| 1 | \input texinfo @c -*-texinfo-*- |
| 2 | @c Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, |
| 3 | @c 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 |
| 4 | @c Free Software Foundation, Inc. |
| 5 | @c |
| 6 | @c %**start of header |
| 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 |
| 13 | @settitle Debugging with @value{GDBN} |
| 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 | |
| 25 | @c readline appendices use @vindex, @findex and @ftable, |
| 26 | @c annotate.texi and gdbmi use @findex. |
| 27 | @syncodeindex vr cp |
| 28 | @syncodeindex fn cp |
| 29 | |
| 30 | @c !!set GDB manual's edition---not the same as GDB version! |
| 31 | @c This is updated by GNU Press. |
| 32 | @set EDITION Ninth |
| 33 | |
| 34 | @c !!set GDB edit command default editor |
| 35 | @set EDITOR /bin/ex |
| 36 | |
| 37 | @c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER. |
| 38 | |
| 39 | @c This is a dir.info fragment to support semi-automated addition of |
| 40 | @c manuals to an info tree. |
| 41 | @dircategory Software development |
| 42 | @direntry |
| 43 | * Gdb: (gdb). The GNU debugger. |
| 44 | @end direntry |
| 45 | |
| 46 | @copying |
| 47 | Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, |
| 48 | 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 |
| 49 | Free Software Foundation, Inc. |
| 50 | |
| 51 | Permission is granted to copy, distribute and/or modify this document |
| 52 | under the terms of the GNU Free Documentation License, Version 1.1 or |
| 53 | any later version published by the Free Software Foundation; with the |
| 54 | Invariant Sections being ``Free Software'' and ``Free Software Needs |
| 55 | Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' |
| 56 | and with the Back-Cover Texts as in (a) below. |
| 57 | |
| 58 | (a) The FSF's Back-Cover Text is: ``You are free to copy and modify |
| 59 | this GNU Manual. Buying copies from GNU Press supports the FSF in |
| 60 | developing GNU and promoting software freedom.'' |
| 61 | @end copying |
| 62 | |
| 63 | @ifnottex |
| 64 | This file documents the @sc{gnu} debugger @value{GDBN}. |
| 65 | |
| 66 | This is the @value{EDITION} Edition, of @cite{Debugging with |
| 67 | @value{GDBN}: the @sc{gnu} Source-Level Debugger} for @value{GDBN} |
| 68 | @ifset VERSION_PACKAGE |
| 69 | @value{VERSION_PACKAGE} |
| 70 | @end ifset |
| 71 | Version @value{GDBVN}. |
| 72 | |
| 73 | @insertcopying |
| 74 | @end ifnottex |
| 75 | |
| 76 | @titlepage |
| 77 | @title Debugging with @value{GDBN} |
| 78 | @subtitle The @sc{gnu} Source-Level Debugger |
| 79 | @sp 1 |
| 80 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
| 81 | @ifset VERSION_PACKAGE |
| 82 | @sp 1 |
| 83 | @subtitle @value{VERSION_PACKAGE} |
| 84 | @end ifset |
| 85 | @author Richard Stallman, Roland Pesch, Stan Shebs, et al. |
| 86 | @page |
| 87 | @tex |
| 88 | {\parskip=0pt |
| 89 | \hfill (Send bugs and comments on @value{GDBN} to @value{BUGURL}.)\par |
| 90 | \hfill {\it Debugging with @value{GDBN}}\par |
| 91 | \hfill \TeX{}info \texinfoversion\par |
| 92 | } |
| 93 | @end tex |
| 94 | |
| 95 | @vskip 0pt plus 1filll |
| 96 | Published by the Free Software Foundation @* |
| 97 | 51 Franklin Street, Fifth Floor, |
| 98 | Boston, MA 02110-1301, USA@* |
| 99 | ISBN 1-882114-77-9 @* |
| 100 | |
| 101 | @insertcopying |
| 102 | @page |
| 103 | This edition of the GDB manual is dedicated to the memory of Fred |
| 104 | Fish. Fred was a long-standing contributor to GDB and to Free |
| 105 | software in general. We will miss him. |
| 106 | @end titlepage |
| 107 | @page |
| 108 | |
| 109 | @ifnottex |
| 110 | @node Top, Summary, (dir), (dir) |
| 111 | |
| 112 | @top Debugging with @value{GDBN} |
| 113 | |
| 114 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. |
| 115 | |
| 116 | This is the @value{EDITION} Edition, for @value{GDBN} |
| 117 | @ifset VERSION_PACKAGE |
| 118 | @value{VERSION_PACKAGE} |
| 119 | @end ifset |
| 120 | Version @value{GDBVN}. |
| 121 | |
| 122 | Copyright (C) 1988-2009 Free Software Foundation, Inc. |
| 123 | |
| 124 | This edition of the GDB manual is dedicated to the memory of Fred |
| 125 | Fish. Fred was a long-standing contributor to GDB and to Free |
| 126 | software in general. We will miss him. |
| 127 | |
| 128 | @menu |
| 129 | * Summary:: Summary of @value{GDBN} |
| 130 | * Sample Session:: A sample @value{GDBN} session |
| 131 | |
| 132 | * Invocation:: Getting in and out of @value{GDBN} |
| 133 | * Commands:: @value{GDBN} commands |
| 134 | * Running:: Running programs under @value{GDBN} |
| 135 | * Stopping:: Stopping and continuing |
| 136 | * Reverse Execution:: Running programs backward |
| 137 | * Stack:: Examining the stack |
| 138 | * Source:: Examining source files |
| 139 | * Data:: Examining data |
| 140 | * Macros:: Preprocessor Macros |
| 141 | * Tracepoints:: Debugging remote targets non-intrusively |
| 142 | * Overlays:: Debugging programs that use overlays |
| 143 | |
| 144 | * Languages:: Using @value{GDBN} with different languages |
| 145 | |
| 146 | * Symbols:: Examining the symbol table |
| 147 | * Altering:: Altering execution |
| 148 | * GDB Files:: @value{GDBN} files |
| 149 | * Targets:: Specifying a debugging target |
| 150 | * Remote Debugging:: Debugging remote programs |
| 151 | * Configurations:: Configuration-specific information |
| 152 | * Controlling GDB:: Controlling @value{GDBN} |
| 153 | * Extending GDB:: Extending @value{GDBN} |
| 154 | * Interpreters:: Command Interpreters |
| 155 | * TUI:: @value{GDBN} Text User Interface |
| 156 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
| 157 | * GDB/MI:: @value{GDBN}'s Machine Interface. |
| 158 | * Annotations:: @value{GDBN}'s annotation interface. |
| 159 | |
| 160 | * GDB Bugs:: Reporting bugs in @value{GDBN} |
| 161 | |
| 162 | * Command Line Editing:: Command Line Editing |
| 163 | * Using History Interactively:: Using History Interactively |
| 164 | * Formatting Documentation:: How to format and print @value{GDBN} documentation |
| 165 | * Installing GDB:: Installing GDB |
| 166 | * Maintenance Commands:: Maintenance Commands |
| 167 | * Remote Protocol:: GDB Remote Serial Protocol |
| 168 | * Agent Expressions:: The GDB Agent Expression Mechanism |
| 169 | * Target Descriptions:: How targets can describe themselves to |
| 170 | @value{GDBN} |
| 171 | * Operating System Information:: Getting additional information from |
| 172 | the operating system |
| 173 | * Copying:: GNU General Public License says |
| 174 | how you can copy and share GDB |
| 175 | * GNU Free Documentation License:: The license for this documentation |
| 176 | * Index:: Index |
| 177 | @end menu |
| 178 | |
| 179 | @end ifnottex |
| 180 | |
| 181 | @contents |
| 182 | |
| 183 | @node Summary |
| 184 | @unnumbered Summary of @value{GDBN} |
| 185 | |
| 186 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is |
| 187 | going on ``inside'' another program while it executes---or what another |
| 188 | program was doing at the moment it crashed. |
| 189 | |
| 190 | @value{GDBN} can do four main kinds of things (plus other things in support of |
| 191 | these) to help you catch bugs in the act: |
| 192 | |
| 193 | @itemize @bullet |
| 194 | @item |
| 195 | Start your program, specifying anything that might affect its behavior. |
| 196 | |
| 197 | @item |
| 198 | Make your program stop on specified conditions. |
| 199 | |
| 200 | @item |
| 201 | Examine what has happened, when your program has stopped. |
| 202 | |
| 203 | @item |
| 204 | Change things in your program, so you can experiment with correcting the |
| 205 | effects of one bug and go on to learn about another. |
| 206 | @end itemize |
| 207 | |
| 208 | You can use @value{GDBN} to debug programs written in C and C@t{++}. |
| 209 | For more information, see @ref{Supported Languages,,Supported Languages}. |
| 210 | For more information, see @ref{C,,C and C++}. |
| 211 | |
| 212 | @cindex Modula-2 |
| 213 | Support for Modula-2 is partial. For information on Modula-2, see |
| 214 | @ref{Modula-2,,Modula-2}. |
| 215 | |
| 216 | @cindex Pascal |
| 217 | Debugging Pascal programs which use sets, subranges, file variables, or |
| 218 | nested functions does not currently work. @value{GDBN} does not support |
| 219 | entering expressions, printing values, or similar features using Pascal |
| 220 | syntax. |
| 221 | |
| 222 | @cindex Fortran |
| 223 | @value{GDBN} can be used to debug programs written in Fortran, although |
| 224 | it may be necessary to refer to some variables with a trailing |
| 225 | underscore. |
| 226 | |
| 227 | @value{GDBN} can be used to debug programs written in Objective-C, |
| 228 | using either the Apple/NeXT or the GNU Objective-C runtime. |
| 229 | |
| 230 | @menu |
| 231 | * Free Software:: Freely redistributable software |
| 232 | * Contributors:: Contributors to GDB |
| 233 | @end menu |
| 234 | |
| 235 | @node Free Software |
| 236 | @unnumberedsec Free Software |
| 237 | |
| 238 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} |
| 239 | General Public License |
| 240 | (GPL). The GPL gives you the freedom to copy or adapt a licensed |
| 241 | program---but every person getting a copy also gets with it the |
| 242 | freedom to modify that copy (which means that they must get access to |
| 243 | the source code), and the freedom to distribute further copies. |
| 244 | Typical software companies use copyrights to limit your freedoms; the |
| 245 | Free Software Foundation uses the GPL to preserve these freedoms. |
| 246 | |
| 247 | Fundamentally, the General Public License is a license which says that |
| 248 | you have these freedoms and that you cannot take these freedoms away |
| 249 | from anyone else. |
| 250 | |
| 251 | @unnumberedsec Free Software Needs Free Documentation |
| 252 | |
| 253 | The biggest deficiency in the free software community today is not in |
| 254 | the software---it is the lack of good free documentation that we can |
| 255 | include with the free software. Many of our most important |
| 256 | programs do not come with free reference manuals and free introductory |
| 257 | texts. Documentation is an essential part of any software package; |
| 258 | when an important free software package does not come with a free |
| 259 | manual and a free tutorial, that is a major gap. We have many such |
| 260 | gaps today. |
| 261 | |
| 262 | Consider Perl, for instance. The tutorial manuals that people |
| 263 | normally use are non-free. How did this come about? Because the |
| 264 | authors of those manuals published them with restrictive terms---no |
| 265 | copying, no modification, source files not available---which exclude |
| 266 | them from the free software world. |
| 267 | |
| 268 | That wasn't the first time this sort of thing happened, and it was far |
| 269 | from the last. Many times we have heard a GNU user eagerly describe a |
| 270 | manual that he is writing, his intended contribution to the community, |
| 271 | only to learn that he had ruined everything by signing a publication |
| 272 | contract to make it non-free. |
| 273 | |
| 274 | Free documentation, like free software, is a matter of freedom, not |
| 275 | price. The problem with the non-free manual is not that publishers |
| 276 | charge a price for printed copies---that in itself is fine. (The Free |
| 277 | Software Foundation sells printed copies of manuals, too.) The |
| 278 | problem is the restrictions on the use of the manual. Free manuals |
| 279 | are available in source code form, and give you permission to copy and |
| 280 | modify. Non-free manuals do not allow this. |
| 281 | |
| 282 | The criteria of freedom for a free manual are roughly the same as for |
| 283 | free software. Redistribution (including the normal kinds of |
| 284 | commercial redistribution) must be permitted, so that the manual can |
| 285 | accompany every copy of the program, both on-line and on paper. |
| 286 | |
| 287 | Permission for modification of the technical content is crucial too. |
| 288 | When people modify the software, adding or changing features, if they |
| 289 | are conscientious they will change the manual too---so they can |
| 290 | provide accurate and clear documentation for the modified program. A |
| 291 | manual that leaves you no choice but to write a new manual to document |
| 292 | a changed version of the program is not really available to our |
| 293 | community. |
| 294 | |
| 295 | Some kinds of limits on the way modification is handled are |
| 296 | acceptable. For example, requirements to preserve the original |
| 297 | author's copyright notice, the distribution terms, or the list of |
| 298 | authors, are ok. It is also no problem to require modified versions |
| 299 | to include notice that they were modified. Even entire sections that |
| 300 | may not be deleted or changed are acceptable, as long as they deal |
| 301 | with nontechnical topics (like this one). These kinds of restrictions |
| 302 | are acceptable because they don't obstruct the community's normal use |
| 303 | of the manual. |
| 304 | |
| 305 | However, it must be possible to modify all the @emph{technical} |
| 306 | content of the manual, and then distribute the result in all the usual |
| 307 | media, through all the usual channels. Otherwise, the restrictions |
| 308 | obstruct the use of the manual, it is not free, and we need another |
| 309 | manual to replace it. |
| 310 | |
| 311 | Please spread the word about this issue. Our community continues to |
| 312 | lose manuals to proprietary publishing. If we spread the word that |
| 313 | free software needs free reference manuals and free tutorials, perhaps |
| 314 | the next person who wants to contribute by writing documentation will |
| 315 | realize, before it is too late, that only free manuals contribute to |
| 316 | the free software community. |
| 317 | |
| 318 | If you are writing documentation, please insist on publishing it under |
| 319 | the GNU Free Documentation License or another free documentation |
| 320 | license. Remember that this decision requires your approval---you |
| 321 | don't have to let the publisher decide. Some commercial publishers |
| 322 | will use a free license if you insist, but they will not propose the |
| 323 | option; it is up to you to raise the issue and say firmly that this is |
| 324 | what you want. If the publisher you are dealing with refuses, please |
| 325 | try other publishers. If you're not sure whether a proposed license |
| 326 | is free, write to @email{licensing@@gnu.org}. |
| 327 | |
| 328 | You can encourage commercial publishers to sell more free, copylefted |
| 329 | manuals and tutorials by buying them, and particularly by buying |
| 330 | copies from the publishers that paid for their writing or for major |
| 331 | improvements. Meanwhile, try to avoid buying non-free documentation |
| 332 | at all. Check the distribution terms of a manual before you buy it, |
| 333 | and insist that whoever seeks your business must respect your freedom. |
| 334 | Check the history of the book, and try to reward the publishers that |
| 335 | have paid or pay the authors to work on it. |
| 336 | |
| 337 | The Free Software Foundation maintains a list of free documentation |
| 338 | published by other publishers, at |
| 339 | @url{http://www.fsf.org/doc/other-free-books.html}. |
| 340 | |
| 341 | @node Contributors |
| 342 | @unnumberedsec Contributors to @value{GDBN} |
| 343 | |
| 344 | Richard Stallman was the original author of @value{GDBN}, and of many |
| 345 | other @sc{gnu} programs. Many others have contributed to its |
| 346 | development. This section attempts to credit major contributors. One |
| 347 | of the virtues of free software is that everyone is free to contribute |
| 348 | to it; with regret, we cannot actually acknowledge everyone here. The |
| 349 | file @file{ChangeLog} in the @value{GDBN} distribution approximates a |
| 350 | blow-by-blow account. |
| 351 | |
| 352 | Changes much prior to version 2.0 are lost in the mists of time. |
| 353 | |
| 354 | @quotation |
| 355 | @emph{Plea:} Additions to this section are particularly welcome. If you |
| 356 | or your friends (or enemies, to be evenhanded) have been unfairly |
| 357 | omitted from this list, we would like to add your names! |
| 358 | @end quotation |
| 359 | |
| 360 | So that they may not regard their many labors as thankless, we |
| 361 | particularly thank those who shepherded @value{GDBN} through major |
| 362 | releases: |
| 363 | Andrew Cagney (releases 6.3, 6.2, 6.1, 6.0, 5.3, 5.2, 5.1 and 5.0); |
| 364 | Jim Blandy (release 4.18); |
| 365 | Jason Molenda (release 4.17); |
| 366 | Stan Shebs (release 4.14); |
| 367 | Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9); |
| 368 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4); |
| 369 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); |
| 370 | Jim Kingdon (releases 3.5, 3.4, and 3.3); |
| 371 | and Randy Smith (releases 3.2, 3.1, and 3.0). |
| 372 | |
| 373 | Richard Stallman, assisted at various times by Peter TerMaat, Chris |
| 374 | Hanson, and Richard Mlynarik, handled releases through 2.8. |
| 375 | |
| 376 | Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support |
| 377 | in @value{GDBN}, with significant additional contributions from Per |
| 378 | Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++} |
| 379 | demangler. Early work on C@t{++} was by Peter TerMaat (who also did |
| 380 | much general update work leading to release 3.0). |
| 381 | |
| 382 | @value{GDBN} uses the BFD subroutine library to examine multiple |
| 383 | object-file formats; BFD was a joint project of David V. |
| 384 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. |
| 385 | |
| 386 | David Johnson wrote the original COFF support; Pace Willison did |
| 387 | the original support for encapsulated COFF. |
| 388 | |
| 389 | Brent Benson of Harris Computer Systems contributed DWARF 2 support. |
| 390 | |
| 391 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. |
| 392 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS |
| 393 | support. |
| 394 | Jean-Daniel Fekete contributed Sun 386i support. |
| 395 | Chris Hanson improved the HP9000 support. |
| 396 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. |
| 397 | David Johnson contributed Encore Umax support. |
| 398 | Jyrki Kuoppala contributed Altos 3068 support. |
| 399 | Jeff Law contributed HP PA and SOM support. |
| 400 | Keith Packard contributed NS32K support. |
| 401 | Doug Rabson contributed Acorn Risc Machine support. |
| 402 | Bob Rusk contributed Harris Nighthawk CX-UX support. |
| 403 | Chris Smith contributed Convex support (and Fortran debugging). |
| 404 | Jonathan Stone contributed Pyramid support. |
| 405 | Michael Tiemann contributed SPARC support. |
| 406 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. |
| 407 | Pace Willison contributed Intel 386 support. |
| 408 | Jay Vosburgh contributed Symmetry support. |
| 409 | Marko Mlinar contributed OpenRISC 1000 support. |
| 410 | |
| 411 | Andreas Schwab contributed M68K @sc{gnu}/Linux support. |
| 412 | |
| 413 | Rich Schaefer and Peter Schauer helped with support of SunOS shared |
| 414 | libraries. |
| 415 | |
| 416 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree |
| 417 | about several machine instruction sets. |
| 418 | |
| 419 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop |
| 420 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM |
| 421 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, |
| 422 | and RDI targets, respectively. |
| 423 | |
| 424 | Brian Fox is the author of the readline libraries providing |
| 425 | command-line editing and command history. |
| 426 | |
| 427 | Andrew Beers of SUNY Buffalo wrote the language-switching code, the |
| 428 | Modula-2 support, and contributed the Languages chapter of this manual. |
| 429 | |
| 430 | Fred Fish wrote most of the support for Unix System Vr4. |
| 431 | He also enhanced the command-completion support to cover C@t{++} overloaded |
| 432 | symbols. |
| 433 | |
| 434 | Hitachi America (now Renesas America), Ltd. sponsored the support for |
| 435 | H8/300, H8/500, and Super-H processors. |
| 436 | |
| 437 | NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors. |
| 438 | |
| 439 | Mitsubishi (now Renesas) sponsored the support for D10V, D30V, and M32R/D |
| 440 | processors. |
| 441 | |
| 442 | Toshiba sponsored the support for the TX39 Mips processor. |
| 443 | |
| 444 | Matsushita sponsored the support for the MN10200 and MN10300 processors. |
| 445 | |
| 446 | Fujitsu sponsored the support for SPARClite and FR30 processors. |
| 447 | |
| 448 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware |
| 449 | watchpoints. |
| 450 | |
| 451 | Michael Snyder added support for tracepoints. |
| 452 | |
| 453 | Stu Grossman wrote gdbserver. |
| 454 | |
| 455 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made |
| 456 | nearly innumerable bug fixes and cleanups throughout @value{GDBN}. |
| 457 | |
| 458 | The following people at the Hewlett-Packard Company contributed |
| 459 | support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0 |
| 460 | (narrow mode), HP's implementation of kernel threads, HP's aC@t{++} |
| 461 | compiler, and the Text User Interface (nee Terminal User Interface): |
| 462 | Ben Krepp, Richard Title, John Bishop, Susan Macchia, Kathy Mann, |
| 463 | Satish Pai, India Paul, Steve Rehrauer, and Elena Zannoni. Kim Haase |
| 464 | provided HP-specific information in this manual. |
| 465 | |
| 466 | DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project. |
| 467 | Robert Hoehne made significant contributions to the DJGPP port. |
| 468 | |
| 469 | Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its |
| 470 | development since 1991. Cygnus engineers who have worked on @value{GDBN} |
| 471 | fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin |
| 472 | Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim |
| 473 | Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler, |
| 474 | Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek |
| 475 | Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In |
| 476 | addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton, |
| 477 | JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug |
| 478 | Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff |
| 479 | Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner, |
| 480 | Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin |
| 481 | Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela |
| 482 | Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David |
| 483 | Zuhn have made contributions both large and small. |
| 484 | |
| 485 | Andrew Cagney, Fernando Nasser, and Elena Zannoni, while working for |
| 486 | Cygnus Solutions, implemented the original @sc{gdb/mi} interface. |
| 487 | |
| 488 | Jim Blandy added support for preprocessor macros, while working for Red |
| 489 | Hat. |
| 490 | |
| 491 | Andrew Cagney designed @value{GDBN}'s architecture vector. Many |
| 492 | people including Andrew Cagney, Stephane Carrez, Randolph Chung, Nick |
| 493 | Duffek, Richard Henderson, Mark Kettenis, Grace Sainsbury, Kei |
| 494 | Sakamoto, Yoshinori Sato, Michael Snyder, Andreas Schwab, Jason |
| 495 | Thorpe, Corinna Vinschen, Ulrich Weigand, and Elena Zannoni, helped |
| 496 | with the migration of old architectures to this new framework. |
| 497 | |
| 498 | Andrew Cagney completely re-designed and re-implemented @value{GDBN}'s |
| 499 | unwinder framework, this consisting of a fresh new design featuring |
| 500 | frame IDs, independent frame sniffers, and the sentinel frame. Mark |
| 501 | Kettenis implemented the @sc{dwarf 2} unwinder, Jeff Johnston the |
| 502 | libunwind unwinder, and Andrew Cagney the dummy, sentinel, tramp, and |
| 503 | trad unwinders. The architecture-specific changes, each involving a |
| 504 | complete rewrite of the architecture's frame code, were carried out by |
| 505 | Jim Blandy, Joel Brobecker, Kevin Buettner, Andrew Cagney, Stephane |
| 506 | Carrez, Randolph Chung, Orjan Friberg, Richard Henderson, Daniel |
| 507 | Jacobowitz, Jeff Johnston, Mark Kettenis, Theodore A. Roth, Kei |
| 508 | Sakamoto, Yoshinori Sato, Michael Snyder, Corinna Vinschen, and Ulrich |
| 509 | Weigand. |
| 510 | |
| 511 | Christian Zankel, Ross Morley, Bob Wilson, and Maxim Grigoriev from |
| 512 | Tensilica, Inc.@: contributed support for Xtensa processors. Others |
| 513 | who have worked on the Xtensa port of @value{GDBN} in the past include |
| 514 | Steve Tjiang, John Newlin, and Scott Foehner. |
| 515 | |
| 516 | @node Sample Session |
| 517 | @chapter A Sample @value{GDBN} Session |
| 518 | |
| 519 | You can use this manual at your leisure to read all about @value{GDBN}. |
| 520 | However, a handful of commands are enough to get started using the |
| 521 | debugger. This chapter illustrates those commands. |
| 522 | |
| 523 | @iftex |
| 524 | In this sample session, we emphasize user input like this: @b{input}, |
| 525 | to make it easier to pick out from the surrounding output. |
| 526 | @end iftex |
| 527 | |
| 528 | @c FIXME: this example may not be appropriate for some configs, where |
| 529 | @c FIXME...primary interest is in remote use. |
| 530 | |
| 531 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro |
| 532 | processor) exhibits the following bug: sometimes, when we change its |
| 533 | quote strings from the default, the commands used to capture one macro |
| 534 | definition within another stop working. In the following short @code{m4} |
| 535 | session, we define a macro @code{foo} which expands to @code{0000}; we |
| 536 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the |
| 537 | same thing. However, when we change the open quote string to |
| 538 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same |
| 539 | procedure fails to define a new synonym @code{baz}: |
| 540 | |
| 541 | @smallexample |
| 542 | $ @b{cd gnu/m4} |
| 543 | $ @b{./m4} |
| 544 | @b{define(foo,0000)} |
| 545 | |
| 546 | @b{foo} |
| 547 | 0000 |
| 548 | @b{define(bar,defn(`foo'))} |
| 549 | |
| 550 | @b{bar} |
| 551 | 0000 |
| 552 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
| 553 | |
| 554 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
| 555 | @b{baz} |
| 556 | @b{Ctrl-d} |
| 557 | m4: End of input: 0: fatal error: EOF in string |
| 558 | @end smallexample |
| 559 | |
| 560 | @noindent |
| 561 | Let us use @value{GDBN} to try to see what is going on. |
| 562 | |
| 563 | @smallexample |
| 564 | $ @b{@value{GDBP} m4} |
| 565 | @c FIXME: this falsifies the exact text played out, to permit smallbook |
| 566 | @c FIXME... format to come out better. |
| 567 | @value{GDBN} is free software and you are welcome to distribute copies |
| 568 | of it under certain conditions; type "show copying" to see |
| 569 | the conditions. |
| 570 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
| 571 | for details. |
| 572 | |
| 573 | @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc... |
| 574 | (@value{GDBP}) |
| 575 | @end smallexample |
| 576 | |
| 577 | @noindent |
| 578 | @value{GDBN} reads only enough symbol data to know where to find the |
| 579 | rest when needed; as a result, the first prompt comes up very quickly. |
| 580 | We now tell @value{GDBN} to use a narrower display width than usual, so |
| 581 | that examples fit in this manual. |
| 582 | |
| 583 | @smallexample |
| 584 | (@value{GDBP}) @b{set width 70} |
| 585 | @end smallexample |
| 586 | |
| 587 | @noindent |
| 588 | We need to see how the @code{m4} built-in @code{changequote} works. |
| 589 | Having looked at the source, we know the relevant subroutine is |
| 590 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} |
| 591 | @code{break} command. |
| 592 | |
| 593 | @smallexample |
| 594 | (@value{GDBP}) @b{break m4_changequote} |
| 595 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. |
| 596 | @end smallexample |
| 597 | |
| 598 | @noindent |
| 599 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} |
| 600 | control; as long as control does not reach the @code{m4_changequote} |
| 601 | subroutine, the program runs as usual: |
| 602 | |
| 603 | @smallexample |
| 604 | (@value{GDBP}) @b{run} |
| 605 | Starting program: /work/Editorial/gdb/gnu/m4/m4 |
| 606 | @b{define(foo,0000)} |
| 607 | |
| 608 | @b{foo} |
| 609 | 0000 |
| 610 | @end smallexample |
| 611 | |
| 612 | @noindent |
| 613 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} |
| 614 | suspends execution of @code{m4}, displaying information about the |
| 615 | context where it stops. |
| 616 | |
| 617 | @smallexample |
| 618 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
| 619 | |
| 620 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) |
| 621 | at builtin.c:879 |
| 622 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) |
| 623 | @end smallexample |
| 624 | |
| 625 | @noindent |
| 626 | Now we use the command @code{n} (@code{next}) to advance execution to |
| 627 | the next line of the current function. |
| 628 | |
| 629 | @smallexample |
| 630 | (@value{GDBP}) @b{n} |
| 631 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ |
| 632 | : nil, |
| 633 | @end smallexample |
| 634 | |
| 635 | @noindent |
| 636 | @code{set_quotes} looks like a promising subroutine. We can go into it |
| 637 | by using the command @code{s} (@code{step}) instead of @code{next}. |
| 638 | @code{step} goes to the next line to be executed in @emph{any} |
| 639 | subroutine, so it steps into @code{set_quotes}. |
| 640 | |
| 641 | @smallexample |
| 642 | (@value{GDBP}) @b{s} |
| 643 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
| 644 | at input.c:530 |
| 645 | 530 if (lquote != def_lquote) |
| 646 | @end smallexample |
| 647 | |
| 648 | @noindent |
| 649 | The display that shows the subroutine where @code{m4} is now |
| 650 | suspended (and its arguments) is called a stack frame display. It |
| 651 | shows a summary of the stack. We can use the @code{backtrace} |
| 652 | command (which can also be spelled @code{bt}), to see where we are |
| 653 | in the stack as a whole: the @code{backtrace} command displays a |
| 654 | stack frame for each active subroutine. |
| 655 | |
| 656 | @smallexample |
| 657 | (@value{GDBP}) @b{bt} |
| 658 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
| 659 | at input.c:530 |
| 660 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) |
| 661 | at builtin.c:882 |
| 662 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 |
| 663 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) |
| 664 | at macro.c:71 |
| 665 | #4 0x79dc in expand_input () at macro.c:40 |
| 666 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 |
| 667 | @end smallexample |
| 668 | |
| 669 | @noindent |
| 670 | We step through a few more lines to see what happens. The first two |
| 671 | times, we can use @samp{s}; the next two times we use @code{n} to avoid |
| 672 | falling into the @code{xstrdup} subroutine. |
| 673 | |
| 674 | @smallexample |
| 675 | (@value{GDBP}) @b{s} |
| 676 | 0x3b5c 532 if (rquote != def_rquote) |
| 677 | (@value{GDBP}) @b{s} |
| 678 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ |
| 679 | def_lquote : xstrdup(lq); |
| 680 | (@value{GDBP}) @b{n} |
| 681 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ |
| 682 | : xstrdup(rq); |
| 683 | (@value{GDBP}) @b{n} |
| 684 | 538 len_lquote = strlen(rquote); |
| 685 | @end smallexample |
| 686 | |
| 687 | @noindent |
| 688 | The last line displayed looks a little odd; we can examine the variables |
| 689 | @code{lquote} and @code{rquote} to see if they are in fact the new left |
| 690 | and right quotes we specified. We use the command @code{p} |
| 691 | (@code{print}) to see their values. |
| 692 | |
| 693 | @smallexample |
| 694 | (@value{GDBP}) @b{p lquote} |
| 695 | $1 = 0x35d40 "<QUOTE>" |
| 696 | (@value{GDBP}) @b{p rquote} |
| 697 | $2 = 0x35d50 "<UNQUOTE>" |
| 698 | @end smallexample |
| 699 | |
| 700 | @noindent |
| 701 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. |
| 702 | To look at some context, we can display ten lines of source |
| 703 | surrounding the current line with the @code{l} (@code{list}) command. |
| 704 | |
| 705 | @smallexample |
| 706 | (@value{GDBP}) @b{l} |
| 707 | 533 xfree(rquote); |
| 708 | 534 |
| 709 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ |
| 710 | : xstrdup (lq); |
| 711 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ |
| 712 | : xstrdup (rq); |
| 713 | 537 |
| 714 | 538 len_lquote = strlen(rquote); |
| 715 | 539 len_rquote = strlen(lquote); |
| 716 | 540 @} |
| 717 | 541 |
| 718 | 542 void |
| 719 | @end smallexample |
| 720 | |
| 721 | @noindent |
| 722 | Let us step past the two lines that set @code{len_lquote} and |
| 723 | @code{len_rquote}, and then examine the values of those variables. |
| 724 | |
| 725 | @smallexample |
| 726 | (@value{GDBP}) @b{n} |
| 727 | 539 len_rquote = strlen(lquote); |
| 728 | (@value{GDBP}) @b{n} |
| 729 | 540 @} |
| 730 | (@value{GDBP}) @b{p len_lquote} |
| 731 | $3 = 9 |
| 732 | (@value{GDBP}) @b{p len_rquote} |
| 733 | $4 = 7 |
| 734 | @end smallexample |
| 735 | |
| 736 | @noindent |
| 737 | That certainly looks wrong, assuming @code{len_lquote} and |
| 738 | @code{len_rquote} are meant to be the lengths of @code{lquote} and |
| 739 | @code{rquote} respectively. We can set them to better values using |
| 740 | the @code{p} command, since it can print the value of |
| 741 | any expression---and that expression can include subroutine calls and |
| 742 | assignments. |
| 743 | |
| 744 | @smallexample |
| 745 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} |
| 746 | $5 = 7 |
| 747 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} |
| 748 | $6 = 9 |
| 749 | @end smallexample |
| 750 | |
| 751 | @noindent |
| 752 | Is that enough to fix the problem of using the new quotes with the |
| 753 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue |
| 754 | executing with the @code{c} (@code{continue}) command, and then try the |
| 755 | example that caused trouble initially: |
| 756 | |
| 757 | @smallexample |
| 758 | (@value{GDBP}) @b{c} |
| 759 | Continuing. |
| 760 | |
| 761 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
| 762 | |
| 763 | baz |
| 764 | 0000 |
| 765 | @end smallexample |
| 766 | |
| 767 | @noindent |
| 768 | Success! The new quotes now work just as well as the default ones. The |
| 769 | problem seems to have been just the two typos defining the wrong |
| 770 | lengths. We allow @code{m4} exit by giving it an EOF as input: |
| 771 | |
| 772 | @smallexample |
| 773 | @b{Ctrl-d} |
| 774 | Program exited normally. |
| 775 | @end smallexample |
| 776 | |
| 777 | @noindent |
| 778 | The message @samp{Program exited normally.} is from @value{GDBN}; it |
| 779 | indicates @code{m4} has finished executing. We can end our @value{GDBN} |
| 780 | session with the @value{GDBN} @code{quit} command. |
| 781 | |
| 782 | @smallexample |
| 783 | (@value{GDBP}) @b{quit} |
| 784 | @end smallexample |
| 785 | |
| 786 | @node Invocation |
| 787 | @chapter Getting In and Out of @value{GDBN} |
| 788 | |
| 789 | This chapter discusses how to start @value{GDBN}, and how to get out of it. |
| 790 | The essentials are: |
| 791 | @itemize @bullet |
| 792 | @item |
| 793 | type @samp{@value{GDBP}} to start @value{GDBN}. |
| 794 | @item |
| 795 | type @kbd{quit} or @kbd{Ctrl-d} to exit. |
| 796 | @end itemize |
| 797 | |
| 798 | @menu |
| 799 | * Invoking GDB:: How to start @value{GDBN} |
| 800 | * Quitting GDB:: How to quit @value{GDBN} |
| 801 | * Shell Commands:: How to use shell commands inside @value{GDBN} |
| 802 | * Logging Output:: How to log @value{GDBN}'s output to a file |
| 803 | @end menu |
| 804 | |
| 805 | @node Invoking GDB |
| 806 | @section Invoking @value{GDBN} |
| 807 | |
| 808 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
| 809 | @value{GDBN} reads commands from the terminal until you tell it to exit. |
| 810 | |
| 811 | You can also run @code{@value{GDBP}} with a variety of arguments and options, |
| 812 | to specify more of your debugging environment at the outset. |
| 813 | |
| 814 | The command-line options described here are designed |
| 815 | to cover a variety of situations; in some environments, some of these |
| 816 | options may effectively be unavailable. |
| 817 | |
| 818 | The most usual way to start @value{GDBN} is with one argument, |
| 819 | specifying an executable program: |
| 820 | |
| 821 | @smallexample |
| 822 | @value{GDBP} @var{program} |
| 823 | @end smallexample |
| 824 | |
| 825 | @noindent |
| 826 | You can also start with both an executable program and a core file |
| 827 | specified: |
| 828 | |
| 829 | @smallexample |
| 830 | @value{GDBP} @var{program} @var{core} |
| 831 | @end smallexample |
| 832 | |
| 833 | You can, instead, specify a process ID as a second argument, if you want |
| 834 | to debug a running process: |
| 835 | |
| 836 | @smallexample |
| 837 | @value{GDBP} @var{program} 1234 |
| 838 | @end smallexample |
| 839 | |
| 840 | @noindent |
| 841 | would attach @value{GDBN} to process @code{1234} (unless you also have a file |
| 842 | named @file{1234}; @value{GDBN} does check for a core file first). |
| 843 | |
| 844 | Taking advantage of the second command-line argument requires a fairly |
| 845 | complete operating system; when you use @value{GDBN} as a remote |
| 846 | debugger attached to a bare board, there may not be any notion of |
| 847 | ``process'', and there is often no way to get a core dump. @value{GDBN} |
| 848 | will warn you if it is unable to attach or to read core dumps. |
| 849 | |
| 850 | You can optionally have @code{@value{GDBP}} pass any arguments after the |
| 851 | executable file to the inferior using @code{--args}. This option stops |
| 852 | option processing. |
| 853 | @smallexample |
| 854 | @value{GDBP} --args gcc -O2 -c foo.c |
| 855 | @end smallexample |
| 856 | This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set |
| 857 | @code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}. |
| 858 | |
| 859 | You can run @code{@value{GDBP}} without printing the front material, which describes |
| 860 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: |
| 861 | |
| 862 | @smallexample |
| 863 | @value{GDBP} -silent |
| 864 | @end smallexample |
| 865 | |
| 866 | @noindent |
| 867 | You can further control how @value{GDBN} starts up by using command-line |
| 868 | options. @value{GDBN} itself can remind you of the options available. |
| 869 | |
| 870 | @noindent |
| 871 | Type |
| 872 | |
| 873 | @smallexample |
| 874 | @value{GDBP} -help |
| 875 | @end smallexample |
| 876 | |
| 877 | @noindent |
| 878 | to display all available options and briefly describe their use |
| 879 | (@samp{@value{GDBP} -h} is a shorter equivalent). |
| 880 | |
| 881 | All options and command line arguments you give are processed |
| 882 | in sequential order. The order makes a difference when the |
| 883 | @samp{-x} option is used. |
| 884 | |
| 885 | |
| 886 | @menu |
| 887 | * File Options:: Choosing files |
| 888 | * Mode Options:: Choosing modes |
| 889 | * Startup:: What @value{GDBN} does during startup |
| 890 | @end menu |
| 891 | |
| 892 | @node File Options |
| 893 | @subsection Choosing Files |
| 894 | |
| 895 | When @value{GDBN} starts, it reads any arguments other than options as |
| 896 | specifying an executable file and core file (or process ID). This is |
| 897 | the same as if the arguments were specified by the @samp{-se} and |
| 898 | @samp{-c} (or @samp{-p}) options respectively. (@value{GDBN} reads the |
| 899 | first argument that does not have an associated option flag as |
| 900 | equivalent to the @samp{-se} option followed by that argument; and the |
| 901 | second argument that does not have an associated option flag, if any, as |
| 902 | equivalent to the @samp{-c}/@samp{-p} option followed by that argument.) |
| 903 | If the second argument begins with a decimal digit, @value{GDBN} will |
| 904 | first attempt to attach to it as a process, and if that fails, attempt |
| 905 | to open it as a corefile. If you have a corefile whose name begins with |
| 906 | a digit, you can prevent @value{GDBN} from treating it as a pid by |
| 907 | prefixing it with @file{./}, e.g.@: @file{./12345}. |
| 908 | |
| 909 | If @value{GDBN} has not been configured to included core file support, |
| 910 | such as for most embedded targets, then it will complain about a second |
| 911 | argument and ignore it. |
| 912 | |
| 913 | Many options have both long and short forms; both are shown in the |
| 914 | following list. @value{GDBN} also recognizes the long forms if you truncate |
| 915 | them, so long as enough of the option is present to be unambiguous. |
| 916 | (If you prefer, you can flag option arguments with @samp{--} rather |
| 917 | than @samp{-}, though we illustrate the more usual convention.) |
| 918 | |
| 919 | @c NOTE: the @cindex entries here use double dashes ON PURPOSE. This |
| 920 | @c way, both those who look for -foo and --foo in the index, will find |
| 921 | @c it. |
| 922 | |
| 923 | @table @code |
| 924 | @item -symbols @var{file} |
| 925 | @itemx -s @var{file} |
| 926 | @cindex @code{--symbols} |
| 927 | @cindex @code{-s} |
| 928 | Read symbol table from file @var{file}. |
| 929 | |
| 930 | @item -exec @var{file} |
| 931 | @itemx -e @var{file} |
| 932 | @cindex @code{--exec} |
| 933 | @cindex @code{-e} |
| 934 | Use file @var{file} as the executable file to execute when appropriate, |
| 935 | and for examining pure data in conjunction with a core dump. |
| 936 | |
| 937 | @item -se @var{file} |
| 938 | @cindex @code{--se} |
| 939 | Read symbol table from file @var{file} and use it as the executable |
| 940 | file. |
| 941 | |
| 942 | @item -core @var{file} |
| 943 | @itemx -c @var{file} |
| 944 | @cindex @code{--core} |
| 945 | @cindex @code{-c} |
| 946 | Use file @var{file} as a core dump to examine. |
| 947 | |
| 948 | @item -pid @var{number} |
| 949 | @itemx -p @var{number} |
| 950 | @cindex @code{--pid} |
| 951 | @cindex @code{-p} |
| 952 | Connect to process ID @var{number}, as with the @code{attach} command. |
| 953 | |
| 954 | @item -command @var{file} |
| 955 | @itemx -x @var{file} |
| 956 | @cindex @code{--command} |
| 957 | @cindex @code{-x} |
| 958 | Execute @value{GDBN} commands from file @var{file}. @xref{Command |
| 959 | Files,, Command files}. |
| 960 | |
| 961 | @item -eval-command @var{command} |
| 962 | @itemx -ex @var{command} |
| 963 | @cindex @code{--eval-command} |
| 964 | @cindex @code{-ex} |
| 965 | Execute a single @value{GDBN} command. |
| 966 | |
| 967 | This option may be used multiple times to call multiple commands. It may |
| 968 | also be interleaved with @samp{-command} as required. |
| 969 | |
| 970 | @smallexample |
| 971 | @value{GDBP} -ex 'target sim' -ex 'load' \ |
| 972 | -x setbreakpoints -ex 'run' a.out |
| 973 | @end smallexample |
| 974 | |
| 975 | @item -directory @var{directory} |
| 976 | @itemx -d @var{directory} |
| 977 | @cindex @code{--directory} |
| 978 | @cindex @code{-d} |
| 979 | Add @var{directory} to the path to search for source and script files. |
| 980 | |
| 981 | @item -r |
| 982 | @itemx -readnow |
| 983 | @cindex @code{--readnow} |
| 984 | @cindex @code{-r} |
| 985 | Read each symbol file's entire symbol table immediately, rather than |
| 986 | the default, which is to read it incrementally as it is needed. |
| 987 | This makes startup slower, but makes future operations faster. |
| 988 | |
| 989 | @end table |
| 990 | |
| 991 | @node Mode Options |
| 992 | @subsection Choosing Modes |
| 993 | |
| 994 | You can run @value{GDBN} in various alternative modes---for example, in |
| 995 | batch mode or quiet mode. |
| 996 | |
| 997 | @table @code |
| 998 | @item -nx |
| 999 | @itemx -n |
| 1000 | @cindex @code{--nx} |
| 1001 | @cindex @code{-n} |
| 1002 | Do not execute commands found in any initialization files. Normally, |
| 1003 | @value{GDBN} executes the commands in these files after all the command |
| 1004 | options and arguments have been processed. @xref{Command Files,,Command |
| 1005 | Files}. |
| 1006 | |
| 1007 | @item -quiet |
| 1008 | @itemx -silent |
| 1009 | @itemx -q |
| 1010 | @cindex @code{--quiet} |
| 1011 | @cindex @code{--silent} |
| 1012 | @cindex @code{-q} |
| 1013 | ``Quiet''. Do not print the introductory and copyright messages. These |
| 1014 | messages are also suppressed in batch mode. |
| 1015 | |
| 1016 | @item -batch |
| 1017 | @cindex @code{--batch} |
| 1018 | Run in batch mode. Exit with status @code{0} after processing all the |
| 1019 | command files specified with @samp{-x} (and all commands from |
| 1020 | initialization files, if not inhibited with @samp{-n}). Exit with |
| 1021 | nonzero status if an error occurs in executing the @value{GDBN} commands |
| 1022 | in the command files. |
| 1023 | |
| 1024 | Batch mode may be useful for running @value{GDBN} as a filter, for |
| 1025 | example to download and run a program on another computer; in order to |
| 1026 | make this more useful, the message |
| 1027 | |
| 1028 | @smallexample |
| 1029 | Program exited normally. |
| 1030 | @end smallexample |
| 1031 | |
| 1032 | @noindent |
| 1033 | (which is ordinarily issued whenever a program running under |
| 1034 | @value{GDBN} control terminates) is not issued when running in batch |
| 1035 | mode. |
| 1036 | |
| 1037 | @item -batch-silent |
| 1038 | @cindex @code{--batch-silent} |
| 1039 | Run in batch mode exactly like @samp{-batch}, but totally silently. All |
| 1040 | @value{GDBN} output to @code{stdout} is prevented (@code{stderr} is |
| 1041 | unaffected). This is much quieter than @samp{-silent} and would be useless |
| 1042 | for an interactive session. |
| 1043 | |
| 1044 | This is particularly useful when using targets that give @samp{Loading section} |
| 1045 | messages, for example. |
| 1046 | |
| 1047 | Note that targets that give their output via @value{GDBN}, as opposed to |
| 1048 | writing directly to @code{stdout}, will also be made silent. |
| 1049 | |
| 1050 | @item -return-child-result |
| 1051 | @cindex @code{--return-child-result} |
| 1052 | The return code from @value{GDBN} will be the return code from the child |
| 1053 | process (the process being debugged), with the following exceptions: |
| 1054 | |
| 1055 | @itemize @bullet |
| 1056 | @item |
| 1057 | @value{GDBN} exits abnormally. E.g., due to an incorrect argument or an |
| 1058 | internal error. In this case the exit code is the same as it would have been |
| 1059 | without @samp{-return-child-result}. |
| 1060 | @item |
| 1061 | The user quits with an explicit value. E.g., @samp{quit 1}. |
| 1062 | @item |
| 1063 | The child process never runs, or is not allowed to terminate, in which case |
| 1064 | the exit code will be -1. |
| 1065 | @end itemize |
| 1066 | |
| 1067 | This option is useful in conjunction with @samp{-batch} or @samp{-batch-silent}, |
| 1068 | when @value{GDBN} is being used as a remote program loader or simulator |
| 1069 | interface. |
| 1070 | |
| 1071 | @item -nowindows |
| 1072 | @itemx -nw |
| 1073 | @cindex @code{--nowindows} |
| 1074 | @cindex @code{-nw} |
| 1075 | ``No windows''. If @value{GDBN} comes with a graphical user interface |
| 1076 | (GUI) built in, then this option tells @value{GDBN} to only use the command-line |
| 1077 | interface. If no GUI is available, this option has no effect. |
| 1078 | |
| 1079 | @item -windows |
| 1080 | @itemx -w |
| 1081 | @cindex @code{--windows} |
| 1082 | @cindex @code{-w} |
| 1083 | If @value{GDBN} includes a GUI, then this option requires it to be |
| 1084 | used if possible. |
| 1085 | |
| 1086 | @item -cd @var{directory} |
| 1087 | @cindex @code{--cd} |
| 1088 | Run @value{GDBN} using @var{directory} as its working directory, |
| 1089 | instead of the current directory. |
| 1090 | |
| 1091 | @item -fullname |
| 1092 | @itemx -f |
| 1093 | @cindex @code{--fullname} |
| 1094 | @cindex @code{-f} |
| 1095 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a |
| 1096 | subprocess. It tells @value{GDBN} to output the full file name and line |
| 1097 | number in a standard, recognizable fashion each time a stack frame is |
| 1098 | displayed (which includes each time your program stops). This |
| 1099 | recognizable format looks like two @samp{\032} characters, followed by |
| 1100 | the file name, line number and character position separated by colons, |
| 1101 | and a newline. The Emacs-to-@value{GDBN} interface program uses the two |
| 1102 | @samp{\032} characters as a signal to display the source code for the |
| 1103 | frame. |
| 1104 | |
| 1105 | @item -epoch |
| 1106 | @cindex @code{--epoch} |
| 1107 | The Epoch Emacs-@value{GDBN} interface sets this option when it runs |
| 1108 | @value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print |
| 1109 | routines so as to allow Epoch to display values of expressions in a |
| 1110 | separate window. |
| 1111 | |
| 1112 | @item -annotate @var{level} |
| 1113 | @cindex @code{--annotate} |
| 1114 | This option sets the @dfn{annotation level} inside @value{GDBN}. Its |
| 1115 | effect is identical to using @samp{set annotate @var{level}} |
| 1116 | (@pxref{Annotations}). The annotation @var{level} controls how much |
| 1117 | information @value{GDBN} prints together with its prompt, values of |
| 1118 | expressions, source lines, and other types of output. Level 0 is the |
| 1119 | normal, level 1 is for use when @value{GDBN} is run as a subprocess of |
| 1120 | @sc{gnu} Emacs, level 3 is the maximum annotation suitable for programs |
| 1121 | that control @value{GDBN}, and level 2 has been deprecated. |
| 1122 | |
| 1123 | The annotation mechanism has largely been superseded by @sc{gdb/mi} |
| 1124 | (@pxref{GDB/MI}). |
| 1125 | |
| 1126 | @item --args |
| 1127 | @cindex @code{--args} |
| 1128 | Change interpretation of command line so that arguments following the |
| 1129 | executable file are passed as command line arguments to the inferior. |
| 1130 | This option stops option processing. |
| 1131 | |
| 1132 | @item -baud @var{bps} |
| 1133 | @itemx -b @var{bps} |
| 1134 | @cindex @code{--baud} |
| 1135 | @cindex @code{-b} |
| 1136 | Set the line speed (baud rate or bits per second) of any serial |
| 1137 | interface used by @value{GDBN} for remote debugging. |
| 1138 | |
| 1139 | @item -l @var{timeout} |
| 1140 | @cindex @code{-l} |
| 1141 | Set the timeout (in seconds) of any communication used by @value{GDBN} |
| 1142 | for remote debugging. |
| 1143 | |
| 1144 | @item -tty @var{device} |
| 1145 | @itemx -t @var{device} |
| 1146 | @cindex @code{--tty} |
| 1147 | @cindex @code{-t} |
| 1148 | Run using @var{device} for your program's standard input and output. |
| 1149 | @c FIXME: kingdon thinks there is more to -tty. Investigate. |
| 1150 | |
| 1151 | @c resolve the situation of these eventually |
| 1152 | @item -tui |
| 1153 | @cindex @code{--tui} |
| 1154 | Activate the @dfn{Text User Interface} when starting. The Text User |
| 1155 | Interface manages several text windows on the terminal, showing |
| 1156 | source, assembly, registers and @value{GDBN} command outputs |
| 1157 | (@pxref{TUI, ,@value{GDBN} Text User Interface}). Alternatively, the |
| 1158 | Text User Interface can be enabled by invoking the program |
| 1159 | @samp{@value{GDBTUI}}. Do not use this option if you run @value{GDBN} from |
| 1160 | Emacs (@pxref{Emacs, ,Using @value{GDBN} under @sc{gnu} Emacs}). |
| 1161 | |
| 1162 | @c @item -xdb |
| 1163 | @c @cindex @code{--xdb} |
| 1164 | @c Run in XDB compatibility mode, allowing the use of certain XDB commands. |
| 1165 | @c For information, see the file @file{xdb_trans.html}, which is usually |
| 1166 | @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX |
| 1167 | @c systems. |
| 1168 | |
| 1169 | @item -interpreter @var{interp} |
| 1170 | @cindex @code{--interpreter} |
| 1171 | Use the interpreter @var{interp} for interface with the controlling |
| 1172 | program or device. This option is meant to be set by programs which |
| 1173 | communicate with @value{GDBN} using it as a back end. |
| 1174 | @xref{Interpreters, , Command Interpreters}. |
| 1175 | |
| 1176 | @samp{--interpreter=mi} (or @samp{--interpreter=mi2}) causes |
| 1177 | @value{GDBN} to use the @dfn{@sc{gdb/mi} interface} (@pxref{GDB/MI, , |
| 1178 | The @sc{gdb/mi} Interface}) included since @value{GDBN} version 6.0. The |
| 1179 | previous @sc{gdb/mi} interface, included in @value{GDBN} version 5.3 and |
| 1180 | selected with @samp{--interpreter=mi1}, is deprecated. Earlier |
| 1181 | @sc{gdb/mi} interfaces are no longer supported. |
| 1182 | |
| 1183 | @item -write |
| 1184 | @cindex @code{--write} |
| 1185 | Open the executable and core files for both reading and writing. This |
| 1186 | is equivalent to the @samp{set write on} command inside @value{GDBN} |
| 1187 | (@pxref{Patching}). |
| 1188 | |
| 1189 | @item -statistics |
| 1190 | @cindex @code{--statistics} |
| 1191 | This option causes @value{GDBN} to print statistics about time and |
| 1192 | memory usage after it completes each command and returns to the prompt. |
| 1193 | |
| 1194 | @item -version |
| 1195 | @cindex @code{--version} |
| 1196 | This option causes @value{GDBN} to print its version number and |
| 1197 | no-warranty blurb, and exit. |
| 1198 | |
| 1199 | @end table |
| 1200 | |
| 1201 | @node Startup |
| 1202 | @subsection What @value{GDBN} Does During Startup |
| 1203 | @cindex @value{GDBN} startup |
| 1204 | |
| 1205 | Here's the description of what @value{GDBN} does during session startup: |
| 1206 | |
| 1207 | @enumerate |
| 1208 | @item |
| 1209 | Sets up the command interpreter as specified by the command line |
| 1210 | (@pxref{Mode Options, interpreter}). |
| 1211 | |
| 1212 | @item |
| 1213 | @cindex init file |
| 1214 | Reads the system-wide @dfn{init file} (if @option{--with-system-gdbinit} was |
| 1215 | used when building @value{GDBN}; @pxref{System-wide configuration, |
| 1216 | ,System-wide configuration and settings}) and executes all the commands in |
| 1217 | that file. |
| 1218 | |
| 1219 | @item |
| 1220 | Reads the init file (if any) in your home directory@footnote{On |
| 1221 | DOS/Windows systems, the home directory is the one pointed to by the |
| 1222 | @code{HOME} environment variable.} and executes all the commands in |
| 1223 | that file. |
| 1224 | |
| 1225 | @item |
| 1226 | Processes command line options and operands. |
| 1227 | |
| 1228 | @item |
| 1229 | Reads and executes the commands from init file (if any) in the current |
| 1230 | working directory. This is only done if the current directory is |
| 1231 | different from your home directory. Thus, you can have more than one |
| 1232 | init file, one generic in your home directory, and another, specific |
| 1233 | to the program you are debugging, in the directory where you invoke |
| 1234 | @value{GDBN}. |
| 1235 | |
| 1236 | @item |
| 1237 | Reads command files specified by the @samp{-x} option. @xref{Command |
| 1238 | Files}, for more details about @value{GDBN} command files. |
| 1239 | |
| 1240 | @item |
| 1241 | Reads the command history recorded in the @dfn{history file}. |
| 1242 | @xref{Command History}, for more details about the command history and the |
| 1243 | files where @value{GDBN} records it. |
| 1244 | @end enumerate |
| 1245 | |
| 1246 | Init files use the same syntax as @dfn{command files} (@pxref{Command |
| 1247 | Files}) and are processed by @value{GDBN} in the same way. The init |
| 1248 | file in your home directory can set options (such as @samp{set |
| 1249 | complaints}) that affect subsequent processing of command line options |
| 1250 | and operands. Init files are not executed if you use the @samp{-nx} |
| 1251 | option (@pxref{Mode Options, ,Choosing Modes}). |
| 1252 | |
| 1253 | To display the list of init files loaded by gdb at startup, you |
| 1254 | can use @kbd{gdb --help}. |
| 1255 | |
| 1256 | @cindex init file name |
| 1257 | @cindex @file{.gdbinit} |
| 1258 | @cindex @file{gdb.ini} |
| 1259 | The @value{GDBN} init files are normally called @file{.gdbinit}. |
| 1260 | The DJGPP port of @value{GDBN} uses the name @file{gdb.ini}, due to |
| 1261 | the limitations of file names imposed by DOS filesystems. The Windows |
| 1262 | ports of @value{GDBN} use the standard name, but if they find a |
| 1263 | @file{gdb.ini} file, they warn you about that and suggest to rename |
| 1264 | the file to the standard name. |
| 1265 | |
| 1266 | |
| 1267 | @node Quitting GDB |
| 1268 | @section Quitting @value{GDBN} |
| 1269 | @cindex exiting @value{GDBN} |
| 1270 | @cindex leaving @value{GDBN} |
| 1271 | |
| 1272 | @table @code |
| 1273 | @kindex quit @r{[}@var{expression}@r{]} |
| 1274 | @kindex q @r{(@code{quit})} |
| 1275 | @item quit @r{[}@var{expression}@r{]} |
| 1276 | @itemx q |
| 1277 | To exit @value{GDBN}, use the @code{quit} command (abbreviated |
| 1278 | @code{q}), or type an end-of-file character (usually @kbd{Ctrl-d}). If you |
| 1279 | do not supply @var{expression}, @value{GDBN} will terminate normally; |
| 1280 | otherwise it will terminate using the result of @var{expression} as the |
| 1281 | error code. |
| 1282 | @end table |
| 1283 | |
| 1284 | @cindex interrupt |
| 1285 | An interrupt (often @kbd{Ctrl-c}) does not exit from @value{GDBN}, but rather |
| 1286 | terminates the action of any @value{GDBN} command that is in progress and |
| 1287 | returns to @value{GDBN} command level. It is safe to type the interrupt |
| 1288 | character at any time because @value{GDBN} does not allow it to take effect |
| 1289 | until a time when it is safe. |
| 1290 | |
| 1291 | If you have been using @value{GDBN} to control an attached process or |
| 1292 | device, you can release it with the @code{detach} command |
| 1293 | (@pxref{Attach, ,Debugging an Already-running Process}). |
| 1294 | |
| 1295 | @node Shell Commands |
| 1296 | @section Shell Commands |
| 1297 | |
| 1298 | If you need to execute occasional shell commands during your |
| 1299 | debugging session, there is no need to leave or suspend @value{GDBN}; you can |
| 1300 | just use the @code{shell} command. |
| 1301 | |
| 1302 | @table @code |
| 1303 | @kindex shell |
| 1304 | @cindex shell escape |
| 1305 | @item shell @var{command string} |
| 1306 | Invoke a standard shell to execute @var{command string}. |
| 1307 | If it exists, the environment variable @code{SHELL} determines which |
| 1308 | shell to run. Otherwise @value{GDBN} uses the default shell |
| 1309 | (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.). |
| 1310 | @end table |
| 1311 | |
| 1312 | The utility @code{make} is often needed in development environments. |
| 1313 | You do not have to use the @code{shell} command for this purpose in |
| 1314 | @value{GDBN}: |
| 1315 | |
| 1316 | @table @code |
| 1317 | @kindex make |
| 1318 | @cindex calling make |
| 1319 | @item make @var{make-args} |
| 1320 | Execute the @code{make} program with the specified |
| 1321 | arguments. This is equivalent to @samp{shell make @var{make-args}}. |
| 1322 | @end table |
| 1323 | |
| 1324 | @node Logging Output |
| 1325 | @section Logging Output |
| 1326 | @cindex logging @value{GDBN} output |
| 1327 | @cindex save @value{GDBN} output to a file |
| 1328 | |
| 1329 | You may want to save the output of @value{GDBN} commands to a file. |
| 1330 | There are several commands to control @value{GDBN}'s logging. |
| 1331 | |
| 1332 | @table @code |
| 1333 | @kindex set logging |
| 1334 | @item set logging on |
| 1335 | Enable logging. |
| 1336 | @item set logging off |
| 1337 | Disable logging. |
| 1338 | @cindex logging file name |
| 1339 | @item set logging file @var{file} |
| 1340 | Change the name of the current logfile. The default logfile is @file{gdb.txt}. |
| 1341 | @item set logging overwrite [on|off] |
| 1342 | By default, @value{GDBN} will append to the logfile. Set @code{overwrite} if |
| 1343 | you want @code{set logging on} to overwrite the logfile instead. |
| 1344 | @item set logging redirect [on|off] |
| 1345 | By default, @value{GDBN} output will go to both the terminal and the logfile. |
| 1346 | Set @code{redirect} if you want output to go only to the log file. |
| 1347 | @kindex show logging |
| 1348 | @item show logging |
| 1349 | Show the current values of the logging settings. |
| 1350 | @end table |
| 1351 | |
| 1352 | @node Commands |
| 1353 | @chapter @value{GDBN} Commands |
| 1354 | |
| 1355 | You can abbreviate a @value{GDBN} command to the first few letters of the command |
| 1356 | name, if that abbreviation is unambiguous; and you can repeat certain |
| 1357 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} |
| 1358 | key to get @value{GDBN} to fill out the rest of a word in a command (or to |
| 1359 | show you the alternatives available, if there is more than one possibility). |
| 1360 | |
| 1361 | @menu |
| 1362 | * Command Syntax:: How to give commands to @value{GDBN} |
| 1363 | * Completion:: Command completion |
| 1364 | * Help:: How to ask @value{GDBN} for help |
| 1365 | @end menu |
| 1366 | |
| 1367 | @node Command Syntax |
| 1368 | @section Command Syntax |
| 1369 | |
| 1370 | A @value{GDBN} command is a single line of input. There is no limit on |
| 1371 | how long it can be. It starts with a command name, which is followed by |
| 1372 | arguments whose meaning depends on the command name. For example, the |
| 1373 | command @code{step} accepts an argument which is the number of times to |
| 1374 | step, as in @samp{step 5}. You can also use the @code{step} command |
| 1375 | with no arguments. Some commands do not allow any arguments. |
| 1376 | |
| 1377 | @cindex abbreviation |
| 1378 | @value{GDBN} command names may always be truncated if that abbreviation is |
| 1379 | unambiguous. Other possible command abbreviations are listed in the |
| 1380 | documentation for individual commands. In some cases, even ambiguous |
| 1381 | abbreviations are allowed; for example, @code{s} is specially defined as |
| 1382 | equivalent to @code{step} even though there are other commands whose |
| 1383 | names start with @code{s}. You can test abbreviations by using them as |
| 1384 | arguments to the @code{help} command. |
| 1385 | |
| 1386 | @cindex repeating commands |
| 1387 | @kindex RET @r{(repeat last command)} |
| 1388 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to |
| 1389 | repeat the previous command. Certain commands (for example, @code{run}) |
| 1390 | will not repeat this way; these are commands whose unintentional |
| 1391 | repetition might cause trouble and which you are unlikely to want to |
| 1392 | repeat. User-defined commands can disable this feature; see |
| 1393 | @ref{Define, dont-repeat}. |
| 1394 | |
| 1395 | The @code{list} and @code{x} commands, when you repeat them with |
| 1396 | @key{RET}, construct new arguments rather than repeating |
| 1397 | exactly as typed. This permits easy scanning of source or memory. |
| 1398 | |
| 1399 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy |
| 1400 | output, in a way similar to the common utility @code{more} |
| 1401 | (@pxref{Screen Size,,Screen Size}). Since it is easy to press one |
| 1402 | @key{RET} too many in this situation, @value{GDBN} disables command |
| 1403 | repetition after any command that generates this sort of display. |
| 1404 | |
| 1405 | @kindex # @r{(a comment)} |
| 1406 | @cindex comment |
| 1407 | Any text from a @kbd{#} to the end of the line is a comment; it does |
| 1408 | nothing. This is useful mainly in command files (@pxref{Command |
| 1409 | Files,,Command Files}). |
| 1410 | |
| 1411 | @cindex repeating command sequences |
| 1412 | @kindex Ctrl-o @r{(operate-and-get-next)} |
| 1413 | The @kbd{Ctrl-o} binding is useful for repeating a complex sequence of |
| 1414 | commands. This command accepts the current line, like @key{RET}, and |
| 1415 | then fetches the next line relative to the current line from the history |
| 1416 | for editing. |
| 1417 | |
| 1418 | @node Completion |
| 1419 | @section Command Completion |
| 1420 | |
| 1421 | @cindex completion |
| 1422 | @cindex word completion |
| 1423 | @value{GDBN} can fill in the rest of a word in a command for you, if there is |
| 1424 | only one possibility; it can also show you what the valid possibilities |
| 1425 | are for the next word in a command, at any time. This works for @value{GDBN} |
| 1426 | commands, @value{GDBN} subcommands, and the names of symbols in your program. |
| 1427 | |
| 1428 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest |
| 1429 | of a word. If there is only one possibility, @value{GDBN} fills in the |
| 1430 | word, and waits for you to finish the command (or press @key{RET} to |
| 1431 | enter it). For example, if you type |
| 1432 | |
| 1433 | @c FIXME "@key" does not distinguish its argument sufficiently to permit |
| 1434 | @c complete accuracy in these examples; space introduced for clarity. |
| 1435 | @c If texinfo enhancements make it unnecessary, it would be nice to |
| 1436 | @c replace " @key" by "@key" in the following... |
| 1437 | @smallexample |
| 1438 | (@value{GDBP}) info bre @key{TAB} |
| 1439 | @end smallexample |
| 1440 | |
| 1441 | @noindent |
| 1442 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is |
| 1443 | the only @code{info} subcommand beginning with @samp{bre}: |
| 1444 | |
| 1445 | @smallexample |
| 1446 | (@value{GDBP}) info breakpoints |
| 1447 | @end smallexample |
| 1448 | |
| 1449 | @noindent |
| 1450 | You can either press @key{RET} at this point, to run the @code{info |
| 1451 | breakpoints} command, or backspace and enter something else, if |
| 1452 | @samp{breakpoints} does not look like the command you expected. (If you |
| 1453 | were sure you wanted @code{info breakpoints} in the first place, you |
| 1454 | might as well just type @key{RET} immediately after @samp{info bre}, |
| 1455 | to exploit command abbreviations rather than command completion). |
| 1456 | |
| 1457 | If there is more than one possibility for the next word when you press |
| 1458 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more |
| 1459 | characters and try again, or just press @key{TAB} a second time; |
| 1460 | @value{GDBN} displays all the possible completions for that word. For |
| 1461 | example, you might want to set a breakpoint on a subroutine whose name |
| 1462 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} |
| 1463 | just sounds the bell. Typing @key{TAB} again displays all the |
| 1464 | function names in your program that begin with those characters, for |
| 1465 | example: |
| 1466 | |
| 1467 | @smallexample |
| 1468 | (@value{GDBP}) b make_ @key{TAB} |
| 1469 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: |
| 1470 | make_a_section_from_file make_environ |
| 1471 | make_abs_section make_function_type |
| 1472 | make_blockvector make_pointer_type |
| 1473 | make_cleanup make_reference_type |
| 1474 | make_command make_symbol_completion_list |
| 1475 | (@value{GDBP}) b make_ |
| 1476 | @end smallexample |
| 1477 | |
| 1478 | @noindent |
| 1479 | After displaying the available possibilities, @value{GDBN} copies your |
| 1480 | partial input (@samp{b make_} in the example) so you can finish the |
| 1481 | command. |
| 1482 | |
| 1483 | If you just want to see the list of alternatives in the first place, you |
| 1484 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} |
| 1485 | means @kbd{@key{META} ?}. You can type this either by holding down a |
| 1486 | key designated as the @key{META} shift on your keyboard (if there is |
| 1487 | one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}. |
| 1488 | |
| 1489 | @cindex quotes in commands |
| 1490 | @cindex completion of quoted strings |
| 1491 | Sometimes the string you need, while logically a ``word'', may contain |
| 1492 | parentheses or other characters that @value{GDBN} normally excludes from |
| 1493 | its notion of a word. To permit word completion to work in this |
| 1494 | situation, you may enclose words in @code{'} (single quote marks) in |
| 1495 | @value{GDBN} commands. |
| 1496 | |
| 1497 | The most likely situation where you might need this is in typing the |
| 1498 | name of a C@t{++} function. This is because C@t{++} allows function |
| 1499 | overloading (multiple definitions of the same function, distinguished |
| 1500 | by argument type). For example, when you want to set a breakpoint you |
| 1501 | may need to distinguish whether you mean the version of @code{name} |
| 1502 | that takes an @code{int} parameter, @code{name(int)}, or the version |
| 1503 | that takes a @code{float} parameter, @code{name(float)}. To use the |
| 1504 | word-completion facilities in this situation, type a single quote |
| 1505 | @code{'} at the beginning of the function name. This alerts |
| 1506 | @value{GDBN} that it may need to consider more information than usual |
| 1507 | when you press @key{TAB} or @kbd{M-?} to request word completion: |
| 1508 | |
| 1509 | @smallexample |
| 1510 | (@value{GDBP}) b 'bubble( @kbd{M-?} |
| 1511 | bubble(double,double) bubble(int,int) |
| 1512 | (@value{GDBP}) b 'bubble( |
| 1513 | @end smallexample |
| 1514 | |
| 1515 | In some cases, @value{GDBN} can tell that completing a name requires using |
| 1516 | quotes. When this happens, @value{GDBN} inserts the quote for you (while |
| 1517 | completing as much as it can) if you do not type the quote in the first |
| 1518 | place: |
| 1519 | |
| 1520 | @smallexample |
| 1521 | (@value{GDBP}) b bub @key{TAB} |
| 1522 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: |
| 1523 | (@value{GDBP}) b 'bubble( |
| 1524 | @end smallexample |
| 1525 | |
| 1526 | @noindent |
| 1527 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if |
| 1528 | you have not yet started typing the argument list when you ask for |
| 1529 | completion on an overloaded symbol. |
| 1530 | |
| 1531 | For more information about overloaded functions, see @ref{C Plus Plus |
| 1532 | Expressions, ,C@t{++} Expressions}. You can use the command @code{set |
| 1533 | overload-resolution off} to disable overload resolution; |
| 1534 | see @ref{Debugging C Plus Plus, ,@value{GDBN} Features for C@t{++}}. |
| 1535 | |
| 1536 | @cindex completion of structure field names |
| 1537 | @cindex structure field name completion |
| 1538 | @cindex completion of union field names |
| 1539 | @cindex union field name completion |
| 1540 | When completing in an expression which looks up a field in a |
| 1541 | structure, @value{GDBN} also tries@footnote{The completer can be |
| 1542 | confused by certain kinds of invalid expressions. Also, it only |
| 1543 | examines the static type of the expression, not the dynamic type.} to |
| 1544 | limit completions to the field names available in the type of the |
| 1545 | left-hand-side: |
| 1546 | |
| 1547 | @smallexample |
| 1548 | (@value{GDBP}) p gdb_stdout.@kbd{M-?} |
| 1549 | magic to_delete to_fputs to_put to_rewind |
| 1550 | to_data to_flush to_isatty to_read to_write |
| 1551 | @end smallexample |
| 1552 | |
| 1553 | @noindent |
| 1554 | This is because the @code{gdb_stdout} is a variable of the type |
| 1555 | @code{struct ui_file} that is defined in @value{GDBN} sources as |
| 1556 | follows: |
| 1557 | |
| 1558 | @smallexample |
| 1559 | struct ui_file |
| 1560 | @{ |
| 1561 | int *magic; |
| 1562 | ui_file_flush_ftype *to_flush; |
| 1563 | ui_file_write_ftype *to_write; |
| 1564 | ui_file_fputs_ftype *to_fputs; |
| 1565 | ui_file_read_ftype *to_read; |
| 1566 | ui_file_delete_ftype *to_delete; |
| 1567 | ui_file_isatty_ftype *to_isatty; |
| 1568 | ui_file_rewind_ftype *to_rewind; |
| 1569 | ui_file_put_ftype *to_put; |
| 1570 | void *to_data; |
| 1571 | @} |
| 1572 | @end smallexample |
| 1573 | |
| 1574 | |
| 1575 | @node Help |
| 1576 | @section Getting Help |
| 1577 | @cindex online documentation |
| 1578 | @kindex help |
| 1579 | |
| 1580 | You can always ask @value{GDBN} itself for information on its commands, |
| 1581 | using the command @code{help}. |
| 1582 | |
| 1583 | @table @code |
| 1584 | @kindex h @r{(@code{help})} |
| 1585 | @item help |
| 1586 | @itemx h |
| 1587 | You can use @code{help} (abbreviated @code{h}) with no arguments to |
| 1588 | display a short list of named classes of commands: |
| 1589 | |
| 1590 | @smallexample |
| 1591 | (@value{GDBP}) help |
| 1592 | List of classes of commands: |
| 1593 | |
| 1594 | aliases -- Aliases of other commands |
| 1595 | breakpoints -- Making program stop at certain points |
| 1596 | data -- Examining data |
| 1597 | files -- Specifying and examining files |
| 1598 | internals -- Maintenance commands |
| 1599 | obscure -- Obscure features |
| 1600 | running -- Running the program |
| 1601 | stack -- Examining the stack |
| 1602 | status -- Status inquiries |
| 1603 | support -- Support facilities |
| 1604 | tracepoints -- Tracing of program execution without |
| 1605 | stopping the program |
| 1606 | user-defined -- User-defined commands |
| 1607 | |
| 1608 | Type "help" followed by a class name for a list of |
| 1609 | commands in that class. |
| 1610 | Type "help" followed by command name for full |
| 1611 | documentation. |
| 1612 | Command name abbreviations are allowed if unambiguous. |
| 1613 | (@value{GDBP}) |
| 1614 | @end smallexample |
| 1615 | @c the above line break eliminates huge line overfull... |
| 1616 | |
| 1617 | @item help @var{class} |
| 1618 | Using one of the general help classes as an argument, you can get a |
| 1619 | list of the individual commands in that class. For example, here is the |
| 1620 | help display for the class @code{status}: |
| 1621 | |
| 1622 | @smallexample |
| 1623 | (@value{GDBP}) help status |
| 1624 | Status inquiries. |
| 1625 | |
| 1626 | List of commands: |
| 1627 | |
| 1628 | @c Line break in "show" line falsifies real output, but needed |
| 1629 | @c to fit in smallbook page size. |
| 1630 | info -- Generic command for showing things |
| 1631 | about the program being debugged |
| 1632 | show -- Generic command for showing things |
| 1633 | about the debugger |
| 1634 | |
| 1635 | Type "help" followed by command name for full |
| 1636 | documentation. |
| 1637 | Command name abbreviations are allowed if unambiguous. |
| 1638 | (@value{GDBP}) |
| 1639 | @end smallexample |
| 1640 | |
| 1641 | @item help @var{command} |
| 1642 | With a command name as @code{help} argument, @value{GDBN} displays a |
| 1643 | short paragraph on how to use that command. |
| 1644 | |
| 1645 | @kindex apropos |
| 1646 | @item apropos @var{args} |
| 1647 | The @code{apropos} command searches through all of the @value{GDBN} |
| 1648 | commands, and their documentation, for the regular expression specified in |
| 1649 | @var{args}. It prints out all matches found. For example: |
| 1650 | |
| 1651 | @smallexample |
| 1652 | apropos reload |
| 1653 | @end smallexample |
| 1654 | |
| 1655 | @noindent |
| 1656 | results in: |
| 1657 | |
| 1658 | @smallexample |
| 1659 | @c @group |
| 1660 | set symbol-reloading -- Set dynamic symbol table reloading |
| 1661 | multiple times in one run |
| 1662 | show symbol-reloading -- Show dynamic symbol table reloading |
| 1663 | multiple times in one run |
| 1664 | @c @end group |
| 1665 | @end smallexample |
| 1666 | |
| 1667 | @kindex complete |
| 1668 | @item complete @var{args} |
| 1669 | The @code{complete @var{args}} command lists all the possible completions |
| 1670 | for the beginning of a command. Use @var{args} to specify the beginning of the |
| 1671 | command you want completed. For example: |
| 1672 | |
| 1673 | @smallexample |
| 1674 | complete i |
| 1675 | @end smallexample |
| 1676 | |
| 1677 | @noindent results in: |
| 1678 | |
| 1679 | @smallexample |
| 1680 | @group |
| 1681 | if |
| 1682 | ignore |
| 1683 | info |
| 1684 | inspect |
| 1685 | @end group |
| 1686 | @end smallexample |
| 1687 | |
| 1688 | @noindent This is intended for use by @sc{gnu} Emacs. |
| 1689 | @end table |
| 1690 | |
| 1691 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} |
| 1692 | and @code{show} to inquire about the state of your program, or the state |
| 1693 | of @value{GDBN} itself. Each command supports many topics of inquiry; this |
| 1694 | manual introduces each of them in the appropriate context. The listings |
| 1695 | under @code{info} and under @code{show} in the Index point to |
| 1696 | all the sub-commands. @xref{Index}. |
| 1697 | |
| 1698 | @c @group |
| 1699 | @table @code |
| 1700 | @kindex info |
| 1701 | @kindex i @r{(@code{info})} |
| 1702 | @item info |
| 1703 | This command (abbreviated @code{i}) is for describing the state of your |
| 1704 | program. For example, you can show the arguments passed to a function |
| 1705 | with @code{info args}, list the registers currently in use with @code{info |
| 1706 | registers}, or list the breakpoints you have set with @code{info breakpoints}. |
| 1707 | You can get a complete list of the @code{info} sub-commands with |
| 1708 | @w{@code{help info}}. |
| 1709 | |
| 1710 | @kindex set |
| 1711 | @item set |
| 1712 | You can assign the result of an expression to an environment variable with |
| 1713 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with |
| 1714 | @code{set prompt $}. |
| 1715 | |
| 1716 | @kindex show |
| 1717 | @item show |
| 1718 | In contrast to @code{info}, @code{show} is for describing the state of |
| 1719 | @value{GDBN} itself. |
| 1720 | You can change most of the things you can @code{show}, by using the |
| 1721 | related command @code{set}; for example, you can control what number |
| 1722 | system is used for displays with @code{set radix}, or simply inquire |
| 1723 | which is currently in use with @code{show radix}. |
| 1724 | |
| 1725 | @kindex info set |
| 1726 | To display all the settable parameters and their current |
| 1727 | values, you can use @code{show} with no arguments; you may also use |
| 1728 | @code{info set}. Both commands produce the same display. |
| 1729 | @c FIXME: "info set" violates the rule that "info" is for state of |
| 1730 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, |
| 1731 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? |
| 1732 | @end table |
| 1733 | @c @end group |
| 1734 | |
| 1735 | Here are three miscellaneous @code{show} subcommands, all of which are |
| 1736 | exceptional in lacking corresponding @code{set} commands: |
| 1737 | |
| 1738 | @table @code |
| 1739 | @kindex show version |
| 1740 | @cindex @value{GDBN} version number |
| 1741 | @item show version |
| 1742 | Show what version of @value{GDBN} is running. You should include this |
| 1743 | information in @value{GDBN} bug-reports. If multiple versions of |
| 1744 | @value{GDBN} are in use at your site, you may need to determine which |
| 1745 | version of @value{GDBN} you are running; as @value{GDBN} evolves, new |
| 1746 | commands are introduced, and old ones may wither away. Also, many |
| 1747 | system vendors ship variant versions of @value{GDBN}, and there are |
| 1748 | variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well. |
| 1749 | The version number is the same as the one announced when you start |
| 1750 | @value{GDBN}. |
| 1751 | |
| 1752 | @kindex show copying |
| 1753 | @kindex info copying |
| 1754 | @cindex display @value{GDBN} copyright |
| 1755 | @item show copying |
| 1756 | @itemx info copying |
| 1757 | Display information about permission for copying @value{GDBN}. |
| 1758 | |
| 1759 | @kindex show warranty |
| 1760 | @kindex info warranty |
| 1761 | @item show warranty |
| 1762 | @itemx info warranty |
| 1763 | Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty, |
| 1764 | if your version of @value{GDBN} comes with one. |
| 1765 | |
| 1766 | @end table |
| 1767 | |
| 1768 | @node Running |
| 1769 | @chapter Running Programs Under @value{GDBN} |
| 1770 | |
| 1771 | When you run a program under @value{GDBN}, you must first generate |
| 1772 | debugging information when you compile it. |
| 1773 | |
| 1774 | You may start @value{GDBN} with its arguments, if any, in an environment |
| 1775 | of your choice. If you are doing native debugging, you may redirect |
| 1776 | your program's input and output, debug an already running process, or |
| 1777 | kill a child process. |
| 1778 | |
| 1779 | @menu |
| 1780 | * Compilation:: Compiling for debugging |
| 1781 | * Starting:: Starting your program |
| 1782 | * Arguments:: Your program's arguments |
| 1783 | * Environment:: Your program's environment |
| 1784 | |
| 1785 | * Working Directory:: Your program's working directory |
| 1786 | * Input/Output:: Your program's input and output |
| 1787 | * Attach:: Debugging an already-running process |
| 1788 | * Kill Process:: Killing the child process |
| 1789 | |
| 1790 | * Inferiors:: Debugging multiple inferiors |
| 1791 | * Threads:: Debugging programs with multiple threads |
| 1792 | * Processes:: Debugging programs with multiple processes |
| 1793 | * Checkpoint/Restart:: Setting a @emph{bookmark} to return to later |
| 1794 | @end menu |
| 1795 | |
| 1796 | @node Compilation |
| 1797 | @section Compiling for Debugging |
| 1798 | |
| 1799 | In order to debug a program effectively, you need to generate |
| 1800 | debugging information when you compile it. This debugging information |
| 1801 | is stored in the object file; it describes the data type of each |
| 1802 | variable or function and the correspondence between source line numbers |
| 1803 | and addresses in the executable code. |
| 1804 | |
| 1805 | To request debugging information, specify the @samp{-g} option when you run |
| 1806 | the compiler. |
| 1807 | |
| 1808 | Programs that are to be shipped to your customers are compiled with |
| 1809 | optimizations, using the @samp{-O} compiler option. However, many |
| 1810 | compilers are unable to handle the @samp{-g} and @samp{-O} options |
| 1811 | together. Using those compilers, you cannot generate optimized |
| 1812 | executables containing debugging information. |
| 1813 | |
| 1814 | @value{NGCC}, the @sc{gnu} C/C@t{++} compiler, supports @samp{-g} with or |
| 1815 | without @samp{-O}, making it possible to debug optimized code. We |
| 1816 | recommend that you @emph{always} use @samp{-g} whenever you compile a |
| 1817 | program. You may think your program is correct, but there is no sense |
| 1818 | in pushing your luck. |
| 1819 | |
| 1820 | @cindex optimized code, debugging |
| 1821 | @cindex debugging optimized code |
| 1822 | When you debug a program compiled with @samp{-g -O}, remember that the |
| 1823 | optimizer is rearranging your code; the debugger shows you what is |
| 1824 | really there. Do not be too surprised when the execution path does not |
| 1825 | exactly match your source file! An extreme example: if you define a |
| 1826 | variable, but never use it, @value{GDBN} never sees that |
| 1827 | variable---because the compiler optimizes it out of existence. |
| 1828 | |
| 1829 | Some things do not work as well with @samp{-g -O} as with just |
| 1830 | @samp{-g}, particularly on machines with instruction scheduling. If in |
| 1831 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, |
| 1832 | please report it to us as a bug (including a test case!). |
| 1833 | @xref{Variables}, for more information about debugging optimized code. |
| 1834 | |
| 1835 | Older versions of the @sc{gnu} C compiler permitted a variant option |
| 1836 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this |
| 1837 | format; if your @sc{gnu} C compiler has this option, do not use it. |
| 1838 | |
| 1839 | @value{GDBN} knows about preprocessor macros and can show you their |
| 1840 | expansion (@pxref{Macros}). Most compilers do not include information |
| 1841 | about preprocessor macros in the debugging information if you specify |
| 1842 | the @option{-g} flag alone, because this information is rather large. |
| 1843 | Version 3.1 and later of @value{NGCC}, the @sc{gnu} C compiler, |
| 1844 | provides macro information if you specify the options |
| 1845 | @option{-gdwarf-2} and @option{-g3}; the former option requests |
| 1846 | debugging information in the Dwarf 2 format, and the latter requests |
| 1847 | ``extra information''. In the future, we hope to find more compact |
| 1848 | ways to represent macro information, so that it can be included with |
| 1849 | @option{-g} alone. |
| 1850 | |
| 1851 | @need 2000 |
| 1852 | @node Starting |
| 1853 | @section Starting your Program |
| 1854 | @cindex starting |
| 1855 | @cindex running |
| 1856 | |
| 1857 | @table @code |
| 1858 | @kindex run |
| 1859 | @kindex r @r{(@code{run})} |
| 1860 | @item run |
| 1861 | @itemx r |
| 1862 | Use the @code{run} command to start your program under @value{GDBN}. |
| 1863 | You must first specify the program name (except on VxWorks) with an |
| 1864 | argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of |
| 1865 | @value{GDBN}}), or by using the @code{file} or @code{exec-file} command |
| 1866 | (@pxref{Files, ,Commands to Specify Files}). |
| 1867 | |
| 1868 | @end table |
| 1869 | |
| 1870 | If you are running your program in an execution environment that |
| 1871 | supports processes, @code{run} creates an inferior process and makes |
| 1872 | that process run your program. In some environments without processes, |
| 1873 | @code{run} jumps to the start of your program. Other targets, |
| 1874 | like @samp{remote}, are always running. If you get an error |
| 1875 | message like this one: |
| 1876 | |
| 1877 | @smallexample |
| 1878 | The "remote" target does not support "run". |
| 1879 | Try "help target" or "continue". |
| 1880 | @end smallexample |
| 1881 | |
| 1882 | @noindent |
| 1883 | then use @code{continue} to run your program. You may need @code{load} |
| 1884 | first (@pxref{load}). |
| 1885 | |
| 1886 | The execution of a program is affected by certain information it |
| 1887 | receives from its superior. @value{GDBN} provides ways to specify this |
| 1888 | information, which you must do @emph{before} starting your program. (You |
| 1889 | can change it after starting your program, but such changes only affect |
| 1890 | your program the next time you start it.) This information may be |
| 1891 | divided into four categories: |
| 1892 | |
| 1893 | @table @asis |
| 1894 | @item The @emph{arguments.} |
| 1895 | Specify the arguments to give your program as the arguments of the |
| 1896 | @code{run} command. If a shell is available on your target, the shell |
| 1897 | is used to pass the arguments, so that you may use normal conventions |
| 1898 | (such as wildcard expansion or variable substitution) in describing |
| 1899 | the arguments. |
| 1900 | In Unix systems, you can control which shell is used with the |
| 1901 | @code{SHELL} environment variable. |
| 1902 | @xref{Arguments, ,Your Program's Arguments}. |
| 1903 | |
| 1904 | @item The @emph{environment.} |
| 1905 | Your program normally inherits its environment from @value{GDBN}, but you can |
| 1906 | use the @value{GDBN} commands @code{set environment} and @code{unset |
| 1907 | environment} to change parts of the environment that affect |
| 1908 | your program. @xref{Environment, ,Your Program's Environment}. |
| 1909 | |
| 1910 | @item The @emph{working directory.} |
| 1911 | Your program inherits its working directory from @value{GDBN}. You can set |
| 1912 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. |
| 1913 | @xref{Working Directory, ,Your Program's Working Directory}. |
| 1914 | |
| 1915 | @item The @emph{standard input and output.} |
| 1916 | Your program normally uses the same device for standard input and |
| 1917 | standard output as @value{GDBN} is using. You can redirect input and output |
| 1918 | in the @code{run} command line, or you can use the @code{tty} command to |
| 1919 | set a different device for your program. |
| 1920 | @xref{Input/Output, ,Your Program's Input and Output}. |
| 1921 | |
| 1922 | @cindex pipes |
| 1923 | @emph{Warning:} While input and output redirection work, you cannot use |
| 1924 | pipes to pass the output of the program you are debugging to another |
| 1925 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the |
| 1926 | wrong program. |
| 1927 | @end table |
| 1928 | |
| 1929 | When you issue the @code{run} command, your program begins to execute |
| 1930 | immediately. @xref{Stopping, ,Stopping and Continuing}, for discussion |
| 1931 | of how to arrange for your program to stop. Once your program has |
| 1932 | stopped, you may call functions in your program, using the @code{print} |
| 1933 | or @code{call} commands. @xref{Data, ,Examining Data}. |
| 1934 | |
| 1935 | If the modification time of your symbol file has changed since the last |
| 1936 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol |
| 1937 | table, and reads it again. When it does this, @value{GDBN} tries to retain |
| 1938 | your current breakpoints. |
| 1939 | |
| 1940 | @table @code |
| 1941 | @kindex start |
| 1942 | @item start |
| 1943 | @cindex run to main procedure |
| 1944 | The name of the main procedure can vary from language to language. |
| 1945 | With C or C@t{++}, the main procedure name is always @code{main}, but |
| 1946 | other languages such as Ada do not require a specific name for their |
| 1947 | main procedure. The debugger provides a convenient way to start the |
| 1948 | execution of the program and to stop at the beginning of the main |
| 1949 | procedure, depending on the language used. |
| 1950 | |
| 1951 | The @samp{start} command does the equivalent of setting a temporary |
| 1952 | breakpoint at the beginning of the main procedure and then invoking |
| 1953 | the @samp{run} command. |
| 1954 | |
| 1955 | @cindex elaboration phase |
| 1956 | Some programs contain an @dfn{elaboration} phase where some startup code is |
| 1957 | executed before the main procedure is called. This depends on the |
| 1958 | languages used to write your program. In C@t{++}, for instance, |
| 1959 | constructors for static and global objects are executed before |
| 1960 | @code{main} is called. It is therefore possible that the debugger stops |
| 1961 | before reaching the main procedure. However, the temporary breakpoint |
| 1962 | will remain to halt execution. |
| 1963 | |
| 1964 | Specify the arguments to give to your program as arguments to the |
| 1965 | @samp{start} command. These arguments will be given verbatim to the |
| 1966 | underlying @samp{run} command. Note that the same arguments will be |
| 1967 | reused if no argument is provided during subsequent calls to |
| 1968 | @samp{start} or @samp{run}. |
| 1969 | |
| 1970 | It is sometimes necessary to debug the program during elaboration. In |
| 1971 | these cases, using the @code{start} command would stop the execution of |
| 1972 | your program too late, as the program would have already completed the |
| 1973 | elaboration phase. Under these circumstances, insert breakpoints in your |
| 1974 | elaboration code before running your program. |
| 1975 | |
| 1976 | @kindex set exec-wrapper |
| 1977 | @item set exec-wrapper @var{wrapper} |
| 1978 | @itemx show exec-wrapper |
| 1979 | @itemx unset exec-wrapper |
| 1980 | When @samp{exec-wrapper} is set, the specified wrapper is used to |
| 1981 | launch programs for debugging. @value{GDBN} starts your program |
| 1982 | with a shell command of the form @kbd{exec @var{wrapper} |
| 1983 | @var{program}}. Quoting is added to @var{program} and its |
| 1984 | arguments, but not to @var{wrapper}, so you should add quotes if |
| 1985 | appropriate for your shell. The wrapper runs until it executes |
| 1986 | your program, and then @value{GDBN} takes control. |
| 1987 | |
| 1988 | You can use any program that eventually calls @code{execve} with |
| 1989 | its arguments as a wrapper. Several standard Unix utilities do |
| 1990 | this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending |
| 1991 | with @code{exec "$@@"} will also work. |
| 1992 | |
| 1993 | For example, you can use @code{env} to pass an environment variable to |
| 1994 | the debugged program, without setting the variable in your shell's |
| 1995 | environment: |
| 1996 | |
| 1997 | @smallexample |
| 1998 | (@value{GDBP}) set exec-wrapper env 'LD_PRELOAD=libtest.so' |
| 1999 | (@value{GDBP}) run |
| 2000 | @end smallexample |
| 2001 | |
| 2002 | This command is available when debugging locally on most targets, excluding |
| 2003 | @sc{djgpp}, Cygwin, MS Windows, and QNX Neutrino. |
| 2004 | |
| 2005 | @kindex set disable-randomization |
| 2006 | @item set disable-randomization |
| 2007 | @itemx set disable-randomization on |
| 2008 | This option (enabled by default in @value{GDBN}) will turn off the native |
| 2009 | randomization of the virtual address space of the started program. This option |
| 2010 | is useful for multiple debugging sessions to make the execution better |
| 2011 | reproducible and memory addresses reusable across debugging sessions. |
| 2012 | |
| 2013 | This feature is implemented only on @sc{gnu}/Linux. You can get the same |
| 2014 | behavior using |
| 2015 | |
| 2016 | @smallexample |
| 2017 | (@value{GDBP}) set exec-wrapper setarch `uname -m` -R |
| 2018 | @end smallexample |
| 2019 | |
| 2020 | @item set disable-randomization off |
| 2021 | Leave the behavior of the started executable unchanged. Some bugs rear their |
| 2022 | ugly heads only when the program is loaded at certain addresses. If your bug |
| 2023 | disappears when you run the program under @value{GDBN}, that might be because |
| 2024 | @value{GDBN} by default disables the address randomization on platforms, such |
| 2025 | as @sc{gnu}/Linux, which do that for stand-alone programs. Use @kbd{set |
| 2026 | disable-randomization off} to try to reproduce such elusive bugs. |
| 2027 | |
| 2028 | The virtual address space randomization is implemented only on @sc{gnu}/Linux. |
| 2029 | It protects the programs against some kinds of security attacks. In these |
| 2030 | cases the attacker needs to know the exact location of a concrete executable |
| 2031 | code. Randomizing its location makes it impossible to inject jumps misusing |
| 2032 | a code at its expected addresses. |
| 2033 | |
| 2034 | Prelinking shared libraries provides a startup performance advantage but it |
| 2035 | makes addresses in these libraries predictable for privileged processes by |
| 2036 | having just unprivileged access at the target system. Reading the shared |
| 2037 | library binary gives enough information for assembling the malicious code |
| 2038 | misusing it. Still even a prelinked shared library can get loaded at a new |
| 2039 | random address just requiring the regular relocation process during the |
| 2040 | startup. Shared libraries not already prelinked are always loaded at |
| 2041 | a randomly chosen address. |
| 2042 | |
| 2043 | Position independent executables (PIE) contain position independent code |
| 2044 | similar to the shared libraries and therefore such executables get loaded at |
| 2045 | a randomly chosen address upon startup. PIE executables always load even |
| 2046 | already prelinked shared libraries at a random address. You can build such |
| 2047 | executable using @command{gcc -fPIE -pie}. |
| 2048 | |
| 2049 | Heap (malloc storage), stack and custom mmap areas are always placed randomly |
| 2050 | (as long as the randomization is enabled). |
| 2051 | |
| 2052 | @item show disable-randomization |
| 2053 | Show the current setting of the explicit disable of the native randomization of |
| 2054 | the virtual address space of the started program. |
| 2055 | |
| 2056 | @end table |
| 2057 | |
| 2058 | @node Arguments |
| 2059 | @section Your Program's Arguments |
| 2060 | |
| 2061 | @cindex arguments (to your program) |
| 2062 | The arguments to your program can be specified by the arguments of the |
| 2063 | @code{run} command. |
| 2064 | They are passed to a shell, which expands wildcard characters and |
| 2065 | performs redirection of I/O, and thence to your program. Your |
| 2066 | @code{SHELL} environment variable (if it exists) specifies what shell |
| 2067 | @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses |
| 2068 | the default shell (@file{/bin/sh} on Unix). |
| 2069 | |
| 2070 | On non-Unix systems, the program is usually invoked directly by |
| 2071 | @value{GDBN}, which emulates I/O redirection via the appropriate system |
| 2072 | calls, and the wildcard characters are expanded by the startup code of |
| 2073 | the program, not by the shell. |
| 2074 | |
| 2075 | @code{run} with no arguments uses the same arguments used by the previous |
| 2076 | @code{run}, or those set by the @code{set args} command. |
| 2077 | |
| 2078 | @table @code |
| 2079 | @kindex set args |
| 2080 | @item set args |
| 2081 | Specify the arguments to be used the next time your program is run. If |
| 2082 | @code{set args} has no arguments, @code{run} executes your program |
| 2083 | with no arguments. Once you have run your program with arguments, |
| 2084 | using @code{set args} before the next @code{run} is the only way to run |
| 2085 | it again without arguments. |
| 2086 | |
| 2087 | @kindex show args |
| 2088 | @item show args |
| 2089 | Show the arguments to give your program when it is started. |
| 2090 | @end table |
| 2091 | |
| 2092 | @node Environment |
| 2093 | @section Your Program's Environment |
| 2094 | |
| 2095 | @cindex environment (of your program) |
| 2096 | The @dfn{environment} consists of a set of environment variables and |
| 2097 | their values. Environment variables conventionally record such things as |
| 2098 | your user name, your home directory, your terminal type, and your search |
| 2099 | path for programs to run. Usually you set up environment variables with |
| 2100 | the shell and they are inherited by all the other programs you run. When |
| 2101 | debugging, it can be useful to try running your program with a modified |
| 2102 | environment without having to start @value{GDBN} over again. |
| 2103 | |
| 2104 | @table @code |
| 2105 | @kindex path |
| 2106 | @item path @var{directory} |
| 2107 | Add @var{directory} to the front of the @code{PATH} environment variable |
| 2108 | (the search path for executables) that will be passed to your program. |
| 2109 | The value of @code{PATH} used by @value{GDBN} does not change. |
| 2110 | You may specify several directory names, separated by whitespace or by a |
| 2111 | system-dependent separator character (@samp{:} on Unix, @samp{;} on |
| 2112 | MS-DOS and MS-Windows). If @var{directory} is already in the path, it |
| 2113 | is moved to the front, so it is searched sooner. |
| 2114 | |
| 2115 | You can use the string @samp{$cwd} to refer to whatever is the current |
| 2116 | working directory at the time @value{GDBN} searches the path. If you |
| 2117 | use @samp{.} instead, it refers to the directory where you executed the |
| 2118 | @code{path} command. @value{GDBN} replaces @samp{.} in the |
| 2119 | @var{directory} argument (with the current path) before adding |
| 2120 | @var{directory} to the search path. |
| 2121 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to |
| 2122 | @c document that, since repeating it would be a no-op. |
| 2123 | |
| 2124 | @kindex show paths |
| 2125 | @item show paths |
| 2126 | Display the list of search paths for executables (the @code{PATH} |
| 2127 | environment variable). |
| 2128 | |
| 2129 | @kindex show environment |
| 2130 | @item show environment @r{[}@var{varname}@r{]} |
| 2131 | Print the value of environment variable @var{varname} to be given to |
| 2132 | your program when it starts. If you do not supply @var{varname}, |
| 2133 | print the names and values of all environment variables to be given to |
| 2134 | your program. You can abbreviate @code{environment} as @code{env}. |
| 2135 | |
| 2136 | @kindex set environment |
| 2137 | @item set environment @var{varname} @r{[}=@var{value}@r{]} |
| 2138 | Set environment variable @var{varname} to @var{value}. The value |
| 2139 | changes for your program only, not for @value{GDBN} itself. @var{value} may |
| 2140 | be any string; the values of environment variables are just strings, and |
| 2141 | any interpretation is supplied by your program itself. The @var{value} |
| 2142 | parameter is optional; if it is eliminated, the variable is set to a |
| 2143 | null value. |
| 2144 | @c "any string" here does not include leading, trailing |
| 2145 | @c blanks. Gnu asks: does anyone care? |
| 2146 | |
| 2147 | For example, this command: |
| 2148 | |
| 2149 | @smallexample |
| 2150 | set env USER = foo |
| 2151 | @end smallexample |
| 2152 | |
| 2153 | @noindent |
| 2154 | tells the debugged program, when subsequently run, that its user is named |
| 2155 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they |
| 2156 | are not actually required.) |
| 2157 | |
| 2158 | @kindex unset environment |
| 2159 | @item unset environment @var{varname} |
| 2160 | Remove variable @var{varname} from the environment to be passed to your |
| 2161 | program. This is different from @samp{set env @var{varname} =}; |
| 2162 | @code{unset environment} removes the variable from the environment, |
| 2163 | rather than assigning it an empty value. |
| 2164 | @end table |
| 2165 | |
| 2166 | @emph{Warning:} On Unix systems, @value{GDBN} runs your program using |
| 2167 | the shell indicated |
| 2168 | by your @code{SHELL} environment variable if it exists (or |
| 2169 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell |
| 2170 | that runs an initialization file---such as @file{.cshrc} for C-shell, or |
| 2171 | @file{.bashrc} for BASH---any variables you set in that file affect |
| 2172 | your program. You may wish to move setting of environment variables to |
| 2173 | files that are only run when you sign on, such as @file{.login} or |
| 2174 | @file{.profile}. |
| 2175 | |
| 2176 | @node Working Directory |
| 2177 | @section Your Program's Working Directory |
| 2178 | |
| 2179 | @cindex working directory (of your program) |
| 2180 | Each time you start your program with @code{run}, it inherits its |
| 2181 | working directory from the current working directory of @value{GDBN}. |
| 2182 | The @value{GDBN} working directory is initially whatever it inherited |
| 2183 | from its parent process (typically the shell), but you can specify a new |
| 2184 | working directory in @value{GDBN} with the @code{cd} command. |
| 2185 | |
| 2186 | The @value{GDBN} working directory also serves as a default for the commands |
| 2187 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to |
| 2188 | Specify Files}. |
| 2189 | |
| 2190 | @table @code |
| 2191 | @kindex cd |
| 2192 | @cindex change working directory |
| 2193 | @item cd @var{directory} |
| 2194 | Set the @value{GDBN} working directory to @var{directory}. |
| 2195 | |
| 2196 | @kindex pwd |
| 2197 | @item pwd |
| 2198 | Print the @value{GDBN} working directory. |
| 2199 | @end table |
| 2200 | |
| 2201 | It is generally impossible to find the current working directory of |
| 2202 | the process being debugged (since a program can change its directory |
| 2203 | during its run). If you work on a system where @value{GDBN} is |
| 2204 | configured with the @file{/proc} support, you can use the @code{info |
| 2205 | proc} command (@pxref{SVR4 Process Information}) to find out the |
| 2206 | current working directory of the debuggee. |
| 2207 | |
| 2208 | @node Input/Output |
| 2209 | @section Your Program's Input and Output |
| 2210 | |
| 2211 | @cindex redirection |
| 2212 | @cindex i/o |
| 2213 | @cindex terminal |
| 2214 | By default, the program you run under @value{GDBN} does input and output to |
| 2215 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal |
| 2216 | to its own terminal modes to interact with you, but it records the terminal |
| 2217 | modes your program was using and switches back to them when you continue |
| 2218 | running your program. |
| 2219 | |
| 2220 | @table @code |
| 2221 | @kindex info terminal |
| 2222 | @item info terminal |
| 2223 | Displays information recorded by @value{GDBN} about the terminal modes your |
| 2224 | program is using. |
| 2225 | @end table |
| 2226 | |
| 2227 | You can redirect your program's input and/or output using shell |
| 2228 | redirection with the @code{run} command. For example, |
| 2229 | |
| 2230 | @smallexample |
| 2231 | run > outfile |
| 2232 | @end smallexample |
| 2233 | |
| 2234 | @noindent |
| 2235 | starts your program, diverting its output to the file @file{outfile}. |
| 2236 | |
| 2237 | @kindex tty |
| 2238 | @cindex controlling terminal |
| 2239 | Another way to specify where your program should do input and output is |
| 2240 | with the @code{tty} command. This command accepts a file name as |
| 2241 | argument, and causes this file to be the default for future @code{run} |
| 2242 | commands. It also resets the controlling terminal for the child |
| 2243 | process, for future @code{run} commands. For example, |
| 2244 | |
| 2245 | @smallexample |
| 2246 | tty /dev/ttyb |
| 2247 | @end smallexample |
| 2248 | |
| 2249 | @noindent |
| 2250 | directs that processes started with subsequent @code{run} commands |
| 2251 | default to do input and output on the terminal @file{/dev/ttyb} and have |
| 2252 | that as their controlling terminal. |
| 2253 | |
| 2254 | An explicit redirection in @code{run} overrides the @code{tty} command's |
| 2255 | effect on the input/output device, but not its effect on the controlling |
| 2256 | terminal. |
| 2257 | |
| 2258 | When you use the @code{tty} command or redirect input in the @code{run} |
| 2259 | command, only the input @emph{for your program} is affected. The input |
| 2260 | for @value{GDBN} still comes from your terminal. @code{tty} is an alias |
| 2261 | for @code{set inferior-tty}. |
| 2262 | |
| 2263 | @cindex inferior tty |
| 2264 | @cindex set inferior controlling terminal |
| 2265 | You can use the @code{show inferior-tty} command to tell @value{GDBN} to |
| 2266 | display the name of the terminal that will be used for future runs of your |
| 2267 | program. |
| 2268 | |
| 2269 | @table @code |
| 2270 | @item set inferior-tty /dev/ttyb |
| 2271 | @kindex set inferior-tty |
| 2272 | Set the tty for the program being debugged to /dev/ttyb. |
| 2273 | |
| 2274 | @item show inferior-tty |
| 2275 | @kindex show inferior-tty |
| 2276 | Show the current tty for the program being debugged. |
| 2277 | @end table |
| 2278 | |
| 2279 | @node Attach |
| 2280 | @section Debugging an Already-running Process |
| 2281 | @kindex attach |
| 2282 | @cindex attach |
| 2283 | |
| 2284 | @table @code |
| 2285 | @item attach @var{process-id} |
| 2286 | This command attaches to a running process---one that was started |
| 2287 | outside @value{GDBN}. (@code{info files} shows your active |
| 2288 | targets.) The command takes as argument a process ID. The usual way to |
| 2289 | find out the @var{process-id} of a Unix process is with the @code{ps} utility, |
| 2290 | or with the @samp{jobs -l} shell command. |
| 2291 | |
| 2292 | @code{attach} does not repeat if you press @key{RET} a second time after |
| 2293 | executing the command. |
| 2294 | @end table |
| 2295 | |
| 2296 | To use @code{attach}, your program must be running in an environment |
| 2297 | which supports processes; for example, @code{attach} does not work for |
| 2298 | programs on bare-board targets that lack an operating system. You must |
| 2299 | also have permission to send the process a signal. |
| 2300 | |
| 2301 | When you use @code{attach}, the debugger finds the program running in |
| 2302 | the process first by looking in the current working directory, then (if |
| 2303 | the program is not found) by using the source file search path |
| 2304 | (@pxref{Source Path, ,Specifying Source Directories}). You can also use |
| 2305 | the @code{file} command to load the program. @xref{Files, ,Commands to |
| 2306 | Specify Files}. |
| 2307 | |
| 2308 | The first thing @value{GDBN} does after arranging to debug the specified |
| 2309 | process is to stop it. You can examine and modify an attached process |
| 2310 | with all the @value{GDBN} commands that are ordinarily available when |
| 2311 | you start processes with @code{run}. You can insert breakpoints; you |
| 2312 | can step and continue; you can modify storage. If you would rather the |
| 2313 | process continue running, you may use the @code{continue} command after |
| 2314 | attaching @value{GDBN} to the process. |
| 2315 | |
| 2316 | @table @code |
| 2317 | @kindex detach |
| 2318 | @item detach |
| 2319 | When you have finished debugging the attached process, you can use the |
| 2320 | @code{detach} command to release it from @value{GDBN} control. Detaching |
| 2321 | the process continues its execution. After the @code{detach} command, |
| 2322 | that process and @value{GDBN} become completely independent once more, and you |
| 2323 | are ready to @code{attach} another process or start one with @code{run}. |
| 2324 | @code{detach} does not repeat if you press @key{RET} again after |
| 2325 | executing the command. |
| 2326 | @end table |
| 2327 | |
| 2328 | If you exit @value{GDBN} while you have an attached process, you detach |
| 2329 | that process. If you use the @code{run} command, you kill that process. |
| 2330 | By default, @value{GDBN} asks for confirmation if you try to do either of these |
| 2331 | things; you can control whether or not you need to confirm by using the |
| 2332 | @code{set confirm} command (@pxref{Messages/Warnings, ,Optional Warnings and |
| 2333 | Messages}). |
| 2334 | |
| 2335 | @node Kill Process |
| 2336 | @section Killing the Child Process |
| 2337 | |
| 2338 | @table @code |
| 2339 | @kindex kill |
| 2340 | @item kill |
| 2341 | Kill the child process in which your program is running under @value{GDBN}. |
| 2342 | @end table |
| 2343 | |
| 2344 | This command is useful if you wish to debug a core dump instead of a |
| 2345 | running process. @value{GDBN} ignores any core dump file while your program |
| 2346 | is running. |
| 2347 | |
| 2348 | On some operating systems, a program cannot be executed outside @value{GDBN} |
| 2349 | while you have breakpoints set on it inside @value{GDBN}. You can use the |
| 2350 | @code{kill} command in this situation to permit running your program |
| 2351 | outside the debugger. |
| 2352 | |
| 2353 | The @code{kill} command is also useful if you wish to recompile and |
| 2354 | relink your program, since on many systems it is impossible to modify an |
| 2355 | executable file while it is running in a process. In this case, when you |
| 2356 | next type @code{run}, @value{GDBN} notices that the file has changed, and |
| 2357 | reads the symbol table again (while trying to preserve your current |
| 2358 | breakpoint settings). |
| 2359 | |
| 2360 | @node Inferiors |
| 2361 | @section Debugging Multiple Inferiors |
| 2362 | |
| 2363 | Some @value{GDBN} targets are able to run multiple processes created |
| 2364 | from a single executable. This can happen, for instance, with an |
| 2365 | embedded system reporting back several processes via the remote |
| 2366 | protocol. |
| 2367 | |
| 2368 | @cindex inferior |
| 2369 | @value{GDBN} represents the state of each program execution with an |
| 2370 | object called an @dfn{inferior}. An inferior typically corresponds to |
| 2371 | a process, but is more general and applies also to targets that do not |
| 2372 | have processes. Inferiors may be created before a process runs, and |
| 2373 | may (in future) be retained after a process exits. Each run of an |
| 2374 | executable creates a new inferior, as does each attachment to an |
| 2375 | existing process. Inferiors have unique identifiers that are |
| 2376 | different from process ids, and may optionally be named as well. |
| 2377 | Usually each inferior will also have its own distinct address space, |
| 2378 | although some embedded targets may have several inferiors running in |
| 2379 | different parts of a single space. |
| 2380 | |
| 2381 | Each inferior may in turn have multiple threads running in it. |
| 2382 | |
| 2383 | To find out what inferiors exist at any moment, use @code{info inferiors}: |
| 2384 | |
| 2385 | @table @code |
| 2386 | @kindex info inferiors |
| 2387 | @item info inferiors |
| 2388 | Print a list of all inferiors currently being managed by @value{GDBN}. |
| 2389 | |
| 2390 | @kindex set print inferior-events |
| 2391 | @cindex print messages on inferior start and exit |
| 2392 | @item set print inferior-events |
| 2393 | @itemx set print inferior-events on |
| 2394 | @itemx set print inferior-events off |
| 2395 | The @code{set print inferior-events} command allows you to enable or |
| 2396 | disable printing of messages when @value{GDBN} notices that new |
| 2397 | inferiors have started or that inferiors have exited or have been |
| 2398 | detached. By default, these messages will not be printed. |
| 2399 | |
| 2400 | @kindex show print inferior-events |
| 2401 | @item show print inferior-events |
| 2402 | Show whether messages will be printed when @value{GDBN} detects that |
| 2403 | inferiors have started, exited or have been detached. |
| 2404 | @end table |
| 2405 | |
| 2406 | @node Threads |
| 2407 | @section Debugging Programs with Multiple Threads |
| 2408 | |
| 2409 | @cindex threads of execution |
| 2410 | @cindex multiple threads |
| 2411 | @cindex switching threads |
| 2412 | In some operating systems, such as HP-UX and Solaris, a single program |
| 2413 | may have more than one @dfn{thread} of execution. The precise semantics |
| 2414 | of threads differ from one operating system to another, but in general |
| 2415 | the threads of a single program are akin to multiple processes---except |
| 2416 | that they share one address space (that is, they can all examine and |
| 2417 | modify the same variables). On the other hand, each thread has its own |
| 2418 | registers and execution stack, and perhaps private memory. |
| 2419 | |
| 2420 | @value{GDBN} provides these facilities for debugging multi-thread |
| 2421 | programs: |
| 2422 | |
| 2423 | @itemize @bullet |
| 2424 | @item automatic notification of new threads |
| 2425 | @item @samp{thread @var{threadno}}, a command to switch among threads |
| 2426 | @item @samp{info threads}, a command to inquire about existing threads |
| 2427 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, |
| 2428 | a command to apply a command to a list of threads |
| 2429 | @item thread-specific breakpoints |
| 2430 | @item @samp{set print thread-events}, which controls printing of |
| 2431 | messages on thread start and exit. |
| 2432 | @end itemize |
| 2433 | |
| 2434 | @quotation |
| 2435 | @emph{Warning:} These facilities are not yet available on every |
| 2436 | @value{GDBN} configuration where the operating system supports threads. |
| 2437 | If your @value{GDBN} does not support threads, these commands have no |
| 2438 | effect. For example, a system without thread support shows no output |
| 2439 | from @samp{info threads}, and always rejects the @code{thread} command, |
| 2440 | like this: |
| 2441 | |
| 2442 | @smallexample |
| 2443 | (@value{GDBP}) info threads |
| 2444 | (@value{GDBP}) thread 1 |
| 2445 | Thread ID 1 not known. Use the "info threads" command to |
| 2446 | see the IDs of currently known threads. |
| 2447 | @end smallexample |
| 2448 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB |
| 2449 | @c doesn't support threads"? |
| 2450 | @end quotation |
| 2451 | |
| 2452 | @cindex focus of debugging |
| 2453 | @cindex current thread |
| 2454 | The @value{GDBN} thread debugging facility allows you to observe all |
| 2455 | threads while your program runs---but whenever @value{GDBN} takes |
| 2456 | control, one thread in particular is always the focus of debugging. |
| 2457 | This thread is called the @dfn{current thread}. Debugging commands show |
| 2458 | program information from the perspective of the current thread. |
| 2459 | |
| 2460 | @cindex @code{New} @var{systag} message |
| 2461 | @cindex thread identifier (system) |
| 2462 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
| 2463 | @c included GDB's numeric thread handle, so you could just go to that |
| 2464 | @c thread without first checking `info threads'. |
| 2465 | Whenever @value{GDBN} detects a new thread in your program, it displays |
| 2466 | the target system's identification for the thread with a message in the |
| 2467 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier |
| 2468 | whose form varies depending on the particular system. For example, on |
| 2469 | @sc{gnu}/Linux, you might see |
| 2470 | |
| 2471 | @smallexample |
| 2472 | [New Thread 46912507313328 (LWP 25582)] |
| 2473 | @end smallexample |
| 2474 | |
| 2475 | @noindent |
| 2476 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, |
| 2477 | the @var{systag} is simply something like @samp{process 368}, with no |
| 2478 | further qualifier. |
| 2479 | |
| 2480 | @c FIXME!! (1) Does the [New...] message appear even for the very first |
| 2481 | @c thread of a program, or does it only appear for the |
| 2482 | @c second---i.e.@: when it becomes obvious we have a multithread |
| 2483 | @c program? |
| 2484 | @c (2) *Is* there necessarily a first thread always? Or do some |
| 2485 | @c multithread systems permit starting a program with multiple |
| 2486 | @c threads ab initio? |
| 2487 | |
| 2488 | @cindex thread number |
| 2489 | @cindex thread identifier (GDB) |
| 2490 | For debugging purposes, @value{GDBN} associates its own thread |
| 2491 | number---always a single integer---with each thread in your program. |
| 2492 | |
| 2493 | @table @code |
| 2494 | @kindex info threads |
| 2495 | @item info threads |
| 2496 | Display a summary of all threads currently in your |
| 2497 | program. @value{GDBN} displays for each thread (in this order): |
| 2498 | |
| 2499 | @enumerate |
| 2500 | @item |
| 2501 | the thread number assigned by @value{GDBN} |
| 2502 | |
| 2503 | @item |
| 2504 | the target system's thread identifier (@var{systag}) |
| 2505 | |
| 2506 | @item |
| 2507 | the current stack frame summary for that thread |
| 2508 | @end enumerate |
| 2509 | |
| 2510 | @noindent |
| 2511 | An asterisk @samp{*} to the left of the @value{GDBN} thread number |
| 2512 | indicates the current thread. |
| 2513 | |
| 2514 | For example, |
| 2515 | @end table |
| 2516 | @c end table here to get a little more width for example |
| 2517 | |
| 2518 | @smallexample |
| 2519 | (@value{GDBP}) info threads |
| 2520 | 3 process 35 thread 27 0x34e5 in sigpause () |
| 2521 | 2 process 35 thread 23 0x34e5 in sigpause () |
| 2522 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) |
| 2523 | at threadtest.c:68 |
| 2524 | @end smallexample |
| 2525 | |
| 2526 | On HP-UX systems: |
| 2527 | |
| 2528 | @cindex debugging multithreaded programs (on HP-UX) |
| 2529 | @cindex thread identifier (GDB), on HP-UX |
| 2530 | For debugging purposes, @value{GDBN} associates its own thread |
| 2531 | number---a small integer assigned in thread-creation order---with each |
| 2532 | thread in your program. |
| 2533 | |
| 2534 | @cindex @code{New} @var{systag} message, on HP-UX |
| 2535 | @cindex thread identifier (system), on HP-UX |
| 2536 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
| 2537 | @c included GDB's numeric thread handle, so you could just go to that |
| 2538 | @c thread without first checking `info threads'. |
| 2539 | Whenever @value{GDBN} detects a new thread in your program, it displays |
| 2540 | both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the |
| 2541 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier |
| 2542 | whose form varies depending on the particular system. For example, on |
| 2543 | HP-UX, you see |
| 2544 | |
| 2545 | @smallexample |
| 2546 | [New thread 2 (system thread 26594)] |
| 2547 | @end smallexample |
| 2548 | |
| 2549 | @noindent |
| 2550 | when @value{GDBN} notices a new thread. |
| 2551 | |
| 2552 | @table @code |
| 2553 | @kindex info threads (HP-UX) |
| 2554 | @item info threads |
| 2555 | Display a summary of all threads currently in your |
| 2556 | program. @value{GDBN} displays for each thread (in this order): |
| 2557 | |
| 2558 | @enumerate |
| 2559 | @item the thread number assigned by @value{GDBN} |
| 2560 | |
| 2561 | @item the target system's thread identifier (@var{systag}) |
| 2562 | |
| 2563 | @item the current stack frame summary for that thread |
| 2564 | @end enumerate |
| 2565 | |
| 2566 | @noindent |
| 2567 | An asterisk @samp{*} to the left of the @value{GDBN} thread number |
| 2568 | indicates the current thread. |
| 2569 | |
| 2570 | For example, |
| 2571 | @end table |
| 2572 | @c end table here to get a little more width for example |
| 2573 | |
| 2574 | @smallexample |
| 2575 | (@value{GDBP}) info threads |
| 2576 | * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") \@* |
| 2577 | at quicksort.c:137 |
| 2578 | 2 system thread 26606 0x7b0030d8 in __ksleep () \@* |
| 2579 | from /usr/lib/libc.2 |
| 2580 | 1 system thread 27905 0x7b003498 in _brk () \@* |
| 2581 | from /usr/lib/libc.2 |
| 2582 | @end smallexample |
| 2583 | |
| 2584 | On Solaris, you can display more information about user threads with a |
| 2585 | Solaris-specific command: |
| 2586 | |
| 2587 | @table @code |
| 2588 | @item maint info sol-threads |
| 2589 | @kindex maint info sol-threads |
| 2590 | @cindex thread info (Solaris) |
| 2591 | Display info on Solaris user threads. |
| 2592 | @end table |
| 2593 | |
| 2594 | @table @code |
| 2595 | @kindex thread @var{threadno} |
| 2596 | @item thread @var{threadno} |
| 2597 | Make thread number @var{threadno} the current thread. The command |
| 2598 | argument @var{threadno} is the internal @value{GDBN} thread number, as |
| 2599 | shown in the first field of the @samp{info threads} display. |
| 2600 | @value{GDBN} responds by displaying the system identifier of the thread |
| 2601 | you selected, and its current stack frame summary: |
| 2602 | |
| 2603 | @smallexample |
| 2604 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one |
| 2605 | (@value{GDBP}) thread 2 |
| 2606 | [Switching to process 35 thread 23] |
| 2607 | 0x34e5 in sigpause () |
| 2608 | @end smallexample |
| 2609 | |
| 2610 | @noindent |
| 2611 | As with the @samp{[New @dots{}]} message, the form of the text after |
| 2612 | @samp{Switching to} depends on your system's conventions for identifying |
| 2613 | threads. |
| 2614 | |
| 2615 | @kindex thread apply |
| 2616 | @cindex apply command to several threads |
| 2617 | @item thread apply [@var{threadno}] [@var{all}] @var{command} |
| 2618 | The @code{thread apply} command allows you to apply the named |
| 2619 | @var{command} to one or more threads. Specify the numbers of the |
| 2620 | threads that you want affected with the command argument |
| 2621 | @var{threadno}. It can be a single thread number, one of the numbers |
| 2622 | shown in the first field of the @samp{info threads} display; or it |
| 2623 | could be a range of thread numbers, as in @code{2-4}. To apply a |
| 2624 | command to all threads, type @kbd{thread apply all @var{command}}. |
| 2625 | |
| 2626 | @kindex set print thread-events |
| 2627 | @cindex print messages on thread start and exit |
| 2628 | @item set print thread-events |
| 2629 | @itemx set print thread-events on |
| 2630 | @itemx set print thread-events off |
| 2631 | The @code{set print thread-events} command allows you to enable or |
| 2632 | disable printing of messages when @value{GDBN} notices that new threads have |
| 2633 | started or that threads have exited. By default, these messages will |
| 2634 | be printed if detection of these events is supported by the target. |
| 2635 | Note that these messages cannot be disabled on all targets. |
| 2636 | |
| 2637 | @kindex show print thread-events |
| 2638 | @item show print thread-events |
| 2639 | Show whether messages will be printed when @value{GDBN} detects that threads |
| 2640 | have started and exited. |
| 2641 | @end table |
| 2642 | |
| 2643 | @xref{Thread Stops,,Stopping and Starting Multi-thread Programs}, for |
| 2644 | more information about how @value{GDBN} behaves when you stop and start |
| 2645 | programs with multiple threads. |
| 2646 | |
| 2647 | @xref{Set Watchpoints,,Setting Watchpoints}, for information about |
| 2648 | watchpoints in programs with multiple threads. |
| 2649 | |
| 2650 | @node Processes |
| 2651 | @section Debugging Programs with Multiple Processes |
| 2652 | |
| 2653 | @cindex fork, debugging programs which call |
| 2654 | @cindex multiple processes |
| 2655 | @cindex processes, multiple |
| 2656 | On most systems, @value{GDBN} has no special support for debugging |
| 2657 | programs which create additional processes using the @code{fork} |
| 2658 | function. When a program forks, @value{GDBN} will continue to debug the |
| 2659 | parent process and the child process will run unimpeded. If you have |
| 2660 | set a breakpoint in any code which the child then executes, the child |
| 2661 | will get a @code{SIGTRAP} signal which (unless it catches the signal) |
| 2662 | will cause it to terminate. |
| 2663 | |
| 2664 | However, if you want to debug the child process there is a workaround |
| 2665 | which isn't too painful. Put a call to @code{sleep} in the code which |
| 2666 | the child process executes after the fork. It may be useful to sleep |
| 2667 | only if a certain environment variable is set, or a certain file exists, |
| 2668 | so that the delay need not occur when you don't want to run @value{GDBN} |
| 2669 | on the child. While the child is sleeping, use the @code{ps} program to |
| 2670 | get its process ID. Then tell @value{GDBN} (a new invocation of |
| 2671 | @value{GDBN} if you are also debugging the parent process) to attach to |
| 2672 | the child process (@pxref{Attach}). From that point on you can debug |
| 2673 | the child process just like any other process which you attached to. |
| 2674 | |
| 2675 | On some systems, @value{GDBN} provides support for debugging programs that |
| 2676 | create additional processes using the @code{fork} or @code{vfork} functions. |
| 2677 | Currently, the only platforms with this feature are HP-UX (11.x and later |
| 2678 | only?) and @sc{gnu}/Linux (kernel version 2.5.60 and later). |
| 2679 | |
| 2680 | By default, when a program forks, @value{GDBN} will continue to debug |
| 2681 | the parent process and the child process will run unimpeded. |
| 2682 | |
| 2683 | If you want to follow the child process instead of the parent process, |
| 2684 | use the command @w{@code{set follow-fork-mode}}. |
| 2685 | |
| 2686 | @table @code |
| 2687 | @kindex set follow-fork-mode |
| 2688 | @item set follow-fork-mode @var{mode} |
| 2689 | Set the debugger response to a program call of @code{fork} or |
| 2690 | @code{vfork}. A call to @code{fork} or @code{vfork} creates a new |
| 2691 | process. The @var{mode} argument can be: |
| 2692 | |
| 2693 | @table @code |
| 2694 | @item parent |
| 2695 | The original process is debugged after a fork. The child process runs |
| 2696 | unimpeded. This is the default. |
| 2697 | |
| 2698 | @item child |
| 2699 | The new process is debugged after a fork. The parent process runs |
| 2700 | unimpeded. |
| 2701 | |
| 2702 | @end table |
| 2703 | |
| 2704 | @kindex show follow-fork-mode |
| 2705 | @item show follow-fork-mode |
| 2706 | Display the current debugger response to a @code{fork} or @code{vfork} call. |
| 2707 | @end table |
| 2708 | |
| 2709 | @cindex debugging multiple processes |
| 2710 | On Linux, if you want to debug both the parent and child processes, use the |
| 2711 | command @w{@code{set detach-on-fork}}. |
| 2712 | |
| 2713 | @table @code |
| 2714 | @kindex set detach-on-fork |
| 2715 | @item set detach-on-fork @var{mode} |
| 2716 | Tells gdb whether to detach one of the processes after a fork, or |
| 2717 | retain debugger control over them both. |
| 2718 | |
| 2719 | @table @code |
| 2720 | @item on |
| 2721 | The child process (or parent process, depending on the value of |
| 2722 | @code{follow-fork-mode}) will be detached and allowed to run |
| 2723 | independently. This is the default. |
| 2724 | |
| 2725 | @item off |
| 2726 | Both processes will be held under the control of @value{GDBN}. |
| 2727 | One process (child or parent, depending on the value of |
| 2728 | @code{follow-fork-mode}) is debugged as usual, while the other |
| 2729 | is held suspended. |
| 2730 | |
| 2731 | @end table |
| 2732 | |
| 2733 | @kindex show detach-on-fork |
| 2734 | @item show detach-on-fork |
| 2735 | Show whether detach-on-fork mode is on/off. |
| 2736 | @end table |
| 2737 | |
| 2738 | If you choose to set @samp{detach-on-fork} mode off, then |
| 2739 | @value{GDBN} will retain control of all forked processes (including |
| 2740 | nested forks). You can list the forked processes under the control of |
| 2741 | @value{GDBN} by using the @w{@code{info forks}} command, and switch |
| 2742 | from one fork to another by using the @w{@code{fork}} command. |
| 2743 | |
| 2744 | @table @code |
| 2745 | @kindex info forks |
| 2746 | @item info forks |
| 2747 | Print a list of all forked processes under the control of @value{GDBN}. |
| 2748 | The listing will include a fork id, a process id, and the current |
| 2749 | position (program counter) of the process. |
| 2750 | |
| 2751 | @kindex fork @var{fork-id} |
| 2752 | @item fork @var{fork-id} |
| 2753 | Make fork number @var{fork-id} the current process. The argument |
| 2754 | @var{fork-id} is the internal fork number assigned by @value{GDBN}, |
| 2755 | as shown in the first field of the @samp{info forks} display. |
| 2756 | |
| 2757 | @kindex process @var{process-id} |
| 2758 | @item process @var{process-id} |
| 2759 | Make process number @var{process-id} the current process. The |
| 2760 | argument @var{process-id} must be one that is listed in the output of |
| 2761 | @samp{info forks}. |
| 2762 | |
| 2763 | @end table |
| 2764 | |
| 2765 | To quit debugging one of the forked processes, you can either detach |
| 2766 | from it by using the @w{@code{detach fork}} command (allowing it to |
| 2767 | run independently), or delete (and kill) it using the |
| 2768 | @w{@code{delete fork}} command. |
| 2769 | |
| 2770 | @table @code |
| 2771 | @kindex detach fork @var{fork-id} |
| 2772 | @item detach fork @var{fork-id} |
| 2773 | Detach from the process identified by @value{GDBN} fork number |
| 2774 | @var{fork-id}, and remove it from the fork list. The process will be |
| 2775 | allowed to run independently. |
| 2776 | |
| 2777 | @kindex delete fork @var{fork-id} |
| 2778 | @item delete fork @var{fork-id} |
| 2779 | Kill the process identified by @value{GDBN} fork number @var{fork-id}, |
| 2780 | and remove it from the fork list. |
| 2781 | |
| 2782 | @end table |
| 2783 | |
| 2784 | If you ask to debug a child process and a @code{vfork} is followed by an |
| 2785 | @code{exec}, @value{GDBN} executes the new target up to the first |
| 2786 | breakpoint in the new target. If you have a breakpoint set on |
| 2787 | @code{main} in your original program, the breakpoint will also be set on |
| 2788 | the child process's @code{main}. |
| 2789 | |
| 2790 | When a child process is spawned by @code{vfork}, you cannot debug the |
| 2791 | child or parent until an @code{exec} call completes. |
| 2792 | |
| 2793 | If you issue a @code{run} command to @value{GDBN} after an @code{exec} |
| 2794 | call executes, the new target restarts. To restart the parent process, |
| 2795 | use the @code{file} command with the parent executable name as its |
| 2796 | argument. |
| 2797 | |
| 2798 | You can use the @code{catch} command to make @value{GDBN} stop whenever |
| 2799 | a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set |
| 2800 | Catchpoints, ,Setting Catchpoints}. |
| 2801 | |
| 2802 | @node Checkpoint/Restart |
| 2803 | @section Setting a @emph{Bookmark} to Return to Later |
| 2804 | |
| 2805 | @cindex checkpoint |
| 2806 | @cindex restart |
| 2807 | @cindex bookmark |
| 2808 | @cindex snapshot of a process |
| 2809 | @cindex rewind program state |
| 2810 | |
| 2811 | On certain operating systems@footnote{Currently, only |
| 2812 | @sc{gnu}/Linux.}, @value{GDBN} is able to save a @dfn{snapshot} of a |
| 2813 | program's state, called a @dfn{checkpoint}, and come back to it |
| 2814 | later. |
| 2815 | |
| 2816 | Returning to a checkpoint effectively undoes everything that has |
| 2817 | happened in the program since the @code{checkpoint} was saved. This |
| 2818 | includes changes in memory, registers, and even (within some limits) |
| 2819 | system state. Effectively, it is like going back in time to the |
| 2820 | moment when the checkpoint was saved. |
| 2821 | |
| 2822 | Thus, if you're stepping thru a program and you think you're |
| 2823 | getting close to the point where things go wrong, you can save |
| 2824 | a checkpoint. Then, if you accidentally go too far and miss |
| 2825 | the critical statement, instead of having to restart your program |
| 2826 | from the beginning, you can just go back to the checkpoint and |
| 2827 | start again from there. |
| 2828 | |
| 2829 | This can be especially useful if it takes a lot of time or |
| 2830 | steps to reach the point where you think the bug occurs. |
| 2831 | |
| 2832 | To use the @code{checkpoint}/@code{restart} method of debugging: |
| 2833 | |
| 2834 | @table @code |
| 2835 | @kindex checkpoint |
| 2836 | @item checkpoint |
| 2837 | Save a snapshot of the debugged program's current execution state. |
| 2838 | The @code{checkpoint} command takes no arguments, but each checkpoint |
| 2839 | is assigned a small integer id, similar to a breakpoint id. |
| 2840 | |
| 2841 | @kindex info checkpoints |
| 2842 | @item info checkpoints |
| 2843 | List the checkpoints that have been saved in the current debugging |
| 2844 | session. For each checkpoint, the following information will be |
| 2845 | listed: |
| 2846 | |
| 2847 | @table @code |
| 2848 | @item Checkpoint ID |
| 2849 | @item Process ID |
| 2850 | @item Code Address |
| 2851 | @item Source line, or label |
| 2852 | @end table |
| 2853 | |
| 2854 | @kindex restart @var{checkpoint-id} |
| 2855 | @item restart @var{checkpoint-id} |
| 2856 | Restore the program state that was saved as checkpoint number |
| 2857 | @var{checkpoint-id}. All program variables, registers, stack frames |
| 2858 | etc.@: will be returned to the values that they had when the checkpoint |
| 2859 | was saved. In essence, gdb will ``wind back the clock'' to the point |
| 2860 | in time when the checkpoint was saved. |
| 2861 | |
| 2862 | Note that breakpoints, @value{GDBN} variables, command history etc. |
| 2863 | are not affected by restoring a checkpoint. In general, a checkpoint |
| 2864 | only restores things that reside in the program being debugged, not in |
| 2865 | the debugger. |
| 2866 | |
| 2867 | @kindex delete checkpoint @var{checkpoint-id} |
| 2868 | @item delete checkpoint @var{checkpoint-id} |
| 2869 | Delete the previously-saved checkpoint identified by @var{checkpoint-id}. |
| 2870 | |
| 2871 | @end table |
| 2872 | |
| 2873 | Returning to a previously saved checkpoint will restore the user state |
| 2874 | of the program being debugged, plus a significant subset of the system |
| 2875 | (OS) state, including file pointers. It won't ``un-write'' data from |
| 2876 | a file, but it will rewind the file pointer to the previous location, |
| 2877 | so that the previously written data can be overwritten. For files |
| 2878 | opened in read mode, the pointer will also be restored so that the |
| 2879 | previously read data can be read again. |
| 2880 | |
| 2881 | Of course, characters that have been sent to a printer (or other |
| 2882 | external device) cannot be ``snatched back'', and characters received |
| 2883 | from eg.@: a serial device can be removed from internal program buffers, |
| 2884 | but they cannot be ``pushed back'' into the serial pipeline, ready to |
| 2885 | be received again. Similarly, the actual contents of files that have |
| 2886 | been changed cannot be restored (at this time). |
| 2887 | |
| 2888 | However, within those constraints, you actually can ``rewind'' your |
| 2889 | program to a previously saved point in time, and begin debugging it |
| 2890 | again --- and you can change the course of events so as to debug a |
| 2891 | different execution path this time. |
| 2892 | |
| 2893 | @cindex checkpoints and process id |
| 2894 | Finally, there is one bit of internal program state that will be |
| 2895 | different when you return to a checkpoint --- the program's process |
| 2896 | id. Each checkpoint will have a unique process id (or @var{pid}), |
| 2897 | and each will be different from the program's original @var{pid}. |
| 2898 | If your program has saved a local copy of its process id, this could |
| 2899 | potentially pose a problem. |
| 2900 | |
| 2901 | @subsection A Non-obvious Benefit of Using Checkpoints |
| 2902 | |
| 2903 | On some systems such as @sc{gnu}/Linux, address space randomization |
| 2904 | is performed on new processes for security reasons. This makes it |
| 2905 | difficult or impossible to set a breakpoint, or watchpoint, on an |
| 2906 | absolute address if you have to restart the program, since the |
| 2907 | absolute location of a symbol will change from one execution to the |
| 2908 | next. |
| 2909 | |
| 2910 | A checkpoint, however, is an @emph{identical} copy of a process. |
| 2911 | Therefore if you create a checkpoint at (eg.@:) the start of main, |
| 2912 | and simply return to that checkpoint instead of restarting the |
| 2913 | process, you can avoid the effects of address randomization and |
| 2914 | your symbols will all stay in the same place. |
| 2915 | |
| 2916 | @node Stopping |
| 2917 | @chapter Stopping and Continuing |
| 2918 | |
| 2919 | The principal purposes of using a debugger are so that you can stop your |
| 2920 | program before it terminates; or so that, if your program runs into |
| 2921 | trouble, you can investigate and find out why. |
| 2922 | |
| 2923 | Inside @value{GDBN}, your program may stop for any of several reasons, |
| 2924 | such as a signal, a breakpoint, or reaching a new line after a |
| 2925 | @value{GDBN} command such as @code{step}. You may then examine and |
| 2926 | change variables, set new breakpoints or remove old ones, and then |
| 2927 | continue execution. Usually, the messages shown by @value{GDBN} provide |
| 2928 | ample explanation of the status of your program---but you can also |
| 2929 | explicitly request this information at any time. |
| 2930 | |
| 2931 | @table @code |
| 2932 | @kindex info program |
| 2933 | @item info program |
| 2934 | Display information about the status of your program: whether it is |
| 2935 | running or not, what process it is, and why it stopped. |
| 2936 | @end table |
| 2937 | |
| 2938 | @menu |
| 2939 | * Breakpoints:: Breakpoints, watchpoints, and catchpoints |
| 2940 | * Continuing and Stepping:: Resuming execution |
| 2941 | * Signals:: Signals |
| 2942 | * Thread Stops:: Stopping and starting multi-thread programs |
| 2943 | @end menu |
| 2944 | |
| 2945 | @node Breakpoints |
| 2946 | @section Breakpoints, Watchpoints, and Catchpoints |
| 2947 | |
| 2948 | @cindex breakpoints |
| 2949 | A @dfn{breakpoint} makes your program stop whenever a certain point in |
| 2950 | the program is reached. For each breakpoint, you can add conditions to |
| 2951 | control in finer detail whether your program stops. You can set |
| 2952 | breakpoints with the @code{break} command and its variants (@pxref{Set |
| 2953 | Breaks, ,Setting Breakpoints}), to specify the place where your program |
| 2954 | should stop by line number, function name or exact address in the |
| 2955 | program. |
| 2956 | |
| 2957 | On some systems, you can set breakpoints in shared libraries before |
| 2958 | the executable is run. There is a minor limitation on HP-UX systems: |
| 2959 | you must wait until the executable is run in order to set breakpoints |
| 2960 | in shared library routines that are not called directly by the program |
| 2961 | (for example, routines that are arguments in a @code{pthread_create} |
| 2962 | call). |
| 2963 | |
| 2964 | @cindex watchpoints |
| 2965 | @cindex data breakpoints |
| 2966 | @cindex memory tracing |
| 2967 | @cindex breakpoint on memory address |
| 2968 | @cindex breakpoint on variable modification |
| 2969 | A @dfn{watchpoint} is a special breakpoint that stops your program |
| 2970 | when the value of an expression changes. The expression may be a value |
| 2971 | of a variable, or it could involve values of one or more variables |
| 2972 | combined by operators, such as @samp{a + b}. This is sometimes called |
| 2973 | @dfn{data breakpoints}. You must use a different command to set |
| 2974 | watchpoints (@pxref{Set Watchpoints, ,Setting Watchpoints}), but aside |
| 2975 | from that, you can manage a watchpoint like any other breakpoint: you |
| 2976 | enable, disable, and delete both breakpoints and watchpoints using the |
| 2977 | same commands. |
| 2978 | |
| 2979 | You can arrange to have values from your program displayed automatically |
| 2980 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, |
| 2981 | Automatic Display}. |
| 2982 | |
| 2983 | @cindex catchpoints |
| 2984 | @cindex breakpoint on events |
| 2985 | A @dfn{catchpoint} is another special breakpoint that stops your program |
| 2986 | when a certain kind of event occurs, such as the throwing of a C@t{++} |
| 2987 | exception or the loading of a library. As with watchpoints, you use a |
| 2988 | different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting |
| 2989 | Catchpoints}), but aside from that, you can manage a catchpoint like any |
| 2990 | other breakpoint. (To stop when your program receives a signal, use the |
| 2991 | @code{handle} command; see @ref{Signals, ,Signals}.) |
| 2992 | |
| 2993 | @cindex breakpoint numbers |
| 2994 | @cindex numbers for breakpoints |
| 2995 | @value{GDBN} assigns a number to each breakpoint, watchpoint, or |
| 2996 | catchpoint when you create it; these numbers are successive integers |
| 2997 | starting with one. In many of the commands for controlling various |
| 2998 | features of breakpoints you use the breakpoint number to say which |
| 2999 | breakpoint you want to change. Each breakpoint may be @dfn{enabled} or |
| 3000 | @dfn{disabled}; if disabled, it has no effect on your program until you |
| 3001 | enable it again. |
| 3002 | |
| 3003 | @cindex breakpoint ranges |
| 3004 | @cindex ranges of breakpoints |
| 3005 | Some @value{GDBN} commands accept a range of breakpoints on which to |
| 3006 | operate. A breakpoint range is either a single breakpoint number, like |
| 3007 | @samp{5}, or two such numbers, in increasing order, separated by a |
| 3008 | hyphen, like @samp{5-7}. When a breakpoint range is given to a command, |
| 3009 | all breakpoints in that range are operated on. |
| 3010 | |
| 3011 | @menu |
| 3012 | * Set Breaks:: Setting breakpoints |
| 3013 | * Set Watchpoints:: Setting watchpoints |
| 3014 | * Set Catchpoints:: Setting catchpoints |
| 3015 | * Delete Breaks:: Deleting breakpoints |
| 3016 | * Disabling:: Disabling breakpoints |
| 3017 | * Conditions:: Break conditions |
| 3018 | * Break Commands:: Breakpoint command lists |
| 3019 | * Error in Breakpoints:: ``Cannot insert breakpoints'' |
| 3020 | * Breakpoint-related Warnings:: ``Breakpoint address adjusted...'' |
| 3021 | @end menu |
| 3022 | |
| 3023 | @node Set Breaks |
| 3024 | @subsection Setting Breakpoints |
| 3025 | |
| 3026 | @c FIXME LMB what does GDB do if no code on line of breakpt? |
| 3027 | @c consider in particular declaration with/without initialization. |
| 3028 | @c |
| 3029 | @c FIXME 2 is there stuff on this already? break at fun start, already init? |
| 3030 | |
| 3031 | @kindex break |
| 3032 | @kindex b @r{(@code{break})} |
| 3033 | @vindex $bpnum@r{, convenience variable} |
| 3034 | @cindex latest breakpoint |
| 3035 | Breakpoints are set with the @code{break} command (abbreviated |
| 3036 | @code{b}). The debugger convenience variable @samp{$bpnum} records the |
| 3037 | number of the breakpoint you've set most recently; see @ref{Convenience |
| 3038 | Vars,, Convenience Variables}, for a discussion of what you can do with |
| 3039 | convenience variables. |
| 3040 | |
| 3041 | @table @code |
| 3042 | @item break @var{location} |
| 3043 | Set a breakpoint at the given @var{location}, which can specify a |
| 3044 | function name, a line number, or an address of an instruction. |
| 3045 | (@xref{Specify Location}, for a list of all the possible ways to |
| 3046 | specify a @var{location}.) The breakpoint will stop your program just |
| 3047 | before it executes any of the code in the specified @var{location}. |
| 3048 | |
| 3049 | When using source languages that permit overloading of symbols, such as |
| 3050 | C@t{++}, a function name may refer to more than one possible place to break. |
| 3051 | @xref{Ambiguous Expressions,,Ambiguous Expressions}, for a discussion of |
| 3052 | that situation. |
| 3053 | |
| 3054 | @item break |
| 3055 | When called without any arguments, @code{break} sets a breakpoint at |
| 3056 | the next instruction to be executed in the selected stack frame |
| 3057 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the |
| 3058 | innermost, this makes your program stop as soon as control |
| 3059 | returns to that frame. This is similar to the effect of a |
| 3060 | @code{finish} command in the frame inside the selected frame---except |
| 3061 | that @code{finish} does not leave an active breakpoint. If you use |
| 3062 | @code{break} without an argument in the innermost frame, @value{GDBN} stops |
| 3063 | the next time it reaches the current location; this may be useful |
| 3064 | inside loops. |
| 3065 | |
| 3066 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at |
| 3067 | least one instruction has been executed. If it did not do this, you |
| 3068 | would be unable to proceed past a breakpoint without first disabling the |
| 3069 | breakpoint. This rule applies whether or not the breakpoint already |
| 3070 | existed when your program stopped. |
| 3071 | |
| 3072 | @item break @dots{} if @var{cond} |
| 3073 | Set a breakpoint with condition @var{cond}; evaluate the expression |
| 3074 | @var{cond} each time the breakpoint is reached, and stop only if the |
| 3075 | value is nonzero---that is, if @var{cond} evaluates as true. |
| 3076 | @samp{@dots{}} stands for one of the possible arguments described |
| 3077 | above (or no argument) specifying where to break. @xref{Conditions, |
| 3078 | ,Break Conditions}, for more information on breakpoint conditions. |
| 3079 | |
| 3080 | @kindex tbreak |
| 3081 | @item tbreak @var{args} |
| 3082 | Set a breakpoint enabled only for one stop. @var{args} are the |
| 3083 | same as for the @code{break} command, and the breakpoint is set in the same |
| 3084 | way, but the breakpoint is automatically deleted after the first time your |
| 3085 | program stops there. @xref{Disabling, ,Disabling Breakpoints}. |
| 3086 | |
| 3087 | @kindex hbreak |
| 3088 | @cindex hardware breakpoints |
| 3089 | @item hbreak @var{args} |
| 3090 | Set a hardware-assisted breakpoint. @var{args} are the same as for the |
| 3091 | @code{break} command and the breakpoint is set in the same way, but the |
| 3092 | breakpoint requires hardware support and some target hardware may not |
| 3093 | have this support. The main purpose of this is EPROM/ROM code |
| 3094 | debugging, so you can set a breakpoint at an instruction without |
| 3095 | changing the instruction. This can be used with the new trap-generation |
| 3096 | provided by SPARClite DSU and most x86-based targets. These targets |
| 3097 | will generate traps when a program accesses some data or instruction |
| 3098 | address that is assigned to the debug registers. However the hardware |
| 3099 | breakpoint registers can take a limited number of breakpoints. For |
| 3100 | example, on the DSU, only two data breakpoints can be set at a time, and |
| 3101 | @value{GDBN} will reject this command if more than two are used. Delete |
| 3102 | or disable unused hardware breakpoints before setting new ones |
| 3103 | (@pxref{Disabling, ,Disabling Breakpoints}). |
| 3104 | @xref{Conditions, ,Break Conditions}. |
| 3105 | For remote targets, you can restrict the number of hardware |
| 3106 | breakpoints @value{GDBN} will use, see @ref{set remote |
| 3107 | hardware-breakpoint-limit}. |
| 3108 | |
| 3109 | @kindex thbreak |
| 3110 | @item thbreak @var{args} |
| 3111 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} |
| 3112 | are the same as for the @code{hbreak} command and the breakpoint is set in |
| 3113 | the same way. However, like the @code{tbreak} command, |
| 3114 | the breakpoint is automatically deleted after the |
| 3115 | first time your program stops there. Also, like the @code{hbreak} |
| 3116 | command, the breakpoint requires hardware support and some target hardware |
| 3117 | may not have this support. @xref{Disabling, ,Disabling Breakpoints}. |
| 3118 | See also @ref{Conditions, ,Break Conditions}. |
| 3119 | |
| 3120 | @kindex rbreak |
| 3121 | @cindex regular expression |
| 3122 | @cindex breakpoints in functions matching a regexp |
| 3123 | @cindex set breakpoints in many functions |
| 3124 | @item rbreak @var{regex} |
| 3125 | Set breakpoints on all functions matching the regular expression |
| 3126 | @var{regex}. This command sets an unconditional breakpoint on all |
| 3127 | matches, printing a list of all breakpoints it set. Once these |
| 3128 | breakpoints are set, they are treated just like the breakpoints set with |
| 3129 | the @code{break} command. You can delete them, disable them, or make |
| 3130 | them conditional the same way as any other breakpoint. |
| 3131 | |
| 3132 | The syntax of the regular expression is the standard one used with tools |
| 3133 | like @file{grep}. Note that this is different from the syntax used by |
| 3134 | shells, so for instance @code{foo*} matches all functions that include |
| 3135 | an @code{fo} followed by zero or more @code{o}s. There is an implicit |
| 3136 | @code{.*} leading and trailing the regular expression you supply, so to |
| 3137 | match only functions that begin with @code{foo}, use @code{^foo}. |
| 3138 | |
| 3139 | @cindex non-member C@t{++} functions, set breakpoint in |
| 3140 | When debugging C@t{++} programs, @code{rbreak} is useful for setting |
| 3141 | breakpoints on overloaded functions that are not members of any special |
| 3142 | classes. |
| 3143 | |
| 3144 | @cindex set breakpoints on all functions |
| 3145 | The @code{rbreak} command can be used to set breakpoints in |
| 3146 | @strong{all} the functions in a program, like this: |
| 3147 | |
| 3148 | @smallexample |
| 3149 | (@value{GDBP}) rbreak . |
| 3150 | @end smallexample |
| 3151 | |
| 3152 | @kindex info breakpoints |
| 3153 | @cindex @code{$_} and @code{info breakpoints} |
| 3154 | @item info breakpoints @r{[}@var{n}@r{]} |
| 3155 | @itemx info break @r{[}@var{n}@r{]} |
| 3156 | @itemx info watchpoints @r{[}@var{n}@r{]} |
| 3157 | Print a table of all breakpoints, watchpoints, and catchpoints set and |
| 3158 | not deleted. Optional argument @var{n} means print information only |
| 3159 | about the specified breakpoint (or watchpoint or catchpoint). For |
| 3160 | each breakpoint, following columns are printed: |
| 3161 | |
| 3162 | @table @emph |
| 3163 | @item Breakpoint Numbers |
| 3164 | @item Type |
| 3165 | Breakpoint, watchpoint, or catchpoint. |
| 3166 | @item Disposition |
| 3167 | Whether the breakpoint is marked to be disabled or deleted when hit. |
| 3168 | @item Enabled or Disabled |
| 3169 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints |
| 3170 | that are not enabled. |
| 3171 | @item Address |
| 3172 | Where the breakpoint is in your program, as a memory address. For a |
| 3173 | pending breakpoint whose address is not yet known, this field will |
| 3174 | contain @samp{<PENDING>}. Such breakpoint won't fire until a shared |
| 3175 | library that has the symbol or line referred by breakpoint is loaded. |
| 3176 | See below for details. A breakpoint with several locations will |
| 3177 | have @samp{<MULTIPLE>} in this field---see below for details. |
| 3178 | @item What |
| 3179 | Where the breakpoint is in the source for your program, as a file and |
| 3180 | line number. For a pending breakpoint, the original string passed to |
| 3181 | the breakpoint command will be listed as it cannot be resolved until |
| 3182 | the appropriate shared library is loaded in the future. |
| 3183 | @end table |
| 3184 | |
| 3185 | @noindent |
| 3186 | If a breakpoint is conditional, @code{info break} shows the condition on |
| 3187 | the line following the affected breakpoint; breakpoint commands, if any, |
| 3188 | are listed after that. A pending breakpoint is allowed to have a condition |
| 3189 | specified for it. The condition is not parsed for validity until a shared |
| 3190 | library is loaded that allows the pending breakpoint to resolve to a |
| 3191 | valid location. |
| 3192 | |
| 3193 | @noindent |
| 3194 | @code{info break} with a breakpoint |
| 3195 | number @var{n} as argument lists only that breakpoint. The |
| 3196 | convenience variable @code{$_} and the default examining-address for |
| 3197 | the @code{x} command are set to the address of the last breakpoint |
| 3198 | listed (@pxref{Memory, ,Examining Memory}). |
| 3199 | |
| 3200 | @noindent |
| 3201 | @code{info break} displays a count of the number of times the breakpoint |
| 3202 | has been hit. This is especially useful in conjunction with the |
| 3203 | @code{ignore} command. You can ignore a large number of breakpoint |
| 3204 | hits, look at the breakpoint info to see how many times the breakpoint |
| 3205 | was hit, and then run again, ignoring one less than that number. This |
| 3206 | will get you quickly to the last hit of that breakpoint. |
| 3207 | @end table |
| 3208 | |
| 3209 | @value{GDBN} allows you to set any number of breakpoints at the same place in |
| 3210 | your program. There is nothing silly or meaningless about this. When |
| 3211 | the breakpoints are conditional, this is even useful |
| 3212 | (@pxref{Conditions, ,Break Conditions}). |
| 3213 | |
| 3214 | @cindex multiple locations, breakpoints |
| 3215 | @cindex breakpoints, multiple locations |
| 3216 | It is possible that a breakpoint corresponds to several locations |
| 3217 | in your program. Examples of this situation are: |
| 3218 | |
| 3219 | @itemize @bullet |
| 3220 | @item |
| 3221 | For a C@t{++} constructor, the @value{NGCC} compiler generates several |
| 3222 | instances of the function body, used in different cases. |
| 3223 | |
| 3224 | @item |
| 3225 | For a C@t{++} template function, a given line in the function can |
| 3226 | correspond to any number of instantiations. |
| 3227 | |
| 3228 | @item |
| 3229 | For an inlined function, a given source line can correspond to |
| 3230 | several places where that function is inlined. |
| 3231 | @end itemize |
| 3232 | |
| 3233 | In all those cases, @value{GDBN} will insert a breakpoint at all |
| 3234 | the relevant locations@footnote{ |
| 3235 | As of this writing, multiple-location breakpoints work only if there's |
| 3236 | line number information for all the locations. This means that they |
| 3237 | will generally not work in system libraries, unless you have debug |
| 3238 | info with line numbers for them.}. |
| 3239 | |
| 3240 | A breakpoint with multiple locations is displayed in the breakpoint |
| 3241 | table using several rows---one header row, followed by one row for |
| 3242 | each breakpoint location. The header row has @samp{<MULTIPLE>} in the |
| 3243 | address column. The rows for individual locations contain the actual |
| 3244 | addresses for locations, and show the functions to which those |
| 3245 | locations belong. The number column for a location is of the form |
| 3246 | @var{breakpoint-number}.@var{location-number}. |
| 3247 | |
| 3248 | For example: |
| 3249 | |
| 3250 | @smallexample |
| 3251 | Num Type Disp Enb Address What |
| 3252 | 1 breakpoint keep y <MULTIPLE> |
| 3253 | stop only if i==1 |
| 3254 | breakpoint already hit 1 time |
| 3255 | 1.1 y 0x080486a2 in void foo<int>() at t.cc:8 |
| 3256 | 1.2 y 0x080486ca in void foo<double>() at t.cc:8 |
| 3257 | @end smallexample |
| 3258 | |
| 3259 | Each location can be individually enabled or disabled by passing |
| 3260 | @var{breakpoint-number}.@var{location-number} as argument to the |
| 3261 | @code{enable} and @code{disable} commands. Note that you cannot |
| 3262 | delete the individual locations from the list, you can only delete the |
| 3263 | entire list of locations that belong to their parent breakpoint (with |
| 3264 | the @kbd{delete @var{num}} command, where @var{num} is the number of |
| 3265 | the parent breakpoint, 1 in the above example). Disabling or enabling |
| 3266 | the parent breakpoint (@pxref{Disabling}) affects all of the locations |
| 3267 | that belong to that breakpoint. |
| 3268 | |
| 3269 | @cindex pending breakpoints |
| 3270 | It's quite common to have a breakpoint inside a shared library. |
| 3271 | Shared libraries can be loaded and unloaded explicitly, |
| 3272 | and possibly repeatedly, as the program is executed. To support |
| 3273 | this use case, @value{GDBN} updates breakpoint locations whenever |
| 3274 | any shared library is loaded or unloaded. Typically, you would |
| 3275 | set a breakpoint in a shared library at the beginning of your |
| 3276 | debugging session, when the library is not loaded, and when the |
| 3277 | symbols from the library are not available. When you try to set |
| 3278 | breakpoint, @value{GDBN} will ask you if you want to set |
| 3279 | a so called @dfn{pending breakpoint}---breakpoint whose address |
| 3280 | is not yet resolved. |
| 3281 | |
| 3282 | After the program is run, whenever a new shared library is loaded, |
| 3283 | @value{GDBN} reevaluates all the breakpoints. When a newly loaded |
| 3284 | shared library contains the symbol or line referred to by some |
| 3285 | pending breakpoint, that breakpoint is resolved and becomes an |
| 3286 | ordinary breakpoint. When a library is unloaded, all breakpoints |
| 3287 | that refer to its symbols or source lines become pending again. |
| 3288 | |
| 3289 | This logic works for breakpoints with multiple locations, too. For |
| 3290 | example, if you have a breakpoint in a C@t{++} template function, and |
| 3291 | a newly loaded shared library has an instantiation of that template, |
| 3292 | a new location is added to the list of locations for the breakpoint. |
| 3293 | |
| 3294 | Except for having unresolved address, pending breakpoints do not |
| 3295 | differ from regular breakpoints. You can set conditions or commands, |
| 3296 | enable and disable them and perform other breakpoint operations. |
| 3297 | |
| 3298 | @value{GDBN} provides some additional commands for controlling what |
| 3299 | happens when the @samp{break} command cannot resolve breakpoint |
| 3300 | address specification to an address: |
| 3301 | |
| 3302 | @kindex set breakpoint pending |
| 3303 | @kindex show breakpoint pending |
| 3304 | @table @code |
| 3305 | @item set breakpoint pending auto |
| 3306 | This is the default behavior. When @value{GDBN} cannot find the breakpoint |
| 3307 | location, it queries you whether a pending breakpoint should be created. |
| 3308 | |
| 3309 | @item set breakpoint pending on |
| 3310 | This indicates that an unrecognized breakpoint location should automatically |
| 3311 | result in a pending breakpoint being created. |
| 3312 | |
| 3313 | @item set breakpoint pending off |
| 3314 | This indicates that pending breakpoints are not to be created. Any |
| 3315 | unrecognized breakpoint location results in an error. This setting does |
| 3316 | not affect any pending breakpoints previously created. |
| 3317 | |
| 3318 | @item show breakpoint pending |
| 3319 | Show the current behavior setting for creating pending breakpoints. |
| 3320 | @end table |
| 3321 | |
| 3322 | The settings above only affect the @code{break} command and its |
| 3323 | variants. Once breakpoint is set, it will be automatically updated |
| 3324 | as shared libraries are loaded and unloaded. |
| 3325 | |
| 3326 | @cindex automatic hardware breakpoints |
| 3327 | For some targets, @value{GDBN} can automatically decide if hardware or |
| 3328 | software breakpoints should be used, depending on whether the |
| 3329 | breakpoint address is read-only or read-write. This applies to |
| 3330 | breakpoints set with the @code{break} command as well as to internal |
| 3331 | breakpoints set by commands like @code{next} and @code{finish}. For |
| 3332 | breakpoints set with @code{hbreak}, @value{GDBN} will always use hardware |
| 3333 | breakpoints. |
| 3334 | |
| 3335 | You can control this automatic behaviour with the following commands:: |
| 3336 | |
| 3337 | @kindex set breakpoint auto-hw |
| 3338 | @kindex show breakpoint auto-hw |
| 3339 | @table @code |
| 3340 | @item set breakpoint auto-hw on |
| 3341 | This is the default behavior. When @value{GDBN} sets a breakpoint, it |
| 3342 | will try to use the target memory map to decide if software or hardware |
| 3343 | breakpoint must be used. |
| 3344 | |
| 3345 | @item set breakpoint auto-hw off |
| 3346 | This indicates @value{GDBN} should not automatically select breakpoint |
| 3347 | type. If the target provides a memory map, @value{GDBN} will warn when |
| 3348 | trying to set software breakpoint at a read-only address. |
| 3349 | @end table |
| 3350 | |
| 3351 | @value{GDBN} normally implements breakpoints by replacing the program code |
| 3352 | at the breakpoint address with a special instruction, which, when |
| 3353 | executed, given control to the debugger. By default, the program |
| 3354 | code is so modified only when the program is resumed. As soon as |
| 3355 | the program stops, @value{GDBN} restores the original instructions. This |
| 3356 | behaviour guards against leaving breakpoints inserted in the |
| 3357 | target should gdb abrubptly disconnect. However, with slow remote |
| 3358 | targets, inserting and removing breakpoint can reduce the performance. |
| 3359 | This behavior can be controlled with the following commands:: |
| 3360 | |
| 3361 | @kindex set breakpoint always-inserted |
| 3362 | @kindex show breakpoint always-inserted |
| 3363 | @table @code |
| 3364 | @item set breakpoint always-inserted off |
| 3365 | All breakpoints, including newly added by the user, are inserted in |
| 3366 | the target only when the target is resumed. All breakpoints are |
| 3367 | removed from the target when it stops. |
| 3368 | |
| 3369 | @item set breakpoint always-inserted on |
| 3370 | Causes all breakpoints to be inserted in the target at all times. If |
| 3371 | the user adds a new breakpoint, or changes an existing breakpoint, the |
| 3372 | breakpoints in the target are updated immediately. A breakpoint is |
| 3373 | removed from the target only when breakpoint itself is removed. |
| 3374 | |
| 3375 | @cindex non-stop mode, and @code{breakpoint always-inserted} |
| 3376 | @item set breakpoint always-inserted auto |
| 3377 | This is the default mode. If @value{GDBN} is controlling the inferior |
| 3378 | in non-stop mode (@pxref{Non-Stop Mode}), gdb behaves as if |
| 3379 | @code{breakpoint always-inserted} mode is on. If @value{GDBN} is |
| 3380 | controlling the inferior in all-stop mode, @value{GDBN} behaves as if |
| 3381 | @code{breakpoint always-inserted} mode is off. |
| 3382 | @end table |
| 3383 | |
| 3384 | @cindex negative breakpoint numbers |
| 3385 | @cindex internal @value{GDBN} breakpoints |
| 3386 | @value{GDBN} itself sometimes sets breakpoints in your program for |
| 3387 | special purposes, such as proper handling of @code{longjmp} (in C |
| 3388 | programs). These internal breakpoints are assigned negative numbers, |
| 3389 | starting with @code{-1}; @samp{info breakpoints} does not display them. |
| 3390 | You can see these breakpoints with the @value{GDBN} maintenance command |
| 3391 | @samp{maint info breakpoints} (@pxref{maint info breakpoints}). |
| 3392 | |
| 3393 | |
| 3394 | @node Set Watchpoints |
| 3395 | @subsection Setting Watchpoints |
| 3396 | |
| 3397 | @cindex setting watchpoints |
| 3398 | You can use a watchpoint to stop execution whenever the value of an |
| 3399 | expression changes, without having to predict a particular place where |
| 3400 | this may happen. (This is sometimes called a @dfn{data breakpoint}.) |
| 3401 | The expression may be as simple as the value of a single variable, or |
| 3402 | as complex as many variables combined by operators. Examples include: |
| 3403 | |
| 3404 | @itemize @bullet |
| 3405 | @item |
| 3406 | A reference to the value of a single variable. |
| 3407 | |
| 3408 | @item |
| 3409 | An address cast to an appropriate data type. For example, |
| 3410 | @samp{*(int *)0x12345678} will watch a 4-byte region at the specified |
| 3411 | address (assuming an @code{int} occupies 4 bytes). |
| 3412 | |
| 3413 | @item |
| 3414 | An arbitrarily complex expression, such as @samp{a*b + c/d}. The |
| 3415 | expression can use any operators valid in the program's native |
| 3416 | language (@pxref{Languages}). |
| 3417 | @end itemize |
| 3418 | |
| 3419 | You can set a watchpoint on an expression even if the expression can |
| 3420 | not be evaluated yet. For instance, you can set a watchpoint on |
| 3421 | @samp{*global_ptr} before @samp{global_ptr} is initialized. |
| 3422 | @value{GDBN} will stop when your program sets @samp{global_ptr} and |
| 3423 | the expression produces a valid value. If the expression becomes |
| 3424 | valid in some other way than changing a variable (e.g.@: if the memory |
| 3425 | pointed to by @samp{*global_ptr} becomes readable as the result of a |
| 3426 | @code{malloc} call), @value{GDBN} may not stop until the next time |
| 3427 | the expression changes. |
| 3428 | |
| 3429 | @cindex software watchpoints |
| 3430 | @cindex hardware watchpoints |
| 3431 | Depending on your system, watchpoints may be implemented in software or |
| 3432 | hardware. @value{GDBN} does software watchpointing by single-stepping your |
| 3433 | program and testing the variable's value each time, which is hundreds of |
| 3434 | times slower than normal execution. (But this may still be worth it, to |
| 3435 | catch errors where you have no clue what part of your program is the |
| 3436 | culprit.) |
| 3437 | |
| 3438 | On some systems, such as HP-UX, PowerPC, @sc{gnu}/Linux and most other |
| 3439 | x86-based targets, @value{GDBN} includes support for hardware |
| 3440 | watchpoints, which do not slow down the running of your program. |
| 3441 | |
| 3442 | @table @code |
| 3443 | @kindex watch |
| 3444 | @item watch @var{expr} @r{[}thread @var{threadnum}@r{]} |
| 3445 | Set a watchpoint for an expression. @value{GDBN} will break when the |
| 3446 | expression @var{expr} is written into by the program and its value |
| 3447 | changes. The simplest (and the most popular) use of this command is |
| 3448 | to watch the value of a single variable: |
| 3449 | |
| 3450 | @smallexample |
| 3451 | (@value{GDBP}) watch foo |
| 3452 | @end smallexample |
| 3453 | |
| 3454 | If the command includes a @code{@r{[}thread @var{threadnum}@r{]}} |
| 3455 | clause, @value{GDBN} breaks only when the thread identified by |
| 3456 | @var{threadnum} changes the value of @var{expr}. If any other threads |
| 3457 | change the value of @var{expr}, @value{GDBN} will not break. Note |
| 3458 | that watchpoints restricted to a single thread in this way only work |
| 3459 | with Hardware Watchpoints. |
| 3460 | |
| 3461 | @kindex rwatch |
| 3462 | @item rwatch @var{expr} @r{[}thread @var{threadnum}@r{]} |
| 3463 | Set a watchpoint that will break when the value of @var{expr} is read |
| 3464 | by the program. |
| 3465 | |
| 3466 | @kindex awatch |
| 3467 | @item awatch @var{expr} @r{[}thread @var{threadnum}@r{]} |
| 3468 | Set a watchpoint that will break when @var{expr} is either read from |
| 3469 | or written into by the program. |
| 3470 | |
| 3471 | @kindex info watchpoints @r{[}@var{n}@r{]} |
| 3472 | @item info watchpoints |
| 3473 | This command prints a list of watchpoints, breakpoints, and catchpoints; |
| 3474 | it is the same as @code{info break} (@pxref{Set Breaks}). |
| 3475 | @end table |
| 3476 | |
| 3477 | @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware |
| 3478 | watchpoints execute very quickly, and the debugger reports a change in |
| 3479 | value at the exact instruction where the change occurs. If @value{GDBN} |
| 3480 | cannot set a hardware watchpoint, it sets a software watchpoint, which |
| 3481 | executes more slowly and reports the change in value at the next |
| 3482 | @emph{statement}, not the instruction, after the change occurs. |
| 3483 | |
| 3484 | @cindex use only software watchpoints |
| 3485 | You can force @value{GDBN} to use only software watchpoints with the |
| 3486 | @kbd{set can-use-hw-watchpoints 0} command. With this variable set to |
| 3487 | zero, @value{GDBN} will never try to use hardware watchpoints, even if |
| 3488 | the underlying system supports them. (Note that hardware-assisted |
| 3489 | watchpoints that were set @emph{before} setting |
| 3490 | @code{can-use-hw-watchpoints} to zero will still use the hardware |
| 3491 | mechanism of watching expression values.) |
| 3492 | |
| 3493 | @table @code |
| 3494 | @item set can-use-hw-watchpoints |
| 3495 | @kindex set can-use-hw-watchpoints |
| 3496 | Set whether or not to use hardware watchpoints. |
| 3497 | |
| 3498 | @item show can-use-hw-watchpoints |
| 3499 | @kindex show can-use-hw-watchpoints |
| 3500 | Show the current mode of using hardware watchpoints. |
| 3501 | @end table |
| 3502 | |
| 3503 | For remote targets, you can restrict the number of hardware |
| 3504 | watchpoints @value{GDBN} will use, see @ref{set remote |
| 3505 | hardware-breakpoint-limit}. |
| 3506 | |
| 3507 | When you issue the @code{watch} command, @value{GDBN} reports |
| 3508 | |
| 3509 | @smallexample |
| 3510 | Hardware watchpoint @var{num}: @var{expr} |
| 3511 | @end smallexample |
| 3512 | |
| 3513 | @noindent |
| 3514 | if it was able to set a hardware watchpoint. |
| 3515 | |
| 3516 | Currently, the @code{awatch} and @code{rwatch} commands can only set |
| 3517 | hardware watchpoints, because accesses to data that don't change the |
| 3518 | value of the watched expression cannot be detected without examining |
| 3519 | every instruction as it is being executed, and @value{GDBN} does not do |
| 3520 | that currently. If @value{GDBN} finds that it is unable to set a |
| 3521 | hardware breakpoint with the @code{awatch} or @code{rwatch} command, it |
| 3522 | will print a message like this: |
| 3523 | |
| 3524 | @smallexample |
| 3525 | Expression cannot be implemented with read/access watchpoint. |
| 3526 | @end smallexample |
| 3527 | |
| 3528 | Sometimes, @value{GDBN} cannot set a hardware watchpoint because the |
| 3529 | data type of the watched expression is wider than what a hardware |
| 3530 | watchpoint on the target machine can handle. For example, some systems |
| 3531 | can only watch regions that are up to 4 bytes wide; on such systems you |
| 3532 | cannot set hardware watchpoints for an expression that yields a |
| 3533 | double-precision floating-point number (which is typically 8 bytes |
| 3534 | wide). As a work-around, it might be possible to break the large region |
| 3535 | into a series of smaller ones and watch them with separate watchpoints. |
| 3536 | |
| 3537 | If you set too many hardware watchpoints, @value{GDBN} might be unable |
| 3538 | to insert all of them when you resume the execution of your program. |
| 3539 | Since the precise number of active watchpoints is unknown until such |
| 3540 | time as the program is about to be resumed, @value{GDBN} might not be |
| 3541 | able to warn you about this when you set the watchpoints, and the |
| 3542 | warning will be printed only when the program is resumed: |
| 3543 | |
| 3544 | @smallexample |
| 3545 | Hardware watchpoint @var{num}: Could not insert watchpoint |
| 3546 | @end smallexample |
| 3547 | |
| 3548 | @noindent |
| 3549 | If this happens, delete or disable some of the watchpoints. |
| 3550 | |
| 3551 | Watching complex expressions that reference many variables can also |
| 3552 | exhaust the resources available for hardware-assisted watchpoints. |
| 3553 | That's because @value{GDBN} needs to watch every variable in the |
| 3554 | expression with separately allocated resources. |
| 3555 | |
| 3556 | If you call a function interactively using @code{print} or @code{call}, |
| 3557 | any watchpoints you have set will be inactive until @value{GDBN} reaches another |
| 3558 | kind of breakpoint or the call completes. |
| 3559 | |
| 3560 | @value{GDBN} automatically deletes watchpoints that watch local |
| 3561 | (automatic) variables, or expressions that involve such variables, when |
| 3562 | they go out of scope, that is, when the execution leaves the block in |
| 3563 | which these variables were defined. In particular, when the program |
| 3564 | being debugged terminates, @emph{all} local variables go out of scope, |
| 3565 | and so only watchpoints that watch global variables remain set. If you |
| 3566 | rerun the program, you will need to set all such watchpoints again. One |
| 3567 | way of doing that would be to set a code breakpoint at the entry to the |
| 3568 | @code{main} function and when it breaks, set all the watchpoints. |
| 3569 | |
| 3570 | @cindex watchpoints and threads |
| 3571 | @cindex threads and watchpoints |
| 3572 | In multi-threaded programs, watchpoints will detect changes to the |
| 3573 | watched expression from every thread. |
| 3574 | |
| 3575 | @quotation |
| 3576 | @emph{Warning:} In multi-threaded programs, software watchpoints |
| 3577 | have only limited usefulness. If @value{GDBN} creates a software |
| 3578 | watchpoint, it can only watch the value of an expression @emph{in a |
| 3579 | single thread}. If you are confident that the expression can only |
| 3580 | change due to the current thread's activity (and if you are also |
| 3581 | confident that no other thread can become current), then you can use |
| 3582 | software watchpoints as usual. However, @value{GDBN} may not notice |
| 3583 | when a non-current thread's activity changes the expression. (Hardware |
| 3584 | watchpoints, in contrast, watch an expression in all threads.) |
| 3585 | @end quotation |
| 3586 | |
| 3587 | @xref{set remote hardware-watchpoint-limit}. |
| 3588 | |
| 3589 | @node Set Catchpoints |
| 3590 | @subsection Setting Catchpoints |
| 3591 | @cindex catchpoints, setting |
| 3592 | @cindex exception handlers |
| 3593 | @cindex event handling |
| 3594 | |
| 3595 | You can use @dfn{catchpoints} to cause the debugger to stop for certain |
| 3596 | kinds of program events, such as C@t{++} exceptions or the loading of a |
| 3597 | shared library. Use the @code{catch} command to set a catchpoint. |
| 3598 | |
| 3599 | @table @code |
| 3600 | @kindex catch |
| 3601 | @item catch @var{event} |
| 3602 | Stop when @var{event} occurs. @var{event} can be any of the following: |
| 3603 | @table @code |
| 3604 | @item throw |
| 3605 | @cindex stop on C@t{++} exceptions |
| 3606 | The throwing of a C@t{++} exception. |
| 3607 | |
| 3608 | @item catch |
| 3609 | The catching of a C@t{++} exception. |
| 3610 | |
| 3611 | @item exception |
| 3612 | @cindex Ada exception catching |
| 3613 | @cindex catch Ada exceptions |
| 3614 | An Ada exception being raised. If an exception name is specified |
| 3615 | at the end of the command (eg @code{catch exception Program_Error}), |
| 3616 | the debugger will stop only when this specific exception is raised. |
| 3617 | Otherwise, the debugger stops execution when any Ada exception is raised. |
| 3618 | |
| 3619 | When inserting an exception catchpoint on a user-defined exception whose |
| 3620 | name is identical to one of the exceptions defined by the language, the |
| 3621 | fully qualified name must be used as the exception name. Otherwise, |
| 3622 | @value{GDBN} will assume that it should stop on the pre-defined exception |
| 3623 | rather than the user-defined one. For instance, assuming an exception |
| 3624 | called @code{Constraint_Error} is defined in package @code{Pck}, then |
| 3625 | the command to use to catch such exceptions is @kbd{catch exception |
| 3626 | Pck.Constraint_Error}. |
| 3627 | |
| 3628 | @item exception unhandled |
| 3629 | An exception that was raised but is not handled by the program. |
| 3630 | |
| 3631 | @item assert |
| 3632 | A failed Ada assertion. |
| 3633 | |
| 3634 | @item exec |
| 3635 | @cindex break on fork/exec |
| 3636 | A call to @code{exec}. This is currently only available for HP-UX |
| 3637 | and @sc{gnu}/Linux. |
| 3638 | |
| 3639 | @item fork |
| 3640 | A call to @code{fork}. This is currently only available for HP-UX |
| 3641 | and @sc{gnu}/Linux. |
| 3642 | |
| 3643 | @item vfork |
| 3644 | A call to @code{vfork}. This is currently only available for HP-UX |
| 3645 | and @sc{gnu}/Linux. |
| 3646 | |
| 3647 | @end table |
| 3648 | |
| 3649 | @item tcatch @var{event} |
| 3650 | Set a catchpoint that is enabled only for one stop. The catchpoint is |
| 3651 | automatically deleted after the first time the event is caught. |
| 3652 | |
| 3653 | @end table |
| 3654 | |
| 3655 | Use the @code{info break} command to list the current catchpoints. |
| 3656 | |
| 3657 | There are currently some limitations to C@t{++} exception handling |
| 3658 | (@code{catch throw} and @code{catch catch}) in @value{GDBN}: |
| 3659 | |
| 3660 | @itemize @bullet |
| 3661 | @item |
| 3662 | If you call a function interactively, @value{GDBN} normally returns |
| 3663 | control to you when the function has finished executing. If the call |
| 3664 | raises an exception, however, the call may bypass the mechanism that |
| 3665 | returns control to you and cause your program either to abort or to |
| 3666 | simply continue running until it hits a breakpoint, catches a signal |
| 3667 | that @value{GDBN} is listening for, or exits. This is the case even if |
| 3668 | you set a catchpoint for the exception; catchpoints on exceptions are |
| 3669 | disabled within interactive calls. |
| 3670 | |
| 3671 | @item |
| 3672 | You cannot raise an exception interactively. |
| 3673 | |
| 3674 | @item |
| 3675 | You cannot install an exception handler interactively. |
| 3676 | @end itemize |
| 3677 | |
| 3678 | @cindex raise exceptions |
| 3679 | Sometimes @code{catch} is not the best way to debug exception handling: |
| 3680 | if you need to know exactly where an exception is raised, it is better to |
| 3681 | stop @emph{before} the exception handler is called, since that way you |
| 3682 | can see the stack before any unwinding takes place. If you set a |
| 3683 | breakpoint in an exception handler instead, it may not be easy to find |
| 3684 | out where the exception was raised. |
| 3685 | |
| 3686 | To stop just before an exception handler is called, you need some |
| 3687 | knowledge of the implementation. In the case of @sc{gnu} C@t{++}, exceptions are |
| 3688 | raised by calling a library function named @code{__raise_exception} |
| 3689 | which has the following ANSI C interface: |
| 3690 | |
| 3691 | @smallexample |
| 3692 | /* @var{addr} is where the exception identifier is stored. |
| 3693 | @var{id} is the exception identifier. */ |
| 3694 | void __raise_exception (void **addr, void *id); |
| 3695 | @end smallexample |
| 3696 | |
| 3697 | @noindent |
| 3698 | To make the debugger catch all exceptions before any stack |
| 3699 | unwinding takes place, set a breakpoint on @code{__raise_exception} |
| 3700 | (@pxref{Breakpoints, ,Breakpoints; Watchpoints; and Exceptions}). |
| 3701 | |
| 3702 | With a conditional breakpoint (@pxref{Conditions, ,Break Conditions}) |
| 3703 | that depends on the value of @var{id}, you can stop your program when |
| 3704 | a specific exception is raised. You can use multiple conditional |
| 3705 | breakpoints to stop your program when any of a number of exceptions are |
| 3706 | raised. |
| 3707 | |
| 3708 | |
| 3709 | @node Delete Breaks |
| 3710 | @subsection Deleting Breakpoints |
| 3711 | |
| 3712 | @cindex clearing breakpoints, watchpoints, catchpoints |
| 3713 | @cindex deleting breakpoints, watchpoints, catchpoints |
| 3714 | It is often necessary to eliminate a breakpoint, watchpoint, or |
| 3715 | catchpoint once it has done its job and you no longer want your program |
| 3716 | to stop there. This is called @dfn{deleting} the breakpoint. A |
| 3717 | breakpoint that has been deleted no longer exists; it is forgotten. |
| 3718 | |
| 3719 | With the @code{clear} command you can delete breakpoints according to |
| 3720 | where they are in your program. With the @code{delete} command you can |
| 3721 | delete individual breakpoints, watchpoints, or catchpoints by specifying |
| 3722 | their breakpoint numbers. |
| 3723 | |
| 3724 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} |
| 3725 | automatically ignores breakpoints on the first instruction to be executed |
| 3726 | when you continue execution without changing the execution address. |
| 3727 | |
| 3728 | @table @code |
| 3729 | @kindex clear |
| 3730 | @item clear |
| 3731 | Delete any breakpoints at the next instruction to be executed in the |
| 3732 | selected stack frame (@pxref{Selection, ,Selecting a Frame}). When |
| 3733 | the innermost frame is selected, this is a good way to delete a |
| 3734 | breakpoint where your program just stopped. |
| 3735 | |
| 3736 | @item clear @var{location} |
| 3737 | Delete any breakpoints set at the specified @var{location}. |
| 3738 | @xref{Specify Location}, for the various forms of @var{location}; the |
| 3739 | most useful ones are listed below: |
| 3740 | |
| 3741 | @table @code |
| 3742 | @item clear @var{function} |
| 3743 | @itemx clear @var{filename}:@var{function} |
| 3744 | Delete any breakpoints set at entry to the named @var{function}. |
| 3745 | |
| 3746 | @item clear @var{linenum} |
| 3747 | @itemx clear @var{filename}:@var{linenum} |
| 3748 | Delete any breakpoints set at or within the code of the specified |
| 3749 | @var{linenum} of the specified @var{filename}. |
| 3750 | @end table |
| 3751 | |
| 3752 | @cindex delete breakpoints |
| 3753 | @kindex delete |
| 3754 | @kindex d @r{(@code{delete})} |
| 3755 | @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 3756 | Delete the breakpoints, watchpoints, or catchpoints of the breakpoint |
| 3757 | ranges specified as arguments. If no argument is specified, delete all |
| 3758 | breakpoints (@value{GDBN} asks confirmation, unless you have @code{set |
| 3759 | confirm off}). You can abbreviate this command as @code{d}. |
| 3760 | @end table |
| 3761 | |
| 3762 | @node Disabling |
| 3763 | @subsection Disabling Breakpoints |
| 3764 | |
| 3765 | @cindex enable/disable a breakpoint |
| 3766 | Rather than deleting a breakpoint, watchpoint, or catchpoint, you might |
| 3767 | prefer to @dfn{disable} it. This makes the breakpoint inoperative as if |
| 3768 | it had been deleted, but remembers the information on the breakpoint so |
| 3769 | that you can @dfn{enable} it again later. |
| 3770 | |
| 3771 | You disable and enable breakpoints, watchpoints, and catchpoints with |
| 3772 | the @code{enable} and @code{disable} commands, optionally specifying one |
| 3773 | or more breakpoint numbers as arguments. Use @code{info break} or |
| 3774 | @code{info watch} to print a list of breakpoints, watchpoints, and |
| 3775 | catchpoints if you do not know which numbers to use. |
| 3776 | |
| 3777 | Disabling and enabling a breakpoint that has multiple locations |
| 3778 | affects all of its locations. |
| 3779 | |
| 3780 | A breakpoint, watchpoint, or catchpoint can have any of four different |
| 3781 | states of enablement: |
| 3782 | |
| 3783 | @itemize @bullet |
| 3784 | @item |
| 3785 | Enabled. The breakpoint stops your program. A breakpoint set |
| 3786 | with the @code{break} command starts out in this state. |
| 3787 | @item |
| 3788 | Disabled. The breakpoint has no effect on your program. |
| 3789 | @item |
| 3790 | Enabled once. The breakpoint stops your program, but then becomes |
| 3791 | disabled. |
| 3792 | @item |
| 3793 | Enabled for deletion. The breakpoint stops your program, but |
| 3794 | immediately after it does so it is deleted permanently. A breakpoint |
| 3795 | set with the @code{tbreak} command starts out in this state. |
| 3796 | @end itemize |
| 3797 | |
| 3798 | You can use the following commands to enable or disable breakpoints, |
| 3799 | watchpoints, and catchpoints: |
| 3800 | |
| 3801 | @table @code |
| 3802 | @kindex disable |
| 3803 | @kindex dis @r{(@code{disable})} |
| 3804 | @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 3805 | Disable the specified breakpoints---or all breakpoints, if none are |
| 3806 | listed. A disabled breakpoint has no effect but is not forgotten. All |
| 3807 | options such as ignore-counts, conditions and commands are remembered in |
| 3808 | case the breakpoint is enabled again later. You may abbreviate |
| 3809 | @code{disable} as @code{dis}. |
| 3810 | |
| 3811 | @kindex enable |
| 3812 | @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 3813 | Enable the specified breakpoints (or all defined breakpoints). They |
| 3814 | become effective once again in stopping your program. |
| 3815 | |
| 3816 | @item enable @r{[}breakpoints@r{]} once @var{range}@dots{} |
| 3817 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
| 3818 | of these breakpoints immediately after stopping your program. |
| 3819 | |
| 3820 | @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{} |
| 3821 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
| 3822 | deletes any of these breakpoints as soon as your program stops there. |
| 3823 | Breakpoints set by the @code{tbreak} command start out in this state. |
| 3824 | @end table |
| 3825 | |
| 3826 | @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is |
| 3827 | @c confusing: tbreak is also initially enabled. |
| 3828 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
| 3829 | ,Setting Breakpoints}), breakpoints that you set are initially enabled; |
| 3830 | subsequently, they become disabled or enabled only when you use one of |
| 3831 | the commands above. (The command @code{until} can set and delete a |
| 3832 | breakpoint of its own, but it does not change the state of your other |
| 3833 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and |
| 3834 | Stepping}.) |
| 3835 | |
| 3836 | @node Conditions |
| 3837 | @subsection Break Conditions |
| 3838 | @cindex conditional breakpoints |
| 3839 | @cindex breakpoint conditions |
| 3840 | |
| 3841 | @c FIXME what is scope of break condition expr? Context where wanted? |
| 3842 | @c in particular for a watchpoint? |
| 3843 | The simplest sort of breakpoint breaks every time your program reaches a |
| 3844 | specified place. You can also specify a @dfn{condition} for a |
| 3845 | breakpoint. A condition is just a Boolean expression in your |
| 3846 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with |
| 3847 | a condition evaluates the expression each time your program reaches it, |
| 3848 | and your program stops only if the condition is @emph{true}. |
| 3849 | |
| 3850 | This is the converse of using assertions for program validation; in that |
| 3851 | situation, you want to stop when the assertion is violated---that is, |
| 3852 | when the condition is false. In C, if you want to test an assertion expressed |
| 3853 | by the condition @var{assert}, you should set the condition |
| 3854 | @samp{! @var{assert}} on the appropriate breakpoint. |
| 3855 | |
| 3856 | Conditions are also accepted for watchpoints; you may not need them, |
| 3857 | since a watchpoint is inspecting the value of an expression anyhow---but |
| 3858 | it might be simpler, say, to just set a watchpoint on a variable name, |
| 3859 | and specify a condition that tests whether the new value is an interesting |
| 3860 | one. |
| 3861 | |
| 3862 | Break conditions can have side effects, and may even call functions in |
| 3863 | your program. This can be useful, for example, to activate functions |
| 3864 | that log program progress, or to use your own print functions to |
| 3865 | format special data structures. The effects are completely predictable |
| 3866 | unless there is another enabled breakpoint at the same address. (In |
| 3867 | that case, @value{GDBN} might see the other breakpoint first and stop your |
| 3868 | program without checking the condition of this one.) Note that |
| 3869 | breakpoint commands are usually more convenient and flexible than break |
| 3870 | conditions for the |
| 3871 | purpose of performing side effects when a breakpoint is reached |
| 3872 | (@pxref{Break Commands, ,Breakpoint Command Lists}). |
| 3873 | |
| 3874 | Break conditions can be specified when a breakpoint is set, by using |
| 3875 | @samp{if} in the arguments to the @code{break} command. @xref{Set |
| 3876 | Breaks, ,Setting Breakpoints}. They can also be changed at any time |
| 3877 | with the @code{condition} command. |
| 3878 | |
| 3879 | You can also use the @code{if} keyword with the @code{watch} command. |
| 3880 | The @code{catch} command does not recognize the @code{if} keyword; |
| 3881 | @code{condition} is the only way to impose a further condition on a |
| 3882 | catchpoint. |
| 3883 | |
| 3884 | @table @code |
| 3885 | @kindex condition |
| 3886 | @item condition @var{bnum} @var{expression} |
| 3887 | Specify @var{expression} as the break condition for breakpoint, |
| 3888 | watchpoint, or catchpoint number @var{bnum}. After you set a condition, |
| 3889 | breakpoint @var{bnum} stops your program only if the value of |
| 3890 | @var{expression} is true (nonzero, in C). When you use |
| 3891 | @code{condition}, @value{GDBN} checks @var{expression} immediately for |
| 3892 | syntactic correctness, and to determine whether symbols in it have |
| 3893 | referents in the context of your breakpoint. If @var{expression} uses |
| 3894 | symbols not referenced in the context of the breakpoint, @value{GDBN} |
| 3895 | prints an error message: |
| 3896 | |
| 3897 | @smallexample |
| 3898 | No symbol "foo" in current context. |
| 3899 | @end smallexample |
| 3900 | |
| 3901 | @noindent |
| 3902 | @value{GDBN} does |
| 3903 | not actually evaluate @var{expression} at the time the @code{condition} |
| 3904 | command (or a command that sets a breakpoint with a condition, like |
| 3905 | @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}. |
| 3906 | |
| 3907 | @item condition @var{bnum} |
| 3908 | Remove the condition from breakpoint number @var{bnum}. It becomes |
| 3909 | an ordinary unconditional breakpoint. |
| 3910 | @end table |
| 3911 | |
| 3912 | @cindex ignore count (of breakpoint) |
| 3913 | A special case of a breakpoint condition is to stop only when the |
| 3914 | breakpoint has been reached a certain number of times. This is so |
| 3915 | useful that there is a special way to do it, using the @dfn{ignore |
| 3916 | count} of the breakpoint. Every breakpoint has an ignore count, which |
| 3917 | is an integer. Most of the time, the ignore count is zero, and |
| 3918 | therefore has no effect. But if your program reaches a breakpoint whose |
| 3919 | ignore count is positive, then instead of stopping, it just decrements |
| 3920 | the ignore count by one and continues. As a result, if the ignore count |
| 3921 | value is @var{n}, the breakpoint does not stop the next @var{n} times |
| 3922 | your program reaches it. |
| 3923 | |
| 3924 | @table @code |
| 3925 | @kindex ignore |
| 3926 | @item ignore @var{bnum} @var{count} |
| 3927 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. |
| 3928 | The next @var{count} times the breakpoint is reached, your program's |
| 3929 | execution does not stop; other than to decrement the ignore count, @value{GDBN} |
| 3930 | takes no action. |
| 3931 | |
| 3932 | To make the breakpoint stop the next time it is reached, specify |
| 3933 | a count of zero. |
| 3934 | |
| 3935 | When you use @code{continue} to resume execution of your program from a |
| 3936 | breakpoint, you can specify an ignore count directly as an argument to |
| 3937 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and |
| 3938 | Stepping,,Continuing and Stepping}. |
| 3939 | |
| 3940 | If a breakpoint has a positive ignore count and a condition, the |
| 3941 | condition is not checked. Once the ignore count reaches zero, |
| 3942 | @value{GDBN} resumes checking the condition. |
| 3943 | |
| 3944 | You could achieve the effect of the ignore count with a condition such |
| 3945 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that |
| 3946 | is decremented each time. @xref{Convenience Vars, ,Convenience |
| 3947 | Variables}. |
| 3948 | @end table |
| 3949 | |
| 3950 | Ignore counts apply to breakpoints, watchpoints, and catchpoints. |
| 3951 | |
| 3952 | |
| 3953 | @node Break Commands |
| 3954 | @subsection Breakpoint Command Lists |
| 3955 | |
| 3956 | @cindex breakpoint commands |
| 3957 | You can give any breakpoint (or watchpoint or catchpoint) a series of |
| 3958 | commands to execute when your program stops due to that breakpoint. For |
| 3959 | example, you might want to print the values of certain expressions, or |
| 3960 | enable other breakpoints. |
| 3961 | |
| 3962 | @table @code |
| 3963 | @kindex commands |
| 3964 | @kindex end@r{ (breakpoint commands)} |
| 3965 | @item commands @r{[}@var{bnum}@r{]} |
| 3966 | @itemx @dots{} @var{command-list} @dots{} |
| 3967 | @itemx end |
| 3968 | Specify a list of commands for breakpoint number @var{bnum}. The commands |
| 3969 | themselves appear on the following lines. Type a line containing just |
| 3970 | @code{end} to terminate the commands. |
| 3971 | |
| 3972 | To remove all commands from a breakpoint, type @code{commands} and |
| 3973 | follow it immediately with @code{end}; that is, give no commands. |
| 3974 | |
| 3975 | With no @var{bnum} argument, @code{commands} refers to the last |
| 3976 | breakpoint, watchpoint, or catchpoint set (not to the breakpoint most |
| 3977 | recently encountered). |
| 3978 | @end table |
| 3979 | |
| 3980 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is |
| 3981 | disabled within a @var{command-list}. |
| 3982 | |
| 3983 | You can use breakpoint commands to start your program up again. Simply |
| 3984 | use the @code{continue} command, or @code{step}, or any other command |
| 3985 | that resumes execution. |
| 3986 | |
| 3987 | Any other commands in the command list, after a command that resumes |
| 3988 | execution, are ignored. This is because any time you resume execution |
| 3989 | (even with a simple @code{next} or @code{step}), you may encounter |
| 3990 | another breakpoint---which could have its own command list, leading to |
| 3991 | ambiguities about which list to execute. |
| 3992 | |
| 3993 | @kindex silent |
| 3994 | If the first command you specify in a command list is @code{silent}, the |
| 3995 | usual message about stopping at a breakpoint is not printed. This may |
| 3996 | be desirable for breakpoints that are to print a specific message and |
| 3997 | then continue. If none of the remaining commands print anything, you |
| 3998 | see no sign that the breakpoint was reached. @code{silent} is |
| 3999 | meaningful only at the beginning of a breakpoint command list. |
| 4000 | |
| 4001 | The commands @code{echo}, @code{output}, and @code{printf} allow you to |
| 4002 | print precisely controlled output, and are often useful in silent |
| 4003 | breakpoints. @xref{Output, ,Commands for Controlled Output}. |
| 4004 | |
| 4005 | For example, here is how you could use breakpoint commands to print the |
| 4006 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. |
| 4007 | |
| 4008 | @smallexample |
| 4009 | break foo if x>0 |
| 4010 | commands |
| 4011 | silent |
| 4012 | printf "x is %d\n",x |
| 4013 | cont |
| 4014 | end |
| 4015 | @end smallexample |
| 4016 | |
| 4017 | One application for breakpoint commands is to compensate for one bug so |
| 4018 | you can test for another. Put a breakpoint just after the erroneous line |
| 4019 | of code, give it a condition to detect the case in which something |
| 4020 | erroneous has been done, and give it commands to assign correct values |
| 4021 | to any variables that need them. End with the @code{continue} command |
| 4022 | so that your program does not stop, and start with the @code{silent} |
| 4023 | command so that no output is produced. Here is an example: |
| 4024 | |
| 4025 | @smallexample |
| 4026 | break 403 |
| 4027 | commands |
| 4028 | silent |
| 4029 | set x = y + 4 |
| 4030 | cont |
| 4031 | end |
| 4032 | @end smallexample |
| 4033 | |
| 4034 | @c @ifclear BARETARGET |
| 4035 | @node Error in Breakpoints |
| 4036 | @subsection ``Cannot insert breakpoints'' |
| 4037 | |
| 4038 | If you request too many active hardware-assisted breakpoints and |
| 4039 | watchpoints, you will see this error message: |
| 4040 | |
| 4041 | @c FIXME: the precise wording of this message may change; the relevant |
| 4042 | @c source change is not committed yet (Sep 3, 1999). |
| 4043 | @smallexample |
| 4044 | Stopped; cannot insert breakpoints. |
| 4045 | You may have requested too many hardware breakpoints and watchpoints. |
| 4046 | @end smallexample |
| 4047 | |
| 4048 | @noindent |
| 4049 | This message is printed when you attempt to resume the program, since |
| 4050 | only then @value{GDBN} knows exactly how many hardware breakpoints and |
| 4051 | watchpoints it needs to insert. |
| 4052 | |
| 4053 | When this message is printed, you need to disable or remove some of the |
| 4054 | hardware-assisted breakpoints and watchpoints, and then continue. |
| 4055 | |
| 4056 | @node Breakpoint-related Warnings |
| 4057 | @subsection ``Breakpoint address adjusted...'' |
| 4058 | @cindex breakpoint address adjusted |
| 4059 | |
| 4060 | Some processor architectures place constraints on the addresses at |
| 4061 | which breakpoints may be placed. For architectures thus constrained, |
| 4062 | @value{GDBN} will attempt to adjust the breakpoint's address to comply |
| 4063 | with the constraints dictated by the architecture. |
| 4064 | |
| 4065 | One example of such an architecture is the Fujitsu FR-V. The FR-V is |
| 4066 | a VLIW architecture in which a number of RISC-like instructions may be |
| 4067 | bundled together for parallel execution. The FR-V architecture |
| 4068 | constrains the location of a breakpoint instruction within such a |
| 4069 | bundle to the instruction with the lowest address. @value{GDBN} |
| 4070 | honors this constraint by adjusting a breakpoint's address to the |
| 4071 | first in the bundle. |
| 4072 | |
| 4073 | It is not uncommon for optimized code to have bundles which contain |
| 4074 | instructions from different source statements, thus it may happen that |
| 4075 | a breakpoint's address will be adjusted from one source statement to |
| 4076 | another. Since this adjustment may significantly alter @value{GDBN}'s |
| 4077 | breakpoint related behavior from what the user expects, a warning is |
| 4078 | printed when the breakpoint is first set and also when the breakpoint |
| 4079 | is hit. |
| 4080 | |
| 4081 | A warning like the one below is printed when setting a breakpoint |
| 4082 | that's been subject to address adjustment: |
| 4083 | |
| 4084 | @smallexample |
| 4085 | warning: Breakpoint address adjusted from 0x00010414 to 0x00010410. |
| 4086 | @end smallexample |
| 4087 | |
| 4088 | Such warnings are printed both for user settable and @value{GDBN}'s |
| 4089 | internal breakpoints. If you see one of these warnings, you should |
| 4090 | verify that a breakpoint set at the adjusted address will have the |
| 4091 | desired affect. If not, the breakpoint in question may be removed and |
| 4092 | other breakpoints may be set which will have the desired behavior. |
| 4093 | E.g., it may be sufficient to place the breakpoint at a later |
| 4094 | instruction. A conditional breakpoint may also be useful in some |
| 4095 | cases to prevent the breakpoint from triggering too often. |
| 4096 | |
| 4097 | @value{GDBN} will also issue a warning when stopping at one of these |
| 4098 | adjusted breakpoints: |
| 4099 | |
| 4100 | @smallexample |
| 4101 | warning: Breakpoint 1 address previously adjusted from 0x00010414 |
| 4102 | to 0x00010410. |
| 4103 | @end smallexample |
| 4104 | |
| 4105 | When this warning is encountered, it may be too late to take remedial |
| 4106 | action except in cases where the breakpoint is hit earlier or more |
| 4107 | frequently than expected. |
| 4108 | |
| 4109 | @node Continuing and Stepping |
| 4110 | @section Continuing and Stepping |
| 4111 | |
| 4112 | @cindex stepping |
| 4113 | @cindex continuing |
| 4114 | @cindex resuming execution |
| 4115 | @dfn{Continuing} means resuming program execution until your program |
| 4116 | completes normally. In contrast, @dfn{stepping} means executing just |
| 4117 | one more ``step'' of your program, where ``step'' may mean either one |
| 4118 | line of source code, or one machine instruction (depending on what |
| 4119 | particular command you use). Either when continuing or when stepping, |
| 4120 | your program may stop even sooner, due to a breakpoint or a signal. (If |
| 4121 | it stops due to a signal, you may want to use @code{handle}, or use |
| 4122 | @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.) |
| 4123 | |
| 4124 | @table @code |
| 4125 | @kindex continue |
| 4126 | @kindex c @r{(@code{continue})} |
| 4127 | @kindex fg @r{(resume foreground execution)} |
| 4128 | @item continue @r{[}@var{ignore-count}@r{]} |
| 4129 | @itemx c @r{[}@var{ignore-count}@r{]} |
| 4130 | @itemx fg @r{[}@var{ignore-count}@r{]} |
| 4131 | Resume program execution, at the address where your program last stopped; |
| 4132 | any breakpoints set at that address are bypassed. The optional argument |
| 4133 | @var{ignore-count} allows you to specify a further number of times to |
| 4134 | ignore a breakpoint at this location; its effect is like that of |
| 4135 | @code{ignore} (@pxref{Conditions, ,Break Conditions}). |
| 4136 | |
| 4137 | The argument @var{ignore-count} is meaningful only when your program |
| 4138 | stopped due to a breakpoint. At other times, the argument to |
| 4139 | @code{continue} is ignored. |
| 4140 | |
| 4141 | The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the |
| 4142 | debugged program is deemed to be the foreground program) are provided |
| 4143 | purely for convenience, and have exactly the same behavior as |
| 4144 | @code{continue}. |
| 4145 | @end table |
| 4146 | |
| 4147 | To resume execution at a different place, you can use @code{return} |
| 4148 | (@pxref{Returning, ,Returning from a Function}) to go back to the |
| 4149 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a |
| 4150 | Different Address}) to go to an arbitrary location in your program. |
| 4151 | |
| 4152 | A typical technique for using stepping is to set a breakpoint |
| 4153 | (@pxref{Breakpoints, ,Breakpoints; Watchpoints; and Catchpoints}) at the |
| 4154 | beginning of the function or the section of your program where a problem |
| 4155 | is believed to lie, run your program until it stops at that breakpoint, |
| 4156 | and then step through the suspect area, examining the variables that are |
| 4157 | interesting, until you see the problem happen. |
| 4158 | |
| 4159 | @table @code |
| 4160 | @kindex step |
| 4161 | @kindex s @r{(@code{step})} |
| 4162 | @item step |
| 4163 | Continue running your program until control reaches a different source |
| 4164 | line, then stop it and return control to @value{GDBN}. This command is |
| 4165 | abbreviated @code{s}. |
| 4166 | |
| 4167 | @quotation |
| 4168 | @c "without debugging information" is imprecise; actually "without line |
| 4169 | @c numbers in the debugging information". (gcc -g1 has debugging info but |
| 4170 | @c not line numbers). But it seems complex to try to make that |
| 4171 | @c distinction here. |
| 4172 | @emph{Warning:} If you use the @code{step} command while control is |
| 4173 | within a function that was compiled without debugging information, |
| 4174 | execution proceeds until control reaches a function that does have |
| 4175 | debugging information. Likewise, it will not step into a function which |
| 4176 | is compiled without debugging information. To step through functions |
| 4177 | without debugging information, use the @code{stepi} command, described |
| 4178 | below. |
| 4179 | @end quotation |
| 4180 | |
| 4181 | The @code{step} command only stops at the first instruction of a source |
| 4182 | line. This prevents the multiple stops that could otherwise occur in |
| 4183 | @code{switch} statements, @code{for} loops, etc. @code{step} continues |
| 4184 | to stop if a function that has debugging information is called within |
| 4185 | the line. In other words, @code{step} @emph{steps inside} any functions |
| 4186 | called within the line. |
| 4187 | |
| 4188 | Also, the @code{step} command only enters a function if there is line |
| 4189 | number information for the function. Otherwise it acts like the |
| 4190 | @code{next} command. This avoids problems when using @code{cc -gl} |
| 4191 | on MIPS machines. Previously, @code{step} entered subroutines if there |
| 4192 | was any debugging information about the routine. |
| 4193 | |
| 4194 | @item step @var{count} |
| 4195 | Continue running as in @code{step}, but do so @var{count} times. If a |
| 4196 | breakpoint is reached, or a signal not related to stepping occurs before |
| 4197 | @var{count} steps, stepping stops right away. |
| 4198 | |
| 4199 | @kindex next |
| 4200 | @kindex n @r{(@code{next})} |
| 4201 | @item next @r{[}@var{count}@r{]} |
| 4202 | Continue to the next source line in the current (innermost) stack frame. |
| 4203 | This is similar to @code{step}, but function calls that appear within |
| 4204 | the line of code are executed without stopping. Execution stops when |
| 4205 | control reaches a different line of code at the original stack level |
| 4206 | that was executing when you gave the @code{next} command. This command |
| 4207 | is abbreviated @code{n}. |
| 4208 | |
| 4209 | An argument @var{count} is a repeat count, as for @code{step}. |
| 4210 | |
| 4211 | |
| 4212 | @c FIX ME!! Do we delete this, or is there a way it fits in with |
| 4213 | @c the following paragraph? --- Vctoria |
| 4214 | @c |
| 4215 | @c @code{next} within a function that lacks debugging information acts like |
| 4216 | @c @code{step}, but any function calls appearing within the code of the |
| 4217 | @c function are executed without stopping. |
| 4218 | |
| 4219 | The @code{next} command only stops at the first instruction of a |
| 4220 | source line. This prevents multiple stops that could otherwise occur in |
| 4221 | @code{switch} statements, @code{for} loops, etc. |
| 4222 | |
| 4223 | @kindex set step-mode |
| 4224 | @item set step-mode |
| 4225 | @cindex functions without line info, and stepping |
| 4226 | @cindex stepping into functions with no line info |
| 4227 | @itemx set step-mode on |
| 4228 | The @code{set step-mode on} command causes the @code{step} command to |
| 4229 | stop at the first instruction of a function which contains no debug line |
| 4230 | information rather than stepping over it. |
| 4231 | |
| 4232 | This is useful in cases where you may be interested in inspecting the |
| 4233 | machine instructions of a function which has no symbolic info and do not |
| 4234 | want @value{GDBN} to automatically skip over this function. |
| 4235 | |
| 4236 | @item set step-mode off |
| 4237 | Causes the @code{step} command to step over any functions which contains no |
| 4238 | debug information. This is the default. |
| 4239 | |
| 4240 | @item show step-mode |
| 4241 | Show whether @value{GDBN} will stop in or step over functions without |
| 4242 | source line debug information. |
| 4243 | |
| 4244 | @kindex finish |
| 4245 | @kindex fin @r{(@code{finish})} |
| 4246 | @item finish |
| 4247 | Continue running until just after function in the selected stack frame |
| 4248 | returns. Print the returned value (if any). This command can be |
| 4249 | abbreviated as @code{fin}. |
| 4250 | |
| 4251 | Contrast this with the @code{return} command (@pxref{Returning, |
| 4252 | ,Returning from a Function}). |
| 4253 | |
| 4254 | @kindex until |
| 4255 | @kindex u @r{(@code{until})} |
| 4256 | @cindex run until specified location |
| 4257 | @item until |
| 4258 | @itemx u |
| 4259 | Continue running until a source line past the current line, in the |
| 4260 | current stack frame, is reached. This command is used to avoid single |
| 4261 | stepping through a loop more than once. It is like the @code{next} |
| 4262 | command, except that when @code{until} encounters a jump, it |
| 4263 | automatically continues execution until the program counter is greater |
| 4264 | than the address of the jump. |
| 4265 | |
| 4266 | This means that when you reach the end of a loop after single stepping |
| 4267 | though it, @code{until} makes your program continue execution until it |
| 4268 | exits the loop. In contrast, a @code{next} command at the end of a loop |
| 4269 | simply steps back to the beginning of the loop, which forces you to step |
| 4270 | through the next iteration. |
| 4271 | |
| 4272 | @code{until} always stops your program if it attempts to exit the current |
| 4273 | stack frame. |
| 4274 | |
| 4275 | @code{until} may produce somewhat counterintuitive results if the order |
| 4276 | of machine code does not match the order of the source lines. For |
| 4277 | example, in the following excerpt from a debugging session, the @code{f} |
| 4278 | (@code{frame}) command shows that execution is stopped at line |
| 4279 | @code{206}; yet when we use @code{until}, we get to line @code{195}: |
| 4280 | |
| 4281 | @smallexample |
| 4282 | (@value{GDBP}) f |
| 4283 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 |
| 4284 | 206 expand_input(); |
| 4285 | (@value{GDBP}) until |
| 4286 | 195 for ( ; argc > 0; NEXTARG) @{ |
| 4287 | @end smallexample |
| 4288 | |
| 4289 | This happened because, for execution efficiency, the compiler had |
| 4290 | generated code for the loop closure test at the end, rather than the |
| 4291 | start, of the loop---even though the test in a C @code{for}-loop is |
| 4292 | written before the body of the loop. The @code{until} command appeared |
| 4293 | to step back to the beginning of the loop when it advanced to this |
| 4294 | expression; however, it has not really gone to an earlier |
| 4295 | statement---not in terms of the actual machine code. |
| 4296 | |
| 4297 | @code{until} with no argument works by means of single |
| 4298 | instruction stepping, and hence is slower than @code{until} with an |
| 4299 | argument. |
| 4300 | |
| 4301 | @item until @var{location} |
| 4302 | @itemx u @var{location} |
| 4303 | Continue running your program until either the specified location is |
| 4304 | reached, or the current stack frame returns. @var{location} is any of |
| 4305 | the forms described in @ref{Specify Location}. |
| 4306 | This form of the command uses temporary breakpoints, and |
| 4307 | hence is quicker than @code{until} without an argument. The specified |
| 4308 | location is actually reached only if it is in the current frame. This |
| 4309 | implies that @code{until} can be used to skip over recursive function |
| 4310 | invocations. For instance in the code below, if the current location is |
| 4311 | line @code{96}, issuing @code{until 99} will execute the program up to |
| 4312 | line @code{99} in the same invocation of factorial, i.e., after the inner |
| 4313 | invocations have returned. |
| 4314 | |
| 4315 | @smallexample |
| 4316 | 94 int factorial (int value) |
| 4317 | 95 @{ |
| 4318 | 96 if (value > 1) @{ |
| 4319 | 97 value *= factorial (value - 1); |
| 4320 | 98 @} |
| 4321 | 99 return (value); |
| 4322 | 100 @} |
| 4323 | @end smallexample |
| 4324 | |
| 4325 | |
| 4326 | @kindex advance @var{location} |
| 4327 | @itemx advance @var{location} |
| 4328 | Continue running the program up to the given @var{location}. An argument is |
| 4329 | required, which should be of one of the forms described in |
| 4330 | @ref{Specify Location}. |
| 4331 | Execution will also stop upon exit from the current stack |
| 4332 | frame. This command is similar to @code{until}, but @code{advance} will |
| 4333 | not skip over recursive function calls, and the target location doesn't |
| 4334 | have to be in the same frame as the current one. |
| 4335 | |
| 4336 | |
| 4337 | @kindex stepi |
| 4338 | @kindex si @r{(@code{stepi})} |
| 4339 | @item stepi |
| 4340 | @itemx stepi @var{arg} |
| 4341 | @itemx si |
| 4342 | Execute one machine instruction, then stop and return to the debugger. |
| 4343 | |
| 4344 | It is often useful to do @samp{display/i $pc} when stepping by machine |
| 4345 | instructions. This makes @value{GDBN} automatically display the next |
| 4346 | instruction to be executed, each time your program stops. @xref{Auto |
| 4347 | Display,, Automatic Display}. |
| 4348 | |
| 4349 | An argument is a repeat count, as in @code{step}. |
| 4350 | |
| 4351 | @need 750 |
| 4352 | @kindex nexti |
| 4353 | @kindex ni @r{(@code{nexti})} |
| 4354 | @item nexti |
| 4355 | @itemx nexti @var{arg} |
| 4356 | @itemx ni |
| 4357 | Execute one machine instruction, but if it is a function call, |
| 4358 | proceed until the function returns. |
| 4359 | |
| 4360 | An argument is a repeat count, as in @code{next}. |
| 4361 | @end table |
| 4362 | |
| 4363 | @node Signals |
| 4364 | @section Signals |
| 4365 | @cindex signals |
| 4366 | |
| 4367 | A signal is an asynchronous event that can happen in a program. The |
| 4368 | operating system defines the possible kinds of signals, and gives each |
| 4369 | kind a name and a number. For example, in Unix @code{SIGINT} is the |
| 4370 | signal a program gets when you type an interrupt character (often @kbd{Ctrl-c}); |
| 4371 | @code{SIGSEGV} is the signal a program gets from referencing a place in |
| 4372 | memory far away from all the areas in use; @code{SIGALRM} occurs when |
| 4373 | the alarm clock timer goes off (which happens only if your program has |
| 4374 | requested an alarm). |
| 4375 | |
| 4376 | @cindex fatal signals |
| 4377 | Some signals, including @code{SIGALRM}, are a normal part of the |
| 4378 | functioning of your program. Others, such as @code{SIGSEGV}, indicate |
| 4379 | errors; these signals are @dfn{fatal} (they kill your program immediately) if the |
| 4380 | program has not specified in advance some other way to handle the signal. |
| 4381 | @code{SIGINT} does not indicate an error in your program, but it is normally |
| 4382 | fatal so it can carry out the purpose of the interrupt: to kill the program. |
| 4383 | |
| 4384 | @value{GDBN} has the ability to detect any occurrence of a signal in your |
| 4385 | program. You can tell @value{GDBN} in advance what to do for each kind of |
| 4386 | signal. |
| 4387 | |
| 4388 | @cindex handling signals |
| 4389 | Normally, @value{GDBN} is set up to let the non-erroneous signals like |
| 4390 | @code{SIGALRM} be silently passed to your program |
| 4391 | (so as not to interfere with their role in the program's functioning) |
| 4392 | but to stop your program immediately whenever an error signal happens. |
| 4393 | You can change these settings with the @code{handle} command. |
| 4394 | |
| 4395 | @table @code |
| 4396 | @kindex info signals |
| 4397 | @kindex info handle |
| 4398 | @item info signals |
| 4399 | @itemx info handle |
| 4400 | Print a table of all the kinds of signals and how @value{GDBN} has been told to |
| 4401 | handle each one. You can use this to see the signal numbers of all |
| 4402 | the defined types of signals. |
| 4403 | |
| 4404 | @item info signals @var{sig} |
| 4405 | Similar, but print information only about the specified signal number. |
| 4406 | |
| 4407 | @code{info handle} is an alias for @code{info signals}. |
| 4408 | |
| 4409 | @kindex handle |
| 4410 | @item handle @var{signal} @r{[}@var{keywords}@dots{}@r{]} |
| 4411 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} |
| 4412 | can be the number of a signal or its name (with or without the |
| 4413 | @samp{SIG} at the beginning); a list of signal numbers of the form |
| 4414 | @samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the |
| 4415 | known signals. Optional arguments @var{keywords}, described below, |
| 4416 | say what change to make. |
| 4417 | @end table |
| 4418 | |
| 4419 | @c @group |
| 4420 | The keywords allowed by the @code{handle} command can be abbreviated. |
| 4421 | Their full names are: |
| 4422 | |
| 4423 | @table @code |
| 4424 | @item nostop |
| 4425 | @value{GDBN} should not stop your program when this signal happens. It may |
| 4426 | still print a message telling you that the signal has come in. |
| 4427 | |
| 4428 | @item stop |
| 4429 | @value{GDBN} should stop your program when this signal happens. This implies |
| 4430 | the @code{print} keyword as well. |
| 4431 | |
| 4432 | @item print |
| 4433 | @value{GDBN} should print a message when this signal happens. |
| 4434 | |
| 4435 | @item noprint |
| 4436 | @value{GDBN} should not mention the occurrence of the signal at all. This |
| 4437 | implies the @code{nostop} keyword as well. |
| 4438 | |
| 4439 | @item pass |
| 4440 | @itemx noignore |
| 4441 | @value{GDBN} should allow your program to see this signal; your program |
| 4442 | can handle the signal, or else it may terminate if the signal is fatal |
| 4443 | and not handled. @code{pass} and @code{noignore} are synonyms. |
| 4444 | |
| 4445 | @item nopass |
| 4446 | @itemx ignore |
| 4447 | @value{GDBN} should not allow your program to see this signal. |
| 4448 | @code{nopass} and @code{ignore} are synonyms. |
| 4449 | @end table |
| 4450 | @c @end group |
| 4451 | |
| 4452 | When a signal stops your program, the signal is not visible to the |
| 4453 | program until you |
| 4454 | continue. Your program sees the signal then, if @code{pass} is in |
| 4455 | effect for the signal in question @emph{at that time}. In other words, |
| 4456 | after @value{GDBN} reports a signal, you can use the @code{handle} |
| 4457 | command with @code{pass} or @code{nopass} to control whether your |
| 4458 | program sees that signal when you continue. |
| 4459 | |
| 4460 | The default is set to @code{nostop}, @code{noprint}, @code{pass} for |
| 4461 | non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and |
| 4462 | @code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the |
| 4463 | erroneous signals. |
| 4464 | |
| 4465 | You can also use the @code{signal} command to prevent your program from |
| 4466 | seeing a signal, or cause it to see a signal it normally would not see, |
| 4467 | or to give it any signal at any time. For example, if your program stopped |
| 4468 | due to some sort of memory reference error, you might store correct |
| 4469 | values into the erroneous variables and continue, hoping to see more |
| 4470 | execution; but your program would probably terminate immediately as |
| 4471 | a result of the fatal signal once it saw the signal. To prevent this, |
| 4472 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your |
| 4473 | Program a Signal}. |
| 4474 | |
| 4475 | @node Thread Stops |
| 4476 | @section Stopping and Starting Multi-thread Programs |
| 4477 | |
| 4478 | @cindex stopped threads |
| 4479 | @cindex threads, stopped |
| 4480 | |
| 4481 | @cindex continuing threads |
| 4482 | @cindex threads, continuing |
| 4483 | |
| 4484 | @value{GDBN} supports debugging programs with multiple threads |
| 4485 | (@pxref{Threads,, Debugging Programs with Multiple Threads}). There |
| 4486 | are two modes of controlling execution of your program within the |
| 4487 | debugger. In the default mode, referred to as @dfn{all-stop mode}, |
| 4488 | when any thread in your program stops (for example, at a breakpoint |
| 4489 | or while being stepped), all other threads in the program are also stopped by |
| 4490 | @value{GDBN}. On some targets, @value{GDBN} also supports |
| 4491 | @dfn{non-stop mode}, in which other threads can continue to run freely while |
| 4492 | you examine the stopped thread in the debugger. |
| 4493 | |
| 4494 | @menu |
| 4495 | * All-Stop Mode:: All threads stop when GDB takes control |
| 4496 | * Non-Stop Mode:: Other threads continue to execute |
| 4497 | * Background Execution:: Running your program asynchronously |
| 4498 | * Thread-Specific Breakpoints:: Controlling breakpoints |
| 4499 | * Interrupted System Calls:: GDB may interfere with system calls |
| 4500 | @end menu |
| 4501 | |
| 4502 | @node All-Stop Mode |
| 4503 | @subsection All-Stop Mode |
| 4504 | |
| 4505 | @cindex all-stop mode |
| 4506 | |
| 4507 | In all-stop mode, whenever your program stops under @value{GDBN} for any reason, |
| 4508 | @emph{all} threads of execution stop, not just the current thread. This |
| 4509 | allows you to examine the overall state of the program, including |
| 4510 | switching between threads, without worrying that things may change |
| 4511 | underfoot. |
| 4512 | |
| 4513 | Conversely, whenever you restart the program, @emph{all} threads start |
| 4514 | executing. @emph{This is true even when single-stepping} with commands |
| 4515 | like @code{step} or @code{next}. |
| 4516 | |
| 4517 | In particular, @value{GDBN} cannot single-step all threads in lockstep. |
| 4518 | Since thread scheduling is up to your debugging target's operating |
| 4519 | system (not controlled by @value{GDBN}), other threads may |
| 4520 | execute more than one statement while the current thread completes a |
| 4521 | single step. Moreover, in general other threads stop in the middle of a |
| 4522 | statement, rather than at a clean statement boundary, when the program |
| 4523 | stops. |
| 4524 | |
| 4525 | You might even find your program stopped in another thread after |
| 4526 | continuing or even single-stepping. This happens whenever some other |
| 4527 | thread runs into a breakpoint, a signal, or an exception before the |
| 4528 | first thread completes whatever you requested. |
| 4529 | |
| 4530 | @cindex automatic thread selection |
| 4531 | @cindex switching threads automatically |
| 4532 | @cindex threads, automatic switching |
| 4533 | Whenever @value{GDBN} stops your program, due to a breakpoint or a |
| 4534 | signal, it automatically selects the thread where that breakpoint or |
| 4535 | signal happened. @value{GDBN} alerts you to the context switch with a |
| 4536 | message such as @samp{[Switching to Thread @var{n}]} to identify the |
| 4537 | thread. |
| 4538 | |
| 4539 | On some OSes, you can modify @value{GDBN}'s default behavior by |
| 4540 | locking the OS scheduler to allow only a single thread to run. |
| 4541 | |
| 4542 | @table @code |
| 4543 | @item set scheduler-locking @var{mode} |
| 4544 | @cindex scheduler locking mode |
| 4545 | @cindex lock scheduler |
| 4546 | Set the scheduler locking mode. If it is @code{off}, then there is no |
| 4547 | locking and any thread may run at any time. If @code{on}, then only the |
| 4548 | current thread may run when the inferior is resumed. The @code{step} |
| 4549 | mode optimizes for single-stepping; it prevents other threads |
| 4550 | from preempting the current thread while you are stepping, so that |
| 4551 | the focus of debugging does not change unexpectedly. |
| 4552 | Other threads only rarely (or never) get a chance to run |
| 4553 | when you step. They are more likely to run when you @samp{next} over a |
| 4554 | function call, and they are completely free to run when you use commands |
| 4555 | like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another |
| 4556 | thread hits a breakpoint during its timeslice, @value{GDBN} does not change |
| 4557 | the current thread away from the thread that you are debugging. |
| 4558 | |
| 4559 | @item show scheduler-locking |
| 4560 | Display the current scheduler locking mode. |
| 4561 | @end table |
| 4562 | |
| 4563 | @node Non-Stop Mode |
| 4564 | @subsection Non-Stop Mode |
| 4565 | |
| 4566 | @cindex non-stop mode |
| 4567 | |
| 4568 | @c This section is really only a place-holder, and needs to be expanded |
| 4569 | @c with more details. |
| 4570 | |
| 4571 | For some multi-threaded targets, @value{GDBN} supports an optional |
| 4572 | mode of operation in which you can examine stopped program threads in |
| 4573 | the debugger while other threads continue to execute freely. This |
| 4574 | minimizes intrusion when debugging live systems, such as programs |
| 4575 | where some threads have real-time constraints or must continue to |
| 4576 | respond to external events. This is referred to as @dfn{non-stop} mode. |
| 4577 | |
| 4578 | In non-stop mode, when a thread stops to report a debugging event, |
| 4579 | @emph{only} that thread is stopped; @value{GDBN} does not stop other |
| 4580 | threads as well, in contrast to the all-stop mode behavior. Additionally, |
| 4581 | execution commands such as @code{continue} and @code{step} apply by default |
| 4582 | only to the current thread in non-stop mode, rather than all threads as |
| 4583 | in all-stop mode. This allows you to control threads explicitly in |
| 4584 | ways that are not possible in all-stop mode --- for example, stepping |
| 4585 | one thread while allowing others to run freely, stepping |
| 4586 | one thread while holding all others stopped, or stepping several threads |
| 4587 | independently and simultaneously. |
| 4588 | |
| 4589 | To enter non-stop mode, use this sequence of commands before you run |
| 4590 | or attach to your program: |
| 4591 | |
| 4592 | @smallexample |
| 4593 | # Enable the async interface. |
| 4594 | set target-async 1 |
| 4595 | |
| 4596 | # If using the CLI, pagination breaks non-stop. |
| 4597 | set pagination off |
| 4598 | |
| 4599 | # Finally, turn it on! |
| 4600 | set non-stop on |
| 4601 | @end smallexample |
| 4602 | |
| 4603 | You can use these commands to manipulate the non-stop mode setting: |
| 4604 | |
| 4605 | @table @code |
| 4606 | @kindex set non-stop |
| 4607 | @item set non-stop on |
| 4608 | Enable selection of non-stop mode. |
| 4609 | @item set non-stop off |
| 4610 | Disable selection of non-stop mode. |
| 4611 | @kindex show non-stop |
| 4612 | @item show non-stop |
| 4613 | Show the current non-stop enablement setting. |
| 4614 | @end table |
| 4615 | |
| 4616 | Note these commands only reflect whether non-stop mode is enabled, |
| 4617 | not whether the currently-executing program is being run in non-stop mode. |
| 4618 | In particular, the @code{set non-stop} preference is only consulted when |
| 4619 | @value{GDBN} starts or connects to the target program, and it is generally |
| 4620 | not possible to switch modes once debugging has started. Furthermore, |
| 4621 | since not all targets support non-stop mode, even when you have enabled |
| 4622 | non-stop mode, @value{GDBN} may still fall back to all-stop operation by |
| 4623 | default. |
| 4624 | |
| 4625 | In non-stop mode, all execution commands apply only to the current thread |
| 4626 | by default. That is, @code{continue} only continues one thread. |
| 4627 | To continue all threads, issue @code{continue -a} or @code{c -a}. |
| 4628 | |
| 4629 | You can use @value{GDBN}'s background execution commands |
| 4630 | (@pxref{Background Execution}) to run some threads in the background |
| 4631 | while you continue to examine or step others from @value{GDBN}. |
| 4632 | The MI execution commands (@pxref{GDB/MI Program Execution}) are |
| 4633 | always executed asynchronously in non-stop mode. |
| 4634 | |
| 4635 | Suspending execution is done with the @code{interrupt} command when |
| 4636 | running in the background, or @kbd{Ctrl-c} during foreground execution. |
| 4637 | In all-stop mode, this stops the whole process; |
| 4638 | but in non-stop mode the interrupt applies only to the current thread. |
| 4639 | To stop the whole program, use @code{interrupt -a}. |
| 4640 | |
| 4641 | Other execution commands do not currently support the @code{-a} option. |
| 4642 | |
| 4643 | In non-stop mode, when a thread stops, @value{GDBN} doesn't automatically make |
| 4644 | that thread current, as it does in all-stop mode. This is because the |
| 4645 | thread stop notifications are asynchronous with respect to @value{GDBN}'s |
| 4646 | command interpreter, and it would be confusing if @value{GDBN} unexpectedly |
| 4647 | changed to a different thread just as you entered a command to operate on the |
| 4648 | previously current thread. |
| 4649 | |
| 4650 | @node Background Execution |
| 4651 | @subsection Background Execution |
| 4652 | |
| 4653 | @cindex foreground execution |
| 4654 | @cindex background execution |
| 4655 | @cindex asynchronous execution |
| 4656 | @cindex execution, foreground, background and asynchronous |
| 4657 | |
| 4658 | @value{GDBN}'s execution commands have two variants: the normal |
| 4659 | foreground (synchronous) behavior, and a background |
| 4660 | (asynchronous) behavior. In foreground execution, @value{GDBN} waits for |
| 4661 | the program to report that some thread has stopped before prompting for |
| 4662 | another command. In background execution, @value{GDBN} immediately gives |
| 4663 | a command prompt so that you can issue other commands while your program runs. |
| 4664 | |
| 4665 | To specify background execution, add a @code{&} to the command. For example, |
| 4666 | the background form of the @code{continue} command is @code{continue&}, or |
| 4667 | just @code{c&}. The execution commands that accept background execution |
| 4668 | are: |
| 4669 | |
| 4670 | @table @code |
| 4671 | @kindex run& |
| 4672 | @item run |
| 4673 | @xref{Starting, , Starting your Program}. |
| 4674 | |
| 4675 | @item attach |
| 4676 | @kindex attach& |
| 4677 | @xref{Attach, , Debugging an Already-running Process}. |
| 4678 | |
| 4679 | @item step |
| 4680 | @kindex step& |
| 4681 | @xref{Continuing and Stepping, step}. |
| 4682 | |
| 4683 | @item stepi |
| 4684 | @kindex stepi& |
| 4685 | @xref{Continuing and Stepping, stepi}. |
| 4686 | |
| 4687 | @item next |
| 4688 | @kindex next& |
| 4689 | @xref{Continuing and Stepping, next}. |
| 4690 | |
| 4691 | @item nexti |
| 4692 | @kindex nexti& |
| 4693 | @xref{Continuing and Stepping, nexti}. |
| 4694 | |
| 4695 | @item continue |
| 4696 | @kindex continue& |
| 4697 | @xref{Continuing and Stepping, continue}. |
| 4698 | |
| 4699 | @item finish |
| 4700 | @kindex finish& |
| 4701 | @xref{Continuing and Stepping, finish}. |
| 4702 | |
| 4703 | @item until |
| 4704 | @kindex until& |
| 4705 | @xref{Continuing and Stepping, until}. |
| 4706 | |
| 4707 | @end table |
| 4708 | |
| 4709 | Background execution is especially useful in conjunction with non-stop |
| 4710 | mode for debugging programs with multiple threads; see @ref{Non-Stop Mode}. |
| 4711 | However, you can also use these commands in the normal all-stop mode with |
| 4712 | the restriction that you cannot issue another execution command until the |
| 4713 | previous one finishes. Examples of commands that are valid in all-stop |
| 4714 | mode while the program is running include @code{help} and @code{info break}. |
| 4715 | |
| 4716 | You can interrupt your program while it is running in the background by |
| 4717 | using the @code{interrupt} command. |
| 4718 | |
| 4719 | @table @code |
| 4720 | @kindex interrupt |
| 4721 | @item interrupt |
| 4722 | @itemx interrupt -a |
| 4723 | |
| 4724 | Suspend execution of the running program. In all-stop mode, |
| 4725 | @code{interrupt} stops the whole process, but in non-stop mode, it stops |
| 4726 | only the current thread. To stop the whole program in non-stop mode, |
| 4727 | use @code{interrupt -a}. |
| 4728 | @end table |
| 4729 | |
| 4730 | You may need to explicitly enable async mode before you can use background |
| 4731 | execution commands, with the @code{set target-async 1} command. If the |
| 4732 | target doesn't support async mode, @value{GDBN} issues an error message |
| 4733 | if you attempt to use the background execution commands. |
| 4734 | |
| 4735 | @node Thread-Specific Breakpoints |
| 4736 | @subsection Thread-Specific Breakpoints |
| 4737 | |
| 4738 | When your program has multiple threads (@pxref{Threads,, Debugging |
| 4739 | Programs with Multiple Threads}), you can choose whether to set |
| 4740 | breakpoints on all threads, or on a particular thread. |
| 4741 | |
| 4742 | @table @code |
| 4743 | @cindex breakpoints and threads |
| 4744 | @cindex thread breakpoints |
| 4745 | @kindex break @dots{} thread @var{threadno} |
| 4746 | @item break @var{linespec} thread @var{threadno} |
| 4747 | @itemx break @var{linespec} thread @var{threadno} if @dots{} |
| 4748 | @var{linespec} specifies source lines; there are several ways of |
| 4749 | writing them (@pxref{Specify Location}), but the effect is always to |
| 4750 | specify some source line. |
| 4751 | |
| 4752 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command |
| 4753 | to specify that you only want @value{GDBN} to stop the program when a |
| 4754 | particular thread reaches this breakpoint. @var{threadno} is one of the |
| 4755 | numeric thread identifiers assigned by @value{GDBN}, shown in the first |
| 4756 | column of the @samp{info threads} display. |
| 4757 | |
| 4758 | If you do not specify @samp{thread @var{threadno}} when you set a |
| 4759 | breakpoint, the breakpoint applies to @emph{all} threads of your |
| 4760 | program. |
| 4761 | |
| 4762 | You can use the @code{thread} qualifier on conditional breakpoints as |
| 4763 | well; in this case, place @samp{thread @var{threadno}} before the |
| 4764 | breakpoint condition, like this: |
| 4765 | |
| 4766 | @smallexample |
| 4767 | (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim |
| 4768 | @end smallexample |
| 4769 | |
| 4770 | @end table |
| 4771 | |
| 4772 | @node Interrupted System Calls |
| 4773 | @subsection Interrupted System Calls |
| 4774 | |
| 4775 | @cindex thread breakpoints and system calls |
| 4776 | @cindex system calls and thread breakpoints |
| 4777 | @cindex premature return from system calls |
| 4778 | There is an unfortunate side effect when using @value{GDBN} to debug |
| 4779 | multi-threaded programs. If one thread stops for a |
| 4780 | breakpoint, or for some other reason, and another thread is blocked in a |
| 4781 | system call, then the system call may return prematurely. This is a |
| 4782 | consequence of the interaction between multiple threads and the signals |
| 4783 | that @value{GDBN} uses to implement breakpoints and other events that |
| 4784 | stop execution. |
| 4785 | |
| 4786 | To handle this problem, your program should check the return value of |
| 4787 | each system call and react appropriately. This is good programming |
| 4788 | style anyways. |
| 4789 | |
| 4790 | For example, do not write code like this: |
| 4791 | |
| 4792 | @smallexample |
| 4793 | sleep (10); |
| 4794 | @end smallexample |
| 4795 | |
| 4796 | The call to @code{sleep} will return early if a different thread stops |
| 4797 | at a breakpoint or for some other reason. |
| 4798 | |
| 4799 | Instead, write this: |
| 4800 | |
| 4801 | @smallexample |
| 4802 | int unslept = 10; |
| 4803 | while (unslept > 0) |
| 4804 | unslept = sleep (unslept); |
| 4805 | @end smallexample |
| 4806 | |
| 4807 | A system call is allowed to return early, so the system is still |
| 4808 | conforming to its specification. But @value{GDBN} does cause your |
| 4809 | multi-threaded program to behave differently than it would without |
| 4810 | @value{GDBN}. |
| 4811 | |
| 4812 | Also, @value{GDBN} uses internal breakpoints in the thread library to |
| 4813 | monitor certain events such as thread creation and thread destruction. |
| 4814 | When such an event happens, a system call in another thread may return |
| 4815 | prematurely, even though your program does not appear to stop. |
| 4816 | |
| 4817 | |
| 4818 | @node Reverse Execution |
| 4819 | @chapter Running programs backward |
| 4820 | @cindex reverse execution |
| 4821 | @cindex running programs backward |
| 4822 | |
| 4823 | When you are debugging a program, it is not unusual to realize that |
| 4824 | you have gone too far, and some event of interest has already happened. |
| 4825 | If the target environment supports it, @value{GDBN} can allow you to |
| 4826 | ``rewind'' the program by running it backward. |
| 4827 | |
| 4828 | A target environment that supports reverse execution should be able |
| 4829 | to ``undo'' the changes in machine state that have taken place as the |
| 4830 | program was executing normally. Variables, registers etc.@: should |
| 4831 | revert to their previous values. Obviously this requires a great |
| 4832 | deal of sophistication on the part of the target environment; not |
| 4833 | all target environments can support reverse execution. |
| 4834 | |
| 4835 | When a program is executed in reverse, the instructions that |
| 4836 | have most recently been executed are ``un-executed'', in reverse |
| 4837 | order. The program counter runs backward, following the previous |
| 4838 | thread of execution in reverse. As each instruction is ``un-executed'', |
| 4839 | the values of memory and/or registers that were changed by that |
| 4840 | instruction are reverted to their previous states. After executing |
| 4841 | a piece of source code in reverse, all side effects of that code |
| 4842 | should be ``undone'', and all variables should be returned to their |
| 4843 | prior values@footnote{ |
| 4844 | Note that some side effects are easier to undo than others. For instance, |
| 4845 | memory and registers are relatively easy, but device I/O is hard. Some |
| 4846 | targets may be able undo things like device I/O, and some may not. |
| 4847 | |
| 4848 | The contract between @value{GDBN} and the reverse executing target |
| 4849 | requires only that the target do something reasonable when |
| 4850 | @value{GDBN} tells it to execute backwards, and then report the |
| 4851 | results back to @value{GDBN}. Whatever the target reports back to |
| 4852 | @value{GDBN}, @value{GDBN} will report back to the user. @value{GDBN} |
| 4853 | assumes that the memory and registers that the target reports are in a |
| 4854 | consistant state, but @value{GDBN} accepts whatever it is given. |
| 4855 | }. |
| 4856 | |
| 4857 | If you are debugging in a target environment that supports |
| 4858 | reverse execution, @value{GDBN} provides the following commands. |
| 4859 | |
| 4860 | @table @code |
| 4861 | @kindex reverse-continue |
| 4862 | @kindex rc @r{(@code{reverse-continue})} |
| 4863 | @item reverse-continue @r{[}@var{ignore-count}@r{]} |
| 4864 | @itemx rc @r{[}@var{ignore-count}@r{]} |
| 4865 | Beginning at the point where your program last stopped, start executing |
| 4866 | in reverse. Reverse execution will stop for breakpoints and synchronous |
| 4867 | exceptions (signals), just like normal execution. Behavior of |
| 4868 | asynchronous signals depends on the target environment. |
| 4869 | |
| 4870 | @kindex reverse-step |
| 4871 | @kindex rs @r{(@code{step})} |
| 4872 | @item reverse-step @r{[}@var{count}@r{]} |
| 4873 | Run the program backward until control reaches the start of a |
| 4874 | different source line; then stop it, and return control to @value{GDBN}. |
| 4875 | |
| 4876 | Like the @code{step} command, @code{reverse-step} will only stop |
| 4877 | at the beginning of a source line. It ``un-executes'' the previously |
| 4878 | executed source line. If the previous source line included calls to |
| 4879 | debuggable functions, @code{reverse-step} will step (backward) into |
| 4880 | the called function, stopping at the beginning of the @emph{last} |
| 4881 | statement in the called function (typically a return statement). |
| 4882 | |
| 4883 | Also, as with the @code{step} command, if non-debuggable functions are |
| 4884 | called, @code{reverse-step} will run thru them backward without stopping. |
| 4885 | |
| 4886 | @kindex reverse-stepi |
| 4887 | @kindex rsi @r{(@code{reverse-stepi})} |
| 4888 | @item reverse-stepi @r{[}@var{count}@r{]} |
| 4889 | Reverse-execute one machine instruction. Note that the instruction |
| 4890 | to be reverse-executed is @emph{not} the one pointed to by the program |
| 4891 | counter, but the instruction executed prior to that one. For instance, |
| 4892 | if the last instruction was a jump, @code{reverse-stepi} will take you |
| 4893 | back from the destination of the jump to the jump instruction itself. |
| 4894 | |
| 4895 | @kindex reverse-next |
| 4896 | @kindex rn @r{(@code{reverse-next})} |
| 4897 | @item reverse-next @r{[}@var{count}@r{]} |
| 4898 | Run backward to the beginning of the previous line executed in |
| 4899 | the current (innermost) stack frame. If the line contains function |
| 4900 | calls, they will be ``un-executed'' without stopping. Starting from |
| 4901 | the first line of a function, @code{reverse-next} will take you back |
| 4902 | to the caller of that function, @emph{before} the function was called, |
| 4903 | just as the normal @code{next} command would take you from the last |
| 4904 | line of a function back to its return to its caller |
| 4905 | @footnote{Unles the code is too heavily optimized.}. |
| 4906 | |
| 4907 | @kindex reverse-nexti |
| 4908 | @kindex rni @r{(@code{reverse-nexti})} |
| 4909 | @item reverse-nexti @r{[}@var{count}@r{]} |
| 4910 | Like @code{nexti}, @code{reverse-nexti} executes a single instruction |
| 4911 | in reverse, except that called functions are ``un-executed'' atomically. |
| 4912 | That is, if the previously executed instruction was a return from |
| 4913 | another instruction, @code{reverse-nexti} will continue to execute |
| 4914 | in reverse until the call to that function (from the current stack |
| 4915 | frame) is reached. |
| 4916 | |
| 4917 | @kindex reverse-finish |
| 4918 | @item reverse-finish |
| 4919 | Just as the @code{finish} command takes you to the point where the |
| 4920 | current function returns, @code{reverse-finish} takes you to the point |
| 4921 | where it was called. Instead of ending up at the end of the current |
| 4922 | function invocation, you end up at the beginning. |
| 4923 | |
| 4924 | @kindex set exec-direction |
| 4925 | @item set exec-direction |
| 4926 | Set the direction of target execution. |
| 4927 | @itemx set exec-direction reverse |
| 4928 | @cindex execute forward or backward in time |
| 4929 | @value{GDBN} will perform all execution commands in reverse, until the |
| 4930 | exec-direction mode is changed to ``forward''. Affected commands include |
| 4931 | @code{step, stepi, next, nexti, continue, and finish}. The @code{return} |
| 4932 | command cannot be used in reverse mode. |
| 4933 | @item set exec-direction forward |
| 4934 | @value{GDBN} will perform all execution commands in the normal fashion. |
| 4935 | This is the default. |
| 4936 | @end table |
| 4937 | |
| 4938 | |
| 4939 | @node Stack |
| 4940 | @chapter Examining the Stack |
| 4941 | |
| 4942 | When your program has stopped, the first thing you need to know is where it |
| 4943 | stopped and how it got there. |
| 4944 | |
| 4945 | @cindex call stack |
| 4946 | Each time your program performs a function call, information about the call |
| 4947 | is generated. |
| 4948 | That information includes the location of the call in your program, |
| 4949 | the arguments of the call, |
| 4950 | and the local variables of the function being called. |
| 4951 | The information is saved in a block of data called a @dfn{stack frame}. |
| 4952 | The stack frames are allocated in a region of memory called the @dfn{call |
| 4953 | stack}. |
| 4954 | |
| 4955 | When your program stops, the @value{GDBN} commands for examining the |
| 4956 | stack allow you to see all of this information. |
| 4957 | |
| 4958 | @cindex selected frame |
| 4959 | One of the stack frames is @dfn{selected} by @value{GDBN} and many |
| 4960 | @value{GDBN} commands refer implicitly to the selected frame. In |
| 4961 | particular, whenever you ask @value{GDBN} for the value of a variable in |
| 4962 | your program, the value is found in the selected frame. There are |
| 4963 | special @value{GDBN} commands to select whichever frame you are |
| 4964 | interested in. @xref{Selection, ,Selecting a Frame}. |
| 4965 | |
| 4966 | When your program stops, @value{GDBN} automatically selects the |
| 4967 | currently executing frame and describes it briefly, similar to the |
| 4968 | @code{frame} command (@pxref{Frame Info, ,Information about a Frame}). |
| 4969 | |
| 4970 | @menu |
| 4971 | * Frames:: Stack frames |
| 4972 | * Backtrace:: Backtraces |
| 4973 | * Selection:: Selecting a frame |
| 4974 | * Frame Info:: Information on a frame |
| 4975 | |
| 4976 | @end menu |
| 4977 | |
| 4978 | @node Frames |
| 4979 | @section Stack Frames |
| 4980 | |
| 4981 | @cindex frame, definition |
| 4982 | @cindex stack frame |
| 4983 | The call stack is divided up into contiguous pieces called @dfn{stack |
| 4984 | frames}, or @dfn{frames} for short; each frame is the data associated |
| 4985 | with one call to one function. The frame contains the arguments given |
| 4986 | to the function, the function's local variables, and the address at |
| 4987 | which the function is executing. |
| 4988 | |
| 4989 | @cindex initial frame |
| 4990 | @cindex outermost frame |
| 4991 | @cindex innermost frame |
| 4992 | When your program is started, the stack has only one frame, that of the |
| 4993 | function @code{main}. This is called the @dfn{initial} frame or the |
| 4994 | @dfn{outermost} frame. Each time a function is called, a new frame is |
| 4995 | made. Each time a function returns, the frame for that function invocation |
| 4996 | is eliminated. If a function is recursive, there can be many frames for |
| 4997 | the same function. The frame for the function in which execution is |
| 4998 | actually occurring is called the @dfn{innermost} frame. This is the most |
| 4999 | recently created of all the stack frames that still exist. |
| 5000 | |
| 5001 | @cindex frame pointer |
| 5002 | Inside your program, stack frames are identified by their addresses. A |
| 5003 | stack frame consists of many bytes, each of which has its own address; each |
| 5004 | kind of computer has a convention for choosing one byte whose |
| 5005 | address serves as the address of the frame. Usually this address is kept |
| 5006 | in a register called the @dfn{frame pointer register} |
| 5007 | (@pxref{Registers, $fp}) while execution is going on in that frame. |
| 5008 | |
| 5009 | @cindex frame number |
| 5010 | @value{GDBN} assigns numbers to all existing stack frames, starting with |
| 5011 | zero for the innermost frame, one for the frame that called it, |
| 5012 | and so on upward. These numbers do not really exist in your program; |
| 5013 | they are assigned by @value{GDBN} to give you a way of designating stack |
| 5014 | frames in @value{GDBN} commands. |
| 5015 | |
| 5016 | @c The -fomit-frame-pointer below perennially causes hbox overflow |
| 5017 | @c underflow problems. |
| 5018 | @cindex frameless execution |
| 5019 | Some compilers provide a way to compile functions so that they operate |
| 5020 | without stack frames. (For example, the @value{NGCC} option |
| 5021 | @smallexample |
| 5022 | @samp{-fomit-frame-pointer} |
| 5023 | @end smallexample |
| 5024 | generates functions without a frame.) |
| 5025 | This is occasionally done with heavily used library functions to save |
| 5026 | the frame setup time. @value{GDBN} has limited facilities for dealing |
| 5027 | with these function invocations. If the innermost function invocation |
| 5028 | has no stack frame, @value{GDBN} nevertheless regards it as though |
| 5029 | it had a separate frame, which is numbered zero as usual, allowing |
| 5030 | correct tracing of the function call chain. However, @value{GDBN} has |
| 5031 | no provision for frameless functions elsewhere in the stack. |
| 5032 | |
| 5033 | @table @code |
| 5034 | @kindex frame@r{, command} |
| 5035 | @cindex current stack frame |
| 5036 | @item frame @var{args} |
| 5037 | The @code{frame} command allows you to move from one stack frame to another, |
| 5038 | and to print the stack frame you select. @var{args} may be either the |
| 5039 | address of the frame or the stack frame number. Without an argument, |
| 5040 | @code{frame} prints the current stack frame. |
| 5041 | |
| 5042 | @kindex select-frame |
| 5043 | @cindex selecting frame silently |
| 5044 | @item select-frame |
| 5045 | The @code{select-frame} command allows you to move from one stack frame |
| 5046 | to another without printing the frame. This is the silent version of |
| 5047 | @code{frame}. |
| 5048 | @end table |
| 5049 | |
| 5050 | @node Backtrace |
| 5051 | @section Backtraces |
| 5052 | |
| 5053 | @cindex traceback |
| 5054 | @cindex call stack traces |
| 5055 | A backtrace is a summary of how your program got where it is. It shows one |
| 5056 | line per frame, for many frames, starting with the currently executing |
| 5057 | frame (frame zero), followed by its caller (frame one), and on up the |
| 5058 | stack. |
| 5059 | |
| 5060 | @table @code |
| 5061 | @kindex backtrace |
| 5062 | @kindex bt @r{(@code{backtrace})} |
| 5063 | @item backtrace |
| 5064 | @itemx bt |
| 5065 | Print a backtrace of the entire stack: one line per frame for all |
| 5066 | frames in the stack. |
| 5067 | |
| 5068 | You can stop the backtrace at any time by typing the system interrupt |
| 5069 | character, normally @kbd{Ctrl-c}. |
| 5070 | |
| 5071 | @item backtrace @var{n} |
| 5072 | @itemx bt @var{n} |
| 5073 | Similar, but print only the innermost @var{n} frames. |
| 5074 | |
| 5075 | @item backtrace -@var{n} |
| 5076 | @itemx bt -@var{n} |
| 5077 | Similar, but print only the outermost @var{n} frames. |
| 5078 | |
| 5079 | @item backtrace full |
| 5080 | @itemx bt full |
| 5081 | @itemx bt full @var{n} |
| 5082 | @itemx bt full -@var{n} |
| 5083 | Print the values of the local variables also. @var{n} specifies the |
| 5084 | number of frames to print, as described above. |
| 5085 | @end table |
| 5086 | |
| 5087 | @kindex where |
| 5088 | @kindex info stack |
| 5089 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) |
| 5090 | are additional aliases for @code{backtrace}. |
| 5091 | |
| 5092 | @cindex multiple threads, backtrace |
| 5093 | In a multi-threaded program, @value{GDBN} by default shows the |
| 5094 | backtrace only for the current thread. To display the backtrace for |
| 5095 | several or all of the threads, use the command @code{thread apply} |
| 5096 | (@pxref{Threads, thread apply}). For example, if you type @kbd{thread |
| 5097 | apply all backtrace}, @value{GDBN} will display the backtrace for all |
| 5098 | the threads; this is handy when you debug a core dump of a |
| 5099 | multi-threaded program. |
| 5100 | |
| 5101 | Each line in the backtrace shows the frame number and the function name. |
| 5102 | The program counter value is also shown---unless you use @code{set |
| 5103 | print address off}. The backtrace also shows the source file name and |
| 5104 | line number, as well as the arguments to the function. The program |
| 5105 | counter value is omitted if it is at the beginning of the code for that |
| 5106 | line number. |
| 5107 | |
| 5108 | Here is an example of a backtrace. It was made with the command |
| 5109 | @samp{bt 3}, so it shows the innermost three frames. |
| 5110 | |
| 5111 | @smallexample |
| 5112 | @group |
| 5113 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
| 5114 | at builtin.c:993 |
| 5115 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 |
| 5116 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) |
| 5117 | at macro.c:71 |
| 5118 | (More stack frames follow...) |
| 5119 | @end group |
| 5120 | @end smallexample |
| 5121 | |
| 5122 | @noindent |
| 5123 | The display for frame zero does not begin with a program counter |
| 5124 | value, indicating that your program has stopped at the beginning of the |
| 5125 | code for line @code{993} of @code{builtin.c}. |
| 5126 | |
| 5127 | @cindex value optimized out, in backtrace |
| 5128 | @cindex function call arguments, optimized out |
| 5129 | If your program was compiled with optimizations, some compilers will |
| 5130 | optimize away arguments passed to functions if those arguments are |
| 5131 | never used after the call. Such optimizations generate code that |
| 5132 | passes arguments through registers, but doesn't store those arguments |
| 5133 | in the stack frame. @value{GDBN} has no way of displaying such |
| 5134 | arguments in stack frames other than the innermost one. Here's what |
| 5135 | such a backtrace might look like: |
| 5136 | |
| 5137 | @smallexample |
| 5138 | @group |
| 5139 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
| 5140 | at builtin.c:993 |
| 5141 | #1 0x6e38 in expand_macro (sym=<value optimized out>) at macro.c:242 |
| 5142 | #2 0x6840 in expand_token (obs=0x0, t=<value optimized out>, td=0xf7fffb08) |
| 5143 | at macro.c:71 |
| 5144 | (More stack frames follow...) |
| 5145 | @end group |
| 5146 | @end smallexample |
| 5147 | |
| 5148 | @noindent |
| 5149 | The values of arguments that were not saved in their stack frames are |
| 5150 | shown as @samp{<value optimized out>}. |
| 5151 | |
| 5152 | If you need to display the values of such optimized-out arguments, |
| 5153 | either deduce that from other variables whose values depend on the one |
| 5154 | you are interested in, or recompile without optimizations. |
| 5155 | |
| 5156 | @cindex backtrace beyond @code{main} function |
| 5157 | @cindex program entry point |
| 5158 | @cindex startup code, and backtrace |
| 5159 | Most programs have a standard user entry point---a place where system |
| 5160 | libraries and startup code transition into user code. For C this is |
| 5161 | @code{main}@footnote{ |
| 5162 | Note that embedded programs (the so-called ``free-standing'' |
| 5163 | environment) are not required to have a @code{main} function as the |
| 5164 | entry point. They could even have multiple entry points.}. |
| 5165 | When @value{GDBN} finds the entry function in a backtrace |
| 5166 | it will terminate the backtrace, to avoid tracing into highly |
| 5167 | system-specific (and generally uninteresting) code. |
| 5168 | |
| 5169 | If you need to examine the startup code, or limit the number of levels |
| 5170 | in a backtrace, you can change this behavior: |
| 5171 | |
| 5172 | @table @code |
| 5173 | @item set backtrace past-main |
| 5174 | @itemx set backtrace past-main on |
| 5175 | @kindex set backtrace |
| 5176 | Backtraces will continue past the user entry point. |
| 5177 | |
| 5178 | @item set backtrace past-main off |
| 5179 | Backtraces will stop when they encounter the user entry point. This is the |
| 5180 | default. |
| 5181 | |
| 5182 | @item show backtrace past-main |
| 5183 | @kindex show backtrace |
| 5184 | Display the current user entry point backtrace policy. |
| 5185 | |
| 5186 | @item set backtrace past-entry |
| 5187 | @itemx set backtrace past-entry on |
| 5188 | Backtraces will continue past the internal entry point of an application. |
| 5189 | This entry point is encoded by the linker when the application is built, |
| 5190 | and is likely before the user entry point @code{main} (or equivalent) is called. |
| 5191 | |
| 5192 | @item set backtrace past-entry off |
| 5193 | Backtraces will stop when they encounter the internal entry point of an |
| 5194 | application. This is the default. |
| 5195 | |
| 5196 | @item show backtrace past-entry |
| 5197 | Display the current internal entry point backtrace policy. |
| 5198 | |
| 5199 | @item set backtrace limit @var{n} |
| 5200 | @itemx set backtrace limit 0 |
| 5201 | @cindex backtrace limit |
| 5202 | Limit the backtrace to @var{n} levels. A value of zero means |
| 5203 | unlimited. |
| 5204 | |
| 5205 | @item show backtrace limit |
| 5206 | Display the current limit on backtrace levels. |
| 5207 | @end table |
| 5208 | |
| 5209 | @node Selection |
| 5210 | @section Selecting a Frame |
| 5211 | |
| 5212 | Most commands for examining the stack and other data in your program work on |
| 5213 | whichever stack frame is selected at the moment. Here are the commands for |
| 5214 | selecting a stack frame; all of them finish by printing a brief description |
| 5215 | of the stack frame just selected. |
| 5216 | |
| 5217 | @table @code |
| 5218 | @kindex frame@r{, selecting} |
| 5219 | @kindex f @r{(@code{frame})} |
| 5220 | @item frame @var{n} |
| 5221 | @itemx f @var{n} |
| 5222 | Select frame number @var{n}. Recall that frame zero is the innermost |
| 5223 | (currently executing) frame, frame one is the frame that called the |
| 5224 | innermost one, and so on. The highest-numbered frame is the one for |
| 5225 | @code{main}. |
| 5226 | |
| 5227 | @item frame @var{addr} |
| 5228 | @itemx f @var{addr} |
| 5229 | Select the frame at address @var{addr}. This is useful mainly if the |
| 5230 | chaining of stack frames has been damaged by a bug, making it |
| 5231 | impossible for @value{GDBN} to assign numbers properly to all frames. In |
| 5232 | addition, this can be useful when your program has multiple stacks and |
| 5233 | switches between them. |
| 5234 | |
| 5235 | On the SPARC architecture, @code{frame} needs two addresses to |
| 5236 | select an arbitrary frame: a frame pointer and a stack pointer. |
| 5237 | |
| 5238 | On the MIPS and Alpha architecture, it needs two addresses: a stack |
| 5239 | pointer and a program counter. |
| 5240 | |
| 5241 | On the 29k architecture, it needs three addresses: a register stack |
| 5242 | pointer, a program counter, and a memory stack pointer. |
| 5243 | |
| 5244 | @kindex up |
| 5245 | @item up @var{n} |
| 5246 | Move @var{n} frames up the stack. For positive numbers @var{n}, this |
| 5247 | advances toward the outermost frame, to higher frame numbers, to frames |
| 5248 | that have existed longer. @var{n} defaults to one. |
| 5249 | |
| 5250 | @kindex down |
| 5251 | @kindex do @r{(@code{down})} |
| 5252 | @item down @var{n} |
| 5253 | Move @var{n} frames down the stack. For positive numbers @var{n}, this |
| 5254 | advances toward the innermost frame, to lower frame numbers, to frames |
| 5255 | that were created more recently. @var{n} defaults to one. You may |
| 5256 | abbreviate @code{down} as @code{do}. |
| 5257 | @end table |
| 5258 | |
| 5259 | All of these commands end by printing two lines of output describing the |
| 5260 | frame. The first line shows the frame number, the function name, the |
| 5261 | arguments, and the source file and line number of execution in that |
| 5262 | frame. The second line shows the text of that source line. |
| 5263 | |
| 5264 | @need 1000 |
| 5265 | For example: |
| 5266 | |
| 5267 | @smallexample |
| 5268 | @group |
| 5269 | (@value{GDBP}) up |
| 5270 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) |
| 5271 | at env.c:10 |
| 5272 | 10 read_input_file (argv[i]); |
| 5273 | @end group |
| 5274 | @end smallexample |
| 5275 | |
| 5276 | After such a printout, the @code{list} command with no arguments |
| 5277 | prints ten lines centered on the point of execution in the frame. |
| 5278 | You can also edit the program at the point of execution with your favorite |
| 5279 | editing program by typing @code{edit}. |
| 5280 | @xref{List, ,Printing Source Lines}, |
| 5281 | for details. |
| 5282 | |
| 5283 | @table @code |
| 5284 | @kindex down-silently |
| 5285 | @kindex up-silently |
| 5286 | @item up-silently @var{n} |
| 5287 | @itemx down-silently @var{n} |
| 5288 | These two commands are variants of @code{up} and @code{down}, |
| 5289 | respectively; they differ in that they do their work silently, without |
| 5290 | causing display of the new frame. They are intended primarily for use |
| 5291 | in @value{GDBN} command scripts, where the output might be unnecessary and |
| 5292 | distracting. |
| 5293 | @end table |
| 5294 | |
| 5295 | @node Frame Info |
| 5296 | @section Information About a Frame |
| 5297 | |
| 5298 | There are several other commands to print information about the selected |
| 5299 | stack frame. |
| 5300 | |
| 5301 | @table @code |
| 5302 | @item frame |
| 5303 | @itemx f |
| 5304 | When used without any argument, this command does not change which |
| 5305 | frame is selected, but prints a brief description of the currently |
| 5306 | selected stack frame. It can be abbreviated @code{f}. With an |
| 5307 | argument, this command is used to select a stack frame. |
| 5308 | @xref{Selection, ,Selecting a Frame}. |
| 5309 | |
| 5310 | @kindex info frame |
| 5311 | @kindex info f @r{(@code{info frame})} |
| 5312 | @item info frame |
| 5313 | @itemx info f |
| 5314 | This command prints a verbose description of the selected stack frame, |
| 5315 | including: |
| 5316 | |
| 5317 | @itemize @bullet |
| 5318 | @item |
| 5319 | the address of the frame |
| 5320 | @item |
| 5321 | the address of the next frame down (called by this frame) |
| 5322 | @item |
| 5323 | the address of the next frame up (caller of this frame) |
| 5324 | @item |
| 5325 | the language in which the source code corresponding to this frame is written |
| 5326 | @item |
| 5327 | the address of the frame's arguments |
| 5328 | @item |
| 5329 | the address of the frame's local variables |
| 5330 | @item |
| 5331 | the program counter saved in it (the address of execution in the caller frame) |
| 5332 | @item |
| 5333 | which registers were saved in the frame |
| 5334 | @end itemize |
| 5335 | |
| 5336 | @noindent The verbose description is useful when |
| 5337 | something has gone wrong that has made the stack format fail to fit |
| 5338 | the usual conventions. |
| 5339 | |
| 5340 | @item info frame @var{addr} |
| 5341 | @itemx info f @var{addr} |
| 5342 | Print a verbose description of the frame at address @var{addr}, without |
| 5343 | selecting that frame. The selected frame remains unchanged by this |
| 5344 | command. This requires the same kind of address (more than one for some |
| 5345 | architectures) that you specify in the @code{frame} command. |
| 5346 | @xref{Selection, ,Selecting a Frame}. |
| 5347 | |
| 5348 | @kindex info args |
| 5349 | @item info args |
| 5350 | Print the arguments of the selected frame, each on a separate line. |
| 5351 | |
| 5352 | @item info locals |
| 5353 | @kindex info locals |
| 5354 | Print the local variables of the selected frame, each on a separate |
| 5355 | line. These are all variables (declared either static or automatic) |
| 5356 | accessible at the point of execution of the selected frame. |
| 5357 | |
| 5358 | @kindex info catch |
| 5359 | @cindex catch exceptions, list active handlers |
| 5360 | @cindex exception handlers, how to list |
| 5361 | @item info catch |
| 5362 | Print a list of all the exception handlers that are active in the |
| 5363 | current stack frame at the current point of execution. To see other |
| 5364 | exception handlers, visit the associated frame (using the @code{up}, |
| 5365 | @code{down}, or @code{frame} commands); then type @code{info catch}. |
| 5366 | @xref{Set Catchpoints, , Setting Catchpoints}. |
| 5367 | |
| 5368 | @end table |
| 5369 | |
| 5370 | |
| 5371 | @node Source |
| 5372 | @chapter Examining Source Files |
| 5373 | |
| 5374 | @value{GDBN} can print parts of your program's source, since the debugging |
| 5375 | information recorded in the program tells @value{GDBN} what source files were |
| 5376 | used to build it. When your program stops, @value{GDBN} spontaneously prints |
| 5377 | the line where it stopped. Likewise, when you select a stack frame |
| 5378 | (@pxref{Selection, ,Selecting a Frame}), @value{GDBN} prints the line where |
| 5379 | execution in that frame has stopped. You can print other portions of |
| 5380 | source files by explicit command. |
| 5381 | |
| 5382 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may |
| 5383 | prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using |
| 5384 | @value{GDBN} under @sc{gnu} Emacs}. |
| 5385 | |
| 5386 | @menu |
| 5387 | * List:: Printing source lines |
| 5388 | * Specify Location:: How to specify code locations |
| 5389 | * Edit:: Editing source files |
| 5390 | * Search:: Searching source files |
| 5391 | * Source Path:: Specifying source directories |
| 5392 | * Machine Code:: Source and machine code |
| 5393 | @end menu |
| 5394 | |
| 5395 | @node List |
| 5396 | @section Printing Source Lines |
| 5397 | |
| 5398 | @kindex list |
| 5399 | @kindex l @r{(@code{list})} |
| 5400 | To print lines from a source file, use the @code{list} command |
| 5401 | (abbreviated @code{l}). By default, ten lines are printed. |
| 5402 | There are several ways to specify what part of the file you want to |
| 5403 | print; see @ref{Specify Location}, for the full list. |
| 5404 | |
| 5405 | Here are the forms of the @code{list} command most commonly used: |
| 5406 | |
| 5407 | @table @code |
| 5408 | @item list @var{linenum} |
| 5409 | Print lines centered around line number @var{linenum} in the |
| 5410 | current source file. |
| 5411 | |
| 5412 | @item list @var{function} |
| 5413 | Print lines centered around the beginning of function |
| 5414 | @var{function}. |
| 5415 | |
| 5416 | @item list |
| 5417 | Print more lines. If the last lines printed were printed with a |
| 5418 | @code{list} command, this prints lines following the last lines |
| 5419 | printed; however, if the last line printed was a solitary line printed |
| 5420 | as part of displaying a stack frame (@pxref{Stack, ,Examining the |
| 5421 | Stack}), this prints lines centered around that line. |
| 5422 | |
| 5423 | @item list - |
| 5424 | Print lines just before the lines last printed. |
| 5425 | @end table |
| 5426 | |
| 5427 | @cindex @code{list}, how many lines to display |
| 5428 | By default, @value{GDBN} prints ten source lines with any of these forms of |
| 5429 | the @code{list} command. You can change this using @code{set listsize}: |
| 5430 | |
| 5431 | @table @code |
| 5432 | @kindex set listsize |
| 5433 | @item set listsize @var{count} |
| 5434 | Make the @code{list} command display @var{count} source lines (unless |
| 5435 | the @code{list} argument explicitly specifies some other number). |
| 5436 | |
| 5437 | @kindex show listsize |
| 5438 | @item show listsize |
| 5439 | Display the number of lines that @code{list} prints. |
| 5440 | @end table |
| 5441 | |
| 5442 | Repeating a @code{list} command with @key{RET} discards the argument, |
| 5443 | so it is equivalent to typing just @code{list}. This is more useful |
| 5444 | than listing the same lines again. An exception is made for an |
| 5445 | argument of @samp{-}; that argument is preserved in repetition so that |
| 5446 | each repetition moves up in the source file. |
| 5447 | |
| 5448 | In general, the @code{list} command expects you to supply zero, one or two |
| 5449 | @dfn{linespecs}. Linespecs specify source lines; there are several ways |
| 5450 | of writing them (@pxref{Specify Location}), but the effect is always |
| 5451 | to specify some source line. |
| 5452 | |
| 5453 | Here is a complete description of the possible arguments for @code{list}: |
| 5454 | |
| 5455 | @table @code |
| 5456 | @item list @var{linespec} |
| 5457 | Print lines centered around the line specified by @var{linespec}. |
| 5458 | |
| 5459 | @item list @var{first},@var{last} |
| 5460 | Print lines from @var{first} to @var{last}. Both arguments are |
| 5461 | linespecs. When a @code{list} command has two linespecs, and the |
| 5462 | source file of the second linespec is omitted, this refers to |
| 5463 | the same source file as the first linespec. |
| 5464 | |
| 5465 | @item list ,@var{last} |
| 5466 | Print lines ending with @var{last}. |
| 5467 | |
| 5468 | @item list @var{first}, |
| 5469 | Print lines starting with @var{first}. |
| 5470 | |
| 5471 | @item list + |
| 5472 | Print lines just after the lines last printed. |
| 5473 | |
| 5474 | @item list - |
| 5475 | Print lines just before the lines last printed. |
| 5476 | |
| 5477 | @item list |
| 5478 | As described in the preceding table. |
| 5479 | @end table |
| 5480 | |
| 5481 | @node Specify Location |
| 5482 | @section Specifying a Location |
| 5483 | @cindex specifying location |
| 5484 | @cindex linespec |
| 5485 | |
| 5486 | Several @value{GDBN} commands accept arguments that specify a location |
| 5487 | of your program's code. Since @value{GDBN} is a source-level |
| 5488 | debugger, a location usually specifies some line in the source code; |
| 5489 | for that reason, locations are also known as @dfn{linespecs}. |
| 5490 | |
| 5491 | Here are all the different ways of specifying a code location that |
| 5492 | @value{GDBN} understands: |
| 5493 | |
| 5494 | @table @code |
| 5495 | @item @var{linenum} |
| 5496 | Specifies the line number @var{linenum} of the current source file. |
| 5497 | |
| 5498 | @item -@var{offset} |
| 5499 | @itemx +@var{offset} |
| 5500 | Specifies the line @var{offset} lines before or after the @dfn{current |
| 5501 | line}. For the @code{list} command, the current line is the last one |
| 5502 | printed; for the breakpoint commands, this is the line at which |
| 5503 | execution stopped in the currently selected @dfn{stack frame} |
| 5504 | (@pxref{Frames, ,Frames}, for a description of stack frames.) When |
| 5505 | used as the second of the two linespecs in a @code{list} command, |
| 5506 | this specifies the line @var{offset} lines up or down from the first |
| 5507 | linespec. |
| 5508 | |
| 5509 | @item @var{filename}:@var{linenum} |
| 5510 | Specifies the line @var{linenum} in the source file @var{filename}. |
| 5511 | |
| 5512 | @item @var{function} |
| 5513 | Specifies the line that begins the body of the function @var{function}. |
| 5514 | For example, in C, this is the line with the open brace. |
| 5515 | |
| 5516 | @item @var{filename}:@var{function} |
| 5517 | Specifies the line that begins the body of the function @var{function} |
| 5518 | in the file @var{filename}. You only need the file name with a |
| 5519 | function name to avoid ambiguity when there are identically named |
| 5520 | functions in different source files. |
| 5521 | |
| 5522 | @item *@var{address} |
| 5523 | Specifies the program address @var{address}. For line-oriented |
| 5524 | commands, such as @code{list} and @code{edit}, this specifies a source |
| 5525 | line that contains @var{address}. For @code{break} and other |
| 5526 | breakpoint oriented commands, this can be used to set breakpoints in |
| 5527 | parts of your program which do not have debugging information or |
| 5528 | source files. |
| 5529 | |
| 5530 | Here @var{address} may be any expression valid in the current working |
| 5531 | language (@pxref{Languages, working language}) that specifies a code |
| 5532 | address. In addition, as a convenience, @value{GDBN} extends the |
| 5533 | semantics of expressions used in locations to cover the situations |
| 5534 | that frequently happen during debugging. Here are the various forms |
| 5535 | of @var{address}: |
| 5536 | |
| 5537 | @table @code |
| 5538 | @item @var{expression} |
| 5539 | Any expression valid in the current working language. |
| 5540 | |
| 5541 | @item @var{funcaddr} |
| 5542 | An address of a function or procedure derived from its name. In C, |
| 5543 | C@t{++}, Java, Objective-C, Fortran, minimal, and assembly, this is |
| 5544 | simply the function's name @var{function} (and actually a special case |
| 5545 | of a valid expression). In Pascal and Modula-2, this is |
| 5546 | @code{&@var{function}}. In Ada, this is @code{@var{function}'Address} |
| 5547 | (although the Pascal form also works). |
| 5548 | |
| 5549 | This form specifies the address of the function's first instruction, |
| 5550 | before the stack frame and arguments have been set up. |
| 5551 | |
| 5552 | @item '@var{filename}'::@var{funcaddr} |
| 5553 | Like @var{funcaddr} above, but also specifies the name of the source |
| 5554 | file explicitly. This is useful if the name of the function does not |
| 5555 | specify the function unambiguously, e.g., if there are several |
| 5556 | functions with identical names in different source files. |
| 5557 | @end table |
| 5558 | |
| 5559 | @end table |
| 5560 | |
| 5561 | |
| 5562 | @node Edit |
| 5563 | @section Editing Source Files |
| 5564 | @cindex editing source files |
| 5565 | |
| 5566 | @kindex edit |
| 5567 | @kindex e @r{(@code{edit})} |
| 5568 | To edit the lines in a source file, use the @code{edit} command. |
| 5569 | The editing program of your choice |
| 5570 | is invoked with the current line set to |
| 5571 | the active line in the program. |
| 5572 | Alternatively, there are several ways to specify what part of the file you |
| 5573 | want to print if you want to see other parts of the program: |
| 5574 | |
| 5575 | @table @code |
| 5576 | @item edit @var{location} |
| 5577 | Edit the source file specified by @code{location}. Editing starts at |
| 5578 | that @var{location}, e.g., at the specified source line of the |
| 5579 | specified file. @xref{Specify Location}, for all the possible forms |
| 5580 | of the @var{location} argument; here are the forms of the @code{edit} |
| 5581 | command most commonly used: |
| 5582 | |
| 5583 | @table @code |
| 5584 | @item edit @var{number} |
| 5585 | Edit the current source file with @var{number} as the active line number. |
| 5586 | |
| 5587 | @item edit @var{function} |
| 5588 | Edit the file containing @var{function} at the beginning of its definition. |
| 5589 | @end table |
| 5590 | |
| 5591 | @end table |
| 5592 | |
| 5593 | @subsection Choosing your Editor |
| 5594 | You can customize @value{GDBN} to use any editor you want |
| 5595 | @footnote{ |
| 5596 | The only restriction is that your editor (say @code{ex}), recognizes the |
| 5597 | following command-line syntax: |
| 5598 | @smallexample |
| 5599 | ex +@var{number} file |
| 5600 | @end smallexample |
| 5601 | The optional numeric value +@var{number} specifies the number of the line in |
| 5602 | the file where to start editing.}. |
| 5603 | By default, it is @file{@value{EDITOR}}, but you can change this |
| 5604 | by setting the environment variable @code{EDITOR} before using |
| 5605 | @value{GDBN}. For example, to configure @value{GDBN} to use the |
| 5606 | @code{vi} editor, you could use these commands with the @code{sh} shell: |
| 5607 | @smallexample |
| 5608 | EDITOR=/usr/bin/vi |
| 5609 | export EDITOR |
| 5610 | gdb @dots{} |
| 5611 | @end smallexample |
| 5612 | or in the @code{csh} shell, |
| 5613 | @smallexample |
| 5614 | setenv EDITOR /usr/bin/vi |
| 5615 | gdb @dots{} |
| 5616 | @end smallexample |
| 5617 | |
| 5618 | @node Search |
| 5619 | @section Searching Source Files |
| 5620 | @cindex searching source files |
| 5621 | |
| 5622 | There are two commands for searching through the current source file for a |
| 5623 | regular expression. |
| 5624 | |
| 5625 | @table @code |
| 5626 | @kindex search |
| 5627 | @kindex forward-search |
| 5628 | @item forward-search @var{regexp} |
| 5629 | @itemx search @var{regexp} |
| 5630 | The command @samp{forward-search @var{regexp}} checks each line, |
| 5631 | starting with the one following the last line listed, for a match for |
| 5632 | @var{regexp}. It lists the line that is found. You can use the |
| 5633 | synonym @samp{search @var{regexp}} or abbreviate the command name as |
| 5634 | @code{fo}. |
| 5635 | |
| 5636 | @kindex reverse-search |
| 5637 | @item reverse-search @var{regexp} |
| 5638 | The command @samp{reverse-search @var{regexp}} checks each line, starting |
| 5639 | with the one before the last line listed and going backward, for a match |
| 5640 | for @var{regexp}. It lists the line that is found. You can abbreviate |
| 5641 | this command as @code{rev}. |
| 5642 | @end table |
| 5643 | |
| 5644 | @node Source Path |
| 5645 | @section Specifying Source Directories |
| 5646 | |
| 5647 | @cindex source path |
| 5648 | @cindex directories for source files |
| 5649 | Executable programs sometimes do not record the directories of the source |
| 5650 | files from which they were compiled, just the names. Even when they do, |
| 5651 | the directories could be moved between the compilation and your debugging |
| 5652 | session. @value{GDBN} has a list of directories to search for source files; |
| 5653 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, |
| 5654 | it tries all the directories in the list, in the order they are present |
| 5655 | in the list, until it finds a file with the desired name. |
| 5656 | |
| 5657 | For example, suppose an executable references the file |
| 5658 | @file{/usr/src/foo-1.0/lib/foo.c}, and our source path is |
| 5659 | @file{/mnt/cross}. The file is first looked up literally; if this |
| 5660 | fails, @file{/mnt/cross/usr/src/foo-1.0/lib/foo.c} is tried; if this |
| 5661 | fails, @file{/mnt/cross/foo.c} is opened; if this fails, an error |
| 5662 | message is printed. @value{GDBN} does not look up the parts of the |
| 5663 | source file name, such as @file{/mnt/cross/src/foo-1.0/lib/foo.c}. |
| 5664 | Likewise, the subdirectories of the source path are not searched: if |
| 5665 | the source path is @file{/mnt/cross}, and the binary refers to |
| 5666 | @file{foo.c}, @value{GDBN} would not find it under |
| 5667 | @file{/mnt/cross/usr/src/foo-1.0/lib}. |
| 5668 | |
| 5669 | Plain file names, relative file names with leading directories, file |
| 5670 | names containing dots, etc.@: are all treated as described above; for |
| 5671 | instance, if the source path is @file{/mnt/cross}, and the source file |
| 5672 | is recorded as @file{../lib/foo.c}, @value{GDBN} would first try |
| 5673 | @file{../lib/foo.c}, then @file{/mnt/cross/../lib/foo.c}, and after |
| 5674 | that---@file{/mnt/cross/foo.c}. |
| 5675 | |
| 5676 | Note that the executable search path is @emph{not} used to locate the |
| 5677 | source files. |
| 5678 | |
| 5679 | Whenever you reset or rearrange the source path, @value{GDBN} clears out |
| 5680 | any information it has cached about where source files are found and where |
| 5681 | each line is in the file. |
| 5682 | |
| 5683 | @kindex directory |
| 5684 | @kindex dir |
| 5685 | When you start @value{GDBN}, its source path includes only @samp{cdir} |
| 5686 | and @samp{cwd}, in that order. |
| 5687 | To add other directories, use the @code{directory} command. |
| 5688 | |
| 5689 | The search path is used to find both program source files and @value{GDBN} |
| 5690 | script files (read using the @samp{-command} option and @samp{source} command). |
| 5691 | |
| 5692 | In addition to the source path, @value{GDBN} provides a set of commands |
| 5693 | that manage a list of source path substitution rules. A @dfn{substitution |
| 5694 | rule} specifies how to rewrite source directories stored in the program's |
| 5695 | debug information in case the sources were moved to a different |
| 5696 | directory between compilation and debugging. A rule is made of |
| 5697 | two strings, the first specifying what needs to be rewritten in |
| 5698 | the path, and the second specifying how it should be rewritten. |
| 5699 | In @ref{set substitute-path}, we name these two parts @var{from} and |
| 5700 | @var{to} respectively. @value{GDBN} does a simple string replacement |
| 5701 | of @var{from} with @var{to} at the start of the directory part of the |
| 5702 | source file name, and uses that result instead of the original file |
| 5703 | name to look up the sources. |
| 5704 | |
| 5705 | Using the previous example, suppose the @file{foo-1.0} tree has been |
| 5706 | moved from @file{/usr/src} to @file{/mnt/cross}, then you can tell |
| 5707 | @value{GDBN} to replace @file{/usr/src} in all source path names with |
| 5708 | @file{/mnt/cross}. The first lookup will then be |
| 5709 | @file{/mnt/cross/foo-1.0/lib/foo.c} in place of the original location |
| 5710 | of @file{/usr/src/foo-1.0/lib/foo.c}. To define a source path |
| 5711 | substitution rule, use the @code{set substitute-path} command |
| 5712 | (@pxref{set substitute-path}). |
| 5713 | |
| 5714 | To avoid unexpected substitution results, a rule is applied only if the |
| 5715 | @var{from} part of the directory name ends at a directory separator. |
| 5716 | For instance, a rule substituting @file{/usr/source} into |
| 5717 | @file{/mnt/cross} will be applied to @file{/usr/source/foo-1.0} but |
| 5718 | not to @file{/usr/sourceware/foo-2.0}. And because the substitution |
| 5719 | is applied only at the beginning of the directory name, this rule will |
| 5720 | not be applied to @file{/root/usr/source/baz.c} either. |
| 5721 | |
| 5722 | In many cases, you can achieve the same result using the @code{directory} |
| 5723 | command. However, @code{set substitute-path} can be more efficient in |
| 5724 | the case where the sources are organized in a complex tree with multiple |
| 5725 | subdirectories. With the @code{directory} command, you need to add each |
| 5726 | subdirectory of your project. If you moved the entire tree while |
| 5727 | preserving its internal organization, then @code{set substitute-path} |
| 5728 | allows you to direct the debugger to all the sources with one single |
| 5729 | command. |
| 5730 | |
| 5731 | @code{set substitute-path} is also more than just a shortcut command. |
| 5732 | The source path is only used if the file at the original location no |
| 5733 | longer exists. On the other hand, @code{set substitute-path} modifies |
| 5734 | the debugger behavior to look at the rewritten location instead. So, if |
| 5735 | for any reason a source file that is not relevant to your executable is |
| 5736 | located at the original location, a substitution rule is the only |
| 5737 | method available to point @value{GDBN} at the new location. |
| 5738 | |
| 5739 | @table @code |
| 5740 | @item directory @var{dirname} @dots{} |
| 5741 | @item dir @var{dirname} @dots{} |
| 5742 | Add directory @var{dirname} to the front of the source path. Several |
| 5743 | directory names may be given to this command, separated by @samp{:} |
| 5744 | (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as |
| 5745 | part of absolute file names) or |
| 5746 | whitespace. You may specify a directory that is already in the source |
| 5747 | path; this moves it forward, so @value{GDBN} searches it sooner. |
| 5748 | |
| 5749 | @kindex cdir |
| 5750 | @kindex cwd |
| 5751 | @vindex $cdir@r{, convenience variable} |
| 5752 | @vindex $cwd@r{, convenience variable} |
| 5753 | @cindex compilation directory |
| 5754 | @cindex current directory |
| 5755 | @cindex working directory |
| 5756 | @cindex directory, current |
| 5757 | @cindex directory, compilation |
| 5758 | You can use the string @samp{$cdir} to refer to the compilation |
| 5759 | directory (if one is recorded), and @samp{$cwd} to refer to the current |
| 5760 | working directory. @samp{$cwd} is not the same as @samp{.}---the former |
| 5761 | tracks the current working directory as it changes during your @value{GDBN} |
| 5762 | session, while the latter is immediately expanded to the current |
| 5763 | directory at the time you add an entry to the source path. |
| 5764 | |
| 5765 | @item directory |
| 5766 | Reset the source path to its default value (@samp{$cdir:$cwd} on Unix systems). This requires confirmation. |
| 5767 | |
| 5768 | @c RET-repeat for @code{directory} is explicitly disabled, but since |
| 5769 | @c repeating it would be a no-op we do not say that. (thanks to RMS) |
| 5770 | |
| 5771 | @item show directories |
| 5772 | @kindex show directories |
| 5773 | Print the source path: show which directories it contains. |
| 5774 | |
| 5775 | @anchor{set substitute-path} |
| 5776 | @item set substitute-path @var{from} @var{to} |
| 5777 | @kindex set substitute-path |
| 5778 | Define a source path substitution rule, and add it at the end of the |
| 5779 | current list of existing substitution rules. If a rule with the same |
| 5780 | @var{from} was already defined, then the old rule is also deleted. |
| 5781 | |
| 5782 | For example, if the file @file{/foo/bar/baz.c} was moved to |
| 5783 | @file{/mnt/cross/baz.c}, then the command |
| 5784 | |
| 5785 | @smallexample |
| 5786 | (@value{GDBP}) set substitute-path /usr/src /mnt/cross |
| 5787 | @end smallexample |
| 5788 | |
| 5789 | @noindent |
| 5790 | will tell @value{GDBN} to replace @samp{/usr/src} with |
| 5791 | @samp{/mnt/cross}, which will allow @value{GDBN} to find the file |
| 5792 | @file{baz.c} even though it was moved. |
| 5793 | |
| 5794 | In the case when more than one substitution rule have been defined, |
| 5795 | the rules are evaluated one by one in the order where they have been |
| 5796 | defined. The first one matching, if any, is selected to perform |
| 5797 | the substitution. |
| 5798 | |
| 5799 | For instance, if we had entered the following commands: |
| 5800 | |
| 5801 | @smallexample |
| 5802 | (@value{GDBP}) set substitute-path /usr/src/include /mnt/include |
| 5803 | (@value{GDBP}) set substitute-path /usr/src /mnt/src |
| 5804 | @end smallexample |
| 5805 | |
| 5806 | @noindent |
| 5807 | @value{GDBN} would then rewrite @file{/usr/src/include/defs.h} into |
| 5808 | @file{/mnt/include/defs.h} by using the first rule. However, it would |
| 5809 | use the second rule to rewrite @file{/usr/src/lib/foo.c} into |
| 5810 | @file{/mnt/src/lib/foo.c}. |
| 5811 | |
| 5812 | |
| 5813 | @item unset substitute-path [path] |
| 5814 | @kindex unset substitute-path |
| 5815 | If a path is specified, search the current list of substitution rules |
| 5816 | for a rule that would rewrite that path. Delete that rule if found. |
| 5817 | A warning is emitted by the debugger if no rule could be found. |
| 5818 | |
| 5819 | If no path is specified, then all substitution rules are deleted. |
| 5820 | |
| 5821 | @item show substitute-path [path] |
| 5822 | @kindex show substitute-path |
| 5823 | If a path is specified, then print the source path substitution rule |
| 5824 | which would rewrite that path, if any. |
| 5825 | |
| 5826 | If no path is specified, then print all existing source path substitution |
| 5827 | rules. |
| 5828 | |
| 5829 | @end table |
| 5830 | |
| 5831 | If your source path is cluttered with directories that are no longer of |
| 5832 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong |
| 5833 | versions of source. You can correct the situation as follows: |
| 5834 | |
| 5835 | @enumerate |
| 5836 | @item |
| 5837 | Use @code{directory} with no argument to reset the source path to its default value. |
| 5838 | |
| 5839 | @item |
| 5840 | Use @code{directory} with suitable arguments to reinstall the |
| 5841 | directories you want in the source path. You can add all the |
| 5842 | directories in one command. |
| 5843 | @end enumerate |
| 5844 | |
| 5845 | @node Machine Code |
| 5846 | @section Source and Machine Code |
| 5847 | @cindex source line and its code address |
| 5848 | |
| 5849 | You can use the command @code{info line} to map source lines to program |
| 5850 | addresses (and vice versa), and the command @code{disassemble} to display |
| 5851 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs |
| 5852 | mode, the @code{info line} command causes the arrow to point to the |
| 5853 | line specified. Also, @code{info line} prints addresses in symbolic form as |
| 5854 | well as hex. |
| 5855 | |
| 5856 | @table @code |
| 5857 | @kindex info line |
| 5858 | @item info line @var{linespec} |
| 5859 | Print the starting and ending addresses of the compiled code for |
| 5860 | source line @var{linespec}. You can specify source lines in any of |
| 5861 | the ways documented in @ref{Specify Location}. |
| 5862 | @end table |
| 5863 | |
| 5864 | For example, we can use @code{info line} to discover the location of |
| 5865 | the object code for the first line of function |
| 5866 | @code{m4_changequote}: |
| 5867 | |
| 5868 | @c FIXME: I think this example should also show the addresses in |
| 5869 | @c symbolic form, as they usually would be displayed. |
| 5870 | @smallexample |
| 5871 | (@value{GDBP}) info line m4_changequote |
| 5872 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. |
| 5873 | @end smallexample |
| 5874 | |
| 5875 | @noindent |
| 5876 | @cindex code address and its source line |
| 5877 | We can also inquire (using @code{*@var{addr}} as the form for |
| 5878 | @var{linespec}) what source line covers a particular address: |
| 5879 | @smallexample |
| 5880 | (@value{GDBP}) info line *0x63ff |
| 5881 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. |
| 5882 | @end smallexample |
| 5883 | |
| 5884 | @cindex @code{$_} and @code{info line} |
| 5885 | @cindex @code{x} command, default address |
| 5886 | @kindex x@r{(examine), and} info line |
| 5887 | After @code{info line}, the default address for the @code{x} command |
| 5888 | is changed to the starting address of the line, so that @samp{x/i} is |
| 5889 | sufficient to begin examining the machine code (@pxref{Memory, |
| 5890 | ,Examining Memory}). Also, this address is saved as the value of the |
| 5891 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience |
| 5892 | Variables}). |
| 5893 | |
| 5894 | @table @code |
| 5895 | @kindex disassemble |
| 5896 | @cindex assembly instructions |
| 5897 | @cindex instructions, assembly |
| 5898 | @cindex machine instructions |
| 5899 | @cindex listing machine instructions |
| 5900 | @item disassemble |
| 5901 | @itemx disassemble /m |
| 5902 | This specialized command dumps a range of memory as machine |
| 5903 | instructions. It can also print mixed source+disassembly by specifying |
| 5904 | the @code{/m} modifier. |
| 5905 | The default memory range is the function surrounding the |
| 5906 | program counter of the selected frame. A single argument to this |
| 5907 | command is a program counter value; @value{GDBN} dumps the function |
| 5908 | surrounding this value. Two arguments specify a range of addresses |
| 5909 | (first inclusive, second exclusive) to dump. |
| 5910 | @end table |
| 5911 | |
| 5912 | The following example shows the disassembly of a range of addresses of |
| 5913 | HP PA-RISC 2.0 code: |
| 5914 | |
| 5915 | @smallexample |
| 5916 | (@value{GDBP}) disas 0x32c4 0x32e4 |
| 5917 | Dump of assembler code from 0x32c4 to 0x32e4: |
| 5918 | 0x32c4 <main+204>: addil 0,dp |
| 5919 | 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 |
| 5920 | 0x32cc <main+212>: ldil 0x3000,r31 |
| 5921 | 0x32d0 <main+216>: ble 0x3f8(sr4,r31) |
| 5922 | 0x32d4 <main+220>: ldo 0(r31),rp |
| 5923 | 0x32d8 <main+224>: addil -0x800,dp |
| 5924 | 0x32dc <main+228>: ldo 0x588(r1),r26 |
| 5925 | 0x32e0 <main+232>: ldil 0x3000,r31 |
| 5926 | End of assembler dump. |
| 5927 | @end smallexample |
| 5928 | |
| 5929 | Here is an example showing mixed source+assembly for Intel x86: |
| 5930 | |
| 5931 | @smallexample |
| 5932 | (@value{GDBP}) disas /m main |
| 5933 | Dump of assembler code for function main: |
| 5934 | 5 @{ |
| 5935 | 0x08048330 <main+0>: push %ebp |
| 5936 | 0x08048331 <main+1>: mov %esp,%ebp |
| 5937 | 0x08048333 <main+3>: sub $0x8,%esp |
| 5938 | 0x08048336 <main+6>: and $0xfffffff0,%esp |
| 5939 | 0x08048339 <main+9>: sub $0x10,%esp |
| 5940 | |
| 5941 | 6 printf ("Hello.\n"); |
| 5942 | 0x0804833c <main+12>: movl $0x8048440,(%esp) |
| 5943 | 0x08048343 <main+19>: call 0x8048284 <puts@@plt> |
| 5944 | |
| 5945 | 7 return 0; |
| 5946 | 8 @} |
| 5947 | 0x08048348 <main+24>: mov $0x0,%eax |
| 5948 | 0x0804834d <main+29>: leave |
| 5949 | 0x0804834e <main+30>: ret |
| 5950 | |
| 5951 | End of assembler dump. |
| 5952 | @end smallexample |
| 5953 | |
| 5954 | Some architectures have more than one commonly-used set of instruction |
| 5955 | mnemonics or other syntax. |
| 5956 | |
| 5957 | For programs that were dynamically linked and use shared libraries, |
| 5958 | instructions that call functions or branch to locations in the shared |
| 5959 | libraries might show a seemingly bogus location---it's actually a |
| 5960 | location of the relocation table. On some architectures, @value{GDBN} |
| 5961 | might be able to resolve these to actual function names. |
| 5962 | |
| 5963 | @table @code |
| 5964 | @kindex set disassembly-flavor |
| 5965 | @cindex Intel disassembly flavor |
| 5966 | @cindex AT&T disassembly flavor |
| 5967 | @item set disassembly-flavor @var{instruction-set} |
| 5968 | Select the instruction set to use when disassembling the |
| 5969 | program via the @code{disassemble} or @code{x/i} commands. |
| 5970 | |
| 5971 | Currently this command is only defined for the Intel x86 family. You |
| 5972 | can set @var{instruction-set} to either @code{intel} or @code{att}. |
| 5973 | The default is @code{att}, the AT&T flavor used by default by Unix |
| 5974 | assemblers for x86-based targets. |
| 5975 | |
| 5976 | @kindex show disassembly-flavor |
| 5977 | @item show disassembly-flavor |
| 5978 | Show the current setting of the disassembly flavor. |
| 5979 | @end table |
| 5980 | |
| 5981 | |
| 5982 | @node Data |
| 5983 | @chapter Examining Data |
| 5984 | |
| 5985 | @cindex printing data |
| 5986 | @cindex examining data |
| 5987 | @kindex print |
| 5988 | @kindex inspect |
| 5989 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not |
| 5990 | @c document because it is nonstandard... Under Epoch it displays in a |
| 5991 | @c different window or something like that. |
| 5992 | The usual way to examine data in your program is with the @code{print} |
| 5993 | command (abbreviated @code{p}), or its synonym @code{inspect}. It |
| 5994 | evaluates and prints the value of an expression of the language your |
| 5995 | program is written in (@pxref{Languages, ,Using @value{GDBN} with |
| 5996 | Different Languages}). |
| 5997 | |
| 5998 | @table @code |
| 5999 | @item print @var{expr} |
| 6000 | @itemx print /@var{f} @var{expr} |
| 6001 | @var{expr} is an expression (in the source language). By default the |
| 6002 | value of @var{expr} is printed in a format appropriate to its data type; |
| 6003 | you can choose a different format by specifying @samp{/@var{f}}, where |
| 6004 | @var{f} is a letter specifying the format; see @ref{Output Formats,,Output |
| 6005 | Formats}. |
| 6006 | |
| 6007 | @item print |
| 6008 | @itemx print /@var{f} |
| 6009 | @cindex reprint the last value |
| 6010 | If you omit @var{expr}, @value{GDBN} displays the last value again (from the |
| 6011 | @dfn{value history}; @pxref{Value History, ,Value History}). This allows you to |
| 6012 | conveniently inspect the same value in an alternative format. |
| 6013 | @end table |
| 6014 | |
| 6015 | A more low-level way of examining data is with the @code{x} command. |
| 6016 | It examines data in memory at a specified address and prints it in a |
| 6017 | specified format. @xref{Memory, ,Examining Memory}. |
| 6018 | |
| 6019 | If you are interested in information about types, or about how the |
| 6020 | fields of a struct or a class are declared, use the @code{ptype @var{exp}} |
| 6021 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol |
| 6022 | Table}. |
| 6023 | |
| 6024 | @menu |
| 6025 | * Expressions:: Expressions |
| 6026 | * Ambiguous Expressions:: Ambiguous Expressions |
| 6027 | * Variables:: Program variables |
| 6028 | * Arrays:: Artificial arrays |
| 6029 | * Output Formats:: Output formats |
| 6030 | * Memory:: Examining memory |
| 6031 | * Auto Display:: Automatic display |
| 6032 | * Print Settings:: Print settings |
| 6033 | * Value History:: Value history |
| 6034 | * Convenience Vars:: Convenience variables |
| 6035 | * Registers:: Registers |
| 6036 | * Floating Point Hardware:: Floating point hardware |
| 6037 | * Vector Unit:: Vector Unit |
| 6038 | * OS Information:: Auxiliary data provided by operating system |
| 6039 | * Memory Region Attributes:: Memory region attributes |
| 6040 | * Dump/Restore Files:: Copy between memory and a file |
| 6041 | * Core File Generation:: Cause a program dump its core |
| 6042 | * Character Sets:: Debugging programs that use a different |
| 6043 | character set than GDB does |
| 6044 | * Caching Remote Data:: Data caching for remote targets |
| 6045 | * Searching Memory:: Searching memory for a sequence of bytes |
| 6046 | @end menu |
| 6047 | |
| 6048 | @node Expressions |
| 6049 | @section Expressions |
| 6050 | |
| 6051 | @cindex expressions |
| 6052 | @code{print} and many other @value{GDBN} commands accept an expression and |
| 6053 | compute its value. Any kind of constant, variable or operator defined |
| 6054 | by the programming language you are using is valid in an expression in |
| 6055 | @value{GDBN}. This includes conditional expressions, function calls, |
| 6056 | casts, and string constants. It also includes preprocessor macros, if |
| 6057 | you compiled your program to include this information; see |
| 6058 | @ref{Compilation}. |
| 6059 | |
| 6060 | @cindex arrays in expressions |
| 6061 | @value{GDBN} supports array constants in expressions input by |
| 6062 | the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example, |
| 6063 | you can use the command @code{print @{1, 2, 3@}} to create an array |
| 6064 | of three integers. If you pass an array to a function or assign it |
| 6065 | to a program variable, @value{GDBN} copies the array to memory that |
| 6066 | is @code{malloc}ed in the target program. |
| 6067 | |
| 6068 | Because C is so widespread, most of the expressions shown in examples in |
| 6069 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different |
| 6070 | Languages}, for information on how to use expressions in other |
| 6071 | languages. |
| 6072 | |
| 6073 | In this section, we discuss operators that you can use in @value{GDBN} |
| 6074 | expressions regardless of your programming language. |
| 6075 | |
| 6076 | @cindex casts, in expressions |
| 6077 | Casts are supported in all languages, not just in C, because it is so |
| 6078 | useful to cast a number into a pointer in order to examine a structure |
| 6079 | at that address in memory. |
| 6080 | @c FIXME: casts supported---Mod2 true? |
| 6081 | |
| 6082 | @value{GDBN} supports these operators, in addition to those common |
| 6083 | to programming languages: |
| 6084 | |
| 6085 | @table @code |
| 6086 | @item @@ |
| 6087 | @samp{@@} is a binary operator for treating parts of memory as arrays. |
| 6088 | @xref{Arrays, ,Artificial Arrays}, for more information. |
| 6089 | |
| 6090 | @item :: |
| 6091 | @samp{::} allows you to specify a variable in terms of the file or |
| 6092 | function where it is defined. @xref{Variables, ,Program Variables}. |
| 6093 | |
| 6094 | @cindex @{@var{type}@} |
| 6095 | @cindex type casting memory |
| 6096 | @cindex memory, viewing as typed object |
| 6097 | @cindex casts, to view memory |
| 6098 | @item @{@var{type}@} @var{addr} |
| 6099 | Refers to an object of type @var{type} stored at address @var{addr} in |
| 6100 | memory. @var{addr} may be any expression whose value is an integer or |
| 6101 | pointer (but parentheses are required around binary operators, just as in |
| 6102 | a cast). This construct is allowed regardless of what kind of data is |
| 6103 | normally supposed to reside at @var{addr}. |
| 6104 | @end table |
| 6105 | |
| 6106 | @node Ambiguous Expressions |
| 6107 | @section Ambiguous Expressions |
| 6108 | @cindex ambiguous expressions |
| 6109 | |
| 6110 | Expressions can sometimes contain some ambiguous elements. For instance, |
| 6111 | some programming languages (notably Ada, C@t{++} and Objective-C) permit |
| 6112 | a single function name to be defined several times, for application in |
| 6113 | different contexts. This is called @dfn{overloading}. Another example |
| 6114 | involving Ada is generics. A @dfn{generic package} is similar to C@t{++} |
| 6115 | templates and is typically instantiated several times, resulting in |
| 6116 | the same function name being defined in different contexts. |
| 6117 | |
| 6118 | In some cases and depending on the language, it is possible to adjust |
| 6119 | the expression to remove the ambiguity. For instance in C@t{++}, you |
| 6120 | can specify the signature of the function you want to break on, as in |
| 6121 | @kbd{break @var{function}(@var{types})}. In Ada, using the fully |
| 6122 | qualified name of your function often makes the expression unambiguous |
| 6123 | as well. |
| 6124 | |
| 6125 | When an ambiguity that needs to be resolved is detected, the debugger |
| 6126 | has the capability to display a menu of numbered choices for each |
| 6127 | possibility, and then waits for the selection with the prompt @samp{>}. |
| 6128 | The first option is always @samp{[0] cancel}, and typing @kbd{0 @key{RET}} |
| 6129 | aborts the current command. If the command in which the expression was |
| 6130 | used allows more than one choice to be selected, the next option in the |
| 6131 | menu is @samp{[1] all}, and typing @kbd{1 @key{RET}} selects all possible |
| 6132 | choices. |
| 6133 | |
| 6134 | For example, the following session excerpt shows an attempt to set a |
| 6135 | breakpoint at the overloaded symbol @code{String::after}. |
| 6136 | We choose three particular definitions of that function name: |
| 6137 | |
| 6138 | @c FIXME! This is likely to change to show arg type lists, at least |
| 6139 | @smallexample |
| 6140 | @group |
| 6141 | (@value{GDBP}) b String::after |
| 6142 | [0] cancel |
| 6143 | [1] all |
| 6144 | [2] file:String.cc; line number:867 |
| 6145 | [3] file:String.cc; line number:860 |
| 6146 | [4] file:String.cc; line number:875 |
| 6147 | [5] file:String.cc; line number:853 |
| 6148 | [6] file:String.cc; line number:846 |
| 6149 | [7] file:String.cc; line number:735 |
| 6150 | > 2 4 6 |
| 6151 | Breakpoint 1 at 0xb26c: file String.cc, line 867. |
| 6152 | Breakpoint 2 at 0xb344: file String.cc, line 875. |
| 6153 | Breakpoint 3 at 0xafcc: file String.cc, line 846. |
| 6154 | Multiple breakpoints were set. |
| 6155 | Use the "delete" command to delete unwanted |
| 6156 | breakpoints. |
| 6157 | (@value{GDBP}) |
| 6158 | @end group |
| 6159 | @end smallexample |
| 6160 | |
| 6161 | @table @code |
| 6162 | @kindex set multiple-symbols |
| 6163 | @item set multiple-symbols @var{mode} |
| 6164 | @cindex multiple-symbols menu |
| 6165 | |
| 6166 | This option allows you to adjust the debugger behavior when an expression |
| 6167 | is ambiguous. |
| 6168 | |
| 6169 | By default, @var{mode} is set to @code{all}. If the command with which |
| 6170 | the expression is used allows more than one choice, then @value{GDBN} |
| 6171 | automatically selects all possible choices. For instance, inserting |
| 6172 | a breakpoint on a function using an ambiguous name results in a breakpoint |
| 6173 | inserted on each possible match. However, if a unique choice must be made, |
| 6174 | then @value{GDBN} uses the menu to help you disambiguate the expression. |
| 6175 | For instance, printing the address of an overloaded function will result |
| 6176 | in the use of the menu. |
| 6177 | |
| 6178 | When @var{mode} is set to @code{ask}, the debugger always uses the menu |
| 6179 | when an ambiguity is detected. |
| 6180 | |
| 6181 | Finally, when @var{mode} is set to @code{cancel}, the debugger reports |
| 6182 | an error due to the ambiguity and the command is aborted. |
| 6183 | |
| 6184 | @kindex show multiple-symbols |
| 6185 | @item show multiple-symbols |
| 6186 | Show the current value of the @code{multiple-symbols} setting. |
| 6187 | @end table |
| 6188 | |
| 6189 | @node Variables |
| 6190 | @section Program Variables |
| 6191 | |
| 6192 | The most common kind of expression to use is the name of a variable |
| 6193 | in your program. |
| 6194 | |
| 6195 | Variables in expressions are understood in the selected stack frame |
| 6196 | (@pxref{Selection, ,Selecting a Frame}); they must be either: |
| 6197 | |
| 6198 | @itemize @bullet |
| 6199 | @item |
| 6200 | global (or file-static) |
| 6201 | @end itemize |
| 6202 | |
| 6203 | @noindent or |
| 6204 | |
| 6205 | @itemize @bullet |
| 6206 | @item |
| 6207 | visible according to the scope rules of the |
| 6208 | programming language from the point of execution in that frame |
| 6209 | @end itemize |
| 6210 | |
| 6211 | @noindent This means that in the function |
| 6212 | |
| 6213 | @smallexample |
| 6214 | foo (a) |
| 6215 | int a; |
| 6216 | @{ |
| 6217 | bar (a); |
| 6218 | @{ |
| 6219 | int b = test (); |
| 6220 | bar (b); |
| 6221 | @} |
| 6222 | @} |
| 6223 | @end smallexample |
| 6224 | |
| 6225 | @noindent |
| 6226 | you can examine and use the variable @code{a} whenever your program is |
| 6227 | executing within the function @code{foo}, but you can only use or |
| 6228 | examine the variable @code{b} while your program is executing inside |
| 6229 | the block where @code{b} is declared. |
| 6230 | |
| 6231 | @cindex variable name conflict |
| 6232 | There is an exception: you can refer to a variable or function whose |
| 6233 | scope is a single source file even if the current execution point is not |
| 6234 | in this file. But it is possible to have more than one such variable or |
| 6235 | function with the same name (in different source files). If that |
| 6236 | happens, referring to that name has unpredictable effects. If you wish, |
| 6237 | you can specify a static variable in a particular function or file, |
| 6238 | using the colon-colon (@code{::}) notation: |
| 6239 | |
| 6240 | @cindex colon-colon, context for variables/functions |
| 6241 | @ifnotinfo |
| 6242 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? |
| 6243 | @cindex @code{::}, context for variables/functions |
| 6244 | @end ifnotinfo |
| 6245 | @smallexample |
| 6246 | @var{file}::@var{variable} |
| 6247 | @var{function}::@var{variable} |
| 6248 | @end smallexample |
| 6249 | |
| 6250 | @noindent |
| 6251 | Here @var{file} or @var{function} is the name of the context for the |
| 6252 | static @var{variable}. In the case of file names, you can use quotes to |
| 6253 | make sure @value{GDBN} parses the file name as a single word---for example, |
| 6254 | to print a global value of @code{x} defined in @file{f2.c}: |
| 6255 | |
| 6256 | @smallexample |
| 6257 | (@value{GDBP}) p 'f2.c'::x |
| 6258 | @end smallexample |
| 6259 | |
| 6260 | @cindex C@t{++} scope resolution |
| 6261 | This use of @samp{::} is very rarely in conflict with the very similar |
| 6262 | use of the same notation in C@t{++}. @value{GDBN} also supports use of the C@t{++} |
| 6263 | scope resolution operator in @value{GDBN} expressions. |
| 6264 | @c FIXME: Um, so what happens in one of those rare cases where it's in |
| 6265 | @c conflict?? --mew |
| 6266 | |
| 6267 | @cindex wrong values |
| 6268 | @cindex variable values, wrong |
| 6269 | @cindex function entry/exit, wrong values of variables |
| 6270 | @cindex optimized code, wrong values of variables |
| 6271 | @quotation |
| 6272 | @emph{Warning:} Occasionally, a local variable may appear to have the |
| 6273 | wrong value at certain points in a function---just after entry to a new |
| 6274 | scope, and just before exit. |
| 6275 | @end quotation |
| 6276 | You may see this problem when you are stepping by machine instructions. |
| 6277 | This is because, on most machines, it takes more than one instruction to |
| 6278 | set up a stack frame (including local variable definitions); if you are |
| 6279 | stepping by machine instructions, variables may appear to have the wrong |
| 6280 | values until the stack frame is completely built. On exit, it usually |
| 6281 | also takes more than one machine instruction to destroy a stack frame; |
| 6282 | after you begin stepping through that group of instructions, local |
| 6283 | variable definitions may be gone. |
| 6284 | |
| 6285 | This may also happen when the compiler does significant optimizations. |
| 6286 | To be sure of always seeing accurate values, turn off all optimization |
| 6287 | when compiling. |
| 6288 | |
| 6289 | @cindex ``No symbol "foo" in current context'' |
| 6290 | Another possible effect of compiler optimizations is to optimize |
| 6291 | unused variables out of existence, or assign variables to registers (as |
| 6292 | opposed to memory addresses). Depending on the support for such cases |
| 6293 | offered by the debug info format used by the compiler, @value{GDBN} |
| 6294 | might not be able to display values for such local variables. If that |
| 6295 | happens, @value{GDBN} will print a message like this: |
| 6296 | |
| 6297 | @smallexample |
| 6298 | No symbol "foo" in current context. |
| 6299 | @end smallexample |
| 6300 | |
| 6301 | To solve such problems, either recompile without optimizations, or use a |
| 6302 | different debug info format, if the compiler supports several such |
| 6303 | formats. For example, @value{NGCC}, the @sc{gnu} C/C@t{++} compiler, |
| 6304 | usually supports the @option{-gstabs+} option. @option{-gstabs+} |
| 6305 | produces debug info in a format that is superior to formats such as |
| 6306 | COFF. You may be able to use DWARF 2 (@option{-gdwarf-2}), which is also |
| 6307 | an effective form for debug info. @xref{Debugging Options,,Options |
| 6308 | for Debugging Your Program or GCC, gcc.info, Using the @sc{gnu} |
| 6309 | Compiler Collection (GCC)}. |
| 6310 | @xref{C, ,C and C@t{++}}, for more information about debug info formats |
| 6311 | that are best suited to C@t{++} programs. |
| 6312 | |
| 6313 | If you ask to print an object whose contents are unknown to |
| 6314 | @value{GDBN}, e.g., because its data type is not completely specified |
| 6315 | by the debug information, @value{GDBN} will say @samp{<incomplete |
| 6316 | type>}. @xref{Symbols, incomplete type}, for more about this. |
| 6317 | |
| 6318 | Strings are identified as arrays of @code{char} values without specified |
| 6319 | signedness. Arrays of either @code{signed char} or @code{unsigned char} get |
| 6320 | printed as arrays of 1 byte sized integers. @code{-fsigned-char} or |
| 6321 | @code{-funsigned-char} @value{NGCC} options have no effect as @value{GDBN} |
| 6322 | defines literal string type @code{"char"} as @code{char} without a sign. |
| 6323 | For program code |
| 6324 | |
| 6325 | @smallexample |
| 6326 | char var0[] = "A"; |
| 6327 | signed char var1[] = "A"; |
| 6328 | @end smallexample |
| 6329 | |
| 6330 | You get during debugging |
| 6331 | @smallexample |
| 6332 | (gdb) print var0 |
| 6333 | $1 = "A" |
| 6334 | (gdb) print var1 |
| 6335 | $2 = @{65 'A', 0 '\0'@} |
| 6336 | @end smallexample |
| 6337 | |
| 6338 | @node Arrays |
| 6339 | @section Artificial Arrays |
| 6340 | |
| 6341 | @cindex artificial array |
| 6342 | @cindex arrays |
| 6343 | @kindex @@@r{, referencing memory as an array} |
| 6344 | It is often useful to print out several successive objects of the |
| 6345 | same type in memory; a section of an array, or an array of |
| 6346 | dynamically determined size for which only a pointer exists in the |
| 6347 | program. |
| 6348 | |
| 6349 | You can do this by referring to a contiguous span of memory as an |
| 6350 | @dfn{artificial array}, using the binary operator @samp{@@}. The left |
| 6351 | operand of @samp{@@} should be the first element of the desired array |
| 6352 | and be an individual object. The right operand should be the desired length |
| 6353 | of the array. The result is an array value whose elements are all of |
| 6354 | the type of the left argument. The first element is actually the left |
| 6355 | argument; the second element comes from bytes of memory immediately |
| 6356 | following those that hold the first element, and so on. Here is an |
| 6357 | example. If a program says |
| 6358 | |
| 6359 | @smallexample |
| 6360 | int *array = (int *) malloc (len * sizeof (int)); |
| 6361 | @end smallexample |
| 6362 | |
| 6363 | @noindent |
| 6364 | you can print the contents of @code{array} with |
| 6365 | |
| 6366 | @smallexample |
| 6367 | p *array@@len |
| 6368 | @end smallexample |
| 6369 | |
| 6370 | The left operand of @samp{@@} must reside in memory. Array values made |
| 6371 | with @samp{@@} in this way behave just like other arrays in terms of |
| 6372 | subscripting, and are coerced to pointers when used in expressions. |
| 6373 | Artificial arrays most often appear in expressions via the value history |
| 6374 | (@pxref{Value History, ,Value History}), after printing one out. |
| 6375 | |
| 6376 | Another way to create an artificial array is to use a cast. |
| 6377 | This re-interprets a value as if it were an array. |
| 6378 | The value need not be in memory: |
| 6379 | @smallexample |
| 6380 | (@value{GDBP}) p/x (short[2])0x12345678 |
| 6381 | $1 = @{0x1234, 0x5678@} |
| 6382 | @end smallexample |
| 6383 | |
| 6384 | As a convenience, if you leave the array length out (as in |
| 6385 | @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill |
| 6386 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: |
| 6387 | @smallexample |
| 6388 | (@value{GDBP}) p/x (short[])0x12345678 |
| 6389 | $2 = @{0x1234, 0x5678@} |
| 6390 | @end smallexample |
| 6391 | |
| 6392 | Sometimes the artificial array mechanism is not quite enough; in |
| 6393 | moderately complex data structures, the elements of interest may not |
| 6394 | actually be adjacent---for example, if you are interested in the values |
| 6395 | of pointers in an array. One useful work-around in this situation is |
| 6396 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience |
| 6397 | Variables}) as a counter in an expression that prints the first |
| 6398 | interesting value, and then repeat that expression via @key{RET}. For |
| 6399 | instance, suppose you have an array @code{dtab} of pointers to |
| 6400 | structures, and you are interested in the values of a field @code{fv} |
| 6401 | in each structure. Here is an example of what you might type: |
| 6402 | |
| 6403 | @smallexample |
| 6404 | set $i = 0 |
| 6405 | p dtab[$i++]->fv |
| 6406 | @key{RET} |
| 6407 | @key{RET} |
| 6408 | @dots{} |
| 6409 | @end smallexample |
| 6410 | |
| 6411 | @node Output Formats |
| 6412 | @section Output Formats |
| 6413 | |
| 6414 | @cindex formatted output |
| 6415 | @cindex output formats |
| 6416 | By default, @value{GDBN} prints a value according to its data type. Sometimes |
| 6417 | this is not what you want. For example, you might want to print a number |
| 6418 | in hex, or a pointer in decimal. Or you might want to view data in memory |
| 6419 | at a certain address as a character string or as an instruction. To do |
| 6420 | these things, specify an @dfn{output format} when you print a value. |
| 6421 | |
| 6422 | The simplest use of output formats is to say how to print a value |
| 6423 | already computed. This is done by starting the arguments of the |
| 6424 | @code{print} command with a slash and a format letter. The format |
| 6425 | letters supported are: |
| 6426 | |
| 6427 | @table @code |
| 6428 | @item x |
| 6429 | Regard the bits of the value as an integer, and print the integer in |
| 6430 | hexadecimal. |
| 6431 | |
| 6432 | @item d |
| 6433 | Print as integer in signed decimal. |
| 6434 | |
| 6435 | @item u |
| 6436 | Print as integer in unsigned decimal. |
| 6437 | |
| 6438 | @item o |
| 6439 | Print as integer in octal. |
| 6440 | |
| 6441 | @item t |
| 6442 | Print as integer in binary. The letter @samp{t} stands for ``two''. |
| 6443 | @footnote{@samp{b} cannot be used because these format letters are also |
| 6444 | used with the @code{x} command, where @samp{b} stands for ``byte''; |
| 6445 | see @ref{Memory,,Examining Memory}.} |
| 6446 | |
| 6447 | @item a |
| 6448 | @cindex unknown address, locating |
| 6449 | @cindex locate address |
| 6450 | Print as an address, both absolute in hexadecimal and as an offset from |
| 6451 | the nearest preceding symbol. You can use this format used to discover |
| 6452 | where (in what function) an unknown address is located: |
| 6453 | |
| 6454 | @smallexample |
| 6455 | (@value{GDBP}) p/a 0x54320 |
| 6456 | $3 = 0x54320 <_initialize_vx+396> |
| 6457 | @end smallexample |
| 6458 | |
| 6459 | @noindent |
| 6460 | The command @code{info symbol 0x54320} yields similar results. |
| 6461 | @xref{Symbols, info symbol}. |
| 6462 | |
| 6463 | @item c |
| 6464 | Regard as an integer and print it as a character constant. This |
| 6465 | prints both the numerical value and its character representation. The |
| 6466 | character representation is replaced with the octal escape @samp{\nnn} |
| 6467 | for characters outside the 7-bit @sc{ascii} range. |
| 6468 | |
| 6469 | Without this format, @value{GDBN} displays @code{char}, |
| 6470 | @w{@code{unsigned char}}, and @w{@code{signed char}} data as character |
| 6471 | constants. Single-byte members of vectors are displayed as integer |
| 6472 | data. |
| 6473 | |
| 6474 | @item f |
| 6475 | Regard the bits of the value as a floating point number and print |
| 6476 | using typical floating point syntax. |
| 6477 | |
| 6478 | @item s |
| 6479 | @cindex printing strings |
| 6480 | @cindex printing byte arrays |
| 6481 | Regard as a string, if possible. With this format, pointers to single-byte |
| 6482 | data are displayed as null-terminated strings and arrays of single-byte data |
| 6483 | are displayed as fixed-length strings. Other values are displayed in their |
| 6484 | natural types. |
| 6485 | |
| 6486 | Without this format, @value{GDBN} displays pointers to and arrays of |
| 6487 | @code{char}, @w{@code{unsigned char}}, and @w{@code{signed char}} as |
| 6488 | strings. Single-byte members of a vector are displayed as an integer |
| 6489 | array. |
| 6490 | @end table |
| 6491 | |
| 6492 | For example, to print the program counter in hex (@pxref{Registers}), type |
| 6493 | |
| 6494 | @smallexample |
| 6495 | p/x $pc |
| 6496 | @end smallexample |
| 6497 | |
| 6498 | @noindent |
| 6499 | Note that no space is required before the slash; this is because command |
| 6500 | names in @value{GDBN} cannot contain a slash. |
| 6501 | |
| 6502 | To reprint the last value in the value history with a different format, |
| 6503 | you can use the @code{print} command with just a format and no |
| 6504 | expression. For example, @samp{p/x} reprints the last value in hex. |
| 6505 | |
| 6506 | @node Memory |
| 6507 | @section Examining Memory |
| 6508 | |
| 6509 | You can use the command @code{x} (for ``examine'') to examine memory in |
| 6510 | any of several formats, independently of your program's data types. |
| 6511 | |
| 6512 | @cindex examining memory |
| 6513 | @table @code |
| 6514 | @kindex x @r{(examine memory)} |
| 6515 | @item x/@var{nfu} @var{addr} |
| 6516 | @itemx x @var{addr} |
| 6517 | @itemx x |
| 6518 | Use the @code{x} command to examine memory. |
| 6519 | @end table |
| 6520 | |
| 6521 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how |
| 6522 | much memory to display and how to format it; @var{addr} is an |
| 6523 | expression giving the address where you want to start displaying memory. |
| 6524 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. |
| 6525 | Several commands set convenient defaults for @var{addr}. |
| 6526 | |
| 6527 | @table @r |
| 6528 | @item @var{n}, the repeat count |
| 6529 | The repeat count is a decimal integer; the default is 1. It specifies |
| 6530 | how much memory (counting by units @var{u}) to display. |
| 6531 | @c This really is **decimal**; unaffected by 'set radix' as of GDB |
| 6532 | @c 4.1.2. |
| 6533 | |
| 6534 | @item @var{f}, the display format |
| 6535 | The display format is one of the formats used by @code{print} |
| 6536 | (@samp{x}, @samp{d}, @samp{u}, @samp{o}, @samp{t}, @samp{a}, @samp{c}, |
| 6537 | @samp{f}, @samp{s}), and in addition @samp{i} (for machine instructions). |
| 6538 | The default is @samp{x} (hexadecimal) initially. The default changes |
| 6539 | each time you use either @code{x} or @code{print}. |
| 6540 | |
| 6541 | @item @var{u}, the unit size |
| 6542 | The unit size is any of |
| 6543 | |
| 6544 | @table @code |
| 6545 | @item b |
| 6546 | Bytes. |
| 6547 | @item h |
| 6548 | Halfwords (two bytes). |
| 6549 | @item w |
| 6550 | Words (four bytes). This is the initial default. |
| 6551 | @item g |
| 6552 | Giant words (eight bytes). |
| 6553 | @end table |
| 6554 | |
| 6555 | Each time you specify a unit size with @code{x}, that size becomes the |
| 6556 | default unit the next time you use @code{x}. (For the @samp{s} and |
| 6557 | @samp{i} formats, the unit size is ignored and is normally not written.) |
| 6558 | |
| 6559 | @item @var{addr}, starting display address |
| 6560 | @var{addr} is the address where you want @value{GDBN} to begin displaying |
| 6561 | memory. The expression need not have a pointer value (though it may); |
| 6562 | it is always interpreted as an integer address of a byte of memory. |
| 6563 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for |
| 6564 | @var{addr} is usually just after the last address examined---but several |
| 6565 | other commands also set the default address: @code{info breakpoints} (to |
| 6566 | the address of the last breakpoint listed), @code{info line} (to the |
| 6567 | starting address of a line), and @code{print} (if you use it to display |
| 6568 | a value from memory). |
| 6569 | @end table |
| 6570 | |
| 6571 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords |
| 6572 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), |
| 6573 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four |
| 6574 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; |
| 6575 | @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). |
| 6576 | |
| 6577 | Since the letters indicating unit sizes are all distinct from the |
| 6578 | letters specifying output formats, you do not have to remember whether |
| 6579 | unit size or format comes first; either order works. The output |
| 6580 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. |
| 6581 | (However, the count @var{n} must come first; @samp{wx4} does not work.) |
| 6582 | |
| 6583 | Even though the unit size @var{u} is ignored for the formats @samp{s} |
| 6584 | and @samp{i}, you might still want to use a count @var{n}; for example, |
| 6585 | @samp{3i} specifies that you want to see three machine instructions, |
| 6586 | including any operands. For convenience, especially when used with |
| 6587 | the @code{display} command, the @samp{i} format also prints branch delay |
| 6588 | slot instructions, if any, beyond the count specified, which immediately |
| 6589 | follow the last instruction that is within the count. The command |
| 6590 | @code{disassemble} gives an alternative way of inspecting machine |
| 6591 | instructions; see @ref{Machine Code,,Source and Machine Code}. |
| 6592 | |
| 6593 | All the defaults for the arguments to @code{x} are designed to make it |
| 6594 | easy to continue scanning memory with minimal specifications each time |
| 6595 | you use @code{x}. For example, after you have inspected three machine |
| 6596 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven |
| 6597 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, |
| 6598 | the repeat count @var{n} is used again; the other arguments default as |
| 6599 | for successive uses of @code{x}. |
| 6600 | |
| 6601 | @cindex @code{$_}, @code{$__}, and value history |
| 6602 | The addresses and contents printed by the @code{x} command are not saved |
| 6603 | in the value history because there is often too much of them and they |
| 6604 | would get in the way. Instead, @value{GDBN} makes these values available for |
| 6605 | subsequent use in expressions as values of the convenience variables |
| 6606 | @code{$_} and @code{$__}. After an @code{x} command, the last address |
| 6607 | examined is available for use in expressions in the convenience variable |
| 6608 | @code{$_}. The contents of that address, as examined, are available in |
| 6609 | the convenience variable @code{$__}. |
| 6610 | |
| 6611 | If the @code{x} command has a repeat count, the address and contents saved |
| 6612 | are from the last memory unit printed; this is not the same as the last |
| 6613 | address printed if several units were printed on the last line of output. |
| 6614 | |
| 6615 | @cindex remote memory comparison |
| 6616 | @cindex verify remote memory image |
| 6617 | When you are debugging a program running on a remote target machine |
| 6618 | (@pxref{Remote Debugging}), you may wish to verify the program's image in the |
| 6619 | remote machine's memory against the executable file you downloaded to |
| 6620 | the target. The @code{compare-sections} command is provided for such |
| 6621 | situations. |
| 6622 | |
| 6623 | @table @code |
| 6624 | @kindex compare-sections |
| 6625 | @item compare-sections @r{[}@var{section-name}@r{]} |
| 6626 | Compare the data of a loadable section @var{section-name} in the |
| 6627 | executable file of the program being debugged with the same section in |
| 6628 | the remote machine's memory, and report any mismatches. With no |
| 6629 | arguments, compares all loadable sections. This command's |
| 6630 | availability depends on the target's support for the @code{"qCRC"} |
| 6631 | remote request. |
| 6632 | @end table |
| 6633 | |
| 6634 | @node Auto Display |
| 6635 | @section Automatic Display |
| 6636 | @cindex automatic display |
| 6637 | @cindex display of expressions |
| 6638 | |
| 6639 | If you find that you want to print the value of an expression frequently |
| 6640 | (to see how it changes), you might want to add it to the @dfn{automatic |
| 6641 | display list} so that @value{GDBN} prints its value each time your program stops. |
| 6642 | Each expression added to the list is given a number to identify it; |
| 6643 | to remove an expression from the list, you specify that number. |
| 6644 | The automatic display looks like this: |
| 6645 | |
| 6646 | @smallexample |
| 6647 | 2: foo = 38 |
| 6648 | 3: bar[5] = (struct hack *) 0x3804 |
| 6649 | @end smallexample |
| 6650 | |
| 6651 | @noindent |
| 6652 | This display shows item numbers, expressions and their current values. As with |
| 6653 | displays you request manually using @code{x} or @code{print}, you can |
| 6654 | specify the output format you prefer; in fact, @code{display} decides |
| 6655 | whether to use @code{print} or @code{x} depending your format |
| 6656 | specification---it uses @code{x} if you specify either the @samp{i} |
| 6657 | or @samp{s} format, or a unit size; otherwise it uses @code{print}. |
| 6658 | |
| 6659 | @table @code |
| 6660 | @kindex display |
| 6661 | @item display @var{expr} |
| 6662 | Add the expression @var{expr} to the list of expressions to display |
| 6663 | each time your program stops. @xref{Expressions, ,Expressions}. |
| 6664 | |
| 6665 | @code{display} does not repeat if you press @key{RET} again after using it. |
| 6666 | |
| 6667 | @item display/@var{fmt} @var{expr} |
| 6668 | For @var{fmt} specifying only a display format and not a size or |
| 6669 | count, add the expression @var{expr} to the auto-display list but |
| 6670 | arrange to display it each time in the specified format @var{fmt}. |
| 6671 | @xref{Output Formats,,Output Formats}. |
| 6672 | |
| 6673 | @item display/@var{fmt} @var{addr} |
| 6674 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a |
| 6675 | number of units, add the expression @var{addr} as a memory address to |
| 6676 | be examined each time your program stops. Examining means in effect |
| 6677 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining Memory}. |
| 6678 | @end table |
| 6679 | |
| 6680 | For example, @samp{display/i $pc} can be helpful, to see the machine |
| 6681 | instruction about to be executed each time execution stops (@samp{$pc} |
| 6682 | is a common name for the program counter; @pxref{Registers, ,Registers}). |
| 6683 | |
| 6684 | @table @code |
| 6685 | @kindex delete display |
| 6686 | @kindex undisplay |
| 6687 | @item undisplay @var{dnums}@dots{} |
| 6688 | @itemx delete display @var{dnums}@dots{} |
| 6689 | Remove item numbers @var{dnums} from the list of expressions to display. |
| 6690 | |
| 6691 | @code{undisplay} does not repeat if you press @key{RET} after using it. |
| 6692 | (Otherwise you would just get the error @samp{No display number @dots{}}.) |
| 6693 | |
| 6694 | @kindex disable display |
| 6695 | @item disable display @var{dnums}@dots{} |
| 6696 | Disable the display of item numbers @var{dnums}. A disabled display |
| 6697 | item is not printed automatically, but is not forgotten. It may be |
| 6698 | enabled again later. |
| 6699 | |
| 6700 | @kindex enable display |
| 6701 | @item enable display @var{dnums}@dots{} |
| 6702 | Enable display of item numbers @var{dnums}. It becomes effective once |
| 6703 | again in auto display of its expression, until you specify otherwise. |
| 6704 | |
| 6705 | @item display |
| 6706 | Display the current values of the expressions on the list, just as is |
| 6707 | done when your program stops. |
| 6708 | |
| 6709 | @kindex info display |
| 6710 | @item info display |
| 6711 | Print the list of expressions previously set up to display |
| 6712 | automatically, each one with its item number, but without showing the |
| 6713 | values. This includes disabled expressions, which are marked as such. |
| 6714 | It also includes expressions which would not be displayed right now |
| 6715 | because they refer to automatic variables not currently available. |
| 6716 | @end table |
| 6717 | |
| 6718 | @cindex display disabled out of scope |
| 6719 | If a display expression refers to local variables, then it does not make |
| 6720 | sense outside the lexical context for which it was set up. Such an |
| 6721 | expression is disabled when execution enters a context where one of its |
| 6722 | variables is not defined. For example, if you give the command |
| 6723 | @code{display last_char} while inside a function with an argument |
| 6724 | @code{last_char}, @value{GDBN} displays this argument while your program |
| 6725 | continues to stop inside that function. When it stops elsewhere---where |
| 6726 | there is no variable @code{last_char}---the display is disabled |
| 6727 | automatically. The next time your program stops where @code{last_char} |
| 6728 | is meaningful, you can enable the display expression once again. |
| 6729 | |
| 6730 | @node Print Settings |
| 6731 | @section Print Settings |
| 6732 | |
| 6733 | @cindex format options |
| 6734 | @cindex print settings |
| 6735 | @value{GDBN} provides the following ways to control how arrays, structures, |
| 6736 | and symbols are printed. |
| 6737 | |
| 6738 | @noindent |
| 6739 | These settings are useful for debugging programs in any language: |
| 6740 | |
| 6741 | @table @code |
| 6742 | @kindex set print |
| 6743 | @item set print address |
| 6744 | @itemx set print address on |
| 6745 | @cindex print/don't print memory addresses |
| 6746 | @value{GDBN} prints memory addresses showing the location of stack |
| 6747 | traces, structure values, pointer values, breakpoints, and so forth, |
| 6748 | even when it also displays the contents of those addresses. The default |
| 6749 | is @code{on}. For example, this is what a stack frame display looks like with |
| 6750 | @code{set print address on}: |
| 6751 | |
| 6752 | @smallexample |
| 6753 | @group |
| 6754 | (@value{GDBP}) f |
| 6755 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") |
| 6756 | at input.c:530 |
| 6757 | 530 if (lquote != def_lquote) |
| 6758 | @end group |
| 6759 | @end smallexample |
| 6760 | |
| 6761 | @item set print address off |
| 6762 | Do not print addresses when displaying their contents. For example, |
| 6763 | this is the same stack frame displayed with @code{set print address off}: |
| 6764 | |
| 6765 | @smallexample |
| 6766 | @group |
| 6767 | (@value{GDBP}) set print addr off |
| 6768 | (@value{GDBP}) f |
| 6769 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 |
| 6770 | 530 if (lquote != def_lquote) |
| 6771 | @end group |
| 6772 | @end smallexample |
| 6773 | |
| 6774 | You can use @samp{set print address off} to eliminate all machine |
| 6775 | dependent displays from the @value{GDBN} interface. For example, with |
| 6776 | @code{print address off}, you should get the same text for backtraces on |
| 6777 | all machines---whether or not they involve pointer arguments. |
| 6778 | |
| 6779 | @kindex show print |
| 6780 | @item show print address |
| 6781 | Show whether or not addresses are to be printed. |
| 6782 | @end table |
| 6783 | |
| 6784 | When @value{GDBN} prints a symbolic address, it normally prints the |
| 6785 | closest earlier symbol plus an offset. If that symbol does not uniquely |
| 6786 | identify the address (for example, it is a name whose scope is a single |
| 6787 | source file), you may need to clarify. One way to do this is with |
| 6788 | @code{info line}, for example @samp{info line *0x4537}. Alternately, |
| 6789 | you can set @value{GDBN} to print the source file and line number when |
| 6790 | it prints a symbolic address: |
| 6791 | |
| 6792 | @table @code |
| 6793 | @item set print symbol-filename on |
| 6794 | @cindex source file and line of a symbol |
| 6795 | @cindex symbol, source file and line |
| 6796 | Tell @value{GDBN} to print the source file name and line number of a |
| 6797 | symbol in the symbolic form of an address. |
| 6798 | |
| 6799 | @item set print symbol-filename off |
| 6800 | Do not print source file name and line number of a symbol. This is the |
| 6801 | default. |
| 6802 | |
| 6803 | @item show print symbol-filename |
| 6804 | Show whether or not @value{GDBN} will print the source file name and |
| 6805 | line number of a symbol in the symbolic form of an address. |
| 6806 | @end table |
| 6807 | |
| 6808 | Another situation where it is helpful to show symbol filenames and line |
| 6809 | numbers is when disassembling code; @value{GDBN} shows you the line |
| 6810 | number and source file that corresponds to each instruction. |
| 6811 | |
| 6812 | Also, you may wish to see the symbolic form only if the address being |
| 6813 | printed is reasonably close to the closest earlier symbol: |
| 6814 | |
| 6815 | @table @code |
| 6816 | @item set print max-symbolic-offset @var{max-offset} |
| 6817 | @cindex maximum value for offset of closest symbol |
| 6818 | Tell @value{GDBN} to only display the symbolic form of an address if the |
| 6819 | offset between the closest earlier symbol and the address is less than |
| 6820 | @var{max-offset}. The default is 0, which tells @value{GDBN} |
| 6821 | to always print the symbolic form of an address if any symbol precedes it. |
| 6822 | |
| 6823 | @item show print max-symbolic-offset |
| 6824 | Ask how large the maximum offset is that @value{GDBN} prints in a |
| 6825 | symbolic address. |
| 6826 | @end table |
| 6827 | |
| 6828 | @cindex wild pointer, interpreting |
| 6829 | @cindex pointer, finding referent |
| 6830 | If you have a pointer and you are not sure where it points, try |
| 6831 | @samp{set print symbol-filename on}. Then you can determine the name |
| 6832 | and source file location of the variable where it points, using |
| 6833 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. |
| 6834 | For example, here @value{GDBN} shows that a variable @code{ptt} points |
| 6835 | at another variable @code{t}, defined in @file{hi2.c}: |
| 6836 | |
| 6837 | @smallexample |
| 6838 | (@value{GDBP}) set print symbol-filename on |
| 6839 | (@value{GDBP}) p/a ptt |
| 6840 | $4 = 0xe008 <t in hi2.c> |
| 6841 | @end smallexample |
| 6842 | |
| 6843 | @quotation |
| 6844 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} |
| 6845 | does not show the symbol name and filename of the referent, even with |
| 6846 | the appropriate @code{set print} options turned on. |
| 6847 | @end quotation |
| 6848 | |
| 6849 | Other settings control how different kinds of objects are printed: |
| 6850 | |
| 6851 | @table @code |
| 6852 | @item set print array |
| 6853 | @itemx set print array on |
| 6854 | @cindex pretty print arrays |
| 6855 | Pretty print arrays. This format is more convenient to read, |
| 6856 | but uses more space. The default is off. |
| 6857 | |
| 6858 | @item set print array off |
| 6859 | Return to compressed format for arrays. |
| 6860 | |
| 6861 | @item show print array |
| 6862 | Show whether compressed or pretty format is selected for displaying |
| 6863 | arrays. |
| 6864 | |
| 6865 | @cindex print array indexes |
| 6866 | @item set print array-indexes |
| 6867 | @itemx set print array-indexes on |
| 6868 | Print the index of each element when displaying arrays. May be more |
| 6869 | convenient to locate a given element in the array or quickly find the |
| 6870 | index of a given element in that printed array. The default is off. |
| 6871 | |
| 6872 | @item set print array-indexes off |
| 6873 | Stop printing element indexes when displaying arrays. |
| 6874 | |
| 6875 | @item show print array-indexes |
| 6876 | Show whether the index of each element is printed when displaying |
| 6877 | arrays. |
| 6878 | |
| 6879 | @item set print elements @var{number-of-elements} |
| 6880 | @cindex number of array elements to print |
| 6881 | @cindex limit on number of printed array elements |
| 6882 | Set a limit on how many elements of an array @value{GDBN} will print. |
| 6883 | If @value{GDBN} is printing a large array, it stops printing after it has |
| 6884 | printed the number of elements set by the @code{set print elements} command. |
| 6885 | This limit also applies to the display of strings. |
| 6886 | When @value{GDBN} starts, this limit is set to 200. |
| 6887 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
| 6888 | |
| 6889 | @item show print elements |
| 6890 | Display the number of elements of a large array that @value{GDBN} will print. |
| 6891 | If the number is 0, then the printing is unlimited. |
| 6892 | |
| 6893 | @item set print frame-arguments @var{value} |
| 6894 | @cindex printing frame argument values |
| 6895 | @cindex print all frame argument values |
| 6896 | @cindex print frame argument values for scalars only |
| 6897 | @cindex do not print frame argument values |
| 6898 | This command allows to control how the values of arguments are printed |
| 6899 | when the debugger prints a frame (@pxref{Frames}). The possible |
| 6900 | values are: |
| 6901 | |
| 6902 | @table @code |
| 6903 | @item all |
| 6904 | The values of all arguments are printed. This is the default. |
| 6905 | |
| 6906 | @item scalars |
| 6907 | Print the value of an argument only if it is a scalar. The value of more |
| 6908 | complex arguments such as arrays, structures, unions, etc, is replaced |
| 6909 | by @code{@dots{}}. Here is an example where only scalar arguments are shown: |
| 6910 | |
| 6911 | @smallexample |
| 6912 | #1 0x08048361 in call_me (i=3, s=@dots{}, ss=0xbf8d508c, u=@dots{}, e=green) |
| 6913 | at frame-args.c:23 |
| 6914 | @end smallexample |
| 6915 | |
| 6916 | @item none |
| 6917 | None of the argument values are printed. Instead, the value of each argument |
| 6918 | is replaced by @code{@dots{}}. In this case, the example above now becomes: |
| 6919 | |
| 6920 | @smallexample |
| 6921 | #1 0x08048361 in call_me (i=@dots{}, s=@dots{}, ss=@dots{}, u=@dots{}, e=@dots{}) |
| 6922 | at frame-args.c:23 |
| 6923 | @end smallexample |
| 6924 | @end table |
| 6925 | |
| 6926 | By default, all argument values are always printed. But this command |
| 6927 | can be useful in several cases. For instance, it can be used to reduce |
| 6928 | the amount of information printed in each frame, making the backtrace |
| 6929 | more readable. Also, this command can be used to improve performance |
| 6930 | when displaying Ada frames, because the computation of large arguments |
| 6931 | can sometimes be CPU-intensive, especiallly in large applications. |
| 6932 | Setting @code{print frame-arguments} to @code{scalars} or @code{none} |
| 6933 | avoids this computation, thus speeding up the display of each Ada frame. |
| 6934 | |
| 6935 | @item show print frame-arguments |
| 6936 | Show how the value of arguments should be displayed when printing a frame. |
| 6937 | |
| 6938 | @item set print repeats |
| 6939 | @cindex repeated array elements |
| 6940 | Set the threshold for suppressing display of repeated array |
| 6941 | elements. When the number of consecutive identical elements of an |
| 6942 | array exceeds the threshold, @value{GDBN} prints the string |
| 6943 | @code{"<repeats @var{n} times>"}, where @var{n} is the number of |
| 6944 | identical repetitions, instead of displaying the identical elements |
| 6945 | themselves. Setting the threshold to zero will cause all elements to |
| 6946 | be individually printed. The default threshold is 10. |
| 6947 | |
| 6948 | @item show print repeats |
| 6949 | Display the current threshold for printing repeated identical |
| 6950 | elements. |
| 6951 | |
| 6952 | @item set print null-stop |
| 6953 | @cindex @sc{null} elements in arrays |
| 6954 | Cause @value{GDBN} to stop printing the characters of an array when the first |
| 6955 | @sc{null} is encountered. This is useful when large arrays actually |
| 6956 | contain only short strings. |
| 6957 | The default is off. |
| 6958 | |
| 6959 | @item show print null-stop |
| 6960 | Show whether @value{GDBN} stops printing an array on the first |
| 6961 | @sc{null} character. |
| 6962 | |
| 6963 | @item set print pretty on |
| 6964 | @cindex print structures in indented form |
| 6965 | @cindex indentation in structure display |
| 6966 | Cause @value{GDBN} to print structures in an indented format with one member |
| 6967 | per line, like this: |
| 6968 | |
| 6969 | @smallexample |
| 6970 | @group |
| 6971 | $1 = @{ |
| 6972 | next = 0x0, |
| 6973 | flags = @{ |
| 6974 | sweet = 1, |
| 6975 | sour = 1 |
| 6976 | @}, |
| 6977 | meat = 0x54 "Pork" |
| 6978 | @} |
| 6979 | @end group |
| 6980 | @end smallexample |
| 6981 | |
| 6982 | @item set print pretty off |
| 6983 | Cause @value{GDBN} to print structures in a compact format, like this: |
| 6984 | |
| 6985 | @smallexample |
| 6986 | @group |
| 6987 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ |
| 6988 | meat = 0x54 "Pork"@} |
| 6989 | @end group |
| 6990 | @end smallexample |
| 6991 | |
| 6992 | @noindent |
| 6993 | This is the default format. |
| 6994 | |
| 6995 | @item show print pretty |
| 6996 | Show which format @value{GDBN} is using to print structures. |
| 6997 | |
| 6998 | @item set print sevenbit-strings on |
| 6999 | @cindex eight-bit characters in strings |
| 7000 | @cindex octal escapes in strings |
| 7001 | Print using only seven-bit characters; if this option is set, |
| 7002 | @value{GDBN} displays any eight-bit characters (in strings or |
| 7003 | character values) using the notation @code{\}@var{nnn}. This setting is |
| 7004 | best if you are working in English (@sc{ascii}) and you use the |
| 7005 | high-order bit of characters as a marker or ``meta'' bit. |
| 7006 | |
| 7007 | @item set print sevenbit-strings off |
| 7008 | Print full eight-bit characters. This allows the use of more |
| 7009 | international character sets, and is the default. |
| 7010 | |
| 7011 | @item show print sevenbit-strings |
| 7012 | Show whether or not @value{GDBN} is printing only seven-bit characters. |
| 7013 | |
| 7014 | @item set print union on |
| 7015 | @cindex unions in structures, printing |
| 7016 | Tell @value{GDBN} to print unions which are contained in structures |
| 7017 | and other unions. This is the default setting. |
| 7018 | |
| 7019 | @item set print union off |
| 7020 | Tell @value{GDBN} not to print unions which are contained in |
| 7021 | structures and other unions. @value{GDBN} will print @code{"@{...@}"} |
| 7022 | instead. |
| 7023 | |
| 7024 | @item show print union |
| 7025 | Ask @value{GDBN} whether or not it will print unions which are contained in |
| 7026 | structures and other unions. |
| 7027 | |
| 7028 | For example, given the declarations |
| 7029 | |
| 7030 | @smallexample |
| 7031 | typedef enum @{Tree, Bug@} Species; |
| 7032 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; |
| 7033 | typedef enum @{Caterpillar, Cocoon, Butterfly@} |
| 7034 | Bug_forms; |
| 7035 | |
| 7036 | struct thing @{ |
| 7037 | Species it; |
| 7038 | union @{ |
| 7039 | Tree_forms tree; |
| 7040 | Bug_forms bug; |
| 7041 | @} form; |
| 7042 | @}; |
| 7043 | |
| 7044 | struct thing foo = @{Tree, @{Acorn@}@}; |
| 7045 | @end smallexample |
| 7046 | |
| 7047 | @noindent |
| 7048 | with @code{set print union on} in effect @samp{p foo} would print |
| 7049 | |
| 7050 | @smallexample |
| 7051 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} |
| 7052 | @end smallexample |
| 7053 | |
| 7054 | @noindent |
| 7055 | and with @code{set print union off} in effect it would print |
| 7056 | |
| 7057 | @smallexample |
| 7058 | $1 = @{it = Tree, form = @{...@}@} |
| 7059 | @end smallexample |
| 7060 | |
| 7061 | @noindent |
| 7062 | @code{set print union} affects programs written in C-like languages |
| 7063 | and in Pascal. |
| 7064 | @end table |
| 7065 | |
| 7066 | @need 1000 |
| 7067 | @noindent |
| 7068 | These settings are of interest when debugging C@t{++} programs: |
| 7069 | |
| 7070 | @table @code |
| 7071 | @cindex demangling C@t{++} names |
| 7072 | @item set print demangle |
| 7073 | @itemx set print demangle on |
| 7074 | Print C@t{++} names in their source form rather than in the encoded |
| 7075 | (``mangled'') form passed to the assembler and linker for type-safe |
| 7076 | linkage. The default is on. |
| 7077 | |
| 7078 | @item show print demangle |
| 7079 | Show whether C@t{++} names are printed in mangled or demangled form. |
| 7080 | |
| 7081 | @item set print asm-demangle |
| 7082 | @itemx set print asm-demangle on |
| 7083 | Print C@t{++} names in their source form rather than their mangled form, even |
| 7084 | in assembler code printouts such as instruction disassemblies. |
| 7085 | The default is off. |
| 7086 | |
| 7087 | @item show print asm-demangle |
| 7088 | Show whether C@t{++} names in assembly listings are printed in mangled |
| 7089 | or demangled form. |
| 7090 | |
| 7091 | @cindex C@t{++} symbol decoding style |
| 7092 | @cindex symbol decoding style, C@t{++} |
| 7093 | @kindex set demangle-style |
| 7094 | @item set demangle-style @var{style} |
| 7095 | Choose among several encoding schemes used by different compilers to |
| 7096 | represent C@t{++} names. The choices for @var{style} are currently: |
| 7097 | |
| 7098 | @table @code |
| 7099 | @item auto |
| 7100 | Allow @value{GDBN} to choose a decoding style by inspecting your program. |
| 7101 | |
| 7102 | @item gnu |
| 7103 | Decode based on the @sc{gnu} C@t{++} compiler (@code{g++}) encoding algorithm. |
| 7104 | This is the default. |
| 7105 | |
| 7106 | @item hp |
| 7107 | Decode based on the HP ANSI C@t{++} (@code{aCC}) encoding algorithm. |
| 7108 | |
| 7109 | @item lucid |
| 7110 | Decode based on the Lucid C@t{++} compiler (@code{lcc}) encoding algorithm. |
| 7111 | |
| 7112 | @item arm |
| 7113 | Decode using the algorithm in the @cite{C@t{++} Annotated Reference Manual}. |
| 7114 | @strong{Warning:} this setting alone is not sufficient to allow |
| 7115 | debugging @code{cfront}-generated executables. @value{GDBN} would |
| 7116 | require further enhancement to permit that. |
| 7117 | |
| 7118 | @end table |
| 7119 | If you omit @var{style}, you will see a list of possible formats. |
| 7120 | |
| 7121 | @item show demangle-style |
| 7122 | Display the encoding style currently in use for decoding C@t{++} symbols. |
| 7123 | |
| 7124 | @item set print object |
| 7125 | @itemx set print object on |
| 7126 | @cindex derived type of an object, printing |
| 7127 | @cindex display derived types |
| 7128 | When displaying a pointer to an object, identify the @emph{actual} |
| 7129 | (derived) type of the object rather than the @emph{declared} type, using |
| 7130 | the virtual function table. |
| 7131 | |
| 7132 | @item set print object off |
| 7133 | Display only the declared type of objects, without reference to the |
| 7134 | virtual function table. This is the default setting. |
| 7135 | |
| 7136 | @item show print object |
| 7137 | Show whether actual, or declared, object types are displayed. |
| 7138 | |
| 7139 | @item set print static-members |
| 7140 | @itemx set print static-members on |
| 7141 | @cindex static members of C@t{++} objects |
| 7142 | Print static members when displaying a C@t{++} object. The default is on. |
| 7143 | |
| 7144 | @item set print static-members off |
| 7145 | Do not print static members when displaying a C@t{++} object. |
| 7146 | |
| 7147 | @item show print static-members |
| 7148 | Show whether C@t{++} static members are printed or not. |
| 7149 | |
| 7150 | @item set print pascal_static-members |
| 7151 | @itemx set print pascal_static-members on |
| 7152 | @cindex static members of Pascal objects |
| 7153 | @cindex Pascal objects, static members display |
| 7154 | Print static members when displaying a Pascal object. The default is on. |
| 7155 | |
| 7156 | @item set print pascal_static-members off |
| 7157 | Do not print static members when displaying a Pascal object. |
| 7158 | |
| 7159 | @item show print pascal_static-members |
| 7160 | Show whether Pascal static members are printed or not. |
| 7161 | |
| 7162 | @c These don't work with HP ANSI C++ yet. |
| 7163 | @item set print vtbl |
| 7164 | @itemx set print vtbl on |
| 7165 | @cindex pretty print C@t{++} virtual function tables |
| 7166 | @cindex virtual functions (C@t{++}) display |
| 7167 | @cindex VTBL display |
| 7168 | Pretty print C@t{++} virtual function tables. The default is off. |
| 7169 | (The @code{vtbl} commands do not work on programs compiled with the HP |
| 7170 | ANSI C@t{++} compiler (@code{aCC}).) |
| 7171 | |
| 7172 | @item set print vtbl off |
| 7173 | Do not pretty print C@t{++} virtual function tables. |
| 7174 | |
| 7175 | @item show print vtbl |
| 7176 | Show whether C@t{++} virtual function tables are pretty printed, or not. |
| 7177 | @end table |
| 7178 | |
| 7179 | @node Value History |
| 7180 | @section Value History |
| 7181 | |
| 7182 | @cindex value history |
| 7183 | @cindex history of values printed by @value{GDBN} |
| 7184 | Values printed by the @code{print} command are saved in the @value{GDBN} |
| 7185 | @dfn{value history}. This allows you to refer to them in other expressions. |
| 7186 | Values are kept until the symbol table is re-read or discarded |
| 7187 | (for example with the @code{file} or @code{symbol-file} commands). |
| 7188 | When the symbol table changes, the value history is discarded, |
| 7189 | since the values may contain pointers back to the types defined in the |
| 7190 | symbol table. |
| 7191 | |
| 7192 | @cindex @code{$} |
| 7193 | @cindex @code{$$} |
| 7194 | @cindex history number |
| 7195 | The values printed are given @dfn{history numbers} by which you can |
| 7196 | refer to them. These are successive integers starting with one. |
| 7197 | @code{print} shows you the history number assigned to a value by |
| 7198 | printing @samp{$@var{num} = } before the value; here @var{num} is the |
| 7199 | history number. |
| 7200 | |
| 7201 | To refer to any previous value, use @samp{$} followed by the value's |
| 7202 | history number. The way @code{print} labels its output is designed to |
| 7203 | remind you of this. Just @code{$} refers to the most recent value in |
| 7204 | the history, and @code{$$} refers to the value before that. |
| 7205 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} |
| 7206 | is the value just prior to @code{$$}, @code{$$1} is equivalent to |
| 7207 | @code{$$}, and @code{$$0} is equivalent to @code{$}. |
| 7208 | |
| 7209 | For example, suppose you have just printed a pointer to a structure and |
| 7210 | want to see the contents of the structure. It suffices to type |
| 7211 | |
| 7212 | @smallexample |
| 7213 | p *$ |
| 7214 | @end smallexample |
| 7215 | |
| 7216 | If you have a chain of structures where the component @code{next} points |
| 7217 | to the next one, you can print the contents of the next one with this: |
| 7218 | |
| 7219 | @smallexample |
| 7220 | p *$.next |
| 7221 | @end smallexample |
| 7222 | |
| 7223 | @noindent |
| 7224 | You can print successive links in the chain by repeating this |
| 7225 | command---which you can do by just typing @key{RET}. |
| 7226 | |
| 7227 | Note that the history records values, not expressions. If the value of |
| 7228 | @code{x} is 4 and you type these commands: |
| 7229 | |
| 7230 | @smallexample |
| 7231 | print x |
| 7232 | set x=5 |
| 7233 | @end smallexample |
| 7234 | |
| 7235 | @noindent |
| 7236 | then the value recorded in the value history by the @code{print} command |
| 7237 | remains 4 even though the value of @code{x} has changed. |
| 7238 | |
| 7239 | @table @code |
| 7240 | @kindex show values |
| 7241 | @item show values |
| 7242 | Print the last ten values in the value history, with their item numbers. |
| 7243 | This is like @samp{p@ $$9} repeated ten times, except that @code{show |
| 7244 | values} does not change the history. |
| 7245 | |
| 7246 | @item show values @var{n} |
| 7247 | Print ten history values centered on history item number @var{n}. |
| 7248 | |
| 7249 | @item show values + |
| 7250 | Print ten history values just after the values last printed. If no more |
| 7251 | values are available, @code{show values +} produces no display. |
| 7252 | @end table |
| 7253 | |
| 7254 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the |
| 7255 | same effect as @samp{show values +}. |
| 7256 | |
| 7257 | @node Convenience Vars |
| 7258 | @section Convenience Variables |
| 7259 | |
| 7260 | @cindex convenience variables |
| 7261 | @cindex user-defined variables |
| 7262 | @value{GDBN} provides @dfn{convenience variables} that you can use within |
| 7263 | @value{GDBN} to hold on to a value and refer to it later. These variables |
| 7264 | exist entirely within @value{GDBN}; they are not part of your program, and |
| 7265 | setting a convenience variable has no direct effect on further execution |
| 7266 | of your program. That is why you can use them freely. |
| 7267 | |
| 7268 | Convenience variables are prefixed with @samp{$}. Any name preceded by |
| 7269 | @samp{$} can be used for a convenience variable, unless it is one of |
| 7270 | the predefined machine-specific register names (@pxref{Registers, ,Registers}). |
| 7271 | (Value history references, in contrast, are @emph{numbers} preceded |
| 7272 | by @samp{$}. @xref{Value History, ,Value History}.) |
| 7273 | |
| 7274 | You can save a value in a convenience variable with an assignment |
| 7275 | expression, just as you would set a variable in your program. |
| 7276 | For example: |
| 7277 | |
| 7278 | @smallexample |
| 7279 | set $foo = *object_ptr |
| 7280 | @end smallexample |
| 7281 | |
| 7282 | @noindent |
| 7283 | would save in @code{$foo} the value contained in the object pointed to by |
| 7284 | @code{object_ptr}. |
| 7285 | |
| 7286 | Using a convenience variable for the first time creates it, but its |
| 7287 | value is @code{void} until you assign a new value. You can alter the |
| 7288 | value with another assignment at any time. |
| 7289 | |
| 7290 | Convenience variables have no fixed types. You can assign a convenience |
| 7291 | variable any type of value, including structures and arrays, even if |
| 7292 | that variable already has a value of a different type. The convenience |
| 7293 | variable, when used as an expression, has the type of its current value. |
| 7294 | |
| 7295 | @table @code |
| 7296 | @kindex show convenience |
| 7297 | @cindex show all user variables |
| 7298 | @item show convenience |
| 7299 | Print a list of convenience variables used so far, and their values. |
| 7300 | Abbreviated @code{show conv}. |
| 7301 | |
| 7302 | @kindex init-if-undefined |
| 7303 | @cindex convenience variables, initializing |
| 7304 | @item init-if-undefined $@var{variable} = @var{expression} |
| 7305 | Set a convenience variable if it has not already been set. This is useful |
| 7306 | for user-defined commands that keep some state. It is similar, in concept, |
| 7307 | to using local static variables with initializers in C (except that |
| 7308 | convenience variables are global). It can also be used to allow users to |
| 7309 | override default values used in a command script. |
| 7310 | |
| 7311 | If the variable is already defined then the expression is not evaluated so |
| 7312 | any side-effects do not occur. |
| 7313 | @end table |
| 7314 | |
| 7315 | One of the ways to use a convenience variable is as a counter to be |
| 7316 | incremented or a pointer to be advanced. For example, to print |
| 7317 | a field from successive elements of an array of structures: |
| 7318 | |
| 7319 | @smallexample |
| 7320 | set $i = 0 |
| 7321 | print bar[$i++]->contents |
| 7322 | @end smallexample |
| 7323 | |
| 7324 | @noindent |
| 7325 | Repeat that command by typing @key{RET}. |
| 7326 | |
| 7327 | Some convenience variables are created automatically by @value{GDBN} and given |
| 7328 | values likely to be useful. |
| 7329 | |
| 7330 | @table @code |
| 7331 | @vindex $_@r{, convenience variable} |
| 7332 | @item $_ |
| 7333 | The variable @code{$_} is automatically set by the @code{x} command to |
| 7334 | the last address examined (@pxref{Memory, ,Examining Memory}). Other |
| 7335 | commands which provide a default address for @code{x} to examine also |
| 7336 | set @code{$_} to that address; these commands include @code{info line} |
| 7337 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} |
| 7338 | except when set by the @code{x} command, in which case it is a pointer |
| 7339 | to the type of @code{$__}. |
| 7340 | |
| 7341 | @vindex $__@r{, convenience variable} |
| 7342 | @item $__ |
| 7343 | The variable @code{$__} is automatically set by the @code{x} command |
| 7344 | to the value found in the last address examined. Its type is chosen |
| 7345 | to match the format in which the data was printed. |
| 7346 | |
| 7347 | @item $_exitcode |
| 7348 | @vindex $_exitcode@r{, convenience variable} |
| 7349 | The variable @code{$_exitcode} is automatically set to the exit code when |
| 7350 | the program being debugged terminates. |
| 7351 | @end table |
| 7352 | |
| 7353 | On HP-UX systems, if you refer to a function or variable name that |
| 7354 | begins with a dollar sign, @value{GDBN} searches for a user or system |
| 7355 | name first, before it searches for a convenience variable. |
| 7356 | |
| 7357 | @node Registers |
| 7358 | @section Registers |
| 7359 | |
| 7360 | @cindex registers |
| 7361 | You can refer to machine register contents, in expressions, as variables |
| 7362 | with names starting with @samp{$}. The names of registers are different |
| 7363 | for each machine; use @code{info registers} to see the names used on |
| 7364 | your machine. |
| 7365 | |
| 7366 | @table @code |
| 7367 | @kindex info registers |
| 7368 | @item info registers |
| 7369 | Print the names and values of all registers except floating-point |
| 7370 | and vector registers (in the selected stack frame). |
| 7371 | |
| 7372 | @kindex info all-registers |
| 7373 | @cindex floating point registers |
| 7374 | @item info all-registers |
| 7375 | Print the names and values of all registers, including floating-point |
| 7376 | and vector registers (in the selected stack frame). |
| 7377 | |
| 7378 | @item info registers @var{regname} @dots{} |
| 7379 | Print the @dfn{relativized} value of each specified register @var{regname}. |
| 7380 | As discussed in detail below, register values are normally relative to |
| 7381 | the selected stack frame. @var{regname} may be any register name valid on |
| 7382 | the machine you are using, with or without the initial @samp{$}. |
| 7383 | @end table |
| 7384 | |
| 7385 | @cindex stack pointer register |
| 7386 | @cindex program counter register |
| 7387 | @cindex process status register |
| 7388 | @cindex frame pointer register |
| 7389 | @cindex standard registers |
| 7390 | @value{GDBN} has four ``standard'' register names that are available (in |
| 7391 | expressions) on most machines---whenever they do not conflict with an |
| 7392 | architecture's canonical mnemonics for registers. The register names |
| 7393 | @code{$pc} and @code{$sp} are used for the program counter register and |
| 7394 | the stack pointer. @code{$fp} is used for a register that contains a |
| 7395 | pointer to the current stack frame, and @code{$ps} is used for a |
| 7396 | register that contains the processor status. For example, |
| 7397 | you could print the program counter in hex with |
| 7398 | |
| 7399 | @smallexample |
| 7400 | p/x $pc |
| 7401 | @end smallexample |
| 7402 | |
| 7403 | @noindent |
| 7404 | or print the instruction to be executed next with |
| 7405 | |
| 7406 | @smallexample |
| 7407 | x/i $pc |
| 7408 | @end smallexample |
| 7409 | |
| 7410 | @noindent |
| 7411 | or add four to the stack pointer@footnote{This is a way of removing |
| 7412 | one word from the stack, on machines where stacks grow downward in |
| 7413 | memory (most machines, nowadays). This assumes that the innermost |
| 7414 | stack frame is selected; setting @code{$sp} is not allowed when other |
| 7415 | stack frames are selected. To pop entire frames off the stack, |
| 7416 | regardless of machine architecture, use @code{return}; |
| 7417 | see @ref{Returning, ,Returning from a Function}.} with |
| 7418 | |
| 7419 | @smallexample |
| 7420 | set $sp += 4 |
| 7421 | @end smallexample |
| 7422 | |
| 7423 | Whenever possible, these four standard register names are available on |
| 7424 | your machine even though the machine has different canonical mnemonics, |
| 7425 | so long as there is no conflict. The @code{info registers} command |
| 7426 | shows the canonical names. For example, on the SPARC, @code{info |
| 7427 | registers} displays the processor status register as @code{$psr} but you |
| 7428 | can also refer to it as @code{$ps}; and on x86-based machines @code{$ps} |
| 7429 | is an alias for the @sc{eflags} register. |
| 7430 | |
| 7431 | @value{GDBN} always considers the contents of an ordinary register as an |
| 7432 | integer when the register is examined in this way. Some machines have |
| 7433 | special registers which can hold nothing but floating point; these |
| 7434 | registers are considered to have floating point values. There is no way |
| 7435 | to refer to the contents of an ordinary register as floating point value |
| 7436 | (although you can @emph{print} it as a floating point value with |
| 7437 | @samp{print/f $@var{regname}}). |
| 7438 | |
| 7439 | Some registers have distinct ``raw'' and ``virtual'' data formats. This |
| 7440 | means that the data format in which the register contents are saved by |
| 7441 | the operating system is not the same one that your program normally |
| 7442 | sees. For example, the registers of the 68881 floating point |
| 7443 | coprocessor are always saved in ``extended'' (raw) format, but all C |
| 7444 | programs expect to work with ``double'' (virtual) format. In such |
| 7445 | cases, @value{GDBN} normally works with the virtual format only (the format |
| 7446 | that makes sense for your program), but the @code{info registers} command |
| 7447 | prints the data in both formats. |
| 7448 | |
| 7449 | @cindex SSE registers (x86) |
| 7450 | @cindex MMX registers (x86) |
| 7451 | Some machines have special registers whose contents can be interpreted |
| 7452 | in several different ways. For example, modern x86-based machines |
| 7453 | have SSE and MMX registers that can hold several values packed |
| 7454 | together in several different formats. @value{GDBN} refers to such |
| 7455 | registers in @code{struct} notation: |
| 7456 | |
| 7457 | @smallexample |
| 7458 | (@value{GDBP}) print $xmm1 |
| 7459 | $1 = @{ |
| 7460 | v4_float = @{0, 3.43859137e-038, 1.54142831e-044, 1.821688e-044@}, |
| 7461 | v2_double = @{9.92129282474342e-303, 2.7585945287983262e-313@}, |
| 7462 | v16_int8 = "\000\000\000\000\3706;\001\v\000\000\000\r\000\000", |
| 7463 | v8_int16 = @{0, 0, 14072, 315, 11, 0, 13, 0@}, |
| 7464 | v4_int32 = @{0, 20657912, 11, 13@}, |
| 7465 | v2_int64 = @{88725056443645952, 55834574859@}, |
| 7466 | uint128 = 0x0000000d0000000b013b36f800000000 |
| 7467 | @} |
| 7468 | @end smallexample |
| 7469 | |
| 7470 | @noindent |
| 7471 | To set values of such registers, you need to tell @value{GDBN} which |
| 7472 | view of the register you wish to change, as if you were assigning |
| 7473 | value to a @code{struct} member: |
| 7474 | |
| 7475 | @smallexample |
| 7476 | (@value{GDBP}) set $xmm1.uint128 = 0x000000000000000000000000FFFFFFFF |
| 7477 | @end smallexample |
| 7478 | |
| 7479 | Normally, register values are relative to the selected stack frame |
| 7480 | (@pxref{Selection, ,Selecting a Frame}). This means that you get the |
| 7481 | value that the register would contain if all stack frames farther in |
| 7482 | were exited and their saved registers restored. In order to see the |
| 7483 | true contents of hardware registers, you must select the innermost |
| 7484 | frame (with @samp{frame 0}). |
| 7485 | |
| 7486 | However, @value{GDBN} must deduce where registers are saved, from the machine |
| 7487 | code generated by your compiler. If some registers are not saved, or if |
| 7488 | @value{GDBN} is unable to locate the saved registers, the selected stack |
| 7489 | frame makes no difference. |
| 7490 | |
| 7491 | @node Floating Point Hardware |
| 7492 | @section Floating Point Hardware |
| 7493 | @cindex floating point |
| 7494 | |
| 7495 | Depending on the configuration, @value{GDBN} may be able to give |
| 7496 | you more information about the status of the floating point hardware. |
| 7497 | |
| 7498 | @table @code |
| 7499 | @kindex info float |
| 7500 | @item info float |
| 7501 | Display hardware-dependent information about the floating |
| 7502 | point unit. The exact contents and layout vary depending on the |
| 7503 | floating point chip. Currently, @samp{info float} is supported on |
| 7504 | the ARM and x86 machines. |
| 7505 | @end table |
| 7506 | |
| 7507 | @node Vector Unit |
| 7508 | @section Vector Unit |
| 7509 | @cindex vector unit |
| 7510 | |
| 7511 | Depending on the configuration, @value{GDBN} may be able to give you |
| 7512 | more information about the status of the vector unit. |
| 7513 | |
| 7514 | @table @code |
| 7515 | @kindex info vector |
| 7516 | @item info vector |
| 7517 | Display information about the vector unit. The exact contents and |
| 7518 | layout vary depending on the hardware. |
| 7519 | @end table |
| 7520 | |
| 7521 | @node OS Information |
| 7522 | @section Operating System Auxiliary Information |
| 7523 | @cindex OS information |
| 7524 | |
| 7525 | @value{GDBN} provides interfaces to useful OS facilities that can help |
| 7526 | you debug your program. |
| 7527 | |
| 7528 | @cindex @code{ptrace} system call |
| 7529 | @cindex @code{struct user} contents |
| 7530 | When @value{GDBN} runs on a @dfn{Posix system} (such as GNU or Unix |
| 7531 | machines), it interfaces with the inferior via the @code{ptrace} |
| 7532 | system call. The operating system creates a special sata structure, |
| 7533 | called @code{struct user}, for this interface. You can use the |
| 7534 | command @code{info udot} to display the contents of this data |
| 7535 | structure. |
| 7536 | |
| 7537 | @table @code |
| 7538 | @item info udot |
| 7539 | @kindex info udot |
| 7540 | Display the contents of the @code{struct user} maintained by the OS |
| 7541 | kernel for the program being debugged. @value{GDBN} displays the |
| 7542 | contents of @code{struct user} as a list of hex numbers, similar to |
| 7543 | the @code{examine} command. |
| 7544 | @end table |
| 7545 | |
| 7546 | @cindex auxiliary vector |
| 7547 | @cindex vector, auxiliary |
| 7548 | Some operating systems supply an @dfn{auxiliary vector} to programs at |
| 7549 | startup. This is akin to the arguments and environment that you |
| 7550 | specify for a program, but contains a system-dependent variety of |
| 7551 | binary values that tell system libraries important details about the |
| 7552 | hardware, operating system, and process. Each value's purpose is |
| 7553 | identified by an integer tag; the meanings are well-known but system-specific. |
| 7554 | Depending on the configuration and operating system facilities, |
| 7555 | @value{GDBN} may be able to show you this information. For remote |
| 7556 | targets, this functionality may further depend on the remote stub's |
| 7557 | support of the @samp{qXfer:auxv:read} packet, see |
| 7558 | @ref{qXfer auxiliary vector read}. |
| 7559 | |
| 7560 | @table @code |
| 7561 | @kindex info auxv |
| 7562 | @item info auxv |
| 7563 | Display the auxiliary vector of the inferior, which can be either a |
| 7564 | live process or a core dump file. @value{GDBN} prints each tag value |
| 7565 | numerically, and also shows names and text descriptions for recognized |
| 7566 | tags. Some values in the vector are numbers, some bit masks, and some |
| 7567 | pointers to strings or other data. @value{GDBN} displays each value in the |
| 7568 | most appropriate form for a recognized tag, and in hexadecimal for |
| 7569 | an unrecognized tag. |
| 7570 | @end table |
| 7571 | |
| 7572 | On some targets, @value{GDBN} can access operating-system-specific information |
| 7573 | and display it to user, without interpretation. For remote targets, |
| 7574 | this functionality depends on the remote stub's support of the |
| 7575 | @samp{qXfer:osdata:read} packet, see @ref{qXfer osdata read}. |
| 7576 | |
| 7577 | @table @code |
| 7578 | @kindex info os processes |
| 7579 | @item info os processes |
| 7580 | Display the list of processes on the target. For each process, |
| 7581 | @value{GDBN} prints the process identifier, the name of the user, and |
| 7582 | the command corresponding to the process. |
| 7583 | @end table |
| 7584 | |
| 7585 | @node Memory Region Attributes |
| 7586 | @section Memory Region Attributes |
| 7587 | @cindex memory region attributes |
| 7588 | |
| 7589 | @dfn{Memory region attributes} allow you to describe special handling |
| 7590 | required by regions of your target's memory. @value{GDBN} uses |
| 7591 | attributes to determine whether to allow certain types of memory |
| 7592 | accesses; whether to use specific width accesses; and whether to cache |
| 7593 | target memory. By default the description of memory regions is |
| 7594 | fetched from the target (if the current target supports this), but the |
| 7595 | user can override the fetched regions. |
| 7596 | |
| 7597 | Defined memory regions can be individually enabled and disabled. When a |
| 7598 | memory region is disabled, @value{GDBN} uses the default attributes when |
| 7599 | accessing memory in that region. Similarly, if no memory regions have |
| 7600 | been defined, @value{GDBN} uses the default attributes when accessing |
| 7601 | all memory. |
| 7602 | |
| 7603 | When a memory region is defined, it is given a number to identify it; |
| 7604 | to enable, disable, or remove a memory region, you specify that number. |
| 7605 | |
| 7606 | @table @code |
| 7607 | @kindex mem |
| 7608 | @item mem @var{lower} @var{upper} @var{attributes}@dots{} |
| 7609 | Define a memory region bounded by @var{lower} and @var{upper} with |
| 7610 | attributes @var{attributes}@dots{}, and add it to the list of regions |
| 7611 | monitored by @value{GDBN}. Note that @var{upper} == 0 is a special |
| 7612 | case: it is treated as the target's maximum memory address. |
| 7613 | (0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.) |
| 7614 | |
| 7615 | @item mem auto |
| 7616 | Discard any user changes to the memory regions and use target-supplied |
| 7617 | regions, if available, or no regions if the target does not support. |
| 7618 | |
| 7619 | @kindex delete mem |
| 7620 | @item delete mem @var{nums}@dots{} |
| 7621 | Remove memory regions @var{nums}@dots{} from the list of regions |
| 7622 | monitored by @value{GDBN}. |
| 7623 | |
| 7624 | @kindex disable mem |
| 7625 | @item disable mem @var{nums}@dots{} |
| 7626 | Disable monitoring of memory regions @var{nums}@dots{}. |
| 7627 | A disabled memory region is not forgotten. |
| 7628 | It may be enabled again later. |
| 7629 | |
| 7630 | @kindex enable mem |
| 7631 | @item enable mem @var{nums}@dots{} |
| 7632 | Enable monitoring of memory regions @var{nums}@dots{}. |
| 7633 | |
| 7634 | @kindex info mem |
| 7635 | @item info mem |
| 7636 | Print a table of all defined memory regions, with the following columns |
| 7637 | for each region: |
| 7638 | |
| 7639 | @table @emph |
| 7640 | @item Memory Region Number |
| 7641 | @item Enabled or Disabled. |
| 7642 | Enabled memory regions are marked with @samp{y}. |
| 7643 | Disabled memory regions are marked with @samp{n}. |
| 7644 | |
| 7645 | @item Lo Address |
| 7646 | The address defining the inclusive lower bound of the memory region. |
| 7647 | |
| 7648 | @item Hi Address |
| 7649 | The address defining the exclusive upper bound of the memory region. |
| 7650 | |
| 7651 | @item Attributes |
| 7652 | The list of attributes set for this memory region. |
| 7653 | @end table |
| 7654 | @end table |
| 7655 | |
| 7656 | |
| 7657 | @subsection Attributes |
| 7658 | |
| 7659 | @subsubsection Memory Access Mode |
| 7660 | The access mode attributes set whether @value{GDBN} may make read or |
| 7661 | write accesses to a memory region. |
| 7662 | |
| 7663 | While these attributes prevent @value{GDBN} from performing invalid |
| 7664 | memory accesses, they do nothing to prevent the target system, I/O DMA, |
| 7665 | etc.@: from accessing memory. |
| 7666 | |
| 7667 | @table @code |
| 7668 | @item ro |
| 7669 | Memory is read only. |
| 7670 | @item wo |
| 7671 | Memory is write only. |
| 7672 | @item rw |
| 7673 | Memory is read/write. This is the default. |
| 7674 | @end table |
| 7675 | |
| 7676 | @subsubsection Memory Access Size |
| 7677 | The access size attribute tells @value{GDBN} to use specific sized |
| 7678 | accesses in the memory region. Often memory mapped device registers |
| 7679 | require specific sized accesses. If no access size attribute is |
| 7680 | specified, @value{GDBN} may use accesses of any size. |
| 7681 | |
| 7682 | @table @code |
| 7683 | @item 8 |
| 7684 | Use 8 bit memory accesses. |
| 7685 | @item 16 |
| 7686 | Use 16 bit memory accesses. |
| 7687 | @item 32 |
| 7688 | Use 32 bit memory accesses. |
| 7689 | @item 64 |
| 7690 | Use 64 bit memory accesses. |
| 7691 | @end table |
| 7692 | |
| 7693 | @c @subsubsection Hardware/Software Breakpoints |
| 7694 | @c The hardware/software breakpoint attributes set whether @value{GDBN} |
| 7695 | @c will use hardware or software breakpoints for the internal breakpoints |
| 7696 | @c used by the step, next, finish, until, etc. commands. |
| 7697 | @c |
| 7698 | @c @table @code |
| 7699 | @c @item hwbreak |
| 7700 | @c Always use hardware breakpoints |
| 7701 | @c @item swbreak (default) |
| 7702 | @c @end table |
| 7703 | |
| 7704 | @subsubsection Data Cache |
| 7705 | The data cache attributes set whether @value{GDBN} will cache target |
| 7706 | memory. While this generally improves performance by reducing debug |
| 7707 | protocol overhead, it can lead to incorrect results because @value{GDBN} |
| 7708 | does not know about volatile variables or memory mapped device |
| 7709 | registers. |
| 7710 | |
| 7711 | @table @code |
| 7712 | @item cache |
| 7713 | Enable @value{GDBN} to cache target memory. |
| 7714 | @item nocache |
| 7715 | Disable @value{GDBN} from caching target memory. This is the default. |
| 7716 | @end table |
| 7717 | |
| 7718 | @subsection Memory Access Checking |
| 7719 | @value{GDBN} can be instructed to refuse accesses to memory that is |
| 7720 | not explicitly described. This can be useful if accessing such |
| 7721 | regions has undesired effects for a specific target, or to provide |
| 7722 | better error checking. The following commands control this behaviour. |
| 7723 | |
| 7724 | @table @code |
| 7725 | @kindex set mem inaccessible-by-default |
| 7726 | @item set mem inaccessible-by-default [on|off] |
| 7727 | If @code{on} is specified, make @value{GDBN} treat memory not |
| 7728 | explicitly described by the memory ranges as non-existent and refuse accesses |
| 7729 | to such memory. The checks are only performed if there's at least one |
| 7730 | memory range defined. If @code{off} is specified, make @value{GDBN} |
| 7731 | treat the memory not explicitly described by the memory ranges as RAM. |
| 7732 | The default value is @code{on}. |
| 7733 | @kindex show mem inaccessible-by-default |
| 7734 | @item show mem inaccessible-by-default |
| 7735 | Show the current handling of accesses to unknown memory. |
| 7736 | @end table |
| 7737 | |
| 7738 | |
| 7739 | @c @subsubsection Memory Write Verification |
| 7740 | @c The memory write verification attributes set whether @value{GDBN} |
| 7741 | @c will re-reads data after each write to verify the write was successful. |
| 7742 | @c |
| 7743 | @c @table @code |
| 7744 | @c @item verify |
| 7745 | @c @item noverify (default) |
| 7746 | @c @end table |
| 7747 | |
| 7748 | @node Dump/Restore Files |
| 7749 | @section Copy Between Memory and a File |
| 7750 | @cindex dump/restore files |
| 7751 | @cindex append data to a file |
| 7752 | @cindex dump data to a file |
| 7753 | @cindex restore data from a file |
| 7754 | |
| 7755 | You can use the commands @code{dump}, @code{append}, and |
| 7756 | @code{restore} to copy data between target memory and a file. The |
| 7757 | @code{dump} and @code{append} commands write data to a file, and the |
| 7758 | @code{restore} command reads data from a file back into the inferior's |
| 7759 | memory. Files may be in binary, Motorola S-record, Intel hex, or |
| 7760 | Tektronix Hex format; however, @value{GDBN} can only append to binary |
| 7761 | files. |
| 7762 | |
| 7763 | @table @code |
| 7764 | |
| 7765 | @kindex dump |
| 7766 | @item dump @r{[}@var{format}@r{]} memory @var{filename} @var{start_addr} @var{end_addr} |
| 7767 | @itemx dump @r{[}@var{format}@r{]} value @var{filename} @var{expr} |
| 7768 | Dump the contents of memory from @var{start_addr} to @var{end_addr}, |
| 7769 | or the value of @var{expr}, to @var{filename} in the given format. |
| 7770 | |
| 7771 | The @var{format} parameter may be any one of: |
| 7772 | @table @code |
| 7773 | @item binary |
| 7774 | Raw binary form. |
| 7775 | @item ihex |
| 7776 | Intel hex format. |
| 7777 | @item srec |
| 7778 | Motorola S-record format. |
| 7779 | @item tekhex |
| 7780 | Tektronix Hex format. |
| 7781 | @end table |
| 7782 | |
| 7783 | @value{GDBN} uses the same definitions of these formats as the |
| 7784 | @sc{gnu} binary utilities, like @samp{objdump} and @samp{objcopy}. If |
| 7785 | @var{format} is omitted, @value{GDBN} dumps the data in raw binary |
| 7786 | form. |
| 7787 | |
| 7788 | @kindex append |
| 7789 | @item append @r{[}binary@r{]} memory @var{filename} @var{start_addr} @var{end_addr} |
| 7790 | @itemx append @r{[}binary@r{]} value @var{filename} @var{expr} |
| 7791 | Append the contents of memory from @var{start_addr} to @var{end_addr}, |
| 7792 | or the value of @var{expr}, to the file @var{filename}, in raw binary form. |
| 7793 | (@value{GDBN} can only append data to files in raw binary form.) |
| 7794 | |
| 7795 | @kindex restore |
| 7796 | @item restore @var{filename} @r{[}binary@r{]} @var{bias} @var{start} @var{end} |
| 7797 | Restore the contents of file @var{filename} into memory. The |
| 7798 | @code{restore} command can automatically recognize any known @sc{bfd} |
| 7799 | file format, except for raw binary. To restore a raw binary file you |
| 7800 | must specify the optional keyword @code{binary} after the filename. |
| 7801 | |
| 7802 | If @var{bias} is non-zero, its value will be added to the addresses |
| 7803 | contained in the file. Binary files always start at address zero, so |
| 7804 | they will be restored at address @var{bias}. Other bfd files have |
| 7805 | a built-in location; they will be restored at offset @var{bias} |
| 7806 | from that location. |
| 7807 | |
| 7808 | If @var{start} and/or @var{end} are non-zero, then only data between |
| 7809 | file offset @var{start} and file offset @var{end} will be restored. |
| 7810 | These offsets are relative to the addresses in the file, before |
| 7811 | the @var{bias} argument is applied. |
| 7812 | |
| 7813 | @end table |
| 7814 | |
| 7815 | @node Core File Generation |
| 7816 | @section How to Produce a Core File from Your Program |
| 7817 | @cindex dump core from inferior |
| 7818 | |
| 7819 | A @dfn{core file} or @dfn{core dump} is a file that records the memory |
| 7820 | image of a running process and its process status (register values |
| 7821 | etc.). Its primary use is post-mortem debugging of a program that |
| 7822 | crashed while it ran outside a debugger. A program that crashes |
| 7823 | automatically produces a core file, unless this feature is disabled by |
| 7824 | the user. @xref{Files}, for information on invoking @value{GDBN} in |
| 7825 | the post-mortem debugging mode. |
| 7826 | |
| 7827 | Occasionally, you may wish to produce a core file of the program you |
| 7828 | are debugging in order to preserve a snapshot of its state. |
| 7829 | @value{GDBN} has a special command for that. |
| 7830 | |
| 7831 | @table @code |
| 7832 | @kindex gcore |
| 7833 | @kindex generate-core-file |
| 7834 | @item generate-core-file [@var{file}] |
| 7835 | @itemx gcore [@var{file}] |
| 7836 | Produce a core dump of the inferior process. The optional argument |
| 7837 | @var{file} specifies the file name where to put the core dump. If not |
| 7838 | specified, the file name defaults to @file{core.@var{pid}}, where |
| 7839 | @var{pid} is the inferior process ID. |
| 7840 | |
| 7841 | Note that this command is implemented only for some systems (as of |
| 7842 | this writing, @sc{gnu}/Linux, FreeBSD, Solaris, Unixware, and S390). |
| 7843 | @end table |
| 7844 | |
| 7845 | @node Character Sets |
| 7846 | @section Character Sets |
| 7847 | @cindex character sets |
| 7848 | @cindex charset |
| 7849 | @cindex translating between character sets |
| 7850 | @cindex host character set |
| 7851 | @cindex target character set |
| 7852 | |
| 7853 | If the program you are debugging uses a different character set to |
| 7854 | represent characters and strings than the one @value{GDBN} uses itself, |
| 7855 | @value{GDBN} can automatically translate between the character sets for |
| 7856 | you. The character set @value{GDBN} uses we call the @dfn{host |
| 7857 | character set}; the one the inferior program uses we call the |
| 7858 | @dfn{target character set}. |
| 7859 | |
| 7860 | For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which |
| 7861 | uses the ISO Latin 1 character set, but you are using @value{GDBN}'s |
| 7862 | remote protocol (@pxref{Remote Debugging}) to debug a program |
| 7863 | running on an IBM mainframe, which uses the @sc{ebcdic} character set, |
| 7864 | then the host character set is Latin-1, and the target character set is |
| 7865 | @sc{ebcdic}. If you give @value{GDBN} the command @code{set |
| 7866 | target-charset EBCDIC-US}, then @value{GDBN} translates between |
| 7867 | @sc{ebcdic} and Latin 1 as you print character or string values, or use |
| 7868 | character and string literals in expressions. |
| 7869 | |
| 7870 | @value{GDBN} has no way to automatically recognize which character set |
| 7871 | the inferior program uses; you must tell it, using the @code{set |
| 7872 | target-charset} command, described below. |
| 7873 | |
| 7874 | Here are the commands for controlling @value{GDBN}'s character set |
| 7875 | support: |
| 7876 | |
| 7877 | @table @code |
| 7878 | @item set target-charset @var{charset} |
| 7879 | @kindex set target-charset |
| 7880 | Set the current target character set to @var{charset}. We list the |
| 7881 | character set names @value{GDBN} recognizes below, but if you type |
| 7882 | @code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will |
| 7883 | list the target character sets it supports. |
| 7884 | @end table |
| 7885 | |
| 7886 | @table @code |
| 7887 | @item set host-charset @var{charset} |
| 7888 | @kindex set host-charset |
| 7889 | Set the current host character set to @var{charset}. |
| 7890 | |
| 7891 | By default, @value{GDBN} uses a host character set appropriate to the |
| 7892 | system it is running on; you can override that default using the |
| 7893 | @code{set host-charset} command. |
| 7894 | |
| 7895 | @value{GDBN} can only use certain character sets as its host character |
| 7896 | set. We list the character set names @value{GDBN} recognizes below, and |
| 7897 | indicate which can be host character sets, but if you type |
| 7898 | @code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will |
| 7899 | list the host character sets it supports. |
| 7900 | |
| 7901 | @item set charset @var{charset} |
| 7902 | @kindex set charset |
| 7903 | Set the current host and target character sets to @var{charset}. As |
| 7904 | above, if you type @code{set charset} followed by @key{TAB}@key{TAB}, |
| 7905 | @value{GDBN} will list the name of the character sets that can be used |
| 7906 | for both host and target. |
| 7907 | |
| 7908 | |
| 7909 | @item show charset |
| 7910 | @kindex show charset |
| 7911 | Show the names of the current host and target charsets. |
| 7912 | |
| 7913 | @itemx show host-charset |
| 7914 | @kindex show host-charset |
| 7915 | Show the name of the current host charset. |
| 7916 | |
| 7917 | @itemx show target-charset |
| 7918 | @kindex show target-charset |
| 7919 | Show the name of the current target charset. |
| 7920 | |
| 7921 | @end table |
| 7922 | |
| 7923 | @value{GDBN} currently includes support for the following character |
| 7924 | sets: |
| 7925 | |
| 7926 | @table @code |
| 7927 | |
| 7928 | @item ASCII |
| 7929 | @cindex ASCII character set |
| 7930 | Seven-bit U.S. @sc{ascii}. @value{GDBN} can use this as its host |
| 7931 | character set. |
| 7932 | |
| 7933 | @item ISO-8859-1 |
| 7934 | @cindex ISO 8859-1 character set |
| 7935 | @cindex ISO Latin 1 character set |
| 7936 | The ISO Latin 1 character set. This extends @sc{ascii} with accented |
| 7937 | characters needed for French, German, and Spanish. @value{GDBN} can use |
| 7938 | this as its host character set. |
| 7939 | |
| 7940 | @item EBCDIC-US |
| 7941 | @itemx IBM1047 |
| 7942 | @cindex EBCDIC character set |
| 7943 | @cindex IBM1047 character set |
| 7944 | Variants of the @sc{ebcdic} character set, used on some of IBM's |
| 7945 | mainframe operating systems. (@sc{gnu}/Linux on the S/390 uses U.S. @sc{ascii}.) |
| 7946 | @value{GDBN} cannot use these as its host character set. |
| 7947 | |
| 7948 | @end table |
| 7949 | |
| 7950 | Note that these are all single-byte character sets. More work inside |
| 7951 | @value{GDBN} is needed to support multi-byte or variable-width character |
| 7952 | encodings, like the UTF-8 and UCS-2 encodings of Unicode. |
| 7953 | |
| 7954 | Here is an example of @value{GDBN}'s character set support in action. |
| 7955 | Assume that the following source code has been placed in the file |
| 7956 | @file{charset-test.c}: |
| 7957 | |
| 7958 | @smallexample |
| 7959 | #include <stdio.h> |
| 7960 | |
| 7961 | char ascii_hello[] |
| 7962 | = @{72, 101, 108, 108, 111, 44, 32, 119, |
| 7963 | 111, 114, 108, 100, 33, 10, 0@}; |
| 7964 | char ibm1047_hello[] |
| 7965 | = @{200, 133, 147, 147, 150, 107, 64, 166, |
| 7966 | 150, 153, 147, 132, 90, 37, 0@}; |
| 7967 | |
| 7968 | main () |
| 7969 | @{ |
| 7970 | printf ("Hello, world!\n"); |
| 7971 | @} |
| 7972 | @end smallexample |
| 7973 | |
| 7974 | In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays |
| 7975 | containing the string @samp{Hello, world!} followed by a newline, |
| 7976 | encoded in the @sc{ascii} and @sc{ibm1047} character sets. |
| 7977 | |
| 7978 | We compile the program, and invoke the debugger on it: |
| 7979 | |
| 7980 | @smallexample |
| 7981 | $ gcc -g charset-test.c -o charset-test |
| 7982 | $ gdb -nw charset-test |
| 7983 | GNU gdb 2001-12-19-cvs |
| 7984 | Copyright 2001 Free Software Foundation, Inc. |
| 7985 | @dots{} |
| 7986 | (@value{GDBP}) |
| 7987 | @end smallexample |
| 7988 | |
| 7989 | We can use the @code{show charset} command to see what character sets |
| 7990 | @value{GDBN} is currently using to interpret and display characters and |
| 7991 | strings: |
| 7992 | |
| 7993 | @smallexample |
| 7994 | (@value{GDBP}) show charset |
| 7995 | The current host and target character set is `ISO-8859-1'. |
| 7996 | (@value{GDBP}) |
| 7997 | @end smallexample |
| 7998 | |
| 7999 | For the sake of printing this manual, let's use @sc{ascii} as our |
| 8000 | initial character set: |
| 8001 | @smallexample |
| 8002 | (@value{GDBP}) set charset ASCII |
| 8003 | (@value{GDBP}) show charset |
| 8004 | The current host and target character set is `ASCII'. |
| 8005 | (@value{GDBP}) |
| 8006 | @end smallexample |
| 8007 | |
| 8008 | Let's assume that @sc{ascii} is indeed the correct character set for our |
| 8009 | host system --- in other words, let's assume that if @value{GDBN} prints |
| 8010 | characters using the @sc{ascii} character set, our terminal will display |
| 8011 | them properly. Since our current target character set is also |
| 8012 | @sc{ascii}, the contents of @code{ascii_hello} print legibly: |
| 8013 | |
| 8014 | @smallexample |
| 8015 | (@value{GDBP}) print ascii_hello |
| 8016 | $1 = 0x401698 "Hello, world!\n" |
| 8017 | (@value{GDBP}) print ascii_hello[0] |
| 8018 | $2 = 72 'H' |
| 8019 | (@value{GDBP}) |
| 8020 | @end smallexample |
| 8021 | |
| 8022 | @value{GDBN} uses the target character set for character and string |
| 8023 | literals you use in expressions: |
| 8024 | |
| 8025 | @smallexample |
| 8026 | (@value{GDBP}) print '+' |
| 8027 | $3 = 43 '+' |
| 8028 | (@value{GDBP}) |
| 8029 | @end smallexample |
| 8030 | |
| 8031 | The @sc{ascii} character set uses the number 43 to encode the @samp{+} |
| 8032 | character. |
| 8033 | |
| 8034 | @value{GDBN} relies on the user to tell it which character set the |
| 8035 | target program uses. If we print @code{ibm1047_hello} while our target |
| 8036 | character set is still @sc{ascii}, we get jibberish: |
| 8037 | |
| 8038 | @smallexample |
| 8039 | (@value{GDBP}) print ibm1047_hello |
| 8040 | $4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%" |
| 8041 | (@value{GDBP}) print ibm1047_hello[0] |
| 8042 | $5 = 200 '\310' |
| 8043 | (@value{GDBP}) |
| 8044 | @end smallexample |
| 8045 | |
| 8046 | If we invoke the @code{set target-charset} followed by @key{TAB}@key{TAB}, |
| 8047 | @value{GDBN} tells us the character sets it supports: |
| 8048 | |
| 8049 | @smallexample |
| 8050 | (@value{GDBP}) set target-charset |
| 8051 | ASCII EBCDIC-US IBM1047 ISO-8859-1 |
| 8052 | (@value{GDBP}) set target-charset |
| 8053 | @end smallexample |
| 8054 | |
| 8055 | We can select @sc{ibm1047} as our target character set, and examine the |
| 8056 | program's strings again. Now the @sc{ascii} string is wrong, but |
| 8057 | @value{GDBN} translates the contents of @code{ibm1047_hello} from the |
| 8058 | target character set, @sc{ibm1047}, to the host character set, |
| 8059 | @sc{ascii}, and they display correctly: |
| 8060 | |
| 8061 | @smallexample |
| 8062 | (@value{GDBP}) set target-charset IBM1047 |
| 8063 | (@value{GDBP}) show charset |
| 8064 | The current host character set is `ASCII'. |
| 8065 | The current target character set is `IBM1047'. |
| 8066 | (@value{GDBP}) print ascii_hello |
| 8067 | $6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012" |
| 8068 | (@value{GDBP}) print ascii_hello[0] |
| 8069 | $7 = 72 '\110' |
| 8070 | (@value{GDBP}) print ibm1047_hello |
| 8071 | $8 = 0x4016a8 "Hello, world!\n" |
| 8072 | (@value{GDBP}) print ibm1047_hello[0] |
| 8073 | $9 = 200 'H' |
| 8074 | (@value{GDBP}) |
| 8075 | @end smallexample |
| 8076 | |
| 8077 | As above, @value{GDBN} uses the target character set for character and |
| 8078 | string literals you use in expressions: |
| 8079 | |
| 8080 | @smallexample |
| 8081 | (@value{GDBP}) print '+' |
| 8082 | $10 = 78 '+' |
| 8083 | (@value{GDBP}) |
| 8084 | @end smallexample |
| 8085 | |
| 8086 | The @sc{ibm1047} character set uses the number 78 to encode the @samp{+} |
| 8087 | character. |
| 8088 | |
| 8089 | @node Caching Remote Data |
| 8090 | @section Caching Data of Remote Targets |
| 8091 | @cindex caching data of remote targets |
| 8092 | |
| 8093 | @value{GDBN} can cache data exchanged between the debugger and a |
| 8094 | remote target (@pxref{Remote Debugging}). Such caching generally improves |
| 8095 | performance, because it reduces the overhead of the remote protocol by |
| 8096 | bundling memory reads and writes into large chunks. Unfortunately, |
| 8097 | @value{GDBN} does not currently know anything about volatile |
| 8098 | registers, and thus data caching will produce incorrect results when |
| 8099 | volatile registers are in use. |
| 8100 | |
| 8101 | @table @code |
| 8102 | @kindex set remotecache |
| 8103 | @item set remotecache on |
| 8104 | @itemx set remotecache off |
| 8105 | Set caching state for remote targets. When @code{ON}, use data |
| 8106 | caching. By default, this option is @code{OFF}. |
| 8107 | |
| 8108 | @kindex show remotecache |
| 8109 | @item show remotecache |
| 8110 | Show the current state of data caching for remote targets. |
| 8111 | |
| 8112 | @kindex info dcache |
| 8113 | @item info dcache |
| 8114 | Print the information about the data cache performance. The |
| 8115 | information displayed includes: the dcache width and depth; and for |
| 8116 | each cache line, how many times it was referenced, and its data and |
| 8117 | state (invalid, dirty, valid). This command is useful for debugging |
| 8118 | the data cache operation. |
| 8119 | @end table |
| 8120 | |
| 8121 | @node Searching Memory |
| 8122 | @section Search Memory |
| 8123 | @cindex searching memory |
| 8124 | |
| 8125 | Memory can be searched for a particular sequence of bytes with the |
| 8126 | @code{find} command. |
| 8127 | |
| 8128 | @table @code |
| 8129 | @kindex find |
| 8130 | @item find @r{[}/@var{sn}@r{]} @var{start_addr}, +@var{len}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]} |
| 8131 | @itemx find @r{[}/@var{sn}@r{]} @var{start_addr}, @var{end_addr}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]} |
| 8132 | Search memory for the sequence of bytes specified by @var{val1}, @var{val2}, |
| 8133 | etc. The search begins at address @var{start_addr} and continues for either |
| 8134 | @var{len} bytes or through to @var{end_addr} inclusive. |
| 8135 | @end table |
| 8136 | |
| 8137 | @var{s} and @var{n} are optional parameters. |
| 8138 | They may be specified in either order, apart or together. |
| 8139 | |
| 8140 | @table @r |
| 8141 | @item @var{s}, search query size |
| 8142 | The size of each search query value. |
| 8143 | |
| 8144 | @table @code |
| 8145 | @item b |
| 8146 | bytes |
| 8147 | @item h |
| 8148 | halfwords (two bytes) |
| 8149 | @item w |
| 8150 | words (four bytes) |
| 8151 | @item g |
| 8152 | giant words (eight bytes) |
| 8153 | @end table |
| 8154 | |
| 8155 | All values are interpreted in the current language. |
| 8156 | This means, for example, that if the current source language is C/C@t{++} |
| 8157 | then searching for the string ``hello'' includes the trailing '\0'. |
| 8158 | |
| 8159 | If the value size is not specified, it is taken from the |
| 8160 | value's type in the current language. |
| 8161 | This is useful when one wants to specify the search |
| 8162 | pattern as a mixture of types. |
| 8163 | Note that this means, for example, that in the case of C-like languages |
| 8164 | a search for an untyped 0x42 will search for @samp{(int) 0x42} |
| 8165 | which is typically four bytes. |
| 8166 | |
| 8167 | @item @var{n}, maximum number of finds |
| 8168 | The maximum number of matches to print. The default is to print all finds. |
| 8169 | @end table |
| 8170 | |
| 8171 | You can use strings as search values. Quote them with double-quotes |
| 8172 | (@code{"}). |
| 8173 | The string value is copied into the search pattern byte by byte, |
| 8174 | regardless of the endianness of the target and the size specification. |
| 8175 | |
| 8176 | The address of each match found is printed as well as a count of the |
| 8177 | number of matches found. |
| 8178 | |
| 8179 | The address of the last value found is stored in convenience variable |
| 8180 | @samp{$_}. |
| 8181 | A count of the number of matches is stored in @samp{$numfound}. |
| 8182 | |
| 8183 | For example, if stopped at the @code{printf} in this function: |
| 8184 | |
| 8185 | @smallexample |
| 8186 | void |
| 8187 | hello () |
| 8188 | @{ |
| 8189 | static char hello[] = "hello-hello"; |
| 8190 | static struct @{ char c; short s; int i; @} |
| 8191 | __attribute__ ((packed)) mixed |
| 8192 | = @{ 'c', 0x1234, 0x87654321 @}; |
| 8193 | printf ("%s\n", hello); |
| 8194 | @} |
| 8195 | @end smallexample |
| 8196 | |
| 8197 | @noindent |
| 8198 | you get during debugging: |
| 8199 | |
| 8200 | @smallexample |
| 8201 | (gdb) find &hello[0], +sizeof(hello), "hello" |
| 8202 | 0x804956d <hello.1620+6> |
| 8203 | 1 pattern found |
| 8204 | (gdb) find &hello[0], +sizeof(hello), 'h', 'e', 'l', 'l', 'o' |
| 8205 | 0x8049567 <hello.1620> |
| 8206 | 0x804956d <hello.1620+6> |
| 8207 | 2 patterns found |
| 8208 | (gdb) find /b1 &hello[0], +sizeof(hello), 'h', 0x65, 'l' |
| 8209 | 0x8049567 <hello.1620> |
| 8210 | 1 pattern found |
| 8211 | (gdb) find &mixed, +sizeof(mixed), (char) 'c', (short) 0x1234, (int) 0x87654321 |
| 8212 | 0x8049560 <mixed.1625> |
| 8213 | 1 pattern found |
| 8214 | (gdb) print $numfound |
| 8215 | $1 = 1 |
| 8216 | (gdb) print $_ |
| 8217 | $2 = (void *) 0x8049560 |
| 8218 | @end smallexample |
| 8219 | |
| 8220 | @node Macros |
| 8221 | @chapter C Preprocessor Macros |
| 8222 | |
| 8223 | Some languages, such as C and C@t{++}, provide a way to define and invoke |
| 8224 | ``preprocessor macros'' which expand into strings of tokens. |
| 8225 | @value{GDBN} can evaluate expressions containing macro invocations, show |
| 8226 | the result of macro expansion, and show a macro's definition, including |
| 8227 | where it was defined. |
| 8228 | |
| 8229 | You may need to compile your program specially to provide @value{GDBN} |
| 8230 | with information about preprocessor macros. Most compilers do not |
| 8231 | include macros in their debugging information, even when you compile |
| 8232 | with the @option{-g} flag. @xref{Compilation}. |
| 8233 | |
| 8234 | A program may define a macro at one point, remove that definition later, |
| 8235 | and then provide a different definition after that. Thus, at different |
| 8236 | points in the program, a macro may have different definitions, or have |
| 8237 | no definition at all. If there is a current stack frame, @value{GDBN} |
| 8238 | uses the macros in scope at that frame's source code line. Otherwise, |
| 8239 | @value{GDBN} uses the macros in scope at the current listing location; |
| 8240 | see @ref{List}. |
| 8241 | |
| 8242 | Whenever @value{GDBN} evaluates an expression, it always expands any |
| 8243 | macro invocations present in the expression. @value{GDBN} also provides |
| 8244 | the following commands for working with macros explicitly. |
| 8245 | |
| 8246 | @table @code |
| 8247 | |
| 8248 | @kindex macro expand |
| 8249 | @cindex macro expansion, showing the results of preprocessor |
| 8250 | @cindex preprocessor macro expansion, showing the results of |
| 8251 | @cindex expanding preprocessor macros |
| 8252 | @item macro expand @var{expression} |
| 8253 | @itemx macro exp @var{expression} |
| 8254 | Show the results of expanding all preprocessor macro invocations in |
| 8255 | @var{expression}. Since @value{GDBN} simply expands macros, but does |
| 8256 | not parse the result, @var{expression} need not be a valid expression; |
| 8257 | it can be any string of tokens. |
| 8258 | |
| 8259 | @kindex macro exp1 |
| 8260 | @item macro expand-once @var{expression} |
| 8261 | @itemx macro exp1 @var{expression} |
| 8262 | @cindex expand macro once |
| 8263 | @i{(This command is not yet implemented.)} Show the results of |
| 8264 | expanding those preprocessor macro invocations that appear explicitly in |
| 8265 | @var{expression}. Macro invocations appearing in that expansion are |
| 8266 | left unchanged. This command allows you to see the effect of a |
| 8267 | particular macro more clearly, without being confused by further |
| 8268 | expansions. Since @value{GDBN} simply expands macros, but does not |
| 8269 | parse the result, @var{expression} need not be a valid expression; it |
| 8270 | can be any string of tokens. |
| 8271 | |
| 8272 | @kindex info macro |
| 8273 | @cindex macro definition, showing |
| 8274 | @cindex definition, showing a macro's |
| 8275 | @item info macro @var{macro} |
| 8276 | Show the definition of the macro named @var{macro}, and describe the |
| 8277 | source location where that definition was established. |
| 8278 | |
| 8279 | @kindex macro define |
| 8280 | @cindex user-defined macros |
| 8281 | @cindex defining macros interactively |
| 8282 | @cindex macros, user-defined |
| 8283 | @item macro define @var{macro} @var{replacement-list} |
| 8284 | @itemx macro define @var{macro}(@var{arglist}) @var{replacement-list} |
| 8285 | Introduce a definition for a preprocessor macro named @var{macro}, |
| 8286 | invocations of which are replaced by the tokens given in |
| 8287 | @var{replacement-list}. The first form of this command defines an |
| 8288 | ``object-like'' macro, which takes no arguments; the second form |
| 8289 | defines a ``function-like'' macro, which takes the arguments given in |
| 8290 | @var{arglist}. |
| 8291 | |
| 8292 | A definition introduced by this command is in scope in every |
| 8293 | expression evaluated in @value{GDBN}, until it is removed with the |
| 8294 | @code{macro undef} command, described below. The definition overrides |
| 8295 | all definitions for @var{macro} present in the program being debugged, |
| 8296 | as well as any previous user-supplied definition. |
| 8297 | |
| 8298 | @kindex macro undef |
| 8299 | @item macro undef @var{macro} |
| 8300 | Remove any user-supplied definition for the macro named @var{macro}. |
| 8301 | This command only affects definitions provided with the @code{macro |
| 8302 | define} command, described above; it cannot remove definitions present |
| 8303 | in the program being debugged. |
| 8304 | |
| 8305 | @kindex macro list |
| 8306 | @item macro list |
| 8307 | List all the macros defined using the @code{macro define} command. |
| 8308 | @end table |
| 8309 | |
| 8310 | @cindex macros, example of debugging with |
| 8311 | Here is a transcript showing the above commands in action. First, we |
| 8312 | show our source files: |
| 8313 | |
| 8314 | @smallexample |
| 8315 | $ cat sample.c |
| 8316 | #include <stdio.h> |
| 8317 | #include "sample.h" |
| 8318 | |
| 8319 | #define M 42 |
| 8320 | #define ADD(x) (M + x) |
| 8321 | |
| 8322 | main () |
| 8323 | @{ |
| 8324 | #define N 28 |
| 8325 | printf ("Hello, world!\n"); |
| 8326 | #undef N |
| 8327 | printf ("We're so creative.\n"); |
| 8328 | #define N 1729 |
| 8329 | printf ("Goodbye, world!\n"); |
| 8330 | @} |
| 8331 | $ cat sample.h |
| 8332 | #define Q < |
| 8333 | $ |
| 8334 | @end smallexample |
| 8335 | |
| 8336 | Now, we compile the program using the @sc{gnu} C compiler, @value{NGCC}. |
| 8337 | We pass the @option{-gdwarf-2} and @option{-g3} flags to ensure the |
| 8338 | compiler includes information about preprocessor macros in the debugging |
| 8339 | information. |
| 8340 | |
| 8341 | @smallexample |
| 8342 | $ gcc -gdwarf-2 -g3 sample.c -o sample |
| 8343 | $ |
| 8344 | @end smallexample |
| 8345 | |
| 8346 | Now, we start @value{GDBN} on our sample program: |
| 8347 | |
| 8348 | @smallexample |
| 8349 | $ gdb -nw sample |
| 8350 | GNU gdb 2002-05-06-cvs |
| 8351 | Copyright 2002 Free Software Foundation, Inc. |
| 8352 | GDB is free software, @dots{} |
| 8353 | (@value{GDBP}) |
| 8354 | @end smallexample |
| 8355 | |
| 8356 | We can expand macros and examine their definitions, even when the |
| 8357 | program is not running. @value{GDBN} uses the current listing position |
| 8358 | to decide which macro definitions are in scope: |
| 8359 | |
| 8360 | @smallexample |
| 8361 | (@value{GDBP}) list main |
| 8362 | 3 |
| 8363 | 4 #define M 42 |
| 8364 | 5 #define ADD(x) (M + x) |
| 8365 | 6 |
| 8366 | 7 main () |
| 8367 | 8 @{ |
| 8368 | 9 #define N 28 |
| 8369 | 10 printf ("Hello, world!\n"); |
| 8370 | 11 #undef N |
| 8371 | 12 printf ("We're so creative.\n"); |
| 8372 | (@value{GDBP}) info macro ADD |
| 8373 | Defined at /home/jimb/gdb/macros/play/sample.c:5 |
| 8374 | #define ADD(x) (M + x) |
| 8375 | (@value{GDBP}) info macro Q |
| 8376 | Defined at /home/jimb/gdb/macros/play/sample.h:1 |
| 8377 | included at /home/jimb/gdb/macros/play/sample.c:2 |
| 8378 | #define Q < |
| 8379 | (@value{GDBP}) macro expand ADD(1) |
| 8380 | expands to: (42 + 1) |
| 8381 | (@value{GDBP}) macro expand-once ADD(1) |
| 8382 | expands to: once (M + 1) |
| 8383 | (@value{GDBP}) |
| 8384 | @end smallexample |
| 8385 | |
| 8386 | In the example above, note that @code{macro expand-once} expands only |
| 8387 | the macro invocation explicit in the original text --- the invocation of |
| 8388 | @code{ADD} --- but does not expand the invocation of the macro @code{M}, |
| 8389 | which was introduced by @code{ADD}. |
| 8390 | |
| 8391 | Once the program is running, @value{GDBN} uses the macro definitions in |
| 8392 | force at the source line of the current stack frame: |
| 8393 | |
| 8394 | @smallexample |
| 8395 | (@value{GDBP}) break main |
| 8396 | Breakpoint 1 at 0x8048370: file sample.c, line 10. |
| 8397 | (@value{GDBP}) run |
| 8398 | Starting program: /home/jimb/gdb/macros/play/sample |
| 8399 | |
| 8400 | Breakpoint 1, main () at sample.c:10 |
| 8401 | 10 printf ("Hello, world!\n"); |
| 8402 | (@value{GDBP}) |
| 8403 | @end smallexample |
| 8404 | |
| 8405 | At line 10, the definition of the macro @code{N} at line 9 is in force: |
| 8406 | |
| 8407 | @smallexample |
| 8408 | (@value{GDBP}) info macro N |
| 8409 | Defined at /home/jimb/gdb/macros/play/sample.c:9 |
| 8410 | #define N 28 |
| 8411 | (@value{GDBP}) macro expand N Q M |
| 8412 | expands to: 28 < 42 |
| 8413 | (@value{GDBP}) print N Q M |
| 8414 | $1 = 1 |
| 8415 | (@value{GDBP}) |
| 8416 | @end smallexample |
| 8417 | |
| 8418 | As we step over directives that remove @code{N}'s definition, and then |
| 8419 | give it a new definition, @value{GDBN} finds the definition (or lack |
| 8420 | thereof) in force at each point: |
| 8421 | |
| 8422 | @smallexample |
| 8423 | (@value{GDBP}) next |
| 8424 | Hello, world! |
| 8425 | 12 printf ("We're so creative.\n"); |
| 8426 | (@value{GDBP}) info macro N |
| 8427 | The symbol `N' has no definition as a C/C++ preprocessor macro |
| 8428 | at /home/jimb/gdb/macros/play/sample.c:12 |
| 8429 | (@value{GDBP}) next |
| 8430 | We're so creative. |
| 8431 | 14 printf ("Goodbye, world!\n"); |
| 8432 | (@value{GDBP}) info macro N |
| 8433 | Defined at /home/jimb/gdb/macros/play/sample.c:13 |
| 8434 | #define N 1729 |
| 8435 | (@value{GDBP}) macro expand N Q M |
| 8436 | expands to: 1729 < 42 |
| 8437 | (@value{GDBP}) print N Q M |
| 8438 | $2 = 0 |
| 8439 | (@value{GDBP}) |
| 8440 | @end smallexample |
| 8441 | |
| 8442 | |
| 8443 | @node Tracepoints |
| 8444 | @chapter Tracepoints |
| 8445 | @c This chapter is based on the documentation written by Michael |
| 8446 | @c Snyder, David Taylor, Jim Blandy, and Elena Zannoni. |
| 8447 | |
| 8448 | @cindex tracepoints |
| 8449 | In some applications, it is not feasible for the debugger to interrupt |
| 8450 | the program's execution long enough for the developer to learn |
| 8451 | anything helpful about its behavior. If the program's correctness |
| 8452 | depends on its real-time behavior, delays introduced by a debugger |
| 8453 | might cause the program to change its behavior drastically, or perhaps |
| 8454 | fail, even when the code itself is correct. It is useful to be able |
| 8455 | to observe the program's behavior without interrupting it. |
| 8456 | |
| 8457 | Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can |
| 8458 | specify locations in the program, called @dfn{tracepoints}, and |
| 8459 | arbitrary expressions to evaluate when those tracepoints are reached. |
| 8460 | Later, using the @code{tfind} command, you can examine the values |
| 8461 | those expressions had when the program hit the tracepoints. The |
| 8462 | expressions may also denote objects in memory---structures or arrays, |
| 8463 | for example---whose values @value{GDBN} should record; while visiting |
| 8464 | a particular tracepoint, you may inspect those objects as if they were |
| 8465 | in memory at that moment. However, because @value{GDBN} records these |
| 8466 | values without interacting with you, it can do so quickly and |
| 8467 | unobtrusively, hopefully not disturbing the program's behavior. |
| 8468 | |
| 8469 | The tracepoint facility is currently available only for remote |
| 8470 | targets. @xref{Targets}. In addition, your remote target must know |
| 8471 | how to collect trace data. This functionality is implemented in the |
| 8472 | remote stub; however, none of the stubs distributed with @value{GDBN} |
| 8473 | support tracepoints as of this writing. The format of the remote |
| 8474 | packets used to implement tracepoints are described in @ref{Tracepoint |
| 8475 | Packets}. |
| 8476 | |
| 8477 | This chapter describes the tracepoint commands and features. |
| 8478 | |
| 8479 | @menu |
| 8480 | * Set Tracepoints:: |
| 8481 | * Analyze Collected Data:: |
| 8482 | * Tracepoint Variables:: |
| 8483 | @end menu |
| 8484 | |
| 8485 | @node Set Tracepoints |
| 8486 | @section Commands to Set Tracepoints |
| 8487 | |
| 8488 | Before running such a @dfn{trace experiment}, an arbitrary number of |
| 8489 | tracepoints can be set. Like a breakpoint (@pxref{Set Breaks}), a |
| 8490 | tracepoint has a number assigned to it by @value{GDBN}. Like with |
| 8491 | breakpoints, tracepoint numbers are successive integers starting from |
| 8492 | one. Many of the commands associated with tracepoints take the |
| 8493 | tracepoint number as their argument, to identify which tracepoint to |
| 8494 | work on. |
| 8495 | |
| 8496 | For each tracepoint, you can specify, in advance, some arbitrary set |
| 8497 | of data that you want the target to collect in the trace buffer when |
| 8498 | it hits that tracepoint. The collected data can include registers, |
| 8499 | local variables, or global data. Later, you can use @value{GDBN} |
| 8500 | commands to examine the values these data had at the time the |
| 8501 | tracepoint was hit. |
| 8502 | |
| 8503 | This section describes commands to set tracepoints and associated |
| 8504 | conditions and actions. |
| 8505 | |
| 8506 | @menu |
| 8507 | * Create and Delete Tracepoints:: |
| 8508 | * Enable and Disable Tracepoints:: |
| 8509 | * Tracepoint Passcounts:: |
| 8510 | * Tracepoint Actions:: |
| 8511 | * Listing Tracepoints:: |
| 8512 | * Starting and Stopping Trace Experiments:: |
| 8513 | @end menu |
| 8514 | |
| 8515 | @node Create and Delete Tracepoints |
| 8516 | @subsection Create and Delete Tracepoints |
| 8517 | |
| 8518 | @table @code |
| 8519 | @cindex set tracepoint |
| 8520 | @kindex trace |
| 8521 | @item trace |
| 8522 | The @code{trace} command is very similar to the @code{break} command. |
| 8523 | Its argument can be a source line, a function name, or an address in |
| 8524 | the target program. @xref{Set Breaks}. The @code{trace} command |
| 8525 | defines a tracepoint, which is a point in the target program where the |
| 8526 | debugger will briefly stop, collect some data, and then allow the |
| 8527 | program to continue. Setting a tracepoint or changing its commands |
| 8528 | doesn't take effect until the next @code{tstart} command; thus, you |
| 8529 | cannot change the tracepoint attributes once a trace experiment is |
| 8530 | running. |
| 8531 | |
| 8532 | Here are some examples of using the @code{trace} command: |
| 8533 | |
| 8534 | @smallexample |
| 8535 | (@value{GDBP}) @b{trace foo.c:121} // a source file and line number |
| 8536 | |
| 8537 | (@value{GDBP}) @b{trace +2} // 2 lines forward |
| 8538 | |
| 8539 | (@value{GDBP}) @b{trace my_function} // first source line of function |
| 8540 | |
| 8541 | (@value{GDBP}) @b{trace *my_function} // EXACT start address of function |
| 8542 | |
| 8543 | (@value{GDBP}) @b{trace *0x2117c4} // an address |
| 8544 | @end smallexample |
| 8545 | |
| 8546 | @noindent |
| 8547 | You can abbreviate @code{trace} as @code{tr}. |
| 8548 | |
| 8549 | @vindex $tpnum |
| 8550 | @cindex last tracepoint number |
| 8551 | @cindex recent tracepoint number |
| 8552 | @cindex tracepoint number |
| 8553 | The convenience variable @code{$tpnum} records the tracepoint number |
| 8554 | of the most recently set tracepoint. |
| 8555 | |
| 8556 | @kindex delete tracepoint |
| 8557 | @cindex tracepoint deletion |
| 8558 | @item delete tracepoint @r{[}@var{num}@r{]} |
| 8559 | Permanently delete one or more tracepoints. With no argument, the |
| 8560 | default is to delete all tracepoints. |
| 8561 | |
| 8562 | Examples: |
| 8563 | |
| 8564 | @smallexample |
| 8565 | (@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints |
| 8566 | |
| 8567 | (@value{GDBP}) @b{delete trace} // remove all tracepoints |
| 8568 | @end smallexample |
| 8569 | |
| 8570 | @noindent |
| 8571 | You can abbreviate this command as @code{del tr}. |
| 8572 | @end table |
| 8573 | |
| 8574 | @node Enable and Disable Tracepoints |
| 8575 | @subsection Enable and Disable Tracepoints |
| 8576 | |
| 8577 | @table @code |
| 8578 | @kindex disable tracepoint |
| 8579 | @item disable tracepoint @r{[}@var{num}@r{]} |
| 8580 | Disable tracepoint @var{num}, or all tracepoints if no argument |
| 8581 | @var{num} is given. A disabled tracepoint will have no effect during |
| 8582 | the next trace experiment, but it is not forgotten. You can re-enable |
| 8583 | a disabled tracepoint using the @code{enable tracepoint} command. |
| 8584 | |
| 8585 | @kindex enable tracepoint |
| 8586 | @item enable tracepoint @r{[}@var{num}@r{]} |
| 8587 | Enable tracepoint @var{num}, or all tracepoints. The enabled |
| 8588 | tracepoints will become effective the next time a trace experiment is |
| 8589 | run. |
| 8590 | @end table |
| 8591 | |
| 8592 | @node Tracepoint Passcounts |
| 8593 | @subsection Tracepoint Passcounts |
| 8594 | |
| 8595 | @table @code |
| 8596 | @kindex passcount |
| 8597 | @cindex tracepoint pass count |
| 8598 | @item passcount @r{[}@var{n} @r{[}@var{num}@r{]]} |
| 8599 | Set the @dfn{passcount} of a tracepoint. The passcount is a way to |
| 8600 | automatically stop a trace experiment. If a tracepoint's passcount is |
| 8601 | @var{n}, then the trace experiment will be automatically stopped on |
| 8602 | the @var{n}'th time that tracepoint is hit. If the tracepoint number |
| 8603 | @var{num} is not specified, the @code{passcount} command sets the |
| 8604 | passcount of the most recently defined tracepoint. If no passcount is |
| 8605 | given, the trace experiment will run until stopped explicitly by the |
| 8606 | user. |
| 8607 | |
| 8608 | Examples: |
| 8609 | |
| 8610 | @smallexample |
| 8611 | (@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of |
| 8612 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2} |
| 8613 | |
| 8614 | (@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the |
| 8615 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.} |
| 8616 | (@value{GDBP}) @b{trace foo} |
| 8617 | (@value{GDBP}) @b{pass 3} |
| 8618 | (@value{GDBP}) @b{trace bar} |
| 8619 | (@value{GDBP}) @b{pass 2} |
| 8620 | (@value{GDBP}) @b{trace baz} |
| 8621 | (@value{GDBP}) @b{pass 1} // Stop tracing when foo has been |
| 8622 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has} |
| 8623 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times} |
| 8624 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.} |
| 8625 | @end smallexample |
| 8626 | @end table |
| 8627 | |
| 8628 | @node Tracepoint Actions |
| 8629 | @subsection Tracepoint Action Lists |
| 8630 | |
| 8631 | @table @code |
| 8632 | @kindex actions |
| 8633 | @cindex tracepoint actions |
| 8634 | @item actions @r{[}@var{num}@r{]} |
| 8635 | This command will prompt for a list of actions to be taken when the |
| 8636 | tracepoint is hit. If the tracepoint number @var{num} is not |
| 8637 | specified, this command sets the actions for the one that was most |
| 8638 | recently defined (so that you can define a tracepoint and then say |
| 8639 | @code{actions} without bothering about its number). You specify the |
| 8640 | actions themselves on the following lines, one action at a time, and |
| 8641 | terminate the actions list with a line containing just @code{end}. So |
| 8642 | far, the only defined actions are @code{collect} and |
| 8643 | @code{while-stepping}. |
| 8644 | |
| 8645 | @cindex remove actions from a tracepoint |
| 8646 | To remove all actions from a tracepoint, type @samp{actions @var{num}} |
| 8647 | and follow it immediately with @samp{end}. |
| 8648 | |
| 8649 | @smallexample |
| 8650 | (@value{GDBP}) @b{collect @var{data}} // collect some data |
| 8651 | |
| 8652 | (@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data |
| 8653 | |
| 8654 | (@value{GDBP}) @b{end} // signals the end of actions. |
| 8655 | @end smallexample |
| 8656 | |
| 8657 | In the following example, the action list begins with @code{collect} |
| 8658 | commands indicating the things to be collected when the tracepoint is |
| 8659 | hit. Then, in order to single-step and collect additional data |
| 8660 | following the tracepoint, a @code{while-stepping} command is used, |
| 8661 | followed by the list of things to be collected while stepping. The |
| 8662 | @code{while-stepping} command is terminated by its own separate |
| 8663 | @code{end} command. Lastly, the action list is terminated by an |
| 8664 | @code{end} command. |
| 8665 | |
| 8666 | @smallexample |
| 8667 | (@value{GDBP}) @b{trace foo} |
| 8668 | (@value{GDBP}) @b{actions} |
| 8669 | Enter actions for tracepoint 1, one per line: |
| 8670 | > collect bar,baz |
| 8671 | > collect $regs |
| 8672 | > while-stepping 12 |
| 8673 | > collect $fp, $sp |
| 8674 | > end |
| 8675 | end |
| 8676 | @end smallexample |
| 8677 | |
| 8678 | @kindex collect @r{(tracepoints)} |
| 8679 | @item collect @var{expr1}, @var{expr2}, @dots{} |
| 8680 | Collect values of the given expressions when the tracepoint is hit. |
| 8681 | This command accepts a comma-separated list of any valid expressions. |
| 8682 | In addition to global, static, or local variables, the following |
| 8683 | special arguments are supported: |
| 8684 | |
| 8685 | @table @code |
| 8686 | @item $regs |
| 8687 | collect all registers |
| 8688 | |
| 8689 | @item $args |
| 8690 | collect all function arguments |
| 8691 | |
| 8692 | @item $locals |
| 8693 | collect all local variables. |
| 8694 | @end table |
| 8695 | |
| 8696 | You can give several consecutive @code{collect} commands, each one |
| 8697 | with a single argument, or one @code{collect} command with several |
| 8698 | arguments separated by commas: the effect is the same. |
| 8699 | |
| 8700 | The command @code{info scope} (@pxref{Symbols, info scope}) is |
| 8701 | particularly useful for figuring out what data to collect. |
| 8702 | |
| 8703 | @kindex while-stepping @r{(tracepoints)} |
| 8704 | @item while-stepping @var{n} |
| 8705 | Perform @var{n} single-step traces after the tracepoint, collecting |
| 8706 | new data at each step. The @code{while-stepping} command is |
| 8707 | followed by the list of what to collect while stepping (followed by |
| 8708 | its own @code{end} command): |
| 8709 | |
| 8710 | @smallexample |
| 8711 | > while-stepping 12 |
| 8712 | > collect $regs, myglobal |
| 8713 | > end |
| 8714 | > |
| 8715 | @end smallexample |
| 8716 | |
| 8717 | @noindent |
| 8718 | You may abbreviate @code{while-stepping} as @code{ws} or |
| 8719 | @code{stepping}. |
| 8720 | @end table |
| 8721 | |
| 8722 | @node Listing Tracepoints |
| 8723 | @subsection Listing Tracepoints |
| 8724 | |
| 8725 | @table @code |
| 8726 | @kindex info tracepoints |
| 8727 | @kindex info tp |
| 8728 | @cindex information about tracepoints |
| 8729 | @item info tracepoints @r{[}@var{num}@r{]} |
| 8730 | Display information about the tracepoint @var{num}. If you don't specify |
| 8731 | a tracepoint number, displays information about all the tracepoints |
| 8732 | defined so far. For each tracepoint, the following information is |
| 8733 | shown: |
| 8734 | |
| 8735 | @itemize @bullet |
| 8736 | @item |
| 8737 | its number |
| 8738 | @item |
| 8739 | whether it is enabled or disabled |
| 8740 | @item |
| 8741 | its address |
| 8742 | @item |
| 8743 | its passcount as given by the @code{passcount @var{n}} command |
| 8744 | @item |
| 8745 | its step count as given by the @code{while-stepping @var{n}} command |
| 8746 | @item |
| 8747 | where in the source files is the tracepoint set |
| 8748 | @item |
| 8749 | its action list as given by the @code{actions} command |
| 8750 | @end itemize |
| 8751 | |
| 8752 | @smallexample |
| 8753 | (@value{GDBP}) @b{info trace} |
| 8754 | Num Enb Address PassC StepC What |
| 8755 | 1 y 0x002117c4 0 0 <gdb_asm> |
| 8756 | 2 y 0x0020dc64 0 0 in g_test at g_test.c:1375 |
| 8757 | 3 y 0x0020b1f4 0 0 in get_data at ../foo.c:41 |
| 8758 | (@value{GDBP}) |
| 8759 | @end smallexample |
| 8760 | |
| 8761 | @noindent |
| 8762 | This command can be abbreviated @code{info tp}. |
| 8763 | @end table |
| 8764 | |
| 8765 | @node Starting and Stopping Trace Experiments |
| 8766 | @subsection Starting and Stopping Trace Experiments |
| 8767 | |
| 8768 | @table @code |
| 8769 | @kindex tstart |
| 8770 | @cindex start a new trace experiment |
| 8771 | @cindex collected data discarded |
| 8772 | @item tstart |
| 8773 | This command takes no arguments. It starts the trace experiment, and |
| 8774 | begins collecting data. This has the side effect of discarding all |
| 8775 | the data collected in the trace buffer during the previous trace |
| 8776 | experiment. |
| 8777 | |
| 8778 | @kindex tstop |
| 8779 | @cindex stop a running trace experiment |
| 8780 | @item tstop |
| 8781 | This command takes no arguments. It ends the trace experiment, and |
| 8782 | stops collecting data. |
| 8783 | |
| 8784 | @strong{Note}: a trace experiment and data collection may stop |
| 8785 | automatically if any tracepoint's passcount is reached |
| 8786 | (@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full. |
| 8787 | |
| 8788 | @kindex tstatus |
| 8789 | @cindex status of trace data collection |
| 8790 | @cindex trace experiment, status of |
| 8791 | @item tstatus |
| 8792 | This command displays the status of the current trace data |
| 8793 | collection. |
| 8794 | @end table |
| 8795 | |
| 8796 | Here is an example of the commands we described so far: |
| 8797 | |
| 8798 | @smallexample |
| 8799 | (@value{GDBP}) @b{trace gdb_c_test} |
| 8800 | (@value{GDBP}) @b{actions} |
| 8801 | Enter actions for tracepoint #1, one per line. |
| 8802 | > collect $regs,$locals,$args |
| 8803 | > while-stepping 11 |
| 8804 | > collect $regs |
| 8805 | > end |
| 8806 | > end |
| 8807 | (@value{GDBP}) @b{tstart} |
| 8808 | [time passes @dots{}] |
| 8809 | (@value{GDBP}) @b{tstop} |
| 8810 | @end smallexample |
| 8811 | |
| 8812 | |
| 8813 | @node Analyze Collected Data |
| 8814 | @section Using the Collected Data |
| 8815 | |
| 8816 | After the tracepoint experiment ends, you use @value{GDBN} commands |
| 8817 | for examining the trace data. The basic idea is that each tracepoint |
| 8818 | collects a trace @dfn{snapshot} every time it is hit and another |
| 8819 | snapshot every time it single-steps. All these snapshots are |
| 8820 | consecutively numbered from zero and go into a buffer, and you can |
| 8821 | examine them later. The way you examine them is to @dfn{focus} on a |
| 8822 | specific trace snapshot. When the remote stub is focused on a trace |
| 8823 | snapshot, it will respond to all @value{GDBN} requests for memory and |
| 8824 | registers by reading from the buffer which belongs to that snapshot, |
| 8825 | rather than from @emph{real} memory or registers of the program being |
| 8826 | debugged. This means that @strong{all} @value{GDBN} commands |
| 8827 | (@code{print}, @code{info registers}, @code{backtrace}, etc.) will |
| 8828 | behave as if we were currently debugging the program state as it was |
| 8829 | when the tracepoint occurred. Any requests for data that are not in |
| 8830 | the buffer will fail. |
| 8831 | |
| 8832 | @menu |
| 8833 | * tfind:: How to select a trace snapshot |
| 8834 | * tdump:: How to display all data for a snapshot |
| 8835 | * save-tracepoints:: How to save tracepoints for a future run |
| 8836 | @end menu |
| 8837 | |
| 8838 | @node tfind |
| 8839 | @subsection @code{tfind @var{n}} |
| 8840 | |
| 8841 | @kindex tfind |
| 8842 | @cindex select trace snapshot |
| 8843 | @cindex find trace snapshot |
| 8844 | The basic command for selecting a trace snapshot from the buffer is |
| 8845 | @code{tfind @var{n}}, which finds trace snapshot number @var{n}, |
| 8846 | counting from zero. If no argument @var{n} is given, the next |
| 8847 | snapshot is selected. |
| 8848 | |
| 8849 | Here are the various forms of using the @code{tfind} command. |
| 8850 | |
| 8851 | @table @code |
| 8852 | @item tfind start |
| 8853 | Find the first snapshot in the buffer. This is a synonym for |
| 8854 | @code{tfind 0} (since 0 is the number of the first snapshot). |
| 8855 | |
| 8856 | @item tfind none |
| 8857 | Stop debugging trace snapshots, resume @emph{live} debugging. |
| 8858 | |
| 8859 | @item tfind end |
| 8860 | Same as @samp{tfind none}. |
| 8861 | |
| 8862 | @item tfind |
| 8863 | No argument means find the next trace snapshot. |
| 8864 | |
| 8865 | @item tfind - |
| 8866 | Find the previous trace snapshot before the current one. This permits |
| 8867 | retracing earlier steps. |
| 8868 | |
| 8869 | @item tfind tracepoint @var{num} |
| 8870 | Find the next snapshot associated with tracepoint @var{num}. Search |
| 8871 | proceeds forward from the last examined trace snapshot. If no |
| 8872 | argument @var{num} is given, it means find the next snapshot collected |
| 8873 | for the same tracepoint as the current snapshot. |
| 8874 | |
| 8875 | @item tfind pc @var{addr} |
| 8876 | Find the next snapshot associated with the value @var{addr} of the |
| 8877 | program counter. Search proceeds forward from the last examined trace |
| 8878 | snapshot. If no argument @var{addr} is given, it means find the next |
| 8879 | snapshot with the same value of PC as the current snapshot. |
| 8880 | |
| 8881 | @item tfind outside @var{addr1}, @var{addr2} |
| 8882 | Find the next snapshot whose PC is outside the given range of |
| 8883 | addresses. |
| 8884 | |
| 8885 | @item tfind range @var{addr1}, @var{addr2} |
| 8886 | Find the next snapshot whose PC is between @var{addr1} and |
| 8887 | @var{addr2}. @c FIXME: Is the range inclusive or exclusive? |
| 8888 | |
| 8889 | @item tfind line @r{[}@var{file}:@r{]}@var{n} |
| 8890 | Find the next snapshot associated with the source line @var{n}. If |
| 8891 | the optional argument @var{file} is given, refer to line @var{n} in |
| 8892 | that source file. Search proceeds forward from the last examined |
| 8893 | trace snapshot. If no argument @var{n} is given, it means find the |
| 8894 | next line other than the one currently being examined; thus saying |
| 8895 | @code{tfind line} repeatedly can appear to have the same effect as |
| 8896 | stepping from line to line in a @emph{live} debugging session. |
| 8897 | @end table |
| 8898 | |
| 8899 | The default arguments for the @code{tfind} commands are specifically |
| 8900 | designed to make it easy to scan through the trace buffer. For |
| 8901 | instance, @code{tfind} with no argument selects the next trace |
| 8902 | snapshot, and @code{tfind -} with no argument selects the previous |
| 8903 | trace snapshot. So, by giving one @code{tfind} command, and then |
| 8904 | simply hitting @key{RET} repeatedly you can examine all the trace |
| 8905 | snapshots in order. Or, by saying @code{tfind -} and then hitting |
| 8906 | @key{RET} repeatedly you can examine the snapshots in reverse order. |
| 8907 | The @code{tfind line} command with no argument selects the snapshot |
| 8908 | for the next source line executed. The @code{tfind pc} command with |
| 8909 | no argument selects the next snapshot with the same program counter |
| 8910 | (PC) as the current frame. The @code{tfind tracepoint} command with |
| 8911 | no argument selects the next trace snapshot collected by the same |
| 8912 | tracepoint as the current one. |
| 8913 | |
| 8914 | In addition to letting you scan through the trace buffer manually, |
| 8915 | these commands make it easy to construct @value{GDBN} scripts that |
| 8916 | scan through the trace buffer and print out whatever collected data |
| 8917 | you are interested in. Thus, if we want to examine the PC, FP, and SP |
| 8918 | registers from each trace frame in the buffer, we can say this: |
| 8919 | |
| 8920 | @smallexample |
| 8921 | (@value{GDBP}) @b{tfind start} |
| 8922 | (@value{GDBP}) @b{while ($trace_frame != -1)} |
| 8923 | > printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \ |
| 8924 | $trace_frame, $pc, $sp, $fp |
| 8925 | > tfind |
| 8926 | > end |
| 8927 | |
| 8928 | Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44 |
| 8929 | Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44 |
| 8930 | Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44 |
| 8931 | Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44 |
| 8932 | Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44 |
| 8933 | Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44 |
| 8934 | Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44 |
| 8935 | Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44 |
| 8936 | Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44 |
| 8937 | Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44 |
| 8938 | Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14 |
| 8939 | @end smallexample |
| 8940 | |
| 8941 | Or, if we want to examine the variable @code{X} at each source line in |
| 8942 | the buffer: |
| 8943 | |
| 8944 | @smallexample |
| 8945 | (@value{GDBP}) @b{tfind start} |
| 8946 | (@value{GDBP}) @b{while ($trace_frame != -1)} |
| 8947 | > printf "Frame %d, X == %d\n", $trace_frame, X |
| 8948 | > tfind line |
| 8949 | > end |
| 8950 | |
| 8951 | Frame 0, X = 1 |
| 8952 | Frame 7, X = 2 |
| 8953 | Frame 13, X = 255 |
| 8954 | @end smallexample |
| 8955 | |
| 8956 | @node tdump |
| 8957 | @subsection @code{tdump} |
| 8958 | @kindex tdump |
| 8959 | @cindex dump all data collected at tracepoint |
| 8960 | @cindex tracepoint data, display |
| 8961 | |
| 8962 | This command takes no arguments. It prints all the data collected at |
| 8963 | the current trace snapshot. |
| 8964 | |
| 8965 | @smallexample |
| 8966 | (@value{GDBP}) @b{trace 444} |
| 8967 | (@value{GDBP}) @b{actions} |
| 8968 | Enter actions for tracepoint #2, one per line: |
| 8969 | > collect $regs, $locals, $args, gdb_long_test |
| 8970 | > end |
| 8971 | |
| 8972 | (@value{GDBP}) @b{tstart} |
| 8973 | |
| 8974 | (@value{GDBP}) @b{tfind line 444} |
| 8975 | #0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66) |
| 8976 | at gdb_test.c:444 |
| 8977 | 444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", ) |
| 8978 | |
| 8979 | (@value{GDBP}) @b{tdump} |
| 8980 | Data collected at tracepoint 2, trace frame 1: |
| 8981 | d0 0xc4aa0085 -995491707 |
| 8982 | d1 0x18 24 |
| 8983 | d2 0x80 128 |
| 8984 | d3 0x33 51 |
| 8985 | d4 0x71aea3d 119204413 |
| 8986 | d5 0x22 34 |
| 8987 | d6 0xe0 224 |
| 8988 | d7 0x380035 3670069 |
| 8989 | a0 0x19e24a 1696330 |
| 8990 | a1 0x3000668 50333288 |
| 8991 | a2 0x100 256 |
| 8992 | a3 0x322000 3284992 |
| 8993 | a4 0x3000698 50333336 |
| 8994 | a5 0x1ad3cc 1758156 |
| 8995 | fp 0x30bf3c 0x30bf3c |
| 8996 | sp 0x30bf34 0x30bf34 |
| 8997 | ps 0x0 0 |
| 8998 | pc 0x20b2c8 0x20b2c8 |
| 8999 | fpcontrol 0x0 0 |
| 9000 | fpstatus 0x0 0 |
| 9001 | fpiaddr 0x0 0 |
| 9002 | p = 0x20e5b4 "gdb-test" |
| 9003 | p1 = (void *) 0x11 |
| 9004 | p2 = (void *) 0x22 |
| 9005 | p3 = (void *) 0x33 |
| 9006 | p4 = (void *) 0x44 |
| 9007 | p5 = (void *) 0x55 |
| 9008 | p6 = (void *) 0x66 |
| 9009 | gdb_long_test = 17 '\021' |
| 9010 | |
| 9011 | (@value{GDBP}) |
| 9012 | @end smallexample |
| 9013 | |
| 9014 | @node save-tracepoints |
| 9015 | @subsection @code{save-tracepoints @var{filename}} |
| 9016 | @kindex save-tracepoints |
| 9017 | @cindex save tracepoints for future sessions |
| 9018 | |
| 9019 | This command saves all current tracepoint definitions together with |
| 9020 | their actions and passcounts, into a file @file{@var{filename}} |
| 9021 | suitable for use in a later debugging session. To read the saved |
| 9022 | tracepoint definitions, use the @code{source} command (@pxref{Command |
| 9023 | Files}). |
| 9024 | |
| 9025 | @node Tracepoint Variables |
| 9026 | @section Convenience Variables for Tracepoints |
| 9027 | @cindex tracepoint variables |
| 9028 | @cindex convenience variables for tracepoints |
| 9029 | |
| 9030 | @table @code |
| 9031 | @vindex $trace_frame |
| 9032 | @item (int) $trace_frame |
| 9033 | The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no |
| 9034 | snapshot is selected. |
| 9035 | |
| 9036 | @vindex $tracepoint |
| 9037 | @item (int) $tracepoint |
| 9038 | The tracepoint for the current trace snapshot. |
| 9039 | |
| 9040 | @vindex $trace_line |
| 9041 | @item (int) $trace_line |
| 9042 | The line number for the current trace snapshot. |
| 9043 | |
| 9044 | @vindex $trace_file |
| 9045 | @item (char []) $trace_file |
| 9046 | The source file for the current trace snapshot. |
| 9047 | |
| 9048 | @vindex $trace_func |
| 9049 | @item (char []) $trace_func |
| 9050 | The name of the function containing @code{$tracepoint}. |
| 9051 | @end table |
| 9052 | |
| 9053 | Note: @code{$trace_file} is not suitable for use in @code{printf}, |
| 9054 | use @code{output} instead. |
| 9055 | |
| 9056 | Here's a simple example of using these convenience variables for |
| 9057 | stepping through all the trace snapshots and printing some of their |
| 9058 | data. |
| 9059 | |
| 9060 | @smallexample |
| 9061 | (@value{GDBP}) @b{tfind start} |
| 9062 | |
| 9063 | (@value{GDBP}) @b{while $trace_frame != -1} |
| 9064 | > output $trace_file |
| 9065 | > printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint |
| 9066 | > tfind |
| 9067 | > end |
| 9068 | @end smallexample |
| 9069 | |
| 9070 | @node Overlays |
| 9071 | @chapter Debugging Programs That Use Overlays |
| 9072 | @cindex overlays |
| 9073 | |
| 9074 | If your program is too large to fit completely in your target system's |
| 9075 | memory, you can sometimes use @dfn{overlays} to work around this |
| 9076 | problem. @value{GDBN} provides some support for debugging programs that |
| 9077 | use overlays. |
| 9078 | |
| 9079 | @menu |
| 9080 | * How Overlays Work:: A general explanation of overlays. |
| 9081 | * Overlay Commands:: Managing overlays in @value{GDBN}. |
| 9082 | * Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are |
| 9083 | mapped by asking the inferior. |
| 9084 | * Overlay Sample Program:: A sample program using overlays. |
| 9085 | @end menu |
| 9086 | |
| 9087 | @node How Overlays Work |
| 9088 | @section How Overlays Work |
| 9089 | @cindex mapped overlays |
| 9090 | @cindex unmapped overlays |
| 9091 | @cindex load address, overlay's |
| 9092 | @cindex mapped address |
| 9093 | @cindex overlay area |
| 9094 | |
| 9095 | Suppose you have a computer whose instruction address space is only 64 |
| 9096 | kilobytes long, but which has much more memory which can be accessed by |
| 9097 | other means: special instructions, segment registers, or memory |
| 9098 | management hardware, for example. Suppose further that you want to |
| 9099 | adapt a program which is larger than 64 kilobytes to run on this system. |
| 9100 | |
| 9101 | One solution is to identify modules of your program which are relatively |
| 9102 | independent, and need not call each other directly; call these modules |
| 9103 | @dfn{overlays}. Separate the overlays from the main program, and place |
| 9104 | their machine code in the larger memory. Place your main program in |
| 9105 | instruction memory, but leave at least enough space there to hold the |
| 9106 | largest overlay as well. |
| 9107 | |
| 9108 | Now, to call a function located in an overlay, you must first copy that |
| 9109 | overlay's machine code from the large memory into the space set aside |
| 9110 | for it in the instruction memory, and then jump to its entry point |
| 9111 | there. |
| 9112 | |
| 9113 | @c NB: In the below the mapped area's size is greater or equal to the |
| 9114 | @c size of all overlays. This is intentional to remind the developer |
| 9115 | @c that overlays don't necessarily need to be the same size. |
| 9116 | |
| 9117 | @smallexample |
| 9118 | @group |
| 9119 | Data Instruction Larger |
| 9120 | Address Space Address Space Address Space |
| 9121 | +-----------+ +-----------+ +-----------+ |
| 9122 | | | | | | | |
| 9123 | +-----------+ +-----------+ +-----------+<-- overlay 1 |
| 9124 | | program | | main | .----| overlay 1 | load address |
| 9125 | | variables | | program | | +-----------+ |
| 9126 | | and heap | | | | | | |
| 9127 | +-----------+ | | | +-----------+<-- overlay 2 |
| 9128 | | | +-----------+ | | | load address |
| 9129 | +-----------+ | | | .-| overlay 2 | |
| 9130 | | | | | | | |
| 9131 | mapped --->+-----------+ | | +-----------+ |
| 9132 | address | | | | | | |
| 9133 | | overlay | <-' | | | |
| 9134 | | area | <---' +-----------+<-- overlay 3 |
| 9135 | | | <---. | | load address |
| 9136 | +-----------+ `--| overlay 3 | |
| 9137 | | | | | |
| 9138 | +-----------+ | | |
| 9139 | +-----------+ |
| 9140 | | | |
| 9141 | +-----------+ |
| 9142 | |
| 9143 | @anchor{A code overlay}A code overlay |
| 9144 | @end group |
| 9145 | @end smallexample |
| 9146 | |
| 9147 | The diagram (@pxref{A code overlay}) shows a system with separate data |
| 9148 | and instruction address spaces. To map an overlay, the program copies |
| 9149 | its code from the larger address space to the instruction address space. |
| 9150 | Since the overlays shown here all use the same mapped address, only one |
| 9151 | may be mapped at a time. For a system with a single address space for |
| 9152 | data and instructions, the diagram would be similar, except that the |
| 9153 | program variables and heap would share an address space with the main |
| 9154 | program and the overlay area. |
| 9155 | |
| 9156 | An overlay loaded into instruction memory and ready for use is called a |
| 9157 | @dfn{mapped} overlay; its @dfn{mapped address} is its address in the |
| 9158 | instruction memory. An overlay not present (or only partially present) |
| 9159 | in instruction memory is called @dfn{unmapped}; its @dfn{load address} |
| 9160 | is its address in the larger memory. The mapped address is also called |
| 9161 | the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also |
| 9162 | called the @dfn{load memory address}, or @dfn{LMA}. |
| 9163 | |
| 9164 | Unfortunately, overlays are not a completely transparent way to adapt a |
| 9165 | program to limited instruction memory. They introduce a new set of |
| 9166 | global constraints you must keep in mind as you design your program: |
| 9167 | |
| 9168 | @itemize @bullet |
| 9169 | |
| 9170 | @item |
| 9171 | Before calling or returning to a function in an overlay, your program |
| 9172 | must make sure that overlay is actually mapped. Otherwise, the call or |
| 9173 | return will transfer control to the right address, but in the wrong |
| 9174 | overlay, and your program will probably crash. |
| 9175 | |
| 9176 | @item |
| 9177 | If the process of mapping an overlay is expensive on your system, you |
| 9178 | will need to choose your overlays carefully to minimize their effect on |
| 9179 | your program's performance. |
| 9180 | |
| 9181 | @item |
| 9182 | The executable file you load onto your system must contain each |
| 9183 | overlay's instructions, appearing at the overlay's load address, not its |
| 9184 | mapped address. However, each overlay's instructions must be relocated |
| 9185 | and its symbols defined as if the overlay were at its mapped address. |
| 9186 | You can use GNU linker scripts to specify different load and relocation |
| 9187 | addresses for pieces of your program; see @ref{Overlay Description,,, |
| 9188 | ld.info, Using ld: the GNU linker}. |
| 9189 | |
| 9190 | @item |
| 9191 | The procedure for loading executable files onto your system must be able |
| 9192 | to load their contents into the larger address space as well as the |
| 9193 | instruction and data spaces. |
| 9194 | |
| 9195 | @end itemize |
| 9196 | |
| 9197 | The overlay system described above is rather simple, and could be |
| 9198 | improved in many ways: |
| 9199 | |
| 9200 | @itemize @bullet |
| 9201 | |
| 9202 | @item |
| 9203 | If your system has suitable bank switch registers or memory management |
| 9204 | hardware, you could use those facilities to make an overlay's load area |
| 9205 | contents simply appear at their mapped address in instruction space. |
| 9206 | This would probably be faster than copying the overlay to its mapped |
| 9207 | area in the usual way. |
| 9208 | |
| 9209 | @item |
| 9210 | If your overlays are small enough, you could set aside more than one |
| 9211 | overlay area, and have more than one overlay mapped at a time. |
| 9212 | |
| 9213 | @item |
| 9214 | You can use overlays to manage data, as well as instructions. In |
| 9215 | general, data overlays are even less transparent to your design than |
| 9216 | code overlays: whereas code overlays only require care when you call or |
| 9217 | return to functions, data overlays require care every time you access |
| 9218 | the data. Also, if you change the contents of a data overlay, you |
| 9219 | must copy its contents back out to its load address before you can copy a |
| 9220 | different data overlay into the same mapped area. |
| 9221 | |
| 9222 | @end itemize |
| 9223 | |
| 9224 | |
| 9225 | @node Overlay Commands |
| 9226 | @section Overlay Commands |
| 9227 | |
| 9228 | To use @value{GDBN}'s overlay support, each overlay in your program must |
| 9229 | correspond to a separate section of the executable file. The section's |
| 9230 | virtual memory address and load memory address must be the overlay's |
| 9231 | mapped and load addresses. Identifying overlays with sections allows |
| 9232 | @value{GDBN} to determine the appropriate address of a function or |
| 9233 | variable, depending on whether the overlay is mapped or not. |
| 9234 | |
| 9235 | @value{GDBN}'s overlay commands all start with the word @code{overlay}; |
| 9236 | you can abbreviate this as @code{ov} or @code{ovly}. The commands are: |
| 9237 | |
| 9238 | @table @code |
| 9239 | @item overlay off |
| 9240 | @kindex overlay |
| 9241 | Disable @value{GDBN}'s overlay support. When overlay support is |
| 9242 | disabled, @value{GDBN} assumes that all functions and variables are |
| 9243 | always present at their mapped addresses. By default, @value{GDBN}'s |
| 9244 | overlay support is disabled. |
| 9245 | |
| 9246 | @item overlay manual |
| 9247 | @cindex manual overlay debugging |
| 9248 | Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN} |
| 9249 | relies on you to tell it which overlays are mapped, and which are not, |
| 9250 | using the @code{overlay map-overlay} and @code{overlay unmap-overlay} |
| 9251 | commands described below. |
| 9252 | |
| 9253 | @item overlay map-overlay @var{overlay} |
| 9254 | @itemx overlay map @var{overlay} |
| 9255 | @cindex map an overlay |
| 9256 | Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must |
| 9257 | be the name of the object file section containing the overlay. When an |
| 9258 | overlay is mapped, @value{GDBN} assumes it can find the overlay's |
| 9259 | functions and variables at their mapped addresses. @value{GDBN} assumes |
| 9260 | that any other overlays whose mapped ranges overlap that of |
| 9261 | @var{overlay} are now unmapped. |
| 9262 | |
| 9263 | @item overlay unmap-overlay @var{overlay} |
| 9264 | @itemx overlay unmap @var{overlay} |
| 9265 | @cindex unmap an overlay |
| 9266 | Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay} |
| 9267 | must be the name of the object file section containing the overlay. |
| 9268 | When an overlay is unmapped, @value{GDBN} assumes it can find the |
| 9269 | overlay's functions and variables at their load addresses. |
| 9270 | |
| 9271 | @item overlay auto |
| 9272 | Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN} |
| 9273 | consults a data structure the overlay manager maintains in the inferior |
| 9274 | to see which overlays are mapped. For details, see @ref{Automatic |
| 9275 | Overlay Debugging}. |
| 9276 | |
| 9277 | @item overlay load-target |
| 9278 | @itemx overlay load |
| 9279 | @cindex reloading the overlay table |
| 9280 | Re-read the overlay table from the inferior. Normally, @value{GDBN} |
| 9281 | re-reads the table @value{GDBN} automatically each time the inferior |
| 9282 | stops, so this command should only be necessary if you have changed the |
| 9283 | overlay mapping yourself using @value{GDBN}. This command is only |
| 9284 | useful when using automatic overlay debugging. |
| 9285 | |
| 9286 | @item overlay list-overlays |
| 9287 | @itemx overlay list |
| 9288 | @cindex listing mapped overlays |
| 9289 | Display a list of the overlays currently mapped, along with their mapped |
| 9290 | addresses, load addresses, and sizes. |
| 9291 | |
| 9292 | @end table |
| 9293 | |
| 9294 | Normally, when @value{GDBN} prints a code address, it includes the name |
| 9295 | of the function the address falls in: |
| 9296 | |
| 9297 | @smallexample |
| 9298 | (@value{GDBP}) print main |
| 9299 | $3 = @{int ()@} 0x11a0 <main> |
| 9300 | @end smallexample |
| 9301 | @noindent |
| 9302 | When overlay debugging is enabled, @value{GDBN} recognizes code in |
| 9303 | unmapped overlays, and prints the names of unmapped functions with |
| 9304 | asterisks around them. For example, if @code{foo} is a function in an |
| 9305 | unmapped overlay, @value{GDBN} prints it this way: |
| 9306 | |
| 9307 | @smallexample |
| 9308 | (@value{GDBP}) overlay list |
| 9309 | No sections are mapped. |
| 9310 | (@value{GDBP}) print foo |
| 9311 | $5 = @{int (int)@} 0x100000 <*foo*> |
| 9312 | @end smallexample |
| 9313 | @noindent |
| 9314 | When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's |
| 9315 | name normally: |
| 9316 | |
| 9317 | @smallexample |
| 9318 | (@value{GDBP}) overlay list |
| 9319 | Section .ov.foo.text, loaded at 0x100000 - 0x100034, |
| 9320 | mapped at 0x1016 - 0x104a |
| 9321 | (@value{GDBP}) print foo |
| 9322 | $6 = @{int (int)@} 0x1016 <foo> |
| 9323 | @end smallexample |
| 9324 | |
| 9325 | When overlay debugging is enabled, @value{GDBN} can find the correct |
| 9326 | address for functions and variables in an overlay, whether or not the |
| 9327 | overlay is mapped. This allows most @value{GDBN} commands, like |
| 9328 | @code{break} and @code{disassemble}, to work normally, even on unmapped |
| 9329 | code. However, @value{GDBN}'s breakpoint support has some limitations: |
| 9330 | |
| 9331 | @itemize @bullet |
| 9332 | @item |
| 9333 | @cindex breakpoints in overlays |
| 9334 | @cindex overlays, setting breakpoints in |
| 9335 | You can set breakpoints in functions in unmapped overlays, as long as |
| 9336 | @value{GDBN} can write to the overlay at its load address. |
| 9337 | @item |
| 9338 | @value{GDBN} can not set hardware or simulator-based breakpoints in |
| 9339 | unmapped overlays. However, if you set a breakpoint at the end of your |
| 9340 | overlay manager (and tell @value{GDBN} which overlays are now mapped, if |
| 9341 | you are using manual overlay management), @value{GDBN} will re-set its |
| 9342 | breakpoints properly. |
| 9343 | @end itemize |
| 9344 | |
| 9345 | |
| 9346 | @node Automatic Overlay Debugging |
| 9347 | @section Automatic Overlay Debugging |
| 9348 | @cindex automatic overlay debugging |
| 9349 | |
| 9350 | @value{GDBN} can automatically track which overlays are mapped and which |
| 9351 | are not, given some simple co-operation from the overlay manager in the |
| 9352 | inferior. If you enable automatic overlay debugging with the |
| 9353 | @code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN} |
| 9354 | looks in the inferior's memory for certain variables describing the |
| 9355 | current state of the overlays. |
| 9356 | |
| 9357 | Here are the variables your overlay manager must define to support |
| 9358 | @value{GDBN}'s automatic overlay debugging: |
| 9359 | |
| 9360 | @table @asis |
| 9361 | |
| 9362 | @item @code{_ovly_table}: |
| 9363 | This variable must be an array of the following structures: |
| 9364 | |
| 9365 | @smallexample |
| 9366 | struct |
| 9367 | @{ |
| 9368 | /* The overlay's mapped address. */ |
| 9369 | unsigned long vma; |
| 9370 | |
| 9371 | /* The size of the overlay, in bytes. */ |
| 9372 | unsigned long size; |
| 9373 | |
| 9374 | /* The overlay's load address. */ |
| 9375 | unsigned long lma; |
| 9376 | |
| 9377 | /* Non-zero if the overlay is currently mapped; |
| 9378 | zero otherwise. */ |
| 9379 | unsigned long mapped; |
| 9380 | @} |
| 9381 | @end smallexample |
| 9382 | |
| 9383 | @item @code{_novlys}: |
| 9384 | This variable must be a four-byte signed integer, holding the total |
| 9385 | number of elements in @code{_ovly_table}. |
| 9386 | |
| 9387 | @end table |
| 9388 | |
| 9389 | To decide whether a particular overlay is mapped or not, @value{GDBN} |
| 9390 | looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and |
| 9391 | @code{lma} members equal the VMA and LMA of the overlay's section in the |
| 9392 | executable file. When @value{GDBN} finds a matching entry, it consults |
| 9393 | the entry's @code{mapped} member to determine whether the overlay is |
| 9394 | currently mapped. |
| 9395 | |
| 9396 | In addition, your overlay manager may define a function called |
| 9397 | @code{_ovly_debug_event}. If this function is defined, @value{GDBN} |
| 9398 | will silently set a breakpoint there. If the overlay manager then |
| 9399 | calls this function whenever it has changed the overlay table, this |
| 9400 | will enable @value{GDBN} to accurately keep track of which overlays |
| 9401 | are in program memory, and update any breakpoints that may be set |
| 9402 | in overlays. This will allow breakpoints to work even if the |
| 9403 | overlays are kept in ROM or other non-writable memory while they |
| 9404 | are not being executed. |
| 9405 | |
| 9406 | @node Overlay Sample Program |
| 9407 | @section Overlay Sample Program |
| 9408 | @cindex overlay example program |
| 9409 | |
| 9410 | When linking a program which uses overlays, you must place the overlays |
| 9411 | at their load addresses, while relocating them to run at their mapped |
| 9412 | addresses. To do this, you must write a linker script (@pxref{Overlay |
| 9413 | Description,,, ld.info, Using ld: the GNU linker}). Unfortunately, |
| 9414 | since linker scripts are specific to a particular host system, target |
| 9415 | architecture, and target memory layout, this manual cannot provide |
| 9416 | portable sample code demonstrating @value{GDBN}'s overlay support. |
| 9417 | |
| 9418 | However, the @value{GDBN} source distribution does contain an overlaid |
| 9419 | program, with linker scripts for a few systems, as part of its test |
| 9420 | suite. The program consists of the following files from |
| 9421 | @file{gdb/testsuite/gdb.base}: |
| 9422 | |
| 9423 | @table @file |
| 9424 | @item overlays.c |
| 9425 | The main program file. |
| 9426 | @item ovlymgr.c |
| 9427 | A simple overlay manager, used by @file{overlays.c}. |
| 9428 | @item foo.c |
| 9429 | @itemx bar.c |
| 9430 | @itemx baz.c |
| 9431 | @itemx grbx.c |
| 9432 | Overlay modules, loaded and used by @file{overlays.c}. |
| 9433 | @item d10v.ld |
| 9434 | @itemx m32r.ld |
| 9435 | Linker scripts for linking the test program on the @code{d10v-elf} |
| 9436 | and @code{m32r-elf} targets. |
| 9437 | @end table |
| 9438 | |
| 9439 | You can build the test program using the @code{d10v-elf} GCC |
| 9440 | cross-compiler like this: |
| 9441 | |
| 9442 | @smallexample |
| 9443 | $ d10v-elf-gcc -g -c overlays.c |
| 9444 | $ d10v-elf-gcc -g -c ovlymgr.c |
| 9445 | $ d10v-elf-gcc -g -c foo.c |
| 9446 | $ d10v-elf-gcc -g -c bar.c |
| 9447 | $ d10v-elf-gcc -g -c baz.c |
| 9448 | $ d10v-elf-gcc -g -c grbx.c |
| 9449 | $ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \ |
| 9450 | baz.o grbx.o -Wl,-Td10v.ld -o overlays |
| 9451 | @end smallexample |
| 9452 | |
| 9453 | The build process is identical for any other architecture, except that |
| 9454 | you must substitute the appropriate compiler and linker script for the |
| 9455 | target system for @code{d10v-elf-gcc} and @code{d10v.ld}. |
| 9456 | |
| 9457 | |
| 9458 | @node Languages |
| 9459 | @chapter Using @value{GDBN} with Different Languages |
| 9460 | @cindex languages |
| 9461 | |
| 9462 | Although programming languages generally have common aspects, they are |
| 9463 | rarely expressed in the same manner. For instance, in ANSI C, |
| 9464 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in |
| 9465 | Modula-2, it is accomplished by @code{p^}. Values can also be |
| 9466 | represented (and displayed) differently. Hex numbers in C appear as |
| 9467 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. |
| 9468 | |
| 9469 | @cindex working language |
| 9470 | Language-specific information is built into @value{GDBN} for some languages, |
| 9471 | allowing you to express operations like the above in your program's |
| 9472 | native language, and allowing @value{GDBN} to output values in a manner |
| 9473 | consistent with the syntax of your program's native language. The |
| 9474 | language you use to build expressions is called the @dfn{working |
| 9475 | language}. |
| 9476 | |
| 9477 | @menu |
| 9478 | * Setting:: Switching between source languages |
| 9479 | * Show:: Displaying the language |
| 9480 | * Checks:: Type and range checks |
| 9481 | * Supported Languages:: Supported languages |
| 9482 | * Unsupported Languages:: Unsupported languages |
| 9483 | @end menu |
| 9484 | |
| 9485 | @node Setting |
| 9486 | @section Switching Between Source Languages |
| 9487 | |
| 9488 | There are two ways to control the working language---either have @value{GDBN} |
| 9489 | set it automatically, or select it manually yourself. You can use the |
| 9490 | @code{set language} command for either purpose. On startup, @value{GDBN} |
| 9491 | defaults to setting the language automatically. The working language is |
| 9492 | used to determine how expressions you type are interpreted, how values |
| 9493 | are printed, etc. |
| 9494 | |
| 9495 | In addition to the working language, every source file that |
| 9496 | @value{GDBN} knows about has its own working language. For some object |
| 9497 | file formats, the compiler might indicate which language a particular |
| 9498 | source file is in. However, most of the time @value{GDBN} infers the |
| 9499 | language from the name of the file. The language of a source file |
| 9500 | controls whether C@t{++} names are demangled---this way @code{backtrace} can |
| 9501 | show each frame appropriately for its own language. There is no way to |
| 9502 | set the language of a source file from within @value{GDBN}, but you can |
| 9503 | set the language associated with a filename extension. @xref{Show, , |
| 9504 | Displaying the Language}. |
| 9505 | |
| 9506 | This is most commonly a problem when you use a program, such |
| 9507 | as @code{cfront} or @code{f2c}, that generates C but is written in |
| 9508 | another language. In that case, make the |
| 9509 | program use @code{#line} directives in its C output; that way |
| 9510 | @value{GDBN} will know the correct language of the source code of the original |
| 9511 | program, and will display that source code, not the generated C code. |
| 9512 | |
| 9513 | @menu |
| 9514 | * Filenames:: Filename extensions and languages. |
| 9515 | * Manually:: Setting the working language manually |
| 9516 | * Automatically:: Having @value{GDBN} infer the source language |
| 9517 | @end menu |
| 9518 | |
| 9519 | @node Filenames |
| 9520 | @subsection List of Filename Extensions and Languages |
| 9521 | |
| 9522 | If a source file name ends in one of the following extensions, then |
| 9523 | @value{GDBN} infers that its language is the one indicated. |
| 9524 | |
| 9525 | @table @file |
| 9526 | @item .ada |
| 9527 | @itemx .ads |
| 9528 | @itemx .adb |
| 9529 | @itemx .a |
| 9530 | Ada source file. |
| 9531 | |
| 9532 | @item .c |
| 9533 | C source file |
| 9534 | |
| 9535 | @item .C |
| 9536 | @itemx .cc |
| 9537 | @itemx .cp |
| 9538 | @itemx .cpp |
| 9539 | @itemx .cxx |
| 9540 | @itemx .c++ |
| 9541 | C@t{++} source file |
| 9542 | |
| 9543 | @item .m |
| 9544 | Objective-C source file |
| 9545 | |
| 9546 | @item .f |
| 9547 | @itemx .F |
| 9548 | Fortran source file |
| 9549 | |
| 9550 | @item .mod |
| 9551 | Modula-2 source file |
| 9552 | |
| 9553 | @item .s |
| 9554 | @itemx .S |
| 9555 | Assembler source file. This actually behaves almost like C, but |
| 9556 | @value{GDBN} does not skip over function prologues when stepping. |
| 9557 | @end table |
| 9558 | |
| 9559 | In addition, you may set the language associated with a filename |
| 9560 | extension. @xref{Show, , Displaying the Language}. |
| 9561 | |
| 9562 | @node Manually |
| 9563 | @subsection Setting the Working Language |
| 9564 | |
| 9565 | If you allow @value{GDBN} to set the language automatically, |
| 9566 | expressions are interpreted the same way in your debugging session and |
| 9567 | your program. |
| 9568 | |
| 9569 | @kindex set language |
| 9570 | If you wish, you may set the language manually. To do this, issue the |
| 9571 | command @samp{set language @var{lang}}, where @var{lang} is the name of |
| 9572 | a language, such as |
| 9573 | @code{c} or @code{modula-2}. |
| 9574 | For a list of the supported languages, type @samp{set language}. |
| 9575 | |
| 9576 | Setting the language manually prevents @value{GDBN} from updating the working |
| 9577 | language automatically. This can lead to confusion if you try |
| 9578 | to debug a program when the working language is not the same as the |
| 9579 | source language, when an expression is acceptable to both |
| 9580 | languages---but means different things. For instance, if the current |
| 9581 | source file were written in C, and @value{GDBN} was parsing Modula-2, a |
| 9582 | command such as: |
| 9583 | |
| 9584 | @smallexample |
| 9585 | print a = b + c |
| 9586 | @end smallexample |
| 9587 | |
| 9588 | @noindent |
| 9589 | might not have the effect you intended. In C, this means to add |
| 9590 | @code{b} and @code{c} and place the result in @code{a}. The result |
| 9591 | printed would be the value of @code{a}. In Modula-2, this means to compare |
| 9592 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. |
| 9593 | |
| 9594 | @node Automatically |
| 9595 | @subsection Having @value{GDBN} Infer the Source Language |
| 9596 | |
| 9597 | To have @value{GDBN} set the working language automatically, use |
| 9598 | @samp{set language local} or @samp{set language auto}. @value{GDBN} |
| 9599 | then infers the working language. That is, when your program stops in a |
| 9600 | frame (usually by encountering a breakpoint), @value{GDBN} sets the |
| 9601 | working language to the language recorded for the function in that |
| 9602 | frame. If the language for a frame is unknown (that is, if the function |
| 9603 | or block corresponding to the frame was defined in a source file that |
| 9604 | does not have a recognized extension), the current working language is |
| 9605 | not changed, and @value{GDBN} issues a warning. |
| 9606 | |
| 9607 | This may not seem necessary for most programs, which are written |
| 9608 | entirely in one source language. However, program modules and libraries |
| 9609 | written in one source language can be used by a main program written in |
| 9610 | a different source language. Using @samp{set language auto} in this |
| 9611 | case frees you from having to set the working language manually. |
| 9612 | |
| 9613 | @node Show |
| 9614 | @section Displaying the Language |
| 9615 | |
| 9616 | The following commands help you find out which language is the |
| 9617 | working language, and also what language source files were written in. |
| 9618 | |
| 9619 | @table @code |
| 9620 | @item show language |
| 9621 | @kindex show language |
| 9622 | Display the current working language. This is the |
| 9623 | language you can use with commands such as @code{print} to |
| 9624 | build and compute expressions that may involve variables in your program. |
| 9625 | |
| 9626 | @item info frame |
| 9627 | @kindex info frame@r{, show the source language} |
| 9628 | Display the source language for this frame. This language becomes the |
| 9629 | working language if you use an identifier from this frame. |
| 9630 | @xref{Frame Info, ,Information about a Frame}, to identify the other |
| 9631 | information listed here. |
| 9632 | |
| 9633 | @item info source |
| 9634 | @kindex info source@r{, show the source language} |
| 9635 | Display the source language of this source file. |
| 9636 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other |
| 9637 | information listed here. |
| 9638 | @end table |
| 9639 | |
| 9640 | In unusual circumstances, you may have source files with extensions |
| 9641 | not in the standard list. You can then set the extension associated |
| 9642 | with a language explicitly: |
| 9643 | |
| 9644 | @table @code |
| 9645 | @item set extension-language @var{ext} @var{language} |
| 9646 | @kindex set extension-language |
| 9647 | Tell @value{GDBN} that source files with extension @var{ext} are to be |
| 9648 | assumed as written in the source language @var{language}. |
| 9649 | |
| 9650 | @item info extensions |
| 9651 | @kindex info extensions |
| 9652 | List all the filename extensions and the associated languages. |
| 9653 | @end table |
| 9654 | |
| 9655 | @node Checks |
| 9656 | @section Type and Range Checking |
| 9657 | |
| 9658 | @quotation |
| 9659 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range |
| 9660 | checking are included, but they do not yet have any effect. This |
| 9661 | section documents the intended facilities. |
| 9662 | @end quotation |
| 9663 | @c FIXME remove warning when type/range code added |
| 9664 | |
| 9665 | Some languages are designed to guard you against making seemingly common |
| 9666 | errors through a series of compile- and run-time checks. These include |
| 9667 | checking the type of arguments to functions and operators, and making |
| 9668 | sure mathematical overflows are caught at run time. Checks such as |
| 9669 | these help to ensure a program's correctness once it has been compiled |
| 9670 | by eliminating type mismatches, and providing active checks for range |
| 9671 | errors when your program is running. |
| 9672 | |
| 9673 | @value{GDBN} can check for conditions like the above if you wish. |
| 9674 | Although @value{GDBN} does not check the statements in your program, |
| 9675 | it can check expressions entered directly into @value{GDBN} for |
| 9676 | evaluation via the @code{print} command, for example. As with the |
| 9677 | working language, @value{GDBN} can also decide whether or not to check |
| 9678 | automatically based on your program's source language. |
| 9679 | @xref{Supported Languages, ,Supported Languages}, for the default |
| 9680 | settings of supported languages. |
| 9681 | |
| 9682 | @menu |
| 9683 | * Type Checking:: An overview of type checking |
| 9684 | * Range Checking:: An overview of range checking |
| 9685 | @end menu |
| 9686 | |
| 9687 | @cindex type checking |
| 9688 | @cindex checks, type |
| 9689 | @node Type Checking |
| 9690 | @subsection An Overview of Type Checking |
| 9691 | |
| 9692 | Some languages, such as Modula-2, are strongly typed, meaning that the |
| 9693 | arguments to operators and functions have to be of the correct type, |
| 9694 | otherwise an error occurs. These checks prevent type mismatch |
| 9695 | errors from ever causing any run-time problems. For example, |
| 9696 | |
| 9697 | @smallexample |
| 9698 | 1 + 2 @result{} 3 |
| 9699 | @exdent but |
| 9700 | @error{} 1 + 2.3 |
| 9701 | @end smallexample |
| 9702 | |
| 9703 | The second example fails because the @code{CARDINAL} 1 is not |
| 9704 | type-compatible with the @code{REAL} 2.3. |
| 9705 | |
| 9706 | For the expressions you use in @value{GDBN} commands, you can tell the |
| 9707 | @value{GDBN} type checker to skip checking; |
| 9708 | to treat any mismatches as errors and abandon the expression; |
| 9709 | or to only issue warnings when type mismatches occur, |
| 9710 | but evaluate the expression anyway. When you choose the last of |
| 9711 | these, @value{GDBN} evaluates expressions like the second example above, but |
| 9712 | also issues a warning. |
| 9713 | |
| 9714 | Even if you turn type checking off, there may be other reasons |
| 9715 | related to type that prevent @value{GDBN} from evaluating an expression. |
| 9716 | For instance, @value{GDBN} does not know how to add an @code{int} and |
| 9717 | a @code{struct foo}. These particular type errors have nothing to do |
| 9718 | with the language in use, and usually arise from expressions, such as |
| 9719 | the one described above, which make little sense to evaluate anyway. |
| 9720 | |
| 9721 | Each language defines to what degree it is strict about type. For |
| 9722 | instance, both Modula-2 and C require the arguments to arithmetical |
| 9723 | operators to be numbers. In C, enumerated types and pointers can be |
| 9724 | represented as numbers, so that they are valid arguments to mathematical |
| 9725 | operators. @xref{Supported Languages, ,Supported Languages}, for further |
| 9726 | details on specific languages. |
| 9727 | |
| 9728 | @value{GDBN} provides some additional commands for controlling the type checker: |
| 9729 | |
| 9730 | @kindex set check type |
| 9731 | @kindex show check type |
| 9732 | @table @code |
| 9733 | @item set check type auto |
| 9734 | Set type checking on or off based on the current working language. |
| 9735 | @xref{Supported Languages, ,Supported Languages}, for the default settings for |
| 9736 | each language. |
| 9737 | |
| 9738 | @item set check type on |
| 9739 | @itemx set check type off |
| 9740 | Set type checking on or off, overriding the default setting for the |
| 9741 | current working language. Issue a warning if the setting does not |
| 9742 | match the language default. If any type mismatches occur in |
| 9743 | evaluating an expression while type checking is on, @value{GDBN} prints a |
| 9744 | message and aborts evaluation of the expression. |
| 9745 | |
| 9746 | @item set check type warn |
| 9747 | Cause the type checker to issue warnings, but to always attempt to |
| 9748 | evaluate the expression. Evaluating the expression may still |
| 9749 | be impossible for other reasons. For example, @value{GDBN} cannot add |
| 9750 | numbers and structures. |
| 9751 | |
| 9752 | @item show type |
| 9753 | Show the current setting of the type checker, and whether or not @value{GDBN} |
| 9754 | is setting it automatically. |
| 9755 | @end table |
| 9756 | |
| 9757 | @cindex range checking |
| 9758 | @cindex checks, range |
| 9759 | @node Range Checking |
| 9760 | @subsection An Overview of Range Checking |
| 9761 | |
| 9762 | In some languages (such as Modula-2), it is an error to exceed the |
| 9763 | bounds of a type; this is enforced with run-time checks. Such range |
| 9764 | checking is meant to ensure program correctness by making sure |
| 9765 | computations do not overflow, or indices on an array element access do |
| 9766 | not exceed the bounds of the array. |
| 9767 | |
| 9768 | For expressions you use in @value{GDBN} commands, you can tell |
| 9769 | @value{GDBN} to treat range errors in one of three ways: ignore them, |
| 9770 | always treat them as errors and abandon the expression, or issue |
| 9771 | warnings but evaluate the expression anyway. |
| 9772 | |
| 9773 | A range error can result from numerical overflow, from exceeding an |
| 9774 | array index bound, or when you type a constant that is not a member |
| 9775 | of any type. Some languages, however, do not treat overflows as an |
| 9776 | error. In many implementations of C, mathematical overflow causes the |
| 9777 | result to ``wrap around'' to lower values---for example, if @var{m} is |
| 9778 | the largest integer value, and @var{s} is the smallest, then |
| 9779 | |
| 9780 | @smallexample |
| 9781 | @var{m} + 1 @result{} @var{s} |
| 9782 | @end smallexample |
| 9783 | |
| 9784 | This, too, is specific to individual languages, and in some cases |
| 9785 | specific to individual compilers or machines. @xref{Supported Languages, , |
| 9786 | Supported Languages}, for further details on specific languages. |
| 9787 | |
| 9788 | @value{GDBN} provides some additional commands for controlling the range checker: |
| 9789 | |
| 9790 | @kindex set check range |
| 9791 | @kindex show check range |
| 9792 | @table @code |
| 9793 | @item set check range auto |
| 9794 | Set range checking on or off based on the current working language. |
| 9795 | @xref{Supported Languages, ,Supported Languages}, for the default settings for |
| 9796 | each language. |
| 9797 | |
| 9798 | @item set check range on |
| 9799 | @itemx set check range off |
| 9800 | Set range checking on or off, overriding the default setting for the |
| 9801 | current working language. A warning is issued if the setting does not |
| 9802 | match the language default. If a range error occurs and range checking is on, |
| 9803 | then a message is printed and evaluation of the expression is aborted. |
| 9804 | |
| 9805 | @item set check range warn |
| 9806 | Output messages when the @value{GDBN} range checker detects a range error, |
| 9807 | but attempt to evaluate the expression anyway. Evaluating the |
| 9808 | expression may still be impossible for other reasons, such as accessing |
| 9809 | memory that the process does not own (a typical example from many Unix |
| 9810 | systems). |
| 9811 | |
| 9812 | @item show range |
| 9813 | Show the current setting of the range checker, and whether or not it is |
| 9814 | being set automatically by @value{GDBN}. |
| 9815 | @end table |
| 9816 | |
| 9817 | @node Supported Languages |
| 9818 | @section Supported Languages |
| 9819 | |
| 9820 | @value{GDBN} supports C, C@t{++}, Objective-C, Fortran, Java, Pascal, |
| 9821 | assembly, Modula-2, and Ada. |
| 9822 | @c This is false ... |
| 9823 | Some @value{GDBN} features may be used in expressions regardless of the |
| 9824 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, |
| 9825 | and the @samp{@{type@}addr} construct (@pxref{Expressions, |
| 9826 | ,Expressions}) can be used with the constructs of any supported |
| 9827 | language. |
| 9828 | |
| 9829 | The following sections detail to what degree each source language is |
| 9830 | supported by @value{GDBN}. These sections are not meant to be language |
| 9831 | tutorials or references, but serve only as a reference guide to what the |
| 9832 | @value{GDBN} expression parser accepts, and what input and output |
| 9833 | formats should look like for different languages. There are many good |
| 9834 | books written on each of these languages; please look to these for a |
| 9835 | language reference or tutorial. |
| 9836 | |
| 9837 | @menu |
| 9838 | * C:: C and C@t{++} |
| 9839 | * Objective-C:: Objective-C |
| 9840 | * Fortran:: Fortran |
| 9841 | * Pascal:: Pascal |
| 9842 | * Modula-2:: Modula-2 |
| 9843 | * Ada:: Ada |
| 9844 | @end menu |
| 9845 | |
| 9846 | @node C |
| 9847 | @subsection C and C@t{++} |
| 9848 | |
| 9849 | @cindex C and C@t{++} |
| 9850 | @cindex expressions in C or C@t{++} |
| 9851 | |
| 9852 | Since C and C@t{++} are so closely related, many features of @value{GDBN} apply |
| 9853 | to both languages. Whenever this is the case, we discuss those languages |
| 9854 | together. |
| 9855 | |
| 9856 | @cindex C@t{++} |
| 9857 | @cindex @code{g++}, @sc{gnu} C@t{++} compiler |
| 9858 | @cindex @sc{gnu} C@t{++} |
| 9859 | The C@t{++} debugging facilities are jointly implemented by the C@t{++} |
| 9860 | compiler and @value{GDBN}. Therefore, to debug your C@t{++} code |
| 9861 | effectively, you must compile your C@t{++} programs with a supported |
| 9862 | C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++} |
| 9863 | compiler (@code{aCC}). |
| 9864 | |
| 9865 | For best results when using @sc{gnu} C@t{++}, use the DWARF 2 debugging |
| 9866 | format; if it doesn't work on your system, try the stabs+ debugging |
| 9867 | format. You can select those formats explicitly with the @code{g++} |
| 9868 | command-line options @option{-gdwarf-2} and @option{-gstabs+}. |
| 9869 | @xref{Debugging Options,,Options for Debugging Your Program or GCC, |
| 9870 | gcc.info, Using the @sc{gnu} Compiler Collection (GCC)}. |
| 9871 | |
| 9872 | @menu |
| 9873 | * C Operators:: C and C@t{++} operators |
| 9874 | * C Constants:: C and C@t{++} constants |
| 9875 | * C Plus Plus Expressions:: C@t{++} expressions |
| 9876 | * C Defaults:: Default settings for C and C@t{++} |
| 9877 | * C Checks:: C and C@t{++} type and range checks |
| 9878 | * Debugging C:: @value{GDBN} and C |
| 9879 | * Debugging C Plus Plus:: @value{GDBN} features for C@t{++} |
| 9880 | * Decimal Floating Point:: Numbers in Decimal Floating Point format |
| 9881 | @end menu |
| 9882 | |
| 9883 | @node C Operators |
| 9884 | @subsubsection C and C@t{++} Operators |
| 9885 | |
| 9886 | @cindex C and C@t{++} operators |
| 9887 | |
| 9888 | Operators must be defined on values of specific types. For instance, |
| 9889 | @code{+} is defined on numbers, but not on structures. Operators are |
| 9890 | often defined on groups of types. |
| 9891 | |
| 9892 | For the purposes of C and C@t{++}, the following definitions hold: |
| 9893 | |
| 9894 | @itemize @bullet |
| 9895 | |
| 9896 | @item |
| 9897 | @emph{Integral types} include @code{int} with any of its storage-class |
| 9898 | specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}. |
| 9899 | |
| 9900 | @item |
| 9901 | @emph{Floating-point types} include @code{float}, @code{double}, and |
| 9902 | @code{long double} (if supported by the target platform). |
| 9903 | |
| 9904 | @item |
| 9905 | @emph{Pointer types} include all types defined as @code{(@var{type} *)}. |
| 9906 | |
| 9907 | @item |
| 9908 | @emph{Scalar types} include all of the above. |
| 9909 | |
| 9910 | @end itemize |
| 9911 | |
| 9912 | @noindent |
| 9913 | The following operators are supported. They are listed here |
| 9914 | in order of increasing precedence: |
| 9915 | |
| 9916 | @table @code |
| 9917 | @item , |
| 9918 | The comma or sequencing operator. Expressions in a comma-separated list |
| 9919 | are evaluated from left to right, with the result of the entire |
| 9920 | expression being the last expression evaluated. |
| 9921 | |
| 9922 | @item = |
| 9923 | Assignment. The value of an assignment expression is the value |
| 9924 | assigned. Defined on scalar types. |
| 9925 | |
| 9926 | @item @var{op}= |
| 9927 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, |
| 9928 | and translated to @w{@code{@var{a} = @var{a op b}}}. |
| 9929 | @w{@code{@var{op}=}} and @code{=} have the same precedence. |
| 9930 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, |
| 9931 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. |
| 9932 | |
| 9933 | @item ?: |
| 9934 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought |
| 9935 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an |
| 9936 | integral type. |
| 9937 | |
| 9938 | @item || |
| 9939 | Logical @sc{or}. Defined on integral types. |
| 9940 | |
| 9941 | @item && |
| 9942 | Logical @sc{and}. Defined on integral types. |
| 9943 | |
| 9944 | @item | |
| 9945 | Bitwise @sc{or}. Defined on integral types. |
| 9946 | |
| 9947 | @item ^ |
| 9948 | Bitwise exclusive-@sc{or}. Defined on integral types. |
| 9949 | |
| 9950 | @item & |
| 9951 | Bitwise @sc{and}. Defined on integral types. |
| 9952 | |
| 9953 | @item ==@r{, }!= |
| 9954 | Equality and inequality. Defined on scalar types. The value of these |
| 9955 | expressions is 0 for false and non-zero for true. |
| 9956 | |
| 9957 | @item <@r{, }>@r{, }<=@r{, }>= |
| 9958 | Less than, greater than, less than or equal, greater than or equal. |
| 9959 | Defined on scalar types. The value of these expressions is 0 for false |
| 9960 | and non-zero for true. |
| 9961 | |
| 9962 | @item <<@r{, }>> |
| 9963 | left shift, and right shift. Defined on integral types. |
| 9964 | |
| 9965 | @item @@ |
| 9966 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
| 9967 | |
| 9968 | @item +@r{, }- |
| 9969 | Addition and subtraction. Defined on integral types, floating-point types and |
| 9970 | pointer types. |
| 9971 | |
| 9972 | @item *@r{, }/@r{, }% |
| 9973 | Multiplication, division, and modulus. Multiplication and division are |
| 9974 | defined on integral and floating-point types. Modulus is defined on |
| 9975 | integral types. |
| 9976 | |
| 9977 | @item ++@r{, }-- |
| 9978 | Increment and decrement. When appearing before a variable, the |
| 9979 | operation is performed before the variable is used in an expression; |
| 9980 | when appearing after it, the variable's value is used before the |
| 9981 | operation takes place. |
| 9982 | |
| 9983 | @item * |
| 9984 | Pointer dereferencing. Defined on pointer types. Same precedence as |
| 9985 | @code{++}. |
| 9986 | |
| 9987 | @item & |
| 9988 | Address operator. Defined on variables. Same precedence as @code{++}. |
| 9989 | |
| 9990 | For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is |
| 9991 | allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})} |
| 9992 | to examine the address |
| 9993 | where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is |
| 9994 | stored. |
| 9995 | |
| 9996 | @item - |
| 9997 | Negative. Defined on integral and floating-point types. Same |
| 9998 | precedence as @code{++}. |
| 9999 | |
| 10000 | @item ! |
| 10001 | Logical negation. Defined on integral types. Same precedence as |
| 10002 | @code{++}. |
| 10003 | |
| 10004 | @item ~ |
| 10005 | Bitwise complement operator. Defined on integral types. Same precedence as |
| 10006 | @code{++}. |
| 10007 | |
| 10008 | |
| 10009 | @item .@r{, }-> |
| 10010 | Structure member, and pointer-to-structure member. For convenience, |
| 10011 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a |
| 10012 | pointer based on the stored type information. |
| 10013 | Defined on @code{struct} and @code{union} data. |
| 10014 | |
| 10015 | @item .*@r{, }->* |
| 10016 | Dereferences of pointers to members. |
| 10017 | |
| 10018 | @item [] |
| 10019 | Array indexing. @code{@var{a}[@var{i}]} is defined as |
| 10020 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. |
| 10021 | |
| 10022 | @item () |
| 10023 | Function parameter list. Same precedence as @code{->}. |
| 10024 | |
| 10025 | @item :: |
| 10026 | C@t{++} scope resolution operator. Defined on @code{struct}, @code{union}, |
| 10027 | and @code{class} types. |
| 10028 | |
| 10029 | @item :: |
| 10030 | Doubled colons also represent the @value{GDBN} scope operator |
| 10031 | (@pxref{Expressions, ,Expressions}). Same precedence as @code{::}, |
| 10032 | above. |
| 10033 | @end table |
| 10034 | |
| 10035 | If an operator is redefined in the user code, @value{GDBN} usually |
| 10036 | attempts to invoke the redefined version instead of using the operator's |
| 10037 | predefined meaning. |
| 10038 | |
| 10039 | @node C Constants |
| 10040 | @subsubsection C and C@t{++} Constants |
| 10041 | |
| 10042 | @cindex C and C@t{++} constants |
| 10043 | |
| 10044 | @value{GDBN} allows you to express the constants of C and C@t{++} in the |
| 10045 | following ways: |
| 10046 | |
| 10047 | @itemize @bullet |
| 10048 | @item |
| 10049 | Integer constants are a sequence of digits. Octal constants are |
| 10050 | specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants |
| 10051 | by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter |
| 10052 | @samp{l}, specifying that the constant should be treated as a |
| 10053 | @code{long} value. |
| 10054 | |
| 10055 | @item |
| 10056 | Floating point constants are a sequence of digits, followed by a decimal |
| 10057 | point, followed by a sequence of digits, and optionally followed by an |
| 10058 | exponent. An exponent is of the form: |
| 10059 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another |
| 10060 | sequence of digits. The @samp{+} is optional for positive exponents. |
| 10061 | A floating-point constant may also end with a letter @samp{f} or |
| 10062 | @samp{F}, specifying that the constant should be treated as being of |
| 10063 | the @code{float} (as opposed to the default @code{double}) type; or with |
| 10064 | a letter @samp{l} or @samp{L}, which specifies a @code{long double} |
| 10065 | constant. |
| 10066 | |
| 10067 | @item |
| 10068 | Enumerated constants consist of enumerated identifiers, or their |
| 10069 | integral equivalents. |
| 10070 | |
| 10071 | @item |
| 10072 | Character constants are a single character surrounded by single quotes |
| 10073 | (@code{'}), or a number---the ordinal value of the corresponding character |
| 10074 | (usually its @sc{ascii} value). Within quotes, the single character may |
| 10075 | be represented by a letter or by @dfn{escape sequences}, which are of |
| 10076 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation |
| 10077 | of the character's ordinal value; or of the form @samp{\@var{x}}, where |
| 10078 | @samp{@var{x}} is a predefined special character---for example, |
| 10079 | @samp{\n} for newline. |
| 10080 | |
| 10081 | @item |
| 10082 | String constants are a sequence of character constants surrounded by |
| 10083 | double quotes (@code{"}). Any valid character constant (as described |
| 10084 | above) may appear. Double quotes within the string must be preceded by |
| 10085 | a backslash, so for instance @samp{"a\"b'c"} is a string of five |
| 10086 | characters. |
| 10087 | |
| 10088 | @item |
| 10089 | Pointer constants are an integral value. You can also write pointers |
| 10090 | to constants using the C operator @samp{&}. |
| 10091 | |
| 10092 | @item |
| 10093 | Array constants are comma-separated lists surrounded by braces @samp{@{} |
| 10094 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of |
| 10095 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, |
| 10096 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. |
| 10097 | @end itemize |
| 10098 | |
| 10099 | @node C Plus Plus Expressions |
| 10100 | @subsubsection C@t{++} Expressions |
| 10101 | |
| 10102 | @cindex expressions in C@t{++} |
| 10103 | @value{GDBN} expression handling can interpret most C@t{++} expressions. |
| 10104 | |
| 10105 | @cindex debugging C@t{++} programs |
| 10106 | @cindex C@t{++} compilers |
| 10107 | @cindex debug formats and C@t{++} |
| 10108 | @cindex @value{NGCC} and C@t{++} |
| 10109 | @quotation |
| 10110 | @emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use the |
| 10111 | proper compiler and the proper debug format. Currently, @value{GDBN} |
| 10112 | works best when debugging C@t{++} code that is compiled with |
| 10113 | @value{NGCC} 2.95.3 or with @value{NGCC} 3.1 or newer, using the options |
| 10114 | @option{-gdwarf-2} or @option{-gstabs+}. DWARF 2 is preferred over |
| 10115 | stabs+. Most configurations of @value{NGCC} emit either DWARF 2 or |
| 10116 | stabs+ as their default debug format, so you usually don't need to |
| 10117 | specify a debug format explicitly. Other compilers and/or debug formats |
| 10118 | are likely to work badly or not at all when using @value{GDBN} to debug |
| 10119 | C@t{++} code. |
| 10120 | @end quotation |
| 10121 | |
| 10122 | @enumerate |
| 10123 | |
| 10124 | @cindex member functions |
| 10125 | @item |
| 10126 | Member function calls are allowed; you can use expressions like |
| 10127 | |
| 10128 | @smallexample |
| 10129 | count = aml->GetOriginal(x, y) |
| 10130 | @end smallexample |
| 10131 | |
| 10132 | @vindex this@r{, inside C@t{++} member functions} |
| 10133 | @cindex namespace in C@t{++} |
| 10134 | @item |
| 10135 | While a member function is active (in the selected stack frame), your |
| 10136 | expressions have the same namespace available as the member function; |
| 10137 | that is, @value{GDBN} allows implicit references to the class instance |
| 10138 | pointer @code{this} following the same rules as C@t{++}. |
| 10139 | |
| 10140 | @cindex call overloaded functions |
| 10141 | @cindex overloaded functions, calling |
| 10142 | @cindex type conversions in C@t{++} |
| 10143 | @item |
| 10144 | You can call overloaded functions; @value{GDBN} resolves the function |
| 10145 | call to the right definition, with some restrictions. @value{GDBN} does not |
| 10146 | perform overload resolution involving user-defined type conversions, |
| 10147 | calls to constructors, or instantiations of templates that do not exist |
| 10148 | in the program. It also cannot handle ellipsis argument lists or |
| 10149 | default arguments. |
| 10150 | |
| 10151 | It does perform integral conversions and promotions, floating-point |
| 10152 | promotions, arithmetic conversions, pointer conversions, conversions of |
| 10153 | class objects to base classes, and standard conversions such as those of |
| 10154 | functions or arrays to pointers; it requires an exact match on the |
| 10155 | number of function arguments. |
| 10156 | |
| 10157 | Overload resolution is always performed, unless you have specified |
| 10158 | @code{set overload-resolution off}. @xref{Debugging C Plus Plus, |
| 10159 | ,@value{GDBN} Features for C@t{++}}. |
| 10160 | |
| 10161 | You must specify @code{set overload-resolution off} in order to use an |
| 10162 | explicit function signature to call an overloaded function, as in |
| 10163 | @smallexample |
| 10164 | p 'foo(char,int)'('x', 13) |
| 10165 | @end smallexample |
| 10166 | |
| 10167 | The @value{GDBN} command-completion facility can simplify this; |
| 10168 | see @ref{Completion, ,Command Completion}. |
| 10169 | |
| 10170 | @cindex reference declarations |
| 10171 | @item |
| 10172 | @value{GDBN} understands variables declared as C@t{++} references; you can use |
| 10173 | them in expressions just as you do in C@t{++} source---they are automatically |
| 10174 | dereferenced. |
| 10175 | |
| 10176 | In the parameter list shown when @value{GDBN} displays a frame, the values of |
| 10177 | reference variables are not displayed (unlike other variables); this |
| 10178 | avoids clutter, since references are often used for large structures. |
| 10179 | The @emph{address} of a reference variable is always shown, unless |
| 10180 | you have specified @samp{set print address off}. |
| 10181 | |
| 10182 | @item |
| 10183 | @value{GDBN} supports the C@t{++} name resolution operator @code{::}---your |
| 10184 | expressions can use it just as expressions in your program do. Since |
| 10185 | one scope may be defined in another, you can use @code{::} repeatedly if |
| 10186 | necessary, for example in an expression like |
| 10187 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows |
| 10188 | resolving name scope by reference to source files, in both C and C@t{++} |
| 10189 | debugging (@pxref{Variables, ,Program Variables}). |
| 10190 | @end enumerate |
| 10191 | |
| 10192 | In addition, when used with HP's C@t{++} compiler, @value{GDBN} supports |
| 10193 | calling virtual functions correctly, printing out virtual bases of |
| 10194 | objects, calling functions in a base subobject, casting objects, and |
| 10195 | invoking user-defined operators. |
| 10196 | |
| 10197 | @node C Defaults |
| 10198 | @subsubsection C and C@t{++} Defaults |
| 10199 | |
| 10200 | @cindex C and C@t{++} defaults |
| 10201 | |
| 10202 | If you allow @value{GDBN} to set type and range checking automatically, they |
| 10203 | both default to @code{off} whenever the working language changes to |
| 10204 | C or C@t{++}. This happens regardless of whether you or @value{GDBN} |
| 10205 | selects the working language. |
| 10206 | |
| 10207 | If you allow @value{GDBN} to set the language automatically, it |
| 10208 | recognizes source files whose names end with @file{.c}, @file{.C}, or |
| 10209 | @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of |
| 10210 | these files, it sets the working language to C or C@t{++}. |
| 10211 | @xref{Automatically, ,Having @value{GDBN} Infer the Source Language}, |
| 10212 | for further details. |
| 10213 | |
| 10214 | @c Type checking is (a) primarily motivated by Modula-2, and (b) |
| 10215 | @c unimplemented. If (b) changes, it might make sense to let this node |
| 10216 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. |
| 10217 | |
| 10218 | @node C Checks |
| 10219 | @subsubsection C and C@t{++} Type and Range Checks |
| 10220 | |
| 10221 | @cindex C and C@t{++} checks |
| 10222 | |
| 10223 | By default, when @value{GDBN} parses C or C@t{++} expressions, type checking |
| 10224 | is not used. However, if you turn type checking on, @value{GDBN} |
| 10225 | considers two variables type equivalent if: |
| 10226 | |
| 10227 | @itemize @bullet |
| 10228 | @item |
| 10229 | The two variables are structured and have the same structure, union, or |
| 10230 | enumerated tag. |
| 10231 | |
| 10232 | @item |
| 10233 | The two variables have the same type name, or types that have been |
| 10234 | declared equivalent through @code{typedef}. |
| 10235 | |
| 10236 | @ignore |
| 10237 | @c leaving this out because neither J Gilmore nor R Pesch understand it. |
| 10238 | @c FIXME--beers? |
| 10239 | @item |
| 10240 | The two @code{struct}, @code{union}, or @code{enum} variables are |
| 10241 | declared in the same declaration. (Note: this may not be true for all C |
| 10242 | compilers.) |
| 10243 | @end ignore |
| 10244 | @end itemize |
| 10245 | |
| 10246 | Range checking, if turned on, is done on mathematical operations. Array |
| 10247 | indices are not checked, since they are often used to index a pointer |
| 10248 | that is not itself an array. |
| 10249 | |
| 10250 | @node Debugging C |
| 10251 | @subsubsection @value{GDBN} and C |
| 10252 | |
| 10253 | The @code{set print union} and @code{show print union} commands apply to |
| 10254 | the @code{union} type. When set to @samp{on}, any @code{union} that is |
| 10255 | inside a @code{struct} or @code{class} is also printed. Otherwise, it |
| 10256 | appears as @samp{@{...@}}. |
| 10257 | |
| 10258 | The @code{@@} operator aids in the debugging of dynamic arrays, formed |
| 10259 | with pointers and a memory allocation function. @xref{Expressions, |
| 10260 | ,Expressions}. |
| 10261 | |
| 10262 | @node Debugging C Plus Plus |
| 10263 | @subsubsection @value{GDBN} Features for C@t{++} |
| 10264 | |
| 10265 | @cindex commands for C@t{++} |
| 10266 | |
| 10267 | Some @value{GDBN} commands are particularly useful with C@t{++}, and some are |
| 10268 | designed specifically for use with C@t{++}. Here is a summary: |
| 10269 | |
| 10270 | @table @code |
| 10271 | @cindex break in overloaded functions |
| 10272 | @item @r{breakpoint menus} |
| 10273 | When you want a breakpoint in a function whose name is overloaded, |
| 10274 | @value{GDBN} has the capability to display a menu of possible breakpoint |
| 10275 | locations to help you specify which function definition you want. |
| 10276 | @xref{Ambiguous Expressions,,Ambiguous Expressions}. |
| 10277 | |
| 10278 | @cindex overloading in C@t{++} |
| 10279 | @item rbreak @var{regex} |
| 10280 | Setting breakpoints using regular expressions is helpful for setting |
| 10281 | breakpoints on overloaded functions that are not members of any special |
| 10282 | classes. |
| 10283 | @xref{Set Breaks, ,Setting Breakpoints}. |
| 10284 | |
| 10285 | @cindex C@t{++} exception handling |
| 10286 | @item catch throw |
| 10287 | @itemx catch catch |
| 10288 | Debug C@t{++} exception handling using these commands. @xref{Set |
| 10289 | Catchpoints, , Setting Catchpoints}. |
| 10290 | |
| 10291 | @cindex inheritance |
| 10292 | @item ptype @var{typename} |
| 10293 | Print inheritance relationships as well as other information for type |
| 10294 | @var{typename}. |
| 10295 | @xref{Symbols, ,Examining the Symbol Table}. |
| 10296 | |
| 10297 | @cindex C@t{++} symbol display |
| 10298 | @item set print demangle |
| 10299 | @itemx show print demangle |
| 10300 | @itemx set print asm-demangle |
| 10301 | @itemx show print asm-demangle |
| 10302 | Control whether C@t{++} symbols display in their source form, both when |
| 10303 | displaying code as C@t{++} source and when displaying disassemblies. |
| 10304 | @xref{Print Settings, ,Print Settings}. |
| 10305 | |
| 10306 | @item set print object |
| 10307 | @itemx show print object |
| 10308 | Choose whether to print derived (actual) or declared types of objects. |
| 10309 | @xref{Print Settings, ,Print Settings}. |
| 10310 | |
| 10311 | @item set print vtbl |
| 10312 | @itemx show print vtbl |
| 10313 | Control the format for printing virtual function tables. |
| 10314 | @xref{Print Settings, ,Print Settings}. |
| 10315 | (The @code{vtbl} commands do not work on programs compiled with the HP |
| 10316 | ANSI C@t{++} compiler (@code{aCC}).) |
| 10317 | |
| 10318 | @kindex set overload-resolution |
| 10319 | @cindex overloaded functions, overload resolution |
| 10320 | @item set overload-resolution on |
| 10321 | Enable overload resolution for C@t{++} expression evaluation. The default |
| 10322 | is on. For overloaded functions, @value{GDBN} evaluates the arguments |
| 10323 | and searches for a function whose signature matches the argument types, |
| 10324 | using the standard C@t{++} conversion rules (see @ref{C Plus Plus |
| 10325 | Expressions, ,C@t{++} Expressions}, for details). |
| 10326 | If it cannot find a match, it emits a message. |
| 10327 | |
| 10328 | @item set overload-resolution off |
| 10329 | Disable overload resolution for C@t{++} expression evaluation. For |
| 10330 | overloaded functions that are not class member functions, @value{GDBN} |
| 10331 | chooses the first function of the specified name that it finds in the |
| 10332 | symbol table, whether or not its arguments are of the correct type. For |
| 10333 | overloaded functions that are class member functions, @value{GDBN} |
| 10334 | searches for a function whose signature @emph{exactly} matches the |
| 10335 | argument types. |
| 10336 | |
| 10337 | @kindex show overload-resolution |
| 10338 | @item show overload-resolution |
| 10339 | Show the current setting of overload resolution. |
| 10340 | |
| 10341 | @item @r{Overloaded symbol names} |
| 10342 | You can specify a particular definition of an overloaded symbol, using |
| 10343 | the same notation that is used to declare such symbols in C@t{++}: type |
| 10344 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can |
| 10345 | also use the @value{GDBN} command-line word completion facilities to list the |
| 10346 | available choices, or to finish the type list for you. |
| 10347 | @xref{Completion,, Command Completion}, for details on how to do this. |
| 10348 | @end table |
| 10349 | |
| 10350 | @node Decimal Floating Point |
| 10351 | @subsubsection Decimal Floating Point format |
| 10352 | @cindex decimal floating point format |
| 10353 | |
| 10354 | @value{GDBN} can examine, set and perform computations with numbers in |
| 10355 | decimal floating point format, which in the C language correspond to the |
| 10356 | @code{_Decimal32}, @code{_Decimal64} and @code{_Decimal128} types as |
| 10357 | specified by the extension to support decimal floating-point arithmetic. |
| 10358 | |
| 10359 | There are two encodings in use, depending on the architecture: BID (Binary |
| 10360 | Integer Decimal) for x86 and x86-64, and DPD (Densely Packed Decimal) for |
| 10361 | PowerPC. @value{GDBN} will use the appropriate encoding for the configured |
| 10362 | target. |
| 10363 | |
| 10364 | Because of a limitation in @file{libdecnumber}, the library used by @value{GDBN} |
| 10365 | to manipulate decimal floating point numbers, it is not possible to convert |
| 10366 | (using a cast, for example) integers wider than 32-bit to decimal float. |
| 10367 | |
| 10368 | In addition, in order to imitate @value{GDBN}'s behaviour with binary floating |
| 10369 | point computations, error checking in decimal float operations ignores |
| 10370 | underflow, overflow and divide by zero exceptions. |
| 10371 | |
| 10372 | In the PowerPC architecture, @value{GDBN} provides a set of pseudo-registers |
| 10373 | to inspect @code{_Decimal128} values stored in floating point registers. See |
| 10374 | @ref{PowerPC,,PowerPC} for more details. |
| 10375 | |
| 10376 | @node Objective-C |
| 10377 | @subsection Objective-C |
| 10378 | |
| 10379 | @cindex Objective-C |
| 10380 | This section provides information about some commands and command |
| 10381 | options that are useful for debugging Objective-C code. See also |
| 10382 | @ref{Symbols, info classes}, and @ref{Symbols, info selectors}, for a |
| 10383 | few more commands specific to Objective-C support. |
| 10384 | |
| 10385 | @menu |
| 10386 | * Method Names in Commands:: |
| 10387 | * The Print Command with Objective-C:: |
| 10388 | @end menu |
| 10389 | |
| 10390 | @node Method Names in Commands |
| 10391 | @subsubsection Method Names in Commands |
| 10392 | |
| 10393 | The following commands have been extended to accept Objective-C method |
| 10394 | names as line specifications: |
| 10395 | |
| 10396 | @kindex clear@r{, and Objective-C} |
| 10397 | @kindex break@r{, and Objective-C} |
| 10398 | @kindex info line@r{, and Objective-C} |
| 10399 | @kindex jump@r{, and Objective-C} |
| 10400 | @kindex list@r{, and Objective-C} |
| 10401 | @itemize |
| 10402 | @item @code{clear} |
| 10403 | @item @code{break} |
| 10404 | @item @code{info line} |
| 10405 | @item @code{jump} |
| 10406 | @item @code{list} |
| 10407 | @end itemize |
| 10408 | |
| 10409 | A fully qualified Objective-C method name is specified as |
| 10410 | |
| 10411 | @smallexample |
| 10412 | -[@var{Class} @var{methodName}] |
| 10413 | @end smallexample |
| 10414 | |
| 10415 | where the minus sign is used to indicate an instance method and a |
| 10416 | plus sign (not shown) is used to indicate a class method. The class |
| 10417 | name @var{Class} and method name @var{methodName} are enclosed in |
| 10418 | brackets, similar to the way messages are specified in Objective-C |
| 10419 | source code. For example, to set a breakpoint at the @code{create} |
| 10420 | instance method of class @code{Fruit} in the program currently being |
| 10421 | debugged, enter: |
| 10422 | |
| 10423 | @smallexample |
| 10424 | break -[Fruit create] |
| 10425 | @end smallexample |
| 10426 | |
| 10427 | To list ten program lines around the @code{initialize} class method, |
| 10428 | enter: |
| 10429 | |
| 10430 | @smallexample |
| 10431 | list +[NSText initialize] |
| 10432 | @end smallexample |
| 10433 | |
| 10434 | In the current version of @value{GDBN}, the plus or minus sign is |
| 10435 | required. In future versions of @value{GDBN}, the plus or minus |
| 10436 | sign will be optional, but you can use it to narrow the search. It |
| 10437 | is also possible to specify just a method name: |
| 10438 | |
| 10439 | @smallexample |
| 10440 | break create |
| 10441 | @end smallexample |
| 10442 | |
| 10443 | You must specify the complete method name, including any colons. If |
| 10444 | your program's source files contain more than one @code{create} method, |
| 10445 | you'll be presented with a numbered list of classes that implement that |
| 10446 | method. Indicate your choice by number, or type @samp{0} to exit if |
| 10447 | none apply. |
| 10448 | |
| 10449 | As another example, to clear a breakpoint established at the |
| 10450 | @code{makeKeyAndOrderFront:} method of the @code{NSWindow} class, enter: |
| 10451 | |
| 10452 | @smallexample |
| 10453 | clear -[NSWindow makeKeyAndOrderFront:] |
| 10454 | @end smallexample |
| 10455 | |
| 10456 | @node The Print Command with Objective-C |
| 10457 | @subsubsection The Print Command With Objective-C |
| 10458 | @cindex Objective-C, print objects |
| 10459 | @kindex print-object |
| 10460 | @kindex po @r{(@code{print-object})} |
| 10461 | |
| 10462 | The print command has also been extended to accept methods. For example: |
| 10463 | |
| 10464 | @smallexample |
| 10465 | print -[@var{object} hash] |
| 10466 | @end smallexample |
| 10467 | |
| 10468 | @cindex print an Objective-C object description |
| 10469 | @cindex @code{_NSPrintForDebugger}, and printing Objective-C objects |
| 10470 | @noindent |
| 10471 | will tell @value{GDBN} to send the @code{hash} message to @var{object} |
| 10472 | and print the result. Also, an additional command has been added, |
| 10473 | @code{print-object} or @code{po} for short, which is meant to print |
| 10474 | the description of an object. However, this command may only work |
| 10475 | with certain Objective-C libraries that have a particular hook |
| 10476 | function, @code{_NSPrintForDebugger}, defined. |
| 10477 | |
| 10478 | @node Fortran |
| 10479 | @subsection Fortran |
| 10480 | @cindex Fortran-specific support in @value{GDBN} |
| 10481 | |
| 10482 | @value{GDBN} can be used to debug programs written in Fortran, but it |
| 10483 | currently supports only the features of Fortran 77 language. |
| 10484 | |
| 10485 | @cindex trailing underscore, in Fortran symbols |
| 10486 | Some Fortran compilers (@sc{gnu} Fortran 77 and Fortran 95 compilers |
| 10487 | among them) append an underscore to the names of variables and |
| 10488 | functions. When you debug programs compiled by those compilers, you |
| 10489 | will need to refer to variables and functions with a trailing |
| 10490 | underscore. |
| 10491 | |
| 10492 | @menu |
| 10493 | * Fortran Operators:: Fortran operators and expressions |
| 10494 | * Fortran Defaults:: Default settings for Fortran |
| 10495 | * Special Fortran Commands:: Special @value{GDBN} commands for Fortran |
| 10496 | @end menu |
| 10497 | |
| 10498 | @node Fortran Operators |
| 10499 | @subsubsection Fortran Operators and Expressions |
| 10500 | |
| 10501 | @cindex Fortran operators and expressions |
| 10502 | |
| 10503 | Operators must be defined on values of specific types. For instance, |
| 10504 | @code{+} is defined on numbers, but not on characters or other non- |
| 10505 | arithmetic types. Operators are often defined on groups of types. |
| 10506 | |
| 10507 | @table @code |
| 10508 | @item ** |
| 10509 | The exponentiation operator. It raises the first operand to the power |
| 10510 | of the second one. |
| 10511 | |
| 10512 | @item : |
| 10513 | The range operator. Normally used in the form of array(low:high) to |
| 10514 | represent a section of array. |
| 10515 | |
| 10516 | @item % |
| 10517 | The access component operator. Normally used to access elements in derived |
| 10518 | types. Also suitable for unions. As unions aren't part of regular Fortran, |
| 10519 | this can only happen when accessing a register that uses a gdbarch-defined |
| 10520 | union type. |
| 10521 | @end table |
| 10522 | |
| 10523 | @node Fortran Defaults |
| 10524 | @subsubsection Fortran Defaults |
| 10525 | |
| 10526 | @cindex Fortran Defaults |
| 10527 | |
| 10528 | Fortran symbols are usually case-insensitive, so @value{GDBN} by |
| 10529 | default uses case-insensitive matches for Fortran symbols. You can |
| 10530 | change that with the @samp{set case-insensitive} command, see |
| 10531 | @ref{Symbols}, for the details. |
| 10532 | |
| 10533 | @node Special Fortran Commands |
| 10534 | @subsubsection Special Fortran Commands |
| 10535 | |
| 10536 | @cindex Special Fortran commands |
| 10537 | |
| 10538 | @value{GDBN} has some commands to support Fortran-specific features, |
| 10539 | such as displaying common blocks. |
| 10540 | |
| 10541 | @table @code |
| 10542 | @cindex @code{COMMON} blocks, Fortran |
| 10543 | @kindex info common |
| 10544 | @item info common @r{[}@var{common-name}@r{]} |
| 10545 | This command prints the values contained in the Fortran @code{COMMON} |
| 10546 | block whose name is @var{common-name}. With no argument, the names of |
| 10547 | all @code{COMMON} blocks visible at the current program location are |
| 10548 | printed. |
| 10549 | @end table |
| 10550 | |
| 10551 | @node Pascal |
| 10552 | @subsection Pascal |
| 10553 | |
| 10554 | @cindex Pascal support in @value{GDBN}, limitations |
| 10555 | Debugging Pascal programs which use sets, subranges, file variables, or |
| 10556 | nested functions does not currently work. @value{GDBN} does not support |
| 10557 | entering expressions, printing values, or similar features using Pascal |
| 10558 | syntax. |
| 10559 | |
| 10560 | The Pascal-specific command @code{set print pascal_static-members} |
| 10561 | controls whether static members of Pascal objects are displayed. |
| 10562 | @xref{Print Settings, pascal_static-members}. |
| 10563 | |
| 10564 | @node Modula-2 |
| 10565 | @subsection Modula-2 |
| 10566 | |
| 10567 | @cindex Modula-2, @value{GDBN} support |
| 10568 | |
| 10569 | The extensions made to @value{GDBN} to support Modula-2 only support |
| 10570 | output from the @sc{gnu} Modula-2 compiler (which is currently being |
| 10571 | developed). Other Modula-2 compilers are not currently supported, and |
| 10572 | attempting to debug executables produced by them is most likely |
| 10573 | to give an error as @value{GDBN} reads in the executable's symbol |
| 10574 | table. |
| 10575 | |
| 10576 | @cindex expressions in Modula-2 |
| 10577 | @menu |
| 10578 | * M2 Operators:: Built-in operators |
| 10579 | * Built-In Func/Proc:: Built-in functions and procedures |
| 10580 | * M2 Constants:: Modula-2 constants |
| 10581 | * M2 Types:: Modula-2 types |
| 10582 | * M2 Defaults:: Default settings for Modula-2 |
| 10583 | * Deviations:: Deviations from standard Modula-2 |
| 10584 | * M2 Checks:: Modula-2 type and range checks |
| 10585 | * M2 Scope:: The scope operators @code{::} and @code{.} |
| 10586 | * GDB/M2:: @value{GDBN} and Modula-2 |
| 10587 | @end menu |
| 10588 | |
| 10589 | @node M2 Operators |
| 10590 | @subsubsection Operators |
| 10591 | @cindex Modula-2 operators |
| 10592 | |
| 10593 | Operators must be defined on values of specific types. For instance, |
| 10594 | @code{+} is defined on numbers, but not on structures. Operators are |
| 10595 | often defined on groups of types. For the purposes of Modula-2, the |
| 10596 | following definitions hold: |
| 10597 | |
| 10598 | @itemize @bullet |
| 10599 | |
| 10600 | @item |
| 10601 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and |
| 10602 | their subranges. |
| 10603 | |
| 10604 | @item |
| 10605 | @emph{Character types} consist of @code{CHAR} and its subranges. |
| 10606 | |
| 10607 | @item |
| 10608 | @emph{Floating-point types} consist of @code{REAL}. |
| 10609 | |
| 10610 | @item |
| 10611 | @emph{Pointer types} consist of anything declared as @code{POINTER TO |
| 10612 | @var{type}}. |
| 10613 | |
| 10614 | @item |
| 10615 | @emph{Scalar types} consist of all of the above. |
| 10616 | |
| 10617 | @item |
| 10618 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. |
| 10619 | |
| 10620 | @item |
| 10621 | @emph{Boolean types} consist of @code{BOOLEAN}. |
| 10622 | @end itemize |
| 10623 | |
| 10624 | @noindent |
| 10625 | The following operators are supported, and appear in order of |
| 10626 | increasing precedence: |
| 10627 | |
| 10628 | @table @code |
| 10629 | @item , |
| 10630 | Function argument or array index separator. |
| 10631 | |
| 10632 | @item := |
| 10633 | Assignment. The value of @var{var} @code{:=} @var{value} is |
| 10634 | @var{value}. |
| 10635 | |
| 10636 | @item <@r{, }> |
| 10637 | Less than, greater than on integral, floating-point, or enumerated |
| 10638 | types. |
| 10639 | |
| 10640 | @item <=@r{, }>= |
| 10641 | Less than or equal to, greater than or equal to |
| 10642 | on integral, floating-point and enumerated types, or set inclusion on |
| 10643 | set types. Same precedence as @code{<}. |
| 10644 | |
| 10645 | @item =@r{, }<>@r{, }# |
| 10646 | Equality and two ways of expressing inequality, valid on scalar types. |
| 10647 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is |
| 10648 | available for inequality, since @code{#} conflicts with the script |
| 10649 | comment character. |
| 10650 | |
| 10651 | @item IN |
| 10652 | Set membership. Defined on set types and the types of their members. |
| 10653 | Same precedence as @code{<}. |
| 10654 | |
| 10655 | @item OR |
| 10656 | Boolean disjunction. Defined on boolean types. |
| 10657 | |
| 10658 | @item AND@r{, }& |
| 10659 | Boolean conjunction. Defined on boolean types. |
| 10660 | |
| 10661 | @item @@ |
| 10662 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
| 10663 | |
| 10664 | @item +@r{, }- |
| 10665 | Addition and subtraction on integral and floating-point types, or union |
| 10666 | and difference on set types. |
| 10667 | |
| 10668 | @item * |
| 10669 | Multiplication on integral and floating-point types, or set intersection |
| 10670 | on set types. |
| 10671 | |
| 10672 | @item / |
| 10673 | Division on floating-point types, or symmetric set difference on set |
| 10674 | types. Same precedence as @code{*}. |
| 10675 | |
| 10676 | @item DIV@r{, }MOD |
| 10677 | Integer division and remainder. Defined on integral types. Same |
| 10678 | precedence as @code{*}. |
| 10679 | |
| 10680 | @item - |
| 10681 | Negative. Defined on @code{INTEGER} and @code{REAL} data. |
| 10682 | |
| 10683 | @item ^ |
| 10684 | Pointer dereferencing. Defined on pointer types. |
| 10685 | |
| 10686 | @item NOT |
| 10687 | Boolean negation. Defined on boolean types. Same precedence as |
| 10688 | @code{^}. |
| 10689 | |
| 10690 | @item . |
| 10691 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same |
| 10692 | precedence as @code{^}. |
| 10693 | |
| 10694 | @item [] |
| 10695 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. |
| 10696 | |
| 10697 | @item () |
| 10698 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence |
| 10699 | as @code{^}. |
| 10700 | |
| 10701 | @item ::@r{, }. |
| 10702 | @value{GDBN} and Modula-2 scope operators. |
| 10703 | @end table |
| 10704 | |
| 10705 | @quotation |
| 10706 | @emph{Warning:} Set expressions and their operations are not yet supported, so @value{GDBN} |
| 10707 | treats the use of the operator @code{IN}, or the use of operators |
| 10708 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, |
| 10709 | @code{<=}, and @code{>=} on sets as an error. |
| 10710 | @end quotation |
| 10711 | |
| 10712 | |
| 10713 | @node Built-In Func/Proc |
| 10714 | @subsubsection Built-in Functions and Procedures |
| 10715 | @cindex Modula-2 built-ins |
| 10716 | |
| 10717 | Modula-2 also makes available several built-in procedures and functions. |
| 10718 | In describing these, the following metavariables are used: |
| 10719 | |
| 10720 | @table @var |
| 10721 | |
| 10722 | @item a |
| 10723 | represents an @code{ARRAY} variable. |
| 10724 | |
| 10725 | @item c |
| 10726 | represents a @code{CHAR} constant or variable. |
| 10727 | |
| 10728 | @item i |
| 10729 | represents a variable or constant of integral type. |
| 10730 | |
| 10731 | @item m |
| 10732 | represents an identifier that belongs to a set. Generally used in the |
| 10733 | same function with the metavariable @var{s}. The type of @var{s} should |
| 10734 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). |
| 10735 | |
| 10736 | @item n |
| 10737 | represents a variable or constant of integral or floating-point type. |
| 10738 | |
| 10739 | @item r |
| 10740 | represents a variable or constant of floating-point type. |
| 10741 | |
| 10742 | @item t |
| 10743 | represents a type. |
| 10744 | |
| 10745 | @item v |
| 10746 | represents a variable. |
| 10747 | |
| 10748 | @item x |
| 10749 | represents a variable or constant of one of many types. See the |
| 10750 | explanation of the function for details. |
| 10751 | @end table |
| 10752 | |
| 10753 | All Modula-2 built-in procedures also return a result, described below. |
| 10754 | |
| 10755 | @table @code |
| 10756 | @item ABS(@var{n}) |
| 10757 | Returns the absolute value of @var{n}. |
| 10758 | |
| 10759 | @item CAP(@var{c}) |
| 10760 | If @var{c} is a lower case letter, it returns its upper case |
| 10761 | equivalent, otherwise it returns its argument. |
| 10762 | |
| 10763 | @item CHR(@var{i}) |
| 10764 | Returns the character whose ordinal value is @var{i}. |
| 10765 | |
| 10766 | @item DEC(@var{v}) |
| 10767 | Decrements the value in the variable @var{v} by one. Returns the new value. |
| 10768 | |
| 10769 | @item DEC(@var{v},@var{i}) |
| 10770 | Decrements the value in the variable @var{v} by @var{i}. Returns the |
| 10771 | new value. |
| 10772 | |
| 10773 | @item EXCL(@var{m},@var{s}) |
| 10774 | Removes the element @var{m} from the set @var{s}. Returns the new |
| 10775 | set. |
| 10776 | |
| 10777 | @item FLOAT(@var{i}) |
| 10778 | Returns the floating point equivalent of the integer @var{i}. |
| 10779 | |
| 10780 | @item HIGH(@var{a}) |
| 10781 | Returns the index of the last member of @var{a}. |
| 10782 | |
| 10783 | @item INC(@var{v}) |
| 10784 | Increments the value in the variable @var{v} by one. Returns the new value. |
| 10785 | |
| 10786 | @item INC(@var{v},@var{i}) |
| 10787 | Increments the value in the variable @var{v} by @var{i}. Returns the |
| 10788 | new value. |
| 10789 | |
| 10790 | @item INCL(@var{m},@var{s}) |
| 10791 | Adds the element @var{m} to the set @var{s} if it is not already |
| 10792 | there. Returns the new set. |
| 10793 | |
| 10794 | @item MAX(@var{t}) |
| 10795 | Returns the maximum value of the type @var{t}. |
| 10796 | |
| 10797 | @item MIN(@var{t}) |
| 10798 | Returns the minimum value of the type @var{t}. |
| 10799 | |
| 10800 | @item ODD(@var{i}) |
| 10801 | Returns boolean TRUE if @var{i} is an odd number. |
| 10802 | |
| 10803 | @item ORD(@var{x}) |
| 10804 | Returns the ordinal value of its argument. For example, the ordinal |
| 10805 | value of a character is its @sc{ascii} value (on machines supporting the |
| 10806 | @sc{ascii} character set). @var{x} must be of an ordered type, which include |
| 10807 | integral, character and enumerated types. |
| 10808 | |
| 10809 | @item SIZE(@var{x}) |
| 10810 | Returns the size of its argument. @var{x} can be a variable or a type. |
| 10811 | |
| 10812 | @item TRUNC(@var{r}) |
| 10813 | Returns the integral part of @var{r}. |
| 10814 | |
| 10815 | @item TSIZE(@var{x}) |
| 10816 | Returns the size of its argument. @var{x} can be a variable or a type. |
| 10817 | |
| 10818 | @item VAL(@var{t},@var{i}) |
| 10819 | Returns the member of the type @var{t} whose ordinal value is @var{i}. |
| 10820 | @end table |
| 10821 | |
| 10822 | @quotation |
| 10823 | @emph{Warning:} Sets and their operations are not yet supported, so |
| 10824 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as |
| 10825 | an error. |
| 10826 | @end quotation |
| 10827 | |
| 10828 | @cindex Modula-2 constants |
| 10829 | @node M2 Constants |
| 10830 | @subsubsection Constants |
| 10831 | |
| 10832 | @value{GDBN} allows you to express the constants of Modula-2 in the following |
| 10833 | ways: |
| 10834 | |
| 10835 | @itemize @bullet |
| 10836 | |
| 10837 | @item |
| 10838 | Integer constants are simply a sequence of digits. When used in an |
| 10839 | expression, a constant is interpreted to be type-compatible with the |
| 10840 | rest of the expression. Hexadecimal integers are specified by a |
| 10841 | trailing @samp{H}, and octal integers by a trailing @samp{B}. |
| 10842 | |
| 10843 | @item |
| 10844 | Floating point constants appear as a sequence of digits, followed by a |
| 10845 | decimal point and another sequence of digits. An optional exponent can |
| 10846 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where |
| 10847 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the |
| 10848 | digits of the floating point constant must be valid decimal (base 10) |
| 10849 | digits. |
| 10850 | |
| 10851 | @item |
| 10852 | Character constants consist of a single character enclosed by a pair of |
| 10853 | like quotes, either single (@code{'}) or double (@code{"}). They may |
| 10854 | also be expressed by their ordinal value (their @sc{ascii} value, usually) |
| 10855 | followed by a @samp{C}. |
| 10856 | |
| 10857 | @item |
| 10858 | String constants consist of a sequence of characters enclosed by a |
| 10859 | pair of like quotes, either single (@code{'}) or double (@code{"}). |
| 10860 | Escape sequences in the style of C are also allowed. @xref{C |
| 10861 | Constants, ,C and C@t{++} Constants}, for a brief explanation of escape |
| 10862 | sequences. |
| 10863 | |
| 10864 | @item |
| 10865 | Enumerated constants consist of an enumerated identifier. |
| 10866 | |
| 10867 | @item |
| 10868 | Boolean constants consist of the identifiers @code{TRUE} and |
| 10869 | @code{FALSE}. |
| 10870 | |
| 10871 | @item |
| 10872 | Pointer constants consist of integral values only. |
| 10873 | |
| 10874 | @item |
| 10875 | Set constants are not yet supported. |
| 10876 | @end itemize |
| 10877 | |
| 10878 | @node M2 Types |
| 10879 | @subsubsection Modula-2 Types |
| 10880 | @cindex Modula-2 types |
| 10881 | |
| 10882 | Currently @value{GDBN} can print the following data types in Modula-2 |
| 10883 | syntax: array types, record types, set types, pointer types, procedure |
| 10884 | types, enumerated types, subrange types and base types. You can also |
| 10885 | print the contents of variables declared using these type. |
| 10886 | This section gives a number of simple source code examples together with |
| 10887 | sample @value{GDBN} sessions. |
| 10888 | |
| 10889 | The first example contains the following section of code: |
| 10890 | |
| 10891 | @smallexample |
| 10892 | VAR |
| 10893 | s: SET OF CHAR ; |
| 10894 | r: [20..40] ; |
| 10895 | @end smallexample |
| 10896 | |
| 10897 | @noindent |
| 10898 | and you can request @value{GDBN} to interrogate the type and value of |
| 10899 | @code{r} and @code{s}. |
| 10900 | |
| 10901 | @smallexample |
| 10902 | (@value{GDBP}) print s |
| 10903 | @{'A'..'C', 'Z'@} |
| 10904 | (@value{GDBP}) ptype s |
| 10905 | SET OF CHAR |
| 10906 | (@value{GDBP}) print r |
| 10907 | 21 |
| 10908 | (@value{GDBP}) ptype r |
| 10909 | [20..40] |
| 10910 | @end smallexample |
| 10911 | |
| 10912 | @noindent |
| 10913 | Likewise if your source code declares @code{s} as: |
| 10914 | |
| 10915 | @smallexample |
| 10916 | VAR |
| 10917 | s: SET ['A'..'Z'] ; |
| 10918 | @end smallexample |
| 10919 | |
| 10920 | @noindent |
| 10921 | then you may query the type of @code{s} by: |
| 10922 | |
| 10923 | @smallexample |
| 10924 | (@value{GDBP}) ptype s |
| 10925 | type = SET ['A'..'Z'] |
| 10926 | @end smallexample |
| 10927 | |
| 10928 | @noindent |
| 10929 | Note that at present you cannot interactively manipulate set |
| 10930 | expressions using the debugger. |
| 10931 | |
| 10932 | The following example shows how you might declare an array in Modula-2 |
| 10933 | and how you can interact with @value{GDBN} to print its type and contents: |
| 10934 | |
| 10935 | @smallexample |
| 10936 | VAR |
| 10937 | s: ARRAY [-10..10] OF CHAR ; |
| 10938 | @end smallexample |
| 10939 | |
| 10940 | @smallexample |
| 10941 | (@value{GDBP}) ptype s |
| 10942 | ARRAY [-10..10] OF CHAR |
| 10943 | @end smallexample |
| 10944 | |
| 10945 | Note that the array handling is not yet complete and although the type |
| 10946 | is printed correctly, expression handling still assumes that all |
| 10947 | arrays have a lower bound of zero and not @code{-10} as in the example |
| 10948 | above. |
| 10949 | |
| 10950 | Here are some more type related Modula-2 examples: |
| 10951 | |
| 10952 | @smallexample |
| 10953 | TYPE |
| 10954 | colour = (blue, red, yellow, green) ; |
| 10955 | t = [blue..yellow] ; |
| 10956 | VAR |
| 10957 | s: t ; |
| 10958 | BEGIN |
| 10959 | s := blue ; |
| 10960 | @end smallexample |
| 10961 | |
| 10962 | @noindent |
| 10963 | The @value{GDBN} interaction shows how you can query the data type |
| 10964 | and value of a variable. |
| 10965 | |
| 10966 | @smallexample |
| 10967 | (@value{GDBP}) print s |
| 10968 | $1 = blue |
| 10969 | (@value{GDBP}) ptype t |
| 10970 | type = [blue..yellow] |
| 10971 | @end smallexample |
| 10972 | |
| 10973 | @noindent |
| 10974 | In this example a Modula-2 array is declared and its contents |
| 10975 | displayed. Observe that the contents are written in the same way as |
| 10976 | their @code{C} counterparts. |
| 10977 | |
| 10978 | @smallexample |
| 10979 | VAR |
| 10980 | s: ARRAY [1..5] OF CARDINAL ; |
| 10981 | BEGIN |
| 10982 | s[1] := 1 ; |
| 10983 | @end smallexample |
| 10984 | |
| 10985 | @smallexample |
| 10986 | (@value{GDBP}) print s |
| 10987 | $1 = @{1, 0, 0, 0, 0@} |
| 10988 | (@value{GDBP}) ptype s |
| 10989 | type = ARRAY [1..5] OF CARDINAL |
| 10990 | @end smallexample |
| 10991 | |
| 10992 | The Modula-2 language interface to @value{GDBN} also understands |
| 10993 | pointer types as shown in this example: |
| 10994 | |
| 10995 | @smallexample |
| 10996 | VAR |
| 10997 | s: POINTER TO ARRAY [1..5] OF CARDINAL ; |
| 10998 | BEGIN |
| 10999 | NEW(s) ; |
| 11000 | s^[1] := 1 ; |
| 11001 | @end smallexample |
| 11002 | |
| 11003 | @noindent |
| 11004 | and you can request that @value{GDBN} describes the type of @code{s}. |
| 11005 | |
| 11006 | @smallexample |
| 11007 | (@value{GDBP}) ptype s |
| 11008 | type = POINTER TO ARRAY [1..5] OF CARDINAL |
| 11009 | @end smallexample |
| 11010 | |
| 11011 | @value{GDBN} handles compound types as we can see in this example. |
| 11012 | Here we combine array types, record types, pointer types and subrange |
| 11013 | types: |
| 11014 | |
| 11015 | @smallexample |
| 11016 | TYPE |
| 11017 | foo = RECORD |
| 11018 | f1: CARDINAL ; |
| 11019 | f2: CHAR ; |
| 11020 | f3: myarray ; |
| 11021 | END ; |
| 11022 | |
| 11023 | myarray = ARRAY myrange OF CARDINAL ; |
| 11024 | myrange = [-2..2] ; |
| 11025 | VAR |
| 11026 | s: POINTER TO ARRAY myrange OF foo ; |
| 11027 | @end smallexample |
| 11028 | |
| 11029 | @noindent |
| 11030 | and you can ask @value{GDBN} to describe the type of @code{s} as shown |
| 11031 | below. |
| 11032 | |
| 11033 | @smallexample |
| 11034 | (@value{GDBP}) ptype s |
| 11035 | type = POINTER TO ARRAY [-2..2] OF foo = RECORD |
| 11036 | f1 : CARDINAL; |
| 11037 | f2 : CHAR; |
| 11038 | f3 : ARRAY [-2..2] OF CARDINAL; |
| 11039 | END |
| 11040 | @end smallexample |
| 11041 | |
| 11042 | @node M2 Defaults |
| 11043 | @subsubsection Modula-2 Defaults |
| 11044 | @cindex Modula-2 defaults |
| 11045 | |
| 11046 | If type and range checking are set automatically by @value{GDBN}, they |
| 11047 | both default to @code{on} whenever the working language changes to |
| 11048 | Modula-2. This happens regardless of whether you or @value{GDBN} |
| 11049 | selected the working language. |
| 11050 | |
| 11051 | If you allow @value{GDBN} to set the language automatically, then entering |
| 11052 | code compiled from a file whose name ends with @file{.mod} sets the |
| 11053 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} |
| 11054 | Infer the Source Language}, for further details. |
| 11055 | |
| 11056 | @node Deviations |
| 11057 | @subsubsection Deviations from Standard Modula-2 |
| 11058 | @cindex Modula-2, deviations from |
| 11059 | |
| 11060 | A few changes have been made to make Modula-2 programs easier to debug. |
| 11061 | This is done primarily via loosening its type strictness: |
| 11062 | |
| 11063 | @itemize @bullet |
| 11064 | @item |
| 11065 | Unlike in standard Modula-2, pointer constants can be formed by |
| 11066 | integers. This allows you to modify pointer variables during |
| 11067 | debugging. (In standard Modula-2, the actual address contained in a |
| 11068 | pointer variable is hidden from you; it can only be modified |
| 11069 | through direct assignment to another pointer variable or expression that |
| 11070 | returned a pointer.) |
| 11071 | |
| 11072 | @item |
| 11073 | C escape sequences can be used in strings and characters to represent |
| 11074 | non-printable characters. @value{GDBN} prints out strings with these |
| 11075 | escape sequences embedded. Single non-printable characters are |
| 11076 | printed using the @samp{CHR(@var{nnn})} format. |
| 11077 | |
| 11078 | @item |
| 11079 | The assignment operator (@code{:=}) returns the value of its right-hand |
| 11080 | argument. |
| 11081 | |
| 11082 | @item |
| 11083 | All built-in procedures both modify @emph{and} return their argument. |
| 11084 | @end itemize |
| 11085 | |
| 11086 | @node M2 Checks |
| 11087 | @subsubsection Modula-2 Type and Range Checks |
| 11088 | @cindex Modula-2 checks |
| 11089 | |
| 11090 | @quotation |
| 11091 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or |
| 11092 | range checking. |
| 11093 | @end quotation |
| 11094 | @c FIXME remove warning when type/range checks added |
| 11095 | |
| 11096 | @value{GDBN} considers two Modula-2 variables type equivalent if: |
| 11097 | |
| 11098 | @itemize @bullet |
| 11099 | @item |
| 11100 | They are of types that have been declared equivalent via a @code{TYPE |
| 11101 | @var{t1} = @var{t2}} statement |
| 11102 | |
| 11103 | @item |
| 11104 | They have been declared on the same line. (Note: This is true of the |
| 11105 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) |
| 11106 | @end itemize |
| 11107 | |
| 11108 | As long as type checking is enabled, any attempt to combine variables |
| 11109 | whose types are not equivalent is an error. |
| 11110 | |
| 11111 | Range checking is done on all mathematical operations, assignment, array |
| 11112 | index bounds, and all built-in functions and procedures. |
| 11113 | |
| 11114 | @node M2 Scope |
| 11115 | @subsubsection The Scope Operators @code{::} and @code{.} |
| 11116 | @cindex scope |
| 11117 | @cindex @code{.}, Modula-2 scope operator |
| 11118 | @cindex colon, doubled as scope operator |
| 11119 | @ifinfo |
| 11120 | @vindex colon-colon@r{, in Modula-2} |
| 11121 | @c Info cannot handle :: but TeX can. |
| 11122 | @end ifinfo |
| 11123 | @ifnotinfo |
| 11124 | @vindex ::@r{, in Modula-2} |
| 11125 | @end ifnotinfo |
| 11126 | |
| 11127 | There are a few subtle differences between the Modula-2 scope operator |
| 11128 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have |
| 11129 | similar syntax: |
| 11130 | |
| 11131 | @smallexample |
| 11132 | |
| 11133 | @var{module} . @var{id} |
| 11134 | @var{scope} :: @var{id} |
| 11135 | @end smallexample |
| 11136 | |
| 11137 | @noindent |
| 11138 | where @var{scope} is the name of a module or a procedure, |
| 11139 | @var{module} the name of a module, and @var{id} is any declared |
| 11140 | identifier within your program, except another module. |
| 11141 | |
| 11142 | Using the @code{::} operator makes @value{GDBN} search the scope |
| 11143 | specified by @var{scope} for the identifier @var{id}. If it is not |
| 11144 | found in the specified scope, then @value{GDBN} searches all scopes |
| 11145 | enclosing the one specified by @var{scope}. |
| 11146 | |
| 11147 | Using the @code{.} operator makes @value{GDBN} search the current scope for |
| 11148 | the identifier specified by @var{id} that was imported from the |
| 11149 | definition module specified by @var{module}. With this operator, it is |
| 11150 | an error if the identifier @var{id} was not imported from definition |
| 11151 | module @var{module}, or if @var{id} is not an identifier in |
| 11152 | @var{module}. |
| 11153 | |
| 11154 | @node GDB/M2 |
| 11155 | @subsubsection @value{GDBN} and Modula-2 |
| 11156 | |
| 11157 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. |
| 11158 | Five subcommands of @code{set print} and @code{show print} apply |
| 11159 | specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle}, |
| 11160 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four |
| 11161 | apply to C@t{++}, and the last to the C @code{union} type, which has no direct |
| 11162 | analogue in Modula-2. |
| 11163 | |
| 11164 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available |
| 11165 | with any language, is not useful with Modula-2. Its |
| 11166 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be |
| 11167 | created in Modula-2 as they can in C or C@t{++}. However, because an |
| 11168 | address can be specified by an integral constant, the construct |
| 11169 | @samp{@{@var{type}@}@var{adrexp}} is still useful. |
| 11170 | |
| 11171 | @cindex @code{#} in Modula-2 |
| 11172 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is |
| 11173 | interpreted as the beginning of a comment. Use @code{<>} instead. |
| 11174 | |
| 11175 | @node Ada |
| 11176 | @subsection Ada |
| 11177 | @cindex Ada |
| 11178 | |
| 11179 | The extensions made to @value{GDBN} for Ada only support |
| 11180 | output from the @sc{gnu} Ada (GNAT) compiler. |
| 11181 | Other Ada compilers are not currently supported, and |
| 11182 | attempting to debug executables produced by them is most likely |
| 11183 | to be difficult. |
| 11184 | |
| 11185 | |
| 11186 | @cindex expressions in Ada |
| 11187 | @menu |
| 11188 | * Ada Mode Intro:: General remarks on the Ada syntax |
| 11189 | and semantics supported by Ada mode |
| 11190 | in @value{GDBN}. |
| 11191 | * Omissions from Ada:: Restrictions on the Ada expression syntax. |
| 11192 | * Additions to Ada:: Extensions of the Ada expression syntax. |
| 11193 | * Stopping Before Main Program:: Debugging the program during elaboration. |
| 11194 | * Ada Tasks:: Listing and setting breakpoints in tasks. |
| 11195 | * Ada Tasks and Core Files:: Tasking Support when Debugging Core Files |
| 11196 | * Ada Glitches:: Known peculiarities of Ada mode. |
| 11197 | @end menu |
| 11198 | |
| 11199 | @node Ada Mode Intro |
| 11200 | @subsubsection Introduction |
| 11201 | @cindex Ada mode, general |
| 11202 | |
| 11203 | The Ada mode of @value{GDBN} supports a fairly large subset of Ada expression |
| 11204 | syntax, with some extensions. |
| 11205 | The philosophy behind the design of this subset is |
| 11206 | |
| 11207 | @itemize @bullet |
| 11208 | @item |
| 11209 | That @value{GDBN} should provide basic literals and access to operations for |
| 11210 | arithmetic, dereferencing, field selection, indexing, and subprogram calls, |
| 11211 | leaving more sophisticated computations to subprograms written into the |
| 11212 | program (which therefore may be called from @value{GDBN}). |
| 11213 | |
| 11214 | @item |
| 11215 | That type safety and strict adherence to Ada language restrictions |
| 11216 | are not particularly important to the @value{GDBN} user. |
| 11217 | |
| 11218 | @item |
| 11219 | That brevity is important to the @value{GDBN} user. |
| 11220 | @end itemize |
| 11221 | |
| 11222 | Thus, for brevity, the debugger acts as if all names declared in |
| 11223 | user-written packages are directly visible, even if they are not visible |
| 11224 | according to Ada rules, thus making it unnecessary to fully qualify most |
| 11225 | names with their packages, regardless of context. Where this causes |
| 11226 | ambiguity, @value{GDBN} asks the user's intent. |
| 11227 | |
| 11228 | The debugger will start in Ada mode if it detects an Ada main program. |
| 11229 | As for other languages, it will enter Ada mode when stopped in a program that |
| 11230 | was translated from an Ada source file. |
| 11231 | |
| 11232 | While in Ada mode, you may use `@t{--}' for comments. This is useful |
| 11233 | mostly for documenting command files. The standard @value{GDBN} comment |
| 11234 | (@samp{#}) still works at the beginning of a line in Ada mode, but not in the |
| 11235 | middle (to allow based literals). |
| 11236 | |
| 11237 | The debugger supports limited overloading. Given a subprogram call in which |
| 11238 | the function symbol has multiple definitions, it will use the number of |
| 11239 | actual parameters and some information about their types to attempt to narrow |
| 11240 | the set of definitions. It also makes very limited use of context, preferring |
| 11241 | procedures to functions in the context of the @code{call} command, and |
| 11242 | functions to procedures elsewhere. |
| 11243 | |
| 11244 | @node Omissions from Ada |
| 11245 | @subsubsection Omissions from Ada |
| 11246 | @cindex Ada, omissions from |
| 11247 | |
| 11248 | Here are the notable omissions from the subset: |
| 11249 | |
| 11250 | @itemize @bullet |
| 11251 | @item |
| 11252 | Only a subset of the attributes are supported: |
| 11253 | |
| 11254 | @itemize @minus |
| 11255 | @item |
| 11256 | @t{'First}, @t{'Last}, and @t{'Length} |
| 11257 | on array objects (not on types and subtypes). |
| 11258 | |
| 11259 | @item |
| 11260 | @t{'Min} and @t{'Max}. |
| 11261 | |
| 11262 | @item |
| 11263 | @t{'Pos} and @t{'Val}. |
| 11264 | |
| 11265 | @item |
| 11266 | @t{'Tag}. |
| 11267 | |
| 11268 | @item |
| 11269 | @t{'Range} on array objects (not subtypes), but only as the right |
| 11270 | operand of the membership (@code{in}) operator. |
| 11271 | |
| 11272 | @item |
| 11273 | @t{'Access}, @t{'Unchecked_Access}, and |
| 11274 | @t{'Unrestricted_Access} (a GNAT extension). |
| 11275 | |
| 11276 | @item |
| 11277 | @t{'Address}. |
| 11278 | @end itemize |
| 11279 | |
| 11280 | @item |
| 11281 | The names in |
| 11282 | @code{Characters.Latin_1} are not available and |
| 11283 | concatenation is not implemented. Thus, escape characters in strings are |
| 11284 | not currently available. |
| 11285 | |
| 11286 | @item |
| 11287 | Equality tests (@samp{=} and @samp{/=}) on arrays test for bitwise |
| 11288 | equality of representations. They will generally work correctly |
| 11289 | for strings and arrays whose elements have integer or enumeration types. |
| 11290 | They may not work correctly for arrays whose element |
| 11291 | types have user-defined equality, for arrays of real values |
| 11292 | (in particular, IEEE-conformant floating point, because of negative |
| 11293 | zeroes and NaNs), and for arrays whose elements contain unused bits with |
| 11294 | indeterminate values. |
| 11295 | |
| 11296 | @item |
| 11297 | The other component-by-component array operations (@code{and}, @code{or}, |
| 11298 | @code{xor}, @code{not}, and relational tests other than equality) |
| 11299 | are not implemented. |
| 11300 | |
| 11301 | @item |
| 11302 | @cindex array aggregates (Ada) |
| 11303 | @cindex record aggregates (Ada) |
| 11304 | @cindex aggregates (Ada) |
| 11305 | There is limited support for array and record aggregates. They are |
| 11306 | permitted only on the right sides of assignments, as in these examples: |
| 11307 | |
| 11308 | @smallexample |
| 11309 | (@value{GDBP}) set An_Array := (1, 2, 3, 4, 5, 6) |
| 11310 | (@value{GDBP}) set An_Array := (1, others => 0) |
| 11311 | (@value{GDBP}) set An_Array := (0|4 => 1, 1..3 => 2, 5 => 6) |
| 11312 | (@value{GDBP}) set A_2D_Array := ((1, 2, 3), (4, 5, 6), (7, 8, 9)) |
| 11313 | (@value{GDBP}) set A_Record := (1, "Peter", True); |
| 11314 | (@value{GDBP}) set A_Record := (Name => "Peter", Id => 1, Alive => True) |
| 11315 | @end smallexample |
| 11316 | |
| 11317 | Changing a |
| 11318 | discriminant's value by assigning an aggregate has an |
| 11319 | undefined effect if that discriminant is used within the record. |
| 11320 | However, you can first modify discriminants by directly assigning to |
| 11321 | them (which normally would not be allowed in Ada), and then performing an |
| 11322 | aggregate assignment. For example, given a variable @code{A_Rec} |
| 11323 | declared to have a type such as: |
| 11324 | |
| 11325 | @smallexample |
| 11326 | type Rec (Len : Small_Integer := 0) is record |
| 11327 | Id : Integer; |
| 11328 | Vals : IntArray (1 .. Len); |
| 11329 | end record; |
| 11330 | @end smallexample |
| 11331 | |
| 11332 | you can assign a value with a different size of @code{Vals} with two |
| 11333 | assignments: |
| 11334 | |
| 11335 | @smallexample |
| 11336 | (@value{GDBP}) set A_Rec.Len := 4 |
| 11337 | (@value{GDBP}) set A_Rec := (Id => 42, Vals => (1, 2, 3, 4)) |
| 11338 | @end smallexample |
| 11339 | |
| 11340 | As this example also illustrates, @value{GDBN} is very loose about the usual |
| 11341 | rules concerning aggregates. You may leave out some of the |
| 11342 | components of an array or record aggregate (such as the @code{Len} |
| 11343 | component in the assignment to @code{A_Rec} above); they will retain their |
| 11344 | original values upon assignment. You may freely use dynamic values as |
| 11345 | indices in component associations. You may even use overlapping or |
| 11346 | redundant component associations, although which component values are |
| 11347 | assigned in such cases is not defined. |
| 11348 | |
| 11349 | @item |
| 11350 | Calls to dispatching subprograms are not implemented. |
| 11351 | |
| 11352 | @item |
| 11353 | The overloading algorithm is much more limited (i.e., less selective) |
| 11354 | than that of real Ada. It makes only limited use of the context in |
| 11355 | which a subexpression appears to resolve its meaning, and it is much |
| 11356 | looser in its rules for allowing type matches. As a result, some |
| 11357 | function calls will be ambiguous, and the user will be asked to choose |
| 11358 | the proper resolution. |
| 11359 | |
| 11360 | @item |
| 11361 | The @code{new} operator is not implemented. |
| 11362 | |
| 11363 | @item |
| 11364 | Entry calls are not implemented. |
| 11365 | |
| 11366 | @item |
| 11367 | Aside from printing, arithmetic operations on the native VAX floating-point |
| 11368 | formats are not supported. |
| 11369 | |
| 11370 | @item |
| 11371 | It is not possible to slice a packed array. |
| 11372 | |
| 11373 | @item |
| 11374 | The names @code{True} and @code{False}, when not part of a qualified name, |
| 11375 | are interpreted as if implicitly prefixed by @code{Standard}, regardless of |
| 11376 | context. |
| 11377 | Should your program |
| 11378 | redefine these names in a package or procedure (at best a dubious practice), |
| 11379 | you will have to use fully qualified names to access their new definitions. |
| 11380 | @end itemize |
| 11381 | |
| 11382 | @node Additions to Ada |
| 11383 | @subsubsection Additions to Ada |
| 11384 | @cindex Ada, deviations from |
| 11385 | |
| 11386 | As it does for other languages, @value{GDBN} makes certain generic |
| 11387 | extensions to Ada (@pxref{Expressions}): |
| 11388 | |
| 11389 | @itemize @bullet |
| 11390 | @item |
| 11391 | If the expression @var{E} is a variable residing in memory (typically |
| 11392 | a local variable or array element) and @var{N} is a positive integer, |
| 11393 | then @code{@var{E}@@@var{N}} displays the values of @var{E} and the |
| 11394 | @var{N}-1 adjacent variables following it in memory as an array. In |
| 11395 | Ada, this operator is generally not necessary, since its prime use is |
| 11396 | in displaying parts of an array, and slicing will usually do this in |
| 11397 | Ada. However, there are occasional uses when debugging programs in |
| 11398 | which certain debugging information has been optimized away. |
| 11399 | |
| 11400 | @item |
| 11401 | @code{@var{B}::@var{var}} means ``the variable named @var{var} that |
| 11402 | appears in function or file @var{B}.'' When @var{B} is a file name, |
| 11403 | you must typically surround it in single quotes. |
| 11404 | |
| 11405 | @item |
| 11406 | The expression @code{@{@var{type}@} @var{addr}} means ``the variable of type |
| 11407 | @var{type} that appears at address @var{addr}.'' |
| 11408 | |
| 11409 | @item |
| 11410 | A name starting with @samp{$} is a convenience variable |
| 11411 | (@pxref{Convenience Vars}) or a machine register (@pxref{Registers}). |
| 11412 | @end itemize |
| 11413 | |
| 11414 | In addition, @value{GDBN} provides a few other shortcuts and outright |
| 11415 | additions specific to Ada: |
| 11416 | |
| 11417 | @itemize @bullet |
| 11418 | @item |
| 11419 | The assignment statement is allowed as an expression, returning |
| 11420 | its right-hand operand as its value. Thus, you may enter |
| 11421 | |
| 11422 | @smallexample |
| 11423 | (@value{GDBP}) set x := y + 3 |
| 11424 | (@value{GDBP}) print A(tmp := y + 1) |
| 11425 | @end smallexample |
| 11426 | |
| 11427 | @item |
| 11428 | The semicolon is allowed as an ``operator,'' returning as its value |
| 11429 | the value of its right-hand operand. |
| 11430 | This allows, for example, |
| 11431 | complex conditional breaks: |
| 11432 | |
| 11433 | @smallexample |
| 11434 | (@value{GDBP}) break f |
| 11435 | (@value{GDBP}) condition 1 (report(i); k += 1; A(k) > 100) |
| 11436 | @end smallexample |
| 11437 | |
| 11438 | @item |
| 11439 | Rather than use catenation and symbolic character names to introduce special |
| 11440 | characters into strings, one may instead use a special bracket notation, |
| 11441 | which is also used to print strings. A sequence of characters of the form |
| 11442 | @samp{["@var{XX}"]} within a string or character literal denotes the |
| 11443 | (single) character whose numeric encoding is @var{XX} in hexadecimal. The |
| 11444 | sequence of characters @samp{["""]} also denotes a single quotation mark |
| 11445 | in strings. For example, |
| 11446 | @smallexample |
| 11447 | "One line.["0a"]Next line.["0a"]" |
| 11448 | @end smallexample |
| 11449 | @noindent |
| 11450 | contains an ASCII newline character (@code{Ada.Characters.Latin_1.LF}) |
| 11451 | after each period. |
| 11452 | |
| 11453 | @item |
| 11454 | The subtype used as a prefix for the attributes @t{'Pos}, @t{'Min}, and |
| 11455 | @t{'Max} is optional (and is ignored in any case). For example, it is valid |
| 11456 | to write |
| 11457 | |
| 11458 | @smallexample |
| 11459 | (@value{GDBP}) print 'max(x, y) |
| 11460 | @end smallexample |
| 11461 | |
| 11462 | @item |
| 11463 | When printing arrays, @value{GDBN} uses positional notation when the |
| 11464 | array has a lower bound of 1, and uses a modified named notation otherwise. |
| 11465 | For example, a one-dimensional array of three integers with a lower bound |
| 11466 | of 3 might print as |
| 11467 | |
| 11468 | @smallexample |
| 11469 | (3 => 10, 17, 1) |
| 11470 | @end smallexample |
| 11471 | |
| 11472 | @noindent |
| 11473 | That is, in contrast to valid Ada, only the first component has a @code{=>} |
| 11474 | clause. |
| 11475 | |
| 11476 | @item |
| 11477 | You may abbreviate attributes in expressions with any unique, |
| 11478 | multi-character subsequence of |
| 11479 | their names (an exact match gets preference). |
| 11480 | For example, you may use @t{a'len}, @t{a'gth}, or @t{a'lh} |
| 11481 | in place of @t{a'length}. |
| 11482 | |
| 11483 | @item |
| 11484 | @cindex quoting Ada internal identifiers |
| 11485 | Since Ada is case-insensitive, the debugger normally maps identifiers you type |
| 11486 | to lower case. The GNAT compiler uses upper-case characters for |
| 11487 | some of its internal identifiers, which are normally of no interest to users. |
| 11488 | For the rare occasions when you actually have to look at them, |
| 11489 | enclose them in angle brackets to avoid the lower-case mapping. |
| 11490 | For example, |
| 11491 | @smallexample |
| 11492 | (@value{GDBP}) print <JMPBUF_SAVE>[0] |
| 11493 | @end smallexample |
| 11494 | |
| 11495 | @item |
| 11496 | Printing an object of class-wide type or dereferencing an |
| 11497 | access-to-class-wide value will display all the components of the object's |
| 11498 | specific type (as indicated by its run-time tag). Likewise, component |
| 11499 | selection on such a value will operate on the specific type of the |
| 11500 | object. |
| 11501 | |
| 11502 | @end itemize |
| 11503 | |
| 11504 | @node Stopping Before Main Program |
| 11505 | @subsubsection Stopping at the Very Beginning |
| 11506 | |
| 11507 | @cindex breakpointing Ada elaboration code |
| 11508 | It is sometimes necessary to debug the program during elaboration, and |
| 11509 | before reaching the main procedure. |
| 11510 | As defined in the Ada Reference |
| 11511 | Manual, the elaboration code is invoked from a procedure called |
| 11512 | @code{adainit}. To run your program up to the beginning of |
| 11513 | elaboration, simply use the following two commands: |
| 11514 | @code{tbreak adainit} and @code{run}. |
| 11515 | |
| 11516 | @node Ada Tasks |
| 11517 | @subsubsection Extensions for Ada Tasks |
| 11518 | @cindex Ada, tasking |
| 11519 | |
| 11520 | Support for Ada tasks is analogous to that for threads (@pxref{Threads}). |
| 11521 | @value{GDBN} provides the following task-related commands: |
| 11522 | |
| 11523 | @table @code |
| 11524 | @kindex info tasks |
| 11525 | @item info tasks |
| 11526 | This command shows a list of current Ada tasks, as in the following example: |
| 11527 | |
| 11528 | |
| 11529 | @smallexample |
| 11530 | @iftex |
| 11531 | @leftskip=0.5cm |
| 11532 | @end iftex |
| 11533 | (@value{GDBP}) info tasks |
| 11534 | ID TID P-ID Pri State Name |
| 11535 | 1 8088000 0 15 Child Activation Wait main_task |
| 11536 | 2 80a4000 1 15 Accept Statement b |
| 11537 | 3 809a800 1 15 Child Activation Wait a |
| 11538 | * 4 80ae800 3 15 Running c |
| 11539 | |
| 11540 | @end smallexample |
| 11541 | |
| 11542 | @noindent |
| 11543 | In this listing, the asterisk before the last task indicates it to be the |
| 11544 | task currently being inspected. |
| 11545 | |
| 11546 | @table @asis |
| 11547 | @item ID |
| 11548 | Represents @value{GDBN}'s internal task number. |
| 11549 | |
| 11550 | @item TID |
| 11551 | The Ada task ID. |
| 11552 | |
| 11553 | @item P-ID |
| 11554 | The parent's task ID (@value{GDBN}'s internal task number). |
| 11555 | |
| 11556 | @item Pri |
| 11557 | The base priority of the task. |
| 11558 | |
| 11559 | @item State |
| 11560 | Current state of the task. |
| 11561 | |
| 11562 | @table @code |
| 11563 | @item Unactivated |
| 11564 | The task has been created but has not been activated. It cannot be |
| 11565 | executing. |
| 11566 | |
| 11567 | @item Running |
| 11568 | The task currently running. |
| 11569 | |
| 11570 | @item Runnable |
| 11571 | The task is not blocked for any reason known to Ada. (It may be waiting |
| 11572 | for a mutex, though.) It is conceptually "executing" in normal mode. |
| 11573 | |
| 11574 | @item Terminated |
| 11575 | The task is terminated, in the sense of ARM 9.3 (5). Any dependents |
| 11576 | that were waiting on terminate alternatives have been awakened and have |
| 11577 | terminated themselves. |
| 11578 | |
| 11579 | @item Child Activation Wait |
| 11580 | The task is waiting for created tasks to complete activation. |
| 11581 | |
| 11582 | @item Accept Statement |
| 11583 | The task is waiting on an accept or selective wait statement. |
| 11584 | |
| 11585 | @item Waiting on entry call |
| 11586 | The task is waiting on an entry call. |
| 11587 | |
| 11588 | @item Async Select Wait |
| 11589 | The task is waiting to start the abortable part of an asynchronous |
| 11590 | select statement. |
| 11591 | |
| 11592 | @item Delay Sleep |
| 11593 | The task is waiting on a select statement with only a delay |
| 11594 | alternative open. |
| 11595 | |
| 11596 | @item Child Termination Wait |
| 11597 | The task is sleeping having completed a master within itself, and is |
| 11598 | waiting for the tasks dependent on that master to become terminated or |
| 11599 | waiting on a terminate Phase. |
| 11600 | |
| 11601 | @item Wait Child in Term Alt |
| 11602 | The task is sleeping waiting for tasks on terminate alternatives to |
| 11603 | finish terminating. |
| 11604 | |
| 11605 | @item Accepting RV with @var{taskno} |
| 11606 | The task is accepting a rendez-vous with the task @var{taskno}. |
| 11607 | @end table |
| 11608 | |
| 11609 | @item Name |
| 11610 | Name of the task in the program. |
| 11611 | |
| 11612 | @end table |
| 11613 | |
| 11614 | @kindex info task @var{taskno} |
| 11615 | @item info task @var{taskno} |
| 11616 | This command shows detailled informations on the specified task, as in |
| 11617 | the following example: |
| 11618 | @smallexample |
| 11619 | @iftex |
| 11620 | @leftskip=0.5cm |
| 11621 | @end iftex |
| 11622 | (@value{GDBP}) info tasks |
| 11623 | ID TID P-ID Pri State Name |
| 11624 | 1 8077880 0 15 Child Activation Wait main_task |
| 11625 | * 2 807c468 1 15 Running task_1 |
| 11626 | (@value{GDBP}) info task 2 |
| 11627 | Ada Task: 0x807c468 |
| 11628 | Name: task_1 |
| 11629 | Thread: 0x807f378 |
| 11630 | Parent: 1 (main_task) |
| 11631 | Base Priority: 15 |
| 11632 | State: Runnable |
| 11633 | @end smallexample |
| 11634 | |
| 11635 | @item task |
| 11636 | @kindex task@r{ (Ada)} |
| 11637 | @cindex current Ada task ID |
| 11638 | This command prints the ID of the current task. |
| 11639 | |
| 11640 | @smallexample |
| 11641 | @iftex |
| 11642 | @leftskip=0.5cm |
| 11643 | @end iftex |
| 11644 | (@value{GDBP}) info tasks |
| 11645 | ID TID P-ID Pri State Name |
| 11646 | 1 8077870 0 15 Child Activation Wait main_task |
| 11647 | * 2 807c458 1 15 Running t |
| 11648 | (@value{GDBP}) task |
| 11649 | [Current task is 2] |
| 11650 | @end smallexample |
| 11651 | |
| 11652 | @item task @var{taskno} |
| 11653 | @cindex Ada task switching |
| 11654 | This command is like the @code{thread @var{threadno}} |
| 11655 | command (@pxref{Threads}). It switches the context of debugging |
| 11656 | from the current task to the given task. |
| 11657 | |
| 11658 | @smallexample |
| 11659 | @iftex |
| 11660 | @leftskip=0.5cm |
| 11661 | @end iftex |
| 11662 | (@value{GDBP}) info tasks |
| 11663 | ID TID P-ID Pri State Name |
| 11664 | 1 8077870 0 15 Child Activation Wait main_task |
| 11665 | * 2 807c458 1 15 Running t |
| 11666 | (@value{GDBP}) task 1 |
| 11667 | [Switching to task 1] |
| 11668 | #0 0x8067726 in pthread_cond_wait () |
| 11669 | (@value{GDBP}) bt |
| 11670 | #0 0x8067726 in pthread_cond_wait () |
| 11671 | #1 0x8056714 in system.os_interface.pthread_cond_wait () |
| 11672 | #2 0x805cb63 in system.task_primitives.operations.sleep () |
| 11673 | #3 0x806153e in system.tasking.stages.activate_tasks () |
| 11674 | #4 0x804aacc in un () at un.adb:5 |
| 11675 | @end smallexample |
| 11676 | |
| 11677 | @end table |
| 11678 | |
| 11679 | @node Ada Tasks and Core Files |
| 11680 | @subsubsection Tasking Support when Debugging Core Files |
| 11681 | @cindex Ada tasking and core file debugging |
| 11682 | |
| 11683 | When inspecting a core file, as opposed to debugging a live program, |
| 11684 | tasking support may be limited or even unavailable, depending on |
| 11685 | the platform being used. |
| 11686 | For instance, on x86-linux, the list of tasks is available, but task |
| 11687 | switching is not supported. On Tru64, however, task switching will work |
| 11688 | as usual. |
| 11689 | |
| 11690 | On certain platforms, including Tru64, the debugger needs to perform some |
| 11691 | memory writes in order to provide Ada tasking support. When inspecting |
| 11692 | a core file, this means that the core file must be opened with read-write |
| 11693 | privileges, using the command @samp{"set write on"} (@pxref{Patching}). |
| 11694 | Under these circumstances, you should make a backup copy of the core |
| 11695 | file before inspecting it with @value{GDBN}. |
| 11696 | |
| 11697 | @node Ada Glitches |
| 11698 | @subsubsection Known Peculiarities of Ada Mode |
| 11699 | @cindex Ada, problems |
| 11700 | |
| 11701 | Besides the omissions listed previously (@pxref{Omissions from Ada}), |
| 11702 | we know of several problems with and limitations of Ada mode in |
| 11703 | @value{GDBN}, |
| 11704 | some of which will be fixed with planned future releases of the debugger |
| 11705 | and the GNU Ada compiler. |
| 11706 | |
| 11707 | @itemize @bullet |
| 11708 | @item |
| 11709 | Currently, the debugger |
| 11710 | has insufficient information to determine whether certain pointers represent |
| 11711 | pointers to objects or the objects themselves. |
| 11712 | Thus, the user may have to tack an extra @code{.all} after an expression |
| 11713 | to get it printed properly. |
| 11714 | |
| 11715 | @item |
| 11716 | Static constants that the compiler chooses not to materialize as objects in |
| 11717 | storage are invisible to the debugger. |
| 11718 | |
| 11719 | @item |
| 11720 | Named parameter associations in function argument lists are ignored (the |
| 11721 | argument lists are treated as positional). |
| 11722 | |
| 11723 | @item |
| 11724 | Many useful library packages are currently invisible to the debugger. |
| 11725 | |
| 11726 | @item |
| 11727 | Fixed-point arithmetic, conversions, input, and output is carried out using |
| 11728 | floating-point arithmetic, and may give results that only approximate those on |
| 11729 | the host machine. |
| 11730 | |
| 11731 | @item |
| 11732 | The GNAT compiler never generates the prefix @code{Standard} for any of |
| 11733 | the standard symbols defined by the Ada language. @value{GDBN} knows about |
| 11734 | this: it will strip the prefix from names when you use it, and will never |
| 11735 | look for a name you have so qualified among local symbols, nor match against |
| 11736 | symbols in other packages or subprograms. If you have |
| 11737 | defined entities anywhere in your program other than parameters and |
| 11738 | local variables whose simple names match names in @code{Standard}, |
| 11739 | GNAT's lack of qualification here can cause confusion. When this happens, |
| 11740 | you can usually resolve the confusion |
| 11741 | by qualifying the problematic names with package |
| 11742 | @code{Standard} explicitly. |
| 11743 | @end itemize |
| 11744 | |
| 11745 | @node Unsupported Languages |
| 11746 | @section Unsupported Languages |
| 11747 | |
| 11748 | @cindex unsupported languages |
| 11749 | @cindex minimal language |
| 11750 | In addition to the other fully-supported programming languages, |
| 11751 | @value{GDBN} also provides a pseudo-language, called @code{minimal}. |
| 11752 | It does not represent a real programming language, but provides a set |
| 11753 | of capabilities close to what the C or assembly languages provide. |
| 11754 | This should allow most simple operations to be performed while debugging |
| 11755 | an application that uses a language currently not supported by @value{GDBN}. |
| 11756 | |
| 11757 | If the language is set to @code{auto}, @value{GDBN} will automatically |
| 11758 | select this language if the current frame corresponds to an unsupported |
| 11759 | language. |
| 11760 | |
| 11761 | @node Symbols |
| 11762 | @chapter Examining the Symbol Table |
| 11763 | |
| 11764 | The commands described in this chapter allow you to inquire about the |
| 11765 | symbols (names of variables, functions and types) defined in your |
| 11766 | program. This information is inherent in the text of your program and |
| 11767 | does not change as your program executes. @value{GDBN} finds it in your |
| 11768 | program's symbol table, in the file indicated when you started @value{GDBN} |
| 11769 | (@pxref{File Options, ,Choosing Files}), or by one of the |
| 11770 | file-management commands (@pxref{Files, ,Commands to Specify Files}). |
| 11771 | |
| 11772 | @cindex symbol names |
| 11773 | @cindex names of symbols |
| 11774 | @cindex quoting names |
| 11775 | Occasionally, you may need to refer to symbols that contain unusual |
| 11776 | characters, which @value{GDBN} ordinarily treats as word delimiters. The |
| 11777 | most frequent case is in referring to static variables in other |
| 11778 | source files (@pxref{Variables,,Program Variables}). File names |
| 11779 | are recorded in object files as debugging symbols, but @value{GDBN} would |
| 11780 | ordinarily parse a typical file name, like @file{foo.c}, as the three words |
| 11781 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize |
| 11782 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, |
| 11783 | |
| 11784 | @smallexample |
| 11785 | p 'foo.c'::x |
| 11786 | @end smallexample |
| 11787 | |
| 11788 | @noindent |
| 11789 | looks up the value of @code{x} in the scope of the file @file{foo.c}. |
| 11790 | |
| 11791 | @table @code |
| 11792 | @cindex case-insensitive symbol names |
| 11793 | @cindex case sensitivity in symbol names |
| 11794 | @kindex set case-sensitive |
| 11795 | @item set case-sensitive on |
| 11796 | @itemx set case-sensitive off |
| 11797 | @itemx set case-sensitive auto |
| 11798 | Normally, when @value{GDBN} looks up symbols, it matches their names |
| 11799 | with case sensitivity determined by the current source language. |
| 11800 | Occasionally, you may wish to control that. The command @code{set |
| 11801 | case-sensitive} lets you do that by specifying @code{on} for |
| 11802 | case-sensitive matches or @code{off} for case-insensitive ones. If |
| 11803 | you specify @code{auto}, case sensitivity is reset to the default |
| 11804 | suitable for the source language. The default is case-sensitive |
| 11805 | matches for all languages except for Fortran, for which the default is |
| 11806 | case-insensitive matches. |
| 11807 | |
| 11808 | @kindex show case-sensitive |
| 11809 | @item show case-sensitive |
| 11810 | This command shows the current setting of case sensitivity for symbols |
| 11811 | lookups. |
| 11812 | |
| 11813 | @kindex info address |
| 11814 | @cindex address of a symbol |
| 11815 | @item info address @var{symbol} |
| 11816 | Describe where the data for @var{symbol} is stored. For a register |
| 11817 | variable, this says which register it is kept in. For a non-register |
| 11818 | local variable, this prints the stack-frame offset at which the variable |
| 11819 | is always stored. |
| 11820 | |
| 11821 | Note the contrast with @samp{print &@var{symbol}}, which does not work |
| 11822 | at all for a register variable, and for a stack local variable prints |
| 11823 | the exact address of the current instantiation of the variable. |
| 11824 | |
| 11825 | @kindex info symbol |
| 11826 | @cindex symbol from address |
| 11827 | @cindex closest symbol and offset for an address |
| 11828 | @item info symbol @var{addr} |
| 11829 | Print the name of a symbol which is stored at the address @var{addr}. |
| 11830 | If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the |
| 11831 | nearest symbol and an offset from it: |
| 11832 | |
| 11833 | @smallexample |
| 11834 | (@value{GDBP}) info symbol 0x54320 |
| 11835 | _initialize_vx + 396 in section .text |
| 11836 | @end smallexample |
| 11837 | |
| 11838 | @noindent |
| 11839 | This is the opposite of the @code{info address} command. You can use |
| 11840 | it to find out the name of a variable or a function given its address. |
| 11841 | |
| 11842 | For dynamically linked executables, the name of executable or shared |
| 11843 | library containing the symbol is also printed: |
| 11844 | |
| 11845 | @smallexample |
| 11846 | (@value{GDBP}) info symbol 0x400225 |
| 11847 | _start + 5 in section .text of /tmp/a.out |
| 11848 | (@value{GDBP}) info symbol 0x2aaaac2811cf |
| 11849 | __read_nocancel + 6 in section .text of /usr/lib64/libc.so.6 |
| 11850 | @end smallexample |
| 11851 | |
| 11852 | @kindex whatis |
| 11853 | @item whatis [@var{arg}] |
| 11854 | Print the data type of @var{arg}, which can be either an expression or |
| 11855 | a data type. With no argument, print the data type of @code{$}, the |
| 11856 | last value in the value history. If @var{arg} is an expression, it is |
| 11857 | not actually evaluated, and any side-effecting operations (such as |
| 11858 | assignments or function calls) inside it do not take place. If |
| 11859 | @var{arg} is a type name, it may be the name of a type or typedef, or |
| 11860 | for C code it may have the form @samp{class @var{class-name}}, |
| 11861 | @samp{struct @var{struct-tag}}, @samp{union @var{union-tag}} or |
| 11862 | @samp{enum @var{enum-tag}}. |
| 11863 | @xref{Expressions, ,Expressions}. |
| 11864 | |
| 11865 | @kindex ptype |
| 11866 | @item ptype [@var{arg}] |
| 11867 | @code{ptype} accepts the same arguments as @code{whatis}, but prints a |
| 11868 | detailed description of the type, instead of just the name of the type. |
| 11869 | @xref{Expressions, ,Expressions}. |
| 11870 | |
| 11871 | For example, for this variable declaration: |
| 11872 | |
| 11873 | @smallexample |
| 11874 | struct complex @{double real; double imag;@} v; |
| 11875 | @end smallexample |
| 11876 | |
| 11877 | @noindent |
| 11878 | the two commands give this output: |
| 11879 | |
| 11880 | @smallexample |
| 11881 | @group |
| 11882 | (@value{GDBP}) whatis v |
| 11883 | type = struct complex |
| 11884 | (@value{GDBP}) ptype v |
| 11885 | type = struct complex @{ |
| 11886 | double real; |
| 11887 | double imag; |
| 11888 | @} |
| 11889 | @end group |
| 11890 | @end smallexample |
| 11891 | |
| 11892 | @noindent |
| 11893 | As with @code{whatis}, using @code{ptype} without an argument refers to |
| 11894 | the type of @code{$}, the last value in the value history. |
| 11895 | |
| 11896 | @cindex incomplete type |
| 11897 | Sometimes, programs use opaque data types or incomplete specifications |
| 11898 | of complex data structure. If the debug information included in the |
| 11899 | program does not allow @value{GDBN} to display a full declaration of |
| 11900 | the data type, it will say @samp{<incomplete type>}. For example, |
| 11901 | given these declarations: |
| 11902 | |
| 11903 | @smallexample |
| 11904 | struct foo; |
| 11905 | struct foo *fooptr; |
| 11906 | @end smallexample |
| 11907 | |
| 11908 | @noindent |
| 11909 | but no definition for @code{struct foo} itself, @value{GDBN} will say: |
| 11910 | |
| 11911 | @smallexample |
| 11912 | (@value{GDBP}) ptype foo |
| 11913 | $1 = <incomplete type> |
| 11914 | @end smallexample |
| 11915 | |
| 11916 | @noindent |
| 11917 | ``Incomplete type'' is C terminology for data types that are not |
| 11918 | completely specified. |
| 11919 | |
| 11920 | @kindex info types |
| 11921 | @item info types @var{regexp} |
| 11922 | @itemx info types |
| 11923 | Print a brief description of all types whose names match the regular |
| 11924 | expression @var{regexp} (or all types in your program, if you supply |
| 11925 | no argument). Each complete typename is matched as though it were a |
| 11926 | complete line; thus, @samp{i type value} gives information on all |
| 11927 | types in your program whose names include the string @code{value}, but |
| 11928 | @samp{i type ^value$} gives information only on types whose complete |
| 11929 | name is @code{value}. |
| 11930 | |
| 11931 | This command differs from @code{ptype} in two ways: first, like |
| 11932 | @code{whatis}, it does not print a detailed description; second, it |
| 11933 | lists all source files where a type is defined. |
| 11934 | |
| 11935 | @kindex info scope |
| 11936 | @cindex local variables |
| 11937 | @item info scope @var{location} |
| 11938 | List all the variables local to a particular scope. This command |
| 11939 | accepts a @var{location} argument---a function name, a source line, or |
| 11940 | an address preceded by a @samp{*}, and prints all the variables local |
| 11941 | to the scope defined by that location. (@xref{Specify Location}, for |
| 11942 | details about supported forms of @var{location}.) For example: |
| 11943 | |
| 11944 | @smallexample |
| 11945 | (@value{GDBP}) @b{info scope command_line_handler} |
| 11946 | Scope for command_line_handler: |
| 11947 | Symbol rl is an argument at stack/frame offset 8, length 4. |
| 11948 | Symbol linebuffer is in static storage at address 0x150a18, length 4. |
| 11949 | Symbol linelength is in static storage at address 0x150a1c, length 4. |
| 11950 | Symbol p is a local variable in register $esi, length 4. |
| 11951 | Symbol p1 is a local variable in register $ebx, length 4. |
| 11952 | Symbol nline is a local variable in register $edx, length 4. |
| 11953 | Symbol repeat is a local variable at frame offset -8, length 4. |
| 11954 | @end smallexample |
| 11955 | |
| 11956 | @noindent |
| 11957 | This command is especially useful for determining what data to collect |
| 11958 | during a @dfn{trace experiment}, see @ref{Tracepoint Actions, |
| 11959 | collect}. |
| 11960 | |
| 11961 | @kindex info source |
| 11962 | @item info source |
| 11963 | Show information about the current source file---that is, the source file for |
| 11964 | the function containing the current point of execution: |
| 11965 | @itemize @bullet |
| 11966 | @item |
| 11967 | the name of the source file, and the directory containing it, |
| 11968 | @item |
| 11969 | the directory it was compiled in, |
| 11970 | @item |
| 11971 | its length, in lines, |
| 11972 | @item |
| 11973 | which programming language it is written in, |
| 11974 | @item |
| 11975 | whether the executable includes debugging information for that file, and |
| 11976 | if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and |
| 11977 | @item |
| 11978 | whether the debugging information includes information about |
| 11979 | preprocessor macros. |
| 11980 | @end itemize |
| 11981 | |
| 11982 | |
| 11983 | @kindex info sources |
| 11984 | @item info sources |
| 11985 | Print the names of all source files in your program for which there is |
| 11986 | debugging information, organized into two lists: files whose symbols |
| 11987 | have already been read, and files whose symbols will be read when needed. |
| 11988 | |
| 11989 | @kindex info functions |
| 11990 | @item info functions |
| 11991 | Print the names and data types of all defined functions. |
| 11992 | |
| 11993 | @item info functions @var{regexp} |
| 11994 | Print the names and data types of all defined functions |
| 11995 | whose names contain a match for regular expression @var{regexp}. |
| 11996 | Thus, @samp{info fun step} finds all functions whose names |
| 11997 | include @code{step}; @samp{info fun ^step} finds those whose names |
| 11998 | start with @code{step}. If a function name contains characters |
| 11999 | that conflict with the regular expression language (e.g.@: |
| 12000 | @samp{operator*()}), they may be quoted with a backslash. |
| 12001 | |
| 12002 | @kindex info variables |
| 12003 | @item info variables |
| 12004 | Print the names and data types of all variables that are declared |
| 12005 | outside of functions (i.e.@: excluding local variables). |
| 12006 | |
| 12007 | @item info variables @var{regexp} |
| 12008 | Print the names and data types of all variables (except for local |
| 12009 | variables) whose names contain a match for regular expression |
| 12010 | @var{regexp}. |
| 12011 | |
| 12012 | @kindex info classes |
| 12013 | @cindex Objective-C, classes and selectors |
| 12014 | @item info classes |
| 12015 | @itemx info classes @var{regexp} |
| 12016 | Display all Objective-C classes in your program, or |
| 12017 | (with the @var{regexp} argument) all those matching a particular regular |
| 12018 | expression. |
| 12019 | |
| 12020 | @kindex info selectors |
| 12021 | @item info selectors |
| 12022 | @itemx info selectors @var{regexp} |
| 12023 | Display all Objective-C selectors in your program, or |
| 12024 | (with the @var{regexp} argument) all those matching a particular regular |
| 12025 | expression. |
| 12026 | |
| 12027 | @ignore |
| 12028 | This was never implemented. |
| 12029 | @kindex info methods |
| 12030 | @item info methods |
| 12031 | @itemx info methods @var{regexp} |
| 12032 | The @code{info methods} command permits the user to examine all defined |
| 12033 | methods within C@t{++} program, or (with the @var{regexp} argument) a |
| 12034 | specific set of methods found in the various C@t{++} classes. Many |
| 12035 | C@t{++} classes provide a large number of methods. Thus, the output |
| 12036 | from the @code{ptype} command can be overwhelming and hard to use. The |
| 12037 | @code{info-methods} command filters the methods, printing only those |
| 12038 | which match the regular-expression @var{regexp}. |
| 12039 | @end ignore |
| 12040 | |
| 12041 | @cindex reloading symbols |
| 12042 | Some systems allow individual object files that make up your program to |
| 12043 | be replaced without stopping and restarting your program. For example, |
| 12044 | in VxWorks you can simply recompile a defective object file and keep on |
| 12045 | running. If you are running on one of these systems, you can allow |
| 12046 | @value{GDBN} to reload the symbols for automatically relinked modules: |
| 12047 | |
| 12048 | @table @code |
| 12049 | @kindex set symbol-reloading |
| 12050 | @item set symbol-reloading on |
| 12051 | Replace symbol definitions for the corresponding source file when an |
| 12052 | object file with a particular name is seen again. |
| 12053 | |
| 12054 | @item set symbol-reloading off |
| 12055 | Do not replace symbol definitions when encountering object files of the |
| 12056 | same name more than once. This is the default state; if you are not |
| 12057 | running on a system that permits automatic relinking of modules, you |
| 12058 | should leave @code{symbol-reloading} off, since otherwise @value{GDBN} |
| 12059 | may discard symbols when linking large programs, that may contain |
| 12060 | several modules (from different directories or libraries) with the same |
| 12061 | name. |
| 12062 | |
| 12063 | @kindex show symbol-reloading |
| 12064 | @item show symbol-reloading |
| 12065 | Show the current @code{on} or @code{off} setting. |
| 12066 | @end table |
| 12067 | |
| 12068 | @cindex opaque data types |
| 12069 | @kindex set opaque-type-resolution |
| 12070 | @item set opaque-type-resolution on |
| 12071 | Tell @value{GDBN} to resolve opaque types. An opaque type is a type |
| 12072 | declared as a pointer to a @code{struct}, @code{class}, or |
| 12073 | @code{union}---for example, @code{struct MyType *}---that is used in one |
| 12074 | source file although the full declaration of @code{struct MyType} is in |
| 12075 | another source file. The default is on. |
| 12076 | |
| 12077 | A change in the setting of this subcommand will not take effect until |
| 12078 | the next time symbols for a file are loaded. |
| 12079 | |
| 12080 | @item set opaque-type-resolution off |
| 12081 | Tell @value{GDBN} not to resolve opaque types. In this case, the type |
| 12082 | is printed as follows: |
| 12083 | @smallexample |
| 12084 | @{<no data fields>@} |
| 12085 | @end smallexample |
| 12086 | |
| 12087 | @kindex show opaque-type-resolution |
| 12088 | @item show opaque-type-resolution |
| 12089 | Show whether opaque types are resolved or not. |
| 12090 | |
| 12091 | @kindex set print symbol-loading |
| 12092 | @cindex print messages when symbols are loaded |
| 12093 | @item set print symbol-loading |
| 12094 | @itemx set print symbol-loading on |
| 12095 | @itemx set print symbol-loading off |
| 12096 | The @code{set print symbol-loading} command allows you to enable or |
| 12097 | disable printing of messages when @value{GDBN} loads symbols. |
| 12098 | By default, these messages will be printed, and normally this is what |
| 12099 | you want. Disabling these messages is useful when debugging applications |
| 12100 | with lots of shared libraries where the quantity of output can be more |
| 12101 | annoying than useful. |
| 12102 | |
| 12103 | @kindex show print symbol-loading |
| 12104 | @item show print symbol-loading |
| 12105 | Show whether messages will be printed when @value{GDBN} loads symbols. |
| 12106 | |
| 12107 | @kindex maint print symbols |
| 12108 | @cindex symbol dump |
| 12109 | @kindex maint print psymbols |
| 12110 | @cindex partial symbol dump |
| 12111 | @item maint print symbols @var{filename} |
| 12112 | @itemx maint print psymbols @var{filename} |
| 12113 | @itemx maint print msymbols @var{filename} |
| 12114 | Write a dump of debugging symbol data into the file @var{filename}. |
| 12115 | These commands are used to debug the @value{GDBN} symbol-reading code. Only |
| 12116 | symbols with debugging data are included. If you use @samp{maint print |
| 12117 | symbols}, @value{GDBN} includes all the symbols for which it has already |
| 12118 | collected full details: that is, @var{filename} reflects symbols for |
| 12119 | only those files whose symbols @value{GDBN} has read. You can use the |
| 12120 | command @code{info sources} to find out which files these are. If you |
| 12121 | use @samp{maint print psymbols} instead, the dump shows information about |
| 12122 | symbols that @value{GDBN} only knows partially---that is, symbols defined in |
| 12123 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, |
| 12124 | @samp{maint print msymbols} dumps just the minimal symbol information |
| 12125 | required for each object file from which @value{GDBN} has read some symbols. |
| 12126 | @xref{Files, ,Commands to Specify Files}, for a discussion of how |
| 12127 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). |
| 12128 | |
| 12129 | @kindex maint info symtabs |
| 12130 | @kindex maint info psymtabs |
| 12131 | @cindex listing @value{GDBN}'s internal symbol tables |
| 12132 | @cindex symbol tables, listing @value{GDBN}'s internal |
| 12133 | @cindex full symbol tables, listing @value{GDBN}'s internal |
| 12134 | @cindex partial symbol tables, listing @value{GDBN}'s internal |
| 12135 | @item maint info symtabs @r{[} @var{regexp} @r{]} |
| 12136 | @itemx maint info psymtabs @r{[} @var{regexp} @r{]} |
| 12137 | |
| 12138 | List the @code{struct symtab} or @code{struct partial_symtab} |
| 12139 | structures whose names match @var{regexp}. If @var{regexp} is not |
| 12140 | given, list them all. The output includes expressions which you can |
| 12141 | copy into a @value{GDBN} debugging this one to examine a particular |
| 12142 | structure in more detail. For example: |
| 12143 | |
| 12144 | @smallexample |
| 12145 | (@value{GDBP}) maint info psymtabs dwarf2read |
| 12146 | @{ objfile /home/gnu/build/gdb/gdb |
| 12147 | ((struct objfile *) 0x82e69d0) |
| 12148 | @{ psymtab /home/gnu/src/gdb/dwarf2read.c |
| 12149 | ((struct partial_symtab *) 0x8474b10) |
| 12150 | readin no |
| 12151 | fullname (null) |
| 12152 | text addresses 0x814d3c8 -- 0x8158074 |
| 12153 | globals (* (struct partial_symbol **) 0x8507a08 @@ 9) |
| 12154 | statics (* (struct partial_symbol **) 0x40e95b78 @@ 2882) |
| 12155 | dependencies (none) |
| 12156 | @} |
| 12157 | @} |
| 12158 | (@value{GDBP}) maint info symtabs |
| 12159 | (@value{GDBP}) |
| 12160 | @end smallexample |
| 12161 | @noindent |
| 12162 | We see that there is one partial symbol table whose filename contains |
| 12163 | the string @samp{dwarf2read}, belonging to the @samp{gdb} executable; |
| 12164 | and we see that @value{GDBN} has not read in any symtabs yet at all. |
| 12165 | If we set a breakpoint on a function, that will cause @value{GDBN} to |
| 12166 | read the symtab for the compilation unit containing that function: |
| 12167 | |
| 12168 | @smallexample |
| 12169 | (@value{GDBP}) break dwarf2_psymtab_to_symtab |
| 12170 | Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c, |
| 12171 | line 1574. |
| 12172 | (@value{GDBP}) maint info symtabs |
| 12173 | @{ objfile /home/gnu/build/gdb/gdb |
| 12174 | ((struct objfile *) 0x82e69d0) |
| 12175 | @{ symtab /home/gnu/src/gdb/dwarf2read.c |
| 12176 | ((struct symtab *) 0x86c1f38) |
| 12177 | dirname (null) |
| 12178 | fullname (null) |
| 12179 | blockvector ((struct blockvector *) 0x86c1bd0) (primary) |
| 12180 | linetable ((struct linetable *) 0x8370fa0) |
| 12181 | debugformat DWARF 2 |
| 12182 | @} |
| 12183 | @} |
| 12184 | (@value{GDBP}) |
| 12185 | @end smallexample |
| 12186 | @end table |
| 12187 | |
| 12188 | |
| 12189 | @node Altering |
| 12190 | @chapter Altering Execution |
| 12191 | |
| 12192 | Once you think you have found an error in your program, you might want to |
| 12193 | find out for certain whether correcting the apparent error would lead to |
| 12194 | correct results in the rest of the run. You can find the answer by |
| 12195 | experiment, using the @value{GDBN} features for altering execution of the |
| 12196 | program. |
| 12197 | |
| 12198 | For example, you can store new values into variables or memory |
| 12199 | locations, give your program a signal, restart it at a different |
| 12200 | address, or even return prematurely from a function. |
| 12201 | |
| 12202 | @menu |
| 12203 | * Assignment:: Assignment to variables |
| 12204 | * Jumping:: Continuing at a different address |
| 12205 | * Signaling:: Giving your program a signal |
| 12206 | * Returning:: Returning from a function |
| 12207 | * Calling:: Calling your program's functions |
| 12208 | * Patching:: Patching your program |
| 12209 | @end menu |
| 12210 | |
| 12211 | @node Assignment |
| 12212 | @section Assignment to Variables |
| 12213 | |
| 12214 | @cindex assignment |
| 12215 | @cindex setting variables |
| 12216 | To alter the value of a variable, evaluate an assignment expression. |
| 12217 | @xref{Expressions, ,Expressions}. For example, |
| 12218 | |
| 12219 | @smallexample |
| 12220 | print x=4 |
| 12221 | @end smallexample |
| 12222 | |
| 12223 | @noindent |
| 12224 | stores the value 4 into the variable @code{x}, and then prints the |
| 12225 | value of the assignment expression (which is 4). |
| 12226 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more |
| 12227 | information on operators in supported languages. |
| 12228 | |
| 12229 | @kindex set variable |
| 12230 | @cindex variables, setting |
| 12231 | If you are not interested in seeing the value of the assignment, use the |
| 12232 | @code{set} command instead of the @code{print} command. @code{set} is |
| 12233 | really the same as @code{print} except that the expression's value is |
| 12234 | not printed and is not put in the value history (@pxref{Value History, |
| 12235 | ,Value History}). The expression is evaluated only for its effects. |
| 12236 | |
| 12237 | If the beginning of the argument string of the @code{set} command |
| 12238 | appears identical to a @code{set} subcommand, use the @code{set |
| 12239 | variable} command instead of just @code{set}. This command is identical |
| 12240 | to @code{set} except for its lack of subcommands. For example, if your |
| 12241 | program has a variable @code{width}, you get an error if you try to set |
| 12242 | a new value with just @samp{set width=13}, because @value{GDBN} has the |
| 12243 | command @code{set width}: |
| 12244 | |
| 12245 | @smallexample |
| 12246 | (@value{GDBP}) whatis width |
| 12247 | type = double |
| 12248 | (@value{GDBP}) p width |
| 12249 | $4 = 13 |
| 12250 | (@value{GDBP}) set width=47 |
| 12251 | Invalid syntax in expression. |
| 12252 | @end smallexample |
| 12253 | |
| 12254 | @noindent |
| 12255 | The invalid expression, of course, is @samp{=47}. In |
| 12256 | order to actually set the program's variable @code{width}, use |
| 12257 | |
| 12258 | @smallexample |
| 12259 | (@value{GDBP}) set var width=47 |
| 12260 | @end smallexample |
| 12261 | |
| 12262 | Because the @code{set} command has many subcommands that can conflict |
| 12263 | with the names of program variables, it is a good idea to use the |
| 12264 | @code{set variable} command instead of just @code{set}. For example, if |
| 12265 | your program has a variable @code{g}, you run into problems if you try |
| 12266 | to set a new value with just @samp{set g=4}, because @value{GDBN} has |
| 12267 | the command @code{set gnutarget}, abbreviated @code{set g}: |
| 12268 | |
| 12269 | @smallexample |
| 12270 | @group |
| 12271 | (@value{GDBP}) whatis g |
| 12272 | type = double |
| 12273 | (@value{GDBP}) p g |
| 12274 | $1 = 1 |
| 12275 | (@value{GDBP}) set g=4 |
| 12276 | (@value{GDBP}) p g |
| 12277 | $2 = 1 |
| 12278 | (@value{GDBP}) r |
| 12279 | The program being debugged has been started already. |
| 12280 | Start it from the beginning? (y or n) y |
| 12281 | Starting program: /home/smith/cc_progs/a.out |
| 12282 | "/home/smith/cc_progs/a.out": can't open to read symbols: |
| 12283 | Invalid bfd target. |
| 12284 | (@value{GDBP}) show g |
| 12285 | The current BFD target is "=4". |
| 12286 | @end group |
| 12287 | @end smallexample |
| 12288 | |
| 12289 | @noindent |
| 12290 | The program variable @code{g} did not change, and you silently set the |
| 12291 | @code{gnutarget} to an invalid value. In order to set the variable |
| 12292 | @code{g}, use |
| 12293 | |
| 12294 | @smallexample |
| 12295 | (@value{GDBP}) set var g=4 |
| 12296 | @end smallexample |
| 12297 | |
| 12298 | @value{GDBN} allows more implicit conversions in assignments than C; you can |
| 12299 | freely store an integer value into a pointer variable or vice versa, |
| 12300 | and you can convert any structure to any other structure that is the |
| 12301 | same length or shorter. |
| 12302 | @comment FIXME: how do structs align/pad in these conversions? |
| 12303 | @comment /doc@cygnus.com 18dec1990 |
| 12304 | |
| 12305 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} |
| 12306 | construct to generate a value of specified type at a specified address |
| 12307 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers |
| 12308 | to memory location @code{0x83040} as an integer (which implies a certain size |
| 12309 | and representation in memory), and |
| 12310 | |
| 12311 | @smallexample |
| 12312 | set @{int@}0x83040 = 4 |
| 12313 | @end smallexample |
| 12314 | |
| 12315 | @noindent |
| 12316 | stores the value 4 into that memory location. |
| 12317 | |
| 12318 | @node Jumping |
| 12319 | @section Continuing at a Different Address |
| 12320 | |
| 12321 | Ordinarily, when you continue your program, you do so at the place where |
| 12322 | it stopped, with the @code{continue} command. You can instead continue at |
| 12323 | an address of your own choosing, with the following commands: |
| 12324 | |
| 12325 | @table @code |
| 12326 | @kindex jump |
| 12327 | @item jump @var{linespec} |
| 12328 | @itemx jump @var{location} |
| 12329 | Resume execution at line @var{linespec} or at address given by |
| 12330 | @var{location}. Execution stops again immediately if there is a |
| 12331 | breakpoint there. @xref{Specify Location}, for a description of the |
| 12332 | different forms of @var{linespec} and @var{location}. It is common |
| 12333 | practice to use the @code{tbreak} command in conjunction with |
| 12334 | @code{jump}. @xref{Set Breaks, ,Setting Breakpoints}. |
| 12335 | |
| 12336 | The @code{jump} command does not change the current stack frame, or |
| 12337 | the stack pointer, or the contents of any memory location or any |
| 12338 | register other than the program counter. If line @var{linespec} is in |
| 12339 | a different function from the one currently executing, the results may |
| 12340 | be bizarre if the two functions expect different patterns of arguments or |
| 12341 | of local variables. For this reason, the @code{jump} command requests |
| 12342 | confirmation if the specified line is not in the function currently |
| 12343 | executing. However, even bizarre results are predictable if you are |
| 12344 | well acquainted with the machine-language code of your program. |
| 12345 | @end table |
| 12346 | |
| 12347 | @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt. |
| 12348 | On many systems, you can get much the same effect as the @code{jump} |
| 12349 | command by storing a new value into the register @code{$pc}. The |
| 12350 | difference is that this does not start your program running; it only |
| 12351 | changes the address of where it @emph{will} run when you continue. For |
| 12352 | example, |
| 12353 | |
| 12354 | @smallexample |
| 12355 | set $pc = 0x485 |
| 12356 | @end smallexample |
| 12357 | |
| 12358 | @noindent |
| 12359 | makes the next @code{continue} command or stepping command execute at |
| 12360 | address @code{0x485}, rather than at the address where your program stopped. |
| 12361 | @xref{Continuing and Stepping, ,Continuing and Stepping}. |
| 12362 | |
| 12363 | The most common occasion to use the @code{jump} command is to back |
| 12364 | up---perhaps with more breakpoints set---over a portion of a program |
| 12365 | that has already executed, in order to examine its execution in more |
| 12366 | detail. |
| 12367 | |
| 12368 | @c @group |
| 12369 | @node Signaling |
| 12370 | @section Giving your Program a Signal |
| 12371 | @cindex deliver a signal to a program |
| 12372 | |
| 12373 | @table @code |
| 12374 | @kindex signal |
| 12375 | @item signal @var{signal} |
| 12376 | Resume execution where your program stopped, but immediately give it the |
| 12377 | signal @var{signal}. @var{signal} can be the name or the number of a |
| 12378 | signal. For example, on many systems @code{signal 2} and @code{signal |
| 12379 | SIGINT} are both ways of sending an interrupt signal. |
| 12380 | |
| 12381 | Alternatively, if @var{signal} is zero, continue execution without |
| 12382 | giving a signal. This is useful when your program stopped on account of |
| 12383 | a signal and would ordinary see the signal when resumed with the |
| 12384 | @code{continue} command; @samp{signal 0} causes it to resume without a |
| 12385 | signal. |
| 12386 | |
| 12387 | @code{signal} does not repeat when you press @key{RET} a second time |
| 12388 | after executing the command. |
| 12389 | @end table |
| 12390 | @c @end group |
| 12391 | |
| 12392 | Invoking the @code{signal} command is not the same as invoking the |
| 12393 | @code{kill} utility from the shell. Sending a signal with @code{kill} |
| 12394 | causes @value{GDBN} to decide what to do with the signal depending on |
| 12395 | the signal handling tables (@pxref{Signals}). The @code{signal} command |
| 12396 | passes the signal directly to your program. |
| 12397 | |
| 12398 | |
| 12399 | @node Returning |
| 12400 | @section Returning from a Function |
| 12401 | |
| 12402 | @table @code |
| 12403 | @cindex returning from a function |
| 12404 | @kindex return |
| 12405 | @item return |
| 12406 | @itemx return @var{expression} |
| 12407 | You can cancel execution of a function call with the @code{return} |
| 12408 | command. If you give an |
| 12409 | @var{expression} argument, its value is used as the function's return |
| 12410 | value. |
| 12411 | @end table |
| 12412 | |
| 12413 | When you use @code{return}, @value{GDBN} discards the selected stack frame |
| 12414 | (and all frames within it). You can think of this as making the |
| 12415 | discarded frame return prematurely. If you wish to specify a value to |
| 12416 | be returned, give that value as the argument to @code{return}. |
| 12417 | |
| 12418 | This pops the selected stack frame (@pxref{Selection, ,Selecting a |
| 12419 | Frame}), and any other frames inside of it, leaving its caller as the |
| 12420 | innermost remaining frame. That frame becomes selected. The |
| 12421 | specified value is stored in the registers used for returning values |
| 12422 | of functions. |
| 12423 | |
| 12424 | The @code{return} command does not resume execution; it leaves the |
| 12425 | program stopped in the state that would exist if the function had just |
| 12426 | returned. In contrast, the @code{finish} command (@pxref{Continuing |
| 12427 | and Stepping, ,Continuing and Stepping}) resumes execution until the |
| 12428 | selected stack frame returns naturally. |
| 12429 | |
| 12430 | @node Calling |
| 12431 | @section Calling Program Functions |
| 12432 | |
| 12433 | @table @code |
| 12434 | @cindex calling functions |
| 12435 | @cindex inferior functions, calling |
| 12436 | @item print @var{expr} |
| 12437 | Evaluate the expression @var{expr} and display the resulting value. |
| 12438 | @var{expr} may include calls to functions in the program being |
| 12439 | debugged. |
| 12440 | |
| 12441 | @kindex call |
| 12442 | @item call @var{expr} |
| 12443 | Evaluate the expression @var{expr} without displaying @code{void} |
| 12444 | returned values. |
| 12445 | |
| 12446 | You can use this variant of the @code{print} command if you want to |
| 12447 | execute a function from your program that does not return anything |
| 12448 | (a.k.a.@: @dfn{a void function}), but without cluttering the output |
| 12449 | with @code{void} returned values that @value{GDBN} will otherwise |
| 12450 | print. If the result is not void, it is printed and saved in the |
| 12451 | value history. |
| 12452 | @end table |
| 12453 | |
| 12454 | It is possible for the function you call via the @code{print} or |
| 12455 | @code{call} command to generate a signal (e.g., if there's a bug in |
| 12456 | the function, or if you passed it incorrect arguments). What happens |
| 12457 | in that case is controlled by the @code{set unwindonsignal} command. |
| 12458 | |
| 12459 | @table @code |
| 12460 | @item set unwindonsignal |
| 12461 | @kindex set unwindonsignal |
| 12462 | @cindex unwind stack in called functions |
| 12463 | @cindex call dummy stack unwinding |
| 12464 | Set unwinding of the stack if a signal is received while in a function |
| 12465 | that @value{GDBN} called in the program being debugged. If set to on, |
| 12466 | @value{GDBN} unwinds the stack it created for the call and restores |
| 12467 | the context to what it was before the call. If set to off (the |
| 12468 | default), @value{GDBN} stops in the frame where the signal was |
| 12469 | received. |
| 12470 | |
| 12471 | @item show unwindonsignal |
| 12472 | @kindex show unwindonsignal |
| 12473 | Show the current setting of stack unwinding in the functions called by |
| 12474 | @value{GDBN}. |
| 12475 | @end table |
| 12476 | |
| 12477 | @cindex weak alias functions |
| 12478 | Sometimes, a function you wish to call is actually a @dfn{weak alias} |
| 12479 | for another function. In such case, @value{GDBN} might not pick up |
| 12480 | the type information, including the types of the function arguments, |
| 12481 | which causes @value{GDBN} to call the inferior function incorrectly. |
| 12482 | As a result, the called function will function erroneously and may |
| 12483 | even crash. A solution to that is to use the name of the aliased |
| 12484 | function instead. |
| 12485 | |
| 12486 | @node Patching |
| 12487 | @section Patching Programs |
| 12488 | |
| 12489 | @cindex patching binaries |
| 12490 | @cindex writing into executables |
| 12491 | @cindex writing into corefiles |
| 12492 | |
| 12493 | By default, @value{GDBN} opens the file containing your program's |
| 12494 | executable code (or the corefile) read-only. This prevents accidental |
| 12495 | alterations to machine code; but it also prevents you from intentionally |
| 12496 | patching your program's binary. |
| 12497 | |
| 12498 | If you'd like to be able to patch the binary, you can specify that |
| 12499 | explicitly with the @code{set write} command. For example, you might |
| 12500 | want to turn on internal debugging flags, or even to make emergency |
| 12501 | repairs. |
| 12502 | |
| 12503 | @table @code |
| 12504 | @kindex set write |
| 12505 | @item set write on |
| 12506 | @itemx set write off |
| 12507 | If you specify @samp{set write on}, @value{GDBN} opens executable and |
| 12508 | core files for both reading and writing; if you specify @kbd{set write |
| 12509 | off} (the default), @value{GDBN} opens them read-only. |
| 12510 | |
| 12511 | If you have already loaded a file, you must load it again (using the |
| 12512 | @code{exec-file} or @code{core-file} command) after changing @code{set |
| 12513 | write}, for your new setting to take effect. |
| 12514 | |
| 12515 | @item show write |
| 12516 | @kindex show write |
| 12517 | Display whether executable files and core files are opened for writing |
| 12518 | as well as reading. |
| 12519 | @end table |
| 12520 | |
| 12521 | @node GDB Files |
| 12522 | @chapter @value{GDBN} Files |
| 12523 | |
| 12524 | @value{GDBN} needs to know the file name of the program to be debugged, |
| 12525 | both in order to read its symbol table and in order to start your |
| 12526 | program. To debug a core dump of a previous run, you must also tell |
| 12527 | @value{GDBN} the name of the core dump file. |
| 12528 | |
| 12529 | @menu |
| 12530 | * Files:: Commands to specify files |
| 12531 | * Separate Debug Files:: Debugging information in separate files |
| 12532 | * Symbol Errors:: Errors reading symbol files |
| 12533 | @end menu |
| 12534 | |
| 12535 | @node Files |
| 12536 | @section Commands to Specify Files |
| 12537 | |
| 12538 | @cindex symbol table |
| 12539 | @cindex core dump file |
| 12540 | |
| 12541 | You may want to specify executable and core dump file names. The usual |
| 12542 | way to do this is at start-up time, using the arguments to |
| 12543 | @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and |
| 12544 | Out of @value{GDBN}}). |
| 12545 | |
| 12546 | Occasionally it is necessary to change to a different file during a |
| 12547 | @value{GDBN} session. Or you may run @value{GDBN} and forget to |
| 12548 | specify a file you want to use. Or you are debugging a remote target |
| 12549 | via @code{gdbserver} (@pxref{Server, file, Using the @code{gdbserver} |
| 12550 | Program}). In these situations the @value{GDBN} commands to specify |
| 12551 | new files are useful. |
| 12552 | |
| 12553 | @table @code |
| 12554 | @cindex executable file |
| 12555 | @kindex file |
| 12556 | @item file @var{filename} |
| 12557 | Use @var{filename} as the program to be debugged. It is read for its |
| 12558 | symbols and for the contents of pure memory. It is also the program |
| 12559 | executed when you use the @code{run} command. If you do not specify a |
| 12560 | directory and the file is not found in the @value{GDBN} working directory, |
| 12561 | @value{GDBN} uses the environment variable @code{PATH} as a list of |
| 12562 | directories to search, just as the shell does when looking for a program |
| 12563 | to run. You can change the value of this variable, for both @value{GDBN} |
| 12564 | and your program, using the @code{path} command. |
| 12565 | |
| 12566 | @cindex unlinked object files |
| 12567 | @cindex patching object files |
| 12568 | You can load unlinked object @file{.o} files into @value{GDBN} using |
| 12569 | the @code{file} command. You will not be able to ``run'' an object |
| 12570 | file, but you can disassemble functions and inspect variables. Also, |
| 12571 | if the underlying BFD functionality supports it, you could use |
| 12572 | @kbd{gdb -write} to patch object files using this technique. Note |
| 12573 | that @value{GDBN} can neither interpret nor modify relocations in this |
| 12574 | case, so branches and some initialized variables will appear to go to |
| 12575 | the wrong place. But this feature is still handy from time to time. |
| 12576 | |
| 12577 | @item file |
| 12578 | @code{file} with no argument makes @value{GDBN} discard any information it |
| 12579 | has on both executable file and the symbol table. |
| 12580 | |
| 12581 | @kindex exec-file |
| 12582 | @item exec-file @r{[} @var{filename} @r{]} |
| 12583 | Specify that the program to be run (but not the symbol table) is found |
| 12584 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} |
| 12585 | if necessary to locate your program. Omitting @var{filename} means to |
| 12586 | discard information on the executable file. |
| 12587 | |
| 12588 | @kindex symbol-file |
| 12589 | @item symbol-file @r{[} @var{filename} @r{]} |
| 12590 | Read symbol table information from file @var{filename}. @code{PATH} is |
| 12591 | searched when necessary. Use the @code{file} command to get both symbol |
| 12592 | table and program to run from the same file. |
| 12593 | |
| 12594 | @code{symbol-file} with no argument clears out @value{GDBN} information on your |
| 12595 | program's symbol table. |
| 12596 | |
| 12597 | The @code{symbol-file} command causes @value{GDBN} to forget the contents of |
| 12598 | some breakpoints and auto-display expressions. This is because they may |
| 12599 | contain pointers to the internal data recording symbols and data types, |
| 12600 | which are part of the old symbol table data being discarded inside |
| 12601 | @value{GDBN}. |
| 12602 | |
| 12603 | @code{symbol-file} does not repeat if you press @key{RET} again after |
| 12604 | executing it once. |
| 12605 | |
| 12606 | When @value{GDBN} is configured for a particular environment, it |
| 12607 | understands debugging information in whatever format is the standard |
| 12608 | generated for that environment; you may use either a @sc{gnu} compiler, or |
| 12609 | other compilers that adhere to the local conventions. |
| 12610 | Best results are usually obtained from @sc{gnu} compilers; for example, |
| 12611 | using @code{@value{NGCC}} you can generate debugging information for |
| 12612 | optimized code. |
| 12613 | |
| 12614 | For most kinds of object files, with the exception of old SVR3 systems |
| 12615 | using COFF, the @code{symbol-file} command does not normally read the |
| 12616 | symbol table in full right away. Instead, it scans the symbol table |
| 12617 | quickly to find which source files and which symbols are present. The |
| 12618 | details are read later, one source file at a time, as they are needed. |
| 12619 | |
| 12620 | The purpose of this two-stage reading strategy is to make @value{GDBN} |
| 12621 | start up faster. For the most part, it is invisible except for |
| 12622 | occasional pauses while the symbol table details for a particular source |
| 12623 | file are being read. (The @code{set verbose} command can turn these |
| 12624 | pauses into messages if desired. @xref{Messages/Warnings, ,Optional |
| 12625 | Warnings and Messages}.) |
| 12626 | |
| 12627 | We have not implemented the two-stage strategy for COFF yet. When the |
| 12628 | symbol table is stored in COFF format, @code{symbol-file} reads the |
| 12629 | symbol table data in full right away. Note that ``stabs-in-COFF'' |
| 12630 | still does the two-stage strategy, since the debug info is actually |
| 12631 | in stabs format. |
| 12632 | |
| 12633 | @kindex readnow |
| 12634 | @cindex reading symbols immediately |
| 12635 | @cindex symbols, reading immediately |
| 12636 | @item symbol-file @var{filename} @r{[} -readnow @r{]} |
| 12637 | @itemx file @var{filename} @r{[} -readnow @r{]} |
| 12638 | You can override the @value{GDBN} two-stage strategy for reading symbol |
| 12639 | tables by using the @samp{-readnow} option with any of the commands that |
| 12640 | load symbol table information, if you want to be sure @value{GDBN} has the |
| 12641 | entire symbol table available. |
| 12642 | |
| 12643 | @c FIXME: for now no mention of directories, since this seems to be in |
| 12644 | @c flux. 13mar1992 status is that in theory GDB would look either in |
| 12645 | @c current dir or in same dir as myprog; but issues like competing |
| 12646 | @c GDB's, or clutter in system dirs, mean that in practice right now |
| 12647 | @c only current dir is used. FFish says maybe a special GDB hierarchy |
| 12648 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol |
| 12649 | @c files. |
| 12650 | |
| 12651 | @kindex core-file |
| 12652 | @item core-file @r{[}@var{filename}@r{]} |
| 12653 | @itemx core |
| 12654 | Specify the whereabouts of a core dump file to be used as the ``contents |
| 12655 | of memory''. Traditionally, core files contain only some parts of the |
| 12656 | address space of the process that generated them; @value{GDBN} can access the |
| 12657 | executable file itself for other parts. |
| 12658 | |
| 12659 | @code{core-file} with no argument specifies that no core file is |
| 12660 | to be used. |
| 12661 | |
| 12662 | Note that the core file is ignored when your program is actually running |
| 12663 | under @value{GDBN}. So, if you have been running your program and you |
| 12664 | wish to debug a core file instead, you must kill the subprocess in which |
| 12665 | the program is running. To do this, use the @code{kill} command |
| 12666 | (@pxref{Kill Process, ,Killing the Child Process}). |
| 12667 | |
| 12668 | @kindex add-symbol-file |
| 12669 | @cindex dynamic linking |
| 12670 | @item add-symbol-file @var{filename} @var{address} |
| 12671 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} |
| 12672 | @itemx add-symbol-file @var{filename} @r{-s}@var{section} @var{address} @dots{} |
| 12673 | The @code{add-symbol-file} command reads additional symbol table |
| 12674 | information from the file @var{filename}. You would use this command |
| 12675 | when @var{filename} has been dynamically loaded (by some other means) |
| 12676 | into the program that is running. @var{address} should be the memory |
| 12677 | address at which the file has been loaded; @value{GDBN} cannot figure |
| 12678 | this out for itself. You can additionally specify an arbitrary number |
| 12679 | of @samp{@r{-s}@var{section} @var{address}} pairs, to give an explicit |
| 12680 | section name and base address for that section. You can specify any |
| 12681 | @var{address} as an expression. |
| 12682 | |
| 12683 | The symbol table of the file @var{filename} is added to the symbol table |
| 12684 | originally read with the @code{symbol-file} command. You can use the |
| 12685 | @code{add-symbol-file} command any number of times; the new symbol data |
| 12686 | thus read keeps adding to the old. To discard all old symbol data |
| 12687 | instead, use the @code{symbol-file} command without any arguments. |
| 12688 | |
| 12689 | @cindex relocatable object files, reading symbols from |
| 12690 | @cindex object files, relocatable, reading symbols from |
| 12691 | @cindex reading symbols from relocatable object files |
| 12692 | @cindex symbols, reading from relocatable object files |
| 12693 | @cindex @file{.o} files, reading symbols from |
| 12694 | Although @var{filename} is typically a shared library file, an |
| 12695 | executable file, or some other object file which has been fully |
| 12696 | relocated for loading into a process, you can also load symbolic |
| 12697 | information from relocatable @file{.o} files, as long as: |
| 12698 | |
| 12699 | @itemize @bullet |
| 12700 | @item |
| 12701 | the file's symbolic information refers only to linker symbols defined in |
| 12702 | that file, not to symbols defined by other object files, |
| 12703 | @item |
| 12704 | every section the file's symbolic information refers to has actually |
| 12705 | been loaded into the inferior, as it appears in the file, and |
| 12706 | @item |
| 12707 | you can determine the address at which every section was loaded, and |
| 12708 | provide these to the @code{add-symbol-file} command. |
| 12709 | @end itemize |
| 12710 | |
| 12711 | @noindent |
| 12712 | Some embedded operating systems, like Sun Chorus and VxWorks, can load |
| 12713 | relocatable files into an already running program; such systems |
| 12714 | typically make the requirements above easy to meet. However, it's |
| 12715 | important to recognize that many native systems use complex link |
| 12716 | procedures (@code{.linkonce} section factoring and C@t{++} constructor table |
| 12717 | assembly, for example) that make the requirements difficult to meet. In |
| 12718 | general, one cannot assume that using @code{add-symbol-file} to read a |
| 12719 | relocatable object file's symbolic information will have the same effect |
| 12720 | as linking the relocatable object file into the program in the normal |
| 12721 | way. |
| 12722 | |
| 12723 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. |
| 12724 | |
| 12725 | @kindex add-symbol-file-from-memory |
| 12726 | @cindex @code{syscall DSO} |
| 12727 | @cindex load symbols from memory |
| 12728 | @item add-symbol-file-from-memory @var{address} |
| 12729 | Load symbols from the given @var{address} in a dynamically loaded |
| 12730 | object file whose image is mapped directly into the inferior's memory. |
| 12731 | For example, the Linux kernel maps a @code{syscall DSO} into each |
| 12732 | process's address space; this DSO provides kernel-specific code for |
| 12733 | some system calls. The argument can be any expression whose |
| 12734 | evaluation yields the address of the file's shared object file header. |
| 12735 | For this command to work, you must have used @code{symbol-file} or |
| 12736 | @code{exec-file} commands in advance. |
| 12737 | |
| 12738 | @kindex add-shared-symbol-files |
| 12739 | @kindex assf |
| 12740 | @item add-shared-symbol-files @var{library-file} |
| 12741 | @itemx assf @var{library-file} |
| 12742 | The @code{add-shared-symbol-files} command can currently be used only |
| 12743 | in the Cygwin build of @value{GDBN} on MS-Windows OS, where it is an |
| 12744 | alias for the @code{dll-symbols} command (@pxref{Cygwin Native}). |
| 12745 | @value{GDBN} automatically looks for shared libraries, however if |
| 12746 | @value{GDBN} does not find yours, you can invoke |
| 12747 | @code{add-shared-symbol-files}. It takes one argument: the shared |
| 12748 | library's file name. @code{assf} is a shorthand alias for |
| 12749 | @code{add-shared-symbol-files}. |
| 12750 | |
| 12751 | @kindex section |
| 12752 | @item section @var{section} @var{addr} |
| 12753 | The @code{section} command changes the base address of the named |
| 12754 | @var{section} of the exec file to @var{addr}. This can be used if the |
| 12755 | exec file does not contain section addresses, (such as in the |
| 12756 | @code{a.out} format), or when the addresses specified in the file |
| 12757 | itself are wrong. Each section must be changed separately. The |
| 12758 | @code{info files} command, described below, lists all the sections and |
| 12759 | their addresses. |
| 12760 | |
| 12761 | @kindex info files |
| 12762 | @kindex info target |
| 12763 | @item info files |
| 12764 | @itemx info target |
| 12765 | @code{info files} and @code{info target} are synonymous; both print the |
| 12766 | current target (@pxref{Targets, ,Specifying a Debugging Target}), |
| 12767 | including the names of the executable and core dump files currently in |
| 12768 | use by @value{GDBN}, and the files from which symbols were loaded. The |
| 12769 | command @code{help target} lists all possible targets rather than |
| 12770 | current ones. |
| 12771 | |
| 12772 | @kindex maint info sections |
| 12773 | @item maint info sections |
| 12774 | Another command that can give you extra information about program sections |
| 12775 | is @code{maint info sections}. In addition to the section information |
| 12776 | displayed by @code{info files}, this command displays the flags and file |
| 12777 | offset of each section in the executable and core dump files. In addition, |
| 12778 | @code{maint info sections} provides the following command options (which |
| 12779 | may be arbitrarily combined): |
| 12780 | |
| 12781 | @table @code |
| 12782 | @item ALLOBJ |
| 12783 | Display sections for all loaded object files, including shared libraries. |
| 12784 | @item @var{sections} |
| 12785 | Display info only for named @var{sections}. |
| 12786 | @item @var{section-flags} |
| 12787 | Display info only for sections for which @var{section-flags} are true. |
| 12788 | The section flags that @value{GDBN} currently knows about are: |
| 12789 | @table @code |
| 12790 | @item ALLOC |
| 12791 | Section will have space allocated in the process when loaded. |
| 12792 | Set for all sections except those containing debug information. |
| 12793 | @item LOAD |
| 12794 | Section will be loaded from the file into the child process memory. |
| 12795 | Set for pre-initialized code and data, clear for @code{.bss} sections. |
| 12796 | @item RELOC |
| 12797 | Section needs to be relocated before loading. |
| 12798 | @item READONLY |
| 12799 | Section cannot be modified by the child process. |
| 12800 | @item CODE |
| 12801 | Section contains executable code only. |
| 12802 | @item DATA |
| 12803 | Section contains data only (no executable code). |
| 12804 | @item ROM |
| 12805 | Section will reside in ROM. |
| 12806 | @item CONSTRUCTOR |
| 12807 | Section contains data for constructor/destructor lists. |
| 12808 | @item HAS_CONTENTS |
| 12809 | Section is not empty. |
| 12810 | @item NEVER_LOAD |
| 12811 | An instruction to the linker to not output the section. |
| 12812 | @item COFF_SHARED_LIBRARY |
| 12813 | A notification to the linker that the section contains |
| 12814 | COFF shared library information. |
| 12815 | @item IS_COMMON |
| 12816 | Section contains common symbols. |
| 12817 | @end table |
| 12818 | @end table |
| 12819 | @kindex set trust-readonly-sections |
| 12820 | @cindex read-only sections |
| 12821 | @item set trust-readonly-sections on |
| 12822 | Tell @value{GDBN} that readonly sections in your object file |
| 12823 | really are read-only (i.e.@: that their contents will not change). |
| 12824 | In that case, @value{GDBN} can fetch values from these sections |
| 12825 | out of the object file, rather than from the target program. |
| 12826 | For some targets (notably embedded ones), this can be a significant |
| 12827 | enhancement to debugging performance. |
| 12828 | |
| 12829 | The default is off. |
| 12830 | |
| 12831 | @item set trust-readonly-sections off |
| 12832 | Tell @value{GDBN} not to trust readonly sections. This means that |
| 12833 | the contents of the section might change while the program is running, |
| 12834 | and must therefore be fetched from the target when needed. |
| 12835 | |
| 12836 | @item show trust-readonly-sections |
| 12837 | Show the current setting of trusting readonly sections. |
| 12838 | @end table |
| 12839 | |
| 12840 | All file-specifying commands allow both absolute and relative file names |
| 12841 | as arguments. @value{GDBN} always converts the file name to an absolute file |
| 12842 | name and remembers it that way. |
| 12843 | |
| 12844 | @cindex shared libraries |
| 12845 | @anchor{Shared Libraries} |
| 12846 | @value{GDBN} supports @sc{gnu}/Linux, MS-Windows, HP-UX, SunOS, SVr4, Irix, |
| 12847 | and IBM RS/6000 AIX shared libraries. |
| 12848 | |
| 12849 | On MS-Windows @value{GDBN} must be linked with the Expat library to support |
| 12850 | shared libraries. @xref{Expat}. |
| 12851 | |
| 12852 | @value{GDBN} automatically loads symbol definitions from shared libraries |
| 12853 | when you use the @code{run} command, or when you examine a core file. |
| 12854 | (Before you issue the @code{run} command, @value{GDBN} does not understand |
| 12855 | references to a function in a shared library, however---unless you are |
| 12856 | debugging a core file). |
| 12857 | |
| 12858 | On HP-UX, if the program loads a library explicitly, @value{GDBN} |
| 12859 | automatically loads the symbols at the time of the @code{shl_load} call. |
| 12860 | |
| 12861 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
| 12862 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared |
| 12863 | @c FIXME...lib; check this from time to time when updating manual |
| 12864 | |
| 12865 | There are times, however, when you may wish to not automatically load |
| 12866 | symbol definitions from shared libraries, such as when they are |
| 12867 | particularly large or there are many of them. |
| 12868 | |
| 12869 | To control the automatic loading of shared library symbols, use the |
| 12870 | commands: |
| 12871 | |
| 12872 | @table @code |
| 12873 | @kindex set auto-solib-add |
| 12874 | @item set auto-solib-add @var{mode} |
| 12875 | If @var{mode} is @code{on}, symbols from all shared object libraries |
| 12876 | will be loaded automatically when the inferior begins execution, you |
| 12877 | attach to an independently started inferior, or when the dynamic linker |
| 12878 | informs @value{GDBN} that a new library has been loaded. If @var{mode} |
| 12879 | is @code{off}, symbols must be loaded manually, using the |
| 12880 | @code{sharedlibrary} command. The default value is @code{on}. |
| 12881 | |
| 12882 | @cindex memory used for symbol tables |
| 12883 | If your program uses lots of shared libraries with debug info that |
| 12884 | takes large amounts of memory, you can decrease the @value{GDBN} |
| 12885 | memory footprint by preventing it from automatically loading the |
| 12886 | symbols from shared libraries. To that end, type @kbd{set |
| 12887 | auto-solib-add off} before running the inferior, then load each |
| 12888 | library whose debug symbols you do need with @kbd{sharedlibrary |
| 12889 | @var{regexp}}, where @var{regexp} is a regular expression that matches |
| 12890 | the libraries whose symbols you want to be loaded. |
| 12891 | |
| 12892 | @kindex show auto-solib-add |
| 12893 | @item show auto-solib-add |
| 12894 | Display the current autoloading mode. |
| 12895 | @end table |
| 12896 | |
| 12897 | @cindex load shared library |
| 12898 | To explicitly load shared library symbols, use the @code{sharedlibrary} |
| 12899 | command: |
| 12900 | |
| 12901 | @table @code |
| 12902 | @kindex info sharedlibrary |
| 12903 | @kindex info share |
| 12904 | @item info share |
| 12905 | @itemx info sharedlibrary |
| 12906 | Print the names of the shared libraries which are currently loaded. |
| 12907 | |
| 12908 | @kindex sharedlibrary |
| 12909 | @kindex share |
| 12910 | @item sharedlibrary @var{regex} |
| 12911 | @itemx share @var{regex} |
| 12912 | Load shared object library symbols for files matching a |
| 12913 | Unix regular expression. |
| 12914 | As with files loaded automatically, it only loads shared libraries |
| 12915 | required by your program for a core file or after typing @code{run}. If |
| 12916 | @var{regex} is omitted all shared libraries required by your program are |
| 12917 | loaded. |
| 12918 | |
| 12919 | @item nosharedlibrary |
| 12920 | @kindex nosharedlibrary |
| 12921 | @cindex unload symbols from shared libraries |
| 12922 | Unload all shared object library symbols. This discards all symbols |
| 12923 | that have been loaded from all shared libraries. Symbols from shared |
| 12924 | libraries that were loaded by explicit user requests are not |
| 12925 | discarded. |
| 12926 | @end table |
| 12927 | |
| 12928 | Sometimes you may wish that @value{GDBN} stops and gives you control |
| 12929 | when any of shared library events happen. Use the @code{set |
| 12930 | stop-on-solib-events} command for this: |
| 12931 | |
| 12932 | @table @code |
| 12933 | @item set stop-on-solib-events |
| 12934 | @kindex set stop-on-solib-events |
| 12935 | This command controls whether @value{GDBN} should give you control |
| 12936 | when the dynamic linker notifies it about some shared library event. |
| 12937 | The most common event of interest is loading or unloading of a new |
| 12938 | shared library. |
| 12939 | |
| 12940 | @item show stop-on-solib-events |
| 12941 | @kindex show stop-on-solib-events |
| 12942 | Show whether @value{GDBN} stops and gives you control when shared |
| 12943 | library events happen. |
| 12944 | @end table |
| 12945 | |
| 12946 | Shared libraries are also supported in many cross or remote debugging |
| 12947 | configurations. @value{GDBN} needs to have access to the target's libraries; |
| 12948 | this can be accomplished either by providing copies of the libraries |
| 12949 | on the host system, or by asking @value{GDBN} to automatically retrieve the |
| 12950 | libraries from the target. If copies of the target libraries are |
| 12951 | provided, they need to be the same as the target libraries, although the |
| 12952 | copies on the target can be stripped as long as the copies on the host are |
| 12953 | not. |
| 12954 | |
| 12955 | @cindex where to look for shared libraries |
| 12956 | For remote debugging, you need to tell @value{GDBN} where the target |
| 12957 | libraries are, so that it can load the correct copies---otherwise, it |
| 12958 | may try to load the host's libraries. @value{GDBN} has two variables |
| 12959 | to specify the search directories for target libraries. |
| 12960 | |
| 12961 | @table @code |
| 12962 | @cindex prefix for shared library file names |
| 12963 | @cindex system root, alternate |
| 12964 | @kindex set solib-absolute-prefix |
| 12965 | @kindex set sysroot |
| 12966 | @item set sysroot @var{path} |
| 12967 | Use @var{path} as the system root for the program being debugged. Any |
| 12968 | absolute shared library paths will be prefixed with @var{path}; many |
| 12969 | runtime loaders store the absolute paths to the shared library in the |
| 12970 | target program's memory. If you use @code{set sysroot} to find shared |
| 12971 | libraries, they need to be laid out in the same way that they are on |
| 12972 | the target, with e.g.@: a @file{/lib} and @file{/usr/lib} hierarchy |
| 12973 | under @var{path}. |
| 12974 | |
| 12975 | If @var{path} starts with the sequence @file{remote:}, @value{GDBN} will |
| 12976 | retrieve the target libraries from the remote system. This is only |
| 12977 | supported when using a remote target that supports the @code{remote get} |
| 12978 | command (@pxref{File Transfer,,Sending files to a remote system}). |
| 12979 | The part of @var{path} following the initial @file{remote:} |
| 12980 | (if present) is used as system root prefix on the remote file system. |
| 12981 | @footnote{If you want to specify a local system root using a directory |
| 12982 | that happens to be named @file{remote:}, you need to use some equivalent |
| 12983 | variant of the name like @file{./remote:}.} |
| 12984 | |
| 12985 | The @code{set solib-absolute-prefix} command is an alias for @code{set |
| 12986 | sysroot}. |
| 12987 | |
| 12988 | @cindex default system root |
| 12989 | @cindex @samp{--with-sysroot} |
| 12990 | You can set the default system root by using the configure-time |
| 12991 | @samp{--with-sysroot} option. If the system root is inside |
| 12992 | @value{GDBN}'s configured binary prefix (set with @samp{--prefix} or |
| 12993 | @samp{--exec-prefix}), then the default system root will be updated |
| 12994 | automatically if the installed @value{GDBN} is moved to a new |
| 12995 | location. |
| 12996 | |
| 12997 | @kindex show sysroot |
| 12998 | @item show sysroot |
| 12999 | Display the current shared library prefix. |
| 13000 | |
| 13001 | @kindex set solib-search-path |
| 13002 | @item set solib-search-path @var{path} |
| 13003 | If this variable is set, @var{path} is a colon-separated list of |
| 13004 | directories to search for shared libraries. @samp{solib-search-path} |
| 13005 | is used after @samp{sysroot} fails to locate the library, or if the |
| 13006 | path to the library is relative instead of absolute. If you want to |
| 13007 | use @samp{solib-search-path} instead of @samp{sysroot}, be sure to set |
| 13008 | @samp{sysroot} to a nonexistent directory to prevent @value{GDBN} from |
| 13009 | finding your host's libraries. @samp{sysroot} is preferred; setting |
| 13010 | it to a nonexistent directory may interfere with automatic loading |
| 13011 | of shared library symbols. |
| 13012 | |
| 13013 | @kindex show solib-search-path |
| 13014 | @item show solib-search-path |
| 13015 | Display the current shared library search path. |
| 13016 | @end table |
| 13017 | |
| 13018 | |
| 13019 | @node Separate Debug Files |
| 13020 | @section Debugging Information in Separate Files |
| 13021 | @cindex separate debugging information files |
| 13022 | @cindex debugging information in separate files |
| 13023 | @cindex @file{.debug} subdirectories |
| 13024 | @cindex debugging information directory, global |
| 13025 | @cindex global debugging information directory |
| 13026 | @cindex build ID, and separate debugging files |
| 13027 | @cindex @file{.build-id} directory |
| 13028 | |
| 13029 | @value{GDBN} allows you to put a program's debugging information in a |
| 13030 | file separate from the executable itself, in a way that allows |
| 13031 | @value{GDBN} to find and load the debugging information automatically. |
| 13032 | Since debugging information can be very large---sometimes larger |
| 13033 | than the executable code itself---some systems distribute debugging |
| 13034 | information for their executables in separate files, which users can |
| 13035 | install only when they need to debug a problem. |
| 13036 | |
| 13037 | @value{GDBN} supports two ways of specifying the separate debug info |
| 13038 | file: |
| 13039 | |
| 13040 | @itemize @bullet |
| 13041 | @item |
| 13042 | The executable contains a @dfn{debug link} that specifies the name of |
| 13043 | the separate debug info file. The separate debug file's name is |
| 13044 | usually @file{@var{executable}.debug}, where @var{executable} is the |
| 13045 | name of the corresponding executable file without leading directories |
| 13046 | (e.g., @file{ls.debug} for @file{/usr/bin/ls}). In addition, the |
| 13047 | debug link specifies a CRC32 checksum for the debug file, which |
| 13048 | @value{GDBN} uses to validate that the executable and the debug file |
| 13049 | came from the same build. |
| 13050 | |
| 13051 | @item |
| 13052 | The executable contains a @dfn{build ID}, a unique bit string that is |
| 13053 | also present in the corresponding debug info file. (This is supported |
| 13054 | only on some operating systems, notably those which use the ELF format |
| 13055 | for binary files and the @sc{gnu} Binutils.) For more details about |
| 13056 | this feature, see the description of the @option{--build-id} |
| 13057 | command-line option in @ref{Options, , Command Line Options, ld.info, |
| 13058 | The GNU Linker}. The debug info file's name is not specified |
| 13059 | explicitly by the build ID, but can be computed from the build ID, see |
| 13060 | below. |
| 13061 | @end itemize |
| 13062 | |
| 13063 | Depending on the way the debug info file is specified, @value{GDBN} |
| 13064 | uses two different methods of looking for the debug file: |
| 13065 | |
| 13066 | @itemize @bullet |
| 13067 | @item |
| 13068 | For the ``debug link'' method, @value{GDBN} looks up the named file in |
| 13069 | the directory of the executable file, then in a subdirectory of that |
| 13070 | directory named @file{.debug}, and finally under the global debug |
| 13071 | directory, in a subdirectory whose name is identical to the leading |
| 13072 | directories of the executable's absolute file name. |
| 13073 | |
| 13074 | @item |
| 13075 | For the ``build ID'' method, @value{GDBN} looks in the |
| 13076 | @file{.build-id} subdirectory of the global debug directory for a file |
| 13077 | named @file{@var{nn}/@var{nnnnnnnn}.debug}, where @var{nn} are the |
| 13078 | first 2 hex characters of the build ID bit string, and @var{nnnnnnnn} |
| 13079 | are the rest of the bit string. (Real build ID strings are 32 or more |
| 13080 | hex characters, not 10.) |
| 13081 | @end itemize |
| 13082 | |
| 13083 | So, for example, suppose you ask @value{GDBN} to debug |
| 13084 | @file{/usr/bin/ls}, which has a debug link that specifies the |
| 13085 | file @file{ls.debug}, and a build ID whose value in hex is |
| 13086 | @code{abcdef1234}. If the global debug directory is |
| 13087 | @file{/usr/lib/debug}, then @value{GDBN} will look for the following |
| 13088 | debug information files, in the indicated order: |
| 13089 | |
| 13090 | @itemize @minus |
| 13091 | @item |
| 13092 | @file{/usr/lib/debug/.build-id/ab/cdef1234.debug} |
| 13093 | @item |
| 13094 | @file{/usr/bin/ls.debug} |
| 13095 | @item |
| 13096 | @file{/usr/bin/.debug/ls.debug} |
| 13097 | @item |
| 13098 | @file{/usr/lib/debug/usr/bin/ls.debug}. |
| 13099 | @end itemize |
| 13100 | |
| 13101 | You can set the global debugging info directory's name, and view the |
| 13102 | name @value{GDBN} is currently using. |
| 13103 | |
| 13104 | @table @code |
| 13105 | |
| 13106 | @kindex set debug-file-directory |
| 13107 | @item set debug-file-directory @var{directory} |
| 13108 | Set the directory which @value{GDBN} searches for separate debugging |
| 13109 | information files to @var{directory}. |
| 13110 | |
| 13111 | @kindex show debug-file-directory |
| 13112 | @item show debug-file-directory |
| 13113 | Show the directory @value{GDBN} searches for separate debugging |
| 13114 | information files. |
| 13115 | |
| 13116 | @end table |
| 13117 | |
| 13118 | @cindex @code{.gnu_debuglink} sections |
| 13119 | @cindex debug link sections |
| 13120 | A debug link is a special section of the executable file named |
| 13121 | @code{.gnu_debuglink}. The section must contain: |
| 13122 | |
| 13123 | @itemize |
| 13124 | @item |
| 13125 | A filename, with any leading directory components removed, followed by |
| 13126 | a zero byte, |
| 13127 | @item |
| 13128 | zero to three bytes of padding, as needed to reach the next four-byte |
| 13129 | boundary within the section, and |
| 13130 | @item |
| 13131 | a four-byte CRC checksum, stored in the same endianness used for the |
| 13132 | executable file itself. The checksum is computed on the debugging |
| 13133 | information file's full contents by the function given below, passing |
| 13134 | zero as the @var{crc} argument. |
| 13135 | @end itemize |
| 13136 | |
| 13137 | Any executable file format can carry a debug link, as long as it can |
| 13138 | contain a section named @code{.gnu_debuglink} with the contents |
| 13139 | described above. |
| 13140 | |
| 13141 | @cindex @code{.note.gnu.build-id} sections |
| 13142 | @cindex build ID sections |
| 13143 | The build ID is a special section in the executable file (and in other |
| 13144 | ELF binary files that @value{GDBN} may consider). This section is |
| 13145 | often named @code{.note.gnu.build-id}, but that name is not mandatory. |
| 13146 | It contains unique identification for the built files---the ID remains |
| 13147 | the same across multiple builds of the same build tree. The default |
| 13148 | algorithm SHA1 produces 160 bits (40 hexadecimal characters) of the |
| 13149 | content for the build ID string. The same section with an identical |
| 13150 | value is present in the original built binary with symbols, in its |
| 13151 | stripped variant, and in the separate debugging information file. |
| 13152 | |
| 13153 | The debugging information file itself should be an ordinary |
| 13154 | executable, containing a full set of linker symbols, sections, and |
| 13155 | debugging information. The sections of the debugging information file |
| 13156 | should have the same names, addresses, and sizes as the original file, |
| 13157 | but they need not contain any data---much like a @code{.bss} section |
| 13158 | in an ordinary executable. |
| 13159 | |
| 13160 | The @sc{gnu} binary utilities (Binutils) package includes the |
| 13161 | @samp{objcopy} utility that can produce |
| 13162 | the separated executable / debugging information file pairs using the |
| 13163 | following commands: |
| 13164 | |
| 13165 | @smallexample |
| 13166 | @kbd{objcopy --only-keep-debug foo foo.debug} |
| 13167 | @kbd{strip -g foo} |
| 13168 | @end smallexample |
| 13169 | |
| 13170 | @noindent |
| 13171 | These commands remove the debugging |
| 13172 | information from the executable file @file{foo} and place it in the file |
| 13173 | @file{foo.debug}. You can use the first, second or both methods to link the |
| 13174 | two files: |
| 13175 | |
| 13176 | @itemize @bullet |
| 13177 | @item |
| 13178 | The debug link method needs the following additional command to also leave |
| 13179 | behind a debug link in @file{foo}: |
| 13180 | |
| 13181 | @smallexample |
| 13182 | @kbd{objcopy --add-gnu-debuglink=foo.debug foo} |
| 13183 | @end smallexample |
| 13184 | |
| 13185 | Ulrich Drepper's @file{elfutils} package, starting with version 0.53, contains |
| 13186 | a version of the @code{strip} command such that the command @kbd{strip foo -f |
| 13187 | foo.debug} has the same functionality as the two @code{objcopy} commands and |
| 13188 | the @code{ln -s} command above, together. |
| 13189 | |
| 13190 | @item |
| 13191 | Build ID gets embedded into the main executable using @code{ld --build-id} or |
| 13192 | the @value{NGCC} counterpart @code{gcc -Wl,--build-id}. Build ID support plus |
| 13193 | compatibility fixes for debug files separation are present in @sc{gnu} binary |
| 13194 | utilities (Binutils) package since version 2.18. |
| 13195 | @end itemize |
| 13196 | |
| 13197 | @noindent |
| 13198 | |
| 13199 | Since there are many different ways to compute CRC's for the debug |
| 13200 | link (different polynomials, reversals, byte ordering, etc.), the |
| 13201 | simplest way to describe the CRC used in @code{.gnu_debuglink} |
| 13202 | sections is to give the complete code for a function that computes it: |
| 13203 | |
| 13204 | @kindex gnu_debuglink_crc32 |
| 13205 | @smallexample |
| 13206 | unsigned long |
| 13207 | gnu_debuglink_crc32 (unsigned long crc, |
| 13208 | unsigned char *buf, size_t len) |
| 13209 | @{ |
| 13210 | static const unsigned long crc32_table[256] = |
| 13211 | @{ |
| 13212 | 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, |
| 13213 | 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, |
| 13214 | 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, |
| 13215 | 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, |
| 13216 | 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, |
| 13217 | 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, |
| 13218 | 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, |
| 13219 | 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, |
| 13220 | 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, |
| 13221 | 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, |
| 13222 | 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, |
| 13223 | 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, |
| 13224 | 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, |
| 13225 | 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, |
| 13226 | 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, |
| 13227 | 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, |
| 13228 | 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, |
| 13229 | 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, |
| 13230 | 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, |
| 13231 | 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, |
| 13232 | 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, |
| 13233 | 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, |
| 13234 | 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, |
| 13235 | 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, |
| 13236 | 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, |
| 13237 | 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, |
| 13238 | 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, |
| 13239 | 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, |
| 13240 | 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, |
| 13241 | 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, |
| 13242 | 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, |
| 13243 | 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, |
| 13244 | 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, |
| 13245 | 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, |
| 13246 | 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, |
| 13247 | 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, |
| 13248 | 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, |
| 13249 | 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, |
| 13250 | 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, |
| 13251 | 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, |
| 13252 | 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, |
| 13253 | 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, |
| 13254 | 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, |
| 13255 | 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, |
| 13256 | 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, |
| 13257 | 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, |
| 13258 | 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, |
| 13259 | 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, |
| 13260 | 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, |
| 13261 | 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, |
| 13262 | 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, |
| 13263 | 0x2d02ef8d |
| 13264 | @}; |
| 13265 | unsigned char *end; |
| 13266 | |
| 13267 | crc = ~crc & 0xffffffff; |
| 13268 | for (end = buf + len; buf < end; ++buf) |
| 13269 | crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8); |
| 13270 | return ~crc & 0xffffffff; |
| 13271 | @} |
| 13272 | @end smallexample |
| 13273 | |
| 13274 | @noindent |
| 13275 | This computation does not apply to the ``build ID'' method. |
| 13276 | |
| 13277 | |
| 13278 | @node Symbol Errors |
| 13279 | @section Errors Reading Symbol Files |
| 13280 | |
| 13281 | While reading a symbol file, @value{GDBN} occasionally encounters problems, |
| 13282 | such as symbol types it does not recognize, or known bugs in compiler |
| 13283 | output. By default, @value{GDBN} does not notify you of such problems, since |
| 13284 | they are relatively common and primarily of interest to people |
| 13285 | debugging compilers. If you are interested in seeing information |
| 13286 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print |
| 13287 | only one message about each such type of problem, no matter how many |
| 13288 | times the problem occurs; or you can ask @value{GDBN} to print more messages, |
| 13289 | to see how many times the problems occur, with the @code{set |
| 13290 | complaints} command (@pxref{Messages/Warnings, ,Optional Warnings and |
| 13291 | Messages}). |
| 13292 | |
| 13293 | The messages currently printed, and their meanings, include: |
| 13294 | |
| 13295 | @table @code |
| 13296 | @item inner block not inside outer block in @var{symbol} |
| 13297 | |
| 13298 | The symbol information shows where symbol scopes begin and end |
| 13299 | (such as at the start of a function or a block of statements). This |
| 13300 | error indicates that an inner scope block is not fully contained |
| 13301 | in its outer scope blocks. |
| 13302 | |
| 13303 | @value{GDBN} circumvents the problem by treating the inner block as if it had |
| 13304 | the same scope as the outer block. In the error message, @var{symbol} |
| 13305 | may be shown as ``@code{(don't know)}'' if the outer block is not a |
| 13306 | function. |
| 13307 | |
| 13308 | @item block at @var{address} out of order |
| 13309 | |
| 13310 | The symbol information for symbol scope blocks should occur in |
| 13311 | order of increasing addresses. This error indicates that it does not |
| 13312 | do so. |
| 13313 | |
| 13314 | @value{GDBN} does not circumvent this problem, and has trouble |
| 13315 | locating symbols in the source file whose symbols it is reading. (You |
| 13316 | can often determine what source file is affected by specifying |
| 13317 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional Warnings and |
| 13318 | Messages}.) |
| 13319 | |
| 13320 | @item bad block start address patched |
| 13321 | |
| 13322 | The symbol information for a symbol scope block has a start address |
| 13323 | smaller than the address of the preceding source line. This is known |
| 13324 | to occur in the SunOS 4.1.1 (and earlier) C compiler. |
| 13325 | |
| 13326 | @value{GDBN} circumvents the problem by treating the symbol scope block as |
| 13327 | starting on the previous source line. |
| 13328 | |
| 13329 | @item bad string table offset in symbol @var{n} |
| 13330 | |
| 13331 | @cindex foo |
| 13332 | Symbol number @var{n} contains a pointer into the string table which is |
| 13333 | larger than the size of the string table. |
| 13334 | |
| 13335 | @value{GDBN} circumvents the problem by considering the symbol to have the |
| 13336 | name @code{foo}, which may cause other problems if many symbols end up |
| 13337 | with this name. |
| 13338 | |
| 13339 | @item unknown symbol type @code{0x@var{nn}} |
| 13340 | |
| 13341 | The symbol information contains new data types that @value{GDBN} does |
| 13342 | not yet know how to read. @code{0x@var{nn}} is the symbol type of the |
| 13343 | uncomprehended information, in hexadecimal. |
| 13344 | |
| 13345 | @value{GDBN} circumvents the error by ignoring this symbol information. |
| 13346 | This usually allows you to debug your program, though certain symbols |
| 13347 | are not accessible. If you encounter such a problem and feel like |
| 13348 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint |
| 13349 | on @code{complain}, then go up to the function @code{read_dbx_symtab} |
| 13350 | and examine @code{*bufp} to see the symbol. |
| 13351 | |
| 13352 | @item stub type has NULL name |
| 13353 | |
| 13354 | @value{GDBN} could not find the full definition for a struct or class. |
| 13355 | |
| 13356 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
| 13357 | The symbol information for a C@t{++} member function is missing some |
| 13358 | information that recent versions of the compiler should have output for |
| 13359 | it. |
| 13360 | |
| 13361 | @item info mismatch between compiler and debugger |
| 13362 | |
| 13363 | @value{GDBN} could not parse a type specification output by the compiler. |
| 13364 | |
| 13365 | @end table |
| 13366 | |
| 13367 | @node Targets |
| 13368 | @chapter Specifying a Debugging Target |
| 13369 | |
| 13370 | @cindex debugging target |
| 13371 | A @dfn{target} is the execution environment occupied by your program. |
| 13372 | |
| 13373 | Often, @value{GDBN} runs in the same host environment as your program; |
| 13374 | in that case, the debugging target is specified as a side effect when |
| 13375 | you use the @code{file} or @code{core} commands. When you need more |
| 13376 | flexibility---for example, running @value{GDBN} on a physically separate |
| 13377 | host, or controlling a standalone system over a serial port or a |
| 13378 | realtime system over a TCP/IP connection---you can use the @code{target} |
| 13379 | command to specify one of the target types configured for @value{GDBN} |
| 13380 | (@pxref{Target Commands, ,Commands for Managing Targets}). |
| 13381 | |
| 13382 | @cindex target architecture |
| 13383 | It is possible to build @value{GDBN} for several different @dfn{target |
| 13384 | architectures}. When @value{GDBN} is built like that, you can choose |
| 13385 | one of the available architectures with the @kbd{set architecture} |
| 13386 | command. |
| 13387 | |
| 13388 | @table @code |
| 13389 | @kindex set architecture |
| 13390 | @kindex show architecture |
| 13391 | @item set architecture @var{arch} |
| 13392 | This command sets the current target architecture to @var{arch}. The |
| 13393 | value of @var{arch} can be @code{"auto"}, in addition to one of the |
| 13394 | supported architectures. |
| 13395 | |
| 13396 | @item show architecture |
| 13397 | Show the current target architecture. |
| 13398 | |
| 13399 | @item set processor |
| 13400 | @itemx processor |
| 13401 | @kindex set processor |
| 13402 | @kindex show processor |
| 13403 | These are alias commands for, respectively, @code{set architecture} |
| 13404 | and @code{show architecture}. |
| 13405 | @end table |
| 13406 | |
| 13407 | @menu |
| 13408 | * Active Targets:: Active targets |
| 13409 | * Target Commands:: Commands for managing targets |
| 13410 | * Byte Order:: Choosing target byte order |
| 13411 | @end menu |
| 13412 | |
| 13413 | @node Active Targets |
| 13414 | @section Active Targets |
| 13415 | |
| 13416 | @cindex stacking targets |
| 13417 | @cindex active targets |
| 13418 | @cindex multiple targets |
| 13419 | |
| 13420 | There are three classes of targets: processes, core files, and |
| 13421 | executable files. @value{GDBN} can work concurrently on up to three |
| 13422 | active targets, one in each class. This allows you to (for example) |
| 13423 | start a process and inspect its activity without abandoning your work on |
| 13424 | a core file. |
| 13425 | |
| 13426 | For example, if you execute @samp{gdb a.out}, then the executable file |
| 13427 | @code{a.out} is the only active target. If you designate a core file as |
| 13428 | well---presumably from a prior run that crashed and coredumped---then |
| 13429 | @value{GDBN} has two active targets and uses them in tandem, looking |
| 13430 | first in the corefile target, then in the executable file, to satisfy |
| 13431 | requests for memory addresses. (Typically, these two classes of target |
| 13432 | are complementary, since core files contain only a program's |
| 13433 | read-write memory---variables and so on---plus machine status, while |
| 13434 | executable files contain only the program text and initialized data.) |
| 13435 | |
| 13436 | When you type @code{run}, your executable file becomes an active process |
| 13437 | target as well. When a process target is active, all @value{GDBN} |
| 13438 | commands requesting memory addresses refer to that target; addresses in |
| 13439 | an active core file or executable file target are obscured while the |
| 13440 | process target is active. |
| 13441 | |
| 13442 | Use the @code{core-file} and @code{exec-file} commands to select a new |
| 13443 | core file or executable target (@pxref{Files, ,Commands to Specify |
| 13444 | Files}). To specify as a target a process that is already running, use |
| 13445 | the @code{attach} command (@pxref{Attach, ,Debugging an Already-running |
| 13446 | Process}). |
| 13447 | |
| 13448 | @node Target Commands |
| 13449 | @section Commands for Managing Targets |
| 13450 | |
| 13451 | @table @code |
| 13452 | @item target @var{type} @var{parameters} |
| 13453 | Connects the @value{GDBN} host environment to a target machine or |
| 13454 | process. A target is typically a protocol for talking to debugging |
| 13455 | facilities. You use the argument @var{type} to specify the type or |
| 13456 | protocol of the target machine. |
| 13457 | |
| 13458 | Further @var{parameters} are interpreted by the target protocol, but |
| 13459 | typically include things like device names or host names to connect |
| 13460 | with, process numbers, and baud rates. |
| 13461 | |
| 13462 | The @code{target} command does not repeat if you press @key{RET} again |
| 13463 | after executing the command. |
| 13464 | |
| 13465 | @kindex help target |
| 13466 | @item help target |
| 13467 | Displays the names of all targets available. To display targets |
| 13468 | currently selected, use either @code{info target} or @code{info files} |
| 13469 | (@pxref{Files, ,Commands to Specify Files}). |
| 13470 | |
| 13471 | @item help target @var{name} |
| 13472 | Describe a particular target, including any parameters necessary to |
| 13473 | select it. |
| 13474 | |
| 13475 | @kindex set gnutarget |
| 13476 | @item set gnutarget @var{args} |
| 13477 | @value{GDBN} uses its own library BFD to read your files. @value{GDBN} |
| 13478 | knows whether it is reading an @dfn{executable}, |
| 13479 | a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format |
| 13480 | with the @code{set gnutarget} command. Unlike most @code{target} commands, |
| 13481 | with @code{gnutarget} the @code{target} refers to a program, not a machine. |
| 13482 | |
| 13483 | @quotation |
| 13484 | @emph{Warning:} To specify a file format with @code{set gnutarget}, |
| 13485 | you must know the actual BFD name. |
| 13486 | @end quotation |
| 13487 | |
| 13488 | @noindent |
| 13489 | @xref{Files, , Commands to Specify Files}. |
| 13490 | |
| 13491 | @kindex show gnutarget |
| 13492 | @item show gnutarget |
| 13493 | Use the @code{show gnutarget} command to display what file format |
| 13494 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, |
| 13495 | @value{GDBN} will determine the file format for each file automatically, |
| 13496 | and @code{show gnutarget} displays @samp{The current BDF target is "auto"}. |
| 13497 | @end table |
| 13498 | |
| 13499 | @cindex common targets |
| 13500 | Here are some common targets (available, or not, depending on the GDB |
| 13501 | configuration): |
| 13502 | |
| 13503 | @table @code |
| 13504 | @kindex target |
| 13505 | @item target exec @var{program} |
| 13506 | @cindex executable file target |
| 13507 | An executable file. @samp{target exec @var{program}} is the same as |
| 13508 | @samp{exec-file @var{program}}. |
| 13509 | |
| 13510 | @item target core @var{filename} |
| 13511 | @cindex core dump file target |
| 13512 | A core dump file. @samp{target core @var{filename}} is the same as |
| 13513 | @samp{core-file @var{filename}}. |
| 13514 | |
| 13515 | @item target remote @var{medium} |
| 13516 | @cindex remote target |
| 13517 | A remote system connected to @value{GDBN} via a serial line or network |
| 13518 | connection. This command tells @value{GDBN} to use its own remote |
| 13519 | protocol over @var{medium} for debugging. @xref{Remote Debugging}. |
| 13520 | |
| 13521 | For example, if you have a board connected to @file{/dev/ttya} on the |
| 13522 | machine running @value{GDBN}, you could say: |
| 13523 | |
| 13524 | @smallexample |
| 13525 | target remote /dev/ttya |
| 13526 | @end smallexample |
| 13527 | |
| 13528 | @code{target remote} supports the @code{load} command. This is only |
| 13529 | useful if you have some other way of getting the stub to the target |
| 13530 | system, and you can put it somewhere in memory where it won't get |
| 13531 | clobbered by the download. |
| 13532 | |
| 13533 | @item target sim |
| 13534 | @cindex built-in simulator target |
| 13535 | Builtin CPU simulator. @value{GDBN} includes simulators for most architectures. |
| 13536 | In general, |
| 13537 | @smallexample |
| 13538 | target sim |
| 13539 | load |
| 13540 | run |
| 13541 | @end smallexample |
| 13542 | @noindent |
| 13543 | works; however, you cannot assume that a specific memory map, device |
| 13544 | drivers, or even basic I/O is available, although some simulators do |
| 13545 | provide these. For info about any processor-specific simulator details, |
| 13546 | see the appropriate section in @ref{Embedded Processors, ,Embedded |
| 13547 | Processors}. |
| 13548 | |
| 13549 | @end table |
| 13550 | |
| 13551 | Some configurations may include these targets as well: |
| 13552 | |
| 13553 | @table @code |
| 13554 | |
| 13555 | @item target nrom @var{dev} |
| 13556 | @cindex NetROM ROM emulator target |
| 13557 | NetROM ROM emulator. This target only supports downloading. |
| 13558 | |
| 13559 | @end table |
| 13560 | |
| 13561 | Different targets are available on different configurations of @value{GDBN}; |
| 13562 | your configuration may have more or fewer targets. |
| 13563 | |
| 13564 | Many remote targets require you to download the executable's code once |
| 13565 | you've successfully established a connection. You may wish to control |
| 13566 | various aspects of this process. |
| 13567 | |
| 13568 | @table @code |
| 13569 | |
| 13570 | @item set hash |
| 13571 | @kindex set hash@r{, for remote monitors} |
| 13572 | @cindex hash mark while downloading |
| 13573 | This command controls whether a hash mark @samp{#} is displayed while |
| 13574 | downloading a file to the remote monitor. If on, a hash mark is |
| 13575 | displayed after each S-record is successfully downloaded to the |
| 13576 | monitor. |
| 13577 | |
| 13578 | @item show hash |
| 13579 | @kindex show hash@r{, for remote monitors} |
| 13580 | Show the current status of displaying the hash mark. |
| 13581 | |
| 13582 | @item set debug monitor |
| 13583 | @kindex set debug monitor |
| 13584 | @cindex display remote monitor communications |
| 13585 | Enable or disable display of communications messages between |
| 13586 | @value{GDBN} and the remote monitor. |
| 13587 | |
| 13588 | @item show debug monitor |
| 13589 | @kindex show debug monitor |
| 13590 | Show the current status of displaying communications between |
| 13591 | @value{GDBN} and the remote monitor. |
| 13592 | @end table |
| 13593 | |
| 13594 | @table @code |
| 13595 | |
| 13596 | @kindex load @var{filename} |
| 13597 | @item load @var{filename} |
| 13598 | @anchor{load} |
| 13599 | Depending on what remote debugging facilities are configured into |
| 13600 | @value{GDBN}, the @code{load} command may be available. Where it exists, it |
| 13601 | is meant to make @var{filename} (an executable) available for debugging |
| 13602 | on the remote system---by downloading, or dynamic linking, for example. |
| 13603 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like |
| 13604 | the @code{add-symbol-file} command. |
| 13605 | |
| 13606 | If your @value{GDBN} does not have a @code{load} command, attempting to |
| 13607 | execute it gets the error message ``@code{You can't do that when your |
| 13608 | target is @dots{}}'' |
| 13609 | |
| 13610 | The file is loaded at whatever address is specified in the executable. |
| 13611 | For some object file formats, you can specify the load address when you |
| 13612 | link the program; for other formats, like a.out, the object file format |
| 13613 | specifies a fixed address. |
| 13614 | @c FIXME! This would be a good place for an xref to the GNU linker doc. |
| 13615 | |
| 13616 | Depending on the remote side capabilities, @value{GDBN} may be able to |
| 13617 | load programs into flash memory. |
| 13618 | |
| 13619 | @code{load} does not repeat if you press @key{RET} again after using it. |
| 13620 | @end table |
| 13621 | |
| 13622 | @node Byte Order |
| 13623 | @section Choosing Target Byte Order |
| 13624 | |
| 13625 | @cindex choosing target byte order |
| 13626 | @cindex target byte order |
| 13627 | |
| 13628 | Some types of processors, such as the MIPS, PowerPC, and Renesas SH, |
| 13629 | offer the ability to run either big-endian or little-endian byte |
| 13630 | orders. Usually the executable or symbol will include a bit to |
| 13631 | designate the endian-ness, and you will not need to worry about |
| 13632 | which to use. However, you may still find it useful to adjust |
| 13633 | @value{GDBN}'s idea of processor endian-ness manually. |
| 13634 | |
| 13635 | @table @code |
| 13636 | @kindex set endian |
| 13637 | @item set endian big |
| 13638 | Instruct @value{GDBN} to assume the target is big-endian. |
| 13639 | |
| 13640 | @item set endian little |
| 13641 | Instruct @value{GDBN} to assume the target is little-endian. |
| 13642 | |
| 13643 | @item set endian auto |
| 13644 | Instruct @value{GDBN} to use the byte order associated with the |
| 13645 | executable. |
| 13646 | |
| 13647 | @item show endian |
| 13648 | Display @value{GDBN}'s current idea of the target byte order. |
| 13649 | |
| 13650 | @end table |
| 13651 | |
| 13652 | Note that these commands merely adjust interpretation of symbolic |
| 13653 | data on the host, and that they have absolutely no effect on the |
| 13654 | target system. |
| 13655 | |
| 13656 | |
| 13657 | @node Remote Debugging |
| 13658 | @chapter Debugging Remote Programs |
| 13659 | @cindex remote debugging |
| 13660 | |
| 13661 | If you are trying to debug a program running on a machine that cannot run |
| 13662 | @value{GDBN} in the usual way, it is often useful to use remote debugging. |
| 13663 | For example, you might use remote debugging on an operating system kernel, |
| 13664 | or on a small system which does not have a general purpose operating system |
| 13665 | powerful enough to run a full-featured debugger. |
| 13666 | |
| 13667 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces |
| 13668 | to make this work with particular debugging targets. In addition, |
| 13669 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, |
| 13670 | but not specific to any particular target system) which you can use if you |
| 13671 | write the remote stubs---the code that runs on the remote system to |
| 13672 | communicate with @value{GDBN}. |
| 13673 | |
| 13674 | Other remote targets may be available in your |
| 13675 | configuration of @value{GDBN}; use @code{help target} to list them. |
| 13676 | |
| 13677 | @menu |
| 13678 | * Connecting:: Connecting to a remote target |
| 13679 | * File Transfer:: Sending files to a remote system |
| 13680 | * Server:: Using the gdbserver program |
| 13681 | * Remote Configuration:: Remote configuration |
| 13682 | * Remote Stub:: Implementing a remote stub |
| 13683 | @end menu |
| 13684 | |
| 13685 | @node Connecting |
| 13686 | @section Connecting to a Remote Target |
| 13687 | |
| 13688 | On the @value{GDBN} host machine, you will need an unstripped copy of |
| 13689 | your program, since @value{GDBN} needs symbol and debugging information. |
| 13690 | Start up @value{GDBN} as usual, using the name of the local copy of your |
| 13691 | program as the first argument. |
| 13692 | |
| 13693 | @cindex @code{target remote} |
| 13694 | @value{GDBN} can communicate with the target over a serial line, or |
| 13695 | over an @acronym{IP} network using @acronym{TCP} or @acronym{UDP}. In |
| 13696 | each case, @value{GDBN} uses the same protocol for debugging your |
| 13697 | program; only the medium carrying the debugging packets varies. The |
| 13698 | @code{target remote} command establishes a connection to the target. |
| 13699 | Its arguments indicate which medium to use: |
| 13700 | |
| 13701 | @table @code |
| 13702 | |
| 13703 | @item target remote @var{serial-device} |
| 13704 | @cindex serial line, @code{target remote} |
| 13705 | Use @var{serial-device} to communicate with the target. For example, |
| 13706 | to use a serial line connected to the device named @file{/dev/ttyb}: |
| 13707 | |
| 13708 | @smallexample |
| 13709 | target remote /dev/ttyb |
| 13710 | @end smallexample |
| 13711 | |
| 13712 | If you're using a serial line, you may want to give @value{GDBN} the |
| 13713 | @w{@samp{--baud}} option, or use the @code{set remotebaud} command |
| 13714 | (@pxref{Remote Configuration, set remotebaud}) before the |
| 13715 | @code{target} command. |
| 13716 | |
| 13717 | @item target remote @code{@var{host}:@var{port}} |
| 13718 | @itemx target remote @code{tcp:@var{host}:@var{port}} |
| 13719 | @cindex @acronym{TCP} port, @code{target remote} |
| 13720 | Debug using a @acronym{TCP} connection to @var{port} on @var{host}. |
| 13721 | The @var{host} may be either a host name or a numeric @acronym{IP} |
| 13722 | address; @var{port} must be a decimal number. The @var{host} could be |
| 13723 | the target machine itself, if it is directly connected to the net, or |
| 13724 | it might be a terminal server which in turn has a serial line to the |
| 13725 | target. |
| 13726 | |
| 13727 | For example, to connect to port 2828 on a terminal server named |
| 13728 | @code{manyfarms}: |
| 13729 | |
| 13730 | @smallexample |
| 13731 | target remote manyfarms:2828 |
| 13732 | @end smallexample |
| 13733 | |
| 13734 | If your remote target is actually running on the same machine as your |
| 13735 | debugger session (e.g.@: a simulator for your target running on the |
| 13736 | same host), you can omit the hostname. For example, to connect to |
| 13737 | port 1234 on your local machine: |
| 13738 | |
| 13739 | @smallexample |
| 13740 | target remote :1234 |
| 13741 | @end smallexample |
| 13742 | @noindent |
| 13743 | |
| 13744 | Note that the colon is still required here. |
| 13745 | |
| 13746 | @item target remote @code{udp:@var{host}:@var{port}} |
| 13747 | @cindex @acronym{UDP} port, @code{target remote} |
| 13748 | Debug using @acronym{UDP} packets to @var{port} on @var{host}. For example, to |
| 13749 | connect to @acronym{UDP} port 2828 on a terminal server named @code{manyfarms}: |
| 13750 | |
| 13751 | @smallexample |
| 13752 | target remote udp:manyfarms:2828 |
| 13753 | @end smallexample |
| 13754 | |
| 13755 | When using a @acronym{UDP} connection for remote debugging, you should |
| 13756 | keep in mind that the `U' stands for ``Unreliable''. @acronym{UDP} |
| 13757 | can silently drop packets on busy or unreliable networks, which will |
| 13758 | cause havoc with your debugging session. |
| 13759 | |
| 13760 | @item target remote | @var{command} |
| 13761 | @cindex pipe, @code{target remote} to |
| 13762 | Run @var{command} in the background and communicate with it using a |
| 13763 | pipe. The @var{command} is a shell command, to be parsed and expanded |
| 13764 | by the system's command shell, @code{/bin/sh}; it should expect remote |
| 13765 | protocol packets on its standard input, and send replies on its |
| 13766 | standard output. You could use this to run a stand-alone simulator |
| 13767 | that speaks the remote debugging protocol, to make net connections |
| 13768 | using programs like @code{ssh}, or for other similar tricks. |
| 13769 | |
| 13770 | If @var{command} closes its standard output (perhaps by exiting), |
| 13771 | @value{GDBN} will try to send it a @code{SIGTERM} signal. (If the |
| 13772 | program has already exited, this will have no effect.) |
| 13773 | |
| 13774 | @end table |
| 13775 | |
| 13776 | Once the connection has been established, you can use all the usual |
| 13777 | commands to examine and change data. The remote program is already |
| 13778 | running; you can use @kbd{step} and @kbd{continue}, and you do not |
| 13779 | need to use @kbd{run}. |
| 13780 | |
| 13781 | @cindex interrupting remote programs |
| 13782 | @cindex remote programs, interrupting |
| 13783 | Whenever @value{GDBN} is waiting for the remote program, if you type the |
| 13784 | interrupt character (often @kbd{Ctrl-c}), @value{GDBN} attempts to stop the |
| 13785 | program. This may or may not succeed, depending in part on the hardware |
| 13786 | and the serial drivers the remote system uses. If you type the |
| 13787 | interrupt character once again, @value{GDBN} displays this prompt: |
| 13788 | |
| 13789 | @smallexample |
| 13790 | Interrupted while waiting for the program. |
| 13791 | Give up (and stop debugging it)? (y or n) |
| 13792 | @end smallexample |
| 13793 | |
| 13794 | If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. |
| 13795 | (If you decide you want to try again later, you can use @samp{target |
| 13796 | remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} |
| 13797 | goes back to waiting. |
| 13798 | |
| 13799 | @table @code |
| 13800 | @kindex detach (remote) |
| 13801 | @item detach |
| 13802 | When you have finished debugging the remote program, you can use the |
| 13803 | @code{detach} command to release it from @value{GDBN} control. |
| 13804 | Detaching from the target normally resumes its execution, but the results |
| 13805 | will depend on your particular remote stub. After the @code{detach} |
| 13806 | command, @value{GDBN} is free to connect to another target. |
| 13807 | |
| 13808 | @kindex disconnect |
| 13809 | @item disconnect |
| 13810 | The @code{disconnect} command behaves like @code{detach}, except that |
| 13811 | the target is generally not resumed. It will wait for @value{GDBN} |
| 13812 | (this instance or another one) to connect and continue debugging. After |
| 13813 | the @code{disconnect} command, @value{GDBN} is again free to connect to |
| 13814 | another target. |
| 13815 | |
| 13816 | @cindex send command to remote monitor |
| 13817 | @cindex extend @value{GDBN} for remote targets |
| 13818 | @cindex add new commands for external monitor |
| 13819 | @kindex monitor |
| 13820 | @item monitor @var{cmd} |
| 13821 | This command allows you to send arbitrary commands directly to the |
| 13822 | remote monitor. Since @value{GDBN} doesn't care about the commands it |
| 13823 | sends like this, this command is the way to extend @value{GDBN}---you |
| 13824 | can add new commands that only the external monitor will understand |
| 13825 | and implement. |
| 13826 | @end table |
| 13827 | |
| 13828 | @node File Transfer |
| 13829 | @section Sending files to a remote system |
| 13830 | @cindex remote target, file transfer |
| 13831 | @cindex file transfer |
| 13832 | @cindex sending files to remote systems |
| 13833 | |
| 13834 | Some remote targets offer the ability to transfer files over the same |
| 13835 | connection used to communicate with @value{GDBN}. This is convenient |
| 13836 | for targets accessible through other means, e.g.@: @sc{gnu}/Linux systems |
| 13837 | running @code{gdbserver} over a network interface. For other targets, |
| 13838 | e.g.@: embedded devices with only a single serial port, this may be |
| 13839 | the only way to upload or download files. |
| 13840 | |
| 13841 | Not all remote targets support these commands. |
| 13842 | |
| 13843 | @table @code |
| 13844 | @kindex remote put |
| 13845 | @item remote put @var{hostfile} @var{targetfile} |
| 13846 | Copy file @var{hostfile} from the host system (the machine running |
| 13847 | @value{GDBN}) to @var{targetfile} on the target system. |
| 13848 | |
| 13849 | @kindex remote get |
| 13850 | @item remote get @var{targetfile} @var{hostfile} |
| 13851 | Copy file @var{targetfile} from the target system to @var{hostfile} |
| 13852 | on the host system. |
| 13853 | |
| 13854 | @kindex remote delete |
| 13855 | @item remote delete @var{targetfile} |
| 13856 | Delete @var{targetfile} from the target system. |
| 13857 | |
| 13858 | @end table |
| 13859 | |
| 13860 | @node Server |
| 13861 | @section Using the @code{gdbserver} Program |
| 13862 | |
| 13863 | @kindex gdbserver |
| 13864 | @cindex remote connection without stubs |
| 13865 | @code{gdbserver} is a control program for Unix-like systems, which |
| 13866 | allows you to connect your program with a remote @value{GDBN} via |
| 13867 | @code{target remote}---but without linking in the usual debugging stub. |
| 13868 | |
| 13869 | @code{gdbserver} is not a complete replacement for the debugging stubs, |
| 13870 | because it requires essentially the same operating-system facilities |
| 13871 | that @value{GDBN} itself does. In fact, a system that can run |
| 13872 | @code{gdbserver} to connect to a remote @value{GDBN} could also run |
| 13873 | @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, |
| 13874 | because it is a much smaller program than @value{GDBN} itself. It is |
| 13875 | also easier to port than all of @value{GDBN}, so you may be able to get |
| 13876 | started more quickly on a new system by using @code{gdbserver}. |
| 13877 | Finally, if you develop code for real-time systems, you may find that |
| 13878 | the tradeoffs involved in real-time operation make it more convenient to |
| 13879 | do as much development work as possible on another system, for example |
| 13880 | by cross-compiling. You can use @code{gdbserver} to make a similar |
| 13881 | choice for debugging. |
| 13882 | |
| 13883 | @value{GDBN} and @code{gdbserver} communicate via either a serial line |
| 13884 | or a TCP connection, using the standard @value{GDBN} remote serial |
| 13885 | protocol. |
| 13886 | |
| 13887 | @quotation |
| 13888 | @emph{Warning:} @code{gdbserver} does not have any built-in security. |
| 13889 | Do not run @code{gdbserver} connected to any public network; a |
| 13890 | @value{GDBN} connection to @code{gdbserver} provides access to the |
| 13891 | target system with the same privileges as the user running |
| 13892 | @code{gdbserver}. |
| 13893 | @end quotation |
| 13894 | |
| 13895 | @subsection Running @code{gdbserver} |
| 13896 | @cindex arguments, to @code{gdbserver} |
| 13897 | |
| 13898 | Run @code{gdbserver} on the target system. You need a copy of the |
| 13899 | program you want to debug, including any libraries it requires. |
| 13900 | @code{gdbserver} does not need your program's symbol table, so you can |
| 13901 | strip the program if necessary to save space. @value{GDBN} on the host |
| 13902 | system does all the symbol handling. |
| 13903 | |
| 13904 | To use the server, you must tell it how to communicate with @value{GDBN}; |
| 13905 | the name of your program; and the arguments for your program. The usual |
| 13906 | syntax is: |
| 13907 | |
| 13908 | @smallexample |
| 13909 | target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] |
| 13910 | @end smallexample |
| 13911 | |
| 13912 | @var{comm} is either a device name (to use a serial line) or a TCP |
| 13913 | hostname and portnumber. For example, to debug Emacs with the argument |
| 13914 | @samp{foo.txt} and communicate with @value{GDBN} over the serial port |
| 13915 | @file{/dev/com1}: |
| 13916 | |
| 13917 | @smallexample |
| 13918 | target> gdbserver /dev/com1 emacs foo.txt |
| 13919 | @end smallexample |
| 13920 | |
| 13921 | @code{gdbserver} waits passively for the host @value{GDBN} to communicate |
| 13922 | with it. |
| 13923 | |
| 13924 | To use a TCP connection instead of a serial line: |
| 13925 | |
| 13926 | @smallexample |
| 13927 | target> gdbserver host:2345 emacs foo.txt |
| 13928 | @end smallexample |
| 13929 | |
| 13930 | The only difference from the previous example is the first argument, |
| 13931 | specifying that you are communicating with the host @value{GDBN} via |
| 13932 | TCP. The @samp{host:2345} argument means that @code{gdbserver} is to |
| 13933 | expect a TCP connection from machine @samp{host} to local TCP port 2345. |
| 13934 | (Currently, the @samp{host} part is ignored.) You can choose any number |
| 13935 | you want for the port number as long as it does not conflict with any |
| 13936 | TCP ports already in use on the target system (for example, @code{23} is |
| 13937 | reserved for @code{telnet}).@footnote{If you choose a port number that |
| 13938 | conflicts with another service, @code{gdbserver} prints an error message |
| 13939 | and exits.} You must use the same port number with the host @value{GDBN} |
| 13940 | @code{target remote} command. |
| 13941 | |
| 13942 | @subsubsection Attaching to a Running Program |
| 13943 | |
| 13944 | On some targets, @code{gdbserver} can also attach to running programs. |
| 13945 | This is accomplished via the @code{--attach} argument. The syntax is: |
| 13946 | |
| 13947 | @smallexample |
| 13948 | target> gdbserver --attach @var{comm} @var{pid} |
| 13949 | @end smallexample |
| 13950 | |
| 13951 | @var{pid} is the process ID of a currently running process. It isn't necessary |
| 13952 | to point @code{gdbserver} at a binary for the running process. |
| 13953 | |
| 13954 | @pindex pidof |
| 13955 | @cindex attach to a program by name |
| 13956 | You can debug processes by name instead of process ID if your target has the |
| 13957 | @code{pidof} utility: |
| 13958 | |
| 13959 | @smallexample |
| 13960 | target> gdbserver --attach @var{comm} `pidof @var{program}` |
| 13961 | @end smallexample |
| 13962 | |
| 13963 | In case more than one copy of @var{program} is running, or @var{program} |
| 13964 | has multiple threads, most versions of @code{pidof} support the |
| 13965 | @code{-s} option to only return the first process ID. |
| 13966 | |
| 13967 | @subsubsection Multi-Process Mode for @code{gdbserver} |
| 13968 | @cindex gdbserver, multiple processes |
| 13969 | @cindex multiple processes with gdbserver |
| 13970 | |
| 13971 | When you connect to @code{gdbserver} using @code{target remote}, |
| 13972 | @code{gdbserver} debugs the specified program only once. When the |
| 13973 | program exits, or you detach from it, @value{GDBN} closes the connection |
| 13974 | and @code{gdbserver} exits. |
| 13975 | |
| 13976 | If you connect using @kbd{target extended-remote}, @code{gdbserver} |
| 13977 | enters multi-process mode. When the debugged program exits, or you |
| 13978 | detach from it, @value{GDBN} stays connected to @code{gdbserver} even |
| 13979 | though no program is running. The @code{run} and @code{attach} |
| 13980 | commands instruct @code{gdbserver} to run or attach to a new program. |
| 13981 | The @code{run} command uses @code{set remote exec-file} (@pxref{set |
| 13982 | remote exec-file}) to select the program to run. Command line |
| 13983 | arguments are supported, except for wildcard expansion and I/O |
| 13984 | redirection (@pxref{Arguments}). |
| 13985 | |
| 13986 | To start @code{gdbserver} without supplying an initial command to run |
| 13987 | or process ID to attach, use the @option{--multi} command line option. |
| 13988 | Then you can connect using @kbd{target extended-remote} and start |
| 13989 | the program you want to debug. |
| 13990 | |
| 13991 | @code{gdbserver} does not automatically exit in multi-process mode. |
| 13992 | You can terminate it by using @code{monitor exit} |
| 13993 | (@pxref{Monitor Commands for gdbserver}). |
| 13994 | |
| 13995 | @subsubsection Other Command-Line Arguments for @code{gdbserver} |
| 13996 | |
| 13997 | The @option{--debug} option tells @code{gdbserver} to display extra |
| 13998 | status information about the debugging process. The |
| 13999 | @option{--remote-debug} option tells @code{gdbserver} to display |
| 14000 | remote protocol debug output. These options are intended for |
| 14001 | @code{gdbserver} development and for bug reports to the developers. |
| 14002 | |
| 14003 | The @option{--wrapper} option specifies a wrapper to launch programs |
| 14004 | for debugging. The option should be followed by the name of the |
| 14005 | wrapper, then any command-line arguments to pass to the wrapper, then |
| 14006 | @kbd{--} indicating the end of the wrapper arguments. |
| 14007 | |
| 14008 | @code{gdbserver} runs the specified wrapper program with a combined |
| 14009 | command line including the wrapper arguments, then the name of the |
| 14010 | program to debug, then any arguments to the program. The wrapper |
| 14011 | runs until it executes your program, and then @value{GDBN} gains control. |
| 14012 | |
| 14013 | You can use any program that eventually calls @code{execve} with |
| 14014 | its arguments as a wrapper. Several standard Unix utilities do |
| 14015 | this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending |
| 14016 | with @code{exec "$@@"} will also work. |
| 14017 | |
| 14018 | For example, you can use @code{env} to pass an environment variable to |
| 14019 | the debugged program, without setting the variable in @code{gdbserver}'s |
| 14020 | environment: |
| 14021 | |
| 14022 | @smallexample |
| 14023 | $ gdbserver --wrapper env LD_PRELOAD=libtest.so -- :2222 ./testprog |
| 14024 | @end smallexample |
| 14025 | |
| 14026 | @subsection Connecting to @code{gdbserver} |
| 14027 | |
| 14028 | Run @value{GDBN} on the host system. |
| 14029 | |
| 14030 | First make sure you have the necessary symbol files. Load symbols for |
| 14031 | your application using the @code{file} command before you connect. Use |
| 14032 | @code{set sysroot} to locate target libraries (unless your @value{GDBN} |
| 14033 | was compiled with the correct sysroot using @code{--with-sysroot}). |
| 14034 | |
| 14035 | The symbol file and target libraries must exactly match the executable |
| 14036 | and libraries on the target, with one exception: the files on the host |
| 14037 | system should not be stripped, even if the files on the target system |
| 14038 | are. Mismatched or missing files will lead to confusing results |
| 14039 | during debugging. On @sc{gnu}/Linux targets, mismatched or missing |
| 14040 | files may also prevent @code{gdbserver} from debugging multi-threaded |
| 14041 | programs. |
| 14042 | |
| 14043 | Connect to your target (@pxref{Connecting,,Connecting to a Remote Target}). |
| 14044 | For TCP connections, you must start up @code{gdbserver} prior to using |
| 14045 | the @code{target remote} command. Otherwise you may get an error whose |
| 14046 | text depends on the host system, but which usually looks something like |
| 14047 | @samp{Connection refused}. Don't use the @code{load} |
| 14048 | command in @value{GDBN} when using @code{gdbserver}, since the program is |
| 14049 | already on the target. |
| 14050 | |
| 14051 | @subsection Monitor Commands for @code{gdbserver} |
| 14052 | @cindex monitor commands, for @code{gdbserver} |
| 14053 | @anchor{Monitor Commands for gdbserver} |
| 14054 | |
| 14055 | During a @value{GDBN} session using @code{gdbserver}, you can use the |
| 14056 | @code{monitor} command to send special requests to @code{gdbserver}. |
| 14057 | Here are the available commands. |
| 14058 | |
| 14059 | @table @code |
| 14060 | @item monitor help |
| 14061 | List the available monitor commands. |
| 14062 | |
| 14063 | @item monitor set debug 0 |
| 14064 | @itemx monitor set debug 1 |
| 14065 | Disable or enable general debugging messages. |
| 14066 | |
| 14067 | @item monitor set remote-debug 0 |
| 14068 | @itemx monitor set remote-debug 1 |
| 14069 | Disable or enable specific debugging messages associated with the remote |
| 14070 | protocol (@pxref{Remote Protocol}). |
| 14071 | |
| 14072 | @item monitor exit |
| 14073 | Tell gdbserver to exit immediately. This command should be followed by |
| 14074 | @code{disconnect} to close the debugging session. @code{gdbserver} will |
| 14075 | detach from any attached processes and kill any processes it created. |
| 14076 | Use @code{monitor exit} to terminate @code{gdbserver} at the end |
| 14077 | of a multi-process mode debug session. |
| 14078 | |
| 14079 | @end table |
| 14080 | |
| 14081 | @node Remote Configuration |
| 14082 | @section Remote Configuration |
| 14083 | |
| 14084 | @kindex set remote |
| 14085 | @kindex show remote |
| 14086 | This section documents the configuration options available when |
| 14087 | debugging remote programs. For the options related to the File I/O |
| 14088 | extensions of the remote protocol, see @ref{system, |
| 14089 | system-call-allowed}. |
| 14090 | |
| 14091 | @table @code |
| 14092 | @item set remoteaddresssize @var{bits} |
| 14093 | @cindex address size for remote targets |
| 14094 | @cindex bits in remote address |
| 14095 | Set the maximum size of address in a memory packet to the specified |
| 14096 | number of bits. @value{GDBN} will mask off the address bits above |
| 14097 | that number, when it passes addresses to the remote target. The |
| 14098 | default value is the number of bits in the target's address. |
| 14099 | |
| 14100 | @item show remoteaddresssize |
| 14101 | Show the current value of remote address size in bits. |
| 14102 | |
| 14103 | @item set remotebaud @var{n} |
| 14104 | @cindex baud rate for remote targets |
| 14105 | Set the baud rate for the remote serial I/O to @var{n} baud. The |
| 14106 | value is used to set the speed of the serial port used for debugging |
| 14107 | remote targets. |
| 14108 | |
| 14109 | @item show remotebaud |
| 14110 | Show the current speed of the remote connection. |
| 14111 | |
| 14112 | @item set remotebreak |
| 14113 | @cindex interrupt remote programs |
| 14114 | @cindex BREAK signal instead of Ctrl-C |
| 14115 | @anchor{set remotebreak} |
| 14116 | If set to on, @value{GDBN} sends a @code{BREAK} signal to the remote |
| 14117 | when you type @kbd{Ctrl-c} to interrupt the program running |
| 14118 | on the remote. If set to off, @value{GDBN} sends the @samp{Ctrl-C} |
| 14119 | character instead. The default is off, since most remote systems |
| 14120 | expect to see @samp{Ctrl-C} as the interrupt signal. |
| 14121 | |
| 14122 | @item show remotebreak |
| 14123 | Show whether @value{GDBN} sends @code{BREAK} or @samp{Ctrl-C} to |
| 14124 | interrupt the remote program. |
| 14125 | |
| 14126 | @item set remoteflow on |
| 14127 | @itemx set remoteflow off |
| 14128 | @kindex set remoteflow |
| 14129 | Enable or disable hardware flow control (@code{RTS}/@code{CTS}) |
| 14130 | on the serial port used to communicate to the remote target. |
| 14131 | |
| 14132 | @item show remoteflow |
| 14133 | @kindex show remoteflow |
| 14134 | Show the current setting of hardware flow control. |
| 14135 | |
| 14136 | @item set remotelogbase @var{base} |
| 14137 | Set the base (a.k.a.@: radix) of logging serial protocol |
| 14138 | communications to @var{base}. Supported values of @var{base} are: |
| 14139 | @code{ascii}, @code{octal}, and @code{hex}. The default is |
| 14140 | @code{ascii}. |
| 14141 | |
| 14142 | @item show remotelogbase |
| 14143 | Show the current setting of the radix for logging remote serial |
| 14144 | protocol. |
| 14145 | |
| 14146 | @item set remotelogfile @var{file} |
| 14147 | @cindex record serial communications on file |
| 14148 | Record remote serial communications on the named @var{file}. The |
| 14149 | default is not to record at all. |
| 14150 | |
| 14151 | @item show remotelogfile. |
| 14152 | Show the current setting of the file name on which to record the |
| 14153 | serial communications. |
| 14154 | |
| 14155 | @item set remotetimeout @var{num} |
| 14156 | @cindex timeout for serial communications |
| 14157 | @cindex remote timeout |
| 14158 | Set the timeout limit to wait for the remote target to respond to |
| 14159 | @var{num} seconds. The default is 2 seconds. |
| 14160 | |
| 14161 | @item show remotetimeout |
| 14162 | Show the current number of seconds to wait for the remote target |
| 14163 | responses. |
| 14164 | |
| 14165 | @cindex limit hardware breakpoints and watchpoints |
| 14166 | @cindex remote target, limit break- and watchpoints |
| 14167 | @anchor{set remote hardware-watchpoint-limit} |
| 14168 | @anchor{set remote hardware-breakpoint-limit} |
| 14169 | @item set remote hardware-watchpoint-limit @var{limit} |
| 14170 | @itemx set remote hardware-breakpoint-limit @var{limit} |
| 14171 | Restrict @value{GDBN} to using @var{limit} remote hardware breakpoint or |
| 14172 | watchpoints. A limit of -1, the default, is treated as unlimited. |
| 14173 | |
| 14174 | @item set remote exec-file @var{filename} |
| 14175 | @itemx show remote exec-file |
| 14176 | @anchor{set remote exec-file} |
| 14177 | @cindex executable file, for remote target |
| 14178 | Select the file used for @code{run} with @code{target |
| 14179 | extended-remote}. This should be set to a filename valid on the |
| 14180 | target system. If it is not set, the target will use a default |
| 14181 | filename (e.g.@: the last program run). |
| 14182 | |
| 14183 | @kindex set tcp |
| 14184 | @kindex show tcp |
| 14185 | @item set tcp auto-retry on |
| 14186 | @cindex auto-retry, for remote TCP target |
| 14187 | Enable auto-retry for remote TCP connections. This is useful if the remote |
| 14188 | debugging agent is launched in parallel with @value{GDBN}; there is a race |
| 14189 | condition because the agent may not become ready to accept the connection |
| 14190 | before @value{GDBN} attempts to connect. When auto-retry is |
| 14191 | enabled, if the initial attempt to connect fails, @value{GDBN} reattempts |
| 14192 | to establish the connection using the timeout specified by |
| 14193 | @code{set tcp connect-timeout}. |
| 14194 | |
| 14195 | @item set tcp auto-retry off |
| 14196 | Do not auto-retry failed TCP connections. |
| 14197 | |
| 14198 | @item show tcp auto-retry |
| 14199 | Show the current auto-retry setting. |
| 14200 | |
| 14201 | @item set tcp connect-timeout @var{seconds} |
| 14202 | @cindex connection timeout, for remote TCP target |
| 14203 | @cindex timeout, for remote target connection |
| 14204 | Set the timeout for establishing a TCP connection to the remote target to |
| 14205 | @var{seconds}. The timeout affects both polling to retry failed connections |
| 14206 | (enabled by @code{set tcp auto-retry on}) and waiting for connections |
| 14207 | that are merely slow to complete, and represents an approximate cumulative |
| 14208 | value. |
| 14209 | |
| 14210 | @item show tcp connect-timeout |
| 14211 | Show the current connection timeout setting. |
| 14212 | @end table |
| 14213 | |
| 14214 | @cindex remote packets, enabling and disabling |
| 14215 | The @value{GDBN} remote protocol autodetects the packets supported by |
| 14216 | your debugging stub. If you need to override the autodetection, you |
| 14217 | can use these commands to enable or disable individual packets. Each |
| 14218 | packet can be set to @samp{on} (the remote target supports this |
| 14219 | packet), @samp{off} (the remote target does not support this packet), |
| 14220 | or @samp{auto} (detect remote target support for this packet). They |
| 14221 | all default to @samp{auto}. For more information about each packet, |
| 14222 | see @ref{Remote Protocol}. |
| 14223 | |
| 14224 | During normal use, you should not have to use any of these commands. |
| 14225 | If you do, that may be a bug in your remote debugging stub, or a bug |
| 14226 | in @value{GDBN}. You may want to report the problem to the |
| 14227 | @value{GDBN} developers. |
| 14228 | |
| 14229 | For each packet @var{name}, the command to enable or disable the |
| 14230 | packet is @code{set remote @var{name}-packet}. The available settings |
| 14231 | are: |
| 14232 | |
| 14233 | @multitable @columnfractions 0.28 0.32 0.25 |
| 14234 | @item Command Name |
| 14235 | @tab Remote Packet |
| 14236 | @tab Related Features |
| 14237 | |
| 14238 | @item @code{fetch-register} |
| 14239 | @tab @code{p} |
| 14240 | @tab @code{info registers} |
| 14241 | |
| 14242 | @item @code{set-register} |
| 14243 | @tab @code{P} |
| 14244 | @tab @code{set} |
| 14245 | |
| 14246 | @item @code{binary-download} |
| 14247 | @tab @code{X} |
| 14248 | @tab @code{load}, @code{set} |
| 14249 | |
| 14250 | @item @code{read-aux-vector} |
| 14251 | @tab @code{qXfer:auxv:read} |
| 14252 | @tab @code{info auxv} |
| 14253 | |
| 14254 | @item @code{symbol-lookup} |
| 14255 | @tab @code{qSymbol} |
| 14256 | @tab Detecting multiple threads |
| 14257 | |
| 14258 | @item @code{attach} |
| 14259 | @tab @code{vAttach} |
| 14260 | @tab @code{attach} |
| 14261 | |
| 14262 | @item @code{verbose-resume} |
| 14263 | @tab @code{vCont} |
| 14264 | @tab Stepping or resuming multiple threads |
| 14265 | |
| 14266 | @item @code{run} |
| 14267 | @tab @code{vRun} |
| 14268 | @tab @code{run} |
| 14269 | |
| 14270 | @item @code{software-breakpoint} |
| 14271 | @tab @code{Z0} |
| 14272 | @tab @code{break} |
| 14273 | |
| 14274 | @item @code{hardware-breakpoint} |
| 14275 | @tab @code{Z1} |
| 14276 | @tab @code{hbreak} |
| 14277 | |
| 14278 | @item @code{write-watchpoint} |
| 14279 | @tab @code{Z2} |
| 14280 | @tab @code{watch} |
| 14281 | |
| 14282 | @item @code{read-watchpoint} |
| 14283 | @tab @code{Z3} |
| 14284 | @tab @code{rwatch} |
| 14285 | |
| 14286 | @item @code{access-watchpoint} |
| 14287 | @tab @code{Z4} |
| 14288 | @tab @code{awatch} |
| 14289 | |
| 14290 | @item @code{target-features} |
| 14291 | @tab @code{qXfer:features:read} |
| 14292 | @tab @code{set architecture} |
| 14293 | |
| 14294 | @item @code{library-info} |
| 14295 | @tab @code{qXfer:libraries:read} |
| 14296 | @tab @code{info sharedlibrary} |
| 14297 | |
| 14298 | @item @code{memory-map} |
| 14299 | @tab @code{qXfer:memory-map:read} |
| 14300 | @tab @code{info mem} |
| 14301 | |
| 14302 | @item @code{read-spu-object} |
| 14303 | @tab @code{qXfer:spu:read} |
| 14304 | @tab @code{info spu} |
| 14305 | |
| 14306 | @item @code{write-spu-object} |
| 14307 | @tab @code{qXfer:spu:write} |
| 14308 | @tab @code{info spu} |
| 14309 | |
| 14310 | @item @code{get-thread-local-@*storage-address} |
| 14311 | @tab @code{qGetTLSAddr} |
| 14312 | @tab Displaying @code{__thread} variables |
| 14313 | |
| 14314 | @item @code{search-memory} |
| 14315 | @tab @code{qSearch:memory} |
| 14316 | @tab @code{find} |
| 14317 | |
| 14318 | @item @code{supported-packets} |
| 14319 | @tab @code{qSupported} |
| 14320 | @tab Remote communications parameters |
| 14321 | |
| 14322 | @item @code{pass-signals} |
| 14323 | @tab @code{QPassSignals} |
| 14324 | @tab @code{handle @var{signal}} |
| 14325 | |
| 14326 | @item @code{hostio-close-packet} |
| 14327 | @tab @code{vFile:close} |
| 14328 | @tab @code{remote get}, @code{remote put} |
| 14329 | |
| 14330 | @item @code{hostio-open-packet} |
| 14331 | @tab @code{vFile:open} |
| 14332 | @tab @code{remote get}, @code{remote put} |
| 14333 | |
| 14334 | @item @code{hostio-pread-packet} |
| 14335 | @tab @code{vFile:pread} |
| 14336 | @tab @code{remote get}, @code{remote put} |
| 14337 | |
| 14338 | @item @code{hostio-pwrite-packet} |
| 14339 | @tab @code{vFile:pwrite} |
| 14340 | @tab @code{remote get}, @code{remote put} |
| 14341 | |
| 14342 | @item @code{hostio-unlink-packet} |
| 14343 | @tab @code{vFile:unlink} |
| 14344 | @tab @code{remote delete} |
| 14345 | |
| 14346 | @item @code{noack-packet} |
| 14347 | @tab @code{QStartNoAckMode} |
| 14348 | @tab Packet acknowledgment |
| 14349 | |
| 14350 | @item @code{osdata} |
| 14351 | @tab @code{qXfer:osdata:read} |
| 14352 | @tab @code{info os} |
| 14353 | @end multitable |
| 14354 | |
| 14355 | @node Remote Stub |
| 14356 | @section Implementing a Remote Stub |
| 14357 | |
| 14358 | @cindex debugging stub, example |
| 14359 | @cindex remote stub, example |
| 14360 | @cindex stub example, remote debugging |
| 14361 | The stub files provided with @value{GDBN} implement the target side of the |
| 14362 | communication protocol, and the @value{GDBN} side is implemented in the |
| 14363 | @value{GDBN} source file @file{remote.c}. Normally, you can simply allow |
| 14364 | these subroutines to communicate, and ignore the details. (If you're |
| 14365 | implementing your own stub file, you can still ignore the details: start |
| 14366 | with one of the existing stub files. @file{sparc-stub.c} is the best |
| 14367 | organized, and therefore the easiest to read.) |
| 14368 | |
| 14369 | @cindex remote serial debugging, overview |
| 14370 | To debug a program running on another machine (the debugging |
| 14371 | @dfn{target} machine), you must first arrange for all the usual |
| 14372 | prerequisites for the program to run by itself. For example, for a C |
| 14373 | program, you need: |
| 14374 | |
| 14375 | @enumerate |
| 14376 | @item |
| 14377 | A startup routine to set up the C runtime environment; these usually |
| 14378 | have a name like @file{crt0}. The startup routine may be supplied by |
| 14379 | your hardware supplier, or you may have to write your own. |
| 14380 | |
| 14381 | @item |
| 14382 | A C subroutine library to support your program's |
| 14383 | subroutine calls, notably managing input and output. |
| 14384 | |
| 14385 | @item |
| 14386 | A way of getting your program to the other machine---for example, a |
| 14387 | download program. These are often supplied by the hardware |
| 14388 | manufacturer, but you may have to write your own from hardware |
| 14389 | documentation. |
| 14390 | @end enumerate |
| 14391 | |
| 14392 | The next step is to arrange for your program to use a serial port to |
| 14393 | communicate with the machine where @value{GDBN} is running (the @dfn{host} |
| 14394 | machine). In general terms, the scheme looks like this: |
| 14395 | |
| 14396 | @table @emph |
| 14397 | @item On the host, |
| 14398 | @value{GDBN} already understands how to use this protocol; when everything |
| 14399 | else is set up, you can simply use the @samp{target remote} command |
| 14400 | (@pxref{Targets,,Specifying a Debugging Target}). |
| 14401 | |
| 14402 | @item On the target, |
| 14403 | you must link with your program a few special-purpose subroutines that |
| 14404 | implement the @value{GDBN} remote serial protocol. The file containing these |
| 14405 | subroutines is called a @dfn{debugging stub}. |
| 14406 | |
| 14407 | On certain remote targets, you can use an auxiliary program |
| 14408 | @code{gdbserver} instead of linking a stub into your program. |
| 14409 | @xref{Server,,Using the @code{gdbserver} Program}, for details. |
| 14410 | @end table |
| 14411 | |
| 14412 | The debugging stub is specific to the architecture of the remote |
| 14413 | machine; for example, use @file{sparc-stub.c} to debug programs on |
| 14414 | @sc{sparc} boards. |
| 14415 | |
| 14416 | @cindex remote serial stub list |
| 14417 | These working remote stubs are distributed with @value{GDBN}: |
| 14418 | |
| 14419 | @table @code |
| 14420 | |
| 14421 | @item i386-stub.c |
| 14422 | @cindex @file{i386-stub.c} |
| 14423 | @cindex Intel |
| 14424 | @cindex i386 |
| 14425 | For Intel 386 and compatible architectures. |
| 14426 | |
| 14427 | @item m68k-stub.c |
| 14428 | @cindex @file{m68k-stub.c} |
| 14429 | @cindex Motorola 680x0 |
| 14430 | @cindex m680x0 |
| 14431 | For Motorola 680x0 architectures. |
| 14432 | |
| 14433 | @item sh-stub.c |
| 14434 | @cindex @file{sh-stub.c} |
| 14435 | @cindex Renesas |
| 14436 | @cindex SH |
| 14437 | For Renesas SH architectures. |
| 14438 | |
| 14439 | @item sparc-stub.c |
| 14440 | @cindex @file{sparc-stub.c} |
| 14441 | @cindex Sparc |
| 14442 | For @sc{sparc} architectures. |
| 14443 | |
| 14444 | @item sparcl-stub.c |
| 14445 | @cindex @file{sparcl-stub.c} |
| 14446 | @cindex Fujitsu |
| 14447 | @cindex SparcLite |
| 14448 | For Fujitsu @sc{sparclite} architectures. |
| 14449 | |
| 14450 | @end table |
| 14451 | |
| 14452 | The @file{README} file in the @value{GDBN} distribution may list other |
| 14453 | recently added stubs. |
| 14454 | |
| 14455 | @menu |
| 14456 | * Stub Contents:: What the stub can do for you |
| 14457 | * Bootstrapping:: What you must do for the stub |
| 14458 | * Debug Session:: Putting it all together |
| 14459 | @end menu |
| 14460 | |
| 14461 | @node Stub Contents |
| 14462 | @subsection What the Stub Can Do for You |
| 14463 | |
| 14464 | @cindex remote serial stub |
| 14465 | The debugging stub for your architecture supplies these three |
| 14466 | subroutines: |
| 14467 | |
| 14468 | @table @code |
| 14469 | @item set_debug_traps |
| 14470 | @findex set_debug_traps |
| 14471 | @cindex remote serial stub, initialization |
| 14472 | This routine arranges for @code{handle_exception} to run when your |
| 14473 | program stops. You must call this subroutine explicitly near the |
| 14474 | beginning of your program. |
| 14475 | |
| 14476 | @item handle_exception |
| 14477 | @findex handle_exception |
| 14478 | @cindex remote serial stub, main routine |
| 14479 | This is the central workhorse, but your program never calls it |
| 14480 | explicitly---the setup code arranges for @code{handle_exception} to |
| 14481 | run when a trap is triggered. |
| 14482 | |
| 14483 | @code{handle_exception} takes control when your program stops during |
| 14484 | execution (for example, on a breakpoint), and mediates communications |
| 14485 | with @value{GDBN} on the host machine. This is where the communications |
| 14486 | protocol is implemented; @code{handle_exception} acts as the @value{GDBN} |
| 14487 | representative on the target machine. It begins by sending summary |
| 14488 | information on the state of your program, then continues to execute, |
| 14489 | retrieving and transmitting any information @value{GDBN} needs, until you |
| 14490 | execute a @value{GDBN} command that makes your program resume; at that point, |
| 14491 | @code{handle_exception} returns control to your own code on the target |
| 14492 | machine. |
| 14493 | |
| 14494 | @item breakpoint |
| 14495 | @cindex @code{breakpoint} subroutine, remote |
| 14496 | Use this auxiliary subroutine to make your program contain a |
| 14497 | breakpoint. Depending on the particular situation, this may be the only |
| 14498 | way for @value{GDBN} to get control. For instance, if your target |
| 14499 | machine has some sort of interrupt button, you won't need to call this; |
| 14500 | pressing the interrupt button transfers control to |
| 14501 | @code{handle_exception}---in effect, to @value{GDBN}. On some machines, |
| 14502 | simply receiving characters on the serial port may also trigger a trap; |
| 14503 | again, in that situation, you don't need to call @code{breakpoint} from |
| 14504 | your own program---simply running @samp{target remote} from the host |
| 14505 | @value{GDBN} session gets control. |
| 14506 | |
| 14507 | Call @code{breakpoint} if none of these is true, or if you simply want |
| 14508 | to make certain your program stops at a predetermined point for the |
| 14509 | start of your debugging session. |
| 14510 | @end table |
| 14511 | |
| 14512 | @node Bootstrapping |
| 14513 | @subsection What You Must Do for the Stub |
| 14514 | |
| 14515 | @cindex remote stub, support routines |
| 14516 | The debugging stubs that come with @value{GDBN} are set up for a particular |
| 14517 | chip architecture, but they have no information about the rest of your |
| 14518 | debugging target machine. |
| 14519 | |
| 14520 | First of all you need to tell the stub how to communicate with the |
| 14521 | serial port. |
| 14522 | |
| 14523 | @table @code |
| 14524 | @item int getDebugChar() |
| 14525 | @findex getDebugChar |
| 14526 | Write this subroutine to read a single character from the serial port. |
| 14527 | It may be identical to @code{getchar} for your target system; a |
| 14528 | different name is used to allow you to distinguish the two if you wish. |
| 14529 | |
| 14530 | @item void putDebugChar(int) |
| 14531 | @findex putDebugChar |
| 14532 | Write this subroutine to write a single character to the serial port. |
| 14533 | It may be identical to @code{putchar} for your target system; a |
| 14534 | different name is used to allow you to distinguish the two if you wish. |
| 14535 | @end table |
| 14536 | |
| 14537 | @cindex control C, and remote debugging |
| 14538 | @cindex interrupting remote targets |
| 14539 | If you want @value{GDBN} to be able to stop your program while it is |
| 14540 | running, you need to use an interrupt-driven serial driver, and arrange |
| 14541 | for it to stop when it receives a @code{^C} (@samp{\003}, the control-C |
| 14542 | character). That is the character which @value{GDBN} uses to tell the |
| 14543 | remote system to stop. |
| 14544 | |
| 14545 | Getting the debugging target to return the proper status to @value{GDBN} |
| 14546 | probably requires changes to the standard stub; one quick and dirty way |
| 14547 | is to just execute a breakpoint instruction (the ``dirty'' part is that |
| 14548 | @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). |
| 14549 | |
| 14550 | Other routines you need to supply are: |
| 14551 | |
| 14552 | @table @code |
| 14553 | @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) |
| 14554 | @findex exceptionHandler |
| 14555 | Write this function to install @var{exception_address} in the exception |
| 14556 | handling tables. You need to do this because the stub does not have any |
| 14557 | way of knowing what the exception handling tables on your target system |
| 14558 | are like (for example, the processor's table might be in @sc{rom}, |
| 14559 | containing entries which point to a table in @sc{ram}). |
| 14560 | @var{exception_number} is the exception number which should be changed; |
| 14561 | its meaning is architecture-dependent (for example, different numbers |
| 14562 | might represent divide by zero, misaligned access, etc). When this |
| 14563 | exception occurs, control should be transferred directly to |
| 14564 | @var{exception_address}, and the processor state (stack, registers, |
| 14565 | and so on) should be just as it is when a processor exception occurs. So if |
| 14566 | you want to use a jump instruction to reach @var{exception_address}, it |
| 14567 | should be a simple jump, not a jump to subroutine. |
| 14568 | |
| 14569 | For the 386, @var{exception_address} should be installed as an interrupt |
| 14570 | gate so that interrupts are masked while the handler runs. The gate |
| 14571 | should be at privilege level 0 (the most privileged level). The |
| 14572 | @sc{sparc} and 68k stubs are able to mask interrupts themselves without |
| 14573 | help from @code{exceptionHandler}. |
| 14574 | |
| 14575 | @item void flush_i_cache() |
| 14576 | @findex flush_i_cache |
| 14577 | On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the |
| 14578 | instruction cache, if any, on your target machine. If there is no |
| 14579 | instruction cache, this subroutine may be a no-op. |
| 14580 | |
| 14581 | On target machines that have instruction caches, @value{GDBN} requires this |
| 14582 | function to make certain that the state of your program is stable. |
| 14583 | @end table |
| 14584 | |
| 14585 | @noindent |
| 14586 | You must also make sure this library routine is available: |
| 14587 | |
| 14588 | @table @code |
| 14589 | @item void *memset(void *, int, int) |
| 14590 | @findex memset |
| 14591 | This is the standard library function @code{memset} that sets an area of |
| 14592 | memory to a known value. If you have one of the free versions of |
| 14593 | @code{libc.a}, @code{memset} can be found there; otherwise, you must |
| 14594 | either obtain it from your hardware manufacturer, or write your own. |
| 14595 | @end table |
| 14596 | |
| 14597 | If you do not use the GNU C compiler, you may need other standard |
| 14598 | library subroutines as well; this varies from one stub to another, |
| 14599 | but in general the stubs are likely to use any of the common library |
| 14600 | subroutines which @code{@value{NGCC}} generates as inline code. |
| 14601 | |
| 14602 | |
| 14603 | @node Debug Session |
| 14604 | @subsection Putting it All Together |
| 14605 | |
| 14606 | @cindex remote serial debugging summary |
| 14607 | In summary, when your program is ready to debug, you must follow these |
| 14608 | steps. |
| 14609 | |
| 14610 | @enumerate |
| 14611 | @item |
| 14612 | Make sure you have defined the supporting low-level routines |
| 14613 | (@pxref{Bootstrapping,,What You Must Do for the Stub}): |
| 14614 | @display |
| 14615 | @code{getDebugChar}, @code{putDebugChar}, |
| 14616 | @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. |
| 14617 | @end display |
| 14618 | |
| 14619 | @item |
| 14620 | Insert these lines near the top of your program: |
| 14621 | |
| 14622 | @smallexample |
| 14623 | set_debug_traps(); |
| 14624 | breakpoint(); |
| 14625 | @end smallexample |
| 14626 | |
| 14627 | @item |
| 14628 | For the 680x0 stub only, you need to provide a variable called |
| 14629 | @code{exceptionHook}. Normally you just use: |
| 14630 | |
| 14631 | @smallexample |
| 14632 | void (*exceptionHook)() = 0; |
| 14633 | @end smallexample |
| 14634 | |
| 14635 | @noindent |
| 14636 | but if before calling @code{set_debug_traps}, you set it to point to a |
| 14637 | function in your program, that function is called when |
| 14638 | @code{@value{GDBN}} continues after stopping on a trap (for example, bus |
| 14639 | error). The function indicated by @code{exceptionHook} is called with |
| 14640 | one parameter: an @code{int} which is the exception number. |
| 14641 | |
| 14642 | @item |
| 14643 | Compile and link together: your program, the @value{GDBN} debugging stub for |
| 14644 | your target architecture, and the supporting subroutines. |
| 14645 | |
| 14646 | @item |
| 14647 | Make sure you have a serial connection between your target machine and |
| 14648 | the @value{GDBN} host, and identify the serial port on the host. |
| 14649 | |
| 14650 | @item |
| 14651 | @c The "remote" target now provides a `load' command, so we should |
| 14652 | @c document that. FIXME. |
| 14653 | Download your program to your target machine (or get it there by |
| 14654 | whatever means the manufacturer provides), and start it. |
| 14655 | |
| 14656 | @item |
| 14657 | Start @value{GDBN} on the host, and connect to the target |
| 14658 | (@pxref{Connecting,,Connecting to a Remote Target}). |
| 14659 | |
| 14660 | @end enumerate |
| 14661 | |
| 14662 | @node Configurations |
| 14663 | @chapter Configuration-Specific Information |
| 14664 | |
| 14665 | While nearly all @value{GDBN} commands are available for all native and |
| 14666 | cross versions of the debugger, there are some exceptions. This chapter |
| 14667 | describes things that are only available in certain configurations. |
| 14668 | |
| 14669 | There are three major categories of configurations: native |
| 14670 | configurations, where the host and target are the same, embedded |
| 14671 | operating system configurations, which are usually the same for several |
| 14672 | different processor architectures, and bare embedded processors, which |
| 14673 | are quite different from each other. |
| 14674 | |
| 14675 | @menu |
| 14676 | * Native:: |
| 14677 | * Embedded OS:: |
| 14678 | * Embedded Processors:: |
| 14679 | * Architectures:: |
| 14680 | @end menu |
| 14681 | |
| 14682 | @node Native |
| 14683 | @section Native |
| 14684 | |
| 14685 | This section describes details specific to particular native |
| 14686 | configurations. |
| 14687 | |
| 14688 | @menu |
| 14689 | * HP-UX:: HP-UX |
| 14690 | * BSD libkvm Interface:: Debugging BSD kernel memory images |
| 14691 | * SVR4 Process Information:: SVR4 process information |
| 14692 | * DJGPP Native:: Features specific to the DJGPP port |
| 14693 | * Cygwin Native:: Features specific to the Cygwin port |
| 14694 | * Hurd Native:: Features specific to @sc{gnu} Hurd |
| 14695 | * Neutrino:: Features specific to QNX Neutrino |
| 14696 | * Darwin:: Features specific to Darwin |
| 14697 | @end menu |
| 14698 | |
| 14699 | @node HP-UX |
| 14700 | @subsection HP-UX |
| 14701 | |
| 14702 | On HP-UX systems, if you refer to a function or variable name that |
| 14703 | begins with a dollar sign, @value{GDBN} searches for a user or system |
| 14704 | name first, before it searches for a convenience variable. |
| 14705 | |
| 14706 | |
| 14707 | @node BSD libkvm Interface |
| 14708 | @subsection BSD libkvm Interface |
| 14709 | |
| 14710 | @cindex libkvm |
| 14711 | @cindex kernel memory image |
| 14712 | @cindex kernel crash dump |
| 14713 | |
| 14714 | BSD-derived systems (FreeBSD/NetBSD/OpenBSD) have a kernel memory |
| 14715 | interface that provides a uniform interface for accessing kernel virtual |
| 14716 | memory images, including live systems and crash dumps. @value{GDBN} |
| 14717 | uses this interface to allow you to debug live kernels and kernel crash |
| 14718 | dumps on many native BSD configurations. This is implemented as a |
| 14719 | special @code{kvm} debugging target. For debugging a live system, load |
| 14720 | the currently running kernel into @value{GDBN} and connect to the |
| 14721 | @code{kvm} target: |
| 14722 | |
| 14723 | @smallexample |
| 14724 | (@value{GDBP}) @b{target kvm} |
| 14725 | @end smallexample |
| 14726 | |
| 14727 | For debugging crash dumps, provide the file name of the crash dump as an |
| 14728 | argument: |
| 14729 | |
| 14730 | @smallexample |
| 14731 | (@value{GDBP}) @b{target kvm /var/crash/bsd.0} |
| 14732 | @end smallexample |
| 14733 | |
| 14734 | Once connected to the @code{kvm} target, the following commands are |
| 14735 | available: |
| 14736 | |
| 14737 | @table @code |
| 14738 | @kindex kvm |
| 14739 | @item kvm pcb |
| 14740 | Set current context from the @dfn{Process Control Block} (PCB) address. |
| 14741 | |
| 14742 | @item kvm proc |
| 14743 | Set current context from proc address. This command isn't available on |
| 14744 | modern FreeBSD systems. |
| 14745 | @end table |
| 14746 | |
| 14747 | @node SVR4 Process Information |
| 14748 | @subsection SVR4 Process Information |
| 14749 | @cindex /proc |
| 14750 | @cindex examine process image |
| 14751 | @cindex process info via @file{/proc} |
| 14752 | |
| 14753 | Many versions of SVR4 and compatible systems provide a facility called |
| 14754 | @samp{/proc} that can be used to examine the image of a running |
| 14755 | process using file-system subroutines. If @value{GDBN} is configured |
| 14756 | for an operating system with this facility, the command @code{info |
| 14757 | proc} is available to report information about the process running |
| 14758 | your program, or about any process running on your system. @code{info |
| 14759 | proc} works only on SVR4 systems that include the @code{procfs} code. |
| 14760 | This includes, as of this writing, @sc{gnu}/Linux, OSF/1 (Digital |
| 14761 | Unix), Solaris, Irix, and Unixware, but not HP-UX, for example. |
| 14762 | |
| 14763 | @table @code |
| 14764 | @kindex info proc |
| 14765 | @cindex process ID |
| 14766 | @item info proc |
| 14767 | @itemx info proc @var{process-id} |
| 14768 | Summarize available information about any running process. If a |
| 14769 | process ID is specified by @var{process-id}, display information about |
| 14770 | that process; otherwise display information about the program being |
| 14771 | debugged. The summary includes the debugged process ID, the command |
| 14772 | line used to invoke it, its current working directory, and its |
| 14773 | executable file's absolute file name. |
| 14774 | |
| 14775 | On some systems, @var{process-id} can be of the form |
| 14776 | @samp{[@var{pid}]/@var{tid}} which specifies a certain thread ID |
| 14777 | within a process. If the optional @var{pid} part is missing, it means |
| 14778 | a thread from the process being debugged (the leading @samp{/} still |
| 14779 | needs to be present, or else @value{GDBN} will interpret the number as |
| 14780 | a process ID rather than a thread ID). |
| 14781 | |
| 14782 | @item info proc mappings |
| 14783 | @cindex memory address space mappings |
| 14784 | Report the memory address space ranges accessible in the program, with |
| 14785 | information on whether the process has read, write, or execute access |
| 14786 | rights to each range. On @sc{gnu}/Linux systems, each memory range |
| 14787 | includes the object file which is mapped to that range, instead of the |
| 14788 | memory access rights to that range. |
| 14789 | |
| 14790 | @item info proc stat |
| 14791 | @itemx info proc status |
| 14792 | @cindex process detailed status information |
| 14793 | These subcommands are specific to @sc{gnu}/Linux systems. They show |
| 14794 | the process-related information, including the user ID and group ID; |
| 14795 | how many threads are there in the process; its virtual memory usage; |
| 14796 | the signals that are pending, blocked, and ignored; its TTY; its |
| 14797 | consumption of system and user time; its stack size; its @samp{nice} |
| 14798 | value; etc. For more information, see the @samp{proc} man page |
| 14799 | (type @kbd{man 5 proc} from your shell prompt). |
| 14800 | |
| 14801 | @item info proc all |
| 14802 | Show all the information about the process described under all of the |
| 14803 | above @code{info proc} subcommands. |
| 14804 | |
| 14805 | @ignore |
| 14806 | @comment These sub-options of 'info proc' were not included when |
| 14807 | @comment procfs.c was re-written. Keep their descriptions around |
| 14808 | @comment against the day when someone finds the time to put them back in. |
| 14809 | @kindex info proc times |
| 14810 | @item info proc times |
| 14811 | Starting time, user CPU time, and system CPU time for your program and |
| 14812 | its children. |
| 14813 | |
| 14814 | @kindex info proc id |
| 14815 | @item info proc id |
| 14816 | Report on the process IDs related to your program: its own process ID, |
| 14817 | the ID of its parent, the process group ID, and the session ID. |
| 14818 | @end ignore |
| 14819 | |
| 14820 | @item set procfs-trace |
| 14821 | @kindex set procfs-trace |
| 14822 | @cindex @code{procfs} API calls |
| 14823 | This command enables and disables tracing of @code{procfs} API calls. |
| 14824 | |
| 14825 | @item show procfs-trace |
| 14826 | @kindex show procfs-trace |
| 14827 | Show the current state of @code{procfs} API call tracing. |
| 14828 | |
| 14829 | @item set procfs-file @var{file} |
| 14830 | @kindex set procfs-file |
| 14831 | Tell @value{GDBN} to write @code{procfs} API trace to the named |
| 14832 | @var{file}. @value{GDBN} appends the trace info to the previous |
| 14833 | contents of the file. The default is to display the trace on the |
| 14834 | standard output. |
| 14835 | |
| 14836 | @item show procfs-file |
| 14837 | @kindex show procfs-file |
| 14838 | Show the file to which @code{procfs} API trace is written. |
| 14839 | |
| 14840 | @item proc-trace-entry |
| 14841 | @itemx proc-trace-exit |
| 14842 | @itemx proc-untrace-entry |
| 14843 | @itemx proc-untrace-exit |
| 14844 | @kindex proc-trace-entry |
| 14845 | @kindex proc-trace-exit |
| 14846 | @kindex proc-untrace-entry |
| 14847 | @kindex proc-untrace-exit |
| 14848 | These commands enable and disable tracing of entries into and exits |
| 14849 | from the @code{syscall} interface. |
| 14850 | |
| 14851 | @item info pidlist |
| 14852 | @kindex info pidlist |
| 14853 | @cindex process list, QNX Neutrino |
| 14854 | For QNX Neutrino only, this command displays the list of all the |
| 14855 | processes and all the threads within each process. |
| 14856 | |
| 14857 | @item info meminfo |
| 14858 | @kindex info meminfo |
| 14859 | @cindex mapinfo list, QNX Neutrino |
| 14860 | For QNX Neutrino only, this command displays the list of all mapinfos. |
| 14861 | @end table |
| 14862 | |
| 14863 | @node DJGPP Native |
| 14864 | @subsection Features for Debugging @sc{djgpp} Programs |
| 14865 | @cindex @sc{djgpp} debugging |
| 14866 | @cindex native @sc{djgpp} debugging |
| 14867 | @cindex MS-DOS-specific commands |
| 14868 | |
| 14869 | @cindex DPMI |
| 14870 | @sc{djgpp} is a port of the @sc{gnu} development tools to MS-DOS and |
| 14871 | MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs |
| 14872 | that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on |
| 14873 | top of real-mode DOS systems and their emulations. |
| 14874 | |
| 14875 | @value{GDBN} supports native debugging of @sc{djgpp} programs, and |
| 14876 | defines a few commands specific to the @sc{djgpp} port. This |
| 14877 | subsection describes those commands. |
| 14878 | |
| 14879 | @table @code |
| 14880 | @kindex info dos |
| 14881 | @item info dos |
| 14882 | This is a prefix of @sc{djgpp}-specific commands which print |
| 14883 | information about the target system and important OS structures. |
| 14884 | |
| 14885 | @kindex sysinfo |
| 14886 | @cindex MS-DOS system info |
| 14887 | @cindex free memory information (MS-DOS) |
| 14888 | @item info dos sysinfo |
| 14889 | This command displays assorted information about the underlying |
| 14890 | platform: the CPU type and features, the OS version and flavor, the |
| 14891 | DPMI version, and the available conventional and DPMI memory. |
| 14892 | |
| 14893 | @cindex GDT |
| 14894 | @cindex LDT |
| 14895 | @cindex IDT |
| 14896 | @cindex segment descriptor tables |
| 14897 | @cindex descriptor tables display |
| 14898 | @item info dos gdt |
| 14899 | @itemx info dos ldt |
| 14900 | @itemx info dos idt |
| 14901 | These 3 commands display entries from, respectively, Global, Local, |
| 14902 | and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor |
| 14903 | tables are data structures which store a descriptor for each segment |
| 14904 | that is currently in use. The segment's selector is an index into a |
| 14905 | descriptor table; the table entry for that index holds the |
| 14906 | descriptor's base address and limit, and its attributes and access |
| 14907 | rights. |
| 14908 | |
| 14909 | A typical @sc{djgpp} program uses 3 segments: a code segment, a data |
| 14910 | segment (used for both data and the stack), and a DOS segment (which |
| 14911 | allows access to DOS/BIOS data structures and absolute addresses in |
| 14912 | conventional memory). However, the DPMI host will usually define |
| 14913 | additional segments in order to support the DPMI environment. |
| 14914 | |
| 14915 | @cindex garbled pointers |
| 14916 | These commands allow to display entries from the descriptor tables. |
| 14917 | Without an argument, all entries from the specified table are |
| 14918 | displayed. An argument, which should be an integer expression, means |
| 14919 | display a single entry whose index is given by the argument. For |
| 14920 | example, here's a convenient way to display information about the |
| 14921 | debugged program's data segment: |
| 14922 | |
| 14923 | @smallexample |
| 14924 | @exdent @code{(@value{GDBP}) info dos ldt $ds} |
| 14925 | @exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)} |
| 14926 | @end smallexample |
| 14927 | |
| 14928 | @noindent |
| 14929 | This comes in handy when you want to see whether a pointer is outside |
| 14930 | the data segment's limit (i.e.@: @dfn{garbled}). |
| 14931 | |
| 14932 | @cindex page tables display (MS-DOS) |
| 14933 | @item info dos pde |
| 14934 | @itemx info dos pte |
| 14935 | These two commands display entries from, respectively, the Page |
| 14936 | Directory and the Page Tables. Page Directories and Page Tables are |
| 14937 | data structures which control how virtual memory addresses are mapped |
| 14938 | into physical addresses. A Page Table includes an entry for every |
| 14939 | page of memory that is mapped into the program's address space; there |
| 14940 | may be several Page Tables, each one holding up to 4096 entries. A |
| 14941 | Page Directory has up to 4096 entries, one each for every Page Table |
| 14942 | that is currently in use. |
| 14943 | |
| 14944 | Without an argument, @kbd{info dos pde} displays the entire Page |
| 14945 | Directory, and @kbd{info dos pte} displays all the entries in all of |
| 14946 | the Page Tables. An argument, an integer expression, given to the |
| 14947 | @kbd{info dos pde} command means display only that entry from the Page |
| 14948 | Directory table. An argument given to the @kbd{info dos pte} command |
| 14949 | means display entries from a single Page Table, the one pointed to by |
| 14950 | the specified entry in the Page Directory. |
| 14951 | |
| 14952 | @cindex direct memory access (DMA) on MS-DOS |
| 14953 | These commands are useful when your program uses @dfn{DMA} (Direct |
| 14954 | Memory Access), which needs physical addresses to program the DMA |
| 14955 | controller. |
| 14956 | |
| 14957 | These commands are supported only with some DPMI servers. |
| 14958 | |
| 14959 | @cindex physical address from linear address |
| 14960 | @item info dos address-pte @var{addr} |
| 14961 | This command displays the Page Table entry for a specified linear |
| 14962 | address. The argument @var{addr} is a linear address which should |
| 14963 | already have the appropriate segment's base address added to it, |
| 14964 | because this command accepts addresses which may belong to @emph{any} |
| 14965 | segment. For example, here's how to display the Page Table entry for |
| 14966 | the page where a variable @code{i} is stored: |
| 14967 | |
| 14968 | @smallexample |
| 14969 | @exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i} |
| 14970 | @exdent @code{Page Table entry for address 0x11a00d30:} |
| 14971 | @exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30} |
| 14972 | @end smallexample |
| 14973 | |
| 14974 | @noindent |
| 14975 | This says that @code{i} is stored at offset @code{0xd30} from the page |
| 14976 | whose physical base address is @code{0x02698000}, and shows all the |
| 14977 | attributes of that page. |
| 14978 | |
| 14979 | Note that you must cast the addresses of variables to a @code{char *}, |
| 14980 | since otherwise the value of @code{__djgpp_base_address}, the base |
| 14981 | address of all variables and functions in a @sc{djgpp} program, will |
| 14982 | be added using the rules of C pointer arithmetics: if @code{i} is |
| 14983 | declared an @code{int}, @value{GDBN} will add 4 times the value of |
| 14984 | @code{__djgpp_base_address} to the address of @code{i}. |
| 14985 | |
| 14986 | Here's another example, it displays the Page Table entry for the |
| 14987 | transfer buffer: |
| 14988 | |
| 14989 | @smallexample |
| 14990 | @exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)} |
| 14991 | @exdent @code{Page Table entry for address 0x29110:} |
| 14992 | @exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110} |
| 14993 | @end smallexample |
| 14994 | |
| 14995 | @noindent |
| 14996 | (The @code{+ 3} offset is because the transfer buffer's address is the |
| 14997 | 3rd member of the @code{_go32_info_block} structure.) The output |
| 14998 | clearly shows that this DPMI server maps the addresses in conventional |
| 14999 | memory 1:1, i.e.@: the physical (@code{0x00029000} + @code{0x110}) and |
| 15000 | linear (@code{0x29110}) addresses are identical. |
| 15001 | |
| 15002 | This command is supported only with some DPMI servers. |
| 15003 | @end table |
| 15004 | |
| 15005 | @cindex DOS serial data link, remote debugging |
| 15006 | In addition to native debugging, the DJGPP port supports remote |
| 15007 | debugging via a serial data link. The following commands are specific |
| 15008 | to remote serial debugging in the DJGPP port of @value{GDBN}. |
| 15009 | |
| 15010 | @table @code |
| 15011 | @kindex set com1base |
| 15012 | @kindex set com1irq |
| 15013 | @kindex set com2base |
| 15014 | @kindex set com2irq |
| 15015 | @kindex set com3base |
| 15016 | @kindex set com3irq |
| 15017 | @kindex set com4base |
| 15018 | @kindex set com4irq |
| 15019 | @item set com1base @var{addr} |
| 15020 | This command sets the base I/O port address of the @file{COM1} serial |
| 15021 | port. |
| 15022 | |
| 15023 | @item set com1irq @var{irq} |
| 15024 | This command sets the @dfn{Interrupt Request} (@code{IRQ}) line to use |
| 15025 | for the @file{COM1} serial port. |
| 15026 | |
| 15027 | There are similar commands @samp{set com2base}, @samp{set com3irq}, |
| 15028 | etc.@: for setting the port address and the @code{IRQ} lines for the |
| 15029 | other 3 COM ports. |
| 15030 | |
| 15031 | @kindex show com1base |
| 15032 | @kindex show com1irq |
| 15033 | @kindex show com2base |
| 15034 | @kindex show com2irq |
| 15035 | @kindex show com3base |
| 15036 | @kindex show com3irq |
| 15037 | @kindex show com4base |
| 15038 | @kindex show com4irq |
| 15039 | The related commands @samp{show com1base}, @samp{show com1irq} etc.@: |
| 15040 | display the current settings of the base address and the @code{IRQ} |
| 15041 | lines used by the COM ports. |
| 15042 | |
| 15043 | @item info serial |
| 15044 | @kindex info serial |
| 15045 | @cindex DOS serial port status |
| 15046 | This command prints the status of the 4 DOS serial ports. For each |
| 15047 | port, it prints whether it's active or not, its I/O base address and |
| 15048 | IRQ number, whether it uses a 16550-style FIFO, its baudrate, and the |
| 15049 | counts of various errors encountered so far. |
| 15050 | @end table |
| 15051 | |
| 15052 | |
| 15053 | @node Cygwin Native |
| 15054 | @subsection Features for Debugging MS Windows PE Executables |
| 15055 | @cindex MS Windows debugging |
| 15056 | @cindex native Cygwin debugging |
| 15057 | @cindex Cygwin-specific commands |
| 15058 | |
| 15059 | @value{GDBN} supports native debugging of MS Windows programs, including |
| 15060 | DLLs with and without symbolic debugging information. There are various |
| 15061 | additional Cygwin-specific commands, described in this section. |
| 15062 | Working with DLLs that have no debugging symbols is described in |
| 15063 | @ref{Non-debug DLL Symbols}. |
| 15064 | |
| 15065 | @table @code |
| 15066 | @kindex info w32 |
| 15067 | @item info w32 |
| 15068 | This is a prefix of MS Windows-specific commands which print |
| 15069 | information about the target system and important OS structures. |
| 15070 | |
| 15071 | @item info w32 selector |
| 15072 | This command displays information returned by |
| 15073 | the Win32 API @code{GetThreadSelectorEntry} function. |
| 15074 | It takes an optional argument that is evaluated to |
| 15075 | a long value to give the information about this given selector. |
| 15076 | Without argument, this command displays information |
| 15077 | about the six segment registers. |
| 15078 | |
| 15079 | @kindex info dll |
| 15080 | @item info dll |
| 15081 | This is a Cygwin-specific alias of @code{info shared}. |
| 15082 | |
| 15083 | @kindex dll-symbols |
| 15084 | @item dll-symbols |
| 15085 | This command loads symbols from a dll similarly to |
| 15086 | add-sym command but without the need to specify a base address. |
| 15087 | |
| 15088 | @kindex set cygwin-exceptions |
| 15089 | @cindex debugging the Cygwin DLL |
| 15090 | @cindex Cygwin DLL, debugging |
| 15091 | @item set cygwin-exceptions @var{mode} |
| 15092 | If @var{mode} is @code{on}, @value{GDBN} will break on exceptions that |
| 15093 | happen inside the Cygwin DLL. If @var{mode} is @code{off}, |
| 15094 | @value{GDBN} will delay recognition of exceptions, and may ignore some |
| 15095 | exceptions which seem to be caused by internal Cygwin DLL |
| 15096 | ``bookkeeping''. This option is meant primarily for debugging the |
| 15097 | Cygwin DLL itself; the default value is @code{off} to avoid annoying |
| 15098 | @value{GDBN} users with false @code{SIGSEGV} signals. |
| 15099 | |
| 15100 | @kindex show cygwin-exceptions |
| 15101 | @item show cygwin-exceptions |
| 15102 | Displays whether @value{GDBN} will break on exceptions that happen |
| 15103 | inside the Cygwin DLL itself. |
| 15104 | |
| 15105 | @kindex set new-console |
| 15106 | @item set new-console @var{mode} |
| 15107 | If @var{mode} is @code{on} the debuggee will |
| 15108 | be started in a new console on next start. |
| 15109 | If @var{mode} is @code{off}i, the debuggee will |
| 15110 | be started in the same console as the debugger. |
| 15111 | |
| 15112 | @kindex show new-console |
| 15113 | @item show new-console |
| 15114 | Displays whether a new console is used |
| 15115 | when the debuggee is started. |
| 15116 | |
| 15117 | @kindex set new-group |
| 15118 | @item set new-group @var{mode} |
| 15119 | This boolean value controls whether the debuggee should |
| 15120 | start a new group or stay in the same group as the debugger. |
| 15121 | This affects the way the Windows OS handles |
| 15122 | @samp{Ctrl-C}. |
| 15123 | |
| 15124 | @kindex show new-group |
| 15125 | @item show new-group |
| 15126 | Displays current value of new-group boolean. |
| 15127 | |
| 15128 | @kindex set debugevents |
| 15129 | @item set debugevents |
| 15130 | This boolean value adds debug output concerning kernel events related |
| 15131 | to the debuggee seen by the debugger. This includes events that |
| 15132 | signal thread and process creation and exit, DLL loading and |
| 15133 | unloading, console interrupts, and debugging messages produced by the |
| 15134 | Windows @code{OutputDebugString} API call. |
| 15135 | |
| 15136 | @kindex set debugexec |
| 15137 | @item set debugexec |
| 15138 | This boolean value adds debug output concerning execute events |
| 15139 | (such as resume thread) seen by the debugger. |
| 15140 | |
| 15141 | @kindex set debugexceptions |
| 15142 | @item set debugexceptions |
| 15143 | This boolean value adds debug output concerning exceptions in the |
| 15144 | debuggee seen by the debugger. |
| 15145 | |
| 15146 | @kindex set debugmemory |
| 15147 | @item set debugmemory |
| 15148 | This boolean value adds debug output concerning debuggee memory reads |
| 15149 | and writes by the debugger. |
| 15150 | |
| 15151 | @kindex set shell |
| 15152 | @item set shell |
| 15153 | This boolean values specifies whether the debuggee is called |
| 15154 | via a shell or directly (default value is on). |
| 15155 | |
| 15156 | @kindex show shell |
| 15157 | @item show shell |
| 15158 | Displays if the debuggee will be started with a shell. |
| 15159 | |
| 15160 | @end table |
| 15161 | |
| 15162 | @menu |
| 15163 | * Non-debug DLL Symbols:: Support for DLLs without debugging symbols |
| 15164 | @end menu |
| 15165 | |
| 15166 | @node Non-debug DLL Symbols |
| 15167 | @subsubsection Support for DLLs without Debugging Symbols |
| 15168 | @cindex DLLs with no debugging symbols |
| 15169 | @cindex Minimal symbols and DLLs |
| 15170 | |
| 15171 | Very often on windows, some of the DLLs that your program relies on do |
| 15172 | not include symbolic debugging information (for example, |
| 15173 | @file{kernel32.dll}). When @value{GDBN} doesn't recognize any debugging |
| 15174 | symbols in a DLL, it relies on the minimal amount of symbolic |
| 15175 | information contained in the DLL's export table. This section |
| 15176 | describes working with such symbols, known internally to @value{GDBN} as |
| 15177 | ``minimal symbols''. |
| 15178 | |
| 15179 | Note that before the debugged program has started execution, no DLLs |
| 15180 | will have been loaded. The easiest way around this problem is simply to |
| 15181 | start the program --- either by setting a breakpoint or letting the |
| 15182 | program run once to completion. It is also possible to force |
| 15183 | @value{GDBN} to load a particular DLL before starting the executable --- |
| 15184 | see the shared library information in @ref{Files}, or the |
| 15185 | @code{dll-symbols} command in @ref{Cygwin Native}. Currently, |
| 15186 | explicitly loading symbols from a DLL with no debugging information will |
| 15187 | cause the symbol names to be duplicated in @value{GDBN}'s lookup table, |
| 15188 | which may adversely affect symbol lookup performance. |
| 15189 | |
| 15190 | @subsubsection DLL Name Prefixes |
| 15191 | |
| 15192 | In keeping with the naming conventions used by the Microsoft debugging |
| 15193 | tools, DLL export symbols are made available with a prefix based on the |
| 15194 | DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is |
| 15195 | also entered into the symbol table, so @code{CreateFileA} is often |
| 15196 | sufficient. In some cases there will be name clashes within a program |
| 15197 | (particularly if the executable itself includes full debugging symbols) |
| 15198 | necessitating the use of the fully qualified name when referring to the |
| 15199 | contents of the DLL. Use single-quotes around the name to avoid the |
| 15200 | exclamation mark (``!'') being interpreted as a language operator. |
| 15201 | |
| 15202 | Note that the internal name of the DLL may be all upper-case, even |
| 15203 | though the file name of the DLL is lower-case, or vice-versa. Since |
| 15204 | symbols within @value{GDBN} are @emph{case-sensitive} this may cause |
| 15205 | some confusion. If in doubt, try the @code{info functions} and |
| 15206 | @code{info variables} commands or even @code{maint print msymbols} |
| 15207 | (@pxref{Symbols}). Here's an example: |
| 15208 | |
| 15209 | @smallexample |
| 15210 | (@value{GDBP}) info function CreateFileA |
| 15211 | All functions matching regular expression "CreateFileA": |
| 15212 | |
| 15213 | Non-debugging symbols: |
| 15214 | 0x77e885f4 CreateFileA |
| 15215 | 0x77e885f4 KERNEL32!CreateFileA |
| 15216 | @end smallexample |
| 15217 | |
| 15218 | @smallexample |
| 15219 | (@value{GDBP}) info function ! |
| 15220 | All functions matching regular expression "!": |
| 15221 | |
| 15222 | Non-debugging symbols: |
| 15223 | 0x6100114c cygwin1!__assert |
| 15224 | 0x61004034 cygwin1!_dll_crt0@@0 |
| 15225 | 0x61004240 cygwin1!dll_crt0(per_process *) |
| 15226 | [etc...] |
| 15227 | @end smallexample |
| 15228 | |
| 15229 | @subsubsection Working with Minimal Symbols |
| 15230 | |
| 15231 | Symbols extracted from a DLL's export table do not contain very much |
| 15232 | type information. All that @value{GDBN} can do is guess whether a symbol |
| 15233 | refers to a function or variable depending on the linker section that |
| 15234 | contains the symbol. Also note that the actual contents of the memory |
| 15235 | contained in a DLL are not available unless the program is running. This |
| 15236 | means that you cannot examine the contents of a variable or disassemble |
| 15237 | a function within a DLL without a running program. |
| 15238 | |
| 15239 | Variables are generally treated as pointers and dereferenced |
| 15240 | automatically. For this reason, it is often necessary to prefix a |
| 15241 | variable name with the address-of operator (``&'') and provide explicit |
| 15242 | type information in the command. Here's an example of the type of |
| 15243 | problem: |
| 15244 | |
| 15245 | @smallexample |
| 15246 | (@value{GDBP}) print 'cygwin1!__argv' |
| 15247 | $1 = 268572168 |
| 15248 | @end smallexample |
| 15249 | |
| 15250 | @smallexample |
| 15251 | (@value{GDBP}) x 'cygwin1!__argv' |
| 15252 | 0x10021610: "\230y\"" |
| 15253 | @end smallexample |
| 15254 | |
| 15255 | And two possible solutions: |
| 15256 | |
| 15257 | @smallexample |
| 15258 | (@value{GDBP}) print ((char **)'cygwin1!__argv')[0] |
| 15259 | $2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram" |
| 15260 | @end smallexample |
| 15261 | |
| 15262 | @smallexample |
| 15263 | (@value{GDBP}) x/2x &'cygwin1!__argv' |
| 15264 | 0x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000 |
| 15265 | (@value{GDBP}) x/x 0x10021608 |
| 15266 | 0x10021608: 0x0022fd98 |
| 15267 | (@value{GDBP}) x/s 0x0022fd98 |
| 15268 | 0x22fd98: "/cygdrive/c/mydirectory/myprogram" |
| 15269 | @end smallexample |
| 15270 | |
| 15271 | Setting a break point within a DLL is possible even before the program |
| 15272 | starts execution. However, under these circumstances, @value{GDBN} can't |
| 15273 | examine the initial instructions of the function in order to skip the |
| 15274 | function's frame set-up code. You can work around this by using ``*&'' |
| 15275 | to set the breakpoint at a raw memory address: |
| 15276 | |
| 15277 | @smallexample |
| 15278 | (@value{GDBP}) break *&'python22!PyOS_Readline' |
| 15279 | Breakpoint 1 at 0x1e04eff0 |
| 15280 | @end smallexample |
| 15281 | |
| 15282 | The author of these extensions is not entirely convinced that setting a |
| 15283 | break point within a shared DLL like @file{kernel32.dll} is completely |
| 15284 | safe. |
| 15285 | |
| 15286 | @node Hurd Native |
| 15287 | @subsection Commands Specific to @sc{gnu} Hurd Systems |
| 15288 | @cindex @sc{gnu} Hurd debugging |
| 15289 | |
| 15290 | This subsection describes @value{GDBN} commands specific to the |
| 15291 | @sc{gnu} Hurd native debugging. |
| 15292 | |
| 15293 | @table @code |
| 15294 | @item set signals |
| 15295 | @itemx set sigs |
| 15296 | @kindex set signals@r{, Hurd command} |
| 15297 | @kindex set sigs@r{, Hurd command} |
| 15298 | This command toggles the state of inferior signal interception by |
| 15299 | @value{GDBN}. Mach exceptions, such as breakpoint traps, are not |
| 15300 | affected by this command. @code{sigs} is a shorthand alias for |
| 15301 | @code{signals}. |
| 15302 | |
| 15303 | @item show signals |
| 15304 | @itemx show sigs |
| 15305 | @kindex show signals@r{, Hurd command} |
| 15306 | @kindex show sigs@r{, Hurd command} |
| 15307 | Show the current state of intercepting inferior's signals. |
| 15308 | |
| 15309 | @item set signal-thread |
| 15310 | @itemx set sigthread |
| 15311 | @kindex set signal-thread |
| 15312 | @kindex set sigthread |
| 15313 | This command tells @value{GDBN} which thread is the @code{libc} signal |
| 15314 | thread. That thread is run when a signal is delivered to a running |
| 15315 | process. @code{set sigthread} is the shorthand alias of @code{set |
| 15316 | signal-thread}. |
| 15317 | |
| 15318 | @item show signal-thread |
| 15319 | @itemx show sigthread |
| 15320 | @kindex show signal-thread |
| 15321 | @kindex show sigthread |
| 15322 | These two commands show which thread will run when the inferior is |
| 15323 | delivered a signal. |
| 15324 | |
| 15325 | @item set stopped |
| 15326 | @kindex set stopped@r{, Hurd command} |
| 15327 | This commands tells @value{GDBN} that the inferior process is stopped, |
| 15328 | as with the @code{SIGSTOP} signal. The stopped process can be |
| 15329 | continued by delivering a signal to it. |
| 15330 | |
| 15331 | @item show stopped |
| 15332 | @kindex show stopped@r{, Hurd command} |
| 15333 | This command shows whether @value{GDBN} thinks the debuggee is |
| 15334 | stopped. |
| 15335 | |
| 15336 | @item set exceptions |
| 15337 | @kindex set exceptions@r{, Hurd command} |
| 15338 | Use this command to turn off trapping of exceptions in the inferior. |
| 15339 | When exception trapping is off, neither breakpoints nor |
| 15340 | single-stepping will work. To restore the default, set exception |
| 15341 | trapping on. |
| 15342 | |
| 15343 | @item show exceptions |
| 15344 | @kindex show exceptions@r{, Hurd command} |
| 15345 | Show the current state of trapping exceptions in the inferior. |
| 15346 | |
| 15347 | @item set task pause |
| 15348 | @kindex set task@r{, Hurd commands} |
| 15349 | @cindex task attributes (@sc{gnu} Hurd) |
| 15350 | @cindex pause current task (@sc{gnu} Hurd) |
| 15351 | This command toggles task suspension when @value{GDBN} has control. |
| 15352 | Setting it to on takes effect immediately, and the task is suspended |
| 15353 | whenever @value{GDBN} gets control. Setting it to off will take |
| 15354 | effect the next time the inferior is continued. If this option is set |
| 15355 | to off, you can use @code{set thread default pause on} or @code{set |
| 15356 | thread pause on} (see below) to pause individual threads. |
| 15357 | |
| 15358 | @item show task pause |
| 15359 | @kindex show task@r{, Hurd commands} |
| 15360 | Show the current state of task suspension. |
| 15361 | |
| 15362 | @item set task detach-suspend-count |
| 15363 | @cindex task suspend count |
| 15364 | @cindex detach from task, @sc{gnu} Hurd |
| 15365 | This command sets the suspend count the task will be left with when |
| 15366 | @value{GDBN} detaches from it. |
| 15367 | |
| 15368 | @item show task detach-suspend-count |
| 15369 | Show the suspend count the task will be left with when detaching. |
| 15370 | |
| 15371 | @item set task exception-port |
| 15372 | @itemx set task excp |
| 15373 | @cindex task exception port, @sc{gnu} Hurd |
| 15374 | This command sets the task exception port to which @value{GDBN} will |
| 15375 | forward exceptions. The argument should be the value of the @dfn{send |
| 15376 | rights} of the task. @code{set task excp} is a shorthand alias. |
| 15377 | |
| 15378 | @item set noninvasive |
| 15379 | @cindex noninvasive task options |
| 15380 | This command switches @value{GDBN} to a mode that is the least |
| 15381 | invasive as far as interfering with the inferior is concerned. This |
| 15382 | is the same as using @code{set task pause}, @code{set exceptions}, and |
| 15383 | @code{set signals} to values opposite to the defaults. |
| 15384 | |
| 15385 | @item info send-rights |
| 15386 | @itemx info receive-rights |
| 15387 | @itemx info port-rights |
| 15388 | @itemx info port-sets |
| 15389 | @itemx info dead-names |
| 15390 | @itemx info ports |
| 15391 | @itemx info psets |
| 15392 | @cindex send rights, @sc{gnu} Hurd |
| 15393 | @cindex receive rights, @sc{gnu} Hurd |
| 15394 | @cindex port rights, @sc{gnu} Hurd |
| 15395 | @cindex port sets, @sc{gnu} Hurd |
| 15396 | @cindex dead names, @sc{gnu} Hurd |
| 15397 | These commands display information about, respectively, send rights, |
| 15398 | receive rights, port rights, port sets, and dead names of a task. |
| 15399 | There are also shorthand aliases: @code{info ports} for @code{info |
| 15400 | port-rights} and @code{info psets} for @code{info port-sets}. |
| 15401 | |
| 15402 | @item set thread pause |
| 15403 | @kindex set thread@r{, Hurd command} |
| 15404 | @cindex thread properties, @sc{gnu} Hurd |
| 15405 | @cindex pause current thread (@sc{gnu} Hurd) |
| 15406 | This command toggles current thread suspension when @value{GDBN} has |
| 15407 | control. Setting it to on takes effect immediately, and the current |
| 15408 | thread is suspended whenever @value{GDBN} gets control. Setting it to |
| 15409 | off will take effect the next time the inferior is continued. |
| 15410 | Normally, this command has no effect, since when @value{GDBN} has |
| 15411 | control, the whole task is suspended. However, if you used @code{set |
| 15412 | task pause off} (see above), this command comes in handy to suspend |
| 15413 | only the current thread. |
| 15414 | |
| 15415 | @item show thread pause |
| 15416 | @kindex show thread@r{, Hurd command} |
| 15417 | This command shows the state of current thread suspension. |
| 15418 | |
| 15419 | @item set thread run |
| 15420 | This command sets whether the current thread is allowed to run. |
| 15421 | |
| 15422 | @item show thread run |
| 15423 | Show whether the current thread is allowed to run. |
| 15424 | |
| 15425 | @item set thread detach-suspend-count |
| 15426 | @cindex thread suspend count, @sc{gnu} Hurd |
| 15427 | @cindex detach from thread, @sc{gnu} Hurd |
| 15428 | This command sets the suspend count @value{GDBN} will leave on a |
| 15429 | thread when detaching. This number is relative to the suspend count |
| 15430 | found by @value{GDBN} when it notices the thread; use @code{set thread |
| 15431 | takeover-suspend-count} to force it to an absolute value. |
| 15432 | |
| 15433 | @item show thread detach-suspend-count |
| 15434 | Show the suspend count @value{GDBN} will leave on the thread when |
| 15435 | detaching. |
| 15436 | |
| 15437 | @item set thread exception-port |
| 15438 | @itemx set thread excp |
| 15439 | Set the thread exception port to which to forward exceptions. This |
| 15440 | overrides the port set by @code{set task exception-port} (see above). |
| 15441 | @code{set thread excp} is the shorthand alias. |
| 15442 | |
| 15443 | @item set thread takeover-suspend-count |
| 15444 | Normally, @value{GDBN}'s thread suspend counts are relative to the |
| 15445 | value @value{GDBN} finds when it notices each thread. This command |
| 15446 | changes the suspend counts to be absolute instead. |
| 15447 | |
| 15448 | @item set thread default |
| 15449 | @itemx show thread default |
| 15450 | @cindex thread default settings, @sc{gnu} Hurd |
| 15451 | Each of the above @code{set thread} commands has a @code{set thread |
| 15452 | default} counterpart (e.g., @code{set thread default pause}, @code{set |
| 15453 | thread default exception-port}, etc.). The @code{thread default} |
| 15454 | variety of commands sets the default thread properties for all |
| 15455 | threads; you can then change the properties of individual threads with |
| 15456 | the non-default commands. |
| 15457 | @end table |
| 15458 | |
| 15459 | |
| 15460 | @node Neutrino |
| 15461 | @subsection QNX Neutrino |
| 15462 | @cindex QNX Neutrino |
| 15463 | |
| 15464 | @value{GDBN} provides the following commands specific to the QNX |
| 15465 | Neutrino target: |
| 15466 | |
| 15467 | @table @code |
| 15468 | @item set debug nto-debug |
| 15469 | @kindex set debug nto-debug |
| 15470 | When set to on, enables debugging messages specific to the QNX |
| 15471 | Neutrino support. |
| 15472 | |
| 15473 | @item show debug nto-debug |
| 15474 | @kindex show debug nto-debug |
| 15475 | Show the current state of QNX Neutrino messages. |
| 15476 | @end table |
| 15477 | |
| 15478 | @node Darwin |
| 15479 | @subsection Darwin |
| 15480 | @cindex Darwin |
| 15481 | |
| 15482 | @value{GDBN} provides the following commands specific to the Darwin target: |
| 15483 | |
| 15484 | @table @code |
| 15485 | @item set debug darwin @var{num} |
| 15486 | @kindex set debug darwin |
| 15487 | When set to a non zero value, enables debugging messages specific to |
| 15488 | the Darwin support. Higher values produce more verbose output. |
| 15489 | |
| 15490 | @item show debug darwin |
| 15491 | @kindex show debug darwin |
| 15492 | Show the current state of Darwin messages. |
| 15493 | |
| 15494 | @item set debug mach-o @var{num} |
| 15495 | @kindex set debug mach-o |
| 15496 | When set to a non zero value, enables debugging messages while |
| 15497 | @value{GDBN} is reading Darwin object files. (@dfn{Mach-O} is the |
| 15498 | file format used on Darwin for object and executable files.) Higher |
| 15499 | values produce more verbose output. This is a command to diagnose |
| 15500 | problems internal to @value{GDBN} and should not be needed in normal |
| 15501 | usage. |
| 15502 | |
| 15503 | @item show debug mach-o |
| 15504 | @kindex show debug mach-o |
| 15505 | Show the current state of Mach-O file messages. |
| 15506 | |
| 15507 | @item set mach-exceptions on |
| 15508 | @itemx set mach-exceptions off |
| 15509 | @kindex set mach-exceptions |
| 15510 | On Darwin, faults are first reported as a Mach exception and are then |
| 15511 | mapped to a Posix signal. Use this command to turn on trapping of |
| 15512 | Mach exceptions in the inferior. This might be sometimes useful to |
| 15513 | better understand the cause of a fault. The default is off. |
| 15514 | |
| 15515 | @item show mach-exceptions |
| 15516 | @kindex show mach-exceptions |
| 15517 | Show the current state of exceptions trapping. |
| 15518 | @end table |
| 15519 | |
| 15520 | |
| 15521 | @node Embedded OS |
| 15522 | @section Embedded Operating Systems |
| 15523 | |
| 15524 | This section describes configurations involving the debugging of |
| 15525 | embedded operating systems that are available for several different |
| 15526 | architectures. |
| 15527 | |
| 15528 | @menu |
| 15529 | * VxWorks:: Using @value{GDBN} with VxWorks |
| 15530 | @end menu |
| 15531 | |
| 15532 | @value{GDBN} includes the ability to debug programs running on |
| 15533 | various real-time operating systems. |
| 15534 | |
| 15535 | @node VxWorks |
| 15536 | @subsection Using @value{GDBN} with VxWorks |
| 15537 | |
| 15538 | @cindex VxWorks |
| 15539 | |
| 15540 | @table @code |
| 15541 | |
| 15542 | @kindex target vxworks |
| 15543 | @item target vxworks @var{machinename} |
| 15544 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} |
| 15545 | is the target system's machine name or IP address. |
| 15546 | |
| 15547 | @end table |
| 15548 | |
| 15549 | On VxWorks, @code{load} links @var{filename} dynamically on the |
| 15550 | current target system as well as adding its symbols in @value{GDBN}. |
| 15551 | |
| 15552 | @value{GDBN} enables developers to spawn and debug tasks running on networked |
| 15553 | VxWorks targets from a Unix host. Already-running tasks spawned from |
| 15554 | the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on |
| 15555 | both the Unix host and on the VxWorks target. The program |
| 15556 | @code{@value{GDBP}} is installed and executed on the Unix host. (It may be |
| 15557 | installed with the name @code{vxgdb}, to distinguish it from a |
| 15558 | @value{GDBN} for debugging programs on the host itself.) |
| 15559 | |
| 15560 | @table @code |
| 15561 | @item VxWorks-timeout @var{args} |
| 15562 | @kindex vxworks-timeout |
| 15563 | All VxWorks-based targets now support the option @code{vxworks-timeout}. |
| 15564 | This option is set by the user, and @var{args} represents the number of |
| 15565 | seconds @value{GDBN} waits for responses to rpc's. You might use this if |
| 15566 | your VxWorks target is a slow software simulator or is on the far side |
| 15567 | of a thin network line. |
| 15568 | @end table |
| 15569 | |
| 15570 | The following information on connecting to VxWorks was current when |
| 15571 | this manual was produced; newer releases of VxWorks may use revised |
| 15572 | procedures. |
| 15573 | |
| 15574 | @findex INCLUDE_RDB |
| 15575 | To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel |
| 15576 | to include the remote debugging interface routines in the VxWorks |
| 15577 | library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the |
| 15578 | VxWorks configuration file @file{configAll.h} and rebuild your VxWorks |
| 15579 | kernel. The resulting kernel contains @file{rdb.a}, and spawns the |
| 15580 | source debugging task @code{tRdbTask} when VxWorks is booted. For more |
| 15581 | information on configuring and remaking VxWorks, see the manufacturer's |
| 15582 | manual. |
| 15583 | @c VxWorks, see the @cite{VxWorks Programmer's Guide}. |
| 15584 | |
| 15585 | Once you have included @file{rdb.a} in your VxWorks system image and set |
| 15586 | your Unix execution search path to find @value{GDBN}, you are ready to |
| 15587 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or |
| 15588 | @code{vxgdb}, depending on your installation). |
| 15589 | |
| 15590 | @value{GDBN} comes up showing the prompt: |
| 15591 | |
| 15592 | @smallexample |
| 15593 | (vxgdb) |
| 15594 | @end smallexample |
| 15595 | |
| 15596 | @menu |
| 15597 | * VxWorks Connection:: Connecting to VxWorks |
| 15598 | * VxWorks Download:: VxWorks download |
| 15599 | * VxWorks Attach:: Running tasks |
| 15600 | @end menu |
| 15601 | |
| 15602 | @node VxWorks Connection |
| 15603 | @subsubsection Connecting to VxWorks |
| 15604 | |
| 15605 | The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the |
| 15606 | network. To connect to a target whose host name is ``@code{tt}'', type: |
| 15607 | |
| 15608 | @smallexample |
| 15609 | (vxgdb) target vxworks tt |
| 15610 | @end smallexample |
| 15611 | |
| 15612 | @need 750 |
| 15613 | @value{GDBN} displays messages like these: |
| 15614 | |
| 15615 | @smallexample |
| 15616 | Attaching remote machine across net... |
| 15617 | Connected to tt. |
| 15618 | @end smallexample |
| 15619 | |
| 15620 | @need 1000 |
| 15621 | @value{GDBN} then attempts to read the symbol tables of any object modules |
| 15622 | loaded into the VxWorks target since it was last booted. @value{GDBN} locates |
| 15623 | these files by searching the directories listed in the command search |
| 15624 | path (@pxref{Environment, ,Your Program's Environment}); if it fails |
| 15625 | to find an object file, it displays a message such as: |
| 15626 | |
| 15627 | @smallexample |
| 15628 | prog.o: No such file or directory. |
| 15629 | @end smallexample |
| 15630 | |
| 15631 | When this happens, add the appropriate directory to the search path with |
| 15632 | the @value{GDBN} command @code{path}, and execute the @code{target} |
| 15633 | command again. |
| 15634 | |
| 15635 | @node VxWorks Download |
| 15636 | @subsubsection VxWorks Download |
| 15637 | |
| 15638 | @cindex download to VxWorks |
| 15639 | If you have connected to the VxWorks target and you want to debug an |
| 15640 | object that has not yet been loaded, you can use the @value{GDBN} |
| 15641 | @code{load} command to download a file from Unix to VxWorks |
| 15642 | incrementally. The object file given as an argument to the @code{load} |
| 15643 | command is actually opened twice: first by the VxWorks target in order |
| 15644 | to download the code, then by @value{GDBN} in order to read the symbol |
| 15645 | table. This can lead to problems if the current working directories on |
| 15646 | the two systems differ. If both systems have NFS mounted the same |
| 15647 | filesystems, you can avoid these problems by using absolute paths. |
| 15648 | Otherwise, it is simplest to set the working directory on both systems |
| 15649 | to the directory in which the object file resides, and then to reference |
| 15650 | the file by its name, without any path. For instance, a program |
| 15651 | @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks |
| 15652 | and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this |
| 15653 | program, type this on VxWorks: |
| 15654 | |
| 15655 | @smallexample |
| 15656 | -> cd "@var{vxpath}/vw/demo/rdb" |
| 15657 | @end smallexample |
| 15658 | |
| 15659 | @noindent |
| 15660 | Then, in @value{GDBN}, type: |
| 15661 | |
| 15662 | @smallexample |
| 15663 | (vxgdb) cd @var{hostpath}/vw/demo/rdb |
| 15664 | (vxgdb) load prog.o |
| 15665 | @end smallexample |
| 15666 | |
| 15667 | @value{GDBN} displays a response similar to this: |
| 15668 | |
| 15669 | @smallexample |
| 15670 | Reading symbol data from wherever/vw/demo/rdb/prog.o... done. |
| 15671 | @end smallexample |
| 15672 | |
| 15673 | You can also use the @code{load} command to reload an object module |
| 15674 | after editing and recompiling the corresponding source file. Note that |
| 15675 | this makes @value{GDBN} delete all currently-defined breakpoints, |
| 15676 | auto-displays, and convenience variables, and to clear the value |
| 15677 | history. (This is necessary in order to preserve the integrity of |
| 15678 | debugger's data structures that reference the target system's symbol |
| 15679 | table.) |
| 15680 | |
| 15681 | @node VxWorks Attach |
| 15682 | @subsubsection Running Tasks |
| 15683 | |
| 15684 | @cindex running VxWorks tasks |
| 15685 | You can also attach to an existing task using the @code{attach} command as |
| 15686 | follows: |
| 15687 | |
| 15688 | @smallexample |
| 15689 | (vxgdb) attach @var{task} |
| 15690 | @end smallexample |
| 15691 | |
| 15692 | @noindent |
| 15693 | where @var{task} is the VxWorks hexadecimal task ID. The task can be running |
| 15694 | or suspended when you attach to it. Running tasks are suspended at |
| 15695 | the time of attachment. |
| 15696 | |
| 15697 | @node Embedded Processors |
| 15698 | @section Embedded Processors |
| 15699 | |
| 15700 | This section goes into details specific to particular embedded |
| 15701 | configurations. |
| 15702 | |
| 15703 | @cindex send command to simulator |
| 15704 | Whenever a specific embedded processor has a simulator, @value{GDBN} |
| 15705 | allows to send an arbitrary command to the simulator. |
| 15706 | |
| 15707 | @table @code |
| 15708 | @item sim @var{command} |
| 15709 | @kindex sim@r{, a command} |
| 15710 | Send an arbitrary @var{command} string to the simulator. Consult the |
| 15711 | documentation for the specific simulator in use for information about |
| 15712 | acceptable commands. |
| 15713 | @end table |
| 15714 | |
| 15715 | |
| 15716 | @menu |
| 15717 | * ARM:: ARM RDI |
| 15718 | * M32R/D:: Renesas M32R/D |
| 15719 | * M68K:: Motorola M68K |
| 15720 | * MIPS Embedded:: MIPS Embedded |
| 15721 | * OpenRISC 1000:: OpenRisc 1000 |
| 15722 | * PA:: HP PA Embedded |
| 15723 | * PowerPC Embedded:: PowerPC Embedded |
| 15724 | * Sparclet:: Tsqware Sparclet |
| 15725 | * Sparclite:: Fujitsu Sparclite |
| 15726 | * Z8000:: Zilog Z8000 |
| 15727 | * AVR:: Atmel AVR |
| 15728 | * CRIS:: CRIS |
| 15729 | * Super-H:: Renesas Super-H |
| 15730 | @end menu |
| 15731 | |
| 15732 | @node ARM |
| 15733 | @subsection ARM |
| 15734 | @cindex ARM RDI |
| 15735 | |
| 15736 | @table @code |
| 15737 | @kindex target rdi |
| 15738 | @item target rdi @var{dev} |
| 15739 | ARM Angel monitor, via RDI library interface to ADP protocol. You may |
| 15740 | use this target to communicate with both boards running the Angel |
| 15741 | monitor, or with the EmbeddedICE JTAG debug device. |
| 15742 | |
| 15743 | @kindex target rdp |
| 15744 | @item target rdp @var{dev} |
| 15745 | ARM Demon monitor. |
| 15746 | |
| 15747 | @end table |
| 15748 | |
| 15749 | @value{GDBN} provides the following ARM-specific commands: |
| 15750 | |
| 15751 | @table @code |
| 15752 | @item set arm disassembler |
| 15753 | @kindex set arm |
| 15754 | This commands selects from a list of disassembly styles. The |
| 15755 | @code{"std"} style is the standard style. |
| 15756 | |
| 15757 | @item show arm disassembler |
| 15758 | @kindex show arm |
| 15759 | Show the current disassembly style. |
| 15760 | |
| 15761 | @item set arm apcs32 |
| 15762 | @cindex ARM 32-bit mode |
| 15763 | This command toggles ARM operation mode between 32-bit and 26-bit. |
| 15764 | |
| 15765 | @item show arm apcs32 |
| 15766 | Display the current usage of the ARM 32-bit mode. |
| 15767 | |
| 15768 | @item set arm fpu @var{fputype} |
| 15769 | This command sets the ARM floating-point unit (FPU) type. The |
| 15770 | argument @var{fputype} can be one of these: |
| 15771 | |
| 15772 | @table @code |
| 15773 | @item auto |
| 15774 | Determine the FPU type by querying the OS ABI. |
| 15775 | @item softfpa |
| 15776 | Software FPU, with mixed-endian doubles on little-endian ARM |
| 15777 | processors. |
| 15778 | @item fpa |
| 15779 | GCC-compiled FPA co-processor. |
| 15780 | @item softvfp |
| 15781 | Software FPU with pure-endian doubles. |
| 15782 | @item vfp |
| 15783 | VFP co-processor. |
| 15784 | @end table |
| 15785 | |
| 15786 | @item show arm fpu |
| 15787 | Show the current type of the FPU. |
| 15788 | |
| 15789 | @item set arm abi |
| 15790 | This command forces @value{GDBN} to use the specified ABI. |
| 15791 | |
| 15792 | @item show arm abi |
| 15793 | Show the currently used ABI. |
| 15794 | |
| 15795 | @item set arm fallback-mode (arm|thumb|auto) |
| 15796 | @value{GDBN} uses the symbol table, when available, to determine |
| 15797 | whether instructions are ARM or Thumb. This command controls |
| 15798 | @value{GDBN}'s default behavior when the symbol table is not |
| 15799 | available. The default is @samp{auto}, which causes @value{GDBN} to |
| 15800 | use the current execution mode (from the @code{T} bit in the @code{CPSR} |
| 15801 | register). |
| 15802 | |
| 15803 | @item show arm fallback-mode |
| 15804 | Show the current fallback instruction mode. |
| 15805 | |
| 15806 | @item set arm force-mode (arm|thumb|auto) |
| 15807 | This command overrides use of the symbol table to determine whether |
| 15808 | instructions are ARM or Thumb. The default is @samp{auto}, which |
| 15809 | causes @value{GDBN} to use the symbol table and then the setting |
| 15810 | of @samp{set arm fallback-mode}. |
| 15811 | |
| 15812 | @item show arm force-mode |
| 15813 | Show the current forced instruction mode. |
| 15814 | |
| 15815 | @item set debug arm |
| 15816 | Toggle whether to display ARM-specific debugging messages from the ARM |
| 15817 | target support subsystem. |
| 15818 | |
| 15819 | @item show debug arm |
| 15820 | Show whether ARM-specific debugging messages are enabled. |
| 15821 | @end table |
| 15822 | |
| 15823 | The following commands are available when an ARM target is debugged |
| 15824 | using the RDI interface: |
| 15825 | |
| 15826 | @table @code |
| 15827 | @item rdilogfile @r{[}@var{file}@r{]} |
| 15828 | @kindex rdilogfile |
| 15829 | @cindex ADP (Angel Debugger Protocol) logging |
| 15830 | Set the filename for the ADP (Angel Debugger Protocol) packet log. |
| 15831 | With an argument, sets the log file to the specified @var{file}. With |
| 15832 | no argument, show the current log file name. The default log file is |
| 15833 | @file{rdi.log}. |
| 15834 | |
| 15835 | @item rdilogenable @r{[}@var{arg}@r{]} |
| 15836 | @kindex rdilogenable |
| 15837 | Control logging of ADP packets. With an argument of 1 or @code{"yes"} |
| 15838 | enables logging, with an argument 0 or @code{"no"} disables it. With |
| 15839 | no arguments displays the current setting. When logging is enabled, |
| 15840 | ADP packets exchanged between @value{GDBN} and the RDI target device |
| 15841 | are logged to a file. |
| 15842 | |
| 15843 | @item set rdiromatzero |
| 15844 | @kindex set rdiromatzero |
| 15845 | @cindex ROM at zero address, RDI |
| 15846 | Tell @value{GDBN} whether the target has ROM at address 0. If on, |
| 15847 | vector catching is disabled, so that zero address can be used. If off |
| 15848 | (the default), vector catching is enabled. For this command to take |
| 15849 | effect, it needs to be invoked prior to the @code{target rdi} command. |
| 15850 | |
| 15851 | @item show rdiromatzero |
| 15852 | @kindex show rdiromatzero |
| 15853 | Show the current setting of ROM at zero address. |
| 15854 | |
| 15855 | @item set rdiheartbeat |
| 15856 | @kindex set rdiheartbeat |
| 15857 | @cindex RDI heartbeat |
| 15858 | Enable or disable RDI heartbeat packets. It is not recommended to |
| 15859 | turn on this option, since it confuses ARM and EPI JTAG interface, as |
| 15860 | well as the Angel monitor. |
| 15861 | |
| 15862 | @item show rdiheartbeat |
| 15863 | @kindex show rdiheartbeat |
| 15864 | Show the setting of RDI heartbeat packets. |
| 15865 | @end table |
| 15866 | |
| 15867 | |
| 15868 | @node M32R/D |
| 15869 | @subsection Renesas M32R/D and M32R/SDI |
| 15870 | |
| 15871 | @table @code |
| 15872 | @kindex target m32r |
| 15873 | @item target m32r @var{dev} |
| 15874 | Renesas M32R/D ROM monitor. |
| 15875 | |
| 15876 | @kindex target m32rsdi |
| 15877 | @item target m32rsdi @var{dev} |
| 15878 | Renesas M32R SDI server, connected via parallel port to the board. |
| 15879 | @end table |
| 15880 | |
| 15881 | The following @value{GDBN} commands are specific to the M32R monitor: |
| 15882 | |
| 15883 | @table @code |
| 15884 | @item set download-path @var{path} |
| 15885 | @kindex set download-path |
| 15886 | @cindex find downloadable @sc{srec} files (M32R) |
| 15887 | Set the default path for finding downloadable @sc{srec} files. |
| 15888 | |
| 15889 | @item show download-path |
| 15890 | @kindex show download-path |
| 15891 | Show the default path for downloadable @sc{srec} files. |
| 15892 | |
| 15893 | @item set board-address @var{addr} |
| 15894 | @kindex set board-address |
| 15895 | @cindex M32-EVA target board address |
| 15896 | Set the IP address for the M32R-EVA target board. |
| 15897 | |
| 15898 | @item show board-address |
| 15899 | @kindex show board-address |
| 15900 | Show the current IP address of the target board. |
| 15901 | |
| 15902 | @item set server-address @var{addr} |
| 15903 | @kindex set server-address |
| 15904 | @cindex download server address (M32R) |
| 15905 | Set the IP address for the download server, which is the @value{GDBN}'s |
| 15906 | host machine. |
| 15907 | |
| 15908 | @item show server-address |
| 15909 | @kindex show server-address |
| 15910 | Display the IP address of the download server. |
| 15911 | |
| 15912 | @item upload @r{[}@var{file}@r{]} |
| 15913 | @kindex upload@r{, M32R} |
| 15914 | Upload the specified @sc{srec} @var{file} via the monitor's Ethernet |
| 15915 | upload capability. If no @var{file} argument is given, the current |
| 15916 | executable file is uploaded. |
| 15917 | |
| 15918 | @item tload @r{[}@var{file}@r{]} |
| 15919 | @kindex tload@r{, M32R} |
| 15920 | Test the @code{upload} command. |
| 15921 | @end table |
| 15922 | |
| 15923 | The following commands are available for M32R/SDI: |
| 15924 | |
| 15925 | @table @code |
| 15926 | @item sdireset |
| 15927 | @kindex sdireset |
| 15928 | @cindex reset SDI connection, M32R |
| 15929 | This command resets the SDI connection. |
| 15930 | |
| 15931 | @item sdistatus |
| 15932 | @kindex sdistatus |
| 15933 | This command shows the SDI connection status. |
| 15934 | |
| 15935 | @item debug_chaos |
| 15936 | @kindex debug_chaos |
| 15937 | @cindex M32R/Chaos debugging |
| 15938 | Instructs the remote that M32R/Chaos debugging is to be used. |
| 15939 | |
| 15940 | @item use_debug_dma |
| 15941 | @kindex use_debug_dma |
| 15942 | Instructs the remote to use the DEBUG_DMA method of accessing memory. |
| 15943 | |
| 15944 | @item use_mon_code |
| 15945 | @kindex use_mon_code |
| 15946 | Instructs the remote to use the MON_CODE method of accessing memory. |
| 15947 | |
| 15948 | @item use_ib_break |
| 15949 | @kindex use_ib_break |
| 15950 | Instructs the remote to set breakpoints by IB break. |
| 15951 | |
| 15952 | @item use_dbt_break |
| 15953 | @kindex use_dbt_break |
| 15954 | Instructs the remote to set breakpoints by DBT. |
| 15955 | @end table |
| 15956 | |
| 15957 | @node M68K |
| 15958 | @subsection M68k |
| 15959 | |
| 15960 | The Motorola m68k configuration includes ColdFire support, and a |
| 15961 | target command for the following ROM monitor. |
| 15962 | |
| 15963 | @table @code |
| 15964 | |
| 15965 | @kindex target dbug |
| 15966 | @item target dbug @var{dev} |
| 15967 | dBUG ROM monitor for Motorola ColdFire. |
| 15968 | |
| 15969 | @end table |
| 15970 | |
| 15971 | @node MIPS Embedded |
| 15972 | @subsection MIPS Embedded |
| 15973 | |
| 15974 | @cindex MIPS boards |
| 15975 | @value{GDBN} can use the MIPS remote debugging protocol to talk to a |
| 15976 | MIPS board attached to a serial line. This is available when |
| 15977 | you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. |
| 15978 | |
| 15979 | @need 1000 |
| 15980 | Use these @value{GDBN} commands to specify the connection to your target board: |
| 15981 | |
| 15982 | @table @code |
| 15983 | @item target mips @var{port} |
| 15984 | @kindex target mips @var{port} |
| 15985 | To run a program on the board, start up @code{@value{GDBP}} with the |
| 15986 | name of your program as the argument. To connect to the board, use the |
| 15987 | command @samp{target mips @var{port}}, where @var{port} is the name of |
| 15988 | the serial port connected to the board. If the program has not already |
| 15989 | been downloaded to the board, you may use the @code{load} command to |
| 15990 | download it. You can then use all the usual @value{GDBN} commands. |
| 15991 | |
| 15992 | For example, this sequence connects to the target board through a serial |
| 15993 | port, and loads and runs a program called @var{prog} through the |
| 15994 | debugger: |
| 15995 | |
| 15996 | @smallexample |
| 15997 | host$ @value{GDBP} @var{prog} |
| 15998 | @value{GDBN} is free software and @dots{} |
| 15999 | (@value{GDBP}) target mips /dev/ttyb |
| 16000 | (@value{GDBP}) load @var{prog} |
| 16001 | (@value{GDBP}) run |
| 16002 | @end smallexample |
| 16003 | |
| 16004 | @item target mips @var{hostname}:@var{portnumber} |
| 16005 | On some @value{GDBN} host configurations, you can specify a TCP |
| 16006 | connection (for instance, to a serial line managed by a terminal |
| 16007 | concentrator) instead of a serial port, using the syntax |
| 16008 | @samp{@var{hostname}:@var{portnumber}}. |
| 16009 | |
| 16010 | @item target pmon @var{port} |
| 16011 | @kindex target pmon @var{port} |
| 16012 | PMON ROM monitor. |
| 16013 | |
| 16014 | @item target ddb @var{port} |
| 16015 | @kindex target ddb @var{port} |
| 16016 | NEC's DDB variant of PMON for Vr4300. |
| 16017 | |
| 16018 | @item target lsi @var{port} |
| 16019 | @kindex target lsi @var{port} |
| 16020 | LSI variant of PMON. |
| 16021 | |
| 16022 | @kindex target r3900 |
| 16023 | @item target r3900 @var{dev} |
| 16024 | Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips. |
| 16025 | |
| 16026 | @kindex target array |
| 16027 | @item target array @var{dev} |
| 16028 | Array Tech LSI33K RAID controller board. |
| 16029 | |
| 16030 | @end table |
| 16031 | |
| 16032 | |
| 16033 | @noindent |
| 16034 | @value{GDBN} also supports these special commands for MIPS targets: |
| 16035 | |
| 16036 | @table @code |
| 16037 | @item set mipsfpu double |
| 16038 | @itemx set mipsfpu single |
| 16039 | @itemx set mipsfpu none |
| 16040 | @itemx set mipsfpu auto |
| 16041 | @itemx show mipsfpu |
| 16042 | @kindex set mipsfpu |
| 16043 | @kindex show mipsfpu |
| 16044 | @cindex MIPS remote floating point |
| 16045 | @cindex floating point, MIPS remote |
| 16046 | If your target board does not support the MIPS floating point |
| 16047 | coprocessor, you should use the command @samp{set mipsfpu none} (if you |
| 16048 | need this, you may wish to put the command in your @value{GDBN} init |
| 16049 | file). This tells @value{GDBN} how to find the return value of |
| 16050 | functions which return floating point values. It also allows |
| 16051 | @value{GDBN} to avoid saving the floating point registers when calling |
| 16052 | functions on the board. If you are using a floating point coprocessor |
| 16053 | with only single precision floating point support, as on the @sc{r4650} |
| 16054 | processor, use the command @samp{set mipsfpu single}. The default |
| 16055 | double precision floating point coprocessor may be selected using |
| 16056 | @samp{set mipsfpu double}. |
| 16057 | |
| 16058 | In previous versions the only choices were double precision or no |
| 16059 | floating point, so @samp{set mipsfpu on} will select double precision |
| 16060 | and @samp{set mipsfpu off} will select no floating point. |
| 16061 | |
| 16062 | As usual, you can inquire about the @code{mipsfpu} variable with |
| 16063 | @samp{show mipsfpu}. |
| 16064 | |
| 16065 | @item set timeout @var{seconds} |
| 16066 | @itemx set retransmit-timeout @var{seconds} |
| 16067 | @itemx show timeout |
| 16068 | @itemx show retransmit-timeout |
| 16069 | @cindex @code{timeout}, MIPS protocol |
| 16070 | @cindex @code{retransmit-timeout}, MIPS protocol |
| 16071 | @kindex set timeout |
| 16072 | @kindex show timeout |
| 16073 | @kindex set retransmit-timeout |
| 16074 | @kindex show retransmit-timeout |
| 16075 | You can control the timeout used while waiting for a packet, in the MIPS |
| 16076 | remote protocol, with the @code{set timeout @var{seconds}} command. The |
| 16077 | default is 5 seconds. Similarly, you can control the timeout used while |
| 16078 | waiting for an acknowledgment of a packet with the @code{set |
| 16079 | retransmit-timeout @var{seconds}} command. The default is 3 seconds. |
| 16080 | You can inspect both values with @code{show timeout} and @code{show |
| 16081 | retransmit-timeout}. (These commands are @emph{only} available when |
| 16082 | @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) |
| 16083 | |
| 16084 | The timeout set by @code{set timeout} does not apply when @value{GDBN} |
| 16085 | is waiting for your program to stop. In that case, @value{GDBN} waits |
| 16086 | forever because it has no way of knowing how long the program is going |
| 16087 | to run before stopping. |
| 16088 | |
| 16089 | @item set syn-garbage-limit @var{num} |
| 16090 | @kindex set syn-garbage-limit@r{, MIPS remote} |
| 16091 | @cindex synchronize with remote MIPS target |
| 16092 | Limit the maximum number of characters @value{GDBN} should ignore when |
| 16093 | it tries to synchronize with the remote target. The default is 10 |
| 16094 | characters. Setting the limit to -1 means there's no limit. |
| 16095 | |
| 16096 | @item show syn-garbage-limit |
| 16097 | @kindex show syn-garbage-limit@r{, MIPS remote} |
| 16098 | Show the current limit on the number of characters to ignore when |
| 16099 | trying to synchronize with the remote system. |
| 16100 | |
| 16101 | @item set monitor-prompt @var{prompt} |
| 16102 | @kindex set monitor-prompt@r{, MIPS remote} |
| 16103 | @cindex remote monitor prompt |
| 16104 | Tell @value{GDBN} to expect the specified @var{prompt} string from the |
| 16105 | remote monitor. The default depends on the target: |
| 16106 | @table @asis |
| 16107 | @item pmon target |
| 16108 | @samp{PMON} |
| 16109 | @item ddb target |
| 16110 | @samp{NEC010} |
| 16111 | @item lsi target |
| 16112 | @samp{PMON>} |
| 16113 | @end table |
| 16114 | |
| 16115 | @item show monitor-prompt |
| 16116 | @kindex show monitor-prompt@r{, MIPS remote} |
| 16117 | Show the current strings @value{GDBN} expects as the prompt from the |
| 16118 | remote monitor. |
| 16119 | |
| 16120 | @item set monitor-warnings |
| 16121 | @kindex set monitor-warnings@r{, MIPS remote} |
| 16122 | Enable or disable monitor warnings about hardware breakpoints. This |
| 16123 | has effect only for the @code{lsi} target. When on, @value{GDBN} will |
| 16124 | display warning messages whose codes are returned by the @code{lsi} |
| 16125 | PMON monitor for breakpoint commands. |
| 16126 | |
| 16127 | @item show monitor-warnings |
| 16128 | @kindex show monitor-warnings@r{, MIPS remote} |
| 16129 | Show the current setting of printing monitor warnings. |
| 16130 | |
| 16131 | @item pmon @var{command} |
| 16132 | @kindex pmon@r{, MIPS remote} |
| 16133 | @cindex send PMON command |
| 16134 | This command allows sending an arbitrary @var{command} string to the |
| 16135 | monitor. The monitor must be in debug mode for this to work. |
| 16136 | @end table |
| 16137 | |
| 16138 | @node OpenRISC 1000 |
| 16139 | @subsection OpenRISC 1000 |
| 16140 | @cindex OpenRISC 1000 |
| 16141 | |
| 16142 | @cindex or1k boards |
| 16143 | See OR1k Architecture document (@uref{www.opencores.org}) for more information |
| 16144 | about platform and commands. |
| 16145 | |
| 16146 | @table @code |
| 16147 | |
| 16148 | @kindex target jtag |
| 16149 | @item target jtag jtag://@var{host}:@var{port} |
| 16150 | |
| 16151 | Connects to remote JTAG server. |
| 16152 | JTAG remote server can be either an or1ksim or JTAG server, |
| 16153 | connected via parallel port to the board. |
| 16154 | |
| 16155 | Example: @code{target jtag jtag://localhost:9999} |
| 16156 | |
| 16157 | @kindex or1ksim |
| 16158 | @item or1ksim @var{command} |
| 16159 | If connected to @code{or1ksim} OpenRISC 1000 Architectural |
| 16160 | Simulator, proprietary commands can be executed. |
| 16161 | |
| 16162 | @kindex info or1k spr |
| 16163 | @item info or1k spr |
| 16164 | Displays spr groups. |
| 16165 | |
| 16166 | @item info or1k spr @var{group} |
| 16167 | @itemx info or1k spr @var{groupno} |
| 16168 | Displays register names in selected group. |
| 16169 | |
| 16170 | @item info or1k spr @var{group} @var{register} |
| 16171 | @itemx info or1k spr @var{register} |
| 16172 | @itemx info or1k spr @var{groupno} @var{registerno} |
| 16173 | @itemx info or1k spr @var{registerno} |
| 16174 | Shows information about specified spr register. |
| 16175 | |
| 16176 | @kindex spr |
| 16177 | @item spr @var{group} @var{register} @var{value} |
| 16178 | @itemx spr @var{register @var{value}} |
| 16179 | @itemx spr @var{groupno} @var{registerno @var{value}} |
| 16180 | @itemx spr @var{registerno @var{value}} |
| 16181 | Writes @var{value} to specified spr register. |
| 16182 | @end table |
| 16183 | |
| 16184 | Some implementations of OpenRISC 1000 Architecture also have hardware trace. |
| 16185 | It is very similar to @value{GDBN} trace, except it does not interfere with normal |
| 16186 | program execution and is thus much faster. Hardware breakpoints/watchpoint |
| 16187 | triggers can be set using: |
| 16188 | @table @code |
| 16189 | @item $LEA/$LDATA |
| 16190 | Load effective address/data |
| 16191 | @item $SEA/$SDATA |
| 16192 | Store effective address/data |
| 16193 | @item $AEA/$ADATA |
| 16194 | Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA) |
| 16195 | @item $FETCH |
| 16196 | Fetch data |
| 16197 | @end table |
| 16198 | |
| 16199 | When triggered, it can capture low level data, like: @code{PC}, @code{LSEA}, |
| 16200 | @code{LDATA}, @code{SDATA}, @code{READSPR}, @code{WRITESPR}, @code{INSTR}. |
| 16201 | |
| 16202 | @code{htrace} commands: |
| 16203 | @cindex OpenRISC 1000 htrace |
| 16204 | @table @code |
| 16205 | @kindex hwatch |
| 16206 | @item hwatch @var{conditional} |
| 16207 | Set hardware watchpoint on combination of Load/Store Effective Address(es) |
| 16208 | or Data. For example: |
| 16209 | |
| 16210 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} |
| 16211 | |
| 16212 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} |
| 16213 | |
| 16214 | @kindex htrace |
| 16215 | @item htrace info |
| 16216 | Display information about current HW trace configuration. |
| 16217 | |
| 16218 | @item htrace trigger @var{conditional} |
| 16219 | Set starting criteria for HW trace. |
| 16220 | |
| 16221 | @item htrace qualifier @var{conditional} |
| 16222 | Set acquisition qualifier for HW trace. |
| 16223 | |
| 16224 | @item htrace stop @var{conditional} |
| 16225 | Set HW trace stopping criteria. |
| 16226 | |
| 16227 | @item htrace record [@var{data}]* |
| 16228 | Selects the data to be recorded, when qualifier is met and HW trace was |
| 16229 | triggered. |
| 16230 | |
| 16231 | @item htrace enable |
| 16232 | @itemx htrace disable |
| 16233 | Enables/disables the HW trace. |
| 16234 | |
| 16235 | @item htrace rewind [@var{filename}] |
| 16236 | Clears currently recorded trace data. |
| 16237 | |
| 16238 | If filename is specified, new trace file is made and any newly collected data |
| 16239 | will be written there. |
| 16240 | |
| 16241 | @item htrace print [@var{start} [@var{len}]] |
| 16242 | Prints trace buffer, using current record configuration. |
| 16243 | |
| 16244 | @item htrace mode continuous |
| 16245 | Set continuous trace mode. |
| 16246 | |
| 16247 | @item htrace mode suspend |
| 16248 | Set suspend trace mode. |
| 16249 | |
| 16250 | @end table |
| 16251 | |
| 16252 | @node PowerPC Embedded |
| 16253 | @subsection PowerPC Embedded |
| 16254 | |
| 16255 | @value{GDBN} provides the following PowerPC-specific commands: |
| 16256 | |
| 16257 | @table @code |
| 16258 | @kindex set powerpc |
| 16259 | @item set powerpc soft-float |
| 16260 | @itemx show powerpc soft-float |
| 16261 | Force @value{GDBN} to use (or not use) a software floating point calling |
| 16262 | convention. By default, @value{GDBN} selects the calling convention based |
| 16263 | on the selected architecture and the provided executable file. |
| 16264 | |
| 16265 | @item set powerpc vector-abi |
| 16266 | @itemx show powerpc vector-abi |
| 16267 | Force @value{GDBN} to use the specified calling convention for vector |
| 16268 | arguments and return values. The valid options are @samp{auto}; |
| 16269 | @samp{generic}, to avoid vector registers even if they are present; |
| 16270 | @samp{altivec}, to use AltiVec registers; and @samp{spe} to use SPE |
| 16271 | registers. By default, @value{GDBN} selects the calling convention |
| 16272 | based on the selected architecture and the provided executable file. |
| 16273 | |
| 16274 | @kindex target dink32 |
| 16275 | @item target dink32 @var{dev} |
| 16276 | DINK32 ROM monitor. |
| 16277 | |
| 16278 | @kindex target ppcbug |
| 16279 | @item target ppcbug @var{dev} |
| 16280 | @kindex target ppcbug1 |
| 16281 | @item target ppcbug1 @var{dev} |
| 16282 | PPCBUG ROM monitor for PowerPC. |
| 16283 | |
| 16284 | @kindex target sds |
| 16285 | @item target sds @var{dev} |
| 16286 | SDS monitor, running on a PowerPC board (such as Motorola's ADS). |
| 16287 | @end table |
| 16288 | |
| 16289 | @cindex SDS protocol |
| 16290 | The following commands specific to the SDS protocol are supported |
| 16291 | by @value{GDBN}: |
| 16292 | |
| 16293 | @table @code |
| 16294 | @item set sdstimeout @var{nsec} |
| 16295 | @kindex set sdstimeout |
| 16296 | Set the timeout for SDS protocol reads to be @var{nsec} seconds. The |
| 16297 | default is 2 seconds. |
| 16298 | |
| 16299 | @item show sdstimeout |
| 16300 | @kindex show sdstimeout |
| 16301 | Show the current value of the SDS timeout. |
| 16302 | |
| 16303 | @item sds @var{command} |
| 16304 | @kindex sds@r{, a command} |
| 16305 | Send the specified @var{command} string to the SDS monitor. |
| 16306 | @end table |
| 16307 | |
| 16308 | |
| 16309 | @node PA |
| 16310 | @subsection HP PA Embedded |
| 16311 | |
| 16312 | @table @code |
| 16313 | |
| 16314 | @kindex target op50n |
| 16315 | @item target op50n @var{dev} |
| 16316 | OP50N monitor, running on an OKI HPPA board. |
| 16317 | |
| 16318 | @kindex target w89k |
| 16319 | @item target w89k @var{dev} |
| 16320 | W89K monitor, running on a Winbond HPPA board. |
| 16321 | |
| 16322 | @end table |
| 16323 | |
| 16324 | @node Sparclet |
| 16325 | @subsection Tsqware Sparclet |
| 16326 | |
| 16327 | @cindex Sparclet |
| 16328 | |
| 16329 | @value{GDBN} enables developers to debug tasks running on |
| 16330 | Sparclet targets from a Unix host. |
| 16331 | @value{GDBN} uses code that runs on |
| 16332 | both the Unix host and on the Sparclet target. The program |
| 16333 | @code{@value{GDBP}} is installed and executed on the Unix host. |
| 16334 | |
| 16335 | @table @code |
| 16336 | @item remotetimeout @var{args} |
| 16337 | @kindex remotetimeout |
| 16338 | @value{GDBN} supports the option @code{remotetimeout}. |
| 16339 | This option is set by the user, and @var{args} represents the number of |
| 16340 | seconds @value{GDBN} waits for responses. |
| 16341 | @end table |
| 16342 | |
| 16343 | @cindex compiling, on Sparclet |
| 16344 | When compiling for debugging, include the options @samp{-g} to get debug |
| 16345 | information and @samp{-Ttext} to relocate the program to where you wish to |
| 16346 | load it on the target. You may also want to add the options @samp{-n} or |
| 16347 | @samp{-N} in order to reduce the size of the sections. Example: |
| 16348 | |
| 16349 | @smallexample |
| 16350 | sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N |
| 16351 | @end smallexample |
| 16352 | |
| 16353 | You can use @code{objdump} to verify that the addresses are what you intended: |
| 16354 | |
| 16355 | @smallexample |
| 16356 | sparclet-aout-objdump --headers --syms prog |
| 16357 | @end smallexample |
| 16358 | |
| 16359 | @cindex running, on Sparclet |
| 16360 | Once you have set |
| 16361 | your Unix execution search path to find @value{GDBN}, you are ready to |
| 16362 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} |
| 16363 | (or @code{sparclet-aout-gdb}, depending on your installation). |
| 16364 | |
| 16365 | @value{GDBN} comes up showing the prompt: |
| 16366 | |
| 16367 | @smallexample |
| 16368 | (gdbslet) |
| 16369 | @end smallexample |
| 16370 | |
| 16371 | @menu |
| 16372 | * Sparclet File:: Setting the file to debug |
| 16373 | * Sparclet Connection:: Connecting to Sparclet |
| 16374 | * Sparclet Download:: Sparclet download |
| 16375 | * Sparclet Execution:: Running and debugging |
| 16376 | @end menu |
| 16377 | |
| 16378 | @node Sparclet File |
| 16379 | @subsubsection Setting File to Debug |
| 16380 | |
| 16381 | The @value{GDBN} command @code{file} lets you choose with program to debug. |
| 16382 | |
| 16383 | @smallexample |
| 16384 | (gdbslet) file prog |
| 16385 | @end smallexample |
| 16386 | |
| 16387 | @need 1000 |
| 16388 | @value{GDBN} then attempts to read the symbol table of @file{prog}. |
| 16389 | @value{GDBN} locates |
| 16390 | the file by searching the directories listed in the command search |
| 16391 | path. |
| 16392 | If the file was compiled with debug information (option @samp{-g}), source |
| 16393 | files will be searched as well. |
| 16394 | @value{GDBN} locates |
| 16395 | the source files by searching the directories listed in the directory search |
| 16396 | path (@pxref{Environment, ,Your Program's Environment}). |
| 16397 | If it fails |
| 16398 | to find a file, it displays a message such as: |
| 16399 | |
| 16400 | @smallexample |
| 16401 | prog: No such file or directory. |
| 16402 | @end smallexample |
| 16403 | |
| 16404 | When this happens, add the appropriate directories to the search paths with |
| 16405 | the @value{GDBN} commands @code{path} and @code{dir}, and execute the |
| 16406 | @code{target} command again. |
| 16407 | |
| 16408 | @node Sparclet Connection |
| 16409 | @subsubsection Connecting to Sparclet |
| 16410 | |
| 16411 | The @value{GDBN} command @code{target} lets you connect to a Sparclet target. |
| 16412 | To connect to a target on serial port ``@code{ttya}'', type: |
| 16413 | |
| 16414 | @smallexample |
| 16415 | (gdbslet) target sparclet /dev/ttya |
| 16416 | Remote target sparclet connected to /dev/ttya |
| 16417 | main () at ../prog.c:3 |
| 16418 | @end smallexample |
| 16419 | |
| 16420 | @need 750 |
| 16421 | @value{GDBN} displays messages like these: |
| 16422 | |
| 16423 | @smallexample |
| 16424 | Connected to ttya. |
| 16425 | @end smallexample |
| 16426 | |
| 16427 | @node Sparclet Download |
| 16428 | @subsubsection Sparclet Download |
| 16429 | |
| 16430 | @cindex download to Sparclet |
| 16431 | Once connected to the Sparclet target, |
| 16432 | you can use the @value{GDBN} |
| 16433 | @code{load} command to download the file from the host to the target. |
| 16434 | The file name and load offset should be given as arguments to the @code{load} |
| 16435 | command. |
| 16436 | Since the file format is aout, the program must be loaded to the starting |
| 16437 | address. You can use @code{objdump} to find out what this value is. The load |
| 16438 | offset is an offset which is added to the VMA (virtual memory address) |
| 16439 | of each of the file's sections. |
| 16440 | For instance, if the program |
| 16441 | @file{prog} was linked to text address 0x1201000, with data at 0x12010160 |
| 16442 | and bss at 0x12010170, in @value{GDBN}, type: |
| 16443 | |
| 16444 | @smallexample |
| 16445 | (gdbslet) load prog 0x12010000 |
| 16446 | Loading section .text, size 0xdb0 vma 0x12010000 |
| 16447 | @end smallexample |
| 16448 | |
| 16449 | If the code is loaded at a different address then what the program was linked |
| 16450 | to, you may need to use the @code{section} and @code{add-symbol-file} commands |
| 16451 | to tell @value{GDBN} where to map the symbol table. |
| 16452 | |
| 16453 | @node Sparclet Execution |
| 16454 | @subsubsection Running and Debugging |
| 16455 | |
| 16456 | @cindex running and debugging Sparclet programs |
| 16457 | You can now begin debugging the task using @value{GDBN}'s execution control |
| 16458 | commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN} |
| 16459 | manual for the list of commands. |
| 16460 | |
| 16461 | @smallexample |
| 16462 | (gdbslet) b main |
| 16463 | Breakpoint 1 at 0x12010000: file prog.c, line 3. |
| 16464 | (gdbslet) run |
| 16465 | Starting program: prog |
| 16466 | Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3 |
| 16467 | 3 char *symarg = 0; |
| 16468 | (gdbslet) step |
| 16469 | 4 char *execarg = "hello!"; |
| 16470 | (gdbslet) |
| 16471 | @end smallexample |
| 16472 | |
| 16473 | @node Sparclite |
| 16474 | @subsection Fujitsu Sparclite |
| 16475 | |
| 16476 | @table @code |
| 16477 | |
| 16478 | @kindex target sparclite |
| 16479 | @item target sparclite @var{dev} |
| 16480 | Fujitsu sparclite boards, used only for the purpose of loading. |
| 16481 | You must use an additional command to debug the program. |
| 16482 | For example: target remote @var{dev} using @value{GDBN} standard |
| 16483 | remote protocol. |
| 16484 | |
| 16485 | @end table |
| 16486 | |
| 16487 | @node Z8000 |
| 16488 | @subsection Zilog Z8000 |
| 16489 | |
| 16490 | @cindex Z8000 |
| 16491 | @cindex simulator, Z8000 |
| 16492 | @cindex Zilog Z8000 simulator |
| 16493 | |
| 16494 | When configured for debugging Zilog Z8000 targets, @value{GDBN} includes |
| 16495 | a Z8000 simulator. |
| 16496 | |
| 16497 | For the Z8000 family, @samp{target sim} simulates either the Z8002 (the |
| 16498 | unsegmented variant of the Z8000 architecture) or the Z8001 (the |
| 16499 | segmented variant). The simulator recognizes which architecture is |
| 16500 | appropriate by inspecting the object code. |
| 16501 | |
| 16502 | @table @code |
| 16503 | @item target sim @var{args} |
| 16504 | @kindex sim |
| 16505 | @kindex target sim@r{, with Z8000} |
| 16506 | Debug programs on a simulated CPU. If the simulator supports setup |
| 16507 | options, specify them via @var{args}. |
| 16508 | @end table |
| 16509 | |
| 16510 | @noindent |
| 16511 | After specifying this target, you can debug programs for the simulated |
| 16512 | CPU in the same style as programs for your host computer; use the |
| 16513 | @code{file} command to load a new program image, the @code{run} command |
| 16514 | to run your program, and so on. |
| 16515 | |
| 16516 | As well as making available all the usual machine registers |
| 16517 | (@pxref{Registers, ,Registers}), the Z8000 simulator provides three |
| 16518 | additional items of information as specially named registers: |
| 16519 | |
| 16520 | @table @code |
| 16521 | |
| 16522 | @item cycles |
| 16523 | Counts clock-ticks in the simulator. |
| 16524 | |
| 16525 | @item insts |
| 16526 | Counts instructions run in the simulator. |
| 16527 | |
| 16528 | @item time |
| 16529 | Execution time in 60ths of a second. |
| 16530 | |
| 16531 | @end table |
| 16532 | |
| 16533 | You can refer to these values in @value{GDBN} expressions with the usual |
| 16534 | conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a |
| 16535 | conditional breakpoint that suspends only after at least 5000 |
| 16536 | simulated clock ticks. |
| 16537 | |
| 16538 | @node AVR |
| 16539 | @subsection Atmel AVR |
| 16540 | @cindex AVR |
| 16541 | |
| 16542 | When configured for debugging the Atmel AVR, @value{GDBN} supports the |
| 16543 | following AVR-specific commands: |
| 16544 | |
| 16545 | @table @code |
| 16546 | @item info io_registers |
| 16547 | @kindex info io_registers@r{, AVR} |
| 16548 | @cindex I/O registers (Atmel AVR) |
| 16549 | This command displays information about the AVR I/O registers. For |
| 16550 | each register, @value{GDBN} prints its number and value. |
| 16551 | @end table |
| 16552 | |
| 16553 | @node CRIS |
| 16554 | @subsection CRIS |
| 16555 | @cindex CRIS |
| 16556 | |
| 16557 | When configured for debugging CRIS, @value{GDBN} provides the |
| 16558 | following CRIS-specific commands: |
| 16559 | |
| 16560 | @table @code |
| 16561 | @item set cris-version @var{ver} |
| 16562 | @cindex CRIS version |
| 16563 | Set the current CRIS version to @var{ver}, either @samp{10} or @samp{32}. |
| 16564 | The CRIS version affects register names and sizes. This command is useful in |
| 16565 | case autodetection of the CRIS version fails. |
| 16566 | |
| 16567 | @item show cris-version |
| 16568 | Show the current CRIS version. |
| 16569 | |
| 16570 | @item set cris-dwarf2-cfi |
| 16571 | @cindex DWARF-2 CFI and CRIS |
| 16572 | Set the usage of DWARF-2 CFI for CRIS debugging. The default is @samp{on}. |
| 16573 | Change to @samp{off} when using @code{gcc-cris} whose version is below |
| 16574 | @code{R59}. |
| 16575 | |
| 16576 | @item show cris-dwarf2-cfi |
| 16577 | Show the current state of using DWARF-2 CFI. |
| 16578 | |
| 16579 | @item set cris-mode @var{mode} |
| 16580 | @cindex CRIS mode |
| 16581 | Set the current CRIS mode to @var{mode}. It should only be changed when |
| 16582 | debugging in guru mode, in which case it should be set to |
| 16583 | @samp{guru} (the default is @samp{normal}). |
| 16584 | |
| 16585 | @item show cris-mode |
| 16586 | Show the current CRIS mode. |
| 16587 | @end table |
| 16588 | |
| 16589 | @node Super-H |
| 16590 | @subsection Renesas Super-H |
| 16591 | @cindex Super-H |
| 16592 | |
| 16593 | For the Renesas Super-H processor, @value{GDBN} provides these |
| 16594 | commands: |
| 16595 | |
| 16596 | @table @code |
| 16597 | @item regs |
| 16598 | @kindex regs@r{, Super-H} |
| 16599 | Show the values of all Super-H registers. |
| 16600 | |
| 16601 | @item set sh calling-convention @var{convention} |
| 16602 | @kindex set sh calling-convention |
| 16603 | Set the calling-convention used when calling functions from @value{GDBN}. |
| 16604 | Allowed values are @samp{gcc}, which is the default setting, and @samp{renesas}. |
| 16605 | With the @samp{gcc} setting, functions are called using the @value{NGCC} calling |
| 16606 | convention. If the DWARF-2 information of the called function specifies |
| 16607 | that the function follows the Renesas calling convention, the function |
| 16608 | is called using the Renesas calling convention. If the calling convention |
| 16609 | is set to @samp{renesas}, the Renesas calling convention is always used, |
| 16610 | regardless of the DWARF-2 information. This can be used to override the |
| 16611 | default of @samp{gcc} if debug information is missing, or the compiler |
| 16612 | does not emit the DWARF-2 calling convention entry for a function. |
| 16613 | |
| 16614 | @item show sh calling-convention |
| 16615 | @kindex show sh calling-convention |
| 16616 | Show the current calling convention setting. |
| 16617 | |
| 16618 | @end table |
| 16619 | |
| 16620 | |
| 16621 | @node Architectures |
| 16622 | @section Architectures |
| 16623 | |
| 16624 | This section describes characteristics of architectures that affect |
| 16625 | all uses of @value{GDBN} with the architecture, both native and cross. |
| 16626 | |
| 16627 | @menu |
| 16628 | * i386:: |
| 16629 | * A29K:: |
| 16630 | * Alpha:: |
| 16631 | * MIPS:: |
| 16632 | * HPPA:: HP PA architecture |
| 16633 | * SPU:: Cell Broadband Engine SPU architecture |
| 16634 | * PowerPC:: |
| 16635 | @end menu |
| 16636 | |
| 16637 | @node i386 |
| 16638 | @subsection x86 Architecture-specific Issues |
| 16639 | |
| 16640 | @table @code |
| 16641 | @item set struct-convention @var{mode} |
| 16642 | @kindex set struct-convention |
| 16643 | @cindex struct return convention |
| 16644 | @cindex struct/union returned in registers |
| 16645 | Set the convention used by the inferior to return @code{struct}s and |
| 16646 | @code{union}s from functions to @var{mode}. Possible values of |
| 16647 | @var{mode} are @code{"pcc"}, @code{"reg"}, and @code{"default"} (the |
| 16648 | default). @code{"default"} or @code{"pcc"} means that @code{struct}s |
| 16649 | are returned on the stack, while @code{"reg"} means that a |
| 16650 | @code{struct} or a @code{union} whose size is 1, 2, 4, or 8 bytes will |
| 16651 | be returned in a register. |
| 16652 | |
| 16653 | @item show struct-convention |
| 16654 | @kindex show struct-convention |
| 16655 | Show the current setting of the convention to return @code{struct}s |
| 16656 | from functions. |
| 16657 | @end table |
| 16658 | |
| 16659 | @node A29K |
| 16660 | @subsection A29K |
| 16661 | |
| 16662 | @table @code |
| 16663 | |
| 16664 | @kindex set rstack_high_address |
| 16665 | @cindex AMD 29K register stack |
| 16666 | @cindex register stack, AMD29K |
| 16667 | @item set rstack_high_address @var{address} |
| 16668 | On AMD 29000 family processors, registers are saved in a separate |
| 16669 | @dfn{register stack}. There is no way for @value{GDBN} to determine the |
| 16670 | extent of this stack. Normally, @value{GDBN} just assumes that the |
| 16671 | stack is ``large enough''. This may result in @value{GDBN} referencing |
| 16672 | memory locations that do not exist. If necessary, you can get around |
| 16673 | this problem by specifying the ending address of the register stack with |
| 16674 | the @code{set rstack_high_address} command. The argument should be an |
| 16675 | address, which you probably want to precede with @samp{0x} to specify in |
| 16676 | hexadecimal. |
| 16677 | |
| 16678 | @kindex show rstack_high_address |
| 16679 | @item show rstack_high_address |
| 16680 | Display the current limit of the register stack, on AMD 29000 family |
| 16681 | processors. |
| 16682 | |
| 16683 | @end table |
| 16684 | |
| 16685 | @node Alpha |
| 16686 | @subsection Alpha |
| 16687 | |
| 16688 | See the following section. |
| 16689 | |
| 16690 | @node MIPS |
| 16691 | @subsection MIPS |
| 16692 | |
| 16693 | @cindex stack on Alpha |
| 16694 | @cindex stack on MIPS |
| 16695 | @cindex Alpha stack |
| 16696 | @cindex MIPS stack |
| 16697 | Alpha- and MIPS-based computers use an unusual stack frame, which |
| 16698 | sometimes requires @value{GDBN} to search backward in the object code to |
| 16699 | find the beginning of a function. |
| 16700 | |
| 16701 | @cindex response time, MIPS debugging |
| 16702 | To improve response time (especially for embedded applications, where |
| 16703 | @value{GDBN} may be restricted to a slow serial line for this search) |
| 16704 | you may want to limit the size of this search, using one of these |
| 16705 | commands: |
| 16706 | |
| 16707 | @table @code |
| 16708 | @cindex @code{heuristic-fence-post} (Alpha, MIPS) |
| 16709 | @item set heuristic-fence-post @var{limit} |
| 16710 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its |
| 16711 | search for the beginning of a function. A value of @var{0} (the |
| 16712 | default) means there is no limit. However, except for @var{0}, the |
| 16713 | larger the limit the more bytes @code{heuristic-fence-post} must search |
| 16714 | and therefore the longer it takes to run. You should only need to use |
| 16715 | this command when debugging a stripped executable. |
| 16716 | |
| 16717 | @item show heuristic-fence-post |
| 16718 | Display the current limit. |
| 16719 | @end table |
| 16720 | |
| 16721 | @noindent |
| 16722 | These commands are available @emph{only} when @value{GDBN} is configured |
| 16723 | for debugging programs on Alpha or MIPS processors. |
| 16724 | |
| 16725 | Several MIPS-specific commands are available when debugging MIPS |
| 16726 | programs: |
| 16727 | |
| 16728 | @table @code |
| 16729 | @item set mips abi @var{arg} |
| 16730 | @kindex set mips abi |
| 16731 | @cindex set ABI for MIPS |
| 16732 | Tell @value{GDBN} which MIPS ABI is used by the inferior. Possible |
| 16733 | values of @var{arg} are: |
| 16734 | |
| 16735 | @table @samp |
| 16736 | @item auto |
| 16737 | The default ABI associated with the current binary (this is the |
| 16738 | default). |
| 16739 | @item o32 |
| 16740 | @item o64 |
| 16741 | @item n32 |
| 16742 | @item n64 |
| 16743 | @item eabi32 |
| 16744 | @item eabi64 |
| 16745 | @item auto |
| 16746 | @end table |
| 16747 | |
| 16748 | @item show mips abi |
| 16749 | @kindex show mips abi |
| 16750 | Show the MIPS ABI used by @value{GDBN} to debug the inferior. |
| 16751 | |
| 16752 | @item set mipsfpu |
| 16753 | @itemx show mipsfpu |
| 16754 | @xref{MIPS Embedded, set mipsfpu}. |
| 16755 | |
| 16756 | @item set mips mask-address @var{arg} |
| 16757 | @kindex set mips mask-address |
| 16758 | @cindex MIPS addresses, masking |
| 16759 | This command determines whether the most-significant 32 bits of 64-bit |
| 16760 | MIPS addresses are masked off. The argument @var{arg} can be |
| 16761 | @samp{on}, @samp{off}, or @samp{auto}. The latter is the default |
| 16762 | setting, which lets @value{GDBN} determine the correct value. |
| 16763 | |
| 16764 | @item show mips mask-address |
| 16765 | @kindex show mips mask-address |
| 16766 | Show whether the upper 32 bits of MIPS addresses are masked off or |
| 16767 | not. |
| 16768 | |
| 16769 | @item set remote-mips64-transfers-32bit-regs |
| 16770 | @kindex set remote-mips64-transfers-32bit-regs |
| 16771 | This command controls compatibility with 64-bit MIPS targets that |
| 16772 | transfer data in 32-bit quantities. If you have an old MIPS 64 target |
| 16773 | that transfers 32 bits for some registers, like @sc{sr} and @sc{fsr}, |
| 16774 | and 64 bits for other registers, set this option to @samp{on}. |
| 16775 | |
| 16776 | @item show remote-mips64-transfers-32bit-regs |
| 16777 | @kindex show remote-mips64-transfers-32bit-regs |
| 16778 | Show the current setting of compatibility with older MIPS 64 targets. |
| 16779 | |
| 16780 | @item set debug mips |
| 16781 | @kindex set debug mips |
| 16782 | This command turns on and off debugging messages for the MIPS-specific |
| 16783 | target code in @value{GDBN}. |
| 16784 | |
| 16785 | @item show debug mips |
| 16786 | @kindex show debug mips |
| 16787 | Show the current setting of MIPS debugging messages. |
| 16788 | @end table |
| 16789 | |
| 16790 | |
| 16791 | @node HPPA |
| 16792 | @subsection HPPA |
| 16793 | @cindex HPPA support |
| 16794 | |
| 16795 | When @value{GDBN} is debugging the HP PA architecture, it provides the |
| 16796 | following special commands: |
| 16797 | |
| 16798 | @table @code |
| 16799 | @item set debug hppa |
| 16800 | @kindex set debug hppa |
| 16801 | This command determines whether HPPA architecture-specific debugging |
| 16802 | messages are to be displayed. |
| 16803 | |
| 16804 | @item show debug hppa |
| 16805 | Show whether HPPA debugging messages are displayed. |
| 16806 | |
| 16807 | @item maint print unwind @var{address} |
| 16808 | @kindex maint print unwind@r{, HPPA} |
| 16809 | This command displays the contents of the unwind table entry at the |
| 16810 | given @var{address}. |
| 16811 | |
| 16812 | @end table |
| 16813 | |
| 16814 | |
| 16815 | @node SPU |
| 16816 | @subsection Cell Broadband Engine SPU architecture |
| 16817 | @cindex Cell Broadband Engine |
| 16818 | @cindex SPU |
| 16819 | |
| 16820 | When @value{GDBN} is debugging the Cell Broadband Engine SPU architecture, |
| 16821 | it provides the following special commands: |
| 16822 | |
| 16823 | @table @code |
| 16824 | @item info spu event |
| 16825 | @kindex info spu |
| 16826 | Display SPU event facility status. Shows current event mask |
| 16827 | and pending event status. |
| 16828 | |
| 16829 | @item info spu signal |
| 16830 | Display SPU signal notification facility status. Shows pending |
| 16831 | signal-control word and signal notification mode of both signal |
| 16832 | notification channels. |
| 16833 | |
| 16834 | @item info spu mailbox |
| 16835 | Display SPU mailbox facility status. Shows all pending entries, |
| 16836 | in order of processing, in each of the SPU Write Outbound, |
| 16837 | SPU Write Outbound Interrupt, and SPU Read Inbound mailboxes. |
| 16838 | |
| 16839 | @item info spu dma |
| 16840 | Display MFC DMA status. Shows all pending commands in the MFC |
| 16841 | DMA queue. For each entry, opcode, tag, class IDs, effective |
| 16842 | and local store addresses and transfer size are shown. |
| 16843 | |
| 16844 | @item info spu proxydma |
| 16845 | Display MFC Proxy-DMA status. Shows all pending commands in the MFC |
| 16846 | Proxy-DMA queue. For each entry, opcode, tag, class IDs, effective |
| 16847 | and local store addresses and transfer size are shown. |
| 16848 | |
| 16849 | @end table |
| 16850 | |
| 16851 | @node PowerPC |
| 16852 | @subsection PowerPC |
| 16853 | @cindex PowerPC architecture |
| 16854 | |
| 16855 | When @value{GDBN} is debugging the PowerPC architecture, it provides a set of |
| 16856 | pseudo-registers to enable inspection of 128-bit wide Decimal Floating Point |
| 16857 | numbers stored in the floating point registers. These values must be stored |
| 16858 | in two consecutive registers, always starting at an even register like |
| 16859 | @code{f0} or @code{f2}. |
| 16860 | |
| 16861 | The pseudo-registers go from @code{$dl0} through @code{$dl15}, and are formed |
| 16862 | by joining the even/odd register pairs @code{f0} and @code{f1} for @code{$dl0}, |
| 16863 | @code{f2} and @code{f3} for @code{$dl1} and so on. |
| 16864 | |
| 16865 | For POWER7 processors, @value{GDBN} provides a set of pseudo-registers, the 64-bit |
| 16866 | wide Extended Floating Point Registers (@samp{f32} through @samp{f63}). |
| 16867 | |
| 16868 | |
| 16869 | @node Controlling GDB |
| 16870 | @chapter Controlling @value{GDBN} |
| 16871 | |
| 16872 | You can alter the way @value{GDBN} interacts with you by using the |
| 16873 | @code{set} command. For commands controlling how @value{GDBN} displays |
| 16874 | data, see @ref{Print Settings, ,Print Settings}. Other settings are |
| 16875 | described here. |
| 16876 | |
| 16877 | @menu |
| 16878 | * Prompt:: Prompt |
| 16879 | * Editing:: Command editing |
| 16880 | * Command History:: Command history |
| 16881 | * Screen Size:: Screen size |
| 16882 | * Numbers:: Numbers |
| 16883 | * ABI:: Configuring the current ABI |
| 16884 | * Messages/Warnings:: Optional warnings and messages |
| 16885 | * Debugging Output:: Optional messages about internal happenings |
| 16886 | @end menu |
| 16887 | |
| 16888 | @node Prompt |
| 16889 | @section Prompt |
| 16890 | |
| 16891 | @cindex prompt |
| 16892 | |
| 16893 | @value{GDBN} indicates its readiness to read a command by printing a string |
| 16894 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You |
| 16895 | can change the prompt string with the @code{set prompt} command. For |
| 16896 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change |
| 16897 | the prompt in one of the @value{GDBN} sessions so that you can always tell |
| 16898 | which one you are talking to. |
| 16899 | |
| 16900 | @emph{Note:} @code{set prompt} does not add a space for you after the |
| 16901 | prompt you set. This allows you to set a prompt which ends in a space |
| 16902 | or a prompt that does not. |
| 16903 | |
| 16904 | @table @code |
| 16905 | @kindex set prompt |
| 16906 | @item set prompt @var{newprompt} |
| 16907 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. |
| 16908 | |
| 16909 | @kindex show prompt |
| 16910 | @item show prompt |
| 16911 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} |
| 16912 | @end table |
| 16913 | |
| 16914 | @node Editing |
| 16915 | @section Command Editing |
| 16916 | @cindex readline |
| 16917 | @cindex command line editing |
| 16918 | |
| 16919 | @value{GDBN} reads its input commands via the @dfn{Readline} interface. This |
| 16920 | @sc{gnu} library provides consistent behavior for programs which provide a |
| 16921 | command line interface to the user. Advantages are @sc{gnu} Emacs-style |
| 16922 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history |
| 16923 | substitution, and a storage and recall of command history across |
| 16924 | debugging sessions. |
| 16925 | |
| 16926 | You may control the behavior of command line editing in @value{GDBN} with the |
| 16927 | command @code{set}. |
| 16928 | |
| 16929 | @table @code |
| 16930 | @kindex set editing |
| 16931 | @cindex editing |
| 16932 | @item set editing |
| 16933 | @itemx set editing on |
| 16934 | Enable command line editing (enabled by default). |
| 16935 | |
| 16936 | @item set editing off |
| 16937 | Disable command line editing. |
| 16938 | |
| 16939 | @kindex show editing |
| 16940 | @item show editing |
| 16941 | Show whether command line editing is enabled. |
| 16942 | @end table |
| 16943 | |
| 16944 | @xref{Command Line Editing}, for more details about the Readline |
| 16945 | interface. Users unfamiliar with @sc{gnu} Emacs or @code{vi} are |
| 16946 | encouraged to read that chapter. |
| 16947 | |
| 16948 | @node Command History |
| 16949 | @section Command History |
| 16950 | @cindex command history |
| 16951 | |
| 16952 | @value{GDBN} can keep track of the commands you type during your |
| 16953 | debugging sessions, so that you can be certain of precisely what |
| 16954 | happened. Use these commands to manage the @value{GDBN} command |
| 16955 | history facility. |
| 16956 | |
| 16957 | @value{GDBN} uses the @sc{gnu} History library, a part of the Readline |
| 16958 | package, to provide the history facility. @xref{Using History |
| 16959 | Interactively}, for the detailed description of the History library. |
| 16960 | |
| 16961 | To issue a command to @value{GDBN} without affecting certain aspects of |
| 16962 | the state which is seen by users, prefix it with @samp{server } |
| 16963 | (@pxref{Server Prefix}). This |
| 16964 | means that this command will not affect the command history, nor will it |
| 16965 | affect @value{GDBN}'s notion of which command to repeat if @key{RET} is |
| 16966 | pressed on a line by itself. |
| 16967 | |
| 16968 | @cindex @code{server}, command prefix |
| 16969 | The server prefix does not affect the recording of values into the value |
| 16970 | history; to print a value without recording it into the value history, |
| 16971 | use the @code{output} command instead of the @code{print} command. |
| 16972 | |
| 16973 | Here is the description of @value{GDBN} commands related to command |
| 16974 | history. |
| 16975 | |
| 16976 | @table @code |
| 16977 | @cindex history substitution |
| 16978 | @cindex history file |
| 16979 | @kindex set history filename |
| 16980 | @cindex @env{GDBHISTFILE}, environment variable |
| 16981 | @item set history filename @var{fname} |
| 16982 | Set the name of the @value{GDBN} command history file to @var{fname}. |
| 16983 | This is the file where @value{GDBN} reads an initial command history |
| 16984 | list, and where it writes the command history from this session when it |
| 16985 | exits. You can access this list through history expansion or through |
| 16986 | the history command editing characters listed below. This file defaults |
| 16987 | to the value of the environment variable @code{GDBHISTFILE}, or to |
| 16988 | @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable |
| 16989 | is not set. |
| 16990 | |
| 16991 | @cindex save command history |
| 16992 | @kindex set history save |
| 16993 | @item set history save |
| 16994 | @itemx set history save on |
| 16995 | Record command history in a file, whose name may be specified with the |
| 16996 | @code{set history filename} command. By default, this option is disabled. |
| 16997 | |
| 16998 | @item set history save off |
| 16999 | Stop recording command history in a file. |
| 17000 | |
| 17001 | @cindex history size |
| 17002 | @kindex set history size |
| 17003 | @cindex @env{HISTSIZE}, environment variable |
| 17004 | @item set history size @var{size} |
| 17005 | Set the number of commands which @value{GDBN} keeps in its history list. |
| 17006 | This defaults to the value of the environment variable |
| 17007 | @code{HISTSIZE}, or to 256 if this variable is not set. |
| 17008 | @end table |
| 17009 | |
| 17010 | History expansion assigns special meaning to the character @kbd{!}. |
| 17011 | @xref{Event Designators}, for more details. |
| 17012 | |
| 17013 | @cindex history expansion, turn on/off |
| 17014 | Since @kbd{!} is also the logical not operator in C, history expansion |
| 17015 | is off by default. If you decide to enable history expansion with the |
| 17016 | @code{set history expansion on} command, you may sometimes need to |
| 17017 | follow @kbd{!} (when it is used as logical not, in an expression) with |
| 17018 | a space or a tab to prevent it from being expanded. The readline |
| 17019 | history facilities do not attempt substitution on the strings |
| 17020 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. |
| 17021 | |
| 17022 | The commands to control history expansion are: |
| 17023 | |
| 17024 | @table @code |
| 17025 | @item set history expansion on |
| 17026 | @itemx set history expansion |
| 17027 | @kindex set history expansion |
| 17028 | Enable history expansion. History expansion is off by default. |
| 17029 | |
| 17030 | @item set history expansion off |
| 17031 | Disable history expansion. |
| 17032 | |
| 17033 | @c @group |
| 17034 | @kindex show history |
| 17035 | @item show history |
| 17036 | @itemx show history filename |
| 17037 | @itemx show history save |
| 17038 | @itemx show history size |
| 17039 | @itemx show history expansion |
| 17040 | These commands display the state of the @value{GDBN} history parameters. |
| 17041 | @code{show history} by itself displays all four states. |
| 17042 | @c @end group |
| 17043 | @end table |
| 17044 | |
| 17045 | @table @code |
| 17046 | @kindex show commands |
| 17047 | @cindex show last commands |
| 17048 | @cindex display command history |
| 17049 | @item show commands |
| 17050 | Display the last ten commands in the command history. |
| 17051 | |
| 17052 | @item show commands @var{n} |
| 17053 | Print ten commands centered on command number @var{n}. |
| 17054 | |
| 17055 | @item show commands + |
| 17056 | Print ten commands just after the commands last printed. |
| 17057 | @end table |
| 17058 | |
| 17059 | @node Screen Size |
| 17060 | @section Screen Size |
| 17061 | @cindex size of screen |
| 17062 | @cindex pauses in output |
| 17063 | |
| 17064 | Certain commands to @value{GDBN} may produce large amounts of |
| 17065 | information output to the screen. To help you read all of it, |
| 17066 | @value{GDBN} pauses and asks you for input at the end of each page of |
| 17067 | output. Type @key{RET} when you want to continue the output, or @kbd{q} |
| 17068 | to discard the remaining output. Also, the screen width setting |
| 17069 | determines when to wrap lines of output. Depending on what is being |
| 17070 | printed, @value{GDBN} tries to break the line at a readable place, |
| 17071 | rather than simply letting it overflow onto the following line. |
| 17072 | |
| 17073 | Normally @value{GDBN} knows the size of the screen from the terminal |
| 17074 | driver software. For example, on Unix @value{GDBN} uses the termcap data base |
| 17075 | together with the value of the @code{TERM} environment variable and the |
| 17076 | @code{stty rows} and @code{stty cols} settings. If this is not correct, |
| 17077 | you can override it with the @code{set height} and @code{set |
| 17078 | width} commands: |
| 17079 | |
| 17080 | @table @code |
| 17081 | @kindex set height |
| 17082 | @kindex set width |
| 17083 | @kindex show width |
| 17084 | @kindex show height |
| 17085 | @item set height @var{lpp} |
| 17086 | @itemx show height |
| 17087 | @itemx set width @var{cpl} |
| 17088 | @itemx show width |
| 17089 | These @code{set} commands specify a screen height of @var{lpp} lines and |
| 17090 | a screen width of @var{cpl} characters. The associated @code{show} |
| 17091 | commands display the current settings. |
| 17092 | |
| 17093 | If you specify a height of zero lines, @value{GDBN} does not pause during |
| 17094 | output no matter how long the output is. This is useful if output is to a |
| 17095 | file or to an editor buffer. |
| 17096 | |
| 17097 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} |
| 17098 | from wrapping its output. |
| 17099 | |
| 17100 | @item set pagination on |
| 17101 | @itemx set pagination off |
| 17102 | @kindex set pagination |
| 17103 | Turn the output pagination on or off; the default is on. Turning |
| 17104 | pagination off is the alternative to @code{set height 0}. |
| 17105 | |
| 17106 | @item show pagination |
| 17107 | @kindex show pagination |
| 17108 | Show the current pagination mode. |
| 17109 | @end table |
| 17110 | |
| 17111 | @node Numbers |
| 17112 | @section Numbers |
| 17113 | @cindex number representation |
| 17114 | @cindex entering numbers |
| 17115 | |
| 17116 | You can always enter numbers in octal, decimal, or hexadecimal in |
| 17117 | @value{GDBN} by the usual conventions: octal numbers begin with |
| 17118 | @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers |
| 17119 | begin with @samp{0x}. Numbers that neither begin with @samp{0} or |
| 17120 | @samp{0x}, nor end with a @samp{.} are, by default, entered in base |
| 17121 | 10; likewise, the default display for numbers---when no particular |
| 17122 | format is specified---is base 10. You can change the default base for |
| 17123 | both input and output with the commands described below. |
| 17124 | |
| 17125 | @table @code |
| 17126 | @kindex set input-radix |
| 17127 | @item set input-radix @var{base} |
| 17128 | Set the default base for numeric input. Supported choices |
| 17129 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be |
| 17130 | specified either unambiguously or using the current input radix; for |
| 17131 | example, any of |
| 17132 | |
| 17133 | @smallexample |
| 17134 | set input-radix 012 |
| 17135 | set input-radix 10. |
| 17136 | set input-radix 0xa |
| 17137 | @end smallexample |
| 17138 | |
| 17139 | @noindent |
| 17140 | sets the input base to decimal. On the other hand, @samp{set input-radix 10} |
| 17141 | leaves the input radix unchanged, no matter what it was, since |
| 17142 | @samp{10}, being without any leading or trailing signs of its base, is |
| 17143 | interpreted in the current radix. Thus, if the current radix is 16, |
| 17144 | @samp{10} is interpreted in hex, i.e.@: as 16 decimal, which doesn't |
| 17145 | change the radix. |
| 17146 | |
| 17147 | @kindex set output-radix |
| 17148 | @item set output-radix @var{base} |
| 17149 | Set the default base for numeric display. Supported choices |
| 17150 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be |
| 17151 | specified either unambiguously or using the current input radix. |
| 17152 | |
| 17153 | @kindex show input-radix |
| 17154 | @item show input-radix |
| 17155 | Display the current default base for numeric input. |
| 17156 | |
| 17157 | @kindex show output-radix |
| 17158 | @item show output-radix |
| 17159 | Display the current default base for numeric display. |
| 17160 | |
| 17161 | @item set radix @r{[}@var{base}@r{]} |
| 17162 | @itemx show radix |
| 17163 | @kindex set radix |
| 17164 | @kindex show radix |
| 17165 | These commands set and show the default base for both input and output |
| 17166 | of numbers. @code{set radix} sets the radix of input and output to |
| 17167 | the same base; without an argument, it resets the radix back to its |
| 17168 | default value of 10. |
| 17169 | |
| 17170 | @end table |
| 17171 | |
| 17172 | @node ABI |
| 17173 | @section Configuring the Current ABI |
| 17174 | |
| 17175 | @value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your |
| 17176 | application automatically. However, sometimes you need to override its |
| 17177 | conclusions. Use these commands to manage @value{GDBN}'s view of the |
| 17178 | current ABI. |
| 17179 | |
| 17180 | @cindex OS ABI |
| 17181 | @kindex set osabi |
| 17182 | @kindex show osabi |
| 17183 | |
| 17184 | One @value{GDBN} configuration can debug binaries for multiple operating |
| 17185 | system targets, either via remote debugging or native emulation. |
| 17186 | @value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use, |
| 17187 | but you can override its conclusion using the @code{set osabi} command. |
| 17188 | One example where this is useful is in debugging of binaries which use |
| 17189 | an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does |
| 17190 | not have the same identifying marks that the standard C library for your |
| 17191 | platform provides. |
| 17192 | |
| 17193 | @table @code |
| 17194 | @item show osabi |
| 17195 | Show the OS ABI currently in use. |
| 17196 | |
| 17197 | @item set osabi |
| 17198 | With no argument, show the list of registered available OS ABI's. |
| 17199 | |
| 17200 | @item set osabi @var{abi} |
| 17201 | Set the current OS ABI to @var{abi}. |
| 17202 | @end table |
| 17203 | |
| 17204 | @cindex float promotion |
| 17205 | |
| 17206 | Generally, the way that an argument of type @code{float} is passed to a |
| 17207 | function depends on whether the function is prototyped. For a prototyped |
| 17208 | (i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged, |
| 17209 | according to the architecture's convention for @code{float}. For unprototyped |
| 17210 | (i.e.@: K&R style) functions, @code{float} arguments are first promoted to type |
| 17211 | @code{double} and then passed. |
| 17212 | |
| 17213 | Unfortunately, some forms of debug information do not reliably indicate whether |
| 17214 | a function is prototyped. If @value{GDBN} calls a function that is not marked |
| 17215 | as prototyped, it consults @kbd{set coerce-float-to-double}. |
| 17216 | |
| 17217 | @table @code |
| 17218 | @kindex set coerce-float-to-double |
| 17219 | @item set coerce-float-to-double |
| 17220 | @itemx set coerce-float-to-double on |
| 17221 | Arguments of type @code{float} will be promoted to @code{double} when passed |
| 17222 | to an unprototyped function. This is the default setting. |
| 17223 | |
| 17224 | @item set coerce-float-to-double off |
| 17225 | Arguments of type @code{float} will be passed directly to unprototyped |
| 17226 | functions. |
| 17227 | |
| 17228 | @kindex show coerce-float-to-double |
| 17229 | @item show coerce-float-to-double |
| 17230 | Show the current setting of promoting @code{float} to @code{double}. |
| 17231 | @end table |
| 17232 | |
| 17233 | @kindex set cp-abi |
| 17234 | @kindex show cp-abi |
| 17235 | @value{GDBN} needs to know the ABI used for your program's C@t{++} |
| 17236 | objects. The correct C@t{++} ABI depends on which C@t{++} compiler was |
| 17237 | used to build your application. @value{GDBN} only fully supports |
| 17238 | programs with a single C@t{++} ABI; if your program contains code using |
| 17239 | multiple C@t{++} ABI's or if @value{GDBN} can not identify your |
| 17240 | program's ABI correctly, you can tell @value{GDBN} which ABI to use. |
| 17241 | Currently supported ABI's include ``gnu-v2'', for @code{g++} versions |
| 17242 | before 3.0, ``gnu-v3'', for @code{g++} versions 3.0 and later, and |
| 17243 | ``hpaCC'' for the HP ANSI C@t{++} compiler. Other C@t{++} compilers may |
| 17244 | use the ``gnu-v2'' or ``gnu-v3'' ABI's as well. The default setting is |
| 17245 | ``auto''. |
| 17246 | |
| 17247 | @table @code |
| 17248 | @item show cp-abi |
| 17249 | Show the C@t{++} ABI currently in use. |
| 17250 | |
| 17251 | @item set cp-abi |
| 17252 | With no argument, show the list of supported C@t{++} ABI's. |
| 17253 | |
| 17254 | @item set cp-abi @var{abi} |
| 17255 | @itemx set cp-abi auto |
| 17256 | Set the current C@t{++} ABI to @var{abi}, or return to automatic detection. |
| 17257 | @end table |
| 17258 | |
| 17259 | @node Messages/Warnings |
| 17260 | @section Optional Warnings and Messages |
| 17261 | |
| 17262 | @cindex verbose operation |
| 17263 | @cindex optional warnings |
| 17264 | By default, @value{GDBN} is silent about its inner workings. If you are |
| 17265 | running on a slow machine, you may want to use the @code{set verbose} |
| 17266 | command. This makes @value{GDBN} tell you when it does a lengthy |
| 17267 | internal operation, so you will not think it has crashed. |
| 17268 | |
| 17269 | Currently, the messages controlled by @code{set verbose} are those |
| 17270 | which announce that the symbol table for a source file is being read; |
| 17271 | see @code{symbol-file} in @ref{Files, ,Commands to Specify Files}. |
| 17272 | |
| 17273 | @table @code |
| 17274 | @kindex set verbose |
| 17275 | @item set verbose on |
| 17276 | Enables @value{GDBN} output of certain informational messages. |
| 17277 | |
| 17278 | @item set verbose off |
| 17279 | Disables @value{GDBN} output of certain informational messages. |
| 17280 | |
| 17281 | @kindex show verbose |
| 17282 | @item show verbose |
| 17283 | Displays whether @code{set verbose} is on or off. |
| 17284 | @end table |
| 17285 | |
| 17286 | By default, if @value{GDBN} encounters bugs in the symbol table of an |
| 17287 | object file, it is silent; but if you are debugging a compiler, you may |
| 17288 | find this information useful (@pxref{Symbol Errors, ,Errors Reading |
| 17289 | Symbol Files}). |
| 17290 | |
| 17291 | @table @code |
| 17292 | |
| 17293 | @kindex set complaints |
| 17294 | @item set complaints @var{limit} |
| 17295 | Permits @value{GDBN} to output @var{limit} complaints about each type of |
| 17296 | unusual symbols before becoming silent about the problem. Set |
| 17297 | @var{limit} to zero to suppress all complaints; set it to a large number |
| 17298 | to prevent complaints from being suppressed. |
| 17299 | |
| 17300 | @kindex show complaints |
| 17301 | @item show complaints |
| 17302 | Displays how many symbol complaints @value{GDBN} is permitted to produce. |
| 17303 | |
| 17304 | @end table |
| 17305 | |
| 17306 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a |
| 17307 | lot of stupid questions to confirm certain commands. For example, if |
| 17308 | you try to run a program which is already running: |
| 17309 | |
| 17310 | @smallexample |
| 17311 | (@value{GDBP}) run |
| 17312 | The program being debugged has been started already. |
| 17313 | Start it from the beginning? (y or n) |
| 17314 | @end smallexample |
| 17315 | |
| 17316 | If you are willing to unflinchingly face the consequences of your own |
| 17317 | commands, you can disable this ``feature'': |
| 17318 | |
| 17319 | @table @code |
| 17320 | |
| 17321 | @kindex set confirm |
| 17322 | @cindex flinching |
| 17323 | @cindex confirmation |
| 17324 | @cindex stupid questions |
| 17325 | @item set confirm off |
| 17326 | Disables confirmation requests. |
| 17327 | |
| 17328 | @item set confirm on |
| 17329 | Enables confirmation requests (the default). |
| 17330 | |
| 17331 | @kindex show confirm |
| 17332 | @item show confirm |
| 17333 | Displays state of confirmation requests. |
| 17334 | |
| 17335 | @end table |
| 17336 | |
| 17337 | @cindex command tracing |
| 17338 | If you need to debug user-defined commands or sourced files you may find it |
| 17339 | useful to enable @dfn{command tracing}. In this mode each command will be |
| 17340 | printed as it is executed, prefixed with one or more @samp{+} symbols, the |
| 17341 | quantity denoting the call depth of each command. |
| 17342 | |
| 17343 | @table @code |
| 17344 | @kindex set trace-commands |
| 17345 | @cindex command scripts, debugging |
| 17346 | @item set trace-commands on |
| 17347 | Enable command tracing. |
| 17348 | @item set trace-commands off |
| 17349 | Disable command tracing. |
| 17350 | @item show trace-commands |
| 17351 | Display the current state of command tracing. |
| 17352 | @end table |
| 17353 | |
| 17354 | @node Debugging Output |
| 17355 | @section Optional Messages about Internal Happenings |
| 17356 | @cindex optional debugging messages |
| 17357 | |
| 17358 | @value{GDBN} has commands that enable optional debugging messages from |
| 17359 | various @value{GDBN} subsystems; normally these commands are of |
| 17360 | interest to @value{GDBN} maintainers, or when reporting a bug. This |
| 17361 | section documents those commands. |
| 17362 | |
| 17363 | @table @code |
| 17364 | @kindex set exec-done-display |
| 17365 | @item set exec-done-display |
| 17366 | Turns on or off the notification of asynchronous commands' |
| 17367 | completion. When on, @value{GDBN} will print a message when an |
| 17368 | asynchronous command finishes its execution. The default is off. |
| 17369 | @kindex show exec-done-display |
| 17370 | @item show exec-done-display |
| 17371 | Displays the current setting of asynchronous command completion |
| 17372 | notification. |
| 17373 | @kindex set debug |
| 17374 | @cindex gdbarch debugging info |
| 17375 | @cindex architecture debugging info |
| 17376 | @item set debug arch |
| 17377 | Turns on or off display of gdbarch debugging info. The default is off |
| 17378 | @kindex show debug |
| 17379 | @item show debug arch |
| 17380 | Displays the current state of displaying gdbarch debugging info. |
| 17381 | @item set debug aix-thread |
| 17382 | @cindex AIX threads |
| 17383 | Display debugging messages about inner workings of the AIX thread |
| 17384 | module. |
| 17385 | @item show debug aix-thread |
| 17386 | Show the current state of AIX thread debugging info display. |
| 17387 | @item set debug dwarf2-die |
| 17388 | @cindex DWARF2 DIEs |
| 17389 | Dump DWARF2 DIEs after they are read in. |
| 17390 | The value is the number of nesting levels to print. |
| 17391 | A value of zero turns off the display. |
| 17392 | @item show debug dwarf2-die |
| 17393 | Show the current state of DWARF2 DIE debugging. |
| 17394 | @item set debug displaced |
| 17395 | @cindex displaced stepping debugging info |
| 17396 | Turns on or off display of @value{GDBN} debugging info for the |
| 17397 | displaced stepping support. The default is off. |
| 17398 | @item show debug displaced |
| 17399 | Displays the current state of displaying @value{GDBN} debugging info |
| 17400 | related to displaced stepping. |
| 17401 | @item set debug event |
| 17402 | @cindex event debugging info |
| 17403 | Turns on or off display of @value{GDBN} event debugging info. The |
| 17404 | default is off. |
| 17405 | @item show debug event |
| 17406 | Displays the current state of displaying @value{GDBN} event debugging |
| 17407 | info. |
| 17408 | @item set debug expression |
| 17409 | @cindex expression debugging info |
| 17410 | Turns on or off display of debugging info about @value{GDBN} |
| 17411 | expression parsing. The default is off. |
| 17412 | @item show debug expression |
| 17413 | Displays the current state of displaying debugging info about |
| 17414 | @value{GDBN} expression parsing. |
| 17415 | @item set debug frame |
| 17416 | @cindex frame debugging info |
| 17417 | Turns on or off display of @value{GDBN} frame debugging info. The |
| 17418 | default is off. |
| 17419 | @item show debug frame |
| 17420 | Displays the current state of displaying @value{GDBN} frame debugging |
| 17421 | info. |
| 17422 | @item set debug infrun |
| 17423 | @cindex inferior debugging info |
| 17424 | Turns on or off display of @value{GDBN} debugging info for running the inferior. |
| 17425 | The default is off. @file{infrun.c} contains GDB's runtime state machine used |
| 17426 | for implementing operations such as single-stepping the inferior. |
| 17427 | @item show debug infrun |
| 17428 | Displays the current state of @value{GDBN} inferior debugging. |
| 17429 | @item set debug lin-lwp |
| 17430 | @cindex @sc{gnu}/Linux LWP debug messages |
| 17431 | @cindex Linux lightweight processes |
| 17432 | Turns on or off debugging messages from the Linux LWP debug support. |
| 17433 | @item show debug lin-lwp |
| 17434 | Show the current state of Linux LWP debugging messages. |
| 17435 | @item set debug lin-lwp-async |
| 17436 | @cindex @sc{gnu}/Linux LWP async debug messages |
| 17437 | @cindex Linux lightweight processes |
| 17438 | Turns on or off debugging messages from the Linux LWP async debug support. |
| 17439 | @item show debug lin-lwp-async |
| 17440 | Show the current state of Linux LWP async debugging messages. |
| 17441 | @item set debug observer |
| 17442 | @cindex observer debugging info |
| 17443 | Turns on or off display of @value{GDBN} observer debugging. This |
| 17444 | includes info such as the notification of observable events. |
| 17445 | @item show debug observer |
| 17446 | Displays the current state of observer debugging. |
| 17447 | @item set debug overload |
| 17448 | @cindex C@t{++} overload debugging info |
| 17449 | Turns on or off display of @value{GDBN} C@t{++} overload debugging |
| 17450 | info. This includes info such as ranking of functions, etc. The default |
| 17451 | is off. |
| 17452 | @item show debug overload |
| 17453 | Displays the current state of displaying @value{GDBN} C@t{++} overload |
| 17454 | debugging info. |
| 17455 | @cindex packets, reporting on stdout |
| 17456 | @cindex serial connections, debugging |
| 17457 | @cindex debug remote protocol |
| 17458 | @cindex remote protocol debugging |
| 17459 | @cindex display remote packets |
| 17460 | @item set debug remote |
| 17461 | Turns on or off display of reports on all packets sent back and forth across |
| 17462 | the serial line to the remote machine. The info is printed on the |
| 17463 | @value{GDBN} standard output stream. The default is off. |
| 17464 | @item show debug remote |
| 17465 | Displays the state of display of remote packets. |
| 17466 | @item set debug serial |
| 17467 | Turns on or off display of @value{GDBN} serial debugging info. The |
| 17468 | default is off. |
| 17469 | @item show debug serial |
| 17470 | Displays the current state of displaying @value{GDBN} serial debugging |
| 17471 | info. |
| 17472 | @item set debug solib-frv |
| 17473 | @cindex FR-V shared-library debugging |
| 17474 | Turns on or off debugging messages for FR-V shared-library code. |
| 17475 | @item show debug solib-frv |
| 17476 | Display the current state of FR-V shared-library code debugging |
| 17477 | messages. |
| 17478 | @item set debug target |
| 17479 | @cindex target debugging info |
| 17480 | Turns on or off display of @value{GDBN} target debugging info. This info |
| 17481 | includes what is going on at the target level of GDB, as it happens. The |
| 17482 | default is 0. Set it to 1 to track events, and to 2 to also track the |
| 17483 | value of large memory transfers. Changes to this flag do not take effect |
| 17484 | until the next time you connect to a target or use the @code{run} command. |
| 17485 | @item show debug target |
| 17486 | Displays the current state of displaying @value{GDBN} target debugging |
| 17487 | info. |
| 17488 | @item set debug timestamp |
| 17489 | @cindex timestampping debugging info |
| 17490 | Turns on or off display of timestamps with @value{GDBN} debugging info. |
| 17491 | When enabled, seconds and microseconds are displayed before each debugging |
| 17492 | message. |
| 17493 | @item show debug timestamp |
| 17494 | Displays the current state of displaying timestamps with @value{GDBN} |
| 17495 | debugging info. |
| 17496 | @item set debugvarobj |
| 17497 | @cindex variable object debugging info |
| 17498 | Turns on or off display of @value{GDBN} variable object debugging |
| 17499 | info. The default is off. |
| 17500 | @item show debugvarobj |
| 17501 | Displays the current state of displaying @value{GDBN} variable object |
| 17502 | debugging info. |
| 17503 | @item set debug xml |
| 17504 | @cindex XML parser debugging |
| 17505 | Turns on or off debugging messages for built-in XML parsers. |
| 17506 | @item show debug xml |
| 17507 | Displays the current state of XML debugging messages. |
| 17508 | @end table |
| 17509 | |
| 17510 | @node Extending GDB |
| 17511 | @chapter Extending @value{GDBN} |
| 17512 | @cindex extending GDB |
| 17513 | |
| 17514 | @value{GDBN} provides two mechanisms for extension. The first is based |
| 17515 | on composition of @value{GDBN} commands, and the second is based on the |
| 17516 | Python scripting language. |
| 17517 | |
| 17518 | @menu |
| 17519 | * Sequences:: Canned Sequences of Commands |
| 17520 | * Python:: Scripting @value{GDBN} using Python |
| 17521 | @end menu |
| 17522 | |
| 17523 | @node Sequences |
| 17524 | @section Canned Sequences of Commands |
| 17525 | |
| 17526 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint |
| 17527 | Command Lists}), @value{GDBN} provides two ways to store sequences of |
| 17528 | commands for execution as a unit: user-defined commands and command |
| 17529 | files. |
| 17530 | |
| 17531 | @menu |
| 17532 | * Define:: How to define your own commands |
| 17533 | * Hooks:: Hooks for user-defined commands |
| 17534 | * Command Files:: How to write scripts of commands to be stored in a file |
| 17535 | * Output:: Commands for controlled output |
| 17536 | @end menu |
| 17537 | |
| 17538 | @node Define |
| 17539 | @subsection User-defined Commands |
| 17540 | |
| 17541 | @cindex user-defined command |
| 17542 | @cindex arguments, to user-defined commands |
| 17543 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to |
| 17544 | which you assign a new name as a command. This is done with the |
| 17545 | @code{define} command. User commands may accept up to 10 arguments |
| 17546 | separated by whitespace. Arguments are accessed within the user command |
| 17547 | via @code{$arg0@dots{}$arg9}. A trivial example: |
| 17548 | |
| 17549 | @smallexample |
| 17550 | define adder |
| 17551 | print $arg0 + $arg1 + $arg2 |
| 17552 | end |
| 17553 | @end smallexample |
| 17554 | |
| 17555 | @noindent |
| 17556 | To execute the command use: |
| 17557 | |
| 17558 | @smallexample |
| 17559 | adder 1 2 3 |
| 17560 | @end smallexample |
| 17561 | |
| 17562 | @noindent |
| 17563 | This defines the command @code{adder}, which prints the sum of |
| 17564 | its three arguments. Note the arguments are text substitutions, so they may |
| 17565 | reference variables, use complex expressions, or even perform inferior |
| 17566 | functions calls. |
| 17567 | |
| 17568 | @cindex argument count in user-defined commands |
| 17569 | @cindex how many arguments (user-defined commands) |
| 17570 | In addition, @code{$argc} may be used to find out how many arguments have |
| 17571 | been passed. This expands to a number in the range 0@dots{}10. |
| 17572 | |
| 17573 | @smallexample |
| 17574 | define adder |
| 17575 | if $argc == 2 |
| 17576 | print $arg0 + $arg1 |
| 17577 | end |
| 17578 | if $argc == 3 |
| 17579 | print $arg0 + $arg1 + $arg2 |
| 17580 | end |
| 17581 | end |
| 17582 | @end smallexample |
| 17583 | |
| 17584 | @table @code |
| 17585 | |
| 17586 | @kindex define |
| 17587 | @item define @var{commandname} |
| 17588 | Define a command named @var{commandname}. If there is already a command |
| 17589 | by that name, you are asked to confirm that you want to redefine it. |
| 17590 | @var{commandname} may be a bare command name consisting of letters, |
| 17591 | numbers, dashes, and underscores. It may also start with any predefined |
| 17592 | prefix command. For example, @samp{define target my-target} creates |
| 17593 | a user-defined @samp{target my-target} command. |
| 17594 | |
| 17595 | The definition of the command is made up of other @value{GDBN} command lines, |
| 17596 | which are given following the @code{define} command. The end of these |
| 17597 | commands is marked by a line containing @code{end}. |
| 17598 | |
| 17599 | @kindex document |
| 17600 | @kindex end@r{ (user-defined commands)} |
| 17601 | @item document @var{commandname} |
| 17602 | Document the user-defined command @var{commandname}, so that it can be |
| 17603 | accessed by @code{help}. The command @var{commandname} must already be |
| 17604 | defined. This command reads lines of documentation just as @code{define} |
| 17605 | reads the lines of the command definition, ending with @code{end}. |
| 17606 | After the @code{document} command is finished, @code{help} on command |
| 17607 | @var{commandname} displays the documentation you have written. |
| 17608 | |
| 17609 | You may use the @code{document} command again to change the |
| 17610 | documentation of a command. Redefining the command with @code{define} |
| 17611 | does not change the documentation. |
| 17612 | |
| 17613 | @kindex dont-repeat |
| 17614 | @cindex don't repeat command |
| 17615 | @item dont-repeat |
| 17616 | Used inside a user-defined command, this tells @value{GDBN} that this |
| 17617 | command should not be repeated when the user hits @key{RET} |
| 17618 | (@pxref{Command Syntax, repeat last command}). |
| 17619 | |
| 17620 | @kindex help user-defined |
| 17621 | @item help user-defined |
| 17622 | List all user-defined commands, with the first line of the documentation |
| 17623 | (if any) for each. |
| 17624 | |
| 17625 | @kindex show user |
| 17626 | @item show user |
| 17627 | @itemx show user @var{commandname} |
| 17628 | Display the @value{GDBN} commands used to define @var{commandname} (but |
| 17629 | not its documentation). If no @var{commandname} is given, display the |
| 17630 | definitions for all user-defined commands. |
| 17631 | |
| 17632 | @cindex infinite recursion in user-defined commands |
| 17633 | @kindex show max-user-call-depth |
| 17634 | @kindex set max-user-call-depth |
| 17635 | @item show max-user-call-depth |
| 17636 | @itemx set max-user-call-depth |
| 17637 | The value of @code{max-user-call-depth} controls how many recursion |
| 17638 | levels are allowed in user-defined commands before @value{GDBN} suspects an |
| 17639 | infinite recursion and aborts the command. |
| 17640 | @end table |
| 17641 | |
| 17642 | In addition to the above commands, user-defined commands frequently |
| 17643 | use control flow commands, described in @ref{Command Files}. |
| 17644 | |
| 17645 | When user-defined commands are executed, the |
| 17646 | commands of the definition are not printed. An error in any command |
| 17647 | stops execution of the user-defined command. |
| 17648 | |
| 17649 | If used interactively, commands that would ask for confirmation proceed |
| 17650 | without asking when used inside a user-defined command. Many @value{GDBN} |
| 17651 | commands that normally print messages to say what they are doing omit the |
| 17652 | messages when used in a user-defined command. |
| 17653 | |
| 17654 | @node Hooks |
| 17655 | @subsection User-defined Command Hooks |
| 17656 | @cindex command hooks |
| 17657 | @cindex hooks, for commands |
| 17658 | @cindex hooks, pre-command |
| 17659 | |
| 17660 | @kindex hook |
| 17661 | You may define @dfn{hooks}, which are a special kind of user-defined |
| 17662 | command. Whenever you run the command @samp{foo}, if the user-defined |
| 17663 | command @samp{hook-foo} exists, it is executed (with no arguments) |
| 17664 | before that command. |
| 17665 | |
| 17666 | @cindex hooks, post-command |
| 17667 | @kindex hookpost |
| 17668 | A hook may also be defined which is run after the command you executed. |
| 17669 | Whenever you run the command @samp{foo}, if the user-defined command |
| 17670 | @samp{hookpost-foo} exists, it is executed (with no arguments) after |
| 17671 | that command. Post-execution hooks may exist simultaneously with |
| 17672 | pre-execution hooks, for the same command. |
| 17673 | |
| 17674 | It is valid for a hook to call the command which it hooks. If this |
| 17675 | occurs, the hook is not re-executed, thereby avoiding infinite recursion. |
| 17676 | |
| 17677 | @c It would be nice if hookpost could be passed a parameter indicating |
| 17678 | @c if the command it hooks executed properly or not. FIXME! |
| 17679 | |
| 17680 | @kindex stop@r{, a pseudo-command} |
| 17681 | In addition, a pseudo-command, @samp{stop} exists. Defining |
| 17682 | (@samp{hook-stop}) makes the associated commands execute every time |
| 17683 | execution stops in your program: before breakpoint commands are run, |
| 17684 | displays are printed, or the stack frame is printed. |
| 17685 | |
| 17686 | For example, to ignore @code{SIGALRM} signals while |
| 17687 | single-stepping, but treat them normally during normal execution, |
| 17688 | you could define: |
| 17689 | |
| 17690 | @smallexample |
| 17691 | define hook-stop |
| 17692 | handle SIGALRM nopass |
| 17693 | end |
| 17694 | |
| 17695 | define hook-run |
| 17696 | handle SIGALRM pass |
| 17697 | end |
| 17698 | |
| 17699 | define hook-continue |
| 17700 | handle SIGALRM pass |
| 17701 | end |
| 17702 | @end smallexample |
| 17703 | |
| 17704 | As a further example, to hook at the beginning and end of the @code{echo} |
| 17705 | command, and to add extra text to the beginning and end of the message, |
| 17706 | you could define: |
| 17707 | |
| 17708 | @smallexample |
| 17709 | define hook-echo |
| 17710 | echo <<<--- |
| 17711 | end |
| 17712 | |
| 17713 | define hookpost-echo |
| 17714 | echo --->>>\n |
| 17715 | end |
| 17716 | |
| 17717 | (@value{GDBP}) echo Hello World |
| 17718 | <<<---Hello World--->>> |
| 17719 | (@value{GDBP}) |
| 17720 | |
| 17721 | @end smallexample |
| 17722 | |
| 17723 | You can define a hook for any single-word command in @value{GDBN}, but |
| 17724 | not for command aliases; you should define a hook for the basic command |
| 17725 | name, e.g.@: @code{backtrace} rather than @code{bt}. |
| 17726 | @c FIXME! So how does Joe User discover whether a command is an alias |
| 17727 | @c or not? |
| 17728 | You can hook a multi-word command by adding @code{hook-} or |
| 17729 | @code{hookpost-} to the last word of the command, e.g.@: |
| 17730 | @samp{define target hook-remote} to add a hook to @samp{target remote}. |
| 17731 | |
| 17732 | If an error occurs during the execution of your hook, execution of |
| 17733 | @value{GDBN} commands stops and @value{GDBN} issues a prompt |
| 17734 | (before the command that you actually typed had a chance to run). |
| 17735 | |
| 17736 | If you try to define a hook which does not match any known command, you |
| 17737 | get a warning from the @code{define} command. |
| 17738 | |
| 17739 | @node Command Files |
| 17740 | @subsection Command Files |
| 17741 | |
| 17742 | @cindex command files |
| 17743 | @cindex scripting commands |
| 17744 | A command file for @value{GDBN} is a text file made of lines that are |
| 17745 | @value{GDBN} commands. Comments (lines starting with @kbd{#}) may |
| 17746 | also be included. An empty line in a command file does nothing; it |
| 17747 | does not mean to repeat the last command, as it would from the |
| 17748 | terminal. |
| 17749 | |
| 17750 | You can request the execution of a command file with the @code{source} |
| 17751 | command: |
| 17752 | |
| 17753 | @table @code |
| 17754 | @kindex source |
| 17755 | @cindex execute commands from a file |
| 17756 | @item source [@code{-v}] @var{filename} |
| 17757 | Execute the command file @var{filename}. |
| 17758 | @end table |
| 17759 | |
| 17760 | The lines in a command file are generally executed sequentially, |
| 17761 | unless the order of execution is changed by one of the |
| 17762 | @emph{flow-control commands} described below. The commands are not |
| 17763 | printed as they are executed. An error in any command terminates |
| 17764 | execution of the command file and control is returned to the console. |
| 17765 | |
| 17766 | @value{GDBN} searches for @var{filename} in the current directory and then |
| 17767 | on the search path (specified with the @samp{directory} command). |
| 17768 | |
| 17769 | If @code{-v}, for verbose mode, is given then @value{GDBN} displays |
| 17770 | each command as it is executed. The option must be given before |
| 17771 | @var{filename}, and is interpreted as part of the filename anywhere else. |
| 17772 | |
| 17773 | Commands that would ask for confirmation if used interactively proceed |
| 17774 | without asking when used in a command file. Many @value{GDBN} commands that |
| 17775 | normally print messages to say what they are doing omit the messages |
| 17776 | when called from command files. |
| 17777 | |
| 17778 | @value{GDBN} also accepts command input from standard input. In this |
| 17779 | mode, normal output goes to standard output and error output goes to |
| 17780 | standard error. Errors in a command file supplied on standard input do |
| 17781 | not terminate execution of the command file---execution continues with |
| 17782 | the next command. |
| 17783 | |
| 17784 | @smallexample |
| 17785 | gdb < cmds > log 2>&1 |
| 17786 | @end smallexample |
| 17787 | |
| 17788 | (The syntax above will vary depending on the shell used.) This example |
| 17789 | will execute commands from the file @file{cmds}. All output and errors |
| 17790 | would be directed to @file{log}. |
| 17791 | |
| 17792 | Since commands stored on command files tend to be more general than |
| 17793 | commands typed interactively, they frequently need to deal with |
| 17794 | complicated situations, such as different or unexpected values of |
| 17795 | variables and symbols, changes in how the program being debugged is |
| 17796 | built, etc. @value{GDBN} provides a set of flow-control commands to |
| 17797 | deal with these complexities. Using these commands, you can write |
| 17798 | complex scripts that loop over data structures, execute commands |
| 17799 | conditionally, etc. |
| 17800 | |
| 17801 | @table @code |
| 17802 | @kindex if |
| 17803 | @kindex else |
| 17804 | @item if |
| 17805 | @itemx else |
| 17806 | This command allows to include in your script conditionally executed |
| 17807 | commands. The @code{if} command takes a single argument, which is an |
| 17808 | expression to evaluate. It is followed by a series of commands that |
| 17809 | are executed only if the expression is true (its value is nonzero). |
| 17810 | There can then optionally be an @code{else} line, followed by a series |
| 17811 | of commands that are only executed if the expression was false. The |
| 17812 | end of the list is marked by a line containing @code{end}. |
| 17813 | |
| 17814 | @kindex while |
| 17815 | @item while |
| 17816 | This command allows to write loops. Its syntax is similar to |
| 17817 | @code{if}: the command takes a single argument, which is an expression |
| 17818 | to evaluate, and must be followed by the commands to execute, one per |
| 17819 | line, terminated by an @code{end}. These commands are called the |
| 17820 | @dfn{body} of the loop. The commands in the body of @code{while} are |
| 17821 | executed repeatedly as long as the expression evaluates to true. |
| 17822 | |
| 17823 | @kindex loop_break |
| 17824 | @item loop_break |
| 17825 | This command exits the @code{while} loop in whose body it is included. |
| 17826 | Execution of the script continues after that @code{while}s @code{end} |
| 17827 | line. |
| 17828 | |
| 17829 | @kindex loop_continue |
| 17830 | @item loop_continue |
| 17831 | This command skips the execution of the rest of the body of commands |
| 17832 | in the @code{while} loop in whose body it is included. Execution |
| 17833 | branches to the beginning of the @code{while} loop, where it evaluates |
| 17834 | the controlling expression. |
| 17835 | |
| 17836 | @kindex end@r{ (if/else/while commands)} |
| 17837 | @item end |
| 17838 | Terminate the block of commands that are the body of @code{if}, |
| 17839 | @code{else}, or @code{while} flow-control commands. |
| 17840 | @end table |
| 17841 | |
| 17842 | |
| 17843 | @node Output |
| 17844 | @subsection Commands for Controlled Output |
| 17845 | |
| 17846 | During the execution of a command file or a user-defined command, normal |
| 17847 | @value{GDBN} output is suppressed; the only output that appears is what is |
| 17848 | explicitly printed by the commands in the definition. This section |
| 17849 | describes three commands useful for generating exactly the output you |
| 17850 | want. |
| 17851 | |
| 17852 | @table @code |
| 17853 | @kindex echo |
| 17854 | @item echo @var{text} |
| 17855 | @c I do not consider backslash-space a standard C escape sequence |
| 17856 | @c because it is not in ANSI. |
| 17857 | Print @var{text}. Nonprinting characters can be included in |
| 17858 | @var{text} using C escape sequences, such as @samp{\n} to print a |
| 17859 | newline. @strong{No newline is printed unless you specify one.} |
| 17860 | In addition to the standard C escape sequences, a backslash followed |
| 17861 | by a space stands for a space. This is useful for displaying a |
| 17862 | string with spaces at the beginning or the end, since leading and |
| 17863 | trailing spaces are otherwise trimmed from all arguments. |
| 17864 | To print @samp{@w{ }and foo =@w{ }}, use the command |
| 17865 | @samp{echo \@w{ }and foo = \@w{ }}. |
| 17866 | |
| 17867 | A backslash at the end of @var{text} can be used, as in C, to continue |
| 17868 | the command onto subsequent lines. For example, |
| 17869 | |
| 17870 | @smallexample |
| 17871 | echo This is some text\n\ |
| 17872 | which is continued\n\ |
| 17873 | onto several lines.\n |
| 17874 | @end smallexample |
| 17875 | |
| 17876 | produces the same output as |
| 17877 | |
| 17878 | @smallexample |
| 17879 | echo This is some text\n |
| 17880 | echo which is continued\n |
| 17881 | echo onto several lines.\n |
| 17882 | @end smallexample |
| 17883 | |
| 17884 | @kindex output |
| 17885 | @item output @var{expression} |
| 17886 | Print the value of @var{expression} and nothing but that value: no |
| 17887 | newlines, no @samp{$@var{nn} = }. The value is not entered in the |
| 17888 | value history either. @xref{Expressions, ,Expressions}, for more information |
| 17889 | on expressions. |
| 17890 | |
| 17891 | @item output/@var{fmt} @var{expression} |
| 17892 | Print the value of @var{expression} in format @var{fmt}. You can use |
| 17893 | the same formats as for @code{print}. @xref{Output Formats,,Output |
| 17894 | Formats}, for more information. |
| 17895 | |
| 17896 | @kindex printf |
| 17897 | @item printf @var{template}, @var{expressions}@dots{} |
| 17898 | Print the values of one or more @var{expressions} under the control of |
| 17899 | the string @var{template}. To print several values, make |
| 17900 | @var{expressions} be a comma-separated list of individual expressions, |
| 17901 | which may be either numbers or pointers. Their values are printed as |
| 17902 | specified by @var{template}, exactly as a C program would do by |
| 17903 | executing the code below: |
| 17904 | |
| 17905 | @smallexample |
| 17906 | printf (@var{template}, @var{expressions}@dots{}); |
| 17907 | @end smallexample |
| 17908 | |
| 17909 | As in @code{C} @code{printf}, ordinary characters in @var{template} |
| 17910 | are printed verbatim, while @dfn{conversion specification} introduced |
| 17911 | by the @samp{%} character cause subsequent @var{expressions} to be |
| 17912 | evaluated, their values converted and formatted according to type and |
| 17913 | style information encoded in the conversion specifications, and then |
| 17914 | printed. |
| 17915 | |
| 17916 | For example, you can print two values in hex like this: |
| 17917 | |
| 17918 | @smallexample |
| 17919 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo |
| 17920 | @end smallexample |
| 17921 | |
| 17922 | @code{printf} supports all the standard @code{C} conversion |
| 17923 | specifications, including the flags and modifiers between the @samp{%} |
| 17924 | character and the conversion letter, with the following exceptions: |
| 17925 | |
| 17926 | @itemize @bullet |
| 17927 | @item |
| 17928 | The argument-ordering modifiers, such as @samp{2$}, are not supported. |
| 17929 | |
| 17930 | @item |
| 17931 | The modifier @samp{*} is not supported for specifying precision or |
| 17932 | width. |
| 17933 | |
| 17934 | @item |
| 17935 | The @samp{'} flag (for separation of digits into groups according to |
| 17936 | @code{LC_NUMERIC'}) is not supported. |
| 17937 | |
| 17938 | @item |
| 17939 | The type modifiers @samp{hh}, @samp{j}, @samp{t}, and @samp{z} are not |
| 17940 | supported. |
| 17941 | |
| 17942 | @item |
| 17943 | The conversion letter @samp{n} (as in @samp{%n}) is not supported. |
| 17944 | |
| 17945 | @item |
| 17946 | The conversion letters @samp{a} and @samp{A} are not supported. |
| 17947 | @end itemize |
| 17948 | |
| 17949 | @noindent |
| 17950 | Note that the @samp{ll} type modifier is supported only if the |
| 17951 | underlying @code{C} implementation used to build @value{GDBN} supports |
| 17952 | the @code{long long int} type, and the @samp{L} type modifier is |
| 17953 | supported only if @code{long double} type is available. |
| 17954 | |
| 17955 | As in @code{C}, @code{printf} supports simple backslash-escape |
| 17956 | sequences, such as @code{\n}, @samp{\t}, @samp{\\}, @samp{\"}, |
| 17957 | @samp{\a}, and @samp{\f}, that consist of backslash followed by a |
| 17958 | single character. Octal and hexadecimal escape sequences are not |
| 17959 | supported. |
| 17960 | |
| 17961 | Additionally, @code{printf} supports conversion specifications for DFP |
| 17962 | (@dfn{Decimal Floating Point}) types using the following length modifiers |
| 17963 | together with a floating point specifier. |
| 17964 | letters: |
| 17965 | |
| 17966 | @itemize @bullet |
| 17967 | @item |
| 17968 | @samp{H} for printing @code{Decimal32} types. |
| 17969 | |
| 17970 | @item |
| 17971 | @samp{D} for printing @code{Decimal64} types. |
| 17972 | |
| 17973 | @item |
| 17974 | @samp{DD} for printing @code{Decimal128} types. |
| 17975 | @end itemize |
| 17976 | |
| 17977 | If the underlying @code{C} implementation used to build @value{GDBN} has |
| 17978 | support for the three length modifiers for DFP types, other modifiers |
| 17979 | such as width and precision will also be available for @value{GDBN} to use. |
| 17980 | |
| 17981 | In case there is no such @code{C} support, no additional modifiers will be |
| 17982 | available and the value will be printed in the standard way. |
| 17983 | |
| 17984 | Here's an example of printing DFP types using the above conversion letters: |
| 17985 | @smallexample |
| 17986 | printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl |
| 17987 | @end smallexample |
| 17988 | |
| 17989 | @end table |
| 17990 | |
| 17991 | @node Python |
| 17992 | @section Scripting @value{GDBN} using Python |
| 17993 | @cindex python scripting |
| 17994 | @cindex scripting with python |
| 17995 | |
| 17996 | You can script @value{GDBN} using the @uref{http://www.python.org/, |
| 17997 | Python programming language}. This feature is available only if |
| 17998 | @value{GDBN} was configured using @option{--with-python}. |
| 17999 | |
| 18000 | @menu |
| 18001 | * Python Commands:: Accessing Python from @value{GDBN}. |
| 18002 | * Python API:: Accessing @value{GDBN} from Python. |
| 18003 | @end menu |
| 18004 | |
| 18005 | @node Python Commands |
| 18006 | @subsection Python Commands |
| 18007 | @cindex python commands |
| 18008 | @cindex commands to access python |
| 18009 | |
| 18010 | @value{GDBN} provides one command for accessing the Python interpreter, |
| 18011 | and one related setting: |
| 18012 | |
| 18013 | @table @code |
| 18014 | @kindex python |
| 18015 | @item python @r{[}@var{code}@r{]} |
| 18016 | The @code{python} command can be used to evaluate Python code. |
| 18017 | |
| 18018 | If given an argument, the @code{python} command will evaluate the |
| 18019 | argument as a Python command. For example: |
| 18020 | |
| 18021 | @smallexample |
| 18022 | (@value{GDBP}) python print 23 |
| 18023 | 23 |
| 18024 | @end smallexample |
| 18025 | |
| 18026 | If you do not provide an argument to @code{python}, it will act as a |
| 18027 | multi-line command, like @code{define}. In this case, the Python |
| 18028 | script is made up of subsequent command lines, given after the |
| 18029 | @code{python} command. This command list is terminated using a line |
| 18030 | containing @code{end}. For example: |
| 18031 | |
| 18032 | @smallexample |
| 18033 | (@value{GDBP}) python |
| 18034 | Type python script |
| 18035 | End with a line saying just "end". |
| 18036 | >print 23 |
| 18037 | >end |
| 18038 | 23 |
| 18039 | @end smallexample |
| 18040 | |
| 18041 | @kindex maint set python print-stack |
| 18042 | @item maint set python print-stack |
| 18043 | By default, @value{GDBN} will print a stack trace when an error occurs |
| 18044 | in a Python script. This can be controlled using @code{maint set |
| 18045 | python print-stack}: if @code{on}, the default, then Python stack |
| 18046 | printing is enabled; if @code{off}, then Python stack printing is |
| 18047 | disabled. |
| 18048 | @end table |
| 18049 | |
| 18050 | @node Python API |
| 18051 | @subsection Python API |
| 18052 | @cindex python api |
| 18053 | @cindex programming in python |
| 18054 | |
| 18055 | @cindex python stdout |
| 18056 | @cindex python pagination |
| 18057 | At startup, @value{GDBN} overrides Python's @code{sys.stdout} and |
| 18058 | @code{sys.stderr} to print using @value{GDBN}'s output-paging streams. |
| 18059 | A Python program which outputs to one of these streams may have its |
| 18060 | output interrupted by the user (@pxref{Screen Size}). In this |
| 18061 | situation, a Python @code{KeyboardInterrupt} exception is thrown. |
| 18062 | |
| 18063 | @menu |
| 18064 | * Basic Python:: Basic Python Functions. |
| 18065 | * Exception Handling:: |
| 18066 | * Values From Inferior:: |
| 18067 | * Commands In Python:: Implementing new commands in Python. |
| 18068 | @end menu |
| 18069 | |
| 18070 | @node Basic Python |
| 18071 | @subsubsection Basic Python |
| 18072 | |
| 18073 | @cindex python functions |
| 18074 | @cindex python module |
| 18075 | @cindex gdb module |
| 18076 | @value{GDBN} introduces a new Python module, named @code{gdb}. All |
| 18077 | methods and classes added by @value{GDBN} are placed in this module. |
| 18078 | @value{GDBN} automatically @code{import}s the @code{gdb} module for |
| 18079 | use in all scripts evaluated by the @code{python} command. |
| 18080 | |
| 18081 | @findex gdb.execute |
| 18082 | @defun execute command [from_tty] |
| 18083 | Evaluate @var{command}, a string, as a @value{GDBN} CLI command. |
| 18084 | If a GDB exception happens while @var{command} runs, it is |
| 18085 | translated as described in @ref{Exception Handling,,Exception Handling}. |
| 18086 | If no exceptions occur, this function returns @code{None}. |
| 18087 | |
| 18088 | @var{from_tty} specifies whether @value{GDBN} ought to consider this |
| 18089 | command as having originated from the user invoking it interactively. |
| 18090 | It must be a boolean value. If omitted, it defaults to @code{False}. |
| 18091 | @end defun |
| 18092 | |
| 18093 | @findex gdb.get_parameter |
| 18094 | @defun get_parameter parameter |
| 18095 | Return the value of a @value{GDBN} parameter. @var{parameter} is a |
| 18096 | string naming the parameter to look up; @var{parameter} may contain |
| 18097 | spaces if the parameter has a multi-part name. For example, |
| 18098 | @samp{print object} is a valid parameter name. |
| 18099 | |
| 18100 | If the named parameter does not exist, this function throws a |
| 18101 | @code{RuntimeError}. Otherwise, the parameter's value is converted to |
| 18102 | a Python value of the appropriate type, and returned. |
| 18103 | @end defun |
| 18104 | |
| 18105 | @findex gdb.history |
| 18106 | @defun history number |
| 18107 | Return a value from @value{GDBN}'s value history (@pxref{Value |
| 18108 | History}). @var{number} indicates which history element to return. |
| 18109 | If @var{number} is negative, then @value{GDBN} will take its absolute value |
| 18110 | and count backward from the last element (i.e., the most recent element) to |
| 18111 | find the value to return. If @var{number} is zero, then @value{GDBN} will |
| 18112 | return the most recent element. If the element specified by @value{number} |
| 18113 | doesn't exist in the value history, a @code{RuntimeError} exception will be |
| 18114 | raised. |
| 18115 | |
| 18116 | If no exception is raised, the return value is always an instance of |
| 18117 | @code{gdb.Value} (@pxref{Values From Inferior}). |
| 18118 | @end defun |
| 18119 | |
| 18120 | @findex gdb.write |
| 18121 | @defun write string |
| 18122 | Print a string to @value{GDBN}'s paginated standard output stream. |
| 18123 | Writing to @code{sys.stdout} or @code{sys.stderr} will automatically |
| 18124 | call this function. |
| 18125 | @end defun |
| 18126 | |
| 18127 | @findex gdb.flush |
| 18128 | @defun flush |
| 18129 | Flush @value{GDBN}'s paginated standard output stream. Flushing |
| 18130 | @code{sys.stdout} or @code{sys.stderr} will automatically call this |
| 18131 | function. |
| 18132 | @end defun |
| 18133 | |
| 18134 | @node Exception Handling |
| 18135 | @subsubsection Exception Handling |
| 18136 | @cindex python exceptions |
| 18137 | @cindex exceptions, python |
| 18138 | |
| 18139 | When executing the @code{python} command, Python exceptions |
| 18140 | uncaught within the Python code are translated to calls to |
| 18141 | @value{GDBN} error-reporting mechanism. If the command that called |
| 18142 | @code{python} does not handle the error, @value{GDBN} will |
| 18143 | terminate it and print an error message containing the Python |
| 18144 | exception name, the associated value, and the Python call stack |
| 18145 | backtrace at the point where the exception was raised. Example: |
| 18146 | |
| 18147 | @smallexample |
| 18148 | (@value{GDBP}) python print foo |
| 18149 | Traceback (most recent call last): |
| 18150 | File "<string>", line 1, in <module> |
| 18151 | NameError: name 'foo' is not defined |
| 18152 | @end smallexample |
| 18153 | |
| 18154 | @value{GDBN} errors that happen in @value{GDBN} commands invoked by Python |
| 18155 | code are converted to Python @code{RuntimeError} exceptions. User |
| 18156 | interrupt (via @kbd{C-c} or by typing @kbd{q} at a pagination |
| 18157 | prompt) is translated to a Python @code{KeyboardInterrupt} |
| 18158 | exception. If you catch these exceptions in your Python code, your |
| 18159 | exception handler will see @code{RuntimeError} or |
| 18160 | @code{KeyboardInterrupt} as the exception type, the @value{GDBN} error |
| 18161 | message as its value, and the Python call stack backtrace at the |
| 18162 | Python statement closest to where the @value{GDBN} error occured as the |
| 18163 | traceback. |
| 18164 | |
| 18165 | @node Values From Inferior |
| 18166 | @subsubsection Values From Inferior |
| 18167 | @cindex values from inferior, with Python |
| 18168 | @cindex python, working with values from inferior |
| 18169 | |
| 18170 | @cindex @code{gdb.Value} |
| 18171 | @value{GDBN} provides values it obtains from the inferior program in |
| 18172 | an object of type @code{gdb.Value}. @value{GDBN} uses this object |
| 18173 | for its internal bookkeeping of the inferior's values, and for |
| 18174 | fetching values when necessary. |
| 18175 | |
| 18176 | Inferior values that are simple scalars can be used directly in |
| 18177 | Python expressions that are valid for the value's data type. Here's |
| 18178 | an example for an integer or floating-point value @code{some_val}: |
| 18179 | |
| 18180 | @smallexample |
| 18181 | bar = some_val + 2 |
| 18182 | @end smallexample |
| 18183 | |
| 18184 | @noindent |
| 18185 | As result of this, @code{bar} will also be a @code{gdb.Value} object |
| 18186 | whose values are of the same type as those of @code{some_val}. |
| 18187 | |
| 18188 | Inferior values that are structures or instances of some class can |
| 18189 | be accessed using the Python @dfn{dictionary syntax}. For example, if |
| 18190 | @code{some_val} is a @code{gdb.Value} instance holding a structure, you |
| 18191 | can access its @code{foo} element with: |
| 18192 | |
| 18193 | @smallexample |
| 18194 | bar = some_val['foo'] |
| 18195 | @end smallexample |
| 18196 | |
| 18197 | Again, @code{bar} will also be a @code{gdb.Value} object. |
| 18198 | |
| 18199 | For pointer data types, @code{gdb.Value} provides a method for |
| 18200 | dereferencing the pointer to obtain the object it points to. |
| 18201 | |
| 18202 | @defmethod Value dereference |
| 18203 | This method returns a new @code{gdb.Value} object whose contents is |
| 18204 | the object pointed to by the pointer. For example, if @code{foo} is |
| 18205 | a C pointer to an @code{int}, declared in your C program as |
| 18206 | |
| 18207 | @smallexample |
| 18208 | int *foo; |
| 18209 | @end smallexample |
| 18210 | |
| 18211 | @noindent |
| 18212 | then you can use the corresponding @code{gdb.Value} to access what |
| 18213 | @code{foo} points to like this: |
| 18214 | |
| 18215 | @smallexample |
| 18216 | bar = foo.dereference () |
| 18217 | @end smallexample |
| 18218 | |
| 18219 | The result @code{bar} will be a @code{gdb.Value} object holding the |
| 18220 | value pointed to by @code{foo}. |
| 18221 | @end defmethod |
| 18222 | |
| 18223 | @defmethod Value string @r{[}encoding @r{[}errors@r{]}@r{]} |
| 18224 | If this @code{gdb.Value} represents a string, then this method |
| 18225 | converts the contents to a Python string. Otherwise, this method will |
| 18226 | throw an exception. |
| 18227 | |
| 18228 | Strings are recognized in a language-specific way; whether a given |
| 18229 | @code{gdb.Value} represents a string is determined by the current |
| 18230 | language. |
| 18231 | |
| 18232 | For C-like languages, a value is a string if it is a pointer to or an |
| 18233 | array of characters or ints. The string is assumed to be terminated |
| 18234 | by a zero of the appropriate width. |
| 18235 | |
| 18236 | If the optional @var{encoding} argument is given, it must be a string |
| 18237 | naming the encoding of the string in the @code{gdb.Value}, such as |
| 18238 | @code{"ascii"}, @code{"iso-8859-6"} or @code{"utf-8"}. It accepts |
| 18239 | the same encodings as the corresponding argument to Python's |
| 18240 | @code{string.decode} method, and the Python codec machinery will be used |
| 18241 | to convert the string. If @var{encoding} is not given, or if |
| 18242 | @var{encoding} is the empty string, then either the @code{target-charset} |
| 18243 | (@pxref{Character Sets}) will be used, or a language-specific encoding |
| 18244 | will be used, if the current language is able to supply one. |
| 18245 | |
| 18246 | The optional @var{errors} argument is the same as the corresponding |
| 18247 | argument to Python's @code{string.decode} method. |
| 18248 | @end defmethod |
| 18249 | |
| 18250 | @node Commands In Python |
| 18251 | @subsubsection Commands In Python |
| 18252 | |
| 18253 | @cindex commands in python |
| 18254 | @cindex python commands |
| 18255 | @tindex Command |
| 18256 | @tindex gdb.Command |
| 18257 | You can implement new @value{GDBN} CLI commands in Python. A CLI |
| 18258 | command is implemented using an instance of the @code{gdb.Command} |
| 18259 | class, most commonly using a subclass. |
| 18260 | |
| 18261 | @defmethod Command __init__ name @var{command-class} @r{[}@var{completer-class} @var{prefix}@r{]} |
| 18262 | The object initializer for @code{Command} registers the new command |
| 18263 | with @value{GDBN}. This initializer is normally invoked from the |
| 18264 | subclass' own @code{__init__} method. |
| 18265 | |
| 18266 | @var{name} is the name of the command. If @var{name} consists of |
| 18267 | multiple words, then the initial words are looked for as prefix |
| 18268 | commands. In this case, if one of the prefix commands does not exist, |
| 18269 | an exception is raised. |
| 18270 | |
| 18271 | There is no support for multi-line commands. |
| 18272 | |
| 18273 | @var{command-class} should be one of the @samp{COMMAND_} constants |
| 18274 | defined below. This argument tells @value{GDBN} how to categorize the |
| 18275 | new command in the help system. |
| 18276 | |
| 18277 | @var{completer-class} is an optional argument. If given, it should be |
| 18278 | one of the @samp{COMPLETE_} constants defined below. This argument |
| 18279 | tells @value{GDBN} how to perform completion for this command. If not |
| 18280 | given, @value{GDBN} will attempt to complete using the object's |
| 18281 | @code{complete} method (see below); if no such method is found, an |
| 18282 | error will occur when completion is attempted. |
| 18283 | |
| 18284 | @var{prefix} is an optional argument. If @code{True}, then the new |
| 18285 | command is a prefix command; sub-commands of this command may be |
| 18286 | registered. |
| 18287 | |
| 18288 | The help text for the new command is taken from the Python |
| 18289 | documentation string for the command's class, if there is one. If no |
| 18290 | documentation string is provided, the default value ``This command is |
| 18291 | not documented.'' is used. |
| 18292 | @end defmethod |
| 18293 | |
| 18294 | @defmethod Command dont_repeat |
| 18295 | By default, a @value{GDBN} command is repeated when the user enters a |
| 18296 | blank line at the command prompt. A command can suppress this |
| 18297 | behavior by invoking the @code{dont_repeat} method. This is similar |
| 18298 | to the user command @code{dont-repeat}, see @ref{Define, dont-repeat}. |
| 18299 | @end defmethod |
| 18300 | |
| 18301 | @defmethod Command invoke argument from_tty |
| 18302 | This method is called by @value{GDBN} when this command is invoked. |
| 18303 | |
| 18304 | @var{argument} is a string. It is the argument to the command, after |
| 18305 | leading and trailing whitespace has been stripped. |
| 18306 | |
| 18307 | @var{from_tty} is a boolean argument. When true, this means that the |
| 18308 | command was entered by the user at the terminal; when false it means |
| 18309 | that the command came from elsewhere. |
| 18310 | |
| 18311 | If this method throws an exception, it is turned into a @value{GDBN} |
| 18312 | @code{error} call. Otherwise, the return value is ignored. |
| 18313 | @end defmethod |
| 18314 | |
| 18315 | @defmethod Command complete text word |
| 18316 | This method is called by @value{GDBN} when the user attempts |
| 18317 | completion on this command. All forms of completion are handled by |
| 18318 | this method, that is, the @key{TAB} and @key{M-?} key bindings, and |
| 18319 | the @code{complete} command. |
| 18320 | |
| 18321 | The arguments @var{text} and @var{word} are both strings. @var{text} |
| 18322 | holds the complete command line up to the cursor's location. |
| 18323 | @var{word} holds the last word of the command line; this is computed |
| 18324 | using a word-breaking heuristic. |
| 18325 | |
| 18326 | The @code{complete} method can return several values: |
| 18327 | @itemize @bullet |
| 18328 | @item |
| 18329 | If the return value is a sequence, the contents of the sequence are |
| 18330 | used as the completions. It is up to @code{complete} to ensure that the |
| 18331 | contents actually do complete the word. A zero-length sequence is |
| 18332 | allowed, it means that there were no completions available. Only |
| 18333 | string elements of the sequence are used; other elements in the |
| 18334 | sequence are ignored. |
| 18335 | |
| 18336 | @item |
| 18337 | If the return value is one of the @samp{COMPLETE_} constants defined |
| 18338 | below, then the corresponding @value{GDBN}-internal completion |
| 18339 | function is invoked, and its result is used. |
| 18340 | |
| 18341 | @item |
| 18342 | All other results are treated as though there were no available |
| 18343 | completions. |
| 18344 | @end itemize |
| 18345 | @end defmethod |
| 18346 | |
| 18347 | |
| 18348 | When a new command is registered, it must be declared as a member of |
| 18349 | some general class of commands. This is used to classify top-level |
| 18350 | commands in the on-line help system; note that prefix commands are not |
| 18351 | listed under their own category but rather that of their top-level |
| 18352 | command. The available classifications are represented by constants |
| 18353 | defined in the @code{gdb} module: |
| 18354 | |
| 18355 | @table @code |
| 18356 | @findex COMMAND_NONE |
| 18357 | @findex gdb.COMMAND_NONE |
| 18358 | @item COMMAND_NONE |
| 18359 | The command does not belong to any particular class. A command in |
| 18360 | this category will not be displayed in any of the help categories. |
| 18361 | |
| 18362 | @findex COMMAND_RUNNING |
| 18363 | @findex gdb.COMMAND_RUNNING |
| 18364 | @item COMMAND_RUN |
| 18365 | The command is related to running the inferior. For example, |
| 18366 | @code{start}, @code{step}, and @code{continue} are in this category. |
| 18367 | Type @code{help running} at the @value{GDBN} prompt to see a list of |
| 18368 | commands in this category. |
| 18369 | |
| 18370 | @findex COMMAND_DATA |
| 18371 | @findex gdb.COMMAND_DATA |
| 18372 | @item COMMAND_VARS |
| 18373 | The command is related to data or variables. For example, |
| 18374 | @code{call}, @code{find}, and @code{print} are in this category. Type |
| 18375 | @code{help data} at the @value{GDBN} prompt to see a list of commands |
| 18376 | in this category. |
| 18377 | |
| 18378 | @findex COMMAND_STACK |
| 18379 | @findex gdb.COMMAND_STACK |
| 18380 | @item COMMAND_STACK |
| 18381 | The command has to do with manipulation of the stack. For example, |
| 18382 | @code{backtrace}, @code{frame}, and @code{return} are in this |
| 18383 | category. Type @code{help stack} at the @value{GDBN} prompt to see a |
| 18384 | list of commands in this category. |
| 18385 | |
| 18386 | @findex COMMAND_FILES |
| 18387 | @findex gdb.COMMAND_FILES |
| 18388 | @item COMMAND_FILES |
| 18389 | This class is used for file-related commands. For example, |
| 18390 | @code{file}, @code{list} and @code{section} are in this category. |
| 18391 | Type @code{help files} at the @value{GDBN} prompt to see a list of |
| 18392 | commands in this category. |
| 18393 | |
| 18394 | @findex COMMAND_SUPPORT |
| 18395 | @findex gdb.COMMAND_SUPPORT |
| 18396 | @item COMMAND_SUPPORT |
| 18397 | This should be used for ``support facilities'', generally meaning |
| 18398 | things that are useful to the user when interacting with @value{GDBN}, |
| 18399 | but not related to the state of the inferior. For example, |
| 18400 | @code{help}, @code{make}, and @code{shell} are in this category. Type |
| 18401 | @code{help support} at the @value{GDBN} prompt to see a list of |
| 18402 | commands in this category. |
| 18403 | |
| 18404 | @findex COMMAND_STATUS |
| 18405 | @findex gdb.COMMAND_STATUS |
| 18406 | @item COMMAND_INFO |
| 18407 | The command is an @samp{info}-related command, that is, related to the |
| 18408 | state of @value{GDBN} itself. For example, @code{info}, @code{macro}, |
| 18409 | and @code{show} are in this category. Type @code{help status} at the |
| 18410 | @value{GDBN} prompt to see a list of commands in this category. |
| 18411 | |
| 18412 | @findex COMMAND_BREAKPOINTS |
| 18413 | @findex gdb.COMMAND_BREAKPOINTS |
| 18414 | @item COMMAND_BREAKPOINT |
| 18415 | The command has to do with breakpoints. For example, @code{break}, |
| 18416 | @code{clear}, and @code{delete} are in this category. Type @code{help |
| 18417 | breakpoints} at the @value{GDBN} prompt to see a list of commands in |
| 18418 | this category. |
| 18419 | |
| 18420 | @findex COMMAND_TRACEPOINTS |
| 18421 | @findex gdb.COMMAND_TRACEPOINTS |
| 18422 | @item COMMAND_TRACE |
| 18423 | The command has to do with tracepoints. For example, @code{trace}, |
| 18424 | @code{actions}, and @code{tfind} are in this category. Type |
| 18425 | @code{help tracepoints} at the @value{GDBN} prompt to see a list of |
| 18426 | commands in this category. |
| 18427 | |
| 18428 | @findex COMMAND_OBSCURE |
| 18429 | @findex gdb.COMMAND_OBSCURE |
| 18430 | @item COMMAND_OBSCURE |
| 18431 | The command is only used in unusual circumstances, or is not of |
| 18432 | general interest to users. For example, @code{checkpoint}, |
| 18433 | @code{fork}, and @code{stop} are in this category. Type @code{help |
| 18434 | obscure} at the @value{GDBN} prompt to see a list of commands in this |
| 18435 | category. |
| 18436 | |
| 18437 | @findex COMMAND_MAINTENANCE |
| 18438 | @findex gdb.COMMAND_MAINTENANCE |
| 18439 | @item COMMAND_MAINTENANCE |
| 18440 | The command is only useful to @value{GDBN} maintainers. The |
| 18441 | @code{maintenance} and @code{flushregs} commands are in this category. |
| 18442 | Type @code{help internals} at the @value{GDBN} prompt to see a list of |
| 18443 | commands in this category. |
| 18444 | @end table |
| 18445 | |
| 18446 | |
| 18447 | A new command can use a predefined completion function, either by |
| 18448 | specifying it via an argument at initialization, or by returning it |
| 18449 | from the @code{complete} method. These predefined completion |
| 18450 | constants are all defined in the @code{gdb} module: |
| 18451 | |
| 18452 | @table @code |
| 18453 | @findex COMPLETE_NONE |
| 18454 | @findex gdb.COMPLETE_NONE |
| 18455 | @item COMPLETE_NONE |
| 18456 | This constant means that no completion should be done. |
| 18457 | |
| 18458 | @findex COMPLETE_FILENAME |
| 18459 | @findex gdb.COMPLETE_FILENAME |
| 18460 | @item COMPLETE_FILENAME |
| 18461 | This constant means that filename completion should be performed. |
| 18462 | |
| 18463 | @findex COMPLETE_LOCATION |
| 18464 | @findex gdb.COMPLETE_LOCATION |
| 18465 | @item COMPLETE_LOCATION |
| 18466 | This constant means that location completion should be done. |
| 18467 | @xref{Specify Location}. |
| 18468 | |
| 18469 | @findex COMPLETE_COMMAND |
| 18470 | @findex gdb.COMPLETE_COMMAND |
| 18471 | @item COMPLETE_COMMAND |
| 18472 | This constant means that completion should examine @value{GDBN} |
| 18473 | command names. |
| 18474 | |
| 18475 | @findex COMPLETE_SYMBOL |
| 18476 | @findex gdb.COMPLETE_SYMBOL |
| 18477 | @item COMPLETE_SYMBOL |
| 18478 | This constant means that completion should be done using symbol names |
| 18479 | as the source. |
| 18480 | @end table |
| 18481 | |
| 18482 | The following code snippet shows how a trivial CLI command can be |
| 18483 | implemented in Python: |
| 18484 | |
| 18485 | @smallexample |
| 18486 | class HelloWorld (gdb.Command): |
| 18487 | """Greet the whole world.""" |
| 18488 | |
| 18489 | def __init__ (self): |
| 18490 | super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_OBSCURE) |
| 18491 | |
| 18492 | def invoke (self, arg, from_tty): |
| 18493 | print "Hello, World!" |
| 18494 | |
| 18495 | HelloWorld () |
| 18496 | @end smallexample |
| 18497 | |
| 18498 | The last line instantiates the class, and is necessary to trigger the |
| 18499 | registration of the command with @value{GDBN}. Depending on how the |
| 18500 | Python code is read into @value{GDBN}, you may need to import the |
| 18501 | @code{gdb} module explicitly. |
| 18502 | |
| 18503 | @node Interpreters |
| 18504 | @chapter Command Interpreters |
| 18505 | @cindex command interpreters |
| 18506 | |
| 18507 | @value{GDBN} supports multiple command interpreters, and some command |
| 18508 | infrastructure to allow users or user interface writers to switch |
| 18509 | between interpreters or run commands in other interpreters. |
| 18510 | |
| 18511 | @value{GDBN} currently supports two command interpreters, the console |
| 18512 | interpreter (sometimes called the command-line interpreter or @sc{cli}) |
| 18513 | and the machine interface interpreter (or @sc{gdb/mi}). This manual |
| 18514 | describes both of these interfaces in great detail. |
| 18515 | |
| 18516 | By default, @value{GDBN} will start with the console interpreter. |
| 18517 | However, the user may choose to start @value{GDBN} with another |
| 18518 | interpreter by specifying the @option{-i} or @option{--interpreter} |
| 18519 | startup options. Defined interpreters include: |
| 18520 | |
| 18521 | @table @code |
| 18522 | @item console |
| 18523 | @cindex console interpreter |
| 18524 | The traditional console or command-line interpreter. This is the most often |
| 18525 | used interpreter with @value{GDBN}. With no interpreter specified at runtime, |
| 18526 | @value{GDBN} will use this interpreter. |
| 18527 | |
| 18528 | @item mi |
| 18529 | @cindex mi interpreter |
| 18530 | The newest @sc{gdb/mi} interface (currently @code{mi2}). Used primarily |
| 18531 | by programs wishing to use @value{GDBN} as a backend for a debugger GUI |
| 18532 | or an IDE. For more information, see @ref{GDB/MI, ,The @sc{gdb/mi} |
| 18533 | Interface}. |
| 18534 | |
| 18535 | @item mi2 |
| 18536 | @cindex mi2 interpreter |
| 18537 | The current @sc{gdb/mi} interface. |
| 18538 | |
| 18539 | @item mi1 |
| 18540 | @cindex mi1 interpreter |
| 18541 | The @sc{gdb/mi} interface included in @value{GDBN} 5.1, 5.2, and 5.3. |
| 18542 | |
| 18543 | @end table |
| 18544 | |
| 18545 | @cindex invoke another interpreter |
| 18546 | The interpreter being used by @value{GDBN} may not be dynamically |
| 18547 | switched at runtime. Although possible, this could lead to a very |
| 18548 | precarious situation. Consider an IDE using @sc{gdb/mi}. If a user |
| 18549 | enters the command "interpreter-set console" in a console view, |
| 18550 | @value{GDBN} would switch to using the console interpreter, rendering |
| 18551 | the IDE inoperable! |
| 18552 | |
| 18553 | @kindex interpreter-exec |
| 18554 | Although you may only choose a single interpreter at startup, you may execute |
| 18555 | commands in any interpreter from the current interpreter using the appropriate |
| 18556 | command. If you are running the console interpreter, simply use the |
| 18557 | @code{interpreter-exec} command: |
| 18558 | |
| 18559 | @smallexample |
| 18560 | interpreter-exec mi "-data-list-register-names" |
| 18561 | @end smallexample |
| 18562 | |
| 18563 | @sc{gdb/mi} has a similar command, although it is only available in versions of |
| 18564 | @value{GDBN} which support @sc{gdb/mi} version 2 (or greater). |
| 18565 | |
| 18566 | @node TUI |
| 18567 | @chapter @value{GDBN} Text User Interface |
| 18568 | @cindex TUI |
| 18569 | @cindex Text User Interface |
| 18570 | |
| 18571 | @menu |
| 18572 | * TUI Overview:: TUI overview |
| 18573 | * TUI Keys:: TUI key bindings |
| 18574 | * TUI Single Key Mode:: TUI single key mode |
| 18575 | * TUI Commands:: TUI-specific commands |
| 18576 | * TUI Configuration:: TUI configuration variables |
| 18577 | @end menu |
| 18578 | |
| 18579 | The @value{GDBN} Text User Interface (TUI) is a terminal |
| 18580 | interface which uses the @code{curses} library to show the source |
| 18581 | file, the assembly output, the program registers and @value{GDBN} |
| 18582 | commands in separate text windows. The TUI mode is supported only |
| 18583 | on platforms where a suitable version of the @code{curses} library |
| 18584 | is available. |
| 18585 | |
| 18586 | @pindex @value{GDBTUI} |
| 18587 | The TUI mode is enabled by default when you invoke @value{GDBN} as |
| 18588 | either @samp{@value{GDBTUI}} or @samp{@value{GDBP} -tui}. |
| 18589 | You can also switch in and out of TUI mode while @value{GDBN} runs by |
| 18590 | using various TUI commands and key bindings, such as @kbd{C-x C-a}. |
| 18591 | @xref{TUI Keys, ,TUI Key Bindings}. |
| 18592 | |
| 18593 | @node TUI Overview |
| 18594 | @section TUI Overview |
| 18595 | |
| 18596 | In TUI mode, @value{GDBN} can display several text windows: |
| 18597 | |
| 18598 | @table @emph |
| 18599 | @item command |
| 18600 | This window is the @value{GDBN} command window with the @value{GDBN} |
| 18601 | prompt and the @value{GDBN} output. The @value{GDBN} input is still |
| 18602 | managed using readline. |
| 18603 | |
| 18604 | @item source |
| 18605 | The source window shows the source file of the program. The current |
| 18606 | line and active breakpoints are displayed in this window. |
| 18607 | |
| 18608 | @item assembly |
| 18609 | The assembly window shows the disassembly output of the program. |
| 18610 | |
| 18611 | @item register |
| 18612 | This window shows the processor registers. Registers are highlighted |
| 18613 | when their values change. |
| 18614 | @end table |
| 18615 | |
| 18616 | The source and assembly windows show the current program position |
| 18617 | by highlighting the current line and marking it with a @samp{>} marker. |
| 18618 | Breakpoints are indicated with two markers. The first marker |
| 18619 | indicates the breakpoint type: |
| 18620 | |
| 18621 | @table @code |
| 18622 | @item B |
| 18623 | Breakpoint which was hit at least once. |
| 18624 | |
| 18625 | @item b |
| 18626 | Breakpoint which was never hit. |
| 18627 | |
| 18628 | @item H |
| 18629 | Hardware breakpoint which was hit at least once. |
| 18630 | |
| 18631 | @item h |
| 18632 | Hardware breakpoint which was never hit. |
| 18633 | @end table |
| 18634 | |
| 18635 | The second marker indicates whether the breakpoint is enabled or not: |
| 18636 | |
| 18637 | @table @code |
| 18638 | @item + |
| 18639 | Breakpoint is enabled. |
| 18640 | |
| 18641 | @item - |
| 18642 | Breakpoint is disabled. |
| 18643 | @end table |
| 18644 | |
| 18645 | The source, assembly and register windows are updated when the current |
| 18646 | thread changes, when the frame changes, or when the program counter |
| 18647 | changes. |
| 18648 | |
| 18649 | These windows are not all visible at the same time. The command |
| 18650 | window is always visible. The others can be arranged in several |
| 18651 | layouts: |
| 18652 | |
| 18653 | @itemize @bullet |
| 18654 | @item |
| 18655 | source only, |
| 18656 | |
| 18657 | @item |
| 18658 | assembly only, |
| 18659 | |
| 18660 | @item |
| 18661 | source and assembly, |
| 18662 | |
| 18663 | @item |
| 18664 | source and registers, or |
| 18665 | |
| 18666 | @item |
| 18667 | assembly and registers. |
| 18668 | @end itemize |
| 18669 | |
| 18670 | A status line above the command window shows the following information: |
| 18671 | |
| 18672 | @table @emph |
| 18673 | @item target |
| 18674 | Indicates the current @value{GDBN} target. |
| 18675 | (@pxref{Targets, ,Specifying a Debugging Target}). |
| 18676 | |
| 18677 | @item process |
| 18678 | Gives the current process or thread number. |
| 18679 | When no process is being debugged, this field is set to @code{No process}. |
| 18680 | |
| 18681 | @item function |
| 18682 | Gives the current function name for the selected frame. |
| 18683 | The name is demangled if demangling is turned on (@pxref{Print Settings}). |
| 18684 | When there is no symbol corresponding to the current program counter, |
| 18685 | the string @code{??} is displayed. |
| 18686 | |
| 18687 | @item line |
| 18688 | Indicates the current line number for the selected frame. |
| 18689 | When the current line number is not known, the string @code{??} is displayed. |
| 18690 | |
| 18691 | @item pc |
| 18692 | Indicates the current program counter address. |
| 18693 | @end table |
| 18694 | |
| 18695 | @node TUI Keys |
| 18696 | @section TUI Key Bindings |
| 18697 | @cindex TUI key bindings |
| 18698 | |
| 18699 | The TUI installs several key bindings in the readline keymaps |
| 18700 | (@pxref{Command Line Editing}). The following key bindings |
| 18701 | are installed for both TUI mode and the @value{GDBN} standard mode. |
| 18702 | |
| 18703 | @table @kbd |
| 18704 | @kindex C-x C-a |
| 18705 | @item C-x C-a |
| 18706 | @kindex C-x a |
| 18707 | @itemx C-x a |
| 18708 | @kindex C-x A |
| 18709 | @itemx C-x A |
| 18710 | Enter or leave the TUI mode. When leaving the TUI mode, |
| 18711 | the curses window management stops and @value{GDBN} operates using |
| 18712 | its standard mode, writing on the terminal directly. When reentering |
| 18713 | the TUI mode, control is given back to the curses windows. |
| 18714 | The screen is then refreshed. |
| 18715 | |
| 18716 | @kindex C-x 1 |
| 18717 | @item C-x 1 |
| 18718 | Use a TUI layout with only one window. The layout will |
| 18719 | either be @samp{source} or @samp{assembly}. When the TUI mode |
| 18720 | is not active, it will switch to the TUI mode. |
| 18721 | |
| 18722 | Think of this key binding as the Emacs @kbd{C-x 1} binding. |
| 18723 | |
| 18724 | @kindex C-x 2 |
| 18725 | @item C-x 2 |
| 18726 | Use a TUI layout with at least two windows. When the current |
| 18727 | layout already has two windows, the next layout with two windows is used. |
| 18728 | When a new layout is chosen, one window will always be common to the |
| 18729 | previous layout and the new one. |
| 18730 | |
| 18731 | Think of it as the Emacs @kbd{C-x 2} binding. |
| 18732 | |
| 18733 | @kindex C-x o |
| 18734 | @item C-x o |
| 18735 | Change the active window. The TUI associates several key bindings |
| 18736 | (like scrolling and arrow keys) with the active window. This command |
| 18737 | gives the focus to the next TUI window. |
| 18738 | |
| 18739 | Think of it as the Emacs @kbd{C-x o} binding. |
| 18740 | |
| 18741 | @kindex C-x s |
| 18742 | @item C-x s |
| 18743 | Switch in and out of the TUI SingleKey mode that binds single |
| 18744 | keys to @value{GDBN} commands (@pxref{TUI Single Key Mode}). |
| 18745 | @end table |
| 18746 | |
| 18747 | The following key bindings only work in the TUI mode: |
| 18748 | |
| 18749 | @table @asis |
| 18750 | @kindex PgUp |
| 18751 | @item @key{PgUp} |
| 18752 | Scroll the active window one page up. |
| 18753 | |
| 18754 | @kindex PgDn |
| 18755 | @item @key{PgDn} |
| 18756 | Scroll the active window one page down. |
| 18757 | |
| 18758 | @kindex Up |
| 18759 | @item @key{Up} |
| 18760 | Scroll the active window one line up. |
| 18761 | |
| 18762 | @kindex Down |
| 18763 | @item @key{Down} |
| 18764 | Scroll the active window one line down. |
| 18765 | |
| 18766 | @kindex Left |
| 18767 | @item @key{Left} |
| 18768 | Scroll the active window one column left. |
| 18769 | |
| 18770 | @kindex Right |
| 18771 | @item @key{Right} |
| 18772 | Scroll the active window one column right. |
| 18773 | |
| 18774 | @kindex C-L |
| 18775 | @item @kbd{C-L} |
| 18776 | Refresh the screen. |
| 18777 | @end table |
| 18778 | |
| 18779 | Because the arrow keys scroll the active window in the TUI mode, they |
| 18780 | are not available for their normal use by readline unless the command |
| 18781 | window has the focus. When another window is active, you must use |
| 18782 | other readline key bindings such as @kbd{C-p}, @kbd{C-n}, @kbd{C-b} |
| 18783 | and @kbd{C-f} to control the command window. |
| 18784 | |
| 18785 | @node TUI Single Key Mode |
| 18786 | @section TUI Single Key Mode |
| 18787 | @cindex TUI single key mode |
| 18788 | |
| 18789 | The TUI also provides a @dfn{SingleKey} mode, which binds several |
| 18790 | frequently used @value{GDBN} commands to single keys. Type @kbd{C-x s} to |
| 18791 | switch into this mode, where the following key bindings are used: |
| 18792 | |
| 18793 | @table @kbd |
| 18794 | @kindex c @r{(SingleKey TUI key)} |
| 18795 | @item c |
| 18796 | continue |
| 18797 | |
| 18798 | @kindex d @r{(SingleKey TUI key)} |
| 18799 | @item d |
| 18800 | down |
| 18801 | |
| 18802 | @kindex f @r{(SingleKey TUI key)} |
| 18803 | @item f |
| 18804 | finish |
| 18805 | |
| 18806 | @kindex n @r{(SingleKey TUI key)} |
| 18807 | @item n |
| 18808 | next |
| 18809 | |
| 18810 | @kindex q @r{(SingleKey TUI key)} |
| 18811 | @item q |
| 18812 | exit the SingleKey mode. |
| 18813 | |
| 18814 | @kindex r @r{(SingleKey TUI key)} |
| 18815 | @item r |
| 18816 | run |
| 18817 | |
| 18818 | @kindex s @r{(SingleKey TUI key)} |
| 18819 | @item s |
| 18820 | step |
| 18821 | |
| 18822 | @kindex u @r{(SingleKey TUI key)} |
| 18823 | @item u |
| 18824 | up |
| 18825 | |
| 18826 | @kindex v @r{(SingleKey TUI key)} |
| 18827 | @item v |
| 18828 | info locals |
| 18829 | |
| 18830 | @kindex w @r{(SingleKey TUI key)} |
| 18831 | @item w |
| 18832 | where |
| 18833 | @end table |
| 18834 | |
| 18835 | Other keys temporarily switch to the @value{GDBN} command prompt. |
| 18836 | The key that was pressed is inserted in the editing buffer so that |
| 18837 | it is possible to type most @value{GDBN} commands without interaction |
| 18838 | with the TUI SingleKey mode. Once the command is entered the TUI |
| 18839 | SingleKey mode is restored. The only way to permanently leave |
| 18840 | this mode is by typing @kbd{q} or @kbd{C-x s}. |
| 18841 | |
| 18842 | |
| 18843 | @node TUI Commands |
| 18844 | @section TUI-specific Commands |
| 18845 | @cindex TUI commands |
| 18846 | |
| 18847 | The TUI has specific commands to control the text windows. |
| 18848 | These commands are always available, even when @value{GDBN} is not in |
| 18849 | the TUI mode. When @value{GDBN} is in the standard mode, most |
| 18850 | of these commands will automatically switch to the TUI mode. |
| 18851 | |
| 18852 | @table @code |
| 18853 | @item info win |
| 18854 | @kindex info win |
| 18855 | List and give the size of all displayed windows. |
| 18856 | |
| 18857 | @item layout next |
| 18858 | @kindex layout |
| 18859 | Display the next layout. |
| 18860 | |
| 18861 | @item layout prev |
| 18862 | Display the previous layout. |
| 18863 | |
| 18864 | @item layout src |
| 18865 | Display the source window only. |
| 18866 | |
| 18867 | @item layout asm |
| 18868 | Display the assembly window only. |
| 18869 | |
| 18870 | @item layout split |
| 18871 | Display the source and assembly window. |
| 18872 | |
| 18873 | @item layout regs |
| 18874 | Display the register window together with the source or assembly window. |
| 18875 | |
| 18876 | @item focus next |
| 18877 | @kindex focus |
| 18878 | Make the next window active for scrolling. |
| 18879 | |
| 18880 | @item focus prev |
| 18881 | Make the previous window active for scrolling. |
| 18882 | |
| 18883 | @item focus src |
| 18884 | Make the source window active for scrolling. |
| 18885 | |
| 18886 | @item focus asm |
| 18887 | Make the assembly window active for scrolling. |
| 18888 | |
| 18889 | @item focus regs |
| 18890 | Make the register window active for scrolling. |
| 18891 | |
| 18892 | @item focus cmd |
| 18893 | Make the command window active for scrolling. |
| 18894 | |
| 18895 | @item refresh |
| 18896 | @kindex refresh |
| 18897 | Refresh the screen. This is similar to typing @kbd{C-L}. |
| 18898 | |
| 18899 | @item tui reg float |
| 18900 | @kindex tui reg |
| 18901 | Show the floating point registers in the register window. |
| 18902 | |
| 18903 | @item tui reg general |
| 18904 | Show the general registers in the register window. |
| 18905 | |
| 18906 | @item tui reg next |
| 18907 | Show the next register group. The list of register groups as well as |
| 18908 | their order is target specific. The predefined register groups are the |
| 18909 | following: @code{general}, @code{float}, @code{system}, @code{vector}, |
| 18910 | @code{all}, @code{save}, @code{restore}. |
| 18911 | |
| 18912 | @item tui reg system |
| 18913 | Show the system registers in the register window. |
| 18914 | |
| 18915 | @item update |
| 18916 | @kindex update |
| 18917 | Update the source window and the current execution point. |
| 18918 | |
| 18919 | @item winheight @var{name} +@var{count} |
| 18920 | @itemx winheight @var{name} -@var{count} |
| 18921 | @kindex winheight |
| 18922 | Change the height of the window @var{name} by @var{count} |
| 18923 | lines. Positive counts increase the height, while negative counts |
| 18924 | decrease it. |
| 18925 | |
| 18926 | @item tabset @var{nchars} |
| 18927 | @kindex tabset |
| 18928 | Set the width of tab stops to be @var{nchars} characters. |
| 18929 | @end table |
| 18930 | |
| 18931 | @node TUI Configuration |
| 18932 | @section TUI Configuration Variables |
| 18933 | @cindex TUI configuration variables |
| 18934 | |
| 18935 | Several configuration variables control the appearance of TUI windows. |
| 18936 | |
| 18937 | @table @code |
| 18938 | @item set tui border-kind @var{kind} |
| 18939 | @kindex set tui border-kind |
| 18940 | Select the border appearance for the source, assembly and register windows. |
| 18941 | The possible values are the following: |
| 18942 | @table @code |
| 18943 | @item space |
| 18944 | Use a space character to draw the border. |
| 18945 | |
| 18946 | @item ascii |
| 18947 | Use @sc{ascii} characters @samp{+}, @samp{-} and @samp{|} to draw the border. |
| 18948 | |
| 18949 | @item acs |
| 18950 | Use the Alternate Character Set to draw the border. The border is |
| 18951 | drawn using character line graphics if the terminal supports them. |
| 18952 | @end table |
| 18953 | |
| 18954 | @item set tui border-mode @var{mode} |
| 18955 | @kindex set tui border-mode |
| 18956 | @itemx set tui active-border-mode @var{mode} |
| 18957 | @kindex set tui active-border-mode |
| 18958 | Select the display attributes for the borders of the inactive windows |
| 18959 | or the active window. The @var{mode} can be one of the following: |
| 18960 | @table @code |
| 18961 | @item normal |
| 18962 | Use normal attributes to display the border. |
| 18963 | |
| 18964 | @item standout |
| 18965 | Use standout mode. |
| 18966 | |
| 18967 | @item reverse |
| 18968 | Use reverse video mode. |
| 18969 | |
| 18970 | @item half |
| 18971 | Use half bright mode. |
| 18972 | |
| 18973 | @item half-standout |
| 18974 | Use half bright and standout mode. |
| 18975 | |
| 18976 | @item bold |
| 18977 | Use extra bright or bold mode. |
| 18978 | |
| 18979 | @item bold-standout |
| 18980 | Use extra bright or bold and standout mode. |
| 18981 | @end table |
| 18982 | @end table |
| 18983 | |
| 18984 | @node Emacs |
| 18985 | @chapter Using @value{GDBN} under @sc{gnu} Emacs |
| 18986 | |
| 18987 | @cindex Emacs |
| 18988 | @cindex @sc{gnu} Emacs |
| 18989 | A special interface allows you to use @sc{gnu} Emacs to view (and |
| 18990 | edit) the source files for the program you are debugging with |
| 18991 | @value{GDBN}. |
| 18992 | |
| 18993 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the |
| 18994 | executable file you want to debug as an argument. This command starts |
| 18995 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly |
| 18996 | created Emacs buffer. |
| 18997 | @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.) |
| 18998 | |
| 18999 | Running @value{GDBN} under Emacs can be just like running @value{GDBN} normally except for two |
| 19000 | things: |
| 19001 | |
| 19002 | @itemize @bullet |
| 19003 | @item |
| 19004 | All ``terminal'' input and output goes through an Emacs buffer, called |
| 19005 | the GUD buffer. |
| 19006 | |
| 19007 | This applies both to @value{GDBN} commands and their output, and to the input |
| 19008 | and output done by the program you are debugging. |
| 19009 | |
| 19010 | This is useful because it means that you can copy the text of previous |
| 19011 | commands and input them again; you can even use parts of the output |
| 19012 | in this way. |
| 19013 | |
| 19014 | All the facilities of Emacs' Shell mode are available for interacting |
| 19015 | with your program. In particular, you can send signals the usual |
| 19016 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a |
| 19017 | stop. |
| 19018 | |
| 19019 | @item |
| 19020 | @value{GDBN} displays source code through Emacs. |
| 19021 | |
| 19022 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the |
| 19023 | source file for that frame and puts an arrow (@samp{=>}) at the |
| 19024 | left margin of the current line. Emacs uses a separate buffer for |
| 19025 | source display, and splits the screen to show both your @value{GDBN} session |
| 19026 | and the source. |
| 19027 | |
| 19028 | Explicit @value{GDBN} @code{list} or search commands still produce output as |
| 19029 | usual, but you probably have no reason to use them from Emacs. |
| 19030 | @end itemize |
| 19031 | |
| 19032 | We call this @dfn{text command mode}. Emacs 22.1, and later, also uses |
| 19033 | a graphical mode, enabled by default, which provides further buffers |
| 19034 | that can control the execution and describe the state of your program. |
| 19035 | @xref{GDB Graphical Interface,,, Emacs, The @sc{gnu} Emacs Manual}. |
| 19036 | |
| 19037 | If you specify an absolute file name when prompted for the @kbd{M-x |
| 19038 | gdb} argument, then Emacs sets your current working directory to where |
| 19039 | your program resides. If you only specify the file name, then Emacs |
| 19040 | sets your current working directory to to the directory associated |
| 19041 | with the previous buffer. In this case, @value{GDBN} may find your |
| 19042 | program by searching your environment's @code{PATH} variable, but on |
| 19043 | some operating systems it might not find the source. So, although the |
| 19044 | @value{GDBN} input and output session proceeds normally, the auxiliary |
| 19045 | buffer does not display the current source and line of execution. |
| 19046 | |
| 19047 | The initial working directory of @value{GDBN} is printed on the top |
| 19048 | line of the GUD buffer and this serves as a default for the commands |
| 19049 | that specify files for @value{GDBN} to operate on. @xref{Files, |
| 19050 | ,Commands to Specify Files}. |
| 19051 | |
| 19052 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If you |
| 19053 | need to call @value{GDBN} by a different name (for example, if you |
| 19054 | keep several configurations around, with different names) you can |
| 19055 | customize the Emacs variable @code{gud-gdb-command-name} to run the |
| 19056 | one you want. |
| 19057 | |
| 19058 | In the GUD buffer, you can use these special Emacs commands in |
| 19059 | addition to the standard Shell mode commands: |
| 19060 | |
| 19061 | @table @kbd |
| 19062 | @item C-h m |
| 19063 | Describe the features of Emacs' GUD Mode. |
| 19064 | |
| 19065 | @item C-c C-s |
| 19066 | Execute to another source line, like the @value{GDBN} @code{step} command; also |
| 19067 | update the display window to show the current file and location. |
| 19068 | |
| 19069 | @item C-c C-n |
| 19070 | Execute to next source line in this function, skipping all function |
| 19071 | calls, like the @value{GDBN} @code{next} command. Then update the display window |
| 19072 | to show the current file and location. |
| 19073 | |
| 19074 | @item C-c C-i |
| 19075 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update |
| 19076 | display window accordingly. |
| 19077 | |
| 19078 | @item C-c C-f |
| 19079 | Execute until exit from the selected stack frame, like the @value{GDBN} |
| 19080 | @code{finish} command. |
| 19081 | |
| 19082 | @item C-c C-r |
| 19083 | Continue execution of your program, like the @value{GDBN} @code{continue} |
| 19084 | command. |
| 19085 | |
| 19086 | @item C-c < |
| 19087 | Go up the number of frames indicated by the numeric argument |
| 19088 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), |
| 19089 | like the @value{GDBN} @code{up} command. |
| 19090 | |
| 19091 | @item C-c > |
| 19092 | Go down the number of frames indicated by the numeric argument, like the |
| 19093 | @value{GDBN} @code{down} command. |
| 19094 | @end table |
| 19095 | |
| 19096 | In any source file, the Emacs command @kbd{C-x @key{SPC}} (@code{gud-break}) |
| 19097 | tells @value{GDBN} to set a breakpoint on the source line point is on. |
| 19098 | |
| 19099 | In text command mode, if you type @kbd{M-x speedbar}, Emacs displays a |
| 19100 | separate frame which shows a backtrace when the GUD buffer is current. |
| 19101 | Move point to any frame in the stack and type @key{RET} to make it |
| 19102 | become the current frame and display the associated source in the |
| 19103 | source buffer. Alternatively, click @kbd{Mouse-2} to make the |
| 19104 | selected frame become the current one. In graphical mode, the |
| 19105 | speedbar displays watch expressions. |
| 19106 | |
| 19107 | If you accidentally delete the source-display buffer, an easy way to get |
| 19108 | it back is to type the command @code{f} in the @value{GDBN} buffer, to |
| 19109 | request a frame display; when you run under Emacs, this recreates |
| 19110 | the source buffer if necessary to show you the context of the current |
| 19111 | frame. |
| 19112 | |
| 19113 | The source files displayed in Emacs are in ordinary Emacs buffers |
| 19114 | which are visiting the source files in the usual way. You can edit |
| 19115 | the files with these buffers if you wish; but keep in mind that @value{GDBN} |
| 19116 | communicates with Emacs in terms of line numbers. If you add or |
| 19117 | delete lines from the text, the line numbers that @value{GDBN} knows cease |
| 19118 | to correspond properly with the code. |
| 19119 | |
| 19120 | A more detailed description of Emacs' interaction with @value{GDBN} is |
| 19121 | given in the Emacs manual (@pxref{Debuggers,,, Emacs, The @sc{gnu} |
| 19122 | Emacs Manual}). |
| 19123 | |
| 19124 | @c The following dropped because Epoch is nonstandard. Reactivate |
| 19125 | @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990 |
| 19126 | @ignore |
| 19127 | @kindex Emacs Epoch environment |
| 19128 | @kindex Epoch |
| 19129 | @kindex inspect |
| 19130 | |
| 19131 | Version 18 of @sc{gnu} Emacs has a built-in window system |
| 19132 | called the @code{epoch} |
| 19133 | environment. Users of this environment can use a new command, |
| 19134 | @code{inspect} which performs identically to @code{print} except that |
| 19135 | each value is printed in its own window. |
| 19136 | @end ignore |
| 19137 | |
| 19138 | |
| 19139 | @node GDB/MI |
| 19140 | @chapter The @sc{gdb/mi} Interface |
| 19141 | |
| 19142 | @unnumberedsec Function and Purpose |
| 19143 | |
| 19144 | @cindex @sc{gdb/mi}, its purpose |
| 19145 | @sc{gdb/mi} is a line based machine oriented text interface to |
| 19146 | @value{GDBN} and is activated by specifying using the |
| 19147 | @option{--interpreter} command line option (@pxref{Mode Options}). It |
| 19148 | is specifically intended to support the development of systems which |
| 19149 | use the debugger as just one small component of a larger system. |
| 19150 | |
| 19151 | This chapter is a specification of the @sc{gdb/mi} interface. It is written |
| 19152 | in the form of a reference manual. |
| 19153 | |
| 19154 | Note that @sc{gdb/mi} is still under construction, so some of the |
| 19155 | features described below are incomplete and subject to change |
| 19156 | (@pxref{GDB/MI Development and Front Ends, , @sc{gdb/mi} Development and Front Ends}). |
| 19157 | |
| 19158 | @unnumberedsec Notation and Terminology |
| 19159 | |
| 19160 | @cindex notational conventions, for @sc{gdb/mi} |
| 19161 | This chapter uses the following notation: |
| 19162 | |
| 19163 | @itemize @bullet |
| 19164 | @item |
| 19165 | @code{|} separates two alternatives. |
| 19166 | |
| 19167 | @item |
| 19168 | @code{[ @var{something} ]} indicates that @var{something} is optional: |
| 19169 | it may or may not be given. |
| 19170 | |
| 19171 | @item |
| 19172 | @code{( @var{group} )*} means that @var{group} inside the parentheses |
| 19173 | may repeat zero or more times. |
| 19174 | |
| 19175 | @item |
| 19176 | @code{( @var{group} )+} means that @var{group} inside the parentheses |
| 19177 | may repeat one or more times. |
| 19178 | |
| 19179 | @item |
| 19180 | @code{"@var{string}"} means a literal @var{string}. |
| 19181 | @end itemize |
| 19182 | |
| 19183 | @ignore |
| 19184 | @heading Dependencies |
| 19185 | @end ignore |
| 19186 | |
| 19187 | @menu |
| 19188 | * GDB/MI General Design:: |
| 19189 | * GDB/MI Command Syntax:: |
| 19190 | * GDB/MI Compatibility with CLI:: |
| 19191 | * GDB/MI Development and Front Ends:: |
| 19192 | * GDB/MI Output Records:: |
| 19193 | * GDB/MI Simple Examples:: |
| 19194 | * GDB/MI Command Description Format:: |
| 19195 | * GDB/MI Breakpoint Commands:: |
| 19196 | * GDB/MI Program Context:: |
| 19197 | * GDB/MI Thread Commands:: |
| 19198 | * GDB/MI Program Execution:: |
| 19199 | * GDB/MI Stack Manipulation:: |
| 19200 | * GDB/MI Variable Objects:: |
| 19201 | * GDB/MI Data Manipulation:: |
| 19202 | * GDB/MI Tracepoint Commands:: |
| 19203 | * GDB/MI Symbol Query:: |
| 19204 | * GDB/MI File Commands:: |
| 19205 | @ignore |
| 19206 | * GDB/MI Kod Commands:: |
| 19207 | * GDB/MI Memory Overlay Commands:: |
| 19208 | * GDB/MI Signal Handling Commands:: |
| 19209 | @end ignore |
| 19210 | * GDB/MI Target Manipulation:: |
| 19211 | * GDB/MI File Transfer Commands:: |
| 19212 | * GDB/MI Miscellaneous Commands:: |
| 19213 | @end menu |
| 19214 | |
| 19215 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19216 | @node GDB/MI General Design |
| 19217 | @section @sc{gdb/mi} General Design |
| 19218 | @cindex GDB/MI General Design |
| 19219 | |
| 19220 | Interaction of a @sc{GDB/MI} frontend with @value{GDBN} involves three |
| 19221 | parts---commands sent to @value{GDBN}, responses to those commands |
| 19222 | and notifications. Each command results in exactly one response, |
| 19223 | indicating either successful completion of the command, or an error. |
| 19224 | For the commands that do not resume the target, the response contains the |
| 19225 | requested information. For the commands that resume the target, the |
| 19226 | response only indicates whether the target was successfully resumed. |
| 19227 | Notifications is the mechanism for reporting changes in the state of the |
| 19228 | target, or in @value{GDBN} state, that cannot conveniently be associated with |
| 19229 | a command and reported as part of that command response. |
| 19230 | |
| 19231 | The important examples of notifications are: |
| 19232 | @itemize @bullet |
| 19233 | |
| 19234 | @item |
| 19235 | Exec notifications. These are used to report changes in |
| 19236 | target state---when a target is resumed, or stopped. It would not |
| 19237 | be feasible to include this information in response of resuming |
| 19238 | commands, because one resume commands can result in multiple events in |
| 19239 | different threads. Also, quite some time may pass before any event |
| 19240 | happens in the target, while a frontend needs to know whether the resuming |
| 19241 | command itself was successfully executed. |
| 19242 | |
| 19243 | @item |
| 19244 | Console output, and status notifications. Console output |
| 19245 | notifications are used to report output of CLI commands, as well as |
| 19246 | diagnostics for other commands. Status notifications are used to |
| 19247 | report the progress of a long-running operation. Naturally, including |
| 19248 | this information in command response would mean no output is produced |
| 19249 | until the command is finished, which is undesirable. |
| 19250 | |
| 19251 | @item |
| 19252 | General notifications. Commands may have various side effects on |
| 19253 | the @value{GDBN} or target state beyond their official purpose. For example, |
| 19254 | a command may change the selected thread. Although such changes can |
| 19255 | be included in command response, using notification allows for more |
| 19256 | orthogonal frontend design. |
| 19257 | |
| 19258 | @end itemize |
| 19259 | |
| 19260 | There's no guarantee that whenever an MI command reports an error, |
| 19261 | @value{GDBN} or the target are in any specific state, and especially, |
| 19262 | the state is not reverted to the state before the MI command was |
| 19263 | processed. Therefore, whenever an MI command results in an error, |
| 19264 | we recommend that the frontend refreshes all the information shown in |
| 19265 | the user interface. |
| 19266 | |
| 19267 | @subsection Context management |
| 19268 | |
| 19269 | In most cases when @value{GDBN} accesses the target, this access is |
| 19270 | done in context of a specific thread and frame (@pxref{Frames}). |
| 19271 | Often, even when accessing global data, the target requires that a thread |
| 19272 | be specified. The CLI interface maintains the selected thread and frame, |
| 19273 | and supplies them to target on each command. This is convenient, |
| 19274 | because a command line user would not want to specify that information |
| 19275 | explicitly on each command, and because user interacts with |
| 19276 | @value{GDBN} via a single terminal, so no confusion is possible as |
| 19277 | to what thread and frame are the current ones. |
| 19278 | |
| 19279 | In the case of MI, the concept of selected thread and frame is less |
| 19280 | useful. First, a frontend can easily remember this information |
| 19281 | itself. Second, a graphical frontend can have more than one window, |
| 19282 | each one used for debugging a different thread, and the frontend might |
| 19283 | want to access additional threads for internal purposes. This |
| 19284 | increases the risk that by relying on implicitly selected thread, the |
| 19285 | frontend may be operating on a wrong one. Therefore, each MI command |
| 19286 | should explicitly specify which thread and frame to operate on. To |
| 19287 | make it possible, each MI command accepts the @samp{--thread} and |
| 19288 | @samp{--frame} options, the value to each is @value{GDBN} identifier |
| 19289 | for thread and frame to operate on. |
| 19290 | |
| 19291 | Usually, each top-level window in a frontend allows the user to select |
| 19292 | a thread and a frame, and remembers the user selection for further |
| 19293 | operations. However, in some cases @value{GDBN} may suggest that the |
| 19294 | current thread be changed. For example, when stopping on a breakpoint |
| 19295 | it is reasonable to switch to the thread where breakpoint is hit. For |
| 19296 | another example, if the user issues the CLI @samp{thread} command via |
| 19297 | the frontend, it is desirable to change the frontend's selected thread to the |
| 19298 | one specified by user. @value{GDBN} communicates the suggestion to |
| 19299 | change current thread using the @samp{=thread-selected} notification. |
| 19300 | No such notification is available for the selected frame at the moment. |
| 19301 | |
| 19302 | Note that historically, MI shares the selected thread with CLI, so |
| 19303 | frontends used the @code{-thread-select} to execute commands in the |
| 19304 | right context. However, getting this to work right is cumbersome. The |
| 19305 | simplest way is for frontend to emit @code{-thread-select} command |
| 19306 | before every command. This doubles the number of commands that need |
| 19307 | to be sent. The alternative approach is to suppress @code{-thread-select} |
| 19308 | if the selected thread in @value{GDBN} is supposed to be identical to the |
| 19309 | thread the frontend wants to operate on. However, getting this |
| 19310 | optimization right can be tricky. In particular, if the frontend |
| 19311 | sends several commands to @value{GDBN}, and one of the commands changes the |
| 19312 | selected thread, then the behaviour of subsequent commands will |
| 19313 | change. So, a frontend should either wait for response from such |
| 19314 | problematic commands, or explicitly add @code{-thread-select} for |
| 19315 | all subsequent commands. No frontend is known to do this exactly |
| 19316 | right, so it is suggested to just always pass the @samp{--thread} and |
| 19317 | @samp{--frame} options. |
| 19318 | |
| 19319 | @subsection Asynchronous command execution and non-stop mode |
| 19320 | |
| 19321 | On some targets, @value{GDBN} is capable of processing MI commands |
| 19322 | even while the target is running. This is called @dfn{asynchronous |
| 19323 | command execution} (@pxref{Background Execution}). The frontend may |
| 19324 | specify a preferrence for asynchronous execution using the |
| 19325 | @code{-gdb-set target-async 1} command, which should be emitted before |
| 19326 | either running the executable or attaching to the target. After the |
| 19327 | frontend has started the executable or attached to the target, it can |
| 19328 | find if asynchronous execution is enabled using the |
| 19329 | @code{-list-target-features} command. |
| 19330 | |
| 19331 | Even if @value{GDBN} can accept a command while target is running, |
| 19332 | many commands that access the target do not work when the target is |
| 19333 | running. Therefore, asynchronous command execution is most useful |
| 19334 | when combined with non-stop mode (@pxref{Non-Stop Mode}). Then, |
| 19335 | it is possible to examine the state of one thread, while other threads |
| 19336 | are running. |
| 19337 | |
| 19338 | When a given thread is running, MI commands that try to access the |
| 19339 | target in the context of that thread may not work, or may work only on |
| 19340 | some targets. In particular, commands that try to operate on thread's |
| 19341 | stack will not work, on any target. Commands that read memory, or |
| 19342 | modify breakpoints, may work or not work, depending on the target. Note |
| 19343 | that even commands that operate on global state, such as @code{print}, |
| 19344 | @code{set}, and breakpoint commands, still access the target in the |
| 19345 | context of a specific thread, so frontend should try to find a |
| 19346 | stopped thread and perform the operation on that thread (using the |
| 19347 | @samp{--thread} option). |
| 19348 | |
| 19349 | Which commands will work in the context of a running thread is |
| 19350 | highly target dependent. However, the two commands |
| 19351 | @code{-exec-interrupt}, to stop a thread, and @code{-thread-info}, |
| 19352 | to find the state of a thread, will always work. |
| 19353 | |
| 19354 | @subsection Thread groups |
| 19355 | @value{GDBN} may be used to debug several processes at the same time. |
| 19356 | On some platfroms, @value{GDBN} may support debugging of several |
| 19357 | hardware systems, each one having several cores with several different |
| 19358 | processes running on each core. This section describes the MI |
| 19359 | mechanism to support such debugging scenarios. |
| 19360 | |
| 19361 | The key observation is that regardless of the structure of the |
| 19362 | target, MI can have a global list of threads, because most commands that |
| 19363 | accept the @samp{--thread} option do not need to know what process that |
| 19364 | thread belongs to. Therefore, it is not necessary to introduce |
| 19365 | neither additional @samp{--process} option, nor an notion of the |
| 19366 | current process in the MI interface. The only strictly new feature |
| 19367 | that is required is the ability to find how the threads are grouped |
| 19368 | into processes. |
| 19369 | |
| 19370 | To allow the user to discover such grouping, and to support arbitrary |
| 19371 | hierarchy of machines/cores/processes, MI introduces the concept of a |
| 19372 | @dfn{thread group}. Thread group is a collection of threads and other |
| 19373 | thread groups. A thread group always has a string identifier, a type, |
| 19374 | and may have additional attributes specific to the type. A new |
| 19375 | command, @code{-list-thread-groups}, returns the list of top-level |
| 19376 | thread groups, which correspond to processes that @value{GDBN} is |
| 19377 | debugging at the moment. By passing an identifier of a thread group |
| 19378 | to the @code{-list-thread-groups} command, it is possible to obtain |
| 19379 | the members of specific thread group. |
| 19380 | |
| 19381 | To allow the user to easily discover processes, and other objects, he |
| 19382 | wishes to debug, a concept of @dfn{available thread group} is |
| 19383 | introduced. Available thread group is an thread group that |
| 19384 | @value{GDBN} is not debugging, but that can be attached to, using the |
| 19385 | @code{-target-attach} command. The list of available top-level thread |
| 19386 | groups can be obtained using @samp{-list-thread-groups --available}. |
| 19387 | In general, the content of a thread group may be only retrieved only |
| 19388 | after attaching to that thread group. |
| 19389 | |
| 19390 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19391 | @node GDB/MI Command Syntax |
| 19392 | @section @sc{gdb/mi} Command Syntax |
| 19393 | |
| 19394 | @menu |
| 19395 | * GDB/MI Input Syntax:: |
| 19396 | * GDB/MI Output Syntax:: |
| 19397 | @end menu |
| 19398 | |
| 19399 | @node GDB/MI Input Syntax |
| 19400 | @subsection @sc{gdb/mi} Input Syntax |
| 19401 | |
| 19402 | @cindex input syntax for @sc{gdb/mi} |
| 19403 | @cindex @sc{gdb/mi}, input syntax |
| 19404 | @table @code |
| 19405 | @item @var{command} @expansion{} |
| 19406 | @code{@var{cli-command} | @var{mi-command}} |
| 19407 | |
| 19408 | @item @var{cli-command} @expansion{} |
| 19409 | @code{[ @var{token} ] @var{cli-command} @var{nl}}, where |
| 19410 | @var{cli-command} is any existing @value{GDBN} CLI command. |
| 19411 | |
| 19412 | @item @var{mi-command} @expansion{} |
| 19413 | @code{[ @var{token} ] "-" @var{operation} ( " " @var{option} )* |
| 19414 | @code{[} " --" @code{]} ( " " @var{parameter} )* @var{nl}} |
| 19415 | |
| 19416 | @item @var{token} @expansion{} |
| 19417 | "any sequence of digits" |
| 19418 | |
| 19419 | @item @var{option} @expansion{} |
| 19420 | @code{"-" @var{parameter} [ " " @var{parameter} ]} |
| 19421 | |
| 19422 | @item @var{parameter} @expansion{} |
| 19423 | @code{@var{non-blank-sequence} | @var{c-string}} |
| 19424 | |
| 19425 | @item @var{operation} @expansion{} |
| 19426 | @emph{any of the operations described in this chapter} |
| 19427 | |
| 19428 | @item @var{non-blank-sequence} @expansion{} |
| 19429 | @emph{anything, provided it doesn't contain special characters such as |
| 19430 | "-", @var{nl}, """ and of course " "} |
| 19431 | |
| 19432 | @item @var{c-string} @expansion{} |
| 19433 | @code{""" @var{seven-bit-iso-c-string-content} """} |
| 19434 | |
| 19435 | @item @var{nl} @expansion{} |
| 19436 | @code{CR | CR-LF} |
| 19437 | @end table |
| 19438 | |
| 19439 | @noindent |
| 19440 | Notes: |
| 19441 | |
| 19442 | @itemize @bullet |
| 19443 | @item |
| 19444 | The CLI commands are still handled by the @sc{mi} interpreter; their |
| 19445 | output is described below. |
| 19446 | |
| 19447 | @item |
| 19448 | The @code{@var{token}}, when present, is passed back when the command |
| 19449 | finishes. |
| 19450 | |
| 19451 | @item |
| 19452 | Some @sc{mi} commands accept optional arguments as part of the parameter |
| 19453 | list. Each option is identified by a leading @samp{-} (dash) and may be |
| 19454 | followed by an optional argument parameter. Options occur first in the |
| 19455 | parameter list and can be delimited from normal parameters using |
| 19456 | @samp{--} (this is useful when some parameters begin with a dash). |
| 19457 | @end itemize |
| 19458 | |
| 19459 | Pragmatics: |
| 19460 | |
| 19461 | @itemize @bullet |
| 19462 | @item |
| 19463 | We want easy access to the existing CLI syntax (for debugging). |
| 19464 | |
| 19465 | @item |
| 19466 | We want it to be easy to spot a @sc{mi} operation. |
| 19467 | @end itemize |
| 19468 | |
| 19469 | @node GDB/MI Output Syntax |
| 19470 | @subsection @sc{gdb/mi} Output Syntax |
| 19471 | |
| 19472 | @cindex output syntax of @sc{gdb/mi} |
| 19473 | @cindex @sc{gdb/mi}, output syntax |
| 19474 | The output from @sc{gdb/mi} consists of zero or more out-of-band records |
| 19475 | followed, optionally, by a single result record. This result record |
| 19476 | is for the most recent command. The sequence of output records is |
| 19477 | terminated by @samp{(gdb)}. |
| 19478 | |
| 19479 | If an input command was prefixed with a @code{@var{token}} then the |
| 19480 | corresponding output for that command will also be prefixed by that same |
| 19481 | @var{token}. |
| 19482 | |
| 19483 | @table @code |
| 19484 | @item @var{output} @expansion{} |
| 19485 | @code{( @var{out-of-band-record} )* [ @var{result-record} ] "(gdb)" @var{nl}} |
| 19486 | |
| 19487 | @item @var{result-record} @expansion{} |
| 19488 | @code{ [ @var{token} ] "^" @var{result-class} ( "," @var{result} )* @var{nl}} |
| 19489 | |
| 19490 | @item @var{out-of-band-record} @expansion{} |
| 19491 | @code{@var{async-record} | @var{stream-record}} |
| 19492 | |
| 19493 | @item @var{async-record} @expansion{} |
| 19494 | @code{@var{exec-async-output} | @var{status-async-output} | @var{notify-async-output}} |
| 19495 | |
| 19496 | @item @var{exec-async-output} @expansion{} |
| 19497 | @code{[ @var{token} ] "*" @var{async-output}} |
| 19498 | |
| 19499 | @item @var{status-async-output} @expansion{} |
| 19500 | @code{[ @var{token} ] "+" @var{async-output}} |
| 19501 | |
| 19502 | @item @var{notify-async-output} @expansion{} |
| 19503 | @code{[ @var{token} ] "=" @var{async-output}} |
| 19504 | |
| 19505 | @item @var{async-output} @expansion{} |
| 19506 | @code{@var{async-class} ( "," @var{result} )* @var{nl}} |
| 19507 | |
| 19508 | @item @var{result-class} @expansion{} |
| 19509 | @code{"done" | "running" | "connected" | "error" | "exit"} |
| 19510 | |
| 19511 | @item @var{async-class} @expansion{} |
| 19512 | @code{"stopped" | @var{others}} (where @var{others} will be added |
| 19513 | depending on the needs---this is still in development). |
| 19514 | |
| 19515 | @item @var{result} @expansion{} |
| 19516 | @code{ @var{variable} "=" @var{value}} |
| 19517 | |
| 19518 | @item @var{variable} @expansion{} |
| 19519 | @code{ @var{string} } |
| 19520 | |
| 19521 | @item @var{value} @expansion{} |
| 19522 | @code{ @var{const} | @var{tuple} | @var{list} } |
| 19523 | |
| 19524 | @item @var{const} @expansion{} |
| 19525 | @code{@var{c-string}} |
| 19526 | |
| 19527 | @item @var{tuple} @expansion{} |
| 19528 | @code{ "@{@}" | "@{" @var{result} ( "," @var{result} )* "@}" } |
| 19529 | |
| 19530 | @item @var{list} @expansion{} |
| 19531 | @code{ "[]" | "[" @var{value} ( "," @var{value} )* "]" | "[" |
| 19532 | @var{result} ( "," @var{result} )* "]" } |
| 19533 | |
| 19534 | @item @var{stream-record} @expansion{} |
| 19535 | @code{@var{console-stream-output} | @var{target-stream-output} | @var{log-stream-output}} |
| 19536 | |
| 19537 | @item @var{console-stream-output} @expansion{} |
| 19538 | @code{"~" @var{c-string}} |
| 19539 | |
| 19540 | @item @var{target-stream-output} @expansion{} |
| 19541 | @code{"@@" @var{c-string}} |
| 19542 | |
| 19543 | @item @var{log-stream-output} @expansion{} |
| 19544 | @code{"&" @var{c-string}} |
| 19545 | |
| 19546 | @item @var{nl} @expansion{} |
| 19547 | @code{CR | CR-LF} |
| 19548 | |
| 19549 | @item @var{token} @expansion{} |
| 19550 | @emph{any sequence of digits}. |
| 19551 | @end table |
| 19552 | |
| 19553 | @noindent |
| 19554 | Notes: |
| 19555 | |
| 19556 | @itemize @bullet |
| 19557 | @item |
| 19558 | All output sequences end in a single line containing a period. |
| 19559 | |
| 19560 | @item |
| 19561 | The @code{@var{token}} is from the corresponding request. Note that |
| 19562 | for all async output, while the token is allowed by the grammar and |
| 19563 | may be output by future versions of @value{GDBN} for select async |
| 19564 | output messages, it is generally omitted. Frontends should treat |
| 19565 | all async output as reporting general changes in the state of the |
| 19566 | target and there should be no need to associate async output to any |
| 19567 | prior command. |
| 19568 | |
| 19569 | @item |
| 19570 | @cindex status output in @sc{gdb/mi} |
| 19571 | @var{status-async-output} contains on-going status information about the |
| 19572 | progress of a slow operation. It can be discarded. All status output is |
| 19573 | prefixed by @samp{+}. |
| 19574 | |
| 19575 | @item |
| 19576 | @cindex async output in @sc{gdb/mi} |
| 19577 | @var{exec-async-output} contains asynchronous state change on the target |
| 19578 | (stopped, started, disappeared). All async output is prefixed by |
| 19579 | @samp{*}. |
| 19580 | |
| 19581 | @item |
| 19582 | @cindex notify output in @sc{gdb/mi} |
| 19583 | @var{notify-async-output} contains supplementary information that the |
| 19584 | client should handle (e.g., a new breakpoint information). All notify |
| 19585 | output is prefixed by @samp{=}. |
| 19586 | |
| 19587 | @item |
| 19588 | @cindex console output in @sc{gdb/mi} |
| 19589 | @var{console-stream-output} is output that should be displayed as is in the |
| 19590 | console. It is the textual response to a CLI command. All the console |
| 19591 | output is prefixed by @samp{~}. |
| 19592 | |
| 19593 | @item |
| 19594 | @cindex target output in @sc{gdb/mi} |
| 19595 | @var{target-stream-output} is the output produced by the target program. |
| 19596 | All the target output is prefixed by @samp{@@}. |
| 19597 | |
| 19598 | @item |
| 19599 | @cindex log output in @sc{gdb/mi} |
| 19600 | @var{log-stream-output} is output text coming from @value{GDBN}'s internals, for |
| 19601 | instance messages that should be displayed as part of an error log. All |
| 19602 | the log output is prefixed by @samp{&}. |
| 19603 | |
| 19604 | @item |
| 19605 | @cindex list output in @sc{gdb/mi} |
| 19606 | New @sc{gdb/mi} commands should only output @var{lists} containing |
| 19607 | @var{values}. |
| 19608 | |
| 19609 | |
| 19610 | @end itemize |
| 19611 | |
| 19612 | @xref{GDB/MI Stream Records, , @sc{gdb/mi} Stream Records}, for more |
| 19613 | details about the various output records. |
| 19614 | |
| 19615 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19616 | @node GDB/MI Compatibility with CLI |
| 19617 | @section @sc{gdb/mi} Compatibility with CLI |
| 19618 | |
| 19619 | @cindex compatibility, @sc{gdb/mi} and CLI |
| 19620 | @cindex @sc{gdb/mi}, compatibility with CLI |
| 19621 | |
| 19622 | For the developers convenience CLI commands can be entered directly, |
| 19623 | but there may be some unexpected behaviour. For example, commands |
| 19624 | that query the user will behave as if the user replied yes, breakpoint |
| 19625 | command lists are not executed and some CLI commands, such as |
| 19626 | @code{if}, @code{when} and @code{define}, prompt for further input with |
| 19627 | @samp{>}, which is not valid MI output. |
| 19628 | |
| 19629 | This feature may be removed at some stage in the future and it is |
| 19630 | recommended that front ends use the @code{-interpreter-exec} command |
| 19631 | (@pxref{-interpreter-exec}). |
| 19632 | |
| 19633 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19634 | @node GDB/MI Development and Front Ends |
| 19635 | @section @sc{gdb/mi} Development and Front Ends |
| 19636 | @cindex @sc{gdb/mi} development |
| 19637 | |
| 19638 | The application which takes the MI output and presents the state of the |
| 19639 | program being debugged to the user is called a @dfn{front end}. |
| 19640 | |
| 19641 | Although @sc{gdb/mi} is still incomplete, it is currently being used |
| 19642 | by a variety of front ends to @value{GDBN}. This makes it difficult |
| 19643 | to introduce new functionality without breaking existing usage. This |
| 19644 | section tries to minimize the problems by describing how the protocol |
| 19645 | might change. |
| 19646 | |
| 19647 | Some changes in MI need not break a carefully designed front end, and |
| 19648 | for these the MI version will remain unchanged. The following is a |
| 19649 | list of changes that may occur within one level, so front ends should |
| 19650 | parse MI output in a way that can handle them: |
| 19651 | |
| 19652 | @itemize @bullet |
| 19653 | @item |
| 19654 | New MI commands may be added. |
| 19655 | |
| 19656 | @item |
| 19657 | New fields may be added to the output of any MI command. |
| 19658 | |
| 19659 | @item |
| 19660 | The range of values for fields with specified values, e.g., |
| 19661 | @code{in_scope} (@pxref{-var-update}) may be extended. |
| 19662 | |
| 19663 | @c The format of field's content e.g type prefix, may change so parse it |
| 19664 | @c at your own risk. Yes, in general? |
| 19665 | |
| 19666 | @c The order of fields may change? Shouldn't really matter but it might |
| 19667 | @c resolve inconsistencies. |
| 19668 | @end itemize |
| 19669 | |
| 19670 | If the changes are likely to break front ends, the MI version level |
| 19671 | will be increased by one. This will allow the front end to parse the |
| 19672 | output according to the MI version. Apart from mi0, new versions of |
| 19673 | @value{GDBN} will not support old versions of MI and it will be the |
| 19674 | responsibility of the front end to work with the new one. |
| 19675 | |
| 19676 | @c Starting with mi3, add a new command -mi-version that prints the MI |
| 19677 | @c version? |
| 19678 | |
| 19679 | The best way to avoid unexpected changes in MI that might break your front |
| 19680 | end is to make your project known to @value{GDBN} developers and |
| 19681 | follow development on @email{gdb@@sourceware.org} and |
| 19682 | @email{gdb-patches@@sourceware.org}. |
| 19683 | @cindex mailing lists |
| 19684 | |
| 19685 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19686 | @node GDB/MI Output Records |
| 19687 | @section @sc{gdb/mi} Output Records |
| 19688 | |
| 19689 | @menu |
| 19690 | * GDB/MI Result Records:: |
| 19691 | * GDB/MI Stream Records:: |
| 19692 | * GDB/MI Async Records:: |
| 19693 | * GDB/MI Frame Information:: |
| 19694 | @end menu |
| 19695 | |
| 19696 | @node GDB/MI Result Records |
| 19697 | @subsection @sc{gdb/mi} Result Records |
| 19698 | |
| 19699 | @cindex result records in @sc{gdb/mi} |
| 19700 | @cindex @sc{gdb/mi}, result records |
| 19701 | In addition to a number of out-of-band notifications, the response to a |
| 19702 | @sc{gdb/mi} command includes one of the following result indications: |
| 19703 | |
| 19704 | @table @code |
| 19705 | @findex ^done |
| 19706 | @item "^done" [ "," @var{results} ] |
| 19707 | The synchronous operation was successful, @code{@var{results}} are the return |
| 19708 | values. |
| 19709 | |
| 19710 | @item "^running" |
| 19711 | @findex ^running |
| 19712 | @c Is this one correct? Should it be an out-of-band notification? |
| 19713 | The asynchronous operation was successfully started. The target is |
| 19714 | running. |
| 19715 | |
| 19716 | @item "^connected" |
| 19717 | @findex ^connected |
| 19718 | @value{GDBN} has connected to a remote target. |
| 19719 | |
| 19720 | @item "^error" "," @var{c-string} |
| 19721 | @findex ^error |
| 19722 | The operation failed. The @code{@var{c-string}} contains the corresponding |
| 19723 | error message. |
| 19724 | |
| 19725 | @item "^exit" |
| 19726 | @findex ^exit |
| 19727 | @value{GDBN} has terminated. |
| 19728 | |
| 19729 | @end table |
| 19730 | |
| 19731 | @node GDB/MI Stream Records |
| 19732 | @subsection @sc{gdb/mi} Stream Records |
| 19733 | |
| 19734 | @cindex @sc{gdb/mi}, stream records |
| 19735 | @cindex stream records in @sc{gdb/mi} |
| 19736 | @value{GDBN} internally maintains a number of output streams: the console, the |
| 19737 | target, and the log. The output intended for each of these streams is |
| 19738 | funneled through the @sc{gdb/mi} interface using @dfn{stream records}. |
| 19739 | |
| 19740 | Each stream record begins with a unique @dfn{prefix character} which |
| 19741 | identifies its stream (@pxref{GDB/MI Output Syntax, , @sc{gdb/mi} Output |
| 19742 | Syntax}). In addition to the prefix, each stream record contains a |
| 19743 | @code{@var{string-output}}. This is either raw text (with an implicit new |
| 19744 | line) or a quoted C string (which does not contain an implicit newline). |
| 19745 | |
| 19746 | @table @code |
| 19747 | @item "~" @var{string-output} |
| 19748 | The console output stream contains text that should be displayed in the |
| 19749 | CLI console window. It contains the textual responses to CLI commands. |
| 19750 | |
| 19751 | @item "@@" @var{string-output} |
| 19752 | The target output stream contains any textual output from the running |
| 19753 | target. This is only present when GDB's event loop is truly |
| 19754 | asynchronous, which is currently only the case for remote targets. |
| 19755 | |
| 19756 | @item "&" @var{string-output} |
| 19757 | The log stream contains debugging messages being produced by @value{GDBN}'s |
| 19758 | internals. |
| 19759 | @end table |
| 19760 | |
| 19761 | @node GDB/MI Async Records |
| 19762 | @subsection @sc{gdb/mi} Async Records |
| 19763 | |
| 19764 | @cindex async records in @sc{gdb/mi} |
| 19765 | @cindex @sc{gdb/mi}, async records |
| 19766 | @dfn{Async} records are used to notify the @sc{gdb/mi} client of |
| 19767 | additional changes that have occurred. Those changes can either be a |
| 19768 | consequence of @sc{gdb/mi} commands (e.g., a breakpoint modified) or a result of |
| 19769 | target activity (e.g., target stopped). |
| 19770 | |
| 19771 | The following is the list of possible async records: |
| 19772 | |
| 19773 | @table @code |
| 19774 | |
| 19775 | @item *running,thread-id="@var{thread}" |
| 19776 | The target is now running. The @var{thread} field tells which |
| 19777 | specific thread is now running, and can be @samp{all} if all threads |
| 19778 | are running. The frontend should assume that no interaction with a |
| 19779 | running thread is possible after this notification is produced. |
| 19780 | The frontend should not assume that this notification is output |
| 19781 | only once for any command. @value{GDBN} may emit this notification |
| 19782 | several times, either for different threads, because it cannot resume |
| 19783 | all threads together, or even for a single thread, if the thread must |
| 19784 | be stepped though some code before letting it run freely. |
| 19785 | |
| 19786 | @item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}" |
| 19787 | The target has stopped. The @var{reason} field can have one of the |
| 19788 | following values: |
| 19789 | |
| 19790 | @table @code |
| 19791 | @item breakpoint-hit |
| 19792 | A breakpoint was reached. |
| 19793 | @item watchpoint-trigger |
| 19794 | A watchpoint was triggered. |
| 19795 | @item read-watchpoint-trigger |
| 19796 | A read watchpoint was triggered. |
| 19797 | @item access-watchpoint-trigger |
| 19798 | An access watchpoint was triggered. |
| 19799 | @item function-finished |
| 19800 | An -exec-finish or similar CLI command was accomplished. |
| 19801 | @item location-reached |
| 19802 | An -exec-until or similar CLI command was accomplished. |
| 19803 | @item watchpoint-scope |
| 19804 | A watchpoint has gone out of scope. |
| 19805 | @item end-stepping-range |
| 19806 | An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or |
| 19807 | similar CLI command was accomplished. |
| 19808 | @item exited-signalled |
| 19809 | The inferior exited because of a signal. |
| 19810 | @item exited |
| 19811 | The inferior exited. |
| 19812 | @item exited-normally |
| 19813 | The inferior exited normally. |
| 19814 | @item signal-received |
| 19815 | A signal was received by the inferior. |
| 19816 | @end table |
| 19817 | |
| 19818 | The @var{id} field identifies the thread that directly caused the stop |
| 19819 | -- for example by hitting a breakpoint. Depending on whether all-stop |
| 19820 | mode is in effect (@pxref{All-Stop Mode}), @value{GDBN} may either |
| 19821 | stop all threads, or only the thread that directly triggered the stop. |
| 19822 | If all threads are stopped, the @var{stopped} field will have the |
| 19823 | value of @code{"all"}. Otherwise, the value of the @var{stopped} |
| 19824 | field will be a list of thread identifiers. Presently, this list will |
| 19825 | always include a single thread, but frontend should be prepared to see |
| 19826 | several threads in the list. |
| 19827 | |
| 19828 | @item =thread-group-created,id="@var{id}" |
| 19829 | @itemx =thread-group-exited,id="@var{id}" |
| 19830 | A thread thread group either was attached to, or has exited/detached |
| 19831 | from. The @var{id} field contains the @value{GDBN} identifier of the |
| 19832 | thread group. |
| 19833 | |
| 19834 | @item =thread-created,id="@var{id}",group-id="@var{gid}" |
| 19835 | @itemx =thread-exited,id="@var{id}",group-id="@var{gid}" |
| 19836 | A thread either was created, or has exited. The @var{id} field |
| 19837 | contains the @value{GDBN} identifier of the thread. The @var{gid} |
| 19838 | field identifies the thread group this thread belongs to. |
| 19839 | |
| 19840 | @item =thread-selected,id="@var{id}" |
| 19841 | Informs that the selected thread was changed as result of the last |
| 19842 | command. This notification is not emitted as result of @code{-thread-select} |
| 19843 | command but is emitted whenever an MI command that is not documented |
| 19844 | to change the selected thread actually changes it. In particular, |
| 19845 | invoking, directly or indirectly (via user-defined command), the CLI |
| 19846 | @code{thread} command, will generate this notification. |
| 19847 | |
| 19848 | We suggest that in response to this notification, front ends |
| 19849 | highlight the selected thread and cause subsequent commands to apply to |
| 19850 | that thread. |
| 19851 | |
| 19852 | @end table |
| 19853 | |
| 19854 | @node GDB/MI Frame Information |
| 19855 | @subsection @sc{gdb/mi} Frame Information |
| 19856 | |
| 19857 | Response from many MI commands includes an information about stack |
| 19858 | frame. This information is a tuple that may have the following |
| 19859 | fields: |
| 19860 | |
| 19861 | @table @code |
| 19862 | @item level |
| 19863 | The level of the stack frame. The innermost frame has the level of |
| 19864 | zero. This field is always present. |
| 19865 | |
| 19866 | @item func |
| 19867 | The name of the function corresponding to the frame. This field may |
| 19868 | be absent if @value{GDBN} is unable to determine the function name. |
| 19869 | |
| 19870 | @item addr |
| 19871 | The code address for the frame. This field is always present. |
| 19872 | |
| 19873 | @item file |
| 19874 | The name of the source files that correspond to the frame's code |
| 19875 | address. This field may be absent. |
| 19876 | |
| 19877 | @item line |
| 19878 | The source line corresponding to the frames' code address. This field |
| 19879 | may be absent. |
| 19880 | |
| 19881 | @item from |
| 19882 | The name of the binary file (either executable or shared library) the |
| 19883 | corresponds to the frame's code address. This field may be absent. |
| 19884 | |
| 19885 | @end table |
| 19886 | |
| 19887 | |
| 19888 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19889 | @node GDB/MI Simple Examples |
| 19890 | @section Simple Examples of @sc{gdb/mi} Interaction |
| 19891 | @cindex @sc{gdb/mi}, simple examples |
| 19892 | |
| 19893 | This subsection presents several simple examples of interaction using |
| 19894 | the @sc{gdb/mi} interface. In these examples, @samp{->} means that the |
| 19895 | following line is passed to @sc{gdb/mi} as input, while @samp{<-} means |
| 19896 | the output received from @sc{gdb/mi}. |
| 19897 | |
| 19898 | Note the line breaks shown in the examples are here only for |
| 19899 | readability, they don't appear in the real output. |
| 19900 | |
| 19901 | @subheading Setting a Breakpoint |
| 19902 | |
| 19903 | Setting a breakpoint generates synchronous output which contains detailed |
| 19904 | information of the breakpoint. |
| 19905 | |
| 19906 | @smallexample |
| 19907 | -> -break-insert main |
| 19908 | <- ^done,bkpt=@{number="1",type="breakpoint",disp="keep", |
| 19909 | enabled="y",addr="0x08048564",func="main",file="myprog.c", |
| 19910 | fullname="/home/nickrob/myprog.c",line="68",times="0"@} |
| 19911 | <- (gdb) |
| 19912 | @end smallexample |
| 19913 | |
| 19914 | @subheading Program Execution |
| 19915 | |
| 19916 | Program execution generates asynchronous records and MI gives the |
| 19917 | reason that execution stopped. |
| 19918 | |
| 19919 | @smallexample |
| 19920 | -> -exec-run |
| 19921 | <- ^running |
| 19922 | <- (gdb) |
| 19923 | <- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0", |
| 19924 | frame=@{addr="0x08048564",func="main", |
| 19925 | args=[@{name="argc",value="1"@},@{name="argv",value="0xbfc4d4d4"@}], |
| 19926 | file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"@} |
| 19927 | <- (gdb) |
| 19928 | -> -exec-continue |
| 19929 | <- ^running |
| 19930 | <- (gdb) |
| 19931 | <- *stopped,reason="exited-normally" |
| 19932 | <- (gdb) |
| 19933 | @end smallexample |
| 19934 | |
| 19935 | @subheading Quitting @value{GDBN} |
| 19936 | |
| 19937 | Quitting @value{GDBN} just prints the result class @samp{^exit}. |
| 19938 | |
| 19939 | @smallexample |
| 19940 | -> (gdb) |
| 19941 | <- -gdb-exit |
| 19942 | <- ^exit |
| 19943 | @end smallexample |
| 19944 | |
| 19945 | @subheading A Bad Command |
| 19946 | |
| 19947 | Here's what happens if you pass a non-existent command: |
| 19948 | |
| 19949 | @smallexample |
| 19950 | -> -rubbish |
| 19951 | <- ^error,msg="Undefined MI command: rubbish" |
| 19952 | <- (gdb) |
| 19953 | @end smallexample |
| 19954 | |
| 19955 | |
| 19956 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19957 | @node GDB/MI Command Description Format |
| 19958 | @section @sc{gdb/mi} Command Description Format |
| 19959 | |
| 19960 | The remaining sections describe blocks of commands. Each block of |
| 19961 | commands is laid out in a fashion similar to this section. |
| 19962 | |
| 19963 | @subheading Motivation |
| 19964 | |
| 19965 | The motivation for this collection of commands. |
| 19966 | |
| 19967 | @subheading Introduction |
| 19968 | |
| 19969 | A brief introduction to this collection of commands as a whole. |
| 19970 | |
| 19971 | @subheading Commands |
| 19972 | |
| 19973 | For each command in the block, the following is described: |
| 19974 | |
| 19975 | @subsubheading Synopsis |
| 19976 | |
| 19977 | @smallexample |
| 19978 | -command @var{args}@dots{} |
| 19979 | @end smallexample |
| 19980 | |
| 19981 | @subsubheading Result |
| 19982 | |
| 19983 | @subsubheading @value{GDBN} Command |
| 19984 | |
| 19985 | The corresponding @value{GDBN} CLI command(s), if any. |
| 19986 | |
| 19987 | @subsubheading Example |
| 19988 | |
| 19989 | Example(s) formatted for readability. Some of the described commands have |
| 19990 | not been implemented yet and these are labeled N.A.@: (not available). |
| 19991 | |
| 19992 | |
| 19993 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 19994 | @node GDB/MI Breakpoint Commands |
| 19995 | @section @sc{gdb/mi} Breakpoint Commands |
| 19996 | |
| 19997 | @cindex breakpoint commands for @sc{gdb/mi} |
| 19998 | @cindex @sc{gdb/mi}, breakpoint commands |
| 19999 | This section documents @sc{gdb/mi} commands for manipulating |
| 20000 | breakpoints. |
| 20001 | |
| 20002 | @subheading The @code{-break-after} Command |
| 20003 | @findex -break-after |
| 20004 | |
| 20005 | @subsubheading Synopsis |
| 20006 | |
| 20007 | @smallexample |
| 20008 | -break-after @var{number} @var{count} |
| 20009 | @end smallexample |
| 20010 | |
| 20011 | The breakpoint number @var{number} is not in effect until it has been |
| 20012 | hit @var{count} times. To see how this is reflected in the output of |
| 20013 | the @samp{-break-list} command, see the description of the |
| 20014 | @samp{-break-list} command below. |
| 20015 | |
| 20016 | @subsubheading @value{GDBN} Command |
| 20017 | |
| 20018 | The corresponding @value{GDBN} command is @samp{ignore}. |
| 20019 | |
| 20020 | @subsubheading Example |
| 20021 | |
| 20022 | @smallexample |
| 20023 | (gdb) |
| 20024 | -break-insert main |
| 20025 | ^done,bkpt=@{number="1",type="breakpoint",disp="keep", |
| 20026 | enabled="y",addr="0x000100d0",func="main",file="hello.c", |
| 20027 | fullname="/home/foo/hello.c",line="5",times="0"@} |
| 20028 | (gdb) |
| 20029 | -break-after 1 3 |
| 20030 | ~ |
| 20031 | ^done |
| 20032 | (gdb) |
| 20033 | -break-list |
| 20034 | ^done,BreakpointTable=@{nr_rows="1",nr_cols="6", |
| 20035 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20036 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20037 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20038 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20039 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20040 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20041 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20042 | addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", |
| 20043 | line="5",times="0",ignore="3"@}]@} |
| 20044 | (gdb) |
| 20045 | @end smallexample |
| 20046 | |
| 20047 | @ignore |
| 20048 | @subheading The @code{-break-catch} Command |
| 20049 | @findex -break-catch |
| 20050 | |
| 20051 | @subheading The @code{-break-commands} Command |
| 20052 | @findex -break-commands |
| 20053 | @end ignore |
| 20054 | |
| 20055 | |
| 20056 | @subheading The @code{-break-condition} Command |
| 20057 | @findex -break-condition |
| 20058 | |
| 20059 | @subsubheading Synopsis |
| 20060 | |
| 20061 | @smallexample |
| 20062 | -break-condition @var{number} @var{expr} |
| 20063 | @end smallexample |
| 20064 | |
| 20065 | Breakpoint @var{number} will stop the program only if the condition in |
| 20066 | @var{expr} is true. The condition becomes part of the |
| 20067 | @samp{-break-list} output (see the description of the @samp{-break-list} |
| 20068 | command below). |
| 20069 | |
| 20070 | @subsubheading @value{GDBN} Command |
| 20071 | |
| 20072 | The corresponding @value{GDBN} command is @samp{condition}. |
| 20073 | |
| 20074 | @subsubheading Example |
| 20075 | |
| 20076 | @smallexample |
| 20077 | (gdb) |
| 20078 | -break-condition 1 1 |
| 20079 | ^done |
| 20080 | (gdb) |
| 20081 | -break-list |
| 20082 | ^done,BreakpointTable=@{nr_rows="1",nr_cols="6", |
| 20083 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20084 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20085 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20086 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20087 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20088 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20089 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20090 | addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", |
| 20091 | line="5",cond="1",times="0",ignore="3"@}]@} |
| 20092 | (gdb) |
| 20093 | @end smallexample |
| 20094 | |
| 20095 | @subheading The @code{-break-delete} Command |
| 20096 | @findex -break-delete |
| 20097 | |
| 20098 | @subsubheading Synopsis |
| 20099 | |
| 20100 | @smallexample |
| 20101 | -break-delete ( @var{breakpoint} )+ |
| 20102 | @end smallexample |
| 20103 | |
| 20104 | Delete the breakpoint(s) whose number(s) are specified in the argument |
| 20105 | list. This is obviously reflected in the breakpoint list. |
| 20106 | |
| 20107 | @subsubheading @value{GDBN} Command |
| 20108 | |
| 20109 | The corresponding @value{GDBN} command is @samp{delete}. |
| 20110 | |
| 20111 | @subsubheading Example |
| 20112 | |
| 20113 | @smallexample |
| 20114 | (gdb) |
| 20115 | -break-delete 1 |
| 20116 | ^done |
| 20117 | (gdb) |
| 20118 | -break-list |
| 20119 | ^done,BreakpointTable=@{nr_rows="0",nr_cols="6", |
| 20120 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20121 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20122 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20123 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20124 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20125 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20126 | body=[]@} |
| 20127 | (gdb) |
| 20128 | @end smallexample |
| 20129 | |
| 20130 | @subheading The @code{-break-disable} Command |
| 20131 | @findex -break-disable |
| 20132 | |
| 20133 | @subsubheading Synopsis |
| 20134 | |
| 20135 | @smallexample |
| 20136 | -break-disable ( @var{breakpoint} )+ |
| 20137 | @end smallexample |
| 20138 | |
| 20139 | Disable the named @var{breakpoint}(s). The field @samp{enabled} in the |
| 20140 | break list is now set to @samp{n} for the named @var{breakpoint}(s). |
| 20141 | |
| 20142 | @subsubheading @value{GDBN} Command |
| 20143 | |
| 20144 | The corresponding @value{GDBN} command is @samp{disable}. |
| 20145 | |
| 20146 | @subsubheading Example |
| 20147 | |
| 20148 | @smallexample |
| 20149 | (gdb) |
| 20150 | -break-disable 2 |
| 20151 | ^done |
| 20152 | (gdb) |
| 20153 | -break-list |
| 20154 | ^done,BreakpointTable=@{nr_rows="1",nr_cols="6", |
| 20155 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20156 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20157 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20158 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20159 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20160 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20161 | body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="n", |
| 20162 | addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", |
| 20163 | line="5",times="0"@}]@} |
| 20164 | (gdb) |
| 20165 | @end smallexample |
| 20166 | |
| 20167 | @subheading The @code{-break-enable} Command |
| 20168 | @findex -break-enable |
| 20169 | |
| 20170 | @subsubheading Synopsis |
| 20171 | |
| 20172 | @smallexample |
| 20173 | -break-enable ( @var{breakpoint} )+ |
| 20174 | @end smallexample |
| 20175 | |
| 20176 | Enable (previously disabled) @var{breakpoint}(s). |
| 20177 | |
| 20178 | @subsubheading @value{GDBN} Command |
| 20179 | |
| 20180 | The corresponding @value{GDBN} command is @samp{enable}. |
| 20181 | |
| 20182 | @subsubheading Example |
| 20183 | |
| 20184 | @smallexample |
| 20185 | (gdb) |
| 20186 | -break-enable 2 |
| 20187 | ^done |
| 20188 | (gdb) |
| 20189 | -break-list |
| 20190 | ^done,BreakpointTable=@{nr_rows="1",nr_cols="6", |
| 20191 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20192 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20193 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20194 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20195 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20196 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20197 | body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y", |
| 20198 | addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", |
| 20199 | line="5",times="0"@}]@} |
| 20200 | (gdb) |
| 20201 | @end smallexample |
| 20202 | |
| 20203 | @subheading The @code{-break-info} Command |
| 20204 | @findex -break-info |
| 20205 | |
| 20206 | @subsubheading Synopsis |
| 20207 | |
| 20208 | @smallexample |
| 20209 | -break-info @var{breakpoint} |
| 20210 | @end smallexample |
| 20211 | |
| 20212 | @c REDUNDANT??? |
| 20213 | Get information about a single breakpoint. |
| 20214 | |
| 20215 | @subsubheading @value{GDBN} Command |
| 20216 | |
| 20217 | The corresponding @value{GDBN} command is @samp{info break @var{breakpoint}}. |
| 20218 | |
| 20219 | @subsubheading Example |
| 20220 | N.A. |
| 20221 | |
| 20222 | @subheading The @code{-break-insert} Command |
| 20223 | @findex -break-insert |
| 20224 | |
| 20225 | @subsubheading Synopsis |
| 20226 | |
| 20227 | @smallexample |
| 20228 | -break-insert [ -t ] [ -h ] [ -f ] [ -d ] |
| 20229 | [ -c @var{condition} ] [ -i @var{ignore-count} ] |
| 20230 | [ -p @var{thread} ] [ @var{location} ] |
| 20231 | @end smallexample |
| 20232 | |
| 20233 | @noindent |
| 20234 | If specified, @var{location}, can be one of: |
| 20235 | |
| 20236 | @itemize @bullet |
| 20237 | @item function |
| 20238 | @c @item +offset |
| 20239 | @c @item -offset |
| 20240 | @c @item linenum |
| 20241 | @item filename:linenum |
| 20242 | @item filename:function |
| 20243 | @item *address |
| 20244 | @end itemize |
| 20245 | |
| 20246 | The possible optional parameters of this command are: |
| 20247 | |
| 20248 | @table @samp |
| 20249 | @item -t |
| 20250 | Insert a temporary breakpoint. |
| 20251 | @item -h |
| 20252 | Insert a hardware breakpoint. |
| 20253 | @item -c @var{condition} |
| 20254 | Make the breakpoint conditional on @var{condition}. |
| 20255 | @item -i @var{ignore-count} |
| 20256 | Initialize the @var{ignore-count}. |
| 20257 | @item -f |
| 20258 | If @var{location} cannot be parsed (for example if it |
| 20259 | refers to unknown files or functions), create a pending |
| 20260 | breakpoint. Without this flag, @value{GDBN} will report |
| 20261 | an error, and won't create a breakpoint, if @var{location} |
| 20262 | cannot be parsed. |
| 20263 | @item -d |
| 20264 | Create a disabled breakpoint. |
| 20265 | @end table |
| 20266 | |
| 20267 | @subsubheading Result |
| 20268 | |
| 20269 | The result is in the form: |
| 20270 | |
| 20271 | @smallexample |
| 20272 | ^done,bkpt=@{number="@var{number}",type="@var{type}",disp="del"|"keep", |
| 20273 | enabled="y"|"n",addr="@var{hex}",func="@var{funcname}",file="@var{filename}", |
| 20274 | fullname="@var{full_filename}",line="@var{lineno}",[thread="@var{threadno},] |
| 20275 | times="@var{times}"@} |
| 20276 | @end smallexample |
| 20277 | |
| 20278 | @noindent |
| 20279 | where @var{number} is the @value{GDBN} number for this breakpoint, |
| 20280 | @var{funcname} is the name of the function where the breakpoint was |
| 20281 | inserted, @var{filename} is the name of the source file which contains |
| 20282 | this function, @var{lineno} is the source line number within that file |
| 20283 | and @var{times} the number of times that the breakpoint has been hit |
| 20284 | (always 0 for -break-insert but may be greater for -break-info or -break-list |
| 20285 | which use the same output). |
| 20286 | |
| 20287 | Note: this format is open to change. |
| 20288 | @c An out-of-band breakpoint instead of part of the result? |
| 20289 | |
| 20290 | @subsubheading @value{GDBN} Command |
| 20291 | |
| 20292 | The corresponding @value{GDBN} commands are @samp{break}, @samp{tbreak}, |
| 20293 | @samp{hbreak}, @samp{thbreak}, and @samp{rbreak}. |
| 20294 | |
| 20295 | @subsubheading Example |
| 20296 | |
| 20297 | @smallexample |
| 20298 | (gdb) |
| 20299 | -break-insert main |
| 20300 | ^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c", |
| 20301 | fullname="/home/foo/recursive2.c,line="4",times="0"@} |
| 20302 | (gdb) |
| 20303 | -break-insert -t foo |
| 20304 | ^done,bkpt=@{number="2",addr="0x00010774",file="recursive2.c", |
| 20305 | fullname="/home/foo/recursive2.c,line="11",times="0"@} |
| 20306 | (gdb) |
| 20307 | -break-list |
| 20308 | ^done,BreakpointTable=@{nr_rows="2",nr_cols="6", |
| 20309 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20310 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20311 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20312 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20313 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20314 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20315 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20316 | addr="0x0001072c", func="main",file="recursive2.c", |
| 20317 | fullname="/home/foo/recursive2.c,"line="4",times="0"@}, |
| 20318 | bkpt=@{number="2",type="breakpoint",disp="del",enabled="y", |
| 20319 | addr="0x00010774",func="foo",file="recursive2.c", |
| 20320 | fullname="/home/foo/recursive2.c",line="11",times="0"@}]@} |
| 20321 | (gdb) |
| 20322 | -break-insert -r foo.* |
| 20323 | ~int foo(int, int); |
| 20324 | ^done,bkpt=@{number="3",addr="0x00010774",file="recursive2.c, |
| 20325 | "fullname="/home/foo/recursive2.c",line="11",times="0"@} |
| 20326 | (gdb) |
| 20327 | @end smallexample |
| 20328 | |
| 20329 | @subheading The @code{-break-list} Command |
| 20330 | @findex -break-list |
| 20331 | |
| 20332 | @subsubheading Synopsis |
| 20333 | |
| 20334 | @smallexample |
| 20335 | -break-list |
| 20336 | @end smallexample |
| 20337 | |
| 20338 | Displays the list of inserted breakpoints, showing the following fields: |
| 20339 | |
| 20340 | @table @samp |
| 20341 | @item Number |
| 20342 | number of the breakpoint |
| 20343 | @item Type |
| 20344 | type of the breakpoint: @samp{breakpoint} or @samp{watchpoint} |
| 20345 | @item Disposition |
| 20346 | should the breakpoint be deleted or disabled when it is hit: @samp{keep} |
| 20347 | or @samp{nokeep} |
| 20348 | @item Enabled |
| 20349 | is the breakpoint enabled or no: @samp{y} or @samp{n} |
| 20350 | @item Address |
| 20351 | memory location at which the breakpoint is set |
| 20352 | @item What |
| 20353 | logical location of the breakpoint, expressed by function name, file |
| 20354 | name, line number |
| 20355 | @item Times |
| 20356 | number of times the breakpoint has been hit |
| 20357 | @end table |
| 20358 | |
| 20359 | If there are no breakpoints or watchpoints, the @code{BreakpointTable} |
| 20360 | @code{body} field is an empty list. |
| 20361 | |
| 20362 | @subsubheading @value{GDBN} Command |
| 20363 | |
| 20364 | The corresponding @value{GDBN} command is @samp{info break}. |
| 20365 | |
| 20366 | @subsubheading Example |
| 20367 | |
| 20368 | @smallexample |
| 20369 | (gdb) |
| 20370 | -break-list |
| 20371 | ^done,BreakpointTable=@{nr_rows="2",nr_cols="6", |
| 20372 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20373 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20374 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20375 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20376 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20377 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20378 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20379 | addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@}, |
| 20380 | bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y", |
| 20381 | addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c", |
| 20382 | line="13",times="0"@}]@} |
| 20383 | (gdb) |
| 20384 | @end smallexample |
| 20385 | |
| 20386 | Here's an example of the result when there are no breakpoints: |
| 20387 | |
| 20388 | @smallexample |
| 20389 | (gdb) |
| 20390 | -break-list |
| 20391 | ^done,BreakpointTable=@{nr_rows="0",nr_cols="6", |
| 20392 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20393 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20394 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20395 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20396 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20397 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20398 | body=[]@} |
| 20399 | (gdb) |
| 20400 | @end smallexample |
| 20401 | |
| 20402 | @subheading The @code{-break-watch} Command |
| 20403 | @findex -break-watch |
| 20404 | |
| 20405 | @subsubheading Synopsis |
| 20406 | |
| 20407 | @smallexample |
| 20408 | -break-watch [ -a | -r ] |
| 20409 | @end smallexample |
| 20410 | |
| 20411 | Create a watchpoint. With the @samp{-a} option it will create an |
| 20412 | @dfn{access} watchpoint, i.e., a watchpoint that triggers either on a |
| 20413 | read from or on a write to the memory location. With the @samp{-r} |
| 20414 | option, the watchpoint created is a @dfn{read} watchpoint, i.e., it will |
| 20415 | trigger only when the memory location is accessed for reading. Without |
| 20416 | either of the options, the watchpoint created is a regular watchpoint, |
| 20417 | i.e., it will trigger when the memory location is accessed for writing. |
| 20418 | @xref{Set Watchpoints, , Setting Watchpoints}. |
| 20419 | |
| 20420 | Note that @samp{-break-list} will report a single list of watchpoints and |
| 20421 | breakpoints inserted. |
| 20422 | |
| 20423 | @subsubheading @value{GDBN} Command |
| 20424 | |
| 20425 | The corresponding @value{GDBN} commands are @samp{watch}, @samp{awatch}, and |
| 20426 | @samp{rwatch}. |
| 20427 | |
| 20428 | @subsubheading Example |
| 20429 | |
| 20430 | Setting a watchpoint on a variable in the @code{main} function: |
| 20431 | |
| 20432 | @smallexample |
| 20433 | (gdb) |
| 20434 | -break-watch x |
| 20435 | ^done,wpt=@{number="2",exp="x"@} |
| 20436 | (gdb) |
| 20437 | -exec-continue |
| 20438 | ^running |
| 20439 | (gdb) |
| 20440 | *stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="x"@}, |
| 20441 | value=@{old="-268439212",new="55"@}, |
| 20442 | frame=@{func="main",args=[],file="recursive2.c", |
| 20443 | fullname="/home/foo/bar/recursive2.c",line="5"@} |
| 20444 | (gdb) |
| 20445 | @end smallexample |
| 20446 | |
| 20447 | Setting a watchpoint on a variable local to a function. @value{GDBN} will stop |
| 20448 | the program execution twice: first for the variable changing value, then |
| 20449 | for the watchpoint going out of scope. |
| 20450 | |
| 20451 | @smallexample |
| 20452 | (gdb) |
| 20453 | -break-watch C |
| 20454 | ^done,wpt=@{number="5",exp="C"@} |
| 20455 | (gdb) |
| 20456 | -exec-continue |
| 20457 | ^running |
| 20458 | (gdb) |
| 20459 | *stopped,reason="watchpoint-trigger", |
| 20460 | wpt=@{number="5",exp="C"@},value=@{old="-276895068",new="3"@}, |
| 20461 | frame=@{func="callee4",args=[], |
| 20462 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20463 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@} |
| 20464 | (gdb) |
| 20465 | -exec-continue |
| 20466 | ^running |
| 20467 | (gdb) |
| 20468 | *stopped,reason="watchpoint-scope",wpnum="5", |
| 20469 | frame=@{func="callee3",args=[@{name="strarg", |
| 20470 | value="0x11940 \"A string argument.\""@}], |
| 20471 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20472 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@} |
| 20473 | (gdb) |
| 20474 | @end smallexample |
| 20475 | |
| 20476 | Listing breakpoints and watchpoints, at different points in the program |
| 20477 | execution. Note that once the watchpoint goes out of scope, it is |
| 20478 | deleted. |
| 20479 | |
| 20480 | @smallexample |
| 20481 | (gdb) |
| 20482 | -break-watch C |
| 20483 | ^done,wpt=@{number="2",exp="C"@} |
| 20484 | (gdb) |
| 20485 | -break-list |
| 20486 | ^done,BreakpointTable=@{nr_rows="2",nr_cols="6", |
| 20487 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20488 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20489 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20490 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20491 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20492 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20493 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20494 | addr="0x00010734",func="callee4", |
| 20495 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20496 | fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",times="1"@}, |
| 20497 | bkpt=@{number="2",type="watchpoint",disp="keep", |
| 20498 | enabled="y",addr="",what="C",times="0"@}]@} |
| 20499 | (gdb) |
| 20500 | -exec-continue |
| 20501 | ^running |
| 20502 | (gdb) |
| 20503 | *stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="C"@}, |
| 20504 | value=@{old="-276895068",new="3"@}, |
| 20505 | frame=@{func="callee4",args=[], |
| 20506 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20507 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@} |
| 20508 | (gdb) |
| 20509 | -break-list |
| 20510 | ^done,BreakpointTable=@{nr_rows="2",nr_cols="6", |
| 20511 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20512 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20513 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20514 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20515 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20516 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20517 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20518 | addr="0x00010734",func="callee4", |
| 20519 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20520 | fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"@}, |
| 20521 | bkpt=@{number="2",type="watchpoint",disp="keep", |
| 20522 | enabled="y",addr="",what="C",times="-5"@}]@} |
| 20523 | (gdb) |
| 20524 | -exec-continue |
| 20525 | ^running |
| 20526 | ^done,reason="watchpoint-scope",wpnum="2", |
| 20527 | frame=@{func="callee3",args=[@{name="strarg", |
| 20528 | value="0x11940 \"A string argument.\""@}], |
| 20529 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20530 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@} |
| 20531 | (gdb) |
| 20532 | -break-list |
| 20533 | ^done,BreakpointTable=@{nr_rows="1",nr_cols="6", |
| 20534 | hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@}, |
| 20535 | @{width="14",alignment="-1",col_name="type",colhdr="Type"@}, |
| 20536 | @{width="4",alignment="-1",col_name="disp",colhdr="Disp"@}, |
| 20537 | @{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@}, |
| 20538 | @{width="10",alignment="-1",col_name="addr",colhdr="Address"@}, |
| 20539 | @{width="40",alignment="2",col_name="what",colhdr="What"@}], |
| 20540 | body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 20541 | addr="0x00010734",func="callee4", |
| 20542 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 20543 | fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8", |
| 20544 | times="1"@}]@} |
| 20545 | (gdb) |
| 20546 | @end smallexample |
| 20547 | |
| 20548 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 20549 | @node GDB/MI Program Context |
| 20550 | @section @sc{gdb/mi} Program Context |
| 20551 | |
| 20552 | @subheading The @code{-exec-arguments} Command |
| 20553 | @findex -exec-arguments |
| 20554 | |
| 20555 | |
| 20556 | @subsubheading Synopsis |
| 20557 | |
| 20558 | @smallexample |
| 20559 | -exec-arguments @var{args} |
| 20560 | @end smallexample |
| 20561 | |
| 20562 | Set the inferior program arguments, to be used in the next |
| 20563 | @samp{-exec-run}. |
| 20564 | |
| 20565 | @subsubheading @value{GDBN} Command |
| 20566 | |
| 20567 | The corresponding @value{GDBN} command is @samp{set args}. |
| 20568 | |
| 20569 | @subsubheading Example |
| 20570 | |
| 20571 | @smallexample |
| 20572 | (gdb) |
| 20573 | -exec-arguments -v word |
| 20574 | ^done |
| 20575 | (gdb) |
| 20576 | @end smallexample |
| 20577 | |
| 20578 | |
| 20579 | @subheading The @code{-exec-show-arguments} Command |
| 20580 | @findex -exec-show-arguments |
| 20581 | |
| 20582 | @subsubheading Synopsis |
| 20583 | |
| 20584 | @smallexample |
| 20585 | -exec-show-arguments |
| 20586 | @end smallexample |
| 20587 | |
| 20588 | Print the arguments of the program. |
| 20589 | |
| 20590 | @subsubheading @value{GDBN} Command |
| 20591 | |
| 20592 | The corresponding @value{GDBN} command is @samp{show args}. |
| 20593 | |
| 20594 | @subsubheading Example |
| 20595 | N.A. |
| 20596 | |
| 20597 | |
| 20598 | @subheading The @code{-environment-cd} Command |
| 20599 | @findex -environment-cd |
| 20600 | |
| 20601 | @subsubheading Synopsis |
| 20602 | |
| 20603 | @smallexample |
| 20604 | -environment-cd @var{pathdir} |
| 20605 | @end smallexample |
| 20606 | |
| 20607 | Set @value{GDBN}'s working directory. |
| 20608 | |
| 20609 | @subsubheading @value{GDBN} Command |
| 20610 | |
| 20611 | The corresponding @value{GDBN} command is @samp{cd}. |
| 20612 | |
| 20613 | @subsubheading Example |
| 20614 | |
| 20615 | @smallexample |
| 20616 | (gdb) |
| 20617 | -environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb |
| 20618 | ^done |
| 20619 | (gdb) |
| 20620 | @end smallexample |
| 20621 | |
| 20622 | |
| 20623 | @subheading The @code{-environment-directory} Command |
| 20624 | @findex -environment-directory |
| 20625 | |
| 20626 | @subsubheading Synopsis |
| 20627 | |
| 20628 | @smallexample |
| 20629 | -environment-directory [ -r ] [ @var{pathdir} ]+ |
| 20630 | @end smallexample |
| 20631 | |
| 20632 | Add directories @var{pathdir} to beginning of search path for source files. |
| 20633 | If the @samp{-r} option is used, the search path is reset to the default |
| 20634 | search path. If directories @var{pathdir} are supplied in addition to the |
| 20635 | @samp{-r} option, the search path is first reset and then addition |
| 20636 | occurs as normal. |
| 20637 | Multiple directories may be specified, separated by blanks. Specifying |
| 20638 | multiple directories in a single command |
| 20639 | results in the directories added to the beginning of the |
| 20640 | search path in the same order they were presented in the command. |
| 20641 | If blanks are needed as |
| 20642 | part of a directory name, double-quotes should be used around |
| 20643 | the name. In the command output, the path will show up separated |
| 20644 | by the system directory-separator character. The directory-separator |
| 20645 | character must not be used |
| 20646 | in any directory name. |
| 20647 | If no directories are specified, the current search path is displayed. |
| 20648 | |
| 20649 | @subsubheading @value{GDBN} Command |
| 20650 | |
| 20651 | The corresponding @value{GDBN} command is @samp{dir}. |
| 20652 | |
| 20653 | @subsubheading Example |
| 20654 | |
| 20655 | @smallexample |
| 20656 | (gdb) |
| 20657 | -environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb |
| 20658 | ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd" |
| 20659 | (gdb) |
| 20660 | -environment-directory "" |
| 20661 | ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd" |
| 20662 | (gdb) |
| 20663 | -environment-directory -r /home/jjohnstn/src/gdb /usr/src |
| 20664 | ^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd" |
| 20665 | (gdb) |
| 20666 | -environment-directory -r |
| 20667 | ^done,source-path="$cdir:$cwd" |
| 20668 | (gdb) |
| 20669 | @end smallexample |
| 20670 | |
| 20671 | |
| 20672 | @subheading The @code{-environment-path} Command |
| 20673 | @findex -environment-path |
| 20674 | |
| 20675 | @subsubheading Synopsis |
| 20676 | |
| 20677 | @smallexample |
| 20678 | -environment-path [ -r ] [ @var{pathdir} ]+ |
| 20679 | @end smallexample |
| 20680 | |
| 20681 | Add directories @var{pathdir} to beginning of search path for object files. |
| 20682 | If the @samp{-r} option is used, the search path is reset to the original |
| 20683 | search path that existed at gdb start-up. If directories @var{pathdir} are |
| 20684 | supplied in addition to the |
| 20685 | @samp{-r} option, the search path is first reset and then addition |
| 20686 | occurs as normal. |
| 20687 | Multiple directories may be specified, separated by blanks. Specifying |
| 20688 | multiple directories in a single command |
| 20689 | results in the directories added to the beginning of the |
| 20690 | search path in the same order they were presented in the command. |
| 20691 | If blanks are needed as |
| 20692 | part of a directory name, double-quotes should be used around |
| 20693 | the name. In the command output, the path will show up separated |
| 20694 | by the system directory-separator character. The directory-separator |
| 20695 | character must not be used |
| 20696 | in any directory name. |
| 20697 | If no directories are specified, the current path is displayed. |
| 20698 | |
| 20699 | |
| 20700 | @subsubheading @value{GDBN} Command |
| 20701 | |
| 20702 | The corresponding @value{GDBN} command is @samp{path}. |
| 20703 | |
| 20704 | @subsubheading Example |
| 20705 | |
| 20706 | @smallexample |
| 20707 | (gdb) |
| 20708 | -environment-path |
| 20709 | ^done,path="/usr/bin" |
| 20710 | (gdb) |
| 20711 | -environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin |
| 20712 | ^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin" |
| 20713 | (gdb) |
| 20714 | -environment-path -r /usr/local/bin |
| 20715 | ^done,path="/usr/local/bin:/usr/bin" |
| 20716 | (gdb) |
| 20717 | @end smallexample |
| 20718 | |
| 20719 | |
| 20720 | @subheading The @code{-environment-pwd} Command |
| 20721 | @findex -environment-pwd |
| 20722 | |
| 20723 | @subsubheading Synopsis |
| 20724 | |
| 20725 | @smallexample |
| 20726 | -environment-pwd |
| 20727 | @end smallexample |
| 20728 | |
| 20729 | Show the current working directory. |
| 20730 | |
| 20731 | @subsubheading @value{GDBN} Command |
| 20732 | |
| 20733 | The corresponding @value{GDBN} command is @samp{pwd}. |
| 20734 | |
| 20735 | @subsubheading Example |
| 20736 | |
| 20737 | @smallexample |
| 20738 | (gdb) |
| 20739 | -environment-pwd |
| 20740 | ^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb" |
| 20741 | (gdb) |
| 20742 | @end smallexample |
| 20743 | |
| 20744 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 20745 | @node GDB/MI Thread Commands |
| 20746 | @section @sc{gdb/mi} Thread Commands |
| 20747 | |
| 20748 | |
| 20749 | @subheading The @code{-thread-info} Command |
| 20750 | @findex -thread-info |
| 20751 | |
| 20752 | @subsubheading Synopsis |
| 20753 | |
| 20754 | @smallexample |
| 20755 | -thread-info [ @var{thread-id} ] |
| 20756 | @end smallexample |
| 20757 | |
| 20758 | Reports information about either a specific thread, if |
| 20759 | the @var{thread-id} parameter is present, or about all |
| 20760 | threads. When printing information about all threads, |
| 20761 | also reports the current thread. |
| 20762 | |
| 20763 | @subsubheading @value{GDBN} Command |
| 20764 | |
| 20765 | The @samp{info thread} command prints the same information |
| 20766 | about all threads. |
| 20767 | |
| 20768 | @subsubheading Example |
| 20769 | |
| 20770 | @smallexample |
| 20771 | -thread-info |
| 20772 | ^done,threads=[ |
| 20773 | @{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)", |
| 20774 | frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]@},state="running"@}, |
| 20775 | @{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)", |
| 20776 | frame=@{level="0",addr="0x0804891f",func="foo",args=[@{name="i",value="10"@}], |
| 20777 | file="/tmp/a.c",fullname="/tmp/a.c",line="158"@},state="running"@}], |
| 20778 | current-thread-id="1" |
| 20779 | (gdb) |
| 20780 | @end smallexample |
| 20781 | |
| 20782 | The @samp{state} field may have the following values: |
| 20783 | |
| 20784 | @table @code |
| 20785 | @item stopped |
| 20786 | The thread is stopped. Frame information is available for stopped |
| 20787 | threads. |
| 20788 | |
| 20789 | @item running |
| 20790 | The thread is running. There's no frame information for running |
| 20791 | threads. |
| 20792 | |
| 20793 | @end table |
| 20794 | |
| 20795 | @subheading The @code{-thread-list-ids} Command |
| 20796 | @findex -thread-list-ids |
| 20797 | |
| 20798 | @subsubheading Synopsis |
| 20799 | |
| 20800 | @smallexample |
| 20801 | -thread-list-ids |
| 20802 | @end smallexample |
| 20803 | |
| 20804 | Produces a list of the currently known @value{GDBN} thread ids. At the |
| 20805 | end of the list it also prints the total number of such threads. |
| 20806 | |
| 20807 | This command is retained for historical reasons, the |
| 20808 | @code{-thread-info} command should be used instead. |
| 20809 | |
| 20810 | @subsubheading @value{GDBN} Command |
| 20811 | |
| 20812 | Part of @samp{info threads} supplies the same information. |
| 20813 | |
| 20814 | @subsubheading Example |
| 20815 | |
| 20816 | @smallexample |
| 20817 | (gdb) |
| 20818 | -thread-list-ids |
| 20819 | ^done,thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@}, |
| 20820 | current-thread-id="1",number-of-threads="3" |
| 20821 | (gdb) |
| 20822 | @end smallexample |
| 20823 | |
| 20824 | |
| 20825 | @subheading The @code{-thread-select} Command |
| 20826 | @findex -thread-select |
| 20827 | |
| 20828 | @subsubheading Synopsis |
| 20829 | |
| 20830 | @smallexample |
| 20831 | -thread-select @var{threadnum} |
| 20832 | @end smallexample |
| 20833 | |
| 20834 | Make @var{threadnum} the current thread. It prints the number of the new |
| 20835 | current thread, and the topmost frame for that thread. |
| 20836 | |
| 20837 | This command is deprecated in favor of explicitly using the |
| 20838 | @samp{--thread} option to each command. |
| 20839 | |
| 20840 | @subsubheading @value{GDBN} Command |
| 20841 | |
| 20842 | The corresponding @value{GDBN} command is @samp{thread}. |
| 20843 | |
| 20844 | @subsubheading Example |
| 20845 | |
| 20846 | @smallexample |
| 20847 | (gdb) |
| 20848 | -exec-next |
| 20849 | ^running |
| 20850 | (gdb) |
| 20851 | *stopped,reason="end-stepping-range",thread-id="2",line="187", |
| 20852 | file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c" |
| 20853 | (gdb) |
| 20854 | -thread-list-ids |
| 20855 | ^done, |
| 20856 | thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@}, |
| 20857 | number-of-threads="3" |
| 20858 | (gdb) |
| 20859 | -thread-select 3 |
| 20860 | ^done,new-thread-id="3", |
| 20861 | frame=@{level="0",func="vprintf", |
| 20862 | args=[@{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""@}, |
| 20863 | @{name="arg",value="0x2"@}],file="vprintf.c",line="31"@} |
| 20864 | (gdb) |
| 20865 | @end smallexample |
| 20866 | |
| 20867 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 20868 | @node GDB/MI Program Execution |
| 20869 | @section @sc{gdb/mi} Program Execution |
| 20870 | |
| 20871 | These are the asynchronous commands which generate the out-of-band |
| 20872 | record @samp{*stopped}. Currently @value{GDBN} only really executes |
| 20873 | asynchronously with remote targets and this interaction is mimicked in |
| 20874 | other cases. |
| 20875 | |
| 20876 | @subheading The @code{-exec-continue} Command |
| 20877 | @findex -exec-continue |
| 20878 | |
| 20879 | @subsubheading Synopsis |
| 20880 | |
| 20881 | @smallexample |
| 20882 | -exec-continue [--all|--thread-group N] |
| 20883 | @end smallexample |
| 20884 | |
| 20885 | Resumes the execution of the inferior program until a breakpoint is |
| 20886 | encountered, or until the inferior exits. In all-stop mode |
| 20887 | (@pxref{All-Stop Mode}), may resume only one thread, or all threads, |
| 20888 | depending on the value of the @samp{scheduler-locking} variable. In |
| 20889 | non-stop mode (@pxref{Non-Stop Mode}), if the @samp{--all} is not |
| 20890 | specified, only the thread specified with the @samp{--thread} option |
| 20891 | (or current thread, if no @samp{--thread} is provided) is resumed. If |
| 20892 | @samp{--all} is specified, all threads will be resumed. The |
| 20893 | @samp{--all} option is ignored in all-stop mode. If the |
| 20894 | @samp{--thread-group} options is specified, then all threads in that |
| 20895 | thread group are resumed. |
| 20896 | |
| 20897 | @subsubheading @value{GDBN} Command |
| 20898 | |
| 20899 | The corresponding @value{GDBN} corresponding is @samp{continue}. |
| 20900 | |
| 20901 | @subsubheading Example |
| 20902 | |
| 20903 | @smallexample |
| 20904 | -exec-continue |
| 20905 | ^running |
| 20906 | (gdb) |
| 20907 | @@Hello world |
| 20908 | *stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame=@{ |
| 20909 | func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c", |
| 20910 | line="13"@} |
| 20911 | (gdb) |
| 20912 | @end smallexample |
| 20913 | |
| 20914 | |
| 20915 | @subheading The @code{-exec-finish} Command |
| 20916 | @findex -exec-finish |
| 20917 | |
| 20918 | @subsubheading Synopsis |
| 20919 | |
| 20920 | @smallexample |
| 20921 | -exec-finish |
| 20922 | @end smallexample |
| 20923 | |
| 20924 | Resumes the execution of the inferior program until the current |
| 20925 | function is exited. Displays the results returned by the function. |
| 20926 | |
| 20927 | @subsubheading @value{GDBN} Command |
| 20928 | |
| 20929 | The corresponding @value{GDBN} command is @samp{finish}. |
| 20930 | |
| 20931 | @subsubheading Example |
| 20932 | |
| 20933 | Function returning @code{void}. |
| 20934 | |
| 20935 | @smallexample |
| 20936 | -exec-finish |
| 20937 | ^running |
| 20938 | (gdb) |
| 20939 | @@hello from foo |
| 20940 | *stopped,reason="function-finished",frame=@{func="main",args=[], |
| 20941 | file="hello.c",fullname="/home/foo/bar/hello.c",line="7"@} |
| 20942 | (gdb) |
| 20943 | @end smallexample |
| 20944 | |
| 20945 | Function returning other than @code{void}. The name of the internal |
| 20946 | @value{GDBN} variable storing the result is printed, together with the |
| 20947 | value itself. |
| 20948 | |
| 20949 | @smallexample |
| 20950 | -exec-finish |
| 20951 | ^running |
| 20952 | (gdb) |
| 20953 | *stopped,reason="function-finished",frame=@{addr="0x000107b0",func="foo", |
| 20954 | args=[@{name="a",value="1"],@{name="b",value="9"@}@}, |
| 20955 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 20956 | gdb-result-var="$1",return-value="0" |
| 20957 | (gdb) |
| 20958 | @end smallexample |
| 20959 | |
| 20960 | |
| 20961 | @subheading The @code{-exec-interrupt} Command |
| 20962 | @findex -exec-interrupt |
| 20963 | |
| 20964 | @subsubheading Synopsis |
| 20965 | |
| 20966 | @smallexample |
| 20967 | -exec-interrupt [--all|--thread-group N] |
| 20968 | @end smallexample |
| 20969 | |
| 20970 | Interrupts the background execution of the target. Note how the token |
| 20971 | associated with the stop message is the one for the execution command |
| 20972 | that has been interrupted. The token for the interrupt itself only |
| 20973 | appears in the @samp{^done} output. If the user is trying to |
| 20974 | interrupt a non-running program, an error message will be printed. |
| 20975 | |
| 20976 | Note that when asynchronous execution is enabled, this command is |
| 20977 | asynchronous just like other execution commands. That is, first the |
| 20978 | @samp{^done} response will be printed, and the target stop will be |
| 20979 | reported after that using the @samp{*stopped} notification. |
| 20980 | |
| 20981 | In non-stop mode, only the context thread is interrupted by default. |
| 20982 | All threads will be interrupted if the @samp{--all} option is |
| 20983 | specified. If the @samp{--thread-group} option is specified, all |
| 20984 | threads in that group will be interrupted. |
| 20985 | |
| 20986 | @subsubheading @value{GDBN} Command |
| 20987 | |
| 20988 | The corresponding @value{GDBN} command is @samp{interrupt}. |
| 20989 | |
| 20990 | @subsubheading Example |
| 20991 | |
| 20992 | @smallexample |
| 20993 | (gdb) |
| 20994 | 111-exec-continue |
| 20995 | 111^running |
| 20996 | |
| 20997 | (gdb) |
| 20998 | 222-exec-interrupt |
| 20999 | 222^done |
| 21000 | (gdb) |
| 21001 | 111*stopped,signal-name="SIGINT",signal-meaning="Interrupt", |
| 21002 | frame=@{addr="0x00010140",func="foo",args=[],file="try.c", |
| 21003 | fullname="/home/foo/bar/try.c",line="13"@} |
| 21004 | (gdb) |
| 21005 | |
| 21006 | (gdb) |
| 21007 | -exec-interrupt |
| 21008 | ^error,msg="mi_cmd_exec_interrupt: Inferior not executing." |
| 21009 | (gdb) |
| 21010 | @end smallexample |
| 21011 | |
| 21012 | |
| 21013 | @subheading The @code{-exec-next} Command |
| 21014 | @findex -exec-next |
| 21015 | |
| 21016 | @subsubheading Synopsis |
| 21017 | |
| 21018 | @smallexample |
| 21019 | -exec-next |
| 21020 | @end smallexample |
| 21021 | |
| 21022 | Resumes execution of the inferior program, stopping when the beginning |
| 21023 | of the next source line is reached. |
| 21024 | |
| 21025 | @subsubheading @value{GDBN} Command |
| 21026 | |
| 21027 | The corresponding @value{GDBN} command is @samp{next}. |
| 21028 | |
| 21029 | @subsubheading Example |
| 21030 | |
| 21031 | @smallexample |
| 21032 | -exec-next |
| 21033 | ^running |
| 21034 | (gdb) |
| 21035 | *stopped,reason="end-stepping-range",line="8",file="hello.c" |
| 21036 | (gdb) |
| 21037 | @end smallexample |
| 21038 | |
| 21039 | |
| 21040 | @subheading The @code{-exec-next-instruction} Command |
| 21041 | @findex -exec-next-instruction |
| 21042 | |
| 21043 | @subsubheading Synopsis |
| 21044 | |
| 21045 | @smallexample |
| 21046 | -exec-next-instruction |
| 21047 | @end smallexample |
| 21048 | |
| 21049 | Executes one machine instruction. If the instruction is a function |
| 21050 | call, continues until the function returns. If the program stops at an |
| 21051 | instruction in the middle of a source line, the address will be |
| 21052 | printed as well. |
| 21053 | |
| 21054 | @subsubheading @value{GDBN} Command |
| 21055 | |
| 21056 | The corresponding @value{GDBN} command is @samp{nexti}. |
| 21057 | |
| 21058 | @subsubheading Example |
| 21059 | |
| 21060 | @smallexample |
| 21061 | (gdb) |
| 21062 | -exec-next-instruction |
| 21063 | ^running |
| 21064 | |
| 21065 | (gdb) |
| 21066 | *stopped,reason="end-stepping-range", |
| 21067 | addr="0x000100d4",line="5",file="hello.c" |
| 21068 | (gdb) |
| 21069 | @end smallexample |
| 21070 | |
| 21071 | |
| 21072 | @subheading The @code{-exec-return} Command |
| 21073 | @findex -exec-return |
| 21074 | |
| 21075 | @subsubheading Synopsis |
| 21076 | |
| 21077 | @smallexample |
| 21078 | -exec-return |
| 21079 | @end smallexample |
| 21080 | |
| 21081 | Makes current function return immediately. Doesn't execute the inferior. |
| 21082 | Displays the new current frame. |
| 21083 | |
| 21084 | @subsubheading @value{GDBN} Command |
| 21085 | |
| 21086 | The corresponding @value{GDBN} command is @samp{return}. |
| 21087 | |
| 21088 | @subsubheading Example |
| 21089 | |
| 21090 | @smallexample |
| 21091 | (gdb) |
| 21092 | 200-break-insert callee4 |
| 21093 | 200^done,bkpt=@{number="1",addr="0x00010734", |
| 21094 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"@} |
| 21095 | (gdb) |
| 21096 | 000-exec-run |
| 21097 | 000^running |
| 21098 | (gdb) |
| 21099 | 000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1", |
| 21100 | frame=@{func="callee4",args=[], |
| 21101 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21102 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@} |
| 21103 | (gdb) |
| 21104 | 205-break-delete |
| 21105 | 205^done |
| 21106 | (gdb) |
| 21107 | 111-exec-return |
| 21108 | 111^done,frame=@{level="0",func="callee3", |
| 21109 | args=[@{name="strarg", |
| 21110 | value="0x11940 \"A string argument.\""@}], |
| 21111 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21112 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@} |
| 21113 | (gdb) |
| 21114 | @end smallexample |
| 21115 | |
| 21116 | |
| 21117 | @subheading The @code{-exec-run} Command |
| 21118 | @findex -exec-run |
| 21119 | |
| 21120 | @subsubheading Synopsis |
| 21121 | |
| 21122 | @smallexample |
| 21123 | -exec-run |
| 21124 | @end smallexample |
| 21125 | |
| 21126 | Starts execution of the inferior from the beginning. The inferior |
| 21127 | executes until either a breakpoint is encountered or the program |
| 21128 | exits. In the latter case the output will include an exit code, if |
| 21129 | the program has exited exceptionally. |
| 21130 | |
| 21131 | @subsubheading @value{GDBN} Command |
| 21132 | |
| 21133 | The corresponding @value{GDBN} command is @samp{run}. |
| 21134 | |
| 21135 | @subsubheading Examples |
| 21136 | |
| 21137 | @smallexample |
| 21138 | (gdb) |
| 21139 | -break-insert main |
| 21140 | ^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@} |
| 21141 | (gdb) |
| 21142 | -exec-run |
| 21143 | ^running |
| 21144 | (gdb) |
| 21145 | *stopped,reason="breakpoint-hit",disp="keep",bkptno="1", |
| 21146 | frame=@{func="main",args=[],file="recursive2.c", |
| 21147 | fullname="/home/foo/bar/recursive2.c",line="4"@} |
| 21148 | (gdb) |
| 21149 | @end smallexample |
| 21150 | |
| 21151 | @noindent |
| 21152 | Program exited normally: |
| 21153 | |
| 21154 | @smallexample |
| 21155 | (gdb) |
| 21156 | -exec-run |
| 21157 | ^running |
| 21158 | (gdb) |
| 21159 | x = 55 |
| 21160 | *stopped,reason="exited-normally" |
| 21161 | (gdb) |
| 21162 | @end smallexample |
| 21163 | |
| 21164 | @noindent |
| 21165 | Program exited exceptionally: |
| 21166 | |
| 21167 | @smallexample |
| 21168 | (gdb) |
| 21169 | -exec-run |
| 21170 | ^running |
| 21171 | (gdb) |
| 21172 | x = 55 |
| 21173 | *stopped,reason="exited",exit-code="01" |
| 21174 | (gdb) |
| 21175 | @end smallexample |
| 21176 | |
| 21177 | Another way the program can terminate is if it receives a signal such as |
| 21178 | @code{SIGINT}. In this case, @sc{gdb/mi} displays this: |
| 21179 | |
| 21180 | @smallexample |
| 21181 | (gdb) |
| 21182 | *stopped,reason="exited-signalled",signal-name="SIGINT", |
| 21183 | signal-meaning="Interrupt" |
| 21184 | @end smallexample |
| 21185 | |
| 21186 | |
| 21187 | @c @subheading -exec-signal |
| 21188 | |
| 21189 | |
| 21190 | @subheading The @code{-exec-step} Command |
| 21191 | @findex -exec-step |
| 21192 | |
| 21193 | @subsubheading Synopsis |
| 21194 | |
| 21195 | @smallexample |
| 21196 | -exec-step |
| 21197 | @end smallexample |
| 21198 | |
| 21199 | Resumes execution of the inferior program, stopping when the beginning |
| 21200 | of the next source line is reached, if the next source line is not a |
| 21201 | function call. If it is, stop at the first instruction of the called |
| 21202 | function. |
| 21203 | |
| 21204 | @subsubheading @value{GDBN} Command |
| 21205 | |
| 21206 | The corresponding @value{GDBN} command is @samp{step}. |
| 21207 | |
| 21208 | @subsubheading Example |
| 21209 | |
| 21210 | Stepping into a function: |
| 21211 | |
| 21212 | @smallexample |
| 21213 | -exec-step |
| 21214 | ^running |
| 21215 | (gdb) |
| 21216 | *stopped,reason="end-stepping-range", |
| 21217 | frame=@{func="foo",args=[@{name="a",value="10"@}, |
| 21218 | @{name="b",value="0"@}],file="recursive2.c", |
| 21219 | fullname="/home/foo/bar/recursive2.c",line="11"@} |
| 21220 | (gdb) |
| 21221 | @end smallexample |
| 21222 | |
| 21223 | Regular stepping: |
| 21224 | |
| 21225 | @smallexample |
| 21226 | -exec-step |
| 21227 | ^running |
| 21228 | (gdb) |
| 21229 | *stopped,reason="end-stepping-range",line="14",file="recursive2.c" |
| 21230 | (gdb) |
| 21231 | @end smallexample |
| 21232 | |
| 21233 | |
| 21234 | @subheading The @code{-exec-step-instruction} Command |
| 21235 | @findex -exec-step-instruction |
| 21236 | |
| 21237 | @subsubheading Synopsis |
| 21238 | |
| 21239 | @smallexample |
| 21240 | -exec-step-instruction |
| 21241 | @end smallexample |
| 21242 | |
| 21243 | Resumes the inferior which executes one machine instruction. The |
| 21244 | output, once @value{GDBN} has stopped, will vary depending on whether |
| 21245 | we have stopped in the middle of a source line or not. In the former |
| 21246 | case, the address at which the program stopped will be printed as |
| 21247 | well. |
| 21248 | |
| 21249 | @subsubheading @value{GDBN} Command |
| 21250 | |
| 21251 | The corresponding @value{GDBN} command is @samp{stepi}. |
| 21252 | |
| 21253 | @subsubheading Example |
| 21254 | |
| 21255 | @smallexample |
| 21256 | (gdb) |
| 21257 | -exec-step-instruction |
| 21258 | ^running |
| 21259 | |
| 21260 | (gdb) |
| 21261 | *stopped,reason="end-stepping-range", |
| 21262 | frame=@{func="foo",args=[],file="try.c", |
| 21263 | fullname="/home/foo/bar/try.c",line="10"@} |
| 21264 | (gdb) |
| 21265 | -exec-step-instruction |
| 21266 | ^running |
| 21267 | |
| 21268 | (gdb) |
| 21269 | *stopped,reason="end-stepping-range", |
| 21270 | frame=@{addr="0x000100f4",func="foo",args=[],file="try.c", |
| 21271 | fullname="/home/foo/bar/try.c",line="10"@} |
| 21272 | (gdb) |
| 21273 | @end smallexample |
| 21274 | |
| 21275 | |
| 21276 | @subheading The @code{-exec-until} Command |
| 21277 | @findex -exec-until |
| 21278 | |
| 21279 | @subsubheading Synopsis |
| 21280 | |
| 21281 | @smallexample |
| 21282 | -exec-until [ @var{location} ] |
| 21283 | @end smallexample |
| 21284 | |
| 21285 | Executes the inferior until the @var{location} specified in the |
| 21286 | argument is reached. If there is no argument, the inferior executes |
| 21287 | until a source line greater than the current one is reached. The |
| 21288 | reason for stopping in this case will be @samp{location-reached}. |
| 21289 | |
| 21290 | @subsubheading @value{GDBN} Command |
| 21291 | |
| 21292 | The corresponding @value{GDBN} command is @samp{until}. |
| 21293 | |
| 21294 | @subsubheading Example |
| 21295 | |
| 21296 | @smallexample |
| 21297 | (gdb) |
| 21298 | -exec-until recursive2.c:6 |
| 21299 | ^running |
| 21300 | (gdb) |
| 21301 | x = 55 |
| 21302 | *stopped,reason="location-reached",frame=@{func="main",args=[], |
| 21303 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6"@} |
| 21304 | (gdb) |
| 21305 | @end smallexample |
| 21306 | |
| 21307 | @ignore |
| 21308 | @subheading -file-clear |
| 21309 | Is this going away???? |
| 21310 | @end ignore |
| 21311 | |
| 21312 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 21313 | @node GDB/MI Stack Manipulation |
| 21314 | @section @sc{gdb/mi} Stack Manipulation Commands |
| 21315 | |
| 21316 | |
| 21317 | @subheading The @code{-stack-info-frame} Command |
| 21318 | @findex -stack-info-frame |
| 21319 | |
| 21320 | @subsubheading Synopsis |
| 21321 | |
| 21322 | @smallexample |
| 21323 | -stack-info-frame |
| 21324 | @end smallexample |
| 21325 | |
| 21326 | Get info on the selected frame. |
| 21327 | |
| 21328 | @subsubheading @value{GDBN} Command |
| 21329 | |
| 21330 | The corresponding @value{GDBN} command is @samp{info frame} or @samp{frame} |
| 21331 | (without arguments). |
| 21332 | |
| 21333 | @subsubheading Example |
| 21334 | |
| 21335 | @smallexample |
| 21336 | (gdb) |
| 21337 | -stack-info-frame |
| 21338 | ^done,frame=@{level="1",addr="0x0001076c",func="callee3", |
| 21339 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21340 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@} |
| 21341 | (gdb) |
| 21342 | @end smallexample |
| 21343 | |
| 21344 | @subheading The @code{-stack-info-depth} Command |
| 21345 | @findex -stack-info-depth |
| 21346 | |
| 21347 | @subsubheading Synopsis |
| 21348 | |
| 21349 | @smallexample |
| 21350 | -stack-info-depth [ @var{max-depth} ] |
| 21351 | @end smallexample |
| 21352 | |
| 21353 | Return the depth of the stack. If the integer argument @var{max-depth} |
| 21354 | is specified, do not count beyond @var{max-depth} frames. |
| 21355 | |
| 21356 | @subsubheading @value{GDBN} Command |
| 21357 | |
| 21358 | There's no equivalent @value{GDBN} command. |
| 21359 | |
| 21360 | @subsubheading Example |
| 21361 | |
| 21362 | For a stack with frame levels 0 through 11: |
| 21363 | |
| 21364 | @smallexample |
| 21365 | (gdb) |
| 21366 | -stack-info-depth |
| 21367 | ^done,depth="12" |
| 21368 | (gdb) |
| 21369 | -stack-info-depth 4 |
| 21370 | ^done,depth="4" |
| 21371 | (gdb) |
| 21372 | -stack-info-depth 12 |
| 21373 | ^done,depth="12" |
| 21374 | (gdb) |
| 21375 | -stack-info-depth 11 |
| 21376 | ^done,depth="11" |
| 21377 | (gdb) |
| 21378 | -stack-info-depth 13 |
| 21379 | ^done,depth="12" |
| 21380 | (gdb) |
| 21381 | @end smallexample |
| 21382 | |
| 21383 | @subheading The @code{-stack-list-arguments} Command |
| 21384 | @findex -stack-list-arguments |
| 21385 | |
| 21386 | @subsubheading Synopsis |
| 21387 | |
| 21388 | @smallexample |
| 21389 | -stack-list-arguments @var{show-values} |
| 21390 | [ @var{low-frame} @var{high-frame} ] |
| 21391 | @end smallexample |
| 21392 | |
| 21393 | Display a list of the arguments for the frames between @var{low-frame} |
| 21394 | and @var{high-frame} (inclusive). If @var{low-frame} and |
| 21395 | @var{high-frame} are not provided, list the arguments for the whole |
| 21396 | call stack. If the two arguments are equal, show the single frame |
| 21397 | at the corresponding level. It is an error if @var{low-frame} is |
| 21398 | larger than the actual number of frames. On the other hand, |
| 21399 | @var{high-frame} may be larger than the actual number of frames, in |
| 21400 | which case only existing frames will be returned. |
| 21401 | |
| 21402 | The @var{show-values} argument must have a value of 0 or 1. A value of |
| 21403 | 0 means that only the names of the arguments are listed, a value of 1 |
| 21404 | means that both names and values of the arguments are printed. |
| 21405 | |
| 21406 | @subsubheading @value{GDBN} Command |
| 21407 | |
| 21408 | @value{GDBN} does not have an equivalent command. @code{gdbtk} has a |
| 21409 | @samp{gdb_get_args} command which partially overlaps with the |
| 21410 | functionality of @samp{-stack-list-arguments}. |
| 21411 | |
| 21412 | @subsubheading Example |
| 21413 | |
| 21414 | @smallexample |
| 21415 | (gdb) |
| 21416 | -stack-list-frames |
| 21417 | ^done, |
| 21418 | stack=[ |
| 21419 | frame=@{level="0",addr="0x00010734",func="callee4", |
| 21420 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21421 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}, |
| 21422 | frame=@{level="1",addr="0x0001076c",func="callee3", |
| 21423 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21424 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@}, |
| 21425 | frame=@{level="2",addr="0x0001078c",func="callee2", |
| 21426 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21427 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"@}, |
| 21428 | frame=@{level="3",addr="0x000107b4",func="callee1", |
| 21429 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21430 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"@}, |
| 21431 | frame=@{level="4",addr="0x000107e0",func="main", |
| 21432 | file="../../../devo/gdb/testsuite/gdb.mi/basics.c", |
| 21433 | fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"@}] |
| 21434 | (gdb) |
| 21435 | -stack-list-arguments 0 |
| 21436 | ^done, |
| 21437 | stack-args=[ |
| 21438 | frame=@{level="0",args=[]@}, |
| 21439 | frame=@{level="1",args=[name="strarg"]@}, |
| 21440 | frame=@{level="2",args=[name="intarg",name="strarg"]@}, |
| 21441 | frame=@{level="3",args=[name="intarg",name="strarg",name="fltarg"]@}, |
| 21442 | frame=@{level="4",args=[]@}] |
| 21443 | (gdb) |
| 21444 | -stack-list-arguments 1 |
| 21445 | ^done, |
| 21446 | stack-args=[ |
| 21447 | frame=@{level="0",args=[]@}, |
| 21448 | frame=@{level="1", |
| 21449 | args=[@{name="strarg",value="0x11940 \"A string argument.\""@}]@}, |
| 21450 | frame=@{level="2",args=[ |
| 21451 | @{name="intarg",value="2"@}, |
| 21452 | @{name="strarg",value="0x11940 \"A string argument.\""@}]@}, |
| 21453 | @{frame=@{level="3",args=[ |
| 21454 | @{name="intarg",value="2"@}, |
| 21455 | @{name="strarg",value="0x11940 \"A string argument.\""@}, |
| 21456 | @{name="fltarg",value="3.5"@}]@}, |
| 21457 | frame=@{level="4",args=[]@}] |
| 21458 | (gdb) |
| 21459 | -stack-list-arguments 0 2 2 |
| 21460 | ^done,stack-args=[frame=@{level="2",args=[name="intarg",name="strarg"]@}] |
| 21461 | (gdb) |
| 21462 | -stack-list-arguments 1 2 2 |
| 21463 | ^done,stack-args=[frame=@{level="2", |
| 21464 | args=[@{name="intarg",value="2"@}, |
| 21465 | @{name="strarg",value="0x11940 \"A string argument.\""@}]@}] |
| 21466 | (gdb) |
| 21467 | @end smallexample |
| 21468 | |
| 21469 | @c @subheading -stack-list-exception-handlers |
| 21470 | |
| 21471 | |
| 21472 | @subheading The @code{-stack-list-frames} Command |
| 21473 | @findex -stack-list-frames |
| 21474 | |
| 21475 | @subsubheading Synopsis |
| 21476 | |
| 21477 | @smallexample |
| 21478 | -stack-list-frames [ @var{low-frame} @var{high-frame} ] |
| 21479 | @end smallexample |
| 21480 | |
| 21481 | List the frames currently on the stack. For each frame it displays the |
| 21482 | following info: |
| 21483 | |
| 21484 | @table @samp |
| 21485 | @item @var{level} |
| 21486 | The frame number, 0 being the topmost frame, i.e., the innermost function. |
| 21487 | @item @var{addr} |
| 21488 | The @code{$pc} value for that frame. |
| 21489 | @item @var{func} |
| 21490 | Function name. |
| 21491 | @item @var{file} |
| 21492 | File name of the source file where the function lives. |
| 21493 | @item @var{line} |
| 21494 | Line number corresponding to the @code{$pc}. |
| 21495 | @end table |
| 21496 | |
| 21497 | If invoked without arguments, this command prints a backtrace for the |
| 21498 | whole stack. If given two integer arguments, it shows the frames whose |
| 21499 | levels are between the two arguments (inclusive). If the two arguments |
| 21500 | are equal, it shows the single frame at the corresponding level. It is |
| 21501 | an error if @var{low-frame} is larger than the actual number of |
| 21502 | frames. On the other hand, @var{high-frame} may be larger than the |
| 21503 | actual number of frames, in which case only existing frames will be returned. |
| 21504 | |
| 21505 | @subsubheading @value{GDBN} Command |
| 21506 | |
| 21507 | The corresponding @value{GDBN} commands are @samp{backtrace} and @samp{where}. |
| 21508 | |
| 21509 | @subsubheading Example |
| 21510 | |
| 21511 | Full stack backtrace: |
| 21512 | |
| 21513 | @smallexample |
| 21514 | (gdb) |
| 21515 | -stack-list-frames |
| 21516 | ^done,stack= |
| 21517 | [frame=@{level="0",addr="0x0001076c",func="foo", |
| 21518 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11"@}, |
| 21519 | frame=@{level="1",addr="0x000107a4",func="foo", |
| 21520 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21521 | frame=@{level="2",addr="0x000107a4",func="foo", |
| 21522 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21523 | frame=@{level="3",addr="0x000107a4",func="foo", |
| 21524 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21525 | frame=@{level="4",addr="0x000107a4",func="foo", |
| 21526 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21527 | frame=@{level="5",addr="0x000107a4",func="foo", |
| 21528 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21529 | frame=@{level="6",addr="0x000107a4",func="foo", |
| 21530 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21531 | frame=@{level="7",addr="0x000107a4",func="foo", |
| 21532 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21533 | frame=@{level="8",addr="0x000107a4",func="foo", |
| 21534 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21535 | frame=@{level="9",addr="0x000107a4",func="foo", |
| 21536 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21537 | frame=@{level="10",addr="0x000107a4",func="foo", |
| 21538 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21539 | frame=@{level="11",addr="0x00010738",func="main", |
| 21540 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4"@}] |
| 21541 | (gdb) |
| 21542 | @end smallexample |
| 21543 | |
| 21544 | Show frames between @var{low_frame} and @var{high_frame}: |
| 21545 | |
| 21546 | @smallexample |
| 21547 | (gdb) |
| 21548 | -stack-list-frames 3 5 |
| 21549 | ^done,stack= |
| 21550 | [frame=@{level="3",addr="0x000107a4",func="foo", |
| 21551 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21552 | frame=@{level="4",addr="0x000107a4",func="foo", |
| 21553 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}, |
| 21554 | frame=@{level="5",addr="0x000107a4",func="foo", |
| 21555 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}] |
| 21556 | (gdb) |
| 21557 | @end smallexample |
| 21558 | |
| 21559 | Show a single frame: |
| 21560 | |
| 21561 | @smallexample |
| 21562 | (gdb) |
| 21563 | -stack-list-frames 3 3 |
| 21564 | ^done,stack= |
| 21565 | [frame=@{level="3",addr="0x000107a4",func="foo", |
| 21566 | file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}] |
| 21567 | (gdb) |
| 21568 | @end smallexample |
| 21569 | |
| 21570 | |
| 21571 | @subheading The @code{-stack-list-locals} Command |
| 21572 | @findex -stack-list-locals |
| 21573 | |
| 21574 | @subsubheading Synopsis |
| 21575 | |
| 21576 | @smallexample |
| 21577 | -stack-list-locals @var{print-values} |
| 21578 | @end smallexample |
| 21579 | |
| 21580 | Display the local variable names for the selected frame. If |
| 21581 | @var{print-values} is 0 or @code{--no-values}, print only the names of |
| 21582 | the variables; if it is 1 or @code{--all-values}, print also their |
| 21583 | values; and if it is 2 or @code{--simple-values}, print the name, |
| 21584 | type and value for simple data types and the name and type for arrays, |
| 21585 | structures and unions. In this last case, a frontend can immediately |
| 21586 | display the value of simple data types and create variable objects for |
| 21587 | other data types when the user wishes to explore their values in |
| 21588 | more detail. |
| 21589 | |
| 21590 | @subsubheading @value{GDBN} Command |
| 21591 | |
| 21592 | @samp{info locals} in @value{GDBN}, @samp{gdb_get_locals} in @code{gdbtk}. |
| 21593 | |
| 21594 | @subsubheading Example |
| 21595 | |
| 21596 | @smallexample |
| 21597 | (gdb) |
| 21598 | -stack-list-locals 0 |
| 21599 | ^done,locals=[name="A",name="B",name="C"] |
| 21600 | (gdb) |
| 21601 | -stack-list-locals --all-values |
| 21602 | ^done,locals=[@{name="A",value="1"@},@{name="B",value="2"@}, |
| 21603 | @{name="C",value="@{1, 2, 3@}"@}] |
| 21604 | -stack-list-locals --simple-values |
| 21605 | ^done,locals=[@{name="A",type="int",value="1"@}, |
| 21606 | @{name="B",type="int",value="2"@},@{name="C",type="int [3]"@}] |
| 21607 | (gdb) |
| 21608 | @end smallexample |
| 21609 | |
| 21610 | |
| 21611 | @subheading The @code{-stack-select-frame} Command |
| 21612 | @findex -stack-select-frame |
| 21613 | |
| 21614 | @subsubheading Synopsis |
| 21615 | |
| 21616 | @smallexample |
| 21617 | -stack-select-frame @var{framenum} |
| 21618 | @end smallexample |
| 21619 | |
| 21620 | Change the selected frame. Select a different frame @var{framenum} on |
| 21621 | the stack. |
| 21622 | |
| 21623 | This command in deprecated in favor of passing the @samp{--frame} |
| 21624 | option to every command. |
| 21625 | |
| 21626 | @subsubheading @value{GDBN} Command |
| 21627 | |
| 21628 | The corresponding @value{GDBN} commands are @samp{frame}, @samp{up}, |
| 21629 | @samp{down}, @samp{select-frame}, @samp{up-silent}, and @samp{down-silent}. |
| 21630 | |
| 21631 | @subsubheading Example |
| 21632 | |
| 21633 | @smallexample |
| 21634 | (gdb) |
| 21635 | -stack-select-frame 2 |
| 21636 | ^done |
| 21637 | (gdb) |
| 21638 | @end smallexample |
| 21639 | |
| 21640 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 21641 | @node GDB/MI Variable Objects |
| 21642 | @section @sc{gdb/mi} Variable Objects |
| 21643 | |
| 21644 | @ignore |
| 21645 | |
| 21646 | @subheading Motivation for Variable Objects in @sc{gdb/mi} |
| 21647 | |
| 21648 | For the implementation of a variable debugger window (locals, watched |
| 21649 | expressions, etc.), we are proposing the adaptation of the existing code |
| 21650 | used by @code{Insight}. |
| 21651 | |
| 21652 | The two main reasons for that are: |
| 21653 | |
| 21654 | @enumerate 1 |
| 21655 | @item |
| 21656 | It has been proven in practice (it is already on its second generation). |
| 21657 | |
| 21658 | @item |
| 21659 | It will shorten development time (needless to say how important it is |
| 21660 | now). |
| 21661 | @end enumerate |
| 21662 | |
| 21663 | The original interface was designed to be used by Tcl code, so it was |
| 21664 | slightly changed so it could be used through @sc{gdb/mi}. This section |
| 21665 | describes the @sc{gdb/mi} operations that will be available and gives some |
| 21666 | hints about their use. |
| 21667 | |
| 21668 | @emph{Note}: In addition to the set of operations described here, we |
| 21669 | expect the @sc{gui} implementation of a variable window to require, at |
| 21670 | least, the following operations: |
| 21671 | |
| 21672 | @itemize @bullet |
| 21673 | @item @code{-gdb-show} @code{output-radix} |
| 21674 | @item @code{-stack-list-arguments} |
| 21675 | @item @code{-stack-list-locals} |
| 21676 | @item @code{-stack-select-frame} |
| 21677 | @end itemize |
| 21678 | |
| 21679 | @end ignore |
| 21680 | |
| 21681 | @subheading Introduction to Variable Objects |
| 21682 | |
| 21683 | @cindex variable objects in @sc{gdb/mi} |
| 21684 | |
| 21685 | Variable objects are "object-oriented" MI interface for examining and |
| 21686 | changing values of expressions. Unlike some other MI interfaces that |
| 21687 | work with expressions, variable objects are specifically designed for |
| 21688 | simple and efficient presentation in the frontend. A variable object |
| 21689 | is identified by string name. When a variable object is created, the |
| 21690 | frontend specifies the expression for that variable object. The |
| 21691 | expression can be a simple variable, or it can be an arbitrary complex |
| 21692 | expression, and can even involve CPU registers. After creating a |
| 21693 | variable object, the frontend can invoke other variable object |
| 21694 | operations---for example to obtain or change the value of a variable |
| 21695 | object, or to change display format. |
| 21696 | |
| 21697 | Variable objects have hierarchical tree structure. Any variable object |
| 21698 | that corresponds to a composite type, such as structure in C, has |
| 21699 | a number of child variable objects, for example corresponding to each |
| 21700 | element of a structure. A child variable object can itself have |
| 21701 | children, recursively. Recursion ends when we reach |
| 21702 | leaf variable objects, which always have built-in types. Child variable |
| 21703 | objects are created only by explicit request, so if a frontend |
| 21704 | is not interested in the children of a particular variable object, no |
| 21705 | child will be created. |
| 21706 | |
| 21707 | For a leaf variable object it is possible to obtain its value as a |
| 21708 | string, or set the value from a string. String value can be also |
| 21709 | obtained for a non-leaf variable object, but it's generally a string |
| 21710 | that only indicates the type of the object, and does not list its |
| 21711 | contents. Assignment to a non-leaf variable object is not allowed. |
| 21712 | |
| 21713 | A frontend does not need to read the values of all variable objects each time |
| 21714 | the program stops. Instead, MI provides an update command that lists all |
| 21715 | variable objects whose values has changed since the last update |
| 21716 | operation. This considerably reduces the amount of data that must |
| 21717 | be transferred to the frontend. As noted above, children variable |
| 21718 | objects are created on demand, and only leaf variable objects have a |
| 21719 | real value. As result, gdb will read target memory only for leaf |
| 21720 | variables that frontend has created. |
| 21721 | |
| 21722 | The automatic update is not always desirable. For example, a frontend |
| 21723 | might want to keep a value of some expression for future reference, |
| 21724 | and never update it. For another example, fetching memory is |
| 21725 | relatively slow for embedded targets, so a frontend might want |
| 21726 | to disable automatic update for the variables that are either not |
| 21727 | visible on the screen, or ``closed''. This is possible using so |
| 21728 | called ``frozen variable objects''. Such variable objects are never |
| 21729 | implicitly updated. |
| 21730 | |
| 21731 | Variable objects can be either @dfn{fixed} or @dfn{floating}. For the |
| 21732 | fixed variable object, the expression is parsed when the variable |
| 21733 | object is created, including associating identifiers to specific |
| 21734 | variables. The meaning of expression never changes. For a floating |
| 21735 | variable object the values of variables whose names appear in the |
| 21736 | expressions are re-evaluated every time in the context of the current |
| 21737 | frame. Consider this example: |
| 21738 | |
| 21739 | @smallexample |
| 21740 | void do_work(...) |
| 21741 | @{ |
| 21742 | struct work_state state; |
| 21743 | |
| 21744 | if (...) |
| 21745 | do_work(...); |
| 21746 | @} |
| 21747 | @end smallexample |
| 21748 | |
| 21749 | If a fixed variable object for the @code{state} variable is created in |
| 21750 | this function, and we enter the recursive call, the the variable |
| 21751 | object will report the value of @code{state} in the top-level |
| 21752 | @code{do_work} invocation. On the other hand, a floating variable |
| 21753 | object will report the value of @code{state} in the current frame. |
| 21754 | |
| 21755 | If an expression specified when creating a fixed variable object |
| 21756 | refers to a local variable, the variable object becomes bound to the |
| 21757 | thread and frame in which the variable object is created. When such |
| 21758 | variable object is updated, @value{GDBN} makes sure that the |
| 21759 | thread/frame combination the variable object is bound to still exists, |
| 21760 | and re-evaluates the variable object in context of that thread/frame. |
| 21761 | |
| 21762 | The following is the complete set of @sc{gdb/mi} operations defined to |
| 21763 | access this functionality: |
| 21764 | |
| 21765 | @multitable @columnfractions .4 .6 |
| 21766 | @item @strong{Operation} |
| 21767 | @tab @strong{Description} |
| 21768 | |
| 21769 | @item @code{-var-create} |
| 21770 | @tab create a variable object |
| 21771 | @item @code{-var-delete} |
| 21772 | @tab delete the variable object and/or its children |
| 21773 | @item @code{-var-set-format} |
| 21774 | @tab set the display format of this variable |
| 21775 | @item @code{-var-show-format} |
| 21776 | @tab show the display format of this variable |
| 21777 | @item @code{-var-info-num-children} |
| 21778 | @tab tells how many children this object has |
| 21779 | @item @code{-var-list-children} |
| 21780 | @tab return a list of the object's children |
| 21781 | @item @code{-var-info-type} |
| 21782 | @tab show the type of this variable object |
| 21783 | @item @code{-var-info-expression} |
| 21784 | @tab print parent-relative expression that this variable object represents |
| 21785 | @item @code{-var-info-path-expression} |
| 21786 | @tab print full expression that this variable object represents |
| 21787 | @item @code{-var-show-attributes} |
| 21788 | @tab is this variable editable? does it exist here? |
| 21789 | @item @code{-var-evaluate-expression} |
| 21790 | @tab get the value of this variable |
| 21791 | @item @code{-var-assign} |
| 21792 | @tab set the value of this variable |
| 21793 | @item @code{-var-update} |
| 21794 | @tab update the variable and its children |
| 21795 | @item @code{-var-set-frozen} |
| 21796 | @tab set frozeness attribute |
| 21797 | @end multitable |
| 21798 | |
| 21799 | In the next subsection we describe each operation in detail and suggest |
| 21800 | how it can be used. |
| 21801 | |
| 21802 | @subheading Description And Use of Operations on Variable Objects |
| 21803 | |
| 21804 | @subheading The @code{-var-create} Command |
| 21805 | @findex -var-create |
| 21806 | |
| 21807 | @subsubheading Synopsis |
| 21808 | |
| 21809 | @smallexample |
| 21810 | -var-create @{@var{name} | "-"@} |
| 21811 | @{@var{frame-addr} | "*" | "@@"@} @var{expression} |
| 21812 | @end smallexample |
| 21813 | |
| 21814 | This operation creates a variable object, which allows the monitoring of |
| 21815 | a variable, the result of an expression, a memory cell or a CPU |
| 21816 | register. |
| 21817 | |
| 21818 | The @var{name} parameter is the string by which the object can be |
| 21819 | referenced. It must be unique. If @samp{-} is specified, the varobj |
| 21820 | system will generate a string ``varNNNNNN'' automatically. It will be |
| 21821 | unique provided that one does not specify @var{name} of that format. |
| 21822 | The command fails if a duplicate name is found. |
| 21823 | |
| 21824 | The frame under which the expression should be evaluated can be |
| 21825 | specified by @var{frame-addr}. A @samp{*} indicates that the current |
| 21826 | frame should be used. A @samp{@@} indicates that a floating variable |
| 21827 | object must be created. |
| 21828 | |
| 21829 | @var{expression} is any expression valid on the current language set (must not |
| 21830 | begin with a @samp{*}), or one of the following: |
| 21831 | |
| 21832 | @itemize @bullet |
| 21833 | @item |
| 21834 | @samp{*@var{addr}}, where @var{addr} is the address of a memory cell |
| 21835 | |
| 21836 | @item |
| 21837 | @samp{*@var{addr}-@var{addr}} --- a memory address range (TBD) |
| 21838 | |
| 21839 | @item |
| 21840 | @samp{$@var{regname}} --- a CPU register name |
| 21841 | @end itemize |
| 21842 | |
| 21843 | @subsubheading Result |
| 21844 | |
| 21845 | This operation returns the name, number of children and the type of the |
| 21846 | object created. Type is returned as a string as the ones generated by |
| 21847 | the @value{GDBN} CLI. If a fixed variable object is bound to a |
| 21848 | specific thread, the thread is is also printed: |
| 21849 | |
| 21850 | @smallexample |
| 21851 | name="@var{name}",numchild="@var{N}",type="@var{type}",thread-id="@var{M}" |
| 21852 | @end smallexample |
| 21853 | |
| 21854 | |
| 21855 | @subheading The @code{-var-delete} Command |
| 21856 | @findex -var-delete |
| 21857 | |
| 21858 | @subsubheading Synopsis |
| 21859 | |
| 21860 | @smallexample |
| 21861 | -var-delete [ -c ] @var{name} |
| 21862 | @end smallexample |
| 21863 | |
| 21864 | Deletes a previously created variable object and all of its children. |
| 21865 | With the @samp{-c} option, just deletes the children. |
| 21866 | |
| 21867 | Returns an error if the object @var{name} is not found. |
| 21868 | |
| 21869 | |
| 21870 | @subheading The @code{-var-set-format} Command |
| 21871 | @findex -var-set-format |
| 21872 | |
| 21873 | @subsubheading Synopsis |
| 21874 | |
| 21875 | @smallexample |
| 21876 | -var-set-format @var{name} @var{format-spec} |
| 21877 | @end smallexample |
| 21878 | |
| 21879 | Sets the output format for the value of the object @var{name} to be |
| 21880 | @var{format-spec}. |
| 21881 | |
| 21882 | @anchor{-var-set-format} |
| 21883 | The syntax for the @var{format-spec} is as follows: |
| 21884 | |
| 21885 | @smallexample |
| 21886 | @var{format-spec} @expansion{} |
| 21887 | @{binary | decimal | hexadecimal | octal | natural@} |
| 21888 | @end smallexample |
| 21889 | |
| 21890 | The natural format is the default format choosen automatically |
| 21891 | based on the variable type (like decimal for an @code{int}, hex |
| 21892 | for pointers, etc.). |
| 21893 | |
| 21894 | For a variable with children, the format is set only on the |
| 21895 | variable itself, and the children are not affected. |
| 21896 | |
| 21897 | @subheading The @code{-var-show-format} Command |
| 21898 | @findex -var-show-format |
| 21899 | |
| 21900 | @subsubheading Synopsis |
| 21901 | |
| 21902 | @smallexample |
| 21903 | -var-show-format @var{name} |
| 21904 | @end smallexample |
| 21905 | |
| 21906 | Returns the format used to display the value of the object @var{name}. |
| 21907 | |
| 21908 | @smallexample |
| 21909 | @var{format} @expansion{} |
| 21910 | @var{format-spec} |
| 21911 | @end smallexample |
| 21912 | |
| 21913 | |
| 21914 | @subheading The @code{-var-info-num-children} Command |
| 21915 | @findex -var-info-num-children |
| 21916 | |
| 21917 | @subsubheading Synopsis |
| 21918 | |
| 21919 | @smallexample |
| 21920 | -var-info-num-children @var{name} |
| 21921 | @end smallexample |
| 21922 | |
| 21923 | Returns the number of children of a variable object @var{name}: |
| 21924 | |
| 21925 | @smallexample |
| 21926 | numchild=@var{n} |
| 21927 | @end smallexample |
| 21928 | |
| 21929 | |
| 21930 | @subheading The @code{-var-list-children} Command |
| 21931 | @findex -var-list-children |
| 21932 | |
| 21933 | @subsubheading Synopsis |
| 21934 | |
| 21935 | @smallexample |
| 21936 | -var-list-children [@var{print-values}] @var{name} |
| 21937 | @end smallexample |
| 21938 | @anchor{-var-list-children} |
| 21939 | |
| 21940 | Return a list of the children of the specified variable object and |
| 21941 | create variable objects for them, if they do not already exist. With |
| 21942 | a single argument or if @var{print-values} has a value for of 0 or |
| 21943 | @code{--no-values}, print only the names of the variables; if |
| 21944 | @var{print-values} is 1 or @code{--all-values}, also print their |
| 21945 | values; and if it is 2 or @code{--simple-values} print the name and |
| 21946 | value for simple data types and just the name for arrays, structures |
| 21947 | and unions. |
| 21948 | |
| 21949 | @subsubheading Example |
| 21950 | |
| 21951 | @smallexample |
| 21952 | (gdb) |
| 21953 | -var-list-children n |
| 21954 | ^done,numchild=@var{n},children=[@{name=@var{name}, |
| 21955 | numchild=@var{n},type=@var{type}@},@r{(repeats N times)}] |
| 21956 | (gdb) |
| 21957 | -var-list-children --all-values n |
| 21958 | ^done,numchild=@var{n},children=[@{name=@var{name}, |
| 21959 | numchild=@var{n},value=@var{value},type=@var{type}@},@r{(repeats N times)}] |
| 21960 | @end smallexample |
| 21961 | |
| 21962 | |
| 21963 | @subheading The @code{-var-info-type} Command |
| 21964 | @findex -var-info-type |
| 21965 | |
| 21966 | @subsubheading Synopsis |
| 21967 | |
| 21968 | @smallexample |
| 21969 | -var-info-type @var{name} |
| 21970 | @end smallexample |
| 21971 | |
| 21972 | Returns the type of the specified variable @var{name}. The type is |
| 21973 | returned as a string in the same format as it is output by the |
| 21974 | @value{GDBN} CLI: |
| 21975 | |
| 21976 | @smallexample |
| 21977 | type=@var{typename} |
| 21978 | @end smallexample |
| 21979 | |
| 21980 | |
| 21981 | @subheading The @code{-var-info-expression} Command |
| 21982 | @findex -var-info-expression |
| 21983 | |
| 21984 | @subsubheading Synopsis |
| 21985 | |
| 21986 | @smallexample |
| 21987 | -var-info-expression @var{name} |
| 21988 | @end smallexample |
| 21989 | |
| 21990 | Returns a string that is suitable for presenting this |
| 21991 | variable object in user interface. The string is generally |
| 21992 | not valid expression in the current language, and cannot be evaluated. |
| 21993 | |
| 21994 | For example, if @code{a} is an array, and variable object |
| 21995 | @code{A} was created for @code{a}, then we'll get this output: |
| 21996 | |
| 21997 | @smallexample |
| 21998 | (gdb) -var-info-expression A.1 |
| 21999 | ^done,lang="C",exp="1" |
| 22000 | @end smallexample |
| 22001 | |
| 22002 | @noindent |
| 22003 | Here, the values of @code{lang} can be @code{@{"C" | "C++" | "Java"@}}. |
| 22004 | |
| 22005 | Note that the output of the @code{-var-list-children} command also |
| 22006 | includes those expressions, so the @code{-var-info-expression} command |
| 22007 | is of limited use. |
| 22008 | |
| 22009 | @subheading The @code{-var-info-path-expression} Command |
| 22010 | @findex -var-info-path-expression |
| 22011 | |
| 22012 | @subsubheading Synopsis |
| 22013 | |
| 22014 | @smallexample |
| 22015 | -var-info-path-expression @var{name} |
| 22016 | @end smallexample |
| 22017 | |
| 22018 | Returns an expression that can be evaluated in the current |
| 22019 | context and will yield the same value that a variable object has. |
| 22020 | Compare this with the @code{-var-info-expression} command, which |
| 22021 | result can be used only for UI presentation. Typical use of |
| 22022 | the @code{-var-info-path-expression} command is creating a |
| 22023 | watchpoint from a variable object. |
| 22024 | |
| 22025 | For example, suppose @code{C} is a C@t{++} class, derived from class |
| 22026 | @code{Base}, and that the @code{Base} class has a member called |
| 22027 | @code{m_size}. Assume a variable @code{c} is has the type of |
| 22028 | @code{C} and a variable object @code{C} was created for variable |
| 22029 | @code{c}. Then, we'll get this output: |
| 22030 | @smallexample |
| 22031 | (gdb) -var-info-path-expression C.Base.public.m_size |
| 22032 | ^done,path_expr=((Base)c).m_size) |
| 22033 | @end smallexample |
| 22034 | |
| 22035 | @subheading The @code{-var-show-attributes} Command |
| 22036 | @findex -var-show-attributes |
| 22037 | |
| 22038 | @subsubheading Synopsis |
| 22039 | |
| 22040 | @smallexample |
| 22041 | -var-show-attributes @var{name} |
| 22042 | @end smallexample |
| 22043 | |
| 22044 | List attributes of the specified variable object @var{name}: |
| 22045 | |
| 22046 | @smallexample |
| 22047 | status=@var{attr} [ ( ,@var{attr} )* ] |
| 22048 | @end smallexample |
| 22049 | |
| 22050 | @noindent |
| 22051 | where @var{attr} is @code{@{ @{ editable | noneditable @} | TBD @}}. |
| 22052 | |
| 22053 | @subheading The @code{-var-evaluate-expression} Command |
| 22054 | @findex -var-evaluate-expression |
| 22055 | |
| 22056 | @subsubheading Synopsis |
| 22057 | |
| 22058 | @smallexample |
| 22059 | -var-evaluate-expression [-f @var{format-spec}] @var{name} |
| 22060 | @end smallexample |
| 22061 | |
| 22062 | Evaluates the expression that is represented by the specified variable |
| 22063 | object and returns its value as a string. The format of the string |
| 22064 | can be specified with the @samp{-f} option. The possible values of |
| 22065 | this option are the same as for @code{-var-set-format} |
| 22066 | (@pxref{-var-set-format}). If the @samp{-f} option is not specified, |
| 22067 | the current display format will be used. The current display format |
| 22068 | can be changed using the @code{-var-set-format} command. |
| 22069 | |
| 22070 | @smallexample |
| 22071 | value=@var{value} |
| 22072 | @end smallexample |
| 22073 | |
| 22074 | Note that one must invoke @code{-var-list-children} for a variable |
| 22075 | before the value of a child variable can be evaluated. |
| 22076 | |
| 22077 | @subheading The @code{-var-assign} Command |
| 22078 | @findex -var-assign |
| 22079 | |
| 22080 | @subsubheading Synopsis |
| 22081 | |
| 22082 | @smallexample |
| 22083 | -var-assign @var{name} @var{expression} |
| 22084 | @end smallexample |
| 22085 | |
| 22086 | Assigns the value of @var{expression} to the variable object specified |
| 22087 | by @var{name}. The object must be @samp{editable}. If the variable's |
| 22088 | value is altered by the assign, the variable will show up in any |
| 22089 | subsequent @code{-var-update} list. |
| 22090 | |
| 22091 | @subsubheading Example |
| 22092 | |
| 22093 | @smallexample |
| 22094 | (gdb) |
| 22095 | -var-assign var1 3 |
| 22096 | ^done,value="3" |
| 22097 | (gdb) |
| 22098 | -var-update * |
| 22099 | ^done,changelist=[@{name="var1",in_scope="true",type_changed="false"@}] |
| 22100 | (gdb) |
| 22101 | @end smallexample |
| 22102 | |
| 22103 | @subheading The @code{-var-update} Command |
| 22104 | @findex -var-update |
| 22105 | |
| 22106 | @subsubheading Synopsis |
| 22107 | |
| 22108 | @smallexample |
| 22109 | -var-update [@var{print-values}] @{@var{name} | "*"@} |
| 22110 | @end smallexample |
| 22111 | |
| 22112 | Reevaluate the expressions corresponding to the variable object |
| 22113 | @var{name} and all its direct and indirect children, and return the |
| 22114 | list of variable objects whose values have changed; @var{name} must |
| 22115 | be a root variable object. Here, ``changed'' means that the result of |
| 22116 | @code{-var-evaluate-expression} before and after the |
| 22117 | @code{-var-update} is different. If @samp{*} is used as the variable |
| 22118 | object names, all existing variable objects are updated, except |
| 22119 | for frozen ones (@pxref{-var-set-frozen}). The option |
| 22120 | @var{print-values} determines whether both names and values, or just |
| 22121 | names are printed. The possible values of this option are the same |
| 22122 | as for @code{-var-list-children} (@pxref{-var-list-children}). It is |
| 22123 | recommended to use the @samp{--all-values} option, to reduce the |
| 22124 | number of MI commands needed on each program stop. |
| 22125 | |
| 22126 | With the @samp{*} parameter, if a variable object is bound to a |
| 22127 | currently running thread, it will not be updated, without any |
| 22128 | diagnostic. |
| 22129 | |
| 22130 | @subsubheading Example |
| 22131 | |
| 22132 | @smallexample |
| 22133 | (gdb) |
| 22134 | -var-assign var1 3 |
| 22135 | ^done,value="3" |
| 22136 | (gdb) |
| 22137 | -var-update --all-values var1 |
| 22138 | ^done,changelist=[@{name="var1",value="3",in_scope="true", |
| 22139 | type_changed="false"@}] |
| 22140 | (gdb) |
| 22141 | @end smallexample |
| 22142 | |
| 22143 | @anchor{-var-update} |
| 22144 | The field in_scope may take three values: |
| 22145 | |
| 22146 | @table @code |
| 22147 | @item "true" |
| 22148 | The variable object's current value is valid. |
| 22149 | |
| 22150 | @item "false" |
| 22151 | The variable object does not currently hold a valid value but it may |
| 22152 | hold one in the future if its associated expression comes back into |
| 22153 | scope. |
| 22154 | |
| 22155 | @item "invalid" |
| 22156 | The variable object no longer holds a valid value. |
| 22157 | This can occur when the executable file being debugged has changed, |
| 22158 | either through recompilation or by using the @value{GDBN} @code{file} |
| 22159 | command. The front end should normally choose to delete these variable |
| 22160 | objects. |
| 22161 | @end table |
| 22162 | |
| 22163 | In the future new values may be added to this list so the front should |
| 22164 | be prepared for this possibility. @xref{GDB/MI Development and Front Ends, ,@sc{GDB/MI} Development and Front Ends}. |
| 22165 | |
| 22166 | @subheading The @code{-var-set-frozen} Command |
| 22167 | @findex -var-set-frozen |
| 22168 | @anchor{-var-set-frozen} |
| 22169 | |
| 22170 | @subsubheading Synopsis |
| 22171 | |
| 22172 | @smallexample |
| 22173 | -var-set-frozen @var{name} @var{flag} |
| 22174 | @end smallexample |
| 22175 | |
| 22176 | Set the frozenness flag on the variable object @var{name}. The |
| 22177 | @var{flag} parameter should be either @samp{1} to make the variable |
| 22178 | frozen or @samp{0} to make it unfrozen. If a variable object is |
| 22179 | frozen, then neither itself, nor any of its children, are |
| 22180 | implicitly updated by @code{-var-update} of |
| 22181 | a parent variable or by @code{-var-update *}. Only |
| 22182 | @code{-var-update} of the variable itself will update its value and |
| 22183 | values of its children. After a variable object is unfrozen, it is |
| 22184 | implicitly updated by all subsequent @code{-var-update} operations. |
| 22185 | Unfreezing a variable does not update it, only subsequent |
| 22186 | @code{-var-update} does. |
| 22187 | |
| 22188 | @subsubheading Example |
| 22189 | |
| 22190 | @smallexample |
| 22191 | (gdb) |
| 22192 | -var-set-frozen V 1 |
| 22193 | ^done |
| 22194 | (gdb) |
| 22195 | @end smallexample |
| 22196 | |
| 22197 | |
| 22198 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 22199 | @node GDB/MI Data Manipulation |
| 22200 | @section @sc{gdb/mi} Data Manipulation |
| 22201 | |
| 22202 | @cindex data manipulation, in @sc{gdb/mi} |
| 22203 | @cindex @sc{gdb/mi}, data manipulation |
| 22204 | This section describes the @sc{gdb/mi} commands that manipulate data: |
| 22205 | examine memory and registers, evaluate expressions, etc. |
| 22206 | |
| 22207 | @c REMOVED FROM THE INTERFACE. |
| 22208 | @c @subheading -data-assign |
| 22209 | @c Change the value of a program variable. Plenty of side effects. |
| 22210 | @c @subsubheading GDB Command |
| 22211 | @c set variable |
| 22212 | @c @subsubheading Example |
| 22213 | @c N.A. |
| 22214 | |
| 22215 | @subheading The @code{-data-disassemble} Command |
| 22216 | @findex -data-disassemble |
| 22217 | |
| 22218 | @subsubheading Synopsis |
| 22219 | |
| 22220 | @smallexample |
| 22221 | -data-disassemble |
| 22222 | [ -s @var{start-addr} -e @var{end-addr} ] |
| 22223 | | [ -f @var{filename} -l @var{linenum} [ -n @var{lines} ] ] |
| 22224 | -- @var{mode} |
| 22225 | @end smallexample |
| 22226 | |
| 22227 | @noindent |
| 22228 | Where: |
| 22229 | |
| 22230 | @table @samp |
| 22231 | @item @var{start-addr} |
| 22232 | is the beginning address (or @code{$pc}) |
| 22233 | @item @var{end-addr} |
| 22234 | is the end address |
| 22235 | @item @var{filename} |
| 22236 | is the name of the file to disassemble |
| 22237 | @item @var{linenum} |
| 22238 | is the line number to disassemble around |
| 22239 | @item @var{lines} |
| 22240 | is the number of disassembly lines to be produced. If it is -1, |
| 22241 | the whole function will be disassembled, in case no @var{end-addr} is |
| 22242 | specified. If @var{end-addr} is specified as a non-zero value, and |
| 22243 | @var{lines} is lower than the number of disassembly lines between |
| 22244 | @var{start-addr} and @var{end-addr}, only @var{lines} lines are |
| 22245 | displayed; if @var{lines} is higher than the number of lines between |
| 22246 | @var{start-addr} and @var{end-addr}, only the lines up to @var{end-addr} |
| 22247 | are displayed. |
| 22248 | @item @var{mode} |
| 22249 | is either 0 (meaning only disassembly) or 1 (meaning mixed source and |
| 22250 | disassembly). |
| 22251 | @end table |
| 22252 | |
| 22253 | @subsubheading Result |
| 22254 | |
| 22255 | The output for each instruction is composed of four fields: |
| 22256 | |
| 22257 | @itemize @bullet |
| 22258 | @item Address |
| 22259 | @item Func-name |
| 22260 | @item Offset |
| 22261 | @item Instruction |
| 22262 | @end itemize |
| 22263 | |
| 22264 | Note that whatever included in the instruction field, is not manipulated |
| 22265 | directly by @sc{gdb/mi}, i.e., it is not possible to adjust its format. |
| 22266 | |
| 22267 | @subsubheading @value{GDBN} Command |
| 22268 | |
| 22269 | There's no direct mapping from this command to the CLI. |
| 22270 | |
| 22271 | @subsubheading Example |
| 22272 | |
| 22273 | Disassemble from the current value of @code{$pc} to @code{$pc + 20}: |
| 22274 | |
| 22275 | @smallexample |
| 22276 | (gdb) |
| 22277 | -data-disassemble -s $pc -e "$pc + 20" -- 0 |
| 22278 | ^done, |
| 22279 | asm_insns=[ |
| 22280 | @{address="0x000107c0",func-name="main",offset="4", |
| 22281 | inst="mov 2, %o0"@}, |
| 22282 | @{address="0x000107c4",func-name="main",offset="8", |
| 22283 | inst="sethi %hi(0x11800), %o2"@}, |
| 22284 | @{address="0x000107c8",func-name="main",offset="12", |
| 22285 | inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"@}, |
| 22286 | @{address="0x000107cc",func-name="main",offset="16", |
| 22287 | inst="sethi %hi(0x11800), %o2"@}, |
| 22288 | @{address="0x000107d0",func-name="main",offset="20", |
| 22289 | inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"@}] |
| 22290 | (gdb) |
| 22291 | @end smallexample |
| 22292 | |
| 22293 | Disassemble the whole @code{main} function. Line 32 is part of |
| 22294 | @code{main}. |
| 22295 | |
| 22296 | @smallexample |
| 22297 | -data-disassemble -f basics.c -l 32 -- 0 |
| 22298 | ^done,asm_insns=[ |
| 22299 | @{address="0x000107bc",func-name="main",offset="0", |
| 22300 | inst="save %sp, -112, %sp"@}, |
| 22301 | @{address="0x000107c0",func-name="main",offset="4", |
| 22302 | inst="mov 2, %o0"@}, |
| 22303 | @{address="0x000107c4",func-name="main",offset="8", |
| 22304 | inst="sethi %hi(0x11800), %o2"@}, |
| 22305 | [@dots{}] |
| 22306 | @{address="0x0001081c",func-name="main",offset="96",inst="ret "@}, |
| 22307 | @{address="0x00010820",func-name="main",offset="100",inst="restore "@}] |
| 22308 | (gdb) |
| 22309 | @end smallexample |
| 22310 | |
| 22311 | Disassemble 3 instructions from the start of @code{main}: |
| 22312 | |
| 22313 | @smallexample |
| 22314 | (gdb) |
| 22315 | -data-disassemble -f basics.c -l 32 -n 3 -- 0 |
| 22316 | ^done,asm_insns=[ |
| 22317 | @{address="0x000107bc",func-name="main",offset="0", |
| 22318 | inst="save %sp, -112, %sp"@}, |
| 22319 | @{address="0x000107c0",func-name="main",offset="4", |
| 22320 | inst="mov 2, %o0"@}, |
| 22321 | @{address="0x000107c4",func-name="main",offset="8", |
| 22322 | inst="sethi %hi(0x11800), %o2"@}] |
| 22323 | (gdb) |
| 22324 | @end smallexample |
| 22325 | |
| 22326 | Disassemble 3 instructions from the start of @code{main} in mixed mode: |
| 22327 | |
| 22328 | @smallexample |
| 22329 | (gdb) |
| 22330 | -data-disassemble -f basics.c -l 32 -n 3 -- 1 |
| 22331 | ^done,asm_insns=[ |
| 22332 | src_and_asm_line=@{line="31", |
| 22333 | file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \ |
| 22334 | testsuite/gdb.mi/basics.c",line_asm_insn=[ |
| 22335 | @{address="0x000107bc",func-name="main",offset="0", |
| 22336 | inst="save %sp, -112, %sp"@}]@}, |
| 22337 | src_and_asm_line=@{line="32", |
| 22338 | file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \ |
| 22339 | testsuite/gdb.mi/basics.c",line_asm_insn=[ |
| 22340 | @{address="0x000107c0",func-name="main",offset="4", |
| 22341 | inst="mov 2, %o0"@}, |
| 22342 | @{address="0x000107c4",func-name="main",offset="8", |
| 22343 | inst="sethi %hi(0x11800), %o2"@}]@}] |
| 22344 | (gdb) |
| 22345 | @end smallexample |
| 22346 | |
| 22347 | |
| 22348 | @subheading The @code{-data-evaluate-expression} Command |
| 22349 | @findex -data-evaluate-expression |
| 22350 | |
| 22351 | @subsubheading Synopsis |
| 22352 | |
| 22353 | @smallexample |
| 22354 | -data-evaluate-expression @var{expr} |
| 22355 | @end smallexample |
| 22356 | |
| 22357 | Evaluate @var{expr} as an expression. The expression could contain an |
| 22358 | inferior function call. The function call will execute synchronously. |
| 22359 | If the expression contains spaces, it must be enclosed in double quotes. |
| 22360 | |
| 22361 | @subsubheading @value{GDBN} Command |
| 22362 | |
| 22363 | The corresponding @value{GDBN} commands are @samp{print}, @samp{output}, and |
| 22364 | @samp{call}. In @code{gdbtk} only, there's a corresponding |
| 22365 | @samp{gdb_eval} command. |
| 22366 | |
| 22367 | @subsubheading Example |
| 22368 | |
| 22369 | In the following example, the numbers that precede the commands are the |
| 22370 | @dfn{tokens} described in @ref{GDB/MI Command Syntax, ,@sc{gdb/mi} |
| 22371 | Command Syntax}. Notice how @sc{gdb/mi} returns the same tokens in its |
| 22372 | output. |
| 22373 | |
| 22374 | @smallexample |
| 22375 | 211-data-evaluate-expression A |
| 22376 | 211^done,value="1" |
| 22377 | (gdb) |
| 22378 | 311-data-evaluate-expression &A |
| 22379 | 311^done,value="0xefffeb7c" |
| 22380 | (gdb) |
| 22381 | 411-data-evaluate-expression A+3 |
| 22382 | 411^done,value="4" |
| 22383 | (gdb) |
| 22384 | 511-data-evaluate-expression "A + 3" |
| 22385 | 511^done,value="4" |
| 22386 | (gdb) |
| 22387 | @end smallexample |
| 22388 | |
| 22389 | |
| 22390 | @subheading The @code{-data-list-changed-registers} Command |
| 22391 | @findex -data-list-changed-registers |
| 22392 | |
| 22393 | @subsubheading Synopsis |
| 22394 | |
| 22395 | @smallexample |
| 22396 | -data-list-changed-registers |
| 22397 | @end smallexample |
| 22398 | |
| 22399 | Display a list of the registers that have changed. |
| 22400 | |
| 22401 | @subsubheading @value{GDBN} Command |
| 22402 | |
| 22403 | @value{GDBN} doesn't have a direct analog for this command; @code{gdbtk} |
| 22404 | has the corresponding command @samp{gdb_changed_register_list}. |
| 22405 | |
| 22406 | @subsubheading Example |
| 22407 | |
| 22408 | On a PPC MBX board: |
| 22409 | |
| 22410 | @smallexample |
| 22411 | (gdb) |
| 22412 | -exec-continue |
| 22413 | ^running |
| 22414 | |
| 22415 | (gdb) |
| 22416 | *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame=@{ |
| 22417 | func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c", |
| 22418 | line="5"@} |
| 22419 | (gdb) |
| 22420 | -data-list-changed-registers |
| 22421 | ^done,changed-registers=["0","1","2","4","5","6","7","8","9", |
| 22422 | "10","11","13","14","15","16","17","18","19","20","21","22","23", |
| 22423 | "24","25","26","27","28","30","31","64","65","66","67","69"] |
| 22424 | (gdb) |
| 22425 | @end smallexample |
| 22426 | |
| 22427 | |
| 22428 | @subheading The @code{-data-list-register-names} Command |
| 22429 | @findex -data-list-register-names |
| 22430 | |
| 22431 | @subsubheading Synopsis |
| 22432 | |
| 22433 | @smallexample |
| 22434 | -data-list-register-names [ ( @var{regno} )+ ] |
| 22435 | @end smallexample |
| 22436 | |
| 22437 | Show a list of register names for the current target. If no arguments |
| 22438 | are given, it shows a list of the names of all the registers. If |
| 22439 | integer numbers are given as arguments, it will print a list of the |
| 22440 | names of the registers corresponding to the arguments. To ensure |
| 22441 | consistency between a register name and its number, the output list may |
| 22442 | include empty register names. |
| 22443 | |
| 22444 | @subsubheading @value{GDBN} Command |
| 22445 | |
| 22446 | @value{GDBN} does not have a command which corresponds to |
| 22447 | @samp{-data-list-register-names}. In @code{gdbtk} there is a |
| 22448 | corresponding command @samp{gdb_regnames}. |
| 22449 | |
| 22450 | @subsubheading Example |
| 22451 | |
| 22452 | For the PPC MBX board: |
| 22453 | @smallexample |
| 22454 | (gdb) |
| 22455 | -data-list-register-names |
| 22456 | ^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7", |
| 22457 | "r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18", |
| 22458 | "r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29", |
| 22459 | "r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9", |
| 22460 | "f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20", |
| 22461 | "f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31", |
| 22462 | "", "pc","ps","cr","lr","ctr","xer"] |
| 22463 | (gdb) |
| 22464 | -data-list-register-names 1 2 3 |
| 22465 | ^done,register-names=["r1","r2","r3"] |
| 22466 | (gdb) |
| 22467 | @end smallexample |
| 22468 | |
| 22469 | @subheading The @code{-data-list-register-values} Command |
| 22470 | @findex -data-list-register-values |
| 22471 | |
| 22472 | @subsubheading Synopsis |
| 22473 | |
| 22474 | @smallexample |
| 22475 | -data-list-register-values @var{fmt} [ ( @var{regno} )*] |
| 22476 | @end smallexample |
| 22477 | |
| 22478 | Display the registers' contents. @var{fmt} is the format according to |
| 22479 | which the registers' contents are to be returned, followed by an optional |
| 22480 | list of numbers specifying the registers to display. A missing list of |
| 22481 | numbers indicates that the contents of all the registers must be returned. |
| 22482 | |
| 22483 | Allowed formats for @var{fmt} are: |
| 22484 | |
| 22485 | @table @code |
| 22486 | @item x |
| 22487 | Hexadecimal |
| 22488 | @item o |
| 22489 | Octal |
| 22490 | @item t |
| 22491 | Binary |
| 22492 | @item d |
| 22493 | Decimal |
| 22494 | @item r |
| 22495 | Raw |
| 22496 | @item N |
| 22497 | Natural |
| 22498 | @end table |
| 22499 | |
| 22500 | @subsubheading @value{GDBN} Command |
| 22501 | |
| 22502 | The corresponding @value{GDBN} commands are @samp{info reg}, @samp{info |
| 22503 | all-reg}, and (in @code{gdbtk}) @samp{gdb_fetch_registers}. |
| 22504 | |
| 22505 | @subsubheading Example |
| 22506 | |
| 22507 | For a PPC MBX board (note: line breaks are for readability only, they |
| 22508 | don't appear in the actual output): |
| 22509 | |
| 22510 | @smallexample |
| 22511 | (gdb) |
| 22512 | -data-list-register-values r 64 65 |
| 22513 | ^done,register-values=[@{number="64",value="0xfe00a300"@}, |
| 22514 | @{number="65",value="0x00029002"@}] |
| 22515 | (gdb) |
| 22516 | -data-list-register-values x |
| 22517 | ^done,register-values=[@{number="0",value="0xfe0043c8"@}, |
| 22518 | @{number="1",value="0x3fff88"@},@{number="2",value="0xfffffffe"@}, |
| 22519 | @{number="3",value="0x0"@},@{number="4",value="0xa"@}, |
| 22520 | @{number="5",value="0x3fff68"@},@{number="6",value="0x3fff58"@}, |
| 22521 | @{number="7",value="0xfe011e98"@},@{number="8",value="0x2"@}, |
| 22522 | @{number="9",value="0xfa202820"@},@{number="10",value="0xfa202808"@}, |
| 22523 | @{number="11",value="0x1"@},@{number="12",value="0x0"@}, |
| 22524 | @{number="13",value="0x4544"@},@{number="14",value="0xffdfffff"@}, |
| 22525 | @{number="15",value="0xffffffff"@},@{number="16",value="0xfffffeff"@}, |
| 22526 | @{number="17",value="0xefffffed"@},@{number="18",value="0xfffffffe"@}, |
| 22527 | @{number="19",value="0xffffffff"@},@{number="20",value="0xffffffff"@}, |
| 22528 | @{number="21",value="0xffffffff"@},@{number="22",value="0xfffffff7"@}, |
| 22529 | @{number="23",value="0xffffffff"@},@{number="24",value="0xffffffff"@}, |
| 22530 | @{number="25",value="0xffffffff"@},@{number="26",value="0xfffffffb"@}, |
| 22531 | @{number="27",value="0xffffffff"@},@{number="28",value="0xf7bfffff"@}, |
| 22532 | @{number="29",value="0x0"@},@{number="30",value="0xfe010000"@}, |
| 22533 | @{number="31",value="0x0"@},@{number="32",value="0x0"@}, |
| 22534 | @{number="33",value="0x0"@},@{number="34",value="0x0"@}, |
| 22535 | @{number="35",value="0x0"@},@{number="36",value="0x0"@}, |
| 22536 | @{number="37",value="0x0"@},@{number="38",value="0x0"@}, |
| 22537 | @{number="39",value="0x0"@},@{number="40",value="0x0"@}, |
| 22538 | @{number="41",value="0x0"@},@{number="42",value="0x0"@}, |
| 22539 | @{number="43",value="0x0"@},@{number="44",value="0x0"@}, |
| 22540 | @{number="45",value="0x0"@},@{number="46",value="0x0"@}, |
| 22541 | @{number="47",value="0x0"@},@{number="48",value="0x0"@}, |
| 22542 | @{number="49",value="0x0"@},@{number="50",value="0x0"@}, |
| 22543 | @{number="51",value="0x0"@},@{number="52",value="0x0"@}, |
| 22544 | @{number="53",value="0x0"@},@{number="54",value="0x0"@}, |
| 22545 | @{number="55",value="0x0"@},@{number="56",value="0x0"@}, |
| 22546 | @{number="57",value="0x0"@},@{number="58",value="0x0"@}, |
| 22547 | @{number="59",value="0x0"@},@{number="60",value="0x0"@}, |
| 22548 | @{number="61",value="0x0"@},@{number="62",value="0x0"@}, |
| 22549 | @{number="63",value="0x0"@},@{number="64",value="0xfe00a300"@}, |
| 22550 | @{number="65",value="0x29002"@},@{number="66",value="0x202f04b5"@}, |
| 22551 | @{number="67",value="0xfe0043b0"@},@{number="68",value="0xfe00b3e4"@}, |
| 22552 | @{number="69",value="0x20002b03"@}] |
| 22553 | (gdb) |
| 22554 | @end smallexample |
| 22555 | |
| 22556 | |
| 22557 | @subheading The @code{-data-read-memory} Command |
| 22558 | @findex -data-read-memory |
| 22559 | |
| 22560 | @subsubheading Synopsis |
| 22561 | |
| 22562 | @smallexample |
| 22563 | -data-read-memory [ -o @var{byte-offset} ] |
| 22564 | @var{address} @var{word-format} @var{word-size} |
| 22565 | @var{nr-rows} @var{nr-cols} [ @var{aschar} ] |
| 22566 | @end smallexample |
| 22567 | |
| 22568 | @noindent |
| 22569 | where: |
| 22570 | |
| 22571 | @table @samp |
| 22572 | @item @var{address} |
| 22573 | An expression specifying the address of the first memory word to be |
| 22574 | read. Complex expressions containing embedded white space should be |
| 22575 | quoted using the C convention. |
| 22576 | |
| 22577 | @item @var{word-format} |
| 22578 | The format to be used to print the memory words. The notation is the |
| 22579 | same as for @value{GDBN}'s @code{print} command (@pxref{Output Formats, |
| 22580 | ,Output Formats}). |
| 22581 | |
| 22582 | @item @var{word-size} |
| 22583 | The size of each memory word in bytes. |
| 22584 | |
| 22585 | @item @var{nr-rows} |
| 22586 | The number of rows in the output table. |
| 22587 | |
| 22588 | @item @var{nr-cols} |
| 22589 | The number of columns in the output table. |
| 22590 | |
| 22591 | @item @var{aschar} |
| 22592 | If present, indicates that each row should include an @sc{ascii} dump. The |
| 22593 | value of @var{aschar} is used as a padding character when a byte is not a |
| 22594 | member of the printable @sc{ascii} character set (printable @sc{ascii} |
| 22595 | characters are those whose code is between 32 and 126, inclusively). |
| 22596 | |
| 22597 | @item @var{byte-offset} |
| 22598 | An offset to add to the @var{address} before fetching memory. |
| 22599 | @end table |
| 22600 | |
| 22601 | This command displays memory contents as a table of @var{nr-rows} by |
| 22602 | @var{nr-cols} words, each word being @var{word-size} bytes. In total, |
| 22603 | @code{@var{nr-rows} * @var{nr-cols} * @var{word-size}} bytes are read |
| 22604 | (returned as @samp{total-bytes}). Should less than the requested number |
| 22605 | of bytes be returned by the target, the missing words are identified |
| 22606 | using @samp{N/A}. The number of bytes read from the target is returned |
| 22607 | in @samp{nr-bytes} and the starting address used to read memory in |
| 22608 | @samp{addr}. |
| 22609 | |
| 22610 | The address of the next/previous row or page is available in |
| 22611 | @samp{next-row} and @samp{prev-row}, @samp{next-page} and |
| 22612 | @samp{prev-page}. |
| 22613 | |
| 22614 | @subsubheading @value{GDBN} Command |
| 22615 | |
| 22616 | The corresponding @value{GDBN} command is @samp{x}. @code{gdbtk} has |
| 22617 | @samp{gdb_get_mem} memory read command. |
| 22618 | |
| 22619 | @subsubheading Example |
| 22620 | |
| 22621 | Read six bytes of memory starting at @code{bytes+6} but then offset by |
| 22622 | @code{-6} bytes. Format as three rows of two columns. One byte per |
| 22623 | word. Display each word in hex. |
| 22624 | |
| 22625 | @smallexample |
| 22626 | (gdb) |
| 22627 | 9-data-read-memory -o -6 -- bytes+6 x 1 3 2 |
| 22628 | 9^done,addr="0x00001390",nr-bytes="6",total-bytes="6", |
| 22629 | next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396", |
| 22630 | prev-page="0x0000138a",memory=[ |
| 22631 | @{addr="0x00001390",data=["0x00","0x01"]@}, |
| 22632 | @{addr="0x00001392",data=["0x02","0x03"]@}, |
| 22633 | @{addr="0x00001394",data=["0x04","0x05"]@}] |
| 22634 | (gdb) |
| 22635 | @end smallexample |
| 22636 | |
| 22637 | Read two bytes of memory starting at address @code{shorts + 64} and |
| 22638 | display as a single word formatted in decimal. |
| 22639 | |
| 22640 | @smallexample |
| 22641 | (gdb) |
| 22642 | 5-data-read-memory shorts+64 d 2 1 1 |
| 22643 | 5^done,addr="0x00001510",nr-bytes="2",total-bytes="2", |
| 22644 | next-row="0x00001512",prev-row="0x0000150e", |
| 22645 | next-page="0x00001512",prev-page="0x0000150e",memory=[ |
| 22646 | @{addr="0x00001510",data=["128"]@}] |
| 22647 | (gdb) |
| 22648 | @end smallexample |
| 22649 | |
| 22650 | Read thirty two bytes of memory starting at @code{bytes+16} and format |
| 22651 | as eight rows of four columns. Include a string encoding with @samp{x} |
| 22652 | used as the non-printable character. |
| 22653 | |
| 22654 | @smallexample |
| 22655 | (gdb) |
| 22656 | 4-data-read-memory bytes+16 x 1 8 4 x |
| 22657 | 4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32", |
| 22658 | next-row="0x000013c0",prev-row="0x0000139c", |
| 22659 | next-page="0x000013c0",prev-page="0x00001380",memory=[ |
| 22660 | @{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"@}, |
| 22661 | @{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"@}, |
| 22662 | @{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"@}, |
| 22663 | @{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"@}, |
| 22664 | @{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"@}, |
| 22665 | @{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"@}, |
| 22666 | @{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"@}, |
| 22667 | @{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"@}] |
| 22668 | (gdb) |
| 22669 | @end smallexample |
| 22670 | |
| 22671 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 22672 | @node GDB/MI Tracepoint Commands |
| 22673 | @section @sc{gdb/mi} Tracepoint Commands |
| 22674 | |
| 22675 | The tracepoint commands are not yet implemented. |
| 22676 | |
| 22677 | @c @subheading -trace-actions |
| 22678 | |
| 22679 | @c @subheading -trace-delete |
| 22680 | |
| 22681 | @c @subheading -trace-disable |
| 22682 | |
| 22683 | @c @subheading -trace-dump |
| 22684 | |
| 22685 | @c @subheading -trace-enable |
| 22686 | |
| 22687 | @c @subheading -trace-exists |
| 22688 | |
| 22689 | @c @subheading -trace-find |
| 22690 | |
| 22691 | @c @subheading -trace-frame-number |
| 22692 | |
| 22693 | @c @subheading -trace-info |
| 22694 | |
| 22695 | @c @subheading -trace-insert |
| 22696 | |
| 22697 | @c @subheading -trace-list |
| 22698 | |
| 22699 | @c @subheading -trace-pass-count |
| 22700 | |
| 22701 | @c @subheading -trace-save |
| 22702 | |
| 22703 | @c @subheading -trace-start |
| 22704 | |
| 22705 | @c @subheading -trace-stop |
| 22706 | |
| 22707 | |
| 22708 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 22709 | @node GDB/MI Symbol Query |
| 22710 | @section @sc{gdb/mi} Symbol Query Commands |
| 22711 | |
| 22712 | |
| 22713 | @subheading The @code{-symbol-info-address} Command |
| 22714 | @findex -symbol-info-address |
| 22715 | |
| 22716 | @subsubheading Synopsis |
| 22717 | |
| 22718 | @smallexample |
| 22719 | -symbol-info-address @var{symbol} |
| 22720 | @end smallexample |
| 22721 | |
| 22722 | Describe where @var{symbol} is stored. |
| 22723 | |
| 22724 | @subsubheading @value{GDBN} Command |
| 22725 | |
| 22726 | The corresponding @value{GDBN} command is @samp{info address}. |
| 22727 | |
| 22728 | @subsubheading Example |
| 22729 | N.A. |
| 22730 | |
| 22731 | |
| 22732 | @subheading The @code{-symbol-info-file} Command |
| 22733 | @findex -symbol-info-file |
| 22734 | |
| 22735 | @subsubheading Synopsis |
| 22736 | |
| 22737 | @smallexample |
| 22738 | -symbol-info-file |
| 22739 | @end smallexample |
| 22740 | |
| 22741 | Show the file for the symbol. |
| 22742 | |
| 22743 | @subsubheading @value{GDBN} Command |
| 22744 | |
| 22745 | There's no equivalent @value{GDBN} command. @code{gdbtk} has |
| 22746 | @samp{gdb_find_file}. |
| 22747 | |
| 22748 | @subsubheading Example |
| 22749 | N.A. |
| 22750 | |
| 22751 | |
| 22752 | @subheading The @code{-symbol-info-function} Command |
| 22753 | @findex -symbol-info-function |
| 22754 | |
| 22755 | @subsubheading Synopsis |
| 22756 | |
| 22757 | @smallexample |
| 22758 | -symbol-info-function |
| 22759 | @end smallexample |
| 22760 | |
| 22761 | Show which function the symbol lives in. |
| 22762 | |
| 22763 | @subsubheading @value{GDBN} Command |
| 22764 | |
| 22765 | @samp{gdb_get_function} in @code{gdbtk}. |
| 22766 | |
| 22767 | @subsubheading Example |
| 22768 | N.A. |
| 22769 | |
| 22770 | |
| 22771 | @subheading The @code{-symbol-info-line} Command |
| 22772 | @findex -symbol-info-line |
| 22773 | |
| 22774 | @subsubheading Synopsis |
| 22775 | |
| 22776 | @smallexample |
| 22777 | -symbol-info-line |
| 22778 | @end smallexample |
| 22779 | |
| 22780 | Show the core addresses of the code for a source line. |
| 22781 | |
| 22782 | @subsubheading @value{GDBN} Command |
| 22783 | |
| 22784 | The corresponding @value{GDBN} command is @samp{info line}. |
| 22785 | @code{gdbtk} has the @samp{gdb_get_line} and @samp{gdb_get_file} commands. |
| 22786 | |
| 22787 | @subsubheading Example |
| 22788 | N.A. |
| 22789 | |
| 22790 | |
| 22791 | @subheading The @code{-symbol-info-symbol} Command |
| 22792 | @findex -symbol-info-symbol |
| 22793 | |
| 22794 | @subsubheading Synopsis |
| 22795 | |
| 22796 | @smallexample |
| 22797 | -symbol-info-symbol @var{addr} |
| 22798 | @end smallexample |
| 22799 | |
| 22800 | Describe what symbol is at location @var{addr}. |
| 22801 | |
| 22802 | @subsubheading @value{GDBN} Command |
| 22803 | |
| 22804 | The corresponding @value{GDBN} command is @samp{info symbol}. |
| 22805 | |
| 22806 | @subsubheading Example |
| 22807 | N.A. |
| 22808 | |
| 22809 | |
| 22810 | @subheading The @code{-symbol-list-functions} Command |
| 22811 | @findex -symbol-list-functions |
| 22812 | |
| 22813 | @subsubheading Synopsis |
| 22814 | |
| 22815 | @smallexample |
| 22816 | -symbol-list-functions |
| 22817 | @end smallexample |
| 22818 | |
| 22819 | List the functions in the executable. |
| 22820 | |
| 22821 | @subsubheading @value{GDBN} Command |
| 22822 | |
| 22823 | @samp{info functions} in @value{GDBN}, @samp{gdb_listfunc} and |
| 22824 | @samp{gdb_search} in @code{gdbtk}. |
| 22825 | |
| 22826 | @subsubheading Example |
| 22827 | N.A. |
| 22828 | |
| 22829 | |
| 22830 | @subheading The @code{-symbol-list-lines} Command |
| 22831 | @findex -symbol-list-lines |
| 22832 | |
| 22833 | @subsubheading Synopsis |
| 22834 | |
| 22835 | @smallexample |
| 22836 | -symbol-list-lines @var{filename} |
| 22837 | @end smallexample |
| 22838 | |
| 22839 | Print the list of lines that contain code and their associated program |
| 22840 | addresses for the given source filename. The entries are sorted in |
| 22841 | ascending PC order. |
| 22842 | |
| 22843 | @subsubheading @value{GDBN} Command |
| 22844 | |
| 22845 | There is no corresponding @value{GDBN} command. |
| 22846 | |
| 22847 | @subsubheading Example |
| 22848 | @smallexample |
| 22849 | (gdb) |
| 22850 | -symbol-list-lines basics.c |
| 22851 | ^done,lines=[@{pc="0x08048554",line="7"@},@{pc="0x0804855a",line="8"@}] |
| 22852 | (gdb) |
| 22853 | @end smallexample |
| 22854 | |
| 22855 | |
| 22856 | @subheading The @code{-symbol-list-types} Command |
| 22857 | @findex -symbol-list-types |
| 22858 | |
| 22859 | @subsubheading Synopsis |
| 22860 | |
| 22861 | @smallexample |
| 22862 | -symbol-list-types |
| 22863 | @end smallexample |
| 22864 | |
| 22865 | List all the type names. |
| 22866 | |
| 22867 | @subsubheading @value{GDBN} Command |
| 22868 | |
| 22869 | The corresponding commands are @samp{info types} in @value{GDBN}, |
| 22870 | @samp{gdb_search} in @code{gdbtk}. |
| 22871 | |
| 22872 | @subsubheading Example |
| 22873 | N.A. |
| 22874 | |
| 22875 | |
| 22876 | @subheading The @code{-symbol-list-variables} Command |
| 22877 | @findex -symbol-list-variables |
| 22878 | |
| 22879 | @subsubheading Synopsis |
| 22880 | |
| 22881 | @smallexample |
| 22882 | -symbol-list-variables |
| 22883 | @end smallexample |
| 22884 | |
| 22885 | List all the global and static variable names. |
| 22886 | |
| 22887 | @subsubheading @value{GDBN} Command |
| 22888 | |
| 22889 | @samp{info variables} in @value{GDBN}, @samp{gdb_search} in @code{gdbtk}. |
| 22890 | |
| 22891 | @subsubheading Example |
| 22892 | N.A. |
| 22893 | |
| 22894 | |
| 22895 | @subheading The @code{-symbol-locate} Command |
| 22896 | @findex -symbol-locate |
| 22897 | |
| 22898 | @subsubheading Synopsis |
| 22899 | |
| 22900 | @smallexample |
| 22901 | -symbol-locate |
| 22902 | @end smallexample |
| 22903 | |
| 22904 | @subsubheading @value{GDBN} Command |
| 22905 | |
| 22906 | @samp{gdb_loc} in @code{gdbtk}. |
| 22907 | |
| 22908 | @subsubheading Example |
| 22909 | N.A. |
| 22910 | |
| 22911 | |
| 22912 | @subheading The @code{-symbol-type} Command |
| 22913 | @findex -symbol-type |
| 22914 | |
| 22915 | @subsubheading Synopsis |
| 22916 | |
| 22917 | @smallexample |
| 22918 | -symbol-type @var{variable} |
| 22919 | @end smallexample |
| 22920 | |
| 22921 | Show type of @var{variable}. |
| 22922 | |
| 22923 | @subsubheading @value{GDBN} Command |
| 22924 | |
| 22925 | The corresponding @value{GDBN} command is @samp{ptype}, @code{gdbtk} has |
| 22926 | @samp{gdb_obj_variable}. |
| 22927 | |
| 22928 | @subsubheading Example |
| 22929 | N.A. |
| 22930 | |
| 22931 | |
| 22932 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 22933 | @node GDB/MI File Commands |
| 22934 | @section @sc{gdb/mi} File Commands |
| 22935 | |
| 22936 | This section describes the GDB/MI commands to specify executable file names |
| 22937 | and to read in and obtain symbol table information. |
| 22938 | |
| 22939 | @subheading The @code{-file-exec-and-symbols} Command |
| 22940 | @findex -file-exec-and-symbols |
| 22941 | |
| 22942 | @subsubheading Synopsis |
| 22943 | |
| 22944 | @smallexample |
| 22945 | -file-exec-and-symbols @var{file} |
| 22946 | @end smallexample |
| 22947 | |
| 22948 | Specify the executable file to be debugged. This file is the one from |
| 22949 | which the symbol table is also read. If no file is specified, the |
| 22950 | command clears the executable and symbol information. If breakpoints |
| 22951 | are set when using this command with no arguments, @value{GDBN} will produce |
| 22952 | error messages. Otherwise, no output is produced, except a completion |
| 22953 | notification. |
| 22954 | |
| 22955 | @subsubheading @value{GDBN} Command |
| 22956 | |
| 22957 | The corresponding @value{GDBN} command is @samp{file}. |
| 22958 | |
| 22959 | @subsubheading Example |
| 22960 | |
| 22961 | @smallexample |
| 22962 | (gdb) |
| 22963 | -file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx |
| 22964 | ^done |
| 22965 | (gdb) |
| 22966 | @end smallexample |
| 22967 | |
| 22968 | |
| 22969 | @subheading The @code{-file-exec-file} Command |
| 22970 | @findex -file-exec-file |
| 22971 | |
| 22972 | @subsubheading Synopsis |
| 22973 | |
| 22974 | @smallexample |
| 22975 | -file-exec-file @var{file} |
| 22976 | @end smallexample |
| 22977 | |
| 22978 | Specify the executable file to be debugged. Unlike |
| 22979 | @samp{-file-exec-and-symbols}, the symbol table is @emph{not} read |
| 22980 | from this file. If used without argument, @value{GDBN} clears the information |
| 22981 | about the executable file. No output is produced, except a completion |
| 22982 | notification. |
| 22983 | |
| 22984 | @subsubheading @value{GDBN} Command |
| 22985 | |
| 22986 | The corresponding @value{GDBN} command is @samp{exec-file}. |
| 22987 | |
| 22988 | @subsubheading Example |
| 22989 | |
| 22990 | @smallexample |
| 22991 | (gdb) |
| 22992 | -file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx |
| 22993 | ^done |
| 22994 | (gdb) |
| 22995 | @end smallexample |
| 22996 | |
| 22997 | |
| 22998 | @subheading The @code{-file-list-exec-sections} Command |
| 22999 | @findex -file-list-exec-sections |
| 23000 | |
| 23001 | @subsubheading Synopsis |
| 23002 | |
| 23003 | @smallexample |
| 23004 | -file-list-exec-sections |
| 23005 | @end smallexample |
| 23006 | |
| 23007 | List the sections of the current executable file. |
| 23008 | |
| 23009 | @subsubheading @value{GDBN} Command |
| 23010 | |
| 23011 | The @value{GDBN} command @samp{info file} shows, among the rest, the same |
| 23012 | information as this command. @code{gdbtk} has a corresponding command |
| 23013 | @samp{gdb_load_info}. |
| 23014 | |
| 23015 | @subsubheading Example |
| 23016 | N.A. |
| 23017 | |
| 23018 | |
| 23019 | @subheading The @code{-file-list-exec-source-file} Command |
| 23020 | @findex -file-list-exec-source-file |
| 23021 | |
| 23022 | @subsubheading Synopsis |
| 23023 | |
| 23024 | @smallexample |
| 23025 | -file-list-exec-source-file |
| 23026 | @end smallexample |
| 23027 | |
| 23028 | List the line number, the current source file, and the absolute path |
| 23029 | to the current source file for the current executable. The macro |
| 23030 | information field has a value of @samp{1} or @samp{0} depending on |
| 23031 | whether or not the file includes preprocessor macro information. |
| 23032 | |
| 23033 | @subsubheading @value{GDBN} Command |
| 23034 | |
| 23035 | The @value{GDBN} equivalent is @samp{info source} |
| 23036 | |
| 23037 | @subsubheading Example |
| 23038 | |
| 23039 | @smallexample |
| 23040 | (gdb) |
| 23041 | 123-file-list-exec-source-file |
| 23042 | 123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1" |
| 23043 | (gdb) |
| 23044 | @end smallexample |
| 23045 | |
| 23046 | |
| 23047 | @subheading The @code{-file-list-exec-source-files} Command |
| 23048 | @findex -file-list-exec-source-files |
| 23049 | |
| 23050 | @subsubheading Synopsis |
| 23051 | |
| 23052 | @smallexample |
| 23053 | -file-list-exec-source-files |
| 23054 | @end smallexample |
| 23055 | |
| 23056 | List the source files for the current executable. |
| 23057 | |
| 23058 | It will always output the filename, but only when @value{GDBN} can find |
| 23059 | the absolute file name of a source file, will it output the fullname. |
| 23060 | |
| 23061 | @subsubheading @value{GDBN} Command |
| 23062 | |
| 23063 | The @value{GDBN} equivalent is @samp{info sources}. |
| 23064 | @code{gdbtk} has an analogous command @samp{gdb_listfiles}. |
| 23065 | |
| 23066 | @subsubheading Example |
| 23067 | @smallexample |
| 23068 | (gdb) |
| 23069 | -file-list-exec-source-files |
| 23070 | ^done,files=[ |
| 23071 | @{file=foo.c,fullname=/home/foo.c@}, |
| 23072 | @{file=/home/bar.c,fullname=/home/bar.c@}, |
| 23073 | @{file=gdb_could_not_find_fullpath.c@}] |
| 23074 | (gdb) |
| 23075 | @end smallexample |
| 23076 | |
| 23077 | @subheading The @code{-file-list-shared-libraries} Command |
| 23078 | @findex -file-list-shared-libraries |
| 23079 | |
| 23080 | @subsubheading Synopsis |
| 23081 | |
| 23082 | @smallexample |
| 23083 | -file-list-shared-libraries |
| 23084 | @end smallexample |
| 23085 | |
| 23086 | List the shared libraries in the program. |
| 23087 | |
| 23088 | @subsubheading @value{GDBN} Command |
| 23089 | |
| 23090 | The corresponding @value{GDBN} command is @samp{info shared}. |
| 23091 | |
| 23092 | @subsubheading Example |
| 23093 | N.A. |
| 23094 | |
| 23095 | |
| 23096 | @subheading The @code{-file-list-symbol-files} Command |
| 23097 | @findex -file-list-symbol-files |
| 23098 | |
| 23099 | @subsubheading Synopsis |
| 23100 | |
| 23101 | @smallexample |
| 23102 | -file-list-symbol-files |
| 23103 | @end smallexample |
| 23104 | |
| 23105 | List symbol files. |
| 23106 | |
| 23107 | @subsubheading @value{GDBN} Command |
| 23108 | |
| 23109 | The corresponding @value{GDBN} command is @samp{info file} (part of it). |
| 23110 | |
| 23111 | @subsubheading Example |
| 23112 | N.A. |
| 23113 | |
| 23114 | |
| 23115 | @subheading The @code{-file-symbol-file} Command |
| 23116 | @findex -file-symbol-file |
| 23117 | |
| 23118 | @subsubheading Synopsis |
| 23119 | |
| 23120 | @smallexample |
| 23121 | -file-symbol-file @var{file} |
| 23122 | @end smallexample |
| 23123 | |
| 23124 | Read symbol table info from the specified @var{file} argument. When |
| 23125 | used without arguments, clears @value{GDBN}'s symbol table info. No output is |
| 23126 | produced, except for a completion notification. |
| 23127 | |
| 23128 | @subsubheading @value{GDBN} Command |
| 23129 | |
| 23130 | The corresponding @value{GDBN} command is @samp{symbol-file}. |
| 23131 | |
| 23132 | @subsubheading Example |
| 23133 | |
| 23134 | @smallexample |
| 23135 | (gdb) |
| 23136 | -file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx |
| 23137 | ^done |
| 23138 | (gdb) |
| 23139 | @end smallexample |
| 23140 | |
| 23141 | @ignore |
| 23142 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 23143 | @node GDB/MI Memory Overlay Commands |
| 23144 | @section @sc{gdb/mi} Memory Overlay Commands |
| 23145 | |
| 23146 | The memory overlay commands are not implemented. |
| 23147 | |
| 23148 | @c @subheading -overlay-auto |
| 23149 | |
| 23150 | @c @subheading -overlay-list-mapping-state |
| 23151 | |
| 23152 | @c @subheading -overlay-list-overlays |
| 23153 | |
| 23154 | @c @subheading -overlay-map |
| 23155 | |
| 23156 | @c @subheading -overlay-off |
| 23157 | |
| 23158 | @c @subheading -overlay-on |
| 23159 | |
| 23160 | @c @subheading -overlay-unmap |
| 23161 | |
| 23162 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 23163 | @node GDB/MI Signal Handling Commands |
| 23164 | @section @sc{gdb/mi} Signal Handling Commands |
| 23165 | |
| 23166 | Signal handling commands are not implemented. |
| 23167 | |
| 23168 | @c @subheading -signal-handle |
| 23169 | |
| 23170 | @c @subheading -signal-list-handle-actions |
| 23171 | |
| 23172 | @c @subheading -signal-list-signal-types |
| 23173 | @end ignore |
| 23174 | |
| 23175 | |
| 23176 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 23177 | @node GDB/MI Target Manipulation |
| 23178 | @section @sc{gdb/mi} Target Manipulation Commands |
| 23179 | |
| 23180 | |
| 23181 | @subheading The @code{-target-attach} Command |
| 23182 | @findex -target-attach |
| 23183 | |
| 23184 | @subsubheading Synopsis |
| 23185 | |
| 23186 | @smallexample |
| 23187 | -target-attach @var{pid} | @var{gid} | @var{file} |
| 23188 | @end smallexample |
| 23189 | |
| 23190 | Attach to a process @var{pid} or a file @var{file} outside of |
| 23191 | @value{GDBN}, or a thread group @var{gid}. If attaching to a thread |
| 23192 | group, the id previously returned by |
| 23193 | @samp{-list-thread-groups --available} must be used. |
| 23194 | |
| 23195 | @subsubheading @value{GDBN} Command |
| 23196 | |
| 23197 | The corresponding @value{GDBN} command is @samp{attach}. |
| 23198 | |
| 23199 | @subsubheading Example |
| 23200 | @smallexample |
| 23201 | (gdb) |
| 23202 | -target-attach 34 |
| 23203 | =thread-created,id="1" |
| 23204 | *stopped,thread-id="1",frame=@{addr="0xb7f7e410",func="bar",args=[]@} |
| 23205 | ^done |
| 23206 | (gdb) |
| 23207 | @end smallexample |
| 23208 | |
| 23209 | @subheading The @code{-target-compare-sections} Command |
| 23210 | @findex -target-compare-sections |
| 23211 | |
| 23212 | @subsubheading Synopsis |
| 23213 | |
| 23214 | @smallexample |
| 23215 | -target-compare-sections [ @var{section} ] |
| 23216 | @end smallexample |
| 23217 | |
| 23218 | Compare data of section @var{section} on target to the exec file. |
| 23219 | Without the argument, all sections are compared. |
| 23220 | |
| 23221 | @subsubheading @value{GDBN} Command |
| 23222 | |
| 23223 | The @value{GDBN} equivalent is @samp{compare-sections}. |
| 23224 | |
| 23225 | @subsubheading Example |
| 23226 | N.A. |
| 23227 | |
| 23228 | |
| 23229 | @subheading The @code{-target-detach} Command |
| 23230 | @findex -target-detach |
| 23231 | |
| 23232 | @subsubheading Synopsis |
| 23233 | |
| 23234 | @smallexample |
| 23235 | -target-detach [ @var{pid} | @var{gid} ] |
| 23236 | @end smallexample |
| 23237 | |
| 23238 | Detach from the remote target which normally resumes its execution. |
| 23239 | If either @var{pid} or @var{gid} is specified, detaches from either |
| 23240 | the specified process, or specified thread group. There's no output. |
| 23241 | |
| 23242 | @subsubheading @value{GDBN} Command |
| 23243 | |
| 23244 | The corresponding @value{GDBN} command is @samp{detach}. |
| 23245 | |
| 23246 | @subsubheading Example |
| 23247 | |
| 23248 | @smallexample |
| 23249 | (gdb) |
| 23250 | -target-detach |
| 23251 | ^done |
| 23252 | (gdb) |
| 23253 | @end smallexample |
| 23254 | |
| 23255 | |
| 23256 | @subheading The @code{-target-disconnect} Command |
| 23257 | @findex -target-disconnect |
| 23258 | |
| 23259 | @subsubheading Synopsis |
| 23260 | |
| 23261 | @smallexample |
| 23262 | -target-disconnect |
| 23263 | @end smallexample |
| 23264 | |
| 23265 | Disconnect from the remote target. There's no output and the target is |
| 23266 | generally not resumed. |
| 23267 | |
| 23268 | @subsubheading @value{GDBN} Command |
| 23269 | |
| 23270 | The corresponding @value{GDBN} command is @samp{disconnect}. |
| 23271 | |
| 23272 | @subsubheading Example |
| 23273 | |
| 23274 | @smallexample |
| 23275 | (gdb) |
| 23276 | -target-disconnect |
| 23277 | ^done |
| 23278 | (gdb) |
| 23279 | @end smallexample |
| 23280 | |
| 23281 | |
| 23282 | @subheading The @code{-target-download} Command |
| 23283 | @findex -target-download |
| 23284 | |
| 23285 | @subsubheading Synopsis |
| 23286 | |
| 23287 | @smallexample |
| 23288 | -target-download |
| 23289 | @end smallexample |
| 23290 | |
| 23291 | Loads the executable onto the remote target. |
| 23292 | It prints out an update message every half second, which includes the fields: |
| 23293 | |
| 23294 | @table @samp |
| 23295 | @item section |
| 23296 | The name of the section. |
| 23297 | @item section-sent |
| 23298 | The size of what has been sent so far for that section. |
| 23299 | @item section-size |
| 23300 | The size of the section. |
| 23301 | @item total-sent |
| 23302 | The total size of what was sent so far (the current and the previous sections). |
| 23303 | @item total-size |
| 23304 | The size of the overall executable to download. |
| 23305 | @end table |
| 23306 | |
| 23307 | @noindent |
| 23308 | Each message is sent as status record (@pxref{GDB/MI Output Syntax, , |
| 23309 | @sc{gdb/mi} Output Syntax}). |
| 23310 | |
| 23311 | In addition, it prints the name and size of the sections, as they are |
| 23312 | downloaded. These messages include the following fields: |
| 23313 | |
| 23314 | @table @samp |
| 23315 | @item section |
| 23316 | The name of the section. |
| 23317 | @item section-size |
| 23318 | The size of the section. |
| 23319 | @item total-size |
| 23320 | The size of the overall executable to download. |
| 23321 | @end table |
| 23322 | |
| 23323 | @noindent |
| 23324 | At the end, a summary is printed. |
| 23325 | |
| 23326 | @subsubheading @value{GDBN} Command |
| 23327 | |
| 23328 | The corresponding @value{GDBN} command is @samp{load}. |
| 23329 | |
| 23330 | @subsubheading Example |
| 23331 | |
| 23332 | Note: each status message appears on a single line. Here the messages |
| 23333 | have been broken down so that they can fit onto a page. |
| 23334 | |
| 23335 | @smallexample |
| 23336 | (gdb) |
| 23337 | -target-download |
| 23338 | +download,@{section=".text",section-size="6668",total-size="9880"@} |
| 23339 | +download,@{section=".text",section-sent="512",section-size="6668", |
| 23340 | total-sent="512",total-size="9880"@} |
| 23341 | +download,@{section=".text",section-sent="1024",section-size="6668", |
| 23342 | total-sent="1024",total-size="9880"@} |
| 23343 | +download,@{section=".text",section-sent="1536",section-size="6668", |
| 23344 | total-sent="1536",total-size="9880"@} |
| 23345 | +download,@{section=".text",section-sent="2048",section-size="6668", |
| 23346 | total-sent="2048",total-size="9880"@} |
| 23347 | +download,@{section=".text",section-sent="2560",section-size="6668", |
| 23348 | total-sent="2560",total-size="9880"@} |
| 23349 | +download,@{section=".text",section-sent="3072",section-size="6668", |
| 23350 | total-sent="3072",total-size="9880"@} |
| 23351 | +download,@{section=".text",section-sent="3584",section-size="6668", |
| 23352 | total-sent="3584",total-size="9880"@} |
| 23353 | +download,@{section=".text",section-sent="4096",section-size="6668", |
| 23354 | total-sent="4096",total-size="9880"@} |
| 23355 | +download,@{section=".text",section-sent="4608",section-size="6668", |
| 23356 | total-sent="4608",total-size="9880"@} |
| 23357 | +download,@{section=".text",section-sent="5120",section-size="6668", |
| 23358 | total-sent="5120",total-size="9880"@} |
| 23359 | +download,@{section=".text",section-sent="5632",section-size="6668", |
| 23360 | total-sent="5632",total-size="9880"@} |
| 23361 | +download,@{section=".text",section-sent="6144",section-size="6668", |
| 23362 | total-sent="6144",total-size="9880"@} |
| 23363 | +download,@{section=".text",section-sent="6656",section-size="6668", |
| 23364 | total-sent="6656",total-size="9880"@} |
| 23365 | +download,@{section=".init",section-size="28",total-size="9880"@} |
| 23366 | +download,@{section=".fini",section-size="28",total-size="9880"@} |
| 23367 | +download,@{section=".data",section-size="3156",total-size="9880"@} |
| 23368 | +download,@{section=".data",section-sent="512",section-size="3156", |
| 23369 | total-sent="7236",total-size="9880"@} |
| 23370 | +download,@{section=".data",section-sent="1024",section-size="3156", |
| 23371 | total-sent="7748",total-size="9880"@} |
| 23372 | +download,@{section=".data",section-sent="1536",section-size="3156", |
| 23373 | total-sent="8260",total-size="9880"@} |
| 23374 | +download,@{section=".data",section-sent="2048",section-size="3156", |
| 23375 | total-sent="8772",total-size="9880"@} |
| 23376 | +download,@{section=".data",section-sent="2560",section-size="3156", |
| 23377 | total-sent="9284",total-size="9880"@} |
| 23378 | +download,@{section=".data",section-sent="3072",section-size="3156", |
| 23379 | total-sent="9796",total-size="9880"@} |
| 23380 | ^done,address="0x10004",load-size="9880",transfer-rate="6586", |
| 23381 | write-rate="429" |
| 23382 | (gdb) |
| 23383 | @end smallexample |
| 23384 | |
| 23385 | |
| 23386 | @subheading The @code{-target-exec-status} Command |
| 23387 | @findex -target-exec-status |
| 23388 | |
| 23389 | @subsubheading Synopsis |
| 23390 | |
| 23391 | @smallexample |
| 23392 | -target-exec-status |
| 23393 | @end smallexample |
| 23394 | |
| 23395 | Provide information on the state of the target (whether it is running or |
| 23396 | not, for instance). |
| 23397 | |
| 23398 | @subsubheading @value{GDBN} Command |
| 23399 | |
| 23400 | There's no equivalent @value{GDBN} command. |
| 23401 | |
| 23402 | @subsubheading Example |
| 23403 | N.A. |
| 23404 | |
| 23405 | |
| 23406 | @subheading The @code{-target-list-available-targets} Command |
| 23407 | @findex -target-list-available-targets |
| 23408 | |
| 23409 | @subsubheading Synopsis |
| 23410 | |
| 23411 | @smallexample |
| 23412 | -target-list-available-targets |
| 23413 | @end smallexample |
| 23414 | |
| 23415 | List the possible targets to connect to. |
| 23416 | |
| 23417 | @subsubheading @value{GDBN} Command |
| 23418 | |
| 23419 | The corresponding @value{GDBN} command is @samp{help target}. |
| 23420 | |
| 23421 | @subsubheading Example |
| 23422 | N.A. |
| 23423 | |
| 23424 | |
| 23425 | @subheading The @code{-target-list-current-targets} Command |
| 23426 | @findex -target-list-current-targets |
| 23427 | |
| 23428 | @subsubheading Synopsis |
| 23429 | |
| 23430 | @smallexample |
| 23431 | -target-list-current-targets |
| 23432 | @end smallexample |
| 23433 | |
| 23434 | Describe the current target. |
| 23435 | |
| 23436 | @subsubheading @value{GDBN} Command |
| 23437 | |
| 23438 | The corresponding information is printed by @samp{info file} (among |
| 23439 | other things). |
| 23440 | |
| 23441 | @subsubheading Example |
| 23442 | N.A. |
| 23443 | |
| 23444 | |
| 23445 | @subheading The @code{-target-list-parameters} Command |
| 23446 | @findex -target-list-parameters |
| 23447 | |
| 23448 | @subsubheading Synopsis |
| 23449 | |
| 23450 | @smallexample |
| 23451 | -target-list-parameters |
| 23452 | @end smallexample |
| 23453 | |
| 23454 | @c ???? |
| 23455 | |
| 23456 | @subsubheading @value{GDBN} Command |
| 23457 | |
| 23458 | No equivalent. |
| 23459 | |
| 23460 | @subsubheading Example |
| 23461 | N.A. |
| 23462 | |
| 23463 | |
| 23464 | @subheading The @code{-target-select} Command |
| 23465 | @findex -target-select |
| 23466 | |
| 23467 | @subsubheading Synopsis |
| 23468 | |
| 23469 | @smallexample |
| 23470 | -target-select @var{type} @var{parameters @dots{}} |
| 23471 | @end smallexample |
| 23472 | |
| 23473 | Connect @value{GDBN} to the remote target. This command takes two args: |
| 23474 | |
| 23475 | @table @samp |
| 23476 | @item @var{type} |
| 23477 | The type of target, for instance @samp{remote}, etc. |
| 23478 | @item @var{parameters} |
| 23479 | Device names, host names and the like. @xref{Target Commands, , |
| 23480 | Commands for Managing Targets}, for more details. |
| 23481 | @end table |
| 23482 | |
| 23483 | The output is a connection notification, followed by the address at |
| 23484 | which the target program is, in the following form: |
| 23485 | |
| 23486 | @smallexample |
| 23487 | ^connected,addr="@var{address}",func="@var{function name}", |
| 23488 | args=[@var{arg list}] |
| 23489 | @end smallexample |
| 23490 | |
| 23491 | @subsubheading @value{GDBN} Command |
| 23492 | |
| 23493 | The corresponding @value{GDBN} command is @samp{target}. |
| 23494 | |
| 23495 | @subsubheading Example |
| 23496 | |
| 23497 | @smallexample |
| 23498 | (gdb) |
| 23499 | -target-select remote /dev/ttya |
| 23500 | ^connected,addr="0xfe00a300",func="??",args=[] |
| 23501 | (gdb) |
| 23502 | @end smallexample |
| 23503 | |
| 23504 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 23505 | @node GDB/MI File Transfer Commands |
| 23506 | @section @sc{gdb/mi} File Transfer Commands |
| 23507 | |
| 23508 | |
| 23509 | @subheading The @code{-target-file-put} Command |
| 23510 | @findex -target-file-put |
| 23511 | |
| 23512 | @subsubheading Synopsis |
| 23513 | |
| 23514 | @smallexample |
| 23515 | -target-file-put @var{hostfile} @var{targetfile} |
| 23516 | @end smallexample |
| 23517 | |
| 23518 | Copy file @var{hostfile} from the host system (the machine running |
| 23519 | @value{GDBN}) to @var{targetfile} on the target system. |
| 23520 | |
| 23521 | @subsubheading @value{GDBN} Command |
| 23522 | |
| 23523 | The corresponding @value{GDBN} command is @samp{remote put}. |
| 23524 | |
| 23525 | @subsubheading Example |
| 23526 | |
| 23527 | @smallexample |
| 23528 | (gdb) |
| 23529 | -target-file-put localfile remotefile |
| 23530 | ^done |
| 23531 | (gdb) |
| 23532 | @end smallexample |
| 23533 | |
| 23534 | |
| 23535 | @subheading The @code{-target-file-get} Command |
| 23536 | @findex -target-file-get |
| 23537 | |
| 23538 | @subsubheading Synopsis |
| 23539 | |
| 23540 | @smallexample |
| 23541 | -target-file-get @var{targetfile} @var{hostfile} |
| 23542 | @end smallexample |
| 23543 | |
| 23544 | Copy file @var{targetfile} from the target system to @var{hostfile} |
| 23545 | on the host system. |
| 23546 | |
| 23547 | @subsubheading @value{GDBN} Command |
| 23548 | |
| 23549 | The corresponding @value{GDBN} command is @samp{remote get}. |
| 23550 | |
| 23551 | @subsubheading Example |
| 23552 | |
| 23553 | @smallexample |
| 23554 | (gdb) |
| 23555 | -target-file-get remotefile localfile |
| 23556 | ^done |
| 23557 | (gdb) |
| 23558 | @end smallexample |
| 23559 | |
| 23560 | |
| 23561 | @subheading The @code{-target-file-delete} Command |
| 23562 | @findex -target-file-delete |
| 23563 | |
| 23564 | @subsubheading Synopsis |
| 23565 | |
| 23566 | @smallexample |
| 23567 | -target-file-delete @var{targetfile} |
| 23568 | @end smallexample |
| 23569 | |
| 23570 | Delete @var{targetfile} from the target system. |
| 23571 | |
| 23572 | @subsubheading @value{GDBN} Command |
| 23573 | |
| 23574 | The corresponding @value{GDBN} command is @samp{remote delete}. |
| 23575 | |
| 23576 | @subsubheading Example |
| 23577 | |
| 23578 | @smallexample |
| 23579 | (gdb) |
| 23580 | -target-file-delete remotefile |
| 23581 | ^done |
| 23582 | (gdb) |
| 23583 | @end smallexample |
| 23584 | |
| 23585 | |
| 23586 | @c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 23587 | @node GDB/MI Miscellaneous Commands |
| 23588 | @section Miscellaneous @sc{gdb/mi} Commands |
| 23589 | |
| 23590 | @c @subheading -gdb-complete |
| 23591 | |
| 23592 | @subheading The @code{-gdb-exit} Command |
| 23593 | @findex -gdb-exit |
| 23594 | |
| 23595 | @subsubheading Synopsis |
| 23596 | |
| 23597 | @smallexample |
| 23598 | -gdb-exit |
| 23599 | @end smallexample |
| 23600 | |
| 23601 | Exit @value{GDBN} immediately. |
| 23602 | |
| 23603 | @subsubheading @value{GDBN} Command |
| 23604 | |
| 23605 | Approximately corresponds to @samp{quit}. |
| 23606 | |
| 23607 | @subsubheading Example |
| 23608 | |
| 23609 | @smallexample |
| 23610 | (gdb) |
| 23611 | -gdb-exit |
| 23612 | ^exit |
| 23613 | @end smallexample |
| 23614 | |
| 23615 | |
| 23616 | @subheading The @code{-exec-abort} Command |
| 23617 | @findex -exec-abort |
| 23618 | |
| 23619 | @subsubheading Synopsis |
| 23620 | |
| 23621 | @smallexample |
| 23622 | -exec-abort |
| 23623 | @end smallexample |
| 23624 | |
| 23625 | Kill the inferior running program. |
| 23626 | |
| 23627 | @subsubheading @value{GDBN} Command |
| 23628 | |
| 23629 | The corresponding @value{GDBN} command is @samp{kill}. |
| 23630 | |
| 23631 | @subsubheading Example |
| 23632 | N.A. |
| 23633 | |
| 23634 | |
| 23635 | @subheading The @code{-gdb-set} Command |
| 23636 | @findex -gdb-set |
| 23637 | |
| 23638 | @subsubheading Synopsis |
| 23639 | |
| 23640 | @smallexample |
| 23641 | -gdb-set |
| 23642 | @end smallexample |
| 23643 | |
| 23644 | Set an internal @value{GDBN} variable. |
| 23645 | @c IS THIS A DOLLAR VARIABLE? OR SOMETHING LIKE ANNOTATE ????? |
| 23646 | |
| 23647 | @subsubheading @value{GDBN} Command |
| 23648 | |
| 23649 | The corresponding @value{GDBN} command is @samp{set}. |
| 23650 | |
| 23651 | @subsubheading Example |
| 23652 | |
| 23653 | @smallexample |
| 23654 | (gdb) |
| 23655 | -gdb-set $foo=3 |
| 23656 | ^done |
| 23657 | (gdb) |
| 23658 | @end smallexample |
| 23659 | |
| 23660 | |
| 23661 | @subheading The @code{-gdb-show} Command |
| 23662 | @findex -gdb-show |
| 23663 | |
| 23664 | @subsubheading Synopsis |
| 23665 | |
| 23666 | @smallexample |
| 23667 | -gdb-show |
| 23668 | @end smallexample |
| 23669 | |
| 23670 | Show the current value of a @value{GDBN} variable. |
| 23671 | |
| 23672 | @subsubheading @value{GDBN} Command |
| 23673 | |
| 23674 | The corresponding @value{GDBN} command is @samp{show}. |
| 23675 | |
| 23676 | @subsubheading Example |
| 23677 | |
| 23678 | @smallexample |
| 23679 | (gdb) |
| 23680 | -gdb-show annotate |
| 23681 | ^done,value="0" |
| 23682 | (gdb) |
| 23683 | @end smallexample |
| 23684 | |
| 23685 | @c @subheading -gdb-source |
| 23686 | |
| 23687 | |
| 23688 | @subheading The @code{-gdb-version} Command |
| 23689 | @findex -gdb-version |
| 23690 | |
| 23691 | @subsubheading Synopsis |
| 23692 | |
| 23693 | @smallexample |
| 23694 | -gdb-version |
| 23695 | @end smallexample |
| 23696 | |
| 23697 | Show version information for @value{GDBN}. Used mostly in testing. |
| 23698 | |
| 23699 | @subsubheading @value{GDBN} Command |
| 23700 | |
| 23701 | The @value{GDBN} equivalent is @samp{show version}. @value{GDBN} by |
| 23702 | default shows this information when you start an interactive session. |
| 23703 | |
| 23704 | @subsubheading Example |
| 23705 | |
| 23706 | @c This example modifies the actual output from GDB to avoid overfull |
| 23707 | @c box in TeX. |
| 23708 | @smallexample |
| 23709 | (gdb) |
| 23710 | -gdb-version |
| 23711 | ~GNU gdb 5.2.1 |
| 23712 | ~Copyright 2000 Free Software Foundation, Inc. |
| 23713 | ~GDB is free software, covered by the GNU General Public License, and |
| 23714 | ~you are welcome to change it and/or distribute copies of it under |
| 23715 | ~ certain conditions. |
| 23716 | ~Type "show copying" to see the conditions. |
| 23717 | ~There is absolutely no warranty for GDB. Type "show warranty" for |
| 23718 | ~ details. |
| 23719 | ~This GDB was configured as |
| 23720 | "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi". |
| 23721 | ^done |
| 23722 | (gdb) |
| 23723 | @end smallexample |
| 23724 | |
| 23725 | @subheading The @code{-list-features} Command |
| 23726 | @findex -list-features |
| 23727 | |
| 23728 | Returns a list of particular features of the MI protocol that |
| 23729 | this version of gdb implements. A feature can be a command, |
| 23730 | or a new field in an output of some command, or even an |
| 23731 | important bugfix. While a frontend can sometimes detect presence |
| 23732 | of a feature at runtime, it is easier to perform detection at debugger |
| 23733 | startup. |
| 23734 | |
| 23735 | The command returns a list of strings, with each string naming an |
| 23736 | available feature. Each returned string is just a name, it does not |
| 23737 | have any internal structure. The list of possible feature names |
| 23738 | is given below. |
| 23739 | |
| 23740 | Example output: |
| 23741 | |
| 23742 | @smallexample |
| 23743 | (gdb) -list-features |
| 23744 | ^done,result=["feature1","feature2"] |
| 23745 | @end smallexample |
| 23746 | |
| 23747 | The current list of features is: |
| 23748 | |
| 23749 | @table @samp |
| 23750 | @item frozen-varobjs |
| 23751 | Indicates presence of the @code{-var-set-frozen} command, as well |
| 23752 | as possible presense of the @code{frozen} field in the output |
| 23753 | of @code{-varobj-create}. |
| 23754 | @item pending-breakpoints |
| 23755 | Indicates presence of the @option{-f} option to the @code{-break-insert} command. |
| 23756 | @item thread-info |
| 23757 | Indicates presence of the @code{-thread-info} command. |
| 23758 | |
| 23759 | @end table |
| 23760 | |
| 23761 | @subheading The @code{-list-target-features} Command |
| 23762 | @findex -list-target-features |
| 23763 | |
| 23764 | Returns a list of particular features that are supported by the |
| 23765 | target. Those features affect the permitted MI commands, but |
| 23766 | unlike the features reported by the @code{-list-features} command, the |
| 23767 | features depend on which target GDB is using at the moment. Whenever |
| 23768 | a target can change, due to commands such as @code{-target-select}, |
| 23769 | @code{-target-attach} or @code{-exec-run}, the list of target features |
| 23770 | may change, and the frontend should obtain it again. |
| 23771 | Example output: |
| 23772 | |
| 23773 | @smallexample |
| 23774 | (gdb) -list-features |
| 23775 | ^done,result=["async"] |
| 23776 | @end smallexample |
| 23777 | |
| 23778 | The current list of features is: |
| 23779 | |
| 23780 | @table @samp |
| 23781 | @item async |
| 23782 | Indicates that the target is capable of asynchronous command |
| 23783 | execution, which means that @value{GDBN} will accept further commands |
| 23784 | while the target is running. |
| 23785 | |
| 23786 | @end table |
| 23787 | |
| 23788 | @subheading The @code{-list-thread-groups} Command |
| 23789 | @findex -list-thread-groups |
| 23790 | |
| 23791 | @subheading Synopsis |
| 23792 | |
| 23793 | @smallexample |
| 23794 | -list-thread-groups [ --available ] [ @var{group} ] |
| 23795 | @end smallexample |
| 23796 | |
| 23797 | When used without the @var{group} parameter, lists top-level thread |
| 23798 | groups that are being debugged. When used with the @var{group} |
| 23799 | parameter, the children of the specified group are listed. The |
| 23800 | children can be either threads, or other groups. At present, |
| 23801 | @value{GDBN} will not report both threads and groups as children at |
| 23802 | the same time, but it may change in future. |
| 23803 | |
| 23804 | With the @samp{--available} option, instead of reporting groups that |
| 23805 | are been debugged, GDB will report all thread groups available on the |
| 23806 | target. Using the @samp{--available} option together with @var{group} |
| 23807 | is not allowed. |
| 23808 | |
| 23809 | @subheading Example |
| 23810 | |
| 23811 | @smallexample |
| 23812 | @value{GDBP} |
| 23813 | -list-thread-groups |
| 23814 | ^done,groups=[@{id="17",type="process",pid="yyy",num_children="2"@}] |
| 23815 | -list-thread-groups 17 |
| 23816 | ^done,threads=[@{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)", |
| 23817 | frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]@},state="running"@}, |
| 23818 | @{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)", |
| 23819 | frame=@{level="0",addr="0x0804891f",func="foo",args=[@{name="i",value="10"@}], |
| 23820 | file="/tmp/a.c",fullname="/tmp/a.c",line="158"@},state="running"@}]] |
| 23821 | @end smallexample |
| 23822 | |
| 23823 | @subheading The @code{-interpreter-exec} Command |
| 23824 | @findex -interpreter-exec |
| 23825 | |
| 23826 | @subheading Synopsis |
| 23827 | |
| 23828 | @smallexample |
| 23829 | -interpreter-exec @var{interpreter} @var{command} |
| 23830 | @end smallexample |
| 23831 | @anchor{-interpreter-exec} |
| 23832 | |
| 23833 | Execute the specified @var{command} in the given @var{interpreter}. |
| 23834 | |
| 23835 | @subheading @value{GDBN} Command |
| 23836 | |
| 23837 | The corresponding @value{GDBN} command is @samp{interpreter-exec}. |
| 23838 | |
| 23839 | @subheading Example |
| 23840 | |
| 23841 | @smallexample |
| 23842 | (gdb) |
| 23843 | -interpreter-exec console "break main" |
| 23844 | &"During symbol reading, couldn't parse type; debugger out of date?.\n" |
| 23845 | &"During symbol reading, bad structure-type format.\n" |
| 23846 | ~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n" |
| 23847 | ^done |
| 23848 | (gdb) |
| 23849 | @end smallexample |
| 23850 | |
| 23851 | @subheading The @code{-inferior-tty-set} Command |
| 23852 | @findex -inferior-tty-set |
| 23853 | |
| 23854 | @subheading Synopsis |
| 23855 | |
| 23856 | @smallexample |
| 23857 | -inferior-tty-set /dev/pts/1 |
| 23858 | @end smallexample |
| 23859 | |
| 23860 | Set terminal for future runs of the program being debugged. |
| 23861 | |
| 23862 | @subheading @value{GDBN} Command |
| 23863 | |
| 23864 | The corresponding @value{GDBN} command is @samp{set inferior-tty} /dev/pts/1. |
| 23865 | |
| 23866 | @subheading Example |
| 23867 | |
| 23868 | @smallexample |
| 23869 | (gdb) |
| 23870 | -inferior-tty-set /dev/pts/1 |
| 23871 | ^done |
| 23872 | (gdb) |
| 23873 | @end smallexample |
| 23874 | |
| 23875 | @subheading The @code{-inferior-tty-show} Command |
| 23876 | @findex -inferior-tty-show |
| 23877 | |
| 23878 | @subheading Synopsis |
| 23879 | |
| 23880 | @smallexample |
| 23881 | -inferior-tty-show |
| 23882 | @end smallexample |
| 23883 | |
| 23884 | Show terminal for future runs of program being debugged. |
| 23885 | |
| 23886 | @subheading @value{GDBN} Command |
| 23887 | |
| 23888 | The corresponding @value{GDBN} command is @samp{show inferior-tty}. |
| 23889 | |
| 23890 | @subheading Example |
| 23891 | |
| 23892 | @smallexample |
| 23893 | (gdb) |
| 23894 | -inferior-tty-set /dev/pts/1 |
| 23895 | ^done |
| 23896 | (gdb) |
| 23897 | -inferior-tty-show |
| 23898 | ^done,inferior_tty_terminal="/dev/pts/1" |
| 23899 | (gdb) |
| 23900 | @end smallexample |
| 23901 | |
| 23902 | @subheading The @code{-enable-timings} Command |
| 23903 | @findex -enable-timings |
| 23904 | |
| 23905 | @subheading Synopsis |
| 23906 | |
| 23907 | @smallexample |
| 23908 | -enable-timings [yes | no] |
| 23909 | @end smallexample |
| 23910 | |
| 23911 | Toggle the printing of the wallclock, user and system times for an MI |
| 23912 | command as a field in its output. This command is to help frontend |
| 23913 | developers optimize the performance of their code. No argument is |
| 23914 | equivalent to @samp{yes}. |
| 23915 | |
| 23916 | @subheading @value{GDBN} Command |
| 23917 | |
| 23918 | No equivalent. |
| 23919 | |
| 23920 | @subheading Example |
| 23921 | |
| 23922 | @smallexample |
| 23923 | (gdb) |
| 23924 | -enable-timings |
| 23925 | ^done |
| 23926 | (gdb) |
| 23927 | -break-insert main |
| 23928 | ^done,bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y", |
| 23929 | addr="0x080484ed",func="main",file="myprog.c", |
| 23930 | fullname="/home/nickrob/myprog.c",line="73",times="0"@}, |
| 23931 | time=@{wallclock="0.05185",user="0.00800",system="0.00000"@} |
| 23932 | (gdb) |
| 23933 | -enable-timings no |
| 23934 | ^done |
| 23935 | (gdb) |
| 23936 | -exec-run |
| 23937 | ^running |
| 23938 | (gdb) |
| 23939 | *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0", |
| 23940 | frame=@{addr="0x080484ed",func="main",args=[@{name="argc",value="1"@}, |
| 23941 | @{name="argv",value="0xbfb60364"@}],file="myprog.c", |
| 23942 | fullname="/home/nickrob/myprog.c",line="73"@} |
| 23943 | (gdb) |
| 23944 | @end smallexample |
| 23945 | |
| 23946 | @node Annotations |
| 23947 | @chapter @value{GDBN} Annotations |
| 23948 | |
| 23949 | This chapter describes annotations in @value{GDBN}. Annotations were |
| 23950 | designed to interface @value{GDBN} to graphical user interfaces or other |
| 23951 | similar programs which want to interact with @value{GDBN} at a |
| 23952 | relatively high level. |
| 23953 | |
| 23954 | The annotation mechanism has largely been superseded by @sc{gdb/mi} |
| 23955 | (@pxref{GDB/MI}). |
| 23956 | |
| 23957 | @ignore |
| 23958 | This is Edition @value{EDITION}, @value{DATE}. |
| 23959 | @end ignore |
| 23960 | |
| 23961 | @menu |
| 23962 | * Annotations Overview:: What annotations are; the general syntax. |
| 23963 | * Server Prefix:: Issuing a command without affecting user state. |
| 23964 | * Prompting:: Annotations marking @value{GDBN}'s need for input. |
| 23965 | * Errors:: Annotations for error messages. |
| 23966 | * Invalidation:: Some annotations describe things now invalid. |
| 23967 | * Annotations for Running:: |
| 23968 | Whether the program is running, how it stopped, etc. |
| 23969 | * Source Annotations:: Annotations describing source code. |
| 23970 | @end menu |
| 23971 | |
| 23972 | @node Annotations Overview |
| 23973 | @section What is an Annotation? |
| 23974 | @cindex annotations |
| 23975 | |
| 23976 | Annotations start with a newline character, two @samp{control-z} |
| 23977 | characters, and the name of the annotation. If there is no additional |
| 23978 | information associated with this annotation, the name of the annotation |
| 23979 | is followed immediately by a newline. If there is additional |
| 23980 | information, the name of the annotation is followed by a space, the |
| 23981 | additional information, and a newline. The additional information |
| 23982 | cannot contain newline characters. |
| 23983 | |
| 23984 | Any output not beginning with a newline and two @samp{control-z} |
| 23985 | characters denotes literal output from @value{GDBN}. Currently there is |
| 23986 | no need for @value{GDBN} to output a newline followed by two |
| 23987 | @samp{control-z} characters, but if there was such a need, the |
| 23988 | annotations could be extended with an @samp{escape} annotation which |
| 23989 | means those three characters as output. |
| 23990 | |
| 23991 | The annotation @var{level}, which is specified using the |
| 23992 | @option{--annotate} command line option (@pxref{Mode Options}), controls |
| 23993 | how much information @value{GDBN} prints together with its prompt, |
| 23994 | values of expressions, source lines, and other types of output. Level 0 |
| 23995 | is for no annotations, level 1 is for use when @value{GDBN} is run as a |
| 23996 | subprocess of @sc{gnu} Emacs, level 3 is the maximum annotation suitable |
| 23997 | for programs that control @value{GDBN}, and level 2 annotations have |
| 23998 | been made obsolete (@pxref{Limitations, , Limitations of the Annotation |
| 23999 | Interface, annotate, GDB's Obsolete Annotations}). |
| 24000 | |
| 24001 | @table @code |
| 24002 | @kindex set annotate |
| 24003 | @item set annotate @var{level} |
| 24004 | The @value{GDBN} command @code{set annotate} sets the level of |
| 24005 | annotations to the specified @var{level}. |
| 24006 | |
| 24007 | @item show annotate |
| 24008 | @kindex show annotate |
| 24009 | Show the current annotation level. |
| 24010 | @end table |
| 24011 | |
| 24012 | This chapter describes level 3 annotations. |
| 24013 | |
| 24014 | A simple example of starting up @value{GDBN} with annotations is: |
| 24015 | |
| 24016 | @smallexample |
| 24017 | $ @kbd{gdb --annotate=3} |
| 24018 | GNU gdb 6.0 |
| 24019 | Copyright 2003 Free Software Foundation, Inc. |
| 24020 | GDB is free software, covered by the GNU General Public License, |
| 24021 | and you are welcome to change it and/or distribute copies of it |
| 24022 | under certain conditions. |
| 24023 | Type "show copying" to see the conditions. |
| 24024 | There is absolutely no warranty for GDB. Type "show warranty" |
| 24025 | for details. |
| 24026 | This GDB was configured as "i386-pc-linux-gnu" |
| 24027 | |
| 24028 | ^Z^Zpre-prompt |
| 24029 | (@value{GDBP}) |
| 24030 | ^Z^Zprompt |
| 24031 | @kbd{quit} |
| 24032 | |
| 24033 | ^Z^Zpost-prompt |
| 24034 | $ |
| 24035 | @end smallexample |
| 24036 | |
| 24037 | Here @samp{quit} is input to @value{GDBN}; the rest is output from |
| 24038 | @value{GDBN}. The three lines beginning @samp{^Z^Z} (where @samp{^Z} |
| 24039 | denotes a @samp{control-z} character) are annotations; the rest is |
| 24040 | output from @value{GDBN}. |
| 24041 | |
| 24042 | @node Server Prefix |
| 24043 | @section The Server Prefix |
| 24044 | @cindex server prefix |
| 24045 | |
| 24046 | If you prefix a command with @samp{server } then it will not affect |
| 24047 | the command history, nor will it affect @value{GDBN}'s notion of which |
| 24048 | command to repeat if @key{RET} is pressed on a line by itself. This |
| 24049 | means that commands can be run behind a user's back by a front-end in |
| 24050 | a transparent manner. |
| 24051 | |
| 24052 | The server prefix does not affect the recording of values into the value |
| 24053 | history; to print a value without recording it into the value history, |
| 24054 | use the @code{output} command instead of the @code{print} command. |
| 24055 | |
| 24056 | @node Prompting |
| 24057 | @section Annotation for @value{GDBN} Input |
| 24058 | |
| 24059 | @cindex annotations for prompts |
| 24060 | When @value{GDBN} prompts for input, it annotates this fact so it is possible |
| 24061 | to know when to send output, when the output from a given command is |
| 24062 | over, etc. |
| 24063 | |
| 24064 | Different kinds of input each have a different @dfn{input type}. Each |
| 24065 | input type has three annotations: a @code{pre-} annotation, which |
| 24066 | denotes the beginning of any prompt which is being output, a plain |
| 24067 | annotation, which denotes the end of the prompt, and then a @code{post-} |
| 24068 | annotation which denotes the end of any echo which may (or may not) be |
| 24069 | associated with the input. For example, the @code{prompt} input type |
| 24070 | features the following annotations: |
| 24071 | |
| 24072 | @smallexample |
| 24073 | ^Z^Zpre-prompt |
| 24074 | ^Z^Zprompt |
| 24075 | ^Z^Zpost-prompt |
| 24076 | @end smallexample |
| 24077 | |
| 24078 | The input types are |
| 24079 | |
| 24080 | @table @code |
| 24081 | @findex pre-prompt annotation |
| 24082 | @findex prompt annotation |
| 24083 | @findex post-prompt annotation |
| 24084 | @item prompt |
| 24085 | When @value{GDBN} is prompting for a command (the main @value{GDBN} prompt). |
| 24086 | |
| 24087 | @findex pre-commands annotation |
| 24088 | @findex commands annotation |
| 24089 | @findex post-commands annotation |
| 24090 | @item commands |
| 24091 | When @value{GDBN} prompts for a set of commands, like in the @code{commands} |
| 24092 | command. The annotations are repeated for each command which is input. |
| 24093 | |
| 24094 | @findex pre-overload-choice annotation |
| 24095 | @findex overload-choice annotation |
| 24096 | @findex post-overload-choice annotation |
| 24097 | @item overload-choice |
| 24098 | When @value{GDBN} wants the user to select between various overloaded functions. |
| 24099 | |
| 24100 | @findex pre-query annotation |
| 24101 | @findex query annotation |
| 24102 | @findex post-query annotation |
| 24103 | @item query |
| 24104 | When @value{GDBN} wants the user to confirm a potentially dangerous operation. |
| 24105 | |
| 24106 | @findex pre-prompt-for-continue annotation |
| 24107 | @findex prompt-for-continue annotation |
| 24108 | @findex post-prompt-for-continue annotation |
| 24109 | @item prompt-for-continue |
| 24110 | When @value{GDBN} is asking the user to press return to continue. Note: Don't |
| 24111 | expect this to work well; instead use @code{set height 0} to disable |
| 24112 | prompting. This is because the counting of lines is buggy in the |
| 24113 | presence of annotations. |
| 24114 | @end table |
| 24115 | |
| 24116 | @node Errors |
| 24117 | @section Errors |
| 24118 | @cindex annotations for errors, warnings and interrupts |
| 24119 | |
| 24120 | @findex quit annotation |
| 24121 | @smallexample |
| 24122 | ^Z^Zquit |
| 24123 | @end smallexample |
| 24124 | |
| 24125 | This annotation occurs right before @value{GDBN} responds to an interrupt. |
| 24126 | |
| 24127 | @findex error annotation |
| 24128 | @smallexample |
| 24129 | ^Z^Zerror |
| 24130 | @end smallexample |
| 24131 | |
| 24132 | This annotation occurs right before @value{GDBN} responds to an error. |
| 24133 | |
| 24134 | Quit and error annotations indicate that any annotations which @value{GDBN} was |
| 24135 | in the middle of may end abruptly. For example, if a |
| 24136 | @code{value-history-begin} annotation is followed by a @code{error}, one |
| 24137 | cannot expect to receive the matching @code{value-history-end}. One |
| 24138 | cannot expect not to receive it either, however; an error annotation |
| 24139 | does not necessarily mean that @value{GDBN} is immediately returning all the way |
| 24140 | to the top level. |
| 24141 | |
| 24142 | @findex error-begin annotation |
| 24143 | A quit or error annotation may be preceded by |
| 24144 | |
| 24145 | @smallexample |
| 24146 | ^Z^Zerror-begin |
| 24147 | @end smallexample |
| 24148 | |
| 24149 | Any output between that and the quit or error annotation is the error |
| 24150 | message. |
| 24151 | |
| 24152 | Warning messages are not yet annotated. |
| 24153 | @c If we want to change that, need to fix warning(), type_error(), |
| 24154 | @c range_error(), and possibly other places. |
| 24155 | |
| 24156 | @node Invalidation |
| 24157 | @section Invalidation Notices |
| 24158 | |
| 24159 | @cindex annotations for invalidation messages |
| 24160 | The following annotations say that certain pieces of state may have |
| 24161 | changed. |
| 24162 | |
| 24163 | @table @code |
| 24164 | @findex frames-invalid annotation |
| 24165 | @item ^Z^Zframes-invalid |
| 24166 | |
| 24167 | The frames (for example, output from the @code{backtrace} command) may |
| 24168 | have changed. |
| 24169 | |
| 24170 | @findex breakpoints-invalid annotation |
| 24171 | @item ^Z^Zbreakpoints-invalid |
| 24172 | |
| 24173 | The breakpoints may have changed. For example, the user just added or |
| 24174 | deleted a breakpoint. |
| 24175 | @end table |
| 24176 | |
| 24177 | @node Annotations for Running |
| 24178 | @section Running the Program |
| 24179 | @cindex annotations for running programs |
| 24180 | |
| 24181 | @findex starting annotation |
| 24182 | @findex stopping annotation |
| 24183 | When the program starts executing due to a @value{GDBN} command such as |
| 24184 | @code{step} or @code{continue}, |
| 24185 | |
| 24186 | @smallexample |
| 24187 | ^Z^Zstarting |
| 24188 | @end smallexample |
| 24189 | |
| 24190 | is output. When the program stops, |
| 24191 | |
| 24192 | @smallexample |
| 24193 | ^Z^Zstopped |
| 24194 | @end smallexample |
| 24195 | |
| 24196 | is output. Before the @code{stopped} annotation, a variety of |
| 24197 | annotations describe how the program stopped. |
| 24198 | |
| 24199 | @table @code |
| 24200 | @findex exited annotation |
| 24201 | @item ^Z^Zexited @var{exit-status} |
| 24202 | The program exited, and @var{exit-status} is the exit status (zero for |
| 24203 | successful exit, otherwise nonzero). |
| 24204 | |
| 24205 | @findex signalled annotation |
| 24206 | @findex signal-name annotation |
| 24207 | @findex signal-name-end annotation |
| 24208 | @findex signal-string annotation |
| 24209 | @findex signal-string-end annotation |
| 24210 | @item ^Z^Zsignalled |
| 24211 | The program exited with a signal. After the @code{^Z^Zsignalled}, the |
| 24212 | annotation continues: |
| 24213 | |
| 24214 | @smallexample |
| 24215 | @var{intro-text} |
| 24216 | ^Z^Zsignal-name |
| 24217 | @var{name} |
| 24218 | ^Z^Zsignal-name-end |
| 24219 | @var{middle-text} |
| 24220 | ^Z^Zsignal-string |
| 24221 | @var{string} |
| 24222 | ^Z^Zsignal-string-end |
| 24223 | @var{end-text} |
| 24224 | @end smallexample |
| 24225 | |
| 24226 | @noindent |
| 24227 | where @var{name} is the name of the signal, such as @code{SIGILL} or |
| 24228 | @code{SIGSEGV}, and @var{string} is the explanation of the signal, such |
| 24229 | as @code{Illegal Instruction} or @code{Segmentation fault}. |
| 24230 | @var{intro-text}, @var{middle-text}, and @var{end-text} are for the |
| 24231 | user's benefit and have no particular format. |
| 24232 | |
| 24233 | @findex signal annotation |
| 24234 | @item ^Z^Zsignal |
| 24235 | The syntax of this annotation is just like @code{signalled}, but @value{GDBN} is |
| 24236 | just saying that the program received the signal, not that it was |
| 24237 | terminated with it. |
| 24238 | |
| 24239 | @findex breakpoint annotation |
| 24240 | @item ^Z^Zbreakpoint @var{number} |
| 24241 | The program hit breakpoint number @var{number}. |
| 24242 | |
| 24243 | @findex watchpoint annotation |
| 24244 | @item ^Z^Zwatchpoint @var{number} |
| 24245 | The program hit watchpoint number @var{number}. |
| 24246 | @end table |
| 24247 | |
| 24248 | @node Source Annotations |
| 24249 | @section Displaying Source |
| 24250 | @cindex annotations for source display |
| 24251 | |
| 24252 | @findex source annotation |
| 24253 | The following annotation is used instead of displaying source code: |
| 24254 | |
| 24255 | @smallexample |
| 24256 | ^Z^Zsource @var{filename}:@var{line}:@var{character}:@var{middle}:@var{addr} |
| 24257 | @end smallexample |
| 24258 | |
| 24259 | where @var{filename} is an absolute file name indicating which source |
| 24260 | file, @var{line} is the line number within that file (where 1 is the |
| 24261 | first line in the file), @var{character} is the character position |
| 24262 | within the file (where 0 is the first character in the file) (for most |
| 24263 | debug formats this will necessarily point to the beginning of a line), |
| 24264 | @var{middle} is @samp{middle} if @var{addr} is in the middle of the |
| 24265 | line, or @samp{beg} if @var{addr} is at the beginning of the line, and |
| 24266 | @var{addr} is the address in the target program associated with the |
| 24267 | source which is being displayed. @var{addr} is in the form @samp{0x} |
| 24268 | followed by one or more lowercase hex digits (note that this does not |
| 24269 | depend on the language). |
| 24270 | |
| 24271 | @node GDB Bugs |
| 24272 | @chapter Reporting Bugs in @value{GDBN} |
| 24273 | @cindex bugs in @value{GDBN} |
| 24274 | @cindex reporting bugs in @value{GDBN} |
| 24275 | |
| 24276 | Your bug reports play an essential role in making @value{GDBN} reliable. |
| 24277 | |
| 24278 | Reporting a bug may help you by bringing a solution to your problem, or it |
| 24279 | may not. But in any case the principal function of a bug report is to help |
| 24280 | the entire community by making the next version of @value{GDBN} work better. Bug |
| 24281 | reports are your contribution to the maintenance of @value{GDBN}. |
| 24282 | |
| 24283 | In order for a bug report to serve its purpose, you must include the |
| 24284 | information that enables us to fix the bug. |
| 24285 | |
| 24286 | @menu |
| 24287 | * Bug Criteria:: Have you found a bug? |
| 24288 | * Bug Reporting:: How to report bugs |
| 24289 | @end menu |
| 24290 | |
| 24291 | @node Bug Criteria |
| 24292 | @section Have You Found a Bug? |
| 24293 | @cindex bug criteria |
| 24294 | |
| 24295 | If you are not sure whether you have found a bug, here are some guidelines: |
| 24296 | |
| 24297 | @itemize @bullet |
| 24298 | @cindex fatal signal |
| 24299 | @cindex debugger crash |
| 24300 | @cindex crash of debugger |
| 24301 | @item |
| 24302 | If the debugger gets a fatal signal, for any input whatever, that is a |
| 24303 | @value{GDBN} bug. Reliable debuggers never crash. |
| 24304 | |
| 24305 | @cindex error on valid input |
| 24306 | @item |
| 24307 | If @value{GDBN} produces an error message for valid input, that is a |
| 24308 | bug. (Note that if you're cross debugging, the problem may also be |
| 24309 | somewhere in the connection to the target.) |
| 24310 | |
| 24311 | @cindex invalid input |
| 24312 | @item |
| 24313 | If @value{GDBN} does not produce an error message for invalid input, |
| 24314 | that is a bug. However, you should note that your idea of |
| 24315 | ``invalid input'' might be our idea of ``an extension'' or ``support |
| 24316 | for traditional practice''. |
| 24317 | |
| 24318 | @item |
| 24319 | If you are an experienced user of debugging tools, your suggestions |
| 24320 | for improvement of @value{GDBN} are welcome in any case. |
| 24321 | @end itemize |
| 24322 | |
| 24323 | @node Bug Reporting |
| 24324 | @section How to Report Bugs |
| 24325 | @cindex bug reports |
| 24326 | @cindex @value{GDBN} bugs, reporting |
| 24327 | |
| 24328 | A number of companies and individuals offer support for @sc{gnu} products. |
| 24329 | If you obtained @value{GDBN} from a support organization, we recommend you |
| 24330 | contact that organization first. |
| 24331 | |
| 24332 | You can find contact information for many support companies and |
| 24333 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs |
| 24334 | distribution. |
| 24335 | @c should add a web page ref... |
| 24336 | |
| 24337 | @ifset BUGURL |
| 24338 | @ifset BUGURL_DEFAULT |
| 24339 | In any event, we also recommend that you submit bug reports for |
| 24340 | @value{GDBN}. The preferred method is to submit them directly using |
| 24341 | @uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web |
| 24342 | page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can |
| 24343 | be used. |
| 24344 | |
| 24345 | @strong{Do not send bug reports to @samp{info-gdb}, or to |
| 24346 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do |
| 24347 | not want to receive bug reports. Those that do have arranged to receive |
| 24348 | @samp{bug-gdb}. |
| 24349 | |
| 24350 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which |
| 24351 | serves as a repeater. The mailing list and the newsgroup carry exactly |
| 24352 | the same messages. Often people think of posting bug reports to the |
| 24353 | newsgroup instead of mailing them. This appears to work, but it has one |
| 24354 | problem which can be crucial: a newsgroup posting often lacks a mail |
| 24355 | path back to the sender. Thus, if we need to ask for more information, |
| 24356 | we may be unable to reach you. For this reason, it is better to send |
| 24357 | bug reports to the mailing list. |
| 24358 | @end ifset |
| 24359 | @ifclear BUGURL_DEFAULT |
| 24360 | In any event, we also recommend that you submit bug reports for |
| 24361 | @value{GDBN} to @value{BUGURL}. |
| 24362 | @end ifclear |
| 24363 | @end ifset |
| 24364 | |
| 24365 | The fundamental principle of reporting bugs usefully is this: |
| 24366 | @strong{report all the facts}. If you are not sure whether to state a |
| 24367 | fact or leave it out, state it! |
| 24368 | |
| 24369 | Often people omit facts because they think they know what causes the |
| 24370 | problem and assume that some details do not matter. Thus, you might |
| 24371 | assume that the name of the variable you use in an example does not matter. |
| 24372 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a |
| 24373 | stray memory reference which happens to fetch from the location where that |
| 24374 | name is stored in memory; perhaps, if the name were different, the contents |
| 24375 | of that location would fool the debugger into doing the right thing despite |
| 24376 | the bug. Play it safe and give a specific, complete example. That is the |
| 24377 | easiest thing for you to do, and the most helpful. |
| 24378 | |
| 24379 | Keep in mind that the purpose of a bug report is to enable us to fix the |
| 24380 | bug. It may be that the bug has been reported previously, but neither |
| 24381 | you nor we can know that unless your bug report is complete and |
| 24382 | self-contained. |
| 24383 | |
| 24384 | Sometimes people give a few sketchy facts and ask, ``Does this ring a |
| 24385 | bell?'' Those bug reports are useless, and we urge everyone to |
| 24386 | @emph{refuse to respond to them} except to chide the sender to report |
| 24387 | bugs properly. |
| 24388 | |
| 24389 | To enable us to fix the bug, you should include all these things: |
| 24390 | |
| 24391 | @itemize @bullet |
| 24392 | @item |
| 24393 | The version of @value{GDBN}. @value{GDBN} announces it if you start |
| 24394 | with no arguments; you can also print it at any time using @code{show |
| 24395 | version}. |
| 24396 | |
| 24397 | Without this, we will not know whether there is any point in looking for |
| 24398 | the bug in the current version of @value{GDBN}. |
| 24399 | |
| 24400 | @item |
| 24401 | The type of machine you are using, and the operating system name and |
| 24402 | version number. |
| 24403 | |
| 24404 | @item |
| 24405 | What compiler (and its version) was used to compile @value{GDBN}---e.g.@: |
| 24406 | ``@value{GCC}--2.8.1''. |
| 24407 | |
| 24408 | @item |
| 24409 | What compiler (and its version) was used to compile the program you are |
| 24410 | debugging---e.g.@: ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP |
| 24411 | C Compiler''. For @value{NGCC}, you can say @kbd{@value{GCC} --version} |
| 24412 | to get this information; for other compilers, see the documentation for |
| 24413 | those compilers. |
| 24414 | |
| 24415 | @item |
| 24416 | The command arguments you gave the compiler to compile your example and |
| 24417 | observe the bug. For example, did you use @samp{-O}? To guarantee |
| 24418 | you will not omit something important, list them all. A copy of the |
| 24419 | Makefile (or the output from make) is sufficient. |
| 24420 | |
| 24421 | If we were to try to guess the arguments, we would probably guess wrong |
| 24422 | and then we might not encounter the bug. |
| 24423 | |
| 24424 | @item |
| 24425 | A complete input script, and all necessary source files, that will |
| 24426 | reproduce the bug. |
| 24427 | |
| 24428 | @item |
| 24429 | A description of what behavior you observe that you believe is |
| 24430 | incorrect. For example, ``It gets a fatal signal.'' |
| 24431 | |
| 24432 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we |
| 24433 | will certainly notice it. But if the bug is incorrect output, we might |
| 24434 | not notice unless it is glaringly wrong. You might as well not give us |
| 24435 | a chance to make a mistake. |
| 24436 | |
| 24437 | Even if the problem you experience is a fatal signal, you should still |
| 24438 | say so explicitly. Suppose something strange is going on, such as, your |
| 24439 | copy of @value{GDBN} is out of synch, or you have encountered a bug in |
| 24440 | the C library on your system. (This has happened!) Your copy might |
| 24441 | crash and ours would not. If you told us to expect a crash, then when |
| 24442 | ours fails to crash, we would know that the bug was not happening for |
| 24443 | us. If you had not told us to expect a crash, then we would not be able |
| 24444 | to draw any conclusion from our observations. |
| 24445 | |
| 24446 | @pindex script |
| 24447 | @cindex recording a session script |
| 24448 | To collect all this information, you can use a session recording program |
| 24449 | such as @command{script}, which is available on many Unix systems. |
| 24450 | Just run your @value{GDBN} session inside @command{script} and then |
| 24451 | include the @file{typescript} file with your bug report. |
| 24452 | |
| 24453 | Another way to record a @value{GDBN} session is to run @value{GDBN} |
| 24454 | inside Emacs and then save the entire buffer to a file. |
| 24455 | |
| 24456 | @item |
| 24457 | If you wish to suggest changes to the @value{GDBN} source, send us context |
| 24458 | diffs. If you even discuss something in the @value{GDBN} source, refer to |
| 24459 | it by context, not by line number. |
| 24460 | |
| 24461 | The line numbers in our development sources will not match those in your |
| 24462 | sources. Your line numbers would convey no useful information to us. |
| 24463 | |
| 24464 | @end itemize |
| 24465 | |
| 24466 | Here are some things that are not necessary: |
| 24467 | |
| 24468 | @itemize @bullet |
| 24469 | @item |
| 24470 | A description of the envelope of the bug. |
| 24471 | |
| 24472 | Often people who encounter a bug spend a lot of time investigating |
| 24473 | which changes to the input file will make the bug go away and which |
| 24474 | changes will not affect it. |
| 24475 | |
| 24476 | This is often time consuming and not very useful, because the way we |
| 24477 | will find the bug is by running a single example under the debugger |
| 24478 | with breakpoints, not by pure deduction from a series of examples. |
| 24479 | We recommend that you save your time for something else. |
| 24480 | |
| 24481 | Of course, if you can find a simpler example to report @emph{instead} |
| 24482 | of the original one, that is a convenience for us. Errors in the |
| 24483 | output will be easier to spot, running under the debugger will take |
| 24484 | less time, and so on. |
| 24485 | |
| 24486 | However, simplification is not vital; if you do not want to do this, |
| 24487 | report the bug anyway and send us the entire test case you used. |
| 24488 | |
| 24489 | @item |
| 24490 | A patch for the bug. |
| 24491 | |
| 24492 | A patch for the bug does help us if it is a good one. But do not omit |
| 24493 | the necessary information, such as the test case, on the assumption that |
| 24494 | a patch is all we need. We might see problems with your patch and decide |
| 24495 | to fix the problem another way, or we might not understand it at all. |
| 24496 | |
| 24497 | Sometimes with a program as complicated as @value{GDBN} it is very hard to |
| 24498 | construct an example that will make the program follow a certain path |
| 24499 | through the code. If you do not send us the example, we will not be able |
| 24500 | to construct one, so we will not be able to verify that the bug is fixed. |
| 24501 | |
| 24502 | And if we cannot understand what bug you are trying to fix, or why your |
| 24503 | patch should be an improvement, we will not install it. A test case will |
| 24504 | help us to understand. |
| 24505 | |
| 24506 | @item |
| 24507 | A guess about what the bug is or what it depends on. |
| 24508 | |
| 24509 | Such guesses are usually wrong. Even we cannot guess right about such |
| 24510 | things without first using the debugger to find the facts. |
| 24511 | @end itemize |
| 24512 | |
| 24513 | @c The readline documentation is distributed with the readline code |
| 24514 | @c and consists of the two following files: |
| 24515 | @c rluser.texinfo |
| 24516 | @c inc-hist.texinfo |
| 24517 | @c Use -I with makeinfo to point to the appropriate directory, |
| 24518 | @c environment var TEXINPUTS with TeX. |
| 24519 | @include rluser.texi |
| 24520 | @include inc-hist.texinfo |
| 24521 | |
| 24522 | |
| 24523 | @node Formatting Documentation |
| 24524 | @appendix Formatting Documentation |
| 24525 | |
| 24526 | @cindex @value{GDBN} reference card |
| 24527 | @cindex reference card |
| 24528 | The @value{GDBN} 4 release includes an already-formatted reference card, ready |
| 24529 | for printing with PostScript or Ghostscript, in the @file{gdb} |
| 24530 | subdirectory of the main source directory@footnote{In |
| 24531 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} |
| 24532 | release.}. If you can use PostScript or Ghostscript with your printer, |
| 24533 | you can print the reference card immediately with @file{refcard.ps}. |
| 24534 | |
| 24535 | The release also includes the source for the reference card. You |
| 24536 | can format it, using @TeX{}, by typing: |
| 24537 | |
| 24538 | @smallexample |
| 24539 | make refcard.dvi |
| 24540 | @end smallexample |
| 24541 | |
| 24542 | The @value{GDBN} reference card is designed to print in @dfn{landscape} |
| 24543 | mode on US ``letter'' size paper; |
| 24544 | that is, on a sheet 11 inches wide by 8.5 inches |
| 24545 | high. You will need to specify this form of printing as an option to |
| 24546 | your @sc{dvi} output program. |
| 24547 | |
| 24548 | @cindex documentation |
| 24549 | |
| 24550 | All the documentation for @value{GDBN} comes as part of the machine-readable |
| 24551 | distribution. The documentation is written in Texinfo format, which is |
| 24552 | a documentation system that uses a single source file to produce both |
| 24553 | on-line information and a printed manual. You can use one of the Info |
| 24554 | formatting commands to create the on-line version of the documentation |
| 24555 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. |
| 24556 | |
| 24557 | @value{GDBN} includes an already formatted copy of the on-line Info |
| 24558 | version of this manual in the @file{gdb} subdirectory. The main Info |
| 24559 | file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to |
| 24560 | subordinate files matching @samp{gdb.info*} in the same directory. If |
| 24561 | necessary, you can print out these files, or read them with any editor; |
| 24562 | but they are easier to read using the @code{info} subsystem in @sc{gnu} |
| 24563 | Emacs or the standalone @code{info} program, available as part of the |
| 24564 | @sc{gnu} Texinfo distribution. |
| 24565 | |
| 24566 | If you want to format these Info files yourself, you need one of the |
| 24567 | Info formatting programs, such as @code{texinfo-format-buffer} or |
| 24568 | @code{makeinfo}. |
| 24569 | |
| 24570 | If you have @code{makeinfo} installed, and are in the top level |
| 24571 | @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of |
| 24572 | version @value{GDBVN}), you can make the Info file by typing: |
| 24573 | |
| 24574 | @smallexample |
| 24575 | cd gdb |
| 24576 | make gdb.info |
| 24577 | @end smallexample |
| 24578 | |
| 24579 | If you want to typeset and print copies of this manual, you need @TeX{}, |
| 24580 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the |
| 24581 | Texinfo definitions file. |
| 24582 | |
| 24583 | @TeX{} is a typesetting program; it does not print files directly, but |
| 24584 | produces output files called @sc{dvi} files. To print a typeset |
| 24585 | document, you need a program to print @sc{dvi} files. If your system |
| 24586 | has @TeX{} installed, chances are it has such a program. The precise |
| 24587 | command to use depends on your system; @kbd{lpr -d} is common; another |
| 24588 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may |
| 24589 | require a file name without any extension or a @samp{.dvi} extension. |
| 24590 | |
| 24591 | @TeX{} also requires a macro definitions file called |
| 24592 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document |
| 24593 | written in Texinfo format. On its own, @TeX{} cannot either read or |
| 24594 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB |
| 24595 | and is located in the @file{gdb-@var{version-number}/texinfo} |
| 24596 | directory. |
| 24597 | |
| 24598 | If you have @TeX{} and a @sc{dvi} printer program installed, you can |
| 24599 | typeset and print this manual. First switch to the @file{gdb} |
| 24600 | subdirectory of the main source directory (for example, to |
| 24601 | @file{gdb-@value{GDBVN}/gdb}) and type: |
| 24602 | |
| 24603 | @smallexample |
| 24604 | make gdb.dvi |
| 24605 | @end smallexample |
| 24606 | |
| 24607 | Then give @file{gdb.dvi} to your @sc{dvi} printing program. |
| 24608 | |
| 24609 | @node Installing GDB |
| 24610 | @appendix Installing @value{GDBN} |
| 24611 | @cindex installation |
| 24612 | |
| 24613 | @menu |
| 24614 | * Requirements:: Requirements for building @value{GDBN} |
| 24615 | * Running Configure:: Invoking the @value{GDBN} @file{configure} script |
| 24616 | * Separate Objdir:: Compiling @value{GDBN} in another directory |
| 24617 | * Config Names:: Specifying names for hosts and targets |
| 24618 | * Configure Options:: Summary of options for configure |
| 24619 | * System-wide configuration:: Having a system-wide init file |
| 24620 | @end menu |
| 24621 | |
| 24622 | @node Requirements |
| 24623 | @section Requirements for Building @value{GDBN} |
| 24624 | @cindex building @value{GDBN}, requirements for |
| 24625 | |
| 24626 | Building @value{GDBN} requires various tools and packages to be available. |
| 24627 | Other packages will be used only if they are found. |
| 24628 | |
| 24629 | @heading Tools/Packages Necessary for Building @value{GDBN} |
| 24630 | @table @asis |
| 24631 | @item ISO C90 compiler |
| 24632 | @value{GDBN} is written in ISO C90. It should be buildable with any |
| 24633 | working C90 compiler, e.g.@: GCC. |
| 24634 | |
| 24635 | @end table |
| 24636 | |
| 24637 | @heading Tools/Packages Optional for Building @value{GDBN} |
| 24638 | @table @asis |
| 24639 | @item Expat |
| 24640 | @anchor{Expat} |
| 24641 | @value{GDBN} can use the Expat XML parsing library. This library may be |
| 24642 | included with your operating system distribution; if it is not, you |
| 24643 | can get the latest version from @url{http://expat.sourceforge.net}. |
| 24644 | The @file{configure} script will search for this library in several |
| 24645 | standard locations; if it is installed in an unusual path, you can |
| 24646 | use the @option{--with-libexpat-prefix} option to specify its location. |
| 24647 | |
| 24648 | Expat is used for: |
| 24649 | |
| 24650 | @itemize @bullet |
| 24651 | @item |
| 24652 | Remote protocol memory maps (@pxref{Memory Map Format}) |
| 24653 | @item |
| 24654 | Target descriptions (@pxref{Target Descriptions}) |
| 24655 | @item |
| 24656 | Remote shared library lists (@pxref{Library List Format}) |
| 24657 | @item |
| 24658 | MS-Windows shared libraries (@pxref{Shared Libraries}) |
| 24659 | @end itemize |
| 24660 | |
| 24661 | @item zlib |
| 24662 | @cindex compressed debug sections |
| 24663 | @value{GDBN} will use the @samp{zlib} library, if available, to read |
| 24664 | compressed debug sections. Some linkers, such as GNU gold, are capable |
| 24665 | of producing binaries with compressed debug sections. If @value{GDBN} |
| 24666 | is compiled with @samp{zlib}, it will be able to read the debug |
| 24667 | information in such binaries. |
| 24668 | |
| 24669 | The @samp{zlib} library is likely included with your operating system |
| 24670 | distribution; if it is not, you can get the latest version from |
| 24671 | @url{http://zlib.net}. |
| 24672 | |
| 24673 | @end table |
| 24674 | |
| 24675 | @node Running Configure |
| 24676 | @section Invoking the @value{GDBN} @file{configure} Script |
| 24677 | @cindex configuring @value{GDBN} |
| 24678 | @value{GDBN} comes with a @file{configure} script that automates the process |
| 24679 | of preparing @value{GDBN} for installation; you can then use @code{make} to |
| 24680 | build the @code{gdb} program. |
| 24681 | @iftex |
| 24682 | @c irrelevant in info file; it's as current as the code it lives with. |
| 24683 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, |
| 24684 | look at the @file{README} file in the sources; we may have improved the |
| 24685 | installation procedures since publishing this manual.} |
| 24686 | @end iftex |
| 24687 | |
| 24688 | The @value{GDBN} distribution includes all the source code you need for |
| 24689 | @value{GDBN} in a single directory, whose name is usually composed by |
| 24690 | appending the version number to @samp{gdb}. |
| 24691 | |
| 24692 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the |
| 24693 | @file{gdb-@value{GDBVN}} directory. That directory contains: |
| 24694 | |
| 24695 | @table @code |
| 24696 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} |
| 24697 | script for configuring @value{GDBN} and all its supporting libraries |
| 24698 | |
| 24699 | @item gdb-@value{GDBVN}/gdb |
| 24700 | the source specific to @value{GDBN} itself |
| 24701 | |
| 24702 | @item gdb-@value{GDBVN}/bfd |
| 24703 | source for the Binary File Descriptor library |
| 24704 | |
| 24705 | @item gdb-@value{GDBVN}/include |
| 24706 | @sc{gnu} include files |
| 24707 | |
| 24708 | @item gdb-@value{GDBVN}/libiberty |
| 24709 | source for the @samp{-liberty} free software library |
| 24710 | |
| 24711 | @item gdb-@value{GDBVN}/opcodes |
| 24712 | source for the library of opcode tables and disassemblers |
| 24713 | |
| 24714 | @item gdb-@value{GDBVN}/readline |
| 24715 | source for the @sc{gnu} command-line interface |
| 24716 | |
| 24717 | @item gdb-@value{GDBVN}/glob |
| 24718 | source for the @sc{gnu} filename pattern-matching subroutine |
| 24719 | |
| 24720 | @item gdb-@value{GDBVN}/mmalloc |
| 24721 | source for the @sc{gnu} memory-mapped malloc package |
| 24722 | @end table |
| 24723 | |
| 24724 | The simplest way to configure and build @value{GDBN} is to run @file{configure} |
| 24725 | from the @file{gdb-@var{version-number}} source directory, which in |
| 24726 | this example is the @file{gdb-@value{GDBVN}} directory. |
| 24727 | |
| 24728 | First switch to the @file{gdb-@var{version-number}} source directory |
| 24729 | if you are not already in it; then run @file{configure}. Pass the |
| 24730 | identifier for the platform on which @value{GDBN} will run as an |
| 24731 | argument. |
| 24732 | |
| 24733 | For example: |
| 24734 | |
| 24735 | @smallexample |
| 24736 | cd gdb-@value{GDBVN} |
| 24737 | ./configure @var{host} |
| 24738 | make |
| 24739 | @end smallexample |
| 24740 | |
| 24741 | @noindent |
| 24742 | where @var{host} is an identifier such as @samp{sun4} or |
| 24743 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. |
| 24744 | (You can often leave off @var{host}; @file{configure} tries to guess the |
| 24745 | correct value by examining your system.) |
| 24746 | |
| 24747 | Running @samp{configure @var{host}} and then running @code{make} builds the |
| 24748 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} |
| 24749 | libraries, then @code{gdb} itself. The configured source files, and the |
| 24750 | binaries, are left in the corresponding source directories. |
| 24751 | |
| 24752 | @need 750 |
| 24753 | @file{configure} is a Bourne-shell (@code{/bin/sh}) script; if your |
| 24754 | system does not recognize this automatically when you run a different |
| 24755 | shell, you may need to run @code{sh} on it explicitly: |
| 24756 | |
| 24757 | @smallexample |
| 24758 | sh configure @var{host} |
| 24759 | @end smallexample |
| 24760 | |
| 24761 | If you run @file{configure} from a directory that contains source |
| 24762 | directories for multiple libraries or programs, such as the |
| 24763 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, |
| 24764 | @file{configure} |
| 24765 | creates configuration files for every directory level underneath (unless |
| 24766 | you tell it not to, with the @samp{--norecursion} option). |
| 24767 | |
| 24768 | You should run the @file{configure} script from the top directory in the |
| 24769 | source tree, the @file{gdb-@var{version-number}} directory. If you run |
| 24770 | @file{configure} from one of the subdirectories, you will configure only |
| 24771 | that subdirectory. That is usually not what you want. In particular, |
| 24772 | if you run the first @file{configure} from the @file{gdb} subdirectory |
| 24773 | of the @file{gdb-@var{version-number}} directory, you will omit the |
| 24774 | configuration of @file{bfd}, @file{readline}, and other sibling |
| 24775 | directories of the @file{gdb} subdirectory. This leads to build errors |
| 24776 | about missing include files such as @file{bfd/bfd.h}. |
| 24777 | |
| 24778 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. |
| 24779 | However, you should make sure that the shell on your path (named by |
| 24780 | the @samp{SHELL} environment variable) is publicly readable. Remember |
| 24781 | that @value{GDBN} uses the shell to start your program---some systems refuse to |
| 24782 | let @value{GDBN} debug child processes whose programs are not readable. |
| 24783 | |
| 24784 | @node Separate Objdir |
| 24785 | @section Compiling @value{GDBN} in Another Directory |
| 24786 | |
| 24787 | If you want to run @value{GDBN} versions for several host or target machines, |
| 24788 | you need a different @code{gdb} compiled for each combination of |
| 24789 | host and target. @file{configure} is designed to make this easy by |
| 24790 | allowing you to generate each configuration in a separate subdirectory, |
| 24791 | rather than in the source directory. If your @code{make} program |
| 24792 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running |
| 24793 | @code{make} in each of these directories builds the @code{gdb} |
| 24794 | program specified there. |
| 24795 | |
| 24796 | To build @code{gdb} in a separate directory, run @file{configure} |
| 24797 | with the @samp{--srcdir} option to specify where to find the source. |
| 24798 | (You also need to specify a path to find @file{configure} |
| 24799 | itself from your working directory. If the path to @file{configure} |
| 24800 | would be the same as the argument to @samp{--srcdir}, you can leave out |
| 24801 | the @samp{--srcdir} option; it is assumed.) |
| 24802 | |
| 24803 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a |
| 24804 | separate directory for a Sun 4 like this: |
| 24805 | |
| 24806 | @smallexample |
| 24807 | @group |
| 24808 | cd gdb-@value{GDBVN} |
| 24809 | mkdir ../gdb-sun4 |
| 24810 | cd ../gdb-sun4 |
| 24811 | ../gdb-@value{GDBVN}/configure sun4 |
| 24812 | make |
| 24813 | @end group |
| 24814 | @end smallexample |
| 24815 | |
| 24816 | When @file{configure} builds a configuration using a remote source |
| 24817 | directory, it creates a tree for the binaries with the same structure |
| 24818 | (and using the same names) as the tree under the source directory. In |
| 24819 | the example, you'd find the Sun 4 library @file{libiberty.a} in the |
| 24820 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in |
| 24821 | @file{gdb-sun4/gdb}. |
| 24822 | |
| 24823 | Make sure that your path to the @file{configure} script has just one |
| 24824 | instance of @file{gdb} in it. If your path to @file{configure} looks |
| 24825 | like @file{../gdb-@value{GDBVN}/gdb/configure}, you are configuring only |
| 24826 | one subdirectory of @value{GDBN}, not the whole package. This leads to |
| 24827 | build errors about missing include files such as @file{bfd/bfd.h}. |
| 24828 | |
| 24829 | One popular reason to build several @value{GDBN} configurations in separate |
| 24830 | directories is to configure @value{GDBN} for cross-compiling (where |
| 24831 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging |
| 24832 | programs that run on another machine---the @dfn{target}). |
| 24833 | You specify a cross-debugging target by |
| 24834 | giving the @samp{--target=@var{target}} option to @file{configure}. |
| 24835 | |
| 24836 | When you run @code{make} to build a program or library, you must run |
| 24837 | it in a configured directory---whatever directory you were in when you |
| 24838 | called @file{configure} (or one of its subdirectories). |
| 24839 | |
| 24840 | The @code{Makefile} that @file{configure} generates in each source |
| 24841 | directory also runs recursively. If you type @code{make} in a source |
| 24842 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured |
| 24843 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you |
| 24844 | will build all the required libraries, and then build GDB. |
| 24845 | |
| 24846 | When you have multiple hosts or targets configured in separate |
| 24847 | directories, you can run @code{make} on them in parallel (for example, |
| 24848 | if they are NFS-mounted on each of the hosts); they will not interfere |
| 24849 | with each other. |
| 24850 | |
| 24851 | @node Config Names |
| 24852 | @section Specifying Names for Hosts and Targets |
| 24853 | |
| 24854 | The specifications used for hosts and targets in the @file{configure} |
| 24855 | script are based on a three-part naming scheme, but some short predefined |
| 24856 | aliases are also supported. The full naming scheme encodes three pieces |
| 24857 | of information in the following pattern: |
| 24858 | |
| 24859 | @smallexample |
| 24860 | @var{architecture}-@var{vendor}-@var{os} |
| 24861 | @end smallexample |
| 24862 | |
| 24863 | For example, you can use the alias @code{sun4} as a @var{host} argument, |
| 24864 | or as the value for @var{target} in a @code{--target=@var{target}} |
| 24865 | option. The equivalent full name is @samp{sparc-sun-sunos4}. |
| 24866 | |
| 24867 | The @file{configure} script accompanying @value{GDBN} does not provide |
| 24868 | any query facility to list all supported host and target names or |
| 24869 | aliases. @file{configure} calls the Bourne shell script |
| 24870 | @code{config.sub} to map abbreviations to full names; you can read the |
| 24871 | script, if you wish, or you can use it to test your guesses on |
| 24872 | abbreviations---for example: |
| 24873 | |
| 24874 | @smallexample |
| 24875 | % sh config.sub i386-linux |
| 24876 | i386-pc-linux-gnu |
| 24877 | % sh config.sub alpha-linux |
| 24878 | alpha-unknown-linux-gnu |
| 24879 | % sh config.sub hp9k700 |
| 24880 | hppa1.1-hp-hpux |
| 24881 | % sh config.sub sun4 |
| 24882 | sparc-sun-sunos4.1.1 |
| 24883 | % sh config.sub sun3 |
| 24884 | m68k-sun-sunos4.1.1 |
| 24885 | % sh config.sub i986v |
| 24886 | Invalid configuration `i986v': machine `i986v' not recognized |
| 24887 | @end smallexample |
| 24888 | |
| 24889 | @noindent |
| 24890 | @code{config.sub} is also distributed in the @value{GDBN} source |
| 24891 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). |
| 24892 | |
| 24893 | @node Configure Options |
| 24894 | @section @file{configure} Options |
| 24895 | |
| 24896 | Here is a summary of the @file{configure} options and arguments that |
| 24897 | are most often useful for building @value{GDBN}. @file{configure} also has |
| 24898 | several other options not listed here. @inforef{What Configure |
| 24899 | Does,,configure.info}, for a full explanation of @file{configure}. |
| 24900 | |
| 24901 | @smallexample |
| 24902 | configure @r{[}--help@r{]} |
| 24903 | @r{[}--prefix=@var{dir}@r{]} |
| 24904 | @r{[}--exec-prefix=@var{dir}@r{]} |
| 24905 | @r{[}--srcdir=@var{dirname}@r{]} |
| 24906 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} |
| 24907 | @r{[}--target=@var{target}@r{]} |
| 24908 | @var{host} |
| 24909 | @end smallexample |
| 24910 | |
| 24911 | @noindent |
| 24912 | You may introduce options with a single @samp{-} rather than |
| 24913 | @samp{--} if you prefer; but you may abbreviate option names if you use |
| 24914 | @samp{--}. |
| 24915 | |
| 24916 | @table @code |
| 24917 | @item --help |
| 24918 | Display a quick summary of how to invoke @file{configure}. |
| 24919 | |
| 24920 | @item --prefix=@var{dir} |
| 24921 | Configure the source to install programs and files under directory |
| 24922 | @file{@var{dir}}. |
| 24923 | |
| 24924 | @item --exec-prefix=@var{dir} |
| 24925 | Configure the source to install programs under directory |
| 24926 | @file{@var{dir}}. |
| 24927 | |
| 24928 | @c avoid splitting the warning from the explanation: |
| 24929 | @need 2000 |
| 24930 | @item --srcdir=@var{dirname} |
| 24931 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another |
| 24932 | @code{make} that implements the @code{VPATH} feature.}@* |
| 24933 | Use this option to make configurations in directories separate from the |
| 24934 | @value{GDBN} source directories. Among other things, you can use this to |
| 24935 | build (or maintain) several configurations simultaneously, in separate |
| 24936 | directories. @file{configure} writes configuration-specific files in |
| 24937 | the current directory, but arranges for them to use the source in the |
| 24938 | directory @var{dirname}. @file{configure} creates directories under |
| 24939 | the working directory in parallel to the source directories below |
| 24940 | @var{dirname}. |
| 24941 | |
| 24942 | @item --norecursion |
| 24943 | Configure only the directory level where @file{configure} is executed; do not |
| 24944 | propagate configuration to subdirectories. |
| 24945 | |
| 24946 | @item --target=@var{target} |
| 24947 | Configure @value{GDBN} for cross-debugging programs running on the specified |
| 24948 | @var{target}. Without this option, @value{GDBN} is configured to debug |
| 24949 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. |
| 24950 | |
| 24951 | There is no convenient way to generate a list of all available targets. |
| 24952 | |
| 24953 | @item @var{host} @dots{} |
| 24954 | Configure @value{GDBN} to run on the specified @var{host}. |
| 24955 | |
| 24956 | There is no convenient way to generate a list of all available hosts. |
| 24957 | @end table |
| 24958 | |
| 24959 | There are many other options available as well, but they are generally |
| 24960 | needed for special purposes only. |
| 24961 | |
| 24962 | @node System-wide configuration |
| 24963 | @section System-wide configuration and settings |
| 24964 | @cindex system-wide init file |
| 24965 | |
| 24966 | @value{GDBN} can be configured to have a system-wide init file; |
| 24967 | this file will be read and executed at startup (@pxref{Startup, , What |
| 24968 | @value{GDBN} does during startup}). |
| 24969 | |
| 24970 | Here is the corresponding configure option: |
| 24971 | |
| 24972 | @table @code |
| 24973 | @item --with-system-gdbinit=@var{file} |
| 24974 | Specify that the default location of the system-wide init file is |
| 24975 | @var{file}. |
| 24976 | @end table |
| 24977 | |
| 24978 | If @value{GDBN} has been configured with the option @option{--prefix=$prefix}, |
| 24979 | it may be subject to relocation. Two possible cases: |
| 24980 | |
| 24981 | @itemize @bullet |
| 24982 | @item |
| 24983 | If the default location of this init file contains @file{$prefix}, |
| 24984 | it will be subject to relocation. Suppose that the configure options |
| 24985 | are @option{--prefix=$prefix --with-system-gdbinit=$prefix/etc/gdbinit}; |
| 24986 | if @value{GDBN} is moved from @file{$prefix} to @file{$install}, the system |
| 24987 | init file is looked for as @file{$install/etc/gdbinit} instead of |
| 24988 | @file{$prefix/etc/gdbinit}. |
| 24989 | |
| 24990 | @item |
| 24991 | By contrast, if the default location does not contain the prefix, |
| 24992 | it will not be relocated. E.g.@: if @value{GDBN} has been configured with |
| 24993 | @option{--prefix=/usr/local --with-system-gdbinit=/usr/share/gdb/gdbinit}, |
| 24994 | then @value{GDBN} will always look for @file{/usr/share/gdb/gdbinit}, |
| 24995 | wherever @value{GDBN} is installed. |
| 24996 | @end itemize |
| 24997 | |
| 24998 | @node Maintenance Commands |
| 24999 | @appendix Maintenance Commands |
| 25000 | @cindex maintenance commands |
| 25001 | @cindex internal commands |
| 25002 | |
| 25003 | In addition to commands intended for @value{GDBN} users, @value{GDBN} |
| 25004 | includes a number of commands intended for @value{GDBN} developers, |
| 25005 | that are not documented elsewhere in this manual. These commands are |
| 25006 | provided here for reference. (For commands that turn on debugging |
| 25007 | messages, see @ref{Debugging Output}.) |
| 25008 | |
| 25009 | @table @code |
| 25010 | @kindex maint agent |
| 25011 | @item maint agent @var{expression} |
| 25012 | Translate the given @var{expression} into remote agent bytecodes. |
| 25013 | This command is useful for debugging the Agent Expression mechanism |
| 25014 | (@pxref{Agent Expressions}). |
| 25015 | |
| 25016 | @kindex maint info breakpoints |
| 25017 | @item @anchor{maint info breakpoints}maint info breakpoints |
| 25018 | Using the same format as @samp{info breakpoints}, display both the |
| 25019 | breakpoints you've set explicitly, and those @value{GDBN} is using for |
| 25020 | internal purposes. Internal breakpoints are shown with negative |
| 25021 | breakpoint numbers. The type column identifies what kind of breakpoint |
| 25022 | is shown: |
| 25023 | |
| 25024 | @table @code |
| 25025 | @item breakpoint |
| 25026 | Normal, explicitly set breakpoint. |
| 25027 | |
| 25028 | @item watchpoint |
| 25029 | Normal, explicitly set watchpoint. |
| 25030 | |
| 25031 | @item longjmp |
| 25032 | Internal breakpoint, used to handle correctly stepping through |
| 25033 | @code{longjmp} calls. |
| 25034 | |
| 25035 | @item longjmp resume |
| 25036 | Internal breakpoint at the target of a @code{longjmp}. |
| 25037 | |
| 25038 | @item until |
| 25039 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. |
| 25040 | |
| 25041 | @item finish |
| 25042 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. |
| 25043 | |
| 25044 | @item shlib events |
| 25045 | Shared library events. |
| 25046 | |
| 25047 | @end table |
| 25048 | |
| 25049 | @kindex set displaced-stepping |
| 25050 | @kindex show displaced-stepping |
| 25051 | @cindex displaced stepping support |
| 25052 | @cindex out-of-line single-stepping |
| 25053 | @item set displaced-stepping |
| 25054 | @itemx show displaced-stepping |
| 25055 | Control whether or not @value{GDBN} will do @dfn{displaced stepping} |
| 25056 | if the target supports it. Displaced stepping is a way to single-step |
| 25057 | over breakpoints without removing them from the inferior, by executing |
| 25058 | an out-of-line copy of the instruction that was originally at the |
| 25059 | breakpoint location. It is also known as out-of-line single-stepping. |
| 25060 | |
| 25061 | @table @code |
| 25062 | @item set displaced-stepping on |
| 25063 | If the target architecture supports it, @value{GDBN} will use |
| 25064 | displaced stepping to step over breakpoints. |
| 25065 | |
| 25066 | @item set displaced-stepping off |
| 25067 | @value{GDBN} will not use displaced stepping to step over breakpoints, |
| 25068 | even if such is supported by the target architecture. |
| 25069 | |
| 25070 | @cindex non-stop mode, and @samp{set displaced-stepping} |
| 25071 | @item set displaced-stepping auto |
| 25072 | This is the default mode. @value{GDBN} will use displaced stepping |
| 25073 | only if non-stop mode is active (@pxref{Non-Stop Mode}) and the target |
| 25074 | architecture supports displaced stepping. |
| 25075 | @end table |
| 25076 | |
| 25077 | @kindex maint check-symtabs |
| 25078 | @item maint check-symtabs |
| 25079 | Check the consistency of psymtabs and symtabs. |
| 25080 | |
| 25081 | @kindex maint cplus first_component |
| 25082 | @item maint cplus first_component @var{name} |
| 25083 | Print the first C@t{++} class/namespace component of @var{name}. |
| 25084 | |
| 25085 | @kindex maint cplus namespace |
| 25086 | @item maint cplus namespace |
| 25087 | Print the list of possible C@t{++} namespaces. |
| 25088 | |
| 25089 | @kindex maint demangle |
| 25090 | @item maint demangle @var{name} |
| 25091 | Demangle a C@t{++} or Objective-C mangled @var{name}. |
| 25092 | |
| 25093 | @kindex maint deprecate |
| 25094 | @kindex maint undeprecate |
| 25095 | @cindex deprecated commands |
| 25096 | @item maint deprecate @var{command} @r{[}@var{replacement}@r{]} |
| 25097 | @itemx maint undeprecate @var{command} |
| 25098 | Deprecate or undeprecate the named @var{command}. Deprecated commands |
| 25099 | cause @value{GDBN} to issue a warning when you use them. The optional |
| 25100 | argument @var{replacement} says which newer command should be used in |
| 25101 | favor of the deprecated one; if it is given, @value{GDBN} will mention |
| 25102 | the replacement as part of the warning. |
| 25103 | |
| 25104 | @kindex maint dump-me |
| 25105 | @item maint dump-me |
| 25106 | @cindex @code{SIGQUIT} signal, dump core of @value{GDBN} |
| 25107 | Cause a fatal signal in the debugger and force it to dump its core. |
| 25108 | This is supported only on systems which support aborting a program |
| 25109 | with the @code{SIGQUIT} signal. |
| 25110 | |
| 25111 | @kindex maint internal-error |
| 25112 | @kindex maint internal-warning |
| 25113 | @item maint internal-error @r{[}@var{message-text}@r{]} |
| 25114 | @itemx maint internal-warning @r{[}@var{message-text}@r{]} |
| 25115 | Cause @value{GDBN} to call the internal function @code{internal_error} |
| 25116 | or @code{internal_warning} and hence behave as though an internal error |
| 25117 | or internal warning has been detected. In addition to reporting the |
| 25118 | internal problem, these functions give the user the opportunity to |
| 25119 | either quit @value{GDBN} or create a core file of the current |
| 25120 | @value{GDBN} session. |
| 25121 | |
| 25122 | These commands take an optional parameter @var{message-text} that is |
| 25123 | used as the text of the error or warning message. |
| 25124 | |
| 25125 | Here's an example of using @code{internal-error}: |
| 25126 | |
| 25127 | @smallexample |
| 25128 | (@value{GDBP}) @kbd{maint internal-error testing, 1, 2} |
| 25129 | @dots{}/maint.c:121: internal-error: testing, 1, 2 |
| 25130 | A problem internal to GDB has been detected. Further |
| 25131 | debugging may prove unreliable. |
| 25132 | Quit this debugging session? (y or n) @kbd{n} |
| 25133 | Create a core file? (y or n) @kbd{n} |
| 25134 | (@value{GDBP}) |
| 25135 | @end smallexample |
| 25136 | |
| 25137 | @cindex @value{GDBN} internal error |
| 25138 | @cindex internal errors, control of @value{GDBN} behavior |
| 25139 | |
| 25140 | @kindex maint set internal-error |
| 25141 | @kindex maint show internal-error |
| 25142 | @kindex maint set internal-warning |
| 25143 | @kindex maint show internal-warning |
| 25144 | @item maint set internal-error @var{action} [ask|yes|no] |
| 25145 | @itemx maint show internal-error @var{action} |
| 25146 | @itemx maint set internal-warning @var{action} [ask|yes|no] |
| 25147 | @itemx maint show internal-warning @var{action} |
| 25148 | When @value{GDBN} reports an internal problem (error or warning) it |
| 25149 | gives the user the opportunity to both quit @value{GDBN} and create a |
| 25150 | core file of the current @value{GDBN} session. These commands let you |
| 25151 | override the default behaviour for each particular @var{action}, |
| 25152 | described in the table below. |
| 25153 | |
| 25154 | @table @samp |
| 25155 | @item quit |
| 25156 | You can specify that @value{GDBN} should always (yes) or never (no) |
| 25157 | quit. The default is to ask the user what to do. |
| 25158 | |
| 25159 | @item corefile |
| 25160 | You can specify that @value{GDBN} should always (yes) or never (no) |
| 25161 | create a core file. The default is to ask the user what to do. |
| 25162 | @end table |
| 25163 | |
| 25164 | @kindex maint packet |
| 25165 | @item maint packet @var{text} |
| 25166 | If @value{GDBN} is talking to an inferior via the serial protocol, |
| 25167 | then this command sends the string @var{text} to the inferior, and |
| 25168 | displays the response packet. @value{GDBN} supplies the initial |
| 25169 | @samp{$} character, the terminating @samp{#} character, and the |
| 25170 | checksum. |
| 25171 | |
| 25172 | @kindex maint print architecture |
| 25173 | @item maint print architecture @r{[}@var{file}@r{]} |
| 25174 | Print the entire architecture configuration. The optional argument |
| 25175 | @var{file} names the file where the output goes. |
| 25176 | |
| 25177 | @kindex maint print c-tdesc |
| 25178 | @item maint print c-tdesc |
| 25179 | Print the current target description (@pxref{Target Descriptions}) as |
| 25180 | a C source file. The created source file can be used in @value{GDBN} |
| 25181 | when an XML parser is not available to parse the description. |
| 25182 | |
| 25183 | @kindex maint print dummy-frames |
| 25184 | @item maint print dummy-frames |
| 25185 | Prints the contents of @value{GDBN}'s internal dummy-frame stack. |
| 25186 | |
| 25187 | @smallexample |
| 25188 | (@value{GDBP}) @kbd{b add} |
| 25189 | @dots{} |
| 25190 | (@value{GDBP}) @kbd{print add(2,3)} |
| 25191 | Breakpoint 2, add (a=2, b=3) at @dots{} |
| 25192 | 58 return (a + b); |
| 25193 | The program being debugged stopped while in a function called from GDB. |
| 25194 | @dots{} |
| 25195 | (@value{GDBP}) @kbd{maint print dummy-frames} |
| 25196 | 0x1a57c80: pc=0x01014068 fp=0x0200bddc sp=0x0200bdd6 |
| 25197 | top=0x0200bdd4 id=@{stack=0x200bddc,code=0x101405c@} |
| 25198 | call_lo=0x01014000 call_hi=0x01014001 |
| 25199 | (@value{GDBP}) |
| 25200 | @end smallexample |
| 25201 | |
| 25202 | Takes an optional file parameter. |
| 25203 | |
| 25204 | @kindex maint print registers |
| 25205 | @kindex maint print raw-registers |
| 25206 | @kindex maint print cooked-registers |
| 25207 | @kindex maint print register-groups |
| 25208 | @item maint print registers @r{[}@var{file}@r{]} |
| 25209 | @itemx maint print raw-registers @r{[}@var{file}@r{]} |
| 25210 | @itemx maint print cooked-registers @r{[}@var{file}@r{]} |
| 25211 | @itemx maint print register-groups @r{[}@var{file}@r{]} |
| 25212 | Print @value{GDBN}'s internal register data structures. |
| 25213 | |
| 25214 | The command @code{maint print raw-registers} includes the contents of |
| 25215 | the raw register cache; the command @code{maint print cooked-registers} |
| 25216 | includes the (cooked) value of all registers; and the command |
| 25217 | @code{maint print register-groups} includes the groups that each |
| 25218 | register is a member of. @xref{Registers,, Registers, gdbint, |
| 25219 | @value{GDBN} Internals}. |
| 25220 | |
| 25221 | These commands take an optional parameter, a file name to which to |
| 25222 | write the information. |
| 25223 | |
| 25224 | @kindex maint print reggroups |
| 25225 | @item maint print reggroups @r{[}@var{file}@r{]} |
| 25226 | Print @value{GDBN}'s internal register group data structures. The |
| 25227 | optional argument @var{file} tells to what file to write the |
| 25228 | information. |
| 25229 | |
| 25230 | The register groups info looks like this: |
| 25231 | |
| 25232 | @smallexample |
| 25233 | (@value{GDBP}) @kbd{maint print reggroups} |
| 25234 | Group Type |
| 25235 | general user |
| 25236 | float user |
| 25237 | all user |
| 25238 | vector user |
| 25239 | system user |
| 25240 | save internal |
| 25241 | restore internal |
| 25242 | @end smallexample |
| 25243 | |
| 25244 | @kindex flushregs |
| 25245 | @item flushregs |
| 25246 | This command forces @value{GDBN} to flush its internal register cache. |
| 25247 | |
| 25248 | @kindex maint print objfiles |
| 25249 | @cindex info for known object files |
| 25250 | @item maint print objfiles |
| 25251 | Print a dump of all known object files. For each object file, this |
| 25252 | command prints its name, address in memory, and all of its psymtabs |
| 25253 | and symtabs. |
| 25254 | |
| 25255 | @kindex maint print statistics |
| 25256 | @cindex bcache statistics |
| 25257 | @item maint print statistics |
| 25258 | This command prints, for each object file in the program, various data |
| 25259 | about that object file followed by the byte cache (@dfn{bcache}) |
| 25260 | statistics for the object file. The objfile data includes the number |
| 25261 | of minimal, partial, full, and stabs symbols, the number of types |
| 25262 | defined by the objfile, the number of as yet unexpanded psym tables, |
| 25263 | the number of line tables and string tables, and the amount of memory |
| 25264 | used by the various tables. The bcache statistics include the counts, |
| 25265 | sizes, and counts of duplicates of all and unique objects, max, |
| 25266 | average, and median entry size, total memory used and its overhead and |
| 25267 | savings, and various measures of the hash table size and chain |
| 25268 | lengths. |
| 25269 | |
| 25270 | @kindex maint print target-stack |
| 25271 | @cindex target stack description |
| 25272 | @item maint print target-stack |
| 25273 | A @dfn{target} is an interface between the debugger and a particular |
| 25274 | kind of file or process. Targets can be stacked in @dfn{strata}, |
| 25275 | so that more than one target can potentially respond to a request. |
| 25276 | In particular, memory accesses will walk down the stack of targets |
| 25277 | until they find a target that is interested in handling that particular |
| 25278 | address. |
| 25279 | |
| 25280 | This command prints a short description of each layer that was pushed on |
| 25281 | the @dfn{target stack}, starting from the top layer down to the bottom one. |
| 25282 | |
| 25283 | @kindex maint print type |
| 25284 | @cindex type chain of a data type |
| 25285 | @item maint print type @var{expr} |
| 25286 | Print the type chain for a type specified by @var{expr}. The argument |
| 25287 | can be either a type name or a symbol. If it is a symbol, the type of |
| 25288 | that symbol is described. The type chain produced by this command is |
| 25289 | a recursive definition of the data type as stored in @value{GDBN}'s |
| 25290 | data structures, including its flags and contained types. |
| 25291 | |
| 25292 | @kindex maint set dwarf2 max-cache-age |
| 25293 | @kindex maint show dwarf2 max-cache-age |
| 25294 | @item maint set dwarf2 max-cache-age |
| 25295 | @itemx maint show dwarf2 max-cache-age |
| 25296 | Control the DWARF 2 compilation unit cache. |
| 25297 | |
| 25298 | @cindex DWARF 2 compilation units cache |
| 25299 | In object files with inter-compilation-unit references, such as those |
| 25300 | produced by the GCC option @samp{-feliminate-dwarf2-dups}, the DWARF 2 |
| 25301 | reader needs to frequently refer to previously read compilation units. |
| 25302 | This setting controls how long a compilation unit will remain in the |
| 25303 | cache if it is not referenced. A higher limit means that cached |
| 25304 | compilation units will be stored in memory longer, and more total |
| 25305 | memory will be used. Setting it to zero disables caching, which will |
| 25306 | slow down @value{GDBN} startup, but reduce memory consumption. |
| 25307 | |
| 25308 | @kindex maint set profile |
| 25309 | @kindex maint show profile |
| 25310 | @cindex profiling GDB |
| 25311 | @item maint set profile |
| 25312 | @itemx maint show profile |
| 25313 | Control profiling of @value{GDBN}. |
| 25314 | |
| 25315 | Profiling will be disabled until you use the @samp{maint set profile} |
| 25316 | command to enable it. When you enable profiling, the system will begin |
| 25317 | collecting timing and execution count data; when you disable profiling or |
| 25318 | exit @value{GDBN}, the results will be written to a log file. Remember that |
| 25319 | if you use profiling, @value{GDBN} will overwrite the profiling log file |
| 25320 | (often called @file{gmon.out}). If you have a record of important profiling |
| 25321 | data in a @file{gmon.out} file, be sure to move it to a safe location. |
| 25322 | |
| 25323 | Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be |
| 25324 | compiled with the @samp{-pg} compiler option. |
| 25325 | |
| 25326 | @kindex maint set linux-async |
| 25327 | @kindex maint show linux-async |
| 25328 | @cindex asynchronous support |
| 25329 | @item maint set linux-async |
| 25330 | @itemx maint show linux-async |
| 25331 | Control the GNU/Linux native asynchronous support |
| 25332 | (@pxref{Background Execution}) of @value{GDBN}. |
| 25333 | |
| 25334 | GNU/Linux native asynchronous support will be disabled until you use |
| 25335 | the @samp{maint set linux-async} command to enable it. |
| 25336 | |
| 25337 | @kindex maint set remote-async |
| 25338 | @kindex maint show remote-async |
| 25339 | @cindex asynchronous support |
| 25340 | @item maint set remote-async |
| 25341 | @itemx maint show remote-async |
| 25342 | Control the remote asynchronous support |
| 25343 | (@pxref{Background Execution}) of @value{GDBN}. |
| 25344 | |
| 25345 | Remote asynchronous support will be disabled until you use |
| 25346 | the @samp{maint set remote-async} command to enable it. |
| 25347 | |
| 25348 | @kindex maint show-debug-regs |
| 25349 | @cindex x86 hardware debug registers |
| 25350 | @item maint show-debug-regs |
| 25351 | Control whether to show variables that mirror the x86 hardware debug |
| 25352 | registers. Use @code{ON} to enable, @code{OFF} to disable. If |
| 25353 | enabled, the debug registers values are shown when @value{GDBN} inserts or |
| 25354 | removes a hardware breakpoint or watchpoint, and when the inferior |
| 25355 | triggers a hardware-assisted breakpoint or watchpoint. |
| 25356 | |
| 25357 | @kindex maint space |
| 25358 | @cindex memory used by commands |
| 25359 | @item maint space |
| 25360 | Control whether to display memory usage for each command. If set to a |
| 25361 | nonzero value, @value{GDBN} will display how much memory each command |
| 25362 | took, following the command's own output. This can also be requested |
| 25363 | by invoking @value{GDBN} with the @option{--statistics} command-line |
| 25364 | switch (@pxref{Mode Options}). |
| 25365 | |
| 25366 | @kindex maint time |
| 25367 | @cindex time of command execution |
| 25368 | @item maint time |
| 25369 | Control whether to display the execution time for each command. If |
| 25370 | set to a nonzero value, @value{GDBN} will display how much time it |
| 25371 | took to execute each command, following the command's own output. |
| 25372 | The time is not printed for the commands that run the target, since |
| 25373 | there's no mechanism currently to compute how much time was spend |
| 25374 | by @value{GDBN} and how much time was spend by the program been debugged. |
| 25375 | it's not possibly currently |
| 25376 | This can also be requested by invoking @value{GDBN} with the |
| 25377 | @option{--statistics} command-line switch (@pxref{Mode Options}). |
| 25378 | |
| 25379 | @kindex maint translate-address |
| 25380 | @item maint translate-address @r{[}@var{section}@r{]} @var{addr} |
| 25381 | Find the symbol stored at the location specified by the address |
| 25382 | @var{addr} and an optional section name @var{section}. If found, |
| 25383 | @value{GDBN} prints the name of the closest symbol and an offset from |
| 25384 | the symbol's location to the specified address. This is similar to |
| 25385 | the @code{info address} command (@pxref{Symbols}), except that this |
| 25386 | command also allows to find symbols in other sections. |
| 25387 | |
| 25388 | If section was not specified, the section in which the symbol was found |
| 25389 | is also printed. For dynamically linked executables, the name of |
| 25390 | executable or shared library containing the symbol is printed as well. |
| 25391 | |
| 25392 | @end table |
| 25393 | |
| 25394 | The following command is useful for non-interactive invocations of |
| 25395 | @value{GDBN}, such as in the test suite. |
| 25396 | |
| 25397 | @table @code |
| 25398 | @item set watchdog @var{nsec} |
| 25399 | @kindex set watchdog |
| 25400 | @cindex watchdog timer |
| 25401 | @cindex timeout for commands |
| 25402 | Set the maximum number of seconds @value{GDBN} will wait for the |
| 25403 | target operation to finish. If this time expires, @value{GDBN} |
| 25404 | reports and error and the command is aborted. |
| 25405 | |
| 25406 | @item show watchdog |
| 25407 | Show the current setting of the target wait timeout. |
| 25408 | @end table |
| 25409 | |
| 25410 | @node Remote Protocol |
| 25411 | @appendix @value{GDBN} Remote Serial Protocol |
| 25412 | |
| 25413 | @menu |
| 25414 | * Overview:: |
| 25415 | * Packets:: |
| 25416 | * Stop Reply Packets:: |
| 25417 | * General Query Packets:: |
| 25418 | * Register Packet Format:: |
| 25419 | * Tracepoint Packets:: |
| 25420 | * Host I/O Packets:: |
| 25421 | * Interrupts:: |
| 25422 | * Notification Packets:: |
| 25423 | * Remote Non-Stop:: |
| 25424 | * Packet Acknowledgment:: |
| 25425 | * Examples:: |
| 25426 | * File-I/O Remote Protocol Extension:: |
| 25427 | * Library List Format:: |
| 25428 | * Memory Map Format:: |
| 25429 | @end menu |
| 25430 | |
| 25431 | @node Overview |
| 25432 | @section Overview |
| 25433 | |
| 25434 | There may be occasions when you need to know something about the |
| 25435 | protocol---for example, if there is only one serial port to your target |
| 25436 | machine, you might want your program to do something special if it |
| 25437 | recognizes a packet meant for @value{GDBN}. |
| 25438 | |
| 25439 | In the examples below, @samp{->} and @samp{<-} are used to indicate |
| 25440 | transmitted and received data, respectively. |
| 25441 | |
| 25442 | @cindex protocol, @value{GDBN} remote serial |
| 25443 | @cindex serial protocol, @value{GDBN} remote |
| 25444 | @cindex remote serial protocol |
| 25445 | All @value{GDBN} commands and responses (other than acknowledgments |
| 25446 | and notifications, see @ref{Notification Packets}) are sent as a |
| 25447 | @var{packet}. A @var{packet} is introduced with the character |
| 25448 | @samp{$}, the actual @var{packet-data}, and the terminating character |
| 25449 | @samp{#} followed by a two-digit @var{checksum}: |
| 25450 | |
| 25451 | @smallexample |
| 25452 | @code{$}@var{packet-data}@code{#}@var{checksum} |
| 25453 | @end smallexample |
| 25454 | @noindent |
| 25455 | |
| 25456 | @cindex checksum, for @value{GDBN} remote |
| 25457 | @noindent |
| 25458 | The two-digit @var{checksum} is computed as the modulo 256 sum of all |
| 25459 | characters between the leading @samp{$} and the trailing @samp{#} (an |
| 25460 | eight bit unsigned checksum). |
| 25461 | |
| 25462 | Implementors should note that prior to @value{GDBN} 5.0 the protocol |
| 25463 | specification also included an optional two-digit @var{sequence-id}: |
| 25464 | |
| 25465 | @smallexample |
| 25466 | @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} |
| 25467 | @end smallexample |
| 25468 | |
| 25469 | @cindex sequence-id, for @value{GDBN} remote |
| 25470 | @noindent |
| 25471 | That @var{sequence-id} was appended to the acknowledgment. @value{GDBN} |
| 25472 | has never output @var{sequence-id}s. Stubs that handle packets added |
| 25473 | since @value{GDBN} 5.0 must not accept @var{sequence-id}. |
| 25474 | |
| 25475 | When either the host or the target machine receives a packet, the first |
| 25476 | response expected is an acknowledgment: either @samp{+} (to indicate |
| 25477 | the package was received correctly) or @samp{-} (to request |
| 25478 | retransmission): |
| 25479 | |
| 25480 | @smallexample |
| 25481 | -> @code{$}@var{packet-data}@code{#}@var{checksum} |
| 25482 | <- @code{+} |
| 25483 | @end smallexample |
| 25484 | @noindent |
| 25485 | |
| 25486 | The @samp{+}/@samp{-} acknowledgments can be disabled |
| 25487 | once a connection is established. |
| 25488 | @xref{Packet Acknowledgment}, for details. |
| 25489 | |
| 25490 | The host (@value{GDBN}) sends @var{command}s, and the target (the |
| 25491 | debugging stub incorporated in your program) sends a @var{response}. In |
| 25492 | the case of step and continue @var{command}s, the response is only sent |
| 25493 | when the operation has completed, and the target has again stopped all |
| 25494 | threads in all attached processes. This is the default all-stop mode |
| 25495 | behavior, but the remote protocol also supports @value{GDBN}'s non-stop |
| 25496 | execution mode; see @ref{Remote Non-Stop}, for details. |
| 25497 | |
| 25498 | @var{packet-data} consists of a sequence of characters with the |
| 25499 | exception of @samp{#} and @samp{$} (see @samp{X} packet for additional |
| 25500 | exceptions). |
| 25501 | |
| 25502 | @cindex remote protocol, field separator |
| 25503 | Fields within the packet should be separated using @samp{,} @samp{;} or |
| 25504 | @samp{:}. Except where otherwise noted all numbers are represented in |
| 25505 | @sc{hex} with leading zeros suppressed. |
| 25506 | |
| 25507 | Implementors should note that prior to @value{GDBN} 5.0, the character |
| 25508 | @samp{:} could not appear as the third character in a packet (as it |
| 25509 | would potentially conflict with the @var{sequence-id}). |
| 25510 | |
| 25511 | @cindex remote protocol, binary data |
| 25512 | @anchor{Binary Data} |
| 25513 | Binary data in most packets is encoded either as two hexadecimal |
| 25514 | digits per byte of binary data. This allowed the traditional remote |
| 25515 | protocol to work over connections which were only seven-bit clean. |
| 25516 | Some packets designed more recently assume an eight-bit clean |
| 25517 | connection, and use a more efficient encoding to send and receive |
| 25518 | binary data. |
| 25519 | |
| 25520 | The binary data representation uses @code{7d} (@sc{ascii} @samp{@}}) |
| 25521 | as an escape character. Any escaped byte is transmitted as the escape |
| 25522 | character followed by the original character XORed with @code{0x20}. |
| 25523 | For example, the byte @code{0x7d} would be transmitted as the two |
| 25524 | bytes @code{0x7d 0x5d}. The bytes @code{0x23} (@sc{ascii} @samp{#}), |
| 25525 | @code{0x24} (@sc{ascii} @samp{$}), and @code{0x7d} (@sc{ascii} |
| 25526 | @samp{@}}) must always be escaped. Responses sent by the stub |
| 25527 | must also escape @code{0x2a} (@sc{ascii} @samp{*}), so that it |
| 25528 | is not interpreted as the start of a run-length encoded sequence |
| 25529 | (described next). |
| 25530 | |
| 25531 | Response @var{data} can be run-length encoded to save space. |
| 25532 | Run-length encoding replaces runs of identical characters with one |
| 25533 | instance of the repeated character, followed by a @samp{*} and a |
| 25534 | repeat count. The repeat count is itself sent encoded, to avoid |
| 25535 | binary characters in @var{data}: a value of @var{n} is sent as |
| 25536 | @code{@var{n}+29}. For a repeat count greater or equal to 3, this |
| 25537 | produces a printable @sc{ascii} character, e.g.@: a space (@sc{ascii} |
| 25538 | code 32) for a repeat count of 3. (This is because run-length |
| 25539 | encoding starts to win for counts 3 or more.) Thus, for example, |
| 25540 | @samp{0* } is a run-length encoding of ``0000'': the space character |
| 25541 | after @samp{*} means repeat the leading @code{0} @w{@code{32 - 29 = |
| 25542 | 3}} more times. |
| 25543 | |
| 25544 | The printable characters @samp{#} and @samp{$} or with a numeric value |
| 25545 | greater than 126 must not be used. Runs of six repeats (@samp{#}) or |
| 25546 | seven repeats (@samp{$}) can be expanded using a repeat count of only |
| 25547 | five (@samp{"}). For example, @samp{00000000} can be encoded as |
| 25548 | @samp{0*"00}. |
| 25549 | |
| 25550 | The error response returned for some packets includes a two character |
| 25551 | error number. That number is not well defined. |
| 25552 | |
| 25553 | @cindex empty response, for unsupported packets |
| 25554 | For any @var{command} not supported by the stub, an empty response |
| 25555 | (@samp{$#00}) should be returned. That way it is possible to extend the |
| 25556 | protocol. A newer @value{GDBN} can tell if a packet is supported based |
| 25557 | on that response. |
| 25558 | |
| 25559 | A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M}, |
| 25560 | @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are |
| 25561 | optional. |
| 25562 | |
| 25563 | @node Packets |
| 25564 | @section Packets |
| 25565 | |
| 25566 | The following table provides a complete list of all currently defined |
| 25567 | @var{command}s and their corresponding response @var{data}. |
| 25568 | @xref{File-I/O Remote Protocol Extension}, for details about the File |
| 25569 | I/O extension of the remote protocol. |
| 25570 | |
| 25571 | Each packet's description has a template showing the packet's overall |
| 25572 | syntax, followed by an explanation of the packet's meaning. We |
| 25573 | include spaces in some of the templates for clarity; these are not |
| 25574 | part of the packet's syntax. No @value{GDBN} packet uses spaces to |
| 25575 | separate its components. For example, a template like @samp{foo |
| 25576 | @var{bar} @var{baz}} describes a packet beginning with the three ASCII |
| 25577 | bytes @samp{foo}, followed by a @var{bar}, followed directly by a |
| 25578 | @var{baz}. @value{GDBN} does not transmit a space character between the |
| 25579 | @samp{foo} and the @var{bar}, or between the @var{bar} and the |
| 25580 | @var{baz}. |
| 25581 | |
| 25582 | @cindex @var{thread-id}, in remote protocol |
| 25583 | @anchor{thread-id syntax} |
| 25584 | Several packets and replies include a @var{thread-id} field to identify |
| 25585 | a thread. Normally these are positive numbers with a target-specific |
| 25586 | interpretation, formatted as big-endian hex strings. A @var{thread-id} |
| 25587 | can also be a literal @samp{-1} to indicate all threads, or @samp{0} to |
| 25588 | pick any thread. |
| 25589 | |
| 25590 | In addition, the remote protocol supports a multiprocess feature in |
| 25591 | which the @var{thread-id} syntax is extended to optionally include both |
| 25592 | process and thread ID fields, as @samp{p@var{pid}.@var{tid}}. |
| 25593 | The @var{pid} (process) and @var{tid} (thread) components each have the |
| 25594 | format described above: a positive number with target-specific |
| 25595 | interpretation formatted as a big-endian hex string, literal @samp{-1} |
| 25596 | to indicate all processes or threads (respectively), or @samp{0} to |
| 25597 | indicate an arbitrary process or thread. Specifying just a process, as |
| 25598 | @samp{p@var{pid}}, is equivalent to @samp{p@var{pid}.-1}. It is an |
| 25599 | error to specify all processes but a specific thread, such as |
| 25600 | @samp{p-1.@var{tid}}. Note that the @samp{p} prefix is @emph{not} used |
| 25601 | for those packets and replies explicitly documented to include a process |
| 25602 | ID, rather than a @var{thread-id}. |
| 25603 | |
| 25604 | The multiprocess @var{thread-id} syntax extensions are only used if both |
| 25605 | @value{GDBN} and the stub report support for the @samp{multiprocess} |
| 25606 | feature using @samp{qSupported}. @xref{multiprocess extensions}, for |
| 25607 | more information. |
| 25608 | |
| 25609 | Note that all packet forms beginning with an upper- or lower-case |
| 25610 | letter, other than those described here, are reserved for future use. |
| 25611 | |
| 25612 | Here are the packet descriptions. |
| 25613 | |
| 25614 | @table @samp |
| 25615 | |
| 25616 | @item ! |
| 25617 | @cindex @samp{!} packet |
| 25618 | @anchor{extended mode} |
| 25619 | Enable extended mode. In extended mode, the remote server is made |
| 25620 | persistent. The @samp{R} packet is used to restart the program being |
| 25621 | debugged. |
| 25622 | |
| 25623 | Reply: |
| 25624 | @table @samp |
| 25625 | @item OK |
| 25626 | The remote target both supports and has enabled extended mode. |
| 25627 | @end table |
| 25628 | |
| 25629 | @item ? |
| 25630 | @cindex @samp{?} packet |
| 25631 | Indicate the reason the target halted. The reply is the same as for |
| 25632 | step and continue. This packet has a special interpretation when the |
| 25633 | target is in non-stop mode; see @ref{Remote Non-Stop}. |
| 25634 | |
| 25635 | Reply: |
| 25636 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25637 | |
| 25638 | @item A @var{arglen},@var{argnum},@var{arg},@dots{} |
| 25639 | @cindex @samp{A} packet |
| 25640 | Initialized @code{argv[]} array passed into program. @var{arglen} |
| 25641 | specifies the number of bytes in the hex encoded byte stream |
| 25642 | @var{arg}. See @code{gdbserver} for more details. |
| 25643 | |
| 25644 | Reply: |
| 25645 | @table @samp |
| 25646 | @item OK |
| 25647 | The arguments were set. |
| 25648 | @item E @var{NN} |
| 25649 | An error occurred. |
| 25650 | @end table |
| 25651 | |
| 25652 | @item b @var{baud} |
| 25653 | @cindex @samp{b} packet |
| 25654 | (Don't use this packet; its behavior is not well-defined.) |
| 25655 | Change the serial line speed to @var{baud}. |
| 25656 | |
| 25657 | JTC: @emph{When does the transport layer state change? When it's |
| 25658 | received, or after the ACK is transmitted. In either case, there are |
| 25659 | problems if the command or the acknowledgment packet is dropped.} |
| 25660 | |
| 25661 | Stan: @emph{If people really wanted to add something like this, and get |
| 25662 | it working for the first time, they ought to modify ser-unix.c to send |
| 25663 | some kind of out-of-band message to a specially-setup stub and have the |
| 25664 | switch happen "in between" packets, so that from remote protocol's point |
| 25665 | of view, nothing actually happened.} |
| 25666 | |
| 25667 | @item B @var{addr},@var{mode} |
| 25668 | @cindex @samp{B} packet |
| 25669 | Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a |
| 25670 | breakpoint at @var{addr}. |
| 25671 | |
| 25672 | Don't use this packet. Use the @samp{Z} and @samp{z} packets instead |
| 25673 | (@pxref{insert breakpoint or watchpoint packet}). |
| 25674 | |
| 25675 | @item bc |
| 25676 | @cindex @samp{bc} packet |
| 25677 | Backward continue. Execute the target system in reverse. No parameter. |
| 25678 | @xref{Reverse Execution}, for more information. |
| 25679 | |
| 25680 | Reply: |
| 25681 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25682 | |
| 25683 | @item bs |
| 25684 | @cindex @samp{bs} packet |
| 25685 | Backward single step. Execute one instruction in reverse. No parameter. |
| 25686 | @xref{Reverse Execution}, for more information. |
| 25687 | |
| 25688 | Reply: |
| 25689 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25690 | |
| 25691 | @item c @r{[}@var{addr}@r{]} |
| 25692 | @cindex @samp{c} packet |
| 25693 | Continue. @var{addr} is address to resume. If @var{addr} is omitted, |
| 25694 | resume at current address. |
| 25695 | |
| 25696 | Reply: |
| 25697 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25698 | |
| 25699 | @item C @var{sig}@r{[};@var{addr}@r{]} |
| 25700 | @cindex @samp{C} packet |
| 25701 | Continue with signal @var{sig} (hex signal number). If |
| 25702 | @samp{;@var{addr}} is omitted, resume at same address. |
| 25703 | |
| 25704 | Reply: |
| 25705 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25706 | |
| 25707 | @item d |
| 25708 | @cindex @samp{d} packet |
| 25709 | Toggle debug flag. |
| 25710 | |
| 25711 | Don't use this packet; instead, define a general set packet |
| 25712 | (@pxref{General Query Packets}). |
| 25713 | |
| 25714 | @item D |
| 25715 | @itemx D;@var{pid} |
| 25716 | @cindex @samp{D} packet |
| 25717 | The first form of the packet is used to detach @value{GDBN} from the |
| 25718 | remote system. It is sent to the remote target |
| 25719 | before @value{GDBN} disconnects via the @code{detach} command. |
| 25720 | |
| 25721 | The second form, including a process ID, is used when multiprocess |
| 25722 | protocol extensions are enabled (@pxref{multiprocess extensions}), to |
| 25723 | detach only a specific process. The @var{pid} is specified as a |
| 25724 | big-endian hex string. |
| 25725 | |
| 25726 | Reply: |
| 25727 | @table @samp |
| 25728 | @item OK |
| 25729 | for success |
| 25730 | @item E @var{NN} |
| 25731 | for an error |
| 25732 | @end table |
| 25733 | |
| 25734 | @item F @var{RC},@var{EE},@var{CF};@var{XX} |
| 25735 | @cindex @samp{F} packet |
| 25736 | A reply from @value{GDBN} to an @samp{F} packet sent by the target. |
| 25737 | This is part of the File-I/O protocol extension. @xref{File-I/O |
| 25738 | Remote Protocol Extension}, for the specification. |
| 25739 | |
| 25740 | @item g |
| 25741 | @anchor{read registers packet} |
| 25742 | @cindex @samp{g} packet |
| 25743 | Read general registers. |
| 25744 | |
| 25745 | Reply: |
| 25746 | @table @samp |
| 25747 | @item @var{XX@dots{}} |
| 25748 | Each byte of register data is described by two hex digits. The bytes |
| 25749 | with the register are transmitted in target byte order. The size of |
| 25750 | each register and their position within the @samp{g} packet are |
| 25751 | determined by the @value{GDBN} internal gdbarch functions |
| 25752 | @code{DEPRECATED_REGISTER_RAW_SIZE} and @code{gdbarch_register_name}. The |
| 25753 | specification of several standard @samp{g} packets is specified below. |
| 25754 | @item E @var{NN} |
| 25755 | for an error. |
| 25756 | @end table |
| 25757 | |
| 25758 | @item G @var{XX@dots{}} |
| 25759 | @cindex @samp{G} packet |
| 25760 | Write general registers. @xref{read registers packet}, for a |
| 25761 | description of the @var{XX@dots{}} data. |
| 25762 | |
| 25763 | Reply: |
| 25764 | @table @samp |
| 25765 | @item OK |
| 25766 | for success |
| 25767 | @item E @var{NN} |
| 25768 | for an error |
| 25769 | @end table |
| 25770 | |
| 25771 | @item H @var{c} @var{thread-id} |
| 25772 | @cindex @samp{H} packet |
| 25773 | Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, |
| 25774 | @samp{G}, et.al.). @var{c} depends on the operation to be performed: it |
| 25775 | should be @samp{c} for step and continue operations, @samp{g} for other |
| 25776 | operations. The thread designator @var{thread-id} has the format and |
| 25777 | interpretation described in @ref{thread-id syntax}. |
| 25778 | |
| 25779 | Reply: |
| 25780 | @table @samp |
| 25781 | @item OK |
| 25782 | for success |
| 25783 | @item E @var{NN} |
| 25784 | for an error |
| 25785 | @end table |
| 25786 | |
| 25787 | @c FIXME: JTC: |
| 25788 | @c 'H': How restrictive (or permissive) is the thread model. If a |
| 25789 | @c thread is selected and stopped, are other threads allowed |
| 25790 | @c to continue to execute? As I mentioned above, I think the |
| 25791 | @c semantics of each command when a thread is selected must be |
| 25792 | @c described. For example: |
| 25793 | @c |
| 25794 | @c 'g': If the stub supports threads and a specific thread is |
| 25795 | @c selected, returns the register block from that thread; |
| 25796 | @c otherwise returns current registers. |
| 25797 | @c |
| 25798 | @c 'G' If the stub supports threads and a specific thread is |
| 25799 | @c selected, sets the registers of the register block of |
| 25800 | @c that thread; otherwise sets current registers. |
| 25801 | |
| 25802 | @item i @r{[}@var{addr}@r{[},@var{nnn}@r{]]} |
| 25803 | @anchor{cycle step packet} |
| 25804 | @cindex @samp{i} packet |
| 25805 | Step the remote target by a single clock cycle. If @samp{,@var{nnn}} is |
| 25806 | present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle |
| 25807 | step starting at that address. |
| 25808 | |
| 25809 | @item I |
| 25810 | @cindex @samp{I} packet |
| 25811 | Signal, then cycle step. @xref{step with signal packet}. @xref{cycle |
| 25812 | step packet}. |
| 25813 | |
| 25814 | @item k |
| 25815 | @cindex @samp{k} packet |
| 25816 | Kill request. |
| 25817 | |
| 25818 | FIXME: @emph{There is no description of how to operate when a specific |
| 25819 | thread context has been selected (i.e.@: does 'k' kill only that |
| 25820 | thread?)}. |
| 25821 | |
| 25822 | @item m @var{addr},@var{length} |
| 25823 | @cindex @samp{m} packet |
| 25824 | Read @var{length} bytes of memory starting at address @var{addr}. |
| 25825 | Note that @var{addr} may not be aligned to any particular boundary. |
| 25826 | |
| 25827 | The stub need not use any particular size or alignment when gathering |
| 25828 | data from memory for the response; even if @var{addr} is word-aligned |
| 25829 | and @var{length} is a multiple of the word size, the stub is free to |
| 25830 | use byte accesses, or not. For this reason, this packet may not be |
| 25831 | suitable for accessing memory-mapped I/O devices. |
| 25832 | @cindex alignment of remote memory accesses |
| 25833 | @cindex size of remote memory accesses |
| 25834 | @cindex memory, alignment and size of remote accesses |
| 25835 | |
| 25836 | Reply: |
| 25837 | @table @samp |
| 25838 | @item @var{XX@dots{}} |
| 25839 | Memory contents; each byte is transmitted as a two-digit hexadecimal |
| 25840 | number. The reply may contain fewer bytes than requested if the |
| 25841 | server was able to read only part of the region of memory. |
| 25842 | @item E @var{NN} |
| 25843 | @var{NN} is errno |
| 25844 | @end table |
| 25845 | |
| 25846 | @item M @var{addr},@var{length}:@var{XX@dots{}} |
| 25847 | @cindex @samp{M} packet |
| 25848 | Write @var{length} bytes of memory starting at address @var{addr}. |
| 25849 | @var{XX@dots{}} is the data; each byte is transmitted as a two-digit |
| 25850 | hexadecimal number. |
| 25851 | |
| 25852 | Reply: |
| 25853 | @table @samp |
| 25854 | @item OK |
| 25855 | for success |
| 25856 | @item E @var{NN} |
| 25857 | for an error (this includes the case where only part of the data was |
| 25858 | written). |
| 25859 | @end table |
| 25860 | |
| 25861 | @item p @var{n} |
| 25862 | @cindex @samp{p} packet |
| 25863 | Read the value of register @var{n}; @var{n} is in hex. |
| 25864 | @xref{read registers packet}, for a description of how the returned |
| 25865 | register value is encoded. |
| 25866 | |
| 25867 | Reply: |
| 25868 | @table @samp |
| 25869 | @item @var{XX@dots{}} |
| 25870 | the register's value |
| 25871 | @item E @var{NN} |
| 25872 | for an error |
| 25873 | @item |
| 25874 | Indicating an unrecognized @var{query}. |
| 25875 | @end table |
| 25876 | |
| 25877 | @item P @var{n@dots{}}=@var{r@dots{}} |
| 25878 | @anchor{write register packet} |
| 25879 | @cindex @samp{P} packet |
| 25880 | Write register @var{n@dots{}} with value @var{r@dots{}}. The register |
| 25881 | number @var{n} is in hexadecimal, and @var{r@dots{}} contains two hex |
| 25882 | digits for each byte in the register (target byte order). |
| 25883 | |
| 25884 | Reply: |
| 25885 | @table @samp |
| 25886 | @item OK |
| 25887 | for success |
| 25888 | @item E @var{NN} |
| 25889 | for an error |
| 25890 | @end table |
| 25891 | |
| 25892 | @item q @var{name} @var{params}@dots{} |
| 25893 | @itemx Q @var{name} @var{params}@dots{} |
| 25894 | @cindex @samp{q} packet |
| 25895 | @cindex @samp{Q} packet |
| 25896 | General query (@samp{q}) and set (@samp{Q}). These packets are |
| 25897 | described fully in @ref{General Query Packets}. |
| 25898 | |
| 25899 | @item r |
| 25900 | @cindex @samp{r} packet |
| 25901 | Reset the entire system. |
| 25902 | |
| 25903 | Don't use this packet; use the @samp{R} packet instead. |
| 25904 | |
| 25905 | @item R @var{XX} |
| 25906 | @cindex @samp{R} packet |
| 25907 | Restart the program being debugged. @var{XX}, while needed, is ignored. |
| 25908 | This packet is only available in extended mode (@pxref{extended mode}). |
| 25909 | |
| 25910 | The @samp{R} packet has no reply. |
| 25911 | |
| 25912 | @item s @r{[}@var{addr}@r{]} |
| 25913 | @cindex @samp{s} packet |
| 25914 | Single step. @var{addr} is the address at which to resume. If |
| 25915 | @var{addr} is omitted, resume at same address. |
| 25916 | |
| 25917 | Reply: |
| 25918 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25919 | |
| 25920 | @item S @var{sig}@r{[};@var{addr}@r{]} |
| 25921 | @anchor{step with signal packet} |
| 25922 | @cindex @samp{S} packet |
| 25923 | Step with signal. This is analogous to the @samp{C} packet, but |
| 25924 | requests a single-step, rather than a normal resumption of execution. |
| 25925 | |
| 25926 | Reply: |
| 25927 | @xref{Stop Reply Packets}, for the reply specifications. |
| 25928 | |
| 25929 | @item t @var{addr}:@var{PP},@var{MM} |
| 25930 | @cindex @samp{t} packet |
| 25931 | Search backwards starting at address @var{addr} for a match with pattern |
| 25932 | @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes. |
| 25933 | @var{addr} must be at least 3 digits. |
| 25934 | |
| 25935 | @item T @var{thread-id} |
| 25936 | @cindex @samp{T} packet |
| 25937 | Find out if the thread @var{thread-id} is alive. @xref{thread-id syntax}. |
| 25938 | |
| 25939 | Reply: |
| 25940 | @table @samp |
| 25941 | @item OK |
| 25942 | thread is still alive |
| 25943 | @item E @var{NN} |
| 25944 | thread is dead |
| 25945 | @end table |
| 25946 | |
| 25947 | @item v |
| 25948 | Packets starting with @samp{v} are identified by a multi-letter name, |
| 25949 | up to the first @samp{;} or @samp{?} (or the end of the packet). |
| 25950 | |
| 25951 | @item vAttach;@var{pid} |
| 25952 | @cindex @samp{vAttach} packet |
| 25953 | Attach to a new process with the specified process ID @var{pid}. |
| 25954 | The process ID is a |
| 25955 | hexadecimal integer identifying the process. In all-stop mode, all |
| 25956 | threads in the attached process are stopped; in non-stop mode, it may be |
| 25957 | attached without being stopped if that is supported by the target. |
| 25958 | |
| 25959 | @c In non-stop mode, on a successful vAttach, the stub should set the |
| 25960 | @c current thread to a thread of the newly-attached process. After |
| 25961 | @c attaching, GDB queries for the attached process's thread ID with qC. |
| 25962 | @c Also note that, from a user perspective, whether or not the |
| 25963 | @c target is stopped on attach in non-stop mode depends on whether you |
| 25964 | @c use the foreground or background version of the attach command, not |
| 25965 | @c on what vAttach does; GDB does the right thing with respect to either |
| 25966 | @c stopping or restarting threads. |
| 25967 | |
| 25968 | This packet is only available in extended mode (@pxref{extended mode}). |
| 25969 | |
| 25970 | Reply: |
| 25971 | @table @samp |
| 25972 | @item E @var{nn} |
| 25973 | for an error |
| 25974 | @item @r{Any stop packet} |
| 25975 | for success in all-stop mode (@pxref{Stop Reply Packets}) |
| 25976 | @item OK |
| 25977 | for success in non-stop mode (@pxref{Remote Non-Stop}) |
| 25978 | @end table |
| 25979 | |
| 25980 | @item vCont@r{[};@var{action}@r{[}:@var{thread-id}@r{]]}@dots{} |
| 25981 | @cindex @samp{vCont} packet |
| 25982 | Resume the inferior, specifying different actions for each thread. |
| 25983 | If an action is specified with no @var{thread-id}, then it is applied to any |
| 25984 | threads that don't have a specific action specified; if no default action is |
| 25985 | specified then other threads should remain stopped in all-stop mode and |
| 25986 | in their current state in non-stop mode. |
| 25987 | Specifying multiple |
| 25988 | default actions is an error; specifying no actions is also an error. |
| 25989 | Thread IDs are specified using the syntax described in @ref{thread-id syntax}. |
| 25990 | |
| 25991 | Currently supported actions are: |
| 25992 | |
| 25993 | @table @samp |
| 25994 | @item c |
| 25995 | Continue. |
| 25996 | @item C @var{sig} |
| 25997 | Continue with signal @var{sig}. The signal @var{sig} should be two hex digits. |
| 25998 | @item s |
| 25999 | Step. |
| 26000 | @item S @var{sig} |
| 26001 | Step with signal @var{sig}. The signal @var{sig} should be two hex digits. |
| 26002 | @item t |
| 26003 | Stop. |
| 26004 | @item T @var{sig} |
| 26005 | Stop with signal @var{sig}. The signal @var{sig} should be two hex digits. |
| 26006 | @end table |
| 26007 | |
| 26008 | The optional argument @var{addr} normally associated with the |
| 26009 | @samp{c}, @samp{C}, @samp{s}, and @samp{S} packets is |
| 26010 | not supported in @samp{vCont}. |
| 26011 | |
| 26012 | The @samp{t} and @samp{T} actions are only relevant in non-stop mode |
| 26013 | (@pxref{Remote Non-Stop}) and may be ignored by the stub otherwise. |
| 26014 | A stop reply should be generated for any affected thread not already stopped. |
| 26015 | When a thread is stopped by means of a @samp{t} action, |
| 26016 | the corresponding stop reply should indicate that the thread has stopped with |
| 26017 | signal @samp{0}, regardless of whether the target uses some other signal |
| 26018 | as an implementation detail. |
| 26019 | |
| 26020 | Reply: |
| 26021 | @xref{Stop Reply Packets}, for the reply specifications. |
| 26022 | |
| 26023 | @item vCont? |
| 26024 | @cindex @samp{vCont?} packet |
| 26025 | Request a list of actions supported by the @samp{vCont} packet. |
| 26026 | |
| 26027 | Reply: |
| 26028 | @table @samp |
| 26029 | @item vCont@r{[};@var{action}@dots{}@r{]} |
| 26030 | The @samp{vCont} packet is supported. Each @var{action} is a supported |
| 26031 | command in the @samp{vCont} packet. |
| 26032 | @item |
| 26033 | The @samp{vCont} packet is not supported. |
| 26034 | @end table |
| 26035 | |
| 26036 | @item vFile:@var{operation}:@var{parameter}@dots{} |
| 26037 | @cindex @samp{vFile} packet |
| 26038 | Perform a file operation on the target system. For details, |
| 26039 | see @ref{Host I/O Packets}. |
| 26040 | |
| 26041 | @item vFlashErase:@var{addr},@var{length} |
| 26042 | @cindex @samp{vFlashErase} packet |
| 26043 | Direct the stub to erase @var{length} bytes of flash starting at |
| 26044 | @var{addr}. The region may enclose any number of flash blocks, but |
| 26045 | its start and end must fall on block boundaries, as indicated by the |
| 26046 | flash block size appearing in the memory map (@pxref{Memory Map |
| 26047 | Format}). @value{GDBN} groups flash memory programming operations |
| 26048 | together, and sends a @samp{vFlashDone} request after each group; the |
| 26049 | stub is allowed to delay erase operation until the @samp{vFlashDone} |
| 26050 | packet is received. |
| 26051 | |
| 26052 | The stub must support @samp{vCont} if it reports support for |
| 26053 | multiprocess extensions (@pxref{multiprocess extensions}). Note that in |
| 26054 | this case @samp{vCont} actions can be specified to apply to all threads |
| 26055 | in a process by using the @samp{p@var{pid}.-1} form of the |
| 26056 | @var{thread-id}. |
| 26057 | |
| 26058 | Reply: |
| 26059 | @table @samp |
| 26060 | @item OK |
| 26061 | for success |
| 26062 | @item E @var{NN} |
| 26063 | for an error |
| 26064 | @end table |
| 26065 | |
| 26066 | @item vFlashWrite:@var{addr}:@var{XX@dots{}} |
| 26067 | @cindex @samp{vFlashWrite} packet |
| 26068 | Direct the stub to write data to flash address @var{addr}. The data |
| 26069 | is passed in binary form using the same encoding as for the @samp{X} |
| 26070 | packet (@pxref{Binary Data}). The memory ranges specified by |
| 26071 | @samp{vFlashWrite} packets preceding a @samp{vFlashDone} packet must |
| 26072 | not overlap, and must appear in order of increasing addresses |
| 26073 | (although @samp{vFlashErase} packets for higher addresses may already |
| 26074 | have been received; the ordering is guaranteed only between |
| 26075 | @samp{vFlashWrite} packets). If a packet writes to an address that was |
| 26076 | neither erased by a preceding @samp{vFlashErase} packet nor by some other |
| 26077 | target-specific method, the results are unpredictable. |
| 26078 | |
| 26079 | |
| 26080 | Reply: |
| 26081 | @table @samp |
| 26082 | @item OK |
| 26083 | for success |
| 26084 | @item E.memtype |
| 26085 | for vFlashWrite addressing non-flash memory |
| 26086 | @item E @var{NN} |
| 26087 | for an error |
| 26088 | @end table |
| 26089 | |
| 26090 | @item vFlashDone |
| 26091 | @cindex @samp{vFlashDone} packet |
| 26092 | Indicate to the stub that flash programming operation is finished. |
| 26093 | The stub is permitted to delay or batch the effects of a group of |
| 26094 | @samp{vFlashErase} and @samp{vFlashWrite} packets until a |
| 26095 | @samp{vFlashDone} packet is received. The contents of the affected |
| 26096 | regions of flash memory are unpredictable until the @samp{vFlashDone} |
| 26097 | request is completed. |
| 26098 | |
| 26099 | @item vKill;@var{pid} |
| 26100 | @cindex @samp{vKill} packet |
| 26101 | Kill the process with the specified process ID. @var{pid} is a |
| 26102 | hexadecimal integer identifying the process. This packet is used in |
| 26103 | preference to @samp{k} when multiprocess protocol extensions are |
| 26104 | supported; see @ref{multiprocess extensions}. |
| 26105 | |
| 26106 | Reply: |
| 26107 | @table @samp |
| 26108 | @item E @var{nn} |
| 26109 | for an error |
| 26110 | @item OK |
| 26111 | for success |
| 26112 | @end table |
| 26113 | |
| 26114 | @item vRun;@var{filename}@r{[};@var{argument}@r{]}@dots{} |
| 26115 | @cindex @samp{vRun} packet |
| 26116 | Run the program @var{filename}, passing it each @var{argument} on its |
| 26117 | command line. The file and arguments are hex-encoded strings. If |
| 26118 | @var{filename} is an empty string, the stub may use a default program |
| 26119 | (e.g.@: the last program run). The program is created in the stopped |
| 26120 | state. |
| 26121 | |
| 26122 | @c FIXME: What about non-stop mode? |
| 26123 | |
| 26124 | This packet is only available in extended mode (@pxref{extended mode}). |
| 26125 | |
| 26126 | Reply: |
| 26127 | @table @samp |
| 26128 | @item E @var{nn} |
| 26129 | for an error |
| 26130 | @item @r{Any stop packet} |
| 26131 | for success (@pxref{Stop Reply Packets}) |
| 26132 | @end table |
| 26133 | |
| 26134 | @item vStopped |
| 26135 | @anchor{vStopped packet} |
| 26136 | @cindex @samp{vStopped} packet |
| 26137 | |
| 26138 | In non-stop mode (@pxref{Remote Non-Stop}), acknowledge a previous stop |
| 26139 | reply and prompt for the stub to report another one. |
| 26140 | |
| 26141 | Reply: |
| 26142 | @table @samp |
| 26143 | @item @r{Any stop packet} |
| 26144 | if there is another unreported stop event (@pxref{Stop Reply Packets}) |
| 26145 | @item OK |
| 26146 | if there are no unreported stop events |
| 26147 | @end table |
| 26148 | |
| 26149 | @item X @var{addr},@var{length}:@var{XX@dots{}} |
| 26150 | @anchor{X packet} |
| 26151 | @cindex @samp{X} packet |
| 26152 | Write data to memory, where the data is transmitted in binary. |
| 26153 | @var{addr} is address, @var{length} is number of bytes, |
| 26154 | @samp{@var{XX}@dots{}} is binary data (@pxref{Binary Data}). |
| 26155 | |
| 26156 | Reply: |
| 26157 | @table @samp |
| 26158 | @item OK |
| 26159 | for success |
| 26160 | @item E @var{NN} |
| 26161 | for an error |
| 26162 | @end table |
| 26163 | |
| 26164 | @item z @var{type},@var{addr},@var{length} |
| 26165 | @itemx Z @var{type},@var{addr},@var{length} |
| 26166 | @anchor{insert breakpoint or watchpoint packet} |
| 26167 | @cindex @samp{z} packet |
| 26168 | @cindex @samp{Z} packets |
| 26169 | Insert (@samp{Z}) or remove (@samp{z}) a @var{type} breakpoint or |
| 26170 | watchpoint starting at address @var{address} and covering the next |
| 26171 | @var{length} bytes. |
| 26172 | |
| 26173 | Each breakpoint and watchpoint packet @var{type} is documented |
| 26174 | separately. |
| 26175 | |
| 26176 | @emph{Implementation notes: A remote target shall return an empty string |
| 26177 | for an unrecognized breakpoint or watchpoint packet @var{type}. A |
| 26178 | remote target shall support either both or neither of a given |
| 26179 | @samp{Z@var{type}@dots{}} and @samp{z@var{type}@dots{}} packet pair. To |
| 26180 | avoid potential problems with duplicate packets, the operations should |
| 26181 | be implemented in an idempotent way.} |
| 26182 | |
| 26183 | @item z0,@var{addr},@var{length} |
| 26184 | @itemx Z0,@var{addr},@var{length} |
| 26185 | @cindex @samp{z0} packet |
| 26186 | @cindex @samp{Z0} packet |
| 26187 | Insert (@samp{Z0}) or remove (@samp{z0}) a memory breakpoint at address |
| 26188 | @var{addr} of size @var{length}. |
| 26189 | |
| 26190 | A memory breakpoint is implemented by replacing the instruction at |
| 26191 | @var{addr} with a software breakpoint or trap instruction. The |
| 26192 | @var{length} is used by targets that indicates the size of the |
| 26193 | breakpoint (in bytes) that should be inserted (e.g., the @sc{arm} and |
| 26194 | @sc{mips} can insert either a 2 or 4 byte breakpoint). |
| 26195 | |
| 26196 | @emph{Implementation note: It is possible for a target to copy or move |
| 26197 | code that contains memory breakpoints (e.g., when implementing |
| 26198 | overlays). The behavior of this packet, in the presence of such a |
| 26199 | target, is not defined.} |
| 26200 | |
| 26201 | Reply: |
| 26202 | @table @samp |
| 26203 | @item OK |
| 26204 | success |
| 26205 | @item |
| 26206 | not supported |
| 26207 | @item E @var{NN} |
| 26208 | for an error |
| 26209 | @end table |
| 26210 | |
| 26211 | @item z1,@var{addr},@var{length} |
| 26212 | @itemx Z1,@var{addr},@var{length} |
| 26213 | @cindex @samp{z1} packet |
| 26214 | @cindex @samp{Z1} packet |
| 26215 | Insert (@samp{Z1}) or remove (@samp{z1}) a hardware breakpoint at |
| 26216 | address @var{addr} of size @var{length}. |
| 26217 | |
| 26218 | A hardware breakpoint is implemented using a mechanism that is not |
| 26219 | dependant on being able to modify the target's memory. |
| 26220 | |
| 26221 | @emph{Implementation note: A hardware breakpoint is not affected by code |
| 26222 | movement.} |
| 26223 | |
| 26224 | Reply: |
| 26225 | @table @samp |
| 26226 | @item OK |
| 26227 | success |
| 26228 | @item |
| 26229 | not supported |
| 26230 | @item E @var{NN} |
| 26231 | for an error |
| 26232 | @end table |
| 26233 | |
| 26234 | @item z2,@var{addr},@var{length} |
| 26235 | @itemx Z2,@var{addr},@var{length} |
| 26236 | @cindex @samp{z2} packet |
| 26237 | @cindex @samp{Z2} packet |
| 26238 | Insert (@samp{Z2}) or remove (@samp{z2}) a write watchpoint. |
| 26239 | |
| 26240 | Reply: |
| 26241 | @table @samp |
| 26242 | @item OK |
| 26243 | success |
| 26244 | @item |
| 26245 | not supported |
| 26246 | @item E @var{NN} |
| 26247 | for an error |
| 26248 | @end table |
| 26249 | |
| 26250 | @item z3,@var{addr},@var{length} |
| 26251 | @itemx Z3,@var{addr},@var{length} |
| 26252 | @cindex @samp{z3} packet |
| 26253 | @cindex @samp{Z3} packet |
| 26254 | Insert (@samp{Z3}) or remove (@samp{z3}) a read watchpoint. |
| 26255 | |
| 26256 | Reply: |
| 26257 | @table @samp |
| 26258 | @item OK |
| 26259 | success |
| 26260 | @item |
| 26261 | not supported |
| 26262 | @item E @var{NN} |
| 26263 | for an error |
| 26264 | @end table |
| 26265 | |
| 26266 | @item z4,@var{addr},@var{length} |
| 26267 | @itemx Z4,@var{addr},@var{length} |
| 26268 | @cindex @samp{z4} packet |
| 26269 | @cindex @samp{Z4} packet |
| 26270 | Insert (@samp{Z4}) or remove (@samp{z4}) an access watchpoint. |
| 26271 | |
| 26272 | Reply: |
| 26273 | @table @samp |
| 26274 | @item OK |
| 26275 | success |
| 26276 | @item |
| 26277 | not supported |
| 26278 | @item E @var{NN} |
| 26279 | for an error |
| 26280 | @end table |
| 26281 | |
| 26282 | @end table |
| 26283 | |
| 26284 | @node Stop Reply Packets |
| 26285 | @section Stop Reply Packets |
| 26286 | @cindex stop reply packets |
| 26287 | |
| 26288 | The @samp{C}, @samp{c}, @samp{S}, @samp{s}, @samp{vCont}, |
| 26289 | @samp{vAttach}, @samp{vRun}, @samp{vStopped}, and @samp{?} packets can |
| 26290 | receive any of the below as a reply. Except for @samp{?} |
| 26291 | and @samp{vStopped}, that reply is only returned |
| 26292 | when the target halts. In the below the exact meaning of @dfn{signal |
| 26293 | number} is defined by the header @file{include/gdb/signals.h} in the |
| 26294 | @value{GDBN} source code. |
| 26295 | |
| 26296 | As in the description of request packets, we include spaces in the |
| 26297 | reply templates for clarity; these are not part of the reply packet's |
| 26298 | syntax. No @value{GDBN} stop reply packet uses spaces to separate its |
| 26299 | components. |
| 26300 | |
| 26301 | @table @samp |
| 26302 | |
| 26303 | @item S @var{AA} |
| 26304 | The program received signal number @var{AA} (a two-digit hexadecimal |
| 26305 | number). This is equivalent to a @samp{T} response with no |
| 26306 | @var{n}:@var{r} pairs. |
| 26307 | |
| 26308 | @item T @var{AA} @var{n1}:@var{r1};@var{n2}:@var{r2};@dots{} |
| 26309 | @cindex @samp{T} packet reply |
| 26310 | The program received signal number @var{AA} (a two-digit hexadecimal |
| 26311 | number). This is equivalent to an @samp{S} response, except that the |
| 26312 | @samp{@var{n}:@var{r}} pairs can carry values of important registers |
| 26313 | and other information directly in the stop reply packet, reducing |
| 26314 | round-trip latency. Single-step and breakpoint traps are reported |
| 26315 | this way. Each @samp{@var{n}:@var{r}} pair is interpreted as follows: |
| 26316 | |
| 26317 | @itemize @bullet |
| 26318 | @item |
| 26319 | If @var{n} is a hexadecimal number, it is a register number, and the |
| 26320 | corresponding @var{r} gives that register's value. @var{r} is a |
| 26321 | series of bytes in target byte order, with each byte given by a |
| 26322 | two-digit hex number. |
| 26323 | |
| 26324 | @item |
| 26325 | If @var{n} is @samp{thread}, then @var{r} is the @var{thread-id} of |
| 26326 | the stopped thread, as specified in @ref{thread-id syntax}. |
| 26327 | |
| 26328 | @item |
| 26329 | If @var{n} is a recognized @dfn{stop reason}, it describes a more |
| 26330 | specific event that stopped the target. The currently defined stop |
| 26331 | reasons are listed below. @var{aa} should be @samp{05}, the trap |
| 26332 | signal. At most one stop reason should be present. |
| 26333 | |
| 26334 | @item |
| 26335 | Otherwise, @value{GDBN} should ignore this @samp{@var{n}:@var{r}} pair |
| 26336 | and go on to the next; this allows us to extend the protocol in the |
| 26337 | future. |
| 26338 | @end itemize |
| 26339 | |
| 26340 | The currently defined stop reasons are: |
| 26341 | |
| 26342 | @table @samp |
| 26343 | @item watch |
| 26344 | @itemx rwatch |
| 26345 | @itemx awatch |
| 26346 | The packet indicates a watchpoint hit, and @var{r} is the data address, in |
| 26347 | hex. |
| 26348 | |
| 26349 | @cindex shared library events, remote reply |
| 26350 | @item library |
| 26351 | The packet indicates that the loaded libraries have changed. |
| 26352 | @value{GDBN} should use @samp{qXfer:libraries:read} to fetch a new |
| 26353 | list of loaded libraries. @var{r} is ignored. |
| 26354 | |
| 26355 | @cindex replay log events, remote reply |
| 26356 | @item replaylog |
| 26357 | The packet indicates that the target cannot continue replaying |
| 26358 | logged execution events, because it has reached the end (or the |
| 26359 | beginning when executing backward) of the log. The value of @var{r} |
| 26360 | will be either @samp{begin} or @samp{end}. @xref{Reverse Execution}, |
| 26361 | for more information. |
| 26362 | |
| 26363 | |
| 26364 | @end table |
| 26365 | |
| 26366 | @item W @var{AA} |
| 26367 | @itemx W @var{AA} ; process:@var{pid} |
| 26368 | The process exited, and @var{AA} is the exit status. This is only |
| 26369 | applicable to certain targets. |
| 26370 | |
| 26371 | The second form of the response, including the process ID of the exited |
| 26372 | process, can be used only when @value{GDBN} has reported support for |
| 26373 | multiprocess protocol extensions; see @ref{multiprocess extensions}. |
| 26374 | The @var{pid} is formatted as a big-endian hex string. |
| 26375 | |
| 26376 | @item X @var{AA} |
| 26377 | @itemx X @var{AA} ; process:@var{pid} |
| 26378 | The process terminated with signal @var{AA}. |
| 26379 | |
| 26380 | The second form of the response, including the process ID of the |
| 26381 | terminated process, can be used only when @value{GDBN} has reported |
| 26382 | support for multiprocess protocol extensions; see @ref{multiprocess |
| 26383 | extensions}. The @var{pid} is formatted as a big-endian hex string. |
| 26384 | |
| 26385 | @item O @var{XX}@dots{} |
| 26386 | @samp{@var{XX}@dots{}} is hex encoding of @sc{ascii} data, to be |
| 26387 | written as the program's console output. This can happen at any time |
| 26388 | while the program is running and the debugger should continue to wait |
| 26389 | for @samp{W}, @samp{T}, etc. This reply is not permitted in non-stop mode. |
| 26390 | |
| 26391 | @item F @var{call-id},@var{parameter}@dots{} |
| 26392 | @var{call-id} is the identifier which says which host system call should |
| 26393 | be called. This is just the name of the function. Translation into the |
| 26394 | correct system call is only applicable as it's defined in @value{GDBN}. |
| 26395 | @xref{File-I/O Remote Protocol Extension}, for a list of implemented |
| 26396 | system calls. |
| 26397 | |
| 26398 | @samp{@var{parameter}@dots{}} is a list of parameters as defined for |
| 26399 | this very system call. |
| 26400 | |
| 26401 | The target replies with this packet when it expects @value{GDBN} to |
| 26402 | call a host system call on behalf of the target. @value{GDBN} replies |
| 26403 | with an appropriate @samp{F} packet and keeps up waiting for the next |
| 26404 | reply packet from the target. The latest @samp{C}, @samp{c}, @samp{S} |
| 26405 | or @samp{s} action is expected to be continued. @xref{File-I/O Remote |
| 26406 | Protocol Extension}, for more details. |
| 26407 | |
| 26408 | @end table |
| 26409 | |
| 26410 | @node General Query Packets |
| 26411 | @section General Query Packets |
| 26412 | @cindex remote query requests |
| 26413 | |
| 26414 | Packets starting with @samp{q} are @dfn{general query packets}; |
| 26415 | packets starting with @samp{Q} are @dfn{general set packets}. General |
| 26416 | query and set packets are a semi-unified form for retrieving and |
| 26417 | sending information to and from the stub. |
| 26418 | |
| 26419 | The initial letter of a query or set packet is followed by a name |
| 26420 | indicating what sort of thing the packet applies to. For example, |
| 26421 | @value{GDBN} may use a @samp{qSymbol} packet to exchange symbol |
| 26422 | definitions with the stub. These packet names follow some |
| 26423 | conventions: |
| 26424 | |
| 26425 | @itemize @bullet |
| 26426 | @item |
| 26427 | The name must not contain commas, colons or semicolons. |
| 26428 | @item |
| 26429 | Most @value{GDBN} query and set packets have a leading upper case |
| 26430 | letter. |
| 26431 | @item |
| 26432 | The names of custom vendor packets should use a company prefix, in |
| 26433 | lower case, followed by a period. For example, packets designed at |
| 26434 | the Acme Corporation might begin with @samp{qacme.foo} (for querying |
| 26435 | foos) or @samp{Qacme.bar} (for setting bars). |
| 26436 | @end itemize |
| 26437 | |
| 26438 | The name of a query or set packet should be separated from any |
| 26439 | parameters by a @samp{:}; the parameters themselves should be |
| 26440 | separated by @samp{,} or @samp{;}. Stubs must be careful to match the |
| 26441 | full packet name, and check for a separator or the end of the packet, |
| 26442 | in case two packet names share a common prefix. New packets should not begin |
| 26443 | with @samp{qC}, @samp{qP}, or @samp{qL}@footnote{The @samp{qP} and @samp{qL} |
| 26444 | packets predate these conventions, and have arguments without any terminator |
| 26445 | for the packet name; we suspect they are in widespread use in places that |
| 26446 | are difficult to upgrade. The @samp{qC} packet has no arguments, but some |
| 26447 | existing stubs (e.g.@: RedBoot) are known to not check for the end of the |
| 26448 | packet.}. |
| 26449 | |
| 26450 | Like the descriptions of the other packets, each description here |
| 26451 | has a template showing the packet's overall syntax, followed by an |
| 26452 | explanation of the packet's meaning. We include spaces in some of the |
| 26453 | templates for clarity; these are not part of the packet's syntax. No |
| 26454 | @value{GDBN} packet uses spaces to separate its components. |
| 26455 | |
| 26456 | Here are the currently defined query and set packets: |
| 26457 | |
| 26458 | @table @samp |
| 26459 | |
| 26460 | @item qC |
| 26461 | @cindex current thread, remote request |
| 26462 | @cindex @samp{qC} packet |
| 26463 | Return the current thread ID. |
| 26464 | |
| 26465 | Reply: |
| 26466 | @table @samp |
| 26467 | @item QC @var{thread-id} |
| 26468 | Where @var{thread-id} is a thread ID as documented in |
| 26469 | @ref{thread-id syntax}. |
| 26470 | @item @r{(anything else)} |
| 26471 | Any other reply implies the old thread ID. |
| 26472 | @end table |
| 26473 | |
| 26474 | @item qCRC:@var{addr},@var{length} |
| 26475 | @cindex CRC of memory block, remote request |
| 26476 | @cindex @samp{qCRC} packet |
| 26477 | Compute the CRC checksum of a block of memory. |
| 26478 | Reply: |
| 26479 | @table @samp |
| 26480 | @item E @var{NN} |
| 26481 | An error (such as memory fault) |
| 26482 | @item C @var{crc32} |
| 26483 | The specified memory region's checksum is @var{crc32}. |
| 26484 | @end table |
| 26485 | |
| 26486 | @item qfThreadInfo |
| 26487 | @itemx qsThreadInfo |
| 26488 | @cindex list active threads, remote request |
| 26489 | @cindex @samp{qfThreadInfo} packet |
| 26490 | @cindex @samp{qsThreadInfo} packet |
| 26491 | Obtain a list of all active thread IDs from the target (OS). Since there |
| 26492 | may be too many active threads to fit into one reply packet, this query |
| 26493 | works iteratively: it may require more than one query/reply sequence to |
| 26494 | obtain the entire list of threads. The first query of the sequence will |
| 26495 | be the @samp{qfThreadInfo} query; subsequent queries in the |
| 26496 | sequence will be the @samp{qsThreadInfo} query. |
| 26497 | |
| 26498 | NOTE: This packet replaces the @samp{qL} query (see below). |
| 26499 | |
| 26500 | Reply: |
| 26501 | @table @samp |
| 26502 | @item m @var{thread-id} |
| 26503 | A single thread ID |
| 26504 | @item m @var{thread-id},@var{thread-id}@dots{} |
| 26505 | a comma-separated list of thread IDs |
| 26506 | @item l |
| 26507 | (lower case letter @samp{L}) denotes end of list. |
| 26508 | @end table |
| 26509 | |
| 26510 | In response to each query, the target will reply with a list of one or |
| 26511 | more thread IDs, separated by commas. |
| 26512 | @value{GDBN} will respond to each reply with a request for more thread |
| 26513 | ids (using the @samp{qs} form of the query), until the target responds |
| 26514 | with @samp{l} (lower-case el, for @dfn{last}). |
| 26515 | Refer to @ref{thread-id syntax}, for the format of the @var{thread-id} |
| 26516 | fields. |
| 26517 | |
| 26518 | @item qGetTLSAddr:@var{thread-id},@var{offset},@var{lm} |
| 26519 | @cindex get thread-local storage address, remote request |
| 26520 | @cindex @samp{qGetTLSAddr} packet |
| 26521 | Fetch the address associated with thread local storage specified |
| 26522 | by @var{thread-id}, @var{offset}, and @var{lm}. |
| 26523 | |
| 26524 | @var{thread-id} is the thread ID associated with the |
| 26525 | thread for which to fetch the TLS address. @xref{thread-id syntax}. |
| 26526 | |
| 26527 | @var{offset} is the (big endian, hex encoded) offset associated with the |
| 26528 | thread local variable. (This offset is obtained from the debug |
| 26529 | information associated with the variable.) |
| 26530 | |
| 26531 | @var{lm} is the (big endian, hex encoded) OS/ABI-specific encoding of the |
| 26532 | the load module associated with the thread local storage. For example, |
| 26533 | a @sc{gnu}/Linux system will pass the link map address of the shared |
| 26534 | object associated with the thread local storage under consideration. |
| 26535 | Other operating environments may choose to represent the load module |
| 26536 | differently, so the precise meaning of this parameter will vary. |
| 26537 | |
| 26538 | Reply: |
| 26539 | @table @samp |
| 26540 | @item @var{XX}@dots{} |
| 26541 | Hex encoded (big endian) bytes representing the address of the thread |
| 26542 | local storage requested. |
| 26543 | |
| 26544 | @item E @var{nn} |
| 26545 | An error occurred. @var{nn} are hex digits. |
| 26546 | |
| 26547 | @item |
| 26548 | An empty reply indicates that @samp{qGetTLSAddr} is not supported by the stub. |
| 26549 | @end table |
| 26550 | |
| 26551 | @item qL @var{startflag} @var{threadcount} @var{nextthread} |
| 26552 | Obtain thread information from RTOS. Where: @var{startflag} (one hex |
| 26553 | digit) is one to indicate the first query and zero to indicate a |
| 26554 | subsequent query; @var{threadcount} (two hex digits) is the maximum |
| 26555 | number of threads the response packet can contain; and @var{nextthread} |
| 26556 | (eight hex digits), for subsequent queries (@var{startflag} is zero), is |
| 26557 | returned in the response as @var{argthread}. |
| 26558 | |
| 26559 | Don't use this packet; use the @samp{qfThreadInfo} query instead (see above). |
| 26560 | |
| 26561 | Reply: |
| 26562 | @table @samp |
| 26563 | @item qM @var{count} @var{done} @var{argthread} @var{thread}@dots{} |
| 26564 | Where: @var{count} (two hex digits) is the number of threads being |
| 26565 | returned; @var{done} (one hex digit) is zero to indicate more threads |
| 26566 | and one indicates no further threads; @var{argthreadid} (eight hex |
| 26567 | digits) is @var{nextthread} from the request packet; @var{thread}@dots{} |
| 26568 | is a sequence of thread IDs from the target. @var{threadid} (eight hex |
| 26569 | digits). See @code{remote.c:parse_threadlist_response()}. |
| 26570 | @end table |
| 26571 | |
| 26572 | @item qOffsets |
| 26573 | @cindex section offsets, remote request |
| 26574 | @cindex @samp{qOffsets} packet |
| 26575 | Get section offsets that the target used when relocating the downloaded |
| 26576 | image. |
| 26577 | |
| 26578 | Reply: |
| 26579 | @table @samp |
| 26580 | @item Text=@var{xxx};Data=@var{yyy}@r{[};Bss=@var{zzz}@r{]} |
| 26581 | Relocate the @code{Text} section by @var{xxx} from its original address. |
| 26582 | Relocate the @code{Data} section by @var{yyy} from its original address. |
| 26583 | If the object file format provides segment information (e.g.@: @sc{elf} |
| 26584 | @samp{PT_LOAD} program headers), @value{GDBN} will relocate entire |
| 26585 | segments by the supplied offsets. |
| 26586 | |
| 26587 | @emph{Note: while a @code{Bss} offset may be included in the response, |
| 26588 | @value{GDBN} ignores this and instead applies the @code{Data} offset |
| 26589 | to the @code{Bss} section.} |
| 26590 | |
| 26591 | @item TextSeg=@var{xxx}@r{[};DataSeg=@var{yyy}@r{]} |
| 26592 | Relocate the first segment of the object file, which conventionally |
| 26593 | contains program code, to a starting address of @var{xxx}. If |
| 26594 | @samp{DataSeg} is specified, relocate the second segment, which |
| 26595 | conventionally contains modifiable data, to a starting address of |
| 26596 | @var{yyy}. @value{GDBN} will report an error if the object file |
| 26597 | does not contain segment information, or does not contain at least |
| 26598 | as many segments as mentioned in the reply. Extra segments are |
| 26599 | kept at fixed offsets relative to the last relocated segment. |
| 26600 | @end table |
| 26601 | |
| 26602 | @item qP @var{mode} @var{thread-id} |
| 26603 | @cindex thread information, remote request |
| 26604 | @cindex @samp{qP} packet |
| 26605 | Returns information on @var{thread-id}. Where: @var{mode} is a hex |
| 26606 | encoded 32 bit mode; @var{thread-id} is a thread ID |
| 26607 | (@pxref{thread-id syntax}). |
| 26608 | |
| 26609 | Don't use this packet; use the @samp{qThreadExtraInfo} query instead |
| 26610 | (see below). |
| 26611 | |
| 26612 | Reply: see @code{remote.c:remote_unpack_thread_info_response()}. |
| 26613 | |
| 26614 | @item QNonStop:1 |
| 26615 | @item QNonStop:0 |
| 26616 | @cindex non-stop mode, remote request |
| 26617 | @cindex @samp{QNonStop} packet |
| 26618 | @anchor{QNonStop} |
| 26619 | Enter non-stop (@samp{QNonStop:1}) or all-stop (@samp{QNonStop:0}) mode. |
| 26620 | @xref{Remote Non-Stop}, for more information. |
| 26621 | |
| 26622 | Reply: |
| 26623 | @table @samp |
| 26624 | @item OK |
| 26625 | The request succeeded. |
| 26626 | |
| 26627 | @item E @var{nn} |
| 26628 | An error occurred. @var{nn} are hex digits. |
| 26629 | |
| 26630 | @item |
| 26631 | An empty reply indicates that @samp{QNonStop} is not supported by |
| 26632 | the stub. |
| 26633 | @end table |
| 26634 | |
| 26635 | This packet is not probed by default; the remote stub must request it, |
| 26636 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 26637 | Use of this packet is controlled by the @code{set non-stop} command; |
| 26638 | @pxref{Non-Stop Mode}. |
| 26639 | |
| 26640 | @item QPassSignals: @var{signal} @r{[};@var{signal}@r{]}@dots{} |
| 26641 | @cindex pass signals to inferior, remote request |
| 26642 | @cindex @samp{QPassSignals} packet |
| 26643 | @anchor{QPassSignals} |
| 26644 | Each listed @var{signal} should be passed directly to the inferior process. |
| 26645 | Signals are numbered identically to continue packets and stop replies |
| 26646 | (@pxref{Stop Reply Packets}). Each @var{signal} list item should be |
| 26647 | strictly greater than the previous item. These signals do not need to stop |
| 26648 | the inferior, or be reported to @value{GDBN}. All other signals should be |
| 26649 | reported to @value{GDBN}. Multiple @samp{QPassSignals} packets do not |
| 26650 | combine; any earlier @samp{QPassSignals} list is completely replaced by the |
| 26651 | new list. This packet improves performance when using @samp{handle |
| 26652 | @var{signal} nostop noprint pass}. |
| 26653 | |
| 26654 | Reply: |
| 26655 | @table @samp |
| 26656 | @item OK |
| 26657 | The request succeeded. |
| 26658 | |
| 26659 | @item E @var{nn} |
| 26660 | An error occurred. @var{nn} are hex digits. |
| 26661 | |
| 26662 | @item |
| 26663 | An empty reply indicates that @samp{QPassSignals} is not supported by |
| 26664 | the stub. |
| 26665 | @end table |
| 26666 | |
| 26667 | Use of this packet is controlled by the @code{set remote pass-signals} |
| 26668 | command (@pxref{Remote Configuration, set remote pass-signals}). |
| 26669 | This packet is not probed by default; the remote stub must request it, |
| 26670 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 26671 | |
| 26672 | @item qRcmd,@var{command} |
| 26673 | @cindex execute remote command, remote request |
| 26674 | @cindex @samp{qRcmd} packet |
| 26675 | @var{command} (hex encoded) is passed to the local interpreter for |
| 26676 | execution. Invalid commands should be reported using the output |
| 26677 | string. Before the final result packet, the target may also respond |
| 26678 | with a number of intermediate @samp{O@var{output}} console output |
| 26679 | packets. @emph{Implementors should note that providing access to a |
| 26680 | stubs's interpreter may have security implications}. |
| 26681 | |
| 26682 | Reply: |
| 26683 | @table @samp |
| 26684 | @item OK |
| 26685 | A command response with no output. |
| 26686 | @item @var{OUTPUT} |
| 26687 | A command response with the hex encoded output string @var{OUTPUT}. |
| 26688 | @item E @var{NN} |
| 26689 | Indicate a badly formed request. |
| 26690 | @item |
| 26691 | An empty reply indicates that @samp{qRcmd} is not recognized. |
| 26692 | @end table |
| 26693 | |
| 26694 | (Note that the @code{qRcmd} packet's name is separated from the |
| 26695 | command by a @samp{,}, not a @samp{:}, contrary to the naming |
| 26696 | conventions above. Please don't use this packet as a model for new |
| 26697 | packets.) |
| 26698 | |
| 26699 | @item qSearch:memory:@var{address};@var{length};@var{search-pattern} |
| 26700 | @cindex searching memory, in remote debugging |
| 26701 | @cindex @samp{qSearch:memory} packet |
| 26702 | @anchor{qSearch memory} |
| 26703 | Search @var{length} bytes at @var{address} for @var{search-pattern}. |
| 26704 | @var{address} and @var{length} are encoded in hex. |
| 26705 | @var{search-pattern} is a sequence of bytes, hex encoded. |
| 26706 | |
| 26707 | Reply: |
| 26708 | @table @samp |
| 26709 | @item 0 |
| 26710 | The pattern was not found. |
| 26711 | @item 1,address |
| 26712 | The pattern was found at @var{address}. |
| 26713 | @item E @var{NN} |
| 26714 | A badly formed request or an error was encountered while searching memory. |
| 26715 | @item |
| 26716 | An empty reply indicates that @samp{qSearch:memory} is not recognized. |
| 26717 | @end table |
| 26718 | |
| 26719 | @item QStartNoAckMode |
| 26720 | @cindex @samp{QStartNoAckMode} packet |
| 26721 | @anchor{QStartNoAckMode} |
| 26722 | Request that the remote stub disable the normal @samp{+}/@samp{-} |
| 26723 | protocol acknowledgments (@pxref{Packet Acknowledgment}). |
| 26724 | |
| 26725 | Reply: |
| 26726 | @table @samp |
| 26727 | @item OK |
| 26728 | The stub has switched to no-acknowledgment mode. |
| 26729 | @value{GDBN} acknowledges this reponse, |
| 26730 | but neither the stub nor @value{GDBN} shall send or expect further |
| 26731 | @samp{+}/@samp{-} acknowledgments in the current connection. |
| 26732 | @item |
| 26733 | An empty reply indicates that the stub does not support no-acknowledgment mode. |
| 26734 | @end table |
| 26735 | |
| 26736 | @item qSupported @r{[}:@var{gdbfeature} @r{[};@var{gdbfeature}@r{]}@dots{} @r{]} |
| 26737 | @cindex supported packets, remote query |
| 26738 | @cindex features of the remote protocol |
| 26739 | @cindex @samp{qSupported} packet |
| 26740 | @anchor{qSupported} |
| 26741 | Tell the remote stub about features supported by @value{GDBN}, and |
| 26742 | query the stub for features it supports. This packet allows |
| 26743 | @value{GDBN} and the remote stub to take advantage of each others' |
| 26744 | features. @samp{qSupported} also consolidates multiple feature probes |
| 26745 | at startup, to improve @value{GDBN} performance---a single larger |
| 26746 | packet performs better than multiple smaller probe packets on |
| 26747 | high-latency links. Some features may enable behavior which must not |
| 26748 | be on by default, e.g.@: because it would confuse older clients or |
| 26749 | stubs. Other features may describe packets which could be |
| 26750 | automatically probed for, but are not. These features must be |
| 26751 | reported before @value{GDBN} will use them. This ``default |
| 26752 | unsupported'' behavior is not appropriate for all packets, but it |
| 26753 | helps to keep the initial connection time under control with new |
| 26754 | versions of @value{GDBN} which support increasing numbers of packets. |
| 26755 | |
| 26756 | Reply: |
| 26757 | @table @samp |
| 26758 | @item @var{stubfeature} @r{[};@var{stubfeature}@r{]}@dots{} |
| 26759 | The stub supports or does not support each returned @var{stubfeature}, |
| 26760 | depending on the form of each @var{stubfeature} (see below for the |
| 26761 | possible forms). |
| 26762 | @item |
| 26763 | An empty reply indicates that @samp{qSupported} is not recognized, |
| 26764 | or that no features needed to be reported to @value{GDBN}. |
| 26765 | @end table |
| 26766 | |
| 26767 | The allowed forms for each feature (either a @var{gdbfeature} in the |
| 26768 | @samp{qSupported} packet, or a @var{stubfeature} in the response) |
| 26769 | are: |
| 26770 | |
| 26771 | @table @samp |
| 26772 | @item @var{name}=@var{value} |
| 26773 | The remote protocol feature @var{name} is supported, and associated |
| 26774 | with the specified @var{value}. The format of @var{value} depends |
| 26775 | on the feature, but it must not include a semicolon. |
| 26776 | @item @var{name}+ |
| 26777 | The remote protocol feature @var{name} is supported, and does not |
| 26778 | need an associated value. |
| 26779 | @item @var{name}- |
| 26780 | The remote protocol feature @var{name} is not supported. |
| 26781 | @item @var{name}? |
| 26782 | The remote protocol feature @var{name} may be supported, and |
| 26783 | @value{GDBN} should auto-detect support in some other way when it is |
| 26784 | needed. This form will not be used for @var{gdbfeature} notifications, |
| 26785 | but may be used for @var{stubfeature} responses. |
| 26786 | @end table |
| 26787 | |
| 26788 | Whenever the stub receives a @samp{qSupported} request, the |
| 26789 | supplied set of @value{GDBN} features should override any previous |
| 26790 | request. This allows @value{GDBN} to put the stub in a known |
| 26791 | state, even if the stub had previously been communicating with |
| 26792 | a different version of @value{GDBN}. |
| 26793 | |
| 26794 | The following values of @var{gdbfeature} (for the packet sent by @value{GDBN}) |
| 26795 | are defined: |
| 26796 | |
| 26797 | @table @samp |
| 26798 | @item multiprocess |
| 26799 | This feature indicates whether @value{GDBN} supports multiprocess |
| 26800 | extensions to the remote protocol. @value{GDBN} does not use such |
| 26801 | extensions unless the stub also reports that it supports them by |
| 26802 | including @samp{multiprocess+} in its @samp{qSupported} reply. |
| 26803 | @xref{multiprocess extensions}, for details. |
| 26804 | @end table |
| 26805 | |
| 26806 | Stubs should ignore any unknown values for |
| 26807 | @var{gdbfeature}. Any @value{GDBN} which sends a @samp{qSupported} |
| 26808 | packet supports receiving packets of unlimited length (earlier |
| 26809 | versions of @value{GDBN} may reject overly long responses). Additional values |
| 26810 | for @var{gdbfeature} may be defined in the future to let the stub take |
| 26811 | advantage of new features in @value{GDBN}, e.g.@: incompatible |
| 26812 | improvements in the remote protocol---the @samp{multiprocess} feature is |
| 26813 | an example of such a feature. The stub's reply should be independent |
| 26814 | of the @var{gdbfeature} entries sent by @value{GDBN}; first @value{GDBN} |
| 26815 | describes all the features it supports, and then the stub replies with |
| 26816 | all the features it supports. |
| 26817 | |
| 26818 | Similarly, @value{GDBN} will silently ignore unrecognized stub feature |
| 26819 | responses, as long as each response uses one of the standard forms. |
| 26820 | |
| 26821 | Some features are flags. A stub which supports a flag feature |
| 26822 | should respond with a @samp{+} form response. Other features |
| 26823 | require values, and the stub should respond with an @samp{=} |
| 26824 | form response. |
| 26825 | |
| 26826 | Each feature has a default value, which @value{GDBN} will use if |
| 26827 | @samp{qSupported} is not available or if the feature is not mentioned |
| 26828 | in the @samp{qSupported} response. The default values are fixed; a |
| 26829 | stub is free to omit any feature responses that match the defaults. |
| 26830 | |
| 26831 | Not all features can be probed, but for those which can, the probing |
| 26832 | mechanism is useful: in some cases, a stub's internal |
| 26833 | architecture may not allow the protocol layer to know some information |
| 26834 | about the underlying target in advance. This is especially common in |
| 26835 | stubs which may be configured for multiple targets. |
| 26836 | |
| 26837 | These are the currently defined stub features and their properties: |
| 26838 | |
| 26839 | @multitable @columnfractions 0.35 0.2 0.12 0.2 |
| 26840 | @c NOTE: The first row should be @headitem, but we do not yet require |
| 26841 | @c a new enough version of Texinfo (4.7) to use @headitem. |
| 26842 | @item Feature Name |
| 26843 | @tab Value Required |
| 26844 | @tab Default |
| 26845 | @tab Probe Allowed |
| 26846 | |
| 26847 | @item @samp{PacketSize} |
| 26848 | @tab Yes |
| 26849 | @tab @samp{-} |
| 26850 | @tab No |
| 26851 | |
| 26852 | @item @samp{qXfer:auxv:read} |
| 26853 | @tab No |
| 26854 | @tab @samp{-} |
| 26855 | @tab Yes |
| 26856 | |
| 26857 | @item @samp{qXfer:features:read} |
| 26858 | @tab No |
| 26859 | @tab @samp{-} |
| 26860 | @tab Yes |
| 26861 | |
| 26862 | @item @samp{qXfer:libraries:read} |
| 26863 | @tab No |
| 26864 | @tab @samp{-} |
| 26865 | @tab Yes |
| 26866 | |
| 26867 | @item @samp{qXfer:memory-map:read} |
| 26868 | @tab No |
| 26869 | @tab @samp{-} |
| 26870 | @tab Yes |
| 26871 | |
| 26872 | @item @samp{qXfer:spu:read} |
| 26873 | @tab No |
| 26874 | @tab @samp{-} |
| 26875 | @tab Yes |
| 26876 | |
| 26877 | @item @samp{qXfer:spu:write} |
| 26878 | @tab No |
| 26879 | @tab @samp{-} |
| 26880 | @tab Yes |
| 26881 | |
| 26882 | @item @samp{QNonStop} |
| 26883 | @tab No |
| 26884 | @tab @samp{-} |
| 26885 | @tab Yes |
| 26886 | |
| 26887 | @item @samp{QPassSignals} |
| 26888 | @tab No |
| 26889 | @tab @samp{-} |
| 26890 | @tab Yes |
| 26891 | |
| 26892 | @item @samp{QStartNoAckMode} |
| 26893 | @tab No |
| 26894 | @tab @samp{-} |
| 26895 | @tab Yes |
| 26896 | |
| 26897 | @item @samp{multiprocess} |
| 26898 | @tab No |
| 26899 | @tab @samp{-} |
| 26900 | @tab No |
| 26901 | |
| 26902 | @end multitable |
| 26903 | |
| 26904 | These are the currently defined stub features, in more detail: |
| 26905 | |
| 26906 | @table @samp |
| 26907 | @cindex packet size, remote protocol |
| 26908 | @item PacketSize=@var{bytes} |
| 26909 | The remote stub can accept packets up to at least @var{bytes} in |
| 26910 | length. @value{GDBN} will send packets up to this size for bulk |
| 26911 | transfers, and will never send larger packets. This is a limit on the |
| 26912 | data characters in the packet, including the frame and checksum. |
| 26913 | There is no trailing NUL byte in a remote protocol packet; if the stub |
| 26914 | stores packets in a NUL-terminated format, it should allow an extra |
| 26915 | byte in its buffer for the NUL. If this stub feature is not supported, |
| 26916 | @value{GDBN} guesses based on the size of the @samp{g} packet response. |
| 26917 | |
| 26918 | @item qXfer:auxv:read |
| 26919 | The remote stub understands the @samp{qXfer:auxv:read} packet |
| 26920 | (@pxref{qXfer auxiliary vector read}). |
| 26921 | |
| 26922 | @item qXfer:features:read |
| 26923 | The remote stub understands the @samp{qXfer:features:read} packet |
| 26924 | (@pxref{qXfer target description read}). |
| 26925 | |
| 26926 | @item qXfer:libraries:read |
| 26927 | The remote stub understands the @samp{qXfer:libraries:read} packet |
| 26928 | (@pxref{qXfer library list read}). |
| 26929 | |
| 26930 | @item qXfer:memory-map:read |
| 26931 | The remote stub understands the @samp{qXfer:memory-map:read} packet |
| 26932 | (@pxref{qXfer memory map read}). |
| 26933 | |
| 26934 | @item qXfer:spu:read |
| 26935 | The remote stub understands the @samp{qXfer:spu:read} packet |
| 26936 | (@pxref{qXfer spu read}). |
| 26937 | |
| 26938 | @item qXfer:spu:write |
| 26939 | The remote stub understands the @samp{qXfer:spu:write} packet |
| 26940 | (@pxref{qXfer spu write}). |
| 26941 | |
| 26942 | @item QNonStop |
| 26943 | The remote stub understands the @samp{QNonStop} packet |
| 26944 | (@pxref{QNonStop}). |
| 26945 | |
| 26946 | @item QPassSignals |
| 26947 | The remote stub understands the @samp{QPassSignals} packet |
| 26948 | (@pxref{QPassSignals}). |
| 26949 | |
| 26950 | @item QStartNoAckMode |
| 26951 | The remote stub understands the @samp{QStartNoAckMode} packet and |
| 26952 | prefers to operate in no-acknowledgment mode. @xref{Packet Acknowledgment}. |
| 26953 | |
| 26954 | @item multiprocess |
| 26955 | @anchor{multiprocess extensions} |
| 26956 | @cindex multiprocess extensions, in remote protocol |
| 26957 | The remote stub understands the multiprocess extensions to the remote |
| 26958 | protocol syntax. The multiprocess extensions affect the syntax of |
| 26959 | thread IDs in both packets and replies (@pxref{thread-id syntax}), and |
| 26960 | add process IDs to the @samp{D} packet and @samp{W} and @samp{X} |
| 26961 | replies. Note that reporting this feature indicates support for the |
| 26962 | syntactic extensions only, not that the stub necessarily supports |
| 26963 | debugging of more than one process at a time. The stub must not use |
| 26964 | multiprocess extensions in packet replies unless @value{GDBN} has also |
| 26965 | indicated it supports them in its @samp{qSupported} request. |
| 26966 | |
| 26967 | @item qXfer:osdata:read |
| 26968 | The remote stub understands the @samp{qXfer:osdata:read} packet |
| 26969 | ((@pxref{qXfer osdata read}). |
| 26970 | |
| 26971 | @end table |
| 26972 | |
| 26973 | @item qSymbol:: |
| 26974 | @cindex symbol lookup, remote request |
| 26975 | @cindex @samp{qSymbol} packet |
| 26976 | Notify the target that @value{GDBN} is prepared to serve symbol lookup |
| 26977 | requests. Accept requests from the target for the values of symbols. |
| 26978 | |
| 26979 | Reply: |
| 26980 | @table @samp |
| 26981 | @item OK |
| 26982 | The target does not need to look up any (more) symbols. |
| 26983 | @item qSymbol:@var{sym_name} |
| 26984 | The target requests the value of symbol @var{sym_name} (hex encoded). |
| 26985 | @value{GDBN} may provide the value by using the |
| 26986 | @samp{qSymbol:@var{sym_value}:@var{sym_name}} message, described |
| 26987 | below. |
| 26988 | @end table |
| 26989 | |
| 26990 | @item qSymbol:@var{sym_value}:@var{sym_name} |
| 26991 | Set the value of @var{sym_name} to @var{sym_value}. |
| 26992 | |
| 26993 | @var{sym_name} (hex encoded) is the name of a symbol whose value the |
| 26994 | target has previously requested. |
| 26995 | |
| 26996 | @var{sym_value} (hex) is the value for symbol @var{sym_name}. If |
| 26997 | @value{GDBN} cannot supply a value for @var{sym_name}, then this field |
| 26998 | will be empty. |
| 26999 | |
| 27000 | Reply: |
| 27001 | @table @samp |
| 27002 | @item OK |
| 27003 | The target does not need to look up any (more) symbols. |
| 27004 | @item qSymbol:@var{sym_name} |
| 27005 | The target requests the value of a new symbol @var{sym_name} (hex |
| 27006 | encoded). @value{GDBN} will continue to supply the values of symbols |
| 27007 | (if available), until the target ceases to request them. |
| 27008 | @end table |
| 27009 | |
| 27010 | @item QTDP |
| 27011 | @itemx QTFrame |
| 27012 | @xref{Tracepoint Packets}. |
| 27013 | |
| 27014 | @item qThreadExtraInfo,@var{thread-id} |
| 27015 | @cindex thread attributes info, remote request |
| 27016 | @cindex @samp{qThreadExtraInfo} packet |
| 27017 | Obtain a printable string description of a thread's attributes from |
| 27018 | the target OS. @var{thread-id} is a thread ID; |
| 27019 | see @ref{thread-id syntax}. This |
| 27020 | string may contain anything that the target OS thinks is interesting |
| 27021 | for @value{GDBN} to tell the user about the thread. The string is |
| 27022 | displayed in @value{GDBN}'s @code{info threads} display. Some |
| 27023 | examples of possible thread extra info strings are @samp{Runnable}, or |
| 27024 | @samp{Blocked on Mutex}. |
| 27025 | |
| 27026 | Reply: |
| 27027 | @table @samp |
| 27028 | @item @var{XX}@dots{} |
| 27029 | Where @samp{@var{XX}@dots{}} is a hex encoding of @sc{ascii} data, |
| 27030 | comprising the printable string containing the extra information about |
| 27031 | the thread's attributes. |
| 27032 | @end table |
| 27033 | |
| 27034 | (Note that the @code{qThreadExtraInfo} packet's name is separated from |
| 27035 | the command by a @samp{,}, not a @samp{:}, contrary to the naming |
| 27036 | conventions above. Please don't use this packet as a model for new |
| 27037 | packets.) |
| 27038 | |
| 27039 | @item QTStart |
| 27040 | @itemx QTStop |
| 27041 | @itemx QTinit |
| 27042 | @itemx QTro |
| 27043 | @itemx qTStatus |
| 27044 | @xref{Tracepoint Packets}. |
| 27045 | |
| 27046 | @item qXfer:@var{object}:read:@var{annex}:@var{offset},@var{length} |
| 27047 | @cindex read special object, remote request |
| 27048 | @cindex @samp{qXfer} packet |
| 27049 | @anchor{qXfer read} |
| 27050 | Read uninterpreted bytes from the target's special data area |
| 27051 | identified by the keyword @var{object}. Request @var{length} bytes |
| 27052 | starting at @var{offset} bytes into the data. The content and |
| 27053 | encoding of @var{annex} is specific to @var{object}; it can supply |
| 27054 | additional details about what data to access. |
| 27055 | |
| 27056 | Here are the specific requests of this form defined so far. All |
| 27057 | @samp{qXfer:@var{object}:read:@dots{}} requests use the same reply |
| 27058 | formats, listed below. |
| 27059 | |
| 27060 | @table @samp |
| 27061 | @item qXfer:auxv:read::@var{offset},@var{length} |
| 27062 | @anchor{qXfer auxiliary vector read} |
| 27063 | Access the target's @dfn{auxiliary vector}. @xref{OS Information, |
| 27064 | auxiliary vector}. Note @var{annex} must be empty. |
| 27065 | |
| 27066 | This packet is not probed by default; the remote stub must request it, |
| 27067 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 27068 | |
| 27069 | @item qXfer:features:read:@var{annex}:@var{offset},@var{length} |
| 27070 | @anchor{qXfer target description read} |
| 27071 | Access the @dfn{target description}. @xref{Target Descriptions}. The |
| 27072 | annex specifies which XML document to access. The main description is |
| 27073 | always loaded from the @samp{target.xml} annex. |
| 27074 | |
| 27075 | This packet is not probed by default; the remote stub must request it, |
| 27076 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 27077 | |
| 27078 | @item qXfer:libraries:read:@var{annex}:@var{offset},@var{length} |
| 27079 | @anchor{qXfer library list read} |
| 27080 | Access the target's list of loaded libraries. @xref{Library List Format}. |
| 27081 | The annex part of the generic @samp{qXfer} packet must be empty |
| 27082 | (@pxref{qXfer read}). |
| 27083 | |
| 27084 | Targets which maintain a list of libraries in the program's memory do |
| 27085 | not need to implement this packet; it is designed for platforms where |
| 27086 | the operating system manages the list of loaded libraries. |
| 27087 | |
| 27088 | This packet is not probed by default; the remote stub must request it, |
| 27089 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 27090 | |
| 27091 | @item qXfer:memory-map:read::@var{offset},@var{length} |
| 27092 | @anchor{qXfer memory map read} |
| 27093 | Access the target's @dfn{memory-map}. @xref{Memory Map Format}. The |
| 27094 | annex part of the generic @samp{qXfer} packet must be empty |
| 27095 | (@pxref{qXfer read}). |
| 27096 | |
| 27097 | This packet is not probed by default; the remote stub must request it, |
| 27098 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 27099 | |
| 27100 | @item qXfer:spu:read:@var{annex}:@var{offset},@var{length} |
| 27101 | @anchor{qXfer spu read} |
| 27102 | Read contents of an @code{spufs} file on the target system. The |
| 27103 | annex specifies which file to read; it must be of the form |
| 27104 | @file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID |
| 27105 | in the target process, and @var{name} identifes the @code{spufs} file |
| 27106 | in that context to be accessed. |
| 27107 | |
| 27108 | This packet is not probed by default; the remote stub must request it, |
| 27109 | by supplying an appropriate @samp{qSupported} response |
| 27110 | (@pxref{qSupported}). |
| 27111 | |
| 27112 | @item qXfer:osdata:read::@var{offset},@var{length} |
| 27113 | @anchor{qXfer osdata read} |
| 27114 | Access the target's @dfn{operating system information}. |
| 27115 | @xref{Operating System Information}. |
| 27116 | |
| 27117 | @end table |
| 27118 | |
| 27119 | Reply: |
| 27120 | @table @samp |
| 27121 | @item m @var{data} |
| 27122 | Data @var{data} (@pxref{Binary Data}) has been read from the |
| 27123 | target. There may be more data at a higher address (although |
| 27124 | it is permitted to return @samp{m} even for the last valid |
| 27125 | block of data, as long as at least one byte of data was read). |
| 27126 | @var{data} may have fewer bytes than the @var{length} in the |
| 27127 | request. |
| 27128 | |
| 27129 | @item l @var{data} |
| 27130 | Data @var{data} (@pxref{Binary Data}) has been read from the target. |
| 27131 | There is no more data to be read. @var{data} may have fewer bytes |
| 27132 | than the @var{length} in the request. |
| 27133 | |
| 27134 | @item l |
| 27135 | The @var{offset} in the request is at the end of the data. |
| 27136 | There is no more data to be read. |
| 27137 | |
| 27138 | @item E00 |
| 27139 | The request was malformed, or @var{annex} was invalid. |
| 27140 | |
| 27141 | @item E @var{nn} |
| 27142 | The offset was invalid, or there was an error encountered reading the data. |
| 27143 | @var{nn} is a hex-encoded @code{errno} value. |
| 27144 | |
| 27145 | @item |
| 27146 | An empty reply indicates the @var{object} string was not recognized by |
| 27147 | the stub, or that the object does not support reading. |
| 27148 | @end table |
| 27149 | |
| 27150 | @item qXfer:@var{object}:write:@var{annex}:@var{offset}:@var{data}@dots{} |
| 27151 | @cindex write data into object, remote request |
| 27152 | Write uninterpreted bytes into the target's special data area |
| 27153 | identified by the keyword @var{object}, starting at @var{offset} bytes |
| 27154 | into the data. @var{data}@dots{} is the binary-encoded data |
| 27155 | (@pxref{Binary Data}) to be written. The content and encoding of @var{annex} |
| 27156 | is specific to @var{object}; it can supply additional details about what data |
| 27157 | to access. |
| 27158 | |
| 27159 | Here are the specific requests of this form defined so far. All |
| 27160 | @samp{qXfer:@var{object}:write:@dots{}} requests use the same reply |
| 27161 | formats, listed below. |
| 27162 | |
| 27163 | @table @samp |
| 27164 | @item qXfer:spu:write:@var{annex}:@var{offset}:@var{data}@dots{} |
| 27165 | @anchor{qXfer spu write} |
| 27166 | Write @var{data} to an @code{spufs} file on the target system. The |
| 27167 | annex specifies which file to write; it must be of the form |
| 27168 | @file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID |
| 27169 | in the target process, and @var{name} identifes the @code{spufs} file |
| 27170 | in that context to be accessed. |
| 27171 | |
| 27172 | This packet is not probed by default; the remote stub must request it, |
| 27173 | by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}). |
| 27174 | @end table |
| 27175 | |
| 27176 | Reply: |
| 27177 | @table @samp |
| 27178 | @item @var{nn} |
| 27179 | @var{nn} (hex encoded) is the number of bytes written. |
| 27180 | This may be fewer bytes than supplied in the request. |
| 27181 | |
| 27182 | @item E00 |
| 27183 | The request was malformed, or @var{annex} was invalid. |
| 27184 | |
| 27185 | @item E @var{nn} |
| 27186 | The offset was invalid, or there was an error encountered writing the data. |
| 27187 | @var{nn} is a hex-encoded @code{errno} value. |
| 27188 | |
| 27189 | @item |
| 27190 | An empty reply indicates the @var{object} string was not |
| 27191 | recognized by the stub, or that the object does not support writing. |
| 27192 | @end table |
| 27193 | |
| 27194 | @item qXfer:@var{object}:@var{operation}:@dots{} |
| 27195 | Requests of this form may be added in the future. When a stub does |
| 27196 | not recognize the @var{object} keyword, or its support for |
| 27197 | @var{object} does not recognize the @var{operation} keyword, the stub |
| 27198 | must respond with an empty packet. |
| 27199 | |
| 27200 | @end table |
| 27201 | |
| 27202 | @node Register Packet Format |
| 27203 | @section Register Packet Format |
| 27204 | |
| 27205 | The following @code{g}/@code{G} packets have previously been defined. |
| 27206 | In the below, some thirty-two bit registers are transferred as |
| 27207 | sixty-four bits. Those registers should be zero/sign extended (which?) |
| 27208 | to fill the space allocated. Register bytes are transferred in target |
| 27209 | byte order. The two nibbles within a register byte are transferred |
| 27210 | most-significant - least-significant. |
| 27211 | |
| 27212 | @table @r |
| 27213 | |
| 27214 | @item MIPS32 |
| 27215 | |
| 27216 | All registers are transferred as thirty-two bit quantities in the order: |
| 27217 | 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point |
| 27218 | registers; fsr; fir; fp. |
| 27219 | |
| 27220 | @item MIPS64 |
| 27221 | |
| 27222 | All registers are transferred as sixty-four bit quantities (including |
| 27223 | thirty-two bit registers such as @code{sr}). The ordering is the same |
| 27224 | as @code{MIPS32}. |
| 27225 | |
| 27226 | @end table |
| 27227 | |
| 27228 | @node Tracepoint Packets |
| 27229 | @section Tracepoint Packets |
| 27230 | @cindex tracepoint packets |
| 27231 | @cindex packets, tracepoint |
| 27232 | |
| 27233 | Here we describe the packets @value{GDBN} uses to implement |
| 27234 | tracepoints (@pxref{Tracepoints}). |
| 27235 | |
| 27236 | @table @samp |
| 27237 | |
| 27238 | @item QTDP:@var{n}:@var{addr}:@var{ena}:@var{step}:@var{pass}@r{[}-@r{]} |
| 27239 | Create a new tracepoint, number @var{n}, at @var{addr}. If @var{ena} |
| 27240 | is @samp{E}, then the tracepoint is enabled; if it is @samp{D}, then |
| 27241 | the tracepoint is disabled. @var{step} is the tracepoint's step |
| 27242 | count, and @var{pass} is its pass count. If the trailing @samp{-} is |
| 27243 | present, further @samp{QTDP} packets will follow to specify this |
| 27244 | tracepoint's actions. |
| 27245 | |
| 27246 | Replies: |
| 27247 | @table @samp |
| 27248 | @item OK |
| 27249 | The packet was understood and carried out. |
| 27250 | @item |
| 27251 | The packet was not recognized. |
| 27252 | @end table |
| 27253 | |
| 27254 | @item QTDP:-@var{n}:@var{addr}:@r{[}S@r{]}@var{action}@dots{}@r{[}-@r{]} |
| 27255 | Define actions to be taken when a tracepoint is hit. @var{n} and |
| 27256 | @var{addr} must be the same as in the initial @samp{QTDP} packet for |
| 27257 | this tracepoint. This packet may only be sent immediately after |
| 27258 | another @samp{QTDP} packet that ended with a @samp{-}. If the |
| 27259 | trailing @samp{-} is present, further @samp{QTDP} packets will follow, |
| 27260 | specifying more actions for this tracepoint. |
| 27261 | |
| 27262 | In the series of action packets for a given tracepoint, at most one |
| 27263 | can have an @samp{S} before its first @var{action}. If such a packet |
| 27264 | is sent, it and the following packets define ``while-stepping'' |
| 27265 | actions. Any prior packets define ordinary actions --- that is, those |
| 27266 | taken when the tracepoint is first hit. If no action packet has an |
| 27267 | @samp{S}, then all the packets in the series specify ordinary |
| 27268 | tracepoint actions. |
| 27269 | |
| 27270 | The @samp{@var{action}@dots{}} portion of the packet is a series of |
| 27271 | actions, concatenated without separators. Each action has one of the |
| 27272 | following forms: |
| 27273 | |
| 27274 | @table @samp |
| 27275 | |
| 27276 | @item R @var{mask} |
| 27277 | Collect the registers whose bits are set in @var{mask}. @var{mask} is |
| 27278 | a hexadecimal number whose @var{i}'th bit is set if register number |
| 27279 | @var{i} should be collected. (The least significant bit is numbered |
| 27280 | zero.) Note that @var{mask} may be any number of digits long; it may |
| 27281 | not fit in a 32-bit word. |
| 27282 | |
| 27283 | @item M @var{basereg},@var{offset},@var{len} |
| 27284 | Collect @var{len} bytes of memory starting at the address in register |
| 27285 | number @var{basereg}, plus @var{offset}. If @var{basereg} is |
| 27286 | @samp{-1}, then the range has a fixed address: @var{offset} is the |
| 27287 | address of the lowest byte to collect. The @var{basereg}, |
| 27288 | @var{offset}, and @var{len} parameters are all unsigned hexadecimal |
| 27289 | values (the @samp{-1} value for @var{basereg} is a special case). |
| 27290 | |
| 27291 | @item X @var{len},@var{expr} |
| 27292 | Evaluate @var{expr}, whose length is @var{len}, and collect memory as |
| 27293 | it directs. @var{expr} is an agent expression, as described in |
| 27294 | @ref{Agent Expressions}. Each byte of the expression is encoded as a |
| 27295 | two-digit hex number in the packet; @var{len} is the number of bytes |
| 27296 | in the expression (and thus one-half the number of hex digits in the |
| 27297 | packet). |
| 27298 | |
| 27299 | @end table |
| 27300 | |
| 27301 | Any number of actions may be packed together in a single @samp{QTDP} |
| 27302 | packet, as long as the packet does not exceed the maximum packet |
| 27303 | length (400 bytes, for many stubs). There may be only one @samp{R} |
| 27304 | action per tracepoint, and it must precede any @samp{M} or @samp{X} |
| 27305 | actions. Any registers referred to by @samp{M} and @samp{X} actions |
| 27306 | must be collected by a preceding @samp{R} action. (The |
| 27307 | ``while-stepping'' actions are treated as if they were attached to a |
| 27308 | separate tracepoint, as far as these restrictions are concerned.) |
| 27309 | |
| 27310 | Replies: |
| 27311 | @table @samp |
| 27312 | @item OK |
| 27313 | The packet was understood and carried out. |
| 27314 | @item |
| 27315 | The packet was not recognized. |
| 27316 | @end table |
| 27317 | |
| 27318 | @item QTFrame:@var{n} |
| 27319 | Select the @var{n}'th tracepoint frame from the buffer, and use the |
| 27320 | register and memory contents recorded there to answer subsequent |
| 27321 | request packets from @value{GDBN}. |
| 27322 | |
| 27323 | A successful reply from the stub indicates that the stub has found the |
| 27324 | requested frame. The response is a series of parts, concatenated |
| 27325 | without separators, describing the frame we selected. Each part has |
| 27326 | one of the following forms: |
| 27327 | |
| 27328 | @table @samp |
| 27329 | @item F @var{f} |
| 27330 | The selected frame is number @var{n} in the trace frame buffer; |
| 27331 | @var{f} is a hexadecimal number. If @var{f} is @samp{-1}, then there |
| 27332 | was no frame matching the criteria in the request packet. |
| 27333 | |
| 27334 | @item T @var{t} |
| 27335 | The selected trace frame records a hit of tracepoint number @var{t}; |
| 27336 | @var{t} is a hexadecimal number. |
| 27337 | |
| 27338 | @end table |
| 27339 | |
| 27340 | @item QTFrame:pc:@var{addr} |
| 27341 | Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the |
| 27342 | currently selected frame whose PC is @var{addr}; |
| 27343 | @var{addr} is a hexadecimal number. |
| 27344 | |
| 27345 | @item QTFrame:tdp:@var{t} |
| 27346 | Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the |
| 27347 | currently selected frame that is a hit of tracepoint @var{t}; @var{t} |
| 27348 | is a hexadecimal number. |
| 27349 | |
| 27350 | @item QTFrame:range:@var{start}:@var{end} |
| 27351 | Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the |
| 27352 | currently selected frame whose PC is between @var{start} (inclusive) |
| 27353 | and @var{end} (exclusive); @var{start} and @var{end} are hexadecimal |
| 27354 | numbers. |
| 27355 | |
| 27356 | @item QTFrame:outside:@var{start}:@var{end} |
| 27357 | Like @samp{QTFrame:range:@var{start}:@var{end}}, but select the first |
| 27358 | frame @emph{outside} the given range of addresses. |
| 27359 | |
| 27360 | @item QTStart |
| 27361 | Begin the tracepoint experiment. Begin collecting data from tracepoint |
| 27362 | hits in the trace frame buffer. |
| 27363 | |
| 27364 | @item QTStop |
| 27365 | End the tracepoint experiment. Stop collecting trace frames. |
| 27366 | |
| 27367 | @item QTinit |
| 27368 | Clear the table of tracepoints, and empty the trace frame buffer. |
| 27369 | |
| 27370 | @item QTro:@var{start1},@var{end1}:@var{start2},@var{end2}:@dots{} |
| 27371 | Establish the given ranges of memory as ``transparent''. The stub |
| 27372 | will answer requests for these ranges from memory's current contents, |
| 27373 | if they were not collected as part of the tracepoint hit. |
| 27374 | |
| 27375 | @value{GDBN} uses this to mark read-only regions of memory, like those |
| 27376 | containing program code. Since these areas never change, they should |
| 27377 | still have the same contents they did when the tracepoint was hit, so |
| 27378 | there's no reason for the stub to refuse to provide their contents. |
| 27379 | |
| 27380 | @item qTStatus |
| 27381 | Ask the stub if there is a trace experiment running right now. |
| 27382 | |
| 27383 | Replies: |
| 27384 | @table @samp |
| 27385 | @item T0 |
| 27386 | There is no trace experiment running. |
| 27387 | @item T1 |
| 27388 | There is a trace experiment running. |
| 27389 | @end table |
| 27390 | |
| 27391 | @end table |
| 27392 | |
| 27393 | |
| 27394 | @node Host I/O Packets |
| 27395 | @section Host I/O Packets |
| 27396 | @cindex Host I/O, remote protocol |
| 27397 | @cindex file transfer, remote protocol |
| 27398 | |
| 27399 | The @dfn{Host I/O} packets allow @value{GDBN} to perform I/O |
| 27400 | operations on the far side of a remote link. For example, Host I/O is |
| 27401 | used to upload and download files to a remote target with its own |
| 27402 | filesystem. Host I/O uses the same constant values and data structure |
| 27403 | layout as the target-initiated File-I/O protocol. However, the |
| 27404 | Host I/O packets are structured differently. The target-initiated |
| 27405 | protocol relies on target memory to store parameters and buffers. |
| 27406 | Host I/O requests are initiated by @value{GDBN}, and the |
| 27407 | target's memory is not involved. @xref{File-I/O Remote Protocol |
| 27408 | Extension}, for more details on the target-initiated protocol. |
| 27409 | |
| 27410 | The Host I/O request packets all encode a single operation along with |
| 27411 | its arguments. They have this format: |
| 27412 | |
| 27413 | @table @samp |
| 27414 | |
| 27415 | @item vFile:@var{operation}: @var{parameter}@dots{} |
| 27416 | @var{operation} is the name of the particular request; the target |
| 27417 | should compare the entire packet name up to the second colon when checking |
| 27418 | for a supported operation. The format of @var{parameter} depends on |
| 27419 | the operation. Numbers are always passed in hexadecimal. Negative |
| 27420 | numbers have an explicit minus sign (i.e.@: two's complement is not |
| 27421 | used). Strings (e.g.@: filenames) are encoded as a series of |
| 27422 | hexadecimal bytes. The last argument to a system call may be a |
| 27423 | buffer of escaped binary data (@pxref{Binary Data}). |
| 27424 | |
| 27425 | @end table |
| 27426 | |
| 27427 | The valid responses to Host I/O packets are: |
| 27428 | |
| 27429 | @table @samp |
| 27430 | |
| 27431 | @item F @var{result} [, @var{errno}] [; @var{attachment}] |
| 27432 | @var{result} is the integer value returned by this operation, usually |
| 27433 | non-negative for success and -1 for errors. If an error has occured, |
| 27434 | @var{errno} will be included in the result. @var{errno} will have a |
| 27435 | value defined by the File-I/O protocol (@pxref{Errno Values}). For |
| 27436 | operations which return data, @var{attachment} supplies the data as a |
| 27437 | binary buffer. Binary buffers in response packets are escaped in the |
| 27438 | normal way (@pxref{Binary Data}). See the individual packet |
| 27439 | documentation for the interpretation of @var{result} and |
| 27440 | @var{attachment}. |
| 27441 | |
| 27442 | @item |
| 27443 | An empty response indicates that this operation is not recognized. |
| 27444 | |
| 27445 | @end table |
| 27446 | |
| 27447 | These are the supported Host I/O operations: |
| 27448 | |
| 27449 | @table @samp |
| 27450 | @item vFile:open: @var{pathname}, @var{flags}, @var{mode} |
| 27451 | Open a file at @var{pathname} and return a file descriptor for it, or |
| 27452 | return -1 if an error occurs. @var{pathname} is a string, |
| 27453 | @var{flags} is an integer indicating a mask of open flags |
| 27454 | (@pxref{Open Flags}), and @var{mode} is an integer indicating a mask |
| 27455 | of mode bits to use if the file is created (@pxref{mode_t Values}). |
| 27456 | @xref{open}, for details of the open flags and mode values. |
| 27457 | |
| 27458 | @item vFile:close: @var{fd} |
| 27459 | Close the open file corresponding to @var{fd} and return 0, or |
| 27460 | -1 if an error occurs. |
| 27461 | |
| 27462 | @item vFile:pread: @var{fd}, @var{count}, @var{offset} |
| 27463 | Read data from the open file corresponding to @var{fd}. Up to |
| 27464 | @var{count} bytes will be read from the file, starting at @var{offset} |
| 27465 | relative to the start of the file. The target may read fewer bytes; |
| 27466 | common reasons include packet size limits and an end-of-file |
| 27467 | condition. The number of bytes read is returned. Zero should only be |
| 27468 | returned for a successful read at the end of the file, or if |
| 27469 | @var{count} was zero. |
| 27470 | |
| 27471 | The data read should be returned as a binary attachment on success. |
| 27472 | If zero bytes were read, the response should include an empty binary |
| 27473 | attachment (i.e.@: a trailing semicolon). The return value is the |
| 27474 | number of target bytes read; the binary attachment may be longer if |
| 27475 | some characters were escaped. |
| 27476 | |
| 27477 | @item vFile:pwrite: @var{fd}, @var{offset}, @var{data} |
| 27478 | Write @var{data} (a binary buffer) to the open file corresponding |
| 27479 | to @var{fd}. Start the write at @var{offset} from the start of the |
| 27480 | file. Unlike many @code{write} system calls, there is no |
| 27481 | separate @var{count} argument; the length of @var{data} in the |
| 27482 | packet is used. @samp{vFile:write} returns the number of bytes written, |
| 27483 | which may be shorter than the length of @var{data}, or -1 if an |
| 27484 | error occurred. |
| 27485 | |
| 27486 | @item vFile:unlink: @var{pathname} |
| 27487 | Delete the file at @var{pathname} on the target. Return 0, |
| 27488 | or -1 if an error occurs. @var{pathname} is a string. |
| 27489 | |
| 27490 | @end table |
| 27491 | |
| 27492 | @node Interrupts |
| 27493 | @section Interrupts |
| 27494 | @cindex interrupts (remote protocol) |
| 27495 | |
| 27496 | When a program on the remote target is running, @value{GDBN} may |
| 27497 | attempt to interrupt it by sending a @samp{Ctrl-C} or a @code{BREAK}, |
| 27498 | control of which is specified via @value{GDBN}'s @samp{remotebreak} |
| 27499 | setting (@pxref{set remotebreak}). |
| 27500 | |
| 27501 | The precise meaning of @code{BREAK} is defined by the transport |
| 27502 | mechanism and may, in fact, be undefined. @value{GDBN} does not |
| 27503 | currently define a @code{BREAK} mechanism for any of the network |
| 27504 | interfaces except for TCP, in which case @value{GDBN} sends the |
| 27505 | @code{telnet} BREAK sequence. |
| 27506 | |
| 27507 | @samp{Ctrl-C}, on the other hand, is defined and implemented for all |
| 27508 | transport mechanisms. It is represented by sending the single byte |
| 27509 | @code{0x03} without any of the usual packet overhead described in |
| 27510 | the Overview section (@pxref{Overview}). When a @code{0x03} byte is |
| 27511 | transmitted as part of a packet, it is considered to be packet data |
| 27512 | and does @emph{not} represent an interrupt. E.g., an @samp{X} packet |
| 27513 | (@pxref{X packet}), used for binary downloads, may include an unescaped |
| 27514 | @code{0x03} as part of its packet. |
| 27515 | |
| 27516 | Stubs are not required to recognize these interrupt mechanisms and the |
| 27517 | precise meaning associated with receipt of the interrupt is |
| 27518 | implementation defined. If the target supports debugging of multiple |
| 27519 | threads and/or processes, it should attempt to interrupt all |
| 27520 | currently-executing threads and processes. |
| 27521 | If the stub is successful at interrupting the |
| 27522 | running program, it should send one of the stop |
| 27523 | reply packets (@pxref{Stop Reply Packets}) to @value{GDBN} as a result |
| 27524 | of successfully stopping the program in all-stop mode, and a stop reply |
| 27525 | for each stopped thread in non-stop mode. |
| 27526 | Interrupts received while the |
| 27527 | program is stopped are discarded. |
| 27528 | |
| 27529 | @node Notification Packets |
| 27530 | @section Notification Packets |
| 27531 | @cindex notification packets |
| 27532 | @cindex packets, notification |
| 27533 | |
| 27534 | The @value{GDBN} remote serial protocol includes @dfn{notifications}, |
| 27535 | packets that require no acknowledgment. Both the GDB and the stub |
| 27536 | may send notifications (although the only notifications defined at |
| 27537 | present are sent by the stub). Notifications carry information |
| 27538 | without incurring the round-trip latency of an acknowledgment, and so |
| 27539 | are useful for low-impact communications where occasional packet loss |
| 27540 | is not a problem. |
| 27541 | |
| 27542 | A notification packet has the form @samp{% @var{data} # |
| 27543 | @var{checksum}}, where @var{data} is the content of the notification, |
| 27544 | and @var{checksum} is a checksum of @var{data}, computed and formatted |
| 27545 | as for ordinary @value{GDBN} packets. A notification's @var{data} |
| 27546 | never contains @samp{$}, @samp{%} or @samp{#} characters. Upon |
| 27547 | receiving a notification, the recipient sends no @samp{+} or @samp{-} |
| 27548 | to acknowledge the notification's receipt or to report its corruption. |
| 27549 | |
| 27550 | Every notification's @var{data} begins with a name, which contains no |
| 27551 | colon characters, followed by a colon character. |
| 27552 | |
| 27553 | Recipients should silently ignore corrupted notifications and |
| 27554 | notifications they do not understand. Recipients should restart |
| 27555 | timeout periods on receipt of a well-formed notification, whether or |
| 27556 | not they understand it. |
| 27557 | |
| 27558 | Senders should only send the notifications described here when this |
| 27559 | protocol description specifies that they are permitted. In the |
| 27560 | future, we may extend the protocol to permit existing notifications in |
| 27561 | new contexts; this rule helps older senders avoid confusing newer |
| 27562 | recipients. |
| 27563 | |
| 27564 | (Older versions of @value{GDBN} ignore bytes received until they see |
| 27565 | the @samp{$} byte that begins an ordinary packet, so new stubs may |
| 27566 | transmit notifications without fear of confusing older clients. There |
| 27567 | are no notifications defined for @value{GDBN} to send at the moment, but we |
| 27568 | assume that most older stubs would ignore them, as well.) |
| 27569 | |
| 27570 | The following notification packets from the stub to @value{GDBN} are |
| 27571 | defined: |
| 27572 | |
| 27573 | @table @samp |
| 27574 | @item Stop: @var{reply} |
| 27575 | Report an asynchronous stop event in non-stop mode. |
| 27576 | The @var{reply} has the form of a stop reply, as |
| 27577 | described in @ref{Stop Reply Packets}. Refer to @ref{Remote Non-Stop}, |
| 27578 | for information on how these notifications are acknowledged by |
| 27579 | @value{GDBN}. |
| 27580 | @end table |
| 27581 | |
| 27582 | @node Remote Non-Stop |
| 27583 | @section Remote Protocol Support for Non-Stop Mode |
| 27584 | |
| 27585 | @value{GDBN}'s remote protocol supports non-stop debugging of |
| 27586 | multi-threaded programs, as described in @ref{Non-Stop Mode}. If the stub |
| 27587 | supports non-stop mode, it should report that to @value{GDBN} by including |
| 27588 | @samp{QNonStop+} in its @samp{qSupported} response (@pxref{qSupported}). |
| 27589 | |
| 27590 | @value{GDBN} typically sends a @samp{QNonStop} packet only when |
| 27591 | establishing a new connection with the stub. Entering non-stop mode |
| 27592 | does not alter the state of any currently-running threads, but targets |
| 27593 | must stop all threads in any already-attached processes when entering |
| 27594 | all-stop mode. @value{GDBN} uses the @samp{?} packet as necessary to |
| 27595 | probe the target state after a mode change. |
| 27596 | |
| 27597 | In non-stop mode, when an attached process encounters an event that |
| 27598 | would otherwise be reported with a stop reply, it uses the |
| 27599 | asynchronous notification mechanism (@pxref{Notification Packets}) to |
| 27600 | inform @value{GDBN}. In contrast to all-stop mode, where all threads |
| 27601 | in all processes are stopped when a stop reply is sent, in non-stop |
| 27602 | mode only the thread reporting the stop event is stopped. That is, |
| 27603 | when reporting a @samp{S} or @samp{T} response to indicate completion |
| 27604 | of a step operation, hitting a breakpoint, or a fault, only the |
| 27605 | affected thread is stopped; any other still-running threads continue |
| 27606 | to run. When reporting a @samp{W} or @samp{X} response, all running |
| 27607 | threads belonging to other attached processes continue to run. |
| 27608 | |
| 27609 | Only one stop reply notification at a time may be pending; if |
| 27610 | additional stop events occur before @value{GDBN} has acknowledged the |
| 27611 | previous notification, they must be queued by the stub for later |
| 27612 | synchronous transmission in response to @samp{vStopped} packets from |
| 27613 | @value{GDBN}. Because the notification mechanism is unreliable, |
| 27614 | the stub is permitted to resend a stop reply notification |
| 27615 | if it believes @value{GDBN} may not have received it. @value{GDBN} |
| 27616 | ignores additional stop reply notifications received before it has |
| 27617 | finished processing a previous notification and the stub has completed |
| 27618 | sending any queued stop events. |
| 27619 | |
| 27620 | Otherwise, @value{GDBN} must be prepared to receive a stop reply |
| 27621 | notification at any time. Specifically, they may appear when |
| 27622 | @value{GDBN} is not otherwise reading input from the stub, or when |
| 27623 | @value{GDBN} is expecting to read a normal synchronous response or a |
| 27624 | @samp{+}/@samp{-} acknowledgment to a packet it has sent. |
| 27625 | Notification packets are distinct from any other communication from |
| 27626 | the stub so there is no ambiguity. |
| 27627 | |
| 27628 | After receiving a stop reply notification, @value{GDBN} shall |
| 27629 | acknowledge it by sending a @samp{vStopped} packet (@pxref{vStopped packet}) |
| 27630 | as a regular, synchronous request to the stub. Such acknowledgment |
| 27631 | is not required to happen immediately, as @value{GDBN} is permitted to |
| 27632 | send other, unrelated packets to the stub first, which the stub should |
| 27633 | process normally. |
| 27634 | |
| 27635 | Upon receiving a @samp{vStopped} packet, if the stub has other queued |
| 27636 | stop events to report to @value{GDBN}, it shall respond by sending a |
| 27637 | normal stop reply response. @value{GDBN} shall then send another |
| 27638 | @samp{vStopped} packet to solicit further responses; again, it is |
| 27639 | permitted to send other, unrelated packets as well which the stub |
| 27640 | should process normally. |
| 27641 | |
| 27642 | If the stub receives a @samp{vStopped} packet and there are no |
| 27643 | additional stop events to report, the stub shall return an @samp{OK} |
| 27644 | response. At this point, if further stop events occur, the stub shall |
| 27645 | send a new stop reply notification, @value{GDBN} shall accept the |
| 27646 | notification, and the process shall be repeated. |
| 27647 | |
| 27648 | In non-stop mode, the target shall respond to the @samp{?} packet as |
| 27649 | follows. First, any incomplete stop reply notification/@samp{vStopped} |
| 27650 | sequence in progress is abandoned. The target must begin a new |
| 27651 | sequence reporting stop events for all stopped threads, whether or not |
| 27652 | it has previously reported those events to @value{GDBN}. The first |
| 27653 | stop reply is sent as a synchronous reply to the @samp{?} packet, and |
| 27654 | subsequent stop replies are sent as responses to @samp{vStopped} packets |
| 27655 | using the mechanism described above. The target must not send |
| 27656 | asynchronous stop reply notifications until the sequence is complete. |
| 27657 | If all threads are running when the target receives the @samp{?} packet, |
| 27658 | or if the target is not attached to any process, it shall respond |
| 27659 | @samp{OK}. |
| 27660 | |
| 27661 | @node Packet Acknowledgment |
| 27662 | @section Packet Acknowledgment |
| 27663 | |
| 27664 | @cindex acknowledgment, for @value{GDBN} remote |
| 27665 | @cindex packet acknowledgment, for @value{GDBN} remote |
| 27666 | By default, when either the host or the target machine receives a packet, |
| 27667 | the first response expected is an acknowledgment: either @samp{+} (to indicate |
| 27668 | the package was received correctly) or @samp{-} (to request retransmission). |
| 27669 | This mechanism allows the @value{GDBN} remote protocol to operate over |
| 27670 | unreliable transport mechanisms, such as a serial line. |
| 27671 | |
| 27672 | In cases where the transport mechanism is itself reliable (such as a pipe or |
| 27673 | TCP connection), the @samp{+}/@samp{-} acknowledgments are redundant. |
| 27674 | It may be desirable to disable them in that case to reduce communication |
| 27675 | overhead, or for other reasons. This can be accomplished by means of the |
| 27676 | @samp{QStartNoAckMode} packet; @pxref{QStartNoAckMode}. |
| 27677 | |
| 27678 | When in no-acknowledgment mode, neither the stub nor @value{GDBN} shall send or |
| 27679 | expect @samp{+}/@samp{-} protocol acknowledgments. The packet |
| 27680 | and response format still includes the normal checksum, as described in |
| 27681 | @ref{Overview}, but the checksum may be ignored by the receiver. |
| 27682 | |
| 27683 | If the stub supports @samp{QStartNoAckMode} and prefers to operate in |
| 27684 | no-acknowledgment mode, it should report that to @value{GDBN} |
| 27685 | by including @samp{QStartNoAckMode+} in its response to @samp{qSupported}; |
| 27686 | @pxref{qSupported}. |
| 27687 | If @value{GDBN} also supports @samp{QStartNoAckMode} and it has not been |
| 27688 | disabled via the @code{set remote noack-packet off} command |
| 27689 | (@pxref{Remote Configuration}), |
| 27690 | @value{GDBN} may then send a @samp{QStartNoAckMode} packet to the stub. |
| 27691 | Only then may the stub actually turn off packet acknowledgments. |
| 27692 | @value{GDBN} sends a final @samp{+} acknowledgment of the stub's @samp{OK} |
| 27693 | response, which can be safely ignored by the stub. |
| 27694 | |
| 27695 | Note that @code{set remote noack-packet} command only affects negotiation |
| 27696 | between @value{GDBN} and the stub when subsequent connections are made; |
| 27697 | it does not affect the protocol acknowledgment state for any current |
| 27698 | connection. |
| 27699 | Since @samp{+}/@samp{-} acknowledgments are enabled by default when a |
| 27700 | new connection is established, |
| 27701 | there is also no protocol request to re-enable the acknowledgments |
| 27702 | for the current connection, once disabled. |
| 27703 | |
| 27704 | @node Examples |
| 27705 | @section Examples |
| 27706 | |
| 27707 | Example sequence of a target being re-started. Notice how the restart |
| 27708 | does not get any direct output: |
| 27709 | |
| 27710 | @smallexample |
| 27711 | -> @code{R00} |
| 27712 | <- @code{+} |
| 27713 | @emph{target restarts} |
| 27714 | -> @code{?} |
| 27715 | <- @code{+} |
| 27716 | <- @code{T001:1234123412341234} |
| 27717 | -> @code{+} |
| 27718 | @end smallexample |
| 27719 | |
| 27720 | Example sequence of a target being stepped by a single instruction: |
| 27721 | |
| 27722 | @smallexample |
| 27723 | -> @code{G1445@dots{}} |
| 27724 | <- @code{+} |
| 27725 | -> @code{s} |
| 27726 | <- @code{+} |
| 27727 | @emph{time passes} |
| 27728 | <- @code{T001:1234123412341234} |
| 27729 | -> @code{+} |
| 27730 | -> @code{g} |
| 27731 | <- @code{+} |
| 27732 | <- @code{1455@dots{}} |
| 27733 | -> @code{+} |
| 27734 | @end smallexample |
| 27735 | |
| 27736 | @node File-I/O Remote Protocol Extension |
| 27737 | @section File-I/O Remote Protocol Extension |
| 27738 | @cindex File-I/O remote protocol extension |
| 27739 | |
| 27740 | @menu |
| 27741 | * File-I/O Overview:: |
| 27742 | * Protocol Basics:: |
| 27743 | * The F Request Packet:: |
| 27744 | * The F Reply Packet:: |
| 27745 | * The Ctrl-C Message:: |
| 27746 | * Console I/O:: |
| 27747 | * List of Supported Calls:: |
| 27748 | * Protocol-specific Representation of Datatypes:: |
| 27749 | * Constants:: |
| 27750 | * File-I/O Examples:: |
| 27751 | @end menu |
| 27752 | |
| 27753 | @node File-I/O Overview |
| 27754 | @subsection File-I/O Overview |
| 27755 | @cindex file-i/o overview |
| 27756 | |
| 27757 | The @dfn{File I/O remote protocol extension} (short: File-I/O) allows the |
| 27758 | target to use the host's file system and console I/O to perform various |
| 27759 | system calls. System calls on the target system are translated into a |
| 27760 | remote protocol packet to the host system, which then performs the needed |
| 27761 | actions and returns a response packet to the target system. |
| 27762 | This simulates file system operations even on targets that lack file systems. |
| 27763 | |
| 27764 | The protocol is defined to be independent of both the host and target systems. |
| 27765 | It uses its own internal representation of datatypes and values. Both |
| 27766 | @value{GDBN} and the target's @value{GDBN} stub are responsible for |
| 27767 | translating the system-dependent value representations into the internal |
| 27768 | protocol representations when data is transmitted. |
| 27769 | |
| 27770 | The communication is synchronous. A system call is possible only when |
| 27771 | @value{GDBN} is waiting for a response from the @samp{C}, @samp{c}, @samp{S} |
| 27772 | or @samp{s} packets. While @value{GDBN} handles the request for a system call, |
| 27773 | the target is stopped to allow deterministic access to the target's |
| 27774 | memory. Therefore File-I/O is not interruptible by target signals. On |
| 27775 | the other hand, it is possible to interrupt File-I/O by a user interrupt |
| 27776 | (@samp{Ctrl-C}) within @value{GDBN}. |
| 27777 | |
| 27778 | The target's request to perform a host system call does not finish |
| 27779 | the latest @samp{C}, @samp{c}, @samp{S} or @samp{s} action. That means, |
| 27780 | after finishing the system call, the target returns to continuing the |
| 27781 | previous activity (continue, step). No additional continue or step |
| 27782 | request from @value{GDBN} is required. |
| 27783 | |
| 27784 | @smallexample |
| 27785 | (@value{GDBP}) continue |
| 27786 | <- target requests 'system call X' |
| 27787 | target is stopped, @value{GDBN} executes system call |
| 27788 | -> @value{GDBN} returns result |
| 27789 | ... target continues, @value{GDBN} returns to wait for the target |
| 27790 | <- target hits breakpoint and sends a Txx packet |
| 27791 | @end smallexample |
| 27792 | |
| 27793 | The protocol only supports I/O on the console and to regular files on |
| 27794 | the host file system. Character or block special devices, pipes, |
| 27795 | named pipes, sockets or any other communication method on the host |
| 27796 | system are not supported by this protocol. |
| 27797 | |
| 27798 | File I/O is not supported in non-stop mode. |
| 27799 | |
| 27800 | @node Protocol Basics |
| 27801 | @subsection Protocol Basics |
| 27802 | @cindex protocol basics, file-i/o |
| 27803 | |
| 27804 | The File-I/O protocol uses the @code{F} packet as the request as well |
| 27805 | as reply packet. Since a File-I/O system call can only occur when |
| 27806 | @value{GDBN} is waiting for a response from the continuing or stepping target, |
| 27807 | the File-I/O request is a reply that @value{GDBN} has to expect as a result |
| 27808 | of a previous @samp{C}, @samp{c}, @samp{S} or @samp{s} packet. |
| 27809 | This @code{F} packet contains all information needed to allow @value{GDBN} |
| 27810 | to call the appropriate host system call: |
| 27811 | |
| 27812 | @itemize @bullet |
| 27813 | @item |
| 27814 | A unique identifier for the requested system call. |
| 27815 | |
| 27816 | @item |
| 27817 | All parameters to the system call. Pointers are given as addresses |
| 27818 | in the target memory address space. Pointers to strings are given as |
| 27819 | pointer/length pair. Numerical values are given as they are. |
| 27820 | Numerical control flags are given in a protocol-specific representation. |
| 27821 | |
| 27822 | @end itemize |
| 27823 | |
| 27824 | At this point, @value{GDBN} has to perform the following actions. |
| 27825 | |
| 27826 | @itemize @bullet |
| 27827 | @item |
| 27828 | If the parameters include pointer values to data needed as input to a |
| 27829 | system call, @value{GDBN} requests this data from the target with a |
| 27830 | standard @code{m} packet request. This additional communication has to be |
| 27831 | expected by the target implementation and is handled as any other @code{m} |
| 27832 | packet. |
| 27833 | |
| 27834 | @item |
| 27835 | @value{GDBN} translates all value from protocol representation to host |
| 27836 | representation as needed. Datatypes are coerced into the host types. |
| 27837 | |
| 27838 | @item |
| 27839 | @value{GDBN} calls the system call. |
| 27840 | |
| 27841 | @item |
| 27842 | It then coerces datatypes back to protocol representation. |
| 27843 | |
| 27844 | @item |
| 27845 | If the system call is expected to return data in buffer space specified |
| 27846 | by pointer parameters to the call, the data is transmitted to the |
| 27847 | target using a @code{M} or @code{X} packet. This packet has to be expected |
| 27848 | by the target implementation and is handled as any other @code{M} or @code{X} |
| 27849 | packet. |
| 27850 | |
| 27851 | @end itemize |
| 27852 | |
| 27853 | Eventually @value{GDBN} replies with another @code{F} packet which contains all |
| 27854 | necessary information for the target to continue. This at least contains |
| 27855 | |
| 27856 | @itemize @bullet |
| 27857 | @item |
| 27858 | Return value. |
| 27859 | |
| 27860 | @item |
| 27861 | @code{errno}, if has been changed by the system call. |
| 27862 | |
| 27863 | @item |
| 27864 | ``Ctrl-C'' flag. |
| 27865 | |
| 27866 | @end itemize |
| 27867 | |
| 27868 | After having done the needed type and value coercion, the target continues |
| 27869 | the latest continue or step action. |
| 27870 | |
| 27871 | @node The F Request Packet |
| 27872 | @subsection The @code{F} Request Packet |
| 27873 | @cindex file-i/o request packet |
| 27874 | @cindex @code{F} request packet |
| 27875 | |
| 27876 | The @code{F} request packet has the following format: |
| 27877 | |
| 27878 | @table @samp |
| 27879 | @item F@var{call-id},@var{parameter@dots{}} |
| 27880 | |
| 27881 | @var{call-id} is the identifier to indicate the host system call to be called. |
| 27882 | This is just the name of the function. |
| 27883 | |
| 27884 | @var{parameter@dots{}} are the parameters to the system call. |
| 27885 | Parameters are hexadecimal integer values, either the actual values in case |
| 27886 | of scalar datatypes, pointers to target buffer space in case of compound |
| 27887 | datatypes and unspecified memory areas, or pointer/length pairs in case |
| 27888 | of string parameters. These are appended to the @var{call-id} as a |
| 27889 | comma-delimited list. All values are transmitted in ASCII |
| 27890 | string representation, pointer/length pairs separated by a slash. |
| 27891 | |
| 27892 | @end table |
| 27893 | |
| 27894 | |
| 27895 | |
| 27896 | @node The F Reply Packet |
| 27897 | @subsection The @code{F} Reply Packet |
| 27898 | @cindex file-i/o reply packet |
| 27899 | @cindex @code{F} reply packet |
| 27900 | |
| 27901 | The @code{F} reply packet has the following format: |
| 27902 | |
| 27903 | @table @samp |
| 27904 | |
| 27905 | @item F@var{retcode},@var{errno},@var{Ctrl-C flag};@var{call-specific attachment} |
| 27906 | |
| 27907 | @var{retcode} is the return code of the system call as hexadecimal value. |
| 27908 | |
| 27909 | @var{errno} is the @code{errno} set by the call, in protocol-specific |
| 27910 | representation. |
| 27911 | This parameter can be omitted if the call was successful. |
| 27912 | |
| 27913 | @var{Ctrl-C flag} is only sent if the user requested a break. In this |
| 27914 | case, @var{errno} must be sent as well, even if the call was successful. |
| 27915 | The @var{Ctrl-C flag} itself consists of the character @samp{C}: |
| 27916 | |
| 27917 | @smallexample |
| 27918 | F0,0,C |
| 27919 | @end smallexample |
| 27920 | |
| 27921 | @noindent |
| 27922 | or, if the call was interrupted before the host call has been performed: |
| 27923 | |
| 27924 | @smallexample |
| 27925 | F-1,4,C |
| 27926 | @end smallexample |
| 27927 | |
| 27928 | @noindent |
| 27929 | assuming 4 is the protocol-specific representation of @code{EINTR}. |
| 27930 | |
| 27931 | @end table |
| 27932 | |
| 27933 | |
| 27934 | @node The Ctrl-C Message |
| 27935 | @subsection The @samp{Ctrl-C} Message |
| 27936 | @cindex ctrl-c message, in file-i/o protocol |
| 27937 | |
| 27938 | If the @samp{Ctrl-C} flag is set in the @value{GDBN} |
| 27939 | reply packet (@pxref{The F Reply Packet}), |
| 27940 | the target should behave as if it had |
| 27941 | gotten a break message. The meaning for the target is ``system call |
| 27942 | interrupted by @code{SIGINT}''. Consequentially, the target should actually stop |
| 27943 | (as with a break message) and return to @value{GDBN} with a @code{T02} |
| 27944 | packet. |
| 27945 | |
| 27946 | It's important for the target to know in which |
| 27947 | state the system call was interrupted. There are two possible cases: |
| 27948 | |
| 27949 | @itemize @bullet |
| 27950 | @item |
| 27951 | The system call hasn't been performed on the host yet. |
| 27952 | |
| 27953 | @item |
| 27954 | The system call on the host has been finished. |
| 27955 | |
| 27956 | @end itemize |
| 27957 | |
| 27958 | These two states can be distinguished by the target by the value of the |
| 27959 | returned @code{errno}. If it's the protocol representation of @code{EINTR}, the system |
| 27960 | call hasn't been performed. This is equivalent to the @code{EINTR} handling |
| 27961 | on POSIX systems. In any other case, the target may presume that the |
| 27962 | system call has been finished --- successfully or not --- and should behave |
| 27963 | as if the break message arrived right after the system call. |
| 27964 | |
| 27965 | @value{GDBN} must behave reliably. If the system call has not been called |
| 27966 | yet, @value{GDBN} may send the @code{F} reply immediately, setting @code{EINTR} as |
| 27967 | @code{errno} in the packet. If the system call on the host has been finished |
| 27968 | before the user requests a break, the full action must be finished by |
| 27969 | @value{GDBN}. This requires sending @code{M} or @code{X} packets as necessary. |
| 27970 | The @code{F} packet may only be sent when either nothing has happened |
| 27971 | or the full action has been completed. |
| 27972 | |
| 27973 | @node Console I/O |
| 27974 | @subsection Console I/O |
| 27975 | @cindex console i/o as part of file-i/o |
| 27976 | |
| 27977 | By default and if not explicitly closed by the target system, the file |
| 27978 | descriptors 0, 1 and 2 are connected to the @value{GDBN} console. Output |
| 27979 | on the @value{GDBN} console is handled as any other file output operation |
| 27980 | (@code{write(1, @dots{})} or @code{write(2, @dots{})}). Console input is handled |
| 27981 | by @value{GDBN} so that after the target read request from file descriptor |
| 27982 | 0 all following typing is buffered until either one of the following |
| 27983 | conditions is met: |
| 27984 | |
| 27985 | @itemize @bullet |
| 27986 | @item |
| 27987 | The user types @kbd{Ctrl-c}. The behaviour is as explained above, and the |
| 27988 | @code{read} |
| 27989 | system call is treated as finished. |
| 27990 | |
| 27991 | @item |
| 27992 | The user presses @key{RET}. This is treated as end of input with a trailing |
| 27993 | newline. |
| 27994 | |
| 27995 | @item |
| 27996 | The user types @kbd{Ctrl-d}. This is treated as end of input. No trailing |
| 27997 | character (neither newline nor @samp{Ctrl-D}) is appended to the input. |
| 27998 | |
| 27999 | @end itemize |
| 28000 | |
| 28001 | If the user has typed more characters than fit in the buffer given to |
| 28002 | the @code{read} call, the trailing characters are buffered in @value{GDBN} until |
| 28003 | either another @code{read(0, @dots{})} is requested by the target, or debugging |
| 28004 | is stopped at the user's request. |
| 28005 | |
| 28006 | |
| 28007 | @node List of Supported Calls |
| 28008 | @subsection List of Supported Calls |
| 28009 | @cindex list of supported file-i/o calls |
| 28010 | |
| 28011 | @menu |
| 28012 | * open:: |
| 28013 | * close:: |
| 28014 | * read:: |
| 28015 | * write:: |
| 28016 | * lseek:: |
| 28017 | * rename:: |
| 28018 | * unlink:: |
| 28019 | * stat/fstat:: |
| 28020 | * gettimeofday:: |
| 28021 | * isatty:: |
| 28022 | * system:: |
| 28023 | @end menu |
| 28024 | |
| 28025 | @node open |
| 28026 | @unnumberedsubsubsec open |
| 28027 | @cindex open, file-i/o system call |
| 28028 | |
| 28029 | @table @asis |
| 28030 | @item Synopsis: |
| 28031 | @smallexample |
| 28032 | int open(const char *pathname, int flags); |
| 28033 | int open(const char *pathname, int flags, mode_t mode); |
| 28034 | @end smallexample |
| 28035 | |
| 28036 | @item Request: |
| 28037 | @samp{Fopen,@var{pathptr}/@var{len},@var{flags},@var{mode}} |
| 28038 | |
| 28039 | @noindent |
| 28040 | @var{flags} is the bitwise @code{OR} of the following values: |
| 28041 | |
| 28042 | @table @code |
| 28043 | @item O_CREAT |
| 28044 | If the file does not exist it will be created. The host |
| 28045 | rules apply as far as file ownership and time stamps |
| 28046 | are concerned. |
| 28047 | |
| 28048 | @item O_EXCL |
| 28049 | When used with @code{O_CREAT}, if the file already exists it is |
| 28050 | an error and open() fails. |
| 28051 | |
| 28052 | @item O_TRUNC |
| 28053 | If the file already exists and the open mode allows |
| 28054 | writing (@code{O_RDWR} or @code{O_WRONLY} is given) it will be |
| 28055 | truncated to zero length. |
| 28056 | |
| 28057 | @item O_APPEND |
| 28058 | The file is opened in append mode. |
| 28059 | |
| 28060 | @item O_RDONLY |
| 28061 | The file is opened for reading only. |
| 28062 | |
| 28063 | @item O_WRONLY |
| 28064 | The file is opened for writing only. |
| 28065 | |
| 28066 | @item O_RDWR |
| 28067 | The file is opened for reading and writing. |
| 28068 | @end table |
| 28069 | |
| 28070 | @noindent |
| 28071 | Other bits are silently ignored. |
| 28072 | |
| 28073 | |
| 28074 | @noindent |
| 28075 | @var{mode} is the bitwise @code{OR} of the following values: |
| 28076 | |
| 28077 | @table @code |
| 28078 | @item S_IRUSR |
| 28079 | User has read permission. |
| 28080 | |
| 28081 | @item S_IWUSR |
| 28082 | User has write permission. |
| 28083 | |
| 28084 | @item S_IRGRP |
| 28085 | Group has read permission. |
| 28086 | |
| 28087 | @item S_IWGRP |
| 28088 | Group has write permission. |
| 28089 | |
| 28090 | @item S_IROTH |
| 28091 | Others have read permission. |
| 28092 | |
| 28093 | @item S_IWOTH |
| 28094 | Others have write permission. |
| 28095 | @end table |
| 28096 | |
| 28097 | @noindent |
| 28098 | Other bits are silently ignored. |
| 28099 | |
| 28100 | |
| 28101 | @item Return value: |
| 28102 | @code{open} returns the new file descriptor or -1 if an error |
| 28103 | occurred. |
| 28104 | |
| 28105 | @item Errors: |
| 28106 | |
| 28107 | @table @code |
| 28108 | @item EEXIST |
| 28109 | @var{pathname} already exists and @code{O_CREAT} and @code{O_EXCL} were used. |
| 28110 | |
| 28111 | @item EISDIR |
| 28112 | @var{pathname} refers to a directory. |
| 28113 | |
| 28114 | @item EACCES |
| 28115 | The requested access is not allowed. |
| 28116 | |
| 28117 | @item ENAMETOOLONG |
| 28118 | @var{pathname} was too long. |
| 28119 | |
| 28120 | @item ENOENT |
| 28121 | A directory component in @var{pathname} does not exist. |
| 28122 | |
| 28123 | @item ENODEV |
| 28124 | @var{pathname} refers to a device, pipe, named pipe or socket. |
| 28125 | |
| 28126 | @item EROFS |
| 28127 | @var{pathname} refers to a file on a read-only filesystem and |
| 28128 | write access was requested. |
| 28129 | |
| 28130 | @item EFAULT |
| 28131 | @var{pathname} is an invalid pointer value. |
| 28132 | |
| 28133 | @item ENOSPC |
| 28134 | No space on device to create the file. |
| 28135 | |
| 28136 | @item EMFILE |
| 28137 | The process already has the maximum number of files open. |
| 28138 | |
| 28139 | @item ENFILE |
| 28140 | The limit on the total number of files open on the system |
| 28141 | has been reached. |
| 28142 | |
| 28143 | @item EINTR |
| 28144 | The call was interrupted by the user. |
| 28145 | @end table |
| 28146 | |
| 28147 | @end table |
| 28148 | |
| 28149 | @node close |
| 28150 | @unnumberedsubsubsec close |
| 28151 | @cindex close, file-i/o system call |
| 28152 | |
| 28153 | @table @asis |
| 28154 | @item Synopsis: |
| 28155 | @smallexample |
| 28156 | int close(int fd); |
| 28157 | @end smallexample |
| 28158 | |
| 28159 | @item Request: |
| 28160 | @samp{Fclose,@var{fd}} |
| 28161 | |
| 28162 | @item Return value: |
| 28163 | @code{close} returns zero on success, or -1 if an error occurred. |
| 28164 | |
| 28165 | @item Errors: |
| 28166 | |
| 28167 | @table @code |
| 28168 | @item EBADF |
| 28169 | @var{fd} isn't a valid open file descriptor. |
| 28170 | |
| 28171 | @item EINTR |
| 28172 | The call was interrupted by the user. |
| 28173 | @end table |
| 28174 | |
| 28175 | @end table |
| 28176 | |
| 28177 | @node read |
| 28178 | @unnumberedsubsubsec read |
| 28179 | @cindex read, file-i/o system call |
| 28180 | |
| 28181 | @table @asis |
| 28182 | @item Synopsis: |
| 28183 | @smallexample |
| 28184 | int read(int fd, void *buf, unsigned int count); |
| 28185 | @end smallexample |
| 28186 | |
| 28187 | @item Request: |
| 28188 | @samp{Fread,@var{fd},@var{bufptr},@var{count}} |
| 28189 | |
| 28190 | @item Return value: |
| 28191 | On success, the number of bytes read is returned. |
| 28192 | Zero indicates end of file. If count is zero, read |
| 28193 | returns zero as well. On error, -1 is returned. |
| 28194 | |
| 28195 | @item Errors: |
| 28196 | |
| 28197 | @table @code |
| 28198 | @item EBADF |
| 28199 | @var{fd} is not a valid file descriptor or is not open for |
| 28200 | reading. |
| 28201 | |
| 28202 | @item EFAULT |
| 28203 | @var{bufptr} is an invalid pointer value. |
| 28204 | |
| 28205 | @item EINTR |
| 28206 | The call was interrupted by the user. |
| 28207 | @end table |
| 28208 | |
| 28209 | @end table |
| 28210 | |
| 28211 | @node write |
| 28212 | @unnumberedsubsubsec write |
| 28213 | @cindex write, file-i/o system call |
| 28214 | |
| 28215 | @table @asis |
| 28216 | @item Synopsis: |
| 28217 | @smallexample |
| 28218 | int write(int fd, const void *buf, unsigned int count); |
| 28219 | @end smallexample |
| 28220 | |
| 28221 | @item Request: |
| 28222 | @samp{Fwrite,@var{fd},@var{bufptr},@var{count}} |
| 28223 | |
| 28224 | @item Return value: |
| 28225 | On success, the number of bytes written are returned. |
| 28226 | Zero indicates nothing was written. On error, -1 |
| 28227 | is returned. |
| 28228 | |
| 28229 | @item Errors: |
| 28230 | |
| 28231 | @table @code |
| 28232 | @item EBADF |
| 28233 | @var{fd} is not a valid file descriptor or is not open for |
| 28234 | writing. |
| 28235 | |
| 28236 | @item EFAULT |
| 28237 | @var{bufptr} is an invalid pointer value. |
| 28238 | |
| 28239 | @item EFBIG |
| 28240 | An attempt was made to write a file that exceeds the |
| 28241 | host-specific maximum file size allowed. |
| 28242 | |
| 28243 | @item ENOSPC |
| 28244 | No space on device to write the data. |
| 28245 | |
| 28246 | @item EINTR |
| 28247 | The call was interrupted by the user. |
| 28248 | @end table |
| 28249 | |
| 28250 | @end table |
| 28251 | |
| 28252 | @node lseek |
| 28253 | @unnumberedsubsubsec lseek |
| 28254 | @cindex lseek, file-i/o system call |
| 28255 | |
| 28256 | @table @asis |
| 28257 | @item Synopsis: |
| 28258 | @smallexample |
| 28259 | long lseek (int fd, long offset, int flag); |
| 28260 | @end smallexample |
| 28261 | |
| 28262 | @item Request: |
| 28263 | @samp{Flseek,@var{fd},@var{offset},@var{flag}} |
| 28264 | |
| 28265 | @var{flag} is one of: |
| 28266 | |
| 28267 | @table @code |
| 28268 | @item SEEK_SET |
| 28269 | The offset is set to @var{offset} bytes. |
| 28270 | |
| 28271 | @item SEEK_CUR |
| 28272 | The offset is set to its current location plus @var{offset} |
| 28273 | bytes. |
| 28274 | |
| 28275 | @item SEEK_END |
| 28276 | The offset is set to the size of the file plus @var{offset} |
| 28277 | bytes. |
| 28278 | @end table |
| 28279 | |
| 28280 | @item Return value: |
| 28281 | On success, the resulting unsigned offset in bytes from |
| 28282 | the beginning of the file is returned. Otherwise, a |
| 28283 | value of -1 is returned. |
| 28284 | |
| 28285 | @item Errors: |
| 28286 | |
| 28287 | @table @code |
| 28288 | @item EBADF |
| 28289 | @var{fd} is not a valid open file descriptor. |
| 28290 | |
| 28291 | @item ESPIPE |
| 28292 | @var{fd} is associated with the @value{GDBN} console. |
| 28293 | |
| 28294 | @item EINVAL |
| 28295 | @var{flag} is not a proper value. |
| 28296 | |
| 28297 | @item EINTR |
| 28298 | The call was interrupted by the user. |
| 28299 | @end table |
| 28300 | |
| 28301 | @end table |
| 28302 | |
| 28303 | @node rename |
| 28304 | @unnumberedsubsubsec rename |
| 28305 | @cindex rename, file-i/o system call |
| 28306 | |
| 28307 | @table @asis |
| 28308 | @item Synopsis: |
| 28309 | @smallexample |
| 28310 | int rename(const char *oldpath, const char *newpath); |
| 28311 | @end smallexample |
| 28312 | |
| 28313 | @item Request: |
| 28314 | @samp{Frename,@var{oldpathptr}/@var{len},@var{newpathptr}/@var{len}} |
| 28315 | |
| 28316 | @item Return value: |
| 28317 | On success, zero is returned. On error, -1 is returned. |
| 28318 | |
| 28319 | @item Errors: |
| 28320 | |
| 28321 | @table @code |
| 28322 | @item EISDIR |
| 28323 | @var{newpath} is an existing directory, but @var{oldpath} is not a |
| 28324 | directory. |
| 28325 | |
| 28326 | @item EEXIST |
| 28327 | @var{newpath} is a non-empty directory. |
| 28328 | |
| 28329 | @item EBUSY |
| 28330 | @var{oldpath} or @var{newpath} is a directory that is in use by some |
| 28331 | process. |
| 28332 | |
| 28333 | @item EINVAL |
| 28334 | An attempt was made to make a directory a subdirectory |
| 28335 | of itself. |
| 28336 | |
| 28337 | @item ENOTDIR |
| 28338 | A component used as a directory in @var{oldpath} or new |
| 28339 | path is not a directory. Or @var{oldpath} is a directory |
| 28340 | and @var{newpath} exists but is not a directory. |
| 28341 | |
| 28342 | @item EFAULT |
| 28343 | @var{oldpathptr} or @var{newpathptr} are invalid pointer values. |
| 28344 | |
| 28345 | @item EACCES |
| 28346 | No access to the file or the path of the file. |
| 28347 | |
| 28348 | @item ENAMETOOLONG |
| 28349 | |
| 28350 | @var{oldpath} or @var{newpath} was too long. |
| 28351 | |
| 28352 | @item ENOENT |
| 28353 | A directory component in @var{oldpath} or @var{newpath} does not exist. |
| 28354 | |
| 28355 | @item EROFS |
| 28356 | The file is on a read-only filesystem. |
| 28357 | |
| 28358 | @item ENOSPC |
| 28359 | The device containing the file has no room for the new |
| 28360 | directory entry. |
| 28361 | |
| 28362 | @item EINTR |
| 28363 | The call was interrupted by the user. |
| 28364 | @end table |
| 28365 | |
| 28366 | @end table |
| 28367 | |
| 28368 | @node unlink |
| 28369 | @unnumberedsubsubsec unlink |
| 28370 | @cindex unlink, file-i/o system call |
| 28371 | |
| 28372 | @table @asis |
| 28373 | @item Synopsis: |
| 28374 | @smallexample |
| 28375 | int unlink(const char *pathname); |
| 28376 | @end smallexample |
| 28377 | |
| 28378 | @item Request: |
| 28379 | @samp{Funlink,@var{pathnameptr}/@var{len}} |
| 28380 | |
| 28381 | @item Return value: |
| 28382 | On success, zero is returned. On error, -1 is returned. |
| 28383 | |
| 28384 | @item Errors: |
| 28385 | |
| 28386 | @table @code |
| 28387 | @item EACCES |
| 28388 | No access to the file or the path of the file. |
| 28389 | |
| 28390 | @item EPERM |
| 28391 | The system does not allow unlinking of directories. |
| 28392 | |
| 28393 | @item EBUSY |
| 28394 | The file @var{pathname} cannot be unlinked because it's |
| 28395 | being used by another process. |
| 28396 | |
| 28397 | @item EFAULT |
| 28398 | @var{pathnameptr} is an invalid pointer value. |
| 28399 | |
| 28400 | @item ENAMETOOLONG |
| 28401 | @var{pathname} was too long. |
| 28402 | |
| 28403 | @item ENOENT |
| 28404 | A directory component in @var{pathname} does not exist. |
| 28405 | |
| 28406 | @item ENOTDIR |
| 28407 | A component of the path is not a directory. |
| 28408 | |
| 28409 | @item EROFS |
| 28410 | The file is on a read-only filesystem. |
| 28411 | |
| 28412 | @item EINTR |
| 28413 | The call was interrupted by the user. |
| 28414 | @end table |
| 28415 | |
| 28416 | @end table |
| 28417 | |
| 28418 | @node stat/fstat |
| 28419 | @unnumberedsubsubsec stat/fstat |
| 28420 | @cindex fstat, file-i/o system call |
| 28421 | @cindex stat, file-i/o system call |
| 28422 | |
| 28423 | @table @asis |
| 28424 | @item Synopsis: |
| 28425 | @smallexample |
| 28426 | int stat(const char *pathname, struct stat *buf); |
| 28427 | int fstat(int fd, struct stat *buf); |
| 28428 | @end smallexample |
| 28429 | |
| 28430 | @item Request: |
| 28431 | @samp{Fstat,@var{pathnameptr}/@var{len},@var{bufptr}}@* |
| 28432 | @samp{Ffstat,@var{fd},@var{bufptr}} |
| 28433 | |
| 28434 | @item Return value: |
| 28435 | On success, zero is returned. On error, -1 is returned. |
| 28436 | |
| 28437 | @item Errors: |
| 28438 | |
| 28439 | @table @code |
| 28440 | @item EBADF |
| 28441 | @var{fd} is not a valid open file. |
| 28442 | |
| 28443 | @item ENOENT |
| 28444 | A directory component in @var{pathname} does not exist or the |
| 28445 | path is an empty string. |
| 28446 | |
| 28447 | @item ENOTDIR |
| 28448 | A component of the path is not a directory. |
| 28449 | |
| 28450 | @item EFAULT |
| 28451 | @var{pathnameptr} is an invalid pointer value. |
| 28452 | |
| 28453 | @item EACCES |
| 28454 | No access to the file or the path of the file. |
| 28455 | |
| 28456 | @item ENAMETOOLONG |
| 28457 | @var{pathname} was too long. |
| 28458 | |
| 28459 | @item EINTR |
| 28460 | The call was interrupted by the user. |
| 28461 | @end table |
| 28462 | |
| 28463 | @end table |
| 28464 | |
| 28465 | @node gettimeofday |
| 28466 | @unnumberedsubsubsec gettimeofday |
| 28467 | @cindex gettimeofday, file-i/o system call |
| 28468 | |
| 28469 | @table @asis |
| 28470 | @item Synopsis: |
| 28471 | @smallexample |
| 28472 | int gettimeofday(struct timeval *tv, void *tz); |
| 28473 | @end smallexample |
| 28474 | |
| 28475 | @item Request: |
| 28476 | @samp{Fgettimeofday,@var{tvptr},@var{tzptr}} |
| 28477 | |
| 28478 | @item Return value: |
| 28479 | On success, 0 is returned, -1 otherwise. |
| 28480 | |
| 28481 | @item Errors: |
| 28482 | |
| 28483 | @table @code |
| 28484 | @item EINVAL |
| 28485 | @var{tz} is a non-NULL pointer. |
| 28486 | |
| 28487 | @item EFAULT |
| 28488 | @var{tvptr} and/or @var{tzptr} is an invalid pointer value. |
| 28489 | @end table |
| 28490 | |
| 28491 | @end table |
| 28492 | |
| 28493 | @node isatty |
| 28494 | @unnumberedsubsubsec isatty |
| 28495 | @cindex isatty, file-i/o system call |
| 28496 | |
| 28497 | @table @asis |
| 28498 | @item Synopsis: |
| 28499 | @smallexample |
| 28500 | int isatty(int fd); |
| 28501 | @end smallexample |
| 28502 | |
| 28503 | @item Request: |
| 28504 | @samp{Fisatty,@var{fd}} |
| 28505 | |
| 28506 | @item Return value: |
| 28507 | Returns 1 if @var{fd} refers to the @value{GDBN} console, 0 otherwise. |
| 28508 | |
| 28509 | @item Errors: |
| 28510 | |
| 28511 | @table @code |
| 28512 | @item EINTR |
| 28513 | The call was interrupted by the user. |
| 28514 | @end table |
| 28515 | |
| 28516 | @end table |
| 28517 | |
| 28518 | Note that the @code{isatty} call is treated as a special case: it returns |
| 28519 | 1 to the target if the file descriptor is attached |
| 28520 | to the @value{GDBN} console, 0 otherwise. Implementing through system calls |
| 28521 | would require implementing @code{ioctl} and would be more complex than |
| 28522 | needed. |
| 28523 | |
| 28524 | |
| 28525 | @node system |
| 28526 | @unnumberedsubsubsec system |
| 28527 | @cindex system, file-i/o system call |
| 28528 | |
| 28529 | @table @asis |
| 28530 | @item Synopsis: |
| 28531 | @smallexample |
| 28532 | int system(const char *command); |
| 28533 | @end smallexample |
| 28534 | |
| 28535 | @item Request: |
| 28536 | @samp{Fsystem,@var{commandptr}/@var{len}} |
| 28537 | |
| 28538 | @item Return value: |
| 28539 | If @var{len} is zero, the return value indicates whether a shell is |
| 28540 | available. A zero return value indicates a shell is not available. |
| 28541 | For non-zero @var{len}, the value returned is -1 on error and the |
| 28542 | return status of the command otherwise. Only the exit status of the |
| 28543 | command is returned, which is extracted from the host's @code{system} |
| 28544 | return value by calling @code{WEXITSTATUS(retval)}. In case |
| 28545 | @file{/bin/sh} could not be executed, 127 is returned. |
| 28546 | |
| 28547 | @item Errors: |
| 28548 | |
| 28549 | @table @code |
| 28550 | @item EINTR |
| 28551 | The call was interrupted by the user. |
| 28552 | @end table |
| 28553 | |
| 28554 | @end table |
| 28555 | |
| 28556 | @value{GDBN} takes over the full task of calling the necessary host calls |
| 28557 | to perform the @code{system} call. The return value of @code{system} on |
| 28558 | the host is simplified before it's returned |
| 28559 | to the target. Any termination signal information from the child process |
| 28560 | is discarded, and the return value consists |
| 28561 | entirely of the exit status of the called command. |
| 28562 | |
| 28563 | Due to security concerns, the @code{system} call is by default refused |
| 28564 | by @value{GDBN}. The user has to allow this call explicitly with the |
| 28565 | @code{set remote system-call-allowed 1} command. |
| 28566 | |
| 28567 | @table @code |
| 28568 | @item set remote system-call-allowed |
| 28569 | @kindex set remote system-call-allowed |
| 28570 | Control whether to allow the @code{system} calls in the File I/O |
| 28571 | protocol for the remote target. The default is zero (disabled). |
| 28572 | |
| 28573 | @item show remote system-call-allowed |
| 28574 | @kindex show remote system-call-allowed |
| 28575 | Show whether the @code{system} calls are allowed in the File I/O |
| 28576 | protocol. |
| 28577 | @end table |
| 28578 | |
| 28579 | @node Protocol-specific Representation of Datatypes |
| 28580 | @subsection Protocol-specific Representation of Datatypes |
| 28581 | @cindex protocol-specific representation of datatypes, in file-i/o protocol |
| 28582 | |
| 28583 | @menu |
| 28584 | * Integral Datatypes:: |
| 28585 | * Pointer Values:: |
| 28586 | * Memory Transfer:: |
| 28587 | * struct stat:: |
| 28588 | * struct timeval:: |
| 28589 | @end menu |
| 28590 | |
| 28591 | @node Integral Datatypes |
| 28592 | @unnumberedsubsubsec Integral Datatypes |
| 28593 | @cindex integral datatypes, in file-i/o protocol |
| 28594 | |
| 28595 | The integral datatypes used in the system calls are @code{int}, |
| 28596 | @code{unsigned int}, @code{long}, @code{unsigned long}, |
| 28597 | @code{mode_t}, and @code{time_t}. |
| 28598 | |
| 28599 | @code{int}, @code{unsigned int}, @code{mode_t} and @code{time_t} are |
| 28600 | implemented as 32 bit values in this protocol. |
| 28601 | |
| 28602 | @code{long} and @code{unsigned long} are implemented as 64 bit types. |
| 28603 | |
| 28604 | @xref{Limits}, for corresponding MIN and MAX values (similar to those |
| 28605 | in @file{limits.h}) to allow range checking on host and target. |
| 28606 | |
| 28607 | @code{time_t} datatypes are defined as seconds since the Epoch. |
| 28608 | |
| 28609 | All integral datatypes transferred as part of a memory read or write of a |
| 28610 | structured datatype e.g.@: a @code{struct stat} have to be given in big endian |
| 28611 | byte order. |
| 28612 | |
| 28613 | @node Pointer Values |
| 28614 | @unnumberedsubsubsec Pointer Values |
| 28615 | @cindex pointer values, in file-i/o protocol |
| 28616 | |
| 28617 | Pointers to target data are transmitted as they are. An exception |
| 28618 | is made for pointers to buffers for which the length isn't |
| 28619 | transmitted as part of the function call, namely strings. Strings |
| 28620 | are transmitted as a pointer/length pair, both as hex values, e.g.@: |
| 28621 | |
| 28622 | @smallexample |
| 28623 | @code{1aaf/12} |
| 28624 | @end smallexample |
| 28625 | |
| 28626 | @noindent |
| 28627 | which is a pointer to data of length 18 bytes at position 0x1aaf. |
| 28628 | The length is defined as the full string length in bytes, including |
| 28629 | the trailing null byte. For example, the string @code{"hello world"} |
| 28630 | at address 0x123456 is transmitted as |
| 28631 | |
| 28632 | @smallexample |
| 28633 | @code{123456/d} |
| 28634 | @end smallexample |
| 28635 | |
| 28636 | @node Memory Transfer |
| 28637 | @unnumberedsubsubsec Memory Transfer |
| 28638 | @cindex memory transfer, in file-i/o protocol |
| 28639 | |
| 28640 | Structured data which is transferred using a memory read or write (for |
| 28641 | example, a @code{struct stat}) is expected to be in a protocol-specific format |
| 28642 | with all scalar multibyte datatypes being big endian. Translation to |
| 28643 | this representation needs to be done both by the target before the @code{F} |
| 28644 | packet is sent, and by @value{GDBN} before |
| 28645 | it transfers memory to the target. Transferred pointers to structured |
| 28646 | data should point to the already-coerced data at any time. |
| 28647 | |
| 28648 | |
| 28649 | @node struct stat |
| 28650 | @unnumberedsubsubsec struct stat |
| 28651 | @cindex struct stat, in file-i/o protocol |
| 28652 | |
| 28653 | The buffer of type @code{struct stat} used by the target and @value{GDBN} |
| 28654 | is defined as follows: |
| 28655 | |
| 28656 | @smallexample |
| 28657 | struct stat @{ |
| 28658 | unsigned int st_dev; /* device */ |
| 28659 | unsigned int st_ino; /* inode */ |
| 28660 | mode_t st_mode; /* protection */ |
| 28661 | unsigned int st_nlink; /* number of hard links */ |
| 28662 | unsigned int st_uid; /* user ID of owner */ |
| 28663 | unsigned int st_gid; /* group ID of owner */ |
| 28664 | unsigned int st_rdev; /* device type (if inode device) */ |
| 28665 | unsigned long st_size; /* total size, in bytes */ |
| 28666 | unsigned long st_blksize; /* blocksize for filesystem I/O */ |
| 28667 | unsigned long st_blocks; /* number of blocks allocated */ |
| 28668 | time_t st_atime; /* time of last access */ |
| 28669 | time_t st_mtime; /* time of last modification */ |
| 28670 | time_t st_ctime; /* time of last change */ |
| 28671 | @}; |
| 28672 | @end smallexample |
| 28673 | |
| 28674 | The integral datatypes conform to the definitions given in the |
| 28675 | appropriate section (see @ref{Integral Datatypes}, for details) so this |
| 28676 | structure is of size 64 bytes. |
| 28677 | |
| 28678 | The values of several fields have a restricted meaning and/or |
| 28679 | range of values. |
| 28680 | |
| 28681 | @table @code |
| 28682 | |
| 28683 | @item st_dev |
| 28684 | A value of 0 represents a file, 1 the console. |
| 28685 | |
| 28686 | @item st_ino |
| 28687 | No valid meaning for the target. Transmitted unchanged. |
| 28688 | |
| 28689 | @item st_mode |
| 28690 | Valid mode bits are described in @ref{Constants}. Any other |
| 28691 | bits have currently no meaning for the target. |
| 28692 | |
| 28693 | @item st_uid |
| 28694 | @itemx st_gid |
| 28695 | @itemx st_rdev |
| 28696 | No valid meaning for the target. Transmitted unchanged. |
| 28697 | |
| 28698 | @item st_atime |
| 28699 | @itemx st_mtime |
| 28700 | @itemx st_ctime |
| 28701 | These values have a host and file system dependent |
| 28702 | accuracy. Especially on Windows hosts, the file system may not |
| 28703 | support exact timing values. |
| 28704 | @end table |
| 28705 | |
| 28706 | The target gets a @code{struct stat} of the above representation and is |
| 28707 | responsible for coercing it to the target representation before |
| 28708 | continuing. |
| 28709 | |
| 28710 | Note that due to size differences between the host, target, and protocol |
| 28711 | representations of @code{struct stat} members, these members could eventually |
| 28712 | get truncated on the target. |
| 28713 | |
| 28714 | @node struct timeval |
| 28715 | @unnumberedsubsubsec struct timeval |
| 28716 | @cindex struct timeval, in file-i/o protocol |
| 28717 | |
| 28718 | The buffer of type @code{struct timeval} used by the File-I/O protocol |
| 28719 | is defined as follows: |
| 28720 | |
| 28721 | @smallexample |
| 28722 | struct timeval @{ |
| 28723 | time_t tv_sec; /* second */ |
| 28724 | long tv_usec; /* microsecond */ |
| 28725 | @}; |
| 28726 | @end smallexample |
| 28727 | |
| 28728 | The integral datatypes conform to the definitions given in the |
| 28729 | appropriate section (see @ref{Integral Datatypes}, for details) so this |
| 28730 | structure is of size 8 bytes. |
| 28731 | |
| 28732 | @node Constants |
| 28733 | @subsection Constants |
| 28734 | @cindex constants, in file-i/o protocol |
| 28735 | |
| 28736 | The following values are used for the constants inside of the |
| 28737 | protocol. @value{GDBN} and target are responsible for translating these |
| 28738 | values before and after the call as needed. |
| 28739 | |
| 28740 | @menu |
| 28741 | * Open Flags:: |
| 28742 | * mode_t Values:: |
| 28743 | * Errno Values:: |
| 28744 | * Lseek Flags:: |
| 28745 | * Limits:: |
| 28746 | @end menu |
| 28747 | |
| 28748 | @node Open Flags |
| 28749 | @unnumberedsubsubsec Open Flags |
| 28750 | @cindex open flags, in file-i/o protocol |
| 28751 | |
| 28752 | All values are given in hexadecimal representation. |
| 28753 | |
| 28754 | @smallexample |
| 28755 | O_RDONLY 0x0 |
| 28756 | O_WRONLY 0x1 |
| 28757 | O_RDWR 0x2 |
| 28758 | O_APPEND 0x8 |
| 28759 | O_CREAT 0x200 |
| 28760 | O_TRUNC 0x400 |
| 28761 | O_EXCL 0x800 |
| 28762 | @end smallexample |
| 28763 | |
| 28764 | @node mode_t Values |
| 28765 | @unnumberedsubsubsec mode_t Values |
| 28766 | @cindex mode_t values, in file-i/o protocol |
| 28767 | |
| 28768 | All values are given in octal representation. |
| 28769 | |
| 28770 | @smallexample |
| 28771 | S_IFREG 0100000 |
| 28772 | S_IFDIR 040000 |
| 28773 | S_IRUSR 0400 |
| 28774 | S_IWUSR 0200 |
| 28775 | S_IXUSR 0100 |
| 28776 | S_IRGRP 040 |
| 28777 | S_IWGRP 020 |
| 28778 | S_IXGRP 010 |
| 28779 | S_IROTH 04 |
| 28780 | S_IWOTH 02 |
| 28781 | S_IXOTH 01 |
| 28782 | @end smallexample |
| 28783 | |
| 28784 | @node Errno Values |
| 28785 | @unnumberedsubsubsec Errno Values |
| 28786 | @cindex errno values, in file-i/o protocol |
| 28787 | |
| 28788 | All values are given in decimal representation. |
| 28789 | |
| 28790 | @smallexample |
| 28791 | EPERM 1 |
| 28792 | ENOENT 2 |
| 28793 | EINTR 4 |
| 28794 | EBADF 9 |
| 28795 | EACCES 13 |
| 28796 | EFAULT 14 |
| 28797 | EBUSY 16 |
| 28798 | EEXIST 17 |
| 28799 | ENODEV 19 |
| 28800 | ENOTDIR 20 |
| 28801 | EISDIR 21 |
| 28802 | EINVAL 22 |
| 28803 | ENFILE 23 |
| 28804 | EMFILE 24 |
| 28805 | EFBIG 27 |
| 28806 | ENOSPC 28 |
| 28807 | ESPIPE 29 |
| 28808 | EROFS 30 |
| 28809 | ENAMETOOLONG 91 |
| 28810 | EUNKNOWN 9999 |
| 28811 | @end smallexample |
| 28812 | |
| 28813 | @code{EUNKNOWN} is used as a fallback error value if a host system returns |
| 28814 | any error value not in the list of supported error numbers. |
| 28815 | |
| 28816 | @node Lseek Flags |
| 28817 | @unnumberedsubsubsec Lseek Flags |
| 28818 | @cindex lseek flags, in file-i/o protocol |
| 28819 | |
| 28820 | @smallexample |
| 28821 | SEEK_SET 0 |
| 28822 | SEEK_CUR 1 |
| 28823 | SEEK_END 2 |
| 28824 | @end smallexample |
| 28825 | |
| 28826 | @node Limits |
| 28827 | @unnumberedsubsubsec Limits |
| 28828 | @cindex limits, in file-i/o protocol |
| 28829 | |
| 28830 | All values are given in decimal representation. |
| 28831 | |
| 28832 | @smallexample |
| 28833 | INT_MIN -2147483648 |
| 28834 | INT_MAX 2147483647 |
| 28835 | UINT_MAX 4294967295 |
| 28836 | LONG_MIN -9223372036854775808 |
| 28837 | LONG_MAX 9223372036854775807 |
| 28838 | ULONG_MAX 18446744073709551615 |
| 28839 | @end smallexample |
| 28840 | |
| 28841 | @node File-I/O Examples |
| 28842 | @subsection File-I/O Examples |
| 28843 | @cindex file-i/o examples |
| 28844 | |
| 28845 | Example sequence of a write call, file descriptor 3, buffer is at target |
| 28846 | address 0x1234, 6 bytes should be written: |
| 28847 | |
| 28848 | @smallexample |
| 28849 | <- @code{Fwrite,3,1234,6} |
| 28850 | @emph{request memory read from target} |
| 28851 | -> @code{m1234,6} |
| 28852 | <- XXXXXX |
| 28853 | @emph{return "6 bytes written"} |
| 28854 | -> @code{F6} |
| 28855 | @end smallexample |
| 28856 | |
| 28857 | Example sequence of a read call, file descriptor 3, buffer is at target |
| 28858 | address 0x1234, 6 bytes should be read: |
| 28859 | |
| 28860 | @smallexample |
| 28861 | <- @code{Fread,3,1234,6} |
| 28862 | @emph{request memory write to target} |
| 28863 | -> @code{X1234,6:XXXXXX} |
| 28864 | @emph{return "6 bytes read"} |
| 28865 | -> @code{F6} |
| 28866 | @end smallexample |
| 28867 | |
| 28868 | Example sequence of a read call, call fails on the host due to invalid |
| 28869 | file descriptor (@code{EBADF}): |
| 28870 | |
| 28871 | @smallexample |
| 28872 | <- @code{Fread,3,1234,6} |
| 28873 | -> @code{F-1,9} |
| 28874 | @end smallexample |
| 28875 | |
| 28876 | Example sequence of a read call, user presses @kbd{Ctrl-c} before syscall on |
| 28877 | host is called: |
| 28878 | |
| 28879 | @smallexample |
| 28880 | <- @code{Fread,3,1234,6} |
| 28881 | -> @code{F-1,4,C} |
| 28882 | <- @code{T02} |
| 28883 | @end smallexample |
| 28884 | |
| 28885 | Example sequence of a read call, user presses @kbd{Ctrl-c} after syscall on |
| 28886 | host is called: |
| 28887 | |
| 28888 | @smallexample |
| 28889 | <- @code{Fread,3,1234,6} |
| 28890 | -> @code{X1234,6:XXXXXX} |
| 28891 | <- @code{T02} |
| 28892 | @end smallexample |
| 28893 | |
| 28894 | @node Library List Format |
| 28895 | @section Library List Format |
| 28896 | @cindex library list format, remote protocol |
| 28897 | |
| 28898 | On some platforms, a dynamic loader (e.g.@: @file{ld.so}) runs in the |
| 28899 | same process as your application to manage libraries. In this case, |
| 28900 | @value{GDBN} can use the loader's symbol table and normal memory |
| 28901 | operations to maintain a list of shared libraries. On other |
| 28902 | platforms, the operating system manages loaded libraries. |
| 28903 | @value{GDBN} can not retrieve the list of currently loaded libraries |
| 28904 | through memory operations, so it uses the @samp{qXfer:libraries:read} |
| 28905 | packet (@pxref{qXfer library list read}) instead. The remote stub |
| 28906 | queries the target's operating system and reports which libraries |
| 28907 | are loaded. |
| 28908 | |
| 28909 | The @samp{qXfer:libraries:read} packet returns an XML document which |
| 28910 | lists loaded libraries and their offsets. Each library has an |
| 28911 | associated name and one or more segment or section base addresses, |
| 28912 | which report where the library was loaded in memory. |
| 28913 | |
| 28914 | For the common case of libraries that are fully linked binaries, the |
| 28915 | library should have a list of segments. If the target supports |
| 28916 | dynamic linking of a relocatable object file, its library XML element |
| 28917 | should instead include a list of allocated sections. The segment or |
| 28918 | section bases are start addresses, not relocation offsets; they do not |
| 28919 | depend on the library's link-time base addresses. |
| 28920 | |
| 28921 | @value{GDBN} must be linked with the Expat library to support XML |
| 28922 | library lists. @xref{Expat}. |
| 28923 | |
| 28924 | A simple memory map, with one loaded library relocated by a single |
| 28925 | offset, looks like this: |
| 28926 | |
| 28927 | @smallexample |
| 28928 | <library-list> |
| 28929 | <library name="/lib/libc.so.6"> |
| 28930 | <segment address="0x10000000"/> |
| 28931 | </library> |
| 28932 | </library-list> |
| 28933 | @end smallexample |
| 28934 | |
| 28935 | Another simple memory map, with one loaded library with three |
| 28936 | allocated sections (.text, .data, .bss), looks like this: |
| 28937 | |
| 28938 | @smallexample |
| 28939 | <library-list> |
| 28940 | <library name="sharedlib.o"> |
| 28941 | <section address="0x10000000"/> |
| 28942 | <section address="0x20000000"/> |
| 28943 | <section address="0x30000000"/> |
| 28944 | </library> |
| 28945 | </library-list> |
| 28946 | @end smallexample |
| 28947 | |
| 28948 | The format of a library list is described by this DTD: |
| 28949 | |
| 28950 | @smallexample |
| 28951 | <!-- library-list: Root element with versioning --> |
| 28952 | <!ELEMENT library-list (library)*> |
| 28953 | <!ATTLIST library-list version CDATA #FIXED "1.0"> |
| 28954 | <!ELEMENT library (segment*, section*)> |
| 28955 | <!ATTLIST library name CDATA #REQUIRED> |
| 28956 | <!ELEMENT segment EMPTY> |
| 28957 | <!ATTLIST segment address CDATA #REQUIRED> |
| 28958 | <!ELEMENT section EMPTY> |
| 28959 | <!ATTLIST section address CDATA #REQUIRED> |
| 28960 | @end smallexample |
| 28961 | |
| 28962 | In addition, segments and section descriptors cannot be mixed within a |
| 28963 | single library element, and you must supply at least one segment or |
| 28964 | section for each library. |
| 28965 | |
| 28966 | @node Memory Map Format |
| 28967 | @section Memory Map Format |
| 28968 | @cindex memory map format |
| 28969 | |
| 28970 | To be able to write into flash memory, @value{GDBN} needs to obtain a |
| 28971 | memory map from the target. This section describes the format of the |
| 28972 | memory map. |
| 28973 | |
| 28974 | The memory map is obtained using the @samp{qXfer:memory-map:read} |
| 28975 | (@pxref{qXfer memory map read}) packet and is an XML document that |
| 28976 | lists memory regions. |
| 28977 | |
| 28978 | @value{GDBN} must be linked with the Expat library to support XML |
| 28979 | memory maps. @xref{Expat}. |
| 28980 | |
| 28981 | The top-level structure of the document is shown below: |
| 28982 | |
| 28983 | @smallexample |
| 28984 | <?xml version="1.0"?> |
| 28985 | <!DOCTYPE memory-map |
| 28986 | PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN" |
| 28987 | "http://sourceware.org/gdb/gdb-memory-map.dtd"> |
| 28988 | <memory-map> |
| 28989 | region... |
| 28990 | </memory-map> |
| 28991 | @end smallexample |
| 28992 | |
| 28993 | Each region can be either: |
| 28994 | |
| 28995 | @itemize |
| 28996 | |
| 28997 | @item |
| 28998 | A region of RAM starting at @var{addr} and extending for @var{length} |
| 28999 | bytes from there: |
| 29000 | |
| 29001 | @smallexample |
| 29002 | <memory type="ram" start="@var{addr}" length="@var{length}"/> |
| 29003 | @end smallexample |
| 29004 | |
| 29005 | |
| 29006 | @item |
| 29007 | A region of read-only memory: |
| 29008 | |
| 29009 | @smallexample |
| 29010 | <memory type="rom" start="@var{addr}" length="@var{length}"/> |
| 29011 | @end smallexample |
| 29012 | |
| 29013 | |
| 29014 | @item |
| 29015 | A region of flash memory, with erasure blocks @var{blocksize} |
| 29016 | bytes in length: |
| 29017 | |
| 29018 | @smallexample |
| 29019 | <memory type="flash" start="@var{addr}" length="@var{length}"> |
| 29020 | <property name="blocksize">@var{blocksize}</property> |
| 29021 | </memory> |
| 29022 | @end smallexample |
| 29023 | |
| 29024 | @end itemize |
| 29025 | |
| 29026 | Regions must not overlap. @value{GDBN} assumes that areas of memory not covered |
| 29027 | by the memory map are RAM, and uses the ordinary @samp{M} and @samp{X} |
| 29028 | packets to write to addresses in such ranges. |
| 29029 | |
| 29030 | The formal DTD for memory map format is given below: |
| 29031 | |
| 29032 | @smallexample |
| 29033 | <!-- ................................................... --> |
| 29034 | <!-- Memory Map XML DTD ................................ --> |
| 29035 | <!-- File: memory-map.dtd .............................. --> |
| 29036 | <!-- .................................... .............. --> |
| 29037 | <!-- memory-map.dtd --> |
| 29038 | <!-- memory-map: Root element with versioning --> |
| 29039 | <!ELEMENT memory-map (memory | property)> |
| 29040 | <!ATTLIST memory-map version CDATA #FIXED "1.0.0"> |
| 29041 | <!ELEMENT memory (property)> |
| 29042 | <!-- memory: Specifies a memory region, |
| 29043 | and its type, or device. --> |
| 29044 | <!ATTLIST memory type CDATA #REQUIRED |
| 29045 | start CDATA #REQUIRED |
| 29046 | length CDATA #REQUIRED |
| 29047 | device CDATA #IMPLIED> |
| 29048 | <!-- property: Generic attribute tag --> |
| 29049 | <!ELEMENT property (#PCDATA | property)*> |
| 29050 | <!ATTLIST property name CDATA #REQUIRED> |
| 29051 | @end smallexample |
| 29052 | |
| 29053 | @include agentexpr.texi |
| 29054 | |
| 29055 | @node Target Descriptions |
| 29056 | @appendix Target Descriptions |
| 29057 | @cindex target descriptions |
| 29058 | |
| 29059 | @strong{Warning:} target descriptions are still under active development, |
| 29060 | and the contents and format may change between @value{GDBN} releases. |
| 29061 | The format is expected to stabilize in the future. |
| 29062 | |
| 29063 | One of the challenges of using @value{GDBN} to debug embedded systems |
| 29064 | is that there are so many minor variants of each processor |
| 29065 | architecture in use. It is common practice for vendors to start with |
| 29066 | a standard processor core --- ARM, PowerPC, or MIPS, for example --- |
| 29067 | and then make changes to adapt it to a particular market niche. Some |
| 29068 | architectures have hundreds of variants, available from dozens of |
| 29069 | vendors. This leads to a number of problems: |
| 29070 | |
| 29071 | @itemize @bullet |
| 29072 | @item |
| 29073 | With so many different customized processors, it is difficult for |
| 29074 | the @value{GDBN} maintainers to keep up with the changes. |
| 29075 | @item |
| 29076 | Since individual variants may have short lifetimes or limited |
| 29077 | audiences, it may not be worthwhile to carry information about every |
| 29078 | variant in the @value{GDBN} source tree. |
| 29079 | @item |
| 29080 | When @value{GDBN} does support the architecture of the embedded system |
| 29081 | at hand, the task of finding the correct architecture name to give the |
| 29082 | @command{set architecture} command can be error-prone. |
| 29083 | @end itemize |
| 29084 | |
| 29085 | To address these problems, the @value{GDBN} remote protocol allows a |
| 29086 | target system to not only identify itself to @value{GDBN}, but to |
| 29087 | actually describe its own features. This lets @value{GDBN} support |
| 29088 | processor variants it has never seen before --- to the extent that the |
| 29089 | descriptions are accurate, and that @value{GDBN} understands them. |
| 29090 | |
| 29091 | @value{GDBN} must be linked with the Expat library to support XML |
| 29092 | target descriptions. @xref{Expat}. |
| 29093 | |
| 29094 | @menu |
| 29095 | * Retrieving Descriptions:: How descriptions are fetched from a target. |
| 29096 | * Target Description Format:: The contents of a target description. |
| 29097 | * Predefined Target Types:: Standard types available for target |
| 29098 | descriptions. |
| 29099 | * Standard Target Features:: Features @value{GDBN} knows about. |
| 29100 | @end menu |
| 29101 | |
| 29102 | @node Retrieving Descriptions |
| 29103 | @section Retrieving Descriptions |
| 29104 | |
| 29105 | Target descriptions can be read from the target automatically, or |
| 29106 | specified by the user manually. The default behavior is to read the |
| 29107 | description from the target. @value{GDBN} retrieves it via the remote |
| 29108 | protocol using @samp{qXfer} requests (@pxref{General Query Packets, |
| 29109 | qXfer}). The @var{annex} in the @samp{qXfer} packet will be |
| 29110 | @samp{target.xml}. The contents of the @samp{target.xml} annex are an |
| 29111 | XML document, of the form described in @ref{Target Description |
| 29112 | Format}. |
| 29113 | |
| 29114 | Alternatively, you can specify a file to read for the target description. |
| 29115 | If a file is set, the target will not be queried. The commands to |
| 29116 | specify a file are: |
| 29117 | |
| 29118 | @table @code |
| 29119 | @cindex set tdesc filename |
| 29120 | @item set tdesc filename @var{path} |
| 29121 | Read the target description from @var{path}. |
| 29122 | |
| 29123 | @cindex unset tdesc filename |
| 29124 | @item unset tdesc filename |
| 29125 | Do not read the XML target description from a file. @value{GDBN} |
| 29126 | will use the description supplied by the current target. |
| 29127 | |
| 29128 | @cindex show tdesc filename |
| 29129 | @item show tdesc filename |
| 29130 | Show the filename to read for a target description, if any. |
| 29131 | @end table |
| 29132 | |
| 29133 | |
| 29134 | @node Target Description Format |
| 29135 | @section Target Description Format |
| 29136 | @cindex target descriptions, XML format |
| 29137 | |
| 29138 | A target description annex is an @uref{http://www.w3.org/XML/, XML} |
| 29139 | document which complies with the Document Type Definition provided in |
| 29140 | the @value{GDBN} sources in @file{gdb/features/gdb-target.dtd}. This |
| 29141 | means you can use generally available tools like @command{xmllint} to |
| 29142 | check that your feature descriptions are well-formed and valid. |
| 29143 | However, to help people unfamiliar with XML write descriptions for |
| 29144 | their targets, we also describe the grammar here. |
| 29145 | |
| 29146 | Target descriptions can identify the architecture of the remote target |
| 29147 | and (for some architectures) provide information about custom register |
| 29148 | sets. @value{GDBN} can use this information to autoconfigure for your |
| 29149 | target, or to warn you if you connect to an unsupported target. |
| 29150 | |
| 29151 | Here is a simple target description: |
| 29152 | |
| 29153 | @smallexample |
| 29154 | <target version="1.0"> |
| 29155 | <architecture>i386:x86-64</architecture> |
| 29156 | </target> |
| 29157 | @end smallexample |
| 29158 | |
| 29159 | @noindent |
| 29160 | This minimal description only says that the target uses |
| 29161 | the x86-64 architecture. |
| 29162 | |
| 29163 | A target description has the following overall form, with [ ] marking |
| 29164 | optional elements and @dots{} marking repeatable elements. The elements |
| 29165 | are explained further below. |
| 29166 | |
| 29167 | @smallexample |
| 29168 | <?xml version="1.0"?> |
| 29169 | <!DOCTYPE target SYSTEM "gdb-target.dtd"> |
| 29170 | <target version="1.0"> |
| 29171 | @r{[}@var{architecture}@r{]} |
| 29172 | @r{[}@var{feature}@dots{}@r{]} |
| 29173 | </target> |
| 29174 | @end smallexample |
| 29175 | |
| 29176 | @noindent |
| 29177 | The description is generally insensitive to whitespace and line |
| 29178 | breaks, under the usual common-sense rules. The XML version |
| 29179 | declaration and document type declaration can generally be omitted |
| 29180 | (@value{GDBN} does not require them), but specifying them may be |
| 29181 | useful for XML validation tools. The @samp{version} attribute for |
| 29182 | @samp{<target>} may also be omitted, but we recommend |
| 29183 | including it; if future versions of @value{GDBN} use an incompatible |
| 29184 | revision of @file{gdb-target.dtd}, they will detect and report |
| 29185 | the version mismatch. |
| 29186 | |
| 29187 | @subsection Inclusion |
| 29188 | @cindex target descriptions, inclusion |
| 29189 | @cindex XInclude |
| 29190 | @ifnotinfo |
| 29191 | @cindex <xi:include> |
| 29192 | @end ifnotinfo |
| 29193 | |
| 29194 | It can sometimes be valuable to split a target description up into |
| 29195 | several different annexes, either for organizational purposes, or to |
| 29196 | share files between different possible target descriptions. You can |
| 29197 | divide a description into multiple files by replacing any element of |
| 29198 | the target description with an inclusion directive of the form: |
| 29199 | |
| 29200 | @smallexample |
| 29201 | <xi:include href="@var{document}"/> |
| 29202 | @end smallexample |
| 29203 | |
| 29204 | @noindent |
| 29205 | When @value{GDBN} encounters an element of this form, it will retrieve |
| 29206 | the named XML @var{document}, and replace the inclusion directive with |
| 29207 | the contents of that document. If the current description was read |
| 29208 | using @samp{qXfer}, then so will be the included document; |
| 29209 | @var{document} will be interpreted as the name of an annex. If the |
| 29210 | current description was read from a file, @value{GDBN} will look for |
| 29211 | @var{document} as a file in the same directory where it found the |
| 29212 | original description. |
| 29213 | |
| 29214 | @subsection Architecture |
| 29215 | @cindex <architecture> |
| 29216 | |
| 29217 | An @samp{<architecture>} element has this form: |
| 29218 | |
| 29219 | @smallexample |
| 29220 | <architecture>@var{arch}</architecture> |
| 29221 | @end smallexample |
| 29222 | |
| 29223 | @var{arch} is an architecture name from the same selection |
| 29224 | accepted by @code{set architecture} (@pxref{Targets, ,Specifying a |
| 29225 | Debugging Target}). |
| 29226 | |
| 29227 | @subsection Features |
| 29228 | @cindex <feature> |
| 29229 | |
| 29230 | Each @samp{<feature>} describes some logical portion of the target |
| 29231 | system. Features are currently used to describe available CPU |
| 29232 | registers and the types of their contents. A @samp{<feature>} element |
| 29233 | has this form: |
| 29234 | |
| 29235 | @smallexample |
| 29236 | <feature name="@var{name}"> |
| 29237 | @r{[}@var{type}@dots{}@r{]} |
| 29238 | @var{reg}@dots{} |
| 29239 | </feature> |
| 29240 | @end smallexample |
| 29241 | |
| 29242 | @noindent |
| 29243 | Each feature's name should be unique within the description. The name |
| 29244 | of a feature does not matter unless @value{GDBN} has some special |
| 29245 | knowledge of the contents of that feature; if it does, the feature |
| 29246 | should have its standard name. @xref{Standard Target Features}. |
| 29247 | |
| 29248 | @subsection Types |
| 29249 | |
| 29250 | Any register's value is a collection of bits which @value{GDBN} must |
| 29251 | interpret. The default interpretation is a two's complement integer, |
| 29252 | but other types can be requested by name in the register description. |
| 29253 | Some predefined types are provided by @value{GDBN} (@pxref{Predefined |
| 29254 | Target Types}), and the description can define additional composite types. |
| 29255 | |
| 29256 | Each type element must have an @samp{id} attribute, which gives |
| 29257 | a unique (within the containing @samp{<feature>}) name to the type. |
| 29258 | Types must be defined before they are used. |
| 29259 | |
| 29260 | @cindex <vector> |
| 29261 | Some targets offer vector registers, which can be treated as arrays |
| 29262 | of scalar elements. These types are written as @samp{<vector>} elements, |
| 29263 | specifying the array element type, @var{type}, and the number of elements, |
| 29264 | @var{count}: |
| 29265 | |
| 29266 | @smallexample |
| 29267 | <vector id="@var{id}" type="@var{type}" count="@var{count}"/> |
| 29268 | @end smallexample |
| 29269 | |
| 29270 | @cindex <union> |
| 29271 | If a register's value is usefully viewed in multiple ways, define it |
| 29272 | with a union type containing the useful representations. The |
| 29273 | @samp{<union>} element contains one or more @samp{<field>} elements, |
| 29274 | each of which has a @var{name} and a @var{type}: |
| 29275 | |
| 29276 | @smallexample |
| 29277 | <union id="@var{id}"> |
| 29278 | <field name="@var{name}" type="@var{type}"/> |
| 29279 | @dots{} |
| 29280 | </union> |
| 29281 | @end smallexample |
| 29282 | |
| 29283 | @subsection Registers |
| 29284 | @cindex <reg> |
| 29285 | |
| 29286 | Each register is represented as an element with this form: |
| 29287 | |
| 29288 | @smallexample |
| 29289 | <reg name="@var{name}" |
| 29290 | bitsize="@var{size}" |
| 29291 | @r{[}regnum="@var{num}"@r{]} |
| 29292 | @r{[}save-restore="@var{save-restore}"@r{]} |
| 29293 | @r{[}type="@var{type}"@r{]} |
| 29294 | @r{[}group="@var{group}"@r{]}/> |
| 29295 | @end smallexample |
| 29296 | |
| 29297 | @noindent |
| 29298 | The components are as follows: |
| 29299 | |
| 29300 | @table @var |
| 29301 | |
| 29302 | @item name |
| 29303 | The register's name; it must be unique within the target description. |
| 29304 | |
| 29305 | @item bitsize |
| 29306 | The register's size, in bits. |
| 29307 | |
| 29308 | @item regnum |
| 29309 | The register's number. If omitted, a register's number is one greater |
| 29310 | than that of the previous register (either in the current feature or in |
| 29311 | a preceeding feature); the first register in the target description |
| 29312 | defaults to zero. This register number is used to read or write |
| 29313 | the register; e.g.@: it is used in the remote @code{p} and @code{P} |
| 29314 | packets, and registers appear in the @code{g} and @code{G} packets |
| 29315 | in order of increasing register number. |
| 29316 | |
| 29317 | @item save-restore |
| 29318 | Whether the register should be preserved across inferior function |
| 29319 | calls; this must be either @code{yes} or @code{no}. The default is |
| 29320 | @code{yes}, which is appropriate for most registers except for |
| 29321 | some system control registers; this is not related to the target's |
| 29322 | ABI. |
| 29323 | |
| 29324 | @item type |
| 29325 | The type of the register. @var{type} may be a predefined type, a type |
| 29326 | defined in the current feature, or one of the special types @code{int} |
| 29327 | and @code{float}. @code{int} is an integer type of the correct size |
| 29328 | for @var{bitsize}, and @code{float} is a floating point type (in the |
| 29329 | architecture's normal floating point format) of the correct size for |
| 29330 | @var{bitsize}. The default is @code{int}. |
| 29331 | |
| 29332 | @item group |
| 29333 | The register group to which this register belongs. @var{group} must |
| 29334 | be either @code{general}, @code{float}, or @code{vector}. If no |
| 29335 | @var{group} is specified, @value{GDBN} will not display the register |
| 29336 | in @code{info registers}. |
| 29337 | |
| 29338 | @end table |
| 29339 | |
| 29340 | @node Predefined Target Types |
| 29341 | @section Predefined Target Types |
| 29342 | @cindex target descriptions, predefined types |
| 29343 | |
| 29344 | Type definitions in the self-description can build up composite types |
| 29345 | from basic building blocks, but can not define fundamental types. Instead, |
| 29346 | standard identifiers are provided by @value{GDBN} for the fundamental |
| 29347 | types. The currently supported types are: |
| 29348 | |
| 29349 | @table @code |
| 29350 | |
| 29351 | @item int8 |
| 29352 | @itemx int16 |
| 29353 | @itemx int32 |
| 29354 | @itemx int64 |
| 29355 | @itemx int128 |
| 29356 | Signed integer types holding the specified number of bits. |
| 29357 | |
| 29358 | @item uint8 |
| 29359 | @itemx uint16 |
| 29360 | @itemx uint32 |
| 29361 | @itemx uint64 |
| 29362 | @itemx uint128 |
| 29363 | Unsigned integer types holding the specified number of bits. |
| 29364 | |
| 29365 | @item code_ptr |
| 29366 | @itemx data_ptr |
| 29367 | Pointers to unspecified code and data. The program counter and |
| 29368 | any dedicated return address register may be marked as code |
| 29369 | pointers; printing a code pointer converts it into a symbolic |
| 29370 | address. The stack pointer and any dedicated address registers |
| 29371 | may be marked as data pointers. |
| 29372 | |
| 29373 | @item ieee_single |
| 29374 | Single precision IEEE floating point. |
| 29375 | |
| 29376 | @item ieee_double |
| 29377 | Double precision IEEE floating point. |
| 29378 | |
| 29379 | @item arm_fpa_ext |
| 29380 | The 12-byte extended precision format used by ARM FPA registers. |
| 29381 | |
| 29382 | @end table |
| 29383 | |
| 29384 | @node Standard Target Features |
| 29385 | @section Standard Target Features |
| 29386 | @cindex target descriptions, standard features |
| 29387 | |
| 29388 | A target description must contain either no registers or all the |
| 29389 | target's registers. If the description contains no registers, then |
| 29390 | @value{GDBN} will assume a default register layout, selected based on |
| 29391 | the architecture. If the description contains any registers, the |
| 29392 | default layout will not be used; the standard registers must be |
| 29393 | described in the target description, in such a way that @value{GDBN} |
| 29394 | can recognize them. |
| 29395 | |
| 29396 | This is accomplished by giving specific names to feature elements |
| 29397 | which contain standard registers. @value{GDBN} will look for features |
| 29398 | with those names and verify that they contain the expected registers; |
| 29399 | if any known feature is missing required registers, or if any required |
| 29400 | feature is missing, @value{GDBN} will reject the target |
| 29401 | description. You can add additional registers to any of the |
| 29402 | standard features --- @value{GDBN} will display them just as if |
| 29403 | they were added to an unrecognized feature. |
| 29404 | |
| 29405 | This section lists the known features and their expected contents. |
| 29406 | Sample XML documents for these features are included in the |
| 29407 | @value{GDBN} source tree, in the directory @file{gdb/features}. |
| 29408 | |
| 29409 | Names recognized by @value{GDBN} should include the name of the |
| 29410 | company or organization which selected the name, and the overall |
| 29411 | architecture to which the feature applies; so e.g.@: the feature |
| 29412 | containing ARM core registers is named @samp{org.gnu.gdb.arm.core}. |
| 29413 | |
| 29414 | The names of registers are not case sensitive for the purpose |
| 29415 | of recognizing standard features, but @value{GDBN} will only display |
| 29416 | registers using the capitalization used in the description. |
| 29417 | |
| 29418 | @menu |
| 29419 | * ARM Features:: |
| 29420 | * MIPS Features:: |
| 29421 | * M68K Features:: |
| 29422 | * PowerPC Features:: |
| 29423 | @end menu |
| 29424 | |
| 29425 | |
| 29426 | @node ARM Features |
| 29427 | @subsection ARM Features |
| 29428 | @cindex target descriptions, ARM features |
| 29429 | |
| 29430 | The @samp{org.gnu.gdb.arm.core} feature is required for ARM targets. |
| 29431 | It should contain registers @samp{r0} through @samp{r13}, @samp{sp}, |
| 29432 | @samp{lr}, @samp{pc}, and @samp{cpsr}. |
| 29433 | |
| 29434 | The @samp{org.gnu.gdb.arm.fpa} feature is optional. If present, it |
| 29435 | should contain registers @samp{f0} through @samp{f7} and @samp{fps}. |
| 29436 | |
| 29437 | The @samp{org.gnu.gdb.xscale.iwmmxt} feature is optional. If present, |
| 29438 | it should contain at least registers @samp{wR0} through @samp{wR15} and |
| 29439 | @samp{wCGR0} through @samp{wCGR3}. The @samp{wCID}, @samp{wCon}, |
| 29440 | @samp{wCSSF}, and @samp{wCASF} registers are optional. |
| 29441 | |
| 29442 | @node MIPS Features |
| 29443 | @subsection MIPS Features |
| 29444 | @cindex target descriptions, MIPS features |
| 29445 | |
| 29446 | The @samp{org.gnu.gdb.mips.cpu} feature is required for MIPS targets. |
| 29447 | It should contain registers @samp{r0} through @samp{r31}, @samp{lo}, |
| 29448 | @samp{hi}, and @samp{pc}. They may be 32-bit or 64-bit depending |
| 29449 | on the target. |
| 29450 | |
| 29451 | The @samp{org.gnu.gdb.mips.cp0} feature is also required. It should |
| 29452 | contain at least the @samp{status}, @samp{badvaddr}, and @samp{cause} |
| 29453 | registers. They may be 32-bit or 64-bit depending on the target. |
| 29454 | |
| 29455 | The @samp{org.gnu.gdb.mips.fpu} feature is currently required, though |
| 29456 | it may be optional in a future version of @value{GDBN}. It should |
| 29457 | contain registers @samp{f0} through @samp{f31}, @samp{fcsr}, and |
| 29458 | @samp{fir}. They may be 32-bit or 64-bit depending on the target. |
| 29459 | |
| 29460 | The @samp{org.gnu.gdb.mips.linux} feature is optional. It should |
| 29461 | contain a single register, @samp{restart}, which is used by the |
| 29462 | Linux kernel to control restartable syscalls. |
| 29463 | |
| 29464 | @node M68K Features |
| 29465 | @subsection M68K Features |
| 29466 | @cindex target descriptions, M68K features |
| 29467 | |
| 29468 | @table @code |
| 29469 | @item @samp{org.gnu.gdb.m68k.core} |
| 29470 | @itemx @samp{org.gnu.gdb.coldfire.core} |
| 29471 | @itemx @samp{org.gnu.gdb.fido.core} |
| 29472 | One of those features must be always present. |
| 29473 | The feature that is present determines which flavor of m68k is |
| 29474 | used. The feature that is present should contain registers |
| 29475 | @samp{d0} through @samp{d7}, @samp{a0} through @samp{a5}, @samp{fp}, |
| 29476 | @samp{sp}, @samp{ps} and @samp{pc}. |
| 29477 | |
| 29478 | @item @samp{org.gnu.gdb.coldfire.fp} |
| 29479 | This feature is optional. If present, it should contain registers |
| 29480 | @samp{fp0} through @samp{fp7}, @samp{fpcontrol}, @samp{fpstatus} and |
| 29481 | @samp{fpiaddr}. |
| 29482 | @end table |
| 29483 | |
| 29484 | @node PowerPC Features |
| 29485 | @subsection PowerPC Features |
| 29486 | @cindex target descriptions, PowerPC features |
| 29487 | |
| 29488 | The @samp{org.gnu.gdb.power.core} feature is required for PowerPC |
| 29489 | targets. It should contain registers @samp{r0} through @samp{r31}, |
| 29490 | @samp{pc}, @samp{msr}, @samp{cr}, @samp{lr}, @samp{ctr}, and |
| 29491 | @samp{xer}. They may be 32-bit or 64-bit depending on the target. |
| 29492 | |
| 29493 | The @samp{org.gnu.gdb.power.fpu} feature is optional. It should |
| 29494 | contain registers @samp{f0} through @samp{f31} and @samp{fpscr}. |
| 29495 | |
| 29496 | The @samp{org.gnu.gdb.power.altivec} feature is optional. It should |
| 29497 | contain registers @samp{vr0} through @samp{vr31}, @samp{vscr}, |
| 29498 | and @samp{vrsave}. |
| 29499 | |
| 29500 | The @samp{org.gnu.gdb.power.vsx} feature is optional. It should |
| 29501 | contain registers @samp{vs0h} through @samp{vs31h}. @value{GDBN} |
| 29502 | will combine these registers with the floating point registers |
| 29503 | (@samp{f0} through @samp{f31}) and the altivec registers (@samp{vr0} |
| 29504 | through @samp{vr31}) to present the 128-bit wide registers @samp{vs0} |
| 29505 | through @samp{vs63}, the set of vector registers for POWER7. |
| 29506 | |
| 29507 | The @samp{org.gnu.gdb.power.spe} feature is optional. It should |
| 29508 | contain registers @samp{ev0h} through @samp{ev31h}, @samp{acc}, and |
| 29509 | @samp{spefscr}. SPE targets should provide 32-bit registers in |
| 29510 | @samp{org.gnu.gdb.power.core} and provide the upper halves in |
| 29511 | @samp{ev0h} through @samp{ev31h}. @value{GDBN} will combine |
| 29512 | these to present registers @samp{ev0} through @samp{ev31} to the |
| 29513 | user. |
| 29514 | |
| 29515 | @node Operating System Information |
| 29516 | @appendix Operating System Information |
| 29517 | @cindex operating system information |
| 29518 | |
| 29519 | @menu |
| 29520 | * Process list:: |
| 29521 | @end menu |
| 29522 | |
| 29523 | Users of @value{GDBN} often wish to obtain information about the state of |
| 29524 | the operating system running on the target---for example the list of |
| 29525 | processes, or the list of open files. This section describes the |
| 29526 | mechanism that makes it possible. This mechanism is similar to the |
| 29527 | target features mechanism (@pxref{Target Descriptions}), but focuses |
| 29528 | on a different aspect of target. |
| 29529 | |
| 29530 | Operating system information is retrived from the target via the |
| 29531 | remote protocol, using @samp{qXfer} requests (@pxref{qXfer osdata |
| 29532 | read}). The object name in the request should be @samp{osdata}, and |
| 29533 | the @var{annex} identifies the data to be fetched. |
| 29534 | |
| 29535 | @node Process list |
| 29536 | @appendixsection Process list |
| 29537 | @cindex operating system information, process list |
| 29538 | |
| 29539 | When requesting the process list, the @var{annex} field in the |
| 29540 | @samp{qXfer} request should be @samp{processes}. The returned data is |
| 29541 | an XML document. The formal syntax of this document is defined in |
| 29542 | @file{gdb/features/osdata.dtd}. |
| 29543 | |
| 29544 | An example document is: |
| 29545 | |
| 29546 | @smallexample |
| 29547 | <?xml version="1.0"?> |
| 29548 | <!DOCTYPE target SYSTEM "osdata.dtd"> |
| 29549 | <osdata type="processes"> |
| 29550 | <item> |
| 29551 | <column name="pid">1</column> |
| 29552 | <column name="user">root</column> |
| 29553 | <column name="command">/sbin/init</column> |
| 29554 | </item> |
| 29555 | </osdata> |
| 29556 | @end smallexample |
| 29557 | |
| 29558 | Each item should include a column whose name is @samp{pid}. The value |
| 29559 | of that column should identify the process on the target. The |
| 29560 | @samp{user} and @samp{command} columns are optional, and will be |
| 29561 | displayed by @value{GDBN}. Target may provide additional columns, |
| 29562 | which @value{GDBN} currently ignores. |
| 29563 | |
| 29564 | @include gpl.texi |
| 29565 | |
| 29566 | @raisesections |
| 29567 | @include fdl.texi |
| 29568 | @lowersections |
| 29569 | |
| 29570 | @node Index |
| 29571 | @unnumbered Index |
| 29572 | |
| 29573 | @printindex cp |
| 29574 | |
| 29575 | @tex |
| 29576 | % I think something like @colophon should be in texinfo. In the |
| 29577 | % meantime: |
| 29578 | \long\def\colophon{\hbox to0pt{}\vfill |
| 29579 | \centerline{The body of this manual is set in} |
| 29580 | \centerline{\fontname\tenrm,} |
| 29581 | \centerline{with headings in {\bf\fontname\tenbf}} |
| 29582 | \centerline{and examples in {\tt\fontname\tentt}.} |
| 29583 | \centerline{{\it\fontname\tenit\/},} |
| 29584 | \centerline{{\bf\fontname\tenbf}, and} |
| 29585 | \centerline{{\sl\fontname\tensl\/}} |
| 29586 | \centerline{are used for emphasis.}\vfill} |
| 29587 | \page\colophon |
| 29588 | % Blame: doc@cygnus.com, 1991. |
| 29589 | @end tex |
| 29590 | |
| 29591 | @bye |