements to print is unlimited.
c906108c 10366
c906108c
SS
10367@item show print elements
10368Display the number of elements of a large array that @value{GDBN} will print.
10369If the number is 0, then the printing is unlimited.
10370
b4740add 10371@item set print frame-arguments @var{value}
a0381d3a 10372@kindex set print frame-arguments
b4740add
JB
10373@cindex printing frame argument values
10374@cindex print all frame argument values
10375@cindex print frame argument values for scalars only
10376@cindex do not print frame argument values
10377This command allows to control how the values of arguments are printed
10378when the debugger prints a frame (@pxref{Frames}). The possible
10379values are:
10380
10381@table @code
10382@item all
4f5376b2 10383The values of all arguments are printed.
b4740add
JB
10384
10385@item scalars
10386Print the value of an argument only if it is a scalar. The value of more
10387complex arguments such as arrays, structures, unions, etc, is replaced
4f5376b2
JB
10388by @code{@dots{}}. This is the default. Here is an example where
10389only scalar arguments are shown:
b4740add
JB
10390
10391@smallexample
10392#1 0x08048361 in call_me (i=3, s=@dots{}, ss=0xbf8d508c, u=@dots{}, e=green)
10393 at frame-args.c:23
10394@end smallexample
10395
10396@item none
10397None of the argument values are printed. Instead, the value of each argument
10398is replaced by @code{@dots{}}. In this case, the example above now becomes:
10399
10400@smallexample
10401#1 0x08048361 in call_me (i=@dots{}, s=@dots{}, ss=@dots{}, u=@dots{}, e=@dots{})
10402 at frame-args.c:23
10403@end smallexample
10404@end table
10405
4f5376b2
JB
10406By default, only scalar arguments are printed. This command can be used
10407to configure the debugger to print the value of all arguments, regardless
10408of their type. However, it is often advantageous to not print the value
10409of more complex parameters. For instance, it reduces the amount of
10410information printed in each frame, making the backtrace more readable.
10411Also, it improves performance when displaying Ada frames, because
10412the computation of large arguments can sometimes be CPU-intensive,
10413especially in large applications. Setting @code{print frame-arguments}
10414to @code{scalars} (the default) or @code{none} avoids this computation,
10415thus speeding up the display of each Ada frame.
b4740add
JB
10416
10417@item show print frame-arguments
10418Show how the value of arguments should be displayed when printing a frame.
10419
e7045703
DE
10420@item set print raw frame-arguments on
10421Print frame arguments in raw, non pretty-printed, form.
10422
10423@item set print raw frame-arguments off
10424Print frame arguments in pretty-printed form, if there is a pretty-printer
10425for the value (@pxref{Pretty Printing}),
10426otherwise print the value in raw form.
10427This is the default.
10428
10429@item show print raw frame-arguments
10430Show whether to print frame arguments in raw form.
10431
36b11add 10432@anchor{set print entry-values}
e18b2753
JK
10433@item set print entry-values @var{value}
10434@kindex set print entry-values
10435Set printing of frame argument values at function entry. In some cases
10436@value{GDBN} can determine the value of function argument which was passed by
10437the function caller, even if the value was modified inside the called function
10438and therefore is different. With optimized code, the current value could be
10439unavailable, but the entry value may still be known.
10440
10441The default value is @code{default} (see below for its description). Older
10442@value{GDBN} behaved as with the setting @code{no}. Compilers not supporting
10443this feature will behave in the @code{default} setting the same way as with the
10444@code{no} setting.
10445
10446This functionality is currently supported only by DWARF 2 debugging format and
216f72a1 10447the compiler has to produce @samp{DW_TAG_call_site} tags. With
e18b2753
JK
10448@value{NGCC}, you need to specify @option{-O -g} during compilation, to get
10449this information.
10450
10451The @var{value} parameter can be one of the following:
10452
10453@table @code
10454@item no
10455Print only actual parameter values, never print values from function entry
10456point.
10457@smallexample
10458#0 equal (val=5)
10459#0 different (val=6)
10460#0 lost (val=<optimized out>)
10461#0 born (val=10)
10462#0 invalid (val=<optimized out>)
10463@end smallexample
10464
10465@item only
10466Print only parameter values from function entry point. The actual parameter
10467values are never printed.
10468@smallexample
10469#0 equal (val@@entry=5)
10470#0 different (val@@entry=5)
10471#0 lost (val@@entry=5)
10472#0 born (val@@entry=<optimized out>)
10473#0 invalid (val@@entry=<optimized out>)
10474@end smallexample
10475
10476@item preferred
10477Print only parameter values from function entry point. If value from function
10478entry point is not known while the actual value is known, print the actual
10479value for such parameter.
10480@smallexample
10481#0 equal (val@@entry=5)
10482#0 different (val@@entry=5)
10483#0 lost (val@@entry=5)
10484#0 born (val=10)
10485#0 invalid (val@@entry=<optimized out>)
10486@end smallexample
10487
10488@item if-needed
10489Print actual parameter values. If actual parameter value is not known while
10490value from function entry point is known, print the entry point value for such
10491parameter.
10492@smallexample
10493#0 equal (val=5)
10494#0 different (val=6)
10495#0 lost (val@@entry=5)
10496#0 born (val=10)
10497#0 invalid (val=<optimized out>)
10498@end smallexample
10499
10500@item both
10501Always print both the actual parameter value and its value from function entry
10502point, even if values of one or both are not available due to compiler
10503optimizations.
10504@smallexample
10505#0 equal (val=5, val@@entry=5)
10506#0 different (val=6, val@@entry=5)
10507#0 lost (val=<optimized out>, val@@entry=5)
10508#0 born (val=10, val@@entry=<optimized out>)
10509#0 invalid (val=<optimized out>, val@@entry=<optimized out>)
10510@end smallexample
10511
10512@item compact
10513Print the actual parameter value if it is known and also its value from
10514function entry point if it is known. If neither is known, print for the actual
10515value @code{<optimized out>}. If not in MI mode (@pxref{GDB/MI}) and if both
10516values are known and identical, print the shortened
10517@code{param=param@@entry=VALUE} notation.
10518@smallexample
10519#0 equal (val=val@@entry=5)
10520#0 different (val=6, val@@entry=5)
10521#0 lost (val@@entry=5)
10522#0 born (val=10)
10523#0 invalid (val=<optimized out>)
10524@end smallexample
10525
10526@item default
10527Always print the actual parameter value. Print also its value from function
10528entry point, but only if it is known. If not in MI mode (@pxref{GDB/MI}) and
10529if both values are known and identical, print the shortened
10530@code{param=param@@entry=VALUE} notation.
10531@smallexample
10532#0 equal (val=val@@entry=5)
10533#0 different (val=6, val@@entry=5)
10534#0 lost (val=<optimized out>, val@@entry=5)
10535#0 born (val=10)
10536#0 invalid (val=<optimized out>)
10537@end smallexample
10538@end table
10539
10540For analysis messages on possible failures of frame argument values at function
10541entry resolution see @ref{set debug entry-values}.
10542
10543@item show print entry-values
10544Show the method being used for printing of frame argument values at function
10545entry.
10546
f81d1120
PA
10547@item set print repeats @var{number-of-repeats}
10548@itemx set print repeats unlimited
9c16f35a
EZ
10549@cindex repeated array elements
10550Set the threshold for suppressing display of repeated array
d3e8051b 10551elements. When the number of consecutive identical elements of an
9c16f35a
EZ
10552array exceeds the threshold, @value{GDBN} prints the string
10553@code{"<repeats @var{n} times>"}, where @var{n} is the number of
10554identical repetitions, instead of displaying the identical elements
f81d1120
PA
10555themselves. Setting the threshold to @code{unlimited} or zero will
10556cause all elements to be individually printed. The default threshold
10557is 10.
9c16f35a
EZ
10558
10559@item show print repeats
10560Display the current threshold for printing repeated identical
10561elements.
10562
c906108c 10563@item set print null-stop
4644b6e3 10564@cindex @sc{null} elements in arrays
c906108c 10565Cause @value{GDBN} to stop printing the characters of an array when the first
d4f3574e 10566@sc{null} is encountered. This is useful when large arrays actually
c906108c 10567contain only short strings.
d4f3574e 10568The default is off.
c906108c 10569
9c16f35a
EZ
10570@item show print null-stop
10571Show whether @value{GDBN} stops printing an array on the first
10572@sc{null} character.
10573
c906108c 10574@item set print pretty on
9c16f35a
EZ
10575@cindex print structures in indented form
10576@cindex indentation in structure display
5d161b24 10577Cause @value{GDBN} to print structures in an indented format with one member
c906108c
SS
10578per line, like this:
10579
10580@smallexample
10581@group
10582$1 = @{
10583 next = 0x0,
10584 flags = @{
10585 sweet = 1,
10586 sour = 1
10587 @},
10588 meat = 0x54 "Pork"
10589@}
10590@end group
10591@end smallexample
10592
10593@item set print pretty off
10594Cause @value{GDBN} to print structures in a compact format, like this:
10595
10596@smallexample
10597@group
10598$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \
10599meat = 0x54 "Pork"@}
10600@end group
10601@end smallexample
10602
10603@noindent
10604This is the default format.
10605
c906108c
SS
10606@item show print pretty
10607Show which format @value{GDBN} is using to print structures.
10608
c906108c 10609@item set print sevenbit-strings on
4644b6e3
EZ
10610@cindex eight-bit characters in strings
10611@cindex octal escapes in strings
c906108c
SS
10612Print using only seven-bit characters; if this option is set,
10613@value{GDBN} displays any eight-bit characters (in strings or
10614character values) using the notation @code{\}@var{nnn}. This setting is
10615best if you are working in English (@sc{ascii}) and you use the
10616high-order bit of characters as a marker or ``meta'' bit.
10617
10618@item set print sevenbit-strings off
10619Print full eight-bit characters. This allows the use of more
10620international character sets, and is the default.
10621
c906108c
SS
10622@item show print sevenbit-strings
10623Show whether or not @value{GDBN} is printing only seven-bit characters.
10624
c906108c 10625@item set print union on
4644b6e3 10626@cindex unions in structures, printing
9c16f35a
EZ
10627Tell @value{GDBN} to print unions which are contained in structures
10628and other unions. This is the default setting.
c906108c
SS
10629
10630@item set print union off
9c16f35a
EZ
10631Tell @value{GDBN} not to print unions which are contained in
10632structures and other unions. @value{GDBN} will print @code{"@{...@}"}
10633instead.
c906108c 10634
c906108c
SS
10635@item show print union
10636Ask @value{GDBN} whether or not it will print unions which are contained in
9c16f35a 10637structures and other unions.
c906108c
SS
10638
10639For example, given the declarations
10640
10641@smallexample
10642typedef enum @{Tree, Bug@} Species;
10643typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
5d161b24 10644typedef enum @{Caterpillar, Cocoon, Butterfly@}
c906108c
SS
10645 Bug_forms;
10646
10647struct thing @{
10648 Species it;
10649 union @{
10650 Tree_forms tree;
10651 Bug_forms bug;
10652 @} form;
10653@};
10654
10655struct thing foo = @{Tree, @{Acorn@}@};
10656@end smallexample
10657
10658@noindent
10659with @code{set print union on} in effect @samp{p foo} would print
10660
10661@smallexample
10662$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
10663@end smallexample
10664
10665@noindent
10666and with @code{set print union off} in effect it would print
10667
10668@smallexample
10669$1 = @{it = Tree, form = @{...@}@}
10670@end smallexample
9c16f35a
EZ
10671
10672@noindent
10673@code{set print union} affects programs written in C-like languages
10674and in Pascal.
c906108c
SS
10675@end table
10676
c906108c
SS
10677@need 1000
10678@noindent
b37052ae 10679These settings are of interest when debugging C@t{++} programs:
c906108c
SS
10680
10681@table @code
4644b6e3 10682@cindex demangling C@t{++} names
c906108c
SS
10683@item set print demangle
10684@itemx set print demangle on
b37052ae 10685Print C@t{++} names in their source form rather than in the encoded
c906108c 10686(``mangled'') form passed to the assembler and linker for type-safe
d4f3574e 10687linkage. The default is on.
c906108c 10688
c906108c 10689@item show print demangle
b37052ae 10690Show whether C@t{++} names are printed in mangled or demangled form.
c906108c 10691
c906108c
SS
10692@item set print asm-demangle
10693@itemx set print asm-demangle on
b37052ae 10694Print C@t{++} names in their source form rather than their mangled form, even
c906108c
SS
10695in assembler code printouts such as instruction disassemblies.
10696The default is off.
10697
c906108c 10698@item show print asm-demangle
b37052ae 10699Show whether C@t{++} names in assembly listings are printed in mangled
c906108c
SS
10700or demangled form.
10701
b37052ae
EZ
10702@cindex C@t{++} symbol decoding style
10703@cindex symbol decoding style, C@t{++}
a8f24a35 10704@kindex set demangle-style
c906108c 10705@item set demangle-style @var{style}
041be526
SM
10706Choose among several encoding schemes used by different compilers to represent
10707C@t{++} names. If you omit @var{style}, you will see a list of possible
10708formats. The default value is @var{auto}, which lets @value{GDBN} choose a
10709decoding style by inspecting your program.
c906108c 10710
c906108c 10711@item show demangle-style
b37052ae 10712Display the encoding style currently in use for decoding C@t{++} symbols.
c906108c 10713
c906108c
SS
10714@item set print object
10715@itemx set print object on
4644b6e3 10716@cindex derived type of an object, printing
9c16f35a 10717@cindex display derived types
c906108c
SS
10718When displaying a pointer to an object, identify the @emph{actual}
10719(derived) type of the object rather than the @emph{declared} type, using
625c0d47
TT
10720the virtual function table. Note that the virtual function table is
10721required---this feature can only work for objects that have run-time
10722type identification; a single virtual method in the object's declared
8264ba82
AG
10723type is sufficient. Note that this setting is also taken into account when
10724working with variable objects via MI (@pxref{GDB/MI}).
c906108c
SS
10725
10726@item set print object off
10727Display only the declared type of objects, without reference to the
10728virtual function table. This is the default setting.
10729
c906108c
SS
10730@item show print object
10731Show whether actual, or declared, object types are displayed.
10732
c906108c
SS
10733@item set print static-members
10734@itemx set print static-members on
4644b6e3 10735@cindex static members of C@t{++} objects
b37052ae 10736Print static members when displaying a C@t{++} object. The default is on.
c906108c
SS
10737
10738@item set print static-members off
b37052ae 10739Do not print static members when displaying a C@t{++} object.
c906108c 10740
c906108c 10741@item show print static-members
9c16f35a
EZ
10742Show whether C@t{++} static members are printed or not.
10743
10744@item set print pascal_static-members
10745@itemx set print pascal_static-members on
d3e8051b
EZ
10746@cindex static members of Pascal objects
10747@cindex Pascal objects, static members display
9c16f35a
EZ
10748Print static members when displaying a Pascal object. The default is on.
10749
10750@item set print pascal_static-members off
10751Do not print static members when displaying a Pascal object.
10752
10753@item show print pascal_static-members
10754Show whether Pascal static members are printed or not.
c906108c
SS
10755
10756@c These don't work with HP ANSI C++ yet.
c906108c
SS
10757@item set print vtbl
10758@itemx set print vtbl on
4644b6e3 10759@cindex pretty print C@t{++} virtual function tables
9c16f35a
EZ
10760@cindex virtual functions (C@t{++}) display
10761@cindex VTBL display
b37052ae 10762Pretty print C@t{++} virtual function tables. The default is off.
c906108c 10763(The @code{vtbl} commands do not work on programs compiled with the HP
b37052ae 10764ANSI C@t{++} compiler (@code{aCC}).)
c906108c
SS
10765
10766@item set print vtbl off
b37052ae 10767Do not pretty print C@t{++} virtual function tables.
c906108c 10768
c906108c 10769@item show print vtbl
b37052ae 10770Show whether C@t{++} virtual function tables are pretty printed, or not.
c906108c 10771@end table
c906108c 10772
4c374409
JK
10773@node Pretty Printing
10774@section Pretty Printing
10775
10776@value{GDBN} provides a mechanism to allow pretty-printing of values using
10777Python code. It greatly simplifies the display of complex objects. This
10778mechanism works for both MI and the CLI.
10779
7b51bc51
DE
10780@menu
10781* Pretty-Printer Introduction:: Introduction to pretty-printers
10782* Pretty-Printer Example:: An example pretty-printer
10783* Pretty-Printer Commands:: Pretty-printer commands
10784@end menu
10785
10786@node Pretty-Printer Introduction
10787@subsection Pretty-Printer Introduction
10788
10789When @value{GDBN} prints a value, it first sees if there is a pretty-printer
10790registered for the value. If there is then @value{GDBN} invokes the
10791pretty-printer to print the value. Otherwise the value is printed normally.
10792
10793Pretty-printers are normally named. This makes them easy to manage.
10794The @samp{info pretty-printer} command will list all the installed
10795pretty-printers with their names.
10796If a pretty-printer can handle multiple data types, then its
10797@dfn{subprinters} are the printers for the individual data types.
10798Each such subprinter has its own name.
4e04c971 10799The format of the name is @var{printer-name};@var{subprinter-name}.
7b51bc51
DE
10800
10801Pretty-printers are installed by @dfn{registering} them with @value{GDBN}.
10802Typically they are automatically loaded and registered when the corresponding
10803debug information is loaded, thus making them available without having to
10804do anything special.
10805
10806There are three places where a pretty-printer can be registered.
10807
10808@itemize @bullet
10809@item
10810Pretty-printers registered globally are available when debugging
10811all inferiors.
10812
10813@item
10814Pretty-printers registered with a program space are available only
10815when debugging that program.
10816@xref{Progspaces In Python}, for more details on program spaces in Python.
10817
10818@item
10819Pretty-printers registered with an objfile are loaded and unloaded
10820with the corresponding objfile (e.g., shared library).
10821@xref{Objfiles In Python}, for more details on objfiles in Python.
10822@end itemize
10823
10824@xref{Selecting Pretty-Printers}, for further information on how
10825pretty-printers are selected,
10826
10827@xref{Writing a Pretty-Printer}, for implementing pretty printers
10828for new types.
10829
10830@node Pretty-Printer Example
10831@subsection Pretty-Printer Example
10832
10833Here is how a C@t{++} @code{std::string} looks without a pretty-printer:
4c374409
JK
10834
10835@smallexample
10836(@value{GDBP}) print s
10837$1 = @{
10838 static npos = 4294967295,
10839 _M_dataplus = @{
10840 <std::allocator<char>> = @{
10841 <__gnu_cxx::new_allocator<char>> = @{
10842 <No data fields>@}, <No data fields>
10843 @},
10844 members of std::basic_string<char, std::char_traits<char>,
10845 std::allocator<char> >::_Alloc_hider:
10846 _M_p = 0x804a014 "abcd"
10847 @}
10848@}
10849@end smallexample
10850
10851With a pretty-printer for @code{std::string} only the contents are printed:
10852
10853@smallexample
10854(@value{GDBP}) print s
10855$2 = "abcd"
10856@end smallexample
10857
7b51bc51
DE
10858@node Pretty-Printer Commands
10859@subsection Pretty-Printer Commands
10860@cindex pretty-printer commands
10861
10862@table @code
10863@kindex info pretty-printer
10864@item info pretty-printer [@var{object-regexp} [@var{name-regexp}]]
10865Print the list of installed pretty-printers.
10866This includes disabled pretty-printers, which are marked as such.
10867
10868@var{object-regexp} is a regular expression matching the objects
10869whose pretty-printers to list.
10870Objects can be @code{global}, the program space's file
10871(@pxref{Progspaces In Python}),
10872and the object files within that program space (@pxref{Objfiles In Python}).
10873@xref{Selecting Pretty-Printers}, for details on how @value{GDBN}
10874looks up a printer from these three objects.
10875
10876@var{name-regexp} is a regular expression matching the name of the printers
10877to list.
10878
10879@kindex disable pretty-printer
10880@item disable pretty-printer [@var{object-regexp} [@var{name-regexp}]]
10881Disable pretty-printers matching @var{object-regexp} and @var{name-regexp}.
10882A disabled pretty-printer is not forgotten, it may be enabled again later.
10883
10884@kindex enable pretty-printer
10885@item enable pretty-printer [@var{object-regexp} [@var{name-regexp}]]
10886Enable pretty-printers matching @var{object-regexp} and @var{name-regexp}.
10887@end table
10888
10889Example:
10890
10891Suppose we have three pretty-printers installed: one from library1.so
10892named @code{foo} that prints objects of type @code{foo}, and
10893another from library2.so named @code{bar} that prints two types of objects,
10894@code{bar1} and @code{bar2}.
10895
10896@smallexample
10897(gdb) info pretty-printer
10898library1.so:
10899 foo
10900library2.so:
10901 bar
10902 bar1
10903 bar2
10904(gdb) info pretty-printer library2
10905library2.so:
10906 bar
10907 bar1
10908 bar2
10909(gdb) disable pretty-printer library1
109101 printer disabled
109112 of 3 printers enabled
10912(gdb) info pretty-printer
10913library1.so:
10914 foo [disabled]
10915library2.so:
10916 bar
10917 bar1
10918 bar2
088a96da 10919(gdb) disable pretty-printer library2 bar;bar1
7b51bc51
DE
109201 printer disabled
109211 of 3 printers enabled
10922(gdb) info pretty-printer library2
10923library1.so:
10924 foo [disabled]
10925library2.so:
10926 bar
10927 bar1 [disabled]
10928 bar2
10929(gdb) disable pretty-printer library2 bar
109301 printer disabled
109310 of 3 printers enabled
10932(gdb) info pretty-printer library2
10933library1.so:
10934 foo [disabled]
10935library2.so:
10936 bar [disabled]
10937 bar1 [disabled]
10938 bar2
10939@end smallexample
10940
10941Note that for @code{bar} the entire printer can be disabled,
10942as can each individual subprinter.
4c374409 10943
6d2ebf8b 10944@node Value History
79a6e687 10945@section Value History
c906108c
SS
10946
10947@cindex value history
9c16f35a 10948@cindex history of values printed by @value{GDBN}
5d161b24
DB
10949Values printed by the @code{print} command are saved in the @value{GDBN}
10950@dfn{value history}. This allows you to refer to them in other expressions.
10951Values are kept until the symbol table is re-read or discarded
10952(for example with the @code{file} or @code{symbol-file} commands).
10953When the symbol table changes, the value history is discarded,
10954since the values may contain pointers back to the types defined in the
c906108c
SS
10955symbol table.
10956
10957@cindex @code{$}
10958@cindex @code{$$}
10959@cindex history number
10960The values printed are given @dfn{history numbers} by which you can
10961refer to them. These are successive integers starting with one.
10962@code{print} shows you the history number assigned to a value by
10963printing @samp{$@var{num} = } before the value; here @var{num} is the
10964history number.
10965
10966To refer to any previous value, use @samp{$} followed by the value's
10967history number. The way @code{print} labels its output is designed to
10968remind you of this. Just @code{$} refers to the most recent value in
10969the history, and @code{$$} refers to the value before that.
10970@code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2}
10971is the value just prior to @code{$$}, @code{$$1} is equivalent to
10972@code{$$}, and @code{$$0} is equivalent to @code{$}.
10973
10974For example, suppose you have just printed a pointer to a structure and
10975want to see the contents of the structure. It suffices to type
10976
474c8240 10977@smallexample
c906108c 10978p *$
474c8240 10979@end smallexample
c906108c
SS
10980
10981If you have a chain of structures where the component @code{next} points
10982to the next one, you can print the contents of the next one with this:
10983
474c8240 10984@smallexample
c906108c 10985p *$.next
474c8240 10986@end smallexample
c906108c
SS
10987
10988@noindent
10989You can print successive links in the chain by repeating this
10990command---which you can do by just typing @key{RET}.
10991
10992Note that the history records values, not expressions. If the value of
10993@code{x} is 4 and you type these commands:
10994
474c8240 10995@smallexample
c906108c
SS
10996print x
10997set x=5
474c8240 10998@end smallexample
c906108c
SS
10999
11000@noindent
11001then the value recorded in the value history by the @code{print} command
11002remains 4 even though the value of @code{x} has changed.
11003
11004@table @code
11005@kindex show values
11006@item show values
11007Print the last ten values in the value history, with their item numbers.
11008This is like @samp{p@ $$9} repeated ten times, except that @code{show
11009values} does not change the history.
11010
11011@item show values @var{n}
11012Print ten history values centered on history item number @var{n}.
11013
11014@item show values +
11015Print ten history values just after the values last printed. If no more
11016values are available, @code{show values +} produces no display.
11017@end table
11018
11019Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
11020same effect as @samp{show values +}.
11021
6d2ebf8b 11022@node Convenience Vars
79a6e687 11023@section Convenience Variables
c906108c
SS
11024
11025@cindex convenience variables
9c16f35a 11026@cindex user-defined variables
c906108c
SS
11027@value{GDBN} provides @dfn{convenience variables} that you can use within
11028@value{GDBN} to hold on to a value and refer to it later. These variables
11029exist entirely within @value{GDBN}; they are not part of your program, and
11030setting a convenience variable has no direct effect on further execution
11031of your program. That is why you can use them freely.
11032
11033Convenience variables are prefixed with @samp{$}. Any name preceded by
11034@samp{$} can be used for a convenience variable, unless it is one of
d4f3574e 11035the predefined machine-specific register names (@pxref{Registers, ,Registers}).
c906108c 11036(Value history references, in contrast, are @emph{numbers} preceded
79a6e687 11037by @samp{$}. @xref{Value History, ,Value History}.)
c906108c
SS
11038
11039You can save a value in a convenience variable with an assignment
11040expression, just as you would set a variable in your program.
11041For example:
11042
474c8240 11043@smallexample
c906108c 11044set $foo = *object_ptr
474c8240 11045@end smallexample
c906108c
SS
11046
11047@noindent
11048would save in @code{$foo} the value contained in the object pointed to by
11049@code{object_ptr}.
11050
11051Using a convenience variable for the first time creates it, but its
11052value is @code{void} until you assign a new value. You can alter the
11053value with another assignment at any time.
11054
11055Convenience variables have no fixed types. You can assign a convenience
11056variable any type of value, including structures and arrays, even if
11057that variable already has a value of a different type. The convenience
11058variable, when used as an expression, has the type of its current value.
11059
11060@table @code
11061@kindex show convenience
f47f77df 11062@cindex show all user variables and functions
c906108c 11063@item show convenience
f47f77df
DE
11064Print a list of convenience variables used so far, and their values,
11065as well as a list of the convenience functions.
d4f3574e 11066Abbreviated @code{show conv}.
53e5f3cf
AS
11067
11068@kindex init-if-undefined
11069@cindex convenience variables, initializing
11070@item init-if-undefined $@var{variable} = @var{expression}
11071Set a convenience variable if it has not already been set. This is useful
11072for user-defined commands that keep some state. It is similar, in concept,
11073to using local static variables with initializers in C (except that
11074convenience variables are global). It can also be used to allow users to
11075override default values used in a command script.
11076
11077If the variable is already defined then the expression is not evaluated so
11078any side-effects do not occur.
c906108c
SS
11079@end table
11080
11081One of the ways to use a convenience variable is as a counter to be
11082incremented or a pointer to be advanced. For example, to print
11083a field from successive elements of an array of structures:
11084
474c8240 11085@smallexample
c906108c
SS
11086set $i = 0
11087print bar[$i++]->contents
474c8240 11088@end smallexample
c906108c 11089
d4f3574e
SS
11090@noindent
11091Repeat that command by typing @key{RET}.
c906108c
SS
11092
11093Some convenience variables are created automatically by @value{GDBN} and given
11094values likely to be useful.
11095
11096@table @code
41afff9a 11097@vindex $_@r{, convenience variable}
c906108c
SS
11098@item $_
11099The variable @code{$_} is automatically set by the @code{x} command to
79a6e687 11100the last address examined (@pxref{Memory, ,Examining Memory}). Other
c906108c
SS
11101commands which provide a default address for @code{x} to examine also
11102set @code{$_} to that address; these commands include @code{info line}
11103and @code{info breakpoint}. The type of @code{$_} is @code{void *}
11104except when set by the @code{x} command, in which case it is a pointer
11105to the type of @code{$__}.
11106
41afff9a 11107@vindex $__@r{, convenience variable}
c906108c
SS
11108@item $__
11109The variable @code{$__} is automatically set by the @code{x} command
11110to the value found in the last address examined. Its type is chosen
11111to match the format in which the data was printed.
11112
11113@item $_exitcode
41afff9a 11114@vindex $_exitcode@r{, convenience variable}
0c557179
SDJ
11115When the program being debugged terminates normally, @value{GDBN}
11116automatically sets this variable to the exit code of the program, and
11117resets @code{$_exitsignal} to @code{void}.
11118
11119@item $_exitsignal
11120@vindex $_exitsignal@r{, convenience variable}
11121When the program being debugged dies due to an uncaught signal,
11122@value{GDBN} automatically sets this variable to that signal's number,
11123and resets @code{$_exitcode} to @code{void}.
11124
11125To distinguish between whether the program being debugged has exited
11126(i.e., @code{$_exitcode} is not @code{void}) or signalled (i.e.,
11127@code{$_exitsignal} is not @code{void}), the convenience function
11128@code{$_isvoid} can be used (@pxref{Convenience Funs,, Convenience
11129Functions}). For example, considering the following source code:
11130
11131@smallexample
11132#include <signal.h>
11133
11134int
11135main (int argc, char *argv[])
11136@{
11137 raise (SIGALRM);
11138 return 0;
11139@}
11140@end smallexample
11141
11142A valid way of telling whether the program being debugged has exited
11143or signalled would be:
11144
11145@smallexample
11146(@value{GDBP}) define has_exited_or_signalled
11147Type commands for definition of ``has_exited_or_signalled''.
11148End with a line saying just ``end''.
11149>if $_isvoid ($_exitsignal)
11150 >echo The program has exited\n
11151 >else
11152 >echo The program has signalled\n
11153 >end
11154>end
11155(@value{GDBP}) run
11156Starting program:
11157
11158Program terminated with signal SIGALRM, Alarm clock.
11159The program no longer exists.
11160(@value{GDBP}) has_exited_or_signalled
11161The program has signalled
11162@end smallexample
11163
11164As can be seen, @value{GDBN} correctly informs that the program being
11165debugged has signalled, since it calls @code{raise} and raises a
11166@code{SIGALRM} signal. If the program being debugged had not called
11167@code{raise}, then @value{GDBN} would report a normal exit:
11168
11169@smallexample
11170(@value{GDBP}) has_exited_or_signalled
11171The program has exited
11172@end smallexample
4aa995e1 11173
72f1fe8a
TT
11174@item $_exception
11175The variable @code{$_exception} is set to the exception object being
11176thrown at an exception-related catchpoint. @xref{Set Catchpoints}.
11177
62e5f89c
SDJ
11178@item $_probe_argc
11179@itemx $_probe_arg0@dots{}$_probe_arg11
11180Arguments to a static probe. @xref{Static Probe Points}.
11181
0fb4aa4b
PA
11182@item $_sdata
11183@vindex $_sdata@r{, inspect, convenience variable}
11184The variable @code{$_sdata} contains extra collected static tracepoint
11185data. @xref{Tracepoint Actions,,Tracepoint Action Lists}. Note that
11186@code{$_sdata} could be empty, if not inspecting a trace buffer, or
11187if extra static tracepoint data has not been collected.
11188
4aa995e1
PA
11189@item $_siginfo
11190@vindex $_siginfo@r{, convenience variable}
ec7e75e7
PP
11191The variable @code{$_siginfo} contains extra signal information
11192(@pxref{extra signal information}). Note that @code{$_siginfo}
11193could be empty, if the application has not yet received any signals.
11194For example, it will be empty before you execute the @code{run} command.
711e434b
PM
11195
11196@item $_tlb
11197@vindex $_tlb@r{, convenience variable}
11198The variable @code{$_tlb} is automatically set when debugging
11199applications running on MS-Windows in native mode or connected to
7734102d 11200gdbserver that supports the @code{qGetTIBAddr} request.
711e434b
PM
11201@xref{General Query Packets}.
11202This variable contains the address of the thread information block.
11203
e3940304
PA
11204@item $_inferior
11205The number of the current inferior. @xref{Inferiors and
11206Programs, ,Debugging Multiple Inferiors and Programs}.
11207
5d5658a1
PA
11208@item $_thread
11209The thread number of the current thread. @xref{thread numbers}.
11210
663f6d42
PA
11211@item $_gthread
11212The global number of the current thread. @xref{global thread numbers}.
11213
7734102d
EZ
11214@item $_gdb_major
11215@itemx $_gdb_minor
11216@vindex $_gdb_major@r{, convenience variable}
11217@vindex $_gdb_minor@r{, convenience variable}
11218The major and minor version numbers of the running @value{GDBN}.
11219Development snapshots and pretest versions have their minor version
11220incremented by one; thus, @value{GDBN} pretest 9.11.90 will produce
11221the value 12 for @code{$_gdb_minor}. These variables allow you to
11222write scripts that work with different versions of @value{GDBN}
11223without errors caused by features unavailable in some of those
11224versions.
c906108c
SS
11225@end table
11226
a72c3253
DE
11227@node Convenience Funs
11228@section Convenience Functions
11229
bc3b79fd
TJB
11230@cindex convenience functions
11231@value{GDBN} also supplies some @dfn{convenience functions}. These
11232have a syntax similar to convenience variables. A convenience
11233function can be used in an expression just like an ordinary function;
11234however, a convenience function is implemented internally to
11235@value{GDBN}.
11236
a280dbd1
SDJ
11237These functions do not require @value{GDBN} to be configured with
11238@code{Python} support, which means that they are always available.
11239
11240@table @code
11241
11242@item $_isvoid (@var{expr})
11243@findex $_isvoid@r{, convenience function}
11244Return one if the expression @var{expr} is @code{void}. Otherwise it
11245returns zero.
11246
11247A @code{void} expression is an expression where the type of the result
11248is @code{void}. For example, you can examine a convenience variable
11249(see @ref{Convenience Vars,, Convenience Variables}) to check whether
11250it is @code{void}:
11251
11252@smallexample
11253(@value{GDBP}) print $_exitcode
11254$1 = void
11255(@value{GDBP}) print $_isvoid ($_exitcode)
11256$2 = 1
11257(@value{GDBP}) run
11258Starting program: ./a.out
11259[Inferior 1 (process 29572) exited normally]
11260(@value{GDBP}) print $_exitcode
11261$3 = 0
11262(@value{GDBP}) print $_isvoid ($_exitcode)
11263$4 = 0
11264@end smallexample
11265
11266In the example above, we used @code{$_isvoid} to check whether
11267@code{$_exitcode} is @code{void} before and after the execution of the
11268program being debugged. Before the execution there is no exit code to
11269be examined, therefore @code{$_exitcode} is @code{void}. After the
11270execution the program being debugged returned zero, therefore
11271@code{$_exitcode} is zero, which means that it is not @code{void}
11272anymore.
11273
11274The @code{void} expression can also be a call of a function from the
11275program being debugged. For example, given the following function:
11276
11277@smallexample
11278void
11279foo (void)
11280@{
11281@}
11282@end smallexample
11283
11284The result of calling it inside @value{GDBN} is @code{void}:
11285
11286@smallexample
11287(@value{GDBP}) print foo ()
11288$1 = void
11289(@value{GDBP}) print $_isvoid (foo ())
11290$2 = 1
11291(@value{GDBP}) set $v = foo ()
11292(@value{GDBP}) print $v
11293$3 = void
11294(@value{GDBP}) print $_isvoid ($v)
11295$4 = 1
11296@end smallexample
11297
11298@end table
11299
a72c3253
DE
11300These functions require @value{GDBN} to be configured with
11301@code{Python} support.
11302
11303@table @code
11304
11305@item $_memeq(@var{buf1}, @var{buf2}, @var{length})
11306@findex $_memeq@r{, convenience function}
11307Returns one if the @var{length} bytes at the addresses given by
11308@var{buf1} and @var{buf2} are equal.
11309Otherwise it returns zero.
11310
11311@item $_regex(@var{str}, @var{regex})
11312@findex $_regex@r{, convenience function}
11313Returns one if the string @var{str} matches the regular expression
11314@var{regex}. Otherwise it returns zero.
11315The syntax of the regular expression is that specified by @code{Python}'s
11316regular expression support.
11317
11318@item $_streq(@var{str1}, @var{str2})
11319@findex $_streq@r{, convenience function}
11320Returns one if the strings @var{str1} and @var{str2} are equal.
11321Otherwise it returns zero.
11322
11323@item $_strlen(@var{str})
11324@findex $_strlen@r{, convenience function}
11325Returns the length of string @var{str}.
11326
faa42425
DE
11327@item $_caller_is(@var{name}@r{[}, @var{number_of_frames}@r{]})
11328@findex $_caller_is@r{, convenience function}
11329Returns one if the calling function's name is equal to @var{name}.
11330Otherwise it returns zero.
11331
11332If the optional argument @var{number_of_frames} is provided,
11333it is the number of frames up in the stack to look.
11334The default is 1.
11335
11336Example:
11337
11338@smallexample
11339(gdb) backtrace
11340#0 bottom_func ()
11341 at testsuite/gdb.python/py-caller-is.c:21
11342#1 0x00000000004005a0 in middle_func ()
11343 at testsuite/gdb.python/py-caller-is.c:27
11344#2 0x00000000004005ab in top_func ()
11345 at testsuite/gdb.python/py-caller-is.c:33
11346#3 0x00000000004005b6 in main ()
11347 at testsuite/gdb.python/py-caller-is.c:39
11348(gdb) print $_caller_is ("middle_func")
11349$1 = 1
11350(gdb) print $_caller_is ("top_func", 2)
11351$1 = 1
11352@end smallexample
11353
11354@item $_caller_matches(@var{regexp}@r{[}, @var{number_of_frames}@r{]})
11355@findex $_caller_matches@r{, convenience function}
11356Returns one if the calling function's name matches the regular expression
11357@var{regexp}. Otherwise it returns zero.
11358
11359If the optional argument @var{number_of_frames} is provided,
11360it is the number of frames up in the stack to look.
11361The default is 1.
11362
11363@item $_any_caller_is(@var{name}@r{[}, @var{number_of_frames}@r{]})
11364@findex $_any_caller_is@r{, convenience function}
11365Returns one if any calling function's name is equal to @var{name}.
11366Otherwise it returns zero.
11367
11368If the optional argument @var{number_of_frames} is provided,
11369it is the number of frames up in the stack to look.
11370The default is 1.
11371
11372This function differs from @code{$_caller_is} in that this function
11373checks all stack frames from the immediate caller to the frame specified
11374by @var{number_of_frames}, whereas @code{$_caller_is} only checks the
11375frame specified by @var{number_of_frames}.
11376
11377@item $_any_caller_matches(@var{regexp}@r{[}, @var{number_of_frames}@r{]})
11378@findex $_any_caller_matches@r{, convenience function}
11379Returns one if any calling function's name matches the regular expression
11380@var{regexp}. Otherwise it returns zero.
11381
11382If the optional argument @var{number_of_frames} is provided,
11383it is the number of frames up in the stack to look.
11384The default is 1.
11385
11386This function differs from @code{$_caller_matches} in that this function
11387checks all stack frames from the immediate caller to the frame specified
11388by @var{number_of_frames}, whereas @code{$_caller_matches} only checks the
11389frame specified by @var{number_of_frames}.
11390
f2f3ccb9
SM
11391@item $_as_string(@var{value})
11392@findex $_as_string@r{, convenience function}
11393Return the string representation of @var{value}.
11394
11395This function is useful to obtain the textual label (enumerator) of an
11396enumeration value. For example, assuming the variable @var{node} is of
11397an enumerated type:
11398
11399@smallexample
11400(gdb) printf "Visiting node of type %s\n", $_as_string(node)
11401Visiting node of type NODE_INTEGER
11402@end smallexample
11403
a72c3253
DE
11404@end table
11405
11406@value{GDBN} provides the ability to list and get help on
11407convenience functions.
11408
bc3b79fd
TJB
11409@table @code
11410@item help function
11411@kindex help function
11412@cindex show all convenience functions
11413Print a list of all convenience functions.
11414@end table
11415
6d2ebf8b 11416@node Registers
c906108c
SS
11417@section Registers
11418
11419@cindex registers
11420You can refer to machine register contents, in expressions, as variables
11421with names starting with @samp{$}. The names of registers are different
11422for each machine; use @code{info registers} to see the names used on
11423your machine.
11424
11425@table @code
11426@kindex info registers
11427@item info registers
11428Print the names and values of all registers except floating-point
c85508ee 11429and vector registers (in the selected stack frame).
c906108c
SS
11430
11431@kindex info all-registers
11432@cindex floating point registers
11433@item info all-registers
11434Print the names and values of all registers, including floating-point
c85508ee 11435and vector registers (in the selected stack frame).
c906108c 11436
b67d92b0
SH
11437@item info registers @var{reggroup} @dots{}
11438Print the name and value of the registers in each of the specified
11439@var{reggroup}s. The @var{reggoup} can be any of those returned by
11440@code{maint print reggroups} (@pxref{Maintenance Commands}).
11441
c906108c
SS
11442@item info registers @var{regname} @dots{}
11443Print the @dfn{relativized} value of each specified register @var{regname}.
5d161b24 11444As discussed in detail below, register values are normally relative to
697aa1b7 11445the selected stack frame. The @var{regname} may be any register name valid on
c906108c
SS
11446the machine you are using, with or without the initial @samp{$}.
11447@end table
11448
f5b95c01 11449@anchor{standard registers}
e09f16f9
EZ
11450@cindex stack pointer register
11451@cindex program counter register
11452@cindex process status register
11453@cindex frame pointer register
11454@cindex standard registers
c906108c
SS
11455@value{GDBN} has four ``standard'' register names that are available (in
11456expressions) on most machines---whenever they do not conflict with an
11457architecture's canonical mnemonics for registers. The register names
11458@code{$pc} and @code{$sp} are used for the program counter register and
11459the stack pointer. @code{$fp} is used for a register that contains a
11460pointer to the current stack frame, and @code{$ps} is used for a
11461register that contains the processor status. For example,
11462you could print the program counter in hex with
11463
474c8240 11464@smallexample
c906108c 11465p/x $pc
474c8240 11466@end smallexample
c906108c
SS
11467
11468@noindent
11469or print the instruction to be executed next with
11470
474c8240 11471@smallexample
c906108c 11472x/i $pc
474c8240 11473@end smallexample
c906108c
SS
11474
11475@noindent
11476or add four to the stack pointer@footnote{This is a way of removing
11477one word from the stack, on machines where stacks grow downward in
11478memory (most machines, nowadays). This assumes that the innermost
11479stack frame is selected; setting @code{$sp} is not allowed when other
11480stack frames are selected. To pop entire frames off the stack,
11481regardless of machine architecture, use @code{return};
79a6e687 11482see @ref{Returning, ,Returning from a Function}.} with
c906108c 11483
474c8240 11484@smallexample
c906108c 11485set $sp += 4
474c8240 11486@end smallexample
c906108c
SS
11487
11488Whenever possible, these four standard register names are available on
11489your machine even though the machine has different canonical mnemonics,
11490so long as there is no conflict. The @code{info registers} command
11491shows the canonical names. For example, on the SPARC, @code{info
11492registers} displays the processor status register as @code{$psr} but you
d4f3574e
SS
11493can also refer to it as @code{$ps}; and on x86-based machines @code{$ps}
11494is an alias for the @sc{eflags} register.
c906108c
SS
11495
11496@value{GDBN} always considers the contents of an ordinary register as an
11497integer when the register is examined in this way. Some machines have
11498special registers which can hold nothing but floating point; these
11499registers are considered to have floating point values. There is no way
11500to refer to the contents of an ordinary register as floating point value
11501(although you can @emph{print} it as a floating point value with
11502@samp{print/f $@var{regname}}).
11503
11504Some registers have distinct ``raw'' and ``virtual'' data formats. This
11505means that the data format in which the register contents are saved by
11506the operating system is not the same one that your program normally
11507sees. For example, the registers of the 68881 floating point
11508coprocessor are always saved in ``extended'' (raw) format, but all C
11509programs expect to work with ``double'' (virtual) format. In such
5d161b24 11510cases, @value{GDBN} normally works with the virtual format only (the format
c906108c
SS
11511that makes sense for your program), but the @code{info registers} command
11512prints the data in both formats.
11513
36b80e65
EZ
11514@cindex SSE registers (x86)
11515@cindex MMX registers (x86)
11516Some machines have special registers whose contents can be interpreted
11517in several different ways. For example, modern x86-based machines
11518have SSE and MMX registers that can hold several values packed
11519together in several different formats. @value{GDBN} refers to such
11520registers in @code{struct} notation:
11521
11522@smallexample
11523(@value{GDBP}) print $xmm1
11524$1 = @{
11525 v4_float = @{0, 3.43859137e-038, 1.54142831e-044, 1.821688e-044@},
11526 v2_double = @{9.92129282474342e-303, 2.7585945287983262e-313@},
11527 v16_int8 = "\000\000\000\000\3706;\001\v\000\000\000\r\000\000",
11528 v8_int16 = @{0, 0, 14072, 315, 11, 0, 13, 0@},
11529 v4_int32 = @{0, 20657912, 11, 13@},
11530 v2_int64 = @{88725056443645952, 55834574859@},
11531 uint128 = 0x0000000d0000000b013b36f800000000
11532@}
11533@end smallexample
11534
11535@noindent
11536To set values of such registers, you need to tell @value{GDBN} which
11537view of the register you wish to change, as if you were assigning
11538value to a @code{struct} member:
11539
11540@smallexample
11541 (@value{GDBP}) set $xmm1.uint128 = 0x000000000000000000000000FFFFFFFF
11542@end smallexample
11543
c906108c 11544Normally, register values are relative to the selected stack frame
79a6e687 11545(@pxref{Selection, ,Selecting a Frame}). This means that you get the
c906108c
SS
11546value that the register would contain if all stack frames farther in
11547were exited and their saved registers restored. In order to see the
11548true contents of hardware registers, you must select the innermost
11549frame (with @samp{frame 0}).
11550
901461f8
PA
11551@cindex caller-saved registers
11552@cindex call-clobbered registers
11553@cindex volatile registers
11554@cindex <not saved> values
11555Usually ABIs reserve some registers as not needed to be saved by the
11556callee (a.k.a.: ``caller-saved'', ``call-clobbered'' or ``volatile''
11557registers). It may therefore not be possible for @value{GDBN} to know
11558the value a register had before the call (in other words, in the outer
11559frame), if the register value has since been changed by the callee.
11560@value{GDBN} tries to deduce where the inner frame saved
11561(``callee-saved'') registers, from the debug info, unwind info, or the
11562machine code generated by your compiler. If some register is not
11563saved, and @value{GDBN} knows the register is ``caller-saved'' (via
11564its own knowledge of the ABI, or because the debug/unwind info
11565explicitly says the register's value is undefined), @value{GDBN}
11566displays @w{@samp{<not saved>}} as the register's value. With targets
11567that @value{GDBN} has no knowledge of the register saving convention,
11568if a register was not saved by the callee, then its value and location
11569in the outer frame are assumed to be the same of the inner frame.
11570This is usually harmless, because if the register is call-clobbered,
11571the caller either does not care what is in the register after the
11572call, or has code to restore the value that it does care about. Note,
11573however, that if you change such a register in the outer frame, you
11574may also be affecting the inner frame. Also, the more ``outer'' the
11575frame is you're looking at, the more likely a call-clobbered
11576register's value is to be wrong, in the sense that it doesn't actually
11577represent the value the register had just before the call.
c906108c 11578
6d2ebf8b 11579@node Floating Point Hardware
79a6e687 11580@section Floating Point Hardware
c906108c
SS
11581@cindex floating point
11582
11583Depending on the configuration, @value{GDBN} may be able to give
11584you more information about the status of the floating point hardware.
11585
11586@table @code
11587@kindex info float
11588@item info float
11589Display hardware-dependent information about the floating
11590point unit. The exact contents and layout vary depending on the
11591floating point chip. Currently, @samp{info float} is supported on
11592the ARM and x86 machines.
11593@end table
c906108c 11594
e76f1f2e
AC
11595@node Vector Unit
11596@section Vector Unit
11597@cindex vector unit
11598
11599Depending on the configuration, @value{GDBN} may be able to give you
11600more information about the status of the vector unit.
11601
11602@table @code
11603@kindex info vector
11604@item info vector
11605Display information about the vector unit. The exact contents and
11606layout vary depending on the hardware.
11607@end table
11608
721c2651 11609@node OS Information
79a6e687 11610@section Operating System Auxiliary Information
721c2651
EZ
11611@cindex OS information
11612
11613@value{GDBN} provides interfaces to useful OS facilities that can help
11614you debug your program.
11615
b383017d
RM
11616@cindex auxiliary vector
11617@cindex vector, auxiliary
b383017d
RM
11618Some operating systems supply an @dfn{auxiliary vector} to programs at
11619startup. This is akin to the arguments and environment that you
11620specify for a program, but contains a system-dependent variety of
11621binary values that tell system libraries important details about the
11622hardware, operating system, and process. Each value's purpose is
11623identified by an integer tag; the meanings are well-known but system-specific.
11624Depending on the configuration and operating system facilities,
9c16f35a
EZ
11625@value{GDBN} may be able to show you this information. For remote
11626targets, this functionality may further depend on the remote stub's
427c3a89
DJ
11627support of the @samp{qXfer:auxv:read} packet, see
11628@ref{qXfer auxiliary vector read}.
b383017d
RM
11629
11630@table @code
11631@kindex info auxv
11632@item info auxv
11633Display the auxiliary vector of the inferior, which can be either a
e4937fc1 11634live process or a core dump file. @value{GDBN} prints each tag value
b383017d
RM
11635numerically, and also shows names and text descriptions for recognized
11636tags. Some values in the vector are numbers, some bit masks, and some
e4937fc1 11637pointers to strings or other data. @value{GDBN} displays each value in the
b383017d
RM
11638most appropriate form for a recognized tag, and in hexadecimal for
11639an unrecognized tag.
11640@end table
11641
85d4a676
SS
11642On some targets, @value{GDBN} can access operating system-specific
11643information and show it to you. The types of information available
11644will differ depending on the type of operating system running on the
11645target. The mechanism used to fetch the data is described in
11646@ref{Operating System Information}. For remote targets, this
11647functionality depends on the remote stub's support of the
07e059b5
VP
11648@samp{qXfer:osdata:read} packet, see @ref{qXfer osdata read}.
11649
11650@table @code
a61408f8 11651@kindex info os
85d4a676
SS
11652@item info os @var{infotype}
11653
11654Display OS information of the requested type.
a61408f8 11655
85d4a676
SS
11656On @sc{gnu}/Linux, the following values of @var{infotype} are valid:
11657
11658@anchor{linux info os infotypes}
11659@table @code
d33279b3
AT
11660@kindex info os cpus
11661@item cpus
11662Display the list of all CPUs/cores. For each CPU/core, @value{GDBN} prints
11663the available fields from /proc/cpuinfo. For each supported architecture
11664different fields are available. Two common entries are processor which gives
11665CPU number and bogomips; a system constant that is calculated during
11666kernel initialization.
11667
11668@kindex info os files
11669@item files
11670Display the list of open file descriptors on the target. For each
11671file descriptor, @value{GDBN} prints the identifier of the process
11672owning the descriptor, the command of the owning process, the value
11673of the descriptor, and the target of the descriptor.
11674
11675@kindex info os modules
11676@item modules
11677Display the list of all loaded kernel modules on the target. For each
11678module, @value{GDBN} prints the module name, the size of the module in
11679bytes, the number of times the module is used, the dependencies of the
11680module, the status of the module, and the address of the loaded module
11681in memory.
11682
11683@kindex info os msg
11684@item msg
11685Display the list of all System V message queues on the target. For each
11686message queue, @value{GDBN} prints the message queue key, the message
11687queue identifier, the access permissions, the current number of bytes
11688on the queue, the current number of messages on the queue, the processes
11689that last sent and received a message on the queue, the user and group
11690of the owner and creator of the message queue, the times at which a
11691message was last sent and received on the queue, and the time at which
11692the message queue was last changed.
11693
07e059b5 11694@kindex info os processes
85d4a676 11695@item processes
07e059b5 11696Display the list of processes on the target. For each process,
85d4a676
SS
11697@value{GDBN} prints the process identifier, the name of the user, the
11698command corresponding to the process, and the list of processor cores
11699that the process is currently running on. (To understand what these
11700properties mean, for this and the following info types, please consult
11701the general @sc{gnu}/Linux documentation.)
11702
11703@kindex info os procgroups
11704@item procgroups
11705Display the list of process groups on the target. For each process,
11706@value{GDBN} prints the identifier of the process group that it belongs
11707to, the command corresponding to the process group leader, the process
11708identifier, and the command line of the process. The list is sorted
11709first by the process group identifier, then by the process identifier,
11710so that processes belonging to the same process group are grouped together
11711and the process group leader is listed first.
11712
d33279b3
AT
11713@kindex info os semaphores
11714@item semaphores
11715Display the list of all System V semaphore sets on the target. For each
11716semaphore set, @value{GDBN} prints the semaphore set key, the semaphore
11717set identifier, the access permissions, the number of semaphores in the
11718set, the user and group of the owner and creator of the semaphore set,
11719and the times at which the semaphore set was operated upon and changed.
85d4a676
SS
11720
11721@kindex info os shm
11722@item shm
11723Display the list of all System V shared-memory regions on the target.
11724For each shared-memory region, @value{GDBN} prints the region key,
11725the shared-memory identifier, the access permissions, the size of the
11726region, the process that created the region, the process that last
11727attached to or detached from the region, the current number of live
11728attaches to the region, and the times at which the region was last
11729attached to, detach from, and changed.
11730
d33279b3
AT
11731@kindex info os sockets
11732@item sockets
11733Display the list of Internet-domain sockets on the target. For each
11734socket, @value{GDBN} prints the address and port of the local and
11735remote endpoints, the current state of the connection, the creator of
11736the socket, the IP address family of the socket, and the type of the
11737connection.
85d4a676 11738
d33279b3
AT
11739@kindex info os threads
11740@item threads
11741Display the list of threads running on the target. For each thread,
11742@value{GDBN} prints the identifier of the process that the thread
11743belongs to, the command of the process, the thread identifier, and the
11744processor core that it is currently running on. The main thread of a
11745process is not listed.
85d4a676
SS
11746@end table
11747
11748@item info os
11749If @var{infotype} is omitted, then list the possible values for
11750@var{infotype} and the kind of OS information available for each
11751@var{infotype}. If the target does not return a list of possible
11752types, this command will report an error.
07e059b5 11753@end table
721c2651 11754
29e57380 11755@node Memory Region Attributes
79a6e687 11756@section Memory Region Attributes
29e57380
C
11757@cindex memory region attributes
11758
b383017d 11759@dfn{Memory region attributes} allow you to describe special handling
fd79ecee
DJ
11760required by regions of your target's memory. @value{GDBN} uses
11761attributes to determine whether to allow certain types of memory
11762accesses; whether to use specific width accesses; and whether to cache
11763target memory. By default the description of memory regions is
11764fetched from the target (if the current target supports this), but the
11765user can override the fetched regions.
29e57380
C
11766
11767Defined memory regions can be individually enabled and disabled. When a
11768memory region is disabled, @value{GDBN} uses the default attributes when
11769accessing memory in that region. Similarly, if no memory regions have
11770been defined, @value{GDBN} uses the default attributes when accessing
11771all memory.
11772
b383017d 11773When a memory region is defined, it is given a number to identify it;
29e57380
C
11774to enable, disable, or remove a memory region, you specify that number.
11775
11776@table @code
11777@kindex mem
bfac230e 11778@item mem @var{lower} @var{upper} @var{attributes}@dots{}
09d4efe1
EZ
11779Define a memory region bounded by @var{lower} and @var{upper} with
11780attributes @var{attributes}@dots{}, and add it to the list of regions
11781monitored by @value{GDBN}. Note that @var{upper} == 0 is a special
d3e8051b 11782case: it is treated as the target's maximum memory address.
bfac230e 11783(0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.)
29e57380 11784
fd79ecee
DJ
11785@item mem auto
11786Discard any user changes to the memory regions and use target-supplied
11787regions, if available, or no regions if the target does not support.
11788
29e57380
C
11789@kindex delete mem
11790@item delete mem @var{nums}@dots{}
09d4efe1
EZ
11791Remove memory regions @var{nums}@dots{} from the list of regions
11792monitored by @value{GDBN}.
29e57380
C
11793
11794@kindex disable mem
11795@item disable mem @var{nums}@dots{}
09d4efe1 11796Disable monitoring of memory regions @var{nums}@dots{}.
b383017d 11797A disabled memory region is not forgotten.
29e57380
C
11798It may be enabled again later.
11799
11800@kindex enable mem
11801@item enable mem @var{nums}@dots{}
09d4efe1 11802Enable monitoring of memory regions @var{nums}@dots{}.
29e57380
C
11803
11804@kindex info mem
11805@item info mem
11806Print a table of all defined memory regions, with the following columns
09d4efe1 11807for each region:
29e57380
C
11808
11809@table @emph
11810@item Memory Region Number
11811@item Enabled or Disabled.
b383017d 11812Enabled memory regions are marked with @samp{y}.
29e57380
C
11813Disabled memory regions are marked with @samp{n}.
11814
11815@item Lo Address
11816The address defining the inclusive lower bound of the memory region.
11817
11818@item Hi Address
11819The address defining the exclusive upper bound of the memory region.
11820
11821@item Attributes
11822The list of attributes set for this memory region.
11823@end table
11824@end table
11825
11826
11827@subsection Attributes
11828
b383017d 11829@subsubsection Memory Access Mode
29e57380
C
11830The access mode attributes set whether @value{GDBN} may make read or
11831write accesses to a memory region.
11832
11833While these attributes prevent @value{GDBN} from performing invalid
11834memory accesses, they do nothing to prevent the target system, I/O DMA,
359df76b 11835etc.@: from accessing memory.
29e57380
C
11836
11837@table @code
11838@item ro
11839Memory is read only.
11840@item wo
11841Memory is write only.
11842@item rw
6ca652b0 11843Memory is read/write. This is the default.
29e57380
C
11844@end table
11845
11846@subsubsection Memory Access Size
d3e8051b 11847The access size attribute tells @value{GDBN} to use specific sized
29e57380
C
11848accesses in the memory region. Often memory mapped device registers
11849require specific sized accesses. If no access size attribute is
11850specified, @value{GDBN} may use accesses of any size.
11851
11852@table @code
11853@item 8
11854Use 8 bit memory accesses.
11855@item 16
11856Use 16 bit memory accesses.
11857@item 32
11858Use 32 bit memory accesses.
11859@item 64
11860Use 64 bit memory accesses.
11861@end table
11862
11863@c @subsubsection Hardware/Software Breakpoints
11864@c The hardware/software breakpoint attributes set whether @value{GDBN}
11865@c will use hardware or software breakpoints for the internal breakpoints
11866@c used by the step, next, finish, until, etc. commands.
11867@c
11868@c @table @code
11869@c @item hwbreak
b383017d 11870@c Always use hardware breakpoints
29e57380
C
11871@c @item swbreak (default)
11872@c @end table
11873
11874@subsubsection Data Cache
11875The data cache attributes set whether @value{GDBN} will cache target
11876memory. While this generally improves performance by reducing debug
11877protocol overhead, it can lead to incorrect results because @value{GDBN}
11878does not know about volatile variables or memory mapped device
11879registers.
11880
11881@table @code
11882@item cache
b383017d 11883Enable @value{GDBN} to cache target memory.
6ca652b0
EZ
11884@item nocache
11885Disable @value{GDBN} from caching target memory. This is the default.
29e57380
C
11886@end table
11887
4b5752d0
VP
11888@subsection Memory Access Checking
11889@value{GDBN} can be instructed to refuse accesses to memory that is
11890not explicitly described. This can be useful if accessing such
11891regions has undesired effects for a specific target, or to provide
11892better error checking. The following commands control this behaviour.
11893
11894@table @code
11895@kindex set mem inaccessible-by-default
11896@item set mem inaccessible-by-default [on|off]
11897If @code{on} is specified, make @value{GDBN} treat memory not
11898explicitly described by the memory ranges as non-existent and refuse accesses
11899to such memory. The checks are only performed if there's at least one
11900memory range defined. If @code{off} is specified, make @value{GDBN}
11901treat the memory not explicitly described by the memory ranges as RAM.
56cf5405 11902The default value is @code{on}.
4b5752d0
VP
11903@kindex show mem inaccessible-by-default
11904@item show mem inaccessible-by-default
11905Show the current handling of accesses to unknown memory.
11906@end table
11907
11908
29e57380 11909@c @subsubsection Memory Write Verification
b383017d 11910@c The memory write verification attributes set whether @value{GDBN}
29e57380
C
11911@c will re-reads data after each write to verify the write was successful.
11912@c
11913@c @table @code
11914@c @item verify
11915@c @item noverify (default)
11916@c @end table
11917
16d9dec6 11918@node Dump/Restore Files
79a6e687 11919@section Copy Between Memory and a File
16d9dec6
MS
11920@cindex dump/restore files
11921@cindex append data to a file
11922@cindex dump data to a file
11923@cindex restore data from a file
16d9dec6 11924
df5215a6
JB
11925You can use the commands @code{dump}, @code{append}, and
11926@code{restore} to copy data between target memory and a file. The
11927@code{dump} and @code{append} commands write data to a file, and the
11928@code{restore} command reads data from a file back into the inferior's
cf75d6c3
AB
11929memory. Files may be in binary, Motorola S-record, Intel hex,
11930Tektronix Hex, or Verilog Hex format; however, @value{GDBN} can only
11931append to binary files, and cannot read from Verilog Hex files.
df5215a6
JB
11932
11933@table @code
11934
11935@kindex dump
11936@item dump @r{[}@var{format}@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
11937@itemx dump @r{[}@var{format}@r{]} value @var{filename} @var{expr}
11938Dump the contents of memory from @var{start_addr} to @var{end_addr},
11939or the value of @var{expr}, to @var{filename} in the given format.
16d9dec6 11940
df5215a6 11941The @var{format} parameter may be any one of:
16d9dec6 11942@table @code
df5215a6
JB
11943@item binary
11944Raw binary form.
11945@item ihex
11946Intel hex format.
11947@item srec
11948Motorola S-record format.
11949@item tekhex
11950Tektronix Hex format.
cf75d6c3
AB
11951@item verilog
11952Verilog Hex format.
df5215a6
JB
11953@end table
11954
11955@value{GDBN} uses the same definitions of these formats as the
11956@sc{gnu} binary utilities, like @samp{objdump} and @samp{objcopy}. If
11957@var{format} is omitted, @value{GDBN} dumps the data in raw binary
11958form.
11959
11960@kindex append
11961@item append @r{[}binary@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
11962@itemx append @r{[}binary@r{]} value @var{filename} @var{expr}
11963Append the contents of memory from @var{start_addr} to @var{end_addr},
09d4efe1 11964or the value of @var{expr}, to the file @var{filename}, in raw binary form.
df5215a6
JB
11965(@value{GDBN} can only append data to files in raw binary form.)
11966
11967@kindex restore
11968@item restore @var{filename} @r{[}binary@r{]} @var{bias} @var{start} @var{end}
11969Restore the contents of file @var{filename} into memory. The
11970@code{restore} command can automatically recognize any known @sc{bfd}
11971file format, except for raw binary. To restore a raw binary file you
11972must specify the optional keyword @code{binary} after the filename.
16d9dec6 11973
b383017d 11974If @var{bias} is non-zero, its value will be added to the addresses
16d9dec6
MS
11975contained in the file. Binary files always start at address zero, so
11976they will be restored at address @var{bias}. Other bfd files have
11977a built-in location; they will be restored at offset @var{bias}
11978from that location.
11979
11980If @var{start} and/or @var{end} are non-zero, then only data between
11981file offset @var{start} and file offset @var{end} will be restored.
b383017d 11982These offsets are relative to the addresses in the file, before
16d9dec6
MS
11983the @var{bias} argument is applied.
11984
11985@end table
11986
384ee23f
EZ
11987@node Core File Generation
11988@section How to Produce a Core File from Your Program
11989@cindex dump core from inferior
11990
11991A @dfn{core file} or @dfn{core dump} is a file that records the memory
11992image of a running process and its process status (register values
11993etc.). Its primary use is post-mortem debugging of a program that
11994crashed while it ran outside a debugger. A program that crashes
11995automatically produces a core file, unless this feature is disabled by
11996the user. @xref{Files}, for information on invoking @value{GDBN} in
11997the post-mortem debugging mode.
11998
11999Occasionally, you may wish to produce a core file of the program you
12000are debugging in order to preserve a snapshot of its state.
12001@value{GDBN} has a special command for that.
12002
12003@table @code
12004@kindex gcore
12005@kindex generate-core-file
12006@item generate-core-file [@var{file}]
12007@itemx gcore [@var{file}]
12008Produce a core dump of the inferior process. The optional argument
12009@var{file} specifies the file name where to put the core dump. If not
12010specified, the file name defaults to @file{core.@var{pid}}, where
12011@var{pid} is the inferior process ID.
12012
12013Note that this command is implemented only for some systems (as of
05b4bd79 12014this writing, @sc{gnu}/Linux, FreeBSD, Solaris, and S390).
df8411da
SDJ
12015
12016On @sc{gnu}/Linux, this command can take into account the value of the
12017file @file{/proc/@var{pid}/coredump_filter} when generating the core
1e52e849
SL
12018dump (@pxref{set use-coredump-filter}), and by default honors the
12019@code{VM_DONTDUMP} flag for mappings where it is present in the file
12020@file{/proc/@var{pid}/smaps} (@pxref{set dump-excluded-mappings}).
df8411da
SDJ
12021
12022@kindex set use-coredump-filter
12023@anchor{set use-coredump-filter}
12024@item set use-coredump-filter on
12025@itemx set use-coredump-filter off
12026Enable or disable the use of the file
12027@file{/proc/@var{pid}/coredump_filter} when generating core dump
12028files. This file is used by the Linux kernel to decide what types of
12029memory mappings will be dumped or ignored when generating a core dump
12030file. @var{pid} is the process ID of a currently running process.
12031
12032To make use of this feature, you have to write in the
12033@file{/proc/@var{pid}/coredump_filter} file a value, in hexadecimal,
12034which is a bit mask representing the memory mapping types. If a bit
12035is set in the bit mask, then the memory mappings of the corresponding
12036types will be dumped; otherwise, they will be ignored. This
12037configuration is inherited by child processes. For more information
12038about the bits that can be set in the
12039@file{/proc/@var{pid}/coredump_filter} file, please refer to the
12040manpage of @code{core(5)}.
12041
12042By default, this option is @code{on}. If this option is turned
12043@code{off}, @value{GDBN} does not read the @file{coredump_filter} file
12044and instead uses the same default value as the Linux kernel in order
12045to decide which pages will be dumped in the core dump file. This
12046value is currently @code{0x33}, which means that bits @code{0}
12047(anonymous private mappings), @code{1} (anonymous shared mappings),
12048@code{4} (ELF headers) and @code{5} (private huge pages) are active.
12049This will cause these memory mappings to be dumped automatically.
1e52e849
SL
12050
12051@kindex set dump-excluded-mappings
12052@anchor{set dump-excluded-mappings}
12053@item set dump-excluded-mappings on
12054@itemx set dump-excluded-mappings off
12055If @code{on} is specified, @value{GDBN} will dump memory mappings
12056marked with the @code{VM_DONTDUMP} flag. This flag is represented in
12057the file @file{/proc/@var{pid}/smaps} with the acronym @code{dd}.
12058
12059The default value is @code{off}.
384ee23f
EZ
12060@end table
12061
a0eb71c5
KB
12062@node Character Sets
12063@section Character Sets
12064@cindex character sets
12065@cindex charset
12066@cindex translating between character sets
12067@cindex host character set
12068@cindex target character set
12069
12070If the program you are debugging uses a different character set to
12071represent characters and strings than the one @value{GDBN} uses itself,
12072@value{GDBN} can automatically translate between the character sets for
12073you. The character set @value{GDBN} uses we call the @dfn{host
12074character set}; the one the inferior program uses we call the
12075@dfn{target character set}.
12076
12077For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which
12078uses the ISO Latin 1 character set, but you are using @value{GDBN}'s
ea35711c 12079remote protocol (@pxref{Remote Debugging}) to debug a program
a0eb71c5
KB
12080running on an IBM mainframe, which uses the @sc{ebcdic} character set,
12081then the host character set is Latin-1, and the target character set is
12082@sc{ebcdic}. If you give @value{GDBN} the command @code{set
e33d66ec 12083target-charset EBCDIC-US}, then @value{GDBN} translates between
a0eb71c5
KB
12084@sc{ebcdic} and Latin 1 as you print character or string values, or use
12085character and string literals in expressions.
12086
12087@value{GDBN} has no way to automatically recognize which character set
12088the inferior program uses; you must tell it, using the @code{set
12089target-charset} command, described below.
12090
12091Here are the commands for controlling @value{GDBN}'s character set
12092support:
12093
12094@table @code
12095@item set target-charset @var{charset}
12096@kindex set target-charset
10af6951
EZ
12097Set the current target character set to @var{charset}. To display the
12098list of supported target character sets, type
12099@kbd{@w{set target-charset @key{TAB}@key{TAB}}}.
a0eb71c5 12100
a0eb71c5
KB
12101@item set host-charset @var{charset}
12102@kindex set host-charset
12103Set the current host character set to @var{charset}.
12104
12105By default, @value{GDBN} uses a host character set appropriate to the
12106system it is running on; you can override that default using the
732f6a93
TT
12107@code{set host-charset} command. On some systems, @value{GDBN} cannot
12108automatically determine the appropriate host character set. In this
12109case, @value{GDBN} uses @samp{UTF-8}.
a0eb71c5
KB
12110
12111@value{GDBN} can only use certain character sets as its host character
c1b6b909 12112set. If you type @kbd{@w{set host-charset @key{TAB}@key{TAB}}},
10af6951 12113@value{GDBN} will list the host character sets it supports.
a0eb71c5
KB
12114
12115@item set charset @var{charset}
12116@kindex set charset
e33d66ec 12117Set the current host and target character sets to @var{charset}. As
10af6951
EZ
12118above, if you type @kbd{@w{set charset @key{TAB}@key{TAB}}},
12119@value{GDBN} will list the names of the character sets that can be used
e33d66ec
EZ
12120for both host and target.
12121
a0eb71c5 12122@item show charset
a0eb71c5 12123@kindex show charset
10af6951 12124Show the names of the current host and target character sets.
e33d66ec 12125
10af6951 12126@item show host-charset
a0eb71c5 12127@kindex show host-charset
10af6951 12128Show the name of the current host character set.
e33d66ec 12129
10af6951 12130@item show target-charset
a0eb71c5 12131@kindex show target-charset
10af6951 12132Show the name of the current target character set.
a0eb71c5 12133
10af6951
EZ
12134@item set target-wide-charset @var{charset}
12135@kindex set target-wide-charset
12136Set the current target's wide character set to @var{charset}. This is
12137the character set used by the target's @code{wchar_t} type. To
12138display the list of supported wide character sets, type
12139@kbd{@w{set target-wide-charset @key{TAB}@key{TAB}}}.
12140
12141@item show target-wide-charset
12142@kindex show target-wide-charset
12143Show the name of the current target's wide character set.
a0eb71c5
KB
12144@end table
12145
a0eb71c5
KB
12146Here is an example of @value{GDBN}'s character set support in action.
12147Assume that the following source code has been placed in the file
12148@file{charset-test.c}:
12149
12150@smallexample
12151#include <stdio.h>
12152
12153char ascii_hello[]
12154 = @{72, 101, 108, 108, 111, 44, 32, 119,
12155 111, 114, 108, 100, 33, 10, 0@};
12156char ibm1047_hello[]
12157 = @{200, 133, 147, 147, 150, 107, 64, 166,
12158 150, 153, 147, 132, 90, 37, 0@};
12159
12160main ()
12161@{
12162 printf ("Hello, world!\n");
12163@}
10998722 12164@end smallexample
a0eb71c5
KB
12165
12166In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays
12167containing the string @samp{Hello, world!} followed by a newline,
12168encoded in the @sc{ascii} and @sc{ibm1047} character sets.
12169
12170We compile the program, and invoke the debugger on it:
12171
12172@smallexample
12173$ gcc -g charset-test.c -o charset-test
12174$ gdb -nw charset-test
12175GNU gdb 2001-12-19-cvs
12176Copyright 2001 Free Software Foundation, Inc.
12177@dots{}
f7dc1244 12178(@value{GDBP})
10998722 12179@end smallexample
a0eb71c5
KB
12180
12181We can use the @code{show charset} command to see what character sets
12182@value{GDBN} is currently using to interpret and display characters and
12183strings:
12184
12185@smallexample
f7dc1244 12186(@value{GDBP}) show charset
e33d66ec 12187The current host and target character set is `ISO-8859-1'.
f7dc1244 12188(@value{GDBP})
10998722 12189@end smallexample
a0eb71c5
KB
12190
12191For the sake of printing this manual, let's use @sc{ascii} as our
12192initial character set:
12193@smallexample
f7dc1244
EZ
12194(@value{GDBP}) set charset ASCII
12195(@value{GDBP}) show charset
e33d66ec 12196The current host and target character set is `ASCII'.
f7dc1244 12197(@value{GDBP})
10998722 12198@end smallexample
a0eb71c5
KB
12199
12200Let's assume that @sc{ascii} is indeed the correct character set for our
12201host system --- in other words, let's assume that if @value{GDBN} prints
12202characters using the @sc{ascii} character set, our terminal will display
12203them properly. Since our current target character set is also
12204@sc{ascii}, the contents of @code{ascii_hello} print legibly:
12205
12206@smallexample
f7dc1244 12207(@value{GDBP}) print ascii_hello
a0eb71c5 12208$1 = 0x401698 "Hello, world!\n"
f7dc1244 12209(@value{GDBP}) print ascii_hello[0]
a0eb71c5 12210$2 = 72 'H'
f7dc1244 12211(@value{GDBP})
10998722 12212@end smallexample
a0eb71c5
KB
12213
12214@value{GDBN} uses the target character set for character and string
12215literals you use in expressions:
12216
12217@smallexample
f7dc1244 12218(@value{GDBP}) print '+'
a0eb71c5 12219$3 = 43 '+'
f7dc1244 12220(@value{GDBP})
10998722 12221@end smallexample
a0eb71c5
KB
12222
12223The @sc{ascii} character set uses the number 43 to encode the @samp{+}
12224character.
12225
12226@value{GDBN} relies on the user to tell it which character set the
12227target program uses. If we print @code{ibm1047_hello} while our target
12228character set is still @sc{ascii}, we get jibberish:
12229
12230@smallexample
f7dc1244 12231(@value{GDBP}) print ibm1047_hello
a0eb71c5 12232$4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%"
f7dc1244 12233(@value{GDBP}) print ibm1047_hello[0]
a0eb71c5 12234$5 = 200 '\310'
f7dc1244 12235(@value{GDBP})
10998722 12236@end smallexample
a0eb71c5 12237
e33d66ec 12238If we invoke the @code{set target-charset} followed by @key{TAB}@key{TAB},
a0eb71c5
KB
12239@value{GDBN} tells us the character sets it supports:
12240
12241@smallexample
f7dc1244 12242(@value{GDBP}) set target-charset
b383017d 12243ASCII EBCDIC-US IBM1047 ISO-8859-1
f7dc1244 12244(@value{GDBP}) set target-charset
10998722 12245@end smallexample
a0eb71c5
KB
12246
12247We can select @sc{ibm1047} as our target character set, and examine the
12248program's strings again. Now the @sc{ascii} string is wrong, but
12249@value{GDBN} translates the contents of @code{ibm1047_hello} from the
12250target character set, @sc{ibm1047}, to the host character set,
12251@sc{ascii}, and they display correctly:
12252
12253@smallexample
f7dc1244
EZ
12254(@value{GDBP}) set target-charset IBM1047
12255(@value{GDBP}) show charset
e33d66ec
EZ
12256The current host character set is `ASCII'.
12257The current target character set is `IBM1047'.
f7dc1244 12258(@value{GDBP}) print ascii_hello
a0eb71c5 12259$6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012"
f7dc1244 12260(@value{GDBP}) print ascii_hello[0]
a0eb71c5 12261$7 = 72 '\110'
f7dc1244 12262(@value{GDBP}) print ibm1047_hello
a0eb71c5 12263$8 = 0x4016a8 "Hello, world!\n"
f7dc1244 12264(@value{GDBP}) print ibm1047_hello[0]
a0eb71c5 12265$9 = 200 'H'
f7dc1244 12266(@value{GDBP})
10998722 12267@end smallexample
a0eb71c5
KB
12268
12269As above, @value{GDBN} uses the target character set for character and
12270string literals you use in expressions:
12271
12272@smallexample
f7dc1244 12273(@value{GDBP}) print '+'
a0eb71c5 12274$10 = 78 '+'
f7dc1244 12275(@value{GDBP})
10998722 12276@end smallexample
a0eb71c5 12277
e33d66ec 12278The @sc{ibm1047} character set uses the number 78 to encode the @samp{+}
a0eb71c5
KB
12279character.
12280
b12039c6
YQ
12281@node Caching Target Data
12282@section Caching Data of Targets
12283@cindex caching data of targets
12284
12285@value{GDBN} caches data exchanged between the debugger and a target.
b26dfc9a
YQ
12286Each cache is associated with the address space of the inferior.
12287@xref{Inferiors and Programs}, about inferior and address space.
b12039c6
YQ
12288Such caching generally improves performance in remote debugging
12289(@pxref{Remote Debugging}), because it reduces the overhead of the
12290remote protocol by bundling memory reads and writes into large chunks.
12291Unfortunately, simply caching everything would lead to incorrect results,
12292since @value{GDBN} does not necessarily know anything about volatile
12293values, memory-mapped I/O addresses, etc. Furthermore, in non-stop mode
12294(@pxref{Non-Stop Mode}) memory can be changed @emph{while} a gdb command
12295is executing.
29b090c0
DE
12296Therefore, by default, @value{GDBN} only caches data
12297known to be on the stack@footnote{In non-stop mode, it is moderately
12298rare for a running thread to modify the stack of a stopped thread
12299in a way that would interfere with a backtrace, and caching of
29453a14
YQ
12300stack reads provides a significant speed up of remote backtraces.} or
12301in the code segment.
29b090c0 12302Other regions of memory can be explicitly marked as
27b81af3 12303cacheable; @pxref{Memory Region Attributes}.
09d4efe1
EZ
12304
12305@table @code
12306@kindex set remotecache
12307@item set remotecache on
12308@itemx set remotecache off
4e5d721f
DE
12309This option no longer does anything; it exists for compatibility
12310with old scripts.
09d4efe1
EZ
12311
12312@kindex show remotecache
12313@item show remotecache
4e5d721f
DE
12314Show the current state of the obsolete remotecache flag.
12315
12316@kindex set stack-cache
12317@item set stack-cache on
12318@itemx set stack-cache off
6dd315ba
YQ
12319Enable or disable caching of stack accesses. When @code{on}, use
12320caching. By default, this option is @code{on}.
4e5d721f
DE
12321
12322@kindex show stack-cache
12323@item show stack-cache
12324Show the current state of data caching for memory accesses.
09d4efe1 12325
29453a14
YQ
12326@kindex set code-cache
12327@item set code-cache on
12328@itemx set code-cache off
12329Enable or disable caching of code segment accesses. When @code{on},
12330use caching. By default, this option is @code{on}. This improves
12331performance of disassembly in remote debugging.
12332
12333@kindex show code-cache
12334@item show code-cache
12335Show the current state of target memory cache for code segment
12336accesses.
12337
09d4efe1 12338@kindex info dcache
4e5d721f 12339@item info dcache @r{[}line@r{]}
b26dfc9a
YQ
12340Print the information about the performance of data cache of the
12341current inferior's address space. The information displayed
12342includes the dcache width and depth, and for each cache line, its
12343number, address, and how many times it was referenced. This
12344command is useful for debugging the data cache operation.
4e5d721f
DE
12345
12346If a line number is specified, the contents of that line will be
12347printed in hex.
1a532630
PP
12348
12349@item set dcache size @var{size}
12350@cindex dcache size
12351@kindex set dcache size
12352Set maximum number of entries in dcache (dcache depth above).
12353
12354@item set dcache line-size @var{line-size}
12355@cindex dcache line-size
12356@kindex set dcache line-size
12357Set number of bytes each dcache entry caches (dcache width above).
12358Must be a power of 2.
12359
12360@item show dcache size
12361@kindex show dcache size
b12039c6 12362Show maximum number of dcache entries. @xref{Caching Target Data, info dcache}.
1a532630
PP
12363
12364@item show dcache line-size
12365@kindex show dcache line-size
b12039c6 12366Show default size of dcache lines.
1a532630 12367
09d4efe1
EZ
12368@end table
12369
08388c79
DE
12370@node Searching Memory
12371@section Search Memory
12372@cindex searching memory
12373
12374Memory can be searched for a particular sequence of bytes with the
12375@code{find} command.
12376
12377@table @code
12378@kindex find
12379@item find @r{[}/@var{sn}@r{]} @var{start_addr}, +@var{len}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
12380@itemx find @r{[}/@var{sn}@r{]} @var{start_addr}, @var{end_addr}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
12381Search memory for the sequence of bytes specified by @var{val1}, @var{val2},
12382etc. The search begins at address @var{start_addr} and continues for either
12383@var{len} bytes or through to @var{end_addr} inclusive.
12384@end table
12385
12386@var{s} and @var{n} are optional parameters.
12387They may be specified in either order, apart or together.
12388
12389@table @r
12390@item @var{s}, search query size
12391The size of each search query value.
12392
12393@table @code
12394@item b
12395bytes
12396@item h
12397halfwords (two bytes)
12398@item w
12399words (four bytes)
12400@item g
12401giant words (eight bytes)
12402@end table
12403
12404All values are interpreted in the current language.
12405This means, for example, that if the current source language is C/C@t{++}
12406then searching for the string ``hello'' includes the trailing '\0'.
ee9a09e9
DC
12407The null terminator can be removed from searching by using casts,
12408e.g.: @samp{@{char[5]@}"hello"}.
08388c79
DE
12409
12410If the value size is not specified, it is taken from the
12411value's type in the current language.
12412This is useful when one wants to specify the search
12413pattern as a mixture of types.
12414Note that this means, for example, that in the case of C-like languages
12415a search for an untyped 0x42 will search for @samp{(int) 0x42}
12416which is typically four bytes.
12417
12418@item @var{n}, maximum number of finds
12419The maximum number of matches to print. The default is to print all finds.
12420@end table
12421
12422You can use strings as search values. Quote them with double-quotes
12423 (@code{"}).
12424The string value is copied into the search pattern byte by byte,
12425regardless of the endianness of the target and the size specification.
12426
12427The address of each match found is printed as well as a count of the
12428number of matches found.
12429
12430The address of the last value found is stored in convenience variable
12431@samp{$_}.
12432A count of the number of matches is stored in @samp{$numfound}.
12433
12434For example, if stopped at the @code{printf} in this function:
12435
12436@smallexample
12437void
12438hello ()
12439@{
12440 static char hello[] = "hello-hello";
12441 static struct @{ char c; short s; int i; @}
12442 __attribute__ ((packed)) mixed
12443 = @{ 'c', 0x1234, 0x87654321 @};
12444 printf ("%s\n", hello);
12445@}
12446@end smallexample
12447
12448@noindent
12449you get during debugging:
12450
12451@smallexample
12452(gdb) find &hello[0], +sizeof(hello), "hello"
124530x804956d <hello.1620+6>
124541 pattern found
12455(gdb) find &hello[0], +sizeof(hello), 'h', 'e', 'l', 'l', 'o'
124560x8049567 <hello.1620>
124570x804956d <hello.1620+6>
ee9a09e9
DC
124582 patterns found.
12459(gdb) find &hello[0], +sizeof(hello), @{char[5]@}"hello"
124600x8049567 <hello.1620>
124610x804956d <hello.1620+6>
124622 patterns found.
08388c79
DE
12463(gdb) find /b1 &hello[0], +sizeof(hello), 'h', 0x65, 'l'
124640x8049567 <hello.1620>
124651 pattern found
12466(gdb) find &mixed, +sizeof(mixed), (char) 'c', (short) 0x1234, (int) 0x87654321
124670x8049560 <mixed.1625>
124681 pattern found
12469(gdb) print $numfound
12470$1 = 1
12471(gdb) print $_
12472$2 = (void *) 0x8049560
12473@end smallexample
a0eb71c5 12474
5fdf6324
AB
12475@node Value Sizes
12476@section Value Sizes
12477
12478Whenever @value{GDBN} prints a value memory will be allocated within
12479@value{GDBN} to hold the contents of the value. It is possible in
12480some languages with dynamic typing systems, that an invalid program
12481may indicate a value that is incorrectly large, this in turn may cause
12482@value{GDBN} to try and allocate an overly large ammount of memory.
12483
12484@table @code
12485@kindex set max-value-size
713cdcbf 12486@item set max-value-size @var{bytes}
5fdf6324
AB
12487@itemx set max-value-size unlimited
12488Set the maximum size of memory that @value{GDBN} will allocate for the
12489contents of a value to @var{bytes}, trying to display a value that
12490requires more memory than that will result in an error.
12491
12492Setting this variable does not effect values that have already been
12493allocated within @value{GDBN}, only future allocations.
12494
12495There's a minimum size that @code{max-value-size} can be set to in
12496order that @value{GDBN} can still operate correctly, this minimum is
12497currently 16 bytes.
12498
12499The limit applies to the results of some subexpressions as well as to
12500complete expressions. For example, an expression denoting a simple
12501integer component, such as @code{x.y.z}, may fail if the size of
12502@var{x.y} is dynamic and exceeds @var{bytes}. On the other hand,
12503@value{GDBN} is sometimes clever; the expression @code{A[i]}, where
12504@var{A} is an array variable with non-constant size, will generally
12505succeed regardless of the bounds on @var{A}, as long as the component
12506size is less than @var{bytes}.
12507
12508The default value of @code{max-value-size} is currently 64k.
12509
12510@kindex show max-value-size
12511@item show max-value-size
12512Show the maximum size of memory, in bytes, that @value{GDBN} will
12513allocate for the contents of a value.
12514@end table
12515
edb3359d
DJ
12516@node Optimized Code
12517@chapter Debugging Optimized Code
12518@cindex optimized code, debugging
12519@cindex debugging optimized code
12520
12521Almost all compilers support optimization. With optimization
12522disabled, the compiler generates assembly code that corresponds
12523directly to your source code, in a simplistic way. As the compiler
12524applies more powerful optimizations, the generated assembly code
12525diverges from your original source code. With help from debugging
12526information generated by the compiler, @value{GDBN} can map from
12527the running program back to constructs from your original source.
12528
12529@value{GDBN} is more accurate with optimization disabled. If you
12530can recompile without optimization, it is easier to follow the
12531progress of your program during debugging. But, there are many cases
12532where you may need to debug an optimized version.
12533
12534When you debug a program compiled with @samp{-g -O}, remember that the
12535optimizer has rearranged your code; the debugger shows you what is
12536really there. Do not be too surprised when the execution path does not
12537exactly match your source file! An extreme example: if you define a
12538variable, but never use it, @value{GDBN} never sees that
12539variable---because the compiler optimizes it out of existence.
12540
12541Some things do not work as well with @samp{-g -O} as with just
12542@samp{-g}, particularly on machines with instruction scheduling. If in
12543doubt, recompile with @samp{-g} alone, and if this fixes the problem,
12544please report it to us as a bug (including a test case!).
12545@xref{Variables}, for more information about debugging optimized code.
12546
12547@menu
12548* Inline Functions:: How @value{GDBN} presents inlining
111c6489 12549* Tail Call Frames:: @value{GDBN} analysis of jumps to functions
edb3359d
DJ
12550@end menu
12551
12552@node Inline Functions
12553@section Inline Functions
12554@cindex inline functions, debugging
12555
12556@dfn{Inlining} is an optimization that inserts a copy of the function
12557body directly at each call site, instead of jumping to a shared
12558routine. @value{GDBN} displays inlined functions just like
12559non-inlined functions. They appear in backtraces. You can view their
12560arguments and local variables, step into them with @code{step}, skip
12561them with @code{next}, and escape from them with @code{finish}.
12562You can check whether a function was inlined by using the
12563@code{info frame} command.
12564
12565For @value{GDBN} to support inlined functions, the compiler must
12566record information about inlining in the debug information ---
12567@value{NGCC} using the @sc{dwarf 2} format does this, and several
12568other compilers do also. @value{GDBN} only supports inlined functions
12569when using @sc{dwarf 2}. Versions of @value{NGCC} before 4.1
12570do not emit two required attributes (@samp{DW_AT_call_file} and
12571@samp{DW_AT_call_line}); @value{GDBN} does not display inlined
12572function calls with earlier versions of @value{NGCC}. It instead
12573displays the arguments and local variables of inlined functions as
12574local variables in the caller.
12575
12576The body of an inlined function is directly included at its call site;
12577unlike a non-inlined function, there are no instructions devoted to
12578the call. @value{GDBN} still pretends that the call site and the
12579start of the inlined function are different instructions. Stepping to
12580the call site shows the call site, and then stepping again shows
12581the first line of the inlined function, even though no additional
12582instructions are executed.
12583
12584This makes source-level debugging much clearer; you can see both the
12585context of the call and then the effect of the call. Only stepping by
12586a single instruction using @code{stepi} or @code{nexti} does not do
12587this; single instruction steps always show the inlined body.
12588
12589There are some ways that @value{GDBN} does not pretend that inlined
12590function calls are the same as normal calls:
12591
12592@itemize @bullet
edb3359d
DJ
12593@item
12594Setting breakpoints at the call site of an inlined function may not
12595work, because the call site does not contain any code. @value{GDBN}
12596may incorrectly move the breakpoint to the next line of the enclosing
12597function, after the call. This limitation will be removed in a future
12598version of @value{GDBN}; until then, set a breakpoint on an earlier line
12599or inside the inlined function instead.
12600
12601@item
12602@value{GDBN} cannot locate the return value of inlined calls after
12603using the @code{finish} command. This is a limitation of compiler-generated
12604debugging information; after @code{finish}, you can step to the next line
12605and print a variable where your program stored the return value.
12606
12607@end itemize
12608
111c6489
JK
12609@node Tail Call Frames
12610@section Tail Call Frames
12611@cindex tail call frames, debugging
12612
12613Function @code{B} can call function @code{C} in its very last statement. In
12614unoptimized compilation the call of @code{C} is immediately followed by return
12615instruction at the end of @code{B} code. Optimizing compiler may replace the
12616call and return in function @code{B} into one jump to function @code{C}
12617instead. Such use of a jump instruction is called @dfn{tail call}.
12618
12619During execution of function @code{C}, there will be no indication in the
12620function call stack frames that it was tail-called from @code{B}. If function
12621@code{A} regularly calls function @code{B} which tail-calls function @code{C},
12622then @value{GDBN} will see @code{A} as the caller of @code{C}. However, in
12623some cases @value{GDBN} can determine that @code{C} was tail-called from
12624@code{B}, and it will then create fictitious call frame for that, with the
12625return address set up as if @code{B} called @code{C} normally.
12626
12627This functionality is currently supported only by DWARF 2 debugging format and
216f72a1 12628the compiler has to produce @samp{DW_TAG_call_site} tags. With
111c6489
JK
12629@value{NGCC}, you need to specify @option{-O -g} during compilation, to get
12630this information.
12631
12632@kbd{info frame} command (@pxref{Frame Info}) will indicate the tail call frame
12633kind by text @code{tail call frame} such as in this sample @value{GDBN} output:
12634
12635@smallexample
12636(gdb) x/i $pc - 2
12637 0x40066b <b(int, double)+11>: jmp 0x400640 <c(int, double)>
12638(gdb) info frame
12639Stack level 1, frame at 0x7fffffffda30:
12640 rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
12641 tail call frame, caller of frame at 0x7fffffffda30
12642 source language c++.
12643 Arglist at unknown address.
12644 Locals at unknown address, Previous frame's sp is 0x7fffffffda30
12645@end smallexample
12646
12647The detection of all the possible code path executions can find them ambiguous.
12648There is no execution history stored (possible @ref{Reverse Execution} is never
12649used for this purpose) and the last known caller could have reached the known
12650callee by multiple different jump sequences. In such case @value{GDBN} still
12651tries to show at least all the unambiguous top tail callers and all the
12652unambiguous bottom tail calees, if any.
12653
12654@table @code
e18b2753 12655@anchor{set debug entry-values}
111c6489
JK
12656@item set debug entry-values
12657@kindex set debug entry-values
12658When set to on, enables printing of analysis messages for both frame argument
12659values at function entry and tail calls. It will show all the possible valid
12660tail calls code paths it has considered. It will also print the intersection
12661of them with the final unambiguous (possibly partial or even empty) code path
12662result.
12663
12664@item show debug entry-values
12665@kindex show debug entry-values
12666Show the current state of analysis messages printing for both frame argument
12667values at function entry and tail calls.
12668@end table
12669
12670The analysis messages for tail calls can for example show why the virtual tail
12671call frame for function @code{c} has not been recognized (due to the indirect
12672reference by variable @code{x}):
12673
12674@smallexample
12675static void __attribute__((noinline, noclone)) c (void);
12676void (*x) (void) = c;
12677static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
12678static void __attribute__((noinline, noclone)) c (void) @{ a (); @}
12679int main (void) @{ x (); return 0; @}
12680
216f72a1
JK
12681Breakpoint 1, DW_OP_entry_value resolving cannot find
12682DW_TAG_call_site 0x40039a in main
111c6489
JK
12683a () at t.c:3
126843 static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
12685(gdb) bt
12686#0 a () at t.c:3
12687#1 0x000000000040039a in main () at t.c:5
12688@end smallexample
12689
12690Another possibility is an ambiguous virtual tail call frames resolution:
12691
12692@smallexample
12693int i;
12694static void __attribute__((noinline, noclone)) f (void) @{ i++; @}
12695static void __attribute__((noinline, noclone)) e (void) @{ f (); @}
12696static void __attribute__((noinline, noclone)) d (void) @{ f (); @}
12697static void __attribute__((noinline, noclone)) c (void) @{ d (); @}
12698static void __attribute__((noinline, noclone)) b (void)
12699@{ if (i) c (); else e (); @}
12700static void __attribute__((noinline, noclone)) a (void) @{ b (); @}
12701int main (void) @{ a (); return 0; @}
12702
12703tailcall: initial: 0x4004d2(a) 0x4004ce(b) 0x4004b2(c) 0x4004a2(d)
12704tailcall: compare: 0x4004d2(a) 0x4004cc(b) 0x400492(e)
12705tailcall: reduced: 0x4004d2(a) |
12706(gdb) bt
12707#0 f () at t.c:2
12708#1 0x00000000004004d2 in a () at t.c:8
12709#2 0x0000000000400395 in main () at t.c:9
12710@end smallexample
12711
5048e516
JK
12712@set CALLSEQ1A @code{main@value{ARROW}a@value{ARROW}b@value{ARROW}c@value{ARROW}d@value{ARROW}f}
12713@set CALLSEQ2A @code{main@value{ARROW}a@value{ARROW}b@value{ARROW}e@value{ARROW}f}
12714
12715@c Convert CALLSEQ#A to CALLSEQ#B depending on HAVE_MAKEINFO_CLICK.
12716@ifset HAVE_MAKEINFO_CLICK
12717@set ARROW @click{}
12718@set CALLSEQ1B @clicksequence{@value{CALLSEQ1A}}
12719@set CALLSEQ2B @clicksequence{@value{CALLSEQ2A}}
12720@end ifset
12721@ifclear HAVE_MAKEINFO_CLICK
12722@set ARROW ->
12723@set CALLSEQ1B @value{CALLSEQ1A}
12724@set CALLSEQ2B @value{CALLSEQ2A}
12725@end ifclear
12726
12727Frames #0 and #2 are real, #1 is a virtual tail call frame.
12728The code can have possible execution paths @value{CALLSEQ1B} or
12729@value{CALLSEQ2B}, @value{GDBN} cannot find which one from the inferior state.
111c6489
JK
12730
12731@code{initial:} state shows some random possible calling sequence @value{GDBN}
12732has found. It then finds another possible calling sequcen - that one is
12733prefixed by @code{compare:}. The non-ambiguous intersection of these two is
12734printed as the @code{reduced:} calling sequence. That one could have many
12735futher @code{compare:} and @code{reduced:} statements as long as there remain
12736any non-ambiguous sequence entries.
12737
12738For the frame of function @code{b} in both cases there are different possible
12739@code{$pc} values (@code{0x4004cc} or @code{0x4004ce}), therefore this frame is
12740also ambigous. The only non-ambiguous frame is the one for function @code{a},
12741therefore this one is displayed to the user while the ambiguous frames are
12742omitted.
edb3359d 12743
e18b2753
JK
12744There can be also reasons why printing of frame argument values at function
12745entry may fail:
12746
12747@smallexample
12748int v;
12749static void __attribute__((noinline, noclone)) c (int i) @{ v++; @}
12750static void __attribute__((noinline, noclone)) a (int i);
12751static void __attribute__((noinline, noclone)) b (int i) @{ a (i); @}
12752static void __attribute__((noinline, noclone)) a (int i)
12753@{ if (i) b (i - 1); else c (0); @}
12754int main (void) @{ a (5); return 0; @}
12755
12756(gdb) bt
12757#0 c (i=i@@entry=0) at t.c:2
216f72a1 12758#1 0x0000000000400428 in a (DW_OP_entry_value resolving has found
e18b2753
JK
12759function "a" at 0x400420 can call itself via tail calls
12760i=<optimized out>) at t.c:6
12761#2 0x000000000040036e in main () at t.c:7
12762@end smallexample
12763
12764@value{GDBN} cannot find out from the inferior state if and how many times did
12765function @code{a} call itself (via function @code{b}) as these calls would be
12766tail calls. Such tail calls would modify thue @code{i} variable, therefore
12767@value{GDBN} cannot be sure the value it knows would be right - @value{GDBN}
12768prints @code{<optimized out>} instead.
12769
e2e0bcd1
JB
12770@node Macros
12771@chapter C Preprocessor Macros
12772
49efadf5 12773Some languages, such as C and C@t{++}, provide a way to define and invoke
e2e0bcd1
JB
12774``preprocessor macros'' which expand into strings of tokens.
12775@value{GDBN} can evaluate expressions containing macro invocations, show
12776the result of macro expansion, and show a macro's definition, including
12777where it was defined.
12778
12779You may need to compile your program specially to provide @value{GDBN}
12780with information about preprocessor macros. Most compilers do not
12781include macros in their debugging information, even when you compile
12782with the @option{-g} flag. @xref{Compilation}.
12783
12784A program may define a macro at one point, remove that definition later,
12785and then provide a different definition after that. Thus, at different
12786points in the program, a macro may have different definitions, or have
12787no definition at all. If there is a current stack frame, @value{GDBN}
12788uses the macros in scope at that frame's source code line. Otherwise,
12789@value{GDBN} uses the macros in scope at the current listing location;
12790see @ref{List}.
12791
e2e0bcd1
JB
12792Whenever @value{GDBN} evaluates an expression, it always expands any
12793macro invocations present in the expression. @value{GDBN} also provides
12794the following commands for working with macros explicitly.
12795
12796@table @code
12797
12798@kindex macro expand
12799@cindex macro expansion, showing the results of preprocessor
12800@cindex preprocessor macro expansion, showing the results of
12801@cindex expanding preprocessor macros
12802@item macro expand @var{expression}
12803@itemx macro exp @var{expression}
12804Show the results of expanding all preprocessor macro invocations in
12805@var{expression}. Since @value{GDBN} simply expands macros, but does
12806not parse the result, @var{expression} need not be a valid expression;
12807it can be any string of tokens.
12808
09d4efe1 12809@kindex macro exp1
e2e0bcd1
JB
12810@item macro expand-once @var{expression}
12811@itemx macro exp1 @var{expression}
4644b6e3 12812@cindex expand macro once
e2e0bcd1
JB
12813@i{(This command is not yet implemented.)} Show the results of
12814expanding those preprocessor macro invocations that appear explicitly in
12815@var{expression}. Macro invocations appearing in that expansion are
12816left unchanged. This command allows you to see the effect of a
12817particular macro more clearly, without being confused by further
12818expansions. Since @value{GDBN} simply expands macros, but does not
12819parse the result, @var{expression} need not be a valid expression; it
12820can be any string of tokens.
12821
475b0867 12822@kindex info macro
e2e0bcd1 12823@cindex macro definition, showing
9b158ba0 12824@cindex definition of a macro, showing
12825@cindex macros, from debug info
71eba9c2 12826@item info macro [-a|-all] [--] @var{macro}
12827Show the current definition or all definitions of the named @var{macro},
12828and describe the source location or compiler command-line where that
12829definition was established. The optional double dash is to signify the end of
12830argument processing and the beginning of @var{macro} for non C-like macros where
12831the macro may begin with a hyphen.
e2e0bcd1 12832
9b158ba0 12833@kindex info macros
629500fa 12834@item info macros @var{location}
9b158ba0 12835Show all macro definitions that are in effect at the location specified
629500fa 12836by @var{location}, and describe the source location or compiler
9b158ba0 12837command-line where those definitions were established.
12838
e2e0bcd1
JB
12839@kindex macro define
12840@cindex user-defined macros
12841@cindex defining macros interactively
12842@cindex macros, user-defined
12843@item macro define @var{macro} @var{replacement-list}
12844@itemx macro define @var{macro}(@var{arglist}) @var{replacement-list}
d7d9f01e
TT
12845Introduce a definition for a preprocessor macro named @var{macro},
12846invocations of which are replaced by the tokens given in
12847@var{replacement-list}. The first form of this command defines an
12848``object-like'' macro, which takes no arguments; the second form
12849defines a ``function-like'' macro, which takes the arguments given in
12850@var{arglist}.
12851
12852A definition introduced by this command is in scope in every
12853expression evaluated in @value{GDBN}, until it is removed with the
12854@code{macro undef} command, described below. The definition overrides
12855all definitions for @var{macro} present in the program being debugged,
12856as well as any previous user-supplied definition.
e2e0bcd1
JB
12857
12858@kindex macro undef
12859@item macro undef @var{macro}
d7d9f01e
TT
12860Remove any user-supplied definition for the macro named @var{macro}.
12861This command only affects definitions provided with the @code{macro
12862define} command, described above; it cannot remove definitions present
12863in the program being debugged.
e2e0bcd1 12864
09d4efe1
EZ
12865@kindex macro list
12866@item macro list
d7d9f01e 12867List all the macros defined using the @code{macro define} command.
e2e0bcd1
JB
12868@end table
12869
12870@cindex macros, example of debugging with
12871Here is a transcript showing the above commands in action. First, we
12872show our source files:
12873
12874@smallexample
12875$ cat sample.c
12876#include <stdio.h>
12877#include "sample.h"
12878
12879#define M 42
12880#define ADD(x) (M + x)
12881
12882main ()
12883@{
12884#define N 28
12885 printf ("Hello, world!\n");
12886#undef N
12887 printf ("We're so creative.\n");
12888#define N 1729
12889 printf ("Goodbye, world!\n");
12890@}
12891$ cat sample.h
12892#define Q <
12893$
12894@end smallexample
12895
e0f8f636
TT
12896Now, we compile the program using the @sc{gnu} C compiler,
12897@value{NGCC}. We pass the @option{-gdwarf-2}@footnote{This is the
12898minimum. Recent versions of @value{NGCC} support @option{-gdwarf-3}
12899and @option{-gdwarf-4}; we recommend always choosing the most recent
12900version of DWARF.} @emph{and} @option{-g3} flags to ensure the compiler
12901includes information about preprocessor macros in the debugging
e2e0bcd1
JB
12902information.
12903
12904@smallexample
12905$ gcc -gdwarf-2 -g3 sample.c -o sample
12906$
12907@end smallexample
12908
12909Now, we start @value{GDBN} on our sample program:
12910
12911@smallexample
12912$ gdb -nw sample
12913GNU gdb 2002-05-06-cvs
12914Copyright 2002 Free Software Foundation, Inc.
12915GDB is free software, @dots{}
f7dc1244 12916(@value{GDBP})
e2e0bcd1
JB
12917@end smallexample
12918
12919We can expand macros and examine their definitions, even when the
12920program is not running. @value{GDBN} uses the current listing position
12921to decide which macro definitions are in scope:
12922
12923@smallexample
f7dc1244 12924(@value{GDBP}) list main
e2e0bcd1
JB
129253
129264 #define M 42
129275 #define ADD(x) (M + x)
129286
129297 main ()
129308 @{
129319 #define N 28
1293210 printf ("Hello, world!\n");
1293311 #undef N
1293412 printf ("We're so creative.\n");
f7dc1244 12935(@value{GDBP}) info macro ADD
e2e0bcd1
JB
12936Defined at /home/jimb/gdb/macros/play/sample.c:5
12937#define ADD(x) (M + x)
f7dc1244 12938(@value{GDBP}) info macro Q
e2e0bcd1
JB
12939Defined at /home/jimb/gdb/macros/play/sample.h:1
12940 included at /home/jimb/gdb/macros/play/sample.c:2
12941#define Q <
f7dc1244 12942(@value{GDBP}) macro expand ADD(1)
e2e0bcd1 12943expands to: (42 + 1)
f7dc1244 12944(@value{GDBP}) macro expand-once ADD(1)
e2e0bcd1 12945expands to: once (M + 1)
f7dc1244 12946(@value{GDBP})
e2e0bcd1
JB
12947@end smallexample
12948
d7d9f01e 12949In the example above, note that @code{macro expand-once} expands only
e2e0bcd1
JB
12950the macro invocation explicit in the original text --- the invocation of
12951@code{ADD} --- but does not expand the invocation of the macro @code{M},
12952which was introduced by @code{ADD}.
12953
3f94c067
BW
12954Once the program is running, @value{GDBN} uses the macro definitions in
12955force at the source line of the current stack frame:
e2e0bcd1
JB
12956
12957@smallexample
f7dc1244 12958(@value{GDBP}) break main
e2e0bcd1 12959Breakpoint 1 at 0x8048370: file sample.c, line 10.
f7dc1244 12960(@value{GDBP}) run
b383017d 12961Starting program: /home/jimb/gdb/macros/play/sample
e2e0bcd1
JB
12962
12963Breakpoint 1, main () at sample.c:10
1296410 printf ("Hello, world!\n");
f7dc1244 12965(@value{GDBP})
e2e0bcd1
JB
12966@end smallexample
12967
12968At line 10, the definition of the macro @code{N} at line 9 is in force:
12969
12970@smallexample
f7dc1244 12971(@value{GDBP}) info macro N
e2e0bcd1
JB
12972Defined at /home/jimb/gdb/macros/play/sample.c:9
12973#define N 28
f7dc1244 12974(@value{GDBP}) macro expand N Q M
e2e0bcd1 12975expands to: 28 < 42
f7dc1244 12976(@value{GDBP}) print N Q M
e2e0bcd1 12977$1 = 1
f7dc1244 12978(@value{GDBP})
e2e0bcd1
JB
12979@end smallexample
12980
12981As we step over directives that remove @code{N}'s definition, and then
12982give it a new definition, @value{GDBN} finds the definition (or lack
12983thereof) in force at each point:
12984
12985@smallexample
f7dc1244 12986(@value{GDBP}) next
e2e0bcd1
JB
12987Hello, world!
1298812 printf ("We're so creative.\n");
f7dc1244 12989(@value{GDBP}) info macro N
e2e0bcd1
JB
12990The symbol `N' has no definition as a C/C++ preprocessor macro
12991at /home/jimb/gdb/macros/play/sample.c:12
f7dc1244 12992(@value{GDBP}) next
e2e0bcd1
JB
12993We're so creative.
1299414 printf ("Goodbye, world!\n");
f7dc1244 12995(@value{GDBP}) info macro N
e2e0bcd1
JB
12996Defined at /home/jimb/gdb/macros/play/sample.c:13
12997#define N 1729
f7dc1244 12998(@value{GDBP}) macro expand N Q M
e2e0bcd1 12999expands to: 1729 < 42
f7dc1244 13000(@value{GDBP}) print N Q M
e2e0bcd1 13001$2 = 0
f7dc1244 13002(@value{GDBP})
e2e0bcd1
JB
13003@end smallexample
13004
484086b7
JK
13005In addition to source files, macros can be defined on the compilation command
13006line using the @option{-D@var{name}=@var{value}} syntax. For macros defined in
13007such a way, @value{GDBN} displays the location of their definition as line zero
13008of the source file submitted to the compiler.
13009
13010@smallexample
13011(@value{GDBP}) info macro __STDC__
13012Defined at /home/jimb/gdb/macros/play/sample.c:0
13013-D__STDC__=1
13014(@value{GDBP})
13015@end smallexample
13016
e2e0bcd1 13017
b37052ae
EZ
13018@node Tracepoints
13019@chapter Tracepoints
13020@c This chapter is based on the documentation written by Michael
13021@c Snyder, David Taylor, Jim Blandy, and Elena Zannoni.
13022
13023@cindex tracepoints
13024In some applications, it is not feasible for the debugger to interrupt
13025the program's execution long enough for the developer to learn
13026anything helpful about its behavior. If the program's correctness
13027depends on its real-time behavior, delays introduced by a debugger
13028might cause the program to change its behavior drastically, or perhaps
13029fail, even when the code itself is correct. It is useful to be able
13030to observe the program's behavior without interrupting it.
13031
13032Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can
13033specify locations in the program, called @dfn{tracepoints}, and
13034arbitrary expressions to evaluate when those tracepoints are reached.
13035Later, using the @code{tfind} command, you can examine the values
13036those expressions had when the program hit the tracepoints. The
13037expressions may also denote objects in memory---structures or arrays,
13038for example---whose values @value{GDBN} should record; while visiting
13039a particular tracepoint, you may inspect those objects as if they were
13040in memory at that moment. However, because @value{GDBN} records these
13041values without interacting with you, it can do so quickly and
13042unobtrusively, hopefully not disturbing the program's behavior.
13043
13044The tracepoint facility is currently available only for remote
9d29849a
JB
13045targets. @xref{Targets}. In addition, your remote target must know
13046how to collect trace data. This functionality is implemented in the
13047remote stub; however, none of the stubs distributed with @value{GDBN}
13048support tracepoints as of this writing. The format of the remote
13049packets used to implement tracepoints are described in @ref{Tracepoint
13050Packets}.
b37052ae 13051
00bf0b85
SS
13052It is also possible to get trace data from a file, in a manner reminiscent
13053of corefiles; you specify the filename, and use @code{tfind} to search
13054through the file. @xref{Trace Files}, for more details.
13055
b37052ae
EZ
13056This chapter describes the tracepoint commands and features.
13057
13058@menu
b383017d
RM
13059* Set Tracepoints::
13060* Analyze Collected Data::
13061* Tracepoint Variables::
00bf0b85 13062* Trace Files::
b37052ae
EZ
13063@end menu
13064
13065@node Set Tracepoints
13066@section Commands to Set Tracepoints
13067
13068Before running such a @dfn{trace experiment}, an arbitrary number of
1042e4c0
SS
13069tracepoints can be set. A tracepoint is actually a special type of
13070breakpoint (@pxref{Set Breaks}), so you can manipulate it using
13071standard breakpoint commands. For instance, as with breakpoints,
13072tracepoint numbers are successive integers starting from one, and many
13073of the commands associated with tracepoints take the tracepoint number
13074as their argument, to identify which tracepoint to work on.
b37052ae
EZ
13075
13076For each tracepoint, you can specify, in advance, some arbitrary set
13077of data that you want the target to collect in the trace buffer when
13078it hits that tracepoint. The collected data can include registers,
13079local variables, or global data. Later, you can use @value{GDBN}
13080commands to examine the values these data had at the time the
13081tracepoint was hit.
13082
7d13fe92
SS
13083Tracepoints do not support every breakpoint feature. Ignore counts on
13084tracepoints have no effect, and tracepoints cannot run @value{GDBN}
13085commands when they are hit. Tracepoints may not be thread-specific
13086either.
1042e4c0 13087
7a697b8d
SS
13088@cindex fast tracepoints
13089Some targets may support @dfn{fast tracepoints}, which are inserted in
13090a different way (such as with a jump instead of a trap), that is
13091faster but possibly restricted in where they may be installed.
13092
0fb4aa4b
PA
13093@cindex static tracepoints
13094@cindex markers, static tracepoints
13095@cindex probing markers, static tracepoints
13096Regular and fast tracepoints are dynamic tracing facilities, meaning
13097that they can be used to insert tracepoints at (almost) any location
13098in the target. Some targets may also support controlling @dfn{static
13099tracepoints} from @value{GDBN}. With static tracing, a set of
13100instrumentation points, also known as @dfn{markers}, are embedded in
13101the target program, and can be activated or deactivated by name or
13102address. These are usually placed at locations which facilitate
13103investigating what the target is actually doing. @value{GDBN}'s
13104support for static tracing includes being able to list instrumentation
13105points, and attach them with @value{GDBN} defined high level
13106tracepoints that expose the whole range of convenience of
8786b2bd 13107@value{GDBN}'s tracepoints support. Namely, support for collecting
0fb4aa4b
PA
13108registers values and values of global or local (to the instrumentation
13109point) variables; tracepoint conditions and trace state variables.
13110The act of installing a @value{GDBN} static tracepoint on an
13111instrumentation point, or marker, is referred to as @dfn{probing} a
13112static tracepoint marker.
13113
fa593d66
PA
13114@code{gdbserver} supports tracepoints on some target systems.
13115@xref{Server,,Tracepoints support in @code{gdbserver}}.
13116
b37052ae
EZ
13117This section describes commands to set tracepoints and associated
13118conditions and actions.
13119
13120@menu
b383017d
RM
13121* Create and Delete Tracepoints::
13122* Enable and Disable Tracepoints::
13123* Tracepoint Passcounts::
782b2b07 13124* Tracepoint Conditions::
f61e138d 13125* Trace State Variables::
b383017d
RM
13126* Tracepoint Actions::
13127* Listing Tracepoints::
0fb4aa4b 13128* Listing Static Tracepoint Markers::
79a6e687 13129* Starting and Stopping Trace Experiments::
c9429232 13130* Tracepoint Restrictions::
b37052ae
EZ
13131@end menu
13132
13133@node Create and Delete Tracepoints
13134@subsection Create and Delete Tracepoints
13135
13136@table @code
13137@cindex set tracepoint
13138@kindex trace
1042e4c0 13139@item trace @var{location}
b37052ae 13140The @code{trace} command is very similar to the @code{break} command.
629500fa
KS
13141Its argument @var{location} can be any valid location.
13142@xref{Specify Location}. The @code{trace} command defines a tracepoint,
13143which is a point in the target program where the debugger will briefly stop,
13144collect some data, and then allow the program to continue. Setting a tracepoint
13145or changing its actions takes effect immediately if the remote stub
1e4d1764
YQ
13146supports the @samp{InstallInTrace} feature (@pxref{install tracepoint
13147in tracing}).
13148If remote stub doesn't support the @samp{InstallInTrace} feature, all
13149these changes don't take effect until the next @code{tstart}
1042e4c0 13150command, and once a trace experiment is running, further changes will
bfccc43c
YQ
13151not have any effect until the next trace experiment starts. In addition,
13152@value{GDBN} supports @dfn{pending tracepoints}---tracepoints whose
13153address is not yet resolved. (This is similar to pending breakpoints.)
13154Pending tracepoints are not downloaded to the target and not installed
13155until they are resolved. The resolution of pending tracepoints requires
13156@value{GDBN} support---when debugging with the remote target, and
13157@value{GDBN} disconnects from the remote stub (@pxref{disconnected
13158tracing}), pending tracepoints can not be resolved (and downloaded to
13159the remote stub) while @value{GDBN} is disconnected.
b37052ae
EZ
13160
13161Here are some examples of using the @code{trace} command:
13162
13163@smallexample
13164(@value{GDBP}) @b{trace foo.c:121} // a source file and line number
13165
13166(@value{GDBP}) @b{trace +2} // 2 lines forward
13167
13168(@value{GDBP}) @b{trace my_function} // first source line of function
13169
13170(@value{GDBP}) @b{trace *my_function} // EXACT start address of function
13171
13172(@value{GDBP}) @b{trace *0x2117c4} // an address
13173@end smallexample
13174
13175@noindent
13176You can abbreviate @code{trace} as @code{tr}.
13177
782b2b07
SS
13178@item trace @var{location} if @var{cond}
13179Set a tracepoint with condition @var{cond}; evaluate the expression
13180@var{cond} each time the tracepoint is reached, and collect data only
13181if the value is nonzero---that is, if @var{cond} evaluates as true.
13182@xref{Tracepoint Conditions, ,Tracepoint Conditions}, for more
13183information on tracepoint conditions.
13184
7a697b8d
SS
13185@item ftrace @var{location} [ if @var{cond} ]
13186@cindex set fast tracepoint
74c761c1 13187@cindex fast tracepoints, setting
7a697b8d
SS
13188@kindex ftrace
13189The @code{ftrace} command sets a fast tracepoint. For targets that
13190support them, fast tracepoints will use a more efficient but possibly
13191less general technique to trigger data collection, such as a jump
13192instruction instead of a trap, or some sort of hardware support. It
13193may not be possible to create a fast tracepoint at the desired
13194location, in which case the command will exit with an explanatory
13195message.
13196
13197@value{GDBN} handles arguments to @code{ftrace} exactly as for
13198@code{trace}.
13199
405f8e94
SS
13200On 32-bit x86-architecture systems, fast tracepoints normally need to
13201be placed at an instruction that is 5 bytes or longer, but can be
13202placed at 4-byte instructions if the low 64K of memory of the target
13203program is available to install trampolines. Some Unix-type systems,
13204such as @sc{gnu}/Linux, exclude low addresses from the program's
13205address space; but for instance with the Linux kernel it is possible
13206to let @value{GDBN} use this area by doing a @command{sysctl} command
13207to set the @code{mmap_min_addr} kernel parameter, as in
13208
13209@example
13210sudo sysctl -w vm.mmap_min_addr=32768
13211@end example
13212
13213@noindent
13214which sets the low address to 32K, which leaves plenty of room for
13215trampolines. The minimum address should be set to a page boundary.
13216
0fb4aa4b 13217@item strace @var{location} [ if @var{cond} ]
74c761c1
PA
13218@cindex set static tracepoint
13219@cindex static tracepoints, setting
13220@cindex probe static tracepoint marker
0fb4aa4b
PA
13221@kindex strace
13222The @code{strace} command sets a static tracepoint. For targets that
13223support it, setting a static tracepoint probes a static
13224instrumentation point, or marker, found at @var{location}. It may not
13225be possible to set a static tracepoint at the desired location, in
13226which case the command will exit with an explanatory message.
13227
13228@value{GDBN} handles arguments to @code{strace} exactly as for
13229@code{trace}, with the addition that the user can also specify
13230@code{-m @var{marker}} as @var{location}. This probes the marker
13231identified by the @var{marker} string identifier. This identifier
13232depends on the static tracepoint backend library your program is
13233using. You can find all the marker identifiers in the @samp{ID} field
13234of the @code{info static-tracepoint-markers} command output.
13235@xref{Listing Static Tracepoint Markers,,Listing Static Tracepoint
13236Markers}. For example, in the following small program using the UST
13237tracing engine:
13238
13239@smallexample
13240main ()
13241@{
13242 trace_mark(ust, bar33, "str %s", "FOOBAZ");
13243@}
13244@end smallexample
13245
13246@noindent
13247the marker id is composed of joining the first two arguments to the
13248@code{trace_mark} call with a slash, which translates to:
13249
13250@smallexample
13251(@value{GDBP}) info static-tracepoint-markers
13252Cnt Enb ID Address What
132531 n ust/bar33 0x0000000000400ddc in main at stexample.c:22
13254 Data: "str %s"
13255[etc...]
13256@end smallexample
13257
13258@noindent
13259so you may probe the marker above with:
13260
13261@smallexample
13262(@value{GDBP}) strace -m ust/bar33
13263@end smallexample
13264
13265Static tracepoints accept an extra collect action --- @code{collect
13266$_sdata}. This collects arbitrary user data passed in the probe point
13267call to the tracing library. In the UST example above, you'll see
13268that the third argument to @code{trace_mark} is a printf-like format
13269string. The user data is then the result of running that formating
13270string against the following arguments. Note that @code{info
13271static-tracepoint-markers} command output lists that format string in
13272the @samp{Data:} field.
13273
13274You can inspect this data when analyzing the trace buffer, by printing
13275the $_sdata variable like any other variable available to
13276@value{GDBN}. @xref{Tracepoint Actions,,Tracepoint Action Lists}.
13277
b37052ae
EZ
13278@vindex $tpnum
13279@cindex last tracepoint number
13280@cindex recent tracepoint number
13281@cindex tracepoint number
13282The convenience variable @code{$tpnum} records the tracepoint number
13283of the most recently set tracepoint.
13284
13285@kindex delete tracepoint
13286@cindex tracepoint deletion
13287@item delete tracepoint @r{[}@var{num}@r{]}
13288Permanently delete one or more tracepoints. With no argument, the
1042e4c0
SS
13289default is to delete all tracepoints. Note that the regular
13290@code{delete} command can remove tracepoints also.
b37052ae
EZ
13291
13292Examples:
13293
13294@smallexample
13295(@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints
13296
13297(@value{GDBP}) @b{delete trace} // remove all tracepoints
13298@end smallexample
13299
13300@noindent
13301You can abbreviate this command as @code{del tr}.
13302@end table
13303
13304@node Enable and Disable Tracepoints
13305@subsection Enable and Disable Tracepoints
13306
1042e4c0
SS
13307These commands are deprecated; they are equivalent to plain @code{disable} and @code{enable}.
13308
b37052ae
EZ
13309@table @code
13310@kindex disable tracepoint
13311@item disable tracepoint @r{[}@var{num}@r{]}
13312Disable tracepoint @var{num}, or all tracepoints if no argument
13313@var{num} is given. A disabled tracepoint will have no effect during
d248b706 13314a trace experiment, but it is not forgotten. You can re-enable
b37052ae 13315a disabled tracepoint using the @code{enable tracepoint} command.
d248b706
KY
13316If the command is issued during a trace experiment and the debug target
13317has support for disabling tracepoints during a trace experiment, then the
13318change will be effective immediately. Otherwise, it will be applied to the
13319next trace experiment.
b37052ae
EZ
13320
13321@kindex enable tracepoint
13322@item enable tracepoint @r{[}@var{num}@r{]}
d248b706
KY
13323Enable tracepoint @var{num}, or all tracepoints. If this command is
13324issued during a trace experiment and the debug target supports enabling
13325tracepoints during a trace experiment, then the enabled tracepoints will
13326become effective immediately. Otherwise, they will become effective the
13327next time a trace experiment is run.
b37052ae
EZ
13328@end table
13329
13330@node Tracepoint Passcounts
13331@subsection Tracepoint Passcounts
13332
13333@table @code
13334@kindex passcount
13335@cindex tracepoint pass count
13336@item passcount @r{[}@var{n} @r{[}@var{num}@r{]]}
13337Set the @dfn{passcount} of a tracepoint. The passcount is a way to
13338automatically stop a trace experiment. If a tracepoint's passcount is
13339@var{n}, then the trace experiment will be automatically stopped on
13340the @var{n}'th time that tracepoint is hit. If the tracepoint number
13341@var{num} is not specified, the @code{passcount} command sets the
13342passcount of the most recently defined tracepoint. If no passcount is
13343given, the trace experiment will run until stopped explicitly by the
13344user.
13345
13346Examples:
13347
13348@smallexample
b383017d 13349(@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of
6826cf00 13350@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2}
b37052ae
EZ
13351
13352(@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the
6826cf00 13353@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.}
b37052ae
EZ
13354(@value{GDBP}) @b{trace foo}
13355(@value{GDBP}) @b{pass 3}
13356(@value{GDBP}) @b{trace bar}
13357(@value{GDBP}) @b{pass 2}
13358(@value{GDBP}) @b{trace baz}
13359(@value{GDBP}) @b{pass 1} // Stop tracing when foo has been
6826cf00
EZ
13360@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has}
13361@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times}
13362@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.}
b37052ae
EZ
13363@end smallexample
13364@end table
13365
782b2b07
SS
13366@node Tracepoint Conditions
13367@subsection Tracepoint Conditions
13368@cindex conditional tracepoints
13369@cindex tracepoint conditions
13370
13371The simplest sort of tracepoint collects data every time your program
13372reaches a specified place. You can also specify a @dfn{condition} for
13373a tracepoint. A condition is just a Boolean expression in your
13374programming language (@pxref{Expressions, ,Expressions}). A
13375tracepoint with a condition evaluates the expression each time your
13376program reaches it, and data collection happens only if the condition
13377is true.
13378
13379Tracepoint conditions can be specified when a tracepoint is set, by
13380using @samp{if} in the arguments to the @code{trace} command.
13381@xref{Create and Delete Tracepoints, ,Setting Tracepoints}. They can
13382also be set or changed at any time with the @code{condition} command,
13383just as with breakpoints.
13384
13385Unlike breakpoint conditions, @value{GDBN} does not actually evaluate
13386the conditional expression itself. Instead, @value{GDBN} encodes the
6dcd5565 13387expression into an agent expression (@pxref{Agent Expressions})
782b2b07
SS
13388suitable for execution on the target, independently of @value{GDBN}.
13389Global variables become raw memory locations, locals become stack
13390accesses, and so forth.
13391
13392For instance, suppose you have a function that is usually called
13393frequently, but should not be called after an error has occurred. You
13394could use the following tracepoint command to collect data about calls
13395of that function that happen while the error code is propagating
13396through the program; an unconditional tracepoint could end up
13397collecting thousands of useless trace frames that you would have to
13398search through.
13399
13400@smallexample
13401(@value{GDBP}) @kbd{trace normal_operation if errcode > 0}
13402@end smallexample
13403
f61e138d
SS
13404@node Trace State Variables
13405@subsection Trace State Variables
13406@cindex trace state variables
13407
13408A @dfn{trace state variable} is a special type of variable that is
13409created and managed by target-side code. The syntax is the same as
13410that for GDB's convenience variables (a string prefixed with ``$''),
13411but they are stored on the target. They must be created explicitly,
13412using a @code{tvariable} command. They are always 64-bit signed
13413integers.
13414
13415Trace state variables are remembered by @value{GDBN}, and downloaded
13416to the target along with tracepoint information when the trace
13417experiment starts. There are no intrinsic limits on the number of
13418trace state variables, beyond memory limitations of the target.
13419
13420@cindex convenience variables, and trace state variables
13421Although trace state variables are managed by the target, you can use
13422them in print commands and expressions as if they were convenience
13423variables; @value{GDBN} will get the current value from the target
13424while the trace experiment is running. Trace state variables share
13425the same namespace as other ``$'' variables, which means that you
13426cannot have trace state variables with names like @code{$23} or
13427@code{$pc}, nor can you have a trace state variable and a convenience
13428variable with the same name.
13429
13430@table @code
13431
13432@item tvariable $@var{name} [ = @var{expression} ]
13433@kindex tvariable
13434The @code{tvariable} command creates a new trace state variable named
13435@code{$@var{name}}, and optionally gives it an initial value of
697aa1b7 13436@var{expression}. The @var{expression} is evaluated when this command is
f61e138d
SS
13437entered; the result will be converted to an integer if possible,
13438otherwise @value{GDBN} will report an error. A subsequent
13439@code{tvariable} command specifying the same name does not create a
13440variable, but instead assigns the supplied initial value to the
13441existing variable of that name, overwriting any previous initial
13442value. The default initial value is 0.
13443
13444@item info tvariables
13445@kindex info tvariables
13446List all the trace state variables along with their initial values.
13447Their current values may also be displayed, if the trace experiment is
13448currently running.
13449
13450@item delete tvariable @r{[} $@var{name} @dots{} @r{]}
13451@kindex delete tvariable
13452Delete the given trace state variables, or all of them if no arguments
13453are specified.
13454
13455@end table
13456
b37052ae
EZ
13457@node Tracepoint Actions
13458@subsection Tracepoint Action Lists
13459
13460@table @code
13461@kindex actions
13462@cindex tracepoint actions
13463@item actions @r{[}@var{num}@r{]}
13464This command will prompt for a list of actions to be taken when the
13465tracepoint is hit. If the tracepoint number @var{num} is not
13466specified, this command sets the actions for the one that was most
13467recently defined (so that you can define a tracepoint and then say
13468@code{actions} without bothering about its number). You specify the
13469actions themselves on the following lines, one action at a time, and
13470terminate the actions list with a line containing just @code{end}. So
7d13fe92 13471far, the only defined actions are @code{collect}, @code{teval}, and
b37052ae
EZ
13472@code{while-stepping}.
13473
5a9351ae
SS
13474@code{actions} is actually equivalent to @code{commands} (@pxref{Break
13475Commands, ,Breakpoint Command Lists}), except that only the defined
13476actions are allowed; any other @value{GDBN} command is rejected.
13477
b37052ae
EZ
13478@cindex remove actions from a tracepoint
13479To remove all actions from a tracepoint, type @samp{actions @var{num}}
13480and follow it immediately with @samp{end}.
13481
13482@smallexample
13483(@value{GDBP}) @b{collect @var{data}} // collect some data
13484
6826cf00 13485(@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data
b37052ae 13486
6826cf00 13487(@value{GDBP}) @b{end} // signals the end of actions.
b37052ae
EZ
13488@end smallexample
13489
13490In the following example, the action list begins with @code{collect}
13491commands indicating the things to be collected when the tracepoint is
13492hit. Then, in order to single-step and collect additional data
13493following the tracepoint, a @code{while-stepping} command is used,
7d13fe92
SS
13494followed by the list of things to be collected after each step in a
13495sequence of single steps. The @code{while-stepping} command is
13496terminated by its own separate @code{end} command. Lastly, the action
13497list is terminated by an @code{end} command.
b37052ae
EZ
13498
13499@smallexample
13500(@value{GDBP}) @b{trace foo}
13501(@value{GDBP}) @b{actions}
13502Enter actions for tracepoint 1, one per line:
13503> collect bar,baz
13504> collect $regs
13505> while-stepping 12
5a9351ae 13506 > collect $pc, arr[i]
b37052ae
EZ
13507 > end
13508end
13509@end smallexample
13510
13511@kindex collect @r{(tracepoints)}
3065dfb6 13512@item collect@r{[}/@var{mods}@r{]} @var{expr1}, @var{expr2}, @dots{}
b37052ae
EZ
13513Collect values of the given expressions when the tracepoint is hit.
13514This command accepts a comma-separated list of any valid expressions.
13515In addition to global, static, or local variables, the following
13516special arguments are supported:
13517
13518@table @code
13519@item $regs
0fb4aa4b 13520Collect all registers.
b37052ae
EZ
13521
13522@item $args
0fb4aa4b 13523Collect all function arguments.
b37052ae
EZ
13524
13525@item $locals
0fb4aa4b
PA
13526Collect all local variables.
13527
6710bf39
SS
13528@item $_ret
13529Collect the return address. This is helpful if you want to see more
13530of a backtrace.
13531
2a60e18f 13532@emph{Note:} The return address location can not always be reliably
45fa2529
PA
13533determined up front, and the wrong address / registers may end up
13534collected instead. On some architectures the reliability is higher
13535for tracepoints at function entry, while on others it's the opposite.
13536When this happens, backtracing will stop because the return address is
13537found unavailable (unless another collect rule happened to match it).
13538
62e5f89c
SDJ
13539@item $_probe_argc
13540Collects the number of arguments from the static probe at which the
13541tracepoint is located.
13542@xref{Static Probe Points}.
13543
13544@item $_probe_arg@var{n}
13545@var{n} is an integer between 0 and 11. Collects the @var{n}th argument
13546from the static probe at which the tracepoint is located.
13547@xref{Static Probe Points}.
13548
0fb4aa4b
PA
13549@item $_sdata
13550@vindex $_sdata@r{, collect}
13551Collect static tracepoint marker specific data. Only available for
13552static tracepoints. @xref{Tracepoint Actions,,Tracepoint Action
13553Lists}. On the UST static tracepoints library backend, an
13554instrumentation point resembles a @code{printf} function call. The
13555tracing library is able to collect user specified data formatted to a
13556character string using the format provided by the programmer that
13557instrumented the program. Other backends have similar mechanisms.
13558Here's an example of a UST marker call:
13559
13560@smallexample
13561 const char master_name[] = "$your_name";
13562 trace_mark(channel1, marker1, "hello %s", master_name)
13563@end smallexample
13564
13565In this case, collecting @code{$_sdata} collects the string
13566@samp{hello $yourname}. When analyzing the trace buffer, you can
13567inspect @samp{$_sdata} like any other variable available to
13568@value{GDBN}.
b37052ae
EZ
13569@end table
13570
13571You can give several consecutive @code{collect} commands, each one
13572with a single argument, or one @code{collect} command with several
5a9351ae 13573arguments separated by commas; the effect is the same.
b37052ae 13574
3065dfb6
SS
13575The optional @var{mods} changes the usual handling of the arguments.
13576@code{s} requests that pointers to chars be handled as strings, in
13577particular collecting the contents of the memory being pointed at, up
13578to the first zero. The upper bound is by default the value of the
13579@code{print elements} variable; if @code{s} is followed by a decimal
13580number, that is the upper bound instead. So for instance
13581@samp{collect/s25 mystr} collects as many as 25 characters at
13582@samp{mystr}.
13583
f5c37c66
EZ
13584The command @code{info scope} (@pxref{Symbols, info scope}) is
13585particularly useful for figuring out what data to collect.
13586
6da95a67
SS
13587@kindex teval @r{(tracepoints)}
13588@item teval @var{expr1}, @var{expr2}, @dots{}
13589Evaluate the given expressions when the tracepoint is hit. This
13590command accepts a comma-separated list of expressions. The results
13591are discarded, so this is mainly useful for assigning values to trace
13592state variables (@pxref{Trace State Variables}) without adding those
13593values to the trace buffer, as would be the case if the @code{collect}
13594action were used.
13595
b37052ae
EZ
13596@kindex while-stepping @r{(tracepoints)}
13597@item while-stepping @var{n}
c9429232 13598Perform @var{n} single-step instruction traces after the tracepoint,
7d13fe92 13599collecting new data after each step. The @code{while-stepping}
c9429232
SS
13600command is followed by the list of what to collect while stepping
13601(followed by its own @code{end} command):
b37052ae
EZ
13602
13603@smallexample
13604> while-stepping 12
13605 > collect $regs, myglobal
13606 > end
13607>
13608@end smallexample
13609
13610@noindent
7d13fe92
SS
13611Note that @code{$pc} is not automatically collected by
13612@code{while-stepping}; you need to explicitly collect that register if
13613you need it. You may abbreviate @code{while-stepping} as @code{ws} or
b37052ae 13614@code{stepping}.
236f1d4d
SS
13615
13616@item set default-collect @var{expr1}, @var{expr2}, @dots{}
13617@kindex set default-collect
13618@cindex default collection action
13619This variable is a list of expressions to collect at each tracepoint
13620hit. It is effectively an additional @code{collect} action prepended
13621to every tracepoint action list. The expressions are parsed
13622individually for each tracepoint, so for instance a variable named
13623@code{xyz} may be interpreted as a global for one tracepoint, and a
13624local for another, as appropriate to the tracepoint's location.
13625
13626@item show default-collect
13627@kindex show default-collect
13628Show the list of expressions that are collected by default at each
13629tracepoint hit.
13630
b37052ae
EZ
13631@end table
13632
13633@node Listing Tracepoints
13634@subsection Listing Tracepoints
13635
13636@table @code
e5a67952
MS
13637@kindex info tracepoints @r{[}@var{n}@dots{}@r{]}
13638@kindex info tp @r{[}@var{n}@dots{}@r{]}
b37052ae 13639@cindex information about tracepoints
e5a67952 13640@item info tracepoints @r{[}@var{num}@dots{}@r{]}
1042e4c0
SS
13641Display information about the tracepoint @var{num}. If you don't
13642specify a tracepoint number, displays information about all the
13643tracepoints defined so far. The format is similar to that used for
13644@code{info breakpoints}; in fact, @code{info tracepoints} is the same
13645command, simply restricting itself to tracepoints.
13646
13647A tracepoint's listing may include additional information specific to
13648tracing:
b37052ae
EZ
13649
13650@itemize @bullet
13651@item
b37052ae 13652its passcount as given by the @code{passcount @var{n}} command
f2a8bc8a
YQ
13653
13654@item
13655the state about installed on target of each location
b37052ae
EZ
13656@end itemize
13657
13658@smallexample
13659(@value{GDBP}) @b{info trace}
1042e4c0
SS
13660Num Type Disp Enb Address What
136611 tracepoint keep y 0x0804ab57 in foo() at main.cxx:7
5a9351ae
SS
13662 while-stepping 20
13663 collect globfoo, $regs
13664 end
13665 collect globfoo2
13666 end
1042e4c0 13667 pass count 1200
f2a8bc8a
YQ
136682 tracepoint keep y <MULTIPLE>
13669 collect $eip
136702.1 y 0x0804859c in func4 at change-loc.h:35
13671 installed on target
136722.2 y 0xb7ffc480 in func4 at change-loc.h:35
13673 installed on target
136742.3 y <PENDING> set_tracepoint
136753 tracepoint keep y 0x080485b1 in foo at change-loc.c:29
13676 not installed on target
b37052ae
EZ
13677(@value{GDBP})
13678@end smallexample
13679
13680@noindent
13681This command can be abbreviated @code{info tp}.
13682@end table
13683
0fb4aa4b
PA
13684@node Listing Static Tracepoint Markers
13685@subsection Listing Static Tracepoint Markers
13686
13687@table @code
13688@kindex info static-tracepoint-markers
13689@cindex information about static tracepoint markers
13690@item info static-tracepoint-markers
13691Display information about all static tracepoint markers defined in the
13692program.
13693
13694For each marker, the following columns are printed:
13695
13696@table @emph
13697@item Count
13698An incrementing counter, output to help readability. This is not a
13699stable identifier.
13700@item ID
13701The marker ID, as reported by the target.
13702@item Enabled or Disabled
13703Probed markers are tagged with @samp{y}. @samp{n} identifies marks
13704that are not enabled.
13705@item Address
13706Where the marker is in your program, as a memory address.
13707@item What
13708Where the marker is in the source for your program, as a file and line
13709number. If the debug information included in the program does not
13710allow @value{GDBN} to locate the source of the marker, this column
13711will be left blank.
13712@end table
13713
13714@noindent
13715In addition, the following information may be printed for each marker:
13716
13717@table @emph
13718@item Data
13719User data passed to the tracing library by the marker call. In the
13720UST backend, this is the format string passed as argument to the
13721marker call.
13722@item Static tracepoints probing the marker
13723The list of static tracepoints attached to the marker.
13724@end table
13725
13726@smallexample
13727(@value{GDBP}) info static-tracepoint-markers
13728Cnt ID Enb Address What
137291 ust/bar2 y 0x0000000000400e1a in main at stexample.c:25
13730 Data: number1 %d number2 %d
13731 Probed by static tracepoints: #2
137322 ust/bar33 n 0x0000000000400c87 in main at stexample.c:24
13733 Data: str %s
13734(@value{GDBP})
13735@end smallexample
13736@end table
13737
79a6e687
BW
13738@node Starting and Stopping Trace Experiments
13739@subsection Starting and Stopping Trace Experiments
b37052ae
EZ
13740
13741@table @code
f196051f 13742@kindex tstart [ @var{notes} ]
b37052ae
EZ
13743@cindex start a new trace experiment
13744@cindex collected data discarded
13745@item tstart
f196051f
SS
13746This command starts the trace experiment, and begins collecting data.
13747It has the side effect of discarding all the data collected in the
13748trace buffer during the previous trace experiment. If any arguments
13749are supplied, they are taken as a note and stored with the trace
13750experiment's state. The notes may be arbitrary text, and are
13751especially useful with disconnected tracing in a multi-user context;
13752the notes can explain what the trace is doing, supply user contact
13753information, and so forth.
13754
13755@kindex tstop [ @var{notes} ]
b37052ae
EZ
13756@cindex stop a running trace experiment
13757@item tstop
f196051f
SS
13758This command stops the trace experiment. If any arguments are
13759supplied, they are recorded with the experiment as a note. This is
13760useful if you are stopping a trace started by someone else, for
13761instance if the trace is interfering with the system's behavior and
13762needs to be stopped quickly.
b37052ae 13763
68c71a2e 13764@strong{Note}: a trace experiment and data collection may stop
b37052ae
EZ
13765automatically if any tracepoint's passcount is reached
13766(@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full.
13767
13768@kindex tstatus
13769@cindex status of trace data collection
13770@cindex trace experiment, status of
13771@item tstatus
13772This command displays the status of the current trace data
13773collection.
13774@end table
13775
13776Here is an example of the commands we described so far:
13777
13778@smallexample
13779(@value{GDBP}) @b{trace gdb_c_test}
13780(@value{GDBP}) @b{actions}
13781Enter actions for tracepoint #1, one per line.
13782> collect $regs,$locals,$args
13783> while-stepping 11
13784 > collect $regs
13785 > end
13786> end
13787(@value{GDBP}) @b{tstart}
13788 [time passes @dots{}]
13789(@value{GDBP}) @b{tstop}
13790@end smallexample
13791
03f2bd59 13792@anchor{disconnected tracing}
d5551862
SS
13793@cindex disconnected tracing
13794You can choose to continue running the trace experiment even if
13795@value{GDBN} disconnects from the target, voluntarily or
13796involuntarily. For commands such as @code{detach}, the debugger will
13797ask what you want to do with the trace. But for unexpected
13798terminations (@value{GDBN} crash, network outage), it would be
13799unfortunate to lose hard-won trace data, so the variable
13800@code{disconnected-tracing} lets you decide whether the trace should
13801continue running without @value{GDBN}.
13802
13803@table @code
13804@item set disconnected-tracing on
13805@itemx set disconnected-tracing off
13806@kindex set disconnected-tracing
13807Choose whether a tracing run should continue to run if @value{GDBN}
13808has disconnected from the target. Note that @code{detach} or
13809@code{quit} will ask you directly what to do about a running trace no
13810matter what this variable's setting, so the variable is mainly useful
13811for handling unexpected situations, such as loss of the network.
13812
13813@item show disconnected-tracing
13814@kindex show disconnected-tracing
13815Show the current choice for disconnected tracing.
13816
13817@end table
13818
13819When you reconnect to the target, the trace experiment may or may not
13820still be running; it might have filled the trace buffer in the
13821meantime, or stopped for one of the other reasons. If it is running,
13822it will continue after reconnection.
13823
13824Upon reconnection, the target will upload information about the
13825tracepoints in effect. @value{GDBN} will then compare that
13826information to the set of tracepoints currently defined, and attempt
13827to match them up, allowing for the possibility that the numbers may
13828have changed due to creation and deletion in the meantime. If one of
13829the target's tracepoints does not match any in @value{GDBN}, the
13830debugger will create a new tracepoint, so that you have a number with
13831which to specify that tracepoint. This matching-up process is
13832necessarily heuristic, and it may result in useless tracepoints being
13833created; you may simply delete them if they are of no use.
b37052ae 13834
4daf5ac0
SS
13835@cindex circular trace buffer
13836If your target agent supports a @dfn{circular trace buffer}, then you
13837can run a trace experiment indefinitely without filling the trace
13838buffer; when space runs out, the agent deletes already-collected trace
13839frames, oldest first, until there is enough room to continue
13840collecting. This is especially useful if your tracepoints are being
13841hit too often, and your trace gets terminated prematurely because the
13842buffer is full. To ask for a circular trace buffer, simply set
81896e36 13843@samp{circular-trace-buffer} to on. You can set this at any time,
4daf5ac0
SS
13844including during tracing; if the agent can do it, it will change
13845buffer handling on the fly, otherwise it will not take effect until
13846the next run.
13847
13848@table @code
13849@item set circular-trace-buffer on
13850@itemx set circular-trace-buffer off
13851@kindex set circular-trace-buffer
13852Choose whether a tracing run should use a linear or circular buffer
13853for trace data. A linear buffer will not lose any trace data, but may
13854fill up prematurely, while a circular buffer will discard old trace
13855data, but it will have always room for the latest tracepoint hits.
13856
13857@item show circular-trace-buffer
13858@kindex show circular-trace-buffer
13859Show the current choice for the trace buffer. Note that this may not
13860match the agent's current buffer handling, nor is it guaranteed to
13861match the setting that might have been in effect during a past run,
13862for instance if you are looking at frames from a trace file.
13863
13864@end table
13865
f6f899bf
HAQ
13866@table @code
13867@item set trace-buffer-size @var{n}
f81d1120 13868@itemx set trace-buffer-size unlimited
f6f899bf
HAQ
13869@kindex set trace-buffer-size
13870Request that the target use a trace buffer of @var{n} bytes. Not all
13871targets will honor the request; they may have a compiled-in size for
13872the trace buffer, or some other limitation. Set to a value of
f81d1120
PA
13873@code{unlimited} or @code{-1} to let the target use whatever size it
13874likes. This is also the default.
f6f899bf
HAQ
13875
13876@item show trace-buffer-size
13877@kindex show trace-buffer-size
13878Show the current requested size for the trace buffer. Note that this
13879will only match the actual size if the target supports size-setting,
13880and was able to handle the requested size. For instance, if the
13881target can only change buffer size between runs, this variable will
13882not reflect the change until the next run starts. Use @code{tstatus}
13883to get a report of the actual buffer size.
13884@end table
13885
f196051f
SS
13886@table @code
13887@item set trace-user @var{text}
13888@kindex set trace-user
13889
13890@item show trace-user
13891@kindex show trace-user
13892
13893@item set trace-notes @var{text}
13894@kindex set trace-notes
13895Set the trace run's notes.
13896
13897@item show trace-notes
13898@kindex show trace-notes
13899Show the trace run's notes.
13900
13901@item set trace-stop-notes @var{text}
13902@kindex set trace-stop-notes
13903Set the trace run's stop notes. The handling of the note is as for
13904@code{tstop} arguments; the set command is convenient way to fix a
13905stop note that is mistaken or incomplete.
13906
13907@item show trace-stop-notes
13908@kindex show trace-stop-notes
13909Show the trace run's stop notes.
13910
13911@end table
13912
c9429232
SS
13913@node Tracepoint Restrictions
13914@subsection Tracepoint Restrictions
13915
13916@cindex tracepoint restrictions
13917There are a number of restrictions on the use of tracepoints. As
13918described above, tracepoint data gathering occurs on the target
13919without interaction from @value{GDBN}. Thus the full capabilities of
13920the debugger are not available during data gathering, and then at data
13921examination time, you will be limited by only having what was
13922collected. The following items describe some common problems, but it
13923is not exhaustive, and you may run into additional difficulties not
13924mentioned here.
13925
13926@itemize @bullet
13927
13928@item
13929Tracepoint expressions are intended to gather objects (lvalues). Thus
13930the full flexibility of GDB's expression evaluator is not available.
13931You cannot call functions, cast objects to aggregate types, access
13932convenience variables or modify values (except by assignment to trace
13933state variables). Some language features may implicitly call
13934functions (for instance Objective-C fields with accessors), and therefore
13935cannot be collected either.
13936
13937@item
13938Collection of local variables, either individually or in bulk with
13939@code{$locals} or @code{$args}, during @code{while-stepping} may
13940behave erratically. The stepping action may enter a new scope (for
13941instance by stepping into a function), or the location of the variable
13942may change (for instance it is loaded into a register). The
13943tracepoint data recorded uses the location information for the
13944variables that is correct for the tracepoint location. When the
13945tracepoint is created, it is not possible, in general, to determine
13946where the steps of a @code{while-stepping} sequence will advance the
13947program---particularly if a conditional branch is stepped.
13948
13949@item
13950Collection of an incompletely-initialized or partially-destroyed object
13951may result in something that @value{GDBN} cannot display, or displays
13952in a misleading way.
13953
13954@item
13955When @value{GDBN} displays a pointer to character it automatically
13956dereferences the pointer to also display characters of the string
13957being pointed to. However, collecting the pointer during tracing does
13958not automatically collect the string. You need to explicitly
13959dereference the pointer and provide size information if you want to
13960collect not only the pointer, but the memory pointed to. For example,
13961@code{*ptr@@50} can be used to collect the 50 element array pointed to
13962by @code{ptr}.
13963
13964@item
13965It is not possible to collect a complete stack backtrace at a
13966tracepoint. Instead, you may collect the registers and a few hundred
d99f7e48 13967bytes from the stack pointer with something like @code{*(unsigned char *)$esp@@300}
c9429232
SS
13968(adjust to use the name of the actual stack pointer register on your
13969target architecture, and the amount of stack you wish to capture).
13970Then the @code{backtrace} command will show a partial backtrace when
13971using a trace frame. The number of stack frames that can be examined
13972depends on the sizes of the frames in the collected stack. Note that
13973if you ask for a block so large that it goes past the bottom of the
13974stack, the target agent may report an error trying to read from an
13975invalid address.
13976
af54718e
SS
13977@item
13978If you do not collect registers at a tracepoint, @value{GDBN} can
13979infer that the value of @code{$pc} must be the same as the address of
13980the tracepoint and use that when you are looking at a trace frame
13981for that tracepoint. However, this cannot work if the tracepoint has
13982multiple locations (for instance if it was set in a function that was
13983inlined), or if it has a @code{while-stepping} loop. In those cases
13984@value{GDBN} will warn you that it can't infer @code{$pc}, and default
13985it to zero.
13986
c9429232
SS
13987@end itemize
13988
b37052ae 13989@node Analyze Collected Data
79a6e687 13990@section Using the Collected Data
b37052ae
EZ
13991
13992After the tracepoint experiment ends, you use @value{GDBN} commands
13993for examining the trace data. The basic idea is that each tracepoint
13994collects a trace @dfn{snapshot} every time it is hit and another
13995snapshot every time it single-steps. All these snapshots are
13996consecutively numbered from zero and go into a buffer, and you can
13997examine them later. The way you examine them is to @dfn{focus} on a
13998specific trace snapshot. When the remote stub is focused on a trace
13999snapshot, it will respond to all @value{GDBN} requests for memory and
14000registers by reading from the buffer which belongs to that snapshot,
14001rather than from @emph{real} memory or registers of the program being
14002debugged. This means that @strong{all} @value{GDBN} commands
14003(@code{print}, @code{info registers}, @code{backtrace}, etc.) will
14004behave as if we were currently debugging the program state as it was
14005when the tracepoint occurred. Any requests for data that are not in
14006the buffer will fail.
14007
14008@menu
14009* tfind:: How to select a trace snapshot
14010* tdump:: How to display all data for a snapshot
6149aea9 14011* save tracepoints:: How to save tracepoints for a future run
b37052ae
EZ
14012@end menu
14013
14014@node tfind
14015@subsection @code{tfind @var{n}}
14016
14017@kindex tfind
14018@cindex select trace snapshot
14019@cindex find trace snapshot
14020The basic command for selecting a trace snapshot from the buffer is
14021@code{tfind @var{n}}, which finds trace snapshot number @var{n},
14022counting from zero. If no argument @var{n} is given, the next
14023snapshot is selected.
14024
14025Here are the various forms of using the @code{tfind} command.
14026
14027@table @code
14028@item tfind start
14029Find the first snapshot in the buffer. This is a synonym for
14030@code{tfind 0} (since 0 is the number of the first snapshot).
14031
14032@item tfind none
14033Stop debugging trace snapshots, resume @emph{live} debugging.
14034
14035@item tfind end
14036Same as @samp{tfind none}.
14037
14038@item tfind
310cdbb6
YQ
14039No argument means find the next trace snapshot or find the first
14040one if no trace snapshot is selected.
b37052ae
EZ
14041
14042@item tfind -
14043Find the previous trace snapshot before the current one. This permits
14044retracing earlier steps.
14045
14046@item tfind tracepoint @var{num}
14047Find the next snapshot associated with tracepoint @var{num}. Search
14048proceeds forward from the last examined trace snapshot. If no
14049argument @var{num} is given, it means find the next snapshot collected
14050for the same tracepoint as the current snapshot.
14051
14052@item tfind pc @var{addr}
14053Find the next snapshot associated with the value @var{addr} of the
14054program counter. Search proceeds forward from the last examined trace
14055snapshot. If no argument @var{addr} is given, it means find the next
14056snapshot with the same value of PC as the current snapshot.
14057
14058@item tfind outside @var{addr1}, @var{addr2}
14059Find the next snapshot whose PC is outside the given range of
081dfbf7 14060addresses (exclusive).
b37052ae
EZ
14061
14062@item tfind range @var{addr1}, @var{addr2}
14063Find the next snapshot whose PC is between @var{addr1} and
081dfbf7 14064@var{addr2} (inclusive).
b37052ae
EZ
14065
14066@item tfind line @r{[}@var{file}:@r{]}@var{n}
14067Find the next snapshot associated with the source line @var{n}. If
14068the optional argument @var{file} is given, refer to line @var{n} in
14069that source file. Search proceeds forward from the last examined
14070trace snapshot. If no argument @var{n} is given, it means find the
14071next line other than the one currently being examined; thus saying
14072@code{tfind line} repeatedly can appear to have the same effect as
14073stepping from line to line in a @emph{live} debugging session.
14074@end table
14075
14076The default arguments for the @code{tfind} commands are specifically
14077designed to make it easy to scan through the trace buffer. For
14078instance, @code{tfind} with no argument selects the next trace
14079snapshot, and @code{tfind -} with no argument selects the previous
14080trace snapshot. So, by giving one @code{tfind} command, and then
14081simply hitting @key{RET} repeatedly you can examine all the trace
14082snapshots in order. Or, by saying @code{tfind -} and then hitting
14083@key{RET} repeatedly you can examine the snapshots in reverse order.
14084The @code{tfind line} command with no argument selects the snapshot
14085for the next source line executed. The @code{tfind pc} command with
14086no argument selects the next snapshot with the same program counter
14087(PC) as the current frame. The @code{tfind tracepoint} command with
14088no argument selects the next trace snapshot collected by the same
14089tracepoint as the current one.
14090
14091In addition to letting you scan through the trace buffer manually,
14092these commands make it easy to construct @value{GDBN} scripts that
14093scan through the trace buffer and print out whatever collected data
14094you are interested in. Thus, if we want to examine the PC, FP, and SP
14095registers from each trace frame in the buffer, we can say this:
14096
14097@smallexample
14098(@value{GDBP}) @b{tfind start}
14099(@value{GDBP}) @b{while ($trace_frame != -1)}
14100> printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \
14101 $trace_frame, $pc, $sp, $fp
14102> tfind
14103> end
14104
14105Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44
14106Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44
14107Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44
14108Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44
14109Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44
14110Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44
14111Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44
14112Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44
14113Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44
14114Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44
14115Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14
14116@end smallexample
14117
14118Or, if we want to examine the variable @code{X} at each source line in
14119the buffer:
14120
14121@smallexample
14122(@value{GDBP}) @b{tfind start}
14123(@value{GDBP}) @b{while ($trace_frame != -1)}
14124> printf "Frame %d, X == %d\n", $trace_frame, X
14125> tfind line
14126> end
14127
14128Frame 0, X = 1
14129Frame 7, X = 2
14130Frame 13, X = 255
14131@end smallexample
14132
14133@node tdump
14134@subsection @code{tdump}
14135@kindex tdump
14136@cindex dump all data collected at tracepoint
14137@cindex tracepoint data, display
14138
14139This command takes no arguments. It prints all the data collected at
14140the current trace snapshot.
14141
14142@smallexample
14143(@value{GDBP}) @b{trace 444}
14144(@value{GDBP}) @b{actions}
14145Enter actions for tracepoint #2, one per line:
14146> collect $regs, $locals, $args, gdb_long_test
14147> end
14148
14149(@value{GDBP}) @b{tstart}
14150
14151(@value{GDBP}) @b{tfind line 444}
14152#0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66)
14153at gdb_test.c:444
14154444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", )
14155
14156(@value{GDBP}) @b{tdump}
14157Data collected at tracepoint 2, trace frame 1:
14158d0 0xc4aa0085 -995491707
14159d1 0x18 24
14160d2 0x80 128
14161d3 0x33 51
14162d4 0x71aea3d 119204413
14163d5 0x22 34
14164d6 0xe0 224
14165d7 0x380035 3670069
14166a0 0x19e24a 1696330
14167a1 0x3000668 50333288
14168a2 0x100 256
14169a3 0x322000 3284992
14170a4 0x3000698 50333336
14171a5 0x1ad3cc 1758156
14172fp 0x30bf3c 0x30bf3c
14173sp 0x30bf34 0x30bf34
14174ps 0x0 0
14175pc 0x20b2c8 0x20b2c8
14176fpcontrol 0x0 0
14177fpstatus 0x0 0
14178fpiaddr 0x0 0
14179p = 0x20e5b4 "gdb-test"
14180p1 = (void *) 0x11
14181p2 = (void *) 0x22
14182p3 = (void *) 0x33
14183p4 = (void *) 0x44
14184p5 = (void *) 0x55
14185p6 = (void *) 0x66
14186gdb_long_test = 17 '\021'
14187
14188(@value{GDBP})
14189@end smallexample
14190
af54718e
SS
14191@code{tdump} works by scanning the tracepoint's current collection
14192actions and printing the value of each expression listed. So
14193@code{tdump} can fail, if after a run, you change the tracepoint's
14194actions to mention variables that were not collected during the run.
14195
14196Also, for tracepoints with @code{while-stepping} loops, @code{tdump}
14197uses the collected value of @code{$pc} to distinguish between trace
14198frames that were collected at the tracepoint hit, and frames that were
14199collected while stepping. This allows it to correctly choose whether
14200to display the basic list of collections, or the collections from the
14201body of the while-stepping loop. However, if @code{$pc} was not collected,
14202then @code{tdump} will always attempt to dump using the basic collection
14203list, and may fail if a while-stepping frame does not include all the
14204same data that is collected at the tracepoint hit.
14205@c This is getting pretty arcane, example would be good.
14206
6149aea9
PA
14207@node save tracepoints
14208@subsection @code{save tracepoints @var{filename}}
14209@kindex save tracepoints
b37052ae
EZ
14210@kindex save-tracepoints
14211@cindex save tracepoints for future sessions
14212
14213This command saves all current tracepoint definitions together with
14214their actions and passcounts, into a file @file{@var{filename}}
14215suitable for use in a later debugging session. To read the saved
14216tracepoint definitions, use the @code{source} command (@pxref{Command
6149aea9
PA
14217Files}). The @w{@code{save-tracepoints}} command is a deprecated
14218alias for @w{@code{save tracepoints}}
b37052ae
EZ
14219
14220@node Tracepoint Variables
14221@section Convenience Variables for Tracepoints
14222@cindex tracepoint variables
14223@cindex convenience variables for tracepoints
14224
14225@table @code
14226@vindex $trace_frame
14227@item (int) $trace_frame
14228The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no
14229snapshot is selected.
14230
14231@vindex $tracepoint
14232@item (int) $tracepoint
14233The tracepoint for the current trace snapshot.
14234
14235@vindex $trace_line
14236@item (int) $trace_line
14237The line number for the current trace snapshot.
14238
14239@vindex $trace_file
14240@item (char []) $trace_file
14241The source file for the current trace snapshot.
14242
14243@vindex $trace_func
14244@item (char []) $trace_func
14245The name of the function containing @code{$tracepoint}.
14246@end table
14247
14248Note: @code{$trace_file} is not suitable for use in @code{printf},
14249use @code{output} instead.
14250
14251Here's a simple example of using these convenience variables for
14252stepping through all the trace snapshots and printing some of their
f61e138d
SS
14253data. Note that these are not the same as trace state variables,
14254which are managed by the target.
b37052ae
EZ
14255
14256@smallexample
14257(@value{GDBP}) @b{tfind start}
14258
14259(@value{GDBP}) @b{while $trace_frame != -1}
14260> output $trace_file
14261> printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint
14262> tfind
14263> end
14264@end smallexample
14265
00bf0b85
SS
14266@node Trace Files
14267@section Using Trace Files
14268@cindex trace files
14269
14270In some situations, the target running a trace experiment may no
14271longer be available; perhaps it crashed, or the hardware was needed
14272for a different activity. To handle these cases, you can arrange to
14273dump the trace data into a file, and later use that file as a source
14274of trace data, via the @code{target tfile} command.
14275
14276@table @code
14277
14278@kindex tsave
14279@item tsave [ -r ] @var{filename}
d0353e76 14280@itemx tsave [-ctf] @var{dirname}
00bf0b85
SS
14281Save the trace data to @var{filename}. By default, this command
14282assumes that @var{filename} refers to the host filesystem, so if
14283necessary @value{GDBN} will copy raw trace data up from the target and
14284then save it. If the target supports it, you can also supply the
14285optional argument @code{-r} (``remote'') to direct the target to save
14286the data directly into @var{filename} in its own filesystem, which may be
14287more efficient if the trace buffer is very large. (Note, however, that
14288@code{target tfile} can only read from files accessible to the host.)
d0353e76 14289By default, this command will save trace frame in tfile format.
be06ba8c 14290You can supply the optional argument @code{-ctf} to save data in CTF
d0353e76
YQ
14291format. The @dfn{Common Trace Format} (CTF) is proposed as a trace format
14292that can be shared by multiple debugging and tracing tools. Please go to
14293@indicateurl{http://www.efficios.com/ctf} to get more information.
00bf0b85
SS
14294
14295@kindex target tfile
14296@kindex tfile
393fd4c3
YQ
14297@kindex target ctf
14298@kindex ctf
00bf0b85 14299@item target tfile @var{filename}
393fd4c3
YQ
14300@itemx target ctf @var{dirname}
14301Use the file named @var{filename} or directory named @var{dirname} as
14302a source of trace data. Commands that examine data work as they do with
14303a live target, but it is not possible to run any new trace experiments.
14304@code{tstatus} will report the state of the trace run at the moment
14305the data was saved, as well as the current trace frame you are examining.
697aa1b7 14306Both @var{filename} and @var{dirname} must be on a filesystem accessible to
393fd4c3
YQ
14307the host.
14308
14309@smallexample
14310(@value{GDBP}) target ctf ctf.ctf
14311(@value{GDBP}) tfind
14312Found trace frame 0, tracepoint 2
1431339 ++a; /* set tracepoint 1 here */
14314(@value{GDBP}) tdump
14315Data collected at tracepoint 2, trace frame 0:
14316i = 0
14317a = 0
14318b = 1 '\001'
14319c = @{"123", "456", "789", "123", "456", "789"@}
14320d = @{@{@{a = 1, b = 2@}, @{a = 3, b = 4@}@}, @{@{a = 5, b = 6@}, @{a = 7, b = 8@}@}@}
14321(@value{GDBP}) p b
14322$1 = 1
14323@end smallexample
00bf0b85
SS
14324
14325@end table
14326
df0cd8c5
JB
14327@node Overlays
14328@chapter Debugging Programs That Use Overlays
14329@cindex overlays
14330
14331If your program is too large to fit completely in your target system's
14332memory, you can sometimes use @dfn{overlays} to work around this
14333problem. @value{GDBN} provides some support for debugging programs that
14334use overlays.
14335
14336@menu
14337* How Overlays Work:: A general explanation of overlays.
14338* Overlay Commands:: Managing overlays in @value{GDBN}.
14339* Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are
14340 mapped by asking the inferior.
14341* Overlay Sample Program:: A sample program using overlays.
14342@end menu
14343
14344@node How Overlays Work
14345@section How Overlays Work
14346@cindex mapped overlays
14347@cindex unmapped overlays
14348@cindex load address, overlay's
14349@cindex mapped address
14350@cindex overlay area
14351
14352Suppose you have a computer whose instruction address space is only 64
14353kilobytes long, but which has much more memory which can be accessed by
14354other means: special instructions, segment registers, or memory
14355management hardware, for example. Suppose further that you want to
14356adapt a program which is larger than 64 kilobytes to run on this system.
14357
14358One solution is to identify modules of your program which are relatively
14359independent, and need not call each other directly; call these modules
14360@dfn{overlays}. Separate the overlays from the main program, and place
14361their machine code in the larger memory. Place your main program in
14362instruction memory, but leave at least enough space there to hold the
14363largest overlay as well.
14364
14365Now, to call a function located in an overlay, you must first copy that
14366overlay's machine code from the large memory into the space set aside
14367for it in the instruction memory, and then jump to its entry point
14368there.
14369
c928edc0
AC
14370@c NB: In the below the mapped area's size is greater or equal to the
14371@c size of all overlays. This is intentional to remind the developer
14372@c that overlays don't necessarily need to be the same size.
14373
474c8240 14374@smallexample
df0cd8c5 14375@group
c928edc0
AC
14376 Data Instruction Larger
14377Address Space Address Space Address Space
14378+-----------+ +-----------+ +-----------+
14379| | | | | |
14380+-----------+ +-----------+ +-----------+<-- overlay 1
14381| program | | main | .----| overlay 1 | load address
14382| variables | | program | | +-----------+
14383| and heap | | | | | |
14384+-----------+ | | | +-----------+<-- overlay 2
14385| | +-----------+ | | | load address
14386+-----------+ | | | .-| overlay 2 |
14387 | | | | | |
14388 mapped --->+-----------+ | | +-----------+
14389 address | | | | | |
14390 | overlay | <-' | | |
14391 | area | <---' +-----------+<-- overlay 3
14392 | | <---. | | load address
14393 +-----------+ `--| overlay 3 |
14394 | | | |
14395 +-----------+ | |
14396 +-----------+
14397 | |
14398 +-----------+
14399
14400 @anchor{A code overlay}A code overlay
df0cd8c5 14401@end group
474c8240 14402@end smallexample
df0cd8c5 14403
c928edc0
AC
14404The diagram (@pxref{A code overlay}) shows a system with separate data
14405and instruction address spaces. To map an overlay, the program copies
14406its code from the larger address space to the instruction address space.
14407Since the overlays shown here all use the same mapped address, only one
14408may be mapped at a time. For a system with a single address space for
14409data and instructions, the diagram would be similar, except that the
14410program variables and heap would share an address space with the main
14411program and the overlay area.
df0cd8c5
JB
14412
14413An overlay loaded into instruction memory and ready for use is called a
14414@dfn{mapped} overlay; its @dfn{mapped address} is its address in the
14415instruction memory. An overlay not present (or only partially present)
14416in instruction memory is called @dfn{unmapped}; its @dfn{load address}
14417is its address in the larger memory. The mapped address is also called
14418the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also
14419called the @dfn{load memory address}, or @dfn{LMA}.
14420
14421Unfortunately, overlays are not a completely transparent way to adapt a
14422program to limited instruction memory. They introduce a new set of
14423global constraints you must keep in mind as you design your program:
14424
14425@itemize @bullet
14426
14427@item
14428Before calling or returning to a function in an overlay, your program
14429must make sure that overlay is actually mapped. Otherwise, the call or
14430return will transfer control to the right address, but in the wrong
14431overlay, and your program will probably crash.
14432
14433@item
14434If the process of mapping an overlay is expensive on your system, you
14435will need to choose your overlays carefully to minimize their effect on
14436your program's performance.
14437
14438@item
14439The executable file you load onto your system must contain each
14440overlay's instructions, appearing at the overlay's load address, not its
14441mapped address. However, each overlay's instructions must be relocated
14442and its symbols defined as if the overlay were at its mapped address.
14443You can use GNU linker scripts to specify different load and relocation
14444addresses for pieces of your program; see @ref{Overlay Description,,,
14445ld.info, Using ld: the GNU linker}.
14446
14447@item
14448The procedure for loading executable files onto your system must be able
14449to load their contents into the larger address space as well as the
14450instruction and data spaces.
14451
14452@end itemize
14453
14454The overlay system described above is rather simple, and could be
14455improved in many ways:
14456
14457@itemize @bullet
14458
14459@item
14460If your system has suitable bank switch registers or memory management
14461hardware, you could use those facilities to make an overlay's load area
14462contents simply appear at their mapped address in instruction space.
14463This would probably be faster than copying the overlay to its mapped
14464area in the usual way.
14465
14466@item
14467If your overlays are small enough, you could set aside more than one
14468overlay area, and have more than one overlay mapped at a time.
14469
14470@item
14471You can use overlays to manage data, as well as instructions. In
14472general, data overlays are even less transparent to your design than
14473code overlays: whereas code overlays only require care when you call or
14474return to functions, data overlays require care every time you access
14475the data. Also, if you change the contents of a data overlay, you
14476must copy its contents back out to its load address before you can copy a
14477different data overlay into the same mapped area.
14478
14479@end itemize
14480
14481
14482@node Overlay Commands
14483@section Overlay Commands
14484
14485To use @value{GDBN}'s overlay support, each overlay in your program must
14486correspond to a separate section of the executable file. The section's
14487virtual memory address and load memory address must be the overlay's
14488mapped and load addresses. Identifying overlays with sections allows
14489@value{GDBN} to determine the appropriate address of a function or
14490variable, depending on whether the overlay is mapped or not.
14491
14492@value{GDBN}'s overlay commands all start with the word @code{overlay};
14493you can abbreviate this as @code{ov} or @code{ovly}. The commands are:
14494
14495@table @code
14496@item overlay off
4644b6e3 14497@kindex overlay
df0cd8c5
JB
14498Disable @value{GDBN}'s overlay support. When overlay support is
14499disabled, @value{GDBN} assumes that all functions and variables are
14500always present at their mapped addresses. By default, @value{GDBN}'s
14501overlay support is disabled.
14502
14503@item overlay manual
df0cd8c5
JB
14504@cindex manual overlay debugging
14505Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN}
14506relies on you to tell it which overlays are mapped, and which are not,
14507using the @code{overlay map-overlay} and @code{overlay unmap-overlay}
14508commands described below.
14509
14510@item overlay map-overlay @var{overlay}
14511@itemx overlay map @var{overlay}
df0cd8c5
JB
14512@cindex map an overlay
14513Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must
14514be the name of the object file section containing the overlay. When an
14515overlay is mapped, @value{GDBN} assumes it can find the overlay's
14516functions and variables at their mapped addresses. @value{GDBN} assumes
14517that any other overlays whose mapped ranges overlap that of
14518@var{overlay} are now unmapped.
14519
14520@item overlay unmap-overlay @var{overlay}
14521@itemx overlay unmap @var{overlay}
df0cd8c5
JB
14522@cindex unmap an overlay
14523Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay}
14524must be the name of the object file section containing the overlay.
14525When an overlay is unmapped, @value{GDBN} assumes it can find the
14526overlay's functions and variables at their load addresses.
14527
14528@item overlay auto
df0cd8c5
JB
14529Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN}
14530consults a data structure the overlay manager maintains in the inferior
14531to see which overlays are mapped. For details, see @ref{Automatic
14532Overlay Debugging}.
14533
14534@item overlay load-target
14535@itemx overlay load
df0cd8c5
JB
14536@cindex reloading the overlay table
14537Re-read the overlay table from the inferior. Normally, @value{GDBN}
14538re-reads the table @value{GDBN} automatically each time the inferior
14539stops, so this command should only be necessary if you have changed the
14540overlay mapping yourself using @value{GDBN}. This command is only
14541useful when using automatic overlay debugging.
14542
14543@item overlay list-overlays
14544@itemx overlay list
14545@cindex listing mapped overlays
14546Display a list of the overlays currently mapped, along with their mapped
14547addresses, load addresses, and sizes.
14548
14549@end table
14550
14551Normally, when @value{GDBN} prints a code address, it includes the name
14552of the function the address falls in:
14553
474c8240 14554@smallexample
f7dc1244 14555(@value{GDBP}) print main
df0cd8c5 14556$3 = @{int ()@} 0x11a0 <main>
474c8240 14557@end smallexample
df0cd8c5
JB
14558@noindent
14559When overlay debugging is enabled, @value{GDBN} recognizes code in
14560unmapped overlays, and prints the names of unmapped functions with
14561asterisks around them. For example, if @code{foo} is a function in an
14562unmapped overlay, @value{GDBN} prints it this way:
14563
474c8240 14564@smallexample
f7dc1244 14565(@value{GDBP}) overlay list
df0cd8c5 14566No sections are mapped.
f7dc1244 14567(@value{GDBP}) print foo
df0cd8c5 14568$5 = @{int (int)@} 0x100000 <*foo*>
474c8240 14569@end smallexample
df0cd8c5
JB
14570@noindent
14571When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's
14572name normally:
14573
474c8240 14574@smallexample
f7dc1244 14575(@value{GDBP}) overlay list
b383017d 14576Section .ov.foo.text, loaded at 0x100000 - 0x100034,
df0cd8c5 14577 mapped at 0x1016 - 0x104a
f7dc1244 14578(@value{GDBP}) print foo
df0cd8c5 14579$6 = @{int (int)@} 0x1016 <foo>
474c8240 14580@end smallexample
df0cd8c5
JB
14581
14582When overlay debugging is enabled, @value{GDBN} can find the correct
14583address for functions and variables in an overlay, whether or not the
14584overlay is mapped. This allows most @value{GDBN} commands, like
14585@code{break} and @code{disassemble}, to work normally, even on unmapped
14586code. However, @value{GDBN}'s breakpoint support has some limitations:
14587
14588@itemize @bullet
14589@item
14590@cindex breakpoints in overlays
14591@cindex overlays, setting breakpoints in
14592You can set breakpoints in functions in unmapped overlays, as long as
14593@value{GDBN} can write to the overlay at its load address.
14594@item
14595@value{GDBN} can not set hardware or simulator-based breakpoints in
14596unmapped overlays. However, if you set a breakpoint at the end of your
14597overlay manager (and tell @value{GDBN} which overlays are now mapped, if
14598you are using manual overlay management), @value{GDBN} will re-set its
14599breakpoints properly.
14600@end itemize
14601
14602
14603@node Automatic Overlay Debugging
14604@section Automatic Overlay Debugging
14605@cindex automatic overlay debugging
14606
14607@value{GDBN} can automatically track which overlays are mapped and which
14608are not, given some simple co-operation from the overlay manager in the
14609inferior. If you enable automatic overlay debugging with the
14610@code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN}
14611looks in the inferior's memory for certain variables describing the
14612current state of the overlays.
14613
14614Here are the variables your overlay manager must define to support
14615@value{GDBN}'s automatic overlay debugging:
14616
14617@table @asis
14618
14619@item @code{_ovly_table}:
14620This variable must be an array of the following structures:
14621
474c8240 14622@smallexample
df0cd8c5
JB
14623struct
14624@{
14625 /* The overlay's mapped address. */
14626 unsigned long vma;
14627
14628 /* The size of the overlay, in bytes. */
14629 unsigned long size;
14630
14631 /* The overlay's load address. */
14632 unsigned long lma;
14633
14634 /* Non-zero if the overlay is currently mapped;
14635 zero otherwise. */
14636 unsigned long mapped;
14637@}
474c8240 14638@end smallexample
df0cd8c5
JB
14639
14640@item @code{_novlys}:
14641This variable must be a four-byte signed integer, holding the total
14642number of elements in @code{_ovly_table}.
14643
14644@end table
14645
14646To decide whether a particular overlay is mapped or not, @value{GDBN}
14647looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and
14648@code{lma} members equal the VMA and LMA of the overlay's section in the
14649executable file. When @value{GDBN} finds a matching entry, it consults
14650the entry's @code{mapped} member to determine whether the overlay is
14651currently mapped.
14652
81d46470 14653In addition, your overlay manager may define a function called
def71bfa 14654@code{_ovly_debug_event}. If this function is defined, @value{GDBN}
81d46470
MS
14655will silently set a breakpoint there. If the overlay manager then
14656calls this function whenever it has changed the overlay table, this
14657will enable @value{GDBN} to accurately keep track of which overlays
14658are in program memory, and update any breakpoints that may be set
b383017d 14659in overlays. This will allow breakpoints to work even if the
81d46470
MS
14660overlays are kept in ROM or other non-writable memory while they
14661are not being executed.
df0cd8c5
JB
14662
14663@node Overlay Sample Program
14664@section Overlay Sample Program
14665@cindex overlay example program
14666
14667When linking a program which uses overlays, you must place the overlays
14668at their load addresses, while relocating them to run at their mapped
14669addresses. To do this, you must write a linker script (@pxref{Overlay
14670Description,,, ld.info, Using ld: the GNU linker}). Unfortunately,
14671since linker scripts are specific to a particular host system, target
14672architecture, and target memory layout, this manual cannot provide
14673portable sample code demonstrating @value{GDBN}'s overlay support.
14674
14675However, the @value{GDBN} source distribution does contain an overlaid
14676program, with linker scripts for a few systems, as part of its test
14677suite. The program consists of the following files from
14678@file{gdb/testsuite/gdb.base}:
14679
14680@table @file
14681@item overlays.c
14682The main program file.
14683@item ovlymgr.c
14684A simple overlay manager, used by @file{overlays.c}.
14685@item foo.c
14686@itemx bar.c
14687@itemx baz.c
14688@itemx grbx.c
14689Overlay modules, loaded and used by @file{overlays.c}.
14690@item d10v.ld
14691@itemx m32r.ld
14692Linker scripts for linking the test program on the @code{d10v-elf}
14693and @code{m32r-elf} targets.
14694@end table
14695
14696You can build the test program using the @code{d10v-elf} GCC
14697cross-compiler like this:
14698
474c8240 14699@smallexample
df0cd8c5
JB
14700$ d10v-elf-gcc -g -c overlays.c
14701$ d10v-elf-gcc -g -c ovlymgr.c
14702$ d10v-elf-gcc -g -c foo.c
14703$ d10v-elf-gcc -g -c bar.c
14704$ d10v-elf-gcc -g -c baz.c
14705$ d10v-elf-gcc -g -c grbx.c
14706$ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
14707 baz.o grbx.o -Wl,-Td10v.ld -o overlays
474c8240 14708@end smallexample
df0cd8c5
JB
14709
14710The build process is identical for any other architecture, except that
14711you must substitute the appropriate compiler and linker script for the
14712target system for @code{d10v-elf-gcc} and @code{d10v.ld}.
14713
14714
6d2ebf8b 14715@node Languages
c906108c
SS
14716@chapter Using @value{GDBN} with Different Languages
14717@cindex languages
14718
c906108c
SS
14719Although programming languages generally have common aspects, they are
14720rarely expressed in the same manner. For instance, in ANSI C,
14721dereferencing a pointer @code{p} is accomplished by @code{*p}, but in
14722Modula-2, it is accomplished by @code{p^}. Values can also be
5d161b24 14723represented (and displayed) differently. Hex numbers in C appear as
c906108c 14724@samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}.
c906108c
SS
14725
14726@cindex working language
14727Language-specific information is built into @value{GDBN} for some languages,
14728allowing you to express operations like the above in your program's
14729native language, and allowing @value{GDBN} to output values in a manner
14730consistent with the syntax of your program's native language. The
14731language you use to build expressions is called the @dfn{working
14732language}.
14733
14734@menu
14735* Setting:: Switching between source languages
14736* Show:: Displaying the language
c906108c 14737* Checks:: Type and range checks
79a6e687
BW
14738* Supported Languages:: Supported languages
14739* Unsupported Languages:: Unsupported languages
c906108c
SS
14740@end menu
14741
6d2ebf8b 14742@node Setting
79a6e687 14743@section Switching Between Source Languages
c906108c
SS
14744
14745There are two ways to control the working language---either have @value{GDBN}
14746set it automatically, or select it manually yourself. You can use the
14747@code{set language} command for either purpose. On startup, @value{GDBN}
14748defaults to setting the language automatically. The working language is
14749used to determine how expressions you type are interpreted, how values
14750are printed, etc.
14751
14752In addition to the working language, every source file that
14753@value{GDBN} knows about has its own working language. For some object
14754file formats, the compiler might indicate which language a particular
14755source file is in. However, most of the time @value{GDBN} infers the
14756language from the name of the file. The language of a source file
b37052ae 14757controls whether C@t{++} names are demangled---this way @code{backtrace} can
c906108c 14758show each frame appropriately for its own language. There is no way to
d4f3574e
SS
14759set the language of a source file from within @value{GDBN}, but you can
14760set the language associated with a filename extension. @xref{Show, ,
79a6e687 14761Displaying the Language}.
c906108c
SS
14762
14763This is most commonly a problem when you use a program, such
5d161b24 14764as @code{cfront} or @code{f2c}, that generates C but is written in
c906108c
SS
14765another language. In that case, make the
14766program use @code{#line} directives in its C output; that way
14767@value{GDBN} will know the correct language of the source code of the original
14768program, and will display that source code, not the generated C code.
14769
14770@menu
14771* Filenames:: Filename extensions and languages.
14772* Manually:: Setting the working language manually
14773* Automatically:: Having @value{GDBN} infer the source language
14774@end menu
14775
6d2ebf8b 14776@node Filenames
79a6e687 14777@subsection List of Filename Extensions and Languages
c906108c
SS
14778
14779If a source file name ends in one of the following extensions, then
14780@value{GDBN} infers that its language is the one indicated.
14781
14782@table @file
e07c999f
PH
14783@item .ada
14784@itemx .ads
14785@itemx .adb
14786@itemx .a
14787Ada source file.
c906108c
SS
14788
14789@item .c
14790C source file
14791
14792@item .C
14793@itemx .cc
14794@itemx .cp
14795@itemx .cpp
14796@itemx .cxx
14797@itemx .c++
b37052ae 14798C@t{++} source file
c906108c 14799
6aecb9c2
JB
14800@item .d
14801D source file
14802
b37303ee
AF
14803@item .m
14804Objective-C source file
14805
c906108c
SS
14806@item .f
14807@itemx .F
14808Fortran source file
14809
c906108c
SS
14810@item .mod
14811Modula-2 source file
c906108c
SS
14812
14813@item .s
14814@itemx .S
14815Assembler source file. This actually behaves almost like C, but
14816@value{GDBN} does not skip over function prologues when stepping.
14817@end table
14818
14819In addition, you may set the language associated with a filename
79a6e687 14820extension. @xref{Show, , Displaying the Language}.
c906108c 14821
6d2ebf8b 14822@node Manually
79a6e687 14823@subsection Setting the Working Language
c906108c
SS
14824
14825If you allow @value{GDBN} to set the language automatically,
14826expressions are interpreted the same way in your debugging session and
14827your program.
14828
14829@kindex set language
14830If you wish, you may set the language manually. To do this, issue the
14831command @samp{set language @var{lang}}, where @var{lang} is the name of
5d161b24 14832a language, such as
c906108c 14833@code{c} or @code{modula-2}.
c906108c
SS
14834For a list of the supported languages, type @samp{set language}.
14835
c906108c
SS
14836Setting the language manually prevents @value{GDBN} from updating the working
14837language automatically. This can lead to confusion if you try
14838to debug a program when the working language is not the same as the
14839source language, when an expression is acceptable to both
14840languages---but means different things. For instance, if the current
14841source file were written in C, and @value{GDBN} was parsing Modula-2, a
14842command such as:
14843
474c8240 14844@smallexample
c906108c 14845print a = b + c
474c8240 14846@end smallexample
c906108c
SS
14847
14848@noindent
14849might not have the effect you intended. In C, this means to add
14850@code{b} and @code{c} and place the result in @code{a}. The result
14851printed would be the value of @code{a}. In Modula-2, this means to compare
14852@code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value.
c906108c 14853
6d2ebf8b 14854@node Automatically
79a6e687 14855@subsection Having @value{GDBN} Infer the Source Language
c906108c
SS
14856
14857To have @value{GDBN} set the working language automatically, use
14858@samp{set language local} or @samp{set language auto}. @value{GDBN}
14859then infers the working language. That is, when your program stops in a
14860frame (usually by encountering a breakpoint), @value{GDBN} sets the
14861working language to the language recorded for the function in that
14862frame. If the language for a frame is unknown (that is, if the function
14863or block corresponding to the frame was defined in a source file that
14864does not have a recognized extension), the current working language is
14865not changed, and @value{GDBN} issues a warning.
14866
14867This may not seem necessary for most programs, which are written
14868entirely in one source language. However, program modules and libraries
14869written in one source language can be used by a main program written in
14870a different source language. Using @samp{set language auto} in this
14871case frees you from having to set the working language manually.
14872
6d2ebf8b 14873@node Show
79a6e687 14874@section Displaying the Language
c906108c
SS
14875
14876The following commands help you find out which language is the
14877working language, and also what language source files were written in.
14878
c906108c
SS
14879@table @code
14880@item show language
403cb6b1 14881@anchor{show language}
9c16f35a 14882@kindex show language
c906108c
SS
14883Display the current working language. This is the
14884language you can use with commands such as @code{print} to
14885build and compute expressions that may involve variables in your program.
14886
14887@item info frame
4644b6e3 14888@kindex info frame@r{, show the source language}
5d161b24 14889Display the source language for this frame. This language becomes the
c906108c 14890working language if you use an identifier from this frame.
79a6e687 14891@xref{Frame Info, ,Information about a Frame}, to identify the other
c906108c
SS
14892information listed here.
14893
14894@item info source
4644b6e3 14895@kindex info source@r{, show the source language}
c906108c 14896Display the source language of this source file.
5d161b24 14897@xref{Symbols, ,Examining the Symbol Table}, to identify the other
c906108c
SS
14898information listed here.
14899@end table
14900
14901In unusual circumstances, you may have source files with extensions
14902not in the standard list. You can then set the extension associated
14903with a language explicitly:
14904
c906108c 14905@table @code
09d4efe1 14906@item set extension-language @var{ext} @var{language}
9c16f35a 14907@kindex set extension-language
09d4efe1
EZ
14908Tell @value{GDBN} that source files with extension @var{ext} are to be
14909assumed as written in the source language @var{language}.
c906108c
SS
14910
14911@item info extensions
9c16f35a 14912@kindex info extensions
c906108c
SS
14913List all the filename extensions and the associated languages.
14914@end table
14915
6d2ebf8b 14916@node Checks
79a6e687 14917@section Type and Range Checking
c906108c 14918
c906108c
SS
14919Some languages are designed to guard you against making seemingly common
14920errors through a series of compile- and run-time checks. These include
a451cb65 14921checking the type of arguments to functions and operators and making
c906108c
SS
14922sure mathematical overflows are caught at run time. Checks such as
14923these help to ensure a program's correctness once it has been compiled
a451cb65 14924by eliminating type mismatches and providing active checks for range
c906108c
SS
14925errors when your program is running.
14926
a451cb65
KS
14927By default @value{GDBN} checks for these errors according to the
14928rules of the current source language. Although @value{GDBN} does not check
14929the statements in your program, it can check expressions entered directly
14930into @value{GDBN} for evaluation via the @code{print} command, for example.
c906108c
SS
14931
14932@menu
14933* Type Checking:: An overview of type checking
14934* Range Checking:: An overview of range checking
14935@end menu
14936
14937@cindex type checking
14938@cindex checks, type
6d2ebf8b 14939@node Type Checking
79a6e687 14940@subsection An Overview of Type Checking
c906108c 14941
a451cb65 14942Some languages, such as C and C@t{++}, are strongly typed, meaning that the
c906108c
SS
14943arguments to operators and functions have to be of the correct type,
14944otherwise an error occurs. These checks prevent type mismatch
14945errors from ever causing any run-time problems. For example,
14946
14947@smallexample
a451cb65
KS
14948int klass::my_method(char *b) @{ return b ? 1 : 2; @}
14949
14950(@value{GDBP}) print obj.my_method (0)
14951$1 = 2
c906108c 14952@exdent but
a451cb65
KS
14953(@value{GDBP}) print obj.my_method (0x1234)
14954Cannot resolve method klass::my_method to any overloaded instance
c906108c
SS
14955@end smallexample
14956
a451cb65
KS
14957The second example fails because in C@t{++} the integer constant
14958@samp{0x1234} is not type-compatible with the pointer parameter type.
c906108c 14959
a451cb65
KS
14960For the expressions you use in @value{GDBN} commands, you can tell
14961@value{GDBN} to not enforce strict type checking or
5d161b24 14962to treat any mismatches as errors and abandon the expression;
a451cb65
KS
14963When type checking is disabled, @value{GDBN} successfully evaluates
14964expressions like the second example above.
c906108c 14965
a451cb65 14966Even if type checking is off, there may be other reasons
5d161b24
DB
14967related to type that prevent @value{GDBN} from evaluating an expression.
14968For instance, @value{GDBN} does not know how to add an @code{int} and
14969a @code{struct foo}. These particular type errors have nothing to do
a451cb65
KS
14970with the language in use and usually arise from expressions which make
14971little sense to evaluate anyway.
c906108c 14972
a451cb65 14973@value{GDBN} provides some additional commands for controlling type checking:
c906108c 14974
c906108c
SS
14975@kindex set check type
14976@kindex show check type
14977@table @code
c906108c
SS
14978@item set check type on
14979@itemx set check type off
a451cb65 14980Set strict type checking on or off. If any type mismatches occur in
d4f3574e 14981evaluating an expression while type checking is on, @value{GDBN} prints a
c906108c
SS
14982message and aborts evaluation of the expression.
14983
a451cb65
KS
14984@item show check type
14985Show the current setting of type checking and whether @value{GDBN}
14986is enforcing strict type checking rules.
c906108c
SS
14987@end table
14988
14989@cindex range checking
14990@cindex checks, range
6d2ebf8b 14991@node Range Checking
79a6e687 14992@subsection An Overview of Range Checking
c906108c
SS
14993
14994In some languages (such as Modula-2), it is an error to exceed the
14995bounds of a type; this is enforced with run-time checks. Such range
14996checking is meant to ensure program correctness by making sure
14997computations do not overflow, or indices on an array element access do
14998not exceed the bounds of the array.
14999
15000For expressions you use in @value{GDBN} commands, you can tell
15001@value{GDBN} to treat range errors in one of three ways: ignore them,
15002always treat them as errors and abandon the expression, or issue
15003warnings but evaluate the expression anyway.
15004
15005A range error can result from numerical overflow, from exceeding an
15006array index bound, or when you type a constant that is not a member
15007of any type. Some languages, however, do not treat overflows as an
15008error. In many implementations of C, mathematical overflow causes the
15009result to ``wrap around'' to lower values---for example, if @var{m} is
15010the largest integer value, and @var{s} is the smallest, then
15011
474c8240 15012@smallexample
c906108c 15013@var{m} + 1 @result{} @var{s}
474c8240 15014@end smallexample
c906108c
SS
15015
15016This, too, is specific to individual languages, and in some cases
79a6e687
BW
15017specific to individual compilers or machines. @xref{Supported Languages, ,
15018Supported Languages}, for further details on specific languages.
c906108c
SS
15019
15020@value{GDBN} provides some additional commands for controlling the range checker:
15021
c906108c
SS
15022@kindex set check range
15023@kindex show check range
15024@table @code
15025@item set check range auto
15026Set range checking on or off based on the current working language.
79a6e687 15027@xref{Supported Languages, ,Supported Languages}, for the default settings for
c906108c
SS
15028each language.
15029
15030@item set check range on
15031@itemx set check range off
15032Set range checking on or off, overriding the default setting for the
15033current working language. A warning is issued if the setting does not
c3f6f71d
JM
15034match the language default. If a range error occurs and range checking is on,
15035then a message is printed and evaluation of the expression is aborted.
c906108c
SS
15036
15037@item set check range warn
15038Output messages when the @value{GDBN} range checker detects a range error,
15039but attempt to evaluate the expression anyway. Evaluating the
15040expression may still be impossible for other reasons, such as accessing
15041memory that the process does not own (a typical example from many Unix
15042systems).
15043
15044@item show range
15045Show the current setting of the range checker, and whether or not it is
15046being set automatically by @value{GDBN}.
15047@end table
c906108c 15048
79a6e687
BW
15049@node Supported Languages
15050@section Supported Languages
c906108c 15051
9c37b5ae 15052@value{GDBN} supports C, C@t{++}, D, Go, Objective-C, Fortran,
0bdfa368 15053OpenCL C, Pascal, Rust, assembly, Modula-2, and Ada.
cce74817 15054@c This is false ...
c906108c
SS
15055Some @value{GDBN} features may be used in expressions regardless of the
15056language you use: the @value{GDBN} @code{@@} and @code{::} operators,
15057and the @samp{@{type@}addr} construct (@pxref{Expressions,
15058,Expressions}) can be used with the constructs of any supported
15059language.
15060
15061The following sections detail to what degree each source language is
15062supported by @value{GDBN}. These sections are not meant to be language
15063tutorials or references, but serve only as a reference guide to what the
15064@value{GDBN} expression parser accepts, and what input and output
15065formats should look like for different languages. There are many good
15066books written on each of these languages; please look to these for a
15067language reference or tutorial.
15068
c906108c 15069@menu
b37303ee 15070* C:: C and C@t{++}
6aecb9c2 15071* D:: D
a766d390 15072* Go:: Go
b383017d 15073* Objective-C:: Objective-C
f4b8a18d 15074* OpenCL C:: OpenCL C
09d4efe1 15075* Fortran:: Fortran
9c16f35a 15076* Pascal:: Pascal
0bdfa368 15077* Rust:: Rust
b37303ee 15078* Modula-2:: Modula-2
e07c999f 15079* Ada:: Ada
c906108c
SS
15080@end menu
15081
6d2ebf8b 15082@node C
b37052ae 15083@subsection C and C@t{++}
7a292a7a 15084
b37052ae
EZ
15085@cindex C and C@t{++}
15086@cindex expressions in C or C@t{++}
c906108c 15087
b37052ae 15088Since C and C@t{++} are so closely related, many features of @value{GDBN} apply
c906108c
SS
15089to both languages. Whenever this is the case, we discuss those languages
15090together.
15091
41afff9a
EZ
15092@cindex C@t{++}
15093@cindex @code{g++}, @sc{gnu} C@t{++} compiler
b37052ae
EZ
15094@cindex @sc{gnu} C@t{++}
15095The C@t{++} debugging facilities are jointly implemented by the C@t{++}
15096compiler and @value{GDBN}. Therefore, to debug your C@t{++} code
15097effectively, you must compile your C@t{++} programs with a supported
15098C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++}
c906108c
SS
15099compiler (@code{aCC}).
15100
c906108c 15101@menu
b37052ae
EZ
15102* C Operators:: C and C@t{++} operators
15103* C Constants:: C and C@t{++} constants
79a6e687 15104* C Plus Plus Expressions:: C@t{++} expressions
b37052ae
EZ
15105* C Defaults:: Default settings for C and C@t{++}
15106* C Checks:: C and C@t{++} type and range checks
c906108c 15107* Debugging C:: @value{GDBN} and C
79a6e687 15108* Debugging C Plus Plus:: @value{GDBN} features for C@t{++}
febe4383 15109* Decimal Floating Point:: Numbers in Decimal Floating Point format
c906108c 15110@end menu
c906108c 15111
6d2ebf8b 15112@node C Operators
79a6e687 15113@subsubsection C and C@t{++} Operators
7a292a7a 15114
b37052ae 15115@cindex C and C@t{++} operators
c906108c
SS
15116
15117Operators must be defined on values of specific types. For instance,
15118@code{+} is defined on numbers, but not on structures. Operators are
5d161b24 15119often defined on groups of types.
c906108c 15120
b37052ae 15121For the purposes of C and C@t{++}, the following definitions hold:
c906108c
SS
15122
15123@itemize @bullet
53a5351d 15124
c906108c 15125@item
c906108c 15126@emph{Integral types} include @code{int} with any of its storage-class
b37052ae 15127specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}.
c906108c
SS
15128
15129@item
d4f3574e
SS
15130@emph{Floating-point types} include @code{float}, @code{double}, and
15131@code{long double} (if supported by the target platform).
c906108c
SS
15132
15133@item
53a5351d 15134@emph{Pointer types} include all types defined as @code{(@var{type} *)}.
c906108c
SS
15135
15136@item
15137@emph{Scalar types} include all of the above.
53a5351d 15138
c906108c
SS
15139@end itemize
15140
15141@noindent
15142The following operators are supported. They are listed here
15143in order of increasing precedence:
15144
15145@table @code
15146@item ,
15147The comma or sequencing operator. Expressions in a comma-separated list
15148are evaluated from left to right, with the result of the entire
15149expression being the last expression evaluated.
15150
15151@item =
15152Assignment. The value of an assignment expression is the value
15153assigned. Defined on scalar types.
15154
15155@item @var{op}=
15156Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}},
15157and translated to @w{@code{@var{a} = @var{a op b}}}.
697aa1b7 15158@w{@code{@var{op}=}} and @code{=} have the same precedence. The operator
c906108c
SS
15159@var{op} is any one of the operators @code{|}, @code{^}, @code{&},
15160@code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}.
15161
15162@item ?:
15163The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought
697aa1b7
EZ
15164of as: if @var{a} then @var{b} else @var{c}. The argument @var{a}
15165should be of an integral type.
c906108c
SS
15166
15167@item ||
15168Logical @sc{or}. Defined on integral types.
15169
15170@item &&
15171Logical @sc{and}. Defined on integral types.
15172
15173@item |
15174Bitwise @sc{or}. Defined on integral types.
15175
15176@item ^
15177Bitwise exclusive-@sc{or}. Defined on integral types.
15178
15179@item &
15180Bitwise @sc{and}. Defined on integral types.
15181
15182@item ==@r{, }!=
15183Equality and inequality. Defined on scalar types. The value of these
15184expressions is 0 for false and non-zero for true.
15185
15186@item <@r{, }>@r{, }<=@r{, }>=
15187Less than, greater than, less than or equal, greater than or equal.
15188Defined on scalar types. The value of these expressions is 0 for false
15189and non-zero for true.
15190
15191@item <<@r{, }>>
15192left shift, and right shift. Defined on integral types.
15193
15194@item @@
15195The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
15196
15197@item +@r{, }-
15198Addition and subtraction. Defined on integral types, floating-point types and
15199pointer types.
15200
15201@item *@r{, }/@r{, }%
15202Multiplication, division, and modulus. Multiplication and division are
15203defined on integral and floating-point types. Modulus is defined on
15204integral types.
15205
15206@item ++@r{, }--
15207Increment and decrement. When appearing before a variable, the
15208operation is performed before the variable is used in an expression;
15209when appearing after it, the variable's value is used before the
15210operation takes place.
15211
15212@item *
15213Pointer dereferencing. Defined on pointer types. Same precedence as
15214@code{++}.
15215
15216@item &
15217Address operator. Defined on variables. Same precedence as @code{++}.
15218
b37052ae
EZ
15219For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is
15220allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})}
b17828ca 15221to examine the address
b37052ae 15222where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is
c906108c 15223stored.
c906108c
SS
15224
15225@item -
15226Negative. Defined on integral and floating-point types. Same
15227precedence as @code{++}.
15228
15229@item !
15230Logical negation. Defined on integral types. Same precedence as
15231@code{++}.
15232
15233@item ~
15234Bitwise complement operator. Defined on integral types. Same precedence as
15235@code{++}.
15236
15237
15238@item .@r{, }->
15239Structure member, and pointer-to-structure member. For convenience,
15240@value{GDBN} regards the two as equivalent, choosing whether to dereference a
15241pointer based on the stored type information.
15242Defined on @code{struct} and @code{union} data.
15243
c906108c
SS
15244@item .*@r{, }->*
15245Dereferences of pointers to members.
c906108c
SS
15246
15247@item []
15248Array indexing. @code{@var{a}[@var{i}]} is defined as
15249@code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
15250
15251@item ()
15252Function parameter list. Same precedence as @code{->}.
15253
c906108c 15254@item ::
b37052ae 15255C@t{++} scope resolution operator. Defined on @code{struct}, @code{union},
7a292a7a 15256and @code{class} types.
c906108c
SS
15257
15258@item ::
7a292a7a
SS
15259Doubled colons also represent the @value{GDBN} scope operator
15260(@pxref{Expressions, ,Expressions}). Same precedence as @code{::},
15261above.
c906108c
SS
15262@end table
15263
c906108c
SS
15264If an operator is redefined in the user code, @value{GDBN} usually
15265attempts to invoke the redefined version instead of using the operator's
15266predefined meaning.
c906108c 15267
6d2ebf8b 15268@node C Constants
79a6e687 15269@subsubsection C and C@t{++} Constants
c906108c 15270
b37052ae 15271@cindex C and C@t{++} constants
c906108c 15272
b37052ae 15273@value{GDBN} allows you to express the constants of C and C@t{++} in the
c906108c 15274following ways:
c906108c
SS
15275
15276@itemize @bullet
15277@item
15278Integer constants are a sequence of digits. Octal constants are
6ca652b0
EZ
15279specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants
15280by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter
c906108c
SS
15281@samp{l}, specifying that the constant should be treated as a
15282@code{long} value.
15283
15284@item
15285Floating point constants are a sequence of digits, followed by a decimal
15286point, followed by a sequence of digits, and optionally followed by an
15287exponent. An exponent is of the form:
15288@samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another
15289sequence of digits. The @samp{+} is optional for positive exponents.
d4f3574e
SS
15290A floating-point constant may also end with a letter @samp{f} or
15291@samp{F}, specifying that the constant should be treated as being of
15292the @code{float} (as opposed to the default @code{double}) type; or with
15293a letter @samp{l} or @samp{L}, which specifies a @code{long double}
15294constant.
c906108c
SS
15295
15296@item
15297Enumerated constants consist of enumerated identifiers, or their
15298integral equivalents.
15299
15300@item
15301Character constants are a single character surrounded by single quotes
15302(@code{'}), or a number---the ordinal value of the corresponding character
d4f3574e 15303(usually its @sc{ascii} value). Within quotes, the single character may
c906108c
SS
15304be represented by a letter or by @dfn{escape sequences}, which are of
15305the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation
15306of the character's ordinal value; or of the form @samp{\@var{x}}, where
15307@samp{@var{x}} is a predefined special character---for example,
15308@samp{\n} for newline.
15309
e0f8f636
TT
15310Wide character constants can be written by prefixing a character
15311constant with @samp{L}, as in C. For example, @samp{L'x'} is the wide
15312form of @samp{x}. The target wide character set is used when
15313computing the value of this constant (@pxref{Character Sets}).
15314
c906108c 15315@item
96a2c332
SS
15316String constants are a sequence of character constants surrounded by
15317double quotes (@code{"}). Any valid character constant (as described
15318above) may appear. Double quotes within the string must be preceded by
15319a backslash, so for instance @samp{"a\"b'c"} is a string of five
15320characters.
c906108c 15321
e0f8f636
TT
15322Wide string constants can be written by prefixing a string constant
15323with @samp{L}, as in C. The target wide character set is used when
15324computing the value of this constant (@pxref{Character Sets}).
15325
c906108c
SS
15326@item
15327Pointer constants are an integral value. You can also write pointers
15328to constants using the C operator @samp{&}.
15329
15330@item
15331Array constants are comma-separated lists surrounded by braces @samp{@{}
15332and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of
15333integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array,
15334and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers.
15335@end itemize
15336
79a6e687
BW
15337@node C Plus Plus Expressions
15338@subsubsection C@t{++} Expressions
b37052ae
EZ
15339
15340@cindex expressions in C@t{++}
15341@value{GDBN} expression handling can interpret most C@t{++} expressions.
15342
0179ffac
DC
15343@cindex debugging C@t{++} programs
15344@cindex C@t{++} compilers
15345@cindex debug formats and C@t{++}
15346@cindex @value{NGCC} and C@t{++}
c906108c 15347@quotation
e0f8f636
TT
15348@emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use
15349the proper compiler and the proper debug format. Currently,
15350@value{GDBN} works best when debugging C@t{++} code that is compiled
15351with the most recent version of @value{NGCC} possible. The DWARF
15352debugging format is preferred; @value{NGCC} defaults to this on most
15353popular platforms. Other compilers and/or debug formats are likely to
15354work badly or not at all when using @value{GDBN} to debug C@t{++}
15355code. @xref{Compilation}.
c906108c 15356@end quotation
c906108c
SS
15357
15358@enumerate
15359
15360@cindex member functions
15361@item
15362Member function calls are allowed; you can use expressions like
15363
474c8240 15364@smallexample
c906108c 15365count = aml->GetOriginal(x, y)
474c8240 15366@end smallexample
c906108c 15367
41afff9a 15368@vindex this@r{, inside C@t{++} member functions}
b37052ae 15369@cindex namespace in C@t{++}
c906108c
SS
15370@item
15371While a member function is active (in the selected stack frame), your
15372expressions have the same namespace available as the member function;
15373that is, @value{GDBN} allows implicit references to the class instance
e0f8f636
TT
15374pointer @code{this} following the same rules as C@t{++}. @code{using}
15375declarations in the current scope are also respected by @value{GDBN}.
c906108c 15376
c906108c 15377@cindex call overloaded functions
d4f3574e 15378@cindex overloaded functions, calling
b37052ae 15379@cindex type conversions in C@t{++}
c906108c
SS
15380@item
15381You can call overloaded functions; @value{GDBN} resolves the function
d4f3574e 15382call to the right definition, with some restrictions. @value{GDBN} does not
c906108c
SS
15383perform overload resolution involving user-defined type conversions,
15384calls to constructors, or instantiations of templates that do not exist
15385in the program. It also cannot handle ellipsis argument lists or
15386default arguments.
15387
15388It does perform integral conversions and promotions, floating-point
15389promotions, arithmetic conversions, pointer conversions, conversions of
15390class objects to base classes, and standard conversions such as those of
15391functions or arrays to pointers; it requires an exact match on the
15392number of function arguments.
15393
15394Overload resolution is always performed, unless you have specified
79a6e687
BW
15395@code{set overload-resolution off}. @xref{Debugging C Plus Plus,
15396,@value{GDBN} Features for C@t{++}}.
c906108c 15397
d4f3574e 15398You must specify @code{set overload-resolution off} in order to use an
c906108c
SS
15399explicit function signature to call an overloaded function, as in
15400@smallexample
15401p 'foo(char,int)'('x', 13)
15402@end smallexample
d4f3574e 15403
c906108c 15404The @value{GDBN} command-completion facility can simplify this;
79a6e687 15405see @ref{Completion, ,Command Completion}.
c906108c 15406
c906108c
SS
15407@cindex reference declarations
15408@item
c0f55cc6
AV
15409@value{GDBN} understands variables declared as C@t{++} lvalue or rvalue
15410references; you can use them in expressions just as you do in C@t{++}
15411source---they are automatically dereferenced.
c906108c
SS
15412
15413In the parameter list shown when @value{GDBN} displays a frame, the values of
15414reference variables are not displayed (unlike other variables); this
15415avoids clutter, since references are often used for large structures.
15416The @emph{address} of a reference variable is always shown, unless
15417you have specified @samp{set print address off}.
15418
15419@item
b37052ae 15420@value{GDBN} supports the C@t{++} name resolution operator @code{::}---your
c906108c
SS
15421expressions can use it just as expressions in your program do. Since
15422one scope may be defined in another, you can use @code{::} repeatedly if
15423necessary, for example in an expression like
15424@samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows
b37052ae 15425resolving name scope by reference to source files, in both C and C@t{++}
79a6e687 15426debugging (@pxref{Variables, ,Program Variables}).
c906108c 15427
e0f8f636
TT
15428@item
15429@value{GDBN} performs argument-dependent lookup, following the C@t{++}
15430specification.
15431@end enumerate
c906108c 15432
6d2ebf8b 15433@node C Defaults
79a6e687 15434@subsubsection C and C@t{++} Defaults
7a292a7a 15435
b37052ae 15436@cindex C and C@t{++} defaults
c906108c 15437
a451cb65
KS
15438If you allow @value{GDBN} to set range checking automatically, it
15439defaults to @code{off} whenever the working language changes to
b37052ae 15440C or C@t{++}. This happens regardless of whether you or @value{GDBN}
c906108c 15441selects the working language.
c906108c
SS
15442
15443If you allow @value{GDBN} to set the language automatically, it
15444recognizes source files whose names end with @file{.c}, @file{.C}, or
15445@file{.cc}, etc, and when @value{GDBN} enters code compiled from one of
b37052ae 15446these files, it sets the working language to C or C@t{++}.
79a6e687 15447@xref{Automatically, ,Having @value{GDBN} Infer the Source Language},
c906108c
SS
15448for further details.
15449
6d2ebf8b 15450@node C Checks
79a6e687 15451@subsubsection C and C@t{++} Type and Range Checks
7a292a7a 15452
b37052ae 15453@cindex C and C@t{++} checks
c906108c 15454
a451cb65
KS
15455By default, when @value{GDBN} parses C or C@t{++} expressions, strict type
15456checking is used. However, if you turn type checking off, @value{GDBN}
15457will allow certain non-standard conversions, such as promoting integer
15458constants to pointers.
c906108c
SS
15459
15460Range checking, if turned on, is done on mathematical operations. Array
15461indices are not checked, since they are often used to index a pointer
15462that is not itself an array.
c906108c 15463
6d2ebf8b 15464@node Debugging C
c906108c 15465@subsubsection @value{GDBN} and C
c906108c
SS
15466
15467The @code{set print union} and @code{show print union} commands apply to
15468the @code{union} type. When set to @samp{on}, any @code{union} that is
7a292a7a
SS
15469inside a @code{struct} or @code{class} is also printed. Otherwise, it
15470appears as @samp{@{...@}}.
c906108c
SS
15471
15472The @code{@@} operator aids in the debugging of dynamic arrays, formed
15473with pointers and a memory allocation function. @xref{Expressions,
15474,Expressions}.
15475
79a6e687
BW
15476@node Debugging C Plus Plus
15477@subsubsection @value{GDBN} Features for C@t{++}
c906108c 15478
b37052ae 15479@cindex commands for C@t{++}
7a292a7a 15480
b37052ae
EZ
15481Some @value{GDBN} commands are particularly useful with C@t{++}, and some are
15482designed specifically for use with C@t{++}. Here is a summary:
c906108c
SS
15483
15484@table @code
15485@cindex break in overloaded functions
15486@item @r{breakpoint menus}
15487When you want a breakpoint in a function whose name is overloaded,
6ba66d6a
JB
15488@value{GDBN} has the capability to display a menu of possible breakpoint
15489locations to help you specify which function definition you want.
15490@xref{Ambiguous Expressions,,Ambiguous Expressions}.
c906108c 15491
b37052ae 15492@cindex overloading in C@t{++}
c906108c
SS
15493@item rbreak @var{regex}
15494Setting breakpoints using regular expressions is helpful for setting
15495breakpoints on overloaded functions that are not members of any special
15496classes.
79a6e687 15497@xref{Set Breaks, ,Setting Breakpoints}.
c906108c 15498
b37052ae 15499@cindex C@t{++} exception handling
c906108c 15500@item catch throw
591f19e8 15501@itemx catch rethrow
c906108c 15502@itemx catch catch
b37052ae 15503Debug C@t{++} exception handling using these commands. @xref{Set
79a6e687 15504Catchpoints, , Setting Catchpoints}.
c906108c
SS
15505
15506@cindex inheritance
15507@item ptype @var{typename}
15508Print inheritance relationships as well as other information for type
15509@var{typename}.
15510@xref{Symbols, ,Examining the Symbol Table}.
15511
c4aeac85
TT
15512@item info vtbl @var{expression}.
15513The @code{info vtbl} command can be used to display the virtual
15514method tables of the object computed by @var{expression}. This shows
15515one entry per virtual table; there may be multiple virtual tables when
15516multiple inheritance is in use.
15517
439250fb
DE
15518@cindex C@t{++} demangling
15519@item demangle @var{name}
15520Demangle @var{name}.
15521@xref{Symbols}, for a more complete description of the @code{demangle} command.
15522
b37052ae 15523@cindex C@t{++} symbol display
c906108c
SS
15524@item set print demangle
15525@itemx show print demangle
15526@itemx set print asm-demangle
15527@itemx show print asm-demangle
b37052ae
EZ
15528Control whether C@t{++} symbols display in their source form, both when
15529displaying code as C@t{++} source and when displaying disassemblies.
79a6e687 15530@xref{Print Settings, ,Print Settings}.
c906108c
SS
15531
15532@item set print object
15533@itemx show print object
15534Choose whether to print derived (actual) or declared types of objects.
79a6e687 15535@xref{Print Settings, ,Print Settings}.
c906108c
SS
15536
15537@item set print vtbl
15538@itemx show print vtbl
15539Control the format for printing virtual function tables.
79a6e687 15540@xref{Print Settings, ,Print Settings}.
c906108c 15541(The @code{vtbl} commands do not work on programs compiled with the HP
b37052ae 15542ANSI C@t{++} compiler (@code{aCC}).)
c906108c
SS
15543
15544@kindex set overload-resolution
d4f3574e 15545@cindex overloaded functions, overload resolution
c906108c 15546@item set overload-resolution on
b37052ae 15547Enable overload resolution for C@t{++} expression evaluation. The default
c906108c
SS
15548is on. For overloaded functions, @value{GDBN} evaluates the arguments
15549and searches for a function whose signature matches the argument types,
79a6e687
BW
15550using the standard C@t{++} conversion rules (see @ref{C Plus Plus
15551Expressions, ,C@t{++} Expressions}, for details).
15552If it cannot find a match, it emits a message.
c906108c
SS
15553
15554@item set overload-resolution off
b37052ae 15555Disable overload resolution for C@t{++} expression evaluation. For
c906108c
SS
15556overloaded functions that are not class member functions, @value{GDBN}
15557chooses the first function of the specified name that it finds in the
15558symbol table, whether or not its arguments are of the correct type. For
15559overloaded functions that are class member functions, @value{GDBN}
15560searches for a function whose signature @emph{exactly} matches the
15561argument types.
c906108c 15562
9c16f35a
EZ
15563@kindex show overload-resolution
15564@item show overload-resolution
15565Show the current setting of overload resolution.
15566
c906108c
SS
15567@item @r{Overloaded symbol names}
15568You can specify a particular definition of an overloaded symbol, using
b37052ae 15569the same notation that is used to declare such symbols in C@t{++}: type
c906108c
SS
15570@code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can
15571also use the @value{GDBN} command-line word completion facilities to list the
15572available choices, or to finish the type list for you.
79a6e687 15573@xref{Completion,, Command Completion}, for details on how to do this.
bd69330d
PA
15574
15575@item @r{Breakpoints in functions with ABI tags}
15576
15577The GNU C@t{++} compiler introduced the notion of ABI ``tags'', which
15578correspond to changes in the ABI of a type, function, or variable that
15579would not otherwise be reflected in a mangled name. See
15580@url{https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/}
15581for more detail.
15582
15583The ABI tags are visible in C@t{++} demangled names. For example, a
15584function that returns a std::string:
15585
15586@smallexample
15587std::string function(int);
15588@end smallexample
15589
15590@noindent
15591when compiled for the C++11 ABI is marked with the @code{cxx11} ABI
15592tag, and @value{GDBN} displays the symbol like this:
15593
15594@smallexample
15595function[abi:cxx11](int)
15596@end smallexample
15597
15598You can set a breakpoint on such functions simply as if they had no
15599tag. For example:
15600
15601@smallexample
15602(gdb) b function(int)
15603Breakpoint 2 at 0x40060d: file main.cc, line 10.
15604(gdb) info breakpoints
15605Num Type Disp Enb Address What
156061 breakpoint keep y 0x0040060d in function[abi:cxx11](int)
15607 at main.cc:10
15608@end smallexample
15609
15610On the rare occasion you need to disambiguate between different ABI
15611tags, you can do so by simply including the ABI tag in the function
15612name, like:
15613
15614@smallexample
15615(@value{GDBP}) b ambiguous[abi:other_tag](int)
15616@end smallexample
c906108c 15617@end table
c906108c 15618
febe4383
TJB
15619@node Decimal Floating Point
15620@subsubsection Decimal Floating Point format
15621@cindex decimal floating point format
15622
15623@value{GDBN} can examine, set and perform computations with numbers in
15624decimal floating point format, which in the C language correspond to the
15625@code{_Decimal32}, @code{_Decimal64} and @code{_Decimal128} types as
15626specified by the extension to support decimal floating-point arithmetic.
15627
15628There are two encodings in use, depending on the architecture: BID (Binary
15629Integer Decimal) for x86 and x86-64, and DPD (Densely Packed Decimal) for
4ac33720
UW
15630PowerPC and S/390. @value{GDBN} will use the appropriate encoding for the
15631configured target.
febe4383
TJB
15632
15633Because of a limitation in @file{libdecnumber}, the library used by @value{GDBN}
15634to manipulate decimal floating point numbers, it is not possible to convert
15635(using a cast, for example) integers wider than 32-bit to decimal float.
15636
15637In addition, in order to imitate @value{GDBN}'s behaviour with binary floating
15638point computations, error checking in decimal float operations ignores
15639underflow, overflow and divide by zero exceptions.
15640
4acd40f3 15641In the PowerPC architecture, @value{GDBN} provides a set of pseudo-registers
99e008fe
EZ
15642to inspect @code{_Decimal128} values stored in floating point registers.
15643See @ref{PowerPC,,PowerPC} for more details.
4acd40f3 15644
6aecb9c2
JB
15645@node D
15646@subsection D
15647
15648@cindex D
15649@value{GDBN} can be used to debug programs written in D and compiled with
15650GDC, LDC or DMD compilers. Currently @value{GDBN} supports only one D
15651specific feature --- dynamic arrays.
15652
a766d390
DE
15653@node Go
15654@subsection Go
15655
15656@cindex Go (programming language)
15657@value{GDBN} can be used to debug programs written in Go and compiled with
15658@file{gccgo} or @file{6g} compilers.
15659
15660Here is a summary of the Go-specific features and restrictions:
15661
15662@table @code
15663@cindex current Go package
15664@item The current Go package
15665The name of the current package does not need to be specified when
15666specifying global variables and functions.
15667
15668For example, given the program:
15669
15670@example
15671package main
15672var myglob = "Shall we?"
15673func main () @{
15674 // ...
15675@}
15676@end example
15677
15678When stopped inside @code{main} either of these work:
15679
15680@example
15681(gdb) p myglob
15682(gdb) p main.myglob
15683@end example
15684
15685@cindex builtin Go types
15686@item Builtin Go types
15687The @code{string} type is recognized by @value{GDBN} and is printed
15688as a string.
15689
15690@cindex builtin Go functions
15691@item Builtin Go functions
15692The @value{GDBN} expression parser recognizes the @code{unsafe.Sizeof}
15693function and handles it internally.
a766d390
DE
15694
15695@cindex restrictions on Go expressions
15696@item Restrictions on Go expressions
15697All Go operators are supported except @code{&^}.
15698The Go @code{_} ``blank identifier'' is not supported.
15699Automatic dereferencing of pointers is not supported.
50f042b9 15700@end table
a766d390 15701
b37303ee
AF
15702@node Objective-C
15703@subsection Objective-C
15704
15705@cindex Objective-C
15706This section provides information about some commands and command
721c2651
EZ
15707options that are useful for debugging Objective-C code. See also
15708@ref{Symbols, info classes}, and @ref{Symbols, info selectors}, for a
15709few more commands specific to Objective-C support.
b37303ee
AF
15710
15711@menu
b383017d
RM
15712* Method Names in Commands::
15713* The Print Command with Objective-C::
b37303ee
AF
15714@end menu
15715
c8f4133a 15716@node Method Names in Commands
b37303ee
AF
15717@subsubsection Method Names in Commands
15718
15719The following commands have been extended to accept Objective-C method
15720names as line specifications:
15721
15722@kindex clear@r{, and Objective-C}
15723@kindex break@r{, and Objective-C}
15724@kindex info line@r{, and Objective-C}
15725@kindex jump@r{, and Objective-C}
15726@kindex list@r{, and Objective-C}
15727@itemize
15728@item @code{clear}
15729@item @code{break}
15730@item @code{info line}
15731@item @code{jump}
15732@item @code{list}
15733@end itemize
15734
15735A fully qualified Objective-C method name is specified as
15736
15737@smallexample
15738-[@var{Class} @var{methodName}]
15739@end smallexample
15740
c552b3bb
JM
15741where the minus sign is used to indicate an instance method and a
15742plus sign (not shown) is used to indicate a class method. The class
15743name @var{Class} and method name @var{methodName} are enclosed in
15744brackets, similar to the way messages are specified in Objective-C
15745source code. For example, to set a breakpoint at the @code{create}
15746instance method of class @code{Fruit} in the program currently being
15747debugged, enter:
b37303ee
AF
15748
15749@smallexample
15750break -[Fruit create]
15751@end smallexample
15752
15753To list ten program lines around the @code{initialize} class method,
15754enter:
15755
15756@smallexample
15757list +[NSText initialize]
15758@end smallexample
15759
c552b3bb
JM
15760In the current version of @value{GDBN}, the plus or minus sign is
15761required. In future versions of @value{GDBN}, the plus or minus
15762sign will be optional, but you can use it to narrow the search. It
15763is also possible to specify just a method name:
b37303ee
AF
15764
15765@smallexample
15766break create
15767@end smallexample
15768
15769You must specify the complete method name, including any colons. If
15770your program's source files contain more than one @code{create} method,
15771you'll be presented with a numbered list of classes that implement that
15772method. Indicate your choice by number, or type @samp{0} to exit if
15773none apply.
15774
15775As another example, to clear a breakpoint established at the
15776@code{makeKeyAndOrderFront:} method of the @code{NSWindow} class, enter:
15777
15778@smallexample
15779clear -[NSWindow makeKeyAndOrderFront:]
15780@end smallexample
15781
15782@node The Print Command with Objective-C
15783@subsubsection The Print Command With Objective-C
721c2651 15784@cindex Objective-C, print objects
c552b3bb
JM
15785@kindex print-object
15786@kindex po @r{(@code{print-object})}
b37303ee 15787
c552b3bb 15788The print command has also been extended to accept methods. For example:
b37303ee
AF
15789
15790@smallexample
c552b3bb 15791print -[@var{object} hash]
b37303ee
AF
15792@end smallexample
15793
15794@cindex print an Objective-C object description
c552b3bb
JM
15795@cindex @code{_NSPrintForDebugger}, and printing Objective-C objects
15796@noindent
15797will tell @value{GDBN} to send the @code{hash} message to @var{object}
15798and print the result. Also, an additional command has been added,
15799@code{print-object} or @code{po} for short, which is meant to print
15800the description of an object. However, this command may only work
15801with certain Objective-C libraries that have a particular hook
15802function, @code{_NSPrintForDebugger}, defined.
b37303ee 15803
f4b8a18d
KW
15804@node OpenCL C
15805@subsection OpenCL C
15806
15807@cindex OpenCL C
15808This section provides information about @value{GDBN}s OpenCL C support.
15809
15810@menu
15811* OpenCL C Datatypes::
15812* OpenCL C Expressions::
15813* OpenCL C Operators::
15814@end menu
15815
15816@node OpenCL C Datatypes
15817@subsubsection OpenCL C Datatypes
15818
15819@cindex OpenCL C Datatypes
15820@value{GDBN} supports the builtin scalar and vector datatypes specified
15821by OpenCL 1.1. In addition the half- and double-precision floating point
15822data types of the @code{cl_khr_fp16} and @code{cl_khr_fp64} OpenCL
15823extensions are also known to @value{GDBN}.
15824
15825@node OpenCL C Expressions
15826@subsubsection OpenCL C Expressions
15827
15828@cindex OpenCL C Expressions
15829@value{GDBN} supports accesses to vector components including the access as
15830lvalue where possible. Since OpenCL C is based on C99 most C expressions
15831supported by @value{GDBN} can be used as well.
15832
15833@node OpenCL C Operators
15834@subsubsection OpenCL C Operators
15835
15836@cindex OpenCL C Operators
15837@value{GDBN} supports the operators specified by OpenCL 1.1 for scalar and
15838vector data types.
15839
09d4efe1
EZ
15840@node Fortran
15841@subsection Fortran
15842@cindex Fortran-specific support in @value{GDBN}
15843
814e32d7
WZ
15844@value{GDBN} can be used to debug programs written in Fortran, but it
15845currently supports only the features of Fortran 77 language.
15846
15847@cindex trailing underscore, in Fortran symbols
15848Some Fortran compilers (@sc{gnu} Fortran 77 and Fortran 95 compilers
15849among them) append an underscore to the names of variables and
15850functions. When you debug programs compiled by those compilers, you
15851will need to refer to variables and functions with a trailing
15852underscore.
15853
15854@menu
15855* Fortran Operators:: Fortran operators and expressions
15856* Fortran Defaults:: Default settings for Fortran
79a6e687 15857* Special Fortran Commands:: Special @value{GDBN} commands for Fortran
814e32d7
WZ
15858@end menu
15859
15860@node Fortran Operators
79a6e687 15861@subsubsection Fortran Operators and Expressions
814e32d7
WZ
15862
15863@cindex Fortran operators and expressions
15864
15865Operators must be defined on values of specific types. For instance,
15866@code{+} is defined on numbers, but not on characters or other non-
ff2587ec 15867arithmetic types. Operators are often defined on groups of types.
814e32d7
WZ
15868
15869@table @code
15870@item **
99e008fe 15871The exponentiation operator. It raises the first operand to the power
814e32d7
WZ
15872of the second one.
15873
15874@item :
15875The range operator. Normally used in the form of array(low:high) to
15876represent a section of array.
68837c9d
MD
15877
15878@item %
15879The access component operator. Normally used to access elements in derived
15880types. Also suitable for unions. As unions aren't part of regular Fortran,
15881this can only happen when accessing a register that uses a gdbarch-defined
15882union type.
814e32d7
WZ
15883@end table
15884
15885@node Fortran Defaults
15886@subsubsection Fortran Defaults
15887
15888@cindex Fortran Defaults
15889
15890Fortran symbols are usually case-insensitive, so @value{GDBN} by
15891default uses case-insensitive matches for Fortran symbols. You can
15892change that with the @samp{set case-insensitive} command, see
15893@ref{Symbols}, for the details.
15894
79a6e687
BW
15895@node Special Fortran Commands
15896@subsubsection Special Fortran Commands
814e32d7
WZ
15897
15898@cindex Special Fortran commands
15899
db2e3e2e
BW
15900@value{GDBN} has some commands to support Fortran-specific features,
15901such as displaying common blocks.
814e32d7 15902
09d4efe1
EZ
15903@table @code
15904@cindex @code{COMMON} blocks, Fortran
15905@kindex info common
15906@item info common @r{[}@var{common-name}@r{]}
15907This command prints the values contained in the Fortran @code{COMMON}
15908block whose name is @var{common-name}. With no argument, the names of
d52fb0e9 15909all @code{COMMON} blocks visible at the current program location are
09d4efe1
EZ
15910printed.
15911@end table
15912
9c16f35a
EZ
15913@node Pascal
15914@subsection Pascal
15915
15916@cindex Pascal support in @value{GDBN}, limitations
15917Debugging Pascal programs which use sets, subranges, file variables, or
15918nested functions does not currently work. @value{GDBN} does not support
15919entering expressions, printing values, or similar features using Pascal
15920syntax.
15921
15922The Pascal-specific command @code{set print pascal_static-members}
15923controls whether static members of Pascal objects are displayed.
15924@xref{Print Settings, pascal_static-members}.
15925
0bdfa368
TT
15926@node Rust
15927@subsection Rust
15928
15929@value{GDBN} supports the @url{https://www.rust-lang.org/, Rust
15930Programming Language}. Type- and value-printing, and expression
15931parsing, are reasonably complete. However, there are a few
15932peculiarities and holes to be aware of.
15933
15934@itemize @bullet
15935@item
15936Linespecs (@pxref{Specify Location}) are never relative to the current
15937crate. Instead, they act as if there were a global namespace of
15938crates, somewhat similar to the way @code{extern crate} behaves.
15939
15940That is, if @value{GDBN} is stopped at a breakpoint in a function in
15941crate @samp{A}, module @samp{B}, then @code{break B::f} will attempt
15942to set a breakpoint in a function named @samp{f} in a crate named
15943@samp{B}.
15944
15945As a consequence of this approach, linespecs also cannot refer to
15946items using @samp{self::} or @samp{super::}.
15947
15948@item
15949Because @value{GDBN} implements Rust name-lookup semantics in
15950expressions, it will sometimes prepend the current crate to a name.
15951For example, if @value{GDBN} is stopped at a breakpoint in the crate
15952@samp{K}, then @code{print ::x::y} will try to find the symbol
15953@samp{K::x::y}.
15954
15955However, since it is useful to be able to refer to other crates when
15956debugging, @value{GDBN} provides the @code{extern} extension to
15957circumvent this. To use the extension, just put @code{extern} before
15958a path expression to refer to the otherwise unavailable ``global''
15959scope.
15960
15961In the above example, if you wanted to refer to the symbol @samp{y} in
15962the crate @samp{x}, you would use @code{print extern x::y}.
15963
15964@item
15965The Rust expression evaluator does not support ``statement-like''
15966expressions such as @code{if} or @code{match}, or lambda expressions.
15967
15968@item
15969Tuple expressions are not implemented.
15970
15971@item
15972The Rust expression evaluator does not currently implement the
15973@code{Drop} trait. Objects that may be created by the evaluator will
15974never be destroyed.
15975
15976@item
15977@value{GDBN} does not implement type inference for generics. In order
15978to call generic functions or otherwise refer to generic items, you
15979will have to specify the type parameters manually.
15980
15981@item
15982@value{GDBN} currently uses the C@t{++} demangler for Rust. In most
15983cases this does not cause any problems. However, in an expression
15984context, completing a generic function name will give syntactically
15985invalid results. This happens because Rust requires the @samp{::}
15986operator between the function name and its generic arguments. For
15987example, @value{GDBN} might provide a completion like
15988@code{crate::f<u32>}, where the parser would require
15989@code{crate::f::<u32>}.
15990
15991@item
15992As of this writing, the Rust compiler (version 1.8) has a few holes in
15993the debugging information it generates. These holes prevent certain
15994features from being implemented by @value{GDBN}:
15995@itemize @bullet
15996
15997@item
15998Method calls cannot be made via traits.
15999
0bdfa368
TT
16000@item
16001Operator overloading is not implemented.
16002
16003@item
16004When debugging in a monomorphized function, you cannot use the generic
16005type names.
16006
16007@item
16008The type @code{Self} is not available.
16009
16010@item
16011@code{use} statements are not available, so some names may not be
16012available in the crate.
16013@end itemize
16014@end itemize
16015
09d4efe1 16016@node Modula-2
c906108c 16017@subsection Modula-2
7a292a7a 16018
d4f3574e 16019@cindex Modula-2, @value{GDBN} support
c906108c
SS
16020
16021The extensions made to @value{GDBN} to support Modula-2 only support
16022output from the @sc{gnu} Modula-2 compiler (which is currently being
16023developed). Other Modula-2 compilers are not currently supported, and
16024attempting to debug executables produced by them is most likely
16025to give an error as @value{GDBN} reads in the executable's symbol
16026table.
16027
16028@cindex expressions in Modula-2
16029@menu
16030* M2 Operators:: Built-in operators
16031* Built-In Func/Proc:: Built-in functions and procedures
16032* M2 Constants:: Modula-2 constants
72019c9c 16033* M2 Types:: Modula-2 types
c906108c
SS
16034* M2 Defaults:: Default settings for Modula-2
16035* Deviations:: Deviations from standard Modula-2
16036* M2 Checks:: Modula-2 type and range checks
16037* M2 Scope:: The scope operators @code{::} and @code{.}
16038* GDB/M2:: @value{GDBN} and Modula-2
16039@end menu
16040
6d2ebf8b 16041@node M2 Operators
c906108c
SS
16042@subsubsection Operators
16043@cindex Modula-2 operators
16044
16045Operators must be defined on values of specific types. For instance,
16046@code{+} is defined on numbers, but not on structures. Operators are
16047often defined on groups of types. For the purposes of Modula-2, the
16048following definitions hold:
16049
16050@itemize @bullet
16051
16052@item
16053@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
16054their subranges.
16055
16056@item
16057@emph{Character types} consist of @code{CHAR} and its subranges.
16058
16059@item
16060@emph{Floating-point types} consist of @code{REAL}.
16061
16062@item
16063@emph{Pointer types} consist of anything declared as @code{POINTER TO
16064@var{type}}.
16065
16066@item
16067@emph{Scalar types} consist of all of the above.
16068
16069@item
16070@emph{Set types} consist of @code{SET} and @code{BITSET} types.
16071
16072@item
16073@emph{Boolean types} consist of @code{BOOLEAN}.
16074@end itemize
16075
16076@noindent
16077The following operators are supported, and appear in order of
16078increasing precedence:
16079
16080@table @code
16081@item ,
16082Function argument or array index separator.
16083
16084@item :=
16085Assignment. The value of @var{var} @code{:=} @var{value} is
16086@var{value}.
16087
16088@item <@r{, }>
16089Less than, greater than on integral, floating-point, or enumerated
16090types.
16091
16092@item <=@r{, }>=
96a2c332 16093Less than or equal to, greater than or equal to
c906108c
SS
16094on integral, floating-point and enumerated types, or set inclusion on
16095set types. Same precedence as @code{<}.
16096
16097@item =@r{, }<>@r{, }#
16098Equality and two ways of expressing inequality, valid on scalar types.
16099Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is
16100available for inequality, since @code{#} conflicts with the script
16101comment character.
16102
16103@item IN
16104Set membership. Defined on set types and the types of their members.
16105Same precedence as @code{<}.
16106
16107@item OR
16108Boolean disjunction. Defined on boolean types.
16109
16110@item AND@r{, }&
d4f3574e 16111Boolean conjunction. Defined on boolean types.
c906108c
SS
16112
16113@item @@
16114The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
16115
16116@item +@r{, }-
16117Addition and subtraction on integral and floating-point types, or union
16118and difference on set types.
16119
16120@item *
16121Multiplication on integral and floating-point types, or set intersection
16122on set types.
16123
16124@item /
16125Division on floating-point types, or symmetric set difference on set
16126types. Same precedence as @code{*}.
16127
16128@item DIV@r{, }MOD
16129Integer division and remainder. Defined on integral types. Same
16130precedence as @code{*}.
16131
16132@item -
99e008fe 16133Negative. Defined on @code{INTEGER} and @code{REAL} data.
c906108c
SS
16134
16135@item ^
16136Pointer dereferencing. Defined on pointer types.
16137
16138@item NOT
16139Boolean negation. Defined on boolean types. Same precedence as
16140@code{^}.
16141
16142@item .
16143@code{RECORD} field selector. Defined on @code{RECORD} data. Same
16144precedence as @code{^}.
16145
16146@item []
16147Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}.
16148
16149@item ()
16150Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence
16151as @code{^}.
16152
16153@item ::@r{, }.
16154@value{GDBN} and Modula-2 scope operators.
16155@end table
16156
16157@quotation
72019c9c 16158@emph{Warning:} Set expressions and their operations are not yet supported, so @value{GDBN}
c906108c
SS
16159treats the use of the operator @code{IN}, or the use of operators
16160@code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#},
16161@code{<=}, and @code{>=} on sets as an error.
16162@end quotation
16163
cb51c4e0 16164
6d2ebf8b 16165@node Built-In Func/Proc
79a6e687 16166@subsubsection Built-in Functions and Procedures
cb51c4e0 16167@cindex Modula-2 built-ins
c906108c
SS
16168
16169Modula-2 also makes available several built-in procedures and functions.
16170In describing these, the following metavariables are used:
16171
16172@table @var
16173
16174@item a
16175represents an @code{ARRAY} variable.
16176
16177@item c
16178represents a @code{CHAR} constant or variable.
16179
16180@item i
16181represents a variable or constant of integral type.
16182
16183@item m
16184represents an identifier that belongs to a set. Generally used in the
16185same function with the metavariable @var{s}. The type of @var{s} should
16186be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}).
16187
16188@item n
16189represents a variable or constant of integral or floating-point type.
16190
16191@item r
16192represents a variable or constant of floating-point type.
16193
16194@item t
16195represents a type.
16196
16197@item v
16198represents a variable.
16199
16200@item x
16201represents a variable or constant of one of many types. See the
16202explanation of the function for details.
16203@end table
16204
16205All Modula-2 built-in procedures also return a result, described below.
16206
16207@table @code
16208@item ABS(@var{n})
16209Returns the absolute value of @var{n}.
16210
16211@item CAP(@var{c})
16212If @var{c} is a lower case letter, it returns its upper case
c3f6f71d 16213equivalent, otherwise it returns its argument.
c906108c
SS
16214
16215@item CHR(@var{i})
16216Returns the character whose ordinal value is @var{i}.
16217
16218@item DEC(@var{v})
c3f6f71d 16219Decrements the value in the variable @var{v} by one. Returns the new value.
c906108c
SS
16220
16221@item DEC(@var{v},@var{i})
16222Decrements the value in the variable @var{v} by @var{i}. Returns the
16223new value.
16224
16225@item EXCL(@var{m},@var{s})
16226Removes the element @var{m} from the set @var{s}. Returns the new
16227set.
16228
16229@item FLOAT(@var{i})
16230Returns the floating point equivalent of the integer @var{i}.
16231
16232@item HIGH(@var{a})
16233Returns the index of the last member of @var{a}.
16234
16235@item INC(@var{v})
c3f6f71d 16236Increments the value in the variable @var{v} by one. Returns the new value.
c906108c
SS
16237
16238@item INC(@var{v},@var{i})
16239Increments the value in the variable @var{v} by @var{i}. Returns the
16240new value.
16241
16242@item INCL(@var{m},@var{s})
16243Adds the element @var{m} to the set @var{s} if it is not already
16244there. Returns the new set.
16245
16246@item MAX(@var{t})
16247Returns the maximum value of the type @var{t}.
16248
16249@item MIN(@var{t})
16250Returns the minimum value of the type @var{t}.
16251
16252@item ODD(@var{i})
16253Returns boolean TRUE if @var{i} is an odd number.
16254
16255@item ORD(@var{x})
16256Returns the ordinal value of its argument. For example, the ordinal
697aa1b7
EZ
16257value of a character is its @sc{ascii} value (on machines supporting
16258the @sc{ascii} character set). The argument @var{x} must be of an
16259ordered type, which include integral, character and enumerated types.
c906108c
SS
16260
16261@item SIZE(@var{x})
697aa1b7
EZ
16262Returns the size of its argument. The argument @var{x} can be a
16263variable or a type.
c906108c
SS
16264
16265@item TRUNC(@var{r})
16266Returns the integral part of @var{r}.
16267
844781a1 16268@item TSIZE(@var{x})
697aa1b7
EZ
16269Returns the size of its argument. The argument @var{x} can be a
16270variable or a type.
844781a1 16271
c906108c
SS
16272@item VAL(@var{t},@var{i})
16273Returns the member of the type @var{t} whose ordinal value is @var{i}.
16274@end table
16275
16276@quotation
16277@emph{Warning:} Sets and their operations are not yet supported, so
16278@value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as
16279an error.
16280@end quotation
16281
16282@cindex Modula-2 constants
6d2ebf8b 16283@node M2 Constants
c906108c
SS
16284@subsubsection Constants
16285
16286@value{GDBN} allows you to express the constants of Modula-2 in the following
16287ways:
16288
16289@itemize @bullet
16290
16291@item
16292Integer constants are simply a sequence of digits. When used in an
16293expression, a constant is interpreted to be type-compatible with the
16294rest of the expression. Hexadecimal integers are specified by a
16295trailing @samp{H}, and octal integers by a trailing @samp{B}.
16296
16297@item
16298Floating point constants appear as a sequence of digits, followed by a
16299decimal point and another sequence of digits. An optional exponent can
16300then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where
16301@samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the
16302digits of the floating point constant must be valid decimal (base 10)
16303digits.
16304
16305@item
16306Character constants consist of a single character enclosed by a pair of
16307like quotes, either single (@code{'}) or double (@code{"}). They may
c3f6f71d 16308also be expressed by their ordinal value (their @sc{ascii} value, usually)
c906108c
SS
16309followed by a @samp{C}.
16310
16311@item
16312String constants consist of a sequence of characters enclosed by a
16313pair of like quotes, either single (@code{'}) or double (@code{"}).
16314Escape sequences in the style of C are also allowed. @xref{C
79a6e687 16315Constants, ,C and C@t{++} Constants}, for a brief explanation of escape
c906108c
SS
16316sequences.
16317
16318@item
16319Enumerated constants consist of an enumerated identifier.
16320
16321@item
16322Boolean constants consist of the identifiers @code{TRUE} and
16323@code{FALSE}.
16324
16325@item
16326Pointer constants consist of integral values only.
16327
16328@item
16329Set constants are not yet supported.
16330@end itemize
16331
72019c9c
GM
16332@node M2 Types
16333@subsubsection Modula-2 Types
16334@cindex Modula-2 types
16335
16336Currently @value{GDBN} can print the following data types in Modula-2
16337syntax: array types, record types, set types, pointer types, procedure
16338types, enumerated types, subrange types and base types. You can also
16339print the contents of variables declared using these type.
16340This section gives a number of simple source code examples together with
16341sample @value{GDBN} sessions.
16342
16343The first example contains the following section of code:
16344
16345@smallexample
16346VAR
16347 s: SET OF CHAR ;
16348 r: [20..40] ;
16349@end smallexample
16350
16351@noindent
16352and you can request @value{GDBN} to interrogate the type and value of
16353@code{r} and @code{s}.
16354
16355@smallexample
16356(@value{GDBP}) print s
16357@{'A'..'C', 'Z'@}
16358(@value{GDBP}) ptype s
16359SET OF CHAR
16360(@value{GDBP}) print r
1636121
16362(@value{GDBP}) ptype r
16363[20..40]
16364@end smallexample
16365
16366@noindent
16367Likewise if your source code declares @code{s} as:
16368
16369@smallexample
16370VAR
16371 s: SET ['A'..'Z'] ;
16372@end smallexample
16373
16374@noindent
16375then you may query the type of @code{s} by:
16376
16377@smallexample
16378(@value{GDBP}) ptype s
16379type = SET ['A'..'Z']
16380@end smallexample
16381
16382@noindent
16383Note that at present you cannot interactively manipulate set
16384expressions using the debugger.
16385
16386The following example shows how you might declare an array in Modula-2
16387and how you can interact with @value{GDBN} to print its type and contents:
16388
16389@smallexample
16390VAR
16391 s: ARRAY [-10..10] OF CHAR ;
16392@end smallexample
16393
16394@smallexample
16395(@value{GDBP}) ptype s
16396ARRAY [-10..10] OF CHAR
16397@end smallexample
16398
16399Note that the array handling is not yet complete and although the type
16400is printed correctly, expression handling still assumes that all
16401arrays have a lower bound of zero and not @code{-10} as in the example
844781a1 16402above.
72019c9c
GM
16403
16404Here are some more type related Modula-2 examples:
16405
16406@smallexample
16407TYPE
16408 colour = (blue, red, yellow, green) ;
16409 t = [blue..yellow] ;
16410VAR
16411 s: t ;
16412BEGIN
16413 s := blue ;
16414@end smallexample
16415
16416@noindent
16417The @value{GDBN} interaction shows how you can query the data type
16418and value of a variable.
16419
16420@smallexample
16421(@value{GDBP}) print s
16422$1 = blue
16423(@value{GDBP}) ptype t
16424type = [blue..yellow]
16425@end smallexample
16426
16427@noindent
16428In this example a Modula-2 array is declared and its contents
16429displayed. Observe that the contents are written in the same way as
16430their @code{C} counterparts.
16431
16432@smallexample
16433VAR
16434 s: ARRAY [1..5] OF CARDINAL ;
16435BEGIN
16436 s[1] := 1 ;
16437@end smallexample
16438
16439@smallexample
16440(@value{GDBP}) print s
16441$1 = @{1, 0, 0, 0, 0@}
16442(@value{GDBP}) ptype s
16443type = ARRAY [1..5] OF CARDINAL
16444@end smallexample
16445
16446The Modula-2 language interface to @value{GDBN} also understands
16447pointer types as shown in this example:
16448
16449@smallexample
16450VAR
16451 s: POINTER TO ARRAY [1..5] OF CARDINAL ;
16452BEGIN
16453 NEW(s) ;
16454 s^[1] := 1 ;
16455@end smallexample
16456
16457@noindent
16458and you can request that @value{GDBN} describes the type of @code{s}.
16459
16460@smallexample
16461(@value{GDBP}) ptype s
16462type = POINTER TO ARRAY [1..5] OF CARDINAL
16463@end smallexample
16464
16465@value{GDBN} handles compound types as we can see in this example.
16466Here we combine array types, record types, pointer types and subrange
16467types:
16468
16469@smallexample
16470TYPE
16471 foo = RECORD
16472 f1: CARDINAL ;
16473 f2: CHAR ;
16474 f3: myarray ;
16475 END ;
16476
16477 myarray = ARRAY myrange OF CARDINAL ;
16478 myrange = [-2..2] ;
16479VAR
16480 s: POINTER TO ARRAY myrange OF foo ;
16481@end smallexample
16482
16483@noindent
16484and you can ask @value{GDBN} to describe the type of @code{s} as shown
16485below.
16486
16487@smallexample
16488(@value{GDBP}) ptype s
16489type = POINTER TO ARRAY [-2..2] OF foo = RECORD
16490 f1 : CARDINAL;
16491 f2 : CHAR;
16492 f3 : ARRAY [-2..2] OF CARDINAL;
16493END
16494@end smallexample
16495
6d2ebf8b 16496@node M2 Defaults
79a6e687 16497@subsubsection Modula-2 Defaults
c906108c
SS
16498@cindex Modula-2 defaults
16499
16500If type and range checking are set automatically by @value{GDBN}, they
16501both default to @code{on} whenever the working language changes to
d4f3574e 16502Modula-2. This happens regardless of whether you or @value{GDBN}
c906108c
SS
16503selected the working language.
16504
16505If you allow @value{GDBN} to set the language automatically, then entering
16506code compiled from a file whose name ends with @file{.mod} sets the
79a6e687
BW
16507working language to Modula-2. @xref{Automatically, ,Having @value{GDBN}
16508Infer the Source Language}, for further details.
c906108c 16509
6d2ebf8b 16510@node Deviations
79a6e687 16511@subsubsection Deviations from Standard Modula-2
c906108c
SS
16512@cindex Modula-2, deviations from
16513
16514A few changes have been made to make Modula-2 programs easier to debug.
16515This is done primarily via loosening its type strictness:
16516
16517@itemize @bullet
16518@item
16519Unlike in standard Modula-2, pointer constants can be formed by
16520integers. This allows you to modify pointer variables during
16521debugging. (In standard Modula-2, the actual address contained in a
16522pointer variable is hidden from you; it can only be modified
16523through direct assignment to another pointer variable or expression that
16524returned a pointer.)
16525
16526@item
16527C escape sequences can be used in strings and characters to represent
16528non-printable characters. @value{GDBN} prints out strings with these
16529escape sequences embedded. Single non-printable characters are
16530printed using the @samp{CHR(@var{nnn})} format.
16531
16532@item
16533The assignment operator (@code{:=}) returns the value of its right-hand
16534argument.
16535
16536@item
16537All built-in procedures both modify @emph{and} return their argument.
16538@end itemize
16539
6d2ebf8b 16540@node M2 Checks
79a6e687 16541@subsubsection Modula-2 Type and Range Checks
c906108c
SS
16542@cindex Modula-2 checks
16543
16544@quotation
16545@emph{Warning:} in this release, @value{GDBN} does not yet perform type or
16546range checking.
16547@end quotation
16548@c FIXME remove warning when type/range checks added
16549
16550@value{GDBN} considers two Modula-2 variables type equivalent if:
16551
16552@itemize @bullet
16553@item
16554They are of types that have been declared equivalent via a @code{TYPE
16555@var{t1} = @var{t2}} statement
16556
16557@item
16558They have been declared on the same line. (Note: This is true of the
16559@sc{gnu} Modula-2 compiler, but it may not be true of other compilers.)
16560@end itemize
16561
16562As long as type checking is enabled, any attempt to combine variables
16563whose types are not equivalent is an error.
16564
16565Range checking is done on all mathematical operations, assignment, array
16566index bounds, and all built-in functions and procedures.
16567
6d2ebf8b 16568@node M2 Scope
79a6e687 16569@subsubsection The Scope Operators @code{::} and @code{.}
c906108c 16570@cindex scope
41afff9a 16571@cindex @code{.}, Modula-2 scope operator
c906108c
SS
16572@cindex colon, doubled as scope operator
16573@ifinfo
41afff9a 16574@vindex colon-colon@r{, in Modula-2}
c906108c
SS
16575@c Info cannot handle :: but TeX can.
16576@end ifinfo
a67ec3f4 16577@ifnotinfo
41afff9a 16578@vindex ::@r{, in Modula-2}
a67ec3f4 16579@end ifnotinfo
c906108c
SS
16580
16581There are a few subtle differences between the Modula-2 scope operator
16582(@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have
16583similar syntax:
16584
474c8240 16585@smallexample
c906108c
SS
16586
16587@var{module} . @var{id}
16588@var{scope} :: @var{id}
474c8240 16589@end smallexample
c906108c
SS
16590
16591@noindent
16592where @var{scope} is the name of a module or a procedure,
16593@var{module} the name of a module, and @var{id} is any declared
16594identifier within your program, except another module.
16595
16596Using the @code{::} operator makes @value{GDBN} search the scope
16597specified by @var{scope} for the identifier @var{id}. If it is not
16598found in the specified scope, then @value{GDBN} searches all scopes
16599enclosing the one specified by @var{scope}.
16600
16601Using the @code{.} operator makes @value{GDBN} search the current scope for
16602the identifier specified by @var{id} that was imported from the
16603definition module specified by @var{module}. With this operator, it is
16604an error if the identifier @var{id} was not imported from definition
16605module @var{module}, or if @var{id} is not an identifier in
16606@var{module}.
16607
6d2ebf8b 16608@node GDB/M2
c906108c
SS
16609@subsubsection @value{GDBN} and Modula-2
16610
16611Some @value{GDBN} commands have little use when debugging Modula-2 programs.
16612Five subcommands of @code{set print} and @code{show print} apply
b37052ae 16613specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle},
c906108c 16614@samp{asm-demangle}, @samp{object}, and @samp{union}. The first four
b37052ae 16615apply to C@t{++}, and the last to the C @code{union} type, which has no direct
c906108c
SS
16616analogue in Modula-2.
16617
16618The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available
d4f3574e 16619with any language, is not useful with Modula-2. Its
c906108c 16620intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be
b37052ae 16621created in Modula-2 as they can in C or C@t{++}. However, because an
c906108c 16622address can be specified by an integral constant, the construct
d4f3574e 16623@samp{@{@var{type}@}@var{adrexp}} is still useful.
c906108c
SS
16624
16625@cindex @code{#} in Modula-2
16626In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is
16627interpreted as the beginning of a comment. Use @code{<>} instead.
c906108c 16628
e07c999f
PH
16629@node Ada
16630@subsection Ada
16631@cindex Ada
16632
16633The extensions made to @value{GDBN} for Ada only support
16634output from the @sc{gnu} Ada (GNAT) compiler.
16635Other Ada compilers are not currently supported, and
16636attempting to debug executables produced by them is most likely
16637to be difficult.
16638
16639
16640@cindex expressions in Ada
16641@menu
16642* Ada Mode Intro:: General remarks on the Ada syntax
16643 and semantics supported by Ada mode
16644 in @value{GDBN}.
16645* Omissions from Ada:: Restrictions on the Ada expression syntax.
16646* Additions to Ada:: Extensions of the Ada expression syntax.
3685b09f
PMR
16647* Overloading support for Ada:: Support for expressions involving overloaded
16648 subprograms.
e07c999f 16649* Stopping Before Main Program:: Debugging the program during elaboration.
58d06528 16650* Ada Exceptions:: Ada Exceptions
20924a55
JB
16651* Ada Tasks:: Listing and setting breakpoints in tasks.
16652* Ada Tasks and Core Files:: Tasking Support when Debugging Core Files
6e1bb179
JB
16653* Ravenscar Profile:: Tasking Support when using the Ravenscar
16654 Profile
3fcded8f 16655* Ada Settings:: New settable GDB parameters for Ada.
e07c999f
PH
16656* Ada Glitches:: Known peculiarities of Ada mode.
16657@end menu
16658
16659@node Ada Mode Intro
16660@subsubsection Introduction
16661@cindex Ada mode, general
16662
16663The Ada mode of @value{GDBN} supports a fairly large subset of Ada expression
16664syntax, with some extensions.
16665The philosophy behind the design of this subset is
16666
16667@itemize @bullet
16668@item
16669That @value{GDBN} should provide basic literals and access to operations for
16670arithmetic, dereferencing, field selection, indexing, and subprogram calls,
16671leaving more sophisticated computations to subprograms written into the
16672program (which therefore may be called from @value{GDBN}).
16673
16674@item
16675That type safety and strict adherence to Ada language restrictions
16676are not particularly important to the @value{GDBN} user.
16677
16678@item
16679That brevity is important to the @value{GDBN} user.
16680@end itemize
16681
f3a2dd1a
JB
16682Thus, for brevity, the debugger acts as if all names declared in
16683user-written packages are directly visible, even if they are not visible
16684according to Ada rules, thus making it unnecessary to fully qualify most
16685names with their packages, regardless of context. Where this causes
16686ambiguity, @value{GDBN} asks the user's intent.
e07c999f
PH
16687
16688The debugger will start in Ada mode if it detects an Ada main program.
16689As for other languages, it will enter Ada mode when stopped in a program that
16690was translated from an Ada source file.
16691
16692While in Ada mode, you may use `@t{--}' for comments. This is useful
16693mostly for documenting command files. The standard @value{GDBN} comment
16694(@samp{#}) still works at the beginning of a line in Ada mode, but not in the
16695middle (to allow based literals).
16696
e07c999f
PH
16697@node Omissions from Ada
16698@subsubsection Omissions from Ada
16699@cindex Ada, omissions from
16700
16701Here are the notable omissions from the subset:
16702
16703@itemize @bullet
16704@item
16705Only a subset of the attributes are supported:
16706
16707@itemize @minus
16708@item
16709@t{'First}, @t{'Last}, and @t{'Length}
16710 on array objects (not on types and subtypes).
16711
16712@item
16713@t{'Min} and @t{'Max}.
16714
16715@item
16716@t{'Pos} and @t{'Val}.
16717
16718@item
16719@t{'Tag}.
16720
16721@item
16722@t{'Range} on array objects (not subtypes), but only as the right
16723operand of the membership (@code{in}) operator.
16724
16725@item
16726@t{'Access}, @t{'Unchecked_Access}, and
16727@t{'Unrestricted_Access} (a GNAT extension).
16728
16729@item
16730@t{'Address}.
16731@end itemize
16732
16733@item
16734The names in
16735@code{Characters.Latin_1} are not available and
16736concatenation is not implemented. Thus, escape characters in strings are
16737not currently available.
16738
16739@item
16740Equality tests (@samp{=} and @samp{/=}) on arrays test for bitwise
16741equality of representations. They will generally work correctly
16742for strings and arrays whose elements have integer or enumeration types.
16743They may not work correctly for arrays whose element
16744types have user-defined equality, for arrays of real values
16745(in particular, IEEE-conformant floating point, because of negative
16746zeroes and NaNs), and for arrays whose elements contain unused bits with
16747indeterminate values.
16748
16749@item
16750The other component-by-component array operations (@code{and}, @code{or},
16751@code{xor}, @code{not}, and relational tests other than equality)
16752are not implemented.
16753
16754@item
860701dc
PH
16755@cindex array aggregates (Ada)
16756@cindex record aggregates (Ada)
16757@cindex aggregates (Ada)
16758There is limited support for array and record aggregates. They are
16759permitted only on the right sides of assignments, as in these examples:
16760
16761@smallexample
077e0a52
JB
16762(@value{GDBP}) set An_Array := (1, 2, 3, 4, 5, 6)
16763(@value{GDBP}) set An_Array := (1, others => 0)
16764(@value{GDBP}) set An_Array := (0|4 => 1, 1..3 => 2, 5 => 6)
16765(@value{GDBP}) set A_2D_Array := ((1, 2, 3), (4, 5, 6), (7, 8, 9))
16766(@value{GDBP}) set A_Record := (1, "Peter", True);
16767(@value{GDBP}) set A_Record := (Name => "Peter", Id => 1, Alive => True)
860701dc
PH
16768@end smallexample
16769
16770Changing a
16771discriminant's value by assigning an aggregate has an
16772undefined effect if that discriminant is used within the record.
16773However, you can first modify discriminants by directly assigning to
16774them (which normally would not be allowed in Ada), and then performing an
16775aggregate assignment. For example, given a variable @code{A_Rec}
16776declared to have a type such as:
16777
16778@smallexample
16779type Rec (Len : Small_Integer := 0) is record
16780 Id : Integer;
16781 Vals : IntArray (1 .. Len);
16782end record;
16783@end smallexample
16784
16785you can assign a value with a different size of @code{Vals} with two
16786assignments:
16787
16788@smallexample
077e0a52
JB
16789(@value{GDBP}) set A_Rec.Len := 4
16790(@value{GDBP}) set A_Rec := (Id => 42, Vals => (1, 2, 3, 4))
860701dc
PH
16791@end smallexample
16792
16793As this example also illustrates, @value{GDBN} is very loose about the usual
16794rules concerning aggregates. You may leave out some of the
16795components of an array or record aggregate (such as the @code{Len}
16796component in the assignment to @code{A_Rec} above); they will retain their
16797original values upon assignment. You may freely use dynamic values as
16798indices in component associations. You may even use overlapping or
16799redundant component associations, although which component values are
16800assigned in such cases is not defined.
e07c999f
PH
16801
16802@item
16803Calls to dispatching subprograms are not implemented.
16804
16805@item
16806The overloading algorithm is much more limited (i.e., less selective)
ae21e955
BW
16807than that of real Ada. It makes only limited use of the context in
16808which a subexpression appears to resolve its meaning, and it is much
16809looser in its rules for allowing type matches. As a result, some
16810function calls will be ambiguous, and the user will be asked to choose
16811the proper resolution.
e07c999f
PH
16812
16813@item
16814The @code{new} operator is not implemented.
16815
16816@item
16817Entry calls are not implemented.
16818
16819@item
16820Aside from printing, arithmetic operations on the native VAX floating-point
16821formats are not supported.
16822
16823@item
16824It is not possible to slice a packed array.
158c7665
PH
16825
16826@item
16827The names @code{True} and @code{False}, when not part of a qualified name,
16828are interpreted as if implicitly prefixed by @code{Standard}, regardless of
16829context.
16830Should your program
16831redefine these names in a package or procedure (at best a dubious practice),
16832you will have to use fully qualified names to access their new definitions.
e07c999f
PH
16833@end itemize
16834
16835@node Additions to Ada
16836@subsubsection Additions to Ada
16837@cindex Ada, deviations from
16838
16839As it does for other languages, @value{GDBN} makes certain generic
16840extensions to Ada (@pxref{Expressions}):
16841
16842@itemize @bullet
16843@item
ae21e955
BW
16844If the expression @var{E} is a variable residing in memory (typically
16845a local variable or array element) and @var{N} is a positive integer,
16846then @code{@var{E}@@@var{N}} displays the values of @var{E} and the
16847@var{N}-1 adjacent variables following it in memory as an array. In
16848Ada, this operator is generally not necessary, since its prime use is
16849in displaying parts of an array, and slicing will usually do this in
16850Ada. However, there are occasional uses when debugging programs in
16851which certain debugging information has been optimized away.
e07c999f
PH
16852
16853@item
ae21e955
BW
16854@code{@var{B}::@var{var}} means ``the variable named @var{var} that
16855appears in function or file @var{B}.'' When @var{B} is a file name,
16856you must typically surround it in single quotes.
e07c999f
PH
16857
16858@item
16859The expression @code{@{@var{type}@} @var{addr}} means ``the variable of type
16860@var{type} that appears at address @var{addr}.''
16861
16862@item
16863A name starting with @samp{$} is a convenience variable
16864(@pxref{Convenience Vars}) or a machine register (@pxref{Registers}).
16865@end itemize
16866
ae21e955
BW
16867In addition, @value{GDBN} provides a few other shortcuts and outright
16868additions specific to Ada:
e07c999f
PH
16869
16870@itemize @bullet
16871@item
16872The assignment statement is allowed as an expression, returning
16873its right-hand operand as its value. Thus, you may enter
16874
16875@smallexample
077e0a52
JB
16876(@value{GDBP}) set x := y + 3
16877(@value{GDBP}) print A(tmp := y + 1)
e07c999f
PH
16878@end smallexample
16879
16880@item
16881The semicolon is allowed as an ``operator,'' returning as its value
16882the value of its right-hand operand.
16883This allows, for example,
16884complex conditional breaks:
16885
16886@smallexample
077e0a52
JB
16887(@value{GDBP}) break f
16888(@value{GDBP}) condition 1 (report(i); k += 1; A(k) > 100)
e07c999f
PH
16889@end smallexample
16890
16891@item
16892Rather than use catenation and symbolic character names to introduce special
16893characters into strings, one may instead use a special bracket notation,
16894which is also used to print strings. A sequence of characters of the form
16895@samp{["@var{XX}"]} within a string or character literal denotes the
16896(single) character whose numeric encoding is @var{XX} in hexadecimal. The
16897sequence of characters @samp{["""]} also denotes a single quotation mark
16898in strings. For example,
16899@smallexample
16900 "One line.["0a"]Next line.["0a"]"
16901@end smallexample
16902@noindent
ae21e955
BW
16903contains an ASCII newline character (@code{Ada.Characters.Latin_1.LF})
16904after each period.
e07c999f
PH
16905
16906@item
16907The subtype used as a prefix for the attributes @t{'Pos}, @t{'Min}, and
16908@t{'Max} is optional (and is ignored in any case). For example, it is valid
16909to write
16910
16911@smallexample
077e0a52 16912(@value{GDBP}) print 'max(x, y)
e07c999f
PH
16913@end smallexample
16914
16915@item
16916When printing arrays, @value{GDBN} uses positional notation when the
16917array has a lower bound of 1, and uses a modified named notation otherwise.
ae21e955
BW
16918For example, a one-dimensional array of three integers with a lower bound
16919of 3 might print as
e07c999f
PH
16920
16921@smallexample
16922(3 => 10, 17, 1)
16923@end smallexample
16924
16925@noindent
16926That is, in contrast to valid Ada, only the first component has a @code{=>}
16927clause.
16928
16929@item
16930You may abbreviate attributes in expressions with any unique,
16931multi-character subsequence of
16932their names (an exact match gets preference).
16933For example, you may use @t{a'len}, @t{a'gth}, or @t{a'lh}
16934in place of @t{a'length}.
16935
16936@item
16937@cindex quoting Ada internal identifiers
16938Since Ada is case-insensitive, the debugger normally maps identifiers you type
16939to lower case. The GNAT compiler uses upper-case characters for
16940some of its internal identifiers, which are normally of no interest to users.
16941For the rare occasions when you actually have to look at them,
16942enclose them in angle brackets to avoid the lower-case mapping.
16943For example,
16944@smallexample
077e0a52 16945(@value{GDBP}) print <JMPBUF_SAVE>[0]
e07c999f
PH
16946@end smallexample
16947
16948@item
16949Printing an object of class-wide type or dereferencing an
16950access-to-class-wide value will display all the components of the object's
16951specific type (as indicated by its run-time tag). Likewise, component
16952selection on such a value will operate on the specific type of the
16953object.
16954
16955@end itemize
16956
3685b09f
PMR
16957@node Overloading support for Ada
16958@subsubsection Overloading support for Ada
16959@cindex overloading, Ada
16960
16961The debugger supports limited overloading. Given a subprogram call in which
16962the function symbol has multiple definitions, it will use the number of
16963actual parameters and some information about their types to attempt to narrow
16964the set of definitions. It also makes very limited use of context, preferring
16965procedures to functions in the context of the @code{call} command, and
16966functions to procedures elsewhere.
16967
16968If, after narrowing, the set of matching definitions still contains more than
16969one definition, @value{GDBN} will display a menu to query which one it should
16970use, for instance:
16971
16972@smallexample
16973(@value{GDBP}) print f(1)
16974Multiple matches for f
16975[0] cancel
16976[1] foo.f (integer) return boolean at foo.adb:23
16977[2] foo.f (foo.new_integer) return boolean at foo.adb:28
16978>
16979@end smallexample
16980
16981In this case, just select one menu entry either to cancel expression evaluation
16982(type @kbd{0} and press @key{RET}) or to continue evaluation with a specific
16983instance (type the corresponding number and press @key{RET}).
16984
16985Here are a couple of commands to customize @value{GDBN}'s behavior in this
16986case:
16987
16988@table @code
16989
16990@kindex set ada print-signatures
16991@item set ada print-signatures
16992Control whether parameter types and return types are displayed in overloads
16993selection menus. It is @code{on} by default.
16994@xref{Overloading support for Ada}.
16995
16996@kindex show ada print-signatures
16997@item show ada print-signatures
16998Show the current setting for displaying parameter types and return types in
16999overloads selection menu.
17000@xref{Overloading support for Ada}.
17001
17002@end table
17003
e07c999f
PH
17004@node Stopping Before Main Program
17005@subsubsection Stopping at the Very Beginning
17006
17007@cindex breakpointing Ada elaboration code
17008It is sometimes necessary to debug the program during elaboration, and
17009before reaching the main procedure.
17010As defined in the Ada Reference
17011Manual, the elaboration code is invoked from a procedure called
17012@code{adainit}. To run your program up to the beginning of
17013elaboration, simply use the following two commands:
17014@code{tbreak adainit} and @code{run}.
17015
58d06528
JB
17016@node Ada Exceptions
17017@subsubsection Ada Exceptions
17018
17019A command is provided to list all Ada exceptions:
17020
17021@table @code
17022@kindex info exceptions
17023@item info exceptions
17024@itemx info exceptions @var{regexp}
17025The @code{info exceptions} command allows you to list all Ada exceptions
17026defined within the program being debugged, as well as their addresses.
17027With a regular expression, @var{regexp}, as argument, only those exceptions
17028whose names match @var{regexp} are listed.
17029@end table
17030
17031Below is a small example, showing how the command can be used, first
17032without argument, and next with a regular expression passed as an
17033argument.
17034
17035@smallexample
17036(@value{GDBP}) info exceptions
17037All defined Ada exceptions:
17038constraint_error: 0x613da0
17039program_error: 0x613d20
17040storage_error: 0x613ce0
17041tasking_error: 0x613ca0
17042const.aint_global_e: 0x613b00
17043(@value{GDBP}) info exceptions const.aint
17044All Ada exceptions matching regular expression "const.aint":
17045constraint_error: 0x613da0
17046const.aint_global_e: 0x613b00
17047@end smallexample
17048
17049It is also possible to ask @value{GDBN} to stop your program's execution
17050when an exception is raised. For more details, see @ref{Set Catchpoints}.
17051
20924a55
JB
17052@node Ada Tasks
17053@subsubsection Extensions for Ada Tasks
17054@cindex Ada, tasking
17055
17056Support for Ada tasks is analogous to that for threads (@pxref{Threads}).
17057@value{GDBN} provides the following task-related commands:
17058
17059@table @code
17060@kindex info tasks
17061@item info tasks
17062This command shows a list of current Ada tasks, as in the following example:
17063
17064
17065@smallexample
17066@iftex
17067@leftskip=0.5cm
17068@end iftex
17069(@value{GDBP}) info tasks
17070 ID TID P-ID Pri State Name
17071 1 8088000 0 15 Child Activation Wait main_task
17072 2 80a4000 1 15 Accept Statement b
17073 3 809a800 1 15 Child Activation Wait a
32cd1edc 17074* 4 80ae800 3 15 Runnable c
20924a55
JB
17075
17076@end smallexample
17077
17078@noindent
17079In this listing, the asterisk before the last task indicates it to be the
17080task currently being inspected.
17081
17082@table @asis
17083@item ID
17084Represents @value{GDBN}'s internal task number.
17085
17086@item TID
17087The Ada task ID.
17088
17089@item P-ID
17090The parent's task ID (@value{GDBN}'s internal task number).
17091
17092@item Pri
17093The base priority of the task.
17094
17095@item State
17096Current state of the task.
17097
17098@table @code
17099@item Unactivated
17100The task has been created but has not been activated. It cannot be
17101executing.
17102
20924a55
JB
17103@item Runnable
17104The task is not blocked for any reason known to Ada. (It may be waiting
17105for a mutex, though.) It is conceptually "executing" in normal mode.
17106
17107@item Terminated
17108The task is terminated, in the sense of ARM 9.3 (5). Any dependents
17109that were waiting on terminate alternatives have been awakened and have
17110terminated themselves.
17111
17112@item Child Activation Wait
17113The task is waiting for created tasks to complete activation.
17114
17115@item Accept Statement
17116The task is waiting on an accept or selective wait statement.
17117
17118@item Waiting on entry call
17119The task is waiting on an entry call.
17120
17121@item Async Select Wait
17122The task is waiting to start the abortable part of an asynchronous
17123select statement.
17124
17125@item Delay Sleep
17126The task is waiting on a select statement with only a delay
17127alternative open.
17128
17129@item Child Termination Wait
17130The task is sleeping having completed a master within itself, and is
17131waiting for the tasks dependent on that master to become terminated or
17132waiting on a terminate Phase.
17133
17134@item Wait Child in Term Alt
17135The task is sleeping waiting for tasks on terminate alternatives to
17136finish terminating.
17137
17138@item Accepting RV with @var{taskno}
17139The task is accepting a rendez-vous with the task @var{taskno}.
17140@end table
17141
17142@item Name
17143Name of the task in the program.
17144
17145@end table
17146
17147@kindex info task @var{taskno}
17148@item info task @var{taskno}
17149This command shows detailled informations on the specified task, as in
17150the following example:
17151@smallexample
17152@iftex
17153@leftskip=0.5cm
17154@end iftex
17155(@value{GDBP}) info tasks
17156 ID TID P-ID Pri State Name
17157 1 8077880 0 15 Child Activation Wait main_task
32cd1edc 17158* 2 807c468 1 15 Runnable task_1
20924a55
JB
17159(@value{GDBP}) info task 2
17160Ada Task: 0x807c468
17161Name: task_1
87f7ab7b
JB
17162Thread: 0
17163LWP: 0x1fac
20924a55
JB
17164Parent: 1 (main_task)
17165Base Priority: 15
17166State: Runnable
17167@end smallexample
17168
17169@item task
17170@kindex task@r{ (Ada)}
17171@cindex current Ada task ID
17172This command prints the ID of the current task.
17173
17174@smallexample
17175@iftex
17176@leftskip=0.5cm
17177@end iftex
17178(@value{GDBP}) info tasks
17179 ID TID P-ID Pri State Name
17180 1 8077870 0 15 Child Activation Wait main_task
32cd1edc 17181* 2 807c458 1 15 Runnable t
20924a55
JB
17182(@value{GDBP}) task
17183[Current task is 2]
17184@end smallexample
17185
17186@item task @var{taskno}
17187@cindex Ada task switching
5d5658a1 17188This command is like the @code{thread @var{thread-id}}
20924a55
JB
17189command (@pxref{Threads}). It switches the context of debugging
17190from the current task to the given task.
17191
17192@smallexample
17193@iftex
17194@leftskip=0.5cm
17195@end iftex
17196(@value{GDBP}) info tasks
17197 ID TID P-ID Pri State Name
17198 1 8077870 0 15 Child Activation Wait main_task
32cd1edc 17199* 2 807c458 1 15 Runnable t
20924a55
JB
17200(@value{GDBP}) task 1
17201[Switching to task 1]
17202#0 0x8067726 in pthread_cond_wait ()
17203(@value{GDBP}) bt
17204#0 0x8067726 in pthread_cond_wait ()
17205#1 0x8056714 in system.os_interface.pthread_cond_wait ()
17206#2 0x805cb63 in system.task_primitives.operations.sleep ()
17207#3 0x806153e in system.tasking.stages.activate_tasks ()
17208#4 0x804aacc in un () at un.adb:5
17209@end smallexample
17210
629500fa
KS
17211@item break @var{location} task @var{taskno}
17212@itemx break @var{location} task @var{taskno} if @dots{}
45ac276d
JB
17213@cindex breakpoints and tasks, in Ada
17214@cindex task breakpoints, in Ada
17215@kindex break @dots{} task @var{taskno}@r{ (Ada)}
17216These commands are like the @code{break @dots{} thread @dots{}}
697aa1b7 17217command (@pxref{Thread Stops}). The
629500fa 17218@var{location} argument specifies source lines, as described
45ac276d
JB
17219in @ref{Specify Location}.
17220
17221Use the qualifier @samp{task @var{taskno}} with a breakpoint command
17222to specify that you only want @value{GDBN} to stop the program when a
697aa1b7 17223particular Ada task reaches this breakpoint. The @var{taskno} is one of the
45ac276d
JB
17224numeric task identifiers assigned by @value{GDBN}, shown in the first
17225column of the @samp{info tasks} display.
17226
17227If you do not specify @samp{task @var{taskno}} when you set a
17228breakpoint, the breakpoint applies to @emph{all} tasks of your
17229program.
17230
17231You can use the @code{task} qualifier on conditional breakpoints as
17232well; in this case, place @samp{task @var{taskno}} before the
17233breakpoint condition (before the @code{if}).
17234
17235For example,
17236
17237@smallexample
17238@iftex
17239@leftskip=0.5cm
17240@end iftex
17241(@value{GDBP}) info tasks
17242 ID TID P-ID Pri State Name
17243 1 140022020 0 15 Child Activation Wait main_task
17244 2 140045060 1 15 Accept/Select Wait t2
17245 3 140044840 1 15 Runnable t1
17246* 4 140056040 1 15 Runnable t3
17247(@value{GDBP}) b 15 task 2
17248Breakpoint 5 at 0x120044cb0: file test_task_debug.adb, line 15.
17249(@value{GDBP}) cont
17250Continuing.
17251task # 1 running
17252task # 2 running
17253
17254Breakpoint 5, test_task_debug () at test_task_debug.adb:15
1725515 flush;
17256(@value{GDBP}) info tasks
17257 ID TID P-ID Pri State Name
17258 1 140022020 0 15 Child Activation Wait main_task
17259* 2 140045060 1 15 Runnable t2
17260 3 140044840 1 15 Runnable t1
17261 4 140056040 1 15 Delay Sleep t3
17262@end smallexample
20924a55
JB
17263@end table
17264
17265@node Ada Tasks and Core Files
17266@subsubsection Tasking Support when Debugging Core Files
17267@cindex Ada tasking and core file debugging
17268
17269When inspecting a core file, as opposed to debugging a live program,
17270tasking support may be limited or even unavailable, depending on
17271the platform being used.
17272For instance, on x86-linux, the list of tasks is available, but task
32a8097b 17273switching is not supported.
20924a55 17274
32a8097b 17275On certain platforms, the debugger needs to perform some
20924a55
JB
17276memory writes in order to provide Ada tasking support. When inspecting
17277a core file, this means that the core file must be opened with read-write
17278privileges, using the command @samp{"set write on"} (@pxref{Patching}).
17279Under these circumstances, you should make a backup copy of the core
17280file before inspecting it with @value{GDBN}.
17281
6e1bb179
JB
17282@node Ravenscar Profile
17283@subsubsection Tasking Support when using the Ravenscar Profile
17284@cindex Ravenscar Profile
17285
17286The @dfn{Ravenscar Profile} is a subset of the Ada tasking features,
17287specifically designed for systems with safety-critical real-time
17288requirements.
17289
17290@table @code
17291@kindex set ravenscar task-switching on
17292@cindex task switching with program using Ravenscar Profile
17293@item set ravenscar task-switching on
17294Allows task switching when debugging a program that uses the Ravenscar
17295Profile. This is the default.
17296
17297@kindex set ravenscar task-switching off
17298@item set ravenscar task-switching off
17299Turn off task switching when debugging a program that uses the Ravenscar
17300Profile. This is mostly intended to disable the code that adds support
17301for the Ravenscar Profile, in case a bug in either @value{GDBN} or in
17302the Ravenscar runtime is preventing @value{GDBN} from working properly.
17303To be effective, this command should be run before the program is started.
17304
17305@kindex show ravenscar task-switching
17306@item show ravenscar task-switching
17307Show whether it is possible to switch from task to task in a program
17308using the Ravenscar Profile.
17309
17310@end table
17311
3fcded8f
JB
17312@node Ada Settings
17313@subsubsection Ada Settings
17314@cindex Ada settings
17315
17316@table @code
17317@kindex set varsize-limit
17318@item set varsize-limit @var{size}
17319Prevent @value{GDBN} from attempting to evaluate objects whose size
17320is above the given limit (@var{size}) when those sizes are computed
17321from run-time quantities. This is typically the case when the object
17322has a variable size, such as an array whose bounds are not known at
17323compile time for example. Setting @var{size} to @code{unlimited}
17324removes the size limitation. By default, the limit is about 65KB.
17325
17326The purpose of having such a limit is to prevent @value{GDBN} from
17327trying to grab enormous chunks of virtual memory when asked to evaluate
17328a quantity whose bounds have been corrupted or have not yet been fully
17329initialized. The limit applies to the results of some subexpressions
17330as well as to complete expressions. For example, an expression denoting
17331a simple integer component, such as @code{x.y.z}, may fail if the size of
17332@code{x.y} is variable and exceeds @code{size}. On the other hand,
17333@value{GDBN} is sometimes clever; the expression @code{A(i)}, where
17334@code{A} is an array variable with non-constant size, will generally
17335succeed regardless of the bounds on @code{A}, as long as the component
17336size is less than @var{size}.
17337
17338@kindex show varsize-limit
17339@item show varsize-limit
17340Show the limit on types whose size is determined by run-time quantities.
17341@end table
17342
e07c999f
PH
17343@node Ada Glitches
17344@subsubsection Known Peculiarities of Ada Mode
17345@cindex Ada, problems
17346
17347Besides the omissions listed previously (@pxref{Omissions from Ada}),
17348we know of several problems with and limitations of Ada mode in
17349@value{GDBN},
17350some of which will be fixed with planned future releases of the debugger
17351and the GNU Ada compiler.
17352
17353@itemize @bullet
e07c999f
PH
17354@item
17355Static constants that the compiler chooses not to materialize as objects in
17356storage are invisible to the debugger.
17357
17358@item
17359Named parameter associations in function argument lists are ignored (the
17360argument lists are treated as positional).
17361
17362@item
17363Many useful library packages are currently invisible to the debugger.
17364
17365@item
17366Fixed-point arithmetic, conversions, input, and output is carried out using
17367floating-point arithmetic, and may give results that only approximate those on
17368the host machine.
17369
e07c999f
PH
17370@item
17371The GNAT compiler never generates the prefix @code{Standard} for any of
17372the standard symbols defined by the Ada language. @value{GDBN} knows about
17373this: it will strip the prefix from names when you use it, and will never
17374look for a name you have so qualified among local symbols, nor match against
17375symbols in other packages or subprograms. If you have
17376defined entities anywhere in your program other than parameters and
17377local variables whose simple names match names in @code{Standard},
17378GNAT's lack of qualification here can cause confusion. When this happens,
17379you can usually resolve the confusion
17380by qualifying the problematic names with package
17381@code{Standard} explicitly.
17382@end itemize
17383
95433b34
JB
17384Older versions of the compiler sometimes generate erroneous debugging
17385information, resulting in the debugger incorrectly printing the value
17386of affected entities. In some cases, the debugger is able to work
17387around an issue automatically. In other cases, the debugger is able
17388to work around the issue, but the work-around has to be specifically
17389enabled.
17390
17391@kindex set ada trust-PAD-over-XVS
17392@kindex show ada trust-PAD-over-XVS
17393@table @code
17394
17395@item set ada trust-PAD-over-XVS on
17396Configure GDB to strictly follow the GNAT encoding when computing the
17397value of Ada entities, particularly when @code{PAD} and @code{PAD___XVS}
17398types are involved (see @code{ada/exp_dbug.ads} in the GCC sources for
17399a complete description of the encoding used by the GNAT compiler).
17400This is the default.
17401
17402@item set ada trust-PAD-over-XVS off
17403This is related to the encoding using by the GNAT compiler. If @value{GDBN}
17404sometimes prints the wrong value for certain entities, changing @code{ada
17405trust-PAD-over-XVS} to @code{off} activates a work-around which may fix
17406the issue. It is always safe to set @code{ada trust-PAD-over-XVS} to
17407@code{off}, but this incurs a slight performance penalty, so it is
17408recommended to leave this setting to @code{on} unless necessary.
17409
17410@end table
17411
c6044dd1
JB
17412@cindex GNAT descriptive types
17413@cindex GNAT encoding
17414Internally, the debugger also relies on the compiler following a number
17415of conventions known as the @samp{GNAT Encoding}, all documented in
17416@file{gcc/ada/exp_dbug.ads} in the GCC sources. This encoding describes
17417how the debugging information should be generated for certain types.
17418In particular, this convention makes use of @dfn{descriptive types},
17419which are artificial types generated purely to help the debugger.
17420
17421These encodings were defined at a time when the debugging information
17422format used was not powerful enough to describe some of the more complex
17423types available in Ada. Since DWARF allows us to express nearly all
17424Ada features, the long-term goal is to slowly replace these descriptive
17425types by their pure DWARF equivalent. To facilitate that transition,
17426a new maintenance option is available to force the debugger to ignore
17427those descriptive types. It allows the user to quickly evaluate how
17428well @value{GDBN} works without them.
17429
17430@table @code
17431
17432@kindex maint ada set ignore-descriptive-types
17433@item maintenance ada set ignore-descriptive-types [on|off]
17434Control whether the debugger should ignore descriptive types.
17435The default is not to ignore descriptives types (@code{off}).
17436
17437@kindex maint ada show ignore-descriptive-types
17438@item maintenance ada show ignore-descriptive-types
17439Show if descriptive types are ignored by @value{GDBN}.
17440
17441@end table
17442
79a6e687
BW
17443@node Unsupported Languages
17444@section Unsupported Languages
4e562065
JB
17445
17446@cindex unsupported languages
17447@cindex minimal language
17448In addition to the other fully-supported programming languages,
17449@value{GDBN} also provides a pseudo-language, called @code{minimal}.
17450It does not represent a real programming language, but provides a set
17451of capabilities close to what the C or assembly languages provide.
17452This should allow most simple operations to be performed while debugging
17453an application that uses a language currently not supported by @value{GDBN}.
17454
17455If the language is set to @code{auto}, @value{GDBN} will automatically
17456select this language if the current frame corresponds to an unsupported
17457language.
17458
6d2ebf8b 17459@node Symbols
c906108c
SS
17460@chapter Examining the Symbol Table
17461
d4f3574e 17462The commands described in this chapter allow you to inquire about the
c906108c
SS
17463symbols (names of variables, functions and types) defined in your
17464program. This information is inherent in the text of your program and
17465does not change as your program executes. @value{GDBN} finds it in your
17466program's symbol table, in the file indicated when you started @value{GDBN}
79a6e687
BW
17467(@pxref{File Options, ,Choosing Files}), or by one of the
17468file-management commands (@pxref{Files, ,Commands to Specify Files}).
c906108c
SS
17469
17470@cindex symbol names
17471@cindex names of symbols
17472@cindex quoting names
d044bac8 17473@anchor{quoting names}
c906108c
SS
17474Occasionally, you may need to refer to symbols that contain unusual
17475characters, which @value{GDBN} ordinarily treats as word delimiters. The
17476most frequent case is in referring to static variables in other
79a6e687 17477source files (@pxref{Variables,,Program Variables}). File names
c906108c
SS
17478are recorded in object files as debugging symbols, but @value{GDBN} would
17479ordinarily parse a typical file name, like @file{foo.c}, as the three words
17480@samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize
17481@samp{foo.c} as a single symbol, enclose it in single quotes; for example,
17482
474c8240 17483@smallexample
c906108c 17484p 'foo.c'::x
474c8240 17485@end smallexample
c906108c
SS
17486
17487@noindent
17488looks up the value of @code{x} in the scope of the file @file{foo.c}.
17489
17490@table @code
a8f24a35
EZ
17491@cindex case-insensitive symbol names
17492@cindex case sensitivity in symbol names
17493@kindex set case-sensitive
17494@item set case-sensitive on
17495@itemx set case-sensitive off
17496@itemx set case-sensitive auto
17497Normally, when @value{GDBN} looks up symbols, it matches their names
17498with case sensitivity determined by the current source language.
17499Occasionally, you may wish to control that. The command @code{set
17500case-sensitive} lets you do that by specifying @code{on} for
17501case-sensitive matches or @code{off} for case-insensitive ones. If
17502you specify @code{auto}, case sensitivity is reset to the default
17503suitable for the source language. The default is case-sensitive
17504matches for all languages except for Fortran, for which the default is
17505case-insensitive matches.
17506
9c16f35a
EZ
17507@kindex show case-sensitive
17508@item show case-sensitive
a8f24a35
EZ
17509This command shows the current setting of case sensitivity for symbols
17510lookups.
17511
53342f27
TT
17512@kindex set print type methods
17513@item set print type methods
17514@itemx set print type methods on
17515@itemx set print type methods off
17516Normally, when @value{GDBN} prints a class, it displays any methods
17517declared in that class. You can control this behavior either by
17518passing the appropriate flag to @code{ptype}, or using @command{set
17519print type methods}. Specifying @code{on} will cause @value{GDBN} to
17520display the methods; this is the default. Specifying @code{off} will
17521cause @value{GDBN} to omit the methods.
17522
17523@kindex show print type methods
17524@item show print type methods
17525This command shows the current setting of method display when printing
17526classes.
17527
883fd55a
KS
17528@kindex set print type nested-type-limit
17529@item set print type nested-type-limit @var{limit}
17530@itemx set print type nested-type-limit unlimited
17531Set the limit of displayed nested types that the type printer will
17532show. A @var{limit} of @code{unlimited} or @code{-1} will show all
17533nested definitions. By default, the type printer will not show any nested
17534types defined in classes.
17535
17536@kindex show print type nested-type-limit
17537@item show print type nested-type-limit
17538This command shows the current display limit of nested types when
17539printing classes.
17540
53342f27
TT
17541@kindex set print type typedefs
17542@item set print type typedefs
17543@itemx set print type typedefs on
17544@itemx set print type typedefs off
17545
17546Normally, when @value{GDBN} prints a class, it displays any typedefs
17547defined in that class. You can control this behavior either by
17548passing the appropriate flag to @code{ptype}, or using @command{set
17549print type typedefs}. Specifying @code{on} will cause @value{GDBN} to
17550display the typedef definitions; this is the default. Specifying
17551@code{off} will cause @value{GDBN} to omit the typedef definitions.
17552Note that this controls whether the typedef definition itself is
17553printed, not whether typedef names are substituted when printing other
17554types.
17555
17556@kindex show print type typedefs
17557@item show print type typedefs
17558This command shows the current setting of typedef display when
17559printing classes.
17560
c906108c 17561@kindex info address
b37052ae 17562@cindex address of a symbol
c906108c
SS
17563@item info address @var{symbol}
17564Describe where the data for @var{symbol} is stored. For a register
17565variable, this says which register it is kept in. For a non-register
17566local variable, this prints the stack-frame offset at which the variable
17567is always stored.
17568
17569Note the contrast with @samp{print &@var{symbol}}, which does not work
17570at all for a register variable, and for a stack local variable prints
17571the exact address of the current instantiation of the variable.
17572
3d67e040 17573@kindex info symbol
b37052ae 17574@cindex symbol from address
9c16f35a 17575@cindex closest symbol and offset for an address
3d67e040
EZ
17576@item info symbol @var{addr}
17577Print the name of a symbol which is stored at the address @var{addr}.
17578If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the
17579nearest symbol and an offset from it:
17580
474c8240 17581@smallexample
3d67e040
EZ
17582(@value{GDBP}) info symbol 0x54320
17583_initialize_vx + 396 in section .text
474c8240 17584@end smallexample
3d67e040
EZ
17585
17586@noindent
17587This is the opposite of the @code{info address} command. You can use
17588it to find out the name of a variable or a function given its address.
17589
c14c28ba
PP
17590For dynamically linked executables, the name of executable or shared
17591library containing the symbol is also printed:
17592
17593@smallexample
17594(@value{GDBP}) info symbol 0x400225
17595_start + 5 in section .text of /tmp/a.out
17596(@value{GDBP}) info symbol 0x2aaaac2811cf
17597__read_nocancel + 6 in section .text of /usr/lib64/libc.so.6
17598@end smallexample
17599
439250fb
DE
17600@kindex demangle
17601@cindex demangle
17602@item demangle @r{[}-l @var{language}@r{]} @r{[}@var{--}@r{]} @var{name}
17603Demangle @var{name}.
17604If @var{language} is provided it is the name of the language to demangle
17605@var{name} in. Otherwise @var{name} is demangled in the current language.
17606
17607The @samp{--} option specifies the end of options,
17608and is useful when @var{name} begins with a dash.
17609
17610The parameter @code{demangle-style} specifies how to interpret the kind
17611of mangling used. @xref{Print Settings}.
17612
c906108c 17613@kindex whatis
53342f27 17614@item whatis[/@var{flags}] [@var{arg}]
177bc839
JK
17615Print the data type of @var{arg}, which can be either an expression
17616or a name of a data type. With no argument, print the data type of
17617@code{$}, the last value in the value history.
17618
17619If @var{arg} is an expression (@pxref{Expressions, ,Expressions}), it
17620is not actually evaluated, and any side-effecting operations (such as
17621assignments or function calls) inside it do not take place.
17622
17623If @var{arg} is a variable or an expression, @code{whatis} prints its
17624literal type as it is used in the source code. If the type was
17625defined using a @code{typedef}, @code{whatis} will @emph{not} print
17626the data type underlying the @code{typedef}. If the type of the
17627variable or the expression is a compound data type, such as
17628@code{struct} or @code{class}, @code{whatis} never prints their
17629fields or methods. It just prints the @code{struct}/@code{class}
17630name (a.k.a.@: its @dfn{tag}). If you want to see the members of
17631such a compound data type, use @code{ptype}.
17632
17633If @var{arg} is a type name that was defined using @code{typedef},
17634@code{whatis} @dfn{unrolls} only one level of that @code{typedef}.
17635Unrolling means that @code{whatis} will show the underlying type used
17636in the @code{typedef} declaration of @var{arg}. However, if that
17637underlying type is also a @code{typedef}, @code{whatis} will not
17638unroll it.
17639
17640For C code, the type names may also have the form @samp{class
17641@var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union
17642@var{union-tag}} or @samp{enum @var{enum-tag}}.
c906108c 17643
53342f27
TT
17644@var{flags} can be used to modify how the type is displayed.
17645Available flags are:
17646
17647@table @code
17648@item r
17649Display in ``raw'' form. Normally, @value{GDBN} substitutes template
17650parameters and typedefs defined in a class when printing the class'
17651members. The @code{/r} flag disables this.
17652
17653@item m
17654Do not print methods defined in the class.
17655
17656@item M
17657Print methods defined in the class. This is the default, but the flag
17658exists in case you change the default with @command{set print type methods}.
17659
17660@item t
17661Do not print typedefs defined in the class. Note that this controls
17662whether the typedef definition itself is printed, not whether typedef
17663names are substituted when printing other types.
17664
17665@item T
17666Print typedefs defined in the class. This is the default, but the flag
17667exists in case you change the default with @command{set print type typedefs}.
7c161838
SDJ
17668
17669@item o
17670Print the offsets and sizes of fields in a struct, similar to what the
17671@command{pahole} tool does. This option implies the @code{/tm} flags.
17672
17673For example, given the following declarations:
17674
17675@smallexample
17676struct tuv
17677@{
17678 int a1;
17679 char *a2;
17680 int a3;
17681@};
17682
17683struct xyz
17684@{
17685 int f1;
17686 char f2;
17687 void *f3;
17688 struct tuv f4;
17689@};
17690
17691union qwe
17692@{
17693 struct tuv fff1;
17694 struct xyz fff2;
17695@};
17696
17697struct tyu
17698@{
17699 int a1 : 1;
17700 int a2 : 3;
17701 int a3 : 23;
17702 char a4 : 2;
17703 int64_t a5;
17704 int a6 : 5;
17705 int64_t a7 : 3;
17706@};
17707@end smallexample
17708
17709Issuing a @kbd{ptype /o struct tuv} command would print:
17710
17711@smallexample
17712(@value{GDBP}) ptype /o struct tuv
17713/* offset | size */ type = struct tuv @{
17714/* 0 | 4 */ int a1;
17715/* XXX 4-byte hole */
17716/* 8 | 8 */ char *a2;
17717/* 16 | 4 */ int a3;
17718
17719 /* total size (bytes): 24 */
17720 @}
17721@end smallexample
17722
17723Notice the format of the first column of comments. There, you can
17724find two parts separated by the @samp{|} character: the @emph{offset},
17725which indicates where the field is located inside the struct, in
17726bytes, and the @emph{size} of the field. Another interesting line is
17727the marker of a @emph{hole} in the struct, indicating that it may be
17728possible to pack the struct and make it use less space by reorganizing
17729its fields.
17730
17731It is also possible to print offsets inside an union:
17732
17733@smallexample
17734(@value{GDBP}) ptype /o union qwe
17735/* offset | size */ type = union qwe @{
17736/* 24 */ struct tuv @{
17737/* 0 | 4 */ int a1;
17738/* XXX 4-byte hole */
17739/* 8 | 8 */ char *a2;
17740/* 16 | 4 */ int a3;
17741
17742 /* total size (bytes): 24 */
17743 @} fff1;
17744/* 40 */ struct xyz @{
17745/* 0 | 4 */ int f1;
17746/* 4 | 1 */ char f2;
17747/* XXX 3-byte hole */
17748/* 8 | 8 */ void *f3;
17749/* 16 | 24 */ struct tuv @{
17750/* 16 | 4 */ int a1;
17751/* XXX 4-byte hole */
17752/* 24 | 8 */ char *a2;
17753/* 32 | 4 */ int a3;
17754
17755 /* total size (bytes): 24 */
17756 @} f4;
17757
17758 /* total size (bytes): 40 */
17759 @} fff2;
17760
17761 /* total size (bytes): 40 */
17762 @}
17763@end smallexample
17764
17765In this case, since @code{struct tuv} and @code{struct xyz} occupy the
17766same space (because we are dealing with an union), the offset is not
17767printed for them. However, you can still examine the offset of each
17768of these structures' fields.
17769
17770Another useful scenario is printing the offsets of a struct containing
17771bitfields:
17772
17773@smallexample
17774(@value{GDBP}) ptype /o struct tyu
17775/* offset | size */ type = struct tyu @{
17776/* 0:31 | 4 */ int a1 : 1;
17777/* 0:28 | 4 */ int a2 : 3;
17778/* 0: 5 | 4 */ int a3 : 23;
17779/* 3: 3 | 1 */ signed char a4 : 2;
17780/* XXX 3-bit hole */
17781/* XXX 4-byte hole */
17782/* 8 | 8 */ int64_t a5;
17783/* 16:27 | 4 */ int a6 : 5;
17784/* 16:56 | 8 */ int64_t a7 : 3;
17785
17786 /* total size (bytes): 24 */
17787 @}
17788@end smallexample
17789
17790Note how the offset information is now extended to also include how
17791many bits are left to be used in each bitfield.
53342f27
TT
17792@end table
17793
c906108c 17794@kindex ptype
53342f27 17795@item ptype[/@var{flags}] [@var{arg}]
62f3a2ba
FF
17796@code{ptype} accepts the same arguments as @code{whatis}, but prints a
17797detailed description of the type, instead of just the name of the type.
17798@xref{Expressions, ,Expressions}.
c906108c 17799
177bc839
JK
17800Contrary to @code{whatis}, @code{ptype} always unrolls any
17801@code{typedef}s in its argument declaration, whether the argument is
17802a variable, expression, or a data type. This means that @code{ptype}
17803of a variable or an expression will not print literally its type as
17804present in the source code---use @code{whatis} for that. @code{typedef}s at
17805the pointer or reference targets are also unrolled. Only @code{typedef}s of
17806fields, methods and inner @code{class typedef}s of @code{struct}s,
17807@code{class}es and @code{union}s are not unrolled even with @code{ptype}.
17808
c906108c
SS
17809For example, for this variable declaration:
17810
474c8240 17811@smallexample
177bc839
JK
17812typedef double real_t;
17813struct complex @{ real_t real; double imag; @};
17814typedef struct complex complex_t;
17815complex_t var;
17816real_t *real_pointer_var;
474c8240 17817@end smallexample
c906108c
SS
17818
17819@noindent
17820the two commands give this output:
17821
474c8240 17822@smallexample
c906108c 17823@group
177bc839
JK
17824(@value{GDBP}) whatis var
17825type = complex_t
17826(@value{GDBP}) ptype var
17827type = struct complex @{
17828 real_t real;
17829 double imag;
17830@}
17831(@value{GDBP}) whatis complex_t
17832type = struct complex
17833(@value{GDBP}) whatis struct complex
c906108c 17834type = struct complex
177bc839 17835(@value{GDBP}) ptype struct complex
c906108c 17836type = struct complex @{
177bc839 17837 real_t real;
c906108c
SS
17838 double imag;
17839@}
177bc839
JK
17840(@value{GDBP}) whatis real_pointer_var
17841type = real_t *
17842(@value{GDBP}) ptype real_pointer_var
17843type = double *
c906108c 17844@end group
474c8240 17845@end smallexample
c906108c
SS
17846
17847@noindent
17848As with @code{whatis}, using @code{ptype} without an argument refers to
17849the type of @code{$}, the last value in the value history.
17850
ab1adacd
EZ
17851@cindex incomplete type
17852Sometimes, programs use opaque data types or incomplete specifications
17853of complex data structure. If the debug information included in the
17854program does not allow @value{GDBN} to display a full declaration of
17855the data type, it will say @samp{<incomplete type>}. For example,
17856given these declarations:
17857
17858@smallexample
17859 struct foo;
17860 struct foo *fooptr;
17861@end smallexample
17862
17863@noindent
17864but no definition for @code{struct foo} itself, @value{GDBN} will say:
17865
17866@smallexample
ddb50cd7 17867 (@value{GDBP}) ptype foo
ab1adacd
EZ
17868 $1 = <incomplete type>
17869@end smallexample
17870
17871@noindent
17872``Incomplete type'' is C terminology for data types that are not
17873completely specified.
17874
d69cf9b2
PA
17875@cindex unknown type
17876Othertimes, information about a variable's type is completely absent
17877from the debug information included in the program. This most often
17878happens when the program or library where the variable is defined
17879includes no debug information at all. @value{GDBN} knows the variable
17880exists from inspecting the linker/loader symbol table (e.g., the ELF
17881dynamic symbol table), but such symbols do not contain type
17882information. Inspecting the type of a (global) variable for which
17883@value{GDBN} has no type information shows:
17884
17885@smallexample
17886 (@value{GDBP}) ptype var
17887 type = <data variable, no debug info>
17888@end smallexample
17889
17890@xref{Variables, no debug info variables}, for how to print the values
17891of such variables.
17892
c906108c
SS
17893@kindex info types
17894@item info types @var{regexp}
17895@itemx info types
09d4efe1
EZ
17896Print a brief description of all types whose names match the regular
17897expression @var{regexp} (or all types in your program, if you supply
17898no argument). Each complete typename is matched as though it were a
17899complete line; thus, @samp{i type value} gives information on all
17900types in your program whose names include the string @code{value}, but
17901@samp{i type ^value$} gives information only on types whose complete
17902name is @code{value}.
c906108c 17903
20813a0b
PW
17904In programs using different languages, @value{GDBN} chooses the syntax
17905to print the type description according to the
17906@samp{set language} value: using @samp{set language auto}
17907(see @ref{Automatically, ,Set Language Automatically}) means to use the
17908language of the type, other values mean to use
17909the manually specified language (see @ref{Manually, ,Set Language Manually}).
17910
c906108c
SS
17911This command differs from @code{ptype} in two ways: first, like
17912@code{whatis}, it does not print a detailed description; second, it
b744723f 17913lists all source files and line numbers where a type is defined.
c906108c 17914
18a9fc12
TT
17915@kindex info type-printers
17916@item info type-printers
17917Versions of @value{GDBN} that ship with Python scripting enabled may
17918have ``type printers'' available. When using @command{ptype} or
17919@command{whatis}, these printers are consulted when the name of a type
17920is needed. @xref{Type Printing API}, for more information on writing
17921type printers.
17922
17923@code{info type-printers} displays all the available type printers.
17924
17925@kindex enable type-printer
17926@kindex disable type-printer
17927@item enable type-printer @var{name}@dots{}
17928@item disable type-printer @var{name}@dots{}
17929These commands can be used to enable or disable type printers.
17930
b37052ae
EZ
17931@kindex info scope
17932@cindex local variables
09d4efe1 17933@item info scope @var{location}
b37052ae 17934List all the variables local to a particular scope. This command
09d4efe1
EZ
17935accepts a @var{location} argument---a function name, a source line, or
17936an address preceded by a @samp{*}, and prints all the variables local
2a25a5ba
EZ
17937to the scope defined by that location. (@xref{Specify Location}, for
17938details about supported forms of @var{location}.) For example:
b37052ae
EZ
17939
17940@smallexample
17941(@value{GDBP}) @b{info scope command_line_handler}
17942Scope for command_line_handler:
17943Symbol rl is an argument at stack/frame offset 8, length 4.
17944Symbol linebuffer is in static storage at address 0x150a18, length 4.
17945Symbol linelength is in static storage at address 0x150a1c, length 4.
17946Symbol p is a local variable in register $esi, length 4.
17947Symbol p1 is a local variable in register $ebx, length 4.
17948Symbol nline is a local variable in register $edx, length 4.
17949Symbol repeat is a local variable at frame offset -8, length 4.
17950@end smallexample
17951
f5c37c66
EZ
17952@noindent
17953This command is especially useful for determining what data to collect
17954during a @dfn{trace experiment}, see @ref{Tracepoint Actions,
17955collect}.
17956
c906108c
SS
17957@kindex info source
17958@item info source
919d772c
JB
17959Show information about the current source file---that is, the source file for
17960the function containing the current point of execution:
17961@itemize @bullet
17962@item
17963the name of the source file, and the directory containing it,
17964@item
17965the directory it was compiled in,
17966@item
17967its length, in lines,
17968@item
17969which programming language it is written in,
17970@item
b6577aab
DE
17971if the debug information provides it, the program that compiled the file
17972(which may include, e.g., the compiler version and command line arguments),
17973@item
919d772c
JB
17974whether the executable includes debugging information for that file, and
17975if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and
17976@item
17977whether the debugging information includes information about
17978preprocessor macros.
17979@end itemize
17980
c906108c
SS
17981
17982@kindex info sources
17983@item info sources
17984Print the names of all source files in your program for which there is
17985debugging information, organized into two lists: files whose symbols
17986have already been read, and files whose symbols will be read when needed.
17987
17988@kindex info functions
d321477b 17989@item info functions [-q]
c906108c 17990Print the names and data types of all defined functions.
b744723f
AA
17991Similarly to @samp{info types}, this command groups its output by source
17992files and annotates each function definition with its source line
17993number.
c906108c 17994
20813a0b
PW
17995In programs using different languages, @value{GDBN} chooses the syntax
17996to print the function name and type according to the
17997@samp{set language} value: using @samp{set language auto}
17998(see @ref{Automatically, ,Set Language Automatically}) means to use the
17999language of the function, other values mean to use
18000the manually specified language (see @ref{Manually, ,Set Language Manually}).
18001
d321477b
PW
18002The optional flag @samp{-q}, which stands for @samp{quiet}, disables
18003printing header information and messages explaining why no functions
18004have been printed.
18005
18006@item info functions [-q] [-t @var{type_regexp}] [@var{regexp}]
18007Like @samp{info functions}, but only print the names and data types
18008of the functions selected with the provided regexp(s).
18009
18010If @var{regexp} is provided, print only the functions whose names
18011match the regular expression @var{regexp}.
18012Thus, @samp{info fun step} finds all functions whose
b744723f
AA
18013names include @code{step}; @samp{info fun ^step} finds those whose names
18014start with @code{step}. If a function name contains characters that
18015conflict with the regular expression language (e.g.@:
1c5dfdad 18016@samp{operator*()}), they may be quoted with a backslash.
c906108c 18017
d321477b
PW
18018If @var{type_regexp} is provided, print only the functions whose
18019types, as printed by the @code{whatis} command, match
18020the regular expression @var{type_regexp}.
18021If @var{type_regexp} contains space(s), it should be enclosed in
18022quote characters. If needed, use backslash to escape the meaning
18023of special characters or quotes.
18024Thus, @samp{info fun -t '^int ('} finds the functions that return
18025an integer; @samp{info fun -t '(.*int.*'} finds the functions that
18026have an argument type containing int; @samp{info fun -t '^int (' ^step}
18027finds the functions whose names start with @code{step} and that return
18028int.
18029
18030If both @var{regexp} and @var{type_regexp} are provided, a function
18031is printed only if its name matches @var{regexp} and its type matches
18032@var{type_regexp}.
18033
18034
c906108c 18035@kindex info variables
d321477b 18036@item info variables [-q]
0fe7935b 18037Print the names and data types of all variables that are defined
6ca652b0 18038outside of functions (i.e.@: excluding local variables).
b744723f
AA
18039The printed variables are grouped by source files and annotated with
18040their respective source line numbers.
c906108c 18041
20813a0b
PW
18042In programs using different languages, @value{GDBN} chooses the syntax
18043to print the variable name and type according to the
18044@samp{set language} value: using @samp{set language auto}
18045(see @ref{Automatically, ,Set Language Automatically}) means to use the
18046language of the variable, other values mean to use
18047the manually specified language (see @ref{Manually, ,Set Language Manually}).
18048
d321477b
PW
18049The optional flag @samp{-q}, which stands for @samp{quiet}, disables
18050printing header information and messages explaining why no variables
18051have been printed.
18052
18053@item info variables [-q] [-t @var{type_regexp}] [@var{regexp}]
18054Like @kbd{info variables}, but only print the variables selected
18055with the provided regexp(s).
18056
18057If @var{regexp} is provided, print only the variables whose names
18058match the regular expression @var{regexp}.
18059
18060If @var{type_regexp} is provided, print only the variables whose
18061types, as printed by the @code{whatis} command, match
18062the regular expression @var{type_regexp}.
18063If @var{type_regexp} contains space(s), it should be enclosed in
18064quote characters. If needed, use backslash to escape the meaning
18065of special characters or quotes.
18066
18067If both @var{regexp} and @var{type_regexp} are provided, an argument
18068is printed only if its name matches @var{regexp} and its type matches
18069@var{type_regexp}.
c906108c 18070
b37303ee 18071@kindex info classes
721c2651 18072@cindex Objective-C, classes and selectors
b37303ee
AF
18073@item info classes
18074@itemx info classes @var{regexp}
18075Display all Objective-C classes in your program, or
18076(with the @var{regexp} argument) all those matching a particular regular
18077expression.
18078
18079@kindex info selectors
18080@item info selectors
18081@itemx info selectors @var{regexp}
18082Display all Objective-C selectors in your program, or
18083(with the @var{regexp} argument) all those matching a particular regular
18084expression.
18085
c906108c
SS
18086@ignore
18087This was never implemented.
18088@kindex info methods
18089@item info methods
18090@itemx info methods @var{regexp}
18091The @code{info methods} command permits the user to examine all defined
b37052ae
EZ
18092methods within C@t{++} program, or (with the @var{regexp} argument) a
18093specific set of methods found in the various C@t{++} classes. Many
18094C@t{++} classes provide a large number of methods. Thus, the output
c906108c
SS
18095from the @code{ptype} command can be overwhelming and hard to use. The
18096@code{info-methods} command filters the methods, printing only those
18097which match the regular-expression @var{regexp}.
18098@end ignore
18099
9c16f35a 18100@cindex opaque data types
c906108c
SS
18101@kindex set opaque-type-resolution
18102@item set opaque-type-resolution on
18103Tell @value{GDBN} to resolve opaque types. An opaque type is a type
18104declared as a pointer to a @code{struct}, @code{class}, or
18105@code{union}---for example, @code{struct MyType *}---that is used in one
18106source file although the full declaration of @code{struct MyType} is in
18107another source file. The default is on.
18108
18109A change in the setting of this subcommand will not take effect until
18110the next time symbols for a file are loaded.
18111
18112@item set opaque-type-resolution off
18113Tell @value{GDBN} not to resolve opaque types. In this case, the type
18114is printed as follows:
18115@smallexample
18116@{<no data fields>@}
18117@end smallexample
18118
18119@kindex show opaque-type-resolution
18120@item show opaque-type-resolution
18121Show whether opaque types are resolved or not.
c906108c 18122
770e7fc7
DE
18123@kindex set print symbol-loading
18124@cindex print messages when symbols are loaded
18125@item set print symbol-loading
18126@itemx set print symbol-loading full
18127@itemx set print symbol-loading brief
18128@itemx set print symbol-loading off
18129The @code{set print symbol-loading} command allows you to control the
18130printing of messages when @value{GDBN} loads symbol information.
18131By default a message is printed for the executable and one for each
18132shared library, and normally this is what you want. However, when
18133debugging apps with large numbers of shared libraries these messages
18134can be annoying.
18135When set to @code{brief} a message is printed for each executable,
18136and when @value{GDBN} loads a collection of shared libraries at once
18137it will only print one message regardless of the number of shared
18138libraries. When set to @code{off} no messages are printed.
18139
18140@kindex show print symbol-loading
18141@item show print symbol-loading
18142Show whether messages will be printed when a @value{GDBN} command
18143entered from the keyboard causes symbol information to be loaded.
18144
c906108c
SS
18145@kindex maint print symbols
18146@cindex symbol dump
18147@kindex maint print psymbols
18148@cindex partial symbol dump
7c57fa1e
YQ
18149@kindex maint print msymbols
18150@cindex minimal symbol dump
34c41c68
DE
18151@item maint print symbols @r{[}-pc @var{address}@r{]} @r{[}@var{filename}@r{]}
18152@itemx maint print symbols @r{[}-objfile @var{objfile}@r{]} @r{[}-source @var{source}@r{]} @r{[}--@r{]} @r{[}@var{filename}@r{]}
18153@itemx maint print psymbols @r{[}-objfile @var{objfile}@r{]} @r{[}-pc @var{address}@r{]} @r{[}--@r{]} @r{[}@var{filename}@r{]}
18154@itemx maint print psymbols @r{[}-objfile @var{objfile}@r{]} @r{[}-source @var{source}@r{]} @r{[}--@r{]} @r{[}@var{filename}@r{]}
18155@itemx maint print msymbols @r{[}-objfile @var{objfile}@r{]} @r{[}--@r{]} @r{[}@var{filename}@r{]}
18156Write a dump of debugging symbol data into the file @var{filename} or
18157the terminal if @var{filename} is unspecified.
18158If @code{-objfile @var{objfile}} is specified, only dump symbols for
18159that objfile.
18160If @code{-pc @var{address}} is specified, only dump symbols for the file
18161with code at that address. Note that @var{address} may be a symbol like
18162@code{main}.
18163If @code{-source @var{source}} is specified, only dump symbols for that
18164source file.
18165
18166These commands are used to debug the @value{GDBN} symbol-reading code.
18167These commands do not modify internal @value{GDBN} state, therefore
18168@samp{maint print symbols} will only print symbols for already expanded symbol
18169tables.
18170You can use the command @code{info sources} to find out which files these are.
18171If you use @samp{maint print psymbols} instead, the dump shows information
18172about symbols that @value{GDBN} only knows partially---that is, symbols
18173defined in files that @value{GDBN} has skimmed, but not yet read completely.
18174Finally, @samp{maint print msymbols} just dumps ``minimal symbols'', e.g.,
18175``ELF symbols''.
18176
79a6e687 18177@xref{Files, ,Commands to Specify Files}, for a discussion of how
c906108c 18178@value{GDBN} reads symbols (in the description of @code{symbol-file}).
44ea7b70 18179
5e7b2f39
JB
18180@kindex maint info symtabs
18181@kindex maint info psymtabs
44ea7b70
JB
18182@cindex listing @value{GDBN}'s internal symbol tables
18183@cindex symbol tables, listing @value{GDBN}'s internal
18184@cindex full symbol tables, listing @value{GDBN}'s internal
18185@cindex partial symbol tables, listing @value{GDBN}'s internal
5e7b2f39
JB
18186@item maint info symtabs @r{[} @var{regexp} @r{]}
18187@itemx maint info psymtabs @r{[} @var{regexp} @r{]}
44ea7b70
JB
18188
18189List the @code{struct symtab} or @code{struct partial_symtab}
18190structures whose names match @var{regexp}. If @var{regexp} is not
18191given, list them all. The output includes expressions which you can
18192copy into a @value{GDBN} debugging this one to examine a particular
18193structure in more detail. For example:
18194
18195@smallexample
5e7b2f39 18196(@value{GDBP}) maint info psymtabs dwarf2read
44ea7b70
JB
18197@{ objfile /home/gnu/build/gdb/gdb
18198 ((struct objfile *) 0x82e69d0)
b383017d 18199 @{ psymtab /home/gnu/src/gdb/dwarf2read.c
44ea7b70
JB
18200 ((struct partial_symtab *) 0x8474b10)
18201 readin no
18202 fullname (null)
18203 text addresses 0x814d3c8 -- 0x8158074
18204 globals (* (struct partial_symbol **) 0x8507a08 @@ 9)
18205 statics (* (struct partial_symbol **) 0x40e95b78 @@ 2882)
18206 dependencies (none)
18207 @}
18208@}
5e7b2f39 18209(@value{GDBP}) maint info symtabs
44ea7b70
JB
18210(@value{GDBP})
18211@end smallexample
18212@noindent
18213We see that there is one partial symbol table whose filename contains
18214the string @samp{dwarf2read}, belonging to the @samp{gdb} executable;
18215and we see that @value{GDBN} has not read in any symtabs yet at all.
18216If we set a breakpoint on a function, that will cause @value{GDBN} to
18217read the symtab for the compilation unit containing that function:
18218
18219@smallexample
18220(@value{GDBP}) break dwarf2_psymtab_to_symtab
18221Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c,
18222line 1574.
5e7b2f39 18223(@value{GDBP}) maint info symtabs
b383017d 18224@{ objfile /home/gnu/build/gdb/gdb
44ea7b70 18225 ((struct objfile *) 0x82e69d0)
b383017d 18226 @{ symtab /home/gnu/src/gdb/dwarf2read.c
44ea7b70
JB
18227 ((struct symtab *) 0x86c1f38)
18228 dirname (null)
18229 fullname (null)
18230 blockvector ((struct blockvector *) 0x86c1bd0) (primary)
1b39d5c0 18231 linetable ((struct linetable *) 0x8370fa0)
44ea7b70
JB
18232 debugformat DWARF 2
18233 @}
18234@}
b383017d 18235(@value{GDBP})
44ea7b70 18236@end smallexample
44ea7b70 18237
f2403c39
AB
18238@kindex maint info line-table
18239@cindex listing @value{GDBN}'s internal line tables
18240@cindex line tables, listing @value{GDBN}'s internal
18241@item maint info line-table @r{[} @var{regexp} @r{]}
18242
18243List the @code{struct linetable} from all @code{struct symtab}
18244instances whose name matches @var{regexp}. If @var{regexp} is not
18245given, list the @code{struct linetable} from all @code{struct symtab}.
18246
f57d2163
DE
18247@kindex maint set symbol-cache-size
18248@cindex symbol cache size
18249@item maint set symbol-cache-size @var{size}
18250Set the size of the symbol cache to @var{size}.
18251The default size is intended to be good enough for debugging
18252most applications. This option exists to allow for experimenting
18253with different sizes.
18254
18255@kindex maint show symbol-cache-size
18256@item maint show symbol-cache-size
18257Show the size of the symbol cache.
18258
18259@kindex maint print symbol-cache
18260@cindex symbol cache, printing its contents
18261@item maint print symbol-cache
18262Print the contents of the symbol cache.
18263This is useful when debugging symbol cache issues.
18264
18265@kindex maint print symbol-cache-statistics
18266@cindex symbol cache, printing usage statistics
18267@item maint print symbol-cache-statistics
18268Print symbol cache usage statistics.
18269This helps determine how well the cache is being utilized.
18270
18271@kindex maint flush-symbol-cache
18272@cindex symbol cache, flushing
18273@item maint flush-symbol-cache
18274Flush the contents of the symbol cache, all entries are removed.
18275This command is useful when debugging the symbol cache.
18276It is also useful when collecting performance data.
18277
18278@end table
6a3ca067 18279
6d2ebf8b 18280@node Altering
c906108c
SS
18281@chapter Altering Execution
18282
18283Once you think you have found an error in your program, you might want to
18284find out for certain whether correcting the apparent error would lead to
18285correct results in the rest of the run. You can find the answer by
18286experiment, using the @value{GDBN} features for altering execution of the
18287program.
18288
18289For example, you can store new values into variables or memory
7a292a7a
SS
18290locations, give your program a signal, restart it at a different
18291address, or even return prematurely from a function.
c906108c
SS
18292
18293@menu
18294* Assignment:: Assignment to variables
18295* Jumping:: Continuing at a different address
c906108c 18296* Signaling:: Giving your program a signal
c906108c
SS
18297* Returning:: Returning from a function
18298* Calling:: Calling your program's functions
18299* Patching:: Patching your program
bb2ec1b3 18300* Compiling and Injecting Code:: Compiling and injecting code in @value{GDBN}
c906108c
SS
18301@end menu
18302
6d2ebf8b 18303@node Assignment
79a6e687 18304@section Assignment to Variables
c906108c
SS
18305
18306@cindex assignment
18307@cindex setting variables
18308To alter the value of a variable, evaluate an assignment expression.
18309@xref{Expressions, ,Expressions}. For example,
18310
474c8240 18311@smallexample
c906108c 18312print x=4
474c8240 18313@end smallexample
c906108c
SS
18314
18315@noindent
18316stores the value 4 into the variable @code{x}, and then prints the
5d161b24 18317value of the assignment expression (which is 4).
c906108c
SS
18318@xref{Languages, ,Using @value{GDBN} with Different Languages}, for more
18319information on operators in supported languages.
c906108c
SS
18320
18321@kindex set variable
18322@cindex variables, setting
18323If you are not interested in seeing the value of the assignment, use the
18324@code{set} command instead of the @code{print} command. @code{set} is
18325really the same as @code{print} except that the expression's value is
18326not printed and is not put in the value history (@pxref{Value History,
79a6e687 18327,Value History}). The expression is evaluated only for its effects.
c906108c 18328
c906108c
SS
18329If the beginning of the argument string of the @code{set} command
18330appears identical to a @code{set} subcommand, use the @code{set
18331variable} command instead of just @code{set}. This command is identical
18332to @code{set} except for its lack of subcommands. For example, if your
18333program has a variable @code{width}, you get an error if you try to set
18334a new value with just @samp{set width=13}, because @value{GDBN} has the
18335command @code{set width}:
18336
474c8240 18337@smallexample
c906108c
SS
18338(@value{GDBP}) whatis width
18339type = double
18340(@value{GDBP}) p width
18341$4 = 13
18342(@value{GDBP}) set width=47
18343Invalid syntax in expression.
474c8240 18344@end smallexample
c906108c
SS
18345
18346@noindent
18347The invalid expression, of course, is @samp{=47}. In
18348order to actually set the program's variable @code{width}, use
18349
474c8240 18350@smallexample
c906108c 18351(@value{GDBP}) set var width=47
474c8240 18352@end smallexample
53a5351d 18353
c906108c
SS
18354Because the @code{set} command has many subcommands that can conflict
18355with the names of program variables, it is a good idea to use the
18356@code{set variable} command instead of just @code{set}. For example, if
18357your program has a variable @code{g}, you run into problems if you try
18358to set a new value with just @samp{set g=4}, because @value{GDBN} has
18359the command @code{set gnutarget}, abbreviated @code{set g}:
18360
474c8240 18361@smallexample
c906108c
SS
18362@group
18363(@value{GDBP}) whatis g
18364type = double
18365(@value{GDBP}) p g
18366$1 = 1
18367(@value{GDBP}) set g=4
2df3850c 18368(@value{GDBP}) p g
c906108c
SS
18369$2 = 1
18370(@value{GDBP}) r
18371The program being debugged has been started already.
18372Start it from the beginning? (y or n) y
18373Starting program: /home/smith/cc_progs/a.out
6d2ebf8b
SS
18374"/home/smith/cc_progs/a.out": can't open to read symbols:
18375 Invalid bfd target.
c906108c
SS
18376(@value{GDBP}) show g
18377The current BFD target is "=4".
18378@end group
474c8240 18379@end smallexample
c906108c
SS
18380
18381@noindent
18382The program variable @code{g} did not change, and you silently set the
18383@code{gnutarget} to an invalid value. In order to set the variable
18384@code{g}, use
18385
474c8240 18386@smallexample
c906108c 18387(@value{GDBP}) set var g=4
474c8240 18388@end smallexample
c906108c
SS
18389
18390@value{GDBN} allows more implicit conversions in assignments than C; you can
18391freely store an integer value into a pointer variable or vice versa,
18392and you can convert any structure to any other structure that is the
18393same length or shorter.
18394@comment FIXME: how do structs align/pad in these conversions?
18395@comment /doc@cygnus.com 18dec1990
18396
18397To store values into arbitrary places in memory, use the @samp{@{@dots{}@}}
18398construct to generate a value of specified type at a specified address
18399(@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers
18400to memory location @code{0x83040} as an integer (which implies a certain size
18401and representation in memory), and
18402
474c8240 18403@smallexample
c906108c 18404set @{int@}0x83040 = 4
474c8240 18405@end smallexample
c906108c
SS
18406
18407@noindent
18408stores the value 4 into that memory location.
18409
6d2ebf8b 18410@node Jumping
79a6e687 18411@section Continuing at a Different Address
c906108c
SS
18412
18413Ordinarily, when you continue your program, you do so at the place where
18414it stopped, with the @code{continue} command. You can instead continue at
18415an address of your own choosing, with the following commands:
18416
18417@table @code
18418@kindex jump
c1d780c2 18419@kindex j @r{(@code{jump})}
629500fa 18420@item jump @var{location}
c1d780c2 18421@itemx j @var{location}
629500fa
KS
18422Resume execution at @var{location}. Execution stops again immediately
18423if there is a breakpoint there. @xref{Specify Location}, for a description
18424of the different forms of @var{location}. It is common
2a25a5ba
EZ
18425practice to use the @code{tbreak} command in conjunction with
18426@code{jump}. @xref{Set Breaks, ,Setting Breakpoints}.
c906108c
SS
18427
18428The @code{jump} command does not change the current stack frame, or
18429the stack pointer, or the contents of any memory location or any
629500fa 18430register other than the program counter. If @var{location} is in
c906108c
SS
18431a different function from the one currently executing, the results may
18432be bizarre if the two functions expect different patterns of arguments or
18433of local variables. For this reason, the @code{jump} command requests
18434confirmation if the specified line is not in the function currently
18435executing. However, even bizarre results are predictable if you are
18436well acquainted with the machine-language code of your program.
c906108c
SS
18437@end table
18438
53a5351d
JM
18439On many systems, you can get much the same effect as the @code{jump}
18440command by storing a new value into the register @code{$pc}. The
18441difference is that this does not start your program running; it only
18442changes the address of where it @emph{will} run when you continue. For
18443example,
c906108c 18444
474c8240 18445@smallexample
c906108c 18446set $pc = 0x485
474c8240 18447@end smallexample
c906108c
SS
18448
18449@noindent
18450makes the next @code{continue} command or stepping command execute at
18451address @code{0x485}, rather than at the address where your program stopped.
79a6e687 18452@xref{Continuing and Stepping, ,Continuing and Stepping}.
c906108c
SS
18453
18454The most common occasion to use the @code{jump} command is to back
18455up---perhaps with more breakpoints set---over a portion of a program
18456that has already executed, in order to examine its execution in more
18457detail.
18458
c906108c 18459@c @group
6d2ebf8b 18460@node Signaling
79a6e687 18461@section Giving your Program a Signal
9c16f35a 18462@cindex deliver a signal to a program
c906108c
SS
18463
18464@table @code
18465@kindex signal
18466@item signal @var{signal}
70509625 18467Resume execution where your program is stopped, but immediately give it the
697aa1b7 18468signal @var{signal}. The @var{signal} can be the name or the number of a
c906108c
SS
18469signal. For example, on many systems @code{signal 2} and @code{signal
18470SIGINT} are both ways of sending an interrupt signal.
18471
18472Alternatively, if @var{signal} is zero, continue execution without
18473giving a signal. This is useful when your program stopped on account of
ae606bee 18474a signal and would ordinarily see the signal when resumed with the
c906108c
SS
18475@code{continue} command; @samp{signal 0} causes it to resume without a
18476signal.
18477
70509625
PA
18478@emph{Note:} When resuming a multi-threaded program, @var{signal} is
18479delivered to the currently selected thread, not the thread that last
18480reported a stop. This includes the situation where a thread was
18481stopped due to a signal. So if you want to continue execution
18482suppressing the signal that stopped a thread, you should select that
18483same thread before issuing the @samp{signal 0} command. If you issue
18484the @samp{signal 0} command with another thread as the selected one,
18485@value{GDBN} detects that and asks for confirmation.
18486
c906108c
SS
18487Invoking the @code{signal} command is not the same as invoking the
18488@code{kill} utility from the shell. Sending a signal with @code{kill}
18489causes @value{GDBN} to decide what to do with the signal depending on
18490the signal handling tables (@pxref{Signals}). The @code{signal} command
18491passes the signal directly to your program.
18492
81219e53
DE
18493@code{signal} does not repeat when you press @key{RET} a second time
18494after executing the command.
18495
18496@kindex queue-signal
18497@item queue-signal @var{signal}
18498Queue @var{signal} to be delivered immediately to the current thread
18499when execution of the thread resumes. The @var{signal} can be the name or
18500the number of a signal. For example, on many systems @code{signal 2} and
18501@code{signal SIGINT} are both ways of sending an interrupt signal.
18502The handling of the signal must be set to pass the signal to the program,
18503otherwise @value{GDBN} will report an error.
18504You can control the handling of signals from @value{GDBN} with the
18505@code{handle} command (@pxref{Signals}).
18506
18507Alternatively, if @var{signal} is zero, any currently queued signal
18508for the current thread is discarded and when execution resumes no signal
18509will be delivered. This is useful when your program stopped on account
18510of a signal and would ordinarily see the signal when resumed with the
18511@code{continue} command.
18512
18513This command differs from the @code{signal} command in that the signal
18514is just queued, execution is not resumed. And @code{queue-signal} cannot
18515be used to pass a signal whose handling state has been set to @code{nopass}
18516(@pxref{Signals}).
18517@end table
18518@c @end group
c906108c 18519
e5f8a7cc
PA
18520@xref{stepping into signal handlers}, for information on how stepping
18521commands behave when the thread has a signal queued.
18522
6d2ebf8b 18523@node Returning
79a6e687 18524@section Returning from a Function
c906108c
SS
18525
18526@table @code
18527@cindex returning from a function
18528@kindex return
18529@item return
18530@itemx return @var{expression}
18531You can cancel execution of a function call with the @code{return}
18532command. If you give an
18533@var{expression} argument, its value is used as the function's return
18534value.
18535@end table
18536
18537When you use @code{return}, @value{GDBN} discards the selected stack frame
18538(and all frames within it). You can think of this as making the
18539discarded frame return prematurely. If you wish to specify a value to
18540be returned, give that value as the argument to @code{return}.
18541
18542This pops the selected stack frame (@pxref{Selection, ,Selecting a
79a6e687 18543Frame}), and any other frames inside of it, leaving its caller as the
c906108c
SS
18544innermost remaining frame. That frame becomes selected. The
18545specified value is stored in the registers used for returning values
18546of functions.
18547
18548The @code{return} command does not resume execution; it leaves the
18549program stopped in the state that would exist if the function had just
18550returned. In contrast, the @code{finish} command (@pxref{Continuing
79a6e687 18551and Stepping, ,Continuing and Stepping}) resumes execution until the
c906108c
SS
18552selected stack frame returns naturally.
18553
61ff14c6
JK
18554@value{GDBN} needs to know how the @var{expression} argument should be set for
18555the inferior. The concrete registers assignment depends on the OS ABI and the
18556type being returned by the selected stack frame. For example it is common for
18557OS ABI to return floating point values in FPU registers while integer values in
18558CPU registers. Still some ABIs return even floating point values in CPU
18559registers. Larger integer widths (such as @code{long long int}) also have
18560specific placement rules. @value{GDBN} already knows the OS ABI from its
18561current target so it needs to find out also the type being returned to make the
18562assignment into the right register(s).
18563
18564Normally, the selected stack frame has debug info. @value{GDBN} will always
18565use the debug info instead of the implicit type of @var{expression} when the
18566debug info is available. For example, if you type @kbd{return -1}, and the
18567function in the current stack frame is declared to return a @code{long long
18568int}, @value{GDBN} transparently converts the implicit @code{int} value of -1
18569into a @code{long long int}:
18570
18571@smallexample
18572Breakpoint 1, func () at gdb.base/return-nodebug.c:29
1857329 return 31;
18574(@value{GDBP}) return -1
18575Make func return now? (y or n) y
18576#0 0x004004f6 in main () at gdb.base/return-nodebug.c:43
1857743 printf ("result=%lld\n", func ());
18578(@value{GDBP})
18579@end smallexample
18580
18581However, if the selected stack frame does not have a debug info, e.g., if the
18582function was compiled without debug info, @value{GDBN} has to find out the type
18583to return from user. Specifying a different type by mistake may set the value
18584in different inferior registers than the caller code expects. For example,
18585typing @kbd{return -1} with its implicit type @code{int} would set only a part
18586of a @code{long long int} result for a debug info less function (on 32-bit
18587architectures). Therefore the user is required to specify the return type by
18588an appropriate cast explicitly:
18589
18590@smallexample
18591Breakpoint 2, 0x0040050b in func ()
18592(@value{GDBP}) return -1
18593Return value type not available for selected stack frame.
18594Please use an explicit cast of the value to return.
18595(@value{GDBP}) return (long long int) -1
18596Make selected stack frame return now? (y or n) y
18597#0 0x00400526 in main ()
18598(@value{GDBP})
18599@end smallexample
18600
6d2ebf8b 18601@node Calling
79a6e687 18602@section Calling Program Functions
c906108c 18603
f8568604 18604@table @code
c906108c 18605@cindex calling functions
f8568604
EZ
18606@cindex inferior functions, calling
18607@item print @var{expr}
d3e8051b 18608Evaluate the expression @var{expr} and display the resulting value.
697aa1b7 18609The expression may include calls to functions in the program being
f8568604
EZ
18610debugged.
18611
c906108c 18612@kindex call
c906108c
SS
18613@item call @var{expr}
18614Evaluate the expression @var{expr} without displaying @code{void}
18615returned values.
c906108c
SS
18616
18617You can use this variant of the @code{print} command if you want to
f8568604
EZ
18618execute a function from your program that does not return anything
18619(a.k.a.@: @dfn{a void function}), but without cluttering the output
18620with @code{void} returned values that @value{GDBN} will otherwise
18621print. If the result is not void, it is printed and saved in the
18622value history.
18623@end table
18624
9c16f35a
EZ
18625It is possible for the function you call via the @code{print} or
18626@code{call} command to generate a signal (e.g., if there's a bug in
18627the function, or if you passed it incorrect arguments). What happens
18628in that case is controlled by the @code{set unwindonsignal} command.
18629
7cd1089b
PM
18630Similarly, with a C@t{++} program it is possible for the function you
18631call via the @code{print} or @code{call} command to generate an
18632exception that is not handled due to the constraints of the dummy
18633frame. In this case, any exception that is raised in the frame, but has
18634an out-of-frame exception handler will not be found. GDB builds a
18635dummy-frame for the inferior function call, and the unwinder cannot
18636seek for exception handlers outside of this dummy-frame. What happens
18637in that case is controlled by the
18638@code{set unwind-on-terminating-exception} command.
18639
9c16f35a
EZ
18640@table @code
18641@item set unwindonsignal
18642@kindex set unwindonsignal
18643@cindex unwind stack in called functions
18644@cindex call dummy stack unwinding
18645Set unwinding of the stack if a signal is received while in a function
18646that @value{GDBN} called in the program being debugged. If set to on,
18647@value{GDBN} unwinds the stack it created for the call and restores
18648the context to what it was before the call. If set to off (the
18649default), @value{GDBN} stops in the frame where the signal was
18650received.
18651
18652@item show unwindonsignal
18653@kindex show unwindonsignal
18654Show the current setting of stack unwinding in the functions called by
18655@value{GDBN}.
7cd1089b
PM
18656
18657@item set unwind-on-terminating-exception
18658@kindex set unwind-on-terminating-exception
18659@cindex unwind stack in called functions with unhandled exceptions
18660@cindex call dummy stack unwinding on unhandled exception.
18661Set unwinding of the stack if a C@t{++} exception is raised, but left
18662unhandled while in a function that @value{GDBN} called in the program being
18663debugged. If set to on (the default), @value{GDBN} unwinds the stack
18664it created for the call and restores the context to what it was before
18665the call. If set to off, @value{GDBN} the exception is delivered to
18666the default C@t{++} exception handler and the inferior terminated.
18667
18668@item show unwind-on-terminating-exception
18669@kindex show unwind-on-terminating-exception
18670Show the current setting of stack unwinding in the functions called by
18671@value{GDBN}.
18672
9c16f35a
EZ
18673@end table
18674
d69cf9b2
PA
18675@subsection Calling functions with no debug info
18676
18677@cindex no debug info functions
18678Sometimes, a function you wish to call is missing debug information.
18679In such case, @value{GDBN} does not know the type of the function,
18680including the types of the function's parameters. To avoid calling
18681the inferior function incorrectly, which could result in the called
18682function functioning erroneously and even crash, @value{GDBN} refuses
18683to call the function unless you tell it the type of the function.
18684
18685For prototyped (i.e.@: ANSI/ISO style) functions, there are two ways
18686to do that. The simplest is to cast the call to the function's
18687declared return type. For example:
18688
18689@smallexample
18690(@value{GDBP}) p getenv ("PATH")
18691'getenv' has unknown return type; cast the call to its declared return type
18692(@value{GDBP}) p (char *) getenv ("PATH")
18693$1 = 0x7fffffffe7ba "/usr/local/bin:/"...
18694@end smallexample
18695
18696Casting the return type of a no-debug function is equivalent to
18697casting the function to a pointer to a prototyped function that has a
18698prototype that matches the types of the passed-in arguments, and
18699calling that. I.e., the call above is equivalent to:
18700
18701@smallexample
18702(@value{GDBP}) p ((char * (*) (const char *)) getenv) ("PATH")
18703@end smallexample
18704
18705@noindent
18706and given this prototyped C or C++ function with float parameters:
18707
18708@smallexample
18709float multiply (float v1, float v2) @{ return v1 * v2; @}
18710@end smallexample
18711
18712@noindent
18713these calls are equivalent:
18714
18715@smallexample
18716(@value{GDBP}) p (float) multiply (2.0f, 3.0f)
18717(@value{GDBP}) p ((float (*) (float, float)) multiply) (2.0f, 3.0f)
18718@end smallexample
18719
18720If the function you wish to call is declared as unprototyped (i.e.@:
18721old K&R style), you must use the cast-to-function-pointer syntax, so
18722that @value{GDBN} knows that it needs to apply default argument
18723promotions (promote float arguments to double). @xref{ABI, float
18724promotion}. For example, given this unprototyped C function with
18725float parameters, and no debug info:
18726
18727@smallexample
18728float
18729multiply_noproto (v1, v2)
18730 float v1, v2;
18731@{
18732 return v1 * v2;
18733@}
18734@end smallexample
18735
18736@noindent
18737you call it like this:
18738
18739@smallexample
18740 (@value{GDBP}) p ((float (*) ()) multiply_noproto) (2.0f, 3.0f)
18741@end smallexample
c906108c 18742
6d2ebf8b 18743@node Patching
79a6e687 18744@section Patching Programs
7a292a7a 18745
c906108c
SS
18746@cindex patching binaries
18747@cindex writing into executables
c906108c 18748@cindex writing into corefiles
c906108c 18749
7a292a7a
SS
18750By default, @value{GDBN} opens the file containing your program's
18751executable code (or the corefile) read-only. This prevents accidental
18752alterations to machine code; but it also prevents you from intentionally
18753patching your program's binary.
c906108c
SS
18754
18755If you'd like to be able to patch the binary, you can specify that
18756explicitly with the @code{set write} command. For example, you might
18757want to turn on internal debugging flags, or even to make emergency
18758repairs.
18759
18760@table @code
18761@kindex set write
18762@item set write on
18763@itemx set write off
7a292a7a 18764If you specify @samp{set write on}, @value{GDBN} opens executable and
20924a55 18765core files for both reading and writing; if you specify @kbd{set write
c906108c
SS
18766off} (the default), @value{GDBN} opens them read-only.
18767
18768If you have already loaded a file, you must load it again (using the
7a292a7a
SS
18769@code{exec-file} or @code{core-file} command) after changing @code{set
18770write}, for your new setting to take effect.
c906108c
SS
18771
18772@item show write
18773@kindex show write
7a292a7a
SS
18774Display whether executable files and core files are opened for writing
18775as well as reading.
c906108c
SS
18776@end table
18777
bb2ec1b3
TT
18778@node Compiling and Injecting Code
18779@section Compiling and injecting code in @value{GDBN}
18780@cindex injecting code
18781@cindex writing into executables
18782@cindex compiling code
18783
18784@value{GDBN} supports on-demand compilation and code injection into
18785programs running under @value{GDBN}. GCC 5.0 or higher built with
18786@file{libcc1.so} must be installed for this functionality to be enabled.
18787This functionality is implemented with the following commands.
18788
18789@table @code
18790@kindex compile code
18791@item compile code @var{source-code}
18792@itemx compile code -raw @var{--} @var{source-code}
18793Compile @var{source-code} with the compiler language found as the current
18794language in @value{GDBN} (@pxref{Languages}). If compilation and
18795injection is not supported with the current language specified in
18796@value{GDBN}, or the compiler does not support this feature, an error
18797message will be printed. If @var{source-code} compiles and links
18798successfully, @value{GDBN} will load the object-code emitted,
18799and execute it within the context of the currently selected inferior.
18800It is important to note that the compiled code is executed immediately.
18801After execution, the compiled code is removed from @value{GDBN} and any
18802new types or variables you have defined will be deleted.
18803
18804The command allows you to specify @var{source-code} in two ways.
18805The simplest method is to provide a single line of code to the command.
18806E.g.:
18807
18808@smallexample
18809compile code printf ("hello world\n");
18810@end smallexample
18811
18812If you specify options on the command line as well as source code, they
18813may conflict. The @samp{--} delimiter can be used to separate options
18814from actual source code. E.g.:
18815
18816@smallexample
18817compile code -r -- printf ("hello world\n");
18818@end smallexample
18819
18820Alternatively you can enter source code as multiple lines of text. To
18821enter this mode, invoke the @samp{compile code} command without any text
18822following the command. This will start the multiple-line editor and
18823allow you to type as many lines of source code as required. When you
18824have completed typing, enter @samp{end} on its own line to exit the
18825editor.
18826
18827@smallexample
18828compile code
18829>printf ("hello\n");
18830>printf ("world\n");
18831>end
18832@end smallexample
18833
18834Specifying @samp{-raw}, prohibits @value{GDBN} from wrapping the
18835provided @var{source-code} in a callable scope. In this case, you must
18836specify the entry point of the code by defining a function named
18837@code{_gdb_expr_}. The @samp{-raw} code cannot access variables of the
18838inferior. Using @samp{-raw} option may be needed for example when
18839@var{source-code} requires @samp{#include} lines which may conflict with
18840inferior symbols otherwise.
18841
18842@kindex compile file
18843@item compile file @var{filename}
18844@itemx compile file -raw @var{filename}
18845Like @code{compile code}, but take the source code from @var{filename}.
18846
18847@smallexample
18848compile file /home/user/example.c
18849@end smallexample
18850@end table
18851
36de76f9
JK
18852@table @code
18853@item compile print @var{expr}
18854@itemx compile print /@var{f} @var{expr}
18855Compile and execute @var{expr} with the compiler language found as the
18856current language in @value{GDBN} (@pxref{Languages}). By default the
18857value of @var{expr} is printed in a format appropriate to its data type;
18858you can choose a different format by specifying @samp{/@var{f}}, where
18859@var{f} is a letter specifying the format; see @ref{Output Formats,,Output
18860Formats}.
18861
18862@item compile print
18863@itemx compile print /@var{f}
18864@cindex reprint the last value
18865Alternatively you can enter the expression (source code producing it) as
18866multiple lines of text. To enter this mode, invoke the @samp{compile print}
18867command without any text following the command. This will start the
18868multiple-line editor.
18869@end table
18870
e7a8570f
JK
18871@noindent
18872The process of compiling and injecting the code can be inspected using:
18873
18874@table @code
18875@anchor{set debug compile}
18876@item set debug compile
18877@cindex compile command debugging info
18878Turns on or off display of @value{GDBN} process of compiling and
18879injecting the code. The default is off.
18880
18881@item show debug compile
18882Displays the current state of displaying @value{GDBN} process of
18883compiling and injecting the code.
078a0207
KS
18884
18885@anchor{set debug compile-cplus-types}
18886@item set debug compile-cplus-types
18887@cindex compile C@t{++} type conversion
18888Turns on or off the display of C@t{++} type conversion debugging information.
18889The default is off.
18890
18891@item show debug compile-cplus-types
18892Displays the current state of displaying debugging information for
18893C@t{++} type conversion.
e7a8570f
JK
18894@end table
18895
18896@subsection Compilation options for the @code{compile} command
18897
18898@value{GDBN} needs to specify the right compilation options for the code
18899to be injected, in part to make its ABI compatible with the inferior
18900and in part to make the injected code compatible with @value{GDBN}'s
18901injecting process.
18902
18903@noindent
18904The options used, in increasing precedence:
18905
18906@table @asis
18907@item target architecture and OS options (@code{gdbarch})
18908These options depend on target processor type and target operating
18909system, usually they specify at least 32-bit (@code{-m32}) or 64-bit
18910(@code{-m64}) compilation option.
18911
18912@item compilation options recorded in the target
18913@value{NGCC} (since version 4.7) stores the options used for compilation
18914into @code{DW_AT_producer} part of DWARF debugging information according
18915to the @value{NGCC} option @code{-grecord-gcc-switches}. One has to
18916explicitly specify @code{-g} during inferior compilation otherwise
18917@value{NGCC} produces no DWARF. This feature is only relevant for
18918platforms where @code{-g} produces DWARF by default, otherwise one may
18919try to enforce DWARF by using @code{-gdwarf-4}.
18920
18921@item compilation options set by @code{set compile-args}
18922@end table
18923
18924@noindent
18925You can override compilation options using the following command:
18926
18927@table @code
18928@item set compile-args
18929@cindex compile command options override
18930Set compilation options used for compiling and injecting code with the
18931@code{compile} commands. These options override any conflicting ones
18932from the target architecture and/or options stored during inferior
18933compilation.
18934
18935@item show compile-args
18936Displays the current state of compilation options override.
18937This does not show all the options actually used during compilation,
18938use @ref{set debug compile} for that.
18939@end table
18940
bb2ec1b3
TT
18941@subsection Caveats when using the @code{compile} command
18942
18943There are a few caveats to keep in mind when using the @code{compile}
18944command. As the caveats are different per language, the table below
18945highlights specific issues on a per language basis.
18946
18947@table @asis
18948@item C code examples and caveats
18949When the language in @value{GDBN} is set to @samp{C}, the compiler will
18950attempt to compile the source code with a @samp{C} compiler. The source
18951code provided to the @code{compile} command will have much the same
18952access to variables and types as it normally would if it were part of
18953the program currently being debugged in @value{GDBN}.
18954
18955Below is a sample program that forms the basis of the examples that
18956follow. This program has been compiled and loaded into @value{GDBN},
18957much like any other normal debugging session.
18958
18959@smallexample
18960void function1 (void)
18961@{
18962 int i = 42;
18963 printf ("function 1\n");
18964@}
18965
18966void function2 (void)
18967@{
18968 int j = 12;
18969 function1 ();
18970@}
18971
18972int main(void)
18973@{
18974 int k = 6;
18975 int *p;
18976 function2 ();
18977 return 0;
18978@}
18979@end smallexample
18980
18981For the purposes of the examples in this section, the program above has
18982been compiled, loaded into @value{GDBN}, stopped at the function
18983@code{main}, and @value{GDBN} is awaiting input from the user.
18984
18985To access variables and types for any program in @value{GDBN}, the
18986program must be compiled and packaged with debug information. The
18987@code{compile} command is not an exception to this rule. Without debug
18988information, you can still use the @code{compile} command, but you will
18989be very limited in what variables and types you can access.
18990
18991So with that in mind, the example above has been compiled with debug
18992information enabled. The @code{compile} command will have access to
18993all variables and types (except those that may have been optimized
18994out). Currently, as @value{GDBN} has stopped the program in the
18995@code{main} function, the @code{compile} command would have access to
18996the variable @code{k}. You could invoke the @code{compile} command
18997and type some source code to set the value of @code{k}. You can also
18998read it, or do anything with that variable you would normally do in
18999@code{C}. Be aware that changes to inferior variables in the
19000@code{compile} command are persistent. In the following example:
19001
19002@smallexample
19003compile code k = 3;
19004@end smallexample
19005
19006@noindent
19007the variable @code{k} is now 3. It will retain that value until
19008something else in the example program changes it, or another
19009@code{compile} command changes it.
19010
19011Normal scope and access rules apply to source code compiled and
19012injected by the @code{compile} command. In the example, the variables
19013@code{j} and @code{k} are not accessible yet, because the program is
19014currently stopped in the @code{main} function, where these variables
19015are not in scope. Therefore, the following command
19016
19017@smallexample
19018compile code j = 3;
19019@end smallexample
19020
19021@noindent
19022will result in a compilation error message.
19023
19024Once the program is continued, execution will bring these variables in
19025scope, and they will become accessible; then the code you specify via
19026the @code{compile} command will be able to access them.
19027
19028You can create variables and types with the @code{compile} command as
19029part of your source code. Variables and types that are created as part
19030of the @code{compile} command are not visible to the rest of the program for
19031the duration of its run. This example is valid:
19032
19033@smallexample
19034compile code int ff = 5; printf ("ff is %d\n", ff);
19035@end smallexample
19036
19037However, if you were to type the following into @value{GDBN} after that
19038command has completed:
19039
19040@smallexample
19041compile code printf ("ff is %d\n'', ff);
19042@end smallexample
19043
19044@noindent
19045a compiler error would be raised as the variable @code{ff} no longer
19046exists. Object code generated and injected by the @code{compile}
19047command is removed when its execution ends. Caution is advised
19048when assigning to program variables values of variables created by the
19049code submitted to the @code{compile} command. This example is valid:
19050
19051@smallexample
19052compile code int ff = 5; k = ff;
19053@end smallexample
19054
19055The value of the variable @code{ff} is assigned to @code{k}. The variable
19056@code{k} does not require the existence of @code{ff} to maintain the value
19057it has been assigned. However, pointers require particular care in
19058assignment. If the source code compiled with the @code{compile} command
19059changed the address of a pointer in the example program, perhaps to a
19060variable created in the @code{compile} command, that pointer would point
19061to an invalid location when the command exits. The following example
19062would likely cause issues with your debugged program:
19063
19064@smallexample
19065compile code int ff = 5; p = &ff;
19066@end smallexample
19067
19068In this example, @code{p} would point to @code{ff} when the
19069@code{compile} command is executing the source code provided to it.
19070However, as variables in the (example) program persist with their
19071assigned values, the variable @code{p} would point to an invalid
19072location when the command exists. A general rule should be followed
19073in that you should either assign @code{NULL} to any assigned pointers,
19074or restore a valid location to the pointer before the command exits.
19075
19076Similar caution must be exercised with any structs, unions, and typedefs
19077defined in @code{compile} command. Types defined in the @code{compile}
19078command will no longer be available in the next @code{compile} command.
19079Therefore, if you cast a variable to a type defined in the
19080@code{compile} command, care must be taken to ensure that any future
19081need to resolve the type can be achieved.
19082
19083@smallexample
19084(gdb) compile code static struct a @{ int a; @} v = @{ 42 @}; argv = &v;
19085(gdb) compile code printf ("%d\n", ((struct a *) argv)->a);
19086gdb command line:1:36: error: dereferencing pointer to incomplete type ‘struct a’
19087Compilation failed.
19088(gdb) compile code struct a @{ int a; @}; printf ("%d\n", ((struct a *) argv)->a);
1908942
19090@end smallexample
19091
19092Variables that have been optimized away by the compiler are not
19093accessible to the code submitted to the @code{compile} command.
19094Access to those variables will generate a compiler error which @value{GDBN}
19095will print to the console.
19096@end table
19097
e7a8570f
JK
19098@subsection Compiler search for the @code{compile} command
19099
6e41ddec
JK
19100@value{GDBN} needs to find @value{NGCC} for the inferior being debugged
19101which may not be obvious for remote targets of different architecture
19102than where @value{GDBN} is running. Environment variable @code{PATH} on
e7a8570f 19103@value{GDBN} host is searched for @value{NGCC} binary matching the
6e41ddec
JK
19104target architecture and operating system. This search can be overriden
19105by @code{set compile-gcc} @value{GDBN} command below. @code{PATH} is
19106taken from shell that executed @value{GDBN}, it is not the value set by
19107@value{GDBN} command @code{set environment}). @xref{Environment}.
19108
e7a8570f
JK
19109
19110Specifically @code{PATH} is searched for binaries matching regular expression
19111@code{@var{arch}(-[^-]*)?-@var{os}-gcc} according to the inferior target being
19112debugged. @var{arch} is processor name --- multiarch is supported, so for
19113example both @code{i386} and @code{x86_64} targets look for pattern
19114@code{(x86_64|i.86)} and both @code{s390} and @code{s390x} targets look
19115for pattern @code{s390x?}. @var{os} is currently supported only for
19116pattern @code{linux(-gnu)?}.
19117
6e41ddec
JK
19118On Posix hosts the compiler driver @value{GDBN} needs to find also
19119shared library @file{libcc1.so} from the compiler. It is searched in
19120default shared library search path (overridable with usual environment
19121variable @code{LD_LIBRARY_PATH}), unrelated to @code{PATH} or @code{set
19122compile-gcc} settings. Contrary to it @file{libcc1plugin.so} is found
19123according to the installation of the found compiler --- as possibly
19124specified by the @code{set compile-gcc} command.
19125
19126@table @code
19127@item set compile-gcc
19128@cindex compile command driver filename override
19129Set compilation command used for compiling and injecting code with the
19130@code{compile} commands. If this option is not set (it is set to
19131an empty string), the search described above will occur --- that is the
19132default.
19133
19134@item show compile-gcc
19135Displays the current compile command @value{NGCC} driver filename.
19136If set, it is the main command @command{gcc}, found usually for example
19137under name @file{x86_64-linux-gnu-gcc}.
19138@end table
19139
6d2ebf8b 19140@node GDB Files
c906108c
SS
19141@chapter @value{GDBN} Files
19142
7a292a7a
SS
19143@value{GDBN} needs to know the file name of the program to be debugged,
19144both in order to read its symbol table and in order to start your
19145program. To debug a core dump of a previous run, you must also tell
19146@value{GDBN} the name of the core dump file.
c906108c
SS
19147
19148@menu
19149* Files:: Commands to specify files
2b4bf6af 19150* File Caching:: Information about @value{GDBN}'s file caching
5b5d99cf 19151* Separate Debug Files:: Debugging information in separate files
608e2dbb 19152* MiniDebugInfo:: Debugging information in a special section
9291a0cd 19153* Index Files:: Index files speed up GDB
c906108c 19154* Symbol Errors:: Errors reading symbol files
b14b1491 19155* Data Files:: GDB data files
c906108c
SS
19156@end menu
19157
6d2ebf8b 19158@node Files
79a6e687 19159@section Commands to Specify Files
c906108c 19160
7a292a7a 19161@cindex symbol table
c906108c 19162@cindex core dump file
7a292a7a
SS
19163
19164You may want to specify executable and core dump file names. The usual
19165way to do this is at start-up time, using the arguments to
19166@value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and
19167Out of @value{GDBN}}).
c906108c
SS
19168
19169Occasionally it is necessary to change to a different file during a
397ca115
EZ
19170@value{GDBN} session. Or you may run @value{GDBN} and forget to
19171specify a file you want to use. Or you are debugging a remote target
79a6e687
BW
19172via @code{gdbserver} (@pxref{Server, file, Using the @code{gdbserver}
19173Program}). In these situations the @value{GDBN} commands to specify
0869d01b 19174new files are useful.
c906108c
SS
19175
19176@table @code
19177@cindex executable file
19178@kindex file
19179@item file @var{filename}
19180Use @var{filename} as the program to be debugged. It is read for its
19181symbols and for the contents of pure memory. It is also the program
19182executed when you use the @code{run} command. If you do not specify a
5d161b24
DB
19183directory and the file is not found in the @value{GDBN} working directory,
19184@value{GDBN} uses the environment variable @code{PATH} as a list of
19185directories to search, just as the shell does when looking for a program
19186to run. You can change the value of this variable, for both @value{GDBN}
c906108c
SS
19187and your program, using the @code{path} command.
19188
fc8be69e
EZ
19189@cindex unlinked object files
19190@cindex patching object files
19191You can load unlinked object @file{.o} files into @value{GDBN} using
19192the @code{file} command. You will not be able to ``run'' an object
19193file, but you can disassemble functions and inspect variables. Also,
19194if the underlying BFD functionality supports it, you could use
19195@kbd{gdb -write} to patch object files using this technique. Note
19196that @value{GDBN} can neither interpret nor modify relocations in this
19197case, so branches and some initialized variables will appear to go to
19198the wrong place. But this feature is still handy from time to time.
19199
c906108c
SS
19200@item file
19201@code{file} with no argument makes @value{GDBN} discard any information it
19202has on both executable file and the symbol table.
19203
19204@kindex exec-file
19205@item exec-file @r{[} @var{filename} @r{]}
19206Specify that the program to be run (but not the symbol table) is found
19207in @var{filename}. @value{GDBN} searches the environment variable @code{PATH}
19208if necessary to locate your program. Omitting @var{filename} means to
19209discard information on the executable file.
19210
19211@kindex symbol-file
d4d429d5 19212@item symbol-file @r{[} @var{filename} @r{[} -o @var{offset} @r{]]}
c906108c
SS
19213Read symbol table information from file @var{filename}. @code{PATH} is
19214searched when necessary. Use the @code{file} command to get both symbol
19215table and program to run from the same file.
19216
d4d429d5
PT
19217If an optional @var{offset} is specified, it is added to the start
19218address of each section in the symbol file. This is useful if the
19219program is relocated at runtime, such as the Linux kernel with kASLR
19220enabled.
19221
c906108c
SS
19222@code{symbol-file} with no argument clears out @value{GDBN} information on your
19223program's symbol table.
19224
ae5a43e0
DJ
19225The @code{symbol-file} command causes @value{GDBN} to forget the contents of
19226some breakpoints and auto-display expressions. This is because they may
19227contain pointers to the internal data recording symbols and data types,
19228which are part of the old symbol table data being discarded inside
19229@value{GDBN}.
c906108c
SS
19230
19231@code{symbol-file} does not repeat if you press @key{RET} again after
19232executing it once.
19233
19234When @value{GDBN} is configured for a particular environment, it
19235understands debugging information in whatever format is the standard
19236generated for that environment; you may use either a @sc{gnu} compiler, or
19237other compilers that adhere to the local conventions.
c906108c 19238Best results are usually obtained from @sc{gnu} compilers; for example,
e22ea452 19239using @code{@value{NGCC}} you can generate debugging information for
c906108c 19240optimized code.
c906108c
SS
19241
19242For most kinds of object files, with the exception of old SVR3 systems
19243using COFF, the @code{symbol-file} command does not normally read the
19244symbol table in full right away. Instead, it scans the symbol table
19245quickly to find which source files and which symbols are present. The
19246details are read later, one source file at a time, as they are needed.
19247
19248The purpose of this two-stage reading strategy is to make @value{GDBN}
19249start up faster. For the most part, it is invisible except for
19250occasional pauses while the symbol table details for a particular source
19251file are being read. (The @code{set verbose} command can turn these
19252pauses into messages if desired. @xref{Messages/Warnings, ,Optional
79a6e687 19253Warnings and Messages}.)
c906108c 19254
c906108c
SS
19255We have not implemented the two-stage strategy for COFF yet. When the
19256symbol table is stored in COFF format, @code{symbol-file} reads the
19257symbol table data in full right away. Note that ``stabs-in-COFF''
19258still does the two-stage strategy, since the debug info is actually
19259in stabs format.
19260
19261@kindex readnow
19262@cindex reading symbols immediately
19263@cindex symbols, reading immediately
6ac33a4e
TT
19264@item symbol-file @r{[} -readnow @r{]} @var{filename}
19265@itemx file @r{[} -readnow @r{]} @var{filename}
c906108c
SS
19266You can override the @value{GDBN} two-stage strategy for reading symbol
19267tables by using the @samp{-readnow} option with any of the commands that
19268load symbol table information, if you want to be sure @value{GDBN} has the
5d161b24 19269entire symbol table available.
c906108c 19270
97cbe998
SDJ
19271@cindex @code{-readnever}, option for symbol-file command
19272@cindex never read symbols
19273@cindex symbols, never read
19274@item symbol-file @r{[} -readnever @r{]} @var{filename}
19275@itemx file @r{[} -readnever @r{]} @var{filename}
19276You can instruct @value{GDBN} to never read the symbolic information
19277contained in @var{filename} by using the @samp{-readnever} option.
19278@xref{--readnever}.
19279
c906108c
SS
19280@c FIXME: for now no mention of directories, since this seems to be in
19281@c flux. 13mar1992 status is that in theory GDB would look either in
19282@c current dir or in same dir as myprog; but issues like competing
19283@c GDB's, or clutter in system dirs, mean that in practice right now
19284@c only current dir is used. FFish says maybe a special GDB hierarchy
19285@c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol
19286@c files.
19287
c906108c 19288@kindex core-file
09d4efe1 19289@item core-file @r{[}@var{filename}@r{]}
4644b6e3 19290@itemx core
c906108c
SS
19291Specify the whereabouts of a core dump file to be used as the ``contents
19292of memory''. Traditionally, core files contain only some parts of the
19293address space of the process that generated them; @value{GDBN} can access the
19294executable file itself for other parts.
19295
19296@code{core-file} with no argument specifies that no core file is
19297to be used.
19298
19299Note that the core file is ignored when your program is actually running
7a292a7a
SS
19300under @value{GDBN}. So, if you have been running your program and you
19301wish to debug a core file instead, you must kill the subprocess in which
19302the program is running. To do this, use the @code{kill} command
79a6e687 19303(@pxref{Kill Process, ,Killing the Child Process}).
c906108c 19304
c906108c
SS
19305@kindex add-symbol-file
19306@cindex dynamic linking
291f9a96 19307@item add-symbol-file @var{filename} @r{[} -readnow @r{|} -readnever @r{]} @r{[} -o @var{offset} @r{]} @r{[} @var{textaddress} @r{]} @r{[} -s @var{section} @var{address} @dots{} @r{]}
96a2c332
SS
19308The @code{add-symbol-file} command reads additional symbol table
19309information from the file @var{filename}. You would use this command
19310when @var{filename} has been dynamically loaded (by some other means)
ed6dfe51
PT
19311into the program that is running. The @var{textaddress} parameter gives
19312the memory address at which the file's text section has been loaded.
19313You can additionally specify the base address of other sections using
19314an arbitrary number of @samp{-s @var{section} @var{address}} pairs.
19315If a section is omitted, @value{GDBN} will use its default addresses
19316as found in @var{filename}. Any @var{address} or @var{textaddress}
19317can be given as an expression.
c906108c 19318
291f9a96
PT
19319If an optional @var{offset} is specified, it is added to the start
19320address of each section, except those for which the address was
19321specified explicitly.
19322
c906108c
SS
19323The symbol table of the file @var{filename} is added to the symbol table
19324originally read with the @code{symbol-file} command. You can use the
96a2c332 19325@code{add-symbol-file} command any number of times; the new symbol data
98297bf6
NB
19326thus read is kept in addition to the old.
19327
19328Changes can be reverted using the command @code{remove-symbol-file}.
c906108c 19329
17d9d558
JB
19330@cindex relocatable object files, reading symbols from
19331@cindex object files, relocatable, reading symbols from
19332@cindex reading symbols from relocatable object files
19333@cindex symbols, reading from relocatable object files
19334@cindex @file{.o} files, reading symbols from
19335Although @var{filename} is typically a shared library file, an
19336executable file, or some other object file which has been fully
19337relocated for loading into a process, you can also load symbolic
19338information from relocatable @file{.o} files, as long as:
19339
19340@itemize @bullet
19341@item
19342the file's symbolic information refers only to linker symbols defined in
19343that file, not to symbols defined by other object files,
19344@item
19345every section the file's symbolic information refers to has actually
19346been loaded into the inferior, as it appears in the file, and
19347@item
19348you can determine the address at which every section was loaded, and
19349provide these to the @code{add-symbol-file} command.
19350@end itemize
19351
19352@noindent
19353Some embedded operating systems, like Sun Chorus and VxWorks, can load
19354relocatable files into an already running program; such systems
19355typically make the requirements above easy to meet. However, it's
19356important to recognize that many native systems use complex link
49efadf5 19357procedures (@code{.linkonce} section factoring and C@t{++} constructor table
17d9d558
JB
19358assembly, for example) that make the requirements difficult to meet. In
19359general, one cannot assume that using @code{add-symbol-file} to read a
19360relocatable object file's symbolic information will have the same effect
19361as linking the relocatable object file into the program in the normal
19362way.
19363
c906108c
SS
19364@code{add-symbol-file} does not repeat if you press @key{RET} after using it.
19365
98297bf6
NB
19366@kindex remove-symbol-file
19367@item remove-symbol-file @var{filename}
19368@item remove-symbol-file -a @var{address}
19369Remove a symbol file added via the @code{add-symbol-file} command. The
19370file to remove can be identified by its @var{filename} or by an @var{address}
19371that lies within the boundaries of this symbol file in memory. Example:
19372
19373@smallexample
19374(gdb) add-symbol-file /home/user/gdb/mylib.so 0x7ffff7ff9480
19375add symbol table from file "/home/user/gdb/mylib.so" at
19376 .text_addr = 0x7ffff7ff9480
19377(y or n) y
19378Reading symbols from /home/user/gdb/mylib.so...done.
19379(gdb) remove-symbol-file -a 0x7ffff7ff9480
19380Remove symbol table from file "/home/user/gdb/mylib.so"? (y or n) y
19381(gdb)
19382@end smallexample
19383
19384
19385@code{remove-symbol-file} does not repeat if you press @key{RET} after using it.
19386
c45da7e6
EZ
19387@kindex add-symbol-file-from-memory
19388@cindex @code{syscall DSO}
19389@cindex load symbols from memory
19390@item add-symbol-file-from-memory @var{address}
19391Load symbols from the given @var{address} in a dynamically loaded
19392object file whose image is mapped directly into the inferior's memory.
19393For example, the Linux kernel maps a @code{syscall DSO} into each
19394process's address space; this DSO provides kernel-specific code for
19395some system calls. The argument can be any expression whose
19396evaluation yields the address of the file's shared object file header.
19397For this command to work, you must have used @code{symbol-file} or
19398@code{exec-file} commands in advance.
19399
c906108c 19400@kindex section
09d4efe1
EZ
19401@item section @var{section} @var{addr}
19402The @code{section} command changes the base address of the named
19403@var{section} of the exec file to @var{addr}. This can be used if the
19404exec file does not contain section addresses, (such as in the
19405@code{a.out} format), or when the addresses specified in the file
19406itself are wrong. Each section must be changed separately. The
19407@code{info files} command, described below, lists all the sections and
19408their addresses.
c906108c
SS
19409
19410@kindex info files
19411@kindex info target
19412@item info files
19413@itemx info target
7a292a7a
SS
19414@code{info files} and @code{info target} are synonymous; both print the
19415current target (@pxref{Targets, ,Specifying a Debugging Target}),
19416including the names of the executable and core dump files currently in
19417use by @value{GDBN}, and the files from which symbols were loaded. The
19418command @code{help target} lists all possible targets rather than
19419current ones.
19420
fe95c787
MS
19421@kindex maint info sections
19422@item maint info sections
19423Another command that can give you extra information about program sections
19424is @code{maint info sections}. In addition to the section information
19425displayed by @code{info files}, this command displays the flags and file
19426offset of each section in the executable and core dump files. In addition,
19427@code{maint info sections} provides the following command options (which
19428may be arbitrarily combined):
19429
19430@table @code
19431@item ALLOBJ
19432Display sections for all loaded object files, including shared libraries.
19433@item @var{sections}
6600abed 19434Display info only for named @var{sections}.
fe95c787
MS
19435@item @var{section-flags}
19436Display info only for sections for which @var{section-flags} are true.
19437The section flags that @value{GDBN} currently knows about are:
19438@table @code
19439@item ALLOC
19440Section will have space allocated in the process when loaded.
19441Set for all sections except those containing debug information.
19442@item LOAD
19443Section will be loaded from the file into the child process memory.
19444Set for pre-initialized code and data, clear for @code{.bss} sections.
19445@item RELOC
19446Section needs to be relocated before loading.
19447@item READONLY
19448Section cannot be modified by the child process.
19449@item CODE
19450Section contains executable code only.
6600abed 19451@item DATA
fe95c787
MS
19452Section contains data only (no executable code).
19453@item ROM
19454Section will reside in ROM.
19455@item CONSTRUCTOR
19456Section contains data for constructor/destructor lists.
19457@item HAS_CONTENTS
19458Section is not empty.
19459@item NEVER_LOAD
19460An instruction to the linker to not output the section.
19461@item COFF_SHARED_LIBRARY
19462A notification to the linker that the section contains
19463COFF shared library information.
19464@item IS_COMMON
19465Section contains common symbols.
19466@end table
19467@end table
6763aef9 19468@kindex set trust-readonly-sections
9c16f35a 19469@cindex read-only sections
6763aef9
MS
19470@item set trust-readonly-sections on
19471Tell @value{GDBN} that readonly sections in your object file
6ca652b0 19472really are read-only (i.e.@: that their contents will not change).
6763aef9
MS
19473In that case, @value{GDBN} can fetch values from these sections
19474out of the object file, rather than from the target program.
19475For some targets (notably embedded ones), this can be a significant
19476enhancement to debugging performance.
19477
19478The default is off.
19479
19480@item set trust-readonly-sections off
15110bc3 19481Tell @value{GDBN} not to trust readonly sections. This means that
6763aef9
MS
19482the contents of the section might change while the program is running,
19483and must therefore be fetched from the target when needed.
9c16f35a
EZ
19484
19485@item show trust-readonly-sections
19486Show the current setting of trusting readonly sections.
c906108c
SS
19487@end table
19488
19489All file-specifying commands allow both absolute and relative file names
19490as arguments. @value{GDBN} always converts the file name to an absolute file
19491name and remembers it that way.
19492
c906108c 19493@cindex shared libraries
9cceb671 19494@anchor{Shared Libraries}
b1236ac3
PA
19495@value{GDBN} supports @sc{gnu}/Linux, MS-Windows, SunOS,
19496Darwin/Mach-O, SVr4, IBM RS/6000 AIX, QNX Neutrino, FDPIC (FR-V), and
19497DSBT (TIC6X) shared libraries.
53a5351d 19498
9cceb671
DJ
19499On MS-Windows @value{GDBN} must be linked with the Expat library to support
19500shared libraries. @xref{Expat}.
19501
c906108c
SS
19502@value{GDBN} automatically loads symbol definitions from shared libraries
19503when you use the @code{run} command, or when you examine a core file.
19504(Before you issue the @code{run} command, @value{GDBN} does not understand
19505references to a function in a shared library, however---unless you are
19506debugging a core file).
53a5351d 19507
c906108c
SS
19508@c FIXME: some @value{GDBN} release may permit some refs to undef
19509@c FIXME...symbols---eg in a break cmd---assuming they are from a shared
19510@c FIXME...lib; check this from time to time when updating manual
19511
b7209cb4
FF
19512There are times, however, when you may wish to not automatically load
19513symbol definitions from shared libraries, such as when they are
19514particularly large or there are many of them.
19515
19516To control the automatic loading of shared library symbols, use the
19517commands:
19518
19519@table @code
19520@kindex set auto-solib-add
19521@item set auto-solib-add @var{mode}
19522If @var{mode} is @code{on}, symbols from all shared object libraries
19523will be loaded automatically when the inferior begins execution, you
19524attach to an independently started inferior, or when the dynamic linker
19525informs @value{GDBN} that a new library has been loaded. If @var{mode}
19526is @code{off}, symbols must be loaded manually, using the
19527@code{sharedlibrary} command. The default value is @code{on}.
19528
dcaf7c2c
EZ
19529@cindex memory used for symbol tables
19530If your program uses lots of shared libraries with debug info that
19531takes large amounts of memory, you can decrease the @value{GDBN}
19532memory footprint by preventing it from automatically loading the
19533symbols from shared libraries. To that end, type @kbd{set
19534auto-solib-add off} before running the inferior, then load each
19535library whose debug symbols you do need with @kbd{sharedlibrary
d3e8051b 19536@var{regexp}}, where @var{regexp} is a regular expression that matches
dcaf7c2c
EZ
19537the libraries whose symbols you want to be loaded.
19538
b7209cb4
FF
19539@kindex show auto-solib-add
19540@item show auto-solib-add
19541Display the current autoloading mode.
19542@end table
19543
c45da7e6 19544@cindex load shared library
b7209cb4
FF
19545To explicitly load shared library symbols, use the @code{sharedlibrary}
19546command:
19547
c906108c
SS
19548@table @code
19549@kindex info sharedlibrary
19550@kindex info share
55333a84
DE
19551@item info share @var{regex}
19552@itemx info sharedlibrary @var{regex}
19553Print the names of the shared libraries which are currently loaded
19554that match @var{regex}. If @var{regex} is omitted then print
19555all shared libraries that are loaded.
c906108c 19556
b30a0bc3
JB
19557@kindex info dll
19558@item info dll @var{regex}
19559This is an alias of @code{info sharedlibrary}.
19560
c906108c
SS
19561@kindex sharedlibrary
19562@kindex share
19563@item sharedlibrary @var{regex}
19564@itemx share @var{regex}
c906108c
SS
19565Load shared object library symbols for files matching a
19566Unix regular expression.
19567As with files loaded automatically, it only loads shared libraries
19568required by your program for a core file or after typing @code{run}. If
19569@var{regex} is omitted all shared libraries required by your program are
19570loaded.
c45da7e6
EZ
19571
19572@item nosharedlibrary
19573@kindex nosharedlibrary
19574@cindex unload symbols from shared libraries
19575Unload all shared object library symbols. This discards all symbols
19576that have been loaded from all shared libraries. Symbols from shared
19577libraries that were loaded by explicit user requests are not
19578discarded.
c906108c
SS
19579@end table
19580
721c2651 19581Sometimes you may wish that @value{GDBN} stops and gives you control
edcc5120
TT
19582when any of shared library events happen. The best way to do this is
19583to use @code{catch load} and @code{catch unload} (@pxref{Set
19584Catchpoints}).
19585
19586@value{GDBN} also supports the the @code{set stop-on-solib-events}
19587command for this. This command exists for historical reasons. It is
19588less useful than setting a catchpoint, because it does not allow for
19589conditions or commands as a catchpoint does.
721c2651
EZ
19590
19591@table @code
19592@item set stop-on-solib-events
19593@kindex set stop-on-solib-events
19594This command controls whether @value{GDBN} should give you control
19595when the dynamic linker notifies it about some shared library event.
19596The most common event of interest is loading or unloading of a new
19597shared library.
19598
19599@item show stop-on-solib-events
19600@kindex show stop-on-solib-events
19601Show whether @value{GDBN} stops and gives you control when shared
19602library events happen.
19603@end table
19604
f5ebfba0 19605Shared libraries are also supported in many cross or remote debugging
f1838a98
UW
19606configurations. @value{GDBN} needs to have access to the target's libraries;
19607this can be accomplished either by providing copies of the libraries
19608on the host system, or by asking @value{GDBN} to automatically retrieve the
19609libraries from the target. If copies of the target libraries are
19610provided, they need to be the same as the target libraries, although the
f5ebfba0
DJ
19611copies on the target can be stripped as long as the copies on the host are
19612not.
19613
59b7b46f
EZ
19614@cindex where to look for shared libraries
19615For remote debugging, you need to tell @value{GDBN} where the target
19616libraries are, so that it can load the correct copies---otherwise, it
19617may try to load the host's libraries. @value{GDBN} has two variables
19618to specify the search directories for target libraries.
f5ebfba0
DJ
19619
19620@table @code
a9a5a3d1 19621@cindex prefix for executable and shared library file names
f822c95b 19622@cindex system root, alternate
f5ebfba0 19623@kindex set solib-absolute-prefix
f822c95b
DJ
19624@kindex set sysroot
19625@item set sysroot @var{path}
19626Use @var{path} as the system root for the program being debugged. Any
19627absolute shared library paths will be prefixed with @var{path}; many
19628runtime loaders store the absolute paths to the shared library in the
a9a5a3d1
GB
19629target program's memory. When starting processes remotely, and when
19630attaching to already-running processes (local or remote), their
19631executable filenames will be prefixed with @var{path} if reported to
19632@value{GDBN} as absolute by the operating system. If you use
19633@code{set sysroot} to find executables and shared libraries, they need
19634to be laid out in the same way that they are on the target, with
19635e.g.@: a @file{/bin}, @file{/lib} and @file{/usr/lib} hierarchy under
19636@var{path}.
f822c95b 19637
599bd15c
GB
19638If @var{path} starts with the sequence @file{target:} and the target
19639system is remote then @value{GDBN} will retrieve the target binaries
19640from the remote system. This is only supported when using a remote
19641target that supports the @code{remote get} command (@pxref{File
19642Transfer,,Sending files to a remote system}). The part of @var{path}
19643following the initial @file{target:} (if present) is used as system
19644root prefix on the remote file system. If @var{path} starts with the
19645sequence @file{remote:} this is converted to the sequence
19646@file{target:} by @code{set sysroot}@footnote{Historically the
19647functionality to retrieve binaries from the remote system was
19648provided by prefixing @var{path} with @file{remote:}}. If you want
19649to specify a local system root using a directory that happens to be
19650named @file{target:} or @file{remote:}, you need to use some
19651equivalent variant of the name like @file{./target:}.
f1838a98 19652
ab38a727
PA
19653For targets with an MS-DOS based filesystem, such as MS-Windows and
19654SymbianOS, @value{GDBN} tries prefixing a few variants of the target
19655absolute file name with @var{path}. But first, on Unix hosts,
19656@value{GDBN} converts all backslash directory separators into forward
19657slashes, because the backslash is not a directory separator on Unix:
19658
19659@smallexample
19660 c:\foo\bar.dll @result{} c:/foo/bar.dll
19661@end smallexample
19662
19663Then, @value{GDBN} attempts prefixing the target file name with
19664@var{path}, and looks for the resulting file name in the host file
19665system:
19666
19667@smallexample
19668 c:/foo/bar.dll @result{} /path/to/sysroot/c:/foo/bar.dll
19669@end smallexample
19670
a9a5a3d1 19671If that does not find the binary, @value{GDBN} tries removing
ab38a727
PA
19672the @samp{:} character from the drive spec, both for convenience, and,
19673for the case of the host file system not supporting file names with
19674colons:
19675
19676@smallexample
19677 c:/foo/bar.dll @result{} /path/to/sysroot/c/foo/bar.dll
19678@end smallexample
19679
19680This makes it possible to have a system root that mirrors a target
19681with more than one drive. E.g., you may want to setup your local
19682copies of the target system shared libraries like so (note @samp{c} vs
19683@samp{z}):
19684
19685@smallexample
19686 @file{/path/to/sysroot/c/sys/bin/foo.dll}
19687 @file{/path/to/sysroot/c/sys/bin/bar.dll}
19688 @file{/path/to/sysroot/z/sys/bin/bar.dll}
19689@end smallexample
19690
19691@noindent
19692and point the system root at @file{/path/to/sysroot}, so that
19693@value{GDBN} can find the correct copies of both
19694@file{c:\sys\bin\foo.dll}, and @file{z:\sys\bin\bar.dll}.
19695
a9a5a3d1 19696If that still does not find the binary, @value{GDBN} tries
ab38a727
PA
19697removing the whole drive spec from the target file name:
19698
19699@smallexample
19700 c:/foo/bar.dll @result{} /path/to/sysroot/foo/bar.dll
19701@end smallexample
19702
19703This last lookup makes it possible to not care about the drive name,
19704if you don't want or need to.
19705
f822c95b
DJ
19706The @code{set solib-absolute-prefix} command is an alias for @code{set
19707sysroot}.
19708
19709@cindex default system root
59b7b46f 19710@cindex @samp{--with-sysroot}
f822c95b
DJ
19711You can set the default system root by using the configure-time
19712@samp{--with-sysroot} option. If the system root is inside
19713@value{GDBN}'s configured binary prefix (set with @samp{--prefix} or
19714@samp{--exec-prefix}), then the default system root will be updated
19715automatically if the installed @value{GDBN} is moved to a new
19716location.
19717
19718@kindex show sysroot
19719@item show sysroot
a9a5a3d1 19720Display the current executable and shared library prefix.
f5ebfba0
DJ
19721
19722@kindex set solib-search-path
19723@item set solib-search-path @var{path}
f822c95b
DJ
19724If this variable is set, @var{path} is a colon-separated list of
19725directories to search for shared libraries. @samp{solib-search-path}
19726is used after @samp{sysroot} fails to locate the library, or if the
19727path to the library is relative instead of absolute. If you want to
19728use @samp{solib-search-path} instead of @samp{sysroot}, be sure to set
d3e8051b 19729@samp{sysroot} to a nonexistent directory to prevent @value{GDBN} from
f822c95b 19730finding your host's libraries. @samp{sysroot} is preferred; setting
d3e8051b 19731it to a nonexistent directory may interfere with automatic loading
f822c95b 19732of shared library symbols.
f5ebfba0
DJ
19733
19734@kindex show solib-search-path
19735@item show solib-search-path
19736Display the current shared library search path.
ab38a727
PA
19737
19738@cindex DOS file-name semantics of file names.
19739@kindex set target-file-system-kind (unix|dos-based|auto)
19740@kindex show target-file-system-kind
19741@item set target-file-system-kind @var{kind}
19742Set assumed file system kind for target reported file names.
19743
19744Shared library file names as reported by the target system may not
19745make sense as is on the system @value{GDBN} is running on. For
19746example, when remote debugging a target that has MS-DOS based file
19747system semantics, from a Unix host, the target may be reporting to
19748@value{GDBN} a list of loaded shared libraries with file names such as
19749@file{c:\Windows\kernel32.dll}. On Unix hosts, there's no concept of
19750drive letters, so the @samp{c:\} prefix is not normally understood as
19751indicating an absolute file name, and neither is the backslash
19752normally considered a directory separator character. In that case,
19753the native file system would interpret this whole absolute file name
19754as a relative file name with no directory components. This would make
19755it impossible to point @value{GDBN} at a copy of the remote target's
19756shared libraries on the host using @code{set sysroot}, and impractical
19757with @code{set solib-search-path}. Setting
19758@code{target-file-system-kind} to @code{dos-based} tells @value{GDBN}
19759to interpret such file names similarly to how the target would, and to
19760map them to file names valid on @value{GDBN}'s native file system
19761semantics. The value of @var{kind} can be @code{"auto"}, in addition
19762to one of the supported file system kinds. In that case, @value{GDBN}
19763tries to determine the appropriate file system variant based on the
19764current target's operating system (@pxref{ABI, ,Configuring the
19765Current ABI}). The supported file system settings are:
19766
19767@table @code
19768@item unix
19769Instruct @value{GDBN} to assume the target file system is of Unix
19770kind. Only file names starting the forward slash (@samp{/}) character
19771are considered absolute, and the directory separator character is also
19772the forward slash.
19773
19774@item dos-based
19775Instruct @value{GDBN} to assume the target file system is DOS based.
19776File names starting with either a forward slash, or a drive letter
19777followed by a colon (e.g., @samp{c:}), are considered absolute, and
19778both the slash (@samp{/}) and the backslash (@samp{\\}) characters are
19779considered directory separators.
19780
19781@item auto
19782Instruct @value{GDBN} to use the file system kind associated with the
19783target operating system (@pxref{ABI, ,Configuring the Current ABI}).
19784This is the default.
19785@end table
f5ebfba0
DJ
19786@end table
19787
c011a4f4
DE
19788@cindex file name canonicalization
19789@cindex base name differences
19790When processing file names provided by the user, @value{GDBN}
19791frequently needs to compare them to the file names recorded in the
19792program's debug info. Normally, @value{GDBN} compares just the
19793@dfn{base names} of the files as strings, which is reasonably fast
19794even for very large programs. (The base name of a file is the last
19795portion of its name, after stripping all the leading directories.)
19796This shortcut in comparison is based upon the assumption that files
19797cannot have more than one base name. This is usually true, but
19798references to files that use symlinks or similar filesystem
19799facilities violate that assumption. If your program records files
19800using such facilities, or if you provide file names to @value{GDBN}
19801using symlinks etc., you can set @code{basenames-may-differ} to
19802@code{true} to instruct @value{GDBN} to completely canonicalize each
19803pair of file names it needs to compare. This will make file-name
19804comparisons accurate, but at a price of a significant slowdown.
19805
19806@table @code
19807@item set basenames-may-differ
19808@kindex set basenames-may-differ
19809Set whether a source file may have multiple base names.
19810
19811@item show basenames-may-differ
19812@kindex show basenames-may-differ
19813Show whether a source file may have multiple base names.
19814@end table
5b5d99cf 19815
18989b3c
AB
19816@node File Caching
19817@section File Caching
19818@cindex caching of opened files
19819@cindex caching of bfd objects
19820
19821To speed up file loading, and reduce memory usage, @value{GDBN} will
19822reuse the @code{bfd} objects used to track open files. @xref{Top, ,
19823BFD, bfd, The Binary File Descriptor Library}. The following commands
19824allow visibility and control of the caching behavior.
19825
19826@table @code
19827@kindex maint info bfds
19828@item maint info bfds
19829This prints information about each @code{bfd} object that is known to
19830@value{GDBN}.
19831
19832@kindex maint set bfd-sharing
19833@kindex maint show bfd-sharing
19834@kindex bfd caching
19835@item maint set bfd-sharing
19836@item maint show bfd-sharing
19837Control whether @code{bfd} objects can be shared. When sharing is
19838enabled @value{GDBN} reuses already open @code{bfd} objects rather
19839than reopening the same file. Turning sharing off does not cause
19840already shared @code{bfd} objects to be unshared, but all future files
19841that are opened will create a new @code{bfd} object. Similarly,
19842re-enabling sharing does not cause multiple existing @code{bfd}
19843objects to be collapsed into a single shared @code{bfd} object.
566f5e3b
AB
19844
19845@kindex set debug bfd-cache @var{level}
19846@kindex bfd caching
19847@item set debug bfd-cache @var{level}
19848Turns on debugging of the bfd cache, setting the level to @var{level}.
19849
19850@kindex show debug bfd-cache
19851@kindex bfd caching
19852@item show debug bfd-cache
19853Show the current debugging level of the bfd cache.
18989b3c
AB
19854@end table
19855
5b5d99cf
JB
19856@node Separate Debug Files
19857@section Debugging Information in Separate Files
19858@cindex separate debugging information files
19859@cindex debugging information in separate files
19860@cindex @file{.debug} subdirectories
19861@cindex debugging information directory, global
f307c045 19862@cindex global debugging information directories
c7e83d54
EZ
19863@cindex build ID, and separate debugging files
19864@cindex @file{.build-id} directory
5b5d99cf
JB
19865
19866@value{GDBN} allows you to put a program's debugging information in a
19867file separate from the executable itself, in a way that allows
19868@value{GDBN} to find and load the debugging information automatically.
c7e83d54
EZ
19869Since debugging information can be very large---sometimes larger
19870than the executable code itself---some systems distribute debugging
5b5d99cf
JB
19871information for their executables in separate files, which users can
19872install only when they need to debug a problem.
19873
c7e83d54
EZ
19874@value{GDBN} supports two ways of specifying the separate debug info
19875file:
5b5d99cf
JB
19876
19877@itemize @bullet
19878@item
c7e83d54
EZ
19879The executable contains a @dfn{debug link} that specifies the name of
19880the separate debug info file. The separate debug file's name is
19881usually @file{@var{executable}.debug}, where @var{executable} is the
19882name of the corresponding executable file without leading directories
19883(e.g., @file{ls.debug} for @file{/usr/bin/ls}). In addition, the
99e008fe
EZ
19884debug link specifies a 32-bit @dfn{Cyclic Redundancy Check} (CRC)
19885checksum for the debug file, which @value{GDBN} uses to validate that
19886the executable and the debug file came from the same build.
c7e83d54
EZ
19887
19888@item
7e27a47a 19889The executable contains a @dfn{build ID}, a unique bit string that is
c7e83d54 19890also present in the corresponding debug info file. (This is supported
c74f7d1c 19891only on some operating systems, when using the ELF or PE file formats
7e27a47a
EZ
19892for binary files and the @sc{gnu} Binutils.) For more details about
19893this feature, see the description of the @option{--build-id}
f5a476a7 19894command-line option in @ref{Options, , Command Line Options, ld,
7e27a47a
EZ
19895The GNU Linker}. The debug info file's name is not specified
19896explicitly by the build ID, but can be computed from the build ID, see
19897below.
d3750b24
JK
19898@end itemize
19899
c7e83d54
EZ
19900Depending on the way the debug info file is specified, @value{GDBN}
19901uses two different methods of looking for the debug file:
d3750b24
JK
19902
19903@itemize @bullet
19904@item
c7e83d54
EZ
19905For the ``debug link'' method, @value{GDBN} looks up the named file in
19906the directory of the executable file, then in a subdirectory of that
f307c045
JK
19907directory named @file{.debug}, and finally under each one of the global debug
19908directories, in a subdirectory whose name is identical to the leading
c7e83d54
EZ
19909directories of the executable's absolute file name.
19910
19911@item
83f83d7f 19912For the ``build ID'' method, @value{GDBN} looks in the
f307c045
JK
19913@file{.build-id} subdirectory of each one of the global debug directories for
19914a file named @file{@var{nn}/@var{nnnnnnnn}.debug}, where @var{nn} are the
7e27a47a
EZ
19915first 2 hex characters of the build ID bit string, and @var{nnnnnnnn}
19916are the rest of the bit string. (Real build ID strings are 32 or more
19917hex characters, not 10.)
c7e83d54
EZ
19918@end itemize
19919
19920So, for example, suppose you ask @value{GDBN} to debug
7e27a47a
EZ
19921@file{/usr/bin/ls}, which has a debug link that specifies the
19922file @file{ls.debug}, and a build ID whose value in hex is
f307c045 19923@code{abcdef1234}. If the list of the global debug directories includes
c7e83d54
EZ
19924@file{/usr/lib/debug}, then @value{GDBN} will look for the following
19925debug information files, in the indicated order:
19926
19927@itemize @minus
19928@item
19929@file{/usr/lib/debug/.build-id/ab/cdef1234.debug}
d3750b24 19930@item
c7e83d54 19931@file{/usr/bin/ls.debug}
5b5d99cf 19932@item
c7e83d54 19933@file{/usr/bin/.debug/ls.debug}
5b5d99cf 19934@item
c7e83d54 19935@file{/usr/lib/debug/usr/bin/ls.debug}.
5b5d99cf 19936@end itemize
5b5d99cf 19937
1564a261
JK
19938@anchor{debug-file-directory}
19939Global debugging info directories default to what is set by @value{GDBN}
19940configure option @option{--with-separate-debug-dir}. During @value{GDBN} run
19941you can also set the global debugging info directories, and view the list
19942@value{GDBN} is currently using.
5b5d99cf
JB
19943
19944@table @code
19945
19946@kindex set debug-file-directory
24ddea62
JK
19947@item set debug-file-directory @var{directories}
19948Set the directories which @value{GDBN} searches for separate debugging
d9242c17
JK
19949information files to @var{directory}. Multiple path components can be set
19950concatenating them by a path separator.
5b5d99cf
JB
19951
19952@kindex show debug-file-directory
19953@item show debug-file-directory
24ddea62 19954Show the directories @value{GDBN} searches for separate debugging
5b5d99cf
JB
19955information files.
19956
19957@end table
19958
19959@cindex @code{.gnu_debuglink} sections
c7e83d54 19960@cindex debug link sections
5b5d99cf
JB
19961A debug link is a special section of the executable file named
19962@code{.gnu_debuglink}. The section must contain:
19963
19964@itemize
19965@item
19966A filename, with any leading directory components removed, followed by
19967a zero byte,
19968@item
19969zero to three bytes of padding, as needed to reach the next four-byte
19970boundary within the section, and
19971@item
19972a four-byte CRC checksum, stored in the same endianness used for the
19973executable file itself. The checksum is computed on the debugging
19974information file's full contents by the function given below, passing
19975zero as the @var{crc} argument.
19976@end itemize
19977
19978Any executable file format can carry a debug link, as long as it can
19979contain a section named @code{.gnu_debuglink} with the contents
19980described above.
19981
d3750b24 19982@cindex @code{.note.gnu.build-id} sections
c7e83d54 19983@cindex build ID sections
7e27a47a
EZ
19984The build ID is a special section in the executable file (and in other
19985ELF binary files that @value{GDBN} may consider). This section is
19986often named @code{.note.gnu.build-id}, but that name is not mandatory.
19987It contains unique identification for the built files---the ID remains
19988the same across multiple builds of the same build tree. The default
19989algorithm SHA1 produces 160 bits (40 hexadecimal characters) of the
19990content for the build ID string. The same section with an identical
19991value is present in the original built binary with symbols, in its
19992stripped variant, and in the separate debugging information file.
d3750b24 19993
5b5d99cf
JB
19994The debugging information file itself should be an ordinary
19995executable, containing a full set of linker symbols, sections, and
19996debugging information. The sections of the debugging information file
c7e83d54
EZ
19997should have the same names, addresses, and sizes as the original file,
19998but they need not contain any data---much like a @code{.bss} section
5b5d99cf
JB
19999in an ordinary executable.
20000
7e27a47a 20001The @sc{gnu} binary utilities (Binutils) package includes the
c7e83d54
EZ
20002@samp{objcopy} utility that can produce
20003the separated executable / debugging information file pairs using the
20004following commands:
20005
20006@smallexample
20007@kbd{objcopy --only-keep-debug foo foo.debug}
20008@kbd{strip -g foo}
c7e83d54
EZ
20009@end smallexample
20010
20011@noindent
20012These commands remove the debugging
83f83d7f
JK
20013information from the executable file @file{foo} and place it in the file
20014@file{foo.debug}. You can use the first, second or both methods to link the
20015two files:
20016
20017@itemize @bullet
20018@item
20019The debug link method needs the following additional command to also leave
20020behind a debug link in @file{foo}:
20021
20022@smallexample
20023@kbd{objcopy --add-gnu-debuglink=foo.debug foo}
20024@end smallexample
20025
20026Ulrich Drepper's @file{elfutils} package, starting with version 0.53, contains
d3750b24 20027a version of the @code{strip} command such that the command @kbd{strip foo -f
83f83d7f
JK
20028foo.debug} has the same functionality as the two @code{objcopy} commands and
20029the @code{ln -s} command above, together.
20030
20031@item
20032Build ID gets embedded into the main executable using @code{ld --build-id} or
20033the @value{NGCC} counterpart @code{gcc -Wl,--build-id}. Build ID support plus
20034compatibility fixes for debug files separation are present in @sc{gnu} binary
7e27a47a 20035utilities (Binutils) package since version 2.18.
83f83d7f
JK
20036@end itemize
20037
20038@noindent
d3750b24 20039
99e008fe
EZ
20040@cindex CRC algorithm definition
20041The CRC used in @code{.gnu_debuglink} is the CRC-32 defined in
20042IEEE 802.3 using the polynomial:
20043
20044@c TexInfo requires naked braces for multi-digit exponents for Tex
20045@c output, but this causes HTML output to barf. HTML has to be set using
20046@c raw commands. So we end up having to specify this equation in 2
20047@c different ways!
20048@ifhtml
20049@display
20050@html
20051 <em>x</em><sup>32</sup> + <em>x</em><sup>26</sup> + <em>x</em><sup>23</sup> + <em>x</em><sup>22</sup> + <em>x</em><sup>16</sup> + <em>x</em><sup>12</sup> + <em>x</em><sup>11</sup>
20052 + <em>x</em><sup>10</sup> + <em>x</em><sup>8</sup> + <em>x</em><sup>7</sup> + <em>x</em><sup>5</sup> + <em>x</em><sup>4</sup> + <em>x</em><sup>2</sup> + <em>x</em> + 1
20053@end html
20054@end display
20055@end ifhtml
20056@ifnothtml
20057@display
20058 @math{x^{32} + x^{26} + x^{23} + x^{22} + x^{16} + x^{12} + x^{11}}
20059 @math{+ x^{10} + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1}
20060@end display
20061@end ifnothtml
20062
20063The function is computed byte at a time, taking the least
20064significant bit of each byte first. The initial pattern
20065@code{0xffffffff} is used, to ensure leading zeros affect the CRC and
20066the final result is inverted to ensure trailing zeros also affect the
20067CRC.
20068
20069@emph{Note:} This is the same CRC polynomial as used in handling the
936d2992
PA
20070@dfn{Remote Serial Protocol} @code{qCRC} packet (@pxref{qCRC packet}).
20071However in the case of the Remote Serial Protocol, the CRC is computed
20072@emph{most} significant bit first, and the result is not inverted, so
20073trailing zeros have no effect on the CRC value.
99e008fe
EZ
20074
20075To complete the description, we show below the code of the function
20076which produces the CRC used in @code{.gnu_debuglink}. Inverting the
20077initially supplied @code{crc} argument means that an initial call to
20078this function passing in zero will start computing the CRC using
20079@code{0xffffffff}.
5b5d99cf 20080
4644b6e3 20081@kindex gnu_debuglink_crc32
5b5d99cf
JB
20082@smallexample
20083unsigned long
20084gnu_debuglink_crc32 (unsigned long crc,
20085 unsigned char *buf, size_t len)
20086@{
20087 static const unsigned long crc32_table[256] =
20088 @{
20089 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
20090 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
20091 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
20092 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
20093 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
20094 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
20095 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
20096 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
20097 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
20098 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
20099 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
20100 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
20101 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
20102 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
20103 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
20104 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
20105 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
20106 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
20107 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
20108 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
20109 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
20110 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
20111 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
20112 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
20113 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
20114 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
20115 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
20116 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
20117 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
20118 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
20119 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
20120 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
20121 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
20122 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
20123 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
20124 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
20125 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
20126 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
20127 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
20128 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
20129 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
20130 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
20131 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
20132 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
20133 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
20134 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
20135 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
20136 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
20137 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
20138 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
20139 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
20140 0x2d02ef8d
20141 @};
20142 unsigned char *end;
20143
20144 crc = ~crc & 0xffffffff;
20145 for (end = buf + len; buf < end; ++buf)
20146 crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
e7a3abfc 20147 return ~crc & 0xffffffff;
5b5d99cf
JB
20148@}
20149@end smallexample
20150
c7e83d54
EZ
20151@noindent
20152This computation does not apply to the ``build ID'' method.
20153
608e2dbb
TT
20154@node MiniDebugInfo
20155@section Debugging information in a special section
20156@cindex separate debug sections
20157@cindex @samp{.gnu_debugdata} section
20158
20159Some systems ship pre-built executables and libraries that have a
20160special @samp{.gnu_debugdata} section. This feature is called
20161@dfn{MiniDebugInfo}. This section holds an LZMA-compressed object and
20162is used to supply extra symbols for backtraces.
20163
20164The intent of this section is to provide extra minimal debugging
20165information for use in simple backtraces. It is not intended to be a
20166replacement for full separate debugging information (@pxref{Separate
20167Debug Files}). The example below shows the intended use; however,
20168@value{GDBN} does not currently put restrictions on what sort of
20169debugging information might be included in the section.
20170
20171@value{GDBN} has support for this extension. If the section exists,
20172then it is used provided that no other source of debugging information
20173can be found, and that @value{GDBN} was configured with LZMA support.
20174
20175This section can be easily created using @command{objcopy} and other
20176standard utilities:
20177
20178@smallexample
20179# Extract the dynamic symbols from the main binary, there is no need
5423b017 20180# to also have these in the normal symbol table.
608e2dbb
TT
20181nm -D @var{binary} --format=posix --defined-only \
20182 | awk '@{ print $1 @}' | sort > dynsyms
20183
5423b017 20184# Extract all the text (i.e. function) symbols from the debuginfo.
1d236d23
JK
20185# (Note that we actually also accept "D" symbols, for the benefit
20186# of platforms like PowerPC64 that use function descriptors.)
608e2dbb 20187nm @var{binary} --format=posix --defined-only \
1d236d23 20188 | awk '@{ if ($2 == "T" || $2 == "t" || $2 == "D") print $1 @}' \
608e2dbb
TT
20189 | sort > funcsyms
20190
20191# Keep all the function symbols not already in the dynamic symbol
20192# table.
20193comm -13 dynsyms funcsyms > keep_symbols
20194
edf9f00c
JK
20195# Separate full debug info into debug binary.
20196objcopy --only-keep-debug @var{binary} debug
20197
608e2dbb
TT
20198# Copy the full debuginfo, keeping only a minimal set of symbols and
20199# removing some unnecessary sections.
20200objcopy -S --remove-section .gdb_index --remove-section .comment \
edf9f00c
JK
20201 --keep-symbols=keep_symbols debug mini_debuginfo
20202
20203# Drop the full debug info from the original binary.
20204strip --strip-all -R .comment @var{binary}
608e2dbb
TT
20205
20206# Inject the compressed data into the .gnu_debugdata section of the
20207# original binary.
20208xz mini_debuginfo
20209objcopy --add-section .gnu_debugdata=mini_debuginfo.xz @var{binary}
20210@end smallexample
5b5d99cf 20211
9291a0cd
TT
20212@node Index Files
20213@section Index Files Speed Up @value{GDBN}
20214@cindex index files
20215@cindex @samp{.gdb_index} section
20216
20217When @value{GDBN} finds a symbol file, it scans the symbols in the
20218file in order to construct an internal symbol table. This lets most
20219@value{GDBN} operations work quickly---at the cost of a delay early
20220on. For large programs, this delay can be quite lengthy, so
20221@value{GDBN} provides a way to build an index, which speeds up
20222startup.
20223
ba643918
SDJ
20224For convenience, @value{GDBN} comes with a program,
20225@command{gdb-add-index}, which can be used to add the index to a
20226symbol file. It takes the symbol file as its only argument:
20227
20228@smallexample
20229$ gdb-add-index symfile
20230@end smallexample
20231
20232@xref{gdb-add-index}.
20233
20234It is also possible to do the work manually. Here is what
20235@command{gdb-add-index} does behind the curtains.
20236
9291a0cd
TT
20237The index is stored as a section in the symbol file. @value{GDBN} can
20238write the index to a file, then you can put it into the symbol file
20239using @command{objcopy}.
20240
20241To create an index file, use the @code{save gdb-index} command:
20242
20243@table @code
437afbb8 20244@item save gdb-index [-dwarf-5] @var{directory}
9291a0cd 20245@kindex save gdb-index
437afbb8
JK
20246Create index files for all symbol files currently known by
20247@value{GDBN}. For each known @var{symbol-file}, this command by
20248default creates it produces a single file
20249@file{@var{symbol-file}.gdb-index}. If you invoke this command with
20250the @option{-dwarf-5} option, it produces 2 files:
20251@file{@var{symbol-file}.debug_names} and
20252@file{@var{symbol-file}.debug_str}. The files are created in the
20253given @var{directory}.
9291a0cd
TT
20254@end table
20255
20256Once you have created an index file you can merge it into your symbol
20257file, here named @file{symfile}, using @command{objcopy}:
20258
20259@smallexample
20260$ objcopy --add-section .gdb_index=symfile.gdb-index \
20261 --set-section-flags .gdb_index=readonly symfile symfile
20262@end smallexample
20263
437afbb8
JK
20264Or for @code{-dwarf-5}:
20265
20266@smallexample
20267$ objcopy --dump-section .debug_str=symfile.debug_str.new symfile
20268$ cat symfile.debug_str >>symfile.debug_str.new
20269$ objcopy --add-section .debug_names=symfile.gdb-index \
20270 --set-section-flags .debug_names=readonly \
20271 --update-section .debug_str=symfile.debug_str.new symfile symfile
20272@end smallexample
20273
e615022a
DE
20274@value{GDBN} will normally ignore older versions of @file{.gdb_index}
20275sections that have been deprecated. Usually they are deprecated because
20276they are missing a new feature or have performance issues.
20277To tell @value{GDBN} to use a deprecated index section anyway
20278specify @code{set use-deprecated-index-sections on}.
20279The default is @code{off}.
20280This can speed up startup, but may result in some functionality being lost.
20281@xref{Index Section Format}.
20282
20283@emph{Warning:} Setting @code{use-deprecated-index-sections} to @code{on}
20284must be done before gdb reads the file. The following will not work:
20285
20286@smallexample
20287$ gdb -ex "set use-deprecated-index-sections on" <program>
20288@end smallexample
20289
20290Instead you must do, for example,
20291
20292@smallexample
20293$ gdb -iex "set use-deprecated-index-sections on" <program>
20294@end smallexample
20295
9291a0cd
TT
20296There are currently some limitation on indices. They only work when
20297for DWARF debugging information, not stabs. And, they do not
20298currently work for programs using Ada.
20299
7d11235d
SM
20300@subsection Automatic symbol index cache
20301
20302It is possible for @value{GDBN} to automatically save a copy of this index in a
20303cache on disk and retrieve it from there when loading the same binary in the
20304future. This feature can be turned on with @kbd{set index-cache on}. The
20305following commands can be used to tweak the behavior of the index cache.
20306
20307@table @code
20308
20309@item set index-cache on
20310@itemx set index-cache off
20311Enable or disable the use of the symbol index cache.
20312
20313@item set index-cache directory @var{directory}
20314@itemx show index-cache directory
e6cd1dc1
TT
20315Set/show the directory where index files will be saved.
20316
20317The default value for this directory depends on the host platform. On
20318most systems, the index is cached in the @file{gdb} subdirectory of
20319the directory pointed to by the @env{XDG_CACHE_HOME} environment
20320variable, if it is defined, else in the @file{.cache/gdb} subdirectory
20321of your home directory. However, on some systems, the default may
20322differ according to local convention.
7d11235d
SM
20323
20324There is no limit on the disk space used by index cache. It is perfectly safe
20325to delete the content of that directory to free up disk space.
20326
20327@item show index-cache stats
20328Print the number of cache hits and misses since the launch of @value{GDBN}.
20329
20330@end table
20331
6d2ebf8b 20332@node Symbol Errors
79a6e687 20333@section Errors Reading Symbol Files
c906108c
SS
20334
20335While reading a symbol file, @value{GDBN} occasionally encounters problems,
20336such as symbol types it does not recognize, or known bugs in compiler
20337output. By default, @value{GDBN} does not notify you of such problems, since
20338they are relatively common and primarily of interest to people
20339debugging compilers. If you are interested in seeing information
20340about ill-constructed symbol tables, you can either ask @value{GDBN} to print
20341only one message about each such type of problem, no matter how many
20342times the problem occurs; or you can ask @value{GDBN} to print more messages,
20343to see how many times the problems occur, with the @code{set
79a6e687
BW
20344complaints} command (@pxref{Messages/Warnings, ,Optional Warnings and
20345Messages}).
c906108c
SS
20346
20347The messages currently printed, and their meanings, include:
20348
20349@table @code
20350@item inner block not inside outer block in @var{symbol}
20351
20352The symbol information shows where symbol scopes begin and end
20353(such as at the start of a function or a block of statements). This
20354error indicates that an inner scope block is not fully contained
20355in its outer scope blocks.
20356
20357@value{GDBN} circumvents the problem by treating the inner block as if it had
20358the same scope as the outer block. In the error message, @var{symbol}
20359may be shown as ``@code{(don't know)}'' if the outer block is not a
20360function.
20361
20362@item block at @var{address} out of order
20363
20364The symbol information for symbol scope blocks should occur in
20365order of increasing addresses. This error indicates that it does not
20366do so.
20367
20368@value{GDBN} does not circumvent this problem, and has trouble
20369locating symbols in the source file whose symbols it is reading. (You
20370can often determine what source file is affected by specifying
79a6e687
BW
20371@code{set verbose on}. @xref{Messages/Warnings, ,Optional Warnings and
20372Messages}.)
c906108c
SS
20373
20374@item bad block start address patched
20375
20376The symbol information for a symbol scope block has a start address
20377smaller than the address of the preceding source line. This is known
20378to occur in the SunOS 4.1.1 (and earlier) C compiler.
20379
20380@value{GDBN} circumvents the problem by treating the symbol scope block as
20381starting on the previous source line.
20382
20383@item bad string table offset in symbol @var{n}
20384
20385@cindex foo
20386Symbol number @var{n} contains a pointer into the string table which is
20387larger than the size of the string table.
20388
20389@value{GDBN} circumvents the problem by considering the symbol to have the
20390name @code{foo}, which may cause other problems if many symbols end up
20391with this name.
20392
20393@item unknown symbol type @code{0x@var{nn}}
20394
7a292a7a
SS
20395The symbol information contains new data types that @value{GDBN} does
20396not yet know how to read. @code{0x@var{nn}} is the symbol type of the
d4f3574e 20397uncomprehended information, in hexadecimal.
c906108c 20398
7a292a7a
SS
20399@value{GDBN} circumvents the error by ignoring this symbol information.
20400This usually allows you to debug your program, though certain symbols
c906108c 20401are not accessible. If you encounter such a problem and feel like
7a292a7a
SS
20402debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint
20403on @code{complain}, then go up to the function @code{read_dbx_symtab}
20404and examine @code{*bufp} to see the symbol.
c906108c
SS
20405
20406@item stub type has NULL name
c906108c 20407
7a292a7a 20408@value{GDBN} could not find the full definition for a struct or class.
c906108c 20409
7a292a7a 20410@item const/volatile indicator missing (ok if using g++ v1.x), got@dots{}
b37052ae 20411The symbol information for a C@t{++} member function is missing some
7a292a7a
SS
20412information that recent versions of the compiler should have output for
20413it.
c906108c
SS
20414
20415@item info mismatch between compiler and debugger
20416
20417@value{GDBN} could not parse a type specification output by the compiler.
7a292a7a 20418
c906108c
SS
20419@end table
20420
b14b1491
TT
20421@node Data Files
20422@section GDB Data Files
20423
20424@cindex prefix for data files
20425@value{GDBN} will sometimes read an auxiliary data file. These files
20426are kept in a directory known as the @dfn{data directory}.
20427
20428You can set the data directory's name, and view the name @value{GDBN}
20429is currently using.
20430
20431@table @code
20432@kindex set data-directory
20433@item set data-directory @var{directory}
20434Set the directory which @value{GDBN} searches for auxiliary data files
20435to @var{directory}.
20436
20437@kindex show data-directory
20438@item show data-directory
20439Show the directory @value{GDBN} searches for auxiliary data files.
20440@end table
20441
20442@cindex default data directory
20443@cindex @samp{--with-gdb-datadir}
20444You can set the default data directory by using the configure-time
20445@samp{--with-gdb-datadir} option. If the data directory is inside
20446@value{GDBN}'s configured binary prefix (set with @samp{--prefix} or
20447@samp{--exec-prefix}), then the default data directory will be updated
20448automatically if the installed @value{GDBN} is moved to a new
20449location.
20450
aae1c79a
DE
20451The data directory may also be specified with the
20452@code{--data-directory} command line option.
20453@xref{Mode Options}.
20454
6d2ebf8b 20455@node Targets
c906108c 20456@chapter Specifying a Debugging Target
7a292a7a 20457
c906108c 20458@cindex debugging target
c906108c 20459A @dfn{target} is the execution environment occupied by your program.
53a5351d
JM
20460
20461Often, @value{GDBN} runs in the same host environment as your program;
20462in that case, the debugging target is specified as a side effect when
20463you use the @code{file} or @code{core} commands. When you need more
c906108c
SS
20464flexibility---for example, running @value{GDBN} on a physically separate
20465host, or controlling a standalone system over a serial port or a
53a5351d
JM
20466realtime system over a TCP/IP connection---you can use the @code{target}
20467command to specify one of the target types configured for @value{GDBN}
79a6e687 20468(@pxref{Target Commands, ,Commands for Managing Targets}).
c906108c 20469
a8f24a35
EZ
20470@cindex target architecture
20471It is possible to build @value{GDBN} for several different @dfn{target
20472architectures}. When @value{GDBN} is built like that, you can choose
20473one of the available architectures with the @kbd{set architecture}
20474command.
20475
20476@table @code
20477@kindex set architecture
20478@kindex show architecture
20479@item set architecture @var{arch}
20480This command sets the current target architecture to @var{arch}. The
20481value of @var{arch} can be @code{"auto"}, in addition to one of the
20482supported architectures.
20483
20484@item show architecture
20485Show the current target architecture.
9c16f35a
EZ
20486
20487@item set processor
20488@itemx processor
20489@kindex set processor
20490@kindex show processor
20491These are alias commands for, respectively, @code{set architecture}
20492and @code{show architecture}.
a8f24a35
EZ
20493@end table
20494
c906108c
SS
20495@menu
20496* Active Targets:: Active targets
20497* Target Commands:: Commands for managing targets
c906108c 20498* Byte Order:: Choosing target byte order
c906108c
SS
20499@end menu
20500
6d2ebf8b 20501@node Active Targets
79a6e687 20502@section Active Targets
7a292a7a 20503
c906108c
SS
20504@cindex stacking targets
20505@cindex active targets
20506@cindex multiple targets
20507
8ea5bce5 20508There are multiple classes of targets such as: processes, executable files or
c0edd9ed
JK
20509recording sessions. Core files belong to the process class, making core file
20510and process mutually exclusive. Otherwise, @value{GDBN} can work concurrently
20511on multiple active targets, one in each class. This allows you to (for
20512example) start a process and inspect its activity, while still having access to
20513the executable file after the process finishes. Or if you start process
20514recording (@pxref{Reverse Execution}) and @code{reverse-step} there, you are
20515presented a virtual layer of the recording target, while the process target
20516remains stopped at the chronologically last point of the process execution.
20517
20518Use the @code{core-file} and @code{exec-file} commands to select a new core
20519file or executable target (@pxref{Files, ,Commands to Specify Files}). To
20520specify as a target a process that is already running, use the @code{attach}
20521command (@pxref{Attach, ,Debugging an Already-running Process}).
c906108c 20522
6d2ebf8b 20523@node Target Commands
79a6e687 20524@section Commands for Managing Targets
c906108c
SS
20525
20526@table @code
20527@item target @var{type} @var{parameters}
7a292a7a
SS
20528Connects the @value{GDBN} host environment to a target machine or
20529process. A target is typically a protocol for talking to debugging
20530facilities. You use the argument @var{type} to specify the type or
20531protocol of the target machine.
c906108c
SS
20532
20533Further @var{parameters} are interpreted by the target protocol, but
20534typically include things like device names or host names to connect
20535with, process numbers, and baud rates.
c906108c
SS
20536
20537The @code{target} command does not repeat if you press @key{RET} again
20538after executing the command.
20539
20540@kindex help target
20541@item help target
20542Displays the names of all targets available. To display targets
20543currently selected, use either @code{info target} or @code{info files}
79a6e687 20544(@pxref{Files, ,Commands to Specify Files}).
c906108c
SS
20545
20546@item help target @var{name}
20547Describe a particular target, including any parameters necessary to
20548select it.
20549
20550@kindex set gnutarget
20551@item set gnutarget @var{args}
5d161b24 20552@value{GDBN} uses its own library BFD to read your files. @value{GDBN}
c906108c 20553knows whether it is reading an @dfn{executable},
5d161b24
DB
20554a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format
20555with the @code{set gnutarget} command. Unlike most @code{target} commands,
c906108c
SS
20556with @code{gnutarget} the @code{target} refers to a program, not a machine.
20557
d4f3574e 20558@quotation
c906108c
SS
20559@emph{Warning:} To specify a file format with @code{set gnutarget},
20560you must know the actual BFD name.
d4f3574e 20561@end quotation
c906108c 20562
d4f3574e 20563@noindent
79a6e687 20564@xref{Files, , Commands to Specify Files}.
c906108c 20565
5d161b24 20566@kindex show gnutarget
c906108c
SS
20567@item show gnutarget
20568Use the @code{show gnutarget} command to display what file format
20569@code{gnutarget} is set to read. If you have not set @code{gnutarget},
20570@value{GDBN} will determine the file format for each file automatically,
c4957902 20571and @code{show gnutarget} displays @samp{The current BFD target is "auto"}.
c906108c
SS
20572@end table
20573
4644b6e3 20574@cindex common targets
c906108c
SS
20575Here are some common targets (available, or not, depending on the GDB
20576configuration):
c906108c
SS
20577
20578@table @code
4644b6e3 20579@kindex target
c906108c 20580@item target exec @var{program}
4644b6e3 20581@cindex executable file target
c906108c
SS
20582An executable file. @samp{target exec @var{program}} is the same as
20583@samp{exec-file @var{program}}.
20584
c906108c 20585@item target core @var{filename}
4644b6e3 20586@cindex core dump file target
c906108c
SS
20587A core dump file. @samp{target core @var{filename}} is the same as
20588@samp{core-file @var{filename}}.
c906108c 20589
1a10341b 20590@item target remote @var{medium}
4644b6e3 20591@cindex remote target
1a10341b
JB
20592A remote system connected to @value{GDBN} via a serial line or network
20593connection. This command tells @value{GDBN} to use its own remote
20594protocol over @var{medium} for debugging. @xref{Remote Debugging}.
20595
20596For example, if you have a board connected to @file{/dev/ttya} on the
20597machine running @value{GDBN}, you could say:
20598
20599@smallexample
20600target remote /dev/ttya
20601@end smallexample
20602
20603@code{target remote} supports the @code{load} command. This is only
20604useful if you have some other way of getting the stub to the target
20605system, and you can put it somewhere in memory where it won't get
20606clobbered by the download.
c906108c 20607
ee8e71d4 20608@item target sim @r{[}@var{simargs}@r{]} @dots{}
4644b6e3 20609@cindex built-in simulator target
2df3850c 20610Builtin CPU simulator. @value{GDBN} includes simulators for most architectures.
104c1213 20611In general,
474c8240 20612@smallexample
104c1213
JM
20613 target sim
20614 load
20615 run
474c8240 20616@end smallexample
d4f3574e 20617@noindent
104c1213 20618works; however, you cannot assume that a specific memory map, device
d4f3574e 20619drivers, or even basic I/O is available, although some simulators do
104c1213
JM
20620provide these. For info about any processor-specific simulator details,
20621see the appropriate section in @ref{Embedded Processors, ,Embedded
20622Processors}.
20623
6a3cb8e8
PA
20624@item target native
20625@cindex native target
20626Setup for local/native process debugging. Useful to make the
20627@code{run} command spawn native processes (likewise @code{attach},
20628etc.@:) even when @code{set auto-connect-native-target} is @code{off}
20629(@pxref{set auto-connect-native-target}).
20630
c906108c
SS
20631@end table
20632
5d161b24 20633Different targets are available on different configurations of @value{GDBN};
c906108c 20634your configuration may have more or fewer targets.
c906108c 20635
721c2651
EZ
20636Many remote targets require you to download the executable's code once
20637you've successfully established a connection. You may wish to control
3d00d119
DJ
20638various aspects of this process.
20639
20640@table @code
721c2651
EZ
20641
20642@item set hash
20643@kindex set hash@r{, for remote monitors}
20644@cindex hash mark while downloading
20645This command controls whether a hash mark @samp{#} is displayed while
20646downloading a file to the remote monitor. If on, a hash mark is
20647displayed after each S-record is successfully downloaded to the
20648monitor.
20649
20650@item show hash
20651@kindex show hash@r{, for remote monitors}
20652Show the current status of displaying the hash mark.
20653
20654@item set debug monitor
20655@kindex set debug monitor
20656@cindex display remote monitor communications
20657Enable or disable display of communications messages between
20658@value{GDBN} and the remote monitor.
20659
20660@item show debug monitor
20661@kindex show debug monitor
20662Show the current status of displaying communications between
20663@value{GDBN} and the remote monitor.
a8f24a35 20664@end table
c906108c
SS
20665
20666@table @code
20667
5cf30ebf
LM
20668@kindex load @var{filename} @var{offset}
20669@item load @var{filename} @var{offset}
8edfe269 20670@anchor{load}
c906108c
SS
20671Depending on what remote debugging facilities are configured into
20672@value{GDBN}, the @code{load} command may be available. Where it exists, it
20673is meant to make @var{filename} (an executable) available for debugging
20674on the remote system---by downloading, or dynamic linking, for example.
20675@code{load} also records the @var{filename} symbol table in @value{GDBN}, like
20676the @code{add-symbol-file} command.
20677
20678If your @value{GDBN} does not have a @code{load} command, attempting to
20679execute it gets the error message ``@code{You can't do that when your
20680target is @dots{}}''
c906108c
SS
20681
20682The file is loaded at whatever address is specified in the executable.
20683For some object file formats, you can specify the load address when you
20684link the program; for other formats, like a.out, the object file format
20685specifies a fixed address.
20686@c FIXME! This would be a good place for an xref to the GNU linker doc.
20687
5cf30ebf
LM
20688It is also possible to tell @value{GDBN} to load the executable file at a
20689specific offset described by the optional argument @var{offset}. When
20690@var{offset} is provided, @var{filename} must also be provided.
20691
68437a39
DJ
20692Depending on the remote side capabilities, @value{GDBN} may be able to
20693load programs into flash memory.
20694
c906108c
SS
20695@code{load} does not repeat if you press @key{RET} again after using it.
20696@end table
20697
78cbbba8
LM
20698@table @code
20699
20700@kindex flash-erase
20701@item flash-erase
20702@anchor{flash-erase}
20703
20704Erases all known flash memory regions on the target.
20705
20706@end table
20707
6d2ebf8b 20708@node Byte Order
79a6e687 20709@section Choosing Target Byte Order
7a292a7a 20710
c906108c
SS
20711@cindex choosing target byte order
20712@cindex target byte order
c906108c 20713
eb17f351 20714Some types of processors, such as the @acronym{MIPS}, PowerPC, and Renesas SH,
c906108c
SS
20715offer the ability to run either big-endian or little-endian byte
20716orders. Usually the executable or symbol will include a bit to
20717designate the endian-ness, and you will not need to worry about
20718which to use. However, you may still find it useful to adjust
d4f3574e 20719@value{GDBN}'s idea of processor endian-ness manually.
c906108c
SS
20720
20721@table @code
4644b6e3 20722@kindex set endian
c906108c
SS
20723@item set endian big
20724Instruct @value{GDBN} to assume the target is big-endian.
20725
c906108c
SS
20726@item set endian little
20727Instruct @value{GDBN} to assume the target is little-endian.
20728
c906108c
SS
20729@item set endian auto
20730Instruct @value{GDBN} to use the byte order associated with the
20731executable.
20732
20733@item show endian
20734Display @value{GDBN}'s current idea of the target byte order.
20735
20736@end table
20737
4b2dfa9d
MR
20738If the @code{set endian auto} mode is in effect and no executable has
20739been selected, then the endianness used is the last one chosen either
20740by one of the @code{set endian big} and @code{set endian little}
20741commands or by inferring from the last executable used. If no
20742endianness has been previously chosen, then the default for this mode
20743is inferred from the target @value{GDBN} has been built for, and is
20744@code{little} if the name of the target CPU has an @code{el} suffix
20745and @code{big} otherwise.
20746
c906108c
SS
20747Note that these commands merely adjust interpretation of symbolic
20748data on the host, and that they have absolutely no effect on the
20749target system.
20750
ea35711c
DJ
20751
20752@node Remote Debugging
20753@chapter Debugging Remote Programs
c906108c
SS
20754@cindex remote debugging
20755
20756If you are trying to debug a program running on a machine that cannot run
5d161b24
DB
20757@value{GDBN} in the usual way, it is often useful to use remote debugging.
20758For example, you might use remote debugging on an operating system kernel,
c906108c
SS
20759or on a small system which does not have a general purpose operating system
20760powerful enough to run a full-featured debugger.
20761
20762Some configurations of @value{GDBN} have special serial or TCP/IP interfaces
20763to make this work with particular debugging targets. In addition,
5d161b24 20764@value{GDBN} comes with a generic serial protocol (specific to @value{GDBN},
c906108c
SS
20765but not specific to any particular target system) which you can use if you
20766write the remote stubs---the code that runs on the remote system to
20767communicate with @value{GDBN}.
20768
20769Other remote targets may be available in your
20770configuration of @value{GDBN}; use @code{help target} to list them.
c906108c 20771
6b2f586d 20772@menu
07f31aa6 20773* Connecting:: Connecting to a remote target
a6b151f1 20774* File Transfer:: Sending files to a remote system
6b2f586d 20775* Server:: Using the gdbserver program
79a6e687
BW
20776* Remote Configuration:: Remote configuration
20777* Remote Stub:: Implementing a remote stub
6b2f586d
AC
20778@end menu
20779
07f31aa6 20780@node Connecting
79a6e687 20781@section Connecting to a Remote Target
19d9d4ef
DB
20782@cindex remote debugging, connecting
20783@cindex @code{gdbserver}, connecting
20784@cindex remote debugging, types of connections
20785@cindex @code{gdbserver}, types of connections
20786@cindex @code{gdbserver}, @code{target remote} mode
20787@cindex @code{gdbserver}, @code{target extended-remote} mode
20788
20789This section describes how to connect to a remote target, including the
20790types of connections and their differences, how to set up executable and
20791symbol files on the host and target, and the commands used for
20792connecting to and disconnecting from the remote target.
20793
20794@subsection Types of Remote Connections
20795
20796@value{GDBN} supports two types of remote connections, @code{target remote}
20797mode and @code{target extended-remote} mode. Note that many remote targets
20798support only @code{target remote} mode. There are several major
20799differences between the two types of connections, enumerated here:
20800
20801@table @asis
20802
20803@cindex remote debugging, detach and program exit
20804@item Result of detach or program exit
20805@strong{With target remote mode:} When the debugged program exits or you
20806detach from it, @value{GDBN} disconnects from the target. When using
20807@code{gdbserver}, @code{gdbserver} will exit.
20808
20809@strong{With target extended-remote mode:} When the debugged program exits or
20810you detach from it, @value{GDBN} remains connected to the target, even
20811though no program is running. You can rerun the program, attach to a
20812running program, or use @code{monitor} commands specific to the target.
20813
20814When using @code{gdbserver} in this case, it does not exit unless it was
20815invoked using the @option{--once} option. If the @option{--once} option
20816was not used, you can ask @code{gdbserver} to exit using the
20817@code{monitor exit} command (@pxref{Monitor Commands for gdbserver}).
20818
20819@item Specifying the program to debug
20820For both connection types you use the @code{file} command to specify the
20821program on the host system. If you are using @code{gdbserver} there are
20822some differences in how to specify the location of the program on the
20823target.
20824
20825@strong{With target remote mode:} You must either specify the program to debug
20826on the @code{gdbserver} command line or use the @option{--attach} option
20827(@pxref{Attaching to a program,,Attaching to a Running Program}).
20828
20829@cindex @option{--multi}, @code{gdbserver} option
20830@strong{With target extended-remote mode:} You may specify the program to debug
20831on the @code{gdbserver} command line, or you can load the program or attach
20832to it using @value{GDBN} commands after connecting to @code{gdbserver}.
20833
20834@anchor{--multi Option in Types of Remote Connnections}
20835You can start @code{gdbserver} without supplying an initial command to run
20836or process ID to attach. To do this, use the @option{--multi} command line
20837option. Then you can connect using @code{target extended-remote} and start
20838the program you want to debug (see below for details on using the
20839@code{run} command in this scenario). Note that the conditions under which
20840@code{gdbserver} terminates depend on how @value{GDBN} connects to it
20841(@code{target remote} or @code{target extended-remote}). The
20842@option{--multi} option to @code{gdbserver} has no influence on that.
07f31aa6 20843
19d9d4ef
DB
20844@item The @code{run} command
20845@strong{With target remote mode:} The @code{run} command is not
20846supported. Once a connection has been established, you can use all
20847the usual @value{GDBN} commands to examine and change data. The
20848remote program is already running, so you can use commands like
20849@kbd{step} and @kbd{continue}.
20850
20851@strong{With target extended-remote mode:} The @code{run} command is
20852supported. The @code{run} command uses the value set by
20853@code{set remote exec-file} (@pxref{set remote exec-file}) to select
20854the program to run. Command line arguments are supported, except for
20855wildcard expansion and I/O redirection (@pxref{Arguments}).
20856
20857If you specify the program to debug on the command line, then the
20858@code{run} command is not required to start execution, and you can
20859resume using commands like @kbd{step} and @kbd{continue} as with
20860@code{target remote} mode.
20861
20862@anchor{Attaching in Types of Remote Connections}
20863@item Attaching
20864@strong{With target remote mode:} The @value{GDBN} command @code{attach} is
20865not supported. To attach to a running program using @code{gdbserver}, you
20866must use the @option{--attach} option (@pxref{Running gdbserver}).
20867
20868@strong{With target extended-remote mode:} To attach to a running program,
20869you may use the @code{attach} command after the connection has been
20870established. If you are using @code{gdbserver}, you may also invoke
20871@code{gdbserver} using the @option{--attach} option
20872(@pxref{Running gdbserver}).
20873
20874@end table
20875
20876@anchor{Host and target files}
20877@subsection Host and Target Files
20878@cindex remote debugging, symbol files
20879@cindex symbol files, remote debugging
20880
20881@value{GDBN}, running on the host, needs access to symbol and debugging
20882information for your program running on the target. This requires
20883access to an unstripped copy of your program, and possibly any associated
20884symbol files. Note that this section applies equally to both @code{target
20885remote} mode and @code{target extended-remote} mode.
20886
20887Some remote targets (@pxref{qXfer executable filename read}, and
20888@pxref{Host I/O Packets}) allow @value{GDBN} to access program files over
20889the same connection used to communicate with @value{GDBN}. With such a
20890target, if the remote program is unstripped, the only command you need is
20891@code{target remote} (or @code{target extended-remote}).
20892
20893If the remote program is stripped, or the target does not support remote
20894program file access, start up @value{GDBN} using the name of the local
1b6e6f5c 20895unstripped copy of your program as the first argument, or use the
19d9d4ef
DB
20896@code{file} command. Use @code{set sysroot} to specify the location (on
20897the host) of target libraries (unless your @value{GDBN} was compiled with
20898the correct sysroot using @code{--with-sysroot}). Alternatively, you
20899may use @code{set solib-search-path} to specify how @value{GDBN} locates
20900target libraries.
20901
20902The symbol file and target libraries must exactly match the executable
20903and libraries on the target, with one exception: the files on the host
20904system should not be stripped, even if the files on the target system
20905are. Mismatched or missing files will lead to confusing results
20906during debugging. On @sc{gnu}/Linux targets, mismatched or missing
20907files may also prevent @code{gdbserver} from debugging multi-threaded
20908programs.
07f31aa6 20909
19d9d4ef
DB
20910@subsection Remote Connection Commands
20911@cindex remote connection commands
c1168a2f
JD
20912@value{GDBN} can communicate with the target over a serial line, a
20913local Unix domain socket, or
86941c27
JB
20914over an @acronym{IP} network using @acronym{TCP} or @acronym{UDP}. In
20915each case, @value{GDBN} uses the same protocol for debugging your
20916program; only the medium carrying the debugging packets varies. The
19d9d4ef
DB
20917@code{target remote} and @code{target extended-remote} commands
20918establish a connection to the target. Both commands accept the same
20919arguments, which indicate the medium to use:
86941c27
JB
20920
20921@table @code
20922
20923@item target remote @var{serial-device}
19d9d4ef 20924@itemx target extended-remote @var{serial-device}
07f31aa6 20925@cindex serial line, @code{target remote}
86941c27
JB
20926Use @var{serial-device} to communicate with the target. For example,
20927to use a serial line connected to the device named @file{/dev/ttyb}:
20928
20929@smallexample
20930target remote /dev/ttyb
20931@end smallexample
20932
07f31aa6 20933If you're using a serial line, you may want to give @value{GDBN} the
2446f5ea 20934@samp{--baud} option, or use the @code{set serial baud} command
0d12017b 20935(@pxref{Remote Configuration, set serial baud}) before the
9c16f35a 20936@code{target} command.
07f31aa6 20937
c1168a2f
JD
20938@item target remote @var{local-socket}
20939@itemx target extended-remote @var{local-socket}
20940@cindex local socket, @code{target remote}
20941@cindex Unix domain socket
20942Use @var{local-socket} to communicate with the target. For example,
20943to use a local Unix domain socket bound to the file system entry @file{/tmp/gdb-socket0}:
20944
20945@smallexample
20946target remote /tmp/gdb-socket0
20947@end smallexample
20948
20949Note that this command has the same form as the command to connect
20950to a serial line. @value{GDBN} will automatically determine which
20951kind of file you have specified and will make the appropriate kind
20952of connection.
20953This feature is not available if the host system does not support
20954Unix domain sockets.
20955
86941c27 20956@item target remote @code{@var{host}:@var{port}}
c7ab0aef 20957@itemx target remote @code{@var{[host]}:@var{port}}
86941c27 20958@itemx target remote @code{tcp:@var{host}:@var{port}}
c7ab0aef
SDJ
20959@itemx target remote @code{tcp:@var{[host]}:@var{port}}
20960@itemx target remote @code{tcp4:@var{host}:@var{port}}
20961@itemx target remote @code{tcp6:@var{host}:@var{port}}
20962@itemx target remote @code{tcp6:@var{[host]}:@var{port}}
19d9d4ef 20963@itemx target extended-remote @code{@var{host}:@var{port}}
c7ab0aef 20964@itemx target extended-remote @code{@var{[host]}:@var{port}}
19d9d4ef 20965@itemx target extended-remote @code{tcp:@var{host}:@var{port}}
c7ab0aef
SDJ
20966@itemx target extended-remote @code{tcp:@var{[host]}:@var{port}}
20967@itemx target extended-remote @code{tcp4:@var{host}:@var{port}}
20968@itemx target extended-remote @code{tcp6:@var{host}:@var{port}}
20969@itemx target extended-remote @code{tcp6:@var{[host]}:@var{port}}
86941c27 20970@cindex @acronym{TCP} port, @code{target remote}
6a0b3457 20971Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
c7ab0aef
SDJ
20972The @var{host} may be either a host name, a numeric @acronym{IPv4}
20973address, or a numeric @acronym{IPv6} address (with or without the
20974square brackets to separate the address from the port); @var{port}
20975must be a decimal number. The @var{host} could be the target machine
20976itself, if it is directly connected to the net, or it might be a
20977terminal server which in turn has a serial line to the target.
07f31aa6 20978
86941c27
JB
20979For example, to connect to port 2828 on a terminal server named
20980@code{manyfarms}:
07f31aa6
DJ
20981
20982@smallexample
20983target remote manyfarms:2828
20984@end smallexample
20985
c7ab0aef
SDJ
20986To connect to port 2828 on a terminal server whose address is
20987@code{2001:0db8:85a3:0000:0000:8a2e:0370:7334}, you can either use the
20988square bracket syntax:
20989
20990@smallexample
20991target remote [2001:0db8:85a3:0000:0000:8a2e:0370:7334]:2828
20992@end smallexample
20993
20994@noindent
20995or explicitly specify the @acronym{IPv6} protocol:
20996
20997@smallexample
20998target remote tcp6:2001:0db8:85a3:0000:0000:8a2e:0370:7334:2828
20999@end smallexample
21000
21001This last example may be confusing to the reader, because there is no
21002visible separation between the hostname and the port number.
21003Therefore, we recommend the user to provide @acronym{IPv6} addresses
21004using square brackets for clarity. However, it is important to
21005mention that for @value{GDBN} there is no ambiguity: the number after
21006the last colon is considered to be the port number.
21007
86941c27
JB
21008If your remote target is actually running on the same machine as your
21009debugger session (e.g.@: a simulator for your target running on the
21010same host), you can omit the hostname. For example, to connect to
21011port 1234 on your local machine:
07f31aa6
DJ
21012
21013@smallexample
21014target remote :1234
21015@end smallexample
21016@noindent
21017
21018Note that the colon is still required here.
21019
86941c27 21020@item target remote @code{udp:@var{host}:@var{port}}
c7ab0aef
SDJ
21021@itemx target remote @code{udp:@var{[host]}:@var{port}}
21022@itemx target remote @code{udp4:@var{host}:@var{port}}
21023@itemx target remote @code{udp6:@var{[host]}:@var{port}}
21024@itemx target extended-remote @code{udp:@var{host}:@var{port}}
19d9d4ef 21025@itemx target extended-remote @code{udp:@var{host}:@var{port}}
c7ab0aef
SDJ
21026@itemx target extended-remote @code{udp:@var{[host]}:@var{port}}
21027@itemx target extended-remote @code{udp4:@var{host}:@var{port}}
21028@itemx target extended-remote @code{udp6:@var{host}:@var{port}}
21029@itemx target extended-remote @code{udp6:@var{[host]}:@var{port}}
86941c27
JB
21030@cindex @acronym{UDP} port, @code{target remote}
21031Debug using @acronym{UDP} packets to @var{port} on @var{host}. For example, to
21032connect to @acronym{UDP} port 2828 on a terminal server named @code{manyfarms}:
07f31aa6
DJ
21033
21034@smallexample
21035target remote udp:manyfarms:2828
21036@end smallexample
21037
86941c27
JB
21038When using a @acronym{UDP} connection for remote debugging, you should
21039keep in mind that the `U' stands for ``Unreliable''. @acronym{UDP}
21040can silently drop packets on busy or unreliable networks, which will
21041cause havoc with your debugging session.
21042
66b8c7f6 21043@item target remote | @var{command}
19d9d4ef 21044@itemx target extended-remote | @var{command}
66b8c7f6
JB
21045@cindex pipe, @code{target remote} to
21046Run @var{command} in the background and communicate with it using a
21047pipe. The @var{command} is a shell command, to be parsed and expanded
21048by the system's command shell, @code{/bin/sh}; it should expect remote
21049protocol packets on its standard input, and send replies on its
21050standard output. You could use this to run a stand-alone simulator
21051that speaks the remote debugging protocol, to make net connections
21052using programs like @code{ssh}, or for other similar tricks.
21053
21054If @var{command} closes its standard output (perhaps by exiting),
21055@value{GDBN} will try to send it a @code{SIGTERM} signal. (If the
21056program has already exited, this will have no effect.)
21057
86941c27 21058@end table
07f31aa6 21059
07f31aa6
DJ
21060@cindex interrupting remote programs
21061@cindex remote programs, interrupting
21062Whenever @value{GDBN} is waiting for the remote program, if you type the
c8aa23ab 21063interrupt character (often @kbd{Ctrl-c}), @value{GDBN} attempts to stop the
07f31aa6
DJ
21064program. This may or may not succeed, depending in part on the hardware
21065and the serial drivers the remote system uses. If you type the
21066interrupt character once again, @value{GDBN} displays this prompt:
21067
21068@smallexample
21069Interrupted while waiting for the program.
21070Give up (and stop debugging it)? (y or n)
21071@end smallexample
21072
19d9d4ef
DB
21073In @code{target remote} mode, if you type @kbd{y}, @value{GDBN} abandons
21074the remote debugging session. (If you decide you want to try again later,
21075you can use @kbd{target remote} again to connect once more.) If you type
21076@kbd{n}, @value{GDBN} goes back to waiting.
21077
21078In @code{target extended-remote} mode, typing @kbd{n} will leave
21079@value{GDBN} connected to the target.
07f31aa6
DJ
21080
21081@table @code
21082@kindex detach (remote)
21083@item detach
21084When you have finished debugging the remote program, you can use the
21085@code{detach} command to release it from @value{GDBN} control.
21086Detaching from the target normally resumes its execution, but the results
21087will depend on your particular remote stub. After the @code{detach}
19d9d4ef
DB
21088command in @code{target remote} mode, @value{GDBN} is free to connect to
21089another target. In @code{target extended-remote} mode, @value{GDBN} is
21090still connected to the target.
07f31aa6
DJ
21091
21092@kindex disconnect
21093@item disconnect
19d9d4ef 21094The @code{disconnect} command closes the connection to the target, and
07f31aa6
DJ
21095the target is generally not resumed. It will wait for @value{GDBN}
21096(this instance or another one) to connect and continue debugging. After
21097the @code{disconnect} command, @value{GDBN} is again free to connect to
21098another target.
09d4efe1
EZ
21099
21100@cindex send command to remote monitor
fad38dfa
EZ
21101@cindex extend @value{GDBN} for remote targets
21102@cindex add new commands for external monitor
09d4efe1
EZ
21103@kindex monitor
21104@item monitor @var{cmd}
fad38dfa
EZ
21105This command allows you to send arbitrary commands directly to the
21106remote monitor. Since @value{GDBN} doesn't care about the commands it
21107sends like this, this command is the way to extend @value{GDBN}---you
21108can add new commands that only the external monitor will understand
21109and implement.
07f31aa6
DJ
21110@end table
21111
a6b151f1
DJ
21112@node File Transfer
21113@section Sending files to a remote system
21114@cindex remote target, file transfer
21115@cindex file transfer
21116@cindex sending files to remote systems
21117
21118Some remote targets offer the ability to transfer files over the same
21119connection used to communicate with @value{GDBN}. This is convenient
21120for targets accessible through other means, e.g.@: @sc{gnu}/Linux systems
21121running @code{gdbserver} over a network interface. For other targets,
21122e.g.@: embedded devices with only a single serial port, this may be
21123the only way to upload or download files.
21124
21125Not all remote targets support these commands.
21126
21127@table @code
21128@kindex remote put
21129@item remote put @var{hostfile} @var{targetfile}
21130Copy file @var{hostfile} from the host system (the machine running
21131@value{GDBN}) to @var{targetfile} on the target system.
21132
21133@kindex remote get
21134@item remote get @var{targetfile} @var{hostfile}
21135Copy file @var{targetfile} from the target system to @var{hostfile}
21136on the host system.
21137
21138@kindex remote delete
21139@item remote delete @var{targetfile}
21140Delete @var{targetfile} from the target system.
21141
21142@end table
21143
6f05cf9f 21144@node Server
79a6e687 21145@section Using the @code{gdbserver} Program
6f05cf9f
AC
21146
21147@kindex gdbserver
21148@cindex remote connection without stubs
21149@code{gdbserver} is a control program for Unix-like systems, which
21150allows you to connect your program with a remote @value{GDBN} via
19d9d4ef
DB
21151@code{target remote} or @code{target extended-remote}---but without
21152linking in the usual debugging stub.
6f05cf9f
AC
21153
21154@code{gdbserver} is not a complete replacement for the debugging stubs,
21155because it requires essentially the same operating-system facilities
21156that @value{GDBN} itself does. In fact, a system that can run
21157@code{gdbserver} to connect to a remote @value{GDBN} could also run
21158@value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless,
21159because it is a much smaller program than @value{GDBN} itself. It is
21160also easier to port than all of @value{GDBN}, so you may be able to get
21161started more quickly on a new system by using @code{gdbserver}.
21162Finally, if you develop code for real-time systems, you may find that
21163the tradeoffs involved in real-time operation make it more convenient to
21164do as much development work as possible on another system, for example
21165by cross-compiling. You can use @code{gdbserver} to make a similar
21166choice for debugging.
21167
21168@value{GDBN} and @code{gdbserver} communicate via either a serial line
21169or a TCP connection, using the standard @value{GDBN} remote serial
21170protocol.
21171
2d717e4f
DJ
21172@quotation
21173@emph{Warning:} @code{gdbserver} does not have any built-in security.
21174Do not run @code{gdbserver} connected to any public network; a
21175@value{GDBN} connection to @code{gdbserver} provides access to the
21176target system with the same privileges as the user running
21177@code{gdbserver}.
21178@end quotation
21179
19d9d4ef 21180@anchor{Running gdbserver}
2d717e4f
DJ
21181@subsection Running @code{gdbserver}
21182@cindex arguments, to @code{gdbserver}
d9b1a651 21183@cindex @code{gdbserver}, command-line arguments
2d717e4f
DJ
21184
21185Run @code{gdbserver} on the target system. You need a copy of the
21186program you want to debug, including any libraries it requires.
6f05cf9f
AC
21187@code{gdbserver} does not need your program's symbol table, so you can
21188strip the program if necessary to save space. @value{GDBN} on the host
21189system does all the symbol handling.
21190
21191To use the server, you must tell it how to communicate with @value{GDBN};
56460a61 21192the name of your program; and the arguments for your program. The usual
6f05cf9f
AC
21193syntax is:
21194
21195@smallexample
21196target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
21197@end smallexample
21198
6cf36756
SM
21199@var{comm} is either a device name (to use a serial line), or a TCP
21200hostname and portnumber, or @code{-} or @code{stdio} to use
21201stdin/stdout of @code{gdbserver}.
e0f9f062 21202For example, to debug Emacs with the argument
6f05cf9f
AC
21203@samp{foo.txt} and communicate with @value{GDBN} over the serial port
21204@file{/dev/com1}:
21205
21206@smallexample
21207target> gdbserver /dev/com1 emacs foo.txt
21208@end smallexample
21209
6cf36756
SM
21210@code{gdbserver} waits passively for the host @value{GDBN} to communicate
21211with it.
6f05cf9f
AC
21212
21213To use a TCP connection instead of a serial line:
21214
21215@smallexample
21216target> gdbserver host:2345 emacs foo.txt
21217@end smallexample
21218
21219The only difference from the previous example is the first argument,
21220specifying that you are communicating with the host @value{GDBN} via
21221TCP. The @samp{host:2345} argument means that @code{gdbserver} is to
21222expect a TCP connection from machine @samp{host} to local TCP port 2345.
21223(Currently, the @samp{host} part is ignored.) You can choose any number
21224you want for the port number as long as it does not conflict with any
21225TCP ports already in use on the target system (for example, @code{23} is
21226reserved for @code{telnet}).@footnote{If you choose a port number that
21227conflicts with another service, @code{gdbserver} prints an error message
21228and exits.} You must use the same port number with the host @value{GDBN}
21229@code{target remote} command.
21230
6cf36756
SM
21231The @code{stdio} connection is useful when starting @code{gdbserver}
21232with ssh:
e0f9f062
DE
21233
21234@smallexample
6cf36756 21235(gdb) target remote | ssh -T hostname gdbserver - hello
e0f9f062
DE
21236@end smallexample
21237
6cf36756
SM
21238The @samp{-T} option to ssh is provided because we don't need a remote pty,
21239and we don't want escape-character handling. Ssh does this by default when
21240a command is provided, the flag is provided to make it explicit.
21241You could elide it if you want to.
e0f9f062 21242
6cf36756
SM
21243Programs started with stdio-connected gdbserver have @file{/dev/null} for
21244@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
21245display through a pipe connected to gdbserver.
21246Both @code{stdout} and @code{stderr} use the same pipe.
e0f9f062 21247
19d9d4ef 21248@anchor{Attaching to a program}
2d717e4f 21249@subsubsection Attaching to a Running Program
d9b1a651
EZ
21250@cindex attach to a program, @code{gdbserver}
21251@cindex @option{--attach}, @code{gdbserver} option
2d717e4f 21252
56460a61
DJ
21253On some targets, @code{gdbserver} can also attach to running programs.
21254This is accomplished via the @code{--attach} argument. The syntax is:
21255
21256@smallexample
2d717e4f 21257target> gdbserver --attach @var{comm} @var{pid}
56460a61
DJ
21258@end smallexample
21259
19d9d4ef
DB
21260@var{pid} is the process ID of a currently running process. It isn't
21261necessary to point @code{gdbserver} at a binary for the running process.
21262
21263In @code{target extended-remote} mode, you can also attach using the
21264@value{GDBN} attach command
21265(@pxref{Attaching in Types of Remote Connections}).
56460a61 21266
b1fe9455 21267@pindex pidof
b1fe9455
DJ
21268You can debug processes by name instead of process ID if your target has the
21269@code{pidof} utility:
21270
21271@smallexample
2d717e4f 21272target> gdbserver --attach @var{comm} `pidof @var{program}`
b1fe9455
DJ
21273@end smallexample
21274
f822c95b 21275In case more than one copy of @var{program} is running, or @var{program}
b1fe9455
DJ
21276has multiple threads, most versions of @code{pidof} support the
21277@code{-s} option to only return the first process ID.
21278
03f2bd59
JK
21279@subsubsection TCP port allocation lifecycle of @code{gdbserver}
21280
19d9d4ef
DB
21281This section applies only when @code{gdbserver} is run to listen on a TCP
21282port.
03f2bd59
JK
21283
21284@code{gdbserver} normally terminates after all of its debugged processes have
21285terminated in @kbd{target remote} mode. On the other hand, for @kbd{target
21286extended-remote}, @code{gdbserver} stays running even with no processes left.
21287@value{GDBN} normally terminates the spawned debugged process on its exit,
21288which normally also terminates @code{gdbserver} in the @kbd{target remote}
21289mode. Therefore, when the connection drops unexpectedly, and @value{GDBN}
21290cannot ask @code{gdbserver} to kill its debugged processes, @code{gdbserver}
21291stays running even in the @kbd{target remote} mode.
21292
21293When @code{gdbserver} stays running, @value{GDBN} can connect to it again later.
21294Such reconnecting is useful for features like @ref{disconnected tracing}. For
21295completeness, at most one @value{GDBN} can be connected at a time.
21296
21297@cindex @option{--once}, @code{gdbserver} option
21298By default, @code{gdbserver} keeps the listening TCP port open, so that
6e8c5661 21299subsequent connections are possible. However, if you start @code{gdbserver}
03f2bd59
JK
21300with the @option{--once} option, it will stop listening for any further
21301connection attempts after connecting to the first @value{GDBN} session. This
21302means no further connections to @code{gdbserver} will be possible after the
21303first one. It also means @code{gdbserver} will terminate after the first
21304connection with remote @value{GDBN} has closed, even for unexpectedly closed
21305connections and even in the @kbd{target extended-remote} mode. The
21306@option{--once} option allows reusing the same port number for connecting to
21307multiple instances of @code{gdbserver} running on the same host, since each
21308instance closes its port after the first connection.
2d717e4f 21309
87ce2a04 21310@anchor{Other Command-Line Arguments for gdbserver}
2d717e4f
DJ
21311@subsubsection Other Command-Line Arguments for @code{gdbserver}
21312
19d9d4ef
DB
21313You can use the @option{--multi} option to start @code{gdbserver} without
21314specifying a program to debug or a process to attach to. Then you can
21315attach in @code{target extended-remote} mode and run or attach to a
21316program. For more information,
21317@pxref{--multi Option in Types of Remote Connnections}.
21318
d9b1a651 21319@cindex @option{--debug}, @code{gdbserver} option
62709adf 21320The @option{--debug} option tells @code{gdbserver} to display extra
d9b1a651
EZ
21321status information about the debugging process.
21322@cindex @option{--remote-debug}, @code{gdbserver} option
21323The @option{--remote-debug} option tells @code{gdbserver} to display
62709adf
PA
21324remote protocol debug output. These options are intended for
21325@code{gdbserver} development and for bug reports to the developers.
2d717e4f 21326
87ce2a04
DE
21327@cindex @option{--debug-format}, @code{gdbserver} option
21328The @option{--debug-format=option1[,option2,...]} option tells
21329@code{gdbserver} to include additional information in each output.
21330Possible options are:
21331
21332@table @code
21333@item none
21334Turn off all extra information in debugging output.
21335@item all
21336Turn on all extra information in debugging output.
21337@item timestamps
21338Include a timestamp in each line of debugging output.
21339@end table
21340
21341Options are processed in order. Thus, for example, if @option{none}
21342appears last then no additional information is added to debugging output.
21343
d9b1a651 21344@cindex @option{--wrapper}, @code{gdbserver} option
ccd213ac
DJ
21345The @option{--wrapper} option specifies a wrapper to launch programs
21346for debugging. The option should be followed by the name of the
21347wrapper, then any command-line arguments to pass to the wrapper, then
21348@kbd{--} indicating the end of the wrapper arguments.
21349
21350@code{gdbserver} runs the specified wrapper program with a combined
21351command line including the wrapper arguments, then the name of the
21352program to debug, then any arguments to the program. The wrapper
21353runs until it executes your program, and then @value{GDBN} gains control.
21354
21355You can use any program that eventually calls @code{execve} with
21356its arguments as a wrapper. Several standard Unix utilities do
21357this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending
21358with @code{exec "$@@"} will also work.
21359
21360For example, you can use @code{env} to pass an environment variable to
21361the debugged program, without setting the variable in @code{gdbserver}'s
21362environment:
21363
21364@smallexample
21365$ gdbserver --wrapper env LD_PRELOAD=libtest.so -- :2222 ./testprog
21366@end smallexample
21367
6d580b63
YQ
21368@cindex @option{--selftest}
21369The @option{--selftest} option runs the self tests in @code{gdbserver}:
21370
21371@smallexample
21372$ gdbserver --selftest
21373Ran 2 unit tests, 0 failed
21374@end smallexample
21375
21376These tests are disabled in release.
2d717e4f
DJ
21377@subsection Connecting to @code{gdbserver}
21378
19d9d4ef
DB
21379The basic procedure for connecting to the remote target is:
21380@itemize
2d717e4f 21381
19d9d4ef
DB
21382@item
21383Run @value{GDBN} on the host system.
f822c95b 21384
19d9d4ef
DB
21385@item
21386Make sure you have the necessary symbol files
21387(@pxref{Host and target files}).
21388Load symbols for your application using the @code{file} command before you
21389connect. Use @code{set sysroot} to locate target libraries (unless your
21390@value{GDBN} was compiled with the correct sysroot using
21391@code{--with-sysroot}).
f822c95b 21392
19d9d4ef 21393@item
79a6e687 21394Connect to your target (@pxref{Connecting,,Connecting to a Remote Target}).
6f05cf9f 21395For TCP connections, you must start up @code{gdbserver} prior to using
19d9d4ef 21396the @code{target} command. Otherwise you may get an error whose
6f05cf9f 21397text depends on the host system, but which usually looks something like
2d717e4f 21398@samp{Connection refused}. Don't use the @code{load}
19d9d4ef
DB
21399command in @value{GDBN} when using @code{target remote} mode, since the
21400program is already on the target.
21401
21402@end itemize
07f31aa6 21403
19d9d4ef 21404@anchor{Monitor Commands for gdbserver}
79a6e687 21405@subsection Monitor Commands for @code{gdbserver}
c74d0ad8
DJ
21406@cindex monitor commands, for @code{gdbserver}
21407
21408During a @value{GDBN} session using @code{gdbserver}, you can use the
21409@code{monitor} command to send special requests to @code{gdbserver}.
2d717e4f 21410Here are the available commands.
c74d0ad8
DJ
21411
21412@table @code
21413@item monitor help
21414List the available monitor commands.
21415
21416@item monitor set debug 0
21417@itemx monitor set debug 1
21418Disable or enable general debugging messages.
21419
21420@item monitor set remote-debug 0
21421@itemx monitor set remote-debug 1
21422Disable or enable specific debugging messages associated with the remote
21423protocol (@pxref{Remote Protocol}).
21424
87ce2a04
DE
21425@item monitor set debug-format option1@r{[},option2,...@r{]}
21426Specify additional text to add to debugging messages.
21427Possible options are:
21428
21429@table @code
21430@item none
21431Turn off all extra information in debugging output.
21432@item all
21433Turn on all extra information in debugging output.
21434@item timestamps
21435Include a timestamp in each line of debugging output.
21436@end table
21437
21438Options are processed in order. Thus, for example, if @option{none}
21439appears last then no additional information is added to debugging output.
21440
cdbfd419
PP
21441@item monitor set libthread-db-search-path [PATH]
21442@cindex gdbserver, search path for @code{libthread_db}
21443When this command is issued, @var{path} is a colon-separated list of
21444directories to search for @code{libthread_db} (@pxref{Threads,,set
21445libthread-db-search-path}). If you omit @var{path},
84e578fb 21446@samp{libthread-db-search-path} will be reset to its default value.
cdbfd419 21447
98a5dd13
DE
21448The special entry @samp{$pdir} for @samp{libthread-db-search-path} is
21449not supported in @code{gdbserver}.
21450
2d717e4f
DJ
21451@item monitor exit
21452Tell gdbserver to exit immediately. This command should be followed by
21453@code{disconnect} to close the debugging session. @code{gdbserver} will
21454detach from any attached processes and kill any processes it created.
21455Use @code{monitor exit} to terminate @code{gdbserver} at the end
21456of a multi-process mode debug session.
21457
c74d0ad8
DJ
21458@end table
21459
fa593d66
PA
21460@subsection Tracepoints support in @code{gdbserver}
21461@cindex tracepoints support in @code{gdbserver}
21462
0fb4aa4b
PA
21463On some targets, @code{gdbserver} supports tracepoints, fast
21464tracepoints and static tracepoints.
fa593d66 21465
0fb4aa4b 21466For fast or static tracepoints to work, a special library called the
fa593d66
PA
21467@dfn{in-process agent} (IPA), must be loaded in the inferior process.
21468This library is built and distributed as an integral part of
0fb4aa4b
PA
21469@code{gdbserver}. In addition, support for static tracepoints
21470requires building the in-process agent library with static tracepoints
21471support. At present, the UST (LTTng Userspace Tracer,
21472@url{http://lttng.org/ust}) tracing engine is supported. This support
21473is automatically available if UST development headers are found in the
21474standard include path when @code{gdbserver} is built, or if
21475@code{gdbserver} was explicitly configured using @option{--with-ust}
21476to point at such headers. You can explicitly disable the support
21477using @option{--with-ust=no}.
fa593d66
PA
21478
21479There are several ways to load the in-process agent in your program:
21480
21481@table @code
21482@item Specifying it as dependency at link time
21483
21484You can link your program dynamically with the in-process agent
21485library. On most systems, this is accomplished by adding
21486@code{-linproctrace} to the link command.
21487
21488@item Using the system's preloading mechanisms
21489
21490You can force loading the in-process agent at startup time by using
21491your system's support for preloading shared libraries. Many Unixes
21492support the concept of preloading user defined libraries. In most
21493cases, you do that by specifying @code{LD_PRELOAD=libinproctrace.so}
21494in the environment. See also the description of @code{gdbserver}'s
21495@option{--wrapper} command line option.
21496
21497@item Using @value{GDBN} to force loading the agent at run time
21498
21499On some systems, you can force the inferior to load a shared library,
21500by calling a dynamic loader function in the inferior that takes care
21501of dynamically looking up and loading a shared library. On most Unix
21502systems, the function is @code{dlopen}. You'll use the @code{call}
21503command for that. For example:
21504
21505@smallexample
21506(@value{GDBP}) call dlopen ("libinproctrace.so", ...)
21507@end smallexample
21508
21509Note that on most Unix systems, for the @code{dlopen} function to be
21510available, the program needs to be linked with @code{-ldl}.
21511@end table
21512
21513On systems that have a userspace dynamic loader, like most Unix
21514systems, when you connect to @code{gdbserver} using @code{target
21515remote}, you'll find that the program is stopped at the dynamic
21516loader's entry point, and no shared library has been loaded in the
21517program's address space yet, including the in-process agent. In that
0fb4aa4b
PA
21518case, before being able to use any of the fast or static tracepoints
21519features, you need to let the loader run and load the shared
21520libraries. The simplest way to do that is to run the program to the
21521main procedure. E.g., if debugging a C or C@t{++} program, start
fa593d66
PA
21522@code{gdbserver} like so:
21523
21524@smallexample
21525$ gdbserver :9999 myprogram
21526@end smallexample
21527
21528Start GDB and connect to @code{gdbserver} like so, and run to main:
21529
21530@smallexample
21531$ gdb myprogram
21532(@value{GDBP}) target remote myhost:9999
215330x00007f215893ba60 in ?? () from /lib64/ld-linux-x86-64.so.2
21534(@value{GDBP}) b main
21535(@value{GDBP}) continue
21536@end smallexample
21537
21538The in-process tracing agent library should now be loaded into the
21539process; you can confirm it with the @code{info sharedlibrary}
21540command, which will list @file{libinproctrace.so} as loaded in the
0fb4aa4b
PA
21541process. You are now ready to install fast tracepoints, list static
21542tracepoint markers, probe static tracepoints markers, and start
fa593d66
PA
21543tracing.
21544
79a6e687
BW
21545@node Remote Configuration
21546@section Remote Configuration
501eef12 21547
9c16f35a
EZ
21548@kindex set remote
21549@kindex show remote
21550This section documents the configuration options available when
21551debugging remote programs. For the options related to the File I/O
fc320d37 21552extensions of the remote protocol, see @ref{system,
9c16f35a 21553system-call-allowed}.
501eef12
AC
21554
21555@table @code
9c16f35a 21556@item set remoteaddresssize @var{bits}
d3e8051b 21557@cindex address size for remote targets
9c16f35a
EZ
21558@cindex bits in remote address
21559Set the maximum size of address in a memory packet to the specified
21560number of bits. @value{GDBN} will mask off the address bits above
21561that number, when it passes addresses to the remote target. The
21562default value is the number of bits in the target's address.
21563
21564@item show remoteaddresssize
21565Show the current value of remote address size in bits.
21566
0d12017b 21567@item set serial baud @var{n}
9c16f35a
EZ
21568@cindex baud rate for remote targets
21569Set the baud rate for the remote serial I/O to @var{n} baud. The
21570value is used to set the speed of the serial port used for debugging
21571remote targets.
21572
0d12017b 21573@item show serial baud
9c16f35a
EZ
21574Show the current speed of the remote connection.
21575
236af5e3
YG
21576@item set serial parity @var{parity}
21577Set the parity for the remote serial I/O. Supported values of @var{parity} are:
21578@code{even}, @code{none}, and @code{odd}. The default is @code{none}.
21579
21580@item show serial parity
21581Show the current parity of the serial port.
21582
9c16f35a
EZ
21583@item set remotebreak
21584@cindex interrupt remote programs
21585@cindex BREAK signal instead of Ctrl-C
9a6253be 21586@anchor{set remotebreak}
9c16f35a 21587If set to on, @value{GDBN} sends a @code{BREAK} signal to the remote
c8aa23ab 21588when you type @kbd{Ctrl-c} to interrupt the program running
9a7a1b36 21589on the remote. If set to off, @value{GDBN} sends the @samp{Ctrl-C}
9c16f35a
EZ
21590character instead. The default is off, since most remote systems
21591expect to see @samp{Ctrl-C} as the interrupt signal.
21592
21593@item show remotebreak
21594Show whether @value{GDBN} sends @code{BREAK} or @samp{Ctrl-C} to
21595interrupt the remote program.
21596
23776285
MR
21597@item set remoteflow on
21598@itemx set remoteflow off
21599@kindex set remoteflow
21600Enable or disable hardware flow control (@code{RTS}/@code{CTS})
21601on the serial port used to communicate to the remote target.
21602
21603@item show remoteflow
21604@kindex show remoteflow
21605Show the current setting of hardware flow control.
21606
9c16f35a
EZ
21607@item set remotelogbase @var{base}
21608Set the base (a.k.a.@: radix) of logging serial protocol
21609communications to @var{base}. Supported values of @var{base} are:
21610@code{ascii}, @code{octal}, and @code{hex}. The default is
21611@code{ascii}.
21612
21613@item show remotelogbase
21614Show the current setting of the radix for logging remote serial
21615protocol.
21616
21617@item set remotelogfile @var{file}
21618@cindex record serial communications on file
21619Record remote serial communications on the named @var{file}. The
21620default is not to record at all.
21621
2d8b6830 21622@item show remotelogfile
9c16f35a
EZ
21623Show the current setting of the file name on which to record the
21624serial communications.
21625
21626@item set remotetimeout @var{num}
21627@cindex timeout for serial communications
21628@cindex remote timeout
21629Set the timeout limit to wait for the remote target to respond to
21630@var{num} seconds. The default is 2 seconds.
21631
21632@item show remotetimeout
21633Show the current number of seconds to wait for the remote target
21634responses.
21635
21636@cindex limit hardware breakpoints and watchpoints
21637@cindex remote target, limit break- and watchpoints
501eef12
AC
21638@anchor{set remote hardware-watchpoint-limit}
21639@anchor{set remote hardware-breakpoint-limit}
21640@item set remote hardware-watchpoint-limit @var{limit}
21641@itemx set remote hardware-breakpoint-limit @var{limit}
055303e2
AB
21642Restrict @value{GDBN} to using @var{limit} remote hardware watchpoints
21643or breakpoints. The @var{limit} can be set to 0 to disable hardware
21644watchpoints or breakpoints, and @code{unlimited} for unlimited
21645watchpoints or breakpoints.
21646
21647@item show remote hardware-watchpoint-limit
21648@itemx show remote hardware-breakpoint-limit
21649Show the current limit for the number of hardware watchpoints or
21650breakpoints that @value{GDBN} can use.
2d717e4f 21651
480a3f21
PW
21652@cindex limit hardware watchpoints length
21653@cindex remote target, limit watchpoints length
21654@anchor{set remote hardware-watchpoint-length-limit}
21655@item set remote hardware-watchpoint-length-limit @var{limit}
055303e2
AB
21656Restrict @value{GDBN} to using @var{limit} bytes for the maximum
21657length of a remote hardware watchpoint. A @var{limit} of 0 disables
21658hardware watchpoints and @code{unlimited} allows watchpoints of any
21659length.
480a3f21
PW
21660
21661@item show remote hardware-watchpoint-length-limit
21662Show the current limit (in bytes) of the maximum length of
21663a remote hardware watchpoint.
21664
2d717e4f
DJ
21665@item set remote exec-file @var{filename}
21666@itemx show remote exec-file
21667@anchor{set remote exec-file}
21668@cindex executable file, for remote target
21669Select the file used for @code{run} with @code{target
21670extended-remote}. This should be set to a filename valid on the
21671target system. If it is not set, the target will use a default
21672filename (e.g.@: the last program run).
84603566 21673
9a7071a8
JB
21674@item set remote interrupt-sequence
21675@cindex interrupt remote programs
21676@cindex select Ctrl-C, BREAK or BREAK-g
21677Allow the user to select one of @samp{Ctrl-C}, a @code{BREAK} or
21678@samp{BREAK-g} as the
21679sequence to the remote target in order to interrupt the execution.
21680@samp{Ctrl-C} is a default. Some system prefers @code{BREAK} which
21681is high level of serial line for some certain time.
21682Linux kernel prefers @samp{BREAK-g}, a.k.a Magic SysRq g.
21683It is @code{BREAK} signal followed by character @code{g}.
21684
21685@item show interrupt-sequence
21686Show which of @samp{Ctrl-C}, @code{BREAK} or @code{BREAK-g}
21687is sent by @value{GDBN} to interrupt the remote program.
21688@code{BREAK-g} is BREAK signal followed by @code{g} and
21689also known as Magic SysRq g.
21690
21691@item set remote interrupt-on-connect
21692@cindex send interrupt-sequence on start
21693Specify whether interrupt-sequence is sent to remote target when
21694@value{GDBN} connects to it. This is mostly needed when you debug
21695Linux kernel. Linux kernel expects @code{BREAK} followed by @code{g}
21696which is known as Magic SysRq g in order to connect @value{GDBN}.
21697
21698@item show interrupt-on-connect
21699Show whether interrupt-sequence is sent
21700to remote target when @value{GDBN} connects to it.
21701
84603566
SL
21702@kindex set tcp
21703@kindex show tcp
21704@item set tcp auto-retry on
21705@cindex auto-retry, for remote TCP target
21706Enable auto-retry for remote TCP connections. This is useful if the remote
21707debugging agent is launched in parallel with @value{GDBN}; there is a race
21708condition because the agent may not become ready to accept the connection
21709before @value{GDBN} attempts to connect. When auto-retry is
21710enabled, if the initial attempt to connect fails, @value{GDBN} reattempts
21711to establish the connection using the timeout specified by
21712@code{set tcp connect-timeout}.
21713
21714@item set tcp auto-retry off
21715Do not auto-retry failed TCP connections.
21716
21717@item show tcp auto-retry
21718Show the current auto-retry setting.
21719
21720@item set tcp connect-timeout @var{seconds}
f81d1120 21721@itemx set tcp connect-timeout unlimited
84603566
SL
21722@cindex connection timeout, for remote TCP target
21723@cindex timeout, for remote target connection
21724Set the timeout for establishing a TCP connection to the remote target to
21725@var{seconds}. The timeout affects both polling to retry failed connections
21726(enabled by @code{set tcp auto-retry on}) and waiting for connections
21727that are merely slow to complete, and represents an approximate cumulative
f81d1120
PA
21728value. If @var{seconds} is @code{unlimited}, there is no timeout and
21729@value{GDBN} will keep attempting to establish a connection forever,
21730unless interrupted with @kbd{Ctrl-c}. The default is 15 seconds.
84603566
SL
21731
21732@item show tcp connect-timeout
21733Show the current connection timeout setting.
501eef12
AC
21734@end table
21735
427c3a89
DJ
21736@cindex remote packets, enabling and disabling
21737The @value{GDBN} remote protocol autodetects the packets supported by
21738your debugging stub. If you need to override the autodetection, you
21739can use these commands to enable or disable individual packets. Each
21740packet can be set to @samp{on} (the remote target supports this
21741packet), @samp{off} (the remote target does not support this packet),
21742or @samp{auto} (detect remote target support for this packet). They
21743all default to @samp{auto}. For more information about each packet,
21744see @ref{Remote Protocol}.
21745
21746During normal use, you should not have to use any of these commands.
21747If you do, that may be a bug in your remote debugging stub, or a bug
21748in @value{GDBN}. You may want to report the problem to the
21749@value{GDBN} developers.
21750
cfa9d6d9
DJ
21751For each packet @var{name}, the command to enable or disable the
21752packet is @code{set remote @var{name}-packet}. The available settings
21753are:
427c3a89 21754
cfa9d6d9 21755@multitable @columnfractions 0.28 0.32 0.25
427c3a89
DJ
21756@item Command Name
21757@tab Remote Packet
21758@tab Related Features
21759
cfa9d6d9 21760@item @code{fetch-register}
427c3a89
DJ
21761@tab @code{p}
21762@tab @code{info registers}
21763
cfa9d6d9 21764@item @code{set-register}
427c3a89
DJ
21765@tab @code{P}
21766@tab @code{set}
21767
cfa9d6d9 21768@item @code{binary-download}
427c3a89
DJ
21769@tab @code{X}
21770@tab @code{load}, @code{set}
21771
cfa9d6d9 21772@item @code{read-aux-vector}
427c3a89
DJ
21773@tab @code{qXfer:auxv:read}
21774@tab @code{info auxv}
21775
cfa9d6d9 21776@item @code{symbol-lookup}
427c3a89
DJ
21777@tab @code{qSymbol}
21778@tab Detecting multiple threads
21779
2d717e4f
DJ
21780@item @code{attach}
21781@tab @code{vAttach}
21782@tab @code{attach}
21783
cfa9d6d9 21784@item @code{verbose-resume}
427c3a89
DJ
21785@tab @code{vCont}
21786@tab Stepping or resuming multiple threads
21787
2d717e4f
DJ
21788@item @code{run}
21789@tab @code{vRun}
21790@tab @code{run}
21791
cfa9d6d9 21792@item @code{software-breakpoint}
427c3a89
DJ
21793@tab @code{Z0}
21794@tab @code{break}
21795
cfa9d6d9 21796@item @code{hardware-breakpoint}
427c3a89
DJ
21797@tab @code{Z1}
21798@tab @code{hbreak}
21799
cfa9d6d9 21800@item @code{write-watchpoint}
427c3a89
DJ
21801@tab @code{Z2}
21802@tab @code{watch}
21803
cfa9d6d9 21804@item @code{read-watchpoint}
427c3a89
DJ
21805@tab @code{Z3}
21806@tab @code{rwatch}
21807
cfa9d6d9 21808@item @code{access-watchpoint}
427c3a89
DJ
21809@tab @code{Z4}
21810@tab @code{awatch}
21811
c78fa86a
GB
21812@item @code{pid-to-exec-file}
21813@tab @code{qXfer:exec-file:read}
21814@tab @code{attach}, @code{run}
21815
cfa9d6d9
DJ
21816@item @code{target-features}
21817@tab @code{qXfer:features:read}
21818@tab @code{set architecture}
21819
21820@item @code{library-info}
21821@tab @code{qXfer:libraries:read}
21822@tab @code{info sharedlibrary}
21823
21824@item @code{memory-map}
21825@tab @code{qXfer:memory-map:read}
21826@tab @code{info mem}
21827
0fb4aa4b
PA
21828@item @code{read-sdata-object}
21829@tab @code{qXfer:sdata:read}
21830@tab @code{print $_sdata}
21831
cfa9d6d9
DJ
21832@item @code{read-spu-object}
21833@tab @code{qXfer:spu:read}
21834@tab @code{info spu}
21835
21836@item @code{write-spu-object}
21837@tab @code{qXfer:spu:write}
21838@tab @code{info spu}
21839
4aa995e1
PA
21840@item @code{read-siginfo-object}
21841@tab @code{qXfer:siginfo:read}
21842@tab @code{print $_siginfo}
21843
21844@item @code{write-siginfo-object}
21845@tab @code{qXfer:siginfo:write}
21846@tab @code{set $_siginfo}
21847
dc146f7c
VP
21848@item @code{threads}
21849@tab @code{qXfer:threads:read}
21850@tab @code{info threads}
21851
cfa9d6d9 21852@item @code{get-thread-local-@*storage-address}
427c3a89
DJ
21853@tab @code{qGetTLSAddr}
21854@tab Displaying @code{__thread} variables
21855
711e434b
PM
21856@item @code{get-thread-information-block-address}
21857@tab @code{qGetTIBAddr}
21858@tab Display MS-Windows Thread Information Block.
21859
08388c79
DE
21860@item @code{search-memory}
21861@tab @code{qSearch:memory}
21862@tab @code{find}
21863
427c3a89
DJ
21864@item @code{supported-packets}
21865@tab @code{qSupported}
21866@tab Remote communications parameters
21867
82075af2
JS
21868@item @code{catch-syscalls}
21869@tab @code{QCatchSyscalls}
21870@tab @code{catch syscall}
21871
cfa9d6d9 21872@item @code{pass-signals}
89be2091
DJ
21873@tab @code{QPassSignals}
21874@tab @code{handle @var{signal}}
21875
9b224c5e
PA
21876@item @code{program-signals}
21877@tab @code{QProgramSignals}
21878@tab @code{handle @var{signal}}
21879
a6b151f1
DJ
21880@item @code{hostio-close-packet}
21881@tab @code{vFile:close}
21882@tab @code{remote get}, @code{remote put}
21883
21884@item @code{hostio-open-packet}
21885@tab @code{vFile:open}
21886@tab @code{remote get}, @code{remote put}
21887
21888@item @code{hostio-pread-packet}
21889@tab @code{vFile:pread}
21890@tab @code{remote get}, @code{remote put}
21891
21892@item @code{hostio-pwrite-packet}
21893@tab @code{vFile:pwrite}
21894@tab @code{remote get}, @code{remote put}
21895
21896@item @code{hostio-unlink-packet}
21897@tab @code{vFile:unlink}
21898@tab @code{remote delete}
a6f3e723 21899
b9e7b9c3
UW
21900@item @code{hostio-readlink-packet}
21901@tab @code{vFile:readlink}
21902@tab Host I/O
21903
0a93529c
GB
21904@item @code{hostio-fstat-packet}
21905@tab @code{vFile:fstat}
21906@tab Host I/O
21907
15a201c8
GB
21908@item @code{hostio-setfs-packet}
21909@tab @code{vFile:setfs}
21910@tab Host I/O
21911
a6f3e723
SL
21912@item @code{noack-packet}
21913@tab @code{QStartNoAckMode}
21914@tab Packet acknowledgment
07e059b5
VP
21915
21916@item @code{osdata}
21917@tab @code{qXfer:osdata:read}
21918@tab @code{info os}
0b16c5cf
PA
21919
21920@item @code{query-attached}
21921@tab @code{qAttached}
21922@tab Querying remote process attach state.
b3b9301e 21923
a46c1e42
PA
21924@item @code{trace-buffer-size}
21925@tab @code{QTBuffer:size}
21926@tab @code{set trace-buffer-size}
21927
bd3eecc3
PA
21928@item @code{trace-status}
21929@tab @code{qTStatus}
21930@tab @code{tstatus}
21931
b3b9301e
PA
21932@item @code{traceframe-info}
21933@tab @code{qXfer:traceframe-info:read}
21934@tab Traceframe info
03583c20 21935
1e4d1764
YQ
21936@item @code{install-in-trace}
21937@tab @code{InstallInTrace}
21938@tab Install tracepoint in tracing
21939
03583c20
UW
21940@item @code{disable-randomization}
21941@tab @code{QDisableRandomization}
21942@tab @code{set disable-randomization}
83364271 21943
aefd8b33
SDJ
21944@item @code{startup-with-shell}
21945@tab @code{QStartupWithShell}
21946@tab @code{set startup-with-shell}
21947
0a2dde4a
SDJ
21948@item @code{environment-hex-encoded}
21949@tab @code{QEnvironmentHexEncoded}
21950@tab @code{set environment}
21951
21952@item @code{environment-unset}
21953@tab @code{QEnvironmentUnset}
21954@tab @code{unset environment}
21955
21956@item @code{environment-reset}
21957@tab @code{QEnvironmentReset}
21958@tab @code{Reset the inferior environment (i.e., unset user-set variables)}
21959
bc3b087d
SDJ
21960@item @code{set-working-dir}
21961@tab @code{QSetWorkingDir}
21962@tab @code{set cwd}
21963
83364271
LM
21964@item @code{conditional-breakpoints-packet}
21965@tab @code{Z0 and Z1}
21966@tab @code{Support for target-side breakpoint condition evaluation}
f7e6eed5 21967
73b8c1fd
PA
21968@item @code{multiprocess-extensions}
21969@tab @code{multiprocess extensions}
21970@tab Debug multiple processes and remote process PID awareness
21971
f7e6eed5
PA
21972@item @code{swbreak-feature}
21973@tab @code{swbreak stop reason}
21974@tab @code{break}
21975
21976@item @code{hwbreak-feature}
21977@tab @code{hwbreak stop reason}
21978@tab @code{hbreak}
21979
0d71eef5
DB
21980@item @code{fork-event-feature}
21981@tab @code{fork stop reason}
21982@tab @code{fork}
21983
21984@item @code{vfork-event-feature}
21985@tab @code{vfork stop reason}
21986@tab @code{vfork}
21987
b459a59b
DB
21988@item @code{exec-event-feature}
21989@tab @code{exec stop reason}
21990@tab @code{exec}
21991
65706a29
PA
21992@item @code{thread-events}
21993@tab @code{QThreadEvents}
21994@tab Tracking thread lifetime.
21995
f2faf941
PA
21996@item @code{no-resumed-stop-reply}
21997@tab @code{no resumed thread left stop reply}
21998@tab Tracking thread lifetime.
21999
427c3a89
DJ
22000@end multitable
22001
79a6e687
BW
22002@node Remote Stub
22003@section Implementing a Remote Stub
7a292a7a 22004
8e04817f
AC
22005@cindex debugging stub, example
22006@cindex remote stub, example
22007@cindex stub example, remote debugging
22008The stub files provided with @value{GDBN} implement the target side of the
22009communication protocol, and the @value{GDBN} side is implemented in the
22010@value{GDBN} source file @file{remote.c}. Normally, you can simply allow
22011these subroutines to communicate, and ignore the details. (If you're
22012implementing your own stub file, you can still ignore the details: start
22013with one of the existing stub files. @file{sparc-stub.c} is the best
22014organized, and therefore the easiest to read.)
22015
104c1213
JM
22016@cindex remote serial debugging, overview
22017To debug a program running on another machine (the debugging
22018@dfn{target} machine), you must first arrange for all the usual
22019prerequisites for the program to run by itself. For example, for a C
22020program, you need:
c906108c 22021
104c1213
JM
22022@enumerate
22023@item
22024A startup routine to set up the C runtime environment; these usually
22025have a name like @file{crt0}. The startup routine may be supplied by
22026your hardware supplier, or you may have to write your own.
96baa820 22027
5d161b24 22028@item
d4f3574e 22029A C subroutine library to support your program's
104c1213 22030subroutine calls, notably managing input and output.
96baa820 22031
104c1213
JM
22032@item
22033A way of getting your program to the other machine---for example, a
22034download program. These are often supplied by the hardware
22035manufacturer, but you may have to write your own from hardware
22036documentation.
22037@end enumerate
96baa820 22038
104c1213
JM
22039The next step is to arrange for your program to use a serial port to
22040communicate with the machine where @value{GDBN} is running (the @dfn{host}
22041machine). In general terms, the scheme looks like this:
96baa820 22042
104c1213
JM
22043@table @emph
22044@item On the host,
22045@value{GDBN} already understands how to use this protocol; when everything
22046else is set up, you can simply use the @samp{target remote} command
22047(@pxref{Targets,,Specifying a Debugging Target}).
22048
22049@item On the target,
22050you must link with your program a few special-purpose subroutines that
22051implement the @value{GDBN} remote serial protocol. The file containing these
22052subroutines is called a @dfn{debugging stub}.
22053
22054On certain remote targets, you can use an auxiliary program
22055@code{gdbserver} instead of linking a stub into your program.
79a6e687 22056@xref{Server,,Using the @code{gdbserver} Program}, for details.
104c1213 22057@end table
96baa820 22058
104c1213
JM
22059The debugging stub is specific to the architecture of the remote
22060machine; for example, use @file{sparc-stub.c} to debug programs on
22061@sc{sparc} boards.
96baa820 22062
104c1213
JM
22063@cindex remote serial stub list
22064These working remote stubs are distributed with @value{GDBN}:
96baa820 22065
104c1213
JM
22066@table @code
22067
22068@item i386-stub.c
41afff9a 22069@cindex @file{i386-stub.c}
104c1213
JM
22070@cindex Intel
22071@cindex i386
22072For Intel 386 and compatible architectures.
22073
22074@item m68k-stub.c
41afff9a 22075@cindex @file{m68k-stub.c}
104c1213
JM
22076@cindex Motorola 680x0
22077@cindex m680x0
22078For Motorola 680x0 architectures.
22079
22080@item sh-stub.c
41afff9a 22081@cindex @file{sh-stub.c}
172c2a43 22082@cindex Renesas
104c1213 22083@cindex SH
172c2a43 22084For Renesas SH architectures.
104c1213
JM
22085
22086@item sparc-stub.c
41afff9a 22087@cindex @file{sparc-stub.c}
104c1213
JM
22088@cindex Sparc
22089For @sc{sparc} architectures.
22090
22091@item sparcl-stub.c
41afff9a 22092@cindex @file{sparcl-stub.c}
104c1213
JM
22093@cindex Fujitsu
22094@cindex SparcLite
22095For Fujitsu @sc{sparclite} architectures.
22096
22097@end table
22098
22099The @file{README} file in the @value{GDBN} distribution may list other
22100recently added stubs.
22101
22102@menu
22103* Stub Contents:: What the stub can do for you
22104* Bootstrapping:: What you must do for the stub
22105* Debug Session:: Putting it all together
104c1213
JM
22106@end menu
22107
6d2ebf8b 22108@node Stub Contents
79a6e687 22109@subsection What the Stub Can Do for You
104c1213
JM
22110
22111@cindex remote serial stub
22112The debugging stub for your architecture supplies these three
22113subroutines:
22114
22115@table @code
22116@item set_debug_traps
4644b6e3 22117@findex set_debug_traps
104c1213
JM
22118@cindex remote serial stub, initialization
22119This routine arranges for @code{handle_exception} to run when your
2fb860fc
PA
22120program stops. You must call this subroutine explicitly in your
22121program's startup code.
104c1213
JM
22122
22123@item handle_exception
4644b6e3 22124@findex handle_exception
104c1213
JM
22125@cindex remote serial stub, main routine
22126This is the central workhorse, but your program never calls it
22127explicitly---the setup code arranges for @code{handle_exception} to
22128run when a trap is triggered.
22129
22130@code{handle_exception} takes control when your program stops during
22131execution (for example, on a breakpoint), and mediates communications
22132with @value{GDBN} on the host machine. This is where the communications
22133protocol is implemented; @code{handle_exception} acts as the @value{GDBN}
d4f3574e 22134representative on the target machine. It begins by sending summary
104c1213
JM
22135information on the state of your program, then continues to execute,
22136retrieving and transmitting any information @value{GDBN} needs, until you
22137execute a @value{GDBN} command that makes your program resume; at that point,
22138@code{handle_exception} returns control to your own code on the target
5d161b24 22139machine.
104c1213
JM
22140
22141@item breakpoint
22142@cindex @code{breakpoint} subroutine, remote
22143Use this auxiliary subroutine to make your program contain a
22144breakpoint. Depending on the particular situation, this may be the only
22145way for @value{GDBN} to get control. For instance, if your target
22146machine has some sort of interrupt button, you won't need to call this;
22147pressing the interrupt button transfers control to
22148@code{handle_exception}---in effect, to @value{GDBN}. On some machines,
22149simply receiving characters on the serial port may also trigger a trap;
22150again, in that situation, you don't need to call @code{breakpoint} from
22151your own program---simply running @samp{target remote} from the host
5d161b24 22152@value{GDBN} session gets control.
104c1213
JM
22153
22154Call @code{breakpoint} if none of these is true, or if you simply want
22155to make certain your program stops at a predetermined point for the
22156start of your debugging session.
22157@end table
22158
6d2ebf8b 22159@node Bootstrapping
79a6e687 22160@subsection What You Must Do for the Stub
104c1213
JM
22161
22162@cindex remote stub, support routines
22163The debugging stubs that come with @value{GDBN} are set up for a particular
22164chip architecture, but they have no information about the rest of your
22165debugging target machine.
22166
22167First of all you need to tell the stub how to communicate with the
22168serial port.
22169
22170@table @code
22171@item int getDebugChar()
4644b6e3 22172@findex getDebugChar
104c1213
JM
22173Write this subroutine to read a single character from the serial port.
22174It may be identical to @code{getchar} for your target system; a
22175different name is used to allow you to distinguish the two if you wish.
22176
22177@item void putDebugChar(int)
4644b6e3 22178@findex putDebugChar
104c1213 22179Write this subroutine to write a single character to the serial port.
5d161b24 22180It may be identical to @code{putchar} for your target system; a
104c1213
JM
22181different name is used to allow you to distinguish the two if you wish.
22182@end table
22183
22184@cindex control C, and remote debugging
22185@cindex interrupting remote targets
22186If you want @value{GDBN} to be able to stop your program while it is
22187running, you need to use an interrupt-driven serial driver, and arrange
22188for it to stop when it receives a @code{^C} (@samp{\003}, the control-C
22189character). That is the character which @value{GDBN} uses to tell the
22190remote system to stop.
22191
22192Getting the debugging target to return the proper status to @value{GDBN}
22193probably requires changes to the standard stub; one quick and dirty way
22194is to just execute a breakpoint instruction (the ``dirty'' part is that
22195@value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}).
22196
22197Other routines you need to supply are:
22198
22199@table @code
22200@item void exceptionHandler (int @var{exception_number}, void *@var{exception_address})
4644b6e3 22201@findex exceptionHandler
104c1213
JM
22202Write this function to install @var{exception_address} in the exception
22203handling tables. You need to do this because the stub does not have any
22204way of knowing what the exception handling tables on your target system
22205are like (for example, the processor's table might be in @sc{rom},
22206containing entries which point to a table in @sc{ram}).
697aa1b7 22207The @var{exception_number} specifies the exception which should be changed;
104c1213
JM
22208its meaning is architecture-dependent (for example, different numbers
22209might represent divide by zero, misaligned access, etc). When this
22210exception occurs, control should be transferred directly to
22211@var{exception_address}, and the processor state (stack, registers,
22212and so on) should be just as it is when a processor exception occurs. So if
22213you want to use a jump instruction to reach @var{exception_address}, it
22214should be a simple jump, not a jump to subroutine.
22215
22216For the 386, @var{exception_address} should be installed as an interrupt
22217gate so that interrupts are masked while the handler runs. The gate
22218should be at privilege level 0 (the most privileged level). The
22219@sc{sparc} and 68k stubs are able to mask interrupts themselves without
22220help from @code{exceptionHandler}.
22221
22222@item void flush_i_cache()
4644b6e3 22223@findex flush_i_cache
d4f3574e 22224On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the
104c1213
JM
22225instruction cache, if any, on your target machine. If there is no
22226instruction cache, this subroutine may be a no-op.
22227
22228On target machines that have instruction caches, @value{GDBN} requires this
22229function to make certain that the state of your program is stable.
22230@end table
22231
22232@noindent
22233You must also make sure this library routine is available:
22234
22235@table @code
22236@item void *memset(void *, int, int)
4644b6e3 22237@findex memset
104c1213
JM
22238This is the standard library function @code{memset} that sets an area of
22239memory to a known value. If you have one of the free versions of
22240@code{libc.a}, @code{memset} can be found there; otherwise, you must
22241either obtain it from your hardware manufacturer, or write your own.
22242@end table
22243
22244If you do not use the GNU C compiler, you may need other standard
22245library subroutines as well; this varies from one stub to another,
22246but in general the stubs are likely to use any of the common library
e22ea452 22247subroutines which @code{@value{NGCC}} generates as inline code.
104c1213
JM
22248
22249
6d2ebf8b 22250@node Debug Session
79a6e687 22251@subsection Putting it All Together
104c1213
JM
22252
22253@cindex remote serial debugging summary
22254In summary, when your program is ready to debug, you must follow these
22255steps.
22256
22257@enumerate
22258@item
6d2ebf8b 22259Make sure you have defined the supporting low-level routines
79a6e687 22260(@pxref{Bootstrapping,,What You Must Do for the Stub}):
104c1213
JM
22261@display
22262@code{getDebugChar}, @code{putDebugChar},
22263@code{flush_i_cache}, @code{memset}, @code{exceptionHandler}.
22264@end display
22265
22266@item
2fb860fc
PA
22267Insert these lines in your program's startup code, before the main
22268procedure is called:
104c1213 22269
474c8240 22270@smallexample
104c1213
JM
22271set_debug_traps();
22272breakpoint();
474c8240 22273@end smallexample
104c1213 22274
2fb860fc
PA
22275On some machines, when a breakpoint trap is raised, the hardware
22276automatically makes the PC point to the instruction after the
22277breakpoint. If your machine doesn't do that, you may need to adjust
22278@code{handle_exception} to arrange for it to return to the instruction
22279after the breakpoint on this first invocation, so that your program
22280doesn't keep hitting the initial breakpoint instead of making
22281progress.
22282
104c1213
JM
22283@item
22284For the 680x0 stub only, you need to provide a variable called
22285@code{exceptionHook}. Normally you just use:
22286
474c8240 22287@smallexample
104c1213 22288void (*exceptionHook)() = 0;
474c8240 22289@end smallexample
104c1213 22290
d4f3574e 22291@noindent
104c1213 22292but if before calling @code{set_debug_traps}, you set it to point to a
598ca718 22293function in your program, that function is called when
104c1213
JM
22294@code{@value{GDBN}} continues after stopping on a trap (for example, bus
22295error). The function indicated by @code{exceptionHook} is called with
22296one parameter: an @code{int} which is the exception number.
22297
22298@item
22299Compile and link together: your program, the @value{GDBN} debugging stub for
22300your target architecture, and the supporting subroutines.
22301
22302@item
22303Make sure you have a serial connection between your target machine and
22304the @value{GDBN} host, and identify the serial port on the host.
22305
22306@item
22307@c The "remote" target now provides a `load' command, so we should
22308@c document that. FIXME.
22309Download your program to your target machine (or get it there by
22310whatever means the manufacturer provides), and start it.
22311
22312@item
07f31aa6 22313Start @value{GDBN} on the host, and connect to the target
79a6e687 22314(@pxref{Connecting,,Connecting to a Remote Target}).
9db8d71f 22315
104c1213
JM
22316@end enumerate
22317
8e04817f
AC
22318@node Configurations
22319@chapter Configuration-Specific Information
104c1213 22320
8e04817f
AC
22321While nearly all @value{GDBN} commands are available for all native and
22322cross versions of the debugger, there are some exceptions. This chapter
22323describes things that are only available in certain configurations.
104c1213 22324
8e04817f
AC
22325There are three major categories of configurations: native
22326configurations, where the host and target are the same, embedded
22327operating system configurations, which are usually the same for several
22328different processor architectures, and bare embedded processors, which
22329are quite different from each other.
104c1213 22330
8e04817f
AC
22331@menu
22332* Native::
22333* Embedded OS::
22334* Embedded Processors::
22335* Architectures::
22336@end menu
104c1213 22337
8e04817f
AC
22338@node Native
22339@section Native
104c1213 22340
8e04817f
AC
22341This section describes details specific to particular native
22342configurations.
6cf7e474 22343
8e04817f 22344@menu
7561d450 22345* BSD libkvm Interface:: Debugging BSD kernel memory images
2d97a5d9 22346* Process Information:: Process information
8e04817f 22347* DJGPP Native:: Features specific to the DJGPP port
78c47bea 22348* Cygwin Native:: Features specific to the Cygwin port
14d6dd68 22349* Hurd Native:: Features specific to @sc{gnu} Hurd
a80b95ba 22350* Darwin:: Features specific to Darwin
e9076973 22351* FreeBSD:: Features specific to FreeBSD
8e04817f 22352@end menu
6cf7e474 22353
7561d450
MK
22354@node BSD libkvm Interface
22355@subsection BSD libkvm Interface
22356
22357@cindex libkvm
22358@cindex kernel memory image
22359@cindex kernel crash dump
22360
22361BSD-derived systems (FreeBSD/NetBSD/OpenBSD) have a kernel memory
22362interface that provides a uniform interface for accessing kernel virtual
22363memory images, including live systems and crash dumps. @value{GDBN}
22364uses this interface to allow you to debug live kernels and kernel crash
22365dumps on many native BSD configurations. This is implemented as a
22366special @code{kvm} debugging target. For debugging a live system, load
22367the currently running kernel into @value{GDBN} and connect to the
22368@code{kvm} target:
22369
22370@smallexample
22371(@value{GDBP}) @b{target kvm}
22372@end smallexample
22373
22374For debugging crash dumps, provide the file name of the crash dump as an
22375argument:
22376
22377@smallexample
22378(@value{GDBP}) @b{target kvm /var/crash/bsd.0}
22379@end smallexample
22380
22381Once connected to the @code{kvm} target, the following commands are
22382available:
22383
22384@table @code
22385@kindex kvm
22386@item kvm pcb
721c2651 22387Set current context from the @dfn{Process Control Block} (PCB) address.
7561d450
MK
22388
22389@item kvm proc
22390Set current context from proc address. This command isn't available on
22391modern FreeBSD systems.
22392@end table
22393
2d97a5d9
JB
22394@node Process Information
22395@subsection Process Information
60bf7e09
EZ
22396@cindex /proc
22397@cindex examine process image
22398@cindex process info via @file{/proc}
104c1213 22399
2d97a5d9
JB
22400Some operating systems provide interfaces to fetch additional
22401information about running processes beyond memory and per-thread
22402register state. If @value{GDBN} is configured for an operating system
22403with a supported interface, the command @code{info proc} is available
22404to report information about the process running your program, or about
22405any process running on your system.
451b7c33 22406
2d97a5d9
JB
22407One supported interface is a facility called @samp{/proc} that can be
22408used to examine the image of a running process using file-system
22409subroutines. This facility is supported on @sc{gnu}/Linux and Solaris
22410systems.
451b7c33 22411
2d97a5d9
JB
22412On FreeBSD systems, system control nodes are used to query process
22413information.
22414
22415In addition, some systems may provide additional process information
22416in core files. Note that a core file may include a subset of the
22417information available from a live process. Process information is
22418currently avaiable from cores created on @sc{gnu}/Linux and FreeBSD
22419systems.
104c1213 22420
8e04817f
AC
22421@table @code
22422@kindex info proc
60bf7e09 22423@cindex process ID
8e04817f 22424@item info proc
60bf7e09 22425@itemx info proc @var{process-id}
73f1bd76 22426Summarize available information about a process. If a
60bf7e09
EZ
22427process ID is specified by @var{process-id}, display information about
22428that process; otherwise display information about the program being
22429debugged. The summary includes the debugged process ID, the command
22430line used to invoke it, its current working directory, and its
22431executable file's absolute file name.
22432
22433On some systems, @var{process-id} can be of the form
22434@samp{[@var{pid}]/@var{tid}} which specifies a certain thread ID
22435within a process. If the optional @var{pid} part is missing, it means
22436a thread from the process being debugged (the leading @samp{/} still
22437needs to be present, or else @value{GDBN} will interpret the number as
22438a process ID rather than a thread ID).
6cf7e474 22439
0c631110
TT
22440@item info proc cmdline
22441@cindex info proc cmdline
22442Show the original command line of the process. This command is
2d97a5d9 22443supported on @sc{gnu}/Linux and FreeBSD.
0c631110
TT
22444
22445@item info proc cwd
22446@cindex info proc cwd
22447Show the current working directory of the process. This command is
2d97a5d9 22448supported on @sc{gnu}/Linux and FreeBSD.
0c631110
TT
22449
22450@item info proc exe
22451@cindex info proc exe
2d97a5d9
JB
22452Show the name of executable of the process. This command is supported
22453on @sc{gnu}/Linux and FreeBSD.
0c631110 22454
8b113111
JB
22455@item info proc files
22456@cindex info proc files
22457Show the file descriptors open by the process. For each open file
22458descriptor, @value{GDBN} shows its number, type (file, directory,
22459character device, socket), file pointer offset, and the name of the
22460resource open on the descriptor. The resource name can be a file name
22461(for files, directories, and devices) or a protocol followed by socket
22462address (for network connections). This command is supported on
22463FreeBSD.
22464
22465This example shows the open file descriptors for a process using a
22466tty for standard input and output as well as two network sockets:
22467
22468@smallexample
22469(gdb) info proc files 22136
22470process 22136
22471Open files:
22472
22473 FD Type Offset Flags Name
22474 text file - r-------- /usr/bin/ssh
22475 ctty chr - rw------- /dev/pts/20
22476 cwd dir - r-------- /usr/home/john
22477 root dir - r-------- /
22478 0 chr 0x32933a4 rw------- /dev/pts/20
22479 1 chr 0x32933a4 rw------- /dev/pts/20
22480 2 chr 0x32933a4 rw------- /dev/pts/20
22481 3 socket 0x0 rw----n-- tcp4 10.0.1.2:53014 -> 10.0.1.10:22
22482 4 socket 0x0 rw------- unix stream:/tmp/ssh-FIt89oAzOn5f/agent.2456
22483@end smallexample
22484
8e04817f 22485@item info proc mappings
60bf7e09 22486@cindex memory address space mappings
73f1bd76 22487Report the memory address space ranges accessible in a process. On
2d97a5d9
JB
22488Solaris and FreeBSD systems, each memory range includes information on
22489whether the process has read, write, or execute access rights to each
22490range. On @sc{gnu}/Linux and FreeBSD systems, each memory range
22491includes the object file which is mapped to that range.
60bf7e09
EZ
22492
22493@item info proc stat
22494@itemx info proc status
22495@cindex process detailed status information
2d97a5d9
JB
22496Show additional process-related information, including the user ID and
22497group ID; virtual memory usage; the signals that are pending, blocked,
22498and ignored; its TTY; its consumption of system and user time; its
22499stack size; its @samp{nice} value; etc. These commands are supported
22500on @sc{gnu}/Linux and FreeBSD.
22501
22502For @sc{gnu}/Linux systems, see the @samp{proc} man page for more
22503information (type @kbd{man 5 proc} from your shell prompt).
22504
22505For FreeBSD systems, @code{info proc stat} is an alias for @code{info
22506proc status}.
60bf7e09
EZ
22507
22508@item info proc all
22509Show all the information about the process described under all of the
22510above @code{info proc} subcommands.
22511
8e04817f
AC
22512@ignore
22513@comment These sub-options of 'info proc' were not included when
22514@comment procfs.c was re-written. Keep their descriptions around
22515@comment against the day when someone finds the time to put them back in.
22516@kindex info proc times
22517@item info proc times
22518Starting time, user CPU time, and system CPU time for your program and
22519its children.
6cf7e474 22520
8e04817f
AC
22521@kindex info proc id
22522@item info proc id
22523Report on the process IDs related to your program: its own process ID,
22524the ID of its parent, the process group ID, and the session ID.
8e04817f 22525@end ignore
721c2651
EZ
22526
22527@item set procfs-trace
22528@kindex set procfs-trace
22529@cindex @code{procfs} API calls
22530This command enables and disables tracing of @code{procfs} API calls.
22531
22532@item show procfs-trace
22533@kindex show procfs-trace
22534Show the current state of @code{procfs} API call tracing.
22535
22536@item set procfs-file @var{file}
22537@kindex set procfs-file
22538Tell @value{GDBN} to write @code{procfs} API trace to the named
22539@var{file}. @value{GDBN} appends the trace info to the previous
22540contents of the file. The default is to display the trace on the
22541standard output.
22542
22543@item show procfs-file
22544@kindex show procfs-file
22545Show the file to which @code{procfs} API trace is written.
22546
22547@item proc-trace-entry
22548@itemx proc-trace-exit
22549@itemx proc-untrace-entry
22550@itemx proc-untrace-exit
22551@kindex proc-trace-entry
22552@kindex proc-trace-exit
22553@kindex proc-untrace-entry
22554@kindex proc-untrace-exit
22555These commands enable and disable tracing of entries into and exits
22556from the @code{syscall} interface.
22557
22558@item info pidlist
22559@kindex info pidlist
22560@cindex process list, QNX Neutrino
22561For QNX Neutrino only, this command displays the list of all the
22562processes and all the threads within each process.
22563
22564@item info meminfo
22565@kindex info meminfo
22566@cindex mapinfo list, QNX Neutrino
22567For QNX Neutrino only, this command displays the list of all mapinfos.
8e04817f 22568@end table
104c1213 22569
8e04817f
AC
22570@node DJGPP Native
22571@subsection Features for Debugging @sc{djgpp} Programs
22572@cindex @sc{djgpp} debugging
22573@cindex native @sc{djgpp} debugging
22574@cindex MS-DOS-specific commands
104c1213 22575
514c4d71
EZ
22576@cindex DPMI
22577@sc{djgpp} is a port of the @sc{gnu} development tools to MS-DOS and
8e04817f
AC
22578MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs
22579that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on
22580top of real-mode DOS systems and their emulations.
104c1213 22581
8e04817f
AC
22582@value{GDBN} supports native debugging of @sc{djgpp} programs, and
22583defines a few commands specific to the @sc{djgpp} port. This
22584subsection describes those commands.
104c1213 22585
8e04817f
AC
22586@table @code
22587@kindex info dos
22588@item info dos
22589This is a prefix of @sc{djgpp}-specific commands which print
22590information about the target system and important OS structures.
f1251bdd 22591
8e04817f
AC
22592@kindex sysinfo
22593@cindex MS-DOS system info
22594@cindex free memory information (MS-DOS)
22595@item info dos sysinfo
22596This command displays assorted information about the underlying
22597platform: the CPU type and features, the OS version and flavor, the
22598DPMI version, and the available conventional and DPMI memory.
104c1213 22599
8e04817f
AC
22600@cindex GDT
22601@cindex LDT
22602@cindex IDT
22603@cindex segment descriptor tables
22604@cindex descriptor tables display
22605@item info dos gdt
22606@itemx info dos ldt
22607@itemx info dos idt
22608These 3 commands display entries from, respectively, Global, Local,
22609and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor
22610tables are data structures which store a descriptor for each segment
22611that is currently in use. The segment's selector is an index into a
22612descriptor table; the table entry for that index holds the
22613descriptor's base address and limit, and its attributes and access
22614rights.
104c1213 22615
8e04817f
AC
22616A typical @sc{djgpp} program uses 3 segments: a code segment, a data
22617segment (used for both data and the stack), and a DOS segment (which
22618allows access to DOS/BIOS data structures and absolute addresses in
22619conventional memory). However, the DPMI host will usually define
22620additional segments in order to support the DPMI environment.
d4f3574e 22621
8e04817f
AC
22622@cindex garbled pointers
22623These commands allow to display entries from the descriptor tables.
22624Without an argument, all entries from the specified table are
22625displayed. An argument, which should be an integer expression, means
22626display a single entry whose index is given by the argument. For
22627example, here's a convenient way to display information about the
22628debugged program's data segment:
104c1213 22629
8e04817f
AC
22630@smallexample
22631@exdent @code{(@value{GDBP}) info dos ldt $ds}
22632@exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)}
22633@end smallexample
104c1213 22634
8e04817f
AC
22635@noindent
22636This comes in handy when you want to see whether a pointer is outside
22637the data segment's limit (i.e.@: @dfn{garbled}).
104c1213 22638
8e04817f
AC
22639@cindex page tables display (MS-DOS)
22640@item info dos pde
22641@itemx info dos pte
22642These two commands display entries from, respectively, the Page
22643Directory and the Page Tables. Page Directories and Page Tables are
22644data structures which control how virtual memory addresses are mapped
22645into physical addresses. A Page Table includes an entry for every
22646page of memory that is mapped into the program's address space; there
22647may be several Page Tables, each one holding up to 4096 entries. A
22648Page Directory has up to 4096 entries, one each for every Page Table
22649that is currently in use.
104c1213 22650
8e04817f
AC
22651Without an argument, @kbd{info dos pde} displays the entire Page
22652Directory, and @kbd{info dos pte} displays all the entries in all of
22653the Page Tables. An argument, an integer expression, given to the
22654@kbd{info dos pde} command means display only that entry from the Page
22655Directory table. An argument given to the @kbd{info dos pte} command
22656means display entries from a single Page Table, the one pointed to by
22657the specified entry in the Page Directory.
104c1213 22658
8e04817f
AC
22659@cindex direct memory access (DMA) on MS-DOS
22660These commands are useful when your program uses @dfn{DMA} (Direct
22661Memory Access), which needs physical addresses to program the DMA
22662controller.
104c1213 22663
8e04817f 22664These commands are supported only with some DPMI servers.
104c1213 22665
8e04817f
AC
22666@cindex physical address from linear address
22667@item info dos address-pte @var{addr}
22668This command displays the Page Table entry for a specified linear
514c4d71
EZ
22669address. The argument @var{addr} is a linear address which should
22670already have the appropriate segment's base address added to it,
22671because this command accepts addresses which may belong to @emph{any}
22672segment. For example, here's how to display the Page Table entry for
22673the page where a variable @code{i} is stored:
104c1213 22674
b383017d 22675@smallexample
8e04817f
AC
22676@exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i}
22677@exdent @code{Page Table entry for address 0x11a00d30:}
b383017d 22678@exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30}
8e04817f 22679@end smallexample
104c1213 22680
8e04817f
AC
22681@noindent
22682This says that @code{i} is stored at offset @code{0xd30} from the page
514c4d71 22683whose physical base address is @code{0x02698000}, and shows all the
8e04817f 22684attributes of that page.
104c1213 22685
8e04817f
AC
22686Note that you must cast the addresses of variables to a @code{char *},
22687since otherwise the value of @code{__djgpp_base_address}, the base
22688address of all variables and functions in a @sc{djgpp} program, will
22689be added using the rules of C pointer arithmetics: if @code{i} is
22690declared an @code{int}, @value{GDBN} will add 4 times the value of
22691@code{__djgpp_base_address} to the address of @code{i}.
104c1213 22692
8e04817f
AC
22693Here's another example, it displays the Page Table entry for the
22694transfer buffer:
104c1213 22695
8e04817f
AC
22696@smallexample
22697@exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)}
22698@exdent @code{Page Table entry for address 0x29110:}
22699@exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110}
22700@end smallexample
104c1213 22701
8e04817f
AC
22702@noindent
22703(The @code{+ 3} offset is because the transfer buffer's address is the
514c4d71
EZ
227043rd member of the @code{_go32_info_block} structure.) The output
22705clearly shows that this DPMI server maps the addresses in conventional
22706memory 1:1, i.e.@: the physical (@code{0x00029000} + @code{0x110}) and
22707linear (@code{0x29110}) addresses are identical.
104c1213 22708
8e04817f
AC
22709This command is supported only with some DPMI servers.
22710@end table
104c1213 22711
c45da7e6 22712@cindex DOS serial data link, remote debugging
a8f24a35
EZ
22713In addition to native debugging, the DJGPP port supports remote
22714debugging via a serial data link. The following commands are specific
22715to remote serial debugging in the DJGPP port of @value{GDBN}.
22716
22717@table @code
22718@kindex set com1base
22719@kindex set com1irq
22720@kindex set com2base
22721@kindex set com2irq
22722@kindex set com3base
22723@kindex set com3irq
22724@kindex set com4base
22725@kindex set com4irq
22726@item set com1base @var{addr}
22727This command sets the base I/O port address of the @file{COM1} serial
22728port.
22729
22730@item set com1irq @var{irq}
22731This command sets the @dfn{Interrupt Request} (@code{IRQ}) line to use
22732for the @file{COM1} serial port.
22733
22734There are similar commands @samp{set com2base}, @samp{set com3irq},
22735etc.@: for setting the port address and the @code{IRQ} lines for the
22736other 3 COM ports.
22737
22738@kindex show com1base
22739@kindex show com1irq
22740@kindex show com2base
22741@kindex show com2irq
22742@kindex show com3base
22743@kindex show com3irq
22744@kindex show com4base
22745@kindex show com4irq
22746The related commands @samp{show com1base}, @samp{show com1irq} etc.@:
22747display the current settings of the base address and the @code{IRQ}
22748lines used by the COM ports.
c45da7e6
EZ
22749
22750@item info serial
22751@kindex info serial
22752@cindex DOS serial port status
22753This command prints the status of the 4 DOS serial ports. For each
22754port, it prints whether it's active or not, its I/O base address and
22755IRQ number, whether it uses a 16550-style FIFO, its baudrate, and the
22756counts of various errors encountered so far.
a8f24a35
EZ
22757@end table
22758
22759
78c47bea 22760@node Cygwin Native
79a6e687 22761@subsection Features for Debugging MS Windows PE Executables
78c47bea
PM
22762@cindex MS Windows debugging
22763@cindex native Cygwin debugging
22764@cindex Cygwin-specific commands
22765
be448670 22766@value{GDBN} supports native debugging of MS Windows programs, including
cbb8f428
EZ
22767DLLs with and without symbolic debugging information.
22768
22769@cindex Ctrl-BREAK, MS-Windows
22770@cindex interrupt debuggee on MS-Windows
22771MS-Windows programs that call @code{SetConsoleMode} to switch off the
22772special meaning of the @samp{Ctrl-C} keystroke cannot be interrupted
22773by typing @kbd{C-c}. For this reason, @value{GDBN} on MS-Windows
22774supports @kbd{C-@key{BREAK}} as an alternative interrupt key
22775sequence, which can be used to interrupt the debuggee even if it
22776ignores @kbd{C-c}.
22777
22778There are various additional Cygwin-specific commands, described in
22779this section. Working with DLLs that have no debugging symbols is
22780described in @ref{Non-debug DLL Symbols}.
78c47bea
PM
22781
22782@table @code
22783@kindex info w32
22784@item info w32
db2e3e2e 22785This is a prefix of MS Windows-specific commands which print
78c47bea
PM
22786information about the target system and important OS structures.
22787
22788@item info w32 selector
22789This command displays information returned by
22790the Win32 API @code{GetThreadSelectorEntry} function.
22791It takes an optional argument that is evaluated to
22792a long value to give the information about this given selector.
22793Without argument, this command displays information
d3e8051b 22794about the six segment registers.
78c47bea 22795
711e434b
PM
22796@item info w32 thread-information-block
22797This command displays thread specific information stored in the
22798Thread Information Block (readable on the X86 CPU family using @code{$fs}
22799selector for 32-bit programs and @code{$gs} for 64-bit programs).
22800
463888ab
РИ
22801@kindex signal-event
22802@item signal-event @var{id}
22803This command signals an event with user-provided @var{id}. Used to resume
22804crashing process when attached to it using MS-Windows JIT debugging (AeDebug).
22805
22806To use it, create or edit the following keys in
22807@code{HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug} and/or
22808@code{HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\AeDebug}
22809(for x86_64 versions):
22810
22811@itemize @minus
22812@item
22813@code{Debugger} (REG_SZ) --- a command to launch the debugger.
22814Suggested command is: @code{@var{fully-qualified-path-to-gdb.exe} -ex
22815"attach %ld" -ex "signal-event %ld" -ex "continue"}.
22816
22817The first @code{%ld} will be replaced by the process ID of the
22818crashing process, the second @code{%ld} will be replaced by the ID of
22819the event that blocks the crashing process, waiting for @value{GDBN}
22820to attach.
22821
22822@item
22823@code{Auto} (REG_SZ) --- either @code{1} or @code{0}. @code{1} will
22824make the system run debugger specified by the Debugger key
22825automatically, @code{0} will cause a dialog box with ``OK'' and
22826``Cancel'' buttons to appear, which allows the user to either
22827terminate the crashing process (OK) or debug it (Cancel).
22828@end itemize
22829
be90c084 22830@kindex set cygwin-exceptions
e16b02ee
EZ
22831@cindex debugging the Cygwin DLL
22832@cindex Cygwin DLL, debugging
be90c084 22833@item set cygwin-exceptions @var{mode}
e16b02ee
EZ
22834If @var{mode} is @code{on}, @value{GDBN} will break on exceptions that
22835happen inside the Cygwin DLL. If @var{mode} is @code{off},
22836@value{GDBN} will delay recognition of exceptions, and may ignore some
22837exceptions which seem to be caused by internal Cygwin DLL
22838``bookkeeping''. This option is meant primarily for debugging the
22839Cygwin DLL itself; the default value is @code{off} to avoid annoying
22840@value{GDBN} users with false @code{SIGSEGV} signals.
be90c084
CF
22841
22842@kindex show cygwin-exceptions
22843@item show cygwin-exceptions
e16b02ee
EZ
22844Displays whether @value{GDBN} will break on exceptions that happen
22845inside the Cygwin DLL itself.
be90c084 22846
b383017d 22847@kindex set new-console
78c47bea 22848@item set new-console @var{mode}
b383017d 22849If @var{mode} is @code{on} the debuggee will
78c47bea 22850be started in a new console on next start.
e03e5e7b 22851If @var{mode} is @code{off}, the debuggee will
78c47bea
PM
22852be started in the same console as the debugger.
22853
22854@kindex show new-console
22855@item show new-console
22856Displays whether a new console is used
22857when the debuggee is started.
22858
22859@kindex set new-group
22860@item set new-group @var{mode}
22861This boolean value controls whether the debuggee should
22862start a new group or stay in the same group as the debugger.
22863This affects the way the Windows OS handles
c8aa23ab 22864@samp{Ctrl-C}.
78c47bea
PM
22865
22866@kindex show new-group
22867@item show new-group
22868Displays current value of new-group boolean.
22869
22870@kindex set debugevents
22871@item set debugevents
219eec71
EZ
22872This boolean value adds debug output concerning kernel events related
22873to the debuggee seen by the debugger. This includes events that
22874signal thread and process creation and exit, DLL loading and
22875unloading, console interrupts, and debugging messages produced by the
22876Windows @code{OutputDebugString} API call.
78c47bea
PM
22877
22878@kindex set debugexec
22879@item set debugexec
b383017d 22880This boolean value adds debug output concerning execute events
219eec71 22881(such as resume thread) seen by the debugger.
78c47bea
PM
22882
22883@kindex set debugexceptions
22884@item set debugexceptions
219eec71
EZ
22885This boolean value adds debug output concerning exceptions in the
22886debuggee seen by the debugger.
78c47bea
PM
22887
22888@kindex set debugmemory
22889@item set debugmemory
219eec71
EZ
22890This boolean value adds debug output concerning debuggee memory reads
22891and writes by the debugger.
78c47bea
PM
22892
22893@kindex set shell
22894@item set shell
22895This boolean values specifies whether the debuggee is called
22896via a shell or directly (default value is on).
22897
22898@kindex show shell
22899@item show shell
22900Displays if the debuggee will be started with a shell.
22901
22902@end table
22903
be448670 22904@menu
79a6e687 22905* Non-debug DLL Symbols:: Support for DLLs without debugging symbols
be448670
CF
22906@end menu
22907
79a6e687
BW
22908@node Non-debug DLL Symbols
22909@subsubsection Support for DLLs without Debugging Symbols
be448670
CF
22910@cindex DLLs with no debugging symbols
22911@cindex Minimal symbols and DLLs
22912
22913Very often on windows, some of the DLLs that your program relies on do
22914not include symbolic debugging information (for example,
db2e3e2e 22915@file{kernel32.dll}). When @value{GDBN} doesn't recognize any debugging
be448670 22916symbols in a DLL, it relies on the minimal amount of symbolic
db2e3e2e 22917information contained in the DLL's export table. This section
be448670
CF
22918describes working with such symbols, known internally to @value{GDBN} as
22919``minimal symbols''.
22920
22921Note that before the debugged program has started execution, no DLLs
db2e3e2e 22922will have been loaded. The easiest way around this problem is simply to
be448670 22923start the program --- either by setting a breakpoint or letting the
95060284 22924program run once to completion.
be448670 22925
79a6e687 22926@subsubsection DLL Name Prefixes
be448670
CF
22927
22928In keeping with the naming conventions used by the Microsoft debugging
22929tools, DLL export symbols are made available with a prefix based on the
22930DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is
22931also entered into the symbol table, so @code{CreateFileA} is often
99e008fe 22932sufficient. In some cases there will be name clashes within a program
be448670
CF
22933(particularly if the executable itself includes full debugging symbols)
22934necessitating the use of the fully qualified name when referring to the
99e008fe 22935contents of the DLL. Use single-quotes around the name to avoid the
be448670
CF
22936exclamation mark (``!'') being interpreted as a language operator.
22937
22938Note that the internal name of the DLL may be all upper-case, even
99e008fe 22939though the file name of the DLL is lower-case, or vice-versa. Since
be448670
CF
22940symbols within @value{GDBN} are @emph{case-sensitive} this may cause
22941some confusion. If in doubt, try the @code{info functions} and
0869d01b
NR
22942@code{info variables} commands or even @code{maint print msymbols}
22943(@pxref{Symbols}). Here's an example:
be448670
CF
22944
22945@smallexample
f7dc1244 22946(@value{GDBP}) info function CreateFileA
be448670
CF
22947All functions matching regular expression "CreateFileA":
22948
22949Non-debugging symbols:
229500x77e885f4 CreateFileA
229510x77e885f4 KERNEL32!CreateFileA
22952@end smallexample
22953
22954@smallexample
f7dc1244 22955(@value{GDBP}) info function !
be448670
CF
22956All functions matching regular expression "!":
22957
22958Non-debugging symbols:
229590x6100114c cygwin1!__assert
229600x61004034 cygwin1!_dll_crt0@@0
229610x61004240 cygwin1!dll_crt0(per_process *)
22962[etc...]
22963@end smallexample
22964
79a6e687 22965@subsubsection Working with Minimal Symbols
be448670
CF
22966
22967Symbols extracted from a DLL's export table do not contain very much
22968type information. All that @value{GDBN} can do is guess whether a symbol
22969refers to a function or variable depending on the linker section that
22970contains the symbol. Also note that the actual contents of the memory
22971contained in a DLL are not available unless the program is running. This
22972means that you cannot examine the contents of a variable or disassemble
22973a function within a DLL without a running program.
22974
22975Variables are generally treated as pointers and dereferenced
22976automatically. For this reason, it is often necessary to prefix a
22977variable name with the address-of operator (``&'') and provide explicit
22978type information in the command. Here's an example of the type of
22979problem:
22980
22981@smallexample
f7dc1244 22982(@value{GDBP}) print 'cygwin1!__argv'
d69cf9b2 22983'cygwin1!__argv' has unknown type; cast it to its declared type
be448670
CF
22984@end smallexample
22985
22986@smallexample
f7dc1244 22987(@value{GDBP}) x 'cygwin1!__argv'
d69cf9b2 22988'cygwin1!__argv' has unknown type; cast it to its declared type
be448670
CF
22989@end smallexample
22990
22991And two possible solutions:
22992
22993@smallexample
f7dc1244 22994(@value{GDBP}) print ((char **)'cygwin1!__argv')[0]
be448670
CF
22995$2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram"
22996@end smallexample
22997
22998@smallexample
f7dc1244 22999(@value{GDBP}) x/2x &'cygwin1!__argv'
be448670 230000x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000
f7dc1244 23001(@value{GDBP}) x/x 0x10021608
be448670 230020x10021608: 0x0022fd98
f7dc1244 23003(@value{GDBP}) x/s 0x0022fd98
be448670
CF
230040x22fd98: "/cygdrive/c/mydirectory/myprogram"
23005@end smallexample
23006
23007Setting a break point within a DLL is possible even before the program
23008starts execution. However, under these circumstances, @value{GDBN} can't
23009examine the initial instructions of the function in order to skip the
23010function's frame set-up code. You can work around this by using ``*&''
23011to set the breakpoint at a raw memory address:
23012
23013@smallexample
f7dc1244 23014(@value{GDBP}) break *&'python22!PyOS_Readline'
be448670
CF
23015Breakpoint 1 at 0x1e04eff0
23016@end smallexample
23017
23018The author of these extensions is not entirely convinced that setting a
23019break point within a shared DLL like @file{kernel32.dll} is completely
23020safe.
23021
14d6dd68 23022@node Hurd Native
79a6e687 23023@subsection Commands Specific to @sc{gnu} Hurd Systems
14d6dd68
EZ
23024@cindex @sc{gnu} Hurd debugging
23025
23026This subsection describes @value{GDBN} commands specific to the
23027@sc{gnu} Hurd native debugging.
23028
23029@table @code
23030@item set signals
23031@itemx set sigs
23032@kindex set signals@r{, Hurd command}
23033@kindex set sigs@r{, Hurd command}
23034This command toggles the state of inferior signal interception by
23035@value{GDBN}. Mach exceptions, such as breakpoint traps, are not
23036affected by this command. @code{sigs} is a shorthand alias for
23037@code{signals}.
23038
23039@item show signals
23040@itemx show sigs
23041@kindex show signals@r{, Hurd command}
23042@kindex show sigs@r{, Hurd command}
23043Show the current state of intercepting inferior's signals.
23044
23045@item set signal-thread
23046@itemx set sigthread
23047@kindex set signal-thread
23048@kindex set sigthread
23049This command tells @value{GDBN} which thread is the @code{libc} signal
23050thread. That thread is run when a signal is delivered to a running
23051process. @code{set sigthread} is the shorthand alias of @code{set
23052signal-thread}.
23053
23054@item show signal-thread
23055@itemx show sigthread
23056@kindex show signal-thread
23057@kindex show sigthread
23058These two commands show which thread will run when the inferior is
23059delivered a signal.
23060
23061@item set stopped
23062@kindex set stopped@r{, Hurd command}
23063This commands tells @value{GDBN} that the inferior process is stopped,
23064as with the @code{SIGSTOP} signal. The stopped process can be
23065continued by delivering a signal to it.
23066
23067@item show stopped
23068@kindex show stopped@r{, Hurd command}
23069This command shows whether @value{GDBN} thinks the debuggee is
23070stopped.
23071
23072@item set exceptions
23073@kindex set exceptions@r{, Hurd command}
23074Use this command to turn off trapping of exceptions in the inferior.
23075When exception trapping is off, neither breakpoints nor
23076single-stepping will work. To restore the default, set exception
23077trapping on.
23078
23079@item show exceptions
23080@kindex show exceptions@r{, Hurd command}
23081Show the current state of trapping exceptions in the inferior.
23082
23083@item set task pause
23084@kindex set task@r{, Hurd commands}
23085@cindex task attributes (@sc{gnu} Hurd)
23086@cindex pause current task (@sc{gnu} Hurd)
23087This command toggles task suspension when @value{GDBN} has control.
23088Setting it to on takes effect immediately, and the task is suspended
23089whenever @value{GDBN} gets control. Setting it to off will take
23090effect the next time the inferior is continued. If this option is set
23091to off, you can use @code{set thread default pause on} or @code{set
23092thread pause on} (see below) to pause individual threads.
23093
23094@item show task pause
23095@kindex show task@r{, Hurd commands}
23096Show the current state of task suspension.
23097
23098@item set task detach-suspend-count
23099@cindex task suspend count
23100@cindex detach from task, @sc{gnu} Hurd
23101This command sets the suspend count the task will be left with when
23102@value{GDBN} detaches from it.
23103
23104@item show task detach-suspend-count
23105Show the suspend count the task will be left with when detaching.
23106
23107@item set task exception-port
23108@itemx set task excp
23109@cindex task exception port, @sc{gnu} Hurd
23110This command sets the task exception port to which @value{GDBN} will
23111forward exceptions. The argument should be the value of the @dfn{send
23112rights} of the task. @code{set task excp} is a shorthand alias.
23113
23114@item set noninvasive
23115@cindex noninvasive task options
23116This command switches @value{GDBN} to a mode that is the least
23117invasive as far as interfering with the inferior is concerned. This
23118is the same as using @code{set task pause}, @code{set exceptions}, and
23119@code{set signals} to values opposite to the defaults.
23120
23121@item info send-rights
23122@itemx info receive-rights
23123@itemx info port-rights
23124@itemx info port-sets
23125@itemx info dead-names
23126@itemx info ports
23127@itemx info psets
23128@cindex send rights, @sc{gnu} Hurd
23129@cindex receive rights, @sc{gnu} Hurd
23130@cindex port rights, @sc{gnu} Hurd
23131@cindex port sets, @sc{gnu} Hurd
23132@cindex dead names, @sc{gnu} Hurd
23133These commands display information about, respectively, send rights,
23134receive rights, port rights, port sets, and dead names of a task.
23135There are also shorthand aliases: @code{info ports} for @code{info
23136port-rights} and @code{info psets} for @code{info port-sets}.
23137
23138@item set thread pause
23139@kindex set thread@r{, Hurd command}
23140@cindex thread properties, @sc{gnu} Hurd
23141@cindex pause current thread (@sc{gnu} Hurd)
23142This command toggles current thread suspension when @value{GDBN} has
23143control. Setting it to on takes effect immediately, and the current
23144thread is suspended whenever @value{GDBN} gets control. Setting it to
23145off will take effect the next time the inferior is continued.
23146Normally, this command has no effect, since when @value{GDBN} has
23147control, the whole task is suspended. However, if you used @code{set
23148task pause off} (see above), this command comes in handy to suspend
23149only the current thread.
23150
23151@item show thread pause
23152@kindex show thread@r{, Hurd command}
23153This command shows the state of current thread suspension.
23154
23155@item set thread run
d3e8051b 23156This command sets whether the current thread is allowed to run.
14d6dd68
EZ
23157
23158@item show thread run
23159Show whether the current thread is allowed to run.
23160
23161@item set thread detach-suspend-count
23162@cindex thread suspend count, @sc{gnu} Hurd
23163@cindex detach from thread, @sc{gnu} Hurd
23164This command sets the suspend count @value{GDBN} will leave on a
23165thread when detaching. This number is relative to the suspend count
23166found by @value{GDBN} when it notices the thread; use @code{set thread
23167takeover-suspend-count} to force it to an absolute value.
23168
23169@item show thread detach-suspend-count
23170Show the suspend count @value{GDBN} will leave on the thread when
23171detaching.
23172
23173@item set thread exception-port
23174@itemx set thread excp
23175Set the thread exception port to which to forward exceptions. This
23176overrides the port set by @code{set task exception-port} (see above).
23177@code{set thread excp} is the shorthand alias.
23178
23179@item set thread takeover-suspend-count
23180Normally, @value{GDBN}'s thread suspend counts are relative to the
23181value @value{GDBN} finds when it notices each thread. This command
23182changes the suspend counts to be absolute instead.
23183
23184@item set thread default
23185@itemx show thread default
23186@cindex thread default settings, @sc{gnu} Hurd
23187Each of the above @code{set thread} commands has a @code{set thread
23188default} counterpart (e.g., @code{set thread default pause}, @code{set
23189thread default exception-port}, etc.). The @code{thread default}
23190variety of commands sets the default thread properties for all
23191threads; you can then change the properties of individual threads with
23192the non-default commands.
23193@end table
23194
a80b95ba
TG
23195@node Darwin
23196@subsection Darwin
23197@cindex Darwin
23198
23199@value{GDBN} provides the following commands specific to the Darwin target:
23200
23201@table @code
23202@item set debug darwin @var{num}
23203@kindex set debug darwin
23204When set to a non zero value, enables debugging messages specific to
23205the Darwin support. Higher values produce more verbose output.
23206
23207@item show debug darwin
23208@kindex show debug darwin
23209Show the current state of Darwin messages.
23210
23211@item set debug mach-o @var{num}
23212@kindex set debug mach-o
23213When set to a non zero value, enables debugging messages while
23214@value{GDBN} is reading Darwin object files. (@dfn{Mach-O} is the
23215file format used on Darwin for object and executable files.) Higher
23216values produce more verbose output. This is a command to diagnose
23217problems internal to @value{GDBN} and should not be needed in normal
23218usage.
23219
23220@item show debug mach-o
23221@kindex show debug mach-o
23222Show the current state of Mach-O file messages.
23223
23224@item set mach-exceptions on
23225@itemx set mach-exceptions off
23226@kindex set mach-exceptions
23227On Darwin, faults are first reported as a Mach exception and are then
23228mapped to a Posix signal. Use this command to turn on trapping of
23229Mach exceptions in the inferior. This might be sometimes useful to
23230better understand the cause of a fault. The default is off.
23231
23232@item show mach-exceptions
23233@kindex show mach-exceptions
23234Show the current state of exceptions trapping.
23235@end table
23236
e9076973
JB
23237@node FreeBSD
23238@subsection FreeBSD
23239@cindex FreeBSD
23240
23241When the ABI of a system call is changed in the FreeBSD kernel, this
23242is implemented by leaving a compatibility system call using the old
23243ABI at the existing number and allocating a new system call number for
23244the version using the new ABI. As a convenience, when a system call
23245is caught by name (@pxref{catch syscall}), compatibility system calls
23246are also caught.
23247
23248For example, FreeBSD 12 introduced a new variant of the @code{kevent}
23249system call and catching the @code{kevent} system call by name catches
23250both variants:
23251
23252@smallexample
23253(@value{GDBP}) catch syscall kevent
23254Catchpoint 1 (syscalls 'freebsd11_kevent' [363] 'kevent' [560])
23255(@value{GDBP})
23256@end smallexample
23257
a64548ea 23258
8e04817f
AC
23259@node Embedded OS
23260@section Embedded Operating Systems
104c1213 23261
8e04817f
AC
23262This section describes configurations involving the debugging of
23263embedded operating systems that are available for several different
23264architectures.
d4f3574e 23265
8e04817f
AC
23266@value{GDBN} includes the ability to debug programs running on
23267various real-time operating systems.
104c1213 23268
6d2ebf8b 23269@node Embedded Processors
104c1213
JM
23270@section Embedded Processors
23271
23272This section goes into details specific to particular embedded
23273configurations.
23274
c45da7e6
EZ
23275@cindex send command to simulator
23276Whenever a specific embedded processor has a simulator, @value{GDBN}
23277allows to send an arbitrary command to the simulator.
23278
23279@table @code
23280@item sim @var{command}
23281@kindex sim@r{, a command}
23282Send an arbitrary @var{command} string to the simulator. Consult the
23283documentation for the specific simulator in use for information about
23284acceptable commands.
23285@end table
23286
7d86b5d5 23287
104c1213 23288@menu
ad0a504f 23289* ARC:: Synopsys ARC
bb615428 23290* ARM:: ARM
104c1213 23291* M68K:: Motorola M68K
08be9d71 23292* MicroBlaze:: Xilinx MicroBlaze
104c1213 23293* MIPS Embedded:: MIPS Embedded
a994fec4 23294* OpenRISC 1000:: OpenRISC 1000 (or1k)
4acd40f3 23295* PowerPC Embedded:: PowerPC Embedded
a64548ea
EZ
23296* AVR:: Atmel AVR
23297* CRIS:: CRIS
23298* Super-H:: Renesas Super-H
104c1213
JM
23299@end menu
23300
ad0a504f
AK
23301@node ARC
23302@subsection Synopsys ARC
23303@cindex Synopsys ARC
23304@cindex ARC specific commands
23305@cindex ARC600
23306@cindex ARC700
23307@cindex ARC EM
23308@cindex ARC HS
23309
23310@value{GDBN} provides the following ARC-specific commands:
23311
23312@table @code
23313@item set debug arc
23314@kindex set debug arc
23315Control the level of ARC specific debug messages. Use 0 for no messages (the
fe5f7374 23316default), 1 for debug messages, and 2 for even more debug messages.
ad0a504f
AK
23317
23318@item show debug arc
23319@kindex show debug arc
23320Show the level of ARC specific debugging in operation.
23321
eea78757
AK
23322@item maint print arc arc-instruction @var{address}
23323@kindex maint print arc arc-instruction
23324Print internal disassembler information about instruction at a given address.
23325
ad0a504f
AK
23326@end table
23327
6d2ebf8b 23328@node ARM
104c1213 23329@subsection ARM
8e04817f 23330
e2f4edfd
EZ
23331@value{GDBN} provides the following ARM-specific commands:
23332
23333@table @code
23334@item set arm disassembler
23335@kindex set arm
23336This commands selects from a list of disassembly styles. The
23337@code{"std"} style is the standard style.
23338
23339@item show arm disassembler
23340@kindex show arm
23341Show the current disassembly style.
23342
23343@item set arm apcs32
23344@cindex ARM 32-bit mode
23345This command toggles ARM operation mode between 32-bit and 26-bit.
23346
23347@item show arm apcs32
23348Display the current usage of the ARM 32-bit mode.
23349
23350@item set arm fpu @var{fputype}
23351This command sets the ARM floating-point unit (FPU) type. The
23352argument @var{fputype} can be one of these:
23353
23354@table @code
23355@item auto
23356Determine the FPU type by querying the OS ABI.
23357@item softfpa
23358Software FPU, with mixed-endian doubles on little-endian ARM
23359processors.
23360@item fpa
23361GCC-compiled FPA co-processor.
23362@item softvfp
23363Software FPU with pure-endian doubles.
23364@item vfp
23365VFP co-processor.
23366@end table
23367
23368@item show arm fpu
23369Show the current type of the FPU.
23370
23371@item set arm abi
23372This command forces @value{GDBN} to use the specified ABI.
23373
23374@item show arm abi
23375Show the currently used ABI.
23376
0428b8f5
DJ
23377@item set arm fallback-mode (arm|thumb|auto)
23378@value{GDBN} uses the symbol table, when available, to determine
23379whether instructions are ARM or Thumb. This command controls
23380@value{GDBN}'s default behavior when the symbol table is not
23381available. The default is @samp{auto}, which causes @value{GDBN} to
23382use the current execution mode (from the @code{T} bit in the @code{CPSR}
23383register).
23384
23385@item show arm fallback-mode
23386Show the current fallback instruction mode.
23387
23388@item set arm force-mode (arm|thumb|auto)
23389This command overrides use of the symbol table to determine whether
23390instructions are ARM or Thumb. The default is @samp{auto}, which
23391causes @value{GDBN} to use the symbol table and then the setting
23392of @samp{set arm fallback-mode}.
23393
23394@item show arm force-mode
23395Show the current forced instruction mode.
23396
e2f4edfd
EZ
23397@item set debug arm
23398Toggle whether to display ARM-specific debugging messages from the ARM
23399target support subsystem.
23400
23401@item show debug arm
23402Show whether ARM-specific debugging messages are enabled.
23403@end table
23404
ee8e71d4
EZ
23405@table @code
23406@item target sim @r{[}@var{simargs}@r{]} @dots{}
23407The @value{GDBN} ARM simulator accepts the following optional arguments.
23408
23409@table @code
23410@item --swi-support=@var{type}
697aa1b7 23411Tell the simulator which SWI interfaces to support. The argument
ee8e71d4
EZ
23412@var{type} may be a comma separated list of the following values.
23413The default value is @code{all}.
23414
23415@table @code
23416@item none
23417@item demon
23418@item angel
23419@item redboot
23420@item all
23421@end table
23422@end table
23423@end table
e2f4edfd 23424
8e04817f
AC
23425@node M68K
23426@subsection M68k
23427
bb615428 23428The Motorola m68k configuration includes ColdFire support.
8e04817f 23429
08be9d71
ME
23430@node MicroBlaze
23431@subsection MicroBlaze
23432@cindex Xilinx MicroBlaze
23433@cindex XMD, Xilinx Microprocessor Debugger
23434
23435The MicroBlaze is a soft-core processor supported on various Xilinx
23436FPGAs, such as Spartan or Virtex series. Boards with these processors
23437usually have JTAG ports which connect to a host system running the Xilinx
23438Embedded Development Kit (EDK) or Software Development Kit (SDK).
23439This host system is used to download the configuration bitstream to
23440the target FPGA. The Xilinx Microprocessor Debugger (XMD) program
23441communicates with the target board using the JTAG interface and
23442presents a @code{gdbserver} interface to the board. By default
23443@code{xmd} uses port @code{1234}. (While it is possible to change
23444this default port, it requires the use of undocumented @code{xmd}
23445commands. Contact Xilinx support if you need to do this.)
23446
23447Use these GDB commands to connect to the MicroBlaze target processor.
23448
23449@table @code
23450@item target remote :1234
23451Use this command to connect to the target if you are running @value{GDBN}
23452on the same system as @code{xmd}.
23453
23454@item target remote @var{xmd-host}:1234
23455Use this command to connect to the target if it is connected to @code{xmd}
23456running on a different system named @var{xmd-host}.
23457
23458@item load
23459Use this command to download a program to the MicroBlaze target.
23460
23461@item set debug microblaze @var{n}
23462Enable MicroBlaze-specific debugging messages if non-zero.
23463
23464@item show debug microblaze @var{n}
23465Show MicroBlaze-specific debugging level.
23466@end table
23467
8e04817f 23468@node MIPS Embedded
eb17f351 23469@subsection @acronym{MIPS} Embedded
8e04817f 23470
8e04817f 23471@noindent
f7c38292 23472@value{GDBN} supports these special commands for @acronym{MIPS} targets:
104c1213 23473
8e04817f 23474@table @code
8e04817f
AC
23475@item set mipsfpu double
23476@itemx set mipsfpu single
23477@itemx set mipsfpu none
a64548ea 23478@itemx set mipsfpu auto
8e04817f
AC
23479@itemx show mipsfpu
23480@kindex set mipsfpu
23481@kindex show mipsfpu
eb17f351
EZ
23482@cindex @acronym{MIPS} remote floating point
23483@cindex floating point, @acronym{MIPS} remote
23484If your target board does not support the @acronym{MIPS} floating point
8e04817f
AC
23485coprocessor, you should use the command @samp{set mipsfpu none} (if you
23486need this, you may wish to put the command in your @value{GDBN} init
23487file). This tells @value{GDBN} how to find the return value of
23488functions which return floating point values. It also allows
23489@value{GDBN} to avoid saving the floating point registers when calling
23490functions on the board. If you are using a floating point coprocessor
23491with only single precision floating point support, as on the @sc{r4650}
23492processor, use the command @samp{set mipsfpu single}. The default
23493double precision floating point coprocessor may be selected using
23494@samp{set mipsfpu double}.
104c1213 23495
8e04817f
AC
23496In previous versions the only choices were double precision or no
23497floating point, so @samp{set mipsfpu on} will select double precision
23498and @samp{set mipsfpu off} will select no floating point.
104c1213 23499
8e04817f
AC
23500As usual, you can inquire about the @code{mipsfpu} variable with
23501@samp{show mipsfpu}.
8e04817f 23502@end table
104c1213 23503
a994fec4
FJ
23504@node OpenRISC 1000
23505@subsection OpenRISC 1000
23506@cindex OpenRISC 1000
23507
23508@noindent
23509The OpenRISC 1000 provides a free RISC instruction set architecture. It is
23510mainly provided as a soft-core which can run on Xilinx, Altera and other
23511FPGA's.
23512
23513@value{GDBN} for OpenRISC supports the below commands when connecting to
23514a target:
23515
23516@table @code
23517
23518@kindex target sim
23519@item target sim
23520
23521Runs the builtin CPU simulator which can run very basic
23522programs but does not support most hardware functions like MMU.
23523For more complex use cases the user is advised to run an external
23524target, and connect using @samp{target remote}.
23525
23526Example: @code{target sim}
23527
23528@item set debug or1k
23529Toggle whether to display OpenRISC-specific debugging messages from the
23530OpenRISC target support subsystem.
23531
23532@item show debug or1k
23533Show whether OpenRISC-specific debugging messages are enabled.
23534@end table
23535
4acd40f3
TJB
23536@node PowerPC Embedded
23537@subsection PowerPC Embedded
104c1213 23538
66b73624
TJB
23539@cindex DVC register
23540@value{GDBN} supports using the DVC (Data Value Compare) register to
23541implement in hardware simple hardware watchpoint conditions of the form:
23542
23543@smallexample
23544(@value{GDBP}) watch @var{ADDRESS|VARIABLE} \
23545 if @var{ADDRESS|VARIABLE} == @var{CONSTANT EXPRESSION}
23546@end smallexample
23547
e09342b5
TJB
23548The DVC register will be automatically used when @value{GDBN} detects
23549such pattern in a condition expression, and the created watchpoint uses one
23550debug register (either the @code{exact-watchpoints} option is on and the
23551variable is scalar, or the variable has a length of one byte). This feature
23552is available in native @value{GDBN} running on a Linux kernel version 2.6.34
23553or newer.
23554
23555When running on PowerPC embedded processors, @value{GDBN} automatically uses
23556ranged hardware watchpoints, unless the @code{exact-watchpoints} option is on,
23557in which case watchpoints using only one debug register are created when
23558watching variables of scalar types.
23559
23560You can create an artificial array to watch an arbitrary memory
23561region using one of the following commands (@pxref{Expressions}):
23562
23563@smallexample
23564(@value{GDBP}) watch *((char *) @var{address})@@@var{length}
23565(@value{GDBP}) watch @{char[@var{length}]@} @var{address}
23566@end smallexample
66b73624 23567
9c06b0b4
TJB
23568PowerPC embedded processors support masked watchpoints. See the discussion
23569about the @code{mask} argument in @ref{Set Watchpoints}.
23570
f1310107
TJB
23571@cindex ranged breakpoint
23572PowerPC embedded processors support hardware accelerated
23573@dfn{ranged breakpoints}. A ranged breakpoint stops execution of
23574the inferior whenever it executes an instruction at any address within
23575the range it specifies. To set a ranged breakpoint in @value{GDBN},
23576use the @code{break-range} command.
23577
55eddb0f
DJ
23578@value{GDBN} provides the following PowerPC-specific commands:
23579
104c1213 23580@table @code
f1310107
TJB
23581@kindex break-range
23582@item break-range @var{start-location}, @var{end-location}
697aa1b7
EZ
23583Set a breakpoint for an address range given by
23584@var{start-location} and @var{end-location}, which can specify a function name,
f1310107
TJB
23585a line number, an offset of lines from the current line or from the start
23586location, or an address of an instruction (see @ref{Specify Location},
23587for a list of all the possible ways to specify a @var{location}.)
23588The breakpoint will stop execution of the inferior whenever it
23589executes an instruction at any address within the specified range,
23590(including @var{start-location} and @var{end-location}.)
23591
55eddb0f
DJ
23592@kindex set powerpc
23593@item set powerpc soft-float
23594@itemx show powerpc soft-float
23595Force @value{GDBN} to use (or not use) a software floating point calling
23596convention. By default, @value{GDBN} selects the calling convention based
23597on the selected architecture and the provided executable file.
23598
23599@item set powerpc vector-abi
23600@itemx show powerpc vector-abi
23601Force @value{GDBN} to use the specified calling convention for vector
23602arguments and return values. The valid options are @samp{auto};
23603@samp{generic}, to avoid vector registers even if they are present;
23604@samp{altivec}, to use AltiVec registers; and @samp{spe} to use SPE
23605registers. By default, @value{GDBN} selects the calling convention
23606based on the selected architecture and the provided executable file.
23607
e09342b5
TJB
23608@item set powerpc exact-watchpoints
23609@itemx show powerpc exact-watchpoints
23610Allow @value{GDBN} to use only one debug register when watching a variable
23611of scalar type, thus assuming that the variable is accessed through the
23612address of its first byte.
23613
104c1213
JM
23614@end table
23615
a64548ea
EZ
23616@node AVR
23617@subsection Atmel AVR
23618@cindex AVR
23619
23620When configured for debugging the Atmel AVR, @value{GDBN} supports the
23621following AVR-specific commands:
23622
23623@table @code
23624@item info io_registers
23625@kindex info io_registers@r{, AVR}
23626@cindex I/O registers (Atmel AVR)
23627This command displays information about the AVR I/O registers. For
23628each register, @value{GDBN} prints its number and value.
23629@end table
23630
23631@node CRIS
23632@subsection CRIS
23633@cindex CRIS
23634
23635When configured for debugging CRIS, @value{GDBN} provides the
23636following CRIS-specific commands:
23637
23638@table @code
23639@item set cris-version @var{ver}
23640@cindex CRIS version
e22e55c9
OF
23641Set the current CRIS version to @var{ver}, either @samp{10} or @samp{32}.
23642The CRIS version affects register names and sizes. This command is useful in
23643case autodetection of the CRIS version fails.
a64548ea
EZ
23644
23645@item show cris-version
23646Show the current CRIS version.
23647
23648@item set cris-dwarf2-cfi
23649@cindex DWARF-2 CFI and CRIS
e22e55c9
OF
23650Set the usage of DWARF-2 CFI for CRIS debugging. The default is @samp{on}.
23651Change to @samp{off} when using @code{gcc-cris} whose version is below
23652@code{R59}.
a64548ea
EZ
23653
23654@item show cris-dwarf2-cfi
23655Show the current state of using DWARF-2 CFI.
e22e55c9
OF
23656
23657@item set cris-mode @var{mode}
23658@cindex CRIS mode
23659Set the current CRIS mode to @var{mode}. It should only be changed when
23660debugging in guru mode, in which case it should be set to
23661@samp{guru} (the default is @samp{normal}).
23662
23663@item show cris-mode
23664Show the current CRIS mode.
a64548ea
EZ
23665@end table
23666
23667@node Super-H
23668@subsection Renesas Super-H
23669@cindex Super-H
23670
23671For the Renesas Super-H processor, @value{GDBN} provides these
23672commands:
23673
23674@table @code
c055b101
CV
23675@item set sh calling-convention @var{convention}
23676@kindex set sh calling-convention
23677Set the calling-convention used when calling functions from @value{GDBN}.
23678Allowed values are @samp{gcc}, which is the default setting, and @samp{renesas}.
23679With the @samp{gcc} setting, functions are called using the @value{NGCC} calling
23680convention. If the DWARF-2 information of the called function specifies
23681that the function follows the Renesas calling convention, the function
23682is called using the Renesas calling convention. If the calling convention
23683is set to @samp{renesas}, the Renesas calling convention is always used,
23684regardless of the DWARF-2 information. This can be used to override the
23685default of @samp{gcc} if debug information is missing, or the compiler
23686does not emit the DWARF-2 calling convention entry for a function.
23687
23688@item show sh calling-convention
23689@kindex show sh calling-convention
23690Show the current calling convention setting.
23691
a64548ea
EZ
23692@end table
23693
23694
8e04817f
AC
23695@node Architectures
23696@section Architectures
104c1213 23697
8e04817f
AC
23698This section describes characteristics of architectures that affect
23699all uses of @value{GDBN} with the architecture, both native and cross.
104c1213 23700
8e04817f 23701@menu
430ed3f0 23702* AArch64::
9c16f35a 23703* i386::
8e04817f
AC
23704* Alpha::
23705* MIPS::
a64548ea 23706* HPPA:: HP PA architecture
23d964e7 23707* SPU:: Cell Broadband Engine SPU architecture
4acd40f3 23708* PowerPC::
a1217d97 23709* Nios II::
58afddc6 23710* Sparc64::
51d21d60 23711* S12Z::
8e04817f 23712@end menu
104c1213 23713
430ed3f0
MS
23714@node AArch64
23715@subsection AArch64
23716@cindex AArch64 support
23717
23718When @value{GDBN} is debugging the AArch64 architecture, it provides the
23719following special commands:
23720
23721@table @code
23722@item set debug aarch64
23723@kindex set debug aarch64
23724This command determines whether AArch64 architecture-specific debugging
23725messages are to be displayed.
23726
23727@item show debug aarch64
23728Show whether AArch64 debugging messages are displayed.
23729
23730@end table
23731
1461bdac
AH
23732@subsubsection AArch64 SVE.
23733@cindex AArch64 SVE.
23734
23735When @value{GDBN} is debugging the AArch64 architecture, if the Scalable Vector
23736Extension (SVE) is present, then @value{GDBN} will provide the vector registers
23737@code{$z0} through @code{$z31}, vector predicate registers @code{$p0} through
23738@code{$p15}, and the @code{$ffr} register. In addition, the pseudo register
23739@code{$vg} will be provided. This is the vector granule for the current thread
23740and represents the number of 64-bit chunks in an SVE @code{z} register.
23741
23742If the vector length changes, then the @code{$vg} register will be updated,
23743but the lengths of the @code{z} and @code{p} registers will not change. This
23744is a known limitation of @value{GDBN} and does not affect the execution of the
23745target process.
23746
23747
9c16f35a 23748@node i386
db2e3e2e 23749@subsection x86 Architecture-specific Issues
9c16f35a
EZ
23750
23751@table @code
23752@item set struct-convention @var{mode}
23753@kindex set struct-convention
23754@cindex struct return convention
23755@cindex struct/union returned in registers
23756Set the convention used by the inferior to return @code{struct}s and
23757@code{union}s from functions to @var{mode}. Possible values of
23758@var{mode} are @code{"pcc"}, @code{"reg"}, and @code{"default"} (the
23759default). @code{"default"} or @code{"pcc"} means that @code{struct}s
23760are returned on the stack, while @code{"reg"} means that a
23761@code{struct} or a @code{union} whose size is 1, 2, 4, or 8 bytes will
23762be returned in a register.
23763
23764@item show struct-convention
23765@kindex show struct-convention
23766Show the current setting of the convention to return @code{struct}s
23767from functions.
966f0aef 23768@end table
29c1c244 23769
ca8941bb 23770
bc504a31
PA
23771@subsubsection Intel @dfn{Memory Protection Extensions} (MPX).
23772@cindex Intel Memory Protection Extensions (MPX).
ca8941bb 23773
ca8941bb
WT
23774Memory Protection Extension (MPX) adds the bound registers @samp{BND0}
23775@footnote{The register named with capital letters represent the architecture
23776registers.} through @samp{BND3}. Bound registers store a pair of 64-bit values
23777which are the lower bound and upper bound. Bounds are effective addresses or
23778memory locations. The upper bounds are architecturally represented in 1's
23779complement form. A bound having lower bound = 0, and upper bound = 0
23780(1's complement of all bits set) will allow access to the entire address space.
23781
23782@samp{BND0} through @samp{BND3} are represented in @value{GDBN} as @samp{bnd0raw}
23783through @samp{bnd3raw}. Pseudo registers @samp{bnd0} through @samp{bnd3}
23784display the upper bound performing the complement of one operation on the
23785upper bound value, i.e.@ when upper bound in @samp{bnd0raw} is 0 in the
23786@value{GDBN} @samp{bnd0} it will be @code{0xfff@dots{}}. In this sense it
23787can also be noted that the upper bounds are inclusive.
23788
23789As an example, assume that the register BND0 holds bounds for a pointer having
23790access allowed for the range between 0x32 and 0x71. The values present on
23791bnd0raw and bnd registers are presented as follows:
23792
23793@smallexample
23794 bnd0raw = @{0x32, 0xffffffff8e@}
23795 bnd0 = @{lbound = 0x32, ubound = 0x71@} : size 64
23796@end smallexample
23797
22f25c9d
EZ
23798This way the raw value can be accessed via bnd0raw@dots{}bnd3raw. Any
23799change on bnd0@dots{}bnd3 or bnd0raw@dots{}bnd3raw is reflect on its
23800counterpart. When the bnd0@dots{}bnd3 registers are displayed via
23801Python, the display includes the memory size, in bits, accessible to
23802the pointer.
9c16f35a 23803
29c1c244
WT
23804Bounds can also be stored in bounds tables, which are stored in
23805application memory. These tables store bounds for pointers by specifying
23806the bounds pointer's value along with its bounds. Evaluating and changing
23807bounds located in bound tables is therefore interesting while investigating
23808bugs on MPX context. @value{GDBN} provides commands for this purpose:
23809
966f0aef 23810@table @code
29c1c244
WT
23811@item show mpx bound @var{pointer}
23812@kindex show mpx bound
23813Display bounds of the given @var{pointer}.
23814
23815@item set mpx bound @var{pointer}, @var{lbound}, @var{ubound}
23816@kindex set mpx bound
23817Set the bounds of a pointer in the bound table.
23818This command takes three parameters: @var{pointer} is the pointers
23819whose bounds are to be changed, @var{lbound} and @var{ubound} are new values
23820for lower and upper bounds respectively.
23821@end table
23822
4a612d6f
WT
23823When you call an inferior function on an Intel MPX enabled program,
23824GDB sets the inferior's bound registers to the init (disabled) state
23825before calling the function. As a consequence, bounds checks for the
23826pointer arguments passed to the function will always pass.
23827
23828This is necessary because when you call an inferior function, the
23829program is usually in the middle of the execution of other function.
23830Since at that point bound registers are in an arbitrary state, not
23831clearing them would lead to random bound violations in the called
23832function.
23833
23834You can still examine the influence of the bound registers on the
23835execution of the called function by stopping the execution of the
23836called function at its prologue, setting bound registers, and
23837continuing the execution. For example:
23838
23839@smallexample
23840 $ break *upper
23841 Breakpoint 2 at 0x4009de: file i386-mpx-call.c, line 47.
23842 $ print upper (a, b, c, d, 1)
23843 Breakpoint 2, upper (a=0x0, b=0x6e0000005b, c=0x0, d=0x0, len=48)....
23844 $ print $bnd0
5cf70512 23845 @{lbound = 0x0, ubound = ffffffff@} : size -1
4a612d6f
WT
23846@end smallexample
23847
23848At this last step the value of bnd0 can be changed for investigation of bound
23849violations caused along the execution of the call. In order to know how to
23850set the bound registers or bound table for the call consult the ABI.
23851
8e04817f
AC
23852@node Alpha
23853@subsection Alpha
104c1213 23854
8e04817f 23855See the following section.
104c1213 23856
8e04817f 23857@node MIPS
eb17f351 23858@subsection @acronym{MIPS}
104c1213 23859
8e04817f 23860@cindex stack on Alpha
eb17f351 23861@cindex stack on @acronym{MIPS}
8e04817f 23862@cindex Alpha stack
eb17f351
EZ
23863@cindex @acronym{MIPS} stack
23864Alpha- and @acronym{MIPS}-based computers use an unusual stack frame, which
8e04817f
AC
23865sometimes requires @value{GDBN} to search backward in the object code to
23866find the beginning of a function.
104c1213 23867
eb17f351 23868@cindex response time, @acronym{MIPS} debugging
8e04817f
AC
23869To improve response time (especially for embedded applications, where
23870@value{GDBN} may be restricted to a slow serial line for this search)
23871you may want to limit the size of this search, using one of these
23872commands:
104c1213 23873
8e04817f 23874@table @code
eb17f351 23875@cindex @code{heuristic-fence-post} (Alpha, @acronym{MIPS})
8e04817f
AC
23876@item set heuristic-fence-post @var{limit}
23877Restrict @value{GDBN} to examining at most @var{limit} bytes in its
23878search for the beginning of a function. A value of @var{0} (the
23879default) means there is no limit. However, except for @var{0}, the
23880larger the limit the more bytes @code{heuristic-fence-post} must search
e2f4edfd
EZ
23881and therefore the longer it takes to run. You should only need to use
23882this command when debugging a stripped executable.
104c1213 23883
8e04817f
AC
23884@item show heuristic-fence-post
23885Display the current limit.
23886@end table
104c1213
JM
23887
23888@noindent
8e04817f 23889These commands are available @emph{only} when @value{GDBN} is configured
eb17f351 23890for debugging programs on Alpha or @acronym{MIPS} processors.
104c1213 23891
eb17f351 23892Several @acronym{MIPS}-specific commands are available when debugging @acronym{MIPS}
a64548ea
EZ
23893programs:
23894
23895@table @code
a64548ea
EZ
23896@item set mips abi @var{arg}
23897@kindex set mips abi
eb17f351
EZ
23898@cindex set ABI for @acronym{MIPS}
23899Tell @value{GDBN} which @acronym{MIPS} ABI is used by the inferior. Possible
a64548ea
EZ
23900values of @var{arg} are:
23901
23902@table @samp
23903@item auto
23904The default ABI associated with the current binary (this is the
23905default).
23906@item o32
23907@item o64
23908@item n32
23909@item n64
23910@item eabi32
23911@item eabi64
a64548ea
EZ
23912@end table
23913
23914@item show mips abi
23915@kindex show mips abi
eb17f351 23916Show the @acronym{MIPS} ABI used by @value{GDBN} to debug the inferior.
a64548ea 23917
4cc0665f
MR
23918@item set mips compression @var{arg}
23919@kindex set mips compression
23920@cindex code compression, @acronym{MIPS}
23921Tell @value{GDBN} which @acronym{MIPS} compressed
23922@acronym{ISA, Instruction Set Architecture} encoding is used by the
23923inferior. @value{GDBN} uses this for code disassembly and other
23924internal interpretation purposes. This setting is only referred to
23925when no executable has been associated with the debugging session or
23926the executable does not provide information about the encoding it uses.
23927Otherwise this setting is automatically updated from information
23928provided by the executable.
23929
23930Possible values of @var{arg} are @samp{mips16} and @samp{micromips}.
23931The default compressed @acronym{ISA} encoding is @samp{mips16}, as
23932executables containing @acronym{MIPS16} code frequently are not
23933identified as such.
23934
23935This setting is ``sticky''; that is, it retains its value across
23936debugging sessions until reset either explicitly with this command or
23937implicitly from an executable.
23938
23939The compiler and/or assembler typically add symbol table annotations to
23940identify functions compiled for the @acronym{MIPS16} or
23941@acronym{microMIPS} @acronym{ISA}s. If these function-scope annotations
23942are present, @value{GDBN} uses them in preference to the global
23943compressed @acronym{ISA} encoding setting.
23944
23945@item show mips compression
23946@kindex show mips compression
23947Show the @acronym{MIPS} compressed @acronym{ISA} encoding used by
23948@value{GDBN} to debug the inferior.
23949
a64548ea
EZ
23950@item set mipsfpu
23951@itemx show mipsfpu
23952@xref{MIPS Embedded, set mipsfpu}.
23953
23954@item set mips mask-address @var{arg}
23955@kindex set mips mask-address
eb17f351 23956@cindex @acronym{MIPS} addresses, masking
a64548ea 23957This command determines whether the most-significant 32 bits of 64-bit
eb17f351 23958@acronym{MIPS} addresses are masked off. The argument @var{arg} can be
a64548ea
EZ
23959@samp{on}, @samp{off}, or @samp{auto}. The latter is the default
23960setting, which lets @value{GDBN} determine the correct value.
23961
23962@item show mips mask-address
23963@kindex show mips mask-address
eb17f351 23964Show whether the upper 32 bits of @acronym{MIPS} addresses are masked off or
a64548ea
EZ
23965not.
23966
23967@item set remote-mips64-transfers-32bit-regs
23968@kindex set remote-mips64-transfers-32bit-regs
eb17f351
EZ
23969This command controls compatibility with 64-bit @acronym{MIPS} targets that
23970transfer data in 32-bit quantities. If you have an old @acronym{MIPS} 64 target
a64548ea
EZ
23971that transfers 32 bits for some registers, like @sc{sr} and @sc{fsr},
23972and 64 bits for other registers, set this option to @samp{on}.
23973
23974@item show remote-mips64-transfers-32bit-regs
23975@kindex show remote-mips64-transfers-32bit-regs
eb17f351 23976Show the current setting of compatibility with older @acronym{MIPS} 64 targets.
a64548ea
EZ
23977
23978@item set debug mips
23979@kindex set debug mips
eb17f351 23980This command turns on and off debugging messages for the @acronym{MIPS}-specific
a64548ea
EZ
23981target code in @value{GDBN}.
23982
23983@item show debug mips
23984@kindex show debug mips
eb17f351 23985Show the current setting of @acronym{MIPS} debugging messages.
a64548ea
EZ
23986@end table
23987
23988
23989@node HPPA
23990@subsection HPPA
23991@cindex HPPA support
23992
d3e8051b 23993When @value{GDBN} is debugging the HP PA architecture, it provides the
a64548ea
EZ
23994following special commands:
23995
23996@table @code
23997@item set debug hppa
23998@kindex set debug hppa
db2e3e2e 23999This command determines whether HPPA architecture-specific debugging
a64548ea
EZ
24000messages are to be displayed.
24001
24002@item show debug hppa
24003Show whether HPPA debugging messages are displayed.
24004
24005@item maint print unwind @var{address}
24006@kindex maint print unwind@r{, HPPA}
24007This command displays the contents of the unwind table entry at the
24008given @var{address}.
24009
24010@end table
24011
104c1213 24012
23d964e7
UW
24013@node SPU
24014@subsection Cell Broadband Engine SPU architecture
24015@cindex Cell Broadband Engine
24016@cindex SPU
24017
24018When @value{GDBN} is debugging the Cell Broadband Engine SPU architecture,
24019it provides the following special commands:
24020
24021@table @code
24022@item info spu event
24023@kindex info spu
24024Display SPU event facility status. Shows current event mask
24025and pending event status.
24026
24027@item info spu signal
24028Display SPU signal notification facility status. Shows pending
24029signal-control word and signal notification mode of both signal
24030notification channels.
24031
24032@item info spu mailbox
24033Display SPU mailbox facility status. Shows all pending entries,
24034in order of processing, in each of the SPU Write Outbound,
24035SPU Write Outbound Interrupt, and SPU Read Inbound mailboxes.
24036
24037@item info spu dma
24038Display MFC DMA status. Shows all pending commands in the MFC
24039DMA queue. For each entry, opcode, tag, class IDs, effective
24040and local store addresses and transfer size are shown.
24041
24042@item info spu proxydma
24043Display MFC Proxy-DMA status. Shows all pending commands in the MFC
24044Proxy-DMA queue. For each entry, opcode, tag, class IDs, effective
24045and local store addresses and transfer size are shown.
24046
24047@end table
24048
3285f3fe
UW
24049When @value{GDBN} is debugging a combined PowerPC/SPU application
24050on the Cell Broadband Engine, it provides in addition the following
24051special commands:
24052
24053@table @code
24054@item set spu stop-on-load @var{arg}
24055@kindex set spu
24056Set whether to stop for new SPE threads. When set to @code{on}, @value{GDBN}
24057will give control to the user when a new SPE thread enters its @code{main}
24058function. The default is @code{off}.
24059
24060@item show spu stop-on-load
24061@kindex show spu
24062Show whether to stop for new SPE threads.
24063
ff1a52c6
UW
24064@item set spu auto-flush-cache @var{arg}
24065Set whether to automatically flush the software-managed cache. When set to
24066@code{on}, @value{GDBN} will automatically cause the SPE software-managed
24067cache to be flushed whenever SPE execution stops. This provides a consistent
24068view of PowerPC memory that is accessed via the cache. If an application
24069does not use the software-managed cache, this option has no effect.
24070
24071@item show spu auto-flush-cache
24072Show whether to automatically flush the software-managed cache.
24073
3285f3fe
UW
24074@end table
24075
4acd40f3
TJB
24076@node PowerPC
24077@subsection PowerPC
24078@cindex PowerPC architecture
24079
24080When @value{GDBN} is debugging the PowerPC architecture, it provides a set of
24081pseudo-registers to enable inspection of 128-bit wide Decimal Floating Point
24082numbers stored in the floating point registers. These values must be stored
24083in two consecutive registers, always starting at an even register like
24084@code{f0} or @code{f2}.
24085
24086The pseudo-registers go from @code{$dl0} through @code{$dl15}, and are formed
24087by joining the even/odd register pairs @code{f0} and @code{f1} for @code{$dl0},
24088@code{f2} and @code{f3} for @code{$dl1} and so on.
24089
aeac0ff9 24090For POWER7 processors, @value{GDBN} provides a set of pseudo-registers, the 64-bit
677c5bb1
LM
24091wide Extended Floating Point Registers (@samp{f32} through @samp{f63}).
24092
a1217d97
SL
24093@node Nios II
24094@subsection Nios II
24095@cindex Nios II architecture
24096
24097When @value{GDBN} is debugging the Nios II architecture,
24098it provides the following special commands:
24099
24100@table @code
24101
24102@item set debug nios2
24103@kindex set debug nios2
24104This command turns on and off debugging messages for the Nios II
24105target code in @value{GDBN}.
24106
24107@item show debug nios2
24108@kindex show debug nios2
24109Show the current setting of Nios II debugging messages.
24110@end table
23d964e7 24111
58afddc6
WP
24112@node Sparc64
24113@subsection Sparc64
24114@cindex Sparc64 support
24115@cindex Application Data Integrity
24116@subsubsection ADI Support
24117
24118The M7 processor supports an Application Data Integrity (ADI) feature that
24119detects invalid data accesses. When software allocates memory and enables
24120ADI on the allocated memory, it chooses a 4-bit version number, sets the
24121version in the upper 4 bits of the 64-bit pointer to that data, and stores
24122the 4-bit version in every cacheline of that data. Hardware saves the latter
24123in spare bits in the cache and memory hierarchy. On each load and store,
24124the processor compares the upper 4 VA (virtual address) bits to the
24125cacheline's version. If there is a mismatch, the processor generates a
24126version mismatch trap which can be either precise or disrupting. The trap
24127is an error condition which the kernel delivers to the process as a SIGSEGV
24128signal.
24129
24130Note that only 64-bit applications can use ADI and need to be built with
24131ADI-enabled.
24132
24133Values of the ADI version tags, which are in granularity of a
24134cacheline (64 bytes), can be viewed or modified.
24135
24136
24137@table @code
24138@kindex adi examine
24139@item adi (examine | x) [ / @var{n} ] @var{addr}
24140
24141The @code{adi examine} command displays the value of one ADI version tag per
24142cacheline.
24143
24144@var{n} is a decimal integer specifying the number in bytes; the default
24145is 1. It specifies how much ADI version information, at the ratio of 1:ADI
24146block size, to display.
24147
24148@var{addr} is the address in user address space where you want @value{GDBN}
24149to begin displaying the ADI version tags.
24150
24151Below is an example of displaying ADI versions of variable "shmaddr".
24152
24153@smallexample
24154(@value{GDBP}) adi x/100 shmaddr
24155 0xfff800010002c000: 0 0
24156@end smallexample
24157
24158@kindex adi assign
24159@item adi (assign | a) [ / @var{n} ] @var{addr} = @var{tag}
24160
24161The @code{adi assign} command is used to assign new ADI version tag
24162to an address.
24163
24164@var{n} is a decimal integer specifying the number in bytes;
24165the default is 1. It specifies how much ADI version information, at the
24166ratio of 1:ADI block size, to modify.
24167
24168@var{addr} is the address in user address space where you want @value{GDBN}
24169to begin modifying the ADI version tags.
24170
24171@var{tag} is the new ADI version tag.
24172
24173For example, do the following to modify then verify ADI versions of
24174variable "shmaddr":
24175
24176@smallexample
24177(@value{GDBP}) adi a/100 shmaddr = 7
24178(@value{GDBP}) adi x/100 shmaddr
24179 0xfff800010002c000: 7 7
24180@end smallexample
24181
24182@end table
24183
51d21d60
JD
24184@node S12Z
24185@subsection S12Z
24186@cindex S12Z support
24187
24188When @value{GDBN} is debugging the S12Z architecture,
24189it provides the following special command:
24190
24191@table @code
24192@item maint info bdccsr
24193@kindex maint info bdccsr@r{, S12Z}
24194This command displays the current value of the microprocessor's
24195BDCCSR register.
24196@end table
24197
24198
8e04817f
AC
24199@node Controlling GDB
24200@chapter Controlling @value{GDBN}
24201
24202You can alter the way @value{GDBN} interacts with you by using the
24203@code{set} command. For commands controlling how @value{GDBN} displays
79a6e687 24204data, see @ref{Print Settings, ,Print Settings}. Other settings are
8e04817f
AC
24205described here.
24206
24207@menu
24208* Prompt:: Prompt
24209* Editing:: Command editing
d620b259 24210* Command History:: Command history
8e04817f 24211* Screen Size:: Screen size
140a4bc0 24212* Output Styling:: Output styling
8e04817f 24213* Numbers:: Numbers
1e698235 24214* ABI:: Configuring the current ABI
bf88dd68 24215* Auto-loading:: Automatically loading associated files
8e04817f
AC
24216* Messages/Warnings:: Optional warnings and messages
24217* Debugging Output:: Optional messages about internal happenings
14fb1bac 24218* Other Misc Settings:: Other Miscellaneous Settings
8e04817f
AC
24219@end menu
24220
24221@node Prompt
24222@section Prompt
104c1213 24223
8e04817f 24224@cindex prompt
104c1213 24225
8e04817f
AC
24226@value{GDBN} indicates its readiness to read a command by printing a string
24227called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You
24228can change the prompt string with the @code{set prompt} command. For
24229instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change
24230the prompt in one of the @value{GDBN} sessions so that you can always tell
24231which one you are talking to.
104c1213 24232
8e04817f
AC
24233@emph{Note:} @code{set prompt} does not add a space for you after the
24234prompt you set. This allows you to set a prompt which ends in a space
24235or a prompt that does not.
104c1213 24236
8e04817f
AC
24237@table @code
24238@kindex set prompt
24239@item set prompt @var{newprompt}
24240Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth.
104c1213 24241
8e04817f
AC
24242@kindex show prompt
24243@item show prompt
24244Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
104c1213
JM
24245@end table
24246
fa3a4f15
PM
24247Versions of @value{GDBN} that ship with Python scripting enabled have
24248prompt extensions. The commands for interacting with these extensions
24249are:
24250
24251@table @code
24252@kindex set extended-prompt
24253@item set extended-prompt @var{prompt}
24254Set an extended prompt that allows for substitutions.
24255@xref{gdb.prompt}, for a list of escape sequences that can be used for
24256substitution. Any escape sequences specified as part of the prompt
24257string are replaced with the corresponding strings each time the prompt
24258is displayed.
24259
24260For example:
24261
24262@smallexample
24263set extended-prompt Current working directory: \w (gdb)
24264@end smallexample
24265
24266Note that when an extended-prompt is set, it takes control of the
24267@var{prompt_hook} hook. @xref{prompt_hook}, for further information.
24268
24269@kindex show extended-prompt
24270@item show extended-prompt
24271Prints the extended prompt. Any escape sequences specified as part of
24272the prompt string with @code{set extended-prompt}, are replaced with the
24273corresponding strings each time the prompt is displayed.
24274@end table
24275
8e04817f 24276@node Editing
79a6e687 24277@section Command Editing
8e04817f
AC
24278@cindex readline
24279@cindex command line editing
104c1213 24280
703663ab 24281@value{GDBN} reads its input commands via the @dfn{Readline} interface. This
8e04817f
AC
24282@sc{gnu} library provides consistent behavior for programs which provide a
24283command line interface to the user. Advantages are @sc{gnu} Emacs-style
24284or @dfn{vi}-style inline editing of commands, @code{csh}-like history
24285substitution, and a storage and recall of command history across
24286debugging sessions.
104c1213 24287
8e04817f
AC
24288You may control the behavior of command line editing in @value{GDBN} with the
24289command @code{set}.
104c1213 24290
8e04817f
AC
24291@table @code
24292@kindex set editing
24293@cindex editing
24294@item set editing
24295@itemx set editing on
24296Enable command line editing (enabled by default).
104c1213 24297
8e04817f
AC
24298@item set editing off
24299Disable command line editing.
104c1213 24300
8e04817f
AC
24301@kindex show editing
24302@item show editing
24303Show whether command line editing is enabled.
104c1213
JM
24304@end table
24305
39037522
TT
24306@ifset SYSTEM_READLINE
24307@xref{Command Line Editing, , , rluserman, GNU Readline Library},
24308@end ifset
24309@ifclear SYSTEM_READLINE
24310@xref{Command Line Editing},
24311@end ifclear
24312for more details about the Readline
703663ab
EZ
24313interface. Users unfamiliar with @sc{gnu} Emacs or @code{vi} are
24314encouraged to read that chapter.
24315
d620b259 24316@node Command History
79a6e687 24317@section Command History
703663ab 24318@cindex command history
8e04817f
AC
24319
24320@value{GDBN} can keep track of the commands you type during your
24321debugging sessions, so that you can be certain of precisely what
24322happened. Use these commands to manage the @value{GDBN} command
24323history facility.
104c1213 24324
703663ab 24325@value{GDBN} uses the @sc{gnu} History library, a part of the Readline
39037522
TT
24326package, to provide the history facility.
24327@ifset SYSTEM_READLINE
24328@xref{Using History Interactively, , , history, GNU History Library},
24329@end ifset
24330@ifclear SYSTEM_READLINE
24331@xref{Using History Interactively},
24332@end ifclear
24333for the detailed description of the History library.
703663ab 24334
d620b259 24335To issue a command to @value{GDBN} without affecting certain aspects of
9e6c4bd5
NR
24336the state which is seen by users, prefix it with @samp{server }
24337(@pxref{Server Prefix}). This
d620b259
NR
24338means that this command will not affect the command history, nor will it
24339affect @value{GDBN}'s notion of which command to repeat if @key{RET} is
24340pressed on a line by itself.
24341
24342@cindex @code{server}, command prefix
24343The server prefix does not affect the recording of values into the value
24344history; to print a value without recording it into the value history,
24345use the @code{output} command instead of the @code{print} command.
24346
703663ab
EZ
24347Here is the description of @value{GDBN} commands related to command
24348history.
24349
104c1213 24350@table @code
8e04817f
AC
24351@cindex history substitution
24352@cindex history file
24353@kindex set history filename
4644b6e3 24354@cindex @env{GDBHISTFILE}, environment variable
8e04817f
AC
24355@item set history filename @var{fname}
24356Set the name of the @value{GDBN} command history file to @var{fname}.
24357This is the file where @value{GDBN} reads an initial command history
24358list, and where it writes the command history from this session when it
24359exits. You can access this list through history expansion or through
24360the history command editing characters listed below. This file defaults
24361to the value of the environment variable @code{GDBHISTFILE}, or to
24362@file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable
24363is not set.
104c1213 24364
9c16f35a
EZ
24365@cindex save command history
24366@kindex set history save
8e04817f
AC
24367@item set history save
24368@itemx set history save on
24369Record command history in a file, whose name may be specified with the
24370@code{set history filename} command. By default, this option is disabled.
104c1213 24371
8e04817f
AC
24372@item set history save off
24373Stop recording command history in a file.
104c1213 24374
8e04817f 24375@cindex history size
9c16f35a 24376@kindex set history size
b58c513b 24377@cindex @env{GDBHISTSIZE}, environment variable
8e04817f 24378@item set history size @var{size}
f81d1120 24379@itemx set history size unlimited
8e04817f 24380Set the number of commands which @value{GDBN} keeps in its history list.
bc460514
PP
24381This defaults to the value of the environment variable @env{GDBHISTSIZE}, or
24382to 256 if this variable is not set. Non-numeric values of @env{GDBHISTSIZE}
0eacb298
PP
24383are ignored. If @var{size} is @code{unlimited} or if @env{GDBHISTSIZE} is
24384either a negative number or the empty string, then the number of commands
24385@value{GDBN} keeps in the history list is unlimited.
fc637f04
PP
24386
24387@cindex remove duplicate history
24388@kindex set history remove-duplicates
24389@item set history remove-duplicates @var{count}
24390@itemx set history remove-duplicates unlimited
24391Control the removal of duplicate history entries in the command history list.
24392If @var{count} is non-zero, @value{GDBN} will look back at the last @var{count}
24393history entries and remove the first entry that is a duplicate of the current
24394entry being added to the command history list. If @var{count} is
24395@code{unlimited} then this lookbehind is unbounded. If @var{count} is 0, then
24396removal of duplicate history entries is disabled.
24397
24398Only history entries added during the current session are considered for
24399removal. This option is set to 0 by default.
24400
104c1213
JM
24401@end table
24402
8e04817f 24403History expansion assigns special meaning to the character @kbd{!}.
39037522
TT
24404@ifset SYSTEM_READLINE
24405@xref{Event Designators, , , history, GNU History Library},
24406@end ifset
24407@ifclear SYSTEM_READLINE
24408@xref{Event Designators},
24409@end ifclear
24410for more details.
8e04817f 24411
703663ab 24412@cindex history expansion, turn on/off
8e04817f
AC
24413Since @kbd{!} is also the logical not operator in C, history expansion
24414is off by default. If you decide to enable history expansion with the
24415@code{set history expansion on} command, you may sometimes need to
24416follow @kbd{!} (when it is used as logical not, in an expression) with
24417a space or a tab to prevent it from being expanded. The readline
24418history facilities do not attempt substitution on the strings
24419@kbd{!=} and @kbd{!(}, even when history expansion is enabled.
24420
24421The commands to control history expansion are:
104c1213
JM
24422
24423@table @code
8e04817f
AC
24424@item set history expansion on
24425@itemx set history expansion
703663ab 24426@kindex set history expansion
8e04817f 24427Enable history expansion. History expansion is off by default.
104c1213 24428
8e04817f
AC
24429@item set history expansion off
24430Disable history expansion.
104c1213 24431
8e04817f
AC
24432@c @group
24433@kindex show history
24434@item show history
24435@itemx show history filename
24436@itemx show history save
24437@itemx show history size
24438@itemx show history expansion
24439These commands display the state of the @value{GDBN} history parameters.
24440@code{show history} by itself displays all four states.
24441@c @end group
24442@end table
24443
24444@table @code
9c16f35a
EZ
24445@kindex show commands
24446@cindex show last commands
24447@cindex display command history
8e04817f
AC
24448@item show commands
24449Display the last ten commands in the command history.
104c1213 24450
8e04817f
AC
24451@item show commands @var{n}
24452Print ten commands centered on command number @var{n}.
24453
24454@item show commands +
24455Print ten commands just after the commands last printed.
104c1213
JM
24456@end table
24457
8e04817f 24458@node Screen Size
79a6e687 24459@section Screen Size
8e04817f 24460@cindex size of screen
f179cf97
EZ
24461@cindex screen size
24462@cindex pagination
24463@cindex page size
8e04817f 24464@cindex pauses in output
104c1213 24465
8e04817f
AC
24466Certain commands to @value{GDBN} may produce large amounts of
24467information output to the screen. To help you read all of it,
24468@value{GDBN} pauses and asks you for input at the end of each page of
eb6af809
TT
24469output. Type @key{RET} when you want to see one more page of output,
24470@kbd{q} to discard the remaining output, or @kbd{c} to continue
24471without paging for the rest of the current command. Also, the screen
24472width setting determines when to wrap lines of output. Depending on
24473what is being printed, @value{GDBN} tries to break the line at a
24474readable place, rather than simply letting it overflow onto the
24475following line.
8e04817f
AC
24476
24477Normally @value{GDBN} knows the size of the screen from the terminal
24478driver software. For example, on Unix @value{GDBN} uses the termcap data base
24479together with the value of the @code{TERM} environment variable and the
24480@code{stty rows} and @code{stty cols} settings. If this is not correct,
24481you can override it with the @code{set height} and @code{set
24482width} commands:
24483
24484@table @code
24485@kindex set height
24486@kindex set width
24487@kindex show width
24488@kindex show height
24489@item set height @var{lpp}
f81d1120 24490@itemx set height unlimited
8e04817f
AC
24491@itemx show height
24492@itemx set width @var{cpl}
f81d1120 24493@itemx set width unlimited
8e04817f
AC
24494@itemx show width
24495These @code{set} commands specify a screen height of @var{lpp} lines and
24496a screen width of @var{cpl} characters. The associated @code{show}
24497commands display the current settings.
104c1213 24498
f81d1120
PA
24499If you specify a height of either @code{unlimited} or zero lines,
24500@value{GDBN} does not pause during output no matter how long the
24501output is. This is useful if output is to a file or to an editor
24502buffer.
104c1213 24503
f81d1120
PA
24504Likewise, you can specify @samp{set width unlimited} or @samp{set
24505width 0} to prevent @value{GDBN} from wrapping its output.
9c16f35a
EZ
24506
24507@item set pagination on
24508@itemx set pagination off
24509@kindex set pagination
24510Turn the output pagination on or off; the default is on. Turning
f81d1120 24511pagination off is the alternative to @code{set height unlimited}. Note that
7c953934
TT
24512running @value{GDBN} with the @option{--batch} option (@pxref{Mode
24513Options, -batch}) also automatically disables pagination.
9c16f35a
EZ
24514
24515@item show pagination
24516@kindex show pagination
24517Show the current pagination mode.
104c1213
JM
24518@end table
24519
140a4bc0
TT
24520@node Output Styling
24521@section Output Styling
24522@cindex styling
24523@cindex colors
24524
24525@kindex set style
24526@kindex show style
24527@value{GDBN} can style its output on a capable terminal. This is
7557a514
AH
24528enabled by default on most systems, but disabled by default when in
24529batch mode (@pxref{Mode Options}). Various style settings are available;
24530and styles can also be disabled entirely.
140a4bc0
TT
24531
24532@table @code
24533@item set style enabled @samp{on|off}
24534Enable or disable all styling. The default is host-dependent, with
24535most hosts defaulting to @samp{on}.
24536
24537@item show style enabled
24538Show the current state of styling.
d085f989
TT
24539
24540@item set style sources @samp{on|off}
24541Enable or disable source code styling. This affects whether source
24542code, such as the output of the @code{list} command, is styled. Note
24543that source styling only works if styling in general is enabled, and
24544if @value{GDBN} was linked with the GNU Source Highlight library. The
24545default is @samp{on}.
24546
24547@item show style sources
24548Show the current state of source code styling.
140a4bc0
TT
24549@end table
24550
24551Subcommands of @code{set style} control specific forms of styling.
24552These subcommands all follow the same pattern: each style-able object
24553can be styled with a foreground color, a background color, and an
24554intensity.
24555
24556For example, the style of file names can be controlled using the
24557@code{set style filename} group of commands:
24558
24559@table @code
24560@item set style filename background @var{color}
24561Set the background to @var{color}. Valid colors are @samp{none}
24562(meaning the terminal's default color), @samp{black}, @samp{red},
e3624a40 24563@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
140a4bc0
TT
24564and@samp{white}.
24565
24566@item set style filename foreground @var{color}
24567Set the foreground to @var{color}. Valid colors are @samp{none}
24568(meaning the terminal's default color), @samp{black}, @samp{red},
e3624a40 24569@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
140a4bc0
TT
24570and@samp{white}.
24571
24572@item set style filename intensity @var{value}
24573Set the intensity to @var{value}. Valid intensities are @samp{normal}
24574(the default), @samp{bold}, and @samp{dim}.
24575@end table
24576
24577The style-able objects are:
24578@table @code
24579@item filename
e3624a40
EZ
24580Control the styling of file names. By default, this style's
24581foreground color is green.
140a4bc0
TT
24582
24583@item function
24584Control the styling of function names. These are managed with the
e3624a40
EZ
24585@code{set style function} family of commands. By default, this
24586style's foreground color is yellow.
140a4bc0
TT
24587
24588@item variable
24589Control the styling of variable names. These are managed with the
e3624a40
EZ
24590@code{set style variable} family of commands. By default, this style's
24591foreground color is cyan.
140a4bc0
TT
24592
24593@item address
24594Control the styling of addresses. These are managed with the
e3624a40
EZ
24595@code{set style address} family of commands. By default, this style's
24596foreground color is blue.
140a4bc0
TT
24597@end table
24598
8e04817f
AC
24599@node Numbers
24600@section Numbers
24601@cindex number representation
24602@cindex entering numbers
104c1213 24603
8e04817f
AC
24604You can always enter numbers in octal, decimal, or hexadecimal in
24605@value{GDBN} by the usual conventions: octal numbers begin with
24606@samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers
eb2dae08
EZ
24607begin with @samp{0x}. Numbers that neither begin with @samp{0} or
24608@samp{0x}, nor end with a @samp{.} are, by default, entered in base
2460910; likewise, the default display for numbers---when no particular
24610format is specified---is base 10. You can change the default base for
24611both input and output with the commands described below.
104c1213 24612
8e04817f
AC
24613@table @code
24614@kindex set input-radix
24615@item set input-radix @var{base}
24616Set the default base for numeric input. Supported choices
697aa1b7 24617for @var{base} are decimal 8, 10, or 16. The base must itself be
eb2dae08 24618specified either unambiguously or using the current input radix; for
8e04817f 24619example, any of
104c1213 24620
8e04817f 24621@smallexample
9c16f35a
EZ
24622set input-radix 012
24623set input-radix 10.
24624set input-radix 0xa
8e04817f 24625@end smallexample
104c1213 24626
8e04817f 24627@noindent
9c16f35a 24628sets the input base to decimal. On the other hand, @samp{set input-radix 10}
eb2dae08
EZ
24629leaves the input radix unchanged, no matter what it was, since
24630@samp{10}, being without any leading or trailing signs of its base, is
24631interpreted in the current radix. Thus, if the current radix is 16,
24632@samp{10} is interpreted in hex, i.e.@: as 16 decimal, which doesn't
24633change the radix.
104c1213 24634
8e04817f
AC
24635@kindex set output-radix
24636@item set output-radix @var{base}
24637Set the default base for numeric display. Supported choices
697aa1b7 24638for @var{base} are decimal 8, 10, or 16. The base must itself be
eb2dae08 24639specified either unambiguously or using the current input radix.
104c1213 24640
8e04817f
AC
24641@kindex show input-radix
24642@item show input-radix
24643Display the current default base for numeric input.
104c1213 24644
8e04817f
AC
24645@kindex show output-radix
24646@item show output-radix
24647Display the current default base for numeric display.
9c16f35a
EZ
24648
24649@item set radix @r{[}@var{base}@r{]}
24650@itemx show radix
24651@kindex set radix
24652@kindex show radix
24653These commands set and show the default base for both input and output
24654of numbers. @code{set radix} sets the radix of input and output to
24655the same base; without an argument, it resets the radix back to its
24656default value of 10.
24657
8e04817f 24658@end table
104c1213 24659
1e698235 24660@node ABI
79a6e687 24661@section Configuring the Current ABI
1e698235
DJ
24662
24663@value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your
24664application automatically. However, sometimes you need to override its
24665conclusions. Use these commands to manage @value{GDBN}'s view of the
24666current ABI.
24667
98b45e30
DJ
24668@cindex OS ABI
24669@kindex set osabi
b4e9345d 24670@kindex show osabi
430ed3f0 24671@cindex Newlib OS ABI and its influence on the longjmp handling
98b45e30
DJ
24672
24673One @value{GDBN} configuration can debug binaries for multiple operating
b383017d 24674system targets, either via remote debugging or native emulation.
98b45e30
DJ
24675@value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use,
24676but you can override its conclusion using the @code{set osabi} command.
24677One example where this is useful is in debugging of binaries which use
24678an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does
24679not have the same identifying marks that the standard C library for your
24680platform provides.
24681
430ed3f0
MS
24682When @value{GDBN} is debugging the AArch64 architecture, it provides a
24683``Newlib'' OS ABI. This is useful for handling @code{setjmp} and
24684@code{longjmp} when debugging binaries that use the @sc{newlib} C library.
24685The ``Newlib'' OS ABI can be selected by @code{set osabi Newlib}.
24686
98b45e30
DJ
24687@table @code
24688@item show osabi
24689Show the OS ABI currently in use.
24690
24691@item set osabi
24692With no argument, show the list of registered available OS ABI's.
24693
24694@item set osabi @var{abi}
24695Set the current OS ABI to @var{abi}.
24696@end table
24697
1e698235 24698@cindex float promotion
1e698235
DJ
24699
24700Generally, the way that an argument of type @code{float} is passed to a
24701function depends on whether the function is prototyped. For a prototyped
24702(i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged,
24703according to the architecture's convention for @code{float}. For unprototyped
24704(i.e.@: K&R style) functions, @code{float} arguments are first promoted to type
24705@code{double} and then passed.
24706
24707Unfortunately, some forms of debug information do not reliably indicate whether
24708a function is prototyped. If @value{GDBN} calls a function that is not marked
24709as prototyped, it consults @kbd{set coerce-float-to-double}.
24710
24711@table @code
a8f24a35 24712@kindex set coerce-float-to-double
1e698235
DJ
24713@item set coerce-float-to-double
24714@itemx set coerce-float-to-double on
24715Arguments of type @code{float} will be promoted to @code{double} when passed
24716to an unprototyped function. This is the default setting.
24717
24718@item set coerce-float-to-double off
24719Arguments of type @code{float} will be passed directly to unprototyped
24720functions.
9c16f35a
EZ
24721
24722@kindex show coerce-float-to-double
24723@item show coerce-float-to-double
24724Show the current setting of promoting @code{float} to @code{double}.
1e698235
DJ
24725@end table
24726
f1212245
DJ
24727@kindex set cp-abi
24728@kindex show cp-abi
24729@value{GDBN} needs to know the ABI used for your program's C@t{++}
24730objects. The correct C@t{++} ABI depends on which C@t{++} compiler was
24731used to build your application. @value{GDBN} only fully supports
24732programs with a single C@t{++} ABI; if your program contains code using
24733multiple C@t{++} ABI's or if @value{GDBN} can not identify your
24734program's ABI correctly, you can tell @value{GDBN} which ABI to use.
24735Currently supported ABI's include ``gnu-v2'', for @code{g++} versions
24736before 3.0, ``gnu-v3'', for @code{g++} versions 3.0 and later, and
24737``hpaCC'' for the HP ANSI C@t{++} compiler. Other C@t{++} compilers may
24738use the ``gnu-v2'' or ``gnu-v3'' ABI's as well. The default setting is
24739``auto''.
24740
24741@table @code
24742@item show cp-abi
24743Show the C@t{++} ABI currently in use.
24744
24745@item set cp-abi
24746With no argument, show the list of supported C@t{++} ABI's.
24747
24748@item set cp-abi @var{abi}
24749@itemx set cp-abi auto
24750Set the current C@t{++} ABI to @var{abi}, or return to automatic detection.
24751@end table
24752
bf88dd68
JK
24753@node Auto-loading
24754@section Automatically loading associated files
24755@cindex auto-loading
24756
24757@value{GDBN} sometimes reads files with commands and settings automatically,
24758without being explicitly told so by the user. We call this feature
24759@dfn{auto-loading}. While auto-loading is useful for automatically adapting
24760@value{GDBN} to the needs of your project, it can sometimes produce unexpected
24761results or introduce security risks (e.g., if the file comes from untrusted
24762sources).
24763
71b8c845
DE
24764@menu
24765* Init File in the Current Directory:: @samp{set/show/info auto-load local-gdbinit}
24766* libthread_db.so.1 file:: @samp{set/show/info auto-load libthread-db}
24767
24768* Auto-loading safe path:: @samp{set/show/info auto-load safe-path}
24769* Auto-loading verbose mode:: @samp{set/show debug auto-load}
24770@end menu
24771
24772There are various kinds of files @value{GDBN} can automatically load.
24773In addition to these files, @value{GDBN} supports auto-loading code written
24774in various extension languages. @xref{Auto-loading extensions}.
24775
c1668e4e
JK
24776Note that loading of these associated files (including the local @file{.gdbinit}
24777file) requires accordingly configured @code{auto-load safe-path}
24778(@pxref{Auto-loading safe path}).
24779
bf88dd68
JK
24780For these reasons, @value{GDBN} includes commands and options to let you
24781control when to auto-load files and which files should be auto-loaded.
24782
24783@table @code
24784@anchor{set auto-load off}
24785@kindex set auto-load off
24786@item set auto-load off
24787Globally disable loading of all auto-loaded files.
24788You may want to use this command with the @samp{-iex} option
24789(@pxref{Option -init-eval-command}) such as:
24790@smallexample
24791$ @kbd{gdb -iex "set auto-load off" untrusted-executable corefile}
24792@end smallexample
24793
24794Be aware that system init file (@pxref{System-wide configuration})
24795and init files from your home directory (@pxref{Home Directory Init File})
24796still get read (as they come from generally trusted directories).
24797To prevent @value{GDBN} from auto-loading even those init files, use the
24798@option{-nx} option (@pxref{Mode Options}), in addition to
24799@code{set auto-load no}.
24800
24801@anchor{show auto-load}
24802@kindex show auto-load
24803@item show auto-load
24804Show whether auto-loading of each specific @samp{auto-load} file(s) is enabled
24805or disabled.
24806
24807@smallexample
24808(gdb) show auto-load
24809gdb-scripts: Auto-loading of canned sequences of commands scripts is on.
24810libthread-db: Auto-loading of inferior specific libthread_db is on.
1ccacbcd
JK
24811local-gdbinit: Auto-loading of .gdbinit script from current directory
24812 is on.
bf88dd68 24813python-scripts: Auto-loading of Python scripts is on.
bccbefd2 24814safe-path: List of directories from which it is safe to auto-load files
1564a261 24815 is $debugdir:$datadir/auto-load.
7349ff92 24816scripts-directory: List of directories from which to load auto-loaded scripts
1564a261 24817 is $debugdir:$datadir/auto-load.
bf88dd68
JK
24818@end smallexample
24819
24820@anchor{info auto-load}
24821@kindex info auto-load
24822@item info auto-load
24823Print whether each specific @samp{auto-load} file(s) have been auto-loaded or
24824not.
24825
24826@smallexample
24827(gdb) info auto-load
24828gdb-scripts:
24829Loaded Script
24830Yes /home/user/gdb/gdb-gdb.gdb
24831libthread-db: No auto-loaded libthread-db.
1ccacbcd
JK
24832local-gdbinit: Local .gdbinit file "/home/user/gdb/.gdbinit" has been
24833 loaded.
bf88dd68
JK
24834python-scripts:
24835Loaded Script
24836Yes /home/user/gdb/gdb-gdb.py
24837@end smallexample
24838@end table
24839
bf88dd68
JK
24840These are @value{GDBN} control commands for the auto-loading:
24841
24842@multitable @columnfractions .5 .5
24843@item @xref{set auto-load off}.
24844@tab Disable auto-loading globally.
24845@item @xref{show auto-load}.
24846@tab Show setting of all kinds of files.
24847@item @xref{info auto-load}.
24848@tab Show state of all kinds of files.
24849@item @xref{set auto-load gdb-scripts}.
24850@tab Control for @value{GDBN} command scripts.
24851@item @xref{show auto-load gdb-scripts}.
24852@tab Show setting of @value{GDBN} command scripts.
24853@item @xref{info auto-load gdb-scripts}.
24854@tab Show state of @value{GDBN} command scripts.
24855@item @xref{set auto-load python-scripts}.
24856@tab Control for @value{GDBN} Python scripts.
24857@item @xref{show auto-load python-scripts}.
24858@tab Show setting of @value{GDBN} Python scripts.
24859@item @xref{info auto-load python-scripts}.
24860@tab Show state of @value{GDBN} Python scripts.
ed3ef339
DE
24861@item @xref{set auto-load guile-scripts}.
24862@tab Control for @value{GDBN} Guile scripts.
24863@item @xref{show auto-load guile-scripts}.
24864@tab Show setting of @value{GDBN} Guile scripts.
24865@item @xref{info auto-load guile-scripts}.
24866@tab Show state of @value{GDBN} Guile scripts.
7349ff92
JK
24867@item @xref{set auto-load scripts-directory}.
24868@tab Control for @value{GDBN} auto-loaded scripts location.
24869@item @xref{show auto-load scripts-directory}.
24870@tab Show @value{GDBN} auto-loaded scripts location.
f10c5b19
JK
24871@item @xref{add-auto-load-scripts-directory}.
24872@tab Add directory for auto-loaded scripts location list.
bf88dd68
JK
24873@item @xref{set auto-load local-gdbinit}.
24874@tab Control for init file in the current directory.
24875@item @xref{show auto-load local-gdbinit}.
24876@tab Show setting of init file in the current directory.
24877@item @xref{info auto-load local-gdbinit}.
24878@tab Show state of init file in the current directory.
24879@item @xref{set auto-load libthread-db}.
24880@tab Control for thread debugging library.
24881@item @xref{show auto-load libthread-db}.
24882@tab Show setting of thread debugging library.
24883@item @xref{info auto-load libthread-db}.
24884@tab Show state of thread debugging library.
bccbefd2
JK
24885@item @xref{set auto-load safe-path}.
24886@tab Control directories trusted for automatic loading.
24887@item @xref{show auto-load safe-path}.
24888@tab Show directories trusted for automatic loading.
24889@item @xref{add-auto-load-safe-path}.
24890@tab Add directory trusted for automatic loading.
bf88dd68
JK
24891@end multitable
24892
bf88dd68
JK
24893@node Init File in the Current Directory
24894@subsection Automatically loading init file in the current directory
24895@cindex auto-loading init file in the current directory
24896
24897By default, @value{GDBN} reads and executes the canned sequences of commands
24898from init file (if any) in the current working directory,
24899see @ref{Init File in the Current Directory during Startup}.
24900
c1668e4e
JK
24901Note that loading of this local @file{.gdbinit} file also requires accordingly
24902configured @code{auto-load safe-path} (@pxref{Auto-loading safe path}).
24903
bf88dd68
JK
24904@table @code
24905@anchor{set auto-load local-gdbinit}
24906@kindex set auto-load local-gdbinit
24907@item set auto-load local-gdbinit [on|off]
24908Enable or disable the auto-loading of canned sequences of commands
24909(@pxref{Sequences}) found in init file in the current directory.
24910
24911@anchor{show auto-load local-gdbinit}
24912@kindex show auto-load local-gdbinit
24913@item show auto-load local-gdbinit
24914Show whether auto-loading of canned sequences of commands from init file in the
24915current directory is enabled or disabled.
24916
24917@anchor{info auto-load local-gdbinit}
24918@kindex info auto-load local-gdbinit
24919@item info auto-load local-gdbinit
24920Print whether canned sequences of commands from init file in the
24921current directory have been auto-loaded.
24922@end table
24923
24924@node libthread_db.so.1 file
24925@subsection Automatically loading thread debugging library
24926@cindex auto-loading libthread_db.so.1
24927
24928This feature is currently present only on @sc{gnu}/Linux native hosts.
24929
24930@value{GDBN} reads in some cases thread debugging library from places specific
24931to the inferior (@pxref{set libthread-db-search-path}).
24932
24933The special @samp{libthread-db-search-path} entry @samp{$sdir} is processed
24934without checking this @samp{set auto-load libthread-db} switch as system
24935libraries have to be trusted in general. In all other cases of
24936@samp{libthread-db-search-path} entries @value{GDBN} checks first if @samp{set
24937auto-load libthread-db} is enabled before trying to open such thread debugging
24938library.
24939
c1668e4e
JK
24940Note that loading of this debugging library also requires accordingly configured
24941@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
24942
bf88dd68
JK
24943@table @code
24944@anchor{set auto-load libthread-db}
24945@kindex set auto-load libthread-db
24946@item set auto-load libthread-db [on|off]
24947Enable or disable the auto-loading of inferior specific thread debugging library.
24948
24949@anchor{show auto-load libthread-db}
24950@kindex show auto-load libthread-db
24951@item show auto-load libthread-db
24952Show whether auto-loading of inferior specific thread debugging library is
24953enabled or disabled.
24954
24955@anchor{info auto-load libthread-db}
24956@kindex info auto-load libthread-db
24957@item info auto-load libthread-db
24958Print the list of all loaded inferior specific thread debugging libraries and
24959for each such library print list of inferior @var{pid}s using it.
24960@end table
24961
bccbefd2
JK
24962@node Auto-loading safe path
24963@subsection Security restriction for auto-loading
24964@cindex auto-loading safe-path
24965
24966As the files of inferior can come from untrusted source (such as submitted by
24967an application user) @value{GDBN} does not always load any files automatically.
24968@value{GDBN} provides the @samp{set auto-load safe-path} setting to list
24969directories trusted for loading files not explicitly requested by user.
202cbf1c 24970Each directory can also be a shell wildcard pattern.
bccbefd2
JK
24971
24972If the path is not set properly you will see a warning and the file will not
24973get loaded:
24974
24975@smallexample
24976$ ./gdb -q ./gdb
24977Reading symbols from /home/user/gdb/gdb...done.
24978warning: File "/home/user/gdb/gdb-gdb.gdb" auto-loading has been
1564a261
JK
24979 declined by your `auto-load safe-path' set
24980 to "$debugdir:$datadir/auto-load".
bccbefd2 24981warning: File "/home/user/gdb/gdb-gdb.py" auto-loading has been
1564a261
JK
24982 declined by your `auto-load safe-path' set
24983 to "$debugdir:$datadir/auto-load".
bccbefd2
JK
24984@end smallexample
24985
2c91021c
JK
24986@noindent
24987To instruct @value{GDBN} to go ahead and use the init files anyway,
24988invoke @value{GDBN} like this:
24989
24990@smallexample
24991$ gdb -q -iex "set auto-load safe-path /home/user/gdb" ./gdb
24992@end smallexample
24993
bccbefd2
JK
24994The list of trusted directories is controlled by the following commands:
24995
24996@table @code
24997@anchor{set auto-load safe-path}
24998@kindex set auto-load safe-path
af2c1515 24999@item set auto-load safe-path @r{[}@var{directories}@r{]}
bccbefd2
JK
25000Set the list of directories (and their subdirectories) trusted for automatic
25001loading and execution of scripts. You can also enter a specific trusted file.
202cbf1c
JK
25002Each directory can also be a shell wildcard pattern; wildcards do not match
25003directory separator - see @code{FNM_PATHNAME} for system function @code{fnmatch}
25004(@pxref{Wildcard Matching, fnmatch, , libc, GNU C Library Reference Manual}).
af2c1515
JK
25005If you omit @var{directories}, @samp{auto-load safe-path} will be reset to
25006its default value as specified during @value{GDBN} compilation.
25007
d9242c17 25008The list of directories uses path separator (@samp{:} on GNU and Unix
bccbefd2
JK
25009systems, @samp{;} on MS-Windows and MS-DOS) to separate directories, similarly
25010to the @env{PATH} environment variable.
25011
25012@anchor{show auto-load safe-path}
25013@kindex show auto-load safe-path
25014@item show auto-load safe-path
25015Show the list of directories trusted for automatic loading and execution of
25016scripts.
25017
25018@anchor{add-auto-load-safe-path}
25019@kindex add-auto-load-safe-path
25020@item add-auto-load-safe-path
413b59ae
JK
25021Add an entry (or list of entries) to the list of directories trusted for
25022automatic loading and execution of scripts. Multiple entries may be delimited
25023by the host platform path separator in use.
bccbefd2
JK
25024@end table
25025
7349ff92 25026This variable defaults to what @code{--with-auto-load-dir} has been configured
1564a261
JK
25027to (@pxref{with-auto-load-dir}). @file{$debugdir} and @file{$datadir}
25028substitution applies the same as for @ref{set auto-load scripts-directory}.
25029The default @code{set auto-load safe-path} value can be also overriden by
25030@value{GDBN} configuration option @option{--with-auto-load-safe-path}.
6dea1fbd 25031
6dea1fbd
JK
25032Setting this variable to @file{/} disables this security protection,
25033corresponding @value{GDBN} configuration option is
25034@option{--without-auto-load-safe-path}.
bccbefd2
JK
25035This variable is supposed to be set to the system directories writable by the
25036system superuser only. Users can add their source directories in init files in
25037their home directories (@pxref{Home Directory Init File}). See also deprecated
25038init file in the current directory
25039(@pxref{Init File in the Current Directory during Startup}).
25040
25041To force @value{GDBN} to load the files it declined to load in the previous
25042example, you could use one of the following ways:
25043
0511cc75
JK
25044@table @asis
25045@item @file{~/.gdbinit}: @samp{add-auto-load-safe-path ~/src/gdb}
bccbefd2
JK
25046Specify this trusted directory (or a file) as additional component of the list.
25047You have to specify also any existing directories displayed by
25048by @samp{show auto-load safe-path} (such as @samp{/usr:/bin} in this example).
25049
174bb630 25050@item @kbd{gdb -iex "set auto-load safe-path /usr:/bin:~/src/gdb" @dots{}}
bccbefd2
JK
25051Specify this directory as in the previous case but just for a single
25052@value{GDBN} session.
25053
af2c1515 25054@item @kbd{gdb -iex "set auto-load safe-path /" @dots{}}
bccbefd2
JK
25055Disable auto-loading safety for a single @value{GDBN} session.
25056This assumes all the files you debug during this @value{GDBN} session will come
25057from trusted sources.
25058
25059@item @kbd{./configure --without-auto-load-safe-path}
25060During compilation of @value{GDBN} you may disable any auto-loading safety.
25061This assumes all the files you will ever debug with this @value{GDBN} come from
25062trusted sources.
0511cc75 25063@end table
bccbefd2
JK
25064
25065On the other hand you can also explicitly forbid automatic files loading which
25066also suppresses any such warning messages:
25067
0511cc75 25068@table @asis
174bb630 25069@item @kbd{gdb -iex "set auto-load no" @dots{}}
bccbefd2
JK
25070You can use @value{GDBN} command-line option for a single @value{GDBN} session.
25071
0511cc75 25072@item @file{~/.gdbinit}: @samp{set auto-load no}
bccbefd2
JK
25073Disable auto-loading globally for the user
25074(@pxref{Home Directory Init File}). While it is improbable, you could also
25075use system init file instead (@pxref{System-wide configuration}).
0511cc75 25076@end table
bccbefd2
JK
25077
25078This setting applies to the file names as entered by user. If no entry matches
25079@value{GDBN} tries as a last resort to also resolve all the file names into
25080their canonical form (typically resolving symbolic links) and compare the
25081entries again. @value{GDBN} already canonicalizes most of the filenames on its
25082own before starting the comparison so a canonical form of directories is
25083recommended to be entered.
25084
4dc84fd1
JK
25085@node Auto-loading verbose mode
25086@subsection Displaying files tried for auto-load
25087@cindex auto-loading verbose mode
25088
25089For better visibility of all the file locations where you can place scripts to
25090be auto-loaded with inferior --- or to protect yourself against accidental
25091execution of untrusted scripts --- @value{GDBN} provides a feature for printing
25092all the files attempted to be loaded. Both existing and non-existing files may
25093be printed.
25094
25095For example the list of directories from which it is safe to auto-load files
25096(@pxref{Auto-loading safe path}) applies also to canonicalized filenames which
25097may not be too obvious while setting it up.
25098
25099@smallexample
0070f25a 25100(gdb) set debug auto-load on
4dc84fd1
JK
25101(gdb) file ~/src/t/true
25102auto-load: Loading canned sequences of commands script "/tmp/true-gdb.gdb"
25103 for objfile "/tmp/true".
25104auto-load: Updating directories of "/usr:/opt".
25105auto-load: Using directory "/usr".
25106auto-load: Using directory "/opt".
25107warning: File "/tmp/true-gdb.gdb" auto-loading has been declined
25108 by your `auto-load safe-path' set to "/usr:/opt".
25109@end smallexample
25110
25111@table @code
25112@anchor{set debug auto-load}
25113@kindex set debug auto-load
25114@item set debug auto-load [on|off]
25115Set whether to print the filenames attempted to be auto-loaded.
25116
25117@anchor{show debug auto-load}
25118@kindex show debug auto-load
25119@item show debug auto-load
25120Show whether printing of the filenames attempted to be auto-loaded is turned
25121on or off.
25122@end table
25123
8e04817f 25124@node Messages/Warnings
79a6e687 25125@section Optional Warnings and Messages
104c1213 25126
9c16f35a
EZ
25127@cindex verbose operation
25128@cindex optional warnings
8e04817f
AC
25129By default, @value{GDBN} is silent about its inner workings. If you are
25130running on a slow machine, you may want to use the @code{set verbose}
25131command. This makes @value{GDBN} tell you when it does a lengthy
25132internal operation, so you will not think it has crashed.
104c1213 25133
8e04817f
AC
25134Currently, the messages controlled by @code{set verbose} are those
25135which announce that the symbol table for a source file is being read;
79a6e687 25136see @code{symbol-file} in @ref{Files, ,Commands to Specify Files}.
104c1213 25137
8e04817f
AC
25138@table @code
25139@kindex set verbose
25140@item set verbose on
25141Enables @value{GDBN} output of certain informational messages.
104c1213 25142
8e04817f
AC
25143@item set verbose off
25144Disables @value{GDBN} output of certain informational messages.
104c1213 25145
8e04817f
AC
25146@kindex show verbose
25147@item show verbose
25148Displays whether @code{set verbose} is on or off.
25149@end table
104c1213 25150
8e04817f
AC
25151By default, if @value{GDBN} encounters bugs in the symbol table of an
25152object file, it is silent; but if you are debugging a compiler, you may
79a6e687
BW
25153find this information useful (@pxref{Symbol Errors, ,Errors Reading
25154Symbol Files}).
104c1213 25155
8e04817f 25156@table @code
104c1213 25157
8e04817f
AC
25158@kindex set complaints
25159@item set complaints @var{limit}
25160Permits @value{GDBN} to output @var{limit} complaints about each type of
25161unusual symbols before becoming silent about the problem. Set
25162@var{limit} to zero to suppress all complaints; set it to a large number
25163to prevent complaints from being suppressed.
104c1213 25164
8e04817f
AC
25165@kindex show complaints
25166@item show complaints
25167Displays how many symbol complaints @value{GDBN} is permitted to produce.
104c1213 25168
8e04817f 25169@end table
104c1213 25170
d837706a 25171@anchor{confirmation requests}
8e04817f
AC
25172By default, @value{GDBN} is cautious, and asks what sometimes seems to be a
25173lot of stupid questions to confirm certain commands. For example, if
25174you try to run a program which is already running:
104c1213 25175
474c8240 25176@smallexample
8e04817f
AC
25177(@value{GDBP}) run
25178The program being debugged has been started already.
25179Start it from the beginning? (y or n)
474c8240 25180@end smallexample
104c1213 25181
8e04817f
AC
25182If you are willing to unflinchingly face the consequences of your own
25183commands, you can disable this ``feature'':
104c1213 25184
8e04817f 25185@table @code
104c1213 25186
8e04817f
AC
25187@kindex set confirm
25188@cindex flinching
25189@cindex confirmation
25190@cindex stupid questions
25191@item set confirm off
7c953934
TT
25192Disables confirmation requests. Note that running @value{GDBN} with
25193the @option{--batch} option (@pxref{Mode Options, -batch}) also
25194automatically disables confirmation requests.
104c1213 25195
8e04817f
AC
25196@item set confirm on
25197Enables confirmation requests (the default).
104c1213 25198
8e04817f
AC
25199@kindex show confirm
25200@item show confirm
25201Displays state of confirmation requests.
25202
25203@end table
104c1213 25204
16026cd7
AS
25205@cindex command tracing
25206If you need to debug user-defined commands or sourced files you may find it
25207useful to enable @dfn{command tracing}. In this mode each command will be
25208printed as it is executed, prefixed with one or more @samp{+} symbols, the
25209quantity denoting the call depth of each command.
25210
25211@table @code
25212@kindex set trace-commands
25213@cindex command scripts, debugging
25214@item set trace-commands on
25215Enable command tracing.
25216@item set trace-commands off
25217Disable command tracing.
25218@item show trace-commands
25219Display the current state of command tracing.
25220@end table
25221
8e04817f 25222@node Debugging Output
79a6e687 25223@section Optional Messages about Internal Happenings
4644b6e3
EZ
25224@cindex optional debugging messages
25225
da316a69
EZ
25226@value{GDBN} has commands that enable optional debugging messages from
25227various @value{GDBN} subsystems; normally these commands are of
25228interest to @value{GDBN} maintainers, or when reporting a bug. This
25229section documents those commands.
25230
104c1213 25231@table @code
a8f24a35
EZ
25232@kindex set exec-done-display
25233@item set exec-done-display
25234Turns on or off the notification of asynchronous commands'
25235completion. When on, @value{GDBN} will print a message when an
25236asynchronous command finishes its execution. The default is off.
25237@kindex show exec-done-display
25238@item show exec-done-display
25239Displays the current setting of asynchronous command completion
25240notification.
4644b6e3 25241@kindex set debug
be9a8770
PA
25242@cindex ARM AArch64
25243@item set debug aarch64
25244Turns on or off display of debugging messages related to ARM AArch64.
25245The default is off.
25246@kindex show debug
25247@item show debug aarch64
25248Displays the current state of displaying debugging messages related to
25249ARM AArch64.
4644b6e3 25250@cindex gdbarch debugging info
a8f24a35 25251@cindex architecture debugging info
8e04817f 25252@item set debug arch
a8f24a35 25253Turns on or off display of gdbarch debugging info. The default is off
8e04817f
AC
25254@item show debug arch
25255Displays the current state of displaying gdbarch debugging info.
9a005eb9
JB
25256@item set debug aix-solib
25257@cindex AIX shared library debugging
25258Control display of debugging messages from the AIX shared library
25259support module. The default is off.
25260@item show debug aix-thread
25261Show the current state of displaying AIX shared library debugging messages.
721c2651
EZ
25262@item set debug aix-thread
25263@cindex AIX threads
25264Display debugging messages about inner workings of the AIX thread
25265module.
25266@item show debug aix-thread
25267Show the current state of AIX thread debugging info display.
900e11f9
JK
25268@item set debug check-physname
25269@cindex physname
25270Check the results of the ``physname'' computation. When reading DWARF
25271debugging information for C@t{++}, @value{GDBN} attempts to compute
25272each entity's name. @value{GDBN} can do this computation in two
25273different ways, depending on exactly what information is present.
25274When enabled, this setting causes @value{GDBN} to compute the names
25275both ways and display any discrepancies.
25276@item show debug check-physname
25277Show the current state of ``physname'' checking.
be9a8770
PA
25278@item set debug coff-pe-read
25279@cindex COFF/PE exported symbols
25280Control display of debugging messages related to reading of COFF/PE
25281exported symbols. The default is off.
25282@item show debug coff-pe-read
25283Displays the current state of displaying debugging messages related to
25284reading of COFF/PE exported symbols.
b4f54984
DE
25285@item set debug dwarf-die
25286@cindex DWARF DIEs
25287Dump DWARF DIEs after they are read in.
d97bc12b
DE
25288The value is the number of nesting levels to print.
25289A value of zero turns off the display.
b4f54984
DE
25290@item show debug dwarf-die
25291Show the current state of DWARF DIE debugging.
27e0867f
DE
25292@item set debug dwarf-line
25293@cindex DWARF Line Tables
25294Turns on or off display of debugging messages related to reading
25295DWARF line tables. The default is 0 (off).
25296A value of 1 provides basic information.
25297A value greater than 1 provides more verbose information.
25298@item show debug dwarf-line
25299Show the current state of DWARF line table debugging.
b4f54984
DE
25300@item set debug dwarf-read
25301@cindex DWARF Reading
45cfd468 25302Turns on or off display of debugging messages related to reading
73be47f5
DE
25303DWARF debug info. The default is 0 (off).
25304A value of 1 provides basic information.
25305A value greater than 1 provides more verbose information.
b4f54984
DE
25306@item show debug dwarf-read
25307Show the current state of DWARF reader debugging.
237fc4c9
PA
25308@item set debug displaced
25309@cindex displaced stepping debugging info
25310Turns on or off display of @value{GDBN} debugging info for the
25311displaced stepping support. The default is off.
25312@item show debug displaced
25313Displays the current state of displaying @value{GDBN} debugging info
25314related to displaced stepping.
8e04817f 25315@item set debug event
4644b6e3 25316@cindex event debugging info
a8f24a35 25317Turns on or off display of @value{GDBN} event debugging info. The
8e04817f 25318default is off.
8e04817f
AC
25319@item show debug event
25320Displays the current state of displaying @value{GDBN} event debugging
25321info.
8e04817f 25322@item set debug expression
4644b6e3 25323@cindex expression debugging info
721c2651
EZ
25324Turns on or off display of debugging info about @value{GDBN}
25325expression parsing. The default is off.
8e04817f 25326@item show debug expression
721c2651
EZ
25327Displays the current state of displaying debugging info about
25328@value{GDBN} expression parsing.
6e9567fe
JB
25329@item set debug fbsd-lwp
25330@cindex FreeBSD LWP debug messages
25331Turns on or off debugging messages from the FreeBSD LWP debug support.
25332@item show debug fbsd-lwp
25333Show the current state of FreeBSD LWP debugging messages.
386a8676
JB
25334@item set debug fbsd-nat
25335@cindex FreeBSD native target debug messages
25336Turns on or off debugging messages from the FreeBSD native target.
25337@item show debug fbsd-nat
25338Show the current state of FreeBSD native target debugging messages.
7453dc06 25339@item set debug frame
4644b6e3 25340@cindex frame debugging info
7453dc06
AC
25341Turns on or off display of @value{GDBN} frame debugging info. The
25342default is off.
7453dc06
AC
25343@item show debug frame
25344Displays the current state of displaying @value{GDBN} frame debugging
25345info.
cbe54154
PA
25346@item set debug gnu-nat
25347@cindex @sc{gnu}/Hurd debug messages
67ebd9cb 25348Turn on or off debugging messages from the @sc{gnu}/Hurd debug support.
cbe54154
PA
25349@item show debug gnu-nat
25350Show the current state of @sc{gnu}/Hurd debugging messages.
30e91e0b
RC
25351@item set debug infrun
25352@cindex inferior debugging info
25353Turns on or off display of @value{GDBN} debugging info for running the inferior.
25354The default is off. @file{infrun.c} contains GDB's runtime state machine used
25355for implementing operations such as single-stepping the inferior.
25356@item show debug infrun
25357Displays the current state of @value{GDBN} inferior debugging.
a255712f
PP
25358@item set debug jit
25359@cindex just-in-time compilation, debugging messages
67ebd9cb 25360Turn on or off debugging messages from JIT debug support.
a255712f
PP
25361@item show debug jit
25362Displays the current state of @value{GDBN} JIT debugging.
da316a69
EZ
25363@item set debug lin-lwp
25364@cindex @sc{gnu}/Linux LWP debug messages
25365@cindex Linux lightweight processes
67ebd9cb 25366Turn on or off debugging messages from the Linux LWP debug support.
da316a69
EZ
25367@item show debug lin-lwp
25368Show the current state of Linux LWP debugging messages.
7a6a1731
GB
25369@item set debug linux-namespaces
25370@cindex @sc{gnu}/Linux namespaces debug messages
67ebd9cb 25371Turn on or off debugging messages from the Linux namespaces debug support.
7a6a1731
GB
25372@item show debug linux-namespaces
25373Show the current state of Linux namespaces debugging messages.
be9a8770
PA
25374@item set debug mach-o
25375@cindex Mach-O symbols processing
25376Control display of debugging messages related to Mach-O symbols
25377processing. The default is off.
25378@item show debug mach-o
25379Displays the current state of displaying debugging messages related to
25380reading of COFF/PE exported symbols.
c9b6281a
YQ
25381@item set debug notification
25382@cindex remote async notification debugging info
67ebd9cb 25383Turn on or off debugging messages about remote async notification.
c9b6281a
YQ
25384The default is off.
25385@item show debug notification
25386Displays the current state of remote async notification debugging messages.
2b4855ab 25387@item set debug observer
4644b6e3 25388@cindex observer debugging info
2b4855ab
AC
25389Turns on or off display of @value{GDBN} observer debugging. This
25390includes info such as the notification of observable events.
2b4855ab
AC
25391@item show debug observer
25392Displays the current state of observer debugging.
8e04817f 25393@item set debug overload
4644b6e3 25394@cindex C@t{++} overload debugging info
8e04817f 25395Turns on or off display of @value{GDBN} C@t{++} overload debugging
359df76b 25396info. This includes info such as ranking of functions, etc. The default
8e04817f 25397is off.
8e04817f
AC
25398@item show debug overload
25399Displays the current state of displaying @value{GDBN} C@t{++} overload
25400debugging info.
92981e24
TT
25401@cindex expression parser, debugging info
25402@cindex debug expression parser
25403@item set debug parser
25404Turns on or off the display of expression parser debugging output.
25405Internally, this sets the @code{yydebug} variable in the expression
25406parser. @xref{Tracing, , Tracing Your Parser, bison, Bison}, for
25407details. The default is off.
25408@item show debug parser
25409Show the current state of expression parser debugging.
8e04817f
AC
25410@cindex packets, reporting on stdout
25411@cindex serial connections, debugging
605a56cb
DJ
25412@cindex debug remote protocol
25413@cindex remote protocol debugging
25414@cindex display remote packets
8e04817f
AC
25415@item set debug remote
25416Turns on or off display of reports on all packets sent back and forth across
25417the serial line to the remote machine. The info is printed on the
25418@value{GDBN} standard output stream. The default is off.
8e04817f
AC
25419@item show debug remote
25420Displays the state of display of remote packets.
c4dcb155
SM
25421
25422@item set debug separate-debug-file
25423Turns on or off display of debug output about separate debug file search.
25424@item show debug separate-debug-file
25425Displays the state of separate debug file search debug output.
25426
8e04817f
AC
25427@item set debug serial
25428Turns on or off display of @value{GDBN} serial debugging info. The
25429default is off.
8e04817f
AC
25430@item show debug serial
25431Displays the current state of displaying @value{GDBN} serial debugging
25432info.
c45da7e6
EZ
25433@item set debug solib-frv
25434@cindex FR-V shared-library debugging
67ebd9cb 25435Turn on or off debugging messages for FR-V shared-library code.
c45da7e6
EZ
25436@item show debug solib-frv
25437Display the current state of FR-V shared-library code debugging
25438messages.
cc485e62
DE
25439@item set debug symbol-lookup
25440@cindex symbol lookup
25441Turns on or off display of debugging messages related to symbol lookup.
25442The default is 0 (off).
25443A value of 1 provides basic information.
25444A value greater than 1 provides more verbose information.
25445@item show debug symbol-lookup
25446Show the current state of symbol lookup debugging messages.
8fb8eb5c
DE
25447@item set debug symfile
25448@cindex symbol file functions
25449Turns on or off display of debugging messages related to symbol file functions.
25450The default is off. @xref{Files}.
25451@item show debug symfile
25452Show the current state of symbol file debugging messages.
45cfd468
DE
25453@item set debug symtab-create
25454@cindex symbol table creation
25455Turns on or off display of debugging messages related to symbol table creation.
db0fec5c
DE
25456The default is 0 (off).
25457A value of 1 provides basic information.
25458A value greater than 1 provides more verbose information.
45cfd468
DE
25459@item show debug symtab-create
25460Show the current state of symbol table creation debugging.
8e04817f 25461@item set debug target
4644b6e3 25462@cindex target debugging info
8e04817f
AC
25463Turns on or off display of @value{GDBN} target debugging info. This info
25464includes what is going on at the target level of GDB, as it happens. The
701b08bb 25465default is 0. Set it to 1 to track events, and to 2 to also track the
3cecbbbe 25466value of large memory transfers.
8e04817f
AC
25467@item show debug target
25468Displays the current state of displaying @value{GDBN} target debugging
25469info.
75feb17d
DJ
25470@item set debug timestamp
25471@cindex timestampping debugging info
25472Turns on or off display of timestamps with @value{GDBN} debugging info.
25473When enabled, seconds and microseconds are displayed before each debugging
25474message.
25475@item show debug timestamp
25476Displays the current state of displaying timestamps with @value{GDBN}
25477debugging info.
f989a1c8 25478@item set debug varobj
4644b6e3 25479@cindex variable object debugging info
8e04817f
AC
25480Turns on or off display of @value{GDBN} variable object debugging
25481info. The default is off.
f989a1c8 25482@item show debug varobj
8e04817f
AC
25483Displays the current state of displaying @value{GDBN} variable object
25484debugging info.
e776119f
DJ
25485@item set debug xml
25486@cindex XML parser debugging
67ebd9cb 25487Turn on or off debugging messages for built-in XML parsers.
e776119f
DJ
25488@item show debug xml
25489Displays the current state of XML debugging messages.
8e04817f 25490@end table
104c1213 25491
14fb1bac
JB
25492@node Other Misc Settings
25493@section Other Miscellaneous Settings
25494@cindex miscellaneous settings
25495
25496@table @code
25497@kindex set interactive-mode
25498@item set interactive-mode
7bfc9434
JB
25499If @code{on}, forces @value{GDBN} to assume that GDB was started
25500in a terminal. In practice, this means that @value{GDBN} should wait
25501for the user to answer queries generated by commands entered at
25502the command prompt. If @code{off}, forces @value{GDBN} to operate
25503in the opposite mode, and it uses the default answers to all queries.
25504If @code{auto} (the default), @value{GDBN} tries to determine whether
25505its standard input is a terminal, and works in interactive-mode if it
25506is, non-interactively otherwise.
14fb1bac
JB
25507
25508In the vast majority of cases, the debugger should be able to guess
25509correctly which mode should be used. But this setting can be useful
25510in certain specific cases, such as running a MinGW @value{GDBN}
25511inside a cygwin window.
25512
25513@kindex show interactive-mode
25514@item show interactive-mode
25515Displays whether the debugger is operating in interactive mode or not.
25516@end table
25517
d57a3c85
TJB
25518@node Extending GDB
25519@chapter Extending @value{GDBN}
25520@cindex extending GDB
25521
71b8c845
DE
25522@value{GDBN} provides several mechanisms for extension.
25523@value{GDBN} also provides the ability to automatically load
25524extensions when it reads a file for debugging. This allows the
25525user to automatically customize @value{GDBN} for the program
25526being debugged.
d57a3c85 25527
71b8c845
DE
25528@menu
25529* Sequences:: Canned Sequences of @value{GDBN} Commands
25530* Python:: Extending @value{GDBN} using Python
ed3ef339 25531* Guile:: Extending @value{GDBN} using Guile
71b8c845 25532* Auto-loading extensions:: Automatically loading extensions
ed3ef339 25533* Multiple Extension Languages:: Working with multiple extension languages
71b8c845
DE
25534* Aliases:: Creating new spellings of existing commands
25535@end menu
25536
25537To facilitate the use of extension languages, @value{GDBN} is capable
95433b34 25538of evaluating the contents of a file. When doing so, @value{GDBN}
71b8c845 25539can recognize which extension language is being used by looking at
95433b34
JB
25540the filename extension. Files with an unrecognized filename extension
25541are always treated as a @value{GDBN} Command Files.
25542@xref{Command Files,, Command files}.
25543
25544You can control how @value{GDBN} evaluates these files with the following
25545setting:
25546
25547@table @code
25548@kindex set script-extension
25549@kindex show script-extension
25550@item set script-extension off
25551All scripts are always evaluated as @value{GDBN} Command Files.
25552
25553@item set script-extension soft
25554The debugger determines the scripting language based on filename
25555extension. If this scripting language is supported, @value{GDBN}
25556evaluates the script using that language. Otherwise, it evaluates
25557the file as a @value{GDBN} Command File.
25558
25559@item set script-extension strict
25560The debugger determines the scripting language based on filename
25561extension, and evaluates the script using that language. If the
25562language is not supported, then the evaluation fails.
25563
25564@item show script-extension
25565Display the current value of the @code{script-extension} option.
25566
25567@end table
25568
8e04817f 25569@node Sequences
d57a3c85 25570@section Canned Sequences of Commands
104c1213 25571
8e04817f 25572Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint
79a6e687 25573Command Lists}), @value{GDBN} provides two ways to store sequences of
8e04817f
AC
25574commands for execution as a unit: user-defined commands and command
25575files.
104c1213 25576
8e04817f 25577@menu
fcc73fe3
EZ
25578* Define:: How to define your own commands
25579* Hooks:: Hooks for user-defined commands
25580* Command Files:: How to write scripts of commands to be stored in a file
25581* Output:: Commands for controlled output
71b8c845 25582* Auto-loading sequences:: Controlling auto-loaded command files
8e04817f 25583@end menu
104c1213 25584
8e04817f 25585@node Define
d57a3c85 25586@subsection User-defined Commands
104c1213 25587
8e04817f 25588@cindex user-defined command
fcc73fe3 25589@cindex arguments, to user-defined commands
8e04817f
AC
25590A @dfn{user-defined command} is a sequence of @value{GDBN} commands to
25591which you assign a new name as a command. This is done with the
df3ee9ca 25592@code{define} command. User commands may accept an unlimited number of arguments
8e04817f 25593separated by whitespace. Arguments are accessed within the user command
df3ee9ca 25594via @code{$arg0@dots{}$argN}. A trivial example:
104c1213 25595
8e04817f
AC
25596@smallexample
25597define adder
25598 print $arg0 + $arg1 + $arg2
c03c782f 25599end
8e04817f 25600@end smallexample
104c1213
JM
25601
25602@noindent
8e04817f 25603To execute the command use:
104c1213 25604
8e04817f
AC
25605@smallexample
25606adder 1 2 3
25607@end smallexample
104c1213 25608
8e04817f
AC
25609@noindent
25610This defines the command @code{adder}, which prints the sum of
25611its three arguments. Note the arguments are text substitutions, so they may
25612reference variables, use complex expressions, or even perform inferior
25613functions calls.
104c1213 25614
fcc73fe3
EZ
25615@cindex argument count in user-defined commands
25616@cindex how many arguments (user-defined commands)
c03c782f 25617In addition, @code{$argc} may be used to find out how many arguments have
df3ee9ca 25618been passed.
c03c782f
AS
25619
25620@smallexample
25621define adder
25622 if $argc == 2
25623 print $arg0 + $arg1
25624 end
25625 if $argc == 3
25626 print $arg0 + $arg1 + $arg2
25627 end
25628end
25629@end smallexample
25630
01770bbd
PA
25631Combining with the @code{eval} command (@pxref{eval}) makes it easier
25632to process a variable number of arguments:
25633
25634@smallexample
25635define adder
25636 set $i = 0
25637 set $sum = 0
25638 while $i < $argc
25639 eval "set $sum = $sum + $arg%d", $i
25640 set $i = $i + 1
25641 end
25642 print $sum
25643end
25644@end smallexample
25645
104c1213 25646@table @code
104c1213 25647
8e04817f
AC
25648@kindex define
25649@item define @var{commandname}
25650Define a command named @var{commandname}. If there is already a command
25651by that name, you are asked to confirm that you want to redefine it.
697aa1b7 25652The argument @var{commandname} may be a bare command name consisting of letters,
adb483fe
DJ
25653numbers, dashes, and underscores. It may also start with any predefined
25654prefix command. For example, @samp{define target my-target} creates
25655a user-defined @samp{target my-target} command.
104c1213 25656
8e04817f
AC
25657The definition of the command is made up of other @value{GDBN} command lines,
25658which are given following the @code{define} command. The end of these
25659commands is marked by a line containing @code{end}.
104c1213 25660
8e04817f 25661@kindex document
ca91424e 25662@kindex end@r{ (user-defined commands)}
8e04817f
AC
25663@item document @var{commandname}
25664Document the user-defined command @var{commandname}, so that it can be
25665accessed by @code{help}. The command @var{commandname} must already be
25666defined. This command reads lines of documentation just as @code{define}
25667reads the lines of the command definition, ending with @code{end}.
25668After the @code{document} command is finished, @code{help} on command
25669@var{commandname} displays the documentation you have written.
104c1213 25670
8e04817f
AC
25671You may use the @code{document} command again to change the
25672documentation of a command. Redefining the command with @code{define}
25673does not change the documentation.
104c1213 25674
c45da7e6
EZ
25675@kindex dont-repeat
25676@cindex don't repeat command
25677@item dont-repeat
25678Used inside a user-defined command, this tells @value{GDBN} that this
25679command should not be repeated when the user hits @key{RET}
25680(@pxref{Command Syntax, repeat last command}).
25681
8e04817f
AC
25682@kindex help user-defined
25683@item help user-defined
7d74f244
DE
25684List all user-defined commands and all python commands defined in class
25685COMAND_USER. The first line of the documentation or docstring is
25686included (if any).
104c1213 25687
8e04817f
AC
25688@kindex show user
25689@item show user
25690@itemx show user @var{commandname}
25691Display the @value{GDBN} commands used to define @var{commandname} (but
25692not its documentation). If no @var{commandname} is given, display the
25693definitions for all user-defined commands.
7d74f244 25694This does not work for user-defined python commands.
104c1213 25695
fcc73fe3 25696@cindex infinite recursion in user-defined commands
20f01a46
DH
25697@kindex show max-user-call-depth
25698@kindex set max-user-call-depth
25699@item show max-user-call-depth
5ca0cb28
DH
25700@itemx set max-user-call-depth
25701The value of @code{max-user-call-depth} controls how many recursion
3f94c067 25702levels are allowed in user-defined commands before @value{GDBN} suspects an
5ca0cb28 25703infinite recursion and aborts the command.
7d74f244 25704This does not apply to user-defined python commands.
104c1213
JM
25705@end table
25706
fcc73fe3
EZ
25707In addition to the above commands, user-defined commands frequently
25708use control flow commands, described in @ref{Command Files}.
25709
8e04817f
AC
25710When user-defined commands are executed, the
25711commands of the definition are not printed. An error in any command
25712stops execution of the user-defined command.
104c1213 25713
8e04817f
AC
25714If used interactively, commands that would ask for confirmation proceed
25715without asking when used inside a user-defined command. Many @value{GDBN}
25716commands that normally print messages to say what they are doing omit the
25717messages when used in a user-defined command.
104c1213 25718
8e04817f 25719@node Hooks
d57a3c85 25720@subsection User-defined Command Hooks
8e04817f
AC
25721@cindex command hooks
25722@cindex hooks, for commands
25723@cindex hooks, pre-command
104c1213 25724
8e04817f 25725@kindex hook
8e04817f
AC
25726You may define @dfn{hooks}, which are a special kind of user-defined
25727command. Whenever you run the command @samp{foo}, if the user-defined
25728command @samp{hook-foo} exists, it is executed (with no arguments)
25729before that command.
104c1213 25730
8e04817f
AC
25731@cindex hooks, post-command
25732@kindex hookpost
8e04817f
AC
25733A hook may also be defined which is run after the command you executed.
25734Whenever you run the command @samp{foo}, if the user-defined command
25735@samp{hookpost-foo} exists, it is executed (with no arguments) after
25736that command. Post-execution hooks may exist simultaneously with
25737pre-execution hooks, for the same command.
104c1213 25738
8e04817f 25739It is valid for a hook to call the command which it hooks. If this
9f1c6395 25740occurs, the hook is not re-executed, thereby avoiding infinite recursion.
104c1213 25741
8e04817f
AC
25742@c It would be nice if hookpost could be passed a parameter indicating
25743@c if the command it hooks executed properly or not. FIXME!
104c1213 25744
8e04817f
AC
25745@kindex stop@r{, a pseudo-command}
25746In addition, a pseudo-command, @samp{stop} exists. Defining
25747(@samp{hook-stop}) makes the associated commands execute every time
25748execution stops in your program: before breakpoint commands are run,
25749displays are printed, or the stack frame is printed.
104c1213 25750
8e04817f
AC
25751For example, to ignore @code{SIGALRM} signals while
25752single-stepping, but treat them normally during normal execution,
25753you could define:
104c1213 25754
474c8240 25755@smallexample
8e04817f
AC
25756define hook-stop
25757handle SIGALRM nopass
25758end
104c1213 25759
8e04817f
AC
25760define hook-run
25761handle SIGALRM pass
25762end
104c1213 25763
8e04817f 25764define hook-continue
d3e8051b 25765handle SIGALRM pass
8e04817f 25766end
474c8240 25767@end smallexample
104c1213 25768
d3e8051b 25769As a further example, to hook at the beginning and end of the @code{echo}
b383017d 25770command, and to add extra text to the beginning and end of the message,
8e04817f 25771you could define:
104c1213 25772
474c8240 25773@smallexample
8e04817f
AC
25774define hook-echo
25775echo <<<---
25776end
104c1213 25777
8e04817f
AC
25778define hookpost-echo
25779echo --->>>\n
25780end
104c1213 25781
8e04817f
AC
25782(@value{GDBP}) echo Hello World
25783<<<---Hello World--->>>
25784(@value{GDBP})
104c1213 25785
474c8240 25786@end smallexample
104c1213 25787
8e04817f
AC
25788You can define a hook for any single-word command in @value{GDBN}, but
25789not for command aliases; you should define a hook for the basic command
c1468174 25790name, e.g.@: @code{backtrace} rather than @code{bt}.
8e04817f
AC
25791@c FIXME! So how does Joe User discover whether a command is an alias
25792@c or not?
adb483fe
DJ
25793You can hook a multi-word command by adding @code{hook-} or
25794@code{hookpost-} to the last word of the command, e.g.@:
25795@samp{define target hook-remote} to add a hook to @samp{target remote}.
25796
8e04817f
AC
25797If an error occurs during the execution of your hook, execution of
25798@value{GDBN} commands stops and @value{GDBN} issues a prompt
25799(before the command that you actually typed had a chance to run).
104c1213 25800
8e04817f
AC
25801If you try to define a hook which does not match any known command, you
25802get a warning from the @code{define} command.
c906108c 25803
8e04817f 25804@node Command Files
d57a3c85 25805@subsection Command Files
c906108c 25806
8e04817f 25807@cindex command files
fcc73fe3 25808@cindex scripting commands
6fc08d32
EZ
25809A command file for @value{GDBN} is a text file made of lines that are
25810@value{GDBN} commands. Comments (lines starting with @kbd{#}) may
25811also be included. An empty line in a command file does nothing; it
25812does not mean to repeat the last command, as it would from the
25813terminal.
c906108c 25814
6fc08d32 25815You can request the execution of a command file with the @code{source}
95433b34
JB
25816command. Note that the @code{source} command is also used to evaluate
25817scripts that are not Command Files. The exact behavior can be configured
25818using the @code{script-extension} setting.
25819@xref{Extending GDB,, Extending GDB}.
c906108c 25820
8e04817f
AC
25821@table @code
25822@kindex source
ca91424e 25823@cindex execute commands from a file
3f7b2faa 25824@item source [-s] [-v] @var{filename}
8e04817f 25825Execute the command file @var{filename}.
c906108c
SS
25826@end table
25827
fcc73fe3
EZ
25828The lines in a command file are generally executed sequentially,
25829unless the order of execution is changed by one of the
25830@emph{flow-control commands} described below. The commands are not
a71ec265
DH
25831printed as they are executed. An error in any command terminates
25832execution of the command file and control is returned to the console.
c906108c 25833
08001717
DE
25834@value{GDBN} first searches for @var{filename} in the current directory.
25835If the file is not found there, and @var{filename} does not specify a
25836directory, then @value{GDBN} also looks for the file on the source search path
25837(specified with the @samp{directory} command);
25838except that @file{$cdir} is not searched because the compilation directory
25839is not relevant to scripts.
4b505b12 25840
3f7b2faa
DE
25841If @code{-s} is specified, then @value{GDBN} searches for @var{filename}
25842on the search path even if @var{filename} specifies a directory.
25843The search is done by appending @var{filename} to each element of the
25844search path. So, for example, if @var{filename} is @file{mylib/myscript}
25845and the search path contains @file{/home/user} then @value{GDBN} will
25846look for the script @file{/home/user/mylib/myscript}.
25847The search is also done if @var{filename} is an absolute path.
25848For example, if @var{filename} is @file{/tmp/myscript} and
25849the search path contains @file{/home/user} then @value{GDBN} will
25850look for the script @file{/home/user/tmp/myscript}.
25851For DOS-like systems, if @var{filename} contains a drive specification,
25852it is stripped before concatenation. For example, if @var{filename} is
25853@file{d:myscript} and the search path contains @file{c:/tmp} then @value{GDBN}
25854will look for the script @file{c:/tmp/myscript}.
25855
16026cd7
AS
25856If @code{-v}, for verbose mode, is given then @value{GDBN} displays
25857each command as it is executed. The option must be given before
25858@var{filename}, and is interpreted as part of the filename anywhere else.
25859
8e04817f
AC
25860Commands that would ask for confirmation if used interactively proceed
25861without asking when used in a command file. Many @value{GDBN} commands that
25862normally print messages to say what they are doing omit the messages
25863when called from command files.
c906108c 25864
8e04817f
AC
25865@value{GDBN} also accepts command input from standard input. In this
25866mode, normal output goes to standard output and error output goes to
25867standard error. Errors in a command file supplied on standard input do
6fc08d32 25868not terminate execution of the command file---execution continues with
8e04817f 25869the next command.
c906108c 25870
474c8240 25871@smallexample
8e04817f 25872gdb < cmds > log 2>&1
474c8240 25873@end smallexample
c906108c 25874
8e04817f
AC
25875(The syntax above will vary depending on the shell used.) This example
25876will execute commands from the file @file{cmds}. All output and errors
25877would be directed to @file{log}.
c906108c 25878
fcc73fe3
EZ
25879Since commands stored on command files tend to be more general than
25880commands typed interactively, they frequently need to deal with
25881complicated situations, such as different or unexpected values of
25882variables and symbols, changes in how the program being debugged is
25883built, etc. @value{GDBN} provides a set of flow-control commands to
25884deal with these complexities. Using these commands, you can write
25885complex scripts that loop over data structures, execute commands
25886conditionally, etc.
25887
25888@table @code
25889@kindex if
25890@kindex else
25891@item if
25892@itemx else
25893This command allows to include in your script conditionally executed
25894commands. The @code{if} command takes a single argument, which is an
25895expression to evaluate. It is followed by a series of commands that
25896are executed only if the expression is true (its value is nonzero).
25897There can then optionally be an @code{else} line, followed by a series
25898of commands that are only executed if the expression was false. The
25899end of the list is marked by a line containing @code{end}.
25900
25901@kindex while
25902@item while
25903This command allows to write loops. Its syntax is similar to
25904@code{if}: the command takes a single argument, which is an expression
25905to evaluate, and must be followed by the commands to execute, one per
25906line, terminated by an @code{end}. These commands are called the
25907@dfn{body} of the loop. The commands in the body of @code{while} are
25908executed repeatedly as long as the expression evaluates to true.
25909
25910@kindex loop_break
25911@item loop_break
25912This command exits the @code{while} loop in whose body it is included.
25913Execution of the script continues after that @code{while}s @code{end}
25914line.
25915
25916@kindex loop_continue
25917@item loop_continue
25918This command skips the execution of the rest of the body of commands
25919in the @code{while} loop in whose body it is included. Execution
25920branches to the beginning of the @code{while} loop, where it evaluates
25921the controlling expression.
ca91424e
EZ
25922
25923@kindex end@r{ (if/else/while commands)}
25924@item end
25925Terminate the block of commands that are the body of @code{if},
25926@code{else}, or @code{while} flow-control commands.
fcc73fe3
EZ
25927@end table
25928
25929
8e04817f 25930@node Output
d57a3c85 25931@subsection Commands for Controlled Output
c906108c 25932
8e04817f
AC
25933During the execution of a command file or a user-defined command, normal
25934@value{GDBN} output is suppressed; the only output that appears is what is
25935explicitly printed by the commands in the definition. This section
25936describes three commands useful for generating exactly the output you
25937want.
c906108c
SS
25938
25939@table @code
8e04817f
AC
25940@kindex echo
25941@item echo @var{text}
25942@c I do not consider backslash-space a standard C escape sequence
25943@c because it is not in ANSI.
25944Print @var{text}. Nonprinting characters can be included in
25945@var{text} using C escape sequences, such as @samp{\n} to print a
25946newline. @strong{No newline is printed unless you specify one.}
25947In addition to the standard C escape sequences, a backslash followed
25948by a space stands for a space. This is useful for displaying a
25949string with spaces at the beginning or the end, since leading and
25950trailing spaces are otherwise trimmed from all arguments.
25951To print @samp{@w{ }and foo =@w{ }}, use the command
25952@samp{echo \@w{ }and foo = \@w{ }}.
c906108c 25953
8e04817f
AC
25954A backslash at the end of @var{text} can be used, as in C, to continue
25955the command onto subsequent lines. For example,
c906108c 25956
474c8240 25957@smallexample
8e04817f
AC
25958echo This is some text\n\
25959which is continued\n\
25960onto several lines.\n
474c8240 25961@end smallexample
c906108c 25962
8e04817f 25963produces the same output as
c906108c 25964
474c8240 25965@smallexample
8e04817f
AC
25966echo This is some text\n
25967echo which is continued\n
25968echo onto several lines.\n
474c8240 25969@end smallexample
c906108c 25970
8e04817f
AC
25971@kindex output
25972@item output @var{expression}
25973Print the value of @var{expression} and nothing but that value: no
25974newlines, no @samp{$@var{nn} = }. The value is not entered in the
25975value history either. @xref{Expressions, ,Expressions}, for more information
25976on expressions.
c906108c 25977
8e04817f
AC
25978@item output/@var{fmt} @var{expression}
25979Print the value of @var{expression} in format @var{fmt}. You can use
25980the same formats as for @code{print}. @xref{Output Formats,,Output
79a6e687 25981Formats}, for more information.
c906108c 25982
8e04817f 25983@kindex printf
82160952
EZ
25984@item printf @var{template}, @var{expressions}@dots{}
25985Print the values of one or more @var{expressions} under the control of
25986the string @var{template}. To print several values, make
25987@var{expressions} be a comma-separated list of individual expressions,
25988which may be either numbers or pointers. Their values are printed as
25989specified by @var{template}, exactly as a C program would do by
25990executing the code below:
c906108c 25991
474c8240 25992@smallexample
82160952 25993printf (@var{template}, @var{expressions}@dots{});
474c8240 25994@end smallexample
c906108c 25995
82160952
EZ
25996As in @code{C} @code{printf}, ordinary characters in @var{template}
25997are printed verbatim, while @dfn{conversion specification} introduced
25998by the @samp{%} character cause subsequent @var{expressions} to be
25999evaluated, their values converted and formatted according to type and
26000style information encoded in the conversion specifications, and then
26001printed.
26002
8e04817f 26003For example, you can print two values in hex like this:
c906108c 26004
8e04817f
AC
26005@smallexample
26006printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
26007@end smallexample
c906108c 26008
82160952
EZ
26009@code{printf} supports all the standard @code{C} conversion
26010specifications, including the flags and modifiers between the @samp{%}
26011character and the conversion letter, with the following exceptions:
26012
26013@itemize @bullet
26014@item
26015The argument-ordering modifiers, such as @samp{2$}, are not supported.
26016
26017@item
26018The modifier @samp{*} is not supported for specifying precision or
26019width.
26020
26021@item
26022The @samp{'} flag (for separation of digits into groups according to
26023@code{LC_NUMERIC'}) is not supported.
26024
26025@item
26026The type modifiers @samp{hh}, @samp{j}, @samp{t}, and @samp{z} are not
26027supported.
26028
26029@item
26030The conversion letter @samp{n} (as in @samp{%n}) is not supported.
26031
26032@item
26033The conversion letters @samp{a} and @samp{A} are not supported.
26034@end itemize
26035
26036@noindent
26037Note that the @samp{ll} type modifier is supported only if the
26038underlying @code{C} implementation used to build @value{GDBN} supports
26039the @code{long long int} type, and the @samp{L} type modifier is
26040supported only if @code{long double} type is available.
26041
26042As in @code{C}, @code{printf} supports simple backslash-escape
26043sequences, such as @code{\n}, @samp{\t}, @samp{\\}, @samp{\"},
26044@samp{\a}, and @samp{\f}, that consist of backslash followed by a
26045single character. Octal and hexadecimal escape sequences are not
26046supported.
1a619819
LM
26047
26048Additionally, @code{printf} supports conversion specifications for DFP
0aea4bf3
LM
26049(@dfn{Decimal Floating Point}) types using the following length modifiers
26050together with a floating point specifier.
1a619819
LM
26051letters:
26052
26053@itemize @bullet
26054@item
26055@samp{H} for printing @code{Decimal32} types.
26056
26057@item
26058@samp{D} for printing @code{Decimal64} types.
26059
26060@item
26061@samp{DD} for printing @code{Decimal128} types.
26062@end itemize
26063
26064If the underlying @code{C} implementation used to build @value{GDBN} has
0aea4bf3 26065support for the three length modifiers for DFP types, other modifiers
3b784c4f 26066such as width and precision will also be available for @value{GDBN} to use.
1a619819
LM
26067
26068In case there is no such @code{C} support, no additional modifiers will be
26069available and the value will be printed in the standard way.
26070
26071Here's an example of printing DFP types using the above conversion letters:
26072@smallexample
0aea4bf3 26073printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
1a619819
LM
26074@end smallexample
26075
01770bbd 26076@anchor{eval}
f1421989
HZ
26077@kindex eval
26078@item eval @var{template}, @var{expressions}@dots{}
26079Convert the values of one or more @var{expressions} under the control of
26080the string @var{template} to a command line, and call it.
26081
c906108c
SS
26082@end table
26083
71b8c845
DE
26084@node Auto-loading sequences
26085@subsection Controlling auto-loading native @value{GDBN} scripts
26086@cindex native script auto-loading
26087
26088When a new object file is read (for example, due to the @code{file}
26089command, or because the inferior has loaded a shared library),
26090@value{GDBN} will look for the command file @file{@var{objfile}-gdb.gdb}.
26091@xref{Auto-loading extensions}.
26092
26093Auto-loading can be enabled or disabled,
26094and the list of auto-loaded scripts can be printed.
26095
26096@table @code
26097@anchor{set auto-load gdb-scripts}
26098@kindex set auto-load gdb-scripts
26099@item set auto-load gdb-scripts [on|off]
26100Enable or disable the auto-loading of canned sequences of commands scripts.
26101
26102@anchor{show auto-load gdb-scripts}
26103@kindex show auto-load gdb-scripts
26104@item show auto-load gdb-scripts
26105Show whether auto-loading of canned sequences of commands scripts is enabled or
26106disabled.
26107
26108@anchor{info auto-load gdb-scripts}
26109@kindex info auto-load gdb-scripts
26110@cindex print list of auto-loaded canned sequences of commands scripts
26111@item info auto-load gdb-scripts [@var{regexp}]
26112Print the list of all canned sequences of commands scripts that @value{GDBN}
26113auto-loaded.
26114@end table
26115
26116If @var{regexp} is supplied only canned sequences of commands scripts with
26117matching names are printed.
26118
329baa95
DE
26119@c Python docs live in a separate file.
26120@include python.texi
0e3509db 26121
ed3ef339
DE
26122@c Guile docs live in a separate file.
26123@include guile.texi
26124
71b8c845
DE
26125@node Auto-loading extensions
26126@section Auto-loading extensions
26127@cindex auto-loading extensions
26128
26129@value{GDBN} provides two mechanisms for automatically loading extensions
26130when a new object file is read (for example, due to the @code{file}
26131command, or because the inferior has loaded a shared library):
26132@file{@var{objfile}-gdb.@var{ext}} and the @code{.debug_gdb_scripts}
26133section of modern file formats like ELF.
26134
26135@menu
26136* objfile-gdb.ext file: objfile-gdbdotext file. The @file{@var{objfile}-gdb.@var{ext}} file
26137* .debug_gdb_scripts section: dotdebug_gdb_scripts section. The @code{.debug_gdb_scripts} section
26138* Which flavor to choose?::
26139@end menu
26140
26141The auto-loading feature is useful for supplying application-specific
26142debugging commands and features.
26143
26144Auto-loading can be enabled or disabled,
26145and the list of auto-loaded scripts can be printed.
26146See the @samp{auto-loading} section of each extension language
26147for more information.
26148For @value{GDBN} command files see @ref{Auto-loading sequences}.
26149For Python files see @ref{Python Auto-loading}.
26150
26151Note that loading of this script file also requires accordingly configured
26152@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
26153
26154@node objfile-gdbdotext file
26155@subsection The @file{@var{objfile}-gdb.@var{ext}} file
26156@cindex @file{@var{objfile}-gdb.gdb}
26157@cindex @file{@var{objfile}-gdb.py}
26158@cindex @file{@var{objfile}-gdb.scm}
26159
26160When a new object file is read, @value{GDBN} looks for a file named
26161@file{@var{objfile}-gdb.@var{ext}} (we call it @var{script-name} below),
26162where @var{objfile} is the object file's name and
26163where @var{ext} is the file extension for the extension language:
26164
26165@table @code
26166@item @file{@var{objfile}-gdb.gdb}
26167GDB's own command language
26168@item @file{@var{objfile}-gdb.py}
26169Python
ed3ef339
DE
26170@item @file{@var{objfile}-gdb.scm}
26171Guile
71b8c845
DE
26172@end table
26173
26174@var{script-name} is formed by ensuring that the file name of @var{objfile}
26175is absolute, following all symlinks, and resolving @code{.} and @code{..}
26176components, and appending the @file{-gdb.@var{ext}} suffix.
26177If this file exists and is readable, @value{GDBN} will evaluate it as a
26178script in the specified extension language.
26179
26180If this file does not exist, then @value{GDBN} will look for
26181@var{script-name} file in all of the directories as specified below.
26182
26183Note that loading of these files requires an accordingly configured
26184@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
26185
26186For object files using @file{.exe} suffix @value{GDBN} tries to load first the
26187scripts normally according to its @file{.exe} filename. But if no scripts are
26188found @value{GDBN} also tries script filenames matching the object file without
26189its @file{.exe} suffix. This @file{.exe} stripping is case insensitive and it
26190is attempted on any platform. This makes the script filenames compatible
26191between Unix and MS-Windows hosts.
26192
26193@table @code
26194@anchor{set auto-load scripts-directory}
26195@kindex set auto-load scripts-directory
26196@item set auto-load scripts-directory @r{[}@var{directories}@r{]}
26197Control @value{GDBN} auto-loaded scripts location. Multiple directory entries
26198may be delimited by the host platform path separator in use
26199(@samp{:} on Unix, @samp{;} on MS-Windows and MS-DOS).
26200
26201Each entry here needs to be covered also by the security setting
26202@code{set auto-load safe-path} (@pxref{set auto-load safe-path}).
26203
26204@anchor{with-auto-load-dir}
26205This variable defaults to @file{$debugdir:$datadir/auto-load}. The default
26206@code{set auto-load safe-path} value can be also overriden by @value{GDBN}
26207configuration option @option{--with-auto-load-dir}.
26208
26209Any reference to @file{$debugdir} will get replaced by
26210@var{debug-file-directory} value (@pxref{Separate Debug Files}) and any
26211reference to @file{$datadir} will get replaced by @var{data-directory} which is
26212determined at @value{GDBN} startup (@pxref{Data Files}). @file{$debugdir} and
26213@file{$datadir} must be placed as a directory component --- either alone or
26214delimited by @file{/} or @file{\} directory separators, depending on the host
26215platform.
26216
26217The list of directories uses path separator (@samp{:} on GNU and Unix
26218systems, @samp{;} on MS-Windows and MS-DOS) to separate directories, similarly
26219to the @env{PATH} environment variable.
26220
26221@anchor{show auto-load scripts-directory}
26222@kindex show auto-load scripts-directory
26223@item show auto-load scripts-directory
26224Show @value{GDBN} auto-loaded scripts location.
f10c5b19
JK
26225
26226@anchor{add-auto-load-scripts-directory}
26227@kindex add-auto-load-scripts-directory
26228@item add-auto-load-scripts-directory @r{[}@var{directories}@dots{}@r{]}
26229Add an entry (or list of entries) to the list of auto-loaded scripts locations.
26230Multiple entries may be delimited by the host platform path separator in use.
71b8c845
DE
26231@end table
26232
26233@value{GDBN} does not track which files it has already auto-loaded this way.
26234@value{GDBN} will load the associated script every time the corresponding
26235@var{objfile} is opened.
26236So your @file{-gdb.@var{ext}} file should be careful to avoid errors if it
26237is evaluated more than once.
26238
26239@node dotdebug_gdb_scripts section
26240@subsection The @code{.debug_gdb_scripts} section
26241@cindex @code{.debug_gdb_scripts} section
26242
26243For systems using file formats like ELF and COFF,
26244when @value{GDBN} loads a new object file
26245it will look for a special section named @code{.debug_gdb_scripts}.
9f050062
DE
26246If this section exists, its contents is a list of null-terminated entries
26247specifying scripts to load. Each entry begins with a non-null prefix byte that
26248specifies the kind of entry, typically the extension language and whether the
26249script is in a file or inlined in @code{.debug_gdb_scripts}.
71b8c845 26250
9f050062
DE
26251The following entries are supported:
26252
26253@table @code
26254@item SECTION_SCRIPT_ID_PYTHON_FILE = 1
26255@item SECTION_SCRIPT_ID_SCHEME_FILE = 3
26256@item SECTION_SCRIPT_ID_PYTHON_TEXT = 4
26257@item SECTION_SCRIPT_ID_SCHEME_TEXT = 6
26258@end table
26259
26260@subsubsection Script File Entries
26261
26262If the entry specifies a file, @value{GDBN} will look for the file first
26263in the current directory and then along the source search path
71b8c845
DE
26264(@pxref{Source Path, ,Specifying Source Directories}),
26265except that @file{$cdir} is not searched, since the compilation
26266directory is not relevant to scripts.
26267
9f050062 26268File entries can be placed in section @code{.debug_gdb_scripts} with,
71b8c845
DE
26269for example, this GCC macro for Python scripts.
26270
26271@example
26272/* Note: The "MS" section flags are to remove duplicates. */
26273#define DEFINE_GDB_PY_SCRIPT(script_name) \
26274 asm("\
26275.pushsection \".debug_gdb_scripts\", \"MS\",@@progbits,1\n\
26276.byte 1 /* Python */\n\
26277.asciz \"" script_name "\"\n\
26278.popsection \n\
26279");
26280@end example
26281
26282@noindent
ed3ef339 26283For Guile scripts, replace @code{.byte 1} with @code{.byte 3}.
71b8c845
DE
26284Then one can reference the macro in a header or source file like this:
26285
26286@example
26287DEFINE_GDB_PY_SCRIPT ("my-app-scripts.py")
26288@end example
26289
26290The script name may include directories if desired.
26291
26292Note that loading of this script file also requires accordingly configured
26293@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
26294
26295If the macro invocation is put in a header, any application or library
26296using this header will get a reference to the specified script,
26297and with the use of @code{"MS"} attributes on the section, the linker
26298will remove duplicates.
26299
9f050062
DE
26300@subsubsection Script Text Entries
26301
26302Script text entries allow to put the executable script in the entry
26303itself instead of loading it from a file.
26304The first line of the entry, everything after the prefix byte and up to
26305the first newline (@code{0xa}) character, is the script name, and must not
26306contain any kind of space character, e.g., spaces or tabs.
26307The rest of the entry, up to the trailing null byte, is the script to
26308execute in the specified language. The name needs to be unique among
26309all script names, as @value{GDBN} executes each script only once based
26310on its name.
26311
26312Here is an example from file @file{py-section-script.c} in the @value{GDBN}
26313testsuite.
26314
26315@example
26316#include "symcat.h"
26317#include "gdb/section-scripts.h"
26318asm(
26319".pushsection \".debug_gdb_scripts\", \"MS\",@@progbits,1\n"
26320".byte " XSTRING (SECTION_SCRIPT_ID_PYTHON_TEXT) "\n"
26321".ascii \"gdb.inlined-script\\n\"\n"
26322".ascii \"class test_cmd (gdb.Command):\\n\"\n"
26323".ascii \" def __init__ (self):\\n\"\n"
26324".ascii \" super (test_cmd, self).__init__ ("
26325 "\\\"test-cmd\\\", gdb.COMMAND_OBSCURE)\\n\"\n"
26326".ascii \" def invoke (self, arg, from_tty):\\n\"\n"
26327".ascii \" print (\\\"test-cmd output, arg = %s\\\" % arg)\\n\"\n"
26328".ascii \"test_cmd ()\\n\"\n"
26329".byte 0\n"
26330".popsection\n"
26331);
26332@end example
26333
26334Loading of inlined scripts requires a properly configured
26335@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
26336The path to specify in @code{auto-load safe-path} is the path of the file
26337containing the @code{.debug_gdb_scripts} section.
26338
71b8c845
DE
26339@node Which flavor to choose?
26340@subsection Which flavor to choose?
26341
26342Given the multiple ways of auto-loading extensions, it might not always
26343be clear which one to choose. This section provides some guidance.
26344
26345@noindent
26346Benefits of the @file{-gdb.@var{ext}} way:
26347
26348@itemize @bullet
26349@item
26350Can be used with file formats that don't support multiple sections.
26351
26352@item
26353Ease of finding scripts for public libraries.
26354
26355Scripts specified in the @code{.debug_gdb_scripts} section are searched for
26356in the source search path.
26357For publicly installed libraries, e.g., @file{libstdc++}, there typically
26358isn't a source directory in which to find the script.
26359
26360@item
26361Doesn't require source code additions.
26362@end itemize
26363
26364@noindent
26365Benefits of the @code{.debug_gdb_scripts} way:
26366
26367@itemize @bullet
26368@item
26369Works with static linking.
26370
26371Scripts for libraries done the @file{-gdb.@var{ext}} way require an objfile to
26372trigger their loading. When an application is statically linked the only
26373objfile available is the executable, and it is cumbersome to attach all the
26374scripts from all the input libraries to the executable's
26375@file{-gdb.@var{ext}} script.
26376
26377@item
26378Works with classes that are entirely inlined.
26379
26380Some classes can be entirely inlined, and thus there may not be an associated
26381shared library to attach a @file{-gdb.@var{ext}} script to.
26382
26383@item
26384Scripts needn't be copied out of the source tree.
26385
26386In some circumstances, apps can be built out of large collections of internal
26387libraries, and the build infrastructure necessary to install the
26388@file{-gdb.@var{ext}} scripts in a place where @value{GDBN} can find them is
26389cumbersome. It may be easier to specify the scripts in the
26390@code{.debug_gdb_scripts} section as relative paths, and add a path to the
26391top of the source tree to the source search path.
26392@end itemize
26393
ed3ef339
DE
26394@node Multiple Extension Languages
26395@section Multiple Extension Languages
26396
26397The Guile and Python extension languages do not share any state,
26398and generally do not interfere with each other.
26399There are some things to be aware of, however.
26400
26401@subsection Python comes first
26402
26403Python was @value{GDBN}'s first extension language, and to avoid breaking
26404existing behaviour Python comes first. This is generally solved by the
26405``first one wins'' principle. @value{GDBN} maintains a list of enabled
26406extension languages, and when it makes a call to an extension language,
26407(say to pretty-print a value), it tries each in turn until an extension
26408language indicates it has performed the request (e.g., has returned the
26409pretty-printed form of a value).
26410This extends to errors while performing such requests: If an error happens
26411while, for example, trying to pretty-print an object then the error is
26412reported and any following extension languages are not tried.
26413
5a56e9c5
DE
26414@node Aliases
26415@section Creating new spellings of existing commands
26416@cindex aliases for commands
26417
26418It is often useful to define alternate spellings of existing commands.
26419For example, if a new @value{GDBN} command defined in Python has
26420a long name to type, it is handy to have an abbreviated version of it
26421that involves less typing.
26422
26423@value{GDBN} itself uses aliases. For example @samp{s} is an alias
26424of the @samp{step} command even though it is otherwise an ambiguous
26425abbreviation of other commands like @samp{set} and @samp{show}.
26426
26427Aliases are also used to provide shortened or more common versions
26428of multi-word commands. For example, @value{GDBN} provides the
26429@samp{tty} alias of the @samp{set inferior-tty} command.
26430
26431You can define a new alias with the @samp{alias} command.
26432
26433@table @code
26434
26435@kindex alias
26436@item alias [-a] [--] @var{ALIAS} = @var{COMMAND}
26437
26438@end table
26439
26440@var{ALIAS} specifies the name of the new alias.
26441Each word of @var{ALIAS} must consist of letters, numbers, dashes and
26442underscores.
26443
26444@var{COMMAND} specifies the name of an existing command
26445that is being aliased.
26446
26447The @samp{-a} option specifies that the new alias is an abbreviation
26448of the command. Abbreviations are not shown in command
26449lists displayed by the @samp{help} command.
26450
26451The @samp{--} option specifies the end of options,
26452and is useful when @var{ALIAS} begins with a dash.
26453
26454Here is a simple example showing how to make an abbreviation
26455of a command so that there is less to type.
26456Suppose you were tired of typing @samp{disas}, the current
26457shortest unambiguous abbreviation of the @samp{disassemble} command
26458and you wanted an even shorter version named @samp{di}.
26459The following will accomplish this.
26460
26461@smallexample
26462(gdb) alias -a di = disas
26463@end smallexample
26464
26465Note that aliases are different from user-defined commands.
26466With a user-defined command, you also need to write documentation
26467for it with the @samp{document} command.
26468An alias automatically picks up the documentation of the existing command.
26469
26470Here is an example where we make @samp{elms} an abbreviation of
26471@samp{elements} in the @samp{set print elements} command.
26472This is to show that you can make an abbreviation of any part
26473of a command.
26474
26475@smallexample
26476(gdb) alias -a set print elms = set print elements
26477(gdb) alias -a show print elms = show print elements
26478(gdb) set p elms 20
26479(gdb) show p elms
26480Limit on string chars or array elements to print is 200.
26481@end smallexample
26482
26483Note that if you are defining an alias of a @samp{set} command,
26484and you want to have an alias for the corresponding @samp{show}
26485command, then you need to define the latter separately.
26486
26487Unambiguously abbreviated commands are allowed in @var{COMMAND} and
26488@var{ALIAS}, just as they are normally.
26489
26490@smallexample
26491(gdb) alias -a set pr elms = set p ele
26492@end smallexample
26493
26494Finally, here is an example showing the creation of a one word
26495alias for a more complex command.
26496This creates alias @samp{spe} of the command @samp{set print elements}.
26497
26498@smallexample
26499(gdb) alias spe = set print elements
26500(gdb) spe 20
26501@end smallexample
26502
21c294e6
AC
26503@node Interpreters
26504@chapter Command Interpreters
26505@cindex command interpreters
26506
26507@value{GDBN} supports multiple command interpreters, and some command
26508infrastructure to allow users or user interface writers to switch
26509between interpreters or run commands in other interpreters.
26510
26511@value{GDBN} currently supports two command interpreters, the console
26512interpreter (sometimes called the command-line interpreter or @sc{cli})
26513and the machine interface interpreter (or @sc{gdb/mi}). This manual
26514describes both of these interfaces in great detail.
26515
26516By default, @value{GDBN} will start with the console interpreter.
26517However, the user may choose to start @value{GDBN} with another
26518interpreter by specifying the @option{-i} or @option{--interpreter}
26519startup options. Defined interpreters include:
26520
26521@table @code
26522@item console
26523@cindex console interpreter
26524The traditional console or command-line interpreter. This is the most often
26525used interpreter with @value{GDBN}. With no interpreter specified at runtime,
26526@value{GDBN} will use this interpreter.
26527
26528@item mi
26529@cindex mi interpreter
b4be1b06 26530The newest @sc{gdb/mi} interface (currently @code{mi3}). Used primarily
21c294e6
AC
26531by programs wishing to use @value{GDBN} as a backend for a debugger GUI
26532or an IDE. For more information, see @ref{GDB/MI, ,The @sc{gdb/mi}
26533Interface}.
26534
b4be1b06
SM
26535@item mi3
26536@cindex mi3 interpreter
26537The @sc{gdb/mi} interface introduced in @value{GDBN} 9.1.
26538
21c294e6
AC
26539@item mi2
26540@cindex mi2 interpreter
b4be1b06 26541The @sc{gdb/mi} interface introduced in @value{GDBN} 6.0.
21c294e6
AC
26542
26543@item mi1
26544@cindex mi1 interpreter
b4be1b06 26545The @sc{gdb/mi} interface introduced in @value{GDBN} 5.1.
21c294e6
AC
26546
26547@end table
26548
26549@cindex invoke another interpreter
21c294e6
AC
26550
26551@kindex interpreter-exec
86f78169
PA
26552You may execute commands in any interpreter from the current
26553interpreter using the appropriate command. If you are running the
26554console interpreter, simply use the @code{interpreter-exec} command:
21c294e6
AC
26555
26556@smallexample
26557interpreter-exec mi "-data-list-register-names"
26558@end smallexample
26559
26560@sc{gdb/mi} has a similar command, although it is only available in versions of
26561@value{GDBN} which support @sc{gdb/mi} version 2 (or greater).
26562
86f78169
PA
26563Note that @code{interpreter-exec} only changes the interpreter for the
26564duration of the specified command. It does not change the interpreter
26565permanently.
26566
26567@cindex start a new independent interpreter
26568
26569Although you may only choose a single interpreter at startup, it is
26570possible to run an independent interpreter on a specified input/output
26571device (usually a tty).
26572
26573For example, consider a debugger GUI or IDE that wants to provide a
26574@value{GDBN} console view. It may do so by embedding a terminal
26575emulator widget in its GUI, starting @value{GDBN} in the traditional
26576command-line mode with stdin/stdout/stderr redirected to that
26577terminal, and then creating an MI interpreter running on a specified
26578input/output device. The console interpreter created by @value{GDBN}
26579at startup handles commands the user types in the terminal widget,
26580while the GUI controls and synchronizes state with @value{GDBN} using
26581the separate MI interpreter.
26582
26583To start a new secondary @dfn{user interface} running MI, use the
26584@code{new-ui} command:
26585
26586@kindex new-ui
26587@cindex new user interface
26588@smallexample
26589new-ui @var{interpreter} @var{tty}
26590@end smallexample
26591
26592The @var{interpreter} parameter specifies the interpreter to run.
26593This accepts the same values as the @code{interpreter-exec} command.
26594For example, @samp{console}, @samp{mi}, @samp{mi2}, etc. The
26595@var{tty} parameter specifies the name of the bidirectional file the
26596interpreter uses for input/output, usually the name of a
26597pseudoterminal slave on Unix systems. For example:
26598
26599@smallexample
26600(@value{GDBP}) new-ui mi /dev/pts/9
26601@end smallexample
26602
26603@noindent
26604runs an MI interpreter on @file{/dev/pts/9}.
26605
8e04817f
AC
26606@node TUI
26607@chapter @value{GDBN} Text User Interface
26608@cindex TUI
d0d5df6f 26609@cindex Text User Interface
c906108c 26610
8e04817f
AC
26611@menu
26612* TUI Overview:: TUI overview
26613* TUI Keys:: TUI key bindings
7cf36c78 26614* TUI Single Key Mode:: TUI single key mode
db2e3e2e 26615* TUI Commands:: TUI-specific commands
8e04817f
AC
26616* TUI Configuration:: TUI configuration variables
26617@end menu
c906108c 26618
46ba6afa 26619The @value{GDBN} Text User Interface (TUI) is a terminal
d0d5df6f
AC
26620interface which uses the @code{curses} library to show the source
26621file, the assembly output, the program registers and @value{GDBN}
46ba6afa
BW
26622commands in separate text windows. The TUI mode is supported only
26623on platforms where a suitable version of the @code{curses} library
26624is available.
d0d5df6f 26625
46ba6afa 26626The TUI mode is enabled by default when you invoke @value{GDBN} as
217bff3e 26627@samp{@value{GDBP} -tui}.
46ba6afa 26628You can also switch in and out of TUI mode while @value{GDBN} runs by
a4ea0946 26629using various TUI commands and key bindings, such as @command{tui
bcd8537c 26630enable} or @kbd{C-x C-a}. @xref{TUI Commands, ,TUI Commands}, and
a4ea0946 26631@ref{TUI Keys, ,TUI Key Bindings}.
c906108c 26632
8e04817f 26633@node TUI Overview
79a6e687 26634@section TUI Overview
c906108c 26635
46ba6afa 26636In TUI mode, @value{GDBN} can display several text windows:
c906108c 26637
8e04817f
AC
26638@table @emph
26639@item command
26640This window is the @value{GDBN} command window with the @value{GDBN}
46ba6afa
BW
26641prompt and the @value{GDBN} output. The @value{GDBN} input is still
26642managed using readline.
c906108c 26643
8e04817f
AC
26644@item source
26645The source window shows the source file of the program. The current
46ba6afa 26646line and active breakpoints are displayed in this window.
c906108c 26647
8e04817f
AC
26648@item assembly
26649The assembly window shows the disassembly output of the program.
c906108c 26650
8e04817f 26651@item register
46ba6afa
BW
26652This window shows the processor registers. Registers are highlighted
26653when their values change.
c906108c
SS
26654@end table
26655
269c21fe 26656The source and assembly windows show the current program position
46ba6afa
BW
26657by highlighting the current line and marking it with a @samp{>} marker.
26658Breakpoints are indicated with two markers. The first marker
269c21fe
SC
26659indicates the breakpoint type:
26660
26661@table @code
26662@item B
26663Breakpoint which was hit at least once.
26664
26665@item b
26666Breakpoint which was never hit.
26667
26668@item H
26669Hardware breakpoint which was hit at least once.
26670
26671@item h
26672Hardware breakpoint which was never hit.
269c21fe
SC
26673@end table
26674
26675The second marker indicates whether the breakpoint is enabled or not:
26676
26677@table @code
26678@item +
26679Breakpoint is enabled.
26680
26681@item -
26682Breakpoint is disabled.
269c21fe
SC
26683@end table
26684
46ba6afa
BW
26685The source, assembly and register windows are updated when the current
26686thread changes, when the frame changes, or when the program counter
26687changes.
26688
26689These windows are not all visible at the same time. The command
26690window is always visible. The others can be arranged in several
26691layouts:
c906108c 26692
8e04817f
AC
26693@itemize @bullet
26694@item
46ba6afa 26695source only,
2df3850c 26696
8e04817f 26697@item
46ba6afa 26698assembly only,
8e04817f
AC
26699
26700@item
46ba6afa 26701source and assembly,
8e04817f
AC
26702
26703@item
46ba6afa 26704source and registers, or
c906108c 26705
8e04817f 26706@item
46ba6afa 26707assembly and registers.
8e04817f 26708@end itemize
c906108c 26709
46ba6afa 26710A status line above the command window shows the following information:
b7bb15bc
SC
26711
26712@table @emph
26713@item target
46ba6afa 26714Indicates the current @value{GDBN} target.
b7bb15bc
SC
26715(@pxref{Targets, ,Specifying a Debugging Target}).
26716
26717@item process
46ba6afa 26718Gives the current process or thread number.
b7bb15bc
SC
26719When no process is being debugged, this field is set to @code{No process}.
26720
26721@item function
26722Gives the current function name for the selected frame.
26723The name is demangled if demangling is turned on (@pxref{Print Settings}).
46ba6afa 26724When there is no symbol corresponding to the current program counter,
b7bb15bc
SC
26725the string @code{??} is displayed.
26726
26727@item line
26728Indicates the current line number for the selected frame.
46ba6afa 26729When the current line number is not known, the string @code{??} is displayed.
b7bb15bc
SC
26730
26731@item pc
26732Indicates the current program counter address.
b7bb15bc
SC
26733@end table
26734
8e04817f
AC
26735@node TUI Keys
26736@section TUI Key Bindings
26737@cindex TUI key bindings
c906108c 26738
8e04817f 26739The TUI installs several key bindings in the readline keymaps
39037522
TT
26740@ifset SYSTEM_READLINE
26741(@pxref{Command Line Editing, , , rluserman, GNU Readline Library}).
26742@end ifset
26743@ifclear SYSTEM_READLINE
26744(@pxref{Command Line Editing}).
26745@end ifclear
26746The following key bindings are installed for both TUI mode and the
26747@value{GDBN} standard mode.
c906108c 26748
8e04817f
AC
26749@table @kbd
26750@kindex C-x C-a
26751@item C-x C-a
26752@kindex C-x a
26753@itemx C-x a
26754@kindex C-x A
26755@itemx C-x A
46ba6afa
BW
26756Enter or leave the TUI mode. When leaving the TUI mode,
26757the curses window management stops and @value{GDBN} operates using
26758its standard mode, writing on the terminal directly. When reentering
26759the TUI mode, control is given back to the curses windows.
8e04817f 26760The screen is then refreshed.
c906108c 26761
8e04817f
AC
26762@kindex C-x 1
26763@item C-x 1
26764Use a TUI layout with only one window. The layout will
26765either be @samp{source} or @samp{assembly}. When the TUI mode
26766is not active, it will switch to the TUI mode.
2df3850c 26767
8e04817f 26768Think of this key binding as the Emacs @kbd{C-x 1} binding.
c906108c 26769
8e04817f
AC
26770@kindex C-x 2
26771@item C-x 2
26772Use a TUI layout with at least two windows. When the current
46ba6afa 26773layout already has two windows, the next layout with two windows is used.
8e04817f
AC
26774When a new layout is chosen, one window will always be common to the
26775previous layout and the new one.
c906108c 26776
8e04817f 26777Think of it as the Emacs @kbd{C-x 2} binding.
2df3850c 26778
72ffddc9
SC
26779@kindex C-x o
26780@item C-x o
26781Change the active window. The TUI associates several key bindings
46ba6afa 26782(like scrolling and arrow keys) with the active window. This command
72ffddc9
SC
26783gives the focus to the next TUI window.
26784
26785Think of it as the Emacs @kbd{C-x o} binding.
26786
7cf36c78
SC
26787@kindex C-x s
26788@item C-x s
46ba6afa
BW
26789Switch in and out of the TUI SingleKey mode that binds single
26790keys to @value{GDBN} commands (@pxref{TUI Single Key Mode}).
c906108c
SS
26791@end table
26792
46ba6afa 26793The following key bindings only work in the TUI mode:
5d161b24 26794
46ba6afa 26795@table @asis
8e04817f 26796@kindex PgUp
46ba6afa 26797@item @key{PgUp}
8e04817f 26798Scroll the active window one page up.
c906108c 26799
8e04817f 26800@kindex PgDn
46ba6afa 26801@item @key{PgDn}
8e04817f 26802Scroll the active window one page down.
c906108c 26803
8e04817f 26804@kindex Up
46ba6afa 26805@item @key{Up}
8e04817f 26806Scroll the active window one line up.
c906108c 26807
8e04817f 26808@kindex Down
46ba6afa 26809@item @key{Down}
8e04817f 26810Scroll the active window one line down.
c906108c 26811
8e04817f 26812@kindex Left
46ba6afa 26813@item @key{Left}
8e04817f 26814Scroll the active window one column left.
c906108c 26815
8e04817f 26816@kindex Right
46ba6afa 26817@item @key{Right}
8e04817f 26818Scroll the active window one column right.
c906108c 26819
8e04817f 26820@kindex C-L
46ba6afa 26821@item @kbd{C-L}
8e04817f 26822Refresh the screen.
8e04817f 26823@end table
c906108c 26824
46ba6afa
BW
26825Because the arrow keys scroll the active window in the TUI mode, they
26826are not available for their normal use by readline unless the command
26827window has the focus. When another window is active, you must use
26828other readline key bindings such as @kbd{C-p}, @kbd{C-n}, @kbd{C-b}
26829and @kbd{C-f} to control the command window.
8e04817f 26830
7cf36c78
SC
26831@node TUI Single Key Mode
26832@section TUI Single Key Mode
26833@cindex TUI single key mode
26834
46ba6afa
BW
26835The TUI also provides a @dfn{SingleKey} mode, which binds several
26836frequently used @value{GDBN} commands to single keys. Type @kbd{C-x s} to
26837switch into this mode, where the following key bindings are used:
7cf36c78
SC
26838
26839@table @kbd
26840@kindex c @r{(SingleKey TUI key)}
26841@item c
26842continue
26843
26844@kindex d @r{(SingleKey TUI key)}
26845@item d
26846down
26847
26848@kindex f @r{(SingleKey TUI key)}
26849@item f
26850finish
26851
26852@kindex n @r{(SingleKey TUI key)}
26853@item n
26854next
26855
a5afdb16
RK
26856@kindex o @r{(SingleKey TUI key)}
26857@item o
26858nexti. The shortcut letter @samp{o} stands for ``step Over''.
26859
7cf36c78
SC
26860@kindex q @r{(SingleKey TUI key)}
26861@item q
46ba6afa 26862exit the SingleKey mode.
7cf36c78
SC
26863
26864@kindex r @r{(SingleKey TUI key)}
26865@item r
26866run
26867
26868@kindex s @r{(SingleKey TUI key)}
26869@item s
26870step
26871
a5afdb16
RK
26872@kindex i @r{(SingleKey TUI key)}
26873@item i
26874stepi. The shortcut letter @samp{i} stands for ``step Into''.
26875
7cf36c78
SC
26876@kindex u @r{(SingleKey TUI key)}
26877@item u
26878up
26879
26880@kindex v @r{(SingleKey TUI key)}
26881@item v
26882info locals
26883
26884@kindex w @r{(SingleKey TUI key)}
26885@item w
26886where
7cf36c78
SC
26887@end table
26888
26889Other keys temporarily switch to the @value{GDBN} command prompt.
26890The key that was pressed is inserted in the editing buffer so that
26891it is possible to type most @value{GDBN} commands without interaction
46ba6afa
BW
26892with the TUI SingleKey mode. Once the command is entered the TUI
26893SingleKey mode is restored. The only way to permanently leave
7f9087cb 26894this mode is by typing @kbd{q} or @kbd{C-x s}.
7cf36c78
SC
26895
26896
8e04817f 26897@node TUI Commands
db2e3e2e 26898@section TUI-specific Commands
8e04817f
AC
26899@cindex TUI commands
26900
26901The TUI has specific commands to control the text windows.
46ba6afa
BW
26902These commands are always available, even when @value{GDBN} is not in
26903the TUI mode. When @value{GDBN} is in the standard mode, most
26904of these commands will automatically switch to the TUI mode.
c906108c 26905
ff12863f
PA
26906Note that if @value{GDBN}'s @code{stdout} is not connected to a
26907terminal, or @value{GDBN} has been started with the machine interface
26908interpreter (@pxref{GDB/MI, ,The @sc{gdb/mi} Interface}), most of
26909these commands will fail with an error, because it would not be
26910possible or desirable to enable curses window management.
26911
c906108c 26912@table @code
a4ea0946
AB
26913@item tui enable
26914@kindex tui enable
26915Activate TUI mode. The last active TUI window layout will be used if
26916TUI mode has prevsiouly been used in the current debugging session,
26917otherwise a default layout is used.
26918
26919@item tui disable
26920@kindex tui disable
26921Disable TUI mode, returning to the console interpreter.
26922
3d757584
SC
26923@item info win
26924@kindex info win
26925List and give the size of all displayed windows.
26926
6008fc5f 26927@item layout @var{name}
4644b6e3 26928@kindex layout
6008fc5f
AB
26929Changes which TUI windows are displayed. In each layout the command
26930window is always displayed, the @var{name} parameter controls which
26931additional windows are displayed, and can be any of the following:
26932
26933@table @code
26934@item next
8e04817f 26935Display the next layout.
2df3850c 26936
6008fc5f 26937@item prev
8e04817f 26938Display the previous layout.
c906108c 26939
6008fc5f
AB
26940@item src
26941Display the source and command windows.
c906108c 26942
6008fc5f
AB
26943@item asm
26944Display the assembly and command windows.
c906108c 26945
6008fc5f
AB
26946@item split
26947Display the source, assembly, and command windows.
c906108c 26948
6008fc5f
AB
26949@item regs
26950When in @code{src} layout display the register, source, and command
26951windows. When in @code{asm} or @code{split} layout display the
26952register, assembler, and command windows.
26953@end table
8e04817f 26954
6008fc5f 26955@item focus @var{name}
8e04817f 26956@kindex focus
6008fc5f
AB
26957Changes which TUI window is currently active for scrolling. The
26958@var{name} parameter can be any of the following:
26959
26960@table @code
26961@item next
46ba6afa
BW
26962Make the next window active for scrolling.
26963
6008fc5f 26964@item prev
46ba6afa
BW
26965Make the previous window active for scrolling.
26966
6008fc5f 26967@item src
46ba6afa
BW
26968Make the source window active for scrolling.
26969
6008fc5f 26970@item asm
46ba6afa
BW
26971Make the assembly window active for scrolling.
26972
6008fc5f 26973@item regs
46ba6afa
BW
26974Make the register window active for scrolling.
26975
6008fc5f 26976@item cmd
46ba6afa 26977Make the command window active for scrolling.
6008fc5f 26978@end table
c906108c 26979
8e04817f
AC
26980@item refresh
26981@kindex refresh
7f9087cb 26982Refresh the screen. This is similar to typing @kbd{C-L}.
c906108c 26983
51f0e40d 26984@item tui reg @var{group}
6a1b180d 26985@kindex tui reg
51f0e40d
AB
26986Changes the register group displayed in the tui register window to
26987@var{group}. If the register window is not currently displayed this
26988command will cause the register window to be displayed. The list of
26989register groups, as well as their order is target specific. The
26990following groups are available on most targets:
26991@table @code
26992@item next
26993Repeatedly selecting this group will cause the display to cycle
26994through all of the available register groups.
26995
26996@item prev
26997Repeatedly selecting this group will cause the display to cycle
26998through all of the available register groups in the reverse order to
26999@var{next}.
27000
27001@item general
27002Display the general registers.
27003@item float
27004Display the floating point registers.
27005@item system
27006Display the system registers.
27007@item vector
27008Display the vector registers.
27009@item all
27010Display all registers.
27011@end table
6a1b180d 27012
8e04817f
AC
27013@item update
27014@kindex update
27015Update the source window and the current execution point.
c906108c 27016
8e04817f
AC
27017@item winheight @var{name} +@var{count}
27018@itemx winheight @var{name} -@var{count}
27019@kindex winheight
27020Change the height of the window @var{name} by @var{count}
27021lines. Positive counts increase the height, while negative counts
bf555842
EZ
27022decrease it. The @var{name} parameter can be one of @code{src} (the
27023source window), @code{cmd} (the command window), @code{asm} (the
27024disassembly window), or @code{regs} (the register display window).
d6677607 27025@end table
2df3850c 27026
8e04817f 27027@node TUI Configuration
79a6e687 27028@section TUI Configuration Variables
8e04817f 27029@cindex TUI configuration variables
c906108c 27030
46ba6afa 27031Several configuration variables control the appearance of TUI windows.
c906108c 27032
8e04817f
AC
27033@table @code
27034@item set tui border-kind @var{kind}
27035@kindex set tui border-kind
27036Select the border appearance for the source, assembly and register windows.
27037The possible values are the following:
27038@table @code
27039@item space
27040Use a space character to draw the border.
c906108c 27041
8e04817f 27042@item ascii
46ba6afa 27043Use @sc{ascii} characters @samp{+}, @samp{-} and @samp{|} to draw the border.
c906108c 27044
8e04817f
AC
27045@item acs
27046Use the Alternate Character Set to draw the border. The border is
27047drawn using character line graphics if the terminal supports them.
8e04817f 27048@end table
c78b4128 27049
8e04817f
AC
27050@item set tui border-mode @var{mode}
27051@kindex set tui border-mode
46ba6afa
BW
27052@itemx set tui active-border-mode @var{mode}
27053@kindex set tui active-border-mode
27054Select the display attributes for the borders of the inactive windows
27055or the active window. The @var{mode} can be one of the following:
8e04817f
AC
27056@table @code
27057@item normal
27058Use normal attributes to display the border.
c906108c 27059
8e04817f
AC
27060@item standout
27061Use standout mode.
c906108c 27062
8e04817f
AC
27063@item reverse
27064Use reverse video mode.
c906108c 27065
8e04817f
AC
27066@item half
27067Use half bright mode.
c906108c 27068
8e04817f
AC
27069@item half-standout
27070Use half bright and standout mode.
c906108c 27071
8e04817f
AC
27072@item bold
27073Use extra bright or bold mode.
c78b4128 27074
8e04817f
AC
27075@item bold-standout
27076Use extra bright or bold and standout mode.
8e04817f 27077@end table
7806cea7
TT
27078
27079@item set tui tab-width @var{nchars}
27080@kindex set tui tab-width
27081@kindex tabset
27082Set the width of tab stops to be @var{nchars} characters. This
27083setting affects the display of TAB characters in the source and
27084assembly windows.
27085@end table
c78b4128 27086
8e04817f
AC
27087@node Emacs
27088@chapter Using @value{GDBN} under @sc{gnu} Emacs
c78b4128 27089
8e04817f
AC
27090@cindex Emacs
27091@cindex @sc{gnu} Emacs
27092A special interface allows you to use @sc{gnu} Emacs to view (and
27093edit) the source files for the program you are debugging with
27094@value{GDBN}.
c906108c 27095
8e04817f
AC
27096To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the
27097executable file you want to debug as an argument. This command starts
27098@value{GDBN} as a subprocess of Emacs, with input and output through a newly
27099created Emacs buffer.
27100@c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.)
c906108c 27101
5e252a2e 27102Running @value{GDBN} under Emacs can be just like running @value{GDBN} normally except for two
8e04817f 27103things:
c906108c 27104
8e04817f
AC
27105@itemize @bullet
27106@item
5e252a2e
NR
27107All ``terminal'' input and output goes through an Emacs buffer, called
27108the GUD buffer.
c906108c 27109
8e04817f
AC
27110This applies both to @value{GDBN} commands and their output, and to the input
27111and output done by the program you are debugging.
bf0184be 27112
8e04817f
AC
27113This is useful because it means that you can copy the text of previous
27114commands and input them again; you can even use parts of the output
27115in this way.
bf0184be 27116
8e04817f
AC
27117All the facilities of Emacs' Shell mode are available for interacting
27118with your program. In particular, you can send signals the usual
27119way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a
27120stop.
bf0184be
ND
27121
27122@item
8e04817f 27123@value{GDBN} displays source code through Emacs.
bf0184be 27124
8e04817f
AC
27125Each time @value{GDBN} displays a stack frame, Emacs automatically finds the
27126source file for that frame and puts an arrow (@samp{=>}) at the
27127left margin of the current line. Emacs uses a separate buffer for
27128source display, and splits the screen to show both your @value{GDBN} session
27129and the source.
bf0184be 27130
8e04817f
AC
27131Explicit @value{GDBN} @code{list} or search commands still produce output as
27132usual, but you probably have no reason to use them from Emacs.
5e252a2e
NR
27133@end itemize
27134
27135We call this @dfn{text command mode}. Emacs 22.1, and later, also uses
27136a graphical mode, enabled by default, which provides further buffers
27137that can control the execution and describe the state of your program.
27138@xref{GDB Graphical Interface,,, Emacs, The @sc{gnu} Emacs Manual}.
c906108c 27139
64fabec2
AC
27140If you specify an absolute file name when prompted for the @kbd{M-x
27141gdb} argument, then Emacs sets your current working directory to where
27142your program resides. If you only specify the file name, then Emacs
7a9dd1b2 27143sets your current working directory to the directory associated
64fabec2
AC
27144with the previous buffer. In this case, @value{GDBN} may find your
27145program by searching your environment's @code{PATH} variable, but on
27146some operating systems it might not find the source. So, although the
27147@value{GDBN} input and output session proceeds normally, the auxiliary
27148buffer does not display the current source and line of execution.
27149
27150The initial working directory of @value{GDBN} is printed on the top
5e252a2e
NR
27151line of the GUD buffer and this serves as a default for the commands
27152that specify files for @value{GDBN} to operate on. @xref{Files,
27153,Commands to Specify Files}.
64fabec2
AC
27154
27155By default, @kbd{M-x gdb} calls the program called @file{gdb}. If you
27156need to call @value{GDBN} by a different name (for example, if you
27157keep several configurations around, with different names) you can
27158customize the Emacs variable @code{gud-gdb-command-name} to run the
27159one you want.
8e04817f 27160
5e252a2e 27161In the GUD buffer, you can use these special Emacs commands in
8e04817f 27162addition to the standard Shell mode commands:
c906108c 27163
8e04817f
AC
27164@table @kbd
27165@item C-h m
5e252a2e 27166Describe the features of Emacs' GUD Mode.
c906108c 27167
64fabec2 27168@item C-c C-s
8e04817f
AC
27169Execute to another source line, like the @value{GDBN} @code{step} command; also
27170update the display window to show the current file and location.
c906108c 27171
64fabec2 27172@item C-c C-n
8e04817f
AC
27173Execute to next source line in this function, skipping all function
27174calls, like the @value{GDBN} @code{next} command. Then update the display window
27175to show the current file and location.
c906108c 27176
64fabec2 27177@item C-c C-i
8e04817f
AC
27178Execute one instruction, like the @value{GDBN} @code{stepi} command; update
27179display window accordingly.
c906108c 27180
8e04817f
AC
27181@item C-c C-f
27182Execute until exit from the selected stack frame, like the @value{GDBN}
27183@code{finish} command.
c906108c 27184
64fabec2 27185@item C-c C-r
8e04817f
AC
27186Continue execution of your program, like the @value{GDBN} @code{continue}
27187command.
b433d00b 27188
64fabec2 27189@item C-c <
8e04817f
AC
27190Go up the number of frames indicated by the numeric argument
27191(@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}),
27192like the @value{GDBN} @code{up} command.
b433d00b 27193
64fabec2 27194@item C-c >
8e04817f
AC
27195Go down the number of frames indicated by the numeric argument, like the
27196@value{GDBN} @code{down} command.
8e04817f 27197@end table
c906108c 27198
7f9087cb 27199In any source file, the Emacs command @kbd{C-x @key{SPC}} (@code{gud-break})
8e04817f 27200tells @value{GDBN} to set a breakpoint on the source line point is on.
c906108c 27201
5e252a2e
NR
27202In text command mode, if you type @kbd{M-x speedbar}, Emacs displays a
27203separate frame which shows a backtrace when the GUD buffer is current.
27204Move point to any frame in the stack and type @key{RET} to make it
27205become the current frame and display the associated source in the
27206source buffer. Alternatively, click @kbd{Mouse-2} to make the
27207selected frame become the current one. In graphical mode, the
27208speedbar displays watch expressions.
64fabec2 27209
8e04817f
AC
27210If you accidentally delete the source-display buffer, an easy way to get
27211it back is to type the command @code{f} in the @value{GDBN} buffer, to
27212request a frame display; when you run under Emacs, this recreates
27213the source buffer if necessary to show you the context of the current
27214frame.
c906108c 27215
8e04817f
AC
27216The source files displayed in Emacs are in ordinary Emacs buffers
27217which are visiting the source files in the usual way. You can edit
27218the files with these buffers if you wish; but keep in mind that @value{GDBN}
27219communicates with Emacs in terms of line numbers. If you add or
27220delete lines from the text, the line numbers that @value{GDBN} knows cease
27221to correspond properly with the code.
b383017d 27222
5e252a2e
NR
27223A more detailed description of Emacs' interaction with @value{GDBN} is
27224given in the Emacs manual (@pxref{Debuggers,,, Emacs, The @sc{gnu}
27225Emacs Manual}).
c906108c 27226
922fbb7b
AC
27227@node GDB/MI
27228@chapter The @sc{gdb/mi} Interface
27229
27230@unnumberedsec Function and Purpose
27231
27232@cindex @sc{gdb/mi}, its purpose
6b5e8c01
NR
27233@sc{gdb/mi} is a line based machine oriented text interface to
27234@value{GDBN} and is activated by specifying using the
27235@option{--interpreter} command line option (@pxref{Mode Options}). It
27236is specifically intended to support the development of systems which
27237use the debugger as just one small component of a larger system.
922fbb7b
AC
27238
27239This chapter is a specification of the @sc{gdb/mi} interface. It is written
27240in the form of a reference manual.
27241
27242Note that @sc{gdb/mi} is still under construction, so some of the
af6eff6f
NR
27243features described below are incomplete and subject to change
27244(@pxref{GDB/MI Development and Front Ends, , @sc{gdb/mi} Development and Front Ends}).
922fbb7b
AC
27245
27246@unnumberedsec Notation and Terminology
27247
27248@cindex notational conventions, for @sc{gdb/mi}
27249This chapter uses the following notation:
27250
27251@itemize @bullet
27252@item
27253@code{|} separates two alternatives.
27254
27255@item
27256@code{[ @var{something} ]} indicates that @var{something} is optional:
27257it may or may not be given.
27258
27259@item
27260@code{( @var{group} )*} means that @var{group} inside the parentheses
27261may repeat zero or more times.
27262
27263@item
27264@code{( @var{group} )+} means that @var{group} inside the parentheses
27265may repeat one or more times.
27266
27267@item
27268@code{"@var{string}"} means a literal @var{string}.
27269@end itemize
27270
27271@ignore
27272@heading Dependencies
27273@end ignore
27274
922fbb7b 27275@menu
c3b108f7 27276* GDB/MI General Design::
922fbb7b
AC
27277* GDB/MI Command Syntax::
27278* GDB/MI Compatibility with CLI::
af6eff6f 27279* GDB/MI Development and Front Ends::
922fbb7b 27280* GDB/MI Output Records::
ef21caaf 27281* GDB/MI Simple Examples::
922fbb7b 27282* GDB/MI Command Description Format::
ef21caaf 27283* GDB/MI Breakpoint Commands::
3fa7bf06 27284* GDB/MI Catchpoint Commands::
a2c02241
NR
27285* GDB/MI Program Context::
27286* GDB/MI Thread Commands::
5d77fe44 27287* GDB/MI Ada Tasking Commands::
a2c02241
NR
27288* GDB/MI Program Execution::
27289* GDB/MI Stack Manipulation::
27290* GDB/MI Variable Objects::
922fbb7b 27291* GDB/MI Data Manipulation::
a2c02241
NR
27292* GDB/MI Tracepoint Commands::
27293* GDB/MI Symbol Query::
351ff01a 27294* GDB/MI File Commands::
922fbb7b
AC
27295@ignore
27296* GDB/MI Kod Commands::
27297* GDB/MI Memory Overlay Commands::
27298* GDB/MI Signal Handling Commands::
27299@end ignore
922fbb7b 27300* GDB/MI Target Manipulation::
a6b151f1 27301* GDB/MI File Transfer Commands::
58d06528 27302* GDB/MI Ada Exceptions Commands::
d192b373 27303* GDB/MI Support Commands::
ef21caaf 27304* GDB/MI Miscellaneous Commands::
922fbb7b
AC
27305@end menu
27306
c3b108f7
VP
27307@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27308@node GDB/MI General Design
27309@section @sc{gdb/mi} General Design
27310@cindex GDB/MI General Design
27311
27312Interaction of a @sc{GDB/MI} frontend with @value{GDBN} involves three
27313parts---commands sent to @value{GDBN}, responses to those commands
27314and notifications. Each command results in exactly one response,
27315indicating either successful completion of the command, or an error.
27316For the commands that do not resume the target, the response contains the
27317requested information. For the commands that resume the target, the
27318response only indicates whether the target was successfully resumed.
27319Notifications is the mechanism for reporting changes in the state of the
27320target, or in @value{GDBN} state, that cannot conveniently be associated with
27321a command and reported as part of that command response.
27322
27323The important examples of notifications are:
27324@itemize @bullet
27325
27326@item
27327Exec notifications. These are used to report changes in
27328target state---when a target is resumed, or stopped. It would not
27329be feasible to include this information in response of resuming
27330commands, because one resume commands can result in multiple events in
27331different threads. Also, quite some time may pass before any event
27332happens in the target, while a frontend needs to know whether the resuming
27333command itself was successfully executed.
27334
27335@item
27336Console output, and status notifications. Console output
27337notifications are used to report output of CLI commands, as well as
27338diagnostics for other commands. Status notifications are used to
27339report the progress of a long-running operation. Naturally, including
27340this information in command response would mean no output is produced
27341until the command is finished, which is undesirable.
27342
27343@item
27344General notifications. Commands may have various side effects on
27345the @value{GDBN} or target state beyond their official purpose. For example,
27346a command may change the selected thread. Although such changes can
27347be included in command response, using notification allows for more
27348orthogonal frontend design.
27349
27350@end itemize
27351
27352There's no guarantee that whenever an MI command reports an error,
27353@value{GDBN} or the target are in any specific state, and especially,
27354the state is not reverted to the state before the MI command was
27355processed. Therefore, whenever an MI command results in an error,
27356we recommend that the frontend refreshes all the information shown in
27357the user interface.
27358
508094de
NR
27359
27360@menu
27361* Context management::
27362* Asynchronous and non-stop modes::
27363* Thread groups::
27364@end menu
27365
27366@node Context management
c3b108f7
VP
27367@subsection Context management
27368
403cb6b1
JB
27369@subsubsection Threads and Frames
27370
c3b108f7
VP
27371In most cases when @value{GDBN} accesses the target, this access is
27372done in context of a specific thread and frame (@pxref{Frames}).
27373Often, even when accessing global data, the target requires that a thread
27374be specified. The CLI interface maintains the selected thread and frame,
27375and supplies them to target on each command. This is convenient,
27376because a command line user would not want to specify that information
27377explicitly on each command, and because user interacts with
27378@value{GDBN} via a single terminal, so no confusion is possible as
27379to what thread and frame are the current ones.
27380
27381In the case of MI, the concept of selected thread and frame is less
27382useful. First, a frontend can easily remember this information
27383itself. Second, a graphical frontend can have more than one window,
27384each one used for debugging a different thread, and the frontend might
27385want to access additional threads for internal purposes. This
27386increases the risk that by relying on implicitly selected thread, the
27387frontend may be operating on a wrong one. Therefore, each MI command
27388should explicitly specify which thread and frame to operate on. To
27389make it possible, each MI command accepts the @samp{--thread} and
5d5658a1
PA
27390@samp{--frame} options, the value to each is @value{GDBN} global
27391identifier for thread and frame to operate on.
c3b108f7
VP
27392
27393Usually, each top-level window in a frontend allows the user to select
27394a thread and a frame, and remembers the user selection for further
27395operations. However, in some cases @value{GDBN} may suggest that the
4034d0ff
AT
27396current thread or frame be changed. For example, when stopping on a
27397breakpoint it is reasonable to switch to the thread where breakpoint is
27398hit. For another example, if the user issues the CLI @samp{thread} or
27399@samp{frame} commands via the frontend, it is desirable to change the
27400frontend's selection to the one specified by user. @value{GDBN}
27401communicates the suggestion to change current thread and frame using the
27402@samp{=thread-selected} notification.
c3b108f7
VP
27403
27404Note that historically, MI shares the selected thread with CLI, so
27405frontends used the @code{-thread-select} to execute commands in the
27406right context. However, getting this to work right is cumbersome. The
27407simplest way is for frontend to emit @code{-thread-select} command
27408before every command. This doubles the number of commands that need
27409to be sent. The alternative approach is to suppress @code{-thread-select}
27410if the selected thread in @value{GDBN} is supposed to be identical to the
27411thread the frontend wants to operate on. However, getting this
27412optimization right can be tricky. In particular, if the frontend
27413sends several commands to @value{GDBN}, and one of the commands changes the
27414selected thread, then the behaviour of subsequent commands will
27415change. So, a frontend should either wait for response from such
27416problematic commands, or explicitly add @code{-thread-select} for
27417all subsequent commands. No frontend is known to do this exactly
27418right, so it is suggested to just always pass the @samp{--thread} and
27419@samp{--frame} options.
27420
403cb6b1
JB
27421@subsubsection Language
27422
27423The execution of several commands depends on which language is selected.
27424By default, the current language (@pxref{show language}) is used.
27425But for commands known to be language-sensitive, it is recommended
27426to use the @samp{--language} option. This option takes one argument,
27427which is the name of the language to use while executing the command.
27428For instance:
27429
27430@smallexample
27431-data-evaluate-expression --language c "sizeof (void*)"
27432^done,value="4"
27433(gdb)
27434@end smallexample
27435
27436The valid language names are the same names accepted by the
27437@samp{set language} command (@pxref{Manually}), excluding @samp{auto},
27438@samp{local} or @samp{unknown}.
27439
508094de 27440@node Asynchronous and non-stop modes
c3b108f7
VP
27441@subsection Asynchronous command execution and non-stop mode
27442
27443On some targets, @value{GDBN} is capable of processing MI commands
27444even while the target is running. This is called @dfn{asynchronous
27445command execution} (@pxref{Background Execution}). The frontend may
27446specify a preferrence for asynchronous execution using the
329ea579 27447@code{-gdb-set mi-async 1} command, which should be emitted before
c3b108f7
VP
27448either running the executable or attaching to the target. After the
27449frontend has started the executable or attached to the target, it can
27450find if asynchronous execution is enabled using the
27451@code{-list-target-features} command.
27452
329ea579
PA
27453@table @code
27454@item -gdb-set mi-async on
27455@item -gdb-set mi-async off
27456Set whether MI is in asynchronous mode.
27457
27458When @code{off}, which is the default, MI execution commands (e.g.,
27459@code{-exec-continue}) are foreground commands, and @value{GDBN} waits
27460for the program to stop before processing further commands.
27461
27462When @code{on}, MI execution commands are background execution
27463commands (e.g., @code{-exec-continue} becomes the equivalent of the
27464@code{c&} CLI command), and so @value{GDBN} is capable of processing
27465MI commands even while the target is running.
27466
27467@item -gdb-show mi-async
27468Show whether MI asynchronous mode is enabled.
27469@end table
27470
27471Note: In @value{GDBN} version 7.7 and earlier, this option was called
27472@code{target-async} instead of @code{mi-async}, and it had the effect
27473of both putting MI in asynchronous mode and making CLI background
27474commands possible. CLI background commands are now always possible
27475``out of the box'' if the target supports them. The old spelling is
27476kept as a deprecated alias for backwards compatibility.
27477
c3b108f7
VP
27478Even if @value{GDBN} can accept a command while target is running,
27479many commands that access the target do not work when the target is
27480running. Therefore, asynchronous command execution is most useful
27481when combined with non-stop mode (@pxref{Non-Stop Mode}). Then,
27482it is possible to examine the state of one thread, while other threads
27483are running.
27484
27485When a given thread is running, MI commands that try to access the
27486target in the context of that thread may not work, or may work only on
27487some targets. In particular, commands that try to operate on thread's
27488stack will not work, on any target. Commands that read memory, or
27489modify breakpoints, may work or not work, depending on the target. Note
27490that even commands that operate on global state, such as @code{print},
27491@code{set}, and breakpoint commands, still access the target in the
27492context of a specific thread, so frontend should try to find a
27493stopped thread and perform the operation on that thread (using the
27494@samp{--thread} option).
27495
27496Which commands will work in the context of a running thread is
27497highly target dependent. However, the two commands
27498@code{-exec-interrupt}, to stop a thread, and @code{-thread-info},
27499to find the state of a thread, will always work.
27500
508094de 27501@node Thread groups
c3b108f7
VP
27502@subsection Thread groups
27503@value{GDBN} may be used to debug several processes at the same time.
27504On some platfroms, @value{GDBN} may support debugging of several
27505hardware systems, each one having several cores with several different
27506processes running on each core. This section describes the MI
27507mechanism to support such debugging scenarios.
27508
27509The key observation is that regardless of the structure of the
27510target, MI can have a global list of threads, because most commands that
27511accept the @samp{--thread} option do not need to know what process that
27512thread belongs to. Therefore, it is not necessary to introduce
27513neither additional @samp{--process} option, nor an notion of the
27514current process in the MI interface. The only strictly new feature
27515that is required is the ability to find how the threads are grouped
27516into processes.
27517
27518To allow the user to discover such grouping, and to support arbitrary
27519hierarchy of machines/cores/processes, MI introduces the concept of a
27520@dfn{thread group}. Thread group is a collection of threads and other
27521thread groups. A thread group always has a string identifier, a type,
27522and may have additional attributes specific to the type. A new
27523command, @code{-list-thread-groups}, returns the list of top-level
27524thread groups, which correspond to processes that @value{GDBN} is
27525debugging at the moment. By passing an identifier of a thread group
27526to the @code{-list-thread-groups} command, it is possible to obtain
27527the members of specific thread group.
27528
27529To allow the user to easily discover processes, and other objects, he
27530wishes to debug, a concept of @dfn{available thread group} is
27531introduced. Available thread group is an thread group that
27532@value{GDBN} is not debugging, but that can be attached to, using the
27533@code{-target-attach} command. The list of available top-level thread
27534groups can be obtained using @samp{-list-thread-groups --available}.
27535In general, the content of a thread group may be only retrieved only
27536after attaching to that thread group.
27537
a79b8f6e
VP
27538Thread groups are related to inferiors (@pxref{Inferiors and
27539Programs}). Each inferior corresponds to a thread group of a special
27540type @samp{process}, and some additional operations are permitted on
27541such thread groups.
27542
922fbb7b
AC
27543@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27544@node GDB/MI Command Syntax
27545@section @sc{gdb/mi} Command Syntax
27546
27547@menu
27548* GDB/MI Input Syntax::
27549* GDB/MI Output Syntax::
922fbb7b
AC
27550@end menu
27551
27552@node GDB/MI Input Syntax
27553@subsection @sc{gdb/mi} Input Syntax
27554
27555@cindex input syntax for @sc{gdb/mi}
27556@cindex @sc{gdb/mi}, input syntax
27557@table @code
27558@item @var{command} @expansion{}
27559@code{@var{cli-command} | @var{mi-command}}
27560
27561@item @var{cli-command} @expansion{}
27562@code{[ @var{token} ] @var{cli-command} @var{nl}}, where
27563@var{cli-command} is any existing @value{GDBN} CLI command.
27564
27565@item @var{mi-command} @expansion{}
27566@code{[ @var{token} ] "-" @var{operation} ( " " @var{option} )*
27567@code{[} " --" @code{]} ( " " @var{parameter} )* @var{nl}}
27568
27569@item @var{token} @expansion{}
27570"any sequence of digits"
27571
27572@item @var{option} @expansion{}
27573@code{"-" @var{parameter} [ " " @var{parameter} ]}
27574
27575@item @var{parameter} @expansion{}
27576@code{@var{non-blank-sequence} | @var{c-string}}
27577
27578@item @var{operation} @expansion{}
27579@emph{any of the operations described in this chapter}
27580
27581@item @var{non-blank-sequence} @expansion{}
27582@emph{anything, provided it doesn't contain special characters such as
27583"-", @var{nl}, """ and of course " "}
27584
27585@item @var{c-string} @expansion{}
27586@code{""" @var{seven-bit-iso-c-string-content} """}
27587
27588@item @var{nl} @expansion{}
27589@code{CR | CR-LF}
27590@end table
27591
27592@noindent
27593Notes:
27594
27595@itemize @bullet
27596@item
27597The CLI commands are still handled by the @sc{mi} interpreter; their
27598output is described below.
27599
27600@item
27601The @code{@var{token}}, when present, is passed back when the command
27602finishes.
27603
27604@item
27605Some @sc{mi} commands accept optional arguments as part of the parameter
27606list. Each option is identified by a leading @samp{-} (dash) and may be
27607followed by an optional argument parameter. Options occur first in the
27608parameter list and can be delimited from normal parameters using
27609@samp{--} (this is useful when some parameters begin with a dash).
27610@end itemize
27611
27612Pragmatics:
27613
27614@itemize @bullet
27615@item
27616We want easy access to the existing CLI syntax (for debugging).
27617
27618@item
27619We want it to be easy to spot a @sc{mi} operation.
27620@end itemize
27621
27622@node GDB/MI Output Syntax
27623@subsection @sc{gdb/mi} Output Syntax
27624
27625@cindex output syntax of @sc{gdb/mi}
27626@cindex @sc{gdb/mi}, output syntax
27627The output from @sc{gdb/mi} consists of zero or more out-of-band records
27628followed, optionally, by a single result record. This result record
27629is for the most recent command. The sequence of output records is
594fe323 27630terminated by @samp{(gdb)}.
922fbb7b
AC
27631
27632If an input command was prefixed with a @code{@var{token}} then the
27633corresponding output for that command will also be prefixed by that same
27634@var{token}.
27635
27636@table @code
27637@item @var{output} @expansion{}
594fe323 27638@code{( @var{out-of-band-record} )* [ @var{result-record} ] "(gdb)" @var{nl}}
922fbb7b
AC
27639
27640@item @var{result-record} @expansion{}
27641@code{ [ @var{token} ] "^" @var{result-class} ( "," @var{result} )* @var{nl}}
27642
27643@item @var{out-of-band-record} @expansion{}
27644@code{@var{async-record} | @var{stream-record}}
27645
27646@item @var{async-record} @expansion{}
27647@code{@var{exec-async-output} | @var{status-async-output} | @var{notify-async-output}}
27648
27649@item @var{exec-async-output} @expansion{}
dcf106f3 27650@code{[ @var{token} ] "*" @var{async-output nl}}
922fbb7b
AC
27651
27652@item @var{status-async-output} @expansion{}
dcf106f3 27653@code{[ @var{token} ] "+" @var{async-output nl}}
922fbb7b
AC
27654
27655@item @var{notify-async-output} @expansion{}
dcf106f3 27656@code{[ @var{token} ] "=" @var{async-output nl}}
922fbb7b
AC
27657
27658@item @var{async-output} @expansion{}
dcf106f3 27659@code{@var{async-class} ( "," @var{result} )*}
922fbb7b
AC
27660
27661@item @var{result-class} @expansion{}
27662@code{"done" | "running" | "connected" | "error" | "exit"}
27663
27664@item @var{async-class} @expansion{}
27665@code{"stopped" | @var{others}} (where @var{others} will be added
27666depending on the needs---this is still in development).
27667
27668@item @var{result} @expansion{}
27669@code{ @var{variable} "=" @var{value}}
27670
27671@item @var{variable} @expansion{}
27672@code{ @var{string} }
27673
27674@item @var{value} @expansion{}
27675@code{ @var{const} | @var{tuple} | @var{list} }
27676
27677@item @var{const} @expansion{}
27678@code{@var{c-string}}
27679
27680@item @var{tuple} @expansion{}
27681@code{ "@{@}" | "@{" @var{result} ( "," @var{result} )* "@}" }
27682
27683@item @var{list} @expansion{}
27684@code{ "[]" | "[" @var{value} ( "," @var{value} )* "]" | "["
27685@var{result} ( "," @var{result} )* "]" }
27686
27687@item @var{stream-record} @expansion{}
27688@code{@var{console-stream-output} | @var{target-stream-output} | @var{log-stream-output}}
27689
27690@item @var{console-stream-output} @expansion{}
dcf106f3 27691@code{"~" @var{c-string nl}}
922fbb7b
AC
27692
27693@item @var{target-stream-output} @expansion{}
dcf106f3 27694@code{"@@" @var{c-string nl}}
922fbb7b
AC
27695
27696@item @var{log-stream-output} @expansion{}
dcf106f3 27697@code{"&" @var{c-string nl}}
922fbb7b
AC
27698
27699@item @var{nl} @expansion{}
27700@code{CR | CR-LF}
27701
27702@item @var{token} @expansion{}
27703@emph{any sequence of digits}.
27704@end table
27705
27706@noindent
27707Notes:
27708
27709@itemize @bullet
27710@item
27711All output sequences end in a single line containing a period.
27712
27713@item
721c02de
VP
27714The @code{@var{token}} is from the corresponding request. Note that
27715for all async output, while the token is allowed by the grammar and
27716may be output by future versions of @value{GDBN} for select async
27717output messages, it is generally omitted. Frontends should treat
27718all async output as reporting general changes in the state of the
27719target and there should be no need to associate async output to any
27720prior command.
922fbb7b
AC
27721
27722@item
27723@cindex status output in @sc{gdb/mi}
27724@var{status-async-output} contains on-going status information about the
27725progress of a slow operation. It can be discarded. All status output is
27726prefixed by @samp{+}.
27727
27728@item
27729@cindex async output in @sc{gdb/mi}
27730@var{exec-async-output} contains asynchronous state change on the target
27731(stopped, started, disappeared). All async output is prefixed by
27732@samp{*}.
27733
27734@item
27735@cindex notify output in @sc{gdb/mi}
27736@var{notify-async-output} contains supplementary information that the
27737client should handle (e.g., a new breakpoint information). All notify
27738output is prefixed by @samp{=}.
27739
27740@item
27741@cindex console output in @sc{gdb/mi}
27742@var{console-stream-output} is output that should be displayed as is in the
27743console. It is the textual response to a CLI command. All the console
27744output is prefixed by @samp{~}.
27745
27746@item
27747@cindex target output in @sc{gdb/mi}
27748@var{target-stream-output} is the output produced by the target program.
27749All the target output is prefixed by @samp{@@}.
27750
27751@item
27752@cindex log output in @sc{gdb/mi}
27753@var{log-stream-output} is output text coming from @value{GDBN}'s internals, for
27754instance messages that should be displayed as part of an error log. All
27755the log output is prefixed by @samp{&}.
27756
27757@item
27758@cindex list output in @sc{gdb/mi}
27759New @sc{gdb/mi} commands should only output @var{lists} containing
27760@var{values}.
27761
27762
27763@end itemize
27764
27765@xref{GDB/MI Stream Records, , @sc{gdb/mi} Stream Records}, for more
27766details about the various output records.
27767
922fbb7b
AC
27768@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27769@node GDB/MI Compatibility with CLI
27770@section @sc{gdb/mi} Compatibility with CLI
27771
27772@cindex compatibility, @sc{gdb/mi} and CLI
27773@cindex @sc{gdb/mi}, compatibility with CLI
922fbb7b 27774
a2c02241
NR
27775For the developers convenience CLI commands can be entered directly,
27776but there may be some unexpected behaviour. For example, commands
27777that query the user will behave as if the user replied yes, breakpoint
27778command lists are not executed and some CLI commands, such as
27779@code{if}, @code{when} and @code{define}, prompt for further input with
27780@samp{>}, which is not valid MI output.
ef21caaf
NR
27781
27782This feature may be removed at some stage in the future and it is
a2c02241
NR
27783recommended that front ends use the @code{-interpreter-exec} command
27784(@pxref{-interpreter-exec}).
922fbb7b 27785
af6eff6f
NR
27786@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27787@node GDB/MI Development and Front Ends
27788@section @sc{gdb/mi} Development and Front Ends
27789@cindex @sc{gdb/mi} development
27790
27791The application which takes the MI output and presents the state of the
27792program being debugged to the user is called a @dfn{front end}.
27793
1fea0d53
SM
27794Since @sc{gdb/mi} is used by a variety of front ends to @value{GDBN}, changes
27795to the MI interface may break existing usage. This section describes how the
27796protocol changes and how to request previous version of the protocol when it
27797does.
af6eff6f
NR
27798
27799Some changes in MI need not break a carefully designed front end, and
27800for these the MI version will remain unchanged. The following is a
27801list of changes that may occur within one level, so front ends should
27802parse MI output in a way that can handle them:
27803
27804@itemize @bullet
27805@item
27806New MI commands may be added.
27807
27808@item
27809New fields may be added to the output of any MI command.
27810
36ece8b3
NR
27811@item
27812The range of values for fields with specified values, e.g.,
9f708cb2 27813@code{in_scope} (@pxref{-var-update}) may be extended.
36ece8b3 27814
af6eff6f
NR
27815@c The format of field's content e.g type prefix, may change so parse it
27816@c at your own risk. Yes, in general?
27817
27818@c The order of fields may change? Shouldn't really matter but it might
27819@c resolve inconsistencies.
27820@end itemize
27821
27822If the changes are likely to break front ends, the MI version level
1fea0d53
SM
27823will be increased by one. The new versions of the MI protocol are not compatible
27824with the old versions. Old versions of MI remain available, allowing front ends
27825to keep using them until they are modified to use the latest MI version.
af6eff6f 27826
1fea0d53
SM
27827Since @code{--interpreter=mi} always points to the latest MI version, it is
27828recommended that front ends request a specific version of MI when launching
27829@value{GDBN} (e.g. @code{--interpreter=mi2}) to make sure they get an
27830interpreter with the MI version they expect.
27831
27832The following table gives a summary of the the released versions of the MI
27833interface: the version number, the version of GDB in which it first appeared
27834and the breaking changes compared to the previous version.
27835
27836@multitable @columnfractions .05 .05 .9
27837@headitem MI version @tab GDB version @tab Breaking changes
27838
27839@item
27840@center 1
27841@tab
27842@center 5.1
27843@tab
27844None
27845
27846@item
27847@center 2
27848@tab
27849@center 6.0
27850@tab
27851
27852@itemize
27853@item
27854The @code{-environment-pwd}, @code{-environment-directory} and
27855@code{-environment-path} commands now returns values using the MI output
27856syntax, rather than CLI output syntax.
27857
27858@item
27859@code{-var-list-children}'s @code{children} result field is now a list, rather
27860than a tuple.
27861
27862@item
27863@code{-var-update}'s @code{changelist} result field is now a list, rather than
27864a tuple.
27865@end itemize
27866
b4be1b06
SM
27867@item
27868@center 3
27869@tab
27870@center 9.1
27871@tab
27872
27873@itemize
27874@item
27875The output of information about multi-location breakpoints has changed in the
27876responses to the @code{-break-insert} and @code{-break-info} commands, as well
27877as in the @code{=breakpoint-created} and @code{=breakpoint-modified} events.
27878The multiple locations are now placed in a @code{locations} field, whose value
27879is a list.
27880@end itemize
27881
1fea0d53 27882@end multitable
af6eff6f 27883
b4be1b06
SM
27884If your front end cannot yet migrate to a more recent version of the
27885MI protocol, you can nevertheless selectively enable specific features
27886available in those recent MI versions, using the following commands:
27887
27888@table @code
27889
27890@item -fix-multi-location-breakpoint-output
27891Use the output for multi-location breakpoints which was introduced by
27892MI 3, even when using MI versions 2 or 1. This command has no
27893effect when using MI version 3 or later.
27894
5c85e20d 27895@end table
b4be1b06 27896
af6eff6f
NR
27897The best way to avoid unexpected changes in MI that might break your front
27898end is to make your project known to @value{GDBN} developers and
7a9a6b69 27899follow development on @email{gdb@@sourceware.org} and
fa0f268d 27900@email{gdb-patches@@sourceware.org}.
af6eff6f
NR
27901@cindex mailing lists
27902
922fbb7b
AC
27903@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27904@node GDB/MI Output Records
27905@section @sc{gdb/mi} Output Records
27906
27907@menu
27908* GDB/MI Result Records::
27909* GDB/MI Stream Records::
82f68b1c 27910* GDB/MI Async Records::
54516a0b 27911* GDB/MI Breakpoint Information::
c3b108f7 27912* GDB/MI Frame Information::
dc146f7c 27913* GDB/MI Thread Information::
4368ebeb 27914* GDB/MI Ada Exception Information::
922fbb7b
AC
27915@end menu
27916
27917@node GDB/MI Result Records
27918@subsection @sc{gdb/mi} Result Records
27919
27920@cindex result records in @sc{gdb/mi}
27921@cindex @sc{gdb/mi}, result records
27922In addition to a number of out-of-band notifications, the response to a
27923@sc{gdb/mi} command includes one of the following result indications:
27924
27925@table @code
27926@findex ^done
27927@item "^done" [ "," @var{results} ]
27928The synchronous operation was successful, @code{@var{results}} are the return
27929values.
27930
27931@item "^running"
27932@findex ^running
8e9c5e02
VP
27933This result record is equivalent to @samp{^done}. Historically, it
27934was output instead of @samp{^done} if the command has resumed the
27935target. This behaviour is maintained for backward compatibility, but
27936all frontends should treat @samp{^done} and @samp{^running}
27937identically and rely on the @samp{*running} output record to determine
27938which threads are resumed.
922fbb7b 27939
ef21caaf
NR
27940@item "^connected"
27941@findex ^connected
3f94c067 27942@value{GDBN} has connected to a remote target.
ef21caaf 27943
2ea126fa 27944@item "^error" "," "msg=" @var{c-string} [ "," "code=" @var{c-string} ]
922fbb7b 27945@findex ^error
2ea126fa
JB
27946The operation failed. The @code{msg=@var{c-string}} variable contains
27947the corresponding error message.
27948
27949If present, the @code{code=@var{c-string}} variable provides an error
27950code on which consumers can rely on to detect the corresponding
27951error condition. At present, only one error code is defined:
27952
27953@table @samp
27954@item "undefined-command"
27955Indicates that the command causing the error does not exist.
27956@end table
ef21caaf
NR
27957
27958@item "^exit"
27959@findex ^exit
3f94c067 27960@value{GDBN} has terminated.
ef21caaf 27961
922fbb7b
AC
27962@end table
27963
27964@node GDB/MI Stream Records
27965@subsection @sc{gdb/mi} Stream Records
27966
27967@cindex @sc{gdb/mi}, stream records
27968@cindex stream records in @sc{gdb/mi}
27969@value{GDBN} internally maintains a number of output streams: the console, the
27970target, and the log. The output intended for each of these streams is
27971funneled through the @sc{gdb/mi} interface using @dfn{stream records}.
27972
27973Each stream record begins with a unique @dfn{prefix character} which
27974identifies its stream (@pxref{GDB/MI Output Syntax, , @sc{gdb/mi} Output
27975Syntax}). In addition to the prefix, each stream record contains a
27976@code{@var{string-output}}. This is either raw text (with an implicit new
27977line) or a quoted C string (which does not contain an implicit newline).
27978
27979@table @code
27980@item "~" @var{string-output}
27981The console output stream contains text that should be displayed in the
27982CLI console window. It contains the textual responses to CLI commands.
27983
27984@item "@@" @var{string-output}
27985The target output stream contains any textual output from the running
ef21caaf
NR
27986target. This is only present when GDB's event loop is truly
27987asynchronous, which is currently only the case for remote targets.
922fbb7b
AC
27988
27989@item "&" @var{string-output}
27990The log stream contains debugging messages being produced by @value{GDBN}'s
27991internals.
27992@end table
27993
82f68b1c
VP
27994@node GDB/MI Async Records
27995@subsection @sc{gdb/mi} Async Records
922fbb7b 27996
82f68b1c
VP
27997@cindex async records in @sc{gdb/mi}
27998@cindex @sc{gdb/mi}, async records
27999@dfn{Async} records are used to notify the @sc{gdb/mi} client of
922fbb7b 28000additional changes that have occurred. Those changes can either be a
82f68b1c 28001consequence of @sc{gdb/mi} commands (e.g., a breakpoint modified) or a result of
922fbb7b
AC
28002target activity (e.g., target stopped).
28003
8eb41542 28004The following is the list of possible async records:
922fbb7b
AC
28005
28006@table @code
034dad6f 28007
e1ac3328 28008@item *running,thread-id="@var{thread}"
5d5658a1
PA
28009The target is now running. The @var{thread} field can be the global
28010thread ID of the the thread that is now running, and it can be
28011@samp{all} if all threads are running. The frontend should assume
28012that no interaction with a running thread is possible after this
28013notification is produced. The frontend should not assume that this
28014notification is output only once for any command. @value{GDBN} may
28015emit this notification several times, either for different threads,
28016because it cannot resume all threads together, or even for a single
28017thread, if the thread must be stepped though some code before letting
28018it run freely.
e1ac3328 28019
dc146f7c 28020@item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}",core="@var{core}"
82f68b1c
VP
28021The target has stopped. The @var{reason} field can have one of the
28022following values:
034dad6f
BR
28023
28024@table @code
28025@item breakpoint-hit
28026A breakpoint was reached.
28027@item watchpoint-trigger
28028A watchpoint was triggered.
28029@item read-watchpoint-trigger
28030A read watchpoint was triggered.
28031@item access-watchpoint-trigger
28032An access watchpoint was triggered.
28033@item function-finished
28034An -exec-finish or similar CLI command was accomplished.
28035@item location-reached
28036An -exec-until or similar CLI command was accomplished.
28037@item watchpoint-scope
28038A watchpoint has gone out of scope.
28039@item end-stepping-range
28040An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or
28041similar CLI command was accomplished.
28042@item exited-signalled
28043The inferior exited because of a signal.
28044@item exited
28045The inferior exited.
28046@item exited-normally
28047The inferior exited normally.
28048@item signal-received
28049A signal was received by the inferior.
36dfb11c
TT
28050@item solib-event
28051The inferior has stopped due to a library being loaded or unloaded.
edcc5120
TT
28052This can happen when @code{stop-on-solib-events} (@pxref{Files}) is
28053set or when a @code{catch load} or @code{catch unload} catchpoint is
28054in use (@pxref{Set Catchpoints}).
36dfb11c
TT
28055@item fork
28056The inferior has forked. This is reported when @code{catch fork}
28057(@pxref{Set Catchpoints}) has been used.
28058@item vfork
28059The inferior has vforked. This is reported in when @code{catch vfork}
28060(@pxref{Set Catchpoints}) has been used.
28061@item syscall-entry
28062The inferior entered a system call. This is reported when @code{catch
28063syscall} (@pxref{Set Catchpoints}) has been used.
a64c9f7b 28064@item syscall-return
36dfb11c
TT
28065The inferior returned from a system call. This is reported when
28066@code{catch syscall} (@pxref{Set Catchpoints}) has been used.
28067@item exec
28068The inferior called @code{exec}. This is reported when @code{catch exec}
28069(@pxref{Set Catchpoints}) has been used.
922fbb7b
AC
28070@end table
28071
5d5658a1
PA
28072The @var{id} field identifies the global thread ID of the thread
28073that directly caused the stop -- for example by hitting a breakpoint.
28074Depending on whether all-stop
c3b108f7
VP
28075mode is in effect (@pxref{All-Stop Mode}), @value{GDBN} may either
28076stop all threads, or only the thread that directly triggered the stop.
28077If all threads are stopped, the @var{stopped} field will have the
28078value of @code{"all"}. Otherwise, the value of the @var{stopped}
28079field will be a list of thread identifiers. Presently, this list will
28080always include a single thread, but frontend should be prepared to see
dc146f7c
VP
28081several threads in the list. The @var{core} field reports the
28082processor core on which the stop event has happened. This field may be absent
28083if such information is not available.
c3b108f7 28084
a79b8f6e
VP
28085@item =thread-group-added,id="@var{id}"
28086@itemx =thread-group-removed,id="@var{id}"
28087A thread group was either added or removed. The @var{id} field
28088contains the @value{GDBN} identifier of the thread group. When a thread
28089group is added, it generally might not be associated with a running
28090process. When a thread group is removed, its id becomes invalid and
28091cannot be used in any way.
28092
28093@item =thread-group-started,id="@var{id}",pid="@var{pid}"
28094A thread group became associated with a running program,
28095either because the program was just started or the thread group
28096was attached to a program. The @var{id} field contains the
28097@value{GDBN} identifier of the thread group. The @var{pid} field
28098contains process identifier, specific to the operating system.
28099
8cf64490 28100@item =thread-group-exited,id="@var{id}"[,exit-code="@var{code}"]
a79b8f6e
VP
28101A thread group is no longer associated with a running program,
28102either because the program has exited, or because it was detached
c3b108f7 28103from. The @var{id} field contains the @value{GDBN} identifier of the
697aa1b7 28104thread group. The @var{code} field is the exit code of the inferior; it exists
8cf64490 28105only when the inferior exited with some code.
c3b108f7
VP
28106
28107@item =thread-created,id="@var{id}",group-id="@var{gid}"
28108@itemx =thread-exited,id="@var{id}",group-id="@var{gid}"
82f68b1c 28109A thread either was created, or has exited. The @var{id} field
5d5658a1 28110contains the global @value{GDBN} identifier of the thread. The @var{gid}
c3b108f7 28111field identifies the thread group this thread belongs to.
66bb093b 28112
4034d0ff
AT
28113@item =thread-selected,id="@var{id}"[,frame="@var{frame}"]
28114Informs that the selected thread or frame were changed. This notification
28115is not emitted as result of the @code{-thread-select} or
28116@code{-stack-select-frame} commands, but is emitted whenever an MI command
28117that is not documented to change the selected thread and frame actually
28118changes them. In particular, invoking, directly or indirectly
28119(via user-defined command), the CLI @code{thread} or @code{frame} commands,
28120will generate this notification. Changing the thread or frame from another
28121user interface (see @ref{Interpreters}) will also generate this notification.
28122
28123The @var{frame} field is only present if the newly selected thread is
28124stopped. See @ref{GDB/MI Frame Information} for the format of its value.
66bb093b
VP
28125
28126We suggest that in response to this notification, front ends
28127highlight the selected thread and cause subsequent commands to apply to
28128that thread.
28129
c86cf029
VP
28130@item =library-loaded,...
28131Reports that a new library file was loaded by the program. This
51457a05
MAL
28132notification has 5 fields---@var{id}, @var{target-name},
28133@var{host-name}, @var{symbols-loaded} and @var{ranges}. The @var{id} field is an
c86cf029
VP
28134opaque identifier of the library. For remote debugging case,
28135@var{target-name} and @var{host-name} fields give the name of the
134eb42c
VP
28136library file on the target, and on the host respectively. For native
28137debugging, both those fields have the same value. The
f1cbe1d3
TT
28138@var{symbols-loaded} field is emitted only for backward compatibility
28139and should not be relied on to convey any useful information. The
28140@var{thread-group} field, if present, specifies the id of the thread
28141group in whose context the library was loaded. If the field is
28142absent, it means the library was loaded in the context of all present
51457a05
MAL
28143thread groups. The @var{ranges} field specifies the ranges of addresses belonging
28144to this library.
c86cf029
VP
28145
28146@item =library-unloaded,...
134eb42c 28147Reports that a library was unloaded by the program. This notification
c86cf029 28148has 3 fields---@var{id}, @var{target-name} and @var{host-name} with
a79b8f6e
VP
28149the same meaning as for the @code{=library-loaded} notification.
28150The @var{thread-group} field, if present, specifies the id of the
28151thread group in whose context the library was unloaded. If the field is
28152absent, it means the library was unloaded in the context of all present
28153thread groups.
c86cf029 28154
201b4506
YQ
28155@item =traceframe-changed,num=@var{tfnum},tracepoint=@var{tpnum}
28156@itemx =traceframe-changed,end
28157Reports that the trace frame was changed and its new number is
28158@var{tfnum}. The number of the tracepoint associated with this trace
28159frame is @var{tpnum}.
28160
134a2066 28161@item =tsv-created,name=@var{name},initial=@var{initial}
bb25a15c 28162Reports that the new trace state variable @var{name} is created with
134a2066 28163initial value @var{initial}.
bb25a15c
YQ
28164
28165@item =tsv-deleted,name=@var{name}
28166@itemx =tsv-deleted
28167Reports that the trace state variable @var{name} is deleted or all
28168trace state variables are deleted.
28169
134a2066
YQ
28170@item =tsv-modified,name=@var{name},initial=@var{initial}[,current=@var{current}]
28171Reports that the trace state variable @var{name} is modified with
28172the initial value @var{initial}. The current value @var{current} of
28173trace state variable is optional and is reported if the current
28174value of trace state variable is known.
28175
8d3788bd
VP
28176@item =breakpoint-created,bkpt=@{...@}
28177@itemx =breakpoint-modified,bkpt=@{...@}
d9f08f52 28178@itemx =breakpoint-deleted,id=@var{number}
8d3788bd
VP
28179Reports that a breakpoint was created, modified, or deleted,
28180respectively. Only user-visible breakpoints are reported to the MI
28181user.
28182
28183The @var{bkpt} argument is of the same form as returned by the various
d9f08f52
YQ
28184breakpoint commands; @xref{GDB/MI Breakpoint Commands}. The
28185@var{number} is the ordinal number of the breakpoint.
8d3788bd
VP
28186
28187Note that if a breakpoint is emitted in the result record of a
28188command, then it will not also be emitted in an async record.
28189
38b022b4 28190@item =record-started,thread-group="@var{id}",method="@var{method}"[,format="@var{format}"]
82a90ccf
YQ
28191@itemx =record-stopped,thread-group="@var{id}"
28192Execution log recording was either started or stopped on an
28193inferior. The @var{id} is the @value{GDBN} identifier of the thread
28194group corresponding to the affected inferior.
28195
38b022b4
SM
28196The @var{method} field indicates the method used to record execution. If the
28197method in use supports multiple recording formats, @var{format} will be present
8504e097 28198and contain the currently used format. @xref{Process Record and Replay},
38b022b4
SM
28199for existing method and format values.
28200
5b9afe8a
YQ
28201@item =cmd-param-changed,param=@var{param},value=@var{value}
28202Reports that a parameter of the command @code{set @var{param}} is
28203changed to @var{value}. In the multi-word @code{set} command,
28204the @var{param} is the whole parameter list to @code{set} command.
28205For example, In command @code{set check type on}, @var{param}
28206is @code{check type} and @var{value} is @code{on}.
8de0566d
YQ
28207
28208@item =memory-changed,thread-group=@var{id},addr=@var{addr},len=@var{len}[,type="code"]
28209Reports that bytes from @var{addr} to @var{data} + @var{len} were
28210written in an inferior. The @var{id} is the identifier of the
28211thread group corresponding to the affected inferior. The optional
28212@code{type="code"} part is reported if the memory written to holds
28213executable code.
82f68b1c
VP
28214@end table
28215
54516a0b
TT
28216@node GDB/MI Breakpoint Information
28217@subsection @sc{gdb/mi} Breakpoint Information
28218
28219When @value{GDBN} reports information about a breakpoint, a
28220tracepoint, a watchpoint, or a catchpoint, it uses a tuple with the
28221following fields:
28222
28223@table @code
28224@item number
b4be1b06 28225The breakpoint number.
54516a0b
TT
28226
28227@item type
28228The type of the breakpoint. For ordinary breakpoints this will be
28229@samp{breakpoint}, but many values are possible.
28230
8ac3646f
TT
28231@item catch-type
28232If the type of the breakpoint is @samp{catchpoint}, then this
28233indicates the exact type of catchpoint.
28234
54516a0b
TT
28235@item disp
28236This is the breakpoint disposition---either @samp{del}, meaning that
28237the breakpoint will be deleted at the next stop, or @samp{keep},
28238meaning that the breakpoint will not be deleted.
28239
28240@item enabled
28241This indicates whether the breakpoint is enabled, in which case the
28242value is @samp{y}, or disabled, in which case the value is @samp{n}.
28243Note that this is not the same as the field @code{enable}.
28244
28245@item addr
28246The address of the breakpoint. This may be a hexidecimal number,
28247giving the address; or the string @samp{<PENDING>}, for a pending
28248breakpoint; or the string @samp{<MULTIPLE>}, for a breakpoint with
28249multiple locations. This field will not be present if no address can
28250be determined. For example, a watchpoint does not have an address.
28251
28252@item func
28253If known, the function in which the breakpoint appears.
28254If not known, this field is not present.
28255
28256@item filename
28257The name of the source file which contains this function, if known.
28258If not known, this field is not present.
28259
28260@item fullname
28261The full file name of the source file which contains this function, if
28262known. If not known, this field is not present.
28263
28264@item line
28265The line number at which this breakpoint appears, if known.
28266If not known, this field is not present.
28267
28268@item at
28269If the source file is not known, this field may be provided. If
28270provided, this holds the address of the breakpoint, possibly followed
28271by a symbol name.
28272
28273@item pending
28274If this breakpoint is pending, this field is present and holds the
28275text used to set the breakpoint, as entered by the user.
28276
28277@item evaluated-by
28278Where this breakpoint's condition is evaluated, either @samp{host} or
28279@samp{target}.
28280
28281@item thread
28282If this is a thread-specific breakpoint, then this identifies the
28283thread in which the breakpoint can trigger.
28284
28285@item task
28286If this breakpoint is restricted to a particular Ada task, then this
28287field will hold the task identifier.
28288
28289@item cond
28290If the breakpoint is conditional, this is the condition expression.
28291
28292@item ignore
28293The ignore count of the breakpoint.
28294
28295@item enable
28296The enable count of the breakpoint.
28297
28298@item traceframe-usage
28299FIXME.
28300
28301@item static-tracepoint-marker-string-id
28302For a static tracepoint, the name of the static tracepoint marker.
28303
28304@item mask
28305For a masked watchpoint, this is the mask.
28306
28307@item pass
28308A tracepoint's pass count.
28309
28310@item original-location
28311The location of the breakpoint as originally specified by the user.
28312This field is optional.
28313
28314@item times
28315The number of times the breakpoint has been hit.
28316
28317@item installed
28318This field is only given for tracepoints. This is either @samp{y},
28319meaning that the tracepoint is installed, or @samp{n}, meaning that it
28320is not.
28321
28322@item what
28323Some extra data, the exact contents of which are type-dependent.
28324
b4be1b06
SM
28325@item locations
28326This field is present if the breakpoint has multiple locations. It is also
28327exceptionally present if the breakpoint is enabled and has a single, disabled
28328location.
28329
28330The value is a list of locations. The format of a location is decribed below.
28331
28332@end table
28333
28334A location in a multi-location breakpoint is represented as a tuple with the
28335following fields:
28336
28337@table @code
28338
28339@item number
28340The location number as a dotted pair, like @samp{1.2}. The first digit is the
28341number of the parent breakpoint. The second digit is the number of the
28342location within that breakpoint.
28343
28344@item enabled
28345This indicates whether the location is enabled, in which case the
28346value is @samp{y}, or disabled, in which case the value is @samp{n}.
28347Note that this is not the same as the field @code{enable}.
28348
28349@item addr
28350The address of this location as an hexidecimal number.
28351
28352@item func
28353If known, the function in which the location appears.
28354If not known, this field is not present.
28355
28356@item file
28357The name of the source file which contains this location, if known.
28358If not known, this field is not present.
28359
28360@item fullname
28361The full file name of the source file which contains this location, if
28362known. If not known, this field is not present.
28363
28364@item line
28365The line number at which this location appears, if known.
28366If not known, this field is not present.
28367
28368@item thread-groups
28369The thread groups this location is in.
28370
54516a0b
TT
28371@end table
28372
28373For example, here is what the output of @code{-break-insert}
28374(@pxref{GDB/MI Breakpoint Commands}) might be:
28375
28376@smallexample
28377-> -break-insert main
28378<- ^done,bkpt=@{number="1",type="breakpoint",disp="keep",
28379 enabled="y",addr="0x08048564",func="main",file="myprog.c",
998580f1
MK
28380 fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"],
28381 times="0"@}
54516a0b
TT
28382<- (gdb)
28383@end smallexample
28384
c3b108f7
VP
28385@node GDB/MI Frame Information
28386@subsection @sc{gdb/mi} Frame Information
28387
28388Response from many MI commands includes an information about stack
28389frame. This information is a tuple that may have the following
28390fields:
28391
28392@table @code
28393@item level
28394The level of the stack frame. The innermost frame has the level of
28395zero. This field is always present.
28396
28397@item func
28398The name of the function corresponding to the frame. This field may
28399be absent if @value{GDBN} is unable to determine the function name.
28400
28401@item addr
28402The code address for the frame. This field is always present.
28403
28404@item file
28405The name of the source files that correspond to the frame's code
28406address. This field may be absent.
28407
28408@item line
28409The source line corresponding to the frames' code address. This field
28410may be absent.
28411
28412@item from
28413The name of the binary file (either executable or shared library) the
28414corresponds to the frame's code address. This field may be absent.
28415
28416@end table
82f68b1c 28417
dc146f7c
VP
28418@node GDB/MI Thread Information
28419@subsection @sc{gdb/mi} Thread Information
28420
28421Whenever @value{GDBN} has to report an information about a thread, it
ebe553db
SM
28422uses a tuple with the following fields. The fields are always present unless
28423stated otherwise.
dc146f7c
VP
28424
28425@table @code
28426@item id
ebe553db 28427The global numeric id assigned to the thread by @value{GDBN}.
dc146f7c
VP
28428
28429@item target-id
ebe553db 28430The target-specific string identifying the thread.
dc146f7c
VP
28431
28432@item details
28433Additional information about the thread provided by the target.
28434It is supposed to be human-readable and not interpreted by the
28435frontend. This field is optional.
28436
ebe553db
SM
28437@item name
28438The name of the thread. If the user specified a name using the
28439@code{thread name} command, then this name is given. Otherwise, if
28440@value{GDBN} can extract the thread name from the target, then that
28441name is given. If @value{GDBN} cannot find the thread name, then this
28442field is omitted.
28443
dc146f7c 28444@item state
ebe553db
SM
28445The execution state of the thread, either @samp{stopped} or @samp{running},
28446depending on whether the thread is presently running.
28447
28448@item frame
28449The stack frame currently executing in the thread. This field is only present
28450if the thread is stopped. Its format is documented in
28451@ref{GDB/MI Frame Information}.
dc146f7c
VP
28452
28453@item core
28454The value of this field is an integer number of the processor core the
28455thread was last seen on. This field is optional.
28456@end table
28457
956a9fb9
JB
28458@node GDB/MI Ada Exception Information
28459@subsection @sc{gdb/mi} Ada Exception Information
28460
28461Whenever a @code{*stopped} record is emitted because the program
28462stopped after hitting an exception catchpoint (@pxref{Set Catchpoints}),
28463@value{GDBN} provides the name of the exception that was raised via
e547c119
JB
28464the @code{exception-name} field. Also, for exceptions that were raised
28465with an exception message, @value{GDBN} provides that message via
28466the @code{exception-message} field.
922fbb7b 28467
ef21caaf
NR
28468@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
28469@node GDB/MI Simple Examples
28470@section Simple Examples of @sc{gdb/mi} Interaction
28471@cindex @sc{gdb/mi}, simple examples
28472
28473This subsection presents several simple examples of interaction using
28474the @sc{gdb/mi} interface. In these examples, @samp{->} means that the
28475following line is passed to @sc{gdb/mi} as input, while @samp{<-} means
28476the output received from @sc{gdb/mi}.
28477
d3e8051b 28478Note the line breaks shown in the examples are here only for
ef21caaf
NR
28479readability, they don't appear in the real output.
28480
79a6e687 28481@subheading Setting a Breakpoint
ef21caaf
NR
28482
28483Setting a breakpoint generates synchronous output which contains detailed
28484information of the breakpoint.
28485
28486@smallexample
28487-> -break-insert main
28488<- ^done,bkpt=@{number="1",type="breakpoint",disp="keep",
28489 enabled="y",addr="0x08048564",func="main",file="myprog.c",
998580f1
MK
28490 fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"],
28491 times="0"@}
ef21caaf
NR
28492<- (gdb)
28493@end smallexample
28494
28495@subheading Program Execution
28496
28497Program execution generates asynchronous records and MI gives the
28498reason that execution stopped.
28499
28500@smallexample
28501-> -exec-run
28502<- ^running
28503<- (gdb)
a47ec5fe 28504<- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
ef21caaf
NR
28505 frame=@{addr="0x08048564",func="main",
28506 args=[@{name="argc",value="1"@},@{name="argv",value="0xbfc4d4d4"@}],
6d52907e
JV
28507 file="myprog.c",fullname="/home/nickrob/myprog.c",line="68",
28508 arch="i386:x86_64"@}
ef21caaf
NR
28509<- (gdb)
28510-> -exec-continue
28511<- ^running
28512<- (gdb)
28513<- *stopped,reason="exited-normally"
28514<- (gdb)
28515@end smallexample
28516
3f94c067 28517@subheading Quitting @value{GDBN}
ef21caaf 28518
3f94c067 28519Quitting @value{GDBN} just prints the result class @samp{^exit}.
ef21caaf
NR
28520
28521@smallexample
28522-> (gdb)
28523<- -gdb-exit
28524<- ^exit
28525@end smallexample
28526
a6b29f87
VP
28527Please note that @samp{^exit} is printed immediately, but it might
28528take some time for @value{GDBN} to actually exit. During that time, @value{GDBN}
28529performs necessary cleanups, including killing programs being debugged
28530or disconnecting from debug hardware, so the frontend should wait till
28531@value{GDBN} exits and should only forcibly kill @value{GDBN} if it
28532fails to exit in reasonable time.
28533
a2c02241 28534@subheading A Bad Command
ef21caaf
NR
28535
28536Here's what happens if you pass a non-existent command:
28537
28538@smallexample
28539-> -rubbish
28540<- ^error,msg="Undefined MI command: rubbish"
594fe323 28541<- (gdb)
ef21caaf
NR
28542@end smallexample
28543
28544
922fbb7b
AC
28545@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
28546@node GDB/MI Command Description Format
28547@section @sc{gdb/mi} Command Description Format
28548
28549The remaining sections describe blocks of commands. Each block of
28550commands is laid out in a fashion similar to this section.
28551
922fbb7b
AC
28552@subheading Motivation
28553
28554The motivation for this collection of commands.
28555
28556@subheading Introduction
28557
28558A brief introduction to this collection of commands as a whole.
28559
28560@subheading Commands
28561
28562For each command in the block, the following is described:
28563
28564@subsubheading Synopsis
28565
28566@smallexample
28567 -command @var{args}@dots{}
28568@end smallexample
28569
922fbb7b
AC
28570@subsubheading Result
28571
265eeb58 28572@subsubheading @value{GDBN} Command
922fbb7b 28573
265eeb58 28574The corresponding @value{GDBN} CLI command(s), if any.
922fbb7b
AC
28575
28576@subsubheading Example
28577
ef21caaf
NR
28578Example(s) formatted for readability. Some of the described commands have
28579not been implemented yet and these are labeled N.A.@: (not available).
28580
28581
922fbb7b 28582@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
ef21caaf
NR
28583@node GDB/MI Breakpoint Commands
28584@section @sc{gdb/mi} Breakpoint Commands
922fbb7b
AC
28585
28586@cindex breakpoint commands for @sc{gdb/mi}
28587@cindex @sc{gdb/mi}, breakpoint commands
28588This section documents @sc{gdb/mi} commands for manipulating
28589breakpoints.
28590
28591@subheading The @code{-break-after} Command
28592@findex -break-after
28593
28594@subsubheading Synopsis
28595
28596@smallexample
28597 -break-after @var{number} @var{count}
28598@end smallexample
28599
28600The breakpoint number @var{number} is not in effect until it has been
28601hit @var{count} times. To see how this is reflected in the output of
28602the @samp{-break-list} command, see the description of the
28603@samp{-break-list} command below.
28604
28605@subsubheading @value{GDBN} Command
28606
28607The corresponding @value{GDBN} command is @samp{ignore}.
28608
28609@subsubheading Example
28610
28611@smallexample
594fe323 28612(gdb)
922fbb7b 28613-break-insert main
a47ec5fe
AR
28614^done,bkpt=@{number="1",type="breakpoint",disp="keep",
28615enabled="y",addr="0x000100d0",func="main",file="hello.c",
998580f1
MK
28616fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
28617times="0"@}
594fe323 28618(gdb)
922fbb7b
AC
28619-break-after 1 3
28620~
28621^done
594fe323 28622(gdb)
922fbb7b
AC
28623-break-list
28624^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
28625hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28626@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28627@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28628@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28629@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28630@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28631body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
948d5102 28632addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
998580f1 28633line="5",thread-groups=["i1"],times="0",ignore="3"@}]@}
594fe323 28634(gdb)
922fbb7b
AC
28635@end smallexample
28636
28637@ignore
28638@subheading The @code{-break-catch} Command
28639@findex -break-catch
48cb2d85 28640@end ignore
922fbb7b
AC
28641
28642@subheading The @code{-break-commands} Command
28643@findex -break-commands
922fbb7b 28644
48cb2d85
VP
28645@subsubheading Synopsis
28646
28647@smallexample
28648 -break-commands @var{number} [ @var{command1} ... @var{commandN} ]
28649@end smallexample
28650
28651Specifies the CLI commands that should be executed when breakpoint
28652@var{number} is hit. The parameters @var{command1} to @var{commandN}
28653are the commands. If no command is specified, any previously-set
28654commands are cleared. @xref{Break Commands}. Typical use of this
28655functionality is tracing a program, that is, printing of values of
28656some variables whenever breakpoint is hit and then continuing.
28657
28658@subsubheading @value{GDBN} Command
28659
28660The corresponding @value{GDBN} command is @samp{commands}.
28661
28662@subsubheading Example
28663
28664@smallexample
28665(gdb)
28666-break-insert main
28667^done,bkpt=@{number="1",type="breakpoint",disp="keep",
28668enabled="y",addr="0x000100d0",func="main",file="hello.c",
998580f1
MK
28669fullname="/home/foo/hello.c",line="5",thread-groups=["i1"],
28670times="0"@}
48cb2d85
VP
28671(gdb)
28672-break-commands 1 "print v" "continue"
28673^done
28674(gdb)
28675@end smallexample
922fbb7b
AC
28676
28677@subheading The @code{-break-condition} Command
28678@findex -break-condition
28679
28680@subsubheading Synopsis
28681
28682@smallexample
28683 -break-condition @var{number} @var{expr}
28684@end smallexample
28685
28686Breakpoint @var{number} will stop the program only if the condition in
28687@var{expr} is true. The condition becomes part of the
28688@samp{-break-list} output (see the description of the @samp{-break-list}
28689command below).
28690
28691@subsubheading @value{GDBN} Command
28692
28693The corresponding @value{GDBN} command is @samp{condition}.
28694
28695@subsubheading Example
28696
28697@smallexample
594fe323 28698(gdb)
922fbb7b
AC
28699-break-condition 1 1
28700^done
594fe323 28701(gdb)
922fbb7b
AC
28702-break-list
28703^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
28704hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28705@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28706@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28707@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28708@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28709@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28710body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
948d5102 28711addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
998580f1 28712line="5",cond="1",thread-groups=["i1"],times="0",ignore="3"@}]@}
594fe323 28713(gdb)
922fbb7b
AC
28714@end smallexample
28715
28716@subheading The @code{-break-delete} Command
28717@findex -break-delete
28718
28719@subsubheading Synopsis
28720
28721@smallexample
28722 -break-delete ( @var{breakpoint} )+
28723@end smallexample
28724
28725Delete the breakpoint(s) whose number(s) are specified in the argument
28726list. This is obviously reflected in the breakpoint list.
28727
79a6e687 28728@subsubheading @value{GDBN} Command
922fbb7b
AC
28729
28730The corresponding @value{GDBN} command is @samp{delete}.
28731
28732@subsubheading Example
28733
28734@smallexample
594fe323 28735(gdb)
922fbb7b
AC
28736-break-delete 1
28737^done
594fe323 28738(gdb)
922fbb7b
AC
28739-break-list
28740^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
28741hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28742@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28743@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28744@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28745@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28746@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28747body=[]@}
594fe323 28748(gdb)
922fbb7b
AC
28749@end smallexample
28750
28751@subheading The @code{-break-disable} Command
28752@findex -break-disable
28753
28754@subsubheading Synopsis
28755
28756@smallexample
28757 -break-disable ( @var{breakpoint} )+
28758@end smallexample
28759
28760Disable the named @var{breakpoint}(s). The field @samp{enabled} in the
28761break list is now set to @samp{n} for the named @var{breakpoint}(s).
28762
28763@subsubheading @value{GDBN} Command
28764
28765The corresponding @value{GDBN} command is @samp{disable}.
28766
28767@subsubheading Example
28768
28769@smallexample
594fe323 28770(gdb)
922fbb7b
AC
28771-break-disable 2
28772^done
594fe323 28773(gdb)
922fbb7b
AC
28774-break-list
28775^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
28776hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28777@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28778@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28779@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28780@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28781@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28782body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="n",
948d5102 28783addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
998580f1 28784line="5",thread-groups=["i1"],times="0"@}]@}
594fe323 28785(gdb)
922fbb7b
AC
28786@end smallexample
28787
28788@subheading The @code{-break-enable} Command
28789@findex -break-enable
28790
28791@subsubheading Synopsis
28792
28793@smallexample
28794 -break-enable ( @var{breakpoint} )+
28795@end smallexample
28796
28797Enable (previously disabled) @var{breakpoint}(s).
28798
28799@subsubheading @value{GDBN} Command
28800
28801The corresponding @value{GDBN} command is @samp{enable}.
28802
28803@subsubheading Example
28804
28805@smallexample
594fe323 28806(gdb)
922fbb7b
AC
28807-break-enable 2
28808^done
594fe323 28809(gdb)
922fbb7b
AC
28810-break-list
28811^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
28812hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28813@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28814@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28815@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28816@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28817@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28818body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
948d5102 28819addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
998580f1 28820line="5",thread-groups=["i1"],times="0"@}]@}
594fe323 28821(gdb)
922fbb7b
AC
28822@end smallexample
28823
28824@subheading The @code{-break-info} Command
28825@findex -break-info
28826
28827@subsubheading Synopsis
28828
28829@smallexample
28830 -break-info @var{breakpoint}
28831@end smallexample
28832
28833@c REDUNDANT???
28834Get information about a single breakpoint.
28835
54516a0b
TT
28836The result is a table of breakpoints. @xref{GDB/MI Breakpoint
28837Information}, for details on the format of each breakpoint in the
28838table.
28839
79a6e687 28840@subsubheading @value{GDBN} Command
922fbb7b
AC
28841
28842The corresponding @value{GDBN} command is @samp{info break @var{breakpoint}}.
28843
28844@subsubheading Example
28845N.A.
28846
28847@subheading The @code{-break-insert} Command
28848@findex -break-insert
629500fa 28849@anchor{-break-insert}
922fbb7b
AC
28850
28851@subsubheading Synopsis
28852
28853@smallexample
18148017 28854 -break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ]
922fbb7b 28855 [ -c @var{condition} ] [ -i @var{ignore-count} ]
472a2379 28856 [ -p @var{thread-id} ] [ @var{location} ]
922fbb7b
AC
28857@end smallexample
28858
28859@noindent
afe8ab22 28860If specified, @var{location}, can be one of:
922fbb7b 28861
629500fa
KS
28862@table @var
28863@item linespec location
28864A linespec location. @xref{Linespec Locations}.
28865
28866@item explicit location
28867An explicit location. @sc{gdb/mi} explicit locations are
28868analogous to the CLI's explicit locations using the option names
28869listed below. @xref{Explicit Locations}.
28870
28871@table @samp
28872@item --source @var{filename}
28873The source file name of the location. This option requires the use
28874of either @samp{--function} or @samp{--line}.
28875
28876@item --function @var{function}
28877The name of a function or method.
922fbb7b 28878
629500fa
KS
28879@item --label @var{label}
28880The name of a label.
28881
28882@item --line @var{lineoffset}
28883An absolute or relative line offset from the start of the location.
28884@end table
28885
28886@item address location
28887An address location, *@var{address}. @xref{Address Locations}.
28888@end table
28889
28890@noindent
922fbb7b
AC
28891The possible optional parameters of this command are:
28892
28893@table @samp
28894@item -t
948d5102 28895Insert a temporary breakpoint.
922fbb7b
AC
28896@item -h
28897Insert a hardware breakpoint.
afe8ab22
VP
28898@item -f
28899If @var{location} cannot be parsed (for example if it
28900refers to unknown files or functions), create a pending
28901breakpoint. Without this flag, @value{GDBN} will report
28902an error, and won't create a breakpoint, if @var{location}
28903cannot be parsed.
41447f92
VP
28904@item -d
28905Create a disabled breakpoint.
18148017
VP
28906@item -a
28907Create a tracepoint. @xref{Tracepoints}. When this parameter
28908is used together with @samp{-h}, a fast tracepoint is created.
472a2379
KS
28909@item -c @var{condition}
28910Make the breakpoint conditional on @var{condition}.
28911@item -i @var{ignore-count}
28912Initialize the @var{ignore-count}.
28913@item -p @var{thread-id}
5d5658a1
PA
28914Restrict the breakpoint to the thread with the specified global
28915@var{thread-id}.
922fbb7b
AC
28916@end table
28917
28918@subsubheading Result
28919
54516a0b
TT
28920@xref{GDB/MI Breakpoint Information}, for details on the format of the
28921resulting breakpoint.
922fbb7b
AC
28922
28923Note: this format is open to change.
28924@c An out-of-band breakpoint instead of part of the result?
28925
28926@subsubheading @value{GDBN} Command
28927
28928The corresponding @value{GDBN} commands are @samp{break}, @samp{tbreak},
496ee73e 28929@samp{hbreak}, and @samp{thbreak}. @c and @samp{rbreak}.
922fbb7b
AC
28930
28931@subsubheading Example
28932
28933@smallexample
594fe323 28934(gdb)
922fbb7b 28935-break-insert main
948d5102 28936^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",
998580f1
MK
28937fullname="/home/foo/recursive2.c,line="4",thread-groups=["i1"],
28938times="0"@}
594fe323 28939(gdb)
922fbb7b 28940-break-insert -t foo
948d5102 28941^done,bkpt=@{number="2",addr="0x00010774",file="recursive2.c",
998580f1
MK
28942fullname="/home/foo/recursive2.c,line="11",thread-groups=["i1"],
28943times="0"@}
594fe323 28944(gdb)
922fbb7b
AC
28945-break-list
28946^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
28947hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
28948@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
28949@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
28950@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
28951@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
28952@{width="40",alignment="2",col_name="what",colhdr="What"@}],
28953body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
948d5102 28954addr="0x0001072c", func="main",file="recursive2.c",
998580f1
MK
28955fullname="/home/foo/recursive2.c,"line="4",thread-groups=["i1"],
28956times="0"@},
922fbb7b 28957bkpt=@{number="2",type="breakpoint",disp="del",enabled="y",
948d5102 28958addr="0x00010774",func="foo",file="recursive2.c",
998580f1
MK
28959fullname="/home/foo/recursive2.c",line="11",thread-groups=["i1"],
28960times="0"@}]@}
594fe323 28961(gdb)
496ee73e
KS
28962@c -break-insert -r foo.*
28963@c ~int foo(int, int);
28964@c ^done,bkpt=@{number="3",addr="0x00010774",file="recursive2.c,
998580f1
MK
28965@c "fullname="/home/foo/recursive2.c",line="11",thread-groups=["i1"],
28966@c times="0"@}
496ee73e 28967@c (gdb)
922fbb7b
AC
28968@end smallexample
28969
c5867ab6
HZ
28970@subheading The @code{-dprintf-insert} Command
28971@findex -dprintf-insert
28972
28973@subsubheading Synopsis
28974
28975@smallexample
28976 -dprintf-insert [ -t ] [ -f ] [ -d ]
28977 [ -c @var{condition} ] [ -i @var{ignore-count} ]
28978 [ -p @var{thread-id} ] [ @var{location} ] [ @var{format} ]
28979 [ @var{argument} ]
28980@end smallexample
28981
28982@noindent
629500fa
KS
28983If supplied, @var{location} may be specified the same way as for
28984the @code{-break-insert} command. @xref{-break-insert}.
c5867ab6
HZ
28985
28986The possible optional parameters of this command are:
28987
28988@table @samp
28989@item -t
28990Insert a temporary breakpoint.
28991@item -f
28992If @var{location} cannot be parsed (for example, if it
28993refers to unknown files or functions), create a pending
28994breakpoint. Without this flag, @value{GDBN} will report
28995an error, and won't create a breakpoint, if @var{location}
28996cannot be parsed.
28997@item -d
28998Create a disabled breakpoint.
28999@item -c @var{condition}
29000Make the breakpoint conditional on @var{condition}.
29001@item -i @var{ignore-count}
29002Set the ignore count of the breakpoint (@pxref{Conditions, ignore count})
29003to @var{ignore-count}.
29004@item -p @var{thread-id}
5d5658a1
PA
29005Restrict the breakpoint to the thread with the specified global
29006@var{thread-id}.
c5867ab6
HZ
29007@end table
29008
29009@subsubheading Result
29010
29011@xref{GDB/MI Breakpoint Information}, for details on the format of the
29012resulting breakpoint.
29013
29014@c An out-of-band breakpoint instead of part of the result?
29015
29016@subsubheading @value{GDBN} Command
29017
29018The corresponding @value{GDBN} command is @samp{dprintf}.
29019
29020@subsubheading Example
29021
29022@smallexample
29023(gdb)
290244-dprintf-insert foo "At foo entry\n"
290254^done,bkpt=@{number="1",type="dprintf",disp="keep",enabled="y",
29026addr="0x000000000040061b",func="foo",file="mi-dprintf.c",
29027fullname="mi-dprintf.c",line="25",thread-groups=["i1"],
29028times="0",script=@{"printf \"At foo entry\\n\"","continue"@},
29029original-location="foo"@}
29030(gdb)
290315-dprintf-insert 26 "arg=%d, g=%d\n" arg g
290325^done,bkpt=@{number="2",type="dprintf",disp="keep",enabled="y",
29033addr="0x000000000040062a",func="foo",file="mi-dprintf.c",
29034fullname="mi-dprintf.c",line="26",thread-groups=["i1"],
29035times="0",script=@{"printf \"arg=%d, g=%d\\n\", arg, g","continue"@},
29036original-location="mi-dprintf.c:26"@}
29037(gdb)
29038@end smallexample
29039
922fbb7b
AC
29040@subheading The @code{-break-list} Command
29041@findex -break-list
29042
29043@subsubheading Synopsis
29044
29045@smallexample
29046 -break-list
29047@end smallexample
29048
29049Displays the list of inserted breakpoints, showing the following fields:
29050
29051@table @samp
29052@item Number
29053number of the breakpoint
29054@item Type
29055type of the breakpoint: @samp{breakpoint} or @samp{watchpoint}
29056@item Disposition
29057should the breakpoint be deleted or disabled when it is hit: @samp{keep}
29058or @samp{nokeep}
29059@item Enabled
29060is the breakpoint enabled or no: @samp{y} or @samp{n}
29061@item Address
29062memory location at which the breakpoint is set
29063@item What
29064logical location of the breakpoint, expressed by function name, file
29065name, line number
998580f1
MK
29066@item Thread-groups
29067list of thread groups to which this breakpoint applies
922fbb7b
AC
29068@item Times
29069number of times the breakpoint has been hit
29070@end table
29071
29072If there are no breakpoints or watchpoints, the @code{BreakpointTable}
29073@code{body} field is an empty list.
29074
29075@subsubheading @value{GDBN} Command
29076
29077The corresponding @value{GDBN} command is @samp{info break}.
29078
29079@subsubheading Example
29080
29081@smallexample
594fe323 29082(gdb)
922fbb7b
AC
29083-break-list
29084^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
29085hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
29086@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
29087@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
29088@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
29089@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
29090@{width="40",alignment="2",col_name="what",colhdr="What"@}],
29091body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
998580f1
MK
29092addr="0x000100d0",func="main",file="hello.c",line="5",thread-groups=["i1"],
29093times="0"@},
922fbb7b 29094bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
948d5102 29095addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c",
998580f1 29096line="13",thread-groups=["i1"],times="0"@}]@}
594fe323 29097(gdb)
922fbb7b
AC
29098@end smallexample
29099
29100Here's an example of the result when there are no breakpoints:
29101
29102@smallexample
594fe323 29103(gdb)
922fbb7b
AC
29104-break-list
29105^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
29106hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
29107@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
29108@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
29109@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
29110@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
29111@{width="40",alignment="2",col_name="what",colhdr="What"@}],
29112body=[]@}
594fe323 29113(gdb)
922fbb7b
AC
29114@end smallexample
29115
18148017
VP
29116@subheading The @code{-break-passcount} Command
29117@findex -break-passcount
29118
29119@subsubheading Synopsis
29120
29121@smallexample
29122 -break-passcount @var{tracepoint-number} @var{passcount}
29123@end smallexample
29124
29125Set the passcount for tracepoint @var{tracepoint-number} to
29126@var{passcount}. If the breakpoint referred to by @var{tracepoint-number}
29127is not a tracepoint, error is emitted. This corresponds to CLI
29128command @samp{passcount}.
29129
922fbb7b
AC
29130@subheading The @code{-break-watch} Command
29131@findex -break-watch
29132
29133@subsubheading Synopsis
29134
29135@smallexample
29136 -break-watch [ -a | -r ]
29137@end smallexample
29138
29139Create a watchpoint. With the @samp{-a} option it will create an
d3e8051b 29140@dfn{access} watchpoint, i.e., a watchpoint that triggers either on a
922fbb7b 29141read from or on a write to the memory location. With the @samp{-r}
d3e8051b 29142option, the watchpoint created is a @dfn{read} watchpoint, i.e., it will
922fbb7b
AC
29143trigger only when the memory location is accessed for reading. Without
29144either of the options, the watchpoint created is a regular watchpoint,
d3e8051b 29145i.e., it will trigger when the memory location is accessed for writing.
79a6e687 29146@xref{Set Watchpoints, , Setting Watchpoints}.
922fbb7b
AC
29147
29148Note that @samp{-break-list} will report a single list of watchpoints and
29149breakpoints inserted.
29150
29151@subsubheading @value{GDBN} Command
29152
29153The corresponding @value{GDBN} commands are @samp{watch}, @samp{awatch}, and
29154@samp{rwatch}.
29155
29156@subsubheading Example
29157
29158Setting a watchpoint on a variable in the @code{main} function:
29159
29160@smallexample
594fe323 29161(gdb)
922fbb7b
AC
29162-break-watch x
29163^done,wpt=@{number="2",exp="x"@}
594fe323 29164(gdb)
922fbb7b
AC
29165-exec-continue
29166^running
0869d01b
NR
29167(gdb)
29168*stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="x"@},
922fbb7b 29169value=@{old="-268439212",new="55"@},
76ff342d 29170frame=@{func="main",args=[],file="recursive2.c",
6d52907e 29171fullname="/home/foo/bar/recursive2.c",line="5",arch="i386:x86_64"@}
594fe323 29172(gdb)
922fbb7b
AC
29173@end smallexample
29174
29175Setting a watchpoint on a variable local to a function. @value{GDBN} will stop
29176the program execution twice: first for the variable changing value, then
29177for the watchpoint going out of scope.
29178
29179@smallexample
594fe323 29180(gdb)
922fbb7b
AC
29181-break-watch C
29182^done,wpt=@{number="5",exp="C"@}
594fe323 29183(gdb)
922fbb7b
AC
29184-exec-continue
29185^running
0869d01b
NR
29186(gdb)
29187*stopped,reason="watchpoint-trigger",
922fbb7b
AC
29188wpt=@{number="5",exp="C"@},value=@{old="-276895068",new="3"@},
29189frame=@{func="callee4",args=[],
76ff342d 29190file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
29191fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13",
29192arch="i386:x86_64"@}
594fe323 29193(gdb)
922fbb7b
AC
29194-exec-continue
29195^running
0869d01b
NR
29196(gdb)
29197*stopped,reason="watchpoint-scope",wpnum="5",
922fbb7b
AC
29198frame=@{func="callee3",args=[@{name="strarg",
29199value="0x11940 \"A string argument.\""@}],
76ff342d 29200file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
29201fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18",
29202arch="i386:x86_64"@}
594fe323 29203(gdb)
922fbb7b
AC
29204@end smallexample
29205
29206Listing breakpoints and watchpoints, at different points in the program
29207execution. Note that once the watchpoint goes out of scope, it is
29208deleted.
29209
29210@smallexample
594fe323 29211(gdb)
922fbb7b
AC
29212-break-watch C
29213^done,wpt=@{number="2",exp="C"@}
594fe323 29214(gdb)
922fbb7b
AC
29215-break-list
29216^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
29217hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
29218@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
29219@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
29220@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
29221@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
29222@{width="40",alignment="2",col_name="what",colhdr="What"@}],
29223body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
29224addr="0x00010734",func="callee4",
948d5102 29225file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
998580f1
MK
29226fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",thread-groups=["i1"],
29227times="1"@},
922fbb7b 29228bkpt=@{number="2",type="watchpoint",disp="keep",
998580f1 29229enabled="y",addr="",what="C",thread-groups=["i1"],times="0"@}]@}
594fe323 29230(gdb)
922fbb7b
AC
29231-exec-continue
29232^running
0869d01b
NR
29233(gdb)
29234*stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="C"@},
922fbb7b
AC
29235value=@{old="-276895068",new="3"@},
29236frame=@{func="callee4",args=[],
76ff342d 29237file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
29238fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13",
29239arch="i386:x86_64"@}
594fe323 29240(gdb)
922fbb7b
AC
29241-break-list
29242^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
29243hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
29244@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
29245@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
29246@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
29247@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
29248@{width="40",alignment="2",col_name="what",colhdr="What"@}],
29249body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
29250addr="0x00010734",func="callee4",
948d5102 29251file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
998580f1
MK
29252fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",thread-groups=["i1"],
29253times="1"@},
922fbb7b 29254bkpt=@{number="2",type="watchpoint",disp="keep",
998580f1 29255enabled="y",addr="",what="C",thread-groups=["i1"],times="-5"@}]@}
594fe323 29256(gdb)
922fbb7b
AC
29257-exec-continue
29258^running
29259^done,reason="watchpoint-scope",wpnum="2",
29260frame=@{func="callee3",args=[@{name="strarg",
29261value="0x11940 \"A string argument.\""@}],
76ff342d 29262file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
29263fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18",
29264arch="i386:x86_64"@}
594fe323 29265(gdb)
922fbb7b
AC
29266-break-list
29267^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
29268hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
29269@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
29270@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
29271@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
29272@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
29273@{width="40",alignment="2",col_name="what",colhdr="What"@}],
29274body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
29275addr="0x00010734",func="callee4",
948d5102
NR
29276file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
29277fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
998580f1 29278thread-groups=["i1"],times="1"@}]@}
594fe323 29279(gdb)
922fbb7b
AC
29280@end smallexample
29281
3fa7bf06
MG
29282
29283@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
29284@node GDB/MI Catchpoint Commands
29285@section @sc{gdb/mi} Catchpoint Commands
29286
29287This section documents @sc{gdb/mi} commands for manipulating
29288catchpoints.
29289
40555925
JB
29290@menu
29291* Shared Library GDB/MI Catchpoint Commands::
29292* Ada Exception GDB/MI Catchpoint Commands::
29293@end menu
29294
29295@node Shared Library GDB/MI Catchpoint Commands
29296@subsection Shared Library @sc{gdb/mi} Catchpoints
29297
3fa7bf06
MG
29298@subheading The @code{-catch-load} Command
29299@findex -catch-load
29300
29301@subsubheading Synopsis
29302
29303@smallexample
29304 -catch-load [ -t ] [ -d ] @var{regexp}
29305@end smallexample
29306
29307Add a catchpoint for library load events. If the @samp{-t} option is used,
29308the catchpoint is a temporary one (@pxref{Set Breaks, ,Setting
29309Breakpoints}). If the @samp{-d} option is used, the catchpoint is created
29310in a disabled state. The @samp{regexp} argument is a regular
29311expression used to match the name of the loaded library.
29312
29313
29314@subsubheading @value{GDBN} Command
29315
29316The corresponding @value{GDBN} command is @samp{catch load}.
29317
29318@subsubheading Example
29319
29320@smallexample
29321-catch-load -t foo.so
29322^done,bkpt=@{number="1",type="catchpoint",disp="del",enabled="y",
8ac3646f 29323what="load of library matching foo.so",catch-type="load",times="0"@}
3fa7bf06
MG
29324(gdb)
29325@end smallexample
29326
29327
29328@subheading The @code{-catch-unload} Command
29329@findex -catch-unload
29330
29331@subsubheading Synopsis
29332
29333@smallexample
29334 -catch-unload [ -t ] [ -d ] @var{regexp}
29335@end smallexample
29336
29337Add a catchpoint for library unload events. If the @samp{-t} option is
29338used, the catchpoint is a temporary one (@pxref{Set Breaks, ,Setting
29339Breakpoints}). If the @samp{-d} option is used, the catchpoint is
29340created in a disabled state. The @samp{regexp} argument is a regular
29341expression used to match the name of the unloaded library.
29342
29343@subsubheading @value{GDBN} Command
29344
29345The corresponding @value{GDBN} command is @samp{catch unload}.
29346
29347@subsubheading Example
29348
29349@smallexample
29350-catch-unload -d bar.so
29351^done,bkpt=@{number="2",type="catchpoint",disp="keep",enabled="n",
8ac3646f 29352what="load of library matching bar.so",catch-type="unload",times="0"@}
3fa7bf06
MG
29353(gdb)
29354@end smallexample
29355
40555925
JB
29356@node Ada Exception GDB/MI Catchpoint Commands
29357@subsection Ada Exception @sc{gdb/mi} Catchpoints
29358
29359The following @sc{gdb/mi} commands can be used to create catchpoints
29360that stop the execution when Ada exceptions are being raised.
29361
29362@subheading The @code{-catch-assert} Command
29363@findex -catch-assert
29364
29365@subsubheading Synopsis
29366
29367@smallexample
29368 -catch-assert [ -c @var{condition}] [ -d ] [ -t ]
29369@end smallexample
29370
29371Add a catchpoint for failed Ada assertions.
29372
29373The possible optional parameters for this command are:
29374
29375@table @samp
29376@item -c @var{condition}
29377Make the catchpoint conditional on @var{condition}.
29378@item -d
29379Create a disabled catchpoint.
29380@item -t
29381Create a temporary catchpoint.
29382@end table
29383
29384@subsubheading @value{GDBN} Command
29385
29386The corresponding @value{GDBN} command is @samp{catch assert}.
29387
29388@subsubheading Example
29389
29390@smallexample
29391-catch-assert
29392^done,bkptno="5",bkpt=@{number="5",type="breakpoint",disp="keep",
29393enabled="y",addr="0x0000000000404888",what="failed Ada assertions",
29394thread-groups=["i1"],times="0",
29395original-location="__gnat_debug_raise_assert_failure"@}
29396(gdb)
29397@end smallexample
29398
29399@subheading The @code{-catch-exception} Command
29400@findex -catch-exception
29401
29402@subsubheading Synopsis
29403
29404@smallexample
29405 -catch-exception [ -c @var{condition}] [ -d ] [ -e @var{exception-name} ]
29406 [ -t ] [ -u ]
29407@end smallexample
29408
29409Add a catchpoint stopping when Ada exceptions are raised.
29410By default, the command stops the program when any Ada exception
29411gets raised. But it is also possible, by using some of the
29412optional parameters described below, to create more selective
29413catchpoints.
29414
29415The possible optional parameters for this command are:
29416
29417@table @samp
29418@item -c @var{condition}
29419Make the catchpoint conditional on @var{condition}.
29420@item -d
29421Create a disabled catchpoint.
29422@item -e @var{exception-name}
29423Only stop when @var{exception-name} is raised. This option cannot
29424be used combined with @samp{-u}.
29425@item -t
29426Create a temporary catchpoint.
29427@item -u
29428Stop only when an unhandled exception gets raised. This option
29429cannot be used combined with @samp{-e}.
29430@end table
29431
29432@subsubheading @value{GDBN} Command
29433
29434The corresponding @value{GDBN} commands are @samp{catch exception}
29435and @samp{catch exception unhandled}.
29436
29437@subsubheading Example
29438
29439@smallexample
29440-catch-exception -e Program_Error
29441^done,bkptno="4",bkpt=@{number="4",type="breakpoint",disp="keep",
29442enabled="y",addr="0x0000000000404874",
29443what="`Program_Error' Ada exception", thread-groups=["i1"],
29444times="0",original-location="__gnat_debug_raise_exception"@}
29445(gdb)
29446@end smallexample
3fa7bf06 29447
bea298f9
XR
29448@subheading The @code{-catch-handlers} Command
29449@findex -catch-handlers
29450
29451@subsubheading Synopsis
29452
29453@smallexample
29454 -catch-handlers [ -c @var{condition}] [ -d ] [ -e @var{exception-name} ]
29455 [ -t ]
29456@end smallexample
29457
29458Add a catchpoint stopping when Ada exceptions are handled.
29459By default, the command stops the program when any Ada exception
29460gets handled. But it is also possible, by using some of the
29461optional parameters described below, to create more selective
29462catchpoints.
29463
29464The possible optional parameters for this command are:
29465
29466@table @samp
29467@item -c @var{condition}
29468Make the catchpoint conditional on @var{condition}.
29469@item -d
29470Create a disabled catchpoint.
29471@item -e @var{exception-name}
29472Only stop when @var{exception-name} is handled.
29473@item -t
29474Create a temporary catchpoint.
29475@end table
29476
29477@subsubheading @value{GDBN} Command
29478
29479The corresponding @value{GDBN} command is @samp{catch handlers}.
29480
29481@subsubheading Example
29482
29483@smallexample
29484-catch-handlers -e Constraint_Error
29485^done,bkptno="4",bkpt=@{number="4",type="breakpoint",disp="keep",
29486enabled="y",addr="0x0000000000402f68",
29487what="`Constraint_Error' Ada exception handlers",thread-groups=["i1"],
29488times="0",original-location="__gnat_begin_handler"@}
29489(gdb)
29490@end smallexample
29491
922fbb7b 29492@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
a2c02241
NR
29493@node GDB/MI Program Context
29494@section @sc{gdb/mi} Program Context
922fbb7b 29495
a2c02241
NR
29496@subheading The @code{-exec-arguments} Command
29497@findex -exec-arguments
922fbb7b 29498
922fbb7b
AC
29499
29500@subsubheading Synopsis
29501
29502@smallexample
a2c02241 29503 -exec-arguments @var{args}
922fbb7b
AC
29504@end smallexample
29505
a2c02241
NR
29506Set the inferior program arguments, to be used in the next
29507@samp{-exec-run}.
922fbb7b 29508
a2c02241 29509@subsubheading @value{GDBN} Command
922fbb7b 29510
a2c02241 29511The corresponding @value{GDBN} command is @samp{set args}.
922fbb7b 29512
a2c02241 29513@subsubheading Example
922fbb7b 29514
fbc5282e
MK
29515@smallexample
29516(gdb)
29517-exec-arguments -v word
29518^done
29519(gdb)
29520@end smallexample
922fbb7b 29521
a2c02241 29522
9901a55b 29523@ignore
a2c02241
NR
29524@subheading The @code{-exec-show-arguments} Command
29525@findex -exec-show-arguments
29526
29527@subsubheading Synopsis
29528
29529@smallexample
29530 -exec-show-arguments
29531@end smallexample
29532
29533Print the arguments of the program.
922fbb7b
AC
29534
29535@subsubheading @value{GDBN} Command
29536
a2c02241 29537The corresponding @value{GDBN} command is @samp{show args}.
922fbb7b
AC
29538
29539@subsubheading Example
a2c02241 29540N.A.
9901a55b 29541@end ignore
922fbb7b 29542
922fbb7b 29543
a2c02241
NR
29544@subheading The @code{-environment-cd} Command
29545@findex -environment-cd
922fbb7b 29546
a2c02241 29547@subsubheading Synopsis
922fbb7b
AC
29548
29549@smallexample
a2c02241 29550 -environment-cd @var{pathdir}
922fbb7b
AC
29551@end smallexample
29552
a2c02241 29553Set @value{GDBN}'s working directory.
922fbb7b 29554
a2c02241 29555@subsubheading @value{GDBN} Command
922fbb7b 29556
a2c02241
NR
29557The corresponding @value{GDBN} command is @samp{cd}.
29558
29559@subsubheading Example
922fbb7b
AC
29560
29561@smallexample
594fe323 29562(gdb)
a2c02241
NR
29563-environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
29564^done
594fe323 29565(gdb)
922fbb7b
AC
29566@end smallexample
29567
29568
a2c02241
NR
29569@subheading The @code{-environment-directory} Command
29570@findex -environment-directory
922fbb7b
AC
29571
29572@subsubheading Synopsis
29573
29574@smallexample
a2c02241 29575 -environment-directory [ -r ] [ @var{pathdir} ]+
922fbb7b
AC
29576@end smallexample
29577
a2c02241
NR
29578Add directories @var{pathdir} to beginning of search path for source files.
29579If the @samp{-r} option is used, the search path is reset to the default
29580search path. If directories @var{pathdir} are supplied in addition to the
29581@samp{-r} option, the search path is first reset and then addition
29582occurs as normal.
29583Multiple directories may be specified, separated by blanks. Specifying
29584multiple directories in a single command
29585results in the directories added to the beginning of the
29586search path in the same order they were presented in the command.
29587If blanks are needed as
29588part of a directory name, double-quotes should be used around
29589the name. In the command output, the path will show up separated
d3e8051b 29590by the system directory-separator character. The directory-separator
a2c02241
NR
29591character must not be used
29592in any directory name.
29593If no directories are specified, the current search path is displayed.
922fbb7b
AC
29594
29595@subsubheading @value{GDBN} Command
29596
a2c02241 29597The corresponding @value{GDBN} command is @samp{dir}.
922fbb7b
AC
29598
29599@subsubheading Example
29600
922fbb7b 29601@smallexample
594fe323 29602(gdb)
a2c02241
NR
29603-environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
29604^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
594fe323 29605(gdb)
a2c02241
NR
29606-environment-directory ""
29607^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
594fe323 29608(gdb)
a2c02241
NR
29609-environment-directory -r /home/jjohnstn/src/gdb /usr/src
29610^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
594fe323 29611(gdb)
a2c02241
NR
29612-environment-directory -r
29613^done,source-path="$cdir:$cwd"
594fe323 29614(gdb)
922fbb7b
AC
29615@end smallexample
29616
29617
a2c02241
NR
29618@subheading The @code{-environment-path} Command
29619@findex -environment-path
922fbb7b
AC
29620
29621@subsubheading Synopsis
29622
29623@smallexample
a2c02241 29624 -environment-path [ -r ] [ @var{pathdir} ]+
922fbb7b
AC
29625@end smallexample
29626
a2c02241
NR
29627Add directories @var{pathdir} to beginning of search path for object files.
29628If the @samp{-r} option is used, the search path is reset to the original
29629search path that existed at gdb start-up. If directories @var{pathdir} are
29630supplied in addition to the
29631@samp{-r} option, the search path is first reset and then addition
29632occurs as normal.
29633Multiple directories may be specified, separated by blanks. Specifying
29634multiple directories in a single command
29635results in the directories added to the beginning of the
29636search path in the same order they were presented in the command.
29637If blanks are needed as
29638part of a directory name, double-quotes should be used around
29639the name. In the command output, the path will show up separated
d3e8051b 29640by the system directory-separator character. The directory-separator
a2c02241
NR
29641character must not be used
29642in any directory name.
29643If no directories are specified, the current path is displayed.
29644
922fbb7b
AC
29645
29646@subsubheading @value{GDBN} Command
29647
a2c02241 29648The corresponding @value{GDBN} command is @samp{path}.
922fbb7b
AC
29649
29650@subsubheading Example
29651
922fbb7b 29652@smallexample
594fe323 29653(gdb)
a2c02241
NR
29654-environment-path
29655^done,path="/usr/bin"
594fe323 29656(gdb)
a2c02241
NR
29657-environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
29658^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
594fe323 29659(gdb)
a2c02241
NR
29660-environment-path -r /usr/local/bin
29661^done,path="/usr/local/bin:/usr/bin"
594fe323 29662(gdb)
922fbb7b
AC
29663@end smallexample
29664
29665
a2c02241
NR
29666@subheading The @code{-environment-pwd} Command
29667@findex -environment-pwd
922fbb7b
AC
29668
29669@subsubheading Synopsis
29670
29671@smallexample
a2c02241 29672 -environment-pwd
922fbb7b
AC
29673@end smallexample
29674
a2c02241 29675Show the current working directory.
922fbb7b 29676
79a6e687 29677@subsubheading @value{GDBN} Command
922fbb7b 29678
a2c02241 29679The corresponding @value{GDBN} command is @samp{pwd}.
922fbb7b
AC
29680
29681@subsubheading Example
29682
922fbb7b 29683@smallexample
594fe323 29684(gdb)
a2c02241
NR
29685-environment-pwd
29686^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
594fe323 29687(gdb)
922fbb7b
AC
29688@end smallexample
29689
a2c02241
NR
29690@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
29691@node GDB/MI Thread Commands
29692@section @sc{gdb/mi} Thread Commands
29693
29694
29695@subheading The @code{-thread-info} Command
29696@findex -thread-info
922fbb7b
AC
29697
29698@subsubheading Synopsis
29699
29700@smallexample
8e8901c5 29701 -thread-info [ @var{thread-id} ]
922fbb7b
AC
29702@end smallexample
29703
5d5658a1
PA
29704Reports information about either a specific thread, if the
29705@var{thread-id} parameter is present, or about all threads.
29706@var{thread-id} is the thread's global thread ID. When printing
29707information about all threads, also reports the global ID of the
29708current thread.
8e8901c5 29709
79a6e687 29710@subsubheading @value{GDBN} Command
922fbb7b 29711
8e8901c5
VP
29712The @samp{info thread} command prints the same information
29713about all threads.
922fbb7b 29714
4694da01 29715@subsubheading Result
922fbb7b 29716
ebe553db 29717The result contains the following attributes:
4694da01
TT
29718
29719@table @samp
ebe553db
SM
29720@item threads
29721A list of threads. The format of the elements of the list is described in
29722@ref{GDB/MI Thread Information}.
29723
29724@item current-thread-id
29725The global id of the currently selected thread. This field is omitted if there
29726is no selected thread (for example, when the selected inferior is not running,
29727and therefore has no threads) or if a @var{thread-id} argument was passed to
29728the command.
4694da01
TT
29729
29730@end table
29731
29732@subsubheading Example
29733
29734@smallexample
29735-thread-info
29736^done,threads=[
29737@{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
29738 frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",
29739 args=[]@},state="running"@},
29740@{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
29741 frame=@{level="0",addr="0x0804891f",func="foo",
29742 args=[@{name="i",value="10"@}],
6d52907e 29743 file="/tmp/a.c",fullname="/tmp/a.c",line="158",arch="i386:x86_64"@},
4694da01
TT
29744 state="running"@}],
29745current-thread-id="1"
29746(gdb)
29747@end smallexample
29748
a2c02241
NR
29749@subheading The @code{-thread-list-ids} Command
29750@findex -thread-list-ids
922fbb7b 29751
a2c02241 29752@subsubheading Synopsis
922fbb7b 29753
a2c02241
NR
29754@smallexample
29755 -thread-list-ids
29756@end smallexample
922fbb7b 29757
5d5658a1
PA
29758Produces a list of the currently known global @value{GDBN} thread ids.
29759At the end of the list it also prints the total number of such
29760threads.
922fbb7b 29761
c3b108f7
VP
29762This command is retained for historical reasons, the
29763@code{-thread-info} command should be used instead.
29764
922fbb7b
AC
29765@subsubheading @value{GDBN} Command
29766
a2c02241 29767Part of @samp{info threads} supplies the same information.
922fbb7b
AC
29768
29769@subsubheading Example
29770
922fbb7b 29771@smallexample
594fe323 29772(gdb)
a2c02241
NR
29773-thread-list-ids
29774^done,thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
592375cd 29775current-thread-id="1",number-of-threads="3"
594fe323 29776(gdb)
922fbb7b
AC
29777@end smallexample
29778
a2c02241
NR
29779
29780@subheading The @code{-thread-select} Command
29781@findex -thread-select
922fbb7b
AC
29782
29783@subsubheading Synopsis
29784
29785@smallexample
5d5658a1 29786 -thread-select @var{thread-id}
922fbb7b
AC
29787@end smallexample
29788
5d5658a1
PA
29789Make thread with global thread number @var{thread-id} the current
29790thread. It prints the number of the new current thread, and the
29791topmost frame for that thread.
922fbb7b 29792
c3b108f7
VP
29793This command is deprecated in favor of explicitly using the
29794@samp{--thread} option to each command.
29795
922fbb7b
AC
29796@subsubheading @value{GDBN} Command
29797
a2c02241 29798The corresponding @value{GDBN} command is @samp{thread}.
922fbb7b
AC
29799
29800@subsubheading Example
922fbb7b
AC
29801
29802@smallexample
594fe323 29803(gdb)
a2c02241
NR
29804-exec-next
29805^running
594fe323 29806(gdb)
a2c02241
NR
29807*stopped,reason="end-stepping-range",thread-id="2",line="187",
29808file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
594fe323 29809(gdb)
a2c02241
NR
29810-thread-list-ids
29811^done,
29812thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
29813number-of-threads="3"
594fe323 29814(gdb)
a2c02241
NR
29815-thread-select 3
29816^done,new-thread-id="3",
29817frame=@{level="0",func="vprintf",
29818args=[@{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""@},
6d52907e 29819@{name="arg",value="0x2"@}],file="vprintf.c",line="31",arch="i386:x86_64"@}
594fe323 29820(gdb)
922fbb7b
AC
29821@end smallexample
29822
5d77fe44
JB
29823@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
29824@node GDB/MI Ada Tasking Commands
29825@section @sc{gdb/mi} Ada Tasking Commands
29826
29827@subheading The @code{-ada-task-info} Command
29828@findex -ada-task-info
29829
29830@subsubheading Synopsis
29831
29832@smallexample
29833 -ada-task-info [ @var{task-id} ]
29834@end smallexample
29835
29836Reports information about either a specific Ada task, if the
29837@var{task-id} parameter is present, or about all Ada tasks.
29838
29839@subsubheading @value{GDBN} Command
29840
29841The @samp{info tasks} command prints the same information
29842about all Ada tasks (@pxref{Ada Tasks}).
29843
29844@subsubheading Result
29845
29846The result is a table of Ada tasks. The following columns are
29847defined for each Ada task:
29848
29849@table @samp
29850@item current
29851This field exists only for the current thread. It has the value @samp{*}.
29852
29853@item id
29854The identifier that @value{GDBN} uses to refer to the Ada task.
29855
29856@item task-id
29857The identifier that the target uses to refer to the Ada task.
29858
29859@item thread-id
5d5658a1
PA
29860The global thread identifier of the thread corresponding to the Ada
29861task.
5d77fe44
JB
29862
29863This field should always exist, as Ada tasks are always implemented
29864on top of a thread. But if @value{GDBN} cannot find this corresponding
29865thread for any reason, the field is omitted.
29866
29867@item parent-id
29868This field exists only when the task was created by another task.
29869In this case, it provides the ID of the parent task.
29870
29871@item priority
29872The base priority of the task.
29873
29874@item state
29875The current state of the task. For a detailed description of the
29876possible states, see @ref{Ada Tasks}.
29877
29878@item name
29879The name of the task.
29880
29881@end table
29882
29883@subsubheading Example
29884
29885@smallexample
29886-ada-task-info
29887^done,tasks=@{nr_rows="3",nr_cols="8",
29888hdr=[@{width="1",alignment="-1",col_name="current",colhdr=""@},
29889@{width="3",alignment="1",col_name="id",colhdr="ID"@},
29890@{width="9",alignment="1",col_name="task-id",colhdr="TID"@},
29891@{width="4",alignment="1",col_name="thread-id",colhdr=""@},
29892@{width="4",alignment="1",col_name="parent-id",colhdr="P-ID"@},
29893@{width="3",alignment="1",col_name="priority",colhdr="Pri"@},
29894@{width="22",alignment="-1",col_name="state",colhdr="State"@},
29895@{width="1",alignment="2",col_name="name",colhdr="Name"@}],
29896body=[@{current="*",id="1",task-id=" 644010",thread-id="1",priority="48",
29897state="Child Termination Wait",name="main_task"@}]@}
29898(gdb)
29899@end smallexample
29900
a2c02241
NR
29901@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
29902@node GDB/MI Program Execution
29903@section @sc{gdb/mi} Program Execution
922fbb7b 29904
ef21caaf 29905These are the asynchronous commands which generate the out-of-band
3f94c067 29906record @samp{*stopped}. Currently @value{GDBN} only really executes
ef21caaf
NR
29907asynchronously with remote targets and this interaction is mimicked in
29908other cases.
922fbb7b 29909
922fbb7b
AC
29910@subheading The @code{-exec-continue} Command
29911@findex -exec-continue
29912
29913@subsubheading Synopsis
29914
29915@smallexample
540aa8e7 29916 -exec-continue [--reverse] [--all|--thread-group N]
922fbb7b
AC
29917@end smallexample
29918
540aa8e7
MS
29919Resumes the execution of the inferior program, which will continue
29920to execute until it reaches a debugger stop event. If the
29921@samp{--reverse} option is specified, execution resumes in reverse until
29922it reaches a stop event. Stop events may include
29923@itemize @bullet
29924@item
29925breakpoints or watchpoints
29926@item
29927signals or exceptions
29928@item
29929the end of the process (or its beginning under @samp{--reverse})
29930@item
29931the end or beginning of a replay log if one is being used.
29932@end itemize
29933In all-stop mode (@pxref{All-Stop
29934Mode}), may resume only one thread, or all threads, depending on the
29935value of the @samp{scheduler-locking} variable. If @samp{--all} is
a79b8f6e 29936specified, all threads (in all inferiors) will be resumed. The @samp{--all} option is
540aa8e7
MS
29937ignored in all-stop mode. If the @samp{--thread-group} options is
29938specified, then all threads in that thread group are resumed.
922fbb7b
AC
29939
29940@subsubheading @value{GDBN} Command
29941
29942The corresponding @value{GDBN} corresponding is @samp{continue}.
29943
29944@subsubheading Example
29945
29946@smallexample
29947-exec-continue
29948^running
594fe323 29949(gdb)
922fbb7b 29950@@Hello world
a47ec5fe
AR
29951*stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame=@{
29952func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c",
6d52907e 29953line="13",arch="i386:x86_64"@}
594fe323 29954(gdb)
922fbb7b
AC
29955@end smallexample
29956
29957
29958@subheading The @code{-exec-finish} Command
29959@findex -exec-finish
29960
29961@subsubheading Synopsis
29962
29963@smallexample
540aa8e7 29964 -exec-finish [--reverse]
922fbb7b
AC
29965@end smallexample
29966
ef21caaf
NR
29967Resumes the execution of the inferior program until the current
29968function is exited. Displays the results returned by the function.
540aa8e7
MS
29969If the @samp{--reverse} option is specified, resumes the reverse
29970execution of the inferior program until the point where current
29971function was called.
922fbb7b
AC
29972
29973@subsubheading @value{GDBN} Command
29974
29975The corresponding @value{GDBN} command is @samp{finish}.
29976
29977@subsubheading Example
29978
29979Function returning @code{void}.
29980
29981@smallexample
29982-exec-finish
29983^running
594fe323 29984(gdb)
922fbb7b
AC
29985@@hello from foo
29986*stopped,reason="function-finished",frame=@{func="main",args=[],
6d52907e 29987file="hello.c",fullname="/home/foo/bar/hello.c",line="7",arch="i386:x86_64"@}
594fe323 29988(gdb)
922fbb7b
AC
29989@end smallexample
29990
29991Function returning other than @code{void}. The name of the internal
29992@value{GDBN} variable storing the result is printed, together with the
29993value itself.
29994
29995@smallexample
29996-exec-finish
29997^running
594fe323 29998(gdb)
922fbb7b
AC
29999*stopped,reason="function-finished",frame=@{addr="0x000107b0",func="foo",
30000args=[@{name="a",value="1"],@{name="b",value="9"@}@},
6d52907e
JV
30001file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30002arch="i386:x86_64"@},
922fbb7b 30003gdb-result-var="$1",return-value="0"
594fe323 30004(gdb)
922fbb7b
AC
30005@end smallexample
30006
30007
30008@subheading The @code{-exec-interrupt} Command
30009@findex -exec-interrupt
30010
30011@subsubheading Synopsis
30012
30013@smallexample
c3b108f7 30014 -exec-interrupt [--all|--thread-group N]
922fbb7b
AC
30015@end smallexample
30016
ef21caaf
NR
30017Interrupts the background execution of the target. Note how the token
30018associated with the stop message is the one for the execution command
30019that has been interrupted. The token for the interrupt itself only
30020appears in the @samp{^done} output. If the user is trying to
922fbb7b
AC
30021interrupt a non-running program, an error message will be printed.
30022
c3b108f7
VP
30023Note that when asynchronous execution is enabled, this command is
30024asynchronous just like other execution commands. That is, first the
30025@samp{^done} response will be printed, and the target stop will be
30026reported after that using the @samp{*stopped} notification.
30027
30028In non-stop mode, only the context thread is interrupted by default.
a79b8f6e
VP
30029All threads (in all inferiors) will be interrupted if the
30030@samp{--all} option is specified. If the @samp{--thread-group}
30031option is specified, all threads in that group will be interrupted.
c3b108f7 30032
922fbb7b
AC
30033@subsubheading @value{GDBN} Command
30034
30035The corresponding @value{GDBN} command is @samp{interrupt}.
30036
30037@subsubheading Example
30038
30039@smallexample
594fe323 30040(gdb)
922fbb7b
AC
30041111-exec-continue
30042111^running
30043
594fe323 30044(gdb)
922fbb7b
AC
30045222-exec-interrupt
30046222^done
594fe323 30047(gdb)
922fbb7b 30048111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
76ff342d 30049frame=@{addr="0x00010140",func="foo",args=[],file="try.c",
6d52907e 30050fullname="/home/foo/bar/try.c",line="13",arch="i386:x86_64"@}
594fe323 30051(gdb)
922fbb7b 30052
594fe323 30053(gdb)
922fbb7b
AC
30054-exec-interrupt
30055^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
594fe323 30056(gdb)
922fbb7b
AC
30057@end smallexample
30058
83eba9b7
VP
30059@subheading The @code{-exec-jump} Command
30060@findex -exec-jump
30061
30062@subsubheading Synopsis
30063
30064@smallexample
30065 -exec-jump @var{location}
30066@end smallexample
30067
30068Resumes execution of the inferior program at the location specified by
30069parameter. @xref{Specify Location}, for a description of the
30070different forms of @var{location}.
30071
30072@subsubheading @value{GDBN} Command
30073
30074The corresponding @value{GDBN} command is @samp{jump}.
30075
30076@subsubheading Example
30077
30078@smallexample
30079-exec-jump foo.c:10
30080*running,thread-id="all"
30081^running
30082@end smallexample
30083
922fbb7b
AC
30084
30085@subheading The @code{-exec-next} Command
30086@findex -exec-next
30087
30088@subsubheading Synopsis
30089
30090@smallexample
540aa8e7 30091 -exec-next [--reverse]
922fbb7b
AC
30092@end smallexample
30093
ef21caaf
NR
30094Resumes execution of the inferior program, stopping when the beginning
30095of the next source line is reached.
922fbb7b 30096
540aa8e7
MS
30097If the @samp{--reverse} option is specified, resumes reverse execution
30098of the inferior program, stopping at the beginning of the previous
30099source line. If you issue this command on the first line of a
30100function, it will take you back to the caller of that function, to the
30101source line where the function was called.
30102
30103
922fbb7b
AC
30104@subsubheading @value{GDBN} Command
30105
30106The corresponding @value{GDBN} command is @samp{next}.
30107
30108@subsubheading Example
30109
30110@smallexample
30111-exec-next
30112^running
594fe323 30113(gdb)
922fbb7b 30114*stopped,reason="end-stepping-range",line="8",file="hello.c"
594fe323 30115(gdb)
922fbb7b
AC
30116@end smallexample
30117
30118
30119@subheading The @code{-exec-next-instruction} Command
30120@findex -exec-next-instruction
30121
30122@subsubheading Synopsis
30123
30124@smallexample
540aa8e7 30125 -exec-next-instruction [--reverse]
922fbb7b
AC
30126@end smallexample
30127
ef21caaf
NR
30128Executes one machine instruction. If the instruction is a function
30129call, continues until the function returns. If the program stops at an
30130instruction in the middle of a source line, the address will be
30131printed as well.
922fbb7b 30132
540aa8e7
MS
30133If the @samp{--reverse} option is specified, resumes reverse execution
30134of the inferior program, stopping at the previous instruction. If the
30135previously executed instruction was a return from another function,
30136it will continue to execute in reverse until the call to that function
30137(from the current stack frame) is reached.
30138
922fbb7b
AC
30139@subsubheading @value{GDBN} Command
30140
30141The corresponding @value{GDBN} command is @samp{nexti}.
30142
30143@subsubheading Example
30144
30145@smallexample
594fe323 30146(gdb)
922fbb7b
AC
30147-exec-next-instruction
30148^running
30149
594fe323 30150(gdb)
922fbb7b
AC
30151*stopped,reason="end-stepping-range",
30152addr="0x000100d4",line="5",file="hello.c"
594fe323 30153(gdb)
922fbb7b
AC
30154@end smallexample
30155
30156
30157@subheading The @code{-exec-return} Command
30158@findex -exec-return
30159
30160@subsubheading Synopsis
30161
30162@smallexample
30163 -exec-return
30164@end smallexample
30165
30166Makes current function return immediately. Doesn't execute the inferior.
30167Displays the new current frame.
30168
30169@subsubheading @value{GDBN} Command
30170
30171The corresponding @value{GDBN} command is @samp{return}.
30172
30173@subsubheading Example
30174
30175@smallexample
594fe323 30176(gdb)
922fbb7b
AC
30177200-break-insert callee4
30178200^done,bkpt=@{number="1",addr="0x00010734",
30179file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
594fe323 30180(gdb)
922fbb7b
AC
30181000-exec-run
30182000^running
594fe323 30183(gdb)
a47ec5fe 30184000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
922fbb7b 30185frame=@{func="callee4",args=[],
76ff342d 30186file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30187fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
30188arch="i386:x86_64"@}
594fe323 30189(gdb)
922fbb7b
AC
30190205-break-delete
30191205^done
594fe323 30192(gdb)
922fbb7b
AC
30193111-exec-return
30194111^done,frame=@{level="0",func="callee3",
30195args=[@{name="strarg",
30196value="0x11940 \"A string argument.\""@}],
76ff342d 30197file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30198fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18",
30199arch="i386:x86_64"@}
594fe323 30200(gdb)
922fbb7b
AC
30201@end smallexample
30202
30203
30204@subheading The @code{-exec-run} Command
30205@findex -exec-run
30206
30207@subsubheading Synopsis
30208
30209@smallexample
5713b9b5 30210 -exec-run [ --all | --thread-group N ] [ --start ]
922fbb7b
AC
30211@end smallexample
30212
ef21caaf
NR
30213Starts execution of the inferior from the beginning. The inferior
30214executes until either a breakpoint is encountered or the program
30215exits. In the latter case the output will include an exit code, if
30216the program has exited exceptionally.
922fbb7b 30217
5713b9b5
JB
30218When neither the @samp{--all} nor the @samp{--thread-group} option
30219is specified, the current inferior is started. If the
a79b8f6e
VP
30220@samp{--thread-group} option is specified, it should refer to a thread
30221group of type @samp{process}, and that thread group will be started.
30222If the @samp{--all} option is specified, then all inferiors will be started.
30223
5713b9b5
JB
30224Using the @samp{--start} option instructs the debugger to stop
30225the execution at the start of the inferior's main subprogram,
30226following the same behavior as the @code{start} command
30227(@pxref{Starting}).
30228
922fbb7b
AC
30229@subsubheading @value{GDBN} Command
30230
30231The corresponding @value{GDBN} command is @samp{run}.
30232
ef21caaf 30233@subsubheading Examples
922fbb7b
AC
30234
30235@smallexample
594fe323 30236(gdb)
922fbb7b
AC
30237-break-insert main
30238^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@}
594fe323 30239(gdb)
922fbb7b
AC
30240-exec-run
30241^running
594fe323 30242(gdb)
a47ec5fe 30243*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
76ff342d 30244frame=@{func="main",args=[],file="recursive2.c",
6d52907e 30245fullname="/home/foo/bar/recursive2.c",line="4",arch="i386:x86_64"@}
594fe323 30246(gdb)
922fbb7b
AC
30247@end smallexample
30248
ef21caaf
NR
30249@noindent
30250Program exited normally:
30251
30252@smallexample
594fe323 30253(gdb)
ef21caaf
NR
30254-exec-run
30255^running
594fe323 30256(gdb)
ef21caaf
NR
30257x = 55
30258*stopped,reason="exited-normally"
594fe323 30259(gdb)
ef21caaf
NR
30260@end smallexample
30261
30262@noindent
30263Program exited exceptionally:
30264
30265@smallexample
594fe323 30266(gdb)
ef21caaf
NR
30267-exec-run
30268^running
594fe323 30269(gdb)
ef21caaf
NR
30270x = 55
30271*stopped,reason="exited",exit-code="01"
594fe323 30272(gdb)
ef21caaf
NR
30273@end smallexample
30274
30275Another way the program can terminate is if it receives a signal such as
30276@code{SIGINT}. In this case, @sc{gdb/mi} displays this:
30277
30278@smallexample
594fe323 30279(gdb)
ef21caaf
NR
30280*stopped,reason="exited-signalled",signal-name="SIGINT",
30281signal-meaning="Interrupt"
30282@end smallexample
30283
922fbb7b 30284
a2c02241
NR
30285@c @subheading -exec-signal
30286
30287
30288@subheading The @code{-exec-step} Command
30289@findex -exec-step
922fbb7b
AC
30290
30291@subsubheading Synopsis
30292
30293@smallexample
540aa8e7 30294 -exec-step [--reverse]
922fbb7b
AC
30295@end smallexample
30296
a2c02241
NR
30297Resumes execution of the inferior program, stopping when the beginning
30298of the next source line is reached, if the next source line is not a
30299function call. If it is, stop at the first instruction of the called
540aa8e7
MS
30300function. If the @samp{--reverse} option is specified, resumes reverse
30301execution of the inferior program, stopping at the beginning of the
30302previously executed source line.
922fbb7b
AC
30303
30304@subsubheading @value{GDBN} Command
30305
a2c02241 30306The corresponding @value{GDBN} command is @samp{step}.
922fbb7b
AC
30307
30308@subsubheading Example
30309
30310Stepping into a function:
30311
30312@smallexample
30313-exec-step
30314^running
594fe323 30315(gdb)
922fbb7b
AC
30316*stopped,reason="end-stepping-range",
30317frame=@{func="foo",args=[@{name="a",value="10"@},
76ff342d 30318@{name="b",value="0"@}],file="recursive2.c",
6d52907e 30319fullname="/home/foo/bar/recursive2.c",line="11",arch="i386:x86_64"@}
594fe323 30320(gdb)
922fbb7b
AC
30321@end smallexample
30322
30323Regular stepping:
30324
30325@smallexample
30326-exec-step
30327^running
594fe323 30328(gdb)
922fbb7b 30329*stopped,reason="end-stepping-range",line="14",file="recursive2.c"
594fe323 30330(gdb)
922fbb7b
AC
30331@end smallexample
30332
30333
30334@subheading The @code{-exec-step-instruction} Command
30335@findex -exec-step-instruction
30336
30337@subsubheading Synopsis
30338
30339@smallexample
540aa8e7 30340 -exec-step-instruction [--reverse]
922fbb7b
AC
30341@end smallexample
30342
540aa8e7
MS
30343Resumes the inferior which executes one machine instruction. If the
30344@samp{--reverse} option is specified, resumes reverse execution of the
30345inferior program, stopping at the previously executed instruction.
30346The output, once @value{GDBN} has stopped, will vary depending on
30347whether we have stopped in the middle of a source line or not. In the
30348former case, the address at which the program stopped will be printed
30349as well.
922fbb7b
AC
30350
30351@subsubheading @value{GDBN} Command
30352
30353The corresponding @value{GDBN} command is @samp{stepi}.
30354
30355@subsubheading Example
30356
30357@smallexample
594fe323 30358(gdb)
922fbb7b
AC
30359-exec-step-instruction
30360^running
30361
594fe323 30362(gdb)
922fbb7b 30363*stopped,reason="end-stepping-range",
76ff342d 30364frame=@{func="foo",args=[],file="try.c",
6d52907e 30365fullname="/home/foo/bar/try.c",line="10",arch="i386:x86_64"@}
594fe323 30366(gdb)
922fbb7b
AC
30367-exec-step-instruction
30368^running
30369
594fe323 30370(gdb)
922fbb7b 30371*stopped,reason="end-stepping-range",
76ff342d 30372frame=@{addr="0x000100f4",func="foo",args=[],file="try.c",
6d52907e 30373fullname="/home/foo/bar/try.c",line="10",arch="i386:x86_64"@}
594fe323 30374(gdb)
922fbb7b
AC
30375@end smallexample
30376
30377
30378@subheading The @code{-exec-until} Command
30379@findex -exec-until
30380
30381@subsubheading Synopsis
30382
30383@smallexample
30384 -exec-until [ @var{location} ]
30385@end smallexample
30386
ef21caaf
NR
30387Executes the inferior until the @var{location} specified in the
30388argument is reached. If there is no argument, the inferior executes
30389until a source line greater than the current one is reached. The
30390reason for stopping in this case will be @samp{location-reached}.
922fbb7b
AC
30391
30392@subsubheading @value{GDBN} Command
30393
30394The corresponding @value{GDBN} command is @samp{until}.
30395
30396@subsubheading Example
30397
30398@smallexample
594fe323 30399(gdb)
922fbb7b
AC
30400-exec-until recursive2.c:6
30401^running
594fe323 30402(gdb)
922fbb7b
AC
30403x = 55
30404*stopped,reason="location-reached",frame=@{func="main",args=[],
6d52907e
JV
30405file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6",
30406arch="i386:x86_64"@}
594fe323 30407(gdb)
922fbb7b
AC
30408@end smallexample
30409
30410@ignore
30411@subheading -file-clear
30412Is this going away????
30413@end ignore
30414
351ff01a 30415@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
a2c02241
NR
30416@node GDB/MI Stack Manipulation
30417@section @sc{gdb/mi} Stack Manipulation Commands
351ff01a 30418
1e611234
PM
30419@subheading The @code{-enable-frame-filters} Command
30420@findex -enable-frame-filters
30421
30422@smallexample
30423-enable-frame-filters
30424@end smallexample
30425
30426@value{GDBN} allows Python-based frame filters to affect the output of
30427the MI commands relating to stack traces. As there is no way to
30428implement this in a fully backward-compatible way, a front end must
30429request that this functionality be enabled.
30430
30431Once enabled, this feature cannot be disabled.
30432
30433Note that if Python support has not been compiled into @value{GDBN},
30434this command will still succeed (and do nothing).
922fbb7b 30435
a2c02241
NR
30436@subheading The @code{-stack-info-frame} Command
30437@findex -stack-info-frame
922fbb7b
AC
30438
30439@subsubheading Synopsis
30440
30441@smallexample
a2c02241 30442 -stack-info-frame
922fbb7b
AC
30443@end smallexample
30444
a2c02241 30445Get info on the selected frame.
922fbb7b
AC
30446
30447@subsubheading @value{GDBN} Command
30448
a2c02241
NR
30449The corresponding @value{GDBN} command is @samp{info frame} or @samp{frame}
30450(without arguments).
922fbb7b
AC
30451
30452@subsubheading Example
30453
30454@smallexample
594fe323 30455(gdb)
a2c02241
NR
30456-stack-info-frame
30457^done,frame=@{level="1",addr="0x0001076c",func="callee3",
30458file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30459fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17",
30460arch="i386:x86_64"@}
594fe323 30461(gdb)
922fbb7b
AC
30462@end smallexample
30463
a2c02241
NR
30464@subheading The @code{-stack-info-depth} Command
30465@findex -stack-info-depth
922fbb7b
AC
30466
30467@subsubheading Synopsis
30468
30469@smallexample
a2c02241 30470 -stack-info-depth [ @var{max-depth} ]
922fbb7b
AC
30471@end smallexample
30472
a2c02241
NR
30473Return the depth of the stack. If the integer argument @var{max-depth}
30474is specified, do not count beyond @var{max-depth} frames.
922fbb7b
AC
30475
30476@subsubheading @value{GDBN} Command
30477
a2c02241 30478There's no equivalent @value{GDBN} command.
922fbb7b
AC
30479
30480@subsubheading Example
30481
a2c02241
NR
30482For a stack with frame levels 0 through 11:
30483
922fbb7b 30484@smallexample
594fe323 30485(gdb)
a2c02241
NR
30486-stack-info-depth
30487^done,depth="12"
594fe323 30488(gdb)
a2c02241
NR
30489-stack-info-depth 4
30490^done,depth="4"
594fe323 30491(gdb)
a2c02241
NR
30492-stack-info-depth 12
30493^done,depth="12"
594fe323 30494(gdb)
a2c02241
NR
30495-stack-info-depth 11
30496^done,depth="11"
594fe323 30497(gdb)
a2c02241
NR
30498-stack-info-depth 13
30499^done,depth="12"
594fe323 30500(gdb)
922fbb7b
AC
30501@end smallexample
30502
1e611234 30503@anchor{-stack-list-arguments}
a2c02241
NR
30504@subheading The @code{-stack-list-arguments} Command
30505@findex -stack-list-arguments
922fbb7b
AC
30506
30507@subsubheading Synopsis
30508
30509@smallexample
6211c335 30510 -stack-list-arguments [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
a2c02241 30511 [ @var{low-frame} @var{high-frame} ]
922fbb7b
AC
30512@end smallexample
30513
a2c02241
NR
30514Display a list of the arguments for the frames between @var{low-frame}
30515and @var{high-frame} (inclusive). If @var{low-frame} and
2f1acb09
VP
30516@var{high-frame} are not provided, list the arguments for the whole
30517call stack. If the two arguments are equal, show the single frame
30518at the corresponding level. It is an error if @var{low-frame} is
30519larger than the actual number of frames. On the other hand,
30520@var{high-frame} may be larger than the actual number of frames, in
30521which case only existing frames will be returned.
a2c02241 30522
3afae151
VP
30523If @var{print-values} is 0 or @code{--no-values}, print only the names of
30524the variables; if it is 1 or @code{--all-values}, print also their
30525values; and if it is 2 or @code{--simple-values}, print the name,
30526type and value for simple data types, and the name and type for arrays,
1e611234
PM
30527structures and unions. If the option @code{--no-frame-filters} is
30528supplied, then Python frame filters will not be executed.
30529
6211c335
YQ
30530If the @code{--skip-unavailable} option is specified, arguments that
30531are not available are not listed. Partially available arguments
30532are still displayed, however.
922fbb7b 30533
b3372f91
VP
30534Use of this command to obtain arguments in a single frame is
30535deprecated in favor of the @samp{-stack-list-variables} command.
30536
922fbb7b
AC
30537@subsubheading @value{GDBN} Command
30538
a2c02241
NR
30539@value{GDBN} does not have an equivalent command. @code{gdbtk} has a
30540@samp{gdb_get_args} command which partially overlaps with the
30541functionality of @samp{-stack-list-arguments}.
922fbb7b
AC
30542
30543@subsubheading Example
922fbb7b 30544
a2c02241 30545@smallexample
594fe323 30546(gdb)
a2c02241
NR
30547-stack-list-frames
30548^done,
30549stack=[
30550frame=@{level="0",addr="0x00010734",func="callee4",
30551file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30552fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
30553arch="i386:x86_64"@},
a2c02241
NR
30554frame=@{level="1",addr="0x0001076c",func="callee3",
30555file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30556fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17",
30557arch="i386:x86_64"@},
a2c02241
NR
30558frame=@{level="2",addr="0x0001078c",func="callee2",
30559file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30560fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22",
30561arch="i386:x86_64"@},
a2c02241
NR
30562frame=@{level="3",addr="0x000107b4",func="callee1",
30563file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30564fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27",
30565arch="i386:x86_64"@},
a2c02241
NR
30566frame=@{level="4",addr="0x000107e0",func="main",
30567file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
6d52907e
JV
30568fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32",
30569arch="i386:x86_64"@}]
594fe323 30570(gdb)
a2c02241
NR
30571-stack-list-arguments 0
30572^done,
30573stack-args=[
30574frame=@{level="0",args=[]@},
30575frame=@{level="1",args=[name="strarg"]@},
30576frame=@{level="2",args=[name="intarg",name="strarg"]@},
30577frame=@{level="3",args=[name="intarg",name="strarg",name="fltarg"]@},
30578frame=@{level="4",args=[]@}]
594fe323 30579(gdb)
a2c02241
NR
30580-stack-list-arguments 1
30581^done,
30582stack-args=[
30583frame=@{level="0",args=[]@},
30584frame=@{level="1",
30585 args=[@{name="strarg",value="0x11940 \"A string argument.\""@}]@},
30586frame=@{level="2",args=[
30587@{name="intarg",value="2"@},
30588@{name="strarg",value="0x11940 \"A string argument.\""@}]@},
30589@{frame=@{level="3",args=[
30590@{name="intarg",value="2"@},
30591@{name="strarg",value="0x11940 \"A string argument.\""@},
30592@{name="fltarg",value="3.5"@}]@},
30593frame=@{level="4",args=[]@}]
594fe323 30594(gdb)
a2c02241
NR
30595-stack-list-arguments 0 2 2
30596^done,stack-args=[frame=@{level="2",args=[name="intarg",name="strarg"]@}]
594fe323 30597(gdb)
a2c02241
NR
30598-stack-list-arguments 1 2 2
30599^done,stack-args=[frame=@{level="2",
30600args=[@{name="intarg",value="2"@},
30601@{name="strarg",value="0x11940 \"A string argument.\""@}]@}]
594fe323 30602(gdb)
a2c02241
NR
30603@end smallexample
30604
30605@c @subheading -stack-list-exception-handlers
922fbb7b 30606
a2c02241 30607
1e611234 30608@anchor{-stack-list-frames}
a2c02241
NR
30609@subheading The @code{-stack-list-frames} Command
30610@findex -stack-list-frames
1abaf70c
BR
30611
30612@subsubheading Synopsis
30613
30614@smallexample
1e611234 30615 -stack-list-frames [ --no-frame-filters @var{low-frame} @var{high-frame} ]
1abaf70c
BR
30616@end smallexample
30617
a2c02241
NR
30618List the frames currently on the stack. For each frame it displays the
30619following info:
30620
30621@table @samp
30622@item @var{level}
d3e8051b 30623The frame number, 0 being the topmost frame, i.e., the innermost function.
a2c02241
NR
30624@item @var{addr}
30625The @code{$pc} value for that frame.
30626@item @var{func}
30627Function name.
30628@item @var{file}
30629File name of the source file where the function lives.
7d288aaa
TT
30630@item @var{fullname}
30631The full file name of the source file where the function lives.
a2c02241
NR
30632@item @var{line}
30633Line number corresponding to the @code{$pc}.
7d288aaa
TT
30634@item @var{from}
30635The shared library where this function is defined. This is only given
30636if the frame's function is not known.
6d52907e
JV
30637@item @var{arch}
30638Frame's architecture.
a2c02241
NR
30639@end table
30640
30641If invoked without arguments, this command prints a backtrace for the
30642whole stack. If given two integer arguments, it shows the frames whose
30643levels are between the two arguments (inclusive). If the two arguments
2ab1eb7a
VP
30644are equal, it shows the single frame at the corresponding level. It is
30645an error if @var{low-frame} is larger than the actual number of
a5451f4e 30646frames. On the other hand, @var{high-frame} may be larger than the
1e611234
PM
30647actual number of frames, in which case only existing frames will be
30648returned. If the option @code{--no-frame-filters} is supplied, then
30649Python frame filters will not be executed.
1abaf70c
BR
30650
30651@subsubheading @value{GDBN} Command
30652
a2c02241 30653The corresponding @value{GDBN} commands are @samp{backtrace} and @samp{where}.
1abaf70c
BR
30654
30655@subsubheading Example
30656
a2c02241
NR
30657Full stack backtrace:
30658
1abaf70c 30659@smallexample
594fe323 30660(gdb)
a2c02241
NR
30661-stack-list-frames
30662^done,stack=
30663[frame=@{level="0",addr="0x0001076c",func="foo",
6d52907e
JV
30664 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11",
30665 arch="i386:x86_64"@},
a2c02241 30666frame=@{level="1",addr="0x000107a4",func="foo",
6d52907e
JV
30667 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30668 arch="i386:x86_64"@},
a2c02241 30669frame=@{level="2",addr="0x000107a4",func="foo",
6d52907e
JV
30670 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30671 arch="i386:x86_64"@},
a2c02241 30672frame=@{level="3",addr="0x000107a4",func="foo",
6d52907e
JV
30673 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30674 arch="i386:x86_64"@},
a2c02241 30675frame=@{level="4",addr="0x000107a4",func="foo",
6d52907e
JV
30676 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30677 arch="i386:x86_64"@},
a2c02241 30678frame=@{level="5",addr="0x000107a4",func="foo",
6d52907e
JV
30679 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30680 arch="i386:x86_64"@},
a2c02241 30681frame=@{level="6",addr="0x000107a4",func="foo",
6d52907e
JV
30682 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30683 arch="i386:x86_64"@},
a2c02241 30684frame=@{level="7",addr="0x000107a4",func="foo",
6d52907e
JV
30685 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30686 arch="i386:x86_64"@},
a2c02241 30687frame=@{level="8",addr="0x000107a4",func="foo",
6d52907e
JV
30688 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30689 arch="i386:x86_64"@},
a2c02241 30690frame=@{level="9",addr="0x000107a4",func="foo",
6d52907e
JV
30691 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30692 arch="i386:x86_64"@},
a2c02241 30693frame=@{level="10",addr="0x000107a4",func="foo",
6d52907e
JV
30694 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30695 arch="i386:x86_64"@},
a2c02241 30696frame=@{level="11",addr="0x00010738",func="main",
6d52907e
JV
30697 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4",
30698 arch="i386:x86_64"@}]
594fe323 30699(gdb)
1abaf70c
BR
30700@end smallexample
30701
a2c02241 30702Show frames between @var{low_frame} and @var{high_frame}:
1abaf70c 30703
a2c02241 30704@smallexample
594fe323 30705(gdb)
a2c02241
NR
30706-stack-list-frames 3 5
30707^done,stack=
30708[frame=@{level="3",addr="0x000107a4",func="foo",
6d52907e
JV
30709 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30710 arch="i386:x86_64"@},
a2c02241 30711frame=@{level="4",addr="0x000107a4",func="foo",
6d52907e
JV
30712 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30713 arch="i386:x86_64"@},
a2c02241 30714frame=@{level="5",addr="0x000107a4",func="foo",
6d52907e
JV
30715 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30716 arch="i386:x86_64"@}]
594fe323 30717(gdb)
a2c02241 30718@end smallexample
922fbb7b 30719
a2c02241 30720Show a single frame:
922fbb7b
AC
30721
30722@smallexample
594fe323 30723(gdb)
a2c02241
NR
30724-stack-list-frames 3 3
30725^done,stack=
30726[frame=@{level="3",addr="0x000107a4",func="foo",
6d52907e
JV
30727 file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14",
30728 arch="i386:x86_64"@}]
594fe323 30729(gdb)
922fbb7b
AC
30730@end smallexample
30731
922fbb7b 30732
a2c02241
NR
30733@subheading The @code{-stack-list-locals} Command
30734@findex -stack-list-locals
1e611234 30735@anchor{-stack-list-locals}
57c22c6c 30736
a2c02241 30737@subsubheading Synopsis
922fbb7b
AC
30738
30739@smallexample
6211c335 30740 -stack-list-locals [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
922fbb7b
AC
30741@end smallexample
30742
a2c02241
NR
30743Display the local variable names for the selected frame. If
30744@var{print-values} is 0 or @code{--no-values}, print only the names of
30745the variables; if it is 1 or @code{--all-values}, print also their
30746values; and if it is 2 or @code{--simple-values}, print the name,
3afae151 30747type and value for simple data types, and the name and type for arrays,
a2c02241
NR
30748structures and unions. In this last case, a frontend can immediately
30749display the value of simple data types and create variable objects for
d3e8051b 30750other data types when the user wishes to explore their values in
1e611234
PM
30751more detail. If the option @code{--no-frame-filters} is supplied, then
30752Python frame filters will not be executed.
922fbb7b 30753
6211c335
YQ
30754If the @code{--skip-unavailable} option is specified, local variables
30755that are not available are not listed. Partially available local
30756variables are still displayed, however.
30757
b3372f91
VP
30758This command is deprecated in favor of the
30759@samp{-stack-list-variables} command.
30760
922fbb7b
AC
30761@subsubheading @value{GDBN} Command
30762
a2c02241 30763@samp{info locals} in @value{GDBN}, @samp{gdb_get_locals} in @code{gdbtk}.
922fbb7b
AC
30764
30765@subsubheading Example
922fbb7b
AC
30766
30767@smallexample
594fe323 30768(gdb)
a2c02241
NR
30769-stack-list-locals 0
30770^done,locals=[name="A",name="B",name="C"]
594fe323 30771(gdb)
a2c02241
NR
30772-stack-list-locals --all-values
30773^done,locals=[@{name="A",value="1"@},@{name="B",value="2"@},
30774 @{name="C",value="@{1, 2, 3@}"@}]
30775-stack-list-locals --simple-values
30776^done,locals=[@{name="A",type="int",value="1"@},
30777 @{name="B",type="int",value="2"@},@{name="C",type="int [3]"@}]
594fe323 30778(gdb)
922fbb7b
AC
30779@end smallexample
30780
1e611234 30781@anchor{-stack-list-variables}
b3372f91
VP
30782@subheading The @code{-stack-list-variables} Command
30783@findex -stack-list-variables
30784
30785@subsubheading Synopsis
30786
30787@smallexample
6211c335 30788 -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] @var{print-values}
b3372f91
VP
30789@end smallexample
30790
30791Display the names of local variables and function arguments for the selected frame. If
30792@var{print-values} is 0 or @code{--no-values}, print only the names of
30793the variables; if it is 1 or @code{--all-values}, print also their
30794values; and if it is 2 or @code{--simple-values}, print the name,
3afae151 30795type and value for simple data types, and the name and type for arrays,
1e611234
PM
30796structures and unions. If the option @code{--no-frame-filters} is
30797supplied, then Python frame filters will not be executed.
b3372f91 30798
6211c335
YQ
30799If the @code{--skip-unavailable} option is specified, local variables
30800and arguments that are not available are not listed. Partially
30801available arguments and local variables are still displayed, however.
30802
b3372f91
VP
30803@subsubheading Example
30804
30805@smallexample
30806(gdb)
30807-stack-list-variables --thread 1 --frame 0 --all-values
4f412fd0 30808^done,variables=[@{name="x",value="11"@},@{name="s",value="@{a = 1, b = 2@}"@}]
b3372f91
VP
30809(gdb)
30810@end smallexample
30811
922fbb7b 30812
a2c02241
NR
30813@subheading The @code{-stack-select-frame} Command
30814@findex -stack-select-frame
922fbb7b
AC
30815
30816@subsubheading Synopsis
30817
30818@smallexample
a2c02241 30819 -stack-select-frame @var{framenum}
922fbb7b
AC
30820@end smallexample
30821
a2c02241
NR
30822Change the selected frame. Select a different frame @var{framenum} on
30823the stack.
922fbb7b 30824
c3b108f7
VP
30825This command in deprecated in favor of passing the @samp{--frame}
30826option to every command.
30827
922fbb7b
AC
30828@subsubheading @value{GDBN} Command
30829
a2c02241
NR
30830The corresponding @value{GDBN} commands are @samp{frame}, @samp{up},
30831@samp{down}, @samp{select-frame}, @samp{up-silent}, and @samp{down-silent}.
922fbb7b
AC
30832
30833@subsubheading Example
30834
30835@smallexample
594fe323 30836(gdb)
a2c02241 30837-stack-select-frame 2
922fbb7b 30838^done
594fe323 30839(gdb)
922fbb7b
AC
30840@end smallexample
30841
30842@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
a2c02241
NR
30843@node GDB/MI Variable Objects
30844@section @sc{gdb/mi} Variable Objects
922fbb7b 30845
a1b5960f 30846@ignore
922fbb7b 30847
a2c02241 30848@subheading Motivation for Variable Objects in @sc{gdb/mi}
922fbb7b 30849
a2c02241
NR
30850For the implementation of a variable debugger window (locals, watched
30851expressions, etc.), we are proposing the adaptation of the existing code
30852used by @code{Insight}.
922fbb7b 30853
a2c02241 30854The two main reasons for that are:
922fbb7b 30855
a2c02241
NR
30856@enumerate 1
30857@item
30858It has been proven in practice (it is already on its second generation).
922fbb7b 30859
a2c02241
NR
30860@item
30861It will shorten development time (needless to say how important it is
30862now).
30863@end enumerate
922fbb7b 30864
a2c02241
NR
30865The original interface was designed to be used by Tcl code, so it was
30866slightly changed so it could be used through @sc{gdb/mi}. This section
30867describes the @sc{gdb/mi} operations that will be available and gives some
30868hints about their use.
922fbb7b 30869
a2c02241
NR
30870@emph{Note}: In addition to the set of operations described here, we
30871expect the @sc{gui} implementation of a variable window to require, at
30872least, the following operations:
922fbb7b 30873
a2c02241
NR
30874@itemize @bullet
30875@item @code{-gdb-show} @code{output-radix}
30876@item @code{-stack-list-arguments}
30877@item @code{-stack-list-locals}
30878@item @code{-stack-select-frame}
30879@end itemize
922fbb7b 30880
a1b5960f
VP
30881@end ignore
30882
c8b2f53c 30883@subheading Introduction to Variable Objects
922fbb7b 30884
a2c02241 30885@cindex variable objects in @sc{gdb/mi}
c8b2f53c
VP
30886
30887Variable objects are "object-oriented" MI interface for examining and
30888changing values of expressions. Unlike some other MI interfaces that
30889work with expressions, variable objects are specifically designed for
30890simple and efficient presentation in the frontend. A variable object
30891is identified by string name. When a variable object is created, the
30892frontend specifies the expression for that variable object. The
30893expression can be a simple variable, or it can be an arbitrary complex
30894expression, and can even involve CPU registers. After creating a
30895variable object, the frontend can invoke other variable object
30896operations---for example to obtain or change the value of a variable
30897object, or to change display format.
30898
30899Variable objects have hierarchical tree structure. Any variable object
30900that corresponds to a composite type, such as structure in C, has
30901a number of child variable objects, for example corresponding to each
30902element of a structure. A child variable object can itself have
30903children, recursively. Recursion ends when we reach
25d5ea92
VP
30904leaf variable objects, which always have built-in types. Child variable
30905objects are created only by explicit request, so if a frontend
30906is not interested in the children of a particular variable object, no
30907child will be created.
c8b2f53c
VP
30908
30909For a leaf variable object it is possible to obtain its value as a
30910string, or set the value from a string. String value can be also
30911obtained for a non-leaf variable object, but it's generally a string
30912that only indicates the type of the object, and does not list its
30913contents. Assignment to a non-leaf variable object is not allowed.
30914
30915A frontend does not need to read the values of all variable objects each time
30916the program stops. Instead, MI provides an update command that lists all
30917variable objects whose values has changed since the last update
30918operation. This considerably reduces the amount of data that must
25d5ea92
VP
30919be transferred to the frontend. As noted above, children variable
30920objects are created on demand, and only leaf variable objects have a
30921real value. As result, gdb will read target memory only for leaf
30922variables that frontend has created.
30923
30924The automatic update is not always desirable. For example, a frontend
30925might want to keep a value of some expression for future reference,
30926and never update it. For another example, fetching memory is
30927relatively slow for embedded targets, so a frontend might want
30928to disable automatic update for the variables that are either not
30929visible on the screen, or ``closed''. This is possible using so
30930called ``frozen variable objects''. Such variable objects are never
30931implicitly updated.
922fbb7b 30932
c3b108f7
VP
30933Variable objects can be either @dfn{fixed} or @dfn{floating}. For the
30934fixed variable object, the expression is parsed when the variable
30935object is created, including associating identifiers to specific
30936variables. The meaning of expression never changes. For a floating
30937variable object the values of variables whose names appear in the
30938expressions are re-evaluated every time in the context of the current
30939frame. Consider this example:
30940
30941@smallexample
30942void do_work(...)
30943@{
30944 struct work_state state;
30945
30946 if (...)
30947 do_work(...);
30948@}
30949@end smallexample
30950
30951If a fixed variable object for the @code{state} variable is created in
7a9dd1b2 30952this function, and we enter the recursive call, the variable
c3b108f7
VP
30953object will report the value of @code{state} in the top-level
30954@code{do_work} invocation. On the other hand, a floating variable
30955object will report the value of @code{state} in the current frame.
30956
30957If an expression specified when creating a fixed variable object
30958refers to a local variable, the variable object becomes bound to the
30959thread and frame in which the variable object is created. When such
30960variable object is updated, @value{GDBN} makes sure that the
30961thread/frame combination the variable object is bound to still exists,
30962and re-evaluates the variable object in context of that thread/frame.
30963
a2c02241
NR
30964The following is the complete set of @sc{gdb/mi} operations defined to
30965access this functionality:
922fbb7b 30966
a2c02241
NR
30967@multitable @columnfractions .4 .6
30968@item @strong{Operation}
30969@tab @strong{Description}
922fbb7b 30970
0cc7d26f
TT
30971@item @code{-enable-pretty-printing}
30972@tab enable Python-based pretty-printing
a2c02241
NR
30973@item @code{-var-create}
30974@tab create a variable object
30975@item @code{-var-delete}
22d8a470 30976@tab delete the variable object and/or its children
a2c02241
NR
30977@item @code{-var-set-format}
30978@tab set the display format of this variable
30979@item @code{-var-show-format}
30980@tab show the display format of this variable
30981@item @code{-var-info-num-children}
30982@tab tells how many children this object has
30983@item @code{-var-list-children}
30984@tab return a list of the object's children
30985@item @code{-var-info-type}
30986@tab show the type of this variable object
30987@item @code{-var-info-expression}
02142340
VP
30988@tab print parent-relative expression that this variable object represents
30989@item @code{-var-info-path-expression}
30990@tab print full expression that this variable object represents
a2c02241
NR
30991@item @code{-var-show-attributes}
30992@tab is this variable editable? does it exist here?
30993@item @code{-var-evaluate-expression}
30994@tab get the value of this variable
30995@item @code{-var-assign}
30996@tab set the value of this variable
30997@item @code{-var-update}
30998@tab update the variable and its children
25d5ea92
VP
30999@item @code{-var-set-frozen}
31000@tab set frozeness attribute
0cc7d26f
TT
31001@item @code{-var-set-update-range}
31002@tab set range of children to display on update
a2c02241 31003@end multitable
922fbb7b 31004
a2c02241
NR
31005In the next subsection we describe each operation in detail and suggest
31006how it can be used.
922fbb7b 31007
a2c02241 31008@subheading Description And Use of Operations on Variable Objects
922fbb7b 31009
0cc7d26f
TT
31010@subheading The @code{-enable-pretty-printing} Command
31011@findex -enable-pretty-printing
31012
31013@smallexample
31014-enable-pretty-printing
31015@end smallexample
31016
31017@value{GDBN} allows Python-based visualizers to affect the output of the
31018MI variable object commands. However, because there was no way to
31019implement this in a fully backward-compatible way, a front end must
31020request that this functionality be enabled.
31021
31022Once enabled, this feature cannot be disabled.
31023
31024Note that if Python support has not been compiled into @value{GDBN},
31025this command will still succeed (and do nothing).
31026
f43030c4
TT
31027This feature is currently (as of @value{GDBN} 7.0) experimental, and
31028may work differently in future versions of @value{GDBN}.
31029
a2c02241
NR
31030@subheading The @code{-var-create} Command
31031@findex -var-create
ef21caaf 31032
a2c02241 31033@subsubheading Synopsis
ef21caaf 31034
a2c02241
NR
31035@smallexample
31036 -var-create @{@var{name} | "-"@}
c3b108f7 31037 @{@var{frame-addr} | "*" | "@@"@} @var{expression}
a2c02241
NR
31038@end smallexample
31039
31040This operation creates a variable object, which allows the monitoring of
31041a variable, the result of an expression, a memory cell or a CPU
31042register.
ef21caaf 31043
a2c02241
NR
31044The @var{name} parameter is the string by which the object can be
31045referenced. It must be unique. If @samp{-} is specified, the varobj
31046system will generate a string ``varNNNNNN'' automatically. It will be
c3b108f7 31047unique provided that one does not specify @var{name} of that format.
a2c02241 31048The command fails if a duplicate name is found.
ef21caaf 31049
a2c02241
NR
31050The frame under which the expression should be evaluated can be
31051specified by @var{frame-addr}. A @samp{*} indicates that the current
c3b108f7
VP
31052frame should be used. A @samp{@@} indicates that a floating variable
31053object must be created.
922fbb7b 31054
a2c02241
NR
31055@var{expression} is any expression valid on the current language set (must not
31056begin with a @samp{*}), or one of the following:
922fbb7b 31057
a2c02241
NR
31058@itemize @bullet
31059@item
31060@samp{*@var{addr}}, where @var{addr} is the address of a memory cell
922fbb7b 31061
a2c02241
NR
31062@item
31063@samp{*@var{addr}-@var{addr}} --- a memory address range (TBD)
922fbb7b 31064
a2c02241
NR
31065@item
31066@samp{$@var{regname}} --- a CPU register name
31067@end itemize
922fbb7b 31068
0cc7d26f
TT
31069@cindex dynamic varobj
31070A varobj's contents may be provided by a Python-based pretty-printer. In this
31071case the varobj is known as a @dfn{dynamic varobj}. Dynamic varobjs
31072have slightly different semantics in some cases. If the
31073@code{-enable-pretty-printing} command is not sent, then @value{GDBN}
31074will never create a dynamic varobj. This ensures backward
31075compatibility for existing clients.
31076
a2c02241 31077@subsubheading Result
922fbb7b 31078
0cc7d26f
TT
31079This operation returns attributes of the newly-created varobj. These
31080are:
31081
31082@table @samp
31083@item name
31084The name of the varobj.
31085
31086@item numchild
31087The number of children of the varobj. This number is not necessarily
31088reliable for a dynamic varobj. Instead, you must examine the
31089@samp{has_more} attribute.
31090
31091@item value
31092The varobj's scalar value. For a varobj whose type is some sort of
31093aggregate (e.g., a @code{struct}), or for a dynamic varobj, this value
31094will not be interesting.
31095
31096@item type
31097The varobj's type. This is a string representation of the type, as
8264ba82
AG
31098would be printed by the @value{GDBN} CLI. If @samp{print object}
31099(@pxref{Print Settings, set print object}) is set to @code{on}, the
31100@emph{actual} (derived) type of the object is shown rather than the
31101@emph{declared} one.
0cc7d26f
TT
31102
31103@item thread-id
31104If a variable object is bound to a specific thread, then this is the
5d5658a1 31105thread's global identifier.
0cc7d26f
TT
31106
31107@item has_more
31108For a dynamic varobj, this indicates whether there appear to be any
31109children available. For a non-dynamic varobj, this will be 0.
31110
31111@item dynamic
31112This attribute will be present and have the value @samp{1} if the
31113varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
31114then this attribute will not be present.
31115
31116@item displayhint
31117A dynamic varobj can supply a display hint to the front end. The
31118value comes directly from the Python pretty-printer object's
4c374409 31119@code{display_hint} method. @xref{Pretty Printing API}.
0cc7d26f
TT
31120@end table
31121
31122Typical output will look like this:
922fbb7b
AC
31123
31124@smallexample
0cc7d26f
TT
31125 name="@var{name}",numchild="@var{N}",type="@var{type}",thread-id="@var{M}",
31126 has_more="@var{has_more}"
dcaaae04
NR
31127@end smallexample
31128
a2c02241
NR
31129
31130@subheading The @code{-var-delete} Command
31131@findex -var-delete
922fbb7b
AC
31132
31133@subsubheading Synopsis
31134
31135@smallexample
22d8a470 31136 -var-delete [ -c ] @var{name}
922fbb7b
AC
31137@end smallexample
31138
a2c02241 31139Deletes a previously created variable object and all of its children.
22d8a470 31140With the @samp{-c} option, just deletes the children.
922fbb7b 31141
a2c02241 31142Returns an error if the object @var{name} is not found.
922fbb7b 31143
922fbb7b 31144
a2c02241
NR
31145@subheading The @code{-var-set-format} Command
31146@findex -var-set-format
922fbb7b 31147
a2c02241 31148@subsubheading Synopsis
922fbb7b
AC
31149
31150@smallexample
a2c02241 31151 -var-set-format @var{name} @var{format-spec}
922fbb7b
AC
31152@end smallexample
31153
a2c02241
NR
31154Sets the output format for the value of the object @var{name} to be
31155@var{format-spec}.
31156
de051565 31157@anchor{-var-set-format}
a2c02241
NR
31158The syntax for the @var{format-spec} is as follows:
31159
31160@smallexample
31161 @var{format-spec} @expansion{}
1c35a88f 31162 @{binary | decimal | hexadecimal | octal | natural | zero-hexadecimal@}
a2c02241
NR
31163@end smallexample
31164
c8b2f53c
VP
31165The natural format is the default format choosen automatically
31166based on the variable type (like decimal for an @code{int}, hex
31167for pointers, etc.).
31168
1c35a88f
LM
31169The zero-hexadecimal format has a representation similar to hexadecimal
31170but with padding zeroes to the left of the value. For example, a 32-bit
31171hexadecimal value of 0x1234 would be represented as 0x00001234 in the
31172zero-hexadecimal format.
31173
c8b2f53c
VP
31174For a variable with children, the format is set only on the
31175variable itself, and the children are not affected.
a2c02241
NR
31176
31177@subheading The @code{-var-show-format} Command
31178@findex -var-show-format
922fbb7b
AC
31179
31180@subsubheading Synopsis
31181
31182@smallexample
a2c02241 31183 -var-show-format @var{name}
922fbb7b
AC
31184@end smallexample
31185
a2c02241 31186Returns the format used to display the value of the object @var{name}.
922fbb7b 31187
a2c02241
NR
31188@smallexample
31189 @var{format} @expansion{}
31190 @var{format-spec}
31191@end smallexample
922fbb7b 31192
922fbb7b 31193
a2c02241
NR
31194@subheading The @code{-var-info-num-children} Command
31195@findex -var-info-num-children
31196
31197@subsubheading Synopsis
31198
31199@smallexample
31200 -var-info-num-children @var{name}
31201@end smallexample
31202
31203Returns the number of children of a variable object @var{name}:
31204
31205@smallexample
31206 numchild=@var{n}
31207@end smallexample
31208
0cc7d26f
TT
31209Note that this number is not completely reliable for a dynamic varobj.
31210It will return the current number of children, but more children may
31211be available.
31212
a2c02241
NR
31213
31214@subheading The @code{-var-list-children} Command
31215@findex -var-list-children
31216
31217@subsubheading Synopsis
31218
31219@smallexample
0cc7d26f 31220 -var-list-children [@var{print-values}] @var{name} [@var{from} @var{to}]
a2c02241 31221@end smallexample
b569d230 31222@anchor{-var-list-children}
a2c02241
NR
31223
31224Return a list of the children of the specified variable object and
31225create variable objects for them, if they do not already exist. With
f5011d11 31226a single argument or if @var{print-values} has a value of 0 or
a2c02241
NR
31227@code{--no-values}, print only the names of the variables; if
31228@var{print-values} is 1 or @code{--all-values}, also print their
31229values; and if it is 2 or @code{--simple-values} print the name and
31230value for simple data types and just the name for arrays, structures
31231and unions.
922fbb7b 31232
0cc7d26f
TT
31233@var{from} and @var{to}, if specified, indicate the range of children
31234to report. If @var{from} or @var{to} is less than zero, the range is
31235reset and all children will be reported. Otherwise, children starting
31236at @var{from} (zero-based) and up to and excluding @var{to} will be
31237reported.
31238
31239If a child range is requested, it will only affect the current call to
31240@code{-var-list-children}, but not future calls to @code{-var-update}.
31241For this, you must instead use @code{-var-set-update-range}. The
31242intent of this approach is to enable a front end to implement any
31243update approach it likes; for example, scrolling a view may cause the
31244front end to request more children with @code{-var-list-children}, and
31245then the front end could call @code{-var-set-update-range} with a
31246different range to ensure that future updates are restricted to just
31247the visible items.
31248
b569d230
EZ
31249For each child the following results are returned:
31250
31251@table @var
31252
31253@item name
31254Name of the variable object created for this child.
31255
31256@item exp
31257The expression to be shown to the user by the front end to designate this child.
31258For example this may be the name of a structure member.
31259
0cc7d26f
TT
31260For a dynamic varobj, this value cannot be used to form an
31261expression. There is no way to do this at all with a dynamic varobj.
31262
b569d230
EZ
31263For C/C@t{++} structures there are several pseudo children returned to
31264designate access qualifiers. For these pseudo children @var{exp} is
31265@samp{public}, @samp{private}, or @samp{protected}. In this case the
31266type and value are not present.
31267
0cc7d26f
TT
31268A dynamic varobj will not report the access qualifying
31269pseudo-children, regardless of the language. This information is not
31270available at all with a dynamic varobj.
31271
b569d230 31272@item numchild
0cc7d26f
TT
31273Number of children this child has. For a dynamic varobj, this will be
312740.
b569d230
EZ
31275
31276@item type
8264ba82
AG
31277The type of the child. If @samp{print object}
31278(@pxref{Print Settings, set print object}) is set to @code{on}, the
31279@emph{actual} (derived) type of the object is shown rather than the
31280@emph{declared} one.
b569d230
EZ
31281
31282@item value
31283If values were requested, this is the value.
31284
31285@item thread-id
5d5658a1
PA
31286If this variable object is associated with a thread, this is the
31287thread's global thread id. Otherwise this result is not present.
b569d230
EZ
31288
31289@item frozen
31290If the variable object is frozen, this variable will be present with a value of 1.
c78feb39 31291
9df9dbe0
YQ
31292@item displayhint
31293A dynamic varobj can supply a display hint to the front end. The
31294value comes directly from the Python pretty-printer object's
31295@code{display_hint} method. @xref{Pretty Printing API}.
31296
c78feb39
YQ
31297@item dynamic
31298This attribute will be present and have the value @samp{1} if the
31299varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
31300then this attribute will not be present.
31301
b569d230
EZ
31302@end table
31303
0cc7d26f
TT
31304The result may have its own attributes:
31305
31306@table @samp
31307@item displayhint
31308A dynamic varobj can supply a display hint to the front end. The
31309value comes directly from the Python pretty-printer object's
4c374409 31310@code{display_hint} method. @xref{Pretty Printing API}.
0cc7d26f
TT
31311
31312@item has_more
31313This is an integer attribute which is nonzero if there are children
31314remaining after the end of the selected range.
31315@end table
31316
922fbb7b
AC
31317@subsubheading Example
31318
31319@smallexample
594fe323 31320(gdb)
a2c02241 31321 -var-list-children n
b569d230 31322 ^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
a2c02241 31323 numchild=@var{n},type=@var{type}@},@r{(repeats N times)}]
594fe323 31324(gdb)
a2c02241 31325 -var-list-children --all-values n
b569d230 31326 ^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
a2c02241 31327 numchild=@var{n},value=@var{value},type=@var{type}@},@r{(repeats N times)}]
922fbb7b
AC
31328@end smallexample
31329
922fbb7b 31330
a2c02241
NR
31331@subheading The @code{-var-info-type} Command
31332@findex -var-info-type
922fbb7b 31333
a2c02241
NR
31334@subsubheading Synopsis
31335
31336@smallexample
31337 -var-info-type @var{name}
31338@end smallexample
31339
31340Returns the type of the specified variable @var{name}. The type is
31341returned as a string in the same format as it is output by the
31342@value{GDBN} CLI:
31343
31344@smallexample
31345 type=@var{typename}
31346@end smallexample
31347
31348
31349@subheading The @code{-var-info-expression} Command
31350@findex -var-info-expression
922fbb7b
AC
31351
31352@subsubheading Synopsis
31353
31354@smallexample
a2c02241 31355 -var-info-expression @var{name}
922fbb7b
AC
31356@end smallexample
31357
02142340
VP
31358Returns a string that is suitable for presenting this
31359variable object in user interface. The string is generally
31360not valid expression in the current language, and cannot be evaluated.
31361
31362For example, if @code{a} is an array, and variable object
31363@code{A} was created for @code{a}, then we'll get this output:
922fbb7b 31364
a2c02241 31365@smallexample
02142340
VP
31366(gdb) -var-info-expression A.1
31367^done,lang="C",exp="1"
a2c02241 31368@end smallexample
922fbb7b 31369
a2c02241 31370@noindent
fa4d0c40
YQ
31371Here, the value of @code{lang} is the language name, which can be
31372found in @ref{Supported Languages}.
02142340
VP
31373
31374Note that the output of the @code{-var-list-children} command also
31375includes those expressions, so the @code{-var-info-expression} command
31376is of limited use.
31377
31378@subheading The @code{-var-info-path-expression} Command
31379@findex -var-info-path-expression
31380
31381@subsubheading Synopsis
31382
31383@smallexample
31384 -var-info-path-expression @var{name}
31385@end smallexample
31386
31387Returns an expression that can be evaluated in the current
31388context and will yield the same value that a variable object has.
31389Compare this with the @code{-var-info-expression} command, which
31390result can be used only for UI presentation. Typical use of
31391the @code{-var-info-path-expression} command is creating a
31392watchpoint from a variable object.
31393
0cc7d26f
TT
31394This command is currently not valid for children of a dynamic varobj,
31395and will give an error when invoked on one.
31396
02142340
VP
31397For example, suppose @code{C} is a C@t{++} class, derived from class
31398@code{Base}, and that the @code{Base} class has a member called
31399@code{m_size}. Assume a variable @code{c} is has the type of
31400@code{C} and a variable object @code{C} was created for variable
31401@code{c}. Then, we'll get this output:
31402@smallexample
31403(gdb) -var-info-path-expression C.Base.public.m_size
31404^done,path_expr=((Base)c).m_size)
31405@end smallexample
922fbb7b 31406
a2c02241
NR
31407@subheading The @code{-var-show-attributes} Command
31408@findex -var-show-attributes
922fbb7b 31409
a2c02241 31410@subsubheading Synopsis
922fbb7b 31411
a2c02241
NR
31412@smallexample
31413 -var-show-attributes @var{name}
31414@end smallexample
922fbb7b 31415
a2c02241 31416List attributes of the specified variable object @var{name}:
922fbb7b
AC
31417
31418@smallexample
a2c02241 31419 status=@var{attr} [ ( ,@var{attr} )* ]
922fbb7b
AC
31420@end smallexample
31421
a2c02241
NR
31422@noindent
31423where @var{attr} is @code{@{ @{ editable | noneditable @} | TBD @}}.
31424
31425@subheading The @code{-var-evaluate-expression} Command
31426@findex -var-evaluate-expression
31427
31428@subsubheading Synopsis
31429
31430@smallexample
de051565 31431 -var-evaluate-expression [-f @var{format-spec}] @var{name}
a2c02241
NR
31432@end smallexample
31433
31434Evaluates the expression that is represented by the specified variable
de051565
MK
31435object and returns its value as a string. The format of the string
31436can be specified with the @samp{-f} option. The possible values of
31437this option are the same as for @code{-var-set-format}
31438(@pxref{-var-set-format}). If the @samp{-f} option is not specified,
31439the current display format will be used. The current display format
31440can be changed using the @code{-var-set-format} command.
a2c02241
NR
31441
31442@smallexample
31443 value=@var{value}
31444@end smallexample
31445
31446Note that one must invoke @code{-var-list-children} for a variable
31447before the value of a child variable can be evaluated.
31448
31449@subheading The @code{-var-assign} Command
31450@findex -var-assign
31451
31452@subsubheading Synopsis
31453
31454@smallexample
31455 -var-assign @var{name} @var{expression}
31456@end smallexample
31457
31458Assigns the value of @var{expression} to the variable object specified
31459by @var{name}. The object must be @samp{editable}. If the variable's
31460value is altered by the assign, the variable will show up in any
31461subsequent @code{-var-update} list.
31462
31463@subsubheading Example
922fbb7b
AC
31464
31465@smallexample
594fe323 31466(gdb)
a2c02241
NR
31467-var-assign var1 3
31468^done,value="3"
594fe323 31469(gdb)
a2c02241
NR
31470-var-update *
31471^done,changelist=[@{name="var1",in_scope="true",type_changed="false"@}]
594fe323 31472(gdb)
922fbb7b
AC
31473@end smallexample
31474
a2c02241
NR
31475@subheading The @code{-var-update} Command
31476@findex -var-update
31477
31478@subsubheading Synopsis
31479
31480@smallexample
31481 -var-update [@var{print-values}] @{@var{name} | "*"@}
31482@end smallexample
31483
c8b2f53c
VP
31484Reevaluate the expressions corresponding to the variable object
31485@var{name} and all its direct and indirect children, and return the
36ece8b3
NR
31486list of variable objects whose values have changed; @var{name} must
31487be a root variable object. Here, ``changed'' means that the result of
31488@code{-var-evaluate-expression} before and after the
31489@code{-var-update} is different. If @samp{*} is used as the variable
9f708cb2
VP
31490object names, all existing variable objects are updated, except
31491for frozen ones (@pxref{-var-set-frozen}). The option
36ece8b3 31492@var{print-values} determines whether both names and values, or just
de051565 31493names are printed. The possible values of this option are the same
36ece8b3
NR
31494as for @code{-var-list-children} (@pxref{-var-list-children}). It is
31495recommended to use the @samp{--all-values} option, to reduce the
31496number of MI commands needed on each program stop.
c8b2f53c 31497
c3b108f7
VP
31498With the @samp{*} parameter, if a variable object is bound to a
31499currently running thread, it will not be updated, without any
31500diagnostic.
a2c02241 31501
0cc7d26f
TT
31502If @code{-var-set-update-range} was previously used on a varobj, then
31503only the selected range of children will be reported.
922fbb7b 31504
0cc7d26f
TT
31505@code{-var-update} reports all the changed varobjs in a tuple named
31506@samp{changelist}.
31507
31508Each item in the change list is itself a tuple holding:
31509
31510@table @samp
31511@item name
31512The name of the varobj.
31513
31514@item value
31515If values were requested for this update, then this field will be
31516present and will hold the value of the varobj.
922fbb7b 31517
0cc7d26f 31518@item in_scope
9f708cb2 31519@anchor{-var-update}
0cc7d26f 31520This field is a string which may take one of three values:
36ece8b3
NR
31521
31522@table @code
31523@item "true"
31524The variable object's current value is valid.
31525
31526@item "false"
31527The variable object does not currently hold a valid value but it may
31528hold one in the future if its associated expression comes back into
31529scope.
31530
31531@item "invalid"
31532The variable object no longer holds a valid value.
31533This can occur when the executable file being debugged has changed,
31534either through recompilation or by using the @value{GDBN} @code{file}
31535command. The front end should normally choose to delete these variable
31536objects.
31537@end table
31538
31539In the future new values may be added to this list so the front should
31540be prepared for this possibility. @xref{GDB/MI Development and Front Ends, ,@sc{GDB/MI} Development and Front Ends}.
31541
0cc7d26f
TT
31542@item type_changed
31543This is only present if the varobj is still valid. If the type
31544changed, then this will be the string @samp{true}; otherwise it will
31545be @samp{false}.
31546
7191c139
JB
31547When a varobj's type changes, its children are also likely to have
31548become incorrect. Therefore, the varobj's children are automatically
31549deleted when this attribute is @samp{true}. Also, the varobj's update
31550range, when set using the @code{-var-set-update-range} command, is
31551unset.
31552
0cc7d26f
TT
31553@item new_type
31554If the varobj's type changed, then this field will be present and will
31555hold the new type.
31556
31557@item new_num_children
31558For a dynamic varobj, if the number of children changed, or if the
31559type changed, this will be the new number of children.
31560
31561The @samp{numchild} field in other varobj responses is generally not
31562valid for a dynamic varobj -- it will show the number of children that
31563@value{GDBN} knows about, but because dynamic varobjs lazily
31564instantiate their children, this will not reflect the number of
31565children which may be available.
31566
31567The @samp{new_num_children} attribute only reports changes to the
31568number of children known by @value{GDBN}. This is the only way to
31569detect whether an update has removed children (which necessarily can
31570only happen at the end of the update range).
31571
31572@item displayhint
31573The display hint, if any.
31574
31575@item has_more
31576This is an integer value, which will be 1 if there are more children
31577available outside the varobj's update range.
31578
31579@item dynamic
31580This attribute will be present and have the value @samp{1} if the
31581varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
31582then this attribute will not be present.
31583
31584@item new_children
31585If new children were added to a dynamic varobj within the selected
31586update range (as set by @code{-var-set-update-range}), then they will
31587be listed in this attribute.
31588@end table
31589
31590@subsubheading Example
31591
31592@smallexample
31593(gdb)
31594-var-assign var1 3
31595^done,value="3"
31596(gdb)
31597-var-update --all-values var1
31598^done,changelist=[@{name="var1",value="3",in_scope="true",
31599type_changed="false"@}]
31600(gdb)
31601@end smallexample
31602
25d5ea92
VP
31603@subheading The @code{-var-set-frozen} Command
31604@findex -var-set-frozen
9f708cb2 31605@anchor{-var-set-frozen}
25d5ea92
VP
31606
31607@subsubheading Synopsis
31608
31609@smallexample
9f708cb2 31610 -var-set-frozen @var{name} @var{flag}
25d5ea92
VP
31611@end smallexample
31612
9f708cb2 31613Set the frozenness flag on the variable object @var{name}. The
25d5ea92 31614@var{flag} parameter should be either @samp{1} to make the variable
9f708cb2 31615frozen or @samp{0} to make it unfrozen. If a variable object is
25d5ea92 31616frozen, then neither itself, nor any of its children, are
9f708cb2 31617implicitly updated by @code{-var-update} of
25d5ea92
VP
31618a parent variable or by @code{-var-update *}. Only
31619@code{-var-update} of the variable itself will update its value and
31620values of its children. After a variable object is unfrozen, it is
31621implicitly updated by all subsequent @code{-var-update} operations.
31622Unfreezing a variable does not update it, only subsequent
31623@code{-var-update} does.
31624
31625@subsubheading Example
31626
31627@smallexample
31628(gdb)
31629-var-set-frozen V 1
31630^done
31631(gdb)
31632@end smallexample
31633
0cc7d26f
TT
31634@subheading The @code{-var-set-update-range} command
31635@findex -var-set-update-range
31636@anchor{-var-set-update-range}
31637
31638@subsubheading Synopsis
31639
31640@smallexample
31641 -var-set-update-range @var{name} @var{from} @var{to}
31642@end smallexample
31643
31644Set the range of children to be returned by future invocations of
31645@code{-var-update}.
31646
31647@var{from} and @var{to} indicate the range of children to report. If
31648@var{from} or @var{to} is less than zero, the range is reset and all
31649children will be reported. Otherwise, children starting at @var{from}
31650(zero-based) and up to and excluding @var{to} will be reported.
31651
31652@subsubheading Example
31653
31654@smallexample
31655(gdb)
31656-var-set-update-range V 1 2
31657^done
31658@end smallexample
31659
b6313243
TT
31660@subheading The @code{-var-set-visualizer} command
31661@findex -var-set-visualizer
31662@anchor{-var-set-visualizer}
31663
31664@subsubheading Synopsis
31665
31666@smallexample
31667 -var-set-visualizer @var{name} @var{visualizer}
31668@end smallexample
31669
31670Set a visualizer for the variable object @var{name}.
31671
31672@var{visualizer} is the visualizer to use. The special value
31673@samp{None} means to disable any visualizer in use.
31674
31675If not @samp{None}, @var{visualizer} must be a Python expression.
31676This expression must evaluate to a callable object which accepts a
31677single argument. @value{GDBN} will call this object with the value of
31678the varobj @var{name} as an argument (this is done so that the same
31679Python pretty-printing code can be used for both the CLI and MI).
31680When called, this object must return an object which conforms to the
4c374409 31681pretty-printing interface (@pxref{Pretty Printing API}).
b6313243
TT
31682
31683The pre-defined function @code{gdb.default_visualizer} may be used to
31684select a visualizer by following the built-in process
31685(@pxref{Selecting Pretty-Printers}). This is done automatically when
31686a varobj is created, and so ordinarily is not needed.
31687
31688This feature is only available if Python support is enabled. The MI
d192b373 31689command @code{-list-features} (@pxref{GDB/MI Support Commands})
b6313243
TT
31690can be used to check this.
31691
31692@subsubheading Example
31693
31694Resetting the visualizer:
31695
31696@smallexample
31697(gdb)
31698-var-set-visualizer V None
31699^done
31700@end smallexample
31701
31702Reselecting the default (type-based) visualizer:
31703
31704@smallexample
31705(gdb)
31706-var-set-visualizer V gdb.default_visualizer
31707^done
31708@end smallexample
31709
31710Suppose @code{SomeClass} is a visualizer class. A lambda expression
31711can be used to instantiate this class for a varobj:
31712
31713@smallexample
31714(gdb)
31715-var-set-visualizer V "lambda val: SomeClass()"
31716^done
31717@end smallexample
25d5ea92 31718
a2c02241
NR
31719@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
31720@node GDB/MI Data Manipulation
31721@section @sc{gdb/mi} Data Manipulation
922fbb7b 31722
a2c02241
NR
31723@cindex data manipulation, in @sc{gdb/mi}
31724@cindex @sc{gdb/mi}, data manipulation
31725This section describes the @sc{gdb/mi} commands that manipulate data:
31726examine memory and registers, evaluate expressions, etc.
31727
a86c90e6
SM
31728For details about what an addressable memory unit is,
31729@pxref{addressable memory unit}.
31730
a2c02241
NR
31731@c REMOVED FROM THE INTERFACE.
31732@c @subheading -data-assign
31733@c Change the value of a program variable. Plenty of side effects.
79a6e687 31734@c @subsubheading GDB Command
a2c02241
NR
31735@c set variable
31736@c @subsubheading Example
31737@c N.A.
31738
31739@subheading The @code{-data-disassemble} Command
31740@findex -data-disassemble
922fbb7b
AC
31741
31742@subsubheading Synopsis
31743
31744@smallexample
a2c02241
NR
31745 -data-disassemble
31746 [ -s @var{start-addr} -e @var{end-addr} ]
26fb3983 31747 | [ -a @var{addr} ]
a2c02241
NR
31748 | [ -f @var{filename} -l @var{linenum} [ -n @var{lines} ] ]
31749 -- @var{mode}
922fbb7b
AC
31750@end smallexample
31751
a2c02241
NR
31752@noindent
31753Where:
31754
31755@table @samp
31756@item @var{start-addr}
31757is the beginning address (or @code{$pc})
31758@item @var{end-addr}
31759is the end address
26fb3983
JV
31760@item @var{addr}
31761is an address anywhere within (or the name of) the function to
31762disassemble. If an address is specified, the whole function
31763surrounding that address will be disassembled. If a name is
31764specified, the whole function with that name will be disassembled.
a2c02241
NR
31765@item @var{filename}
31766is the name of the file to disassemble
31767@item @var{linenum}
31768is the line number to disassemble around
31769@item @var{lines}
d3e8051b 31770is the number of disassembly lines to be produced. If it is -1,
a2c02241
NR
31771the whole function will be disassembled, in case no @var{end-addr} is
31772specified. If @var{end-addr} is specified as a non-zero value, and
31773@var{lines} is lower than the number of disassembly lines between
31774@var{start-addr} and @var{end-addr}, only @var{lines} lines are
31775displayed; if @var{lines} is higher than the number of lines between
31776@var{start-addr} and @var{end-addr}, only the lines up to @var{end-addr}
31777are displayed.
31778@item @var{mode}
6ff0ba5f
DE
31779is one of:
31780@itemize @bullet
31781@item 0 disassembly only
31782@item 1 mixed source and disassembly (deprecated)
31783@item 2 disassembly with raw opcodes
31784@item 3 mixed source and disassembly with raw opcodes (deprecated)
31785@item 4 mixed source and disassembly
31786@item 5 mixed source and disassembly with raw opcodes
31787@end itemize
31788
31789Modes 1 and 3 are deprecated. The output is ``source centric''
31790which hasn't proved useful in practice.
31791@xref{Machine Code}, for a discussion of the difference between
31792@code{/m} and @code{/s} output of the @code{disassemble} command.
a2c02241
NR
31793@end table
31794
31795@subsubheading Result
31796
ed8a1c2d
AB
31797The result of the @code{-data-disassemble} command will be a list named
31798@samp{asm_insns}, the contents of this list depend on the @var{mode}
31799used with the @code{-data-disassemble} command.
a2c02241 31800
ed8a1c2d
AB
31801For modes 0 and 2 the @samp{asm_insns} list contains tuples with the
31802following fields:
31803
31804@table @code
31805@item address
31806The address at which this instruction was disassembled.
31807
31808@item func-name
31809The name of the function this instruction is within.
31810
31811@item offset
31812The decimal offset in bytes from the start of @samp{func-name}.
31813
31814@item inst
31815The text disassembly for this @samp{address}.
31816
31817@item opcodes
6ff0ba5f 31818This field is only present for modes 2, 3 and 5. This contains the raw opcode
ed8a1c2d
AB
31819bytes for the @samp{inst} field.
31820
31821@end table
31822
6ff0ba5f 31823For modes 1, 3, 4 and 5 the @samp{asm_insns} list contains tuples named
ed8a1c2d 31824@samp{src_and_asm_line}, each of which has the following fields:
a2c02241 31825
ed8a1c2d
AB
31826@table @code
31827@item line
31828The line number within @samp{file}.
31829
31830@item file
31831The file name from the compilation unit. This might be an absolute
31832file name or a relative file name depending on the compile command
31833used.
31834
31835@item fullname
f35a17b5
JK
31836Absolute file name of @samp{file}. It is converted to a canonical form
31837using the source file search path
31838(@pxref{Source Path, ,Specifying Source Directories})
31839and after resolving all the symbolic links.
31840
31841If the source file is not found this field will contain the path as
31842present in the debug information.
ed8a1c2d
AB
31843
31844@item line_asm_insn
31845This is a list of tuples containing the disassembly for @samp{line} in
31846@samp{file}. The fields of each tuple are the same as for
31847@code{-data-disassemble} in @var{mode} 0 and 2, so @samp{address},
31848@samp{func-name}, @samp{offset}, @samp{inst}, and optionally
31849@samp{opcodes}.
31850
31851@end table
31852
31853Note that whatever included in the @samp{inst} field, is not
31854manipulated directly by @sc{gdb/mi}, i.e., it is not possible to
31855adjust its format.
922fbb7b
AC
31856
31857@subsubheading @value{GDBN} Command
31858
ed8a1c2d 31859The corresponding @value{GDBN} command is @samp{disassemble}.
922fbb7b
AC
31860
31861@subsubheading Example
31862
a2c02241
NR
31863Disassemble from the current value of @code{$pc} to @code{$pc + 20}:
31864
922fbb7b 31865@smallexample
594fe323 31866(gdb)
a2c02241
NR
31867-data-disassemble -s $pc -e "$pc + 20" -- 0
31868^done,
31869asm_insns=[
31870@{address="0x000107c0",func-name="main",offset="4",
31871inst="mov 2, %o0"@},
31872@{address="0x000107c4",func-name="main",offset="8",
31873inst="sethi %hi(0x11800), %o2"@},
31874@{address="0x000107c8",func-name="main",offset="12",
31875inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"@},
31876@{address="0x000107cc",func-name="main",offset="16",
31877inst="sethi %hi(0x11800), %o2"@},
31878@{address="0x000107d0",func-name="main",offset="20",
31879inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"@}]
594fe323 31880(gdb)
a2c02241
NR
31881@end smallexample
31882
31883Disassemble the whole @code{main} function. Line 32 is part of
31884@code{main}.
31885
31886@smallexample
31887-data-disassemble -f basics.c -l 32 -- 0
31888^done,asm_insns=[
31889@{address="0x000107bc",func-name="main",offset="0",
31890inst="save %sp, -112, %sp"@},
31891@{address="0x000107c0",func-name="main",offset="4",
31892inst="mov 2, %o0"@},
31893@{address="0x000107c4",func-name="main",offset="8",
31894inst="sethi %hi(0x11800), %o2"@},
31895[@dots{}]
31896@{address="0x0001081c",func-name="main",offset="96",inst="ret "@},
31897@{address="0x00010820",func-name="main",offset="100",inst="restore "@}]
594fe323 31898(gdb)
922fbb7b
AC
31899@end smallexample
31900
a2c02241 31901Disassemble 3 instructions from the start of @code{main}:
922fbb7b 31902
a2c02241 31903@smallexample
594fe323 31904(gdb)
a2c02241
NR
31905-data-disassemble -f basics.c -l 32 -n 3 -- 0
31906^done,asm_insns=[
31907@{address="0x000107bc",func-name="main",offset="0",
31908inst="save %sp, -112, %sp"@},
31909@{address="0x000107c0",func-name="main",offset="4",
31910inst="mov 2, %o0"@},
31911@{address="0x000107c4",func-name="main",offset="8",
31912inst="sethi %hi(0x11800), %o2"@}]
594fe323 31913(gdb)
a2c02241
NR
31914@end smallexample
31915
31916Disassemble 3 instructions from the start of @code{main} in mixed mode:
31917
31918@smallexample
594fe323 31919(gdb)
a2c02241
NR
31920-data-disassemble -f basics.c -l 32 -n 3 -- 1
31921^done,asm_insns=[
31922src_and_asm_line=@{line="31",
ed8a1c2d
AB
31923file="../../../src/gdb/testsuite/gdb.mi/basics.c",
31924fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c",
31925line_asm_insn=[@{address="0x000107bc",
31926func-name="main",offset="0",inst="save %sp, -112, %sp"@}]@},
a2c02241 31927src_and_asm_line=@{line="32",
ed8a1c2d
AB
31928file="../../../src/gdb/testsuite/gdb.mi/basics.c",
31929fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c",
31930line_asm_insn=[@{address="0x000107c0",
31931func-name="main",offset="4",inst="mov 2, %o0"@},
a2c02241
NR
31932@{address="0x000107c4",func-name="main",offset="8",
31933inst="sethi %hi(0x11800), %o2"@}]@}]
594fe323 31934(gdb)
a2c02241
NR
31935@end smallexample
31936
31937
31938@subheading The @code{-data-evaluate-expression} Command
31939@findex -data-evaluate-expression
922fbb7b
AC
31940
31941@subsubheading Synopsis
31942
31943@smallexample
a2c02241 31944 -data-evaluate-expression @var{expr}
922fbb7b
AC
31945@end smallexample
31946
a2c02241
NR
31947Evaluate @var{expr} as an expression. The expression could contain an
31948inferior function call. The function call will execute synchronously.
31949If the expression contains spaces, it must be enclosed in double quotes.
922fbb7b
AC
31950
31951@subsubheading @value{GDBN} Command
31952
a2c02241
NR
31953The corresponding @value{GDBN} commands are @samp{print}, @samp{output}, and
31954@samp{call}. In @code{gdbtk} only, there's a corresponding
31955@samp{gdb_eval} command.
922fbb7b
AC
31956
31957@subsubheading Example
31958
a2c02241
NR
31959In the following example, the numbers that precede the commands are the
31960@dfn{tokens} described in @ref{GDB/MI Command Syntax, ,@sc{gdb/mi}
31961Command Syntax}. Notice how @sc{gdb/mi} returns the same tokens in its
31962output.
31963
922fbb7b 31964@smallexample
a2c02241
NR
31965211-data-evaluate-expression A
31966211^done,value="1"
594fe323 31967(gdb)
a2c02241
NR
31968311-data-evaluate-expression &A
31969311^done,value="0xefffeb7c"
594fe323 31970(gdb)
a2c02241
NR
31971411-data-evaluate-expression A+3
31972411^done,value="4"
594fe323 31973(gdb)
a2c02241
NR
31974511-data-evaluate-expression "A + 3"
31975511^done,value="4"
594fe323 31976(gdb)
a2c02241 31977@end smallexample
922fbb7b
AC
31978
31979
a2c02241
NR
31980@subheading The @code{-data-list-changed-registers} Command
31981@findex -data-list-changed-registers
922fbb7b
AC
31982
31983@subsubheading Synopsis
31984
31985@smallexample
a2c02241 31986 -data-list-changed-registers
922fbb7b
AC
31987@end smallexample
31988
a2c02241 31989Display a list of the registers that have changed.
922fbb7b
AC
31990
31991@subsubheading @value{GDBN} Command
31992
a2c02241
NR
31993@value{GDBN} doesn't have a direct analog for this command; @code{gdbtk}
31994has the corresponding command @samp{gdb_changed_register_list}.
922fbb7b
AC
31995
31996@subsubheading Example
922fbb7b 31997
a2c02241 31998On a PPC MBX board:
922fbb7b
AC
31999
32000@smallexample
594fe323 32001(gdb)
a2c02241
NR
32002-exec-continue
32003^running
922fbb7b 32004
594fe323 32005(gdb)
a47ec5fe
AR
32006*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame=@{
32007func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c",
6d52907e 32008line="5",arch="powerpc"@}
594fe323 32009(gdb)
a2c02241
NR
32010-data-list-changed-registers
32011^done,changed-registers=["0","1","2","4","5","6","7","8","9",
32012"10","11","13","14","15","16","17","18","19","20","21","22","23",
32013"24","25","26","27","28","30","31","64","65","66","67","69"]
594fe323 32014(gdb)
a2c02241 32015@end smallexample
922fbb7b
AC
32016
32017
a2c02241
NR
32018@subheading The @code{-data-list-register-names} Command
32019@findex -data-list-register-names
922fbb7b
AC
32020
32021@subsubheading Synopsis
32022
32023@smallexample
a2c02241 32024 -data-list-register-names [ ( @var{regno} )+ ]
922fbb7b
AC
32025@end smallexample
32026
a2c02241
NR
32027Show a list of register names for the current target. If no arguments
32028are given, it shows a list of the names of all the registers. If
32029integer numbers are given as arguments, it will print a list of the
32030names of the registers corresponding to the arguments. To ensure
32031consistency between a register name and its number, the output list may
32032include empty register names.
922fbb7b
AC
32033
32034@subsubheading @value{GDBN} Command
32035
a2c02241
NR
32036@value{GDBN} does not have a command which corresponds to
32037@samp{-data-list-register-names}. In @code{gdbtk} there is a
32038corresponding command @samp{gdb_regnames}.
922fbb7b
AC
32039
32040@subsubheading Example
922fbb7b 32041
a2c02241
NR
32042For the PPC MBX board:
32043@smallexample
594fe323 32044(gdb)
a2c02241
NR
32045-data-list-register-names
32046^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
32047"r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
32048"r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
32049"r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
32050"f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
32051"f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
32052"", "pc","ps","cr","lr","ctr","xer"]
594fe323 32053(gdb)
a2c02241
NR
32054-data-list-register-names 1 2 3
32055^done,register-names=["r1","r2","r3"]
594fe323 32056(gdb)
a2c02241 32057@end smallexample
922fbb7b 32058
a2c02241
NR
32059@subheading The @code{-data-list-register-values} Command
32060@findex -data-list-register-values
922fbb7b
AC
32061
32062@subsubheading Synopsis
32063
32064@smallexample
c898adb7
YQ
32065 -data-list-register-values
32066 [ @code{--skip-unavailable} ] @var{fmt} [ ( @var{regno} )*]
922fbb7b
AC
32067@end smallexample
32068
697aa1b7
EZ
32069Display the registers' contents. The format according to which the
32070registers' contents are to be returned is given by @var{fmt}, followed
32071by an optional list of numbers specifying the registers to display. A
32072missing list of numbers indicates that the contents of all the
32073registers must be returned. The @code{--skip-unavailable} option
32074indicates that only the available registers are to be returned.
a2c02241
NR
32075
32076Allowed formats for @var{fmt} are:
32077
32078@table @code
32079@item x
32080Hexadecimal
32081@item o
32082Octal
32083@item t
32084Binary
32085@item d
32086Decimal
32087@item r
32088Raw
32089@item N
32090Natural
32091@end table
922fbb7b
AC
32092
32093@subsubheading @value{GDBN} Command
32094
a2c02241
NR
32095The corresponding @value{GDBN} commands are @samp{info reg}, @samp{info
32096all-reg}, and (in @code{gdbtk}) @samp{gdb_fetch_registers}.
922fbb7b
AC
32097
32098@subsubheading Example
922fbb7b 32099
a2c02241
NR
32100For a PPC MBX board (note: line breaks are for readability only, they
32101don't appear in the actual output):
32102
32103@smallexample
594fe323 32104(gdb)
a2c02241
NR
32105-data-list-register-values r 64 65
32106^done,register-values=[@{number="64",value="0xfe00a300"@},
32107@{number="65",value="0x00029002"@}]
594fe323 32108(gdb)
a2c02241
NR
32109-data-list-register-values x
32110^done,register-values=[@{number="0",value="0xfe0043c8"@},
32111@{number="1",value="0x3fff88"@},@{number="2",value="0xfffffffe"@},
32112@{number="3",value="0x0"@},@{number="4",value="0xa"@},
32113@{number="5",value="0x3fff68"@},@{number="6",value="0x3fff58"@},
32114@{number="7",value="0xfe011e98"@},@{number="8",value="0x2"@},
32115@{number="9",value="0xfa202820"@},@{number="10",value="0xfa202808"@},
32116@{number="11",value="0x1"@},@{number="12",value="0x0"@},
32117@{number="13",value="0x4544"@},@{number="14",value="0xffdfffff"@},
32118@{number="15",value="0xffffffff"@},@{number="16",value="0xfffffeff"@},
32119@{number="17",value="0xefffffed"@},@{number="18",value="0xfffffffe"@},
32120@{number="19",value="0xffffffff"@},@{number="20",value="0xffffffff"@},
32121@{number="21",value="0xffffffff"@},@{number="22",value="0xfffffff7"@},
32122@{number="23",value="0xffffffff"@},@{number="24",value="0xffffffff"@},
32123@{number="25",value="0xffffffff"@},@{number="26",value="0xfffffffb"@},
32124@{number="27",value="0xffffffff"@},@{number="28",value="0xf7bfffff"@},
32125@{number="29",value="0x0"@},@{number="30",value="0xfe010000"@},
32126@{number="31",value="0x0"@},@{number="32",value="0x0"@},
32127@{number="33",value="0x0"@},@{number="34",value="0x0"@},
32128@{number="35",value="0x0"@},@{number="36",value="0x0"@},
32129@{number="37",value="0x0"@},@{number="38",value="0x0"@},
32130@{number="39",value="0x0"@},@{number="40",value="0x0"@},
32131@{number="41",value="0x0"@},@{number="42",value="0x0"@},
32132@{number="43",value="0x0"@},@{number="44",value="0x0"@},
32133@{number="45",value="0x0"@},@{number="46",value="0x0"@},
32134@{number="47",value="0x0"@},@{number="48",value="0x0"@},
32135@{number="49",value="0x0"@},@{number="50",value="0x0"@},
32136@{number="51",value="0x0"@},@{number="52",value="0x0"@},
32137@{number="53",value="0x0"@},@{number="54",value="0x0"@},
32138@{number="55",value="0x0"@},@{number="56",value="0x0"@},
32139@{number="57",value="0x0"@},@{number="58",value="0x0"@},
32140@{number="59",value="0x0"@},@{number="60",value="0x0"@},
32141@{number="61",value="0x0"@},@{number="62",value="0x0"@},
32142@{number="63",value="0x0"@},@{number="64",value="0xfe00a300"@},
32143@{number="65",value="0x29002"@},@{number="66",value="0x202f04b5"@},
32144@{number="67",value="0xfe0043b0"@},@{number="68",value="0xfe00b3e4"@},
32145@{number="69",value="0x20002b03"@}]
594fe323 32146(gdb)
a2c02241 32147@end smallexample
922fbb7b 32148
a2c02241
NR
32149
32150@subheading The @code{-data-read-memory} Command
32151@findex -data-read-memory
922fbb7b 32152
8dedea02
VP
32153This command is deprecated, use @code{-data-read-memory-bytes} instead.
32154
922fbb7b
AC
32155@subsubheading Synopsis
32156
32157@smallexample
a2c02241
NR
32158 -data-read-memory [ -o @var{byte-offset} ]
32159 @var{address} @var{word-format} @var{word-size}
32160 @var{nr-rows} @var{nr-cols} [ @var{aschar} ]
922fbb7b
AC
32161@end smallexample
32162
a2c02241
NR
32163@noindent
32164where:
922fbb7b 32165
a2c02241
NR
32166@table @samp
32167@item @var{address}
32168An expression specifying the address of the first memory word to be
32169read. Complex expressions containing embedded white space should be
32170quoted using the C convention.
922fbb7b 32171
a2c02241
NR
32172@item @var{word-format}
32173The format to be used to print the memory words. The notation is the
32174same as for @value{GDBN}'s @code{print} command (@pxref{Output Formats,
79a6e687 32175,Output Formats}).
922fbb7b 32176
a2c02241
NR
32177@item @var{word-size}
32178The size of each memory word in bytes.
922fbb7b 32179
a2c02241
NR
32180@item @var{nr-rows}
32181The number of rows in the output table.
922fbb7b 32182
a2c02241
NR
32183@item @var{nr-cols}
32184The number of columns in the output table.
922fbb7b 32185
a2c02241
NR
32186@item @var{aschar}
32187If present, indicates that each row should include an @sc{ascii} dump. The
32188value of @var{aschar} is used as a padding character when a byte is not a
32189member of the printable @sc{ascii} character set (printable @sc{ascii}
32190characters are those whose code is between 32 and 126, inclusively).
922fbb7b 32191
a2c02241
NR
32192@item @var{byte-offset}
32193An offset to add to the @var{address} before fetching memory.
32194@end table
922fbb7b 32195
a2c02241
NR
32196This command displays memory contents as a table of @var{nr-rows} by
32197@var{nr-cols} words, each word being @var{word-size} bytes. In total,
32198@code{@var{nr-rows} * @var{nr-cols} * @var{word-size}} bytes are read
32199(returned as @samp{total-bytes}). Should less than the requested number
32200of bytes be returned by the target, the missing words are identified
32201using @samp{N/A}. The number of bytes read from the target is returned
32202in @samp{nr-bytes} and the starting address used to read memory in
32203@samp{addr}.
32204
32205The address of the next/previous row or page is available in
32206@samp{next-row} and @samp{prev-row}, @samp{next-page} and
32207@samp{prev-page}.
922fbb7b
AC
32208
32209@subsubheading @value{GDBN} Command
32210
a2c02241
NR
32211The corresponding @value{GDBN} command is @samp{x}. @code{gdbtk} has
32212@samp{gdb_get_mem} memory read command.
922fbb7b
AC
32213
32214@subsubheading Example
32e7087d 32215
a2c02241
NR
32216Read six bytes of memory starting at @code{bytes+6} but then offset by
32217@code{-6} bytes. Format as three rows of two columns. One byte per
32218word. Display each word in hex.
32e7087d
JB
32219
32220@smallexample
594fe323 32221(gdb)
a2c02241
NR
322229-data-read-memory -o -6 -- bytes+6 x 1 3 2
322239^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
32224next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
32225prev-page="0x0000138a",memory=[
32226@{addr="0x00001390",data=["0x00","0x01"]@},
32227@{addr="0x00001392",data=["0x02","0x03"]@},
32228@{addr="0x00001394",data=["0x04","0x05"]@}]
594fe323 32229(gdb)
32e7087d
JB
32230@end smallexample
32231
a2c02241
NR
32232Read two bytes of memory starting at address @code{shorts + 64} and
32233display as a single word formatted in decimal.
32e7087d 32234
32e7087d 32235@smallexample
594fe323 32236(gdb)
a2c02241
NR
322375-data-read-memory shorts+64 d 2 1 1
322385^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
32239next-row="0x00001512",prev-row="0x0000150e",
32240next-page="0x00001512",prev-page="0x0000150e",memory=[
32241@{addr="0x00001510",data=["128"]@}]
594fe323 32242(gdb)
32e7087d
JB
32243@end smallexample
32244
a2c02241
NR
32245Read thirty two bytes of memory starting at @code{bytes+16} and format
32246as eight rows of four columns. Include a string encoding with @samp{x}
32247used as the non-printable character.
922fbb7b
AC
32248
32249@smallexample
594fe323 32250(gdb)
a2c02241
NR
322514-data-read-memory bytes+16 x 1 8 4 x
322524^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
32253next-row="0x000013c0",prev-row="0x0000139c",
32254next-page="0x000013c0",prev-page="0x00001380",memory=[
32255@{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"@},
32256@{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"@},
32257@{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"@},
32258@{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"@},
32259@{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"@},
32260@{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"@},
32261@{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"@},
32262@{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"@}]
594fe323 32263(gdb)
922fbb7b
AC
32264@end smallexample
32265
8dedea02
VP
32266@subheading The @code{-data-read-memory-bytes} Command
32267@findex -data-read-memory-bytes
32268
32269@subsubheading Synopsis
32270
32271@smallexample
a86c90e6 32272 -data-read-memory-bytes [ -o @var{offset} ]
8dedea02
VP
32273 @var{address} @var{count}
32274@end smallexample
32275
32276@noindent
32277where:
32278
32279@table @samp
32280@item @var{address}
a86c90e6
SM
32281An expression specifying the address of the first addressable memory unit
32282to be read. Complex expressions containing embedded white space should be
8dedea02
VP
32283quoted using the C convention.
32284
32285@item @var{count}
a86c90e6
SM
32286The number of addressable memory units to read. This should be an integer
32287literal.
8dedea02 32288
a86c90e6
SM
32289@item @var{offset}
32290The offset relative to @var{address} at which to start reading. This
32291should be an integer literal. This option is provided so that a frontend
32292is not required to first evaluate address and then perform address
32293arithmetics itself.
8dedea02
VP
32294
32295@end table
32296
32297This command attempts to read all accessible memory regions in the
32298specified range. First, all regions marked as unreadable in the memory
32299map (if one is defined) will be skipped. @xref{Memory Region
32300Attributes}. Second, @value{GDBN} will attempt to read the remaining
32301regions. For each one, if reading full region results in an errors,
32302@value{GDBN} will try to read a subset of the region.
32303
a86c90e6
SM
32304In general, every single memory unit in the region may be readable or not,
32305and the only way to read every readable unit is to try a read at
8dedea02 32306every address, which is not practical. Therefore, @value{GDBN} will
a86c90e6 32307attempt to read all accessible memory units at either beginning or the end
8dedea02
VP
32308of the region, using a binary division scheme. This heuristic works
32309well for reading accross a memory map boundary. Note that if a region
32310has a readable range that is neither at the beginning or the end,
32311@value{GDBN} will not read it.
32312
32313The result record (@pxref{GDB/MI Result Records}) that is output of
32314the command includes a field named @samp{memory} whose content is a
32315list of tuples. Each tuple represent a successfully read memory block
32316and has the following fields:
32317
32318@table @code
32319@item begin
32320The start address of the memory block, as hexadecimal literal.
32321
32322@item end
32323The end address of the memory block, as hexadecimal literal.
32324
32325@item offset
32326The offset of the memory block, as hexadecimal literal, relative to
32327the start address passed to @code{-data-read-memory-bytes}.
32328
32329@item contents
32330The contents of the memory block, in hex.
32331
32332@end table
32333
32334
32335
32336@subsubheading @value{GDBN} Command
32337
32338The corresponding @value{GDBN} command is @samp{x}.
32339
32340@subsubheading Example
32341
32342@smallexample
32343(gdb)
32344-data-read-memory-bytes &a 10
32345^done,memory=[@{begin="0xbffff154",offset="0x00000000",
32346 end="0xbffff15e",
32347 contents="01000000020000000300"@}]
32348(gdb)
32349@end smallexample
32350
32351
32352@subheading The @code{-data-write-memory-bytes} Command
32353@findex -data-write-memory-bytes
32354
32355@subsubheading Synopsis
32356
32357@smallexample
32358 -data-write-memory-bytes @var{address} @var{contents}
62747a60 32359 -data-write-memory-bytes @var{address} @var{contents} @r{[}@var{count}@r{]}
8dedea02
VP
32360@end smallexample
32361
32362@noindent
32363where:
32364
32365@table @samp
32366@item @var{address}
a86c90e6
SM
32367An expression specifying the address of the first addressable memory unit
32368to be written. Complex expressions containing embedded white space should
32369be quoted using the C convention.
8dedea02
VP
32370
32371@item @var{contents}
a86c90e6
SM
32372The hex-encoded data to write. It is an error if @var{contents} does
32373not represent an integral number of addressable memory units.
8dedea02 32374
62747a60 32375@item @var{count}
a86c90e6
SM
32376Optional argument indicating the number of addressable memory units to be
32377written. If @var{count} is greater than @var{contents}' length,
32378@value{GDBN} will repeatedly write @var{contents} until it fills
32379@var{count} memory units.
62747a60 32380
8dedea02
VP
32381@end table
32382
32383@subsubheading @value{GDBN} Command
32384
32385There's no corresponding @value{GDBN} command.
32386
32387@subsubheading Example
32388
32389@smallexample
32390(gdb)
32391-data-write-memory-bytes &a "aabbccdd"
32392^done
32393(gdb)
32394@end smallexample
32395
62747a60
TT
32396@smallexample
32397(gdb)
32398-data-write-memory-bytes &a "aabbccdd" 16e
32399^done
32400(gdb)
32401@end smallexample
8dedea02 32402
a2c02241
NR
32403@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
32404@node GDB/MI Tracepoint Commands
32405@section @sc{gdb/mi} Tracepoint Commands
922fbb7b 32406
18148017
VP
32407The commands defined in this section implement MI support for
32408tracepoints. For detailed introduction, see @ref{Tracepoints}.
32409
32410@subheading The @code{-trace-find} Command
32411@findex -trace-find
32412
32413@subsubheading Synopsis
32414
32415@smallexample
32416 -trace-find @var{mode} [@var{parameters}@dots{}]
32417@end smallexample
32418
32419Find a trace frame using criteria defined by @var{mode} and
32420@var{parameters}. The following table lists permissible
32421modes and their parameters. For details of operation, see @ref{tfind}.
32422
32423@table @samp
32424
32425@item none
32426No parameters are required. Stops examining trace frames.
32427
32428@item frame-number
32429An integer is required as parameter. Selects tracepoint frame with
32430that index.
32431
32432@item tracepoint-number
32433An integer is required as parameter. Finds next
32434trace frame that corresponds to tracepoint with the specified number.
32435
32436@item pc
32437An address is required as parameter. Finds
32438next trace frame that corresponds to any tracepoint at the specified
32439address.
32440
32441@item pc-inside-range
32442Two addresses are required as parameters. Finds next trace
32443frame that corresponds to a tracepoint at an address inside the
32444specified range. Both bounds are considered to be inside the range.
32445
32446@item pc-outside-range
32447Two addresses are required as parameters. Finds
32448next trace frame that corresponds to a tracepoint at an address outside
32449the specified range. Both bounds are considered to be inside the range.
32450
32451@item line
32452Line specification is required as parameter. @xref{Specify Location}.
32453Finds next trace frame that corresponds to a tracepoint at
32454the specified location.
32455
32456@end table
32457
32458If @samp{none} was passed as @var{mode}, the response does not
32459have fields. Otherwise, the response may have the following fields:
32460
32461@table @samp
32462@item found
32463This field has either @samp{0} or @samp{1} as the value, depending
32464on whether a matching tracepoint was found.
32465
32466@item traceframe
32467The index of the found traceframe. This field is present iff
32468the @samp{found} field has value of @samp{1}.
32469
32470@item tracepoint
32471The index of the found tracepoint. This field is present iff
32472the @samp{found} field has value of @samp{1}.
32473
32474@item frame
32475The information about the frame corresponding to the found trace
32476frame. This field is present only if a trace frame was found.
cd64ee31 32477@xref{GDB/MI Frame Information}, for description of this field.
18148017
VP
32478
32479@end table
32480
7d13fe92
SS
32481@subsubheading @value{GDBN} Command
32482
32483The corresponding @value{GDBN} command is @samp{tfind}.
32484
18148017
VP
32485@subheading -trace-define-variable
32486@findex -trace-define-variable
32487
32488@subsubheading Synopsis
32489
32490@smallexample
32491 -trace-define-variable @var{name} [ @var{value} ]
32492@end smallexample
32493
32494Create trace variable @var{name} if it does not exist. If
32495@var{value} is specified, sets the initial value of the specified
32496trace variable to that value. Note that the @var{name} should start
32497with the @samp{$} character.
32498
7d13fe92
SS
32499@subsubheading @value{GDBN} Command
32500
32501The corresponding @value{GDBN} command is @samp{tvariable}.
32502
dc673c81
YQ
32503@subheading The @code{-trace-frame-collected} Command
32504@findex -trace-frame-collected
32505
32506@subsubheading Synopsis
32507
32508@smallexample
32509 -trace-frame-collected
32510 [--var-print-values @var{var_pval}]
32511 [--comp-print-values @var{comp_pval}]
32512 [--registers-format @var{regformat}]
32513 [--memory-contents]
32514@end smallexample
32515
32516This command returns the set of collected objects, register names,
32517trace state variable names, memory ranges and computed expressions
32518that have been collected at a particular trace frame. The optional
32519parameters to the command affect the output format in different ways.
32520See the output description table below for more details.
32521
32522The reported names can be used in the normal manner to create
32523varobjs and inspect the objects themselves. The items returned by
32524this command are categorized so that it is clear which is a variable,
32525which is a register, which is a trace state variable, which is a
32526memory range and which is a computed expression.
32527
32528For instance, if the actions were
32529@smallexample
32530collect myVar, myArray[myIndex], myObj.field, myPtr->field, myCount + 2
32531collect *(int*)0xaf02bef0@@40
32532@end smallexample
32533
32534@noindent
32535the object collected in its entirety would be @code{myVar}. The
32536object @code{myArray} would be partially collected, because only the
32537element at index @code{myIndex} would be collected. The remaining
32538objects would be computed expressions.
32539
32540An example output would be:
32541
32542@smallexample
32543(gdb)
32544-trace-frame-collected
32545^done,
32546 explicit-variables=[@{name="myVar",value="1"@}],
32547 computed-expressions=[@{name="myArray[myIndex]",value="0"@},
32548 @{name="myObj.field",value="0"@},
32549 @{name="myPtr->field",value="1"@},
32550 @{name="myCount + 2",value="3"@},
32551 @{name="$tvar1 + 1",value="43970027"@}],
32552 registers=[@{number="0",value="0x7fe2c6e79ec8"@},
32553 @{number="1",value="0x0"@},
32554 @{number="2",value="0x4"@},
32555 ...
32556 @{number="125",value="0x0"@}],
32557 tvars=[@{name="$tvar1",current="43970026"@}],
32558 memory=[@{address="0x0000000000602264",length="4"@},
32559 @{address="0x0000000000615bc0",length="4"@}]
32560(gdb)
32561@end smallexample
32562
32563Where:
32564
32565@table @code
32566@item explicit-variables
32567The set of objects that have been collected in their entirety (as
32568opposed to collecting just a few elements of an array or a few struct
32569members). For each object, its name and value are printed.
32570The @code{--var-print-values} option affects how or whether the value
32571field is output. If @var{var_pval} is 0, then print only the names;
32572if it is 1, print also their values; and if it is 2, print the name,
32573type and value for simple data types, and the name and type for
32574arrays, structures and unions.
32575
32576@item computed-expressions
32577The set of computed expressions that have been collected at the
32578current trace frame. The @code{--comp-print-values} option affects
32579this set like the @code{--var-print-values} option affects the
32580@code{explicit-variables} set. See above.
32581
32582@item registers
32583The registers that have been collected at the current trace frame.
32584For each register collected, the name and current value are returned.
32585The value is formatted according to the @code{--registers-format}
32586option. See the @command{-data-list-register-values} command for a
32587list of the allowed formats. The default is @samp{x}.
32588
32589@item tvars
32590The trace state variables that have been collected at the current
32591trace frame. For each trace state variable collected, the name and
32592current value are returned.
32593
32594@item memory
32595The set of memory ranges that have been collected at the current trace
32596frame. Its content is a list of tuples. Each tuple represents a
32597collected memory range and has the following fields:
32598
32599@table @code
32600@item address
32601The start address of the memory range, as hexadecimal literal.
32602
32603@item length
32604The length of the memory range, as decimal literal.
32605
32606@item contents
32607The contents of the memory block, in hex. This field is only present
32608if the @code{--memory-contents} option is specified.
32609
32610@end table
32611
32612@end table
32613
32614@subsubheading @value{GDBN} Command
32615
32616There is no corresponding @value{GDBN} command.
32617
32618@subsubheading Example
32619
18148017
VP
32620@subheading -trace-list-variables
32621@findex -trace-list-variables
922fbb7b 32622
18148017 32623@subsubheading Synopsis
922fbb7b 32624
18148017
VP
32625@smallexample
32626 -trace-list-variables
32627@end smallexample
922fbb7b 32628
18148017
VP
32629Return a table of all defined trace variables. Each element of the
32630table has the following fields:
922fbb7b 32631
18148017
VP
32632@table @samp
32633@item name
32634The name of the trace variable. This field is always present.
922fbb7b 32635
18148017
VP
32636@item initial
32637The initial value. This is a 64-bit signed integer. This
32638field is always present.
922fbb7b 32639
18148017
VP
32640@item current
32641The value the trace variable has at the moment. This is a 64-bit
32642signed integer. This field is absent iff current value is
32643not defined, for example if the trace was never run, or is
32644presently running.
922fbb7b 32645
18148017 32646@end table
922fbb7b 32647
7d13fe92
SS
32648@subsubheading @value{GDBN} Command
32649
32650The corresponding @value{GDBN} command is @samp{tvariables}.
32651
18148017 32652@subsubheading Example
922fbb7b 32653
18148017
VP
32654@smallexample
32655(gdb)
32656-trace-list-variables
32657^done,trace-variables=@{nr_rows="1",nr_cols="3",
32658hdr=[@{width="15",alignment="-1",col_name="name",colhdr="Name"@},
32659 @{width="11",alignment="-1",col_name="initial",colhdr="Initial"@},
32660 @{width="11",alignment="-1",col_name="current",colhdr="Current"@}],
32661body=[variable=@{name="$trace_timestamp",initial="0"@}
32662 variable=@{name="$foo",initial="10",current="15"@}]@}
32663(gdb)
32664@end smallexample
922fbb7b 32665
18148017
VP
32666@subheading -trace-save
32667@findex -trace-save
922fbb7b 32668
18148017
VP
32669@subsubheading Synopsis
32670
32671@smallexample
99e61eda 32672 -trace-save [ -r ] [ -ctf ] @var{filename}
18148017
VP
32673@end smallexample
32674
32675Saves the collected trace data to @var{filename}. Without the
32676@samp{-r} option, the data is downloaded from the target and saved
32677in a local file. With the @samp{-r} option the target is asked
32678to perform the save.
32679
99e61eda
SM
32680By default, this command will save the trace in the tfile format. You can
32681supply the optional @samp{-ctf} argument to save it the CTF format. See
32682@ref{Trace Files} for more information about CTF.
32683
7d13fe92
SS
32684@subsubheading @value{GDBN} Command
32685
32686The corresponding @value{GDBN} command is @samp{tsave}.
32687
18148017
VP
32688
32689@subheading -trace-start
32690@findex -trace-start
32691
32692@subsubheading Synopsis
32693
32694@smallexample
32695 -trace-start
32696@end smallexample
922fbb7b 32697
be06ba8c 32698Starts a tracing experiment. The result of this command does not
18148017 32699have any fields.
922fbb7b 32700
7d13fe92
SS
32701@subsubheading @value{GDBN} Command
32702
32703The corresponding @value{GDBN} command is @samp{tstart}.
32704
18148017
VP
32705@subheading -trace-status
32706@findex -trace-status
922fbb7b 32707
18148017
VP
32708@subsubheading Synopsis
32709
32710@smallexample
32711 -trace-status
32712@end smallexample
32713
a97153c7 32714Obtains the status of a tracing experiment. The result may include
18148017
VP
32715the following fields:
32716
32717@table @samp
32718
32719@item supported
32720May have a value of either @samp{0}, when no tracing operations are
32721supported, @samp{1}, when all tracing operations are supported, or
32722@samp{file} when examining trace file. In the latter case, examining
32723of trace frame is possible but new tracing experiement cannot be
32724started. This field is always present.
32725
32726@item running
32727May have a value of either @samp{0} or @samp{1} depending on whether
32728tracing experiement is in progress on target. This field is present
32729if @samp{supported} field is not @samp{0}.
32730
32731@item stop-reason
32732Report the reason why the tracing was stopped last time. This field
32733may be absent iff tracing was never stopped on target yet. The
32734value of @samp{request} means the tracing was stopped as result of
32735the @code{-trace-stop} command. The value of @samp{overflow} means
32736the tracing buffer is full. The value of @samp{disconnection} means
32737tracing was automatically stopped when @value{GDBN} has disconnected.
32738The value of @samp{passcount} means tracing was stopped when a
32739tracepoint was passed a maximal number of times for that tracepoint.
32740This field is present if @samp{supported} field is not @samp{0}.
32741
32742@item stopping-tracepoint
32743The number of tracepoint whose passcount as exceeded. This field is
32744present iff the @samp{stop-reason} field has the value of
32745@samp{passcount}.
32746
32747@item frames
87290684
SS
32748@itemx frames-created
32749The @samp{frames} field is a count of the total number of trace frames
32750in the trace buffer, while @samp{frames-created} is the total created
32751during the run, including ones that were discarded, such as when a
32752circular trace buffer filled up. Both fields are optional.
18148017
VP
32753
32754@item buffer-size
32755@itemx buffer-free
32756These fields tell the current size of the tracing buffer and the
87290684 32757remaining space. These fields are optional.
18148017 32758
a97153c7
PA
32759@item circular
32760The value of the circular trace buffer flag. @code{1} means that the
32761trace buffer is circular and old trace frames will be discarded if
32762necessary to make room, @code{0} means that the trace buffer is linear
32763and may fill up.
32764
32765@item disconnected
32766The value of the disconnected tracing flag. @code{1} means that
32767tracing will continue after @value{GDBN} disconnects, @code{0} means
32768that the trace run will stop.
32769
f5911ea1
HAQ
32770@item trace-file
32771The filename of the trace file being examined. This field is
32772optional, and only present when examining a trace file.
32773
18148017
VP
32774@end table
32775
7d13fe92
SS
32776@subsubheading @value{GDBN} Command
32777
32778The corresponding @value{GDBN} command is @samp{tstatus}.
32779
18148017
VP
32780@subheading -trace-stop
32781@findex -trace-stop
32782
32783@subsubheading Synopsis
32784
32785@smallexample
32786 -trace-stop
32787@end smallexample
922fbb7b 32788
18148017
VP
32789Stops a tracing experiment. The result of this command has the same
32790fields as @code{-trace-status}, except that the @samp{supported} and
32791@samp{running} fields are not output.
922fbb7b 32792
7d13fe92
SS
32793@subsubheading @value{GDBN} Command
32794
32795The corresponding @value{GDBN} command is @samp{tstop}.
32796
922fbb7b 32797
a2c02241
NR
32798@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
32799@node GDB/MI Symbol Query
32800@section @sc{gdb/mi} Symbol Query Commands
922fbb7b
AC
32801
32802
9901a55b 32803@ignore
a2c02241
NR
32804@subheading The @code{-symbol-info-address} Command
32805@findex -symbol-info-address
922fbb7b
AC
32806
32807@subsubheading Synopsis
32808
32809@smallexample
a2c02241 32810 -symbol-info-address @var{symbol}
922fbb7b
AC
32811@end smallexample
32812
a2c02241 32813Describe where @var{symbol} is stored.
922fbb7b
AC
32814
32815@subsubheading @value{GDBN} Command
32816
a2c02241 32817The corresponding @value{GDBN} command is @samp{info address}.
922fbb7b
AC
32818
32819@subsubheading Example
32820N.A.
32821
32822
a2c02241
NR
32823@subheading The @code{-symbol-info-file} Command
32824@findex -symbol-info-file
922fbb7b
AC
32825
32826@subsubheading Synopsis
32827
32828@smallexample
a2c02241 32829 -symbol-info-file
922fbb7b
AC
32830@end smallexample
32831
a2c02241 32832Show the file for the symbol.
922fbb7b 32833
a2c02241 32834@subsubheading @value{GDBN} Command
922fbb7b 32835
a2c02241
NR
32836There's no equivalent @value{GDBN} command. @code{gdbtk} has
32837@samp{gdb_find_file}.
922fbb7b
AC
32838
32839@subsubheading Example
32840N.A.
32841
32842
a2c02241
NR
32843@subheading The @code{-symbol-info-function} Command
32844@findex -symbol-info-function
922fbb7b
AC
32845
32846@subsubheading Synopsis
32847
32848@smallexample
a2c02241 32849 -symbol-info-function
922fbb7b
AC
32850@end smallexample
32851
a2c02241 32852Show which function the symbol lives in.
922fbb7b
AC
32853
32854@subsubheading @value{GDBN} Command
32855
a2c02241 32856@samp{gdb_get_function} in @code{gdbtk}.
922fbb7b
AC
32857
32858@subsubheading Example
32859N.A.
32860
32861
a2c02241
NR
32862@subheading The @code{-symbol-info-line} Command
32863@findex -symbol-info-line
922fbb7b
AC
32864
32865@subsubheading Synopsis
32866
32867@smallexample
a2c02241 32868 -symbol-info-line
922fbb7b
AC
32869@end smallexample
32870
a2c02241 32871Show the core addresses of the code for a source line.
922fbb7b 32872
a2c02241 32873@subsubheading @value{GDBN} Command
922fbb7b 32874
a2c02241
NR
32875The corresponding @value{GDBN} command is @samp{info line}.
32876@code{gdbtk} has the @samp{gdb_get_line} and @samp{gdb_get_file} commands.
922fbb7b
AC
32877
32878@subsubheading Example
a2c02241 32879N.A.
922fbb7b
AC
32880
32881
a2c02241
NR
32882@subheading The @code{-symbol-info-symbol} Command
32883@findex -symbol-info-symbol
07f31aa6
DJ
32884
32885@subsubheading Synopsis
32886
a2c02241
NR
32887@smallexample
32888 -symbol-info-symbol @var{addr}
32889@end smallexample
07f31aa6 32890
a2c02241 32891Describe what symbol is at location @var{addr}.
07f31aa6 32892
a2c02241 32893@subsubheading @value{GDBN} Command
07f31aa6 32894
a2c02241 32895The corresponding @value{GDBN} command is @samp{info symbol}.
07f31aa6
DJ
32896
32897@subsubheading Example
a2c02241 32898N.A.
07f31aa6
DJ
32899
32900
a2c02241
NR
32901@subheading The @code{-symbol-list-functions} Command
32902@findex -symbol-list-functions
922fbb7b
AC
32903
32904@subsubheading Synopsis
32905
32906@smallexample
a2c02241 32907 -symbol-list-functions
922fbb7b
AC
32908@end smallexample
32909
a2c02241 32910List the functions in the executable.
922fbb7b
AC
32911
32912@subsubheading @value{GDBN} Command
32913
a2c02241
NR
32914@samp{info functions} in @value{GDBN}, @samp{gdb_listfunc} and
32915@samp{gdb_search} in @code{gdbtk}.
922fbb7b
AC
32916
32917@subsubheading Example
a2c02241 32918N.A.
9901a55b 32919@end ignore
922fbb7b
AC
32920
32921
a2c02241
NR
32922@subheading The @code{-symbol-list-lines} Command
32923@findex -symbol-list-lines
922fbb7b
AC
32924
32925@subsubheading Synopsis
32926
32927@smallexample
a2c02241 32928 -symbol-list-lines @var{filename}
922fbb7b
AC
32929@end smallexample
32930
a2c02241
NR
32931Print the list of lines that contain code and their associated program
32932addresses for the given source filename. The entries are sorted in
32933ascending PC order.
922fbb7b
AC
32934
32935@subsubheading @value{GDBN} Command
32936
a2c02241 32937There is no corresponding @value{GDBN} command.
922fbb7b
AC
32938
32939@subsubheading Example
a2c02241 32940@smallexample
594fe323 32941(gdb)
a2c02241
NR
32942-symbol-list-lines basics.c
32943^done,lines=[@{pc="0x08048554",line="7"@},@{pc="0x0804855a",line="8"@}]
594fe323 32944(gdb)
a2c02241 32945@end smallexample
922fbb7b
AC
32946
32947
9901a55b 32948@ignore
a2c02241
NR
32949@subheading The @code{-symbol-list-types} Command
32950@findex -symbol-list-types
922fbb7b
AC
32951
32952@subsubheading Synopsis
32953
32954@smallexample
a2c02241 32955 -symbol-list-types
922fbb7b
AC
32956@end smallexample
32957
a2c02241 32958List all the type names.
922fbb7b
AC
32959
32960@subsubheading @value{GDBN} Command
32961
a2c02241
NR
32962The corresponding commands are @samp{info types} in @value{GDBN},
32963@samp{gdb_search} in @code{gdbtk}.
922fbb7b
AC
32964
32965@subsubheading Example
32966N.A.
32967
32968
a2c02241
NR
32969@subheading The @code{-symbol-list-variables} Command
32970@findex -symbol-list-variables
922fbb7b
AC
32971
32972@subsubheading Synopsis
32973
32974@smallexample
a2c02241 32975 -symbol-list-variables
922fbb7b
AC
32976@end smallexample
32977
a2c02241 32978List all the global and static variable names.
922fbb7b
AC
32979
32980@subsubheading @value{GDBN} Command
32981
a2c02241 32982@samp{info variables} in @value{GDBN}, @samp{gdb_search} in @code{gdbtk}.
922fbb7b
AC
32983
32984@subsubheading Example
32985N.A.
32986
32987
a2c02241
NR
32988@subheading The @code{-symbol-locate} Command
32989@findex -symbol-locate
922fbb7b
AC
32990
32991@subsubheading Synopsis
32992
32993@smallexample
a2c02241 32994 -symbol-locate
922fbb7b
AC
32995@end smallexample
32996
922fbb7b
AC
32997@subsubheading @value{GDBN} Command
32998
a2c02241 32999@samp{gdb_loc} in @code{gdbtk}.
922fbb7b
AC
33000
33001@subsubheading Example
33002N.A.
33003
33004
a2c02241
NR
33005@subheading The @code{-symbol-type} Command
33006@findex -symbol-type
922fbb7b
AC
33007
33008@subsubheading Synopsis
33009
33010@smallexample
a2c02241 33011 -symbol-type @var{variable}
922fbb7b
AC
33012@end smallexample
33013
a2c02241 33014Show type of @var{variable}.
922fbb7b 33015
a2c02241 33016@subsubheading @value{GDBN} Command
922fbb7b 33017
a2c02241
NR
33018The corresponding @value{GDBN} command is @samp{ptype}, @code{gdbtk} has
33019@samp{gdb_obj_variable}.
33020
33021@subsubheading Example
33022N.A.
9901a55b 33023@end ignore
a2c02241
NR
33024
33025
33026@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33027@node GDB/MI File Commands
33028@section @sc{gdb/mi} File Commands
33029
33030This section describes the GDB/MI commands to specify executable file names
33031and to read in and obtain symbol table information.
33032
33033@subheading The @code{-file-exec-and-symbols} Command
33034@findex -file-exec-and-symbols
33035
33036@subsubheading Synopsis
922fbb7b
AC
33037
33038@smallexample
a2c02241 33039 -file-exec-and-symbols @var{file}
922fbb7b
AC
33040@end smallexample
33041
a2c02241
NR
33042Specify the executable file to be debugged. This file is the one from
33043which the symbol table is also read. If no file is specified, the
33044command clears the executable and symbol information. If breakpoints
33045are set when using this command with no arguments, @value{GDBN} will produce
33046error messages. Otherwise, no output is produced, except a completion
33047notification.
33048
922fbb7b
AC
33049@subsubheading @value{GDBN} Command
33050
a2c02241 33051The corresponding @value{GDBN} command is @samp{file}.
922fbb7b
AC
33052
33053@subsubheading Example
33054
33055@smallexample
594fe323 33056(gdb)
a2c02241
NR
33057-file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
33058^done
594fe323 33059(gdb)
922fbb7b
AC
33060@end smallexample
33061
922fbb7b 33062
a2c02241
NR
33063@subheading The @code{-file-exec-file} Command
33064@findex -file-exec-file
922fbb7b
AC
33065
33066@subsubheading Synopsis
33067
33068@smallexample
a2c02241 33069 -file-exec-file @var{file}
922fbb7b
AC
33070@end smallexample
33071
a2c02241
NR
33072Specify the executable file to be debugged. Unlike
33073@samp{-file-exec-and-symbols}, the symbol table is @emph{not} read
33074from this file. If used without argument, @value{GDBN} clears the information
33075about the executable file. No output is produced, except a completion
33076notification.
922fbb7b 33077
a2c02241
NR
33078@subsubheading @value{GDBN} Command
33079
33080The corresponding @value{GDBN} command is @samp{exec-file}.
922fbb7b
AC
33081
33082@subsubheading Example
a2c02241
NR
33083
33084@smallexample
594fe323 33085(gdb)
a2c02241
NR
33086-file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
33087^done
594fe323 33088(gdb)
a2c02241 33089@end smallexample
922fbb7b
AC
33090
33091
9901a55b 33092@ignore
a2c02241
NR
33093@subheading The @code{-file-list-exec-sections} Command
33094@findex -file-list-exec-sections
922fbb7b
AC
33095
33096@subsubheading Synopsis
33097
33098@smallexample
a2c02241 33099 -file-list-exec-sections
922fbb7b
AC
33100@end smallexample
33101
a2c02241
NR
33102List the sections of the current executable file.
33103
922fbb7b
AC
33104@subsubheading @value{GDBN} Command
33105
a2c02241
NR
33106The @value{GDBN} command @samp{info file} shows, among the rest, the same
33107information as this command. @code{gdbtk} has a corresponding command
33108@samp{gdb_load_info}.
922fbb7b
AC
33109
33110@subsubheading Example
33111N.A.
9901a55b 33112@end ignore
922fbb7b
AC
33113
33114
a2c02241
NR
33115@subheading The @code{-file-list-exec-source-file} Command
33116@findex -file-list-exec-source-file
922fbb7b
AC
33117
33118@subsubheading Synopsis
33119
33120@smallexample
a2c02241 33121 -file-list-exec-source-file
922fbb7b
AC
33122@end smallexample
33123
a2c02241 33124List the line number, the current source file, and the absolute path
44288b44
NR
33125to the current source file for the current executable. The macro
33126information field has a value of @samp{1} or @samp{0} depending on
33127whether or not the file includes preprocessor macro information.
922fbb7b
AC
33128
33129@subsubheading @value{GDBN} Command
33130
a2c02241 33131The @value{GDBN} equivalent is @samp{info source}
922fbb7b
AC
33132
33133@subsubheading Example
33134
922fbb7b 33135@smallexample
594fe323 33136(gdb)
a2c02241 33137123-file-list-exec-source-file
44288b44 33138123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1"
594fe323 33139(gdb)
922fbb7b
AC
33140@end smallexample
33141
33142
a2c02241
NR
33143@subheading The @code{-file-list-exec-source-files} Command
33144@findex -file-list-exec-source-files
922fbb7b
AC
33145
33146@subsubheading Synopsis
33147
33148@smallexample
a2c02241 33149 -file-list-exec-source-files
922fbb7b
AC
33150@end smallexample
33151
a2c02241
NR
33152List the source files for the current executable.
33153
f35a17b5
JK
33154It will always output both the filename and fullname (absolute file
33155name) of a source file.
922fbb7b
AC
33156
33157@subsubheading @value{GDBN} Command
33158
a2c02241
NR
33159The @value{GDBN} equivalent is @samp{info sources}.
33160@code{gdbtk} has an analogous command @samp{gdb_listfiles}.
922fbb7b
AC
33161
33162@subsubheading Example
922fbb7b 33163@smallexample
594fe323 33164(gdb)
a2c02241
NR
33165-file-list-exec-source-files
33166^done,files=[
33167@{file=foo.c,fullname=/home/foo.c@},
33168@{file=/home/bar.c,fullname=/home/bar.c@},
33169@{file=gdb_could_not_find_fullpath.c@}]
594fe323 33170(gdb)
922fbb7b
AC
33171@end smallexample
33172
a2c02241
NR
33173@subheading The @code{-file-list-shared-libraries} Command
33174@findex -file-list-shared-libraries
922fbb7b 33175
a2c02241 33176@subsubheading Synopsis
922fbb7b 33177
a2c02241 33178@smallexample
51457a05 33179 -file-list-shared-libraries [ @var{regexp} ]
a2c02241 33180@end smallexample
922fbb7b 33181
a2c02241 33182List the shared libraries in the program.
51457a05
MAL
33183With a regular expression @var{regexp}, only those libraries whose
33184names match @var{regexp} are listed.
922fbb7b 33185
a2c02241 33186@subsubheading @value{GDBN} Command
922fbb7b 33187
51457a05
MAL
33188The corresponding @value{GDBN} command is @samp{info shared}. The fields
33189have a similar meaning to the @code{=library-loaded} notification.
33190The @code{ranges} field specifies the multiple segments belonging to this
33191library. Each range has the following fields:
33192
33193@table @samp
33194@item from
33195The address defining the inclusive lower bound of the segment.
33196@item to
33197The address defining the exclusive upper bound of the segment.
33198@end table
922fbb7b 33199
a2c02241 33200@subsubheading Example
51457a05
MAL
33201@smallexample
33202(gdb)
33203-file-list-exec-source-files
33204^done,shared-libraries=[
33205@{id="/lib/libfoo.so",target-name="/lib/libfoo.so",host-name="/lib/libfoo.so",symbols-loaded="1",thread-group="i1",ranges=[@{from="0x72815989",to="0x728162c0"@}]@},
33206@{id="/lib/libbar.so",target-name="/lib/libbar.so",host-name="/lib/libbar.so",symbols-loaded="1",thread-group="i1",ranges=[@{from="0x76ee48c0",to="0x76ee9160"@}]@}]
33207(gdb)
33208@end smallexample
922fbb7b
AC
33209
33210
51457a05 33211@ignore
a2c02241
NR
33212@subheading The @code{-file-list-symbol-files} Command
33213@findex -file-list-symbol-files
922fbb7b 33214
a2c02241 33215@subsubheading Synopsis
922fbb7b 33216
a2c02241
NR
33217@smallexample
33218 -file-list-symbol-files
33219@end smallexample
922fbb7b 33220
a2c02241 33221List symbol files.
922fbb7b 33222
a2c02241 33223@subsubheading @value{GDBN} Command
922fbb7b 33224
a2c02241 33225The corresponding @value{GDBN} command is @samp{info file} (part of it).
922fbb7b 33226
a2c02241
NR
33227@subsubheading Example
33228N.A.
9901a55b 33229@end ignore
922fbb7b 33230
922fbb7b 33231
a2c02241
NR
33232@subheading The @code{-file-symbol-file} Command
33233@findex -file-symbol-file
922fbb7b 33234
a2c02241 33235@subsubheading Synopsis
922fbb7b 33236
a2c02241
NR
33237@smallexample
33238 -file-symbol-file @var{file}
33239@end smallexample
922fbb7b 33240
a2c02241
NR
33241Read symbol table info from the specified @var{file} argument. When
33242used without arguments, clears @value{GDBN}'s symbol table info. No output is
33243produced, except for a completion notification.
922fbb7b 33244
a2c02241 33245@subsubheading @value{GDBN} Command
922fbb7b 33246
a2c02241 33247The corresponding @value{GDBN} command is @samp{symbol-file}.
922fbb7b 33248
a2c02241 33249@subsubheading Example
922fbb7b 33250
a2c02241 33251@smallexample
594fe323 33252(gdb)
a2c02241
NR
33253-file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
33254^done
594fe323 33255(gdb)
a2c02241 33256@end smallexample
922fbb7b 33257
a2c02241 33258@ignore
a2c02241
NR
33259@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33260@node GDB/MI Memory Overlay Commands
33261@section @sc{gdb/mi} Memory Overlay Commands
922fbb7b 33262
a2c02241 33263The memory overlay commands are not implemented.
922fbb7b 33264
a2c02241 33265@c @subheading -overlay-auto
922fbb7b 33266
a2c02241 33267@c @subheading -overlay-list-mapping-state
922fbb7b 33268
a2c02241 33269@c @subheading -overlay-list-overlays
922fbb7b 33270
a2c02241 33271@c @subheading -overlay-map
922fbb7b 33272
a2c02241 33273@c @subheading -overlay-off
922fbb7b 33274
a2c02241 33275@c @subheading -overlay-on
922fbb7b 33276
a2c02241 33277@c @subheading -overlay-unmap
922fbb7b 33278
a2c02241
NR
33279@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33280@node GDB/MI Signal Handling Commands
33281@section @sc{gdb/mi} Signal Handling Commands
922fbb7b 33282
a2c02241 33283Signal handling commands are not implemented.
922fbb7b 33284
a2c02241 33285@c @subheading -signal-handle
922fbb7b 33286
a2c02241 33287@c @subheading -signal-list-handle-actions
922fbb7b 33288
a2c02241
NR
33289@c @subheading -signal-list-signal-types
33290@end ignore
922fbb7b 33291
922fbb7b 33292
a2c02241
NR
33293@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33294@node GDB/MI Target Manipulation
33295@section @sc{gdb/mi} Target Manipulation Commands
922fbb7b
AC
33296
33297
a2c02241
NR
33298@subheading The @code{-target-attach} Command
33299@findex -target-attach
922fbb7b
AC
33300
33301@subsubheading Synopsis
33302
33303@smallexample
c3b108f7 33304 -target-attach @var{pid} | @var{gid} | @var{file}
922fbb7b
AC
33305@end smallexample
33306
c3b108f7
VP
33307Attach to a process @var{pid} or a file @var{file} outside of
33308@value{GDBN}, or a thread group @var{gid}. If attaching to a thread
33309group, the id previously returned by
33310@samp{-list-thread-groups --available} must be used.
922fbb7b 33311
79a6e687 33312@subsubheading @value{GDBN} Command
922fbb7b 33313
a2c02241 33314The corresponding @value{GDBN} command is @samp{attach}.
922fbb7b 33315
a2c02241 33316@subsubheading Example
b56e7235
VP
33317@smallexample
33318(gdb)
33319-target-attach 34
33320=thread-created,id="1"
5ae4183a 33321*stopped,thread-id="1",frame=@{addr="0xb7f7e410",func="bar",args=[]@}
b56e7235
VP
33322^done
33323(gdb)
33324@end smallexample
a2c02241 33325
9901a55b 33326@ignore
a2c02241
NR
33327@subheading The @code{-target-compare-sections} Command
33328@findex -target-compare-sections
922fbb7b
AC
33329
33330@subsubheading Synopsis
33331
33332@smallexample
a2c02241 33333 -target-compare-sections [ @var{section} ]
922fbb7b
AC
33334@end smallexample
33335
a2c02241
NR
33336Compare data of section @var{section} on target to the exec file.
33337Without the argument, all sections are compared.
922fbb7b 33338
a2c02241 33339@subsubheading @value{GDBN} Command
922fbb7b 33340
a2c02241 33341The @value{GDBN} equivalent is @samp{compare-sections}.
922fbb7b 33342
a2c02241
NR
33343@subsubheading Example
33344N.A.
9901a55b 33345@end ignore
a2c02241
NR
33346
33347
33348@subheading The @code{-target-detach} Command
33349@findex -target-detach
922fbb7b
AC
33350
33351@subsubheading Synopsis
33352
33353@smallexample
c3b108f7 33354 -target-detach [ @var{pid} | @var{gid} ]
922fbb7b
AC
33355@end smallexample
33356
a2c02241 33357Detach from the remote target which normally resumes its execution.
c3b108f7
VP
33358If either @var{pid} or @var{gid} is specified, detaches from either
33359the specified process, or specified thread group. There's no output.
a2c02241 33360
79a6e687 33361@subsubheading @value{GDBN} Command
a2c02241
NR
33362
33363The corresponding @value{GDBN} command is @samp{detach}.
33364
33365@subsubheading Example
922fbb7b
AC
33366
33367@smallexample
594fe323 33368(gdb)
a2c02241
NR
33369-target-detach
33370^done
594fe323 33371(gdb)
922fbb7b
AC
33372@end smallexample
33373
33374
a2c02241
NR
33375@subheading The @code{-target-disconnect} Command
33376@findex -target-disconnect
922fbb7b
AC
33377
33378@subsubheading Synopsis
33379
123dc839 33380@smallexample
a2c02241 33381 -target-disconnect
123dc839 33382@end smallexample
922fbb7b 33383
a2c02241
NR
33384Disconnect from the remote target. There's no output and the target is
33385generally not resumed.
33386
79a6e687 33387@subsubheading @value{GDBN} Command
a2c02241
NR
33388
33389The corresponding @value{GDBN} command is @samp{disconnect}.
bc8ced35
NR
33390
33391@subsubheading Example
922fbb7b
AC
33392
33393@smallexample
594fe323 33394(gdb)
a2c02241
NR
33395-target-disconnect
33396^done
594fe323 33397(gdb)
922fbb7b
AC
33398@end smallexample
33399
33400
a2c02241
NR
33401@subheading The @code{-target-download} Command
33402@findex -target-download
922fbb7b
AC
33403
33404@subsubheading Synopsis
33405
33406@smallexample
a2c02241 33407 -target-download
922fbb7b
AC
33408@end smallexample
33409
a2c02241
NR
33410Loads the executable onto the remote target.
33411It prints out an update message every half second, which includes the fields:
33412
33413@table @samp
33414@item section
33415The name of the section.
33416@item section-sent
33417The size of what has been sent so far for that section.
33418@item section-size
33419The size of the section.
33420@item total-sent
33421The total size of what was sent so far (the current and the previous sections).
33422@item total-size
33423The size of the overall executable to download.
33424@end table
33425
33426@noindent
33427Each message is sent as status record (@pxref{GDB/MI Output Syntax, ,
33428@sc{gdb/mi} Output Syntax}).
33429
33430In addition, it prints the name and size of the sections, as they are
33431downloaded. These messages include the following fields:
33432
33433@table @samp
33434@item section
33435The name of the section.
33436@item section-size
33437The size of the section.
33438@item total-size
33439The size of the overall executable to download.
33440@end table
33441
33442@noindent
33443At the end, a summary is printed.
33444
33445@subsubheading @value{GDBN} Command
33446
33447The corresponding @value{GDBN} command is @samp{load}.
33448
33449@subsubheading Example
33450
33451Note: each status message appears on a single line. Here the messages
33452have been broken down so that they can fit onto a page.
922fbb7b
AC
33453
33454@smallexample
594fe323 33455(gdb)
a2c02241
NR
33456-target-download
33457+download,@{section=".text",section-size="6668",total-size="9880"@}
33458+download,@{section=".text",section-sent="512",section-size="6668",
33459total-sent="512",total-size="9880"@}
33460+download,@{section=".text",section-sent="1024",section-size="6668",
33461total-sent="1024",total-size="9880"@}
33462+download,@{section=".text",section-sent="1536",section-size="6668",
33463total-sent="1536",total-size="9880"@}
33464+download,@{section=".text",section-sent="2048",section-size="6668",
33465total-sent="2048",total-size="9880"@}
33466+download,@{section=".text",section-sent="2560",section-size="6668",
33467total-sent="2560",total-size="9880"@}
33468+download,@{section=".text",section-sent="3072",section-size="6668",
33469total-sent="3072",total-size="9880"@}
33470+download,@{section=".text",section-sent="3584",section-size="6668",
33471total-sent="3584",total-size="9880"@}
33472+download,@{section=".text",section-sent="4096",section-size="6668",
33473total-sent="4096",total-size="9880"@}
33474+download,@{section=".text",section-sent="4608",section-size="6668",
33475total-sent="4608",total-size="9880"@}
33476+download,@{section=".text",section-sent="5120",section-size="6668",
33477total-sent="5120",total-size="9880"@}
33478+download,@{section=".text",section-sent="5632",section-size="6668",
33479total-sent="5632",total-size="9880"@}
33480+download,@{section=".text",section-sent="6144",section-size="6668",
33481total-sent="6144",total-size="9880"@}
33482+download,@{section=".text",section-sent="6656",section-size="6668",
33483total-sent="6656",total-size="9880"@}
33484+download,@{section=".init",section-size="28",total-size="9880"@}
33485+download,@{section=".fini",section-size="28",total-size="9880"@}
33486+download,@{section=".data",section-size="3156",total-size="9880"@}
33487+download,@{section=".data",section-sent="512",section-size="3156",
33488total-sent="7236",total-size="9880"@}
33489+download,@{section=".data",section-sent="1024",section-size="3156",
33490total-sent="7748",total-size="9880"@}
33491+download,@{section=".data",section-sent="1536",section-size="3156",
33492total-sent="8260",total-size="9880"@}
33493+download,@{section=".data",section-sent="2048",section-size="3156",
33494total-sent="8772",total-size="9880"@}
33495+download,@{section=".data",section-sent="2560",section-size="3156",
33496total-sent="9284",total-size="9880"@}
33497+download,@{section=".data",section-sent="3072",section-size="3156",
33498total-sent="9796",total-size="9880"@}
33499^done,address="0x10004",load-size="9880",transfer-rate="6586",
33500write-rate="429"
594fe323 33501(gdb)
922fbb7b
AC
33502@end smallexample
33503
33504
9901a55b 33505@ignore
a2c02241
NR
33506@subheading The @code{-target-exec-status} Command
33507@findex -target-exec-status
922fbb7b
AC
33508
33509@subsubheading Synopsis
33510
33511@smallexample
a2c02241 33512 -target-exec-status
922fbb7b
AC
33513@end smallexample
33514
a2c02241
NR
33515Provide information on the state of the target (whether it is running or
33516not, for instance).
922fbb7b 33517
a2c02241 33518@subsubheading @value{GDBN} Command
922fbb7b 33519
a2c02241
NR
33520There's no equivalent @value{GDBN} command.
33521
33522@subsubheading Example
33523N.A.
922fbb7b 33524
a2c02241
NR
33525
33526@subheading The @code{-target-list-available-targets} Command
33527@findex -target-list-available-targets
922fbb7b
AC
33528
33529@subsubheading Synopsis
33530
33531@smallexample
a2c02241 33532 -target-list-available-targets
922fbb7b
AC
33533@end smallexample
33534
a2c02241 33535List the possible targets to connect to.
922fbb7b 33536
a2c02241 33537@subsubheading @value{GDBN} Command
922fbb7b 33538
a2c02241 33539The corresponding @value{GDBN} command is @samp{help target}.
922fbb7b 33540
a2c02241
NR
33541@subsubheading Example
33542N.A.
33543
33544
33545@subheading The @code{-target-list-current-targets} Command
33546@findex -target-list-current-targets
922fbb7b
AC
33547
33548@subsubheading Synopsis
33549
33550@smallexample
a2c02241 33551 -target-list-current-targets
922fbb7b
AC
33552@end smallexample
33553
a2c02241 33554Describe the current target.
922fbb7b 33555
a2c02241 33556@subsubheading @value{GDBN} Command
922fbb7b 33557
a2c02241
NR
33558The corresponding information is printed by @samp{info file} (among
33559other things).
922fbb7b 33560
a2c02241
NR
33561@subsubheading Example
33562N.A.
33563
33564
33565@subheading The @code{-target-list-parameters} Command
33566@findex -target-list-parameters
922fbb7b
AC
33567
33568@subsubheading Synopsis
33569
33570@smallexample
a2c02241 33571 -target-list-parameters
922fbb7b
AC
33572@end smallexample
33573
a2c02241 33574@c ????
9901a55b 33575@end ignore
a2c02241
NR
33576
33577@subsubheading @value{GDBN} Command
33578
33579No equivalent.
922fbb7b
AC
33580
33581@subsubheading Example
a2c02241
NR
33582N.A.
33583
78cbbba8
LM
33584@subheading The @code{-target-flash-erase} Command
33585@findex -target-flash-erase
33586
33587@subsubheading Synopsis
33588
33589@smallexample
33590 -target-flash-erase
33591@end smallexample
33592
33593Erases all known flash memory regions on the target.
33594
33595The corresponding @value{GDBN} command is @samp{flash-erase}.
33596
33597The output is a list of flash regions that have been erased, with starting
33598addresses and memory region sizes.
33599
33600@smallexample
33601(gdb)
33602-target-flash-erase
33603^done,erased-regions=@{address="0x0",size="0x40000"@}
33604(gdb)
33605@end smallexample
a2c02241
NR
33606
33607@subheading The @code{-target-select} Command
33608@findex -target-select
33609
33610@subsubheading Synopsis
922fbb7b
AC
33611
33612@smallexample
a2c02241 33613 -target-select @var{type} @var{parameters @dots{}}
922fbb7b
AC
33614@end smallexample
33615
a2c02241 33616Connect @value{GDBN} to the remote target. This command takes two args:
922fbb7b 33617
a2c02241
NR
33618@table @samp
33619@item @var{type}
75c99385 33620The type of target, for instance @samp{remote}, etc.
a2c02241
NR
33621@item @var{parameters}
33622Device names, host names and the like. @xref{Target Commands, ,
79a6e687 33623Commands for Managing Targets}, for more details.
a2c02241
NR
33624@end table
33625
33626The output is a connection notification, followed by the address at
33627which the target program is, in the following form:
922fbb7b
AC
33628
33629@smallexample
a2c02241
NR
33630^connected,addr="@var{address}",func="@var{function name}",
33631 args=[@var{arg list}]
922fbb7b
AC
33632@end smallexample
33633
a2c02241
NR
33634@subsubheading @value{GDBN} Command
33635
33636The corresponding @value{GDBN} command is @samp{target}.
265eeb58
NR
33637
33638@subsubheading Example
922fbb7b 33639
265eeb58 33640@smallexample
594fe323 33641(gdb)
75c99385 33642-target-select remote /dev/ttya
a2c02241 33643^connected,addr="0xfe00a300",func="??",args=[]
594fe323 33644(gdb)
265eeb58 33645@end smallexample
ef21caaf 33646
a6b151f1
DJ
33647@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33648@node GDB/MI File Transfer Commands
33649@section @sc{gdb/mi} File Transfer Commands
33650
33651
33652@subheading The @code{-target-file-put} Command
33653@findex -target-file-put
33654
33655@subsubheading Synopsis
33656
33657@smallexample
33658 -target-file-put @var{hostfile} @var{targetfile}
33659@end smallexample
33660
33661Copy file @var{hostfile} from the host system (the machine running
33662@value{GDBN}) to @var{targetfile} on the target system.
33663
33664@subsubheading @value{GDBN} Command
33665
33666The corresponding @value{GDBN} command is @samp{remote put}.
33667
33668@subsubheading Example
33669
33670@smallexample
33671(gdb)
33672-target-file-put localfile remotefile
33673^done
33674(gdb)
33675@end smallexample
33676
33677
1763a388 33678@subheading The @code{-target-file-get} Command
a6b151f1
DJ
33679@findex -target-file-get
33680
33681@subsubheading Synopsis
33682
33683@smallexample
33684 -target-file-get @var{targetfile} @var{hostfile}
33685@end smallexample
33686
33687Copy file @var{targetfile} from the target system to @var{hostfile}
33688on the host system.
33689
33690@subsubheading @value{GDBN} Command
33691
33692The corresponding @value{GDBN} command is @samp{remote get}.
33693
33694@subsubheading Example
33695
33696@smallexample
33697(gdb)
33698-target-file-get remotefile localfile
33699^done
33700(gdb)
33701@end smallexample
33702
33703
33704@subheading The @code{-target-file-delete} Command
33705@findex -target-file-delete
33706
33707@subsubheading Synopsis
33708
33709@smallexample
33710 -target-file-delete @var{targetfile}
33711@end smallexample
33712
33713Delete @var{targetfile} from the target system.
33714
33715@subsubheading @value{GDBN} Command
33716
33717The corresponding @value{GDBN} command is @samp{remote delete}.
33718
33719@subsubheading Example
33720
33721@smallexample
33722(gdb)
33723-target-file-delete remotefile
33724^done
33725(gdb)
33726@end smallexample
33727
33728
58d06528
JB
33729@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33730@node GDB/MI Ada Exceptions Commands
33731@section Ada Exceptions @sc{gdb/mi} Commands
33732
33733@subheading The @code{-info-ada-exceptions} Command
33734@findex -info-ada-exceptions
33735
33736@subsubheading Synopsis
33737
33738@smallexample
33739 -info-ada-exceptions [ @var{regexp}]
33740@end smallexample
33741
33742List all Ada exceptions defined within the program being debugged.
33743With a regular expression @var{regexp}, only those exceptions whose
33744names match @var{regexp} are listed.
33745
33746@subsubheading @value{GDBN} Command
33747
33748The corresponding @value{GDBN} command is @samp{info exceptions}.
33749
33750@subsubheading Result
33751
33752The result is a table of Ada exceptions. The following columns are
33753defined for each exception:
33754
33755@table @samp
33756@item name
33757The name of the exception.
33758
33759@item address
33760The address of the exception.
33761
33762@end table
33763
33764@subsubheading Example
33765
33766@smallexample
33767-info-ada-exceptions aint
33768^done,ada-exceptions=@{nr_rows="2",nr_cols="2",
33769hdr=[@{width="1",alignment="-1",col_name="name",colhdr="Name"@},
33770@{width="1",alignment="-1",col_name="address",colhdr="Address"@}],
33771body=[@{name="constraint_error",address="0x0000000000613da0"@},
33772@{name="const.aint_global_e",address="0x0000000000613b00"@}]@}
33773@end smallexample
33774
33775@subheading Catching Ada Exceptions
33776
33777The commands describing how to ask @value{GDBN} to stop when a program
33778raises an exception are described at @ref{Ada Exception GDB/MI
33779Catchpoint Commands}.
33780
33781
ef21caaf 33782@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
d192b373
JB
33783@node GDB/MI Support Commands
33784@section @sc{gdb/mi} Support Commands
ef21caaf 33785
d192b373
JB
33786Since new commands and features get regularly added to @sc{gdb/mi},
33787some commands are available to help front-ends query the debugger
33788about support for these capabilities. Similarly, it is also possible
33789to query @value{GDBN} about target support of certain features.
ef21caaf 33790
6b7cbff1
JB
33791@subheading The @code{-info-gdb-mi-command} Command
33792@cindex @code{-info-gdb-mi-command}
33793@findex -info-gdb-mi-command
33794
33795@subsubheading Synopsis
33796
33797@smallexample
33798 -info-gdb-mi-command @var{cmd_name}
33799@end smallexample
33800
33801Query support for the @sc{gdb/mi} command named @var{cmd_name}.
33802
33803Note that the dash (@code{-}) starting all @sc{gdb/mi} commands
33804is technically not part of the command name (@pxref{GDB/MI Input
33805Syntax}), and thus should be omitted in @var{cmd_name}. However,
33806for ease of use, this command also accepts the form with the leading
33807dash.
33808
33809@subsubheading @value{GDBN} Command
33810
33811There is no corresponding @value{GDBN} command.
33812
33813@subsubheading Result
33814
33815The result is a tuple. There is currently only one field:
33816
33817@table @samp
33818@item exists
33819This field is equal to @code{"true"} if the @sc{gdb/mi} command exists,
33820@code{"false"} otherwise.
33821
33822@end table
33823
33824@subsubheading Example
33825
33826Here is an example where the @sc{gdb/mi} command does not exist:
33827
33828@smallexample
33829-info-gdb-mi-command unsupported-command
33830^done,command=@{exists="false"@}
33831@end smallexample
33832
33833@noindent
33834And here is an example where the @sc{gdb/mi} command is known
33835to the debugger:
33836
33837@smallexample
33838-info-gdb-mi-command symbol-list-lines
33839^done,command=@{exists="true"@}
33840@end smallexample
33841
084344da
VP
33842@subheading The @code{-list-features} Command
33843@findex -list-features
9b26f0fb 33844@cindex supported @sc{gdb/mi} features, list
084344da
VP
33845
33846Returns a list of particular features of the MI protocol that
33847this version of gdb implements. A feature can be a command,
33848or a new field in an output of some command, or even an
33849important bugfix. While a frontend can sometimes detect presence
33850of a feature at runtime, it is easier to perform detection at debugger
d192b373 33851startup.
084344da
VP
33852
33853The command returns a list of strings, with each string naming an
33854available feature. Each returned string is just a name, it does not
d192b373 33855have any internal structure. The list of possible feature names
084344da
VP
33856is given below.
33857
33858Example output:
33859
33860@smallexample
33861(gdb) -list-features
33862^done,result=["feature1","feature2"]
33863@end smallexample
33864
33865The current list of features is:
33866
edef6000 33867@ftable @samp
30e026bb 33868@item frozen-varobjs
a05336a1
JB
33869Indicates support for the @code{-var-set-frozen} command, as well
33870as possible presense of the @code{frozen} field in the output
30e026bb
VP
33871of @code{-varobj-create}.
33872@item pending-breakpoints
a05336a1
JB
33873Indicates support for the @option{-f} option to the @code{-break-insert}
33874command.
b6313243 33875@item python
a05336a1 33876Indicates Python scripting support, Python-based
b6313243
TT
33877pretty-printing commands, and possible presence of the
33878@samp{display_hint} field in the output of @code{-var-list-children}
30e026bb 33879@item thread-info
a05336a1 33880Indicates support for the @code{-thread-info} command.
8dedea02 33881@item data-read-memory-bytes
a05336a1 33882Indicates support for the @code{-data-read-memory-bytes} and the
8dedea02 33883@code{-data-write-memory-bytes} commands.
39c4d40a
TT
33884@item breakpoint-notifications
33885Indicates that changes to breakpoints and breakpoints created via the
33886CLI will be announced via async records.
5d77fe44 33887@item ada-task-info
6adcee18 33888Indicates support for the @code{-ada-task-info} command.
422ad5c2
JB
33889@item language-option
33890Indicates that all @sc{gdb/mi} commands accept the @option{--language}
33891option (@pxref{Context management}).
6b7cbff1
JB
33892@item info-gdb-mi-command
33893Indicates support for the @code{-info-gdb-mi-command} command.
2ea126fa
JB
33894@item undefined-command-error-code
33895Indicates support for the "undefined-command" error code in error result
33896records, produced when trying to execute an undefined @sc{gdb/mi} command
33897(@pxref{GDB/MI Result Records}).
72bfa06c
JB
33898@item exec-run-start-option
33899Indicates that the @code{-exec-run} command supports the @option{--start}
33900option (@pxref{GDB/MI Program Execution}).
26fb3983
JV
33901@item data-disassemble-a-option
33902Indicates that the @code{-data-disassemble} command supports the @option{-a}
33903option (@pxref{GDB/MI Data Manipulation}).
edef6000 33904@end ftable
084344da 33905
c6ebd6cf
VP
33906@subheading The @code{-list-target-features} Command
33907@findex -list-target-features
33908
33909Returns a list of particular features that are supported by the
33910target. Those features affect the permitted MI commands, but
33911unlike the features reported by the @code{-list-features} command, the
33912features depend on which target GDB is using at the moment. Whenever
33913a target can change, due to commands such as @code{-target-select},
33914@code{-target-attach} or @code{-exec-run}, the list of target features
33915may change, and the frontend should obtain it again.
33916Example output:
33917
33918@smallexample
b3d3b4bd 33919(gdb) -list-target-features
c6ebd6cf
VP
33920^done,result=["async"]
33921@end smallexample
33922
33923The current list of features is:
33924
33925@table @samp
33926@item async
33927Indicates that the target is capable of asynchronous command
33928execution, which means that @value{GDBN} will accept further commands
33929while the target is running.
33930
f75d858b
MK
33931@item reverse
33932Indicates that the target is capable of reverse execution.
33933@xref{Reverse Execution}, for more information.
33934
c6ebd6cf
VP
33935@end table
33936
d192b373
JB
33937@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33938@node GDB/MI Miscellaneous Commands
33939@section Miscellaneous @sc{gdb/mi} Commands
33940
33941@c @subheading -gdb-complete
33942
33943@subheading The @code{-gdb-exit} Command
33944@findex -gdb-exit
33945
33946@subsubheading Synopsis
33947
33948@smallexample
33949 -gdb-exit
33950@end smallexample
33951
33952Exit @value{GDBN} immediately.
33953
33954@subsubheading @value{GDBN} Command
33955
33956Approximately corresponds to @samp{quit}.
33957
33958@subsubheading Example
33959
33960@smallexample
33961(gdb)
33962-gdb-exit
33963^exit
33964@end smallexample
33965
33966
33967@ignore
33968@subheading The @code{-exec-abort} Command
33969@findex -exec-abort
33970
33971@subsubheading Synopsis
33972
33973@smallexample
33974 -exec-abort
33975@end smallexample
33976
33977Kill the inferior running program.
33978
33979@subsubheading @value{GDBN} Command
33980
33981The corresponding @value{GDBN} command is @samp{kill}.
33982
33983@subsubheading Example
33984N.A.
33985@end ignore
33986
33987
33988@subheading The @code{-gdb-set} Command
33989@findex -gdb-set
33990
33991@subsubheading Synopsis
33992
33993@smallexample
33994 -gdb-set
33995@end smallexample
33996
33997Set an internal @value{GDBN} variable.
33998@c IS THIS A DOLLAR VARIABLE? OR SOMETHING LIKE ANNOTATE ?????
33999
34000@subsubheading @value{GDBN} Command
34001
34002The corresponding @value{GDBN} command is @samp{set}.
34003
34004@subsubheading Example
34005
34006@smallexample
34007(gdb)
34008-gdb-set $foo=3
34009^done
34010(gdb)
34011@end smallexample
34012
34013
34014@subheading The @code{-gdb-show} Command
34015@findex -gdb-show
34016
34017@subsubheading Synopsis
34018
34019@smallexample
34020 -gdb-show
34021@end smallexample
34022
34023Show the current value of a @value{GDBN} variable.
34024
34025@subsubheading @value{GDBN} Command
34026
34027The corresponding @value{GDBN} command is @samp{show}.
34028
34029@subsubheading Example
34030
34031@smallexample
34032(gdb)
34033-gdb-show annotate
34034^done,value="0"
34035(gdb)
34036@end smallexample
34037
34038@c @subheading -gdb-source
34039
34040
34041@subheading The @code{-gdb-version} Command
34042@findex -gdb-version
34043
34044@subsubheading Synopsis
34045
34046@smallexample
34047 -gdb-version
34048@end smallexample
34049
34050Show version information for @value{GDBN}. Used mostly in testing.
34051
34052@subsubheading @value{GDBN} Command
34053
34054The @value{GDBN} equivalent is @samp{show version}. @value{GDBN} by
34055default shows this information when you start an interactive session.
34056
34057@subsubheading Example
34058
34059@c This example modifies the actual output from GDB to avoid overfull
34060@c box in TeX.
34061@smallexample
34062(gdb)
34063-gdb-version
34064~GNU gdb 5.2.1
34065~Copyright 2000 Free Software Foundation, Inc.
34066~GDB is free software, covered by the GNU General Public License, and
34067~you are welcome to change it and/or distribute copies of it under
34068~ certain conditions.
34069~Type "show copying" to see the conditions.
34070~There is absolutely no warranty for GDB. Type "show warranty" for
34071~ details.
34072~This GDB was configured as
34073 "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
34074^done
34075(gdb)
34076@end smallexample
34077
c3b108f7
VP
34078@subheading The @code{-list-thread-groups} Command
34079@findex -list-thread-groups
34080
34081@subheading Synopsis
34082
34083@smallexample
dc146f7c 34084-list-thread-groups [ --available ] [ --recurse 1 ] [ @var{group} ... ]
c3b108f7
VP
34085@end smallexample
34086
dc146f7c
VP
34087Lists thread groups (@pxref{Thread groups}). When a single thread
34088group is passed as the argument, lists the children of that group.
34089When several thread group are passed, lists information about those
34090thread groups. Without any parameters, lists information about all
34091top-level thread groups.
34092
34093Normally, thread groups that are being debugged are reported.
34094With the @samp{--available} option, @value{GDBN} reports thread groups
34095available on the target.
34096
34097The output of this command may have either a @samp{threads} result or
34098a @samp{groups} result. The @samp{thread} result has a list of tuples
34099as value, with each tuple describing a thread (@pxref{GDB/MI Thread
34100Information}). The @samp{groups} result has a list of tuples as value,
34101each tuple describing a thread group. If top-level groups are
34102requested (that is, no parameter is passed), or when several groups
34103are passed, the output always has a @samp{groups} result. The format
34104of the @samp{group} result is described below.
34105
34106To reduce the number of roundtrips it's possible to list thread groups
34107together with their children, by passing the @samp{--recurse} option
34108and the recursion depth. Presently, only recursion depth of 1 is
34109permitted. If this option is present, then every reported thread group
34110will also include its children, either as @samp{group} or
34111@samp{threads} field.
34112
34113In general, any combination of option and parameters is permitted, with
34114the following caveats:
34115
34116@itemize @bullet
34117@item
34118When a single thread group is passed, the output will typically
34119be the @samp{threads} result. Because threads may not contain
34120anything, the @samp{recurse} option will be ignored.
34121
34122@item
34123When the @samp{--available} option is passed, limited information may
34124be available. In particular, the list of threads of a process might
34125be inaccessible. Further, specifying specific thread groups might
34126not give any performance advantage over listing all thread groups.
34127The frontend should assume that @samp{-list-thread-groups --available}
34128is always an expensive operation and cache the results.
34129
34130@end itemize
34131
34132The @samp{groups} result is a list of tuples, where each tuple may
34133have the following fields:
34134
34135@table @code
34136@item id
34137Identifier of the thread group. This field is always present.
a79b8f6e
VP
34138The identifier is an opaque string; frontends should not try to
34139convert it to an integer, even though it might look like one.
dc146f7c
VP
34140
34141@item type
34142The type of the thread group. At present, only @samp{process} is a
34143valid type.
34144
34145@item pid
34146The target-specific process identifier. This field is only present
a79b8f6e 34147for thread groups of type @samp{process} and only if the process exists.
c3b108f7 34148
2ddf4301
SM
34149@item exit-code
34150The exit code of this group's last exited thread, formatted in octal.
34151This field is only present for thread groups of type @samp{process} and
34152only if the process is not running.
34153
dc146f7c
VP
34154@item num_children
34155The number of children this thread group has. This field may be
34156absent for an available thread group.
34157
34158@item threads
34159This field has a list of tuples as value, each tuple describing a
34160thread. It may be present if the @samp{--recurse} option is
34161specified, and it's actually possible to obtain the threads.
34162
34163@item cores
34164This field is a list of integers, each identifying a core that one
34165thread of the group is running on. This field may be absent if
34166such information is not available.
34167
a79b8f6e
VP
34168@item executable
34169The name of the executable file that corresponds to this thread group.
34170The field is only present for thread groups of type @samp{process},
34171and only if there is a corresponding executable file.
34172
dc146f7c 34173@end table
c3b108f7
VP
34174
34175@subheading Example
34176
34177@smallexample
34178@value{GDBP}
34179-list-thread-groups
34180^done,groups=[@{id="17",type="process",pid="yyy",num_children="2"@}]
34181-list-thread-groups 17
34182^done,threads=[@{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
34183 frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]@},state="running"@},
34184@{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
34185 frame=@{level="0",addr="0x0804891f",func="foo",args=[@{name="i",value="10"@}],
6d52907e 34186 file="/tmp/a.c",fullname="/tmp/a.c",line="158",arch="i386:x86_64"@},state="running"@}]]
dc146f7c
VP
34187-list-thread-groups --available
34188^done,groups=[@{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]@}]
34189-list-thread-groups --available --recurse 1
34190 ^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
34191 threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
34192 @{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},..]
34193-list-thread-groups --available --recurse 1 17 18
34194^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
34195 threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
34196 @{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},...]
c3b108f7 34197@end smallexample
c6ebd6cf 34198
f3e0e960
SS
34199@subheading The @code{-info-os} Command
34200@findex -info-os
34201
34202@subsubheading Synopsis
34203
34204@smallexample
34205-info-os [ @var{type} ]
34206@end smallexample
34207
34208If no argument is supplied, the command returns a table of available
34209operating-system-specific information types. If one of these types is
34210supplied as an argument @var{type}, then the command returns a table
34211of data of that type.
34212
34213The types of information available depend on the target operating
34214system.
34215
34216@subsubheading @value{GDBN} Command
34217
34218The corresponding @value{GDBN} command is @samp{info os}.
34219
34220@subsubheading Example
34221
34222When run on a @sc{gnu}/Linux system, the output will look something
34223like this:
34224
34225@smallexample
34226@value{GDBP}
34227-info-os
d33279b3 34228^done,OSDataTable=@{nr_rows="10",nr_cols="3",
f3e0e960 34229hdr=[@{width="10",alignment="-1",col_name="col0",colhdr="Type"@},
71caed83
SS
34230 @{width="10",alignment="-1",col_name="col1",colhdr="Description"@},
34231 @{width="10",alignment="-1",col_name="col2",colhdr="Title"@}],
d33279b3
AT
34232body=[item=@{col0="cpus",col1="Listing of all cpus/cores on the system",
34233 col2="CPUs"@},
34234 item=@{col0="files",col1="Listing of all file descriptors",
34235 col2="File descriptors"@},
34236 item=@{col0="modules",col1="Listing of all loaded kernel modules",
34237 col2="Kernel modules"@},
34238 item=@{col0="msg",col1="Listing of all message queues",
34239 col2="Message queues"@},
34240 item=@{col0="processes",col1="Listing of all processes",
71caed83
SS
34241 col2="Processes"@},
34242 item=@{col0="procgroups",col1="Listing of all process groups",
34243 col2="Process groups"@},
71caed83
SS
34244 item=@{col0="semaphores",col1="Listing of all semaphores",
34245 col2="Semaphores"@},
d33279b3
AT
34246 item=@{col0="shm",col1="Listing of all shared-memory regions",
34247 col2="Shared-memory regions"@},
34248 item=@{col0="sockets",col1="Listing of all internet-domain sockets",
34249 col2="Sockets"@},
34250 item=@{col0="threads",col1="Listing of all threads",
34251 col2="Threads"@}]
f3e0e960
SS
34252@value{GDBP}
34253-info-os processes
34254^done,OSDataTable=@{nr_rows="190",nr_cols="4",
34255hdr=[@{width="10",alignment="-1",col_name="col0",colhdr="pid"@},
34256 @{width="10",alignment="-1",col_name="col1",colhdr="user"@},
34257 @{width="10",alignment="-1",col_name="col2",colhdr="command"@},
34258 @{width="10",alignment="-1",col_name="col3",colhdr="cores"@}],
34259body=[item=@{col0="1",col1="root",col2="/sbin/init",col3="0"@},
34260 item=@{col0="2",col1="root",col2="[kthreadd]",col3="1"@},
34261 item=@{col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"@},
34262 ...
34263 item=@{col0="26446",col1="stan",col2="bash",col3="0"@},
34264 item=@{col0="28152",col1="stan",col2="bash",col3="1"@}]@}
34265(gdb)
34266@end smallexample
a79b8f6e 34267
71caed83
SS
34268(Note that the MI output here includes a @code{"Title"} column that
34269does not appear in command-line @code{info os}; this column is useful
34270for MI clients that want to enumerate the types of data, such as in a
34271popup menu, but is needless clutter on the command line, and
34272@code{info os} omits it.)
34273
a79b8f6e
VP
34274@subheading The @code{-add-inferior} Command
34275@findex -add-inferior
34276
34277@subheading Synopsis
34278
34279@smallexample
34280-add-inferior
34281@end smallexample
34282
34283Creates a new inferior (@pxref{Inferiors and Programs}). The created
34284inferior is not associated with any executable. Such association may
34285be established with the @samp{-file-exec-and-symbols} command
34286(@pxref{GDB/MI File Commands}). The command response has a single
b7742092 34287field, @samp{inferior}, whose value is the identifier of the
a79b8f6e
VP
34288thread group corresponding to the new inferior.
34289
34290@subheading Example
34291
34292@smallexample
34293@value{GDBP}
34294-add-inferior
b7742092 34295^done,inferior="i3"
a79b8f6e
VP
34296@end smallexample
34297
ef21caaf
NR
34298@subheading The @code{-interpreter-exec} Command
34299@findex -interpreter-exec
34300
34301@subheading Synopsis
34302
34303@smallexample
34304-interpreter-exec @var{interpreter} @var{command}
34305@end smallexample
a2c02241 34306@anchor{-interpreter-exec}
ef21caaf
NR
34307
34308Execute the specified @var{command} in the given @var{interpreter}.
34309
34310@subheading @value{GDBN} Command
34311
34312The corresponding @value{GDBN} command is @samp{interpreter-exec}.
34313
34314@subheading Example
34315
34316@smallexample
594fe323 34317(gdb)
ef21caaf
NR
34318-interpreter-exec console "break main"
34319&"During symbol reading, couldn't parse type; debugger out of date?.\n"
34320&"During symbol reading, bad structure-type format.\n"
34321~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
34322^done
594fe323 34323(gdb)
ef21caaf
NR
34324@end smallexample
34325
34326@subheading The @code{-inferior-tty-set} Command
34327@findex -inferior-tty-set
34328
34329@subheading Synopsis
34330
34331@smallexample
34332-inferior-tty-set /dev/pts/1
34333@end smallexample
34334
34335Set terminal for future runs of the program being debugged.
34336
34337@subheading @value{GDBN} Command
34338
34339The corresponding @value{GDBN} command is @samp{set inferior-tty} /dev/pts/1.
34340
34341@subheading Example
34342
34343@smallexample
594fe323 34344(gdb)
ef21caaf
NR
34345-inferior-tty-set /dev/pts/1
34346^done
594fe323 34347(gdb)
ef21caaf
NR
34348@end smallexample
34349
34350@subheading The @code{-inferior-tty-show} Command
34351@findex -inferior-tty-show
34352
34353@subheading Synopsis
34354
34355@smallexample
34356-inferior-tty-show
34357@end smallexample
34358
34359Show terminal for future runs of program being debugged.
34360
34361@subheading @value{GDBN} Command
34362
34363The corresponding @value{GDBN} command is @samp{show inferior-tty}.
34364
34365@subheading Example
34366
34367@smallexample
594fe323 34368(gdb)
ef21caaf
NR
34369-inferior-tty-set /dev/pts/1
34370^done
594fe323 34371(gdb)
ef21caaf
NR
34372-inferior-tty-show
34373^done,inferior_tty_terminal="/dev/pts/1"
594fe323 34374(gdb)
ef21caaf 34375@end smallexample
922fbb7b 34376
a4eefcd8
NR
34377@subheading The @code{-enable-timings} Command
34378@findex -enable-timings
34379
34380@subheading Synopsis
34381
34382@smallexample
34383-enable-timings [yes | no]
34384@end smallexample
34385
34386Toggle the printing of the wallclock, user and system times for an MI
34387command as a field in its output. This command is to help frontend
34388developers optimize the performance of their code. No argument is
34389equivalent to @samp{yes}.
34390
34391@subheading @value{GDBN} Command
34392
34393No equivalent.
34394
34395@subheading Example
34396
34397@smallexample
34398(gdb)
34399-enable-timings
34400^done
34401(gdb)
34402-break-insert main
34403^done,bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
34404addr="0x080484ed",func="main",file="myprog.c",
998580f1
MK
34405fullname="/home/nickrob/myprog.c",line="73",thread-groups=["i1"],
34406times="0"@},
a4eefcd8
NR
34407time=@{wallclock="0.05185",user="0.00800",system="0.00000"@}
34408(gdb)
34409-enable-timings no
34410^done
34411(gdb)
34412-exec-run
34413^running
34414(gdb)
a47ec5fe 34415*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
a4eefcd8
NR
34416frame=@{addr="0x080484ed",func="main",args=[@{name="argc",value="1"@},
34417@{name="argv",value="0xbfb60364"@}],file="myprog.c",
6d52907e 34418fullname="/home/nickrob/myprog.c",line="73",arch="i386:x86_64"@}
a4eefcd8
NR
34419(gdb)
34420@end smallexample
34421
922fbb7b
AC
34422@node Annotations
34423@chapter @value{GDBN} Annotations
34424
086432e2
AC
34425This chapter describes annotations in @value{GDBN}. Annotations were
34426designed to interface @value{GDBN} to graphical user interfaces or other
34427similar programs which want to interact with @value{GDBN} at a
922fbb7b
AC
34428relatively high level.
34429
d3e8051b 34430The annotation mechanism has largely been superseded by @sc{gdb/mi}
086432e2
AC
34431(@pxref{GDB/MI}).
34432
922fbb7b
AC
34433@ignore
34434This is Edition @value{EDITION}, @value{DATE}.
34435@end ignore
34436
34437@menu
34438* Annotations Overview:: What annotations are; the general syntax.
9e6c4bd5 34439* Server Prefix:: Issuing a command without affecting user state.
922fbb7b
AC
34440* Prompting:: Annotations marking @value{GDBN}'s need for input.
34441* Errors:: Annotations for error messages.
922fbb7b
AC
34442* Invalidation:: Some annotations describe things now invalid.
34443* Annotations for Running::
34444 Whether the program is running, how it stopped, etc.
34445* Source Annotations:: Annotations describing source code.
922fbb7b
AC
34446@end menu
34447
34448@node Annotations Overview
34449@section What is an Annotation?
34450@cindex annotations
34451
922fbb7b
AC
34452Annotations start with a newline character, two @samp{control-z}
34453characters, and the name of the annotation. If there is no additional
34454information associated with this annotation, the name of the annotation
34455is followed immediately by a newline. If there is additional
34456information, the name of the annotation is followed by a space, the
34457additional information, and a newline. The additional information
34458cannot contain newline characters.
34459
34460Any output not beginning with a newline and two @samp{control-z}
34461characters denotes literal output from @value{GDBN}. Currently there is
34462no need for @value{GDBN} to output a newline followed by two
34463@samp{control-z} characters, but if there was such a need, the
34464annotations could be extended with an @samp{escape} annotation which
34465means those three characters as output.
34466
086432e2
AC
34467The annotation @var{level}, which is specified using the
34468@option{--annotate} command line option (@pxref{Mode Options}), controls
34469how much information @value{GDBN} prints together with its prompt,
34470values of expressions, source lines, and other types of output. Level 0
d3e8051b 34471is for no annotations, level 1 is for use when @value{GDBN} is run as a
086432e2
AC
34472subprocess of @sc{gnu} Emacs, level 3 is the maximum annotation suitable
34473for programs that control @value{GDBN}, and level 2 annotations have
34474been made obsolete (@pxref{Limitations, , Limitations of the Annotation
09d4efe1
EZ
34475Interface, annotate, GDB's Obsolete Annotations}).
34476
34477@table @code
34478@kindex set annotate
34479@item set annotate @var{level}
e09f16f9 34480The @value{GDBN} command @code{set annotate} sets the level of
09d4efe1 34481annotations to the specified @var{level}.
9c16f35a
EZ
34482
34483@item show annotate
34484@kindex show annotate
34485Show the current annotation level.
09d4efe1
EZ
34486@end table
34487
34488This chapter describes level 3 annotations.
086432e2 34489
922fbb7b
AC
34490A simple example of starting up @value{GDBN} with annotations is:
34491
34492@smallexample
086432e2
AC
34493$ @kbd{gdb --annotate=3}
34494GNU gdb 6.0
34495Copyright 2003 Free Software Foundation, Inc.
922fbb7b
AC
34496GDB is free software, covered by the GNU General Public License,
34497and you are welcome to change it and/or distribute copies of it
34498under certain conditions.
34499Type "show copying" to see the conditions.
34500There is absolutely no warranty for GDB. Type "show warranty"
34501for details.
086432e2 34502This GDB was configured as "i386-pc-linux-gnu"
922fbb7b
AC
34503
34504^Z^Zpre-prompt
f7dc1244 34505(@value{GDBP})
922fbb7b 34506^Z^Zprompt
086432e2 34507@kbd{quit}
922fbb7b
AC
34508
34509^Z^Zpost-prompt
b383017d 34510$
922fbb7b
AC
34511@end smallexample
34512
34513Here @samp{quit} is input to @value{GDBN}; the rest is output from
34514@value{GDBN}. The three lines beginning @samp{^Z^Z} (where @samp{^Z}
34515denotes a @samp{control-z} character) are annotations; the rest is
34516output from @value{GDBN}.
34517
9e6c4bd5
NR
34518@node Server Prefix
34519@section The Server Prefix
34520@cindex server prefix
34521
34522If you prefix a command with @samp{server } then it will not affect
34523the command history, nor will it affect @value{GDBN}'s notion of which
34524command to repeat if @key{RET} is pressed on a line by itself. This
34525means that commands can be run behind a user's back by a front-end in
34526a transparent manner.
34527
d837706a
NR
34528The @code{server } prefix does not affect the recording of values into
34529the value history; to print a value without recording it into the
34530value history, use the @code{output} command instead of the
34531@code{print} command.
34532
34533Using this prefix also disables confirmation requests
34534(@pxref{confirmation requests}).
9e6c4bd5 34535
922fbb7b
AC
34536@node Prompting
34537@section Annotation for @value{GDBN} Input
34538
34539@cindex annotations for prompts
34540When @value{GDBN} prompts for input, it annotates this fact so it is possible
34541to know when to send output, when the output from a given command is
34542over, etc.
34543
34544Different kinds of input each have a different @dfn{input type}. Each
34545input type has three annotations: a @code{pre-} annotation, which
34546denotes the beginning of any prompt which is being output, a plain
34547annotation, which denotes the end of the prompt, and then a @code{post-}
34548annotation which denotes the end of any echo which may (or may not) be
34549associated with the input. For example, the @code{prompt} input type
34550features the following annotations:
34551
34552@smallexample
34553^Z^Zpre-prompt
34554^Z^Zprompt
34555^Z^Zpost-prompt
34556@end smallexample
34557
34558The input types are
34559
34560@table @code
e5ac9b53
EZ
34561@findex pre-prompt annotation
34562@findex prompt annotation
34563@findex post-prompt annotation
922fbb7b
AC
34564@item prompt
34565When @value{GDBN} is prompting for a command (the main @value{GDBN} prompt).
34566
e5ac9b53
EZ
34567@findex pre-commands annotation
34568@findex commands annotation
34569@findex post-commands annotation
922fbb7b
AC
34570@item commands
34571When @value{GDBN} prompts for a set of commands, like in the @code{commands}
34572command. The annotations are repeated for each command which is input.
34573
e5ac9b53
EZ
34574@findex pre-overload-choice annotation
34575@findex overload-choice annotation
34576@findex post-overload-choice annotation
922fbb7b
AC
34577@item overload-choice
34578When @value{GDBN} wants the user to select between various overloaded functions.
34579
e5ac9b53
EZ
34580@findex pre-query annotation
34581@findex query annotation
34582@findex post-query annotation
922fbb7b
AC
34583@item query
34584When @value{GDBN} wants the user to confirm a potentially dangerous operation.
34585
e5ac9b53
EZ
34586@findex pre-prompt-for-continue annotation
34587@findex prompt-for-continue annotation
34588@findex post-prompt-for-continue annotation
922fbb7b
AC
34589@item prompt-for-continue
34590When @value{GDBN} is asking the user to press return to continue. Note: Don't
34591expect this to work well; instead use @code{set height 0} to disable
34592prompting. This is because the counting of lines is buggy in the
34593presence of annotations.
34594@end table
34595
34596@node Errors
34597@section Errors
34598@cindex annotations for errors, warnings and interrupts
34599
e5ac9b53 34600@findex quit annotation
922fbb7b
AC
34601@smallexample
34602^Z^Zquit
34603@end smallexample
34604
34605This annotation occurs right before @value{GDBN} responds to an interrupt.
34606
e5ac9b53 34607@findex error annotation
922fbb7b
AC
34608@smallexample
34609^Z^Zerror
34610@end smallexample
34611
34612This annotation occurs right before @value{GDBN} responds to an error.
34613
34614Quit and error annotations indicate that any annotations which @value{GDBN} was
34615in the middle of may end abruptly. For example, if a
34616@code{value-history-begin} annotation is followed by a @code{error}, one
34617cannot expect to receive the matching @code{value-history-end}. One
34618cannot expect not to receive it either, however; an error annotation
34619does not necessarily mean that @value{GDBN} is immediately returning all the way
34620to the top level.
34621
e5ac9b53 34622@findex error-begin annotation
922fbb7b
AC
34623A quit or error annotation may be preceded by
34624
34625@smallexample
34626^Z^Zerror-begin
34627@end smallexample
34628
34629Any output between that and the quit or error annotation is the error
34630message.
34631
34632Warning messages are not yet annotated.
34633@c If we want to change that, need to fix warning(), type_error(),
34634@c range_error(), and possibly other places.
34635
922fbb7b
AC
34636@node Invalidation
34637@section Invalidation Notices
34638
34639@cindex annotations for invalidation messages
34640The following annotations say that certain pieces of state may have
34641changed.
34642
34643@table @code
e5ac9b53 34644@findex frames-invalid annotation
922fbb7b
AC
34645@item ^Z^Zframes-invalid
34646
34647The frames (for example, output from the @code{backtrace} command) may
34648have changed.
34649
e5ac9b53 34650@findex breakpoints-invalid annotation
922fbb7b
AC
34651@item ^Z^Zbreakpoints-invalid
34652
34653The breakpoints may have changed. For example, the user just added or
34654deleted a breakpoint.
34655@end table
34656
34657@node Annotations for Running
34658@section Running the Program
34659@cindex annotations for running programs
34660
e5ac9b53
EZ
34661@findex starting annotation
34662@findex stopping annotation
922fbb7b 34663When the program starts executing due to a @value{GDBN} command such as
b383017d 34664@code{step} or @code{continue},
922fbb7b
AC
34665
34666@smallexample
34667^Z^Zstarting
34668@end smallexample
34669
b383017d 34670is output. When the program stops,
922fbb7b
AC
34671
34672@smallexample
34673^Z^Zstopped
34674@end smallexample
34675
34676is output. Before the @code{stopped} annotation, a variety of
34677annotations describe how the program stopped.
34678
34679@table @code
e5ac9b53 34680@findex exited annotation
922fbb7b
AC
34681@item ^Z^Zexited @var{exit-status}
34682The program exited, and @var{exit-status} is the exit status (zero for
34683successful exit, otherwise nonzero).
34684
e5ac9b53
EZ
34685@findex signalled annotation
34686@findex signal-name annotation
34687@findex signal-name-end annotation
34688@findex signal-string annotation
34689@findex signal-string-end annotation
922fbb7b
AC
34690@item ^Z^Zsignalled
34691The program exited with a signal. After the @code{^Z^Zsignalled}, the
34692annotation continues:
34693
34694@smallexample
34695@var{intro-text}
34696^Z^Zsignal-name
34697@var{name}
34698^Z^Zsignal-name-end
34699@var{middle-text}
34700^Z^Zsignal-string
34701@var{string}
34702^Z^Zsignal-string-end
34703@var{end-text}
34704@end smallexample
34705
34706@noindent
34707where @var{name} is the name of the signal, such as @code{SIGILL} or
34708@code{SIGSEGV}, and @var{string} is the explanation of the signal, such
697aa1b7 34709as @code{Illegal Instruction} or @code{Segmentation fault}. The arguments
922fbb7b
AC
34710@var{intro-text}, @var{middle-text}, and @var{end-text} are for the
34711user's benefit and have no particular format.
34712
e5ac9b53 34713@findex signal annotation
922fbb7b
AC
34714@item ^Z^Zsignal
34715The syntax of this annotation is just like @code{signalled}, but @value{GDBN} is
34716just saying that the program received the signal, not that it was
34717terminated with it.
34718
e5ac9b53 34719@findex breakpoint annotation
922fbb7b
AC
34720@item ^Z^Zbreakpoint @var{number}
34721The program hit breakpoint number @var{number}.
34722
e5ac9b53 34723@findex watchpoint annotation
922fbb7b
AC
34724@item ^Z^Zwatchpoint @var{number}
34725The program hit watchpoint number @var{number}.
34726@end table
34727
34728@node Source Annotations
34729@section Displaying Source
34730@cindex annotations for source display
34731
e5ac9b53 34732@findex source annotation
922fbb7b
AC
34733The following annotation is used instead of displaying source code:
34734
34735@smallexample
34736^Z^Zsource @var{filename}:@var{line}:@var{character}:@var{middle}:@var{addr}
34737@end smallexample
34738
34739where @var{filename} is an absolute file name indicating which source
34740file, @var{line} is the line number within that file (where 1 is the
34741first line in the file), @var{character} is the character position
34742within the file (where 0 is the first character in the file) (for most
34743debug formats this will necessarily point to the beginning of a line),
34744@var{middle} is @samp{middle} if @var{addr} is in the middle of the
34745line, or @samp{beg} if @var{addr} is at the beginning of the line, and
34746@var{addr} is the address in the target program associated with the
697aa1b7 34747source which is being displayed. The @var{addr} is in the form @samp{0x}
922fbb7b
AC
34748followed by one or more lowercase hex digits (note that this does not
34749depend on the language).
34750
4efc6507
DE
34751@node JIT Interface
34752@chapter JIT Compilation Interface
34753@cindex just-in-time compilation
34754@cindex JIT compilation interface
34755
34756This chapter documents @value{GDBN}'s @dfn{just-in-time} (JIT) compilation
34757interface. A JIT compiler is a program or library that generates native
34758executable code at runtime and executes it, usually in order to achieve good
34759performance while maintaining platform independence.
34760
34761Programs that use JIT compilation are normally difficult to debug because
34762portions of their code are generated at runtime, instead of being loaded from
34763object files, which is where @value{GDBN} normally finds the program's symbols
34764and debug information. In order to debug programs that use JIT compilation,
34765@value{GDBN} has an interface that allows the program to register in-memory
34766symbol files with @value{GDBN} at runtime.
34767
34768If you are using @value{GDBN} to debug a program that uses this interface, then
34769it should work transparently so long as you have not stripped the binary. If
34770you are developing a JIT compiler, then the interface is documented in the rest
34771of this chapter. At this time, the only known client of this interface is the
34772LLVM JIT.
34773
34774Broadly speaking, the JIT interface mirrors the dynamic loader interface. The
34775JIT compiler communicates with @value{GDBN} by writing data into a global
34776variable and calling a fuction at a well-known symbol. When @value{GDBN}
34777attaches, it reads a linked list of symbol files from the global variable to
34778find existing code, and puts a breakpoint in the function so that it can find
34779out about additional code.
34780
34781@menu
34782* Declarations:: Relevant C struct declarations
34783* Registering Code:: Steps to register code
34784* Unregistering Code:: Steps to unregister code
f85b53f8 34785* Custom Debug Info:: Emit debug information in a custom format
4efc6507
DE
34786@end menu
34787
34788@node Declarations
34789@section JIT Declarations
34790
34791These are the relevant struct declarations that a C program should include to
34792implement the interface:
34793
34794@smallexample
34795typedef enum
34796@{
34797 JIT_NOACTION = 0,
34798 JIT_REGISTER_FN,
34799 JIT_UNREGISTER_FN
34800@} jit_actions_t;
34801
34802struct jit_code_entry
34803@{
34804 struct jit_code_entry *next_entry;
34805 struct jit_code_entry *prev_entry;
34806 const char *symfile_addr;
34807 uint64_t symfile_size;
34808@};
34809
34810struct jit_descriptor
34811@{
34812 uint32_t version;
34813 /* This type should be jit_actions_t, but we use uint32_t
34814 to be explicit about the bitwidth. */
34815 uint32_t action_flag;
34816 struct jit_code_entry *relevant_entry;
34817 struct jit_code_entry *first_entry;
34818@};
34819
34820/* GDB puts a breakpoint in this function. */
34821void __attribute__((noinline)) __jit_debug_register_code() @{ @};
34822
34823/* Make sure to specify the version statically, because the
34824 debugger may check the version before we can set it. */
34825struct jit_descriptor __jit_debug_descriptor = @{ 1, 0, 0, 0 @};
34826@end smallexample
34827
34828If the JIT is multi-threaded, then it is important that the JIT synchronize any
34829modifications to this global data properly, which can easily be done by putting
34830a global mutex around modifications to these structures.
34831
34832@node Registering Code
34833@section Registering Code
34834
34835To register code with @value{GDBN}, the JIT should follow this protocol:
34836
34837@itemize @bullet
34838@item
34839Generate an object file in memory with symbols and other desired debug
34840information. The file must include the virtual addresses of the sections.
34841
34842@item
34843Create a code entry for the file, which gives the start and size of the symbol
34844file.
34845
34846@item
34847Add it to the linked list in the JIT descriptor.
34848
34849@item
34850Point the relevant_entry field of the descriptor at the entry.
34851
34852@item
34853Set @code{action_flag} to @code{JIT_REGISTER} and call
34854@code{__jit_debug_register_code}.
34855@end itemize
34856
34857When @value{GDBN} is attached and the breakpoint fires, @value{GDBN} uses the
34858@code{relevant_entry} pointer so it doesn't have to walk the list looking for
34859new code. However, the linked list must still be maintained in order to allow
34860@value{GDBN} to attach to a running process and still find the symbol files.
34861
34862@node Unregistering Code
34863@section Unregistering Code
34864
34865If code is freed, then the JIT should use the following protocol:
34866
34867@itemize @bullet
34868@item
34869Remove the code entry corresponding to the code from the linked list.
34870
34871@item
34872Point the @code{relevant_entry} field of the descriptor at the code entry.
34873
34874@item
34875Set @code{action_flag} to @code{JIT_UNREGISTER} and call
34876@code{__jit_debug_register_code}.
34877@end itemize
34878
34879If the JIT frees or recompiles code without unregistering it, then @value{GDBN}
34880and the JIT will leak the memory used for the associated symbol files.
34881
f85b53f8
SD
34882@node Custom Debug Info
34883@section Custom Debug Info
34884@cindex custom JIT debug info
34885@cindex JIT debug info reader
34886
34887Generating debug information in platform-native file formats (like ELF
34888or COFF) may be an overkill for JIT compilers; especially if all the
34889debug info is used for is displaying a meaningful backtrace. The
34890issue can be resolved by having the JIT writers decide on a debug info
34891format and also provide a reader that parses the debug info generated
34892by the JIT compiler. This section gives a brief overview on writing
34893such a parser. More specific details can be found in the source file
34894@file{gdb/jit-reader.in}, which is also installed as a header at
34895@file{@var{includedir}/gdb/jit-reader.h} for easy inclusion.
34896
34897The reader is implemented as a shared object (so this functionality is
34898not available on platforms which don't allow loading shared objects at
34899runtime). Two @value{GDBN} commands, @code{jit-reader-load} and
34900@code{jit-reader-unload} are provided, to be used to load and unload
34901the readers from a preconfigured directory. Once loaded, the shared
34902object is used the parse the debug information emitted by the JIT
34903compiler.
34904
34905@menu
34906* Using JIT Debug Info Readers:: How to use supplied readers correctly
34907* Writing JIT Debug Info Readers:: Creating a debug-info reader
34908@end menu
34909
34910@node Using JIT Debug Info Readers
34911@subsection Using JIT Debug Info Readers
34912@kindex jit-reader-load
34913@kindex jit-reader-unload
34914
34915Readers can be loaded and unloaded using the @code{jit-reader-load}
34916and @code{jit-reader-unload} commands.
34917
34918@table @code
c9fb1240 34919@item jit-reader-load @var{reader}
697aa1b7 34920Load the JIT reader named @var{reader}, which is a shared
c9fb1240
SD
34921object specified as either an absolute or a relative file name. In
34922the latter case, @value{GDBN} will try to load the reader from a
34923pre-configured directory, usually @file{@var{libdir}/gdb/} on a UNIX
34924system (here @var{libdir} is the system library directory, often
34925@file{/usr/local/lib}).
34926
34927Only one reader can be active at a time; trying to load a second
34928reader when one is already loaded will result in @value{GDBN}
34929reporting an error. A new JIT reader can be loaded by first unloading
34930the current one using @code{jit-reader-unload} and then invoking
34931@code{jit-reader-load}.
f85b53f8
SD
34932
34933@item jit-reader-unload
34934Unload the currently loaded JIT reader.
34935
34936@end table
34937
34938@node Writing JIT Debug Info Readers
34939@subsection Writing JIT Debug Info Readers
34940@cindex writing JIT debug info readers
34941
34942As mentioned, a reader is essentially a shared object conforming to a
34943certain ABI. This ABI is described in @file{jit-reader.h}.
34944
34945@file{jit-reader.h} defines the structures, macros and functions
34946required to write a reader. It is installed (along with
34947@value{GDBN}), in @file{@var{includedir}/gdb} where @var{includedir} is
34948the system include directory.
34949
34950Readers need to be released under a GPL compatible license. A reader
34951can be declared as released under such a license by placing the macro
34952@code{GDB_DECLARE_GPL_COMPATIBLE_READER} in a source file.
34953
34954The entry point for readers is the symbol @code{gdb_init_reader},
34955which is expected to be a function with the prototype
34956
34957@findex gdb_init_reader
34958@smallexample
34959extern struct gdb_reader_funcs *gdb_init_reader (void);
34960@end smallexample
34961
34962@cindex @code{struct gdb_reader_funcs}
34963
34964@code{struct gdb_reader_funcs} contains a set of pointers to callback
34965functions. These functions are executed to read the debug info
34966generated by the JIT compiler (@code{read}), to unwind stack frames
34967(@code{unwind}) and to create canonical frame IDs
34968(@code{get_Frame_id}). It also has a callback that is called when the
34969reader is being unloaded (@code{destroy}). The struct looks like this
34970
34971@smallexample
34972struct gdb_reader_funcs
34973@{
34974 /* Must be set to GDB_READER_INTERFACE_VERSION. */
34975 int reader_version;
34976
34977 /* For use by the reader. */
34978 void *priv_data;
34979
34980 gdb_read_debug_info *read;
34981 gdb_unwind_frame *unwind;
34982 gdb_get_frame_id *get_frame_id;
34983 gdb_destroy_reader *destroy;
34984@};
34985@end smallexample
34986
34987@cindex @code{struct gdb_symbol_callbacks}
34988@cindex @code{struct gdb_unwind_callbacks}
34989
34990The callbacks are provided with another set of callbacks by
34991@value{GDBN} to do their job. For @code{read}, these callbacks are
34992passed in a @code{struct gdb_symbol_callbacks} and for @code{unwind}
34993and @code{get_frame_id}, in a @code{struct gdb_unwind_callbacks}.
34994@code{struct gdb_symbol_callbacks} has callbacks to create new object
34995files and new symbol tables inside those object files. @code{struct
34996gdb_unwind_callbacks} has callbacks to read registers off the current
34997frame and to write out the values of the registers in the previous
34998frame. Both have a callback (@code{target_read}) to read bytes off the
34999target's address space.
35000
d1feda86
YQ
35001@node In-Process Agent
35002@chapter In-Process Agent
35003@cindex debugging agent
35004The traditional debugging model is conceptually low-speed, but works fine,
35005because most bugs can be reproduced in debugging-mode execution. However,
35006as multi-core or many-core processors are becoming mainstream, and
35007multi-threaded programs become more and more popular, there should be more
35008and more bugs that only manifest themselves at normal-mode execution, for
35009example, thread races, because debugger's interference with the program's
35010timing may conceal the bugs. On the other hand, in some applications,
35011it is not feasible for the debugger to interrupt the program's execution
35012long enough for the developer to learn anything helpful about its behavior.
35013If the program's correctness depends on its real-time behavior, delays
35014introduced by a debugger might cause the program to fail, even when the
35015code itself is correct. It is useful to be able to observe the program's
35016behavior without interrupting it.
35017
35018Therefore, traditional debugging model is too intrusive to reproduce
35019some bugs. In order to reduce the interference with the program, we can
35020reduce the number of operations performed by debugger. The
35021@dfn{In-Process Agent}, a shared library, is running within the same
35022process with inferior, and is able to perform some debugging operations
35023itself. As a result, debugger is only involved when necessary, and
35024performance of debugging can be improved accordingly. Note that
35025interference with program can be reduced but can't be removed completely,
35026because the in-process agent will still stop or slow down the program.
35027
35028The in-process agent can interpret and execute Agent Expressions
35029(@pxref{Agent Expressions}) during performing debugging operations. The
35030agent expressions can be used for different purposes, such as collecting
35031data in tracepoints, and condition evaluation in breakpoints.
35032
35033@anchor{Control Agent}
35034You can control whether the in-process agent is used as an aid for
35035debugging with the following commands:
35036
35037@table @code
35038@kindex set agent on
35039@item set agent on
35040Causes the in-process agent to perform some operations on behalf of the
35041debugger. Just which operations requested by the user will be done
35042by the in-process agent depends on the its capabilities. For example,
35043if you request to evaluate breakpoint conditions in the in-process agent,
35044and the in-process agent has such capability as well, then breakpoint
35045conditions will be evaluated in the in-process agent.
35046
35047@kindex set agent off
35048@item set agent off
35049Disables execution of debugging operations by the in-process agent. All
35050of the operations will be performed by @value{GDBN}.
35051
35052@kindex show agent
35053@item show agent
35054Display the current setting of execution of debugging operations by
35055the in-process agent.
35056@end table
35057
16bdd41f
YQ
35058@menu
35059* In-Process Agent Protocol::
35060@end menu
35061
35062@node In-Process Agent Protocol
35063@section In-Process Agent Protocol
35064@cindex in-process agent protocol
35065
35066The in-process agent is able to communicate with both @value{GDBN} and
35067GDBserver (@pxref{In-Process Agent}). This section documents the protocol
35068used for communications between @value{GDBN} or GDBserver and the IPA.
35069In general, @value{GDBN} or GDBserver sends commands
35070(@pxref{IPA Protocol Commands}) and data to in-process agent, and then
35071in-process agent replies back with the return result of the command, or
35072some other information. The data sent to in-process agent is composed
35073of primitive data types, such as 4-byte or 8-byte type, and composite
35074types, which are called objects (@pxref{IPA Protocol Objects}).
35075
35076@menu
35077* IPA Protocol Objects::
35078* IPA Protocol Commands::
35079@end menu
35080
35081@node IPA Protocol Objects
35082@subsection IPA Protocol Objects
35083@cindex ipa protocol objects
35084
35085The commands sent to and results received from agent may contain some
35086complex data types called @dfn{objects}.
35087
35088The in-process agent is running on the same machine with @value{GDBN}
35089or GDBserver, so it doesn't have to handle as much differences between
35090two ends as remote protocol (@pxref{Remote Protocol}) tries to handle.
35091However, there are still some differences of two ends in two processes:
35092
35093@enumerate
35094@item
35095word size. On some 64-bit machines, @value{GDBN} or GDBserver can be
35096compiled as a 64-bit executable, while in-process agent is a 32-bit one.
35097@item
35098ABI. Some machines may have multiple types of ABI, @value{GDBN} or
35099GDBserver is compiled with one, and in-process agent is compiled with
35100the other one.
35101@end enumerate
35102
35103Here are the IPA Protocol Objects:
35104
35105@enumerate
35106@item
35107agent expression object. It represents an agent expression
35108(@pxref{Agent Expressions}).
35109@anchor{agent expression object}
35110@item
35111tracepoint action object. It represents a tracepoint action
35112(@pxref{Tracepoint Actions,,Tracepoint Action Lists}) to collect registers,
35113memory, static trace data and to evaluate expression.
35114@anchor{tracepoint action object}
35115@item
35116tracepoint object. It represents a tracepoint (@pxref{Tracepoints}).
35117@anchor{tracepoint object}
35118
35119@end enumerate
35120
35121The following table describes important attributes of each IPA protocol
35122object:
35123
35124@multitable @columnfractions .30 .20 .50
35125@headitem Name @tab Size @tab Description
35126@item @emph{agent expression object} @tab @tab
35127@item length @tab 4 @tab length of bytes code
35128@item byte code @tab @var{length} @tab contents of byte code
35129@item @emph{tracepoint action for collecting memory} @tab @tab
35130@item 'M' @tab 1 @tab type of tracepoint action
35131@item addr @tab 8 @tab if @var{basereg} is @samp{-1}, @var{addr} is the
35132address of the lowest byte to collect, otherwise @var{addr} is the offset
35133of @var{basereg} for memory collecting.
35134@item len @tab 8 @tab length of memory for collecting
35135@item basereg @tab 4 @tab the register number containing the starting
35136memory address for collecting.
35137@item @emph{tracepoint action for collecting registers} @tab @tab
35138@item 'R' @tab 1 @tab type of tracepoint action
35139@item @emph{tracepoint action for collecting static trace data} @tab @tab
35140@item 'L' @tab 1 @tab type of tracepoint action
35141@item @emph{tracepoint action for expression evaluation} @tab @tab
35142@item 'X' @tab 1 @tab type of tracepoint action
35143@item agent expression @tab length of @tab @ref{agent expression object}
35144@item @emph{tracepoint object} @tab @tab
35145@item number @tab 4 @tab number of tracepoint
35146@item address @tab 8 @tab address of tracepoint inserted on
35147@item type @tab 4 @tab type of tracepoint
35148@item enabled @tab 1 @tab enable or disable of tracepoint
35149@item step_count @tab 8 @tab step
35150@item pass_count @tab 8 @tab pass
35151@item numactions @tab 4 @tab number of tracepoint actions
35152@item hit count @tab 8 @tab hit count
35153@item trace frame usage @tab 8 @tab trace frame usage
35154@item compiled_cond @tab 8 @tab compiled condition
35155@item orig_size @tab 8 @tab orig size
35156@item condition @tab 4 if condition is NULL otherwise length of
35157@ref{agent expression object}
35158@tab zero if condition is NULL, otherwise is
35159@ref{agent expression object}
35160@item actions @tab variable
35161@tab numactions number of @ref{tracepoint action object}
35162@end multitable
35163
35164@node IPA Protocol Commands
35165@subsection IPA Protocol Commands
35166@cindex ipa protocol commands
35167
35168The spaces in each command are delimiters to ease reading this commands
35169specification. They don't exist in real commands.
35170
35171@table @samp
35172
35173@item FastTrace:@var{tracepoint_object} @var{gdb_jump_pad_head}
35174Installs a new fast tracepoint described by @var{tracepoint_object}
697aa1b7 35175(@pxref{tracepoint object}). The @var{gdb_jump_pad_head}, 8-byte long, is the
16bdd41f
YQ
35176head of @dfn{jumppad}, which is used to jump to data collection routine
35177in IPA finally.
35178
35179Replies:
35180@table @samp
35181@item OK @var{target_address} @var{gdb_jump_pad_head} @var{fjump_size} @var{fjump}
35182@var{target_address} is address of tracepoint in the inferior.
697aa1b7 35183The @var{gdb_jump_pad_head} is updated head of jumppad. Both of
16bdd41f 35184@var{target_address} and @var{gdb_jump_pad_head} are 8-byte long.
697aa1b7
EZ
35185The @var{fjump} contains a sequence of instructions jump to jumppad entry.
35186The @var{fjump_size}, 4-byte long, is the size of @var{fjump}.
16bdd41f
YQ
35187@item E @var{NN}
35188for an error
35189
35190@end table
35191
7255706c
YQ
35192@item close
35193Closes the in-process agent. This command is sent when @value{GDBN} or GDBserver
35194is about to kill inferiors.
35195
16bdd41f
YQ
35196@item qTfSTM
35197@xref{qTfSTM}.
35198@item qTsSTM
35199@xref{qTsSTM}.
35200@item qTSTMat
35201@xref{qTSTMat}.
35202@item probe_marker_at:@var{address}
35203Asks in-process agent to probe the marker at @var{address}.
35204
35205Replies:
35206@table @samp
35207@item E @var{NN}
35208for an error
35209@end table
35210@item unprobe_marker_at:@var{address}
35211Asks in-process agent to unprobe the marker at @var{address}.
35212@end table
35213
8e04817f
AC
35214@node GDB Bugs
35215@chapter Reporting Bugs in @value{GDBN}
35216@cindex bugs in @value{GDBN}
35217@cindex reporting bugs in @value{GDBN}
c906108c 35218
8e04817f 35219Your bug reports play an essential role in making @value{GDBN} reliable.
c906108c 35220
8e04817f
AC
35221Reporting a bug may help you by bringing a solution to your problem, or it
35222may not. But in any case the principal function of a bug report is to help
35223the entire community by making the next version of @value{GDBN} work better. Bug
35224reports are your contribution to the maintenance of @value{GDBN}.
c906108c 35225
8e04817f
AC
35226In order for a bug report to serve its purpose, you must include the
35227information that enables us to fix the bug.
c4555f82
SC
35228
35229@menu
8e04817f
AC
35230* Bug Criteria:: Have you found a bug?
35231* Bug Reporting:: How to report bugs
c4555f82
SC
35232@end menu
35233
8e04817f 35234@node Bug Criteria
79a6e687 35235@section Have You Found a Bug?
8e04817f 35236@cindex bug criteria
c4555f82 35237
8e04817f 35238If you are not sure whether you have found a bug, here are some guidelines:
c4555f82
SC
35239
35240@itemize @bullet
8e04817f
AC
35241@cindex fatal signal
35242@cindex debugger crash
35243@cindex crash of debugger
c4555f82 35244@item
8e04817f
AC
35245If the debugger gets a fatal signal, for any input whatever, that is a
35246@value{GDBN} bug. Reliable debuggers never crash.
35247
35248@cindex error on valid input
35249@item
35250If @value{GDBN} produces an error message for valid input, that is a
35251bug. (Note that if you're cross debugging, the problem may also be
35252somewhere in the connection to the target.)
c4555f82 35253
8e04817f 35254@cindex invalid input
c4555f82 35255@item
8e04817f
AC
35256If @value{GDBN} does not produce an error message for invalid input,
35257that is a bug. However, you should note that your idea of
35258``invalid input'' might be our idea of ``an extension'' or ``support
35259for traditional practice''.
35260
35261@item
35262If you are an experienced user of debugging tools, your suggestions
35263for improvement of @value{GDBN} are welcome in any case.
c4555f82
SC
35264@end itemize
35265
8e04817f 35266@node Bug Reporting
79a6e687 35267@section How to Report Bugs
8e04817f
AC
35268@cindex bug reports
35269@cindex @value{GDBN} bugs, reporting
35270
35271A number of companies and individuals offer support for @sc{gnu} products.
35272If you obtained @value{GDBN} from a support organization, we recommend you
35273contact that organization first.
35274
35275You can find contact information for many support companies and
35276individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
35277distribution.
35278@c should add a web page ref...
35279
c16158bc
JM
35280@ifset BUGURL
35281@ifset BUGURL_DEFAULT
129188f6 35282In any event, we also recommend that you submit bug reports for
d3e8051b 35283@value{GDBN}. The preferred method is to submit them directly using
129188f6
AC
35284@uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web
35285page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can
35286be used.
8e04817f
AC
35287
35288@strong{Do not send bug reports to @samp{info-gdb}, or to
35289@samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do
35290not want to receive bug reports. Those that do have arranged to receive
35291@samp{bug-gdb}.
35292
35293The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which
35294serves as a repeater. The mailing list and the newsgroup carry exactly
35295the same messages. Often people think of posting bug reports to the
35296newsgroup instead of mailing them. This appears to work, but it has one
35297problem which can be crucial: a newsgroup posting often lacks a mail
35298path back to the sender. Thus, if we need to ask for more information,
35299we may be unable to reach you. For this reason, it is better to send
35300bug reports to the mailing list.
c16158bc
JM
35301@end ifset
35302@ifclear BUGURL_DEFAULT
35303In any event, we also recommend that you submit bug reports for
35304@value{GDBN} to @value{BUGURL}.
35305@end ifclear
35306@end ifset
c4555f82 35307
8e04817f
AC
35308The fundamental principle of reporting bugs usefully is this:
35309@strong{report all the facts}. If you are not sure whether to state a
35310fact or leave it out, state it!
c4555f82 35311
8e04817f
AC
35312Often people omit facts because they think they know what causes the
35313problem and assume that some details do not matter. Thus, you might
35314assume that the name of the variable you use in an example does not matter.
35315Well, probably it does not, but one cannot be sure. Perhaps the bug is a
35316stray memory reference which happens to fetch from the location where that
35317name is stored in memory; perhaps, if the name were different, the contents
35318of that location would fool the debugger into doing the right thing despite
35319the bug. Play it safe and give a specific, complete example. That is the
35320easiest thing for you to do, and the most helpful.
c4555f82 35321
8e04817f
AC
35322Keep in mind that the purpose of a bug report is to enable us to fix the
35323bug. It may be that the bug has been reported previously, but neither
35324you nor we can know that unless your bug report is complete and
35325self-contained.
c4555f82 35326
8e04817f
AC
35327Sometimes people give a few sketchy facts and ask, ``Does this ring a
35328bell?'' Those bug reports are useless, and we urge everyone to
35329@emph{refuse to respond to them} except to chide the sender to report
35330bugs properly.
35331
35332To enable us to fix the bug, you should include all these things:
c4555f82
SC
35333
35334@itemize @bullet
35335@item
8e04817f
AC
35336The version of @value{GDBN}. @value{GDBN} announces it if you start
35337with no arguments; you can also print it at any time using @code{show
35338version}.
c4555f82 35339
8e04817f
AC
35340Without this, we will not know whether there is any point in looking for
35341the bug in the current version of @value{GDBN}.
c4555f82
SC
35342
35343@item
8e04817f
AC
35344The type of machine you are using, and the operating system name and
35345version number.
c4555f82 35346
6eaaf48b
EZ
35347@item
35348The details of the @value{GDBN} build-time configuration.
35349@value{GDBN} shows these details if you invoke it with the
35350@option{--configuration} command-line option, or if you type
35351@code{show configuration} at @value{GDBN}'s prompt.
35352
c4555f82 35353@item
c1468174 35354What compiler (and its version) was used to compile @value{GDBN}---e.g.@:
8e04817f 35355``@value{GCC}--2.8.1''.
c4555f82
SC
35356
35357@item
8e04817f 35358What compiler (and its version) was used to compile the program you are
c1468174 35359debugging---e.g.@: ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP
3f94c067
BW
35360C Compiler''. For @value{NGCC}, you can say @kbd{@value{GCC} --version}
35361to get this information; for other compilers, see the documentation for
35362those compilers.
c4555f82 35363
8e04817f
AC
35364@item
35365The command arguments you gave the compiler to compile your example and
35366observe the bug. For example, did you use @samp{-O}? To guarantee
35367you will not omit something important, list them all. A copy of the
35368Makefile (or the output from make) is sufficient.
c4555f82 35369
8e04817f
AC
35370If we were to try to guess the arguments, we would probably guess wrong
35371and then we might not encounter the bug.
c4555f82 35372
8e04817f
AC
35373@item
35374A complete input script, and all necessary source files, that will
35375reproduce the bug.
c4555f82 35376
8e04817f
AC
35377@item
35378A description of what behavior you observe that you believe is
35379incorrect. For example, ``It gets a fatal signal.''
c4555f82 35380
8e04817f
AC
35381Of course, if the bug is that @value{GDBN} gets a fatal signal, then we
35382will certainly notice it. But if the bug is incorrect output, we might
35383not notice unless it is glaringly wrong. You might as well not give us
35384a chance to make a mistake.
c4555f82 35385
8e04817f
AC
35386Even if the problem you experience is a fatal signal, you should still
35387say so explicitly. Suppose something strange is going on, such as, your
35388copy of @value{GDBN} is out of synch, or you have encountered a bug in
35389the C library on your system. (This has happened!) Your copy might
35390crash and ours would not. If you told us to expect a crash, then when
35391ours fails to crash, we would know that the bug was not happening for
35392us. If you had not told us to expect a crash, then we would not be able
35393to draw any conclusion from our observations.
c4555f82 35394
e0c07bf0
MC
35395@pindex script
35396@cindex recording a session script
35397To collect all this information, you can use a session recording program
35398such as @command{script}, which is available on many Unix systems.
35399Just run your @value{GDBN} session inside @command{script} and then
35400include the @file{typescript} file with your bug report.
35401
35402Another way to record a @value{GDBN} session is to run @value{GDBN}
35403inside Emacs and then save the entire buffer to a file.
35404
8e04817f
AC
35405@item
35406If you wish to suggest changes to the @value{GDBN} source, send us context
35407diffs. If you even discuss something in the @value{GDBN} source, refer to
35408it by context, not by line number.
c4555f82 35409
8e04817f
AC
35410The line numbers in our development sources will not match those in your
35411sources. Your line numbers would convey no useful information to us.
c4555f82 35412
8e04817f 35413@end itemize
c4555f82 35414
8e04817f 35415Here are some things that are not necessary:
c4555f82 35416
8e04817f
AC
35417@itemize @bullet
35418@item
35419A description of the envelope of the bug.
c4555f82 35420
8e04817f
AC
35421Often people who encounter a bug spend a lot of time investigating
35422which changes to the input file will make the bug go away and which
35423changes will not affect it.
c4555f82 35424
8e04817f
AC
35425This is often time consuming and not very useful, because the way we
35426will find the bug is by running a single example under the debugger
35427with breakpoints, not by pure deduction from a series of examples.
35428We recommend that you save your time for something else.
c4555f82 35429
8e04817f
AC
35430Of course, if you can find a simpler example to report @emph{instead}
35431of the original one, that is a convenience for us. Errors in the
35432output will be easier to spot, running under the debugger will take
35433less time, and so on.
c4555f82 35434
8e04817f
AC
35435However, simplification is not vital; if you do not want to do this,
35436report the bug anyway and send us the entire test case you used.
c4555f82 35437
8e04817f
AC
35438@item
35439A patch for the bug.
c4555f82 35440
8e04817f
AC
35441A patch for the bug does help us if it is a good one. But do not omit
35442the necessary information, such as the test case, on the assumption that
35443a patch is all we need. We might see problems with your patch and decide
35444to fix the problem another way, or we might not understand it at all.
c4555f82 35445
8e04817f
AC
35446Sometimes with a program as complicated as @value{GDBN} it is very hard to
35447construct an example that will make the program follow a certain path
35448through the code. If you do not send us the example, we will not be able
35449to construct one, so we will not be able to verify that the bug is fixed.
c4555f82 35450
8e04817f
AC
35451And if we cannot understand what bug you are trying to fix, or why your
35452patch should be an improvement, we will not install it. A test case will
35453help us to understand.
c4555f82 35454
8e04817f
AC
35455@item
35456A guess about what the bug is or what it depends on.
c4555f82 35457
8e04817f
AC
35458Such guesses are usually wrong. Even we cannot guess right about such
35459things without first using the debugger to find the facts.
35460@end itemize
c4555f82 35461
8e04817f
AC
35462@c The readline documentation is distributed with the readline code
35463@c and consists of the two following files:
cc88a640
JK
35464@c rluser.texi
35465@c hsuser.texi
8e04817f
AC
35466@c Use -I with makeinfo to point to the appropriate directory,
35467@c environment var TEXINPUTS with TeX.
39037522 35468@ifclear SYSTEM_READLINE
5bdf8622 35469@include rluser.texi
cc88a640 35470@include hsuser.texi
39037522 35471@end ifclear
c4555f82 35472
4ceed123
JB
35473@node In Memoriam
35474@appendix In Memoriam
35475
9ed350ad
JB
35476The @value{GDBN} project mourns the loss of the following long-time
35477contributors:
4ceed123
JB
35478
35479@table @code
35480@item Fred Fish
9ed350ad
JB
35481Fred was a long-standing contributor to @value{GDBN} (1991-2006), and
35482to Free Software in general. Outside of @value{GDBN}, he was known in
35483the Amiga world for his series of Fish Disks, and the GeekGadget project.
4ceed123
JB
35484
35485@item Michael Snyder
9ed350ad
JB
35486Michael was one of the Global Maintainers of the @value{GDBN} project,
35487with contributions recorded as early as 1996, until 2011. In addition
35488to his day to day participation, he was a large driving force behind
35489adding Reverse Debugging to @value{GDBN}.
4ceed123
JB
35490@end table
35491
35492Beyond their technical contributions to the project, they were also
35493enjoyable members of the Free Software Community. We will miss them.
c4555f82 35494
8e04817f
AC
35495@node Formatting Documentation
35496@appendix Formatting Documentation
c4555f82 35497
8e04817f
AC
35498@cindex @value{GDBN} reference card
35499@cindex reference card
35500The @value{GDBN} 4 release includes an already-formatted reference card, ready
35501for printing with PostScript or Ghostscript, in the @file{gdb}
35502subdirectory of the main source directory@footnote{In
35503@file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN}
35504release.}. If you can use PostScript or Ghostscript with your printer,
35505you can print the reference card immediately with @file{refcard.ps}.
c4555f82 35506
8e04817f
AC
35507The release also includes the source for the reference card. You
35508can format it, using @TeX{}, by typing:
c4555f82 35509
474c8240 35510@smallexample
8e04817f 35511make refcard.dvi
474c8240 35512@end smallexample
c4555f82 35513
8e04817f
AC
35514The @value{GDBN} reference card is designed to print in @dfn{landscape}
35515mode on US ``letter'' size paper;
35516that is, on a sheet 11 inches wide by 8.5 inches
35517high. You will need to specify this form of printing as an option to
35518your @sc{dvi} output program.
c4555f82 35519
8e04817f 35520@cindex documentation
c4555f82 35521
8e04817f
AC
35522All the documentation for @value{GDBN} comes as part of the machine-readable
35523distribution. The documentation is written in Texinfo format, which is
35524a documentation system that uses a single source file to produce both
35525on-line information and a printed manual. You can use one of the Info
35526formatting commands to create the on-line version of the documentation
35527and @TeX{} (or @code{texi2roff}) to typeset the printed version.
c4555f82 35528
8e04817f
AC
35529@value{GDBN} includes an already formatted copy of the on-line Info
35530version of this manual in the @file{gdb} subdirectory. The main Info
35531file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to
35532subordinate files matching @samp{gdb.info*} in the same directory. If
35533necessary, you can print out these files, or read them with any editor;
35534but they are easier to read using the @code{info} subsystem in @sc{gnu}
35535Emacs or the standalone @code{info} program, available as part of the
35536@sc{gnu} Texinfo distribution.
c4555f82 35537
8e04817f
AC
35538If you want to format these Info files yourself, you need one of the
35539Info formatting programs, such as @code{texinfo-format-buffer} or
35540@code{makeinfo}.
c4555f82 35541
8e04817f
AC
35542If you have @code{makeinfo} installed, and are in the top level
35543@value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of
35544version @value{GDBVN}), you can make the Info file by typing:
c4555f82 35545
474c8240 35546@smallexample
8e04817f
AC
35547cd gdb
35548make gdb.info
474c8240 35549@end smallexample
c4555f82 35550
8e04817f
AC
35551If you want to typeset and print copies of this manual, you need @TeX{},
35552a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the
35553Texinfo definitions file.
c4555f82 35554
8e04817f
AC
35555@TeX{} is a typesetting program; it does not print files directly, but
35556produces output files called @sc{dvi} files. To print a typeset
35557document, you need a program to print @sc{dvi} files. If your system
35558has @TeX{} installed, chances are it has such a program. The precise
35559command to use depends on your system; @kbd{lpr -d} is common; another
35560(for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may
35561require a file name without any extension or a @samp{.dvi} extension.
c4555f82 35562
8e04817f
AC
35563@TeX{} also requires a macro definitions file called
35564@file{texinfo.tex}. This file tells @TeX{} how to typeset a document
35565written in Texinfo format. On its own, @TeX{} cannot either read or
35566typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB
35567and is located in the @file{gdb-@var{version-number}/texinfo}
35568directory.
c4555f82 35569
8e04817f 35570If you have @TeX{} and a @sc{dvi} printer program installed, you can
d3e8051b 35571typeset and print this manual. First switch to the @file{gdb}
8e04817f
AC
35572subdirectory of the main source directory (for example, to
35573@file{gdb-@value{GDBVN}/gdb}) and type:
c4555f82 35574
474c8240 35575@smallexample
8e04817f 35576make gdb.dvi
474c8240 35577@end smallexample
c4555f82 35578
8e04817f 35579Then give @file{gdb.dvi} to your @sc{dvi} printing program.
c4555f82 35580
8e04817f
AC
35581@node Installing GDB
35582@appendix Installing @value{GDBN}
8e04817f 35583@cindex installation
c4555f82 35584
7fa2210b
DJ
35585@menu
35586* Requirements:: Requirements for building @value{GDBN}
db2e3e2e 35587* Running Configure:: Invoking the @value{GDBN} @file{configure} script
7fa2210b
DJ
35588* Separate Objdir:: Compiling @value{GDBN} in another directory
35589* Config Names:: Specifying names for hosts and targets
35590* Configure Options:: Summary of options for configure
098b41a6 35591* System-wide configuration:: Having a system-wide init file
7fa2210b
DJ
35592@end menu
35593
35594@node Requirements
79a6e687 35595@section Requirements for Building @value{GDBN}
7fa2210b
DJ
35596@cindex building @value{GDBN}, requirements for
35597
35598Building @value{GDBN} requires various tools and packages to be available.
35599Other packages will be used only if they are found.
35600
79a6e687 35601@heading Tools/Packages Necessary for Building @value{GDBN}
7fa2210b 35602@table @asis
7f0bd420
TT
35603@item C@t{++}11 compiler
35604@value{GDBN} is written in C@t{++}11. It should be buildable with any
35605recent C@t{++}11 compiler, e.g.@: GCC.
7fa2210b 35606
7f0bd420
TT
35607@item GNU make
35608@value{GDBN}'s build system relies on features only found in the GNU
35609make program. Other variants of @code{make} will not work.
7fa2210b
DJ
35610@end table
35611
79a6e687 35612@heading Tools/Packages Optional for Building @value{GDBN}
7fa2210b
DJ
35613@table @asis
35614@item Expat
123dc839 35615@anchor{Expat}
7fa2210b
DJ
35616@value{GDBN} can use the Expat XML parsing library. This library may be
35617included with your operating system distribution; if it is not, you
35618can get the latest version from @url{http://expat.sourceforge.net}.
db2e3e2e 35619The @file{configure} script will search for this library in several
7fa2210b
DJ
35620standard locations; if it is installed in an unusual path, you can
35621use the @option{--with-libexpat-prefix} option to specify its location.
35622
9cceb671
DJ
35623Expat is used for:
35624
35625@itemize @bullet
35626@item
35627Remote protocol memory maps (@pxref{Memory Map Format})
35628@item
35629Target descriptions (@pxref{Target Descriptions})
35630@item
2268b414
JK
35631Remote shared library lists (@xref{Library List Format},
35632or alternatively @pxref{Library List Format for SVR4 Targets})
9cceb671
DJ
35633@item
35634MS-Windows shared libraries (@pxref{Shared Libraries})
b3b9301e
PA
35635@item
35636Traceframe info (@pxref{Traceframe Info Format})
2ae8c8e7 35637@item
f4abbc16
MM
35638Branch trace (@pxref{Branch Trace Format},
35639@pxref{Branch Trace Configuration Format})
9cceb671 35640@end itemize
7fa2210b 35641
7f0bd420
TT
35642@item Guile
35643@value{GDBN} can be scripted using GNU Guile. @xref{Guile}. By
35644default, @value{GDBN} will be compiled if the Guile libraries are
35645installed and are found by @file{configure}. You can use the
35646@code{--with-guile} option to request Guile, and pass either the Guile
35647version number or the file name of the relevant @code{pkg-config}
35648program to choose a particular version of Guile.
35649
35650@item iconv
35651@value{GDBN}'s features related to character sets (@pxref{Character
35652Sets}) require a functioning @code{iconv} implementation. If you are
35653on a GNU system, then this is provided by the GNU C Library. Some
35654other systems also provide a working @code{iconv}.
35655
35656If @value{GDBN} is using the @code{iconv} program which is installed
35657in a non-standard place, you will need to tell @value{GDBN} where to
35658find it. This is done with @option{--with-iconv-bin} which specifies
35659the directory that contains the @code{iconv} program. This program is
35660run in order to make a list of the available character sets.
35661
35662On systems without @code{iconv}, you can install GNU Libiconv. If
35663Libiconv is installed in a standard place, @value{GDBN} will
35664automatically use it if it is needed. If you have previously
35665installed Libiconv in a non-standard place, you can use the
35666@option{--with-libiconv-prefix} option to @file{configure}.
35667
35668@value{GDBN}'s top-level @file{configure} and @file{Makefile} will
35669arrange to build Libiconv if a directory named @file{libiconv} appears
35670in the top-most source directory. If Libiconv is built this way, and
35671if the operating system does not provide a suitable @code{iconv}
35672implementation, then the just-built library will automatically be used
35673by @value{GDBN}. One easy way to set this up is to download GNU
35674Libiconv, unpack it inside the top-level directory of the @value{GDBN}
35675source tree, and then rename the directory holding the Libiconv source
35676code to @samp{libiconv}.
35677
35678@item lzma
35679@value{GDBN} can support debugging sections that are compressed with
35680the LZMA library. @xref{MiniDebugInfo}. If this library is not
35681included with your operating system, you can find it in the xz package
35682at @url{http://tukaani.org/xz/}. If the LZMA library is available in
35683the usual place, then the @file{configure} script will use it
35684automatically. If it is installed in an unusual path, you can use the
35685@option{--with-lzma-prefix} option to specify its location.
35686
2400729e
UW
35687@item MPFR
35688@anchor{MPFR}
35689@value{GDBN} can use the GNU MPFR multiple-precision floating-point
35690library. This library may be included with your operating system
35691distribution; if it is not, you can get the latest version from
35692@url{http://www.mpfr.org}. The @file{configure} script will search
35693for this library in several standard locations; if it is installed
35694in an unusual path, you can use the @option{--with-libmpfr-prefix}
35695option to specify its location.
35696
35697GNU MPFR is used to emulate target floating-point arithmetic during
35698expression evaluation when the target uses different floating-point
35699formats than the host. If GNU MPFR it is not available, @value{GDBN}
35700will fall back to using host floating-point arithmetic.
35701
7f0bd420
TT
35702@item Python
35703@value{GDBN} can be scripted using Python language. @xref{Python}.
35704By default, @value{GDBN} will be compiled if the Python libraries are
35705installed and are found by @file{configure}. You can use the
35706@code{--with-python} option to request Python, and pass either the
35707file name of the relevant @code{python} executable, or the name of the
35708directory in which Python is installed, to choose a particular
35709installation of Python.
35710
31fffb02
CS
35711@item zlib
35712@cindex compressed debug sections
35713@value{GDBN} will use the @samp{zlib} library, if available, to read
35714compressed debug sections. Some linkers, such as GNU gold, are capable
35715of producing binaries with compressed debug sections. If @value{GDBN}
35716is compiled with @samp{zlib}, it will be able to read the debug
35717information in such binaries.
35718
35719The @samp{zlib} library is likely included with your operating system
35720distribution; if it is not, you can get the latest version from
35721@url{http://zlib.net}.
7fa2210b
DJ
35722@end table
35723
35724@node Running Configure
db2e3e2e 35725@section Invoking the @value{GDBN} @file{configure} Script
7fa2210b 35726@cindex configuring @value{GDBN}
db2e3e2e 35727@value{GDBN} comes with a @file{configure} script that automates the process
8e04817f
AC
35728of preparing @value{GDBN} for installation; you can then use @code{make} to
35729build the @code{gdb} program.
35730@iftex
35731@c irrelevant in info file; it's as current as the code it lives with.
35732@footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN},
35733look at the @file{README} file in the sources; we may have improved the
35734installation procedures since publishing this manual.}
35735@end iftex
c4555f82 35736
8e04817f
AC
35737The @value{GDBN} distribution includes all the source code you need for
35738@value{GDBN} in a single directory, whose name is usually composed by
35739appending the version number to @samp{gdb}.
c4555f82 35740
8e04817f
AC
35741For example, the @value{GDBN} version @value{GDBVN} distribution is in the
35742@file{gdb-@value{GDBVN}} directory. That directory contains:
c4555f82 35743
8e04817f
AC
35744@table @code
35745@item gdb-@value{GDBVN}/configure @r{(and supporting files)}
35746script for configuring @value{GDBN} and all its supporting libraries
c4555f82 35747
8e04817f
AC
35748@item gdb-@value{GDBVN}/gdb
35749the source specific to @value{GDBN} itself
c4555f82 35750
8e04817f
AC
35751@item gdb-@value{GDBVN}/bfd
35752source for the Binary File Descriptor library
c906108c 35753
8e04817f
AC
35754@item gdb-@value{GDBVN}/include
35755@sc{gnu} include files
c906108c 35756
8e04817f
AC
35757@item gdb-@value{GDBVN}/libiberty
35758source for the @samp{-liberty} free software library
c906108c 35759
8e04817f
AC
35760@item gdb-@value{GDBVN}/opcodes
35761source for the library of opcode tables and disassemblers
c906108c 35762
8e04817f
AC
35763@item gdb-@value{GDBVN}/readline
35764source for the @sc{gnu} command-line interface
8e04817f 35765@end table
c906108c 35766
7f0bd420
TT
35767There may be other subdirectories as well.
35768
db2e3e2e 35769The simplest way to configure and build @value{GDBN} is to run @file{configure}
8e04817f
AC
35770from the @file{gdb-@var{version-number}} source directory, which in
35771this example is the @file{gdb-@value{GDBVN}} directory.
c906108c 35772
8e04817f 35773First switch to the @file{gdb-@var{version-number}} source directory
db2e3e2e 35774if you are not already in it; then run @file{configure}. Pass the
8e04817f
AC
35775identifier for the platform on which @value{GDBN} will run as an
35776argument.
c906108c 35777
8e04817f 35778For example:
c906108c 35779
474c8240 35780@smallexample
8e04817f 35781cd gdb-@value{GDBVN}
7f0bd420 35782./configure
8e04817f 35783make
474c8240 35784@end smallexample
c906108c 35785
7f0bd420
TT
35786Running @samp{configure} and then running @code{make} builds the
35787included supporting libraries, then @code{gdb} itself. The configured
35788source files, and the binaries, are left in the corresponding source
35789directories.
c906108c 35790
8e04817f 35791@need 750
db2e3e2e 35792@file{configure} is a Bourne-shell (@code{/bin/sh}) script; if your
8e04817f
AC
35793system does not recognize this automatically when you run a different
35794shell, you may need to run @code{sh} on it explicitly:
c906108c 35795
474c8240 35796@smallexample
7f0bd420 35797sh configure
474c8240 35798@end smallexample
c906108c 35799
db2e3e2e 35800You should run the @file{configure} script from the top directory in the
94e91d6d 35801source tree, the @file{gdb-@var{version-number}} directory. If you run
db2e3e2e 35802@file{configure} from one of the subdirectories, you will configure only
94e91d6d 35803that subdirectory. That is usually not what you want. In particular,
db2e3e2e 35804if you run the first @file{configure} from the @file{gdb} subdirectory
94e91d6d
MC
35805of the @file{gdb-@var{version-number}} directory, you will omit the
35806configuration of @file{bfd}, @file{readline}, and other sibling
35807directories of the @file{gdb} subdirectory. This leads to build errors
35808about missing include files such as @file{bfd/bfd.h}.
c906108c 35809
7f0bd420
TT
35810You can install @code{@value{GDBN}} anywhere. The best way to do this
35811is to pass the @code{--prefix} option to @code{configure}, and then
35812install it with @code{make install}.
c906108c 35813
8e04817f 35814@node Separate Objdir
79a6e687 35815@section Compiling @value{GDBN} in Another Directory
c906108c 35816
8e04817f
AC
35817If you want to run @value{GDBN} versions for several host or target machines,
35818you need a different @code{gdb} compiled for each combination of
db2e3e2e 35819host and target. @file{configure} is designed to make this easy by
8e04817f
AC
35820allowing you to generate each configuration in a separate subdirectory,
35821rather than in the source directory. If your @code{make} program
35822handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running
35823@code{make} in each of these directories builds the @code{gdb}
35824program specified there.
c906108c 35825
db2e3e2e 35826To build @code{gdb} in a separate directory, run @file{configure}
8e04817f 35827with the @samp{--srcdir} option to specify where to find the source.
db2e3e2e
BW
35828(You also need to specify a path to find @file{configure}
35829itself from your working directory. If the path to @file{configure}
8e04817f
AC
35830would be the same as the argument to @samp{--srcdir}, you can leave out
35831the @samp{--srcdir} option; it is assumed.)
c906108c 35832
8e04817f
AC
35833For example, with version @value{GDBVN}, you can build @value{GDBN} in a
35834separate directory for a Sun 4 like this:
c906108c 35835
474c8240 35836@smallexample
8e04817f
AC
35837@group
35838cd gdb-@value{GDBVN}
35839mkdir ../gdb-sun4
35840cd ../gdb-sun4
7f0bd420 35841../gdb-@value{GDBVN}/configure
8e04817f
AC
35842make
35843@end group
474c8240 35844@end smallexample
c906108c 35845
db2e3e2e 35846When @file{configure} builds a configuration using a remote source
8e04817f
AC
35847directory, it creates a tree for the binaries with the same structure
35848(and using the same names) as the tree under the source directory. In
35849the example, you'd find the Sun 4 library @file{libiberty.a} in the
35850directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in
35851@file{gdb-sun4/gdb}.
c906108c 35852
94e91d6d
MC
35853Make sure that your path to the @file{configure} script has just one
35854instance of @file{gdb} in it. If your path to @file{configure} looks
35855like @file{../gdb-@value{GDBVN}/gdb/configure}, you are configuring only
35856one subdirectory of @value{GDBN}, not the whole package. This leads to
35857build errors about missing include files such as @file{bfd/bfd.h}.
35858
8e04817f
AC
35859One popular reason to build several @value{GDBN} configurations in separate
35860directories is to configure @value{GDBN} for cross-compiling (where
35861@value{GDBN} runs on one machine---the @dfn{host}---while debugging
35862programs that run on another machine---the @dfn{target}).
35863You specify a cross-debugging target by
db2e3e2e 35864giving the @samp{--target=@var{target}} option to @file{configure}.
c906108c 35865
8e04817f
AC
35866When you run @code{make} to build a program or library, you must run
35867it in a configured directory---whatever directory you were in when you
db2e3e2e 35868called @file{configure} (or one of its subdirectories).
c906108c 35869
db2e3e2e 35870The @code{Makefile} that @file{configure} generates in each source
8e04817f
AC
35871directory also runs recursively. If you type @code{make} in a source
35872directory such as @file{gdb-@value{GDBVN}} (or in a separate configured
35873directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you
35874will build all the required libraries, and then build GDB.
c906108c 35875
8e04817f
AC
35876When you have multiple hosts or targets configured in separate
35877directories, you can run @code{make} on them in parallel (for example,
35878if they are NFS-mounted on each of the hosts); they will not interfere
35879with each other.
c906108c 35880
8e04817f 35881@node Config Names
79a6e687 35882@section Specifying Names for Hosts and Targets
c906108c 35883
db2e3e2e 35884The specifications used for hosts and targets in the @file{configure}
8e04817f
AC
35885script are based on a three-part naming scheme, but some short predefined
35886aliases are also supported. The full naming scheme encodes three pieces
35887of information in the following pattern:
c906108c 35888
474c8240 35889@smallexample
8e04817f 35890@var{architecture}-@var{vendor}-@var{os}
474c8240 35891@end smallexample
c906108c 35892
8e04817f
AC
35893For example, you can use the alias @code{sun4} as a @var{host} argument,
35894or as the value for @var{target} in a @code{--target=@var{target}}
35895option. The equivalent full name is @samp{sparc-sun-sunos4}.
c906108c 35896
db2e3e2e 35897The @file{configure} script accompanying @value{GDBN} does not provide
8e04817f 35898any query facility to list all supported host and target names or
db2e3e2e 35899aliases. @file{configure} calls the Bourne shell script
8e04817f
AC
35900@code{config.sub} to map abbreviations to full names; you can read the
35901script, if you wish, or you can use it to test your guesses on
35902abbreviations---for example:
c906108c 35903
8e04817f
AC
35904@smallexample
35905% sh config.sub i386-linux
35906i386-pc-linux-gnu
35907% sh config.sub alpha-linux
35908alpha-unknown-linux-gnu
35909% sh config.sub hp9k700
35910hppa1.1-hp-hpux
35911% sh config.sub sun4
35912sparc-sun-sunos4.1.1
35913% sh config.sub sun3
35914m68k-sun-sunos4.1.1
35915% sh config.sub i986v
35916Invalid configuration `i986v': machine `i986v' not recognized
35917@end smallexample
c906108c 35918
8e04817f
AC
35919@noindent
35920@code{config.sub} is also distributed in the @value{GDBN} source
35921directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}).
d700128c 35922
8e04817f 35923@node Configure Options
db2e3e2e 35924@section @file{configure} Options
c906108c 35925
db2e3e2e 35926Here is a summary of the @file{configure} options and arguments that
7f0bd420
TT
35927are most often useful for building @value{GDBN}. @file{configure}
35928also has several other options not listed here. @inforef{Running
35929configure scripts,,autoconf.info}, for a full
35930explanation of @file{configure}.
c906108c 35931
474c8240 35932@smallexample
8e04817f
AC
35933configure @r{[}--help@r{]}
35934 @r{[}--prefix=@var{dir}@r{]}
35935 @r{[}--exec-prefix=@var{dir}@r{]}
35936 @r{[}--srcdir=@var{dirname}@r{]}
8e04817f 35937 @r{[}--target=@var{target}@r{]}
474c8240 35938@end smallexample
c906108c 35939
8e04817f
AC
35940@noindent
35941You may introduce options with a single @samp{-} rather than
35942@samp{--} if you prefer; but you may abbreviate option names if you use
35943@samp{--}.
c906108c 35944
8e04817f
AC
35945@table @code
35946@item --help
db2e3e2e 35947Display a quick summary of how to invoke @file{configure}.
c906108c 35948
8e04817f
AC
35949@item --prefix=@var{dir}
35950Configure the source to install programs and files under directory
35951@file{@var{dir}}.
c906108c 35952
8e04817f
AC
35953@item --exec-prefix=@var{dir}
35954Configure the source to install programs under directory
35955@file{@var{dir}}.
c906108c 35956
8e04817f
AC
35957@c avoid splitting the warning from the explanation:
35958@need 2000
35959@item --srcdir=@var{dirname}
8e04817f
AC
35960Use this option to make configurations in directories separate from the
35961@value{GDBN} source directories. Among other things, you can use this to
35962build (or maintain) several configurations simultaneously, in separate
db2e3e2e 35963directories. @file{configure} writes configuration-specific files in
8e04817f 35964the current directory, but arranges for them to use the source in the
db2e3e2e 35965directory @var{dirname}. @file{configure} creates directories under
8e04817f
AC
35966the working directory in parallel to the source directories below
35967@var{dirname}.
c906108c 35968
8e04817f
AC
35969@item --target=@var{target}
35970Configure @value{GDBN} for cross-debugging programs running on the specified
35971@var{target}. Without this option, @value{GDBN} is configured to debug
35972programs that run on the same machine (@var{host}) as @value{GDBN} itself.
c906108c 35973
a95746f9
TT
35974There is no convenient way to generate a list of all available
35975targets. Also see the @code{--enable-targets} option, below.
8e04817f 35976@end table
c906108c 35977
a95746f9
TT
35978There are many other options that are specific to @value{GDBN}. This
35979lists just the most common ones; there are some very specialized
35980options not described here.
35981
35982@table @code
35983@item --enable-targets=@r{[}@var{target}@r{]}@dots{}
35984@itemx --enable-targets=all
35985Configure @value{GDBN} for cross-debugging programs running on the
35986specified list of targets. The special value @samp{all} configures
35987@value{GDBN} for debugging programs running on any target it supports.
35988
35989@item --with-gdb-datadir=@var{path}
35990Set the @value{GDBN}-specific data directory. @value{GDBN} will look
35991here for certain supporting files or scripts. This defaults to the
35992@file{gdb} subdirectory of @samp{datadi} (which can be set using
35993@code{--datadir}).
35994
35995@item --with-relocated-sources=@var{dir}
35996Sets up the default source path substitution rule so that directory
35997names recorded in debug information will be automatically adjusted for
35998any directory under @var{dir}. @var{dir} should be a subdirectory of
35999@value{GDBN}'s configured prefix, the one mentioned in the
36000@code{--prefix} or @code{--exec-prefix} options to configure. This
36001option is useful if GDB is supposed to be moved to a different place
36002after it is built.
36003
36004@item --enable-64-bit-bfd
36005Enable 64-bit support in BFD on 32-bit hosts.
36006
36007@item --disable-gdbmi
36008Build @value{GDBN} without the GDB/MI machine interface
36009(@pxref{GDB/MI}).
36010
36011@item --enable-tui
36012Build @value{GDBN} with the text-mode full-screen user interface
36013(TUI). Requires a curses library (ncurses and cursesX are also
36014supported).
36015
36016@item --with-curses
36017Use the curses library instead of the termcap library, for text-mode
36018terminal operations.
36019
36020@item --with-libunwind-ia64
36021Use the libunwind library for unwinding function call stack on ia64
36022target platforms. See http://www.nongnu.org/libunwind/index.html for
36023details.
36024
36025@item --with-system-readline
36026Use the readline library installed on the host, rather than the
36027library supplied as part of @value{GDBN}.
36028
36029@item --with-system-zlib
36030Use the zlib library installed on the host, rather than the library
36031supplied as part of @value{GDBN}.
36032
36033@item --with-expat
36034Build @value{GDBN} with Expat, a library for XML parsing. (Done by
36035default if libexpat is installed and found at configure time.) This
36036library is used to read XML files supplied with @value{GDBN}. If it
36037is unavailable, some features, such as remote protocol memory maps,
36038target descriptions, and shared library lists, that are based on XML
36039files, will not be available in @value{GDBN}. If your host does not
36040have libexpat installed, you can get the latest version from
36041`http://expat.sourceforge.net'.
36042
36043@item --with-libiconv-prefix@r{[}=@var{dir}@r{]}
36044
36045Build @value{GDBN} with GNU libiconv, a character set encoding
36046conversion library. This is not done by default, as on GNU systems
36047the @code{iconv} that is built in to the C library is sufficient. If
36048your host does not have a working @code{iconv}, you can get the latest
36049version of GNU iconv from `https://www.gnu.org/software/libiconv/'.
36050
36051@value{GDBN}'s build system also supports building GNU libiconv as
36052part of the overall build. @xref{Requirements}.
36053
36054@item --with-lzma
36055Build @value{GDBN} with LZMA, a compression library. (Done by default
36056if liblzma is installed and found at configure time.) LZMA is used by
36057@value{GDBN}'s "mini debuginfo" feature, which is only useful on
36058platforms using the ELF object file format. If your host does not
36059have liblzma installed, you can get the latest version from
36060`https://tukaani.org/xz/'.
36061
36062@item --with-mpfr
36063Build @value{GDBN} with GNU MPFR, a library for multiple-precision
36064floating-point computation with correct rounding. (Done by default if
36065GNU MPFR is installed and found at configure time.) This library is
36066used to emulate target floating-point arithmetic during expression
36067evaluation when the target uses different floating-point formats than
36068the host. If GNU MPFR is not available, @value{GDBN} will fall back
36069to using host floating-point arithmetic. If your host does not have
36070GNU MPFR installed, you can get the latest version from
36071`http://www.mpfr.org'.
36072
36073@item --with-python@r{[}=@var{python}@r{]}
36074Build @value{GDBN} with Python scripting support. (Done by default if
36075libpython is present and found at configure time.) Python makes
36076@value{GDBN} scripting much more powerful than the restricted CLI
36077scripting language. If your host does not have Python installed, you
36078can find it on `http://www.python.org/download/'. The oldest version
2c3fc25d 36079of Python supported by GDB is 2.6. The optional argument @var{python}
a95746f9
TT
36080is used to find the Python headers and libraries. It can be either
36081the name of a Python executable, or the name of the directory in which
36082Python is installed.
36083
36084@item --with-guile[=GUILE]'
36085Build @value{GDBN} with GNU Guile scripting support. (Done by default
36086if libguile is present and found at configure time.) If your host
36087does not have Guile installed, you can find it at
36088`https://www.gnu.org/software/guile/'. The optional argument GUILE
36089can be a version number, which will cause @code{configure} to try to
36090use that version of Guile; or the file name of a @code{pkg-config}
36091executable, which will be queried to find the information needed to
36092compile and link against Guile.
36093
36094@item --without-included-regex
36095Don't use the regex library included with @value{GDBN} (as part of the
36096libiberty library). This is the default on hosts with version 2 of
36097the GNU C library.
36098
36099@item --with-sysroot=@var{dir}
36100Use @var{dir} as the default system root directory for libraries whose
36101file names begin with @file{/lib}' or @file{/usr/lib'}. (The value of
36102@var{dir} can be modified at run time by using the @command{set
36103sysroot} command.) If @var{dir} is under the @value{GDBN} configured
36104prefix (set with @code{--prefix} or @code{--exec-prefix options}, the
36105default system root will be automatically adjusted if and when
36106@value{GDBN} is moved to a different location.
36107
36108@item --with-system-gdbinit=@var{file}
36109Configure @value{GDBN} to automatically load a system-wide init file.
36110@var{file} should be an absolute file name. If @var{file} is in a
36111directory under the configured prefix, and @value{GDBN} is moved to
36112another location after being built, the location of the system-wide
36113init file will be adjusted accordingly.
36114
36115@item --enable-build-warnings
36116When building the @value{GDBN} sources, ask the compiler to warn about
36117any code which looks even vaguely suspicious. It passes many
36118different warning flags, depending on the exact version of the
36119compiler you are using.
36120
36121@item --enable-werror
36122Treat compiler warnings as werrors. It adds the @code{-Werror} flag
36123to the compiler, which will fail the compilation if the compiler
36124outputs any warning messages.
f35d5ade
TT
36125
36126@item --enable-ubsan
eff98030
TT
36127Enable the GCC undefined behavior sanitizer. This is disabled by
36128default, but passing @code{--enable-ubsan=yes} or
36129@code{--enable-ubsan=auto} to @code{configure} will enable it. The
36130undefined behavior sanitizer checks for C@t{++} undefined behavior.
36131It has a performance cost, so if you are looking at @value{GDBN}'s
36132performance, you should disable it. The undefined behavior sanitizer
36133was first introduced in GCC 4.9.
a95746f9 36134@end table
c906108c 36135
098b41a6
JG
36136@node System-wide configuration
36137@section System-wide configuration and settings
36138@cindex system-wide init file
36139
36140@value{GDBN} can be configured to have a system-wide init file;
36141this file will be read and executed at startup (@pxref{Startup, , What
36142@value{GDBN} does during startup}).
36143
36144Here is the corresponding configure option:
36145
36146@table @code
36147@item --with-system-gdbinit=@var{file}
36148Specify that the default location of the system-wide init file is
36149@var{file}.
36150@end table
36151
36152If @value{GDBN} has been configured with the option @option{--prefix=$prefix},
36153it may be subject to relocation. Two possible cases:
36154
36155@itemize @bullet
36156@item
36157If the default location of this init file contains @file{$prefix},
36158it will be subject to relocation. Suppose that the configure options
36159are @option{--prefix=$prefix --with-system-gdbinit=$prefix/etc/gdbinit};
36160if @value{GDBN} is moved from @file{$prefix} to @file{$install}, the system
36161init file is looked for as @file{$install/etc/gdbinit} instead of
36162@file{$prefix/etc/gdbinit}.
36163
36164@item
36165By contrast, if the default location does not contain the prefix,
36166it will not be relocated. E.g.@: if @value{GDBN} has been configured with
36167@option{--prefix=/usr/local --with-system-gdbinit=/usr/share/gdb/gdbinit},
36168then @value{GDBN} will always look for @file{/usr/share/gdb/gdbinit},
36169wherever @value{GDBN} is installed.
36170@end itemize
36171
e64e0392
DE
36172If the configured location of the system-wide init file (as given by the
36173@option{--with-system-gdbinit} option at configure time) is in the
36174data-directory (as specified by @option{--with-gdb-datadir} at configure
36175time) or in one of its subdirectories, then @value{GDBN} will look for the
36176system-wide init file in the directory specified by the
36177@option{--data-directory} command-line option.
36178Note that the system-wide init file is only read once, during @value{GDBN}
36179initialization. If the data-directory is changed after @value{GDBN} has
36180started with the @code{set data-directory} command, the file will not be
36181reread.
36182
5901af59
JB
36183@menu
36184* System-wide Configuration Scripts:: Installed System-wide Configuration Scripts
36185@end menu
36186
36187@node System-wide Configuration Scripts
0201faac
JB
36188@subsection Installed System-wide Configuration Scripts
36189@cindex system-wide configuration scripts
36190
36191The @file{system-gdbinit} directory, located inside the data-directory
36192(as specified by @option{--with-gdb-datadir} at configure time) contains
36193a number of scripts which can be used as system-wide init files. To
36194automatically source those scripts at startup, @value{GDBN} should be
36195configured with @option{--with-system-gdbinit}. Otherwise, any user
36196should be able to source them by hand as needed.
36197
36198The following scripts are currently available:
36199@itemize @bullet
36200
36201@item @file{elinos.py}
36202@pindex elinos.py
36203@cindex ELinOS system-wide configuration script
36204This script is useful when debugging a program on an ELinOS target.
36205It takes advantage of the environment variables defined in a standard
36206ELinOS environment in order to determine the location of the system
36207shared libraries, and then sets the @samp{solib-absolute-prefix}
36208and @samp{solib-search-path} variables appropriately.
36209
36210@item @file{wrs-linux.py}
36211@pindex wrs-linux.py
36212@cindex Wind River Linux system-wide configuration script
36213This script is useful when debugging a program on a target running
36214Wind River Linux. It expects the @env{ENV_PREFIX} to be set to
36215the host-side sysroot used by the target system.
36216
36217@end itemize
36218
8e04817f
AC
36219@node Maintenance Commands
36220@appendix Maintenance Commands
36221@cindex maintenance commands
36222@cindex internal commands
c906108c 36223
8e04817f 36224In addition to commands intended for @value{GDBN} users, @value{GDBN}
09d4efe1
EZ
36225includes a number of commands intended for @value{GDBN} developers,
36226that are not documented elsewhere in this manual. These commands are
da316a69
EZ
36227provided here for reference. (For commands that turn on debugging
36228messages, see @ref{Debugging Output}.)
c906108c 36229
8e04817f 36230@table @code
09d4efe1 36231@kindex maint agent
782b2b07 36232@kindex maint agent-eval
f77cc5f0
HZ
36233@item maint agent @r{[}-at @var{location}@r{,}@r{]} @var{expression}
36234@itemx maint agent-eval @r{[}-at @var{location}@r{,}@r{]} @var{expression}
09d4efe1
EZ
36235Translate the given @var{expression} into remote agent bytecodes.
36236This command is useful for debugging the Agent Expression mechanism
782b2b07
SS
36237(@pxref{Agent Expressions}). The @samp{agent} version produces an
36238expression useful for data collection, such as by tracepoints, while
36239@samp{maint agent-eval} produces an expression that evaluates directly
36240to a result. For instance, a collection expression for @code{globa +
36241globb} will include bytecodes to record four bytes of memory at each
36242of the addresses of @code{globa} and @code{globb}, while discarding
36243the result of the addition, while an evaluation expression will do the
36244addition and return the sum.
f77cc5f0
HZ
36245If @code{-at} is given, generate remote agent bytecode for @var{location}.
36246If not, generate remote agent bytecode for current frame PC address.
09d4efe1 36247
d3ce09f5
SS
36248@kindex maint agent-printf
36249@item maint agent-printf @var{format},@var{expr},...
36250Translate the given format string and list of argument expressions
36251into remote agent bytecodes and display them as a disassembled list.
36252This command is useful for debugging the agent version of dynamic
6dd24dfa 36253printf (@pxref{Dynamic Printf}).
d3ce09f5 36254
8e04817f
AC
36255@kindex maint info breakpoints
36256@item @anchor{maint info breakpoints}maint info breakpoints
36257Using the same format as @samp{info breakpoints}, display both the
36258breakpoints you've set explicitly, and those @value{GDBN} is using for
36259internal purposes. Internal breakpoints are shown with negative
36260breakpoint numbers. The type column identifies what kind of breakpoint
36261is shown:
c906108c 36262
8e04817f
AC
36263@table @code
36264@item breakpoint
36265Normal, explicitly set breakpoint.
c906108c 36266
8e04817f
AC
36267@item watchpoint
36268Normal, explicitly set watchpoint.
c906108c 36269
8e04817f
AC
36270@item longjmp
36271Internal breakpoint, used to handle correctly stepping through
36272@code{longjmp} calls.
c906108c 36273
8e04817f
AC
36274@item longjmp resume
36275Internal breakpoint at the target of a @code{longjmp}.
c906108c 36276
8e04817f
AC
36277@item until
36278Temporary internal breakpoint used by the @value{GDBN} @code{until} command.
c906108c 36279
8e04817f
AC
36280@item finish
36281Temporary internal breakpoint used by the @value{GDBN} @code{finish} command.
c906108c 36282
8e04817f
AC
36283@item shlib events
36284Shared library events.
c906108c 36285
8e04817f 36286@end table
c906108c 36287
b0627500
MM
36288@kindex maint info btrace
36289@item maint info btrace
36290Pint information about raw branch tracing data.
36291
36292@kindex maint btrace packet-history
36293@item maint btrace packet-history
36294Print the raw branch trace packets that are used to compute the
36295execution history for the @samp{record btrace} command. Both the
36296information and the format in which it is printed depend on the btrace
36297recording format.
36298
36299@table @code
36300@item bts
36301For the BTS recording format, print a list of blocks of sequential
36302code. For each block, the following information is printed:
36303
36304@table @asis
36305@item Block number
36306Newer blocks have higher numbers. The oldest block has number zero.
36307@item Lowest @samp{PC}
36308@item Highest @samp{PC}
36309@end table
36310
36311@item pt
bc504a31
PA
36312For the Intel Processor Trace recording format, print a list of
36313Intel Processor Trace packets. For each packet, the following
b0627500
MM
36314information is printed:
36315
36316@table @asis
36317@item Packet number
36318Newer packets have higher numbers. The oldest packet has number zero.
36319@item Trace offset
36320The packet's offset in the trace stream.
36321@item Packet opcode and payload
36322@end table
36323@end table
36324
36325@kindex maint btrace clear-packet-history
36326@item maint btrace clear-packet-history
36327Discards the cached packet history printed by the @samp{maint btrace
36328packet-history} command. The history will be computed again when
36329needed.
36330
36331@kindex maint btrace clear
36332@item maint btrace clear
36333Discard the branch trace data. The data will be fetched anew and the
36334branch trace will be recomputed when needed.
36335
36336This implicitly truncates the branch trace to a single branch trace
36337buffer. When updating branch trace incrementally, the branch trace
36338available to @value{GDBN} may be bigger than a single branch trace
36339buffer.
36340
36341@kindex maint set btrace pt skip-pad
36342@item maint set btrace pt skip-pad
36343@kindex maint show btrace pt skip-pad
36344@item maint show btrace pt skip-pad
36345Control whether @value{GDBN} will skip PAD packets when computing the
36346packet history.
36347
fff08868
HZ
36348@kindex set displaced-stepping
36349@kindex show displaced-stepping
237fc4c9
PA
36350@cindex displaced stepping support
36351@cindex out-of-line single-stepping
fff08868
HZ
36352@item set displaced-stepping
36353@itemx show displaced-stepping
237fc4c9 36354Control whether or not @value{GDBN} will do @dfn{displaced stepping}
fff08868
HZ
36355if the target supports it. Displaced stepping is a way to single-step
36356over breakpoints without removing them from the inferior, by executing
36357an out-of-line copy of the instruction that was originally at the
36358breakpoint location. It is also known as out-of-line single-stepping.
36359
36360@table @code
36361@item set displaced-stepping on
36362If the target architecture supports it, @value{GDBN} will use
36363displaced stepping to step over breakpoints.
36364
36365@item set displaced-stepping off
36366@value{GDBN} will not use displaced stepping to step over breakpoints,
36367even if such is supported by the target architecture.
36368
36369@cindex non-stop mode, and @samp{set displaced-stepping}
36370@item set displaced-stepping auto
36371This is the default mode. @value{GDBN} will use displaced stepping
36372only if non-stop mode is active (@pxref{Non-Stop Mode}) and the target
36373architecture supports displaced stepping.
36374@end table
237fc4c9 36375
7d0c9981
DE
36376@kindex maint check-psymtabs
36377@item maint check-psymtabs
36378Check the consistency of currently expanded psymtabs versus symtabs.
36379Use this to check, for example, whether a symbol is in one but not the other.
36380
09d4efe1
EZ
36381@kindex maint check-symtabs
36382@item maint check-symtabs
7d0c9981
DE
36383Check the consistency of currently expanded symtabs.
36384
36385@kindex maint expand-symtabs
36386@item maint expand-symtabs [@var{regexp}]
36387Expand symbol tables.
36388If @var{regexp} is specified, only expand symbol tables for file
36389names matching @var{regexp}.
09d4efe1 36390
992c7d70
GB
36391@kindex maint set catch-demangler-crashes
36392@kindex maint show catch-demangler-crashes
36393@cindex demangler crashes
36394@item maint set catch-demangler-crashes [on|off]
36395@itemx maint show catch-demangler-crashes
36396Control whether @value{GDBN} should attempt to catch crashes in the
36397symbol name demangler. The default is to attempt to catch crashes.
36398If enabled, the first time a crash is caught, a core file is created,
36399the offending symbol is displayed and the user is presented with the
36400option to terminate the current session.
36401
09d4efe1
EZ
36402@kindex maint cplus first_component
36403@item maint cplus first_component @var{name}
36404Print the first C@t{++} class/namespace component of @var{name}.
36405
36406@kindex maint cplus namespace
36407@item maint cplus namespace
36408Print the list of possible C@t{++} namespaces.
36409
09d4efe1
EZ
36410@kindex maint deprecate
36411@kindex maint undeprecate
36412@cindex deprecated commands
36413@item maint deprecate @var{command} @r{[}@var{replacement}@r{]}
36414@itemx maint undeprecate @var{command}
36415Deprecate or undeprecate the named @var{command}. Deprecated commands
36416cause @value{GDBN} to issue a warning when you use them. The optional
36417argument @var{replacement} says which newer command should be used in
36418favor of the deprecated one; if it is given, @value{GDBN} will mention
36419the replacement as part of the warning.
36420
36421@kindex maint dump-me
36422@item maint dump-me
721c2651 36423@cindex @code{SIGQUIT} signal, dump core of @value{GDBN}
09d4efe1 36424Cause a fatal signal in the debugger and force it to dump its core.
721c2651
EZ
36425This is supported only on systems which support aborting a program
36426with the @code{SIGQUIT} signal.
09d4efe1 36427
8d30a00d
AC
36428@kindex maint internal-error
36429@kindex maint internal-warning
57fcfb1b
GB
36430@kindex maint demangler-warning
36431@cindex demangler crashes
09d4efe1
EZ
36432@item maint internal-error @r{[}@var{message-text}@r{]}
36433@itemx maint internal-warning @r{[}@var{message-text}@r{]}
57fcfb1b
GB
36434@itemx maint demangler-warning @r{[}@var{message-text}@r{]}
36435
36436Cause @value{GDBN} to call the internal function @code{internal_error},
36437@code{internal_warning} or @code{demangler_warning} and hence behave
7ee67ee4 36438as though an internal problem has been detected. In addition to
57fcfb1b
GB
36439reporting the internal problem, these functions give the user the
36440opportunity to either quit @value{GDBN} or (for @code{internal_error}
36441and @code{internal_warning}) create a core file of the current
8d30a00d
AC
36442@value{GDBN} session.
36443
09d4efe1
EZ
36444These commands take an optional parameter @var{message-text} that is
36445used as the text of the error or warning message.
36446
d3e8051b 36447Here's an example of using @code{internal-error}:
09d4efe1 36448
8d30a00d 36449@smallexample
f7dc1244 36450(@value{GDBP}) @kbd{maint internal-error testing, 1, 2}
8d30a00d
AC
36451@dots{}/maint.c:121: internal-error: testing, 1, 2
36452A problem internal to GDB has been detected. Further
36453debugging may prove unreliable.
36454Quit this debugging session? (y or n) @kbd{n}
36455Create a core file? (y or n) @kbd{n}
f7dc1244 36456(@value{GDBP})
8d30a00d
AC
36457@end smallexample
36458
3c16cced
PA
36459@cindex @value{GDBN} internal error
36460@cindex internal errors, control of @value{GDBN} behavior
57fcfb1b 36461@cindex demangler crashes
3c16cced
PA
36462
36463@kindex maint set internal-error
36464@kindex maint show internal-error
36465@kindex maint set internal-warning
36466@kindex maint show internal-warning
57fcfb1b
GB
36467@kindex maint set demangler-warning
36468@kindex maint show demangler-warning
3c16cced
PA
36469@item maint set internal-error @var{action} [ask|yes|no]
36470@itemx maint show internal-error @var{action}
36471@itemx maint set internal-warning @var{action} [ask|yes|no]
36472@itemx maint show internal-warning @var{action}
57fcfb1b
GB
36473@itemx maint set demangler-warning @var{action} [ask|yes|no]
36474@itemx maint show demangler-warning @var{action}
3c16cced
PA
36475When @value{GDBN} reports an internal problem (error or warning) it
36476gives the user the opportunity to both quit @value{GDBN} and create a
36477core file of the current @value{GDBN} session. These commands let you
36478override the default behaviour for each particular @var{action},
36479described in the table below.
36480
36481@table @samp
36482@item quit
36483You can specify that @value{GDBN} should always (yes) or never (no)
36484quit. The default is to ask the user what to do.
36485
36486@item corefile
36487You can specify that @value{GDBN} should always (yes) or never (no)
57fcfb1b
GB
36488create a core file. The default is to ask the user what to do. Note
36489that there is no @code{corefile} option for @code{demangler-warning}:
36490demangler warnings always create a core file and this cannot be
36491disabled.
3c16cced
PA
36492@end table
36493
09d4efe1
EZ
36494@kindex maint packet
36495@item maint packet @var{text}
36496If @value{GDBN} is talking to an inferior via the serial protocol,
36497then this command sends the string @var{text} to the inferior, and
36498displays the response packet. @value{GDBN} supplies the initial
36499@samp{$} character, the terminating @samp{#} character, and the
36500checksum.
36501
36502@kindex maint print architecture
36503@item maint print architecture @r{[}@var{file}@r{]}
36504Print the entire architecture configuration. The optional argument
36505@var{file} names the file where the output goes.
8d30a00d 36506
8e2141c6 36507@kindex maint print c-tdesc @r{[}@var{file}@r{]}
81adfced 36508@item maint print c-tdesc
8e2141c6
YQ
36509Print the target description (@pxref{Target Descriptions}) as
36510a C source file. By default, the target description is for the current
36511target, but if the optional argument @var{file} is provided, that file
36512is used to produce the description. The @var{file} should be an XML
36513document, of the form described in @ref{Target Description Format}.
36514The created source file is built into @value{GDBN} when @value{GDBN} is
36515built again. This command is used by developers after they add or
36516modify XML target descriptions.
81adfced 36517
27d41eac
YQ
36518@kindex maint check xml-descriptions
36519@item maint check xml-descriptions @var{dir}
36520Check that the target descriptions dynamically created by @value{GDBN}
36521equal the descriptions created from XML files found in @var{dir}.
36522
41fc26a2 36523@anchor{maint check libthread-db}
5045b3d7
GB
36524@kindex maint check libthread-db
36525@item maint check libthread-db
36526Run integrity checks on the current inferior's thread debugging
36527library. This exercises all @code{libthread_db} functionality used by
36528@value{GDBN} on GNU/Linux systems, and by extension also exercises the
36529@code{proc_service} functions provided by @value{GDBN} that
36530@code{libthread_db} uses. Note that parts of the test may be skipped
36531on some platforms when debugging core files.
36532
00905d52
AC
36533@kindex maint print dummy-frames
36534@item maint print dummy-frames
00905d52
AC
36535Prints the contents of @value{GDBN}'s internal dummy-frame stack.
36536
36537@smallexample
f7dc1244 36538(@value{GDBP}) @kbd{b add}
00905d52 36539@dots{}
f7dc1244 36540(@value{GDBP}) @kbd{print add(2,3)}
00905d52
AC
36541Breakpoint 2, add (a=2, b=3) at @dots{}
3654258 return (a + b);
36543The program being debugged stopped while in a function called from GDB.
36544@dots{}
f7dc1244 36545(@value{GDBP}) @kbd{maint print dummy-frames}
b67a2c6f 365460xa8206d8: id=@{stack=0xbfffe734,code=0xbfffe73f,!special@}, ptid=process 9353
f7dc1244 36547(@value{GDBP})
00905d52
AC
36548@end smallexample
36549
36550Takes an optional file parameter.
36551
0680b120
AC
36552@kindex maint print registers
36553@kindex maint print raw-registers
36554@kindex maint print cooked-registers
617073a9 36555@kindex maint print register-groups
c21236dc 36556@kindex maint print remote-registers
09d4efe1
EZ
36557@item maint print registers @r{[}@var{file}@r{]}
36558@itemx maint print raw-registers @r{[}@var{file}@r{]}
36559@itemx maint print cooked-registers @r{[}@var{file}@r{]}
36560@itemx maint print register-groups @r{[}@var{file}@r{]}
c21236dc 36561@itemx maint print remote-registers @r{[}@var{file}@r{]}
0680b120
AC
36562Print @value{GDBN}'s internal register data structures.
36563
617073a9 36564The command @code{maint print raw-registers} includes the contents of
c21236dc
PA
36565the raw register cache; the command @code{maint print
36566cooked-registers} includes the (cooked) value of all registers,
36567including registers which aren't available on the target nor visible
36568to user; the command @code{maint print register-groups} includes the
36569groups that each register is a member of; and the command @code{maint
36570print remote-registers} includes the remote target's register numbers
0a7cfe2c 36571and offsets in the `G' packets.
0680b120 36572
09d4efe1
EZ
36573These commands take an optional parameter, a file name to which to
36574write the information.
0680b120 36575
617073a9 36576@kindex maint print reggroups
09d4efe1
EZ
36577@item maint print reggroups @r{[}@var{file}@r{]}
36578Print @value{GDBN}'s internal register group data structures. The
36579optional argument @var{file} tells to what file to write the
36580information.
617073a9 36581
09d4efe1 36582The register groups info looks like this:
617073a9
AC
36583
36584@smallexample
f7dc1244 36585(@value{GDBP}) @kbd{maint print reggroups}
b383017d
RM
36586 Group Type
36587 general user
36588 float user
36589 all user
36590 vector user
36591 system user
36592 save internal
36593 restore internal
617073a9
AC
36594@end smallexample
36595
09d4efe1
EZ
36596@kindex flushregs
36597@item flushregs
36598This command forces @value{GDBN} to flush its internal register cache.
36599
36600@kindex maint print objfiles
36601@cindex info for known object files
52e260a3
DE
36602@item maint print objfiles @r{[}@var{regexp}@r{]}
36603Print a dump of all known object files.
36604If @var{regexp} is specified, only print object files whose names
36605match @var{regexp}. For each object file, this command prints its name,
36606address in memory, and all of its psymtabs and symtabs.
09d4efe1 36607
f5b95c01
AA
36608@kindex maint print user-registers
36609@cindex user registers
36610@item maint print user-registers
36611List all currently available @dfn{user registers}. User registers
36612typically provide alternate names for actual hardware registers. They
36613include the four ``standard'' registers @code{$fp}, @code{$pc},
36614@code{$sp}, and @code{$ps}. @xref{standard registers}. User
36615registers can be used in expressions in the same way as the canonical
36616register names, but only the latter are listed by the @code{info
36617registers} and @code{maint print registers} commands.
36618
8a1ea21f
DE
36619@kindex maint print section-scripts
36620@cindex info for known .debug_gdb_scripts-loaded scripts
36621@item maint print section-scripts [@var{regexp}]
36622Print a dump of scripts specified in the @code{.debug_gdb_section} section.
36623If @var{regexp} is specified, only print scripts loaded by object files
36624matching @var{regexp}.
36625For each script, this command prints its name as specified in the objfile,
36626and the full path if known.
8e0583c8 36627@xref{dotdebug_gdb_scripts section}.
8a1ea21f 36628
09d4efe1
EZ
36629@kindex maint print statistics
36630@cindex bcache statistics
36631@item maint print statistics
36632This command prints, for each object file in the program, various data
36633about that object file followed by the byte cache (@dfn{bcache})
36634statistics for the object file. The objfile data includes the number
d3e8051b 36635of minimal, partial, full, and stabs symbols, the number of types
09d4efe1
EZ
36636defined by the objfile, the number of as yet unexpanded psym tables,
36637the number of line tables and string tables, and the amount of memory
36638used by the various tables. The bcache statistics include the counts,
36639sizes, and counts of duplicates of all and unique objects, max,
36640average, and median entry size, total memory used and its overhead and
36641savings, and various measures of the hash table size and chain
36642lengths.
36643
c7ba131e
JB
36644@kindex maint print target-stack
36645@cindex target stack description
36646@item maint print target-stack
36647A @dfn{target} is an interface between the debugger and a particular
36648kind of file or process. Targets can be stacked in @dfn{strata},
36649so that more than one target can potentially respond to a request.
36650In particular, memory accesses will walk down the stack of targets
36651until they find a target that is interested in handling that particular
36652address.
36653
36654This command prints a short description of each layer that was pushed on
36655the @dfn{target stack}, starting from the top layer down to the bottom one.
36656
09d4efe1
EZ
36657@kindex maint print type
36658@cindex type chain of a data type
36659@item maint print type @var{expr}
36660Print the type chain for a type specified by @var{expr}. The argument
36661can be either a type name or a symbol. If it is a symbol, the type of
36662that symbol is described. The type chain produced by this command is
36663a recursive definition of the data type as stored in @value{GDBN}'s
36664data structures, including its flags and contained types.
36665
dcd1f979
TT
36666@kindex maint selftest
36667@cindex self tests
1526853e 36668@item maint selftest @r{[}@var{filter}@r{]}
dcd1f979
TT
36669Run any self tests that were compiled in to @value{GDBN}. This will
36670print a message showing how many tests were run, and how many failed.
1526853e
SM
36671If a @var{filter} is passed, only the tests with @var{filter} in their
36672name will by ran.
36673
36674@kindex "maint info selftests"
36675@cindex self tests
36676@item maint info selftests
36677List the selftests compiled in to @value{GDBN}.
dcd1f979 36678
b4f54984
DE
36679@kindex maint set dwarf always-disassemble
36680@kindex maint show dwarf always-disassemble
36681@item maint set dwarf always-disassemble
36682@item maint show dwarf always-disassemble
9eae7c52
TT
36683Control the behavior of @code{info address} when using DWARF debugging
36684information.
36685
36686The default is @code{off}, which means that @value{GDBN} should try to
36687describe a variable's location in an easily readable format. When
36688@code{on}, @value{GDBN} will instead display the DWARF location
36689expression in an assembly-like format. Note that some locations are
36690too complex for @value{GDBN} to describe simply; in this case you will
36691always see the disassembly form.
36692
36693Here is an example of the resulting disassembly:
36694
36695@smallexample
36696(gdb) info addr argc
36697Symbol "argc" is a complex DWARF expression:
36698 1: DW_OP_fbreg 0
36699@end smallexample
36700
36701For more information on these expressions, see
36702@uref{http://www.dwarfstd.org/, the DWARF standard}.
36703
b4f54984
DE
36704@kindex maint set dwarf max-cache-age
36705@kindex maint show dwarf max-cache-age
36706@item maint set dwarf max-cache-age
36707@itemx maint show dwarf max-cache-age
36708Control the DWARF compilation unit cache.
09d4efe1 36709
b4f54984 36710@cindex DWARF compilation units cache
09d4efe1 36711In object files with inter-compilation-unit references, such as those
b4f54984 36712produced by the GCC option @samp{-feliminate-dwarf2-dups}, the DWARF
09d4efe1
EZ
36713reader needs to frequently refer to previously read compilation units.
36714This setting controls how long a compilation unit will remain in the
36715cache if it is not referenced. A higher limit means that cached
36716compilation units will be stored in memory longer, and more total
36717memory will be used. Setting it to zero disables caching, which will
36718slow down @value{GDBN} startup, but reduce memory consumption.
36719
3c3bb058
AB
36720@kindex maint set dwarf unwinders
36721@kindex maint show dwarf unwinders
36722@item maint set dwarf unwinders
36723@itemx maint show dwarf unwinders
36724Control use of the DWARF frame unwinders.
36725
36726@cindex DWARF frame unwinders
36727Many targets that support DWARF debugging use @value{GDBN}'s DWARF
36728frame unwinders to build the backtrace. Many of these targets will
36729also have a second mechanism for building the backtrace for use in
36730cases where DWARF information is not available, this second mechanism
36731is often an analysis of a function's prologue.
36732
36733In order to extend testing coverage of the second level stack
36734unwinding mechanisms it is helpful to be able to disable the DWARF
36735stack unwinders, this can be done with this switch.
36736
36737In normal use of @value{GDBN} disabling the DWARF unwinders is not
36738advisable, there are cases that are better handled through DWARF than
36739prologue analysis, and the debug experience is likely to be better
36740with the DWARF frame unwinders enabled.
36741
36742If DWARF frame unwinders are not supported for a particular target
36743architecture, then enabling this flag does not cause them to be used.
e7ba9c65
DJ
36744@kindex maint set profile
36745@kindex maint show profile
36746@cindex profiling GDB
36747@item maint set profile
36748@itemx maint show profile
36749Control profiling of @value{GDBN}.
36750
36751Profiling will be disabled until you use the @samp{maint set profile}
36752command to enable it. When you enable profiling, the system will begin
36753collecting timing and execution count data; when you disable profiling or
36754exit @value{GDBN}, the results will be written to a log file. Remember that
36755if you use profiling, @value{GDBN} will overwrite the profiling log file
36756(often called @file{gmon.out}). If you have a record of important profiling
36757data in a @file{gmon.out} file, be sure to move it to a safe location.
36758
36759Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be
b383017d 36760compiled with the @samp{-pg} compiler option.
e7ba9c65 36761
cbe54154
PA
36762@kindex maint set show-debug-regs
36763@kindex maint show show-debug-regs
eac35c4e 36764@cindex hardware debug registers
cbe54154
PA
36765@item maint set show-debug-regs
36766@itemx maint show show-debug-regs
eac35c4e 36767Control whether to show variables that mirror the hardware debug
6dd315ba 36768registers. Use @code{on} to enable, @code{off} to disable. If
3f94c067 36769enabled, the debug registers values are shown when @value{GDBN} inserts or
09d4efe1
EZ
36770removes a hardware breakpoint or watchpoint, and when the inferior
36771triggers a hardware-assisted breakpoint or watchpoint.
36772
711e434b
PM
36773@kindex maint set show-all-tib
36774@kindex maint show show-all-tib
36775@item maint set show-all-tib
36776@itemx maint show show-all-tib
36777Control whether to show all non zero areas within a 1k block starting
36778at thread local base, when using the @samp{info w32 thread-information-block}
36779command.
36780
329ea579
PA
36781@kindex maint set target-async
36782@kindex maint show target-async
36783@item maint set target-async
36784@itemx maint show target-async
36785This controls whether @value{GDBN} targets operate in synchronous or
36786asynchronous mode (@pxref{Background Execution}). Normally the
36787default is asynchronous, if it is available; but this can be changed
36788to more easily debug problems occurring only in synchronous mode.
36789
fbea99ea
PA
36790@kindex maint set target-non-stop @var{mode} [on|off|auto]
36791@kindex maint show target-non-stop
36792@item maint set target-non-stop
36793@itemx maint show target-non-stop
36794
36795This controls whether @value{GDBN} targets always operate in non-stop
36796mode even if @code{set non-stop} is @code{off} (@pxref{Non-Stop
36797Mode}). The default is @code{auto}, meaning non-stop mode is enabled
36798if supported by the target.
36799
36800@table @code
36801@item maint set target-non-stop auto
36802This is the default mode. @value{GDBN} controls the target in
36803non-stop mode if the target supports it.
36804
36805@item maint set target-non-stop on
36806@value{GDBN} controls the target in non-stop mode even if the target
36807does not indicate support.
36808
36809@item maint set target-non-stop off
36810@value{GDBN} does not control the target in non-stop mode even if the
36811target supports it.
36812@end table
36813
bd712aed
DE
36814@kindex maint set per-command
36815@kindex maint show per-command
36816@item maint set per-command
36817@itemx maint show per-command
36818@cindex resources used by commands
09d4efe1 36819
bd712aed
DE
36820@value{GDBN} can display the resources used by each command.
36821This is useful in debugging performance problems.
36822
36823@table @code
36824@item maint set per-command space [on|off]
36825@itemx maint show per-command space
36826Enable or disable the printing of the memory used by GDB for each command.
36827If enabled, @value{GDBN} will display how much memory each command
36828took, following the command's own output.
36829This can also be requested by invoking @value{GDBN} with the
36830@option{--statistics} command-line switch (@pxref{Mode Options}).
36831
36832@item maint set per-command time [on|off]
36833@itemx maint show per-command time
36834Enable or disable the printing of the execution time of @value{GDBN}
36835for each command.
36836If enabled, @value{GDBN} will display how much time it
09d4efe1 36837took to execute each command, following the command's own output.
0a1c4d10
DE
36838Both CPU time and wallclock time are printed.
36839Printing both is useful when trying to determine whether the cost is
bd712aed 36840CPU or, e.g., disk/network latency.
0a1c4d10
DE
36841Note that the CPU time printed is for @value{GDBN} only, it does not include
36842the execution time of the inferior because there's no mechanism currently
36843to compute how much time was spent by @value{GDBN} and how much time was
36844spent by the program been debugged.
09d4efe1
EZ
36845This can also be requested by invoking @value{GDBN} with the
36846@option{--statistics} command-line switch (@pxref{Mode Options}).
36847
bd712aed
DE
36848@item maint set per-command symtab [on|off]
36849@itemx maint show per-command symtab
36850Enable or disable the printing of basic symbol table statistics
36851for each command.
36852If enabled, @value{GDBN} will display the following information:
36853
215b9f98
EZ
36854@enumerate a
36855@item
36856number of symbol tables
36857@item
36858number of primary symbol tables
36859@item
36860number of blocks in the blockvector
36861@end enumerate
bd712aed
DE
36862@end table
36863
5045b3d7
GB
36864@kindex maint set check-libthread-db
36865@kindex maint show check-libthread-db
36866@item maint set check-libthread-db [on|off]
36867@itemx maint show check-libthread-db
36868Control whether @value{GDBN} should run integrity checks on inferior
36869specific thread debugging libraries as they are loaded. The default
36870is not to perform such checks. If any check fails @value{GDBN} will
36871unload the library and continue searching for a suitable candidate as
36872described in @ref{set libthread-db-search-path}. For more information
36873about the tests, see @ref{maint check libthread-db}.
36874
bd712aed
DE
36875@kindex maint space
36876@cindex memory used by commands
36877@item maint space @var{value}
36878An alias for @code{maint set per-command space}.
36879A non-zero value enables it, zero disables it.
36880
36881@kindex maint time
36882@cindex time of command execution
36883@item maint time @var{value}
36884An alias for @code{maint set per-command time}.
36885A non-zero value enables it, zero disables it.
36886
09d4efe1
EZ
36887@kindex maint translate-address
36888@item maint translate-address @r{[}@var{section}@r{]} @var{addr}
36889Find the symbol stored at the location specified by the address
36890@var{addr} and an optional section name @var{section}. If found,
36891@value{GDBN} prints the name of the closest symbol and an offset from
36892the symbol's location to the specified address. This is similar to
36893the @code{info address} command (@pxref{Symbols}), except that this
36894command also allows to find symbols in other sections.
ae038cb0 36895
c14c28ba
PP
36896If section was not specified, the section in which the symbol was found
36897is also printed. For dynamically linked executables, the name of
36898executable or shared library containing the symbol is printed as well.
36899
8e04817f 36900@end table
c906108c 36901
9c16f35a
EZ
36902The following command is useful for non-interactive invocations of
36903@value{GDBN}, such as in the test suite.
36904
36905@table @code
36906@item set watchdog @var{nsec}
36907@kindex set watchdog
36908@cindex watchdog timer
36909@cindex timeout for commands
36910Set the maximum number of seconds @value{GDBN} will wait for the
36911target operation to finish. If this time expires, @value{GDBN}
36912reports and error and the command is aborted.
36913
36914@item show watchdog
36915Show the current setting of the target wait timeout.
36916@end table
c906108c 36917
e0ce93ac 36918@node Remote Protocol
8e04817f 36919@appendix @value{GDBN} Remote Serial Protocol
c906108c 36920
ee2d5c50
AC
36921@menu
36922* Overview::
36923* Packets::
36924* Stop Reply Packets::
36925* General Query Packets::
a1dcb23a 36926* Architecture-Specific Protocol Details::
9d29849a 36927* Tracepoint Packets::
a6b151f1 36928* Host I/O Packets::
9a6253be 36929* Interrupts::
8b23ecc4
SL
36930* Notification Packets::
36931* Remote Non-Stop::
a6f3e723 36932* Packet Acknowledgment::
ee2d5c50 36933* Examples::
79a6e687 36934* File-I/O Remote Protocol Extension::
cfa9d6d9 36935* Library List Format::
2268b414 36936* Library List Format for SVR4 Targets::
79a6e687 36937* Memory Map Format::
dc146f7c 36938* Thread List Format::
b3b9301e 36939* Traceframe Info Format::
2ae8c8e7 36940* Branch Trace Format::
f4abbc16 36941* Branch Trace Configuration Format::
ee2d5c50
AC
36942@end menu
36943
36944@node Overview
36945@section Overview
36946
8e04817f
AC
36947There may be occasions when you need to know something about the
36948protocol---for example, if there is only one serial port to your target
36949machine, you might want your program to do something special if it
36950recognizes a packet meant for @value{GDBN}.
c906108c 36951
d2c6833e 36952In the examples below, @samp{->} and @samp{<-} are used to indicate
bf06d120 36953transmitted and received data, respectively.
c906108c 36954
8e04817f
AC
36955@cindex protocol, @value{GDBN} remote serial
36956@cindex serial protocol, @value{GDBN} remote
36957@cindex remote serial protocol
8b23ecc4
SL
36958All @value{GDBN} commands and responses (other than acknowledgments
36959and notifications, see @ref{Notification Packets}) are sent as a
36960@var{packet}. A @var{packet} is introduced with the character
8e04817f
AC
36961@samp{$}, the actual @var{packet-data}, and the terminating character
36962@samp{#} followed by a two-digit @var{checksum}:
c906108c 36963
474c8240 36964@smallexample
8e04817f 36965@code{$}@var{packet-data}@code{#}@var{checksum}
474c8240 36966@end smallexample
8e04817f 36967@noindent
c906108c 36968
8e04817f
AC
36969@cindex checksum, for @value{GDBN} remote
36970@noindent
36971The two-digit @var{checksum} is computed as the modulo 256 sum of all
36972characters between the leading @samp{$} and the trailing @samp{#} (an
36973eight bit unsigned checksum).
c906108c 36974
8e04817f
AC
36975Implementors should note that prior to @value{GDBN} 5.0 the protocol
36976specification also included an optional two-digit @var{sequence-id}:
c906108c 36977
474c8240 36978@smallexample
8e04817f 36979@code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum}
474c8240 36980@end smallexample
c906108c 36981
8e04817f
AC
36982@cindex sequence-id, for @value{GDBN} remote
36983@noindent
36984That @var{sequence-id} was appended to the acknowledgment. @value{GDBN}
36985has never output @var{sequence-id}s. Stubs that handle packets added
36986since @value{GDBN} 5.0 must not accept @var{sequence-id}.
c906108c 36987
8e04817f
AC
36988When either the host or the target machine receives a packet, the first
36989response expected is an acknowledgment: either @samp{+} (to indicate
36990the package was received correctly) or @samp{-} (to request
36991retransmission):
c906108c 36992
474c8240 36993@smallexample
d2c6833e
AC
36994-> @code{$}@var{packet-data}@code{#}@var{checksum}
36995<- @code{+}
474c8240 36996@end smallexample
8e04817f 36997@noindent
53a5351d 36998
a6f3e723
SL
36999The @samp{+}/@samp{-} acknowledgments can be disabled
37000once a connection is established.
37001@xref{Packet Acknowledgment}, for details.
37002
8e04817f
AC
37003The host (@value{GDBN}) sends @var{command}s, and the target (the
37004debugging stub incorporated in your program) sends a @var{response}. In
37005the case of step and continue @var{command}s, the response is only sent
8b23ecc4
SL
37006when the operation has completed, and the target has again stopped all
37007threads in all attached processes. This is the default all-stop mode
37008behavior, but the remote protocol also supports @value{GDBN}'s non-stop
37009execution mode; see @ref{Remote Non-Stop}, for details.
c906108c 37010
8e04817f
AC
37011@var{packet-data} consists of a sequence of characters with the
37012exception of @samp{#} and @samp{$} (see @samp{X} packet for additional
37013exceptions).
c906108c 37014
ee2d5c50 37015@cindex remote protocol, field separator
0876f84a 37016Fields within the packet should be separated using @samp{,} @samp{;} or
8e04817f 37017@samp{:}. Except where otherwise noted all numbers are represented in
ee2d5c50 37018@sc{hex} with leading zeros suppressed.
c906108c 37019
8e04817f
AC
37020Implementors should note that prior to @value{GDBN} 5.0, the character
37021@samp{:} could not appear as the third character in a packet (as it
37022would potentially conflict with the @var{sequence-id}).
c906108c 37023
0876f84a
DJ
37024@cindex remote protocol, binary data
37025@anchor{Binary Data}
37026Binary data in most packets is encoded either as two hexadecimal
37027digits per byte of binary data. This allowed the traditional remote
37028protocol to work over connections which were only seven-bit clean.
37029Some packets designed more recently assume an eight-bit clean
37030connection, and use a more efficient encoding to send and receive
37031binary data.
37032
37033The binary data representation uses @code{7d} (@sc{ascii} @samp{@}})
37034as an escape character. Any escaped byte is transmitted as the escape
37035character followed by the original character XORed with @code{0x20}.
37036For example, the byte @code{0x7d} would be transmitted as the two
37037bytes @code{0x7d 0x5d}. The bytes @code{0x23} (@sc{ascii} @samp{#}),
37038@code{0x24} (@sc{ascii} @samp{$}), and @code{0x7d} (@sc{ascii}
37039@samp{@}}) must always be escaped. Responses sent by the stub
37040must also escape @code{0x2a} (@sc{ascii} @samp{*}), so that it
37041is not interpreted as the start of a run-length encoded sequence
37042(described next).
37043
1d3811f6
DJ
37044Response @var{data} can be run-length encoded to save space.
37045Run-length encoding replaces runs of identical characters with one
37046instance of the repeated character, followed by a @samp{*} and a
37047repeat count. The repeat count is itself sent encoded, to avoid
37048binary characters in @var{data}: a value of @var{n} is sent as
37049@code{@var{n}+29}. For a repeat count greater or equal to 3, this
37050produces a printable @sc{ascii} character, e.g.@: a space (@sc{ascii}
37051code 32) for a repeat count of 3. (This is because run-length
37052encoding starts to win for counts 3 or more.) Thus, for example,
37053@samp{0* } is a run-length encoding of ``0000'': the space character
37054after @samp{*} means repeat the leading @code{0} @w{@code{32 - 29 =
370553}} more times.
37056
37057The printable characters @samp{#} and @samp{$} or with a numeric value
37058greater than 126 must not be used. Runs of six repeats (@samp{#}) or
37059seven repeats (@samp{$}) can be expanded using a repeat count of only
37060five (@samp{"}). For example, @samp{00000000} can be encoded as
37061@samp{0*"00}.
c906108c 37062
8e04817f
AC
37063The error response returned for some packets includes a two character
37064error number. That number is not well defined.
c906108c 37065
f8da2bff 37066@cindex empty response, for unsupported packets
8e04817f
AC
37067For any @var{command} not supported by the stub, an empty response
37068(@samp{$#00}) should be returned. That way it is possible to extend the
37069protocol. A newer @value{GDBN} can tell if a packet is supported based
37070on that response.
c906108c 37071
393eab54
PA
37072At a minimum, a stub is required to support the @samp{g} and @samp{G}
37073commands for register access, and the @samp{m} and @samp{M} commands
37074for memory access. Stubs that only control single-threaded targets
37075can implement run control with the @samp{c} (continue), and @samp{s}
37076(step) commands. Stubs that support multi-threading targets should
37077support the @samp{vCont} command. All other commands are optional.
c906108c 37078
ee2d5c50
AC
37079@node Packets
37080@section Packets
37081
37082The following table provides a complete list of all currently defined
37083@var{command}s and their corresponding response @var{data}.
79a6e687 37084@xref{File-I/O Remote Protocol Extension}, for details about the File
9c16f35a 37085I/O extension of the remote protocol.
ee2d5c50 37086
b8ff78ce
JB
37087Each packet's description has a template showing the packet's overall
37088syntax, followed by an explanation of the packet's meaning. We
37089include spaces in some of the templates for clarity; these are not
37090part of the packet's syntax. No @value{GDBN} packet uses spaces to
37091separate its components. For example, a template like @samp{foo
37092@var{bar} @var{baz}} describes a packet beginning with the three ASCII
37093bytes @samp{foo}, followed by a @var{bar}, followed directly by a
3f94c067 37094@var{baz}. @value{GDBN} does not transmit a space character between the
b8ff78ce
JB
37095@samp{foo} and the @var{bar}, or between the @var{bar} and the
37096@var{baz}.
37097
b90a069a
SL
37098@cindex @var{thread-id}, in remote protocol
37099@anchor{thread-id syntax}
37100Several packets and replies include a @var{thread-id} field to identify
37101a thread. Normally these are positive numbers with a target-specific
37102interpretation, formatted as big-endian hex strings. A @var{thread-id}
37103can also be a literal @samp{-1} to indicate all threads, or @samp{0} to
37104pick any thread.
37105
37106In addition, the remote protocol supports a multiprocess feature in
37107which the @var{thread-id} syntax is extended to optionally include both
37108process and thread ID fields, as @samp{p@var{pid}.@var{tid}}.
37109The @var{pid} (process) and @var{tid} (thread) components each have the
37110format described above: a positive number with target-specific
37111interpretation formatted as a big-endian hex string, literal @samp{-1}
37112to indicate all processes or threads (respectively), or @samp{0} to
37113indicate an arbitrary process or thread. Specifying just a process, as
37114@samp{p@var{pid}}, is equivalent to @samp{p@var{pid}.-1}. It is an
37115error to specify all processes but a specific thread, such as
37116@samp{p-1.@var{tid}}. Note that the @samp{p} prefix is @emph{not} used
37117for those packets and replies explicitly documented to include a process
37118ID, rather than a @var{thread-id}.
37119
37120The multiprocess @var{thread-id} syntax extensions are only used if both
37121@value{GDBN} and the stub report support for the @samp{multiprocess}
37122feature using @samp{qSupported}. @xref{multiprocess extensions}, for
37123more information.
37124
8ffe2530
JB
37125Note that all packet forms beginning with an upper- or lower-case
37126letter, other than those described here, are reserved for future use.
37127
b8ff78ce 37128Here are the packet descriptions.
ee2d5c50 37129
b8ff78ce 37130@table @samp
ee2d5c50 37131
b8ff78ce
JB
37132@item !
37133@cindex @samp{!} packet
2d717e4f 37134@anchor{extended mode}
8e04817f
AC
37135Enable extended mode. In extended mode, the remote server is made
37136persistent. The @samp{R} packet is used to restart the program being
37137debugged.
ee2d5c50
AC
37138
37139Reply:
37140@table @samp
37141@item OK
8e04817f 37142The remote target both supports and has enabled extended mode.
ee2d5c50 37143@end table
c906108c 37144
b8ff78ce
JB
37145@item ?
37146@cindex @samp{?} packet
36cb1214 37147@anchor{? packet}
ee2d5c50 37148Indicate the reason the target halted. The reply is the same as for
8b23ecc4
SL
37149step and continue. This packet has a special interpretation when the
37150target is in non-stop mode; see @ref{Remote Non-Stop}.
c906108c 37151
ee2d5c50
AC
37152Reply:
37153@xref{Stop Reply Packets}, for the reply specifications.
37154
b8ff78ce
JB
37155@item A @var{arglen},@var{argnum},@var{arg},@dots{}
37156@cindex @samp{A} packet
37157Initialized @code{argv[]} array passed into program. @var{arglen}
37158specifies the number of bytes in the hex encoded byte stream
37159@var{arg}. See @code{gdbserver} for more details.
ee2d5c50
AC
37160
37161Reply:
37162@table @samp
37163@item OK
b8ff78ce
JB
37164The arguments were set.
37165@item E @var{NN}
37166An error occurred.
ee2d5c50
AC
37167@end table
37168
b8ff78ce
JB
37169@item b @var{baud}
37170@cindex @samp{b} packet
37171(Don't use this packet; its behavior is not well-defined.)
ee2d5c50
AC
37172Change the serial line speed to @var{baud}.
37173
37174JTC: @emph{When does the transport layer state change? When it's
37175received, or after the ACK is transmitted. In either case, there are
37176problems if the command or the acknowledgment packet is dropped.}
37177
37178Stan: @emph{If people really wanted to add something like this, and get
37179it working for the first time, they ought to modify ser-unix.c to send
37180some kind of out-of-band message to a specially-setup stub and have the
37181switch happen "in between" packets, so that from remote protocol's point
37182of view, nothing actually happened.}
37183
b8ff78ce
JB
37184@item B @var{addr},@var{mode}
37185@cindex @samp{B} packet
8e04817f 37186Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a
2f870471
AC
37187breakpoint at @var{addr}.
37188
b8ff78ce 37189Don't use this packet. Use the @samp{Z} and @samp{z} packets instead
2f870471 37190(@pxref{insert breakpoint or watchpoint packet}).
c906108c 37191
bacec72f 37192@cindex @samp{bc} packet
0d772ac9
MS
37193@anchor{bc}
37194@item bc
bacec72f
MS
37195Backward continue. Execute the target system in reverse. No parameter.
37196@xref{Reverse Execution}, for more information.
37197
37198Reply:
37199@xref{Stop Reply Packets}, for the reply specifications.
37200
bacec72f 37201@cindex @samp{bs} packet
0d772ac9
MS
37202@anchor{bs}
37203@item bs
bacec72f
MS
37204Backward single step. Execute one instruction in reverse. No parameter.
37205@xref{Reverse Execution}, for more information.
37206
37207Reply:
37208@xref{Stop Reply Packets}, for the reply specifications.
37209
4f553f88 37210@item c @r{[}@var{addr}@r{]}
b8ff78ce 37211@cindex @samp{c} packet
697aa1b7
EZ
37212Continue at @var{addr}, which is the address to resume. If @var{addr}
37213is omitted, resume at current address.
c906108c 37214
393eab54
PA
37215This packet is deprecated for multi-threading support. @xref{vCont
37216packet}.
37217
ee2d5c50
AC
37218Reply:
37219@xref{Stop Reply Packets}, for the reply specifications.
37220
4f553f88 37221@item C @var{sig}@r{[};@var{addr}@r{]}
b8ff78ce 37222@cindex @samp{C} packet
8e04817f 37223Continue with signal @var{sig} (hex signal number). If
b8ff78ce 37224@samp{;@var{addr}} is omitted, resume at same address.
c906108c 37225
393eab54
PA
37226This packet is deprecated for multi-threading support. @xref{vCont
37227packet}.
37228
ee2d5c50
AC
37229Reply:
37230@xref{Stop Reply Packets}, for the reply specifications.
c906108c 37231
b8ff78ce
JB
37232@item d
37233@cindex @samp{d} packet
ee2d5c50
AC
37234Toggle debug flag.
37235
b8ff78ce
JB
37236Don't use this packet; instead, define a general set packet
37237(@pxref{General Query Packets}).
ee2d5c50 37238
b8ff78ce 37239@item D
b90a069a 37240@itemx D;@var{pid}
b8ff78ce 37241@cindex @samp{D} packet
b90a069a
SL
37242The first form of the packet is used to detach @value{GDBN} from the
37243remote system. It is sent to the remote target
07f31aa6 37244before @value{GDBN} disconnects via the @code{detach} command.
ee2d5c50 37245
b90a069a
SL
37246The second form, including a process ID, is used when multiprocess
37247protocol extensions are enabled (@pxref{multiprocess extensions}), to
37248detach only a specific process. The @var{pid} is specified as a
37249big-endian hex string.
37250
ee2d5c50
AC
37251Reply:
37252@table @samp
10fac096
NW
37253@item OK
37254for success
b8ff78ce 37255@item E @var{NN}
10fac096 37256for an error
ee2d5c50 37257@end table
c906108c 37258
b8ff78ce
JB
37259@item F @var{RC},@var{EE},@var{CF};@var{XX}
37260@cindex @samp{F} packet
37261A reply from @value{GDBN} to an @samp{F} packet sent by the target.
37262This is part of the File-I/O protocol extension. @xref{File-I/O
79a6e687 37263Remote Protocol Extension}, for the specification.
ee2d5c50 37264
b8ff78ce 37265@item g
ee2d5c50 37266@anchor{read registers packet}
b8ff78ce 37267@cindex @samp{g} packet
ee2d5c50
AC
37268Read general registers.
37269
37270Reply:
37271@table @samp
37272@item @var{XX@dots{}}
8e04817f
AC
37273Each byte of register data is described by two hex digits. The bytes
37274with the register are transmitted in target byte order. The size of
b8ff78ce 37275each register and their position within the @samp{g} packet are
4a9bb1df 37276determined by the @value{GDBN} internal gdbarch functions
4435e1cc 37277@code{DEPRECATED_REGISTER_RAW_SIZE} and @code{gdbarch_register_name}.
ad196637
PA
37278
37279When reading registers from a trace frame (@pxref{Analyze Collected
37280Data,,Using the Collected Data}), the stub may also return a string of
37281literal @samp{x}'s in place of the register data digits, to indicate
37282that the corresponding register has not been collected, thus its value
37283is unavailable. For example, for an architecture with 4 registers of
372844 bytes each, the following reply indicates to @value{GDBN} that
37285registers 0 and 2 have not been collected, while registers 1 and 3
37286have been collected, and both have zero value:
37287
37288@smallexample
37289-> @code{g}
37290<- @code{xxxxxxxx00000000xxxxxxxx00000000}
37291@end smallexample
37292
b8ff78ce 37293@item E @var{NN}
ee2d5c50
AC
37294for an error.
37295@end table
c906108c 37296
b8ff78ce
JB
37297@item G @var{XX@dots{}}
37298@cindex @samp{G} packet
37299Write general registers. @xref{read registers packet}, for a
37300description of the @var{XX@dots{}} data.
ee2d5c50
AC
37301
37302Reply:
37303@table @samp
37304@item OK
37305for success
b8ff78ce 37306@item E @var{NN}
ee2d5c50
AC
37307for an error
37308@end table
37309
393eab54 37310@item H @var{op} @var{thread-id}
b8ff78ce 37311@cindex @samp{H} packet
8e04817f 37312Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g},
697aa1b7
EZ
37313@samp{G}, et.al.). Depending on the operation to be performed, @var{op}
37314should be @samp{c} for step and continue operations (note that this
393eab54 37315is deprecated, supporting the @samp{vCont} command is a better
697aa1b7 37316option), and @samp{g} for other operations. The thread designator
393eab54
PA
37317@var{thread-id} has the format and interpretation described in
37318@ref{thread-id syntax}.
ee2d5c50
AC
37319
37320Reply:
37321@table @samp
37322@item OK
37323for success
b8ff78ce 37324@item E @var{NN}
ee2d5c50
AC
37325for an error
37326@end table
c906108c 37327
8e04817f
AC
37328@c FIXME: JTC:
37329@c 'H': How restrictive (or permissive) is the thread model. If a
37330@c thread is selected and stopped, are other threads allowed
37331@c to continue to execute? As I mentioned above, I think the
37332@c semantics of each command when a thread is selected must be
37333@c described. For example:
37334@c
37335@c 'g': If the stub supports threads and a specific thread is
37336@c selected, returns the register block from that thread;
37337@c otherwise returns current registers.
37338@c
37339@c 'G' If the stub supports threads and a specific thread is
37340@c selected, sets the registers of the register block of
37341@c that thread; otherwise sets current registers.
c906108c 37342
b8ff78ce 37343@item i @r{[}@var{addr}@r{[},@var{nnn}@r{]]}
ee2d5c50 37344@anchor{cycle step packet}
b8ff78ce
JB
37345@cindex @samp{i} packet
37346Step the remote target by a single clock cycle. If @samp{,@var{nnn}} is
8e04817f
AC
37347present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle
37348step starting at that address.
c906108c 37349
b8ff78ce
JB
37350@item I
37351@cindex @samp{I} packet
37352Signal, then cycle step. @xref{step with signal packet}. @xref{cycle
37353step packet}.
ee2d5c50 37354
b8ff78ce
JB
37355@item k
37356@cindex @samp{k} packet
37357Kill request.
c906108c 37358
36cb1214
HZ
37359The exact effect of this packet is not specified.
37360
37361For a bare-metal target, it may power cycle or reset the target
37362system. For that reason, the @samp{k} packet has no reply.
37363
37364For a single-process target, it may kill that process if possible.
37365
37366A multiple-process target may choose to kill just one process, or all
37367that are under @value{GDBN}'s control. For more precise control, use
37368the vKill packet (@pxref{vKill packet}).
37369
37370If the target system immediately closes the connection in response to
37371@samp{k}, @value{GDBN} does not consider the lack of packet
37372acknowledgment to be an error, and assumes the kill was successful.
37373
37374If connected using @kbd{target extended-remote}, and the target does
37375not close the connection in response to a kill request, @value{GDBN}
37376probes the target state as if a new connection was opened
37377(@pxref{? packet}).
c906108c 37378
b8ff78ce
JB
37379@item m @var{addr},@var{length}
37380@cindex @samp{m} packet
a86c90e6
SM
37381Read @var{length} addressable memory units starting at address @var{addr}
37382(@pxref{addressable memory unit}). Note that @var{addr} may not be aligned to
37383any particular boundary.
fb031cdf
JB
37384
37385The stub need not use any particular size or alignment when gathering
37386data from memory for the response; even if @var{addr} is word-aligned
37387and @var{length} is a multiple of the word size, the stub is free to
37388use byte accesses, or not. For this reason, this packet may not be
37389suitable for accessing memory-mapped I/O devices.
c43c5473
JB
37390@cindex alignment of remote memory accesses
37391@cindex size of remote memory accesses
37392@cindex memory, alignment and size of remote accesses
c906108c 37393
ee2d5c50
AC
37394Reply:
37395@table @samp
37396@item @var{XX@dots{}}
a86c90e6
SM
37397Memory contents; each byte is transmitted as a two-digit hexadecimal number.
37398The reply may contain fewer addressable memory units than requested if the
b8ff78ce
JB
37399server was able to read only part of the region of memory.
37400@item E @var{NN}
ee2d5c50
AC
37401@var{NN} is errno
37402@end table
37403
b8ff78ce
JB
37404@item M @var{addr},@var{length}:@var{XX@dots{}}
37405@cindex @samp{M} packet
a86c90e6
SM
37406Write @var{length} addressable memory units starting at address @var{addr}
37407(@pxref{addressable memory unit}). The data is given by @var{XX@dots{}}; each
37408byte is transmitted as a two-digit hexadecimal number.
ee2d5c50
AC
37409
37410Reply:
37411@table @samp
37412@item OK
37413for success
b8ff78ce 37414@item E @var{NN}
8e04817f
AC
37415for an error (this includes the case where only part of the data was
37416written).
ee2d5c50 37417@end table
c906108c 37418
b8ff78ce
JB
37419@item p @var{n}
37420@cindex @samp{p} packet
37421Read the value of register @var{n}; @var{n} is in hex.
2e868123
AC
37422@xref{read registers packet}, for a description of how the returned
37423register value is encoded.
ee2d5c50
AC
37424
37425Reply:
37426@table @samp
2e868123
AC
37427@item @var{XX@dots{}}
37428the register's value
b8ff78ce 37429@item E @var{NN}
2e868123 37430for an error
d57350ea 37431@item @w{}
2e868123 37432Indicating an unrecognized @var{query}.
ee2d5c50
AC
37433@end table
37434
b8ff78ce 37435@item P @var{n@dots{}}=@var{r@dots{}}
ee2d5c50 37436@anchor{write register packet}
b8ff78ce
JB
37437@cindex @samp{P} packet
37438Write register @var{n@dots{}} with value @var{r@dots{}}. The register
599b237a 37439number @var{n} is in hexadecimal, and @var{r@dots{}} contains two hex
8e04817f 37440digits for each byte in the register (target byte order).
c906108c 37441
ee2d5c50
AC
37442Reply:
37443@table @samp
37444@item OK
37445for success
b8ff78ce 37446@item E @var{NN}
ee2d5c50
AC
37447for an error
37448@end table
37449
5f3bebba
JB
37450@item q @var{name} @var{params}@dots{}
37451@itemx Q @var{name} @var{params}@dots{}
b8ff78ce 37452@cindex @samp{q} packet
b8ff78ce 37453@cindex @samp{Q} packet
5f3bebba
JB
37454General query (@samp{q}) and set (@samp{Q}). These packets are
37455described fully in @ref{General Query Packets}.
c906108c 37456
b8ff78ce
JB
37457@item r
37458@cindex @samp{r} packet
8e04817f 37459Reset the entire system.
c906108c 37460
b8ff78ce 37461Don't use this packet; use the @samp{R} packet instead.
ee2d5c50 37462
b8ff78ce
JB
37463@item R @var{XX}
37464@cindex @samp{R} packet
697aa1b7 37465Restart the program being debugged. The @var{XX}, while needed, is ignored.
2d717e4f 37466This packet is only available in extended mode (@pxref{extended mode}).
ee2d5c50 37467
8e04817f 37468The @samp{R} packet has no reply.
ee2d5c50 37469
4f553f88 37470@item s @r{[}@var{addr}@r{]}
b8ff78ce 37471@cindex @samp{s} packet
697aa1b7 37472Single step, resuming at @var{addr}. If
b8ff78ce 37473@var{addr} is omitted, resume at same address.
c906108c 37474
393eab54
PA
37475This packet is deprecated for multi-threading support. @xref{vCont
37476packet}.
37477
ee2d5c50
AC
37478Reply:
37479@xref{Stop Reply Packets}, for the reply specifications.
37480
4f553f88 37481@item S @var{sig}@r{[};@var{addr}@r{]}
ee2d5c50 37482@anchor{step with signal packet}
b8ff78ce
JB
37483@cindex @samp{S} packet
37484Step with signal. This is analogous to the @samp{C} packet, but
37485requests a single-step, rather than a normal resumption of execution.
c906108c 37486
393eab54
PA
37487This packet is deprecated for multi-threading support. @xref{vCont
37488packet}.
37489
ee2d5c50
AC
37490Reply:
37491@xref{Stop Reply Packets}, for the reply specifications.
37492
b8ff78ce
JB
37493@item t @var{addr}:@var{PP},@var{MM}
37494@cindex @samp{t} packet
8e04817f 37495Search backwards starting at address @var{addr} for a match with pattern
697aa1b7
EZ
37496@var{PP} and mask @var{MM}, both of which are are 4 byte long.
37497There must be at least 3 digits in @var{addr}.
c906108c 37498
b90a069a 37499@item T @var{thread-id}
b8ff78ce 37500@cindex @samp{T} packet
b90a069a 37501Find out if the thread @var{thread-id} is alive. @xref{thread-id syntax}.
c906108c 37502
ee2d5c50
AC
37503Reply:
37504@table @samp
37505@item OK
37506thread is still alive
b8ff78ce 37507@item E @var{NN}
ee2d5c50
AC
37508thread is dead
37509@end table
37510
b8ff78ce
JB
37511@item v
37512Packets starting with @samp{v} are identified by a multi-letter name,
37513up to the first @samp{;} or @samp{?} (or the end of the packet).
86d30acc 37514
2d717e4f
DJ
37515@item vAttach;@var{pid}
37516@cindex @samp{vAttach} packet
8b23ecc4
SL
37517Attach to a new process with the specified process ID @var{pid}.
37518The process ID is a
37519hexadecimal integer identifying the process. In all-stop mode, all
37520threads in the attached process are stopped; in non-stop mode, it may be
37521attached without being stopped if that is supported by the target.
37522
37523@c In non-stop mode, on a successful vAttach, the stub should set the
37524@c current thread to a thread of the newly-attached process. After
37525@c attaching, GDB queries for the attached process's thread ID with qC.
37526@c Also note that, from a user perspective, whether or not the
37527@c target is stopped on attach in non-stop mode depends on whether you
37528@c use the foreground or background version of the attach command, not
37529@c on what vAttach does; GDB does the right thing with respect to either
37530@c stopping or restarting threads.
2d717e4f
DJ
37531
37532This packet is only available in extended mode (@pxref{extended mode}).
37533
37534Reply:
37535@table @samp
37536@item E @var{nn}
37537for an error
37538@item @r{Any stop packet}
8b23ecc4
SL
37539for success in all-stop mode (@pxref{Stop Reply Packets})
37540@item OK
37541for success in non-stop mode (@pxref{Remote Non-Stop})
2d717e4f
DJ
37542@end table
37543
b90a069a 37544@item vCont@r{[};@var{action}@r{[}:@var{thread-id}@r{]]}@dots{}
b8ff78ce 37545@cindex @samp{vCont} packet
393eab54 37546@anchor{vCont packet}
b8ff78ce 37547Resume the inferior, specifying different actions for each thread.
ca6eff59
PA
37548
37549For each inferior thread, the leftmost action with a matching
37550@var{thread-id} is applied. Threads that don't match any action
37551remain in their current state. Thread IDs are specified using the
37552syntax described in @ref{thread-id syntax}. If multiprocess
37553extensions (@pxref{multiprocess extensions}) are supported, actions
37554can be specified to match all threads in a process by using the
37555@samp{p@var{pid}.-1} form of the @var{thread-id}. An action with no
39402e6c
PA
37556@var{thread-id} matches all threads. Specifying no actions is an
37557error.
b90a069a
SL
37558
37559Currently supported actions are:
86d30acc 37560
b8ff78ce 37561@table @samp
86d30acc
DJ
37562@item c
37563Continue.
b8ff78ce 37564@item C @var{sig}
8b23ecc4 37565Continue with signal @var{sig}. The signal @var{sig} should be two hex digits.
86d30acc
DJ
37566@item s
37567Step.
b8ff78ce 37568@item S @var{sig}
8b23ecc4
SL
37569Step with signal @var{sig}. The signal @var{sig} should be two hex digits.
37570@item t
37571Stop.
c1e36e3e
PA
37572@item r @var{start},@var{end}
37573Step once, and then keep stepping as long as the thread stops at
37574addresses between @var{start} (inclusive) and @var{end} (exclusive).
37575The remote stub reports a stop reply when either the thread goes out
37576of the range or is stopped due to an unrelated reason, such as hitting
37577a breakpoint. @xref{range stepping}.
37578
37579If the range is empty (@var{start} == @var{end}), then the action
37580becomes equivalent to the @samp{s} action. In other words,
37581single-step once, and report the stop (even if the stepped instruction
37582jumps to @var{start}).
37583
37584(A stop reply may be sent at any point even if the PC is still within
37585the stepping range; for example, it is valid to implement this packet
37586in a degenerate way as a single instruction step operation.)
37587
86d30acc
DJ
37588@end table
37589
8b23ecc4
SL
37590The optional argument @var{addr} normally associated with the
37591@samp{c}, @samp{C}, @samp{s}, and @samp{S} packets is
b8ff78ce 37592not supported in @samp{vCont}.
86d30acc 37593
08a0efd0
PA
37594The @samp{t} action is only relevant in non-stop mode
37595(@pxref{Remote Non-Stop}) and may be ignored by the stub otherwise.
8b23ecc4
SL
37596A stop reply should be generated for any affected thread not already stopped.
37597When a thread is stopped by means of a @samp{t} action,
37598the corresponding stop reply should indicate that the thread has stopped with
37599signal @samp{0}, regardless of whether the target uses some other signal
37600as an implementation detail.
37601
ca6eff59
PA
37602The server must ignore @samp{c}, @samp{C}, @samp{s}, @samp{S}, and
37603@samp{r} actions for threads that are already running. Conversely,
37604the server must ignore @samp{t} actions for threads that are already
37605stopped.
37606
37607@emph{Note:} In non-stop mode, a thread is considered running until
37608@value{GDBN} acknowleges an asynchronous stop notification for it with
37609the @samp{vStopped} packet (@pxref{Remote Non-Stop}).
37610
4220b2f8 37611The stub must support @samp{vCont} if it reports support for
ca6eff59 37612multiprocess extensions (@pxref{multiprocess extensions}).
4220b2f8 37613
86d30acc
DJ
37614Reply:
37615@xref{Stop Reply Packets}, for the reply specifications.
37616
b8ff78ce
JB
37617@item vCont?
37618@cindex @samp{vCont?} packet
d3e8051b 37619Request a list of actions supported by the @samp{vCont} packet.
86d30acc
DJ
37620
37621Reply:
37622@table @samp
b8ff78ce
JB
37623@item vCont@r{[};@var{action}@dots{}@r{]}
37624The @samp{vCont} packet is supported. Each @var{action} is a supported
37625command in the @samp{vCont} packet.
d57350ea 37626@item @w{}
b8ff78ce 37627The @samp{vCont} packet is not supported.
86d30acc 37628@end table
ee2d5c50 37629
de979965
PA
37630@anchor{vCtrlC packet}
37631@item vCtrlC
37632@cindex @samp{vCtrlC} packet
37633Interrupt remote target as if a control-C was pressed on the remote
37634terminal. This is the equivalent to reacting to the @code{^C}
37635(@samp{\003}, the control-C character) character in all-stop mode
37636while the target is running, except this works in non-stop mode.
37637@xref{interrupting remote targets}, for more info on the all-stop
37638variant.
37639
37640Reply:
37641@table @samp
37642@item E @var{nn}
37643for an error
37644@item OK
37645for success
37646@end table
37647
a6b151f1
DJ
37648@item vFile:@var{operation}:@var{parameter}@dots{}
37649@cindex @samp{vFile} packet
37650Perform a file operation on the target system. For details,
37651see @ref{Host I/O Packets}.
37652
68437a39
DJ
37653@item vFlashErase:@var{addr},@var{length}
37654@cindex @samp{vFlashErase} packet
37655Direct the stub to erase @var{length} bytes of flash starting at
37656@var{addr}. The region may enclose any number of flash blocks, but
37657its start and end must fall on block boundaries, as indicated by the
79a6e687
BW
37658flash block size appearing in the memory map (@pxref{Memory Map
37659Format}). @value{GDBN} groups flash memory programming operations
68437a39
DJ
37660together, and sends a @samp{vFlashDone} request after each group; the
37661stub is allowed to delay erase operation until the @samp{vFlashDone}
37662packet is received.
37663
37664Reply:
37665@table @samp
37666@item OK
37667for success
37668@item E @var{NN}
37669for an error
37670@end table
37671
37672@item vFlashWrite:@var{addr}:@var{XX@dots{}}
37673@cindex @samp{vFlashWrite} packet
37674Direct the stub to write data to flash address @var{addr}. The data
37675is passed in binary form using the same encoding as for the @samp{X}
37676packet (@pxref{Binary Data}). The memory ranges specified by
37677@samp{vFlashWrite} packets preceding a @samp{vFlashDone} packet must
37678not overlap, and must appear in order of increasing addresses
37679(although @samp{vFlashErase} packets for higher addresses may already
37680have been received; the ordering is guaranteed only between
37681@samp{vFlashWrite} packets). If a packet writes to an address that was
37682neither erased by a preceding @samp{vFlashErase} packet nor by some other
37683target-specific method, the results are unpredictable.
37684
37685
37686Reply:
37687@table @samp
37688@item OK
37689for success
37690@item E.memtype
37691for vFlashWrite addressing non-flash memory
37692@item E @var{NN}
37693for an error
37694@end table
37695
37696@item vFlashDone
37697@cindex @samp{vFlashDone} packet
37698Indicate to the stub that flash programming operation is finished.
37699The stub is permitted to delay or batch the effects of a group of
37700@samp{vFlashErase} and @samp{vFlashWrite} packets until a
37701@samp{vFlashDone} packet is received. The contents of the affected
37702regions of flash memory are unpredictable until the @samp{vFlashDone}
37703request is completed.
37704
b90a069a
SL
37705@item vKill;@var{pid}
37706@cindex @samp{vKill} packet
36cb1214 37707@anchor{vKill packet}
697aa1b7 37708Kill the process with the specified process ID @var{pid}, which is a
b90a069a
SL
37709hexadecimal integer identifying the process. This packet is used in
37710preference to @samp{k} when multiprocess protocol extensions are
37711supported; see @ref{multiprocess extensions}.
37712
37713Reply:
37714@table @samp
37715@item E @var{nn}
37716for an error
37717@item OK
37718for success
37719@end table
37720
176efed1
AB
37721@item vMustReplyEmpty
37722@cindex @samp{vMustReplyEmpty} packet
37723The correct reply to an unknown @samp{v} packet is to return the empty
37724string, however, some older versions of @command{gdbserver} would
37725incorrectly return @samp{OK} for unknown @samp{v} packets.
37726
37727The @samp{vMustReplyEmpty} is used as a feature test to check how
37728@command{gdbserver} handles unknown packets, it is important that this
37729packet be handled in the same way as other unknown @samp{v} packets.
37730If this packet is handled differently to other unknown @samp{v}
37731packets then it is possile that @value{GDBN} may run into problems in
37732other areas, specifically around use of @samp{vFile:setfs:}.
37733
2d717e4f
DJ
37734@item vRun;@var{filename}@r{[};@var{argument}@r{]}@dots{}
37735@cindex @samp{vRun} packet
37736Run the program @var{filename}, passing it each @var{argument} on its
37737command line. The file and arguments are hex-encoded strings. If
37738@var{filename} is an empty string, the stub may use a default program
37739(e.g.@: the last program run). The program is created in the stopped
9b562ab8 37740state.
2d717e4f 37741
8b23ecc4
SL
37742@c FIXME: What about non-stop mode?
37743
2d717e4f
DJ
37744This packet is only available in extended mode (@pxref{extended mode}).
37745
37746Reply:
37747@table @samp
37748@item E @var{nn}
37749for an error
37750@item @r{Any stop packet}
37751for success (@pxref{Stop Reply Packets})
37752@end table
37753
8b23ecc4 37754@item vStopped
8b23ecc4 37755@cindex @samp{vStopped} packet
8dbe8ece 37756@xref{Notification Packets}.
8b23ecc4 37757
b8ff78ce 37758@item X @var{addr},@var{length}:@var{XX@dots{}}
9a6253be 37759@anchor{X packet}
b8ff78ce
JB
37760@cindex @samp{X} packet
37761Write data to memory, where the data is transmitted in binary.
a86c90e6
SM
37762Memory is specified by its address @var{addr} and number of addressable memory
37763units @var{length} (@pxref{addressable memory unit});
0876f84a 37764@samp{@var{XX}@dots{}} is binary data (@pxref{Binary Data}).
c906108c 37765
ee2d5c50
AC
37766Reply:
37767@table @samp
37768@item OK
37769for success
b8ff78ce 37770@item E @var{NN}
ee2d5c50
AC
37771for an error
37772@end table
37773
a1dcb23a
DJ
37774@item z @var{type},@var{addr},@var{kind}
37775@itemx Z @var{type},@var{addr},@var{kind}
2f870471 37776@anchor{insert breakpoint or watchpoint packet}
b8ff78ce
JB
37777@cindex @samp{z} packet
37778@cindex @samp{Z} packets
37779Insert (@samp{Z}) or remove (@samp{z}) a @var{type} breakpoint or
a1dcb23a 37780watchpoint starting at address @var{address} of kind @var{kind}.
ee2d5c50 37781
2f870471
AC
37782Each breakpoint and watchpoint packet @var{type} is documented
37783separately.
37784
512217c7
AC
37785@emph{Implementation notes: A remote target shall return an empty string
37786for an unrecognized breakpoint or watchpoint packet @var{type}. A
37787remote target shall support either both or neither of a given
b8ff78ce 37788@samp{Z@var{type}@dots{}} and @samp{z@var{type}@dots{}} packet pair. To
2f870471
AC
37789avoid potential problems with duplicate packets, the operations should
37790be implemented in an idempotent way.}
37791
a1dcb23a 37792@item z0,@var{addr},@var{kind}
d3ce09f5 37793@itemx Z0,@var{addr},@var{kind}@r{[};@var{cond_list}@dots{}@r{]}@r{[};cmds:@var{persist},@var{cmd_list}@dots{}@r{]}
b8ff78ce
JB
37794@cindex @samp{z0} packet
37795@cindex @samp{Z0} packet
4435e1cc 37796Insert (@samp{Z0}) or remove (@samp{z0}) a software breakpoint at address
a1dcb23a 37797@var{addr} of type @var{kind}.
2f870471 37798
4435e1cc 37799A software breakpoint is implemented by replacing the instruction at
2f870471 37800@var{addr} with a software breakpoint or trap instruction. The
4435e1cc
TT
37801@var{kind} is target-specific and typically indicates the size of the
37802breakpoint in bytes that should be inserted. E.g., the @sc{arm} and
37803@sc{mips} can insert either a 2 or 4 byte breakpoint. Some
37804architectures have additional meanings for @var{kind}
37805(@pxref{Architecture-Specific Protocol Details}); if no
37806architecture-specific value is being used, it should be @samp{0}.
37807@var{kind} is hex-encoded. @var{cond_list} is an optional list of
37808conditional expressions in bytecode form that should be evaluated on
37809the target's side. These are the conditions that should be taken into
37810consideration when deciding if the breakpoint trigger should be
37811reported back to @value{GDBN}.
83364271 37812
f7e6eed5 37813See also the @samp{swbreak} stop reason (@pxref{swbreak stop reason})
4435e1cc 37814for how to best report a software breakpoint event to @value{GDBN}.
f7e6eed5 37815
83364271
LM
37816The @var{cond_list} parameter is comprised of a series of expressions,
37817concatenated without separators. Each expression has the following form:
37818
37819@table @samp
37820
37821@item X @var{len},@var{expr}
37822@var{len} is the length of the bytecode expression and @var{expr} is the
37823actual conditional expression in bytecode form.
37824
37825@end table
37826
d3ce09f5
SS
37827The optional @var{cmd_list} parameter introduces commands that may be
37828run on the target, rather than being reported back to @value{GDBN}.
37829The parameter starts with a numeric flag @var{persist}; if the flag is
37830nonzero, then the breakpoint may remain active and the commands
37831continue to be run even when @value{GDBN} disconnects from the target.
37832Following this flag is a series of expressions concatenated with no
37833separators. Each expression has the following form:
37834
37835@table @samp
37836
37837@item X @var{len},@var{expr}
37838@var{len} is the length of the bytecode expression and @var{expr} is the
0968fbae 37839actual commands expression in bytecode form.
d3ce09f5
SS
37840
37841@end table
37842
2f870471 37843@emph{Implementation note: It is possible for a target to copy or move
4435e1cc 37844code that contains software breakpoints (e.g., when implementing
2f870471
AC
37845overlays). The behavior of this packet, in the presence of such a
37846target, is not defined.}
c906108c 37847
ee2d5c50
AC
37848Reply:
37849@table @samp
2f870471
AC
37850@item OK
37851success
d57350ea 37852@item @w{}
2f870471 37853not supported
b8ff78ce 37854@item E @var{NN}
ee2d5c50 37855for an error
2f870471
AC
37856@end table
37857
a1dcb23a 37858@item z1,@var{addr},@var{kind}
4435e1cc 37859@itemx Z1,@var{addr},@var{kind}@r{[};@var{cond_list}@dots{}@r{]}@r{[};cmds:@var{persist},@var{cmd_list}@dots{}@r{]}
b8ff78ce
JB
37860@cindex @samp{z1} packet
37861@cindex @samp{Z1} packet
37862Insert (@samp{Z1}) or remove (@samp{z1}) a hardware breakpoint at
a1dcb23a 37863address @var{addr}.
2f870471
AC
37864
37865A hardware breakpoint is implemented using a mechanism that is not
4435e1cc
TT
37866dependent on being able to modify the target's memory. The
37867@var{kind}, @var{cond_list}, and @var{cmd_list} arguments have the
37868same meaning as in @samp{Z0} packets.
2f870471
AC
37869
37870@emph{Implementation note: A hardware breakpoint is not affected by code
37871movement.}
37872
37873Reply:
37874@table @samp
ee2d5c50 37875@item OK
2f870471 37876success
d57350ea 37877@item @w{}
2f870471 37878not supported
b8ff78ce 37879@item E @var{NN}
2f870471
AC
37880for an error
37881@end table
37882
a1dcb23a
DJ
37883@item z2,@var{addr},@var{kind}
37884@itemx Z2,@var{addr},@var{kind}
b8ff78ce
JB
37885@cindex @samp{z2} packet
37886@cindex @samp{Z2} packet
a1dcb23a 37887Insert (@samp{Z2}) or remove (@samp{z2}) a write watchpoint at @var{addr}.
697aa1b7 37888The number of bytes to watch is specified by @var{kind}.
2f870471
AC
37889
37890Reply:
37891@table @samp
37892@item OK
37893success
d57350ea 37894@item @w{}
2f870471 37895not supported
b8ff78ce 37896@item E @var{NN}
2f870471
AC
37897for an error
37898@end table
37899
a1dcb23a
DJ
37900@item z3,@var{addr},@var{kind}
37901@itemx Z3,@var{addr},@var{kind}
b8ff78ce
JB
37902@cindex @samp{z3} packet
37903@cindex @samp{Z3} packet
a1dcb23a 37904Insert (@samp{Z3}) or remove (@samp{z3}) a read watchpoint at @var{addr}.
697aa1b7 37905The number of bytes to watch is specified by @var{kind}.
2f870471
AC
37906
37907Reply:
37908@table @samp
37909@item OK
37910success
d57350ea 37911@item @w{}
2f870471 37912not supported
b8ff78ce 37913@item E @var{NN}
2f870471
AC
37914for an error
37915@end table
37916
a1dcb23a
DJ
37917@item z4,@var{addr},@var{kind}
37918@itemx Z4,@var{addr},@var{kind}
b8ff78ce
JB
37919@cindex @samp{z4} packet
37920@cindex @samp{Z4} packet
a1dcb23a 37921Insert (@samp{Z4}) or remove (@samp{z4}) an access watchpoint at @var{addr}.
697aa1b7 37922The number of bytes to watch is specified by @var{kind}.
2f870471
AC
37923
37924Reply:
37925@table @samp
37926@item OK
37927success
d57350ea 37928@item @w{}
2f870471 37929not supported
b8ff78ce 37930@item E @var{NN}
2f870471 37931for an error
ee2d5c50
AC
37932@end table
37933
37934@end table
c906108c 37935
ee2d5c50
AC
37936@node Stop Reply Packets
37937@section Stop Reply Packets
37938@cindex stop reply packets
c906108c 37939
8b23ecc4
SL
37940The @samp{C}, @samp{c}, @samp{S}, @samp{s}, @samp{vCont},
37941@samp{vAttach}, @samp{vRun}, @samp{vStopped}, and @samp{?} packets can
37942receive any of the below as a reply. Except for @samp{?}
37943and @samp{vStopped}, that reply is only returned
b8ff78ce 37944when the target halts. In the below the exact meaning of @dfn{signal
89be2091
DJ
37945number} is defined by the header @file{include/gdb/signals.h} in the
37946@value{GDBN} source code.
c906108c 37947
4435e1cc
TT
37948In non-stop mode, the server will simply reply @samp{OK} to commands
37949such as @samp{vCont}; any stop will be the subject of a future
37950notification. @xref{Remote Non-Stop}.
37951
b8ff78ce
JB
37952As in the description of request packets, we include spaces in the
37953reply templates for clarity; these are not part of the reply packet's
37954syntax. No @value{GDBN} stop reply packet uses spaces to separate its
37955components.
c906108c 37956
b8ff78ce 37957@table @samp
ee2d5c50 37958
b8ff78ce 37959@item S @var{AA}
599b237a 37960The program received signal number @var{AA} (a two-digit hexadecimal
940178d3
JB
37961number). This is equivalent to a @samp{T} response with no
37962@var{n}:@var{r} pairs.
c906108c 37963
b8ff78ce
JB
37964@item T @var{AA} @var{n1}:@var{r1};@var{n2}:@var{r2};@dots{}
37965@cindex @samp{T} packet reply
599b237a 37966The program received signal number @var{AA} (a two-digit hexadecimal
940178d3
JB
37967number). This is equivalent to an @samp{S} response, except that the
37968@samp{@var{n}:@var{r}} pairs can carry values of important registers
37969and other information directly in the stop reply packet, reducing
37970round-trip latency. Single-step and breakpoint traps are reported
37971this way. Each @samp{@var{n}:@var{r}} pair is interpreted as follows:
cfa9d6d9
DJ
37972
37973@itemize @bullet
b8ff78ce 37974@item
599b237a 37975If @var{n} is a hexadecimal number, it is a register number, and the
697aa1b7 37976corresponding @var{r} gives that register's value. The data @var{r} is a
b8ff78ce
JB
37977series of bytes in target byte order, with each byte given by a
37978two-digit hex number.
cfa9d6d9 37979
b8ff78ce 37980@item
b90a069a
SL
37981If @var{n} is @samp{thread}, then @var{r} is the @var{thread-id} of
37982the stopped thread, as specified in @ref{thread-id syntax}.
cfa9d6d9 37983
dc146f7c
VP
37984@item
37985If @var{n} is @samp{core}, then @var{r} is the hexadecimal number of
37986the core on which the stop event was detected.
37987
b8ff78ce 37988@item
cfa9d6d9
DJ
37989If @var{n} is a recognized @dfn{stop reason}, it describes a more
37990specific event that stopped the target. The currently defined stop
697aa1b7 37991reasons are listed below. The @var{aa} should be @samp{05}, the trap
cfa9d6d9
DJ
37992signal. At most one stop reason should be present.
37993
b8ff78ce
JB
37994@item
37995Otherwise, @value{GDBN} should ignore this @samp{@var{n}:@var{r}} pair
37996and go on to the next; this allows us to extend the protocol in the
37997future.
cfa9d6d9
DJ
37998@end itemize
37999
38000The currently defined stop reasons are:
38001
38002@table @samp
38003@item watch
38004@itemx rwatch
38005@itemx awatch
38006The packet indicates a watchpoint hit, and @var{r} is the data address, in
38007hex.
38008
82075af2
JS
38009@item syscall_entry
38010@itemx syscall_return
38011The packet indicates a syscall entry or return, and @var{r} is the
38012syscall number, in hex.
38013
cfa9d6d9
DJ
38014@cindex shared library events, remote reply
38015@item library
38016The packet indicates that the loaded libraries have changed.
38017@value{GDBN} should use @samp{qXfer:libraries:read} to fetch a new
697aa1b7 38018list of loaded libraries. The @var{r} part is ignored.
bacec72f
MS
38019
38020@cindex replay log events, remote reply
38021@item replaylog
38022The packet indicates that the target cannot continue replaying
38023logged execution events, because it has reached the end (or the
38024beginning when executing backward) of the log. The value of @var{r}
38025will be either @samp{begin} or @samp{end}. @xref{Reverse Execution},
38026for more information.
f7e6eed5
PA
38027
38028@item swbreak
38029@anchor{swbreak stop reason}
4435e1cc 38030The packet indicates a software breakpoint instruction was executed,
f7e6eed5
PA
38031irrespective of whether it was @value{GDBN} that planted the
38032breakpoint or the breakpoint is hardcoded in the program. The @var{r}
38033part must be left empty.
38034
38035On some architectures, such as x86, at the architecture level, when a
38036breakpoint instruction executes the program counter points at the
38037breakpoint address plus an offset. On such targets, the stub is
38038responsible for adjusting the PC to point back at the breakpoint
38039address.
38040
38041This packet should not be sent by default; older @value{GDBN} versions
38042did not support it. @value{GDBN} requests it, by supplying an
38043appropriate @samp{qSupported} feature (@pxref{qSupported}). The
38044remote stub must also supply the appropriate @samp{qSupported} feature
38045indicating support.
38046
38047This packet is required for correct non-stop mode operation.
38048
38049@item hwbreak
38050The packet indicates the target stopped for a hardware breakpoint.
38051The @var{r} part must be left empty.
38052
38053The same remarks about @samp{qSupported} and non-stop mode above
38054apply.
0d71eef5
DB
38055
38056@cindex fork events, remote reply
38057@item fork
38058The packet indicates that @code{fork} was called, and @var{r}
38059is the thread ID of the new child process. Refer to
38060@ref{thread-id syntax} for the format of the @var{thread-id}
38061field. This packet is only applicable to targets that support
38062fork events.
38063
38064This packet should not be sent by default; older @value{GDBN} versions
38065did not support it. @value{GDBN} requests it, by supplying an
38066appropriate @samp{qSupported} feature (@pxref{qSupported}). The
38067remote stub must also supply the appropriate @samp{qSupported} feature
38068indicating support.
38069
38070@cindex vfork events, remote reply
38071@item vfork
38072The packet indicates that @code{vfork} was called, and @var{r}
38073is the thread ID of the new child process. Refer to
38074@ref{thread-id syntax} for the format of the @var{thread-id}
38075field. This packet is only applicable to targets that support
38076vfork events.
38077
38078This packet should not be sent by default; older @value{GDBN} versions
38079did not support it. @value{GDBN} requests it, by supplying an
38080appropriate @samp{qSupported} feature (@pxref{qSupported}). The
38081remote stub must also supply the appropriate @samp{qSupported} feature
38082indicating support.
38083
38084@cindex vforkdone events, remote reply
38085@item vforkdone
e68fa6f0
PA
38086The packet indicates that a child process created by a vfork
38087has either called @code{exec} or terminated, so that the
38088address spaces of the parent and child process are no longer
38089shared. The @var{r} part is ignored. This packet is only
38090applicable to targets that support vforkdone events.
0d71eef5
DB
38091
38092This packet should not be sent by default; older @value{GDBN} versions
38093did not support it. @value{GDBN} requests it, by supplying an
38094appropriate @samp{qSupported} feature (@pxref{qSupported}). The
38095remote stub must also supply the appropriate @samp{qSupported} feature
38096indicating support.
38097
b459a59b
DB
38098@cindex exec events, remote reply
38099@item exec
38100The packet indicates that @code{execve} was called, and @var{r}
38101is the absolute pathname of the file that was executed, in hex.
38102This packet is only applicable to targets that support exec events.
38103
38104This packet should not be sent by default; older @value{GDBN} versions
38105did not support it. @value{GDBN} requests it, by supplying an
38106appropriate @samp{qSupported} feature (@pxref{qSupported}). The
38107remote stub must also supply the appropriate @samp{qSupported} feature
38108indicating support.
38109
65706a29
PA
38110@cindex thread create event, remote reply
38111@anchor{thread create event}
38112@item create
38113The packet indicates that the thread was just created. The new thread
38114is stopped until @value{GDBN} sets it running with a resumption packet
38115(@pxref{vCont packet}). This packet should not be sent by default;
38116@value{GDBN} requests it with the @ref{QThreadEvents} packet. See
4435e1cc
TT
38117also the @samp{w} (@pxref{thread exit event}) remote reply below. The
38118@var{r} part is ignored.
65706a29 38119
cfa9d6d9 38120@end table
ee2d5c50 38121
b8ff78ce 38122@item W @var{AA}
b90a069a 38123@itemx W @var{AA} ; process:@var{pid}
8e04817f 38124The process exited, and @var{AA} is the exit status. This is only
ee2d5c50
AC
38125applicable to certain targets.
38126
4435e1cc
TT
38127The second form of the response, including the process ID of the
38128exited process, can be used only when @value{GDBN} has reported
38129support for multiprocess protocol extensions; see @ref{multiprocess
38130extensions}. Both @var{AA} and @var{pid} are formatted as big-endian
38131hex strings.
b90a069a 38132
b8ff78ce 38133@item X @var{AA}
b90a069a 38134@itemx X @var{AA} ; process:@var{pid}
8e04817f 38135The process terminated with signal @var{AA}.
c906108c 38136
b90a069a
SL
38137The second form of the response, including the process ID of the
38138terminated process, can be used only when @value{GDBN} has reported
38139support for multiprocess protocol extensions; see @ref{multiprocess
4435e1cc
TT
38140extensions}. Both @var{AA} and @var{pid} are formatted as big-endian
38141hex strings.
b90a069a 38142
65706a29
PA
38143@anchor{thread exit event}
38144@cindex thread exit event, remote reply
38145@item w @var{AA} ; @var{tid}
38146
38147The thread exited, and @var{AA} is the exit status. This response
38148should not be sent by default; @value{GDBN} requests it with the
38149@ref{QThreadEvents} packet. See also @ref{thread create event} above.
4435e1cc 38150@var{AA} is formatted as a big-endian hex string.
65706a29 38151
f2faf941
PA
38152@item N
38153There are no resumed threads left in the target. In other words, even
38154though the process is alive, the last resumed thread has exited. For
38155example, say the target process has two threads: thread 1 and thread
381562. The client leaves thread 1 stopped, and resumes thread 2, which
38157subsequently exits. At this point, even though the process is still
38158alive, and thus no @samp{W} stop reply is sent, no thread is actually
38159executing either. The @samp{N} stop reply thus informs the client
38160that it can stop waiting for stop replies. This packet should not be
38161sent by default; older @value{GDBN} versions did not support it.
38162@value{GDBN} requests it, by supplying an appropriate
38163@samp{qSupported} feature (@pxref{qSupported}). The remote stub must
38164also supply the appropriate @samp{qSupported} feature indicating
38165support.
38166
b8ff78ce
JB
38167@item O @var{XX}@dots{}
38168@samp{@var{XX}@dots{}} is hex encoding of @sc{ascii} data, to be
38169written as the program's console output. This can happen at any time
38170while the program is running and the debugger should continue to wait
8b23ecc4 38171for @samp{W}, @samp{T}, etc. This reply is not permitted in non-stop mode.
0ce1b118 38172
b8ff78ce 38173@item F @var{call-id},@var{parameter}@dots{}
0ce1b118
CV
38174@var{call-id} is the identifier which says which host system call should
38175be called. This is just the name of the function. Translation into the
38176correct system call is only applicable as it's defined in @value{GDBN}.
79a6e687 38177@xref{File-I/O Remote Protocol Extension}, for a list of implemented
0ce1b118
CV
38178system calls.
38179
b8ff78ce
JB
38180@samp{@var{parameter}@dots{}} is a list of parameters as defined for
38181this very system call.
0ce1b118 38182
b8ff78ce
JB
38183The target replies with this packet when it expects @value{GDBN} to
38184call a host system call on behalf of the target. @value{GDBN} replies
38185with an appropriate @samp{F} packet and keeps up waiting for the next
38186reply packet from the target. The latest @samp{C}, @samp{c}, @samp{S}
79a6e687
BW
38187or @samp{s} action is expected to be continued. @xref{File-I/O Remote
38188Protocol Extension}, for more details.
0ce1b118 38189
ee2d5c50
AC
38190@end table
38191
38192@node General Query Packets
38193@section General Query Packets
9c16f35a 38194@cindex remote query requests
c906108c 38195
5f3bebba
JB
38196Packets starting with @samp{q} are @dfn{general query packets};
38197packets starting with @samp{Q} are @dfn{general set packets}. General
38198query and set packets are a semi-unified form for retrieving and
38199sending information to and from the stub.
38200
38201The initial letter of a query or set packet is followed by a name
38202indicating what sort of thing the packet applies to. For example,
38203@value{GDBN} may use a @samp{qSymbol} packet to exchange symbol
38204definitions with the stub. These packet names follow some
38205conventions:
38206
38207@itemize @bullet
38208@item
38209The name must not contain commas, colons or semicolons.
38210@item
38211Most @value{GDBN} query and set packets have a leading upper case
38212letter.
38213@item
38214The names of custom vendor packets should use a company prefix, in
38215lower case, followed by a period. For example, packets designed at
38216the Acme Corporation might begin with @samp{qacme.foo} (for querying
38217foos) or @samp{Qacme.bar} (for setting bars).
38218@end itemize
38219
aa56d27a
JB
38220The name of a query or set packet should be separated from any
38221parameters by a @samp{:}; the parameters themselves should be
38222separated by @samp{,} or @samp{;}. Stubs must be careful to match the
369af7bd
DJ
38223full packet name, and check for a separator or the end of the packet,
38224in case two packet names share a common prefix. New packets should not begin
38225with @samp{qC}, @samp{qP}, or @samp{qL}@footnote{The @samp{qP} and @samp{qL}
38226packets predate these conventions, and have arguments without any terminator
38227for the packet name; we suspect they are in widespread use in places that
38228are difficult to upgrade. The @samp{qC} packet has no arguments, but some
38229existing stubs (e.g.@: RedBoot) are known to not check for the end of the
38230packet.}.
c906108c 38231
b8ff78ce
JB
38232Like the descriptions of the other packets, each description here
38233has a template showing the packet's overall syntax, followed by an
38234explanation of the packet's meaning. We include spaces in some of the
38235templates for clarity; these are not part of the packet's syntax. No
38236@value{GDBN} packet uses spaces to separate its components.
38237
5f3bebba
JB
38238Here are the currently defined query and set packets:
38239
b8ff78ce 38240@table @samp
c906108c 38241
d1feda86 38242@item QAgent:1
af4238e5 38243@itemx QAgent:0
d1feda86
YQ
38244Turn on or off the agent as a helper to perform some debugging operations
38245delegated from @value{GDBN} (@pxref{Control Agent}).
38246
d914c394
SS
38247@item QAllow:@var{op}:@var{val}@dots{}
38248@cindex @samp{QAllow} packet
38249Specify which operations @value{GDBN} expects to request of the
38250target, as a semicolon-separated list of operation name and value
38251pairs. Possible values for @var{op} include @samp{WriteReg},
38252@samp{WriteMem}, @samp{InsertBreak}, @samp{InsertTrace},
38253@samp{InsertFastTrace}, and @samp{Stop}. @var{val} is either 0,
38254indicating that @value{GDBN} will not request the operation, or 1,
38255indicating that it may. (The target can then use this to set up its
38256own internals optimally, for instance if the debugger never expects to
38257insert breakpoints, it may not need to install its own trap handler.)
38258
b8ff78ce 38259@item qC
9c16f35a 38260@cindex current thread, remote request
b8ff78ce 38261@cindex @samp{qC} packet
b90a069a 38262Return the current thread ID.
ee2d5c50
AC
38263
38264Reply:
38265@table @samp
b90a069a
SL
38266@item QC @var{thread-id}
38267Where @var{thread-id} is a thread ID as documented in
38268@ref{thread-id syntax}.
b8ff78ce 38269@item @r{(anything else)}
b90a069a 38270Any other reply implies the old thread ID.
ee2d5c50
AC
38271@end table
38272
b8ff78ce 38273@item qCRC:@var{addr},@var{length}
ff2587ec 38274@cindex CRC of memory block, remote request
b8ff78ce 38275@cindex @samp{qCRC} packet
936d2992 38276@anchor{qCRC packet}
99e008fe
EZ
38277Compute the CRC checksum of a block of memory using CRC-32 defined in
38278IEEE 802.3. The CRC is computed byte at a time, taking the most
38279significant bit of each byte first. The initial pattern code
38280@code{0xffffffff} is used to ensure leading zeros affect the CRC.
38281
38282@emph{Note:} This is the same CRC used in validating separate debug
38283files (@pxref{Separate Debug Files, , Debugging Information in Separate
38284Files}). However the algorithm is slightly different. When validating
38285separate debug files, the CRC is computed taking the @emph{least}
38286significant bit of each byte first, and the final result is inverted to
38287detect trailing zeros.
38288
ff2587ec
WZ
38289Reply:
38290@table @samp
b8ff78ce 38291@item E @var{NN}
ff2587ec 38292An error (such as memory fault)
b8ff78ce
JB
38293@item C @var{crc32}
38294The specified memory region's checksum is @var{crc32}.
ff2587ec
WZ
38295@end table
38296
03583c20
UW
38297@item QDisableRandomization:@var{value}
38298@cindex disable address space randomization, remote request
38299@cindex @samp{QDisableRandomization} packet
38300Some target operating systems will randomize the virtual address space
38301of the inferior process as a security feature, but provide a feature
38302to disable such randomization, e.g.@: to allow for a more deterministic
38303debugging experience. On such systems, this packet with a @var{value}
38304of 1 directs the target to disable address space randomization for
38305processes subsequently started via @samp{vRun} packets, while a packet
38306with a @var{value} of 0 tells the target to enable address space
38307randomization.
38308
38309This packet is only available in extended mode (@pxref{extended mode}).
38310
38311Reply:
38312@table @samp
38313@item OK
38314The request succeeded.
38315
38316@item E @var{nn}
697aa1b7 38317An error occurred. The error number @var{nn} is given as hex digits.
03583c20 38318
d57350ea 38319@item @w{}
03583c20
UW
38320An empty reply indicates that @samp{QDisableRandomization} is not supported
38321by the stub.
38322@end table
38323
38324This packet is not probed by default; the remote stub must request it,
38325by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
38326This should only be done on targets that actually support disabling
38327address space randomization.
38328
aefd8b33
SDJ
38329@item QStartupWithShell:@var{value}
38330@cindex startup with shell, remote request
38331@cindex @samp{QStartupWithShell} packet
38332On UNIX-like targets, it is possible to start the inferior using a
38333shell program. This is the default behavior on both @value{GDBN} and
38334@command{gdbserver} (@pxref{set startup-with-shell}). This packet is
38335used to inform @command{gdbserver} whether it should start the
38336inferior using a shell or not.
38337
38338If @var{value} is @samp{0}, @command{gdbserver} will not use a shell
38339to start the inferior. If @var{value} is @samp{1},
38340@command{gdbserver} will use a shell to start the inferior. All other
38341values are considered an error.
38342
38343This packet is only available in extended mode (@pxref{extended
38344mode}).
38345
38346Reply:
38347@table @samp
38348@item OK
38349The request succeeded.
38350
38351@item E @var{nn}
38352An error occurred. The error number @var{nn} is given as hex digits.
38353@end table
38354
38355This packet is not probed by default; the remote stub must request it,
38356by supplying an appropriate @samp{qSupported} response
38357(@pxref{qSupported}). This should only be done on targets that
38358actually support starting the inferior using a shell.
38359
38360Use of this packet is controlled by the @code{set startup-with-shell}
38361command; @pxref{set startup-with-shell}.
38362
0a2dde4a
SDJ
38363@item QEnvironmentHexEncoded:@var{hex-value}
38364@anchor{QEnvironmentHexEncoded}
38365@cindex set environment variable, remote request
38366@cindex @samp{QEnvironmentHexEncoded} packet
38367On UNIX-like targets, it is possible to set environment variables that
38368will be passed to the inferior during the startup process. This
38369packet is used to inform @command{gdbserver} of an environment
38370variable that has been defined by the user on @value{GDBN} (@pxref{set
38371environment}).
38372
38373The packet is composed by @var{hex-value}, an hex encoded
38374representation of the @var{name=value} format representing an
38375environment variable. The name of the environment variable is
38376represented by @var{name}, and the value to be assigned to the
38377environment variable is represented by @var{value}. If the variable
38378has no value (i.e., the value is @code{null}), then @var{value} will
38379not be present.
38380
38381This packet is only available in extended mode (@pxref{extended
38382mode}).
38383
38384Reply:
38385@table @samp
38386@item OK
38387The request succeeded.
38388@end table
38389
38390This packet is not probed by default; the remote stub must request it,
38391by supplying an appropriate @samp{qSupported} response
38392(@pxref{qSupported}). This should only be done on targets that
38393actually support passing environment variables to the starting
38394inferior.
38395
38396This packet is related to the @code{set environment} command;
38397@pxref{set environment}.
38398
38399@item QEnvironmentUnset:@var{hex-value}
38400@anchor{QEnvironmentUnset}
38401@cindex unset environment variable, remote request
38402@cindex @samp{QEnvironmentUnset} packet
38403On UNIX-like targets, it is possible to unset environment variables
38404before starting the inferior in the remote target. This packet is
38405used to inform @command{gdbserver} of an environment variable that has
38406been unset by the user on @value{GDBN} (@pxref{unset environment}).
38407
38408The packet is composed by @var{hex-value}, an hex encoded
38409representation of the name of the environment variable to be unset.
38410
38411This packet is only available in extended mode (@pxref{extended
38412mode}).
38413
38414Reply:
38415@table @samp
38416@item OK
38417The request succeeded.
38418@end table
38419
38420This packet is not probed by default; the remote stub must request it,
38421by supplying an appropriate @samp{qSupported} response
38422(@pxref{qSupported}). This should only be done on targets that
38423actually support passing environment variables to the starting
38424inferior.
38425
38426This packet is related to the @code{unset environment} command;
38427@pxref{unset environment}.
38428
38429@item QEnvironmentReset
38430@anchor{QEnvironmentReset}
38431@cindex reset environment, remote request
38432@cindex @samp{QEnvironmentReset} packet
38433On UNIX-like targets, this packet is used to reset the state of
38434environment variables in the remote target before starting the
38435inferior. In this context, reset means unsetting all environment
38436variables that were previously set by the user (i.e., were not
38437initially present in the environment). It is sent to
38438@command{gdbserver} before the @samp{QEnvironmentHexEncoded}
38439(@pxref{QEnvironmentHexEncoded}) and the @samp{QEnvironmentUnset}
38440(@pxref{QEnvironmentUnset}) packets.
38441
38442This packet is only available in extended mode (@pxref{extended
38443mode}).
38444
38445Reply:
38446@table @samp
38447@item OK
38448The request succeeded.
38449@end table
38450
38451This packet is not probed by default; the remote stub must request it,
38452by supplying an appropriate @samp{qSupported} response
38453(@pxref{qSupported}). This should only be done on targets that
38454actually support passing environment variables to the starting
38455inferior.
38456
bc3b087d
SDJ
38457@item QSetWorkingDir:@r{[}@var{directory}@r{]}
38458@anchor{QSetWorkingDir packet}
38459@cindex set working directory, remote request
38460@cindex @samp{QSetWorkingDir} packet
38461This packet is used to inform the remote server of the intended
38462current working directory for programs that are going to be executed.
38463
38464The packet is composed by @var{directory}, an hex encoded
38465representation of the directory that the remote inferior will use as
38466its current working directory. If @var{directory} is an empty string,
38467the remote server should reset the inferior's current working
38468directory to its original, empty value.
38469
38470This packet is only available in extended mode (@pxref{extended
38471mode}).
38472
38473Reply:
38474@table @samp
38475@item OK
38476The request succeeded.
38477@end table
38478
b8ff78ce
JB
38479@item qfThreadInfo
38480@itemx qsThreadInfo
9c16f35a 38481@cindex list active threads, remote request
b8ff78ce
JB
38482@cindex @samp{qfThreadInfo} packet
38483@cindex @samp{qsThreadInfo} packet
b90a069a 38484Obtain a list of all active thread IDs from the target (OS). Since there
8e04817f
AC
38485may be too many active threads to fit into one reply packet, this query
38486works iteratively: it may require more than one query/reply sequence to
38487obtain the entire list of threads. The first query of the sequence will
b8ff78ce
JB
38488be the @samp{qfThreadInfo} query; subsequent queries in the
38489sequence will be the @samp{qsThreadInfo} query.
ee2d5c50 38490
b8ff78ce 38491NOTE: This packet replaces the @samp{qL} query (see below).
ee2d5c50
AC
38492
38493Reply:
38494@table @samp
b90a069a
SL
38495@item m @var{thread-id}
38496A single thread ID
38497@item m @var{thread-id},@var{thread-id}@dots{}
38498a comma-separated list of thread IDs
b8ff78ce
JB
38499@item l
38500(lower case letter @samp{L}) denotes end of list.
ee2d5c50
AC
38501@end table
38502
38503In response to each query, the target will reply with a list of one or
b90a069a 38504more thread IDs, separated by commas.
e1aac25b 38505@value{GDBN} will respond to each reply with a request for more thread
b8ff78ce 38506ids (using the @samp{qs} form of the query), until the target responds
501994c0 38507with @samp{l} (lower-case ell, for @dfn{last}).
b90a069a
SL
38508Refer to @ref{thread-id syntax}, for the format of the @var{thread-id}
38509fields.
c906108c 38510
8dfcab11
DT
38511@emph{Note: @value{GDBN} will send the @code{qfThreadInfo} query during the
38512initial connection with the remote target, and the very first thread ID
38513mentioned in the reply will be stopped by @value{GDBN} in a subsequent
38514message. Therefore, the stub should ensure that the first thread ID in
38515the @code{qfThreadInfo} reply is suitable for being stopped by @value{GDBN}.}
38516
b8ff78ce 38517@item qGetTLSAddr:@var{thread-id},@var{offset},@var{lm}
ff2587ec 38518@cindex get thread-local storage address, remote request
b8ff78ce 38519@cindex @samp{qGetTLSAddr} packet
ff2587ec
WZ
38520Fetch the address associated with thread local storage specified
38521by @var{thread-id}, @var{offset}, and @var{lm}.
38522
b90a069a
SL
38523@var{thread-id} is the thread ID associated with the
38524thread for which to fetch the TLS address. @xref{thread-id syntax}.
ff2587ec
WZ
38525
38526@var{offset} is the (big endian, hex encoded) offset associated with the
38527thread local variable. (This offset is obtained from the debug
38528information associated with the variable.)
38529
db2e3e2e 38530@var{lm} is the (big endian, hex encoded) OS/ABI-specific encoding of the
7a9dd1b2 38531load module associated with the thread local storage. For example,
ff2587ec
WZ
38532a @sc{gnu}/Linux system will pass the link map address of the shared
38533object associated with the thread local storage under consideration.
38534Other operating environments may choose to represent the load module
38535differently, so the precise meaning of this parameter will vary.
ee2d5c50
AC
38536
38537Reply:
b8ff78ce
JB
38538@table @samp
38539@item @var{XX}@dots{}
ff2587ec
WZ
38540Hex encoded (big endian) bytes representing the address of the thread
38541local storage requested.
38542
b8ff78ce 38543@item E @var{nn}
697aa1b7 38544An error occurred. The error number @var{nn} is given as hex digits.
ff2587ec 38545
d57350ea 38546@item @w{}
b8ff78ce 38547An empty reply indicates that @samp{qGetTLSAddr} is not supported by the stub.
ee2d5c50
AC
38548@end table
38549
711e434b
PM
38550@item qGetTIBAddr:@var{thread-id}
38551@cindex get thread information block address
38552@cindex @samp{qGetTIBAddr} packet
38553Fetch address of the Windows OS specific Thread Information Block.
38554
38555@var{thread-id} is the thread ID associated with the thread.
38556
38557Reply:
38558@table @samp
38559@item @var{XX}@dots{}
38560Hex encoded (big endian) bytes representing the linear address of the
38561thread information block.
38562
38563@item E @var{nn}
38564An error occured. This means that either the thread was not found, or the
38565address could not be retrieved.
38566
d57350ea 38567@item @w{}
711e434b
PM
38568An empty reply indicates that @samp{qGetTIBAddr} is not supported by the stub.
38569@end table
38570
b8ff78ce 38571@item qL @var{startflag} @var{threadcount} @var{nextthread}
8e04817f
AC
38572Obtain thread information from RTOS. Where: @var{startflag} (one hex
38573digit) is one to indicate the first query and zero to indicate a
38574subsequent query; @var{threadcount} (two hex digits) is the maximum
38575number of threads the response packet can contain; and @var{nextthread}
38576(eight hex digits), for subsequent queries (@var{startflag} is zero), is
38577returned in the response as @var{argthread}.
ee2d5c50 38578
b8ff78ce 38579Don't use this packet; use the @samp{qfThreadInfo} query instead (see above).
ee2d5c50
AC
38580
38581Reply:
38582@table @samp
b8ff78ce 38583@item qM @var{count} @var{done} @var{argthread} @var{thread}@dots{}
8e04817f
AC
38584Where: @var{count} (two hex digits) is the number of threads being
38585returned; @var{done} (one hex digit) is zero to indicate more threads
38586and one indicates no further threads; @var{argthreadid} (eight hex
b8ff78ce 38587digits) is @var{nextthread} from the request packet; @var{thread}@dots{}
697aa1b7
EZ
38588is a sequence of thread IDs, @var{threadid} (eight hex
38589digits), from the target. See @code{remote.c:parse_threadlist_response()}.
ee2d5c50 38590@end table
c906108c 38591
b8ff78ce 38592@item qOffsets
9c16f35a 38593@cindex section offsets, remote request
b8ff78ce 38594@cindex @samp{qOffsets} packet
31d99776
DJ
38595Get section offsets that the target used when relocating the downloaded
38596image.
c906108c 38597
ee2d5c50
AC
38598Reply:
38599@table @samp
31d99776
DJ
38600@item Text=@var{xxx};Data=@var{yyy}@r{[};Bss=@var{zzz}@r{]}
38601Relocate the @code{Text} section by @var{xxx} from its original address.
38602Relocate the @code{Data} section by @var{yyy} from its original address.
38603If the object file format provides segment information (e.g.@: @sc{elf}
38604@samp{PT_LOAD} program headers), @value{GDBN} will relocate entire
38605segments by the supplied offsets.
38606
38607@emph{Note: while a @code{Bss} offset may be included in the response,
38608@value{GDBN} ignores this and instead applies the @code{Data} offset
38609to the @code{Bss} section.}
38610
38611@item TextSeg=@var{xxx}@r{[};DataSeg=@var{yyy}@r{]}
38612Relocate the first segment of the object file, which conventionally
38613contains program code, to a starting address of @var{xxx}. If
38614@samp{DataSeg} is specified, relocate the second segment, which
38615conventionally contains modifiable data, to a starting address of
38616@var{yyy}. @value{GDBN} will report an error if the object file
38617does not contain segment information, or does not contain at least
38618as many segments as mentioned in the reply. Extra segments are
38619kept at fixed offsets relative to the last relocated segment.
ee2d5c50
AC
38620@end table
38621
b90a069a 38622@item qP @var{mode} @var{thread-id}
9c16f35a 38623@cindex thread information, remote request
b8ff78ce 38624@cindex @samp{qP} packet
b90a069a
SL
38625Returns information on @var{thread-id}. Where: @var{mode} is a hex
38626encoded 32 bit mode; @var{thread-id} is a thread ID
38627(@pxref{thread-id syntax}).
ee2d5c50 38628
aa56d27a
JB
38629Don't use this packet; use the @samp{qThreadExtraInfo} query instead
38630(see below).
38631
b8ff78ce 38632Reply: see @code{remote.c:remote_unpack_thread_info_response()}.
c906108c 38633
8b23ecc4 38634@item QNonStop:1
687e43a4 38635@itemx QNonStop:0
8b23ecc4
SL
38636@cindex non-stop mode, remote request
38637@cindex @samp{QNonStop} packet
38638@anchor{QNonStop}
38639Enter non-stop (@samp{QNonStop:1}) or all-stop (@samp{QNonStop:0}) mode.
38640@xref{Remote Non-Stop}, for more information.
38641
38642Reply:
38643@table @samp
38644@item OK
38645The request succeeded.
38646
38647@item E @var{nn}
697aa1b7 38648An error occurred. The error number @var{nn} is given as hex digits.
8b23ecc4 38649
d57350ea 38650@item @w{}
8b23ecc4
SL
38651An empty reply indicates that @samp{QNonStop} is not supported by
38652the stub.
38653@end table
38654
38655This packet is not probed by default; the remote stub must request it,
38656by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
38657Use of this packet is controlled by the @code{set non-stop} command;
38658@pxref{Non-Stop Mode}.
38659
82075af2
JS
38660@item QCatchSyscalls:1 @r{[};@var{sysno}@r{]}@dots{}
38661@itemx QCatchSyscalls:0
38662@cindex catch syscalls from inferior, remote request
38663@cindex @samp{QCatchSyscalls} packet
38664@anchor{QCatchSyscalls}
38665Enable (@samp{QCatchSyscalls:1}) or disable (@samp{QCatchSyscalls:0})
38666catching syscalls from the inferior process.
38667
38668For @samp{QCatchSyscalls:1}, each listed syscall @var{sysno} (encoded
38669in hex) should be reported to @value{GDBN}. If no syscall @var{sysno}
38670is listed, every system call should be reported.
38671
38672Note that if a syscall not in the list is reported, @value{GDBN} will
38673still filter the event according to its own list from all corresponding
38674@code{catch syscall} commands. However, it is more efficient to only
38675report the requested syscalls.
38676
38677Multiple @samp{QCatchSyscalls:1} packets do not combine; any earlier
38678@samp{QCatchSyscalls:1} list is completely replaced by the new list.
38679
38680If the inferior process execs, the state of @samp{QCatchSyscalls} is
38681kept for the new process too. On targets where exec may affect syscall
38682numbers, for example with exec between 32 and 64-bit processes, the
38683client should send a new packet with the new syscall list.
38684
38685Reply:
38686@table @samp
38687@item OK
38688The request succeeded.
38689
38690@item E @var{nn}
38691An error occurred. @var{nn} are hex digits.
38692
38693@item @w{}
38694An empty reply indicates that @samp{QCatchSyscalls} is not supported by
38695the stub.
38696@end table
38697
38698Use of this packet is controlled by the @code{set remote catch-syscalls}
38699command (@pxref{Remote Configuration, set remote catch-syscalls}).
38700This packet is not probed by default; the remote stub must request it,
38701by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
38702
89be2091
DJ
38703@item QPassSignals: @var{signal} @r{[};@var{signal}@r{]}@dots{}
38704@cindex pass signals to inferior, remote request
38705@cindex @samp{QPassSignals} packet
23181151 38706@anchor{QPassSignals}
89be2091
DJ
38707Each listed @var{signal} should be passed directly to the inferior process.
38708Signals are numbered identically to continue packets and stop replies
38709(@pxref{Stop Reply Packets}). Each @var{signal} list item should be
38710strictly greater than the previous item. These signals do not need to stop
38711the inferior, or be reported to @value{GDBN}. All other signals should be
38712reported to @value{GDBN}. Multiple @samp{QPassSignals} packets do not
38713combine; any earlier @samp{QPassSignals} list is completely replaced by the
38714new list. This packet improves performance when using @samp{handle
38715@var{signal} nostop noprint pass}.
38716
38717Reply:
38718@table @samp
38719@item OK
38720The request succeeded.
38721
38722@item E @var{nn}
697aa1b7 38723An error occurred. The error number @var{nn} is given as hex digits.
89be2091 38724
d57350ea 38725@item @w{}
89be2091
DJ
38726An empty reply indicates that @samp{QPassSignals} is not supported by
38727the stub.
38728@end table
38729
38730Use of this packet is controlled by the @code{set remote pass-signals}
79a6e687 38731command (@pxref{Remote Configuration, set remote pass-signals}).
89be2091
DJ
38732This packet is not probed by default; the remote stub must request it,
38733by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
38734
9b224c5e
PA
38735@item QProgramSignals: @var{signal} @r{[};@var{signal}@r{]}@dots{}
38736@cindex signals the inferior may see, remote request
38737@cindex @samp{QProgramSignals} packet
38738@anchor{QProgramSignals}
38739Each listed @var{signal} may be delivered to the inferior process.
38740Others should be silently discarded.
38741
38742In some cases, the remote stub may need to decide whether to deliver a
38743signal to the program or not without @value{GDBN} involvement. One
38744example of that is while detaching --- the program's threads may have
38745stopped for signals that haven't yet had a chance of being reported to
38746@value{GDBN}, and so the remote stub can use the signal list specified
38747by this packet to know whether to deliver or ignore those pending
38748signals.
38749
38750This does not influence whether to deliver a signal as requested by a
38751resumption packet (@pxref{vCont packet}).
38752
38753Signals are numbered identically to continue packets and stop replies
38754(@pxref{Stop Reply Packets}). Each @var{signal} list item should be
38755strictly greater than the previous item. Multiple
38756@samp{QProgramSignals} packets do not combine; any earlier
38757@samp{QProgramSignals} list is completely replaced by the new list.
38758
38759Reply:
38760@table @samp
38761@item OK
38762The request succeeded.
38763
38764@item E @var{nn}
697aa1b7 38765An error occurred. The error number @var{nn} is given as hex digits.
9b224c5e 38766
d57350ea 38767@item @w{}
9b224c5e
PA
38768An empty reply indicates that @samp{QProgramSignals} is not supported
38769by the stub.
38770@end table
38771
38772Use of this packet is controlled by the @code{set remote program-signals}
38773command (@pxref{Remote Configuration, set remote program-signals}).
38774This packet is not probed by default; the remote stub must request it,
38775by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
38776
65706a29
PA
38777@anchor{QThreadEvents}
38778@item QThreadEvents:1
38779@itemx QThreadEvents:0
38780@cindex thread create/exit events, remote request
38781@cindex @samp{QThreadEvents} packet
38782
38783Enable (@samp{QThreadEvents:1}) or disable (@samp{QThreadEvents:0})
38784reporting of thread create and exit events. @xref{thread create
38785event}, for the reply specifications. For example, this is used in
38786non-stop mode when @value{GDBN} stops a set of threads and
38787synchronously waits for the their corresponding stop replies. Without
38788exit events, if one of the threads exits, @value{GDBN} would hang
38789forever not knowing that it should no longer expect a stop for that
38790same thread. @value{GDBN} does not enable this feature unless the
38791stub reports that it supports it by including @samp{QThreadEvents+} in
38792its @samp{qSupported} reply.
38793
38794Reply:
38795@table @samp
38796@item OK
38797The request succeeded.
38798
38799@item E @var{nn}
38800An error occurred. The error number @var{nn} is given as hex digits.
38801
38802@item @w{}
38803An empty reply indicates that @samp{QThreadEvents} is not supported by
38804the stub.
38805@end table
38806
38807Use of this packet is controlled by the @code{set remote thread-events}
38808command (@pxref{Remote Configuration, set remote thread-events}).
38809
b8ff78ce 38810@item qRcmd,@var{command}
ff2587ec 38811@cindex execute remote command, remote request
b8ff78ce 38812@cindex @samp{qRcmd} packet
ff2587ec 38813@var{command} (hex encoded) is passed to the local interpreter for
b8ff78ce
JB
38814execution. Invalid commands should be reported using the output
38815string. Before the final result packet, the target may also respond
38816with a number of intermediate @samp{O@var{output}} console output
38817packets. @emph{Implementors should note that providing access to a
38818stubs's interpreter may have security implications}.
fa93a9d8 38819
ff2587ec
WZ
38820Reply:
38821@table @samp
38822@item OK
38823A command response with no output.
38824@item @var{OUTPUT}
38825A command response with the hex encoded output string @var{OUTPUT}.
b8ff78ce 38826@item E @var{NN}
ff2587ec 38827Indicate a badly formed request.
d57350ea 38828@item @w{}
b8ff78ce 38829An empty reply indicates that @samp{qRcmd} is not recognized.
ff2587ec 38830@end table
fa93a9d8 38831
aa56d27a
JB
38832(Note that the @code{qRcmd} packet's name is separated from the
38833command by a @samp{,}, not a @samp{:}, contrary to the naming
38834conventions above. Please don't use this packet as a model for new
38835packets.)
38836
08388c79
DE
38837@item qSearch:memory:@var{address};@var{length};@var{search-pattern}
38838@cindex searching memory, in remote debugging
5c4808ca 38839@ifnotinfo
08388c79 38840@cindex @samp{qSearch:memory} packet
5c4808ca
EZ
38841@end ifnotinfo
38842@cindex @samp{qSearch memory} packet
08388c79
DE
38843@anchor{qSearch memory}
38844Search @var{length} bytes at @var{address} for @var{search-pattern}.
697aa1b7
EZ
38845Both @var{address} and @var{length} are encoded in hex;
38846@var{search-pattern} is a sequence of bytes, also hex encoded.
08388c79
DE
38847
38848Reply:
38849@table @samp
38850@item 0
38851The pattern was not found.
38852@item 1,address
38853The pattern was found at @var{address}.
38854@item E @var{NN}
38855A badly formed request or an error was encountered while searching memory.
d57350ea 38856@item @w{}
08388c79
DE
38857An empty reply indicates that @samp{qSearch:memory} is not recognized.
38858@end table
38859
a6f3e723
SL
38860@item QStartNoAckMode
38861@cindex @samp{QStartNoAckMode} packet
38862@anchor{QStartNoAckMode}
38863Request that the remote stub disable the normal @samp{+}/@samp{-}
38864protocol acknowledgments (@pxref{Packet Acknowledgment}).
38865
38866Reply:
38867@table @samp
38868@item OK
38869The stub has switched to no-acknowledgment mode.
38870@value{GDBN} acknowledges this reponse,
38871but neither the stub nor @value{GDBN} shall send or expect further
38872@samp{+}/@samp{-} acknowledgments in the current connection.
d57350ea 38873@item @w{}
a6f3e723
SL
38874An empty reply indicates that the stub does not support no-acknowledgment mode.
38875@end table
38876
be2a5f71
DJ
38877@item qSupported @r{[}:@var{gdbfeature} @r{[};@var{gdbfeature}@r{]}@dots{} @r{]}
38878@cindex supported packets, remote query
38879@cindex features of the remote protocol
38880@cindex @samp{qSupported} packet
0876f84a 38881@anchor{qSupported}
be2a5f71
DJ
38882Tell the remote stub about features supported by @value{GDBN}, and
38883query the stub for features it supports. This packet allows
38884@value{GDBN} and the remote stub to take advantage of each others'
38885features. @samp{qSupported} also consolidates multiple feature probes
38886at startup, to improve @value{GDBN} performance---a single larger
38887packet performs better than multiple smaller probe packets on
38888high-latency links. Some features may enable behavior which must not
38889be on by default, e.g.@: because it would confuse older clients or
38890stubs. Other features may describe packets which could be
38891automatically probed for, but are not. These features must be
38892reported before @value{GDBN} will use them. This ``default
38893unsupported'' behavior is not appropriate for all packets, but it
38894helps to keep the initial connection time under control with new
38895versions of @value{GDBN} which support increasing numbers of packets.
38896
38897Reply:
38898@table @samp
38899@item @var{stubfeature} @r{[};@var{stubfeature}@r{]}@dots{}
38900The stub supports or does not support each returned @var{stubfeature},
38901depending on the form of each @var{stubfeature} (see below for the
38902possible forms).
d57350ea 38903@item @w{}
be2a5f71
DJ
38904An empty reply indicates that @samp{qSupported} is not recognized,
38905or that no features needed to be reported to @value{GDBN}.
38906@end table
38907
38908The allowed forms for each feature (either a @var{gdbfeature} in the
38909@samp{qSupported} packet, or a @var{stubfeature} in the response)
38910are:
38911
38912@table @samp
38913@item @var{name}=@var{value}
38914The remote protocol feature @var{name} is supported, and associated
38915with the specified @var{value}. The format of @var{value} depends
38916on the feature, but it must not include a semicolon.
38917@item @var{name}+
38918The remote protocol feature @var{name} is supported, and does not
38919need an associated value.
38920@item @var{name}-
38921The remote protocol feature @var{name} is not supported.
38922@item @var{name}?
38923The remote protocol feature @var{name} may be supported, and
38924@value{GDBN} should auto-detect support in some other way when it is
38925needed. This form will not be used for @var{gdbfeature} notifications,
38926but may be used for @var{stubfeature} responses.
38927@end table
38928
38929Whenever the stub receives a @samp{qSupported} request, the
38930supplied set of @value{GDBN} features should override any previous
38931request. This allows @value{GDBN} to put the stub in a known
38932state, even if the stub had previously been communicating with
38933a different version of @value{GDBN}.
38934
b90a069a
SL
38935The following values of @var{gdbfeature} (for the packet sent by @value{GDBN})
38936are defined:
38937
38938@table @samp
38939@item multiprocess
38940This feature indicates whether @value{GDBN} supports multiprocess
38941extensions to the remote protocol. @value{GDBN} does not use such
38942extensions unless the stub also reports that it supports them by
38943including @samp{multiprocess+} in its @samp{qSupported} reply.
38944@xref{multiprocess extensions}, for details.
c8d5aac9
L
38945
38946@item xmlRegisters
38947This feature indicates that @value{GDBN} supports the XML target
38948description. If the stub sees @samp{xmlRegisters=} with target
38949specific strings separated by a comma, it will report register
38950description.
dde08ee1
PA
38951
38952@item qRelocInsn
38953This feature indicates whether @value{GDBN} supports the
38954@samp{qRelocInsn} packet (@pxref{Tracepoint Packets,,Relocate
38955instruction reply packet}).
f7e6eed5
PA
38956
38957@item swbreak
38958This feature indicates whether @value{GDBN} supports the swbreak stop
38959reason in stop replies. @xref{swbreak stop reason}, for details.
38960
38961@item hwbreak
38962This feature indicates whether @value{GDBN} supports the hwbreak stop
38963reason in stop replies. @xref{swbreak stop reason}, for details.
0d71eef5
DB
38964
38965@item fork-events
38966This feature indicates whether @value{GDBN} supports fork event
38967extensions to the remote protocol. @value{GDBN} does not use such
38968extensions unless the stub also reports that it supports them by
38969including @samp{fork-events+} in its @samp{qSupported} reply.
38970
38971@item vfork-events
38972This feature indicates whether @value{GDBN} supports vfork event
38973extensions to the remote protocol. @value{GDBN} does not use such
38974extensions unless the stub also reports that it supports them by
38975including @samp{vfork-events+} in its @samp{qSupported} reply.
b459a59b
DB
38976
38977@item exec-events
38978This feature indicates whether @value{GDBN} supports exec event
38979extensions to the remote protocol. @value{GDBN} does not use such
38980extensions unless the stub also reports that it supports them by
38981including @samp{exec-events+} in its @samp{qSupported} reply.
750ce8d1
YQ
38982
38983@item vContSupported
38984This feature indicates whether @value{GDBN} wants to know the
38985supported actions in the reply to @samp{vCont?} packet.
b90a069a
SL
38986@end table
38987
38988Stubs should ignore any unknown values for
be2a5f71
DJ
38989@var{gdbfeature}. Any @value{GDBN} which sends a @samp{qSupported}
38990packet supports receiving packets of unlimited length (earlier
b90a069a 38991versions of @value{GDBN} may reject overly long responses). Additional values
be2a5f71
DJ
38992for @var{gdbfeature} may be defined in the future to let the stub take
38993advantage of new features in @value{GDBN}, e.g.@: incompatible
b90a069a
SL
38994improvements in the remote protocol---the @samp{multiprocess} feature is
38995an example of such a feature. The stub's reply should be independent
be2a5f71
DJ
38996of the @var{gdbfeature} entries sent by @value{GDBN}; first @value{GDBN}
38997describes all the features it supports, and then the stub replies with
38998all the features it supports.
38999
39000Similarly, @value{GDBN} will silently ignore unrecognized stub feature
39001responses, as long as each response uses one of the standard forms.
39002
39003Some features are flags. A stub which supports a flag feature
39004should respond with a @samp{+} form response. Other features
39005require values, and the stub should respond with an @samp{=}
39006form response.
39007
39008Each feature has a default value, which @value{GDBN} will use if
39009@samp{qSupported} is not available or if the feature is not mentioned
39010in the @samp{qSupported} response. The default values are fixed; a
39011stub is free to omit any feature responses that match the defaults.
39012
39013Not all features can be probed, but for those which can, the probing
39014mechanism is useful: in some cases, a stub's internal
39015architecture may not allow the protocol layer to know some information
39016about the underlying target in advance. This is especially common in
39017stubs which may be configured for multiple targets.
39018
39019These are the currently defined stub features and their properties:
39020
cfa9d6d9 39021@multitable @columnfractions 0.35 0.2 0.12 0.2
be2a5f71
DJ
39022@c NOTE: The first row should be @headitem, but we do not yet require
39023@c a new enough version of Texinfo (4.7) to use @headitem.
0876f84a 39024@item Feature Name
be2a5f71
DJ
39025@tab Value Required
39026@tab Default
39027@tab Probe Allowed
39028
39029@item @samp{PacketSize}
39030@tab Yes
39031@tab @samp{-}
39032@tab No
39033
0876f84a
DJ
39034@item @samp{qXfer:auxv:read}
39035@tab No
39036@tab @samp{-}
39037@tab Yes
39038
2ae8c8e7
MM
39039@item @samp{qXfer:btrace:read}
39040@tab No
39041@tab @samp{-}
39042@tab Yes
39043
f4abbc16
MM
39044@item @samp{qXfer:btrace-conf:read}
39045@tab No
39046@tab @samp{-}
39047@tab Yes
39048
c78fa86a
GB
39049@item @samp{qXfer:exec-file:read}
39050@tab No
39051@tab @samp{-}
39052@tab Yes
39053
23181151
DJ
39054@item @samp{qXfer:features:read}
39055@tab No
39056@tab @samp{-}
39057@tab Yes
39058
cfa9d6d9
DJ
39059@item @samp{qXfer:libraries:read}
39060@tab No
39061@tab @samp{-}
39062@tab Yes
39063
85dc5a12
GB
39064@item @samp{qXfer:libraries-svr4:read}
39065@tab No
39066@tab @samp{-}
39067@tab Yes
39068
39069@item @samp{augmented-libraries-svr4-read}
39070@tab No
39071@tab @samp{-}
39072@tab No
39073
68437a39
DJ
39074@item @samp{qXfer:memory-map:read}
39075@tab No
39076@tab @samp{-}
39077@tab Yes
39078
0fb4aa4b
PA
39079@item @samp{qXfer:sdata:read}
39080@tab No
39081@tab @samp{-}
39082@tab Yes
39083
0e7f50da
UW
39084@item @samp{qXfer:spu:read}
39085@tab No
39086@tab @samp{-}
39087@tab Yes
39088
39089@item @samp{qXfer:spu:write}
39090@tab No
39091@tab @samp{-}
39092@tab Yes
39093
4aa995e1
PA
39094@item @samp{qXfer:siginfo:read}
39095@tab No
39096@tab @samp{-}
39097@tab Yes
39098
39099@item @samp{qXfer:siginfo:write}
39100@tab No
39101@tab @samp{-}
39102@tab Yes
39103
dc146f7c
VP
39104@item @samp{qXfer:threads:read}
39105@tab No
39106@tab @samp{-}
39107@tab Yes
39108
b3b9301e
PA
39109@item @samp{qXfer:traceframe-info:read}
39110@tab No
39111@tab @samp{-}
39112@tab Yes
39113
169081d0
TG
39114@item @samp{qXfer:uib:read}
39115@tab No
39116@tab @samp{-}
39117@tab Yes
39118
78d85199
YQ
39119@item @samp{qXfer:fdpic:read}
39120@tab No
39121@tab @samp{-}
39122@tab Yes
dc146f7c 39123
2ae8c8e7
MM
39124@item @samp{Qbtrace:off}
39125@tab Yes
39126@tab @samp{-}
39127@tab Yes
39128
39129@item @samp{Qbtrace:bts}
39130@tab Yes
39131@tab @samp{-}
39132@tab Yes
39133
b20a6524
MM
39134@item @samp{Qbtrace:pt}
39135@tab Yes
39136@tab @samp{-}
39137@tab Yes
39138
d33501a5
MM
39139@item @samp{Qbtrace-conf:bts:size}
39140@tab Yes
39141@tab @samp{-}
39142@tab Yes
39143
b20a6524
MM
39144@item @samp{Qbtrace-conf:pt:size}
39145@tab Yes
39146@tab @samp{-}
39147@tab Yes
39148
8b23ecc4
SL
39149@item @samp{QNonStop}
39150@tab No
39151@tab @samp{-}
39152@tab Yes
39153
82075af2
JS
39154@item @samp{QCatchSyscalls}
39155@tab No
39156@tab @samp{-}
39157@tab Yes
39158
89be2091
DJ
39159@item @samp{QPassSignals}
39160@tab No
39161@tab @samp{-}
39162@tab Yes
39163
a6f3e723
SL
39164@item @samp{QStartNoAckMode}
39165@tab No
39166@tab @samp{-}
39167@tab Yes
39168
b90a069a
SL
39169@item @samp{multiprocess}
39170@tab No
39171@tab @samp{-}
39172@tab No
39173
83364271
LM
39174@item @samp{ConditionalBreakpoints}
39175@tab No
39176@tab @samp{-}
39177@tab No
39178
782b2b07
SS
39179@item @samp{ConditionalTracepoints}
39180@tab No
39181@tab @samp{-}
39182@tab No
39183
0d772ac9
MS
39184@item @samp{ReverseContinue}
39185@tab No
2f8132f3 39186@tab @samp{-}
0d772ac9
MS
39187@tab No
39188
39189@item @samp{ReverseStep}
39190@tab No
2f8132f3 39191@tab @samp{-}
0d772ac9
MS
39192@tab No
39193
409873ef
SS
39194@item @samp{TracepointSource}
39195@tab No
39196@tab @samp{-}
39197@tab No
39198
d1feda86
YQ
39199@item @samp{QAgent}
39200@tab No
39201@tab @samp{-}
39202@tab No
39203
d914c394
SS
39204@item @samp{QAllow}
39205@tab No
39206@tab @samp{-}
39207@tab No
39208
03583c20
UW
39209@item @samp{QDisableRandomization}
39210@tab No
39211@tab @samp{-}
39212@tab No
39213
d248b706
KY
39214@item @samp{EnableDisableTracepoints}
39215@tab No
39216@tab @samp{-}
39217@tab No
39218
f6f899bf
HAQ
39219@item @samp{QTBuffer:size}
39220@tab No
39221@tab @samp{-}
39222@tab No
39223
3065dfb6
SS
39224@item @samp{tracenz}
39225@tab No
39226@tab @samp{-}
39227@tab No
39228
d3ce09f5
SS
39229@item @samp{BreakpointCommands}
39230@tab No
39231@tab @samp{-}
39232@tab No
39233
f7e6eed5
PA
39234@item @samp{swbreak}
39235@tab No
39236@tab @samp{-}
39237@tab No
39238
39239@item @samp{hwbreak}
39240@tab No
39241@tab @samp{-}
39242@tab No
39243
0d71eef5
DB
39244@item @samp{fork-events}
39245@tab No
39246@tab @samp{-}
39247@tab No
39248
39249@item @samp{vfork-events}
39250@tab No
39251@tab @samp{-}
39252@tab No
39253
b459a59b
DB
39254@item @samp{exec-events}
39255@tab No
39256@tab @samp{-}
39257@tab No
39258
65706a29
PA
39259@item @samp{QThreadEvents}
39260@tab No
39261@tab @samp{-}
39262@tab No
39263
f2faf941
PA
39264@item @samp{no-resumed}
39265@tab No
39266@tab @samp{-}
39267@tab No
39268
be2a5f71
DJ
39269@end multitable
39270
39271These are the currently defined stub features, in more detail:
39272
39273@table @samp
39274@cindex packet size, remote protocol
39275@item PacketSize=@var{bytes}
39276The remote stub can accept packets up to at least @var{bytes} in
39277length. @value{GDBN} will send packets up to this size for bulk
39278transfers, and will never send larger packets. This is a limit on the
39279data characters in the packet, including the frame and checksum.
39280There is no trailing NUL byte in a remote protocol packet; if the stub
39281stores packets in a NUL-terminated format, it should allow an extra
39282byte in its buffer for the NUL. If this stub feature is not supported,
39283@value{GDBN} guesses based on the size of the @samp{g} packet response.
39284
0876f84a
DJ
39285@item qXfer:auxv:read
39286The remote stub understands the @samp{qXfer:auxv:read} packet
39287(@pxref{qXfer auxiliary vector read}).
39288
2ae8c8e7
MM
39289@item qXfer:btrace:read
39290The remote stub understands the @samp{qXfer:btrace:read}
39291packet (@pxref{qXfer btrace read}).
39292
f4abbc16
MM
39293@item qXfer:btrace-conf:read
39294The remote stub understands the @samp{qXfer:btrace-conf:read}
39295packet (@pxref{qXfer btrace-conf read}).
39296
c78fa86a
GB
39297@item qXfer:exec-file:read
39298The remote stub understands the @samp{qXfer:exec-file:read} packet
39299(@pxref{qXfer executable filename read}).
39300
23181151
DJ
39301@item qXfer:features:read
39302The remote stub understands the @samp{qXfer:features:read} packet
39303(@pxref{qXfer target description read}).
39304
cfa9d6d9
DJ
39305@item qXfer:libraries:read
39306The remote stub understands the @samp{qXfer:libraries:read} packet
39307(@pxref{qXfer library list read}).
39308
2268b414
JK
39309@item qXfer:libraries-svr4:read
39310The remote stub understands the @samp{qXfer:libraries-svr4:read} packet
39311(@pxref{qXfer svr4 library list read}).
39312
85dc5a12
GB
39313@item augmented-libraries-svr4-read
39314The remote stub understands the augmented form of the
39315@samp{qXfer:libraries-svr4:read} packet
39316(@pxref{qXfer svr4 library list read}).
39317
23181151
DJ
39318@item qXfer:memory-map:read
39319The remote stub understands the @samp{qXfer:memory-map:read} packet
39320(@pxref{qXfer memory map read}).
39321
0fb4aa4b
PA
39322@item qXfer:sdata:read
39323The remote stub understands the @samp{qXfer:sdata:read} packet
39324(@pxref{qXfer sdata read}).
39325
0e7f50da
UW
39326@item qXfer:spu:read
39327The remote stub understands the @samp{qXfer:spu:read} packet
39328(@pxref{qXfer spu read}).
39329
39330@item qXfer:spu:write
39331The remote stub understands the @samp{qXfer:spu:write} packet
39332(@pxref{qXfer spu write}).
39333
4aa995e1
PA
39334@item qXfer:siginfo:read
39335The remote stub understands the @samp{qXfer:siginfo:read} packet
39336(@pxref{qXfer siginfo read}).
39337
39338@item qXfer:siginfo:write
39339The remote stub understands the @samp{qXfer:siginfo:write} packet
39340(@pxref{qXfer siginfo write}).
39341
dc146f7c
VP
39342@item qXfer:threads:read
39343The remote stub understands the @samp{qXfer:threads:read} packet
39344(@pxref{qXfer threads read}).
39345
b3b9301e
PA
39346@item qXfer:traceframe-info:read
39347The remote stub understands the @samp{qXfer:traceframe-info:read}
39348packet (@pxref{qXfer traceframe info read}).
39349
169081d0
TG
39350@item qXfer:uib:read
39351The remote stub understands the @samp{qXfer:uib:read}
39352packet (@pxref{qXfer unwind info block}).
39353
78d85199
YQ
39354@item qXfer:fdpic:read
39355The remote stub understands the @samp{qXfer:fdpic:read}
39356packet (@pxref{qXfer fdpic loadmap read}).
39357
8b23ecc4
SL
39358@item QNonStop
39359The remote stub understands the @samp{QNonStop} packet
39360(@pxref{QNonStop}).
39361
82075af2
JS
39362@item QCatchSyscalls
39363The remote stub understands the @samp{QCatchSyscalls} packet
39364(@pxref{QCatchSyscalls}).
39365
23181151
DJ
39366@item QPassSignals
39367The remote stub understands the @samp{QPassSignals} packet
39368(@pxref{QPassSignals}).
39369
a6f3e723
SL
39370@item QStartNoAckMode
39371The remote stub understands the @samp{QStartNoAckMode} packet and
39372prefers to operate in no-acknowledgment mode. @xref{Packet Acknowledgment}.
39373
b90a069a
SL
39374@item multiprocess
39375@anchor{multiprocess extensions}
39376@cindex multiprocess extensions, in remote protocol
39377The remote stub understands the multiprocess extensions to the remote
39378protocol syntax. The multiprocess extensions affect the syntax of
39379thread IDs in both packets and replies (@pxref{thread-id syntax}), and
39380add process IDs to the @samp{D} packet and @samp{W} and @samp{X}
39381replies. Note that reporting this feature indicates support for the
39382syntactic extensions only, not that the stub necessarily supports
39383debugging of more than one process at a time. The stub must not use
39384multiprocess extensions in packet replies unless @value{GDBN} has also
39385indicated it supports them in its @samp{qSupported} request.
39386
07e059b5
VP
39387@item qXfer:osdata:read
39388The remote stub understands the @samp{qXfer:osdata:read} packet
39389((@pxref{qXfer osdata read}).
39390
83364271
LM
39391@item ConditionalBreakpoints
39392The target accepts and implements evaluation of conditional expressions
39393defined for breakpoints. The target will only report breakpoint triggers
39394when such conditions are true (@pxref{Conditions, ,Break Conditions}).
39395
782b2b07
SS
39396@item ConditionalTracepoints
39397The remote stub accepts and implements conditional expressions defined
39398for tracepoints (@pxref{Tracepoint Conditions}).
39399
0d772ac9
MS
39400@item ReverseContinue
39401The remote stub accepts and implements the reverse continue packet
39402(@pxref{bc}).
39403
39404@item ReverseStep
39405The remote stub accepts and implements the reverse step packet
39406(@pxref{bs}).
39407
409873ef
SS
39408@item TracepointSource
39409The remote stub understands the @samp{QTDPsrc} packet that supplies
39410the source form of tracepoint definitions.
39411
d1feda86
YQ
39412@item QAgent
39413The remote stub understands the @samp{QAgent} packet.
39414
d914c394
SS
39415@item QAllow
39416The remote stub understands the @samp{QAllow} packet.
39417
03583c20
UW
39418@item QDisableRandomization
39419The remote stub understands the @samp{QDisableRandomization} packet.
39420
0fb4aa4b
PA
39421@item StaticTracepoint
39422@cindex static tracepoints, in remote protocol
39423The remote stub supports static tracepoints.
39424
1e4d1764
YQ
39425@item InstallInTrace
39426@anchor{install tracepoint in tracing}
39427The remote stub supports installing tracepoint in tracing.
39428
d248b706
KY
39429@item EnableDisableTracepoints
39430The remote stub supports the @samp{QTEnable} (@pxref{QTEnable}) and
39431@samp{QTDisable} (@pxref{QTDisable}) packets that allow tracepoints
39432to be enabled and disabled while a trace experiment is running.
39433
f6f899bf 39434@item QTBuffer:size
28abe188 39435The remote stub supports the @samp{QTBuffer:size} (@pxref{QTBuffer-size})
f6f899bf
HAQ
39436packet that allows to change the size of the trace buffer.
39437
3065dfb6
SS
39438@item tracenz
39439@cindex string tracing, in remote protocol
39440The remote stub supports the @samp{tracenz} bytecode for collecting strings.
39441See @ref{Bytecode Descriptions} for details about the bytecode.
39442
d3ce09f5
SS
39443@item BreakpointCommands
39444@cindex breakpoint commands, in remote protocol
39445The remote stub supports running a breakpoint's command list itself,
39446rather than reporting the hit to @value{GDBN}.
39447
2ae8c8e7
MM
39448@item Qbtrace:off
39449The remote stub understands the @samp{Qbtrace:off} packet.
39450
39451@item Qbtrace:bts
39452The remote stub understands the @samp{Qbtrace:bts} packet.
39453
b20a6524
MM
39454@item Qbtrace:pt
39455The remote stub understands the @samp{Qbtrace:pt} packet.
39456
d33501a5
MM
39457@item Qbtrace-conf:bts:size
39458The remote stub understands the @samp{Qbtrace-conf:bts:size} packet.
39459
b20a6524
MM
39460@item Qbtrace-conf:pt:size
39461The remote stub understands the @samp{Qbtrace-conf:pt:size} packet.
39462
f7e6eed5
PA
39463@item swbreak
39464The remote stub reports the @samp{swbreak} stop reason for memory
39465breakpoints.
39466
39467@item hwbreak
39468The remote stub reports the @samp{hwbreak} stop reason for hardware
39469breakpoints.
39470
0d71eef5
DB
39471@item fork-events
39472The remote stub reports the @samp{fork} stop reason for fork events.
39473
39474@item vfork-events
39475The remote stub reports the @samp{vfork} stop reason for vfork events
39476and vforkdone events.
39477
b459a59b
DB
39478@item exec-events
39479The remote stub reports the @samp{exec} stop reason for exec events.
39480
750ce8d1
YQ
39481@item vContSupported
39482The remote stub reports the supported actions in the reply to
39483@samp{vCont?} packet.
39484
65706a29
PA
39485@item QThreadEvents
39486The remote stub understands the @samp{QThreadEvents} packet.
39487
f2faf941
PA
39488@item no-resumed
39489The remote stub reports the @samp{N} stop reply.
39490
be2a5f71
DJ
39491@end table
39492
b8ff78ce 39493@item qSymbol::
ff2587ec 39494@cindex symbol lookup, remote request
b8ff78ce 39495@cindex @samp{qSymbol} packet
ff2587ec
WZ
39496Notify the target that @value{GDBN} is prepared to serve symbol lookup
39497requests. Accept requests from the target for the values of symbols.
fa93a9d8
JB
39498
39499Reply:
ff2587ec 39500@table @samp
b8ff78ce 39501@item OK
ff2587ec 39502The target does not need to look up any (more) symbols.
b8ff78ce 39503@item qSymbol:@var{sym_name}
ff2587ec
WZ
39504The target requests the value of symbol @var{sym_name} (hex encoded).
39505@value{GDBN} may provide the value by using the
b8ff78ce
JB
39506@samp{qSymbol:@var{sym_value}:@var{sym_name}} message, described
39507below.
ff2587ec 39508@end table
83761cbd 39509
b8ff78ce 39510@item qSymbol:@var{sym_value}:@var{sym_name}
ff2587ec
WZ
39511Set the value of @var{sym_name} to @var{sym_value}.
39512
39513@var{sym_name} (hex encoded) is the name of a symbol whose value the
39514target has previously requested.
39515
39516@var{sym_value} (hex) is the value for symbol @var{sym_name}. If
39517@value{GDBN} cannot supply a value for @var{sym_name}, then this field
39518will be empty.
39519
39520Reply:
39521@table @samp
b8ff78ce 39522@item OK
ff2587ec 39523The target does not need to look up any (more) symbols.
b8ff78ce 39524@item qSymbol:@var{sym_name}
ff2587ec
WZ
39525The target requests the value of a new symbol @var{sym_name} (hex
39526encoded). @value{GDBN} will continue to supply the values of symbols
39527(if available), until the target ceases to request them.
fa93a9d8 39528@end table
0abb7bc7 39529
00bf0b85 39530@item qTBuffer
687e43a4
TT
39531@itemx QTBuffer
39532@itemx QTDisconnected
d5551862 39533@itemx QTDP
409873ef 39534@itemx QTDPsrc
d5551862 39535@itemx QTDV
00bf0b85
SS
39536@itemx qTfP
39537@itemx qTfV
9d29849a 39538@itemx QTFrame
405f8e94
SS
39539@itemx qTMinFTPILen
39540
9d29849a
JB
39541@xref{Tracepoint Packets}.
39542
b90a069a 39543@item qThreadExtraInfo,@var{thread-id}
ff2587ec 39544@cindex thread attributes info, remote request
b8ff78ce 39545@cindex @samp{qThreadExtraInfo} packet
697aa1b7
EZ
39546Obtain from the target OS a printable string description of thread
39547attributes for the thread @var{thread-id}; see @ref{thread-id syntax},
39548for the forms of @var{thread-id}. This
b8ff78ce
JB
39549string may contain anything that the target OS thinks is interesting
39550for @value{GDBN} to tell the user about the thread. The string is
39551displayed in @value{GDBN}'s @code{info threads} display. Some
39552examples of possible thread extra info strings are @samp{Runnable}, or
39553@samp{Blocked on Mutex}.
ff2587ec
WZ
39554
39555Reply:
39556@table @samp
b8ff78ce
JB
39557@item @var{XX}@dots{}
39558Where @samp{@var{XX}@dots{}} is a hex encoding of @sc{ascii} data,
39559comprising the printable string containing the extra information about
39560the thread's attributes.
ff2587ec 39561@end table
814e32d7 39562
aa56d27a
JB
39563(Note that the @code{qThreadExtraInfo} packet's name is separated from
39564the command by a @samp{,}, not a @samp{:}, contrary to the naming
39565conventions above. Please don't use this packet as a model for new
39566packets.)
39567
f196051f 39568@item QTNotes
687e43a4
TT
39569@itemx qTP
39570@itemx QTSave
39571@itemx qTsP
39572@itemx qTsV
d5551862 39573@itemx QTStart
9d29849a 39574@itemx QTStop
d248b706
KY
39575@itemx QTEnable
39576@itemx QTDisable
9d29849a
JB
39577@itemx QTinit
39578@itemx QTro
39579@itemx qTStatus
d5551862 39580@itemx qTV
0fb4aa4b
PA
39581@itemx qTfSTM
39582@itemx qTsSTM
39583@itemx qTSTMat
9d29849a
JB
39584@xref{Tracepoint Packets}.
39585
0876f84a
DJ
39586@item qXfer:@var{object}:read:@var{annex}:@var{offset},@var{length}
39587@cindex read special object, remote request
39588@cindex @samp{qXfer} packet
68437a39 39589@anchor{qXfer read}
0876f84a
DJ
39590Read uninterpreted bytes from the target's special data area
39591identified by the keyword @var{object}. Request @var{length} bytes
39592starting at @var{offset} bytes into the data. The content and
0e7f50da 39593encoding of @var{annex} is specific to @var{object}; it can supply
0876f84a
DJ
39594additional details about what data to access.
39595
c185ba27
EZ
39596Reply:
39597@table @samp
39598@item m @var{data}
39599Data @var{data} (@pxref{Binary Data}) has been read from the
39600target. There may be more data at a higher address (although
39601it is permitted to return @samp{m} even for the last valid
39602block of data, as long as at least one byte of data was read).
39603It is possible for @var{data} to have fewer bytes than the @var{length} in the
39604request.
39605
39606@item l @var{data}
39607Data @var{data} (@pxref{Binary Data}) has been read from the target.
39608There is no more data to be read. It is possible for @var{data} to
39609have fewer bytes than the @var{length} in the request.
39610
39611@item l
39612The @var{offset} in the request is at the end of the data.
39613There is no more data to be read.
39614
39615@item E00
39616The request was malformed, or @var{annex} was invalid.
39617
39618@item E @var{nn}
39619The offset was invalid, or there was an error encountered reading the data.
39620The @var{nn} part is a hex-encoded @code{errno} value.
39621
39622@item @w{}
39623An empty reply indicates the @var{object} string was not recognized by
39624the stub, or that the object does not support reading.
39625@end table
39626
39627Here are the specific requests of this form defined so far. All the
0876f84a 39628@samp{qXfer:@var{object}:read:@dots{}} requests use the same reply
c185ba27 39629formats, listed above.
0876f84a
DJ
39630
39631@table @samp
39632@item qXfer:auxv:read::@var{offset},@var{length}
39633@anchor{qXfer auxiliary vector read}
39634Access the target's @dfn{auxiliary vector}. @xref{OS Information,
427c3a89 39635auxiliary vector}. Note @var{annex} must be empty.
0876f84a
DJ
39636
39637This packet is not probed by default; the remote stub must request it,
89be2091 39638by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
0876f84a 39639
2ae8c8e7
MM
39640@item qXfer:btrace:read:@var{annex}:@var{offset},@var{length}
39641@anchor{qXfer btrace read}
39642
39643Return a description of the current branch trace.
39644@xref{Branch Trace Format}. The annex part of the generic @samp{qXfer}
39645packet may have one of the following values:
39646
39647@table @code
39648@item all
39649Returns all available branch trace.
39650
39651@item new
39652Returns all available branch trace if the branch trace changed since
39653the last read request.
969c39fb
MM
39654
39655@item delta
39656Returns the new branch trace since the last read request. Adds a new
39657block to the end of the trace that begins at zero and ends at the source
39658location of the first branch in the trace buffer. This extra block is
39659used to stitch traces together.
39660
39661If the trace buffer overflowed, returns an error indicating the overflow.
2ae8c8e7
MM
39662@end table
39663
39664This packet is not probed by default; the remote stub must request it
39665by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39666
f4abbc16
MM
39667@item qXfer:btrace-conf:read::@var{offset},@var{length}
39668@anchor{qXfer btrace-conf read}
39669
39670Return a description of the current branch trace configuration.
39671@xref{Branch Trace Configuration Format}.
39672
39673This packet is not probed by default; the remote stub must request it
39674by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
c78fa86a
GB
39675
39676@item qXfer:exec-file:read:@var{annex}:@var{offset},@var{length}
39677@anchor{qXfer executable filename read}
39678Return the full absolute name of the file that was executed to create
39679a process running on the remote system. The annex specifies the
39680numeric process ID of the process to query, encoded as a hexadecimal
835205d0
GB
39681number. If the annex part is empty the remote stub should return the
39682filename corresponding to the currently executing process.
c78fa86a
GB
39683
39684This packet is not probed by default; the remote stub must request it,
39685by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
f4abbc16 39686
23181151
DJ
39687@item qXfer:features:read:@var{annex}:@var{offset},@var{length}
39688@anchor{qXfer target description read}
39689Access the @dfn{target description}. @xref{Target Descriptions}. The
39690annex specifies which XML document to access. The main description is
39691always loaded from the @samp{target.xml} annex.
39692
39693This packet is not probed by default; the remote stub must request it,
39694by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39695
cfa9d6d9
DJ
39696@item qXfer:libraries:read:@var{annex}:@var{offset},@var{length}
39697@anchor{qXfer library list read}
39698Access the target's list of loaded libraries. @xref{Library List Format}.
39699The annex part of the generic @samp{qXfer} packet must be empty
39700(@pxref{qXfer read}).
39701
39702Targets which maintain a list of libraries in the program's memory do
39703not need to implement this packet; it is designed for platforms where
39704the operating system manages the list of loaded libraries.
39705
39706This packet is not probed by default; the remote stub must request it,
39707by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39708
2268b414
JK
39709@item qXfer:libraries-svr4:read:@var{annex}:@var{offset},@var{length}
39710@anchor{qXfer svr4 library list read}
39711Access the target's list of loaded libraries when the target is an SVR4
39712platform. @xref{Library List Format for SVR4 Targets}. The annex part
85dc5a12
GB
39713of the generic @samp{qXfer} packet must be empty unless the remote
39714stub indicated it supports the augmented form of this packet
39715by supplying an appropriate @samp{qSupported} response
39716(@pxref{qXfer read}, @ref{qSupported}).
2268b414
JK
39717
39718This packet is optional for better performance on SVR4 targets.
39719@value{GDBN} uses memory read packets to read the SVR4 library list otherwise.
39720
39721This packet is not probed by default; the remote stub must request it,
39722by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39723
85dc5a12
GB
39724If the remote stub indicates it supports the augmented form of this
39725packet then the annex part of the generic @samp{qXfer} packet may
39726contain a semicolon-separated list of @samp{@var{name}=@var{value}}
39727arguments. The currently supported arguments are:
39728
39729@table @code
39730@item start=@var{address}
39731A hexadecimal number specifying the address of the @samp{struct
39732link_map} to start reading the library list from. If unset or zero
39733then the first @samp{struct link_map} in the library list will be
39734chosen as the starting point.
39735
39736@item prev=@var{address}
39737A hexadecimal number specifying the address of the @samp{struct
39738link_map} immediately preceding the @samp{struct link_map}
39739specified by the @samp{start} argument. If unset or zero then
39740the remote stub will expect that no @samp{struct link_map}
39741exists prior to the starting point.
39742
39743@end table
39744
39745Arguments that are not understood by the remote stub will be silently
39746ignored.
39747
68437a39
DJ
39748@item qXfer:memory-map:read::@var{offset},@var{length}
39749@anchor{qXfer memory map read}
79a6e687 39750Access the target's @dfn{memory-map}. @xref{Memory Map Format}. The
68437a39
DJ
39751annex part of the generic @samp{qXfer} packet must be empty
39752(@pxref{qXfer read}).
39753
0e7f50da
UW
39754This packet is not probed by default; the remote stub must request it,
39755by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39756
0fb4aa4b
PA
39757@item qXfer:sdata:read::@var{offset},@var{length}
39758@anchor{qXfer sdata read}
39759
39760Read contents of the extra collected static tracepoint marker
39761information. The annex part of the generic @samp{qXfer} packet must
39762be empty (@pxref{qXfer read}). @xref{Tracepoint Actions,,Tracepoint
39763Action Lists}.
39764
39765This packet is not probed by default; the remote stub must request it,
39766by supplying an appropriate @samp{qSupported} response
39767(@pxref{qSupported}).
39768
4aa995e1
PA
39769@item qXfer:siginfo:read::@var{offset},@var{length}
39770@anchor{qXfer siginfo read}
39771Read contents of the extra signal information on the target
39772system. The annex part of the generic @samp{qXfer} packet must be
39773empty (@pxref{qXfer read}).
39774
39775This packet is not probed by default; the remote stub must request it,
39776by supplying an appropriate @samp{qSupported} response
39777(@pxref{qSupported}).
39778
0e7f50da
UW
39779@item qXfer:spu:read:@var{annex}:@var{offset},@var{length}
39780@anchor{qXfer spu read}
39781Read contents of an @code{spufs} file on the target system. The
39782annex specifies which file to read; it must be of the form
39783@file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID
39784in the target process, and @var{name} identifes the @code{spufs} file
39785in that context to be accessed.
39786
68437a39 39787This packet is not probed by default; the remote stub must request it,
07e059b5
VP
39788by supplying an appropriate @samp{qSupported} response
39789(@pxref{qSupported}).
39790
dc146f7c
VP
39791@item qXfer:threads:read::@var{offset},@var{length}
39792@anchor{qXfer threads read}
39793Access the list of threads on target. @xref{Thread List Format}. The
39794annex part of the generic @samp{qXfer} packet must be empty
39795(@pxref{qXfer read}).
39796
39797This packet is not probed by default; the remote stub must request it,
39798by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39799
b3b9301e
PA
39800@item qXfer:traceframe-info:read::@var{offset},@var{length}
39801@anchor{qXfer traceframe info read}
39802
39803Return a description of the current traceframe's contents.
39804@xref{Traceframe Info Format}. The annex part of the generic
39805@samp{qXfer} packet must be empty (@pxref{qXfer read}).
39806
39807This packet is not probed by default; the remote stub must request it,
39808by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39809
169081d0
TG
39810@item qXfer:uib:read:@var{pc}:@var{offset},@var{length}
39811@anchor{qXfer unwind info block}
39812
39813Return the unwind information block for @var{pc}. This packet is used
39814on OpenVMS/ia64 to ask the kernel unwind information.
39815
39816This packet is not probed by default.
39817
78d85199
YQ
39818@item qXfer:fdpic:read:@var{annex}:@var{offset},@var{length}
39819@anchor{qXfer fdpic loadmap read}
39820Read contents of @code{loadmap}s on the target system. The
39821annex, either @samp{exec} or @samp{interp}, specifies which @code{loadmap},
39822executable @code{loadmap} or interpreter @code{loadmap} to read.
39823
39824This packet is not probed by default; the remote stub must request it,
39825by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39826
07e059b5
VP
39827@item qXfer:osdata:read::@var{offset},@var{length}
39828@anchor{qXfer osdata read}
697aa1b7 39829Access the target's @dfn{operating system information}.
07e059b5
VP
39830@xref{Operating System Information}.
39831
68437a39
DJ
39832@end table
39833
c185ba27
EZ
39834@item qXfer:@var{object}:write:@var{annex}:@var{offset}:@var{data}@dots{}
39835@cindex write data into object, remote request
39836@anchor{qXfer write}
39837Write uninterpreted bytes into the target's special data area
39838identified by the keyword @var{object}, starting at @var{offset} bytes
39839into the data. The binary-encoded data (@pxref{Binary Data}) to be
39840written is given by @var{data}@dots{}. The content and encoding of @var{annex}
39841is specific to @var{object}; it can supply additional details about what data
39842to access.
39843
0876f84a
DJ
39844Reply:
39845@table @samp
c185ba27
EZ
39846@item @var{nn}
39847@var{nn} (hex encoded) is the number of bytes written.
39848This may be fewer bytes than supplied in the request.
0876f84a
DJ
39849
39850@item E00
39851The request was malformed, or @var{annex} was invalid.
39852
39853@item E @var{nn}
c185ba27 39854The offset was invalid, or there was an error encountered writing the data.
697aa1b7 39855The @var{nn} part is a hex-encoded @code{errno} value.
0876f84a 39856
d57350ea 39857@item @w{}
c185ba27
EZ
39858An empty reply indicates the @var{object} string was not
39859recognized by the stub, or that the object does not support writing.
0876f84a
DJ
39860@end table
39861
c185ba27 39862Here are the specific requests of this form defined so far. All the
0e7f50da 39863@samp{qXfer:@var{object}:write:@dots{}} requests use the same reply
c185ba27 39864formats, listed above.
0e7f50da
UW
39865
39866@table @samp
4aa995e1
PA
39867@item qXfer:siginfo:write::@var{offset}:@var{data}@dots{}
39868@anchor{qXfer siginfo write}
39869Write @var{data} to the extra signal information on the target system.
39870The annex part of the generic @samp{qXfer} packet must be
39871empty (@pxref{qXfer write}).
39872
39873This packet is not probed by default; the remote stub must request it,
39874by supplying an appropriate @samp{qSupported} response
39875(@pxref{qSupported}).
39876
84fcdf95 39877@item qXfer:spu:write:@var{annex}:@var{offset}:@var{data}@dots{}
0e7f50da
UW
39878@anchor{qXfer spu write}
39879Write @var{data} to an @code{spufs} file on the target system. The
39880annex specifies which file to write; it must be of the form
39881@file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID
39882in the target process, and @var{name} identifes the @code{spufs} file
39883in that context to be accessed.
39884
39885This packet is not probed by default; the remote stub must request it,
39886by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
39887@end table
0876f84a 39888
0876f84a
DJ
39889@item qXfer:@var{object}:@var{operation}:@dots{}
39890Requests of this form may be added in the future. When a stub does
39891not recognize the @var{object} keyword, or its support for
39892@var{object} does not recognize the @var{operation} keyword, the stub
39893must respond with an empty packet.
39894
0b16c5cf
PA
39895@item qAttached:@var{pid}
39896@cindex query attached, remote request
39897@cindex @samp{qAttached} packet
39898Return an indication of whether the remote server attached to an
39899existing process or created a new process. When the multiprocess
39900protocol extensions are supported (@pxref{multiprocess extensions}),
39901@var{pid} is an integer in hexadecimal format identifying the target
39902process. Otherwise, @value{GDBN} will omit the @var{pid} field and
39903the query packet will be simplified as @samp{qAttached}.
39904
39905This query is used, for example, to know whether the remote process
39906should be detached or killed when a @value{GDBN} session is ended with
39907the @code{quit} command.
39908
39909Reply:
39910@table @samp
39911@item 1
39912The remote server attached to an existing process.
39913@item 0
39914The remote server created a new process.
39915@item E @var{NN}
39916A badly formed request or an error was encountered.
39917@end table
39918
2ae8c8e7 39919@item Qbtrace:bts
b20a6524
MM
39920Enable branch tracing for the current thread using Branch Trace Store.
39921
39922Reply:
39923@table @samp
39924@item OK
39925Branch tracing has been enabled.
39926@item E.errtext
39927A badly formed request or an error was encountered.
39928@end table
39929
39930@item Qbtrace:pt
bc504a31 39931Enable branch tracing for the current thread using Intel Processor Trace.
2ae8c8e7
MM
39932
39933Reply:
39934@table @samp
39935@item OK
39936Branch tracing has been enabled.
39937@item E.errtext
39938A badly formed request or an error was encountered.
39939@end table
39940
39941@item Qbtrace:off
39942Disable branch tracing for the current thread.
39943
39944Reply:
39945@table @samp
39946@item OK
39947Branch tracing has been disabled.
39948@item E.errtext
39949A badly formed request or an error was encountered.
39950@end table
39951
d33501a5
MM
39952@item Qbtrace-conf:bts:size=@var{value}
39953Set the requested ring buffer size for new threads that use the
39954btrace recording method in bts format.
39955
39956Reply:
39957@table @samp
39958@item OK
39959The ring buffer size has been set.
39960@item E.errtext
39961A badly formed request or an error was encountered.
39962@end table
39963
b20a6524
MM
39964@item Qbtrace-conf:pt:size=@var{value}
39965Set the requested ring buffer size for new threads that use the
39966btrace recording method in pt format.
39967
39968Reply:
39969@table @samp
39970@item OK
39971The ring buffer size has been set.
39972@item E.errtext
39973A badly formed request or an error was encountered.
39974@end table
39975
ee2d5c50
AC
39976@end table
39977
a1dcb23a
DJ
39978@node Architecture-Specific Protocol Details
39979@section Architecture-Specific Protocol Details
39980
39981This section describes how the remote protocol is applied to specific
39982target architectures. Also see @ref{Standard Target Features}, for
39983details of XML target descriptions for each architecture.
39984
02b67415
MR
39985@menu
39986* ARM-Specific Protocol Details::
39987* MIPS-Specific Protocol Details::
39988@end menu
39989
39990@node ARM-Specific Protocol Details
39991@subsection @acronym{ARM}-specific Protocol Details
39992
39993@menu
39994* ARM Breakpoint Kinds::
39995@end menu
a1dcb23a 39996
02b67415
MR
39997@node ARM Breakpoint Kinds
39998@subsubsection @acronym{ARM} Breakpoint Kinds
39999@cindex breakpoint kinds, @acronym{ARM}
a1dcb23a
DJ
40000
40001These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets.
40002
40003@table @r
40004
40005@item 2
4000616-bit Thumb mode breakpoint.
40007
40008@item 3
4000932-bit Thumb mode (Thumb-2) breakpoint.
40010
40011@item 4
02b67415 4001232-bit @acronym{ARM} mode breakpoint.
a1dcb23a
DJ
40013
40014@end table
40015
02b67415
MR
40016@node MIPS-Specific Protocol Details
40017@subsection @acronym{MIPS}-specific Protocol Details
40018
40019@menu
40020* MIPS Register packet Format::
4cc0665f 40021* MIPS Breakpoint Kinds::
02b67415 40022@end menu
a1dcb23a 40023
02b67415
MR
40024@node MIPS Register packet Format
40025@subsubsection @acronym{MIPS} Register Packet Format
eb17f351 40026@cindex register packet format, @acronym{MIPS}
eb12ee30 40027
b8ff78ce 40028The following @code{g}/@code{G} packets have previously been defined.
ee2d5c50
AC
40029In the below, some thirty-two bit registers are transferred as
40030sixty-four bits. Those registers should be zero/sign extended (which?)
599b237a
BW
40031to fill the space allocated. Register bytes are transferred in target
40032byte order. The two nibbles within a register byte are transferred
02b67415 40033most-significant -- least-significant.
eb12ee30 40034
ee2d5c50 40035@table @r
eb12ee30 40036
8e04817f 40037@item MIPS32
599b237a 40038All registers are transferred as thirty-two bit quantities in the order:
8e04817f
AC
4003932 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point
40040registers; fsr; fir; fp.
eb12ee30 40041
8e04817f 40042@item MIPS64
599b237a 40043All registers are transferred as sixty-four bit quantities (including
8e04817f
AC
40044thirty-two bit registers such as @code{sr}). The ordering is the same
40045as @code{MIPS32}.
eb12ee30 40046
ee2d5c50
AC
40047@end table
40048
4cc0665f
MR
40049@node MIPS Breakpoint Kinds
40050@subsubsection @acronym{MIPS} Breakpoint Kinds
40051@cindex breakpoint kinds, @acronym{MIPS}
40052
40053These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets.
40054
40055@table @r
40056
40057@item 2
4005816-bit @acronym{MIPS16} mode breakpoint.
40059
40060@item 3
4006116-bit @acronym{microMIPS} mode breakpoint.
40062
40063@item 4
4006432-bit standard @acronym{MIPS} mode breakpoint.
40065
40066@item 5
4006732-bit @acronym{microMIPS} mode breakpoint.
40068
40069@end table
40070
9d29849a
JB
40071@node Tracepoint Packets
40072@section Tracepoint Packets
40073@cindex tracepoint packets
40074@cindex packets, tracepoint
40075
40076Here we describe the packets @value{GDBN} uses to implement
40077tracepoints (@pxref{Tracepoints}).
40078
40079@table @samp
40080
7a697b8d 40081@item QTDP:@var{n}:@var{addr}:@var{ena}:@var{step}:@var{pass}[:F@var{flen}][:X@var{len},@var{bytes}]@r{[}-@r{]}
c614397c 40082@cindex @samp{QTDP} packet
9d29849a
JB
40083Create a new tracepoint, number @var{n}, at @var{addr}. If @var{ena}
40084is @samp{E}, then the tracepoint is enabled; if it is @samp{D}, then
697aa1b7
EZ
40085the tracepoint is disabled. The @var{step} gives the tracepoint's step
40086count, and @var{pass} gives its pass count. If an @samp{F} is present,
7a697b8d
SS
40087then the tracepoint is to be a fast tracepoint, and the @var{flen} is
40088the number of bytes that the target should copy elsewhere to make room
40089for the tracepoint. If an @samp{X} is present, it introduces a
40090tracepoint condition, which consists of a hexadecimal length, followed
40091by a comma and hex-encoded bytes, in a manner similar to action
40092encodings as described below. If the trailing @samp{-} is present,
40093further @samp{QTDP} packets will follow to specify this tracepoint's
40094actions.
9d29849a
JB
40095
40096Replies:
40097@table @samp
40098@item OK
40099The packet was understood and carried out.
dde08ee1
PA
40100@item qRelocInsn
40101@xref{Tracepoint Packets,,Relocate instruction reply packet}.
d57350ea 40102@item @w{}
9d29849a
JB
40103The packet was not recognized.
40104@end table
40105
40106@item QTDP:-@var{n}:@var{addr}:@r{[}S@r{]}@var{action}@dots{}@r{[}-@r{]}
697aa1b7 40107Define actions to be taken when a tracepoint is hit. The @var{n} and
9d29849a
JB
40108@var{addr} must be the same as in the initial @samp{QTDP} packet for
40109this tracepoint. This packet may only be sent immediately after
40110another @samp{QTDP} packet that ended with a @samp{-}. If the
40111trailing @samp{-} is present, further @samp{QTDP} packets will follow,
40112specifying more actions for this tracepoint.
40113
40114In the series of action packets for a given tracepoint, at most one
40115can have an @samp{S} before its first @var{action}. If such a packet
40116is sent, it and the following packets define ``while-stepping''
40117actions. Any prior packets define ordinary actions --- that is, those
40118taken when the tracepoint is first hit. If no action packet has an
40119@samp{S}, then all the packets in the series specify ordinary
40120tracepoint actions.
40121
40122The @samp{@var{action}@dots{}} portion of the packet is a series of
40123actions, concatenated without separators. Each action has one of the
40124following forms:
40125
40126@table @samp
40127
40128@item R @var{mask}
697aa1b7 40129Collect the registers whose bits are set in @var{mask},
599b237a 40130a hexadecimal number whose @var{i}'th bit is set if register number
9d29849a
JB
40131@var{i} should be collected. (The least significant bit is numbered
40132zero.) Note that @var{mask} may be any number of digits long; it may
40133not fit in a 32-bit word.
40134
40135@item M @var{basereg},@var{offset},@var{len}
40136Collect @var{len} bytes of memory starting at the address in register
40137number @var{basereg}, plus @var{offset}. If @var{basereg} is
40138@samp{-1}, then the range has a fixed address: @var{offset} is the
40139address of the lowest byte to collect. The @var{basereg},
599b237a 40140@var{offset}, and @var{len} parameters are all unsigned hexadecimal
9d29849a
JB
40141values (the @samp{-1} value for @var{basereg} is a special case).
40142
40143@item X @var{len},@var{expr}
40144Evaluate @var{expr}, whose length is @var{len}, and collect memory as
697aa1b7 40145it directs. The agent expression @var{expr} is as described in
9d29849a
JB
40146@ref{Agent Expressions}. Each byte of the expression is encoded as a
40147two-digit hex number in the packet; @var{len} is the number of bytes
40148in the expression (and thus one-half the number of hex digits in the
40149packet).
40150
40151@end table
40152
40153Any number of actions may be packed together in a single @samp{QTDP}
40154packet, as long as the packet does not exceed the maximum packet
c1947b85
JB
40155length (400 bytes, for many stubs). There may be only one @samp{R}
40156action per tracepoint, and it must precede any @samp{M} or @samp{X}
40157actions. Any registers referred to by @samp{M} and @samp{X} actions
40158must be collected by a preceding @samp{R} action. (The
40159``while-stepping'' actions are treated as if they were attached to a
40160separate tracepoint, as far as these restrictions are concerned.)
9d29849a
JB
40161
40162Replies:
40163@table @samp
40164@item OK
40165The packet was understood and carried out.
dde08ee1
PA
40166@item qRelocInsn
40167@xref{Tracepoint Packets,,Relocate instruction reply packet}.
d57350ea 40168@item @w{}
9d29849a
JB
40169The packet was not recognized.
40170@end table
40171
409873ef
SS
40172@item QTDPsrc:@var{n}:@var{addr}:@var{type}:@var{start}:@var{slen}:@var{bytes}
40173@cindex @samp{QTDPsrc} packet
40174Specify a source string of tracepoint @var{n} at address @var{addr}.
40175This is useful to get accurate reproduction of the tracepoints
697aa1b7 40176originally downloaded at the beginning of the trace run. The @var{type}
409873ef
SS
40177is the name of the tracepoint part, such as @samp{cond} for the
40178tracepoint's conditional expression (see below for a list of types), while
40179@var{bytes} is the string, encoded in hexadecimal.
40180
40181@var{start} is the offset of the @var{bytes} within the overall source
40182string, while @var{slen} is the total length of the source string.
40183This is intended for handling source strings that are longer than will
40184fit in a single packet.
40185@c Add detailed example when this info is moved into a dedicated
40186@c tracepoint descriptions section.
40187
40188The available string types are @samp{at} for the location,
40189@samp{cond} for the conditional, and @samp{cmd} for an action command.
40190@value{GDBN} sends a separate packet for each command in the action
40191list, in the same order in which the commands are stored in the list.
40192
40193The target does not need to do anything with source strings except
40194report them back as part of the replies to the @samp{qTfP}/@samp{qTsP}
40195query packets.
40196
40197Although this packet is optional, and @value{GDBN} will only send it
40198if the target replies with @samp{TracepointSource} @xref{General
40199Query Packets}, it makes both disconnected tracing and trace files
40200much easier to use. Otherwise the user must be careful that the
40201tracepoints in effect while looking at trace frames are identical to
40202the ones in effect during the trace run; even a small discrepancy
40203could cause @samp{tdump} not to work, or a particular trace frame not
40204be found.
40205
fa3f8d5a 40206@item QTDV:@var{n}:@var{value}:@var{builtin}:@var{name}
f61e138d
SS
40207@cindex define trace state variable, remote request
40208@cindex @samp{QTDV} packet
40209Create a new trace state variable, number @var{n}, with an initial
40210value of @var{value}, which is a 64-bit signed integer. Both @var{n}
40211and @var{value} are encoded as hexadecimal values. @value{GDBN} has
40212the option of not using this packet for initial values of zero; the
40213target should simply create the trace state variables as they are
fa3f8d5a
DT
40214mentioned in expressions. The value @var{builtin} should be 1 (one)
40215if the trace state variable is builtin and 0 (zero) if it is not builtin.
40216@value{GDBN} only sets @var{builtin} to 1 if a previous @samp{qTfV} or
40217@samp{qTsV} packet had it set. The contents of @var{name} is the
40218hex-encoded name (without the leading @samp{$}) of the trace state
40219variable.
f61e138d 40220
9d29849a 40221@item QTFrame:@var{n}
c614397c 40222@cindex @samp{QTFrame} packet
9d29849a
JB
40223Select the @var{n}'th tracepoint frame from the buffer, and use the
40224register and memory contents recorded there to answer subsequent
40225request packets from @value{GDBN}.
40226
40227A successful reply from the stub indicates that the stub has found the
40228requested frame. The response is a series of parts, concatenated
40229without separators, describing the frame we selected. Each part has
40230one of the following forms:
40231
40232@table @samp
40233@item F @var{f}
40234The selected frame is number @var{n} in the trace frame buffer;
599b237a 40235@var{f} is a hexadecimal number. If @var{f} is @samp{-1}, then there
9d29849a
JB
40236was no frame matching the criteria in the request packet.
40237
40238@item T @var{t}
40239The selected trace frame records a hit of tracepoint number @var{t};
599b237a 40240@var{t} is a hexadecimal number.
9d29849a
JB
40241
40242@end table
40243
40244@item QTFrame:pc:@var{addr}
40245Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
40246currently selected frame whose PC is @var{addr};
599b237a 40247@var{addr} is a hexadecimal number.
9d29849a
JB
40248
40249@item QTFrame:tdp:@var{t}
40250Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
40251currently selected frame that is a hit of tracepoint @var{t}; @var{t}
599b237a 40252is a hexadecimal number.
9d29849a
JB
40253
40254@item QTFrame:range:@var{start}:@var{end}
40255Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
40256currently selected frame whose PC is between @var{start} (inclusive)
081dfbf7 40257and @var{end} (inclusive); @var{start} and @var{end} are hexadecimal
9d29849a
JB
40258numbers.
40259
40260@item QTFrame:outside:@var{start}:@var{end}
40261Like @samp{QTFrame:range:@var{start}:@var{end}}, but select the first
081dfbf7 40262frame @emph{outside} the given range of addresses (exclusive).
9d29849a 40263
405f8e94 40264@item qTMinFTPILen
c614397c 40265@cindex @samp{qTMinFTPILen} packet
405f8e94
SS
40266This packet requests the minimum length of instruction at which a fast
40267tracepoint (@pxref{Set Tracepoints}) may be placed. For instance, on
40268the 32-bit x86 architecture, it is possible to use a 4-byte jump, but
40269it depends on the target system being able to create trampolines in
40270the first 64K of memory, which might or might not be possible for that
40271system. So the reply to this packet will be 4 if it is able to
40272arrange for that.
40273
40274Replies:
40275
40276@table @samp
40277@item 0
40278The minimum instruction length is currently unknown.
40279@item @var{length}
697aa1b7
EZ
40280The minimum instruction length is @var{length}, where @var{length}
40281is a hexadecimal number greater or equal to 1. A reply
40282of 1 means that a fast tracepoint may be placed on any instruction
40283regardless of size.
405f8e94
SS
40284@item E
40285An error has occurred.
d57350ea 40286@item @w{}
405f8e94
SS
40287An empty reply indicates that the request is not supported by the stub.
40288@end table
40289
9d29849a 40290@item QTStart
c614397c 40291@cindex @samp{QTStart} packet
dde08ee1
PA
40292Begin the tracepoint experiment. Begin collecting data from
40293tracepoint hits in the trace frame buffer. This packet supports the
40294@samp{qRelocInsn} reply (@pxref{Tracepoint Packets,,Relocate
40295instruction reply packet}).
9d29849a
JB
40296
40297@item QTStop
c614397c 40298@cindex @samp{QTStop} packet
9d29849a
JB
40299End the tracepoint experiment. Stop collecting trace frames.
40300
d248b706
KY
40301@item QTEnable:@var{n}:@var{addr}
40302@anchor{QTEnable}
c614397c 40303@cindex @samp{QTEnable} packet
d248b706
KY
40304Enable tracepoint @var{n} at address @var{addr} in a started tracepoint
40305experiment. If the tracepoint was previously disabled, then collection
40306of data from it will resume.
40307
40308@item QTDisable:@var{n}:@var{addr}
40309@anchor{QTDisable}
c614397c 40310@cindex @samp{QTDisable} packet
d248b706
KY
40311Disable tracepoint @var{n} at address @var{addr} in a started tracepoint
40312experiment. No more data will be collected from the tracepoint unless
40313@samp{QTEnable:@var{n}:@var{addr}} is subsequently issued.
40314
9d29849a 40315@item QTinit
c614397c 40316@cindex @samp{QTinit} packet
9d29849a
JB
40317Clear the table of tracepoints, and empty the trace frame buffer.
40318
40319@item QTro:@var{start1},@var{end1}:@var{start2},@var{end2}:@dots{}
c614397c 40320@cindex @samp{QTro} packet
9d29849a
JB
40321Establish the given ranges of memory as ``transparent''. The stub
40322will answer requests for these ranges from memory's current contents,
40323if they were not collected as part of the tracepoint hit.
40324
40325@value{GDBN} uses this to mark read-only regions of memory, like those
40326containing program code. Since these areas never change, they should
40327still have the same contents they did when the tracepoint was hit, so
40328there's no reason for the stub to refuse to provide their contents.
40329
d5551862 40330@item QTDisconnected:@var{value}
c614397c 40331@cindex @samp{QTDisconnected} packet
d5551862
SS
40332Set the choice to what to do with the tracing run when @value{GDBN}
40333disconnects from the target. A @var{value} of 1 directs the target to
40334continue the tracing run, while 0 tells the target to stop tracing if
40335@value{GDBN} is no longer in the picture.
40336
9d29849a 40337@item qTStatus
c614397c 40338@cindex @samp{qTStatus} packet
9d29849a
JB
40339Ask the stub if there is a trace experiment running right now.
40340
4daf5ac0
SS
40341The reply has the form:
40342
40343@table @samp
40344
40345@item T@var{running}@r{[};@var{field}@r{]}@dots{}
40346@var{running} is a single digit @code{1} if the trace is presently
40347running, or @code{0} if not. It is followed by semicolon-separated
40348optional fields that an agent may use to report additional status.
40349
40350@end table
40351
40352If the trace is not running, the agent may report any of several
40353explanations as one of the optional fields:
40354
40355@table @samp
40356
40357@item tnotrun:0
40358No trace has been run yet.
40359
f196051f
SS
40360@item tstop[:@var{text}]:0
40361The trace was stopped by a user-originated stop command. The optional
40362@var{text} field is a user-supplied string supplied as part of the
40363stop command (for instance, an explanation of why the trace was
40364stopped manually). It is hex-encoded.
4daf5ac0
SS
40365
40366@item tfull:0
40367The trace stopped because the trace buffer filled up.
40368
40369@item tdisconnected:0
40370The trace stopped because @value{GDBN} disconnected from the target.
40371
40372@item tpasscount:@var{tpnum}
40373The trace stopped because tracepoint @var{tpnum} exceeded its pass count.
40374
6c28cbf2
SS
40375@item terror:@var{text}:@var{tpnum}
40376The trace stopped because tracepoint @var{tpnum} had an error. The
40377string @var{text} is available to describe the nature of the error
697aa1b7
EZ
40378(for instance, a divide by zero in the condition expression); it
40379is hex encoded.
6c28cbf2 40380
4daf5ac0
SS
40381@item tunknown:0
40382The trace stopped for some other reason.
40383
40384@end table
40385
33da3f1c
SS
40386Additional optional fields supply statistical and other information.
40387Although not required, they are extremely useful for users monitoring
40388the progress of a trace run. If a trace has stopped, and these
40389numbers are reported, they must reflect the state of the just-stopped
40390trace.
4daf5ac0 40391
9d29849a 40392@table @samp
4daf5ac0
SS
40393
40394@item tframes:@var{n}
40395The number of trace frames in the buffer.
40396
40397@item tcreated:@var{n}
40398The total number of trace frames created during the run. This may
40399be larger than the trace frame count, if the buffer is circular.
40400
40401@item tsize:@var{n}
40402The total size of the trace buffer, in bytes.
40403
40404@item tfree:@var{n}
40405The number of bytes still unused in the buffer.
40406
33da3f1c
SS
40407@item circular:@var{n}
40408The value of the circular trace buffer flag. @code{1} means that the
40409trace buffer is circular and old trace frames will be discarded if
40410necessary to make room, @code{0} means that the trace buffer is linear
40411and may fill up.
40412
40413@item disconn:@var{n}
40414The value of the disconnected tracing flag. @code{1} means that
40415tracing will continue after @value{GDBN} disconnects, @code{0} means
40416that the trace run will stop.
40417
9d29849a
JB
40418@end table
40419
f196051f
SS
40420@item qTP:@var{tp}:@var{addr}
40421@cindex tracepoint status, remote request
40422@cindex @samp{qTP} packet
40423Ask the stub for the current state of tracepoint number @var{tp} at
40424address @var{addr}.
40425
40426Replies:
40427@table @samp
40428@item V@var{hits}:@var{usage}
40429The tracepoint has been hit @var{hits} times so far during the trace
40430run, and accounts for @var{usage} in the trace buffer. Note that
40431@code{while-stepping} steps are not counted as separate hits, but the
40432steps' space consumption is added into the usage number.
40433
40434@end table
40435
f61e138d
SS
40436@item qTV:@var{var}
40437@cindex trace state variable value, remote request
40438@cindex @samp{qTV} packet
40439Ask the stub for the value of the trace state variable number @var{var}.
40440
40441Replies:
40442@table @samp
40443@item V@var{value}
40444The value of the variable is @var{value}. This will be the current
40445value of the variable if the user is examining a running target, or a
40446saved value if the variable was collected in the trace frame that the
40447user is looking at. Note that multiple requests may result in
40448different reply values, such as when requesting values while the
40449program is running.
40450
40451@item U
40452The value of the variable is unknown. This would occur, for example,
40453if the user is examining a trace frame in which the requested variable
40454was not collected.
9d29849a
JB
40455@end table
40456
d5551862 40457@item qTfP
c614397c 40458@cindex @samp{qTfP} packet
d5551862 40459@itemx qTsP
c614397c 40460@cindex @samp{qTsP} packet
d5551862
SS
40461These packets request data about tracepoints that are being used by
40462the target. @value{GDBN} sends @code{qTfP} to get the first piece
40463of data, and multiple @code{qTsP} to get additional pieces. Replies
40464to these packets generally take the form of the @code{QTDP} packets
40465that define tracepoints. (FIXME add detailed syntax)
40466
00bf0b85 40467@item qTfV
c614397c 40468@cindex @samp{qTfV} packet
00bf0b85 40469@itemx qTsV
c614397c 40470@cindex @samp{qTsV} packet
00bf0b85
SS
40471These packets request data about trace state variables that are on the
40472target. @value{GDBN} sends @code{qTfV} to get the first vari of data,
40473and multiple @code{qTsV} to get additional variables. Replies to
40474these packets follow the syntax of the @code{QTDV} packets that define
40475trace state variables.
40476
0fb4aa4b
PA
40477@item qTfSTM
40478@itemx qTsSTM
16bdd41f
YQ
40479@anchor{qTfSTM}
40480@anchor{qTsSTM}
c614397c
YQ
40481@cindex @samp{qTfSTM} packet
40482@cindex @samp{qTsSTM} packet
0fb4aa4b
PA
40483These packets request data about static tracepoint markers that exist
40484in the target program. @value{GDBN} sends @code{qTfSTM} to get the
40485first piece of data, and multiple @code{qTsSTM} to get additional
40486pieces. Replies to these packets take the following form:
40487
40488Reply:
40489@table @samp
40490@item m @var{address}:@var{id}:@var{extra}
40491A single marker
40492@item m @var{address}:@var{id}:@var{extra},@var{address}:@var{id}:@var{extra}@dots{}
40493a comma-separated list of markers
40494@item l
40495(lower case letter @samp{L}) denotes end of list.
40496@item E @var{nn}
697aa1b7 40497An error occurred. The error number @var{nn} is given as hex digits.
d57350ea 40498@item @w{}
0fb4aa4b
PA
40499An empty reply indicates that the request is not supported by the
40500stub.
40501@end table
40502
697aa1b7 40503The @var{address} is encoded in hex;
0fb4aa4b
PA
40504@var{id} and @var{extra} are strings encoded in hex.
40505
40506In response to each query, the target will reply with a list of one or
40507more markers, separated by commas. @value{GDBN} will respond to each
40508reply with a request for more markers (using the @samp{qs} form of the
40509query), until the target responds with @samp{l} (lower-case ell, for
40510@dfn{last}).
40511
40512@item qTSTMat:@var{address}
16bdd41f 40513@anchor{qTSTMat}
c614397c 40514@cindex @samp{qTSTMat} packet
0fb4aa4b
PA
40515This packets requests data about static tracepoint markers in the
40516target program at @var{address}. Replies to this packet follow the
40517syntax of the @samp{qTfSTM} and @code{qTsSTM} packets that list static
40518tracepoint markers.
40519
00bf0b85 40520@item QTSave:@var{filename}
c614397c 40521@cindex @samp{QTSave} packet
00bf0b85 40522This packet directs the target to save trace data to the file name
697aa1b7 40523@var{filename} in the target's filesystem. The @var{filename} is encoded
00bf0b85
SS
40524as a hex string; the interpretation of the file name (relative vs
40525absolute, wild cards, etc) is up to the target.
40526
40527@item qTBuffer:@var{offset},@var{len}
c614397c 40528@cindex @samp{qTBuffer} packet
00bf0b85
SS
40529Return up to @var{len} bytes of the current contents of trace buffer,
40530starting at @var{offset}. The trace buffer is treated as if it were
40531a contiguous collection of traceframes, as per the trace file format.
40532The reply consists as many hex-encoded bytes as the target can deliver
40533in a packet; it is not an error to return fewer than were asked for.
40534A reply consisting of just @code{l} indicates that no bytes are
40535available.
40536
4daf5ac0
SS
40537@item QTBuffer:circular:@var{value}
40538This packet directs the target to use a circular trace buffer if
40539@var{value} is 1, or a linear buffer if the value is 0.
40540
f6f899bf 40541@item QTBuffer:size:@var{size}
28abe188
EZ
40542@anchor{QTBuffer-size}
40543@cindex @samp{QTBuffer size} packet
f6f899bf
HAQ
40544This packet directs the target to make the trace buffer be of size
40545@var{size} if possible. A value of @code{-1} tells the target to
40546use whatever size it prefers.
40547
f196051f 40548@item QTNotes:@r{[}@var{type}:@var{text}@r{]}@r{[};@var{type}:@var{text}@r{]}@dots{}
c614397c 40549@cindex @samp{QTNotes} packet
f196051f
SS
40550This packet adds optional textual notes to the trace run. Allowable
40551types include @code{user}, @code{notes}, and @code{tstop}, the
40552@var{text} fields are arbitrary strings, hex-encoded.
40553
f61e138d 40554@end table
9d29849a 40555
dde08ee1
PA
40556@subsection Relocate instruction reply packet
40557When installing fast tracepoints in memory, the target may need to
40558relocate the instruction currently at the tracepoint address to a
40559different address in memory. For most instructions, a simple copy is
40560enough, but, for example, call instructions that implicitly push the
40561return address on the stack, and relative branches or other
40562PC-relative instructions require offset adjustment, so that the effect
40563of executing the instruction at a different address is the same as if
40564it had executed in the original location.
40565
40566In response to several of the tracepoint packets, the target may also
40567respond with a number of intermediate @samp{qRelocInsn} request
40568packets before the final result packet, to have @value{GDBN} handle
40569this relocation operation. If a packet supports this mechanism, its
40570documentation will explicitly say so. See for example the above
40571descriptions for the @samp{QTStart} and @samp{QTDP} packets. The
40572format of the request is:
40573
40574@table @samp
40575@item qRelocInsn:@var{from};@var{to}
40576
40577This requests @value{GDBN} to copy instruction at address @var{from}
40578to address @var{to}, possibly adjusted so that executing the
40579instruction at @var{to} has the same effect as executing it at
40580@var{from}. @value{GDBN} writes the adjusted instruction to target
40581memory starting at @var{to}.
40582@end table
40583
40584Replies:
40585@table @samp
40586@item qRelocInsn:@var{adjusted_size}
697aa1b7 40587Informs the stub the relocation is complete. The @var{adjusted_size} is
dde08ee1
PA
40588the length in bytes of resulting relocated instruction sequence.
40589@item E @var{NN}
40590A badly formed request was detected, or an error was encountered while
40591relocating the instruction.
40592@end table
40593
a6b151f1
DJ
40594@node Host I/O Packets
40595@section Host I/O Packets
40596@cindex Host I/O, remote protocol
40597@cindex file transfer, remote protocol
40598
40599The @dfn{Host I/O} packets allow @value{GDBN} to perform I/O
40600operations on the far side of a remote link. For example, Host I/O is
40601used to upload and download files to a remote target with its own
40602filesystem. Host I/O uses the same constant values and data structure
40603layout as the target-initiated File-I/O protocol. However, the
40604Host I/O packets are structured differently. The target-initiated
40605protocol relies on target memory to store parameters and buffers.
40606Host I/O requests are initiated by @value{GDBN}, and the
40607target's memory is not involved. @xref{File-I/O Remote Protocol
40608Extension}, for more details on the target-initiated protocol.
40609
40610The Host I/O request packets all encode a single operation along with
40611its arguments. They have this format:
40612
40613@table @samp
40614
40615@item vFile:@var{operation}: @var{parameter}@dots{}
40616@var{operation} is the name of the particular request; the target
40617should compare the entire packet name up to the second colon when checking
40618for a supported operation. The format of @var{parameter} depends on
40619the operation. Numbers are always passed in hexadecimal. Negative
40620numbers have an explicit minus sign (i.e.@: two's complement is not
40621used). Strings (e.g.@: filenames) are encoded as a series of
40622hexadecimal bytes. The last argument to a system call may be a
40623buffer of escaped binary data (@pxref{Binary Data}).
40624
40625@end table
40626
40627The valid responses to Host I/O packets are:
40628
40629@table @samp
40630
40631@item F @var{result} [, @var{errno}] [; @var{attachment}]
40632@var{result} is the integer value returned by this operation, usually
40633non-negative for success and -1 for errors. If an error has occured,
697aa1b7 40634@var{errno} will be included in the result specifying a
a6b151f1
DJ
40635value defined by the File-I/O protocol (@pxref{Errno Values}). For
40636operations which return data, @var{attachment} supplies the data as a
40637binary buffer. Binary buffers in response packets are escaped in the
40638normal way (@pxref{Binary Data}). See the individual packet
40639documentation for the interpretation of @var{result} and
40640@var{attachment}.
40641
d57350ea 40642@item @w{}
a6b151f1
DJ
40643An empty response indicates that this operation is not recognized.
40644
40645@end table
40646
40647These are the supported Host I/O operations:
40648
40649@table @samp
697aa1b7
EZ
40650@item vFile:open: @var{filename}, @var{flags}, @var{mode}
40651Open a file at @var{filename} and return a file descriptor for it, or
40652return -1 if an error occurs. The @var{filename} is a string,
a6b151f1
DJ
40653@var{flags} is an integer indicating a mask of open flags
40654(@pxref{Open Flags}), and @var{mode} is an integer indicating a mask
40655of mode bits to use if the file is created (@pxref{mode_t Values}).
c1c25a1a 40656@xref{open}, for details of the open flags and mode values.
a6b151f1
DJ
40657
40658@item vFile:close: @var{fd}
40659Close the open file corresponding to @var{fd} and return 0, or
40660-1 if an error occurs.
40661
40662@item vFile:pread: @var{fd}, @var{count}, @var{offset}
40663Read data from the open file corresponding to @var{fd}. Up to
40664@var{count} bytes will be read from the file, starting at @var{offset}
40665relative to the start of the file. The target may read fewer bytes;
40666common reasons include packet size limits and an end-of-file
40667condition. The number of bytes read is returned. Zero should only be
40668returned for a successful read at the end of the file, or if
40669@var{count} was zero.
40670
40671The data read should be returned as a binary attachment on success.
40672If zero bytes were read, the response should include an empty binary
40673attachment (i.e.@: a trailing semicolon). The return value is the
40674number of target bytes read; the binary attachment may be longer if
40675some characters were escaped.
40676
40677@item vFile:pwrite: @var{fd}, @var{offset}, @var{data}
40678Write @var{data} (a binary buffer) to the open file corresponding
40679to @var{fd}. Start the write at @var{offset} from the start of the
40680file. Unlike many @code{write} system calls, there is no
40681separate @var{count} argument; the length of @var{data} in the
40682packet is used. @samp{vFile:write} returns the number of bytes written,
40683which may be shorter than the length of @var{data}, or -1 if an
40684error occurred.
40685
0a93529c
GB
40686@item vFile:fstat: @var{fd}
40687Get information about the open file corresponding to @var{fd}.
40688On success the information is returned as a binary attachment
40689and the return value is the size of this attachment in bytes.
40690If an error occurs the return value is -1. The format of the
40691returned binary attachment is as described in @ref{struct stat}.
40692
697aa1b7
EZ
40693@item vFile:unlink: @var{filename}
40694Delete the file at @var{filename} on the target. Return 0,
40695or -1 if an error occurs. The @var{filename} is a string.
a6b151f1 40696
b9e7b9c3
UW
40697@item vFile:readlink: @var{filename}
40698Read value of symbolic link @var{filename} on the target. Return
40699the number of bytes read, or -1 if an error occurs.
40700
40701The data read should be returned as a binary attachment on success.
40702If zero bytes were read, the response should include an empty binary
40703attachment (i.e.@: a trailing semicolon). The return value is the
40704number of target bytes read; the binary attachment may be longer if
40705some characters were escaped.
40706
15a201c8
GB
40707@item vFile:setfs: @var{pid}
40708Select the filesystem on which @code{vFile} operations with
40709@var{filename} arguments will operate. This is required for
40710@value{GDBN} to be able to access files on remote targets where
40711the remote stub does not share a common filesystem with the
40712inferior(s).
40713
40714If @var{pid} is nonzero, select the filesystem as seen by process
40715@var{pid}. If @var{pid} is zero, select the filesystem as seen by
40716the remote stub. Return 0 on success, or -1 if an error occurs.
40717If @code{vFile:setfs:} indicates success, the selected filesystem
40718remains selected until the next successful @code{vFile:setfs:}
40719operation.
40720
a6b151f1
DJ
40721@end table
40722
9a6253be
KB
40723@node Interrupts
40724@section Interrupts
40725@cindex interrupts (remote protocol)
de979965 40726@anchor{interrupting remote targets}
9a6253be 40727
de979965
PA
40728In all-stop mode, when a program on the remote target is running,
40729@value{GDBN} may attempt to interrupt it by sending a @samp{Ctrl-C},
40730@code{BREAK} or a @code{BREAK} followed by @code{g}, control of which
40731is specified via @value{GDBN}'s @samp{interrupt-sequence}.
9a6253be
KB
40732
40733The precise meaning of @code{BREAK} is defined by the transport
8775bb90
MS
40734mechanism and may, in fact, be undefined. @value{GDBN} does not
40735currently define a @code{BREAK} mechanism for any of the network
40736interfaces except for TCP, in which case @value{GDBN} sends the
40737@code{telnet} BREAK sequence.
9a6253be
KB
40738
40739@samp{Ctrl-C}, on the other hand, is defined and implemented for all
40740transport mechanisms. It is represented by sending the single byte
40741@code{0x03} without any of the usual packet overhead described in
40742the Overview section (@pxref{Overview}). When a @code{0x03} byte is
40743transmitted as part of a packet, it is considered to be packet data
40744and does @emph{not} represent an interrupt. E.g., an @samp{X} packet
0876f84a 40745(@pxref{X packet}), used for binary downloads, may include an unescaped
9a6253be
KB
40746@code{0x03} as part of its packet.
40747
9a7071a8
JB
40748@code{BREAK} followed by @code{g} is also known as Magic SysRq g.
40749When Linux kernel receives this sequence from serial port,
40750it stops execution and connects to gdb.
40751
de979965
PA
40752In non-stop mode, because packet resumptions are asynchronous
40753(@pxref{vCont packet}), @value{GDBN} is always free to send a remote
40754command to the remote stub, even when the target is running. For that
40755reason, @value{GDBN} instead sends a regular packet (@pxref{vCtrlC
40756packet}) with the usual packet framing instead of the single byte
40757@code{0x03}.
40758
9a6253be
KB
40759Stubs are not required to recognize these interrupt mechanisms and the
40760precise meaning associated with receipt of the interrupt is
8b23ecc4
SL
40761implementation defined. If the target supports debugging of multiple
40762threads and/or processes, it should attempt to interrupt all
40763currently-executing threads and processes.
40764If the stub is successful at interrupting the
40765running program, it should send one of the stop
40766reply packets (@pxref{Stop Reply Packets}) to @value{GDBN} as a result
40767of successfully stopping the program in all-stop mode, and a stop reply
40768for each stopped thread in non-stop mode.
40769Interrupts received while the
cde67b27
YQ
40770program is stopped are queued and the program will be interrupted when
40771it is resumed next time.
8b23ecc4
SL
40772
40773@node Notification Packets
40774@section Notification Packets
40775@cindex notification packets
40776@cindex packets, notification
40777
40778The @value{GDBN} remote serial protocol includes @dfn{notifications},
40779packets that require no acknowledgment. Both the GDB and the stub
40780may send notifications (although the only notifications defined at
40781present are sent by the stub). Notifications carry information
40782without incurring the round-trip latency of an acknowledgment, and so
40783are useful for low-impact communications where occasional packet loss
40784is not a problem.
40785
40786A notification packet has the form @samp{% @var{data} #
40787@var{checksum}}, where @var{data} is the content of the notification,
40788and @var{checksum} is a checksum of @var{data}, computed and formatted
40789as for ordinary @value{GDBN} packets. A notification's @var{data}
40790never contains @samp{$}, @samp{%} or @samp{#} characters. Upon
40791receiving a notification, the recipient sends no @samp{+} or @samp{-}
40792to acknowledge the notification's receipt or to report its corruption.
40793
40794Every notification's @var{data} begins with a name, which contains no
40795colon characters, followed by a colon character.
40796
40797Recipients should silently ignore corrupted notifications and
40798notifications they do not understand. Recipients should restart
40799timeout periods on receipt of a well-formed notification, whether or
40800not they understand it.
40801
40802Senders should only send the notifications described here when this
40803protocol description specifies that they are permitted. In the
40804future, we may extend the protocol to permit existing notifications in
40805new contexts; this rule helps older senders avoid confusing newer
40806recipients.
40807
40808(Older versions of @value{GDBN} ignore bytes received until they see
40809the @samp{$} byte that begins an ordinary packet, so new stubs may
40810transmit notifications without fear of confusing older clients. There
40811are no notifications defined for @value{GDBN} to send at the moment, but we
40812assume that most older stubs would ignore them, as well.)
40813
8dbe8ece 40814Each notification is comprised of three parts:
8b23ecc4 40815@table @samp
8dbe8ece
YQ
40816@item @var{name}:@var{event}
40817The notification packet is sent by the side that initiates the
40818exchange (currently, only the stub does that), with @var{event}
697aa1b7
EZ
40819carrying the specific information about the notification, and
40820@var{name} specifying the name of the notification.
8dbe8ece
YQ
40821@item @var{ack}
40822The acknowledge sent by the other side, usually @value{GDBN}, to
40823acknowledge the exchange and request the event.
40824@end table
40825
40826The purpose of an asynchronous notification mechanism is to report to
40827@value{GDBN} that something interesting happened in the remote stub.
40828
40829The remote stub may send notification @var{name}:@var{event}
40830at any time, but @value{GDBN} acknowledges the notification when
40831appropriate. The notification event is pending before @value{GDBN}
40832acknowledges. Only one notification at a time may be pending; if
40833additional events occur before @value{GDBN} has acknowledged the
40834previous notification, they must be queued by the stub for later
40835synchronous transmission in response to @var{ack} packets from
40836@value{GDBN}. Because the notification mechanism is unreliable,
40837the stub is permitted to resend a notification if it believes
40838@value{GDBN} may not have received it.
40839
40840Specifically, notifications may appear when @value{GDBN} is not
40841otherwise reading input from the stub, or when @value{GDBN} is
40842expecting to read a normal synchronous response or a
40843@samp{+}/@samp{-} acknowledgment to a packet it has sent.
40844Notification packets are distinct from any other communication from
40845the stub so there is no ambiguity.
40846
40847After receiving a notification, @value{GDBN} shall acknowledge it by
40848sending a @var{ack} packet as a regular, synchronous request to the
40849stub. Such acknowledgment is not required to happen immediately, as
40850@value{GDBN} is permitted to send other, unrelated packets to the
40851stub first, which the stub should process normally.
40852
40853Upon receiving a @var{ack} packet, if the stub has other queued
40854events to report to @value{GDBN}, it shall respond by sending a
40855normal @var{event}. @value{GDBN} shall then send another @var{ack}
40856packet to solicit further responses; again, it is permitted to send
40857other, unrelated packets as well which the stub should process
40858normally.
40859
40860If the stub receives a @var{ack} packet and there are no additional
40861@var{event} to report, the stub shall return an @samp{OK} response.
40862At this point, @value{GDBN} has finished processing a notification
40863and the stub has completed sending any queued events. @value{GDBN}
40864won't accept any new notifications until the final @samp{OK} is
40865received . If further notification events occur, the stub shall send
40866a new notification, @value{GDBN} shall accept the notification, and
40867the process shall be repeated.
40868
40869The process of asynchronous notification can be illustrated by the
40870following example:
40871@smallexample
4435e1cc 40872<- @code{%Stop:T0505:98e7ffbf;04:4ce6ffbf;08:b1b6e54c;thread:p7526.7526;core:0;}
8dbe8ece
YQ
40873@code{...}
40874-> @code{vStopped}
40875<- @code{T0505:68f37db7;04:40f37db7;08:63850408;thread:p7526.7528;core:0;}
40876-> @code{vStopped}
40877<- @code{T0505:68e3fdb6;04:40e3fdb6;08:63850408;thread:p7526.7529;core:0;}
40878-> @code{vStopped}
40879<- @code{OK}
40880@end smallexample
40881
40882The following notifications are defined:
40883@multitable @columnfractions 0.12 0.12 0.38 0.38
40884
40885@item Notification
40886@tab Ack
40887@tab Event
40888@tab Description
40889
40890@item Stop
40891@tab vStopped
40892@tab @var{reply}. The @var{reply} has the form of a stop reply, as
8b23ecc4
SL
40893described in @ref{Stop Reply Packets}. Refer to @ref{Remote Non-Stop},
40894for information on how these notifications are acknowledged by
40895@value{GDBN}.
8dbe8ece
YQ
40896@tab Report an asynchronous stop event in non-stop mode.
40897
40898@end multitable
8b23ecc4
SL
40899
40900@node Remote Non-Stop
40901@section Remote Protocol Support for Non-Stop Mode
40902
40903@value{GDBN}'s remote protocol supports non-stop debugging of
40904multi-threaded programs, as described in @ref{Non-Stop Mode}. If the stub
40905supports non-stop mode, it should report that to @value{GDBN} by including
40906@samp{QNonStop+} in its @samp{qSupported} response (@pxref{qSupported}).
40907
40908@value{GDBN} typically sends a @samp{QNonStop} packet only when
40909establishing a new connection with the stub. Entering non-stop mode
40910does not alter the state of any currently-running threads, but targets
40911must stop all threads in any already-attached processes when entering
40912all-stop mode. @value{GDBN} uses the @samp{?} packet as necessary to
40913probe the target state after a mode change.
40914
40915In non-stop mode, when an attached process encounters an event that
40916would otherwise be reported with a stop reply, it uses the
40917asynchronous notification mechanism (@pxref{Notification Packets}) to
40918inform @value{GDBN}. In contrast to all-stop mode, where all threads
40919in all processes are stopped when a stop reply is sent, in non-stop
40920mode only the thread reporting the stop event is stopped. That is,
40921when reporting a @samp{S} or @samp{T} response to indicate completion
40922of a step operation, hitting a breakpoint, or a fault, only the
40923affected thread is stopped; any other still-running threads continue
40924to run. When reporting a @samp{W} or @samp{X} response, all running
40925threads belonging to other attached processes continue to run.
40926
8b23ecc4
SL
40927In non-stop mode, the target shall respond to the @samp{?} packet as
40928follows. First, any incomplete stop reply notification/@samp{vStopped}
40929sequence in progress is abandoned. The target must begin a new
40930sequence reporting stop events for all stopped threads, whether or not
40931it has previously reported those events to @value{GDBN}. The first
40932stop reply is sent as a synchronous reply to the @samp{?} packet, and
40933subsequent stop replies are sent as responses to @samp{vStopped} packets
40934using the mechanism described above. The target must not send
40935asynchronous stop reply notifications until the sequence is complete.
40936If all threads are running when the target receives the @samp{?} packet,
40937or if the target is not attached to any process, it shall respond
40938@samp{OK}.
9a6253be 40939
f7e6eed5
PA
40940If the stub supports non-stop mode, it should also support the
40941@samp{swbreak} stop reason if software breakpoints are supported, and
40942the @samp{hwbreak} stop reason if hardware breakpoints are supported
40943(@pxref{swbreak stop reason}). This is because given the asynchronous
40944nature of non-stop mode, between the time a thread hits a breakpoint
40945and the time the event is finally processed by @value{GDBN}, the
40946breakpoint may have already been removed from the target. Due to
40947this, @value{GDBN} needs to be able to tell whether a trap stop was
40948caused by a delayed breakpoint event, which should be ignored, as
40949opposed to a random trap signal, which should be reported to the user.
40950Note the @samp{swbreak} feature implies that the target is responsible
40951for adjusting the PC when a software breakpoint triggers, if
40952necessary, such as on the x86 architecture.
40953
a6f3e723
SL
40954@node Packet Acknowledgment
40955@section Packet Acknowledgment
40956
40957@cindex acknowledgment, for @value{GDBN} remote
40958@cindex packet acknowledgment, for @value{GDBN} remote
40959By default, when either the host or the target machine receives a packet,
40960the first response expected is an acknowledgment: either @samp{+} (to indicate
40961the package was received correctly) or @samp{-} (to request retransmission).
40962This mechanism allows the @value{GDBN} remote protocol to operate over
40963unreliable transport mechanisms, such as a serial line.
40964
40965In cases where the transport mechanism is itself reliable (such as a pipe or
40966TCP connection), the @samp{+}/@samp{-} acknowledgments are redundant.
40967It may be desirable to disable them in that case to reduce communication
40968overhead, or for other reasons. This can be accomplished by means of the
40969@samp{QStartNoAckMode} packet; @pxref{QStartNoAckMode}.
40970
40971When in no-acknowledgment mode, neither the stub nor @value{GDBN} shall send or
40972expect @samp{+}/@samp{-} protocol acknowledgments. The packet
40973and response format still includes the normal checksum, as described in
40974@ref{Overview}, but the checksum may be ignored by the receiver.
40975
40976If the stub supports @samp{QStartNoAckMode} and prefers to operate in
40977no-acknowledgment mode, it should report that to @value{GDBN}
40978by including @samp{QStartNoAckMode+} in its response to @samp{qSupported};
40979@pxref{qSupported}.
40980If @value{GDBN} also supports @samp{QStartNoAckMode} and it has not been
40981disabled via the @code{set remote noack-packet off} command
40982(@pxref{Remote Configuration}),
40983@value{GDBN} may then send a @samp{QStartNoAckMode} packet to the stub.
40984Only then may the stub actually turn off packet acknowledgments.
40985@value{GDBN} sends a final @samp{+} acknowledgment of the stub's @samp{OK}
40986response, which can be safely ignored by the stub.
40987
40988Note that @code{set remote noack-packet} command only affects negotiation
40989between @value{GDBN} and the stub when subsequent connections are made;
40990it does not affect the protocol acknowledgment state for any current
40991connection.
40992Since @samp{+}/@samp{-} acknowledgments are enabled by default when a
40993new connection is established,
40994there is also no protocol request to re-enable the acknowledgments
40995for the current connection, once disabled.
40996
ee2d5c50
AC
40997@node Examples
40998@section Examples
eb12ee30 40999
8e04817f
AC
41000Example sequence of a target being re-started. Notice how the restart
41001does not get any direct output:
eb12ee30 41002
474c8240 41003@smallexample
d2c6833e
AC
41004-> @code{R00}
41005<- @code{+}
8e04817f 41006@emph{target restarts}
d2c6833e 41007-> @code{?}
8e04817f 41008<- @code{+}
d2c6833e
AC
41009<- @code{T001:1234123412341234}
41010-> @code{+}
474c8240 41011@end smallexample
eb12ee30 41012
8e04817f 41013Example sequence of a target being stepped by a single instruction:
eb12ee30 41014
474c8240 41015@smallexample
d2c6833e 41016-> @code{G1445@dots{}}
8e04817f 41017<- @code{+}
d2c6833e
AC
41018-> @code{s}
41019<- @code{+}
41020@emph{time passes}
41021<- @code{T001:1234123412341234}
8e04817f 41022-> @code{+}
d2c6833e 41023-> @code{g}
8e04817f 41024<- @code{+}
d2c6833e
AC
41025<- @code{1455@dots{}}
41026-> @code{+}
474c8240 41027@end smallexample
eb12ee30 41028
79a6e687
BW
41029@node File-I/O Remote Protocol Extension
41030@section File-I/O Remote Protocol Extension
0ce1b118
CV
41031@cindex File-I/O remote protocol extension
41032
41033@menu
41034* File-I/O Overview::
79a6e687
BW
41035* Protocol Basics::
41036* The F Request Packet::
41037* The F Reply Packet::
41038* The Ctrl-C Message::
0ce1b118 41039* Console I/O::
79a6e687 41040* List of Supported Calls::
db2e3e2e 41041* Protocol-specific Representation of Datatypes::
0ce1b118
CV
41042* Constants::
41043* File-I/O Examples::
41044@end menu
41045
41046@node File-I/O Overview
41047@subsection File-I/O Overview
41048@cindex file-i/o overview
41049
9c16f35a 41050The @dfn{File I/O remote protocol extension} (short: File-I/O) allows the
fc320d37 41051target to use the host's file system and console I/O to perform various
0ce1b118 41052system calls. System calls on the target system are translated into a
fc320d37
SL
41053remote protocol packet to the host system, which then performs the needed
41054actions and returns a response packet to the target system.
0ce1b118
CV
41055This simulates file system operations even on targets that lack file systems.
41056
fc320d37
SL
41057The protocol is defined to be independent of both the host and target systems.
41058It uses its own internal representation of datatypes and values. Both
0ce1b118 41059@value{GDBN} and the target's @value{GDBN} stub are responsible for
fc320d37
SL
41060translating the system-dependent value representations into the internal
41061protocol representations when data is transmitted.
0ce1b118 41062
fc320d37
SL
41063The communication is synchronous. A system call is possible only when
41064@value{GDBN} is waiting for a response from the @samp{C}, @samp{c}, @samp{S}
41065or @samp{s} packets. While @value{GDBN} handles the request for a system call,
0ce1b118 41066the target is stopped to allow deterministic access to the target's
fc320d37
SL
41067memory. Therefore File-I/O is not interruptible by target signals. On
41068the other hand, it is possible to interrupt File-I/O by a user interrupt
c8aa23ab 41069(@samp{Ctrl-C}) within @value{GDBN}.
0ce1b118
CV
41070
41071The target's request to perform a host system call does not finish
41072the latest @samp{C}, @samp{c}, @samp{S} or @samp{s} action. That means,
41073after finishing the system call, the target returns to continuing the
41074previous activity (continue, step). No additional continue or step
41075request from @value{GDBN} is required.
41076
41077@smallexample
f7dc1244 41078(@value{GDBP}) continue
0ce1b118
CV
41079 <- target requests 'system call X'
41080 target is stopped, @value{GDBN} executes system call
3f94c067
BW
41081 -> @value{GDBN} returns result
41082 ... target continues, @value{GDBN} returns to wait for the target
0ce1b118
CV
41083 <- target hits breakpoint and sends a Txx packet
41084@end smallexample
41085
fc320d37
SL
41086The protocol only supports I/O on the console and to regular files on
41087the host file system. Character or block special devices, pipes,
41088named pipes, sockets or any other communication method on the host
0ce1b118
CV
41089system are not supported by this protocol.
41090
8b23ecc4
SL
41091File I/O is not supported in non-stop mode.
41092
79a6e687
BW
41093@node Protocol Basics
41094@subsection Protocol Basics
0ce1b118
CV
41095@cindex protocol basics, file-i/o
41096
fc320d37
SL
41097The File-I/O protocol uses the @code{F} packet as the request as well
41098as reply packet. Since a File-I/O system call can only occur when
41099@value{GDBN} is waiting for a response from the continuing or stepping target,
41100the File-I/O request is a reply that @value{GDBN} has to expect as a result
41101of a previous @samp{C}, @samp{c}, @samp{S} or @samp{s} packet.
0ce1b118
CV
41102This @code{F} packet contains all information needed to allow @value{GDBN}
41103to call the appropriate host system call:
41104
41105@itemize @bullet
b383017d 41106@item
0ce1b118
CV
41107A unique identifier for the requested system call.
41108
41109@item
41110All parameters to the system call. Pointers are given as addresses
41111in the target memory address space. Pointers to strings are given as
b383017d 41112pointer/length pair. Numerical values are given as they are.
db2e3e2e 41113Numerical control flags are given in a protocol-specific representation.
0ce1b118
CV
41114
41115@end itemize
41116
fc320d37 41117At this point, @value{GDBN} has to perform the following actions.
0ce1b118
CV
41118
41119@itemize @bullet
b383017d 41120@item
fc320d37
SL
41121If the parameters include pointer values to data needed as input to a
41122system call, @value{GDBN} requests this data from the target with a
0ce1b118
CV
41123standard @code{m} packet request. This additional communication has to be
41124expected by the target implementation and is handled as any other @code{m}
41125packet.
41126
41127@item
41128@value{GDBN} translates all value from protocol representation to host
41129representation as needed. Datatypes are coerced into the host types.
41130
41131@item
fc320d37 41132@value{GDBN} calls the system call.
0ce1b118
CV
41133
41134@item
41135It then coerces datatypes back to protocol representation.
41136
41137@item
fc320d37
SL
41138If the system call is expected to return data in buffer space specified
41139by pointer parameters to the call, the data is transmitted to the
0ce1b118
CV
41140target using a @code{M} or @code{X} packet. This packet has to be expected
41141by the target implementation and is handled as any other @code{M} or @code{X}
41142packet.
41143
41144@end itemize
41145
41146Eventually @value{GDBN} replies with another @code{F} packet which contains all
41147necessary information for the target to continue. This at least contains
41148
41149@itemize @bullet
41150@item
41151Return value.
41152
41153@item
41154@code{errno}, if has been changed by the system call.
41155
41156@item
41157``Ctrl-C'' flag.
41158
41159@end itemize
41160
41161After having done the needed type and value coercion, the target continues
41162the latest continue or step action.
41163
79a6e687
BW
41164@node The F Request Packet
41165@subsection The @code{F} Request Packet
0ce1b118
CV
41166@cindex file-i/o request packet
41167@cindex @code{F} request packet
41168
41169The @code{F} request packet has the following format:
41170
41171@table @samp
fc320d37 41172@item F@var{call-id},@var{parameter@dots{}}
0ce1b118
CV
41173
41174@var{call-id} is the identifier to indicate the host system call to be called.
41175This is just the name of the function.
41176
fc320d37
SL
41177@var{parameter@dots{}} are the parameters to the system call.
41178Parameters are hexadecimal integer values, either the actual values in case
41179of scalar datatypes, pointers to target buffer space in case of compound
41180datatypes and unspecified memory areas, or pointer/length pairs in case
41181of string parameters. These are appended to the @var{call-id} as a
41182comma-delimited list. All values are transmitted in ASCII
41183string representation, pointer/length pairs separated by a slash.
0ce1b118 41184
b383017d 41185@end table
0ce1b118 41186
fc320d37 41187
0ce1b118 41188
79a6e687
BW
41189@node The F Reply Packet
41190@subsection The @code{F} Reply Packet
0ce1b118
CV
41191@cindex file-i/o reply packet
41192@cindex @code{F} reply packet
41193
41194The @code{F} reply packet has the following format:
41195
41196@table @samp
41197
d3bdde98 41198@item F@var{retcode},@var{errno},@var{Ctrl-C flag};@var{call-specific attachment}
0ce1b118
CV
41199
41200@var{retcode} is the return code of the system call as hexadecimal value.
41201
db2e3e2e
BW
41202@var{errno} is the @code{errno} set by the call, in protocol-specific
41203representation.
0ce1b118
CV
41204This parameter can be omitted if the call was successful.
41205
fc320d37
SL
41206@var{Ctrl-C flag} is only sent if the user requested a break. In this
41207case, @var{errno} must be sent as well, even if the call was successful.
41208The @var{Ctrl-C flag} itself consists of the character @samp{C}:
0ce1b118
CV
41209
41210@smallexample
41211F0,0,C
41212@end smallexample
41213
41214@noindent
fc320d37 41215or, if the call was interrupted before the host call has been performed:
0ce1b118
CV
41216
41217@smallexample
41218F-1,4,C
41219@end smallexample
41220
41221@noindent
db2e3e2e 41222assuming 4 is the protocol-specific representation of @code{EINTR}.
0ce1b118
CV
41223
41224@end table
41225
0ce1b118 41226
79a6e687
BW
41227@node The Ctrl-C Message
41228@subsection The @samp{Ctrl-C} Message
0ce1b118
CV
41229@cindex ctrl-c message, in file-i/o protocol
41230
c8aa23ab 41231If the @samp{Ctrl-C} flag is set in the @value{GDBN}
79a6e687 41232reply packet (@pxref{The F Reply Packet}),
fc320d37 41233the target should behave as if it had
0ce1b118 41234gotten a break message. The meaning for the target is ``system call
fc320d37 41235interrupted by @code{SIGINT}''. Consequentially, the target should actually stop
0ce1b118 41236(as with a break message) and return to @value{GDBN} with a @code{T02}
c8aa23ab 41237packet.
fc320d37
SL
41238
41239It's important for the target to know in which
41240state the system call was interrupted. There are two possible cases:
0ce1b118
CV
41241
41242@itemize @bullet
41243@item
41244The system call hasn't been performed on the host yet.
41245
41246@item
41247The system call on the host has been finished.
41248
41249@end itemize
41250
41251These two states can be distinguished by the target by the value of the
41252returned @code{errno}. If it's the protocol representation of @code{EINTR}, the system
41253call hasn't been performed. This is equivalent to the @code{EINTR} handling
41254on POSIX systems. In any other case, the target may presume that the
fc320d37 41255system call has been finished --- successfully or not --- and should behave
0ce1b118
CV
41256as if the break message arrived right after the system call.
41257
fc320d37 41258@value{GDBN} must behave reliably. If the system call has not been called
0ce1b118
CV
41259yet, @value{GDBN} may send the @code{F} reply immediately, setting @code{EINTR} as
41260@code{errno} in the packet. If the system call on the host has been finished
fc320d37
SL
41261before the user requests a break, the full action must be finished by
41262@value{GDBN}. This requires sending @code{M} or @code{X} packets as necessary.
41263The @code{F} packet may only be sent when either nothing has happened
0ce1b118
CV
41264or the full action has been completed.
41265
41266@node Console I/O
41267@subsection Console I/O
41268@cindex console i/o as part of file-i/o
41269
d3e8051b 41270By default and if not explicitly closed by the target system, the file
0ce1b118
CV
41271descriptors 0, 1 and 2 are connected to the @value{GDBN} console. Output
41272on the @value{GDBN} console is handled as any other file output operation
41273(@code{write(1, @dots{})} or @code{write(2, @dots{})}). Console input is handled
41274by @value{GDBN} so that after the target read request from file descriptor
412750 all following typing is buffered until either one of the following
41276conditions is met:
41277
41278@itemize @bullet
41279@item
c8aa23ab 41280The user types @kbd{Ctrl-c}. The behaviour is as explained above, and the
0ce1b118
CV
41281@code{read}
41282system call is treated as finished.
41283
41284@item
7f9087cb 41285The user presses @key{RET}. This is treated as end of input with a trailing
fc320d37 41286newline.
0ce1b118
CV
41287
41288@item
c8aa23ab
EZ
41289The user types @kbd{Ctrl-d}. This is treated as end of input. No trailing
41290character (neither newline nor @samp{Ctrl-D}) is appended to the input.
0ce1b118
CV
41291
41292@end itemize
41293
fc320d37
SL
41294If the user has typed more characters than fit in the buffer given to
41295the @code{read} call, the trailing characters are buffered in @value{GDBN} until
41296either another @code{read(0, @dots{})} is requested by the target, or debugging
41297is stopped at the user's request.
0ce1b118 41298
0ce1b118 41299
79a6e687
BW
41300@node List of Supported Calls
41301@subsection List of Supported Calls
0ce1b118
CV
41302@cindex list of supported file-i/o calls
41303
41304@menu
41305* open::
41306* close::
41307* read::
41308* write::
41309* lseek::
41310* rename::
41311* unlink::
41312* stat/fstat::
41313* gettimeofday::
41314* isatty::
41315* system::
41316@end menu
41317
41318@node open
41319@unnumberedsubsubsec open
41320@cindex open, file-i/o system call
41321
fc320d37
SL
41322@table @asis
41323@item Synopsis:
0ce1b118 41324@smallexample
0ce1b118
CV
41325int open(const char *pathname, int flags);
41326int open(const char *pathname, int flags, mode_t mode);
0ce1b118
CV
41327@end smallexample
41328
fc320d37
SL
41329@item Request:
41330@samp{Fopen,@var{pathptr}/@var{len},@var{flags},@var{mode}}
41331
0ce1b118 41332@noindent
fc320d37 41333@var{flags} is the bitwise @code{OR} of the following values:
0ce1b118
CV
41334
41335@table @code
b383017d 41336@item O_CREAT
0ce1b118
CV
41337If the file does not exist it will be created. The host
41338rules apply as far as file ownership and time stamps
41339are concerned.
41340
b383017d 41341@item O_EXCL
fc320d37 41342When used with @code{O_CREAT}, if the file already exists it is
0ce1b118
CV
41343an error and open() fails.
41344
b383017d 41345@item O_TRUNC
0ce1b118 41346If the file already exists and the open mode allows
fc320d37
SL
41347writing (@code{O_RDWR} or @code{O_WRONLY} is given) it will be
41348truncated to zero length.
0ce1b118 41349
b383017d 41350@item O_APPEND
0ce1b118
CV
41351The file is opened in append mode.
41352
b383017d 41353@item O_RDONLY
0ce1b118
CV
41354The file is opened for reading only.
41355
b383017d 41356@item O_WRONLY
0ce1b118
CV
41357The file is opened for writing only.
41358
b383017d 41359@item O_RDWR
0ce1b118 41360The file is opened for reading and writing.
fc320d37 41361@end table
0ce1b118
CV
41362
41363@noindent
fc320d37 41364Other bits are silently ignored.
0ce1b118 41365
0ce1b118
CV
41366
41367@noindent
fc320d37 41368@var{mode} is the bitwise @code{OR} of the following values:
0ce1b118
CV
41369
41370@table @code
b383017d 41371@item S_IRUSR
0ce1b118
CV
41372User has read permission.
41373
b383017d 41374@item S_IWUSR
0ce1b118
CV
41375User has write permission.
41376
b383017d 41377@item S_IRGRP
0ce1b118
CV
41378Group has read permission.
41379
b383017d 41380@item S_IWGRP
0ce1b118
CV
41381Group has write permission.
41382
b383017d 41383@item S_IROTH
0ce1b118
CV
41384Others have read permission.
41385
b383017d 41386@item S_IWOTH
0ce1b118 41387Others have write permission.
fc320d37 41388@end table
0ce1b118
CV
41389
41390@noindent
fc320d37 41391Other bits are silently ignored.
0ce1b118 41392
0ce1b118 41393
fc320d37
SL
41394@item Return value:
41395@code{open} returns the new file descriptor or -1 if an error
41396occurred.
0ce1b118 41397
fc320d37 41398@item Errors:
0ce1b118
CV
41399
41400@table @code
b383017d 41401@item EEXIST
fc320d37 41402@var{pathname} already exists and @code{O_CREAT} and @code{O_EXCL} were used.
0ce1b118 41403
b383017d 41404@item EISDIR
fc320d37 41405@var{pathname} refers to a directory.
0ce1b118 41406
b383017d 41407@item EACCES
0ce1b118
CV
41408The requested access is not allowed.
41409
41410@item ENAMETOOLONG
fc320d37 41411@var{pathname} was too long.
0ce1b118 41412
b383017d 41413@item ENOENT
fc320d37 41414A directory component in @var{pathname} does not exist.
0ce1b118 41415
b383017d 41416@item ENODEV
fc320d37 41417@var{pathname} refers to a device, pipe, named pipe or socket.
0ce1b118 41418
b383017d 41419@item EROFS
fc320d37 41420@var{pathname} refers to a file on a read-only filesystem and
0ce1b118
CV
41421write access was requested.
41422
b383017d 41423@item EFAULT
fc320d37 41424@var{pathname} is an invalid pointer value.
0ce1b118 41425
b383017d 41426@item ENOSPC
0ce1b118
CV
41427No space on device to create the file.
41428
b383017d 41429@item EMFILE
0ce1b118
CV
41430The process already has the maximum number of files open.
41431
b383017d 41432@item ENFILE
0ce1b118
CV
41433The limit on the total number of files open on the system
41434has been reached.
41435
b383017d 41436@item EINTR
0ce1b118
CV
41437The call was interrupted by the user.
41438@end table
41439
fc320d37
SL
41440@end table
41441
0ce1b118
CV
41442@node close
41443@unnumberedsubsubsec close
41444@cindex close, file-i/o system call
41445
fc320d37
SL
41446@table @asis
41447@item Synopsis:
0ce1b118 41448@smallexample
0ce1b118 41449int close(int fd);
fc320d37 41450@end smallexample
0ce1b118 41451
fc320d37
SL
41452@item Request:
41453@samp{Fclose,@var{fd}}
0ce1b118 41454
fc320d37
SL
41455@item Return value:
41456@code{close} returns zero on success, or -1 if an error occurred.
0ce1b118 41457
fc320d37 41458@item Errors:
0ce1b118
CV
41459
41460@table @code
b383017d 41461@item EBADF
fc320d37 41462@var{fd} isn't a valid open file descriptor.
0ce1b118 41463
b383017d 41464@item EINTR
0ce1b118
CV
41465The call was interrupted by the user.
41466@end table
41467
fc320d37
SL
41468@end table
41469
0ce1b118
CV
41470@node read
41471@unnumberedsubsubsec read
41472@cindex read, file-i/o system call
41473
fc320d37
SL
41474@table @asis
41475@item Synopsis:
0ce1b118 41476@smallexample
0ce1b118 41477int read(int fd, void *buf, unsigned int count);
fc320d37 41478@end smallexample
0ce1b118 41479
fc320d37
SL
41480@item Request:
41481@samp{Fread,@var{fd},@var{bufptr},@var{count}}
0ce1b118 41482
fc320d37 41483@item Return value:
0ce1b118
CV
41484On success, the number of bytes read is returned.
41485Zero indicates end of file. If count is zero, read
b383017d 41486returns zero as well. On error, -1 is returned.
0ce1b118 41487
fc320d37 41488@item Errors:
0ce1b118
CV
41489
41490@table @code
b383017d 41491@item EBADF
fc320d37 41492@var{fd} is not a valid file descriptor or is not open for
0ce1b118
CV
41493reading.
41494
b383017d 41495@item EFAULT
fc320d37 41496@var{bufptr} is an invalid pointer value.
0ce1b118 41497
b383017d 41498@item EINTR
0ce1b118
CV
41499The call was interrupted by the user.
41500@end table
41501
fc320d37
SL
41502@end table
41503
0ce1b118
CV
41504@node write
41505@unnumberedsubsubsec write
41506@cindex write, file-i/o system call
41507
fc320d37
SL
41508@table @asis
41509@item Synopsis:
0ce1b118 41510@smallexample
0ce1b118 41511int write(int fd, const void *buf, unsigned int count);
fc320d37 41512@end smallexample
0ce1b118 41513
fc320d37
SL
41514@item Request:
41515@samp{Fwrite,@var{fd},@var{bufptr},@var{count}}
0ce1b118 41516
fc320d37 41517@item Return value:
0ce1b118
CV
41518On success, the number of bytes written are returned.
41519Zero indicates nothing was written. On error, -1
41520is returned.
41521
fc320d37 41522@item Errors:
0ce1b118
CV
41523
41524@table @code
b383017d 41525@item EBADF
fc320d37 41526@var{fd} is not a valid file descriptor or is not open for
0ce1b118
CV
41527writing.
41528
b383017d 41529@item EFAULT
fc320d37 41530@var{bufptr} is an invalid pointer value.
0ce1b118 41531
b383017d 41532@item EFBIG
0ce1b118 41533An attempt was made to write a file that exceeds the
db2e3e2e 41534host-specific maximum file size allowed.
0ce1b118 41535
b383017d 41536@item ENOSPC
0ce1b118
CV
41537No space on device to write the data.
41538
b383017d 41539@item EINTR
0ce1b118
CV
41540The call was interrupted by the user.
41541@end table
41542
fc320d37
SL
41543@end table
41544
0ce1b118
CV
41545@node lseek
41546@unnumberedsubsubsec lseek
41547@cindex lseek, file-i/o system call
41548
fc320d37
SL
41549@table @asis
41550@item Synopsis:
0ce1b118 41551@smallexample
0ce1b118 41552long lseek (int fd, long offset, int flag);
0ce1b118
CV
41553@end smallexample
41554
fc320d37
SL
41555@item Request:
41556@samp{Flseek,@var{fd},@var{offset},@var{flag}}
41557
41558@var{flag} is one of:
0ce1b118
CV
41559
41560@table @code
b383017d 41561@item SEEK_SET
fc320d37 41562The offset is set to @var{offset} bytes.
0ce1b118 41563
b383017d 41564@item SEEK_CUR
fc320d37 41565The offset is set to its current location plus @var{offset}
0ce1b118
CV
41566bytes.
41567
b383017d 41568@item SEEK_END
fc320d37 41569The offset is set to the size of the file plus @var{offset}
0ce1b118
CV
41570bytes.
41571@end table
41572
fc320d37 41573@item Return value:
0ce1b118
CV
41574On success, the resulting unsigned offset in bytes from
41575the beginning of the file is returned. Otherwise, a
41576value of -1 is returned.
41577
fc320d37 41578@item Errors:
0ce1b118
CV
41579
41580@table @code
b383017d 41581@item EBADF
fc320d37 41582@var{fd} is not a valid open file descriptor.
0ce1b118 41583
b383017d 41584@item ESPIPE
fc320d37 41585@var{fd} is associated with the @value{GDBN} console.
0ce1b118 41586
b383017d 41587@item EINVAL
fc320d37 41588@var{flag} is not a proper value.
0ce1b118 41589
b383017d 41590@item EINTR
0ce1b118
CV
41591The call was interrupted by the user.
41592@end table
41593
fc320d37
SL
41594@end table
41595
0ce1b118
CV
41596@node rename
41597@unnumberedsubsubsec rename
41598@cindex rename, file-i/o system call
41599
fc320d37
SL
41600@table @asis
41601@item Synopsis:
0ce1b118 41602@smallexample
0ce1b118 41603int rename(const char *oldpath, const char *newpath);
fc320d37 41604@end smallexample
0ce1b118 41605
fc320d37
SL
41606@item Request:
41607@samp{Frename,@var{oldpathptr}/@var{len},@var{newpathptr}/@var{len}}
0ce1b118 41608
fc320d37 41609@item Return value:
0ce1b118
CV
41610On success, zero is returned. On error, -1 is returned.
41611
fc320d37 41612@item Errors:
0ce1b118
CV
41613
41614@table @code
b383017d 41615@item EISDIR
fc320d37 41616@var{newpath} is an existing directory, but @var{oldpath} is not a
0ce1b118
CV
41617directory.
41618
b383017d 41619@item EEXIST
fc320d37 41620@var{newpath} is a non-empty directory.
0ce1b118 41621
b383017d 41622@item EBUSY
fc320d37 41623@var{oldpath} or @var{newpath} is a directory that is in use by some
0ce1b118
CV
41624process.
41625
b383017d 41626@item EINVAL
0ce1b118
CV
41627An attempt was made to make a directory a subdirectory
41628of itself.
41629
b383017d 41630@item ENOTDIR
fc320d37
SL
41631A component used as a directory in @var{oldpath} or new
41632path is not a directory. Or @var{oldpath} is a directory
41633and @var{newpath} exists but is not a directory.
0ce1b118 41634
b383017d 41635@item EFAULT
fc320d37 41636@var{oldpathptr} or @var{newpathptr} are invalid pointer values.
0ce1b118 41637
b383017d 41638@item EACCES
0ce1b118
CV
41639No access to the file or the path of the file.
41640
41641@item ENAMETOOLONG
b383017d 41642
fc320d37 41643@var{oldpath} or @var{newpath} was too long.
0ce1b118 41644
b383017d 41645@item ENOENT
fc320d37 41646A directory component in @var{oldpath} or @var{newpath} does not exist.
0ce1b118 41647
b383017d 41648@item EROFS
0ce1b118
CV
41649The file is on a read-only filesystem.
41650
b383017d 41651@item ENOSPC
0ce1b118
CV
41652The device containing the file has no room for the new
41653directory entry.
41654
b383017d 41655@item EINTR
0ce1b118
CV
41656The call was interrupted by the user.
41657@end table
41658
fc320d37
SL
41659@end table
41660
0ce1b118
CV
41661@node unlink
41662@unnumberedsubsubsec unlink
41663@cindex unlink, file-i/o system call
41664
fc320d37
SL
41665@table @asis
41666@item Synopsis:
0ce1b118 41667@smallexample
0ce1b118 41668int unlink(const char *pathname);
fc320d37 41669@end smallexample
0ce1b118 41670
fc320d37
SL
41671@item Request:
41672@samp{Funlink,@var{pathnameptr}/@var{len}}
0ce1b118 41673
fc320d37 41674@item Return value:
0ce1b118
CV
41675On success, zero is returned. On error, -1 is returned.
41676
fc320d37 41677@item Errors:
0ce1b118
CV
41678
41679@table @code
b383017d 41680@item EACCES
0ce1b118
CV
41681No access to the file or the path of the file.
41682
b383017d 41683@item EPERM
0ce1b118
CV
41684The system does not allow unlinking of directories.
41685
b383017d 41686@item EBUSY
fc320d37 41687The file @var{pathname} cannot be unlinked because it's
0ce1b118
CV
41688being used by another process.
41689
b383017d 41690@item EFAULT
fc320d37 41691@var{pathnameptr} is an invalid pointer value.
0ce1b118
CV
41692
41693@item ENAMETOOLONG
fc320d37 41694@var{pathname} was too long.
0ce1b118 41695
b383017d 41696@item ENOENT
fc320d37 41697A directory component in @var{pathname} does not exist.
0ce1b118 41698
b383017d 41699@item ENOTDIR
0ce1b118
CV
41700A component of the path is not a directory.
41701
b383017d 41702@item EROFS
0ce1b118
CV
41703The file is on a read-only filesystem.
41704
b383017d 41705@item EINTR
0ce1b118
CV
41706The call was interrupted by the user.
41707@end table
41708
fc320d37
SL
41709@end table
41710
0ce1b118
CV
41711@node stat/fstat
41712@unnumberedsubsubsec stat/fstat
41713@cindex fstat, file-i/o system call
41714@cindex stat, file-i/o system call
41715
fc320d37
SL
41716@table @asis
41717@item Synopsis:
0ce1b118 41718@smallexample
0ce1b118
CV
41719int stat(const char *pathname, struct stat *buf);
41720int fstat(int fd, struct stat *buf);
fc320d37 41721@end smallexample
0ce1b118 41722
fc320d37
SL
41723@item Request:
41724@samp{Fstat,@var{pathnameptr}/@var{len},@var{bufptr}}@*
41725@samp{Ffstat,@var{fd},@var{bufptr}}
0ce1b118 41726
fc320d37 41727@item Return value:
0ce1b118
CV
41728On success, zero is returned. On error, -1 is returned.
41729
fc320d37 41730@item Errors:
0ce1b118
CV
41731
41732@table @code
b383017d 41733@item EBADF
fc320d37 41734@var{fd} is not a valid open file.
0ce1b118 41735
b383017d 41736@item ENOENT
fc320d37 41737A directory component in @var{pathname} does not exist or the
0ce1b118
CV
41738path is an empty string.
41739
b383017d 41740@item ENOTDIR
0ce1b118
CV
41741A component of the path is not a directory.
41742
b383017d 41743@item EFAULT
fc320d37 41744@var{pathnameptr} is an invalid pointer value.
0ce1b118 41745
b383017d 41746@item EACCES
0ce1b118
CV
41747No access to the file or the path of the file.
41748
41749@item ENAMETOOLONG
fc320d37 41750@var{pathname} was too long.
0ce1b118 41751
b383017d 41752@item EINTR
0ce1b118
CV
41753The call was interrupted by the user.
41754@end table
41755
fc320d37
SL
41756@end table
41757
0ce1b118
CV
41758@node gettimeofday
41759@unnumberedsubsubsec gettimeofday
41760@cindex gettimeofday, file-i/o system call
41761
fc320d37
SL
41762@table @asis
41763@item Synopsis:
0ce1b118 41764@smallexample
0ce1b118 41765int gettimeofday(struct timeval *tv, void *tz);
fc320d37 41766@end smallexample
0ce1b118 41767
fc320d37
SL
41768@item Request:
41769@samp{Fgettimeofday,@var{tvptr},@var{tzptr}}
0ce1b118 41770
fc320d37 41771@item Return value:
0ce1b118
CV
41772On success, 0 is returned, -1 otherwise.
41773
fc320d37 41774@item Errors:
0ce1b118
CV
41775
41776@table @code
b383017d 41777@item EINVAL
fc320d37 41778@var{tz} is a non-NULL pointer.
0ce1b118 41779
b383017d 41780@item EFAULT
fc320d37
SL
41781@var{tvptr} and/or @var{tzptr} is an invalid pointer value.
41782@end table
41783
0ce1b118
CV
41784@end table
41785
41786@node isatty
41787@unnumberedsubsubsec isatty
41788@cindex isatty, file-i/o system call
41789
fc320d37
SL
41790@table @asis
41791@item Synopsis:
0ce1b118 41792@smallexample
0ce1b118 41793int isatty(int fd);
fc320d37 41794@end smallexample
0ce1b118 41795
fc320d37
SL
41796@item Request:
41797@samp{Fisatty,@var{fd}}
0ce1b118 41798
fc320d37
SL
41799@item Return value:
41800Returns 1 if @var{fd} refers to the @value{GDBN} console, 0 otherwise.
0ce1b118 41801
fc320d37 41802@item Errors:
0ce1b118
CV
41803
41804@table @code
b383017d 41805@item EINTR
0ce1b118
CV
41806The call was interrupted by the user.
41807@end table
41808
fc320d37
SL
41809@end table
41810
41811Note that the @code{isatty} call is treated as a special case: it returns
418121 to the target if the file descriptor is attached
41813to the @value{GDBN} console, 0 otherwise. Implementing through system calls
41814would require implementing @code{ioctl} and would be more complex than
41815needed.
41816
41817
0ce1b118
CV
41818@node system
41819@unnumberedsubsubsec system
41820@cindex system, file-i/o system call
41821
fc320d37
SL
41822@table @asis
41823@item Synopsis:
0ce1b118 41824@smallexample
0ce1b118 41825int system(const char *command);
fc320d37 41826@end smallexample
0ce1b118 41827
fc320d37
SL
41828@item Request:
41829@samp{Fsystem,@var{commandptr}/@var{len}}
0ce1b118 41830
fc320d37 41831@item Return value:
5600ea19
NS
41832If @var{len} is zero, the return value indicates whether a shell is
41833available. A zero return value indicates a shell is not available.
41834For non-zero @var{len}, the value returned is -1 on error and the
41835return status of the command otherwise. Only the exit status of the
41836command is returned, which is extracted from the host's @code{system}
41837return value by calling @code{WEXITSTATUS(retval)}. In case
41838@file{/bin/sh} could not be executed, 127 is returned.
0ce1b118 41839
fc320d37 41840@item Errors:
0ce1b118
CV
41841
41842@table @code
b383017d 41843@item EINTR
0ce1b118
CV
41844The call was interrupted by the user.
41845@end table
41846
fc320d37
SL
41847@end table
41848
41849@value{GDBN} takes over the full task of calling the necessary host calls
41850to perform the @code{system} call. The return value of @code{system} on
41851the host is simplified before it's returned
41852to the target. Any termination signal information from the child process
41853is discarded, and the return value consists
41854entirely of the exit status of the called command.
41855
41856Due to security concerns, the @code{system} call is by default refused
41857by @value{GDBN}. The user has to allow this call explicitly with the
41858@code{set remote system-call-allowed 1} command.
41859
41860@table @code
41861@item set remote system-call-allowed
41862@kindex set remote system-call-allowed
41863Control whether to allow the @code{system} calls in the File I/O
41864protocol for the remote target. The default is zero (disabled).
41865
41866@item show remote system-call-allowed
41867@kindex show remote system-call-allowed
41868Show whether the @code{system} calls are allowed in the File I/O
41869protocol.
41870@end table
41871
db2e3e2e
BW
41872@node Protocol-specific Representation of Datatypes
41873@subsection Protocol-specific Representation of Datatypes
41874@cindex protocol-specific representation of datatypes, in file-i/o protocol
0ce1b118
CV
41875
41876@menu
79a6e687
BW
41877* Integral Datatypes::
41878* Pointer Values::
41879* Memory Transfer::
0ce1b118
CV
41880* struct stat::
41881* struct timeval::
41882@end menu
41883
79a6e687
BW
41884@node Integral Datatypes
41885@unnumberedsubsubsec Integral Datatypes
0ce1b118
CV
41886@cindex integral datatypes, in file-i/o protocol
41887
fc320d37
SL
41888The integral datatypes used in the system calls are @code{int},
41889@code{unsigned int}, @code{long}, @code{unsigned long},
41890@code{mode_t}, and @code{time_t}.
0ce1b118 41891
fc320d37 41892@code{int}, @code{unsigned int}, @code{mode_t} and @code{time_t} are
0ce1b118
CV
41893implemented as 32 bit values in this protocol.
41894
fc320d37 41895@code{long} and @code{unsigned long} are implemented as 64 bit types.
b383017d 41896
0ce1b118
CV
41897@xref{Limits}, for corresponding MIN and MAX values (similar to those
41898in @file{limits.h}) to allow range checking on host and target.
41899
41900@code{time_t} datatypes are defined as seconds since the Epoch.
41901
41902All integral datatypes transferred as part of a memory read or write of a
41903structured datatype e.g.@: a @code{struct stat} have to be given in big endian
41904byte order.
41905
79a6e687
BW
41906@node Pointer Values
41907@unnumberedsubsubsec Pointer Values
0ce1b118
CV
41908@cindex pointer values, in file-i/o protocol
41909
41910Pointers to target data are transmitted as they are. An exception
41911is made for pointers to buffers for which the length isn't
41912transmitted as part of the function call, namely strings. Strings
41913are transmitted as a pointer/length pair, both as hex values, e.g.@:
41914
41915@smallexample
41916@code{1aaf/12}
41917@end smallexample
41918
41919@noindent
41920which is a pointer to data of length 18 bytes at position 0x1aaf.
41921The length is defined as the full string length in bytes, including
fc320d37
SL
41922the trailing null byte. For example, the string @code{"hello world"}
41923at address 0x123456 is transmitted as
0ce1b118
CV
41924
41925@smallexample
fc320d37 41926@code{123456/d}
0ce1b118
CV
41927@end smallexample
41928
79a6e687
BW
41929@node Memory Transfer
41930@unnumberedsubsubsec Memory Transfer
fc320d37
SL
41931@cindex memory transfer, in file-i/o protocol
41932
41933Structured data which is transferred using a memory read or write (for
db2e3e2e 41934example, a @code{struct stat}) is expected to be in a protocol-specific format
fc320d37
SL
41935with all scalar multibyte datatypes being big endian. Translation to
41936this representation needs to be done both by the target before the @code{F}
41937packet is sent, and by @value{GDBN} before
41938it transfers memory to the target. Transferred pointers to structured
41939data should point to the already-coerced data at any time.
0ce1b118 41940
0ce1b118
CV
41941
41942@node struct stat
41943@unnumberedsubsubsec struct stat
41944@cindex struct stat, in file-i/o protocol
41945
fc320d37
SL
41946The buffer of type @code{struct stat} used by the target and @value{GDBN}
41947is defined as follows:
0ce1b118
CV
41948
41949@smallexample
41950struct stat @{
41951 unsigned int st_dev; /* device */
41952 unsigned int st_ino; /* inode */
41953 mode_t st_mode; /* protection */
41954 unsigned int st_nlink; /* number of hard links */
41955 unsigned int st_uid; /* user ID of owner */
41956 unsigned int st_gid; /* group ID of owner */
41957 unsigned int st_rdev; /* device type (if inode device) */
41958 unsigned long st_size; /* total size, in bytes */
41959 unsigned long st_blksize; /* blocksize for filesystem I/O */
41960 unsigned long st_blocks; /* number of blocks allocated */
41961 time_t st_atime; /* time of last access */
41962 time_t st_mtime; /* time of last modification */
41963 time_t st_ctime; /* time of last change */
41964@};
41965@end smallexample
41966
fc320d37 41967The integral datatypes conform to the definitions given in the
79a6e687 41968appropriate section (see @ref{Integral Datatypes}, for details) so this
0ce1b118
CV
41969structure is of size 64 bytes.
41970
41971The values of several fields have a restricted meaning and/or
41972range of values.
41973
fc320d37 41974@table @code
0ce1b118 41975
fc320d37
SL
41976@item st_dev
41977A value of 0 represents a file, 1 the console.
0ce1b118 41978
fc320d37
SL
41979@item st_ino
41980No valid meaning for the target. Transmitted unchanged.
0ce1b118 41981
fc320d37
SL
41982@item st_mode
41983Valid mode bits are described in @ref{Constants}. Any other
41984bits have currently no meaning for the target.
0ce1b118 41985
fc320d37
SL
41986@item st_uid
41987@itemx st_gid
41988@itemx st_rdev
41989No valid meaning for the target. Transmitted unchanged.
0ce1b118 41990
fc320d37
SL
41991@item st_atime
41992@itemx st_mtime
41993@itemx st_ctime
41994These values have a host and file system dependent
41995accuracy. Especially on Windows hosts, the file system may not
41996support exact timing values.
41997@end table
0ce1b118 41998
fc320d37
SL
41999The target gets a @code{struct stat} of the above representation and is
42000responsible for coercing it to the target representation before
0ce1b118
CV
42001continuing.
42002
fc320d37
SL
42003Note that due to size differences between the host, target, and protocol
42004representations of @code{struct stat} members, these members could eventually
0ce1b118
CV
42005get truncated on the target.
42006
42007@node struct timeval
42008@unnumberedsubsubsec struct timeval
42009@cindex struct timeval, in file-i/o protocol
42010
fc320d37 42011The buffer of type @code{struct timeval} used by the File-I/O protocol
0ce1b118
CV
42012is defined as follows:
42013
42014@smallexample
b383017d 42015struct timeval @{
0ce1b118
CV
42016 time_t tv_sec; /* second */
42017 long tv_usec; /* microsecond */
42018@};
42019@end smallexample
42020
fc320d37 42021The integral datatypes conform to the definitions given in the
79a6e687 42022appropriate section (see @ref{Integral Datatypes}, for details) so this
0ce1b118
CV
42023structure is of size 8 bytes.
42024
42025@node Constants
42026@subsection Constants
42027@cindex constants, in file-i/o protocol
42028
42029The following values are used for the constants inside of the
fc320d37 42030protocol. @value{GDBN} and target are responsible for translating these
0ce1b118
CV
42031values before and after the call as needed.
42032
42033@menu
79a6e687
BW
42034* Open Flags::
42035* mode_t Values::
42036* Errno Values::
42037* Lseek Flags::
0ce1b118
CV
42038* Limits::
42039@end menu
42040
79a6e687
BW
42041@node Open Flags
42042@unnumberedsubsubsec Open Flags
0ce1b118
CV
42043@cindex open flags, in file-i/o protocol
42044
42045All values are given in hexadecimal representation.
42046
42047@smallexample
42048 O_RDONLY 0x0
42049 O_WRONLY 0x1
42050 O_RDWR 0x2
42051 O_APPEND 0x8
42052 O_CREAT 0x200
42053 O_TRUNC 0x400
42054 O_EXCL 0x800
42055@end smallexample
42056
79a6e687
BW
42057@node mode_t Values
42058@unnumberedsubsubsec mode_t Values
0ce1b118
CV
42059@cindex mode_t values, in file-i/o protocol
42060
42061All values are given in octal representation.
42062
42063@smallexample
42064 S_IFREG 0100000
42065 S_IFDIR 040000
42066 S_IRUSR 0400
42067 S_IWUSR 0200
42068 S_IXUSR 0100
42069 S_IRGRP 040
42070 S_IWGRP 020
42071 S_IXGRP 010
42072 S_IROTH 04
42073 S_IWOTH 02
42074 S_IXOTH 01
42075@end smallexample
42076
79a6e687
BW
42077@node Errno Values
42078@unnumberedsubsubsec Errno Values
0ce1b118
CV
42079@cindex errno values, in file-i/o protocol
42080
42081All values are given in decimal representation.
42082
42083@smallexample
42084 EPERM 1
42085 ENOENT 2
42086 EINTR 4
42087 EBADF 9
42088 EACCES 13
42089 EFAULT 14
42090 EBUSY 16
42091 EEXIST 17
42092 ENODEV 19
42093 ENOTDIR 20
42094 EISDIR 21
42095 EINVAL 22
42096 ENFILE 23
42097 EMFILE 24
42098 EFBIG 27
42099 ENOSPC 28
42100 ESPIPE 29
42101 EROFS 30
42102 ENAMETOOLONG 91
42103 EUNKNOWN 9999
42104@end smallexample
42105
fc320d37 42106 @code{EUNKNOWN} is used as a fallback error value if a host system returns
0ce1b118
CV
42107 any error value not in the list of supported error numbers.
42108
79a6e687
BW
42109@node Lseek Flags
42110@unnumberedsubsubsec Lseek Flags
0ce1b118
CV
42111@cindex lseek flags, in file-i/o protocol
42112
42113@smallexample
42114 SEEK_SET 0
42115 SEEK_CUR 1
42116 SEEK_END 2
42117@end smallexample
42118
42119@node Limits
42120@unnumberedsubsubsec Limits
42121@cindex limits, in file-i/o protocol
42122
42123All values are given in decimal representation.
42124
42125@smallexample
42126 INT_MIN -2147483648
42127 INT_MAX 2147483647
42128 UINT_MAX 4294967295
42129 LONG_MIN -9223372036854775808
42130 LONG_MAX 9223372036854775807
42131 ULONG_MAX 18446744073709551615
42132@end smallexample
42133
42134@node File-I/O Examples
42135@subsection File-I/O Examples
42136@cindex file-i/o examples
42137
42138Example sequence of a write call, file descriptor 3, buffer is at target
42139address 0x1234, 6 bytes should be written:
42140
42141@smallexample
42142<- @code{Fwrite,3,1234,6}
42143@emph{request memory read from target}
42144-> @code{m1234,6}
42145<- XXXXXX
42146@emph{return "6 bytes written"}
42147-> @code{F6}
42148@end smallexample
42149
42150Example sequence of a read call, file descriptor 3, buffer is at target
42151address 0x1234, 6 bytes should be read:
42152
42153@smallexample
42154<- @code{Fread,3,1234,6}
42155@emph{request memory write to target}
42156-> @code{X1234,6:XXXXXX}
42157@emph{return "6 bytes read"}
42158-> @code{F6}
42159@end smallexample
42160
42161Example sequence of a read call, call fails on the host due to invalid
fc320d37 42162file descriptor (@code{EBADF}):
0ce1b118
CV
42163
42164@smallexample
42165<- @code{Fread,3,1234,6}
42166-> @code{F-1,9}
42167@end smallexample
42168
c8aa23ab 42169Example sequence of a read call, user presses @kbd{Ctrl-c} before syscall on
0ce1b118
CV
42170host is called:
42171
42172@smallexample
42173<- @code{Fread,3,1234,6}
42174-> @code{F-1,4,C}
42175<- @code{T02}
42176@end smallexample
42177
c8aa23ab 42178Example sequence of a read call, user presses @kbd{Ctrl-c} after syscall on
0ce1b118
CV
42179host is called:
42180
42181@smallexample
42182<- @code{Fread,3,1234,6}
42183-> @code{X1234,6:XXXXXX}
42184<- @code{T02}
42185@end smallexample
42186
cfa9d6d9
DJ
42187@node Library List Format
42188@section Library List Format
42189@cindex library list format, remote protocol
42190
42191On some platforms, a dynamic loader (e.g.@: @file{ld.so}) runs in the
42192same process as your application to manage libraries. In this case,
42193@value{GDBN} can use the loader's symbol table and normal memory
42194operations to maintain a list of shared libraries. On other
42195platforms, the operating system manages loaded libraries.
42196@value{GDBN} can not retrieve the list of currently loaded libraries
42197through memory operations, so it uses the @samp{qXfer:libraries:read}
42198packet (@pxref{qXfer library list read}) instead. The remote stub
42199queries the target's operating system and reports which libraries
42200are loaded.
42201
42202The @samp{qXfer:libraries:read} packet returns an XML document which
42203lists loaded libraries and their offsets. Each library has an
1fddbabb
PA
42204associated name and one or more segment or section base addresses,
42205which report where the library was loaded in memory.
42206
42207For the common case of libraries that are fully linked binaries, the
42208library should have a list of segments. If the target supports
42209dynamic linking of a relocatable object file, its library XML element
42210should instead include a list of allocated sections. The segment or
42211section bases are start addresses, not relocation offsets; they do not
42212depend on the library's link-time base addresses.
cfa9d6d9 42213
9cceb671
DJ
42214@value{GDBN} must be linked with the Expat library to support XML
42215library lists. @xref{Expat}.
42216
cfa9d6d9
DJ
42217A simple memory map, with one loaded library relocated by a single
42218offset, looks like this:
42219
42220@smallexample
42221<library-list>
42222 <library name="/lib/libc.so.6">
42223 <segment address="0x10000000"/>
42224 </library>
42225</library-list>
42226@end smallexample
42227
1fddbabb
PA
42228Another simple memory map, with one loaded library with three
42229allocated sections (.text, .data, .bss), looks like this:
42230
42231@smallexample
42232<library-list>
42233 <library name="sharedlib.o">
42234 <section address="0x10000000"/>
42235 <section address="0x20000000"/>
42236 <section address="0x30000000"/>
42237 </library>
42238</library-list>
42239@end smallexample
42240
cfa9d6d9
DJ
42241The format of a library list is described by this DTD:
42242
42243@smallexample
42244<!-- library-list: Root element with versioning -->
42245<!ELEMENT library-list (library)*>
42246<!ATTLIST library-list version CDATA #FIXED "1.0">
1fddbabb 42247<!ELEMENT library (segment*, section*)>
cfa9d6d9
DJ
42248<!ATTLIST library name CDATA #REQUIRED>
42249<!ELEMENT segment EMPTY>
42250<!ATTLIST segment address CDATA #REQUIRED>
1fddbabb
PA
42251<!ELEMENT section EMPTY>
42252<!ATTLIST section address CDATA #REQUIRED>
cfa9d6d9
DJ
42253@end smallexample
42254
1fddbabb
PA
42255In addition, segments and section descriptors cannot be mixed within a
42256single library element, and you must supply at least one segment or
42257section for each library.
42258
2268b414
JK
42259@node Library List Format for SVR4 Targets
42260@section Library List Format for SVR4 Targets
42261@cindex library list format, remote protocol
42262
42263On SVR4 platforms @value{GDBN} can use the symbol table of a dynamic loader
42264(e.g.@: @file{ld.so}) and normal memory operations to maintain a list of
42265shared libraries. Still a special library list provided by this packet is
42266more efficient for the @value{GDBN} remote protocol.
42267
42268The @samp{qXfer:libraries-svr4:read} packet returns an XML document which lists
42269loaded libraries and their SVR4 linker parameters. For each library on SVR4
42270target, the following parameters are reported:
42271
42272@itemize @minus
42273@item
42274@code{name}, the absolute file name from the @code{l_name} field of
42275@code{struct link_map}.
42276@item
42277@code{lm} with address of @code{struct link_map} used for TLS
42278(Thread Local Storage) access.
42279@item
42280@code{l_addr}, the displacement as read from the field @code{l_addr} of
42281@code{struct link_map}. For prelinked libraries this is not an absolute
42282memory address. It is a displacement of absolute memory address against
42283address the file was prelinked to during the library load.
42284@item
42285@code{l_ld}, which is memory address of the @code{PT_DYNAMIC} segment
42286@end itemize
42287
42288Additionally the single @code{main-lm} attribute specifies address of
42289@code{struct link_map} used for the main executable. This parameter is used
42290for TLS access and its presence is optional.
42291
42292@value{GDBN} must be linked with the Expat library to support XML
42293SVR4 library lists. @xref{Expat}.
42294
42295A simple memory map, with two loaded libraries (which do not use prelink),
42296looks like this:
42297
42298@smallexample
42299<library-list-svr4 version="1.0" main-lm="0xe4f8f8">
42300 <library name="/lib/ld-linux.so.2" lm="0xe4f51c" l_addr="0xe2d000"
42301 l_ld="0xe4eefc"/>
42302 <library name="/lib/libc.so.6" lm="0xe4fbe8" l_addr="0x154000"
db1ff28b 42303 l_ld="0x152350"/>
2268b414
JK
42304</library-list-svr>
42305@end smallexample
42306
42307The format of an SVR4 library list is described by this DTD:
42308
42309@smallexample
42310<!-- library-list-svr4: Root element with versioning -->
42311<!ELEMENT library-list-svr4 (library)*>
db1ff28b
JK
42312<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
42313<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
2268b414 42314<!ELEMENT library EMPTY>
db1ff28b
JK
42315<!ATTLIST library name CDATA #REQUIRED>
42316<!ATTLIST library lm CDATA #REQUIRED>
42317<!ATTLIST library l_addr CDATA #REQUIRED>
42318<!ATTLIST library l_ld CDATA #REQUIRED>
2268b414
JK
42319@end smallexample
42320
79a6e687
BW
42321@node Memory Map Format
42322@section Memory Map Format
68437a39
DJ
42323@cindex memory map format
42324
42325To be able to write into flash memory, @value{GDBN} needs to obtain a
42326memory map from the target. This section describes the format of the
42327memory map.
42328
42329The memory map is obtained using the @samp{qXfer:memory-map:read}
42330(@pxref{qXfer memory map read}) packet and is an XML document that
9cceb671
DJ
42331lists memory regions.
42332
42333@value{GDBN} must be linked with the Expat library to support XML
42334memory maps. @xref{Expat}.
42335
42336The top-level structure of the document is shown below:
68437a39
DJ
42337
42338@smallexample
42339<?xml version="1.0"?>
42340<!DOCTYPE memory-map
42341 PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN"
42342 "http://sourceware.org/gdb/gdb-memory-map.dtd">
42343<memory-map>
42344 region...
42345</memory-map>
42346@end smallexample
42347
42348Each region can be either:
42349
42350@itemize
42351
42352@item
42353A region of RAM starting at @var{addr} and extending for @var{length}
42354bytes from there:
42355
42356@smallexample
42357<memory type="ram" start="@var{addr}" length="@var{length}"/>
42358@end smallexample
42359
42360
42361@item
42362A region of read-only memory:
42363
42364@smallexample
42365<memory type="rom" start="@var{addr}" length="@var{length}"/>
42366@end smallexample
42367
42368
42369@item
42370A region of flash memory, with erasure blocks @var{blocksize}
42371bytes in length:
42372
42373@smallexample
42374<memory type="flash" start="@var{addr}" length="@var{length}">
42375 <property name="blocksize">@var{blocksize}</property>
42376</memory>
42377@end smallexample
42378
42379@end itemize
42380
42381Regions must not overlap. @value{GDBN} assumes that areas of memory not covered
42382by the memory map are RAM, and uses the ordinary @samp{M} and @samp{X}
42383packets to write to addresses in such ranges.
42384
42385The formal DTD for memory map format is given below:
42386
42387@smallexample
42388<!-- ................................................... -->
42389<!-- Memory Map XML DTD ................................ -->
42390<!-- File: memory-map.dtd .............................. -->
42391<!-- .................................... .............. -->
42392<!-- memory-map.dtd -->
42393<!-- memory-map: Root element with versioning -->
5f1ca24a 42394<!ELEMENT memory-map (memory)*>
68437a39 42395<!ATTLIST memory-map version CDATA #FIXED "1.0.0">
5f1ca24a 42396<!ELEMENT memory (property)*>
68437a39
DJ
42397<!-- memory: Specifies a memory region,
42398 and its type, or device. -->
5f1ca24a 42399<!ATTLIST memory type (ram|rom|flash) #REQUIRED
68437a39 42400 start CDATA #REQUIRED
5f1ca24a 42401 length CDATA #REQUIRED>
68437a39
DJ
42402<!-- property: Generic attribute tag -->
42403<!ELEMENT property (#PCDATA | property)*>
5f1ca24a 42404<!ATTLIST property name (blocksize) #REQUIRED>
68437a39
DJ
42405@end smallexample
42406
dc146f7c
VP
42407@node Thread List Format
42408@section Thread List Format
42409@cindex thread list format
42410
42411To efficiently update the list of threads and their attributes,
42412@value{GDBN} issues the @samp{qXfer:threads:read} packet
42413(@pxref{qXfer threads read}) and obtains the XML document with
42414the following structure:
42415
42416@smallexample
42417<?xml version="1.0"?>
42418<threads>
79efa585 42419 <thread id="id" core="0" name="name">
dc146f7c
VP
42420 ... description ...
42421 </thread>
42422</threads>
42423@end smallexample
42424
42425Each @samp{thread} element must have the @samp{id} attribute that
42426identifies the thread (@pxref{thread-id syntax}). The
42427@samp{core} attribute, if present, specifies which processor core
79efa585
SM
42428the thread was last executing on. The @samp{name} attribute, if
42429present, specifies the human-readable name of the thread. The content
42430of the of @samp{thread} element is interpreted as human-readable
f2ff95c5
KB
42431auxiliary information. The @samp{handle} attribute, if present,
42432is a hex encoded representation of the thread handle.
42433
dc146f7c 42434
b3b9301e
PA
42435@node Traceframe Info Format
42436@section Traceframe Info Format
42437@cindex traceframe info format
42438
42439To be able to know which objects in the inferior can be examined when
42440inspecting a tracepoint hit, @value{GDBN} needs to obtain the list of
42441memory ranges, registers and trace state variables that have been
42442collected in a traceframe.
42443
42444This list is obtained using the @samp{qXfer:traceframe-info:read}
42445(@pxref{qXfer traceframe info read}) packet and is an XML document.
42446
42447@value{GDBN} must be linked with the Expat library to support XML
42448traceframe info discovery. @xref{Expat}.
42449
42450The top-level structure of the document is shown below:
42451
42452@smallexample
42453<?xml version="1.0"?>
42454<!DOCTYPE traceframe-info
42455 PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN"
42456 "http://sourceware.org/gdb/gdb-traceframe-info.dtd">
42457<traceframe-info>
42458 block...
42459</traceframe-info>
42460@end smallexample
42461
42462Each traceframe block can be either:
42463
42464@itemize
42465
42466@item
42467A region of collected memory starting at @var{addr} and extending for
42468@var{length} bytes from there:
42469
42470@smallexample
42471<memory start="@var{addr}" length="@var{length}"/>
42472@end smallexample
42473
28a93511
YQ
42474@item
42475A block indicating trace state variable numbered @var{number} has been
42476collected:
42477
42478@smallexample
42479<tvar id="@var{number}"/>
42480@end smallexample
42481
b3b9301e
PA
42482@end itemize
42483
42484The formal DTD for the traceframe info format is given below:
42485
42486@smallexample
28a93511 42487<!ELEMENT traceframe-info (memory | tvar)* >
b3b9301e
PA
42488<!ATTLIST traceframe-info version CDATA #FIXED "1.0">
42489
42490<!ELEMENT memory EMPTY>
42491<!ATTLIST memory start CDATA #REQUIRED
42492 length CDATA #REQUIRED>
28a93511
YQ
42493<!ELEMENT tvar>
42494<!ATTLIST tvar id CDATA #REQUIRED>
b3b9301e
PA
42495@end smallexample
42496
2ae8c8e7
MM
42497@node Branch Trace Format
42498@section Branch Trace Format
42499@cindex branch trace format
42500
42501In order to display the branch trace of an inferior thread,
42502@value{GDBN} needs to obtain the list of branches. This list is
42503represented as list of sequential code blocks that are connected via
42504branches. The code in each block has been executed sequentially.
42505
42506This list is obtained using the @samp{qXfer:btrace:read}
42507(@pxref{qXfer btrace read}) packet and is an XML document.
42508
42509@value{GDBN} must be linked with the Expat library to support XML
42510traceframe info discovery. @xref{Expat}.
42511
42512The top-level structure of the document is shown below:
42513
42514@smallexample
42515<?xml version="1.0"?>
42516<!DOCTYPE btrace
42517 PUBLIC "+//IDN gnu.org//DTD GDB Branch Trace V1.0//EN"
42518 "http://sourceware.org/gdb/gdb-btrace.dtd">
42519<btrace>
42520 block...
42521</btrace>
42522@end smallexample
42523
42524@itemize
42525
42526@item
42527A block of sequentially executed instructions starting at @var{begin}
42528and ending at @var{end}:
42529
42530@smallexample
42531<block begin="@var{begin}" end="@var{end}"/>
42532@end smallexample
42533
42534@end itemize
42535
42536The formal DTD for the branch trace format is given below:
42537
42538@smallexample
b20a6524 42539<!ELEMENT btrace (block* | pt) >
2ae8c8e7
MM
42540<!ATTLIST btrace version CDATA #FIXED "1.0">
42541
42542<!ELEMENT block EMPTY>
42543<!ATTLIST block begin CDATA #REQUIRED
42544 end CDATA #REQUIRED>
b20a6524
MM
42545
42546<!ELEMENT pt (pt-config?, raw?)>
42547
42548<!ELEMENT pt-config (cpu?)>
42549
42550<!ELEMENT cpu EMPTY>
42551<!ATTLIST cpu vendor CDATA #REQUIRED
42552 family CDATA #REQUIRED
42553 model CDATA #REQUIRED
42554 stepping CDATA #REQUIRED>
42555
42556<!ELEMENT raw (#PCDATA)>
2ae8c8e7
MM
42557@end smallexample
42558
f4abbc16
MM
42559@node Branch Trace Configuration Format
42560@section Branch Trace Configuration Format
42561@cindex branch trace configuration format
42562
42563For each inferior thread, @value{GDBN} can obtain the branch trace
42564configuration using the @samp{qXfer:btrace-conf:read}
42565(@pxref{qXfer btrace-conf read}) packet.
42566
42567The configuration describes the branch trace format and configuration
d33501a5
MM
42568settings for that format. The following information is described:
42569
42570@table @code
42571@item bts
42572This thread uses the @dfn{Branch Trace Store} (@acronym{BTS}) format.
42573@table @code
42574@item size
42575The size of the @acronym{BTS} ring buffer in bytes.
42576@end table
b20a6524 42577@item pt
bc504a31 42578This thread uses the @dfn{Intel Processor Trace} (@acronym{Intel
b20a6524
MM
42579PT}) format.
42580@table @code
42581@item size
bc504a31 42582The size of the @acronym{Intel PT} ring buffer in bytes.
b20a6524 42583@end table
d33501a5 42584@end table
f4abbc16
MM
42585
42586@value{GDBN} must be linked with the Expat library to support XML
42587branch trace configuration discovery. @xref{Expat}.
42588
42589The formal DTD for the branch trace configuration format is given below:
42590
42591@smallexample
b20a6524 42592<!ELEMENT btrace-conf (bts?, pt?)>
f4abbc16
MM
42593<!ATTLIST btrace-conf version CDATA #FIXED "1.0">
42594
42595<!ELEMENT bts EMPTY>
d33501a5 42596<!ATTLIST bts size CDATA #IMPLIED>
b20a6524
MM
42597
42598<!ELEMENT pt EMPTY>
42599<!ATTLIST pt size CDATA #IMPLIED>
f4abbc16
MM
42600@end smallexample
42601
f418dd93
DJ
42602@include agentexpr.texi
42603
23181151
DJ
42604@node Target Descriptions
42605@appendix Target Descriptions
42606@cindex target descriptions
42607
23181151
DJ
42608One of the challenges of using @value{GDBN} to debug embedded systems
42609is that there are so many minor variants of each processor
42610architecture in use. It is common practice for vendors to start with
eb17f351 42611a standard processor core --- ARM, PowerPC, or @acronym{MIPS}, for example ---
23181151
DJ
42612and then make changes to adapt it to a particular market niche. Some
42613architectures have hundreds of variants, available from dozens of
42614vendors. This leads to a number of problems:
42615
42616@itemize @bullet
42617@item
42618With so many different customized processors, it is difficult for
42619the @value{GDBN} maintainers to keep up with the changes.
42620@item
42621Since individual variants may have short lifetimes or limited
42622audiences, it may not be worthwhile to carry information about every
42623variant in the @value{GDBN} source tree.
42624@item
42625When @value{GDBN} does support the architecture of the embedded system
42626at hand, the task of finding the correct architecture name to give the
42627@command{set architecture} command can be error-prone.
42628@end itemize
42629
42630To address these problems, the @value{GDBN} remote protocol allows a
42631target system to not only identify itself to @value{GDBN}, but to
42632actually describe its own features. This lets @value{GDBN} support
42633processor variants it has never seen before --- to the extent that the
42634descriptions are accurate, and that @value{GDBN} understands them.
42635
9cceb671
DJ
42636@value{GDBN} must be linked with the Expat library to support XML
42637target descriptions. @xref{Expat}.
123dc839 42638
23181151
DJ
42639@menu
42640* Retrieving Descriptions:: How descriptions are fetched from a target.
42641* Target Description Format:: The contents of a target description.
123dc839
DJ
42642* Predefined Target Types:: Standard types available for target
42643 descriptions.
81516450 42644* Enum Target Types:: How to define enum target types.
123dc839 42645* Standard Target Features:: Features @value{GDBN} knows about.
23181151
DJ
42646@end menu
42647
42648@node Retrieving Descriptions
42649@section Retrieving Descriptions
42650
42651Target descriptions can be read from the target automatically, or
42652specified by the user manually. The default behavior is to read the
42653description from the target. @value{GDBN} retrieves it via the remote
42654protocol using @samp{qXfer} requests (@pxref{General Query Packets,
42655qXfer}). The @var{annex} in the @samp{qXfer} packet will be
42656@samp{target.xml}. The contents of the @samp{target.xml} annex are an
42657XML document, of the form described in @ref{Target Description
42658Format}.
42659
42660Alternatively, you can specify a file to read for the target description.
42661If a file is set, the target will not be queried. The commands to
42662specify a file are:
42663
42664@table @code
42665@cindex set tdesc filename
42666@item set tdesc filename @var{path}
42667Read the target description from @var{path}.
42668
42669@cindex unset tdesc filename
42670@item unset tdesc filename
42671Do not read the XML target description from a file. @value{GDBN}
42672will use the description supplied by the current target.
42673
42674@cindex show tdesc filename
42675@item show tdesc filename
42676Show the filename to read for a target description, if any.
42677@end table
42678
42679
42680@node Target Description Format
42681@section Target Description Format
42682@cindex target descriptions, XML format
42683
42684A target description annex is an @uref{http://www.w3.org/XML/, XML}
42685document which complies with the Document Type Definition provided in
42686the @value{GDBN} sources in @file{gdb/features/gdb-target.dtd}. This
42687means you can use generally available tools like @command{xmllint} to
42688check that your feature descriptions are well-formed and valid.
42689However, to help people unfamiliar with XML write descriptions for
42690their targets, we also describe the grammar here.
42691
123dc839
DJ
42692Target descriptions can identify the architecture of the remote target
42693and (for some architectures) provide information about custom register
08d16641
PA
42694sets. They can also identify the OS ABI of the remote target.
42695@value{GDBN} can use this information to autoconfigure for your
123dc839 42696target, or to warn you if you connect to an unsupported target.
23181151
DJ
42697
42698Here is a simple target description:
42699
123dc839 42700@smallexample
1780a0ed 42701<target version="1.0">
23181151
DJ
42702 <architecture>i386:x86-64</architecture>
42703</target>
123dc839 42704@end smallexample
23181151
DJ
42705
42706@noindent
42707This minimal description only says that the target uses
42708the x86-64 architecture.
42709
123dc839
DJ
42710A target description has the following overall form, with [ ] marking
42711optional elements and @dots{} marking repeatable elements. The elements
42712are explained further below.
23181151 42713
123dc839 42714@smallexample
23181151
DJ
42715<?xml version="1.0"?>
42716<!DOCTYPE target SYSTEM "gdb-target.dtd">
1780a0ed 42717<target version="1.0">
123dc839 42718 @r{[}@var{architecture}@r{]}
08d16641 42719 @r{[}@var{osabi}@r{]}
e35359c5 42720 @r{[}@var{compatible}@r{]}
123dc839 42721 @r{[}@var{feature}@dots{}@r{]}
23181151 42722</target>
123dc839 42723@end smallexample
23181151
DJ
42724
42725@noindent
42726The description is generally insensitive to whitespace and line
42727breaks, under the usual common-sense rules. The XML version
42728declaration and document type declaration can generally be omitted
42729(@value{GDBN} does not require them), but specifying them may be
1780a0ed
DJ
42730useful for XML validation tools. The @samp{version} attribute for
42731@samp{<target>} may also be omitted, but we recommend
42732including it; if future versions of @value{GDBN} use an incompatible
42733revision of @file{gdb-target.dtd}, they will detect and report
42734the version mismatch.
23181151 42735
108546a0
DJ
42736@subsection Inclusion
42737@cindex target descriptions, inclusion
42738@cindex XInclude
42739@ifnotinfo
42740@cindex <xi:include>
42741@end ifnotinfo
42742
42743It can sometimes be valuable to split a target description up into
42744several different annexes, either for organizational purposes, or to
42745share files between different possible target descriptions. You can
42746divide a description into multiple files by replacing any element of
42747the target description with an inclusion directive of the form:
42748
123dc839 42749@smallexample
108546a0 42750<xi:include href="@var{document}"/>
123dc839 42751@end smallexample
108546a0
DJ
42752
42753@noindent
42754When @value{GDBN} encounters an element of this form, it will retrieve
42755the named XML @var{document}, and replace the inclusion directive with
42756the contents of that document. If the current description was read
42757using @samp{qXfer}, then so will be the included document;
42758@var{document} will be interpreted as the name of an annex. If the
42759current description was read from a file, @value{GDBN} will look for
42760@var{document} as a file in the same directory where it found the
42761original description.
42762
123dc839
DJ
42763@subsection Architecture
42764@cindex <architecture>
42765
42766An @samp{<architecture>} element has this form:
42767
42768@smallexample
42769 <architecture>@var{arch}</architecture>
42770@end smallexample
42771
e35359c5
UW
42772@var{arch} is one of the architectures from the set accepted by
42773@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
123dc839 42774
08d16641
PA
42775@subsection OS ABI
42776@cindex @code{<osabi>}
42777
42778This optional field was introduced in @value{GDBN} version 7.0.
42779Previous versions of @value{GDBN} ignore it.
42780
42781An @samp{<osabi>} element has this form:
42782
42783@smallexample
42784 <osabi>@var{abi-name}</osabi>
42785@end smallexample
42786
42787@var{abi-name} is an OS ABI name from the same selection accepted by
42788@w{@code{set osabi}} (@pxref{ABI, ,Configuring the Current ABI}).
42789
e35359c5
UW
42790@subsection Compatible Architecture
42791@cindex @code{<compatible>}
42792
42793This optional field was introduced in @value{GDBN} version 7.0.
42794Previous versions of @value{GDBN} ignore it.
42795
42796A @samp{<compatible>} element has this form:
42797
42798@smallexample
42799 <compatible>@var{arch}</compatible>
42800@end smallexample
42801
42802@var{arch} is one of the architectures from the set accepted by
42803@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
42804
42805A @samp{<compatible>} element is used to specify that the target
42806is able to run binaries in some other than the main target architecture
42807given by the @samp{<architecture>} element. For example, on the
42808Cell Broadband Engine, the main architecture is @code{powerpc:common}
42809or @code{powerpc:common64}, but the system is able to run binaries
42810in the @code{spu} architecture as well. The way to describe this
42811capability with @samp{<compatible>} is as follows:
42812
42813@smallexample
42814 <architecture>powerpc:common</architecture>
42815 <compatible>spu</compatible>
42816@end smallexample
42817
123dc839
DJ
42818@subsection Features
42819@cindex <feature>
42820
42821Each @samp{<feature>} describes some logical portion of the target
42822system. Features are currently used to describe available CPU
42823registers and the types of their contents. A @samp{<feature>} element
42824has this form:
42825
42826@smallexample
42827<feature name="@var{name}">
42828 @r{[}@var{type}@dots{}@r{]}
42829 @var{reg}@dots{}
42830</feature>
42831@end smallexample
42832
42833@noindent
42834Each feature's name should be unique within the description. The name
42835of a feature does not matter unless @value{GDBN} has some special
42836knowledge of the contents of that feature; if it does, the feature
42837should have its standard name. @xref{Standard Target Features}.
42838
42839@subsection Types
42840
42841Any register's value is a collection of bits which @value{GDBN} must
42842interpret. The default interpretation is a two's complement integer,
42843but other types can be requested by name in the register description.
42844Some predefined types are provided by @value{GDBN} (@pxref{Predefined
81516450
DE
42845Target Types}), and the description can define additional composite
42846and enum types.
123dc839
DJ
42847
42848Each type element must have an @samp{id} attribute, which gives
42849a unique (within the containing @samp{<feature>}) name to the type.
42850Types must be defined before they are used.
42851
42852@cindex <vector>
42853Some targets offer vector registers, which can be treated as arrays
42854of scalar elements. These types are written as @samp{<vector>} elements,
42855specifying the array element type, @var{type}, and the number of elements,
42856@var{count}:
42857
42858@smallexample
42859<vector id="@var{id}" type="@var{type}" count="@var{count}"/>
42860@end smallexample
42861
42862@cindex <union>
42863If a register's value is usefully viewed in multiple ways, define it
42864with a union type containing the useful representations. The
42865@samp{<union>} element contains one or more @samp{<field>} elements,
42866each of which has a @var{name} and a @var{type}:
42867
42868@smallexample
42869<union id="@var{id}">
42870 <field name="@var{name}" type="@var{type}"/>
42871 @dots{}
42872</union>
42873@end smallexample
42874
f5dff777 42875@cindex <struct>
81516450 42876@cindex <flags>
f5dff777 42877If a register's value is composed from several separate values, define
81516450
DE
42878it with either a structure type or a flags type.
42879A flags type may only contain bitfields.
42880A structure type may either contain only bitfields or contain no bitfields.
42881If the value contains only bitfields, its total size in bytes must be
42882specified.
42883
42884Non-bitfield values have a @var{name} and @var{type}.
f5dff777
DJ
42885
42886@smallexample
81516450
DE
42887<struct id="@var{id}">
42888 <field name="@var{name}" type="@var{type}"/>
f5dff777
DJ
42889 @dots{}
42890</struct>
42891@end smallexample
42892
81516450
DE
42893Both @var{name} and @var{type} values are required.
42894No implicit padding is added.
42895
42896Bitfield values have a @var{name}, @var{start}, @var{end} and @var{type}.
f5dff777
DJ
42897
42898@smallexample
81516450
DE
42899<struct id="@var{id}" size="@var{size}">
42900 <field name="@var{name}" start="@var{start}" end="@var{end}" type="@var{type}"/>
f5dff777
DJ
42901 @dots{}
42902</struct>
42903@end smallexample
42904
f5dff777
DJ
42905@smallexample
42906<flags id="@var{id}" size="@var{size}">
81516450 42907 <field name="@var{name}" start="@var{start}" end="@var{end}" type="@var{type}"/>
f5dff777
DJ
42908 @dots{}
42909</flags>
42910@end smallexample
42911
81516450
DE
42912The @var{name} value is required.
42913Bitfield values may be named with the empty string, @samp{""},
42914in which case the field is ``filler'' and its value is not printed.
42915Not all bits need to be specified, so ``filler'' fields are optional.
42916
ee8da4b8
DE
42917The @var{start} and @var{end} values are required, and @var{type}
42918is optional.
81516450
DE
42919The field's @var{start} must be less than or equal to its @var{end},
42920and zero represents the least significant bit.
81516450 42921
ee8da4b8
DE
42922The default value of @var{type} is @code{bool} for single bit fields,
42923and an unsigned integer otherwise.
81516450
DE
42924
42925Which to choose? Structures or flags?
42926
42927Registers defined with @samp{flags} have these advantages over
42928defining them with @samp{struct}:
42929
42930@itemize @bullet
42931@item
42932Arithmetic may be performed on them as if they were integers.
42933@item
42934They are printed in a more readable fashion.
42935@end itemize
42936
42937Registers defined with @samp{struct} have one advantage over
42938defining them with @samp{flags}:
42939
42940@itemize @bullet
42941@item
42942One can fetch individual fields like in @samp{C}.
42943
42944@smallexample
42945(gdb) print $my_struct_reg.field3
42946$1 = 42
42947@end smallexample
42948
42949@end itemize
42950
123dc839
DJ
42951@subsection Registers
42952@cindex <reg>
42953
42954Each register is represented as an element with this form:
42955
42956@smallexample
42957<reg name="@var{name}"
42958 bitsize="@var{size}"
42959 @r{[}regnum="@var{num}"@r{]}
42960 @r{[}save-restore="@var{save-restore}"@r{]}
42961 @r{[}type="@var{type}"@r{]}
42962 @r{[}group="@var{group}"@r{]}/>
42963@end smallexample
42964
42965@noindent
42966The components are as follows:
42967
42968@table @var
42969
42970@item name
42971The register's name; it must be unique within the target description.
42972
42973@item bitsize
42974The register's size, in bits.
42975
42976@item regnum
42977The register's number. If omitted, a register's number is one greater
42978than that of the previous register (either in the current feature or in
177b42fe 42979a preceding feature); the first register in the target description
123dc839
DJ
42980defaults to zero. This register number is used to read or write
42981the register; e.g.@: it is used in the remote @code{p} and @code{P}
42982packets, and registers appear in the @code{g} and @code{G} packets
42983in order of increasing register number.
42984
42985@item save-restore
42986Whether the register should be preserved across inferior function
42987calls; this must be either @code{yes} or @code{no}. The default is
42988@code{yes}, which is appropriate for most registers except for
42989some system control registers; this is not related to the target's
42990ABI.
42991
42992@item type
697aa1b7 42993The type of the register. It may be a predefined type, a type
123dc839
DJ
42994defined in the current feature, or one of the special types @code{int}
42995and @code{float}. @code{int} is an integer type of the correct size
42996for @var{bitsize}, and @code{float} is a floating point type (in the
42997architecture's normal floating point format) of the correct size for
42998@var{bitsize}. The default is @code{int}.
42999
43000@item group
cef0f868
SH
43001The register group to which this register belongs. It can be one of the
43002standard register groups @code{general}, @code{float}, @code{vector} or an
43003arbitrary string. Group names should be limited to alphanumeric characters.
43004If a group name is made up of multiple words the words may be separated by
43005hyphens; e.g.@: @code{special-group} or @code{ultra-special-group}. If no
43006@var{group} is specified, @value{GDBN} will not display the register in
43007@code{info registers}.
123dc839
DJ
43008
43009@end table
43010
43011@node Predefined Target Types
43012@section Predefined Target Types
43013@cindex target descriptions, predefined types
43014
43015Type definitions in the self-description can build up composite types
43016from basic building blocks, but can not define fundamental types. Instead,
43017standard identifiers are provided by @value{GDBN} for the fundamental
43018types. The currently supported types are:
43019
43020@table @code
43021
81516450
DE
43022@item bool
43023Boolean type, occupying a single bit.
43024
123dc839
DJ
43025@item int8
43026@itemx int16
d1908f2d 43027@itemx int24
123dc839
DJ
43028@itemx int32
43029@itemx int64
7cc46491 43030@itemx int128
123dc839
DJ
43031Signed integer types holding the specified number of bits.
43032
43033@item uint8
43034@itemx uint16
d1908f2d 43035@itemx uint24
123dc839
DJ
43036@itemx uint32
43037@itemx uint64
7cc46491 43038@itemx uint128
123dc839
DJ
43039Unsigned integer types holding the specified number of bits.
43040
43041@item code_ptr
43042@itemx data_ptr
43043Pointers to unspecified code and data. The program counter and
43044any dedicated return address register may be marked as code
43045pointers; printing a code pointer converts it into a symbolic
43046address. The stack pointer and any dedicated address registers
43047may be marked as data pointers.
43048
6e3bbd1a
PB
43049@item ieee_single
43050Single precision IEEE floating point.
43051
43052@item ieee_double
43053Double precision IEEE floating point.
43054
123dc839
DJ
43055@item arm_fpa_ext
43056The 12-byte extended precision format used by ARM FPA registers.
43057
075b51b7
L
43058@item i387_ext
43059The 10-byte extended precision format used by x87 registers.
43060
43061@item i386_eflags
4306232bit @sc{eflags} register used by x86.
43063
43064@item i386_mxcsr
4306532bit @sc{mxcsr} register used by x86.
43066
123dc839
DJ
43067@end table
43068
81516450
DE
43069@node Enum Target Types
43070@section Enum Target Types
43071@cindex target descriptions, enum types
43072
43073Enum target types are useful in @samp{struct} and @samp{flags}
43074register descriptions. @xref{Target Description Format}.
43075
43076Enum types have a name, size and a list of name/value pairs.
43077
43078@smallexample
43079<enum id="@var{id}" size="@var{size}">
43080 <evalue name="@var{name}" value="@var{value}"/>
43081 @dots{}
43082</enum>
43083@end smallexample
43084
43085Enums must be defined before they are used.
43086
43087@smallexample
43088<enum id="levels_type" size="4">
43089 <evalue name="low" value="0"/>
43090 <evalue name="high" value="1"/>
43091</enum>
43092<flags id="flags_type" size="4">
43093 <field name="X" start="0"/>
43094 <field name="LEVEL" start="1" end="1" type="levels_type"/>
43095</flags>
43096<reg name="flags" bitsize="32" type="flags_type"/>
43097@end smallexample
43098
43099Given that description, a value of 3 for the @samp{flags} register
43100would be printed as:
43101
43102@smallexample
43103(gdb) info register flags
43104flags 0x3 [ X LEVEL=high ]
43105@end smallexample
43106
123dc839
DJ
43107@node Standard Target Features
43108@section Standard Target Features
43109@cindex target descriptions, standard features
43110
43111A target description must contain either no registers or all the
43112target's registers. If the description contains no registers, then
43113@value{GDBN} will assume a default register layout, selected based on
43114the architecture. If the description contains any registers, the
43115default layout will not be used; the standard registers must be
43116described in the target description, in such a way that @value{GDBN}
43117can recognize them.
43118
43119This is accomplished by giving specific names to feature elements
43120which contain standard registers. @value{GDBN} will look for features
43121with those names and verify that they contain the expected registers;
43122if any known feature is missing required registers, or if any required
43123feature is missing, @value{GDBN} will reject the target
43124description. You can add additional registers to any of the
43125standard features --- @value{GDBN} will display them just as if
43126they were added to an unrecognized feature.
43127
43128This section lists the known features and their expected contents.
43129Sample XML documents for these features are included in the
43130@value{GDBN} source tree, in the directory @file{gdb/features}.
43131
43132Names recognized by @value{GDBN} should include the name of the
43133company or organization which selected the name, and the overall
43134architecture to which the feature applies; so e.g.@: the feature
43135containing ARM core registers is named @samp{org.gnu.gdb.arm.core}.
43136
ff6f572f
DJ
43137The names of registers are not case sensitive for the purpose
43138of recognizing standard features, but @value{GDBN} will only display
43139registers using the capitalization used in the description.
43140
e9c17194 43141@menu
430ed3f0 43142* AArch64 Features::
ad0a504f 43143* ARC Features::
e9c17194 43144* ARM Features::
3bb8d5c3 43145* i386 Features::
164224e9 43146* MicroBlaze Features::
1e26b4f8 43147* MIPS Features::
e9c17194 43148* M68K Features::
a28d8e50 43149* NDS32 Features::
a1217d97 43150* Nios II Features::
a994fec4 43151* OpenRISC 1000 Features::
1e26b4f8 43152* PowerPC Features::
b5ffee31 43153* RISC-V Features::
4ac33720 43154* S/390 and System z Features::
3f7b46f2 43155* Sparc Features::
224bbe49 43156* TIC6x Features::
e9c17194
VP
43157@end menu
43158
43159
430ed3f0
MS
43160@node AArch64 Features
43161@subsection AArch64 Features
43162@cindex target descriptions, AArch64 features
43163
43164The @samp{org.gnu.gdb.aarch64.core} feature is required for AArch64
43165targets. It should contain registers @samp{x0} through @samp{x30},
43166@samp{sp}, @samp{pc}, and @samp{cpsr}.
43167
43168The @samp{org.gnu.gdb.aarch64.fpu} feature is optional. If present,
43169it should contain registers @samp{v0} through @samp{v31}, @samp{fpsr},
43170and @samp{fpcr}.
43171
95228a0d
AH
43172The @samp{org.gnu.gdb.aarch64.sve} feature is optional. If present,
43173it should contain registers @samp{z0} through @samp{z31}, @samp{p0}
43174through @samp{p15}, @samp{ffr} and @samp{vg}.
43175
6dc0ebde
AH
43176The @samp{org.gnu.gdb.aarch64.pauth} feature is optional. If present,
43177it should contain registers @samp{pauth_dmask} and @samp{pauth_cmask}.
43178
ad0a504f
AK
43179@node ARC Features
43180@subsection ARC Features
43181@cindex target descriptions, ARC Features
43182
43183ARC processors are highly configurable, so even core registers and their number
43184are not completely predetermined. In addition flags and PC registers which are
43185important to @value{GDBN} are not ``core'' registers in ARC. It is required
43186that one of the core registers features is present.
43187@samp{org.gnu.gdb.arc.aux-minimal} feature is mandatory.
43188
43189The @samp{org.gnu.gdb.arc.core.v2} feature is required for ARC EM and ARC HS
43190targets with a normal register file. It should contain registers @samp{r0}
43191through @samp{r25}, @samp{gp}, @samp{fp}, @samp{sp}, @samp{r30}, @samp{blink},
43192@samp{lp_count} and @samp{pcl}. This feature may contain register @samp{ilink}
43193and any of extension core registers @samp{r32} through @samp{r59/acch}.
43194@samp{ilink} and extension core registers are not available to read/write, when
43195debugging GNU/Linux applications, thus @samp{ilink} is made optional.
43196
43197The @samp{org.gnu.gdb.arc.core-reduced.v2} feature is required for ARC EM and
43198ARC HS targets with a reduced register file. It should contain registers
43199@samp{r0} through @samp{r3}, @samp{r10} through @samp{r15}, @samp{gp},
43200@samp{fp}, @samp{sp}, @samp{r30}, @samp{blink}, @samp{lp_count} and @samp{pcl}.
43201This feature may contain register @samp{ilink} and any of extension core
43202registers @samp{r32} through @samp{r59/acch}.
43203
43204The @samp{org.gnu.gdb.arc.core.arcompact} feature is required for ARCompact
43205targets with a normal register file. It should contain registers @samp{r0}
43206through @samp{r25}, @samp{gp}, @samp{fp}, @samp{sp}, @samp{r30}, @samp{blink},
43207@samp{lp_count} and @samp{pcl}. This feature may contain registers
43208@samp{ilink1}, @samp{ilink2} and any of extension core registers @samp{r32}
43209through @samp{r59/acch}. @samp{ilink1} and @samp{ilink2} and extension core
43210registers are not available when debugging GNU/Linux applications. The only
43211difference with @samp{org.gnu.gdb.arc.core.v2} feature is in the names of
43212@samp{ilink1} and @samp{ilink2} registers and that @samp{r30} is mandatory in
43213ARC v2, but @samp{ilink2} is optional on ARCompact.
43214
43215The @samp{org.gnu.gdb.arc.aux-minimal} feature is required for all ARC
43216targets. It should contain registers @samp{pc} and @samp{status32}.
43217
e9c17194 43218@node ARM Features
123dc839
DJ
43219@subsection ARM Features
43220@cindex target descriptions, ARM features
43221
9779414d
DJ
43222The @samp{org.gnu.gdb.arm.core} feature is required for non-M-profile
43223ARM targets.
123dc839
DJ
43224It should contain registers @samp{r0} through @samp{r13}, @samp{sp},
43225@samp{lr}, @samp{pc}, and @samp{cpsr}.
43226
9779414d
DJ
43227For M-profile targets (e.g. Cortex-M3), the @samp{org.gnu.gdb.arm.core}
43228feature is replaced by @samp{org.gnu.gdb.arm.m-profile}. It should contain
43229registers @samp{r0} through @samp{r13}, @samp{sp}, @samp{lr}, @samp{pc},
43230and @samp{xpsr}.
43231
123dc839
DJ
43232The @samp{org.gnu.gdb.arm.fpa} feature is optional. If present, it
43233should contain registers @samp{f0} through @samp{f7} and @samp{fps}.
43234
ff6f572f
DJ
43235The @samp{org.gnu.gdb.xscale.iwmmxt} feature is optional. If present,
43236it should contain at least registers @samp{wR0} through @samp{wR15} and
43237@samp{wCGR0} through @samp{wCGR3}. The @samp{wCID}, @samp{wCon},
43238@samp{wCSSF}, and @samp{wCASF} registers are optional.
23181151 43239
58d6951d
DJ
43240The @samp{org.gnu.gdb.arm.vfp} feature is optional. If present, it
43241should contain at least registers @samp{d0} through @samp{d15}. If
43242they are present, @samp{d16} through @samp{d31} should also be included.
43243@value{GDBN} will synthesize the single-precision registers from
43244halves of the double-precision registers.
43245
43246The @samp{org.gnu.gdb.arm.neon} feature is optional. It does not
43247need to contain registers; it instructs @value{GDBN} to display the
43248VFP double-precision registers as vectors and to synthesize the
43249quad-precision registers from pairs of double-precision registers.
43250If this feature is present, @samp{org.gnu.gdb.arm.vfp} must also
43251be present and include 32 double-precision registers.
43252
3bb8d5c3
L
43253@node i386 Features
43254@subsection i386 Features
43255@cindex target descriptions, i386 features
43256
43257The @samp{org.gnu.gdb.i386.core} feature is required for i386/amd64
43258targets. It should describe the following registers:
43259
43260@itemize @minus
43261@item
43262@samp{eax} through @samp{edi} plus @samp{eip} for i386
43263@item
43264@samp{rax} through @samp{r15} plus @samp{rip} for amd64
43265@item
43266@samp{eflags}, @samp{cs}, @samp{ss}, @samp{ds}, @samp{es},
43267@samp{fs}, @samp{gs}
43268@item
43269@samp{st0} through @samp{st7}
43270@item
43271@samp{fctrl}, @samp{fstat}, @samp{ftag}, @samp{fiseg}, @samp{fioff},
43272@samp{foseg}, @samp{fooff} and @samp{fop}
43273@end itemize
43274
43275The register sets may be different, depending on the target.
43276
3a13a53b 43277The @samp{org.gnu.gdb.i386.sse} feature is optional. It should
3bb8d5c3
L
43278describe registers:
43279
43280@itemize @minus
43281@item
43282@samp{xmm0} through @samp{xmm7} for i386
43283@item
43284@samp{xmm0} through @samp{xmm15} for amd64
43285@item
43286@samp{mxcsr}
43287@end itemize
43288
3a13a53b
L
43289The @samp{org.gnu.gdb.i386.avx} feature is optional and requires the
43290@samp{org.gnu.gdb.i386.sse} feature. It should
f68eb612
L
43291describe the upper 128 bits of @sc{ymm} registers:
43292
43293@itemize @minus
43294@item
43295@samp{ymm0h} through @samp{ymm7h} for i386
43296@item
43297@samp{ymm0h} through @samp{ymm15h} for amd64
f68eb612
L
43298@end itemize
43299
bc504a31 43300The @samp{org.gnu.gdb.i386.mpx} is an optional feature representing Intel
ca8941bb
WT
43301Memory Protection Extension (MPX). It should describe the following registers:
43302
43303@itemize @minus
43304@item
43305@samp{bnd0raw} through @samp{bnd3raw} for i386 and amd64.
43306@item
43307@samp{bndcfgu} and @samp{bndstatus} for i386 and amd64.
43308@end itemize
43309
3bb8d5c3
L
43310The @samp{org.gnu.gdb.i386.linux} feature is optional. It should
43311describe a single register, @samp{orig_eax}.
43312
2735833d
WT
43313The @samp{org.gnu.gdb.i386.segments} feature is optional. It should
43314describe two system registers: @samp{fs_base} and @samp{gs_base}.
43315
01f9f808
MS
43316The @samp{org.gnu.gdb.i386.avx512} feature is optional and requires the
43317@samp{org.gnu.gdb.i386.avx} feature. It should
43318describe additional @sc{xmm} registers:
43319
43320@itemize @minus
43321@item
43322@samp{xmm16h} through @samp{xmm31h}, only valid for amd64.
43323@end itemize
43324
43325It should describe the upper 128 bits of additional @sc{ymm} registers:
43326
43327@itemize @minus
43328@item
43329@samp{ymm16h} through @samp{ymm31h}, only valid for amd64.
43330@end itemize
43331
43332It should
43333describe the upper 256 bits of @sc{zmm} registers:
43334
43335@itemize @minus
43336@item
43337@samp{zmm0h} through @samp{zmm7h} for i386.
43338@item
43339@samp{zmm0h} through @samp{zmm15h} for amd64.
43340@end itemize
43341
43342It should
43343describe the additional @sc{zmm} registers:
43344
43345@itemize @minus
43346@item
43347@samp{zmm16h} through @samp{zmm31h}, only valid for amd64.
43348@end itemize
43349
51547df6
MS
43350The @samp{org.gnu.gdb.i386.pkeys} feature is optional. It should
43351describe a single register, @samp{pkru}. It is a 32-bit register
43352valid for i386 and amd64.
43353
164224e9
ME
43354@node MicroBlaze Features
43355@subsection MicroBlaze Features
43356@cindex target descriptions, MicroBlaze features
43357
43358The @samp{org.gnu.gdb.microblaze.core} feature is required for MicroBlaze
43359targets. It should contain registers @samp{r0} through @samp{r31},
43360@samp{rpc}, @samp{rmsr}, @samp{rear}, @samp{resr}, @samp{rfsr}, @samp{rbtr},
43361@samp{rpvr}, @samp{rpvr1} through @samp{rpvr11}, @samp{redr}, @samp{rpid},
43362@samp{rzpr}, @samp{rtlbx}, @samp{rtlbsx}, @samp{rtlblo}, and @samp{rtlbhi}.
43363
43364The @samp{org.gnu.gdb.microblaze.stack-protect} feature is optional.
43365If present, it should contain registers @samp{rshr} and @samp{rslr}
43366
1e26b4f8 43367@node MIPS Features
eb17f351
EZ
43368@subsection @acronym{MIPS} Features
43369@cindex target descriptions, @acronym{MIPS} features
f8b73d13 43370
eb17f351 43371The @samp{org.gnu.gdb.mips.cpu} feature is required for @acronym{MIPS} targets.
f8b73d13
DJ
43372It should contain registers @samp{r0} through @samp{r31}, @samp{lo},
43373@samp{hi}, and @samp{pc}. They may be 32-bit or 64-bit depending
43374on the target.
43375
43376The @samp{org.gnu.gdb.mips.cp0} feature is also required. It should
43377contain at least the @samp{status}, @samp{badvaddr}, and @samp{cause}
43378registers. They may be 32-bit or 64-bit depending on the target.
43379
43380The @samp{org.gnu.gdb.mips.fpu} feature is currently required, though
43381it may be optional in a future version of @value{GDBN}. It should
43382contain registers @samp{f0} through @samp{f31}, @samp{fcsr}, and
43383@samp{fir}. They may be 32-bit or 64-bit depending on the target.
43384
1faeff08
MR
43385The @samp{org.gnu.gdb.mips.dsp} feature is optional. It should
43386contain registers @samp{hi1} through @samp{hi3}, @samp{lo1} through
43387@samp{lo3}, and @samp{dspctl}. The @samp{dspctl} register should
43388be 32-bit and the rest may be 32-bit or 64-bit depending on the target.
43389
822b6570
DJ
43390The @samp{org.gnu.gdb.mips.linux} feature is optional. It should
43391contain a single register, @samp{restart}, which is used by the
43392Linux kernel to control restartable syscalls.
43393
e9c17194
VP
43394@node M68K Features
43395@subsection M68K Features
43396@cindex target descriptions, M68K features
43397
43398@table @code
43399@item @samp{org.gnu.gdb.m68k.core}
43400@itemx @samp{org.gnu.gdb.coldfire.core}
43401@itemx @samp{org.gnu.gdb.fido.core}
43402One of those features must be always present.
249e1128 43403The feature that is present determines which flavor of m68k is
e9c17194
VP
43404used. The feature that is present should contain registers
43405@samp{d0} through @samp{d7}, @samp{a0} through @samp{a5}, @samp{fp},
43406@samp{sp}, @samp{ps} and @samp{pc}.
43407
43408@item @samp{org.gnu.gdb.coldfire.fp}
43409This feature is optional. If present, it should contain registers
43410@samp{fp0} through @samp{fp7}, @samp{fpcontrol}, @samp{fpstatus} and
43411@samp{fpiaddr}.
43412@end table
43413
a28d8e50
YTL
43414@node NDS32 Features
43415@subsection NDS32 Features
43416@cindex target descriptions, NDS32 features
43417
43418The @samp{org.gnu.gdb.nds32.core} feature is required for NDS32
43419targets. It should contain at least registers @samp{r0} through
43420@samp{r10}, @samp{r15}, @samp{fp}, @samp{gp}, @samp{lp}, @samp{sp},
43421and @samp{pc}.
43422
43423The @samp{org.gnu.gdb.nds32.fpu} feature is optional. If present,
43424it should contain 64-bit double-precision floating-point registers
43425@samp{fd0} through @emph{fdN}, which should be @samp{fd3}, @samp{fd7},
43426@samp{fd15}, or @samp{fd31} based on the FPU configuration implemented.
43427
43428@emph{Note:} The first sixteen 64-bit double-precision floating-point
43429registers are overlapped with the thirty-two 32-bit single-precision
43430floating-point registers. The 32-bit single-precision registers, if
43431not being listed explicitly, will be synthesized from halves of the
43432overlapping 64-bit double-precision registers. Listing 32-bit
43433single-precision registers explicitly is deprecated, and the
43434support to it could be totally removed some day.
43435
a1217d97
SL
43436@node Nios II Features
43437@subsection Nios II Features
43438@cindex target descriptions, Nios II features
43439
43440The @samp{org.gnu.gdb.nios2.cpu} feature is required for Nios II
43441targets. It should contain the 32 core registers (@samp{zero},
43442@samp{at}, @samp{r2} through @samp{r23}, @samp{et} through @samp{ra}),
43443@samp{pc}, and the 16 control registers (@samp{status} through
43444@samp{mpuacc}).
43445
a994fec4
FJ
43446@node OpenRISC 1000 Features
43447@subsection Openrisc 1000 Features
43448@cindex target descriptions, OpenRISC 1000 features
43449
43450The @samp{org.gnu.gdb.or1k.group0} feature is required for OpenRISC 1000
43451targets. It should contain the 32 general purpose registers (@samp{r0}
43452through @samp{r31}), @samp{ppc}, @samp{npc} and @samp{sr}.
43453
1e26b4f8 43454@node PowerPC Features
7cc46491
DJ
43455@subsection PowerPC Features
43456@cindex target descriptions, PowerPC features
43457
43458The @samp{org.gnu.gdb.power.core} feature is required for PowerPC
43459targets. It should contain registers @samp{r0} through @samp{r31},
43460@samp{pc}, @samp{msr}, @samp{cr}, @samp{lr}, @samp{ctr}, and
43461@samp{xer}. They may be 32-bit or 64-bit depending on the target.
43462
43463The @samp{org.gnu.gdb.power.fpu} feature is optional. It should
43464contain registers @samp{f0} through @samp{f31} and @samp{fpscr}.
43465
43466The @samp{org.gnu.gdb.power.altivec} feature is optional. It should
6f072a10
PFC
43467contain registers @samp{vr0} through @samp{vr31}, @samp{vscr}, and
43468@samp{vrsave}. @value{GDBN} will define pseudo-registers @samp{v0}
43469through @samp{v31} as aliases for the corresponding @samp{vrX}
43470registers.
7cc46491 43471
677c5bb1 43472The @samp{org.gnu.gdb.power.vsx} feature is optional. It should
4b905ae1
PFC
43473contain registers @samp{vs0h} through @samp{vs31h}. @value{GDBN} will
43474combine these registers with the floating point registers (@samp{f0}
43475through @samp{f31}) and the altivec registers (@samp{vr0} through
43476@samp{vr31}) to present the 128-bit wide registers @samp{vs0} through
43477@samp{vs63}, the set of vector-scalar registers for POWER7.
43478Therefore, this feature requires both @samp{org.gnu.gdb.power.fpu} and
43479@samp{org.gnu.gdb.power.altivec}.
677c5bb1 43480
7cc46491
DJ
43481The @samp{org.gnu.gdb.power.spe} feature is optional. It should
43482contain registers @samp{ev0h} through @samp{ev31h}, @samp{acc}, and
43483@samp{spefscr}. SPE targets should provide 32-bit registers in
43484@samp{org.gnu.gdb.power.core} and provide the upper halves in
43485@samp{ev0h} through @samp{ev31h}. @value{GDBN} will combine
43486these to present registers @samp{ev0} through @samp{ev31} to the
43487user.
43488
7ca18ed6
EBM
43489The @samp{org.gnu.gdb.power.ppr} feature is optional. It should
43490contain the 64-bit register @samp{ppr}.
43491
43492The @samp{org.gnu.gdb.power.dscr} feature is optional. It should
43493contain the 64-bit register @samp{dscr}.
43494
f2cf6173
EBM
43495The @samp{org.gnu.gdb.power.tar} feature is optional. It should
43496contain the 64-bit register @samp{tar}.
43497
232bfb86
EBM
43498The @samp{org.gnu.gdb.power.ebb} feature is optional. It should
43499contain registers @samp{bescr}, @samp{ebbhr} and @samp{ebbrr}, all
4350064-bit wide.
43501
43502The @samp{org.gnu.gdb.power.linux.pmu} feature is optional. It should
43503contain registers @samp{mmcr0}, @samp{mmcr2}, @samp{siar}, @samp{sdar}
43504and @samp{sier}, all 64-bit wide. This is the subset of the isa 2.07
43505server PMU registers provided by @sc{gnu}/Linux.
43506
8d619c01
EBM
43507The @samp{org.gnu.gdb.power.htm.spr} feature is optional. It should
43508contain registers @samp{tfhar}, @samp{texasr} and @samp{tfiar}, all
4350964-bit wide.
43510
43511The @samp{org.gnu.gdb.power.htm.core} feature is optional. It should
43512contain the checkpointed general-purpose registers @samp{cr0} through
43513@samp{cr31}, as well as the checkpointed registers @samp{clr} and
43514@samp{cctr}. These registers may all be either 32-bit or 64-bit
43515depending on the target. It should also contain the checkpointed
43516registers @samp{ccr} and @samp{cxer}, which should both be 32-bit
43517wide.
43518
43519The @samp{org.gnu.gdb.power.htm.fpu} feature is optional. It should
43520contain the checkpointed 64-bit floating-point registers @samp{cf0}
43521through @samp{cf31}, as well as the checkpointed 64-bit register
43522@samp{cfpscr}.
43523
43524The @samp{org.gnu.gdb.power.htm.altivec} feature is optional. It
43525should contain the checkpointed altivec registers @samp{cvr0} through
43526@samp{cvr31}, all 128-bit wide. It should also contain the
43527checkpointed registers @samp{cvscr} and @samp{cvrsave}, both 32-bit
43528wide.
43529
43530The @samp{org.gnu.gdb.power.htm.vsx} feature is optional. It should
43531contain registers @samp{cvs0h} through @samp{cvs31h}. @value{GDBN}
43532will combine these registers with the checkpointed floating point
43533registers (@samp{cf0} through @samp{cf31}) and the checkpointed
43534altivec registers (@samp{cvr0} through @samp{cvr31}) to present the
43535128-bit wide checkpointed vector-scalar registers @samp{cvs0} through
43536@samp{cvs63}. Therefore, this feature requires both
43537@samp{org.gnu.gdb.power.htm.altivec} and
43538@samp{org.gnu.gdb.power.htm.fpu}.
43539
43540The @samp{org.gnu.gdb.power.htm.ppr} feature is optional. It should
43541contain the 64-bit checkpointed register @samp{cppr}.
43542
43543The @samp{org.gnu.gdb.power.htm.dscr} feature is optional. It should
43544contain the 64-bit checkpointed register @samp{cdscr}.
43545
43546The @samp{org.gnu.gdb.power.htm.tar} feature is optional. It should
43547contain the 64-bit checkpointed register @samp{ctar}.
43548
b5ffee31
AB
43549
43550@node RISC-V Features
43551@subsection RISC-V Features
43552@cindex target descriptions, RISC-V Features
43553
43554The @samp{org.gnu.gdb.riscv.cpu} feature is required for RISC-V
43555targets. It should contain the registers @samp{x0} through
43556@samp{x31}, and @samp{pc}. Either the architectural names (@samp{x0},
43557@samp{x1}, etc) can be used, or the ABI names (@samp{zero}, @samp{ra},
43558etc).
43559
43560The @samp{org.gnu.gdb.riscv.fpu} feature is optional. If present, it
43561should contain registers @samp{f0} through @samp{f31}, @samp{fflags},
43562@samp{frm}, and @samp{fcsr}. As with the cpu feature, either the
43563architectural register names, or the ABI names can be used.
43564
43565The @samp{org.gnu.gdb.riscv.virtual} feature is optional. If present,
43566it should contain registers that are not backed by real registers on
43567the target, but are instead virtual, where the register value is
43568derived from other target state. In many ways these are like
43569@value{GDBN}s pseudo-registers, except implemented by the target.
43570Currently the only register expected in this set is the one byte
43571@samp{priv} register that contains the target's privilege level in the
43572least significant two bits.
43573
43574The @samp{org.gnu.gdb.riscv.csr} feature is optional. If present, it
43575should contain all of the target's standard CSRs. Standard CSRs are
43576those defined in the RISC-V specification documents. There is some
43577overlap between this feature and the fpu feature; the @samp{fflags},
43578@samp{frm}, and @samp{fcsr} registers could be in either feature. The
43579expectation is that these registers will be in the fpu feature if the
43580target has floating point hardware, but can be moved into the csr
43581feature if the target has the floating point control registers, but no
43582other floating point hardware.
43583
4ac33720
UW
43584@node S/390 and System z Features
43585@subsection S/390 and System z Features
43586@cindex target descriptions, S/390 features
43587@cindex target descriptions, System z features
43588
43589The @samp{org.gnu.gdb.s390.core} feature is required for S/390 and
43590System z targets. It should contain the PSW and the 16 general
43591registers. In particular, System z targets should provide the 64-bit
43592registers @samp{pswm}, @samp{pswa}, and @samp{r0} through @samp{r15}.
43593S/390 targets should provide the 32-bit versions of these registers.
43594A System z target that runs in 31-bit addressing mode should provide
4359532-bit versions of @samp{pswm} and @samp{pswa}, as well as the general
43596register's upper halves @samp{r0h} through @samp{r15h}, and their
43597lower halves @samp{r0l} through @samp{r15l}.
43598
43599The @samp{org.gnu.gdb.s390.fpr} feature is required. It should
43600contain the 64-bit registers @samp{f0} through @samp{f15}, and
43601@samp{fpc}.
43602
43603The @samp{org.gnu.gdb.s390.acr} feature is required. It should
43604contain the 32-bit registers @samp{acr0} through @samp{acr15}.
43605
43606The @samp{org.gnu.gdb.s390.linux} feature is optional. It should
43607contain the register @samp{orig_r2}, which is 64-bit wide on System z
43608targets and 32-bit otherwise. In addition, the feature may contain
43609the @samp{last_break} register, whose width depends on the addressing
43610mode, as well as the @samp{system_call} register, which is always
4361132-bit wide.
43612
43613The @samp{org.gnu.gdb.s390.tdb} feature is optional. It should
43614contain the 64-bit registers @samp{tdb0}, @samp{tac}, @samp{tct},
43615@samp{atia}, and @samp{tr0} through @samp{tr15}.
43616
446899e4
AA
43617The @samp{org.gnu.gdb.s390.vx} feature is optional. It should contain
4361864-bit wide registers @samp{v0l} through @samp{v15l}, which will be
43619combined by @value{GDBN} with the floating point registers @samp{f0}
43620through @samp{f15} to present the 128-bit wide vector registers
43621@samp{v0} through @samp{v15}. In addition, this feature should
43622contain the 128-bit wide vector registers @samp{v16} through
43623@samp{v31}.
43624
289e23aa
AA
43625The @samp{org.gnu.gdb.s390.gs} feature is optional. It should contain
43626the 64-bit wide guarded-storage-control registers @samp{gsd},
43627@samp{gssm}, and @samp{gsepla}.
43628
43629The @samp{org.gnu.gdb.s390.gsbc} feature is optional. It should contain
43630the 64-bit wide guarded-storage broadcast control registers
43631@samp{bc_gsd}, @samp{bc_gssm}, and @samp{bc_gsepla}.
43632
3f7b46f2
IR
43633@node Sparc Features
43634@subsection Sparc Features
43635@cindex target descriptions, sparc32 features
43636@cindex target descriptions, sparc64 features
43637The @samp{org.gnu.gdb.sparc.cpu} feature is required for sparc32/sparc64
43638targets. It should describe the following registers:
43639
43640@itemize @minus
43641@item
43642@samp{g0} through @samp{g7}
43643@item
43644@samp{o0} through @samp{o7}
43645@item
43646@samp{l0} through @samp{l7}
43647@item
43648@samp{i0} through @samp{i7}
43649@end itemize
43650
43651They may be 32-bit or 64-bit depending on the target.
43652
43653Also the @samp{org.gnu.gdb.sparc.fpu} feature is required for sparc32/sparc64
43654targets. It should describe the following registers:
43655
43656@itemize @minus
43657@item
43658@samp{f0} through @samp{f31}
43659@item
43660@samp{f32} through @samp{f62} for sparc64
43661@end itemize
43662
43663The @samp{org.gnu.gdb.sparc.cp0} feature is required for sparc32/sparc64
43664targets. It should describe the following registers:
43665
43666@itemize @minus
43667@item
43668@samp{y}, @samp{psr}, @samp{wim}, @samp{tbr}, @samp{pc}, @samp{npc},
43669@samp{fsr}, and @samp{csr} for sparc32
43670@item
43671@samp{pc}, @samp{npc}, @samp{state}, @samp{fsr}, @samp{fprs}, and @samp{y}
43672for sparc64
43673@end itemize
43674
224bbe49
YQ
43675@node TIC6x Features
43676@subsection TMS320C6x Features
43677@cindex target descriptions, TIC6x features
43678@cindex target descriptions, TMS320C6x features
43679The @samp{org.gnu.gdb.tic6x.core} feature is required for TMS320C6x
43680targets. It should contain registers @samp{A0} through @samp{A15},
43681registers @samp{B0} through @samp{B15}, @samp{CSR} and @samp{PC}.
43682
43683The @samp{org.gnu.gdb.tic6x.gp} feature is optional. It should
43684contain registers @samp{A16} through @samp{A31} and @samp{B16}
43685through @samp{B31}.
43686
43687The @samp{org.gnu.gdb.tic6x.c6xp} feature is optional. It should
43688contain registers @samp{TSR}, @samp{ILC} and @samp{RILC}.
43689
07e059b5
VP
43690@node Operating System Information
43691@appendix Operating System Information
43692@cindex operating system information
43693
43694@menu
43695* Process list::
43696@end menu
43697
43698Users of @value{GDBN} often wish to obtain information about the state of
43699the operating system running on the target---for example the list of
43700processes, or the list of open files. This section describes the
43701mechanism that makes it possible. This mechanism is similar to the
43702target features mechanism (@pxref{Target Descriptions}), but focuses
43703on a different aspect of target.
43704
43705Operating system information is retrived from the target via the
43706remote protocol, using @samp{qXfer} requests (@pxref{qXfer osdata
43707read}). The object name in the request should be @samp{osdata}, and
43708the @var{annex} identifies the data to be fetched.
43709
43710@node Process list
43711@appendixsection Process list
43712@cindex operating system information, process list
43713
43714When requesting the process list, the @var{annex} field in the
43715@samp{qXfer} request should be @samp{processes}. The returned data is
43716an XML document. The formal syntax of this document is defined in
43717@file{gdb/features/osdata.dtd}.
43718
43719An example document is:
43720
43721@smallexample
43722<?xml version="1.0"?>
43723<!DOCTYPE target SYSTEM "osdata.dtd">
43724<osdata type="processes">
43725 <item>
43726 <column name="pid">1</column>
43727 <column name="user">root</column>
43728 <column name="command">/sbin/init</column>
dc146f7c 43729 <column name="cores">1,2,3</column>
07e059b5
VP
43730 </item>
43731</osdata>
43732@end smallexample
43733
43734Each item should include a column whose name is @samp{pid}. The value
43735of that column should identify the process on the target. The
43736@samp{user} and @samp{command} columns are optional, and will be
dc146f7c
VP
43737displayed by @value{GDBN}. The @samp{cores} column, if present,
43738should contain a comma-separated list of cores that this process
43739is running on. Target may provide additional columns,
07e059b5
VP
43740which @value{GDBN} currently ignores.
43741
05c8c3f5
TT
43742@node Trace File Format
43743@appendix Trace File Format
43744@cindex trace file format
43745
43746The trace file comes in three parts: a header, a textual description
43747section, and a trace frame section with binary data.
43748
43749The header has the form @code{\x7fTRACE0\n}. The first byte is
43750@code{0x7f} so as to indicate that the file contains binary data,
43751while the @code{0} is a version number that may have different values
43752in the future.
43753
43754The description section consists of multiple lines of @sc{ascii} text
43755separated by newline characters (@code{0xa}). The lines may include a
43756variety of optional descriptive or context-setting information, such
43757as tracepoint definitions or register set size. @value{GDBN} will
43758ignore any line that it does not recognize. An empty line marks the end
43759of this section.
43760
0748bf3e
MK
43761@table @code
43762@item R @var{size}
43763Specifies the size of a register block in bytes. This is equal to the
43764size of a @code{g} packet payload in the remote protocol. @var{size}
43765is an ascii decimal number. There should be only one such line in
43766a single trace file.
43767
43768@item status @var{status}
43769Trace status. @var{status} has the same format as a @code{qTStatus}
43770remote packet reply. There should be only one such line in a single trace
43771file.
43772
43773@item tp @var{payload}
43774Tracepoint definition. The @var{payload} has the same format as
43775@code{qTfP}/@code{qTsP} remote packet reply payload. A single tracepoint
43776may take multiple lines of definition, corresponding to the multiple
43777reply packets.
43778
43779@item tsv @var{payload}
43780Trace state variable definition. The @var{payload} has the same format as
43781@code{qTfV}/@code{qTsV} remote packet reply payload. A single variable
43782may take multiple lines of definition, corresponding to the multiple
43783reply packets.
43784
43785@item tdesc @var{payload}
43786Target description in XML format. The @var{payload} is a single line of
43787the XML file. All such lines should be concatenated together to get
43788the original XML file. This file is in the same format as @code{qXfer}
43789@code{features} payload, and corresponds to the main @code{target.xml}
43790file. Includes are not allowed.
43791
43792@end table
05c8c3f5
TT
43793
43794The trace frame section consists of a number of consecutive frames.
43795Each frame begins with a two-byte tracepoint number, followed by a
43796four-byte size giving the amount of data in the frame. The data in
43797the frame consists of a number of blocks, each introduced by a
43798character indicating its type (at least register, memory, and trace
43799state variable). The data in this section is raw binary, not a
43800hexadecimal or other encoding; its endianness matches the target's
43801endianness.
43802
43803@c FIXME bi-arch may require endianness/arch info in description section
43804
43805@table @code
43806@item R @var{bytes}
43807Register block. The number and ordering of bytes matches that of a
43808@code{g} packet in the remote protocol. Note that these are the
e909d859 43809actual bytes, in target order, not a hexadecimal encoding.
05c8c3f5
TT
43810
43811@item M @var{address} @var{length} @var{bytes}...
43812Memory block. This is a contiguous block of memory, at the 8-byte
43813address @var{address}, with a 2-byte length @var{length}, followed by
43814@var{length} bytes.
43815
43816@item V @var{number} @var{value}
43817Trace state variable block. This records the 8-byte signed value
43818@var{value} of trace state variable numbered @var{number}.
43819
43820@end table
43821
43822Future enhancements of the trace file format may include additional types
43823of blocks.
43824
90476074
TT
43825@node Index Section Format
43826@appendix @code{.gdb_index} section format
43827@cindex .gdb_index section format
43828@cindex index section format
43829
43830This section documents the index section that is created by @code{save
43831gdb-index} (@pxref{Index Files}). The index section is
43832DWARF-specific; some knowledge of DWARF is assumed in this
43833description.
43834
43835The mapped index file format is designed to be directly
43836@code{mmap}able on any architecture. In most cases, a datum is
43837represented using a little-endian 32-bit integer value, called an
43838@code{offset_type}. Big endian machines must byte-swap the values
43839before using them. Exceptions to this rule are noted. The data is
43840laid out such that alignment is always respected.
43841
43842A mapped index consists of several areas, laid out in order.
43843
43844@enumerate
43845@item
43846The file header. This is a sequence of values, of @code{offset_type}
43847unless otherwise noted:
43848
43849@enumerate
43850@item
796a7ff8 43851The version number, currently 8. Versions 1, 2 and 3 are obsolete.
481860b3 43852Version 4 uses a different hashing function from versions 5 and 6.
b6ba681c
TT
43853Version 6 includes symbols for inlined functions, whereas versions 4
43854and 5 do not. Version 7 adds attributes to the CU indices in the
796a7ff8
DE
43855symbol table. Version 8 specifies that symbols from DWARF type units
43856(@samp{DW_TAG_type_unit}) refer to the type unit's symbol table and not the
43857compilation unit (@samp{DW_TAG_comp_unit}) using the type.
43858
43859@value{GDBN} will only read version 4, 5, or 6 indices
e615022a 43860by specifying @code{set use-deprecated-index-sections on}.
796a7ff8
DE
43861GDB has a workaround for potentially broken version 7 indices so it is
43862currently not flagged as deprecated.
90476074
TT
43863
43864@item
43865The offset, from the start of the file, of the CU list.
43866
43867@item
43868The offset, from the start of the file, of the types CU list. Note
43869that this area can be empty, in which case this offset will be equal
43870to the next offset.
43871
43872@item
43873The offset, from the start of the file, of the address area.
43874
43875@item
43876The offset, from the start of the file, of the symbol table.
43877
43878@item
43879The offset, from the start of the file, of the constant pool.
43880@end enumerate
43881
43882@item
43883The CU list. This is a sequence of pairs of 64-bit little-endian
43884values, sorted by the CU offset. The first element in each pair is
43885the offset of a CU in the @code{.debug_info} section. The second
43886element in each pair is the length of that CU. References to a CU
43887elsewhere in the map are done using a CU index, which is just the
438880-based index into this table. Note that if there are type CUs, then
43889conceptually CUs and type CUs form a single list for the purposes of
43890CU indices.
43891
43892@item
43893The types CU list. This is a sequence of triplets of 64-bit
43894little-endian values. In a triplet, the first value is the CU offset,
43895the second value is the type offset in the CU, and the third value is
43896the type signature. The types CU list is not sorted.
43897
43898@item
43899The address area. The address area consists of a sequence of address
43900entries. Each address entry has three elements:
43901
43902@enumerate
43903@item
43904The low address. This is a 64-bit little-endian value.
43905
43906@item
43907The high address. This is a 64-bit little-endian value. Like
43908@code{DW_AT_high_pc}, the value is one byte beyond the end.
43909
43910@item
43911The CU index. This is an @code{offset_type} value.
43912@end enumerate
43913
43914@item
43915The symbol table. This is an open-addressed hash table. The size of
43916the hash table is always a power of 2.
43917
43918Each slot in the hash table consists of a pair of @code{offset_type}
43919values. The first value is the offset of the symbol's name in the
43920constant pool. The second value is the offset of the CU vector in the
43921constant pool.
43922
43923If both values are 0, then this slot in the hash table is empty. This
43924is ok because while 0 is a valid constant pool index, it cannot be a
43925valid index for both a string and a CU vector.
43926
43927The hash value for a table entry is computed by applying an
43928iterative hash function to the symbol's name. Starting with an
43929initial value of @code{r = 0}, each (unsigned) character @samp{c} in
559a7a62
JK
43930the string is incorporated into the hash using the formula depending on the
43931index version:
43932
43933@table @asis
43934@item Version 4
43935The formula is @code{r = r * 67 + c - 113}.
43936
156942c7 43937@item Versions 5 to 7
559a7a62
JK
43938The formula is @code{r = r * 67 + tolower (c) - 113}.
43939@end table
43940
43941The terminating @samp{\0} is not incorporated into the hash.
90476074
TT
43942
43943The step size used in the hash table is computed via
43944@code{((hash * 17) & (size - 1)) | 1}, where @samp{hash} is the hash
43945value, and @samp{size} is the size of the hash table. The step size
43946is used to find the next candidate slot when handling a hash
43947collision.
43948
43949The names of C@t{++} symbols in the hash table are canonicalized. We
43950don't currently have a simple description of the canonicalization
43951algorithm; if you intend to create new index sections, you must read
43952the code.
43953
43954@item
43955The constant pool. This is simply a bunch of bytes. It is organized
43956so that alignment is correct: CU vectors are stored first, followed by
43957strings.
43958
43959A CU vector in the constant pool is a sequence of @code{offset_type}
43960values. The first value is the number of CU indices in the vector.
156942c7
DE
43961Each subsequent value is the index and symbol attributes of a CU in
43962the CU list. This element in the hash table is used to indicate which
43963CUs define the symbol and how the symbol is used.
43964See below for the format of each CU index+attributes entry.
90476074
TT
43965
43966A string in the constant pool is zero-terminated.
43967@end enumerate
43968
156942c7
DE
43969Attributes were added to CU index values in @code{.gdb_index} version 7.
43970If a symbol has multiple uses within a CU then there is one
43971CU index+attributes value for each use.
43972
43973The format of each CU index+attributes entry is as follows
43974(bit 0 = LSB):
43975
43976@table @asis
43977
43978@item Bits 0-23
43979This is the index of the CU in the CU list.
43980@item Bits 24-27
43981These bits are reserved for future purposes and must be zero.
43982@item Bits 28-30
43983The kind of the symbol in the CU.
43984
43985@table @asis
43986@item 0
43987This value is reserved and should not be used.
43988By reserving zero the full @code{offset_type} value is backwards compatible
43989with previous versions of the index.
43990@item 1
43991The symbol is a type.
43992@item 2
43993The symbol is a variable or an enum value.
43994@item 3
43995The symbol is a function.
43996@item 4
43997Any other kind of symbol.
43998@item 5,6,7
43999These values are reserved.
44000@end table
44001
44002@item Bit 31
44003This bit is zero if the value is global and one if it is static.
44004
44005The determination of whether a symbol is global or static is complicated.
44006The authorative reference is the file @file{dwarf2read.c} in
44007@value{GDBN} sources.
44008
44009@end table
44010
44011This pseudo-code describes the computation of a symbol's kind and
44012global/static attributes in the index.
44013
44014@smallexample
44015is_external = get_attribute (die, DW_AT_external);
44016language = get_attribute (cu_die, DW_AT_language);
44017switch (die->tag)
44018 @{
44019 case DW_TAG_typedef:
44020 case DW_TAG_base_type:
44021 case DW_TAG_subrange_type:
44022 kind = TYPE;
44023 is_static = 1;
44024 break;
44025 case DW_TAG_enumerator:
44026 kind = VARIABLE;
9c37b5ae 44027 is_static = language != CPLUS;
156942c7
DE
44028 break;
44029 case DW_TAG_subprogram:
44030 kind = FUNCTION;
44031 is_static = ! (is_external || language == ADA);
44032 break;
44033 case DW_TAG_constant:
44034 kind = VARIABLE;
44035 is_static = ! is_external;
44036 break;
44037 case DW_TAG_variable:
44038 kind = VARIABLE;
44039 is_static = ! is_external;
44040 break;
44041 case DW_TAG_namespace:
44042 kind = TYPE;
44043 is_static = 0;
44044 break;
44045 case DW_TAG_class_type:
44046 case DW_TAG_interface_type:
44047 case DW_TAG_structure_type:
44048 case DW_TAG_union_type:
44049 case DW_TAG_enumeration_type:
44050 kind = TYPE;
9c37b5ae 44051 is_static = language != CPLUS;
156942c7
DE
44052 break;
44053 default:
44054 assert (0);
44055 @}
44056@end smallexample
44057
43662968
JK
44058@node Man Pages
44059@appendix Manual pages
44060@cindex Man pages
44061
44062@menu
44063* gdb man:: The GNU Debugger man page
44064* gdbserver man:: Remote Server for the GNU Debugger man page
b292c783 44065* gcore man:: Generate a core file of a running program
43662968 44066* gdbinit man:: gdbinit scripts
ba643918 44067* gdb-add-index man:: Add index files to speed up GDB
43662968
JK
44068@end menu
44069
44070@node gdb man
44071@heading gdb man
44072
44073@c man title gdb The GNU Debugger
44074
44075@c man begin SYNOPSIS gdb
44076gdb [@option{-help}] [@option{-nh}] [@option{-nx}] [@option{-q}]
44077[@option{-batch}] [@option{-cd=}@var{dir}] [@option{-f}]
44078[@option{-b}@w{ }@var{bps}]
44079 [@option{-tty=}@var{dev}] [@option{-s} @var{symfile}]
44080[@option{-e}@w{ }@var{prog}] [@option{-se}@w{ }@var{prog}]
906ccdf0
JK
44081[@option{-c}@w{ }@var{core}] [@option{-p}@w{ }@var{procID}]
44082 [@option{-x}@w{ }@var{cmds}] [@option{-d}@w{ }@var{dir}]
44083[@var{prog}|@var{prog} @var{procID}|@var{prog} @var{core}]
43662968
JK
44084@c man end
44085
44086@c man begin DESCRIPTION gdb
44087The purpose of a debugger such as @value{GDBN} is to allow you to see what is
44088going on ``inside'' another program while it executes -- or what another
44089program was doing at the moment it crashed.
44090
44091@value{GDBN} can do four main kinds of things (plus other things in support of
44092these) to help you catch bugs in the act:
44093
44094@itemize @bullet
44095@item
44096Start your program, specifying anything that might affect its behavior.
44097
44098@item
44099Make your program stop on specified conditions.
44100
44101@item
44102Examine what has happened, when your program has stopped.
44103
44104@item
44105Change things in your program, so you can experiment with correcting the
44106effects of one bug and go on to learn about another.
44107@end itemize
44108
906ccdf0
JK
44109You can use @value{GDBN} to debug programs written in C, C@t{++}, Fortran and
44110Modula-2.
43662968
JK
44111
44112@value{GDBN} is invoked with the shell command @code{gdb}. Once started, it reads
44113commands from the terminal until you tell it to exit with the @value{GDBN}
44114command @code{quit}. You can get online help from @value{GDBN} itself
44115by using the command @code{help}.
44116
44117You can run @code{gdb} with no arguments or options; but the most
44118usual way to start @value{GDBN} is with one argument or two, specifying an
44119executable program as the argument:
44120
44121@smallexample
44122gdb program
44123@end smallexample
44124
44125You can also start with both an executable program and a core file specified:
44126
44127@smallexample
44128gdb program core
44129@end smallexample
44130
44131You can, instead, specify a process ID as a second argument, if you want
44132to debug a running process:
44133
44134@smallexample
44135gdb program 1234
906ccdf0 44136gdb -p 1234
43662968
JK
44137@end smallexample
44138
44139@noindent
44140would attach @value{GDBN} to process @code{1234} (unless you also have a file
44141named @file{1234}; @value{GDBN} does check for a core file first).
906ccdf0 44142With option @option{-p} you can omit the @var{program} filename.
43662968
JK
44143
44144Here are some of the most frequently needed @value{GDBN} commands:
44145
44146@c pod2man highlights the right hand side of the @item lines.
44147@table @env
224f10c1 44148@item break [@var{file}:]@var{function}
43662968
JK
44149Set a breakpoint at @var{function} (in @var{file}).
44150
44151@item run [@var{arglist}]
44152Start your program (with @var{arglist}, if specified).
44153
44154@item bt
44155Backtrace: display the program stack.
44156
44157@item print @var{expr}
44158Display the value of an expression.
44159
44160@item c
44161Continue running your program (after stopping, e.g. at a breakpoint).
44162
44163@item next
44164Execute next program line (after stopping); step @emph{over} any
44165function calls in the line.
44166
44167@item edit [@var{file}:]@var{function}
44168look at the program line where it is presently stopped.
44169
44170@item list [@var{file}:]@var{function}
44171type the text of the program in the vicinity of where it is presently stopped.
44172
44173@item step
44174Execute next program line (after stopping); step @emph{into} any
44175function calls in the line.
44176
44177@item help [@var{name}]
44178Show information about @value{GDBN} command @var{name}, or general information
44179about using @value{GDBN}.
44180
44181@item quit
44182Exit from @value{GDBN}.
44183@end table
44184
44185@ifset man
44186For full details on @value{GDBN},
44187see @cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44188by Richard M. Stallman and Roland H. Pesch. The same text is available online
44189as the @code{gdb} entry in the @code{info} program.
44190@end ifset
44191@c man end
44192
44193@c man begin OPTIONS gdb
44194Any arguments other than options specify an executable
44195file and core file (or process ID); that is, the first argument
44196encountered with no
44197associated option flag is equivalent to a @option{-se} option, and the second,
44198if any, is equivalent to a @option{-c} option if it's the name of a file.
44199Many options have
44200both long and short forms; both are shown here. The long forms are also
44201recognized if you truncate them, so long as enough of the option is
44202present to be unambiguous. (If you prefer, you can flag option
44203arguments with @option{+} rather than @option{-}, though we illustrate the
44204more usual convention.)
44205
44206All the options and command line arguments you give are processed
44207in sequential order. The order makes a difference when the @option{-x}
44208option is used.
44209
44210@table @env
44211@item -help
44212@itemx -h
44213List all options, with brief explanations.
44214
44215@item -symbols=@var{file}
44216@itemx -s @var{file}
44217Read symbol table from file @var{file}.
44218
44219@item -write
44220Enable writing into executable and core files.
44221
44222@item -exec=@var{file}
44223@itemx -e @var{file}
44224Use file @var{file} as the executable file to execute when
44225appropriate, and for examining pure data in conjunction with a core
44226dump.
44227
44228@item -se=@var{file}
44229Read symbol table from file @var{file} and use it as the executable
44230file.
44231
44232@item -core=@var{file}
44233@itemx -c @var{file}
44234Use file @var{file} as a core dump to examine.
44235
44236@item -command=@var{file}
44237@itemx -x @var{file}
44238Execute @value{GDBN} commands from file @var{file}.
44239
44240@item -ex @var{command}
44241Execute given @value{GDBN} @var{command}.
44242
44243@item -directory=@var{directory}
44244@itemx -d @var{directory}
44245Add @var{directory} to the path to search for source files.
44246
44247@item -nh
44248Do not execute commands from @file{~/.gdbinit}.
44249
44250@item -nx
44251@itemx -n
44252Do not execute commands from any @file{.gdbinit} initialization files.
44253
44254@item -quiet
44255@itemx -q
44256``Quiet''. Do not print the introductory and copyright messages. These
44257messages are also suppressed in batch mode.
44258
44259@item -batch
44260Run in batch mode. Exit with status @code{0} after processing all the command
44261files specified with @option{-x} (and @file{.gdbinit}, if not inhibited).
44262Exit with nonzero status if an error occurs in executing the @value{GDBN}
44263commands in the command files.
44264
44265Batch mode may be useful for running @value{GDBN} as a filter, for example to
44266download and run a program on another computer; in order to make this
44267more useful, the message
44268
44269@smallexample
44270Program exited normally.
44271@end smallexample
44272
44273@noindent
44274(which is ordinarily issued whenever a program running under @value{GDBN} control
44275terminates) is not issued when running in batch mode.
44276
44277@item -cd=@var{directory}
44278Run @value{GDBN} using @var{directory} as its working directory,
44279instead of the current directory.
44280
44281@item -fullname
44282@itemx -f
44283Emacs sets this option when it runs @value{GDBN} as a subprocess. It tells
44284@value{GDBN} to output the full file name and line number in a standard,
44285recognizable fashion each time a stack frame is displayed (which
44286includes each time the program stops). This recognizable format looks
44287like two @samp{\032} characters, followed by the file name, line number
44288and character position separated by colons, and a newline. The
44289Emacs-to-@value{GDBN} interface program uses the two @samp{\032}
44290characters as a signal to display the source code for the frame.
44291
44292@item -b @var{bps}
44293Set the line speed (baud rate or bits per second) of any serial
44294interface used by @value{GDBN} for remote debugging.
44295
44296@item -tty=@var{device}
44297Run using @var{device} for your program's standard input and output.
44298@end table
44299@c man end
44300
44301@c man begin SEEALSO gdb
44302@ifset man
44303The full documentation for @value{GDBN} is maintained as a Texinfo manual.
44304If the @code{info} and @code{gdb} programs and @value{GDBN}'s Texinfo
44305documentation are properly installed at your site, the command
44306
44307@smallexample
44308info gdb
44309@end smallexample
44310
44311@noindent
44312should give you access to the complete manual.
44313
44314@cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44315Richard M. Stallman and Roland H. Pesch, July 1991.
44316@end ifset
44317@c man end
44318
44319@node gdbserver man
44320@heading gdbserver man
44321
44322@c man title gdbserver Remote Server for the GNU Debugger
44323@format
44324@c man begin SYNOPSIS gdbserver
5b8b6385 44325gdbserver @var{comm} @var{prog} [@var{args}@dots{}]
43662968 44326
5b8b6385
JK
44327gdbserver --attach @var{comm} @var{pid}
44328
44329gdbserver --multi @var{comm}
43662968
JK
44330@c man end
44331@end format
44332
44333@c man begin DESCRIPTION gdbserver
44334@command{gdbserver} is a program that allows you to run @value{GDBN} on a different machine
44335than the one which is running the program being debugged.
44336
44337@ifclear man
44338@subheading Usage (server (target) side)
44339@end ifclear
44340@ifset man
44341Usage (server (target) side):
44342@end ifset
44343
44344First, you need to have a copy of the program you want to debug put onto
44345the target system. The program can be stripped to save space if needed, as
44346@command{gdbserver} doesn't care about symbols. All symbol handling is taken care of by
44347the @value{GDBN} running on the host system.
44348
44349To use the server, you log on to the target system, and run the @command{gdbserver}
44350program. You must tell it (a) how to communicate with @value{GDBN}, (b) the name of
44351your program, and (c) its arguments. The general syntax is:
44352
44353@smallexample
44354target> gdbserver @var{comm} @var{program} [@var{args} ...]
44355@end smallexample
44356
44357For example, using a serial port, you might say:
44358
44359@smallexample
44360@ifset man
44361@c @file would wrap it as F</dev/com1>.
44362target> gdbserver /dev/com1 emacs foo.txt
44363@end ifset
44364@ifclear man
44365target> gdbserver @file{/dev/com1} emacs foo.txt
44366@end ifclear
44367@end smallexample
44368
44369This tells @command{gdbserver} to debug emacs with an argument of foo.txt, and
44370to communicate with @value{GDBN} via @file{/dev/com1}. @command{gdbserver} now
44371waits patiently for the host @value{GDBN} to communicate with it.
44372
44373To use a TCP connection, you could say:
44374
44375@smallexample
44376target> gdbserver host:2345 emacs foo.txt
44377@end smallexample
44378
44379This says pretty much the same thing as the last example, except that we are
44380going to communicate with the @code{host} @value{GDBN} via TCP. The @code{host:2345} argument means
44381that we are expecting to see a TCP connection from @code{host} to local TCP port
443822345. (Currently, the @code{host} part is ignored.) You can choose any number you
44383want for the port number as long as it does not conflict with any existing TCP
44384ports on the target system. This same port number must be used in the host
44385@value{GDBN}s @code{target remote} command, which will be described shortly. Note that if
44386you chose a port number that conflicts with another service, @command{gdbserver} will
44387print an error message and exit.
44388
5b8b6385 44389@command{gdbserver} can also attach to running programs.
43662968
JK
44390This is accomplished via the @option{--attach} argument. The syntax is:
44391
44392@smallexample
5b8b6385 44393target> gdbserver --attach @var{comm} @var{pid}
43662968
JK
44394@end smallexample
44395
44396@var{pid} is the process ID of a currently running process. It isn't
44397necessary to point @command{gdbserver} at a binary for the running process.
44398
5b8b6385
JK
44399To start @code{gdbserver} without supplying an initial command to run
44400or process ID to attach, use the @option{--multi} command line option.
44401In such case you should connect using @kbd{target extended-remote} to start
44402the program you want to debug.
44403
44404@smallexample
44405target> gdbserver --multi @var{comm}
44406@end smallexample
44407
43662968
JK
44408@ifclear man
44409@subheading Usage (host side)
44410@end ifclear
44411@ifset man
44412Usage (host side):
44413@end ifset
44414
44415You need an unstripped copy of the target program on your host system, since
1a088a2e 44416@value{GDBN} needs to examine its symbol tables and such. Start up @value{GDBN} as you normally
43662968
JK
44417would, with the target program as the first argument. (You may need to use the
44418@option{--baud} option if the serial line is running at anything except 9600 baud.)
44419That is @code{gdb TARGET-PROG}, or @code{gdb --baud BAUD TARGET-PROG}. After that, the only
5b8b6385
JK
44420new command you need to know about is @code{target remote}
44421(or @code{target extended-remote}). Its argument is either
43662968
JK
44422a device name (usually a serial device, like @file{/dev/ttyb}), or a @code{HOST:PORT}
44423descriptor. For example:
44424
44425@smallexample
44426@ifset man
44427@c @file would wrap it as F</dev/ttyb>.
44428(gdb) target remote /dev/ttyb
44429@end ifset
44430@ifclear man
44431(gdb) target remote @file{/dev/ttyb}
44432@end ifclear
44433@end smallexample
44434
44435@noindent
44436communicates with the server via serial line @file{/dev/ttyb}, and:
44437
44438@smallexample
44439(gdb) target remote the-target:2345
44440@end smallexample
44441
44442@noindent
44443communicates via a TCP connection to port 2345 on host `the-target', where
44444you previously started up @command{gdbserver} with the same port number. Note that for
44445TCP connections, you must start up @command{gdbserver} prior to using the `target remote'
44446command, otherwise you may get an error that looks something like
44447`Connection refused'.
5b8b6385
JK
44448
44449@command{gdbserver} can also debug multiple inferiors at once,
44450described in
44451@ifset man
44452the @value{GDBN} manual in node @code{Inferiors and Programs}
44453-- shell command @code{info -f gdb -n 'Inferiors and Programs'}.
44454@end ifset
44455@ifclear man
44456@ref{Inferiors and Programs}.
44457@end ifclear
44458In such case use the @code{extended-remote} @value{GDBN} command variant:
44459
44460@smallexample
44461(gdb) target extended-remote the-target:2345
44462@end smallexample
44463
44464The @command{gdbserver} option @option{--multi} may or may not be used in such
44465case.
43662968
JK
44466@c man end
44467
44468@c man begin OPTIONS gdbserver
5b8b6385
JK
44469There are three different modes for invoking @command{gdbserver}:
44470
44471@itemize @bullet
44472
44473@item
44474Debug a specific program specified by its program name:
44475
44476@smallexample
44477gdbserver @var{comm} @var{prog} [@var{args}@dots{}]
44478@end smallexample
44479
44480The @var{comm} parameter specifies how should the server communicate
44481with @value{GDBN}; it is either a device name (to use a serial line),
44482a TCP port number (@code{:1234}), or @code{-} or @code{stdio} to use
44483stdin/stdout of @code{gdbserver}. Specify the name of the program to
44484debug in @var{prog}. Any remaining arguments will be passed to the
44485program verbatim. When the program exits, @value{GDBN} will close the
44486connection, and @code{gdbserver} will exit.
44487
44488@item
44489Debug a specific program by specifying the process ID of a running
44490program:
44491
44492@smallexample
44493gdbserver --attach @var{comm} @var{pid}
44494@end smallexample
44495
44496The @var{comm} parameter is as described above. Supply the process ID
44497of a running program in @var{pid}; @value{GDBN} will do everything
44498else. Like with the previous mode, when the process @var{pid} exits,
44499@value{GDBN} will close the connection, and @code{gdbserver} will exit.
44500
44501@item
44502Multi-process mode -- debug more than one program/process:
44503
44504@smallexample
44505gdbserver --multi @var{comm}
44506@end smallexample
44507
44508In this mode, @value{GDBN} can instruct @command{gdbserver} which
44509command(s) to run. Unlike the other 2 modes, @value{GDBN} will not
44510close the connection when a process being debugged exits, so you can
44511debug several processes in the same session.
44512@end itemize
44513
44514In each of the modes you may specify these options:
44515
44516@table @env
44517
44518@item --help
44519List all options, with brief explanations.
44520
44521@item --version
44522This option causes @command{gdbserver} to print its version number and exit.
44523
44524@item --attach
44525@command{gdbserver} will attach to a running program. The syntax is:
44526
44527@smallexample
44528target> gdbserver --attach @var{comm} @var{pid}
44529@end smallexample
44530
44531@var{pid} is the process ID of a currently running process. It isn't
44532necessary to point @command{gdbserver} at a binary for the running process.
44533
44534@item --multi
44535To start @code{gdbserver} without supplying an initial command to run
44536or process ID to attach, use this command line option.
44537Then you can connect using @kbd{target extended-remote} and start
44538the program you want to debug. The syntax is:
44539
44540@smallexample
44541target> gdbserver --multi @var{comm}
44542@end smallexample
44543
44544@item --debug
44545Instruct @code{gdbserver} to display extra status information about the debugging
44546process.
44547This option is intended for @code{gdbserver} development and for bug reports to
44548the developers.
44549
44550@item --remote-debug
44551Instruct @code{gdbserver} to display remote protocol debug output.
44552This option is intended for @code{gdbserver} development and for bug reports to
44553the developers.
44554
87ce2a04
DE
44555@item --debug-format=option1@r{[},option2,...@r{]}
44556Instruct @code{gdbserver} to include extra information in each line
44557of debugging output.
44558@xref{Other Command-Line Arguments for gdbserver}.
44559
5b8b6385
JK
44560@item --wrapper
44561Specify a wrapper to launch programs
44562for debugging. The option should be followed by the name of the
44563wrapper, then any command-line arguments to pass to the wrapper, then
44564@kbd{--} indicating the end of the wrapper arguments.
44565
44566@item --once
44567By default, @command{gdbserver} keeps the listening TCP port open, so that
44568additional connections are possible. However, if you start @code{gdbserver}
44569with the @option{--once} option, it will stop listening for any further
44570connection attempts after connecting to the first @value{GDBN} session.
44571
44572@c --disable-packet is not documented for users.
44573
44574@c --disable-randomization and --no-disable-randomization are superseded by
44575@c QDisableRandomization.
44576
44577@end table
43662968
JK
44578@c man end
44579
44580@c man begin SEEALSO gdbserver
44581@ifset man
44582The full documentation for @value{GDBN} is maintained as a Texinfo manual.
44583If the @code{info} and @code{gdb} programs and @value{GDBN}'s Texinfo
44584documentation are properly installed at your site, the command
44585
44586@smallexample
44587info gdb
44588@end smallexample
44589
44590should give you access to the complete manual.
44591
44592@cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44593Richard M. Stallman and Roland H. Pesch, July 1991.
44594@end ifset
44595@c man end
44596
b292c783
JK
44597@node gcore man
44598@heading gcore
44599
44600@c man title gcore Generate a core file of a running program
44601
44602@format
44603@c man begin SYNOPSIS gcore
129eb0f1 44604gcore [-a] [-o @var{prefix}] @var{pid1} [@var{pid2}...@var{pidN}]
b292c783
JK
44605@c man end
44606@end format
44607
44608@c man begin DESCRIPTION gcore
129eb0f1
SDJ
44609Generate core dumps of one or more running programs with process IDs
44610@var{pid1}, @var{pid2}, etc. A core file produced by @command{gcore}
44611is equivalent to one produced by the kernel when the process crashes
44612(and when @kbd{ulimit -c} was used to set up an appropriate core dump
44613limit). However, unlike after a crash, after @command{gcore} finishes
44614its job the program remains running without any change.
b292c783
JK
44615@c man end
44616
44617@c man begin OPTIONS gcore
44618@table @env
c179febe
SL
44619@item -a
44620Dump all memory mappings. The actual effect of this option depends on
44621the Operating System. On @sc{gnu}/Linux, it will disable
44622@code{use-coredump-filter} (@pxref{set use-coredump-filter}) and
44623enable @code{dump-excluded-mappings} (@pxref{set
44624dump-excluded-mappings}).
44625
129eb0f1
SDJ
44626@item -o @var{prefix}
44627The optional argument @var{prefix} specifies the prefix to be used
44628when composing the file names of the core dumps. The file name is
44629composed as @file{@var{prefix}.@var{pid}}, where @var{pid} is the
44630process ID of the running program being analyzed by @command{gcore}.
44631If not specified, @var{prefix} defaults to @var{gcore}.
b292c783
JK
44632@end table
44633@c man end
44634
44635@c man begin SEEALSO gcore
44636@ifset man
44637The full documentation for @value{GDBN} is maintained as a Texinfo manual.
44638If the @code{info} and @code{gdb} programs and @value{GDBN}'s Texinfo
44639documentation are properly installed at your site, the command
44640
44641@smallexample
44642info gdb
44643@end smallexample
44644
44645@noindent
44646should give you access to the complete manual.
44647
44648@cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44649Richard M. Stallman and Roland H. Pesch, July 1991.
44650@end ifset
44651@c man end
44652
43662968
JK
44653@node gdbinit man
44654@heading gdbinit
44655
44656@c man title gdbinit GDB initialization scripts
44657
44658@format
44659@c man begin SYNOPSIS gdbinit
44660@ifset SYSTEM_GDBINIT
44661@value{SYSTEM_GDBINIT}
44662@end ifset
44663
44664~/.gdbinit
44665
44666./.gdbinit
44667@c man end
44668@end format
44669
44670@c man begin DESCRIPTION gdbinit
44671These files contain @value{GDBN} commands to automatically execute during
44672@value{GDBN} startup. The lines of contents are canned sequences of commands,
44673described in
44674@ifset man
44675the @value{GDBN} manual in node @code{Sequences}
44676-- shell command @code{info -f gdb -n Sequences}.
44677@end ifset
44678@ifclear man
44679@ref{Sequences}.
44680@end ifclear
44681
44682Please read more in
44683@ifset man
44684the @value{GDBN} manual in node @code{Startup}
44685-- shell command @code{info -f gdb -n Startup}.
44686@end ifset
44687@ifclear man
44688@ref{Startup}.
44689@end ifclear
44690
44691@table @env
44692@ifset SYSTEM_GDBINIT
44693@item @value{SYSTEM_GDBINIT}
44694@end ifset
44695@ifclear SYSTEM_GDBINIT
44696@item (not enabled with @code{--with-system-gdbinit} during compilation)
44697@end ifclear
44698System-wide initialization file. It is executed unless user specified
44699@value{GDBN} option @code{-nx} or @code{-n}.
44700See more in
44701@ifset man
44702the @value{GDBN} manual in node @code{System-wide configuration}
44703-- shell command @code{info -f gdb -n 'System-wide configuration'}.
44704@end ifset
44705@ifclear man
44706@ref{System-wide configuration}.
44707@end ifclear
44708
44709@item ~/.gdbinit
44710User initialization file. It is executed unless user specified
44711@value{GDBN} options @code{-nx}, @code{-n} or @code{-nh}.
44712
44713@item ./.gdbinit
44714Initialization file for current directory. It may need to be enabled with
44715@value{GDBN} security command @code{set auto-load local-gdbinit}.
44716See more in
44717@ifset man
44718the @value{GDBN} manual in node @code{Init File in the Current Directory}
44719-- shell command @code{info -f gdb -n 'Init File in the Current Directory'}.
44720@end ifset
44721@ifclear man
44722@ref{Init File in the Current Directory}.
44723@end ifclear
44724@end table
44725@c man end
44726
44727@c man begin SEEALSO gdbinit
44728@ifset man
44729gdb(1), @code{info -f gdb -n Startup}
44730
44731The full documentation for @value{GDBN} is maintained as a Texinfo manual.
44732If the @code{info} and @code{gdb} programs and @value{GDBN}'s Texinfo
44733documentation are properly installed at your site, the command
ba643918
SDJ
44734
44735@smallexample
44736info gdb
44737@end smallexample
44738
44739should give you access to the complete manual.
44740
44741@cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44742Richard M. Stallman and Roland H. Pesch, July 1991.
44743@end ifset
44744@c man end
44745
44746@node gdb-add-index man
ba643918 44747@heading gdb-add-index
d726cb5d 44748@pindex gdb-add-index
dbfa4523 44749@anchor{gdb-add-index}
ba643918
SDJ
44750
44751@c man title gdb-add-index Add index files to speed up GDB
44752
44753@c man begin SYNOPSIS gdb-add-index
44754gdb-add-index @var{filename}
44755@c man end
44756
44757@c man begin DESCRIPTION gdb-add-index
44758When @value{GDBN} finds a symbol file, it scans the symbols in the
44759file in order to construct an internal symbol table. This lets most
44760@value{GDBN} operations work quickly--at the cost of a delay early on.
44761For large programs, this delay can be quite lengthy, so @value{GDBN}
44762provides a way to build an index, which speeds up startup.
44763
44764To determine whether a file contains such an index, use the command
44765@kbd{readelf -S filename}: the index is stored in a section named
44766@code{.gdb_index}. The index file can only be produced on systems
44767which use ELF binaries and DWARF debug information (i.e., sections
44768named @code{.debug_*}).
44769
44770@command{gdb-add-index} uses @value{GDBN} and @command{objdump} found
44771in the @env{PATH} environment variable. If you want to use different
44772versions of these programs, you can specify them through the
44773@env{GDB} and @env{OBJDUMP} environment variables.
44774
44775See more in
44776@ifset man
44777the @value{GDBN} manual in node @code{Index Files}
44778-- shell command @kbd{info -f gdb -n "Index Files"}.
44779@end ifset
44780@ifclear man
44781@ref{Index Files}.
44782@end ifclear
44783@c man end
44784
44785@c man begin SEEALSO gdb-add-index
44786@ifset man
44787The full documentation for @value{GDBN} is maintained as a Texinfo manual.
44788If the @code{info} and @code{gdb} programs and @value{GDBN}'s Texinfo
44789documentation are properly installed at your site, the command
43662968
JK
44790
44791@smallexample
44792info gdb
44793@end smallexample
44794
44795should give you access to the complete manual.
44796
44797@cite{Using GDB: A Guide to the GNU Source-Level Debugger},
44798Richard M. Stallman and Roland H. Pesch, July 1991.
44799@end ifset
44800@c man end
44801
aab4e0ec 44802@include gpl.texi
eb12ee30 44803
e4c0cfae
SS
44804@node GNU Free Documentation License
44805@appendix GNU Free Documentation License
6826cf00
EZ
44806@include fdl.texi
44807
00595b5e
EZ
44808@node Concept Index
44809@unnumbered Concept Index
c906108c
SS
44810
44811@printindex cp
44812
00595b5e
EZ
44813@node Command and Variable Index
44814@unnumbered Command, Variable, and Function Index
44815
44816@printindex fn
44817
c906108c 44818@tex
984359d2 44819% I think something like @@colophon should be in texinfo. In the
c906108c
SS
44820% meantime:
44821\long\def\colophon{\hbox to0pt{}\vfill
44822\centerline{The body of this manual is set in}
44823\centerline{\fontname\tenrm,}
44824\centerline{with headings in {\bf\fontname\tenbf}}
44825\centerline{and examples in {\tt\fontname\tentt}.}
44826\centerline{{\it\fontname\tenit\/},}
44827\centerline{{\bf\fontname\tenbf}, and}
44828\centerline{{\sl\fontname\tensl\/}}
44829\centerline{are used for emphasis.}\vfill}
44830\page\colophon
984359d2 44831% Blame: doc@@cygnus.com, 1991.
c906108c
SS
44832@end tex
44833
c906108c 44834@bye
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