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c906108c | 1 | \input texinfo @c -*-texinfo-*- |
b6ba6518 | 2 | @c Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, |
1e698235 | 3 | @c 1999, 2000, 2001, 2002, 2003 |
c906108c SS |
4 | @c Free Software Foundation, Inc. |
5 | @c | |
5d161b24 | 6 | @c %**start of header |
c906108c SS |
7 | @c makeinfo ignores cmds prev to setfilename, so its arg cannot make use |
8 | @c of @set vars. However, you can override filename with makeinfo -o. | |
9 | @setfilename gdb.info | |
10 | @c | |
11 | @include gdb-cfg.texi | |
12 | @c | |
c906108c | 13 | @settitle Debugging with @value{GDBN} |
c906108c SS |
14 | @setchapternewpage odd |
15 | @c %**end of header | |
16 | ||
17 | @iftex | |
18 | @c @smallbook | |
19 | @c @cropmarks | |
20 | @end iftex | |
21 | ||
22 | @finalout | |
23 | @syncodeindex ky cp | |
24 | ||
41afff9a | 25 | @c readline appendices use @vindex, @findex and @ftable, |
48e934c6 | 26 | @c annotate.texi and gdbmi use @findex. |
c906108c | 27 | @syncodeindex vr cp |
41afff9a | 28 | @syncodeindex fn cp |
c906108c SS |
29 | |
30 | @c !!set GDB manual's edition---not the same as GDB version! | |
e9c75b65 | 31 | @set EDITION Ninth |
c906108c SS |
32 | |
33 | @c !!set GDB manual's revision date | |
87885426 FN |
34 | @set DATE June 2002 |
35 | ||
36 | @c !!set GDB edit command default editor | |
37 | @set EDITOR /bin/ex | |
c906108c | 38 | |
6c0e9fb3 | 39 | @c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER. |
c906108c | 40 | |
c906108c | 41 | @c This is a dir.info fragment to support semi-automated addition of |
6d2ebf8b | 42 | @c manuals to an info tree. |
96a2c332 SS |
43 | @dircategory Programming & development tools. |
44 | @direntry | |
c906108c | 45 | * Gdb: (gdb). The @sc{gnu} debugger. |
96a2c332 SS |
46 | @end direntry |
47 | ||
c906108c SS |
48 | @ifinfo |
49 | This file documents the @sc{gnu} debugger @value{GDBN}. | |
50 | ||
51 | ||
5d161b24 | 52 | This is the @value{EDITION} Edition, @value{DATE}, |
c906108c SS |
53 | of @cite{Debugging with @value{GDBN}: the @sc{gnu} Source-Level Debugger} |
54 | for @value{GDBN} Version @value{GDBVN}. | |
55 | ||
8a037dd7 | 56 | Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,@* |
1e698235 | 57 | 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
c906108c | 58 | |
e9c75b65 EZ |
59 | Permission is granted to copy, distribute and/or modify this document |
60 | under the terms of the GNU Free Documentation License, Version 1.1 or | |
61 | any later version published by the Free Software Foundation; with the | |
959acfd1 EZ |
62 | Invariant Sections being ``Free Software'' and ``Free Software Needs |
63 | Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' | |
64 | and with the Back-Cover Texts as in (a) below. | |
c906108c | 65 | |
6826cf00 EZ |
66 | (a) The Free Software Foundation's Back-Cover Text is: ``You have |
67 | freedom to copy and modify this GNU Manual, like GNU software. Copies | |
68 | published by the Free Software Foundation raise funds for GNU | |
69 | development.'' | |
c906108c SS |
70 | @end ifinfo |
71 | ||
72 | @titlepage | |
73 | @title Debugging with @value{GDBN} | |
74 | @subtitle The @sc{gnu} Source-Level Debugger | |
c906108c | 75 | @sp 1 |
c906108c SS |
76 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
77 | @subtitle @value{DATE} | |
9e9c5ae7 | 78 | @author Richard Stallman, Roland Pesch, Stan Shebs, et al. |
c906108c | 79 | @page |
c906108c SS |
80 | @tex |
81 | {\parskip=0pt | |
53a5351d | 82 | \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@gnu.org.)\par |
c906108c SS |
83 | \hfill {\it Debugging with @value{GDBN}}\par |
84 | \hfill \TeX{}info \texinfoversion\par | |
85 | } | |
86 | @end tex | |
53a5351d | 87 | |
c906108c | 88 | @vskip 0pt plus 1filll |
8a037dd7 | 89 | Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, |
1e698235 | 90 | 1996, 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
c906108c | 91 | @sp 2 |
c906108c SS |
92 | Published by the Free Software Foundation @* |
93 | 59 Temple Place - Suite 330, @* | |
94 | Boston, MA 02111-1307 USA @* | |
6d2ebf8b | 95 | ISBN 1-882114-77-9 @* |
e9c75b65 EZ |
96 | |
97 | Permission is granted to copy, distribute and/or modify this document | |
98 | under the terms of the GNU Free Documentation License, Version 1.1 or | |
99 | any later version published by the Free Software Foundation; with the | |
959acfd1 EZ |
100 | Invariant Sections being ``Free Software'' and ``Free Software Needs |
101 | Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' | |
102 | and with the Back-Cover Texts as in (a) below. | |
e9c75b65 | 103 | |
6826cf00 EZ |
104 | (a) The Free Software Foundation's Back-Cover Text is: ``You have |
105 | freedom to copy and modify this GNU Manual, like GNU software. Copies | |
106 | published by the Free Software Foundation raise funds for GNU | |
107 | development.'' | |
c906108c SS |
108 | @end titlepage |
109 | @page | |
110 | ||
6c0e9fb3 | 111 | @ifnottex |
6d2ebf8b SS |
112 | @node Top, Summary, (dir), (dir) |
113 | ||
c906108c SS |
114 | @top Debugging with @value{GDBN} |
115 | ||
116 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. | |
117 | ||
5d161b24 | 118 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version |
c906108c SS |
119 | @value{GDBVN}. |
120 | ||
1e698235 | 121 | Copyright (C) 1988-2003 Free Software Foundation, Inc. |
6d2ebf8b SS |
122 | |
123 | @menu | |
124 | * Summary:: Summary of @value{GDBN} | |
125 | * Sample Session:: A sample @value{GDBN} session | |
126 | ||
127 | * Invocation:: Getting in and out of @value{GDBN} | |
128 | * Commands:: @value{GDBN} commands | |
129 | * Running:: Running programs under @value{GDBN} | |
130 | * Stopping:: Stopping and continuing | |
131 | * Stack:: Examining the stack | |
132 | * Source:: Examining source files | |
133 | * Data:: Examining data | |
e2e0bcd1 | 134 | * Macros:: Preprocessor Macros |
b37052ae | 135 | * Tracepoints:: Debugging remote targets non-intrusively |
df0cd8c5 | 136 | * Overlays:: Debugging programs that use overlays |
6d2ebf8b SS |
137 | |
138 | * Languages:: Using @value{GDBN} with different languages | |
139 | ||
140 | * Symbols:: Examining the symbol table | |
141 | * Altering:: Altering execution | |
142 | * GDB Files:: @value{GDBN} files | |
143 | * Targets:: Specifying a debugging target | |
6b2f586d | 144 | * Remote Debugging:: Debugging remote programs |
6d2ebf8b SS |
145 | * Configurations:: Configuration-specific information |
146 | * Controlling GDB:: Controlling @value{GDBN} | |
147 | * Sequences:: Canned sequences of commands | |
c4555f82 | 148 | * TUI:: @value{GDBN} Text User Interface |
21c294e6 | 149 | * Interpreters:: Command Interpreters |
6d2ebf8b SS |
150 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
151 | * Annotations:: @value{GDBN}'s annotation interface. | |
7162c0ca | 152 | * GDB/MI:: @value{GDBN}'s Machine Interface. |
6d2ebf8b SS |
153 | |
154 | * GDB Bugs:: Reporting bugs in @value{GDBN} | |
155 | * Formatting Documentation:: How to format and print @value{GDBN} documentation | |
156 | ||
157 | * Command Line Editing:: Command Line Editing | |
158 | * Using History Interactively:: Using History Interactively | |
159 | * Installing GDB:: Installing GDB | |
eb12ee30 | 160 | * Maintenance Commands:: Maintenance Commands |
e0ce93ac | 161 | * Remote Protocol:: GDB Remote Serial Protocol |
aab4e0ec AC |
162 | * Copying:: GNU General Public License says |
163 | how you can copy and share GDB | |
6826cf00 | 164 | * GNU Free Documentation License:: The license for this documentation |
6d2ebf8b SS |
165 | * Index:: Index |
166 | @end menu | |
167 | ||
6c0e9fb3 | 168 | @end ifnottex |
c906108c | 169 | |
449f3b6c | 170 | @contents |
449f3b6c | 171 | |
6d2ebf8b | 172 | @node Summary |
c906108c SS |
173 | @unnumbered Summary of @value{GDBN} |
174 | ||
175 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is | |
176 | going on ``inside'' another program while it executes---or what another | |
177 | program was doing at the moment it crashed. | |
178 | ||
179 | @value{GDBN} can do four main kinds of things (plus other things in support of | |
180 | these) to help you catch bugs in the act: | |
181 | ||
182 | @itemize @bullet | |
183 | @item | |
184 | Start your program, specifying anything that might affect its behavior. | |
185 | ||
186 | @item | |
187 | Make your program stop on specified conditions. | |
188 | ||
189 | @item | |
190 | Examine what has happened, when your program has stopped. | |
191 | ||
192 | @item | |
193 | Change things in your program, so you can experiment with correcting the | |
194 | effects of one bug and go on to learn about another. | |
195 | @end itemize | |
196 | ||
cce74817 | 197 | You can use @value{GDBN} to debug programs written in C and C++. |
c906108c | 198 | For more information, see @ref{Support,,Supported languages}. |
c906108c SS |
199 | For more information, see @ref{C,,C and C++}. |
200 | ||
cce74817 | 201 | @cindex Modula-2 |
e632838e AC |
202 | Support for Modula-2 is partial. For information on Modula-2, see |
203 | @ref{Modula-2,,Modula-2}. | |
c906108c | 204 | |
cce74817 JM |
205 | @cindex Pascal |
206 | Debugging Pascal programs which use sets, subranges, file variables, or | |
207 | nested functions does not currently work. @value{GDBN} does not support | |
208 | entering expressions, printing values, or similar features using Pascal | |
209 | syntax. | |
c906108c | 210 | |
c906108c SS |
211 | @cindex Fortran |
212 | @value{GDBN} can be used to debug programs written in Fortran, although | |
53a5351d | 213 | it may be necessary to refer to some variables with a trailing |
cce74817 | 214 | underscore. |
c906108c | 215 | |
c906108c SS |
216 | @menu |
217 | * Free Software:: Freely redistributable software | |
218 | * Contributors:: Contributors to GDB | |
219 | @end menu | |
220 | ||
6d2ebf8b | 221 | @node Free Software |
c906108c SS |
222 | @unnumberedsec Free software |
223 | ||
5d161b24 | 224 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} |
c906108c SS |
225 | General Public License |
226 | (GPL). The GPL gives you the freedom to copy or adapt a licensed | |
227 | program---but every person getting a copy also gets with it the | |
228 | freedom to modify that copy (which means that they must get access to | |
229 | the source code), and the freedom to distribute further copies. | |
230 | Typical software companies use copyrights to limit your freedoms; the | |
231 | Free Software Foundation uses the GPL to preserve these freedoms. | |
232 | ||
233 | Fundamentally, the General Public License is a license which says that | |
234 | you have these freedoms and that you cannot take these freedoms away | |
235 | from anyone else. | |
236 | ||
2666264b | 237 | @unnumberedsec Free Software Needs Free Documentation |
959acfd1 EZ |
238 | |
239 | The biggest deficiency in the free software community today is not in | |
240 | the software---it is the lack of good free documentation that we can | |
241 | include with the free software. Many of our most important | |
242 | programs do not come with free reference manuals and free introductory | |
243 | texts. Documentation is an essential part of any software package; | |
244 | when an important free software package does not come with a free | |
245 | manual and a free tutorial, that is a major gap. We have many such | |
246 | gaps today. | |
247 | ||
248 | Consider Perl, for instance. The tutorial manuals that people | |
249 | normally use are non-free. How did this come about? Because the | |
250 | authors of those manuals published them with restrictive terms---no | |
251 | copying, no modification, source files not available---which exclude | |
252 | them from the free software world. | |
253 | ||
254 | That wasn't the first time this sort of thing happened, and it was far | |
255 | from the last. Many times we have heard a GNU user eagerly describe a | |
256 | manual that he is writing, his intended contribution to the community, | |
257 | only to learn that he had ruined everything by signing a publication | |
258 | contract to make it non-free. | |
259 | ||
260 | Free documentation, like free software, is a matter of freedom, not | |
261 | price. The problem with the non-free manual is not that publishers | |
262 | charge a price for printed copies---that in itself is fine. (The Free | |
263 | Software Foundation sells printed copies of manuals, too.) The | |
264 | problem is the restrictions on the use of the manual. Free manuals | |
265 | are available in source code form, and give you permission to copy and | |
266 | modify. Non-free manuals do not allow this. | |
267 | ||
268 | The criteria of freedom for a free manual are roughly the same as for | |
269 | free software. Redistribution (including the normal kinds of | |
270 | commercial redistribution) must be permitted, so that the manual can | |
271 | accompany every copy of the program, both on-line and on paper. | |
272 | ||
273 | Permission for modification of the technical content is crucial too. | |
274 | When people modify the software, adding or changing features, if they | |
275 | are conscientious they will change the manual too---so they can | |
276 | provide accurate and clear documentation for the modified program. A | |
277 | manual that leaves you no choice but to write a new manual to document | |
278 | a changed version of the program is not really available to our | |
279 | community. | |
280 | ||
281 | Some kinds of limits on the way modification is handled are | |
282 | acceptable. For example, requirements to preserve the original | |
283 | author's copyright notice, the distribution terms, or the list of | |
284 | authors, are ok. It is also no problem to require modified versions | |
285 | to include notice that they were modified. Even entire sections that | |
286 | may not be deleted or changed are acceptable, as long as they deal | |
287 | with nontechnical topics (like this one). These kinds of restrictions | |
288 | are acceptable because they don't obstruct the community's normal use | |
289 | of the manual. | |
290 | ||
291 | However, it must be possible to modify all the @emph{technical} | |
292 | content of the manual, and then distribute the result in all the usual | |
293 | media, through all the usual channels. Otherwise, the restrictions | |
294 | obstruct the use of the manual, it is not free, and we need another | |
295 | manual to replace it. | |
296 | ||
297 | Please spread the word about this issue. Our community continues to | |
298 | lose manuals to proprietary publishing. If we spread the word that | |
299 | free software needs free reference manuals and free tutorials, perhaps | |
300 | the next person who wants to contribute by writing documentation will | |
301 | realize, before it is too late, that only free manuals contribute to | |
302 | the free software community. | |
303 | ||
304 | If you are writing documentation, please insist on publishing it under | |
305 | the GNU Free Documentation License or another free documentation | |
306 | license. Remember that this decision requires your approval---you | |
307 | don't have to let the publisher decide. Some commercial publishers | |
308 | will use a free license if you insist, but they will not propose the | |
309 | option; it is up to you to raise the issue and say firmly that this is | |
310 | what you want. If the publisher you are dealing with refuses, please | |
311 | try other publishers. If you're not sure whether a proposed license | |
42584a72 | 312 | is free, write to @email{licensing@@gnu.org}. |
959acfd1 EZ |
313 | |
314 | You can encourage commercial publishers to sell more free, copylefted | |
315 | manuals and tutorials by buying them, and particularly by buying | |
316 | copies from the publishers that paid for their writing or for major | |
317 | improvements. Meanwhile, try to avoid buying non-free documentation | |
318 | at all. Check the distribution terms of a manual before you buy it, | |
319 | and insist that whoever seeks your business must respect your freedom. | |
72c9928d EZ |
320 | Check the history of the book, and try to reward the publishers that |
321 | have paid or pay the authors to work on it. | |
959acfd1 EZ |
322 | |
323 | The Free Software Foundation maintains a list of free documentation | |
324 | published by other publishers, at | |
325 | @url{http://www.fsf.org/doc/other-free-books.html}. | |
326 | ||
6d2ebf8b | 327 | @node Contributors |
96a2c332 SS |
328 | @unnumberedsec Contributors to @value{GDBN} |
329 | ||
330 | Richard Stallman was the original author of @value{GDBN}, and of many | |
331 | other @sc{gnu} programs. Many others have contributed to its | |
332 | development. This section attempts to credit major contributors. One | |
333 | of the virtues of free software is that everyone is free to contribute | |
334 | to it; with regret, we cannot actually acknowledge everyone here. The | |
335 | file @file{ChangeLog} in the @value{GDBN} distribution approximates a | |
c906108c SS |
336 | blow-by-blow account. |
337 | ||
338 | Changes much prior to version 2.0 are lost in the mists of time. | |
339 | ||
340 | @quotation | |
341 | @emph{Plea:} Additions to this section are particularly welcome. If you | |
342 | or your friends (or enemies, to be evenhanded) have been unfairly | |
343 | omitted from this list, we would like to add your names! | |
344 | @end quotation | |
345 | ||
346 | So that they may not regard their many labors as thankless, we | |
347 | particularly thank those who shepherded @value{GDBN} through major | |
348 | releases: | |
299ffc64 | 349 | Andrew Cagney (releases 5.3, 5.2, 5.1 and 5.0); |
c906108c SS |
350 | Jim Blandy (release 4.18); |
351 | Jason Molenda (release 4.17); | |
352 | Stan Shebs (release 4.14); | |
353 | Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9); | |
354 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4); | |
355 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); | |
356 | Jim Kingdon (releases 3.5, 3.4, and 3.3); | |
357 | and Randy Smith (releases 3.2, 3.1, and 3.0). | |
358 | ||
359 | Richard Stallman, assisted at various times by Peter TerMaat, Chris | |
360 | Hanson, and Richard Mlynarik, handled releases through 2.8. | |
361 | ||
b37052ae EZ |
362 | Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support |
363 | in @value{GDBN}, with significant additional contributions from Per | |
364 | Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++} | |
365 | demangler. Early work on C@t{++} was by Peter TerMaat (who also did | |
366 | much general update work leading to release 3.0). | |
c906108c | 367 | |
b37052ae | 368 | @value{GDBN} uses the BFD subroutine library to examine multiple |
c906108c SS |
369 | object-file formats; BFD was a joint project of David V. |
370 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. | |
371 | ||
372 | David Johnson wrote the original COFF support; Pace Willison did | |
373 | the original support for encapsulated COFF. | |
374 | ||
0179ffac | 375 | Brent Benson of Harris Computer Systems contributed DWARF 2 support. |
c906108c SS |
376 | |
377 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. | |
378 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS | |
379 | support. | |
380 | Jean-Daniel Fekete contributed Sun 386i support. | |
381 | Chris Hanson improved the HP9000 support. | |
382 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. | |
383 | David Johnson contributed Encore Umax support. | |
384 | Jyrki Kuoppala contributed Altos 3068 support. | |
385 | Jeff Law contributed HP PA and SOM support. | |
386 | Keith Packard contributed NS32K support. | |
387 | Doug Rabson contributed Acorn Risc Machine support. | |
388 | Bob Rusk contributed Harris Nighthawk CX-UX support. | |
389 | Chris Smith contributed Convex support (and Fortran debugging). | |
390 | Jonathan Stone contributed Pyramid support. | |
391 | Michael Tiemann contributed SPARC support. | |
392 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. | |
393 | Pace Willison contributed Intel 386 support. | |
394 | Jay Vosburgh contributed Symmetry support. | |
a37295f9 | 395 | Marko Mlinar contributed OpenRISC 1000 support. |
c906108c | 396 | |
1104b9e7 | 397 | Andreas Schwab contributed M68K @sc{gnu}/Linux support. |
c906108c SS |
398 | |
399 | Rich Schaefer and Peter Schauer helped with support of SunOS shared | |
400 | libraries. | |
401 | ||
402 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree | |
403 | about several machine instruction sets. | |
404 | ||
405 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop | |
406 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM | |
407 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, | |
408 | and RDI targets, respectively. | |
409 | ||
410 | Brian Fox is the author of the readline libraries providing | |
411 | command-line editing and command history. | |
412 | ||
7a292a7a SS |
413 | Andrew Beers of SUNY Buffalo wrote the language-switching code, the |
414 | Modula-2 support, and contributed the Languages chapter of this manual. | |
c906108c | 415 | |
5d161b24 | 416 | Fred Fish wrote most of the support for Unix System Vr4. |
b37052ae | 417 | He also enhanced the command-completion support to cover C@t{++} overloaded |
c906108c | 418 | symbols. |
c906108c SS |
419 | |
420 | Hitachi America, Ltd. sponsored the support for H8/300, H8/500, and | |
421 | Super-H processors. | |
422 | ||
423 | NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors. | |
424 | ||
425 | Mitsubishi sponsored the support for D10V, D30V, and M32R/D processors. | |
426 | ||
427 | Toshiba sponsored the support for the TX39 Mips processor. | |
428 | ||
429 | Matsushita sponsored the support for the MN10200 and MN10300 processors. | |
430 | ||
96a2c332 | 431 | Fujitsu sponsored the support for SPARClite and FR30 processors. |
c906108c SS |
432 | |
433 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware | |
434 | watchpoints. | |
435 | ||
436 | Michael Snyder added support for tracepoints. | |
437 | ||
438 | Stu Grossman wrote gdbserver. | |
439 | ||
440 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made | |
96a2c332 | 441 | nearly innumerable bug fixes and cleanups throughout @value{GDBN}. |
c906108c SS |
442 | |
443 | The following people at the Hewlett-Packard Company contributed | |
444 | support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0 | |
b37052ae | 445 | (narrow mode), HP's implementation of kernel threads, HP's aC@t{++} |
c906108c SS |
446 | compiler, and the terminal user interface: Ben Krepp, Richard Title, |
447 | John Bishop, Susan Macchia, Kathy Mann, Satish Pai, India Paul, Steve | |
448 | Rehrauer, and Elena Zannoni. Kim Haase provided HP-specific | |
449 | information in this manual. | |
450 | ||
b37052ae EZ |
451 | DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project. |
452 | Robert Hoehne made significant contributions to the DJGPP port. | |
453 | ||
96a2c332 SS |
454 | Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its |
455 | development since 1991. Cygnus engineers who have worked on @value{GDBN} | |
2df3850c JM |
456 | fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin |
457 | Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim | |
458 | Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler, | |
459 | Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek | |
460 | Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In | |
461 | addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton, | |
462 | JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug | |
463 | Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff | |
464 | Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner, | |
465 | Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin | |
466 | Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela | |
467 | Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David | |
468 | Zuhn have made contributions both large and small. | |
c906108c | 469 | |
e2e0bcd1 JB |
470 | Jim Blandy added support for preprocessor macros, while working for Red |
471 | Hat. | |
c906108c | 472 | |
6d2ebf8b | 473 | @node Sample Session |
c906108c SS |
474 | @chapter A Sample @value{GDBN} Session |
475 | ||
476 | You can use this manual at your leisure to read all about @value{GDBN}. | |
477 | However, a handful of commands are enough to get started using the | |
478 | debugger. This chapter illustrates those commands. | |
479 | ||
480 | @iftex | |
481 | In this sample session, we emphasize user input like this: @b{input}, | |
482 | to make it easier to pick out from the surrounding output. | |
483 | @end iftex | |
484 | ||
485 | @c FIXME: this example may not be appropriate for some configs, where | |
486 | @c FIXME...primary interest is in remote use. | |
487 | ||
488 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro | |
489 | processor) exhibits the following bug: sometimes, when we change its | |
490 | quote strings from the default, the commands used to capture one macro | |
491 | definition within another stop working. In the following short @code{m4} | |
492 | session, we define a macro @code{foo} which expands to @code{0000}; we | |
493 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the | |
494 | same thing. However, when we change the open quote string to | |
495 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same | |
496 | procedure fails to define a new synonym @code{baz}: | |
497 | ||
498 | @smallexample | |
499 | $ @b{cd gnu/m4} | |
500 | $ @b{./m4} | |
501 | @b{define(foo,0000)} | |
502 | ||
503 | @b{foo} | |
504 | 0000 | |
505 | @b{define(bar,defn(`foo'))} | |
506 | ||
507 | @b{bar} | |
508 | 0000 | |
509 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
510 | ||
511 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
512 | @b{baz} | |
513 | @b{C-d} | |
514 | m4: End of input: 0: fatal error: EOF in string | |
515 | @end smallexample | |
516 | ||
517 | @noindent | |
518 | Let us use @value{GDBN} to try to see what is going on. | |
519 | ||
c906108c SS |
520 | @smallexample |
521 | $ @b{@value{GDBP} m4} | |
522 | @c FIXME: this falsifies the exact text played out, to permit smallbook | |
523 | @c FIXME... format to come out better. | |
524 | @value{GDBN} is free software and you are welcome to distribute copies | |
5d161b24 | 525 | of it under certain conditions; type "show copying" to see |
c906108c | 526 | the conditions. |
5d161b24 | 527 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
c906108c SS |
528 | for details. |
529 | ||
530 | @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc... | |
531 | (@value{GDBP}) | |
532 | @end smallexample | |
c906108c SS |
533 | |
534 | @noindent | |
535 | @value{GDBN} reads only enough symbol data to know where to find the | |
536 | rest when needed; as a result, the first prompt comes up very quickly. | |
537 | We now tell @value{GDBN} to use a narrower display width than usual, so | |
538 | that examples fit in this manual. | |
539 | ||
540 | @smallexample | |
541 | (@value{GDBP}) @b{set width 70} | |
542 | @end smallexample | |
543 | ||
544 | @noindent | |
545 | We need to see how the @code{m4} built-in @code{changequote} works. | |
546 | Having looked at the source, we know the relevant subroutine is | |
547 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} | |
548 | @code{break} command. | |
549 | ||
550 | @smallexample | |
551 | (@value{GDBP}) @b{break m4_changequote} | |
552 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. | |
553 | @end smallexample | |
554 | ||
555 | @noindent | |
556 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} | |
557 | control; as long as control does not reach the @code{m4_changequote} | |
558 | subroutine, the program runs as usual: | |
559 | ||
560 | @smallexample | |
561 | (@value{GDBP}) @b{run} | |
562 | Starting program: /work/Editorial/gdb/gnu/m4/m4 | |
563 | @b{define(foo,0000)} | |
564 | ||
565 | @b{foo} | |
566 | 0000 | |
567 | @end smallexample | |
568 | ||
569 | @noindent | |
570 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} | |
571 | suspends execution of @code{m4}, displaying information about the | |
572 | context where it stops. | |
573 | ||
574 | @smallexample | |
575 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
576 | ||
5d161b24 | 577 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) |
c906108c SS |
578 | at builtin.c:879 |
579 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) | |
580 | @end smallexample | |
581 | ||
582 | @noindent | |
583 | Now we use the command @code{n} (@code{next}) to advance execution to | |
584 | the next line of the current function. | |
585 | ||
586 | @smallexample | |
587 | (@value{GDBP}) @b{n} | |
588 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ | |
589 | : nil, | |
590 | @end smallexample | |
591 | ||
592 | @noindent | |
593 | @code{set_quotes} looks like a promising subroutine. We can go into it | |
594 | by using the command @code{s} (@code{step}) instead of @code{next}. | |
595 | @code{step} goes to the next line to be executed in @emph{any} | |
596 | subroutine, so it steps into @code{set_quotes}. | |
597 | ||
598 | @smallexample | |
599 | (@value{GDBP}) @b{s} | |
600 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
601 | at input.c:530 | |
602 | 530 if (lquote != def_lquote) | |
603 | @end smallexample | |
604 | ||
605 | @noindent | |
606 | The display that shows the subroutine where @code{m4} is now | |
607 | suspended (and its arguments) is called a stack frame display. It | |
608 | shows a summary of the stack. We can use the @code{backtrace} | |
609 | command (which can also be spelled @code{bt}), to see where we are | |
610 | in the stack as a whole: the @code{backtrace} command displays a | |
611 | stack frame for each active subroutine. | |
612 | ||
613 | @smallexample | |
614 | (@value{GDBP}) @b{bt} | |
615 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
616 | at input.c:530 | |
5d161b24 | 617 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) |
c906108c SS |
618 | at builtin.c:882 |
619 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 | |
620 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) | |
621 | at macro.c:71 | |
622 | #4 0x79dc in expand_input () at macro.c:40 | |
623 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 | |
624 | @end smallexample | |
625 | ||
626 | @noindent | |
627 | We step through a few more lines to see what happens. The first two | |
628 | times, we can use @samp{s}; the next two times we use @code{n} to avoid | |
629 | falling into the @code{xstrdup} subroutine. | |
630 | ||
631 | @smallexample | |
632 | (@value{GDBP}) @b{s} | |
633 | 0x3b5c 532 if (rquote != def_rquote) | |
634 | (@value{GDBP}) @b{s} | |
635 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ | |
636 | def_lquote : xstrdup(lq); | |
637 | (@value{GDBP}) @b{n} | |
638 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
639 | : xstrdup(rq); | |
640 | (@value{GDBP}) @b{n} | |
641 | 538 len_lquote = strlen(rquote); | |
642 | @end smallexample | |
643 | ||
644 | @noindent | |
645 | The last line displayed looks a little odd; we can examine the variables | |
646 | @code{lquote} and @code{rquote} to see if they are in fact the new left | |
647 | and right quotes we specified. We use the command @code{p} | |
648 | (@code{print}) to see their values. | |
649 | ||
650 | @smallexample | |
651 | (@value{GDBP}) @b{p lquote} | |
652 | $1 = 0x35d40 "<QUOTE>" | |
653 | (@value{GDBP}) @b{p rquote} | |
654 | $2 = 0x35d50 "<UNQUOTE>" | |
655 | @end smallexample | |
656 | ||
657 | @noindent | |
658 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. | |
659 | To look at some context, we can display ten lines of source | |
660 | surrounding the current line with the @code{l} (@code{list}) command. | |
661 | ||
662 | @smallexample | |
663 | (@value{GDBP}) @b{l} | |
664 | 533 xfree(rquote); | |
665 | 534 | |
666 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ | |
667 | : xstrdup (lq); | |
668 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
669 | : xstrdup (rq); | |
670 | 537 | |
671 | 538 len_lquote = strlen(rquote); | |
672 | 539 len_rquote = strlen(lquote); | |
673 | 540 @} | |
674 | 541 | |
675 | 542 void | |
676 | @end smallexample | |
677 | ||
678 | @noindent | |
679 | Let us step past the two lines that set @code{len_lquote} and | |
680 | @code{len_rquote}, and then examine the values of those variables. | |
681 | ||
682 | @smallexample | |
683 | (@value{GDBP}) @b{n} | |
684 | 539 len_rquote = strlen(lquote); | |
685 | (@value{GDBP}) @b{n} | |
686 | 540 @} | |
687 | (@value{GDBP}) @b{p len_lquote} | |
688 | $3 = 9 | |
689 | (@value{GDBP}) @b{p len_rquote} | |
690 | $4 = 7 | |
691 | @end smallexample | |
692 | ||
693 | @noindent | |
694 | That certainly looks wrong, assuming @code{len_lquote} and | |
695 | @code{len_rquote} are meant to be the lengths of @code{lquote} and | |
696 | @code{rquote} respectively. We can set them to better values using | |
697 | the @code{p} command, since it can print the value of | |
698 | any expression---and that expression can include subroutine calls and | |
699 | assignments. | |
700 | ||
701 | @smallexample | |
702 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} | |
703 | $5 = 7 | |
704 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} | |
705 | $6 = 9 | |
706 | @end smallexample | |
707 | ||
708 | @noindent | |
709 | Is that enough to fix the problem of using the new quotes with the | |
710 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue | |
711 | executing with the @code{c} (@code{continue}) command, and then try the | |
712 | example that caused trouble initially: | |
713 | ||
714 | @smallexample | |
715 | (@value{GDBP}) @b{c} | |
716 | Continuing. | |
717 | ||
718 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
719 | ||
720 | baz | |
721 | 0000 | |
722 | @end smallexample | |
723 | ||
724 | @noindent | |
725 | Success! The new quotes now work just as well as the default ones. The | |
726 | problem seems to have been just the two typos defining the wrong | |
727 | lengths. We allow @code{m4} exit by giving it an EOF as input: | |
728 | ||
729 | @smallexample | |
730 | @b{C-d} | |
731 | Program exited normally. | |
732 | @end smallexample | |
733 | ||
734 | @noindent | |
735 | The message @samp{Program exited normally.} is from @value{GDBN}; it | |
736 | indicates @code{m4} has finished executing. We can end our @value{GDBN} | |
737 | session with the @value{GDBN} @code{quit} command. | |
738 | ||
739 | @smallexample | |
740 | (@value{GDBP}) @b{quit} | |
741 | @end smallexample | |
c906108c | 742 | |
6d2ebf8b | 743 | @node Invocation |
c906108c SS |
744 | @chapter Getting In and Out of @value{GDBN} |
745 | ||
746 | This chapter discusses how to start @value{GDBN}, and how to get out of it. | |
5d161b24 | 747 | The essentials are: |
c906108c | 748 | @itemize @bullet |
5d161b24 | 749 | @item |
53a5351d | 750 | type @samp{@value{GDBP}} to start @value{GDBN}. |
5d161b24 | 751 | @item |
c906108c SS |
752 | type @kbd{quit} or @kbd{C-d} to exit. |
753 | @end itemize | |
754 | ||
755 | @menu | |
756 | * Invoking GDB:: How to start @value{GDBN} | |
757 | * Quitting GDB:: How to quit @value{GDBN} | |
758 | * Shell Commands:: How to use shell commands inside @value{GDBN} | |
759 | @end menu | |
760 | ||
6d2ebf8b | 761 | @node Invoking GDB |
c906108c SS |
762 | @section Invoking @value{GDBN} |
763 | ||
c906108c SS |
764 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
765 | @value{GDBN} reads commands from the terminal until you tell it to exit. | |
766 | ||
767 | You can also run @code{@value{GDBP}} with a variety of arguments and options, | |
768 | to specify more of your debugging environment at the outset. | |
769 | ||
c906108c SS |
770 | The command-line options described here are designed |
771 | to cover a variety of situations; in some environments, some of these | |
5d161b24 | 772 | options may effectively be unavailable. |
c906108c SS |
773 | |
774 | The most usual way to start @value{GDBN} is with one argument, | |
775 | specifying an executable program: | |
776 | ||
474c8240 | 777 | @smallexample |
c906108c | 778 | @value{GDBP} @var{program} |
474c8240 | 779 | @end smallexample |
c906108c | 780 | |
c906108c SS |
781 | @noindent |
782 | You can also start with both an executable program and a core file | |
783 | specified: | |
784 | ||
474c8240 | 785 | @smallexample |
c906108c | 786 | @value{GDBP} @var{program} @var{core} |
474c8240 | 787 | @end smallexample |
c906108c SS |
788 | |
789 | You can, instead, specify a process ID as a second argument, if you want | |
790 | to debug a running process: | |
791 | ||
474c8240 | 792 | @smallexample |
c906108c | 793 | @value{GDBP} @var{program} 1234 |
474c8240 | 794 | @end smallexample |
c906108c SS |
795 | |
796 | @noindent | |
797 | would attach @value{GDBN} to process @code{1234} (unless you also have a file | |
798 | named @file{1234}; @value{GDBN} does check for a core file first). | |
799 | ||
c906108c | 800 | Taking advantage of the second command-line argument requires a fairly |
2df3850c JM |
801 | complete operating system; when you use @value{GDBN} as a remote |
802 | debugger attached to a bare board, there may not be any notion of | |
803 | ``process'', and there is often no way to get a core dump. @value{GDBN} | |
804 | will warn you if it is unable to attach or to read core dumps. | |
c906108c | 805 | |
aa26fa3a TT |
806 | You can optionally have @code{@value{GDBP}} pass any arguments after the |
807 | executable file to the inferior using @code{--args}. This option stops | |
808 | option processing. | |
474c8240 | 809 | @smallexample |
aa26fa3a | 810 | gdb --args gcc -O2 -c foo.c |
474c8240 | 811 | @end smallexample |
aa26fa3a TT |
812 | This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set |
813 | @code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}. | |
814 | ||
96a2c332 | 815 | You can run @code{@value{GDBP}} without printing the front material, which describes |
c906108c SS |
816 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: |
817 | ||
818 | @smallexample | |
819 | @value{GDBP} -silent | |
820 | @end smallexample | |
821 | ||
822 | @noindent | |
823 | You can further control how @value{GDBN} starts up by using command-line | |
824 | options. @value{GDBN} itself can remind you of the options available. | |
825 | ||
826 | @noindent | |
827 | Type | |
828 | ||
474c8240 | 829 | @smallexample |
c906108c | 830 | @value{GDBP} -help |
474c8240 | 831 | @end smallexample |
c906108c SS |
832 | |
833 | @noindent | |
834 | to display all available options and briefly describe their use | |
835 | (@samp{@value{GDBP} -h} is a shorter equivalent). | |
836 | ||
837 | All options and command line arguments you give are processed | |
838 | in sequential order. The order makes a difference when the | |
839 | @samp{-x} option is used. | |
840 | ||
841 | ||
842 | @menu | |
c906108c SS |
843 | * File Options:: Choosing files |
844 | * Mode Options:: Choosing modes | |
845 | @end menu | |
846 | ||
6d2ebf8b | 847 | @node File Options |
c906108c SS |
848 | @subsection Choosing files |
849 | ||
2df3850c | 850 | When @value{GDBN} starts, it reads any arguments other than options as |
c906108c SS |
851 | specifying an executable file and core file (or process ID). This is |
852 | the same as if the arguments were specified by the @samp{-se} and | |
19837790 MS |
853 | @samp{-c} (or @samp{-p} options respectively. (@value{GDBN} reads the |
854 | first argument that does not have an associated option flag as | |
855 | equivalent to the @samp{-se} option followed by that argument; and the | |
856 | second argument that does not have an associated option flag, if any, as | |
857 | equivalent to the @samp{-c}/@samp{-p} option followed by that argument.) | |
858 | If the second argument begins with a decimal digit, @value{GDBN} will | |
859 | first attempt to attach to it as a process, and if that fails, attempt | |
860 | to open it as a corefile. If you have a corefile whose name begins with | |
861 | a digit, you can prevent @value{GDBN} from treating it as a pid by | |
79f12247 | 862 | prefixing it with @file{./}, eg. @file{./12345}. |
7a292a7a SS |
863 | |
864 | If @value{GDBN} has not been configured to included core file support, | |
865 | such as for most embedded targets, then it will complain about a second | |
866 | argument and ignore it. | |
c906108c SS |
867 | |
868 | Many options have both long and short forms; both are shown in the | |
869 | following list. @value{GDBN} also recognizes the long forms if you truncate | |
870 | them, so long as enough of the option is present to be unambiguous. | |
871 | (If you prefer, you can flag option arguments with @samp{--} rather | |
872 | than @samp{-}, though we illustrate the more usual convention.) | |
873 | ||
d700128c EZ |
874 | @c NOTE: the @cindex entries here use double dashes ON PURPOSE. This |
875 | @c way, both those who look for -foo and --foo in the index, will find | |
876 | @c it. | |
877 | ||
c906108c SS |
878 | @table @code |
879 | @item -symbols @var{file} | |
880 | @itemx -s @var{file} | |
d700128c EZ |
881 | @cindex @code{--symbols} |
882 | @cindex @code{-s} | |
c906108c SS |
883 | Read symbol table from file @var{file}. |
884 | ||
885 | @item -exec @var{file} | |
886 | @itemx -e @var{file} | |
d700128c EZ |
887 | @cindex @code{--exec} |
888 | @cindex @code{-e} | |
7a292a7a SS |
889 | Use file @var{file} as the executable file to execute when appropriate, |
890 | and for examining pure data in conjunction with a core dump. | |
c906108c SS |
891 | |
892 | @item -se @var{file} | |
d700128c | 893 | @cindex @code{--se} |
c906108c SS |
894 | Read symbol table from file @var{file} and use it as the executable |
895 | file. | |
896 | ||
c906108c SS |
897 | @item -core @var{file} |
898 | @itemx -c @var{file} | |
d700128c EZ |
899 | @cindex @code{--core} |
900 | @cindex @code{-c} | |
19837790 | 901 | Use file @var{file} as a core dump to examine. |
c906108c SS |
902 | |
903 | @item -c @var{number} | |
19837790 MS |
904 | @item -pid @var{number} |
905 | @itemx -p @var{number} | |
906 | @cindex @code{--pid} | |
907 | @cindex @code{-p} | |
908 | Connect to process ID @var{number}, as with the @code{attach} command. | |
909 | If there is no such process, @value{GDBN} will attempt to open a core | |
910 | file named @var{number}. | |
c906108c SS |
911 | |
912 | @item -command @var{file} | |
913 | @itemx -x @var{file} | |
d700128c EZ |
914 | @cindex @code{--command} |
915 | @cindex @code{-x} | |
c906108c SS |
916 | Execute @value{GDBN} commands from file @var{file}. @xref{Command |
917 | Files,, Command files}. | |
918 | ||
919 | @item -directory @var{directory} | |
920 | @itemx -d @var{directory} | |
d700128c EZ |
921 | @cindex @code{--directory} |
922 | @cindex @code{-d} | |
c906108c SS |
923 | Add @var{directory} to the path to search for source files. |
924 | ||
c906108c SS |
925 | @item -m |
926 | @itemx -mapped | |
d700128c EZ |
927 | @cindex @code{--mapped} |
928 | @cindex @code{-m} | |
c906108c SS |
929 | @emph{Warning: this option depends on operating system facilities that are not |
930 | supported on all systems.}@* | |
931 | If memory-mapped files are available on your system through the @code{mmap} | |
5d161b24 | 932 | system call, you can use this option |
c906108c SS |
933 | to have @value{GDBN} write the symbols from your |
934 | program into a reusable file in the current directory. If the program you are debugging is | |
96a2c332 | 935 | called @file{/tmp/fred}, the mapped symbol file is @file{/tmp/fred.syms}. |
c906108c SS |
936 | Future @value{GDBN} debugging sessions notice the presence of this file, |
937 | and can quickly map in symbol information from it, rather than reading | |
938 | the symbol table from the executable program. | |
939 | ||
940 | The @file{.syms} file is specific to the host machine where @value{GDBN} | |
941 | is run. It holds an exact image of the internal @value{GDBN} symbol | |
942 | table. It cannot be shared across multiple host platforms. | |
c906108c | 943 | |
c906108c SS |
944 | @item -r |
945 | @itemx -readnow | |
d700128c EZ |
946 | @cindex @code{--readnow} |
947 | @cindex @code{-r} | |
c906108c SS |
948 | Read each symbol file's entire symbol table immediately, rather than |
949 | the default, which is to read it incrementally as it is needed. | |
950 | This makes startup slower, but makes future operations faster. | |
53a5351d | 951 | |
c906108c SS |
952 | @end table |
953 | ||
2df3850c | 954 | You typically combine the @code{-mapped} and @code{-readnow} options in |
c906108c | 955 | order to build a @file{.syms} file that contains complete symbol |
2df3850c JM |
956 | information. (@xref{Files,,Commands to specify files}, for information |
957 | on @file{.syms} files.) A simple @value{GDBN} invocation to do nothing | |
958 | but build a @file{.syms} file for future use is: | |
c906108c | 959 | |
474c8240 | 960 | @smallexample |
2df3850c | 961 | gdb -batch -nx -mapped -readnow programname |
474c8240 | 962 | @end smallexample |
c906108c | 963 | |
6d2ebf8b | 964 | @node Mode Options |
c906108c SS |
965 | @subsection Choosing modes |
966 | ||
967 | You can run @value{GDBN} in various alternative modes---for example, in | |
968 | batch mode or quiet mode. | |
969 | ||
970 | @table @code | |
971 | @item -nx | |
972 | @itemx -n | |
d700128c EZ |
973 | @cindex @code{--nx} |
974 | @cindex @code{-n} | |
96565e91 | 975 | Do not execute commands found in any initialization files. Normally, |
2df3850c JM |
976 | @value{GDBN} executes the commands in these files after all the command |
977 | options and arguments have been processed. @xref{Command Files,,Command | |
978 | files}. | |
c906108c SS |
979 | |
980 | @item -quiet | |
d700128c | 981 | @itemx -silent |
c906108c | 982 | @itemx -q |
d700128c EZ |
983 | @cindex @code{--quiet} |
984 | @cindex @code{--silent} | |
985 | @cindex @code{-q} | |
c906108c SS |
986 | ``Quiet''. Do not print the introductory and copyright messages. These |
987 | messages are also suppressed in batch mode. | |
988 | ||
989 | @item -batch | |
d700128c | 990 | @cindex @code{--batch} |
c906108c SS |
991 | Run in batch mode. Exit with status @code{0} after processing all the |
992 | command files specified with @samp{-x} (and all commands from | |
993 | initialization files, if not inhibited with @samp{-n}). Exit with | |
994 | nonzero status if an error occurs in executing the @value{GDBN} commands | |
995 | in the command files. | |
996 | ||
2df3850c JM |
997 | Batch mode may be useful for running @value{GDBN} as a filter, for |
998 | example to download and run a program on another computer; in order to | |
999 | make this more useful, the message | |
c906108c | 1000 | |
474c8240 | 1001 | @smallexample |
c906108c | 1002 | Program exited normally. |
474c8240 | 1003 | @end smallexample |
c906108c SS |
1004 | |
1005 | @noindent | |
2df3850c JM |
1006 | (which is ordinarily issued whenever a program running under |
1007 | @value{GDBN} control terminates) is not issued when running in batch | |
1008 | mode. | |
1009 | ||
1010 | @item -nowindows | |
1011 | @itemx -nw | |
d700128c EZ |
1012 | @cindex @code{--nowindows} |
1013 | @cindex @code{-nw} | |
2df3850c | 1014 | ``No windows''. If @value{GDBN} comes with a graphical user interface |
96a2c332 | 1015 | (GUI) built in, then this option tells @value{GDBN} to only use the command-line |
2df3850c JM |
1016 | interface. If no GUI is available, this option has no effect. |
1017 | ||
1018 | @item -windows | |
1019 | @itemx -w | |
d700128c EZ |
1020 | @cindex @code{--windows} |
1021 | @cindex @code{-w} | |
2df3850c JM |
1022 | If @value{GDBN} includes a GUI, then this option requires it to be |
1023 | used if possible. | |
c906108c SS |
1024 | |
1025 | @item -cd @var{directory} | |
d700128c | 1026 | @cindex @code{--cd} |
c906108c SS |
1027 | Run @value{GDBN} using @var{directory} as its working directory, |
1028 | instead of the current directory. | |
1029 | ||
c906108c SS |
1030 | @item -fullname |
1031 | @itemx -f | |
d700128c EZ |
1032 | @cindex @code{--fullname} |
1033 | @cindex @code{-f} | |
7a292a7a SS |
1034 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a |
1035 | subprocess. It tells @value{GDBN} to output the full file name and line | |
1036 | number in a standard, recognizable fashion each time a stack frame is | |
1037 | displayed (which includes each time your program stops). This | |
1038 | recognizable format looks like two @samp{\032} characters, followed by | |
1039 | the file name, line number and character position separated by colons, | |
1040 | and a newline. The Emacs-to-@value{GDBN} interface program uses the two | |
1041 | @samp{\032} characters as a signal to display the source code for the | |
1042 | frame. | |
c906108c | 1043 | |
d700128c EZ |
1044 | @item -epoch |
1045 | @cindex @code{--epoch} | |
1046 | The Epoch Emacs-@value{GDBN} interface sets this option when it runs | |
1047 | @value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print | |
1048 | routines so as to allow Epoch to display values of expressions in a | |
1049 | separate window. | |
1050 | ||
1051 | @item -annotate @var{level} | |
1052 | @cindex @code{--annotate} | |
1053 | This option sets the @dfn{annotation level} inside @value{GDBN}. Its | |
1054 | effect is identical to using @samp{set annotate @var{level}} | |
1055 | (@pxref{Annotations}). | |
1056 | Annotation level controls how much information does @value{GDBN} print | |
1057 | together with its prompt, values of expressions, source lines, and other | |
1058 | types of output. Level 0 is the normal, level 1 is for use when | |
1059 | @value{GDBN} is run as a subprocess of @sc{gnu} Emacs, level 2 is the | |
1060 | maximum annotation suitable for programs that control @value{GDBN}. | |
1061 | ||
1062 | @item -async | |
1063 | @cindex @code{--async} | |
1064 | Use the asynchronous event loop for the command-line interface. | |
1065 | @value{GDBN} processes all events, such as user keyboard input, via a | |
1066 | special event loop. This allows @value{GDBN} to accept and process user | |
1067 | commands in parallel with the debugged process being | |
1068 | run@footnote{@value{GDBN} built with @sc{djgpp} tools for | |
1069 | MS-DOS/MS-Windows supports this mode of operation, but the event loop is | |
1070 | suspended when the debuggee runs.}, so you don't need to wait for | |
1071 | control to return to @value{GDBN} before you type the next command. | |
b37052ae | 1072 | (@emph{Note:} as of version 5.1, the target side of the asynchronous |
d700128c EZ |
1073 | operation is not yet in place, so @samp{-async} does not work fully |
1074 | yet.) | |
1075 | @c FIXME: when the target side of the event loop is done, the above NOTE | |
1076 | @c should be removed. | |
1077 | ||
1078 | When the standard input is connected to a terminal device, @value{GDBN} | |
1079 | uses the asynchronous event loop by default, unless disabled by the | |
1080 | @samp{-noasync} option. | |
1081 | ||
1082 | @item -noasync | |
1083 | @cindex @code{--noasync} | |
1084 | Disable the asynchronous event loop for the command-line interface. | |
1085 | ||
aa26fa3a TT |
1086 | @item --args |
1087 | @cindex @code{--args} | |
1088 | Change interpretation of command line so that arguments following the | |
1089 | executable file are passed as command line arguments to the inferior. | |
1090 | This option stops option processing. | |
1091 | ||
2df3850c JM |
1092 | @item -baud @var{bps} |
1093 | @itemx -b @var{bps} | |
d700128c EZ |
1094 | @cindex @code{--baud} |
1095 | @cindex @code{-b} | |
c906108c SS |
1096 | Set the line speed (baud rate or bits per second) of any serial |
1097 | interface used by @value{GDBN} for remote debugging. | |
c906108c SS |
1098 | |
1099 | @item -tty @var{device} | |
d700128c EZ |
1100 | @itemx -t @var{device} |
1101 | @cindex @code{--tty} | |
1102 | @cindex @code{-t} | |
c906108c SS |
1103 | Run using @var{device} for your program's standard input and output. |
1104 | @c FIXME: kingdon thinks there is more to -tty. Investigate. | |
c906108c | 1105 | |
53a5351d | 1106 | @c resolve the situation of these eventually |
c4555f82 SC |
1107 | @item -tui |
1108 | @cindex @code{--tui} | |
1109 | Activate the Terminal User Interface when starting. | |
1110 | The Terminal User Interface manages several text windows on the terminal, | |
1111 | showing source, assembly, registers and @value{GDBN} command outputs | |
1112 | (@pxref{TUI, ,@value{GDBN} Text User Interface}). | |
1113 | Do not use this option if you run @value{GDBN} from Emacs | |
1114 | (@pxref{Emacs, ,Using @value{GDBN} under @sc{gnu} Emacs}). | |
53a5351d JM |
1115 | |
1116 | @c @item -xdb | |
d700128c | 1117 | @c @cindex @code{--xdb} |
53a5351d JM |
1118 | @c Run in XDB compatibility mode, allowing the use of certain XDB commands. |
1119 | @c For information, see the file @file{xdb_trans.html}, which is usually | |
1120 | @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX | |
1121 | @c systems. | |
1122 | ||
d700128c EZ |
1123 | @item -interpreter @var{interp} |
1124 | @cindex @code{--interpreter} | |
1125 | Use the interpreter @var{interp} for interface with the controlling | |
1126 | program or device. This option is meant to be set by programs which | |
94bbb2c0 | 1127 | communicate with @value{GDBN} using it as a back end. |
21c294e6 | 1128 | @xref{Interpreters, , Command Interpreters}. |
94bbb2c0 | 1129 | |
da0f9dcd AC |
1130 | @samp{--interpreter=mi} (or @samp{--interpreter=mi2}) causes |
1131 | @value{GDBN} to use the current @dfn{@sc{gdb/mi} interface} | |
1132 | (@pxref{GDB/MI, , The @sc{gdb/mi} Interface}). The previous @sc{gdb/mi} | |
1133 | interface, included in @value{GDBN} version 5.3, can be selected with | |
1134 | @samp{--interpreter=mi1}. Earlier @sc{gdb/mi} interfaces | |
1135 | are not supported. | |
d700128c EZ |
1136 | |
1137 | @item -write | |
1138 | @cindex @code{--write} | |
1139 | Open the executable and core files for both reading and writing. This | |
1140 | is equivalent to the @samp{set write on} command inside @value{GDBN} | |
1141 | (@pxref{Patching}). | |
1142 | ||
1143 | @item -statistics | |
1144 | @cindex @code{--statistics} | |
1145 | This option causes @value{GDBN} to print statistics about time and | |
1146 | memory usage after it completes each command and returns to the prompt. | |
1147 | ||
1148 | @item -version | |
1149 | @cindex @code{--version} | |
1150 | This option causes @value{GDBN} to print its version number and | |
1151 | no-warranty blurb, and exit. | |
1152 | ||
c906108c SS |
1153 | @end table |
1154 | ||
6d2ebf8b | 1155 | @node Quitting GDB |
c906108c SS |
1156 | @section Quitting @value{GDBN} |
1157 | @cindex exiting @value{GDBN} | |
1158 | @cindex leaving @value{GDBN} | |
1159 | ||
1160 | @table @code | |
1161 | @kindex quit @r{[}@var{expression}@r{]} | |
41afff9a | 1162 | @kindex q @r{(@code{quit})} |
96a2c332 SS |
1163 | @item quit @r{[}@var{expression}@r{]} |
1164 | @itemx q | |
1165 | To exit @value{GDBN}, use the @code{quit} command (abbreviated | |
1166 | @code{q}), or type an end-of-file character (usually @kbd{C-d}). If you | |
1167 | do not supply @var{expression}, @value{GDBN} will terminate normally; | |
1168 | otherwise it will terminate using the result of @var{expression} as the | |
1169 | error code. | |
c906108c SS |
1170 | @end table |
1171 | ||
1172 | @cindex interrupt | |
1173 | An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather | |
1174 | terminates the action of any @value{GDBN} command that is in progress and | |
1175 | returns to @value{GDBN} command level. It is safe to type the interrupt | |
1176 | character at any time because @value{GDBN} does not allow it to take effect | |
1177 | until a time when it is safe. | |
1178 | ||
c906108c SS |
1179 | If you have been using @value{GDBN} to control an attached process or |
1180 | device, you can release it with the @code{detach} command | |
1181 | (@pxref{Attach, ,Debugging an already-running process}). | |
c906108c | 1182 | |
6d2ebf8b | 1183 | @node Shell Commands |
c906108c SS |
1184 | @section Shell commands |
1185 | ||
1186 | If you need to execute occasional shell commands during your | |
1187 | debugging session, there is no need to leave or suspend @value{GDBN}; you can | |
1188 | just use the @code{shell} command. | |
1189 | ||
1190 | @table @code | |
1191 | @kindex shell | |
1192 | @cindex shell escape | |
1193 | @item shell @var{command string} | |
1194 | Invoke a standard shell to execute @var{command string}. | |
c906108c | 1195 | If it exists, the environment variable @code{SHELL} determines which |
d4f3574e SS |
1196 | shell to run. Otherwise @value{GDBN} uses the default shell |
1197 | (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.). | |
c906108c SS |
1198 | @end table |
1199 | ||
1200 | The utility @code{make} is often needed in development environments. | |
1201 | You do not have to use the @code{shell} command for this purpose in | |
1202 | @value{GDBN}: | |
1203 | ||
1204 | @table @code | |
1205 | @kindex make | |
1206 | @cindex calling make | |
1207 | @item make @var{make-args} | |
1208 | Execute the @code{make} program with the specified | |
1209 | arguments. This is equivalent to @samp{shell make @var{make-args}}. | |
1210 | @end table | |
1211 | ||
6d2ebf8b | 1212 | @node Commands |
c906108c SS |
1213 | @chapter @value{GDBN} Commands |
1214 | ||
1215 | You can abbreviate a @value{GDBN} command to the first few letters of the command | |
1216 | name, if that abbreviation is unambiguous; and you can repeat certain | |
1217 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} | |
1218 | key to get @value{GDBN} to fill out the rest of a word in a command (or to | |
1219 | show you the alternatives available, if there is more than one possibility). | |
1220 | ||
1221 | @menu | |
1222 | * Command Syntax:: How to give commands to @value{GDBN} | |
1223 | * Completion:: Command completion | |
1224 | * Help:: How to ask @value{GDBN} for help | |
1225 | @end menu | |
1226 | ||
6d2ebf8b | 1227 | @node Command Syntax |
c906108c SS |
1228 | @section Command syntax |
1229 | ||
1230 | A @value{GDBN} command is a single line of input. There is no limit on | |
1231 | how long it can be. It starts with a command name, which is followed by | |
1232 | arguments whose meaning depends on the command name. For example, the | |
1233 | command @code{step} accepts an argument which is the number of times to | |
1234 | step, as in @samp{step 5}. You can also use the @code{step} command | |
96a2c332 | 1235 | with no arguments. Some commands do not allow any arguments. |
c906108c SS |
1236 | |
1237 | @cindex abbreviation | |
1238 | @value{GDBN} command names may always be truncated if that abbreviation is | |
1239 | unambiguous. Other possible command abbreviations are listed in the | |
1240 | documentation for individual commands. In some cases, even ambiguous | |
1241 | abbreviations are allowed; for example, @code{s} is specially defined as | |
1242 | equivalent to @code{step} even though there are other commands whose | |
1243 | names start with @code{s}. You can test abbreviations by using them as | |
1244 | arguments to the @code{help} command. | |
1245 | ||
1246 | @cindex repeating commands | |
41afff9a | 1247 | @kindex RET @r{(repeat last command)} |
c906108c | 1248 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to |
96a2c332 | 1249 | repeat the previous command. Certain commands (for example, @code{run}) |
c906108c SS |
1250 | will not repeat this way; these are commands whose unintentional |
1251 | repetition might cause trouble and which you are unlikely to want to | |
1252 | repeat. | |
1253 | ||
1254 | The @code{list} and @code{x} commands, when you repeat them with | |
1255 | @key{RET}, construct new arguments rather than repeating | |
1256 | exactly as typed. This permits easy scanning of source or memory. | |
1257 | ||
1258 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy | |
1259 | output, in a way similar to the common utility @code{more} | |
1260 | (@pxref{Screen Size,,Screen size}). Since it is easy to press one | |
1261 | @key{RET} too many in this situation, @value{GDBN} disables command | |
1262 | repetition after any command that generates this sort of display. | |
1263 | ||
41afff9a | 1264 | @kindex # @r{(a comment)} |
c906108c SS |
1265 | @cindex comment |
1266 | Any text from a @kbd{#} to the end of the line is a comment; it does | |
1267 | nothing. This is useful mainly in command files (@pxref{Command | |
1268 | Files,,Command files}). | |
1269 | ||
88118b3a TT |
1270 | @cindex repeating command sequences |
1271 | @kindex C-o @r{(operate-and-get-next)} | |
1272 | The @kbd{C-o} binding is useful for repeating a complex sequence of | |
1273 | commands. This command accepts the current line, like @kbd{RET}, and | |
1274 | then fetches the next line relative to the current line from the history | |
1275 | for editing. | |
1276 | ||
6d2ebf8b | 1277 | @node Completion |
c906108c SS |
1278 | @section Command completion |
1279 | ||
1280 | @cindex completion | |
1281 | @cindex word completion | |
1282 | @value{GDBN} can fill in the rest of a word in a command for you, if there is | |
1283 | only one possibility; it can also show you what the valid possibilities | |
1284 | are for the next word in a command, at any time. This works for @value{GDBN} | |
1285 | commands, @value{GDBN} subcommands, and the names of symbols in your program. | |
1286 | ||
1287 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest | |
1288 | of a word. If there is only one possibility, @value{GDBN} fills in the | |
1289 | word, and waits for you to finish the command (or press @key{RET} to | |
1290 | enter it). For example, if you type | |
1291 | ||
1292 | @c FIXME "@key" does not distinguish its argument sufficiently to permit | |
1293 | @c complete accuracy in these examples; space introduced for clarity. | |
1294 | @c If texinfo enhancements make it unnecessary, it would be nice to | |
1295 | @c replace " @key" by "@key" in the following... | |
474c8240 | 1296 | @smallexample |
c906108c | 1297 | (@value{GDBP}) info bre @key{TAB} |
474c8240 | 1298 | @end smallexample |
c906108c SS |
1299 | |
1300 | @noindent | |
1301 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is | |
1302 | the only @code{info} subcommand beginning with @samp{bre}: | |
1303 | ||
474c8240 | 1304 | @smallexample |
c906108c | 1305 | (@value{GDBP}) info breakpoints |
474c8240 | 1306 | @end smallexample |
c906108c SS |
1307 | |
1308 | @noindent | |
1309 | You can either press @key{RET} at this point, to run the @code{info | |
1310 | breakpoints} command, or backspace and enter something else, if | |
1311 | @samp{breakpoints} does not look like the command you expected. (If you | |
1312 | were sure you wanted @code{info breakpoints} in the first place, you | |
1313 | might as well just type @key{RET} immediately after @samp{info bre}, | |
1314 | to exploit command abbreviations rather than command completion). | |
1315 | ||
1316 | If there is more than one possibility for the next word when you press | |
1317 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more | |
1318 | characters and try again, or just press @key{TAB} a second time; | |
1319 | @value{GDBN} displays all the possible completions for that word. For | |
1320 | example, you might want to set a breakpoint on a subroutine whose name | |
1321 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} | |
1322 | just sounds the bell. Typing @key{TAB} again displays all the | |
1323 | function names in your program that begin with those characters, for | |
1324 | example: | |
1325 | ||
474c8240 | 1326 | @smallexample |
c906108c SS |
1327 | (@value{GDBP}) b make_ @key{TAB} |
1328 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: | |
5d161b24 DB |
1329 | make_a_section_from_file make_environ |
1330 | make_abs_section make_function_type | |
1331 | make_blockvector make_pointer_type | |
1332 | make_cleanup make_reference_type | |
c906108c SS |
1333 | make_command make_symbol_completion_list |
1334 | (@value{GDBP}) b make_ | |
474c8240 | 1335 | @end smallexample |
c906108c SS |
1336 | |
1337 | @noindent | |
1338 | After displaying the available possibilities, @value{GDBN} copies your | |
1339 | partial input (@samp{b make_} in the example) so you can finish the | |
1340 | command. | |
1341 | ||
1342 | If you just want to see the list of alternatives in the first place, you | |
b37052ae | 1343 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} |
7a292a7a | 1344 | means @kbd{@key{META} ?}. You can type this either by holding down a |
c906108c | 1345 | key designated as the @key{META} shift on your keyboard (if there is |
7a292a7a | 1346 | one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}. |
c906108c SS |
1347 | |
1348 | @cindex quotes in commands | |
1349 | @cindex completion of quoted strings | |
1350 | Sometimes the string you need, while logically a ``word'', may contain | |
7a292a7a SS |
1351 | parentheses or other characters that @value{GDBN} normally excludes from |
1352 | its notion of a word. To permit word completion to work in this | |
1353 | situation, you may enclose words in @code{'} (single quote marks) in | |
1354 | @value{GDBN} commands. | |
c906108c | 1355 | |
c906108c | 1356 | The most likely situation where you might need this is in typing the |
b37052ae EZ |
1357 | name of a C@t{++} function. This is because C@t{++} allows function |
1358 | overloading (multiple definitions of the same function, distinguished | |
1359 | by argument type). For example, when you want to set a breakpoint you | |
1360 | may need to distinguish whether you mean the version of @code{name} | |
1361 | that takes an @code{int} parameter, @code{name(int)}, or the version | |
1362 | that takes a @code{float} parameter, @code{name(float)}. To use the | |
1363 | word-completion facilities in this situation, type a single quote | |
1364 | @code{'} at the beginning of the function name. This alerts | |
1365 | @value{GDBN} that it may need to consider more information than usual | |
1366 | when you press @key{TAB} or @kbd{M-?} to request word completion: | |
c906108c | 1367 | |
474c8240 | 1368 | @smallexample |
96a2c332 | 1369 | (@value{GDBP}) b 'bubble( @kbd{M-?} |
c906108c SS |
1370 | bubble(double,double) bubble(int,int) |
1371 | (@value{GDBP}) b 'bubble( | |
474c8240 | 1372 | @end smallexample |
c906108c SS |
1373 | |
1374 | In some cases, @value{GDBN} can tell that completing a name requires using | |
1375 | quotes. When this happens, @value{GDBN} inserts the quote for you (while | |
1376 | completing as much as it can) if you do not type the quote in the first | |
1377 | place: | |
1378 | ||
474c8240 | 1379 | @smallexample |
c906108c SS |
1380 | (@value{GDBP}) b bub @key{TAB} |
1381 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: | |
1382 | (@value{GDBP}) b 'bubble( | |
474c8240 | 1383 | @end smallexample |
c906108c SS |
1384 | |
1385 | @noindent | |
1386 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if | |
1387 | you have not yet started typing the argument list when you ask for | |
1388 | completion on an overloaded symbol. | |
1389 | ||
d4f3574e | 1390 | For more information about overloaded functions, see @ref{C plus plus |
b37052ae | 1391 | expressions, ,C@t{++} expressions}. You can use the command @code{set |
c906108c | 1392 | overload-resolution off} to disable overload resolution; |
b37052ae | 1393 | see @ref{Debugging C plus plus, ,@value{GDBN} features for C@t{++}}. |
c906108c SS |
1394 | |
1395 | ||
6d2ebf8b | 1396 | @node Help |
c906108c SS |
1397 | @section Getting help |
1398 | @cindex online documentation | |
1399 | @kindex help | |
1400 | ||
5d161b24 | 1401 | You can always ask @value{GDBN} itself for information on its commands, |
c906108c SS |
1402 | using the command @code{help}. |
1403 | ||
1404 | @table @code | |
41afff9a | 1405 | @kindex h @r{(@code{help})} |
c906108c SS |
1406 | @item help |
1407 | @itemx h | |
1408 | You can use @code{help} (abbreviated @code{h}) with no arguments to | |
1409 | display a short list of named classes of commands: | |
1410 | ||
1411 | @smallexample | |
1412 | (@value{GDBP}) help | |
1413 | List of classes of commands: | |
1414 | ||
2df3850c | 1415 | aliases -- Aliases of other commands |
c906108c | 1416 | breakpoints -- Making program stop at certain points |
2df3850c | 1417 | data -- Examining data |
c906108c | 1418 | files -- Specifying and examining files |
2df3850c JM |
1419 | internals -- Maintenance commands |
1420 | obscure -- Obscure features | |
1421 | running -- Running the program | |
1422 | stack -- Examining the stack | |
c906108c SS |
1423 | status -- Status inquiries |
1424 | support -- Support facilities | |
96a2c332 SS |
1425 | tracepoints -- Tracing of program execution without@* |
1426 | stopping the program | |
c906108c | 1427 | user-defined -- User-defined commands |
c906108c | 1428 | |
5d161b24 | 1429 | Type "help" followed by a class name for a list of |
c906108c | 1430 | commands in that class. |
5d161b24 | 1431 | Type "help" followed by command name for full |
c906108c SS |
1432 | documentation. |
1433 | Command name abbreviations are allowed if unambiguous. | |
1434 | (@value{GDBP}) | |
1435 | @end smallexample | |
96a2c332 | 1436 | @c the above line break eliminates huge line overfull... |
c906108c SS |
1437 | |
1438 | @item help @var{class} | |
1439 | Using one of the general help classes as an argument, you can get a | |
1440 | list of the individual commands in that class. For example, here is the | |
1441 | help display for the class @code{status}: | |
1442 | ||
1443 | @smallexample | |
1444 | (@value{GDBP}) help status | |
1445 | Status inquiries. | |
1446 | ||
1447 | List of commands: | |
1448 | ||
1449 | @c Line break in "show" line falsifies real output, but needed | |
1450 | @c to fit in smallbook page size. | |
2df3850c JM |
1451 | info -- Generic command for showing things |
1452 | about the program being debugged | |
1453 | show -- Generic command for showing things | |
1454 | about the debugger | |
c906108c | 1455 | |
5d161b24 | 1456 | Type "help" followed by command name for full |
c906108c SS |
1457 | documentation. |
1458 | Command name abbreviations are allowed if unambiguous. | |
1459 | (@value{GDBP}) | |
1460 | @end smallexample | |
1461 | ||
1462 | @item help @var{command} | |
1463 | With a command name as @code{help} argument, @value{GDBN} displays a | |
1464 | short paragraph on how to use that command. | |
1465 | ||
6837a0a2 DB |
1466 | @kindex apropos |
1467 | @item apropos @var{args} | |
1468 | The @code{apropos @var{args}} command searches through all of the @value{GDBN} | |
1469 | commands, and their documentation, for the regular expression specified in | |
1470 | @var{args}. It prints out all matches found. For example: | |
1471 | ||
1472 | @smallexample | |
1473 | apropos reload | |
1474 | @end smallexample | |
1475 | ||
b37052ae EZ |
1476 | @noindent |
1477 | results in: | |
6837a0a2 DB |
1478 | |
1479 | @smallexample | |
6d2ebf8b SS |
1480 | @c @group |
1481 | set symbol-reloading -- Set dynamic symbol table reloading | |
1482 | multiple times in one run | |
1483 | show symbol-reloading -- Show dynamic symbol table reloading | |
1484 | multiple times in one run | |
1485 | @c @end group | |
6837a0a2 DB |
1486 | @end smallexample |
1487 | ||
c906108c SS |
1488 | @kindex complete |
1489 | @item complete @var{args} | |
1490 | The @code{complete @var{args}} command lists all the possible completions | |
1491 | for the beginning of a command. Use @var{args} to specify the beginning of the | |
1492 | command you want completed. For example: | |
1493 | ||
1494 | @smallexample | |
1495 | complete i | |
1496 | @end smallexample | |
1497 | ||
1498 | @noindent results in: | |
1499 | ||
1500 | @smallexample | |
1501 | @group | |
2df3850c JM |
1502 | if |
1503 | ignore | |
c906108c SS |
1504 | info |
1505 | inspect | |
c906108c SS |
1506 | @end group |
1507 | @end smallexample | |
1508 | ||
1509 | @noindent This is intended for use by @sc{gnu} Emacs. | |
1510 | @end table | |
1511 | ||
1512 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} | |
1513 | and @code{show} to inquire about the state of your program, or the state | |
1514 | of @value{GDBN} itself. Each command supports many topics of inquiry; this | |
1515 | manual introduces each of them in the appropriate context. The listings | |
1516 | under @code{info} and under @code{show} in the Index point to | |
1517 | all the sub-commands. @xref{Index}. | |
1518 | ||
1519 | @c @group | |
1520 | @table @code | |
1521 | @kindex info | |
41afff9a | 1522 | @kindex i @r{(@code{info})} |
c906108c SS |
1523 | @item info |
1524 | This command (abbreviated @code{i}) is for describing the state of your | |
1525 | program. For example, you can list the arguments given to your program | |
1526 | with @code{info args}, list the registers currently in use with @code{info | |
1527 | registers}, or list the breakpoints you have set with @code{info breakpoints}. | |
1528 | You can get a complete list of the @code{info} sub-commands with | |
1529 | @w{@code{help info}}. | |
1530 | ||
1531 | @kindex set | |
1532 | @item set | |
5d161b24 | 1533 | You can assign the result of an expression to an environment variable with |
c906108c SS |
1534 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with |
1535 | @code{set prompt $}. | |
1536 | ||
1537 | @kindex show | |
1538 | @item show | |
5d161b24 | 1539 | In contrast to @code{info}, @code{show} is for describing the state of |
c906108c SS |
1540 | @value{GDBN} itself. |
1541 | You can change most of the things you can @code{show}, by using the | |
1542 | related command @code{set}; for example, you can control what number | |
1543 | system is used for displays with @code{set radix}, or simply inquire | |
1544 | which is currently in use with @code{show radix}. | |
1545 | ||
1546 | @kindex info set | |
1547 | To display all the settable parameters and their current | |
1548 | values, you can use @code{show} with no arguments; you may also use | |
1549 | @code{info set}. Both commands produce the same display. | |
1550 | @c FIXME: "info set" violates the rule that "info" is for state of | |
1551 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, | |
1552 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? | |
1553 | @end table | |
1554 | @c @end group | |
1555 | ||
1556 | Here are three miscellaneous @code{show} subcommands, all of which are | |
1557 | exceptional in lacking corresponding @code{set} commands: | |
1558 | ||
1559 | @table @code | |
1560 | @kindex show version | |
1561 | @cindex version number | |
1562 | @item show version | |
1563 | Show what version of @value{GDBN} is running. You should include this | |
2df3850c JM |
1564 | information in @value{GDBN} bug-reports. If multiple versions of |
1565 | @value{GDBN} are in use at your site, you may need to determine which | |
1566 | version of @value{GDBN} you are running; as @value{GDBN} evolves, new | |
1567 | commands are introduced, and old ones may wither away. Also, many | |
1568 | system vendors ship variant versions of @value{GDBN}, and there are | |
96a2c332 | 1569 | variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well. |
2df3850c JM |
1570 | The version number is the same as the one announced when you start |
1571 | @value{GDBN}. | |
c906108c SS |
1572 | |
1573 | @kindex show copying | |
1574 | @item show copying | |
1575 | Display information about permission for copying @value{GDBN}. | |
1576 | ||
1577 | @kindex show warranty | |
1578 | @item show warranty | |
2df3850c | 1579 | Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty, |
96a2c332 | 1580 | if your version of @value{GDBN} comes with one. |
2df3850c | 1581 | |
c906108c SS |
1582 | @end table |
1583 | ||
6d2ebf8b | 1584 | @node Running |
c906108c SS |
1585 | @chapter Running Programs Under @value{GDBN} |
1586 | ||
1587 | When you run a program under @value{GDBN}, you must first generate | |
1588 | debugging information when you compile it. | |
7a292a7a SS |
1589 | |
1590 | You may start @value{GDBN} with its arguments, if any, in an environment | |
1591 | of your choice. If you are doing native debugging, you may redirect | |
1592 | your program's input and output, debug an already running process, or | |
1593 | kill a child process. | |
c906108c SS |
1594 | |
1595 | @menu | |
1596 | * Compilation:: Compiling for debugging | |
1597 | * Starting:: Starting your program | |
c906108c SS |
1598 | * Arguments:: Your program's arguments |
1599 | * Environment:: Your program's environment | |
c906108c SS |
1600 | |
1601 | * Working Directory:: Your program's working directory | |
1602 | * Input/Output:: Your program's input and output | |
1603 | * Attach:: Debugging an already-running process | |
1604 | * Kill Process:: Killing the child process | |
c906108c SS |
1605 | |
1606 | * Threads:: Debugging programs with multiple threads | |
1607 | * Processes:: Debugging programs with multiple processes | |
1608 | @end menu | |
1609 | ||
6d2ebf8b | 1610 | @node Compilation |
c906108c SS |
1611 | @section Compiling for debugging |
1612 | ||
1613 | In order to debug a program effectively, you need to generate | |
1614 | debugging information when you compile it. This debugging information | |
1615 | is stored in the object file; it describes the data type of each | |
1616 | variable or function and the correspondence between source line numbers | |
1617 | and addresses in the executable code. | |
1618 | ||
1619 | To request debugging information, specify the @samp{-g} option when you run | |
1620 | the compiler. | |
1621 | ||
e2e0bcd1 JB |
1622 | Most compilers do not include information about preprocessor macros in |
1623 | the debugging information if you specify the @option{-g} flag alone, | |
1624 | because this information is rather large. Version 3.1 of @value{NGCC}, | |
1625 | the @sc{gnu} C compiler, provides macro information if you specify the | |
1626 | options @option{-gdwarf-2} and @option{-g3}; the former option requests | |
1627 | debugging information in the Dwarf 2 format, and the latter requests | |
1628 | ``extra information''. In the future, we hope to find more compact ways | |
1629 | to represent macro information, so that it can be included with | |
1630 | @option{-g} alone. | |
1631 | ||
c906108c SS |
1632 | Many C compilers are unable to handle the @samp{-g} and @samp{-O} |
1633 | options together. Using those compilers, you cannot generate optimized | |
1634 | executables containing debugging information. | |
1635 | ||
53a5351d JM |
1636 | @value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or |
1637 | without @samp{-O}, making it possible to debug optimized code. We | |
1638 | recommend that you @emph{always} use @samp{-g} whenever you compile a | |
1639 | program. You may think your program is correct, but there is no sense | |
1640 | in pushing your luck. | |
c906108c SS |
1641 | |
1642 | @cindex optimized code, debugging | |
1643 | @cindex debugging optimized code | |
1644 | When you debug a program compiled with @samp{-g -O}, remember that the | |
1645 | optimizer is rearranging your code; the debugger shows you what is | |
1646 | really there. Do not be too surprised when the execution path does not | |
1647 | exactly match your source file! An extreme example: if you define a | |
1648 | variable, but never use it, @value{GDBN} never sees that | |
1649 | variable---because the compiler optimizes it out of existence. | |
1650 | ||
1651 | Some things do not work as well with @samp{-g -O} as with just | |
1652 | @samp{-g}, particularly on machines with instruction scheduling. If in | |
1653 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, | |
1654 | please report it to us as a bug (including a test case!). | |
1655 | ||
1656 | Older versions of the @sc{gnu} C compiler permitted a variant option | |
1657 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this | |
1658 | format; if your @sc{gnu} C compiler has this option, do not use it. | |
1659 | ||
1660 | @need 2000 | |
6d2ebf8b | 1661 | @node Starting |
c906108c SS |
1662 | @section Starting your program |
1663 | @cindex starting | |
1664 | @cindex running | |
1665 | ||
1666 | @table @code | |
1667 | @kindex run | |
41afff9a | 1668 | @kindex r @r{(@code{run})} |
c906108c SS |
1669 | @item run |
1670 | @itemx r | |
7a292a7a SS |
1671 | Use the @code{run} command to start your program under @value{GDBN}. |
1672 | You must first specify the program name (except on VxWorks) with an | |
1673 | argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of | |
1674 | @value{GDBN}}), or by using the @code{file} or @code{exec-file} command | |
1675 | (@pxref{Files, ,Commands to specify files}). | |
c906108c SS |
1676 | |
1677 | @end table | |
1678 | ||
c906108c SS |
1679 | If you are running your program in an execution environment that |
1680 | supports processes, @code{run} creates an inferior process and makes | |
1681 | that process run your program. (In environments without processes, | |
1682 | @code{run} jumps to the start of your program.) | |
1683 | ||
1684 | The execution of a program is affected by certain information it | |
1685 | receives from its superior. @value{GDBN} provides ways to specify this | |
1686 | information, which you must do @emph{before} starting your program. (You | |
1687 | can change it after starting your program, but such changes only affect | |
1688 | your program the next time you start it.) This information may be | |
1689 | divided into four categories: | |
1690 | ||
1691 | @table @asis | |
1692 | @item The @emph{arguments.} | |
1693 | Specify the arguments to give your program as the arguments of the | |
1694 | @code{run} command. If a shell is available on your target, the shell | |
1695 | is used to pass the arguments, so that you may use normal conventions | |
1696 | (such as wildcard expansion or variable substitution) in describing | |
1697 | the arguments. | |
1698 | In Unix systems, you can control which shell is used with the | |
1699 | @code{SHELL} environment variable. | |
1700 | @xref{Arguments, ,Your program's arguments}. | |
1701 | ||
1702 | @item The @emph{environment.} | |
1703 | Your program normally inherits its environment from @value{GDBN}, but you can | |
1704 | use the @value{GDBN} commands @code{set environment} and @code{unset | |
1705 | environment} to change parts of the environment that affect | |
1706 | your program. @xref{Environment, ,Your program's environment}. | |
1707 | ||
1708 | @item The @emph{working directory.} | |
1709 | Your program inherits its working directory from @value{GDBN}. You can set | |
1710 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. | |
1711 | @xref{Working Directory, ,Your program's working directory}. | |
1712 | ||
1713 | @item The @emph{standard input and output.} | |
1714 | Your program normally uses the same device for standard input and | |
1715 | standard output as @value{GDBN} is using. You can redirect input and output | |
1716 | in the @code{run} command line, or you can use the @code{tty} command to | |
1717 | set a different device for your program. | |
1718 | @xref{Input/Output, ,Your program's input and output}. | |
1719 | ||
1720 | @cindex pipes | |
1721 | @emph{Warning:} While input and output redirection work, you cannot use | |
1722 | pipes to pass the output of the program you are debugging to another | |
1723 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the | |
1724 | wrong program. | |
1725 | @end table | |
c906108c SS |
1726 | |
1727 | When you issue the @code{run} command, your program begins to execute | |
1728 | immediately. @xref{Stopping, ,Stopping and continuing}, for discussion | |
1729 | of how to arrange for your program to stop. Once your program has | |
1730 | stopped, you may call functions in your program, using the @code{print} | |
1731 | or @code{call} commands. @xref{Data, ,Examining Data}. | |
1732 | ||
1733 | If the modification time of your symbol file has changed since the last | |
1734 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol | |
1735 | table, and reads it again. When it does this, @value{GDBN} tries to retain | |
1736 | your current breakpoints. | |
1737 | ||
6d2ebf8b | 1738 | @node Arguments |
c906108c SS |
1739 | @section Your program's arguments |
1740 | ||
1741 | @cindex arguments (to your program) | |
1742 | The arguments to your program can be specified by the arguments of the | |
5d161b24 | 1743 | @code{run} command. |
c906108c SS |
1744 | They are passed to a shell, which expands wildcard characters and |
1745 | performs redirection of I/O, and thence to your program. Your | |
1746 | @code{SHELL} environment variable (if it exists) specifies what shell | |
1747 | @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses | |
d4f3574e SS |
1748 | the default shell (@file{/bin/sh} on Unix). |
1749 | ||
1750 | On non-Unix systems, the program is usually invoked directly by | |
1751 | @value{GDBN}, which emulates I/O redirection via the appropriate system | |
1752 | calls, and the wildcard characters are expanded by the startup code of | |
1753 | the program, not by the shell. | |
c906108c SS |
1754 | |
1755 | @code{run} with no arguments uses the same arguments used by the previous | |
1756 | @code{run}, or those set by the @code{set args} command. | |
1757 | ||
c906108c | 1758 | @table @code |
41afff9a | 1759 | @kindex set args |
c906108c SS |
1760 | @item set args |
1761 | Specify the arguments to be used the next time your program is run. If | |
1762 | @code{set args} has no arguments, @code{run} executes your program | |
1763 | with no arguments. Once you have run your program with arguments, | |
1764 | using @code{set args} before the next @code{run} is the only way to run | |
1765 | it again without arguments. | |
1766 | ||
1767 | @kindex show args | |
1768 | @item show args | |
1769 | Show the arguments to give your program when it is started. | |
1770 | @end table | |
1771 | ||
6d2ebf8b | 1772 | @node Environment |
c906108c SS |
1773 | @section Your program's environment |
1774 | ||
1775 | @cindex environment (of your program) | |
1776 | The @dfn{environment} consists of a set of environment variables and | |
1777 | their values. Environment variables conventionally record such things as | |
1778 | your user name, your home directory, your terminal type, and your search | |
1779 | path for programs to run. Usually you set up environment variables with | |
1780 | the shell and they are inherited by all the other programs you run. When | |
1781 | debugging, it can be useful to try running your program with a modified | |
1782 | environment without having to start @value{GDBN} over again. | |
1783 | ||
1784 | @table @code | |
1785 | @kindex path | |
1786 | @item path @var{directory} | |
1787 | Add @var{directory} to the front of the @code{PATH} environment variable | |
17cc6a06 EZ |
1788 | (the search path for executables) that will be passed to your program. |
1789 | The value of @code{PATH} used by @value{GDBN} does not change. | |
d4f3574e SS |
1790 | You may specify several directory names, separated by whitespace or by a |
1791 | system-dependent separator character (@samp{:} on Unix, @samp{;} on | |
1792 | MS-DOS and MS-Windows). If @var{directory} is already in the path, it | |
1793 | is moved to the front, so it is searched sooner. | |
c906108c SS |
1794 | |
1795 | You can use the string @samp{$cwd} to refer to whatever is the current | |
1796 | working directory at the time @value{GDBN} searches the path. If you | |
1797 | use @samp{.} instead, it refers to the directory where you executed the | |
1798 | @code{path} command. @value{GDBN} replaces @samp{.} in the | |
1799 | @var{directory} argument (with the current path) before adding | |
1800 | @var{directory} to the search path. | |
1801 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to | |
1802 | @c document that, since repeating it would be a no-op. | |
1803 | ||
1804 | @kindex show paths | |
1805 | @item show paths | |
1806 | Display the list of search paths for executables (the @code{PATH} | |
1807 | environment variable). | |
1808 | ||
1809 | @kindex show environment | |
1810 | @item show environment @r{[}@var{varname}@r{]} | |
1811 | Print the value of environment variable @var{varname} to be given to | |
1812 | your program when it starts. If you do not supply @var{varname}, | |
1813 | print the names and values of all environment variables to be given to | |
1814 | your program. You can abbreviate @code{environment} as @code{env}. | |
1815 | ||
1816 | @kindex set environment | |
53a5351d | 1817 | @item set environment @var{varname} @r{[}=@var{value}@r{]} |
c906108c SS |
1818 | Set environment variable @var{varname} to @var{value}. The value |
1819 | changes for your program only, not for @value{GDBN} itself. @var{value} may | |
1820 | be any string; the values of environment variables are just strings, and | |
1821 | any interpretation is supplied by your program itself. The @var{value} | |
1822 | parameter is optional; if it is eliminated, the variable is set to a | |
1823 | null value. | |
1824 | @c "any string" here does not include leading, trailing | |
1825 | @c blanks. Gnu asks: does anyone care? | |
1826 | ||
1827 | For example, this command: | |
1828 | ||
474c8240 | 1829 | @smallexample |
c906108c | 1830 | set env USER = foo |
474c8240 | 1831 | @end smallexample |
c906108c SS |
1832 | |
1833 | @noindent | |
d4f3574e | 1834 | tells the debugged program, when subsequently run, that its user is named |
c906108c SS |
1835 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they |
1836 | are not actually required.) | |
1837 | ||
1838 | @kindex unset environment | |
1839 | @item unset environment @var{varname} | |
1840 | Remove variable @var{varname} from the environment to be passed to your | |
1841 | program. This is different from @samp{set env @var{varname} =}; | |
1842 | @code{unset environment} removes the variable from the environment, | |
1843 | rather than assigning it an empty value. | |
1844 | @end table | |
1845 | ||
d4f3574e SS |
1846 | @emph{Warning:} On Unix systems, @value{GDBN} runs your program using |
1847 | the shell indicated | |
c906108c SS |
1848 | by your @code{SHELL} environment variable if it exists (or |
1849 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell | |
1850 | that runs an initialization file---such as @file{.cshrc} for C-shell, or | |
1851 | @file{.bashrc} for BASH---any variables you set in that file affect | |
1852 | your program. You may wish to move setting of environment variables to | |
1853 | files that are only run when you sign on, such as @file{.login} or | |
1854 | @file{.profile}. | |
1855 | ||
6d2ebf8b | 1856 | @node Working Directory |
c906108c SS |
1857 | @section Your program's working directory |
1858 | ||
1859 | @cindex working directory (of your program) | |
1860 | Each time you start your program with @code{run}, it inherits its | |
1861 | working directory from the current working directory of @value{GDBN}. | |
1862 | The @value{GDBN} working directory is initially whatever it inherited | |
1863 | from its parent process (typically the shell), but you can specify a new | |
1864 | working directory in @value{GDBN} with the @code{cd} command. | |
1865 | ||
1866 | The @value{GDBN} working directory also serves as a default for the commands | |
1867 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to | |
1868 | specify files}. | |
1869 | ||
1870 | @table @code | |
1871 | @kindex cd | |
1872 | @item cd @var{directory} | |
1873 | Set the @value{GDBN} working directory to @var{directory}. | |
1874 | ||
1875 | @kindex pwd | |
1876 | @item pwd | |
1877 | Print the @value{GDBN} working directory. | |
1878 | @end table | |
1879 | ||
6d2ebf8b | 1880 | @node Input/Output |
c906108c SS |
1881 | @section Your program's input and output |
1882 | ||
1883 | @cindex redirection | |
1884 | @cindex i/o | |
1885 | @cindex terminal | |
1886 | By default, the program you run under @value{GDBN} does input and output to | |
5d161b24 | 1887 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal |
c906108c SS |
1888 | to its own terminal modes to interact with you, but it records the terminal |
1889 | modes your program was using and switches back to them when you continue | |
1890 | running your program. | |
1891 | ||
1892 | @table @code | |
1893 | @kindex info terminal | |
1894 | @item info terminal | |
1895 | Displays information recorded by @value{GDBN} about the terminal modes your | |
1896 | program is using. | |
1897 | @end table | |
1898 | ||
1899 | You can redirect your program's input and/or output using shell | |
1900 | redirection with the @code{run} command. For example, | |
1901 | ||
474c8240 | 1902 | @smallexample |
c906108c | 1903 | run > outfile |
474c8240 | 1904 | @end smallexample |
c906108c SS |
1905 | |
1906 | @noindent | |
1907 | starts your program, diverting its output to the file @file{outfile}. | |
1908 | ||
1909 | @kindex tty | |
1910 | @cindex controlling terminal | |
1911 | Another way to specify where your program should do input and output is | |
1912 | with the @code{tty} command. This command accepts a file name as | |
1913 | argument, and causes this file to be the default for future @code{run} | |
1914 | commands. It also resets the controlling terminal for the child | |
1915 | process, for future @code{run} commands. For example, | |
1916 | ||
474c8240 | 1917 | @smallexample |
c906108c | 1918 | tty /dev/ttyb |
474c8240 | 1919 | @end smallexample |
c906108c SS |
1920 | |
1921 | @noindent | |
1922 | directs that processes started with subsequent @code{run} commands | |
1923 | default to do input and output on the terminal @file{/dev/ttyb} and have | |
1924 | that as their controlling terminal. | |
1925 | ||
1926 | An explicit redirection in @code{run} overrides the @code{tty} command's | |
1927 | effect on the input/output device, but not its effect on the controlling | |
1928 | terminal. | |
1929 | ||
1930 | When you use the @code{tty} command or redirect input in the @code{run} | |
1931 | command, only the input @emph{for your program} is affected. The input | |
1932 | for @value{GDBN} still comes from your terminal. | |
1933 | ||
6d2ebf8b | 1934 | @node Attach |
c906108c SS |
1935 | @section Debugging an already-running process |
1936 | @kindex attach | |
1937 | @cindex attach | |
1938 | ||
1939 | @table @code | |
1940 | @item attach @var{process-id} | |
1941 | This command attaches to a running process---one that was started | |
1942 | outside @value{GDBN}. (@code{info files} shows your active | |
1943 | targets.) The command takes as argument a process ID. The usual way to | |
1944 | find out the process-id of a Unix process is with the @code{ps} utility, | |
1945 | or with the @samp{jobs -l} shell command. | |
1946 | ||
1947 | @code{attach} does not repeat if you press @key{RET} a second time after | |
1948 | executing the command. | |
1949 | @end table | |
1950 | ||
1951 | To use @code{attach}, your program must be running in an environment | |
1952 | which supports processes; for example, @code{attach} does not work for | |
1953 | programs on bare-board targets that lack an operating system. You must | |
1954 | also have permission to send the process a signal. | |
1955 | ||
1956 | When you use @code{attach}, the debugger finds the program running in | |
1957 | the process first by looking in the current working directory, then (if | |
1958 | the program is not found) by using the source file search path | |
1959 | (@pxref{Source Path, ,Specifying source directories}). You can also use | |
1960 | the @code{file} command to load the program. @xref{Files, ,Commands to | |
1961 | Specify Files}. | |
1962 | ||
1963 | The first thing @value{GDBN} does after arranging to debug the specified | |
1964 | process is to stop it. You can examine and modify an attached process | |
53a5351d JM |
1965 | with all the @value{GDBN} commands that are ordinarily available when |
1966 | you start processes with @code{run}. You can insert breakpoints; you | |
1967 | can step and continue; you can modify storage. If you would rather the | |
1968 | process continue running, you may use the @code{continue} command after | |
c906108c SS |
1969 | attaching @value{GDBN} to the process. |
1970 | ||
1971 | @table @code | |
1972 | @kindex detach | |
1973 | @item detach | |
1974 | When you have finished debugging the attached process, you can use the | |
1975 | @code{detach} command to release it from @value{GDBN} control. Detaching | |
1976 | the process continues its execution. After the @code{detach} command, | |
1977 | that process and @value{GDBN} become completely independent once more, and you | |
1978 | are ready to @code{attach} another process or start one with @code{run}. | |
1979 | @code{detach} does not repeat if you press @key{RET} again after | |
1980 | executing the command. | |
1981 | @end table | |
1982 | ||
1983 | If you exit @value{GDBN} or use the @code{run} command while you have an | |
1984 | attached process, you kill that process. By default, @value{GDBN} asks | |
1985 | for confirmation if you try to do either of these things; you can | |
1986 | control whether or not you need to confirm by using the @code{set | |
1987 | confirm} command (@pxref{Messages/Warnings, ,Optional warnings and | |
1988 | messages}). | |
1989 | ||
6d2ebf8b | 1990 | @node Kill Process |
c906108c | 1991 | @section Killing the child process |
c906108c SS |
1992 | |
1993 | @table @code | |
1994 | @kindex kill | |
1995 | @item kill | |
1996 | Kill the child process in which your program is running under @value{GDBN}. | |
1997 | @end table | |
1998 | ||
1999 | This command is useful if you wish to debug a core dump instead of a | |
2000 | running process. @value{GDBN} ignores any core dump file while your program | |
2001 | is running. | |
2002 | ||
2003 | On some operating systems, a program cannot be executed outside @value{GDBN} | |
2004 | while you have breakpoints set on it inside @value{GDBN}. You can use the | |
2005 | @code{kill} command in this situation to permit running your program | |
2006 | outside the debugger. | |
2007 | ||
2008 | The @code{kill} command is also useful if you wish to recompile and | |
2009 | relink your program, since on many systems it is impossible to modify an | |
2010 | executable file while it is running in a process. In this case, when you | |
2011 | next type @code{run}, @value{GDBN} notices that the file has changed, and | |
2012 | reads the symbol table again (while trying to preserve your current | |
2013 | breakpoint settings). | |
2014 | ||
6d2ebf8b | 2015 | @node Threads |
c906108c | 2016 | @section Debugging programs with multiple threads |
c906108c SS |
2017 | |
2018 | @cindex threads of execution | |
2019 | @cindex multiple threads | |
2020 | @cindex switching threads | |
2021 | In some operating systems, such as HP-UX and Solaris, a single program | |
2022 | may have more than one @dfn{thread} of execution. The precise semantics | |
2023 | of threads differ from one operating system to another, but in general | |
2024 | the threads of a single program are akin to multiple processes---except | |
2025 | that they share one address space (that is, they can all examine and | |
2026 | modify the same variables). On the other hand, each thread has its own | |
2027 | registers and execution stack, and perhaps private memory. | |
2028 | ||
2029 | @value{GDBN} provides these facilities for debugging multi-thread | |
2030 | programs: | |
2031 | ||
2032 | @itemize @bullet | |
2033 | @item automatic notification of new threads | |
2034 | @item @samp{thread @var{threadno}}, a command to switch among threads | |
2035 | @item @samp{info threads}, a command to inquire about existing threads | |
5d161b24 | 2036 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, |
c906108c SS |
2037 | a command to apply a command to a list of threads |
2038 | @item thread-specific breakpoints | |
2039 | @end itemize | |
2040 | ||
c906108c SS |
2041 | @quotation |
2042 | @emph{Warning:} These facilities are not yet available on every | |
2043 | @value{GDBN} configuration where the operating system supports threads. | |
2044 | If your @value{GDBN} does not support threads, these commands have no | |
2045 | effect. For example, a system without thread support shows no output | |
2046 | from @samp{info threads}, and always rejects the @code{thread} command, | |
2047 | like this: | |
2048 | ||
2049 | @smallexample | |
2050 | (@value{GDBP}) info threads | |
2051 | (@value{GDBP}) thread 1 | |
2052 | Thread ID 1 not known. Use the "info threads" command to | |
2053 | see the IDs of currently known threads. | |
2054 | @end smallexample | |
2055 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB | |
2056 | @c doesn't support threads"? | |
2057 | @end quotation | |
c906108c SS |
2058 | |
2059 | @cindex focus of debugging | |
2060 | @cindex current thread | |
2061 | The @value{GDBN} thread debugging facility allows you to observe all | |
2062 | threads while your program runs---but whenever @value{GDBN} takes | |
2063 | control, one thread in particular is always the focus of debugging. | |
2064 | This thread is called the @dfn{current thread}. Debugging commands show | |
2065 | program information from the perspective of the current thread. | |
2066 | ||
41afff9a | 2067 | @cindex @code{New} @var{systag} message |
c906108c SS |
2068 | @cindex thread identifier (system) |
2069 | @c FIXME-implementors!! It would be more helpful if the [New...] message | |
2070 | @c included GDB's numeric thread handle, so you could just go to that | |
2071 | @c thread without first checking `info threads'. | |
2072 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
2073 | the target system's identification for the thread with a message in the | |
2074 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
2075 | whose form varies depending on the particular system. For example, on | |
2076 | LynxOS, you might see | |
2077 | ||
474c8240 | 2078 | @smallexample |
c906108c | 2079 | [New process 35 thread 27] |
474c8240 | 2080 | @end smallexample |
c906108c SS |
2081 | |
2082 | @noindent | |
2083 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, | |
2084 | the @var{systag} is simply something like @samp{process 368}, with no | |
2085 | further qualifier. | |
2086 | ||
2087 | @c FIXME!! (1) Does the [New...] message appear even for the very first | |
2088 | @c thread of a program, or does it only appear for the | |
6ca652b0 | 2089 | @c second---i.e.@: when it becomes obvious we have a multithread |
c906108c SS |
2090 | @c program? |
2091 | @c (2) *Is* there necessarily a first thread always? Or do some | |
2092 | @c multithread systems permit starting a program with multiple | |
5d161b24 | 2093 | @c threads ab initio? |
c906108c SS |
2094 | |
2095 | @cindex thread number | |
2096 | @cindex thread identifier (GDB) | |
2097 | For debugging purposes, @value{GDBN} associates its own thread | |
2098 | number---always a single integer---with each thread in your program. | |
2099 | ||
2100 | @table @code | |
2101 | @kindex info threads | |
2102 | @item info threads | |
2103 | Display a summary of all threads currently in your | |
2104 | program. @value{GDBN} displays for each thread (in this order): | |
2105 | ||
2106 | @enumerate | |
2107 | @item the thread number assigned by @value{GDBN} | |
2108 | ||
2109 | @item the target system's thread identifier (@var{systag}) | |
2110 | ||
2111 | @item the current stack frame summary for that thread | |
2112 | @end enumerate | |
2113 | ||
2114 | @noindent | |
2115 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
2116 | indicates the current thread. | |
2117 | ||
5d161b24 | 2118 | For example, |
c906108c SS |
2119 | @end table |
2120 | @c end table here to get a little more width for example | |
2121 | ||
2122 | @smallexample | |
2123 | (@value{GDBP}) info threads | |
2124 | 3 process 35 thread 27 0x34e5 in sigpause () | |
2125 | 2 process 35 thread 23 0x34e5 in sigpause () | |
2126 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) | |
2127 | at threadtest.c:68 | |
2128 | @end smallexample | |
53a5351d JM |
2129 | |
2130 | On HP-UX systems: | |
c906108c SS |
2131 | |
2132 | @cindex thread number | |
2133 | @cindex thread identifier (GDB) | |
2134 | For debugging purposes, @value{GDBN} associates its own thread | |
2135 | number---a small integer assigned in thread-creation order---with each | |
2136 | thread in your program. | |
2137 | ||
41afff9a EZ |
2138 | @cindex @code{New} @var{systag} message, on HP-UX |
2139 | @cindex thread identifier (system), on HP-UX | |
c906108c SS |
2140 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
2141 | @c included GDB's numeric thread handle, so you could just go to that | |
2142 | @c thread without first checking `info threads'. | |
2143 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
2144 | both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the | |
2145 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
2146 | whose form varies depending on the particular system. For example, on | |
2147 | HP-UX, you see | |
2148 | ||
474c8240 | 2149 | @smallexample |
c906108c | 2150 | [New thread 2 (system thread 26594)] |
474c8240 | 2151 | @end smallexample |
c906108c SS |
2152 | |
2153 | @noindent | |
5d161b24 | 2154 | when @value{GDBN} notices a new thread. |
c906108c SS |
2155 | |
2156 | @table @code | |
2157 | @kindex info threads | |
2158 | @item info threads | |
2159 | Display a summary of all threads currently in your | |
2160 | program. @value{GDBN} displays for each thread (in this order): | |
2161 | ||
2162 | @enumerate | |
2163 | @item the thread number assigned by @value{GDBN} | |
2164 | ||
2165 | @item the target system's thread identifier (@var{systag}) | |
2166 | ||
2167 | @item the current stack frame summary for that thread | |
2168 | @end enumerate | |
2169 | ||
2170 | @noindent | |
2171 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
2172 | indicates the current thread. | |
2173 | ||
5d161b24 | 2174 | For example, |
c906108c SS |
2175 | @end table |
2176 | @c end table here to get a little more width for example | |
2177 | ||
474c8240 | 2178 | @smallexample |
c906108c | 2179 | (@value{GDBP}) info threads |
6d2ebf8b SS |
2180 | * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") \@* |
2181 | at quicksort.c:137 | |
2182 | 2 system thread 26606 0x7b0030d8 in __ksleep () \@* | |
2183 | from /usr/lib/libc.2 | |
2184 | 1 system thread 27905 0x7b003498 in _brk () \@* | |
2185 | from /usr/lib/libc.2 | |
474c8240 | 2186 | @end smallexample |
c906108c SS |
2187 | |
2188 | @table @code | |
2189 | @kindex thread @var{threadno} | |
2190 | @item thread @var{threadno} | |
2191 | Make thread number @var{threadno} the current thread. The command | |
2192 | argument @var{threadno} is the internal @value{GDBN} thread number, as | |
2193 | shown in the first field of the @samp{info threads} display. | |
2194 | @value{GDBN} responds by displaying the system identifier of the thread | |
2195 | you selected, and its current stack frame summary: | |
2196 | ||
2197 | @smallexample | |
2198 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one | |
2199 | (@value{GDBP}) thread 2 | |
c906108c | 2200 | [Switching to process 35 thread 23] |
c906108c SS |
2201 | 0x34e5 in sigpause () |
2202 | @end smallexample | |
2203 | ||
2204 | @noindent | |
2205 | As with the @samp{[New @dots{}]} message, the form of the text after | |
2206 | @samp{Switching to} depends on your system's conventions for identifying | |
5d161b24 | 2207 | threads. |
c906108c SS |
2208 | |
2209 | @kindex thread apply | |
2210 | @item thread apply [@var{threadno}] [@var{all}] @var{args} | |
2211 | The @code{thread apply} command allows you to apply a command to one or | |
2212 | more threads. Specify the numbers of the threads that you want affected | |
2213 | with the command argument @var{threadno}. @var{threadno} is the internal | |
2214 | @value{GDBN} thread number, as shown in the first field of the @samp{info | |
5d161b24 DB |
2215 | threads} display. To apply a command to all threads, use |
2216 | @code{thread apply all} @var{args}. | |
c906108c SS |
2217 | @end table |
2218 | ||
2219 | @cindex automatic thread selection | |
2220 | @cindex switching threads automatically | |
2221 | @cindex threads, automatic switching | |
2222 | Whenever @value{GDBN} stops your program, due to a breakpoint or a | |
2223 | signal, it automatically selects the thread where that breakpoint or | |
2224 | signal happened. @value{GDBN} alerts you to the context switch with a | |
2225 | message of the form @samp{[Switching to @var{systag}]} to identify the | |
2226 | thread. | |
2227 | ||
2228 | @xref{Thread Stops,,Stopping and starting multi-thread programs}, for | |
2229 | more information about how @value{GDBN} behaves when you stop and start | |
2230 | programs with multiple threads. | |
2231 | ||
2232 | @xref{Set Watchpoints,,Setting watchpoints}, for information about | |
2233 | watchpoints in programs with multiple threads. | |
c906108c | 2234 | |
6d2ebf8b | 2235 | @node Processes |
c906108c SS |
2236 | @section Debugging programs with multiple processes |
2237 | ||
2238 | @cindex fork, debugging programs which call | |
2239 | @cindex multiple processes | |
2240 | @cindex processes, multiple | |
53a5351d JM |
2241 | On most systems, @value{GDBN} has no special support for debugging |
2242 | programs which create additional processes using the @code{fork} | |
2243 | function. When a program forks, @value{GDBN} will continue to debug the | |
2244 | parent process and the child process will run unimpeded. If you have | |
2245 | set a breakpoint in any code which the child then executes, the child | |
2246 | will get a @code{SIGTRAP} signal which (unless it catches the signal) | |
2247 | will cause it to terminate. | |
c906108c SS |
2248 | |
2249 | However, if you want to debug the child process there is a workaround | |
2250 | which isn't too painful. Put a call to @code{sleep} in the code which | |
2251 | the child process executes after the fork. It may be useful to sleep | |
2252 | only if a certain environment variable is set, or a certain file exists, | |
2253 | so that the delay need not occur when you don't want to run @value{GDBN} | |
2254 | on the child. While the child is sleeping, use the @code{ps} program to | |
2255 | get its process ID. Then tell @value{GDBN} (a new invocation of | |
2256 | @value{GDBN} if you are also debugging the parent process) to attach to | |
d4f3574e | 2257 | the child process (@pxref{Attach}). From that point on you can debug |
c906108c | 2258 | the child process just like any other process which you attached to. |
c906108c | 2259 | |
53a5351d JM |
2260 | On HP-UX (11.x and later only?), @value{GDBN} provides support for |
2261 | debugging programs that create additional processes using the | |
2262 | @code{fork} or @code{vfork} function. | |
c906108c SS |
2263 | |
2264 | By default, when a program forks, @value{GDBN} will continue to debug | |
2265 | the parent process and the child process will run unimpeded. | |
2266 | ||
2267 | If you want to follow the child process instead of the parent process, | |
2268 | use the command @w{@code{set follow-fork-mode}}. | |
2269 | ||
2270 | @table @code | |
2271 | @kindex set follow-fork-mode | |
2272 | @item set follow-fork-mode @var{mode} | |
2273 | Set the debugger response to a program call of @code{fork} or | |
2274 | @code{vfork}. A call to @code{fork} or @code{vfork} creates a new | |
2275 | process. The @var{mode} can be: | |
2276 | ||
2277 | @table @code | |
2278 | @item parent | |
2279 | The original process is debugged after a fork. The child process runs | |
2df3850c | 2280 | unimpeded. This is the default. |
c906108c SS |
2281 | |
2282 | @item child | |
2283 | The new process is debugged after a fork. The parent process runs | |
2284 | unimpeded. | |
2285 | ||
2286 | @item ask | |
2287 | The debugger will ask for one of the above choices. | |
2288 | @end table | |
2289 | ||
2290 | @item show follow-fork-mode | |
2df3850c | 2291 | Display the current debugger response to a @code{fork} or @code{vfork} call. |
c906108c SS |
2292 | @end table |
2293 | ||
2294 | If you ask to debug a child process and a @code{vfork} is followed by an | |
2295 | @code{exec}, @value{GDBN} executes the new target up to the first | |
2296 | breakpoint in the new target. If you have a breakpoint set on | |
2297 | @code{main} in your original program, the breakpoint will also be set on | |
2298 | the child process's @code{main}. | |
2299 | ||
2300 | When a child process is spawned by @code{vfork}, you cannot debug the | |
2301 | child or parent until an @code{exec} call completes. | |
2302 | ||
2303 | If you issue a @code{run} command to @value{GDBN} after an @code{exec} | |
2304 | call executes, the new target restarts. To restart the parent process, | |
2305 | use the @code{file} command with the parent executable name as its | |
2306 | argument. | |
2307 | ||
2308 | You can use the @code{catch} command to make @value{GDBN} stop whenever | |
2309 | a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set | |
2310 | Catchpoints, ,Setting catchpoints}. | |
c906108c | 2311 | |
6d2ebf8b | 2312 | @node Stopping |
c906108c SS |
2313 | @chapter Stopping and Continuing |
2314 | ||
2315 | The principal purposes of using a debugger are so that you can stop your | |
2316 | program before it terminates; or so that, if your program runs into | |
2317 | trouble, you can investigate and find out why. | |
2318 | ||
7a292a7a SS |
2319 | Inside @value{GDBN}, your program may stop for any of several reasons, |
2320 | such as a signal, a breakpoint, or reaching a new line after a | |
2321 | @value{GDBN} command such as @code{step}. You may then examine and | |
2322 | change variables, set new breakpoints or remove old ones, and then | |
2323 | continue execution. Usually, the messages shown by @value{GDBN} provide | |
2324 | ample explanation of the status of your program---but you can also | |
2325 | explicitly request this information at any time. | |
c906108c SS |
2326 | |
2327 | @table @code | |
2328 | @kindex info program | |
2329 | @item info program | |
2330 | Display information about the status of your program: whether it is | |
7a292a7a | 2331 | running or not, what process it is, and why it stopped. |
c906108c SS |
2332 | @end table |
2333 | ||
2334 | @menu | |
2335 | * Breakpoints:: Breakpoints, watchpoints, and catchpoints | |
2336 | * Continuing and Stepping:: Resuming execution | |
c906108c | 2337 | * Signals:: Signals |
c906108c | 2338 | * Thread Stops:: Stopping and starting multi-thread programs |
c906108c SS |
2339 | @end menu |
2340 | ||
6d2ebf8b | 2341 | @node Breakpoints |
c906108c SS |
2342 | @section Breakpoints, watchpoints, and catchpoints |
2343 | ||
2344 | @cindex breakpoints | |
2345 | A @dfn{breakpoint} makes your program stop whenever a certain point in | |
2346 | the program is reached. For each breakpoint, you can add conditions to | |
2347 | control in finer detail whether your program stops. You can set | |
2348 | breakpoints with the @code{break} command and its variants (@pxref{Set | |
2349 | Breaks, ,Setting breakpoints}), to specify the place where your program | |
2350 | should stop by line number, function name or exact address in the | |
2351 | program. | |
2352 | ||
2353 | In HP-UX, SunOS 4.x, SVR4, and Alpha OSF/1 configurations, you can set | |
2354 | breakpoints in shared libraries before the executable is run. There is | |
2355 | a minor limitation on HP-UX systems: you must wait until the executable | |
2356 | is run in order to set breakpoints in shared library routines that are | |
2357 | not called directly by the program (for example, routines that are | |
2358 | arguments in a @code{pthread_create} call). | |
2359 | ||
2360 | @cindex watchpoints | |
2361 | @cindex memory tracing | |
2362 | @cindex breakpoint on memory address | |
2363 | @cindex breakpoint on variable modification | |
2364 | A @dfn{watchpoint} is a special breakpoint that stops your program | |
2365 | when the value of an expression changes. You must use a different | |
2366 | command to set watchpoints (@pxref{Set Watchpoints, ,Setting | |
2367 | watchpoints}), but aside from that, you can manage a watchpoint like | |
2368 | any other breakpoint: you enable, disable, and delete both breakpoints | |
2369 | and watchpoints using the same commands. | |
2370 | ||
2371 | You can arrange to have values from your program displayed automatically | |
2372 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, | |
2373 | Automatic display}. | |
2374 | ||
2375 | @cindex catchpoints | |
2376 | @cindex breakpoint on events | |
2377 | A @dfn{catchpoint} is another special breakpoint that stops your program | |
b37052ae | 2378 | when a certain kind of event occurs, such as the throwing of a C@t{++} |
c906108c SS |
2379 | exception or the loading of a library. As with watchpoints, you use a |
2380 | different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting | |
2381 | catchpoints}), but aside from that, you can manage a catchpoint like any | |
2382 | other breakpoint. (To stop when your program receives a signal, use the | |
d4f3574e | 2383 | @code{handle} command; see @ref{Signals, ,Signals}.) |
c906108c SS |
2384 | |
2385 | @cindex breakpoint numbers | |
2386 | @cindex numbers for breakpoints | |
2387 | @value{GDBN} assigns a number to each breakpoint, watchpoint, or | |
2388 | catchpoint when you create it; these numbers are successive integers | |
2389 | starting with one. In many of the commands for controlling various | |
2390 | features of breakpoints you use the breakpoint number to say which | |
2391 | breakpoint you want to change. Each breakpoint may be @dfn{enabled} or | |
2392 | @dfn{disabled}; if disabled, it has no effect on your program until you | |
2393 | enable it again. | |
2394 | ||
c5394b80 JM |
2395 | @cindex breakpoint ranges |
2396 | @cindex ranges of breakpoints | |
2397 | Some @value{GDBN} commands accept a range of breakpoints on which to | |
2398 | operate. A breakpoint range is either a single breakpoint number, like | |
2399 | @samp{5}, or two such numbers, in increasing order, separated by a | |
2400 | hyphen, like @samp{5-7}. When a breakpoint range is given to a command, | |
2401 | all breakpoint in that range are operated on. | |
2402 | ||
c906108c SS |
2403 | @menu |
2404 | * Set Breaks:: Setting breakpoints | |
2405 | * Set Watchpoints:: Setting watchpoints | |
2406 | * Set Catchpoints:: Setting catchpoints | |
2407 | * Delete Breaks:: Deleting breakpoints | |
2408 | * Disabling:: Disabling breakpoints | |
2409 | * Conditions:: Break conditions | |
2410 | * Break Commands:: Breakpoint command lists | |
c906108c | 2411 | * Breakpoint Menus:: Breakpoint menus |
d4f3574e | 2412 | * Error in Breakpoints:: ``Cannot insert breakpoints'' |
c906108c SS |
2413 | @end menu |
2414 | ||
6d2ebf8b | 2415 | @node Set Breaks |
c906108c SS |
2416 | @subsection Setting breakpoints |
2417 | ||
5d161b24 | 2418 | @c FIXME LMB what does GDB do if no code on line of breakpt? |
c906108c SS |
2419 | @c consider in particular declaration with/without initialization. |
2420 | @c | |
2421 | @c FIXME 2 is there stuff on this already? break at fun start, already init? | |
2422 | ||
2423 | @kindex break | |
41afff9a EZ |
2424 | @kindex b @r{(@code{break})} |
2425 | @vindex $bpnum@r{, convenience variable} | |
c906108c SS |
2426 | @cindex latest breakpoint |
2427 | Breakpoints are set with the @code{break} command (abbreviated | |
5d161b24 | 2428 | @code{b}). The debugger convenience variable @samp{$bpnum} records the |
f3b28801 | 2429 | number of the breakpoint you've set most recently; see @ref{Convenience |
c906108c SS |
2430 | Vars,, Convenience variables}, for a discussion of what you can do with |
2431 | convenience variables. | |
2432 | ||
2433 | You have several ways to say where the breakpoint should go. | |
2434 | ||
2435 | @table @code | |
2436 | @item break @var{function} | |
5d161b24 | 2437 | Set a breakpoint at entry to function @var{function}. |
c906108c | 2438 | When using source languages that permit overloading of symbols, such as |
b37052ae | 2439 | C@t{++}, @var{function} may refer to more than one possible place to break. |
c906108c | 2440 | @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. |
c906108c SS |
2441 | |
2442 | @item break +@var{offset} | |
2443 | @itemx break -@var{offset} | |
2444 | Set a breakpoint some number of lines forward or back from the position | |
d4f3574e | 2445 | at which execution stopped in the currently selected @dfn{stack frame}. |
2df3850c | 2446 | (@xref{Frames, ,Frames}, for a description of stack frames.) |
c906108c SS |
2447 | |
2448 | @item break @var{linenum} | |
2449 | Set a breakpoint at line @var{linenum} in the current source file. | |
d4f3574e SS |
2450 | The current source file is the last file whose source text was printed. |
2451 | The breakpoint will stop your program just before it executes any of the | |
c906108c SS |
2452 | code on that line. |
2453 | ||
2454 | @item break @var{filename}:@var{linenum} | |
2455 | Set a breakpoint at line @var{linenum} in source file @var{filename}. | |
2456 | ||
2457 | @item break @var{filename}:@var{function} | |
2458 | Set a breakpoint at entry to function @var{function} found in file | |
2459 | @var{filename}. Specifying a file name as well as a function name is | |
2460 | superfluous except when multiple files contain similarly named | |
2461 | functions. | |
2462 | ||
2463 | @item break *@var{address} | |
2464 | Set a breakpoint at address @var{address}. You can use this to set | |
2465 | breakpoints in parts of your program which do not have debugging | |
2466 | information or source files. | |
2467 | ||
2468 | @item break | |
2469 | When called without any arguments, @code{break} sets a breakpoint at | |
2470 | the next instruction to be executed in the selected stack frame | |
2471 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the | |
2472 | innermost, this makes your program stop as soon as control | |
2473 | returns to that frame. This is similar to the effect of a | |
2474 | @code{finish} command in the frame inside the selected frame---except | |
2475 | that @code{finish} does not leave an active breakpoint. If you use | |
2476 | @code{break} without an argument in the innermost frame, @value{GDBN} stops | |
2477 | the next time it reaches the current location; this may be useful | |
2478 | inside loops. | |
2479 | ||
2480 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at | |
2481 | least one instruction has been executed. If it did not do this, you | |
2482 | would be unable to proceed past a breakpoint without first disabling the | |
2483 | breakpoint. This rule applies whether or not the breakpoint already | |
2484 | existed when your program stopped. | |
2485 | ||
2486 | @item break @dots{} if @var{cond} | |
2487 | Set a breakpoint with condition @var{cond}; evaluate the expression | |
2488 | @var{cond} each time the breakpoint is reached, and stop only if the | |
2489 | value is nonzero---that is, if @var{cond} evaluates as true. | |
2490 | @samp{@dots{}} stands for one of the possible arguments described | |
2491 | above (or no argument) specifying where to break. @xref{Conditions, | |
2492 | ,Break conditions}, for more information on breakpoint conditions. | |
2493 | ||
2494 | @kindex tbreak | |
2495 | @item tbreak @var{args} | |
2496 | Set a breakpoint enabled only for one stop. @var{args} are the | |
2497 | same as for the @code{break} command, and the breakpoint is set in the same | |
2498 | way, but the breakpoint is automatically deleted after the first time your | |
2499 | program stops there. @xref{Disabling, ,Disabling breakpoints}. | |
2500 | ||
c906108c SS |
2501 | @kindex hbreak |
2502 | @item hbreak @var{args} | |
d4f3574e SS |
2503 | Set a hardware-assisted breakpoint. @var{args} are the same as for the |
2504 | @code{break} command and the breakpoint is set in the same way, but the | |
c906108c SS |
2505 | breakpoint requires hardware support and some target hardware may not |
2506 | have this support. The main purpose of this is EPROM/ROM code | |
d4f3574e SS |
2507 | debugging, so you can set a breakpoint at an instruction without |
2508 | changing the instruction. This can be used with the new trap-generation | |
2509 | provided by SPARClite DSU and some x86-based targets. These targets | |
2510 | will generate traps when a program accesses some data or instruction | |
2511 | address that is assigned to the debug registers. However the hardware | |
2512 | breakpoint registers can take a limited number of breakpoints. For | |
2513 | example, on the DSU, only two data breakpoints can be set at a time, and | |
2514 | @value{GDBN} will reject this command if more than two are used. Delete | |
2515 | or disable unused hardware breakpoints before setting new ones | |
2516 | (@pxref{Disabling, ,Disabling}). @xref{Conditions, ,Break conditions}. | |
501eef12 AC |
2517 | @xref{set remote hardware-breakpoint-limit}. |
2518 | ||
c906108c SS |
2519 | |
2520 | @kindex thbreak | |
2521 | @item thbreak @var{args} | |
2522 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} | |
2523 | are the same as for the @code{hbreak} command and the breakpoint is set in | |
5d161b24 | 2524 | the same way. However, like the @code{tbreak} command, |
c906108c SS |
2525 | the breakpoint is automatically deleted after the |
2526 | first time your program stops there. Also, like the @code{hbreak} | |
5d161b24 DB |
2527 | command, the breakpoint requires hardware support and some target hardware |
2528 | may not have this support. @xref{Disabling, ,Disabling breakpoints}. | |
d4f3574e | 2529 | See also @ref{Conditions, ,Break conditions}. |
c906108c SS |
2530 | |
2531 | @kindex rbreak | |
2532 | @cindex regular expression | |
2533 | @item rbreak @var{regex} | |
c906108c | 2534 | Set breakpoints on all functions matching the regular expression |
11cf8741 JM |
2535 | @var{regex}. This command sets an unconditional breakpoint on all |
2536 | matches, printing a list of all breakpoints it set. Once these | |
2537 | breakpoints are set, they are treated just like the breakpoints set with | |
2538 | the @code{break} command. You can delete them, disable them, or make | |
2539 | them conditional the same way as any other breakpoint. | |
2540 | ||
2541 | The syntax of the regular expression is the standard one used with tools | |
2542 | like @file{grep}. Note that this is different from the syntax used by | |
2543 | shells, so for instance @code{foo*} matches all functions that include | |
2544 | an @code{fo} followed by zero or more @code{o}s. There is an implicit | |
2545 | @code{.*} leading and trailing the regular expression you supply, so to | |
2546 | match only functions that begin with @code{foo}, use @code{^foo}. | |
c906108c | 2547 | |
b37052ae | 2548 | When debugging C@t{++} programs, @code{rbreak} is useful for setting |
c906108c SS |
2549 | breakpoints on overloaded functions that are not members of any special |
2550 | classes. | |
c906108c SS |
2551 | |
2552 | @kindex info breakpoints | |
2553 | @cindex @code{$_} and @code{info breakpoints} | |
2554 | @item info breakpoints @r{[}@var{n}@r{]} | |
2555 | @itemx info break @r{[}@var{n}@r{]} | |
2556 | @itemx info watchpoints @r{[}@var{n}@r{]} | |
2557 | Print a table of all breakpoints, watchpoints, and catchpoints set and | |
2558 | not deleted, with the following columns for each breakpoint: | |
2559 | ||
2560 | @table @emph | |
2561 | @item Breakpoint Numbers | |
2562 | @item Type | |
2563 | Breakpoint, watchpoint, or catchpoint. | |
2564 | @item Disposition | |
2565 | Whether the breakpoint is marked to be disabled or deleted when hit. | |
2566 | @item Enabled or Disabled | |
2567 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints | |
2568 | that are not enabled. | |
2569 | @item Address | |
2df3850c | 2570 | Where the breakpoint is in your program, as a memory address. |
c906108c SS |
2571 | @item What |
2572 | Where the breakpoint is in the source for your program, as a file and | |
2573 | line number. | |
2574 | @end table | |
2575 | ||
2576 | @noindent | |
2577 | If a breakpoint is conditional, @code{info break} shows the condition on | |
2578 | the line following the affected breakpoint; breakpoint commands, if any, | |
2579 | are listed after that. | |
2580 | ||
2581 | @noindent | |
2582 | @code{info break} with a breakpoint | |
2583 | number @var{n} as argument lists only that breakpoint. The | |
2584 | convenience variable @code{$_} and the default examining-address for | |
2585 | the @code{x} command are set to the address of the last breakpoint | |
5d161b24 | 2586 | listed (@pxref{Memory, ,Examining memory}). |
c906108c SS |
2587 | |
2588 | @noindent | |
2589 | @code{info break} displays a count of the number of times the breakpoint | |
2590 | has been hit. This is especially useful in conjunction with the | |
2591 | @code{ignore} command. You can ignore a large number of breakpoint | |
2592 | hits, look at the breakpoint info to see how many times the breakpoint | |
2593 | was hit, and then run again, ignoring one less than that number. This | |
2594 | will get you quickly to the last hit of that breakpoint. | |
2595 | @end table | |
2596 | ||
2597 | @value{GDBN} allows you to set any number of breakpoints at the same place in | |
2598 | your program. There is nothing silly or meaningless about this. When | |
2599 | the breakpoints are conditional, this is even useful | |
2600 | (@pxref{Conditions, ,Break conditions}). | |
2601 | ||
2602 | @cindex negative breakpoint numbers | |
2603 | @cindex internal @value{GDBN} breakpoints | |
eb12ee30 AC |
2604 | @value{GDBN} itself sometimes sets breakpoints in your program for |
2605 | special purposes, such as proper handling of @code{longjmp} (in C | |
2606 | programs). These internal breakpoints are assigned negative numbers, | |
2607 | starting with @code{-1}; @samp{info breakpoints} does not display them. | |
c906108c | 2608 | You can see these breakpoints with the @value{GDBN} maintenance command |
eb12ee30 | 2609 | @samp{maint info breakpoints} (@pxref{maint info breakpoints}). |
c906108c SS |
2610 | |
2611 | ||
6d2ebf8b | 2612 | @node Set Watchpoints |
c906108c SS |
2613 | @subsection Setting watchpoints |
2614 | ||
2615 | @cindex setting watchpoints | |
2616 | @cindex software watchpoints | |
2617 | @cindex hardware watchpoints | |
2618 | You can use a watchpoint to stop execution whenever the value of an | |
2619 | expression changes, without having to predict a particular place where | |
2620 | this may happen. | |
2621 | ||
2622 | Depending on your system, watchpoints may be implemented in software or | |
2df3850c | 2623 | hardware. @value{GDBN} does software watchpointing by single-stepping your |
c906108c SS |
2624 | program and testing the variable's value each time, which is hundreds of |
2625 | times slower than normal execution. (But this may still be worth it, to | |
2626 | catch errors where you have no clue what part of your program is the | |
2627 | culprit.) | |
2628 | ||
1104b9e7 | 2629 | On some systems, such as HP-UX, @sc{gnu}/Linux and some other x86-based targets, |
2df3850c | 2630 | @value{GDBN} includes support for |
c906108c SS |
2631 | hardware watchpoints, which do not slow down the running of your |
2632 | program. | |
2633 | ||
2634 | @table @code | |
2635 | @kindex watch | |
2636 | @item watch @var{expr} | |
2637 | Set a watchpoint for an expression. @value{GDBN} will break when @var{expr} | |
2638 | is written into by the program and its value changes. | |
2639 | ||
2640 | @kindex rwatch | |
2641 | @item rwatch @var{expr} | |
2642 | Set a watchpoint that will break when watch @var{expr} is read by the program. | |
c906108c SS |
2643 | |
2644 | @kindex awatch | |
2645 | @item awatch @var{expr} | |
2df3850c | 2646 | Set a watchpoint that will break when @var{expr} is either read or written into |
7be570e7 | 2647 | by the program. |
c906108c SS |
2648 | |
2649 | @kindex info watchpoints | |
2650 | @item info watchpoints | |
2651 | This command prints a list of watchpoints, breakpoints, and catchpoints; | |
2652 | it is the same as @code{info break}. | |
2653 | @end table | |
2654 | ||
2655 | @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware | |
2656 | watchpoints execute very quickly, and the debugger reports a change in | |
2657 | value at the exact instruction where the change occurs. If @value{GDBN} | |
2658 | cannot set a hardware watchpoint, it sets a software watchpoint, which | |
2659 | executes more slowly and reports the change in value at the next | |
2660 | statement, not the instruction, after the change occurs. | |
2661 | ||
2662 | When you issue the @code{watch} command, @value{GDBN} reports | |
2663 | ||
474c8240 | 2664 | @smallexample |
c906108c | 2665 | Hardware watchpoint @var{num}: @var{expr} |
474c8240 | 2666 | @end smallexample |
c906108c SS |
2667 | |
2668 | @noindent | |
2669 | if it was able to set a hardware watchpoint. | |
2670 | ||
7be570e7 JM |
2671 | Currently, the @code{awatch} and @code{rwatch} commands can only set |
2672 | hardware watchpoints, because accesses to data that don't change the | |
2673 | value of the watched expression cannot be detected without examining | |
2674 | every instruction as it is being executed, and @value{GDBN} does not do | |
2675 | that currently. If @value{GDBN} finds that it is unable to set a | |
2676 | hardware breakpoint with the @code{awatch} or @code{rwatch} command, it | |
2677 | will print a message like this: | |
2678 | ||
2679 | @smallexample | |
2680 | Expression cannot be implemented with read/access watchpoint. | |
2681 | @end smallexample | |
2682 | ||
2683 | Sometimes, @value{GDBN} cannot set a hardware watchpoint because the | |
2684 | data type of the watched expression is wider than what a hardware | |
2685 | watchpoint on the target machine can handle. For example, some systems | |
2686 | can only watch regions that are up to 4 bytes wide; on such systems you | |
2687 | cannot set hardware watchpoints for an expression that yields a | |
2688 | double-precision floating-point number (which is typically 8 bytes | |
2689 | wide). As a work-around, it might be possible to break the large region | |
2690 | into a series of smaller ones and watch them with separate watchpoints. | |
2691 | ||
2692 | If you set too many hardware watchpoints, @value{GDBN} might be unable | |
2693 | to insert all of them when you resume the execution of your program. | |
2694 | Since the precise number of active watchpoints is unknown until such | |
2695 | time as the program is about to be resumed, @value{GDBN} might not be | |
2696 | able to warn you about this when you set the watchpoints, and the | |
2697 | warning will be printed only when the program is resumed: | |
2698 | ||
2699 | @smallexample | |
2700 | Hardware watchpoint @var{num}: Could not insert watchpoint | |
2701 | @end smallexample | |
2702 | ||
2703 | @noindent | |
2704 | If this happens, delete or disable some of the watchpoints. | |
2705 | ||
2706 | The SPARClite DSU will generate traps when a program accesses some data | |
2707 | or instruction address that is assigned to the debug registers. For the | |
2708 | data addresses, DSU facilitates the @code{watch} command. However the | |
2709 | hardware breakpoint registers can only take two data watchpoints, and | |
2710 | both watchpoints must be the same kind. For example, you can set two | |
2711 | watchpoints with @code{watch} commands, two with @code{rwatch} commands, | |
2712 | @strong{or} two with @code{awatch} commands, but you cannot set one | |
2713 | watchpoint with one command and the other with a different command. | |
c906108c SS |
2714 | @value{GDBN} will reject the command if you try to mix watchpoints. |
2715 | Delete or disable unused watchpoint commands before setting new ones. | |
2716 | ||
2717 | If you call a function interactively using @code{print} or @code{call}, | |
2df3850c | 2718 | any watchpoints you have set will be inactive until @value{GDBN} reaches another |
c906108c SS |
2719 | kind of breakpoint or the call completes. |
2720 | ||
7be570e7 JM |
2721 | @value{GDBN} automatically deletes watchpoints that watch local |
2722 | (automatic) variables, or expressions that involve such variables, when | |
2723 | they go out of scope, that is, when the execution leaves the block in | |
2724 | which these variables were defined. In particular, when the program | |
2725 | being debugged terminates, @emph{all} local variables go out of scope, | |
2726 | and so only watchpoints that watch global variables remain set. If you | |
2727 | rerun the program, you will need to set all such watchpoints again. One | |
2728 | way of doing that would be to set a code breakpoint at the entry to the | |
2729 | @code{main} function and when it breaks, set all the watchpoints. | |
2730 | ||
c906108c SS |
2731 | @quotation |
2732 | @cindex watchpoints and threads | |
2733 | @cindex threads and watchpoints | |
c906108c SS |
2734 | @emph{Warning:} In multi-thread programs, watchpoints have only limited |
2735 | usefulness. With the current watchpoint implementation, @value{GDBN} | |
2736 | can only watch the value of an expression @emph{in a single thread}. If | |
2737 | you are confident that the expression can only change due to the current | |
2738 | thread's activity (and if you are also confident that no other thread | |
2739 | can become current), then you can use watchpoints as usual. However, | |
2740 | @value{GDBN} may not notice when a non-current thread's activity changes | |
2741 | the expression. | |
53a5351d | 2742 | |
d4f3574e | 2743 | @c FIXME: this is almost identical to the previous paragraph. |
53a5351d JM |
2744 | @emph{HP-UX Warning:} In multi-thread programs, software watchpoints |
2745 | have only limited usefulness. If @value{GDBN} creates a software | |
2746 | watchpoint, it can only watch the value of an expression @emph{in a | |
2747 | single thread}. If you are confident that the expression can only | |
2748 | change due to the current thread's activity (and if you are also | |
2749 | confident that no other thread can become current), then you can use | |
2750 | software watchpoints as usual. However, @value{GDBN} may not notice | |
2751 | when a non-current thread's activity changes the expression. (Hardware | |
2752 | watchpoints, in contrast, watch an expression in all threads.) | |
c906108c | 2753 | @end quotation |
c906108c | 2754 | |
501eef12 AC |
2755 | @xref{set remote hardware-watchpoint-limit}. |
2756 | ||
6d2ebf8b | 2757 | @node Set Catchpoints |
c906108c | 2758 | @subsection Setting catchpoints |
d4f3574e | 2759 | @cindex catchpoints, setting |
c906108c SS |
2760 | @cindex exception handlers |
2761 | @cindex event handling | |
2762 | ||
2763 | You can use @dfn{catchpoints} to cause the debugger to stop for certain | |
b37052ae | 2764 | kinds of program events, such as C@t{++} exceptions or the loading of a |
c906108c SS |
2765 | shared library. Use the @code{catch} command to set a catchpoint. |
2766 | ||
2767 | @table @code | |
2768 | @kindex catch | |
2769 | @item catch @var{event} | |
2770 | Stop when @var{event} occurs. @var{event} can be any of the following: | |
2771 | @table @code | |
2772 | @item throw | |
2773 | @kindex catch throw | |
b37052ae | 2774 | The throwing of a C@t{++} exception. |
c906108c SS |
2775 | |
2776 | @item catch | |
2777 | @kindex catch catch | |
b37052ae | 2778 | The catching of a C@t{++} exception. |
c906108c SS |
2779 | |
2780 | @item exec | |
2781 | @kindex catch exec | |
2782 | A call to @code{exec}. This is currently only available for HP-UX. | |
2783 | ||
2784 | @item fork | |
2785 | @kindex catch fork | |
2786 | A call to @code{fork}. This is currently only available for HP-UX. | |
2787 | ||
2788 | @item vfork | |
2789 | @kindex catch vfork | |
2790 | A call to @code{vfork}. This is currently only available for HP-UX. | |
2791 | ||
2792 | @item load | |
2793 | @itemx load @var{libname} | |
2794 | @kindex catch load | |
2795 | The dynamic loading of any shared library, or the loading of the library | |
2796 | @var{libname}. This is currently only available for HP-UX. | |
2797 | ||
2798 | @item unload | |
2799 | @itemx unload @var{libname} | |
2800 | @kindex catch unload | |
2801 | The unloading of any dynamically loaded shared library, or the unloading | |
2802 | of the library @var{libname}. This is currently only available for HP-UX. | |
2803 | @end table | |
2804 | ||
2805 | @item tcatch @var{event} | |
2806 | Set a catchpoint that is enabled only for one stop. The catchpoint is | |
2807 | automatically deleted after the first time the event is caught. | |
2808 | ||
2809 | @end table | |
2810 | ||
2811 | Use the @code{info break} command to list the current catchpoints. | |
2812 | ||
b37052ae | 2813 | There are currently some limitations to C@t{++} exception handling |
c906108c SS |
2814 | (@code{catch throw} and @code{catch catch}) in @value{GDBN}: |
2815 | ||
2816 | @itemize @bullet | |
2817 | @item | |
2818 | If you call a function interactively, @value{GDBN} normally returns | |
2819 | control to you when the function has finished executing. If the call | |
2820 | raises an exception, however, the call may bypass the mechanism that | |
2821 | returns control to you and cause your program either to abort or to | |
2822 | simply continue running until it hits a breakpoint, catches a signal | |
2823 | that @value{GDBN} is listening for, or exits. This is the case even if | |
2824 | you set a catchpoint for the exception; catchpoints on exceptions are | |
2825 | disabled within interactive calls. | |
2826 | ||
2827 | @item | |
2828 | You cannot raise an exception interactively. | |
2829 | ||
2830 | @item | |
2831 | You cannot install an exception handler interactively. | |
2832 | @end itemize | |
2833 | ||
2834 | @cindex raise exceptions | |
2835 | Sometimes @code{catch} is not the best way to debug exception handling: | |
2836 | if you need to know exactly where an exception is raised, it is better to | |
2837 | stop @emph{before} the exception handler is called, since that way you | |
2838 | can see the stack before any unwinding takes place. If you set a | |
2839 | breakpoint in an exception handler instead, it may not be easy to find | |
2840 | out where the exception was raised. | |
2841 | ||
2842 | To stop just before an exception handler is called, you need some | |
b37052ae | 2843 | knowledge of the implementation. In the case of @sc{gnu} C@t{++}, exceptions are |
c906108c SS |
2844 | raised by calling a library function named @code{__raise_exception} |
2845 | which has the following ANSI C interface: | |
2846 | ||
474c8240 | 2847 | @smallexample |
c906108c | 2848 | /* @var{addr} is where the exception identifier is stored. |
d4f3574e SS |
2849 | @var{id} is the exception identifier. */ |
2850 | void __raise_exception (void **addr, void *id); | |
474c8240 | 2851 | @end smallexample |
c906108c SS |
2852 | |
2853 | @noindent | |
2854 | To make the debugger catch all exceptions before any stack | |
2855 | unwinding takes place, set a breakpoint on @code{__raise_exception} | |
2856 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). | |
2857 | ||
2858 | With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) | |
2859 | that depends on the value of @var{id}, you can stop your program when | |
2860 | a specific exception is raised. You can use multiple conditional | |
2861 | breakpoints to stop your program when any of a number of exceptions are | |
2862 | raised. | |
2863 | ||
2864 | ||
6d2ebf8b | 2865 | @node Delete Breaks |
c906108c SS |
2866 | @subsection Deleting breakpoints |
2867 | ||
2868 | @cindex clearing breakpoints, watchpoints, catchpoints | |
2869 | @cindex deleting breakpoints, watchpoints, catchpoints | |
2870 | It is often necessary to eliminate a breakpoint, watchpoint, or | |
2871 | catchpoint once it has done its job and you no longer want your program | |
2872 | to stop there. This is called @dfn{deleting} the breakpoint. A | |
2873 | breakpoint that has been deleted no longer exists; it is forgotten. | |
2874 | ||
2875 | With the @code{clear} command you can delete breakpoints according to | |
2876 | where they are in your program. With the @code{delete} command you can | |
2877 | delete individual breakpoints, watchpoints, or catchpoints by specifying | |
2878 | their breakpoint numbers. | |
2879 | ||
2880 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} | |
2881 | automatically ignores breakpoints on the first instruction to be executed | |
2882 | when you continue execution without changing the execution address. | |
2883 | ||
2884 | @table @code | |
2885 | @kindex clear | |
2886 | @item clear | |
2887 | Delete any breakpoints at the next instruction to be executed in the | |
2888 | selected stack frame (@pxref{Selection, ,Selecting a frame}). When | |
2889 | the innermost frame is selected, this is a good way to delete a | |
2890 | breakpoint where your program just stopped. | |
2891 | ||
2892 | @item clear @var{function} | |
2893 | @itemx clear @var{filename}:@var{function} | |
2894 | Delete any breakpoints set at entry to the function @var{function}. | |
2895 | ||
2896 | @item clear @var{linenum} | |
2897 | @itemx clear @var{filename}:@var{linenum} | |
2898 | Delete any breakpoints set at or within the code of the specified line. | |
2899 | ||
2900 | @cindex delete breakpoints | |
2901 | @kindex delete | |
41afff9a | 2902 | @kindex d @r{(@code{delete})} |
c5394b80 JM |
2903 | @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
2904 | Delete the breakpoints, watchpoints, or catchpoints of the breakpoint | |
2905 | ranges specified as arguments. If no argument is specified, delete all | |
c906108c SS |
2906 | breakpoints (@value{GDBN} asks confirmation, unless you have @code{set |
2907 | confirm off}). You can abbreviate this command as @code{d}. | |
2908 | @end table | |
2909 | ||
6d2ebf8b | 2910 | @node Disabling |
c906108c SS |
2911 | @subsection Disabling breakpoints |
2912 | ||
2913 | @kindex disable breakpoints | |
2914 | @kindex enable breakpoints | |
2915 | Rather than deleting a breakpoint, watchpoint, or catchpoint, you might | |
2916 | prefer to @dfn{disable} it. This makes the breakpoint inoperative as if | |
2917 | it had been deleted, but remembers the information on the breakpoint so | |
2918 | that you can @dfn{enable} it again later. | |
2919 | ||
2920 | You disable and enable breakpoints, watchpoints, and catchpoints with | |
2921 | the @code{enable} and @code{disable} commands, optionally specifying one | |
2922 | or more breakpoint numbers as arguments. Use @code{info break} or | |
2923 | @code{info watch} to print a list of breakpoints, watchpoints, and | |
2924 | catchpoints if you do not know which numbers to use. | |
2925 | ||
2926 | A breakpoint, watchpoint, or catchpoint can have any of four different | |
2927 | states of enablement: | |
2928 | ||
2929 | @itemize @bullet | |
2930 | @item | |
2931 | Enabled. The breakpoint stops your program. A breakpoint set | |
2932 | with the @code{break} command starts out in this state. | |
2933 | @item | |
2934 | Disabled. The breakpoint has no effect on your program. | |
2935 | @item | |
2936 | Enabled once. The breakpoint stops your program, but then becomes | |
d4f3574e | 2937 | disabled. |
c906108c SS |
2938 | @item |
2939 | Enabled for deletion. The breakpoint stops your program, but | |
d4f3574e SS |
2940 | immediately after it does so it is deleted permanently. A breakpoint |
2941 | set with the @code{tbreak} command starts out in this state. | |
c906108c SS |
2942 | @end itemize |
2943 | ||
2944 | You can use the following commands to enable or disable breakpoints, | |
2945 | watchpoints, and catchpoints: | |
2946 | ||
2947 | @table @code | |
2948 | @kindex disable breakpoints | |
2949 | @kindex disable | |
41afff9a | 2950 | @kindex dis @r{(@code{disable})} |
c5394b80 | 2951 | @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2952 | Disable the specified breakpoints---or all breakpoints, if none are |
2953 | listed. A disabled breakpoint has no effect but is not forgotten. All | |
2954 | options such as ignore-counts, conditions and commands are remembered in | |
2955 | case the breakpoint is enabled again later. You may abbreviate | |
2956 | @code{disable} as @code{dis}. | |
2957 | ||
2958 | @kindex enable breakpoints | |
2959 | @kindex enable | |
c5394b80 | 2960 | @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2961 | Enable the specified breakpoints (or all defined breakpoints). They |
2962 | become effective once again in stopping your program. | |
2963 | ||
c5394b80 | 2964 | @item enable @r{[}breakpoints@r{]} once @var{range}@dots{} |
c906108c SS |
2965 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
2966 | of these breakpoints immediately after stopping your program. | |
2967 | ||
c5394b80 | 2968 | @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{} |
c906108c SS |
2969 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
2970 | deletes any of these breakpoints as soon as your program stops there. | |
2971 | @end table | |
2972 | ||
d4f3574e SS |
2973 | @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is |
2974 | @c confusing: tbreak is also initially enabled. | |
c906108c SS |
2975 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
2976 | ,Setting breakpoints}), breakpoints that you set are initially enabled; | |
2977 | subsequently, they become disabled or enabled only when you use one of | |
2978 | the commands above. (The command @code{until} can set and delete a | |
2979 | breakpoint of its own, but it does not change the state of your other | |
2980 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and | |
2981 | stepping}.) | |
2982 | ||
6d2ebf8b | 2983 | @node Conditions |
c906108c SS |
2984 | @subsection Break conditions |
2985 | @cindex conditional breakpoints | |
2986 | @cindex breakpoint conditions | |
2987 | ||
2988 | @c FIXME what is scope of break condition expr? Context where wanted? | |
5d161b24 | 2989 | @c in particular for a watchpoint? |
c906108c SS |
2990 | The simplest sort of breakpoint breaks every time your program reaches a |
2991 | specified place. You can also specify a @dfn{condition} for a | |
2992 | breakpoint. A condition is just a Boolean expression in your | |
2993 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with | |
2994 | a condition evaluates the expression each time your program reaches it, | |
2995 | and your program stops only if the condition is @emph{true}. | |
2996 | ||
2997 | This is the converse of using assertions for program validation; in that | |
2998 | situation, you want to stop when the assertion is violated---that is, | |
2999 | when the condition is false. In C, if you want to test an assertion expressed | |
3000 | by the condition @var{assert}, you should set the condition | |
3001 | @samp{! @var{assert}} on the appropriate breakpoint. | |
3002 | ||
3003 | Conditions are also accepted for watchpoints; you may not need them, | |
3004 | since a watchpoint is inspecting the value of an expression anyhow---but | |
3005 | it might be simpler, say, to just set a watchpoint on a variable name, | |
3006 | and specify a condition that tests whether the new value is an interesting | |
3007 | one. | |
3008 | ||
3009 | Break conditions can have side effects, and may even call functions in | |
3010 | your program. This can be useful, for example, to activate functions | |
3011 | that log program progress, or to use your own print functions to | |
3012 | format special data structures. The effects are completely predictable | |
3013 | unless there is another enabled breakpoint at the same address. (In | |
3014 | that case, @value{GDBN} might see the other breakpoint first and stop your | |
3015 | program without checking the condition of this one.) Note that | |
d4f3574e SS |
3016 | breakpoint commands are usually more convenient and flexible than break |
3017 | conditions for the | |
c906108c SS |
3018 | purpose of performing side effects when a breakpoint is reached |
3019 | (@pxref{Break Commands, ,Breakpoint command lists}). | |
3020 | ||
3021 | Break conditions can be specified when a breakpoint is set, by using | |
3022 | @samp{if} in the arguments to the @code{break} command. @xref{Set | |
3023 | Breaks, ,Setting breakpoints}. They can also be changed at any time | |
3024 | with the @code{condition} command. | |
53a5351d | 3025 | |
c906108c SS |
3026 | You can also use the @code{if} keyword with the @code{watch} command. |
3027 | The @code{catch} command does not recognize the @code{if} keyword; | |
3028 | @code{condition} is the only way to impose a further condition on a | |
3029 | catchpoint. | |
c906108c SS |
3030 | |
3031 | @table @code | |
3032 | @kindex condition | |
3033 | @item condition @var{bnum} @var{expression} | |
3034 | Specify @var{expression} as the break condition for breakpoint, | |
3035 | watchpoint, or catchpoint number @var{bnum}. After you set a condition, | |
3036 | breakpoint @var{bnum} stops your program only if the value of | |
3037 | @var{expression} is true (nonzero, in C). When you use | |
3038 | @code{condition}, @value{GDBN} checks @var{expression} immediately for | |
3039 | syntactic correctness, and to determine whether symbols in it have | |
d4f3574e SS |
3040 | referents in the context of your breakpoint. If @var{expression} uses |
3041 | symbols not referenced in the context of the breakpoint, @value{GDBN} | |
3042 | prints an error message: | |
3043 | ||
474c8240 | 3044 | @smallexample |
d4f3574e | 3045 | No symbol "foo" in current context. |
474c8240 | 3046 | @end smallexample |
d4f3574e SS |
3047 | |
3048 | @noindent | |
c906108c SS |
3049 | @value{GDBN} does |
3050 | not actually evaluate @var{expression} at the time the @code{condition} | |
d4f3574e SS |
3051 | command (or a command that sets a breakpoint with a condition, like |
3052 | @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}. | |
c906108c SS |
3053 | |
3054 | @item condition @var{bnum} | |
3055 | Remove the condition from breakpoint number @var{bnum}. It becomes | |
3056 | an ordinary unconditional breakpoint. | |
3057 | @end table | |
3058 | ||
3059 | @cindex ignore count (of breakpoint) | |
3060 | A special case of a breakpoint condition is to stop only when the | |
3061 | breakpoint has been reached a certain number of times. This is so | |
3062 | useful that there is a special way to do it, using the @dfn{ignore | |
3063 | count} of the breakpoint. Every breakpoint has an ignore count, which | |
3064 | is an integer. Most of the time, the ignore count is zero, and | |
3065 | therefore has no effect. But if your program reaches a breakpoint whose | |
3066 | ignore count is positive, then instead of stopping, it just decrements | |
3067 | the ignore count by one and continues. As a result, if the ignore count | |
3068 | value is @var{n}, the breakpoint does not stop the next @var{n} times | |
3069 | your program reaches it. | |
3070 | ||
3071 | @table @code | |
3072 | @kindex ignore | |
3073 | @item ignore @var{bnum} @var{count} | |
3074 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. | |
3075 | The next @var{count} times the breakpoint is reached, your program's | |
3076 | execution does not stop; other than to decrement the ignore count, @value{GDBN} | |
3077 | takes no action. | |
3078 | ||
3079 | To make the breakpoint stop the next time it is reached, specify | |
3080 | a count of zero. | |
3081 | ||
3082 | When you use @code{continue} to resume execution of your program from a | |
3083 | breakpoint, you can specify an ignore count directly as an argument to | |
3084 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and | |
3085 | Stepping,,Continuing and stepping}. | |
3086 | ||
3087 | If a breakpoint has a positive ignore count and a condition, the | |
3088 | condition is not checked. Once the ignore count reaches zero, | |
3089 | @value{GDBN} resumes checking the condition. | |
3090 | ||
3091 | You could achieve the effect of the ignore count with a condition such | |
3092 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that | |
3093 | is decremented each time. @xref{Convenience Vars, ,Convenience | |
3094 | variables}. | |
3095 | @end table | |
3096 | ||
3097 | Ignore counts apply to breakpoints, watchpoints, and catchpoints. | |
3098 | ||
3099 | ||
6d2ebf8b | 3100 | @node Break Commands |
c906108c SS |
3101 | @subsection Breakpoint command lists |
3102 | ||
3103 | @cindex breakpoint commands | |
3104 | You can give any breakpoint (or watchpoint or catchpoint) a series of | |
3105 | commands to execute when your program stops due to that breakpoint. For | |
3106 | example, you might want to print the values of certain expressions, or | |
3107 | enable other breakpoints. | |
3108 | ||
3109 | @table @code | |
3110 | @kindex commands | |
3111 | @kindex end | |
3112 | @item commands @r{[}@var{bnum}@r{]} | |
3113 | @itemx @dots{} @var{command-list} @dots{} | |
3114 | @itemx end | |
3115 | Specify a list of commands for breakpoint number @var{bnum}. The commands | |
3116 | themselves appear on the following lines. Type a line containing just | |
3117 | @code{end} to terminate the commands. | |
3118 | ||
3119 | To remove all commands from a breakpoint, type @code{commands} and | |
3120 | follow it immediately with @code{end}; that is, give no commands. | |
3121 | ||
3122 | With no @var{bnum} argument, @code{commands} refers to the last | |
3123 | breakpoint, watchpoint, or catchpoint set (not to the breakpoint most | |
3124 | recently encountered). | |
3125 | @end table | |
3126 | ||
3127 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is | |
3128 | disabled within a @var{command-list}. | |
3129 | ||
3130 | You can use breakpoint commands to start your program up again. Simply | |
3131 | use the @code{continue} command, or @code{step}, or any other command | |
3132 | that resumes execution. | |
3133 | ||
3134 | Any other commands in the command list, after a command that resumes | |
3135 | execution, are ignored. This is because any time you resume execution | |
3136 | (even with a simple @code{next} or @code{step}), you may encounter | |
3137 | another breakpoint---which could have its own command list, leading to | |
3138 | ambiguities about which list to execute. | |
3139 | ||
3140 | @kindex silent | |
3141 | If the first command you specify in a command list is @code{silent}, the | |
3142 | usual message about stopping at a breakpoint is not printed. This may | |
3143 | be desirable for breakpoints that are to print a specific message and | |
3144 | then continue. If none of the remaining commands print anything, you | |
3145 | see no sign that the breakpoint was reached. @code{silent} is | |
3146 | meaningful only at the beginning of a breakpoint command list. | |
3147 | ||
3148 | The commands @code{echo}, @code{output}, and @code{printf} allow you to | |
3149 | print precisely controlled output, and are often useful in silent | |
3150 | breakpoints. @xref{Output, ,Commands for controlled output}. | |
3151 | ||
3152 | For example, here is how you could use breakpoint commands to print the | |
3153 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. | |
3154 | ||
474c8240 | 3155 | @smallexample |
c906108c SS |
3156 | break foo if x>0 |
3157 | commands | |
3158 | silent | |
3159 | printf "x is %d\n",x | |
3160 | cont | |
3161 | end | |
474c8240 | 3162 | @end smallexample |
c906108c SS |
3163 | |
3164 | One application for breakpoint commands is to compensate for one bug so | |
3165 | you can test for another. Put a breakpoint just after the erroneous line | |
3166 | of code, give it a condition to detect the case in which something | |
3167 | erroneous has been done, and give it commands to assign correct values | |
3168 | to any variables that need them. End with the @code{continue} command | |
3169 | so that your program does not stop, and start with the @code{silent} | |
3170 | command so that no output is produced. Here is an example: | |
3171 | ||
474c8240 | 3172 | @smallexample |
c906108c SS |
3173 | break 403 |
3174 | commands | |
3175 | silent | |
3176 | set x = y + 4 | |
3177 | cont | |
3178 | end | |
474c8240 | 3179 | @end smallexample |
c906108c | 3180 | |
6d2ebf8b | 3181 | @node Breakpoint Menus |
c906108c SS |
3182 | @subsection Breakpoint menus |
3183 | @cindex overloading | |
3184 | @cindex symbol overloading | |
3185 | ||
b37052ae | 3186 | Some programming languages (notably C@t{++}) permit a single function name |
c906108c SS |
3187 | to be defined several times, for application in different contexts. |
3188 | This is called @dfn{overloading}. When a function name is overloaded, | |
3189 | @samp{break @var{function}} is not enough to tell @value{GDBN} where you want | |
3190 | a breakpoint. If you realize this is a problem, you can use | |
3191 | something like @samp{break @var{function}(@var{types})} to specify which | |
3192 | particular version of the function you want. Otherwise, @value{GDBN} offers | |
3193 | you a menu of numbered choices for different possible breakpoints, and | |
3194 | waits for your selection with the prompt @samp{>}. The first two | |
3195 | options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} | |
3196 | sets a breakpoint at each definition of @var{function}, and typing | |
3197 | @kbd{0} aborts the @code{break} command without setting any new | |
3198 | breakpoints. | |
3199 | ||
3200 | For example, the following session excerpt shows an attempt to set a | |
3201 | breakpoint at the overloaded symbol @code{String::after}. | |
3202 | We choose three particular definitions of that function name: | |
3203 | ||
3204 | @c FIXME! This is likely to change to show arg type lists, at least | |
3205 | @smallexample | |
3206 | @group | |
3207 | (@value{GDBP}) b String::after | |
3208 | [0] cancel | |
3209 | [1] all | |
3210 | [2] file:String.cc; line number:867 | |
3211 | [3] file:String.cc; line number:860 | |
3212 | [4] file:String.cc; line number:875 | |
3213 | [5] file:String.cc; line number:853 | |
3214 | [6] file:String.cc; line number:846 | |
3215 | [7] file:String.cc; line number:735 | |
3216 | > 2 4 6 | |
3217 | Breakpoint 1 at 0xb26c: file String.cc, line 867. | |
3218 | Breakpoint 2 at 0xb344: file String.cc, line 875. | |
3219 | Breakpoint 3 at 0xafcc: file String.cc, line 846. | |
3220 | Multiple breakpoints were set. | |
3221 | Use the "delete" command to delete unwanted | |
3222 | breakpoints. | |
3223 | (@value{GDBP}) | |
3224 | @end group | |
3225 | @end smallexample | |
c906108c SS |
3226 | |
3227 | @c @ifclear BARETARGET | |
6d2ebf8b | 3228 | @node Error in Breakpoints |
d4f3574e | 3229 | @subsection ``Cannot insert breakpoints'' |
c906108c SS |
3230 | @c |
3231 | @c FIXME!! 14/6/95 Is there a real example of this? Let's use it. | |
3232 | @c | |
d4f3574e SS |
3233 | Under some operating systems, breakpoints cannot be used in a program if |
3234 | any other process is running that program. In this situation, | |
5d161b24 | 3235 | attempting to run or continue a program with a breakpoint causes |
d4f3574e SS |
3236 | @value{GDBN} to print an error message: |
3237 | ||
474c8240 | 3238 | @smallexample |
d4f3574e SS |
3239 | Cannot insert breakpoints. |
3240 | The same program may be running in another process. | |
474c8240 | 3241 | @end smallexample |
d4f3574e SS |
3242 | |
3243 | When this happens, you have three ways to proceed: | |
3244 | ||
3245 | @enumerate | |
3246 | @item | |
3247 | Remove or disable the breakpoints, then continue. | |
3248 | ||
3249 | @item | |
5d161b24 | 3250 | Suspend @value{GDBN}, and copy the file containing your program to a new |
d4f3574e | 3251 | name. Resume @value{GDBN} and use the @code{exec-file} command to specify |
5d161b24 | 3252 | that @value{GDBN} should run your program under that name. |
d4f3574e SS |
3253 | Then start your program again. |
3254 | ||
3255 | @item | |
3256 | Relink your program so that the text segment is nonsharable, using the | |
3257 | linker option @samp{-N}. The operating system limitation may not apply | |
3258 | to nonsharable executables. | |
3259 | @end enumerate | |
c906108c SS |
3260 | @c @end ifclear |
3261 | ||
d4f3574e SS |
3262 | A similar message can be printed if you request too many active |
3263 | hardware-assisted breakpoints and watchpoints: | |
3264 | ||
3265 | @c FIXME: the precise wording of this message may change; the relevant | |
3266 | @c source change is not committed yet (Sep 3, 1999). | |
3267 | @smallexample | |
3268 | Stopped; cannot insert breakpoints. | |
3269 | You may have requested too many hardware breakpoints and watchpoints. | |
3270 | @end smallexample | |
3271 | ||
3272 | @noindent | |
3273 | This message is printed when you attempt to resume the program, since | |
3274 | only then @value{GDBN} knows exactly how many hardware breakpoints and | |
3275 | watchpoints it needs to insert. | |
3276 | ||
3277 | When this message is printed, you need to disable or remove some of the | |
3278 | hardware-assisted breakpoints and watchpoints, and then continue. | |
3279 | ||
3280 | ||
6d2ebf8b | 3281 | @node Continuing and Stepping |
c906108c SS |
3282 | @section Continuing and stepping |
3283 | ||
3284 | @cindex stepping | |
3285 | @cindex continuing | |
3286 | @cindex resuming execution | |
3287 | @dfn{Continuing} means resuming program execution until your program | |
3288 | completes normally. In contrast, @dfn{stepping} means executing just | |
3289 | one more ``step'' of your program, where ``step'' may mean either one | |
3290 | line of source code, or one machine instruction (depending on what | |
7a292a7a SS |
3291 | particular command you use). Either when continuing or when stepping, |
3292 | your program may stop even sooner, due to a breakpoint or a signal. (If | |
d4f3574e SS |
3293 | it stops due to a signal, you may want to use @code{handle}, or use |
3294 | @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.) | |
c906108c SS |
3295 | |
3296 | @table @code | |
3297 | @kindex continue | |
41afff9a EZ |
3298 | @kindex c @r{(@code{continue})} |
3299 | @kindex fg @r{(resume foreground execution)} | |
c906108c SS |
3300 | @item continue @r{[}@var{ignore-count}@r{]} |
3301 | @itemx c @r{[}@var{ignore-count}@r{]} | |
3302 | @itemx fg @r{[}@var{ignore-count}@r{]} | |
3303 | Resume program execution, at the address where your program last stopped; | |
3304 | any breakpoints set at that address are bypassed. The optional argument | |
3305 | @var{ignore-count} allows you to specify a further number of times to | |
3306 | ignore a breakpoint at this location; its effect is like that of | |
3307 | @code{ignore} (@pxref{Conditions, ,Break conditions}). | |
3308 | ||
3309 | The argument @var{ignore-count} is meaningful only when your program | |
3310 | stopped due to a breakpoint. At other times, the argument to | |
3311 | @code{continue} is ignored. | |
3312 | ||
d4f3574e SS |
3313 | The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the |
3314 | debugged program is deemed to be the foreground program) are provided | |
3315 | purely for convenience, and have exactly the same behavior as | |
3316 | @code{continue}. | |
c906108c SS |
3317 | @end table |
3318 | ||
3319 | To resume execution at a different place, you can use @code{return} | |
3320 | (@pxref{Returning, ,Returning from a function}) to go back to the | |
3321 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a | |
3322 | different address}) to go to an arbitrary location in your program. | |
3323 | ||
3324 | A typical technique for using stepping is to set a breakpoint | |
3325 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and catchpoints}) at the | |
3326 | beginning of the function or the section of your program where a problem | |
3327 | is believed to lie, run your program until it stops at that breakpoint, | |
3328 | and then step through the suspect area, examining the variables that are | |
3329 | interesting, until you see the problem happen. | |
3330 | ||
3331 | @table @code | |
3332 | @kindex step | |
41afff9a | 3333 | @kindex s @r{(@code{step})} |
c906108c SS |
3334 | @item step |
3335 | Continue running your program until control reaches a different source | |
3336 | line, then stop it and return control to @value{GDBN}. This command is | |
3337 | abbreviated @code{s}. | |
3338 | ||
3339 | @quotation | |
3340 | @c "without debugging information" is imprecise; actually "without line | |
3341 | @c numbers in the debugging information". (gcc -g1 has debugging info but | |
3342 | @c not line numbers). But it seems complex to try to make that | |
3343 | @c distinction here. | |
3344 | @emph{Warning:} If you use the @code{step} command while control is | |
3345 | within a function that was compiled without debugging information, | |
3346 | execution proceeds until control reaches a function that does have | |
3347 | debugging information. Likewise, it will not step into a function which | |
3348 | is compiled without debugging information. To step through functions | |
3349 | without debugging information, use the @code{stepi} command, described | |
3350 | below. | |
3351 | @end quotation | |
3352 | ||
4a92d011 EZ |
3353 | The @code{step} command only stops at the first instruction of a source |
3354 | line. This prevents the multiple stops that could otherwise occur in | |
3355 | @code{switch} statements, @code{for} loops, etc. @code{step} continues | |
3356 | to stop if a function that has debugging information is called within | |
3357 | the line. In other words, @code{step} @emph{steps inside} any functions | |
3358 | called within the line. | |
c906108c | 3359 | |
d4f3574e SS |
3360 | Also, the @code{step} command only enters a function if there is line |
3361 | number information for the function. Otherwise it acts like the | |
5d161b24 | 3362 | @code{next} command. This avoids problems when using @code{cc -gl} |
c906108c | 3363 | on MIPS machines. Previously, @code{step} entered subroutines if there |
5d161b24 | 3364 | was any debugging information about the routine. |
c906108c SS |
3365 | |
3366 | @item step @var{count} | |
3367 | Continue running as in @code{step}, but do so @var{count} times. If a | |
7a292a7a SS |
3368 | breakpoint is reached, or a signal not related to stepping occurs before |
3369 | @var{count} steps, stepping stops right away. | |
c906108c SS |
3370 | |
3371 | @kindex next | |
41afff9a | 3372 | @kindex n @r{(@code{next})} |
c906108c SS |
3373 | @item next @r{[}@var{count}@r{]} |
3374 | Continue to the next source line in the current (innermost) stack frame. | |
7a292a7a SS |
3375 | This is similar to @code{step}, but function calls that appear within |
3376 | the line of code are executed without stopping. Execution stops when | |
3377 | control reaches a different line of code at the original stack level | |
3378 | that was executing when you gave the @code{next} command. This command | |
3379 | is abbreviated @code{n}. | |
c906108c SS |
3380 | |
3381 | An argument @var{count} is a repeat count, as for @code{step}. | |
3382 | ||
3383 | ||
3384 | @c FIX ME!! Do we delete this, or is there a way it fits in with | |
3385 | @c the following paragraph? --- Vctoria | |
3386 | @c | |
3387 | @c @code{next} within a function that lacks debugging information acts like | |
3388 | @c @code{step}, but any function calls appearing within the code of the | |
3389 | @c function are executed without stopping. | |
3390 | ||
d4f3574e SS |
3391 | The @code{next} command only stops at the first instruction of a |
3392 | source line. This prevents multiple stops that could otherwise occur in | |
4a92d011 | 3393 | @code{switch} statements, @code{for} loops, etc. |
c906108c | 3394 | |
b90a5f51 CF |
3395 | @kindex set step-mode |
3396 | @item set step-mode | |
3397 | @cindex functions without line info, and stepping | |
3398 | @cindex stepping into functions with no line info | |
3399 | @itemx set step-mode on | |
4a92d011 | 3400 | The @code{set step-mode on} command causes the @code{step} command to |
b90a5f51 CF |
3401 | stop at the first instruction of a function which contains no debug line |
3402 | information rather than stepping over it. | |
3403 | ||
4a92d011 EZ |
3404 | This is useful in cases where you may be interested in inspecting the |
3405 | machine instructions of a function which has no symbolic info and do not | |
3406 | want @value{GDBN} to automatically skip over this function. | |
b90a5f51 CF |
3407 | |
3408 | @item set step-mode off | |
4a92d011 | 3409 | Causes the @code{step} command to step over any functions which contains no |
b90a5f51 CF |
3410 | debug information. This is the default. |
3411 | ||
c906108c SS |
3412 | @kindex finish |
3413 | @item finish | |
3414 | Continue running until just after function in the selected stack frame | |
3415 | returns. Print the returned value (if any). | |
3416 | ||
3417 | Contrast this with the @code{return} command (@pxref{Returning, | |
3418 | ,Returning from a function}). | |
3419 | ||
3420 | @kindex until | |
41afff9a | 3421 | @kindex u @r{(@code{until})} |
c906108c SS |
3422 | @item until |
3423 | @itemx u | |
3424 | Continue running until a source line past the current line, in the | |
3425 | current stack frame, is reached. This command is used to avoid single | |
3426 | stepping through a loop more than once. It is like the @code{next} | |
3427 | command, except that when @code{until} encounters a jump, it | |
3428 | automatically continues execution until the program counter is greater | |
3429 | than the address of the jump. | |
3430 | ||
3431 | This means that when you reach the end of a loop after single stepping | |
3432 | though it, @code{until} makes your program continue execution until it | |
3433 | exits the loop. In contrast, a @code{next} command at the end of a loop | |
3434 | simply steps back to the beginning of the loop, which forces you to step | |
3435 | through the next iteration. | |
3436 | ||
3437 | @code{until} always stops your program if it attempts to exit the current | |
3438 | stack frame. | |
3439 | ||
3440 | @code{until} may produce somewhat counterintuitive results if the order | |
3441 | of machine code does not match the order of the source lines. For | |
3442 | example, in the following excerpt from a debugging session, the @code{f} | |
3443 | (@code{frame}) command shows that execution is stopped at line | |
3444 | @code{206}; yet when we use @code{until}, we get to line @code{195}: | |
3445 | ||
474c8240 | 3446 | @smallexample |
c906108c SS |
3447 | (@value{GDBP}) f |
3448 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 | |
3449 | 206 expand_input(); | |
3450 | (@value{GDBP}) until | |
3451 | 195 for ( ; argc > 0; NEXTARG) @{ | |
474c8240 | 3452 | @end smallexample |
c906108c SS |
3453 | |
3454 | This happened because, for execution efficiency, the compiler had | |
3455 | generated code for the loop closure test at the end, rather than the | |
3456 | start, of the loop---even though the test in a C @code{for}-loop is | |
3457 | written before the body of the loop. The @code{until} command appeared | |
3458 | to step back to the beginning of the loop when it advanced to this | |
3459 | expression; however, it has not really gone to an earlier | |
3460 | statement---not in terms of the actual machine code. | |
3461 | ||
3462 | @code{until} with no argument works by means of single | |
3463 | instruction stepping, and hence is slower than @code{until} with an | |
3464 | argument. | |
3465 | ||
3466 | @item until @var{location} | |
3467 | @itemx u @var{location} | |
3468 | Continue running your program until either the specified location is | |
3469 | reached, or the current stack frame returns. @var{location} is any of | |
3470 | the forms of argument acceptable to @code{break} (@pxref{Set Breaks, | |
c60eb6f1 EZ |
3471 | ,Setting breakpoints}). This form of the command uses breakpoints, and |
3472 | hence is quicker than @code{until} without an argument. The specified | |
3473 | location is actually reached only if it is in the current frame. This | |
3474 | implies that @code{until} can be used to skip over recursive function | |
3475 | invocations. For instance in the code below, if the current location is | |
3476 | line @code{96}, issuing @code{until 99} will execute the program up to | |
3477 | line @code{99} in the same invocation of factorial, i.e. after the inner | |
3478 | invocations have returned. | |
3479 | ||
3480 | @smallexample | |
3481 | 94 int factorial (int value) | |
3482 | 95 @{ | |
3483 | 96 if (value > 1) @{ | |
3484 | 97 value *= factorial (value - 1); | |
3485 | 98 @} | |
3486 | 99 return (value); | |
3487 | 100 @} | |
3488 | @end smallexample | |
3489 | ||
3490 | ||
3491 | @kindex advance @var{location} | |
3492 | @itemx advance @var{location} | |
3493 | Continue running the program up to the given location. An argument is | |
3494 | required, anything of the same form as arguments for the @code{break} | |
3495 | command. Execution will also stop upon exit from the current stack | |
3496 | frame. This command is similar to @code{until}, but @code{advance} will | |
3497 | not skip over recursive function calls, and the target location doesn't | |
3498 | have to be in the same frame as the current one. | |
3499 | ||
c906108c SS |
3500 | |
3501 | @kindex stepi | |
41afff9a | 3502 | @kindex si @r{(@code{stepi})} |
c906108c | 3503 | @item stepi |
96a2c332 | 3504 | @itemx stepi @var{arg} |
c906108c SS |
3505 | @itemx si |
3506 | Execute one machine instruction, then stop and return to the debugger. | |
3507 | ||
3508 | It is often useful to do @samp{display/i $pc} when stepping by machine | |
3509 | instructions. This makes @value{GDBN} automatically display the next | |
3510 | instruction to be executed, each time your program stops. @xref{Auto | |
3511 | Display,, Automatic display}. | |
3512 | ||
3513 | An argument is a repeat count, as in @code{step}. | |
3514 | ||
3515 | @need 750 | |
3516 | @kindex nexti | |
41afff9a | 3517 | @kindex ni @r{(@code{nexti})} |
c906108c | 3518 | @item nexti |
96a2c332 | 3519 | @itemx nexti @var{arg} |
c906108c SS |
3520 | @itemx ni |
3521 | Execute one machine instruction, but if it is a function call, | |
3522 | proceed until the function returns. | |
3523 | ||
3524 | An argument is a repeat count, as in @code{next}. | |
3525 | @end table | |
3526 | ||
6d2ebf8b | 3527 | @node Signals |
c906108c SS |
3528 | @section Signals |
3529 | @cindex signals | |
3530 | ||
3531 | A signal is an asynchronous event that can happen in a program. The | |
3532 | operating system defines the possible kinds of signals, and gives each | |
3533 | kind a name and a number. For example, in Unix @code{SIGINT} is the | |
d4f3574e | 3534 | signal a program gets when you type an interrupt character (often @kbd{C-c}); |
c906108c SS |
3535 | @code{SIGSEGV} is the signal a program gets from referencing a place in |
3536 | memory far away from all the areas in use; @code{SIGALRM} occurs when | |
3537 | the alarm clock timer goes off (which happens only if your program has | |
3538 | requested an alarm). | |
3539 | ||
3540 | @cindex fatal signals | |
3541 | Some signals, including @code{SIGALRM}, are a normal part of the | |
3542 | functioning of your program. Others, such as @code{SIGSEGV}, indicate | |
d4f3574e | 3543 | errors; these signals are @dfn{fatal} (they kill your program immediately) if the |
c906108c SS |
3544 | program has not specified in advance some other way to handle the signal. |
3545 | @code{SIGINT} does not indicate an error in your program, but it is normally | |
3546 | fatal so it can carry out the purpose of the interrupt: to kill the program. | |
3547 | ||
3548 | @value{GDBN} has the ability to detect any occurrence of a signal in your | |
3549 | program. You can tell @value{GDBN} in advance what to do for each kind of | |
3550 | signal. | |
3551 | ||
3552 | @cindex handling signals | |
24f93129 EZ |
3553 | Normally, @value{GDBN} is set up to let the non-erroneous signals like |
3554 | @code{SIGALRM} be silently passed to your program | |
3555 | (so as not to interfere with their role in the program's functioning) | |
c906108c SS |
3556 | but to stop your program immediately whenever an error signal happens. |
3557 | You can change these settings with the @code{handle} command. | |
3558 | ||
3559 | @table @code | |
3560 | @kindex info signals | |
3561 | @item info signals | |
96a2c332 | 3562 | @itemx info handle |
c906108c SS |
3563 | Print a table of all the kinds of signals and how @value{GDBN} has been told to |
3564 | handle each one. You can use this to see the signal numbers of all | |
3565 | the defined types of signals. | |
3566 | ||
d4f3574e | 3567 | @code{info handle} is an alias for @code{info signals}. |
c906108c SS |
3568 | |
3569 | @kindex handle | |
3570 | @item handle @var{signal} @var{keywords}@dots{} | |
5ece1a18 EZ |
3571 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} |
3572 | can be the number of a signal or its name (with or without the | |
24f93129 | 3573 | @samp{SIG} at the beginning); a list of signal numbers of the form |
5ece1a18 EZ |
3574 | @samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the |
3575 | known signals. The @var{keywords} say what change to make. | |
c906108c SS |
3576 | @end table |
3577 | ||
3578 | @c @group | |
3579 | The keywords allowed by the @code{handle} command can be abbreviated. | |
3580 | Their full names are: | |
3581 | ||
3582 | @table @code | |
3583 | @item nostop | |
3584 | @value{GDBN} should not stop your program when this signal happens. It may | |
3585 | still print a message telling you that the signal has come in. | |
3586 | ||
3587 | @item stop | |
3588 | @value{GDBN} should stop your program when this signal happens. This implies | |
3589 | the @code{print} keyword as well. | |
3590 | ||
3591 | @item print | |
3592 | @value{GDBN} should print a message when this signal happens. | |
3593 | ||
3594 | @item noprint | |
3595 | @value{GDBN} should not mention the occurrence of the signal at all. This | |
3596 | implies the @code{nostop} keyword as well. | |
3597 | ||
3598 | @item pass | |
5ece1a18 | 3599 | @itemx noignore |
c906108c SS |
3600 | @value{GDBN} should allow your program to see this signal; your program |
3601 | can handle the signal, or else it may terminate if the signal is fatal | |
5ece1a18 | 3602 | and not handled. @code{pass} and @code{noignore} are synonyms. |
c906108c SS |
3603 | |
3604 | @item nopass | |
5ece1a18 | 3605 | @itemx ignore |
c906108c | 3606 | @value{GDBN} should not allow your program to see this signal. |
5ece1a18 | 3607 | @code{nopass} and @code{ignore} are synonyms. |
c906108c SS |
3608 | @end table |
3609 | @c @end group | |
3610 | ||
d4f3574e SS |
3611 | When a signal stops your program, the signal is not visible to the |
3612 | program until you | |
c906108c SS |
3613 | continue. Your program sees the signal then, if @code{pass} is in |
3614 | effect for the signal in question @emph{at that time}. In other words, | |
3615 | after @value{GDBN} reports a signal, you can use the @code{handle} | |
3616 | command with @code{pass} or @code{nopass} to control whether your | |
3617 | program sees that signal when you continue. | |
3618 | ||
24f93129 EZ |
3619 | The default is set to @code{nostop}, @code{noprint}, @code{pass} for |
3620 | non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and | |
3621 | @code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the | |
3622 | erroneous signals. | |
3623 | ||
c906108c SS |
3624 | You can also use the @code{signal} command to prevent your program from |
3625 | seeing a signal, or cause it to see a signal it normally would not see, | |
3626 | or to give it any signal at any time. For example, if your program stopped | |
3627 | due to some sort of memory reference error, you might store correct | |
3628 | values into the erroneous variables and continue, hoping to see more | |
3629 | execution; but your program would probably terminate immediately as | |
3630 | a result of the fatal signal once it saw the signal. To prevent this, | |
3631 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your | |
5d161b24 | 3632 | program a signal}. |
c906108c | 3633 | |
6d2ebf8b | 3634 | @node Thread Stops |
c906108c SS |
3635 | @section Stopping and starting multi-thread programs |
3636 | ||
3637 | When your program has multiple threads (@pxref{Threads,, Debugging | |
3638 | programs with multiple threads}), you can choose whether to set | |
3639 | breakpoints on all threads, or on a particular thread. | |
3640 | ||
3641 | @table @code | |
3642 | @cindex breakpoints and threads | |
3643 | @cindex thread breakpoints | |
3644 | @kindex break @dots{} thread @var{threadno} | |
3645 | @item break @var{linespec} thread @var{threadno} | |
3646 | @itemx break @var{linespec} thread @var{threadno} if @dots{} | |
3647 | @var{linespec} specifies source lines; there are several ways of | |
3648 | writing them, but the effect is always to specify some source line. | |
3649 | ||
3650 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command | |
3651 | to specify that you only want @value{GDBN} to stop the program when a | |
3652 | particular thread reaches this breakpoint. @var{threadno} is one of the | |
3653 | numeric thread identifiers assigned by @value{GDBN}, shown in the first | |
3654 | column of the @samp{info threads} display. | |
3655 | ||
3656 | If you do not specify @samp{thread @var{threadno}} when you set a | |
3657 | breakpoint, the breakpoint applies to @emph{all} threads of your | |
3658 | program. | |
3659 | ||
3660 | You can use the @code{thread} qualifier on conditional breakpoints as | |
3661 | well; in this case, place @samp{thread @var{threadno}} before the | |
3662 | breakpoint condition, like this: | |
3663 | ||
3664 | @smallexample | |
2df3850c | 3665 | (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim |
c906108c SS |
3666 | @end smallexample |
3667 | ||
3668 | @end table | |
3669 | ||
3670 | @cindex stopped threads | |
3671 | @cindex threads, stopped | |
3672 | Whenever your program stops under @value{GDBN} for any reason, | |
3673 | @emph{all} threads of execution stop, not just the current thread. This | |
3674 | allows you to examine the overall state of the program, including | |
3675 | switching between threads, without worrying that things may change | |
3676 | underfoot. | |
3677 | ||
3678 | @cindex continuing threads | |
3679 | @cindex threads, continuing | |
3680 | Conversely, whenever you restart the program, @emph{all} threads start | |
3681 | executing. @emph{This is true even when single-stepping} with commands | |
5d161b24 | 3682 | like @code{step} or @code{next}. |
c906108c SS |
3683 | |
3684 | In particular, @value{GDBN} cannot single-step all threads in lockstep. | |
3685 | Since thread scheduling is up to your debugging target's operating | |
3686 | system (not controlled by @value{GDBN}), other threads may | |
3687 | execute more than one statement while the current thread completes a | |
3688 | single step. Moreover, in general other threads stop in the middle of a | |
3689 | statement, rather than at a clean statement boundary, when the program | |
3690 | stops. | |
3691 | ||
3692 | You might even find your program stopped in another thread after | |
3693 | continuing or even single-stepping. This happens whenever some other | |
3694 | thread runs into a breakpoint, a signal, or an exception before the | |
3695 | first thread completes whatever you requested. | |
3696 | ||
3697 | On some OSes, you can lock the OS scheduler and thus allow only a single | |
3698 | thread to run. | |
3699 | ||
3700 | @table @code | |
3701 | @item set scheduler-locking @var{mode} | |
3702 | Set the scheduler locking mode. If it is @code{off}, then there is no | |
3703 | locking and any thread may run at any time. If @code{on}, then only the | |
3704 | current thread may run when the inferior is resumed. The @code{step} | |
3705 | mode optimizes for single-stepping. It stops other threads from | |
3706 | ``seizing the prompt'' by preempting the current thread while you are | |
3707 | stepping. Other threads will only rarely (or never) get a chance to run | |
d4f3574e | 3708 | when you step. They are more likely to run when you @samp{next} over a |
c906108c | 3709 | function call, and they are completely free to run when you use commands |
d4f3574e | 3710 | like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another |
c906108c | 3711 | thread hits a breakpoint during its timeslice, they will never steal the |
2df3850c | 3712 | @value{GDBN} prompt away from the thread that you are debugging. |
c906108c SS |
3713 | |
3714 | @item show scheduler-locking | |
3715 | Display the current scheduler locking mode. | |
3716 | @end table | |
3717 | ||
c906108c | 3718 | |
6d2ebf8b | 3719 | @node Stack |
c906108c SS |
3720 | @chapter Examining the Stack |
3721 | ||
3722 | When your program has stopped, the first thing you need to know is where it | |
3723 | stopped and how it got there. | |
3724 | ||
3725 | @cindex call stack | |
5d161b24 DB |
3726 | Each time your program performs a function call, information about the call |
3727 | is generated. | |
3728 | That information includes the location of the call in your program, | |
3729 | the arguments of the call, | |
c906108c | 3730 | and the local variables of the function being called. |
5d161b24 | 3731 | The information is saved in a block of data called a @dfn{stack frame}. |
c906108c SS |
3732 | The stack frames are allocated in a region of memory called the @dfn{call |
3733 | stack}. | |
3734 | ||
3735 | When your program stops, the @value{GDBN} commands for examining the | |
3736 | stack allow you to see all of this information. | |
3737 | ||
3738 | @cindex selected frame | |
3739 | One of the stack frames is @dfn{selected} by @value{GDBN} and many | |
3740 | @value{GDBN} commands refer implicitly to the selected frame. In | |
3741 | particular, whenever you ask @value{GDBN} for the value of a variable in | |
3742 | your program, the value is found in the selected frame. There are | |
3743 | special @value{GDBN} commands to select whichever frame you are | |
3744 | interested in. @xref{Selection, ,Selecting a frame}. | |
3745 | ||
3746 | When your program stops, @value{GDBN} automatically selects the | |
5d161b24 | 3747 | currently executing frame and describes it briefly, similar to the |
c906108c SS |
3748 | @code{frame} command (@pxref{Frame Info, ,Information about a frame}). |
3749 | ||
3750 | @menu | |
3751 | * Frames:: Stack frames | |
3752 | * Backtrace:: Backtraces | |
3753 | * Selection:: Selecting a frame | |
3754 | * Frame Info:: Information on a frame | |
c906108c SS |
3755 | |
3756 | @end menu | |
3757 | ||
6d2ebf8b | 3758 | @node Frames |
c906108c SS |
3759 | @section Stack frames |
3760 | ||
d4f3574e | 3761 | @cindex frame, definition |
c906108c SS |
3762 | @cindex stack frame |
3763 | The call stack is divided up into contiguous pieces called @dfn{stack | |
3764 | frames}, or @dfn{frames} for short; each frame is the data associated | |
3765 | with one call to one function. The frame contains the arguments given | |
3766 | to the function, the function's local variables, and the address at | |
3767 | which the function is executing. | |
3768 | ||
3769 | @cindex initial frame | |
3770 | @cindex outermost frame | |
3771 | @cindex innermost frame | |
3772 | When your program is started, the stack has only one frame, that of the | |
3773 | function @code{main}. This is called the @dfn{initial} frame or the | |
3774 | @dfn{outermost} frame. Each time a function is called, a new frame is | |
3775 | made. Each time a function returns, the frame for that function invocation | |
3776 | is eliminated. If a function is recursive, there can be many frames for | |
3777 | the same function. The frame for the function in which execution is | |
3778 | actually occurring is called the @dfn{innermost} frame. This is the most | |
3779 | recently created of all the stack frames that still exist. | |
3780 | ||
3781 | @cindex frame pointer | |
3782 | Inside your program, stack frames are identified by their addresses. A | |
3783 | stack frame consists of many bytes, each of which has its own address; each | |
3784 | kind of computer has a convention for choosing one byte whose | |
3785 | address serves as the address of the frame. Usually this address is kept | |
3786 | in a register called the @dfn{frame pointer register} while execution is | |
3787 | going on in that frame. | |
3788 | ||
3789 | @cindex frame number | |
3790 | @value{GDBN} assigns numbers to all existing stack frames, starting with | |
3791 | zero for the innermost frame, one for the frame that called it, | |
3792 | and so on upward. These numbers do not really exist in your program; | |
3793 | they are assigned by @value{GDBN} to give you a way of designating stack | |
3794 | frames in @value{GDBN} commands. | |
3795 | ||
6d2ebf8b SS |
3796 | @c The -fomit-frame-pointer below perennially causes hbox overflow |
3797 | @c underflow problems. | |
c906108c SS |
3798 | @cindex frameless execution |
3799 | Some compilers provide a way to compile functions so that they operate | |
6d2ebf8b | 3800 | without stack frames. (For example, the @value{GCC} option |
474c8240 | 3801 | @smallexample |
6d2ebf8b | 3802 | @samp{-fomit-frame-pointer} |
474c8240 | 3803 | @end smallexample |
6d2ebf8b | 3804 | generates functions without a frame.) |
c906108c SS |
3805 | This is occasionally done with heavily used library functions to save |
3806 | the frame setup time. @value{GDBN} has limited facilities for dealing | |
3807 | with these function invocations. If the innermost function invocation | |
3808 | has no stack frame, @value{GDBN} nevertheless regards it as though | |
3809 | it had a separate frame, which is numbered zero as usual, allowing | |
3810 | correct tracing of the function call chain. However, @value{GDBN} has | |
3811 | no provision for frameless functions elsewhere in the stack. | |
3812 | ||
3813 | @table @code | |
d4f3574e | 3814 | @kindex frame@r{, command} |
41afff9a | 3815 | @cindex current stack frame |
c906108c | 3816 | @item frame @var{args} |
5d161b24 | 3817 | The @code{frame} command allows you to move from one stack frame to another, |
c906108c | 3818 | and to print the stack frame you select. @var{args} may be either the |
5d161b24 DB |
3819 | address of the frame or the stack frame number. Without an argument, |
3820 | @code{frame} prints the current stack frame. | |
c906108c SS |
3821 | |
3822 | @kindex select-frame | |
41afff9a | 3823 | @cindex selecting frame silently |
c906108c SS |
3824 | @item select-frame |
3825 | The @code{select-frame} command allows you to move from one stack frame | |
3826 | to another without printing the frame. This is the silent version of | |
3827 | @code{frame}. | |
3828 | @end table | |
3829 | ||
6d2ebf8b | 3830 | @node Backtrace |
c906108c SS |
3831 | @section Backtraces |
3832 | ||
3833 | @cindex backtraces | |
3834 | @cindex tracebacks | |
3835 | @cindex stack traces | |
3836 | A backtrace is a summary of how your program got where it is. It shows one | |
3837 | line per frame, for many frames, starting with the currently executing | |
3838 | frame (frame zero), followed by its caller (frame one), and on up the | |
3839 | stack. | |
3840 | ||
3841 | @table @code | |
3842 | @kindex backtrace | |
41afff9a | 3843 | @kindex bt @r{(@code{backtrace})} |
c906108c SS |
3844 | @item backtrace |
3845 | @itemx bt | |
3846 | Print a backtrace of the entire stack: one line per frame for all | |
3847 | frames in the stack. | |
3848 | ||
3849 | You can stop the backtrace at any time by typing the system interrupt | |
3850 | character, normally @kbd{C-c}. | |
3851 | ||
3852 | @item backtrace @var{n} | |
3853 | @itemx bt @var{n} | |
3854 | Similar, but print only the innermost @var{n} frames. | |
3855 | ||
3856 | @item backtrace -@var{n} | |
3857 | @itemx bt -@var{n} | |
3858 | Similar, but print only the outermost @var{n} frames. | |
3859 | @end table | |
3860 | ||
3861 | @kindex where | |
3862 | @kindex info stack | |
41afff9a | 3863 | @kindex info s @r{(@code{info stack})} |
c906108c SS |
3864 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) |
3865 | are additional aliases for @code{backtrace}. | |
3866 | ||
3867 | Each line in the backtrace shows the frame number and the function name. | |
3868 | The program counter value is also shown---unless you use @code{set | |
3869 | print address off}. The backtrace also shows the source file name and | |
3870 | line number, as well as the arguments to the function. The program | |
3871 | counter value is omitted if it is at the beginning of the code for that | |
3872 | line number. | |
3873 | ||
3874 | Here is an example of a backtrace. It was made with the command | |
3875 | @samp{bt 3}, so it shows the innermost three frames. | |
3876 | ||
3877 | @smallexample | |
3878 | @group | |
5d161b24 | 3879 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
c906108c SS |
3880 | at builtin.c:993 |
3881 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 | |
3882 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) | |
3883 | at macro.c:71 | |
3884 | (More stack frames follow...) | |
3885 | @end group | |
3886 | @end smallexample | |
3887 | ||
3888 | @noindent | |
3889 | The display for frame zero does not begin with a program counter | |
3890 | value, indicating that your program has stopped at the beginning of the | |
3891 | code for line @code{993} of @code{builtin.c}. | |
3892 | ||
b4e9345d DJ |
3893 | @kindex set backtrace-below-main |
3894 | @kindex show backtrace-below-main | |
3895 | ||
95f90d25 DJ |
3896 | Most programs have a standard entry point---a place where system libraries |
3897 | and startup code transition into user code. For C this is @code{main}. | |
3898 | When @value{GDBN} finds the entry function in a backtrace it will terminate | |
3899 | the backtrace, to avoid tracing into highly system-specific (and generally | |
3900 | uninteresting) code. If you need to examine the startup code, then you can | |
3901 | change this behavior. | |
3902 | ||
3903 | @table @code | |
3904 | @item set backtrace-below-main off | |
3905 | Backtraces will stop when they encounter the user entry point. This is the | |
3906 | default. | |
3907 | ||
3908 | @item set backtrace-below-main | |
3909 | @itemx set backtrace-below-main on | |
3910 | Backtraces will continue past the user entry point to the top of the stack. | |
3911 | ||
3912 | @item show backtrace-below-main | |
3913 | Display the current backtrace policy. | |
3914 | @end table | |
3915 | ||
6d2ebf8b | 3916 | @node Selection |
c906108c SS |
3917 | @section Selecting a frame |
3918 | ||
3919 | Most commands for examining the stack and other data in your program work on | |
3920 | whichever stack frame is selected at the moment. Here are the commands for | |
3921 | selecting a stack frame; all of them finish by printing a brief description | |
3922 | of the stack frame just selected. | |
3923 | ||
3924 | @table @code | |
d4f3574e | 3925 | @kindex frame@r{, selecting} |
41afff9a | 3926 | @kindex f @r{(@code{frame})} |
c906108c SS |
3927 | @item frame @var{n} |
3928 | @itemx f @var{n} | |
3929 | Select frame number @var{n}. Recall that frame zero is the innermost | |
3930 | (currently executing) frame, frame one is the frame that called the | |
3931 | innermost one, and so on. The highest-numbered frame is the one for | |
3932 | @code{main}. | |
3933 | ||
3934 | @item frame @var{addr} | |
3935 | @itemx f @var{addr} | |
3936 | Select the frame at address @var{addr}. This is useful mainly if the | |
3937 | chaining of stack frames has been damaged by a bug, making it | |
3938 | impossible for @value{GDBN} to assign numbers properly to all frames. In | |
3939 | addition, this can be useful when your program has multiple stacks and | |
3940 | switches between them. | |
3941 | ||
c906108c SS |
3942 | On the SPARC architecture, @code{frame} needs two addresses to |
3943 | select an arbitrary frame: a frame pointer and a stack pointer. | |
3944 | ||
3945 | On the MIPS and Alpha architecture, it needs two addresses: a stack | |
3946 | pointer and a program counter. | |
3947 | ||
3948 | On the 29k architecture, it needs three addresses: a register stack | |
3949 | pointer, a program counter, and a memory stack pointer. | |
3950 | @c note to future updaters: this is conditioned on a flag | |
3951 | @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date | |
3952 | @c as of 27 Jan 1994. | |
c906108c SS |
3953 | |
3954 | @kindex up | |
3955 | @item up @var{n} | |
3956 | Move @var{n} frames up the stack. For positive numbers @var{n}, this | |
3957 | advances toward the outermost frame, to higher frame numbers, to frames | |
3958 | that have existed longer. @var{n} defaults to one. | |
3959 | ||
3960 | @kindex down | |
41afff9a | 3961 | @kindex do @r{(@code{down})} |
c906108c SS |
3962 | @item down @var{n} |
3963 | Move @var{n} frames down the stack. For positive numbers @var{n}, this | |
3964 | advances toward the innermost frame, to lower frame numbers, to frames | |
3965 | that were created more recently. @var{n} defaults to one. You may | |
3966 | abbreviate @code{down} as @code{do}. | |
3967 | @end table | |
3968 | ||
3969 | All of these commands end by printing two lines of output describing the | |
3970 | frame. The first line shows the frame number, the function name, the | |
3971 | arguments, and the source file and line number of execution in that | |
5d161b24 | 3972 | frame. The second line shows the text of that source line. |
c906108c SS |
3973 | |
3974 | @need 1000 | |
3975 | For example: | |
3976 | ||
3977 | @smallexample | |
3978 | @group | |
3979 | (@value{GDBP}) up | |
3980 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) | |
3981 | at env.c:10 | |
3982 | 10 read_input_file (argv[i]); | |
3983 | @end group | |
3984 | @end smallexample | |
3985 | ||
3986 | After such a printout, the @code{list} command with no arguments | |
3987 | prints ten lines centered on the point of execution in the frame. | |
87885426 FN |
3988 | You can also edit the program at the point of execution with your favorite |
3989 | editing program by typing @code{edit}. | |
3990 | @xref{List, ,Printing source lines}, | |
3991 | for details. | |
c906108c SS |
3992 | |
3993 | @table @code | |
3994 | @kindex down-silently | |
3995 | @kindex up-silently | |
3996 | @item up-silently @var{n} | |
3997 | @itemx down-silently @var{n} | |
3998 | These two commands are variants of @code{up} and @code{down}, | |
3999 | respectively; they differ in that they do their work silently, without | |
4000 | causing display of the new frame. They are intended primarily for use | |
4001 | in @value{GDBN} command scripts, where the output might be unnecessary and | |
4002 | distracting. | |
4003 | @end table | |
4004 | ||
6d2ebf8b | 4005 | @node Frame Info |
c906108c SS |
4006 | @section Information about a frame |
4007 | ||
4008 | There are several other commands to print information about the selected | |
4009 | stack frame. | |
4010 | ||
4011 | @table @code | |
4012 | @item frame | |
4013 | @itemx f | |
4014 | When used without any argument, this command does not change which | |
4015 | frame is selected, but prints a brief description of the currently | |
4016 | selected stack frame. It can be abbreviated @code{f}. With an | |
4017 | argument, this command is used to select a stack frame. | |
4018 | @xref{Selection, ,Selecting a frame}. | |
4019 | ||
4020 | @kindex info frame | |
41afff9a | 4021 | @kindex info f @r{(@code{info frame})} |
c906108c SS |
4022 | @item info frame |
4023 | @itemx info f | |
4024 | This command prints a verbose description of the selected stack frame, | |
4025 | including: | |
4026 | ||
4027 | @itemize @bullet | |
5d161b24 DB |
4028 | @item |
4029 | the address of the frame | |
c906108c SS |
4030 | @item |
4031 | the address of the next frame down (called by this frame) | |
4032 | @item | |
4033 | the address of the next frame up (caller of this frame) | |
4034 | @item | |
4035 | the language in which the source code corresponding to this frame is written | |
4036 | @item | |
4037 | the address of the frame's arguments | |
4038 | @item | |
d4f3574e SS |
4039 | the address of the frame's local variables |
4040 | @item | |
c906108c SS |
4041 | the program counter saved in it (the address of execution in the caller frame) |
4042 | @item | |
4043 | which registers were saved in the frame | |
4044 | @end itemize | |
4045 | ||
4046 | @noindent The verbose description is useful when | |
4047 | something has gone wrong that has made the stack format fail to fit | |
4048 | the usual conventions. | |
4049 | ||
4050 | @item info frame @var{addr} | |
4051 | @itemx info f @var{addr} | |
4052 | Print a verbose description of the frame at address @var{addr}, without | |
4053 | selecting that frame. The selected frame remains unchanged by this | |
4054 | command. This requires the same kind of address (more than one for some | |
4055 | architectures) that you specify in the @code{frame} command. | |
4056 | @xref{Selection, ,Selecting a frame}. | |
4057 | ||
4058 | @kindex info args | |
4059 | @item info args | |
4060 | Print the arguments of the selected frame, each on a separate line. | |
4061 | ||
4062 | @item info locals | |
4063 | @kindex info locals | |
4064 | Print the local variables of the selected frame, each on a separate | |
4065 | line. These are all variables (declared either static or automatic) | |
4066 | accessible at the point of execution of the selected frame. | |
4067 | ||
c906108c | 4068 | @kindex info catch |
d4f3574e SS |
4069 | @cindex catch exceptions, list active handlers |
4070 | @cindex exception handlers, how to list | |
c906108c SS |
4071 | @item info catch |
4072 | Print a list of all the exception handlers that are active in the | |
4073 | current stack frame at the current point of execution. To see other | |
4074 | exception handlers, visit the associated frame (using the @code{up}, | |
4075 | @code{down}, or @code{frame} commands); then type @code{info catch}. | |
4076 | @xref{Set Catchpoints, , Setting catchpoints}. | |
53a5351d | 4077 | |
c906108c SS |
4078 | @end table |
4079 | ||
c906108c | 4080 | |
6d2ebf8b | 4081 | @node Source |
c906108c SS |
4082 | @chapter Examining Source Files |
4083 | ||
4084 | @value{GDBN} can print parts of your program's source, since the debugging | |
4085 | information recorded in the program tells @value{GDBN} what source files were | |
4086 | used to build it. When your program stops, @value{GDBN} spontaneously prints | |
4087 | the line where it stopped. Likewise, when you select a stack frame | |
4088 | (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where | |
4089 | execution in that frame has stopped. You can print other portions of | |
4090 | source files by explicit command. | |
4091 | ||
7a292a7a | 4092 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may |
d4f3574e | 4093 | prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using |
7a292a7a | 4094 | @value{GDBN} under @sc{gnu} Emacs}. |
c906108c SS |
4095 | |
4096 | @menu | |
4097 | * List:: Printing source lines | |
87885426 | 4098 | * Edit:: Editing source files |
c906108c | 4099 | * Search:: Searching source files |
c906108c SS |
4100 | * Source Path:: Specifying source directories |
4101 | * Machine Code:: Source and machine code | |
4102 | @end menu | |
4103 | ||
6d2ebf8b | 4104 | @node List |
c906108c SS |
4105 | @section Printing source lines |
4106 | ||
4107 | @kindex list | |
41afff9a | 4108 | @kindex l @r{(@code{list})} |
c906108c | 4109 | To print lines from a source file, use the @code{list} command |
5d161b24 | 4110 | (abbreviated @code{l}). By default, ten lines are printed. |
c906108c SS |
4111 | There are several ways to specify what part of the file you want to print. |
4112 | ||
4113 | Here are the forms of the @code{list} command most commonly used: | |
4114 | ||
4115 | @table @code | |
4116 | @item list @var{linenum} | |
4117 | Print lines centered around line number @var{linenum} in the | |
4118 | current source file. | |
4119 | ||
4120 | @item list @var{function} | |
4121 | Print lines centered around the beginning of function | |
4122 | @var{function}. | |
4123 | ||
4124 | @item list | |
4125 | Print more lines. If the last lines printed were printed with a | |
4126 | @code{list} command, this prints lines following the last lines | |
4127 | printed; however, if the last line printed was a solitary line printed | |
4128 | as part of displaying a stack frame (@pxref{Stack, ,Examining the | |
4129 | Stack}), this prints lines centered around that line. | |
4130 | ||
4131 | @item list - | |
4132 | Print lines just before the lines last printed. | |
4133 | @end table | |
4134 | ||
4135 | By default, @value{GDBN} prints ten source lines with any of these forms of | |
4136 | the @code{list} command. You can change this using @code{set listsize}: | |
4137 | ||
4138 | @table @code | |
4139 | @kindex set listsize | |
4140 | @item set listsize @var{count} | |
4141 | Make the @code{list} command display @var{count} source lines (unless | |
4142 | the @code{list} argument explicitly specifies some other number). | |
4143 | ||
4144 | @kindex show listsize | |
4145 | @item show listsize | |
4146 | Display the number of lines that @code{list} prints. | |
4147 | @end table | |
4148 | ||
4149 | Repeating a @code{list} command with @key{RET} discards the argument, | |
4150 | so it is equivalent to typing just @code{list}. This is more useful | |
4151 | than listing the same lines again. An exception is made for an | |
4152 | argument of @samp{-}; that argument is preserved in repetition so that | |
4153 | each repetition moves up in the source file. | |
4154 | ||
4155 | @cindex linespec | |
4156 | In general, the @code{list} command expects you to supply zero, one or two | |
4157 | @dfn{linespecs}. Linespecs specify source lines; there are several ways | |
d4f3574e | 4158 | of writing them, but the effect is always to specify some source line. |
c906108c SS |
4159 | Here is a complete description of the possible arguments for @code{list}: |
4160 | ||
4161 | @table @code | |
4162 | @item list @var{linespec} | |
4163 | Print lines centered around the line specified by @var{linespec}. | |
4164 | ||
4165 | @item list @var{first},@var{last} | |
4166 | Print lines from @var{first} to @var{last}. Both arguments are | |
4167 | linespecs. | |
4168 | ||
4169 | @item list ,@var{last} | |
4170 | Print lines ending with @var{last}. | |
4171 | ||
4172 | @item list @var{first}, | |
4173 | Print lines starting with @var{first}. | |
4174 | ||
4175 | @item list + | |
4176 | Print lines just after the lines last printed. | |
4177 | ||
4178 | @item list - | |
4179 | Print lines just before the lines last printed. | |
4180 | ||
4181 | @item list | |
4182 | As described in the preceding table. | |
4183 | @end table | |
4184 | ||
4185 | Here are the ways of specifying a single source line---all the | |
4186 | kinds of linespec. | |
4187 | ||
4188 | @table @code | |
4189 | @item @var{number} | |
4190 | Specifies line @var{number} of the current source file. | |
4191 | When a @code{list} command has two linespecs, this refers to | |
4192 | the same source file as the first linespec. | |
4193 | ||
4194 | @item +@var{offset} | |
4195 | Specifies the line @var{offset} lines after the last line printed. | |
4196 | When used as the second linespec in a @code{list} command that has | |
4197 | two, this specifies the line @var{offset} lines down from the | |
4198 | first linespec. | |
4199 | ||
4200 | @item -@var{offset} | |
4201 | Specifies the line @var{offset} lines before the last line printed. | |
4202 | ||
4203 | @item @var{filename}:@var{number} | |
4204 | Specifies line @var{number} in the source file @var{filename}. | |
4205 | ||
4206 | @item @var{function} | |
4207 | Specifies the line that begins the body of the function @var{function}. | |
4208 | For example: in C, this is the line with the open brace. | |
4209 | ||
4210 | @item @var{filename}:@var{function} | |
4211 | Specifies the line of the open-brace that begins the body of the | |
4212 | function @var{function} in the file @var{filename}. You only need the | |
4213 | file name with a function name to avoid ambiguity when there are | |
4214 | identically named functions in different source files. | |
4215 | ||
4216 | @item *@var{address} | |
4217 | Specifies the line containing the program address @var{address}. | |
4218 | @var{address} may be any expression. | |
4219 | @end table | |
4220 | ||
87885426 FN |
4221 | @node Edit |
4222 | @section Editing source files | |
4223 | @cindex editing source files | |
4224 | ||
4225 | @kindex edit | |
4226 | @kindex e @r{(@code{edit})} | |
4227 | To edit the lines in a source file, use the @code{edit} command. | |
4228 | The editing program of your choice | |
4229 | is invoked with the current line set to | |
4230 | the active line in the program. | |
4231 | Alternatively, there are several ways to specify what part of the file you | |
4232 | want to print if you want to see other parts of the program. | |
4233 | ||
4234 | Here are the forms of the @code{edit} command most commonly used: | |
4235 | ||
4236 | @table @code | |
4237 | @item edit | |
4238 | Edit the current source file at the active line number in the program. | |
4239 | ||
4240 | @item edit @var{number} | |
4241 | Edit the current source file with @var{number} as the active line number. | |
4242 | ||
4243 | @item edit @var{function} | |
4244 | Edit the file containing @var{function} at the beginning of its definition. | |
4245 | ||
4246 | @item edit @var{filename}:@var{number} | |
4247 | Specifies line @var{number} in the source file @var{filename}. | |
4248 | ||
4249 | @item edit @var{filename}:@var{function} | |
4250 | Specifies the line that begins the body of the | |
4251 | function @var{function} in the file @var{filename}. You only need the | |
4252 | file name with a function name to avoid ambiguity when there are | |
4253 | identically named functions in different source files. | |
4254 | ||
4255 | @item edit *@var{address} | |
4256 | Specifies the line containing the program address @var{address}. | |
4257 | @var{address} may be any expression. | |
4258 | @end table | |
4259 | ||
4260 | @subsection Choosing your editor | |
4261 | You can customize @value{GDBN} to use any editor you want | |
4262 | @footnote{ | |
4263 | The only restriction is that your editor (say @code{ex}), recognizes the | |
4264 | following command-line syntax: | |
10998722 | 4265 | @smallexample |
87885426 | 4266 | ex +@var{number} file |
10998722 AC |
4267 | @end smallexample |
4268 | The optional numeric value +@var{number} designates the active line in | |
4269 | the file.}. By default, it is @value{EDITOR}, but you can change this | |
4270 | by setting the environment variable @code{EDITOR} before using | |
4271 | @value{GDBN}. For example, to configure @value{GDBN} to use the | |
4272 | @code{vi} editor, you could use these commands with the @code{sh} shell: | |
4273 | @smallexample | |
87885426 FN |
4274 | EDITOR=/usr/bin/vi |
4275 | export EDITOR | |
4276 | gdb ... | |
10998722 | 4277 | @end smallexample |
87885426 | 4278 | or in the @code{csh} shell, |
10998722 | 4279 | @smallexample |
87885426 FN |
4280 | setenv EDITOR /usr/bin/vi |
4281 | gdb ... | |
10998722 | 4282 | @end smallexample |
87885426 | 4283 | |
6d2ebf8b | 4284 | @node Search |
c906108c SS |
4285 | @section Searching source files |
4286 | @cindex searching | |
4287 | @kindex reverse-search | |
4288 | ||
4289 | There are two commands for searching through the current source file for a | |
4290 | regular expression. | |
4291 | ||
4292 | @table @code | |
4293 | @kindex search | |
4294 | @kindex forward-search | |
4295 | @item forward-search @var{regexp} | |
4296 | @itemx search @var{regexp} | |
4297 | The command @samp{forward-search @var{regexp}} checks each line, | |
4298 | starting with the one following the last line listed, for a match for | |
5d161b24 | 4299 | @var{regexp}. It lists the line that is found. You can use the |
c906108c SS |
4300 | synonym @samp{search @var{regexp}} or abbreviate the command name as |
4301 | @code{fo}. | |
4302 | ||
4303 | @item reverse-search @var{regexp} | |
4304 | The command @samp{reverse-search @var{regexp}} checks each line, starting | |
4305 | with the one before the last line listed and going backward, for a match | |
4306 | for @var{regexp}. It lists the line that is found. You can abbreviate | |
4307 | this command as @code{rev}. | |
4308 | @end table | |
c906108c | 4309 | |
6d2ebf8b | 4310 | @node Source Path |
c906108c SS |
4311 | @section Specifying source directories |
4312 | ||
4313 | @cindex source path | |
4314 | @cindex directories for source files | |
4315 | Executable programs sometimes do not record the directories of the source | |
4316 | files from which they were compiled, just the names. Even when they do, | |
4317 | the directories could be moved between the compilation and your debugging | |
4318 | session. @value{GDBN} has a list of directories to search for source files; | |
4319 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, | |
4320 | it tries all the directories in the list, in the order they are present | |
4321 | in the list, until it finds a file with the desired name. Note that | |
4322 | the executable search path is @emph{not} used for this purpose. Neither is | |
4323 | the current working directory, unless it happens to be in the source | |
4324 | path. | |
4325 | ||
4326 | If @value{GDBN} cannot find a source file in the source path, and the | |
4327 | object program records a directory, @value{GDBN} tries that directory | |
4328 | too. If the source path is empty, and there is no record of the | |
4329 | compilation directory, @value{GDBN} looks in the current directory as a | |
4330 | last resort. | |
4331 | ||
4332 | Whenever you reset or rearrange the source path, @value{GDBN} clears out | |
4333 | any information it has cached about where source files are found and where | |
4334 | each line is in the file. | |
4335 | ||
4336 | @kindex directory | |
4337 | @kindex dir | |
d4f3574e SS |
4338 | When you start @value{GDBN}, its source path includes only @samp{cdir} |
4339 | and @samp{cwd}, in that order. | |
c906108c SS |
4340 | To add other directories, use the @code{directory} command. |
4341 | ||
4342 | @table @code | |
4343 | @item directory @var{dirname} @dots{} | |
4344 | @item dir @var{dirname} @dots{} | |
4345 | Add directory @var{dirname} to the front of the source path. Several | |
d4f3574e SS |
4346 | directory names may be given to this command, separated by @samp{:} |
4347 | (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as | |
4348 | part of absolute file names) or | |
c906108c SS |
4349 | whitespace. You may specify a directory that is already in the source |
4350 | path; this moves it forward, so @value{GDBN} searches it sooner. | |
4351 | ||
4352 | @kindex cdir | |
4353 | @kindex cwd | |
41afff9a EZ |
4354 | @vindex $cdir@r{, convenience variable} |
4355 | @vindex $cwdr@r{, convenience variable} | |
c906108c SS |
4356 | @cindex compilation directory |
4357 | @cindex current directory | |
4358 | @cindex working directory | |
4359 | @cindex directory, current | |
4360 | @cindex directory, compilation | |
4361 | You can use the string @samp{$cdir} to refer to the compilation | |
4362 | directory (if one is recorded), and @samp{$cwd} to refer to the current | |
4363 | working directory. @samp{$cwd} is not the same as @samp{.}---the former | |
4364 | tracks the current working directory as it changes during your @value{GDBN} | |
4365 | session, while the latter is immediately expanded to the current | |
4366 | directory at the time you add an entry to the source path. | |
4367 | ||
4368 | @item directory | |
4369 | Reset the source path to empty again. This requires confirmation. | |
4370 | ||
4371 | @c RET-repeat for @code{directory} is explicitly disabled, but since | |
4372 | @c repeating it would be a no-op we do not say that. (thanks to RMS) | |
4373 | ||
4374 | @item show directories | |
4375 | @kindex show directories | |
4376 | Print the source path: show which directories it contains. | |
4377 | @end table | |
4378 | ||
4379 | If your source path is cluttered with directories that are no longer of | |
4380 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong | |
4381 | versions of source. You can correct the situation as follows: | |
4382 | ||
4383 | @enumerate | |
4384 | @item | |
4385 | Use @code{directory} with no argument to reset the source path to empty. | |
4386 | ||
4387 | @item | |
4388 | Use @code{directory} with suitable arguments to reinstall the | |
4389 | directories you want in the source path. You can add all the | |
4390 | directories in one command. | |
4391 | @end enumerate | |
4392 | ||
6d2ebf8b | 4393 | @node Machine Code |
c906108c SS |
4394 | @section Source and machine code |
4395 | ||
4396 | You can use the command @code{info line} to map source lines to program | |
4397 | addresses (and vice versa), and the command @code{disassemble} to display | |
4398 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs | |
d4f3574e | 4399 | mode, the @code{info line} command causes the arrow to point to the |
5d161b24 | 4400 | line specified. Also, @code{info line} prints addresses in symbolic form as |
c906108c SS |
4401 | well as hex. |
4402 | ||
4403 | @table @code | |
4404 | @kindex info line | |
4405 | @item info line @var{linespec} | |
4406 | Print the starting and ending addresses of the compiled code for | |
4407 | source line @var{linespec}. You can specify source lines in any of | |
4408 | the ways understood by the @code{list} command (@pxref{List, ,Printing | |
4409 | source lines}). | |
4410 | @end table | |
4411 | ||
4412 | For example, we can use @code{info line} to discover the location of | |
4413 | the object code for the first line of function | |
4414 | @code{m4_changequote}: | |
4415 | ||
d4f3574e SS |
4416 | @c FIXME: I think this example should also show the addresses in |
4417 | @c symbolic form, as they usually would be displayed. | |
c906108c | 4418 | @smallexample |
96a2c332 | 4419 | (@value{GDBP}) info line m4_changequote |
c906108c SS |
4420 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. |
4421 | @end smallexample | |
4422 | ||
4423 | @noindent | |
4424 | We can also inquire (using @code{*@var{addr}} as the form for | |
4425 | @var{linespec}) what source line covers a particular address: | |
4426 | @smallexample | |
4427 | (@value{GDBP}) info line *0x63ff | |
4428 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. | |
4429 | @end smallexample | |
4430 | ||
4431 | @cindex @code{$_} and @code{info line} | |
41afff9a | 4432 | @kindex x@r{(examine), and} info line |
c906108c SS |
4433 | After @code{info line}, the default address for the @code{x} command |
4434 | is changed to the starting address of the line, so that @samp{x/i} is | |
4435 | sufficient to begin examining the machine code (@pxref{Memory, | |
4436 | ,Examining memory}). Also, this address is saved as the value of the | |
4437 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience | |
4438 | variables}). | |
4439 | ||
4440 | @table @code | |
4441 | @kindex disassemble | |
4442 | @cindex assembly instructions | |
4443 | @cindex instructions, assembly | |
4444 | @cindex machine instructions | |
4445 | @cindex listing machine instructions | |
4446 | @item disassemble | |
4447 | This specialized command dumps a range of memory as machine | |
4448 | instructions. The default memory range is the function surrounding the | |
4449 | program counter of the selected frame. A single argument to this | |
4450 | command is a program counter value; @value{GDBN} dumps the function | |
4451 | surrounding this value. Two arguments specify a range of addresses | |
4452 | (first inclusive, second exclusive) to dump. | |
4453 | @end table | |
4454 | ||
c906108c SS |
4455 | The following example shows the disassembly of a range of addresses of |
4456 | HP PA-RISC 2.0 code: | |
4457 | ||
4458 | @smallexample | |
4459 | (@value{GDBP}) disas 0x32c4 0x32e4 | |
4460 | Dump of assembler code from 0x32c4 to 0x32e4: | |
4461 | 0x32c4 <main+204>: addil 0,dp | |
4462 | 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 | |
4463 | 0x32cc <main+212>: ldil 0x3000,r31 | |
4464 | 0x32d0 <main+216>: ble 0x3f8(sr4,r31) | |
4465 | 0x32d4 <main+220>: ldo 0(r31),rp | |
4466 | 0x32d8 <main+224>: addil -0x800,dp | |
4467 | 0x32dc <main+228>: ldo 0x588(r1),r26 | |
4468 | 0x32e0 <main+232>: ldil 0x3000,r31 | |
4469 | End of assembler dump. | |
4470 | @end smallexample | |
c906108c SS |
4471 | |
4472 | Some architectures have more than one commonly-used set of instruction | |
4473 | mnemonics or other syntax. | |
4474 | ||
4475 | @table @code | |
d4f3574e | 4476 | @kindex set disassembly-flavor |
c906108c SS |
4477 | @cindex assembly instructions |
4478 | @cindex instructions, assembly | |
4479 | @cindex machine instructions | |
4480 | @cindex listing machine instructions | |
d4f3574e SS |
4481 | @cindex Intel disassembly flavor |
4482 | @cindex AT&T disassembly flavor | |
4483 | @item set disassembly-flavor @var{instruction-set} | |
c906108c SS |
4484 | Select the instruction set to use when disassembling the |
4485 | program via the @code{disassemble} or @code{x/i} commands. | |
4486 | ||
4487 | Currently this command is only defined for the Intel x86 family. You | |
d4f3574e SS |
4488 | can set @var{instruction-set} to either @code{intel} or @code{att}. |
4489 | The default is @code{att}, the AT&T flavor used by default by Unix | |
4490 | assemblers for x86-based targets. | |
c906108c SS |
4491 | @end table |
4492 | ||
4493 | ||
6d2ebf8b | 4494 | @node Data |
c906108c SS |
4495 | @chapter Examining Data |
4496 | ||
4497 | @cindex printing data | |
4498 | @cindex examining data | |
4499 | @kindex print | |
4500 | @kindex inspect | |
4501 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not | |
4502 | @c document because it is nonstandard... Under Epoch it displays in a | |
4503 | @c different window or something like that. | |
4504 | The usual way to examine data in your program is with the @code{print} | |
7a292a7a SS |
4505 | command (abbreviated @code{p}), or its synonym @code{inspect}. It |
4506 | evaluates and prints the value of an expression of the language your | |
4507 | program is written in (@pxref{Languages, ,Using @value{GDBN} with | |
4508 | Different Languages}). | |
c906108c SS |
4509 | |
4510 | @table @code | |
d4f3574e SS |
4511 | @item print @var{expr} |
4512 | @itemx print /@var{f} @var{expr} | |
4513 | @var{expr} is an expression (in the source language). By default the | |
4514 | value of @var{expr} is printed in a format appropriate to its data type; | |
c906108c | 4515 | you can choose a different format by specifying @samp{/@var{f}}, where |
d4f3574e | 4516 | @var{f} is a letter specifying the format; see @ref{Output Formats,,Output |
c906108c SS |
4517 | formats}. |
4518 | ||
4519 | @item print | |
4520 | @itemx print /@var{f} | |
d4f3574e | 4521 | If you omit @var{expr}, @value{GDBN} displays the last value again (from the |
c906108c SS |
4522 | @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to |
4523 | conveniently inspect the same value in an alternative format. | |
4524 | @end table | |
4525 | ||
4526 | A more low-level way of examining data is with the @code{x} command. | |
4527 | It examines data in memory at a specified address and prints it in a | |
4528 | specified format. @xref{Memory, ,Examining memory}. | |
4529 | ||
7a292a7a | 4530 | If you are interested in information about types, or about how the |
d4f3574e SS |
4531 | fields of a struct or a class are declared, use the @code{ptype @var{exp}} |
4532 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol | |
7a292a7a | 4533 | Table}. |
c906108c SS |
4534 | |
4535 | @menu | |
4536 | * Expressions:: Expressions | |
4537 | * Variables:: Program variables | |
4538 | * Arrays:: Artificial arrays | |
4539 | * Output Formats:: Output formats | |
4540 | * Memory:: Examining memory | |
4541 | * Auto Display:: Automatic display | |
4542 | * Print Settings:: Print settings | |
4543 | * Value History:: Value history | |
4544 | * Convenience Vars:: Convenience variables | |
4545 | * Registers:: Registers | |
c906108c | 4546 | * Floating Point Hardware:: Floating point hardware |
53c69bd7 | 4547 | * Vector Unit:: Vector Unit |
29e57380 | 4548 | * Memory Region Attributes:: Memory region attributes |
16d9dec6 | 4549 | * Dump/Restore Files:: Copy between memory and a file |
a0eb71c5 KB |
4550 | * Character Sets:: Debugging programs that use a different |
4551 | character set than GDB does | |
c906108c SS |
4552 | @end menu |
4553 | ||
6d2ebf8b | 4554 | @node Expressions |
c906108c SS |
4555 | @section Expressions |
4556 | ||
4557 | @cindex expressions | |
4558 | @code{print} and many other @value{GDBN} commands accept an expression and | |
4559 | compute its value. Any kind of constant, variable or operator defined | |
4560 | by the programming language you are using is valid in an expression in | |
e2e0bcd1 JB |
4561 | @value{GDBN}. This includes conditional expressions, function calls, |
4562 | casts, and string constants. It also includes preprocessor macros, if | |
4563 | you compiled your program to include this information; see | |
4564 | @ref{Compilation}. | |
c906108c | 4565 | |
d4f3574e SS |
4566 | @value{GDBN} supports array constants in expressions input by |
4567 | the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example, | |
5d161b24 | 4568 | you can use the command @code{print @{1, 2, 3@}} to build up an array in |
d4f3574e | 4569 | memory that is @code{malloc}ed in the target program. |
c906108c | 4570 | |
c906108c SS |
4571 | Because C is so widespread, most of the expressions shown in examples in |
4572 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different | |
4573 | Languages}, for information on how to use expressions in other | |
4574 | languages. | |
4575 | ||
4576 | In this section, we discuss operators that you can use in @value{GDBN} | |
4577 | expressions regardless of your programming language. | |
4578 | ||
4579 | Casts are supported in all languages, not just in C, because it is so | |
4580 | useful to cast a number into a pointer in order to examine a structure | |
4581 | at that address in memory. | |
4582 | @c FIXME: casts supported---Mod2 true? | |
c906108c SS |
4583 | |
4584 | @value{GDBN} supports these operators, in addition to those common | |
4585 | to programming languages: | |
4586 | ||
4587 | @table @code | |
4588 | @item @@ | |
4589 | @samp{@@} is a binary operator for treating parts of memory as arrays. | |
4590 | @xref{Arrays, ,Artificial arrays}, for more information. | |
4591 | ||
4592 | @item :: | |
4593 | @samp{::} allows you to specify a variable in terms of the file or | |
4594 | function where it is defined. @xref{Variables, ,Program variables}. | |
4595 | ||
4596 | @cindex @{@var{type}@} | |
4597 | @cindex type casting memory | |
4598 | @cindex memory, viewing as typed object | |
4599 | @cindex casts, to view memory | |
4600 | @item @{@var{type}@} @var{addr} | |
4601 | Refers to an object of type @var{type} stored at address @var{addr} in | |
4602 | memory. @var{addr} may be any expression whose value is an integer or | |
4603 | pointer (but parentheses are required around binary operators, just as in | |
4604 | a cast). This construct is allowed regardless of what kind of data is | |
4605 | normally supposed to reside at @var{addr}. | |
4606 | @end table | |
4607 | ||
6d2ebf8b | 4608 | @node Variables |
c906108c SS |
4609 | @section Program variables |
4610 | ||
4611 | The most common kind of expression to use is the name of a variable | |
4612 | in your program. | |
4613 | ||
4614 | Variables in expressions are understood in the selected stack frame | |
4615 | (@pxref{Selection, ,Selecting a frame}); they must be either: | |
4616 | ||
4617 | @itemize @bullet | |
4618 | @item | |
4619 | global (or file-static) | |
4620 | @end itemize | |
4621 | ||
5d161b24 | 4622 | @noindent or |
c906108c SS |
4623 | |
4624 | @itemize @bullet | |
4625 | @item | |
4626 | visible according to the scope rules of the | |
4627 | programming language from the point of execution in that frame | |
5d161b24 | 4628 | @end itemize |
c906108c SS |
4629 | |
4630 | @noindent This means that in the function | |
4631 | ||
474c8240 | 4632 | @smallexample |
c906108c SS |
4633 | foo (a) |
4634 | int a; | |
4635 | @{ | |
4636 | bar (a); | |
4637 | @{ | |
4638 | int b = test (); | |
4639 | bar (b); | |
4640 | @} | |
4641 | @} | |
474c8240 | 4642 | @end smallexample |
c906108c SS |
4643 | |
4644 | @noindent | |
4645 | you can examine and use the variable @code{a} whenever your program is | |
4646 | executing within the function @code{foo}, but you can only use or | |
4647 | examine the variable @code{b} while your program is executing inside | |
4648 | the block where @code{b} is declared. | |
4649 | ||
4650 | @cindex variable name conflict | |
4651 | There is an exception: you can refer to a variable or function whose | |
4652 | scope is a single source file even if the current execution point is not | |
4653 | in this file. But it is possible to have more than one such variable or | |
4654 | function with the same name (in different source files). If that | |
4655 | happens, referring to that name has unpredictable effects. If you wish, | |
4656 | you can specify a static variable in a particular function or file, | |
4657 | using the colon-colon notation: | |
4658 | ||
d4f3574e | 4659 | @cindex colon-colon, context for variables/functions |
c906108c SS |
4660 | @iftex |
4661 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? | |
41afff9a | 4662 | @cindex @code{::}, context for variables/functions |
c906108c | 4663 | @end iftex |
474c8240 | 4664 | @smallexample |
c906108c SS |
4665 | @var{file}::@var{variable} |
4666 | @var{function}::@var{variable} | |
474c8240 | 4667 | @end smallexample |
c906108c SS |
4668 | |
4669 | @noindent | |
4670 | Here @var{file} or @var{function} is the name of the context for the | |
4671 | static @var{variable}. In the case of file names, you can use quotes to | |
4672 | make sure @value{GDBN} parses the file name as a single word---for example, | |
4673 | to print a global value of @code{x} defined in @file{f2.c}: | |
4674 | ||
474c8240 | 4675 | @smallexample |
c906108c | 4676 | (@value{GDBP}) p 'f2.c'::x |
474c8240 | 4677 | @end smallexample |
c906108c | 4678 | |
b37052ae | 4679 | @cindex C@t{++} scope resolution |
c906108c | 4680 | This use of @samp{::} is very rarely in conflict with the very similar |
b37052ae | 4681 | use of the same notation in C@t{++}. @value{GDBN} also supports use of the C@t{++} |
c906108c SS |
4682 | scope resolution operator in @value{GDBN} expressions. |
4683 | @c FIXME: Um, so what happens in one of those rare cases where it's in | |
4684 | @c conflict?? --mew | |
c906108c SS |
4685 | |
4686 | @cindex wrong values | |
4687 | @cindex variable values, wrong | |
4688 | @quotation | |
4689 | @emph{Warning:} Occasionally, a local variable may appear to have the | |
4690 | wrong value at certain points in a function---just after entry to a new | |
4691 | scope, and just before exit. | |
4692 | @end quotation | |
4693 | You may see this problem when you are stepping by machine instructions. | |
4694 | This is because, on most machines, it takes more than one instruction to | |
4695 | set up a stack frame (including local variable definitions); if you are | |
4696 | stepping by machine instructions, variables may appear to have the wrong | |
4697 | values until the stack frame is completely built. On exit, it usually | |
4698 | also takes more than one machine instruction to destroy a stack frame; | |
4699 | after you begin stepping through that group of instructions, local | |
4700 | variable definitions may be gone. | |
4701 | ||
4702 | This may also happen when the compiler does significant optimizations. | |
4703 | To be sure of always seeing accurate values, turn off all optimization | |
4704 | when compiling. | |
4705 | ||
d4f3574e SS |
4706 | @cindex ``No symbol "foo" in current context'' |
4707 | Another possible effect of compiler optimizations is to optimize | |
4708 | unused variables out of existence, or assign variables to registers (as | |
4709 | opposed to memory addresses). Depending on the support for such cases | |
4710 | offered by the debug info format used by the compiler, @value{GDBN} | |
4711 | might not be able to display values for such local variables. If that | |
4712 | happens, @value{GDBN} will print a message like this: | |
4713 | ||
474c8240 | 4714 | @smallexample |
d4f3574e | 4715 | No symbol "foo" in current context. |
474c8240 | 4716 | @end smallexample |
d4f3574e SS |
4717 | |
4718 | To solve such problems, either recompile without optimizations, or use a | |
4719 | different debug info format, if the compiler supports several such | |
0179ffac DC |
4720 | formats. For example, @value{NGCC}, the @sc{gnu} C/C@t{++} compiler |
4721 | usually supports the @option{-gstabs+} option. @option{-gstabs+} | |
4722 | produces debug info in a format that is superior to formats such as | |
4723 | COFF. You may be able to use DWARF 2 (@option{-gdwarf-2}), which is also | |
4724 | an effective form for debug info. @xref{Debugging Options,,Options | |
4725 | for Debugging Your Program or @sc{gnu} CC, gcc.info, Using @sc{gnu} CC}. | |
d4f3574e SS |
4726 | |
4727 | ||
6d2ebf8b | 4728 | @node Arrays |
c906108c SS |
4729 | @section Artificial arrays |
4730 | ||
4731 | @cindex artificial array | |
41afff9a | 4732 | @kindex @@@r{, referencing memory as an array} |
c906108c SS |
4733 | It is often useful to print out several successive objects of the |
4734 | same type in memory; a section of an array, or an array of | |
4735 | dynamically determined size for which only a pointer exists in the | |
4736 | program. | |
4737 | ||
4738 | You can do this by referring to a contiguous span of memory as an | |
4739 | @dfn{artificial array}, using the binary operator @samp{@@}. The left | |
4740 | operand of @samp{@@} should be the first element of the desired array | |
4741 | and be an individual object. The right operand should be the desired length | |
4742 | of the array. The result is an array value whose elements are all of | |
4743 | the type of the left argument. The first element is actually the left | |
4744 | argument; the second element comes from bytes of memory immediately | |
4745 | following those that hold the first element, and so on. Here is an | |
4746 | example. If a program says | |
4747 | ||
474c8240 | 4748 | @smallexample |
c906108c | 4749 | int *array = (int *) malloc (len * sizeof (int)); |
474c8240 | 4750 | @end smallexample |
c906108c SS |
4751 | |
4752 | @noindent | |
4753 | you can print the contents of @code{array} with | |
4754 | ||
474c8240 | 4755 | @smallexample |
c906108c | 4756 | p *array@@len |
474c8240 | 4757 | @end smallexample |
c906108c SS |
4758 | |
4759 | The left operand of @samp{@@} must reside in memory. Array values made | |
4760 | with @samp{@@} in this way behave just like other arrays in terms of | |
4761 | subscripting, and are coerced to pointers when used in expressions. | |
4762 | Artificial arrays most often appear in expressions via the value history | |
4763 | (@pxref{Value History, ,Value history}), after printing one out. | |
4764 | ||
4765 | Another way to create an artificial array is to use a cast. | |
4766 | This re-interprets a value as if it were an array. | |
4767 | The value need not be in memory: | |
474c8240 | 4768 | @smallexample |
c906108c SS |
4769 | (@value{GDBP}) p/x (short[2])0x12345678 |
4770 | $1 = @{0x1234, 0x5678@} | |
474c8240 | 4771 | @end smallexample |
c906108c SS |
4772 | |
4773 | As a convenience, if you leave the array length out (as in | |
c3f6f71d | 4774 | @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill |
c906108c | 4775 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: |
474c8240 | 4776 | @smallexample |
c906108c SS |
4777 | (@value{GDBP}) p/x (short[])0x12345678 |
4778 | $2 = @{0x1234, 0x5678@} | |
474c8240 | 4779 | @end smallexample |
c906108c SS |
4780 | |
4781 | Sometimes the artificial array mechanism is not quite enough; in | |
4782 | moderately complex data structures, the elements of interest may not | |
4783 | actually be adjacent---for example, if you are interested in the values | |
4784 | of pointers in an array. One useful work-around in this situation is | |
4785 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience | |
4786 | variables}) as a counter in an expression that prints the first | |
4787 | interesting value, and then repeat that expression via @key{RET}. For | |
4788 | instance, suppose you have an array @code{dtab} of pointers to | |
4789 | structures, and you are interested in the values of a field @code{fv} | |
4790 | in each structure. Here is an example of what you might type: | |
4791 | ||
474c8240 | 4792 | @smallexample |
c906108c SS |
4793 | set $i = 0 |
4794 | p dtab[$i++]->fv | |
4795 | @key{RET} | |
4796 | @key{RET} | |
4797 | @dots{} | |
474c8240 | 4798 | @end smallexample |
c906108c | 4799 | |
6d2ebf8b | 4800 | @node Output Formats |
c906108c SS |
4801 | @section Output formats |
4802 | ||
4803 | @cindex formatted output | |
4804 | @cindex output formats | |
4805 | By default, @value{GDBN} prints a value according to its data type. Sometimes | |
4806 | this is not what you want. For example, you might want to print a number | |
4807 | in hex, or a pointer in decimal. Or you might want to view data in memory | |
4808 | at a certain address as a character string or as an instruction. To do | |
4809 | these things, specify an @dfn{output format} when you print a value. | |
4810 | ||
4811 | The simplest use of output formats is to say how to print a value | |
4812 | already computed. This is done by starting the arguments of the | |
4813 | @code{print} command with a slash and a format letter. The format | |
4814 | letters supported are: | |
4815 | ||
4816 | @table @code | |
4817 | @item x | |
4818 | Regard the bits of the value as an integer, and print the integer in | |
4819 | hexadecimal. | |
4820 | ||
4821 | @item d | |
4822 | Print as integer in signed decimal. | |
4823 | ||
4824 | @item u | |
4825 | Print as integer in unsigned decimal. | |
4826 | ||
4827 | @item o | |
4828 | Print as integer in octal. | |
4829 | ||
4830 | @item t | |
4831 | Print as integer in binary. The letter @samp{t} stands for ``two''. | |
4832 | @footnote{@samp{b} cannot be used because these format letters are also | |
4833 | used with the @code{x} command, where @samp{b} stands for ``byte''; | |
d4f3574e | 4834 | see @ref{Memory,,Examining memory}.} |
c906108c SS |
4835 | |
4836 | @item a | |
4837 | @cindex unknown address, locating | |
3d67e040 | 4838 | @cindex locate address |
c906108c SS |
4839 | Print as an address, both absolute in hexadecimal and as an offset from |
4840 | the nearest preceding symbol. You can use this format used to discover | |
4841 | where (in what function) an unknown address is located: | |
4842 | ||
474c8240 | 4843 | @smallexample |
c906108c SS |
4844 | (@value{GDBP}) p/a 0x54320 |
4845 | $3 = 0x54320 <_initialize_vx+396> | |
474c8240 | 4846 | @end smallexample |
c906108c | 4847 | |
3d67e040 EZ |
4848 | @noindent |
4849 | The command @code{info symbol 0x54320} yields similar results. | |
4850 | @xref{Symbols, info symbol}. | |
4851 | ||
c906108c SS |
4852 | @item c |
4853 | Regard as an integer and print it as a character constant. | |
4854 | ||
4855 | @item f | |
4856 | Regard the bits of the value as a floating point number and print | |
4857 | using typical floating point syntax. | |
4858 | @end table | |
4859 | ||
4860 | For example, to print the program counter in hex (@pxref{Registers}), type | |
4861 | ||
474c8240 | 4862 | @smallexample |
c906108c | 4863 | p/x $pc |
474c8240 | 4864 | @end smallexample |
c906108c SS |
4865 | |
4866 | @noindent | |
4867 | Note that no space is required before the slash; this is because command | |
4868 | names in @value{GDBN} cannot contain a slash. | |
4869 | ||
4870 | To reprint the last value in the value history with a different format, | |
4871 | you can use the @code{print} command with just a format and no | |
4872 | expression. For example, @samp{p/x} reprints the last value in hex. | |
4873 | ||
6d2ebf8b | 4874 | @node Memory |
c906108c SS |
4875 | @section Examining memory |
4876 | ||
4877 | You can use the command @code{x} (for ``examine'') to examine memory in | |
4878 | any of several formats, independently of your program's data types. | |
4879 | ||
4880 | @cindex examining memory | |
4881 | @table @code | |
41afff9a | 4882 | @kindex x @r{(examine memory)} |
c906108c SS |
4883 | @item x/@var{nfu} @var{addr} |
4884 | @itemx x @var{addr} | |
4885 | @itemx x | |
4886 | Use the @code{x} command to examine memory. | |
4887 | @end table | |
4888 | ||
4889 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how | |
4890 | much memory to display and how to format it; @var{addr} is an | |
4891 | expression giving the address where you want to start displaying memory. | |
4892 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. | |
4893 | Several commands set convenient defaults for @var{addr}. | |
4894 | ||
4895 | @table @r | |
4896 | @item @var{n}, the repeat count | |
4897 | The repeat count is a decimal integer; the default is 1. It specifies | |
4898 | how much memory (counting by units @var{u}) to display. | |
4899 | @c This really is **decimal**; unaffected by 'set radix' as of GDB | |
4900 | @c 4.1.2. | |
4901 | ||
4902 | @item @var{f}, the display format | |
4903 | The display format is one of the formats used by @code{print}, | |
4904 | @samp{s} (null-terminated string), or @samp{i} (machine instruction). | |
4905 | The default is @samp{x} (hexadecimal) initially. | |
4906 | The default changes each time you use either @code{x} or @code{print}. | |
4907 | ||
4908 | @item @var{u}, the unit size | |
4909 | The unit size is any of | |
4910 | ||
4911 | @table @code | |
4912 | @item b | |
4913 | Bytes. | |
4914 | @item h | |
4915 | Halfwords (two bytes). | |
4916 | @item w | |
4917 | Words (four bytes). This is the initial default. | |
4918 | @item g | |
4919 | Giant words (eight bytes). | |
4920 | @end table | |
4921 | ||
4922 | Each time you specify a unit size with @code{x}, that size becomes the | |
4923 | default unit the next time you use @code{x}. (For the @samp{s} and | |
4924 | @samp{i} formats, the unit size is ignored and is normally not written.) | |
4925 | ||
4926 | @item @var{addr}, starting display address | |
4927 | @var{addr} is the address where you want @value{GDBN} to begin displaying | |
4928 | memory. The expression need not have a pointer value (though it may); | |
4929 | it is always interpreted as an integer address of a byte of memory. | |
4930 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for | |
4931 | @var{addr} is usually just after the last address examined---but several | |
4932 | other commands also set the default address: @code{info breakpoints} (to | |
4933 | the address of the last breakpoint listed), @code{info line} (to the | |
4934 | starting address of a line), and @code{print} (if you use it to display | |
4935 | a value from memory). | |
4936 | @end table | |
4937 | ||
4938 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords | |
4939 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), | |
4940 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four | |
4941 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; | |
d4f3574e | 4942 | @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). |
c906108c SS |
4943 | |
4944 | Since the letters indicating unit sizes are all distinct from the | |
4945 | letters specifying output formats, you do not have to remember whether | |
4946 | unit size or format comes first; either order works. The output | |
4947 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. | |
4948 | (However, the count @var{n} must come first; @samp{wx4} does not work.) | |
4949 | ||
4950 | Even though the unit size @var{u} is ignored for the formats @samp{s} | |
4951 | and @samp{i}, you might still want to use a count @var{n}; for example, | |
4952 | @samp{3i} specifies that you want to see three machine instructions, | |
4953 | including any operands. The command @code{disassemble} gives an | |
d4f3574e | 4954 | alternative way of inspecting machine instructions; see @ref{Machine |
c906108c SS |
4955 | Code,,Source and machine code}. |
4956 | ||
4957 | All the defaults for the arguments to @code{x} are designed to make it | |
4958 | easy to continue scanning memory with minimal specifications each time | |
4959 | you use @code{x}. For example, after you have inspected three machine | |
4960 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven | |
4961 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, | |
4962 | the repeat count @var{n} is used again; the other arguments default as | |
4963 | for successive uses of @code{x}. | |
4964 | ||
4965 | @cindex @code{$_}, @code{$__}, and value history | |
4966 | The addresses and contents printed by the @code{x} command are not saved | |
4967 | in the value history because there is often too much of them and they | |
4968 | would get in the way. Instead, @value{GDBN} makes these values available for | |
4969 | subsequent use in expressions as values of the convenience variables | |
4970 | @code{$_} and @code{$__}. After an @code{x} command, the last address | |
4971 | examined is available for use in expressions in the convenience variable | |
4972 | @code{$_}. The contents of that address, as examined, are available in | |
4973 | the convenience variable @code{$__}. | |
4974 | ||
4975 | If the @code{x} command has a repeat count, the address and contents saved | |
4976 | are from the last memory unit printed; this is not the same as the last | |
4977 | address printed if several units were printed on the last line of output. | |
4978 | ||
6d2ebf8b | 4979 | @node Auto Display |
c906108c SS |
4980 | @section Automatic display |
4981 | @cindex automatic display | |
4982 | @cindex display of expressions | |
4983 | ||
4984 | If you find that you want to print the value of an expression frequently | |
4985 | (to see how it changes), you might want to add it to the @dfn{automatic | |
4986 | display list} so that @value{GDBN} prints its value each time your program stops. | |
4987 | Each expression added to the list is given a number to identify it; | |
4988 | to remove an expression from the list, you specify that number. | |
4989 | The automatic display looks like this: | |
4990 | ||
474c8240 | 4991 | @smallexample |
c906108c SS |
4992 | 2: foo = 38 |
4993 | 3: bar[5] = (struct hack *) 0x3804 | |
474c8240 | 4994 | @end smallexample |
c906108c SS |
4995 | |
4996 | @noindent | |
4997 | This display shows item numbers, expressions and their current values. As with | |
4998 | displays you request manually using @code{x} or @code{print}, you can | |
4999 | specify the output format you prefer; in fact, @code{display} decides | |
5000 | whether to use @code{print} or @code{x} depending on how elaborate your | |
5001 | format specification is---it uses @code{x} if you specify a unit size, | |
5002 | or one of the two formats (@samp{i} and @samp{s}) that are only | |
5003 | supported by @code{x}; otherwise it uses @code{print}. | |
5004 | ||
5005 | @table @code | |
5006 | @kindex display | |
d4f3574e SS |
5007 | @item display @var{expr} |
5008 | Add the expression @var{expr} to the list of expressions to display | |
c906108c SS |
5009 | each time your program stops. @xref{Expressions, ,Expressions}. |
5010 | ||
5011 | @code{display} does not repeat if you press @key{RET} again after using it. | |
5012 | ||
d4f3574e | 5013 | @item display/@var{fmt} @var{expr} |
c906108c | 5014 | For @var{fmt} specifying only a display format and not a size or |
d4f3574e | 5015 | count, add the expression @var{expr} to the auto-display list but |
c906108c SS |
5016 | arrange to display it each time in the specified format @var{fmt}. |
5017 | @xref{Output Formats,,Output formats}. | |
5018 | ||
5019 | @item display/@var{fmt} @var{addr} | |
5020 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a | |
5021 | number of units, add the expression @var{addr} as a memory address to | |
5022 | be examined each time your program stops. Examining means in effect | |
5023 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. | |
5024 | @end table | |
5025 | ||
5026 | For example, @samp{display/i $pc} can be helpful, to see the machine | |
5027 | instruction about to be executed each time execution stops (@samp{$pc} | |
d4f3574e | 5028 | is a common name for the program counter; @pxref{Registers, ,Registers}). |
c906108c SS |
5029 | |
5030 | @table @code | |
5031 | @kindex delete display | |
5032 | @kindex undisplay | |
5033 | @item undisplay @var{dnums}@dots{} | |
5034 | @itemx delete display @var{dnums}@dots{} | |
5035 | Remove item numbers @var{dnums} from the list of expressions to display. | |
5036 | ||
5037 | @code{undisplay} does not repeat if you press @key{RET} after using it. | |
5038 | (Otherwise you would just get the error @samp{No display number @dots{}}.) | |
5039 | ||
5040 | @kindex disable display | |
5041 | @item disable display @var{dnums}@dots{} | |
5042 | Disable the display of item numbers @var{dnums}. A disabled display | |
5043 | item is not printed automatically, but is not forgotten. It may be | |
5044 | enabled again later. | |
5045 | ||
5046 | @kindex enable display | |
5047 | @item enable display @var{dnums}@dots{} | |
5048 | Enable display of item numbers @var{dnums}. It becomes effective once | |
5049 | again in auto display of its expression, until you specify otherwise. | |
5050 | ||
5051 | @item display | |
5052 | Display the current values of the expressions on the list, just as is | |
5053 | done when your program stops. | |
5054 | ||
5055 | @kindex info display | |
5056 | @item info display | |
5057 | Print the list of expressions previously set up to display | |
5058 | automatically, each one with its item number, but without showing the | |
5059 | values. This includes disabled expressions, which are marked as such. | |
5060 | It also includes expressions which would not be displayed right now | |
5061 | because they refer to automatic variables not currently available. | |
5062 | @end table | |
5063 | ||
5064 | If a display expression refers to local variables, then it does not make | |
5065 | sense outside the lexical context for which it was set up. Such an | |
5066 | expression is disabled when execution enters a context where one of its | |
5067 | variables is not defined. For example, if you give the command | |
5068 | @code{display last_char} while inside a function with an argument | |
5069 | @code{last_char}, @value{GDBN} displays this argument while your program | |
5070 | continues to stop inside that function. When it stops elsewhere---where | |
5071 | there is no variable @code{last_char}---the display is disabled | |
5072 | automatically. The next time your program stops where @code{last_char} | |
5073 | is meaningful, you can enable the display expression once again. | |
5074 | ||
6d2ebf8b | 5075 | @node Print Settings |
c906108c SS |
5076 | @section Print settings |
5077 | ||
5078 | @cindex format options | |
5079 | @cindex print settings | |
5080 | @value{GDBN} provides the following ways to control how arrays, structures, | |
5081 | and symbols are printed. | |
5082 | ||
5083 | @noindent | |
5084 | These settings are useful for debugging programs in any language: | |
5085 | ||
5086 | @table @code | |
5087 | @kindex set print address | |
5088 | @item set print address | |
5089 | @itemx set print address on | |
5090 | @value{GDBN} prints memory addresses showing the location of stack | |
5091 | traces, structure values, pointer values, breakpoints, and so forth, | |
5092 | even when it also displays the contents of those addresses. The default | |
5093 | is @code{on}. For example, this is what a stack frame display looks like with | |
5094 | @code{set print address on}: | |
5095 | ||
5096 | @smallexample | |
5097 | @group | |
5098 | (@value{GDBP}) f | |
5099 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") | |
5100 | at input.c:530 | |
5101 | 530 if (lquote != def_lquote) | |
5102 | @end group | |
5103 | @end smallexample | |
5104 | ||
5105 | @item set print address off | |
5106 | Do not print addresses when displaying their contents. For example, | |
5107 | this is the same stack frame displayed with @code{set print address off}: | |
5108 | ||
5109 | @smallexample | |
5110 | @group | |
5111 | (@value{GDBP}) set print addr off | |
5112 | (@value{GDBP}) f | |
5113 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 | |
5114 | 530 if (lquote != def_lquote) | |
5115 | @end group | |
5116 | @end smallexample | |
5117 | ||
5118 | You can use @samp{set print address off} to eliminate all machine | |
5119 | dependent displays from the @value{GDBN} interface. For example, with | |
5120 | @code{print address off}, you should get the same text for backtraces on | |
5121 | all machines---whether or not they involve pointer arguments. | |
5122 | ||
5123 | @kindex show print address | |
5124 | @item show print address | |
5125 | Show whether or not addresses are to be printed. | |
5126 | @end table | |
5127 | ||
5128 | When @value{GDBN} prints a symbolic address, it normally prints the | |
5129 | closest earlier symbol plus an offset. If that symbol does not uniquely | |
5130 | identify the address (for example, it is a name whose scope is a single | |
5131 | source file), you may need to clarify. One way to do this is with | |
5132 | @code{info line}, for example @samp{info line *0x4537}. Alternately, | |
5133 | you can set @value{GDBN} to print the source file and line number when | |
5134 | it prints a symbolic address: | |
5135 | ||
5136 | @table @code | |
5137 | @kindex set print symbol-filename | |
5138 | @item set print symbol-filename on | |
5139 | Tell @value{GDBN} to print the source file name and line number of a | |
5140 | symbol in the symbolic form of an address. | |
5141 | ||
5142 | @item set print symbol-filename off | |
5143 | Do not print source file name and line number of a symbol. This is the | |
5144 | default. | |
5145 | ||
5146 | @kindex show print symbol-filename | |
5147 | @item show print symbol-filename | |
5148 | Show whether or not @value{GDBN} will print the source file name and | |
5149 | line number of a symbol in the symbolic form of an address. | |
5150 | @end table | |
5151 | ||
5152 | Another situation where it is helpful to show symbol filenames and line | |
5153 | numbers is when disassembling code; @value{GDBN} shows you the line | |
5154 | number and source file that corresponds to each instruction. | |
5155 | ||
5156 | Also, you may wish to see the symbolic form only if the address being | |
5157 | printed is reasonably close to the closest earlier symbol: | |
5158 | ||
5159 | @table @code | |
5160 | @kindex set print max-symbolic-offset | |
5161 | @item set print max-symbolic-offset @var{max-offset} | |
5162 | Tell @value{GDBN} to only display the symbolic form of an address if the | |
5163 | offset between the closest earlier symbol and the address is less than | |
5d161b24 | 5164 | @var{max-offset}. The default is 0, which tells @value{GDBN} |
c906108c SS |
5165 | to always print the symbolic form of an address if any symbol precedes it. |
5166 | ||
5167 | @kindex show print max-symbolic-offset | |
5168 | @item show print max-symbolic-offset | |
5169 | Ask how large the maximum offset is that @value{GDBN} prints in a | |
5170 | symbolic address. | |
5171 | @end table | |
5172 | ||
5173 | @cindex wild pointer, interpreting | |
5174 | @cindex pointer, finding referent | |
5175 | If you have a pointer and you are not sure where it points, try | |
5176 | @samp{set print symbol-filename on}. Then you can determine the name | |
5177 | and source file location of the variable where it points, using | |
5178 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. | |
5179 | For example, here @value{GDBN} shows that a variable @code{ptt} points | |
5180 | at another variable @code{t}, defined in @file{hi2.c}: | |
5181 | ||
474c8240 | 5182 | @smallexample |
c906108c SS |
5183 | (@value{GDBP}) set print symbol-filename on |
5184 | (@value{GDBP}) p/a ptt | |
5185 | $4 = 0xe008 <t in hi2.c> | |
474c8240 | 5186 | @end smallexample |
c906108c SS |
5187 | |
5188 | @quotation | |
5189 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} | |
5190 | does not show the symbol name and filename of the referent, even with | |
5191 | the appropriate @code{set print} options turned on. | |
5192 | @end quotation | |
5193 | ||
5194 | Other settings control how different kinds of objects are printed: | |
5195 | ||
5196 | @table @code | |
5197 | @kindex set print array | |
5198 | @item set print array | |
5199 | @itemx set print array on | |
5200 | Pretty print arrays. This format is more convenient to read, | |
5201 | but uses more space. The default is off. | |
5202 | ||
5203 | @item set print array off | |
5204 | Return to compressed format for arrays. | |
5205 | ||
5206 | @kindex show print array | |
5207 | @item show print array | |
5208 | Show whether compressed or pretty format is selected for displaying | |
5209 | arrays. | |
5210 | ||
5211 | @kindex set print elements | |
5212 | @item set print elements @var{number-of-elements} | |
5213 | Set a limit on how many elements of an array @value{GDBN} will print. | |
5214 | If @value{GDBN} is printing a large array, it stops printing after it has | |
5215 | printed the number of elements set by the @code{set print elements} command. | |
5216 | This limit also applies to the display of strings. | |
d4f3574e | 5217 | When @value{GDBN} starts, this limit is set to 200. |
c906108c SS |
5218 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
5219 | ||
5220 | @kindex show print elements | |
5221 | @item show print elements | |
5222 | Display the number of elements of a large array that @value{GDBN} will print. | |
5223 | If the number is 0, then the printing is unlimited. | |
5224 | ||
5225 | @kindex set print null-stop | |
5226 | @item set print null-stop | |
5227 | Cause @value{GDBN} to stop printing the characters of an array when the first | |
d4f3574e | 5228 | @sc{null} is encountered. This is useful when large arrays actually |
c906108c | 5229 | contain only short strings. |
d4f3574e | 5230 | The default is off. |
c906108c SS |
5231 | |
5232 | @kindex set print pretty | |
5233 | @item set print pretty on | |
5d161b24 | 5234 | Cause @value{GDBN} to print structures in an indented format with one member |
c906108c SS |
5235 | per line, like this: |
5236 | ||
5237 | @smallexample | |
5238 | @group | |
5239 | $1 = @{ | |
5240 | next = 0x0, | |
5241 | flags = @{ | |
5242 | sweet = 1, | |
5243 | sour = 1 | |
5244 | @}, | |
5245 | meat = 0x54 "Pork" | |
5246 | @} | |
5247 | @end group | |
5248 | @end smallexample | |
5249 | ||
5250 | @item set print pretty off | |
5251 | Cause @value{GDBN} to print structures in a compact format, like this: | |
5252 | ||
5253 | @smallexample | |
5254 | @group | |
5255 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ | |
5256 | meat = 0x54 "Pork"@} | |
5257 | @end group | |
5258 | @end smallexample | |
5259 | ||
5260 | @noindent | |
5261 | This is the default format. | |
5262 | ||
5263 | @kindex show print pretty | |
5264 | @item show print pretty | |
5265 | Show which format @value{GDBN} is using to print structures. | |
5266 | ||
5267 | @kindex set print sevenbit-strings | |
5268 | @item set print sevenbit-strings on | |
5269 | Print using only seven-bit characters; if this option is set, | |
5270 | @value{GDBN} displays any eight-bit characters (in strings or | |
5271 | character values) using the notation @code{\}@var{nnn}. This setting is | |
5272 | best if you are working in English (@sc{ascii}) and you use the | |
5273 | high-order bit of characters as a marker or ``meta'' bit. | |
5274 | ||
5275 | @item set print sevenbit-strings off | |
5276 | Print full eight-bit characters. This allows the use of more | |
5277 | international character sets, and is the default. | |
5278 | ||
5279 | @kindex show print sevenbit-strings | |
5280 | @item show print sevenbit-strings | |
5281 | Show whether or not @value{GDBN} is printing only seven-bit characters. | |
5282 | ||
5283 | @kindex set print union | |
5284 | @item set print union on | |
5d161b24 | 5285 | Tell @value{GDBN} to print unions which are contained in structures. This |
c906108c SS |
5286 | is the default setting. |
5287 | ||
5288 | @item set print union off | |
5289 | Tell @value{GDBN} not to print unions which are contained in structures. | |
5290 | ||
5291 | @kindex show print union | |
5292 | @item show print union | |
5293 | Ask @value{GDBN} whether or not it will print unions which are contained in | |
5294 | structures. | |
5295 | ||
5296 | For example, given the declarations | |
5297 | ||
5298 | @smallexample | |
5299 | typedef enum @{Tree, Bug@} Species; | |
5300 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; | |
5d161b24 | 5301 | typedef enum @{Caterpillar, Cocoon, Butterfly@} |
c906108c SS |
5302 | Bug_forms; |
5303 | ||
5304 | struct thing @{ | |
5305 | Species it; | |
5306 | union @{ | |
5307 | Tree_forms tree; | |
5308 | Bug_forms bug; | |
5309 | @} form; | |
5310 | @}; | |
5311 | ||
5312 | struct thing foo = @{Tree, @{Acorn@}@}; | |
5313 | @end smallexample | |
5314 | ||
5315 | @noindent | |
5316 | with @code{set print union on} in effect @samp{p foo} would print | |
5317 | ||
5318 | @smallexample | |
5319 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} | |
5320 | @end smallexample | |
5321 | ||
5322 | @noindent | |
5323 | and with @code{set print union off} in effect it would print | |
5324 | ||
5325 | @smallexample | |
5326 | $1 = @{it = Tree, form = @{...@}@} | |
5327 | @end smallexample | |
5328 | @end table | |
5329 | ||
c906108c SS |
5330 | @need 1000 |
5331 | @noindent | |
b37052ae | 5332 | These settings are of interest when debugging C@t{++} programs: |
c906108c SS |
5333 | |
5334 | @table @code | |
5335 | @cindex demangling | |
5336 | @kindex set print demangle | |
5337 | @item set print demangle | |
5338 | @itemx set print demangle on | |
b37052ae | 5339 | Print C@t{++} names in their source form rather than in the encoded |
c906108c | 5340 | (``mangled'') form passed to the assembler and linker for type-safe |
d4f3574e | 5341 | linkage. The default is on. |
c906108c SS |
5342 | |
5343 | @kindex show print demangle | |
5344 | @item show print demangle | |
b37052ae | 5345 | Show whether C@t{++} names are printed in mangled or demangled form. |
c906108c SS |
5346 | |
5347 | @kindex set print asm-demangle | |
5348 | @item set print asm-demangle | |
5349 | @itemx set print asm-demangle on | |
b37052ae | 5350 | Print C@t{++} names in their source form rather than their mangled form, even |
c906108c SS |
5351 | in assembler code printouts such as instruction disassemblies. |
5352 | The default is off. | |
5353 | ||
5354 | @kindex show print asm-demangle | |
5355 | @item show print asm-demangle | |
b37052ae | 5356 | Show whether C@t{++} names in assembly listings are printed in mangled |
c906108c SS |
5357 | or demangled form. |
5358 | ||
5359 | @kindex set demangle-style | |
b37052ae EZ |
5360 | @cindex C@t{++} symbol decoding style |
5361 | @cindex symbol decoding style, C@t{++} | |
c906108c SS |
5362 | @item set demangle-style @var{style} |
5363 | Choose among several encoding schemes used by different compilers to | |
b37052ae | 5364 | represent C@t{++} names. The choices for @var{style} are currently: |
c906108c SS |
5365 | |
5366 | @table @code | |
5367 | @item auto | |
5368 | Allow @value{GDBN} to choose a decoding style by inspecting your program. | |
5369 | ||
5370 | @item gnu | |
b37052ae | 5371 | Decode based on the @sc{gnu} C@t{++} compiler (@code{g++}) encoding algorithm. |
c906108c | 5372 | This is the default. |
c906108c SS |
5373 | |
5374 | @item hp | |
b37052ae | 5375 | Decode based on the HP ANSI C@t{++} (@code{aCC}) encoding algorithm. |
c906108c SS |
5376 | |
5377 | @item lucid | |
b37052ae | 5378 | Decode based on the Lucid C@t{++} compiler (@code{lcc}) encoding algorithm. |
c906108c SS |
5379 | |
5380 | @item arm | |
b37052ae | 5381 | Decode using the algorithm in the @cite{C@t{++} Annotated Reference Manual}. |
c906108c SS |
5382 | @strong{Warning:} this setting alone is not sufficient to allow |
5383 | debugging @code{cfront}-generated executables. @value{GDBN} would | |
5384 | require further enhancement to permit that. | |
5385 | ||
5386 | @end table | |
5387 | If you omit @var{style}, you will see a list of possible formats. | |
5388 | ||
5389 | @kindex show demangle-style | |
5390 | @item show demangle-style | |
b37052ae | 5391 | Display the encoding style currently in use for decoding C@t{++} symbols. |
c906108c SS |
5392 | |
5393 | @kindex set print object | |
5394 | @item set print object | |
5395 | @itemx set print object on | |
5396 | When displaying a pointer to an object, identify the @emph{actual} | |
5397 | (derived) type of the object rather than the @emph{declared} type, using | |
5398 | the virtual function table. | |
5399 | ||
5400 | @item set print object off | |
5401 | Display only the declared type of objects, without reference to the | |
5402 | virtual function table. This is the default setting. | |
5403 | ||
5404 | @kindex show print object | |
5405 | @item show print object | |
5406 | Show whether actual, or declared, object types are displayed. | |
5407 | ||
5408 | @kindex set print static-members | |
5409 | @item set print static-members | |
5410 | @itemx set print static-members on | |
b37052ae | 5411 | Print static members when displaying a C@t{++} object. The default is on. |
c906108c SS |
5412 | |
5413 | @item set print static-members off | |
b37052ae | 5414 | Do not print static members when displaying a C@t{++} object. |
c906108c SS |
5415 | |
5416 | @kindex show print static-members | |
5417 | @item show print static-members | |
b37052ae | 5418 | Show whether C@t{++} static members are printed, or not. |
c906108c SS |
5419 | |
5420 | @c These don't work with HP ANSI C++ yet. | |
5421 | @kindex set print vtbl | |
5422 | @item set print vtbl | |
5423 | @itemx set print vtbl on | |
b37052ae | 5424 | Pretty print C@t{++} virtual function tables. The default is off. |
c906108c | 5425 | (The @code{vtbl} commands do not work on programs compiled with the HP |
b37052ae | 5426 | ANSI C@t{++} compiler (@code{aCC}).) |
c906108c SS |
5427 | |
5428 | @item set print vtbl off | |
b37052ae | 5429 | Do not pretty print C@t{++} virtual function tables. |
c906108c SS |
5430 | |
5431 | @kindex show print vtbl | |
5432 | @item show print vtbl | |
b37052ae | 5433 | Show whether C@t{++} virtual function tables are pretty printed, or not. |
c906108c | 5434 | @end table |
c906108c | 5435 | |
6d2ebf8b | 5436 | @node Value History |
c906108c SS |
5437 | @section Value history |
5438 | ||
5439 | @cindex value history | |
5d161b24 DB |
5440 | Values printed by the @code{print} command are saved in the @value{GDBN} |
5441 | @dfn{value history}. This allows you to refer to them in other expressions. | |
5442 | Values are kept until the symbol table is re-read or discarded | |
5443 | (for example with the @code{file} or @code{symbol-file} commands). | |
5444 | When the symbol table changes, the value history is discarded, | |
5445 | since the values may contain pointers back to the types defined in the | |
c906108c SS |
5446 | symbol table. |
5447 | ||
5448 | @cindex @code{$} | |
5449 | @cindex @code{$$} | |
5450 | @cindex history number | |
5451 | The values printed are given @dfn{history numbers} by which you can | |
5452 | refer to them. These are successive integers starting with one. | |
5453 | @code{print} shows you the history number assigned to a value by | |
5454 | printing @samp{$@var{num} = } before the value; here @var{num} is the | |
5455 | history number. | |
5456 | ||
5457 | To refer to any previous value, use @samp{$} followed by the value's | |
5458 | history number. The way @code{print} labels its output is designed to | |
5459 | remind you of this. Just @code{$} refers to the most recent value in | |
5460 | the history, and @code{$$} refers to the value before that. | |
5461 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} | |
5462 | is the value just prior to @code{$$}, @code{$$1} is equivalent to | |
5463 | @code{$$}, and @code{$$0} is equivalent to @code{$}. | |
5464 | ||
5465 | For example, suppose you have just printed a pointer to a structure and | |
5466 | want to see the contents of the structure. It suffices to type | |
5467 | ||
474c8240 | 5468 | @smallexample |
c906108c | 5469 | p *$ |
474c8240 | 5470 | @end smallexample |
c906108c SS |
5471 | |
5472 | If you have a chain of structures where the component @code{next} points | |
5473 | to the next one, you can print the contents of the next one with this: | |
5474 | ||
474c8240 | 5475 | @smallexample |
c906108c | 5476 | p *$.next |
474c8240 | 5477 | @end smallexample |
c906108c SS |
5478 | |
5479 | @noindent | |
5480 | You can print successive links in the chain by repeating this | |
5481 | command---which you can do by just typing @key{RET}. | |
5482 | ||
5483 | Note that the history records values, not expressions. If the value of | |
5484 | @code{x} is 4 and you type these commands: | |
5485 | ||
474c8240 | 5486 | @smallexample |
c906108c SS |
5487 | print x |
5488 | set x=5 | |
474c8240 | 5489 | @end smallexample |
c906108c SS |
5490 | |
5491 | @noindent | |
5492 | then the value recorded in the value history by the @code{print} command | |
5493 | remains 4 even though the value of @code{x} has changed. | |
5494 | ||
5495 | @table @code | |
5496 | @kindex show values | |
5497 | @item show values | |
5498 | Print the last ten values in the value history, with their item numbers. | |
5499 | This is like @samp{p@ $$9} repeated ten times, except that @code{show | |
5500 | values} does not change the history. | |
5501 | ||
5502 | @item show values @var{n} | |
5503 | Print ten history values centered on history item number @var{n}. | |
5504 | ||
5505 | @item show values + | |
5506 | Print ten history values just after the values last printed. If no more | |
5507 | values are available, @code{show values +} produces no display. | |
5508 | @end table | |
5509 | ||
5510 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the | |
5511 | same effect as @samp{show values +}. | |
5512 | ||
6d2ebf8b | 5513 | @node Convenience Vars |
c906108c SS |
5514 | @section Convenience variables |
5515 | ||
5516 | @cindex convenience variables | |
5517 | @value{GDBN} provides @dfn{convenience variables} that you can use within | |
5518 | @value{GDBN} to hold on to a value and refer to it later. These variables | |
5519 | exist entirely within @value{GDBN}; they are not part of your program, and | |
5520 | setting a convenience variable has no direct effect on further execution | |
5521 | of your program. That is why you can use them freely. | |
5522 | ||
5523 | Convenience variables are prefixed with @samp{$}. Any name preceded by | |
5524 | @samp{$} can be used for a convenience variable, unless it is one of | |
d4f3574e | 5525 | the predefined machine-specific register names (@pxref{Registers, ,Registers}). |
c906108c SS |
5526 | (Value history references, in contrast, are @emph{numbers} preceded |
5527 | by @samp{$}. @xref{Value History, ,Value history}.) | |
5528 | ||
5529 | You can save a value in a convenience variable with an assignment | |
5530 | expression, just as you would set a variable in your program. | |
5531 | For example: | |
5532 | ||
474c8240 | 5533 | @smallexample |
c906108c | 5534 | set $foo = *object_ptr |
474c8240 | 5535 | @end smallexample |
c906108c SS |
5536 | |
5537 | @noindent | |
5538 | would save in @code{$foo} the value contained in the object pointed to by | |
5539 | @code{object_ptr}. | |
5540 | ||
5541 | Using a convenience variable for the first time creates it, but its | |
5542 | value is @code{void} until you assign a new value. You can alter the | |
5543 | value with another assignment at any time. | |
5544 | ||
5545 | Convenience variables have no fixed types. You can assign a convenience | |
5546 | variable any type of value, including structures and arrays, even if | |
5547 | that variable already has a value of a different type. The convenience | |
5548 | variable, when used as an expression, has the type of its current value. | |
5549 | ||
5550 | @table @code | |
5551 | @kindex show convenience | |
5552 | @item show convenience | |
5553 | Print a list of convenience variables used so far, and their values. | |
d4f3574e | 5554 | Abbreviated @code{show conv}. |
c906108c SS |
5555 | @end table |
5556 | ||
5557 | One of the ways to use a convenience variable is as a counter to be | |
5558 | incremented or a pointer to be advanced. For example, to print | |
5559 | a field from successive elements of an array of structures: | |
5560 | ||
474c8240 | 5561 | @smallexample |
c906108c SS |
5562 | set $i = 0 |
5563 | print bar[$i++]->contents | |
474c8240 | 5564 | @end smallexample |
c906108c | 5565 | |
d4f3574e SS |
5566 | @noindent |
5567 | Repeat that command by typing @key{RET}. | |
c906108c SS |
5568 | |
5569 | Some convenience variables are created automatically by @value{GDBN} and given | |
5570 | values likely to be useful. | |
5571 | ||
5572 | @table @code | |
41afff9a | 5573 | @vindex $_@r{, convenience variable} |
c906108c SS |
5574 | @item $_ |
5575 | The variable @code{$_} is automatically set by the @code{x} command to | |
5576 | the last address examined (@pxref{Memory, ,Examining memory}). Other | |
5577 | commands which provide a default address for @code{x} to examine also | |
5578 | set @code{$_} to that address; these commands include @code{info line} | |
5579 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} | |
5580 | except when set by the @code{x} command, in which case it is a pointer | |
5581 | to the type of @code{$__}. | |
5582 | ||
41afff9a | 5583 | @vindex $__@r{, convenience variable} |
c906108c SS |
5584 | @item $__ |
5585 | The variable @code{$__} is automatically set by the @code{x} command | |
5586 | to the value found in the last address examined. Its type is chosen | |
5587 | to match the format in which the data was printed. | |
5588 | ||
5589 | @item $_exitcode | |
41afff9a | 5590 | @vindex $_exitcode@r{, convenience variable} |
c906108c SS |
5591 | The variable @code{$_exitcode} is automatically set to the exit code when |
5592 | the program being debugged terminates. | |
5593 | @end table | |
5594 | ||
53a5351d JM |
5595 | On HP-UX systems, if you refer to a function or variable name that |
5596 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
5597 | name first, before it searches for a convenience variable. | |
c906108c | 5598 | |
6d2ebf8b | 5599 | @node Registers |
c906108c SS |
5600 | @section Registers |
5601 | ||
5602 | @cindex registers | |
5603 | You can refer to machine register contents, in expressions, as variables | |
5604 | with names starting with @samp{$}. The names of registers are different | |
5605 | for each machine; use @code{info registers} to see the names used on | |
5606 | your machine. | |
5607 | ||
5608 | @table @code | |
5609 | @kindex info registers | |
5610 | @item info registers | |
5611 | Print the names and values of all registers except floating-point | |
c85508ee | 5612 | and vector registers (in the selected stack frame). |
c906108c SS |
5613 | |
5614 | @kindex info all-registers | |
5615 | @cindex floating point registers | |
5616 | @item info all-registers | |
5617 | Print the names and values of all registers, including floating-point | |
c85508ee | 5618 | and vector registers (in the selected stack frame). |
c906108c SS |
5619 | |
5620 | @item info registers @var{regname} @dots{} | |
5621 | Print the @dfn{relativized} value of each specified register @var{regname}. | |
5d161b24 DB |
5622 | As discussed in detail below, register values are normally relative to |
5623 | the selected stack frame. @var{regname} may be any register name valid on | |
c906108c SS |
5624 | the machine you are using, with or without the initial @samp{$}. |
5625 | @end table | |
5626 | ||
5627 | @value{GDBN} has four ``standard'' register names that are available (in | |
5628 | expressions) on most machines---whenever they do not conflict with an | |
5629 | architecture's canonical mnemonics for registers. The register names | |
5630 | @code{$pc} and @code{$sp} are used for the program counter register and | |
5631 | the stack pointer. @code{$fp} is used for a register that contains a | |
5632 | pointer to the current stack frame, and @code{$ps} is used for a | |
5633 | register that contains the processor status. For example, | |
5634 | you could print the program counter in hex with | |
5635 | ||
474c8240 | 5636 | @smallexample |
c906108c | 5637 | p/x $pc |
474c8240 | 5638 | @end smallexample |
c906108c SS |
5639 | |
5640 | @noindent | |
5641 | or print the instruction to be executed next with | |
5642 | ||
474c8240 | 5643 | @smallexample |
c906108c | 5644 | x/i $pc |
474c8240 | 5645 | @end smallexample |
c906108c SS |
5646 | |
5647 | @noindent | |
5648 | or add four to the stack pointer@footnote{This is a way of removing | |
5649 | one word from the stack, on machines where stacks grow downward in | |
5650 | memory (most machines, nowadays). This assumes that the innermost | |
5651 | stack frame is selected; setting @code{$sp} is not allowed when other | |
5652 | stack frames are selected. To pop entire frames off the stack, | |
5653 | regardless of machine architecture, use @code{return}; | |
d4f3574e | 5654 | see @ref{Returning, ,Returning from a function}.} with |
c906108c | 5655 | |
474c8240 | 5656 | @smallexample |
c906108c | 5657 | set $sp += 4 |
474c8240 | 5658 | @end smallexample |
c906108c SS |
5659 | |
5660 | Whenever possible, these four standard register names are available on | |
5661 | your machine even though the machine has different canonical mnemonics, | |
5662 | so long as there is no conflict. The @code{info registers} command | |
5663 | shows the canonical names. For example, on the SPARC, @code{info | |
5664 | registers} displays the processor status register as @code{$psr} but you | |
d4f3574e SS |
5665 | can also refer to it as @code{$ps}; and on x86-based machines @code{$ps} |
5666 | is an alias for the @sc{eflags} register. | |
c906108c SS |
5667 | |
5668 | @value{GDBN} always considers the contents of an ordinary register as an | |
5669 | integer when the register is examined in this way. Some machines have | |
5670 | special registers which can hold nothing but floating point; these | |
5671 | registers are considered to have floating point values. There is no way | |
5672 | to refer to the contents of an ordinary register as floating point value | |
5673 | (although you can @emph{print} it as a floating point value with | |
5674 | @samp{print/f $@var{regname}}). | |
5675 | ||
5676 | Some registers have distinct ``raw'' and ``virtual'' data formats. This | |
5677 | means that the data format in which the register contents are saved by | |
5678 | the operating system is not the same one that your program normally | |
5679 | sees. For example, the registers of the 68881 floating point | |
5680 | coprocessor are always saved in ``extended'' (raw) format, but all C | |
5681 | programs expect to work with ``double'' (virtual) format. In such | |
5d161b24 | 5682 | cases, @value{GDBN} normally works with the virtual format only (the format |
c906108c SS |
5683 | that makes sense for your program), but the @code{info registers} command |
5684 | prints the data in both formats. | |
5685 | ||
5686 | Normally, register values are relative to the selected stack frame | |
5687 | (@pxref{Selection, ,Selecting a frame}). This means that you get the | |
5688 | value that the register would contain if all stack frames farther in | |
5689 | were exited and their saved registers restored. In order to see the | |
5690 | true contents of hardware registers, you must select the innermost | |
5691 | frame (with @samp{frame 0}). | |
5692 | ||
5693 | However, @value{GDBN} must deduce where registers are saved, from the machine | |
5694 | code generated by your compiler. If some registers are not saved, or if | |
5695 | @value{GDBN} is unable to locate the saved registers, the selected stack | |
5696 | frame makes no difference. | |
5697 | ||
6d2ebf8b | 5698 | @node Floating Point Hardware |
c906108c SS |
5699 | @section Floating point hardware |
5700 | @cindex floating point | |
5701 | ||
5702 | Depending on the configuration, @value{GDBN} may be able to give | |
5703 | you more information about the status of the floating point hardware. | |
5704 | ||
5705 | @table @code | |
5706 | @kindex info float | |
5707 | @item info float | |
5708 | Display hardware-dependent information about the floating | |
5709 | point unit. The exact contents and layout vary depending on the | |
5710 | floating point chip. Currently, @samp{info float} is supported on | |
5711 | the ARM and x86 machines. | |
5712 | @end table | |
c906108c | 5713 | |
e76f1f2e AC |
5714 | @node Vector Unit |
5715 | @section Vector Unit | |
5716 | @cindex vector unit | |
5717 | ||
5718 | Depending on the configuration, @value{GDBN} may be able to give you | |
5719 | more information about the status of the vector unit. | |
5720 | ||
5721 | @table @code | |
5722 | @kindex info vector | |
5723 | @item info vector | |
5724 | Display information about the vector unit. The exact contents and | |
5725 | layout vary depending on the hardware. | |
5726 | @end table | |
5727 | ||
29e57380 | 5728 | @node Memory Region Attributes |
16d9dec6 | 5729 | @section Memory region attributes |
29e57380 C |
5730 | @cindex memory region attributes |
5731 | ||
5732 | @dfn{Memory region attributes} allow you to describe special handling | |
5733 | required by regions of your target's memory. @value{GDBN} uses attributes | |
5734 | to determine whether to allow certain types of memory accesses; whether to | |
5735 | use specific width accesses; and whether to cache target memory. | |
5736 | ||
5737 | Defined memory regions can be individually enabled and disabled. When a | |
5738 | memory region is disabled, @value{GDBN} uses the default attributes when | |
5739 | accessing memory in that region. Similarly, if no memory regions have | |
5740 | been defined, @value{GDBN} uses the default attributes when accessing | |
5741 | all memory. | |
5742 | ||
5743 | When a memory region is defined, it is given a number to identify it; | |
5744 | to enable, disable, or remove a memory region, you specify that number. | |
5745 | ||
5746 | @table @code | |
5747 | @kindex mem | |
bfac230e DH |
5748 | @item mem @var{lower} @var{upper} @var{attributes}@dots{} |
5749 | Define memory region bounded by @var{lower} and @var{upper} with | |
5750 | attributes @var{attributes}@dots{}. Note that @var{upper} == 0 is a | |
5751 | special case: it is treated as the the target's maximum memory address. | |
5752 | (0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.) | |
29e57380 C |
5753 | |
5754 | @kindex delete mem | |
5755 | @item delete mem @var{nums}@dots{} | |
59649f2e | 5756 | Remove memory regions @var{nums}@dots{}. |
29e57380 C |
5757 | |
5758 | @kindex disable mem | |
5759 | @item disable mem @var{nums}@dots{} | |
59649f2e | 5760 | Disable memory regions @var{nums}@dots{}. |
29e57380 C |
5761 | A disabled memory region is not forgotten. |
5762 | It may be enabled again later. | |
5763 | ||
5764 | @kindex enable mem | |
5765 | @item enable mem @var{nums}@dots{} | |
59649f2e | 5766 | Enable memory regions @var{nums}@dots{}. |
29e57380 C |
5767 | |
5768 | @kindex info mem | |
5769 | @item info mem | |
5770 | Print a table of all defined memory regions, with the following columns | |
5771 | for each region. | |
5772 | ||
5773 | @table @emph | |
5774 | @item Memory Region Number | |
5775 | @item Enabled or Disabled. | |
5776 | Enabled memory regions are marked with @samp{y}. | |
5777 | Disabled memory regions are marked with @samp{n}. | |
5778 | ||
5779 | @item Lo Address | |
5780 | The address defining the inclusive lower bound of the memory region. | |
5781 | ||
5782 | @item Hi Address | |
5783 | The address defining the exclusive upper bound of the memory region. | |
5784 | ||
5785 | @item Attributes | |
5786 | The list of attributes set for this memory region. | |
5787 | @end table | |
5788 | @end table | |
5789 | ||
5790 | ||
5791 | @subsection Attributes | |
5792 | ||
5793 | @subsubsection Memory Access Mode | |
5794 | The access mode attributes set whether @value{GDBN} may make read or | |
5795 | write accesses to a memory region. | |
5796 | ||
5797 | While these attributes prevent @value{GDBN} from performing invalid | |
5798 | memory accesses, they do nothing to prevent the target system, I/O DMA, | |
5799 | etc. from accessing memory. | |
5800 | ||
5801 | @table @code | |
5802 | @item ro | |
5803 | Memory is read only. | |
5804 | @item wo | |
5805 | Memory is write only. | |
5806 | @item rw | |
6ca652b0 | 5807 | Memory is read/write. This is the default. |
29e57380 C |
5808 | @end table |
5809 | ||
5810 | @subsubsection Memory Access Size | |
5811 | The acccess size attributes tells @value{GDBN} to use specific sized | |
5812 | accesses in the memory region. Often memory mapped device registers | |
5813 | require specific sized accesses. If no access size attribute is | |
5814 | specified, @value{GDBN} may use accesses of any size. | |
5815 | ||
5816 | @table @code | |
5817 | @item 8 | |
5818 | Use 8 bit memory accesses. | |
5819 | @item 16 | |
5820 | Use 16 bit memory accesses. | |
5821 | @item 32 | |
5822 | Use 32 bit memory accesses. | |
5823 | @item 64 | |
5824 | Use 64 bit memory accesses. | |
5825 | @end table | |
5826 | ||
5827 | @c @subsubsection Hardware/Software Breakpoints | |
5828 | @c The hardware/software breakpoint attributes set whether @value{GDBN} | |
5829 | @c will use hardware or software breakpoints for the internal breakpoints | |
5830 | @c used by the step, next, finish, until, etc. commands. | |
5831 | @c | |
5832 | @c @table @code | |
5833 | @c @item hwbreak | |
5834 | @c Always use hardware breakpoints | |
5835 | @c @item swbreak (default) | |
5836 | @c @end table | |
5837 | ||
5838 | @subsubsection Data Cache | |
5839 | The data cache attributes set whether @value{GDBN} will cache target | |
5840 | memory. While this generally improves performance by reducing debug | |
5841 | protocol overhead, it can lead to incorrect results because @value{GDBN} | |
5842 | does not know about volatile variables or memory mapped device | |
5843 | registers. | |
5844 | ||
5845 | @table @code | |
5846 | @item cache | |
5847 | Enable @value{GDBN} to cache target memory. | |
6ca652b0 EZ |
5848 | @item nocache |
5849 | Disable @value{GDBN} from caching target memory. This is the default. | |
29e57380 C |
5850 | @end table |
5851 | ||
5852 | @c @subsubsection Memory Write Verification | |
5853 | @c The memory write verification attributes set whether @value{GDBN} | |
5854 | @c will re-reads data after each write to verify the write was successful. | |
5855 | @c | |
5856 | @c @table @code | |
5857 | @c @item verify | |
5858 | @c @item noverify (default) | |
5859 | @c @end table | |
5860 | ||
16d9dec6 MS |
5861 | @node Dump/Restore Files |
5862 | @section Copy between memory and a file | |
5863 | @cindex dump/restore files | |
5864 | @cindex append data to a file | |
5865 | @cindex dump data to a file | |
5866 | @cindex restore data from a file | |
5867 | @kindex dump | |
5868 | @kindex append | |
5869 | @kindex restore | |
5870 | ||
5871 | The commands @code{dump}, @code{append}, and @code{restore} are used | |
5872 | for copying data between target memory and a file. Data is written | |
5873 | into a file using @code{dump} or @code{append}, and restored from a | |
5874 | file into memory by using @code{restore}. Files may be binary, srec, | |
5875 | intel hex, or tekhex (but only binary files can be appended). | |
5876 | ||
5877 | @table @code | |
5878 | @kindex dump binary | |
5879 | @kindex append binary | |
5880 | @item dump binary memory @var{filename} @var{start_addr} @var{end_addr} | |
5881 | Dump contents of memory from @var{start_addr} to @var{end_addr} into | |
5882 | raw binary format file @var{filename}. | |
5883 | ||
5884 | @item append binary memory @var{filename} @var{start_addr} @var{end_addr} | |
5885 | Append contents of memory from @var{start_addr} to @var{end_addr} to | |
5886 | raw binary format file @var{filename}. | |
5887 | ||
5888 | @item dump binary value @var{filename} @var{expression} | |
5889 | Dump value of @var{expression} into raw binary format file @var{filename}. | |
5890 | ||
5891 | @item append binary memory @var{filename} @var{expression} | |
5892 | Append value of @var{expression} to raw binary format file @var{filename}. | |
5893 | ||
5894 | @kindex dump ihex | |
5895 | @item dump ihex memory @var{filename} @var{start_addr} @var{end_addr} | |
5896 | Dump contents of memory from @var{start_addr} to @var{end_addr} into | |
5897 | intel hex format file @var{filename}. | |
5898 | ||
5899 | @item dump ihex value @var{filename} @var{expression} | |
5900 | Dump value of @var{expression} into intel hex format file @var{filename}. | |
5901 | ||
5902 | @kindex dump srec | |
5903 | @item dump srec memory @var{filename} @var{start_addr} @var{end_addr} | |
5904 | Dump contents of memory from @var{start_addr} to @var{end_addr} into | |
5905 | srec format file @var{filename}. | |
5906 | ||
5907 | @item dump srec value @var{filename} @var{expression} | |
5908 | Dump value of @var{expression} into srec format file @var{filename}. | |
5909 | ||
5910 | @kindex dump tekhex | |
5911 | @item dump tekhex memory @var{filename} @var{start_addr} @var{end_addr} | |
5912 | Dump contents of memory from @var{start_addr} to @var{end_addr} into | |
5913 | tekhex format file @var{filename}. | |
5914 | ||
5915 | @item dump tekhex value @var{filename} @var{expression} | |
5916 | Dump value of @var{expression} into tekhex format file @var{filename}. | |
5917 | ||
42f9b0a5 | 5918 | @item restore @var{filename} [@var{binary}] @var{bias} @var{start} @var{end} |
16d9dec6 MS |
5919 | Restore the contents of file @var{filename} into memory. The @code{restore} |
5920 | command can automatically recognize any known bfd file format, except for | |
5921 | raw binary. To restore a raw binary file you must use the optional argument | |
5922 | @var{binary} after the filename. | |
5923 | ||
5924 | If @var{bias} is non-zero, its value will be added to the addresses | |
5925 | contained in the file. Binary files always start at address zero, so | |
5926 | they will be restored at address @var{bias}. Other bfd files have | |
5927 | a built-in location; they will be restored at offset @var{bias} | |
5928 | from that location. | |
5929 | ||
5930 | If @var{start} and/or @var{end} are non-zero, then only data between | |
5931 | file offset @var{start} and file offset @var{end} will be restored. | |
5932 | These offsets are relative to the addresses in the file, before | |
5933 | the @var{bias} argument is applied. | |
5934 | ||
5935 | @end table | |
5936 | ||
a0eb71c5 KB |
5937 | @node Character Sets |
5938 | @section Character Sets | |
5939 | @cindex character sets | |
5940 | @cindex charset | |
5941 | @cindex translating between character sets | |
5942 | @cindex host character set | |
5943 | @cindex target character set | |
5944 | ||
5945 | If the program you are debugging uses a different character set to | |
5946 | represent characters and strings than the one @value{GDBN} uses itself, | |
5947 | @value{GDBN} can automatically translate between the character sets for | |
5948 | you. The character set @value{GDBN} uses we call the @dfn{host | |
5949 | character set}; the one the inferior program uses we call the | |
5950 | @dfn{target character set}. | |
5951 | ||
5952 | For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which | |
5953 | uses the ISO Latin 1 character set, but you are using @value{GDBN}'s | |
5954 | remote protocol (@pxref{Remote,Remote Debugging}) to debug a program | |
5955 | running on an IBM mainframe, which uses the @sc{ebcdic} character set, | |
5956 | then the host character set is Latin-1, and the target character set is | |
5957 | @sc{ebcdic}. If you give @value{GDBN} the command @code{set | |
5958 | target-charset ebcdic-us}, then @value{GDBN} translates between | |
5959 | @sc{ebcdic} and Latin 1 as you print character or string values, or use | |
5960 | character and string literals in expressions. | |
5961 | ||
5962 | @value{GDBN} has no way to automatically recognize which character set | |
5963 | the inferior program uses; you must tell it, using the @code{set | |
5964 | target-charset} command, described below. | |
5965 | ||
5966 | Here are the commands for controlling @value{GDBN}'s character set | |
5967 | support: | |
5968 | ||
5969 | @table @code | |
5970 | @item set target-charset @var{charset} | |
5971 | @kindex set target-charset | |
5972 | Set the current target character set to @var{charset}. We list the | |
5973 | character set names @value{GDBN} recognizes below, but if you invoke the | |
5974 | @code{set target-charset} command with no argument, @value{GDBN} lists | |
5975 | the character sets it supports. | |
5976 | @end table | |
5977 | ||
5978 | @table @code | |
5979 | @item set host-charset @var{charset} | |
5980 | @kindex set host-charset | |
5981 | Set the current host character set to @var{charset}. | |
5982 | ||
5983 | By default, @value{GDBN} uses a host character set appropriate to the | |
5984 | system it is running on; you can override that default using the | |
5985 | @code{set host-charset} command. | |
5986 | ||
5987 | @value{GDBN} can only use certain character sets as its host character | |
5988 | set. We list the character set names @value{GDBN} recognizes below, and | |
5989 | indicate which can be host character sets, but if you invoke the | |
5990 | @code{set host-charset} command with no argument, @value{GDBN} lists the | |
5991 | character sets it supports, placing an asterisk (@samp{*}) after those | |
5992 | it can use as a host character set. | |
5993 | ||
5994 | @item set charset @var{charset} | |
5995 | @kindex set charset | |
5996 | Set the current host and target character sets to @var{charset}. If you | |
5997 | invoke the @code{set charset} command with no argument, it lists the | |
5998 | character sets it supports. @value{GDBN} can only use certain character | |
5999 | sets as its host character set; it marks those in the list with an | |
6000 | asterisk (@samp{*}). | |
6001 | ||
6002 | @item show charset | |
6003 | @itemx show host-charset | |
6004 | @itemx show target-charset | |
6005 | @kindex show charset | |
6006 | @kindex show host-charset | |
6007 | @kindex show target-charset | |
6008 | Show the current host and target charsets. The @code{show host-charset} | |
6009 | and @code{show target-charset} commands are synonyms for @code{show | |
6010 | charset}. | |
6011 | ||
6012 | @end table | |
6013 | ||
6014 | @value{GDBN} currently includes support for the following character | |
6015 | sets: | |
6016 | ||
6017 | @table @code | |
6018 | ||
6019 | @item ASCII | |
6020 | @cindex ASCII character set | |
6021 | Seven-bit U.S. @sc{ascii}. @value{GDBN} can use this as its host | |
6022 | character set. | |
6023 | ||
6024 | @item ISO-8859-1 | |
6025 | @cindex ISO 8859-1 character set | |
6026 | @cindex ISO Latin 1 character set | |
6027 | The ISO Latin 1 character set. This extends ASCII with accented | |
6028 | characters needed for French, German, and Spanish. @value{GDBN} can use | |
6029 | this as its host character set. | |
6030 | ||
6031 | @item EBCDIC-US | |
6032 | @itemx IBM1047 | |
6033 | @cindex EBCDIC character set | |
6034 | @cindex IBM1047 character set | |
6035 | Variants of the @sc{ebcdic} character set, used on some of IBM's | |
6036 | mainframe operating systems. (@sc{gnu}/Linux on the S/390 uses U.S. @sc{ascii}.) | |
6037 | @value{GDBN} cannot use these as its host character set. | |
6038 | ||
6039 | @end table | |
6040 | ||
6041 | Note that these are all single-byte character sets. More work inside | |
6042 | GDB is needed to support multi-byte or variable-width character | |
6043 | encodings, like the UTF-8 and UCS-2 encodings of Unicode. | |
6044 | ||
6045 | Here is an example of @value{GDBN}'s character set support in action. | |
6046 | Assume that the following source code has been placed in the file | |
6047 | @file{charset-test.c}: | |
6048 | ||
6049 | @smallexample | |
6050 | #include <stdio.h> | |
6051 | ||
6052 | char ascii_hello[] | |
6053 | = @{72, 101, 108, 108, 111, 44, 32, 119, | |
6054 | 111, 114, 108, 100, 33, 10, 0@}; | |
6055 | char ibm1047_hello[] | |
6056 | = @{200, 133, 147, 147, 150, 107, 64, 166, | |
6057 | 150, 153, 147, 132, 90, 37, 0@}; | |
6058 | ||
6059 | main () | |
6060 | @{ | |
6061 | printf ("Hello, world!\n"); | |
6062 | @} | |
10998722 | 6063 | @end smallexample |
a0eb71c5 KB |
6064 | |
6065 | In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays | |
6066 | containing the string @samp{Hello, world!} followed by a newline, | |
6067 | encoded in the @sc{ascii} and @sc{ibm1047} character sets. | |
6068 | ||
6069 | We compile the program, and invoke the debugger on it: | |
6070 | ||
6071 | @smallexample | |
6072 | $ gcc -g charset-test.c -o charset-test | |
6073 | $ gdb -nw charset-test | |
6074 | GNU gdb 2001-12-19-cvs | |
6075 | Copyright 2001 Free Software Foundation, Inc. | |
6076 | @dots{} | |
6077 | (gdb) | |
10998722 | 6078 | @end smallexample |
a0eb71c5 KB |
6079 | |
6080 | We can use the @code{show charset} command to see what character sets | |
6081 | @value{GDBN} is currently using to interpret and display characters and | |
6082 | strings: | |
6083 | ||
6084 | @smallexample | |
6085 | (gdb) show charset | |
6086 | The current host and target character set is `iso-8859-1'. | |
6087 | (gdb) | |
10998722 | 6088 | @end smallexample |
a0eb71c5 KB |
6089 | |
6090 | For the sake of printing this manual, let's use @sc{ascii} as our | |
6091 | initial character set: | |
6092 | @smallexample | |
6093 | (gdb) set charset ascii | |
6094 | (gdb) show charset | |
6095 | The current host and target character set is `ascii'. | |
6096 | (gdb) | |
10998722 | 6097 | @end smallexample |
a0eb71c5 KB |
6098 | |
6099 | Let's assume that @sc{ascii} is indeed the correct character set for our | |
6100 | host system --- in other words, let's assume that if @value{GDBN} prints | |
6101 | characters using the @sc{ascii} character set, our terminal will display | |
6102 | them properly. Since our current target character set is also | |
6103 | @sc{ascii}, the contents of @code{ascii_hello} print legibly: | |
6104 | ||
6105 | @smallexample | |
6106 | (gdb) print ascii_hello | |
6107 | $1 = 0x401698 "Hello, world!\n" | |
6108 | (gdb) print ascii_hello[0] | |
6109 | $2 = 72 'H' | |
6110 | (gdb) | |
10998722 | 6111 | @end smallexample |
a0eb71c5 KB |
6112 | |
6113 | @value{GDBN} uses the target character set for character and string | |
6114 | literals you use in expressions: | |
6115 | ||
6116 | @smallexample | |
6117 | (gdb) print '+' | |
6118 | $3 = 43 '+' | |
6119 | (gdb) | |
10998722 | 6120 | @end smallexample |
a0eb71c5 KB |
6121 | |
6122 | The @sc{ascii} character set uses the number 43 to encode the @samp{+} | |
6123 | character. | |
6124 | ||
6125 | @value{GDBN} relies on the user to tell it which character set the | |
6126 | target program uses. If we print @code{ibm1047_hello} while our target | |
6127 | character set is still @sc{ascii}, we get jibberish: | |
6128 | ||
6129 | @smallexample | |
6130 | (gdb) print ibm1047_hello | |
6131 | $4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%" | |
6132 | (gdb) print ibm1047_hello[0] | |
6133 | $5 = 200 '\310' | |
6134 | (gdb) | |
10998722 | 6135 | @end smallexample |
a0eb71c5 KB |
6136 | |
6137 | If we invoke the @code{set target-charset} command without an argument, | |
6138 | @value{GDBN} tells us the character sets it supports: | |
6139 | ||
6140 | @smallexample | |
6141 | (gdb) set target-charset | |
6142 | Valid character sets are: | |
6143 | ascii * | |
6144 | iso-8859-1 * | |
6145 | ebcdic-us | |
6146 | ibm1047 | |
6147 | * - can be used as a host character set | |
10998722 | 6148 | @end smallexample |
a0eb71c5 KB |
6149 | |
6150 | We can select @sc{ibm1047} as our target character set, and examine the | |
6151 | program's strings again. Now the @sc{ascii} string is wrong, but | |
6152 | @value{GDBN} translates the contents of @code{ibm1047_hello} from the | |
6153 | target character set, @sc{ibm1047}, to the host character set, | |
6154 | @sc{ascii}, and they display correctly: | |
6155 | ||
6156 | @smallexample | |
6157 | (gdb) set target-charset ibm1047 | |
6158 | (gdb) show charset | |
6159 | The current host character set is `ascii'. | |
6160 | The current target character set is `ibm1047'. | |
6161 | (gdb) print ascii_hello | |
6162 | $6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012" | |
6163 | (gdb) print ascii_hello[0] | |
6164 | $7 = 72 '\110' | |
6165 | (gdb) print ibm1047_hello | |
6166 | $8 = 0x4016a8 "Hello, world!\n" | |
6167 | (gdb) print ibm1047_hello[0] | |
6168 | $9 = 200 'H' | |
6169 | (gdb) | |
10998722 | 6170 | @end smallexample |
a0eb71c5 KB |
6171 | |
6172 | As above, @value{GDBN} uses the target character set for character and | |
6173 | string literals you use in expressions: | |
6174 | ||
6175 | @smallexample | |
6176 | (gdb) print '+' | |
6177 | $10 = 78 '+' | |
6178 | (gdb) | |
10998722 | 6179 | @end smallexample |
a0eb71c5 KB |
6180 | |
6181 | The IBM1047 character set uses the number 78 to encode the @samp{+} | |
6182 | character. | |
6183 | ||
6184 | ||
e2e0bcd1 JB |
6185 | @node Macros |
6186 | @chapter C Preprocessor Macros | |
6187 | ||
6188 | Some languages, such as C and C++, provide a way to define and invoke | |
6189 | ``preprocessor macros'' which expand into strings of tokens. | |
6190 | @value{GDBN} can evaluate expressions containing macro invocations, show | |
6191 | the result of macro expansion, and show a macro's definition, including | |
6192 | where it was defined. | |
6193 | ||
6194 | You may need to compile your program specially to provide @value{GDBN} | |
6195 | with information about preprocessor macros. Most compilers do not | |
6196 | include macros in their debugging information, even when you compile | |
6197 | with the @option{-g} flag. @xref{Compilation}. | |
6198 | ||
6199 | A program may define a macro at one point, remove that definition later, | |
6200 | and then provide a different definition after that. Thus, at different | |
6201 | points in the program, a macro may have different definitions, or have | |
6202 | no definition at all. If there is a current stack frame, @value{GDBN} | |
6203 | uses the macros in scope at that frame's source code line. Otherwise, | |
6204 | @value{GDBN} uses the macros in scope at the current listing location; | |
6205 | see @ref{List}. | |
6206 | ||
6207 | At the moment, @value{GDBN} does not support the @code{##} | |
6208 | token-splicing operator, the @code{#} stringification operator, or | |
6209 | variable-arity macros. | |
6210 | ||
6211 | Whenever @value{GDBN} evaluates an expression, it always expands any | |
6212 | macro invocations present in the expression. @value{GDBN} also provides | |
6213 | the following commands for working with macros explicitly. | |
6214 | ||
6215 | @table @code | |
6216 | ||
6217 | @kindex macro expand | |
6218 | @cindex macro expansion, showing the results of preprocessor | |
6219 | @cindex preprocessor macro expansion, showing the results of | |
6220 | @cindex expanding preprocessor macros | |
6221 | @item macro expand @var{expression} | |
6222 | @itemx macro exp @var{expression} | |
6223 | Show the results of expanding all preprocessor macro invocations in | |
6224 | @var{expression}. Since @value{GDBN} simply expands macros, but does | |
6225 | not parse the result, @var{expression} need not be a valid expression; | |
6226 | it can be any string of tokens. | |
6227 | ||
6228 | @kindex macro expand-once | |
6229 | @item macro expand-once @var{expression} | |
6230 | @itemx macro exp1 @var{expression} | |
6231 | @i{(This command is not yet implemented.)} Show the results of | |
6232 | expanding those preprocessor macro invocations that appear explicitly in | |
6233 | @var{expression}. Macro invocations appearing in that expansion are | |
6234 | left unchanged. This command allows you to see the effect of a | |
6235 | particular macro more clearly, without being confused by further | |
6236 | expansions. Since @value{GDBN} simply expands macros, but does not | |
6237 | parse the result, @var{expression} need not be a valid expression; it | |
6238 | can be any string of tokens. | |
6239 | ||
475b0867 | 6240 | @kindex info macro |
e2e0bcd1 JB |
6241 | @cindex macro definition, showing |
6242 | @cindex definition, showing a macro's | |
475b0867 | 6243 | @item info macro @var{macro} |
e2e0bcd1 JB |
6244 | Show the definition of the macro named @var{macro}, and describe the |
6245 | source location where that definition was established. | |
6246 | ||
6247 | @kindex macro define | |
6248 | @cindex user-defined macros | |
6249 | @cindex defining macros interactively | |
6250 | @cindex macros, user-defined | |
6251 | @item macro define @var{macro} @var{replacement-list} | |
6252 | @itemx macro define @var{macro}(@var{arglist}) @var{replacement-list} | |
6253 | @i{(This command is not yet implemented.)} Introduce a definition for a | |
6254 | preprocessor macro named @var{macro}, invocations of which are replaced | |
6255 | by the tokens given in @var{replacement-list}. The first form of this | |
6256 | command defines an ``object-like'' macro, which takes no arguments; the | |
6257 | second form defines a ``function-like'' macro, which takes the arguments | |
6258 | given in @var{arglist}. | |
6259 | ||
6260 | A definition introduced by this command is in scope in every expression | |
6261 | evaluated in @value{GDBN}, until it is removed with the @command{macro | |
6262 | undef} command, described below. The definition overrides all | |
6263 | definitions for @var{macro} present in the program being debugged, as | |
6264 | well as any previous user-supplied definition. | |
6265 | ||
6266 | @kindex macro undef | |
6267 | @item macro undef @var{macro} | |
6268 | @i{(This command is not yet implemented.)} Remove any user-supplied | |
6269 | definition for the macro named @var{macro}. This command only affects | |
6270 | definitions provided with the @command{macro define} command, described | |
6271 | above; it cannot remove definitions present in the program being | |
6272 | debugged. | |
6273 | ||
6274 | @end table | |
6275 | ||
6276 | @cindex macros, example of debugging with | |
6277 | Here is a transcript showing the above commands in action. First, we | |
6278 | show our source files: | |
6279 | ||
6280 | @smallexample | |
6281 | $ cat sample.c | |
6282 | #include <stdio.h> | |
6283 | #include "sample.h" | |
6284 | ||
6285 | #define M 42 | |
6286 | #define ADD(x) (M + x) | |
6287 | ||
6288 | main () | |
6289 | @{ | |
6290 | #define N 28 | |
6291 | printf ("Hello, world!\n"); | |
6292 | #undef N | |
6293 | printf ("We're so creative.\n"); | |
6294 | #define N 1729 | |
6295 | printf ("Goodbye, world!\n"); | |
6296 | @} | |
6297 | $ cat sample.h | |
6298 | #define Q < | |
6299 | $ | |
6300 | @end smallexample | |
6301 | ||
6302 | Now, we compile the program using the @sc{gnu} C compiler, @value{NGCC}. | |
6303 | We pass the @option{-gdwarf-2} and @option{-g3} flags to ensure the | |
6304 | compiler includes information about preprocessor macros in the debugging | |
6305 | information. | |
6306 | ||
6307 | @smallexample | |
6308 | $ gcc -gdwarf-2 -g3 sample.c -o sample | |
6309 | $ | |
6310 | @end smallexample | |
6311 | ||
6312 | Now, we start @value{GDBN} on our sample program: | |
6313 | ||
6314 | @smallexample | |
6315 | $ gdb -nw sample | |
6316 | GNU gdb 2002-05-06-cvs | |
6317 | Copyright 2002 Free Software Foundation, Inc. | |
6318 | GDB is free software, @dots{} | |
6319 | (gdb) | |
6320 | @end smallexample | |
6321 | ||
6322 | We can expand macros and examine their definitions, even when the | |
6323 | program is not running. @value{GDBN} uses the current listing position | |
6324 | to decide which macro definitions are in scope: | |
6325 | ||
6326 | @smallexample | |
6327 | (gdb) list main | |
6328 | 3 | |
6329 | 4 #define M 42 | |
6330 | 5 #define ADD(x) (M + x) | |
6331 | 6 | |
6332 | 7 main () | |
6333 | 8 @{ | |
6334 | 9 #define N 28 | |
6335 | 10 printf ("Hello, world!\n"); | |
6336 | 11 #undef N | |
6337 | 12 printf ("We're so creative.\n"); | |
475b0867 | 6338 | (gdb) info macro ADD |
e2e0bcd1 JB |
6339 | Defined at /home/jimb/gdb/macros/play/sample.c:5 |
6340 | #define ADD(x) (M + x) | |
475b0867 | 6341 | (gdb) info macro Q |
e2e0bcd1 JB |
6342 | Defined at /home/jimb/gdb/macros/play/sample.h:1 |
6343 | included at /home/jimb/gdb/macros/play/sample.c:2 | |
6344 | #define Q < | |
6345 | (gdb) macro expand ADD(1) | |
6346 | expands to: (42 + 1) | |
6347 | (gdb) macro expand-once ADD(1) | |
6348 | expands to: once (M + 1) | |
6349 | (gdb) | |
6350 | @end smallexample | |
6351 | ||
6352 | In the example above, note that @command{macro expand-once} expands only | |
6353 | the macro invocation explicit in the original text --- the invocation of | |
6354 | @code{ADD} --- but does not expand the invocation of the macro @code{M}, | |
6355 | which was introduced by @code{ADD}. | |
6356 | ||
6357 | Once the program is running, GDB uses the macro definitions in force at | |
6358 | the source line of the current stack frame: | |
6359 | ||
6360 | @smallexample | |
6361 | (gdb) break main | |
6362 | Breakpoint 1 at 0x8048370: file sample.c, line 10. | |
6363 | (gdb) run | |
6364 | Starting program: /home/jimb/gdb/macros/play/sample | |
6365 | ||
6366 | Breakpoint 1, main () at sample.c:10 | |
6367 | 10 printf ("Hello, world!\n"); | |
6368 | (gdb) | |
6369 | @end smallexample | |
6370 | ||
6371 | At line 10, the definition of the macro @code{N} at line 9 is in force: | |
6372 | ||
6373 | @smallexample | |
475b0867 | 6374 | (gdb) info macro N |
e2e0bcd1 JB |
6375 | Defined at /home/jimb/gdb/macros/play/sample.c:9 |
6376 | #define N 28 | |
6377 | (gdb) macro expand N Q M | |
6378 | expands to: 28 < 42 | |
6379 | (gdb) print N Q M | |
6380 | $1 = 1 | |
6381 | (gdb) | |
6382 | @end smallexample | |
6383 | ||
6384 | As we step over directives that remove @code{N}'s definition, and then | |
6385 | give it a new definition, @value{GDBN} finds the definition (or lack | |
6386 | thereof) in force at each point: | |
6387 | ||
6388 | @smallexample | |
6389 | (gdb) next | |
6390 | Hello, world! | |
6391 | 12 printf ("We're so creative.\n"); | |
475b0867 | 6392 | (gdb) info macro N |
e2e0bcd1 JB |
6393 | The symbol `N' has no definition as a C/C++ preprocessor macro |
6394 | at /home/jimb/gdb/macros/play/sample.c:12 | |
6395 | (gdb) next | |
6396 | We're so creative. | |
6397 | 14 printf ("Goodbye, world!\n"); | |
475b0867 | 6398 | (gdb) info macro N |
e2e0bcd1 JB |
6399 | Defined at /home/jimb/gdb/macros/play/sample.c:13 |
6400 | #define N 1729 | |
6401 | (gdb) macro expand N Q M | |
6402 | expands to: 1729 < 42 | |
6403 | (gdb) print N Q M | |
6404 | $2 = 0 | |
6405 | (gdb) | |
6406 | @end smallexample | |
6407 | ||
6408 | ||
b37052ae EZ |
6409 | @node Tracepoints |
6410 | @chapter Tracepoints | |
6411 | @c This chapter is based on the documentation written by Michael | |
6412 | @c Snyder, David Taylor, Jim Blandy, and Elena Zannoni. | |
6413 | ||
6414 | @cindex tracepoints | |
6415 | In some applications, it is not feasible for the debugger to interrupt | |
6416 | the program's execution long enough for the developer to learn | |
6417 | anything helpful about its behavior. If the program's correctness | |
6418 | depends on its real-time behavior, delays introduced by a debugger | |
6419 | might cause the program to change its behavior drastically, or perhaps | |
6420 | fail, even when the code itself is correct. It is useful to be able | |
6421 | to observe the program's behavior without interrupting it. | |
6422 | ||
6423 | Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can | |
6424 | specify locations in the program, called @dfn{tracepoints}, and | |
6425 | arbitrary expressions to evaluate when those tracepoints are reached. | |
6426 | Later, using the @code{tfind} command, you can examine the values | |
6427 | those expressions had when the program hit the tracepoints. The | |
6428 | expressions may also denote objects in memory---structures or arrays, | |
6429 | for example---whose values @value{GDBN} should record; while visiting | |
6430 | a particular tracepoint, you may inspect those objects as if they were | |
6431 | in memory at that moment. However, because @value{GDBN} records these | |
6432 | values without interacting with you, it can do so quickly and | |
6433 | unobtrusively, hopefully not disturbing the program's behavior. | |
6434 | ||
6435 | The tracepoint facility is currently available only for remote | |
2c0069bb EZ |
6436 | targets. @xref{Targets}. In addition, your remote target must know how |
6437 | to collect trace data. This functionality is implemented in the remote | |
6438 | stub; however, none of the stubs distributed with @value{GDBN} support | |
6439 | tracepoints as of this writing. | |
b37052ae EZ |
6440 | |
6441 | This chapter describes the tracepoint commands and features. | |
6442 | ||
6443 | @menu | |
6444 | * Set Tracepoints:: | |
6445 | * Analyze Collected Data:: | |
6446 | * Tracepoint Variables:: | |
6447 | @end menu | |
6448 | ||
6449 | @node Set Tracepoints | |
6450 | @section Commands to Set Tracepoints | |
6451 | ||
6452 | Before running such a @dfn{trace experiment}, an arbitrary number of | |
6453 | tracepoints can be set. Like a breakpoint (@pxref{Set Breaks}), a | |
6454 | tracepoint has a number assigned to it by @value{GDBN}. Like with | |
6455 | breakpoints, tracepoint numbers are successive integers starting from | |
6456 | one. Many of the commands associated with tracepoints take the | |
6457 | tracepoint number as their argument, to identify which tracepoint to | |
6458 | work on. | |
6459 | ||
6460 | For each tracepoint, you can specify, in advance, some arbitrary set | |
6461 | of data that you want the target to collect in the trace buffer when | |
6462 | it hits that tracepoint. The collected data can include registers, | |
6463 | local variables, or global data. Later, you can use @value{GDBN} | |
6464 | commands to examine the values these data had at the time the | |
6465 | tracepoint was hit. | |
6466 | ||
6467 | This section describes commands to set tracepoints and associated | |
6468 | conditions and actions. | |
6469 | ||
6470 | @menu | |
6471 | * Create and Delete Tracepoints:: | |
6472 | * Enable and Disable Tracepoints:: | |
6473 | * Tracepoint Passcounts:: | |
6474 | * Tracepoint Actions:: | |
6475 | * Listing Tracepoints:: | |
6476 | * Starting and Stopping Trace Experiment:: | |
6477 | @end menu | |
6478 | ||
6479 | @node Create and Delete Tracepoints | |
6480 | @subsection Create and Delete Tracepoints | |
6481 | ||
6482 | @table @code | |
6483 | @cindex set tracepoint | |
6484 | @kindex trace | |
6485 | @item trace | |
6486 | The @code{trace} command is very similar to the @code{break} command. | |
6487 | Its argument can be a source line, a function name, or an address in | |
6488 | the target program. @xref{Set Breaks}. The @code{trace} command | |
6489 | defines a tracepoint, which is a point in the target program where the | |
6490 | debugger will briefly stop, collect some data, and then allow the | |
6491 | program to continue. Setting a tracepoint or changing its commands | |
6492 | doesn't take effect until the next @code{tstart} command; thus, you | |
6493 | cannot change the tracepoint attributes once a trace experiment is | |
6494 | running. | |
6495 | ||
6496 | Here are some examples of using the @code{trace} command: | |
6497 | ||
6498 | @smallexample | |
6499 | (@value{GDBP}) @b{trace foo.c:121} // a source file and line number | |
6500 | ||
6501 | (@value{GDBP}) @b{trace +2} // 2 lines forward | |
6502 | ||
6503 | (@value{GDBP}) @b{trace my_function} // first source line of function | |
6504 | ||
6505 | (@value{GDBP}) @b{trace *my_function} // EXACT start address of function | |
6506 | ||
6507 | (@value{GDBP}) @b{trace *0x2117c4} // an address | |
6508 | @end smallexample | |
6509 | ||
6510 | @noindent | |
6511 | You can abbreviate @code{trace} as @code{tr}. | |
6512 | ||
6513 | @vindex $tpnum | |
6514 | @cindex last tracepoint number | |
6515 | @cindex recent tracepoint number | |
6516 | @cindex tracepoint number | |
6517 | The convenience variable @code{$tpnum} records the tracepoint number | |
6518 | of the most recently set tracepoint. | |
6519 | ||
6520 | @kindex delete tracepoint | |
6521 | @cindex tracepoint deletion | |
6522 | @item delete tracepoint @r{[}@var{num}@r{]} | |
6523 | Permanently delete one or more tracepoints. With no argument, the | |
6524 | default is to delete all tracepoints. | |
6525 | ||
6526 | Examples: | |
6527 | ||
6528 | @smallexample | |
6529 | (@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints | |
6530 | ||
6531 | (@value{GDBP}) @b{delete trace} // remove all tracepoints | |
6532 | @end smallexample | |
6533 | ||
6534 | @noindent | |
6535 | You can abbreviate this command as @code{del tr}. | |
6536 | @end table | |
6537 | ||
6538 | @node Enable and Disable Tracepoints | |
6539 | @subsection Enable and Disable Tracepoints | |
6540 | ||
6541 | @table @code | |
6542 | @kindex disable tracepoint | |
6543 | @item disable tracepoint @r{[}@var{num}@r{]} | |
6544 | Disable tracepoint @var{num}, or all tracepoints if no argument | |
6545 | @var{num} is given. A disabled tracepoint will have no effect during | |
6546 | the next trace experiment, but it is not forgotten. You can re-enable | |
6547 | a disabled tracepoint using the @code{enable tracepoint} command. | |
6548 | ||
6549 | @kindex enable tracepoint | |
6550 | @item enable tracepoint @r{[}@var{num}@r{]} | |
6551 | Enable tracepoint @var{num}, or all tracepoints. The enabled | |
6552 | tracepoints will become effective the next time a trace experiment is | |
6553 | run. | |
6554 | @end table | |
6555 | ||
6556 | @node Tracepoint Passcounts | |
6557 | @subsection Tracepoint Passcounts | |
6558 | ||
6559 | @table @code | |
6560 | @kindex passcount | |
6561 | @cindex tracepoint pass count | |
6562 | @item passcount @r{[}@var{n} @r{[}@var{num}@r{]]} | |
6563 | Set the @dfn{passcount} of a tracepoint. The passcount is a way to | |
6564 | automatically stop a trace experiment. If a tracepoint's passcount is | |
6565 | @var{n}, then the trace experiment will be automatically stopped on | |
6566 | the @var{n}'th time that tracepoint is hit. If the tracepoint number | |
6567 | @var{num} is not specified, the @code{passcount} command sets the | |
6568 | passcount of the most recently defined tracepoint. If no passcount is | |
6569 | given, the trace experiment will run until stopped explicitly by the | |
6570 | user. | |
6571 | ||
6572 | Examples: | |
6573 | ||
6574 | @smallexample | |
6826cf00 EZ |
6575 | (@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of |
6576 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2} | |
b37052ae EZ |
6577 | |
6578 | (@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the | |
6826cf00 | 6579 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.} |
b37052ae EZ |
6580 | (@value{GDBP}) @b{trace foo} |
6581 | (@value{GDBP}) @b{pass 3} | |
6582 | (@value{GDBP}) @b{trace bar} | |
6583 | (@value{GDBP}) @b{pass 2} | |
6584 | (@value{GDBP}) @b{trace baz} | |
6585 | (@value{GDBP}) @b{pass 1} // Stop tracing when foo has been | |
6826cf00 EZ |
6586 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has} |
6587 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times} | |
6588 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.} | |
b37052ae EZ |
6589 | @end smallexample |
6590 | @end table | |
6591 | ||
6592 | @node Tracepoint Actions | |
6593 | @subsection Tracepoint Action Lists | |
6594 | ||
6595 | @table @code | |
6596 | @kindex actions | |
6597 | @cindex tracepoint actions | |
6598 | @item actions @r{[}@var{num}@r{]} | |
6599 | This command will prompt for a list of actions to be taken when the | |
6600 | tracepoint is hit. If the tracepoint number @var{num} is not | |
6601 | specified, this command sets the actions for the one that was most | |
6602 | recently defined (so that you can define a tracepoint and then say | |
6603 | @code{actions} without bothering about its number). You specify the | |
6604 | actions themselves on the following lines, one action at a time, and | |
6605 | terminate the actions list with a line containing just @code{end}. So | |
6606 | far, the only defined actions are @code{collect} and | |
6607 | @code{while-stepping}. | |
6608 | ||
6609 | @cindex remove actions from a tracepoint | |
6610 | To remove all actions from a tracepoint, type @samp{actions @var{num}} | |
6611 | and follow it immediately with @samp{end}. | |
6612 | ||
6613 | @smallexample | |
6614 | (@value{GDBP}) @b{collect @var{data}} // collect some data | |
6615 | ||
6826cf00 | 6616 | (@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data |
b37052ae | 6617 | |
6826cf00 | 6618 | (@value{GDBP}) @b{end} // signals the end of actions. |
b37052ae EZ |
6619 | @end smallexample |
6620 | ||
6621 | In the following example, the action list begins with @code{collect} | |
6622 | commands indicating the things to be collected when the tracepoint is | |
6623 | hit. Then, in order to single-step and collect additional data | |
6624 | following the tracepoint, a @code{while-stepping} command is used, | |
6625 | followed by the list of things to be collected while stepping. The | |
6626 | @code{while-stepping} command is terminated by its own separate | |
6627 | @code{end} command. Lastly, the action list is terminated by an | |
6628 | @code{end} command. | |
6629 | ||
6630 | @smallexample | |
6631 | (@value{GDBP}) @b{trace foo} | |
6632 | (@value{GDBP}) @b{actions} | |
6633 | Enter actions for tracepoint 1, one per line: | |
6634 | > collect bar,baz | |
6635 | > collect $regs | |
6636 | > while-stepping 12 | |
6637 | > collect $fp, $sp | |
6638 | > end | |
6639 | end | |
6640 | @end smallexample | |
6641 | ||
6642 | @kindex collect @r{(tracepoints)} | |
6643 | @item collect @var{expr1}, @var{expr2}, @dots{} | |
6644 | Collect values of the given expressions when the tracepoint is hit. | |
6645 | This command accepts a comma-separated list of any valid expressions. | |
6646 | In addition to global, static, or local variables, the following | |
6647 | special arguments are supported: | |
6648 | ||
6649 | @table @code | |
6650 | @item $regs | |
6651 | collect all registers | |
6652 | ||
6653 | @item $args | |
6654 | collect all function arguments | |
6655 | ||
6656 | @item $locals | |
6657 | collect all local variables. | |
6658 | @end table | |
6659 | ||
6660 | You can give several consecutive @code{collect} commands, each one | |
6661 | with a single argument, or one @code{collect} command with several | |
6662 | arguments separated by commas: the effect is the same. | |
6663 | ||
f5c37c66 EZ |
6664 | The command @code{info scope} (@pxref{Symbols, info scope}) is |
6665 | particularly useful for figuring out what data to collect. | |
6666 | ||
b37052ae EZ |
6667 | @kindex while-stepping @r{(tracepoints)} |
6668 | @item while-stepping @var{n} | |
6669 | Perform @var{n} single-step traces after the tracepoint, collecting | |
6670 | new data at each step. The @code{while-stepping} command is | |
6671 | followed by the list of what to collect while stepping (followed by | |
6672 | its own @code{end} command): | |
6673 | ||
6674 | @smallexample | |
6675 | > while-stepping 12 | |
6676 | > collect $regs, myglobal | |
6677 | > end | |
6678 | > | |
6679 | @end smallexample | |
6680 | ||
6681 | @noindent | |
6682 | You may abbreviate @code{while-stepping} as @code{ws} or | |
6683 | @code{stepping}. | |
6684 | @end table | |
6685 | ||
6686 | @node Listing Tracepoints | |
6687 | @subsection Listing Tracepoints | |
6688 | ||
6689 | @table @code | |
6690 | @kindex info tracepoints | |
6691 | @cindex information about tracepoints | |
6692 | @item info tracepoints @r{[}@var{num}@r{]} | |
8a037dd7 | 6693 | Display information about the tracepoint @var{num}. If you don't specify |
798c8bc6 | 6694 | a tracepoint number, displays information about all the tracepoints |
b37052ae EZ |
6695 | defined so far. For each tracepoint, the following information is |
6696 | shown: | |
6697 | ||
6698 | @itemize @bullet | |
6699 | @item | |
6700 | its number | |
6701 | @item | |
6702 | whether it is enabled or disabled | |
6703 | @item | |
6704 | its address | |
6705 | @item | |
6706 | its passcount as given by the @code{passcount @var{n}} command | |
6707 | @item | |
6708 | its step count as given by the @code{while-stepping @var{n}} command | |
6709 | @item | |
6710 | where in the source files is the tracepoint set | |
6711 | @item | |
6712 | its action list as given by the @code{actions} command | |
6713 | @end itemize | |
6714 | ||
6715 | @smallexample | |
6716 | (@value{GDBP}) @b{info trace} | |
6717 | Num Enb Address PassC StepC What | |
6718 | 1 y 0x002117c4 0 0 <gdb_asm> | |
6826cf00 EZ |
6719 | 2 y 0x0020dc64 0 0 in g_test at g_test.c:1375 |
6720 | 3 y 0x0020b1f4 0 0 in get_data at ../foo.c:41 | |
b37052ae EZ |
6721 | (@value{GDBP}) |
6722 | @end smallexample | |
6723 | ||
6724 | @noindent | |
6725 | This command can be abbreviated @code{info tp}. | |
6726 | @end table | |
6727 | ||
6728 | @node Starting and Stopping Trace Experiment | |
6729 | @subsection Starting and Stopping Trace Experiment | |
6730 | ||
6731 | @table @code | |
6732 | @kindex tstart | |
6733 | @cindex start a new trace experiment | |
6734 | @cindex collected data discarded | |
6735 | @item tstart | |
6736 | This command takes no arguments. It starts the trace experiment, and | |
6737 | begins collecting data. This has the side effect of discarding all | |
6738 | the data collected in the trace buffer during the previous trace | |
6739 | experiment. | |
6740 | ||
6741 | @kindex tstop | |
6742 | @cindex stop a running trace experiment | |
6743 | @item tstop | |
6744 | This command takes no arguments. It ends the trace experiment, and | |
6745 | stops collecting data. | |
6746 | ||
6747 | @strong{Note:} a trace experiment and data collection may stop | |
6748 | automatically if any tracepoint's passcount is reached | |
6749 | (@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full. | |
6750 | ||
6751 | @kindex tstatus | |
6752 | @cindex status of trace data collection | |
6753 | @cindex trace experiment, status of | |
6754 | @item tstatus | |
6755 | This command displays the status of the current trace data | |
6756 | collection. | |
6757 | @end table | |
6758 | ||
6759 | Here is an example of the commands we described so far: | |
6760 | ||
6761 | @smallexample | |
6762 | (@value{GDBP}) @b{trace gdb_c_test} | |
6763 | (@value{GDBP}) @b{actions} | |
6764 | Enter actions for tracepoint #1, one per line. | |
6765 | > collect $regs,$locals,$args | |
6766 | > while-stepping 11 | |
6767 | > collect $regs | |
6768 | > end | |
6769 | > end | |
6770 | (@value{GDBP}) @b{tstart} | |
6771 | [time passes @dots{}] | |
6772 | (@value{GDBP}) @b{tstop} | |
6773 | @end smallexample | |
6774 | ||
6775 | ||
6776 | @node Analyze Collected Data | |
6777 | @section Using the collected data | |
6778 | ||
6779 | After the tracepoint experiment ends, you use @value{GDBN} commands | |
6780 | for examining the trace data. The basic idea is that each tracepoint | |
6781 | collects a trace @dfn{snapshot} every time it is hit and another | |
6782 | snapshot every time it single-steps. All these snapshots are | |
6783 | consecutively numbered from zero and go into a buffer, and you can | |
6784 | examine them later. The way you examine them is to @dfn{focus} on a | |
6785 | specific trace snapshot. When the remote stub is focused on a trace | |
6786 | snapshot, it will respond to all @value{GDBN} requests for memory and | |
6787 | registers by reading from the buffer which belongs to that snapshot, | |
6788 | rather than from @emph{real} memory or registers of the program being | |
6789 | debugged. This means that @strong{all} @value{GDBN} commands | |
6790 | (@code{print}, @code{info registers}, @code{backtrace}, etc.) will | |
6791 | behave as if we were currently debugging the program state as it was | |
6792 | when the tracepoint occurred. Any requests for data that are not in | |
6793 | the buffer will fail. | |
6794 | ||
6795 | @menu | |
6796 | * tfind:: How to select a trace snapshot | |
6797 | * tdump:: How to display all data for a snapshot | |
6798 | * save-tracepoints:: How to save tracepoints for a future run | |
6799 | @end menu | |
6800 | ||
6801 | @node tfind | |
6802 | @subsection @code{tfind @var{n}} | |
6803 | ||
6804 | @kindex tfind | |
6805 | @cindex select trace snapshot | |
6806 | @cindex find trace snapshot | |
6807 | The basic command for selecting a trace snapshot from the buffer is | |
6808 | @code{tfind @var{n}}, which finds trace snapshot number @var{n}, | |
6809 | counting from zero. If no argument @var{n} is given, the next | |
6810 | snapshot is selected. | |
6811 | ||
6812 | Here are the various forms of using the @code{tfind} command. | |
6813 | ||
6814 | @table @code | |
6815 | @item tfind start | |
6816 | Find the first snapshot in the buffer. This is a synonym for | |
6817 | @code{tfind 0} (since 0 is the number of the first snapshot). | |
6818 | ||
6819 | @item tfind none | |
6820 | Stop debugging trace snapshots, resume @emph{live} debugging. | |
6821 | ||
6822 | @item tfind end | |
6823 | Same as @samp{tfind none}. | |
6824 | ||
6825 | @item tfind | |
6826 | No argument means find the next trace snapshot. | |
6827 | ||
6828 | @item tfind - | |
6829 | Find the previous trace snapshot before the current one. This permits | |
6830 | retracing earlier steps. | |
6831 | ||
6832 | @item tfind tracepoint @var{num} | |
6833 | Find the next snapshot associated with tracepoint @var{num}. Search | |
6834 | proceeds forward from the last examined trace snapshot. If no | |
6835 | argument @var{num} is given, it means find the next snapshot collected | |
6836 | for the same tracepoint as the current snapshot. | |
6837 | ||
6838 | @item tfind pc @var{addr} | |
6839 | Find the next snapshot associated with the value @var{addr} of the | |
6840 | program counter. Search proceeds forward from the last examined trace | |
6841 | snapshot. If no argument @var{addr} is given, it means find the next | |
6842 | snapshot with the same value of PC as the current snapshot. | |
6843 | ||
6844 | @item tfind outside @var{addr1}, @var{addr2} | |
6845 | Find the next snapshot whose PC is outside the given range of | |
6846 | addresses. | |
6847 | ||
6848 | @item tfind range @var{addr1}, @var{addr2} | |
6849 | Find the next snapshot whose PC is between @var{addr1} and | |
6850 | @var{addr2}. @c FIXME: Is the range inclusive or exclusive? | |
6851 | ||
6852 | @item tfind line @r{[}@var{file}:@r{]}@var{n} | |
6853 | Find the next snapshot associated with the source line @var{n}. If | |
6854 | the optional argument @var{file} is given, refer to line @var{n} in | |
6855 | that source file. Search proceeds forward from the last examined | |
6856 | trace snapshot. If no argument @var{n} is given, it means find the | |
6857 | next line other than the one currently being examined; thus saying | |
6858 | @code{tfind line} repeatedly can appear to have the same effect as | |
6859 | stepping from line to line in a @emph{live} debugging session. | |
6860 | @end table | |
6861 | ||
6862 | The default arguments for the @code{tfind} commands are specifically | |
6863 | designed to make it easy to scan through the trace buffer. For | |
6864 | instance, @code{tfind} with no argument selects the next trace | |
6865 | snapshot, and @code{tfind -} with no argument selects the previous | |
6866 | trace snapshot. So, by giving one @code{tfind} command, and then | |
6867 | simply hitting @key{RET} repeatedly you can examine all the trace | |
6868 | snapshots in order. Or, by saying @code{tfind -} and then hitting | |
6869 | @key{RET} repeatedly you can examine the snapshots in reverse order. | |
6870 | The @code{tfind line} command with no argument selects the snapshot | |
6871 | for the next source line executed. The @code{tfind pc} command with | |
6872 | no argument selects the next snapshot with the same program counter | |
6873 | (PC) as the current frame. The @code{tfind tracepoint} command with | |
6874 | no argument selects the next trace snapshot collected by the same | |
6875 | tracepoint as the current one. | |
6876 | ||
6877 | In addition to letting you scan through the trace buffer manually, | |
6878 | these commands make it easy to construct @value{GDBN} scripts that | |
6879 | scan through the trace buffer and print out whatever collected data | |
6880 | you are interested in. Thus, if we want to examine the PC, FP, and SP | |
6881 | registers from each trace frame in the buffer, we can say this: | |
6882 | ||
6883 | @smallexample | |
6884 | (@value{GDBP}) @b{tfind start} | |
6885 | (@value{GDBP}) @b{while ($trace_frame != -1)} | |
6886 | > printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \ | |
6887 | $trace_frame, $pc, $sp, $fp | |
6888 | > tfind | |
6889 | > end | |
6890 | ||
6891 | Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44 | |
6892 | Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44 | |
6893 | Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44 | |
6894 | Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44 | |
6895 | Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44 | |
6896 | Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44 | |
6897 | Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44 | |
6898 | Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44 | |
6899 | Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44 | |
6900 | Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44 | |
6901 | Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14 | |
6902 | @end smallexample | |
6903 | ||
6904 | Or, if we want to examine the variable @code{X} at each source line in | |
6905 | the buffer: | |
6906 | ||
6907 | @smallexample | |
6908 | (@value{GDBP}) @b{tfind start} | |
6909 | (@value{GDBP}) @b{while ($trace_frame != -1)} | |
6910 | > printf "Frame %d, X == %d\n", $trace_frame, X | |
6911 | > tfind line | |
6912 | > end | |
6913 | ||
6914 | Frame 0, X = 1 | |
6915 | Frame 7, X = 2 | |
6916 | Frame 13, X = 255 | |
6917 | @end smallexample | |
6918 | ||
6919 | @node tdump | |
6920 | @subsection @code{tdump} | |
6921 | @kindex tdump | |
6922 | @cindex dump all data collected at tracepoint | |
6923 | @cindex tracepoint data, display | |
6924 | ||
6925 | This command takes no arguments. It prints all the data collected at | |
6926 | the current trace snapshot. | |
6927 | ||
6928 | @smallexample | |
6929 | (@value{GDBP}) @b{trace 444} | |
6930 | (@value{GDBP}) @b{actions} | |
6931 | Enter actions for tracepoint #2, one per line: | |
6932 | > collect $regs, $locals, $args, gdb_long_test | |
6933 | > end | |
6934 | ||
6935 | (@value{GDBP}) @b{tstart} | |
6936 | ||
6937 | (@value{GDBP}) @b{tfind line 444} | |
6938 | #0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66) | |
6939 | at gdb_test.c:444 | |
6940 | 444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", ) | |
6941 | ||
6942 | (@value{GDBP}) @b{tdump} | |
6943 | Data collected at tracepoint 2, trace frame 1: | |
6944 | d0 0xc4aa0085 -995491707 | |
6945 | d1 0x18 24 | |
6946 | d2 0x80 128 | |
6947 | d3 0x33 51 | |
6948 | d4 0x71aea3d 119204413 | |
6949 | d5 0x22 34 | |
6950 | d6 0xe0 224 | |
6951 | d7 0x380035 3670069 | |
6952 | a0 0x19e24a 1696330 | |
6953 | a1 0x3000668 50333288 | |
6954 | a2 0x100 256 | |
6955 | a3 0x322000 3284992 | |
6956 | a4 0x3000698 50333336 | |
6957 | a5 0x1ad3cc 1758156 | |
6958 | fp 0x30bf3c 0x30bf3c | |
6959 | sp 0x30bf34 0x30bf34 | |
6960 | ps 0x0 0 | |
6961 | pc 0x20b2c8 0x20b2c8 | |
6962 | fpcontrol 0x0 0 | |
6963 | fpstatus 0x0 0 | |
6964 | fpiaddr 0x0 0 | |
6965 | p = 0x20e5b4 "gdb-test" | |
6966 | p1 = (void *) 0x11 | |
6967 | p2 = (void *) 0x22 | |
6968 | p3 = (void *) 0x33 | |
6969 | p4 = (void *) 0x44 | |
6970 | p5 = (void *) 0x55 | |
6971 | p6 = (void *) 0x66 | |
6972 | gdb_long_test = 17 '\021' | |
6973 | ||
6974 | (@value{GDBP}) | |
6975 | @end smallexample | |
6976 | ||
6977 | @node save-tracepoints | |
6978 | @subsection @code{save-tracepoints @var{filename}} | |
6979 | @kindex save-tracepoints | |
6980 | @cindex save tracepoints for future sessions | |
6981 | ||
6982 | This command saves all current tracepoint definitions together with | |
6983 | their actions and passcounts, into a file @file{@var{filename}} | |
6984 | suitable for use in a later debugging session. To read the saved | |
6985 | tracepoint definitions, use the @code{source} command (@pxref{Command | |
6986 | Files}). | |
6987 | ||
6988 | @node Tracepoint Variables | |
6989 | @section Convenience Variables for Tracepoints | |
6990 | @cindex tracepoint variables | |
6991 | @cindex convenience variables for tracepoints | |
6992 | ||
6993 | @table @code | |
6994 | @vindex $trace_frame | |
6995 | @item (int) $trace_frame | |
6996 | The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no | |
6997 | snapshot is selected. | |
6998 | ||
6999 | @vindex $tracepoint | |
7000 | @item (int) $tracepoint | |
7001 | The tracepoint for the current trace snapshot. | |
7002 | ||
7003 | @vindex $trace_line | |
7004 | @item (int) $trace_line | |
7005 | The line number for the current trace snapshot. | |
7006 | ||
7007 | @vindex $trace_file | |
7008 | @item (char []) $trace_file | |
7009 | The source file for the current trace snapshot. | |
7010 | ||
7011 | @vindex $trace_func | |
7012 | @item (char []) $trace_func | |
7013 | The name of the function containing @code{$tracepoint}. | |
7014 | @end table | |
7015 | ||
7016 | Note: @code{$trace_file} is not suitable for use in @code{printf}, | |
7017 | use @code{output} instead. | |
7018 | ||
7019 | Here's a simple example of using these convenience variables for | |
7020 | stepping through all the trace snapshots and printing some of their | |
7021 | data. | |
7022 | ||
7023 | @smallexample | |
7024 | (@value{GDBP}) @b{tfind start} | |
7025 | ||
7026 | (@value{GDBP}) @b{while $trace_frame != -1} | |
7027 | > output $trace_file | |
7028 | > printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint | |
7029 | > tfind | |
7030 | > end | |
7031 | @end smallexample | |
7032 | ||
df0cd8c5 JB |
7033 | @node Overlays |
7034 | @chapter Debugging Programs That Use Overlays | |
7035 | @cindex overlays | |
7036 | ||
7037 | If your program is too large to fit completely in your target system's | |
7038 | memory, you can sometimes use @dfn{overlays} to work around this | |
7039 | problem. @value{GDBN} provides some support for debugging programs that | |
7040 | use overlays. | |
7041 | ||
7042 | @menu | |
7043 | * How Overlays Work:: A general explanation of overlays. | |
7044 | * Overlay Commands:: Managing overlays in @value{GDBN}. | |
7045 | * Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are | |
7046 | mapped by asking the inferior. | |
7047 | * Overlay Sample Program:: A sample program using overlays. | |
7048 | @end menu | |
7049 | ||
7050 | @node How Overlays Work | |
7051 | @section How Overlays Work | |
7052 | @cindex mapped overlays | |
7053 | @cindex unmapped overlays | |
7054 | @cindex load address, overlay's | |
7055 | @cindex mapped address | |
7056 | @cindex overlay area | |
7057 | ||
7058 | Suppose you have a computer whose instruction address space is only 64 | |
7059 | kilobytes long, but which has much more memory which can be accessed by | |
7060 | other means: special instructions, segment registers, or memory | |
7061 | management hardware, for example. Suppose further that you want to | |
7062 | adapt a program which is larger than 64 kilobytes to run on this system. | |
7063 | ||
7064 | One solution is to identify modules of your program which are relatively | |
7065 | independent, and need not call each other directly; call these modules | |
7066 | @dfn{overlays}. Separate the overlays from the main program, and place | |
7067 | their machine code in the larger memory. Place your main program in | |
7068 | instruction memory, but leave at least enough space there to hold the | |
7069 | largest overlay as well. | |
7070 | ||
7071 | Now, to call a function located in an overlay, you must first copy that | |
7072 | overlay's machine code from the large memory into the space set aside | |
7073 | for it in the instruction memory, and then jump to its entry point | |
7074 | there. | |
7075 | ||
c928edc0 AC |
7076 | @c NB: In the below the mapped area's size is greater or equal to the |
7077 | @c size of all overlays. This is intentional to remind the developer | |
7078 | @c that overlays don't necessarily need to be the same size. | |
7079 | ||
474c8240 | 7080 | @smallexample |
df0cd8c5 | 7081 | @group |
c928edc0 AC |
7082 | Data Instruction Larger |
7083 | Address Space Address Space Address Space | |
7084 | +-----------+ +-----------+ +-----------+ | |
7085 | | | | | | | | |
7086 | +-----------+ +-----------+ +-----------+<-- overlay 1 | |
7087 | | program | | main | .----| overlay 1 | load address | |
7088 | | variables | | program | | +-----------+ | |
7089 | | and heap | | | | | | | |
7090 | +-----------+ | | | +-----------+<-- overlay 2 | |
7091 | | | +-----------+ | | | load address | |
7092 | +-----------+ | | | .-| overlay 2 | | |
7093 | | | | | | | | |
7094 | mapped --->+-----------+ | | +-----------+ | |
7095 | address | | | | | | | |
7096 | | overlay | <-' | | | | |
7097 | | area | <---' +-----------+<-- overlay 3 | |
7098 | | | <---. | | load address | |
7099 | +-----------+ `--| overlay 3 | | |
7100 | | | | | | |
7101 | +-----------+ | | | |
7102 | +-----------+ | |
7103 | | | | |
7104 | +-----------+ | |
7105 | ||
7106 | @anchor{A code overlay}A code overlay | |
df0cd8c5 | 7107 | @end group |
474c8240 | 7108 | @end smallexample |
df0cd8c5 | 7109 | |
c928edc0 AC |
7110 | The diagram (@pxref{A code overlay}) shows a system with separate data |
7111 | and instruction address spaces. To map an overlay, the program copies | |
7112 | its code from the larger address space to the instruction address space. | |
7113 | Since the overlays shown here all use the same mapped address, only one | |
7114 | may be mapped at a time. For a system with a single address space for | |
7115 | data and instructions, the diagram would be similar, except that the | |
7116 | program variables and heap would share an address space with the main | |
7117 | program and the overlay area. | |
df0cd8c5 JB |
7118 | |
7119 | An overlay loaded into instruction memory and ready for use is called a | |
7120 | @dfn{mapped} overlay; its @dfn{mapped address} is its address in the | |
7121 | instruction memory. An overlay not present (or only partially present) | |
7122 | in instruction memory is called @dfn{unmapped}; its @dfn{load address} | |
7123 | is its address in the larger memory. The mapped address is also called | |
7124 | the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also | |
7125 | called the @dfn{load memory address}, or @dfn{LMA}. | |
7126 | ||
7127 | Unfortunately, overlays are not a completely transparent way to adapt a | |
7128 | program to limited instruction memory. They introduce a new set of | |
7129 | global constraints you must keep in mind as you design your program: | |
7130 | ||
7131 | @itemize @bullet | |
7132 | ||
7133 | @item | |
7134 | Before calling or returning to a function in an overlay, your program | |
7135 | must make sure that overlay is actually mapped. Otherwise, the call or | |
7136 | return will transfer control to the right address, but in the wrong | |
7137 | overlay, and your program will probably crash. | |
7138 | ||
7139 | @item | |
7140 | If the process of mapping an overlay is expensive on your system, you | |
7141 | will need to choose your overlays carefully to minimize their effect on | |
7142 | your program's performance. | |
7143 | ||
7144 | @item | |
7145 | The executable file you load onto your system must contain each | |
7146 | overlay's instructions, appearing at the overlay's load address, not its | |
7147 | mapped address. However, each overlay's instructions must be relocated | |
7148 | and its symbols defined as if the overlay were at its mapped address. | |
7149 | You can use GNU linker scripts to specify different load and relocation | |
7150 | addresses for pieces of your program; see @ref{Overlay Description,,, | |
7151 | ld.info, Using ld: the GNU linker}. | |
7152 | ||
7153 | @item | |
7154 | The procedure for loading executable files onto your system must be able | |
7155 | to load their contents into the larger address space as well as the | |
7156 | instruction and data spaces. | |
7157 | ||
7158 | @end itemize | |
7159 | ||
7160 | The overlay system described above is rather simple, and could be | |
7161 | improved in many ways: | |
7162 | ||
7163 | @itemize @bullet | |
7164 | ||
7165 | @item | |
7166 | If your system has suitable bank switch registers or memory management | |
7167 | hardware, you could use those facilities to make an overlay's load area | |
7168 | contents simply appear at their mapped address in instruction space. | |
7169 | This would probably be faster than copying the overlay to its mapped | |
7170 | area in the usual way. | |
7171 | ||
7172 | @item | |
7173 | If your overlays are small enough, you could set aside more than one | |
7174 | overlay area, and have more than one overlay mapped at a time. | |
7175 | ||
7176 | @item | |
7177 | You can use overlays to manage data, as well as instructions. In | |
7178 | general, data overlays are even less transparent to your design than | |
7179 | code overlays: whereas code overlays only require care when you call or | |
7180 | return to functions, data overlays require care every time you access | |
7181 | the data. Also, if you change the contents of a data overlay, you | |
7182 | must copy its contents back out to its load address before you can copy a | |
7183 | different data overlay into the same mapped area. | |
7184 | ||
7185 | @end itemize | |
7186 | ||
7187 | ||
7188 | @node Overlay Commands | |
7189 | @section Overlay Commands | |
7190 | ||
7191 | To use @value{GDBN}'s overlay support, each overlay in your program must | |
7192 | correspond to a separate section of the executable file. The section's | |
7193 | virtual memory address and load memory address must be the overlay's | |
7194 | mapped and load addresses. Identifying overlays with sections allows | |
7195 | @value{GDBN} to determine the appropriate address of a function or | |
7196 | variable, depending on whether the overlay is mapped or not. | |
7197 | ||
7198 | @value{GDBN}'s overlay commands all start with the word @code{overlay}; | |
7199 | you can abbreviate this as @code{ov} or @code{ovly}. The commands are: | |
7200 | ||
7201 | @table @code | |
7202 | @item overlay off | |
7203 | @kindex overlay off | |
7204 | Disable @value{GDBN}'s overlay support. When overlay support is | |
7205 | disabled, @value{GDBN} assumes that all functions and variables are | |
7206 | always present at their mapped addresses. By default, @value{GDBN}'s | |
7207 | overlay support is disabled. | |
7208 | ||
7209 | @item overlay manual | |
7210 | @kindex overlay manual | |
7211 | @cindex manual overlay debugging | |
7212 | Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN} | |
7213 | relies on you to tell it which overlays are mapped, and which are not, | |
7214 | using the @code{overlay map-overlay} and @code{overlay unmap-overlay} | |
7215 | commands described below. | |
7216 | ||
7217 | @item overlay map-overlay @var{overlay} | |
7218 | @itemx overlay map @var{overlay} | |
7219 | @kindex overlay map-overlay | |
7220 | @cindex map an overlay | |
7221 | Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must | |
7222 | be the name of the object file section containing the overlay. When an | |
7223 | overlay is mapped, @value{GDBN} assumes it can find the overlay's | |
7224 | functions and variables at their mapped addresses. @value{GDBN} assumes | |
7225 | that any other overlays whose mapped ranges overlap that of | |
7226 | @var{overlay} are now unmapped. | |
7227 | ||
7228 | @item overlay unmap-overlay @var{overlay} | |
7229 | @itemx overlay unmap @var{overlay} | |
7230 | @kindex overlay unmap-overlay | |
7231 | @cindex unmap an overlay | |
7232 | Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay} | |
7233 | must be the name of the object file section containing the overlay. | |
7234 | When an overlay is unmapped, @value{GDBN} assumes it can find the | |
7235 | overlay's functions and variables at their load addresses. | |
7236 | ||
7237 | @item overlay auto | |
7238 | @kindex overlay auto | |
7239 | Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN} | |
7240 | consults a data structure the overlay manager maintains in the inferior | |
7241 | to see which overlays are mapped. For details, see @ref{Automatic | |
7242 | Overlay Debugging}. | |
7243 | ||
7244 | @item overlay load-target | |
7245 | @itemx overlay load | |
7246 | @kindex overlay load-target | |
7247 | @cindex reloading the overlay table | |
7248 | Re-read the overlay table from the inferior. Normally, @value{GDBN} | |
7249 | re-reads the table @value{GDBN} automatically each time the inferior | |
7250 | stops, so this command should only be necessary if you have changed the | |
7251 | overlay mapping yourself using @value{GDBN}. This command is only | |
7252 | useful when using automatic overlay debugging. | |
7253 | ||
7254 | @item overlay list-overlays | |
7255 | @itemx overlay list | |
7256 | @cindex listing mapped overlays | |
7257 | Display a list of the overlays currently mapped, along with their mapped | |
7258 | addresses, load addresses, and sizes. | |
7259 | ||
7260 | @end table | |
7261 | ||
7262 | Normally, when @value{GDBN} prints a code address, it includes the name | |
7263 | of the function the address falls in: | |
7264 | ||
474c8240 | 7265 | @smallexample |
df0cd8c5 JB |
7266 | (gdb) print main |
7267 | $3 = @{int ()@} 0x11a0 <main> | |
474c8240 | 7268 | @end smallexample |
df0cd8c5 JB |
7269 | @noindent |
7270 | When overlay debugging is enabled, @value{GDBN} recognizes code in | |
7271 | unmapped overlays, and prints the names of unmapped functions with | |
7272 | asterisks around them. For example, if @code{foo} is a function in an | |
7273 | unmapped overlay, @value{GDBN} prints it this way: | |
7274 | ||
474c8240 | 7275 | @smallexample |
df0cd8c5 JB |
7276 | (gdb) overlay list |
7277 | No sections are mapped. | |
7278 | (gdb) print foo | |
7279 | $5 = @{int (int)@} 0x100000 <*foo*> | |
474c8240 | 7280 | @end smallexample |
df0cd8c5 JB |
7281 | @noindent |
7282 | When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's | |
7283 | name normally: | |
7284 | ||
474c8240 | 7285 | @smallexample |
df0cd8c5 JB |
7286 | (gdb) overlay list |
7287 | Section .ov.foo.text, loaded at 0x100000 - 0x100034, | |
7288 | mapped at 0x1016 - 0x104a | |
7289 | (gdb) print foo | |
7290 | $6 = @{int (int)@} 0x1016 <foo> | |
474c8240 | 7291 | @end smallexample |
df0cd8c5 JB |
7292 | |
7293 | When overlay debugging is enabled, @value{GDBN} can find the correct | |
7294 | address for functions and variables in an overlay, whether or not the | |
7295 | overlay is mapped. This allows most @value{GDBN} commands, like | |
7296 | @code{break} and @code{disassemble}, to work normally, even on unmapped | |
7297 | code. However, @value{GDBN}'s breakpoint support has some limitations: | |
7298 | ||
7299 | @itemize @bullet | |
7300 | @item | |
7301 | @cindex breakpoints in overlays | |
7302 | @cindex overlays, setting breakpoints in | |
7303 | You can set breakpoints in functions in unmapped overlays, as long as | |
7304 | @value{GDBN} can write to the overlay at its load address. | |
7305 | @item | |
7306 | @value{GDBN} can not set hardware or simulator-based breakpoints in | |
7307 | unmapped overlays. However, if you set a breakpoint at the end of your | |
7308 | overlay manager (and tell @value{GDBN} which overlays are now mapped, if | |
7309 | you are using manual overlay management), @value{GDBN} will re-set its | |
7310 | breakpoints properly. | |
7311 | @end itemize | |
7312 | ||
7313 | ||
7314 | @node Automatic Overlay Debugging | |
7315 | @section Automatic Overlay Debugging | |
7316 | @cindex automatic overlay debugging | |
7317 | ||
7318 | @value{GDBN} can automatically track which overlays are mapped and which | |
7319 | are not, given some simple co-operation from the overlay manager in the | |
7320 | inferior. If you enable automatic overlay debugging with the | |
7321 | @code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN} | |
7322 | looks in the inferior's memory for certain variables describing the | |
7323 | current state of the overlays. | |
7324 | ||
7325 | Here are the variables your overlay manager must define to support | |
7326 | @value{GDBN}'s automatic overlay debugging: | |
7327 | ||
7328 | @table @asis | |
7329 | ||
7330 | @item @code{_ovly_table}: | |
7331 | This variable must be an array of the following structures: | |
7332 | ||
474c8240 | 7333 | @smallexample |
df0cd8c5 JB |
7334 | struct |
7335 | @{ | |
7336 | /* The overlay's mapped address. */ | |
7337 | unsigned long vma; | |
7338 | ||
7339 | /* The size of the overlay, in bytes. */ | |
7340 | unsigned long size; | |
7341 | ||
7342 | /* The overlay's load address. */ | |
7343 | unsigned long lma; | |
7344 | ||
7345 | /* Non-zero if the overlay is currently mapped; | |
7346 | zero otherwise. */ | |
7347 | unsigned long mapped; | |
7348 | @} | |
474c8240 | 7349 | @end smallexample |
df0cd8c5 JB |
7350 | |
7351 | @item @code{_novlys}: | |
7352 | This variable must be a four-byte signed integer, holding the total | |
7353 | number of elements in @code{_ovly_table}. | |
7354 | ||
7355 | @end table | |
7356 | ||
7357 | To decide whether a particular overlay is mapped or not, @value{GDBN} | |
7358 | looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and | |
7359 | @code{lma} members equal the VMA and LMA of the overlay's section in the | |
7360 | executable file. When @value{GDBN} finds a matching entry, it consults | |
7361 | the entry's @code{mapped} member to determine whether the overlay is | |
7362 | currently mapped. | |
7363 | ||
81d46470 | 7364 | In addition, your overlay manager may define a function called |
def71bfa | 7365 | @code{_ovly_debug_event}. If this function is defined, @value{GDBN} |
81d46470 MS |
7366 | will silently set a breakpoint there. If the overlay manager then |
7367 | calls this function whenever it has changed the overlay table, this | |
7368 | will enable @value{GDBN} to accurately keep track of which overlays | |
7369 | are in program memory, and update any breakpoints that may be set | |
7370 | in overlays. This will allow breakpoints to work even if the | |
7371 | overlays are kept in ROM or other non-writable memory while they | |
7372 | are not being executed. | |
df0cd8c5 JB |
7373 | |
7374 | @node Overlay Sample Program | |
7375 | @section Overlay Sample Program | |
7376 | @cindex overlay example program | |
7377 | ||
7378 | When linking a program which uses overlays, you must place the overlays | |
7379 | at their load addresses, while relocating them to run at their mapped | |
7380 | addresses. To do this, you must write a linker script (@pxref{Overlay | |
7381 | Description,,, ld.info, Using ld: the GNU linker}). Unfortunately, | |
7382 | since linker scripts are specific to a particular host system, target | |
7383 | architecture, and target memory layout, this manual cannot provide | |
7384 | portable sample code demonstrating @value{GDBN}'s overlay support. | |
7385 | ||
7386 | However, the @value{GDBN} source distribution does contain an overlaid | |
7387 | program, with linker scripts for a few systems, as part of its test | |
7388 | suite. The program consists of the following files from | |
7389 | @file{gdb/testsuite/gdb.base}: | |
7390 | ||
7391 | @table @file | |
7392 | @item overlays.c | |
7393 | The main program file. | |
7394 | @item ovlymgr.c | |
7395 | A simple overlay manager, used by @file{overlays.c}. | |
7396 | @item foo.c | |
7397 | @itemx bar.c | |
7398 | @itemx baz.c | |
7399 | @itemx grbx.c | |
7400 | Overlay modules, loaded and used by @file{overlays.c}. | |
7401 | @item d10v.ld | |
7402 | @itemx m32r.ld | |
7403 | Linker scripts for linking the test program on the @code{d10v-elf} | |
7404 | and @code{m32r-elf} targets. | |
7405 | @end table | |
7406 | ||
7407 | You can build the test program using the @code{d10v-elf} GCC | |
7408 | cross-compiler like this: | |
7409 | ||
474c8240 | 7410 | @smallexample |
df0cd8c5 JB |
7411 | $ d10v-elf-gcc -g -c overlays.c |
7412 | $ d10v-elf-gcc -g -c ovlymgr.c | |
7413 | $ d10v-elf-gcc -g -c foo.c | |
7414 | $ d10v-elf-gcc -g -c bar.c | |
7415 | $ d10v-elf-gcc -g -c baz.c | |
7416 | $ d10v-elf-gcc -g -c grbx.c | |
7417 | $ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \ | |
7418 | baz.o grbx.o -Wl,-Td10v.ld -o overlays | |
474c8240 | 7419 | @end smallexample |
df0cd8c5 JB |
7420 | |
7421 | The build process is identical for any other architecture, except that | |
7422 | you must substitute the appropriate compiler and linker script for the | |
7423 | target system for @code{d10v-elf-gcc} and @code{d10v.ld}. | |
7424 | ||
7425 | ||
6d2ebf8b | 7426 | @node Languages |
c906108c SS |
7427 | @chapter Using @value{GDBN} with Different Languages |
7428 | @cindex languages | |
7429 | ||
c906108c SS |
7430 | Although programming languages generally have common aspects, they are |
7431 | rarely expressed in the same manner. For instance, in ANSI C, | |
7432 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in | |
7433 | Modula-2, it is accomplished by @code{p^}. Values can also be | |
5d161b24 | 7434 | represented (and displayed) differently. Hex numbers in C appear as |
c906108c | 7435 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. |
c906108c SS |
7436 | |
7437 | @cindex working language | |
7438 | Language-specific information is built into @value{GDBN} for some languages, | |
7439 | allowing you to express operations like the above in your program's | |
7440 | native language, and allowing @value{GDBN} to output values in a manner | |
7441 | consistent with the syntax of your program's native language. The | |
7442 | language you use to build expressions is called the @dfn{working | |
7443 | language}. | |
7444 | ||
7445 | @menu | |
7446 | * Setting:: Switching between source languages | |
7447 | * Show:: Displaying the language | |
c906108c | 7448 | * Checks:: Type and range checks |
c906108c SS |
7449 | * Support:: Supported languages |
7450 | @end menu | |
7451 | ||
6d2ebf8b | 7452 | @node Setting |
c906108c SS |
7453 | @section Switching between source languages |
7454 | ||
7455 | There are two ways to control the working language---either have @value{GDBN} | |
7456 | set it automatically, or select it manually yourself. You can use the | |
7457 | @code{set language} command for either purpose. On startup, @value{GDBN} | |
7458 | defaults to setting the language automatically. The working language is | |
7459 | used to determine how expressions you type are interpreted, how values | |
7460 | are printed, etc. | |
7461 | ||
7462 | In addition to the working language, every source file that | |
7463 | @value{GDBN} knows about has its own working language. For some object | |
7464 | file formats, the compiler might indicate which language a particular | |
7465 | source file is in. However, most of the time @value{GDBN} infers the | |
7466 | language from the name of the file. The language of a source file | |
b37052ae | 7467 | controls whether C@t{++} names are demangled---this way @code{backtrace} can |
c906108c | 7468 | show each frame appropriately for its own language. There is no way to |
d4f3574e SS |
7469 | set the language of a source file from within @value{GDBN}, but you can |
7470 | set the language associated with a filename extension. @xref{Show, , | |
7471 | Displaying the language}. | |
c906108c SS |
7472 | |
7473 | This is most commonly a problem when you use a program, such | |
5d161b24 | 7474 | as @code{cfront} or @code{f2c}, that generates C but is written in |
c906108c SS |
7475 | another language. In that case, make the |
7476 | program use @code{#line} directives in its C output; that way | |
7477 | @value{GDBN} will know the correct language of the source code of the original | |
7478 | program, and will display that source code, not the generated C code. | |
7479 | ||
7480 | @menu | |
7481 | * Filenames:: Filename extensions and languages. | |
7482 | * Manually:: Setting the working language manually | |
7483 | * Automatically:: Having @value{GDBN} infer the source language | |
7484 | @end menu | |
7485 | ||
6d2ebf8b | 7486 | @node Filenames |
c906108c SS |
7487 | @subsection List of filename extensions and languages |
7488 | ||
7489 | If a source file name ends in one of the following extensions, then | |
7490 | @value{GDBN} infers that its language is the one indicated. | |
7491 | ||
7492 | @table @file | |
7493 | ||
7494 | @item .c | |
7495 | C source file | |
7496 | ||
7497 | @item .C | |
7498 | @itemx .cc | |
7499 | @itemx .cp | |
7500 | @itemx .cpp | |
7501 | @itemx .cxx | |
7502 | @itemx .c++ | |
b37052ae | 7503 | C@t{++} source file |
c906108c SS |
7504 | |
7505 | @item .f | |
7506 | @itemx .F | |
7507 | Fortran source file | |
7508 | ||
c906108c SS |
7509 | @item .mod |
7510 | Modula-2 source file | |
c906108c SS |
7511 | |
7512 | @item .s | |
7513 | @itemx .S | |
7514 | Assembler source file. This actually behaves almost like C, but | |
7515 | @value{GDBN} does not skip over function prologues when stepping. | |
7516 | @end table | |
7517 | ||
7518 | In addition, you may set the language associated with a filename | |
7519 | extension. @xref{Show, , Displaying the language}. | |
7520 | ||
6d2ebf8b | 7521 | @node Manually |
c906108c SS |
7522 | @subsection Setting the working language |
7523 | ||
7524 | If you allow @value{GDBN} to set the language automatically, | |
7525 | expressions are interpreted the same way in your debugging session and | |
7526 | your program. | |
7527 | ||
7528 | @kindex set language | |
7529 | If you wish, you may set the language manually. To do this, issue the | |
7530 | command @samp{set language @var{lang}}, where @var{lang} is the name of | |
5d161b24 | 7531 | a language, such as |
c906108c | 7532 | @code{c} or @code{modula-2}. |
c906108c SS |
7533 | For a list of the supported languages, type @samp{set language}. |
7534 | ||
c906108c SS |
7535 | Setting the language manually prevents @value{GDBN} from updating the working |
7536 | language automatically. This can lead to confusion if you try | |
7537 | to debug a program when the working language is not the same as the | |
7538 | source language, when an expression is acceptable to both | |
7539 | languages---but means different things. For instance, if the current | |
7540 | source file were written in C, and @value{GDBN} was parsing Modula-2, a | |
7541 | command such as: | |
7542 | ||
474c8240 | 7543 | @smallexample |
c906108c | 7544 | print a = b + c |
474c8240 | 7545 | @end smallexample |
c906108c SS |
7546 | |
7547 | @noindent | |
7548 | might not have the effect you intended. In C, this means to add | |
7549 | @code{b} and @code{c} and place the result in @code{a}. The result | |
7550 | printed would be the value of @code{a}. In Modula-2, this means to compare | |
7551 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. | |
c906108c | 7552 | |
6d2ebf8b | 7553 | @node Automatically |
c906108c SS |
7554 | @subsection Having @value{GDBN} infer the source language |
7555 | ||
7556 | To have @value{GDBN} set the working language automatically, use | |
7557 | @samp{set language local} or @samp{set language auto}. @value{GDBN} | |
7558 | then infers the working language. That is, when your program stops in a | |
7559 | frame (usually by encountering a breakpoint), @value{GDBN} sets the | |
7560 | working language to the language recorded for the function in that | |
7561 | frame. If the language for a frame is unknown (that is, if the function | |
7562 | or block corresponding to the frame was defined in a source file that | |
7563 | does not have a recognized extension), the current working language is | |
7564 | not changed, and @value{GDBN} issues a warning. | |
7565 | ||
7566 | This may not seem necessary for most programs, which are written | |
7567 | entirely in one source language. However, program modules and libraries | |
7568 | written in one source language can be used by a main program written in | |
7569 | a different source language. Using @samp{set language auto} in this | |
7570 | case frees you from having to set the working language manually. | |
7571 | ||
6d2ebf8b | 7572 | @node Show |
c906108c | 7573 | @section Displaying the language |
c906108c SS |
7574 | |
7575 | The following commands help you find out which language is the | |
7576 | working language, and also what language source files were written in. | |
7577 | ||
7578 | @kindex show language | |
d4f3574e SS |
7579 | @kindex info frame@r{, show the source language} |
7580 | @kindex info source@r{, show the source language} | |
c906108c SS |
7581 | @table @code |
7582 | @item show language | |
7583 | Display the current working language. This is the | |
7584 | language you can use with commands such as @code{print} to | |
7585 | build and compute expressions that may involve variables in your program. | |
7586 | ||
7587 | @item info frame | |
5d161b24 | 7588 | Display the source language for this frame. This language becomes the |
c906108c | 7589 | working language if you use an identifier from this frame. |
5d161b24 | 7590 | @xref{Frame Info, ,Information about a frame}, to identify the other |
c906108c SS |
7591 | information listed here. |
7592 | ||
7593 | @item info source | |
7594 | Display the source language of this source file. | |
5d161b24 | 7595 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other |
c906108c SS |
7596 | information listed here. |
7597 | @end table | |
7598 | ||
7599 | In unusual circumstances, you may have source files with extensions | |
7600 | not in the standard list. You can then set the extension associated | |
7601 | with a language explicitly: | |
7602 | ||
7603 | @kindex set extension-language | |
7604 | @kindex info extensions | |
7605 | @table @code | |
7606 | @item set extension-language @var{.ext} @var{language} | |
7607 | Set source files with extension @var{.ext} to be assumed to be in | |
7608 | the source language @var{language}. | |
7609 | ||
7610 | @item info extensions | |
7611 | List all the filename extensions and the associated languages. | |
7612 | @end table | |
7613 | ||
6d2ebf8b | 7614 | @node Checks |
c906108c SS |
7615 | @section Type and range checking |
7616 | ||
7617 | @quotation | |
7618 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range | |
7619 | checking are included, but they do not yet have any effect. This | |
7620 | section documents the intended facilities. | |
7621 | @end quotation | |
7622 | @c FIXME remove warning when type/range code added | |
7623 | ||
7624 | Some languages are designed to guard you against making seemingly common | |
7625 | errors through a series of compile- and run-time checks. These include | |
7626 | checking the type of arguments to functions and operators, and making | |
7627 | sure mathematical overflows are caught at run time. Checks such as | |
7628 | these help to ensure a program's correctness once it has been compiled | |
7629 | by eliminating type mismatches, and providing active checks for range | |
7630 | errors when your program is running. | |
7631 | ||
7632 | @value{GDBN} can check for conditions like the above if you wish. | |
7633 | Although @value{GDBN} does not check the statements in your program, it | |
7634 | can check expressions entered directly into @value{GDBN} for evaluation via | |
7635 | the @code{print} command, for example. As with the working language, | |
7636 | @value{GDBN} can also decide whether or not to check automatically based on | |
7637 | your program's source language. @xref{Support, ,Supported languages}, | |
7638 | for the default settings of supported languages. | |
7639 | ||
7640 | @menu | |
7641 | * Type Checking:: An overview of type checking | |
7642 | * Range Checking:: An overview of range checking | |
7643 | @end menu | |
7644 | ||
7645 | @cindex type checking | |
7646 | @cindex checks, type | |
6d2ebf8b | 7647 | @node Type Checking |
c906108c SS |
7648 | @subsection An overview of type checking |
7649 | ||
7650 | Some languages, such as Modula-2, are strongly typed, meaning that the | |
7651 | arguments to operators and functions have to be of the correct type, | |
7652 | otherwise an error occurs. These checks prevent type mismatch | |
7653 | errors from ever causing any run-time problems. For example, | |
7654 | ||
7655 | @smallexample | |
7656 | 1 + 2 @result{} 3 | |
7657 | @exdent but | |
7658 | @error{} 1 + 2.3 | |
7659 | @end smallexample | |
7660 | ||
7661 | The second example fails because the @code{CARDINAL} 1 is not | |
7662 | type-compatible with the @code{REAL} 2.3. | |
7663 | ||
5d161b24 DB |
7664 | For the expressions you use in @value{GDBN} commands, you can tell the |
7665 | @value{GDBN} type checker to skip checking; | |
7666 | to treat any mismatches as errors and abandon the expression; | |
7667 | or to only issue warnings when type mismatches occur, | |
c906108c SS |
7668 | but evaluate the expression anyway. When you choose the last of |
7669 | these, @value{GDBN} evaluates expressions like the second example above, but | |
7670 | also issues a warning. | |
7671 | ||
5d161b24 DB |
7672 | Even if you turn type checking off, there may be other reasons |
7673 | related to type that prevent @value{GDBN} from evaluating an expression. | |
7674 | For instance, @value{GDBN} does not know how to add an @code{int} and | |
7675 | a @code{struct foo}. These particular type errors have nothing to do | |
7676 | with the language in use, and usually arise from expressions, such as | |
c906108c SS |
7677 | the one described above, which make little sense to evaluate anyway. |
7678 | ||
7679 | Each language defines to what degree it is strict about type. For | |
7680 | instance, both Modula-2 and C require the arguments to arithmetical | |
7681 | operators to be numbers. In C, enumerated types and pointers can be | |
7682 | represented as numbers, so that they are valid arguments to mathematical | |
7683 | operators. @xref{Support, ,Supported languages}, for further | |
7684 | details on specific languages. | |
7685 | ||
7686 | @value{GDBN} provides some additional commands for controlling the type checker: | |
7687 | ||
d4f3574e | 7688 | @kindex set check@r{, type} |
c906108c SS |
7689 | @kindex set check type |
7690 | @kindex show check type | |
7691 | @table @code | |
7692 | @item set check type auto | |
7693 | Set type checking on or off based on the current working language. | |
7694 | @xref{Support, ,Supported languages}, for the default settings for | |
7695 | each language. | |
7696 | ||
7697 | @item set check type on | |
7698 | @itemx set check type off | |
7699 | Set type checking on or off, overriding the default setting for the | |
7700 | current working language. Issue a warning if the setting does not | |
7701 | match the language default. If any type mismatches occur in | |
d4f3574e | 7702 | evaluating an expression while type checking is on, @value{GDBN} prints a |
c906108c SS |
7703 | message and aborts evaluation of the expression. |
7704 | ||
7705 | @item set check type warn | |
7706 | Cause the type checker to issue warnings, but to always attempt to | |
7707 | evaluate the expression. Evaluating the expression may still | |
7708 | be impossible for other reasons. For example, @value{GDBN} cannot add | |
7709 | numbers and structures. | |
7710 | ||
7711 | @item show type | |
5d161b24 | 7712 | Show the current setting of the type checker, and whether or not @value{GDBN} |
c906108c SS |
7713 | is setting it automatically. |
7714 | @end table | |
7715 | ||
7716 | @cindex range checking | |
7717 | @cindex checks, range | |
6d2ebf8b | 7718 | @node Range Checking |
c906108c SS |
7719 | @subsection An overview of range checking |
7720 | ||
7721 | In some languages (such as Modula-2), it is an error to exceed the | |
7722 | bounds of a type; this is enforced with run-time checks. Such range | |
7723 | checking is meant to ensure program correctness by making sure | |
7724 | computations do not overflow, or indices on an array element access do | |
7725 | not exceed the bounds of the array. | |
7726 | ||
7727 | For expressions you use in @value{GDBN} commands, you can tell | |
7728 | @value{GDBN} to treat range errors in one of three ways: ignore them, | |
7729 | always treat them as errors and abandon the expression, or issue | |
7730 | warnings but evaluate the expression anyway. | |
7731 | ||
7732 | A range error can result from numerical overflow, from exceeding an | |
7733 | array index bound, or when you type a constant that is not a member | |
7734 | of any type. Some languages, however, do not treat overflows as an | |
7735 | error. In many implementations of C, mathematical overflow causes the | |
7736 | result to ``wrap around'' to lower values---for example, if @var{m} is | |
7737 | the largest integer value, and @var{s} is the smallest, then | |
7738 | ||
474c8240 | 7739 | @smallexample |
c906108c | 7740 | @var{m} + 1 @result{} @var{s} |
474c8240 | 7741 | @end smallexample |
c906108c SS |
7742 | |
7743 | This, too, is specific to individual languages, and in some cases | |
7744 | specific to individual compilers or machines. @xref{Support, , | |
7745 | Supported languages}, for further details on specific languages. | |
7746 | ||
7747 | @value{GDBN} provides some additional commands for controlling the range checker: | |
7748 | ||
d4f3574e | 7749 | @kindex set check@r{, range} |
c906108c SS |
7750 | @kindex set check range |
7751 | @kindex show check range | |
7752 | @table @code | |
7753 | @item set check range auto | |
7754 | Set range checking on or off based on the current working language. | |
7755 | @xref{Support, ,Supported languages}, for the default settings for | |
7756 | each language. | |
7757 | ||
7758 | @item set check range on | |
7759 | @itemx set check range off | |
7760 | Set range checking on or off, overriding the default setting for the | |
7761 | current working language. A warning is issued if the setting does not | |
c3f6f71d JM |
7762 | match the language default. If a range error occurs and range checking is on, |
7763 | then a message is printed and evaluation of the expression is aborted. | |
c906108c SS |
7764 | |
7765 | @item set check range warn | |
7766 | Output messages when the @value{GDBN} range checker detects a range error, | |
7767 | but attempt to evaluate the expression anyway. Evaluating the | |
7768 | expression may still be impossible for other reasons, such as accessing | |
7769 | memory that the process does not own (a typical example from many Unix | |
7770 | systems). | |
7771 | ||
7772 | @item show range | |
7773 | Show the current setting of the range checker, and whether or not it is | |
7774 | being set automatically by @value{GDBN}. | |
7775 | @end table | |
c906108c | 7776 | |
6d2ebf8b | 7777 | @node Support |
c906108c | 7778 | @section Supported languages |
c906108c | 7779 | |
e632838e | 7780 | @value{GDBN} supports C, C@t{++}, Fortran, Java, assembly, and Modula-2. |
cce74817 | 7781 | @c This is false ... |
c906108c SS |
7782 | Some @value{GDBN} features may be used in expressions regardless of the |
7783 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, | |
7784 | and the @samp{@{type@}addr} construct (@pxref{Expressions, | |
7785 | ,Expressions}) can be used with the constructs of any supported | |
7786 | language. | |
7787 | ||
7788 | The following sections detail to what degree each source language is | |
7789 | supported by @value{GDBN}. These sections are not meant to be language | |
7790 | tutorials or references, but serve only as a reference guide to what the | |
7791 | @value{GDBN} expression parser accepts, and what input and output | |
7792 | formats should look like for different languages. There are many good | |
7793 | books written on each of these languages; please look to these for a | |
7794 | language reference or tutorial. | |
7795 | ||
c906108c | 7796 | @menu |
b37052ae | 7797 | * C:: C and C@t{++} |
cce74817 | 7798 | * Modula-2:: Modula-2 |
c906108c SS |
7799 | @end menu |
7800 | ||
6d2ebf8b | 7801 | @node C |
b37052ae | 7802 | @subsection C and C@t{++} |
7a292a7a | 7803 | |
b37052ae EZ |
7804 | @cindex C and C@t{++} |
7805 | @cindex expressions in C or C@t{++} | |
c906108c | 7806 | |
b37052ae | 7807 | Since C and C@t{++} are so closely related, many features of @value{GDBN} apply |
c906108c SS |
7808 | to both languages. Whenever this is the case, we discuss those languages |
7809 | together. | |
7810 | ||
41afff9a EZ |
7811 | @cindex C@t{++} |
7812 | @cindex @code{g++}, @sc{gnu} C@t{++} compiler | |
b37052ae EZ |
7813 | @cindex @sc{gnu} C@t{++} |
7814 | The C@t{++} debugging facilities are jointly implemented by the C@t{++} | |
7815 | compiler and @value{GDBN}. Therefore, to debug your C@t{++} code | |
7816 | effectively, you must compile your C@t{++} programs with a supported | |
7817 | C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++} | |
c906108c SS |
7818 | compiler (@code{aCC}). |
7819 | ||
0179ffac DC |
7820 | For best results when using @sc{gnu} C@t{++}, use the DWARF 2 debugging |
7821 | format; if it doesn't work on your system, try the stabs+ debugging | |
7822 | format. You can select those formats explicitly with the @code{g++} | |
7823 | command-line options @option{-gdwarf-2} and @option{-gstabs+}. | |
7824 | @xref{Debugging Options,,Options for Debugging Your Program or @sc{gnu} | |
7825 | CC, gcc.info, Using @sc{gnu} CC}. | |
c906108c | 7826 | |
c906108c | 7827 | @menu |
b37052ae EZ |
7828 | * C Operators:: C and C@t{++} operators |
7829 | * C Constants:: C and C@t{++} constants | |
7830 | * C plus plus expressions:: C@t{++} expressions | |
7831 | * C Defaults:: Default settings for C and C@t{++} | |
7832 | * C Checks:: C and C@t{++} type and range checks | |
c906108c | 7833 | * Debugging C:: @value{GDBN} and C |
b37052ae | 7834 | * Debugging C plus plus:: @value{GDBN} features for C@t{++} |
c906108c | 7835 | @end menu |
c906108c | 7836 | |
6d2ebf8b | 7837 | @node C Operators |
b37052ae | 7838 | @subsubsection C and C@t{++} operators |
7a292a7a | 7839 | |
b37052ae | 7840 | @cindex C and C@t{++} operators |
c906108c SS |
7841 | |
7842 | Operators must be defined on values of specific types. For instance, | |
7843 | @code{+} is defined on numbers, but not on structures. Operators are | |
5d161b24 | 7844 | often defined on groups of types. |
c906108c | 7845 | |
b37052ae | 7846 | For the purposes of C and C@t{++}, the following definitions hold: |
c906108c SS |
7847 | |
7848 | @itemize @bullet | |
53a5351d | 7849 | |
c906108c | 7850 | @item |
c906108c | 7851 | @emph{Integral types} include @code{int} with any of its storage-class |
b37052ae | 7852 | specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}. |
c906108c SS |
7853 | |
7854 | @item | |
d4f3574e SS |
7855 | @emph{Floating-point types} include @code{float}, @code{double}, and |
7856 | @code{long double} (if supported by the target platform). | |
c906108c SS |
7857 | |
7858 | @item | |
53a5351d | 7859 | @emph{Pointer types} include all types defined as @code{(@var{type} *)}. |
c906108c SS |
7860 | |
7861 | @item | |
7862 | @emph{Scalar types} include all of the above. | |
53a5351d | 7863 | |
c906108c SS |
7864 | @end itemize |
7865 | ||
7866 | @noindent | |
7867 | The following operators are supported. They are listed here | |
7868 | in order of increasing precedence: | |
7869 | ||
7870 | @table @code | |
7871 | @item , | |
7872 | The comma or sequencing operator. Expressions in a comma-separated list | |
7873 | are evaluated from left to right, with the result of the entire | |
7874 | expression being the last expression evaluated. | |
7875 | ||
7876 | @item = | |
7877 | Assignment. The value of an assignment expression is the value | |
7878 | assigned. Defined on scalar types. | |
7879 | ||
7880 | @item @var{op}= | |
7881 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, | |
7882 | and translated to @w{@code{@var{a} = @var{a op b}}}. | |
d4f3574e | 7883 | @w{@code{@var{op}=}} and @code{=} have the same precedence. |
c906108c SS |
7884 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, |
7885 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. | |
7886 | ||
7887 | @item ?: | |
7888 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought | |
7889 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an | |
7890 | integral type. | |
7891 | ||
7892 | @item || | |
7893 | Logical @sc{or}. Defined on integral types. | |
7894 | ||
7895 | @item && | |
7896 | Logical @sc{and}. Defined on integral types. | |
7897 | ||
7898 | @item | | |
7899 | Bitwise @sc{or}. Defined on integral types. | |
7900 | ||
7901 | @item ^ | |
7902 | Bitwise exclusive-@sc{or}. Defined on integral types. | |
7903 | ||
7904 | @item & | |
7905 | Bitwise @sc{and}. Defined on integral types. | |
7906 | ||
7907 | @item ==@r{, }!= | |
7908 | Equality and inequality. Defined on scalar types. The value of these | |
7909 | expressions is 0 for false and non-zero for true. | |
7910 | ||
7911 | @item <@r{, }>@r{, }<=@r{, }>= | |
7912 | Less than, greater than, less than or equal, greater than or equal. | |
7913 | Defined on scalar types. The value of these expressions is 0 for false | |
7914 | and non-zero for true. | |
7915 | ||
7916 | @item <<@r{, }>> | |
7917 | left shift, and right shift. Defined on integral types. | |
7918 | ||
7919 | @item @@ | |
7920 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
7921 | ||
7922 | @item +@r{, }- | |
7923 | Addition and subtraction. Defined on integral types, floating-point types and | |
7924 | pointer types. | |
7925 | ||
7926 | @item *@r{, }/@r{, }% | |
7927 | Multiplication, division, and modulus. Multiplication and division are | |
7928 | defined on integral and floating-point types. Modulus is defined on | |
7929 | integral types. | |
7930 | ||
7931 | @item ++@r{, }-- | |
7932 | Increment and decrement. When appearing before a variable, the | |
7933 | operation is performed before the variable is used in an expression; | |
7934 | when appearing after it, the variable's value is used before the | |
7935 | operation takes place. | |
7936 | ||
7937 | @item * | |
7938 | Pointer dereferencing. Defined on pointer types. Same precedence as | |
7939 | @code{++}. | |
7940 | ||
7941 | @item & | |
7942 | Address operator. Defined on variables. Same precedence as @code{++}. | |
7943 | ||
b37052ae EZ |
7944 | For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is |
7945 | allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})} | |
c906108c | 7946 | (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address |
b37052ae | 7947 | where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is |
c906108c | 7948 | stored. |
c906108c SS |
7949 | |
7950 | @item - | |
7951 | Negative. Defined on integral and floating-point types. Same | |
7952 | precedence as @code{++}. | |
7953 | ||
7954 | @item ! | |
7955 | Logical negation. Defined on integral types. Same precedence as | |
7956 | @code{++}. | |
7957 | ||
7958 | @item ~ | |
7959 | Bitwise complement operator. Defined on integral types. Same precedence as | |
7960 | @code{++}. | |
7961 | ||
7962 | ||
7963 | @item .@r{, }-> | |
7964 | Structure member, and pointer-to-structure member. For convenience, | |
7965 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a | |
7966 | pointer based on the stored type information. | |
7967 | Defined on @code{struct} and @code{union} data. | |
7968 | ||
c906108c SS |
7969 | @item .*@r{, }->* |
7970 | Dereferences of pointers to members. | |
c906108c SS |
7971 | |
7972 | @item [] | |
7973 | Array indexing. @code{@var{a}[@var{i}]} is defined as | |
7974 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. | |
7975 | ||
7976 | @item () | |
7977 | Function parameter list. Same precedence as @code{->}. | |
7978 | ||
c906108c | 7979 | @item :: |
b37052ae | 7980 | C@t{++} scope resolution operator. Defined on @code{struct}, @code{union}, |
7a292a7a | 7981 | and @code{class} types. |
c906108c SS |
7982 | |
7983 | @item :: | |
7a292a7a SS |
7984 | Doubled colons also represent the @value{GDBN} scope operator |
7985 | (@pxref{Expressions, ,Expressions}). Same precedence as @code{::}, | |
7986 | above. | |
c906108c SS |
7987 | @end table |
7988 | ||
c906108c SS |
7989 | If an operator is redefined in the user code, @value{GDBN} usually |
7990 | attempts to invoke the redefined version instead of using the operator's | |
7991 | predefined meaning. | |
c906108c | 7992 | |
c906108c | 7993 | @menu |
5d161b24 | 7994 | * C Constants:: |
c906108c SS |
7995 | @end menu |
7996 | ||
6d2ebf8b | 7997 | @node C Constants |
b37052ae | 7998 | @subsubsection C and C@t{++} constants |
c906108c | 7999 | |
b37052ae | 8000 | @cindex C and C@t{++} constants |
c906108c | 8001 | |
b37052ae | 8002 | @value{GDBN} allows you to express the constants of C and C@t{++} in the |
c906108c | 8003 | following ways: |
c906108c SS |
8004 | |
8005 | @itemize @bullet | |
8006 | @item | |
8007 | Integer constants are a sequence of digits. Octal constants are | |
6ca652b0 EZ |
8008 | specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants |
8009 | by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter | |
c906108c SS |
8010 | @samp{l}, specifying that the constant should be treated as a |
8011 | @code{long} value. | |
8012 | ||
8013 | @item | |
8014 | Floating point constants are a sequence of digits, followed by a decimal | |
8015 | point, followed by a sequence of digits, and optionally followed by an | |
8016 | exponent. An exponent is of the form: | |
8017 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another | |
8018 | sequence of digits. The @samp{+} is optional for positive exponents. | |
d4f3574e SS |
8019 | A floating-point constant may also end with a letter @samp{f} or |
8020 | @samp{F}, specifying that the constant should be treated as being of | |
8021 | the @code{float} (as opposed to the default @code{double}) type; or with | |
8022 | a letter @samp{l} or @samp{L}, which specifies a @code{long double} | |
8023 | constant. | |
c906108c SS |
8024 | |
8025 | @item | |
8026 | Enumerated constants consist of enumerated identifiers, or their | |
8027 | integral equivalents. | |
8028 | ||
8029 | @item | |
8030 | Character constants are a single character surrounded by single quotes | |
8031 | (@code{'}), or a number---the ordinal value of the corresponding character | |
d4f3574e | 8032 | (usually its @sc{ascii} value). Within quotes, the single character may |
c906108c SS |
8033 | be represented by a letter or by @dfn{escape sequences}, which are of |
8034 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation | |
8035 | of the character's ordinal value; or of the form @samp{\@var{x}}, where | |
8036 | @samp{@var{x}} is a predefined special character---for example, | |
8037 | @samp{\n} for newline. | |
8038 | ||
8039 | @item | |
96a2c332 SS |
8040 | String constants are a sequence of character constants surrounded by |
8041 | double quotes (@code{"}). Any valid character constant (as described | |
8042 | above) may appear. Double quotes within the string must be preceded by | |
8043 | a backslash, so for instance @samp{"a\"b'c"} is a string of five | |
8044 | characters. | |
c906108c SS |
8045 | |
8046 | @item | |
8047 | Pointer constants are an integral value. You can also write pointers | |
8048 | to constants using the C operator @samp{&}. | |
8049 | ||
8050 | @item | |
8051 | Array constants are comma-separated lists surrounded by braces @samp{@{} | |
8052 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of | |
8053 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, | |
8054 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. | |
8055 | @end itemize | |
8056 | ||
c906108c | 8057 | @menu |
5d161b24 DB |
8058 | * C plus plus expressions:: |
8059 | * C Defaults:: | |
8060 | * C Checks:: | |
c906108c | 8061 | |
5d161b24 | 8062 | * Debugging C:: |
c906108c SS |
8063 | @end menu |
8064 | ||
6d2ebf8b | 8065 | @node C plus plus expressions |
b37052ae EZ |
8066 | @subsubsection C@t{++} expressions |
8067 | ||
8068 | @cindex expressions in C@t{++} | |
8069 | @value{GDBN} expression handling can interpret most C@t{++} expressions. | |
8070 | ||
0179ffac DC |
8071 | @cindex debugging C@t{++} programs |
8072 | @cindex C@t{++} compilers | |
8073 | @cindex debug formats and C@t{++} | |
8074 | @cindex @value{NGCC} and C@t{++} | |
c906108c | 8075 | @quotation |
b37052ae | 8076 | @emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use the |
0179ffac DC |
8077 | proper compiler and the proper debug format. Currently, @value{GDBN} |
8078 | works best when debugging C@t{++} code that is compiled with | |
8079 | @value{NGCC} 2.95.3 or with @value{NGCC} 3.1 or newer, using the options | |
8080 | @option{-gdwarf-2} or @option{-gstabs+}. DWARF 2 is preferred over | |
8081 | stabs+. Most configurations of @value{NGCC} emit either DWARF 2 or | |
8082 | stabs+ as their default debug format, so you usually don't need to | |
8083 | specify a debug format explicitly. Other compilers and/or debug formats | |
8084 | are likely to work badly or not at all when using @value{GDBN} to debug | |
8085 | C@t{++} code. | |
c906108c | 8086 | @end quotation |
c906108c SS |
8087 | |
8088 | @enumerate | |
8089 | ||
8090 | @cindex member functions | |
8091 | @item | |
8092 | Member function calls are allowed; you can use expressions like | |
8093 | ||
474c8240 | 8094 | @smallexample |
c906108c | 8095 | count = aml->GetOriginal(x, y) |
474c8240 | 8096 | @end smallexample |
c906108c | 8097 | |
41afff9a | 8098 | @vindex this@r{, inside C@t{++} member functions} |
b37052ae | 8099 | @cindex namespace in C@t{++} |
c906108c SS |
8100 | @item |
8101 | While a member function is active (in the selected stack frame), your | |
8102 | expressions have the same namespace available as the member function; | |
8103 | that is, @value{GDBN} allows implicit references to the class instance | |
b37052ae | 8104 | pointer @code{this} following the same rules as C@t{++}. |
c906108c | 8105 | |
c906108c | 8106 | @cindex call overloaded functions |
d4f3574e | 8107 | @cindex overloaded functions, calling |
b37052ae | 8108 | @cindex type conversions in C@t{++} |
c906108c SS |
8109 | @item |
8110 | You can call overloaded functions; @value{GDBN} resolves the function | |
d4f3574e | 8111 | call to the right definition, with some restrictions. @value{GDBN} does not |
c906108c SS |
8112 | perform overload resolution involving user-defined type conversions, |
8113 | calls to constructors, or instantiations of templates that do not exist | |
8114 | in the program. It also cannot handle ellipsis argument lists or | |
8115 | default arguments. | |
8116 | ||
8117 | It does perform integral conversions and promotions, floating-point | |
8118 | promotions, arithmetic conversions, pointer conversions, conversions of | |
8119 | class objects to base classes, and standard conversions such as those of | |
8120 | functions or arrays to pointers; it requires an exact match on the | |
8121 | number of function arguments. | |
8122 | ||
8123 | Overload resolution is always performed, unless you have specified | |
8124 | @code{set overload-resolution off}. @xref{Debugging C plus plus, | |
b37052ae | 8125 | ,@value{GDBN} features for C@t{++}}. |
c906108c | 8126 | |
d4f3574e | 8127 | You must specify @code{set overload-resolution off} in order to use an |
c906108c SS |
8128 | explicit function signature to call an overloaded function, as in |
8129 | @smallexample | |
8130 | p 'foo(char,int)'('x', 13) | |
8131 | @end smallexample | |
d4f3574e | 8132 | |
c906108c | 8133 | The @value{GDBN} command-completion facility can simplify this; |
d4f3574e | 8134 | see @ref{Completion, ,Command completion}. |
c906108c | 8135 | |
c906108c SS |
8136 | @cindex reference declarations |
8137 | @item | |
b37052ae EZ |
8138 | @value{GDBN} understands variables declared as C@t{++} references; you can use |
8139 | them in expressions just as you do in C@t{++} source---they are automatically | |
c906108c SS |
8140 | dereferenced. |
8141 | ||
8142 | In the parameter list shown when @value{GDBN} displays a frame, the values of | |
8143 | reference variables are not displayed (unlike other variables); this | |
8144 | avoids clutter, since references are often used for large structures. | |
8145 | The @emph{address} of a reference variable is always shown, unless | |
8146 | you have specified @samp{set print address off}. | |
8147 | ||
8148 | @item | |
b37052ae | 8149 | @value{GDBN} supports the C@t{++} name resolution operator @code{::}---your |
c906108c SS |
8150 | expressions can use it just as expressions in your program do. Since |
8151 | one scope may be defined in another, you can use @code{::} repeatedly if | |
8152 | necessary, for example in an expression like | |
8153 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows | |
b37052ae | 8154 | resolving name scope by reference to source files, in both C and C@t{++} |
c906108c SS |
8155 | debugging (@pxref{Variables, ,Program variables}). |
8156 | @end enumerate | |
8157 | ||
b37052ae | 8158 | In addition, when used with HP's C@t{++} compiler, @value{GDBN} supports |
53a5351d JM |
8159 | calling virtual functions correctly, printing out virtual bases of |
8160 | objects, calling functions in a base subobject, casting objects, and | |
8161 | invoking user-defined operators. | |
c906108c | 8162 | |
6d2ebf8b | 8163 | @node C Defaults |
b37052ae | 8164 | @subsubsection C and C@t{++} defaults |
7a292a7a | 8165 | |
b37052ae | 8166 | @cindex C and C@t{++} defaults |
c906108c | 8167 | |
c906108c SS |
8168 | If you allow @value{GDBN} to set type and range checking automatically, they |
8169 | both default to @code{off} whenever the working language changes to | |
b37052ae | 8170 | C or C@t{++}. This happens regardless of whether you or @value{GDBN} |
c906108c | 8171 | selects the working language. |
c906108c SS |
8172 | |
8173 | If you allow @value{GDBN} to set the language automatically, it | |
8174 | recognizes source files whose names end with @file{.c}, @file{.C}, or | |
8175 | @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of | |
b37052ae | 8176 | these files, it sets the working language to C or C@t{++}. |
c906108c SS |
8177 | @xref{Automatically, ,Having @value{GDBN} infer the source language}, |
8178 | for further details. | |
8179 | ||
c906108c SS |
8180 | @c Type checking is (a) primarily motivated by Modula-2, and (b) |
8181 | @c unimplemented. If (b) changes, it might make sense to let this node | |
8182 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. | |
7a292a7a | 8183 | |
6d2ebf8b | 8184 | @node C Checks |
b37052ae | 8185 | @subsubsection C and C@t{++} type and range checks |
7a292a7a | 8186 | |
b37052ae | 8187 | @cindex C and C@t{++} checks |
c906108c | 8188 | |
b37052ae | 8189 | By default, when @value{GDBN} parses C or C@t{++} expressions, type checking |
c906108c SS |
8190 | is not used. However, if you turn type checking on, @value{GDBN} |
8191 | considers two variables type equivalent if: | |
8192 | ||
8193 | @itemize @bullet | |
8194 | @item | |
8195 | The two variables are structured and have the same structure, union, or | |
8196 | enumerated tag. | |
8197 | ||
8198 | @item | |
8199 | The two variables have the same type name, or types that have been | |
8200 | declared equivalent through @code{typedef}. | |
8201 | ||
8202 | @ignore | |
8203 | @c leaving this out because neither J Gilmore nor R Pesch understand it. | |
8204 | @c FIXME--beers? | |
8205 | @item | |
8206 | The two @code{struct}, @code{union}, or @code{enum} variables are | |
8207 | declared in the same declaration. (Note: this may not be true for all C | |
8208 | compilers.) | |
8209 | @end ignore | |
8210 | @end itemize | |
8211 | ||
8212 | Range checking, if turned on, is done on mathematical operations. Array | |
8213 | indices are not checked, since they are often used to index a pointer | |
8214 | that is not itself an array. | |
c906108c | 8215 | |
6d2ebf8b | 8216 | @node Debugging C |
c906108c | 8217 | @subsubsection @value{GDBN} and C |
c906108c SS |
8218 | |
8219 | The @code{set print union} and @code{show print union} commands apply to | |
8220 | the @code{union} type. When set to @samp{on}, any @code{union} that is | |
7a292a7a SS |
8221 | inside a @code{struct} or @code{class} is also printed. Otherwise, it |
8222 | appears as @samp{@{...@}}. | |
c906108c SS |
8223 | |
8224 | The @code{@@} operator aids in the debugging of dynamic arrays, formed | |
8225 | with pointers and a memory allocation function. @xref{Expressions, | |
8226 | ,Expressions}. | |
8227 | ||
c906108c | 8228 | @menu |
5d161b24 | 8229 | * Debugging C plus plus:: |
c906108c SS |
8230 | @end menu |
8231 | ||
6d2ebf8b | 8232 | @node Debugging C plus plus |
b37052ae | 8233 | @subsubsection @value{GDBN} features for C@t{++} |
c906108c | 8234 | |
b37052ae | 8235 | @cindex commands for C@t{++} |
7a292a7a | 8236 | |
b37052ae EZ |
8237 | Some @value{GDBN} commands are particularly useful with C@t{++}, and some are |
8238 | designed specifically for use with C@t{++}. Here is a summary: | |
c906108c SS |
8239 | |
8240 | @table @code | |
8241 | @cindex break in overloaded functions | |
8242 | @item @r{breakpoint menus} | |
8243 | When you want a breakpoint in a function whose name is overloaded, | |
8244 | @value{GDBN} breakpoint menus help you specify which function definition | |
8245 | you want. @xref{Breakpoint Menus,,Breakpoint menus}. | |
8246 | ||
b37052ae | 8247 | @cindex overloading in C@t{++} |
c906108c SS |
8248 | @item rbreak @var{regex} |
8249 | Setting breakpoints using regular expressions is helpful for setting | |
8250 | breakpoints on overloaded functions that are not members of any special | |
8251 | classes. | |
8252 | @xref{Set Breaks, ,Setting breakpoints}. | |
8253 | ||
b37052ae | 8254 | @cindex C@t{++} exception handling |
c906108c SS |
8255 | @item catch throw |
8256 | @itemx catch catch | |
b37052ae | 8257 | Debug C@t{++} exception handling using these commands. @xref{Set |
c906108c SS |
8258 | Catchpoints, , Setting catchpoints}. |
8259 | ||
8260 | @cindex inheritance | |
8261 | @item ptype @var{typename} | |
8262 | Print inheritance relationships as well as other information for type | |
8263 | @var{typename}. | |
8264 | @xref{Symbols, ,Examining the Symbol Table}. | |
8265 | ||
b37052ae | 8266 | @cindex C@t{++} symbol display |
c906108c SS |
8267 | @item set print demangle |
8268 | @itemx show print demangle | |
8269 | @itemx set print asm-demangle | |
8270 | @itemx show print asm-demangle | |
b37052ae EZ |
8271 | Control whether C@t{++} symbols display in their source form, both when |
8272 | displaying code as C@t{++} source and when displaying disassemblies. | |
c906108c SS |
8273 | @xref{Print Settings, ,Print settings}. |
8274 | ||
8275 | @item set print object | |
8276 | @itemx show print object | |
8277 | Choose whether to print derived (actual) or declared types of objects. | |
8278 | @xref{Print Settings, ,Print settings}. | |
8279 | ||
8280 | @item set print vtbl | |
8281 | @itemx show print vtbl | |
8282 | Control the format for printing virtual function tables. | |
8283 | @xref{Print Settings, ,Print settings}. | |
c906108c | 8284 | (The @code{vtbl} commands do not work on programs compiled with the HP |
b37052ae | 8285 | ANSI C@t{++} compiler (@code{aCC}).) |
c906108c SS |
8286 | |
8287 | @kindex set overload-resolution | |
d4f3574e | 8288 | @cindex overloaded functions, overload resolution |
c906108c | 8289 | @item set overload-resolution on |
b37052ae | 8290 | Enable overload resolution for C@t{++} expression evaluation. The default |
c906108c SS |
8291 | is on. For overloaded functions, @value{GDBN} evaluates the arguments |
8292 | and searches for a function whose signature matches the argument types, | |
b37052ae | 8293 | using the standard C@t{++} conversion rules (see @ref{C plus plus expressions, ,C@t{++} |
d4f3574e | 8294 | expressions}, for details). If it cannot find a match, it emits a |
c906108c SS |
8295 | message. |
8296 | ||
8297 | @item set overload-resolution off | |
b37052ae | 8298 | Disable overload resolution for C@t{++} expression evaluation. For |
c906108c SS |
8299 | overloaded functions that are not class member functions, @value{GDBN} |
8300 | chooses the first function of the specified name that it finds in the | |
8301 | symbol table, whether or not its arguments are of the correct type. For | |
8302 | overloaded functions that are class member functions, @value{GDBN} | |
8303 | searches for a function whose signature @emph{exactly} matches the | |
8304 | argument types. | |
c906108c SS |
8305 | |
8306 | @item @r{Overloaded symbol names} | |
8307 | You can specify a particular definition of an overloaded symbol, using | |
b37052ae | 8308 | the same notation that is used to declare such symbols in C@t{++}: type |
c906108c SS |
8309 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can |
8310 | also use the @value{GDBN} command-line word completion facilities to list the | |
8311 | available choices, or to finish the type list for you. | |
8312 | @xref{Completion,, Command completion}, for details on how to do this. | |
8313 | @end table | |
c906108c | 8314 | |
6d2ebf8b | 8315 | @node Modula-2 |
c906108c | 8316 | @subsection Modula-2 |
7a292a7a | 8317 | |
d4f3574e | 8318 | @cindex Modula-2, @value{GDBN} support |
c906108c SS |
8319 | |
8320 | The extensions made to @value{GDBN} to support Modula-2 only support | |
8321 | output from the @sc{gnu} Modula-2 compiler (which is currently being | |
8322 | developed). Other Modula-2 compilers are not currently supported, and | |
8323 | attempting to debug executables produced by them is most likely | |
8324 | to give an error as @value{GDBN} reads in the executable's symbol | |
8325 | table. | |
8326 | ||
8327 | @cindex expressions in Modula-2 | |
8328 | @menu | |
8329 | * M2 Operators:: Built-in operators | |
8330 | * Built-In Func/Proc:: Built-in functions and procedures | |
8331 | * M2 Constants:: Modula-2 constants | |
8332 | * M2 Defaults:: Default settings for Modula-2 | |
8333 | * Deviations:: Deviations from standard Modula-2 | |
8334 | * M2 Checks:: Modula-2 type and range checks | |
8335 | * M2 Scope:: The scope operators @code{::} and @code{.} | |
8336 | * GDB/M2:: @value{GDBN} and Modula-2 | |
8337 | @end menu | |
8338 | ||
6d2ebf8b | 8339 | @node M2 Operators |
c906108c SS |
8340 | @subsubsection Operators |
8341 | @cindex Modula-2 operators | |
8342 | ||
8343 | Operators must be defined on values of specific types. For instance, | |
8344 | @code{+} is defined on numbers, but not on structures. Operators are | |
8345 | often defined on groups of types. For the purposes of Modula-2, the | |
8346 | following definitions hold: | |
8347 | ||
8348 | @itemize @bullet | |
8349 | ||
8350 | @item | |
8351 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and | |
8352 | their subranges. | |
8353 | ||
8354 | @item | |
8355 | @emph{Character types} consist of @code{CHAR} and its subranges. | |
8356 | ||
8357 | @item | |
8358 | @emph{Floating-point types} consist of @code{REAL}. | |
8359 | ||
8360 | @item | |
8361 | @emph{Pointer types} consist of anything declared as @code{POINTER TO | |
8362 | @var{type}}. | |
8363 | ||
8364 | @item | |
8365 | @emph{Scalar types} consist of all of the above. | |
8366 | ||
8367 | @item | |
8368 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. | |
8369 | ||
8370 | @item | |
8371 | @emph{Boolean types} consist of @code{BOOLEAN}. | |
8372 | @end itemize | |
8373 | ||
8374 | @noindent | |
8375 | The following operators are supported, and appear in order of | |
8376 | increasing precedence: | |
8377 | ||
8378 | @table @code | |
8379 | @item , | |
8380 | Function argument or array index separator. | |
8381 | ||
8382 | @item := | |
8383 | Assignment. The value of @var{var} @code{:=} @var{value} is | |
8384 | @var{value}. | |
8385 | ||
8386 | @item <@r{, }> | |
8387 | Less than, greater than on integral, floating-point, or enumerated | |
8388 | types. | |
8389 | ||
8390 | @item <=@r{, }>= | |
96a2c332 | 8391 | Less than or equal to, greater than or equal to |
c906108c SS |
8392 | on integral, floating-point and enumerated types, or set inclusion on |
8393 | set types. Same precedence as @code{<}. | |
8394 | ||
8395 | @item =@r{, }<>@r{, }# | |
8396 | Equality and two ways of expressing inequality, valid on scalar types. | |
8397 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is | |
8398 | available for inequality, since @code{#} conflicts with the script | |
8399 | comment character. | |
8400 | ||
8401 | @item IN | |
8402 | Set membership. Defined on set types and the types of their members. | |
8403 | Same precedence as @code{<}. | |
8404 | ||
8405 | @item OR | |
8406 | Boolean disjunction. Defined on boolean types. | |
8407 | ||
8408 | @item AND@r{, }& | |
d4f3574e | 8409 | Boolean conjunction. Defined on boolean types. |
c906108c SS |
8410 | |
8411 | @item @@ | |
8412 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
8413 | ||
8414 | @item +@r{, }- | |
8415 | Addition and subtraction on integral and floating-point types, or union | |
8416 | and difference on set types. | |
8417 | ||
8418 | @item * | |
8419 | Multiplication on integral and floating-point types, or set intersection | |
8420 | on set types. | |
8421 | ||
8422 | @item / | |
8423 | Division on floating-point types, or symmetric set difference on set | |
8424 | types. Same precedence as @code{*}. | |
8425 | ||
8426 | @item DIV@r{, }MOD | |
8427 | Integer division and remainder. Defined on integral types. Same | |
8428 | precedence as @code{*}. | |
8429 | ||
8430 | @item - | |
8431 | Negative. Defined on @code{INTEGER} and @code{REAL} data. | |
8432 | ||
8433 | @item ^ | |
8434 | Pointer dereferencing. Defined on pointer types. | |
8435 | ||
8436 | @item NOT | |
8437 | Boolean negation. Defined on boolean types. Same precedence as | |
8438 | @code{^}. | |
8439 | ||
8440 | @item . | |
8441 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same | |
8442 | precedence as @code{^}. | |
8443 | ||
8444 | @item [] | |
8445 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. | |
8446 | ||
8447 | @item () | |
8448 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence | |
8449 | as @code{^}. | |
8450 | ||
8451 | @item ::@r{, }. | |
8452 | @value{GDBN} and Modula-2 scope operators. | |
8453 | @end table | |
8454 | ||
8455 | @quotation | |
8456 | @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} | |
8457 | treats the use of the operator @code{IN}, or the use of operators | |
8458 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, | |
8459 | @code{<=}, and @code{>=} on sets as an error. | |
8460 | @end quotation | |
8461 | ||
cb51c4e0 | 8462 | |
6d2ebf8b | 8463 | @node Built-In Func/Proc |
c906108c | 8464 | @subsubsection Built-in functions and procedures |
cb51c4e0 | 8465 | @cindex Modula-2 built-ins |
c906108c SS |
8466 | |
8467 | Modula-2 also makes available several built-in procedures and functions. | |
8468 | In describing these, the following metavariables are used: | |
8469 | ||
8470 | @table @var | |
8471 | ||
8472 | @item a | |
8473 | represents an @code{ARRAY} variable. | |
8474 | ||
8475 | @item c | |
8476 | represents a @code{CHAR} constant or variable. | |
8477 | ||
8478 | @item i | |
8479 | represents a variable or constant of integral type. | |
8480 | ||
8481 | @item m | |
8482 | represents an identifier that belongs to a set. Generally used in the | |
8483 | same function with the metavariable @var{s}. The type of @var{s} should | |
8484 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). | |
8485 | ||
8486 | @item n | |
8487 | represents a variable or constant of integral or floating-point type. | |
8488 | ||
8489 | @item r | |
8490 | represents a variable or constant of floating-point type. | |
8491 | ||
8492 | @item t | |
8493 | represents a type. | |
8494 | ||
8495 | @item v | |
8496 | represents a variable. | |
8497 | ||
8498 | @item x | |
8499 | represents a variable or constant of one of many types. See the | |
8500 | explanation of the function for details. | |
8501 | @end table | |
8502 | ||
8503 | All Modula-2 built-in procedures also return a result, described below. | |
8504 | ||
8505 | @table @code | |
8506 | @item ABS(@var{n}) | |
8507 | Returns the absolute value of @var{n}. | |
8508 | ||
8509 | @item CAP(@var{c}) | |
8510 | If @var{c} is a lower case letter, it returns its upper case | |
c3f6f71d | 8511 | equivalent, otherwise it returns its argument. |
c906108c SS |
8512 | |
8513 | @item CHR(@var{i}) | |
8514 | Returns the character whose ordinal value is @var{i}. | |
8515 | ||
8516 | @item DEC(@var{v}) | |
c3f6f71d | 8517 | Decrements the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
8518 | |
8519 | @item DEC(@var{v},@var{i}) | |
8520 | Decrements the value in the variable @var{v} by @var{i}. Returns the | |
8521 | new value. | |
8522 | ||
8523 | @item EXCL(@var{m},@var{s}) | |
8524 | Removes the element @var{m} from the set @var{s}. Returns the new | |
8525 | set. | |
8526 | ||
8527 | @item FLOAT(@var{i}) | |
8528 | Returns the floating point equivalent of the integer @var{i}. | |
8529 | ||
8530 | @item HIGH(@var{a}) | |
8531 | Returns the index of the last member of @var{a}. | |
8532 | ||
8533 | @item INC(@var{v}) | |
c3f6f71d | 8534 | Increments the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
8535 | |
8536 | @item INC(@var{v},@var{i}) | |
8537 | Increments the value in the variable @var{v} by @var{i}. Returns the | |
8538 | new value. | |
8539 | ||
8540 | @item INCL(@var{m},@var{s}) | |
8541 | Adds the element @var{m} to the set @var{s} if it is not already | |
8542 | there. Returns the new set. | |
8543 | ||
8544 | @item MAX(@var{t}) | |
8545 | Returns the maximum value of the type @var{t}. | |
8546 | ||
8547 | @item MIN(@var{t}) | |
8548 | Returns the minimum value of the type @var{t}. | |
8549 | ||
8550 | @item ODD(@var{i}) | |
8551 | Returns boolean TRUE if @var{i} is an odd number. | |
8552 | ||
8553 | @item ORD(@var{x}) | |
8554 | Returns the ordinal value of its argument. For example, the ordinal | |
c3f6f71d JM |
8555 | value of a character is its @sc{ascii} value (on machines supporting the |
8556 | @sc{ascii} character set). @var{x} must be of an ordered type, which include | |
c906108c SS |
8557 | integral, character and enumerated types. |
8558 | ||
8559 | @item SIZE(@var{x}) | |
8560 | Returns the size of its argument. @var{x} can be a variable or a type. | |
8561 | ||
8562 | @item TRUNC(@var{r}) | |
8563 | Returns the integral part of @var{r}. | |
8564 | ||
8565 | @item VAL(@var{t},@var{i}) | |
8566 | Returns the member of the type @var{t} whose ordinal value is @var{i}. | |
8567 | @end table | |
8568 | ||
8569 | @quotation | |
8570 | @emph{Warning:} Sets and their operations are not yet supported, so | |
8571 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as | |
8572 | an error. | |
8573 | @end quotation | |
8574 | ||
8575 | @cindex Modula-2 constants | |
6d2ebf8b | 8576 | @node M2 Constants |
c906108c SS |
8577 | @subsubsection Constants |
8578 | ||
8579 | @value{GDBN} allows you to express the constants of Modula-2 in the following | |
8580 | ways: | |
8581 | ||
8582 | @itemize @bullet | |
8583 | ||
8584 | @item | |
8585 | Integer constants are simply a sequence of digits. When used in an | |
8586 | expression, a constant is interpreted to be type-compatible with the | |
8587 | rest of the expression. Hexadecimal integers are specified by a | |
8588 | trailing @samp{H}, and octal integers by a trailing @samp{B}. | |
8589 | ||
8590 | @item | |
8591 | Floating point constants appear as a sequence of digits, followed by a | |
8592 | decimal point and another sequence of digits. An optional exponent can | |
8593 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where | |
8594 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the | |
8595 | digits of the floating point constant must be valid decimal (base 10) | |
8596 | digits. | |
8597 | ||
8598 | @item | |
8599 | Character constants consist of a single character enclosed by a pair of | |
8600 | like quotes, either single (@code{'}) or double (@code{"}). They may | |
c3f6f71d | 8601 | also be expressed by their ordinal value (their @sc{ascii} value, usually) |
c906108c SS |
8602 | followed by a @samp{C}. |
8603 | ||
8604 | @item | |
8605 | String constants consist of a sequence of characters enclosed by a | |
8606 | pair of like quotes, either single (@code{'}) or double (@code{"}). | |
8607 | Escape sequences in the style of C are also allowed. @xref{C | |
b37052ae | 8608 | Constants, ,C and C@t{++} constants}, for a brief explanation of escape |
c906108c SS |
8609 | sequences. |
8610 | ||
8611 | @item | |
8612 | Enumerated constants consist of an enumerated identifier. | |
8613 | ||
8614 | @item | |
8615 | Boolean constants consist of the identifiers @code{TRUE} and | |
8616 | @code{FALSE}. | |
8617 | ||
8618 | @item | |
8619 | Pointer constants consist of integral values only. | |
8620 | ||
8621 | @item | |
8622 | Set constants are not yet supported. | |
8623 | @end itemize | |
8624 | ||
6d2ebf8b | 8625 | @node M2 Defaults |
c906108c SS |
8626 | @subsubsection Modula-2 defaults |
8627 | @cindex Modula-2 defaults | |
8628 | ||
8629 | If type and range checking are set automatically by @value{GDBN}, they | |
8630 | both default to @code{on} whenever the working language changes to | |
d4f3574e | 8631 | Modula-2. This happens regardless of whether you or @value{GDBN} |
c906108c SS |
8632 | selected the working language. |
8633 | ||
8634 | If you allow @value{GDBN} to set the language automatically, then entering | |
8635 | code compiled from a file whose name ends with @file{.mod} sets the | |
d4f3574e | 8636 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set |
c906108c SS |
8637 | the language automatically}, for further details. |
8638 | ||
6d2ebf8b | 8639 | @node Deviations |
c906108c SS |
8640 | @subsubsection Deviations from standard Modula-2 |
8641 | @cindex Modula-2, deviations from | |
8642 | ||
8643 | A few changes have been made to make Modula-2 programs easier to debug. | |
8644 | This is done primarily via loosening its type strictness: | |
8645 | ||
8646 | @itemize @bullet | |
8647 | @item | |
8648 | Unlike in standard Modula-2, pointer constants can be formed by | |
8649 | integers. This allows you to modify pointer variables during | |
8650 | debugging. (In standard Modula-2, the actual address contained in a | |
8651 | pointer variable is hidden from you; it can only be modified | |
8652 | through direct assignment to another pointer variable or expression that | |
8653 | returned a pointer.) | |
8654 | ||
8655 | @item | |
8656 | C escape sequences can be used in strings and characters to represent | |
8657 | non-printable characters. @value{GDBN} prints out strings with these | |
8658 | escape sequences embedded. Single non-printable characters are | |
8659 | printed using the @samp{CHR(@var{nnn})} format. | |
8660 | ||
8661 | @item | |
8662 | The assignment operator (@code{:=}) returns the value of its right-hand | |
8663 | argument. | |
8664 | ||
8665 | @item | |
8666 | All built-in procedures both modify @emph{and} return their argument. | |
8667 | @end itemize | |
8668 | ||
6d2ebf8b | 8669 | @node M2 Checks |
c906108c SS |
8670 | @subsubsection Modula-2 type and range checks |
8671 | @cindex Modula-2 checks | |
8672 | ||
8673 | @quotation | |
8674 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or | |
8675 | range checking. | |
8676 | @end quotation | |
8677 | @c FIXME remove warning when type/range checks added | |
8678 | ||
8679 | @value{GDBN} considers two Modula-2 variables type equivalent if: | |
8680 | ||
8681 | @itemize @bullet | |
8682 | @item | |
8683 | They are of types that have been declared equivalent via a @code{TYPE | |
8684 | @var{t1} = @var{t2}} statement | |
8685 | ||
8686 | @item | |
8687 | They have been declared on the same line. (Note: This is true of the | |
8688 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) | |
8689 | @end itemize | |
8690 | ||
8691 | As long as type checking is enabled, any attempt to combine variables | |
8692 | whose types are not equivalent is an error. | |
8693 | ||
8694 | Range checking is done on all mathematical operations, assignment, array | |
8695 | index bounds, and all built-in functions and procedures. | |
8696 | ||
6d2ebf8b | 8697 | @node M2 Scope |
c906108c SS |
8698 | @subsubsection The scope operators @code{::} and @code{.} |
8699 | @cindex scope | |
41afff9a | 8700 | @cindex @code{.}, Modula-2 scope operator |
c906108c SS |
8701 | @cindex colon, doubled as scope operator |
8702 | @ifinfo | |
41afff9a | 8703 | @vindex colon-colon@r{, in Modula-2} |
c906108c SS |
8704 | @c Info cannot handle :: but TeX can. |
8705 | @end ifinfo | |
8706 | @iftex | |
41afff9a | 8707 | @vindex ::@r{, in Modula-2} |
c906108c SS |
8708 | @end iftex |
8709 | ||
8710 | There are a few subtle differences between the Modula-2 scope operator | |
8711 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have | |
8712 | similar syntax: | |
8713 | ||
474c8240 | 8714 | @smallexample |
c906108c SS |
8715 | |
8716 | @var{module} . @var{id} | |
8717 | @var{scope} :: @var{id} | |
474c8240 | 8718 | @end smallexample |
c906108c SS |
8719 | |
8720 | @noindent | |
8721 | where @var{scope} is the name of a module or a procedure, | |
8722 | @var{module} the name of a module, and @var{id} is any declared | |
8723 | identifier within your program, except another module. | |
8724 | ||
8725 | Using the @code{::} operator makes @value{GDBN} search the scope | |
8726 | specified by @var{scope} for the identifier @var{id}. If it is not | |
8727 | found in the specified scope, then @value{GDBN} searches all scopes | |
8728 | enclosing the one specified by @var{scope}. | |
8729 | ||
8730 | Using the @code{.} operator makes @value{GDBN} search the current scope for | |
8731 | the identifier specified by @var{id} that was imported from the | |
8732 | definition module specified by @var{module}. With this operator, it is | |
8733 | an error if the identifier @var{id} was not imported from definition | |
8734 | module @var{module}, or if @var{id} is not an identifier in | |
8735 | @var{module}. | |
8736 | ||
6d2ebf8b | 8737 | @node GDB/M2 |
c906108c SS |
8738 | @subsubsection @value{GDBN} and Modula-2 |
8739 | ||
8740 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. | |
8741 | Five subcommands of @code{set print} and @code{show print} apply | |
b37052ae | 8742 | specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle}, |
c906108c | 8743 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four |
b37052ae | 8744 | apply to C@t{++}, and the last to the C @code{union} type, which has no direct |
c906108c SS |
8745 | analogue in Modula-2. |
8746 | ||
8747 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available | |
d4f3574e | 8748 | with any language, is not useful with Modula-2. Its |
c906108c | 8749 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be |
b37052ae | 8750 | created in Modula-2 as they can in C or C@t{++}. However, because an |
c906108c | 8751 | address can be specified by an integral constant, the construct |
d4f3574e | 8752 | @samp{@{@var{type}@}@var{adrexp}} is still useful. |
c906108c SS |
8753 | |
8754 | @cindex @code{#} in Modula-2 | |
8755 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is | |
8756 | interpreted as the beginning of a comment. Use @code{<>} instead. | |
c906108c | 8757 | |
6d2ebf8b | 8758 | @node Symbols |
c906108c SS |
8759 | @chapter Examining the Symbol Table |
8760 | ||
d4f3574e | 8761 | The commands described in this chapter allow you to inquire about the |
c906108c SS |
8762 | symbols (names of variables, functions and types) defined in your |
8763 | program. This information is inherent in the text of your program and | |
8764 | does not change as your program executes. @value{GDBN} finds it in your | |
8765 | program's symbol table, in the file indicated when you started @value{GDBN} | |
8766 | (@pxref{File Options, ,Choosing files}), or by one of the | |
8767 | file-management commands (@pxref{Files, ,Commands to specify files}). | |
8768 | ||
8769 | @cindex symbol names | |
8770 | @cindex names of symbols | |
8771 | @cindex quoting names | |
8772 | Occasionally, you may need to refer to symbols that contain unusual | |
8773 | characters, which @value{GDBN} ordinarily treats as word delimiters. The | |
8774 | most frequent case is in referring to static variables in other | |
8775 | source files (@pxref{Variables,,Program variables}). File names | |
8776 | are recorded in object files as debugging symbols, but @value{GDBN} would | |
8777 | ordinarily parse a typical file name, like @file{foo.c}, as the three words | |
8778 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize | |
8779 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, | |
8780 | ||
474c8240 | 8781 | @smallexample |
c906108c | 8782 | p 'foo.c'::x |
474c8240 | 8783 | @end smallexample |
c906108c SS |
8784 | |
8785 | @noindent | |
8786 | looks up the value of @code{x} in the scope of the file @file{foo.c}. | |
8787 | ||
8788 | @table @code | |
8789 | @kindex info address | |
b37052ae | 8790 | @cindex address of a symbol |
c906108c SS |
8791 | @item info address @var{symbol} |
8792 | Describe where the data for @var{symbol} is stored. For a register | |
8793 | variable, this says which register it is kept in. For a non-register | |
8794 | local variable, this prints the stack-frame offset at which the variable | |
8795 | is always stored. | |
8796 | ||
8797 | Note the contrast with @samp{print &@var{symbol}}, which does not work | |
8798 | at all for a register variable, and for a stack local variable prints | |
8799 | the exact address of the current instantiation of the variable. | |
8800 | ||
3d67e040 | 8801 | @kindex info symbol |
b37052ae | 8802 | @cindex symbol from address |
3d67e040 EZ |
8803 | @item info symbol @var{addr} |
8804 | Print the name of a symbol which is stored at the address @var{addr}. | |
8805 | If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the | |
8806 | nearest symbol and an offset from it: | |
8807 | ||
474c8240 | 8808 | @smallexample |
3d67e040 EZ |
8809 | (@value{GDBP}) info symbol 0x54320 |
8810 | _initialize_vx + 396 in section .text | |
474c8240 | 8811 | @end smallexample |
3d67e040 EZ |
8812 | |
8813 | @noindent | |
8814 | This is the opposite of the @code{info address} command. You can use | |
8815 | it to find out the name of a variable or a function given its address. | |
8816 | ||
c906108c | 8817 | @kindex whatis |
d4f3574e SS |
8818 | @item whatis @var{expr} |
8819 | Print the data type of expression @var{expr}. @var{expr} is not | |
c906108c SS |
8820 | actually evaluated, and any side-effecting operations (such as |
8821 | assignments or function calls) inside it do not take place. | |
8822 | @xref{Expressions, ,Expressions}. | |
8823 | ||
8824 | @item whatis | |
8825 | Print the data type of @code{$}, the last value in the value history. | |
8826 | ||
8827 | @kindex ptype | |
8828 | @item ptype @var{typename} | |
8829 | Print a description of data type @var{typename}. @var{typename} may be | |
7a292a7a SS |
8830 | the name of a type, or for C code it may have the form @samp{class |
8831 | @var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union | |
8832 | @var{union-tag}} or @samp{enum @var{enum-tag}}. | |
c906108c | 8833 | |
d4f3574e | 8834 | @item ptype @var{expr} |
c906108c | 8835 | @itemx ptype |
d4f3574e | 8836 | Print a description of the type of expression @var{expr}. @code{ptype} |
c906108c SS |
8837 | differs from @code{whatis} by printing a detailed description, instead |
8838 | of just the name of the type. | |
8839 | ||
8840 | For example, for this variable declaration: | |
8841 | ||
474c8240 | 8842 | @smallexample |
c906108c | 8843 | struct complex @{double real; double imag;@} v; |
474c8240 | 8844 | @end smallexample |
c906108c SS |
8845 | |
8846 | @noindent | |
8847 | the two commands give this output: | |
8848 | ||
474c8240 | 8849 | @smallexample |
c906108c SS |
8850 | @group |
8851 | (@value{GDBP}) whatis v | |
8852 | type = struct complex | |
8853 | (@value{GDBP}) ptype v | |
8854 | type = struct complex @{ | |
8855 | double real; | |
8856 | double imag; | |
8857 | @} | |
8858 | @end group | |
474c8240 | 8859 | @end smallexample |
c906108c SS |
8860 | |
8861 | @noindent | |
8862 | As with @code{whatis}, using @code{ptype} without an argument refers to | |
8863 | the type of @code{$}, the last value in the value history. | |
8864 | ||
8865 | @kindex info types | |
8866 | @item info types @var{regexp} | |
8867 | @itemx info types | |
d4f3574e | 8868 | Print a brief description of all types whose names match @var{regexp} |
c906108c SS |
8869 | (or all types in your program, if you supply no argument). Each |
8870 | complete typename is matched as though it were a complete line; thus, | |
8871 | @samp{i type value} gives information on all types in your program whose | |
d4f3574e | 8872 | names include the string @code{value}, but @samp{i type ^value$} gives |
c906108c SS |
8873 | information only on types whose complete name is @code{value}. |
8874 | ||
8875 | This command differs from @code{ptype} in two ways: first, like | |
8876 | @code{whatis}, it does not print a detailed description; second, it | |
8877 | lists all source files where a type is defined. | |
8878 | ||
b37052ae EZ |
8879 | @kindex info scope |
8880 | @cindex local variables | |
8881 | @item info scope @var{addr} | |
8882 | List all the variables local to a particular scope. This command | |
8883 | accepts a location---a function name, a source line, or an address | |
8884 | preceded by a @samp{*}, and prints all the variables local to the | |
8885 | scope defined by that location. For example: | |
8886 | ||
8887 | @smallexample | |
8888 | (@value{GDBP}) @b{info scope command_line_handler} | |
8889 | Scope for command_line_handler: | |
8890 | Symbol rl is an argument at stack/frame offset 8, length 4. | |
8891 | Symbol linebuffer is in static storage at address 0x150a18, length 4. | |
8892 | Symbol linelength is in static storage at address 0x150a1c, length 4. | |
8893 | Symbol p is a local variable in register $esi, length 4. | |
8894 | Symbol p1 is a local variable in register $ebx, length 4. | |
8895 | Symbol nline is a local variable in register $edx, length 4. | |
8896 | Symbol repeat is a local variable at frame offset -8, length 4. | |
8897 | @end smallexample | |
8898 | ||
f5c37c66 EZ |
8899 | @noindent |
8900 | This command is especially useful for determining what data to collect | |
8901 | during a @dfn{trace experiment}, see @ref{Tracepoint Actions, | |
8902 | collect}. | |
8903 | ||
c906108c SS |
8904 | @kindex info source |
8905 | @item info source | |
919d772c JB |
8906 | Show information about the current source file---that is, the source file for |
8907 | the function containing the current point of execution: | |
8908 | @itemize @bullet | |
8909 | @item | |
8910 | the name of the source file, and the directory containing it, | |
8911 | @item | |
8912 | the directory it was compiled in, | |
8913 | @item | |
8914 | its length, in lines, | |
8915 | @item | |
8916 | which programming language it is written in, | |
8917 | @item | |
8918 | whether the executable includes debugging information for that file, and | |
8919 | if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and | |
8920 | @item | |
8921 | whether the debugging information includes information about | |
8922 | preprocessor macros. | |
8923 | @end itemize | |
8924 | ||
c906108c SS |
8925 | |
8926 | @kindex info sources | |
8927 | @item info sources | |
8928 | Print the names of all source files in your program for which there is | |
8929 | debugging information, organized into two lists: files whose symbols | |
8930 | have already been read, and files whose symbols will be read when needed. | |
8931 | ||
8932 | @kindex info functions | |
8933 | @item info functions | |
8934 | Print the names and data types of all defined functions. | |
8935 | ||
8936 | @item info functions @var{regexp} | |
8937 | Print the names and data types of all defined functions | |
8938 | whose names contain a match for regular expression @var{regexp}. | |
8939 | Thus, @samp{info fun step} finds all functions whose names | |
8940 | include @code{step}; @samp{info fun ^step} finds those whose names | |
1c5dfdad MS |
8941 | start with @code{step}. If a function name contains characters |
8942 | that conflict with the regular expression language (eg. | |
8943 | @samp{operator*()}), they may be quoted with a backslash. | |
c906108c SS |
8944 | |
8945 | @kindex info variables | |
8946 | @item info variables | |
8947 | Print the names and data types of all variables that are declared | |
6ca652b0 | 8948 | outside of functions (i.e.@: excluding local variables). |
c906108c SS |
8949 | |
8950 | @item info variables @var{regexp} | |
8951 | Print the names and data types of all variables (except for local | |
8952 | variables) whose names contain a match for regular expression | |
8953 | @var{regexp}. | |
8954 | ||
8955 | @ignore | |
8956 | This was never implemented. | |
8957 | @kindex info methods | |
8958 | @item info methods | |
8959 | @itemx info methods @var{regexp} | |
8960 | The @code{info methods} command permits the user to examine all defined | |
b37052ae EZ |
8961 | methods within C@t{++} program, or (with the @var{regexp} argument) a |
8962 | specific set of methods found in the various C@t{++} classes. Many | |
8963 | C@t{++} classes provide a large number of methods. Thus, the output | |
c906108c SS |
8964 | from the @code{ptype} command can be overwhelming and hard to use. The |
8965 | @code{info-methods} command filters the methods, printing only those | |
8966 | which match the regular-expression @var{regexp}. | |
8967 | @end ignore | |
8968 | ||
c906108c SS |
8969 | @cindex reloading symbols |
8970 | Some systems allow individual object files that make up your program to | |
7a292a7a SS |
8971 | be replaced without stopping and restarting your program. For example, |
8972 | in VxWorks you can simply recompile a defective object file and keep on | |
8973 | running. If you are running on one of these systems, you can allow | |
8974 | @value{GDBN} to reload the symbols for automatically relinked modules: | |
c906108c SS |
8975 | |
8976 | @table @code | |
8977 | @kindex set symbol-reloading | |
8978 | @item set symbol-reloading on | |
8979 | Replace symbol definitions for the corresponding source file when an | |
8980 | object file with a particular name is seen again. | |
8981 | ||
8982 | @item set symbol-reloading off | |
6d2ebf8b SS |
8983 | Do not replace symbol definitions when encountering object files of the |
8984 | same name more than once. This is the default state; if you are not | |
8985 | running on a system that permits automatic relinking of modules, you | |
8986 | should leave @code{symbol-reloading} off, since otherwise @value{GDBN} | |
8987 | may discard symbols when linking large programs, that may contain | |
8988 | several modules (from different directories or libraries) with the same | |
8989 | name. | |
c906108c SS |
8990 | |
8991 | @kindex show symbol-reloading | |
8992 | @item show symbol-reloading | |
8993 | Show the current @code{on} or @code{off} setting. | |
8994 | @end table | |
c906108c | 8995 | |
c906108c SS |
8996 | @kindex set opaque-type-resolution |
8997 | @item set opaque-type-resolution on | |
8998 | Tell @value{GDBN} to resolve opaque types. An opaque type is a type | |
8999 | declared as a pointer to a @code{struct}, @code{class}, or | |
9000 | @code{union}---for example, @code{struct MyType *}---that is used in one | |
9001 | source file although the full declaration of @code{struct MyType} is in | |
9002 | another source file. The default is on. | |
9003 | ||
9004 | A change in the setting of this subcommand will not take effect until | |
9005 | the next time symbols for a file are loaded. | |
9006 | ||
9007 | @item set opaque-type-resolution off | |
9008 | Tell @value{GDBN} not to resolve opaque types. In this case, the type | |
9009 | is printed as follows: | |
9010 | @smallexample | |
9011 | @{<no data fields>@} | |
9012 | @end smallexample | |
9013 | ||
9014 | @kindex show opaque-type-resolution | |
9015 | @item show opaque-type-resolution | |
9016 | Show whether opaque types are resolved or not. | |
c906108c SS |
9017 | |
9018 | @kindex maint print symbols | |
9019 | @cindex symbol dump | |
9020 | @kindex maint print psymbols | |
9021 | @cindex partial symbol dump | |
9022 | @item maint print symbols @var{filename} | |
9023 | @itemx maint print psymbols @var{filename} | |
9024 | @itemx maint print msymbols @var{filename} | |
9025 | Write a dump of debugging symbol data into the file @var{filename}. | |
9026 | These commands are used to debug the @value{GDBN} symbol-reading code. Only | |
9027 | symbols with debugging data are included. If you use @samp{maint print | |
9028 | symbols}, @value{GDBN} includes all the symbols for which it has already | |
9029 | collected full details: that is, @var{filename} reflects symbols for | |
9030 | only those files whose symbols @value{GDBN} has read. You can use the | |
9031 | command @code{info sources} to find out which files these are. If you | |
9032 | use @samp{maint print psymbols} instead, the dump shows information about | |
9033 | symbols that @value{GDBN} only knows partially---that is, symbols defined in | |
9034 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, | |
9035 | @samp{maint print msymbols} dumps just the minimal symbol information | |
9036 | required for each object file from which @value{GDBN} has read some symbols. | |
9037 | @xref{Files, ,Commands to specify files}, for a discussion of how | |
9038 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). | |
9039 | @end table | |
9040 | ||
6d2ebf8b | 9041 | @node Altering |
c906108c SS |
9042 | @chapter Altering Execution |
9043 | ||
9044 | Once you think you have found an error in your program, you might want to | |
9045 | find out for certain whether correcting the apparent error would lead to | |
9046 | correct results in the rest of the run. You can find the answer by | |
9047 | experiment, using the @value{GDBN} features for altering execution of the | |
9048 | program. | |
9049 | ||
9050 | For example, you can store new values into variables or memory | |
7a292a7a SS |
9051 | locations, give your program a signal, restart it at a different |
9052 | address, or even return prematurely from a function. | |
c906108c SS |
9053 | |
9054 | @menu | |
9055 | * Assignment:: Assignment to variables | |
9056 | * Jumping:: Continuing at a different address | |
c906108c | 9057 | * Signaling:: Giving your program a signal |
c906108c SS |
9058 | * Returning:: Returning from a function |
9059 | * Calling:: Calling your program's functions | |
9060 | * Patching:: Patching your program | |
9061 | @end menu | |
9062 | ||
6d2ebf8b | 9063 | @node Assignment |
c906108c SS |
9064 | @section Assignment to variables |
9065 | ||
9066 | @cindex assignment | |
9067 | @cindex setting variables | |
9068 | To alter the value of a variable, evaluate an assignment expression. | |
9069 | @xref{Expressions, ,Expressions}. For example, | |
9070 | ||
474c8240 | 9071 | @smallexample |
c906108c | 9072 | print x=4 |
474c8240 | 9073 | @end smallexample |
c906108c SS |
9074 | |
9075 | @noindent | |
9076 | stores the value 4 into the variable @code{x}, and then prints the | |
5d161b24 | 9077 | value of the assignment expression (which is 4). |
c906108c SS |
9078 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more |
9079 | information on operators in supported languages. | |
c906108c SS |
9080 | |
9081 | @kindex set variable | |
9082 | @cindex variables, setting | |
9083 | If you are not interested in seeing the value of the assignment, use the | |
9084 | @code{set} command instead of the @code{print} command. @code{set} is | |
9085 | really the same as @code{print} except that the expression's value is | |
9086 | not printed and is not put in the value history (@pxref{Value History, | |
9087 | ,Value history}). The expression is evaluated only for its effects. | |
9088 | ||
c906108c SS |
9089 | If the beginning of the argument string of the @code{set} command |
9090 | appears identical to a @code{set} subcommand, use the @code{set | |
9091 | variable} command instead of just @code{set}. This command is identical | |
9092 | to @code{set} except for its lack of subcommands. For example, if your | |
9093 | program has a variable @code{width}, you get an error if you try to set | |
9094 | a new value with just @samp{set width=13}, because @value{GDBN} has the | |
9095 | command @code{set width}: | |
9096 | ||
474c8240 | 9097 | @smallexample |
c906108c SS |
9098 | (@value{GDBP}) whatis width |
9099 | type = double | |
9100 | (@value{GDBP}) p width | |
9101 | $4 = 13 | |
9102 | (@value{GDBP}) set width=47 | |
9103 | Invalid syntax in expression. | |
474c8240 | 9104 | @end smallexample |
c906108c SS |
9105 | |
9106 | @noindent | |
9107 | The invalid expression, of course, is @samp{=47}. In | |
9108 | order to actually set the program's variable @code{width}, use | |
9109 | ||
474c8240 | 9110 | @smallexample |
c906108c | 9111 | (@value{GDBP}) set var width=47 |
474c8240 | 9112 | @end smallexample |
53a5351d | 9113 | |
c906108c SS |
9114 | Because the @code{set} command has many subcommands that can conflict |
9115 | with the names of program variables, it is a good idea to use the | |
9116 | @code{set variable} command instead of just @code{set}. For example, if | |
9117 | your program has a variable @code{g}, you run into problems if you try | |
9118 | to set a new value with just @samp{set g=4}, because @value{GDBN} has | |
9119 | the command @code{set gnutarget}, abbreviated @code{set g}: | |
9120 | ||
474c8240 | 9121 | @smallexample |
c906108c SS |
9122 | @group |
9123 | (@value{GDBP}) whatis g | |
9124 | type = double | |
9125 | (@value{GDBP}) p g | |
9126 | $1 = 1 | |
9127 | (@value{GDBP}) set g=4 | |
2df3850c | 9128 | (@value{GDBP}) p g |
c906108c SS |
9129 | $2 = 1 |
9130 | (@value{GDBP}) r | |
9131 | The program being debugged has been started already. | |
9132 | Start it from the beginning? (y or n) y | |
9133 | Starting program: /home/smith/cc_progs/a.out | |
6d2ebf8b SS |
9134 | "/home/smith/cc_progs/a.out": can't open to read symbols: |
9135 | Invalid bfd target. | |
c906108c SS |
9136 | (@value{GDBP}) show g |
9137 | The current BFD target is "=4". | |
9138 | @end group | |
474c8240 | 9139 | @end smallexample |
c906108c SS |
9140 | |
9141 | @noindent | |
9142 | The program variable @code{g} did not change, and you silently set the | |
9143 | @code{gnutarget} to an invalid value. In order to set the variable | |
9144 | @code{g}, use | |
9145 | ||
474c8240 | 9146 | @smallexample |
c906108c | 9147 | (@value{GDBP}) set var g=4 |
474c8240 | 9148 | @end smallexample |
c906108c SS |
9149 | |
9150 | @value{GDBN} allows more implicit conversions in assignments than C; you can | |
9151 | freely store an integer value into a pointer variable or vice versa, | |
9152 | and you can convert any structure to any other structure that is the | |
9153 | same length or shorter. | |
9154 | @comment FIXME: how do structs align/pad in these conversions? | |
9155 | @comment /doc@cygnus.com 18dec1990 | |
9156 | ||
9157 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} | |
9158 | construct to generate a value of specified type at a specified address | |
9159 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers | |
9160 | to memory location @code{0x83040} as an integer (which implies a certain size | |
9161 | and representation in memory), and | |
9162 | ||
474c8240 | 9163 | @smallexample |
c906108c | 9164 | set @{int@}0x83040 = 4 |
474c8240 | 9165 | @end smallexample |
c906108c SS |
9166 | |
9167 | @noindent | |
9168 | stores the value 4 into that memory location. | |
9169 | ||
6d2ebf8b | 9170 | @node Jumping |
c906108c SS |
9171 | @section Continuing at a different address |
9172 | ||
9173 | Ordinarily, when you continue your program, you do so at the place where | |
9174 | it stopped, with the @code{continue} command. You can instead continue at | |
9175 | an address of your own choosing, with the following commands: | |
9176 | ||
9177 | @table @code | |
9178 | @kindex jump | |
9179 | @item jump @var{linespec} | |
9180 | Resume execution at line @var{linespec}. Execution stops again | |
9181 | immediately if there is a breakpoint there. @xref{List, ,Printing | |
9182 | source lines}, for a description of the different forms of | |
9183 | @var{linespec}. It is common practice to use the @code{tbreak} command | |
9184 | in conjunction with @code{jump}. @xref{Set Breaks, ,Setting | |
9185 | breakpoints}. | |
9186 | ||
9187 | The @code{jump} command does not change the current stack frame, or | |
9188 | the stack pointer, or the contents of any memory location or any | |
9189 | register other than the program counter. If line @var{linespec} is in | |
9190 | a different function from the one currently executing, the results may | |
9191 | be bizarre if the two functions expect different patterns of arguments or | |
9192 | of local variables. For this reason, the @code{jump} command requests | |
9193 | confirmation if the specified line is not in the function currently | |
9194 | executing. However, even bizarre results are predictable if you are | |
9195 | well acquainted with the machine-language code of your program. | |
9196 | ||
9197 | @item jump *@var{address} | |
9198 | Resume execution at the instruction at address @var{address}. | |
9199 | @end table | |
9200 | ||
c906108c | 9201 | @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt. |
53a5351d JM |
9202 | On many systems, you can get much the same effect as the @code{jump} |
9203 | command by storing a new value into the register @code{$pc}. The | |
9204 | difference is that this does not start your program running; it only | |
9205 | changes the address of where it @emph{will} run when you continue. For | |
9206 | example, | |
c906108c | 9207 | |
474c8240 | 9208 | @smallexample |
c906108c | 9209 | set $pc = 0x485 |
474c8240 | 9210 | @end smallexample |
c906108c SS |
9211 | |
9212 | @noindent | |
9213 | makes the next @code{continue} command or stepping command execute at | |
9214 | address @code{0x485}, rather than at the address where your program stopped. | |
9215 | @xref{Continuing and Stepping, ,Continuing and stepping}. | |
c906108c SS |
9216 | |
9217 | The most common occasion to use the @code{jump} command is to back | |
9218 | up---perhaps with more breakpoints set---over a portion of a program | |
9219 | that has already executed, in order to examine its execution in more | |
9220 | detail. | |
9221 | ||
c906108c | 9222 | @c @group |
6d2ebf8b | 9223 | @node Signaling |
c906108c SS |
9224 | @section Giving your program a signal |
9225 | ||
9226 | @table @code | |
9227 | @kindex signal | |
9228 | @item signal @var{signal} | |
9229 | Resume execution where your program stopped, but immediately give it the | |
9230 | signal @var{signal}. @var{signal} can be the name or the number of a | |
9231 | signal. For example, on many systems @code{signal 2} and @code{signal | |
9232 | SIGINT} are both ways of sending an interrupt signal. | |
9233 | ||
9234 | Alternatively, if @var{signal} is zero, continue execution without | |
9235 | giving a signal. This is useful when your program stopped on account of | |
9236 | a signal and would ordinary see the signal when resumed with the | |
9237 | @code{continue} command; @samp{signal 0} causes it to resume without a | |
9238 | signal. | |
9239 | ||
9240 | @code{signal} does not repeat when you press @key{RET} a second time | |
9241 | after executing the command. | |
9242 | @end table | |
9243 | @c @end group | |
9244 | ||
9245 | Invoking the @code{signal} command is not the same as invoking the | |
9246 | @code{kill} utility from the shell. Sending a signal with @code{kill} | |
9247 | causes @value{GDBN} to decide what to do with the signal depending on | |
9248 | the signal handling tables (@pxref{Signals}). The @code{signal} command | |
9249 | passes the signal directly to your program. | |
9250 | ||
c906108c | 9251 | |
6d2ebf8b | 9252 | @node Returning |
c906108c SS |
9253 | @section Returning from a function |
9254 | ||
9255 | @table @code | |
9256 | @cindex returning from a function | |
9257 | @kindex return | |
9258 | @item return | |
9259 | @itemx return @var{expression} | |
9260 | You can cancel execution of a function call with the @code{return} | |
9261 | command. If you give an | |
9262 | @var{expression} argument, its value is used as the function's return | |
9263 | value. | |
9264 | @end table | |
9265 | ||
9266 | When you use @code{return}, @value{GDBN} discards the selected stack frame | |
9267 | (and all frames within it). You can think of this as making the | |
9268 | discarded frame return prematurely. If you wish to specify a value to | |
9269 | be returned, give that value as the argument to @code{return}. | |
9270 | ||
9271 | This pops the selected stack frame (@pxref{Selection, ,Selecting a | |
9272 | frame}), and any other frames inside of it, leaving its caller as the | |
9273 | innermost remaining frame. That frame becomes selected. The | |
9274 | specified value is stored in the registers used for returning values | |
9275 | of functions. | |
9276 | ||
9277 | The @code{return} command does not resume execution; it leaves the | |
9278 | program stopped in the state that would exist if the function had just | |
9279 | returned. In contrast, the @code{finish} command (@pxref{Continuing | |
9280 | and Stepping, ,Continuing and stepping}) resumes execution until the | |
9281 | selected stack frame returns naturally. | |
9282 | ||
6d2ebf8b | 9283 | @node Calling |
c906108c SS |
9284 | @section Calling program functions |
9285 | ||
9286 | @cindex calling functions | |
9287 | @kindex call | |
9288 | @table @code | |
9289 | @item call @var{expr} | |
9290 | Evaluate the expression @var{expr} without displaying @code{void} | |
9291 | returned values. | |
9292 | @end table | |
9293 | ||
9294 | You can use this variant of the @code{print} command if you want to | |
9295 | execute a function from your program, but without cluttering the output | |
5d161b24 DB |
9296 | with @code{void} returned values. If the result is not void, it |
9297 | is printed and saved in the value history. | |
c906108c | 9298 | |
6d2ebf8b | 9299 | @node Patching |
c906108c | 9300 | @section Patching programs |
7a292a7a | 9301 | |
c906108c SS |
9302 | @cindex patching binaries |
9303 | @cindex writing into executables | |
c906108c | 9304 | @cindex writing into corefiles |
c906108c | 9305 | |
7a292a7a SS |
9306 | By default, @value{GDBN} opens the file containing your program's |
9307 | executable code (or the corefile) read-only. This prevents accidental | |
9308 | alterations to machine code; but it also prevents you from intentionally | |
9309 | patching your program's binary. | |
c906108c SS |
9310 | |
9311 | If you'd like to be able to patch the binary, you can specify that | |
9312 | explicitly with the @code{set write} command. For example, you might | |
9313 | want to turn on internal debugging flags, or even to make emergency | |
9314 | repairs. | |
9315 | ||
9316 | @table @code | |
9317 | @kindex set write | |
9318 | @item set write on | |
9319 | @itemx set write off | |
7a292a7a SS |
9320 | If you specify @samp{set write on}, @value{GDBN} opens executable and |
9321 | core files for both reading and writing; if you specify @samp{set write | |
c906108c SS |
9322 | off} (the default), @value{GDBN} opens them read-only. |
9323 | ||
9324 | If you have already loaded a file, you must load it again (using the | |
7a292a7a SS |
9325 | @code{exec-file} or @code{core-file} command) after changing @code{set |
9326 | write}, for your new setting to take effect. | |
c906108c SS |
9327 | |
9328 | @item show write | |
9329 | @kindex show write | |
7a292a7a SS |
9330 | Display whether executable files and core files are opened for writing |
9331 | as well as reading. | |
c906108c SS |
9332 | @end table |
9333 | ||
6d2ebf8b | 9334 | @node GDB Files |
c906108c SS |
9335 | @chapter @value{GDBN} Files |
9336 | ||
7a292a7a SS |
9337 | @value{GDBN} needs to know the file name of the program to be debugged, |
9338 | both in order to read its symbol table and in order to start your | |
9339 | program. To debug a core dump of a previous run, you must also tell | |
9340 | @value{GDBN} the name of the core dump file. | |
c906108c SS |
9341 | |
9342 | @menu | |
9343 | * Files:: Commands to specify files | |
5b5d99cf | 9344 | * Separate Debug Files:: Debugging information in separate files |
c906108c SS |
9345 | * Symbol Errors:: Errors reading symbol files |
9346 | @end menu | |
9347 | ||
6d2ebf8b | 9348 | @node Files |
c906108c | 9349 | @section Commands to specify files |
c906108c | 9350 | |
7a292a7a | 9351 | @cindex symbol table |
c906108c | 9352 | @cindex core dump file |
7a292a7a SS |
9353 | |
9354 | You may want to specify executable and core dump file names. The usual | |
9355 | way to do this is at start-up time, using the arguments to | |
9356 | @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and | |
9357 | Out of @value{GDBN}}). | |
c906108c SS |
9358 | |
9359 | Occasionally it is necessary to change to a different file during a | |
9360 | @value{GDBN} session. Or you may run @value{GDBN} and forget to specify | |
9361 | a file you want to use. In these situations the @value{GDBN} commands | |
9362 | to specify new files are useful. | |
9363 | ||
9364 | @table @code | |
9365 | @cindex executable file | |
9366 | @kindex file | |
9367 | @item file @var{filename} | |
9368 | Use @var{filename} as the program to be debugged. It is read for its | |
9369 | symbols and for the contents of pure memory. It is also the program | |
9370 | executed when you use the @code{run} command. If you do not specify a | |
5d161b24 DB |
9371 | directory and the file is not found in the @value{GDBN} working directory, |
9372 | @value{GDBN} uses the environment variable @code{PATH} as a list of | |
9373 | directories to search, just as the shell does when looking for a program | |
9374 | to run. You can change the value of this variable, for both @value{GDBN} | |
c906108c SS |
9375 | and your program, using the @code{path} command. |
9376 | ||
6d2ebf8b | 9377 | On systems with memory-mapped files, an auxiliary file named |
c906108c SS |
9378 | @file{@var{filename}.syms} may hold symbol table information for |
9379 | @var{filename}. If so, @value{GDBN} maps in the symbol table from | |
9380 | @file{@var{filename}.syms}, starting up more quickly. See the | |
9381 | descriptions of the file options @samp{-mapped} and @samp{-readnow} | |
9382 | (available on the command line, and with the commands @code{file}, | |
5d161b24 | 9383 | @code{symbol-file}, or @code{add-symbol-file}, described below), |
c906108c | 9384 | for more information. |
c906108c SS |
9385 | |
9386 | @item file | |
9387 | @code{file} with no argument makes @value{GDBN} discard any information it | |
9388 | has on both executable file and the symbol table. | |
9389 | ||
9390 | @kindex exec-file | |
9391 | @item exec-file @r{[} @var{filename} @r{]} | |
9392 | Specify that the program to be run (but not the symbol table) is found | |
9393 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} | |
9394 | if necessary to locate your program. Omitting @var{filename} means to | |
9395 | discard information on the executable file. | |
9396 | ||
9397 | @kindex symbol-file | |
9398 | @item symbol-file @r{[} @var{filename} @r{]} | |
9399 | Read symbol table information from file @var{filename}. @code{PATH} is | |
9400 | searched when necessary. Use the @code{file} command to get both symbol | |
9401 | table and program to run from the same file. | |
9402 | ||
9403 | @code{symbol-file} with no argument clears out @value{GDBN} information on your | |
9404 | program's symbol table. | |
9405 | ||
5d161b24 | 9406 | The @code{symbol-file} command causes @value{GDBN} to forget the contents |
c906108c SS |
9407 | of its convenience variables, the value history, and all breakpoints and |
9408 | auto-display expressions. This is because they may contain pointers to | |
9409 | the internal data recording symbols and data types, which are part of | |
9410 | the old symbol table data being discarded inside @value{GDBN}. | |
9411 | ||
9412 | @code{symbol-file} does not repeat if you press @key{RET} again after | |
9413 | executing it once. | |
9414 | ||
9415 | When @value{GDBN} is configured for a particular environment, it | |
9416 | understands debugging information in whatever format is the standard | |
9417 | generated for that environment; you may use either a @sc{gnu} compiler, or | |
9418 | other compilers that adhere to the local conventions. | |
c906108c SS |
9419 | Best results are usually obtained from @sc{gnu} compilers; for example, |
9420 | using @code{@value{GCC}} you can generate debugging information for | |
9421 | optimized code. | |
c906108c SS |
9422 | |
9423 | For most kinds of object files, with the exception of old SVR3 systems | |
9424 | using COFF, the @code{symbol-file} command does not normally read the | |
9425 | symbol table in full right away. Instead, it scans the symbol table | |
9426 | quickly to find which source files and which symbols are present. The | |
9427 | details are read later, one source file at a time, as they are needed. | |
9428 | ||
9429 | The purpose of this two-stage reading strategy is to make @value{GDBN} | |
9430 | start up faster. For the most part, it is invisible except for | |
9431 | occasional pauses while the symbol table details for a particular source | |
9432 | file are being read. (The @code{set verbose} command can turn these | |
9433 | pauses into messages if desired. @xref{Messages/Warnings, ,Optional | |
9434 | warnings and messages}.) | |
9435 | ||
c906108c SS |
9436 | We have not implemented the two-stage strategy for COFF yet. When the |
9437 | symbol table is stored in COFF format, @code{symbol-file} reads the | |
9438 | symbol table data in full right away. Note that ``stabs-in-COFF'' | |
9439 | still does the two-stage strategy, since the debug info is actually | |
9440 | in stabs format. | |
9441 | ||
9442 | @kindex readnow | |
9443 | @cindex reading symbols immediately | |
9444 | @cindex symbols, reading immediately | |
9445 | @kindex mapped | |
9446 | @cindex memory-mapped symbol file | |
9447 | @cindex saving symbol table | |
9448 | @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
9449 | @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
9450 | You can override the @value{GDBN} two-stage strategy for reading symbol | |
9451 | tables by using the @samp{-readnow} option with any of the commands that | |
9452 | load symbol table information, if you want to be sure @value{GDBN} has the | |
5d161b24 | 9453 | entire symbol table available. |
c906108c | 9454 | |
c906108c SS |
9455 | If memory-mapped files are available on your system through the |
9456 | @code{mmap} system call, you can use another option, @samp{-mapped}, to | |
9457 | cause @value{GDBN} to write the symbols for your program into a reusable | |
9458 | file. Future @value{GDBN} debugging sessions map in symbol information | |
9459 | from this auxiliary symbol file (if the program has not changed), rather | |
9460 | than spending time reading the symbol table from the executable | |
9461 | program. Using the @samp{-mapped} option has the same effect as | |
9462 | starting @value{GDBN} with the @samp{-mapped} command-line option. | |
9463 | ||
9464 | You can use both options together, to make sure the auxiliary symbol | |
9465 | file has all the symbol information for your program. | |
9466 | ||
9467 | The auxiliary symbol file for a program called @var{myprog} is called | |
9468 | @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer | |
9469 | than the corresponding executable), @value{GDBN} always attempts to use | |
9470 | it when you debug @var{myprog}; no special options or commands are | |
9471 | needed. | |
9472 | ||
9473 | The @file{.syms} file is specific to the host machine where you run | |
9474 | @value{GDBN}. It holds an exact image of the internal @value{GDBN} | |
9475 | symbol table. It cannot be shared across multiple host platforms. | |
c906108c SS |
9476 | |
9477 | @c FIXME: for now no mention of directories, since this seems to be in | |
9478 | @c flux. 13mar1992 status is that in theory GDB would look either in | |
9479 | @c current dir or in same dir as myprog; but issues like competing | |
9480 | @c GDB's, or clutter in system dirs, mean that in practice right now | |
9481 | @c only current dir is used. FFish says maybe a special GDB hierarchy | |
9482 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol | |
9483 | @c files. | |
9484 | ||
9485 | @kindex core | |
9486 | @kindex core-file | |
9487 | @item core-file @r{[} @var{filename} @r{]} | |
9488 | Specify the whereabouts of a core dump file to be used as the ``contents | |
9489 | of memory''. Traditionally, core files contain only some parts of the | |
9490 | address space of the process that generated them; @value{GDBN} can access the | |
9491 | executable file itself for other parts. | |
9492 | ||
9493 | @code{core-file} with no argument specifies that no core file is | |
9494 | to be used. | |
9495 | ||
9496 | Note that the core file is ignored when your program is actually running | |
7a292a7a SS |
9497 | under @value{GDBN}. So, if you have been running your program and you |
9498 | wish to debug a core file instead, you must kill the subprocess in which | |
9499 | the program is running. To do this, use the @code{kill} command | |
c906108c | 9500 | (@pxref{Kill Process, ,Killing the child process}). |
c906108c | 9501 | |
c906108c SS |
9502 | @kindex add-symbol-file |
9503 | @cindex dynamic linking | |
9504 | @item add-symbol-file @var{filename} @var{address} | |
9505 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
17d9d558 | 9506 | @itemx add-symbol-file @var{filename} @r{-s}@var{section} @var{address} @dots{} |
96a2c332 SS |
9507 | The @code{add-symbol-file} command reads additional symbol table |
9508 | information from the file @var{filename}. You would use this command | |
9509 | when @var{filename} has been dynamically loaded (by some other means) | |
9510 | into the program that is running. @var{address} should be the memory | |
9511 | address at which the file has been loaded; @value{GDBN} cannot figure | |
d167840f EZ |
9512 | this out for itself. You can additionally specify an arbitrary number |
9513 | of @samp{@r{-s}@var{section} @var{address}} pairs, to give an explicit | |
9514 | section name and base address for that section. You can specify any | |
9515 | @var{address} as an expression. | |
c906108c SS |
9516 | |
9517 | The symbol table of the file @var{filename} is added to the symbol table | |
9518 | originally read with the @code{symbol-file} command. You can use the | |
96a2c332 SS |
9519 | @code{add-symbol-file} command any number of times; the new symbol data |
9520 | thus read keeps adding to the old. To discard all old symbol data | |
9521 | instead, use the @code{symbol-file} command without any arguments. | |
c906108c | 9522 | |
17d9d558 JB |
9523 | @cindex relocatable object files, reading symbols from |
9524 | @cindex object files, relocatable, reading symbols from | |
9525 | @cindex reading symbols from relocatable object files | |
9526 | @cindex symbols, reading from relocatable object files | |
9527 | @cindex @file{.o} files, reading symbols from | |
9528 | Although @var{filename} is typically a shared library file, an | |
9529 | executable file, or some other object file which has been fully | |
9530 | relocated for loading into a process, you can also load symbolic | |
9531 | information from relocatable @file{.o} files, as long as: | |
9532 | ||
9533 | @itemize @bullet | |
9534 | @item | |
9535 | the file's symbolic information refers only to linker symbols defined in | |
9536 | that file, not to symbols defined by other object files, | |
9537 | @item | |
9538 | every section the file's symbolic information refers to has actually | |
9539 | been loaded into the inferior, as it appears in the file, and | |
9540 | @item | |
9541 | you can determine the address at which every section was loaded, and | |
9542 | provide these to the @code{add-symbol-file} command. | |
9543 | @end itemize | |
9544 | ||
9545 | @noindent | |
9546 | Some embedded operating systems, like Sun Chorus and VxWorks, can load | |
9547 | relocatable files into an already running program; such systems | |
9548 | typically make the requirements above easy to meet. However, it's | |
9549 | important to recognize that many native systems use complex link | |
9550 | procedures (@code{.linkonce} section factoring and C++ constructor table | |
9551 | assembly, for example) that make the requirements difficult to meet. In | |
9552 | general, one cannot assume that using @code{add-symbol-file} to read a | |
9553 | relocatable object file's symbolic information will have the same effect | |
9554 | as linking the relocatable object file into the program in the normal | |
9555 | way. | |
9556 | ||
c906108c SS |
9557 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. |
9558 | ||
9559 | You can use the @samp{-mapped} and @samp{-readnow} options just as with | |
9560 | the @code{symbol-file} command, to change how @value{GDBN} manages the symbol | |
9561 | table information for @var{filename}. | |
9562 | ||
9563 | @kindex add-shared-symbol-file | |
9564 | @item add-shared-symbol-file | |
9565 | The @code{add-shared-symbol-file} command can be used only under Harris' CXUX | |
5d161b24 DB |
9566 | operating system for the Motorola 88k. @value{GDBN} automatically looks for |
9567 | shared libraries, however if @value{GDBN} does not find yours, you can run | |
c906108c | 9568 | @code{add-shared-symbol-file}. It takes no arguments. |
c906108c | 9569 | |
c906108c SS |
9570 | @kindex section |
9571 | @item section | |
5d161b24 DB |
9572 | The @code{section} command changes the base address of section SECTION of |
9573 | the exec file to ADDR. This can be used if the exec file does not contain | |
9574 | section addresses, (such as in the a.out format), or when the addresses | |
9575 | specified in the file itself are wrong. Each section must be changed | |
d4f3574e SS |
9576 | separately. The @code{info files} command, described below, lists all |
9577 | the sections and their addresses. | |
c906108c SS |
9578 | |
9579 | @kindex info files | |
9580 | @kindex info target | |
9581 | @item info files | |
9582 | @itemx info target | |
7a292a7a SS |
9583 | @code{info files} and @code{info target} are synonymous; both print the |
9584 | current target (@pxref{Targets, ,Specifying a Debugging Target}), | |
9585 | including the names of the executable and core dump files currently in | |
9586 | use by @value{GDBN}, and the files from which symbols were loaded. The | |
9587 | command @code{help target} lists all possible targets rather than | |
9588 | current ones. | |
9589 | ||
fe95c787 MS |
9590 | @kindex maint info sections |
9591 | @item maint info sections | |
9592 | Another command that can give you extra information about program sections | |
9593 | is @code{maint info sections}. In addition to the section information | |
9594 | displayed by @code{info files}, this command displays the flags and file | |
9595 | offset of each section in the executable and core dump files. In addition, | |
9596 | @code{maint info sections} provides the following command options (which | |
9597 | may be arbitrarily combined): | |
9598 | ||
9599 | @table @code | |
9600 | @item ALLOBJ | |
9601 | Display sections for all loaded object files, including shared libraries. | |
9602 | @item @var{sections} | |
6600abed | 9603 | Display info only for named @var{sections}. |
fe95c787 MS |
9604 | @item @var{section-flags} |
9605 | Display info only for sections for which @var{section-flags} are true. | |
9606 | The section flags that @value{GDBN} currently knows about are: | |
9607 | @table @code | |
9608 | @item ALLOC | |
9609 | Section will have space allocated in the process when loaded. | |
9610 | Set for all sections except those containing debug information. | |
9611 | @item LOAD | |
9612 | Section will be loaded from the file into the child process memory. | |
9613 | Set for pre-initialized code and data, clear for @code{.bss} sections. | |
9614 | @item RELOC | |
9615 | Section needs to be relocated before loading. | |
9616 | @item READONLY | |
9617 | Section cannot be modified by the child process. | |
9618 | @item CODE | |
9619 | Section contains executable code only. | |
6600abed | 9620 | @item DATA |
fe95c787 MS |
9621 | Section contains data only (no executable code). |
9622 | @item ROM | |
9623 | Section will reside in ROM. | |
9624 | @item CONSTRUCTOR | |
9625 | Section contains data for constructor/destructor lists. | |
9626 | @item HAS_CONTENTS | |
9627 | Section is not empty. | |
9628 | @item NEVER_LOAD | |
9629 | An instruction to the linker to not output the section. | |
9630 | @item COFF_SHARED_LIBRARY | |
9631 | A notification to the linker that the section contains | |
9632 | COFF shared library information. | |
9633 | @item IS_COMMON | |
9634 | Section contains common symbols. | |
9635 | @end table | |
9636 | @end table | |
6763aef9 MS |
9637 | @kindex set trust-readonly-sections |
9638 | @item set trust-readonly-sections on | |
9639 | Tell @value{GDBN} that readonly sections in your object file | |
6ca652b0 | 9640 | really are read-only (i.e.@: that their contents will not change). |
6763aef9 MS |
9641 | In that case, @value{GDBN} can fetch values from these sections |
9642 | out of the object file, rather than from the target program. | |
9643 | For some targets (notably embedded ones), this can be a significant | |
9644 | enhancement to debugging performance. | |
9645 | ||
9646 | The default is off. | |
9647 | ||
9648 | @item set trust-readonly-sections off | |
15110bc3 | 9649 | Tell @value{GDBN} not to trust readonly sections. This means that |
6763aef9 MS |
9650 | the contents of the section might change while the program is running, |
9651 | and must therefore be fetched from the target when needed. | |
c906108c SS |
9652 | @end table |
9653 | ||
9654 | All file-specifying commands allow both absolute and relative file names | |
9655 | as arguments. @value{GDBN} always converts the file name to an absolute file | |
9656 | name and remembers it that way. | |
9657 | ||
c906108c | 9658 | @cindex shared libraries |
c906108c SS |
9659 | @value{GDBN} supports HP-UX, SunOS, SVr4, Irix 5, and IBM RS/6000 shared |
9660 | libraries. | |
53a5351d | 9661 | |
c906108c SS |
9662 | @value{GDBN} automatically loads symbol definitions from shared libraries |
9663 | when you use the @code{run} command, or when you examine a core file. | |
9664 | (Before you issue the @code{run} command, @value{GDBN} does not understand | |
9665 | references to a function in a shared library, however---unless you are | |
9666 | debugging a core file). | |
53a5351d JM |
9667 | |
9668 | On HP-UX, if the program loads a library explicitly, @value{GDBN} | |
9669 | automatically loads the symbols at the time of the @code{shl_load} call. | |
9670 | ||
c906108c SS |
9671 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
9672 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared | |
9673 | @c FIXME...lib; check this from time to time when updating manual | |
9674 | ||
b7209cb4 FF |
9675 | There are times, however, when you may wish to not automatically load |
9676 | symbol definitions from shared libraries, such as when they are | |
9677 | particularly large or there are many of them. | |
9678 | ||
9679 | To control the automatic loading of shared library symbols, use the | |
9680 | commands: | |
9681 | ||
9682 | @table @code | |
9683 | @kindex set auto-solib-add | |
9684 | @item set auto-solib-add @var{mode} | |
9685 | If @var{mode} is @code{on}, symbols from all shared object libraries | |
9686 | will be loaded automatically when the inferior begins execution, you | |
9687 | attach to an independently started inferior, or when the dynamic linker | |
9688 | informs @value{GDBN} that a new library has been loaded. If @var{mode} | |
9689 | is @code{off}, symbols must be loaded manually, using the | |
9690 | @code{sharedlibrary} command. The default value is @code{on}. | |
9691 | ||
9692 | @kindex show auto-solib-add | |
9693 | @item show auto-solib-add | |
9694 | Display the current autoloading mode. | |
9695 | @end table | |
9696 | ||
9697 | To explicitly load shared library symbols, use the @code{sharedlibrary} | |
9698 | command: | |
9699 | ||
c906108c SS |
9700 | @table @code |
9701 | @kindex info sharedlibrary | |
9702 | @kindex info share | |
9703 | @item info share | |
9704 | @itemx info sharedlibrary | |
9705 | Print the names of the shared libraries which are currently loaded. | |
9706 | ||
9707 | @kindex sharedlibrary | |
9708 | @kindex share | |
9709 | @item sharedlibrary @var{regex} | |
9710 | @itemx share @var{regex} | |
c906108c SS |
9711 | Load shared object library symbols for files matching a |
9712 | Unix regular expression. | |
9713 | As with files loaded automatically, it only loads shared libraries | |
9714 | required by your program for a core file or after typing @code{run}. If | |
9715 | @var{regex} is omitted all shared libraries required by your program are | |
9716 | loaded. | |
9717 | @end table | |
9718 | ||
b7209cb4 FF |
9719 | On some systems, such as HP-UX systems, @value{GDBN} supports |
9720 | autoloading shared library symbols until a limiting threshold size is | |
9721 | reached. This provides the benefit of allowing autoloading to remain on | |
9722 | by default, but avoids autoloading excessively large shared libraries, | |
9723 | up to a threshold that is initially set, but which you can modify if you | |
9724 | wish. | |
c906108c SS |
9725 | |
9726 | Beyond that threshold, symbols from shared libraries must be explicitly | |
d4f3574e SS |
9727 | loaded. To load these symbols, use the command @code{sharedlibrary |
9728 | @var{filename}}. The base address of the shared library is determined | |
c906108c SS |
9729 | automatically by @value{GDBN} and need not be specified. |
9730 | ||
9731 | To display or set the threshold, use the commands: | |
9732 | ||
9733 | @table @code | |
b7209cb4 FF |
9734 | @kindex set auto-solib-limit |
9735 | @item set auto-solib-limit @var{threshold} | |
9736 | Set the autoloading size threshold, in an integral number of megabytes. | |
9737 | If @var{threshold} is nonzero and shared library autoloading is enabled, | |
9738 | symbols from all shared object libraries will be loaded until the total | |
9739 | size of the loaded shared library symbols exceeds this threshold. | |
c906108c | 9740 | Otherwise, symbols must be loaded manually, using the |
6ca652b0 | 9741 | @code{sharedlibrary} command. The default threshold is 100 (i.e.@: 100 |
b7209cb4 | 9742 | Mb). |
c906108c | 9743 | |
b7209cb4 FF |
9744 | @kindex show auto-solib-limit |
9745 | @item show auto-solib-limit | |
c906108c SS |
9746 | Display the current autoloading size threshold, in megabytes. |
9747 | @end table | |
c906108c | 9748 | |
f5ebfba0 DJ |
9749 | Shared libraries are also supported in many cross or remote debugging |
9750 | configurations. A copy of the target's libraries need to be present on the | |
9751 | host system; they need to be the same as the target libraries, although the | |
9752 | copies on the target can be stripped as long as the copies on the host are | |
9753 | not. | |
9754 | ||
9755 | You need to tell @value{GDBN} where the target libraries are, so that it can | |
9756 | load the correct copies---otherwise, it may try to load the host's libraries. | |
9757 | @value{GDBN} has two variables to specify the search directories for target | |
9758 | libraries. | |
9759 | ||
9760 | @table @code | |
9761 | @kindex set solib-absolute-prefix | |
9762 | @item set solib-absolute-prefix @var{path} | |
9763 | If this variable is set, @var{path} will be used as a prefix for any | |
9764 | absolute shared library paths; many runtime loaders store the absolute | |
9765 | paths to the shared library in the target program's memory. If you use | |
9766 | @samp{solib-absolute-prefix} to find shared libraries, they need to be laid | |
9767 | out in the same way that they are on the target, with e.g.@: a | |
9768 | @file{/usr/lib} hierarchy under @var{path}. | |
9769 | ||
9770 | You can set the default value of @samp{solib-absolute-prefix} by using the | |
9771 | configure-time @samp{--with-sysroot} option. | |
9772 | ||
9773 | @kindex show solib-absolute-prefix | |
9774 | @item show solib-absolute-prefix | |
9775 | Display the current shared library prefix. | |
9776 | ||
9777 | @kindex set solib-search-path | |
9778 | @item set solib-search-path @var{path} | |
9779 | If this variable is set, @var{path} is a colon-separated list of directories | |
9780 | to search for shared libraries. @samp{solib-search-path} is used after | |
9781 | @samp{solib-absolute-prefix} fails to locate the library, or if the path to | |
9782 | the library is relative instead of absolute. If you want to use | |
9783 | @samp{solib-search-path} instead of @samp{solib-absolute-prefix}, be sure to | |
9784 | set @samp{solib-absolute-prefix} to a nonexistant directory to prevent | |
9785 | @value{GDBN} from finding your host's libraries. | |
9786 | ||
9787 | @kindex show solib-search-path | |
9788 | @item show solib-search-path | |
9789 | Display the current shared library search path. | |
9790 | @end table | |
9791 | ||
5b5d99cf JB |
9792 | |
9793 | @node Separate Debug Files | |
9794 | @section Debugging Information in Separate Files | |
9795 | @cindex separate debugging information files | |
9796 | @cindex debugging information in separate files | |
9797 | @cindex @file{.debug} subdirectories | |
9798 | @cindex debugging information directory, global | |
9799 | @cindex global debugging information directory | |
9800 | ||
9801 | @value{GDBN} allows you to put a program's debugging information in a | |
9802 | file separate from the executable itself, in a way that allows | |
9803 | @value{GDBN} to find and load the debugging information automatically. | |
9804 | Since debugging information can be very large --- sometimes larger | |
9805 | than the executable code itself --- some systems distribute debugging | |
9806 | information for their executables in separate files, which users can | |
9807 | install only when they need to debug a problem. | |
9808 | ||
9809 | If an executable's debugging information has been extracted to a | |
9810 | separate file, the executable should contain a @dfn{debug link} giving | |
9811 | the name of the debugging information file (with no directory | |
9812 | components), and a checksum of its contents. (The exact form of a | |
9813 | debug link is described below.) If the full name of the directory | |
9814 | containing the executable is @var{execdir}, and the executable has a | |
9815 | debug link that specifies the name @var{debugfile}, then @value{GDBN} | |
9816 | will automatically search for the debugging information file in three | |
9817 | places: | |
9818 | ||
9819 | @itemize @bullet | |
9820 | @item | |
9821 | the directory containing the executable file (that is, it will look | |
9822 | for a file named @file{@var{execdir}/@var{debugfile}}, | |
9823 | @item | |
9824 | a subdirectory of that directory named @file{.debug} (that is, the | |
9825 | file @file{@var{execdir}/.debug/@var{debugfile}}, and | |
9826 | @item | |
9827 | a subdirectory of the global debug file directory that includes the | |
9828 | executable's full path, and the name from the link (that is, the file | |
9829 | @file{@var{globaldebugdir}/@var{execdir}/@var{debugfile}}, where | |
9830 | @var{globaldebugdir} is the global debug file directory, and | |
9831 | @var{execdir} has been turned into a relative path). | |
9832 | @end itemize | |
9833 | @noindent | |
9834 | @value{GDBN} checks under each of these names for a debugging | |
9835 | information file whose checksum matches that given in the link, and | |
9836 | reads the debugging information from the first one it finds. | |
9837 | ||
9838 | So, for example, if you ask @value{GDBN} to debug @file{/usr/bin/ls}, | |
9839 | which has a link containing the name @file{ls.debug}, and the global | |
9840 | debug directory is @file{/usr/lib/debug}, then @value{GDBN} will look | |
9841 | for debug information in @file{/usr/bin/ls.debug}, | |
9842 | @file{/usr/bin/.debug/ls.debug}, and | |
9843 | @file{/usr/lib/debug/usr/bin/ls.debug}. | |
9844 | ||
9845 | You can set the global debugging info directory's name, and view the | |
9846 | name @value{GDBN} is currently using. | |
9847 | ||
9848 | @table @code | |
9849 | ||
9850 | @kindex set debug-file-directory | |
9851 | @item set debug-file-directory @var{directory} | |
9852 | Set the directory which @value{GDBN} searches for separate debugging | |
9853 | information files to @var{directory}. | |
9854 | ||
9855 | @kindex show debug-file-directory | |
9856 | @item show debug-file-directory | |
9857 | Show the directory @value{GDBN} searches for separate debugging | |
9858 | information files. | |
9859 | ||
9860 | @end table | |
9861 | ||
9862 | @cindex @code{.gnu_debuglink} sections | |
9863 | @cindex debug links | |
9864 | A debug link is a special section of the executable file named | |
9865 | @code{.gnu_debuglink}. The section must contain: | |
9866 | ||
9867 | @itemize | |
9868 | @item | |
9869 | A filename, with any leading directory components removed, followed by | |
9870 | a zero byte, | |
9871 | @item | |
9872 | zero to three bytes of padding, as needed to reach the next four-byte | |
9873 | boundary within the section, and | |
9874 | @item | |
9875 | a four-byte CRC checksum, stored in the same endianness used for the | |
9876 | executable file itself. The checksum is computed on the debugging | |
9877 | information file's full contents by the function given below, passing | |
9878 | zero as the @var{crc} argument. | |
9879 | @end itemize | |
9880 | ||
9881 | Any executable file format can carry a debug link, as long as it can | |
9882 | contain a section named @code{.gnu_debuglink} with the contents | |
9883 | described above. | |
9884 | ||
9885 | The debugging information file itself should be an ordinary | |
9886 | executable, containing a full set of linker symbols, sections, and | |
9887 | debugging information. The sections of the debugging information file | |
9888 | should have the same names, addresses and sizes as the original file, | |
9889 | but they need not contain any data --- much like a @code{.bss} section | |
9890 | in an ordinary executable. | |
9891 | ||
9892 | As of December 2002, there is no standard GNU utility to produce | |
9893 | separated executable / debugging information file pairs. Ulrich | |
9894 | Drepper's @file{elfutils} package, starting with version 0.53, | |
9895 | contains a version of the @code{strip} command such that the command | |
9896 | @kbd{strip foo -f foo.debug} removes the debugging information from | |
9897 | the executable file @file{foo}, places it in the file | |
9898 | @file{foo.debug}, and leaves behind a debug link in @file{foo}. | |
9899 | ||
9900 | Since there are many different ways to compute CRC's (different | |
9901 | polynomials, reversals, byte ordering, etc.), the simplest way to | |
9902 | describe the CRC used in @code{.gnu_debuglink} sections is to give the | |
9903 | complete code for a function that computes it: | |
9904 | ||
9905 | @kindex @code{gnu_debuglink_crc32} | |
9906 | @smallexample | |
9907 | unsigned long | |
9908 | gnu_debuglink_crc32 (unsigned long crc, | |
9909 | unsigned char *buf, size_t len) | |
9910 | @{ | |
9911 | static const unsigned long crc32_table[256] = | |
9912 | @{ | |
9913 | 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, | |
9914 | 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, | |
9915 | 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, | |
9916 | 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, | |
9917 | 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, | |
9918 | 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, | |
9919 | 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, | |
9920 | 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, | |
9921 | 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, | |
9922 | 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, | |
9923 | 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, | |
9924 | 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, | |
9925 | 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, | |
9926 | 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, | |
9927 | 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, | |
9928 | 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, | |
9929 | 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, | |
9930 | 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, | |
9931 | 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, | |
9932 | 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, | |
9933 | 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, | |
9934 | 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, | |
9935 | 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, | |
9936 | 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, | |
9937 | 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, | |
9938 | 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, | |
9939 | 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, | |
9940 | 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, | |
9941 | 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, | |
9942 | 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, | |
9943 | 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, | |
9944 | 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, | |
9945 | 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, | |
9946 | 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, | |
9947 | 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, | |
9948 | 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, | |
9949 | 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, | |
9950 | 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, | |
9951 | 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, | |
9952 | 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, | |
9953 | 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, | |
9954 | 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, | |
9955 | 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, | |
9956 | 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, | |
9957 | 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, | |
9958 | 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, | |
9959 | 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, | |
9960 | 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, | |
9961 | 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, | |
9962 | 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, | |
9963 | 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, | |
9964 | 0x2d02ef8d | |
9965 | @}; | |
9966 | unsigned char *end; | |
9967 | ||
9968 | crc = ~crc & 0xffffffff; | |
9969 | for (end = buf + len; buf < end; ++buf) | |
9970 | crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8); | |
9971 | return ~crc & 0xffffffff;; | |
9972 | @} | |
9973 | @end smallexample | |
9974 | ||
9975 | ||
6d2ebf8b | 9976 | @node Symbol Errors |
c906108c SS |
9977 | @section Errors reading symbol files |
9978 | ||
9979 | While reading a symbol file, @value{GDBN} occasionally encounters problems, | |
9980 | such as symbol types it does not recognize, or known bugs in compiler | |
9981 | output. By default, @value{GDBN} does not notify you of such problems, since | |
9982 | they are relatively common and primarily of interest to people | |
9983 | debugging compilers. If you are interested in seeing information | |
9984 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print | |
9985 | only one message about each such type of problem, no matter how many | |
9986 | times the problem occurs; or you can ask @value{GDBN} to print more messages, | |
9987 | to see how many times the problems occur, with the @code{set | |
9988 | complaints} command (@pxref{Messages/Warnings, ,Optional warnings and | |
9989 | messages}). | |
9990 | ||
9991 | The messages currently printed, and their meanings, include: | |
9992 | ||
9993 | @table @code | |
9994 | @item inner block not inside outer block in @var{symbol} | |
9995 | ||
9996 | The symbol information shows where symbol scopes begin and end | |
9997 | (such as at the start of a function or a block of statements). This | |
9998 | error indicates that an inner scope block is not fully contained | |
9999 | in its outer scope blocks. | |
10000 | ||
10001 | @value{GDBN} circumvents the problem by treating the inner block as if it had | |
10002 | the same scope as the outer block. In the error message, @var{symbol} | |
10003 | may be shown as ``@code{(don't know)}'' if the outer block is not a | |
10004 | function. | |
10005 | ||
10006 | @item block at @var{address} out of order | |
10007 | ||
10008 | The symbol information for symbol scope blocks should occur in | |
10009 | order of increasing addresses. This error indicates that it does not | |
10010 | do so. | |
10011 | ||
10012 | @value{GDBN} does not circumvent this problem, and has trouble | |
10013 | locating symbols in the source file whose symbols it is reading. (You | |
10014 | can often determine what source file is affected by specifying | |
10015 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and | |
10016 | messages}.) | |
10017 | ||
10018 | @item bad block start address patched | |
10019 | ||
10020 | The symbol information for a symbol scope block has a start address | |
10021 | smaller than the address of the preceding source line. This is known | |
10022 | to occur in the SunOS 4.1.1 (and earlier) C compiler. | |
10023 | ||
10024 | @value{GDBN} circumvents the problem by treating the symbol scope block as | |
10025 | starting on the previous source line. | |
10026 | ||
10027 | @item bad string table offset in symbol @var{n} | |
10028 | ||
10029 | @cindex foo | |
10030 | Symbol number @var{n} contains a pointer into the string table which is | |
10031 | larger than the size of the string table. | |
10032 | ||
10033 | @value{GDBN} circumvents the problem by considering the symbol to have the | |
10034 | name @code{foo}, which may cause other problems if many symbols end up | |
10035 | with this name. | |
10036 | ||
10037 | @item unknown symbol type @code{0x@var{nn}} | |
10038 | ||
7a292a7a SS |
10039 | The symbol information contains new data types that @value{GDBN} does |
10040 | not yet know how to read. @code{0x@var{nn}} is the symbol type of the | |
d4f3574e | 10041 | uncomprehended information, in hexadecimal. |
c906108c | 10042 | |
7a292a7a SS |
10043 | @value{GDBN} circumvents the error by ignoring this symbol information. |
10044 | This usually allows you to debug your program, though certain symbols | |
c906108c | 10045 | are not accessible. If you encounter such a problem and feel like |
7a292a7a SS |
10046 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint |
10047 | on @code{complain}, then go up to the function @code{read_dbx_symtab} | |
10048 | and examine @code{*bufp} to see the symbol. | |
c906108c SS |
10049 | |
10050 | @item stub type has NULL name | |
c906108c | 10051 | |
7a292a7a | 10052 | @value{GDBN} could not find the full definition for a struct or class. |
c906108c | 10053 | |
7a292a7a | 10054 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
b37052ae | 10055 | The symbol information for a C@t{++} member function is missing some |
7a292a7a SS |
10056 | information that recent versions of the compiler should have output for |
10057 | it. | |
c906108c SS |
10058 | |
10059 | @item info mismatch between compiler and debugger | |
10060 | ||
10061 | @value{GDBN} could not parse a type specification output by the compiler. | |
7a292a7a | 10062 | |
c906108c SS |
10063 | @end table |
10064 | ||
6d2ebf8b | 10065 | @node Targets |
c906108c | 10066 | @chapter Specifying a Debugging Target |
7a292a7a | 10067 | |
c906108c SS |
10068 | @cindex debugging target |
10069 | @kindex target | |
10070 | ||
10071 | A @dfn{target} is the execution environment occupied by your program. | |
53a5351d JM |
10072 | |
10073 | Often, @value{GDBN} runs in the same host environment as your program; | |
10074 | in that case, the debugging target is specified as a side effect when | |
10075 | you use the @code{file} or @code{core} commands. When you need more | |
c906108c SS |
10076 | flexibility---for example, running @value{GDBN} on a physically separate |
10077 | host, or controlling a standalone system over a serial port or a | |
53a5351d JM |
10078 | realtime system over a TCP/IP connection---you can use the @code{target} |
10079 | command to specify one of the target types configured for @value{GDBN} | |
10080 | (@pxref{Target Commands, ,Commands for managing targets}). | |
c906108c SS |
10081 | |
10082 | @menu | |
10083 | * Active Targets:: Active targets | |
10084 | * Target Commands:: Commands for managing targets | |
c906108c SS |
10085 | * Byte Order:: Choosing target byte order |
10086 | * Remote:: Remote debugging | |
96baa820 | 10087 | * KOD:: Kernel Object Display |
c906108c SS |
10088 | |
10089 | @end menu | |
10090 | ||
6d2ebf8b | 10091 | @node Active Targets |
c906108c | 10092 | @section Active targets |
7a292a7a | 10093 | |
c906108c SS |
10094 | @cindex stacking targets |
10095 | @cindex active targets | |
10096 | @cindex multiple targets | |
10097 | ||
c906108c | 10098 | There are three classes of targets: processes, core files, and |
7a292a7a SS |
10099 | executable files. @value{GDBN} can work concurrently on up to three |
10100 | active targets, one in each class. This allows you to (for example) | |
10101 | start a process and inspect its activity without abandoning your work on | |
10102 | a core file. | |
c906108c SS |
10103 | |
10104 | For example, if you execute @samp{gdb a.out}, then the executable file | |
10105 | @code{a.out} is the only active target. If you designate a core file as | |
10106 | well---presumably from a prior run that crashed and coredumped---then | |
10107 | @value{GDBN} has two active targets and uses them in tandem, looking | |
10108 | first in the corefile target, then in the executable file, to satisfy | |
10109 | requests for memory addresses. (Typically, these two classes of target | |
10110 | are complementary, since core files contain only a program's | |
10111 | read-write memory---variables and so on---plus machine status, while | |
10112 | executable files contain only the program text and initialized data.) | |
c906108c SS |
10113 | |
10114 | When you type @code{run}, your executable file becomes an active process | |
7a292a7a SS |
10115 | target as well. When a process target is active, all @value{GDBN} |
10116 | commands requesting memory addresses refer to that target; addresses in | |
10117 | an active core file or executable file target are obscured while the | |
10118 | process target is active. | |
c906108c | 10119 | |
7a292a7a SS |
10120 | Use the @code{core-file} and @code{exec-file} commands to select a new |
10121 | core file or executable target (@pxref{Files, ,Commands to specify | |
c906108c | 10122 | files}). To specify as a target a process that is already running, use |
7a292a7a SS |
10123 | the @code{attach} command (@pxref{Attach, ,Debugging an already-running |
10124 | process}). | |
c906108c | 10125 | |
6d2ebf8b | 10126 | @node Target Commands |
c906108c SS |
10127 | @section Commands for managing targets |
10128 | ||
10129 | @table @code | |
10130 | @item target @var{type} @var{parameters} | |
7a292a7a SS |
10131 | Connects the @value{GDBN} host environment to a target machine or |
10132 | process. A target is typically a protocol for talking to debugging | |
10133 | facilities. You use the argument @var{type} to specify the type or | |
10134 | protocol of the target machine. | |
c906108c SS |
10135 | |
10136 | Further @var{parameters} are interpreted by the target protocol, but | |
10137 | typically include things like device names or host names to connect | |
10138 | with, process numbers, and baud rates. | |
c906108c SS |
10139 | |
10140 | The @code{target} command does not repeat if you press @key{RET} again | |
10141 | after executing the command. | |
10142 | ||
10143 | @kindex help target | |
10144 | @item help target | |
10145 | Displays the names of all targets available. To display targets | |
10146 | currently selected, use either @code{info target} or @code{info files} | |
10147 | (@pxref{Files, ,Commands to specify files}). | |
10148 | ||
10149 | @item help target @var{name} | |
10150 | Describe a particular target, including any parameters necessary to | |
10151 | select it. | |
10152 | ||
10153 | @kindex set gnutarget | |
10154 | @item set gnutarget @var{args} | |
5d161b24 | 10155 | @value{GDBN} uses its own library BFD to read your files. @value{GDBN} |
c906108c | 10156 | knows whether it is reading an @dfn{executable}, |
5d161b24 DB |
10157 | a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format |
10158 | with the @code{set gnutarget} command. Unlike most @code{target} commands, | |
c906108c SS |
10159 | with @code{gnutarget} the @code{target} refers to a program, not a machine. |
10160 | ||
d4f3574e | 10161 | @quotation |
c906108c SS |
10162 | @emph{Warning:} To specify a file format with @code{set gnutarget}, |
10163 | you must know the actual BFD name. | |
d4f3574e | 10164 | @end quotation |
c906108c | 10165 | |
d4f3574e SS |
10166 | @noindent |
10167 | @xref{Files, , Commands to specify files}. | |
c906108c | 10168 | |
5d161b24 | 10169 | @kindex show gnutarget |
c906108c SS |
10170 | @item show gnutarget |
10171 | Use the @code{show gnutarget} command to display what file format | |
10172 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, | |
10173 | @value{GDBN} will determine the file format for each file automatically, | |
10174 | and @code{show gnutarget} displays @samp{The current BDF target is "auto"}. | |
10175 | @end table | |
10176 | ||
c906108c SS |
10177 | Here are some common targets (available, or not, depending on the GDB |
10178 | configuration): | |
c906108c SS |
10179 | |
10180 | @table @code | |
10181 | @kindex target exec | |
10182 | @item target exec @var{program} | |
10183 | An executable file. @samp{target exec @var{program}} is the same as | |
10184 | @samp{exec-file @var{program}}. | |
10185 | ||
c906108c SS |
10186 | @kindex target core |
10187 | @item target core @var{filename} | |
10188 | A core dump file. @samp{target core @var{filename}} is the same as | |
10189 | @samp{core-file @var{filename}}. | |
c906108c SS |
10190 | |
10191 | @kindex target remote | |
10192 | @item target remote @var{dev} | |
10193 | Remote serial target in GDB-specific protocol. The argument @var{dev} | |
10194 | specifies what serial device to use for the connection (e.g. | |
10195 | @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote} | |
d4f3574e | 10196 | supports the @code{load} command. This is only useful if you have |
c906108c SS |
10197 | some other way of getting the stub to the target system, and you can put |
10198 | it somewhere in memory where it won't get clobbered by the download. | |
10199 | ||
c906108c SS |
10200 | @kindex target sim |
10201 | @item target sim | |
2df3850c | 10202 | Builtin CPU simulator. @value{GDBN} includes simulators for most architectures. |
104c1213 | 10203 | In general, |
474c8240 | 10204 | @smallexample |
104c1213 JM |
10205 | target sim |
10206 | load | |
10207 | run | |
474c8240 | 10208 | @end smallexample |
d4f3574e | 10209 | @noindent |
104c1213 | 10210 | works; however, you cannot assume that a specific memory map, device |
d4f3574e | 10211 | drivers, or even basic I/O is available, although some simulators do |
104c1213 JM |
10212 | provide these. For info about any processor-specific simulator details, |
10213 | see the appropriate section in @ref{Embedded Processors, ,Embedded | |
10214 | Processors}. | |
10215 | ||
c906108c SS |
10216 | @end table |
10217 | ||
104c1213 | 10218 | Some configurations may include these targets as well: |
c906108c SS |
10219 | |
10220 | @table @code | |
10221 | ||
c906108c SS |
10222 | @kindex target nrom |
10223 | @item target nrom @var{dev} | |
10224 | NetROM ROM emulator. This target only supports downloading. | |
10225 | ||
c906108c SS |
10226 | @end table |
10227 | ||
5d161b24 | 10228 | Different targets are available on different configurations of @value{GDBN}; |
c906108c | 10229 | your configuration may have more or fewer targets. |
c906108c SS |
10230 | |
10231 | Many remote targets require you to download the executable's code | |
10232 | once you've successfully established a connection. | |
10233 | ||
10234 | @table @code | |
10235 | ||
10236 | @kindex load @var{filename} | |
10237 | @item load @var{filename} | |
c906108c SS |
10238 | Depending on what remote debugging facilities are configured into |
10239 | @value{GDBN}, the @code{load} command may be available. Where it exists, it | |
10240 | is meant to make @var{filename} (an executable) available for debugging | |
10241 | on the remote system---by downloading, or dynamic linking, for example. | |
10242 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like | |
10243 | the @code{add-symbol-file} command. | |
10244 | ||
10245 | If your @value{GDBN} does not have a @code{load} command, attempting to | |
10246 | execute it gets the error message ``@code{You can't do that when your | |
10247 | target is @dots{}}'' | |
c906108c SS |
10248 | |
10249 | The file is loaded at whatever address is specified in the executable. | |
10250 | For some object file formats, you can specify the load address when you | |
10251 | link the program; for other formats, like a.out, the object file format | |
10252 | specifies a fixed address. | |
10253 | @c FIXME! This would be a good place for an xref to the GNU linker doc. | |
10254 | ||
c906108c SS |
10255 | @code{load} does not repeat if you press @key{RET} again after using it. |
10256 | @end table | |
10257 | ||
6d2ebf8b | 10258 | @node Byte Order |
c906108c | 10259 | @section Choosing target byte order |
7a292a7a | 10260 | |
c906108c SS |
10261 | @cindex choosing target byte order |
10262 | @cindex target byte order | |
c906108c SS |
10263 | |
10264 | Some types of processors, such as the MIPS, PowerPC, and Hitachi SH, | |
10265 | offer the ability to run either big-endian or little-endian byte | |
10266 | orders. Usually the executable or symbol will include a bit to | |
10267 | designate the endian-ness, and you will not need to worry about | |
10268 | which to use. However, you may still find it useful to adjust | |
d4f3574e | 10269 | @value{GDBN}'s idea of processor endian-ness manually. |
c906108c SS |
10270 | |
10271 | @table @code | |
10272 | @kindex set endian big | |
10273 | @item set endian big | |
10274 | Instruct @value{GDBN} to assume the target is big-endian. | |
10275 | ||
10276 | @kindex set endian little | |
10277 | @item set endian little | |
10278 | Instruct @value{GDBN} to assume the target is little-endian. | |
10279 | ||
10280 | @kindex set endian auto | |
10281 | @item set endian auto | |
10282 | Instruct @value{GDBN} to use the byte order associated with the | |
10283 | executable. | |
10284 | ||
10285 | @item show endian | |
10286 | Display @value{GDBN}'s current idea of the target byte order. | |
10287 | ||
10288 | @end table | |
10289 | ||
10290 | Note that these commands merely adjust interpretation of symbolic | |
10291 | data on the host, and that they have absolutely no effect on the | |
10292 | target system. | |
10293 | ||
6d2ebf8b | 10294 | @node Remote |
c906108c SS |
10295 | @section Remote debugging |
10296 | @cindex remote debugging | |
10297 | ||
10298 | If you are trying to debug a program running on a machine that cannot run | |
5d161b24 DB |
10299 | @value{GDBN} in the usual way, it is often useful to use remote debugging. |
10300 | For example, you might use remote debugging on an operating system kernel, | |
c906108c SS |
10301 | or on a small system which does not have a general purpose operating system |
10302 | powerful enough to run a full-featured debugger. | |
10303 | ||
10304 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces | |
10305 | to make this work with particular debugging targets. In addition, | |
5d161b24 | 10306 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, |
c906108c SS |
10307 | but not specific to any particular target system) which you can use if you |
10308 | write the remote stubs---the code that runs on the remote system to | |
10309 | communicate with @value{GDBN}. | |
10310 | ||
10311 | Other remote targets may be available in your | |
10312 | configuration of @value{GDBN}; use @code{help target} to list them. | |
c906108c | 10313 | |
6f05cf9f AC |
10314 | @node KOD |
10315 | @section Kernel Object Display | |
10316 | ||
10317 | @cindex kernel object display | |
10318 | @cindex kernel object | |
10319 | @cindex KOD | |
10320 | ||
10321 | Some targets support kernel object display. Using this facility, | |
10322 | @value{GDBN} communicates specially with the underlying operating system | |
10323 | and can display information about operating system-level objects such as | |
10324 | mutexes and other synchronization objects. Exactly which objects can be | |
10325 | displayed is determined on a per-OS basis. | |
10326 | ||
10327 | Use the @code{set os} command to set the operating system. This tells | |
10328 | @value{GDBN} which kernel object display module to initialize: | |
10329 | ||
474c8240 | 10330 | @smallexample |
6f05cf9f | 10331 | (@value{GDBP}) set os cisco |
474c8240 | 10332 | @end smallexample |
6f05cf9f AC |
10333 | |
10334 | If @code{set os} succeeds, @value{GDBN} will display some information | |
10335 | about the operating system, and will create a new @code{info} command | |
10336 | which can be used to query the target. The @code{info} command is named | |
10337 | after the operating system: | |
c906108c | 10338 | |
474c8240 | 10339 | @smallexample |
6f05cf9f AC |
10340 | (@value{GDBP}) info cisco |
10341 | List of Cisco Kernel Objects | |
10342 | Object Description | |
10343 | any Any and all objects | |
474c8240 | 10344 | @end smallexample |
6f05cf9f AC |
10345 | |
10346 | Further subcommands can be used to query about particular objects known | |
10347 | by the kernel. | |
10348 | ||
10349 | There is currently no way to determine whether a given operating system | |
10350 | is supported other than to try it. | |
10351 | ||
10352 | ||
10353 | @node Remote Debugging | |
10354 | @chapter Debugging remote programs | |
10355 | ||
6b2f586d AC |
10356 | @menu |
10357 | * Server:: Using the gdbserver program | |
10358 | * NetWare:: Using the gdbserve.nlm program | |
501eef12 | 10359 | * Remote configuration:: Remote configuration |
6b2f586d | 10360 | * remote stub:: Implementing a remote stub |
6b2f586d AC |
10361 | @end menu |
10362 | ||
6f05cf9f AC |
10363 | @node Server |
10364 | @section Using the @code{gdbserver} program | |
10365 | ||
10366 | @kindex gdbserver | |
10367 | @cindex remote connection without stubs | |
10368 | @code{gdbserver} is a control program for Unix-like systems, which | |
10369 | allows you to connect your program with a remote @value{GDBN} via | |
10370 | @code{target remote}---but without linking in the usual debugging stub. | |
10371 | ||
10372 | @code{gdbserver} is not a complete replacement for the debugging stubs, | |
10373 | because it requires essentially the same operating-system facilities | |
10374 | that @value{GDBN} itself does. In fact, a system that can run | |
10375 | @code{gdbserver} to connect to a remote @value{GDBN} could also run | |
10376 | @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, | |
10377 | because it is a much smaller program than @value{GDBN} itself. It is | |
10378 | also easier to port than all of @value{GDBN}, so you may be able to get | |
10379 | started more quickly on a new system by using @code{gdbserver}. | |
10380 | Finally, if you develop code for real-time systems, you may find that | |
10381 | the tradeoffs involved in real-time operation make it more convenient to | |
10382 | do as much development work as possible on another system, for example | |
10383 | by cross-compiling. You can use @code{gdbserver} to make a similar | |
10384 | choice for debugging. | |
10385 | ||
10386 | @value{GDBN} and @code{gdbserver} communicate via either a serial line | |
10387 | or a TCP connection, using the standard @value{GDBN} remote serial | |
10388 | protocol. | |
10389 | ||
10390 | @table @emph | |
10391 | @item On the target machine, | |
10392 | you need to have a copy of the program you want to debug. | |
10393 | @code{gdbserver} does not need your program's symbol table, so you can | |
10394 | strip the program if necessary to save space. @value{GDBN} on the host | |
10395 | system does all the symbol handling. | |
10396 | ||
10397 | To use the server, you must tell it how to communicate with @value{GDBN}; | |
56460a61 | 10398 | the name of your program; and the arguments for your program. The usual |
6f05cf9f AC |
10399 | syntax is: |
10400 | ||
10401 | @smallexample | |
10402 | target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] | |
10403 | @end smallexample | |
10404 | ||
10405 | @var{comm} is either a device name (to use a serial line) or a TCP | |
10406 | hostname and portnumber. For example, to debug Emacs with the argument | |
10407 | @samp{foo.txt} and communicate with @value{GDBN} over the serial port | |
10408 | @file{/dev/com1}: | |
10409 | ||
10410 | @smallexample | |
10411 | target> gdbserver /dev/com1 emacs foo.txt | |
10412 | @end smallexample | |
10413 | ||
10414 | @code{gdbserver} waits passively for the host @value{GDBN} to communicate | |
10415 | with it. | |
10416 | ||
10417 | To use a TCP connection instead of a serial line: | |
10418 | ||
10419 | @smallexample | |
10420 | target> gdbserver host:2345 emacs foo.txt | |
10421 | @end smallexample | |
10422 | ||
10423 | The only difference from the previous example is the first argument, | |
10424 | specifying that you are communicating with the host @value{GDBN} via | |
10425 | TCP. The @samp{host:2345} argument means that @code{gdbserver} is to | |
10426 | expect a TCP connection from machine @samp{host} to local TCP port 2345. | |
10427 | (Currently, the @samp{host} part is ignored.) You can choose any number | |
10428 | you want for the port number as long as it does not conflict with any | |
10429 | TCP ports already in use on the target system (for example, @code{23} is | |
10430 | reserved for @code{telnet}).@footnote{If you choose a port number that | |
10431 | conflicts with another service, @code{gdbserver} prints an error message | |
10432 | and exits.} You must use the same port number with the host @value{GDBN} | |
10433 | @code{target remote} command. | |
10434 | ||
56460a61 DJ |
10435 | On some targets, @code{gdbserver} can also attach to running programs. |
10436 | This is accomplished via the @code{--attach} argument. The syntax is: | |
10437 | ||
10438 | @smallexample | |
10439 | target> gdbserver @var{comm} --attach @var{pid} | |
10440 | @end smallexample | |
10441 | ||
10442 | @var{pid} is the process ID of a currently running process. It isn't necessary | |
10443 | to point @code{gdbserver} at a binary for the running process. | |
10444 | ||
6f05cf9f AC |
10445 | @item On the @value{GDBN} host machine, |
10446 | you need an unstripped copy of your program, since @value{GDBN} needs | |
10447 | symbols and debugging information. Start up @value{GDBN} as usual, | |
10448 | using the name of the local copy of your program as the first argument. | |
10449 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
10450 | running at anything other than 9600@dmn{bps}.) After that, use @code{target | |
10451 | remote} to establish communications with @code{gdbserver}. Its argument | |
10452 | is either a device name (usually a serial device, like | |
10453 | @file{/dev/ttyb}), or a TCP port descriptor in the form | |
10454 | @code{@var{host}:@var{PORT}}. For example: | |
10455 | ||
10456 | @smallexample | |
10457 | (@value{GDBP}) target remote /dev/ttyb | |
10458 | @end smallexample | |
10459 | ||
10460 | @noindent | |
10461 | communicates with the server via serial line @file{/dev/ttyb}, and | |
10462 | ||
10463 | @smallexample | |
10464 | (@value{GDBP}) target remote the-target:2345 | |
10465 | @end smallexample | |
10466 | ||
10467 | @noindent | |
10468 | communicates via a TCP connection to port 2345 on host @w{@file{the-target}}. | |
10469 | For TCP connections, you must start up @code{gdbserver} prior to using | |
10470 | the @code{target remote} command. Otherwise you may get an error whose | |
10471 | text depends on the host system, but which usually looks something like | |
10472 | @samp{Connection refused}. | |
10473 | @end table | |
10474 | ||
10475 | @node NetWare | |
10476 | @section Using the @code{gdbserve.nlm} program | |
10477 | ||
10478 | @kindex gdbserve.nlm | |
10479 | @code{gdbserve.nlm} is a control program for NetWare systems, which | |
10480 | allows you to connect your program with a remote @value{GDBN} via | |
10481 | @code{target remote}. | |
10482 | ||
10483 | @value{GDBN} and @code{gdbserve.nlm} communicate via a serial line, | |
10484 | using the standard @value{GDBN} remote serial protocol. | |
10485 | ||
10486 | @table @emph | |
10487 | @item On the target machine, | |
10488 | you need to have a copy of the program you want to debug. | |
10489 | @code{gdbserve.nlm} does not need your program's symbol table, so you | |
10490 | can strip the program if necessary to save space. @value{GDBN} on the | |
10491 | host system does all the symbol handling. | |
10492 | ||
10493 | To use the server, you must tell it how to communicate with | |
10494 | @value{GDBN}; the name of your program; and the arguments for your | |
10495 | program. The syntax is: | |
10496 | ||
10497 | @smallexample | |
10498 | load gdbserve [ BOARD=@var{board} ] [ PORT=@var{port} ] | |
10499 | [ BAUD=@var{baud} ] @var{program} [ @var{args} @dots{} ] | |
10500 | @end smallexample | |
10501 | ||
10502 | @var{board} and @var{port} specify the serial line; @var{baud} specifies | |
10503 | the baud rate used by the connection. @var{port} and @var{node} default | |
10504 | to 0, @var{baud} defaults to 9600@dmn{bps}. | |
10505 | ||
10506 | For example, to debug Emacs with the argument @samp{foo.txt}and | |
10507 | communicate with @value{GDBN} over serial port number 2 or board 1 | |
10508 | using a 19200@dmn{bps} connection: | |
10509 | ||
10510 | @smallexample | |
10511 | load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt | |
10512 | @end smallexample | |
10513 | ||
10514 | @item On the @value{GDBN} host machine, | |
10515 | you need an unstripped copy of your program, since @value{GDBN} needs | |
10516 | symbols and debugging information. Start up @value{GDBN} as usual, | |
10517 | using the name of the local copy of your program as the first argument. | |
10518 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
10519 | running at anything other than 9600@dmn{bps}. After that, use @code{target | |
10520 | remote} to establish communications with @code{gdbserve.nlm}. Its | |
10521 | argument is a device name (usually a serial device, like | |
10522 | @file{/dev/ttyb}). For example: | |
10523 | ||
10524 | @smallexample | |
10525 | (@value{GDBP}) target remote /dev/ttyb | |
10526 | @end smallexample | |
10527 | ||
10528 | @noindent | |
10529 | communications with the server via serial line @file{/dev/ttyb}. | |
10530 | @end table | |
10531 | ||
501eef12 AC |
10532 | @node Remote configuration |
10533 | @section Remote configuration | |
10534 | ||
10535 | The following configuration options are available when debugging remote | |
10536 | programs: | |
10537 | ||
10538 | @table @code | |
10539 | @kindex set remote hardware-watchpoint-limit | |
10540 | @kindex set remote hardware-breakpoint-limit | |
10541 | @anchor{set remote hardware-watchpoint-limit} | |
10542 | @anchor{set remote hardware-breakpoint-limit} | |
10543 | @item set remote hardware-watchpoint-limit @var{limit} | |
10544 | @itemx set remote hardware-breakpoint-limit @var{limit} | |
10545 | Restrict @value{GDBN} to using @var{limit} remote hardware breakpoint or | |
10546 | watchpoints. A limit of -1, the default, is treated as unlimited. | |
10547 | @end table | |
10548 | ||
6f05cf9f AC |
10549 | @node remote stub |
10550 | @section Implementing a remote stub | |
7a292a7a | 10551 | |
8e04817f AC |
10552 | @cindex debugging stub, example |
10553 | @cindex remote stub, example | |
10554 | @cindex stub example, remote debugging | |
10555 | The stub files provided with @value{GDBN} implement the target side of the | |
10556 | communication protocol, and the @value{GDBN} side is implemented in the | |
10557 | @value{GDBN} source file @file{remote.c}. Normally, you can simply allow | |
10558 | these subroutines to communicate, and ignore the details. (If you're | |
10559 | implementing your own stub file, you can still ignore the details: start | |
10560 | with one of the existing stub files. @file{sparc-stub.c} is the best | |
10561 | organized, and therefore the easiest to read.) | |
10562 | ||
104c1213 JM |
10563 | @cindex remote serial debugging, overview |
10564 | To debug a program running on another machine (the debugging | |
10565 | @dfn{target} machine), you must first arrange for all the usual | |
10566 | prerequisites for the program to run by itself. For example, for a C | |
10567 | program, you need: | |
c906108c | 10568 | |
104c1213 JM |
10569 | @enumerate |
10570 | @item | |
10571 | A startup routine to set up the C runtime environment; these usually | |
10572 | have a name like @file{crt0}. The startup routine may be supplied by | |
10573 | your hardware supplier, or you may have to write your own. | |
96baa820 | 10574 | |
5d161b24 | 10575 | @item |
d4f3574e | 10576 | A C subroutine library to support your program's |
104c1213 | 10577 | subroutine calls, notably managing input and output. |
96baa820 | 10578 | |
104c1213 JM |
10579 | @item |
10580 | A way of getting your program to the other machine---for example, a | |
10581 | download program. These are often supplied by the hardware | |
10582 | manufacturer, but you may have to write your own from hardware | |
10583 | documentation. | |
10584 | @end enumerate | |
96baa820 | 10585 | |
104c1213 JM |
10586 | The next step is to arrange for your program to use a serial port to |
10587 | communicate with the machine where @value{GDBN} is running (the @dfn{host} | |
10588 | machine). In general terms, the scheme looks like this: | |
96baa820 | 10589 | |
104c1213 JM |
10590 | @table @emph |
10591 | @item On the host, | |
10592 | @value{GDBN} already understands how to use this protocol; when everything | |
10593 | else is set up, you can simply use the @samp{target remote} command | |
10594 | (@pxref{Targets,,Specifying a Debugging Target}). | |
10595 | ||
10596 | @item On the target, | |
10597 | you must link with your program a few special-purpose subroutines that | |
10598 | implement the @value{GDBN} remote serial protocol. The file containing these | |
10599 | subroutines is called a @dfn{debugging stub}. | |
10600 | ||
10601 | On certain remote targets, you can use an auxiliary program | |
10602 | @code{gdbserver} instead of linking a stub into your program. | |
10603 | @xref{Server,,Using the @code{gdbserver} program}, for details. | |
10604 | @end table | |
96baa820 | 10605 | |
104c1213 JM |
10606 | The debugging stub is specific to the architecture of the remote |
10607 | machine; for example, use @file{sparc-stub.c} to debug programs on | |
10608 | @sc{sparc} boards. | |
96baa820 | 10609 | |
104c1213 JM |
10610 | @cindex remote serial stub list |
10611 | These working remote stubs are distributed with @value{GDBN}: | |
96baa820 | 10612 | |
104c1213 JM |
10613 | @table @code |
10614 | ||
10615 | @item i386-stub.c | |
41afff9a | 10616 | @cindex @file{i386-stub.c} |
104c1213 JM |
10617 | @cindex Intel |
10618 | @cindex i386 | |
10619 | For Intel 386 and compatible architectures. | |
10620 | ||
10621 | @item m68k-stub.c | |
41afff9a | 10622 | @cindex @file{m68k-stub.c} |
104c1213 JM |
10623 | @cindex Motorola 680x0 |
10624 | @cindex m680x0 | |
10625 | For Motorola 680x0 architectures. | |
10626 | ||
10627 | @item sh-stub.c | |
41afff9a | 10628 | @cindex @file{sh-stub.c} |
104c1213 JM |
10629 | @cindex Hitachi |
10630 | @cindex SH | |
10631 | For Hitachi SH architectures. | |
10632 | ||
10633 | @item sparc-stub.c | |
41afff9a | 10634 | @cindex @file{sparc-stub.c} |
104c1213 JM |
10635 | @cindex Sparc |
10636 | For @sc{sparc} architectures. | |
10637 | ||
10638 | @item sparcl-stub.c | |
41afff9a | 10639 | @cindex @file{sparcl-stub.c} |
104c1213 JM |
10640 | @cindex Fujitsu |
10641 | @cindex SparcLite | |
10642 | For Fujitsu @sc{sparclite} architectures. | |
10643 | ||
10644 | @end table | |
10645 | ||
10646 | The @file{README} file in the @value{GDBN} distribution may list other | |
10647 | recently added stubs. | |
10648 | ||
10649 | @menu | |
10650 | * Stub Contents:: What the stub can do for you | |
10651 | * Bootstrapping:: What you must do for the stub | |
10652 | * Debug Session:: Putting it all together | |
104c1213 JM |
10653 | @end menu |
10654 | ||
6d2ebf8b | 10655 | @node Stub Contents |
6f05cf9f | 10656 | @subsection What the stub can do for you |
104c1213 JM |
10657 | |
10658 | @cindex remote serial stub | |
10659 | The debugging stub for your architecture supplies these three | |
10660 | subroutines: | |
10661 | ||
10662 | @table @code | |
10663 | @item set_debug_traps | |
10664 | @kindex set_debug_traps | |
10665 | @cindex remote serial stub, initialization | |
10666 | This routine arranges for @code{handle_exception} to run when your | |
10667 | program stops. You must call this subroutine explicitly near the | |
10668 | beginning of your program. | |
10669 | ||
10670 | @item handle_exception | |
10671 | @kindex handle_exception | |
10672 | @cindex remote serial stub, main routine | |
10673 | This is the central workhorse, but your program never calls it | |
10674 | explicitly---the setup code arranges for @code{handle_exception} to | |
10675 | run when a trap is triggered. | |
10676 | ||
10677 | @code{handle_exception} takes control when your program stops during | |
10678 | execution (for example, on a breakpoint), and mediates communications | |
10679 | with @value{GDBN} on the host machine. This is where the communications | |
10680 | protocol is implemented; @code{handle_exception} acts as the @value{GDBN} | |
d4f3574e | 10681 | representative on the target machine. It begins by sending summary |
104c1213 JM |
10682 | information on the state of your program, then continues to execute, |
10683 | retrieving and transmitting any information @value{GDBN} needs, until you | |
10684 | execute a @value{GDBN} command that makes your program resume; at that point, | |
10685 | @code{handle_exception} returns control to your own code on the target | |
5d161b24 | 10686 | machine. |
104c1213 JM |
10687 | |
10688 | @item breakpoint | |
10689 | @cindex @code{breakpoint} subroutine, remote | |
10690 | Use this auxiliary subroutine to make your program contain a | |
10691 | breakpoint. Depending on the particular situation, this may be the only | |
10692 | way for @value{GDBN} to get control. For instance, if your target | |
10693 | machine has some sort of interrupt button, you won't need to call this; | |
10694 | pressing the interrupt button transfers control to | |
10695 | @code{handle_exception}---in effect, to @value{GDBN}. On some machines, | |
10696 | simply receiving characters on the serial port may also trigger a trap; | |
10697 | again, in that situation, you don't need to call @code{breakpoint} from | |
10698 | your own program---simply running @samp{target remote} from the host | |
5d161b24 | 10699 | @value{GDBN} session gets control. |
104c1213 JM |
10700 | |
10701 | Call @code{breakpoint} if none of these is true, or if you simply want | |
10702 | to make certain your program stops at a predetermined point for the | |
10703 | start of your debugging session. | |
10704 | @end table | |
10705 | ||
6d2ebf8b | 10706 | @node Bootstrapping |
6f05cf9f | 10707 | @subsection What you must do for the stub |
104c1213 JM |
10708 | |
10709 | @cindex remote stub, support routines | |
10710 | The debugging stubs that come with @value{GDBN} are set up for a particular | |
10711 | chip architecture, but they have no information about the rest of your | |
10712 | debugging target machine. | |
10713 | ||
10714 | First of all you need to tell the stub how to communicate with the | |
10715 | serial port. | |
10716 | ||
10717 | @table @code | |
10718 | @item int getDebugChar() | |
10719 | @kindex getDebugChar | |
10720 | Write this subroutine to read a single character from the serial port. | |
10721 | It may be identical to @code{getchar} for your target system; a | |
10722 | different name is used to allow you to distinguish the two if you wish. | |
10723 | ||
10724 | @item void putDebugChar(int) | |
10725 | @kindex putDebugChar | |
10726 | Write this subroutine to write a single character to the serial port. | |
5d161b24 | 10727 | It may be identical to @code{putchar} for your target system; a |
104c1213 JM |
10728 | different name is used to allow you to distinguish the two if you wish. |
10729 | @end table | |
10730 | ||
10731 | @cindex control C, and remote debugging | |
10732 | @cindex interrupting remote targets | |
10733 | If you want @value{GDBN} to be able to stop your program while it is | |
10734 | running, you need to use an interrupt-driven serial driver, and arrange | |
10735 | for it to stop when it receives a @code{^C} (@samp{\003}, the control-C | |
10736 | character). That is the character which @value{GDBN} uses to tell the | |
10737 | remote system to stop. | |
10738 | ||
10739 | Getting the debugging target to return the proper status to @value{GDBN} | |
10740 | probably requires changes to the standard stub; one quick and dirty way | |
10741 | is to just execute a breakpoint instruction (the ``dirty'' part is that | |
10742 | @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). | |
10743 | ||
10744 | Other routines you need to supply are: | |
10745 | ||
10746 | @table @code | |
10747 | @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) | |
10748 | @kindex exceptionHandler | |
10749 | Write this function to install @var{exception_address} in the exception | |
10750 | handling tables. You need to do this because the stub does not have any | |
10751 | way of knowing what the exception handling tables on your target system | |
10752 | are like (for example, the processor's table might be in @sc{rom}, | |
10753 | containing entries which point to a table in @sc{ram}). | |
10754 | @var{exception_number} is the exception number which should be changed; | |
10755 | its meaning is architecture-dependent (for example, different numbers | |
10756 | might represent divide by zero, misaligned access, etc). When this | |
10757 | exception occurs, control should be transferred directly to | |
10758 | @var{exception_address}, and the processor state (stack, registers, | |
10759 | and so on) should be just as it is when a processor exception occurs. So if | |
10760 | you want to use a jump instruction to reach @var{exception_address}, it | |
10761 | should be a simple jump, not a jump to subroutine. | |
10762 | ||
10763 | For the 386, @var{exception_address} should be installed as an interrupt | |
10764 | gate so that interrupts are masked while the handler runs. The gate | |
10765 | should be at privilege level 0 (the most privileged level). The | |
10766 | @sc{sparc} and 68k stubs are able to mask interrupts themselves without | |
10767 | help from @code{exceptionHandler}. | |
10768 | ||
10769 | @item void flush_i_cache() | |
10770 | @kindex flush_i_cache | |
d4f3574e | 10771 | On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the |
104c1213 JM |
10772 | instruction cache, if any, on your target machine. If there is no |
10773 | instruction cache, this subroutine may be a no-op. | |
10774 | ||
10775 | On target machines that have instruction caches, @value{GDBN} requires this | |
10776 | function to make certain that the state of your program is stable. | |
10777 | @end table | |
10778 | ||
10779 | @noindent | |
10780 | You must also make sure this library routine is available: | |
10781 | ||
10782 | @table @code | |
10783 | @item void *memset(void *, int, int) | |
10784 | @kindex memset | |
10785 | This is the standard library function @code{memset} that sets an area of | |
10786 | memory to a known value. If you have one of the free versions of | |
10787 | @code{libc.a}, @code{memset} can be found there; otherwise, you must | |
10788 | either obtain it from your hardware manufacturer, or write your own. | |
10789 | @end table | |
10790 | ||
10791 | If you do not use the GNU C compiler, you may need other standard | |
10792 | library subroutines as well; this varies from one stub to another, | |
10793 | but in general the stubs are likely to use any of the common library | |
d4f3574e | 10794 | subroutines which @code{@value{GCC}} generates as inline code. |
104c1213 JM |
10795 | |
10796 | ||
6d2ebf8b | 10797 | @node Debug Session |
6f05cf9f | 10798 | @subsection Putting it all together |
104c1213 JM |
10799 | |
10800 | @cindex remote serial debugging summary | |
10801 | In summary, when your program is ready to debug, you must follow these | |
10802 | steps. | |
10803 | ||
10804 | @enumerate | |
10805 | @item | |
6d2ebf8b | 10806 | Make sure you have defined the supporting low-level routines |
104c1213 JM |
10807 | (@pxref{Bootstrapping,,What you must do for the stub}): |
10808 | @display | |
10809 | @code{getDebugChar}, @code{putDebugChar}, | |
10810 | @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. | |
10811 | @end display | |
10812 | ||
10813 | @item | |
10814 | Insert these lines near the top of your program: | |
10815 | ||
474c8240 | 10816 | @smallexample |
104c1213 JM |
10817 | set_debug_traps(); |
10818 | breakpoint(); | |
474c8240 | 10819 | @end smallexample |
104c1213 JM |
10820 | |
10821 | @item | |
10822 | For the 680x0 stub only, you need to provide a variable called | |
10823 | @code{exceptionHook}. Normally you just use: | |
10824 | ||
474c8240 | 10825 | @smallexample |
104c1213 | 10826 | void (*exceptionHook)() = 0; |
474c8240 | 10827 | @end smallexample |
104c1213 | 10828 | |
d4f3574e | 10829 | @noindent |
104c1213 | 10830 | but if before calling @code{set_debug_traps}, you set it to point to a |
598ca718 | 10831 | function in your program, that function is called when |
104c1213 JM |
10832 | @code{@value{GDBN}} continues after stopping on a trap (for example, bus |
10833 | error). The function indicated by @code{exceptionHook} is called with | |
10834 | one parameter: an @code{int} which is the exception number. | |
10835 | ||
10836 | @item | |
10837 | Compile and link together: your program, the @value{GDBN} debugging stub for | |
10838 | your target architecture, and the supporting subroutines. | |
10839 | ||
10840 | @item | |
10841 | Make sure you have a serial connection between your target machine and | |
10842 | the @value{GDBN} host, and identify the serial port on the host. | |
10843 | ||
10844 | @item | |
10845 | @c The "remote" target now provides a `load' command, so we should | |
10846 | @c document that. FIXME. | |
10847 | Download your program to your target machine (or get it there by | |
10848 | whatever means the manufacturer provides), and start it. | |
10849 | ||
10850 | @item | |
10851 | To start remote debugging, run @value{GDBN} on the host machine, and specify | |
10852 | as an executable file the program that is running in the remote machine. | |
10853 | This tells @value{GDBN} how to find your program's symbols and the contents | |
10854 | of its pure text. | |
10855 | ||
d4f3574e | 10856 | @item |
104c1213 | 10857 | @cindex serial line, @code{target remote} |
d4f3574e | 10858 | Establish communication using the @code{target remote} command. |
104c1213 JM |
10859 | Its argument specifies how to communicate with the target |
10860 | machine---either via a devicename attached to a direct serial line, or a | |
9db8d71f | 10861 | TCP or UDP port (usually to a terminal server which in turn has a serial line |
104c1213 JM |
10862 | to the target). For example, to use a serial line connected to the |
10863 | device named @file{/dev/ttyb}: | |
10864 | ||
474c8240 | 10865 | @smallexample |
104c1213 | 10866 | target remote /dev/ttyb |
474c8240 | 10867 | @end smallexample |
104c1213 JM |
10868 | |
10869 | @cindex TCP port, @code{target remote} | |
10870 | To use a TCP connection, use an argument of the form | |
9db8d71f DJ |
10871 | @code{@var{host}:@var{port}} or @code{tcp:@var{host}:@var{port}}. |
10872 | For example, to connect to port 2828 on a | |
104c1213 JM |
10873 | terminal server named @code{manyfarms}: |
10874 | ||
474c8240 | 10875 | @smallexample |
104c1213 | 10876 | target remote manyfarms:2828 |
474c8240 | 10877 | @end smallexample |
a2bea4c3 CV |
10878 | |
10879 | If your remote target is actually running on the same machine as | |
10880 | your debugger session (e.g.@: a simulator of your target running on | |
10881 | the same host), you can omit the hostname. For example, to connect | |
10882 | to port 1234 on your local machine: | |
10883 | ||
474c8240 | 10884 | @smallexample |
a2bea4c3 | 10885 | target remote :1234 |
474c8240 | 10886 | @end smallexample |
a2bea4c3 CV |
10887 | @noindent |
10888 | ||
10889 | Note that the colon is still required here. | |
9db8d71f DJ |
10890 | |
10891 | @cindex UDP port, @code{target remote} | |
10892 | To use a UDP connection, use an argument of the form | |
10893 | @code{udp:@var{host}:@var{port}}. For example, to connect to UDP port 2828 | |
10894 | on a terminal server named @code{manyfarms}: | |
10895 | ||
10896 | @smallexample | |
10897 | target remote udp:manyfarms:2828 | |
10898 | @end smallexample | |
10899 | ||
10900 | When using a UDP connection for remote debugging, you should keep in mind | |
10901 | that the `U' stands for ``Unreliable''. UDP can silently drop packets on | |
10902 | busy or unreliable networks, which will cause havoc with your debugging | |
10903 | session. | |
10904 | ||
104c1213 JM |
10905 | @end enumerate |
10906 | ||
10907 | Now you can use all the usual commands to examine and change data and to | |
10908 | step and continue the remote program. | |
10909 | ||
10910 | To resume the remote program and stop debugging it, use the @code{detach} | |
10911 | command. | |
10912 | ||
10913 | @cindex interrupting remote programs | |
10914 | @cindex remote programs, interrupting | |
10915 | Whenever @value{GDBN} is waiting for the remote program, if you type the | |
10916 | interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the | |
10917 | program. This may or may not succeed, depending in part on the hardware | |
10918 | and the serial drivers the remote system uses. If you type the | |
10919 | interrupt character once again, @value{GDBN} displays this prompt: | |
10920 | ||
474c8240 | 10921 | @smallexample |
104c1213 JM |
10922 | Interrupted while waiting for the program. |
10923 | Give up (and stop debugging it)? (y or n) | |
474c8240 | 10924 | @end smallexample |
104c1213 JM |
10925 | |
10926 | If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. | |
10927 | (If you decide you want to try again later, you can use @samp{target | |
10928 | remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} | |
10929 | goes back to waiting. | |
10930 | ||
104c1213 | 10931 | |
8e04817f AC |
10932 | @node Configurations |
10933 | @chapter Configuration-Specific Information | |
104c1213 | 10934 | |
8e04817f AC |
10935 | While nearly all @value{GDBN} commands are available for all native and |
10936 | cross versions of the debugger, there are some exceptions. This chapter | |
10937 | describes things that are only available in certain configurations. | |
104c1213 | 10938 | |
8e04817f AC |
10939 | There are three major categories of configurations: native |
10940 | configurations, where the host and target are the same, embedded | |
10941 | operating system configurations, which are usually the same for several | |
10942 | different processor architectures, and bare embedded processors, which | |
10943 | are quite different from each other. | |
104c1213 | 10944 | |
8e04817f AC |
10945 | @menu |
10946 | * Native:: | |
10947 | * Embedded OS:: | |
10948 | * Embedded Processors:: | |
10949 | * Architectures:: | |
10950 | @end menu | |
104c1213 | 10951 | |
8e04817f AC |
10952 | @node Native |
10953 | @section Native | |
104c1213 | 10954 | |
8e04817f AC |
10955 | This section describes details specific to particular native |
10956 | configurations. | |
6cf7e474 | 10957 | |
8e04817f AC |
10958 | @menu |
10959 | * HP-UX:: HP-UX | |
10960 | * SVR4 Process Information:: SVR4 process information | |
10961 | * DJGPP Native:: Features specific to the DJGPP port | |
78c47bea | 10962 | * Cygwin Native:: Features specific to the Cygwin port |
8e04817f | 10963 | @end menu |
6cf7e474 | 10964 | |
8e04817f AC |
10965 | @node HP-UX |
10966 | @subsection HP-UX | |
104c1213 | 10967 | |
8e04817f AC |
10968 | On HP-UX systems, if you refer to a function or variable name that |
10969 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
10970 | name first, before it searches for a convenience variable. | |
104c1213 | 10971 | |
8e04817f AC |
10972 | @node SVR4 Process Information |
10973 | @subsection SVR4 process information | |
104c1213 | 10974 | |
8e04817f AC |
10975 | @kindex /proc |
10976 | @cindex process image | |
104c1213 | 10977 | |
8e04817f AC |
10978 | Many versions of SVR4 provide a facility called @samp{/proc} that can be |
10979 | used to examine the image of a running process using file-system | |
10980 | subroutines. If @value{GDBN} is configured for an operating system with | |
10981 | this facility, the command @code{info proc} is available to report on | |
10982 | several kinds of information about the process running your program. | |
10983 | @code{info proc} works only on SVR4 systems that include the | |
10984 | @code{procfs} code. This includes OSF/1 (Digital Unix), Solaris, Irix, | |
1104b9e7 | 10985 | and Unixware, but not HP-UX or @sc{gnu}/Linux, for example. |
104c1213 | 10986 | |
8e04817f AC |
10987 | @table @code |
10988 | @kindex info proc | |
10989 | @item info proc | |
10990 | Summarize available information about the process. | |
6cf7e474 | 10991 | |
8e04817f AC |
10992 | @kindex info proc mappings |
10993 | @item info proc mappings | |
10994 | Report on the address ranges accessible in the program, with information | |
10995 | on whether your program may read, write, or execute each range. | |
10996 | @ignore | |
10997 | @comment These sub-options of 'info proc' were not included when | |
10998 | @comment procfs.c was re-written. Keep their descriptions around | |
10999 | @comment against the day when someone finds the time to put them back in. | |
11000 | @kindex info proc times | |
11001 | @item info proc times | |
11002 | Starting time, user CPU time, and system CPU time for your program and | |
11003 | its children. | |
6cf7e474 | 11004 | |
8e04817f AC |
11005 | @kindex info proc id |
11006 | @item info proc id | |
11007 | Report on the process IDs related to your program: its own process ID, | |
11008 | the ID of its parent, the process group ID, and the session ID. | |
104c1213 | 11009 | |
8e04817f AC |
11010 | @kindex info proc status |
11011 | @item info proc status | |
11012 | General information on the state of the process. If the process is | |
11013 | stopped, this report includes the reason for stopping, and any signal | |
11014 | received. | |
d4f3574e | 11015 | |
8e04817f AC |
11016 | @item info proc all |
11017 | Show all the above information about the process. | |
11018 | @end ignore | |
11019 | @end table | |
104c1213 | 11020 | |
8e04817f AC |
11021 | @node DJGPP Native |
11022 | @subsection Features for Debugging @sc{djgpp} Programs | |
11023 | @cindex @sc{djgpp} debugging | |
11024 | @cindex native @sc{djgpp} debugging | |
11025 | @cindex MS-DOS-specific commands | |
104c1213 | 11026 | |
8e04817f AC |
11027 | @sc{djgpp} is the port of @sc{gnu} development tools to MS-DOS and |
11028 | MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs | |
11029 | that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on | |
11030 | top of real-mode DOS systems and their emulations. | |
104c1213 | 11031 | |
8e04817f AC |
11032 | @value{GDBN} supports native debugging of @sc{djgpp} programs, and |
11033 | defines a few commands specific to the @sc{djgpp} port. This | |
11034 | subsection describes those commands. | |
104c1213 | 11035 | |
8e04817f AC |
11036 | @table @code |
11037 | @kindex info dos | |
11038 | @item info dos | |
11039 | This is a prefix of @sc{djgpp}-specific commands which print | |
11040 | information about the target system and important OS structures. | |
f1251bdd | 11041 | |
8e04817f AC |
11042 | @kindex sysinfo |
11043 | @cindex MS-DOS system info | |
11044 | @cindex free memory information (MS-DOS) | |
11045 | @item info dos sysinfo | |
11046 | This command displays assorted information about the underlying | |
11047 | platform: the CPU type and features, the OS version and flavor, the | |
11048 | DPMI version, and the available conventional and DPMI memory. | |
104c1213 | 11049 | |
8e04817f AC |
11050 | @cindex GDT |
11051 | @cindex LDT | |
11052 | @cindex IDT | |
11053 | @cindex segment descriptor tables | |
11054 | @cindex descriptor tables display | |
11055 | @item info dos gdt | |
11056 | @itemx info dos ldt | |
11057 | @itemx info dos idt | |
11058 | These 3 commands display entries from, respectively, Global, Local, | |
11059 | and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor | |
11060 | tables are data structures which store a descriptor for each segment | |
11061 | that is currently in use. The segment's selector is an index into a | |
11062 | descriptor table; the table entry for that index holds the | |
11063 | descriptor's base address and limit, and its attributes and access | |
11064 | rights. | |
104c1213 | 11065 | |
8e04817f AC |
11066 | A typical @sc{djgpp} program uses 3 segments: a code segment, a data |
11067 | segment (used for both data and the stack), and a DOS segment (which | |
11068 | allows access to DOS/BIOS data structures and absolute addresses in | |
11069 | conventional memory). However, the DPMI host will usually define | |
11070 | additional segments in order to support the DPMI environment. | |
d4f3574e | 11071 | |
8e04817f AC |
11072 | @cindex garbled pointers |
11073 | These commands allow to display entries from the descriptor tables. | |
11074 | Without an argument, all entries from the specified table are | |
11075 | displayed. An argument, which should be an integer expression, means | |
11076 | display a single entry whose index is given by the argument. For | |
11077 | example, here's a convenient way to display information about the | |
11078 | debugged program's data segment: | |
104c1213 | 11079 | |
8e04817f AC |
11080 | @smallexample |
11081 | @exdent @code{(@value{GDBP}) info dos ldt $ds} | |
11082 | @exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)} | |
11083 | @end smallexample | |
104c1213 | 11084 | |
8e04817f AC |
11085 | @noindent |
11086 | This comes in handy when you want to see whether a pointer is outside | |
11087 | the data segment's limit (i.e.@: @dfn{garbled}). | |
104c1213 | 11088 | |
8e04817f AC |
11089 | @cindex page tables display (MS-DOS) |
11090 | @item info dos pde | |
11091 | @itemx info dos pte | |
11092 | These two commands display entries from, respectively, the Page | |
11093 | Directory and the Page Tables. Page Directories and Page Tables are | |
11094 | data structures which control how virtual memory addresses are mapped | |
11095 | into physical addresses. A Page Table includes an entry for every | |
11096 | page of memory that is mapped into the program's address space; there | |
11097 | may be several Page Tables, each one holding up to 4096 entries. A | |
11098 | Page Directory has up to 4096 entries, one each for every Page Table | |
11099 | that is currently in use. | |
104c1213 | 11100 | |
8e04817f AC |
11101 | Without an argument, @kbd{info dos pde} displays the entire Page |
11102 | Directory, and @kbd{info dos pte} displays all the entries in all of | |
11103 | the Page Tables. An argument, an integer expression, given to the | |
11104 | @kbd{info dos pde} command means display only that entry from the Page | |
11105 | Directory table. An argument given to the @kbd{info dos pte} command | |
11106 | means display entries from a single Page Table, the one pointed to by | |
11107 | the specified entry in the Page Directory. | |
104c1213 | 11108 | |
8e04817f AC |
11109 | @cindex direct memory access (DMA) on MS-DOS |
11110 | These commands are useful when your program uses @dfn{DMA} (Direct | |
11111 | Memory Access), which needs physical addresses to program the DMA | |
11112 | controller. | |
104c1213 | 11113 | |
8e04817f | 11114 | These commands are supported only with some DPMI servers. |
104c1213 | 11115 | |
8e04817f AC |
11116 | @cindex physical address from linear address |
11117 | @item info dos address-pte @var{addr} | |
11118 | This command displays the Page Table entry for a specified linear | |
11119 | address. The argument linear address @var{addr} should already have the | |
11120 | appropriate segment's base address added to it, because this command | |
11121 | accepts addresses which may belong to @emph{any} segment. For | |
11122 | example, here's how to display the Page Table entry for the page where | |
11123 | the variable @code{i} is stored: | |
104c1213 | 11124 | |
8e04817f AC |
11125 | @smallexample |
11126 | @exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i} | |
11127 | @exdent @code{Page Table entry for address 0x11a00d30:} | |
11128 | @exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30} | |
11129 | @end smallexample | |
104c1213 | 11130 | |
8e04817f AC |
11131 | @noindent |
11132 | This says that @code{i} is stored at offset @code{0xd30} from the page | |
11133 | whose physical base address is @code{0x02698000}, and prints all the | |
11134 | attributes of that page. | |
104c1213 | 11135 | |
8e04817f AC |
11136 | Note that you must cast the addresses of variables to a @code{char *}, |
11137 | since otherwise the value of @code{__djgpp_base_address}, the base | |
11138 | address of all variables and functions in a @sc{djgpp} program, will | |
11139 | be added using the rules of C pointer arithmetics: if @code{i} is | |
11140 | declared an @code{int}, @value{GDBN} will add 4 times the value of | |
11141 | @code{__djgpp_base_address} to the address of @code{i}. | |
104c1213 | 11142 | |
8e04817f AC |
11143 | Here's another example, it displays the Page Table entry for the |
11144 | transfer buffer: | |
104c1213 | 11145 | |
8e04817f AC |
11146 | @smallexample |
11147 | @exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)} | |
11148 | @exdent @code{Page Table entry for address 0x29110:} | |
11149 | @exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110} | |
11150 | @end smallexample | |
104c1213 | 11151 | |
8e04817f AC |
11152 | @noindent |
11153 | (The @code{+ 3} offset is because the transfer buffer's address is the | |
11154 | 3rd member of the @code{_go32_info_block} structure.) The output of | |
11155 | this command clearly shows that addresses in conventional memory are | |
11156 | mapped 1:1, i.e.@: the physical and linear addresses are identical. | |
104c1213 | 11157 | |
8e04817f AC |
11158 | This command is supported only with some DPMI servers. |
11159 | @end table | |
104c1213 | 11160 | |
78c47bea PM |
11161 | @node Cygwin Native |
11162 | @subsection Features for Debugging MS Windows PE executables | |
11163 | @cindex MS Windows debugging | |
11164 | @cindex native Cygwin debugging | |
11165 | @cindex Cygwin-specific commands | |
11166 | ||
be448670 CF |
11167 | @value{GDBN} supports native debugging of MS Windows programs, including |
11168 | DLLs with and without symbolic debugging information. There are various | |
11169 | additional Cygwin-specific commands, described in this subsection. The | |
11170 | subsubsection @pxref{Non-debug DLL symbols} describes working with DLLs | |
11171 | that have no debugging symbols. | |
11172 | ||
78c47bea PM |
11173 | |
11174 | @table @code | |
11175 | @kindex info w32 | |
11176 | @item info w32 | |
11177 | This is a prefix of MS Windows specific commands which print | |
11178 | information about the target system and important OS structures. | |
11179 | ||
11180 | @item info w32 selector | |
11181 | This command displays information returned by | |
11182 | the Win32 API @code{GetThreadSelectorEntry} function. | |
11183 | It takes an optional argument that is evaluated to | |
11184 | a long value to give the information about this given selector. | |
11185 | Without argument, this command displays information | |
11186 | about the the six segment registers. | |
11187 | ||
11188 | @kindex info dll | |
11189 | @item info dll | |
11190 | This is a Cygwin specific alias of info shared. | |
11191 | ||
11192 | @kindex dll-symbols | |
11193 | @item dll-symbols | |
11194 | This command loads symbols from a dll similarly to | |
11195 | add-sym command but without the need to specify a base address. | |
11196 | ||
11197 | @kindex set new-console | |
11198 | @item set new-console @var{mode} | |
11199 | If @var{mode} is @code{on} the debuggee will | |
11200 | be started in a new console on next start. | |
11201 | If @var{mode} is @code{off}i, the debuggee will | |
11202 | be started in the same console as the debugger. | |
11203 | ||
11204 | @kindex show new-console | |
11205 | @item show new-console | |
11206 | Displays whether a new console is used | |
11207 | when the debuggee is started. | |
11208 | ||
11209 | @kindex set new-group | |
11210 | @item set new-group @var{mode} | |
11211 | This boolean value controls whether the debuggee should | |
11212 | start a new group or stay in the same group as the debugger. | |
11213 | This affects the way the Windows OS handles | |
11214 | Ctrl-C. | |
11215 | ||
11216 | @kindex show new-group | |
11217 | @item show new-group | |
11218 | Displays current value of new-group boolean. | |
11219 | ||
11220 | @kindex set debugevents | |
11221 | @item set debugevents | |
11222 | This boolean value adds debug output concerning events seen by the debugger. | |
11223 | ||
11224 | @kindex set debugexec | |
11225 | @item set debugexec | |
11226 | This boolean value adds debug output concerning execute events | |
11227 | seen by the debugger. | |
11228 | ||
11229 | @kindex set debugexceptions | |
11230 | @item set debugexceptions | |
11231 | This boolean value adds debug ouptut concerning exception events | |
11232 | seen by the debugger. | |
11233 | ||
11234 | @kindex set debugmemory | |
11235 | @item set debugmemory | |
11236 | This boolean value adds debug ouptut concerning memory events | |
11237 | seen by the debugger. | |
11238 | ||
11239 | @kindex set shell | |
11240 | @item set shell | |
11241 | This boolean values specifies whether the debuggee is called | |
11242 | via a shell or directly (default value is on). | |
11243 | ||
11244 | @kindex show shell | |
11245 | @item show shell | |
11246 | Displays if the debuggee will be started with a shell. | |
11247 | ||
11248 | @end table | |
11249 | ||
be448670 CF |
11250 | @menu |
11251 | * Non-debug DLL symbols:: Support for DLLs without debugging symbols | |
11252 | @end menu | |
11253 | ||
11254 | @node Non-debug DLL symbols | |
11255 | @subsubsection Support for DLLs without debugging symbols | |
11256 | @cindex DLLs with no debugging symbols | |
11257 | @cindex Minimal symbols and DLLs | |
11258 | ||
11259 | Very often on windows, some of the DLLs that your program relies on do | |
11260 | not include symbolic debugging information (for example, | |
11261 | @file{kernel32.dll}). When @value{GDBN} doesn't recognize any debugging | |
11262 | symbols in a DLL, it relies on the minimal amount of symbolic | |
11263 | information contained in the DLL's export table. This subsubsection | |
11264 | describes working with such symbols, known internally to @value{GDBN} as | |
11265 | ``minimal symbols''. | |
11266 | ||
11267 | Note that before the debugged program has started execution, no DLLs | |
11268 | will have been loaded. The easiest way around this problem is simply to | |
11269 | start the program --- either by setting a breakpoint or letting the | |
11270 | program run once to completion. It is also possible to force | |
11271 | @value{GDBN} to load a particular DLL before starting the executable --- | |
11272 | see the shared library information in @pxref{Files} or the | |
11273 | @code{dll-symbols} command in @pxref{Cygwin Native}. Currently, | |
11274 | explicitly loading symbols from a DLL with no debugging information will | |
11275 | cause the symbol names to be duplicated in @value{GDBN}'s lookup table, | |
11276 | which may adversely affect symbol lookup performance. | |
11277 | ||
11278 | @subsubsection DLL name prefixes | |
11279 | ||
11280 | In keeping with the naming conventions used by the Microsoft debugging | |
11281 | tools, DLL export symbols are made available with a prefix based on the | |
11282 | DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is | |
11283 | also entered into the symbol table, so @code{CreateFileA} is often | |
11284 | sufficient. In some cases there will be name clashes within a program | |
11285 | (particularly if the executable itself includes full debugging symbols) | |
11286 | necessitating the use of the fully qualified name when referring to the | |
11287 | contents of the DLL. Use single-quotes around the name to avoid the | |
11288 | exclamation mark (``!'') being interpreted as a language operator. | |
11289 | ||
11290 | Note that the internal name of the DLL may be all upper-case, even | |
11291 | though the file name of the DLL is lower-case, or vice-versa. Since | |
11292 | symbols within @value{GDBN} are @emph{case-sensitive} this may cause | |
11293 | some confusion. If in doubt, try the @code{info functions} and | |
11294 | @code{info variables} commands or even @code{maint print msymbols} (see | |
11295 | @pxref{Symbols}). Here's an example: | |
11296 | ||
11297 | @smallexample | |
11298 | (gdb) info function CreateFileA | |
11299 | All functions matching regular expression "CreateFileA": | |
11300 | ||
11301 | Non-debugging symbols: | |
11302 | 0x77e885f4 CreateFileA | |
11303 | 0x77e885f4 KERNEL32!CreateFileA | |
11304 | @end smallexample | |
11305 | ||
11306 | @smallexample | |
11307 | (gdb) info function ! | |
11308 | All functions matching regular expression "!": | |
11309 | ||
11310 | Non-debugging symbols: | |
11311 | 0x6100114c cygwin1!__assert | |
11312 | 0x61004034 cygwin1!_dll_crt0@@0 | |
11313 | 0x61004240 cygwin1!dll_crt0(per_process *) | |
11314 | [etc...] | |
11315 | @end smallexample | |
11316 | ||
11317 | @subsubsection Working with minimal symbols | |
11318 | ||
11319 | Symbols extracted from a DLL's export table do not contain very much | |
11320 | type information. All that @value{GDBN} can do is guess whether a symbol | |
11321 | refers to a function or variable depending on the linker section that | |
11322 | contains the symbol. Also note that the actual contents of the memory | |
11323 | contained in a DLL are not available unless the program is running. This | |
11324 | means that you cannot examine the contents of a variable or disassemble | |
11325 | a function within a DLL without a running program. | |
11326 | ||
11327 | Variables are generally treated as pointers and dereferenced | |
11328 | automatically. For this reason, it is often necessary to prefix a | |
11329 | variable name with the address-of operator (``&'') and provide explicit | |
11330 | type information in the command. Here's an example of the type of | |
11331 | problem: | |
11332 | ||
11333 | @smallexample | |
11334 | (gdb) print 'cygwin1!__argv' | |
11335 | $1 = 268572168 | |
11336 | @end smallexample | |
11337 | ||
11338 | @smallexample | |
11339 | (gdb) x 'cygwin1!__argv' | |
11340 | 0x10021610: "\230y\"" | |
11341 | @end smallexample | |
11342 | ||
11343 | And two possible solutions: | |
11344 | ||
11345 | @smallexample | |
11346 | (gdb) print ((char **)'cygwin1!__argv')[0] | |
11347 | $2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram" | |
11348 | @end smallexample | |
11349 | ||
11350 | @smallexample | |
11351 | (gdb) x/2x &'cygwin1!__argv' | |
11352 | 0x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000 | |
11353 | (gdb) x/x 0x10021608 | |
11354 | 0x10021608: 0x0022fd98 | |
11355 | (gdb) x/s 0x0022fd98 | |
11356 | 0x22fd98: "/cygdrive/c/mydirectory/myprogram" | |
11357 | @end smallexample | |
11358 | ||
11359 | Setting a break point within a DLL is possible even before the program | |
11360 | starts execution. However, under these circumstances, @value{GDBN} can't | |
11361 | examine the initial instructions of the function in order to skip the | |
11362 | function's frame set-up code. You can work around this by using ``*&'' | |
11363 | to set the breakpoint at a raw memory address: | |
11364 | ||
11365 | @smallexample | |
11366 | (gdb) break *&'python22!PyOS_Readline' | |
11367 | Breakpoint 1 at 0x1e04eff0 | |
11368 | @end smallexample | |
11369 | ||
11370 | The author of these extensions is not entirely convinced that setting a | |
11371 | break point within a shared DLL like @file{kernel32.dll} is completely | |
11372 | safe. | |
11373 | ||
8e04817f AC |
11374 | @node Embedded OS |
11375 | @section Embedded Operating Systems | |
104c1213 | 11376 | |
8e04817f AC |
11377 | This section describes configurations involving the debugging of |
11378 | embedded operating systems that are available for several different | |
11379 | architectures. | |
d4f3574e | 11380 | |
8e04817f AC |
11381 | @menu |
11382 | * VxWorks:: Using @value{GDBN} with VxWorks | |
11383 | @end menu | |
104c1213 | 11384 | |
8e04817f AC |
11385 | @value{GDBN} includes the ability to debug programs running on |
11386 | various real-time operating systems. | |
104c1213 | 11387 | |
8e04817f AC |
11388 | @node VxWorks |
11389 | @subsection Using @value{GDBN} with VxWorks | |
104c1213 | 11390 | |
8e04817f | 11391 | @cindex VxWorks |
104c1213 | 11392 | |
8e04817f | 11393 | @table @code |
104c1213 | 11394 | |
8e04817f AC |
11395 | @kindex target vxworks |
11396 | @item target vxworks @var{machinename} | |
11397 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} | |
11398 | is the target system's machine name or IP address. | |
104c1213 | 11399 | |
8e04817f | 11400 | @end table |
104c1213 | 11401 | |
8e04817f AC |
11402 | On VxWorks, @code{load} links @var{filename} dynamically on the |
11403 | current target system as well as adding its symbols in @value{GDBN}. | |
104c1213 | 11404 | |
8e04817f AC |
11405 | @value{GDBN} enables developers to spawn and debug tasks running on networked |
11406 | VxWorks targets from a Unix host. Already-running tasks spawned from | |
11407 | the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on | |
11408 | both the Unix host and on the VxWorks target. The program | |
11409 | @code{@value{GDBP}} is installed and executed on the Unix host. (It may be | |
11410 | installed with the name @code{vxgdb}, to distinguish it from a | |
11411 | @value{GDBN} for debugging programs on the host itself.) | |
104c1213 | 11412 | |
8e04817f AC |
11413 | @table @code |
11414 | @item VxWorks-timeout @var{args} | |
11415 | @kindex vxworks-timeout | |
11416 | All VxWorks-based targets now support the option @code{vxworks-timeout}. | |
11417 | This option is set by the user, and @var{args} represents the number of | |
11418 | seconds @value{GDBN} waits for responses to rpc's. You might use this if | |
11419 | your VxWorks target is a slow software simulator or is on the far side | |
11420 | of a thin network line. | |
11421 | @end table | |
104c1213 | 11422 | |
8e04817f AC |
11423 | The following information on connecting to VxWorks was current when |
11424 | this manual was produced; newer releases of VxWorks may use revised | |
11425 | procedures. | |
104c1213 | 11426 | |
8e04817f AC |
11427 | @kindex INCLUDE_RDB |
11428 | To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel | |
11429 | to include the remote debugging interface routines in the VxWorks | |
11430 | library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the | |
11431 | VxWorks configuration file @file{configAll.h} and rebuild your VxWorks | |
11432 | kernel. The resulting kernel contains @file{rdb.a}, and spawns the | |
11433 | source debugging task @code{tRdbTask} when VxWorks is booted. For more | |
11434 | information on configuring and remaking VxWorks, see the manufacturer's | |
11435 | manual. | |
11436 | @c VxWorks, see the @cite{VxWorks Programmer's Guide}. | |
104c1213 | 11437 | |
8e04817f AC |
11438 | Once you have included @file{rdb.a} in your VxWorks system image and set |
11439 | your Unix execution search path to find @value{GDBN}, you are ready to | |
11440 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or | |
11441 | @code{vxgdb}, depending on your installation). | |
104c1213 | 11442 | |
8e04817f | 11443 | @value{GDBN} comes up showing the prompt: |
104c1213 | 11444 | |
474c8240 | 11445 | @smallexample |
8e04817f | 11446 | (vxgdb) |
474c8240 | 11447 | @end smallexample |
104c1213 | 11448 | |
8e04817f AC |
11449 | @menu |
11450 | * VxWorks Connection:: Connecting to VxWorks | |
11451 | * VxWorks Download:: VxWorks download | |
11452 | * VxWorks Attach:: Running tasks | |
11453 | @end menu | |
104c1213 | 11454 | |
8e04817f AC |
11455 | @node VxWorks Connection |
11456 | @subsubsection Connecting to VxWorks | |
104c1213 | 11457 | |
8e04817f AC |
11458 | The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the |
11459 | network. To connect to a target whose host name is ``@code{tt}'', type: | |
104c1213 | 11460 | |
474c8240 | 11461 | @smallexample |
8e04817f | 11462 | (vxgdb) target vxworks tt |
474c8240 | 11463 | @end smallexample |
104c1213 | 11464 | |
8e04817f AC |
11465 | @need 750 |
11466 | @value{GDBN} displays messages like these: | |
104c1213 | 11467 | |
8e04817f AC |
11468 | @smallexample |
11469 | Attaching remote machine across net... | |
11470 | Connected to tt. | |
11471 | @end smallexample | |
104c1213 | 11472 | |
8e04817f AC |
11473 | @need 1000 |
11474 | @value{GDBN} then attempts to read the symbol tables of any object modules | |
11475 | loaded into the VxWorks target since it was last booted. @value{GDBN} locates | |
11476 | these files by searching the directories listed in the command search | |
11477 | path (@pxref{Environment, ,Your program's environment}); if it fails | |
11478 | to find an object file, it displays a message such as: | |
5d161b24 | 11479 | |
474c8240 | 11480 | @smallexample |
8e04817f | 11481 | prog.o: No such file or directory. |
474c8240 | 11482 | @end smallexample |
104c1213 | 11483 | |
8e04817f AC |
11484 | When this happens, add the appropriate directory to the search path with |
11485 | the @value{GDBN} command @code{path}, and execute the @code{target} | |
11486 | command again. | |
104c1213 | 11487 | |
8e04817f AC |
11488 | @node VxWorks Download |
11489 | @subsubsection VxWorks download | |
104c1213 | 11490 | |
8e04817f AC |
11491 | @cindex download to VxWorks |
11492 | If you have connected to the VxWorks target and you want to debug an | |
11493 | object that has not yet been loaded, you can use the @value{GDBN} | |
11494 | @code{load} command to download a file from Unix to VxWorks | |
11495 | incrementally. The object file given as an argument to the @code{load} | |
11496 | command is actually opened twice: first by the VxWorks target in order | |
11497 | to download the code, then by @value{GDBN} in order to read the symbol | |
11498 | table. This can lead to problems if the current working directories on | |
11499 | the two systems differ. If both systems have NFS mounted the same | |
11500 | filesystems, you can avoid these problems by using absolute paths. | |
11501 | Otherwise, it is simplest to set the working directory on both systems | |
11502 | to the directory in which the object file resides, and then to reference | |
11503 | the file by its name, without any path. For instance, a program | |
11504 | @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks | |
11505 | and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this | |
11506 | program, type this on VxWorks: | |
104c1213 | 11507 | |
474c8240 | 11508 | @smallexample |
8e04817f | 11509 | -> cd "@var{vxpath}/vw/demo/rdb" |
474c8240 | 11510 | @end smallexample |
104c1213 | 11511 | |
8e04817f AC |
11512 | @noindent |
11513 | Then, in @value{GDBN}, type: | |
104c1213 | 11514 | |
474c8240 | 11515 | @smallexample |
8e04817f AC |
11516 | (vxgdb) cd @var{hostpath}/vw/demo/rdb |
11517 | (vxgdb) load prog.o | |
474c8240 | 11518 | @end smallexample |
104c1213 | 11519 | |
8e04817f | 11520 | @value{GDBN} displays a response similar to this: |
104c1213 | 11521 | |
8e04817f AC |
11522 | @smallexample |
11523 | Reading symbol data from wherever/vw/demo/rdb/prog.o... done. | |
11524 | @end smallexample | |
104c1213 | 11525 | |
8e04817f AC |
11526 | You can also use the @code{load} command to reload an object module |
11527 | after editing and recompiling the corresponding source file. Note that | |
11528 | this makes @value{GDBN} delete all currently-defined breakpoints, | |
11529 | auto-displays, and convenience variables, and to clear the value | |
11530 | history. (This is necessary in order to preserve the integrity of | |
11531 | debugger's data structures that reference the target system's symbol | |
11532 | table.) | |
104c1213 | 11533 | |
8e04817f AC |
11534 | @node VxWorks Attach |
11535 | @subsubsection Running tasks | |
104c1213 JM |
11536 | |
11537 | @cindex running VxWorks tasks | |
11538 | You can also attach to an existing task using the @code{attach} command as | |
11539 | follows: | |
11540 | ||
474c8240 | 11541 | @smallexample |
104c1213 | 11542 | (vxgdb) attach @var{task} |
474c8240 | 11543 | @end smallexample |
104c1213 JM |
11544 | |
11545 | @noindent | |
11546 | where @var{task} is the VxWorks hexadecimal task ID. The task can be running | |
11547 | or suspended when you attach to it. Running tasks are suspended at | |
11548 | the time of attachment. | |
11549 | ||
6d2ebf8b | 11550 | @node Embedded Processors |
104c1213 JM |
11551 | @section Embedded Processors |
11552 | ||
11553 | This section goes into details specific to particular embedded | |
11554 | configurations. | |
11555 | ||
7d86b5d5 | 11556 | |
104c1213 | 11557 | @menu |
104c1213 JM |
11558 | * ARM:: ARM |
11559 | * H8/300:: Hitachi H8/300 | |
11560 | * H8/500:: Hitachi H8/500 | |
104c1213 JM |
11561 | * M32R/D:: Mitsubishi M32R/D |
11562 | * M68K:: Motorola M68K | |
104c1213 | 11563 | * MIPS Embedded:: MIPS Embedded |
a37295f9 | 11564 | * OpenRISC 1000:: OpenRisc 1000 |
104c1213 JM |
11565 | * PA:: HP PA Embedded |
11566 | * PowerPC: PowerPC | |
11567 | * SH:: Hitachi SH | |
11568 | * Sparclet:: Tsqware Sparclet | |
11569 | * Sparclite:: Fujitsu Sparclite | |
11570 | * ST2000:: Tandem ST2000 | |
11571 | * Z8000:: Zilog Z8000 | |
11572 | @end menu | |
11573 | ||
6d2ebf8b | 11574 | @node ARM |
104c1213 JM |
11575 | @subsection ARM |
11576 | ||
11577 | @table @code | |
11578 | ||
8e04817f AC |
11579 | @kindex target rdi |
11580 | @item target rdi @var{dev} | |
11581 | ARM Angel monitor, via RDI library interface to ADP protocol. You may | |
11582 | use this target to communicate with both boards running the Angel | |
11583 | monitor, or with the EmbeddedICE JTAG debug device. | |
11584 | ||
11585 | @kindex target rdp | |
11586 | @item target rdp @var{dev} | |
11587 | ARM Demon monitor. | |
11588 | ||
11589 | @end table | |
11590 | ||
11591 | @node H8/300 | |
11592 | @subsection Hitachi H8/300 | |
11593 | ||
11594 | @table @code | |
11595 | ||
11596 | @kindex target hms@r{, with H8/300} | |
11597 | @item target hms @var{dev} | |
11598 | A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. | |
11599 | Use special commands @code{device} and @code{speed} to control the serial | |
11600 | line and the communications speed used. | |
11601 | ||
11602 | @kindex target e7000@r{, with H8/300} | |
11603 | @item target e7000 @var{dev} | |
11604 | E7000 emulator for Hitachi H8 and SH. | |
11605 | ||
11606 | @kindex target sh3@r{, with H8/300} | |
11607 | @kindex target sh3e@r{, with H8/300} | |
11608 | @item target sh3 @var{dev} | |
11609 | @itemx target sh3e @var{dev} | |
11610 | Hitachi SH-3 and SH-3E target systems. | |
11611 | ||
11612 | @end table | |
11613 | ||
11614 | @cindex download to H8/300 or H8/500 | |
11615 | @cindex H8/300 or H8/500 download | |
11616 | @cindex download to Hitachi SH | |
11617 | @cindex Hitachi SH download | |
11618 | When you select remote debugging to a Hitachi SH, H8/300, or H8/500 | |
11619 | board, the @code{load} command downloads your program to the Hitachi | |
11620 | board and also opens it as the current executable target for | |
11621 | @value{GDBN} on your host (like the @code{file} command). | |
11622 | ||
11623 | @value{GDBN} needs to know these things to talk to your | |
11624 | Hitachi SH, H8/300, or H8/500: | |
11625 | ||
11626 | @enumerate | |
11627 | @item | |
11628 | that you want to use @samp{target hms}, the remote debugging interface | |
11629 | for Hitachi microprocessors, or @samp{target e7000}, the in-circuit | |
11630 | emulator for the Hitachi SH and the Hitachi 300H. (@samp{target hms} is | |
11631 | the default when @value{GDBN} is configured specifically for the Hitachi SH, | |
11632 | H8/300, or H8/500.) | |
11633 | ||
11634 | @item | |
11635 | what serial device connects your host to your Hitachi board (the first | |
11636 | serial device available on your host is the default). | |
11637 | ||
11638 | @item | |
11639 | what speed to use over the serial device. | |
11640 | @end enumerate | |
11641 | ||
11642 | @menu | |
11643 | * Hitachi Boards:: Connecting to Hitachi boards. | |
11644 | * Hitachi ICE:: Using the E7000 In-Circuit Emulator. | |
11645 | * Hitachi Special:: Special @value{GDBN} commands for Hitachi micros. | |
11646 | @end menu | |
11647 | ||
11648 | @node Hitachi Boards | |
11649 | @subsubsection Connecting to Hitachi boards | |
11650 | ||
11651 | @c only for Unix hosts | |
11652 | @kindex device | |
11653 | @cindex serial device, Hitachi micros | |
11654 | Use the special @code{@value{GDBN}} command @samp{device @var{port}} if you | |
11655 | need to explicitly set the serial device. The default @var{port} is the | |
11656 | first available port on your host. This is only necessary on Unix | |
11657 | hosts, where it is typically something like @file{/dev/ttya}. | |
11658 | ||
11659 | @kindex speed | |
11660 | @cindex serial line speed, Hitachi micros | |
11661 | @code{@value{GDBN}} has another special command to set the communications | |
11662 | speed: @samp{speed @var{bps}}. This command also is only used from Unix | |
11663 | hosts; on DOS hosts, set the line speed as usual from outside @value{GDBN} with | |
11664 | the DOS @code{mode} command (for instance, | |
11665 | @w{@kbd{mode com2:9600,n,8,1,p}} for a 9600@dmn{bps} connection). | |
11666 | ||
11667 | The @samp{device} and @samp{speed} commands are available only when you | |
11668 | use a Unix host to debug your Hitachi microprocessor programs. If you | |
11669 | use a DOS host, | |
11670 | @value{GDBN} depends on an auxiliary terminate-and-stay-resident program | |
11671 | called @code{asynctsr} to communicate with the development board | |
11672 | through a PC serial port. You must also use the DOS @code{mode} command | |
11673 | to set up the serial port on the DOS side. | |
11674 | ||
11675 | The following sample session illustrates the steps needed to start a | |
11676 | program under @value{GDBN} control on an H8/300. The example uses a | |
11677 | sample H8/300 program called @file{t.x}. The procedure is the same for | |
11678 | the Hitachi SH and the H8/500. | |
11679 | ||
11680 | First hook up your development board. In this example, we use a | |
11681 | board attached to serial port @code{COM2}; if you use a different serial | |
11682 | port, substitute its name in the argument of the @code{mode} command. | |
11683 | When you call @code{asynctsr}, the auxiliary comms program used by the | |
11684 | debugger, you give it just the numeric part of the serial port's name; | |
11685 | for example, @samp{asyncstr 2} below runs @code{asyncstr} on | |
11686 | @code{COM2}. | |
11687 | ||
474c8240 | 11688 | @smallexample |
8e04817f AC |
11689 | C:\H8300\TEST> asynctsr 2 |
11690 | C:\H8300\TEST> mode com2:9600,n,8,1,p | |
11691 | ||
11692 | Resident portion of MODE loaded | |
11693 | ||
11694 | COM2: 9600, n, 8, 1, p | |
11695 | ||
474c8240 | 11696 | @end smallexample |
8e04817f AC |
11697 | |
11698 | @quotation | |
11699 | @emph{Warning:} We have noticed a bug in PC-NFS that conflicts with | |
11700 | @code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to | |
11701 | disable it, or even boot without it, to use @code{asynctsr} to control | |
11702 | your development board. | |
11703 | @end quotation | |
11704 | ||
11705 | @kindex target hms@r{, and serial protocol} | |
11706 | Now that serial communications are set up, and the development board is | |
11707 | connected, you can start up @value{GDBN}. Call @code{@value{GDBP}} with | |
11708 | the name of your program as the argument. @code{@value{GDBN}} prompts | |
11709 | you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special | |
11710 | commands to begin your debugging session: @samp{target hms} to specify | |
11711 | cross-debugging to the Hitachi board, and the @code{load} command to | |
11712 | download your program to the board. @code{load} displays the names of | |
11713 | the program's sections, and a @samp{*} for each 2K of data downloaded. | |
11714 | (If you want to refresh @value{GDBN} data on symbols or on the | |
11715 | executable file without downloading, use the @value{GDBN} commands | |
11716 | @code{file} or @code{symbol-file}. These commands, and @code{load} | |
11717 | itself, are described in @ref{Files,,Commands to specify files}.) | |
11718 | ||
11719 | @smallexample | |
11720 | (eg-C:\H8300\TEST) @value{GDBP} t.x | |
11721 | @value{GDBN} is free software and you are welcome to distribute copies | |
11722 | of it under certain conditions; type "show copying" to see | |
11723 | the conditions. | |
11724 | There is absolutely no warranty for @value{GDBN}; type "show warranty" | |
11725 | for details. | |
11726 | @value{GDBN} @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc... | |
11727 | (@value{GDBP}) target hms | |
11728 | Connected to remote H8/300 HMS system. | |
11729 | (@value{GDBP}) load t.x | |
11730 | .text : 0x8000 .. 0xabde *********** | |
11731 | .data : 0xabde .. 0xad30 * | |
11732 | .stack : 0xf000 .. 0xf014 * | |
11733 | @end smallexample | |
11734 | ||
11735 | At this point, you're ready to run or debug your program. From here on, | |
11736 | you can use all the usual @value{GDBN} commands. The @code{break} command | |
11737 | sets breakpoints; the @code{run} command starts your program; | |
11738 | @code{print} or @code{x} display data; the @code{continue} command | |
11739 | resumes execution after stopping at a breakpoint. You can use the | |
11740 | @code{help} command at any time to find out more about @value{GDBN} commands. | |
11741 | ||
11742 | Remember, however, that @emph{operating system} facilities aren't | |
11743 | available on your development board; for example, if your program hangs, | |
11744 | you can't send an interrupt---but you can press the @sc{reset} switch! | |
11745 | ||
11746 | Use the @sc{reset} button on the development board | |
11747 | @itemize @bullet | |
11748 | @item | |
11749 | to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has | |
11750 | no way to pass an interrupt signal to the development board); and | |
11751 | ||
11752 | @item | |
11753 | to return to the @value{GDBN} command prompt after your program finishes | |
11754 | normally. The communications protocol provides no other way for @value{GDBN} | |
11755 | to detect program completion. | |
11756 | @end itemize | |
11757 | ||
11758 | In either case, @value{GDBN} sees the effect of a @sc{reset} on the | |
11759 | development board as a ``normal exit'' of your program. | |
11760 | ||
11761 | @node Hitachi ICE | |
11762 | @subsubsection Using the E7000 in-circuit emulator | |
11763 | ||
11764 | @kindex target e7000@r{, with Hitachi ICE} | |
11765 | You can use the E7000 in-circuit emulator to develop code for either the | |
11766 | Hitachi SH or the H8/300H. Use one of these forms of the @samp{target | |
11767 | e7000} command to connect @value{GDBN} to your E7000: | |
11768 | ||
11769 | @table @code | |
11770 | @item target e7000 @var{port} @var{speed} | |
11771 | Use this form if your E7000 is connected to a serial port. The | |
11772 | @var{port} argument identifies what serial port to use (for example, | |
11773 | @samp{com2}). The third argument is the line speed in bits per second | |
11774 | (for example, @samp{9600}). | |
11775 | ||
11776 | @item target e7000 @var{hostname} | |
11777 | If your E7000 is installed as a host on a TCP/IP network, you can just | |
11778 | specify its hostname; @value{GDBN} uses @code{telnet} to connect. | |
11779 | @end table | |
11780 | ||
11781 | @node Hitachi Special | |
11782 | @subsubsection Special @value{GDBN} commands for Hitachi micros | |
11783 | ||
11784 | Some @value{GDBN} commands are available only for the H8/300: | |
11785 | ||
11786 | @table @code | |
11787 | ||
11788 | @kindex set machine | |
11789 | @kindex show machine | |
11790 | @item set machine h8300 | |
11791 | @itemx set machine h8300h | |
11792 | Condition @value{GDBN} for one of the two variants of the H8/300 | |
11793 | architecture with @samp{set machine}. You can use @samp{show machine} | |
11794 | to check which variant is currently in effect. | |
104c1213 JM |
11795 | |
11796 | @end table | |
11797 | ||
8e04817f AC |
11798 | @node H8/500 |
11799 | @subsection H8/500 | |
104c1213 JM |
11800 | |
11801 | @table @code | |
11802 | ||
8e04817f AC |
11803 | @kindex set memory @var{mod} |
11804 | @cindex memory models, H8/500 | |
11805 | @item set memory @var{mod} | |
11806 | @itemx show memory | |
11807 | Specify which H8/500 memory model (@var{mod}) you are using with | |
11808 | @samp{set memory}; check which memory model is in effect with @samp{show | |
11809 | memory}. The accepted values for @var{mod} are @code{small}, | |
11810 | @code{big}, @code{medium}, and @code{compact}. | |
104c1213 | 11811 | |
8e04817f | 11812 | @end table |
104c1213 | 11813 | |
8e04817f AC |
11814 | @node M32R/D |
11815 | @subsection Mitsubishi M32R/D | |
11816 | ||
11817 | @table @code | |
11818 | ||
11819 | @kindex target m32r | |
11820 | @item target m32r @var{dev} | |
11821 | Mitsubishi M32R/D ROM monitor. | |
11822 | ||
11823 | @end table | |
11824 | ||
11825 | @node M68K | |
11826 | @subsection M68k | |
11827 | ||
11828 | The Motorola m68k configuration includes ColdFire support, and | |
11829 | target command for the following ROM monitors. | |
11830 | ||
11831 | @table @code | |
11832 | ||
11833 | @kindex target abug | |
11834 | @item target abug @var{dev} | |
11835 | ABug ROM monitor for M68K. | |
11836 | ||
11837 | @kindex target cpu32bug | |
11838 | @item target cpu32bug @var{dev} | |
11839 | CPU32BUG monitor, running on a CPU32 (M68K) board. | |
11840 | ||
11841 | @kindex target dbug | |
11842 | @item target dbug @var{dev} | |
11843 | dBUG ROM monitor for Motorola ColdFire. | |
11844 | ||
11845 | @kindex target est | |
11846 | @item target est @var{dev} | |
11847 | EST-300 ICE monitor, running on a CPU32 (M68K) board. | |
11848 | ||
11849 | @kindex target rom68k | |
11850 | @item target rom68k @var{dev} | |
11851 | ROM 68K monitor, running on an M68K IDP board. | |
11852 | ||
11853 | @end table | |
11854 | ||
8e04817f AC |
11855 | @table @code |
11856 | ||
11857 | @kindex target rombug | |
11858 | @item target rombug @var{dev} | |
11859 | ROMBUG ROM monitor for OS/9000. | |
11860 | ||
11861 | @end table | |
11862 | ||
8e04817f AC |
11863 | @node MIPS Embedded |
11864 | @subsection MIPS Embedded | |
11865 | ||
11866 | @cindex MIPS boards | |
11867 | @value{GDBN} can use the MIPS remote debugging protocol to talk to a | |
11868 | MIPS board attached to a serial line. This is available when | |
11869 | you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. | |
104c1213 | 11870 | |
8e04817f AC |
11871 | @need 1000 |
11872 | Use these @value{GDBN} commands to specify the connection to your target board: | |
104c1213 | 11873 | |
8e04817f AC |
11874 | @table @code |
11875 | @item target mips @var{port} | |
11876 | @kindex target mips @var{port} | |
11877 | To run a program on the board, start up @code{@value{GDBP}} with the | |
11878 | name of your program as the argument. To connect to the board, use the | |
11879 | command @samp{target mips @var{port}}, where @var{port} is the name of | |
11880 | the serial port connected to the board. If the program has not already | |
11881 | been downloaded to the board, you may use the @code{load} command to | |
11882 | download it. You can then use all the usual @value{GDBN} commands. | |
104c1213 | 11883 | |
8e04817f AC |
11884 | For example, this sequence connects to the target board through a serial |
11885 | port, and loads and runs a program called @var{prog} through the | |
11886 | debugger: | |
104c1213 | 11887 | |
474c8240 | 11888 | @smallexample |
8e04817f AC |
11889 | host$ @value{GDBP} @var{prog} |
11890 | @value{GDBN} is free software and @dots{} | |
11891 | (@value{GDBP}) target mips /dev/ttyb | |
11892 | (@value{GDBP}) load @var{prog} | |
11893 | (@value{GDBP}) run | |
474c8240 | 11894 | @end smallexample |
104c1213 | 11895 | |
8e04817f AC |
11896 | @item target mips @var{hostname}:@var{portnumber} |
11897 | On some @value{GDBN} host configurations, you can specify a TCP | |
11898 | connection (for instance, to a serial line managed by a terminal | |
11899 | concentrator) instead of a serial port, using the syntax | |
11900 | @samp{@var{hostname}:@var{portnumber}}. | |
104c1213 | 11901 | |
8e04817f AC |
11902 | @item target pmon @var{port} |
11903 | @kindex target pmon @var{port} | |
11904 | PMON ROM monitor. | |
104c1213 | 11905 | |
8e04817f AC |
11906 | @item target ddb @var{port} |
11907 | @kindex target ddb @var{port} | |
11908 | NEC's DDB variant of PMON for Vr4300. | |
104c1213 | 11909 | |
8e04817f AC |
11910 | @item target lsi @var{port} |
11911 | @kindex target lsi @var{port} | |
11912 | LSI variant of PMON. | |
104c1213 | 11913 | |
8e04817f AC |
11914 | @kindex target r3900 |
11915 | @item target r3900 @var{dev} | |
11916 | Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips. | |
104c1213 | 11917 | |
8e04817f AC |
11918 | @kindex target array |
11919 | @item target array @var{dev} | |
11920 | Array Tech LSI33K RAID controller board. | |
104c1213 | 11921 | |
8e04817f | 11922 | @end table |
104c1213 | 11923 | |
104c1213 | 11924 | |
8e04817f AC |
11925 | @noindent |
11926 | @value{GDBN} also supports these special commands for MIPS targets: | |
104c1213 | 11927 | |
8e04817f AC |
11928 | @table @code |
11929 | @item set processor @var{args} | |
11930 | @itemx show processor | |
11931 | @kindex set processor @var{args} | |
11932 | @kindex show processor | |
11933 | Use the @code{set processor} command to set the type of MIPS | |
11934 | processor when you want to access processor-type-specific registers. | |
11935 | For example, @code{set processor @var{r3041}} tells @value{GDBN} | |
11936 | to use the CPU registers appropriate for the 3041 chip. | |
11937 | Use the @code{show processor} command to see what MIPS processor @value{GDBN} | |
11938 | is using. Use the @code{info reg} command to see what registers | |
11939 | @value{GDBN} is using. | |
104c1213 | 11940 | |
8e04817f AC |
11941 | @item set mipsfpu double |
11942 | @itemx set mipsfpu single | |
11943 | @itemx set mipsfpu none | |
11944 | @itemx show mipsfpu | |
11945 | @kindex set mipsfpu | |
11946 | @kindex show mipsfpu | |
11947 | @cindex MIPS remote floating point | |
11948 | @cindex floating point, MIPS remote | |
11949 | If your target board does not support the MIPS floating point | |
11950 | coprocessor, you should use the command @samp{set mipsfpu none} (if you | |
11951 | need this, you may wish to put the command in your @value{GDBN} init | |
11952 | file). This tells @value{GDBN} how to find the return value of | |
11953 | functions which return floating point values. It also allows | |
11954 | @value{GDBN} to avoid saving the floating point registers when calling | |
11955 | functions on the board. If you are using a floating point coprocessor | |
11956 | with only single precision floating point support, as on the @sc{r4650} | |
11957 | processor, use the command @samp{set mipsfpu single}. The default | |
11958 | double precision floating point coprocessor may be selected using | |
11959 | @samp{set mipsfpu double}. | |
104c1213 | 11960 | |
8e04817f AC |
11961 | In previous versions the only choices were double precision or no |
11962 | floating point, so @samp{set mipsfpu on} will select double precision | |
11963 | and @samp{set mipsfpu off} will select no floating point. | |
104c1213 | 11964 | |
8e04817f AC |
11965 | As usual, you can inquire about the @code{mipsfpu} variable with |
11966 | @samp{show mipsfpu}. | |
104c1213 | 11967 | |
8e04817f AC |
11968 | @item set remotedebug @var{n} |
11969 | @itemx show remotedebug | |
11970 | @kindex set remotedebug@r{, MIPS protocol} | |
11971 | @kindex show remotedebug@r{, MIPS protocol} | |
11972 | @cindex @code{remotedebug}, MIPS protocol | |
11973 | @cindex MIPS @code{remotedebug} protocol | |
11974 | @c FIXME! For this to be useful, you must know something about the MIPS | |
11975 | @c FIXME...protocol. Where is it described? | |
11976 | You can see some debugging information about communications with the board | |
11977 | by setting the @code{remotedebug} variable. If you set it to @code{1} using | |
11978 | @samp{set remotedebug 1}, every packet is displayed. If you set it | |
11979 | to @code{2}, every character is displayed. You can check the current value | |
11980 | at any time with the command @samp{show remotedebug}. | |
104c1213 | 11981 | |
8e04817f AC |
11982 | @item set timeout @var{seconds} |
11983 | @itemx set retransmit-timeout @var{seconds} | |
11984 | @itemx show timeout | |
11985 | @itemx show retransmit-timeout | |
11986 | @cindex @code{timeout}, MIPS protocol | |
11987 | @cindex @code{retransmit-timeout}, MIPS protocol | |
11988 | @kindex set timeout | |
11989 | @kindex show timeout | |
11990 | @kindex set retransmit-timeout | |
11991 | @kindex show retransmit-timeout | |
11992 | You can control the timeout used while waiting for a packet, in the MIPS | |
11993 | remote protocol, with the @code{set timeout @var{seconds}} command. The | |
11994 | default is 5 seconds. Similarly, you can control the timeout used while | |
11995 | waiting for an acknowledgement of a packet with the @code{set | |
11996 | retransmit-timeout @var{seconds}} command. The default is 3 seconds. | |
11997 | You can inspect both values with @code{show timeout} and @code{show | |
11998 | retransmit-timeout}. (These commands are @emph{only} available when | |
11999 | @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) | |
104c1213 | 12000 | |
8e04817f AC |
12001 | The timeout set by @code{set timeout} does not apply when @value{GDBN} |
12002 | is waiting for your program to stop. In that case, @value{GDBN} waits | |
12003 | forever because it has no way of knowing how long the program is going | |
12004 | to run before stopping. | |
12005 | @end table | |
104c1213 | 12006 | |
a37295f9 MM |
12007 | @node OpenRISC 1000 |
12008 | @subsection OpenRISC 1000 | |
12009 | @cindex OpenRISC 1000 | |
12010 | ||
12011 | @cindex or1k boards | |
12012 | See OR1k Architecture document (@uref{www.opencores.org}) for more information | |
12013 | about platform and commands. | |
12014 | ||
12015 | @table @code | |
12016 | ||
12017 | @kindex target jtag | |
12018 | @item target jtag jtag://@var{host}:@var{port} | |
12019 | ||
12020 | Connects to remote JTAG server. | |
12021 | JTAG remote server can be either an or1ksim or JTAG server, | |
12022 | connected via parallel port to the board. | |
12023 | ||
12024 | Example: @code{target jtag jtag://localhost:9999} | |
12025 | ||
12026 | @kindex or1ksim | |
12027 | @item or1ksim @var{command} | |
12028 | If connected to @code{or1ksim} OpenRISC 1000 Architectural | |
12029 | Simulator, proprietary commands can be executed. | |
12030 | ||
12031 | @kindex info or1k spr | |
12032 | @item info or1k spr | |
12033 | Displays spr groups. | |
12034 | ||
12035 | @item info or1k spr @var{group} | |
12036 | @itemx info or1k spr @var{groupno} | |
12037 | Displays register names in selected group. | |
12038 | ||
12039 | @item info or1k spr @var{group} @var{register} | |
12040 | @itemx info or1k spr @var{register} | |
12041 | @itemx info or1k spr @var{groupno} @var{registerno} | |
12042 | @itemx info or1k spr @var{registerno} | |
12043 | Shows information about specified spr register. | |
12044 | ||
12045 | @kindex spr | |
12046 | @item spr @var{group} @var{register} @var{value} | |
12047 | @itemx spr @var{register @var{value}} | |
12048 | @itemx spr @var{groupno} @var{registerno @var{value}} | |
12049 | @itemx spr @var{registerno @var{value}} | |
12050 | Writes @var{value} to specified spr register. | |
12051 | @end table | |
12052 | ||
12053 | Some implementations of OpenRISC 1000 Architecture also have hardware trace. | |
12054 | It is very similar to @value{GDBN} trace, except it does not interfere with normal | |
12055 | program execution and is thus much faster. Hardware breakpoints/watchpoint | |
12056 | triggers can be set using: | |
12057 | @table @code | |
12058 | @item $LEA/$LDATA | |
12059 | Load effective address/data | |
12060 | @item $SEA/$SDATA | |
12061 | Store effective address/data | |
12062 | @item $AEA/$ADATA | |
12063 | Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA) | |
12064 | @item $FETCH | |
12065 | Fetch data | |
12066 | @end table | |
12067 | ||
12068 | When triggered, it can capture low level data, like: @code{PC}, @code{LSEA}, | |
12069 | @code{LDATA}, @code{SDATA}, @code{READSPR}, @code{WRITESPR}, @code{INSTR}. | |
12070 | ||
12071 | @code{htrace} commands: | |
12072 | @cindex OpenRISC 1000 htrace | |
12073 | @table @code | |
12074 | @kindex hwatch | |
12075 | @item hwatch @var{conditional} | |
12076 | Set hardware watchpoint on combination of Load/Store Effecive Address(es) | |
12077 | or Data. For example: | |
12078 | ||
12079 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} | |
12080 | ||
12081 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} | |
12082 | ||
12083 | @kindex htrace info | |
12084 | @item htrace info | |
12085 | Display information about current HW trace configuration. | |
12086 | ||
12087 | @kindex htrace trigger | |
12088 | @item htrace trigger @var{conditional} | |
12089 | Set starting criteria for HW trace. | |
12090 | ||
12091 | @kindex htrace qualifier | |
12092 | @item htrace qualifier @var{conditional} | |
12093 | Set acquisition qualifier for HW trace. | |
12094 | ||
12095 | @kindex htrace stop | |
12096 | @item htrace stop @var{conditional} | |
12097 | Set HW trace stopping criteria. | |
12098 | ||
12099 | @kindex htrace record | |
f153cc92 | 12100 | @item htrace record [@var{data}]* |
a37295f9 MM |
12101 | Selects the data to be recorded, when qualifier is met and HW trace was |
12102 | triggered. | |
12103 | ||
12104 | @kindex htrace enable | |
12105 | @item htrace enable | |
12106 | @kindex htrace disable | |
12107 | @itemx htrace disable | |
12108 | Enables/disables the HW trace. | |
12109 | ||
12110 | @kindex htrace rewind | |
f153cc92 | 12111 | @item htrace rewind [@var{filename}] |
a37295f9 MM |
12112 | Clears currently recorded trace data. |
12113 | ||
12114 | If filename is specified, new trace file is made and any newly collected data | |
12115 | will be written there. | |
12116 | ||
12117 | @kindex htrace print | |
f153cc92 | 12118 | @item htrace print [@var{start} [@var{len}]] |
a37295f9 MM |
12119 | Prints trace buffer, using current record configuration. |
12120 | ||
12121 | @kindex htrace mode continuous | |
12122 | @item htrace mode continuous | |
12123 | Set continuous trace mode. | |
12124 | ||
12125 | @kindex htrace mode suspend | |
12126 | @item htrace mode suspend | |
12127 | Set suspend trace mode. | |
12128 | ||
12129 | @end table | |
12130 | ||
8e04817f AC |
12131 | @node PowerPC |
12132 | @subsection PowerPC | |
104c1213 JM |
12133 | |
12134 | @table @code | |
104c1213 | 12135 | |
8e04817f AC |
12136 | @kindex target dink32 |
12137 | @item target dink32 @var{dev} | |
12138 | DINK32 ROM monitor. | |
104c1213 | 12139 | |
8e04817f AC |
12140 | @kindex target ppcbug |
12141 | @item target ppcbug @var{dev} | |
12142 | @kindex target ppcbug1 | |
12143 | @item target ppcbug1 @var{dev} | |
12144 | PPCBUG ROM monitor for PowerPC. | |
104c1213 | 12145 | |
8e04817f AC |
12146 | @kindex target sds |
12147 | @item target sds @var{dev} | |
12148 | SDS monitor, running on a PowerPC board (such as Motorola's ADS). | |
12149 | ||
12150 | @end table | |
12151 | ||
12152 | @node PA | |
12153 | @subsection HP PA Embedded | |
104c1213 JM |
12154 | |
12155 | @table @code | |
12156 | ||
8e04817f AC |
12157 | @kindex target op50n |
12158 | @item target op50n @var{dev} | |
12159 | OP50N monitor, running on an OKI HPPA board. | |
12160 | ||
12161 | @kindex target w89k | |
12162 | @item target w89k @var{dev} | |
12163 | W89K monitor, running on a Winbond HPPA board. | |
104c1213 JM |
12164 | |
12165 | @end table | |
12166 | ||
8e04817f AC |
12167 | @node SH |
12168 | @subsection Hitachi SH | |
104c1213 JM |
12169 | |
12170 | @table @code | |
12171 | ||
8e04817f AC |
12172 | @kindex target hms@r{, with Hitachi SH} |
12173 | @item target hms @var{dev} | |
12174 | A Hitachi SH board attached via serial line to your host. Use special | |
12175 | commands @code{device} and @code{speed} to control the serial line and | |
12176 | the communications speed used. | |
104c1213 | 12177 | |
8e04817f AC |
12178 | @kindex target e7000@r{, with Hitachi SH} |
12179 | @item target e7000 @var{dev} | |
12180 | E7000 emulator for Hitachi SH. | |
104c1213 | 12181 | |
8e04817f AC |
12182 | @kindex target sh3@r{, with SH} |
12183 | @kindex target sh3e@r{, with SH} | |
12184 | @item target sh3 @var{dev} | |
12185 | @item target sh3e @var{dev} | |
12186 | Hitachi SH-3 and SH-3E target systems. | |
104c1213 | 12187 | |
8e04817f | 12188 | @end table |
104c1213 | 12189 | |
8e04817f AC |
12190 | @node Sparclet |
12191 | @subsection Tsqware Sparclet | |
104c1213 | 12192 | |
8e04817f AC |
12193 | @cindex Sparclet |
12194 | ||
12195 | @value{GDBN} enables developers to debug tasks running on | |
12196 | Sparclet targets from a Unix host. | |
12197 | @value{GDBN} uses code that runs on | |
12198 | both the Unix host and on the Sparclet target. The program | |
12199 | @code{@value{GDBP}} is installed and executed on the Unix host. | |
104c1213 | 12200 | |
8e04817f AC |
12201 | @table @code |
12202 | @item remotetimeout @var{args} | |
12203 | @kindex remotetimeout | |
12204 | @value{GDBN} supports the option @code{remotetimeout}. | |
12205 | This option is set by the user, and @var{args} represents the number of | |
12206 | seconds @value{GDBN} waits for responses. | |
104c1213 JM |
12207 | @end table |
12208 | ||
8e04817f AC |
12209 | @cindex compiling, on Sparclet |
12210 | When compiling for debugging, include the options @samp{-g} to get debug | |
12211 | information and @samp{-Ttext} to relocate the program to where you wish to | |
12212 | load it on the target. You may also want to add the options @samp{-n} or | |
12213 | @samp{-N} in order to reduce the size of the sections. Example: | |
104c1213 | 12214 | |
474c8240 | 12215 | @smallexample |
8e04817f | 12216 | sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N |
474c8240 | 12217 | @end smallexample |
104c1213 | 12218 | |
8e04817f | 12219 | You can use @code{objdump} to verify that the addresses are what you intended: |
104c1213 | 12220 | |
474c8240 | 12221 | @smallexample |
8e04817f | 12222 | sparclet-aout-objdump --headers --syms prog |
474c8240 | 12223 | @end smallexample |
104c1213 | 12224 | |
8e04817f AC |
12225 | @cindex running, on Sparclet |
12226 | Once you have set | |
12227 | your Unix execution search path to find @value{GDBN}, you are ready to | |
12228 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} | |
12229 | (or @code{sparclet-aout-gdb}, depending on your installation). | |
104c1213 | 12230 | |
8e04817f AC |
12231 | @value{GDBN} comes up showing the prompt: |
12232 | ||
474c8240 | 12233 | @smallexample |
8e04817f | 12234 | (gdbslet) |
474c8240 | 12235 | @end smallexample |
104c1213 JM |
12236 | |
12237 | @menu | |
8e04817f AC |
12238 | * Sparclet File:: Setting the file to debug |
12239 | * Sparclet Connection:: Connecting to Sparclet | |
12240 | * Sparclet Download:: Sparclet download | |
12241 | * Sparclet Execution:: Running and debugging | |
104c1213 JM |
12242 | @end menu |
12243 | ||
8e04817f AC |
12244 | @node Sparclet File |
12245 | @subsubsection Setting file to debug | |
104c1213 | 12246 | |
8e04817f | 12247 | The @value{GDBN} command @code{file} lets you choose with program to debug. |
104c1213 | 12248 | |
474c8240 | 12249 | @smallexample |
8e04817f | 12250 | (gdbslet) file prog |
474c8240 | 12251 | @end smallexample |
104c1213 | 12252 | |
8e04817f AC |
12253 | @need 1000 |
12254 | @value{GDBN} then attempts to read the symbol table of @file{prog}. | |
12255 | @value{GDBN} locates | |
12256 | the file by searching the directories listed in the command search | |
12257 | path. | |
12258 | If the file was compiled with debug information (option "-g"), source | |
12259 | files will be searched as well. | |
12260 | @value{GDBN} locates | |
12261 | the source files by searching the directories listed in the directory search | |
12262 | path (@pxref{Environment, ,Your program's environment}). | |
12263 | If it fails | |
12264 | to find a file, it displays a message such as: | |
104c1213 | 12265 | |
474c8240 | 12266 | @smallexample |
8e04817f | 12267 | prog: No such file or directory. |
474c8240 | 12268 | @end smallexample |
104c1213 | 12269 | |
8e04817f AC |
12270 | When this happens, add the appropriate directories to the search paths with |
12271 | the @value{GDBN} commands @code{path} and @code{dir}, and execute the | |
12272 | @code{target} command again. | |
104c1213 | 12273 | |
8e04817f AC |
12274 | @node Sparclet Connection |
12275 | @subsubsection Connecting to Sparclet | |
104c1213 | 12276 | |
8e04817f AC |
12277 | The @value{GDBN} command @code{target} lets you connect to a Sparclet target. |
12278 | To connect to a target on serial port ``@code{ttya}'', type: | |
104c1213 | 12279 | |
474c8240 | 12280 | @smallexample |
8e04817f AC |
12281 | (gdbslet) target sparclet /dev/ttya |
12282 | Remote target sparclet connected to /dev/ttya | |
12283 | main () at ../prog.c:3 | |
474c8240 | 12284 | @end smallexample |
104c1213 | 12285 | |
8e04817f AC |
12286 | @need 750 |
12287 | @value{GDBN} displays messages like these: | |
104c1213 | 12288 | |
474c8240 | 12289 | @smallexample |
8e04817f | 12290 | Connected to ttya. |
474c8240 | 12291 | @end smallexample |
104c1213 | 12292 | |
8e04817f AC |
12293 | @node Sparclet Download |
12294 | @subsubsection Sparclet download | |
104c1213 | 12295 | |
8e04817f AC |
12296 | @cindex download to Sparclet |
12297 | Once connected to the Sparclet target, | |
12298 | you can use the @value{GDBN} | |
12299 | @code{load} command to download the file from the host to the target. | |
12300 | The file name and load offset should be given as arguments to the @code{load} | |
12301 | command. | |
12302 | Since the file format is aout, the program must be loaded to the starting | |
12303 | address. You can use @code{objdump} to find out what this value is. The load | |
12304 | offset is an offset which is added to the VMA (virtual memory address) | |
12305 | of each of the file's sections. | |
12306 | For instance, if the program | |
12307 | @file{prog} was linked to text address 0x1201000, with data at 0x12010160 | |
12308 | and bss at 0x12010170, in @value{GDBN}, type: | |
104c1213 | 12309 | |
474c8240 | 12310 | @smallexample |
8e04817f AC |
12311 | (gdbslet) load prog 0x12010000 |
12312 | Loading section .text, size 0xdb0 vma 0x12010000 | |
474c8240 | 12313 | @end smallexample |
104c1213 | 12314 | |
8e04817f AC |
12315 | If the code is loaded at a different address then what the program was linked |
12316 | to, you may need to use the @code{section} and @code{add-symbol-file} commands | |
12317 | to tell @value{GDBN} where to map the symbol table. | |
12318 | ||
12319 | @node Sparclet Execution | |
12320 | @subsubsection Running and debugging | |
12321 | ||
12322 | @cindex running and debugging Sparclet programs | |
12323 | You can now begin debugging the task using @value{GDBN}'s execution control | |
12324 | commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN} | |
12325 | manual for the list of commands. | |
12326 | ||
474c8240 | 12327 | @smallexample |
8e04817f AC |
12328 | (gdbslet) b main |
12329 | Breakpoint 1 at 0x12010000: file prog.c, line 3. | |
12330 | (gdbslet) run | |
12331 | Starting program: prog | |
12332 | Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3 | |
12333 | 3 char *symarg = 0; | |
12334 | (gdbslet) step | |
12335 | 4 char *execarg = "hello!"; | |
12336 | (gdbslet) | |
474c8240 | 12337 | @end smallexample |
8e04817f AC |
12338 | |
12339 | @node Sparclite | |
12340 | @subsection Fujitsu Sparclite | |
104c1213 JM |
12341 | |
12342 | @table @code | |
12343 | ||
8e04817f AC |
12344 | @kindex target sparclite |
12345 | @item target sparclite @var{dev} | |
12346 | Fujitsu sparclite boards, used only for the purpose of loading. | |
12347 | You must use an additional command to debug the program. | |
12348 | For example: target remote @var{dev} using @value{GDBN} standard | |
12349 | remote protocol. | |
104c1213 JM |
12350 | |
12351 | @end table | |
12352 | ||
8e04817f AC |
12353 | @node ST2000 |
12354 | @subsection Tandem ST2000 | |
104c1213 | 12355 | |
8e04817f AC |
12356 | @value{GDBN} may be used with a Tandem ST2000 phone switch, running Tandem's |
12357 | STDBUG protocol. | |
104c1213 | 12358 | |
8e04817f AC |
12359 | To connect your ST2000 to the host system, see the manufacturer's |
12360 | manual. Once the ST2000 is physically attached, you can run: | |
104c1213 | 12361 | |
474c8240 | 12362 | @smallexample |
8e04817f | 12363 | target st2000 @var{dev} @var{speed} |
474c8240 | 12364 | @end smallexample |
104c1213 | 12365 | |
8e04817f AC |
12366 | @noindent |
12367 | to establish it as your debugging environment. @var{dev} is normally | |
12368 | the name of a serial device, such as @file{/dev/ttya}, connected to the | |
12369 | ST2000 via a serial line. You can instead specify @var{dev} as a TCP | |
12370 | connection (for example, to a serial line attached via a terminal | |
12371 | concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}. | |
104c1213 | 12372 | |
8e04817f AC |
12373 | The @code{load} and @code{attach} commands are @emph{not} defined for |
12374 | this target; you must load your program into the ST2000 as you normally | |
12375 | would for standalone operation. @value{GDBN} reads debugging information | |
12376 | (such as symbols) from a separate, debugging version of the program | |
12377 | available on your host computer. | |
12378 | @c FIXME!! This is terribly vague; what little content is here is | |
12379 | @c basically hearsay. | |
104c1213 | 12380 | |
8e04817f AC |
12381 | @cindex ST2000 auxiliary commands |
12382 | These auxiliary @value{GDBN} commands are available to help you with the ST2000 | |
12383 | environment: | |
104c1213 | 12384 | |
8e04817f AC |
12385 | @table @code |
12386 | @item st2000 @var{command} | |
12387 | @kindex st2000 @var{cmd} | |
12388 | @cindex STDBUG commands (ST2000) | |
12389 | @cindex commands to STDBUG (ST2000) | |
12390 | Send a @var{command} to the STDBUG monitor. See the manufacturer's | |
12391 | manual for available commands. | |
104c1213 | 12392 | |
8e04817f AC |
12393 | @item connect |
12394 | @cindex connect (to STDBUG) | |
12395 | Connect the controlling terminal to the STDBUG command monitor. When | |
12396 | you are done interacting with STDBUG, typing either of two character | |
12397 | sequences gets you back to the @value{GDBN} command prompt: | |
12398 | @kbd{@key{RET}~.} (Return, followed by tilde and period) or | |
12399 | @kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D). | |
104c1213 JM |
12400 | @end table |
12401 | ||
8e04817f AC |
12402 | @node Z8000 |
12403 | @subsection Zilog Z8000 | |
104c1213 | 12404 | |
8e04817f AC |
12405 | @cindex Z8000 |
12406 | @cindex simulator, Z8000 | |
12407 | @cindex Zilog Z8000 simulator | |
104c1213 | 12408 | |
8e04817f AC |
12409 | When configured for debugging Zilog Z8000 targets, @value{GDBN} includes |
12410 | a Z8000 simulator. | |
12411 | ||
12412 | For the Z8000 family, @samp{target sim} simulates either the Z8002 (the | |
12413 | unsegmented variant of the Z8000 architecture) or the Z8001 (the | |
12414 | segmented variant). The simulator recognizes which architecture is | |
12415 | appropriate by inspecting the object code. | |
104c1213 | 12416 | |
8e04817f AC |
12417 | @table @code |
12418 | @item target sim @var{args} | |
12419 | @kindex sim | |
12420 | @kindex target sim@r{, with Z8000} | |
12421 | Debug programs on a simulated CPU. If the simulator supports setup | |
12422 | options, specify them via @var{args}. | |
104c1213 JM |
12423 | @end table |
12424 | ||
8e04817f AC |
12425 | @noindent |
12426 | After specifying this target, you can debug programs for the simulated | |
12427 | CPU in the same style as programs for your host computer; use the | |
12428 | @code{file} command to load a new program image, the @code{run} command | |
12429 | to run your program, and so on. | |
12430 | ||
12431 | As well as making available all the usual machine registers | |
12432 | (@pxref{Registers, ,Registers}), the Z8000 simulator provides three | |
12433 | additional items of information as specially named registers: | |
104c1213 JM |
12434 | |
12435 | @table @code | |
12436 | ||
8e04817f AC |
12437 | @item cycles |
12438 | Counts clock-ticks in the simulator. | |
104c1213 | 12439 | |
8e04817f AC |
12440 | @item insts |
12441 | Counts instructions run in the simulator. | |
104c1213 | 12442 | |
8e04817f AC |
12443 | @item time |
12444 | Execution time in 60ths of a second. | |
104c1213 | 12445 | |
8e04817f | 12446 | @end table |
104c1213 | 12447 | |
8e04817f AC |
12448 | You can refer to these values in @value{GDBN} expressions with the usual |
12449 | conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a | |
12450 | conditional breakpoint that suspends only after at least 5000 | |
12451 | simulated clock ticks. | |
104c1213 | 12452 | |
8e04817f AC |
12453 | @node Architectures |
12454 | @section Architectures | |
104c1213 | 12455 | |
8e04817f AC |
12456 | This section describes characteristics of architectures that affect |
12457 | all uses of @value{GDBN} with the architecture, both native and cross. | |
104c1213 | 12458 | |
8e04817f AC |
12459 | @menu |
12460 | * A29K:: | |
12461 | * Alpha:: | |
12462 | * MIPS:: | |
12463 | @end menu | |
104c1213 | 12464 | |
8e04817f AC |
12465 | @node A29K |
12466 | @subsection A29K | |
104c1213 JM |
12467 | |
12468 | @table @code | |
104c1213 | 12469 | |
8e04817f AC |
12470 | @kindex set rstack_high_address |
12471 | @cindex AMD 29K register stack | |
12472 | @cindex register stack, AMD29K | |
12473 | @item set rstack_high_address @var{address} | |
12474 | On AMD 29000 family processors, registers are saved in a separate | |
12475 | @dfn{register stack}. There is no way for @value{GDBN} to determine the | |
12476 | extent of this stack. Normally, @value{GDBN} just assumes that the | |
12477 | stack is ``large enough''. This may result in @value{GDBN} referencing | |
12478 | memory locations that do not exist. If necessary, you can get around | |
12479 | this problem by specifying the ending address of the register stack with | |
12480 | the @code{set rstack_high_address} command. The argument should be an | |
12481 | address, which you probably want to precede with @samp{0x} to specify in | |
12482 | hexadecimal. | |
104c1213 | 12483 | |
8e04817f AC |
12484 | @kindex show rstack_high_address |
12485 | @item show rstack_high_address | |
12486 | Display the current limit of the register stack, on AMD 29000 family | |
12487 | processors. | |
104c1213 | 12488 | |
8e04817f | 12489 | @end table |
104c1213 | 12490 | |
8e04817f AC |
12491 | @node Alpha |
12492 | @subsection Alpha | |
104c1213 | 12493 | |
8e04817f | 12494 | See the following section. |
104c1213 | 12495 | |
8e04817f AC |
12496 | @node MIPS |
12497 | @subsection MIPS | |
104c1213 | 12498 | |
8e04817f AC |
12499 | @cindex stack on Alpha |
12500 | @cindex stack on MIPS | |
12501 | @cindex Alpha stack | |
12502 | @cindex MIPS stack | |
12503 | Alpha- and MIPS-based computers use an unusual stack frame, which | |
12504 | sometimes requires @value{GDBN} to search backward in the object code to | |
12505 | find the beginning of a function. | |
104c1213 | 12506 | |
8e04817f AC |
12507 | @cindex response time, MIPS debugging |
12508 | To improve response time (especially for embedded applications, where | |
12509 | @value{GDBN} may be restricted to a slow serial line for this search) | |
12510 | you may want to limit the size of this search, using one of these | |
12511 | commands: | |
104c1213 | 12512 | |
8e04817f AC |
12513 | @table @code |
12514 | @cindex @code{heuristic-fence-post} (Alpha, MIPS) | |
12515 | @item set heuristic-fence-post @var{limit} | |
12516 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its | |
12517 | search for the beginning of a function. A value of @var{0} (the | |
12518 | default) means there is no limit. However, except for @var{0}, the | |
12519 | larger the limit the more bytes @code{heuristic-fence-post} must search | |
12520 | and therefore the longer it takes to run. | |
104c1213 | 12521 | |
8e04817f AC |
12522 | @item show heuristic-fence-post |
12523 | Display the current limit. | |
12524 | @end table | |
104c1213 JM |
12525 | |
12526 | @noindent | |
8e04817f AC |
12527 | These commands are available @emph{only} when @value{GDBN} is configured |
12528 | for debugging programs on Alpha or MIPS processors. | |
104c1213 | 12529 | |
104c1213 | 12530 | |
8e04817f AC |
12531 | @node Controlling GDB |
12532 | @chapter Controlling @value{GDBN} | |
12533 | ||
12534 | You can alter the way @value{GDBN} interacts with you by using the | |
12535 | @code{set} command. For commands controlling how @value{GDBN} displays | |
12536 | data, see @ref{Print Settings, ,Print settings}. Other settings are | |
12537 | described here. | |
12538 | ||
12539 | @menu | |
12540 | * Prompt:: Prompt | |
12541 | * Editing:: Command editing | |
12542 | * History:: Command history | |
12543 | * Screen Size:: Screen size | |
12544 | * Numbers:: Numbers | |
1e698235 | 12545 | * ABI:: Configuring the current ABI |
8e04817f AC |
12546 | * Messages/Warnings:: Optional warnings and messages |
12547 | * Debugging Output:: Optional messages about internal happenings | |
12548 | @end menu | |
12549 | ||
12550 | @node Prompt | |
12551 | @section Prompt | |
104c1213 | 12552 | |
8e04817f | 12553 | @cindex prompt |
104c1213 | 12554 | |
8e04817f AC |
12555 | @value{GDBN} indicates its readiness to read a command by printing a string |
12556 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You | |
12557 | can change the prompt string with the @code{set prompt} command. For | |
12558 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change | |
12559 | the prompt in one of the @value{GDBN} sessions so that you can always tell | |
12560 | which one you are talking to. | |
104c1213 | 12561 | |
8e04817f AC |
12562 | @emph{Note:} @code{set prompt} does not add a space for you after the |
12563 | prompt you set. This allows you to set a prompt which ends in a space | |
12564 | or a prompt that does not. | |
104c1213 | 12565 | |
8e04817f AC |
12566 | @table @code |
12567 | @kindex set prompt | |
12568 | @item set prompt @var{newprompt} | |
12569 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. | |
104c1213 | 12570 | |
8e04817f AC |
12571 | @kindex show prompt |
12572 | @item show prompt | |
12573 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} | |
104c1213 JM |
12574 | @end table |
12575 | ||
8e04817f AC |
12576 | @node Editing |
12577 | @section Command editing | |
12578 | @cindex readline | |
12579 | @cindex command line editing | |
104c1213 | 12580 | |
8e04817f AC |
12581 | @value{GDBN} reads its input commands via the @dfn{readline} interface. This |
12582 | @sc{gnu} library provides consistent behavior for programs which provide a | |
12583 | command line interface to the user. Advantages are @sc{gnu} Emacs-style | |
12584 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history | |
12585 | substitution, and a storage and recall of command history across | |
12586 | debugging sessions. | |
104c1213 | 12587 | |
8e04817f AC |
12588 | You may control the behavior of command line editing in @value{GDBN} with the |
12589 | command @code{set}. | |
104c1213 | 12590 | |
8e04817f AC |
12591 | @table @code |
12592 | @kindex set editing | |
12593 | @cindex editing | |
12594 | @item set editing | |
12595 | @itemx set editing on | |
12596 | Enable command line editing (enabled by default). | |
104c1213 | 12597 | |
8e04817f AC |
12598 | @item set editing off |
12599 | Disable command line editing. | |
104c1213 | 12600 | |
8e04817f AC |
12601 | @kindex show editing |
12602 | @item show editing | |
12603 | Show whether command line editing is enabled. | |
104c1213 JM |
12604 | @end table |
12605 | ||
8e04817f AC |
12606 | @node History |
12607 | @section Command history | |
12608 | ||
12609 | @value{GDBN} can keep track of the commands you type during your | |
12610 | debugging sessions, so that you can be certain of precisely what | |
12611 | happened. Use these commands to manage the @value{GDBN} command | |
12612 | history facility. | |
104c1213 JM |
12613 | |
12614 | @table @code | |
8e04817f AC |
12615 | @cindex history substitution |
12616 | @cindex history file | |
12617 | @kindex set history filename | |
12618 | @kindex GDBHISTFILE | |
12619 | @item set history filename @var{fname} | |
12620 | Set the name of the @value{GDBN} command history file to @var{fname}. | |
12621 | This is the file where @value{GDBN} reads an initial command history | |
12622 | list, and where it writes the command history from this session when it | |
12623 | exits. You can access this list through history expansion or through | |
12624 | the history command editing characters listed below. This file defaults | |
12625 | to the value of the environment variable @code{GDBHISTFILE}, or to | |
12626 | @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable | |
12627 | is not set. | |
104c1213 | 12628 | |
8e04817f AC |
12629 | @cindex history save |
12630 | @kindex set history save | |
12631 | @item set history save | |
12632 | @itemx set history save on | |
12633 | Record command history in a file, whose name may be specified with the | |
12634 | @code{set history filename} command. By default, this option is disabled. | |
104c1213 | 12635 | |
8e04817f AC |
12636 | @item set history save off |
12637 | Stop recording command history in a file. | |
104c1213 | 12638 | |
8e04817f AC |
12639 | @cindex history size |
12640 | @kindex set history size | |
12641 | @item set history size @var{size} | |
12642 | Set the number of commands which @value{GDBN} keeps in its history list. | |
12643 | This defaults to the value of the environment variable | |
12644 | @code{HISTSIZE}, or to 256 if this variable is not set. | |
104c1213 JM |
12645 | @end table |
12646 | ||
8e04817f AC |
12647 | @cindex history expansion |
12648 | History expansion assigns special meaning to the character @kbd{!}. | |
12649 | @ifset have-readline-appendices | |
12650 | @xref{Event Designators}. | |
12651 | @end ifset | |
12652 | ||
12653 | Since @kbd{!} is also the logical not operator in C, history expansion | |
12654 | is off by default. If you decide to enable history expansion with the | |
12655 | @code{set history expansion on} command, you may sometimes need to | |
12656 | follow @kbd{!} (when it is used as logical not, in an expression) with | |
12657 | a space or a tab to prevent it from being expanded. The readline | |
12658 | history facilities do not attempt substitution on the strings | |
12659 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. | |
12660 | ||
12661 | The commands to control history expansion are: | |
104c1213 JM |
12662 | |
12663 | @table @code | |
8e04817f AC |
12664 | @kindex set history expansion |
12665 | @item set history expansion on | |
12666 | @itemx set history expansion | |
12667 | Enable history expansion. History expansion is off by default. | |
104c1213 | 12668 | |
8e04817f AC |
12669 | @item set history expansion off |
12670 | Disable history expansion. | |
104c1213 | 12671 | |
8e04817f AC |
12672 | The readline code comes with more complete documentation of |
12673 | editing and history expansion features. Users unfamiliar with @sc{gnu} Emacs | |
12674 | or @code{vi} may wish to read it. | |
12675 | @ifset have-readline-appendices | |
12676 | @xref{Command Line Editing}. | |
12677 | @end ifset | |
104c1213 | 12678 | |
8e04817f AC |
12679 | @c @group |
12680 | @kindex show history | |
12681 | @item show history | |
12682 | @itemx show history filename | |
12683 | @itemx show history save | |
12684 | @itemx show history size | |
12685 | @itemx show history expansion | |
12686 | These commands display the state of the @value{GDBN} history parameters. | |
12687 | @code{show history} by itself displays all four states. | |
12688 | @c @end group | |
12689 | @end table | |
12690 | ||
12691 | @table @code | |
12692 | @kindex shows | |
12693 | @item show commands | |
12694 | Display the last ten commands in the command history. | |
104c1213 | 12695 | |
8e04817f AC |
12696 | @item show commands @var{n} |
12697 | Print ten commands centered on command number @var{n}. | |
12698 | ||
12699 | @item show commands + | |
12700 | Print ten commands just after the commands last printed. | |
104c1213 JM |
12701 | @end table |
12702 | ||
8e04817f AC |
12703 | @node Screen Size |
12704 | @section Screen size | |
12705 | @cindex size of screen | |
12706 | @cindex pauses in output | |
104c1213 | 12707 | |
8e04817f AC |
12708 | Certain commands to @value{GDBN} may produce large amounts of |
12709 | information output to the screen. To help you read all of it, | |
12710 | @value{GDBN} pauses and asks you for input at the end of each page of | |
12711 | output. Type @key{RET} when you want to continue the output, or @kbd{q} | |
12712 | to discard the remaining output. Also, the screen width setting | |
12713 | determines when to wrap lines of output. Depending on what is being | |
12714 | printed, @value{GDBN} tries to break the line at a readable place, | |
12715 | rather than simply letting it overflow onto the following line. | |
12716 | ||
12717 | Normally @value{GDBN} knows the size of the screen from the terminal | |
12718 | driver software. For example, on Unix @value{GDBN} uses the termcap data base | |
12719 | together with the value of the @code{TERM} environment variable and the | |
12720 | @code{stty rows} and @code{stty cols} settings. If this is not correct, | |
12721 | you can override it with the @code{set height} and @code{set | |
12722 | width} commands: | |
12723 | ||
12724 | @table @code | |
12725 | @kindex set height | |
12726 | @kindex set width | |
12727 | @kindex show width | |
12728 | @kindex show height | |
12729 | @item set height @var{lpp} | |
12730 | @itemx show height | |
12731 | @itemx set width @var{cpl} | |
12732 | @itemx show width | |
12733 | These @code{set} commands specify a screen height of @var{lpp} lines and | |
12734 | a screen width of @var{cpl} characters. The associated @code{show} | |
12735 | commands display the current settings. | |
104c1213 | 12736 | |
8e04817f AC |
12737 | If you specify a height of zero lines, @value{GDBN} does not pause during |
12738 | output no matter how long the output is. This is useful if output is to a | |
12739 | file or to an editor buffer. | |
104c1213 | 12740 | |
8e04817f AC |
12741 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} |
12742 | from wrapping its output. | |
104c1213 JM |
12743 | @end table |
12744 | ||
8e04817f AC |
12745 | @node Numbers |
12746 | @section Numbers | |
12747 | @cindex number representation | |
12748 | @cindex entering numbers | |
104c1213 | 12749 | |
8e04817f AC |
12750 | You can always enter numbers in octal, decimal, or hexadecimal in |
12751 | @value{GDBN} by the usual conventions: octal numbers begin with | |
12752 | @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers | |
12753 | begin with @samp{0x}. Numbers that begin with none of these are, by | |
12754 | default, entered in base 10; likewise, the default display for | |
12755 | numbers---when no particular format is specified---is base 10. You can | |
12756 | change the default base for both input and output with the @code{set | |
12757 | radix} command. | |
104c1213 | 12758 | |
8e04817f AC |
12759 | @table @code |
12760 | @kindex set input-radix | |
12761 | @item set input-radix @var{base} | |
12762 | Set the default base for numeric input. Supported choices | |
12763 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
12764 | specified either unambiguously or using the current default radix; for | |
12765 | example, any of | |
104c1213 | 12766 | |
8e04817f AC |
12767 | @smallexample |
12768 | set radix 012 | |
12769 | set radix 10. | |
12770 | set radix 0xa | |
12771 | @end smallexample | |
104c1213 | 12772 | |
8e04817f AC |
12773 | @noindent |
12774 | sets the base to decimal. On the other hand, @samp{set radix 10} | |
12775 | leaves the radix unchanged no matter what it was. | |
104c1213 | 12776 | |
8e04817f AC |
12777 | @kindex set output-radix |
12778 | @item set output-radix @var{base} | |
12779 | Set the default base for numeric display. Supported choices | |
12780 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
12781 | specified either unambiguously or using the current default radix. | |
104c1213 | 12782 | |
8e04817f AC |
12783 | @kindex show input-radix |
12784 | @item show input-radix | |
12785 | Display the current default base for numeric input. | |
104c1213 | 12786 | |
8e04817f AC |
12787 | @kindex show output-radix |
12788 | @item show output-radix | |
12789 | Display the current default base for numeric display. | |
12790 | @end table | |
104c1213 | 12791 | |
1e698235 DJ |
12792 | @node ABI |
12793 | @section Configuring the current ABI | |
12794 | ||
12795 | @value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your | |
12796 | application automatically. However, sometimes you need to override its | |
12797 | conclusions. Use these commands to manage @value{GDBN}'s view of the | |
12798 | current ABI. | |
12799 | ||
98b45e30 DJ |
12800 | @cindex OS ABI |
12801 | @kindex set osabi | |
b4e9345d | 12802 | @kindex show osabi |
98b45e30 DJ |
12803 | |
12804 | One @value{GDBN} configuration can debug binaries for multiple operating | |
12805 | system targets, either via remote debugging or native emulation. | |
12806 | @value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use, | |
12807 | but you can override its conclusion using the @code{set osabi} command. | |
12808 | One example where this is useful is in debugging of binaries which use | |
12809 | an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does | |
12810 | not have the same identifying marks that the standard C library for your | |
12811 | platform provides. | |
12812 | ||
12813 | @table @code | |
12814 | @item show osabi | |
12815 | Show the OS ABI currently in use. | |
12816 | ||
12817 | @item set osabi | |
12818 | With no argument, show the list of registered available OS ABI's. | |
12819 | ||
12820 | @item set osabi @var{abi} | |
12821 | Set the current OS ABI to @var{abi}. | |
12822 | @end table | |
12823 | ||
1e698235 DJ |
12824 | @cindex float promotion |
12825 | @kindex set coerce-float-to-double | |
12826 | ||
12827 | Generally, the way that an argument of type @code{float} is passed to a | |
12828 | function depends on whether the function is prototyped. For a prototyped | |
12829 | (i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged, | |
12830 | according to the architecture's convention for @code{float}. For unprototyped | |
12831 | (i.e.@: K&R style) functions, @code{float} arguments are first promoted to type | |
12832 | @code{double} and then passed. | |
12833 | ||
12834 | Unfortunately, some forms of debug information do not reliably indicate whether | |
12835 | a function is prototyped. If @value{GDBN} calls a function that is not marked | |
12836 | as prototyped, it consults @kbd{set coerce-float-to-double}. | |
12837 | ||
12838 | @table @code | |
12839 | @item set coerce-float-to-double | |
12840 | @itemx set coerce-float-to-double on | |
12841 | Arguments of type @code{float} will be promoted to @code{double} when passed | |
12842 | to an unprototyped function. This is the default setting. | |
12843 | ||
12844 | @item set coerce-float-to-double off | |
12845 | Arguments of type @code{float} will be passed directly to unprototyped | |
12846 | functions. | |
12847 | @end table | |
12848 | ||
f1212245 DJ |
12849 | @kindex set cp-abi |
12850 | @kindex show cp-abi | |
12851 | @value{GDBN} needs to know the ABI used for your program's C@t{++} | |
12852 | objects. The correct C@t{++} ABI depends on which C@t{++} compiler was | |
12853 | used to build your application. @value{GDBN} only fully supports | |
12854 | programs with a single C@t{++} ABI; if your program contains code using | |
12855 | multiple C@t{++} ABI's or if @value{GDBN} can not identify your | |
12856 | program's ABI correctly, you can tell @value{GDBN} which ABI to use. | |
12857 | Currently supported ABI's include ``gnu-v2'', for @code{g++} versions | |
12858 | before 3.0, ``gnu-v3'', for @code{g++} versions 3.0 and later, and | |
12859 | ``hpaCC'' for the HP ANSI C@t{++} compiler. Other C@t{++} compilers may | |
12860 | use the ``gnu-v2'' or ``gnu-v3'' ABI's as well. The default setting is | |
12861 | ``auto''. | |
12862 | ||
12863 | @table @code | |
12864 | @item show cp-abi | |
12865 | Show the C@t{++} ABI currently in use. | |
12866 | ||
12867 | @item set cp-abi | |
12868 | With no argument, show the list of supported C@t{++} ABI's. | |
12869 | ||
12870 | @item set cp-abi @var{abi} | |
12871 | @itemx set cp-abi auto | |
12872 | Set the current C@t{++} ABI to @var{abi}, or return to automatic detection. | |
12873 | @end table | |
12874 | ||
8e04817f AC |
12875 | @node Messages/Warnings |
12876 | @section Optional warnings and messages | |
104c1213 | 12877 | |
8e04817f AC |
12878 | By default, @value{GDBN} is silent about its inner workings. If you are |
12879 | running on a slow machine, you may want to use the @code{set verbose} | |
12880 | command. This makes @value{GDBN} tell you when it does a lengthy | |
12881 | internal operation, so you will not think it has crashed. | |
104c1213 | 12882 | |
8e04817f AC |
12883 | Currently, the messages controlled by @code{set verbose} are those |
12884 | which announce that the symbol table for a source file is being read; | |
12885 | see @code{symbol-file} in @ref{Files, ,Commands to specify files}. | |
104c1213 | 12886 | |
8e04817f AC |
12887 | @table @code |
12888 | @kindex set verbose | |
12889 | @item set verbose on | |
12890 | Enables @value{GDBN} output of certain informational messages. | |
104c1213 | 12891 | |
8e04817f AC |
12892 | @item set verbose off |
12893 | Disables @value{GDBN} output of certain informational messages. | |
104c1213 | 12894 | |
8e04817f AC |
12895 | @kindex show verbose |
12896 | @item show verbose | |
12897 | Displays whether @code{set verbose} is on or off. | |
12898 | @end table | |
104c1213 | 12899 | |
8e04817f AC |
12900 | By default, if @value{GDBN} encounters bugs in the symbol table of an |
12901 | object file, it is silent; but if you are debugging a compiler, you may | |
12902 | find this information useful (@pxref{Symbol Errors, ,Errors reading | |
12903 | symbol files}). | |
104c1213 | 12904 | |
8e04817f | 12905 | @table @code |
104c1213 | 12906 | |
8e04817f AC |
12907 | @kindex set complaints |
12908 | @item set complaints @var{limit} | |
12909 | Permits @value{GDBN} to output @var{limit} complaints about each type of | |
12910 | unusual symbols before becoming silent about the problem. Set | |
12911 | @var{limit} to zero to suppress all complaints; set it to a large number | |
12912 | to prevent complaints from being suppressed. | |
104c1213 | 12913 | |
8e04817f AC |
12914 | @kindex show complaints |
12915 | @item show complaints | |
12916 | Displays how many symbol complaints @value{GDBN} is permitted to produce. | |
104c1213 | 12917 | |
8e04817f | 12918 | @end table |
104c1213 | 12919 | |
8e04817f AC |
12920 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a |
12921 | lot of stupid questions to confirm certain commands. For example, if | |
12922 | you try to run a program which is already running: | |
104c1213 | 12923 | |
474c8240 | 12924 | @smallexample |
8e04817f AC |
12925 | (@value{GDBP}) run |
12926 | The program being debugged has been started already. | |
12927 | Start it from the beginning? (y or n) | |
474c8240 | 12928 | @end smallexample |
104c1213 | 12929 | |
8e04817f AC |
12930 | If you are willing to unflinchingly face the consequences of your own |
12931 | commands, you can disable this ``feature'': | |
104c1213 | 12932 | |
8e04817f | 12933 | @table @code |
104c1213 | 12934 | |
8e04817f AC |
12935 | @kindex set confirm |
12936 | @cindex flinching | |
12937 | @cindex confirmation | |
12938 | @cindex stupid questions | |
12939 | @item set confirm off | |
12940 | Disables confirmation requests. | |
104c1213 | 12941 | |
8e04817f AC |
12942 | @item set confirm on |
12943 | Enables confirmation requests (the default). | |
104c1213 | 12944 | |
8e04817f AC |
12945 | @kindex show confirm |
12946 | @item show confirm | |
12947 | Displays state of confirmation requests. | |
12948 | ||
12949 | @end table | |
104c1213 | 12950 | |
8e04817f AC |
12951 | @node Debugging Output |
12952 | @section Optional messages about internal happenings | |
104c1213 | 12953 | @table @code |
8e04817f AC |
12954 | @kindex set debug arch |
12955 | @item set debug arch | |
12956 | Turns on or off display of gdbarch debugging info. The default is off | |
12957 | @kindex show debug arch | |
12958 | @item show debug arch | |
12959 | Displays the current state of displaying gdbarch debugging info. | |
12960 | @kindex set debug event | |
12961 | @item set debug event | |
12962 | Turns on or off display of @value{GDBN} event debugging info. The | |
12963 | default is off. | |
12964 | @kindex show debug event | |
12965 | @item show debug event | |
12966 | Displays the current state of displaying @value{GDBN} event debugging | |
12967 | info. | |
12968 | @kindex set debug expression | |
12969 | @item set debug expression | |
12970 | Turns on or off display of @value{GDBN} expression debugging info. The | |
12971 | default is off. | |
12972 | @kindex show debug expression | |
12973 | @item show debug expression | |
12974 | Displays the current state of displaying @value{GDBN} expression | |
12975 | debugging info. | |
12976 | @kindex set debug overload | |
12977 | @item set debug overload | |
12978 | Turns on or off display of @value{GDBN} C@t{++} overload debugging | |
12979 | info. This includes info such as ranking of functions, etc. The default | |
12980 | is off. | |
12981 | @kindex show debug overload | |
12982 | @item show debug overload | |
12983 | Displays the current state of displaying @value{GDBN} C@t{++} overload | |
12984 | debugging info. | |
12985 | @kindex set debug remote | |
12986 | @cindex packets, reporting on stdout | |
12987 | @cindex serial connections, debugging | |
12988 | @item set debug remote | |
12989 | Turns on or off display of reports on all packets sent back and forth across | |
12990 | the serial line to the remote machine. The info is printed on the | |
12991 | @value{GDBN} standard output stream. The default is off. | |
12992 | @kindex show debug remote | |
12993 | @item show debug remote | |
12994 | Displays the state of display of remote packets. | |
12995 | @kindex set debug serial | |
12996 | @item set debug serial | |
12997 | Turns on or off display of @value{GDBN} serial debugging info. The | |
12998 | default is off. | |
12999 | @kindex show debug serial | |
13000 | @item show debug serial | |
13001 | Displays the current state of displaying @value{GDBN} serial debugging | |
13002 | info. | |
13003 | @kindex set debug target | |
13004 | @item set debug target | |
13005 | Turns on or off display of @value{GDBN} target debugging info. This info | |
13006 | includes what is going on at the target level of GDB, as it happens. The | |
13007 | default is off. | |
13008 | @kindex show debug target | |
13009 | @item show debug target | |
13010 | Displays the current state of displaying @value{GDBN} target debugging | |
13011 | info. | |
13012 | @kindex set debug varobj | |
13013 | @item set debug varobj | |
13014 | Turns on or off display of @value{GDBN} variable object debugging | |
13015 | info. The default is off. | |
13016 | @kindex show debug varobj | |
13017 | @item show debug varobj | |
13018 | Displays the current state of displaying @value{GDBN} variable object | |
13019 | debugging info. | |
13020 | @end table | |
104c1213 | 13021 | |
8e04817f AC |
13022 | @node Sequences |
13023 | @chapter Canned Sequences of Commands | |
104c1213 | 13024 | |
8e04817f AC |
13025 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint |
13026 | command lists}), @value{GDBN} provides two ways to store sequences of | |
13027 | commands for execution as a unit: user-defined commands and command | |
13028 | files. | |
104c1213 | 13029 | |
8e04817f AC |
13030 | @menu |
13031 | * Define:: User-defined commands | |
13032 | * Hooks:: User-defined command hooks | |
13033 | * Command Files:: Command files | |
13034 | * Output:: Commands for controlled output | |
13035 | @end menu | |
104c1213 | 13036 | |
8e04817f AC |
13037 | @node Define |
13038 | @section User-defined commands | |
104c1213 | 13039 | |
8e04817f AC |
13040 | @cindex user-defined command |
13041 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to | |
13042 | which you assign a new name as a command. This is done with the | |
13043 | @code{define} command. User commands may accept up to 10 arguments | |
13044 | separated by whitespace. Arguments are accessed within the user command | |
13045 | via @var{$arg0@dots{}$arg9}. A trivial example: | |
104c1213 | 13046 | |
8e04817f AC |
13047 | @smallexample |
13048 | define adder | |
13049 | print $arg0 + $arg1 + $arg2 | |
13050 | @end smallexample | |
104c1213 JM |
13051 | |
13052 | @noindent | |
8e04817f | 13053 | To execute the command use: |
104c1213 | 13054 | |
8e04817f AC |
13055 | @smallexample |
13056 | adder 1 2 3 | |
13057 | @end smallexample | |
104c1213 | 13058 | |
8e04817f AC |
13059 | @noindent |
13060 | This defines the command @code{adder}, which prints the sum of | |
13061 | its three arguments. Note the arguments are text substitutions, so they may | |
13062 | reference variables, use complex expressions, or even perform inferior | |
13063 | functions calls. | |
104c1213 JM |
13064 | |
13065 | @table @code | |
104c1213 | 13066 | |
8e04817f AC |
13067 | @kindex define |
13068 | @item define @var{commandname} | |
13069 | Define a command named @var{commandname}. If there is already a command | |
13070 | by that name, you are asked to confirm that you want to redefine it. | |
104c1213 | 13071 | |
8e04817f AC |
13072 | The definition of the command is made up of other @value{GDBN} command lines, |
13073 | which are given following the @code{define} command. The end of these | |
13074 | commands is marked by a line containing @code{end}. | |
104c1213 | 13075 | |
8e04817f AC |
13076 | @kindex if |
13077 | @kindex else | |
13078 | @item if | |
13079 | Takes a single argument, which is an expression to evaluate. | |
13080 | It is followed by a series of commands that are executed | |
13081 | only if the expression is true (nonzero). | |
13082 | There can then optionally be a line @code{else}, followed | |
13083 | by a series of commands that are only executed if the expression | |
13084 | was false. The end of the list is marked by a line containing @code{end}. | |
104c1213 | 13085 | |
8e04817f AC |
13086 | @kindex while |
13087 | @item while | |
13088 | The syntax is similar to @code{if}: the command takes a single argument, | |
13089 | which is an expression to evaluate, and must be followed by the commands to | |
13090 | execute, one per line, terminated by an @code{end}. | |
13091 | The commands are executed repeatedly as long as the expression | |
13092 | evaluates to true. | |
104c1213 | 13093 | |
8e04817f AC |
13094 | @kindex document |
13095 | @item document @var{commandname} | |
13096 | Document the user-defined command @var{commandname}, so that it can be | |
13097 | accessed by @code{help}. The command @var{commandname} must already be | |
13098 | defined. This command reads lines of documentation just as @code{define} | |
13099 | reads the lines of the command definition, ending with @code{end}. | |
13100 | After the @code{document} command is finished, @code{help} on command | |
13101 | @var{commandname} displays the documentation you have written. | |
104c1213 | 13102 | |
8e04817f AC |
13103 | You may use the @code{document} command again to change the |
13104 | documentation of a command. Redefining the command with @code{define} | |
13105 | does not change the documentation. | |
104c1213 | 13106 | |
8e04817f AC |
13107 | @kindex help user-defined |
13108 | @item help user-defined | |
13109 | List all user-defined commands, with the first line of the documentation | |
13110 | (if any) for each. | |
104c1213 | 13111 | |
8e04817f AC |
13112 | @kindex show user |
13113 | @item show user | |
13114 | @itemx show user @var{commandname} | |
13115 | Display the @value{GDBN} commands used to define @var{commandname} (but | |
13116 | not its documentation). If no @var{commandname} is given, display the | |
13117 | definitions for all user-defined commands. | |
104c1213 | 13118 | |
20f01a46 DH |
13119 | @kindex show max-user-call-depth |
13120 | @kindex set max-user-call-depth | |
13121 | @item show max-user-call-depth | |
5ca0cb28 DH |
13122 | @itemx set max-user-call-depth |
13123 | The value of @code{max-user-call-depth} controls how many recursion | |
13124 | levels are allowed in user-defined commands before GDB suspects an | |
13125 | infinite recursion and aborts the command. | |
20f01a46 | 13126 | |
104c1213 JM |
13127 | @end table |
13128 | ||
8e04817f AC |
13129 | When user-defined commands are executed, the |
13130 | commands of the definition are not printed. An error in any command | |
13131 | stops execution of the user-defined command. | |
104c1213 | 13132 | |
8e04817f AC |
13133 | If used interactively, commands that would ask for confirmation proceed |
13134 | without asking when used inside a user-defined command. Many @value{GDBN} | |
13135 | commands that normally print messages to say what they are doing omit the | |
13136 | messages when used in a user-defined command. | |
104c1213 | 13137 | |
8e04817f AC |
13138 | @node Hooks |
13139 | @section User-defined command hooks | |
13140 | @cindex command hooks | |
13141 | @cindex hooks, for commands | |
13142 | @cindex hooks, pre-command | |
104c1213 | 13143 | |
8e04817f AC |
13144 | @kindex hook |
13145 | @kindex hook- | |
13146 | You may define @dfn{hooks}, which are a special kind of user-defined | |
13147 | command. Whenever you run the command @samp{foo}, if the user-defined | |
13148 | command @samp{hook-foo} exists, it is executed (with no arguments) | |
13149 | before that command. | |
104c1213 | 13150 | |
8e04817f AC |
13151 | @cindex hooks, post-command |
13152 | @kindex hookpost | |
13153 | @kindex hookpost- | |
13154 | A hook may also be defined which is run after the command you executed. | |
13155 | Whenever you run the command @samp{foo}, if the user-defined command | |
13156 | @samp{hookpost-foo} exists, it is executed (with no arguments) after | |
13157 | that command. Post-execution hooks may exist simultaneously with | |
13158 | pre-execution hooks, for the same command. | |
104c1213 | 13159 | |
8e04817f AC |
13160 | It is valid for a hook to call the command which it hooks. If this |
13161 | occurs, the hook is not re-executed, thereby avoiding infinte recursion. | |
104c1213 | 13162 | |
8e04817f AC |
13163 | @c It would be nice if hookpost could be passed a parameter indicating |
13164 | @c if the command it hooks executed properly or not. FIXME! | |
104c1213 | 13165 | |
8e04817f AC |
13166 | @kindex stop@r{, a pseudo-command} |
13167 | In addition, a pseudo-command, @samp{stop} exists. Defining | |
13168 | (@samp{hook-stop}) makes the associated commands execute every time | |
13169 | execution stops in your program: before breakpoint commands are run, | |
13170 | displays are printed, or the stack frame is printed. | |
104c1213 | 13171 | |
8e04817f AC |
13172 | For example, to ignore @code{SIGALRM} signals while |
13173 | single-stepping, but treat them normally during normal execution, | |
13174 | you could define: | |
104c1213 | 13175 | |
474c8240 | 13176 | @smallexample |
8e04817f AC |
13177 | define hook-stop |
13178 | handle SIGALRM nopass | |
13179 | end | |
104c1213 | 13180 | |
8e04817f AC |
13181 | define hook-run |
13182 | handle SIGALRM pass | |
13183 | end | |
104c1213 | 13184 | |
8e04817f AC |
13185 | define hook-continue |
13186 | handle SIGLARM pass | |
13187 | end | |
474c8240 | 13188 | @end smallexample |
104c1213 | 13189 | |
8e04817f AC |
13190 | As a further example, to hook at the begining and end of the @code{echo} |
13191 | command, and to add extra text to the beginning and end of the message, | |
13192 | you could define: | |
104c1213 | 13193 | |
474c8240 | 13194 | @smallexample |
8e04817f AC |
13195 | define hook-echo |
13196 | echo <<<--- | |
13197 | end | |
104c1213 | 13198 | |
8e04817f AC |
13199 | define hookpost-echo |
13200 | echo --->>>\n | |
13201 | end | |
104c1213 | 13202 | |
8e04817f AC |
13203 | (@value{GDBP}) echo Hello World |
13204 | <<<---Hello World--->>> | |
13205 | (@value{GDBP}) | |
104c1213 | 13206 | |
474c8240 | 13207 | @end smallexample |
104c1213 | 13208 | |
8e04817f AC |
13209 | You can define a hook for any single-word command in @value{GDBN}, but |
13210 | not for command aliases; you should define a hook for the basic command | |
13211 | name, e.g. @code{backtrace} rather than @code{bt}. | |
13212 | @c FIXME! So how does Joe User discover whether a command is an alias | |
13213 | @c or not? | |
13214 | If an error occurs during the execution of your hook, execution of | |
13215 | @value{GDBN} commands stops and @value{GDBN} issues a prompt | |
13216 | (before the command that you actually typed had a chance to run). | |
104c1213 | 13217 | |
8e04817f AC |
13218 | If you try to define a hook which does not match any known command, you |
13219 | get a warning from the @code{define} command. | |
c906108c | 13220 | |
8e04817f AC |
13221 | @node Command Files |
13222 | @section Command files | |
c906108c | 13223 | |
8e04817f AC |
13224 | @cindex command files |
13225 | A command file for @value{GDBN} is a file of lines that are @value{GDBN} | |
13226 | commands. Comments (lines starting with @kbd{#}) may also be included. | |
13227 | An empty line in a command file does nothing; it does not mean to repeat | |
13228 | the last command, as it would from the terminal. | |
c906108c | 13229 | |
8e04817f AC |
13230 | @cindex init file |
13231 | @cindex @file{.gdbinit} | |
13232 | @cindex @file{gdb.ini} | |
13233 | When you start @value{GDBN}, it automatically executes commands from its | |
13234 | @dfn{init files}, normally called @file{.gdbinit}@footnote{The DJGPP | |
13235 | port of @value{GDBN} uses the name @file{gdb.ini} instead, due to the | |
13236 | limitations of file names imposed by DOS filesystems.}. | |
13237 | During startup, @value{GDBN} does the following: | |
c906108c | 13238 | |
8e04817f AC |
13239 | @enumerate |
13240 | @item | |
13241 | Reads the init file (if any) in your home directory@footnote{On | |
13242 | DOS/Windows systems, the home directory is the one pointed to by the | |
13243 | @code{HOME} environment variable.}. | |
c906108c | 13244 | |
8e04817f AC |
13245 | @item |
13246 | Processes command line options and operands. | |
c906108c | 13247 | |
8e04817f AC |
13248 | @item |
13249 | Reads the init file (if any) in the current working directory. | |
c906108c | 13250 | |
8e04817f AC |
13251 | @item |
13252 | Reads command files specified by the @samp{-x} option. | |
13253 | @end enumerate | |
c906108c | 13254 | |
8e04817f AC |
13255 | The init file in your home directory can set options (such as @samp{set |
13256 | complaints}) that affect subsequent processing of command line options | |
13257 | and operands. Init files are not executed if you use the @samp{-nx} | |
13258 | option (@pxref{Mode Options, ,Choosing modes}). | |
c906108c | 13259 | |
8e04817f AC |
13260 | @cindex init file name |
13261 | On some configurations of @value{GDBN}, the init file is known by a | |
13262 | different name (these are typically environments where a specialized | |
13263 | form of @value{GDBN} may need to coexist with other forms, hence a | |
13264 | different name for the specialized version's init file). These are the | |
13265 | environments with special init file names: | |
c906108c | 13266 | |
8e04817f AC |
13267 | @cindex @file{.vxgdbinit} |
13268 | @itemize @bullet | |
13269 | @item | |
13270 | VxWorks (Wind River Systems real-time OS): @file{.vxgdbinit} | |
c906108c | 13271 | |
8e04817f AC |
13272 | @cindex @file{.os68gdbinit} |
13273 | @item | |
13274 | OS68K (Enea Data Systems real-time OS): @file{.os68gdbinit} | |
c906108c | 13275 | |
8e04817f AC |
13276 | @cindex @file{.esgdbinit} |
13277 | @item | |
13278 | ES-1800 (Ericsson Telecom AB M68000 emulator): @file{.esgdbinit} | |
13279 | @end itemize | |
c906108c | 13280 | |
8e04817f AC |
13281 | You can also request the execution of a command file with the |
13282 | @code{source} command: | |
c906108c | 13283 | |
8e04817f AC |
13284 | @table @code |
13285 | @kindex source | |
13286 | @item source @var{filename} | |
13287 | Execute the command file @var{filename}. | |
c906108c SS |
13288 | @end table |
13289 | ||
8e04817f | 13290 | The lines in a command file are executed sequentially. They are not |
a71ec265 DH |
13291 | printed as they are executed. An error in any command terminates |
13292 | execution of the command file and control is returned to the console. | |
c906108c | 13293 | |
8e04817f AC |
13294 | Commands that would ask for confirmation if used interactively proceed |
13295 | without asking when used in a command file. Many @value{GDBN} commands that | |
13296 | normally print messages to say what they are doing omit the messages | |
13297 | when called from command files. | |
c906108c | 13298 | |
8e04817f AC |
13299 | @value{GDBN} also accepts command input from standard input. In this |
13300 | mode, normal output goes to standard output and error output goes to | |
13301 | standard error. Errors in a command file supplied on standard input do | |
13302 | not terminate execution of the command file --- execution continues with | |
13303 | the next command. | |
c906108c | 13304 | |
474c8240 | 13305 | @smallexample |
8e04817f | 13306 | gdb < cmds > log 2>&1 |
474c8240 | 13307 | @end smallexample |
c906108c | 13308 | |
8e04817f AC |
13309 | (The syntax above will vary depending on the shell used.) This example |
13310 | will execute commands from the file @file{cmds}. All output and errors | |
13311 | would be directed to @file{log}. | |
c906108c | 13312 | |
8e04817f AC |
13313 | @node Output |
13314 | @section Commands for controlled output | |
c906108c | 13315 | |
8e04817f AC |
13316 | During the execution of a command file or a user-defined command, normal |
13317 | @value{GDBN} output is suppressed; the only output that appears is what is | |
13318 | explicitly printed by the commands in the definition. This section | |
13319 | describes three commands useful for generating exactly the output you | |
13320 | want. | |
c906108c SS |
13321 | |
13322 | @table @code | |
8e04817f AC |
13323 | @kindex echo |
13324 | @item echo @var{text} | |
13325 | @c I do not consider backslash-space a standard C escape sequence | |
13326 | @c because it is not in ANSI. | |
13327 | Print @var{text}. Nonprinting characters can be included in | |
13328 | @var{text} using C escape sequences, such as @samp{\n} to print a | |
13329 | newline. @strong{No newline is printed unless you specify one.} | |
13330 | In addition to the standard C escape sequences, a backslash followed | |
13331 | by a space stands for a space. This is useful for displaying a | |
13332 | string with spaces at the beginning or the end, since leading and | |
13333 | trailing spaces are otherwise trimmed from all arguments. | |
13334 | To print @samp{@w{ }and foo =@w{ }}, use the command | |
13335 | @samp{echo \@w{ }and foo = \@w{ }}. | |
c906108c | 13336 | |
8e04817f AC |
13337 | A backslash at the end of @var{text} can be used, as in C, to continue |
13338 | the command onto subsequent lines. For example, | |
c906108c | 13339 | |
474c8240 | 13340 | @smallexample |
8e04817f AC |
13341 | echo This is some text\n\ |
13342 | which is continued\n\ | |
13343 | onto several lines.\n | |
474c8240 | 13344 | @end smallexample |
c906108c | 13345 | |
8e04817f | 13346 | produces the same output as |
c906108c | 13347 | |
474c8240 | 13348 | @smallexample |
8e04817f AC |
13349 | echo This is some text\n |
13350 | echo which is continued\n | |
13351 | echo onto several lines.\n | |
474c8240 | 13352 | @end smallexample |
c906108c | 13353 | |
8e04817f AC |
13354 | @kindex output |
13355 | @item output @var{expression} | |
13356 | Print the value of @var{expression} and nothing but that value: no | |
13357 | newlines, no @samp{$@var{nn} = }. The value is not entered in the | |
13358 | value history either. @xref{Expressions, ,Expressions}, for more information | |
13359 | on expressions. | |
c906108c | 13360 | |
8e04817f AC |
13361 | @item output/@var{fmt} @var{expression} |
13362 | Print the value of @var{expression} in format @var{fmt}. You can use | |
13363 | the same formats as for @code{print}. @xref{Output Formats,,Output | |
13364 | formats}, for more information. | |
c906108c | 13365 | |
8e04817f AC |
13366 | @kindex printf |
13367 | @item printf @var{string}, @var{expressions}@dots{} | |
13368 | Print the values of the @var{expressions} under the control of | |
13369 | @var{string}. The @var{expressions} are separated by commas and may be | |
13370 | either numbers or pointers. Their values are printed as specified by | |
13371 | @var{string}, exactly as if your program were to execute the C | |
13372 | subroutine | |
13373 | @c FIXME: the above implies that at least all ANSI C formats are | |
13374 | @c supported, but it isn't true: %E and %G don't work (or so it seems). | |
13375 | @c Either this is a bug, or the manual should document what formats are | |
13376 | @c supported. | |
c906108c | 13377 | |
474c8240 | 13378 | @smallexample |
8e04817f | 13379 | printf (@var{string}, @var{expressions}@dots{}); |
474c8240 | 13380 | @end smallexample |
c906108c | 13381 | |
8e04817f | 13382 | For example, you can print two values in hex like this: |
c906108c | 13383 | |
8e04817f AC |
13384 | @smallexample |
13385 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo | |
13386 | @end smallexample | |
c906108c | 13387 | |
8e04817f AC |
13388 | The only backslash-escape sequences that you can use in the format |
13389 | string are the simple ones that consist of backslash followed by a | |
13390 | letter. | |
c906108c SS |
13391 | @end table |
13392 | ||
21c294e6 AC |
13393 | @node Interpreters |
13394 | @chapter Command Interpreters | |
13395 | @cindex command interpreters | |
13396 | ||
13397 | @value{GDBN} supports multiple command interpreters, and some command | |
13398 | infrastructure to allow users or user interface writers to switch | |
13399 | between interpreters or run commands in other interpreters. | |
13400 | ||
13401 | @value{GDBN} currently supports two command interpreters, the console | |
13402 | interpreter (sometimes called the command-line interpreter or @sc{cli}) | |
13403 | and the machine interface interpreter (or @sc{gdb/mi}). This manual | |
13404 | describes both of these interfaces in great detail. | |
13405 | ||
13406 | By default, @value{GDBN} will start with the console interpreter. | |
13407 | However, the user may choose to start @value{GDBN} with another | |
13408 | interpreter by specifying the @option{-i} or @option{--interpreter} | |
13409 | startup options. Defined interpreters include: | |
13410 | ||
13411 | @table @code | |
13412 | @item console | |
13413 | @cindex console interpreter | |
13414 | The traditional console or command-line interpreter. This is the most often | |
13415 | used interpreter with @value{GDBN}. With no interpreter specified at runtime, | |
13416 | @value{GDBN} will use this interpreter. | |
13417 | ||
13418 | @item mi | |
13419 | @cindex mi interpreter | |
13420 | The newest @sc{gdb/mi} interface (currently @code{mi2}). Used primarily | |
13421 | by programs wishing to use @value{GDBN} as a backend for a debugger GUI | |
13422 | or an IDE. For more information, see @ref{GDB/MI, ,The @sc{gdb/mi} | |
13423 | Interface}. | |
13424 | ||
13425 | @item mi2 | |
13426 | @cindex mi2 interpreter | |
13427 | The current @sc{gdb/mi} interface. | |
13428 | ||
13429 | @item mi1 | |
13430 | @cindex mi1 interpreter | |
13431 | The @sc{gdb/mi} interface included in @value{GDBN} 5.1, 5.2, and 5.3. | |
13432 | ||
13433 | @end table | |
13434 | ||
13435 | @cindex invoke another interpreter | |
13436 | The interpreter being used by @value{GDBN} may not be dynamically | |
13437 | switched at runtime. Although possible, this could lead to a very | |
13438 | precarious situation. Consider an IDE using @sc{gdb/mi}. If a user | |
13439 | enters the command "interpreter-set console" in a console view, | |
13440 | @value{GDBN} would switch to using the console interpreter, rendering | |
13441 | the IDE inoperable! | |
13442 | ||
13443 | @kindex interpreter-exec | |
13444 | Although you may only choose a single interpreter at startup, you may execute | |
13445 | commands in any interpreter from the current interpreter using the appropriate | |
13446 | command. If you are running the console interpreter, simply use the | |
13447 | @code{interpreter-exec} command: | |
13448 | ||
13449 | @smallexample | |
13450 | interpreter-exec mi "-data-list-register-names" | |
13451 | @end smallexample | |
13452 | ||
13453 | @sc{gdb/mi} has a similar command, although it is only available in versions of | |
13454 | @value{GDBN} which support @sc{gdb/mi} version 2 (or greater). | |
13455 | ||
8e04817f AC |
13456 | @node TUI |
13457 | @chapter @value{GDBN} Text User Interface | |
13458 | @cindex TUI | |
c906108c | 13459 | |
8e04817f AC |
13460 | @menu |
13461 | * TUI Overview:: TUI overview | |
13462 | * TUI Keys:: TUI key bindings | |
7cf36c78 | 13463 | * TUI Single Key Mode:: TUI single key mode |
8e04817f AC |
13464 | * TUI Commands:: TUI specific commands |
13465 | * TUI Configuration:: TUI configuration variables | |
13466 | @end menu | |
c906108c | 13467 | |
8e04817f AC |
13468 | The @value{GDBN} Text User Interface, TUI in short, |
13469 | is a terminal interface which uses the @code{curses} library | |
13470 | to show the source file, the assembly output, the program registers | |
13471 | and @value{GDBN} commands in separate text windows. | |
13472 | The TUI is available only when @value{GDBN} is configured | |
13473 | with the @code{--enable-tui} configure option (@pxref{Configure Options}). | |
c906108c | 13474 | |
8e04817f AC |
13475 | @node TUI Overview |
13476 | @section TUI overview | |
c906108c | 13477 | |
8e04817f AC |
13478 | The TUI has two display modes that can be switched while |
13479 | @value{GDBN} runs: | |
c906108c | 13480 | |
8e04817f AC |
13481 | @itemize @bullet |
13482 | @item | |
13483 | A curses (or TUI) mode in which it displays several text | |
13484 | windows on the terminal. | |
c906108c | 13485 | |
8e04817f AC |
13486 | @item |
13487 | A standard mode which corresponds to the @value{GDBN} configured without | |
13488 | the TUI. | |
13489 | @end itemize | |
c906108c | 13490 | |
8e04817f AC |
13491 | In the TUI mode, @value{GDBN} can display several text window |
13492 | on the terminal: | |
c906108c | 13493 | |
8e04817f AC |
13494 | @table @emph |
13495 | @item command | |
13496 | This window is the @value{GDBN} command window with the @value{GDBN} | |
13497 | prompt and the @value{GDBN} outputs. The @value{GDBN} input is still | |
13498 | managed using readline but through the TUI. The @emph{command} | |
13499 | window is always visible. | |
c906108c | 13500 | |
8e04817f AC |
13501 | @item source |
13502 | The source window shows the source file of the program. The current | |
13503 | line as well as active breakpoints are displayed in this window. | |
c906108c | 13504 | |
8e04817f AC |
13505 | @item assembly |
13506 | The assembly window shows the disassembly output of the program. | |
c906108c | 13507 | |
8e04817f AC |
13508 | @item register |
13509 | This window shows the processor registers. It detects when | |
13510 | a register is changed and when this is the case, registers that have | |
13511 | changed are highlighted. | |
c906108c | 13512 | |
c906108c SS |
13513 | @end table |
13514 | ||
269c21fe SC |
13515 | The source and assembly windows show the current program position |
13516 | by highlighting the current line and marking them with the @samp{>} marker. | |
13517 | Breakpoints are also indicated with two markers. A first one | |
13518 | indicates the breakpoint type: | |
13519 | ||
13520 | @table @code | |
13521 | @item B | |
13522 | Breakpoint which was hit at least once. | |
13523 | ||
13524 | @item b | |
13525 | Breakpoint which was never hit. | |
13526 | ||
13527 | @item H | |
13528 | Hardware breakpoint which was hit at least once. | |
13529 | ||
13530 | @item h | |
13531 | Hardware breakpoint which was never hit. | |
13532 | ||
13533 | @end table | |
13534 | ||
13535 | The second marker indicates whether the breakpoint is enabled or not: | |
13536 | ||
13537 | @table @code | |
13538 | @item + | |
13539 | Breakpoint is enabled. | |
13540 | ||
13541 | @item - | |
13542 | Breakpoint is disabled. | |
13543 | ||
13544 | @end table | |
13545 | ||
8e04817f AC |
13546 | The source, assembly and register windows are attached to the thread |
13547 | and the frame position. They are updated when the current thread | |
13548 | changes, when the frame changes or when the program counter changes. | |
13549 | These three windows are arranged by the TUI according to several | |
13550 | layouts. The layout defines which of these three windows are visible. | |
13551 | The following layouts are available: | |
c906108c | 13552 | |
8e04817f AC |
13553 | @itemize @bullet |
13554 | @item | |
13555 | source | |
2df3850c | 13556 | |
8e04817f AC |
13557 | @item |
13558 | assembly | |
13559 | ||
13560 | @item | |
13561 | source and assembly | |
13562 | ||
13563 | @item | |
13564 | source and registers | |
c906108c | 13565 | |
8e04817f AC |
13566 | @item |
13567 | assembly and registers | |
2df3850c | 13568 | |
8e04817f | 13569 | @end itemize |
c906108c | 13570 | |
b7bb15bc SC |
13571 | On top of the command window a status line gives various information |
13572 | concerning the current process begin debugged. The status line is | |
13573 | updated when the information it shows changes. The following fields | |
13574 | are displayed: | |
13575 | ||
13576 | @table @emph | |
13577 | @item target | |
13578 | Indicates the current gdb target | |
13579 | (@pxref{Targets, ,Specifying a Debugging Target}). | |
13580 | ||
13581 | @item process | |
13582 | Gives information about the current process or thread number. | |
13583 | When no process is being debugged, this field is set to @code{No process}. | |
13584 | ||
13585 | @item function | |
13586 | Gives the current function name for the selected frame. | |
13587 | The name is demangled if demangling is turned on (@pxref{Print Settings}). | |
13588 | When there is no symbol corresponding to the current program counter | |
13589 | the string @code{??} is displayed. | |
13590 | ||
13591 | @item line | |
13592 | Indicates the current line number for the selected frame. | |
13593 | When the current line number is not known the string @code{??} is displayed. | |
13594 | ||
13595 | @item pc | |
13596 | Indicates the current program counter address. | |
13597 | ||
13598 | @end table | |
13599 | ||
8e04817f AC |
13600 | @node TUI Keys |
13601 | @section TUI Key Bindings | |
13602 | @cindex TUI key bindings | |
c906108c | 13603 | |
8e04817f AC |
13604 | The TUI installs several key bindings in the readline keymaps |
13605 | (@pxref{Command Line Editing}). | |
13606 | They allow to leave or enter in the TUI mode or they operate | |
7cf36c78 SC |
13607 | directly on the TUI layout and windows. The TUI also provides |
13608 | a @emph{SingleKey} keymap which binds several keys directly to | |
13609 | @value{GDBN} commands. The following key bindings | |
8e04817f | 13610 | are installed for both TUI mode and the @value{GDBN} standard mode. |
c906108c | 13611 | |
8e04817f AC |
13612 | @table @kbd |
13613 | @kindex C-x C-a | |
13614 | @item C-x C-a | |
13615 | @kindex C-x a | |
13616 | @itemx C-x a | |
13617 | @kindex C-x A | |
13618 | @itemx C-x A | |
13619 | Enter or leave the TUI mode. When the TUI mode is left, | |
13620 | the curses window management is left and @value{GDBN} operates using | |
13621 | its standard mode writing on the terminal directly. When the TUI | |
13622 | mode is entered, the control is given back to the curses windows. | |
13623 | The screen is then refreshed. | |
c906108c | 13624 | |
8e04817f AC |
13625 | @kindex C-x 1 |
13626 | @item C-x 1 | |
13627 | Use a TUI layout with only one window. The layout will | |
13628 | either be @samp{source} or @samp{assembly}. When the TUI mode | |
13629 | is not active, it will switch to the TUI mode. | |
2df3850c | 13630 | |
8e04817f | 13631 | Think of this key binding as the Emacs @kbd{C-x 1} binding. |
c906108c | 13632 | |
8e04817f AC |
13633 | @kindex C-x 2 |
13634 | @item C-x 2 | |
13635 | Use a TUI layout with at least two windows. When the current | |
13636 | layout shows already two windows, a next layout with two windows is used. | |
13637 | When a new layout is chosen, one window will always be common to the | |
13638 | previous layout and the new one. | |
c906108c | 13639 | |
8e04817f | 13640 | Think of it as the Emacs @kbd{C-x 2} binding. |
2df3850c | 13641 | |
7cf36c78 SC |
13642 | @kindex C-x s |
13643 | @item C-x s | |
13644 | Use the TUI @emph{SingleKey} keymap that binds single key to gdb commands | |
13645 | (@pxref{TUI Single Key Mode}). | |
13646 | ||
c906108c SS |
13647 | @end table |
13648 | ||
8e04817f | 13649 | The following key bindings are handled only by the TUI mode: |
5d161b24 | 13650 | |
8e04817f AC |
13651 | @table @key |
13652 | @kindex PgUp | |
13653 | @item PgUp | |
13654 | Scroll the active window one page up. | |
c906108c | 13655 | |
8e04817f AC |
13656 | @kindex PgDn |
13657 | @item PgDn | |
13658 | Scroll the active window one page down. | |
c906108c | 13659 | |
8e04817f AC |
13660 | @kindex Up |
13661 | @item Up | |
13662 | Scroll the active window one line up. | |
c906108c | 13663 | |
8e04817f AC |
13664 | @kindex Down |
13665 | @item Down | |
13666 | Scroll the active window one line down. | |
c906108c | 13667 | |
8e04817f AC |
13668 | @kindex Left |
13669 | @item Left | |
13670 | Scroll the active window one column left. | |
c906108c | 13671 | |
8e04817f AC |
13672 | @kindex Right |
13673 | @item Right | |
13674 | Scroll the active window one column right. | |
c906108c | 13675 | |
8e04817f AC |
13676 | @kindex C-L |
13677 | @item C-L | |
13678 | Refresh the screen. | |
c906108c | 13679 | |
8e04817f | 13680 | @end table |
c906108c | 13681 | |
8e04817f AC |
13682 | In the TUI mode, the arrow keys are used by the active window |
13683 | for scrolling. This means they are not available for readline. It is | |
13684 | necessary to use other readline key bindings such as @key{C-p}, @key{C-n}, | |
13685 | @key{C-b} and @key{C-f}. | |
13686 | ||
7cf36c78 SC |
13687 | @node TUI Single Key Mode |
13688 | @section TUI Single Key Mode | |
13689 | @cindex TUI single key mode | |
13690 | ||
13691 | The TUI provides a @emph{SingleKey} mode in which it installs a particular | |
13692 | key binding in the readline keymaps to connect single keys to | |
13693 | some gdb commands. | |
13694 | ||
13695 | @table @kbd | |
13696 | @kindex c @r{(SingleKey TUI key)} | |
13697 | @item c | |
13698 | continue | |
13699 | ||
13700 | @kindex d @r{(SingleKey TUI key)} | |
13701 | @item d | |
13702 | down | |
13703 | ||
13704 | @kindex f @r{(SingleKey TUI key)} | |
13705 | @item f | |
13706 | finish | |
13707 | ||
13708 | @kindex n @r{(SingleKey TUI key)} | |
13709 | @item n | |
13710 | next | |
13711 | ||
13712 | @kindex q @r{(SingleKey TUI key)} | |
13713 | @item q | |
13714 | exit the @emph{SingleKey} mode. | |
13715 | ||
13716 | @kindex r @r{(SingleKey TUI key)} | |
13717 | @item r | |
13718 | run | |
13719 | ||
13720 | @kindex s @r{(SingleKey TUI key)} | |
13721 | @item s | |
13722 | step | |
13723 | ||
13724 | @kindex u @r{(SingleKey TUI key)} | |
13725 | @item u | |
13726 | up | |
13727 | ||
13728 | @kindex v @r{(SingleKey TUI key)} | |
13729 | @item v | |
13730 | info locals | |
13731 | ||
13732 | @kindex w @r{(SingleKey TUI key)} | |
13733 | @item w | |
13734 | where | |
13735 | ||
13736 | @end table | |
13737 | ||
13738 | Other keys temporarily switch to the @value{GDBN} command prompt. | |
13739 | The key that was pressed is inserted in the editing buffer so that | |
13740 | it is possible to type most @value{GDBN} commands without interaction | |
13741 | with the TUI @emph{SingleKey} mode. Once the command is entered the TUI | |
13742 | @emph{SingleKey} mode is restored. The only way to permanently leave | |
13743 | this mode is by hitting @key{q} or @samp{@key{C-x} @key{s}}. | |
13744 | ||
13745 | ||
8e04817f AC |
13746 | @node TUI Commands |
13747 | @section TUI specific commands | |
13748 | @cindex TUI commands | |
13749 | ||
13750 | The TUI has specific commands to control the text windows. | |
13751 | These commands are always available, that is they do not depend on | |
13752 | the current terminal mode in which @value{GDBN} runs. When @value{GDBN} | |
13753 | is in the standard mode, using these commands will automatically switch | |
13754 | in the TUI mode. | |
c906108c SS |
13755 | |
13756 | @table @code | |
3d757584 SC |
13757 | @item info win |
13758 | @kindex info win | |
13759 | List and give the size of all displayed windows. | |
13760 | ||
8e04817f AC |
13761 | @item layout next |
13762 | @kindex layout next | |
13763 | Display the next layout. | |
2df3850c | 13764 | |
8e04817f AC |
13765 | @item layout prev |
13766 | @kindex layout prev | |
13767 | Display the previous layout. | |
c906108c | 13768 | |
8e04817f AC |
13769 | @item layout src |
13770 | @kindex layout src | |
13771 | Display the source window only. | |
c906108c | 13772 | |
8e04817f AC |
13773 | @item layout asm |
13774 | @kindex layout asm | |
13775 | Display the assembly window only. | |
c906108c | 13776 | |
8e04817f AC |
13777 | @item layout split |
13778 | @kindex layout split | |
13779 | Display the source and assembly window. | |
c906108c | 13780 | |
8e04817f AC |
13781 | @item layout regs |
13782 | @kindex layout regs | |
13783 | Display the register window together with the source or assembly window. | |
13784 | ||
13785 | @item focus next | prev | src | asm | regs | split | |
13786 | @kindex focus | |
13787 | Set the focus to the named window. | |
13788 | This command allows to change the active window so that scrolling keys | |
13789 | can be affected to another window. | |
c906108c | 13790 | |
8e04817f AC |
13791 | @item refresh |
13792 | @kindex refresh | |
13793 | Refresh the screen. This is similar to using @key{C-L} key. | |
c906108c | 13794 | |
8e04817f AC |
13795 | @item update |
13796 | @kindex update | |
13797 | Update the source window and the current execution point. | |
c906108c | 13798 | |
8e04817f AC |
13799 | @item winheight @var{name} +@var{count} |
13800 | @itemx winheight @var{name} -@var{count} | |
13801 | @kindex winheight | |
13802 | Change the height of the window @var{name} by @var{count} | |
13803 | lines. Positive counts increase the height, while negative counts | |
13804 | decrease it. | |
2df3850c | 13805 | |
c906108c SS |
13806 | @end table |
13807 | ||
8e04817f AC |
13808 | @node TUI Configuration |
13809 | @section TUI configuration variables | |
13810 | @cindex TUI configuration variables | |
c906108c | 13811 | |
8e04817f AC |
13812 | The TUI has several configuration variables that control the |
13813 | appearance of windows on the terminal. | |
c906108c | 13814 | |
8e04817f AC |
13815 | @table @code |
13816 | @item set tui border-kind @var{kind} | |
13817 | @kindex set tui border-kind | |
13818 | Select the border appearance for the source, assembly and register windows. | |
13819 | The possible values are the following: | |
13820 | @table @code | |
13821 | @item space | |
13822 | Use a space character to draw the border. | |
c906108c | 13823 | |
8e04817f AC |
13824 | @item ascii |
13825 | Use ascii characters + - and | to draw the border. | |
c906108c | 13826 | |
8e04817f AC |
13827 | @item acs |
13828 | Use the Alternate Character Set to draw the border. The border is | |
13829 | drawn using character line graphics if the terminal supports them. | |
c78b4128 | 13830 | |
8e04817f | 13831 | @end table |
c78b4128 | 13832 | |
8e04817f AC |
13833 | @item set tui active-border-mode @var{mode} |
13834 | @kindex set tui active-border-mode | |
13835 | Select the attributes to display the border of the active window. | |
13836 | The possible values are @code{normal}, @code{standout}, @code{reverse}, | |
13837 | @code{half}, @code{half-standout}, @code{bold} and @code{bold-standout}. | |
c78b4128 | 13838 | |
8e04817f AC |
13839 | @item set tui border-mode @var{mode} |
13840 | @kindex set tui border-mode | |
13841 | Select the attributes to display the border of other windows. | |
13842 | The @var{mode} can be one of the following: | |
13843 | @table @code | |
13844 | @item normal | |
13845 | Use normal attributes to display the border. | |
c906108c | 13846 | |
8e04817f AC |
13847 | @item standout |
13848 | Use standout mode. | |
c906108c | 13849 | |
8e04817f AC |
13850 | @item reverse |
13851 | Use reverse video mode. | |
c906108c | 13852 | |
8e04817f AC |
13853 | @item half |
13854 | Use half bright mode. | |
c906108c | 13855 | |
8e04817f AC |
13856 | @item half-standout |
13857 | Use half bright and standout mode. | |
c906108c | 13858 | |
8e04817f AC |
13859 | @item bold |
13860 | Use extra bright or bold mode. | |
c78b4128 | 13861 | |
8e04817f AC |
13862 | @item bold-standout |
13863 | Use extra bright or bold and standout mode. | |
c78b4128 | 13864 | |
8e04817f | 13865 | @end table |
c78b4128 | 13866 | |
8e04817f | 13867 | @end table |
c78b4128 | 13868 | |
8e04817f AC |
13869 | @node Emacs |
13870 | @chapter Using @value{GDBN} under @sc{gnu} Emacs | |
c78b4128 | 13871 | |
8e04817f AC |
13872 | @cindex Emacs |
13873 | @cindex @sc{gnu} Emacs | |
13874 | A special interface allows you to use @sc{gnu} Emacs to view (and | |
13875 | edit) the source files for the program you are debugging with | |
13876 | @value{GDBN}. | |
c906108c | 13877 | |
8e04817f AC |
13878 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the |
13879 | executable file you want to debug as an argument. This command starts | |
13880 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly | |
13881 | created Emacs buffer. | |
13882 | @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.) | |
c906108c | 13883 | |
8e04817f AC |
13884 | Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two |
13885 | things: | |
c906108c | 13886 | |
8e04817f AC |
13887 | @itemize @bullet |
13888 | @item | |
13889 | All ``terminal'' input and output goes through the Emacs buffer. | |
13890 | @end itemize | |
c906108c | 13891 | |
8e04817f AC |
13892 | This applies both to @value{GDBN} commands and their output, and to the input |
13893 | and output done by the program you are debugging. | |
bf0184be | 13894 | |
8e04817f AC |
13895 | This is useful because it means that you can copy the text of previous |
13896 | commands and input them again; you can even use parts of the output | |
13897 | in this way. | |
bf0184be | 13898 | |
8e04817f AC |
13899 | All the facilities of Emacs' Shell mode are available for interacting |
13900 | with your program. In particular, you can send signals the usual | |
13901 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a | |
13902 | stop. | |
bf0184be | 13903 | |
8e04817f | 13904 | @itemize @bullet |
bf0184be | 13905 | @item |
8e04817f AC |
13906 | @value{GDBN} displays source code through Emacs. |
13907 | @end itemize | |
bf0184be | 13908 | |
8e04817f AC |
13909 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the |
13910 | source file for that frame and puts an arrow (@samp{=>}) at the | |
13911 | left margin of the current line. Emacs uses a separate buffer for | |
13912 | source display, and splits the screen to show both your @value{GDBN} session | |
13913 | and the source. | |
bf0184be | 13914 | |
8e04817f AC |
13915 | Explicit @value{GDBN} @code{list} or search commands still produce output as |
13916 | usual, but you probably have no reason to use them from Emacs. | |
c906108c | 13917 | |
8e04817f AC |
13918 | @quotation |
13919 | @emph{Warning:} If the directory where your program resides is not your | |
13920 | current directory, it can be easy to confuse Emacs about the location of | |
13921 | the source files, in which case the auxiliary display buffer does not | |
13922 | appear to show your source. @value{GDBN} can find programs by searching your | |
13923 | environment's @code{PATH} variable, so the @value{GDBN} input and output | |
13924 | session proceeds normally; but Emacs does not get enough information | |
13925 | back from @value{GDBN} to locate the source files in this situation. To | |
13926 | avoid this problem, either start @value{GDBN} mode from the directory where | |
13927 | your program resides, or specify an absolute file name when prompted for the | |
13928 | @kbd{M-x gdb} argument. | |
c906108c | 13929 | |
8e04817f AC |
13930 | A similar confusion can result if you use the @value{GDBN} @code{file} command to |
13931 | switch to debugging a program in some other location, from an existing | |
13932 | @value{GDBN} buffer in Emacs. | |
13933 | @end quotation | |
13934 | ||
13935 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If | |
13936 | you need to call @value{GDBN} by a different name (for example, if you keep | |
13937 | several configurations around, with different names) you can set the | |
13938 | Emacs variable @code{gdb-command-name}; for example, | |
13939 | ||
474c8240 | 13940 | @smallexample |
8e04817f | 13941 | (setq gdb-command-name "mygdb") |
474c8240 | 13942 | @end smallexample |
8e04817f AC |
13943 | |
13944 | @noindent | |
13945 | (preceded by @kbd{M-:} or @kbd{ESC :}, or typed in the @code{*scratch*} buffer, or | |
13946 | in your @file{.emacs} file) makes Emacs call the program named | |
13947 | ``@code{mygdb}'' instead. | |
13948 | ||
13949 | In the @value{GDBN} I/O buffer, you can use these special Emacs commands in | |
13950 | addition to the standard Shell mode commands: | |
c906108c | 13951 | |
8e04817f AC |
13952 | @table @kbd |
13953 | @item C-h m | |
13954 | Describe the features of Emacs' @value{GDBN} Mode. | |
c906108c | 13955 | |
8e04817f AC |
13956 | @item M-s |
13957 | Execute to another source line, like the @value{GDBN} @code{step} command; also | |
13958 | update the display window to show the current file and location. | |
c906108c | 13959 | |
8e04817f AC |
13960 | @item M-n |
13961 | Execute to next source line in this function, skipping all function | |
13962 | calls, like the @value{GDBN} @code{next} command. Then update the display window | |
13963 | to show the current file and location. | |
c906108c | 13964 | |
8e04817f AC |
13965 | @item M-i |
13966 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update | |
13967 | display window accordingly. | |
c906108c | 13968 | |
8e04817f AC |
13969 | @item M-x gdb-nexti |
13970 | Execute to next instruction, using the @value{GDBN} @code{nexti} command; update | |
13971 | display window accordingly. | |
c906108c | 13972 | |
8e04817f AC |
13973 | @item C-c C-f |
13974 | Execute until exit from the selected stack frame, like the @value{GDBN} | |
13975 | @code{finish} command. | |
c906108c | 13976 | |
8e04817f AC |
13977 | @item M-c |
13978 | Continue execution of your program, like the @value{GDBN} @code{continue} | |
13979 | command. | |
b433d00b | 13980 | |
8e04817f | 13981 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. |
b433d00b | 13982 | |
8e04817f AC |
13983 | @item M-u |
13984 | Go up the number of frames indicated by the numeric argument | |
13985 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), | |
13986 | like the @value{GDBN} @code{up} command. | |
b433d00b | 13987 | |
8e04817f | 13988 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. |
c906108c | 13989 | |
8e04817f AC |
13990 | @item M-d |
13991 | Go down the number of frames indicated by the numeric argument, like the | |
13992 | @value{GDBN} @code{down} command. | |
c906108c | 13993 | |
8e04817f | 13994 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. |
c906108c | 13995 | |
8e04817f AC |
13996 | @item C-x & |
13997 | Read the number where the cursor is positioned, and insert it at the end | |
13998 | of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code | |
13999 | around an address that was displayed earlier, type @kbd{disassemble}; | |
14000 | then move the cursor to the address display, and pick up the | |
14001 | argument for @code{disassemble} by typing @kbd{C-x &}. | |
c906108c | 14002 | |
8e04817f AC |
14003 | You can customize this further by defining elements of the list |
14004 | @code{gdb-print-command}; once it is defined, you can format or | |
14005 | otherwise process numbers picked up by @kbd{C-x &} before they are | |
14006 | inserted. A numeric argument to @kbd{C-x &} indicates that you | |
14007 | wish special formatting, and also acts as an index to pick an element of the | |
14008 | list. If the list element is a string, the number to be inserted is | |
14009 | formatted using the Emacs function @code{format}; otherwise the number | |
14010 | is passed as an argument to the corresponding list element. | |
14011 | @end table | |
c906108c | 14012 | |
8e04817f AC |
14013 | In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) |
14014 | tells @value{GDBN} to set a breakpoint on the source line point is on. | |
c906108c | 14015 | |
8e04817f AC |
14016 | If you accidentally delete the source-display buffer, an easy way to get |
14017 | it back is to type the command @code{f} in the @value{GDBN} buffer, to | |
14018 | request a frame display; when you run under Emacs, this recreates | |
14019 | the source buffer if necessary to show you the context of the current | |
14020 | frame. | |
c906108c | 14021 | |
8e04817f AC |
14022 | The source files displayed in Emacs are in ordinary Emacs buffers |
14023 | which are visiting the source files in the usual way. You can edit | |
14024 | the files with these buffers if you wish; but keep in mind that @value{GDBN} | |
14025 | communicates with Emacs in terms of line numbers. If you add or | |
14026 | delete lines from the text, the line numbers that @value{GDBN} knows cease | |
14027 | to correspond properly with the code. | |
c906108c | 14028 | |
8e04817f AC |
14029 | @c The following dropped because Epoch is nonstandard. Reactivate |
14030 | @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990 | |
14031 | @ignore | |
14032 | @kindex Emacs Epoch environment | |
14033 | @kindex Epoch | |
14034 | @kindex inspect | |
c906108c | 14035 | |
8e04817f AC |
14036 | Version 18 of @sc{gnu} Emacs has a built-in window system |
14037 | called the @code{epoch} | |
14038 | environment. Users of this environment can use a new command, | |
14039 | @code{inspect} which performs identically to @code{print} except that | |
14040 | each value is printed in its own window. | |
14041 | @end ignore | |
c906108c | 14042 | |
8e04817f AC |
14043 | @include annotate.texi |
14044 | @include gdbmi.texinfo | |
c906108c | 14045 | |
8e04817f AC |
14046 | @node GDB Bugs |
14047 | @chapter Reporting Bugs in @value{GDBN} | |
14048 | @cindex bugs in @value{GDBN} | |
14049 | @cindex reporting bugs in @value{GDBN} | |
c906108c | 14050 | |
8e04817f | 14051 | Your bug reports play an essential role in making @value{GDBN} reliable. |
c906108c | 14052 | |
8e04817f AC |
14053 | Reporting a bug may help you by bringing a solution to your problem, or it |
14054 | may not. But in any case the principal function of a bug report is to help | |
14055 | the entire community by making the next version of @value{GDBN} work better. Bug | |
14056 | reports are your contribution to the maintenance of @value{GDBN}. | |
c906108c | 14057 | |
8e04817f AC |
14058 | In order for a bug report to serve its purpose, you must include the |
14059 | information that enables us to fix the bug. | |
c4555f82 SC |
14060 | |
14061 | @menu | |
8e04817f AC |
14062 | * Bug Criteria:: Have you found a bug? |
14063 | * Bug Reporting:: How to report bugs | |
c4555f82 SC |
14064 | @end menu |
14065 | ||
8e04817f AC |
14066 | @node Bug Criteria |
14067 | @section Have you found a bug? | |
14068 | @cindex bug criteria | |
c4555f82 | 14069 | |
8e04817f | 14070 | If you are not sure whether you have found a bug, here are some guidelines: |
c4555f82 SC |
14071 | |
14072 | @itemize @bullet | |
8e04817f AC |
14073 | @cindex fatal signal |
14074 | @cindex debugger crash | |
14075 | @cindex crash of debugger | |
c4555f82 | 14076 | @item |
8e04817f AC |
14077 | If the debugger gets a fatal signal, for any input whatever, that is a |
14078 | @value{GDBN} bug. Reliable debuggers never crash. | |
14079 | ||
14080 | @cindex error on valid input | |
14081 | @item | |
14082 | If @value{GDBN} produces an error message for valid input, that is a | |
14083 | bug. (Note that if you're cross debugging, the problem may also be | |
14084 | somewhere in the connection to the target.) | |
c4555f82 | 14085 | |
8e04817f | 14086 | @cindex invalid input |
c4555f82 | 14087 | @item |
8e04817f AC |
14088 | If @value{GDBN} does not produce an error message for invalid input, |
14089 | that is a bug. However, you should note that your idea of | |
14090 | ``invalid input'' might be our idea of ``an extension'' or ``support | |
14091 | for traditional practice''. | |
14092 | ||
14093 | @item | |
14094 | If you are an experienced user of debugging tools, your suggestions | |
14095 | for improvement of @value{GDBN} are welcome in any case. | |
c4555f82 SC |
14096 | @end itemize |
14097 | ||
8e04817f AC |
14098 | @node Bug Reporting |
14099 | @section How to report bugs | |
14100 | @cindex bug reports | |
14101 | @cindex @value{GDBN} bugs, reporting | |
14102 | ||
14103 | A number of companies and individuals offer support for @sc{gnu} products. | |
14104 | If you obtained @value{GDBN} from a support organization, we recommend you | |
14105 | contact that organization first. | |
14106 | ||
14107 | You can find contact information for many support companies and | |
14108 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
14109 | distribution. | |
14110 | @c should add a web page ref... | |
14111 | ||
129188f6 AC |
14112 | In any event, we also recommend that you submit bug reports for |
14113 | @value{GDBN}. The prefered method is to submit them directly using | |
14114 | @uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web | |
14115 | page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can | |
14116 | be used. | |
8e04817f AC |
14117 | |
14118 | @strong{Do not send bug reports to @samp{info-gdb}, or to | |
14119 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do | |
14120 | not want to receive bug reports. Those that do have arranged to receive | |
14121 | @samp{bug-gdb}. | |
14122 | ||
14123 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which | |
14124 | serves as a repeater. The mailing list and the newsgroup carry exactly | |
14125 | the same messages. Often people think of posting bug reports to the | |
14126 | newsgroup instead of mailing them. This appears to work, but it has one | |
14127 | problem which can be crucial: a newsgroup posting often lacks a mail | |
14128 | path back to the sender. Thus, if we need to ask for more information, | |
14129 | we may be unable to reach you. For this reason, it is better to send | |
14130 | bug reports to the mailing list. | |
c4555f82 | 14131 | |
8e04817f AC |
14132 | The fundamental principle of reporting bugs usefully is this: |
14133 | @strong{report all the facts}. If you are not sure whether to state a | |
14134 | fact or leave it out, state it! | |
c4555f82 | 14135 | |
8e04817f AC |
14136 | Often people omit facts because they think they know what causes the |
14137 | problem and assume that some details do not matter. Thus, you might | |
14138 | assume that the name of the variable you use in an example does not matter. | |
14139 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a | |
14140 | stray memory reference which happens to fetch from the location where that | |
14141 | name is stored in memory; perhaps, if the name were different, the contents | |
14142 | of that location would fool the debugger into doing the right thing despite | |
14143 | the bug. Play it safe and give a specific, complete example. That is the | |
14144 | easiest thing for you to do, and the most helpful. | |
c4555f82 | 14145 | |
8e04817f AC |
14146 | Keep in mind that the purpose of a bug report is to enable us to fix the |
14147 | bug. It may be that the bug has been reported previously, but neither | |
14148 | you nor we can know that unless your bug report is complete and | |
14149 | self-contained. | |
c4555f82 | 14150 | |
8e04817f AC |
14151 | Sometimes people give a few sketchy facts and ask, ``Does this ring a |
14152 | bell?'' Those bug reports are useless, and we urge everyone to | |
14153 | @emph{refuse to respond to them} except to chide the sender to report | |
14154 | bugs properly. | |
14155 | ||
14156 | To enable us to fix the bug, you should include all these things: | |
c4555f82 SC |
14157 | |
14158 | @itemize @bullet | |
14159 | @item | |
8e04817f AC |
14160 | The version of @value{GDBN}. @value{GDBN} announces it if you start |
14161 | with no arguments; you can also print it at any time using @code{show | |
14162 | version}. | |
c4555f82 | 14163 | |
8e04817f AC |
14164 | Without this, we will not know whether there is any point in looking for |
14165 | the bug in the current version of @value{GDBN}. | |
c4555f82 SC |
14166 | |
14167 | @item | |
8e04817f AC |
14168 | The type of machine you are using, and the operating system name and |
14169 | version number. | |
c4555f82 SC |
14170 | |
14171 | @item | |
8e04817f AC |
14172 | What compiler (and its version) was used to compile @value{GDBN}---e.g. |
14173 | ``@value{GCC}--2.8.1''. | |
c4555f82 SC |
14174 | |
14175 | @item | |
8e04817f AC |
14176 | What compiler (and its version) was used to compile the program you are |
14177 | debugging---e.g. ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP | |
14178 | C Compiler''. For GCC, you can say @code{gcc --version} to get this | |
14179 | information; for other compilers, see the documentation for those | |
14180 | compilers. | |
c4555f82 | 14181 | |
8e04817f AC |
14182 | @item |
14183 | The command arguments you gave the compiler to compile your example and | |
14184 | observe the bug. For example, did you use @samp{-O}? To guarantee | |
14185 | you will not omit something important, list them all. A copy of the | |
14186 | Makefile (or the output from make) is sufficient. | |
c4555f82 | 14187 | |
8e04817f AC |
14188 | If we were to try to guess the arguments, we would probably guess wrong |
14189 | and then we might not encounter the bug. | |
c4555f82 | 14190 | |
8e04817f AC |
14191 | @item |
14192 | A complete input script, and all necessary source files, that will | |
14193 | reproduce the bug. | |
c4555f82 | 14194 | |
8e04817f AC |
14195 | @item |
14196 | A description of what behavior you observe that you believe is | |
14197 | incorrect. For example, ``It gets a fatal signal.'' | |
c4555f82 | 14198 | |
8e04817f AC |
14199 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we |
14200 | will certainly notice it. But if the bug is incorrect output, we might | |
14201 | not notice unless it is glaringly wrong. You might as well not give us | |
14202 | a chance to make a mistake. | |
c4555f82 | 14203 | |
8e04817f AC |
14204 | Even if the problem you experience is a fatal signal, you should still |
14205 | say so explicitly. Suppose something strange is going on, such as, your | |
14206 | copy of @value{GDBN} is out of synch, or you have encountered a bug in | |
14207 | the C library on your system. (This has happened!) Your copy might | |
14208 | crash and ours would not. If you told us to expect a crash, then when | |
14209 | ours fails to crash, we would know that the bug was not happening for | |
14210 | us. If you had not told us to expect a crash, then we would not be able | |
14211 | to draw any conclusion from our observations. | |
c4555f82 | 14212 | |
8e04817f AC |
14213 | @item |
14214 | If you wish to suggest changes to the @value{GDBN} source, send us context | |
14215 | diffs. If you even discuss something in the @value{GDBN} source, refer to | |
14216 | it by context, not by line number. | |
c4555f82 | 14217 | |
8e04817f AC |
14218 | The line numbers in our development sources will not match those in your |
14219 | sources. Your line numbers would convey no useful information to us. | |
c4555f82 | 14220 | |
8e04817f | 14221 | @end itemize |
c4555f82 | 14222 | |
8e04817f | 14223 | Here are some things that are not necessary: |
c4555f82 | 14224 | |
8e04817f AC |
14225 | @itemize @bullet |
14226 | @item | |
14227 | A description of the envelope of the bug. | |
c4555f82 | 14228 | |
8e04817f AC |
14229 | Often people who encounter a bug spend a lot of time investigating |
14230 | which changes to the input file will make the bug go away and which | |
14231 | changes will not affect it. | |
c4555f82 | 14232 | |
8e04817f AC |
14233 | This is often time consuming and not very useful, because the way we |
14234 | will find the bug is by running a single example under the debugger | |
14235 | with breakpoints, not by pure deduction from a series of examples. | |
14236 | We recommend that you save your time for something else. | |
c4555f82 | 14237 | |
8e04817f AC |
14238 | Of course, if you can find a simpler example to report @emph{instead} |
14239 | of the original one, that is a convenience for us. Errors in the | |
14240 | output will be easier to spot, running under the debugger will take | |
14241 | less time, and so on. | |
c4555f82 | 14242 | |
8e04817f AC |
14243 | However, simplification is not vital; if you do not want to do this, |
14244 | report the bug anyway and send us the entire test case you used. | |
c4555f82 | 14245 | |
8e04817f AC |
14246 | @item |
14247 | A patch for the bug. | |
c4555f82 | 14248 | |
8e04817f AC |
14249 | A patch for the bug does help us if it is a good one. But do not omit |
14250 | the necessary information, such as the test case, on the assumption that | |
14251 | a patch is all we need. We might see problems with your patch and decide | |
14252 | to fix the problem another way, or we might not understand it at all. | |
c4555f82 | 14253 | |
8e04817f AC |
14254 | Sometimes with a program as complicated as @value{GDBN} it is very hard to |
14255 | construct an example that will make the program follow a certain path | |
14256 | through the code. If you do not send us the example, we will not be able | |
14257 | to construct one, so we will not be able to verify that the bug is fixed. | |
c4555f82 | 14258 | |
8e04817f AC |
14259 | And if we cannot understand what bug you are trying to fix, or why your |
14260 | patch should be an improvement, we will not install it. A test case will | |
14261 | help us to understand. | |
c4555f82 | 14262 | |
8e04817f AC |
14263 | @item |
14264 | A guess about what the bug is or what it depends on. | |
c4555f82 | 14265 | |
8e04817f AC |
14266 | Such guesses are usually wrong. Even we cannot guess right about such |
14267 | things without first using the debugger to find the facts. | |
14268 | @end itemize | |
c4555f82 | 14269 | |
8e04817f AC |
14270 | @c The readline documentation is distributed with the readline code |
14271 | @c and consists of the two following files: | |
14272 | @c rluser.texinfo | |
14273 | @c inc-hist.texinfo | |
14274 | @c Use -I with makeinfo to point to the appropriate directory, | |
14275 | @c environment var TEXINPUTS with TeX. | |
14276 | @include rluser.texinfo | |
14277 | @include inc-hist.texinfo | |
c4555f82 | 14278 | |
c4555f82 | 14279 | |
8e04817f AC |
14280 | @node Formatting Documentation |
14281 | @appendix Formatting Documentation | |
c4555f82 | 14282 | |
8e04817f AC |
14283 | @cindex @value{GDBN} reference card |
14284 | @cindex reference card | |
14285 | The @value{GDBN} 4 release includes an already-formatted reference card, ready | |
14286 | for printing with PostScript or Ghostscript, in the @file{gdb} | |
14287 | subdirectory of the main source directory@footnote{In | |
14288 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} | |
14289 | release.}. If you can use PostScript or Ghostscript with your printer, | |
14290 | you can print the reference card immediately with @file{refcard.ps}. | |
c4555f82 | 14291 | |
8e04817f AC |
14292 | The release also includes the source for the reference card. You |
14293 | can format it, using @TeX{}, by typing: | |
c4555f82 | 14294 | |
474c8240 | 14295 | @smallexample |
8e04817f | 14296 | make refcard.dvi |
474c8240 | 14297 | @end smallexample |
c4555f82 | 14298 | |
8e04817f AC |
14299 | The @value{GDBN} reference card is designed to print in @dfn{landscape} |
14300 | mode on US ``letter'' size paper; | |
14301 | that is, on a sheet 11 inches wide by 8.5 inches | |
14302 | high. You will need to specify this form of printing as an option to | |
14303 | your @sc{dvi} output program. | |
c4555f82 | 14304 | |
8e04817f | 14305 | @cindex documentation |
c4555f82 | 14306 | |
8e04817f AC |
14307 | All the documentation for @value{GDBN} comes as part of the machine-readable |
14308 | distribution. The documentation is written in Texinfo format, which is | |
14309 | a documentation system that uses a single source file to produce both | |
14310 | on-line information and a printed manual. You can use one of the Info | |
14311 | formatting commands to create the on-line version of the documentation | |
14312 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. | |
c4555f82 | 14313 | |
8e04817f AC |
14314 | @value{GDBN} includes an already formatted copy of the on-line Info |
14315 | version of this manual in the @file{gdb} subdirectory. The main Info | |
14316 | file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to | |
14317 | subordinate files matching @samp{gdb.info*} in the same directory. If | |
14318 | necessary, you can print out these files, or read them with any editor; | |
14319 | but they are easier to read using the @code{info} subsystem in @sc{gnu} | |
14320 | Emacs or the standalone @code{info} program, available as part of the | |
14321 | @sc{gnu} Texinfo distribution. | |
c4555f82 | 14322 | |
8e04817f AC |
14323 | If you want to format these Info files yourself, you need one of the |
14324 | Info formatting programs, such as @code{texinfo-format-buffer} or | |
14325 | @code{makeinfo}. | |
c4555f82 | 14326 | |
8e04817f AC |
14327 | If you have @code{makeinfo} installed, and are in the top level |
14328 | @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of | |
14329 | version @value{GDBVN}), you can make the Info file by typing: | |
c4555f82 | 14330 | |
474c8240 | 14331 | @smallexample |
8e04817f AC |
14332 | cd gdb |
14333 | make gdb.info | |
474c8240 | 14334 | @end smallexample |
c4555f82 | 14335 | |
8e04817f AC |
14336 | If you want to typeset and print copies of this manual, you need @TeX{}, |
14337 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the | |
14338 | Texinfo definitions file. | |
c4555f82 | 14339 | |
8e04817f AC |
14340 | @TeX{} is a typesetting program; it does not print files directly, but |
14341 | produces output files called @sc{dvi} files. To print a typeset | |
14342 | document, you need a program to print @sc{dvi} files. If your system | |
14343 | has @TeX{} installed, chances are it has such a program. The precise | |
14344 | command to use depends on your system; @kbd{lpr -d} is common; another | |
14345 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may | |
14346 | require a file name without any extension or a @samp{.dvi} extension. | |
c4555f82 | 14347 | |
8e04817f AC |
14348 | @TeX{} also requires a macro definitions file called |
14349 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document | |
14350 | written in Texinfo format. On its own, @TeX{} cannot either read or | |
14351 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB | |
14352 | and is located in the @file{gdb-@var{version-number}/texinfo} | |
14353 | directory. | |
c4555f82 | 14354 | |
8e04817f AC |
14355 | If you have @TeX{} and a @sc{dvi} printer program installed, you can |
14356 | typeset and print this manual. First switch to the the @file{gdb} | |
14357 | subdirectory of the main source directory (for example, to | |
14358 | @file{gdb-@value{GDBVN}/gdb}) and type: | |
c4555f82 | 14359 | |
474c8240 | 14360 | @smallexample |
8e04817f | 14361 | make gdb.dvi |
474c8240 | 14362 | @end smallexample |
c4555f82 | 14363 | |
8e04817f | 14364 | Then give @file{gdb.dvi} to your @sc{dvi} printing program. |
c4555f82 | 14365 | |
8e04817f AC |
14366 | @node Installing GDB |
14367 | @appendix Installing @value{GDBN} | |
14368 | @cindex configuring @value{GDBN} | |
14369 | @cindex installation | |
94e91d6d | 14370 | @cindex configuring @value{GDBN}, and source tree subdirectories |
c4555f82 | 14371 | |
8e04817f AC |
14372 | @value{GDBN} comes with a @code{configure} script that automates the process |
14373 | of preparing @value{GDBN} for installation; you can then use @code{make} to | |
14374 | build the @code{gdb} program. | |
14375 | @iftex | |
14376 | @c irrelevant in info file; it's as current as the code it lives with. | |
14377 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, | |
14378 | look at the @file{README} file in the sources; we may have improved the | |
14379 | installation procedures since publishing this manual.} | |
14380 | @end iftex | |
c4555f82 | 14381 | |
8e04817f AC |
14382 | The @value{GDBN} distribution includes all the source code you need for |
14383 | @value{GDBN} in a single directory, whose name is usually composed by | |
14384 | appending the version number to @samp{gdb}. | |
c4555f82 | 14385 | |
8e04817f AC |
14386 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the |
14387 | @file{gdb-@value{GDBVN}} directory. That directory contains: | |
c4555f82 | 14388 | |
8e04817f AC |
14389 | @table @code |
14390 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} | |
14391 | script for configuring @value{GDBN} and all its supporting libraries | |
c4555f82 | 14392 | |
8e04817f AC |
14393 | @item gdb-@value{GDBVN}/gdb |
14394 | the source specific to @value{GDBN} itself | |
c4555f82 | 14395 | |
8e04817f AC |
14396 | @item gdb-@value{GDBVN}/bfd |
14397 | source for the Binary File Descriptor library | |
c906108c | 14398 | |
8e04817f AC |
14399 | @item gdb-@value{GDBVN}/include |
14400 | @sc{gnu} include files | |
c906108c | 14401 | |
8e04817f AC |
14402 | @item gdb-@value{GDBVN}/libiberty |
14403 | source for the @samp{-liberty} free software library | |
c906108c | 14404 | |
8e04817f AC |
14405 | @item gdb-@value{GDBVN}/opcodes |
14406 | source for the library of opcode tables and disassemblers | |
c906108c | 14407 | |
8e04817f AC |
14408 | @item gdb-@value{GDBVN}/readline |
14409 | source for the @sc{gnu} command-line interface | |
c906108c | 14410 | |
8e04817f AC |
14411 | @item gdb-@value{GDBVN}/glob |
14412 | source for the @sc{gnu} filename pattern-matching subroutine | |
c906108c | 14413 | |
8e04817f AC |
14414 | @item gdb-@value{GDBVN}/mmalloc |
14415 | source for the @sc{gnu} memory-mapped malloc package | |
14416 | @end table | |
c906108c | 14417 | |
8e04817f AC |
14418 | The simplest way to configure and build @value{GDBN} is to run @code{configure} |
14419 | from the @file{gdb-@var{version-number}} source directory, which in | |
14420 | this example is the @file{gdb-@value{GDBVN}} directory. | |
c906108c | 14421 | |
8e04817f AC |
14422 | First switch to the @file{gdb-@var{version-number}} source directory |
14423 | if you are not already in it; then run @code{configure}. Pass the | |
14424 | identifier for the platform on which @value{GDBN} will run as an | |
14425 | argument. | |
c906108c | 14426 | |
8e04817f | 14427 | For example: |
c906108c | 14428 | |
474c8240 | 14429 | @smallexample |
8e04817f AC |
14430 | cd gdb-@value{GDBVN} |
14431 | ./configure @var{host} | |
14432 | make | |
474c8240 | 14433 | @end smallexample |
c906108c | 14434 | |
8e04817f AC |
14435 | @noindent |
14436 | where @var{host} is an identifier such as @samp{sun4} or | |
14437 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. | |
14438 | (You can often leave off @var{host}; @code{configure} tries to guess the | |
14439 | correct value by examining your system.) | |
c906108c | 14440 | |
8e04817f AC |
14441 | Running @samp{configure @var{host}} and then running @code{make} builds the |
14442 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} | |
14443 | libraries, then @code{gdb} itself. The configured source files, and the | |
14444 | binaries, are left in the corresponding source directories. | |
c906108c | 14445 | |
8e04817f AC |
14446 | @need 750 |
14447 | @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your | |
14448 | system does not recognize this automatically when you run a different | |
14449 | shell, you may need to run @code{sh} on it explicitly: | |
c906108c | 14450 | |
474c8240 | 14451 | @smallexample |
8e04817f | 14452 | sh configure @var{host} |
474c8240 | 14453 | @end smallexample |
c906108c | 14454 | |
8e04817f AC |
14455 | If you run @code{configure} from a directory that contains source |
14456 | directories for multiple libraries or programs, such as the | |
14457 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} | |
14458 | creates configuration files for every directory level underneath (unless | |
14459 | you tell it not to, with the @samp{--norecursion} option). | |
14460 | ||
94e91d6d MC |
14461 | You should run the @code{configure} script from the top directory in the |
14462 | source tree, the @file{gdb-@var{version-number}} directory. If you run | |
14463 | @code{configure} from one of the subdirectories, you will configure only | |
14464 | that subdirectory. That is usually not what you want. In particular, | |
14465 | if you run the first @code{configure} from the @file{gdb} subdirectory | |
14466 | of the @file{gdb-@var{version-number}} directory, you will omit the | |
14467 | configuration of @file{bfd}, @file{readline}, and other sibling | |
14468 | directories of the @file{gdb} subdirectory. This leads to build errors | |
14469 | about missing include files such as @file{bfd/bfd.h}. | |
c906108c | 14470 | |
8e04817f AC |
14471 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. |
14472 | However, you should make sure that the shell on your path (named by | |
14473 | the @samp{SHELL} environment variable) is publicly readable. Remember | |
14474 | that @value{GDBN} uses the shell to start your program---some systems refuse to | |
14475 | let @value{GDBN} debug child processes whose programs are not readable. | |
c906108c | 14476 | |
8e04817f AC |
14477 | @menu |
14478 | * Separate Objdir:: Compiling @value{GDBN} in another directory | |
14479 | * Config Names:: Specifying names for hosts and targets | |
14480 | * Configure Options:: Summary of options for configure | |
14481 | @end menu | |
c906108c | 14482 | |
8e04817f AC |
14483 | @node Separate Objdir |
14484 | @section Compiling @value{GDBN} in another directory | |
c906108c | 14485 | |
8e04817f AC |
14486 | If you want to run @value{GDBN} versions for several host or target machines, |
14487 | you need a different @code{gdb} compiled for each combination of | |
14488 | host and target. @code{configure} is designed to make this easy by | |
14489 | allowing you to generate each configuration in a separate subdirectory, | |
14490 | rather than in the source directory. If your @code{make} program | |
14491 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running | |
14492 | @code{make} in each of these directories builds the @code{gdb} | |
14493 | program specified there. | |
c906108c | 14494 | |
8e04817f AC |
14495 | To build @code{gdb} in a separate directory, run @code{configure} |
14496 | with the @samp{--srcdir} option to specify where to find the source. | |
14497 | (You also need to specify a path to find @code{configure} | |
14498 | itself from your working directory. If the path to @code{configure} | |
14499 | would be the same as the argument to @samp{--srcdir}, you can leave out | |
14500 | the @samp{--srcdir} option; it is assumed.) | |
c906108c | 14501 | |
8e04817f AC |
14502 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a |
14503 | separate directory for a Sun 4 like this: | |
c906108c | 14504 | |
474c8240 | 14505 | @smallexample |
8e04817f AC |
14506 | @group |
14507 | cd gdb-@value{GDBVN} | |
14508 | mkdir ../gdb-sun4 | |
14509 | cd ../gdb-sun4 | |
14510 | ../gdb-@value{GDBVN}/configure sun4 | |
14511 | make | |
14512 | @end group | |
474c8240 | 14513 | @end smallexample |
c906108c | 14514 | |
8e04817f AC |
14515 | When @code{configure} builds a configuration using a remote source |
14516 | directory, it creates a tree for the binaries with the same structure | |
14517 | (and using the same names) as the tree under the source directory. In | |
14518 | the example, you'd find the Sun 4 library @file{libiberty.a} in the | |
14519 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in | |
14520 | @file{gdb-sun4/gdb}. | |
c906108c | 14521 | |
94e91d6d MC |
14522 | Make sure that your path to the @file{configure} script has just one |
14523 | instance of @file{gdb} in it. If your path to @file{configure} looks | |
14524 | like @file{../gdb-@value{GDBVN}/gdb/configure}, you are configuring only | |
14525 | one subdirectory of @value{GDBN}, not the whole package. This leads to | |
14526 | build errors about missing include files such as @file{bfd/bfd.h}. | |
14527 | ||
8e04817f AC |
14528 | One popular reason to build several @value{GDBN} configurations in separate |
14529 | directories is to configure @value{GDBN} for cross-compiling (where | |
14530 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging | |
14531 | programs that run on another machine---the @dfn{target}). | |
14532 | You specify a cross-debugging target by | |
14533 | giving the @samp{--target=@var{target}} option to @code{configure}. | |
c906108c | 14534 | |
8e04817f AC |
14535 | When you run @code{make} to build a program or library, you must run |
14536 | it in a configured directory---whatever directory you were in when you | |
14537 | called @code{configure} (or one of its subdirectories). | |
c906108c | 14538 | |
8e04817f AC |
14539 | The @code{Makefile} that @code{configure} generates in each source |
14540 | directory also runs recursively. If you type @code{make} in a source | |
14541 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured | |
14542 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you | |
14543 | will build all the required libraries, and then build GDB. | |
c906108c | 14544 | |
8e04817f AC |
14545 | When you have multiple hosts or targets configured in separate |
14546 | directories, you can run @code{make} on them in parallel (for example, | |
14547 | if they are NFS-mounted on each of the hosts); they will not interfere | |
14548 | with each other. | |
c906108c | 14549 | |
8e04817f AC |
14550 | @node Config Names |
14551 | @section Specifying names for hosts and targets | |
c906108c | 14552 | |
8e04817f AC |
14553 | The specifications used for hosts and targets in the @code{configure} |
14554 | script are based on a three-part naming scheme, but some short predefined | |
14555 | aliases are also supported. The full naming scheme encodes three pieces | |
14556 | of information in the following pattern: | |
c906108c | 14557 | |
474c8240 | 14558 | @smallexample |
8e04817f | 14559 | @var{architecture}-@var{vendor}-@var{os} |
474c8240 | 14560 | @end smallexample |
c906108c | 14561 | |
8e04817f AC |
14562 | For example, you can use the alias @code{sun4} as a @var{host} argument, |
14563 | or as the value for @var{target} in a @code{--target=@var{target}} | |
14564 | option. The equivalent full name is @samp{sparc-sun-sunos4}. | |
c906108c | 14565 | |
8e04817f AC |
14566 | The @code{configure} script accompanying @value{GDBN} does not provide |
14567 | any query facility to list all supported host and target names or | |
14568 | aliases. @code{configure} calls the Bourne shell script | |
14569 | @code{config.sub} to map abbreviations to full names; you can read the | |
14570 | script, if you wish, or you can use it to test your guesses on | |
14571 | abbreviations---for example: | |
c906108c | 14572 | |
8e04817f AC |
14573 | @smallexample |
14574 | % sh config.sub i386-linux | |
14575 | i386-pc-linux-gnu | |
14576 | % sh config.sub alpha-linux | |
14577 | alpha-unknown-linux-gnu | |
14578 | % sh config.sub hp9k700 | |
14579 | hppa1.1-hp-hpux | |
14580 | % sh config.sub sun4 | |
14581 | sparc-sun-sunos4.1.1 | |
14582 | % sh config.sub sun3 | |
14583 | m68k-sun-sunos4.1.1 | |
14584 | % sh config.sub i986v | |
14585 | Invalid configuration `i986v': machine `i986v' not recognized | |
14586 | @end smallexample | |
c906108c | 14587 | |
8e04817f AC |
14588 | @noindent |
14589 | @code{config.sub} is also distributed in the @value{GDBN} source | |
14590 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). | |
d700128c | 14591 | |
8e04817f AC |
14592 | @node Configure Options |
14593 | @section @code{configure} options | |
c906108c | 14594 | |
8e04817f AC |
14595 | Here is a summary of the @code{configure} options and arguments that |
14596 | are most often useful for building @value{GDBN}. @code{configure} also has | |
14597 | several other options not listed here. @inforef{What Configure | |
14598 | Does,,configure.info}, for a full explanation of @code{configure}. | |
c906108c | 14599 | |
474c8240 | 14600 | @smallexample |
8e04817f AC |
14601 | configure @r{[}--help@r{]} |
14602 | @r{[}--prefix=@var{dir}@r{]} | |
14603 | @r{[}--exec-prefix=@var{dir}@r{]} | |
14604 | @r{[}--srcdir=@var{dirname}@r{]} | |
14605 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} | |
14606 | @r{[}--target=@var{target}@r{]} | |
14607 | @var{host} | |
474c8240 | 14608 | @end smallexample |
c906108c | 14609 | |
8e04817f AC |
14610 | @noindent |
14611 | You may introduce options with a single @samp{-} rather than | |
14612 | @samp{--} if you prefer; but you may abbreviate option names if you use | |
14613 | @samp{--}. | |
c906108c | 14614 | |
8e04817f AC |
14615 | @table @code |
14616 | @item --help | |
14617 | Display a quick summary of how to invoke @code{configure}. | |
c906108c | 14618 | |
8e04817f AC |
14619 | @item --prefix=@var{dir} |
14620 | Configure the source to install programs and files under directory | |
14621 | @file{@var{dir}}. | |
c906108c | 14622 | |
8e04817f AC |
14623 | @item --exec-prefix=@var{dir} |
14624 | Configure the source to install programs under directory | |
14625 | @file{@var{dir}}. | |
c906108c | 14626 | |
8e04817f AC |
14627 | @c avoid splitting the warning from the explanation: |
14628 | @need 2000 | |
14629 | @item --srcdir=@var{dirname} | |
14630 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another | |
14631 | @code{make} that implements the @code{VPATH} feature.}@* | |
14632 | Use this option to make configurations in directories separate from the | |
14633 | @value{GDBN} source directories. Among other things, you can use this to | |
14634 | build (or maintain) several configurations simultaneously, in separate | |
14635 | directories. @code{configure} writes configuration specific files in | |
14636 | the current directory, but arranges for them to use the source in the | |
14637 | directory @var{dirname}. @code{configure} creates directories under | |
14638 | the working directory in parallel to the source directories below | |
14639 | @var{dirname}. | |
c906108c | 14640 | |
8e04817f AC |
14641 | @item --norecursion |
14642 | Configure only the directory level where @code{configure} is executed; do not | |
14643 | propagate configuration to subdirectories. | |
c906108c | 14644 | |
8e04817f AC |
14645 | @item --target=@var{target} |
14646 | Configure @value{GDBN} for cross-debugging programs running on the specified | |
14647 | @var{target}. Without this option, @value{GDBN} is configured to debug | |
14648 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. | |
c906108c | 14649 | |
8e04817f | 14650 | There is no convenient way to generate a list of all available targets. |
c906108c | 14651 | |
8e04817f AC |
14652 | @item @var{host} @dots{} |
14653 | Configure @value{GDBN} to run on the specified @var{host}. | |
c906108c | 14654 | |
8e04817f AC |
14655 | There is no convenient way to generate a list of all available hosts. |
14656 | @end table | |
c906108c | 14657 | |
8e04817f AC |
14658 | There are many other options available as well, but they are generally |
14659 | needed for special purposes only. | |
c906108c | 14660 | |
8e04817f AC |
14661 | @node Maintenance Commands |
14662 | @appendix Maintenance Commands | |
14663 | @cindex maintenance commands | |
14664 | @cindex internal commands | |
c906108c | 14665 | |
8e04817f AC |
14666 | In addition to commands intended for @value{GDBN} users, @value{GDBN} |
14667 | includes a number of commands intended for @value{GDBN} developers. | |
14668 | These commands are provided here for reference. | |
c906108c | 14669 | |
8e04817f AC |
14670 | @table @code |
14671 | @kindex maint info breakpoints | |
14672 | @item @anchor{maint info breakpoints}maint info breakpoints | |
14673 | Using the same format as @samp{info breakpoints}, display both the | |
14674 | breakpoints you've set explicitly, and those @value{GDBN} is using for | |
14675 | internal purposes. Internal breakpoints are shown with negative | |
14676 | breakpoint numbers. The type column identifies what kind of breakpoint | |
14677 | is shown: | |
c906108c | 14678 | |
8e04817f AC |
14679 | @table @code |
14680 | @item breakpoint | |
14681 | Normal, explicitly set breakpoint. | |
c906108c | 14682 | |
8e04817f AC |
14683 | @item watchpoint |
14684 | Normal, explicitly set watchpoint. | |
c906108c | 14685 | |
8e04817f AC |
14686 | @item longjmp |
14687 | Internal breakpoint, used to handle correctly stepping through | |
14688 | @code{longjmp} calls. | |
c906108c | 14689 | |
8e04817f AC |
14690 | @item longjmp resume |
14691 | Internal breakpoint at the target of a @code{longjmp}. | |
c906108c | 14692 | |
8e04817f AC |
14693 | @item until |
14694 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. | |
c906108c | 14695 | |
8e04817f AC |
14696 | @item finish |
14697 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. | |
c906108c | 14698 | |
8e04817f AC |
14699 | @item shlib events |
14700 | Shared library events. | |
c906108c | 14701 | |
8e04817f | 14702 | @end table |
c906108c | 14703 | |
8d30a00d AC |
14704 | @kindex maint internal-error |
14705 | @kindex maint internal-warning | |
14706 | @item maint internal-error | |
14707 | @itemx maint internal-warning | |
14708 | Cause @value{GDBN} to call the internal function @code{internal_error} | |
14709 | or @code{internal_warning} and hence behave as though an internal error | |
14710 | or internal warning has been detected. In addition to reporting the | |
14711 | internal problem, these functions give the user the opportunity to | |
14712 | either quit @value{GDBN} or create a core file of the current | |
14713 | @value{GDBN} session. | |
14714 | ||
14715 | @smallexample | |
14716 | (gdb) @kbd{maint internal-error testing, 1, 2} | |
14717 | @dots{}/maint.c:121: internal-error: testing, 1, 2 | |
14718 | A problem internal to GDB has been detected. Further | |
14719 | debugging may prove unreliable. | |
14720 | Quit this debugging session? (y or n) @kbd{n} | |
14721 | Create a core file? (y or n) @kbd{n} | |
14722 | (gdb) | |
14723 | @end smallexample | |
14724 | ||
14725 | Takes an optional parameter that is used as the text of the error or | |
14726 | warning message. | |
14727 | ||
0680b120 AC |
14728 | @kindex maint print registers |
14729 | @kindex maint print raw-registers | |
14730 | @kindex maint print cooked-registers | |
617073a9 | 14731 | @kindex maint print register-groups |
0680b120 AC |
14732 | @item maint print registers |
14733 | @itemx maint print raw-registers | |
14734 | @itemx maint print cooked-registers | |
617073a9 | 14735 | @itemx maint print register-groups |
0680b120 AC |
14736 | Print @value{GDBN}'s internal register data structures. |
14737 | ||
617073a9 AC |
14738 | The command @code{maint print raw-registers} includes the contents of |
14739 | the raw register cache; the command @code{maint print cooked-registers} | |
14740 | includes the (cooked) value of all registers; and the command | |
14741 | @code{maint print register-groups} includes the groups that each | |
14742 | register is a member of. @xref{Registers,, Registers, gdbint, | |
14743 | @value{GDBN} Internals}. | |
0680b120 AC |
14744 | |
14745 | Takes an optional file parameter. | |
14746 | ||
617073a9 AC |
14747 | @kindex maint print reggroups |
14748 | @item maint print reggroups | |
14749 | Print @value{GDBN}'s internal register group data structures. | |
14750 | ||
14751 | Takes an optional file parameter. | |
14752 | ||
14753 | @smallexample | |
14754 | (gdb) @kbd{maint print reggroups} | |
14755 | Group Type | |
14756 | general user | |
14757 | float user | |
14758 | all user | |
14759 | vector user | |
14760 | system user | |
14761 | save internal | |
14762 | restore internal | |
14763 | @end smallexample | |
14764 | ||
e7ba9c65 DJ |
14765 | @kindex maint set profile |
14766 | @kindex maint show profile | |
14767 | @cindex profiling GDB | |
14768 | @item maint set profile | |
14769 | @itemx maint show profile | |
14770 | Control profiling of @value{GDBN}. | |
14771 | ||
14772 | Profiling will be disabled until you use the @samp{maint set profile} | |
14773 | command to enable it. When you enable profiling, the system will begin | |
14774 | collecting timing and execution count data; when you disable profiling or | |
14775 | exit @value{GDBN}, the results will be written to a log file. Remember that | |
14776 | if you use profiling, @value{GDBN} will overwrite the profiling log file | |
14777 | (often called @file{gmon.out}). If you have a record of important profiling | |
14778 | data in a @file{gmon.out} file, be sure to move it to a safe location. | |
14779 | ||
14780 | Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be | |
14781 | compiled with the @samp{-pg} compiler option. | |
14782 | ||
8e04817f | 14783 | @end table |
c906108c | 14784 | |
c906108c | 14785 | |
e0ce93ac | 14786 | @node Remote Protocol |
8e04817f | 14787 | @appendix @value{GDBN} Remote Serial Protocol |
c906108c | 14788 | |
ee2d5c50 AC |
14789 | @menu |
14790 | * Overview:: | |
14791 | * Packets:: | |
14792 | * Stop Reply Packets:: | |
14793 | * General Query Packets:: | |
14794 | * Register Packet Format:: | |
14795 | * Examples:: | |
14796 | @end menu | |
14797 | ||
14798 | @node Overview | |
14799 | @section Overview | |
14800 | ||
8e04817f AC |
14801 | There may be occasions when you need to know something about the |
14802 | protocol---for example, if there is only one serial port to your target | |
14803 | machine, you might want your program to do something special if it | |
14804 | recognizes a packet meant for @value{GDBN}. | |
c906108c | 14805 | |
d2c6833e | 14806 | In the examples below, @samp{->} and @samp{<-} are used to indicate |
8e04817f | 14807 | transmitted and received data respectfully. |
c906108c | 14808 | |
8e04817f AC |
14809 | @cindex protocol, @value{GDBN} remote serial |
14810 | @cindex serial protocol, @value{GDBN} remote | |
14811 | @cindex remote serial protocol | |
14812 | All @value{GDBN} commands and responses (other than acknowledgments) are | |
14813 | sent as a @var{packet}. A @var{packet} is introduced with the character | |
14814 | @samp{$}, the actual @var{packet-data}, and the terminating character | |
14815 | @samp{#} followed by a two-digit @var{checksum}: | |
c906108c | 14816 | |
474c8240 | 14817 | @smallexample |
8e04817f | 14818 | @code{$}@var{packet-data}@code{#}@var{checksum} |
474c8240 | 14819 | @end smallexample |
8e04817f | 14820 | @noindent |
c906108c | 14821 | |
8e04817f AC |
14822 | @cindex checksum, for @value{GDBN} remote |
14823 | @noindent | |
14824 | The two-digit @var{checksum} is computed as the modulo 256 sum of all | |
14825 | characters between the leading @samp{$} and the trailing @samp{#} (an | |
14826 | eight bit unsigned checksum). | |
c906108c | 14827 | |
8e04817f AC |
14828 | Implementors should note that prior to @value{GDBN} 5.0 the protocol |
14829 | specification also included an optional two-digit @var{sequence-id}: | |
c906108c | 14830 | |
474c8240 | 14831 | @smallexample |
8e04817f | 14832 | @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} |
474c8240 | 14833 | @end smallexample |
c906108c | 14834 | |
8e04817f AC |
14835 | @cindex sequence-id, for @value{GDBN} remote |
14836 | @noindent | |
14837 | That @var{sequence-id} was appended to the acknowledgment. @value{GDBN} | |
14838 | has never output @var{sequence-id}s. Stubs that handle packets added | |
14839 | since @value{GDBN} 5.0 must not accept @var{sequence-id}. | |
c906108c | 14840 | |
8e04817f AC |
14841 | @cindex acknowledgment, for @value{GDBN} remote |
14842 | When either the host or the target machine receives a packet, the first | |
14843 | response expected is an acknowledgment: either @samp{+} (to indicate | |
14844 | the package was received correctly) or @samp{-} (to request | |
14845 | retransmission): | |
c906108c | 14846 | |
474c8240 | 14847 | @smallexample |
d2c6833e AC |
14848 | -> @code{$}@var{packet-data}@code{#}@var{checksum} |
14849 | <- @code{+} | |
474c8240 | 14850 | @end smallexample |
8e04817f | 14851 | @noindent |
53a5351d | 14852 | |
8e04817f AC |
14853 | The host (@value{GDBN}) sends @var{command}s, and the target (the |
14854 | debugging stub incorporated in your program) sends a @var{response}. In | |
14855 | the case of step and continue @var{command}s, the response is only sent | |
14856 | when the operation has completed (the target has again stopped). | |
c906108c | 14857 | |
8e04817f AC |
14858 | @var{packet-data} consists of a sequence of characters with the |
14859 | exception of @samp{#} and @samp{$} (see @samp{X} packet for additional | |
14860 | exceptions). | |
c906108c | 14861 | |
8e04817f | 14862 | Fields within the packet should be separated using @samp{,} @samp{;} or |
ee2d5c50 | 14863 | @cindex remote protocol, field separator |
8e04817f | 14864 | @samp{:}. Except where otherwise noted all numbers are represented in |
ee2d5c50 | 14865 | @sc{hex} with leading zeros suppressed. |
c906108c | 14866 | |
8e04817f AC |
14867 | Implementors should note that prior to @value{GDBN} 5.0, the character |
14868 | @samp{:} could not appear as the third character in a packet (as it | |
14869 | would potentially conflict with the @var{sequence-id}). | |
c906108c | 14870 | |
8e04817f AC |
14871 | Response @var{data} can be run-length encoded to save space. A @samp{*} |
14872 | means that the next character is an @sc{ascii} encoding giving a repeat count | |
14873 | which stands for that many repetitions of the character preceding the | |
14874 | @samp{*}. The encoding is @code{n+29}, yielding a printable character | |
14875 | where @code{n >=3} (which is where rle starts to win). The printable | |
14876 | characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric | |
14877 | value greater than 126 should not be used. | |
c906108c | 14878 | |
8e04817f AC |
14879 | Some remote systems have used a different run-length encoding mechanism |
14880 | loosely refered to as the cisco encoding. Following the @samp{*} | |
14881 | character are two hex digits that indicate the size of the packet. | |
c906108c | 14882 | |
8e04817f | 14883 | So: |
474c8240 | 14884 | @smallexample |
8e04817f | 14885 | "@code{0* }" |
474c8240 | 14886 | @end smallexample |
8e04817f AC |
14887 | @noindent |
14888 | means the same as "0000". | |
c906108c | 14889 | |
8e04817f AC |
14890 | The error response returned for some packets includes a two character |
14891 | error number. That number is not well defined. | |
c906108c | 14892 | |
8e04817f AC |
14893 | For any @var{command} not supported by the stub, an empty response |
14894 | (@samp{$#00}) should be returned. That way it is possible to extend the | |
14895 | protocol. A newer @value{GDBN} can tell if a packet is supported based | |
14896 | on that response. | |
c906108c | 14897 | |
8e04817f AC |
14898 | A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M}, |
14899 | @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are | |
14900 | optional. | |
c906108c | 14901 | |
ee2d5c50 AC |
14902 | @node Packets |
14903 | @section Packets | |
14904 | ||
14905 | The following table provides a complete list of all currently defined | |
14906 | @var{command}s and their corresponding response @var{data}. | |
14907 | ||
14908 | @table @r | |
14909 | ||
14910 | @item @code{!} --- extended mode | |
14911 | @cindex @code{!} packet | |
14912 | ||
8e04817f AC |
14913 | Enable extended mode. In extended mode, the remote server is made |
14914 | persistent. The @samp{R} packet is used to restart the program being | |
14915 | debugged. | |
ee2d5c50 AC |
14916 | |
14917 | Reply: | |
14918 | @table @samp | |
14919 | @item OK | |
8e04817f | 14920 | The remote target both supports and has enabled extended mode. |
ee2d5c50 | 14921 | @end table |
c906108c | 14922 | |
ee2d5c50 AC |
14923 | @item @code{?} --- last signal |
14924 | @cindex @code{?} packet | |
c906108c | 14925 | |
ee2d5c50 AC |
14926 | Indicate the reason the target halted. The reply is the same as for |
14927 | step and continue. | |
c906108c | 14928 | |
ee2d5c50 AC |
14929 | Reply: |
14930 | @xref{Stop Reply Packets}, for the reply specifications. | |
14931 | ||
14932 | @item @code{a} --- reserved | |
14933 | ||
14934 | Reserved for future use. | |
14935 | ||
14936 | @item @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,@dots{}} --- set program arguments @strong{(reserved)} | |
14937 | @cindex @code{A} packet | |
c906108c | 14938 | |
8e04817f AC |
14939 | Initialized @samp{argv[]} array passed into program. @var{arglen} |
14940 | specifies the number of bytes in the hex encoded byte stream @var{arg}. | |
ee2d5c50 AC |
14941 | See @code{gdbserver} for more details. |
14942 | ||
14943 | Reply: | |
14944 | @table @samp | |
14945 | @item OK | |
14946 | @item E@var{NN} | |
14947 | @end table | |
14948 | ||
14949 | @item @code{b}@var{baud} --- set baud @strong{(deprecated)} | |
14950 | @cindex @code{b} packet | |
14951 | ||
14952 | Change the serial line speed to @var{baud}. | |
14953 | ||
14954 | JTC: @emph{When does the transport layer state change? When it's | |
14955 | received, or after the ACK is transmitted. In either case, there are | |
14956 | problems if the command or the acknowledgment packet is dropped.} | |
14957 | ||
14958 | Stan: @emph{If people really wanted to add something like this, and get | |
14959 | it working for the first time, they ought to modify ser-unix.c to send | |
14960 | some kind of out-of-band message to a specially-setup stub and have the | |
14961 | switch happen "in between" packets, so that from remote protocol's point | |
14962 | of view, nothing actually happened.} | |
14963 | ||
14964 | @item @code{B}@var{addr},@var{mode} --- set breakpoint @strong{(deprecated)} | |
14965 | @cindex @code{B} packet | |
14966 | ||
8e04817f | 14967 | Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a |
2f870471 AC |
14968 | breakpoint at @var{addr}. |
14969 | ||
14970 | This packet has been replaced by the @samp{Z} and @samp{z} packets | |
14971 | (@pxref{insert breakpoint or watchpoint packet}). | |
c906108c | 14972 | |
ee2d5c50 AC |
14973 | @item @code{c}@var{addr} --- continue |
14974 | @cindex @code{c} packet | |
14975 | ||
14976 | @var{addr} is address to resume. If @var{addr} is omitted, resume at | |
8e04817f | 14977 | current address. |
c906108c | 14978 | |
ee2d5c50 AC |
14979 | Reply: |
14980 | @xref{Stop Reply Packets}, for the reply specifications. | |
14981 | ||
14982 | @item @code{C}@var{sig}@code{;}@var{addr} --- continue with signal | |
14983 | @cindex @code{C} packet | |
14984 | ||
8e04817f AC |
14985 | Continue with signal @var{sig} (hex signal number). If |
14986 | @code{;}@var{addr} is omitted, resume at same address. | |
c906108c | 14987 | |
ee2d5c50 AC |
14988 | Reply: |
14989 | @xref{Stop Reply Packets}, for the reply specifications. | |
c906108c | 14990 | |
ee2d5c50 AC |
14991 | @item @code{d} --- toggle debug @strong{(deprecated)} |
14992 | @cindex @code{d} packet | |
14993 | ||
14994 | Toggle debug flag. | |
14995 | ||
14996 | @item @code{D} --- detach | |
14997 | @cindex @code{D} packet | |
14998 | ||
14999 | Detach @value{GDBN} from the remote system. Sent to the remote target | |
15000 | before @value{GDBN} disconnects. | |
15001 | ||
15002 | Reply: | |
15003 | @table @samp | |
15004 | @item @emph{no response} | |
8e04817f | 15005 | @value{GDBN} does not check for any response after sending this packet. |
ee2d5c50 | 15006 | @end table |
c906108c | 15007 | |
ee2d5c50 | 15008 | @item @code{e} --- reserved |
c906108c | 15009 | |
ee2d5c50 | 15010 | Reserved for future use. |
c906108c | 15011 | |
ee2d5c50 | 15012 | @item @code{E} --- reserved |
c906108c | 15013 | |
ee2d5c50 | 15014 | Reserved for future use. |
c906108c | 15015 | |
ee2d5c50 AC |
15016 | @item @code{f} --- reserved |
15017 | ||
15018 | Reserved for future use. | |
15019 | ||
15020 | @item @code{F} --- reserved | |
15021 | ||
15022 | Reserved for future use. | |
15023 | ||
15024 | @item @code{g} --- read registers | |
15025 | @anchor{read registers packet} | |
15026 | @cindex @code{g} packet | |
15027 | ||
15028 | Read general registers. | |
15029 | ||
15030 | Reply: | |
15031 | @table @samp | |
15032 | @item @var{XX@dots{}} | |
8e04817f AC |
15033 | Each byte of register data is described by two hex digits. The bytes |
15034 | with the register are transmitted in target byte order. The size of | |
15035 | each register and their position within the @samp{g} @var{packet} are | |
ee2d5c50 AC |
15036 | determined by the @value{GDBN} internal macros @var{REGISTER_RAW_SIZE} |
15037 | and @var{REGISTER_NAME} macros. The specification of several standard | |
8e04817f | 15038 | @code{g} packets is specified below. |
ee2d5c50 AC |
15039 | @item E@var{NN} |
15040 | for an error. | |
15041 | @end table | |
c906108c | 15042 | |
ee2d5c50 AC |
15043 | @item @code{G}@var{XX@dots{}} --- write regs |
15044 | @cindex @code{G} packet | |
c906108c | 15045 | |
ee2d5c50 AC |
15046 | @xref{read registers packet}, for a description of the @var{XX@dots{}} |
15047 | data. | |
15048 | ||
15049 | Reply: | |
15050 | @table @samp | |
15051 | @item OK | |
15052 | for success | |
15053 | @item E@var{NN} | |
15054 | for an error | |
15055 | @end table | |
15056 | ||
15057 | @item @code{h} --- reserved | |
15058 | ||
15059 | Reserved for future use. | |
15060 | ||
15061 | @item @code{H}@var{c}@var{t@dots{}} --- set thread | |
15062 | @cindex @code{H} packet | |
c906108c | 15063 | |
8e04817f | 15064 | Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, |
ee2d5c50 AC |
15065 | @samp{G}, et.al.). @var{c} depends on the operation to be performed: it |
15066 | should be @samp{c} for step and continue operations, @samp{g} for other | |
15067 | operations. The thread designator @var{t@dots{}} may be -1, meaning all | |
15068 | the threads, a thread number, or zero which means pick any thread. | |
15069 | ||
15070 | Reply: | |
15071 | @table @samp | |
15072 | @item OK | |
15073 | for success | |
15074 | @item E@var{NN} | |
15075 | for an error | |
15076 | @end table | |
c906108c | 15077 | |
8e04817f AC |
15078 | @c FIXME: JTC: |
15079 | @c 'H': How restrictive (or permissive) is the thread model. If a | |
15080 | @c thread is selected and stopped, are other threads allowed | |
15081 | @c to continue to execute? As I mentioned above, I think the | |
15082 | @c semantics of each command when a thread is selected must be | |
15083 | @c described. For example: | |
15084 | @c | |
15085 | @c 'g': If the stub supports threads and a specific thread is | |
15086 | @c selected, returns the register block from that thread; | |
15087 | @c otherwise returns current registers. | |
15088 | @c | |
15089 | @c 'G' If the stub supports threads and a specific thread is | |
15090 | @c selected, sets the registers of the register block of | |
15091 | @c that thread; otherwise sets current registers. | |
c906108c | 15092 | |
ee2d5c50 AC |
15093 | @item @code{i}@var{addr}@code{,}@var{nnn} --- cycle step @strong{(draft)} |
15094 | @anchor{cycle step packet} | |
15095 | @cindex @code{i} packet | |
15096 | ||
8e04817f AC |
15097 | Step the remote target by a single clock cycle. If @code{,}@var{nnn} is |
15098 | present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle | |
15099 | step starting at that address. | |
c906108c | 15100 | |
ee2d5c50 AC |
15101 | @item @code{I} --- signal then cycle step @strong{(reserved)} |
15102 | @cindex @code{I} packet | |
15103 | ||
15104 | @xref{step with signal packet}. @xref{cycle step packet}. | |
15105 | ||
15106 | @item @code{j} --- reserved | |
15107 | ||
15108 | Reserved for future use. | |
15109 | ||
15110 | @item @code{J} --- reserved | |
c906108c | 15111 | |
ee2d5c50 | 15112 | Reserved for future use. |
c906108c | 15113 | |
ee2d5c50 AC |
15114 | @item @code{k} --- kill request |
15115 | @cindex @code{k} packet | |
c906108c | 15116 | |
ac282366 | 15117 | FIXME: @emph{There is no description of how to operate when a specific |
ee2d5c50 AC |
15118 | thread context has been selected (i.e.@: does 'k' kill only that |
15119 | thread?)}. | |
c906108c | 15120 | |
ee2d5c50 | 15121 | @item @code{K} --- reserved |
c906108c | 15122 | |
ee2d5c50 AC |
15123 | Reserved for future use. |
15124 | ||
15125 | @item @code{l} --- reserved | |
15126 | ||
15127 | Reserved for future use. | |
15128 | ||
15129 | @item @code{L} --- reserved | |
15130 | ||
15131 | Reserved for future use. | |
15132 | ||
15133 | @item @code{m}@var{addr}@code{,}@var{length} --- read memory | |
15134 | @cindex @code{m} packet | |
c906108c | 15135 | |
8e04817f | 15136 | Read @var{length} bytes of memory starting at address @var{addr}. |
ee2d5c50 | 15137 | Neither @value{GDBN} nor the stub assume that sized memory transfers are |
2e834e49 | 15138 | assumed using word aligned accesses. FIXME: @emph{A word aligned memory |
8e04817f | 15139 | transfer mechanism is needed.} |
c906108c | 15140 | |
ee2d5c50 AC |
15141 | Reply: |
15142 | @table @samp | |
15143 | @item @var{XX@dots{}} | |
15144 | @var{XX@dots{}} is mem contents. Can be fewer bytes than requested if able | |
15145 | to read only part of the data. Neither @value{GDBN} nor the stub assume | |
2e834e49 | 15146 | that sized memory transfers are assumed using word aligned |
ee2d5c50 AC |
15147 | accesses. FIXME: @emph{A word aligned memory transfer mechanism is |
15148 | needed.} | |
15149 | @item E@var{NN} | |
15150 | @var{NN} is errno | |
15151 | @end table | |
15152 | ||
15153 | @item @code{M}@var{addr},@var{length}@code{:}@var{XX@dots{}} --- write mem | |
15154 | @cindex @code{M} packet | |
15155 | ||
8e04817f | 15156 | Write @var{length} bytes of memory starting at address @var{addr}. |
ee2d5c50 AC |
15157 | @var{XX@dots{}} is the data. |
15158 | ||
15159 | Reply: | |
15160 | @table @samp | |
15161 | @item OK | |
15162 | for success | |
15163 | @item E@var{NN} | |
8e04817f AC |
15164 | for an error (this includes the case where only part of the data was |
15165 | written). | |
ee2d5c50 | 15166 | @end table |
c906108c | 15167 | |
ee2d5c50 | 15168 | @item @code{n} --- reserved |
c906108c | 15169 | |
ee2d5c50 | 15170 | Reserved for future use. |
c906108c | 15171 | |
ee2d5c50 | 15172 | @item @code{N} --- reserved |
c906108c | 15173 | |
ee2d5c50 | 15174 | Reserved for future use. |
c906108c | 15175 | |
ee2d5c50 AC |
15176 | @item @code{o} --- reserved |
15177 | ||
15178 | Reserved for future use. | |
15179 | ||
15180 | @item @code{O} --- reserved | |
15181 | ||
15182 | Reserved for future use. | |
c906108c | 15183 | |
ee2d5c50 AC |
15184 | @item @code{p}@var{n@dots{}} --- read reg @strong{(reserved)} |
15185 | @cindex @code{p} packet | |
15186 | ||
15187 | @xref{write register packet}. | |
15188 | ||
15189 | Reply: | |
15190 | @table @samp | |
15191 | @item @var{r@dots{}.} | |
15192 | The hex encoded value of the register in target byte order. | |
15193 | @end table | |
15194 | ||
15195 | @item @code{P}@var{n@dots{}}@code{=}@var{r@dots{}} --- write register | |
15196 | @anchor{write register packet} | |
15197 | @cindex @code{P} packet | |
15198 | ||
15199 | Write register @var{n@dots{}} with value @var{r@dots{}}, which contains two hex | |
8e04817f | 15200 | digits for each byte in the register (target byte order). |
c906108c | 15201 | |
ee2d5c50 AC |
15202 | Reply: |
15203 | @table @samp | |
15204 | @item OK | |
15205 | for success | |
15206 | @item E@var{NN} | |
15207 | for an error | |
15208 | @end table | |
15209 | ||
15210 | @item @code{q}@var{query} --- general query | |
15211 | @anchor{general query packet} | |
15212 | @cindex @code{q} packet | |
15213 | ||
15214 | Request info about @var{query}. In general @value{GDBN} queries have a | |
15215 | leading upper case letter. Custom vendor queries should use a company | |
15216 | prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may optionally | |
15217 | be followed by a @samp{,} or @samp{;} separated list. Stubs must ensure | |
15218 | that they match the full @var{query} name. | |
15219 | ||
15220 | Reply: | |
15221 | @table @samp | |
15222 | @item @var{XX@dots{}} | |
15223 | Hex encoded data from query. The reply can not be empty. | |
15224 | @item E@var{NN} | |
15225 | error reply | |
8e04817f | 15226 | @item |
ee2d5c50 AC |
15227 | Indicating an unrecognized @var{query}. |
15228 | @end table | |
15229 | ||
15230 | @item @code{Q}@var{var}@code{=}@var{val} --- general set | |
15231 | @cindex @code{Q} packet | |
15232 | ||
15233 | Set value of @var{var} to @var{val}. | |
15234 | ||
15235 | @xref{general query packet}, for a discussion of naming conventions. | |
c906108c | 15236 | |
ee2d5c50 AC |
15237 | @item @code{r} --- reset @strong{(deprecated)} |
15238 | @cindex @code{r} packet | |
c906108c | 15239 | |
8e04817f | 15240 | Reset the entire system. |
c906108c | 15241 | |
ee2d5c50 AC |
15242 | @item @code{R}@var{XX} --- remote restart |
15243 | @cindex @code{R} packet | |
15244 | ||
8e04817f AC |
15245 | Restart the program being debugged. @var{XX}, while needed, is ignored. |
15246 | This packet is only available in extended mode. | |
ee2d5c50 AC |
15247 | |
15248 | Reply: | |
15249 | @table @samp | |
15250 | @item @emph{no reply} | |
8e04817f | 15251 | The @samp{R} packet has no reply. |
ee2d5c50 AC |
15252 | @end table |
15253 | ||
15254 | @item @code{s}@var{addr} --- step | |
15255 | @cindex @code{s} packet | |
c906108c | 15256 | |
8e04817f AC |
15257 | @var{addr} is address to resume. If @var{addr} is omitted, resume at |
15258 | same address. | |
c906108c | 15259 | |
ee2d5c50 AC |
15260 | Reply: |
15261 | @xref{Stop Reply Packets}, for the reply specifications. | |
15262 | ||
15263 | @item @code{S}@var{sig}@code{;}@var{addr} --- step with signal | |
15264 | @anchor{step with signal packet} | |
15265 | @cindex @code{S} packet | |
15266 | ||
8e04817f | 15267 | Like @samp{C} but step not continue. |
c906108c | 15268 | |
ee2d5c50 AC |
15269 | Reply: |
15270 | @xref{Stop Reply Packets}, for the reply specifications. | |
15271 | ||
15272 | @item @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} --- search | |
15273 | @cindex @code{t} packet | |
15274 | ||
8e04817f | 15275 | Search backwards starting at address @var{addr} for a match with pattern |
ee2d5c50 AC |
15276 | @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes. |
15277 | @var{addr} must be at least 3 digits. | |
c906108c | 15278 | |
ee2d5c50 AC |
15279 | @item @code{T}@var{XX} --- thread alive |
15280 | @cindex @code{T} packet | |
c906108c | 15281 | |
ee2d5c50 | 15282 | Find out if the thread XX is alive. |
c906108c | 15283 | |
ee2d5c50 AC |
15284 | Reply: |
15285 | @table @samp | |
15286 | @item OK | |
15287 | thread is still alive | |
15288 | @item E@var{NN} | |
15289 | thread is dead | |
15290 | @end table | |
15291 | ||
15292 | @item @code{u} --- reserved | |
15293 | ||
15294 | Reserved for future use. | |
15295 | ||
15296 | @item @code{U} --- reserved | |
15297 | ||
15298 | Reserved for future use. | |
15299 | ||
15300 | @item @code{v} --- reserved | |
15301 | ||
15302 | Reserved for future use. | |
15303 | ||
15304 | @item @code{V} --- reserved | |
c906108c | 15305 | |
ee2d5c50 | 15306 | Reserved for future use. |
c906108c | 15307 | |
ee2d5c50 | 15308 | @item @code{w} --- reserved |
c906108c | 15309 | |
ee2d5c50 | 15310 | Reserved for future use. |
c906108c | 15311 | |
ee2d5c50 | 15312 | @item @code{W} --- reserved |
c906108c | 15313 | |
ee2d5c50 | 15314 | Reserved for future use. |
c906108c | 15315 | |
ee2d5c50 AC |
15316 | @item @code{x} --- reserved |
15317 | ||
15318 | Reserved for future use. | |
15319 | ||
15320 | @item @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX@dots{}} --- write mem (binary) | |
15321 | @cindex @code{X} packet | |
15322 | ||
15323 | @var{addr} is address, @var{length} is number of bytes, @var{XX@dots{}} | |
15324 | is binary data. The characters @code{$}, @code{#}, and @code{0x7d} are | |
8e04817f | 15325 | escaped using @code{0x7d}. |
c906108c | 15326 | |
ee2d5c50 AC |
15327 | Reply: |
15328 | @table @samp | |
15329 | @item OK | |
15330 | for success | |
15331 | @item E@var{NN} | |
15332 | for an error | |
15333 | @end table | |
15334 | ||
15335 | @item @code{y} --- reserved | |
c906108c | 15336 | |
ee2d5c50 | 15337 | Reserved for future use. |
c906108c | 15338 | |
ee2d5c50 AC |
15339 | @item @code{Y} reserved |
15340 | ||
15341 | Reserved for future use. | |
15342 | ||
2f870471 AC |
15343 | @item @code{z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- remove breakpoint or watchpoint @strong{(draft)} |
15344 | @itemx @code{Z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- insert breakpoint or watchpoint @strong{(draft)} | |
15345 | @anchor{insert breakpoint or watchpoint packet} | |
ee2d5c50 | 15346 | @cindex @code{z} packet |
2f870471 | 15347 | @cindex @code{Z} packets |
ee2d5c50 | 15348 | |
2f870471 AC |
15349 | Insert (@code{Z}) or remove (@code{z}) a @var{type} breakpoint or |
15350 | watchpoint starting at address @var{address} and covering the next | |
15351 | @var{length} bytes. | |
ee2d5c50 | 15352 | |
2f870471 AC |
15353 | Each breakpoint and watchpoint packet @var{type} is documented |
15354 | separately. | |
15355 | ||
512217c7 AC |
15356 | @emph{Implementation notes: A remote target shall return an empty string |
15357 | for an unrecognized breakpoint or watchpoint packet @var{type}. A | |
15358 | remote target shall support either both or neither of a given | |
2f870471 AC |
15359 | @code{Z}@var{type}@dots{} and @code{z}@var{type}@dots{} packet pair. To |
15360 | avoid potential problems with duplicate packets, the operations should | |
15361 | be implemented in an idempotent way.} | |
15362 | ||
15363 | @item @code{z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- remove memory breakpoint @strong{(draft)} | |
15364 | @item @code{Z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- insert memory breakpoint @strong{(draft)} | |
15365 | @cindex @code{z0} packet | |
15366 | @cindex @code{Z0} packet | |
15367 | ||
15368 | Insert (@code{Z0}) or remove (@code{z0}) a memory breakpoint at address | |
15369 | @code{addr} of size @code{length}. | |
15370 | ||
15371 | A memory breakpoint is implemented by replacing the instruction at | |
15372 | @var{addr} with a software breakpoint or trap instruction. The | |
15373 | @code{length} is used by targets that indicates the size of the | |
15374 | breakpoint (in bytes) that should be inserted (e.g., the @sc{arm} and | |
15375 | @sc{mips} can insert either a 2 or 4 byte breakpoint). | |
c906108c | 15376 | |
2f870471 AC |
15377 | @emph{Implementation note: It is possible for a target to copy or move |
15378 | code that contains memory breakpoints (e.g., when implementing | |
15379 | overlays). The behavior of this packet, in the presence of such a | |
15380 | target, is not defined.} | |
c906108c | 15381 | |
ee2d5c50 AC |
15382 | Reply: |
15383 | @table @samp | |
2f870471 AC |
15384 | @item OK |
15385 | success | |
15386 | @item | |
15387 | not supported | |
ee2d5c50 AC |
15388 | @item E@var{NN} |
15389 | for an error | |
2f870471 AC |
15390 | @end table |
15391 | ||
15392 | @item @code{z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- remove hardware breakpoint @strong{(draft)} | |
15393 | @item @code{Z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- insert hardware breakpoint @strong{(draft)} | |
15394 | @cindex @code{z1} packet | |
15395 | @cindex @code{Z1} packet | |
15396 | ||
15397 | Insert (@code{Z1}) or remove (@code{z1}) a hardware breakpoint at | |
15398 | address @code{addr} of size @code{length}. | |
15399 | ||
15400 | A hardware breakpoint is implemented using a mechanism that is not | |
15401 | dependant on being able to modify the target's memory. | |
15402 | ||
15403 | @emph{Implementation note: A hardware breakpoint is not affected by code | |
15404 | movement.} | |
15405 | ||
15406 | Reply: | |
15407 | @table @samp | |
ee2d5c50 | 15408 | @item OK |
2f870471 AC |
15409 | success |
15410 | @item | |
15411 | not supported | |
15412 | @item E@var{NN} | |
15413 | for an error | |
15414 | @end table | |
15415 | ||
15416 | @item @code{z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- remove write watchpoint @strong{(draft)} | |
15417 | @item @code{Z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- insert write watchpoint @strong{(draft)} | |
15418 | @cindex @code{z2} packet | |
15419 | @cindex @code{Z2} packet | |
15420 | ||
15421 | Insert (@code{Z2}) or remove (@code{z2}) a write watchpoint. | |
15422 | ||
15423 | Reply: | |
15424 | @table @samp | |
15425 | @item OK | |
15426 | success | |
15427 | @item | |
15428 | not supported | |
15429 | @item E@var{NN} | |
15430 | for an error | |
15431 | @end table | |
15432 | ||
15433 | @item @code{z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- remove read watchpoint @strong{(draft)} | |
15434 | @item @code{Z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- insert read watchpoint @strong{(draft)} | |
15435 | @cindex @code{z3} packet | |
15436 | @cindex @code{Z3} packet | |
15437 | ||
2e834e49 | 15438 | Insert (@code{Z3}) or remove (@code{z3}) a read watchpoint. |
2f870471 AC |
15439 | |
15440 | Reply: | |
15441 | @table @samp | |
15442 | @item OK | |
15443 | success | |
15444 | @item | |
15445 | not supported | |
15446 | @item E@var{NN} | |
15447 | for an error | |
15448 | @end table | |
15449 | ||
2e834e49 HPN |
15450 | @item @code{z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- remove access watchpoint @strong{(draft)} |
15451 | @item @code{Z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- insert access watchpoint @strong{(draft)} | |
2f870471 AC |
15452 | @cindex @code{z4} packet |
15453 | @cindex @code{Z4} packet | |
15454 | ||
15455 | Insert (@code{Z4}) or remove (@code{z4}) an access watchpoint. | |
15456 | ||
15457 | Reply: | |
15458 | @table @samp | |
15459 | @item OK | |
15460 | success | |
15461 | @item | |
15462 | not supported | |
15463 | @item E@var{NN} | |
15464 | for an error | |
ee2d5c50 AC |
15465 | @end table |
15466 | ||
15467 | @end table | |
c906108c | 15468 | |
ee2d5c50 AC |
15469 | @node Stop Reply Packets |
15470 | @section Stop Reply Packets | |
15471 | @cindex stop reply packets | |
c906108c | 15472 | |
8e04817f AC |
15473 | The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can |
15474 | receive any of the below as a reply. In the case of the @samp{C}, | |
15475 | @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned | |
15476 | when the target halts. In the below the exact meaning of @samp{signal | |
15477 | number} is poorly defined. In general one of the UNIX signal numbering | |
15478 | conventions is used. | |
c906108c | 15479 | |
ee2d5c50 | 15480 | @table @samp |
c906108c | 15481 | |
ee2d5c50 AC |
15482 | @item S@var{AA} |
15483 | @var{AA} is the signal number | |
c906108c | 15484 | |
8e04817f | 15485 | @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;} |
ee2d5c50 AC |
15486 | @cindex @code{T} packet reply |
15487 | ||
8e04817f AC |
15488 | @var{AA} = two hex digit signal number; @var{n...} = register number |
15489 | (hex), @var{r...} = target byte ordered register contents, size defined | |
15490 | by @code{REGISTER_RAW_SIZE}; @var{n...} = @samp{thread}, @var{r...} = | |
3c3bea1c GS |
15491 | thread process ID, this is a hex integer; @var{n...} = (@samp{watch} | |
15492 | @samp{rwatch} | @samp{awatch}, @var{r...} = data address, this is a hex | |
15493 | integer; @var{n...} = other string not starting with valid hex digit. | |
15494 | @value{GDBN} should ignore this @var{n...}, @var{r...} pair and go on | |
15495 | to the next. This way we can extend the protocol. | |
c906108c | 15496 | |
ee2d5c50 AC |
15497 | @item W@var{AA} |
15498 | ||
8e04817f | 15499 | The process exited, and @var{AA} is the exit status. This is only |
ee2d5c50 AC |
15500 | applicable to certain targets. |
15501 | ||
15502 | @item X@var{AA} | |
c906108c | 15503 | |
8e04817f | 15504 | The process terminated with signal @var{AA}. |
c906108c | 15505 | |
ee2d5c50 AC |
15506 | @item N@var{AA};@var{t@dots{}};@var{d@dots{}};@var{b@dots{}} @strong{(obsolete)} |
15507 | ||
15508 | @var{AA} = signal number; @var{t@dots{}} = address of symbol | |
15509 | @code{_start}; @var{d@dots{}} = base of data section; @var{b@dots{}} = | |
15510 | base of bss section. @emph{Note: only used by Cisco Systems targets. | |
15511 | The difference between this reply and the @samp{qOffsets} query is that | |
15512 | the @samp{N} packet may arrive spontaneously whereas the @samp{qOffsets} | |
15513 | is a query initiated by the host debugger.} | |
c906108c | 15514 | |
ee2d5c50 | 15515 | @item O@var{XX@dots{}} |
c906108c | 15516 | |
ee2d5c50 AC |
15517 | @var{XX@dots{}} is hex encoding of @sc{ascii} data. This can happen at |
15518 | any time while the program is running and the debugger should continue | |
15519 | to wait for @samp{W}, @samp{T}, etc. | |
15520 | ||
15521 | @end table | |
15522 | ||
15523 | @node General Query Packets | |
15524 | @section General Query Packets | |
c906108c | 15525 | |
8e04817f | 15526 | The following set and query packets have already been defined. |
c906108c | 15527 | |
ee2d5c50 | 15528 | @table @r |
c906108c | 15529 | |
ee2d5c50 AC |
15530 | @item @code{q}@code{C} --- current thread |
15531 | ||
15532 | Return the current thread id. | |
15533 | ||
15534 | Reply: | |
15535 | @table @samp | |
15536 | @item @code{QC}@var{pid} | |
8e04817f | 15537 | Where @var{pid} is a HEX encoded 16 bit process id. |
ee2d5c50 AC |
15538 | @item * |
15539 | Any other reply implies the old pid. | |
15540 | @end table | |
15541 | ||
15542 | @item @code{q}@code{fThreadInfo} -- all thread ids | |
15543 | ||
15544 | @code{q}@code{sThreadInfo} | |
c906108c | 15545 | |
8e04817f AC |
15546 | Obtain a list of active thread ids from the target (OS). Since there |
15547 | may be too many active threads to fit into one reply packet, this query | |
15548 | works iteratively: it may require more than one query/reply sequence to | |
15549 | obtain the entire list of threads. The first query of the sequence will | |
15550 | be the @code{qf}@code{ThreadInfo} query; subsequent queries in the | |
15551 | sequence will be the @code{qs}@code{ThreadInfo} query. | |
ee2d5c50 AC |
15552 | |
15553 | NOTE: replaces the @code{qL} query (see below). | |
15554 | ||
15555 | Reply: | |
15556 | @table @samp | |
15557 | @item @code{m}@var{id} | |
15558 | A single thread id | |
15559 | @item @code{m}@var{id},@var{id}@dots{} | |
15560 | a comma-separated list of thread ids | |
15561 | @item @code{l} | |
15562 | (lower case 'el') denotes end of list. | |
15563 | @end table | |
15564 | ||
15565 | In response to each query, the target will reply with a list of one or | |
15566 | more thread ids, in big-endian hex, separated by commas. @value{GDBN} | |
15567 | will respond to each reply with a request for more thread ids (using the | |
8e04817f AC |
15568 | @code{qs} form of the query), until the target responds with @code{l} |
15569 | (lower-case el, for @code{'last'}). | |
c906108c | 15570 | |
ee2d5c50 AC |
15571 | @item @code{q}@code{ThreadExtraInfo}@code{,}@var{id} --- extra thread info |
15572 | ||
15573 | Where @var{id} is a thread-id in big-endian hex. Obtain a printable | |
15574 | string description of a thread's attributes from the target OS. This | |
15575 | string may contain anything that the target OS thinks is interesting for | |
15576 | @value{GDBN} to tell the user about the thread. The string is displayed | |
15577 | in @value{GDBN}'s @samp{info threads} display. Some examples of | |
15578 | possible thread extra info strings are ``Runnable'', or ``Blocked on | |
15579 | Mutex''. | |
15580 | ||
15581 | Reply: | |
15582 | @table @samp | |
15583 | @item @var{XX@dots{}} | |
15584 | Where @var{XX@dots{}} is a hex encoding of @sc{ascii} data, comprising | |
15585 | the printable string containing the extra information about the thread's | |
8e04817f | 15586 | attributes. |
ee2d5c50 AC |
15587 | @end table |
15588 | ||
15589 | @item @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} --- query @var{LIST} or @var{threadLIST} @strong{(deprecated)} | |
c906108c | 15590 | |
8e04817f AC |
15591 | Obtain thread information from RTOS. Where: @var{startflag} (one hex |
15592 | digit) is one to indicate the first query and zero to indicate a | |
15593 | subsequent query; @var{threadcount} (two hex digits) is the maximum | |
15594 | number of threads the response packet can contain; and @var{nextthread} | |
15595 | (eight hex digits), for subsequent queries (@var{startflag} is zero), is | |
15596 | returned in the response as @var{argthread}. | |
ee2d5c50 AC |
15597 | |
15598 | NOTE: this query is replaced by the @code{q}@code{fThreadInfo} query | |
15599 | (see above). | |
15600 | ||
15601 | Reply: | |
15602 | @table @samp | |
15603 | @item @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread@dots{}} | |
8e04817f AC |
15604 | Where: @var{count} (two hex digits) is the number of threads being |
15605 | returned; @var{done} (one hex digit) is zero to indicate more threads | |
15606 | and one indicates no further threads; @var{argthreadid} (eight hex | |
ee2d5c50 AC |
15607 | digits) is @var{nextthread} from the request packet; @var{thread@dots{}} |
15608 | is a sequence of thread IDs from the target. @var{threadid} (eight hex | |
8e04817f | 15609 | digits). See @code{remote.c:parse_threadlist_response()}. |
ee2d5c50 | 15610 | @end table |
c906108c | 15611 | |
ee2d5c50 AC |
15612 | @item @code{q}@code{CRC:}@var{addr}@code{,}@var{length} --- compute CRC of memory block |
15613 | ||
15614 | Reply: | |
15615 | @table @samp | |
15616 | @item @code{E}@var{NN} | |
15617 | An error (such as memory fault) | |
15618 | @item @code{C}@var{CRC32} | |
15619 | A 32 bit cyclic redundancy check of the specified memory region. | |
15620 | @end table | |
15621 | ||
15622 | @item @code{q}@code{Offsets} --- query sect offs | |
c906108c | 15623 | |
8e04817f AC |
15624 | Get section offsets that the target used when re-locating the downloaded |
15625 | image. @emph{Note: while a @code{Bss} offset is included in the | |
15626 | response, @value{GDBN} ignores this and instead applies the @code{Data} | |
15627 | offset to the @code{Bss} section.} | |
c906108c | 15628 | |
ee2d5c50 AC |
15629 | Reply: |
15630 | @table @samp | |
15631 | @item @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz} | |
15632 | @end table | |
15633 | ||
15634 | @item @code{q}@code{P}@var{mode}@var{threadid} --- thread info request | |
15635 | ||
8e04817f AC |
15636 | Returns information on @var{threadid}. Where: @var{mode} is a hex |
15637 | encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID. | |
ee2d5c50 AC |
15638 | |
15639 | Reply: | |
15640 | @table @samp | |
15641 | @item * | |
15642 | @end table | |
15643 | ||
8e04817f | 15644 | See @code{remote.c:remote_unpack_thread_info_response()}. |
c906108c | 15645 | |
ee2d5c50 AC |
15646 | @item @code{q}@code{Rcmd,}@var{command} --- remote command |
15647 | ||
15648 | @var{command} (hex encoded) is passed to the local interpreter for | |
8e04817f AC |
15649 | execution. Invalid commands should be reported using the output string. |
15650 | Before the final result packet, the target may also respond with a | |
ee2d5c50 AC |
15651 | number of intermediate @code{O}@var{output} console output packets. |
15652 | @emph{Implementors should note that providing access to a stubs's | |
15653 | interpreter may have security implications}. | |
15654 | ||
15655 | Reply: | |
15656 | @table @samp | |
15657 | @item OK | |
8e04817f | 15658 | A command response with no output. |
ee2d5c50 | 15659 | @item @var{OUTPUT} |
8e04817f | 15660 | A command response with the hex encoded output string @var{OUTPUT}. |
ee2d5c50 | 15661 | @item @code{E}@var{NN} |
8e04817f | 15662 | Indicate a badly formed request. |
ee2d5c50 | 15663 | @item @samp{} |
8e04817f | 15664 | When @samp{q}@samp{Rcmd} is not recognized. |
ee2d5c50 AC |
15665 | @end table |
15666 | ||
15667 | @item @code{qSymbol::} --- symbol lookup | |
c906108c | 15668 | |
8e04817f AC |
15669 | Notify the target that @value{GDBN} is prepared to serve symbol lookup |
15670 | requests. Accept requests from the target for the values of symbols. | |
ee2d5c50 AC |
15671 | |
15672 | Reply: | |
15673 | @table @samp | |
15674 | @item @code{OK} | |
8e04817f | 15675 | The target does not need to look up any (more) symbols. |
ee2d5c50 AC |
15676 | @item @code{qSymbol:}@var{sym_name} |
15677 | The target requests the value of symbol @var{sym_name} (hex encoded). | |
15678 | @value{GDBN} may provide the value by using the | |
15679 | @code{qSymbol:}@var{sym_value}:@var{sym_name} message, described below. | |
15680 | @end table | |
15681 | ||
15682 | @item @code{qSymbol:}@var{sym_value}:@var{sym_name} --- symbol value | |
15683 | ||
15684 | Set the value of @var{sym_name} to @var{sym_value}. | |
15685 | ||
15686 | @var{sym_name} (hex encoded) is the name of a symbol whose value the | |
15687 | target has previously requested. | |
15688 | ||
15689 | @var{sym_value} (hex) is the value for symbol @var{sym_name}. If | |
15690 | @value{GDBN} cannot supply a value for @var{sym_name}, then this field | |
15691 | will be empty. | |
15692 | ||
15693 | Reply: | |
15694 | @table @samp | |
15695 | @item @code{OK} | |
8e04817f | 15696 | The target does not need to look up any (more) symbols. |
ee2d5c50 AC |
15697 | @item @code{qSymbol:}@var{sym_name} |
15698 | The target requests the value of a new symbol @var{sym_name} (hex | |
15699 | encoded). @value{GDBN} will continue to supply the values of symbols | |
15700 | (if available), until the target ceases to request them. | |
15701 | @end table | |
eb12ee30 | 15702 | |
ee2d5c50 AC |
15703 | @end table |
15704 | ||
15705 | @node Register Packet Format | |
15706 | @section Register Packet Format | |
eb12ee30 | 15707 | |
8e04817f | 15708 | The following @samp{g}/@samp{G} packets have previously been defined. |
ee2d5c50 AC |
15709 | In the below, some thirty-two bit registers are transferred as |
15710 | sixty-four bits. Those registers should be zero/sign extended (which?) | |
15711 | to fill the space allocated. Register bytes are transfered in target | |
15712 | byte order. The two nibbles within a register byte are transfered | |
15713 | most-significant - least-significant. | |
eb12ee30 | 15714 | |
ee2d5c50 | 15715 | @table @r |
eb12ee30 | 15716 | |
8e04817f | 15717 | @item MIPS32 |
ee2d5c50 | 15718 | |
8e04817f AC |
15719 | All registers are transfered as thirty-two bit quantities in the order: |
15720 | 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point | |
15721 | registers; fsr; fir; fp. | |
eb12ee30 | 15722 | |
8e04817f | 15723 | @item MIPS64 |
ee2d5c50 | 15724 | |
8e04817f AC |
15725 | All registers are transfered as sixty-four bit quantities (including |
15726 | thirty-two bit registers such as @code{sr}). The ordering is the same | |
15727 | as @code{MIPS32}. | |
eb12ee30 | 15728 | |
ee2d5c50 AC |
15729 | @end table |
15730 | ||
15731 | @node Examples | |
15732 | @section Examples | |
eb12ee30 | 15733 | |
8e04817f AC |
15734 | Example sequence of a target being re-started. Notice how the restart |
15735 | does not get any direct output: | |
eb12ee30 | 15736 | |
474c8240 | 15737 | @smallexample |
d2c6833e AC |
15738 | -> @code{R00} |
15739 | <- @code{+} | |
8e04817f | 15740 | @emph{target restarts} |
d2c6833e | 15741 | -> @code{?} |
8e04817f | 15742 | <- @code{+} |
d2c6833e AC |
15743 | <- @code{T001:1234123412341234} |
15744 | -> @code{+} | |
474c8240 | 15745 | @end smallexample |
eb12ee30 | 15746 | |
8e04817f | 15747 | Example sequence of a target being stepped by a single instruction: |
eb12ee30 | 15748 | |
474c8240 | 15749 | @smallexample |
d2c6833e | 15750 | -> @code{G1445@dots{}} |
8e04817f | 15751 | <- @code{+} |
d2c6833e AC |
15752 | -> @code{s} |
15753 | <- @code{+} | |
15754 | @emph{time passes} | |
15755 | <- @code{T001:1234123412341234} | |
8e04817f | 15756 | -> @code{+} |
d2c6833e | 15757 | -> @code{g} |
8e04817f | 15758 | <- @code{+} |
d2c6833e AC |
15759 | <- @code{1455@dots{}} |
15760 | -> @code{+} | |
474c8240 | 15761 | @end smallexample |
eb12ee30 | 15762 | |
aab4e0ec | 15763 | @include gpl.texi |
eb12ee30 | 15764 | |
6826cf00 EZ |
15765 | @include fdl.texi |
15766 | ||
6d2ebf8b | 15767 | @node Index |
c906108c SS |
15768 | @unnumbered Index |
15769 | ||
15770 | @printindex cp | |
15771 | ||
15772 | @tex | |
15773 | % I think something like @colophon should be in texinfo. In the | |
15774 | % meantime: | |
15775 | \long\def\colophon{\hbox to0pt{}\vfill | |
15776 | \centerline{The body of this manual is set in} | |
15777 | \centerline{\fontname\tenrm,} | |
15778 | \centerline{with headings in {\bf\fontname\tenbf}} | |
15779 | \centerline{and examples in {\tt\fontname\tentt}.} | |
15780 | \centerline{{\it\fontname\tenit\/},} | |
15781 | \centerline{{\bf\fontname\tenbf}, and} | |
15782 | \centerline{{\sl\fontname\tensl\/}} | |
15783 | \centerline{are used for emphasis.}\vfill} | |
15784 | \page\colophon | |
15785 | % Blame: doc@cygnus.com, 1991. | |
15786 | @end tex | |
15787 | ||
c906108c | 15788 | @bye |