| 1 | \input texinfo @c -*-texinfo-*- |
| 2 | @c Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, |
| 3 | @c 1999, 2000, 2001, 2002, 2003 |
| 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 | @set EDITION Ninth |
| 32 | |
| 33 | @c !!set GDB manual's revision date |
| 34 | @set DATE June 2002 |
| 35 | |
| 36 | @c !!set GDB edit command default editor |
| 37 | @set EDITOR /bin/ex |
| 38 | |
| 39 | @c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER. |
| 40 | |
| 41 | @c This is a dir.info fragment to support semi-automated addition of |
| 42 | @c manuals to an info tree. |
| 43 | @dircategory Programming & development tools. |
| 44 | @direntry |
| 45 | * Gdb: (gdb). The @sc{gnu} debugger. |
| 46 | @end direntry |
| 47 | |
| 48 | @ifinfo |
| 49 | This file documents the @sc{gnu} debugger @value{GDBN}. |
| 50 | |
| 51 | |
| 52 | This is the @value{EDITION} Edition, @value{DATE}, |
| 53 | of @cite{Debugging with @value{GDBN}: the @sc{gnu} Source-Level Debugger} |
| 54 | for @value{GDBN} Version @value{GDBVN}. |
| 55 | |
| 56 | Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,@* |
| 57 | 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
| 58 | |
| 59 | Permission is granted to copy, distribute and/or modify this document |
| 60 | under the terms of the GNU Free Documentation License, Version 1.1 or |
| 61 | any later version published by the Free Software Foundation; with the |
| 62 | Invariant Sections being ``Free Software'' and ``Free Software Needs |
| 63 | Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' |
| 64 | and with the Back-Cover Texts as in (a) below. |
| 65 | |
| 66 | (a) The Free Software Foundation's Back-Cover Text is: ``You have |
| 67 | freedom to copy and modify this GNU Manual, like GNU software. Copies |
| 68 | published by the Free Software Foundation raise funds for GNU |
| 69 | development.'' |
| 70 | @end ifinfo |
| 71 | |
| 72 | @titlepage |
| 73 | @title Debugging with @value{GDBN} |
| 74 | @subtitle The @sc{gnu} Source-Level Debugger |
| 75 | @sp 1 |
| 76 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
| 77 | @subtitle @value{DATE} |
| 78 | @author Richard Stallman, Roland Pesch, Stan Shebs, et al. |
| 79 | @page |
| 80 | @tex |
| 81 | {\parskip=0pt |
| 82 | \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@gnu.org.)\par |
| 83 | \hfill {\it Debugging with @value{GDBN}}\par |
| 84 | \hfill \TeX{}info \texinfoversion\par |
| 85 | } |
| 86 | @end tex |
| 87 | |
| 88 | @vskip 0pt plus 1filll |
| 89 | Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, |
| 90 | 1996, 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc. |
| 91 | @sp 2 |
| 92 | Published by the Free Software Foundation @* |
| 93 | 59 Temple Place - Suite 330, @* |
| 94 | Boston, MA 02111-1307 USA @* |
| 95 | ISBN 1-882114-77-9 @* |
| 96 | |
| 97 | Permission is granted to copy, distribute and/or modify this document |
| 98 | under the terms of the GNU Free Documentation License, Version 1.1 or |
| 99 | any later version published by the Free Software Foundation; with the |
| 100 | Invariant Sections being ``Free Software'' and ``Free Software Needs |
| 101 | Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' |
| 102 | and with the Back-Cover Texts as in (a) below. |
| 103 | |
| 104 | (a) The Free Software Foundation's Back-Cover Text is: ``You have |
| 105 | freedom to copy and modify this GNU Manual, like GNU software. Copies |
| 106 | published by the Free Software Foundation raise funds for GNU |
| 107 | development.'' |
| 108 | @end titlepage |
| 109 | @page |
| 110 | |
| 111 | @ifnottex |
| 112 | @node Top, Summary, (dir), (dir) |
| 113 | |
| 114 | @top Debugging with @value{GDBN} |
| 115 | |
| 116 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. |
| 117 | |
| 118 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version |
| 119 | @value{GDBVN}. |
| 120 | |
| 121 | Copyright (C) 1988-2003 Free Software Foundation, Inc. |
| 122 | |
| 123 | @menu |
| 124 | * Summary:: Summary of @value{GDBN} |
| 125 | * Sample Session:: A sample @value{GDBN} session |
| 126 | |
| 127 | * Invocation:: Getting in and out of @value{GDBN} |
| 128 | * Commands:: @value{GDBN} commands |
| 129 | * Running:: Running programs under @value{GDBN} |
| 130 | * Stopping:: Stopping and continuing |
| 131 | * Stack:: Examining the stack |
| 132 | * Source:: Examining source files |
| 133 | * Data:: Examining data |
| 134 | * Macros:: Preprocessor Macros |
| 135 | * Tracepoints:: Debugging remote targets non-intrusively |
| 136 | * Overlays:: Debugging programs that use overlays |
| 137 | |
| 138 | * Languages:: Using @value{GDBN} with different languages |
| 139 | |
| 140 | * Symbols:: Examining the symbol table |
| 141 | * Altering:: Altering execution |
| 142 | * GDB Files:: @value{GDBN} files |
| 143 | * Targets:: Specifying a debugging target |
| 144 | * Remote Debugging:: Debugging remote programs |
| 145 | * Configurations:: Configuration-specific information |
| 146 | * Controlling GDB:: Controlling @value{GDBN} |
| 147 | * Sequences:: Canned sequences of commands |
| 148 | * TUI:: @value{GDBN} Text User Interface |
| 149 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
| 150 | * Annotations:: @value{GDBN}'s annotation interface. |
| 151 | * GDB/MI:: @value{GDBN}'s Machine Interface. |
| 152 | |
| 153 | * GDB Bugs:: Reporting bugs in @value{GDBN} |
| 154 | * Formatting Documentation:: How to format and print @value{GDBN} documentation |
| 155 | |
| 156 | * Command Line Editing:: Command Line Editing |
| 157 | * Using History Interactively:: Using History Interactively |
| 158 | * Installing GDB:: Installing GDB |
| 159 | * Maintenance Commands:: Maintenance Commands |
| 160 | * Remote Protocol:: GDB Remote Serial Protocol |
| 161 | * Copying:: GNU General Public License says |
| 162 | how you can copy and share GDB |
| 163 | * GNU Free Documentation License:: The license for this documentation |
| 164 | * Index:: Index |
| 165 | @end menu |
| 166 | |
| 167 | @end ifnottex |
| 168 | |
| 169 | @contents |
| 170 | |
| 171 | @node Summary |
| 172 | @unnumbered Summary of @value{GDBN} |
| 173 | |
| 174 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is |
| 175 | going on ``inside'' another program while it executes---or what another |
| 176 | program was doing at the moment it crashed. |
| 177 | |
| 178 | @value{GDBN} can do four main kinds of things (plus other things in support of |
| 179 | these) to help you catch bugs in the act: |
| 180 | |
| 181 | @itemize @bullet |
| 182 | @item |
| 183 | Start your program, specifying anything that might affect its behavior. |
| 184 | |
| 185 | @item |
| 186 | Make your program stop on specified conditions. |
| 187 | |
| 188 | @item |
| 189 | Examine what has happened, when your program has stopped. |
| 190 | |
| 191 | @item |
| 192 | Change things in your program, so you can experiment with correcting the |
| 193 | effects of one bug and go on to learn about another. |
| 194 | @end itemize |
| 195 | |
| 196 | You can use @value{GDBN} to debug programs written in C and C++. |
| 197 | For more information, see @ref{Support,,Supported languages}. |
| 198 | For more information, see @ref{C,,C and C++}. |
| 199 | |
| 200 | @cindex Modula-2 |
| 201 | Support for Modula-2 is partial. For information on Modula-2, see |
| 202 | @ref{Modula-2,,Modula-2}. |
| 203 | |
| 204 | @cindex Pascal |
| 205 | Debugging Pascal programs which use sets, subranges, file variables, or |
| 206 | nested functions does not currently work. @value{GDBN} does not support |
| 207 | entering expressions, printing values, or similar features using Pascal |
| 208 | syntax. |
| 209 | |
| 210 | @cindex Fortran |
| 211 | @value{GDBN} can be used to debug programs written in Fortran, although |
| 212 | it may be necessary to refer to some variables with a trailing |
| 213 | underscore. |
| 214 | |
| 215 | @menu |
| 216 | * Free Software:: Freely redistributable software |
| 217 | * Contributors:: Contributors to GDB |
| 218 | @end menu |
| 219 | |
| 220 | @node Free Software |
| 221 | @unnumberedsec Free software |
| 222 | |
| 223 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} |
| 224 | General Public License |
| 225 | (GPL). The GPL gives you the freedom to copy or adapt a licensed |
| 226 | program---but every person getting a copy also gets with it the |
| 227 | freedom to modify that copy (which means that they must get access to |
| 228 | the source code), and the freedom to distribute further copies. |
| 229 | Typical software companies use copyrights to limit your freedoms; the |
| 230 | Free Software Foundation uses the GPL to preserve these freedoms. |
| 231 | |
| 232 | Fundamentally, the General Public License is a license which says that |
| 233 | you have these freedoms and that you cannot take these freedoms away |
| 234 | from anyone else. |
| 235 | |
| 236 | @unnumberedsec Free Software Needs Free Documentation |
| 237 | |
| 238 | The biggest deficiency in the free software community today is not in |
| 239 | the software---it is the lack of good free documentation that we can |
| 240 | include with the free software. Many of our most important |
| 241 | programs do not come with free reference manuals and free introductory |
| 242 | texts. Documentation is an essential part of any software package; |
| 243 | when an important free software package does not come with a free |
| 244 | manual and a free tutorial, that is a major gap. We have many such |
| 245 | gaps today. |
| 246 | |
| 247 | Consider Perl, for instance. The tutorial manuals that people |
| 248 | normally use are non-free. How did this come about? Because the |
| 249 | authors of those manuals published them with restrictive terms---no |
| 250 | copying, no modification, source files not available---which exclude |
| 251 | them from the free software world. |
| 252 | |
| 253 | That wasn't the first time this sort of thing happened, and it was far |
| 254 | from the last. Many times we have heard a GNU user eagerly describe a |
| 255 | manual that he is writing, his intended contribution to the community, |
| 256 | only to learn that he had ruined everything by signing a publication |
| 257 | contract to make it non-free. |
| 258 | |
| 259 | Free documentation, like free software, is a matter of freedom, not |
| 260 | price. The problem with the non-free manual is not that publishers |
| 261 | charge a price for printed copies---that in itself is fine. (The Free |
| 262 | Software Foundation sells printed copies of manuals, too.) The |
| 263 | problem is the restrictions on the use of the manual. Free manuals |
| 264 | are available in source code form, and give you permission to copy and |
| 265 | modify. Non-free manuals do not allow this. |
| 266 | |
| 267 | The criteria of freedom for a free manual are roughly the same as for |
| 268 | free software. Redistribution (including the normal kinds of |
| 269 | commercial redistribution) must be permitted, so that the manual can |
| 270 | accompany every copy of the program, both on-line and on paper. |
| 271 | |
| 272 | Permission for modification of the technical content is crucial too. |
| 273 | When people modify the software, adding or changing features, if they |
| 274 | are conscientious they will change the manual too---so they can |
| 275 | provide accurate and clear documentation for the modified program. A |
| 276 | manual that leaves you no choice but to write a new manual to document |
| 277 | a changed version of the program is not really available to our |
| 278 | community. |
| 279 | |
| 280 | Some kinds of limits on the way modification is handled are |
| 281 | acceptable. For example, requirements to preserve the original |
| 282 | author's copyright notice, the distribution terms, or the list of |
| 283 | authors, are ok. It is also no problem to require modified versions |
| 284 | to include notice that they were modified. Even entire sections that |
| 285 | may not be deleted or changed are acceptable, as long as they deal |
| 286 | with nontechnical topics (like this one). These kinds of restrictions |
| 287 | are acceptable because they don't obstruct the community's normal use |
| 288 | of the manual. |
| 289 | |
| 290 | However, it must be possible to modify all the @emph{technical} |
| 291 | content of the manual, and then distribute the result in all the usual |
| 292 | media, through all the usual channels. Otherwise, the restrictions |
| 293 | obstruct the use of the manual, it is not free, and we need another |
| 294 | manual to replace it. |
| 295 | |
| 296 | Please spread the word about this issue. Our community continues to |
| 297 | lose manuals to proprietary publishing. If we spread the word that |
| 298 | free software needs free reference manuals and free tutorials, perhaps |
| 299 | the next person who wants to contribute by writing documentation will |
| 300 | realize, before it is too late, that only free manuals contribute to |
| 301 | the free software community. |
| 302 | |
| 303 | If you are writing documentation, please insist on publishing it under |
| 304 | the GNU Free Documentation License or another free documentation |
| 305 | license. Remember that this decision requires your approval---you |
| 306 | don't have to let the publisher decide. Some commercial publishers |
| 307 | will use a free license if you insist, but they will not propose the |
| 308 | option; it is up to you to raise the issue and say firmly that this is |
| 309 | what you want. If the publisher you are dealing with refuses, please |
| 310 | try other publishers. If you're not sure whether a proposed license |
| 311 | is free, write to @email{licensing@@gnu.org}. |
| 312 | |
| 313 | You can encourage commercial publishers to sell more free, copylefted |
| 314 | manuals and tutorials by buying them, and particularly by buying |
| 315 | copies from the publishers that paid for their writing or for major |
| 316 | improvements. Meanwhile, try to avoid buying non-free documentation |
| 317 | at all. Check the distribution terms of a manual before you buy it, |
| 318 | and insist that whoever seeks your business must respect your freedom. |
| 319 | Check the history of the book, and try to reward the publishers that |
| 320 | have paid or pay the authors to work on it. |
| 321 | |
| 322 | The Free Software Foundation maintains a list of free documentation |
| 323 | published by other publishers, at |
| 324 | @url{http://www.fsf.org/doc/other-free-books.html}. |
| 325 | |
| 326 | @node Contributors |
| 327 | @unnumberedsec Contributors to @value{GDBN} |
| 328 | |
| 329 | Richard Stallman was the original author of @value{GDBN}, and of many |
| 330 | other @sc{gnu} programs. Many others have contributed to its |
| 331 | development. This section attempts to credit major contributors. One |
| 332 | of the virtues of free software is that everyone is free to contribute |
| 333 | to it; with regret, we cannot actually acknowledge everyone here. The |
| 334 | file @file{ChangeLog} in the @value{GDBN} distribution approximates a |
| 335 | blow-by-blow account. |
| 336 | |
| 337 | Changes much prior to version 2.0 are lost in the mists of time. |
| 338 | |
| 339 | @quotation |
| 340 | @emph{Plea:} Additions to this section are particularly welcome. If you |
| 341 | or your friends (or enemies, to be evenhanded) have been unfairly |
| 342 | omitted from this list, we would like to add your names! |
| 343 | @end quotation |
| 344 | |
| 345 | So that they may not regard their many labors as thankless, we |
| 346 | particularly thank those who shepherded @value{GDBN} through major |
| 347 | releases: |
| 348 | Andrew Cagney (releases 5.3, 5.2, 5.1 and 5.0); |
| 349 | Jim Blandy (release 4.18); |
| 350 | Jason Molenda (release 4.17); |
| 351 | Stan Shebs (release 4.14); |
| 352 | Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9); |
| 353 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4); |
| 354 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); |
| 355 | Jim Kingdon (releases 3.5, 3.4, and 3.3); |
| 356 | and Randy Smith (releases 3.2, 3.1, and 3.0). |
| 357 | |
| 358 | Richard Stallman, assisted at various times by Peter TerMaat, Chris |
| 359 | Hanson, and Richard Mlynarik, handled releases through 2.8. |
| 360 | |
| 361 | Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support |
| 362 | in @value{GDBN}, with significant additional contributions from Per |
| 363 | Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++} |
| 364 | demangler. Early work on C@t{++} was by Peter TerMaat (who also did |
| 365 | much general update work leading to release 3.0). |
| 366 | |
| 367 | @value{GDBN} uses the BFD subroutine library to examine multiple |
| 368 | object-file formats; BFD was a joint project of David V. |
| 369 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. |
| 370 | |
| 371 | David Johnson wrote the original COFF support; Pace Willison did |
| 372 | the original support for encapsulated COFF. |
| 373 | |
| 374 | Brent Benson of Harris Computer Systems contributed DWARF2 support. |
| 375 | |
| 376 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. |
| 377 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS |
| 378 | support. |
| 379 | Jean-Daniel Fekete contributed Sun 386i support. |
| 380 | Chris Hanson improved the HP9000 support. |
| 381 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. |
| 382 | David Johnson contributed Encore Umax support. |
| 383 | Jyrki Kuoppala contributed Altos 3068 support. |
| 384 | Jeff Law contributed HP PA and SOM support. |
| 385 | Keith Packard contributed NS32K support. |
| 386 | Doug Rabson contributed Acorn Risc Machine support. |
| 387 | Bob Rusk contributed Harris Nighthawk CX-UX support. |
| 388 | Chris Smith contributed Convex support (and Fortran debugging). |
| 389 | Jonathan Stone contributed Pyramid support. |
| 390 | Michael Tiemann contributed SPARC support. |
| 391 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. |
| 392 | Pace Willison contributed Intel 386 support. |
| 393 | Jay Vosburgh contributed Symmetry support. |
| 394 | Marko Mlinar contributed OpenRISC 1000 support. |
| 395 | |
| 396 | Andreas Schwab contributed M68K @sc{gnu}/Linux support. |
| 397 | |
| 398 | Rich Schaefer and Peter Schauer helped with support of SunOS shared |
| 399 | libraries. |
| 400 | |
| 401 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree |
| 402 | about several machine instruction sets. |
| 403 | |
| 404 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop |
| 405 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM |
| 406 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, |
| 407 | and RDI targets, respectively. |
| 408 | |
| 409 | Brian Fox is the author of the readline libraries providing |
| 410 | command-line editing and command history. |
| 411 | |
| 412 | Andrew Beers of SUNY Buffalo wrote the language-switching code, the |
| 413 | Modula-2 support, and contributed the Languages chapter of this manual. |
| 414 | |
| 415 | Fred Fish wrote most of the support for Unix System Vr4. |
| 416 | He also enhanced the command-completion support to cover C@t{++} overloaded |
| 417 | symbols. |
| 418 | |
| 419 | Hitachi America, Ltd. sponsored the support for H8/300, H8/500, and |
| 420 | Super-H processors. |
| 421 | |
| 422 | NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors. |
| 423 | |
| 424 | Mitsubishi sponsored the support for D10V, D30V, and M32R/D processors. |
| 425 | |
| 426 | Toshiba sponsored the support for the TX39 Mips processor. |
| 427 | |
| 428 | Matsushita sponsored the support for the MN10200 and MN10300 processors. |
| 429 | |
| 430 | Fujitsu sponsored the support for SPARClite and FR30 processors. |
| 431 | |
| 432 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware |
| 433 | watchpoints. |
| 434 | |
| 435 | Michael Snyder added support for tracepoints. |
| 436 | |
| 437 | Stu Grossman wrote gdbserver. |
| 438 | |
| 439 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made |
| 440 | nearly innumerable bug fixes and cleanups throughout @value{GDBN}. |
| 441 | |
| 442 | The following people at the Hewlett-Packard Company contributed |
| 443 | support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0 |
| 444 | (narrow mode), HP's implementation of kernel threads, HP's aC@t{++} |
| 445 | compiler, and the terminal user interface: Ben Krepp, Richard Title, |
| 446 | John Bishop, Susan Macchia, Kathy Mann, Satish Pai, India Paul, Steve |
| 447 | Rehrauer, and Elena Zannoni. Kim Haase provided HP-specific |
| 448 | information in this manual. |
| 449 | |
| 450 | DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project. |
| 451 | Robert Hoehne made significant contributions to the DJGPP port. |
| 452 | |
| 453 | Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its |
| 454 | development since 1991. Cygnus engineers who have worked on @value{GDBN} |
| 455 | fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin |
| 456 | Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim |
| 457 | Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler, |
| 458 | Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek |
| 459 | Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In |
| 460 | addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton, |
| 461 | JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug |
| 462 | Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff |
| 463 | Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner, |
| 464 | Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin |
| 465 | Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela |
| 466 | Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David |
| 467 | Zuhn have made contributions both large and small. |
| 468 | |
| 469 | Jim Blandy added support for preprocessor macros, while working for Red |
| 470 | Hat. |
| 471 | |
| 472 | @node Sample Session |
| 473 | @chapter A Sample @value{GDBN} Session |
| 474 | |
| 475 | You can use this manual at your leisure to read all about @value{GDBN}. |
| 476 | However, a handful of commands are enough to get started using the |
| 477 | debugger. This chapter illustrates those commands. |
| 478 | |
| 479 | @iftex |
| 480 | In this sample session, we emphasize user input like this: @b{input}, |
| 481 | to make it easier to pick out from the surrounding output. |
| 482 | @end iftex |
| 483 | |
| 484 | @c FIXME: this example may not be appropriate for some configs, where |
| 485 | @c FIXME...primary interest is in remote use. |
| 486 | |
| 487 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro |
| 488 | processor) exhibits the following bug: sometimes, when we change its |
| 489 | quote strings from the default, the commands used to capture one macro |
| 490 | definition within another stop working. In the following short @code{m4} |
| 491 | session, we define a macro @code{foo} which expands to @code{0000}; we |
| 492 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the |
| 493 | same thing. However, when we change the open quote string to |
| 494 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same |
| 495 | procedure fails to define a new synonym @code{baz}: |
| 496 | |
| 497 | @smallexample |
| 498 | $ @b{cd gnu/m4} |
| 499 | $ @b{./m4} |
| 500 | @b{define(foo,0000)} |
| 501 | |
| 502 | @b{foo} |
| 503 | 0000 |
| 504 | @b{define(bar,defn(`foo'))} |
| 505 | |
| 506 | @b{bar} |
| 507 | 0000 |
| 508 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
| 509 | |
| 510 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
| 511 | @b{baz} |
| 512 | @b{C-d} |
| 513 | m4: End of input: 0: fatal error: EOF in string |
| 514 | @end smallexample |
| 515 | |
| 516 | @noindent |
| 517 | Let us use @value{GDBN} to try to see what is going on. |
| 518 | |
| 519 | @smallexample |
| 520 | $ @b{@value{GDBP} m4} |
| 521 | @c FIXME: this falsifies the exact text played out, to permit smallbook |
| 522 | @c FIXME... format to come out better. |
| 523 | @value{GDBN} is free software and you are welcome to distribute copies |
| 524 | of it under certain conditions; type "show copying" to see |
| 525 | the conditions. |
| 526 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
| 527 | for details. |
| 528 | |
| 529 | @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc... |
| 530 | (@value{GDBP}) |
| 531 | @end smallexample |
| 532 | |
| 533 | @noindent |
| 534 | @value{GDBN} reads only enough symbol data to know where to find the |
| 535 | rest when needed; as a result, the first prompt comes up very quickly. |
| 536 | We now tell @value{GDBN} to use a narrower display width than usual, so |
| 537 | that examples fit in this manual. |
| 538 | |
| 539 | @smallexample |
| 540 | (@value{GDBP}) @b{set width 70} |
| 541 | @end smallexample |
| 542 | |
| 543 | @noindent |
| 544 | We need to see how the @code{m4} built-in @code{changequote} works. |
| 545 | Having looked at the source, we know the relevant subroutine is |
| 546 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} |
| 547 | @code{break} command. |
| 548 | |
| 549 | @smallexample |
| 550 | (@value{GDBP}) @b{break m4_changequote} |
| 551 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. |
| 552 | @end smallexample |
| 553 | |
| 554 | @noindent |
| 555 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} |
| 556 | control; as long as control does not reach the @code{m4_changequote} |
| 557 | subroutine, the program runs as usual: |
| 558 | |
| 559 | @smallexample |
| 560 | (@value{GDBP}) @b{run} |
| 561 | Starting program: /work/Editorial/gdb/gnu/m4/m4 |
| 562 | @b{define(foo,0000)} |
| 563 | |
| 564 | @b{foo} |
| 565 | 0000 |
| 566 | @end smallexample |
| 567 | |
| 568 | @noindent |
| 569 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} |
| 570 | suspends execution of @code{m4}, displaying information about the |
| 571 | context where it stops. |
| 572 | |
| 573 | @smallexample |
| 574 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
| 575 | |
| 576 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) |
| 577 | at builtin.c:879 |
| 578 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) |
| 579 | @end smallexample |
| 580 | |
| 581 | @noindent |
| 582 | Now we use the command @code{n} (@code{next}) to advance execution to |
| 583 | the next line of the current function. |
| 584 | |
| 585 | @smallexample |
| 586 | (@value{GDBP}) @b{n} |
| 587 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ |
| 588 | : nil, |
| 589 | @end smallexample |
| 590 | |
| 591 | @noindent |
| 592 | @code{set_quotes} looks like a promising subroutine. We can go into it |
| 593 | by using the command @code{s} (@code{step}) instead of @code{next}. |
| 594 | @code{step} goes to the next line to be executed in @emph{any} |
| 595 | subroutine, so it steps into @code{set_quotes}. |
| 596 | |
| 597 | @smallexample |
| 598 | (@value{GDBP}) @b{s} |
| 599 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
| 600 | at input.c:530 |
| 601 | 530 if (lquote != def_lquote) |
| 602 | @end smallexample |
| 603 | |
| 604 | @noindent |
| 605 | The display that shows the subroutine where @code{m4} is now |
| 606 | suspended (and its arguments) is called a stack frame display. It |
| 607 | shows a summary of the stack. We can use the @code{backtrace} |
| 608 | command (which can also be spelled @code{bt}), to see where we are |
| 609 | in the stack as a whole: the @code{backtrace} command displays a |
| 610 | stack frame for each active subroutine. |
| 611 | |
| 612 | @smallexample |
| 613 | (@value{GDBP}) @b{bt} |
| 614 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
| 615 | at input.c:530 |
| 616 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) |
| 617 | at builtin.c:882 |
| 618 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 |
| 619 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) |
| 620 | at macro.c:71 |
| 621 | #4 0x79dc in expand_input () at macro.c:40 |
| 622 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 |
| 623 | @end smallexample |
| 624 | |
| 625 | @noindent |
| 626 | We step through a few more lines to see what happens. The first two |
| 627 | times, we can use @samp{s}; the next two times we use @code{n} to avoid |
| 628 | falling into the @code{xstrdup} subroutine. |
| 629 | |
| 630 | @smallexample |
| 631 | (@value{GDBP}) @b{s} |
| 632 | 0x3b5c 532 if (rquote != def_rquote) |
| 633 | (@value{GDBP}) @b{s} |
| 634 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ |
| 635 | def_lquote : xstrdup(lq); |
| 636 | (@value{GDBP}) @b{n} |
| 637 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ |
| 638 | : xstrdup(rq); |
| 639 | (@value{GDBP}) @b{n} |
| 640 | 538 len_lquote = strlen(rquote); |
| 641 | @end smallexample |
| 642 | |
| 643 | @noindent |
| 644 | The last line displayed looks a little odd; we can examine the variables |
| 645 | @code{lquote} and @code{rquote} to see if they are in fact the new left |
| 646 | and right quotes we specified. We use the command @code{p} |
| 647 | (@code{print}) to see their values. |
| 648 | |
| 649 | @smallexample |
| 650 | (@value{GDBP}) @b{p lquote} |
| 651 | $1 = 0x35d40 "<QUOTE>" |
| 652 | (@value{GDBP}) @b{p rquote} |
| 653 | $2 = 0x35d50 "<UNQUOTE>" |
| 654 | @end smallexample |
| 655 | |
| 656 | @noindent |
| 657 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. |
| 658 | To look at some context, we can display ten lines of source |
| 659 | surrounding the current line with the @code{l} (@code{list}) command. |
| 660 | |
| 661 | @smallexample |
| 662 | (@value{GDBP}) @b{l} |
| 663 | 533 xfree(rquote); |
| 664 | 534 |
| 665 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ |
| 666 | : xstrdup (lq); |
| 667 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ |
| 668 | : xstrdup (rq); |
| 669 | 537 |
| 670 | 538 len_lquote = strlen(rquote); |
| 671 | 539 len_rquote = strlen(lquote); |
| 672 | 540 @} |
| 673 | 541 |
| 674 | 542 void |
| 675 | @end smallexample |
| 676 | |
| 677 | @noindent |
| 678 | Let us step past the two lines that set @code{len_lquote} and |
| 679 | @code{len_rquote}, and then examine the values of those variables. |
| 680 | |
| 681 | @smallexample |
| 682 | (@value{GDBP}) @b{n} |
| 683 | 539 len_rquote = strlen(lquote); |
| 684 | (@value{GDBP}) @b{n} |
| 685 | 540 @} |
| 686 | (@value{GDBP}) @b{p len_lquote} |
| 687 | $3 = 9 |
| 688 | (@value{GDBP}) @b{p len_rquote} |
| 689 | $4 = 7 |
| 690 | @end smallexample |
| 691 | |
| 692 | @noindent |
| 693 | That certainly looks wrong, assuming @code{len_lquote} and |
| 694 | @code{len_rquote} are meant to be the lengths of @code{lquote} and |
| 695 | @code{rquote} respectively. We can set them to better values using |
| 696 | the @code{p} command, since it can print the value of |
| 697 | any expression---and that expression can include subroutine calls and |
| 698 | assignments. |
| 699 | |
| 700 | @smallexample |
| 701 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} |
| 702 | $5 = 7 |
| 703 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} |
| 704 | $6 = 9 |
| 705 | @end smallexample |
| 706 | |
| 707 | @noindent |
| 708 | Is that enough to fix the problem of using the new quotes with the |
| 709 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue |
| 710 | executing with the @code{c} (@code{continue}) command, and then try the |
| 711 | example that caused trouble initially: |
| 712 | |
| 713 | @smallexample |
| 714 | (@value{GDBP}) @b{c} |
| 715 | Continuing. |
| 716 | |
| 717 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
| 718 | |
| 719 | baz |
| 720 | 0000 |
| 721 | @end smallexample |
| 722 | |
| 723 | @noindent |
| 724 | Success! The new quotes now work just as well as the default ones. The |
| 725 | problem seems to have been just the two typos defining the wrong |
| 726 | lengths. We allow @code{m4} exit by giving it an EOF as input: |
| 727 | |
| 728 | @smallexample |
| 729 | @b{C-d} |
| 730 | Program exited normally. |
| 731 | @end smallexample |
| 732 | |
| 733 | @noindent |
| 734 | The message @samp{Program exited normally.} is from @value{GDBN}; it |
| 735 | indicates @code{m4} has finished executing. We can end our @value{GDBN} |
| 736 | session with the @value{GDBN} @code{quit} command. |
| 737 | |
| 738 | @smallexample |
| 739 | (@value{GDBP}) @b{quit} |
| 740 | @end smallexample |
| 741 | |
| 742 | @node Invocation |
| 743 | @chapter Getting In and Out of @value{GDBN} |
| 744 | |
| 745 | This chapter discusses how to start @value{GDBN}, and how to get out of it. |
| 746 | The essentials are: |
| 747 | @itemize @bullet |
| 748 | @item |
| 749 | type @samp{@value{GDBP}} to start @value{GDBN}. |
| 750 | @item |
| 751 | type @kbd{quit} or @kbd{C-d} to exit. |
| 752 | @end itemize |
| 753 | |
| 754 | @menu |
| 755 | * Invoking GDB:: How to start @value{GDBN} |
| 756 | * Quitting GDB:: How to quit @value{GDBN} |
| 757 | * Shell Commands:: How to use shell commands inside @value{GDBN} |
| 758 | @end menu |
| 759 | |
| 760 | @node Invoking GDB |
| 761 | @section Invoking @value{GDBN} |
| 762 | |
| 763 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
| 764 | @value{GDBN} reads commands from the terminal until you tell it to exit. |
| 765 | |
| 766 | You can also run @code{@value{GDBP}} with a variety of arguments and options, |
| 767 | to specify more of your debugging environment at the outset. |
| 768 | |
| 769 | The command-line options described here are designed |
| 770 | to cover a variety of situations; in some environments, some of these |
| 771 | options may effectively be unavailable. |
| 772 | |
| 773 | The most usual way to start @value{GDBN} is with one argument, |
| 774 | specifying an executable program: |
| 775 | |
| 776 | @smallexample |
| 777 | @value{GDBP} @var{program} |
| 778 | @end smallexample |
| 779 | |
| 780 | @noindent |
| 781 | You can also start with both an executable program and a core file |
| 782 | specified: |
| 783 | |
| 784 | @smallexample |
| 785 | @value{GDBP} @var{program} @var{core} |
| 786 | @end smallexample |
| 787 | |
| 788 | You can, instead, specify a process ID as a second argument, if you want |
| 789 | to debug a running process: |
| 790 | |
| 791 | @smallexample |
| 792 | @value{GDBP} @var{program} 1234 |
| 793 | @end smallexample |
| 794 | |
| 795 | @noindent |
| 796 | would attach @value{GDBN} to process @code{1234} (unless you also have a file |
| 797 | named @file{1234}; @value{GDBN} does check for a core file first). |
| 798 | |
| 799 | Taking advantage of the second command-line argument requires a fairly |
| 800 | complete operating system; when you use @value{GDBN} as a remote |
| 801 | debugger attached to a bare board, there may not be any notion of |
| 802 | ``process'', and there is often no way to get a core dump. @value{GDBN} |
| 803 | will warn you if it is unable to attach or to read core dumps. |
| 804 | |
| 805 | You can optionally have @code{@value{GDBP}} pass any arguments after the |
| 806 | executable file to the inferior using @code{--args}. This option stops |
| 807 | option processing. |
| 808 | @smallexample |
| 809 | gdb --args gcc -O2 -c foo.c |
| 810 | @end smallexample |
| 811 | This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set |
| 812 | @code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}. |
| 813 | |
| 814 | You can run @code{@value{GDBP}} without printing the front material, which describes |
| 815 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: |
| 816 | |
| 817 | @smallexample |
| 818 | @value{GDBP} -silent |
| 819 | @end smallexample |
| 820 | |
| 821 | @noindent |
| 822 | You can further control how @value{GDBN} starts up by using command-line |
| 823 | options. @value{GDBN} itself can remind you of the options available. |
| 824 | |
| 825 | @noindent |
| 826 | Type |
| 827 | |
| 828 | @smallexample |
| 829 | @value{GDBP} -help |
| 830 | @end smallexample |
| 831 | |
| 832 | @noindent |
| 833 | to display all available options and briefly describe their use |
| 834 | (@samp{@value{GDBP} -h} is a shorter equivalent). |
| 835 | |
| 836 | All options and command line arguments you give are processed |
| 837 | in sequential order. The order makes a difference when the |
| 838 | @samp{-x} option is used. |
| 839 | |
| 840 | |
| 841 | @menu |
| 842 | * File Options:: Choosing files |
| 843 | * Mode Options:: Choosing modes |
| 844 | @end menu |
| 845 | |
| 846 | @node File Options |
| 847 | @subsection Choosing files |
| 848 | |
| 849 | When @value{GDBN} starts, it reads any arguments other than options as |
| 850 | specifying an executable file and core file (or process ID). This is |
| 851 | the same as if the arguments were specified by the @samp{-se} and |
| 852 | @samp{-c} (or @samp{-p} options respectively. (@value{GDBN} reads the |
| 853 | first argument that does not have an associated option flag as |
| 854 | equivalent to the @samp{-se} option followed by that argument; and the |
| 855 | second argument that does not have an associated option flag, if any, as |
| 856 | equivalent to the @samp{-c}/@samp{-p} option followed by that argument.) |
| 857 | If the second argument begins with a decimal digit, @value{GDBN} will |
| 858 | first attempt to attach to it as a process, and if that fails, attempt |
| 859 | to open it as a corefile. If you have a corefile whose name begins with |
| 860 | a digit, you can prevent @value{GDBN} from treating it as a pid by |
| 861 | prefixing it with @file{./}, eg. @file{./12345}. |
| 862 | |
| 863 | If @value{GDBN} has not been configured to included core file support, |
| 864 | such as for most embedded targets, then it will complain about a second |
| 865 | argument and ignore it. |
| 866 | |
| 867 | Many options have both long and short forms; both are shown in the |
| 868 | following list. @value{GDBN} also recognizes the long forms if you truncate |
| 869 | them, so long as enough of the option is present to be unambiguous. |
| 870 | (If you prefer, you can flag option arguments with @samp{--} rather |
| 871 | than @samp{-}, though we illustrate the more usual convention.) |
| 872 | |
| 873 | @c NOTE: the @cindex entries here use double dashes ON PURPOSE. This |
| 874 | @c way, both those who look for -foo and --foo in the index, will find |
| 875 | @c it. |
| 876 | |
| 877 | @table @code |
| 878 | @item -symbols @var{file} |
| 879 | @itemx -s @var{file} |
| 880 | @cindex @code{--symbols} |
| 881 | @cindex @code{-s} |
| 882 | Read symbol table from file @var{file}. |
| 883 | |
| 884 | @item -exec @var{file} |
| 885 | @itemx -e @var{file} |
| 886 | @cindex @code{--exec} |
| 887 | @cindex @code{-e} |
| 888 | Use file @var{file} as the executable file to execute when appropriate, |
| 889 | and for examining pure data in conjunction with a core dump. |
| 890 | |
| 891 | @item -se @var{file} |
| 892 | @cindex @code{--se} |
| 893 | Read symbol table from file @var{file} and use it as the executable |
| 894 | file. |
| 895 | |
| 896 | @item -core @var{file} |
| 897 | @itemx -c @var{file} |
| 898 | @cindex @code{--core} |
| 899 | @cindex @code{-c} |
| 900 | Use file @var{file} as a core dump to examine. |
| 901 | |
| 902 | @item -c @var{number} |
| 903 | @item -pid @var{number} |
| 904 | @itemx -p @var{number} |
| 905 | @cindex @code{--pid} |
| 906 | @cindex @code{-p} |
| 907 | Connect to process ID @var{number}, as with the @code{attach} command. |
| 908 | If there is no such process, @value{GDBN} will attempt to open a core |
| 909 | file named @var{number}. |
| 910 | |
| 911 | @item -command @var{file} |
| 912 | @itemx -x @var{file} |
| 913 | @cindex @code{--command} |
| 914 | @cindex @code{-x} |
| 915 | Execute @value{GDBN} commands from file @var{file}. @xref{Command |
| 916 | Files,, Command files}. |
| 917 | |
| 918 | @item -directory @var{directory} |
| 919 | @itemx -d @var{directory} |
| 920 | @cindex @code{--directory} |
| 921 | @cindex @code{-d} |
| 922 | Add @var{directory} to the path to search for source files. |
| 923 | |
| 924 | @item -m |
| 925 | @itemx -mapped |
| 926 | @cindex @code{--mapped} |
| 927 | @cindex @code{-m} |
| 928 | @emph{Warning: this option depends on operating system facilities that are not |
| 929 | supported on all systems.}@* |
| 930 | If memory-mapped files are available on your system through the @code{mmap} |
| 931 | system call, you can use this option |
| 932 | to have @value{GDBN} write the symbols from your |
| 933 | program into a reusable file in the current directory. If the program you are debugging is |
| 934 | called @file{/tmp/fred}, the mapped symbol file is @file{/tmp/fred.syms}. |
| 935 | Future @value{GDBN} debugging sessions notice the presence of this file, |
| 936 | and can quickly map in symbol information from it, rather than reading |
| 937 | the symbol table from the executable program. |
| 938 | |
| 939 | The @file{.syms} file is specific to the host machine where @value{GDBN} |
| 940 | is run. It holds an exact image of the internal @value{GDBN} symbol |
| 941 | table. It cannot be shared across multiple host platforms. |
| 942 | |
| 943 | @item -r |
| 944 | @itemx -readnow |
| 945 | @cindex @code{--readnow} |
| 946 | @cindex @code{-r} |
| 947 | Read each symbol file's entire symbol table immediately, rather than |
| 948 | the default, which is to read it incrementally as it is needed. |
| 949 | This makes startup slower, but makes future operations faster. |
| 950 | |
| 951 | @end table |
| 952 | |
| 953 | You typically combine the @code{-mapped} and @code{-readnow} options in |
| 954 | order to build a @file{.syms} file that contains complete symbol |
| 955 | information. (@xref{Files,,Commands to specify files}, for information |
| 956 | on @file{.syms} files.) A simple @value{GDBN} invocation to do nothing |
| 957 | but build a @file{.syms} file for future use is: |
| 958 | |
| 959 | @smallexample |
| 960 | gdb -batch -nx -mapped -readnow programname |
| 961 | @end smallexample |
| 962 | |
| 963 | @node Mode Options |
| 964 | @subsection Choosing modes |
| 965 | |
| 966 | You can run @value{GDBN} in various alternative modes---for example, in |
| 967 | batch mode or quiet mode. |
| 968 | |
| 969 | @table @code |
| 970 | @item -nx |
| 971 | @itemx -n |
| 972 | @cindex @code{--nx} |
| 973 | @cindex @code{-n} |
| 974 | Do not execute commands found in any initialization files. Normally, |
| 975 | @value{GDBN} executes the commands in these files after all the command |
| 976 | options and arguments have been processed. @xref{Command Files,,Command |
| 977 | files}. |
| 978 | |
| 979 | @item -quiet |
| 980 | @itemx -silent |
| 981 | @itemx -q |
| 982 | @cindex @code{--quiet} |
| 983 | @cindex @code{--silent} |
| 984 | @cindex @code{-q} |
| 985 | ``Quiet''. Do not print the introductory and copyright messages. These |
| 986 | messages are also suppressed in batch mode. |
| 987 | |
| 988 | @item -batch |
| 989 | @cindex @code{--batch} |
| 990 | Run in batch mode. Exit with status @code{0} after processing all the |
| 991 | command files specified with @samp{-x} (and all commands from |
| 992 | initialization files, if not inhibited with @samp{-n}). Exit with |
| 993 | nonzero status if an error occurs in executing the @value{GDBN} commands |
| 994 | in the command files. |
| 995 | |
| 996 | Batch mode may be useful for running @value{GDBN} as a filter, for |
| 997 | example to download and run a program on another computer; in order to |
| 998 | make this more useful, the message |
| 999 | |
| 1000 | @smallexample |
| 1001 | Program exited normally. |
| 1002 | @end smallexample |
| 1003 | |
| 1004 | @noindent |
| 1005 | (which is ordinarily issued whenever a program running under |
| 1006 | @value{GDBN} control terminates) is not issued when running in batch |
| 1007 | mode. |
| 1008 | |
| 1009 | @item -nowindows |
| 1010 | @itemx -nw |
| 1011 | @cindex @code{--nowindows} |
| 1012 | @cindex @code{-nw} |
| 1013 | ``No windows''. If @value{GDBN} comes with a graphical user interface |
| 1014 | (GUI) built in, then this option tells @value{GDBN} to only use the command-line |
| 1015 | interface. If no GUI is available, this option has no effect. |
| 1016 | |
| 1017 | @item -windows |
| 1018 | @itemx -w |
| 1019 | @cindex @code{--windows} |
| 1020 | @cindex @code{-w} |
| 1021 | If @value{GDBN} includes a GUI, then this option requires it to be |
| 1022 | used if possible. |
| 1023 | |
| 1024 | @item -cd @var{directory} |
| 1025 | @cindex @code{--cd} |
| 1026 | Run @value{GDBN} using @var{directory} as its working directory, |
| 1027 | instead of the current directory. |
| 1028 | |
| 1029 | @item -fullname |
| 1030 | @itemx -f |
| 1031 | @cindex @code{--fullname} |
| 1032 | @cindex @code{-f} |
| 1033 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a |
| 1034 | subprocess. It tells @value{GDBN} to output the full file name and line |
| 1035 | number in a standard, recognizable fashion each time a stack frame is |
| 1036 | displayed (which includes each time your program stops). This |
| 1037 | recognizable format looks like two @samp{\032} characters, followed by |
| 1038 | the file name, line number and character position separated by colons, |
| 1039 | and a newline. The Emacs-to-@value{GDBN} interface program uses the two |
| 1040 | @samp{\032} characters as a signal to display the source code for the |
| 1041 | frame. |
| 1042 | |
| 1043 | @item -epoch |
| 1044 | @cindex @code{--epoch} |
| 1045 | The Epoch Emacs-@value{GDBN} interface sets this option when it runs |
| 1046 | @value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print |
| 1047 | routines so as to allow Epoch to display values of expressions in a |
| 1048 | separate window. |
| 1049 | |
| 1050 | @item -annotate @var{level} |
| 1051 | @cindex @code{--annotate} |
| 1052 | This option sets the @dfn{annotation level} inside @value{GDBN}. Its |
| 1053 | effect is identical to using @samp{set annotate @var{level}} |
| 1054 | (@pxref{Annotations}). |
| 1055 | Annotation level controls how much information does @value{GDBN} print |
| 1056 | together with its prompt, values of expressions, source lines, and other |
| 1057 | types of output. Level 0 is the normal, level 1 is for use when |
| 1058 | @value{GDBN} is run as a subprocess of @sc{gnu} Emacs, level 2 is the |
| 1059 | maximum annotation suitable for programs that control @value{GDBN}. |
| 1060 | |
| 1061 | @item -async |
| 1062 | @cindex @code{--async} |
| 1063 | Use the asynchronous event loop for the command-line interface. |
| 1064 | @value{GDBN} processes all events, such as user keyboard input, via a |
| 1065 | special event loop. This allows @value{GDBN} to accept and process user |
| 1066 | commands in parallel with the debugged process being |
| 1067 | run@footnote{@value{GDBN} built with @sc{djgpp} tools for |
| 1068 | MS-DOS/MS-Windows supports this mode of operation, but the event loop is |
| 1069 | suspended when the debuggee runs.}, so you don't need to wait for |
| 1070 | control to return to @value{GDBN} before you type the next command. |
| 1071 | (@emph{Note:} as of version 5.1, the target side of the asynchronous |
| 1072 | operation is not yet in place, so @samp{-async} does not work fully |
| 1073 | yet.) |
| 1074 | @c FIXME: when the target side of the event loop is done, the above NOTE |
| 1075 | @c should be removed. |
| 1076 | |
| 1077 | When the standard input is connected to a terminal device, @value{GDBN} |
| 1078 | uses the asynchronous event loop by default, unless disabled by the |
| 1079 | @samp{-noasync} option. |
| 1080 | |
| 1081 | @item -noasync |
| 1082 | @cindex @code{--noasync} |
| 1083 | Disable the asynchronous event loop for the command-line interface. |
| 1084 | |
| 1085 | @item --args |
| 1086 | @cindex @code{--args} |
| 1087 | Change interpretation of command line so that arguments following the |
| 1088 | executable file are passed as command line arguments to the inferior. |
| 1089 | This option stops option processing. |
| 1090 | |
| 1091 | @item -baud @var{bps} |
| 1092 | @itemx -b @var{bps} |
| 1093 | @cindex @code{--baud} |
| 1094 | @cindex @code{-b} |
| 1095 | Set the line speed (baud rate or bits per second) of any serial |
| 1096 | interface used by @value{GDBN} for remote debugging. |
| 1097 | |
| 1098 | @item -tty @var{device} |
| 1099 | @itemx -t @var{device} |
| 1100 | @cindex @code{--tty} |
| 1101 | @cindex @code{-t} |
| 1102 | Run using @var{device} for your program's standard input and output. |
| 1103 | @c FIXME: kingdon thinks there is more to -tty. Investigate. |
| 1104 | |
| 1105 | @c resolve the situation of these eventually |
| 1106 | @item -tui |
| 1107 | @cindex @code{--tui} |
| 1108 | Activate the Terminal User Interface when starting. |
| 1109 | The Terminal User Interface manages several text windows on the terminal, |
| 1110 | showing source, assembly, registers and @value{GDBN} command outputs |
| 1111 | (@pxref{TUI, ,@value{GDBN} Text User Interface}). |
| 1112 | Do not use this option if you run @value{GDBN} from Emacs |
| 1113 | (@pxref{Emacs, ,Using @value{GDBN} under @sc{gnu} Emacs}). |
| 1114 | |
| 1115 | @c @item -xdb |
| 1116 | @c @cindex @code{--xdb} |
| 1117 | @c Run in XDB compatibility mode, allowing the use of certain XDB commands. |
| 1118 | @c For information, see the file @file{xdb_trans.html}, which is usually |
| 1119 | @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX |
| 1120 | @c systems. |
| 1121 | |
| 1122 | @item -interpreter @var{interp} |
| 1123 | @cindex @code{--interpreter} |
| 1124 | Use the interpreter @var{interp} for interface with the controlling |
| 1125 | program or device. This option is meant to be set by programs which |
| 1126 | communicate with @value{GDBN} using it as a back end. |
| 1127 | |
| 1128 | @samp{--interpreter=mi} (or @samp{--interpreter=mi2}) causes |
| 1129 | @value{GDBN} to use the current @dfn{@sc{gdb/mi} interface} |
| 1130 | (@pxref{GDB/MI, , The @sc{gdb/mi} Interface}). The previous @sc{gdb/mi} |
| 1131 | interface, included in @value{GDBN} version 5.3, can be selected with |
| 1132 | @samp{--interpreter=mi1}. Earlier @sc{gdb/mi} interfaces |
| 1133 | are not supported. |
| 1134 | |
| 1135 | @item -write |
| 1136 | @cindex @code{--write} |
| 1137 | Open the executable and core files for both reading and writing. This |
| 1138 | is equivalent to the @samp{set write on} command inside @value{GDBN} |
| 1139 | (@pxref{Patching}). |
| 1140 | |
| 1141 | @item -statistics |
| 1142 | @cindex @code{--statistics} |
| 1143 | This option causes @value{GDBN} to print statistics about time and |
| 1144 | memory usage after it completes each command and returns to the prompt. |
| 1145 | |
| 1146 | @item -version |
| 1147 | @cindex @code{--version} |
| 1148 | This option causes @value{GDBN} to print its version number and |
| 1149 | no-warranty blurb, and exit. |
| 1150 | |
| 1151 | @end table |
| 1152 | |
| 1153 | @node Quitting GDB |
| 1154 | @section Quitting @value{GDBN} |
| 1155 | @cindex exiting @value{GDBN} |
| 1156 | @cindex leaving @value{GDBN} |
| 1157 | |
| 1158 | @table @code |
| 1159 | @kindex quit @r{[}@var{expression}@r{]} |
| 1160 | @kindex q @r{(@code{quit})} |
| 1161 | @item quit @r{[}@var{expression}@r{]} |
| 1162 | @itemx q |
| 1163 | To exit @value{GDBN}, use the @code{quit} command (abbreviated |
| 1164 | @code{q}), or type an end-of-file character (usually @kbd{C-d}). If you |
| 1165 | do not supply @var{expression}, @value{GDBN} will terminate normally; |
| 1166 | otherwise it will terminate using the result of @var{expression} as the |
| 1167 | error code. |
| 1168 | @end table |
| 1169 | |
| 1170 | @cindex interrupt |
| 1171 | An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather |
| 1172 | terminates the action of any @value{GDBN} command that is in progress and |
| 1173 | returns to @value{GDBN} command level. It is safe to type the interrupt |
| 1174 | character at any time because @value{GDBN} does not allow it to take effect |
| 1175 | until a time when it is safe. |
| 1176 | |
| 1177 | If you have been using @value{GDBN} to control an attached process or |
| 1178 | device, you can release it with the @code{detach} command |
| 1179 | (@pxref{Attach, ,Debugging an already-running process}). |
| 1180 | |
| 1181 | @node Shell Commands |
| 1182 | @section Shell commands |
| 1183 | |
| 1184 | If you need to execute occasional shell commands during your |
| 1185 | debugging session, there is no need to leave or suspend @value{GDBN}; you can |
| 1186 | just use the @code{shell} command. |
| 1187 | |
| 1188 | @table @code |
| 1189 | @kindex shell |
| 1190 | @cindex shell escape |
| 1191 | @item shell @var{command string} |
| 1192 | Invoke a standard shell to execute @var{command string}. |
| 1193 | If it exists, the environment variable @code{SHELL} determines which |
| 1194 | shell to run. Otherwise @value{GDBN} uses the default shell |
| 1195 | (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.). |
| 1196 | @end table |
| 1197 | |
| 1198 | The utility @code{make} is often needed in development environments. |
| 1199 | You do not have to use the @code{shell} command for this purpose in |
| 1200 | @value{GDBN}: |
| 1201 | |
| 1202 | @table @code |
| 1203 | @kindex make |
| 1204 | @cindex calling make |
| 1205 | @item make @var{make-args} |
| 1206 | Execute the @code{make} program with the specified |
| 1207 | arguments. This is equivalent to @samp{shell make @var{make-args}}. |
| 1208 | @end table |
| 1209 | |
| 1210 | @node Commands |
| 1211 | @chapter @value{GDBN} Commands |
| 1212 | |
| 1213 | You can abbreviate a @value{GDBN} command to the first few letters of the command |
| 1214 | name, if that abbreviation is unambiguous; and you can repeat certain |
| 1215 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} |
| 1216 | key to get @value{GDBN} to fill out the rest of a word in a command (or to |
| 1217 | show you the alternatives available, if there is more than one possibility). |
| 1218 | |
| 1219 | @menu |
| 1220 | * Command Syntax:: How to give commands to @value{GDBN} |
| 1221 | * Completion:: Command completion |
| 1222 | * Help:: How to ask @value{GDBN} for help |
| 1223 | @end menu |
| 1224 | |
| 1225 | @node Command Syntax |
| 1226 | @section Command syntax |
| 1227 | |
| 1228 | A @value{GDBN} command is a single line of input. There is no limit on |
| 1229 | how long it can be. It starts with a command name, which is followed by |
| 1230 | arguments whose meaning depends on the command name. For example, the |
| 1231 | command @code{step} accepts an argument which is the number of times to |
| 1232 | step, as in @samp{step 5}. You can also use the @code{step} command |
| 1233 | with no arguments. Some commands do not allow any arguments. |
| 1234 | |
| 1235 | @cindex abbreviation |
| 1236 | @value{GDBN} command names may always be truncated if that abbreviation is |
| 1237 | unambiguous. Other possible command abbreviations are listed in the |
| 1238 | documentation for individual commands. In some cases, even ambiguous |
| 1239 | abbreviations are allowed; for example, @code{s} is specially defined as |
| 1240 | equivalent to @code{step} even though there are other commands whose |
| 1241 | names start with @code{s}. You can test abbreviations by using them as |
| 1242 | arguments to the @code{help} command. |
| 1243 | |
| 1244 | @cindex repeating commands |
| 1245 | @kindex RET @r{(repeat last command)} |
| 1246 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to |
| 1247 | repeat the previous command. Certain commands (for example, @code{run}) |
| 1248 | will not repeat this way; these are commands whose unintentional |
| 1249 | repetition might cause trouble and which you are unlikely to want to |
| 1250 | repeat. |
| 1251 | |
| 1252 | The @code{list} and @code{x} commands, when you repeat them with |
| 1253 | @key{RET}, construct new arguments rather than repeating |
| 1254 | exactly as typed. This permits easy scanning of source or memory. |
| 1255 | |
| 1256 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy |
| 1257 | output, in a way similar to the common utility @code{more} |
| 1258 | (@pxref{Screen Size,,Screen size}). Since it is easy to press one |
| 1259 | @key{RET} too many in this situation, @value{GDBN} disables command |
| 1260 | repetition after any command that generates this sort of display. |
| 1261 | |
| 1262 | @kindex # @r{(a comment)} |
| 1263 | @cindex comment |
| 1264 | Any text from a @kbd{#} to the end of the line is a comment; it does |
| 1265 | nothing. This is useful mainly in command files (@pxref{Command |
| 1266 | Files,,Command files}). |
| 1267 | |
| 1268 | @cindex repeating command sequences |
| 1269 | @kindex C-o @r{(operate-and-get-next)} |
| 1270 | The @kbd{C-o} binding is useful for repeating a complex sequence of |
| 1271 | commands. This command accepts the current line, like @kbd{RET}, and |
| 1272 | then fetches the next line relative to the current line from the history |
| 1273 | for editing. |
| 1274 | |
| 1275 | @node Completion |
| 1276 | @section Command completion |
| 1277 | |
| 1278 | @cindex completion |
| 1279 | @cindex word completion |
| 1280 | @value{GDBN} can fill in the rest of a word in a command for you, if there is |
| 1281 | only one possibility; it can also show you what the valid possibilities |
| 1282 | are for the next word in a command, at any time. This works for @value{GDBN} |
| 1283 | commands, @value{GDBN} subcommands, and the names of symbols in your program. |
| 1284 | |
| 1285 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest |
| 1286 | of a word. If there is only one possibility, @value{GDBN} fills in the |
| 1287 | word, and waits for you to finish the command (or press @key{RET} to |
| 1288 | enter it). For example, if you type |
| 1289 | |
| 1290 | @c FIXME "@key" does not distinguish its argument sufficiently to permit |
| 1291 | @c complete accuracy in these examples; space introduced for clarity. |
| 1292 | @c If texinfo enhancements make it unnecessary, it would be nice to |
| 1293 | @c replace " @key" by "@key" in the following... |
| 1294 | @smallexample |
| 1295 | (@value{GDBP}) info bre @key{TAB} |
| 1296 | @end smallexample |
| 1297 | |
| 1298 | @noindent |
| 1299 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is |
| 1300 | the only @code{info} subcommand beginning with @samp{bre}: |
| 1301 | |
| 1302 | @smallexample |
| 1303 | (@value{GDBP}) info breakpoints |
| 1304 | @end smallexample |
| 1305 | |
| 1306 | @noindent |
| 1307 | You can either press @key{RET} at this point, to run the @code{info |
| 1308 | breakpoints} command, or backspace and enter something else, if |
| 1309 | @samp{breakpoints} does not look like the command you expected. (If you |
| 1310 | were sure you wanted @code{info breakpoints} in the first place, you |
| 1311 | might as well just type @key{RET} immediately after @samp{info bre}, |
| 1312 | to exploit command abbreviations rather than command completion). |
| 1313 | |
| 1314 | If there is more than one possibility for the next word when you press |
| 1315 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more |
| 1316 | characters and try again, or just press @key{TAB} a second time; |
| 1317 | @value{GDBN} displays all the possible completions for that word. For |
| 1318 | example, you might want to set a breakpoint on a subroutine whose name |
| 1319 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} |
| 1320 | just sounds the bell. Typing @key{TAB} again displays all the |
| 1321 | function names in your program that begin with those characters, for |
| 1322 | example: |
| 1323 | |
| 1324 | @smallexample |
| 1325 | (@value{GDBP}) b make_ @key{TAB} |
| 1326 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: |
| 1327 | make_a_section_from_file make_environ |
| 1328 | make_abs_section make_function_type |
| 1329 | make_blockvector make_pointer_type |
| 1330 | make_cleanup make_reference_type |
| 1331 | make_command make_symbol_completion_list |
| 1332 | (@value{GDBP}) b make_ |
| 1333 | @end smallexample |
| 1334 | |
| 1335 | @noindent |
| 1336 | After displaying the available possibilities, @value{GDBN} copies your |
| 1337 | partial input (@samp{b make_} in the example) so you can finish the |
| 1338 | command. |
| 1339 | |
| 1340 | If you just want to see the list of alternatives in the first place, you |
| 1341 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} |
| 1342 | means @kbd{@key{META} ?}. You can type this either by holding down a |
| 1343 | key designated as the @key{META} shift on your keyboard (if there is |
| 1344 | one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}. |
| 1345 | |
| 1346 | @cindex quotes in commands |
| 1347 | @cindex completion of quoted strings |
| 1348 | Sometimes the string you need, while logically a ``word'', may contain |
| 1349 | parentheses or other characters that @value{GDBN} normally excludes from |
| 1350 | its notion of a word. To permit word completion to work in this |
| 1351 | situation, you may enclose words in @code{'} (single quote marks) in |
| 1352 | @value{GDBN} commands. |
| 1353 | |
| 1354 | The most likely situation where you might need this is in typing the |
| 1355 | name of a C@t{++} function. This is because C@t{++} allows function |
| 1356 | overloading (multiple definitions of the same function, distinguished |
| 1357 | by argument type). For example, when you want to set a breakpoint you |
| 1358 | may need to distinguish whether you mean the version of @code{name} |
| 1359 | that takes an @code{int} parameter, @code{name(int)}, or the version |
| 1360 | that takes a @code{float} parameter, @code{name(float)}. To use the |
| 1361 | word-completion facilities in this situation, type a single quote |
| 1362 | @code{'} at the beginning of the function name. This alerts |
| 1363 | @value{GDBN} that it may need to consider more information than usual |
| 1364 | when you press @key{TAB} or @kbd{M-?} to request word completion: |
| 1365 | |
| 1366 | @smallexample |
| 1367 | (@value{GDBP}) b 'bubble( @kbd{M-?} |
| 1368 | bubble(double,double) bubble(int,int) |
| 1369 | (@value{GDBP}) b 'bubble( |
| 1370 | @end smallexample |
| 1371 | |
| 1372 | In some cases, @value{GDBN} can tell that completing a name requires using |
| 1373 | quotes. When this happens, @value{GDBN} inserts the quote for you (while |
| 1374 | completing as much as it can) if you do not type the quote in the first |
| 1375 | place: |
| 1376 | |
| 1377 | @smallexample |
| 1378 | (@value{GDBP}) b bub @key{TAB} |
| 1379 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: |
| 1380 | (@value{GDBP}) b 'bubble( |
| 1381 | @end smallexample |
| 1382 | |
| 1383 | @noindent |
| 1384 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if |
| 1385 | you have not yet started typing the argument list when you ask for |
| 1386 | completion on an overloaded symbol. |
| 1387 | |
| 1388 | For more information about overloaded functions, see @ref{C plus plus |
| 1389 | expressions, ,C@t{++} expressions}. You can use the command @code{set |
| 1390 | overload-resolution off} to disable overload resolution; |
| 1391 | see @ref{Debugging C plus plus, ,@value{GDBN} features for C@t{++}}. |
| 1392 | |
| 1393 | |
| 1394 | @node Help |
| 1395 | @section Getting help |
| 1396 | @cindex online documentation |
| 1397 | @kindex help |
| 1398 | |
| 1399 | You can always ask @value{GDBN} itself for information on its commands, |
| 1400 | using the command @code{help}. |
| 1401 | |
| 1402 | @table @code |
| 1403 | @kindex h @r{(@code{help})} |
| 1404 | @item help |
| 1405 | @itemx h |
| 1406 | You can use @code{help} (abbreviated @code{h}) with no arguments to |
| 1407 | display a short list of named classes of commands: |
| 1408 | |
| 1409 | @smallexample |
| 1410 | (@value{GDBP}) help |
| 1411 | List of classes of commands: |
| 1412 | |
| 1413 | aliases -- Aliases of other commands |
| 1414 | breakpoints -- Making program stop at certain points |
| 1415 | data -- Examining data |
| 1416 | files -- Specifying and examining files |
| 1417 | internals -- Maintenance commands |
| 1418 | obscure -- Obscure features |
| 1419 | running -- Running the program |
| 1420 | stack -- Examining the stack |
| 1421 | status -- Status inquiries |
| 1422 | support -- Support facilities |
| 1423 | tracepoints -- Tracing of program execution without@* |
| 1424 | stopping the program |
| 1425 | user-defined -- User-defined commands |
| 1426 | |
| 1427 | Type "help" followed by a class name for a list of |
| 1428 | commands in that class. |
| 1429 | Type "help" followed by command name for full |
| 1430 | documentation. |
| 1431 | Command name abbreviations are allowed if unambiguous. |
| 1432 | (@value{GDBP}) |
| 1433 | @end smallexample |
| 1434 | @c the above line break eliminates huge line overfull... |
| 1435 | |
| 1436 | @item help @var{class} |
| 1437 | Using one of the general help classes as an argument, you can get a |
| 1438 | list of the individual commands in that class. For example, here is the |
| 1439 | help display for the class @code{status}: |
| 1440 | |
| 1441 | @smallexample |
| 1442 | (@value{GDBP}) help status |
| 1443 | Status inquiries. |
| 1444 | |
| 1445 | List of commands: |
| 1446 | |
| 1447 | @c Line break in "show" line falsifies real output, but needed |
| 1448 | @c to fit in smallbook page size. |
| 1449 | info -- Generic command for showing things |
| 1450 | about the program being debugged |
| 1451 | show -- Generic command for showing things |
| 1452 | about the debugger |
| 1453 | |
| 1454 | Type "help" followed by command name for full |
| 1455 | documentation. |
| 1456 | Command name abbreviations are allowed if unambiguous. |
| 1457 | (@value{GDBP}) |
| 1458 | @end smallexample |
| 1459 | |
| 1460 | @item help @var{command} |
| 1461 | With a command name as @code{help} argument, @value{GDBN} displays a |
| 1462 | short paragraph on how to use that command. |
| 1463 | |
| 1464 | @kindex apropos |
| 1465 | @item apropos @var{args} |
| 1466 | The @code{apropos @var{args}} command searches through all of the @value{GDBN} |
| 1467 | commands, and their documentation, for the regular expression specified in |
| 1468 | @var{args}. It prints out all matches found. For example: |
| 1469 | |
| 1470 | @smallexample |
| 1471 | apropos reload |
| 1472 | @end smallexample |
| 1473 | |
| 1474 | @noindent |
| 1475 | results in: |
| 1476 | |
| 1477 | @smallexample |
| 1478 | @c @group |
| 1479 | set symbol-reloading -- Set dynamic symbol table reloading |
| 1480 | multiple times in one run |
| 1481 | show symbol-reloading -- Show dynamic symbol table reloading |
| 1482 | multiple times in one run |
| 1483 | @c @end group |
| 1484 | @end smallexample |
| 1485 | |
| 1486 | @kindex complete |
| 1487 | @item complete @var{args} |
| 1488 | The @code{complete @var{args}} command lists all the possible completions |
| 1489 | for the beginning of a command. Use @var{args} to specify the beginning of the |
| 1490 | command you want completed. For example: |
| 1491 | |
| 1492 | @smallexample |
| 1493 | complete i |
| 1494 | @end smallexample |
| 1495 | |
| 1496 | @noindent results in: |
| 1497 | |
| 1498 | @smallexample |
| 1499 | @group |
| 1500 | if |
| 1501 | ignore |
| 1502 | info |
| 1503 | inspect |
| 1504 | @end group |
| 1505 | @end smallexample |
| 1506 | |
| 1507 | @noindent This is intended for use by @sc{gnu} Emacs. |
| 1508 | @end table |
| 1509 | |
| 1510 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} |
| 1511 | and @code{show} to inquire about the state of your program, or the state |
| 1512 | of @value{GDBN} itself. Each command supports many topics of inquiry; this |
| 1513 | manual introduces each of them in the appropriate context. The listings |
| 1514 | under @code{info} and under @code{show} in the Index point to |
| 1515 | all the sub-commands. @xref{Index}. |
| 1516 | |
| 1517 | @c @group |
| 1518 | @table @code |
| 1519 | @kindex info |
| 1520 | @kindex i @r{(@code{info})} |
| 1521 | @item info |
| 1522 | This command (abbreviated @code{i}) is for describing the state of your |
| 1523 | program. For example, you can list the arguments given to your program |
| 1524 | with @code{info args}, list the registers currently in use with @code{info |
| 1525 | registers}, or list the breakpoints you have set with @code{info breakpoints}. |
| 1526 | You can get a complete list of the @code{info} sub-commands with |
| 1527 | @w{@code{help info}}. |
| 1528 | |
| 1529 | @kindex set |
| 1530 | @item set |
| 1531 | You can assign the result of an expression to an environment variable with |
| 1532 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with |
| 1533 | @code{set prompt $}. |
| 1534 | |
| 1535 | @kindex show |
| 1536 | @item show |
| 1537 | In contrast to @code{info}, @code{show} is for describing the state of |
| 1538 | @value{GDBN} itself. |
| 1539 | You can change most of the things you can @code{show}, by using the |
| 1540 | related command @code{set}; for example, you can control what number |
| 1541 | system is used for displays with @code{set radix}, or simply inquire |
| 1542 | which is currently in use with @code{show radix}. |
| 1543 | |
| 1544 | @kindex info set |
| 1545 | To display all the settable parameters and their current |
| 1546 | values, you can use @code{show} with no arguments; you may also use |
| 1547 | @code{info set}. Both commands produce the same display. |
| 1548 | @c FIXME: "info set" violates the rule that "info" is for state of |
| 1549 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, |
| 1550 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? |
| 1551 | @end table |
| 1552 | @c @end group |
| 1553 | |
| 1554 | Here are three miscellaneous @code{show} subcommands, all of which are |
| 1555 | exceptional in lacking corresponding @code{set} commands: |
| 1556 | |
| 1557 | @table @code |
| 1558 | @kindex show version |
| 1559 | @cindex version number |
| 1560 | @item show version |
| 1561 | Show what version of @value{GDBN} is running. You should include this |
| 1562 | information in @value{GDBN} bug-reports. If multiple versions of |
| 1563 | @value{GDBN} are in use at your site, you may need to determine which |
| 1564 | version of @value{GDBN} you are running; as @value{GDBN} evolves, new |
| 1565 | commands are introduced, and old ones may wither away. Also, many |
| 1566 | system vendors ship variant versions of @value{GDBN}, and there are |
| 1567 | variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well. |
| 1568 | The version number is the same as the one announced when you start |
| 1569 | @value{GDBN}. |
| 1570 | |
| 1571 | @kindex show copying |
| 1572 | @item show copying |
| 1573 | Display information about permission for copying @value{GDBN}. |
| 1574 | |
| 1575 | @kindex show warranty |
| 1576 | @item show warranty |
| 1577 | Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty, |
| 1578 | if your version of @value{GDBN} comes with one. |
| 1579 | |
| 1580 | @end table |
| 1581 | |
| 1582 | @node Running |
| 1583 | @chapter Running Programs Under @value{GDBN} |
| 1584 | |
| 1585 | When you run a program under @value{GDBN}, you must first generate |
| 1586 | debugging information when you compile it. |
| 1587 | |
| 1588 | You may start @value{GDBN} with its arguments, if any, in an environment |
| 1589 | of your choice. If you are doing native debugging, you may redirect |
| 1590 | your program's input and output, debug an already running process, or |
| 1591 | kill a child process. |
| 1592 | |
| 1593 | @menu |
| 1594 | * Compilation:: Compiling for debugging |
| 1595 | * Starting:: Starting your program |
| 1596 | * Arguments:: Your program's arguments |
| 1597 | * Environment:: Your program's environment |
| 1598 | |
| 1599 | * Working Directory:: Your program's working directory |
| 1600 | * Input/Output:: Your program's input and output |
| 1601 | * Attach:: Debugging an already-running process |
| 1602 | * Kill Process:: Killing the child process |
| 1603 | |
| 1604 | * Threads:: Debugging programs with multiple threads |
| 1605 | * Processes:: Debugging programs with multiple processes |
| 1606 | @end menu |
| 1607 | |
| 1608 | @node Compilation |
| 1609 | @section Compiling for debugging |
| 1610 | |
| 1611 | In order to debug a program effectively, you need to generate |
| 1612 | debugging information when you compile it. This debugging information |
| 1613 | is stored in the object file; it describes the data type of each |
| 1614 | variable or function and the correspondence between source line numbers |
| 1615 | and addresses in the executable code. |
| 1616 | |
| 1617 | To request debugging information, specify the @samp{-g} option when you run |
| 1618 | the compiler. |
| 1619 | |
| 1620 | Most compilers do not include information about preprocessor macros in |
| 1621 | the debugging information if you specify the @option{-g} flag alone, |
| 1622 | because this information is rather large. Version 3.1 of @value{NGCC}, |
| 1623 | the @sc{gnu} C compiler, provides macro information if you specify the |
| 1624 | options @option{-gdwarf-2} and @option{-g3}; the former option requests |
| 1625 | debugging information in the Dwarf 2 format, and the latter requests |
| 1626 | ``extra information''. In the future, we hope to find more compact ways |
| 1627 | to represent macro information, so that it can be included with |
| 1628 | @option{-g} alone. |
| 1629 | |
| 1630 | Many C compilers are unable to handle the @samp{-g} and @samp{-O} |
| 1631 | options together. Using those compilers, you cannot generate optimized |
| 1632 | executables containing debugging information. |
| 1633 | |
| 1634 | @value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or |
| 1635 | without @samp{-O}, making it possible to debug optimized code. We |
| 1636 | recommend that you @emph{always} use @samp{-g} whenever you compile a |
| 1637 | program. You may think your program is correct, but there is no sense |
| 1638 | in pushing your luck. |
| 1639 | |
| 1640 | @cindex optimized code, debugging |
| 1641 | @cindex debugging optimized code |
| 1642 | When you debug a program compiled with @samp{-g -O}, remember that the |
| 1643 | optimizer is rearranging your code; the debugger shows you what is |
| 1644 | really there. Do not be too surprised when the execution path does not |
| 1645 | exactly match your source file! An extreme example: if you define a |
| 1646 | variable, but never use it, @value{GDBN} never sees that |
| 1647 | variable---because the compiler optimizes it out of existence. |
| 1648 | |
| 1649 | Some things do not work as well with @samp{-g -O} as with just |
| 1650 | @samp{-g}, particularly on machines with instruction scheduling. If in |
| 1651 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, |
| 1652 | please report it to us as a bug (including a test case!). |
| 1653 | |
| 1654 | Older versions of the @sc{gnu} C compiler permitted a variant option |
| 1655 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this |
| 1656 | format; if your @sc{gnu} C compiler has this option, do not use it. |
| 1657 | |
| 1658 | @need 2000 |
| 1659 | @node Starting |
| 1660 | @section Starting your program |
| 1661 | @cindex starting |
| 1662 | @cindex running |
| 1663 | |
| 1664 | @table @code |
| 1665 | @kindex run |
| 1666 | @kindex r @r{(@code{run})} |
| 1667 | @item run |
| 1668 | @itemx r |
| 1669 | Use the @code{run} command to start your program under @value{GDBN}. |
| 1670 | You must first specify the program name (except on VxWorks) with an |
| 1671 | argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of |
| 1672 | @value{GDBN}}), or by using the @code{file} or @code{exec-file} command |
| 1673 | (@pxref{Files, ,Commands to specify files}). |
| 1674 | |
| 1675 | @end table |
| 1676 | |
| 1677 | If you are running your program in an execution environment that |
| 1678 | supports processes, @code{run} creates an inferior process and makes |
| 1679 | that process run your program. (In environments without processes, |
| 1680 | @code{run} jumps to the start of your program.) |
| 1681 | |
| 1682 | The execution of a program is affected by certain information it |
| 1683 | receives from its superior. @value{GDBN} provides ways to specify this |
| 1684 | information, which you must do @emph{before} starting your program. (You |
| 1685 | can change it after starting your program, but such changes only affect |
| 1686 | your program the next time you start it.) This information may be |
| 1687 | divided into four categories: |
| 1688 | |
| 1689 | @table @asis |
| 1690 | @item The @emph{arguments.} |
| 1691 | Specify the arguments to give your program as the arguments of the |
| 1692 | @code{run} command. If a shell is available on your target, the shell |
| 1693 | is used to pass the arguments, so that you may use normal conventions |
| 1694 | (such as wildcard expansion or variable substitution) in describing |
| 1695 | the arguments. |
| 1696 | In Unix systems, you can control which shell is used with the |
| 1697 | @code{SHELL} environment variable. |
| 1698 | @xref{Arguments, ,Your program's arguments}. |
| 1699 | |
| 1700 | @item The @emph{environment.} |
| 1701 | Your program normally inherits its environment from @value{GDBN}, but you can |
| 1702 | use the @value{GDBN} commands @code{set environment} and @code{unset |
| 1703 | environment} to change parts of the environment that affect |
| 1704 | your program. @xref{Environment, ,Your program's environment}. |
| 1705 | |
| 1706 | @item The @emph{working directory.} |
| 1707 | Your program inherits its working directory from @value{GDBN}. You can set |
| 1708 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. |
| 1709 | @xref{Working Directory, ,Your program's working directory}. |
| 1710 | |
| 1711 | @item The @emph{standard input and output.} |
| 1712 | Your program normally uses the same device for standard input and |
| 1713 | standard output as @value{GDBN} is using. You can redirect input and output |
| 1714 | in the @code{run} command line, or you can use the @code{tty} command to |
| 1715 | set a different device for your program. |
| 1716 | @xref{Input/Output, ,Your program's input and output}. |
| 1717 | |
| 1718 | @cindex pipes |
| 1719 | @emph{Warning:} While input and output redirection work, you cannot use |
| 1720 | pipes to pass the output of the program you are debugging to another |
| 1721 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the |
| 1722 | wrong program. |
| 1723 | @end table |
| 1724 | |
| 1725 | When you issue the @code{run} command, your program begins to execute |
| 1726 | immediately. @xref{Stopping, ,Stopping and continuing}, for discussion |
| 1727 | of how to arrange for your program to stop. Once your program has |
| 1728 | stopped, you may call functions in your program, using the @code{print} |
| 1729 | or @code{call} commands. @xref{Data, ,Examining Data}. |
| 1730 | |
| 1731 | If the modification time of your symbol file has changed since the last |
| 1732 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol |
| 1733 | table, and reads it again. When it does this, @value{GDBN} tries to retain |
| 1734 | your current breakpoints. |
| 1735 | |
| 1736 | @node Arguments |
| 1737 | @section Your program's arguments |
| 1738 | |
| 1739 | @cindex arguments (to your program) |
| 1740 | The arguments to your program can be specified by the arguments of the |
| 1741 | @code{run} command. |
| 1742 | They are passed to a shell, which expands wildcard characters and |
| 1743 | performs redirection of I/O, and thence to your program. Your |
| 1744 | @code{SHELL} environment variable (if it exists) specifies what shell |
| 1745 | @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses |
| 1746 | the default shell (@file{/bin/sh} on Unix). |
| 1747 | |
| 1748 | On non-Unix systems, the program is usually invoked directly by |
| 1749 | @value{GDBN}, which emulates I/O redirection via the appropriate system |
| 1750 | calls, and the wildcard characters are expanded by the startup code of |
| 1751 | the program, not by the shell. |
| 1752 | |
| 1753 | @code{run} with no arguments uses the same arguments used by the previous |
| 1754 | @code{run}, or those set by the @code{set args} command. |
| 1755 | |
| 1756 | @table @code |
| 1757 | @kindex set args |
| 1758 | @item set args |
| 1759 | Specify the arguments to be used the next time your program is run. If |
| 1760 | @code{set args} has no arguments, @code{run} executes your program |
| 1761 | with no arguments. Once you have run your program with arguments, |
| 1762 | using @code{set args} before the next @code{run} is the only way to run |
| 1763 | it again without arguments. |
| 1764 | |
| 1765 | @kindex show args |
| 1766 | @item show args |
| 1767 | Show the arguments to give your program when it is started. |
| 1768 | @end table |
| 1769 | |
| 1770 | @node Environment |
| 1771 | @section Your program's environment |
| 1772 | |
| 1773 | @cindex environment (of your program) |
| 1774 | The @dfn{environment} consists of a set of environment variables and |
| 1775 | their values. Environment variables conventionally record such things as |
| 1776 | your user name, your home directory, your terminal type, and your search |
| 1777 | path for programs to run. Usually you set up environment variables with |
| 1778 | the shell and they are inherited by all the other programs you run. When |
| 1779 | debugging, it can be useful to try running your program with a modified |
| 1780 | environment without having to start @value{GDBN} over again. |
| 1781 | |
| 1782 | @table @code |
| 1783 | @kindex path |
| 1784 | @item path @var{directory} |
| 1785 | Add @var{directory} to the front of the @code{PATH} environment variable |
| 1786 | (the search path for executables) that will be passed to your program. |
| 1787 | The value of @code{PATH} used by @value{GDBN} does not change. |
| 1788 | You may specify several directory names, separated by whitespace or by a |
| 1789 | system-dependent separator character (@samp{:} on Unix, @samp{;} on |
| 1790 | MS-DOS and MS-Windows). If @var{directory} is already in the path, it |
| 1791 | is moved to the front, so it is searched sooner. |
| 1792 | |
| 1793 | You can use the string @samp{$cwd} to refer to whatever is the current |
| 1794 | working directory at the time @value{GDBN} searches the path. If you |
| 1795 | use @samp{.} instead, it refers to the directory where you executed the |
| 1796 | @code{path} command. @value{GDBN} replaces @samp{.} in the |
| 1797 | @var{directory} argument (with the current path) before adding |
| 1798 | @var{directory} to the search path. |
| 1799 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to |
| 1800 | @c document that, since repeating it would be a no-op. |
| 1801 | |
| 1802 | @kindex show paths |
| 1803 | @item show paths |
| 1804 | Display the list of search paths for executables (the @code{PATH} |
| 1805 | environment variable). |
| 1806 | |
| 1807 | @kindex show environment |
| 1808 | @item show environment @r{[}@var{varname}@r{]} |
| 1809 | Print the value of environment variable @var{varname} to be given to |
| 1810 | your program when it starts. If you do not supply @var{varname}, |
| 1811 | print the names and values of all environment variables to be given to |
| 1812 | your program. You can abbreviate @code{environment} as @code{env}. |
| 1813 | |
| 1814 | @kindex set environment |
| 1815 | @item set environment @var{varname} @r{[}=@var{value}@r{]} |
| 1816 | Set environment variable @var{varname} to @var{value}. The value |
| 1817 | changes for your program only, not for @value{GDBN} itself. @var{value} may |
| 1818 | be any string; the values of environment variables are just strings, and |
| 1819 | any interpretation is supplied by your program itself. The @var{value} |
| 1820 | parameter is optional; if it is eliminated, the variable is set to a |
| 1821 | null value. |
| 1822 | @c "any string" here does not include leading, trailing |
| 1823 | @c blanks. Gnu asks: does anyone care? |
| 1824 | |
| 1825 | For example, this command: |
| 1826 | |
| 1827 | @smallexample |
| 1828 | set env USER = foo |
| 1829 | @end smallexample |
| 1830 | |
| 1831 | @noindent |
| 1832 | tells the debugged program, when subsequently run, that its user is named |
| 1833 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they |
| 1834 | are not actually required.) |
| 1835 | |
| 1836 | @kindex unset environment |
| 1837 | @item unset environment @var{varname} |
| 1838 | Remove variable @var{varname} from the environment to be passed to your |
| 1839 | program. This is different from @samp{set env @var{varname} =}; |
| 1840 | @code{unset environment} removes the variable from the environment, |
| 1841 | rather than assigning it an empty value. |
| 1842 | @end table |
| 1843 | |
| 1844 | @emph{Warning:} On Unix systems, @value{GDBN} runs your program using |
| 1845 | the shell indicated |
| 1846 | by your @code{SHELL} environment variable if it exists (or |
| 1847 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell |
| 1848 | that runs an initialization file---such as @file{.cshrc} for C-shell, or |
| 1849 | @file{.bashrc} for BASH---any variables you set in that file affect |
| 1850 | your program. You may wish to move setting of environment variables to |
| 1851 | files that are only run when you sign on, such as @file{.login} or |
| 1852 | @file{.profile}. |
| 1853 | |
| 1854 | @node Working Directory |
| 1855 | @section Your program's working directory |
| 1856 | |
| 1857 | @cindex working directory (of your program) |
| 1858 | Each time you start your program with @code{run}, it inherits its |
| 1859 | working directory from the current working directory of @value{GDBN}. |
| 1860 | The @value{GDBN} working directory is initially whatever it inherited |
| 1861 | from its parent process (typically the shell), but you can specify a new |
| 1862 | working directory in @value{GDBN} with the @code{cd} command. |
| 1863 | |
| 1864 | The @value{GDBN} working directory also serves as a default for the commands |
| 1865 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to |
| 1866 | specify files}. |
| 1867 | |
| 1868 | @table @code |
| 1869 | @kindex cd |
| 1870 | @item cd @var{directory} |
| 1871 | Set the @value{GDBN} working directory to @var{directory}. |
| 1872 | |
| 1873 | @kindex pwd |
| 1874 | @item pwd |
| 1875 | Print the @value{GDBN} working directory. |
| 1876 | @end table |
| 1877 | |
| 1878 | @node Input/Output |
| 1879 | @section Your program's input and output |
| 1880 | |
| 1881 | @cindex redirection |
| 1882 | @cindex i/o |
| 1883 | @cindex terminal |
| 1884 | By default, the program you run under @value{GDBN} does input and output to |
| 1885 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal |
| 1886 | to its own terminal modes to interact with you, but it records the terminal |
| 1887 | modes your program was using and switches back to them when you continue |
| 1888 | running your program. |
| 1889 | |
| 1890 | @table @code |
| 1891 | @kindex info terminal |
| 1892 | @item info terminal |
| 1893 | Displays information recorded by @value{GDBN} about the terminal modes your |
| 1894 | program is using. |
| 1895 | @end table |
| 1896 | |
| 1897 | You can redirect your program's input and/or output using shell |
| 1898 | redirection with the @code{run} command. For example, |
| 1899 | |
| 1900 | @smallexample |
| 1901 | run > outfile |
| 1902 | @end smallexample |
| 1903 | |
| 1904 | @noindent |
| 1905 | starts your program, diverting its output to the file @file{outfile}. |
| 1906 | |
| 1907 | @kindex tty |
| 1908 | @cindex controlling terminal |
| 1909 | Another way to specify where your program should do input and output is |
| 1910 | with the @code{tty} command. This command accepts a file name as |
| 1911 | argument, and causes this file to be the default for future @code{run} |
| 1912 | commands. It also resets the controlling terminal for the child |
| 1913 | process, for future @code{run} commands. For example, |
| 1914 | |
| 1915 | @smallexample |
| 1916 | tty /dev/ttyb |
| 1917 | @end smallexample |
| 1918 | |
| 1919 | @noindent |
| 1920 | directs that processes started with subsequent @code{run} commands |
| 1921 | default to do input and output on the terminal @file{/dev/ttyb} and have |
| 1922 | that as their controlling terminal. |
| 1923 | |
| 1924 | An explicit redirection in @code{run} overrides the @code{tty} command's |
| 1925 | effect on the input/output device, but not its effect on the controlling |
| 1926 | terminal. |
| 1927 | |
| 1928 | When you use the @code{tty} command or redirect input in the @code{run} |
| 1929 | command, only the input @emph{for your program} is affected. The input |
| 1930 | for @value{GDBN} still comes from your terminal. |
| 1931 | |
| 1932 | @node Attach |
| 1933 | @section Debugging an already-running process |
| 1934 | @kindex attach |
| 1935 | @cindex attach |
| 1936 | |
| 1937 | @table @code |
| 1938 | @item attach @var{process-id} |
| 1939 | This command attaches to a running process---one that was started |
| 1940 | outside @value{GDBN}. (@code{info files} shows your active |
| 1941 | targets.) The command takes as argument a process ID. The usual way to |
| 1942 | find out the process-id of a Unix process is with the @code{ps} utility, |
| 1943 | or with the @samp{jobs -l} shell command. |
| 1944 | |
| 1945 | @code{attach} does not repeat if you press @key{RET} a second time after |
| 1946 | executing the command. |
| 1947 | @end table |
| 1948 | |
| 1949 | To use @code{attach}, your program must be running in an environment |
| 1950 | which supports processes; for example, @code{attach} does not work for |
| 1951 | programs on bare-board targets that lack an operating system. You must |
| 1952 | also have permission to send the process a signal. |
| 1953 | |
| 1954 | When you use @code{attach}, the debugger finds the program running in |
| 1955 | the process first by looking in the current working directory, then (if |
| 1956 | the program is not found) by using the source file search path |
| 1957 | (@pxref{Source Path, ,Specifying source directories}). You can also use |
| 1958 | the @code{file} command to load the program. @xref{Files, ,Commands to |
| 1959 | Specify Files}. |
| 1960 | |
| 1961 | The first thing @value{GDBN} does after arranging to debug the specified |
| 1962 | process is to stop it. You can examine and modify an attached process |
| 1963 | with all the @value{GDBN} commands that are ordinarily available when |
| 1964 | you start processes with @code{run}. You can insert breakpoints; you |
| 1965 | can step and continue; you can modify storage. If you would rather the |
| 1966 | process continue running, you may use the @code{continue} command after |
| 1967 | attaching @value{GDBN} to the process. |
| 1968 | |
| 1969 | @table @code |
| 1970 | @kindex detach |
| 1971 | @item detach |
| 1972 | When you have finished debugging the attached process, you can use the |
| 1973 | @code{detach} command to release it from @value{GDBN} control. Detaching |
| 1974 | the process continues its execution. After the @code{detach} command, |
| 1975 | that process and @value{GDBN} become completely independent once more, and you |
| 1976 | are ready to @code{attach} another process or start one with @code{run}. |
| 1977 | @code{detach} does not repeat if you press @key{RET} again after |
| 1978 | executing the command. |
| 1979 | @end table |
| 1980 | |
| 1981 | If you exit @value{GDBN} or use the @code{run} command while you have an |
| 1982 | attached process, you kill that process. By default, @value{GDBN} asks |
| 1983 | for confirmation if you try to do either of these things; you can |
| 1984 | control whether or not you need to confirm by using the @code{set |
| 1985 | confirm} command (@pxref{Messages/Warnings, ,Optional warnings and |
| 1986 | messages}). |
| 1987 | |
| 1988 | @node Kill Process |
| 1989 | @section Killing the child process |
| 1990 | |
| 1991 | @table @code |
| 1992 | @kindex kill |
| 1993 | @item kill |
| 1994 | Kill the child process in which your program is running under @value{GDBN}. |
| 1995 | @end table |
| 1996 | |
| 1997 | This command is useful if you wish to debug a core dump instead of a |
| 1998 | running process. @value{GDBN} ignores any core dump file while your program |
| 1999 | is running. |
| 2000 | |
| 2001 | On some operating systems, a program cannot be executed outside @value{GDBN} |
| 2002 | while you have breakpoints set on it inside @value{GDBN}. You can use the |
| 2003 | @code{kill} command in this situation to permit running your program |
| 2004 | outside the debugger. |
| 2005 | |
| 2006 | The @code{kill} command is also useful if you wish to recompile and |
| 2007 | relink your program, since on many systems it is impossible to modify an |
| 2008 | executable file while it is running in a process. In this case, when you |
| 2009 | next type @code{run}, @value{GDBN} notices that the file has changed, and |
| 2010 | reads the symbol table again (while trying to preserve your current |
| 2011 | breakpoint settings). |
| 2012 | |
| 2013 | @node Threads |
| 2014 | @section Debugging programs with multiple threads |
| 2015 | |
| 2016 | @cindex threads of execution |
| 2017 | @cindex multiple threads |
| 2018 | @cindex switching threads |
| 2019 | In some operating systems, such as HP-UX and Solaris, a single program |
| 2020 | may have more than one @dfn{thread} of execution. The precise semantics |
| 2021 | of threads differ from one operating system to another, but in general |
| 2022 | the threads of a single program are akin to multiple processes---except |
| 2023 | that they share one address space (that is, they can all examine and |
| 2024 | modify the same variables). On the other hand, each thread has its own |
| 2025 | registers and execution stack, and perhaps private memory. |
| 2026 | |
| 2027 | @value{GDBN} provides these facilities for debugging multi-thread |
| 2028 | programs: |
| 2029 | |
| 2030 | @itemize @bullet |
| 2031 | @item automatic notification of new threads |
| 2032 | @item @samp{thread @var{threadno}}, a command to switch among threads |
| 2033 | @item @samp{info threads}, a command to inquire about existing threads |
| 2034 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, |
| 2035 | a command to apply a command to a list of threads |
| 2036 | @item thread-specific breakpoints |
| 2037 | @end itemize |
| 2038 | |
| 2039 | @quotation |
| 2040 | @emph{Warning:} These facilities are not yet available on every |
| 2041 | @value{GDBN} configuration where the operating system supports threads. |
| 2042 | If your @value{GDBN} does not support threads, these commands have no |
| 2043 | effect. For example, a system without thread support shows no output |
| 2044 | from @samp{info threads}, and always rejects the @code{thread} command, |
| 2045 | like this: |
| 2046 | |
| 2047 | @smallexample |
| 2048 | (@value{GDBP}) info threads |
| 2049 | (@value{GDBP}) thread 1 |
| 2050 | Thread ID 1 not known. Use the "info threads" command to |
| 2051 | see the IDs of currently known threads. |
| 2052 | @end smallexample |
| 2053 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB |
| 2054 | @c doesn't support threads"? |
| 2055 | @end quotation |
| 2056 | |
| 2057 | @cindex focus of debugging |
| 2058 | @cindex current thread |
| 2059 | The @value{GDBN} thread debugging facility allows you to observe all |
| 2060 | threads while your program runs---but whenever @value{GDBN} takes |
| 2061 | control, one thread in particular is always the focus of debugging. |
| 2062 | This thread is called the @dfn{current thread}. Debugging commands show |
| 2063 | program information from the perspective of the current thread. |
| 2064 | |
| 2065 | @cindex @code{New} @var{systag} message |
| 2066 | @cindex thread identifier (system) |
| 2067 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
| 2068 | @c included GDB's numeric thread handle, so you could just go to that |
| 2069 | @c thread without first checking `info threads'. |
| 2070 | Whenever @value{GDBN} detects a new thread in your program, it displays |
| 2071 | the target system's identification for the thread with a message in the |
| 2072 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier |
| 2073 | whose form varies depending on the particular system. For example, on |
| 2074 | LynxOS, you might see |
| 2075 | |
| 2076 | @smallexample |
| 2077 | [New process 35 thread 27] |
| 2078 | @end smallexample |
| 2079 | |
| 2080 | @noindent |
| 2081 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, |
| 2082 | the @var{systag} is simply something like @samp{process 368}, with no |
| 2083 | further qualifier. |
| 2084 | |
| 2085 | @c FIXME!! (1) Does the [New...] message appear even for the very first |
| 2086 | @c thread of a program, or does it only appear for the |
| 2087 | @c second---i.e.@: when it becomes obvious we have a multithread |
| 2088 | @c program? |
| 2089 | @c (2) *Is* there necessarily a first thread always? Or do some |
| 2090 | @c multithread systems permit starting a program with multiple |
| 2091 | @c threads ab initio? |
| 2092 | |
| 2093 | @cindex thread number |
| 2094 | @cindex thread identifier (GDB) |
| 2095 | For debugging purposes, @value{GDBN} associates its own thread |
| 2096 | number---always a single integer---with each thread in your program. |
| 2097 | |
| 2098 | @table @code |
| 2099 | @kindex info threads |
| 2100 | @item info threads |
| 2101 | Display a summary of all threads currently in your |
| 2102 | program. @value{GDBN} displays for each thread (in this order): |
| 2103 | |
| 2104 | @enumerate |
| 2105 | @item the thread number assigned by @value{GDBN} |
| 2106 | |
| 2107 | @item the target system's thread identifier (@var{systag}) |
| 2108 | |
| 2109 | @item the current stack frame summary for that thread |
| 2110 | @end enumerate |
| 2111 | |
| 2112 | @noindent |
| 2113 | An asterisk @samp{*} to the left of the @value{GDBN} thread number |
| 2114 | indicates the current thread. |
| 2115 | |
| 2116 | For example, |
| 2117 | @end table |
| 2118 | @c end table here to get a little more width for example |
| 2119 | |
| 2120 | @smallexample |
| 2121 | (@value{GDBP}) info threads |
| 2122 | 3 process 35 thread 27 0x34e5 in sigpause () |
| 2123 | 2 process 35 thread 23 0x34e5 in sigpause () |
| 2124 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) |
| 2125 | at threadtest.c:68 |
| 2126 | @end smallexample |
| 2127 | |
| 2128 | On HP-UX systems: |
| 2129 | |
| 2130 | @cindex thread number |
| 2131 | @cindex thread identifier (GDB) |
| 2132 | For debugging purposes, @value{GDBN} associates its own thread |
| 2133 | number---a small integer assigned in thread-creation order---with each |
| 2134 | thread in your program. |
| 2135 | |
| 2136 | @cindex @code{New} @var{systag} message, on HP-UX |
| 2137 | @cindex thread identifier (system), on HP-UX |
| 2138 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
| 2139 | @c included GDB's numeric thread handle, so you could just go to that |
| 2140 | @c thread without first checking `info threads'. |
| 2141 | Whenever @value{GDBN} detects a new thread in your program, it displays |
| 2142 | both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the |
| 2143 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier |
| 2144 | whose form varies depending on the particular system. For example, on |
| 2145 | HP-UX, you see |
| 2146 | |
| 2147 | @smallexample |
| 2148 | [New thread 2 (system thread 26594)] |
| 2149 | @end smallexample |
| 2150 | |
| 2151 | @noindent |
| 2152 | when @value{GDBN} notices a new thread. |
| 2153 | |
| 2154 | @table @code |
| 2155 | @kindex info threads |
| 2156 | @item info threads |
| 2157 | Display a summary of all threads currently in your |
| 2158 | program. @value{GDBN} displays for each thread (in this order): |
| 2159 | |
| 2160 | @enumerate |
| 2161 | @item the thread number assigned by @value{GDBN} |
| 2162 | |
| 2163 | @item the target system's thread identifier (@var{systag}) |
| 2164 | |
| 2165 | @item the current stack frame summary for that thread |
| 2166 | @end enumerate |
| 2167 | |
| 2168 | @noindent |
| 2169 | An asterisk @samp{*} to the left of the @value{GDBN} thread number |
| 2170 | indicates the current thread. |
| 2171 | |
| 2172 | For example, |
| 2173 | @end table |
| 2174 | @c end table here to get a little more width for example |
| 2175 | |
| 2176 | @smallexample |
| 2177 | (@value{GDBP}) info threads |
| 2178 | * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") \@* |
| 2179 | at quicksort.c:137 |
| 2180 | 2 system thread 26606 0x7b0030d8 in __ksleep () \@* |
| 2181 | from /usr/lib/libc.2 |
| 2182 | 1 system thread 27905 0x7b003498 in _brk () \@* |
| 2183 | from /usr/lib/libc.2 |
| 2184 | @end smallexample |
| 2185 | |
| 2186 | @table @code |
| 2187 | @kindex thread @var{threadno} |
| 2188 | @item thread @var{threadno} |
| 2189 | Make thread number @var{threadno} the current thread. The command |
| 2190 | argument @var{threadno} is the internal @value{GDBN} thread number, as |
| 2191 | shown in the first field of the @samp{info threads} display. |
| 2192 | @value{GDBN} responds by displaying the system identifier of the thread |
| 2193 | you selected, and its current stack frame summary: |
| 2194 | |
| 2195 | @smallexample |
| 2196 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one |
| 2197 | (@value{GDBP}) thread 2 |
| 2198 | [Switching to process 35 thread 23] |
| 2199 | 0x34e5 in sigpause () |
| 2200 | @end smallexample |
| 2201 | |
| 2202 | @noindent |
| 2203 | As with the @samp{[New @dots{}]} message, the form of the text after |
| 2204 | @samp{Switching to} depends on your system's conventions for identifying |
| 2205 | threads. |
| 2206 | |
| 2207 | @kindex thread apply |
| 2208 | @item thread apply [@var{threadno}] [@var{all}] @var{args} |
| 2209 | The @code{thread apply} command allows you to apply a command to one or |
| 2210 | more threads. Specify the numbers of the threads that you want affected |
| 2211 | with the command argument @var{threadno}. @var{threadno} is the internal |
| 2212 | @value{GDBN} thread number, as shown in the first field of the @samp{info |
| 2213 | threads} display. To apply a command to all threads, use |
| 2214 | @code{thread apply all} @var{args}. |
| 2215 | @end table |
| 2216 | |
| 2217 | @cindex automatic thread selection |
| 2218 | @cindex switching threads automatically |
| 2219 | @cindex threads, automatic switching |
| 2220 | Whenever @value{GDBN} stops your program, due to a breakpoint or a |
| 2221 | signal, it automatically selects the thread where that breakpoint or |
| 2222 | signal happened. @value{GDBN} alerts you to the context switch with a |
| 2223 | message of the form @samp{[Switching to @var{systag}]} to identify the |
| 2224 | thread. |
| 2225 | |
| 2226 | @xref{Thread Stops,,Stopping and starting multi-thread programs}, for |
| 2227 | more information about how @value{GDBN} behaves when you stop and start |
| 2228 | programs with multiple threads. |
| 2229 | |
| 2230 | @xref{Set Watchpoints,,Setting watchpoints}, for information about |
| 2231 | watchpoints in programs with multiple threads. |
| 2232 | |
| 2233 | @node Processes |
| 2234 | @section Debugging programs with multiple processes |
| 2235 | |
| 2236 | @cindex fork, debugging programs which call |
| 2237 | @cindex multiple processes |
| 2238 | @cindex processes, multiple |
| 2239 | On most systems, @value{GDBN} has no special support for debugging |
| 2240 | programs which create additional processes using the @code{fork} |
| 2241 | function. When a program forks, @value{GDBN} will continue to debug the |
| 2242 | parent process and the child process will run unimpeded. If you have |
| 2243 | set a breakpoint in any code which the child then executes, the child |
| 2244 | will get a @code{SIGTRAP} signal which (unless it catches the signal) |
| 2245 | will cause it to terminate. |
| 2246 | |
| 2247 | However, if you want to debug the child process there is a workaround |
| 2248 | which isn't too painful. Put a call to @code{sleep} in the code which |
| 2249 | the child process executes after the fork. It may be useful to sleep |
| 2250 | only if a certain environment variable is set, or a certain file exists, |
| 2251 | so that the delay need not occur when you don't want to run @value{GDBN} |
| 2252 | on the child. While the child is sleeping, use the @code{ps} program to |
| 2253 | get its process ID. Then tell @value{GDBN} (a new invocation of |
| 2254 | @value{GDBN} if you are also debugging the parent process) to attach to |
| 2255 | the child process (@pxref{Attach}). From that point on you can debug |
| 2256 | the child process just like any other process which you attached to. |
| 2257 | |
| 2258 | On HP-UX (11.x and later only?), @value{GDBN} provides support for |
| 2259 | debugging programs that create additional processes using the |
| 2260 | @code{fork} or @code{vfork} function. |
| 2261 | |
| 2262 | By default, when a program forks, @value{GDBN} will continue to debug |
| 2263 | the parent process and the child process will run unimpeded. |
| 2264 | |
| 2265 | If you want to follow the child process instead of the parent process, |
| 2266 | use the command @w{@code{set follow-fork-mode}}. |
| 2267 | |
| 2268 | @table @code |
| 2269 | @kindex set follow-fork-mode |
| 2270 | @item set follow-fork-mode @var{mode} |
| 2271 | Set the debugger response to a program call of @code{fork} or |
| 2272 | @code{vfork}. A call to @code{fork} or @code{vfork} creates a new |
| 2273 | process. The @var{mode} can be: |
| 2274 | |
| 2275 | @table @code |
| 2276 | @item parent |
| 2277 | The original process is debugged after a fork. The child process runs |
| 2278 | unimpeded. This is the default. |
| 2279 | |
| 2280 | @item child |
| 2281 | The new process is debugged after a fork. The parent process runs |
| 2282 | unimpeded. |
| 2283 | |
| 2284 | @item ask |
| 2285 | The debugger will ask for one of the above choices. |
| 2286 | @end table |
| 2287 | |
| 2288 | @item show follow-fork-mode |
| 2289 | Display the current debugger response to a @code{fork} or @code{vfork} call. |
| 2290 | @end table |
| 2291 | |
| 2292 | If you ask to debug a child process and a @code{vfork} is followed by an |
| 2293 | @code{exec}, @value{GDBN} executes the new target up to the first |
| 2294 | breakpoint in the new target. If you have a breakpoint set on |
| 2295 | @code{main} in your original program, the breakpoint will also be set on |
| 2296 | the child process's @code{main}. |
| 2297 | |
| 2298 | When a child process is spawned by @code{vfork}, you cannot debug the |
| 2299 | child or parent until an @code{exec} call completes. |
| 2300 | |
| 2301 | If you issue a @code{run} command to @value{GDBN} after an @code{exec} |
| 2302 | call executes, the new target restarts. To restart the parent process, |
| 2303 | use the @code{file} command with the parent executable name as its |
| 2304 | argument. |
| 2305 | |
| 2306 | You can use the @code{catch} command to make @value{GDBN} stop whenever |
| 2307 | a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set |
| 2308 | Catchpoints, ,Setting catchpoints}. |
| 2309 | |
| 2310 | @node Stopping |
| 2311 | @chapter Stopping and Continuing |
| 2312 | |
| 2313 | The principal purposes of using a debugger are so that you can stop your |
| 2314 | program before it terminates; or so that, if your program runs into |
| 2315 | trouble, you can investigate and find out why. |
| 2316 | |
| 2317 | Inside @value{GDBN}, your program may stop for any of several reasons, |
| 2318 | such as a signal, a breakpoint, or reaching a new line after a |
| 2319 | @value{GDBN} command such as @code{step}. You may then examine and |
| 2320 | change variables, set new breakpoints or remove old ones, and then |
| 2321 | continue execution. Usually, the messages shown by @value{GDBN} provide |
| 2322 | ample explanation of the status of your program---but you can also |
| 2323 | explicitly request this information at any time. |
| 2324 | |
| 2325 | @table @code |
| 2326 | @kindex info program |
| 2327 | @item info program |
| 2328 | Display information about the status of your program: whether it is |
| 2329 | running or not, what process it is, and why it stopped. |
| 2330 | @end table |
| 2331 | |
| 2332 | @menu |
| 2333 | * Breakpoints:: Breakpoints, watchpoints, and catchpoints |
| 2334 | * Continuing and Stepping:: Resuming execution |
| 2335 | * Signals:: Signals |
| 2336 | * Thread Stops:: Stopping and starting multi-thread programs |
| 2337 | @end menu |
| 2338 | |
| 2339 | @node Breakpoints |
| 2340 | @section Breakpoints, watchpoints, and catchpoints |
| 2341 | |
| 2342 | @cindex breakpoints |
| 2343 | A @dfn{breakpoint} makes your program stop whenever a certain point in |
| 2344 | the program is reached. For each breakpoint, you can add conditions to |
| 2345 | control in finer detail whether your program stops. You can set |
| 2346 | breakpoints with the @code{break} command and its variants (@pxref{Set |
| 2347 | Breaks, ,Setting breakpoints}), to specify the place where your program |
| 2348 | should stop by line number, function name or exact address in the |
| 2349 | program. |
| 2350 | |
| 2351 | In HP-UX, SunOS 4.x, SVR4, and Alpha OSF/1 configurations, you can set |
| 2352 | breakpoints in shared libraries before the executable is run. There is |
| 2353 | a minor limitation on HP-UX systems: you must wait until the executable |
| 2354 | is run in order to set breakpoints in shared library routines that are |
| 2355 | not called directly by the program (for example, routines that are |
| 2356 | arguments in a @code{pthread_create} call). |
| 2357 | |
| 2358 | @cindex watchpoints |
| 2359 | @cindex memory tracing |
| 2360 | @cindex breakpoint on memory address |
| 2361 | @cindex breakpoint on variable modification |
| 2362 | A @dfn{watchpoint} is a special breakpoint that stops your program |
| 2363 | when the value of an expression changes. You must use a different |
| 2364 | command to set watchpoints (@pxref{Set Watchpoints, ,Setting |
| 2365 | watchpoints}), but aside from that, you can manage a watchpoint like |
| 2366 | any other breakpoint: you enable, disable, and delete both breakpoints |
| 2367 | and watchpoints using the same commands. |
| 2368 | |
| 2369 | You can arrange to have values from your program displayed automatically |
| 2370 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, |
| 2371 | Automatic display}. |
| 2372 | |
| 2373 | @cindex catchpoints |
| 2374 | @cindex breakpoint on events |
| 2375 | A @dfn{catchpoint} is another special breakpoint that stops your program |
| 2376 | when a certain kind of event occurs, such as the throwing of a C@t{++} |
| 2377 | exception or the loading of a library. As with watchpoints, you use a |
| 2378 | different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting |
| 2379 | catchpoints}), but aside from that, you can manage a catchpoint like any |
| 2380 | other breakpoint. (To stop when your program receives a signal, use the |
| 2381 | @code{handle} command; see @ref{Signals, ,Signals}.) |
| 2382 | |
| 2383 | @cindex breakpoint numbers |
| 2384 | @cindex numbers for breakpoints |
| 2385 | @value{GDBN} assigns a number to each breakpoint, watchpoint, or |
| 2386 | catchpoint when you create it; these numbers are successive integers |
| 2387 | starting with one. In many of the commands for controlling various |
| 2388 | features of breakpoints you use the breakpoint number to say which |
| 2389 | breakpoint you want to change. Each breakpoint may be @dfn{enabled} or |
| 2390 | @dfn{disabled}; if disabled, it has no effect on your program until you |
| 2391 | enable it again. |
| 2392 | |
| 2393 | @cindex breakpoint ranges |
| 2394 | @cindex ranges of breakpoints |
| 2395 | Some @value{GDBN} commands accept a range of breakpoints on which to |
| 2396 | operate. A breakpoint range is either a single breakpoint number, like |
| 2397 | @samp{5}, or two such numbers, in increasing order, separated by a |
| 2398 | hyphen, like @samp{5-7}. When a breakpoint range is given to a command, |
| 2399 | all breakpoint in that range are operated on. |
| 2400 | |
| 2401 | @menu |
| 2402 | * Set Breaks:: Setting breakpoints |
| 2403 | * Set Watchpoints:: Setting watchpoints |
| 2404 | * Set Catchpoints:: Setting catchpoints |
| 2405 | * Delete Breaks:: Deleting breakpoints |
| 2406 | * Disabling:: Disabling breakpoints |
| 2407 | * Conditions:: Break conditions |
| 2408 | * Break Commands:: Breakpoint command lists |
| 2409 | * Breakpoint Menus:: Breakpoint menus |
| 2410 | * Error in Breakpoints:: ``Cannot insert breakpoints'' |
| 2411 | @end menu |
| 2412 | |
| 2413 | @node Set Breaks |
| 2414 | @subsection Setting breakpoints |
| 2415 | |
| 2416 | @c FIXME LMB what does GDB do if no code on line of breakpt? |
| 2417 | @c consider in particular declaration with/without initialization. |
| 2418 | @c |
| 2419 | @c FIXME 2 is there stuff on this already? break at fun start, already init? |
| 2420 | |
| 2421 | @kindex break |
| 2422 | @kindex b @r{(@code{break})} |
| 2423 | @vindex $bpnum@r{, convenience variable} |
| 2424 | @cindex latest breakpoint |
| 2425 | Breakpoints are set with the @code{break} command (abbreviated |
| 2426 | @code{b}). The debugger convenience variable @samp{$bpnum} records the |
| 2427 | number of the breakpoint you've set most recently; see @ref{Convenience |
| 2428 | Vars,, Convenience variables}, for a discussion of what you can do with |
| 2429 | convenience variables. |
| 2430 | |
| 2431 | You have several ways to say where the breakpoint should go. |
| 2432 | |
| 2433 | @table @code |
| 2434 | @item break @var{function} |
| 2435 | Set a breakpoint at entry to function @var{function}. |
| 2436 | When using source languages that permit overloading of symbols, such as |
| 2437 | C@t{++}, @var{function} may refer to more than one possible place to break. |
| 2438 | @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. |
| 2439 | |
| 2440 | @item break +@var{offset} |
| 2441 | @itemx break -@var{offset} |
| 2442 | Set a breakpoint some number of lines forward or back from the position |
| 2443 | at which execution stopped in the currently selected @dfn{stack frame}. |
| 2444 | (@xref{Frames, ,Frames}, for a description of stack frames.) |
| 2445 | |
| 2446 | @item break @var{linenum} |
| 2447 | Set a breakpoint at line @var{linenum} in the current source file. |
| 2448 | The current source file is the last file whose source text was printed. |
| 2449 | The breakpoint will stop your program just before it executes any of the |
| 2450 | code on that line. |
| 2451 | |
| 2452 | @item break @var{filename}:@var{linenum} |
| 2453 | Set a breakpoint at line @var{linenum} in source file @var{filename}. |
| 2454 | |
| 2455 | @item break @var{filename}:@var{function} |
| 2456 | Set a breakpoint at entry to function @var{function} found in file |
| 2457 | @var{filename}. Specifying a file name as well as a function name is |
| 2458 | superfluous except when multiple files contain similarly named |
| 2459 | functions. |
| 2460 | |
| 2461 | @item break *@var{address} |
| 2462 | Set a breakpoint at address @var{address}. You can use this to set |
| 2463 | breakpoints in parts of your program which do not have debugging |
| 2464 | information or source files. |
| 2465 | |
| 2466 | @item break |
| 2467 | When called without any arguments, @code{break} sets a breakpoint at |
| 2468 | the next instruction to be executed in the selected stack frame |
| 2469 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the |
| 2470 | innermost, this makes your program stop as soon as control |
| 2471 | returns to that frame. This is similar to the effect of a |
| 2472 | @code{finish} command in the frame inside the selected frame---except |
| 2473 | that @code{finish} does not leave an active breakpoint. If you use |
| 2474 | @code{break} without an argument in the innermost frame, @value{GDBN} stops |
| 2475 | the next time it reaches the current location; this may be useful |
| 2476 | inside loops. |
| 2477 | |
| 2478 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at |
| 2479 | least one instruction has been executed. If it did not do this, you |
| 2480 | would be unable to proceed past a breakpoint without first disabling the |
| 2481 | breakpoint. This rule applies whether or not the breakpoint already |
| 2482 | existed when your program stopped. |
| 2483 | |
| 2484 | @item break @dots{} if @var{cond} |
| 2485 | Set a breakpoint with condition @var{cond}; evaluate the expression |
| 2486 | @var{cond} each time the breakpoint is reached, and stop only if the |
| 2487 | value is nonzero---that is, if @var{cond} evaluates as true. |
| 2488 | @samp{@dots{}} stands for one of the possible arguments described |
| 2489 | above (or no argument) specifying where to break. @xref{Conditions, |
| 2490 | ,Break conditions}, for more information on breakpoint conditions. |
| 2491 | |
| 2492 | @kindex tbreak |
| 2493 | @item tbreak @var{args} |
| 2494 | Set a breakpoint enabled only for one stop. @var{args} are the |
| 2495 | same as for the @code{break} command, and the breakpoint is set in the same |
| 2496 | way, but the breakpoint is automatically deleted after the first time your |
| 2497 | program stops there. @xref{Disabling, ,Disabling breakpoints}. |
| 2498 | |
| 2499 | @kindex hbreak |
| 2500 | @item hbreak @var{args} |
| 2501 | Set a hardware-assisted breakpoint. @var{args} are the same as for the |
| 2502 | @code{break} command and the breakpoint is set in the same way, but the |
| 2503 | breakpoint requires hardware support and some target hardware may not |
| 2504 | have this support. The main purpose of this is EPROM/ROM code |
| 2505 | debugging, so you can set a breakpoint at an instruction without |
| 2506 | changing the instruction. This can be used with the new trap-generation |
| 2507 | provided by SPARClite DSU and some x86-based targets. These targets |
| 2508 | will generate traps when a program accesses some data or instruction |
| 2509 | address that is assigned to the debug registers. However the hardware |
| 2510 | breakpoint registers can take a limited number of breakpoints. For |
| 2511 | example, on the DSU, only two data breakpoints can be set at a time, and |
| 2512 | @value{GDBN} will reject this command if more than two are used. Delete |
| 2513 | or disable unused hardware breakpoints before setting new ones |
| 2514 | (@pxref{Disabling, ,Disabling}). @xref{Conditions, ,Break conditions}. |
| 2515 | |
| 2516 | @kindex thbreak |
| 2517 | @item thbreak @var{args} |
| 2518 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} |
| 2519 | are the same as for the @code{hbreak} command and the breakpoint is set in |
| 2520 | the same way. However, like the @code{tbreak} command, |
| 2521 | the breakpoint is automatically deleted after the |
| 2522 | first time your program stops there. Also, like the @code{hbreak} |
| 2523 | command, the breakpoint requires hardware support and some target hardware |
| 2524 | may not have this support. @xref{Disabling, ,Disabling breakpoints}. |
| 2525 | See also @ref{Conditions, ,Break conditions}. |
| 2526 | |
| 2527 | @kindex rbreak |
| 2528 | @cindex regular expression |
| 2529 | @item rbreak @var{regex} |
| 2530 | Set breakpoints on all functions matching the regular expression |
| 2531 | @var{regex}. This command sets an unconditional breakpoint on all |
| 2532 | matches, printing a list of all breakpoints it set. Once these |
| 2533 | breakpoints are set, they are treated just like the breakpoints set with |
| 2534 | the @code{break} command. You can delete them, disable them, or make |
| 2535 | them conditional the same way as any other breakpoint. |
| 2536 | |
| 2537 | The syntax of the regular expression is the standard one used with tools |
| 2538 | like @file{grep}. Note that this is different from the syntax used by |
| 2539 | shells, so for instance @code{foo*} matches all functions that include |
| 2540 | an @code{fo} followed by zero or more @code{o}s. There is an implicit |
| 2541 | @code{.*} leading and trailing the regular expression you supply, so to |
| 2542 | match only functions that begin with @code{foo}, use @code{^foo}. |
| 2543 | |
| 2544 | When debugging C@t{++} programs, @code{rbreak} is useful for setting |
| 2545 | breakpoints on overloaded functions that are not members of any special |
| 2546 | classes. |
| 2547 | |
| 2548 | @kindex info breakpoints |
| 2549 | @cindex @code{$_} and @code{info breakpoints} |
| 2550 | @item info breakpoints @r{[}@var{n}@r{]} |
| 2551 | @itemx info break @r{[}@var{n}@r{]} |
| 2552 | @itemx info watchpoints @r{[}@var{n}@r{]} |
| 2553 | Print a table of all breakpoints, watchpoints, and catchpoints set and |
| 2554 | not deleted, with the following columns for each breakpoint: |
| 2555 | |
| 2556 | @table @emph |
| 2557 | @item Breakpoint Numbers |
| 2558 | @item Type |
| 2559 | Breakpoint, watchpoint, or catchpoint. |
| 2560 | @item Disposition |
| 2561 | Whether the breakpoint is marked to be disabled or deleted when hit. |
| 2562 | @item Enabled or Disabled |
| 2563 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints |
| 2564 | that are not enabled. |
| 2565 | @item Address |
| 2566 | Where the breakpoint is in your program, as a memory address. |
| 2567 | @item What |
| 2568 | Where the breakpoint is in the source for your program, as a file and |
| 2569 | line number. |
| 2570 | @end table |
| 2571 | |
| 2572 | @noindent |
| 2573 | If a breakpoint is conditional, @code{info break} shows the condition on |
| 2574 | the line following the affected breakpoint; breakpoint commands, if any, |
| 2575 | are listed after that. |
| 2576 | |
| 2577 | @noindent |
| 2578 | @code{info break} with a breakpoint |
| 2579 | number @var{n} as argument lists only that breakpoint. The |
| 2580 | convenience variable @code{$_} and the default examining-address for |
| 2581 | the @code{x} command are set to the address of the last breakpoint |
| 2582 | listed (@pxref{Memory, ,Examining memory}). |
| 2583 | |
| 2584 | @noindent |
| 2585 | @code{info break} displays a count of the number of times the breakpoint |
| 2586 | has been hit. This is especially useful in conjunction with the |
| 2587 | @code{ignore} command. You can ignore a large number of breakpoint |
| 2588 | hits, look at the breakpoint info to see how many times the breakpoint |
| 2589 | was hit, and then run again, ignoring one less than that number. This |
| 2590 | will get you quickly to the last hit of that breakpoint. |
| 2591 | @end table |
| 2592 | |
| 2593 | @value{GDBN} allows you to set any number of breakpoints at the same place in |
| 2594 | your program. There is nothing silly or meaningless about this. When |
| 2595 | the breakpoints are conditional, this is even useful |
| 2596 | (@pxref{Conditions, ,Break conditions}). |
| 2597 | |
| 2598 | @cindex negative breakpoint numbers |
| 2599 | @cindex internal @value{GDBN} breakpoints |
| 2600 | @value{GDBN} itself sometimes sets breakpoints in your program for |
| 2601 | special purposes, such as proper handling of @code{longjmp} (in C |
| 2602 | programs). These internal breakpoints are assigned negative numbers, |
| 2603 | starting with @code{-1}; @samp{info breakpoints} does not display them. |
| 2604 | You can see these breakpoints with the @value{GDBN} maintenance command |
| 2605 | @samp{maint info breakpoints} (@pxref{maint info breakpoints}). |
| 2606 | |
| 2607 | |
| 2608 | @node Set Watchpoints |
| 2609 | @subsection Setting watchpoints |
| 2610 | |
| 2611 | @cindex setting watchpoints |
| 2612 | @cindex software watchpoints |
| 2613 | @cindex hardware watchpoints |
| 2614 | You can use a watchpoint to stop execution whenever the value of an |
| 2615 | expression changes, without having to predict a particular place where |
| 2616 | this may happen. |
| 2617 | |
| 2618 | Depending on your system, watchpoints may be implemented in software or |
| 2619 | hardware. @value{GDBN} does software watchpointing by single-stepping your |
| 2620 | program and testing the variable's value each time, which is hundreds of |
| 2621 | times slower than normal execution. (But this may still be worth it, to |
| 2622 | catch errors where you have no clue what part of your program is the |
| 2623 | culprit.) |
| 2624 | |
| 2625 | On some systems, such as HP-UX, @sc{gnu}/Linux and some other x86-based targets, |
| 2626 | @value{GDBN} includes support for |
| 2627 | hardware watchpoints, which do not slow down the running of your |
| 2628 | program. |
| 2629 | |
| 2630 | @table @code |
| 2631 | @kindex watch |
| 2632 | @item watch @var{expr} |
| 2633 | Set a watchpoint for an expression. @value{GDBN} will break when @var{expr} |
| 2634 | is written into by the program and its value changes. |
| 2635 | |
| 2636 | @kindex rwatch |
| 2637 | @item rwatch @var{expr} |
| 2638 | Set a watchpoint that will break when watch @var{expr} is read by the program. |
| 2639 | |
| 2640 | @kindex awatch |
| 2641 | @item awatch @var{expr} |
| 2642 | Set a watchpoint that will break when @var{expr} is either read or written into |
| 2643 | by the program. |
| 2644 | |
| 2645 | @kindex info watchpoints |
| 2646 | @item info watchpoints |
| 2647 | This command prints a list of watchpoints, breakpoints, and catchpoints; |
| 2648 | it is the same as @code{info break}. |
| 2649 | @end table |
| 2650 | |
| 2651 | @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware |
| 2652 | watchpoints execute very quickly, and the debugger reports a change in |
| 2653 | value at the exact instruction where the change occurs. If @value{GDBN} |
| 2654 | cannot set a hardware watchpoint, it sets a software watchpoint, which |
| 2655 | executes more slowly and reports the change in value at the next |
| 2656 | statement, not the instruction, after the change occurs. |
| 2657 | |
| 2658 | When you issue the @code{watch} command, @value{GDBN} reports |
| 2659 | |
| 2660 | @smallexample |
| 2661 | Hardware watchpoint @var{num}: @var{expr} |
| 2662 | @end smallexample |
| 2663 | |
| 2664 | @noindent |
| 2665 | if it was able to set a hardware watchpoint. |
| 2666 | |
| 2667 | Currently, the @code{awatch} and @code{rwatch} commands can only set |
| 2668 | hardware watchpoints, because accesses to data that don't change the |
| 2669 | value of the watched expression cannot be detected without examining |
| 2670 | every instruction as it is being executed, and @value{GDBN} does not do |
| 2671 | that currently. If @value{GDBN} finds that it is unable to set a |
| 2672 | hardware breakpoint with the @code{awatch} or @code{rwatch} command, it |
| 2673 | will print a message like this: |
| 2674 | |
| 2675 | @smallexample |
| 2676 | Expression cannot be implemented with read/access watchpoint. |
| 2677 | @end smallexample |
| 2678 | |
| 2679 | Sometimes, @value{GDBN} cannot set a hardware watchpoint because the |
| 2680 | data type of the watched expression is wider than what a hardware |
| 2681 | watchpoint on the target machine can handle. For example, some systems |
| 2682 | can only watch regions that are up to 4 bytes wide; on such systems you |
| 2683 | cannot set hardware watchpoints for an expression that yields a |
| 2684 | double-precision floating-point number (which is typically 8 bytes |
| 2685 | wide). As a work-around, it might be possible to break the large region |
| 2686 | into a series of smaller ones and watch them with separate watchpoints. |
| 2687 | |
| 2688 | If you set too many hardware watchpoints, @value{GDBN} might be unable |
| 2689 | to insert all of them when you resume the execution of your program. |
| 2690 | Since the precise number of active watchpoints is unknown until such |
| 2691 | time as the program is about to be resumed, @value{GDBN} might not be |
| 2692 | able to warn you about this when you set the watchpoints, and the |
| 2693 | warning will be printed only when the program is resumed: |
| 2694 | |
| 2695 | @smallexample |
| 2696 | Hardware watchpoint @var{num}: Could not insert watchpoint |
| 2697 | @end smallexample |
| 2698 | |
| 2699 | @noindent |
| 2700 | If this happens, delete or disable some of the watchpoints. |
| 2701 | |
| 2702 | The SPARClite DSU will generate traps when a program accesses some data |
| 2703 | or instruction address that is assigned to the debug registers. For the |
| 2704 | data addresses, DSU facilitates the @code{watch} command. However the |
| 2705 | hardware breakpoint registers can only take two data watchpoints, and |
| 2706 | both watchpoints must be the same kind. For example, you can set two |
| 2707 | watchpoints with @code{watch} commands, two with @code{rwatch} commands, |
| 2708 | @strong{or} two with @code{awatch} commands, but you cannot set one |
| 2709 | watchpoint with one command and the other with a different command. |
| 2710 | @value{GDBN} will reject the command if you try to mix watchpoints. |
| 2711 | Delete or disable unused watchpoint commands before setting new ones. |
| 2712 | |
| 2713 | If you call a function interactively using @code{print} or @code{call}, |
| 2714 | any watchpoints you have set will be inactive until @value{GDBN} reaches another |
| 2715 | kind of breakpoint or the call completes. |
| 2716 | |
| 2717 | @value{GDBN} automatically deletes watchpoints that watch local |
| 2718 | (automatic) variables, or expressions that involve such variables, when |
| 2719 | they go out of scope, that is, when the execution leaves the block in |
| 2720 | which these variables were defined. In particular, when the program |
| 2721 | being debugged terminates, @emph{all} local variables go out of scope, |
| 2722 | and so only watchpoints that watch global variables remain set. If you |
| 2723 | rerun the program, you will need to set all such watchpoints again. One |
| 2724 | way of doing that would be to set a code breakpoint at the entry to the |
| 2725 | @code{main} function and when it breaks, set all the watchpoints. |
| 2726 | |
| 2727 | @quotation |
| 2728 | @cindex watchpoints and threads |
| 2729 | @cindex threads and watchpoints |
| 2730 | @emph{Warning:} In multi-thread programs, watchpoints have only limited |
| 2731 | usefulness. With the current watchpoint implementation, @value{GDBN} |
| 2732 | can only watch the value of an expression @emph{in a single thread}. If |
| 2733 | you are confident that the expression can only change due to the current |
| 2734 | thread's activity (and if you are also confident that no other thread |
| 2735 | can become current), then you can use watchpoints as usual. However, |
| 2736 | @value{GDBN} may not notice when a non-current thread's activity changes |
| 2737 | the expression. |
| 2738 | |
| 2739 | @c FIXME: this is almost identical to the previous paragraph. |
| 2740 | @emph{HP-UX Warning:} In multi-thread programs, software watchpoints |
| 2741 | have only limited usefulness. If @value{GDBN} creates a software |
| 2742 | watchpoint, it can only watch the value of an expression @emph{in a |
| 2743 | single thread}. If you are confident that the expression can only |
| 2744 | change due to the current thread's activity (and if you are also |
| 2745 | confident that no other thread can become current), then you can use |
| 2746 | software watchpoints as usual. However, @value{GDBN} may not notice |
| 2747 | when a non-current thread's activity changes the expression. (Hardware |
| 2748 | watchpoints, in contrast, watch an expression in all threads.) |
| 2749 | @end quotation |
| 2750 | |
| 2751 | @node Set Catchpoints |
| 2752 | @subsection Setting catchpoints |
| 2753 | @cindex catchpoints, setting |
| 2754 | @cindex exception handlers |
| 2755 | @cindex event handling |
| 2756 | |
| 2757 | You can use @dfn{catchpoints} to cause the debugger to stop for certain |
| 2758 | kinds of program events, such as C@t{++} exceptions or the loading of a |
| 2759 | shared library. Use the @code{catch} command to set a catchpoint. |
| 2760 | |
| 2761 | @table @code |
| 2762 | @kindex catch |
| 2763 | @item catch @var{event} |
| 2764 | Stop when @var{event} occurs. @var{event} can be any of the following: |
| 2765 | @table @code |
| 2766 | @item throw |
| 2767 | @kindex catch throw |
| 2768 | The throwing of a C@t{++} exception. |
| 2769 | |
| 2770 | @item catch |
| 2771 | @kindex catch catch |
| 2772 | The catching of a C@t{++} exception. |
| 2773 | |
| 2774 | @item exec |
| 2775 | @kindex catch exec |
| 2776 | A call to @code{exec}. This is currently only available for HP-UX. |
| 2777 | |
| 2778 | @item fork |
| 2779 | @kindex catch fork |
| 2780 | A call to @code{fork}. This is currently only available for HP-UX. |
| 2781 | |
| 2782 | @item vfork |
| 2783 | @kindex catch vfork |
| 2784 | A call to @code{vfork}. This is currently only available for HP-UX. |
| 2785 | |
| 2786 | @item load |
| 2787 | @itemx load @var{libname} |
| 2788 | @kindex catch load |
| 2789 | The dynamic loading of any shared library, or the loading of the library |
| 2790 | @var{libname}. This is currently only available for HP-UX. |
| 2791 | |
| 2792 | @item unload |
| 2793 | @itemx unload @var{libname} |
| 2794 | @kindex catch unload |
| 2795 | The unloading of any dynamically loaded shared library, or the unloading |
| 2796 | of the library @var{libname}. This is currently only available for HP-UX. |
| 2797 | @end table |
| 2798 | |
| 2799 | @item tcatch @var{event} |
| 2800 | Set a catchpoint that is enabled only for one stop. The catchpoint is |
| 2801 | automatically deleted after the first time the event is caught. |
| 2802 | |
| 2803 | @end table |
| 2804 | |
| 2805 | Use the @code{info break} command to list the current catchpoints. |
| 2806 | |
| 2807 | There are currently some limitations to C@t{++} exception handling |
| 2808 | (@code{catch throw} and @code{catch catch}) in @value{GDBN}: |
| 2809 | |
| 2810 | @itemize @bullet |
| 2811 | @item |
| 2812 | If you call a function interactively, @value{GDBN} normally returns |
| 2813 | control to you when the function has finished executing. If the call |
| 2814 | raises an exception, however, the call may bypass the mechanism that |
| 2815 | returns control to you and cause your program either to abort or to |
| 2816 | simply continue running until it hits a breakpoint, catches a signal |
| 2817 | that @value{GDBN} is listening for, or exits. This is the case even if |
| 2818 | you set a catchpoint for the exception; catchpoints on exceptions are |
| 2819 | disabled within interactive calls. |
| 2820 | |
| 2821 | @item |
| 2822 | You cannot raise an exception interactively. |
| 2823 | |
| 2824 | @item |
| 2825 | You cannot install an exception handler interactively. |
| 2826 | @end itemize |
| 2827 | |
| 2828 | @cindex raise exceptions |
| 2829 | Sometimes @code{catch} is not the best way to debug exception handling: |
| 2830 | if you need to know exactly where an exception is raised, it is better to |
| 2831 | stop @emph{before} the exception handler is called, since that way you |
| 2832 | can see the stack before any unwinding takes place. If you set a |
| 2833 | breakpoint in an exception handler instead, it may not be easy to find |
| 2834 | out where the exception was raised. |
| 2835 | |
| 2836 | To stop just before an exception handler is called, you need some |
| 2837 | knowledge of the implementation. In the case of @sc{gnu} C@t{++}, exceptions are |
| 2838 | raised by calling a library function named @code{__raise_exception} |
| 2839 | which has the following ANSI C interface: |
| 2840 | |
| 2841 | @smallexample |
| 2842 | /* @var{addr} is where the exception identifier is stored. |
| 2843 | @var{id} is the exception identifier. */ |
| 2844 | void __raise_exception (void **addr, void *id); |
| 2845 | @end smallexample |
| 2846 | |
| 2847 | @noindent |
| 2848 | To make the debugger catch all exceptions before any stack |
| 2849 | unwinding takes place, set a breakpoint on @code{__raise_exception} |
| 2850 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). |
| 2851 | |
| 2852 | With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) |
| 2853 | that depends on the value of @var{id}, you can stop your program when |
| 2854 | a specific exception is raised. You can use multiple conditional |
| 2855 | breakpoints to stop your program when any of a number of exceptions are |
| 2856 | raised. |
| 2857 | |
| 2858 | |
| 2859 | @node Delete Breaks |
| 2860 | @subsection Deleting breakpoints |
| 2861 | |
| 2862 | @cindex clearing breakpoints, watchpoints, catchpoints |
| 2863 | @cindex deleting breakpoints, watchpoints, catchpoints |
| 2864 | It is often necessary to eliminate a breakpoint, watchpoint, or |
| 2865 | catchpoint once it has done its job and you no longer want your program |
| 2866 | to stop there. This is called @dfn{deleting} the breakpoint. A |
| 2867 | breakpoint that has been deleted no longer exists; it is forgotten. |
| 2868 | |
| 2869 | With the @code{clear} command you can delete breakpoints according to |
| 2870 | where they are in your program. With the @code{delete} command you can |
| 2871 | delete individual breakpoints, watchpoints, or catchpoints by specifying |
| 2872 | their breakpoint numbers. |
| 2873 | |
| 2874 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} |
| 2875 | automatically ignores breakpoints on the first instruction to be executed |
| 2876 | when you continue execution without changing the execution address. |
| 2877 | |
| 2878 | @table @code |
| 2879 | @kindex clear |
| 2880 | @item clear |
| 2881 | Delete any breakpoints at the next instruction to be executed in the |
| 2882 | selected stack frame (@pxref{Selection, ,Selecting a frame}). When |
| 2883 | the innermost frame is selected, this is a good way to delete a |
| 2884 | breakpoint where your program just stopped. |
| 2885 | |
| 2886 | @item clear @var{function} |
| 2887 | @itemx clear @var{filename}:@var{function} |
| 2888 | Delete any breakpoints set at entry to the function @var{function}. |
| 2889 | |
| 2890 | @item clear @var{linenum} |
| 2891 | @itemx clear @var{filename}:@var{linenum} |
| 2892 | Delete any breakpoints set at or within the code of the specified line. |
| 2893 | |
| 2894 | @cindex delete breakpoints |
| 2895 | @kindex delete |
| 2896 | @kindex d @r{(@code{delete})} |
| 2897 | @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 2898 | Delete the breakpoints, watchpoints, or catchpoints of the breakpoint |
| 2899 | ranges specified as arguments. If no argument is specified, delete all |
| 2900 | breakpoints (@value{GDBN} asks confirmation, unless you have @code{set |
| 2901 | confirm off}). You can abbreviate this command as @code{d}. |
| 2902 | @end table |
| 2903 | |
| 2904 | @node Disabling |
| 2905 | @subsection Disabling breakpoints |
| 2906 | |
| 2907 | @kindex disable breakpoints |
| 2908 | @kindex enable breakpoints |
| 2909 | Rather than deleting a breakpoint, watchpoint, or catchpoint, you might |
| 2910 | prefer to @dfn{disable} it. This makes the breakpoint inoperative as if |
| 2911 | it had been deleted, but remembers the information on the breakpoint so |
| 2912 | that you can @dfn{enable} it again later. |
| 2913 | |
| 2914 | You disable and enable breakpoints, watchpoints, and catchpoints with |
| 2915 | the @code{enable} and @code{disable} commands, optionally specifying one |
| 2916 | or more breakpoint numbers as arguments. Use @code{info break} or |
| 2917 | @code{info watch} to print a list of breakpoints, watchpoints, and |
| 2918 | catchpoints if you do not know which numbers to use. |
| 2919 | |
| 2920 | A breakpoint, watchpoint, or catchpoint can have any of four different |
| 2921 | states of enablement: |
| 2922 | |
| 2923 | @itemize @bullet |
| 2924 | @item |
| 2925 | Enabled. The breakpoint stops your program. A breakpoint set |
| 2926 | with the @code{break} command starts out in this state. |
| 2927 | @item |
| 2928 | Disabled. The breakpoint has no effect on your program. |
| 2929 | @item |
| 2930 | Enabled once. The breakpoint stops your program, but then becomes |
| 2931 | disabled. |
| 2932 | @item |
| 2933 | Enabled for deletion. The breakpoint stops your program, but |
| 2934 | immediately after it does so it is deleted permanently. A breakpoint |
| 2935 | set with the @code{tbreak} command starts out in this state. |
| 2936 | @end itemize |
| 2937 | |
| 2938 | You can use the following commands to enable or disable breakpoints, |
| 2939 | watchpoints, and catchpoints: |
| 2940 | |
| 2941 | @table @code |
| 2942 | @kindex disable breakpoints |
| 2943 | @kindex disable |
| 2944 | @kindex dis @r{(@code{disable})} |
| 2945 | @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 2946 | Disable the specified breakpoints---or all breakpoints, if none are |
| 2947 | listed. A disabled breakpoint has no effect but is not forgotten. All |
| 2948 | options such as ignore-counts, conditions and commands are remembered in |
| 2949 | case the breakpoint is enabled again later. You may abbreviate |
| 2950 | @code{disable} as @code{dis}. |
| 2951 | |
| 2952 | @kindex enable breakpoints |
| 2953 | @kindex enable |
| 2954 | @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
| 2955 | Enable the specified breakpoints (or all defined breakpoints). They |
| 2956 | become effective once again in stopping your program. |
| 2957 | |
| 2958 | @item enable @r{[}breakpoints@r{]} once @var{range}@dots{} |
| 2959 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
| 2960 | of these breakpoints immediately after stopping your program. |
| 2961 | |
| 2962 | @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{} |
| 2963 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
| 2964 | deletes any of these breakpoints as soon as your program stops there. |
| 2965 | @end table |
| 2966 | |
| 2967 | @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is |
| 2968 | @c confusing: tbreak is also initially enabled. |
| 2969 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
| 2970 | ,Setting breakpoints}), breakpoints that you set are initially enabled; |
| 2971 | subsequently, they become disabled or enabled only when you use one of |
| 2972 | the commands above. (The command @code{until} can set and delete a |
| 2973 | breakpoint of its own, but it does not change the state of your other |
| 2974 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and |
| 2975 | stepping}.) |
| 2976 | |
| 2977 | @node Conditions |
| 2978 | @subsection Break conditions |
| 2979 | @cindex conditional breakpoints |
| 2980 | @cindex breakpoint conditions |
| 2981 | |
| 2982 | @c FIXME what is scope of break condition expr? Context where wanted? |
| 2983 | @c in particular for a watchpoint? |
| 2984 | The simplest sort of breakpoint breaks every time your program reaches a |
| 2985 | specified place. You can also specify a @dfn{condition} for a |
| 2986 | breakpoint. A condition is just a Boolean expression in your |
| 2987 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with |
| 2988 | a condition evaluates the expression each time your program reaches it, |
| 2989 | and your program stops only if the condition is @emph{true}. |
| 2990 | |
| 2991 | This is the converse of using assertions for program validation; in that |
| 2992 | situation, you want to stop when the assertion is violated---that is, |
| 2993 | when the condition is false. In C, if you want to test an assertion expressed |
| 2994 | by the condition @var{assert}, you should set the condition |
| 2995 | @samp{! @var{assert}} on the appropriate breakpoint. |
| 2996 | |
| 2997 | Conditions are also accepted for watchpoints; you may not need them, |
| 2998 | since a watchpoint is inspecting the value of an expression anyhow---but |
| 2999 | it might be simpler, say, to just set a watchpoint on a variable name, |
| 3000 | and specify a condition that tests whether the new value is an interesting |
| 3001 | one. |
| 3002 | |
| 3003 | Break conditions can have side effects, and may even call functions in |
| 3004 | your program. This can be useful, for example, to activate functions |
| 3005 | that log program progress, or to use your own print functions to |
| 3006 | format special data structures. The effects are completely predictable |
| 3007 | unless there is another enabled breakpoint at the same address. (In |
| 3008 | that case, @value{GDBN} might see the other breakpoint first and stop your |
| 3009 | program without checking the condition of this one.) Note that |
| 3010 | breakpoint commands are usually more convenient and flexible than break |
| 3011 | conditions for the |
| 3012 | purpose of performing side effects when a breakpoint is reached |
| 3013 | (@pxref{Break Commands, ,Breakpoint command lists}). |
| 3014 | |
| 3015 | Break conditions can be specified when a breakpoint is set, by using |
| 3016 | @samp{if} in the arguments to the @code{break} command. @xref{Set |
| 3017 | Breaks, ,Setting breakpoints}. They can also be changed at any time |
| 3018 | with the @code{condition} command. |
| 3019 | |
| 3020 | You can also use the @code{if} keyword with the @code{watch} command. |
| 3021 | The @code{catch} command does not recognize the @code{if} keyword; |
| 3022 | @code{condition} is the only way to impose a further condition on a |
| 3023 | catchpoint. |
| 3024 | |
| 3025 | @table @code |
| 3026 | @kindex condition |
| 3027 | @item condition @var{bnum} @var{expression} |
| 3028 | Specify @var{expression} as the break condition for breakpoint, |
| 3029 | watchpoint, or catchpoint number @var{bnum}. After you set a condition, |
| 3030 | breakpoint @var{bnum} stops your program only if the value of |
| 3031 | @var{expression} is true (nonzero, in C). When you use |
| 3032 | @code{condition}, @value{GDBN} checks @var{expression} immediately for |
| 3033 | syntactic correctness, and to determine whether symbols in it have |
| 3034 | referents in the context of your breakpoint. If @var{expression} uses |
| 3035 | symbols not referenced in the context of the breakpoint, @value{GDBN} |
| 3036 | prints an error message: |
| 3037 | |
| 3038 | @smallexample |
| 3039 | No symbol "foo" in current context. |
| 3040 | @end smallexample |
| 3041 | |
| 3042 | @noindent |
| 3043 | @value{GDBN} does |
| 3044 | not actually evaluate @var{expression} at the time the @code{condition} |
| 3045 | command (or a command that sets a breakpoint with a condition, like |
| 3046 | @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}. |
| 3047 | |
| 3048 | @item condition @var{bnum} |
| 3049 | Remove the condition from breakpoint number @var{bnum}. It becomes |
| 3050 | an ordinary unconditional breakpoint. |
| 3051 | @end table |
| 3052 | |
| 3053 | @cindex ignore count (of breakpoint) |
| 3054 | A special case of a breakpoint condition is to stop only when the |
| 3055 | breakpoint has been reached a certain number of times. This is so |
| 3056 | useful that there is a special way to do it, using the @dfn{ignore |
| 3057 | count} of the breakpoint. Every breakpoint has an ignore count, which |
| 3058 | is an integer. Most of the time, the ignore count is zero, and |
| 3059 | therefore has no effect. But if your program reaches a breakpoint whose |
| 3060 | ignore count is positive, then instead of stopping, it just decrements |
| 3061 | the ignore count by one and continues. As a result, if the ignore count |
| 3062 | value is @var{n}, the breakpoint does not stop the next @var{n} times |
| 3063 | your program reaches it. |
| 3064 | |
| 3065 | @table @code |
| 3066 | @kindex ignore |
| 3067 | @item ignore @var{bnum} @var{count} |
| 3068 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. |
| 3069 | The next @var{count} times the breakpoint is reached, your program's |
| 3070 | execution does not stop; other than to decrement the ignore count, @value{GDBN} |
| 3071 | takes no action. |
| 3072 | |
| 3073 | To make the breakpoint stop the next time it is reached, specify |
| 3074 | a count of zero. |
| 3075 | |
| 3076 | When you use @code{continue} to resume execution of your program from a |
| 3077 | breakpoint, you can specify an ignore count directly as an argument to |
| 3078 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and |
| 3079 | Stepping,,Continuing and stepping}. |
| 3080 | |
| 3081 | If a breakpoint has a positive ignore count and a condition, the |
| 3082 | condition is not checked. Once the ignore count reaches zero, |
| 3083 | @value{GDBN} resumes checking the condition. |
| 3084 | |
| 3085 | You could achieve the effect of the ignore count with a condition such |
| 3086 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that |
| 3087 | is decremented each time. @xref{Convenience Vars, ,Convenience |
| 3088 | variables}. |
| 3089 | @end table |
| 3090 | |
| 3091 | Ignore counts apply to breakpoints, watchpoints, and catchpoints. |
| 3092 | |
| 3093 | |
| 3094 | @node Break Commands |
| 3095 | @subsection Breakpoint command lists |
| 3096 | |
| 3097 | @cindex breakpoint commands |
| 3098 | You can give any breakpoint (or watchpoint or catchpoint) a series of |
| 3099 | commands to execute when your program stops due to that breakpoint. For |
| 3100 | example, you might want to print the values of certain expressions, or |
| 3101 | enable other breakpoints. |
| 3102 | |
| 3103 | @table @code |
| 3104 | @kindex commands |
| 3105 | @kindex end |
| 3106 | @item commands @r{[}@var{bnum}@r{]} |
| 3107 | @itemx @dots{} @var{command-list} @dots{} |
| 3108 | @itemx end |
| 3109 | Specify a list of commands for breakpoint number @var{bnum}. The commands |
| 3110 | themselves appear on the following lines. Type a line containing just |
| 3111 | @code{end} to terminate the commands. |
| 3112 | |
| 3113 | To remove all commands from a breakpoint, type @code{commands} and |
| 3114 | follow it immediately with @code{end}; that is, give no commands. |
| 3115 | |
| 3116 | With no @var{bnum} argument, @code{commands} refers to the last |
| 3117 | breakpoint, watchpoint, or catchpoint set (not to the breakpoint most |
| 3118 | recently encountered). |
| 3119 | @end table |
| 3120 | |
| 3121 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is |
| 3122 | disabled within a @var{command-list}. |
| 3123 | |
| 3124 | You can use breakpoint commands to start your program up again. Simply |
| 3125 | use the @code{continue} command, or @code{step}, or any other command |
| 3126 | that resumes execution. |
| 3127 | |
| 3128 | Any other commands in the command list, after a command that resumes |
| 3129 | execution, are ignored. This is because any time you resume execution |
| 3130 | (even with a simple @code{next} or @code{step}), you may encounter |
| 3131 | another breakpoint---which could have its own command list, leading to |
| 3132 | ambiguities about which list to execute. |
| 3133 | |
| 3134 | @kindex silent |
| 3135 | If the first command you specify in a command list is @code{silent}, the |
| 3136 | usual message about stopping at a breakpoint is not printed. This may |
| 3137 | be desirable for breakpoints that are to print a specific message and |
| 3138 | then continue. If none of the remaining commands print anything, you |
| 3139 | see no sign that the breakpoint was reached. @code{silent} is |
| 3140 | meaningful only at the beginning of a breakpoint command list. |
| 3141 | |
| 3142 | The commands @code{echo}, @code{output}, and @code{printf} allow you to |
| 3143 | print precisely controlled output, and are often useful in silent |
| 3144 | breakpoints. @xref{Output, ,Commands for controlled output}. |
| 3145 | |
| 3146 | For example, here is how you could use breakpoint commands to print the |
| 3147 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. |
| 3148 | |
| 3149 | @smallexample |
| 3150 | break foo if x>0 |
| 3151 | commands |
| 3152 | silent |
| 3153 | printf "x is %d\n",x |
| 3154 | cont |
| 3155 | end |
| 3156 | @end smallexample |
| 3157 | |
| 3158 | One application for breakpoint commands is to compensate for one bug so |
| 3159 | you can test for another. Put a breakpoint just after the erroneous line |
| 3160 | of code, give it a condition to detect the case in which something |
| 3161 | erroneous has been done, and give it commands to assign correct values |
| 3162 | to any variables that need them. End with the @code{continue} command |
| 3163 | so that your program does not stop, and start with the @code{silent} |
| 3164 | command so that no output is produced. Here is an example: |
| 3165 | |
| 3166 | @smallexample |
| 3167 | break 403 |
| 3168 | commands |
| 3169 | silent |
| 3170 | set x = y + 4 |
| 3171 | cont |
| 3172 | end |
| 3173 | @end smallexample |
| 3174 | |
| 3175 | @node Breakpoint Menus |
| 3176 | @subsection Breakpoint menus |
| 3177 | @cindex overloading |
| 3178 | @cindex symbol overloading |
| 3179 | |
| 3180 | Some programming languages (notably C@t{++}) permit a single function name |
| 3181 | to be defined several times, for application in different contexts. |
| 3182 | This is called @dfn{overloading}. When a function name is overloaded, |
| 3183 | @samp{break @var{function}} is not enough to tell @value{GDBN} where you want |
| 3184 | a breakpoint. If you realize this is a problem, you can use |
| 3185 | something like @samp{break @var{function}(@var{types})} to specify which |
| 3186 | particular version of the function you want. Otherwise, @value{GDBN} offers |
| 3187 | you a menu of numbered choices for different possible breakpoints, and |
| 3188 | waits for your selection with the prompt @samp{>}. The first two |
| 3189 | options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} |
| 3190 | sets a breakpoint at each definition of @var{function}, and typing |
| 3191 | @kbd{0} aborts the @code{break} command without setting any new |
| 3192 | breakpoints. |
| 3193 | |
| 3194 | For example, the following session excerpt shows an attempt to set a |
| 3195 | breakpoint at the overloaded symbol @code{String::after}. |
| 3196 | We choose three particular definitions of that function name: |
| 3197 | |
| 3198 | @c FIXME! This is likely to change to show arg type lists, at least |
| 3199 | @smallexample |
| 3200 | @group |
| 3201 | (@value{GDBP}) b String::after |
| 3202 | [0] cancel |
| 3203 | [1] all |
| 3204 | [2] file:String.cc; line number:867 |
| 3205 | [3] file:String.cc; line number:860 |
| 3206 | [4] file:String.cc; line number:875 |
| 3207 | [5] file:String.cc; line number:853 |
| 3208 | [6] file:String.cc; line number:846 |
| 3209 | [7] file:String.cc; line number:735 |
| 3210 | > 2 4 6 |
| 3211 | Breakpoint 1 at 0xb26c: file String.cc, line 867. |
| 3212 | Breakpoint 2 at 0xb344: file String.cc, line 875. |
| 3213 | Breakpoint 3 at 0xafcc: file String.cc, line 846. |
| 3214 | Multiple breakpoints were set. |
| 3215 | Use the "delete" command to delete unwanted |
| 3216 | breakpoints. |
| 3217 | (@value{GDBP}) |
| 3218 | @end group |
| 3219 | @end smallexample |
| 3220 | |
| 3221 | @c @ifclear BARETARGET |
| 3222 | @node Error in Breakpoints |
| 3223 | @subsection ``Cannot insert breakpoints'' |
| 3224 | @c |
| 3225 | @c FIXME!! 14/6/95 Is there a real example of this? Let's use it. |
| 3226 | @c |
| 3227 | Under some operating systems, breakpoints cannot be used in a program if |
| 3228 | any other process is running that program. In this situation, |
| 3229 | attempting to run or continue a program with a breakpoint causes |
| 3230 | @value{GDBN} to print an error message: |
| 3231 | |
| 3232 | @smallexample |
| 3233 | Cannot insert breakpoints. |
| 3234 | The same program may be running in another process. |
| 3235 | @end smallexample |
| 3236 | |
| 3237 | When this happens, you have three ways to proceed: |
| 3238 | |
| 3239 | @enumerate |
| 3240 | @item |
| 3241 | Remove or disable the breakpoints, then continue. |
| 3242 | |
| 3243 | @item |
| 3244 | Suspend @value{GDBN}, and copy the file containing your program to a new |
| 3245 | name. Resume @value{GDBN} and use the @code{exec-file} command to specify |
| 3246 | that @value{GDBN} should run your program under that name. |
| 3247 | Then start your program again. |
| 3248 | |
| 3249 | @item |
| 3250 | Relink your program so that the text segment is nonsharable, using the |
| 3251 | linker option @samp{-N}. The operating system limitation may not apply |
| 3252 | to nonsharable executables. |
| 3253 | @end enumerate |
| 3254 | @c @end ifclear |
| 3255 | |
| 3256 | A similar message can be printed if you request too many active |
| 3257 | hardware-assisted breakpoints and watchpoints: |
| 3258 | |
| 3259 | @c FIXME: the precise wording of this message may change; the relevant |
| 3260 | @c source change is not committed yet (Sep 3, 1999). |
| 3261 | @smallexample |
| 3262 | Stopped; cannot insert breakpoints. |
| 3263 | You may have requested too many hardware breakpoints and watchpoints. |
| 3264 | @end smallexample |
| 3265 | |
| 3266 | @noindent |
| 3267 | This message is printed when you attempt to resume the program, since |
| 3268 | only then @value{GDBN} knows exactly how many hardware breakpoints and |
| 3269 | watchpoints it needs to insert. |
| 3270 | |
| 3271 | When this message is printed, you need to disable or remove some of the |
| 3272 | hardware-assisted breakpoints and watchpoints, and then continue. |
| 3273 | |
| 3274 | |
| 3275 | @node Continuing and Stepping |
| 3276 | @section Continuing and stepping |
| 3277 | |
| 3278 | @cindex stepping |
| 3279 | @cindex continuing |
| 3280 | @cindex resuming execution |
| 3281 | @dfn{Continuing} means resuming program execution until your program |
| 3282 | completes normally. In contrast, @dfn{stepping} means executing just |
| 3283 | one more ``step'' of your program, where ``step'' may mean either one |
| 3284 | line of source code, or one machine instruction (depending on what |
| 3285 | particular command you use). Either when continuing or when stepping, |
| 3286 | your program may stop even sooner, due to a breakpoint or a signal. (If |
| 3287 | it stops due to a signal, you may want to use @code{handle}, or use |
| 3288 | @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.) |
| 3289 | |
| 3290 | @table @code |
| 3291 | @kindex continue |
| 3292 | @kindex c @r{(@code{continue})} |
| 3293 | @kindex fg @r{(resume foreground execution)} |
| 3294 | @item continue @r{[}@var{ignore-count}@r{]} |
| 3295 | @itemx c @r{[}@var{ignore-count}@r{]} |
| 3296 | @itemx fg @r{[}@var{ignore-count}@r{]} |
| 3297 | Resume program execution, at the address where your program last stopped; |
| 3298 | any breakpoints set at that address are bypassed. The optional argument |
| 3299 | @var{ignore-count} allows you to specify a further number of times to |
| 3300 | ignore a breakpoint at this location; its effect is like that of |
| 3301 | @code{ignore} (@pxref{Conditions, ,Break conditions}). |
| 3302 | |
| 3303 | The argument @var{ignore-count} is meaningful only when your program |
| 3304 | stopped due to a breakpoint. At other times, the argument to |
| 3305 | @code{continue} is ignored. |
| 3306 | |
| 3307 | The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the |
| 3308 | debugged program is deemed to be the foreground program) are provided |
| 3309 | purely for convenience, and have exactly the same behavior as |
| 3310 | @code{continue}. |
| 3311 | @end table |
| 3312 | |
| 3313 | To resume execution at a different place, you can use @code{return} |
| 3314 | (@pxref{Returning, ,Returning from a function}) to go back to the |
| 3315 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a |
| 3316 | different address}) to go to an arbitrary location in your program. |
| 3317 | |
| 3318 | A typical technique for using stepping is to set a breakpoint |
| 3319 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and catchpoints}) at the |
| 3320 | beginning of the function or the section of your program where a problem |
| 3321 | is believed to lie, run your program until it stops at that breakpoint, |
| 3322 | and then step through the suspect area, examining the variables that are |
| 3323 | interesting, until you see the problem happen. |
| 3324 | |
| 3325 | @table @code |
| 3326 | @kindex step |
| 3327 | @kindex s @r{(@code{step})} |
| 3328 | @item step |
| 3329 | Continue running your program until control reaches a different source |
| 3330 | line, then stop it and return control to @value{GDBN}. This command is |
| 3331 | abbreviated @code{s}. |
| 3332 | |
| 3333 | @quotation |
| 3334 | @c "without debugging information" is imprecise; actually "without line |
| 3335 | @c numbers in the debugging information". (gcc -g1 has debugging info but |
| 3336 | @c not line numbers). But it seems complex to try to make that |
| 3337 | @c distinction here. |
| 3338 | @emph{Warning:} If you use the @code{step} command while control is |
| 3339 | within a function that was compiled without debugging information, |
| 3340 | execution proceeds until control reaches a function that does have |
| 3341 | debugging information. Likewise, it will not step into a function which |
| 3342 | is compiled without debugging information. To step through functions |
| 3343 | without debugging information, use the @code{stepi} command, described |
| 3344 | below. |
| 3345 | @end quotation |
| 3346 | |
| 3347 | The @code{step} command only stops at the first instruction of a source |
| 3348 | line. This prevents the multiple stops that could otherwise occur in |
| 3349 | @code{switch} statements, @code{for} loops, etc. @code{step} continues |
| 3350 | to stop if a function that has debugging information is called within |
| 3351 | the line. In other words, @code{step} @emph{steps inside} any functions |
| 3352 | called within the line. |
| 3353 | |
| 3354 | Also, the @code{step} command only enters a function if there is line |
| 3355 | number information for the function. Otherwise it acts like the |
| 3356 | @code{next} command. This avoids problems when using @code{cc -gl} |
| 3357 | on MIPS machines. Previously, @code{step} entered subroutines if there |
| 3358 | was any debugging information about the routine. |
| 3359 | |
| 3360 | @item step @var{count} |
| 3361 | Continue running as in @code{step}, but do so @var{count} times. If a |
| 3362 | breakpoint is reached, or a signal not related to stepping occurs before |
| 3363 | @var{count} steps, stepping stops right away. |
| 3364 | |
| 3365 | @kindex next |
| 3366 | @kindex n @r{(@code{next})} |
| 3367 | @item next @r{[}@var{count}@r{]} |
| 3368 | Continue to the next source line in the current (innermost) stack frame. |
| 3369 | This is similar to @code{step}, but function calls that appear within |
| 3370 | the line of code are executed without stopping. Execution stops when |
| 3371 | control reaches a different line of code at the original stack level |
| 3372 | that was executing when you gave the @code{next} command. This command |
| 3373 | is abbreviated @code{n}. |
| 3374 | |
| 3375 | An argument @var{count} is a repeat count, as for @code{step}. |
| 3376 | |
| 3377 | |
| 3378 | @c FIX ME!! Do we delete this, or is there a way it fits in with |
| 3379 | @c the following paragraph? --- Vctoria |
| 3380 | @c |
| 3381 | @c @code{next} within a function that lacks debugging information acts like |
| 3382 | @c @code{step}, but any function calls appearing within the code of the |
| 3383 | @c function are executed without stopping. |
| 3384 | |
| 3385 | The @code{next} command only stops at the first instruction of a |
| 3386 | source line. This prevents multiple stops that could otherwise occur in |
| 3387 | @code{switch} statements, @code{for} loops, etc. |
| 3388 | |
| 3389 | @kindex set step-mode |
| 3390 | @item set step-mode |
| 3391 | @cindex functions without line info, and stepping |
| 3392 | @cindex stepping into functions with no line info |
| 3393 | @itemx set step-mode on |
| 3394 | The @code{set step-mode on} command causes the @code{step} command to |
| 3395 | stop at the first instruction of a function which contains no debug line |
| 3396 | information rather than stepping over it. |
| 3397 | |
| 3398 | This is useful in cases where you may be interested in inspecting the |
| 3399 | machine instructions of a function which has no symbolic info and do not |
| 3400 | want @value{GDBN} to automatically skip over this function. |
| 3401 | |
| 3402 | @item set step-mode off |
| 3403 | Causes the @code{step} command to step over any functions which contains no |
| 3404 | debug information. This is the default. |
| 3405 | |
| 3406 | @kindex finish |
| 3407 | @item finish |
| 3408 | Continue running until just after function in the selected stack frame |
| 3409 | returns. Print the returned value (if any). |
| 3410 | |
| 3411 | Contrast this with the @code{return} command (@pxref{Returning, |
| 3412 | ,Returning from a function}). |
| 3413 | |
| 3414 | @kindex until |
| 3415 | @kindex u @r{(@code{until})} |
| 3416 | @item until |
| 3417 | @itemx u |
| 3418 | Continue running until a source line past the current line, in the |
| 3419 | current stack frame, is reached. This command is used to avoid single |
| 3420 | stepping through a loop more than once. It is like the @code{next} |
| 3421 | command, except that when @code{until} encounters a jump, it |
| 3422 | automatically continues execution until the program counter is greater |
| 3423 | than the address of the jump. |
| 3424 | |
| 3425 | This means that when you reach the end of a loop after single stepping |
| 3426 | though it, @code{until} makes your program continue execution until it |
| 3427 | exits the loop. In contrast, a @code{next} command at the end of a loop |
| 3428 | simply steps back to the beginning of the loop, which forces you to step |
| 3429 | through the next iteration. |
| 3430 | |
| 3431 | @code{until} always stops your program if it attempts to exit the current |
| 3432 | stack frame. |
| 3433 | |
| 3434 | @code{until} may produce somewhat counterintuitive results if the order |
| 3435 | of machine code does not match the order of the source lines. For |
| 3436 | example, in the following excerpt from a debugging session, the @code{f} |
| 3437 | (@code{frame}) command shows that execution is stopped at line |
| 3438 | @code{206}; yet when we use @code{until}, we get to line @code{195}: |
| 3439 | |
| 3440 | @smallexample |
| 3441 | (@value{GDBP}) f |
| 3442 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 |
| 3443 | 206 expand_input(); |
| 3444 | (@value{GDBP}) until |
| 3445 | 195 for ( ; argc > 0; NEXTARG) @{ |
| 3446 | @end smallexample |
| 3447 | |
| 3448 | This happened because, for execution efficiency, the compiler had |
| 3449 | generated code for the loop closure test at the end, rather than the |
| 3450 | start, of the loop---even though the test in a C @code{for}-loop is |
| 3451 | written before the body of the loop. The @code{until} command appeared |
| 3452 | to step back to the beginning of the loop when it advanced to this |
| 3453 | expression; however, it has not really gone to an earlier |
| 3454 | statement---not in terms of the actual machine code. |
| 3455 | |
| 3456 | @code{until} with no argument works by means of single |
| 3457 | instruction stepping, and hence is slower than @code{until} with an |
| 3458 | argument. |
| 3459 | |
| 3460 | @item until @var{location} |
| 3461 | @itemx u @var{location} |
| 3462 | Continue running your program until either the specified location is |
| 3463 | reached, or the current stack frame returns. @var{location} is any of |
| 3464 | the forms of argument acceptable to @code{break} (@pxref{Set Breaks, |
| 3465 | ,Setting breakpoints}). This form of the command uses breakpoints, |
| 3466 | and hence is quicker than @code{until} without an argument. |
| 3467 | |
| 3468 | @kindex stepi |
| 3469 | @kindex si @r{(@code{stepi})} |
| 3470 | @item stepi |
| 3471 | @itemx stepi @var{arg} |
| 3472 | @itemx si |
| 3473 | Execute one machine instruction, then stop and return to the debugger. |
| 3474 | |
| 3475 | It is often useful to do @samp{display/i $pc} when stepping by machine |
| 3476 | instructions. This makes @value{GDBN} automatically display the next |
| 3477 | instruction to be executed, each time your program stops. @xref{Auto |
| 3478 | Display,, Automatic display}. |
| 3479 | |
| 3480 | An argument is a repeat count, as in @code{step}. |
| 3481 | |
| 3482 | @need 750 |
| 3483 | @kindex nexti |
| 3484 | @kindex ni @r{(@code{nexti})} |
| 3485 | @item nexti |
| 3486 | @itemx nexti @var{arg} |
| 3487 | @itemx ni |
| 3488 | Execute one machine instruction, but if it is a function call, |
| 3489 | proceed until the function returns. |
| 3490 | |
| 3491 | An argument is a repeat count, as in @code{next}. |
| 3492 | @end table |
| 3493 | |
| 3494 | @node Signals |
| 3495 | @section Signals |
| 3496 | @cindex signals |
| 3497 | |
| 3498 | A signal is an asynchronous event that can happen in a program. The |
| 3499 | operating system defines the possible kinds of signals, and gives each |
| 3500 | kind a name and a number. For example, in Unix @code{SIGINT} is the |
| 3501 | signal a program gets when you type an interrupt character (often @kbd{C-c}); |
| 3502 | @code{SIGSEGV} is the signal a program gets from referencing a place in |
| 3503 | memory far away from all the areas in use; @code{SIGALRM} occurs when |
| 3504 | the alarm clock timer goes off (which happens only if your program has |
| 3505 | requested an alarm). |
| 3506 | |
| 3507 | @cindex fatal signals |
| 3508 | Some signals, including @code{SIGALRM}, are a normal part of the |
| 3509 | functioning of your program. Others, such as @code{SIGSEGV}, indicate |
| 3510 | errors; these signals are @dfn{fatal} (they kill your program immediately) if the |
| 3511 | program has not specified in advance some other way to handle the signal. |
| 3512 | @code{SIGINT} does not indicate an error in your program, but it is normally |
| 3513 | fatal so it can carry out the purpose of the interrupt: to kill the program. |
| 3514 | |
| 3515 | @value{GDBN} has the ability to detect any occurrence of a signal in your |
| 3516 | program. You can tell @value{GDBN} in advance what to do for each kind of |
| 3517 | signal. |
| 3518 | |
| 3519 | @cindex handling signals |
| 3520 | Normally, @value{GDBN} is set up to let the non-erroneous signals like |
| 3521 | @code{SIGALRM} be silently passed to your program |
| 3522 | (so as not to interfere with their role in the program's functioning) |
| 3523 | but to stop your program immediately whenever an error signal happens. |
| 3524 | You can change these settings with the @code{handle} command. |
| 3525 | |
| 3526 | @table @code |
| 3527 | @kindex info signals |
| 3528 | @item info signals |
| 3529 | @itemx info handle |
| 3530 | Print a table of all the kinds of signals and how @value{GDBN} has been told to |
| 3531 | handle each one. You can use this to see the signal numbers of all |
| 3532 | the defined types of signals. |
| 3533 | |
| 3534 | @code{info handle} is an alias for @code{info signals}. |
| 3535 | |
| 3536 | @kindex handle |
| 3537 | @item handle @var{signal} @var{keywords}@dots{} |
| 3538 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} |
| 3539 | can be the number of a signal or its name (with or without the |
| 3540 | @samp{SIG} at the beginning); a list of signal numbers of the form |
| 3541 | @samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the |
| 3542 | known signals. The @var{keywords} say what change to make. |
| 3543 | @end table |
| 3544 | |
| 3545 | @c @group |
| 3546 | The keywords allowed by the @code{handle} command can be abbreviated. |
| 3547 | Their full names are: |
| 3548 | |
| 3549 | @table @code |
| 3550 | @item nostop |
| 3551 | @value{GDBN} should not stop your program when this signal happens. It may |
| 3552 | still print a message telling you that the signal has come in. |
| 3553 | |
| 3554 | @item stop |
| 3555 | @value{GDBN} should stop your program when this signal happens. This implies |
| 3556 | the @code{print} keyword as well. |
| 3557 | |
| 3558 | @item print |
| 3559 | @value{GDBN} should print a message when this signal happens. |
| 3560 | |
| 3561 | @item noprint |
| 3562 | @value{GDBN} should not mention the occurrence of the signal at all. This |
| 3563 | implies the @code{nostop} keyword as well. |
| 3564 | |
| 3565 | @item pass |
| 3566 | @itemx noignore |
| 3567 | @value{GDBN} should allow your program to see this signal; your program |
| 3568 | can handle the signal, or else it may terminate if the signal is fatal |
| 3569 | and not handled. @code{pass} and @code{noignore} are synonyms. |
| 3570 | |
| 3571 | @item nopass |
| 3572 | @itemx ignore |
| 3573 | @value{GDBN} should not allow your program to see this signal. |
| 3574 | @code{nopass} and @code{ignore} are synonyms. |
| 3575 | @end table |
| 3576 | @c @end group |
| 3577 | |
| 3578 | When a signal stops your program, the signal is not visible to the |
| 3579 | program until you |
| 3580 | continue. Your program sees the signal then, if @code{pass} is in |
| 3581 | effect for the signal in question @emph{at that time}. In other words, |
| 3582 | after @value{GDBN} reports a signal, you can use the @code{handle} |
| 3583 | command with @code{pass} or @code{nopass} to control whether your |
| 3584 | program sees that signal when you continue. |
| 3585 | |
| 3586 | The default is set to @code{nostop}, @code{noprint}, @code{pass} for |
| 3587 | non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and |
| 3588 | @code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the |
| 3589 | erroneous signals. |
| 3590 | |
| 3591 | You can also use the @code{signal} command to prevent your program from |
| 3592 | seeing a signal, or cause it to see a signal it normally would not see, |
| 3593 | or to give it any signal at any time. For example, if your program stopped |
| 3594 | due to some sort of memory reference error, you might store correct |
| 3595 | values into the erroneous variables and continue, hoping to see more |
| 3596 | execution; but your program would probably terminate immediately as |
| 3597 | a result of the fatal signal once it saw the signal. To prevent this, |
| 3598 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your |
| 3599 | program a signal}. |
| 3600 | |
| 3601 | @node Thread Stops |
| 3602 | @section Stopping and starting multi-thread programs |
| 3603 | |
| 3604 | When your program has multiple threads (@pxref{Threads,, Debugging |
| 3605 | programs with multiple threads}), you can choose whether to set |
| 3606 | breakpoints on all threads, or on a particular thread. |
| 3607 | |
| 3608 | @table @code |
| 3609 | @cindex breakpoints and threads |
| 3610 | @cindex thread breakpoints |
| 3611 | @kindex break @dots{} thread @var{threadno} |
| 3612 | @item break @var{linespec} thread @var{threadno} |
| 3613 | @itemx break @var{linespec} thread @var{threadno} if @dots{} |
| 3614 | @var{linespec} specifies source lines; there are several ways of |
| 3615 | writing them, but the effect is always to specify some source line. |
| 3616 | |
| 3617 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command |
| 3618 | to specify that you only want @value{GDBN} to stop the program when a |
| 3619 | particular thread reaches this breakpoint. @var{threadno} is one of the |
| 3620 | numeric thread identifiers assigned by @value{GDBN}, shown in the first |
| 3621 | column of the @samp{info threads} display. |
| 3622 | |
| 3623 | If you do not specify @samp{thread @var{threadno}} when you set a |
| 3624 | breakpoint, the breakpoint applies to @emph{all} threads of your |
| 3625 | program. |
| 3626 | |
| 3627 | You can use the @code{thread} qualifier on conditional breakpoints as |
| 3628 | well; in this case, place @samp{thread @var{threadno}} before the |
| 3629 | breakpoint condition, like this: |
| 3630 | |
| 3631 | @smallexample |
| 3632 | (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim |
| 3633 | @end smallexample |
| 3634 | |
| 3635 | @end table |
| 3636 | |
| 3637 | @cindex stopped threads |
| 3638 | @cindex threads, stopped |
| 3639 | Whenever your program stops under @value{GDBN} for any reason, |
| 3640 | @emph{all} threads of execution stop, not just the current thread. This |
| 3641 | allows you to examine the overall state of the program, including |
| 3642 | switching between threads, without worrying that things may change |
| 3643 | underfoot. |
| 3644 | |
| 3645 | @cindex continuing threads |
| 3646 | @cindex threads, continuing |
| 3647 | Conversely, whenever you restart the program, @emph{all} threads start |
| 3648 | executing. @emph{This is true even when single-stepping} with commands |
| 3649 | like @code{step} or @code{next}. |
| 3650 | |
| 3651 | In particular, @value{GDBN} cannot single-step all threads in lockstep. |
| 3652 | Since thread scheduling is up to your debugging target's operating |
| 3653 | system (not controlled by @value{GDBN}), other threads may |
| 3654 | execute more than one statement while the current thread completes a |
| 3655 | single step. Moreover, in general other threads stop in the middle of a |
| 3656 | statement, rather than at a clean statement boundary, when the program |
| 3657 | stops. |
| 3658 | |
| 3659 | You might even find your program stopped in another thread after |
| 3660 | continuing or even single-stepping. This happens whenever some other |
| 3661 | thread runs into a breakpoint, a signal, or an exception before the |
| 3662 | first thread completes whatever you requested. |
| 3663 | |
| 3664 | On some OSes, you can lock the OS scheduler and thus allow only a single |
| 3665 | thread to run. |
| 3666 | |
| 3667 | @table @code |
| 3668 | @item set scheduler-locking @var{mode} |
| 3669 | Set the scheduler locking mode. If it is @code{off}, then there is no |
| 3670 | locking and any thread may run at any time. If @code{on}, then only the |
| 3671 | current thread may run when the inferior is resumed. The @code{step} |
| 3672 | mode optimizes for single-stepping. It stops other threads from |
| 3673 | ``seizing the prompt'' by preempting the current thread while you are |
| 3674 | stepping. Other threads will only rarely (or never) get a chance to run |
| 3675 | when you step. They are more likely to run when you @samp{next} over a |
| 3676 | function call, and they are completely free to run when you use commands |
| 3677 | like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another |
| 3678 | thread hits a breakpoint during its timeslice, they will never steal the |
| 3679 | @value{GDBN} prompt away from the thread that you are debugging. |
| 3680 | |
| 3681 | @item show scheduler-locking |
| 3682 | Display the current scheduler locking mode. |
| 3683 | @end table |
| 3684 | |
| 3685 | |
| 3686 | @node Stack |
| 3687 | @chapter Examining the Stack |
| 3688 | |
| 3689 | When your program has stopped, the first thing you need to know is where it |
| 3690 | stopped and how it got there. |
| 3691 | |
| 3692 | @cindex call stack |
| 3693 | Each time your program performs a function call, information about the call |
| 3694 | is generated. |
| 3695 | That information includes the location of the call in your program, |
| 3696 | the arguments of the call, |
| 3697 | and the local variables of the function being called. |
| 3698 | The information is saved in a block of data called a @dfn{stack frame}. |
| 3699 | The stack frames are allocated in a region of memory called the @dfn{call |
| 3700 | stack}. |
| 3701 | |
| 3702 | When your program stops, the @value{GDBN} commands for examining the |
| 3703 | stack allow you to see all of this information. |
| 3704 | |
| 3705 | @cindex selected frame |
| 3706 | One of the stack frames is @dfn{selected} by @value{GDBN} and many |
| 3707 | @value{GDBN} commands refer implicitly to the selected frame. In |
| 3708 | particular, whenever you ask @value{GDBN} for the value of a variable in |
| 3709 | your program, the value is found in the selected frame. There are |
| 3710 | special @value{GDBN} commands to select whichever frame you are |
| 3711 | interested in. @xref{Selection, ,Selecting a frame}. |
| 3712 | |
| 3713 | When your program stops, @value{GDBN} automatically selects the |
| 3714 | currently executing frame and describes it briefly, similar to the |
| 3715 | @code{frame} command (@pxref{Frame Info, ,Information about a frame}). |
| 3716 | |
| 3717 | @menu |
| 3718 | * Frames:: Stack frames |
| 3719 | * Backtrace:: Backtraces |
| 3720 | * Selection:: Selecting a frame |
| 3721 | * Frame Info:: Information on a frame |
| 3722 | |
| 3723 | @end menu |
| 3724 | |
| 3725 | @node Frames |
| 3726 | @section Stack frames |
| 3727 | |
| 3728 | @cindex frame, definition |
| 3729 | @cindex stack frame |
| 3730 | The call stack is divided up into contiguous pieces called @dfn{stack |
| 3731 | frames}, or @dfn{frames} for short; each frame is the data associated |
| 3732 | with one call to one function. The frame contains the arguments given |
| 3733 | to the function, the function's local variables, and the address at |
| 3734 | which the function is executing. |
| 3735 | |
| 3736 | @cindex initial frame |
| 3737 | @cindex outermost frame |
| 3738 | @cindex innermost frame |
| 3739 | When your program is started, the stack has only one frame, that of the |
| 3740 | function @code{main}. This is called the @dfn{initial} frame or the |
| 3741 | @dfn{outermost} frame. Each time a function is called, a new frame is |
| 3742 | made. Each time a function returns, the frame for that function invocation |
| 3743 | is eliminated. If a function is recursive, there can be many frames for |
| 3744 | the same function. The frame for the function in which execution is |
| 3745 | actually occurring is called the @dfn{innermost} frame. This is the most |
| 3746 | recently created of all the stack frames that still exist. |
| 3747 | |
| 3748 | @cindex frame pointer |
| 3749 | Inside your program, stack frames are identified by their addresses. A |
| 3750 | stack frame consists of many bytes, each of which has its own address; each |
| 3751 | kind of computer has a convention for choosing one byte whose |
| 3752 | address serves as the address of the frame. Usually this address is kept |
| 3753 | in a register called the @dfn{frame pointer register} while execution is |
| 3754 | going on in that frame. |
| 3755 | |
| 3756 | @cindex frame number |
| 3757 | @value{GDBN} assigns numbers to all existing stack frames, starting with |
| 3758 | zero for the innermost frame, one for the frame that called it, |
| 3759 | and so on upward. These numbers do not really exist in your program; |
| 3760 | they are assigned by @value{GDBN} to give you a way of designating stack |
| 3761 | frames in @value{GDBN} commands. |
| 3762 | |
| 3763 | @c The -fomit-frame-pointer below perennially causes hbox overflow |
| 3764 | @c underflow problems. |
| 3765 | @cindex frameless execution |
| 3766 | Some compilers provide a way to compile functions so that they operate |
| 3767 | without stack frames. (For example, the @value{GCC} option |
| 3768 | @smallexample |
| 3769 | @samp{-fomit-frame-pointer} |
| 3770 | @end smallexample |
| 3771 | generates functions without a frame.) |
| 3772 | This is occasionally done with heavily used library functions to save |
| 3773 | the frame setup time. @value{GDBN} has limited facilities for dealing |
| 3774 | with these function invocations. If the innermost function invocation |
| 3775 | has no stack frame, @value{GDBN} nevertheless regards it as though |
| 3776 | it had a separate frame, which is numbered zero as usual, allowing |
| 3777 | correct tracing of the function call chain. However, @value{GDBN} has |
| 3778 | no provision for frameless functions elsewhere in the stack. |
| 3779 | |
| 3780 | @table @code |
| 3781 | @kindex frame@r{, command} |
| 3782 | @cindex current stack frame |
| 3783 | @item frame @var{args} |
| 3784 | The @code{frame} command allows you to move from one stack frame to another, |
| 3785 | and to print the stack frame you select. @var{args} may be either the |
| 3786 | address of the frame or the stack frame number. Without an argument, |
| 3787 | @code{frame} prints the current stack frame. |
| 3788 | |
| 3789 | @kindex select-frame |
| 3790 | @cindex selecting frame silently |
| 3791 | @item select-frame |
| 3792 | The @code{select-frame} command allows you to move from one stack frame |
| 3793 | to another without printing the frame. This is the silent version of |
| 3794 | @code{frame}. |
| 3795 | @end table |
| 3796 | |
| 3797 | @node Backtrace |
| 3798 | @section Backtraces |
| 3799 | |
| 3800 | @cindex backtraces |
| 3801 | @cindex tracebacks |
| 3802 | @cindex stack traces |
| 3803 | A backtrace is a summary of how your program got where it is. It shows one |
| 3804 | line per frame, for many frames, starting with the currently executing |
| 3805 | frame (frame zero), followed by its caller (frame one), and on up the |
| 3806 | stack. |
| 3807 | |
| 3808 | @table @code |
| 3809 | @kindex backtrace |
| 3810 | @kindex bt @r{(@code{backtrace})} |
| 3811 | @item backtrace |
| 3812 | @itemx bt |
| 3813 | Print a backtrace of the entire stack: one line per frame for all |
| 3814 | frames in the stack. |
| 3815 | |
| 3816 | You can stop the backtrace at any time by typing the system interrupt |
| 3817 | character, normally @kbd{C-c}. |
| 3818 | |
| 3819 | @item backtrace @var{n} |
| 3820 | @itemx bt @var{n} |
| 3821 | Similar, but print only the innermost @var{n} frames. |
| 3822 | |
| 3823 | @item backtrace -@var{n} |
| 3824 | @itemx bt -@var{n} |
| 3825 | Similar, but print only the outermost @var{n} frames. |
| 3826 | @end table |
| 3827 | |
| 3828 | @kindex where |
| 3829 | @kindex info stack |
| 3830 | @kindex info s @r{(@code{info stack})} |
| 3831 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) |
| 3832 | are additional aliases for @code{backtrace}. |
| 3833 | |
| 3834 | Each line in the backtrace shows the frame number and the function name. |
| 3835 | The program counter value is also shown---unless you use @code{set |
| 3836 | print address off}. The backtrace also shows the source file name and |
| 3837 | line number, as well as the arguments to the function. The program |
| 3838 | counter value is omitted if it is at the beginning of the code for that |
| 3839 | line number. |
| 3840 | |
| 3841 | Here is an example of a backtrace. It was made with the command |
| 3842 | @samp{bt 3}, so it shows the innermost three frames. |
| 3843 | |
| 3844 | @smallexample |
| 3845 | @group |
| 3846 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
| 3847 | at builtin.c:993 |
| 3848 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 |
| 3849 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) |
| 3850 | at macro.c:71 |
| 3851 | (More stack frames follow...) |
| 3852 | @end group |
| 3853 | @end smallexample |
| 3854 | |
| 3855 | @noindent |
| 3856 | The display for frame zero does not begin with a program counter |
| 3857 | value, indicating that your program has stopped at the beginning of the |
| 3858 | code for line @code{993} of @code{builtin.c}. |
| 3859 | |
| 3860 | Most programs have a standard entry point---a place where system libraries |
| 3861 | and startup code transition into user code. For C this is @code{main}. |
| 3862 | When @value{GDBN} finds the entry function in a backtrace it will terminate |
| 3863 | the backtrace, to avoid tracing into highly system-specific (and generally |
| 3864 | uninteresting) code. If you need to examine the startup code, then you can |
| 3865 | change this behavior. |
| 3866 | |
| 3867 | @table @code |
| 3868 | @item set backtrace-below-main off |
| 3869 | Backtraces will stop when they encounter the user entry point. This is the |
| 3870 | default. |
| 3871 | |
| 3872 | @item set backtrace-below-main |
| 3873 | @itemx set backtrace-below-main on |
| 3874 | Backtraces will continue past the user entry point to the top of the stack. |
| 3875 | |
| 3876 | @item show backtrace-below-main |
| 3877 | Display the current backtrace policy. |
| 3878 | @end table |
| 3879 | |
| 3880 | @node Selection |
| 3881 | @section Selecting a frame |
| 3882 | |
| 3883 | Most commands for examining the stack and other data in your program work on |
| 3884 | whichever stack frame is selected at the moment. Here are the commands for |
| 3885 | selecting a stack frame; all of them finish by printing a brief description |
| 3886 | of the stack frame just selected. |
| 3887 | |
| 3888 | @table @code |
| 3889 | @kindex frame@r{, selecting} |
| 3890 | @kindex f @r{(@code{frame})} |
| 3891 | @item frame @var{n} |
| 3892 | @itemx f @var{n} |
| 3893 | Select frame number @var{n}. Recall that frame zero is the innermost |
| 3894 | (currently executing) frame, frame one is the frame that called the |
| 3895 | innermost one, and so on. The highest-numbered frame is the one for |
| 3896 | @code{main}. |
| 3897 | |
| 3898 | @item frame @var{addr} |
| 3899 | @itemx f @var{addr} |
| 3900 | Select the frame at address @var{addr}. This is useful mainly if the |
| 3901 | chaining of stack frames has been damaged by a bug, making it |
| 3902 | impossible for @value{GDBN} to assign numbers properly to all frames. In |
| 3903 | addition, this can be useful when your program has multiple stacks and |
| 3904 | switches between them. |
| 3905 | |
| 3906 | On the SPARC architecture, @code{frame} needs two addresses to |
| 3907 | select an arbitrary frame: a frame pointer and a stack pointer. |
| 3908 | |
| 3909 | On the MIPS and Alpha architecture, it needs two addresses: a stack |
| 3910 | pointer and a program counter. |
| 3911 | |
| 3912 | On the 29k architecture, it needs three addresses: a register stack |
| 3913 | pointer, a program counter, and a memory stack pointer. |
| 3914 | @c note to future updaters: this is conditioned on a flag |
| 3915 | @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date |
| 3916 | @c as of 27 Jan 1994. |
| 3917 | |
| 3918 | @kindex up |
| 3919 | @item up @var{n} |
| 3920 | Move @var{n} frames up the stack. For positive numbers @var{n}, this |
| 3921 | advances toward the outermost frame, to higher frame numbers, to frames |
| 3922 | that have existed longer. @var{n} defaults to one. |
| 3923 | |
| 3924 | @kindex down |
| 3925 | @kindex do @r{(@code{down})} |
| 3926 | @item down @var{n} |
| 3927 | Move @var{n} frames down the stack. For positive numbers @var{n}, this |
| 3928 | advances toward the innermost frame, to lower frame numbers, to frames |
| 3929 | that were created more recently. @var{n} defaults to one. You may |
| 3930 | abbreviate @code{down} as @code{do}. |
| 3931 | @end table |
| 3932 | |
| 3933 | All of these commands end by printing two lines of output describing the |
| 3934 | frame. The first line shows the frame number, the function name, the |
| 3935 | arguments, and the source file and line number of execution in that |
| 3936 | frame. The second line shows the text of that source line. |
| 3937 | |
| 3938 | @need 1000 |
| 3939 | For example: |
| 3940 | |
| 3941 | @smallexample |
| 3942 | @group |
| 3943 | (@value{GDBP}) up |
| 3944 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) |
| 3945 | at env.c:10 |
| 3946 | 10 read_input_file (argv[i]); |
| 3947 | @end group |
| 3948 | @end smallexample |
| 3949 | |
| 3950 | After such a printout, the @code{list} command with no arguments |
| 3951 | prints ten lines centered on the point of execution in the frame. |
| 3952 | You can also edit the program at the point of execution with your favorite |
| 3953 | editing program by typing @code{edit}. |
| 3954 | @xref{List, ,Printing source lines}, |
| 3955 | for details. |
| 3956 | |
| 3957 | @table @code |
| 3958 | @kindex down-silently |
| 3959 | @kindex up-silently |
| 3960 | @item up-silently @var{n} |
| 3961 | @itemx down-silently @var{n} |
| 3962 | These two commands are variants of @code{up} and @code{down}, |
| 3963 | respectively; they differ in that they do their work silently, without |
| 3964 | causing display of the new frame. They are intended primarily for use |
| 3965 | in @value{GDBN} command scripts, where the output might be unnecessary and |
| 3966 | distracting. |
| 3967 | @end table |
| 3968 | |
| 3969 | @node Frame Info |
| 3970 | @section Information about a frame |
| 3971 | |
| 3972 | There are several other commands to print information about the selected |
| 3973 | stack frame. |
| 3974 | |
| 3975 | @table @code |
| 3976 | @item frame |
| 3977 | @itemx f |
| 3978 | When used without any argument, this command does not change which |
| 3979 | frame is selected, but prints a brief description of the currently |
| 3980 | selected stack frame. It can be abbreviated @code{f}. With an |
| 3981 | argument, this command is used to select a stack frame. |
| 3982 | @xref{Selection, ,Selecting a frame}. |
| 3983 | |
| 3984 | @kindex info frame |
| 3985 | @kindex info f @r{(@code{info frame})} |
| 3986 | @item info frame |
| 3987 | @itemx info f |
| 3988 | This command prints a verbose description of the selected stack frame, |
| 3989 | including: |
| 3990 | |
| 3991 | @itemize @bullet |
| 3992 | @item |
| 3993 | the address of the frame |
| 3994 | @item |
| 3995 | the address of the next frame down (called by this frame) |
| 3996 | @item |
| 3997 | the address of the next frame up (caller of this frame) |
| 3998 | @item |
| 3999 | the language in which the source code corresponding to this frame is written |
| 4000 | @item |
| 4001 | the address of the frame's arguments |
| 4002 | @item |
| 4003 | the address of the frame's local variables |
| 4004 | @item |
| 4005 | the program counter saved in it (the address of execution in the caller frame) |
| 4006 | @item |
| 4007 | which registers were saved in the frame |
| 4008 | @end itemize |
| 4009 | |
| 4010 | @noindent The verbose description is useful when |
| 4011 | something has gone wrong that has made the stack format fail to fit |
| 4012 | the usual conventions. |
| 4013 | |
| 4014 | @item info frame @var{addr} |
| 4015 | @itemx info f @var{addr} |
| 4016 | Print a verbose description of the frame at address @var{addr}, without |
| 4017 | selecting that frame. The selected frame remains unchanged by this |
| 4018 | command. This requires the same kind of address (more than one for some |
| 4019 | architectures) that you specify in the @code{frame} command. |
| 4020 | @xref{Selection, ,Selecting a frame}. |
| 4021 | |
| 4022 | @kindex info args |
| 4023 | @item info args |
| 4024 | Print the arguments of the selected frame, each on a separate line. |
| 4025 | |
| 4026 | @item info locals |
| 4027 | @kindex info locals |
| 4028 | Print the local variables of the selected frame, each on a separate |
| 4029 | line. These are all variables (declared either static or automatic) |
| 4030 | accessible at the point of execution of the selected frame. |
| 4031 | |
| 4032 | @kindex info catch |
| 4033 | @cindex catch exceptions, list active handlers |
| 4034 | @cindex exception handlers, how to list |
| 4035 | @item info catch |
| 4036 | Print a list of all the exception handlers that are active in the |
| 4037 | current stack frame at the current point of execution. To see other |
| 4038 | exception handlers, visit the associated frame (using the @code{up}, |
| 4039 | @code{down}, or @code{frame} commands); then type @code{info catch}. |
| 4040 | @xref{Set Catchpoints, , Setting catchpoints}. |
| 4041 | |
| 4042 | @end table |
| 4043 | |
| 4044 | |
| 4045 | @node Source |
| 4046 | @chapter Examining Source Files |
| 4047 | |
| 4048 | @value{GDBN} can print parts of your program's source, since the debugging |
| 4049 | information recorded in the program tells @value{GDBN} what source files were |
| 4050 | used to build it. When your program stops, @value{GDBN} spontaneously prints |
| 4051 | the line where it stopped. Likewise, when you select a stack frame |
| 4052 | (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where |
| 4053 | execution in that frame has stopped. You can print other portions of |
| 4054 | source files by explicit command. |
| 4055 | |
| 4056 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may |
| 4057 | prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using |
| 4058 | @value{GDBN} under @sc{gnu} Emacs}. |
| 4059 | |
| 4060 | @menu |
| 4061 | * List:: Printing source lines |
| 4062 | * Edit:: Editing source files |
| 4063 | * Search:: Searching source files |
| 4064 | * Source Path:: Specifying source directories |
| 4065 | * Machine Code:: Source and machine code |
| 4066 | @end menu |
| 4067 | |
| 4068 | @node List |
| 4069 | @section Printing source lines |
| 4070 | |
| 4071 | @kindex list |
| 4072 | @kindex l @r{(@code{list})} |
| 4073 | To print lines from a source file, use the @code{list} command |
| 4074 | (abbreviated @code{l}). By default, ten lines are printed. |
| 4075 | There are several ways to specify what part of the file you want to print. |
| 4076 | |
| 4077 | Here are the forms of the @code{list} command most commonly used: |
| 4078 | |
| 4079 | @table @code |
| 4080 | @item list @var{linenum} |
| 4081 | Print lines centered around line number @var{linenum} in the |
| 4082 | current source file. |
| 4083 | |
| 4084 | @item list @var{function} |
| 4085 | Print lines centered around the beginning of function |
| 4086 | @var{function}. |
| 4087 | |
| 4088 | @item list |
| 4089 | Print more lines. If the last lines printed were printed with a |
| 4090 | @code{list} command, this prints lines following the last lines |
| 4091 | printed; however, if the last line printed was a solitary line printed |
| 4092 | as part of displaying a stack frame (@pxref{Stack, ,Examining the |
| 4093 | Stack}), this prints lines centered around that line. |
| 4094 | |
| 4095 | @item list - |
| 4096 | Print lines just before the lines last printed. |
| 4097 | @end table |
| 4098 | |
| 4099 | By default, @value{GDBN} prints ten source lines with any of these forms of |
| 4100 | the @code{list} command. You can change this using @code{set listsize}: |
| 4101 | |
| 4102 | @table @code |
| 4103 | @kindex set listsize |
| 4104 | @item set listsize @var{count} |
| 4105 | Make the @code{list} command display @var{count} source lines (unless |
| 4106 | the @code{list} argument explicitly specifies some other number). |
| 4107 | |
| 4108 | @kindex show listsize |
| 4109 | @item show listsize |
| 4110 | Display the number of lines that @code{list} prints. |
| 4111 | @end table |
| 4112 | |
| 4113 | Repeating a @code{list} command with @key{RET} discards the argument, |
| 4114 | so it is equivalent to typing just @code{list}. This is more useful |
| 4115 | than listing the same lines again. An exception is made for an |
| 4116 | argument of @samp{-}; that argument is preserved in repetition so that |
| 4117 | each repetition moves up in the source file. |
| 4118 | |
| 4119 | @cindex linespec |
| 4120 | In general, the @code{list} command expects you to supply zero, one or two |
| 4121 | @dfn{linespecs}. Linespecs specify source lines; there are several ways |
| 4122 | of writing them, but the effect is always to specify some source line. |
| 4123 | Here is a complete description of the possible arguments for @code{list}: |
| 4124 | |
| 4125 | @table @code |
| 4126 | @item list @var{linespec} |
| 4127 | Print lines centered around the line specified by @var{linespec}. |
| 4128 | |
| 4129 | @item list @var{first},@var{last} |
| 4130 | Print lines from @var{first} to @var{last}. Both arguments are |
| 4131 | linespecs. |
| 4132 | |
| 4133 | @item list ,@var{last} |
| 4134 | Print lines ending with @var{last}. |
| 4135 | |
| 4136 | @item list @var{first}, |
| 4137 | Print lines starting with @var{first}. |
| 4138 | |
| 4139 | @item list + |
| 4140 | Print lines just after the lines last printed. |
| 4141 | |
| 4142 | @item list - |
| 4143 | Print lines just before the lines last printed. |
| 4144 | |
| 4145 | @item list |
| 4146 | As described in the preceding table. |
| 4147 | @end table |
| 4148 | |
| 4149 | Here are the ways of specifying a single source line---all the |
| 4150 | kinds of linespec. |
| 4151 | |
| 4152 | @table @code |
| 4153 | @item @var{number} |
| 4154 | Specifies line @var{number} of the current source file. |
| 4155 | When a @code{list} command has two linespecs, this refers to |
| 4156 | the same source file as the first linespec. |
| 4157 | |
| 4158 | @item +@var{offset} |
| 4159 | Specifies the line @var{offset} lines after the last line printed. |
| 4160 | When used as the second linespec in a @code{list} command that has |
| 4161 | two, this specifies the line @var{offset} lines down from the |
| 4162 | first linespec. |
| 4163 | |
| 4164 | @item -@var{offset} |
| 4165 | Specifies the line @var{offset} lines before the last line printed. |
| 4166 | |
| 4167 | @item @var{filename}:@var{number} |
| 4168 | Specifies line @var{number} in the source file @var{filename}. |
| 4169 | |
| 4170 | @item @var{function} |
| 4171 | Specifies the line that begins the body of the function @var{function}. |
| 4172 | For example: in C, this is the line with the open brace. |
| 4173 | |
| 4174 | @item @var{filename}:@var{function} |
| 4175 | Specifies the line of the open-brace that begins the body of the |
| 4176 | function @var{function} in the file @var{filename}. You only need the |
| 4177 | file name with a function name to avoid ambiguity when there are |
| 4178 | identically named functions in different source files. |
| 4179 | |
| 4180 | @item *@var{address} |
| 4181 | Specifies the line containing the program address @var{address}. |
| 4182 | @var{address} may be any expression. |
| 4183 | @end table |
| 4184 | |
| 4185 | @node Edit |
| 4186 | @section Editing source files |
| 4187 | @cindex editing source files |
| 4188 | |
| 4189 | @kindex edit |
| 4190 | @kindex e @r{(@code{edit})} |
| 4191 | To edit the lines in a source file, use the @code{edit} command. |
| 4192 | The editing program of your choice |
| 4193 | is invoked with the current line set to |
| 4194 | the active line in the program. |
| 4195 | Alternatively, there are several ways to specify what part of the file you |
| 4196 | want to print if you want to see other parts of the program. |
| 4197 | |
| 4198 | Here are the forms of the @code{edit} command most commonly used: |
| 4199 | |
| 4200 | @table @code |
| 4201 | @item edit |
| 4202 | Edit the current source file at the active line number in the program. |
| 4203 | |
| 4204 | @item edit @var{number} |
| 4205 | Edit the current source file with @var{number} as the active line number. |
| 4206 | |
| 4207 | @item edit @var{function} |
| 4208 | Edit the file containing @var{function} at the beginning of its definition. |
| 4209 | |
| 4210 | @item edit @var{filename}:@var{number} |
| 4211 | Specifies line @var{number} in the source file @var{filename}. |
| 4212 | |
| 4213 | @item edit @var{filename}:@var{function} |
| 4214 | Specifies the line that begins the body of the |
| 4215 | function @var{function} in the file @var{filename}. You only need the |
| 4216 | file name with a function name to avoid ambiguity when there are |
| 4217 | identically named functions in different source files. |
| 4218 | |
| 4219 | @item edit *@var{address} |
| 4220 | Specifies the line containing the program address @var{address}. |
| 4221 | @var{address} may be any expression. |
| 4222 | @end table |
| 4223 | |
| 4224 | @subsection Choosing your editor |
| 4225 | You can customize @value{GDBN} to use any editor you want |
| 4226 | @footnote{ |
| 4227 | The only restriction is that your editor (say @code{ex}), recognizes the |
| 4228 | following command-line syntax: |
| 4229 | @smallexample |
| 4230 | ex +@var{number} file |
| 4231 | @end smallexample |
| 4232 | The optional numeric value +@var{number} designates the active line in |
| 4233 | the file.}. By default, it is @value{EDITOR}, but you can change this |
| 4234 | by setting the environment variable @code{EDITOR} before using |
| 4235 | @value{GDBN}. For example, to configure @value{GDBN} to use the |
| 4236 | @code{vi} editor, you could use these commands with the @code{sh} shell: |
| 4237 | @smallexample |
| 4238 | EDITOR=/usr/bin/vi |
| 4239 | export EDITOR |
| 4240 | gdb ... |
| 4241 | @end smallexample |
| 4242 | or in the @code{csh} shell, |
| 4243 | @smallexample |
| 4244 | setenv EDITOR /usr/bin/vi |
| 4245 | gdb ... |
| 4246 | @end smallexample |
| 4247 | |
| 4248 | @node Search |
| 4249 | @section Searching source files |
| 4250 | @cindex searching |
| 4251 | @kindex reverse-search |
| 4252 | |
| 4253 | There are two commands for searching through the current source file for a |
| 4254 | regular expression. |
| 4255 | |
| 4256 | @table @code |
| 4257 | @kindex search |
| 4258 | @kindex forward-search |
| 4259 | @item forward-search @var{regexp} |
| 4260 | @itemx search @var{regexp} |
| 4261 | The command @samp{forward-search @var{regexp}} checks each line, |
| 4262 | starting with the one following the last line listed, for a match for |
| 4263 | @var{regexp}. It lists the line that is found. You can use the |
| 4264 | synonym @samp{search @var{regexp}} or abbreviate the command name as |
| 4265 | @code{fo}. |
| 4266 | |
| 4267 | @item reverse-search @var{regexp} |
| 4268 | The command @samp{reverse-search @var{regexp}} checks each line, starting |
| 4269 | with the one before the last line listed and going backward, for a match |
| 4270 | for @var{regexp}. It lists the line that is found. You can abbreviate |
| 4271 | this command as @code{rev}. |
| 4272 | @end table |
| 4273 | |
| 4274 | @node Source Path |
| 4275 | @section Specifying source directories |
| 4276 | |
| 4277 | @cindex source path |
| 4278 | @cindex directories for source files |
| 4279 | Executable programs sometimes do not record the directories of the source |
| 4280 | files from which they were compiled, just the names. Even when they do, |
| 4281 | the directories could be moved between the compilation and your debugging |
| 4282 | session. @value{GDBN} has a list of directories to search for source files; |
| 4283 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, |
| 4284 | it tries all the directories in the list, in the order they are present |
| 4285 | in the list, until it finds a file with the desired name. Note that |
| 4286 | the executable search path is @emph{not} used for this purpose. Neither is |
| 4287 | the current working directory, unless it happens to be in the source |
| 4288 | path. |
| 4289 | |
| 4290 | If @value{GDBN} cannot find a source file in the source path, and the |
| 4291 | object program records a directory, @value{GDBN} tries that directory |
| 4292 | too. If the source path is empty, and there is no record of the |
| 4293 | compilation directory, @value{GDBN} looks in the current directory as a |
| 4294 | last resort. |
| 4295 | |
| 4296 | Whenever you reset or rearrange the source path, @value{GDBN} clears out |
| 4297 | any information it has cached about where source files are found and where |
| 4298 | each line is in the file. |
| 4299 | |
| 4300 | @kindex directory |
| 4301 | @kindex dir |
| 4302 | When you start @value{GDBN}, its source path includes only @samp{cdir} |
| 4303 | and @samp{cwd}, in that order. |
| 4304 | To add other directories, use the @code{directory} command. |
| 4305 | |
| 4306 | @table @code |
| 4307 | @item directory @var{dirname} @dots{} |
| 4308 | @item dir @var{dirname} @dots{} |
| 4309 | Add directory @var{dirname} to the front of the source path. Several |
| 4310 | directory names may be given to this command, separated by @samp{:} |
| 4311 | (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as |
| 4312 | part of absolute file names) or |
| 4313 | whitespace. You may specify a directory that is already in the source |
| 4314 | path; this moves it forward, so @value{GDBN} searches it sooner. |
| 4315 | |
| 4316 | @kindex cdir |
| 4317 | @kindex cwd |
| 4318 | @vindex $cdir@r{, convenience variable} |
| 4319 | @vindex $cwdr@r{, convenience variable} |
| 4320 | @cindex compilation directory |
| 4321 | @cindex current directory |
| 4322 | @cindex working directory |
| 4323 | @cindex directory, current |
| 4324 | @cindex directory, compilation |
| 4325 | You can use the string @samp{$cdir} to refer to the compilation |
| 4326 | directory (if one is recorded), and @samp{$cwd} to refer to the current |
| 4327 | working directory. @samp{$cwd} is not the same as @samp{.}---the former |
| 4328 | tracks the current working directory as it changes during your @value{GDBN} |
| 4329 | session, while the latter is immediately expanded to the current |
| 4330 | directory at the time you add an entry to the source path. |
| 4331 | |
| 4332 | @item directory |
| 4333 | Reset the source path to empty again. This requires confirmation. |
| 4334 | |
| 4335 | @c RET-repeat for @code{directory} is explicitly disabled, but since |
| 4336 | @c repeating it would be a no-op we do not say that. (thanks to RMS) |
| 4337 | |
| 4338 | @item show directories |
| 4339 | @kindex show directories |
| 4340 | Print the source path: show which directories it contains. |
| 4341 | @end table |
| 4342 | |
| 4343 | If your source path is cluttered with directories that are no longer of |
| 4344 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong |
| 4345 | versions of source. You can correct the situation as follows: |
| 4346 | |
| 4347 | @enumerate |
| 4348 | @item |
| 4349 | Use @code{directory} with no argument to reset the source path to empty. |
| 4350 | |
| 4351 | @item |
| 4352 | Use @code{directory} with suitable arguments to reinstall the |
| 4353 | directories you want in the source path. You can add all the |
| 4354 | directories in one command. |
| 4355 | @end enumerate |
| 4356 | |
| 4357 | @node Machine Code |
| 4358 | @section Source and machine code |
| 4359 | |
| 4360 | You can use the command @code{info line} to map source lines to program |
| 4361 | addresses (and vice versa), and the command @code{disassemble} to display |
| 4362 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs |
| 4363 | mode, the @code{info line} command causes the arrow to point to the |
| 4364 | line specified. Also, @code{info line} prints addresses in symbolic form as |
| 4365 | well as hex. |
| 4366 | |
| 4367 | @table @code |
| 4368 | @kindex info line |
| 4369 | @item info line @var{linespec} |
| 4370 | Print the starting and ending addresses of the compiled code for |
| 4371 | source line @var{linespec}. You can specify source lines in any of |
| 4372 | the ways understood by the @code{list} command (@pxref{List, ,Printing |
| 4373 | source lines}). |
| 4374 | @end table |
| 4375 | |
| 4376 | For example, we can use @code{info line} to discover the location of |
| 4377 | the object code for the first line of function |
| 4378 | @code{m4_changequote}: |
| 4379 | |
| 4380 | @c FIXME: I think this example should also show the addresses in |
| 4381 | @c symbolic form, as they usually would be displayed. |
| 4382 | @smallexample |
| 4383 | (@value{GDBP}) info line m4_changequote |
| 4384 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. |
| 4385 | @end smallexample |
| 4386 | |
| 4387 | @noindent |
| 4388 | We can also inquire (using @code{*@var{addr}} as the form for |
| 4389 | @var{linespec}) what source line covers a particular address: |
| 4390 | @smallexample |
| 4391 | (@value{GDBP}) info line *0x63ff |
| 4392 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. |
| 4393 | @end smallexample |
| 4394 | |
| 4395 | @cindex @code{$_} and @code{info line} |
| 4396 | @kindex x@r{(examine), and} info line |
| 4397 | After @code{info line}, the default address for the @code{x} command |
| 4398 | is changed to the starting address of the line, so that @samp{x/i} is |
| 4399 | sufficient to begin examining the machine code (@pxref{Memory, |
| 4400 | ,Examining memory}). Also, this address is saved as the value of the |
| 4401 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience |
| 4402 | variables}). |
| 4403 | |
| 4404 | @table @code |
| 4405 | @kindex disassemble |
| 4406 | @cindex assembly instructions |
| 4407 | @cindex instructions, assembly |
| 4408 | @cindex machine instructions |
| 4409 | @cindex listing machine instructions |
| 4410 | @item disassemble |
| 4411 | This specialized command dumps a range of memory as machine |
| 4412 | instructions. The default memory range is the function surrounding the |
| 4413 | program counter of the selected frame. A single argument to this |
| 4414 | command is a program counter value; @value{GDBN} dumps the function |
| 4415 | surrounding this value. Two arguments specify a range of addresses |
| 4416 | (first inclusive, second exclusive) to dump. |
| 4417 | @end table |
| 4418 | |
| 4419 | The following example shows the disassembly of a range of addresses of |
| 4420 | HP PA-RISC 2.0 code: |
| 4421 | |
| 4422 | @smallexample |
| 4423 | (@value{GDBP}) disas 0x32c4 0x32e4 |
| 4424 | Dump of assembler code from 0x32c4 to 0x32e4: |
| 4425 | 0x32c4 <main+204>: addil 0,dp |
| 4426 | 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 |
| 4427 | 0x32cc <main+212>: ldil 0x3000,r31 |
| 4428 | 0x32d0 <main+216>: ble 0x3f8(sr4,r31) |
| 4429 | 0x32d4 <main+220>: ldo 0(r31),rp |
| 4430 | 0x32d8 <main+224>: addil -0x800,dp |
| 4431 | 0x32dc <main+228>: ldo 0x588(r1),r26 |
| 4432 | 0x32e0 <main+232>: ldil 0x3000,r31 |
| 4433 | End of assembler dump. |
| 4434 | @end smallexample |
| 4435 | |
| 4436 | Some architectures have more than one commonly-used set of instruction |
| 4437 | mnemonics or other syntax. |
| 4438 | |
| 4439 | @table @code |
| 4440 | @kindex set disassembly-flavor |
| 4441 | @cindex assembly instructions |
| 4442 | @cindex instructions, assembly |
| 4443 | @cindex machine instructions |
| 4444 | @cindex listing machine instructions |
| 4445 | @cindex Intel disassembly flavor |
| 4446 | @cindex AT&T disassembly flavor |
| 4447 | @item set disassembly-flavor @var{instruction-set} |
| 4448 | Select the instruction set to use when disassembling the |
| 4449 | program via the @code{disassemble} or @code{x/i} commands. |
| 4450 | |
| 4451 | Currently this command is only defined for the Intel x86 family. You |
| 4452 | can set @var{instruction-set} to either @code{intel} or @code{att}. |
| 4453 | The default is @code{att}, the AT&T flavor used by default by Unix |
| 4454 | assemblers for x86-based targets. |
| 4455 | @end table |
| 4456 | |
| 4457 | |
| 4458 | @node Data |
| 4459 | @chapter Examining Data |
| 4460 | |
| 4461 | @cindex printing data |
| 4462 | @cindex examining data |
| 4463 | @kindex print |
| 4464 | @kindex inspect |
| 4465 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not |
| 4466 | @c document because it is nonstandard... Under Epoch it displays in a |
| 4467 | @c different window or something like that. |
| 4468 | The usual way to examine data in your program is with the @code{print} |
| 4469 | command (abbreviated @code{p}), or its synonym @code{inspect}. It |
| 4470 | evaluates and prints the value of an expression of the language your |
| 4471 | program is written in (@pxref{Languages, ,Using @value{GDBN} with |
| 4472 | Different Languages}). |
| 4473 | |
| 4474 | @table @code |
| 4475 | @item print @var{expr} |
| 4476 | @itemx print /@var{f} @var{expr} |
| 4477 | @var{expr} is an expression (in the source language). By default the |
| 4478 | value of @var{expr} is printed in a format appropriate to its data type; |
| 4479 | you can choose a different format by specifying @samp{/@var{f}}, where |
| 4480 | @var{f} is a letter specifying the format; see @ref{Output Formats,,Output |
| 4481 | formats}. |
| 4482 | |
| 4483 | @item print |
| 4484 | @itemx print /@var{f} |
| 4485 | If you omit @var{expr}, @value{GDBN} displays the last value again (from the |
| 4486 | @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to |
| 4487 | conveniently inspect the same value in an alternative format. |
| 4488 | @end table |
| 4489 | |
| 4490 | A more low-level way of examining data is with the @code{x} command. |
| 4491 | It examines data in memory at a specified address and prints it in a |
| 4492 | specified format. @xref{Memory, ,Examining memory}. |
| 4493 | |
| 4494 | If you are interested in information about types, or about how the |
| 4495 | fields of a struct or a class are declared, use the @code{ptype @var{exp}} |
| 4496 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol |
| 4497 | Table}. |
| 4498 | |
| 4499 | @menu |
| 4500 | * Expressions:: Expressions |
| 4501 | * Variables:: Program variables |
| 4502 | * Arrays:: Artificial arrays |
| 4503 | * Output Formats:: Output formats |
| 4504 | * Memory:: Examining memory |
| 4505 | * Auto Display:: Automatic display |
| 4506 | * Print Settings:: Print settings |
| 4507 | * Value History:: Value history |
| 4508 | * Convenience Vars:: Convenience variables |
| 4509 | * Registers:: Registers |
| 4510 | * Floating Point Hardware:: Floating point hardware |
| 4511 | * Vector Unit:: Vector Unit |
| 4512 | * Memory Region Attributes:: Memory region attributes |
| 4513 | * Dump/Restore Files:: Copy between memory and a file |
| 4514 | * Character Sets:: Debugging programs that use a different |
| 4515 | character set than GDB does |
| 4516 | @end menu |
| 4517 | |
| 4518 | @node Expressions |
| 4519 | @section Expressions |
| 4520 | |
| 4521 | @cindex expressions |
| 4522 | @code{print} and many other @value{GDBN} commands accept an expression and |
| 4523 | compute its value. Any kind of constant, variable or operator defined |
| 4524 | by the programming language you are using is valid in an expression in |
| 4525 | @value{GDBN}. This includes conditional expressions, function calls, |
| 4526 | casts, and string constants. It also includes preprocessor macros, if |
| 4527 | you compiled your program to include this information; see |
| 4528 | @ref{Compilation}. |
| 4529 | |
| 4530 | @value{GDBN} supports array constants in expressions input by |
| 4531 | the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example, |
| 4532 | you can use the command @code{print @{1, 2, 3@}} to build up an array in |
| 4533 | memory that is @code{malloc}ed in the target program. |
| 4534 | |
| 4535 | Because C is so widespread, most of the expressions shown in examples in |
| 4536 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different |
| 4537 | Languages}, for information on how to use expressions in other |
| 4538 | languages. |
| 4539 | |
| 4540 | In this section, we discuss operators that you can use in @value{GDBN} |
| 4541 | expressions regardless of your programming language. |
| 4542 | |
| 4543 | Casts are supported in all languages, not just in C, because it is so |
| 4544 | useful to cast a number into a pointer in order to examine a structure |
| 4545 | at that address in memory. |
| 4546 | @c FIXME: casts supported---Mod2 true? |
| 4547 | |
| 4548 | @value{GDBN} supports these operators, in addition to those common |
| 4549 | to programming languages: |
| 4550 | |
| 4551 | @table @code |
| 4552 | @item @@ |
| 4553 | @samp{@@} is a binary operator for treating parts of memory as arrays. |
| 4554 | @xref{Arrays, ,Artificial arrays}, for more information. |
| 4555 | |
| 4556 | @item :: |
| 4557 | @samp{::} allows you to specify a variable in terms of the file or |
| 4558 | function where it is defined. @xref{Variables, ,Program variables}. |
| 4559 | |
| 4560 | @cindex @{@var{type}@} |
| 4561 | @cindex type casting memory |
| 4562 | @cindex memory, viewing as typed object |
| 4563 | @cindex casts, to view memory |
| 4564 | @item @{@var{type}@} @var{addr} |
| 4565 | Refers to an object of type @var{type} stored at address @var{addr} in |
| 4566 | memory. @var{addr} may be any expression whose value is an integer or |
| 4567 | pointer (but parentheses are required around binary operators, just as in |
| 4568 | a cast). This construct is allowed regardless of what kind of data is |
| 4569 | normally supposed to reside at @var{addr}. |
| 4570 | @end table |
| 4571 | |
| 4572 | @node Variables |
| 4573 | @section Program variables |
| 4574 | |
| 4575 | The most common kind of expression to use is the name of a variable |
| 4576 | in your program. |
| 4577 | |
| 4578 | Variables in expressions are understood in the selected stack frame |
| 4579 | (@pxref{Selection, ,Selecting a frame}); they must be either: |
| 4580 | |
| 4581 | @itemize @bullet |
| 4582 | @item |
| 4583 | global (or file-static) |
| 4584 | @end itemize |
| 4585 | |
| 4586 | @noindent or |
| 4587 | |
| 4588 | @itemize @bullet |
| 4589 | @item |
| 4590 | visible according to the scope rules of the |
| 4591 | programming language from the point of execution in that frame |
| 4592 | @end itemize |
| 4593 | |
| 4594 | @noindent This means that in the function |
| 4595 | |
| 4596 | @smallexample |
| 4597 | foo (a) |
| 4598 | int a; |
| 4599 | @{ |
| 4600 | bar (a); |
| 4601 | @{ |
| 4602 | int b = test (); |
| 4603 | bar (b); |
| 4604 | @} |
| 4605 | @} |
| 4606 | @end smallexample |
| 4607 | |
| 4608 | @noindent |
| 4609 | you can examine and use the variable @code{a} whenever your program is |
| 4610 | executing within the function @code{foo}, but you can only use or |
| 4611 | examine the variable @code{b} while your program is executing inside |
| 4612 | the block where @code{b} is declared. |
| 4613 | |
| 4614 | @cindex variable name conflict |
| 4615 | There is an exception: you can refer to a variable or function whose |
| 4616 | scope is a single source file even if the current execution point is not |
| 4617 | in this file. But it is possible to have more than one such variable or |
| 4618 | function with the same name (in different source files). If that |
| 4619 | happens, referring to that name has unpredictable effects. If you wish, |
| 4620 | you can specify a static variable in a particular function or file, |
| 4621 | using the colon-colon notation: |
| 4622 | |
| 4623 | @cindex colon-colon, context for variables/functions |
| 4624 | @iftex |
| 4625 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? |
| 4626 | @cindex @code{::}, context for variables/functions |
| 4627 | @end iftex |
| 4628 | @smallexample |
| 4629 | @var{file}::@var{variable} |
| 4630 | @var{function}::@var{variable} |
| 4631 | @end smallexample |
| 4632 | |
| 4633 | @noindent |
| 4634 | Here @var{file} or @var{function} is the name of the context for the |
| 4635 | static @var{variable}. In the case of file names, you can use quotes to |
| 4636 | make sure @value{GDBN} parses the file name as a single word---for example, |
| 4637 | to print a global value of @code{x} defined in @file{f2.c}: |
| 4638 | |
| 4639 | @smallexample |
| 4640 | (@value{GDBP}) p 'f2.c'::x |
| 4641 | @end smallexample |
| 4642 | |
| 4643 | @cindex C@t{++} scope resolution |
| 4644 | This use of @samp{::} is very rarely in conflict with the very similar |
| 4645 | use of the same notation in C@t{++}. @value{GDBN} also supports use of the C@t{++} |
| 4646 | scope resolution operator in @value{GDBN} expressions. |
| 4647 | @c FIXME: Um, so what happens in one of those rare cases where it's in |
| 4648 | @c conflict?? --mew |
| 4649 | |
| 4650 | @cindex wrong values |
| 4651 | @cindex variable values, wrong |
| 4652 | @quotation |
| 4653 | @emph{Warning:} Occasionally, a local variable may appear to have the |
| 4654 | wrong value at certain points in a function---just after entry to a new |
| 4655 | scope, and just before exit. |
| 4656 | @end quotation |
| 4657 | You may see this problem when you are stepping by machine instructions. |
| 4658 | This is because, on most machines, it takes more than one instruction to |
| 4659 | set up a stack frame (including local variable definitions); if you are |
| 4660 | stepping by machine instructions, variables may appear to have the wrong |
| 4661 | values until the stack frame is completely built. On exit, it usually |
| 4662 | also takes more than one machine instruction to destroy a stack frame; |
| 4663 | after you begin stepping through that group of instructions, local |
| 4664 | variable definitions may be gone. |
| 4665 | |
| 4666 | This may also happen when the compiler does significant optimizations. |
| 4667 | To be sure of always seeing accurate values, turn off all optimization |
| 4668 | when compiling. |
| 4669 | |
| 4670 | @cindex ``No symbol "foo" in current context'' |
| 4671 | Another possible effect of compiler optimizations is to optimize |
| 4672 | unused variables out of existence, or assign variables to registers (as |
| 4673 | opposed to memory addresses). Depending on the support for such cases |
| 4674 | offered by the debug info format used by the compiler, @value{GDBN} |
| 4675 | might not be able to display values for such local variables. If that |
| 4676 | happens, @value{GDBN} will print a message like this: |
| 4677 | |
| 4678 | @smallexample |
| 4679 | No symbol "foo" in current context. |
| 4680 | @end smallexample |
| 4681 | |
| 4682 | To solve such problems, either recompile without optimizations, or use a |
| 4683 | different debug info format, if the compiler supports several such |
| 4684 | formats. For example, @value{NGCC}, the @sc{gnu} C/C@t{++} compiler usually |
| 4685 | supports the @samp{-gstabs} option. @samp{-gstabs} produces debug info |
| 4686 | in a format that is superior to formats such as COFF. You may be able |
| 4687 | to use DWARF2 (@samp{-gdwarf-2}), which is also an effective form for |
| 4688 | debug info. See @ref{Debugging Options,,Options for Debugging Your |
| 4689 | Program or @sc{gnu} CC, gcc.info, Using @sc{gnu} CC}, for more |
| 4690 | information. |
| 4691 | |
| 4692 | |
| 4693 | @node Arrays |
| 4694 | @section Artificial arrays |
| 4695 | |
| 4696 | @cindex artificial array |
| 4697 | @kindex @@@r{, referencing memory as an array} |
| 4698 | It is often useful to print out several successive objects of the |
| 4699 | same type in memory; a section of an array, or an array of |
| 4700 | dynamically determined size for which only a pointer exists in the |
| 4701 | program. |
| 4702 | |
| 4703 | You can do this by referring to a contiguous span of memory as an |
| 4704 | @dfn{artificial array}, using the binary operator @samp{@@}. The left |
| 4705 | operand of @samp{@@} should be the first element of the desired array |
| 4706 | and be an individual object. The right operand should be the desired length |
| 4707 | of the array. The result is an array value whose elements are all of |
| 4708 | the type of the left argument. The first element is actually the left |
| 4709 | argument; the second element comes from bytes of memory immediately |
| 4710 | following those that hold the first element, and so on. Here is an |
| 4711 | example. If a program says |
| 4712 | |
| 4713 | @smallexample |
| 4714 | int *array = (int *) malloc (len * sizeof (int)); |
| 4715 | @end smallexample |
| 4716 | |
| 4717 | @noindent |
| 4718 | you can print the contents of @code{array} with |
| 4719 | |
| 4720 | @smallexample |
| 4721 | p *array@@len |
| 4722 | @end smallexample |
| 4723 | |
| 4724 | The left operand of @samp{@@} must reside in memory. Array values made |
| 4725 | with @samp{@@} in this way behave just like other arrays in terms of |
| 4726 | subscripting, and are coerced to pointers when used in expressions. |
| 4727 | Artificial arrays most often appear in expressions via the value history |
| 4728 | (@pxref{Value History, ,Value history}), after printing one out. |
| 4729 | |
| 4730 | Another way to create an artificial array is to use a cast. |
| 4731 | This re-interprets a value as if it were an array. |
| 4732 | The value need not be in memory: |
| 4733 | @smallexample |
| 4734 | (@value{GDBP}) p/x (short[2])0x12345678 |
| 4735 | $1 = @{0x1234, 0x5678@} |
| 4736 | @end smallexample |
| 4737 | |
| 4738 | As a convenience, if you leave the array length out (as in |
| 4739 | @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill |
| 4740 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: |
| 4741 | @smallexample |
| 4742 | (@value{GDBP}) p/x (short[])0x12345678 |
| 4743 | $2 = @{0x1234, 0x5678@} |
| 4744 | @end smallexample |
| 4745 | |
| 4746 | Sometimes the artificial array mechanism is not quite enough; in |
| 4747 | moderately complex data structures, the elements of interest may not |
| 4748 | actually be adjacent---for example, if you are interested in the values |
| 4749 | of pointers in an array. One useful work-around in this situation is |
| 4750 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience |
| 4751 | variables}) as a counter in an expression that prints the first |
| 4752 | interesting value, and then repeat that expression via @key{RET}. For |
| 4753 | instance, suppose you have an array @code{dtab} of pointers to |
| 4754 | structures, and you are interested in the values of a field @code{fv} |
| 4755 | in each structure. Here is an example of what you might type: |
| 4756 | |
| 4757 | @smallexample |
| 4758 | set $i = 0 |
| 4759 | p dtab[$i++]->fv |
| 4760 | @key{RET} |
| 4761 | @key{RET} |
| 4762 | @dots{} |
| 4763 | @end smallexample |
| 4764 | |
| 4765 | @node Output Formats |
| 4766 | @section Output formats |
| 4767 | |
| 4768 | @cindex formatted output |
| 4769 | @cindex output formats |
| 4770 | By default, @value{GDBN} prints a value according to its data type. Sometimes |
| 4771 | this is not what you want. For example, you might want to print a number |
| 4772 | in hex, or a pointer in decimal. Or you might want to view data in memory |
| 4773 | at a certain address as a character string or as an instruction. To do |
| 4774 | these things, specify an @dfn{output format} when you print a value. |
| 4775 | |
| 4776 | The simplest use of output formats is to say how to print a value |
| 4777 | already computed. This is done by starting the arguments of the |
| 4778 | @code{print} command with a slash and a format letter. The format |
| 4779 | letters supported are: |
| 4780 | |
| 4781 | @table @code |
| 4782 | @item x |
| 4783 | Regard the bits of the value as an integer, and print the integer in |
| 4784 | hexadecimal. |
| 4785 | |
| 4786 | @item d |
| 4787 | Print as integer in signed decimal. |
| 4788 | |
| 4789 | @item u |
| 4790 | Print as integer in unsigned decimal. |
| 4791 | |
| 4792 | @item o |
| 4793 | Print as integer in octal. |
| 4794 | |
| 4795 | @item t |
| 4796 | Print as integer in binary. The letter @samp{t} stands for ``two''. |
| 4797 | @footnote{@samp{b} cannot be used because these format letters are also |
| 4798 | used with the @code{x} command, where @samp{b} stands for ``byte''; |
| 4799 | see @ref{Memory,,Examining memory}.} |
| 4800 | |
| 4801 | @item a |
| 4802 | @cindex unknown address, locating |
| 4803 | @cindex locate address |
| 4804 | Print as an address, both absolute in hexadecimal and as an offset from |
| 4805 | the nearest preceding symbol. You can use this format used to discover |
| 4806 | where (in what function) an unknown address is located: |
| 4807 | |
| 4808 | @smallexample |
| 4809 | (@value{GDBP}) p/a 0x54320 |
| 4810 | $3 = 0x54320 <_initialize_vx+396> |
| 4811 | @end smallexample |
| 4812 | |
| 4813 | @noindent |
| 4814 | The command @code{info symbol 0x54320} yields similar results. |
| 4815 | @xref{Symbols, info symbol}. |
| 4816 | |
| 4817 | @item c |
| 4818 | Regard as an integer and print it as a character constant. |
| 4819 | |
| 4820 | @item f |
| 4821 | Regard the bits of the value as a floating point number and print |
| 4822 | using typical floating point syntax. |
| 4823 | @end table |
| 4824 | |
| 4825 | For example, to print the program counter in hex (@pxref{Registers}), type |
| 4826 | |
| 4827 | @smallexample |
| 4828 | p/x $pc |
| 4829 | @end smallexample |
| 4830 | |
| 4831 | @noindent |
| 4832 | Note that no space is required before the slash; this is because command |
| 4833 | names in @value{GDBN} cannot contain a slash. |
| 4834 | |
| 4835 | To reprint the last value in the value history with a different format, |
| 4836 | you can use the @code{print} command with just a format and no |
| 4837 | expression. For example, @samp{p/x} reprints the last value in hex. |
| 4838 | |
| 4839 | @node Memory |
| 4840 | @section Examining memory |
| 4841 | |
| 4842 | You can use the command @code{x} (for ``examine'') to examine memory in |
| 4843 | any of several formats, independently of your program's data types. |
| 4844 | |
| 4845 | @cindex examining memory |
| 4846 | @table @code |
| 4847 | @kindex x @r{(examine memory)} |
| 4848 | @item x/@var{nfu} @var{addr} |
| 4849 | @itemx x @var{addr} |
| 4850 | @itemx x |
| 4851 | Use the @code{x} command to examine memory. |
| 4852 | @end table |
| 4853 | |
| 4854 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how |
| 4855 | much memory to display and how to format it; @var{addr} is an |
| 4856 | expression giving the address where you want to start displaying memory. |
| 4857 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. |
| 4858 | Several commands set convenient defaults for @var{addr}. |
| 4859 | |
| 4860 | @table @r |
| 4861 | @item @var{n}, the repeat count |
| 4862 | The repeat count is a decimal integer; the default is 1. It specifies |
| 4863 | how much memory (counting by units @var{u}) to display. |
| 4864 | @c This really is **decimal**; unaffected by 'set radix' as of GDB |
| 4865 | @c 4.1.2. |
| 4866 | |
| 4867 | @item @var{f}, the display format |
| 4868 | The display format is one of the formats used by @code{print}, |
| 4869 | @samp{s} (null-terminated string), or @samp{i} (machine instruction). |
| 4870 | The default is @samp{x} (hexadecimal) initially. |
| 4871 | The default changes each time you use either @code{x} or @code{print}. |
| 4872 | |
| 4873 | @item @var{u}, the unit size |
| 4874 | The unit size is any of |
| 4875 | |
| 4876 | @table @code |
| 4877 | @item b |
| 4878 | Bytes. |
| 4879 | @item h |
| 4880 | Halfwords (two bytes). |
| 4881 | @item w |
| 4882 | Words (four bytes). This is the initial default. |
| 4883 | @item g |
| 4884 | Giant words (eight bytes). |
| 4885 | @end table |
| 4886 | |
| 4887 | Each time you specify a unit size with @code{x}, that size becomes the |
| 4888 | default unit the next time you use @code{x}. (For the @samp{s} and |
| 4889 | @samp{i} formats, the unit size is ignored and is normally not written.) |
| 4890 | |
| 4891 | @item @var{addr}, starting display address |
| 4892 | @var{addr} is the address where you want @value{GDBN} to begin displaying |
| 4893 | memory. The expression need not have a pointer value (though it may); |
| 4894 | it is always interpreted as an integer address of a byte of memory. |
| 4895 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for |
| 4896 | @var{addr} is usually just after the last address examined---but several |
| 4897 | other commands also set the default address: @code{info breakpoints} (to |
| 4898 | the address of the last breakpoint listed), @code{info line} (to the |
| 4899 | starting address of a line), and @code{print} (if you use it to display |
| 4900 | a value from memory). |
| 4901 | @end table |
| 4902 | |
| 4903 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords |
| 4904 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), |
| 4905 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four |
| 4906 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; |
| 4907 | @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). |
| 4908 | |
| 4909 | Since the letters indicating unit sizes are all distinct from the |
| 4910 | letters specifying output formats, you do not have to remember whether |
| 4911 | unit size or format comes first; either order works. The output |
| 4912 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. |
| 4913 | (However, the count @var{n} must come first; @samp{wx4} does not work.) |
| 4914 | |
| 4915 | Even though the unit size @var{u} is ignored for the formats @samp{s} |
| 4916 | and @samp{i}, you might still want to use a count @var{n}; for example, |
| 4917 | @samp{3i} specifies that you want to see three machine instructions, |
| 4918 | including any operands. The command @code{disassemble} gives an |
| 4919 | alternative way of inspecting machine instructions; see @ref{Machine |
| 4920 | Code,,Source and machine code}. |
| 4921 | |
| 4922 | All the defaults for the arguments to @code{x} are designed to make it |
| 4923 | easy to continue scanning memory with minimal specifications each time |
| 4924 | you use @code{x}. For example, after you have inspected three machine |
| 4925 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven |
| 4926 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, |
| 4927 | the repeat count @var{n} is used again; the other arguments default as |
| 4928 | for successive uses of @code{x}. |
| 4929 | |
| 4930 | @cindex @code{$_}, @code{$__}, and value history |
| 4931 | The addresses and contents printed by the @code{x} command are not saved |
| 4932 | in the value history because there is often too much of them and they |
| 4933 | would get in the way. Instead, @value{GDBN} makes these values available for |
| 4934 | subsequent use in expressions as values of the convenience variables |
| 4935 | @code{$_} and @code{$__}. After an @code{x} command, the last address |
| 4936 | examined is available for use in expressions in the convenience variable |
| 4937 | @code{$_}. The contents of that address, as examined, are available in |
| 4938 | the convenience variable @code{$__}. |
| 4939 | |
| 4940 | If the @code{x} command has a repeat count, the address and contents saved |
| 4941 | are from the last memory unit printed; this is not the same as the last |
| 4942 | address printed if several units were printed on the last line of output. |
| 4943 | |
| 4944 | @node Auto Display |
| 4945 | @section Automatic display |
| 4946 | @cindex automatic display |
| 4947 | @cindex display of expressions |
| 4948 | |
| 4949 | If you find that you want to print the value of an expression frequently |
| 4950 | (to see how it changes), you might want to add it to the @dfn{automatic |
| 4951 | display list} so that @value{GDBN} prints its value each time your program stops. |
| 4952 | Each expression added to the list is given a number to identify it; |
| 4953 | to remove an expression from the list, you specify that number. |
| 4954 | The automatic display looks like this: |
| 4955 | |
| 4956 | @smallexample |
| 4957 | 2: foo = 38 |
| 4958 | 3: bar[5] = (struct hack *) 0x3804 |
| 4959 | @end smallexample |
| 4960 | |
| 4961 | @noindent |
| 4962 | This display shows item numbers, expressions and their current values. As with |
| 4963 | displays you request manually using @code{x} or @code{print}, you can |
| 4964 | specify the output format you prefer; in fact, @code{display} decides |
| 4965 | whether to use @code{print} or @code{x} depending on how elaborate your |
| 4966 | format specification is---it uses @code{x} if you specify a unit size, |
| 4967 | or one of the two formats (@samp{i} and @samp{s}) that are only |
| 4968 | supported by @code{x}; otherwise it uses @code{print}. |
| 4969 | |
| 4970 | @table @code |
| 4971 | @kindex display |
| 4972 | @item display @var{expr} |
| 4973 | Add the expression @var{expr} to the list of expressions to display |
| 4974 | each time your program stops. @xref{Expressions, ,Expressions}. |
| 4975 | |
| 4976 | @code{display} does not repeat if you press @key{RET} again after using it. |
| 4977 | |
| 4978 | @item display/@var{fmt} @var{expr} |
| 4979 | For @var{fmt} specifying only a display format and not a size or |
| 4980 | count, add the expression @var{expr} to the auto-display list but |
| 4981 | arrange to display it each time in the specified format @var{fmt}. |
| 4982 | @xref{Output Formats,,Output formats}. |
| 4983 | |
| 4984 | @item display/@var{fmt} @var{addr} |
| 4985 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a |
| 4986 | number of units, add the expression @var{addr} as a memory address to |
| 4987 | be examined each time your program stops. Examining means in effect |
| 4988 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. |
| 4989 | @end table |
| 4990 | |
| 4991 | For example, @samp{display/i $pc} can be helpful, to see the machine |
| 4992 | instruction about to be executed each time execution stops (@samp{$pc} |
| 4993 | is a common name for the program counter; @pxref{Registers, ,Registers}). |
| 4994 | |
| 4995 | @table @code |
| 4996 | @kindex delete display |
| 4997 | @kindex undisplay |
| 4998 | @item undisplay @var{dnums}@dots{} |
| 4999 | @itemx delete display @var{dnums}@dots{} |
| 5000 | Remove item numbers @var{dnums} from the list of expressions to display. |
| 5001 | |
| 5002 | @code{undisplay} does not repeat if you press @key{RET} after using it. |
| 5003 | (Otherwise you would just get the error @samp{No display number @dots{}}.) |
| 5004 | |
| 5005 | @kindex disable display |
| 5006 | @item disable display @var{dnums}@dots{} |
| 5007 | Disable the display of item numbers @var{dnums}. A disabled display |
| 5008 | item is not printed automatically, but is not forgotten. It may be |
| 5009 | enabled again later. |
| 5010 | |
| 5011 | @kindex enable display |
| 5012 | @item enable display @var{dnums}@dots{} |
| 5013 | Enable display of item numbers @var{dnums}. It becomes effective once |
| 5014 | again in auto display of its expression, until you specify otherwise. |
| 5015 | |
| 5016 | @item display |
| 5017 | Display the current values of the expressions on the list, just as is |
| 5018 | done when your program stops. |
| 5019 | |
| 5020 | @kindex info display |
| 5021 | @item info display |
| 5022 | Print the list of expressions previously set up to display |
| 5023 | automatically, each one with its item number, but without showing the |
| 5024 | values. This includes disabled expressions, which are marked as such. |
| 5025 | It also includes expressions which would not be displayed right now |
| 5026 | because they refer to automatic variables not currently available. |
| 5027 | @end table |
| 5028 | |
| 5029 | If a display expression refers to local variables, then it does not make |
| 5030 | sense outside the lexical context for which it was set up. Such an |
| 5031 | expression is disabled when execution enters a context where one of its |
| 5032 | variables is not defined. For example, if you give the command |
| 5033 | @code{display last_char} while inside a function with an argument |
| 5034 | @code{last_char}, @value{GDBN} displays this argument while your program |
| 5035 | continues to stop inside that function. When it stops elsewhere---where |
| 5036 | there is no variable @code{last_char}---the display is disabled |
| 5037 | automatically. The next time your program stops where @code{last_char} |
| 5038 | is meaningful, you can enable the display expression once again. |
| 5039 | |
| 5040 | @node Print Settings |
| 5041 | @section Print settings |
| 5042 | |
| 5043 | @cindex format options |
| 5044 | @cindex print settings |
| 5045 | @value{GDBN} provides the following ways to control how arrays, structures, |
| 5046 | and symbols are printed. |
| 5047 | |
| 5048 | @noindent |
| 5049 | These settings are useful for debugging programs in any language: |
| 5050 | |
| 5051 | @table @code |
| 5052 | @kindex set print address |
| 5053 | @item set print address |
| 5054 | @itemx set print address on |
| 5055 | @value{GDBN} prints memory addresses showing the location of stack |
| 5056 | traces, structure values, pointer values, breakpoints, and so forth, |
| 5057 | even when it also displays the contents of those addresses. The default |
| 5058 | is @code{on}. For example, this is what a stack frame display looks like with |
| 5059 | @code{set print address on}: |
| 5060 | |
| 5061 | @smallexample |
| 5062 | @group |
| 5063 | (@value{GDBP}) f |
| 5064 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") |
| 5065 | at input.c:530 |
| 5066 | 530 if (lquote != def_lquote) |
| 5067 | @end group |
| 5068 | @end smallexample |
| 5069 | |
| 5070 | @item set print address off |
| 5071 | Do not print addresses when displaying their contents. For example, |
| 5072 | this is the same stack frame displayed with @code{set print address off}: |
| 5073 | |
| 5074 | @smallexample |
| 5075 | @group |
| 5076 | (@value{GDBP}) set print addr off |
| 5077 | (@value{GDBP}) f |
| 5078 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 |
| 5079 | 530 if (lquote != def_lquote) |
| 5080 | @end group |
| 5081 | @end smallexample |
| 5082 | |
| 5083 | You can use @samp{set print address off} to eliminate all machine |
| 5084 | dependent displays from the @value{GDBN} interface. For example, with |
| 5085 | @code{print address off}, you should get the same text for backtraces on |
| 5086 | all machines---whether or not they involve pointer arguments. |
| 5087 | |
| 5088 | @kindex show print address |
| 5089 | @item show print address |
| 5090 | Show whether or not addresses are to be printed. |
| 5091 | @end table |
| 5092 | |
| 5093 | When @value{GDBN} prints a symbolic address, it normally prints the |
| 5094 | closest earlier symbol plus an offset. If that symbol does not uniquely |
| 5095 | identify the address (for example, it is a name whose scope is a single |
| 5096 | source file), you may need to clarify. One way to do this is with |
| 5097 | @code{info line}, for example @samp{info line *0x4537}. Alternately, |
| 5098 | you can set @value{GDBN} to print the source file and line number when |
| 5099 | it prints a symbolic address: |
| 5100 | |
| 5101 | @table @code |
| 5102 | @kindex set print symbol-filename |
| 5103 | @item set print symbol-filename on |
| 5104 | Tell @value{GDBN} to print the source file name and line number of a |
| 5105 | symbol in the symbolic form of an address. |
| 5106 | |
| 5107 | @item set print symbol-filename off |
| 5108 | Do not print source file name and line number of a symbol. This is the |
| 5109 | default. |
| 5110 | |
| 5111 | @kindex show print symbol-filename |
| 5112 | @item show print symbol-filename |
| 5113 | Show whether or not @value{GDBN} will print the source file name and |
| 5114 | line number of a symbol in the symbolic form of an address. |
| 5115 | @end table |
| 5116 | |
| 5117 | Another situation where it is helpful to show symbol filenames and line |
| 5118 | numbers is when disassembling code; @value{GDBN} shows you the line |
| 5119 | number and source file that corresponds to each instruction. |
| 5120 | |
| 5121 | Also, you may wish to see the symbolic form only if the address being |
| 5122 | printed is reasonably close to the closest earlier symbol: |
| 5123 | |
| 5124 | @table @code |
| 5125 | @kindex set print max-symbolic-offset |
| 5126 | @item set print max-symbolic-offset @var{max-offset} |
| 5127 | Tell @value{GDBN} to only display the symbolic form of an address if the |
| 5128 | offset between the closest earlier symbol and the address is less than |
| 5129 | @var{max-offset}. The default is 0, which tells @value{GDBN} |
| 5130 | to always print the symbolic form of an address if any symbol precedes it. |
| 5131 | |
| 5132 | @kindex show print max-symbolic-offset |
| 5133 | @item show print max-symbolic-offset |
| 5134 | Ask how large the maximum offset is that @value{GDBN} prints in a |
| 5135 | symbolic address. |
| 5136 | @end table |
| 5137 | |
| 5138 | @cindex wild pointer, interpreting |
| 5139 | @cindex pointer, finding referent |
| 5140 | If you have a pointer and you are not sure where it points, try |
| 5141 | @samp{set print symbol-filename on}. Then you can determine the name |
| 5142 | and source file location of the variable where it points, using |
| 5143 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. |
| 5144 | For example, here @value{GDBN} shows that a variable @code{ptt} points |
| 5145 | at another variable @code{t}, defined in @file{hi2.c}: |
| 5146 | |
| 5147 | @smallexample |
| 5148 | (@value{GDBP}) set print symbol-filename on |
| 5149 | (@value{GDBP}) p/a ptt |
| 5150 | $4 = 0xe008 <t in hi2.c> |
| 5151 | @end smallexample |
| 5152 | |
| 5153 | @quotation |
| 5154 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} |
| 5155 | does not show the symbol name and filename of the referent, even with |
| 5156 | the appropriate @code{set print} options turned on. |
| 5157 | @end quotation |
| 5158 | |
| 5159 | Other settings control how different kinds of objects are printed: |
| 5160 | |
| 5161 | @table @code |
| 5162 | @kindex set print array |
| 5163 | @item set print array |
| 5164 | @itemx set print array on |
| 5165 | Pretty print arrays. This format is more convenient to read, |
| 5166 | but uses more space. The default is off. |
| 5167 | |
| 5168 | @item set print array off |
| 5169 | Return to compressed format for arrays. |
| 5170 | |
| 5171 | @kindex show print array |
| 5172 | @item show print array |
| 5173 | Show whether compressed or pretty format is selected for displaying |
| 5174 | arrays. |
| 5175 | |
| 5176 | @kindex set print elements |
| 5177 | @item set print elements @var{number-of-elements} |
| 5178 | Set a limit on how many elements of an array @value{GDBN} will print. |
| 5179 | If @value{GDBN} is printing a large array, it stops printing after it has |
| 5180 | printed the number of elements set by the @code{set print elements} command. |
| 5181 | This limit also applies to the display of strings. |
| 5182 | When @value{GDBN} starts, this limit is set to 200. |
| 5183 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
| 5184 | |
| 5185 | @kindex show print elements |
| 5186 | @item show print elements |
| 5187 | Display the number of elements of a large array that @value{GDBN} will print. |
| 5188 | If the number is 0, then the printing is unlimited. |
| 5189 | |
| 5190 | @kindex set print null-stop |
| 5191 | @item set print null-stop |
| 5192 | Cause @value{GDBN} to stop printing the characters of an array when the first |
| 5193 | @sc{null} is encountered. This is useful when large arrays actually |
| 5194 | contain only short strings. |
| 5195 | The default is off. |
| 5196 | |
| 5197 | @kindex set print pretty |
| 5198 | @item set print pretty on |
| 5199 | Cause @value{GDBN} to print structures in an indented format with one member |
| 5200 | per line, like this: |
| 5201 | |
| 5202 | @smallexample |
| 5203 | @group |
| 5204 | $1 = @{ |
| 5205 | next = 0x0, |
| 5206 | flags = @{ |
| 5207 | sweet = 1, |
| 5208 | sour = 1 |
| 5209 | @}, |
| 5210 | meat = 0x54 "Pork" |
| 5211 | @} |
| 5212 | @end group |
| 5213 | @end smallexample |
| 5214 | |
| 5215 | @item set print pretty off |
| 5216 | Cause @value{GDBN} to print structures in a compact format, like this: |
| 5217 | |
| 5218 | @smallexample |
| 5219 | @group |
| 5220 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ |
| 5221 | meat = 0x54 "Pork"@} |
| 5222 | @end group |
| 5223 | @end smallexample |
| 5224 | |
| 5225 | @noindent |
| 5226 | This is the default format. |
| 5227 | |
| 5228 | @kindex show print pretty |
| 5229 | @item show print pretty |
| 5230 | Show which format @value{GDBN} is using to print structures. |
| 5231 | |
| 5232 | @kindex set print sevenbit-strings |
| 5233 | @item set print sevenbit-strings on |
| 5234 | Print using only seven-bit characters; if this option is set, |
| 5235 | @value{GDBN} displays any eight-bit characters (in strings or |
| 5236 | character values) using the notation @code{\}@var{nnn}. This setting is |
| 5237 | best if you are working in English (@sc{ascii}) and you use the |
| 5238 | high-order bit of characters as a marker or ``meta'' bit. |
| 5239 | |
| 5240 | @item set print sevenbit-strings off |
| 5241 | Print full eight-bit characters. This allows the use of more |
| 5242 | international character sets, and is the default. |
| 5243 | |
| 5244 | @kindex show print sevenbit-strings |
| 5245 | @item show print sevenbit-strings |
| 5246 | Show whether or not @value{GDBN} is printing only seven-bit characters. |
| 5247 | |
| 5248 | @kindex set print union |
| 5249 | @item set print union on |
| 5250 | Tell @value{GDBN} to print unions which are contained in structures. This |
| 5251 | is the default setting. |
| 5252 | |
| 5253 | @item set print union off |
| 5254 | Tell @value{GDBN} not to print unions which are contained in structures. |
| 5255 | |
| 5256 | @kindex show print union |
| 5257 | @item show print union |
| 5258 | Ask @value{GDBN} whether or not it will print unions which are contained in |
| 5259 | structures. |
| 5260 | |
| 5261 | For example, given the declarations |
| 5262 | |
| 5263 | @smallexample |
| 5264 | typedef enum @{Tree, Bug@} Species; |
| 5265 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; |
| 5266 | typedef enum @{Caterpillar, Cocoon, Butterfly@} |
| 5267 | Bug_forms; |
| 5268 | |
| 5269 | struct thing @{ |
| 5270 | Species it; |
| 5271 | union @{ |
| 5272 | Tree_forms tree; |
| 5273 | Bug_forms bug; |
| 5274 | @} form; |
| 5275 | @}; |
| 5276 | |
| 5277 | struct thing foo = @{Tree, @{Acorn@}@}; |
| 5278 | @end smallexample |
| 5279 | |
| 5280 | @noindent |
| 5281 | with @code{set print union on} in effect @samp{p foo} would print |
| 5282 | |
| 5283 | @smallexample |
| 5284 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} |
| 5285 | @end smallexample |
| 5286 | |
| 5287 | @noindent |
| 5288 | and with @code{set print union off} in effect it would print |
| 5289 | |
| 5290 | @smallexample |
| 5291 | $1 = @{it = Tree, form = @{...@}@} |
| 5292 | @end smallexample |
| 5293 | @end table |
| 5294 | |
| 5295 | @need 1000 |
| 5296 | @noindent |
| 5297 | These settings are of interest when debugging C@t{++} programs: |
| 5298 | |
| 5299 | @table @code |
| 5300 | @cindex demangling |
| 5301 | @kindex set print demangle |
| 5302 | @item set print demangle |
| 5303 | @itemx set print demangle on |
| 5304 | Print C@t{++} names in their source form rather than in the encoded |
| 5305 | (``mangled'') form passed to the assembler and linker for type-safe |
| 5306 | linkage. The default is on. |
| 5307 | |
| 5308 | @kindex show print demangle |
| 5309 | @item show print demangle |
| 5310 | Show whether C@t{++} names are printed in mangled or demangled form. |
| 5311 | |
| 5312 | @kindex set print asm-demangle |
| 5313 | @item set print asm-demangle |
| 5314 | @itemx set print asm-demangle on |
| 5315 | Print C@t{++} names in their source form rather than their mangled form, even |
| 5316 | in assembler code printouts such as instruction disassemblies. |
| 5317 | The default is off. |
| 5318 | |
| 5319 | @kindex show print asm-demangle |
| 5320 | @item show print asm-demangle |
| 5321 | Show whether C@t{++} names in assembly listings are printed in mangled |
| 5322 | or demangled form. |
| 5323 | |
| 5324 | @kindex set demangle-style |
| 5325 | @cindex C@t{++} symbol decoding style |
| 5326 | @cindex symbol decoding style, C@t{++} |
| 5327 | @item set demangle-style @var{style} |
| 5328 | Choose among several encoding schemes used by different compilers to |
| 5329 | represent C@t{++} names. The choices for @var{style} are currently: |
| 5330 | |
| 5331 | @table @code |
| 5332 | @item auto |
| 5333 | Allow @value{GDBN} to choose a decoding style by inspecting your program. |
| 5334 | |
| 5335 | @item gnu |
| 5336 | Decode based on the @sc{gnu} C@t{++} compiler (@code{g++}) encoding algorithm. |
| 5337 | This is the default. |
| 5338 | |
| 5339 | @item hp |
| 5340 | Decode based on the HP ANSI C@t{++} (@code{aCC}) encoding algorithm. |
| 5341 | |
| 5342 | @item lucid |
| 5343 | Decode based on the Lucid C@t{++} compiler (@code{lcc}) encoding algorithm. |
| 5344 | |
| 5345 | @item arm |
| 5346 | Decode using the algorithm in the @cite{C@t{++} Annotated Reference Manual}. |
| 5347 | @strong{Warning:} this setting alone is not sufficient to allow |
| 5348 | debugging @code{cfront}-generated executables. @value{GDBN} would |
| 5349 | require further enhancement to permit that. |
| 5350 | |
| 5351 | @end table |
| 5352 | If you omit @var{style}, you will see a list of possible formats. |
| 5353 | |
| 5354 | @kindex show demangle-style |
| 5355 | @item show demangle-style |
| 5356 | Display the encoding style currently in use for decoding C@t{++} symbols. |
| 5357 | |
| 5358 | @kindex set print object |
| 5359 | @item set print object |
| 5360 | @itemx set print object on |
| 5361 | When displaying a pointer to an object, identify the @emph{actual} |
| 5362 | (derived) type of the object rather than the @emph{declared} type, using |
| 5363 | the virtual function table. |
| 5364 | |
| 5365 | @item set print object off |
| 5366 | Display only the declared type of objects, without reference to the |
| 5367 | virtual function table. This is the default setting. |
| 5368 | |
| 5369 | @kindex show print object |
| 5370 | @item show print object |
| 5371 | Show whether actual, or declared, object types are displayed. |
| 5372 | |
| 5373 | @kindex set print static-members |
| 5374 | @item set print static-members |
| 5375 | @itemx set print static-members on |
| 5376 | Print static members when displaying a C@t{++} object. The default is on. |
| 5377 | |
| 5378 | @item set print static-members off |
| 5379 | Do not print static members when displaying a C@t{++} object. |
| 5380 | |
| 5381 | @kindex show print static-members |
| 5382 | @item show print static-members |
| 5383 | Show whether C@t{++} static members are printed, or not. |
| 5384 | |
| 5385 | @c These don't work with HP ANSI C++ yet. |
| 5386 | @kindex set print vtbl |
| 5387 | @item set print vtbl |
| 5388 | @itemx set print vtbl on |
| 5389 | Pretty print C@t{++} virtual function tables. The default is off. |
| 5390 | (The @code{vtbl} commands do not work on programs compiled with the HP |
| 5391 | ANSI C@t{++} compiler (@code{aCC}).) |
| 5392 | |
| 5393 | @item set print vtbl off |
| 5394 | Do not pretty print C@t{++} virtual function tables. |
| 5395 | |
| 5396 | @kindex show print vtbl |
| 5397 | @item show print vtbl |
| 5398 | Show whether C@t{++} virtual function tables are pretty printed, or not. |
| 5399 | @end table |
| 5400 | |
| 5401 | @node Value History |
| 5402 | @section Value history |
| 5403 | |
| 5404 | @cindex value history |
| 5405 | Values printed by the @code{print} command are saved in the @value{GDBN} |
| 5406 | @dfn{value history}. This allows you to refer to them in other expressions. |
| 5407 | Values are kept until the symbol table is re-read or discarded |
| 5408 | (for example with the @code{file} or @code{symbol-file} commands). |
| 5409 | When the symbol table changes, the value history is discarded, |
| 5410 | since the values may contain pointers back to the types defined in the |
| 5411 | symbol table. |
| 5412 | |
| 5413 | @cindex @code{$} |
| 5414 | @cindex @code{$$} |
| 5415 | @cindex history number |
| 5416 | The values printed are given @dfn{history numbers} by which you can |
| 5417 | refer to them. These are successive integers starting with one. |
| 5418 | @code{print} shows you the history number assigned to a value by |
| 5419 | printing @samp{$@var{num} = } before the value; here @var{num} is the |
| 5420 | history number. |
| 5421 | |
| 5422 | To refer to any previous value, use @samp{$} followed by the value's |
| 5423 | history number. The way @code{print} labels its output is designed to |
| 5424 | remind you of this. Just @code{$} refers to the most recent value in |
| 5425 | the history, and @code{$$} refers to the value before that. |
| 5426 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} |
| 5427 | is the value just prior to @code{$$}, @code{$$1} is equivalent to |
| 5428 | @code{$$}, and @code{$$0} is equivalent to @code{$}. |
| 5429 | |
| 5430 | For example, suppose you have just printed a pointer to a structure and |
| 5431 | want to see the contents of the structure. It suffices to type |
| 5432 | |
| 5433 | @smallexample |
| 5434 | p *$ |
| 5435 | @end smallexample |
| 5436 | |
| 5437 | If you have a chain of structures where the component @code{next} points |
| 5438 | to the next one, you can print the contents of the next one with this: |
| 5439 | |
| 5440 | @smallexample |
| 5441 | p *$.next |
| 5442 | @end smallexample |
| 5443 | |
| 5444 | @noindent |
| 5445 | You can print successive links in the chain by repeating this |
| 5446 | command---which you can do by just typing @key{RET}. |
| 5447 | |
| 5448 | Note that the history records values, not expressions. If the value of |
| 5449 | @code{x} is 4 and you type these commands: |
| 5450 | |
| 5451 | @smallexample |
| 5452 | print x |
| 5453 | set x=5 |
| 5454 | @end smallexample |
| 5455 | |
| 5456 | @noindent |
| 5457 | then the value recorded in the value history by the @code{print} command |
| 5458 | remains 4 even though the value of @code{x} has changed. |
| 5459 | |
| 5460 | @table @code |
| 5461 | @kindex show values |
| 5462 | @item show values |
| 5463 | Print the last ten values in the value history, with their item numbers. |
| 5464 | This is like @samp{p@ $$9} repeated ten times, except that @code{show |
| 5465 | values} does not change the history. |
| 5466 | |
| 5467 | @item show values @var{n} |
| 5468 | Print ten history values centered on history item number @var{n}. |
| 5469 | |
| 5470 | @item show values + |
| 5471 | Print ten history values just after the values last printed. If no more |
| 5472 | values are available, @code{show values +} produces no display. |
| 5473 | @end table |
| 5474 | |
| 5475 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the |
| 5476 | same effect as @samp{show values +}. |
| 5477 | |
| 5478 | @node Convenience Vars |
| 5479 | @section Convenience variables |
| 5480 | |
| 5481 | @cindex convenience variables |
| 5482 | @value{GDBN} provides @dfn{convenience variables} that you can use within |
| 5483 | @value{GDBN} to hold on to a value and refer to it later. These variables |
| 5484 | exist entirely within @value{GDBN}; they are not part of your program, and |
| 5485 | setting a convenience variable has no direct effect on further execution |
| 5486 | of your program. That is why you can use them freely. |
| 5487 | |
| 5488 | Convenience variables are prefixed with @samp{$}. Any name preceded by |
| 5489 | @samp{$} can be used for a convenience variable, unless it is one of |
| 5490 | the predefined machine-specific register names (@pxref{Registers, ,Registers}). |
| 5491 | (Value history references, in contrast, are @emph{numbers} preceded |
| 5492 | by @samp{$}. @xref{Value History, ,Value history}.) |
| 5493 | |
| 5494 | You can save a value in a convenience variable with an assignment |
| 5495 | expression, just as you would set a variable in your program. |
| 5496 | For example: |
| 5497 | |
| 5498 | @smallexample |
| 5499 | set $foo = *object_ptr |
| 5500 | @end smallexample |
| 5501 | |
| 5502 | @noindent |
| 5503 | would save in @code{$foo} the value contained in the object pointed to by |
| 5504 | @code{object_ptr}. |
| 5505 | |
| 5506 | Using a convenience variable for the first time creates it, but its |
| 5507 | value is @code{void} until you assign a new value. You can alter the |
| 5508 | value with another assignment at any time. |
| 5509 | |
| 5510 | Convenience variables have no fixed types. You can assign a convenience |
| 5511 | variable any type of value, including structures and arrays, even if |
| 5512 | that variable already has a value of a different type. The convenience |
| 5513 | variable, when used as an expression, has the type of its current value. |
| 5514 | |
| 5515 | @table @code |
| 5516 | @kindex show convenience |
| 5517 | @item show convenience |
| 5518 | Print a list of convenience variables used so far, and their values. |
| 5519 | Abbreviated @code{show conv}. |
| 5520 | @end table |
| 5521 | |
| 5522 | One of the ways to use a convenience variable is as a counter to be |
| 5523 | incremented or a pointer to be advanced. For example, to print |
| 5524 | a field from successive elements of an array of structures: |
| 5525 | |
| 5526 | @smallexample |
| 5527 | set $i = 0 |
| 5528 | print bar[$i++]->contents |
| 5529 | @end smallexample |
| 5530 | |
| 5531 | @noindent |
| 5532 | Repeat that command by typing @key{RET}. |
| 5533 | |
| 5534 | Some convenience variables are created automatically by @value{GDBN} and given |
| 5535 | values likely to be useful. |
| 5536 | |
| 5537 | @table @code |
| 5538 | @vindex $_@r{, convenience variable} |
| 5539 | @item $_ |
| 5540 | The variable @code{$_} is automatically set by the @code{x} command to |
| 5541 | the last address examined (@pxref{Memory, ,Examining memory}). Other |
| 5542 | commands which provide a default address for @code{x} to examine also |
| 5543 | set @code{$_} to that address; these commands include @code{info line} |
| 5544 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} |
| 5545 | except when set by the @code{x} command, in which case it is a pointer |
| 5546 | to the type of @code{$__}. |
| 5547 | |
| 5548 | @vindex $__@r{, convenience variable} |
| 5549 | @item $__ |
| 5550 | The variable @code{$__} is automatically set by the @code{x} command |
| 5551 | to the value found in the last address examined. Its type is chosen |
| 5552 | to match the format in which the data was printed. |
| 5553 | |
| 5554 | @item $_exitcode |
| 5555 | @vindex $_exitcode@r{, convenience variable} |
| 5556 | The variable @code{$_exitcode} is automatically set to the exit code when |
| 5557 | the program being debugged terminates. |
| 5558 | @end table |
| 5559 | |
| 5560 | On HP-UX systems, if you refer to a function or variable name that |
| 5561 | begins with a dollar sign, @value{GDBN} searches for a user or system |
| 5562 | name first, before it searches for a convenience variable. |
| 5563 | |
| 5564 | @node Registers |
| 5565 | @section Registers |
| 5566 | |
| 5567 | @cindex registers |
| 5568 | You can refer to machine register contents, in expressions, as variables |
| 5569 | with names starting with @samp{$}. The names of registers are different |
| 5570 | for each machine; use @code{info registers} to see the names used on |
| 5571 | your machine. |
| 5572 | |
| 5573 | @table @code |
| 5574 | @kindex info registers |
| 5575 | @item info registers |
| 5576 | Print the names and values of all registers except floating-point |
| 5577 | and vector registers (in the selected stack frame). |
| 5578 | |
| 5579 | @kindex info all-registers |
| 5580 | @cindex floating point registers |
| 5581 | @item info all-registers |
| 5582 | Print the names and values of all registers, including floating-point |
| 5583 | and vector registers (in the selected stack frame). |
| 5584 | |
| 5585 | @item info registers @var{regname} @dots{} |
| 5586 | Print the @dfn{relativized} value of each specified register @var{regname}. |
| 5587 | As discussed in detail below, register values are normally relative to |
| 5588 | the selected stack frame. @var{regname} may be any register name valid on |
| 5589 | the machine you are using, with or without the initial @samp{$}. |
| 5590 | @end table |
| 5591 | |
| 5592 | @value{GDBN} has four ``standard'' register names that are available (in |
| 5593 | expressions) on most machines---whenever they do not conflict with an |
| 5594 | architecture's canonical mnemonics for registers. The register names |
| 5595 | @code{$pc} and @code{$sp} are used for the program counter register and |
| 5596 | the stack pointer. @code{$fp} is used for a register that contains a |
| 5597 | pointer to the current stack frame, and @code{$ps} is used for a |
| 5598 | register that contains the processor status. For example, |
| 5599 | you could print the program counter in hex with |
| 5600 | |
| 5601 | @smallexample |
| 5602 | p/x $pc |
| 5603 | @end smallexample |
| 5604 | |
| 5605 | @noindent |
| 5606 | or print the instruction to be executed next with |
| 5607 | |
| 5608 | @smallexample |
| 5609 | x/i $pc |
| 5610 | @end smallexample |
| 5611 | |
| 5612 | @noindent |
| 5613 | or add four to the stack pointer@footnote{This is a way of removing |
| 5614 | one word from the stack, on machines where stacks grow downward in |
| 5615 | memory (most machines, nowadays). This assumes that the innermost |
| 5616 | stack frame is selected; setting @code{$sp} is not allowed when other |
| 5617 | stack frames are selected. To pop entire frames off the stack, |
| 5618 | regardless of machine architecture, use @code{return}; |
| 5619 | see @ref{Returning, ,Returning from a function}.} with |
| 5620 | |
| 5621 | @smallexample |
| 5622 | set $sp += 4 |
| 5623 | @end smallexample |
| 5624 | |
| 5625 | Whenever possible, these four standard register names are available on |
| 5626 | your machine even though the machine has different canonical mnemonics, |
| 5627 | so long as there is no conflict. The @code{info registers} command |
| 5628 | shows the canonical names. For example, on the SPARC, @code{info |
| 5629 | registers} displays the processor status register as @code{$psr} but you |
| 5630 | can also refer to it as @code{$ps}; and on x86-based machines @code{$ps} |
| 5631 | is an alias for the @sc{eflags} register. |
| 5632 | |
| 5633 | @value{GDBN} always considers the contents of an ordinary register as an |
| 5634 | integer when the register is examined in this way. Some machines have |
| 5635 | special registers which can hold nothing but floating point; these |
| 5636 | registers are considered to have floating point values. There is no way |
| 5637 | to refer to the contents of an ordinary register as floating point value |
| 5638 | (although you can @emph{print} it as a floating point value with |
| 5639 | @samp{print/f $@var{regname}}). |
| 5640 | |
| 5641 | Some registers have distinct ``raw'' and ``virtual'' data formats. This |
| 5642 | means that the data format in which the register contents are saved by |
| 5643 | the operating system is not the same one that your program normally |
| 5644 | sees. For example, the registers of the 68881 floating point |
| 5645 | coprocessor are always saved in ``extended'' (raw) format, but all C |
| 5646 | programs expect to work with ``double'' (virtual) format. In such |
| 5647 | cases, @value{GDBN} normally works with the virtual format only (the format |
| 5648 | that makes sense for your program), but the @code{info registers} command |
| 5649 | prints the data in both formats. |
| 5650 | |
| 5651 | Normally, register values are relative to the selected stack frame |
| 5652 | (@pxref{Selection, ,Selecting a frame}). This means that you get the |
| 5653 | value that the register would contain if all stack frames farther in |
| 5654 | were exited and their saved registers restored. In order to see the |
| 5655 | true contents of hardware registers, you must select the innermost |
| 5656 | frame (with @samp{frame 0}). |
| 5657 | |
| 5658 | However, @value{GDBN} must deduce where registers are saved, from the machine |
| 5659 | code generated by your compiler. If some registers are not saved, or if |
| 5660 | @value{GDBN} is unable to locate the saved registers, the selected stack |
| 5661 | frame makes no difference. |
| 5662 | |
| 5663 | @node Floating Point Hardware |
| 5664 | @section Floating point hardware |
| 5665 | @cindex floating point |
| 5666 | |
| 5667 | Depending on the configuration, @value{GDBN} may be able to give |
| 5668 | you more information about the status of the floating point hardware. |
| 5669 | |
| 5670 | @table @code |
| 5671 | @kindex info float |
| 5672 | @item info float |
| 5673 | Display hardware-dependent information about the floating |
| 5674 | point unit. The exact contents and layout vary depending on the |
| 5675 | floating point chip. Currently, @samp{info float} is supported on |
| 5676 | the ARM and x86 machines. |
| 5677 | @end table |
| 5678 | |
| 5679 | @node Vector Unit |
| 5680 | @section Vector Unit |
| 5681 | @cindex vector unit |
| 5682 | |
| 5683 | Depending on the configuration, @value{GDBN} may be able to give you |
| 5684 | more information about the status of the vector unit. |
| 5685 | |
| 5686 | @table @code |
| 5687 | @kindex info vector |
| 5688 | @item info vector |
| 5689 | Display information about the vector unit. The exact contents and |
| 5690 | layout vary depending on the hardware. |
| 5691 | @end table |
| 5692 | |
| 5693 | @node Memory Region Attributes |
| 5694 | @section Memory region attributes |
| 5695 | @cindex memory region attributes |
| 5696 | |
| 5697 | @dfn{Memory region attributes} allow you to describe special handling |
| 5698 | required by regions of your target's memory. @value{GDBN} uses attributes |
| 5699 | to determine whether to allow certain types of memory accesses; whether to |
| 5700 | use specific width accesses; and whether to cache target memory. |
| 5701 | |
| 5702 | Defined memory regions can be individually enabled and disabled. When a |
| 5703 | memory region is disabled, @value{GDBN} uses the default attributes when |
| 5704 | accessing memory in that region. Similarly, if no memory regions have |
| 5705 | been defined, @value{GDBN} uses the default attributes when accessing |
| 5706 | all memory. |
| 5707 | |
| 5708 | When a memory region is defined, it is given a number to identify it; |
| 5709 | to enable, disable, or remove a memory region, you specify that number. |
| 5710 | |
| 5711 | @table @code |
| 5712 | @kindex mem |
| 5713 | @item mem @var{lower} @var{upper} @var{attributes}@dots{} |
| 5714 | Define memory region bounded by @var{lower} and @var{upper} with |
| 5715 | attributes @var{attributes}@dots{}. Note that @var{upper} == 0 is a |
| 5716 | special case: it is treated as the the target's maximum memory address. |
| 5717 | (0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.) |
| 5718 | |
| 5719 | @kindex delete mem |
| 5720 | @item delete mem @var{nums}@dots{} |
| 5721 | Remove memory regions @var{nums}@dots{}. |
| 5722 | |
| 5723 | @kindex disable mem |
| 5724 | @item disable mem @var{nums}@dots{} |
| 5725 | Disable memory regions @var{nums}@dots{}. |
| 5726 | A disabled memory region is not forgotten. |
| 5727 | It may be enabled again later. |
| 5728 | |
| 5729 | @kindex enable mem |
| 5730 | @item enable mem @var{nums}@dots{} |
| 5731 | Enable memory regions @var{nums}@dots{}. |
| 5732 | |
| 5733 | @kindex info mem |
| 5734 | @item info mem |
| 5735 | Print a table of all defined memory regions, with the following columns |
| 5736 | for each region. |
| 5737 | |
| 5738 | @table @emph |
| 5739 | @item Memory Region Number |
| 5740 | @item Enabled or Disabled. |
| 5741 | Enabled memory regions are marked with @samp{y}. |
| 5742 | Disabled memory regions are marked with @samp{n}. |
| 5743 | |
| 5744 | @item Lo Address |
| 5745 | The address defining the inclusive lower bound of the memory region. |
| 5746 | |
| 5747 | @item Hi Address |
| 5748 | The address defining the exclusive upper bound of the memory region. |
| 5749 | |
| 5750 | @item Attributes |
| 5751 | The list of attributes set for this memory region. |
| 5752 | @end table |
| 5753 | @end table |
| 5754 | |
| 5755 | |
| 5756 | @subsection Attributes |
| 5757 | |
| 5758 | @subsubsection Memory Access Mode |
| 5759 | The access mode attributes set whether @value{GDBN} may make read or |
| 5760 | write accesses to a memory region. |
| 5761 | |
| 5762 | While these attributes prevent @value{GDBN} from performing invalid |
| 5763 | memory accesses, they do nothing to prevent the target system, I/O DMA, |
| 5764 | etc. from accessing memory. |
| 5765 | |
| 5766 | @table @code |
| 5767 | @item ro |
| 5768 | Memory is read only. |
| 5769 | @item wo |
| 5770 | Memory is write only. |
| 5771 | @item rw |
| 5772 | Memory is read/write. This is the default. |
| 5773 | @end table |
| 5774 | |
| 5775 | @subsubsection Memory Access Size |
| 5776 | The acccess size attributes tells @value{GDBN} to use specific sized |
| 5777 | accesses in the memory region. Often memory mapped device registers |
| 5778 | require specific sized accesses. If no access size attribute is |
| 5779 | specified, @value{GDBN} may use accesses of any size. |
| 5780 | |
| 5781 | @table @code |
| 5782 | @item 8 |
| 5783 | Use 8 bit memory accesses. |
| 5784 | @item 16 |
| 5785 | Use 16 bit memory accesses. |
| 5786 | @item 32 |
| 5787 | Use 32 bit memory accesses. |
| 5788 | @item 64 |
| 5789 | Use 64 bit memory accesses. |
| 5790 | @end table |
| 5791 | |
| 5792 | @c @subsubsection Hardware/Software Breakpoints |
| 5793 | @c The hardware/software breakpoint attributes set whether @value{GDBN} |
| 5794 | @c will use hardware or software breakpoints for the internal breakpoints |
| 5795 | @c used by the step, next, finish, until, etc. commands. |
| 5796 | @c |
| 5797 | @c @table @code |
| 5798 | @c @item hwbreak |
| 5799 | @c Always use hardware breakpoints |
| 5800 | @c @item swbreak (default) |
| 5801 | @c @end table |
| 5802 | |
| 5803 | @subsubsection Data Cache |
| 5804 | The data cache attributes set whether @value{GDBN} will cache target |
| 5805 | memory. While this generally improves performance by reducing debug |
| 5806 | protocol overhead, it can lead to incorrect results because @value{GDBN} |
| 5807 | does not know about volatile variables or memory mapped device |
| 5808 | registers. |
| 5809 | |
| 5810 | @table @code |
| 5811 | @item cache |
| 5812 | Enable @value{GDBN} to cache target memory. |
| 5813 | @item nocache |
| 5814 | Disable @value{GDBN} from caching target memory. This is the default. |
| 5815 | @end table |
| 5816 | |
| 5817 | @c @subsubsection Memory Write Verification |
| 5818 | @c The memory write verification attributes set whether @value{GDBN} |
| 5819 | @c will re-reads data after each write to verify the write was successful. |
| 5820 | @c |
| 5821 | @c @table @code |
| 5822 | @c @item verify |
| 5823 | @c @item noverify (default) |
| 5824 | @c @end table |
| 5825 | |
| 5826 | @node Dump/Restore Files |
| 5827 | @section Copy between memory and a file |
| 5828 | @cindex dump/restore files |
| 5829 | @cindex append data to a file |
| 5830 | @cindex dump data to a file |
| 5831 | @cindex restore data from a file |
| 5832 | @kindex dump |
| 5833 | @kindex append |
| 5834 | @kindex restore |
| 5835 | |
| 5836 | The commands @code{dump}, @code{append}, and @code{restore} are used |
| 5837 | for copying data between target memory and a file. Data is written |
| 5838 | into a file using @code{dump} or @code{append}, and restored from a |
| 5839 | file into memory by using @code{restore}. Files may be binary, srec, |
| 5840 | intel hex, or tekhex (but only binary files can be appended). |
| 5841 | |
| 5842 | @table @code |
| 5843 | @kindex dump binary |
| 5844 | @kindex append binary |
| 5845 | @item dump binary memory @var{filename} @var{start_addr} @var{end_addr} |
| 5846 | Dump contents of memory from @var{start_addr} to @var{end_addr} into |
| 5847 | raw binary format file @var{filename}. |
| 5848 | |
| 5849 | @item append binary memory @var{filename} @var{start_addr} @var{end_addr} |
| 5850 | Append contents of memory from @var{start_addr} to @var{end_addr} to |
| 5851 | raw binary format file @var{filename}. |
| 5852 | |
| 5853 | @item dump binary value @var{filename} @var{expression} |
| 5854 | Dump value of @var{expression} into raw binary format file @var{filename}. |
| 5855 | |
| 5856 | @item append binary memory @var{filename} @var{expression} |
| 5857 | Append value of @var{expression} to raw binary format file @var{filename}. |
| 5858 | |
| 5859 | @kindex dump ihex |
| 5860 | @item dump ihex memory @var{filename} @var{start_addr} @var{end_addr} |
| 5861 | Dump contents of memory from @var{start_addr} to @var{end_addr} into |
| 5862 | intel hex format file @var{filename}. |
| 5863 | |
| 5864 | @item dump ihex value @var{filename} @var{expression} |
| 5865 | Dump value of @var{expression} into intel hex format file @var{filename}. |
| 5866 | |
| 5867 | @kindex dump srec |
| 5868 | @item dump srec memory @var{filename} @var{start_addr} @var{end_addr} |
| 5869 | Dump contents of memory from @var{start_addr} to @var{end_addr} into |
| 5870 | srec format file @var{filename}. |
| 5871 | |
| 5872 | @item dump srec value @var{filename} @var{expression} |
| 5873 | Dump value of @var{expression} into srec format file @var{filename}. |
| 5874 | |
| 5875 | @kindex dump tekhex |
| 5876 | @item dump tekhex memory @var{filename} @var{start_addr} @var{end_addr} |
| 5877 | Dump contents of memory from @var{start_addr} to @var{end_addr} into |
| 5878 | tekhex format file @var{filename}. |
| 5879 | |
| 5880 | @item dump tekhex value @var{filename} @var{expression} |
| 5881 | Dump value of @var{expression} into tekhex format file @var{filename}. |
| 5882 | |
| 5883 | @item restore @var{filename} [@var{binary}] @var{bias} @var{start} @var{end} |
| 5884 | Restore the contents of file @var{filename} into memory. The @code{restore} |
| 5885 | command can automatically recognize any known bfd file format, except for |
| 5886 | raw binary. To restore a raw binary file you must use the optional argument |
| 5887 | @var{binary} after the filename. |
| 5888 | |
| 5889 | If @var{bias} is non-zero, its value will be added to the addresses |
| 5890 | contained in the file. Binary files always start at address zero, so |
| 5891 | they will be restored at address @var{bias}. Other bfd files have |
| 5892 | a built-in location; they will be restored at offset @var{bias} |
| 5893 | from that location. |
| 5894 | |
| 5895 | If @var{start} and/or @var{end} are non-zero, then only data between |
| 5896 | file offset @var{start} and file offset @var{end} will be restored. |
| 5897 | These offsets are relative to the addresses in the file, before |
| 5898 | the @var{bias} argument is applied. |
| 5899 | |
| 5900 | @end table |
| 5901 | |
| 5902 | @node Character Sets |
| 5903 | @section Character Sets |
| 5904 | @cindex character sets |
| 5905 | @cindex charset |
| 5906 | @cindex translating between character sets |
| 5907 | @cindex host character set |
| 5908 | @cindex target character set |
| 5909 | |
| 5910 | If the program you are debugging uses a different character set to |
| 5911 | represent characters and strings than the one @value{GDBN} uses itself, |
| 5912 | @value{GDBN} can automatically translate between the character sets for |
| 5913 | you. The character set @value{GDBN} uses we call the @dfn{host |
| 5914 | character set}; the one the inferior program uses we call the |
| 5915 | @dfn{target character set}. |
| 5916 | |
| 5917 | For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which |
| 5918 | uses the ISO Latin 1 character set, but you are using @value{GDBN}'s |
| 5919 | remote protocol (@pxref{Remote,Remote Debugging}) to debug a program |
| 5920 | running on an IBM mainframe, which uses the @sc{ebcdic} character set, |
| 5921 | then the host character set is Latin-1, and the target character set is |
| 5922 | @sc{ebcdic}. If you give @value{GDBN} the command @code{set |
| 5923 | target-charset ebcdic-us}, then @value{GDBN} translates between |
| 5924 | @sc{ebcdic} and Latin 1 as you print character or string values, or use |
| 5925 | character and string literals in expressions. |
| 5926 | |
| 5927 | @value{GDBN} has no way to automatically recognize which character set |
| 5928 | the inferior program uses; you must tell it, using the @code{set |
| 5929 | target-charset} command, described below. |
| 5930 | |
| 5931 | Here are the commands for controlling @value{GDBN}'s character set |
| 5932 | support: |
| 5933 | |
| 5934 | @table @code |
| 5935 | @item set target-charset @var{charset} |
| 5936 | @kindex set target-charset |
| 5937 | Set the current target character set to @var{charset}. We list the |
| 5938 | character set names @value{GDBN} recognizes below, but if you invoke the |
| 5939 | @code{set target-charset} command with no argument, @value{GDBN} lists |
| 5940 | the character sets it supports. |
| 5941 | @end table |
| 5942 | |
| 5943 | @table @code |
| 5944 | @item set host-charset @var{charset} |
| 5945 | @kindex set host-charset |
| 5946 | Set the current host character set to @var{charset}. |
| 5947 | |
| 5948 | By default, @value{GDBN} uses a host character set appropriate to the |
| 5949 | system it is running on; you can override that default using the |
| 5950 | @code{set host-charset} command. |
| 5951 | |
| 5952 | @value{GDBN} can only use certain character sets as its host character |
| 5953 | set. We list the character set names @value{GDBN} recognizes below, and |
| 5954 | indicate which can be host character sets, but if you invoke the |
| 5955 | @code{set host-charset} command with no argument, @value{GDBN} lists the |
| 5956 | character sets it supports, placing an asterisk (@samp{*}) after those |
| 5957 | it can use as a host character set. |
| 5958 | |
| 5959 | @item set charset @var{charset} |
| 5960 | @kindex set charset |
| 5961 | Set the current host and target character sets to @var{charset}. If you |
| 5962 | invoke the @code{set charset} command with no argument, it lists the |
| 5963 | character sets it supports. @value{GDBN} can only use certain character |
| 5964 | sets as its host character set; it marks those in the list with an |
| 5965 | asterisk (@samp{*}). |
| 5966 | |
| 5967 | @item show charset |
| 5968 | @itemx show host-charset |
| 5969 | @itemx show target-charset |
| 5970 | @kindex show charset |
| 5971 | @kindex show host-charset |
| 5972 | @kindex show target-charset |
| 5973 | Show the current host and target charsets. The @code{show host-charset} |
| 5974 | and @code{show target-charset} commands are synonyms for @code{show |
| 5975 | charset}. |
| 5976 | |
| 5977 | @end table |
| 5978 | |
| 5979 | @value{GDBN} currently includes support for the following character |
| 5980 | sets: |
| 5981 | |
| 5982 | @table @code |
| 5983 | |
| 5984 | @item ASCII |
| 5985 | @cindex ASCII character set |
| 5986 | Seven-bit U.S. @sc{ascii}. @value{GDBN} can use this as its host |
| 5987 | character set. |
| 5988 | |
| 5989 | @item ISO-8859-1 |
| 5990 | @cindex ISO 8859-1 character set |
| 5991 | @cindex ISO Latin 1 character set |
| 5992 | The ISO Latin 1 character set. This extends ASCII with accented |
| 5993 | characters needed for French, German, and Spanish. @value{GDBN} can use |
| 5994 | this as its host character set. |
| 5995 | |
| 5996 | @item EBCDIC-US |
| 5997 | @itemx IBM1047 |
| 5998 | @cindex EBCDIC character set |
| 5999 | @cindex IBM1047 character set |
| 6000 | Variants of the @sc{ebcdic} character set, used on some of IBM's |
| 6001 | mainframe operating systems. (@sc{gnu}/Linux on the S/390 uses U.S. @sc{ascii}.) |
| 6002 | @value{GDBN} cannot use these as its host character set. |
| 6003 | |
| 6004 | @end table |
| 6005 | |
| 6006 | Note that these are all single-byte character sets. More work inside |
| 6007 | GDB is needed to support multi-byte or variable-width character |
| 6008 | encodings, like the UTF-8 and UCS-2 encodings of Unicode. |
| 6009 | |
| 6010 | Here is an example of @value{GDBN}'s character set support in action. |
| 6011 | Assume that the following source code has been placed in the file |
| 6012 | @file{charset-test.c}: |
| 6013 | |
| 6014 | @smallexample |
| 6015 | #include <stdio.h> |
| 6016 | |
| 6017 | char ascii_hello[] |
| 6018 | = @{72, 101, 108, 108, 111, 44, 32, 119, |
| 6019 | 111, 114, 108, 100, 33, 10, 0@}; |
| 6020 | char ibm1047_hello[] |
| 6021 | = @{200, 133, 147, 147, 150, 107, 64, 166, |
| 6022 | 150, 153, 147, 132, 90, 37, 0@}; |
| 6023 | |
| 6024 | main () |
| 6025 | @{ |
| 6026 | printf ("Hello, world!\n"); |
| 6027 | @} |
| 6028 | @end smallexample |
| 6029 | |
| 6030 | In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays |
| 6031 | containing the string @samp{Hello, world!} followed by a newline, |
| 6032 | encoded in the @sc{ascii} and @sc{ibm1047} character sets. |
| 6033 | |
| 6034 | We compile the program, and invoke the debugger on it: |
| 6035 | |
| 6036 | @smallexample |
| 6037 | $ gcc -g charset-test.c -o charset-test |
| 6038 | $ gdb -nw charset-test |
| 6039 | GNU gdb 2001-12-19-cvs |
| 6040 | Copyright 2001 Free Software Foundation, Inc. |
| 6041 | @dots{} |
| 6042 | (gdb) |
| 6043 | @end smallexample |
| 6044 | |
| 6045 | We can use the @code{show charset} command to see what character sets |
| 6046 | @value{GDBN} is currently using to interpret and display characters and |
| 6047 | strings: |
| 6048 | |
| 6049 | @smallexample |
| 6050 | (gdb) show charset |
| 6051 | The current host and target character set is `iso-8859-1'. |
| 6052 | (gdb) |
| 6053 | @end smallexample |
| 6054 | |
| 6055 | For the sake of printing this manual, let's use @sc{ascii} as our |
| 6056 | initial character set: |
| 6057 | @smallexample |
| 6058 | (gdb) set charset ascii |
| 6059 | (gdb) show charset |
| 6060 | The current host and target character set is `ascii'. |
| 6061 | (gdb) |
| 6062 | @end smallexample |
| 6063 | |
| 6064 | Let's assume that @sc{ascii} is indeed the correct character set for our |
| 6065 | host system --- in other words, let's assume that if @value{GDBN} prints |
| 6066 | characters using the @sc{ascii} character set, our terminal will display |
| 6067 | them properly. Since our current target character set is also |
| 6068 | @sc{ascii}, the contents of @code{ascii_hello} print legibly: |
| 6069 | |
| 6070 | @smallexample |
| 6071 | (gdb) print ascii_hello |
| 6072 | $1 = 0x401698 "Hello, world!\n" |
| 6073 | (gdb) print ascii_hello[0] |
| 6074 | $2 = 72 'H' |
| 6075 | (gdb) |
| 6076 | @end smallexample |
| 6077 | |
| 6078 | @value{GDBN} uses the target character set for character and string |
| 6079 | literals you use in expressions: |
| 6080 | |
| 6081 | @smallexample |
| 6082 | (gdb) print '+' |
| 6083 | $3 = 43 '+' |
| 6084 | (gdb) |
| 6085 | @end smallexample |
| 6086 | |
| 6087 | The @sc{ascii} character set uses the number 43 to encode the @samp{+} |
| 6088 | character. |
| 6089 | |
| 6090 | @value{GDBN} relies on the user to tell it which character set the |
| 6091 | target program uses. If we print @code{ibm1047_hello} while our target |
| 6092 | character set is still @sc{ascii}, we get jibberish: |
| 6093 | |
| 6094 | @smallexample |
| 6095 | (gdb) print ibm1047_hello |
| 6096 | $4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%" |
| 6097 | (gdb) print ibm1047_hello[0] |
| 6098 | $5 = 200 '\310' |
| 6099 | (gdb) |
| 6100 | @end smallexample |
| 6101 | |
| 6102 | If we invoke the @code{set target-charset} command without an argument, |
| 6103 | @value{GDBN} tells us the character sets it supports: |
| 6104 | |
| 6105 | @smallexample |
| 6106 | (gdb) set target-charset |
| 6107 | Valid character sets are: |
| 6108 | ascii * |
| 6109 | iso-8859-1 * |
| 6110 | ebcdic-us |
| 6111 | ibm1047 |
| 6112 | * - can be used as a host character set |
| 6113 | @end smallexample |
| 6114 | |
| 6115 | We can select @sc{ibm1047} as our target character set, and examine the |
| 6116 | program's strings again. Now the @sc{ascii} string is wrong, but |
| 6117 | @value{GDBN} translates the contents of @code{ibm1047_hello} from the |
| 6118 | target character set, @sc{ibm1047}, to the host character set, |
| 6119 | @sc{ascii}, and they display correctly: |
| 6120 | |
| 6121 | @smallexample |
| 6122 | (gdb) set target-charset ibm1047 |
| 6123 | (gdb) show charset |
| 6124 | The current host character set is `ascii'. |
| 6125 | The current target character set is `ibm1047'. |
| 6126 | (gdb) print ascii_hello |
| 6127 | $6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012" |
| 6128 | (gdb) print ascii_hello[0] |
| 6129 | $7 = 72 '\110' |
| 6130 | (gdb) print ibm1047_hello |
| 6131 | $8 = 0x4016a8 "Hello, world!\n" |
| 6132 | (gdb) print ibm1047_hello[0] |
| 6133 | $9 = 200 'H' |
| 6134 | (gdb) |
| 6135 | @end smallexample |
| 6136 | |
| 6137 | As above, @value{GDBN} uses the target character set for character and |
| 6138 | string literals you use in expressions: |
| 6139 | |
| 6140 | @smallexample |
| 6141 | (gdb) print '+' |
| 6142 | $10 = 78 '+' |
| 6143 | (gdb) |
| 6144 | @end smallexample |
| 6145 | |
| 6146 | The IBM1047 character set uses the number 78 to encode the @samp{+} |
| 6147 | character. |
| 6148 | |
| 6149 | |
| 6150 | @node Macros |
| 6151 | @chapter C Preprocessor Macros |
| 6152 | |
| 6153 | Some languages, such as C and C++, provide a way to define and invoke |
| 6154 | ``preprocessor macros'' which expand into strings of tokens. |
| 6155 | @value{GDBN} can evaluate expressions containing macro invocations, show |
| 6156 | the result of macro expansion, and show a macro's definition, including |
| 6157 | where it was defined. |
| 6158 | |
| 6159 | You may need to compile your program specially to provide @value{GDBN} |
| 6160 | with information about preprocessor macros. Most compilers do not |
| 6161 | include macros in their debugging information, even when you compile |
| 6162 | with the @option{-g} flag. @xref{Compilation}. |
| 6163 | |
| 6164 | A program may define a macro at one point, remove that definition later, |
| 6165 | and then provide a different definition after that. Thus, at different |
| 6166 | points in the program, a macro may have different definitions, or have |
| 6167 | no definition at all. If there is a current stack frame, @value{GDBN} |
| 6168 | uses the macros in scope at that frame's source code line. Otherwise, |
| 6169 | @value{GDBN} uses the macros in scope at the current listing location; |
| 6170 | see @ref{List}. |
| 6171 | |
| 6172 | At the moment, @value{GDBN} does not support the @code{##} |
| 6173 | token-splicing operator, the @code{#} stringification operator, or |
| 6174 | variable-arity macros. |
| 6175 | |
| 6176 | Whenever @value{GDBN} evaluates an expression, it always expands any |
| 6177 | macro invocations present in the expression. @value{GDBN} also provides |
| 6178 | the following commands for working with macros explicitly. |
| 6179 | |
| 6180 | @table @code |
| 6181 | |
| 6182 | @kindex macro expand |
| 6183 | @cindex macro expansion, showing the results of preprocessor |
| 6184 | @cindex preprocessor macro expansion, showing the results of |
| 6185 | @cindex expanding preprocessor macros |
| 6186 | @item macro expand @var{expression} |
| 6187 | @itemx macro exp @var{expression} |
| 6188 | Show the results of expanding all preprocessor macro invocations in |
| 6189 | @var{expression}. Since @value{GDBN} simply expands macros, but does |
| 6190 | not parse the result, @var{expression} need not be a valid expression; |
| 6191 | it can be any string of tokens. |
| 6192 | |
| 6193 | @kindex macro expand-once |
| 6194 | @item macro expand-once @var{expression} |
| 6195 | @itemx macro exp1 @var{expression} |
| 6196 | @i{(This command is not yet implemented.)} Show the results of |
| 6197 | expanding those preprocessor macro invocations that appear explicitly in |
| 6198 | @var{expression}. Macro invocations appearing in that expansion are |
| 6199 | left unchanged. This command allows you to see the effect of a |
| 6200 | particular macro more clearly, without being confused by further |
| 6201 | expansions. Since @value{GDBN} simply expands macros, but does not |
| 6202 | parse the result, @var{expression} need not be a valid expression; it |
| 6203 | can be any string of tokens. |
| 6204 | |
| 6205 | @kindex info macro |
| 6206 | @cindex macro definition, showing |
| 6207 | @cindex definition, showing a macro's |
| 6208 | @item info macro @var{macro} |
| 6209 | Show the definition of the macro named @var{macro}, and describe the |
| 6210 | source location where that definition was established. |
| 6211 | |
| 6212 | @kindex macro define |
| 6213 | @cindex user-defined macros |
| 6214 | @cindex defining macros interactively |
| 6215 | @cindex macros, user-defined |
| 6216 | @item macro define @var{macro} @var{replacement-list} |
| 6217 | @itemx macro define @var{macro}(@var{arglist}) @var{replacement-list} |
| 6218 | @i{(This command is not yet implemented.)} Introduce a definition for a |
| 6219 | preprocessor macro named @var{macro}, invocations of which are replaced |
| 6220 | by the tokens given in @var{replacement-list}. The first form of this |
| 6221 | command defines an ``object-like'' macro, which takes no arguments; the |
| 6222 | second form defines a ``function-like'' macro, which takes the arguments |
| 6223 | given in @var{arglist}. |
| 6224 | |
| 6225 | A definition introduced by this command is in scope in every expression |
| 6226 | evaluated in @value{GDBN}, until it is removed with the @command{macro |
| 6227 | undef} command, described below. The definition overrides all |
| 6228 | definitions for @var{macro} present in the program being debugged, as |
| 6229 | well as any previous user-supplied definition. |
| 6230 | |
| 6231 | @kindex macro undef |
| 6232 | @item macro undef @var{macro} |
| 6233 | @i{(This command is not yet implemented.)} Remove any user-supplied |
| 6234 | definition for the macro named @var{macro}. This command only affects |
| 6235 | definitions provided with the @command{macro define} command, described |
| 6236 | above; it cannot remove definitions present in the program being |
| 6237 | debugged. |
| 6238 | |
| 6239 | @end table |
| 6240 | |
| 6241 | @cindex macros, example of debugging with |
| 6242 | Here is a transcript showing the above commands in action. First, we |
| 6243 | show our source files: |
| 6244 | |
| 6245 | @smallexample |
| 6246 | $ cat sample.c |
| 6247 | #include <stdio.h> |
| 6248 | #include "sample.h" |
| 6249 | |
| 6250 | #define M 42 |
| 6251 | #define ADD(x) (M + x) |
| 6252 | |
| 6253 | main () |
| 6254 | @{ |
| 6255 | #define N 28 |
| 6256 | printf ("Hello, world!\n"); |
| 6257 | #undef N |
| 6258 | printf ("We're so creative.\n"); |
| 6259 | #define N 1729 |
| 6260 | printf ("Goodbye, world!\n"); |
| 6261 | @} |
| 6262 | $ cat sample.h |
| 6263 | #define Q < |
| 6264 | $ |
| 6265 | @end smallexample |
| 6266 | |
| 6267 | Now, we compile the program using the @sc{gnu} C compiler, @value{NGCC}. |
| 6268 | We pass the @option{-gdwarf-2} and @option{-g3} flags to ensure the |
| 6269 | compiler includes information about preprocessor macros in the debugging |
| 6270 | information. |
| 6271 | |
| 6272 | @smallexample |
| 6273 | $ gcc -gdwarf-2 -g3 sample.c -o sample |
| 6274 | $ |
| 6275 | @end smallexample |
| 6276 | |
| 6277 | Now, we start @value{GDBN} on our sample program: |
| 6278 | |
| 6279 | @smallexample |
| 6280 | $ gdb -nw sample |
| 6281 | GNU gdb 2002-05-06-cvs |
| 6282 | Copyright 2002 Free Software Foundation, Inc. |
| 6283 | GDB is free software, @dots{} |
| 6284 | (gdb) |
| 6285 | @end smallexample |
| 6286 | |
| 6287 | We can expand macros and examine their definitions, even when the |
| 6288 | program is not running. @value{GDBN} uses the current listing position |
| 6289 | to decide which macro definitions are in scope: |
| 6290 | |
| 6291 | @smallexample |
| 6292 | (gdb) list main |
| 6293 | 3 |
| 6294 | 4 #define M 42 |
| 6295 | 5 #define ADD(x) (M + x) |
| 6296 | 6 |
| 6297 | 7 main () |
| 6298 | 8 @{ |
| 6299 | 9 #define N 28 |
| 6300 | 10 printf ("Hello, world!\n"); |
| 6301 | 11 #undef N |
| 6302 | 12 printf ("We're so creative.\n"); |
| 6303 | (gdb) info macro ADD |
| 6304 | Defined at /home/jimb/gdb/macros/play/sample.c:5 |
| 6305 | #define ADD(x) (M + x) |
| 6306 | (gdb) info macro Q |
| 6307 | Defined at /home/jimb/gdb/macros/play/sample.h:1 |
| 6308 | included at /home/jimb/gdb/macros/play/sample.c:2 |
| 6309 | #define Q < |
| 6310 | (gdb) macro expand ADD(1) |
| 6311 | expands to: (42 + 1) |
| 6312 | (gdb) macro expand-once ADD(1) |
| 6313 | expands to: once (M + 1) |
| 6314 | (gdb) |
| 6315 | @end smallexample |
| 6316 | |
| 6317 | In the example above, note that @command{macro expand-once} expands only |
| 6318 | the macro invocation explicit in the original text --- the invocation of |
| 6319 | @code{ADD} --- but does not expand the invocation of the macro @code{M}, |
| 6320 | which was introduced by @code{ADD}. |
| 6321 | |
| 6322 | Once the program is running, GDB uses the macro definitions in force at |
| 6323 | the source line of the current stack frame: |
| 6324 | |
| 6325 | @smallexample |
| 6326 | (gdb) break main |
| 6327 | Breakpoint 1 at 0x8048370: file sample.c, line 10. |
| 6328 | (gdb) run |
| 6329 | Starting program: /home/jimb/gdb/macros/play/sample |
| 6330 | |
| 6331 | Breakpoint 1, main () at sample.c:10 |
| 6332 | 10 printf ("Hello, world!\n"); |
| 6333 | (gdb) |
| 6334 | @end smallexample |
| 6335 | |
| 6336 | At line 10, the definition of the macro @code{N} at line 9 is in force: |
| 6337 | |
| 6338 | @smallexample |
| 6339 | (gdb) info macro N |
| 6340 | Defined at /home/jimb/gdb/macros/play/sample.c:9 |
| 6341 | #define N 28 |
| 6342 | (gdb) macro expand N Q M |
| 6343 | expands to: 28 < 42 |
| 6344 | (gdb) print N Q M |
| 6345 | $1 = 1 |
| 6346 | (gdb) |
| 6347 | @end smallexample |
| 6348 | |
| 6349 | As we step over directives that remove @code{N}'s definition, and then |
| 6350 | give it a new definition, @value{GDBN} finds the definition (or lack |
| 6351 | thereof) in force at each point: |
| 6352 | |
| 6353 | @smallexample |
| 6354 | (gdb) next |
| 6355 | Hello, world! |
| 6356 | 12 printf ("We're so creative.\n"); |
| 6357 | (gdb) info macro N |
| 6358 | The symbol `N' has no definition as a C/C++ preprocessor macro |
| 6359 | at /home/jimb/gdb/macros/play/sample.c:12 |
| 6360 | (gdb) next |
| 6361 | We're so creative. |
| 6362 | 14 printf ("Goodbye, world!\n"); |
| 6363 | (gdb) info macro N |
| 6364 | Defined at /home/jimb/gdb/macros/play/sample.c:13 |
| 6365 | #define N 1729 |
| 6366 | (gdb) macro expand N Q M |
| 6367 | expands to: 1729 < 42 |
| 6368 | (gdb) print N Q M |
| 6369 | $2 = 0 |
| 6370 | (gdb) |
| 6371 | @end smallexample |
| 6372 | |
| 6373 | |
| 6374 | @node Tracepoints |
| 6375 | @chapter Tracepoints |
| 6376 | @c This chapter is based on the documentation written by Michael |
| 6377 | @c Snyder, David Taylor, Jim Blandy, and Elena Zannoni. |
| 6378 | |
| 6379 | @cindex tracepoints |
| 6380 | In some applications, it is not feasible for the debugger to interrupt |
| 6381 | the program's execution long enough for the developer to learn |
| 6382 | anything helpful about its behavior. If the program's correctness |
| 6383 | depends on its real-time behavior, delays introduced by a debugger |
| 6384 | might cause the program to change its behavior drastically, or perhaps |
| 6385 | fail, even when the code itself is correct. It is useful to be able |
| 6386 | to observe the program's behavior without interrupting it. |
| 6387 | |
| 6388 | Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can |
| 6389 | specify locations in the program, called @dfn{tracepoints}, and |
| 6390 | arbitrary expressions to evaluate when those tracepoints are reached. |
| 6391 | Later, using the @code{tfind} command, you can examine the values |
| 6392 | those expressions had when the program hit the tracepoints. The |
| 6393 | expressions may also denote objects in memory---structures or arrays, |
| 6394 | for example---whose values @value{GDBN} should record; while visiting |
| 6395 | a particular tracepoint, you may inspect those objects as if they were |
| 6396 | in memory at that moment. However, because @value{GDBN} records these |
| 6397 | values without interacting with you, it can do so quickly and |
| 6398 | unobtrusively, hopefully not disturbing the program's behavior. |
| 6399 | |
| 6400 | The tracepoint facility is currently available only for remote |
| 6401 | targets. @xref{Targets}. In addition, your remote target must know how |
| 6402 | to collect trace data. This functionality is implemented in the remote |
| 6403 | stub; however, none of the stubs distributed with @value{GDBN} support |
| 6404 | tracepoints as of this writing. |
| 6405 | |
| 6406 | This chapter describes the tracepoint commands and features. |
| 6407 | |
| 6408 | @menu |
| 6409 | * Set Tracepoints:: |
| 6410 | * Analyze Collected Data:: |
| 6411 | * Tracepoint Variables:: |
| 6412 | @end menu |
| 6413 | |
| 6414 | @node Set Tracepoints |
| 6415 | @section Commands to Set Tracepoints |
| 6416 | |
| 6417 | Before running such a @dfn{trace experiment}, an arbitrary number of |
| 6418 | tracepoints can be set. Like a breakpoint (@pxref{Set Breaks}), a |
| 6419 | tracepoint has a number assigned to it by @value{GDBN}. Like with |
| 6420 | breakpoints, tracepoint numbers are successive integers starting from |
| 6421 | one. Many of the commands associated with tracepoints take the |
| 6422 | tracepoint number as their argument, to identify which tracepoint to |
| 6423 | work on. |
| 6424 | |
| 6425 | For each tracepoint, you can specify, in advance, some arbitrary set |
| 6426 | of data that you want the target to collect in the trace buffer when |
| 6427 | it hits that tracepoint. The collected data can include registers, |
| 6428 | local variables, or global data. Later, you can use @value{GDBN} |
| 6429 | commands to examine the values these data had at the time the |
| 6430 | tracepoint was hit. |
| 6431 | |
| 6432 | This section describes commands to set tracepoints and associated |
| 6433 | conditions and actions. |
| 6434 | |
| 6435 | @menu |
| 6436 | * Create and Delete Tracepoints:: |
| 6437 | * Enable and Disable Tracepoints:: |
| 6438 | * Tracepoint Passcounts:: |
| 6439 | * Tracepoint Actions:: |
| 6440 | * Listing Tracepoints:: |
| 6441 | * Starting and Stopping Trace Experiment:: |
| 6442 | @end menu |
| 6443 | |
| 6444 | @node Create and Delete Tracepoints |
| 6445 | @subsection Create and Delete Tracepoints |
| 6446 | |
| 6447 | @table @code |
| 6448 | @cindex set tracepoint |
| 6449 | @kindex trace |
| 6450 | @item trace |
| 6451 | The @code{trace} command is very similar to the @code{break} command. |
| 6452 | Its argument can be a source line, a function name, or an address in |
| 6453 | the target program. @xref{Set Breaks}. The @code{trace} command |
| 6454 | defines a tracepoint, which is a point in the target program where the |
| 6455 | debugger will briefly stop, collect some data, and then allow the |
| 6456 | program to continue. Setting a tracepoint or changing its commands |
| 6457 | doesn't take effect until the next @code{tstart} command; thus, you |
| 6458 | cannot change the tracepoint attributes once a trace experiment is |
| 6459 | running. |
| 6460 | |
| 6461 | Here are some examples of using the @code{trace} command: |
| 6462 | |
| 6463 | @smallexample |
| 6464 | (@value{GDBP}) @b{trace foo.c:121} // a source file and line number |
| 6465 | |
| 6466 | (@value{GDBP}) @b{trace +2} // 2 lines forward |
| 6467 | |
| 6468 | (@value{GDBP}) @b{trace my_function} // first source line of function |
| 6469 | |
| 6470 | (@value{GDBP}) @b{trace *my_function} // EXACT start address of function |
| 6471 | |
| 6472 | (@value{GDBP}) @b{trace *0x2117c4} // an address |
| 6473 | @end smallexample |
| 6474 | |
| 6475 | @noindent |
| 6476 | You can abbreviate @code{trace} as @code{tr}. |
| 6477 | |
| 6478 | @vindex $tpnum |
| 6479 | @cindex last tracepoint number |
| 6480 | @cindex recent tracepoint number |
| 6481 | @cindex tracepoint number |
| 6482 | The convenience variable @code{$tpnum} records the tracepoint number |
| 6483 | of the most recently set tracepoint. |
| 6484 | |
| 6485 | @kindex delete tracepoint |
| 6486 | @cindex tracepoint deletion |
| 6487 | @item delete tracepoint @r{[}@var{num}@r{]} |
| 6488 | Permanently delete one or more tracepoints. With no argument, the |
| 6489 | default is to delete all tracepoints. |
| 6490 | |
| 6491 | Examples: |
| 6492 | |
| 6493 | @smallexample |
| 6494 | (@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints |
| 6495 | |
| 6496 | (@value{GDBP}) @b{delete trace} // remove all tracepoints |
| 6497 | @end smallexample |
| 6498 | |
| 6499 | @noindent |
| 6500 | You can abbreviate this command as @code{del tr}. |
| 6501 | @end table |
| 6502 | |
| 6503 | @node Enable and Disable Tracepoints |
| 6504 | @subsection Enable and Disable Tracepoints |
| 6505 | |
| 6506 | @table @code |
| 6507 | @kindex disable tracepoint |
| 6508 | @item disable tracepoint @r{[}@var{num}@r{]} |
| 6509 | Disable tracepoint @var{num}, or all tracepoints if no argument |
| 6510 | @var{num} is given. A disabled tracepoint will have no effect during |
| 6511 | the next trace experiment, but it is not forgotten. You can re-enable |
| 6512 | a disabled tracepoint using the @code{enable tracepoint} command. |
| 6513 | |
| 6514 | @kindex enable tracepoint |
| 6515 | @item enable tracepoint @r{[}@var{num}@r{]} |
| 6516 | Enable tracepoint @var{num}, or all tracepoints. The enabled |
| 6517 | tracepoints will become effective the next time a trace experiment is |
| 6518 | run. |
| 6519 | @end table |
| 6520 | |
| 6521 | @node Tracepoint Passcounts |
| 6522 | @subsection Tracepoint Passcounts |
| 6523 | |
| 6524 | @table @code |
| 6525 | @kindex passcount |
| 6526 | @cindex tracepoint pass count |
| 6527 | @item passcount @r{[}@var{n} @r{[}@var{num}@r{]]} |
| 6528 | Set the @dfn{passcount} of a tracepoint. The passcount is a way to |
| 6529 | automatically stop a trace experiment. If a tracepoint's passcount is |
| 6530 | @var{n}, then the trace experiment will be automatically stopped on |
| 6531 | the @var{n}'th time that tracepoint is hit. If the tracepoint number |
| 6532 | @var{num} is not specified, the @code{passcount} command sets the |
| 6533 | passcount of the most recently defined tracepoint. If no passcount is |
| 6534 | given, the trace experiment will run until stopped explicitly by the |
| 6535 | user. |
| 6536 | |
| 6537 | Examples: |
| 6538 | |
| 6539 | @smallexample |
| 6540 | (@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of |
| 6541 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2} |
| 6542 | |
| 6543 | (@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the |
| 6544 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.} |
| 6545 | (@value{GDBP}) @b{trace foo} |
| 6546 | (@value{GDBP}) @b{pass 3} |
| 6547 | (@value{GDBP}) @b{trace bar} |
| 6548 | (@value{GDBP}) @b{pass 2} |
| 6549 | (@value{GDBP}) @b{trace baz} |
| 6550 | (@value{GDBP}) @b{pass 1} // Stop tracing when foo has been |
| 6551 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has} |
| 6552 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times} |
| 6553 | @exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.} |
| 6554 | @end smallexample |
| 6555 | @end table |
| 6556 | |
| 6557 | @node Tracepoint Actions |
| 6558 | @subsection Tracepoint Action Lists |
| 6559 | |
| 6560 | @table @code |
| 6561 | @kindex actions |
| 6562 | @cindex tracepoint actions |
| 6563 | @item actions @r{[}@var{num}@r{]} |
| 6564 | This command will prompt for a list of actions to be taken when the |
| 6565 | tracepoint is hit. If the tracepoint number @var{num} is not |
| 6566 | specified, this command sets the actions for the one that was most |
| 6567 | recently defined (so that you can define a tracepoint and then say |
| 6568 | @code{actions} without bothering about its number). You specify the |
| 6569 | actions themselves on the following lines, one action at a time, and |
| 6570 | terminate the actions list with a line containing just @code{end}. So |
| 6571 | far, the only defined actions are @code{collect} and |
| 6572 | @code{while-stepping}. |
| 6573 | |
| 6574 | @cindex remove actions from a tracepoint |
| 6575 | To remove all actions from a tracepoint, type @samp{actions @var{num}} |
| 6576 | and follow it immediately with @samp{end}. |
| 6577 | |
| 6578 | @smallexample |
| 6579 | (@value{GDBP}) @b{collect @var{data}} // collect some data |
| 6580 | |
| 6581 | (@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data |
| 6582 | |
| 6583 | (@value{GDBP}) @b{end} // signals the end of actions. |
| 6584 | @end smallexample |
| 6585 | |
| 6586 | In the following example, the action list begins with @code{collect} |
| 6587 | commands indicating the things to be collected when the tracepoint is |
| 6588 | hit. Then, in order to single-step and collect additional data |
| 6589 | following the tracepoint, a @code{while-stepping} command is used, |
| 6590 | followed by the list of things to be collected while stepping. The |
| 6591 | @code{while-stepping} command is terminated by its own separate |
| 6592 | @code{end} command. Lastly, the action list is terminated by an |
| 6593 | @code{end} command. |
| 6594 | |
| 6595 | @smallexample |
| 6596 | (@value{GDBP}) @b{trace foo} |
| 6597 | (@value{GDBP}) @b{actions} |
| 6598 | Enter actions for tracepoint 1, one per line: |
| 6599 | > collect bar,baz |
| 6600 | > collect $regs |
| 6601 | > while-stepping 12 |
| 6602 | > collect $fp, $sp |
| 6603 | > end |
| 6604 | end |
| 6605 | @end smallexample |
| 6606 | |
| 6607 | @kindex collect @r{(tracepoints)} |
| 6608 | @item collect @var{expr1}, @var{expr2}, @dots{} |
| 6609 | Collect values of the given expressions when the tracepoint is hit. |
| 6610 | This command accepts a comma-separated list of any valid expressions. |
| 6611 | In addition to global, static, or local variables, the following |
| 6612 | special arguments are supported: |
| 6613 | |
| 6614 | @table @code |
| 6615 | @item $regs |
| 6616 | collect all registers |
| 6617 | |
| 6618 | @item $args |
| 6619 | collect all function arguments |
| 6620 | |
| 6621 | @item $locals |
| 6622 | collect all local variables. |
| 6623 | @end table |
| 6624 | |
| 6625 | You can give several consecutive @code{collect} commands, each one |
| 6626 | with a single argument, or one @code{collect} command with several |
| 6627 | arguments separated by commas: the effect is the same. |
| 6628 | |
| 6629 | The command @code{info scope} (@pxref{Symbols, info scope}) is |
| 6630 | particularly useful for figuring out what data to collect. |
| 6631 | |
| 6632 | @kindex while-stepping @r{(tracepoints)} |
| 6633 | @item while-stepping @var{n} |
| 6634 | Perform @var{n} single-step traces after the tracepoint, collecting |
| 6635 | new data at each step. The @code{while-stepping} command is |
| 6636 | followed by the list of what to collect while stepping (followed by |
| 6637 | its own @code{end} command): |
| 6638 | |
| 6639 | @smallexample |
| 6640 | > while-stepping 12 |
| 6641 | > collect $regs, myglobal |
| 6642 | > end |
| 6643 | > |
| 6644 | @end smallexample |
| 6645 | |
| 6646 | @noindent |
| 6647 | You may abbreviate @code{while-stepping} as @code{ws} or |
| 6648 | @code{stepping}. |
| 6649 | @end table |
| 6650 | |
| 6651 | @node Listing Tracepoints |
| 6652 | @subsection Listing Tracepoints |
| 6653 | |
| 6654 | @table @code |
| 6655 | @kindex info tracepoints |
| 6656 | @cindex information about tracepoints |
| 6657 | @item info tracepoints @r{[}@var{num}@r{]} |
| 6658 | Display information about the tracepoint @var{num}. If you don't specify |
| 6659 | a tracepoint number, displays information about all the tracepoints |
| 6660 | defined so far. For each tracepoint, the following information is |
| 6661 | shown: |
| 6662 | |
| 6663 | @itemize @bullet |
| 6664 | @item |
| 6665 | its number |
| 6666 | @item |
| 6667 | whether it is enabled or disabled |
| 6668 | @item |
| 6669 | its address |
| 6670 | @item |
| 6671 | its passcount as given by the @code{passcount @var{n}} command |
| 6672 | @item |
| 6673 | its step count as given by the @code{while-stepping @var{n}} command |
| 6674 | @item |
| 6675 | where in the source files is the tracepoint set |
| 6676 | @item |
| 6677 | its action list as given by the @code{actions} command |
| 6678 | @end itemize |
| 6679 | |
| 6680 | @smallexample |
| 6681 | (@value{GDBP}) @b{info trace} |
| 6682 | Num Enb Address PassC StepC What |
| 6683 | 1 y 0x002117c4 0 0 <gdb_asm> |
| 6684 | 2 y 0x0020dc64 0 0 in g_test at g_test.c:1375 |
| 6685 | 3 y 0x0020b1f4 0 0 in get_data at ../foo.c:41 |
| 6686 | (@value{GDBP}) |
| 6687 | @end smallexample |
| 6688 | |
| 6689 | @noindent |
| 6690 | This command can be abbreviated @code{info tp}. |
| 6691 | @end table |
| 6692 | |
| 6693 | @node Starting and Stopping Trace Experiment |
| 6694 | @subsection Starting and Stopping Trace Experiment |
| 6695 | |
| 6696 | @table @code |
| 6697 | @kindex tstart |
| 6698 | @cindex start a new trace experiment |
| 6699 | @cindex collected data discarded |
| 6700 | @item tstart |
| 6701 | This command takes no arguments. It starts the trace experiment, and |
| 6702 | begins collecting data. This has the side effect of discarding all |
| 6703 | the data collected in the trace buffer during the previous trace |
| 6704 | experiment. |
| 6705 | |
| 6706 | @kindex tstop |
| 6707 | @cindex stop a running trace experiment |
| 6708 | @item tstop |
| 6709 | This command takes no arguments. It ends the trace experiment, and |
| 6710 | stops collecting data. |
| 6711 | |
| 6712 | @strong{Note:} a trace experiment and data collection may stop |
| 6713 | automatically if any tracepoint's passcount is reached |
| 6714 | (@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full. |
| 6715 | |
| 6716 | @kindex tstatus |
| 6717 | @cindex status of trace data collection |
| 6718 | @cindex trace experiment, status of |
| 6719 | @item tstatus |
| 6720 | This command displays the status of the current trace data |
| 6721 | collection. |
| 6722 | @end table |
| 6723 | |
| 6724 | Here is an example of the commands we described so far: |
| 6725 | |
| 6726 | @smallexample |
| 6727 | (@value{GDBP}) @b{trace gdb_c_test} |
| 6728 | (@value{GDBP}) @b{actions} |
| 6729 | Enter actions for tracepoint #1, one per line. |
| 6730 | > collect $regs,$locals,$args |
| 6731 | > while-stepping 11 |
| 6732 | > collect $regs |
| 6733 | > end |
| 6734 | > end |
| 6735 | (@value{GDBP}) @b{tstart} |
| 6736 | [time passes @dots{}] |
| 6737 | (@value{GDBP}) @b{tstop} |
| 6738 | @end smallexample |
| 6739 | |
| 6740 | |
| 6741 | @node Analyze Collected Data |
| 6742 | @section Using the collected data |
| 6743 | |
| 6744 | After the tracepoint experiment ends, you use @value{GDBN} commands |
| 6745 | for examining the trace data. The basic idea is that each tracepoint |
| 6746 | collects a trace @dfn{snapshot} every time it is hit and another |
| 6747 | snapshot every time it single-steps. All these snapshots are |
| 6748 | consecutively numbered from zero and go into a buffer, and you can |
| 6749 | examine them later. The way you examine them is to @dfn{focus} on a |
| 6750 | specific trace snapshot. When the remote stub is focused on a trace |
| 6751 | snapshot, it will respond to all @value{GDBN} requests for memory and |
| 6752 | registers by reading from the buffer which belongs to that snapshot, |
| 6753 | rather than from @emph{real} memory or registers of the program being |
| 6754 | debugged. This means that @strong{all} @value{GDBN} commands |
| 6755 | (@code{print}, @code{info registers}, @code{backtrace}, etc.) will |
| 6756 | behave as if we were currently debugging the program state as it was |
| 6757 | when the tracepoint occurred. Any requests for data that are not in |
| 6758 | the buffer will fail. |
| 6759 | |
| 6760 | @menu |
| 6761 | * tfind:: How to select a trace snapshot |
| 6762 | * tdump:: How to display all data for a snapshot |
| 6763 | * save-tracepoints:: How to save tracepoints for a future run |
| 6764 | @end menu |
| 6765 | |
| 6766 | @node tfind |
| 6767 | @subsection @code{tfind @var{n}} |
| 6768 | |
| 6769 | @kindex tfind |
| 6770 | @cindex select trace snapshot |
| 6771 | @cindex find trace snapshot |
| 6772 | The basic command for selecting a trace snapshot from the buffer is |
| 6773 | @code{tfind @var{n}}, which finds trace snapshot number @var{n}, |
| 6774 | counting from zero. If no argument @var{n} is given, the next |
| 6775 | snapshot is selected. |
| 6776 | |
| 6777 | Here are the various forms of using the @code{tfind} command. |
| 6778 | |
| 6779 | @table @code |
| 6780 | @item tfind start |
| 6781 | Find the first snapshot in the buffer. This is a synonym for |
| 6782 | @code{tfind 0} (since 0 is the number of the first snapshot). |
| 6783 | |
| 6784 | @item tfind none |
| 6785 | Stop debugging trace snapshots, resume @emph{live} debugging. |
| 6786 | |
| 6787 | @item tfind end |
| 6788 | Same as @samp{tfind none}. |
| 6789 | |
| 6790 | @item tfind |
| 6791 | No argument means find the next trace snapshot. |
| 6792 | |
| 6793 | @item tfind - |
| 6794 | Find the previous trace snapshot before the current one. This permits |
| 6795 | retracing earlier steps. |
| 6796 | |
| 6797 | @item tfind tracepoint @var{num} |
| 6798 | Find the next snapshot associated with tracepoint @var{num}. Search |
| 6799 | proceeds forward from the last examined trace snapshot. If no |
| 6800 | argument @var{num} is given, it means find the next snapshot collected |
| 6801 | for the same tracepoint as the current snapshot. |
| 6802 | |
| 6803 | @item tfind pc @var{addr} |
| 6804 | Find the next snapshot associated with the value @var{addr} of the |
| 6805 | program counter. Search proceeds forward from the last examined trace |
| 6806 | snapshot. If no argument @var{addr} is given, it means find the next |
| 6807 | snapshot with the same value of PC as the current snapshot. |
| 6808 | |
| 6809 | @item tfind outside @var{addr1}, @var{addr2} |
| 6810 | Find the next snapshot whose PC is outside the given range of |
| 6811 | addresses. |
| 6812 | |
| 6813 | @item tfind range @var{addr1}, @var{addr2} |
| 6814 | Find the next snapshot whose PC is between @var{addr1} and |
| 6815 | @var{addr2}. @c FIXME: Is the range inclusive or exclusive? |
| 6816 | |
| 6817 | @item tfind line @r{[}@var{file}:@r{]}@var{n} |
| 6818 | Find the next snapshot associated with the source line @var{n}. If |
| 6819 | the optional argument @var{file} is given, refer to line @var{n} in |
| 6820 | that source file. Search proceeds forward from the last examined |
| 6821 | trace snapshot. If no argument @var{n} is given, it means find the |
| 6822 | next line other than the one currently being examined; thus saying |
| 6823 | @code{tfind line} repeatedly can appear to have the same effect as |
| 6824 | stepping from line to line in a @emph{live} debugging session. |
| 6825 | @end table |
| 6826 | |
| 6827 | The default arguments for the @code{tfind} commands are specifically |
| 6828 | designed to make it easy to scan through the trace buffer. For |
| 6829 | instance, @code{tfind} with no argument selects the next trace |
| 6830 | snapshot, and @code{tfind -} with no argument selects the previous |
| 6831 | trace snapshot. So, by giving one @code{tfind} command, and then |
| 6832 | simply hitting @key{RET} repeatedly you can examine all the trace |
| 6833 | snapshots in order. Or, by saying @code{tfind -} and then hitting |
| 6834 | @key{RET} repeatedly you can examine the snapshots in reverse order. |
| 6835 | The @code{tfind line} command with no argument selects the snapshot |
| 6836 | for the next source line executed. The @code{tfind pc} command with |
| 6837 | no argument selects the next snapshot with the same program counter |
| 6838 | (PC) as the current frame. The @code{tfind tracepoint} command with |
| 6839 | no argument selects the next trace snapshot collected by the same |
| 6840 | tracepoint as the current one. |
| 6841 | |
| 6842 | In addition to letting you scan through the trace buffer manually, |
| 6843 | these commands make it easy to construct @value{GDBN} scripts that |
| 6844 | scan through the trace buffer and print out whatever collected data |
| 6845 | you are interested in. Thus, if we want to examine the PC, FP, and SP |
| 6846 | registers from each trace frame in the buffer, we can say this: |
| 6847 | |
| 6848 | @smallexample |
| 6849 | (@value{GDBP}) @b{tfind start} |
| 6850 | (@value{GDBP}) @b{while ($trace_frame != -1)} |
| 6851 | > printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \ |
| 6852 | $trace_frame, $pc, $sp, $fp |
| 6853 | > tfind |
| 6854 | > end |
| 6855 | |
| 6856 | Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44 |
| 6857 | Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44 |
| 6858 | Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44 |
| 6859 | Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44 |
| 6860 | Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44 |
| 6861 | Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44 |
| 6862 | Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44 |
| 6863 | Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44 |
| 6864 | Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44 |
| 6865 | Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44 |
| 6866 | Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14 |
| 6867 | @end smallexample |
| 6868 | |
| 6869 | Or, if we want to examine the variable @code{X} at each source line in |
| 6870 | the buffer: |
| 6871 | |
| 6872 | @smallexample |
| 6873 | (@value{GDBP}) @b{tfind start} |
| 6874 | (@value{GDBP}) @b{while ($trace_frame != -1)} |
| 6875 | > printf "Frame %d, X == %d\n", $trace_frame, X |
| 6876 | > tfind line |
| 6877 | > end |
| 6878 | |
| 6879 | Frame 0, X = 1 |
| 6880 | Frame 7, X = 2 |
| 6881 | Frame 13, X = 255 |
| 6882 | @end smallexample |
| 6883 | |
| 6884 | @node tdump |
| 6885 | @subsection @code{tdump} |
| 6886 | @kindex tdump |
| 6887 | @cindex dump all data collected at tracepoint |
| 6888 | @cindex tracepoint data, display |
| 6889 | |
| 6890 | This command takes no arguments. It prints all the data collected at |
| 6891 | the current trace snapshot. |
| 6892 | |
| 6893 | @smallexample |
| 6894 | (@value{GDBP}) @b{trace 444} |
| 6895 | (@value{GDBP}) @b{actions} |
| 6896 | Enter actions for tracepoint #2, one per line: |
| 6897 | > collect $regs, $locals, $args, gdb_long_test |
| 6898 | > end |
| 6899 | |
| 6900 | (@value{GDBP}) @b{tstart} |
| 6901 | |
| 6902 | (@value{GDBP}) @b{tfind line 444} |
| 6903 | #0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66) |
| 6904 | at gdb_test.c:444 |
| 6905 | 444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", ) |
| 6906 | |
| 6907 | (@value{GDBP}) @b{tdump} |
| 6908 | Data collected at tracepoint 2, trace frame 1: |
| 6909 | d0 0xc4aa0085 -995491707 |
| 6910 | d1 0x18 24 |
| 6911 | d2 0x80 128 |
| 6912 | d3 0x33 51 |
| 6913 | d4 0x71aea3d 119204413 |
| 6914 | d5 0x22 34 |
| 6915 | d6 0xe0 224 |
| 6916 | d7 0x380035 3670069 |
| 6917 | a0 0x19e24a 1696330 |
| 6918 | a1 0x3000668 50333288 |
| 6919 | a2 0x100 256 |
| 6920 | a3 0x322000 3284992 |
| 6921 | a4 0x3000698 50333336 |
| 6922 | a5 0x1ad3cc 1758156 |
| 6923 | fp 0x30bf3c 0x30bf3c |
| 6924 | sp 0x30bf34 0x30bf34 |
| 6925 | ps 0x0 0 |
| 6926 | pc 0x20b2c8 0x20b2c8 |
| 6927 | fpcontrol 0x0 0 |
| 6928 | fpstatus 0x0 0 |
| 6929 | fpiaddr 0x0 0 |
| 6930 | p = 0x20e5b4 "gdb-test" |
| 6931 | p1 = (void *) 0x11 |
| 6932 | p2 = (void *) 0x22 |
| 6933 | p3 = (void *) 0x33 |
| 6934 | p4 = (void *) 0x44 |
| 6935 | p5 = (void *) 0x55 |
| 6936 | p6 = (void *) 0x66 |
| 6937 | gdb_long_test = 17 '\021' |
| 6938 | |
| 6939 | (@value{GDBP}) |
| 6940 | @end smallexample |
| 6941 | |
| 6942 | @node save-tracepoints |
| 6943 | @subsection @code{save-tracepoints @var{filename}} |
| 6944 | @kindex save-tracepoints |
| 6945 | @cindex save tracepoints for future sessions |
| 6946 | |
| 6947 | This command saves all current tracepoint definitions together with |
| 6948 | their actions and passcounts, into a file @file{@var{filename}} |
| 6949 | suitable for use in a later debugging session. To read the saved |
| 6950 | tracepoint definitions, use the @code{source} command (@pxref{Command |
| 6951 | Files}). |
| 6952 | |
| 6953 | @node Tracepoint Variables |
| 6954 | @section Convenience Variables for Tracepoints |
| 6955 | @cindex tracepoint variables |
| 6956 | @cindex convenience variables for tracepoints |
| 6957 | |
| 6958 | @table @code |
| 6959 | @vindex $trace_frame |
| 6960 | @item (int) $trace_frame |
| 6961 | The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no |
| 6962 | snapshot is selected. |
| 6963 | |
| 6964 | @vindex $tracepoint |
| 6965 | @item (int) $tracepoint |
| 6966 | The tracepoint for the current trace snapshot. |
| 6967 | |
| 6968 | @vindex $trace_line |
| 6969 | @item (int) $trace_line |
| 6970 | The line number for the current trace snapshot. |
| 6971 | |
| 6972 | @vindex $trace_file |
| 6973 | @item (char []) $trace_file |
| 6974 | The source file for the current trace snapshot. |
| 6975 | |
| 6976 | @vindex $trace_func |
| 6977 | @item (char []) $trace_func |
| 6978 | The name of the function containing @code{$tracepoint}. |
| 6979 | @end table |
| 6980 | |
| 6981 | Note: @code{$trace_file} is not suitable for use in @code{printf}, |
| 6982 | use @code{output} instead. |
| 6983 | |
| 6984 | Here's a simple example of using these convenience variables for |
| 6985 | stepping through all the trace snapshots and printing some of their |
| 6986 | data. |
| 6987 | |
| 6988 | @smallexample |
| 6989 | (@value{GDBP}) @b{tfind start} |
| 6990 | |
| 6991 | (@value{GDBP}) @b{while $trace_frame != -1} |
| 6992 | > output $trace_file |
| 6993 | > printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint |
| 6994 | > tfind |
| 6995 | > end |
| 6996 | @end smallexample |
| 6997 | |
| 6998 | @node Overlays |
| 6999 | @chapter Debugging Programs That Use Overlays |
| 7000 | @cindex overlays |
| 7001 | |
| 7002 | If your program is too large to fit completely in your target system's |
| 7003 | memory, you can sometimes use @dfn{overlays} to work around this |
| 7004 | problem. @value{GDBN} provides some support for debugging programs that |
| 7005 | use overlays. |
| 7006 | |
| 7007 | @menu |
| 7008 | * How Overlays Work:: A general explanation of overlays. |
| 7009 | * Overlay Commands:: Managing overlays in @value{GDBN}. |
| 7010 | * Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are |
| 7011 | mapped by asking the inferior. |
| 7012 | * Overlay Sample Program:: A sample program using overlays. |
| 7013 | @end menu |
| 7014 | |
| 7015 | @node How Overlays Work |
| 7016 | @section How Overlays Work |
| 7017 | @cindex mapped overlays |
| 7018 | @cindex unmapped overlays |
| 7019 | @cindex load address, overlay's |
| 7020 | @cindex mapped address |
| 7021 | @cindex overlay area |
| 7022 | |
| 7023 | Suppose you have a computer whose instruction address space is only 64 |
| 7024 | kilobytes long, but which has much more memory which can be accessed by |
| 7025 | other means: special instructions, segment registers, or memory |
| 7026 | management hardware, for example. Suppose further that you want to |
| 7027 | adapt a program which is larger than 64 kilobytes to run on this system. |
| 7028 | |
| 7029 | One solution is to identify modules of your program which are relatively |
| 7030 | independent, and need not call each other directly; call these modules |
| 7031 | @dfn{overlays}. Separate the overlays from the main program, and place |
| 7032 | their machine code in the larger memory. Place your main program in |
| 7033 | instruction memory, but leave at least enough space there to hold the |
| 7034 | largest overlay as well. |
| 7035 | |
| 7036 | Now, to call a function located in an overlay, you must first copy that |
| 7037 | overlay's machine code from the large memory into the space set aside |
| 7038 | for it in the instruction memory, and then jump to its entry point |
| 7039 | there. |
| 7040 | |
| 7041 | @c NB: In the below the mapped area's size is greater or equal to the |
| 7042 | @c size of all overlays. This is intentional to remind the developer |
| 7043 | @c that overlays don't necessarily need to be the same size. |
| 7044 | |
| 7045 | @smallexample |
| 7046 | @group |
| 7047 | Data Instruction Larger |
| 7048 | Address Space Address Space Address Space |
| 7049 | +-----------+ +-----------+ +-----------+ |
| 7050 | | | | | | | |
| 7051 | +-----------+ +-----------+ +-----------+<-- overlay 1 |
| 7052 | | program | | main | .----| overlay 1 | load address |
| 7053 | | variables | | program | | +-----------+ |
| 7054 | | and heap | | | | | | |
| 7055 | +-----------+ | | | +-----------+<-- overlay 2 |
| 7056 | | | +-----------+ | | | load address |
| 7057 | +-----------+ | | | .-| overlay 2 | |
| 7058 | | | | | | | |
| 7059 | mapped --->+-----------+ | | +-----------+ |
| 7060 | address | | | | | | |
| 7061 | | overlay | <-' | | | |
| 7062 | | area | <---' +-----------+<-- overlay 3 |
| 7063 | | | <---. | | load address |
| 7064 | +-----------+ `--| overlay 3 | |
| 7065 | | | | | |
| 7066 | +-----------+ | | |
| 7067 | +-----------+ |
| 7068 | | | |
| 7069 | +-----------+ |
| 7070 | |
| 7071 | @anchor{A code overlay}A code overlay |
| 7072 | @end group |
| 7073 | @end smallexample |
| 7074 | |
| 7075 | The diagram (@pxref{A code overlay}) shows a system with separate data |
| 7076 | and instruction address spaces. To map an overlay, the program copies |
| 7077 | its code from the larger address space to the instruction address space. |
| 7078 | Since the overlays shown here all use the same mapped address, only one |
| 7079 | may be mapped at a time. For a system with a single address space for |
| 7080 | data and instructions, the diagram would be similar, except that the |
| 7081 | program variables and heap would share an address space with the main |
| 7082 | program and the overlay area. |
| 7083 | |
| 7084 | An overlay loaded into instruction memory and ready for use is called a |
| 7085 | @dfn{mapped} overlay; its @dfn{mapped address} is its address in the |
| 7086 | instruction memory. An overlay not present (or only partially present) |
| 7087 | in instruction memory is called @dfn{unmapped}; its @dfn{load address} |
| 7088 | is its address in the larger memory. The mapped address is also called |
| 7089 | the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also |
| 7090 | called the @dfn{load memory address}, or @dfn{LMA}. |
| 7091 | |
| 7092 | Unfortunately, overlays are not a completely transparent way to adapt a |
| 7093 | program to limited instruction memory. They introduce a new set of |
| 7094 | global constraints you must keep in mind as you design your program: |
| 7095 | |
| 7096 | @itemize @bullet |
| 7097 | |
| 7098 | @item |
| 7099 | Before calling or returning to a function in an overlay, your program |
| 7100 | must make sure that overlay is actually mapped. Otherwise, the call or |
| 7101 | return will transfer control to the right address, but in the wrong |
| 7102 | overlay, and your program will probably crash. |
| 7103 | |
| 7104 | @item |
| 7105 | If the process of mapping an overlay is expensive on your system, you |
| 7106 | will need to choose your overlays carefully to minimize their effect on |
| 7107 | your program's performance. |
| 7108 | |
| 7109 | @item |
| 7110 | The executable file you load onto your system must contain each |
| 7111 | overlay's instructions, appearing at the overlay's load address, not its |
| 7112 | mapped address. However, each overlay's instructions must be relocated |
| 7113 | and its symbols defined as if the overlay were at its mapped address. |
| 7114 | You can use GNU linker scripts to specify different load and relocation |
| 7115 | addresses for pieces of your program; see @ref{Overlay Description,,, |
| 7116 | ld.info, Using ld: the GNU linker}. |
| 7117 | |
| 7118 | @item |
| 7119 | The procedure for loading executable files onto your system must be able |
| 7120 | to load their contents into the larger address space as well as the |
| 7121 | instruction and data spaces. |
| 7122 | |
| 7123 | @end itemize |
| 7124 | |
| 7125 | The overlay system described above is rather simple, and could be |
| 7126 | improved in many ways: |
| 7127 | |
| 7128 | @itemize @bullet |
| 7129 | |
| 7130 | @item |
| 7131 | If your system has suitable bank switch registers or memory management |
| 7132 | hardware, you could use those facilities to make an overlay's load area |
| 7133 | contents simply appear at their mapped address in instruction space. |
| 7134 | This would probably be faster than copying the overlay to its mapped |
| 7135 | area in the usual way. |
| 7136 | |
| 7137 | @item |
| 7138 | If your overlays are small enough, you could set aside more than one |
| 7139 | overlay area, and have more than one overlay mapped at a time. |
| 7140 | |
| 7141 | @item |
| 7142 | You can use overlays to manage data, as well as instructions. In |
| 7143 | general, data overlays are even less transparent to your design than |
| 7144 | code overlays: whereas code overlays only require care when you call or |
| 7145 | return to functions, data overlays require care every time you access |
| 7146 | the data. Also, if you change the contents of a data overlay, you |
| 7147 | must copy its contents back out to its load address before you can copy a |
| 7148 | different data overlay into the same mapped area. |
| 7149 | |
| 7150 | @end itemize |
| 7151 | |
| 7152 | |
| 7153 | @node Overlay Commands |
| 7154 | @section Overlay Commands |
| 7155 | |
| 7156 | To use @value{GDBN}'s overlay support, each overlay in your program must |
| 7157 | correspond to a separate section of the executable file. The section's |
| 7158 | virtual memory address and load memory address must be the overlay's |
| 7159 | mapped and load addresses. Identifying overlays with sections allows |
| 7160 | @value{GDBN} to determine the appropriate address of a function or |
| 7161 | variable, depending on whether the overlay is mapped or not. |
| 7162 | |
| 7163 | @value{GDBN}'s overlay commands all start with the word @code{overlay}; |
| 7164 | you can abbreviate this as @code{ov} or @code{ovly}. The commands are: |
| 7165 | |
| 7166 | @table @code |
| 7167 | @item overlay off |
| 7168 | @kindex overlay off |
| 7169 | Disable @value{GDBN}'s overlay support. When overlay support is |
| 7170 | disabled, @value{GDBN} assumes that all functions and variables are |
| 7171 | always present at their mapped addresses. By default, @value{GDBN}'s |
| 7172 | overlay support is disabled. |
| 7173 | |
| 7174 | @item overlay manual |
| 7175 | @kindex overlay manual |
| 7176 | @cindex manual overlay debugging |
| 7177 | Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN} |
| 7178 | relies on you to tell it which overlays are mapped, and which are not, |
| 7179 | using the @code{overlay map-overlay} and @code{overlay unmap-overlay} |
| 7180 | commands described below. |
| 7181 | |
| 7182 | @item overlay map-overlay @var{overlay} |
| 7183 | @itemx overlay map @var{overlay} |
| 7184 | @kindex overlay map-overlay |
| 7185 | @cindex map an overlay |
| 7186 | Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must |
| 7187 | be the name of the object file section containing the overlay. When an |
| 7188 | overlay is mapped, @value{GDBN} assumes it can find the overlay's |
| 7189 | functions and variables at their mapped addresses. @value{GDBN} assumes |
| 7190 | that any other overlays whose mapped ranges overlap that of |
| 7191 | @var{overlay} are now unmapped. |
| 7192 | |
| 7193 | @item overlay unmap-overlay @var{overlay} |
| 7194 | @itemx overlay unmap @var{overlay} |
| 7195 | @kindex overlay unmap-overlay |
| 7196 | @cindex unmap an overlay |
| 7197 | Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay} |
| 7198 | must be the name of the object file section containing the overlay. |
| 7199 | When an overlay is unmapped, @value{GDBN} assumes it can find the |
| 7200 | overlay's functions and variables at their load addresses. |
| 7201 | |
| 7202 | @item overlay auto |
| 7203 | @kindex overlay auto |
| 7204 | Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN} |
| 7205 | consults a data structure the overlay manager maintains in the inferior |
| 7206 | to see which overlays are mapped. For details, see @ref{Automatic |
| 7207 | Overlay Debugging}. |
| 7208 | |
| 7209 | @item overlay load-target |
| 7210 | @itemx overlay load |
| 7211 | @kindex overlay load-target |
| 7212 | @cindex reloading the overlay table |
| 7213 | Re-read the overlay table from the inferior. Normally, @value{GDBN} |
| 7214 | re-reads the table @value{GDBN} automatically each time the inferior |
| 7215 | stops, so this command should only be necessary if you have changed the |
| 7216 | overlay mapping yourself using @value{GDBN}. This command is only |
| 7217 | useful when using automatic overlay debugging. |
| 7218 | |
| 7219 | @item overlay list-overlays |
| 7220 | @itemx overlay list |
| 7221 | @cindex listing mapped overlays |
| 7222 | Display a list of the overlays currently mapped, along with their mapped |
| 7223 | addresses, load addresses, and sizes. |
| 7224 | |
| 7225 | @end table |
| 7226 | |
| 7227 | Normally, when @value{GDBN} prints a code address, it includes the name |
| 7228 | of the function the address falls in: |
| 7229 | |
| 7230 | @smallexample |
| 7231 | (gdb) print main |
| 7232 | $3 = @{int ()@} 0x11a0 <main> |
| 7233 | @end smallexample |
| 7234 | @noindent |
| 7235 | When overlay debugging is enabled, @value{GDBN} recognizes code in |
| 7236 | unmapped overlays, and prints the names of unmapped functions with |
| 7237 | asterisks around them. For example, if @code{foo} is a function in an |
| 7238 | unmapped overlay, @value{GDBN} prints it this way: |
| 7239 | |
| 7240 | @smallexample |
| 7241 | (gdb) overlay list |
| 7242 | No sections are mapped. |
| 7243 | (gdb) print foo |
| 7244 | $5 = @{int (int)@} 0x100000 <*foo*> |
| 7245 | @end smallexample |
| 7246 | @noindent |
| 7247 | When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's |
| 7248 | name normally: |
| 7249 | |
| 7250 | @smallexample |
| 7251 | (gdb) overlay list |
| 7252 | Section .ov.foo.text, loaded at 0x100000 - 0x100034, |
| 7253 | mapped at 0x1016 - 0x104a |
| 7254 | (gdb) print foo |
| 7255 | $6 = @{int (int)@} 0x1016 <foo> |
| 7256 | @end smallexample |
| 7257 | |
| 7258 | When overlay debugging is enabled, @value{GDBN} can find the correct |
| 7259 | address for functions and variables in an overlay, whether or not the |
| 7260 | overlay is mapped. This allows most @value{GDBN} commands, like |
| 7261 | @code{break} and @code{disassemble}, to work normally, even on unmapped |
| 7262 | code. However, @value{GDBN}'s breakpoint support has some limitations: |
| 7263 | |
| 7264 | @itemize @bullet |
| 7265 | @item |
| 7266 | @cindex breakpoints in overlays |
| 7267 | @cindex overlays, setting breakpoints in |
| 7268 | You can set breakpoints in functions in unmapped overlays, as long as |
| 7269 | @value{GDBN} can write to the overlay at its load address. |
| 7270 | @item |
| 7271 | @value{GDBN} can not set hardware or simulator-based breakpoints in |
| 7272 | unmapped overlays. However, if you set a breakpoint at the end of your |
| 7273 | overlay manager (and tell @value{GDBN} which overlays are now mapped, if |
| 7274 | you are using manual overlay management), @value{GDBN} will re-set its |
| 7275 | breakpoints properly. |
| 7276 | @end itemize |
| 7277 | |
| 7278 | |
| 7279 | @node Automatic Overlay Debugging |
| 7280 | @section Automatic Overlay Debugging |
| 7281 | @cindex automatic overlay debugging |
| 7282 | |
| 7283 | @value{GDBN} can automatically track which overlays are mapped and which |
| 7284 | are not, given some simple co-operation from the overlay manager in the |
| 7285 | inferior. If you enable automatic overlay debugging with the |
| 7286 | @code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN} |
| 7287 | looks in the inferior's memory for certain variables describing the |
| 7288 | current state of the overlays. |
| 7289 | |
| 7290 | Here are the variables your overlay manager must define to support |
| 7291 | @value{GDBN}'s automatic overlay debugging: |
| 7292 | |
| 7293 | @table @asis |
| 7294 | |
| 7295 | @item @code{_ovly_table}: |
| 7296 | This variable must be an array of the following structures: |
| 7297 | |
| 7298 | @smallexample |
| 7299 | struct |
| 7300 | @{ |
| 7301 | /* The overlay's mapped address. */ |
| 7302 | unsigned long vma; |
| 7303 | |
| 7304 | /* The size of the overlay, in bytes. */ |
| 7305 | unsigned long size; |
| 7306 | |
| 7307 | /* The overlay's load address. */ |
| 7308 | unsigned long lma; |
| 7309 | |
| 7310 | /* Non-zero if the overlay is currently mapped; |
| 7311 | zero otherwise. */ |
| 7312 | unsigned long mapped; |
| 7313 | @} |
| 7314 | @end smallexample |
| 7315 | |
| 7316 | @item @code{_novlys}: |
| 7317 | This variable must be a four-byte signed integer, holding the total |
| 7318 | number of elements in @code{_ovly_table}. |
| 7319 | |
| 7320 | @end table |
| 7321 | |
| 7322 | To decide whether a particular overlay is mapped or not, @value{GDBN} |
| 7323 | looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and |
| 7324 | @code{lma} members equal the VMA and LMA of the overlay's section in the |
| 7325 | executable file. When @value{GDBN} finds a matching entry, it consults |
| 7326 | the entry's @code{mapped} member to determine whether the overlay is |
| 7327 | currently mapped. |
| 7328 | |
| 7329 | In addition, your overlay manager may define a function called |
| 7330 | @code{_ovly_debug_event}. If this function is defined, @value{GDBN} |
| 7331 | will silently set a breakpoint there. If the overlay manager then |
| 7332 | calls this function whenever it has changed the overlay table, this |
| 7333 | will enable @value{GDBN} to accurately keep track of which overlays |
| 7334 | are in program memory, and update any breakpoints that may be set |
| 7335 | in overlays. This will allow breakpoints to work even if the |
| 7336 | overlays are kept in ROM or other non-writable memory while they |
| 7337 | are not being executed. |
| 7338 | |
| 7339 | @node Overlay Sample Program |
| 7340 | @section Overlay Sample Program |
| 7341 | @cindex overlay example program |
| 7342 | |
| 7343 | When linking a program which uses overlays, you must place the overlays |
| 7344 | at their load addresses, while relocating them to run at their mapped |
| 7345 | addresses. To do this, you must write a linker script (@pxref{Overlay |
| 7346 | Description,,, ld.info, Using ld: the GNU linker}). Unfortunately, |
| 7347 | since linker scripts are specific to a particular host system, target |
| 7348 | architecture, and target memory layout, this manual cannot provide |
| 7349 | portable sample code demonstrating @value{GDBN}'s overlay support. |
| 7350 | |
| 7351 | However, the @value{GDBN} source distribution does contain an overlaid |
| 7352 | program, with linker scripts for a few systems, as part of its test |
| 7353 | suite. The program consists of the following files from |
| 7354 | @file{gdb/testsuite/gdb.base}: |
| 7355 | |
| 7356 | @table @file |
| 7357 | @item overlays.c |
| 7358 | The main program file. |
| 7359 | @item ovlymgr.c |
| 7360 | A simple overlay manager, used by @file{overlays.c}. |
| 7361 | @item foo.c |
| 7362 | @itemx bar.c |
| 7363 | @itemx baz.c |
| 7364 | @itemx grbx.c |
| 7365 | Overlay modules, loaded and used by @file{overlays.c}. |
| 7366 | @item d10v.ld |
| 7367 | @itemx m32r.ld |
| 7368 | Linker scripts for linking the test program on the @code{d10v-elf} |
| 7369 | and @code{m32r-elf} targets. |
| 7370 | @end table |
| 7371 | |
| 7372 | You can build the test program using the @code{d10v-elf} GCC |
| 7373 | cross-compiler like this: |
| 7374 | |
| 7375 | @smallexample |
| 7376 | $ d10v-elf-gcc -g -c overlays.c |
| 7377 | $ d10v-elf-gcc -g -c ovlymgr.c |
| 7378 | $ d10v-elf-gcc -g -c foo.c |
| 7379 | $ d10v-elf-gcc -g -c bar.c |
| 7380 | $ d10v-elf-gcc -g -c baz.c |
| 7381 | $ d10v-elf-gcc -g -c grbx.c |
| 7382 | $ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \ |
| 7383 | baz.o grbx.o -Wl,-Td10v.ld -o overlays |
| 7384 | @end smallexample |
| 7385 | |
| 7386 | The build process is identical for any other architecture, except that |
| 7387 | you must substitute the appropriate compiler and linker script for the |
| 7388 | target system for @code{d10v-elf-gcc} and @code{d10v.ld}. |
| 7389 | |
| 7390 | |
| 7391 | @node Languages |
| 7392 | @chapter Using @value{GDBN} with Different Languages |
| 7393 | @cindex languages |
| 7394 | |
| 7395 | Although programming languages generally have common aspects, they are |
| 7396 | rarely expressed in the same manner. For instance, in ANSI C, |
| 7397 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in |
| 7398 | Modula-2, it is accomplished by @code{p^}. Values can also be |
| 7399 | represented (and displayed) differently. Hex numbers in C appear as |
| 7400 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. |
| 7401 | |
| 7402 | @cindex working language |
| 7403 | Language-specific information is built into @value{GDBN} for some languages, |
| 7404 | allowing you to express operations like the above in your program's |
| 7405 | native language, and allowing @value{GDBN} to output values in a manner |
| 7406 | consistent with the syntax of your program's native language. The |
| 7407 | language you use to build expressions is called the @dfn{working |
| 7408 | language}. |
| 7409 | |
| 7410 | @menu |
| 7411 | * Setting:: Switching between source languages |
| 7412 | * Show:: Displaying the language |
| 7413 | * Checks:: Type and range checks |
| 7414 | * Support:: Supported languages |
| 7415 | @end menu |
| 7416 | |
| 7417 | @node Setting |
| 7418 | @section Switching between source languages |
| 7419 | |
| 7420 | There are two ways to control the working language---either have @value{GDBN} |
| 7421 | set it automatically, or select it manually yourself. You can use the |
| 7422 | @code{set language} command for either purpose. On startup, @value{GDBN} |
| 7423 | defaults to setting the language automatically. The working language is |
| 7424 | used to determine how expressions you type are interpreted, how values |
| 7425 | are printed, etc. |
| 7426 | |
| 7427 | In addition to the working language, every source file that |
| 7428 | @value{GDBN} knows about has its own working language. For some object |
| 7429 | file formats, the compiler might indicate which language a particular |
| 7430 | source file is in. However, most of the time @value{GDBN} infers the |
| 7431 | language from the name of the file. The language of a source file |
| 7432 | controls whether C@t{++} names are demangled---this way @code{backtrace} can |
| 7433 | show each frame appropriately for its own language. There is no way to |
| 7434 | set the language of a source file from within @value{GDBN}, but you can |
| 7435 | set the language associated with a filename extension. @xref{Show, , |
| 7436 | Displaying the language}. |
| 7437 | |
| 7438 | This is most commonly a problem when you use a program, such |
| 7439 | as @code{cfront} or @code{f2c}, that generates C but is written in |
| 7440 | another language. In that case, make the |
| 7441 | program use @code{#line} directives in its C output; that way |
| 7442 | @value{GDBN} will know the correct language of the source code of the original |
| 7443 | program, and will display that source code, not the generated C code. |
| 7444 | |
| 7445 | @menu |
| 7446 | * Filenames:: Filename extensions and languages. |
| 7447 | * Manually:: Setting the working language manually |
| 7448 | * Automatically:: Having @value{GDBN} infer the source language |
| 7449 | @end menu |
| 7450 | |
| 7451 | @node Filenames |
| 7452 | @subsection List of filename extensions and languages |
| 7453 | |
| 7454 | If a source file name ends in one of the following extensions, then |
| 7455 | @value{GDBN} infers that its language is the one indicated. |
| 7456 | |
| 7457 | @table @file |
| 7458 | |
| 7459 | @item .c |
| 7460 | C source file |
| 7461 | |
| 7462 | @item .C |
| 7463 | @itemx .cc |
| 7464 | @itemx .cp |
| 7465 | @itemx .cpp |
| 7466 | @itemx .cxx |
| 7467 | @itemx .c++ |
| 7468 | C@t{++} source file |
| 7469 | |
| 7470 | @item .f |
| 7471 | @itemx .F |
| 7472 | Fortran source file |
| 7473 | |
| 7474 | @item .mod |
| 7475 | Modula-2 source file |
| 7476 | |
| 7477 | @item .s |
| 7478 | @itemx .S |
| 7479 | Assembler source file. This actually behaves almost like C, but |
| 7480 | @value{GDBN} does not skip over function prologues when stepping. |
| 7481 | @end table |
| 7482 | |
| 7483 | In addition, you may set the language associated with a filename |
| 7484 | extension. @xref{Show, , Displaying the language}. |
| 7485 | |
| 7486 | @node Manually |
| 7487 | @subsection Setting the working language |
| 7488 | |
| 7489 | If you allow @value{GDBN} to set the language automatically, |
| 7490 | expressions are interpreted the same way in your debugging session and |
| 7491 | your program. |
| 7492 | |
| 7493 | @kindex set language |
| 7494 | If you wish, you may set the language manually. To do this, issue the |
| 7495 | command @samp{set language @var{lang}}, where @var{lang} is the name of |
| 7496 | a language, such as |
| 7497 | @code{c} or @code{modula-2}. |
| 7498 | For a list of the supported languages, type @samp{set language}. |
| 7499 | |
| 7500 | Setting the language manually prevents @value{GDBN} from updating the working |
| 7501 | language automatically. This can lead to confusion if you try |
| 7502 | to debug a program when the working language is not the same as the |
| 7503 | source language, when an expression is acceptable to both |
| 7504 | languages---but means different things. For instance, if the current |
| 7505 | source file were written in C, and @value{GDBN} was parsing Modula-2, a |
| 7506 | command such as: |
| 7507 | |
| 7508 | @smallexample |
| 7509 | print a = b + c |
| 7510 | @end smallexample |
| 7511 | |
| 7512 | @noindent |
| 7513 | might not have the effect you intended. In C, this means to add |
| 7514 | @code{b} and @code{c} and place the result in @code{a}. The result |
| 7515 | printed would be the value of @code{a}. In Modula-2, this means to compare |
| 7516 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. |
| 7517 | |
| 7518 | @node Automatically |
| 7519 | @subsection Having @value{GDBN} infer the source language |
| 7520 | |
| 7521 | To have @value{GDBN} set the working language automatically, use |
| 7522 | @samp{set language local} or @samp{set language auto}. @value{GDBN} |
| 7523 | then infers the working language. That is, when your program stops in a |
| 7524 | frame (usually by encountering a breakpoint), @value{GDBN} sets the |
| 7525 | working language to the language recorded for the function in that |
| 7526 | frame. If the language for a frame is unknown (that is, if the function |
| 7527 | or block corresponding to the frame was defined in a source file that |
| 7528 | does not have a recognized extension), the current working language is |
| 7529 | not changed, and @value{GDBN} issues a warning. |
| 7530 | |
| 7531 | This may not seem necessary for most programs, which are written |
| 7532 | entirely in one source language. However, program modules and libraries |
| 7533 | written in one source language can be used by a main program written in |
| 7534 | a different source language. Using @samp{set language auto} in this |
| 7535 | case frees you from having to set the working language manually. |
| 7536 | |
| 7537 | @node Show |
| 7538 | @section Displaying the language |
| 7539 | |
| 7540 | The following commands help you find out which language is the |
| 7541 | working language, and also what language source files were written in. |
| 7542 | |
| 7543 | @kindex show language |
| 7544 | @kindex info frame@r{, show the source language} |
| 7545 | @kindex info source@r{, show the source language} |
| 7546 | @table @code |
| 7547 | @item show language |
| 7548 | Display the current working language. This is the |
| 7549 | language you can use with commands such as @code{print} to |
| 7550 | build and compute expressions that may involve variables in your program. |
| 7551 | |
| 7552 | @item info frame |
| 7553 | Display the source language for this frame. This language becomes the |
| 7554 | working language if you use an identifier from this frame. |
| 7555 | @xref{Frame Info, ,Information about a frame}, to identify the other |
| 7556 | information listed here. |
| 7557 | |
| 7558 | @item info source |
| 7559 | Display the source language of this source file. |
| 7560 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other |
| 7561 | information listed here. |
| 7562 | @end table |
| 7563 | |
| 7564 | In unusual circumstances, you may have source files with extensions |
| 7565 | not in the standard list. You can then set the extension associated |
| 7566 | with a language explicitly: |
| 7567 | |
| 7568 | @kindex set extension-language |
| 7569 | @kindex info extensions |
| 7570 | @table @code |
| 7571 | @item set extension-language @var{.ext} @var{language} |
| 7572 | Set source files with extension @var{.ext} to be assumed to be in |
| 7573 | the source language @var{language}. |
| 7574 | |
| 7575 | @item info extensions |
| 7576 | List all the filename extensions and the associated languages. |
| 7577 | @end table |
| 7578 | |
| 7579 | @node Checks |
| 7580 | @section Type and range checking |
| 7581 | |
| 7582 | @quotation |
| 7583 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range |
| 7584 | checking are included, but they do not yet have any effect. This |
| 7585 | section documents the intended facilities. |
| 7586 | @end quotation |
| 7587 | @c FIXME remove warning when type/range code added |
| 7588 | |
| 7589 | Some languages are designed to guard you against making seemingly common |
| 7590 | errors through a series of compile- and run-time checks. These include |
| 7591 | checking the type of arguments to functions and operators, and making |
| 7592 | sure mathematical overflows are caught at run time. Checks such as |
| 7593 | these help to ensure a program's correctness once it has been compiled |
| 7594 | by eliminating type mismatches, and providing active checks for range |
| 7595 | errors when your program is running. |
| 7596 | |
| 7597 | @value{GDBN} can check for conditions like the above if you wish. |
| 7598 | Although @value{GDBN} does not check the statements in your program, it |
| 7599 | can check expressions entered directly into @value{GDBN} for evaluation via |
| 7600 | the @code{print} command, for example. As with the working language, |
| 7601 | @value{GDBN} can also decide whether or not to check automatically based on |
| 7602 | your program's source language. @xref{Support, ,Supported languages}, |
| 7603 | for the default settings of supported languages. |
| 7604 | |
| 7605 | @menu |
| 7606 | * Type Checking:: An overview of type checking |
| 7607 | * Range Checking:: An overview of range checking |
| 7608 | @end menu |
| 7609 | |
| 7610 | @cindex type checking |
| 7611 | @cindex checks, type |
| 7612 | @node Type Checking |
| 7613 | @subsection An overview of type checking |
| 7614 | |
| 7615 | Some languages, such as Modula-2, are strongly typed, meaning that the |
| 7616 | arguments to operators and functions have to be of the correct type, |
| 7617 | otherwise an error occurs. These checks prevent type mismatch |
| 7618 | errors from ever causing any run-time problems. For example, |
| 7619 | |
| 7620 | @smallexample |
| 7621 | 1 + 2 @result{} 3 |
| 7622 | @exdent but |
| 7623 | @error{} 1 + 2.3 |
| 7624 | @end smallexample |
| 7625 | |
| 7626 | The second example fails because the @code{CARDINAL} 1 is not |
| 7627 | type-compatible with the @code{REAL} 2.3. |
| 7628 | |
| 7629 | For the expressions you use in @value{GDBN} commands, you can tell the |
| 7630 | @value{GDBN} type checker to skip checking; |
| 7631 | to treat any mismatches as errors and abandon the expression; |
| 7632 | or to only issue warnings when type mismatches occur, |
| 7633 | but evaluate the expression anyway. When you choose the last of |
| 7634 | these, @value{GDBN} evaluates expressions like the second example above, but |
| 7635 | also issues a warning. |
| 7636 | |
| 7637 | Even if you turn type checking off, there may be other reasons |
| 7638 | related to type that prevent @value{GDBN} from evaluating an expression. |
| 7639 | For instance, @value{GDBN} does not know how to add an @code{int} and |
| 7640 | a @code{struct foo}. These particular type errors have nothing to do |
| 7641 | with the language in use, and usually arise from expressions, such as |
| 7642 | the one described above, which make little sense to evaluate anyway. |
| 7643 | |
| 7644 | Each language defines to what degree it is strict about type. For |
| 7645 | instance, both Modula-2 and C require the arguments to arithmetical |
| 7646 | operators to be numbers. In C, enumerated types and pointers can be |
| 7647 | represented as numbers, so that they are valid arguments to mathematical |
| 7648 | operators. @xref{Support, ,Supported languages}, for further |
| 7649 | details on specific languages. |
| 7650 | |
| 7651 | @value{GDBN} provides some additional commands for controlling the type checker: |
| 7652 | |
| 7653 | @kindex set check@r{, type} |
| 7654 | @kindex set check type |
| 7655 | @kindex show check type |
| 7656 | @table @code |
| 7657 | @item set check type auto |
| 7658 | Set type checking on or off based on the current working language. |
| 7659 | @xref{Support, ,Supported languages}, for the default settings for |
| 7660 | each language. |
| 7661 | |
| 7662 | @item set check type on |
| 7663 | @itemx set check type off |
| 7664 | Set type checking on or off, overriding the default setting for the |
| 7665 | current working language. Issue a warning if the setting does not |
| 7666 | match the language default. If any type mismatches occur in |
| 7667 | evaluating an expression while type checking is on, @value{GDBN} prints a |
| 7668 | message and aborts evaluation of the expression. |
| 7669 | |
| 7670 | @item set check type warn |
| 7671 | Cause the type checker to issue warnings, but to always attempt to |
| 7672 | evaluate the expression. Evaluating the expression may still |
| 7673 | be impossible for other reasons. For example, @value{GDBN} cannot add |
| 7674 | numbers and structures. |
| 7675 | |
| 7676 | @item show type |
| 7677 | Show the current setting of the type checker, and whether or not @value{GDBN} |
| 7678 | is setting it automatically. |
| 7679 | @end table |
| 7680 | |
| 7681 | @cindex range checking |
| 7682 | @cindex checks, range |
| 7683 | @node Range Checking |
| 7684 | @subsection An overview of range checking |
| 7685 | |
| 7686 | In some languages (such as Modula-2), it is an error to exceed the |
| 7687 | bounds of a type; this is enforced with run-time checks. Such range |
| 7688 | checking is meant to ensure program correctness by making sure |
| 7689 | computations do not overflow, or indices on an array element access do |
| 7690 | not exceed the bounds of the array. |
| 7691 | |
| 7692 | For expressions you use in @value{GDBN} commands, you can tell |
| 7693 | @value{GDBN} to treat range errors in one of three ways: ignore them, |
| 7694 | always treat them as errors and abandon the expression, or issue |
| 7695 | warnings but evaluate the expression anyway. |
| 7696 | |
| 7697 | A range error can result from numerical overflow, from exceeding an |
| 7698 | array index bound, or when you type a constant that is not a member |
| 7699 | of any type. Some languages, however, do not treat overflows as an |
| 7700 | error. In many implementations of C, mathematical overflow causes the |
| 7701 | result to ``wrap around'' to lower values---for example, if @var{m} is |
| 7702 | the largest integer value, and @var{s} is the smallest, then |
| 7703 | |
| 7704 | @smallexample |
| 7705 | @var{m} + 1 @result{} @var{s} |
| 7706 | @end smallexample |
| 7707 | |
| 7708 | This, too, is specific to individual languages, and in some cases |
| 7709 | specific to individual compilers or machines. @xref{Support, , |
| 7710 | Supported languages}, for further details on specific languages. |
| 7711 | |
| 7712 | @value{GDBN} provides some additional commands for controlling the range checker: |
| 7713 | |
| 7714 | @kindex set check@r{, range} |
| 7715 | @kindex set check range |
| 7716 | @kindex show check range |
| 7717 | @table @code |
| 7718 | @item set check range auto |
| 7719 | Set range checking on or off based on the current working language. |
| 7720 | @xref{Support, ,Supported languages}, for the default settings for |
| 7721 | each language. |
| 7722 | |
| 7723 | @item set check range on |
| 7724 | @itemx set check range off |
| 7725 | Set range checking on or off, overriding the default setting for the |
| 7726 | current working language. A warning is issued if the setting does not |
| 7727 | match the language default. If a range error occurs and range checking is on, |
| 7728 | then a message is printed and evaluation of the expression is aborted. |
| 7729 | |
| 7730 | @item set check range warn |
| 7731 | Output messages when the @value{GDBN} range checker detects a range error, |
| 7732 | but attempt to evaluate the expression anyway. Evaluating the |
| 7733 | expression may still be impossible for other reasons, such as accessing |
| 7734 | memory that the process does not own (a typical example from many Unix |
| 7735 | systems). |
| 7736 | |
| 7737 | @item show range |
| 7738 | Show the current setting of the range checker, and whether or not it is |
| 7739 | being set automatically by @value{GDBN}. |
| 7740 | @end table |
| 7741 | |
| 7742 | @node Support |
| 7743 | @section Supported languages |
| 7744 | |
| 7745 | @value{GDBN} supports C, C@t{++}, Fortran, Java, assembly, and Modula-2. |
| 7746 | @c This is false ... |
| 7747 | Some @value{GDBN} features may be used in expressions regardless of the |
| 7748 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, |
| 7749 | and the @samp{@{type@}addr} construct (@pxref{Expressions, |
| 7750 | ,Expressions}) can be used with the constructs of any supported |
| 7751 | language. |
| 7752 | |
| 7753 | The following sections detail to what degree each source language is |
| 7754 | supported by @value{GDBN}. These sections are not meant to be language |
| 7755 | tutorials or references, but serve only as a reference guide to what the |
| 7756 | @value{GDBN} expression parser accepts, and what input and output |
| 7757 | formats should look like for different languages. There are many good |
| 7758 | books written on each of these languages; please look to these for a |
| 7759 | language reference or tutorial. |
| 7760 | |
| 7761 | @menu |
| 7762 | * C:: C and C@t{++} |
| 7763 | * Modula-2:: Modula-2 |
| 7764 | @end menu |
| 7765 | |
| 7766 | @node C |
| 7767 | @subsection C and C@t{++} |
| 7768 | |
| 7769 | @cindex C and C@t{++} |
| 7770 | @cindex expressions in C or C@t{++} |
| 7771 | |
| 7772 | Since C and C@t{++} are so closely related, many features of @value{GDBN} apply |
| 7773 | to both languages. Whenever this is the case, we discuss those languages |
| 7774 | together. |
| 7775 | |
| 7776 | @cindex C@t{++} |
| 7777 | @cindex @code{g++}, @sc{gnu} C@t{++} compiler |
| 7778 | @cindex @sc{gnu} C@t{++} |
| 7779 | The C@t{++} debugging facilities are jointly implemented by the C@t{++} |
| 7780 | compiler and @value{GDBN}. Therefore, to debug your C@t{++} code |
| 7781 | effectively, you must compile your C@t{++} programs with a supported |
| 7782 | C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++} |
| 7783 | compiler (@code{aCC}). |
| 7784 | |
| 7785 | For best results when using @sc{gnu} C@t{++}, use the stabs debugging |
| 7786 | format. You can select that format explicitly with the @code{g++} |
| 7787 | command-line options @samp{-gstabs} or @samp{-gstabs+}. See |
| 7788 | @ref{Debugging Options,,Options for Debugging Your Program or @sc{gnu} |
| 7789 | CC, gcc.info, Using @sc{gnu} CC}, for more information. |
| 7790 | |
| 7791 | @menu |
| 7792 | * C Operators:: C and C@t{++} operators |
| 7793 | * C Constants:: C and C@t{++} constants |
| 7794 | * C plus plus expressions:: C@t{++} expressions |
| 7795 | * C Defaults:: Default settings for C and C@t{++} |
| 7796 | * C Checks:: C and C@t{++} type and range checks |
| 7797 | * Debugging C:: @value{GDBN} and C |
| 7798 | * Debugging C plus plus:: @value{GDBN} features for C@t{++} |
| 7799 | @end menu |
| 7800 | |
| 7801 | @node C Operators |
| 7802 | @subsubsection C and C@t{++} operators |
| 7803 | |
| 7804 | @cindex C and C@t{++} operators |
| 7805 | |
| 7806 | Operators must be defined on values of specific types. For instance, |
| 7807 | @code{+} is defined on numbers, but not on structures. Operators are |
| 7808 | often defined on groups of types. |
| 7809 | |
| 7810 | For the purposes of C and C@t{++}, the following definitions hold: |
| 7811 | |
| 7812 | @itemize @bullet |
| 7813 | |
| 7814 | @item |
| 7815 | @emph{Integral types} include @code{int} with any of its storage-class |
| 7816 | specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}. |
| 7817 | |
| 7818 | @item |
| 7819 | @emph{Floating-point types} include @code{float}, @code{double}, and |
| 7820 | @code{long double} (if supported by the target platform). |
| 7821 | |
| 7822 | @item |
| 7823 | @emph{Pointer types} include all types defined as @code{(@var{type} *)}. |
| 7824 | |
| 7825 | @item |
| 7826 | @emph{Scalar types} include all of the above. |
| 7827 | |
| 7828 | @end itemize |
| 7829 | |
| 7830 | @noindent |
| 7831 | The following operators are supported. They are listed here |
| 7832 | in order of increasing precedence: |
| 7833 | |
| 7834 | @table @code |
| 7835 | @item , |
| 7836 | The comma or sequencing operator. Expressions in a comma-separated list |
| 7837 | are evaluated from left to right, with the result of the entire |
| 7838 | expression being the last expression evaluated. |
| 7839 | |
| 7840 | @item = |
| 7841 | Assignment. The value of an assignment expression is the value |
| 7842 | assigned. Defined on scalar types. |
| 7843 | |
| 7844 | @item @var{op}= |
| 7845 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, |
| 7846 | and translated to @w{@code{@var{a} = @var{a op b}}}. |
| 7847 | @w{@code{@var{op}=}} and @code{=} have the same precedence. |
| 7848 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, |
| 7849 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. |
| 7850 | |
| 7851 | @item ?: |
| 7852 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought |
| 7853 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an |
| 7854 | integral type. |
| 7855 | |
| 7856 | @item || |
| 7857 | Logical @sc{or}. Defined on integral types. |
| 7858 | |
| 7859 | @item && |
| 7860 | Logical @sc{and}. Defined on integral types. |
| 7861 | |
| 7862 | @item | |
| 7863 | Bitwise @sc{or}. Defined on integral types. |
| 7864 | |
| 7865 | @item ^ |
| 7866 | Bitwise exclusive-@sc{or}. Defined on integral types. |
| 7867 | |
| 7868 | @item & |
| 7869 | Bitwise @sc{and}. Defined on integral types. |
| 7870 | |
| 7871 | @item ==@r{, }!= |
| 7872 | Equality and inequality. Defined on scalar types. The value of these |
| 7873 | expressions is 0 for false and non-zero for true. |
| 7874 | |
| 7875 | @item <@r{, }>@r{, }<=@r{, }>= |
| 7876 | Less than, greater than, less than or equal, greater than or equal. |
| 7877 | Defined on scalar types. The value of these expressions is 0 for false |
| 7878 | and non-zero for true. |
| 7879 | |
| 7880 | @item <<@r{, }>> |
| 7881 | left shift, and right shift. Defined on integral types. |
| 7882 | |
| 7883 | @item @@ |
| 7884 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
| 7885 | |
| 7886 | @item +@r{, }- |
| 7887 | Addition and subtraction. Defined on integral types, floating-point types and |
| 7888 | pointer types. |
| 7889 | |
| 7890 | @item *@r{, }/@r{, }% |
| 7891 | Multiplication, division, and modulus. Multiplication and division are |
| 7892 | defined on integral and floating-point types. Modulus is defined on |
| 7893 | integral types. |
| 7894 | |
| 7895 | @item ++@r{, }-- |
| 7896 | Increment and decrement. When appearing before a variable, the |
| 7897 | operation is performed before the variable is used in an expression; |
| 7898 | when appearing after it, the variable's value is used before the |
| 7899 | operation takes place. |
| 7900 | |
| 7901 | @item * |
| 7902 | Pointer dereferencing. Defined on pointer types. Same precedence as |
| 7903 | @code{++}. |
| 7904 | |
| 7905 | @item & |
| 7906 | Address operator. Defined on variables. Same precedence as @code{++}. |
| 7907 | |
| 7908 | For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is |
| 7909 | allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})} |
| 7910 | (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address |
| 7911 | where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is |
| 7912 | stored. |
| 7913 | |
| 7914 | @item - |
| 7915 | Negative. Defined on integral and floating-point types. Same |
| 7916 | precedence as @code{++}. |
| 7917 | |
| 7918 | @item ! |
| 7919 | Logical negation. Defined on integral types. Same precedence as |
| 7920 | @code{++}. |
| 7921 | |
| 7922 | @item ~ |
| 7923 | Bitwise complement operator. Defined on integral types. Same precedence as |
| 7924 | @code{++}. |
| 7925 | |
| 7926 | |
| 7927 | @item .@r{, }-> |
| 7928 | Structure member, and pointer-to-structure member. For convenience, |
| 7929 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a |
| 7930 | pointer based on the stored type information. |
| 7931 | Defined on @code{struct} and @code{union} data. |
| 7932 | |
| 7933 | @item .*@r{, }->* |
| 7934 | Dereferences of pointers to members. |
| 7935 | |
| 7936 | @item [] |
| 7937 | Array indexing. @code{@var{a}[@var{i}]} is defined as |
| 7938 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. |
| 7939 | |
| 7940 | @item () |
| 7941 | Function parameter list. Same precedence as @code{->}. |
| 7942 | |
| 7943 | @item :: |
| 7944 | C@t{++} scope resolution operator. Defined on @code{struct}, @code{union}, |
| 7945 | and @code{class} types. |
| 7946 | |
| 7947 | @item :: |
| 7948 | Doubled colons also represent the @value{GDBN} scope operator |
| 7949 | (@pxref{Expressions, ,Expressions}). Same precedence as @code{::}, |
| 7950 | above. |
| 7951 | @end table |
| 7952 | |
| 7953 | If an operator is redefined in the user code, @value{GDBN} usually |
| 7954 | attempts to invoke the redefined version instead of using the operator's |
| 7955 | predefined meaning. |
| 7956 | |
| 7957 | @menu |
| 7958 | * C Constants:: |
| 7959 | @end menu |
| 7960 | |
| 7961 | @node C Constants |
| 7962 | @subsubsection C and C@t{++} constants |
| 7963 | |
| 7964 | @cindex C and C@t{++} constants |
| 7965 | |
| 7966 | @value{GDBN} allows you to express the constants of C and C@t{++} in the |
| 7967 | following ways: |
| 7968 | |
| 7969 | @itemize @bullet |
| 7970 | @item |
| 7971 | Integer constants are a sequence of digits. Octal constants are |
| 7972 | specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants |
| 7973 | by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter |
| 7974 | @samp{l}, specifying that the constant should be treated as a |
| 7975 | @code{long} value. |
| 7976 | |
| 7977 | @item |
| 7978 | Floating point constants are a sequence of digits, followed by a decimal |
| 7979 | point, followed by a sequence of digits, and optionally followed by an |
| 7980 | exponent. An exponent is of the form: |
| 7981 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another |
| 7982 | sequence of digits. The @samp{+} is optional for positive exponents. |
| 7983 | A floating-point constant may also end with a letter @samp{f} or |
| 7984 | @samp{F}, specifying that the constant should be treated as being of |
| 7985 | the @code{float} (as opposed to the default @code{double}) type; or with |
| 7986 | a letter @samp{l} or @samp{L}, which specifies a @code{long double} |
| 7987 | constant. |
| 7988 | |
| 7989 | @item |
| 7990 | Enumerated constants consist of enumerated identifiers, or their |
| 7991 | integral equivalents. |
| 7992 | |
| 7993 | @item |
| 7994 | Character constants are a single character surrounded by single quotes |
| 7995 | (@code{'}), or a number---the ordinal value of the corresponding character |
| 7996 | (usually its @sc{ascii} value). Within quotes, the single character may |
| 7997 | be represented by a letter or by @dfn{escape sequences}, which are of |
| 7998 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation |
| 7999 | of the character's ordinal value; or of the form @samp{\@var{x}}, where |
| 8000 | @samp{@var{x}} is a predefined special character---for example, |
| 8001 | @samp{\n} for newline. |
| 8002 | |
| 8003 | @item |
| 8004 | String constants are a sequence of character constants surrounded by |
| 8005 | double quotes (@code{"}). Any valid character constant (as described |
| 8006 | above) may appear. Double quotes within the string must be preceded by |
| 8007 | a backslash, so for instance @samp{"a\"b'c"} is a string of five |
| 8008 | characters. |
| 8009 | |
| 8010 | @item |
| 8011 | Pointer constants are an integral value. You can also write pointers |
| 8012 | to constants using the C operator @samp{&}. |
| 8013 | |
| 8014 | @item |
| 8015 | Array constants are comma-separated lists surrounded by braces @samp{@{} |
| 8016 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of |
| 8017 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, |
| 8018 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. |
| 8019 | @end itemize |
| 8020 | |
| 8021 | @menu |
| 8022 | * C plus plus expressions:: |
| 8023 | * C Defaults:: |
| 8024 | * C Checks:: |
| 8025 | |
| 8026 | * Debugging C:: |
| 8027 | @end menu |
| 8028 | |
| 8029 | @node C plus plus expressions |
| 8030 | @subsubsection C@t{++} expressions |
| 8031 | |
| 8032 | @cindex expressions in C@t{++} |
| 8033 | @value{GDBN} expression handling can interpret most C@t{++} expressions. |
| 8034 | |
| 8035 | @cindex C@t{++} support, not in @sc{coff} |
| 8036 | @cindex @sc{coff} versus C@t{++} |
| 8037 | @cindex C@t{++} and object formats |
| 8038 | @cindex object formats and C@t{++} |
| 8039 | @cindex a.out and C@t{++} |
| 8040 | @cindex @sc{ecoff} and C@t{++} |
| 8041 | @cindex @sc{xcoff} and C@t{++} |
| 8042 | @cindex @sc{elf}/stabs and C@t{++} |
| 8043 | @cindex @sc{elf}/@sc{dwarf} and C@t{++} |
| 8044 | @c FIXME!! GDB may eventually be able to debug C++ using DWARF; check |
| 8045 | @c periodically whether this has happened... |
| 8046 | @quotation |
| 8047 | @emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use the |
| 8048 | proper compiler. Typically, C@t{++} debugging depends on the use of |
| 8049 | additional debugging information in the symbol table, and thus requires |
| 8050 | special support. In particular, if your compiler generates a.out, MIPS |
| 8051 | @sc{ecoff}, RS/6000 @sc{xcoff}, or @sc{elf} with stabs extensions to the |
| 8052 | symbol table, these facilities are all available. (With @sc{gnu} CC, |
| 8053 | you can use the @samp{-gstabs} option to request stabs debugging |
| 8054 | extensions explicitly.) Where the object code format is standard |
| 8055 | @sc{coff} or @sc{dwarf} in @sc{elf}, on the other hand, most of the C@t{++} |
| 8056 | support in @value{GDBN} does @emph{not} work. |
| 8057 | @end quotation |
| 8058 | |
| 8059 | @enumerate |
| 8060 | |
| 8061 | @cindex member functions |
| 8062 | @item |
| 8063 | Member function calls are allowed; you can use expressions like |
| 8064 | |
| 8065 | @smallexample |
| 8066 | count = aml->GetOriginal(x, y) |
| 8067 | @end smallexample |
| 8068 | |
| 8069 | @vindex this@r{, inside C@t{++} member functions} |
| 8070 | @cindex namespace in C@t{++} |
| 8071 | @item |
| 8072 | While a member function is active (in the selected stack frame), your |
| 8073 | expressions have the same namespace available as the member function; |
| 8074 | that is, @value{GDBN} allows implicit references to the class instance |
| 8075 | pointer @code{this} following the same rules as C@t{++}. |
| 8076 | |
| 8077 | @cindex call overloaded functions |
| 8078 | @cindex overloaded functions, calling |
| 8079 | @cindex type conversions in C@t{++} |
| 8080 | @item |
| 8081 | You can call overloaded functions; @value{GDBN} resolves the function |
| 8082 | call to the right definition, with some restrictions. @value{GDBN} does not |
| 8083 | perform overload resolution involving user-defined type conversions, |
| 8084 | calls to constructors, or instantiations of templates that do not exist |
| 8085 | in the program. It also cannot handle ellipsis argument lists or |
| 8086 | default arguments. |
| 8087 | |
| 8088 | It does perform integral conversions and promotions, floating-point |
| 8089 | promotions, arithmetic conversions, pointer conversions, conversions of |
| 8090 | class objects to base classes, and standard conversions such as those of |
| 8091 | functions or arrays to pointers; it requires an exact match on the |
| 8092 | number of function arguments. |
| 8093 | |
| 8094 | Overload resolution is always performed, unless you have specified |
| 8095 | @code{set overload-resolution off}. @xref{Debugging C plus plus, |
| 8096 | ,@value{GDBN} features for C@t{++}}. |
| 8097 | |
| 8098 | You must specify @code{set overload-resolution off} in order to use an |
| 8099 | explicit function signature to call an overloaded function, as in |
| 8100 | @smallexample |
| 8101 | p 'foo(char,int)'('x', 13) |
| 8102 | @end smallexample |
| 8103 | |
| 8104 | The @value{GDBN} command-completion facility can simplify this; |
| 8105 | see @ref{Completion, ,Command completion}. |
| 8106 | |
| 8107 | @cindex reference declarations |
| 8108 | @item |
| 8109 | @value{GDBN} understands variables declared as C@t{++} references; you can use |
| 8110 | them in expressions just as you do in C@t{++} source---they are automatically |
| 8111 | dereferenced. |
| 8112 | |
| 8113 | In the parameter list shown when @value{GDBN} displays a frame, the values of |
| 8114 | reference variables are not displayed (unlike other variables); this |
| 8115 | avoids clutter, since references are often used for large structures. |
| 8116 | The @emph{address} of a reference variable is always shown, unless |
| 8117 | you have specified @samp{set print address off}. |
| 8118 | |
| 8119 | @item |
| 8120 | @value{GDBN} supports the C@t{++} name resolution operator @code{::}---your |
| 8121 | expressions can use it just as expressions in your program do. Since |
| 8122 | one scope may be defined in another, you can use @code{::} repeatedly if |
| 8123 | necessary, for example in an expression like |
| 8124 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows |
| 8125 | resolving name scope by reference to source files, in both C and C@t{++} |
| 8126 | debugging (@pxref{Variables, ,Program variables}). |
| 8127 | @end enumerate |
| 8128 | |
| 8129 | In addition, when used with HP's C@t{++} compiler, @value{GDBN} supports |
| 8130 | calling virtual functions correctly, printing out virtual bases of |
| 8131 | objects, calling functions in a base subobject, casting objects, and |
| 8132 | invoking user-defined operators. |
| 8133 | |
| 8134 | @node C Defaults |
| 8135 | @subsubsection C and C@t{++} defaults |
| 8136 | |
| 8137 | @cindex C and C@t{++} defaults |
| 8138 | |
| 8139 | If you allow @value{GDBN} to set type and range checking automatically, they |
| 8140 | both default to @code{off} whenever the working language changes to |
| 8141 | C or C@t{++}. This happens regardless of whether you or @value{GDBN} |
| 8142 | selects the working language. |
| 8143 | |
| 8144 | If you allow @value{GDBN} to set the language automatically, it |
| 8145 | recognizes source files whose names end with @file{.c}, @file{.C}, or |
| 8146 | @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of |
| 8147 | these files, it sets the working language to C or C@t{++}. |
| 8148 | @xref{Automatically, ,Having @value{GDBN} infer the source language}, |
| 8149 | for further details. |
| 8150 | |
| 8151 | @c Type checking is (a) primarily motivated by Modula-2, and (b) |
| 8152 | @c unimplemented. If (b) changes, it might make sense to let this node |
| 8153 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. |
| 8154 | |
| 8155 | @node C Checks |
| 8156 | @subsubsection C and C@t{++} type and range checks |
| 8157 | |
| 8158 | @cindex C and C@t{++} checks |
| 8159 | |
| 8160 | By default, when @value{GDBN} parses C or C@t{++} expressions, type checking |
| 8161 | is not used. However, if you turn type checking on, @value{GDBN} |
| 8162 | considers two variables type equivalent if: |
| 8163 | |
| 8164 | @itemize @bullet |
| 8165 | @item |
| 8166 | The two variables are structured and have the same structure, union, or |
| 8167 | enumerated tag. |
| 8168 | |
| 8169 | @item |
| 8170 | The two variables have the same type name, or types that have been |
| 8171 | declared equivalent through @code{typedef}. |
| 8172 | |
| 8173 | @ignore |
| 8174 | @c leaving this out because neither J Gilmore nor R Pesch understand it. |
| 8175 | @c FIXME--beers? |
| 8176 | @item |
| 8177 | The two @code{struct}, @code{union}, or @code{enum} variables are |
| 8178 | declared in the same declaration. (Note: this may not be true for all C |
| 8179 | compilers.) |
| 8180 | @end ignore |
| 8181 | @end itemize |
| 8182 | |
| 8183 | Range checking, if turned on, is done on mathematical operations. Array |
| 8184 | indices are not checked, since they are often used to index a pointer |
| 8185 | that is not itself an array. |
| 8186 | |
| 8187 | @node Debugging C |
| 8188 | @subsubsection @value{GDBN} and C |
| 8189 | |
| 8190 | The @code{set print union} and @code{show print union} commands apply to |
| 8191 | the @code{union} type. When set to @samp{on}, any @code{union} that is |
| 8192 | inside a @code{struct} or @code{class} is also printed. Otherwise, it |
| 8193 | appears as @samp{@{...@}}. |
| 8194 | |
| 8195 | The @code{@@} operator aids in the debugging of dynamic arrays, formed |
| 8196 | with pointers and a memory allocation function. @xref{Expressions, |
| 8197 | ,Expressions}. |
| 8198 | |
| 8199 | @menu |
| 8200 | * Debugging C plus plus:: |
| 8201 | @end menu |
| 8202 | |
| 8203 | @node Debugging C plus plus |
| 8204 | @subsubsection @value{GDBN} features for C@t{++} |
| 8205 | |
| 8206 | @cindex commands for C@t{++} |
| 8207 | |
| 8208 | Some @value{GDBN} commands are particularly useful with C@t{++}, and some are |
| 8209 | designed specifically for use with C@t{++}. Here is a summary: |
| 8210 | |
| 8211 | @table @code |
| 8212 | @cindex break in overloaded functions |
| 8213 | @item @r{breakpoint menus} |
| 8214 | When you want a breakpoint in a function whose name is overloaded, |
| 8215 | @value{GDBN} breakpoint menus help you specify which function definition |
| 8216 | you want. @xref{Breakpoint Menus,,Breakpoint menus}. |
| 8217 | |
| 8218 | @cindex overloading in C@t{++} |
| 8219 | @item rbreak @var{regex} |
| 8220 | Setting breakpoints using regular expressions is helpful for setting |
| 8221 | breakpoints on overloaded functions that are not members of any special |
| 8222 | classes. |
| 8223 | @xref{Set Breaks, ,Setting breakpoints}. |
| 8224 | |
| 8225 | @cindex C@t{++} exception handling |
| 8226 | @item catch throw |
| 8227 | @itemx catch catch |
| 8228 | Debug C@t{++} exception handling using these commands. @xref{Set |
| 8229 | Catchpoints, , Setting catchpoints}. |
| 8230 | |
| 8231 | @cindex inheritance |
| 8232 | @item ptype @var{typename} |
| 8233 | Print inheritance relationships as well as other information for type |
| 8234 | @var{typename}. |
| 8235 | @xref{Symbols, ,Examining the Symbol Table}. |
| 8236 | |
| 8237 | @cindex C@t{++} symbol display |
| 8238 | @item set print demangle |
| 8239 | @itemx show print demangle |
| 8240 | @itemx set print asm-demangle |
| 8241 | @itemx show print asm-demangle |
| 8242 | Control whether C@t{++} symbols display in their source form, both when |
| 8243 | displaying code as C@t{++} source and when displaying disassemblies. |
| 8244 | @xref{Print Settings, ,Print settings}. |
| 8245 | |
| 8246 | @item set print object |
| 8247 | @itemx show print object |
| 8248 | Choose whether to print derived (actual) or declared types of objects. |
| 8249 | @xref{Print Settings, ,Print settings}. |
| 8250 | |
| 8251 | @item set print vtbl |
| 8252 | @itemx show print vtbl |
| 8253 | Control the format for printing virtual function tables. |
| 8254 | @xref{Print Settings, ,Print settings}. |
| 8255 | (The @code{vtbl} commands do not work on programs compiled with the HP |
| 8256 | ANSI C@t{++} compiler (@code{aCC}).) |
| 8257 | |
| 8258 | @kindex set overload-resolution |
| 8259 | @cindex overloaded functions, overload resolution |
| 8260 | @item set overload-resolution on |
| 8261 | Enable overload resolution for C@t{++} expression evaluation. The default |
| 8262 | is on. For overloaded functions, @value{GDBN} evaluates the arguments |
| 8263 | and searches for a function whose signature matches the argument types, |
| 8264 | using the standard C@t{++} conversion rules (see @ref{C plus plus expressions, ,C@t{++} |
| 8265 | expressions}, for details). If it cannot find a match, it emits a |
| 8266 | message. |
| 8267 | |
| 8268 | @item set overload-resolution off |
| 8269 | Disable overload resolution for C@t{++} expression evaluation. For |
| 8270 | overloaded functions that are not class member functions, @value{GDBN} |
| 8271 | chooses the first function of the specified name that it finds in the |
| 8272 | symbol table, whether or not its arguments are of the correct type. For |
| 8273 | overloaded functions that are class member functions, @value{GDBN} |
| 8274 | searches for a function whose signature @emph{exactly} matches the |
| 8275 | argument types. |
| 8276 | |
| 8277 | @item @r{Overloaded symbol names} |
| 8278 | You can specify a particular definition of an overloaded symbol, using |
| 8279 | the same notation that is used to declare such symbols in C@t{++}: type |
| 8280 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can |
| 8281 | also use the @value{GDBN} command-line word completion facilities to list the |
| 8282 | available choices, or to finish the type list for you. |
| 8283 | @xref{Completion,, Command completion}, for details on how to do this. |
| 8284 | @end table |
| 8285 | |
| 8286 | @node Modula-2 |
| 8287 | @subsection Modula-2 |
| 8288 | |
| 8289 | @cindex Modula-2, @value{GDBN} support |
| 8290 | |
| 8291 | The extensions made to @value{GDBN} to support Modula-2 only support |
| 8292 | output from the @sc{gnu} Modula-2 compiler (which is currently being |
| 8293 | developed). Other Modula-2 compilers are not currently supported, and |
| 8294 | attempting to debug executables produced by them is most likely |
| 8295 | to give an error as @value{GDBN} reads in the executable's symbol |
| 8296 | table. |
| 8297 | |
| 8298 | @cindex expressions in Modula-2 |
| 8299 | @menu |
| 8300 | * M2 Operators:: Built-in operators |
| 8301 | * Built-In Func/Proc:: Built-in functions and procedures |
| 8302 | * M2 Constants:: Modula-2 constants |
| 8303 | * M2 Defaults:: Default settings for Modula-2 |
| 8304 | * Deviations:: Deviations from standard Modula-2 |
| 8305 | * M2 Checks:: Modula-2 type and range checks |
| 8306 | * M2 Scope:: The scope operators @code{::} and @code{.} |
| 8307 | * GDB/M2:: @value{GDBN} and Modula-2 |
| 8308 | @end menu |
| 8309 | |
| 8310 | @node M2 Operators |
| 8311 | @subsubsection Operators |
| 8312 | @cindex Modula-2 operators |
| 8313 | |
| 8314 | Operators must be defined on values of specific types. For instance, |
| 8315 | @code{+} is defined on numbers, but not on structures. Operators are |
| 8316 | often defined on groups of types. For the purposes of Modula-2, the |
| 8317 | following definitions hold: |
| 8318 | |
| 8319 | @itemize @bullet |
| 8320 | |
| 8321 | @item |
| 8322 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and |
| 8323 | their subranges. |
| 8324 | |
| 8325 | @item |
| 8326 | @emph{Character types} consist of @code{CHAR} and its subranges. |
| 8327 | |
| 8328 | @item |
| 8329 | @emph{Floating-point types} consist of @code{REAL}. |
| 8330 | |
| 8331 | @item |
| 8332 | @emph{Pointer types} consist of anything declared as @code{POINTER TO |
| 8333 | @var{type}}. |
| 8334 | |
| 8335 | @item |
| 8336 | @emph{Scalar types} consist of all of the above. |
| 8337 | |
| 8338 | @item |
| 8339 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. |
| 8340 | |
| 8341 | @item |
| 8342 | @emph{Boolean types} consist of @code{BOOLEAN}. |
| 8343 | @end itemize |
| 8344 | |
| 8345 | @noindent |
| 8346 | The following operators are supported, and appear in order of |
| 8347 | increasing precedence: |
| 8348 | |
| 8349 | @table @code |
| 8350 | @item , |
| 8351 | Function argument or array index separator. |
| 8352 | |
| 8353 | @item := |
| 8354 | Assignment. The value of @var{var} @code{:=} @var{value} is |
| 8355 | @var{value}. |
| 8356 | |
| 8357 | @item <@r{, }> |
| 8358 | Less than, greater than on integral, floating-point, or enumerated |
| 8359 | types. |
| 8360 | |
| 8361 | @item <=@r{, }>= |
| 8362 | Less than or equal to, greater than or equal to |
| 8363 | on integral, floating-point and enumerated types, or set inclusion on |
| 8364 | set types. Same precedence as @code{<}. |
| 8365 | |
| 8366 | @item =@r{, }<>@r{, }# |
| 8367 | Equality and two ways of expressing inequality, valid on scalar types. |
| 8368 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is |
| 8369 | available for inequality, since @code{#} conflicts with the script |
| 8370 | comment character. |
| 8371 | |
| 8372 | @item IN |
| 8373 | Set membership. Defined on set types and the types of their members. |
| 8374 | Same precedence as @code{<}. |
| 8375 | |
| 8376 | @item OR |
| 8377 | Boolean disjunction. Defined on boolean types. |
| 8378 | |
| 8379 | @item AND@r{, }& |
| 8380 | Boolean conjunction. Defined on boolean types. |
| 8381 | |
| 8382 | @item @@ |
| 8383 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
| 8384 | |
| 8385 | @item +@r{, }- |
| 8386 | Addition and subtraction on integral and floating-point types, or union |
| 8387 | and difference on set types. |
| 8388 | |
| 8389 | @item * |
| 8390 | Multiplication on integral and floating-point types, or set intersection |
| 8391 | on set types. |
| 8392 | |
| 8393 | @item / |
| 8394 | Division on floating-point types, or symmetric set difference on set |
| 8395 | types. Same precedence as @code{*}. |
| 8396 | |
| 8397 | @item DIV@r{, }MOD |
| 8398 | Integer division and remainder. Defined on integral types. Same |
| 8399 | precedence as @code{*}. |
| 8400 | |
| 8401 | @item - |
| 8402 | Negative. Defined on @code{INTEGER} and @code{REAL} data. |
| 8403 | |
| 8404 | @item ^ |
| 8405 | Pointer dereferencing. Defined on pointer types. |
| 8406 | |
| 8407 | @item NOT |
| 8408 | Boolean negation. Defined on boolean types. Same precedence as |
| 8409 | @code{^}. |
| 8410 | |
| 8411 | @item . |
| 8412 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same |
| 8413 | precedence as @code{^}. |
| 8414 | |
| 8415 | @item [] |
| 8416 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. |
| 8417 | |
| 8418 | @item () |
| 8419 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence |
| 8420 | as @code{^}. |
| 8421 | |
| 8422 | @item ::@r{, }. |
| 8423 | @value{GDBN} and Modula-2 scope operators. |
| 8424 | @end table |
| 8425 | |
| 8426 | @quotation |
| 8427 | @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} |
| 8428 | treats the use of the operator @code{IN}, or the use of operators |
| 8429 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, |
| 8430 | @code{<=}, and @code{>=} on sets as an error. |
| 8431 | @end quotation |
| 8432 | |
| 8433 | |
| 8434 | @node Built-In Func/Proc |
| 8435 | @subsubsection Built-in functions and procedures |
| 8436 | @cindex Modula-2 built-ins |
| 8437 | |
| 8438 | Modula-2 also makes available several built-in procedures and functions. |
| 8439 | In describing these, the following metavariables are used: |
| 8440 | |
| 8441 | @table @var |
| 8442 | |
| 8443 | @item a |
| 8444 | represents an @code{ARRAY} variable. |
| 8445 | |
| 8446 | @item c |
| 8447 | represents a @code{CHAR} constant or variable. |
| 8448 | |
| 8449 | @item i |
| 8450 | represents a variable or constant of integral type. |
| 8451 | |
| 8452 | @item m |
| 8453 | represents an identifier that belongs to a set. Generally used in the |
| 8454 | same function with the metavariable @var{s}. The type of @var{s} should |
| 8455 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). |
| 8456 | |
| 8457 | @item n |
| 8458 | represents a variable or constant of integral or floating-point type. |
| 8459 | |
| 8460 | @item r |
| 8461 | represents a variable or constant of floating-point type. |
| 8462 | |
| 8463 | @item t |
| 8464 | represents a type. |
| 8465 | |
| 8466 | @item v |
| 8467 | represents a variable. |
| 8468 | |
| 8469 | @item x |
| 8470 | represents a variable or constant of one of many types. See the |
| 8471 | explanation of the function for details. |
| 8472 | @end table |
| 8473 | |
| 8474 | All Modula-2 built-in procedures also return a result, described below. |
| 8475 | |
| 8476 | @table @code |
| 8477 | @item ABS(@var{n}) |
| 8478 | Returns the absolute value of @var{n}. |
| 8479 | |
| 8480 | @item CAP(@var{c}) |
| 8481 | If @var{c} is a lower case letter, it returns its upper case |
| 8482 | equivalent, otherwise it returns its argument. |
| 8483 | |
| 8484 | @item CHR(@var{i}) |
| 8485 | Returns the character whose ordinal value is @var{i}. |
| 8486 | |
| 8487 | @item DEC(@var{v}) |
| 8488 | Decrements the value in the variable @var{v} by one. Returns the new value. |
| 8489 | |
| 8490 | @item DEC(@var{v},@var{i}) |
| 8491 | Decrements the value in the variable @var{v} by @var{i}. Returns the |
| 8492 | new value. |
| 8493 | |
| 8494 | @item EXCL(@var{m},@var{s}) |
| 8495 | Removes the element @var{m} from the set @var{s}. Returns the new |
| 8496 | set. |
| 8497 | |
| 8498 | @item FLOAT(@var{i}) |
| 8499 | Returns the floating point equivalent of the integer @var{i}. |
| 8500 | |
| 8501 | @item HIGH(@var{a}) |
| 8502 | Returns the index of the last member of @var{a}. |
| 8503 | |
| 8504 | @item INC(@var{v}) |
| 8505 | Increments the value in the variable @var{v} by one. Returns the new value. |
| 8506 | |
| 8507 | @item INC(@var{v},@var{i}) |
| 8508 | Increments the value in the variable @var{v} by @var{i}. Returns the |
| 8509 | new value. |
| 8510 | |
| 8511 | @item INCL(@var{m},@var{s}) |
| 8512 | Adds the element @var{m} to the set @var{s} if it is not already |
| 8513 | there. Returns the new set. |
| 8514 | |
| 8515 | @item MAX(@var{t}) |
| 8516 | Returns the maximum value of the type @var{t}. |
| 8517 | |
| 8518 | @item MIN(@var{t}) |
| 8519 | Returns the minimum value of the type @var{t}. |
| 8520 | |
| 8521 | @item ODD(@var{i}) |
| 8522 | Returns boolean TRUE if @var{i} is an odd number. |
| 8523 | |
| 8524 | @item ORD(@var{x}) |
| 8525 | Returns the ordinal value of its argument. For example, the ordinal |
| 8526 | value of a character is its @sc{ascii} value (on machines supporting the |
| 8527 | @sc{ascii} character set). @var{x} must be of an ordered type, which include |
| 8528 | integral, character and enumerated types. |
| 8529 | |
| 8530 | @item SIZE(@var{x}) |
| 8531 | Returns the size of its argument. @var{x} can be a variable or a type. |
| 8532 | |
| 8533 | @item TRUNC(@var{r}) |
| 8534 | Returns the integral part of @var{r}. |
| 8535 | |
| 8536 | @item VAL(@var{t},@var{i}) |
| 8537 | Returns the member of the type @var{t} whose ordinal value is @var{i}. |
| 8538 | @end table |
| 8539 | |
| 8540 | @quotation |
| 8541 | @emph{Warning:} Sets and their operations are not yet supported, so |
| 8542 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as |
| 8543 | an error. |
| 8544 | @end quotation |
| 8545 | |
| 8546 | @cindex Modula-2 constants |
| 8547 | @node M2 Constants |
| 8548 | @subsubsection Constants |
| 8549 | |
| 8550 | @value{GDBN} allows you to express the constants of Modula-2 in the following |
| 8551 | ways: |
| 8552 | |
| 8553 | @itemize @bullet |
| 8554 | |
| 8555 | @item |
| 8556 | Integer constants are simply a sequence of digits. When used in an |
| 8557 | expression, a constant is interpreted to be type-compatible with the |
| 8558 | rest of the expression. Hexadecimal integers are specified by a |
| 8559 | trailing @samp{H}, and octal integers by a trailing @samp{B}. |
| 8560 | |
| 8561 | @item |
| 8562 | Floating point constants appear as a sequence of digits, followed by a |
| 8563 | decimal point and another sequence of digits. An optional exponent can |
| 8564 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where |
| 8565 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the |
| 8566 | digits of the floating point constant must be valid decimal (base 10) |
| 8567 | digits. |
| 8568 | |
| 8569 | @item |
| 8570 | Character constants consist of a single character enclosed by a pair of |
| 8571 | like quotes, either single (@code{'}) or double (@code{"}). They may |
| 8572 | also be expressed by their ordinal value (their @sc{ascii} value, usually) |
| 8573 | followed by a @samp{C}. |
| 8574 | |
| 8575 | @item |
| 8576 | String constants consist of a sequence of characters enclosed by a |
| 8577 | pair of like quotes, either single (@code{'}) or double (@code{"}). |
| 8578 | Escape sequences in the style of C are also allowed. @xref{C |
| 8579 | Constants, ,C and C@t{++} constants}, for a brief explanation of escape |
| 8580 | sequences. |
| 8581 | |
| 8582 | @item |
| 8583 | Enumerated constants consist of an enumerated identifier. |
| 8584 | |
| 8585 | @item |
| 8586 | Boolean constants consist of the identifiers @code{TRUE} and |
| 8587 | @code{FALSE}. |
| 8588 | |
| 8589 | @item |
| 8590 | Pointer constants consist of integral values only. |
| 8591 | |
| 8592 | @item |
| 8593 | Set constants are not yet supported. |
| 8594 | @end itemize |
| 8595 | |
| 8596 | @node M2 Defaults |
| 8597 | @subsubsection Modula-2 defaults |
| 8598 | @cindex Modula-2 defaults |
| 8599 | |
| 8600 | If type and range checking are set automatically by @value{GDBN}, they |
| 8601 | both default to @code{on} whenever the working language changes to |
| 8602 | Modula-2. This happens regardless of whether you or @value{GDBN} |
| 8603 | selected the working language. |
| 8604 | |
| 8605 | If you allow @value{GDBN} to set the language automatically, then entering |
| 8606 | code compiled from a file whose name ends with @file{.mod} sets the |
| 8607 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set |
| 8608 | the language automatically}, for further details. |
| 8609 | |
| 8610 | @node Deviations |
| 8611 | @subsubsection Deviations from standard Modula-2 |
| 8612 | @cindex Modula-2, deviations from |
| 8613 | |
| 8614 | A few changes have been made to make Modula-2 programs easier to debug. |
| 8615 | This is done primarily via loosening its type strictness: |
| 8616 | |
| 8617 | @itemize @bullet |
| 8618 | @item |
| 8619 | Unlike in standard Modula-2, pointer constants can be formed by |
| 8620 | integers. This allows you to modify pointer variables during |
| 8621 | debugging. (In standard Modula-2, the actual address contained in a |
| 8622 | pointer variable is hidden from you; it can only be modified |
| 8623 | through direct assignment to another pointer variable or expression that |
| 8624 | returned a pointer.) |
| 8625 | |
| 8626 | @item |
| 8627 | C escape sequences can be used in strings and characters to represent |
| 8628 | non-printable characters. @value{GDBN} prints out strings with these |
| 8629 | escape sequences embedded. Single non-printable characters are |
| 8630 | printed using the @samp{CHR(@var{nnn})} format. |
| 8631 | |
| 8632 | @item |
| 8633 | The assignment operator (@code{:=}) returns the value of its right-hand |
| 8634 | argument. |
| 8635 | |
| 8636 | @item |
| 8637 | All built-in procedures both modify @emph{and} return their argument. |
| 8638 | @end itemize |
| 8639 | |
| 8640 | @node M2 Checks |
| 8641 | @subsubsection Modula-2 type and range checks |
| 8642 | @cindex Modula-2 checks |
| 8643 | |
| 8644 | @quotation |
| 8645 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or |
| 8646 | range checking. |
| 8647 | @end quotation |
| 8648 | @c FIXME remove warning when type/range checks added |
| 8649 | |
| 8650 | @value{GDBN} considers two Modula-2 variables type equivalent if: |
| 8651 | |
| 8652 | @itemize @bullet |
| 8653 | @item |
| 8654 | They are of types that have been declared equivalent via a @code{TYPE |
| 8655 | @var{t1} = @var{t2}} statement |
| 8656 | |
| 8657 | @item |
| 8658 | They have been declared on the same line. (Note: This is true of the |
| 8659 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) |
| 8660 | @end itemize |
| 8661 | |
| 8662 | As long as type checking is enabled, any attempt to combine variables |
| 8663 | whose types are not equivalent is an error. |
| 8664 | |
| 8665 | Range checking is done on all mathematical operations, assignment, array |
| 8666 | index bounds, and all built-in functions and procedures. |
| 8667 | |
| 8668 | @node M2 Scope |
| 8669 | @subsubsection The scope operators @code{::} and @code{.} |
| 8670 | @cindex scope |
| 8671 | @cindex @code{.}, Modula-2 scope operator |
| 8672 | @cindex colon, doubled as scope operator |
| 8673 | @ifinfo |
| 8674 | @vindex colon-colon@r{, in Modula-2} |
| 8675 | @c Info cannot handle :: but TeX can. |
| 8676 | @end ifinfo |
| 8677 | @iftex |
| 8678 | @vindex ::@r{, in Modula-2} |
| 8679 | @end iftex |
| 8680 | |
| 8681 | There are a few subtle differences between the Modula-2 scope operator |
| 8682 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have |
| 8683 | similar syntax: |
| 8684 | |
| 8685 | @smallexample |
| 8686 | |
| 8687 | @var{module} . @var{id} |
| 8688 | @var{scope} :: @var{id} |
| 8689 | @end smallexample |
| 8690 | |
| 8691 | @noindent |
| 8692 | where @var{scope} is the name of a module or a procedure, |
| 8693 | @var{module} the name of a module, and @var{id} is any declared |
| 8694 | identifier within your program, except another module. |
| 8695 | |
| 8696 | Using the @code{::} operator makes @value{GDBN} search the scope |
| 8697 | specified by @var{scope} for the identifier @var{id}. If it is not |
| 8698 | found in the specified scope, then @value{GDBN} searches all scopes |
| 8699 | enclosing the one specified by @var{scope}. |
| 8700 | |
| 8701 | Using the @code{.} operator makes @value{GDBN} search the current scope for |
| 8702 | the identifier specified by @var{id} that was imported from the |
| 8703 | definition module specified by @var{module}. With this operator, it is |
| 8704 | an error if the identifier @var{id} was not imported from definition |
| 8705 | module @var{module}, or if @var{id} is not an identifier in |
| 8706 | @var{module}. |
| 8707 | |
| 8708 | @node GDB/M2 |
| 8709 | @subsubsection @value{GDBN} and Modula-2 |
| 8710 | |
| 8711 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. |
| 8712 | Five subcommands of @code{set print} and @code{show print} apply |
| 8713 | specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle}, |
| 8714 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four |
| 8715 | apply to C@t{++}, and the last to the C @code{union} type, which has no direct |
| 8716 | analogue in Modula-2. |
| 8717 | |
| 8718 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available |
| 8719 | with any language, is not useful with Modula-2. Its |
| 8720 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be |
| 8721 | created in Modula-2 as they can in C or C@t{++}. However, because an |
| 8722 | address can be specified by an integral constant, the construct |
| 8723 | @samp{@{@var{type}@}@var{adrexp}} is still useful. |
| 8724 | |
| 8725 | @cindex @code{#} in Modula-2 |
| 8726 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is |
| 8727 | interpreted as the beginning of a comment. Use @code{<>} instead. |
| 8728 | |
| 8729 | @node Symbols |
| 8730 | @chapter Examining the Symbol Table |
| 8731 | |
| 8732 | The commands described in this chapter allow you to inquire about the |
| 8733 | symbols (names of variables, functions and types) defined in your |
| 8734 | program. This information is inherent in the text of your program and |
| 8735 | does not change as your program executes. @value{GDBN} finds it in your |
| 8736 | program's symbol table, in the file indicated when you started @value{GDBN} |
| 8737 | (@pxref{File Options, ,Choosing files}), or by one of the |
| 8738 | file-management commands (@pxref{Files, ,Commands to specify files}). |
| 8739 | |
| 8740 | @cindex symbol names |
| 8741 | @cindex names of symbols |
| 8742 | @cindex quoting names |
| 8743 | Occasionally, you may need to refer to symbols that contain unusual |
| 8744 | characters, which @value{GDBN} ordinarily treats as word delimiters. The |
| 8745 | most frequent case is in referring to static variables in other |
| 8746 | source files (@pxref{Variables,,Program variables}). File names |
| 8747 | are recorded in object files as debugging symbols, but @value{GDBN} would |
| 8748 | ordinarily parse a typical file name, like @file{foo.c}, as the three words |
| 8749 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize |
| 8750 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, |
| 8751 | |
| 8752 | @smallexample |
| 8753 | p 'foo.c'::x |
| 8754 | @end smallexample |
| 8755 | |
| 8756 | @noindent |
| 8757 | looks up the value of @code{x} in the scope of the file @file{foo.c}. |
| 8758 | |
| 8759 | @table @code |
| 8760 | @kindex info address |
| 8761 | @cindex address of a symbol |
| 8762 | @item info address @var{symbol} |
| 8763 | Describe where the data for @var{symbol} is stored. For a register |
| 8764 | variable, this says which register it is kept in. For a non-register |
| 8765 | local variable, this prints the stack-frame offset at which the variable |
| 8766 | is always stored. |
| 8767 | |
| 8768 | Note the contrast with @samp{print &@var{symbol}}, which does not work |
| 8769 | at all for a register variable, and for a stack local variable prints |
| 8770 | the exact address of the current instantiation of the variable. |
| 8771 | |
| 8772 | @kindex info symbol |
| 8773 | @cindex symbol from address |
| 8774 | @item info symbol @var{addr} |
| 8775 | Print the name of a symbol which is stored at the address @var{addr}. |
| 8776 | If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the |
| 8777 | nearest symbol and an offset from it: |
| 8778 | |
| 8779 | @smallexample |
| 8780 | (@value{GDBP}) info symbol 0x54320 |
| 8781 | _initialize_vx + 396 in section .text |
| 8782 | @end smallexample |
| 8783 | |
| 8784 | @noindent |
| 8785 | This is the opposite of the @code{info address} command. You can use |
| 8786 | it to find out the name of a variable or a function given its address. |
| 8787 | |
| 8788 | @kindex whatis |
| 8789 | @item whatis @var{expr} |
| 8790 | Print the data type of expression @var{expr}. @var{expr} is not |
| 8791 | actually evaluated, and any side-effecting operations (such as |
| 8792 | assignments or function calls) inside it do not take place. |
| 8793 | @xref{Expressions, ,Expressions}. |
| 8794 | |
| 8795 | @item whatis |
| 8796 | Print the data type of @code{$}, the last value in the value history. |
| 8797 | |
| 8798 | @kindex ptype |
| 8799 | @item ptype @var{typename} |
| 8800 | Print a description of data type @var{typename}. @var{typename} may be |
| 8801 | the name of a type, or for C code it may have the form @samp{class |
| 8802 | @var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union |
| 8803 | @var{union-tag}} or @samp{enum @var{enum-tag}}. |
| 8804 | |
| 8805 | @item ptype @var{expr} |
| 8806 | @itemx ptype |
| 8807 | Print a description of the type of expression @var{expr}. @code{ptype} |
| 8808 | differs from @code{whatis} by printing a detailed description, instead |
| 8809 | of just the name of the type. |
| 8810 | |
| 8811 | For example, for this variable declaration: |
| 8812 | |
| 8813 | @smallexample |
| 8814 | struct complex @{double real; double imag;@} v; |
| 8815 | @end smallexample |
| 8816 | |
| 8817 | @noindent |
| 8818 | the two commands give this output: |
| 8819 | |
| 8820 | @smallexample |
| 8821 | @group |
| 8822 | (@value{GDBP}) whatis v |
| 8823 | type = struct complex |
| 8824 | (@value{GDBP}) ptype v |
| 8825 | type = struct complex @{ |
| 8826 | double real; |
| 8827 | double imag; |
| 8828 | @} |
| 8829 | @end group |
| 8830 | @end smallexample |
| 8831 | |
| 8832 | @noindent |
| 8833 | As with @code{whatis}, using @code{ptype} without an argument refers to |
| 8834 | the type of @code{$}, the last value in the value history. |
| 8835 | |
| 8836 | @kindex info types |
| 8837 | @item info types @var{regexp} |
| 8838 | @itemx info types |
| 8839 | Print a brief description of all types whose names match @var{regexp} |
| 8840 | (or all types in your program, if you supply no argument). Each |
| 8841 | complete typename is matched as though it were a complete line; thus, |
| 8842 | @samp{i type value} gives information on all types in your program whose |
| 8843 | names include the string @code{value}, but @samp{i type ^value$} gives |
| 8844 | information only on types whose complete name is @code{value}. |
| 8845 | |
| 8846 | This command differs from @code{ptype} in two ways: first, like |
| 8847 | @code{whatis}, it does not print a detailed description; second, it |
| 8848 | lists all source files where a type is defined. |
| 8849 | |
| 8850 | @kindex info scope |
| 8851 | @cindex local variables |
| 8852 | @item info scope @var{addr} |
| 8853 | List all the variables local to a particular scope. This command |
| 8854 | accepts a location---a function name, a source line, or an address |
| 8855 | preceded by a @samp{*}, and prints all the variables local to the |
| 8856 | scope defined by that location. For example: |
| 8857 | |
| 8858 | @smallexample |
| 8859 | (@value{GDBP}) @b{info scope command_line_handler} |
| 8860 | Scope for command_line_handler: |
| 8861 | Symbol rl is an argument at stack/frame offset 8, length 4. |
| 8862 | Symbol linebuffer is in static storage at address 0x150a18, length 4. |
| 8863 | Symbol linelength is in static storage at address 0x150a1c, length 4. |
| 8864 | Symbol p is a local variable in register $esi, length 4. |
| 8865 | Symbol p1 is a local variable in register $ebx, length 4. |
| 8866 | Symbol nline is a local variable in register $edx, length 4. |
| 8867 | Symbol repeat is a local variable at frame offset -8, length 4. |
| 8868 | @end smallexample |
| 8869 | |
| 8870 | @noindent |
| 8871 | This command is especially useful for determining what data to collect |
| 8872 | during a @dfn{trace experiment}, see @ref{Tracepoint Actions, |
| 8873 | collect}. |
| 8874 | |
| 8875 | @kindex info source |
| 8876 | @item info source |
| 8877 | Show information about the current source file---that is, the source file for |
| 8878 | the function containing the current point of execution: |
| 8879 | @itemize @bullet |
| 8880 | @item |
| 8881 | the name of the source file, and the directory containing it, |
| 8882 | @item |
| 8883 | the directory it was compiled in, |
| 8884 | @item |
| 8885 | its length, in lines, |
| 8886 | @item |
| 8887 | which programming language it is written in, |
| 8888 | @item |
| 8889 | whether the executable includes debugging information for that file, and |
| 8890 | if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and |
| 8891 | @item |
| 8892 | whether the debugging information includes information about |
| 8893 | preprocessor macros. |
| 8894 | @end itemize |
| 8895 | |
| 8896 | |
| 8897 | @kindex info sources |
| 8898 | @item info sources |
| 8899 | Print the names of all source files in your program for which there is |
| 8900 | debugging information, organized into two lists: files whose symbols |
| 8901 | have already been read, and files whose symbols will be read when needed. |
| 8902 | |
| 8903 | @kindex info functions |
| 8904 | @item info functions |
| 8905 | Print the names and data types of all defined functions. |
| 8906 | |
| 8907 | @item info functions @var{regexp} |
| 8908 | Print the names and data types of all defined functions |
| 8909 | whose names contain a match for regular expression @var{regexp}. |
| 8910 | Thus, @samp{info fun step} finds all functions whose names |
| 8911 | include @code{step}; @samp{info fun ^step} finds those whose names |
| 8912 | start with @code{step}. If a function name contains characters |
| 8913 | that conflict with the regular expression language (eg. |
| 8914 | @samp{operator*()}), they may be quoted with a backslash. |
| 8915 | |
| 8916 | @kindex info variables |
| 8917 | @item info variables |
| 8918 | Print the names and data types of all variables that are declared |
| 8919 | outside of functions (i.e.@: excluding local variables). |
| 8920 | |
| 8921 | @item info variables @var{regexp} |
| 8922 | Print the names and data types of all variables (except for local |
| 8923 | variables) whose names contain a match for regular expression |
| 8924 | @var{regexp}. |
| 8925 | |
| 8926 | @ignore |
| 8927 | This was never implemented. |
| 8928 | @kindex info methods |
| 8929 | @item info methods |
| 8930 | @itemx info methods @var{regexp} |
| 8931 | The @code{info methods} command permits the user to examine all defined |
| 8932 | methods within C@t{++} program, or (with the @var{regexp} argument) a |
| 8933 | specific set of methods found in the various C@t{++} classes. Many |
| 8934 | C@t{++} classes provide a large number of methods. Thus, the output |
| 8935 | from the @code{ptype} command can be overwhelming and hard to use. The |
| 8936 | @code{info-methods} command filters the methods, printing only those |
| 8937 | which match the regular-expression @var{regexp}. |
| 8938 | @end ignore |
| 8939 | |
| 8940 | @cindex reloading symbols |
| 8941 | Some systems allow individual object files that make up your program to |
| 8942 | be replaced without stopping and restarting your program. For example, |
| 8943 | in VxWorks you can simply recompile a defective object file and keep on |
| 8944 | running. If you are running on one of these systems, you can allow |
| 8945 | @value{GDBN} to reload the symbols for automatically relinked modules: |
| 8946 | |
| 8947 | @table @code |
| 8948 | @kindex set symbol-reloading |
| 8949 | @item set symbol-reloading on |
| 8950 | Replace symbol definitions for the corresponding source file when an |
| 8951 | object file with a particular name is seen again. |
| 8952 | |
| 8953 | @item set symbol-reloading off |
| 8954 | Do not replace symbol definitions when encountering object files of the |
| 8955 | same name more than once. This is the default state; if you are not |
| 8956 | running on a system that permits automatic relinking of modules, you |
| 8957 | should leave @code{symbol-reloading} off, since otherwise @value{GDBN} |
| 8958 | may discard symbols when linking large programs, that may contain |
| 8959 | several modules (from different directories or libraries) with the same |
| 8960 | name. |
| 8961 | |
| 8962 | @kindex show symbol-reloading |
| 8963 | @item show symbol-reloading |
| 8964 | Show the current @code{on} or @code{off} setting. |
| 8965 | @end table |
| 8966 | |
| 8967 | @kindex set opaque-type-resolution |
| 8968 | @item set opaque-type-resolution on |
| 8969 | Tell @value{GDBN} to resolve opaque types. An opaque type is a type |
| 8970 | declared as a pointer to a @code{struct}, @code{class}, or |
| 8971 | @code{union}---for example, @code{struct MyType *}---that is used in one |
| 8972 | source file although the full declaration of @code{struct MyType} is in |
| 8973 | another source file. The default is on. |
| 8974 | |
| 8975 | A change in the setting of this subcommand will not take effect until |
| 8976 | the next time symbols for a file are loaded. |
| 8977 | |
| 8978 | @item set opaque-type-resolution off |
| 8979 | Tell @value{GDBN} not to resolve opaque types. In this case, the type |
| 8980 | is printed as follows: |
| 8981 | @smallexample |
| 8982 | @{<no data fields>@} |
| 8983 | @end smallexample |
| 8984 | |
| 8985 | @kindex show opaque-type-resolution |
| 8986 | @item show opaque-type-resolution |
| 8987 | Show whether opaque types are resolved or not. |
| 8988 | |
| 8989 | @kindex maint print symbols |
| 8990 | @cindex symbol dump |
| 8991 | @kindex maint print psymbols |
| 8992 | @cindex partial symbol dump |
| 8993 | @item maint print symbols @var{filename} |
| 8994 | @itemx maint print psymbols @var{filename} |
| 8995 | @itemx maint print msymbols @var{filename} |
| 8996 | Write a dump of debugging symbol data into the file @var{filename}. |
| 8997 | These commands are used to debug the @value{GDBN} symbol-reading code. Only |
| 8998 | symbols with debugging data are included. If you use @samp{maint print |
| 8999 | symbols}, @value{GDBN} includes all the symbols for which it has already |
| 9000 | collected full details: that is, @var{filename} reflects symbols for |
| 9001 | only those files whose symbols @value{GDBN} has read. You can use the |
| 9002 | command @code{info sources} to find out which files these are. If you |
| 9003 | use @samp{maint print psymbols} instead, the dump shows information about |
| 9004 | symbols that @value{GDBN} only knows partially---that is, symbols defined in |
| 9005 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, |
| 9006 | @samp{maint print msymbols} dumps just the minimal symbol information |
| 9007 | required for each object file from which @value{GDBN} has read some symbols. |
| 9008 | @xref{Files, ,Commands to specify files}, for a discussion of how |
| 9009 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). |
| 9010 | @end table |
| 9011 | |
| 9012 | @node Altering |
| 9013 | @chapter Altering Execution |
| 9014 | |
| 9015 | Once you think you have found an error in your program, you might want to |
| 9016 | find out for certain whether correcting the apparent error would lead to |
| 9017 | correct results in the rest of the run. You can find the answer by |
| 9018 | experiment, using the @value{GDBN} features for altering execution of the |
| 9019 | program. |
| 9020 | |
| 9021 | For example, you can store new values into variables or memory |
| 9022 | locations, give your program a signal, restart it at a different |
| 9023 | address, or even return prematurely from a function. |
| 9024 | |
| 9025 | @menu |
| 9026 | * Assignment:: Assignment to variables |
| 9027 | * Jumping:: Continuing at a different address |
| 9028 | * Signaling:: Giving your program a signal |
| 9029 | * Returning:: Returning from a function |
| 9030 | * Calling:: Calling your program's functions |
| 9031 | * Patching:: Patching your program |
| 9032 | @end menu |
| 9033 | |
| 9034 | @node Assignment |
| 9035 | @section Assignment to variables |
| 9036 | |
| 9037 | @cindex assignment |
| 9038 | @cindex setting variables |
| 9039 | To alter the value of a variable, evaluate an assignment expression. |
| 9040 | @xref{Expressions, ,Expressions}. For example, |
| 9041 | |
| 9042 | @smallexample |
| 9043 | print x=4 |
| 9044 | @end smallexample |
| 9045 | |
| 9046 | @noindent |
| 9047 | stores the value 4 into the variable @code{x}, and then prints the |
| 9048 | value of the assignment expression (which is 4). |
| 9049 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more |
| 9050 | information on operators in supported languages. |
| 9051 | |
| 9052 | @kindex set variable |
| 9053 | @cindex variables, setting |
| 9054 | If you are not interested in seeing the value of the assignment, use the |
| 9055 | @code{set} command instead of the @code{print} command. @code{set} is |
| 9056 | really the same as @code{print} except that the expression's value is |
| 9057 | not printed and is not put in the value history (@pxref{Value History, |
| 9058 | ,Value history}). The expression is evaluated only for its effects. |
| 9059 | |
| 9060 | If the beginning of the argument string of the @code{set} command |
| 9061 | appears identical to a @code{set} subcommand, use the @code{set |
| 9062 | variable} command instead of just @code{set}. This command is identical |
| 9063 | to @code{set} except for its lack of subcommands. For example, if your |
| 9064 | program has a variable @code{width}, you get an error if you try to set |
| 9065 | a new value with just @samp{set width=13}, because @value{GDBN} has the |
| 9066 | command @code{set width}: |
| 9067 | |
| 9068 | @smallexample |
| 9069 | (@value{GDBP}) whatis width |
| 9070 | type = double |
| 9071 | (@value{GDBP}) p width |
| 9072 | $4 = 13 |
| 9073 | (@value{GDBP}) set width=47 |
| 9074 | Invalid syntax in expression. |
| 9075 | @end smallexample |
| 9076 | |
| 9077 | @noindent |
| 9078 | The invalid expression, of course, is @samp{=47}. In |
| 9079 | order to actually set the program's variable @code{width}, use |
| 9080 | |
| 9081 | @smallexample |
| 9082 | (@value{GDBP}) set var width=47 |
| 9083 | @end smallexample |
| 9084 | |
| 9085 | Because the @code{set} command has many subcommands that can conflict |
| 9086 | with the names of program variables, it is a good idea to use the |
| 9087 | @code{set variable} command instead of just @code{set}. For example, if |
| 9088 | your program has a variable @code{g}, you run into problems if you try |
| 9089 | to set a new value with just @samp{set g=4}, because @value{GDBN} has |
| 9090 | the command @code{set gnutarget}, abbreviated @code{set g}: |
| 9091 | |
| 9092 | @smallexample |
| 9093 | @group |
| 9094 | (@value{GDBP}) whatis g |
| 9095 | type = double |
| 9096 | (@value{GDBP}) p g |
| 9097 | $1 = 1 |
| 9098 | (@value{GDBP}) set g=4 |
| 9099 | (@value{GDBP}) p g |
| 9100 | $2 = 1 |
| 9101 | (@value{GDBP}) r |
| 9102 | The program being debugged has been started already. |
| 9103 | Start it from the beginning? (y or n) y |
| 9104 | Starting program: /home/smith/cc_progs/a.out |
| 9105 | "/home/smith/cc_progs/a.out": can't open to read symbols: |
| 9106 | Invalid bfd target. |
| 9107 | (@value{GDBP}) show g |
| 9108 | The current BFD target is "=4". |
| 9109 | @end group |
| 9110 | @end smallexample |
| 9111 | |
| 9112 | @noindent |
| 9113 | The program variable @code{g} did not change, and you silently set the |
| 9114 | @code{gnutarget} to an invalid value. In order to set the variable |
| 9115 | @code{g}, use |
| 9116 | |
| 9117 | @smallexample |
| 9118 | (@value{GDBP}) set var g=4 |
| 9119 | @end smallexample |
| 9120 | |
| 9121 | @value{GDBN} allows more implicit conversions in assignments than C; you can |
| 9122 | freely store an integer value into a pointer variable or vice versa, |
| 9123 | and you can convert any structure to any other structure that is the |
| 9124 | same length or shorter. |
| 9125 | @comment FIXME: how do structs align/pad in these conversions? |
| 9126 | @comment /doc@cygnus.com 18dec1990 |
| 9127 | |
| 9128 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} |
| 9129 | construct to generate a value of specified type at a specified address |
| 9130 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers |
| 9131 | to memory location @code{0x83040} as an integer (which implies a certain size |
| 9132 | and representation in memory), and |
| 9133 | |
| 9134 | @smallexample |
| 9135 | set @{int@}0x83040 = 4 |
| 9136 | @end smallexample |
| 9137 | |
| 9138 | @noindent |
| 9139 | stores the value 4 into that memory location. |
| 9140 | |
| 9141 | @node Jumping |
| 9142 | @section Continuing at a different address |
| 9143 | |
| 9144 | Ordinarily, when you continue your program, you do so at the place where |
| 9145 | it stopped, with the @code{continue} command. You can instead continue at |
| 9146 | an address of your own choosing, with the following commands: |
| 9147 | |
| 9148 | @table @code |
| 9149 | @kindex jump |
| 9150 | @item jump @var{linespec} |
| 9151 | Resume execution at line @var{linespec}. Execution stops again |
| 9152 | immediately if there is a breakpoint there. @xref{List, ,Printing |
| 9153 | source lines}, for a description of the different forms of |
| 9154 | @var{linespec}. It is common practice to use the @code{tbreak} command |
| 9155 | in conjunction with @code{jump}. @xref{Set Breaks, ,Setting |
| 9156 | breakpoints}. |
| 9157 | |
| 9158 | The @code{jump} command does not change the current stack frame, or |
| 9159 | the stack pointer, or the contents of any memory location or any |
| 9160 | register other than the program counter. If line @var{linespec} is in |
| 9161 | a different function from the one currently executing, the results may |
| 9162 | be bizarre if the two functions expect different patterns of arguments or |
| 9163 | of local variables. For this reason, the @code{jump} command requests |
| 9164 | confirmation if the specified line is not in the function currently |
| 9165 | executing. However, even bizarre results are predictable if you are |
| 9166 | well acquainted with the machine-language code of your program. |
| 9167 | |
| 9168 | @item jump *@var{address} |
| 9169 | Resume execution at the instruction at address @var{address}. |
| 9170 | @end table |
| 9171 | |
| 9172 | @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt. |
| 9173 | On many systems, you can get much the same effect as the @code{jump} |
| 9174 | command by storing a new value into the register @code{$pc}. The |
| 9175 | difference is that this does not start your program running; it only |
| 9176 | changes the address of where it @emph{will} run when you continue. For |
| 9177 | example, |
| 9178 | |
| 9179 | @smallexample |
| 9180 | set $pc = 0x485 |
| 9181 | @end smallexample |
| 9182 | |
| 9183 | @noindent |
| 9184 | makes the next @code{continue} command or stepping command execute at |
| 9185 | address @code{0x485}, rather than at the address where your program stopped. |
| 9186 | @xref{Continuing and Stepping, ,Continuing and stepping}. |
| 9187 | |
| 9188 | The most common occasion to use the @code{jump} command is to back |
| 9189 | up---perhaps with more breakpoints set---over a portion of a program |
| 9190 | that has already executed, in order to examine its execution in more |
| 9191 | detail. |
| 9192 | |
| 9193 | @c @group |
| 9194 | @node Signaling |
| 9195 | @section Giving your program a signal |
| 9196 | |
| 9197 | @table @code |
| 9198 | @kindex signal |
| 9199 | @item signal @var{signal} |
| 9200 | Resume execution where your program stopped, but immediately give it the |
| 9201 | signal @var{signal}. @var{signal} can be the name or the number of a |
| 9202 | signal. For example, on many systems @code{signal 2} and @code{signal |
| 9203 | SIGINT} are both ways of sending an interrupt signal. |
| 9204 | |
| 9205 | Alternatively, if @var{signal} is zero, continue execution without |
| 9206 | giving a signal. This is useful when your program stopped on account of |
| 9207 | a signal and would ordinary see the signal when resumed with the |
| 9208 | @code{continue} command; @samp{signal 0} causes it to resume without a |
| 9209 | signal. |
| 9210 | |
| 9211 | @code{signal} does not repeat when you press @key{RET} a second time |
| 9212 | after executing the command. |
| 9213 | @end table |
| 9214 | @c @end group |
| 9215 | |
| 9216 | Invoking the @code{signal} command is not the same as invoking the |
| 9217 | @code{kill} utility from the shell. Sending a signal with @code{kill} |
| 9218 | causes @value{GDBN} to decide what to do with the signal depending on |
| 9219 | the signal handling tables (@pxref{Signals}). The @code{signal} command |
| 9220 | passes the signal directly to your program. |
| 9221 | |
| 9222 | |
| 9223 | @node Returning |
| 9224 | @section Returning from a function |
| 9225 | |
| 9226 | @table @code |
| 9227 | @cindex returning from a function |
| 9228 | @kindex return |
| 9229 | @item return |
| 9230 | @itemx return @var{expression} |
| 9231 | You can cancel execution of a function call with the @code{return} |
| 9232 | command. If you give an |
| 9233 | @var{expression} argument, its value is used as the function's return |
| 9234 | value. |
| 9235 | @end table |
| 9236 | |
| 9237 | When you use @code{return}, @value{GDBN} discards the selected stack frame |
| 9238 | (and all frames within it). You can think of this as making the |
| 9239 | discarded frame return prematurely. If you wish to specify a value to |
| 9240 | be returned, give that value as the argument to @code{return}. |
| 9241 | |
| 9242 | This pops the selected stack frame (@pxref{Selection, ,Selecting a |
| 9243 | frame}), and any other frames inside of it, leaving its caller as the |
| 9244 | innermost remaining frame. That frame becomes selected. The |
| 9245 | specified value is stored in the registers used for returning values |
| 9246 | of functions. |
| 9247 | |
| 9248 | The @code{return} command does not resume execution; it leaves the |
| 9249 | program stopped in the state that would exist if the function had just |
| 9250 | returned. In contrast, the @code{finish} command (@pxref{Continuing |
| 9251 | and Stepping, ,Continuing and stepping}) resumes execution until the |
| 9252 | selected stack frame returns naturally. |
| 9253 | |
| 9254 | @node Calling |
| 9255 | @section Calling program functions |
| 9256 | |
| 9257 | @cindex calling functions |
| 9258 | @kindex call |
| 9259 | @table @code |
| 9260 | @item call @var{expr} |
| 9261 | Evaluate the expression @var{expr} without displaying @code{void} |
| 9262 | returned values. |
| 9263 | @end table |
| 9264 | |
| 9265 | You can use this variant of the @code{print} command if you want to |
| 9266 | execute a function from your program, but without cluttering the output |
| 9267 | with @code{void} returned values. If the result is not void, it |
| 9268 | is printed and saved in the value history. |
| 9269 | |
| 9270 | @node Patching |
| 9271 | @section Patching programs |
| 9272 | |
| 9273 | @cindex patching binaries |
| 9274 | @cindex writing into executables |
| 9275 | @cindex writing into corefiles |
| 9276 | |
| 9277 | By default, @value{GDBN} opens the file containing your program's |
| 9278 | executable code (or the corefile) read-only. This prevents accidental |
| 9279 | alterations to machine code; but it also prevents you from intentionally |
| 9280 | patching your program's binary. |
| 9281 | |
| 9282 | If you'd like to be able to patch the binary, you can specify that |
| 9283 | explicitly with the @code{set write} command. For example, you might |
| 9284 | want to turn on internal debugging flags, or even to make emergency |
| 9285 | repairs. |
| 9286 | |
| 9287 | @table @code |
| 9288 | @kindex set write |
| 9289 | @item set write on |
| 9290 | @itemx set write off |
| 9291 | If you specify @samp{set write on}, @value{GDBN} opens executable and |
| 9292 | core files for both reading and writing; if you specify @samp{set write |
| 9293 | off} (the default), @value{GDBN} opens them read-only. |
| 9294 | |
| 9295 | If you have already loaded a file, you must load it again (using the |
| 9296 | @code{exec-file} or @code{core-file} command) after changing @code{set |
| 9297 | write}, for your new setting to take effect. |
| 9298 | |
| 9299 | @item show write |
| 9300 | @kindex show write |
| 9301 | Display whether executable files and core files are opened for writing |
| 9302 | as well as reading. |
| 9303 | @end table |
| 9304 | |
| 9305 | @node GDB Files |
| 9306 | @chapter @value{GDBN} Files |
| 9307 | |
| 9308 | @value{GDBN} needs to know the file name of the program to be debugged, |
| 9309 | both in order to read its symbol table and in order to start your |
| 9310 | program. To debug a core dump of a previous run, you must also tell |
| 9311 | @value{GDBN} the name of the core dump file. |
| 9312 | |
| 9313 | @menu |
| 9314 | * Files:: Commands to specify files |
| 9315 | * Symbol Errors:: Errors reading symbol files |
| 9316 | @end menu |
| 9317 | |
| 9318 | @node Files |
| 9319 | @section Commands to specify files |
| 9320 | |
| 9321 | @cindex symbol table |
| 9322 | @cindex core dump file |
| 9323 | |
| 9324 | You may want to specify executable and core dump file names. The usual |
| 9325 | way to do this is at start-up time, using the arguments to |
| 9326 | @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and |
| 9327 | Out of @value{GDBN}}). |
| 9328 | |
| 9329 | Occasionally it is necessary to change to a different file during a |
| 9330 | @value{GDBN} session. Or you may run @value{GDBN} and forget to specify |
| 9331 | a file you want to use. In these situations the @value{GDBN} commands |
| 9332 | to specify new files are useful. |
| 9333 | |
| 9334 | @table @code |
| 9335 | @cindex executable file |
| 9336 | @kindex file |
| 9337 | @item file @var{filename} |
| 9338 | Use @var{filename} as the program to be debugged. It is read for its |
| 9339 | symbols and for the contents of pure memory. It is also the program |
| 9340 | executed when you use the @code{run} command. If you do not specify a |
| 9341 | directory and the file is not found in the @value{GDBN} working directory, |
| 9342 | @value{GDBN} uses the environment variable @code{PATH} as a list of |
| 9343 | directories to search, just as the shell does when looking for a program |
| 9344 | to run. You can change the value of this variable, for both @value{GDBN} |
| 9345 | and your program, using the @code{path} command. |
| 9346 | |
| 9347 | On systems with memory-mapped files, an auxiliary file named |
| 9348 | @file{@var{filename}.syms} may hold symbol table information for |
| 9349 | @var{filename}. If so, @value{GDBN} maps in the symbol table from |
| 9350 | @file{@var{filename}.syms}, starting up more quickly. See the |
| 9351 | descriptions of the file options @samp{-mapped} and @samp{-readnow} |
| 9352 | (available on the command line, and with the commands @code{file}, |
| 9353 | @code{symbol-file}, or @code{add-symbol-file}, described below), |
| 9354 | for more information. |
| 9355 | |
| 9356 | @item file |
| 9357 | @code{file} with no argument makes @value{GDBN} discard any information it |
| 9358 | has on both executable file and the symbol table. |
| 9359 | |
| 9360 | @kindex exec-file |
| 9361 | @item exec-file @r{[} @var{filename} @r{]} |
| 9362 | Specify that the program to be run (but not the symbol table) is found |
| 9363 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} |
| 9364 | if necessary to locate your program. Omitting @var{filename} means to |
| 9365 | discard information on the executable file. |
| 9366 | |
| 9367 | @kindex symbol-file |
| 9368 | @item symbol-file @r{[} @var{filename} @r{]} |
| 9369 | Read symbol table information from file @var{filename}. @code{PATH} is |
| 9370 | searched when necessary. Use the @code{file} command to get both symbol |
| 9371 | table and program to run from the same file. |
| 9372 | |
| 9373 | @code{symbol-file} with no argument clears out @value{GDBN} information on your |
| 9374 | program's symbol table. |
| 9375 | |
| 9376 | The @code{symbol-file} command causes @value{GDBN} to forget the contents |
| 9377 | of its convenience variables, the value history, and all breakpoints and |
| 9378 | auto-display expressions. This is because they may contain pointers to |
| 9379 | the internal data recording symbols and data types, which are part of |
| 9380 | the old symbol table data being discarded inside @value{GDBN}. |
| 9381 | |
| 9382 | @code{symbol-file} does not repeat if you press @key{RET} again after |
| 9383 | executing it once. |
| 9384 | |
| 9385 | When @value{GDBN} is configured for a particular environment, it |
| 9386 | understands debugging information in whatever format is the standard |
| 9387 | generated for that environment; you may use either a @sc{gnu} compiler, or |
| 9388 | other compilers that adhere to the local conventions. |
| 9389 | Best results are usually obtained from @sc{gnu} compilers; for example, |
| 9390 | using @code{@value{GCC}} you can generate debugging information for |
| 9391 | optimized code. |
| 9392 | |
| 9393 | For most kinds of object files, with the exception of old SVR3 systems |
| 9394 | using COFF, the @code{symbol-file} command does not normally read the |
| 9395 | symbol table in full right away. Instead, it scans the symbol table |
| 9396 | quickly to find which source files and which symbols are present. The |
| 9397 | details are read later, one source file at a time, as they are needed. |
| 9398 | |
| 9399 | The purpose of this two-stage reading strategy is to make @value{GDBN} |
| 9400 | start up faster. For the most part, it is invisible except for |
| 9401 | occasional pauses while the symbol table details for a particular source |
| 9402 | file are being read. (The @code{set verbose} command can turn these |
| 9403 | pauses into messages if desired. @xref{Messages/Warnings, ,Optional |
| 9404 | warnings and messages}.) |
| 9405 | |
| 9406 | We have not implemented the two-stage strategy for COFF yet. When the |
| 9407 | symbol table is stored in COFF format, @code{symbol-file} reads the |
| 9408 | symbol table data in full right away. Note that ``stabs-in-COFF'' |
| 9409 | still does the two-stage strategy, since the debug info is actually |
| 9410 | in stabs format. |
| 9411 | |
| 9412 | @kindex readnow |
| 9413 | @cindex reading symbols immediately |
| 9414 | @cindex symbols, reading immediately |
| 9415 | @kindex mapped |
| 9416 | @cindex memory-mapped symbol file |
| 9417 | @cindex saving symbol table |
| 9418 | @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} |
| 9419 | @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} |
| 9420 | You can override the @value{GDBN} two-stage strategy for reading symbol |
| 9421 | tables by using the @samp{-readnow} option with any of the commands that |
| 9422 | load symbol table information, if you want to be sure @value{GDBN} has the |
| 9423 | entire symbol table available. |
| 9424 | |
| 9425 | If memory-mapped files are available on your system through the |
| 9426 | @code{mmap} system call, you can use another option, @samp{-mapped}, to |
| 9427 | cause @value{GDBN} to write the symbols for your program into a reusable |
| 9428 | file. Future @value{GDBN} debugging sessions map in symbol information |
| 9429 | from this auxiliary symbol file (if the program has not changed), rather |
| 9430 | than spending time reading the symbol table from the executable |
| 9431 | program. Using the @samp{-mapped} option has the same effect as |
| 9432 | starting @value{GDBN} with the @samp{-mapped} command-line option. |
| 9433 | |
| 9434 | You can use both options together, to make sure the auxiliary symbol |
| 9435 | file has all the symbol information for your program. |
| 9436 | |
| 9437 | The auxiliary symbol file for a program called @var{myprog} is called |
| 9438 | @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer |
| 9439 | than the corresponding executable), @value{GDBN} always attempts to use |
| 9440 | it when you debug @var{myprog}; no special options or commands are |
| 9441 | needed. |
| 9442 | |
| 9443 | The @file{.syms} file is specific to the host machine where you run |
| 9444 | @value{GDBN}. It holds an exact image of the internal @value{GDBN} |
| 9445 | symbol table. It cannot be shared across multiple host platforms. |
| 9446 | |
| 9447 | @c FIXME: for now no mention of directories, since this seems to be in |
| 9448 | @c flux. 13mar1992 status is that in theory GDB would look either in |
| 9449 | @c current dir or in same dir as myprog; but issues like competing |
| 9450 | @c GDB's, or clutter in system dirs, mean that in practice right now |
| 9451 | @c only current dir is used. FFish says maybe a special GDB hierarchy |
| 9452 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol |
| 9453 | @c files. |
| 9454 | |
| 9455 | @kindex core |
| 9456 | @kindex core-file |
| 9457 | @item core-file @r{[} @var{filename} @r{]} |
| 9458 | Specify the whereabouts of a core dump file to be used as the ``contents |
| 9459 | of memory''. Traditionally, core files contain only some parts of the |
| 9460 | address space of the process that generated them; @value{GDBN} can access the |
| 9461 | executable file itself for other parts. |
| 9462 | |
| 9463 | @code{core-file} with no argument specifies that no core file is |
| 9464 | to be used. |
| 9465 | |
| 9466 | Note that the core file is ignored when your program is actually running |
| 9467 | under @value{GDBN}. So, if you have been running your program and you |
| 9468 | wish to debug a core file instead, you must kill the subprocess in which |
| 9469 | the program is running. To do this, use the @code{kill} command |
| 9470 | (@pxref{Kill Process, ,Killing the child process}). |
| 9471 | |
| 9472 | @kindex add-symbol-file |
| 9473 | @cindex dynamic linking |
| 9474 | @item add-symbol-file @var{filename} @var{address} |
| 9475 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} |
| 9476 | @itemx add-symbol-file @var{filename} @r{-s}@var{section} @var{address} @dots{} |
| 9477 | The @code{add-symbol-file} command reads additional symbol table |
| 9478 | information from the file @var{filename}. You would use this command |
| 9479 | when @var{filename} has been dynamically loaded (by some other means) |
| 9480 | into the program that is running. @var{address} should be the memory |
| 9481 | address at which the file has been loaded; @value{GDBN} cannot figure |
| 9482 | this out for itself. You can additionally specify an arbitrary number |
| 9483 | of @samp{@r{-s}@var{section} @var{address}} pairs, to give an explicit |
| 9484 | section name and base address for that section. You can specify any |
| 9485 | @var{address} as an expression. |
| 9486 | |
| 9487 | The symbol table of the file @var{filename} is added to the symbol table |
| 9488 | originally read with the @code{symbol-file} command. You can use the |
| 9489 | @code{add-symbol-file} command any number of times; the new symbol data |
| 9490 | thus read keeps adding to the old. To discard all old symbol data |
| 9491 | instead, use the @code{symbol-file} command without any arguments. |
| 9492 | |
| 9493 | @cindex relocatable object files, reading symbols from |
| 9494 | @cindex object files, relocatable, reading symbols from |
| 9495 | @cindex reading symbols from relocatable object files |
| 9496 | @cindex symbols, reading from relocatable object files |
| 9497 | @cindex @file{.o} files, reading symbols from |
| 9498 | Although @var{filename} is typically a shared library file, an |
| 9499 | executable file, or some other object file which has been fully |
| 9500 | relocated for loading into a process, you can also load symbolic |
| 9501 | information from relocatable @file{.o} files, as long as: |
| 9502 | |
| 9503 | @itemize @bullet |
| 9504 | @item |
| 9505 | the file's symbolic information refers only to linker symbols defined in |
| 9506 | that file, not to symbols defined by other object files, |
| 9507 | @item |
| 9508 | every section the file's symbolic information refers to has actually |
| 9509 | been loaded into the inferior, as it appears in the file, and |
| 9510 | @item |
| 9511 | you can determine the address at which every section was loaded, and |
| 9512 | provide these to the @code{add-symbol-file} command. |
| 9513 | @end itemize |
| 9514 | |
| 9515 | @noindent |
| 9516 | Some embedded operating systems, like Sun Chorus and VxWorks, can load |
| 9517 | relocatable files into an already running program; such systems |
| 9518 | typically make the requirements above easy to meet. However, it's |
| 9519 | important to recognize that many native systems use complex link |
| 9520 | procedures (@code{.linkonce} section factoring and C++ constructor table |
| 9521 | assembly, for example) that make the requirements difficult to meet. In |
| 9522 | general, one cannot assume that using @code{add-symbol-file} to read a |
| 9523 | relocatable object file's symbolic information will have the same effect |
| 9524 | as linking the relocatable object file into the program in the normal |
| 9525 | way. |
| 9526 | |
| 9527 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. |
| 9528 | |
| 9529 | You can use the @samp{-mapped} and @samp{-readnow} options just as with |
| 9530 | the @code{symbol-file} command, to change how @value{GDBN} manages the symbol |
| 9531 | table information for @var{filename}. |
| 9532 | |
| 9533 | @kindex add-shared-symbol-file |
| 9534 | @item add-shared-symbol-file |
| 9535 | The @code{add-shared-symbol-file} command can be used only under Harris' CXUX |
| 9536 | operating system for the Motorola 88k. @value{GDBN} automatically looks for |
| 9537 | shared libraries, however if @value{GDBN} does not find yours, you can run |
| 9538 | @code{add-shared-symbol-file}. It takes no arguments. |
| 9539 | |
| 9540 | @kindex section |
| 9541 | @item section |
| 9542 | The @code{section} command changes the base address of section SECTION of |
| 9543 | the exec file to ADDR. This can be used if the exec file does not contain |
| 9544 | section addresses, (such as in the a.out format), or when the addresses |
| 9545 | specified in the file itself are wrong. Each section must be changed |
| 9546 | separately. The @code{info files} command, described below, lists all |
| 9547 | the sections and their addresses. |
| 9548 | |
| 9549 | @kindex info files |
| 9550 | @kindex info target |
| 9551 | @item info files |
| 9552 | @itemx info target |
| 9553 | @code{info files} and @code{info target} are synonymous; both print the |
| 9554 | current target (@pxref{Targets, ,Specifying a Debugging Target}), |
| 9555 | including the names of the executable and core dump files currently in |
| 9556 | use by @value{GDBN}, and the files from which symbols were loaded. The |
| 9557 | command @code{help target} lists all possible targets rather than |
| 9558 | current ones. |
| 9559 | |
| 9560 | @kindex maint info sections |
| 9561 | @item maint info sections |
| 9562 | Another command that can give you extra information about program sections |
| 9563 | is @code{maint info sections}. In addition to the section information |
| 9564 | displayed by @code{info files}, this command displays the flags and file |
| 9565 | offset of each section in the executable and core dump files. In addition, |
| 9566 | @code{maint info sections} provides the following command options (which |
| 9567 | may be arbitrarily combined): |
| 9568 | |
| 9569 | @table @code |
| 9570 | @item ALLOBJ |
| 9571 | Display sections for all loaded object files, including shared libraries. |
| 9572 | @item @var{sections} |
| 9573 | Display info only for named @var{sections}. |
| 9574 | @item @var{section-flags} |
| 9575 | Display info only for sections for which @var{section-flags} are true. |
| 9576 | The section flags that @value{GDBN} currently knows about are: |
| 9577 | @table @code |
| 9578 | @item ALLOC |
| 9579 | Section will have space allocated in the process when loaded. |
| 9580 | Set for all sections except those containing debug information. |
| 9581 | @item LOAD |
| 9582 | Section will be loaded from the file into the child process memory. |
| 9583 | Set for pre-initialized code and data, clear for @code{.bss} sections. |
| 9584 | @item RELOC |
| 9585 | Section needs to be relocated before loading. |
| 9586 | @item READONLY |
| 9587 | Section cannot be modified by the child process. |
| 9588 | @item CODE |
| 9589 | Section contains executable code only. |
| 9590 | @item DATA |
| 9591 | Section contains data only (no executable code). |
| 9592 | @item ROM |
| 9593 | Section will reside in ROM. |
| 9594 | @item CONSTRUCTOR |
| 9595 | Section contains data for constructor/destructor lists. |
| 9596 | @item HAS_CONTENTS |
| 9597 | Section is not empty. |
| 9598 | @item NEVER_LOAD |
| 9599 | An instruction to the linker to not output the section. |
| 9600 | @item COFF_SHARED_LIBRARY |
| 9601 | A notification to the linker that the section contains |
| 9602 | COFF shared library information. |
| 9603 | @item IS_COMMON |
| 9604 | Section contains common symbols. |
| 9605 | @end table |
| 9606 | @end table |
| 9607 | @kindex set trust-readonly-sections |
| 9608 | @item set trust-readonly-sections on |
| 9609 | Tell @value{GDBN} that readonly sections in your object file |
| 9610 | really are read-only (i.e.@: that their contents will not change). |
| 9611 | In that case, @value{GDBN} can fetch values from these sections |
| 9612 | out of the object file, rather than from the target program. |
| 9613 | For some targets (notably embedded ones), this can be a significant |
| 9614 | enhancement to debugging performance. |
| 9615 | |
| 9616 | The default is off. |
| 9617 | |
| 9618 | @item set trust-readonly-sections off |
| 9619 | Tell @value{GDBN} not to trust readonly sections. This means that |
| 9620 | the contents of the section might change while the program is running, |
| 9621 | and must therefore be fetched from the target when needed. |
| 9622 | @end table |
| 9623 | |
| 9624 | All file-specifying commands allow both absolute and relative file names |
| 9625 | as arguments. @value{GDBN} always converts the file name to an absolute file |
| 9626 | name and remembers it that way. |
| 9627 | |
| 9628 | @cindex shared libraries |
| 9629 | @value{GDBN} supports HP-UX, SunOS, SVr4, Irix 5, and IBM RS/6000 shared |
| 9630 | libraries. |
| 9631 | |
| 9632 | @value{GDBN} automatically loads symbol definitions from shared libraries |
| 9633 | when you use the @code{run} command, or when you examine a core file. |
| 9634 | (Before you issue the @code{run} command, @value{GDBN} does not understand |
| 9635 | references to a function in a shared library, however---unless you are |
| 9636 | debugging a core file). |
| 9637 | |
| 9638 | On HP-UX, if the program loads a library explicitly, @value{GDBN} |
| 9639 | automatically loads the symbols at the time of the @code{shl_load} call. |
| 9640 | |
| 9641 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
| 9642 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared |
| 9643 | @c FIXME...lib; check this from time to time when updating manual |
| 9644 | |
| 9645 | There are times, however, when you may wish to not automatically load |
| 9646 | symbol definitions from shared libraries, such as when they are |
| 9647 | particularly large or there are many of them. |
| 9648 | |
| 9649 | To control the automatic loading of shared library symbols, use the |
| 9650 | commands: |
| 9651 | |
| 9652 | @table @code |
| 9653 | @kindex set auto-solib-add |
| 9654 | @item set auto-solib-add @var{mode} |
| 9655 | If @var{mode} is @code{on}, symbols from all shared object libraries |
| 9656 | will be loaded automatically when the inferior begins execution, you |
| 9657 | attach to an independently started inferior, or when the dynamic linker |
| 9658 | informs @value{GDBN} that a new library has been loaded. If @var{mode} |
| 9659 | is @code{off}, symbols must be loaded manually, using the |
| 9660 | @code{sharedlibrary} command. The default value is @code{on}. |
| 9661 | |
| 9662 | @kindex show auto-solib-add |
| 9663 | @item show auto-solib-add |
| 9664 | Display the current autoloading mode. |
| 9665 | @end table |
| 9666 | |
| 9667 | To explicitly load shared library symbols, use the @code{sharedlibrary} |
| 9668 | command: |
| 9669 | |
| 9670 | @table @code |
| 9671 | @kindex info sharedlibrary |
| 9672 | @kindex info share |
| 9673 | @item info share |
| 9674 | @itemx info sharedlibrary |
| 9675 | Print the names of the shared libraries which are currently loaded. |
| 9676 | |
| 9677 | @kindex sharedlibrary |
| 9678 | @kindex share |
| 9679 | @item sharedlibrary @var{regex} |
| 9680 | @itemx share @var{regex} |
| 9681 | Load shared object library symbols for files matching a |
| 9682 | Unix regular expression. |
| 9683 | As with files loaded automatically, it only loads shared libraries |
| 9684 | required by your program for a core file or after typing @code{run}. If |
| 9685 | @var{regex} is omitted all shared libraries required by your program are |
| 9686 | loaded. |
| 9687 | @end table |
| 9688 | |
| 9689 | On some systems, such as HP-UX systems, @value{GDBN} supports |
| 9690 | autoloading shared library symbols until a limiting threshold size is |
| 9691 | reached. This provides the benefit of allowing autoloading to remain on |
| 9692 | by default, but avoids autoloading excessively large shared libraries, |
| 9693 | up to a threshold that is initially set, but which you can modify if you |
| 9694 | wish. |
| 9695 | |
| 9696 | Beyond that threshold, symbols from shared libraries must be explicitly |
| 9697 | loaded. To load these symbols, use the command @code{sharedlibrary |
| 9698 | @var{filename}}. The base address of the shared library is determined |
| 9699 | automatically by @value{GDBN} and need not be specified. |
| 9700 | |
| 9701 | To display or set the threshold, use the commands: |
| 9702 | |
| 9703 | @table @code |
| 9704 | @kindex set auto-solib-limit |
| 9705 | @item set auto-solib-limit @var{threshold} |
| 9706 | Set the autoloading size threshold, in an integral number of megabytes. |
| 9707 | If @var{threshold} is nonzero and shared library autoloading is enabled, |
| 9708 | symbols from all shared object libraries will be loaded until the total |
| 9709 | size of the loaded shared library symbols exceeds this threshold. |
| 9710 | Otherwise, symbols must be loaded manually, using the |
| 9711 | @code{sharedlibrary} command. The default threshold is 100 (i.e.@: 100 |
| 9712 | Mb). |
| 9713 | |
| 9714 | @kindex show auto-solib-limit |
| 9715 | @item show auto-solib-limit |
| 9716 | Display the current autoloading size threshold, in megabytes. |
| 9717 | @end table |
| 9718 | |
| 9719 | @node Symbol Errors |
| 9720 | @section Errors reading symbol files |
| 9721 | |
| 9722 | While reading a symbol file, @value{GDBN} occasionally encounters problems, |
| 9723 | such as symbol types it does not recognize, or known bugs in compiler |
| 9724 | output. By default, @value{GDBN} does not notify you of such problems, since |
| 9725 | they are relatively common and primarily of interest to people |
| 9726 | debugging compilers. If you are interested in seeing information |
| 9727 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print |
| 9728 | only one message about each such type of problem, no matter how many |
| 9729 | times the problem occurs; or you can ask @value{GDBN} to print more messages, |
| 9730 | to see how many times the problems occur, with the @code{set |
| 9731 | complaints} command (@pxref{Messages/Warnings, ,Optional warnings and |
| 9732 | messages}). |
| 9733 | |
| 9734 | The messages currently printed, and their meanings, include: |
| 9735 | |
| 9736 | @table @code |
| 9737 | @item inner block not inside outer block in @var{symbol} |
| 9738 | |
| 9739 | The symbol information shows where symbol scopes begin and end |
| 9740 | (such as at the start of a function or a block of statements). This |
| 9741 | error indicates that an inner scope block is not fully contained |
| 9742 | in its outer scope blocks. |
| 9743 | |
| 9744 | @value{GDBN} circumvents the problem by treating the inner block as if it had |
| 9745 | the same scope as the outer block. In the error message, @var{symbol} |
| 9746 | may be shown as ``@code{(don't know)}'' if the outer block is not a |
| 9747 | function. |
| 9748 | |
| 9749 | @item block at @var{address} out of order |
| 9750 | |
| 9751 | The symbol information for symbol scope blocks should occur in |
| 9752 | order of increasing addresses. This error indicates that it does not |
| 9753 | do so. |
| 9754 | |
| 9755 | @value{GDBN} does not circumvent this problem, and has trouble |
| 9756 | locating symbols in the source file whose symbols it is reading. (You |
| 9757 | can often determine what source file is affected by specifying |
| 9758 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and |
| 9759 | messages}.) |
| 9760 | |
| 9761 | @item bad block start address patched |
| 9762 | |
| 9763 | The symbol information for a symbol scope block has a start address |
| 9764 | smaller than the address of the preceding source line. This is known |
| 9765 | to occur in the SunOS 4.1.1 (and earlier) C compiler. |
| 9766 | |
| 9767 | @value{GDBN} circumvents the problem by treating the symbol scope block as |
| 9768 | starting on the previous source line. |
| 9769 | |
| 9770 | @item bad string table offset in symbol @var{n} |
| 9771 | |
| 9772 | @cindex foo |
| 9773 | Symbol number @var{n} contains a pointer into the string table which is |
| 9774 | larger than the size of the string table. |
| 9775 | |
| 9776 | @value{GDBN} circumvents the problem by considering the symbol to have the |
| 9777 | name @code{foo}, which may cause other problems if many symbols end up |
| 9778 | with this name. |
| 9779 | |
| 9780 | @item unknown symbol type @code{0x@var{nn}} |
| 9781 | |
| 9782 | The symbol information contains new data types that @value{GDBN} does |
| 9783 | not yet know how to read. @code{0x@var{nn}} is the symbol type of the |
| 9784 | uncomprehended information, in hexadecimal. |
| 9785 | |
| 9786 | @value{GDBN} circumvents the error by ignoring this symbol information. |
| 9787 | This usually allows you to debug your program, though certain symbols |
| 9788 | are not accessible. If you encounter such a problem and feel like |
| 9789 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint |
| 9790 | on @code{complain}, then go up to the function @code{read_dbx_symtab} |
| 9791 | and examine @code{*bufp} to see the symbol. |
| 9792 | |
| 9793 | @item stub type has NULL name |
| 9794 | |
| 9795 | @value{GDBN} could not find the full definition for a struct or class. |
| 9796 | |
| 9797 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
| 9798 | The symbol information for a C@t{++} member function is missing some |
| 9799 | information that recent versions of the compiler should have output for |
| 9800 | it. |
| 9801 | |
| 9802 | @item info mismatch between compiler and debugger |
| 9803 | |
| 9804 | @value{GDBN} could not parse a type specification output by the compiler. |
| 9805 | |
| 9806 | @end table |
| 9807 | |
| 9808 | @node Targets |
| 9809 | @chapter Specifying a Debugging Target |
| 9810 | |
| 9811 | @cindex debugging target |
| 9812 | @kindex target |
| 9813 | |
| 9814 | A @dfn{target} is the execution environment occupied by your program. |
| 9815 | |
| 9816 | Often, @value{GDBN} runs in the same host environment as your program; |
| 9817 | in that case, the debugging target is specified as a side effect when |
| 9818 | you use the @code{file} or @code{core} commands. When you need more |
| 9819 | flexibility---for example, running @value{GDBN} on a physically separate |
| 9820 | host, or controlling a standalone system over a serial port or a |
| 9821 | realtime system over a TCP/IP connection---you can use the @code{target} |
| 9822 | command to specify one of the target types configured for @value{GDBN} |
| 9823 | (@pxref{Target Commands, ,Commands for managing targets}). |
| 9824 | |
| 9825 | @menu |
| 9826 | * Active Targets:: Active targets |
| 9827 | * Target Commands:: Commands for managing targets |
| 9828 | * Byte Order:: Choosing target byte order |
| 9829 | * Remote:: Remote debugging |
| 9830 | * KOD:: Kernel Object Display |
| 9831 | |
| 9832 | @end menu |
| 9833 | |
| 9834 | @node Active Targets |
| 9835 | @section Active targets |
| 9836 | |
| 9837 | @cindex stacking targets |
| 9838 | @cindex active targets |
| 9839 | @cindex multiple targets |
| 9840 | |
| 9841 | There are three classes of targets: processes, core files, and |
| 9842 | executable files. @value{GDBN} can work concurrently on up to three |
| 9843 | active targets, one in each class. This allows you to (for example) |
| 9844 | start a process and inspect its activity without abandoning your work on |
| 9845 | a core file. |
| 9846 | |
| 9847 | For example, if you execute @samp{gdb a.out}, then the executable file |
| 9848 | @code{a.out} is the only active target. If you designate a core file as |
| 9849 | well---presumably from a prior run that crashed and coredumped---then |
| 9850 | @value{GDBN} has two active targets and uses them in tandem, looking |
| 9851 | first in the corefile target, then in the executable file, to satisfy |
| 9852 | requests for memory addresses. (Typically, these two classes of target |
| 9853 | are complementary, since core files contain only a program's |
| 9854 | read-write memory---variables and so on---plus machine status, while |
| 9855 | executable files contain only the program text and initialized data.) |
| 9856 | |
| 9857 | When you type @code{run}, your executable file becomes an active process |
| 9858 | target as well. When a process target is active, all @value{GDBN} |
| 9859 | commands requesting memory addresses refer to that target; addresses in |
| 9860 | an active core file or executable file target are obscured while the |
| 9861 | process target is active. |
| 9862 | |
| 9863 | Use the @code{core-file} and @code{exec-file} commands to select a new |
| 9864 | core file or executable target (@pxref{Files, ,Commands to specify |
| 9865 | files}). To specify as a target a process that is already running, use |
| 9866 | the @code{attach} command (@pxref{Attach, ,Debugging an already-running |
| 9867 | process}). |
| 9868 | |
| 9869 | @node Target Commands |
| 9870 | @section Commands for managing targets |
| 9871 | |
| 9872 | @table @code |
| 9873 | @item target @var{type} @var{parameters} |
| 9874 | Connects the @value{GDBN} host environment to a target machine or |
| 9875 | process. A target is typically a protocol for talking to debugging |
| 9876 | facilities. You use the argument @var{type} to specify the type or |
| 9877 | protocol of the target machine. |
| 9878 | |
| 9879 | Further @var{parameters} are interpreted by the target protocol, but |
| 9880 | typically include things like device names or host names to connect |
| 9881 | with, process numbers, and baud rates. |
| 9882 | |
| 9883 | The @code{target} command does not repeat if you press @key{RET} again |
| 9884 | after executing the command. |
| 9885 | |
| 9886 | @kindex help target |
| 9887 | @item help target |
| 9888 | Displays the names of all targets available. To display targets |
| 9889 | currently selected, use either @code{info target} or @code{info files} |
| 9890 | (@pxref{Files, ,Commands to specify files}). |
| 9891 | |
| 9892 | @item help target @var{name} |
| 9893 | Describe a particular target, including any parameters necessary to |
| 9894 | select it. |
| 9895 | |
| 9896 | @kindex set gnutarget |
| 9897 | @item set gnutarget @var{args} |
| 9898 | @value{GDBN} uses its own library BFD to read your files. @value{GDBN} |
| 9899 | knows whether it is reading an @dfn{executable}, |
| 9900 | a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format |
| 9901 | with the @code{set gnutarget} command. Unlike most @code{target} commands, |
| 9902 | with @code{gnutarget} the @code{target} refers to a program, not a machine. |
| 9903 | |
| 9904 | @quotation |
| 9905 | @emph{Warning:} To specify a file format with @code{set gnutarget}, |
| 9906 | you must know the actual BFD name. |
| 9907 | @end quotation |
| 9908 | |
| 9909 | @noindent |
| 9910 | @xref{Files, , Commands to specify files}. |
| 9911 | |
| 9912 | @kindex show gnutarget |
| 9913 | @item show gnutarget |
| 9914 | Use the @code{show gnutarget} command to display what file format |
| 9915 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, |
| 9916 | @value{GDBN} will determine the file format for each file automatically, |
| 9917 | and @code{show gnutarget} displays @samp{The current BDF target is "auto"}. |
| 9918 | @end table |
| 9919 | |
| 9920 | Here are some common targets (available, or not, depending on the GDB |
| 9921 | configuration): |
| 9922 | |
| 9923 | @table @code |
| 9924 | @kindex target exec |
| 9925 | @item target exec @var{program} |
| 9926 | An executable file. @samp{target exec @var{program}} is the same as |
| 9927 | @samp{exec-file @var{program}}. |
| 9928 | |
| 9929 | @kindex target core |
| 9930 | @item target core @var{filename} |
| 9931 | A core dump file. @samp{target core @var{filename}} is the same as |
| 9932 | @samp{core-file @var{filename}}. |
| 9933 | |
| 9934 | @kindex target remote |
| 9935 | @item target remote @var{dev} |
| 9936 | Remote serial target in GDB-specific protocol. The argument @var{dev} |
| 9937 | specifies what serial device to use for the connection (e.g. |
| 9938 | @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote} |
| 9939 | supports the @code{load} command. This is only useful if you have |
| 9940 | some other way of getting the stub to the target system, and you can put |
| 9941 | it somewhere in memory where it won't get clobbered by the download. |
| 9942 | |
| 9943 | @kindex target sim |
| 9944 | @item target sim |
| 9945 | Builtin CPU simulator. @value{GDBN} includes simulators for most architectures. |
| 9946 | In general, |
| 9947 | @smallexample |
| 9948 | target sim |
| 9949 | load |
| 9950 | run |
| 9951 | @end smallexample |
| 9952 | @noindent |
| 9953 | works; however, you cannot assume that a specific memory map, device |
| 9954 | drivers, or even basic I/O is available, although some simulators do |
| 9955 | provide these. For info about any processor-specific simulator details, |
| 9956 | see the appropriate section in @ref{Embedded Processors, ,Embedded |
| 9957 | Processors}. |
| 9958 | |
| 9959 | @end table |
| 9960 | |
| 9961 | Some configurations may include these targets as well: |
| 9962 | |
| 9963 | @table @code |
| 9964 | |
| 9965 | @kindex target nrom |
| 9966 | @item target nrom @var{dev} |
| 9967 | NetROM ROM emulator. This target only supports downloading. |
| 9968 | |
| 9969 | @end table |
| 9970 | |
| 9971 | Different targets are available on different configurations of @value{GDBN}; |
| 9972 | your configuration may have more or fewer targets. |
| 9973 | |
| 9974 | Many remote targets require you to download the executable's code |
| 9975 | once you've successfully established a connection. |
| 9976 | |
| 9977 | @table @code |
| 9978 | |
| 9979 | @kindex load @var{filename} |
| 9980 | @item load @var{filename} |
| 9981 | Depending on what remote debugging facilities are configured into |
| 9982 | @value{GDBN}, the @code{load} command may be available. Where it exists, it |
| 9983 | is meant to make @var{filename} (an executable) available for debugging |
| 9984 | on the remote system---by downloading, or dynamic linking, for example. |
| 9985 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like |
| 9986 | the @code{add-symbol-file} command. |
| 9987 | |
| 9988 | If your @value{GDBN} does not have a @code{load} command, attempting to |
| 9989 | execute it gets the error message ``@code{You can't do that when your |
| 9990 | target is @dots{}}'' |
| 9991 | |
| 9992 | The file is loaded at whatever address is specified in the executable. |
| 9993 | For some object file formats, you can specify the load address when you |
| 9994 | link the program; for other formats, like a.out, the object file format |
| 9995 | specifies a fixed address. |
| 9996 | @c FIXME! This would be a good place for an xref to the GNU linker doc. |
| 9997 | |
| 9998 | @code{load} does not repeat if you press @key{RET} again after using it. |
| 9999 | @end table |
| 10000 | |
| 10001 | @node Byte Order |
| 10002 | @section Choosing target byte order |
| 10003 | |
| 10004 | @cindex choosing target byte order |
| 10005 | @cindex target byte order |
| 10006 | |
| 10007 | Some types of processors, such as the MIPS, PowerPC, and Hitachi SH, |
| 10008 | offer the ability to run either big-endian or little-endian byte |
| 10009 | orders. Usually the executable or symbol will include a bit to |
| 10010 | designate the endian-ness, and you will not need to worry about |
| 10011 | which to use. However, you may still find it useful to adjust |
| 10012 | @value{GDBN}'s idea of processor endian-ness manually. |
| 10013 | |
| 10014 | @table @code |
| 10015 | @kindex set endian big |
| 10016 | @item set endian big |
| 10017 | Instruct @value{GDBN} to assume the target is big-endian. |
| 10018 | |
| 10019 | @kindex set endian little |
| 10020 | @item set endian little |
| 10021 | Instruct @value{GDBN} to assume the target is little-endian. |
| 10022 | |
| 10023 | @kindex set endian auto |
| 10024 | @item set endian auto |
| 10025 | Instruct @value{GDBN} to use the byte order associated with the |
| 10026 | executable. |
| 10027 | |
| 10028 | @item show endian |
| 10029 | Display @value{GDBN}'s current idea of the target byte order. |
| 10030 | |
| 10031 | @end table |
| 10032 | |
| 10033 | Note that these commands merely adjust interpretation of symbolic |
| 10034 | data on the host, and that they have absolutely no effect on the |
| 10035 | target system. |
| 10036 | |
| 10037 | @node Remote |
| 10038 | @section Remote debugging |
| 10039 | @cindex remote debugging |
| 10040 | |
| 10041 | If you are trying to debug a program running on a machine that cannot run |
| 10042 | @value{GDBN} in the usual way, it is often useful to use remote debugging. |
| 10043 | For example, you might use remote debugging on an operating system kernel, |
| 10044 | or on a small system which does not have a general purpose operating system |
| 10045 | powerful enough to run a full-featured debugger. |
| 10046 | |
| 10047 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces |
| 10048 | to make this work with particular debugging targets. In addition, |
| 10049 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, |
| 10050 | but not specific to any particular target system) which you can use if you |
| 10051 | write the remote stubs---the code that runs on the remote system to |
| 10052 | communicate with @value{GDBN}. |
| 10053 | |
| 10054 | Other remote targets may be available in your |
| 10055 | configuration of @value{GDBN}; use @code{help target} to list them. |
| 10056 | |
| 10057 | @node KOD |
| 10058 | @section Kernel Object Display |
| 10059 | |
| 10060 | @cindex kernel object display |
| 10061 | @cindex kernel object |
| 10062 | @cindex KOD |
| 10063 | |
| 10064 | Some targets support kernel object display. Using this facility, |
| 10065 | @value{GDBN} communicates specially with the underlying operating system |
| 10066 | and can display information about operating system-level objects such as |
| 10067 | mutexes and other synchronization objects. Exactly which objects can be |
| 10068 | displayed is determined on a per-OS basis. |
| 10069 | |
| 10070 | Use the @code{set os} command to set the operating system. This tells |
| 10071 | @value{GDBN} which kernel object display module to initialize: |
| 10072 | |
| 10073 | @smallexample |
| 10074 | (@value{GDBP}) set os cisco |
| 10075 | @end smallexample |
| 10076 | |
| 10077 | If @code{set os} succeeds, @value{GDBN} will display some information |
| 10078 | about the operating system, and will create a new @code{info} command |
| 10079 | which can be used to query the target. The @code{info} command is named |
| 10080 | after the operating system: |
| 10081 | |
| 10082 | @smallexample |
| 10083 | (@value{GDBP}) info cisco |
| 10084 | List of Cisco Kernel Objects |
| 10085 | Object Description |
| 10086 | any Any and all objects |
| 10087 | @end smallexample |
| 10088 | |
| 10089 | Further subcommands can be used to query about particular objects known |
| 10090 | by the kernel. |
| 10091 | |
| 10092 | There is currently no way to determine whether a given operating system |
| 10093 | is supported other than to try it. |
| 10094 | |
| 10095 | |
| 10096 | @node Remote Debugging |
| 10097 | @chapter Debugging remote programs |
| 10098 | |
| 10099 | @menu |
| 10100 | * Server:: Using the gdbserver program |
| 10101 | * NetWare:: Using the gdbserve.nlm program |
| 10102 | * remote stub:: Implementing a remote stub |
| 10103 | @end menu |
| 10104 | |
| 10105 | @node Server |
| 10106 | @section Using the @code{gdbserver} program |
| 10107 | |
| 10108 | @kindex gdbserver |
| 10109 | @cindex remote connection without stubs |
| 10110 | @code{gdbserver} is a control program for Unix-like systems, which |
| 10111 | allows you to connect your program with a remote @value{GDBN} via |
| 10112 | @code{target remote}---but without linking in the usual debugging stub. |
| 10113 | |
| 10114 | @code{gdbserver} is not a complete replacement for the debugging stubs, |
| 10115 | because it requires essentially the same operating-system facilities |
| 10116 | that @value{GDBN} itself does. In fact, a system that can run |
| 10117 | @code{gdbserver} to connect to a remote @value{GDBN} could also run |
| 10118 | @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, |
| 10119 | because it is a much smaller program than @value{GDBN} itself. It is |
| 10120 | also easier to port than all of @value{GDBN}, so you may be able to get |
| 10121 | started more quickly on a new system by using @code{gdbserver}. |
| 10122 | Finally, if you develop code for real-time systems, you may find that |
| 10123 | the tradeoffs involved in real-time operation make it more convenient to |
| 10124 | do as much development work as possible on another system, for example |
| 10125 | by cross-compiling. You can use @code{gdbserver} to make a similar |
| 10126 | choice for debugging. |
| 10127 | |
| 10128 | @value{GDBN} and @code{gdbserver} communicate via either a serial line |
| 10129 | or a TCP connection, using the standard @value{GDBN} remote serial |
| 10130 | protocol. |
| 10131 | |
| 10132 | @table @emph |
| 10133 | @item On the target machine, |
| 10134 | you need to have a copy of the program you want to debug. |
| 10135 | @code{gdbserver} does not need your program's symbol table, so you can |
| 10136 | strip the program if necessary to save space. @value{GDBN} on the host |
| 10137 | system does all the symbol handling. |
| 10138 | |
| 10139 | To use the server, you must tell it how to communicate with @value{GDBN}; |
| 10140 | the name of your program; and the arguments for your program. The usual |
| 10141 | syntax is: |
| 10142 | |
| 10143 | @smallexample |
| 10144 | target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] |
| 10145 | @end smallexample |
| 10146 | |
| 10147 | @var{comm} is either a device name (to use a serial line) or a TCP |
| 10148 | hostname and portnumber. For example, to debug Emacs with the argument |
| 10149 | @samp{foo.txt} and communicate with @value{GDBN} over the serial port |
| 10150 | @file{/dev/com1}: |
| 10151 | |
| 10152 | @smallexample |
| 10153 | target> gdbserver /dev/com1 emacs foo.txt |
| 10154 | @end smallexample |
| 10155 | |
| 10156 | @code{gdbserver} waits passively for the host @value{GDBN} to communicate |
| 10157 | with it. |
| 10158 | |
| 10159 | To use a TCP connection instead of a serial line: |
| 10160 | |
| 10161 | @smallexample |
| 10162 | target> gdbserver host:2345 emacs foo.txt |
| 10163 | @end smallexample |
| 10164 | |
| 10165 | The only difference from the previous example is the first argument, |
| 10166 | specifying that you are communicating with the host @value{GDBN} via |
| 10167 | TCP. The @samp{host:2345} argument means that @code{gdbserver} is to |
| 10168 | expect a TCP connection from machine @samp{host} to local TCP port 2345. |
| 10169 | (Currently, the @samp{host} part is ignored.) You can choose any number |
| 10170 | you want for the port number as long as it does not conflict with any |
| 10171 | TCP ports already in use on the target system (for example, @code{23} is |
| 10172 | reserved for @code{telnet}).@footnote{If you choose a port number that |
| 10173 | conflicts with another service, @code{gdbserver} prints an error message |
| 10174 | and exits.} You must use the same port number with the host @value{GDBN} |
| 10175 | @code{target remote} command. |
| 10176 | |
| 10177 | On some targets, @code{gdbserver} can also attach to running programs. |
| 10178 | This is accomplished via the @code{--attach} argument. The syntax is: |
| 10179 | |
| 10180 | @smallexample |
| 10181 | target> gdbserver @var{comm} --attach @var{pid} |
| 10182 | @end smallexample |
| 10183 | |
| 10184 | @var{pid} is the process ID of a currently running process. It isn't necessary |
| 10185 | to point @code{gdbserver} at a binary for the running process. |
| 10186 | |
| 10187 | @item On the @value{GDBN} host machine, |
| 10188 | you need an unstripped copy of your program, since @value{GDBN} needs |
| 10189 | symbols and debugging information. Start up @value{GDBN} as usual, |
| 10190 | using the name of the local copy of your program as the first argument. |
| 10191 | (You may also need the @w{@samp{--baud}} option if the serial line is |
| 10192 | running at anything other than 9600@dmn{bps}.) After that, use @code{target |
| 10193 | remote} to establish communications with @code{gdbserver}. Its argument |
| 10194 | is either a device name (usually a serial device, like |
| 10195 | @file{/dev/ttyb}), or a TCP port descriptor in the form |
| 10196 | @code{@var{host}:@var{PORT}}. For example: |
| 10197 | |
| 10198 | @smallexample |
| 10199 | (@value{GDBP}) target remote /dev/ttyb |
| 10200 | @end smallexample |
| 10201 | |
| 10202 | @noindent |
| 10203 | communicates with the server via serial line @file{/dev/ttyb}, and |
| 10204 | |
| 10205 | @smallexample |
| 10206 | (@value{GDBP}) target remote the-target:2345 |
| 10207 | @end smallexample |
| 10208 | |
| 10209 | @noindent |
| 10210 | communicates via a TCP connection to port 2345 on host @w{@file{the-target}}. |
| 10211 | For TCP connections, you must start up @code{gdbserver} prior to using |
| 10212 | the @code{target remote} command. Otherwise you may get an error whose |
| 10213 | text depends on the host system, but which usually looks something like |
| 10214 | @samp{Connection refused}. |
| 10215 | @end table |
| 10216 | |
| 10217 | @node NetWare |
| 10218 | @section Using the @code{gdbserve.nlm} program |
| 10219 | |
| 10220 | @kindex gdbserve.nlm |
| 10221 | @code{gdbserve.nlm} is a control program for NetWare systems, which |
| 10222 | allows you to connect your program with a remote @value{GDBN} via |
| 10223 | @code{target remote}. |
| 10224 | |
| 10225 | @value{GDBN} and @code{gdbserve.nlm} communicate via a serial line, |
| 10226 | using the standard @value{GDBN} remote serial protocol. |
| 10227 | |
| 10228 | @table @emph |
| 10229 | @item On the target machine, |
| 10230 | you need to have a copy of the program you want to debug. |
| 10231 | @code{gdbserve.nlm} does not need your program's symbol table, so you |
| 10232 | can strip the program if necessary to save space. @value{GDBN} on the |
| 10233 | host system does all the symbol handling. |
| 10234 | |
| 10235 | To use the server, you must tell it how to communicate with |
| 10236 | @value{GDBN}; the name of your program; and the arguments for your |
| 10237 | program. The syntax is: |
| 10238 | |
| 10239 | @smallexample |
| 10240 | load gdbserve [ BOARD=@var{board} ] [ PORT=@var{port} ] |
| 10241 | [ BAUD=@var{baud} ] @var{program} [ @var{args} @dots{} ] |
| 10242 | @end smallexample |
| 10243 | |
| 10244 | @var{board} and @var{port} specify the serial line; @var{baud} specifies |
| 10245 | the baud rate used by the connection. @var{port} and @var{node} default |
| 10246 | to 0, @var{baud} defaults to 9600@dmn{bps}. |
| 10247 | |
| 10248 | For example, to debug Emacs with the argument @samp{foo.txt}and |
| 10249 | communicate with @value{GDBN} over serial port number 2 or board 1 |
| 10250 | using a 19200@dmn{bps} connection: |
| 10251 | |
| 10252 | @smallexample |
| 10253 | load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt |
| 10254 | @end smallexample |
| 10255 | |
| 10256 | @item On the @value{GDBN} host machine, |
| 10257 | you need an unstripped copy of your program, since @value{GDBN} needs |
| 10258 | symbols and debugging information. Start up @value{GDBN} as usual, |
| 10259 | using the name of the local copy of your program as the first argument. |
| 10260 | (You may also need the @w{@samp{--baud}} option if the serial line is |
| 10261 | running at anything other than 9600@dmn{bps}. After that, use @code{target |
| 10262 | remote} to establish communications with @code{gdbserve.nlm}. Its |
| 10263 | argument is a device name (usually a serial device, like |
| 10264 | @file{/dev/ttyb}). For example: |
| 10265 | |
| 10266 | @smallexample |
| 10267 | (@value{GDBP}) target remote /dev/ttyb |
| 10268 | @end smallexample |
| 10269 | |
| 10270 | @noindent |
| 10271 | communications with the server via serial line @file{/dev/ttyb}. |
| 10272 | @end table |
| 10273 | |
| 10274 | @node remote stub |
| 10275 | @section Implementing a remote stub |
| 10276 | |
| 10277 | @cindex debugging stub, example |
| 10278 | @cindex remote stub, example |
| 10279 | @cindex stub example, remote debugging |
| 10280 | The stub files provided with @value{GDBN} implement the target side of the |
| 10281 | communication protocol, and the @value{GDBN} side is implemented in the |
| 10282 | @value{GDBN} source file @file{remote.c}. Normally, you can simply allow |
| 10283 | these subroutines to communicate, and ignore the details. (If you're |
| 10284 | implementing your own stub file, you can still ignore the details: start |
| 10285 | with one of the existing stub files. @file{sparc-stub.c} is the best |
| 10286 | organized, and therefore the easiest to read.) |
| 10287 | |
| 10288 | @cindex remote serial debugging, overview |
| 10289 | To debug a program running on another machine (the debugging |
| 10290 | @dfn{target} machine), you must first arrange for all the usual |
| 10291 | prerequisites for the program to run by itself. For example, for a C |
| 10292 | program, you need: |
| 10293 | |
| 10294 | @enumerate |
| 10295 | @item |
| 10296 | A startup routine to set up the C runtime environment; these usually |
| 10297 | have a name like @file{crt0}. The startup routine may be supplied by |
| 10298 | your hardware supplier, or you may have to write your own. |
| 10299 | |
| 10300 | @item |
| 10301 | A C subroutine library to support your program's |
| 10302 | subroutine calls, notably managing input and output. |
| 10303 | |
| 10304 | @item |
| 10305 | A way of getting your program to the other machine---for example, a |
| 10306 | download program. These are often supplied by the hardware |
| 10307 | manufacturer, but you may have to write your own from hardware |
| 10308 | documentation. |
| 10309 | @end enumerate |
| 10310 | |
| 10311 | The next step is to arrange for your program to use a serial port to |
| 10312 | communicate with the machine where @value{GDBN} is running (the @dfn{host} |
| 10313 | machine). In general terms, the scheme looks like this: |
| 10314 | |
| 10315 | @table @emph |
| 10316 | @item On the host, |
| 10317 | @value{GDBN} already understands how to use this protocol; when everything |
| 10318 | else is set up, you can simply use the @samp{target remote} command |
| 10319 | (@pxref{Targets,,Specifying a Debugging Target}). |
| 10320 | |
| 10321 | @item On the target, |
| 10322 | you must link with your program a few special-purpose subroutines that |
| 10323 | implement the @value{GDBN} remote serial protocol. The file containing these |
| 10324 | subroutines is called a @dfn{debugging stub}. |
| 10325 | |
| 10326 | On certain remote targets, you can use an auxiliary program |
| 10327 | @code{gdbserver} instead of linking a stub into your program. |
| 10328 | @xref{Server,,Using the @code{gdbserver} program}, for details. |
| 10329 | @end table |
| 10330 | |
| 10331 | The debugging stub is specific to the architecture of the remote |
| 10332 | machine; for example, use @file{sparc-stub.c} to debug programs on |
| 10333 | @sc{sparc} boards. |
| 10334 | |
| 10335 | @cindex remote serial stub list |
| 10336 | These working remote stubs are distributed with @value{GDBN}: |
| 10337 | |
| 10338 | @table @code |
| 10339 | |
| 10340 | @item i386-stub.c |
| 10341 | @cindex @file{i386-stub.c} |
| 10342 | @cindex Intel |
| 10343 | @cindex i386 |
| 10344 | For Intel 386 and compatible architectures. |
| 10345 | |
| 10346 | @item m68k-stub.c |
| 10347 | @cindex @file{m68k-stub.c} |
| 10348 | @cindex Motorola 680x0 |
| 10349 | @cindex m680x0 |
| 10350 | For Motorola 680x0 architectures. |
| 10351 | |
| 10352 | @item sh-stub.c |
| 10353 | @cindex @file{sh-stub.c} |
| 10354 | @cindex Hitachi |
| 10355 | @cindex SH |
| 10356 | For Hitachi SH architectures. |
| 10357 | |
| 10358 | @item sparc-stub.c |
| 10359 | @cindex @file{sparc-stub.c} |
| 10360 | @cindex Sparc |
| 10361 | For @sc{sparc} architectures. |
| 10362 | |
| 10363 | @item sparcl-stub.c |
| 10364 | @cindex @file{sparcl-stub.c} |
| 10365 | @cindex Fujitsu |
| 10366 | @cindex SparcLite |
| 10367 | For Fujitsu @sc{sparclite} architectures. |
| 10368 | |
| 10369 | @end table |
| 10370 | |
| 10371 | The @file{README} file in the @value{GDBN} distribution may list other |
| 10372 | recently added stubs. |
| 10373 | |
| 10374 | @menu |
| 10375 | * Stub Contents:: What the stub can do for you |
| 10376 | * Bootstrapping:: What you must do for the stub |
| 10377 | * Debug Session:: Putting it all together |
| 10378 | @end menu |
| 10379 | |
| 10380 | @node Stub Contents |
| 10381 | @subsection What the stub can do for you |
| 10382 | |
| 10383 | @cindex remote serial stub |
| 10384 | The debugging stub for your architecture supplies these three |
| 10385 | subroutines: |
| 10386 | |
| 10387 | @table @code |
| 10388 | @item set_debug_traps |
| 10389 | @kindex set_debug_traps |
| 10390 | @cindex remote serial stub, initialization |
| 10391 | This routine arranges for @code{handle_exception} to run when your |
| 10392 | program stops. You must call this subroutine explicitly near the |
| 10393 | beginning of your program. |
| 10394 | |
| 10395 | @item handle_exception |
| 10396 | @kindex handle_exception |
| 10397 | @cindex remote serial stub, main routine |
| 10398 | This is the central workhorse, but your program never calls it |
| 10399 | explicitly---the setup code arranges for @code{handle_exception} to |
| 10400 | run when a trap is triggered. |
| 10401 | |
| 10402 | @code{handle_exception} takes control when your program stops during |
| 10403 | execution (for example, on a breakpoint), and mediates communications |
| 10404 | with @value{GDBN} on the host machine. This is where the communications |
| 10405 | protocol is implemented; @code{handle_exception} acts as the @value{GDBN} |
| 10406 | representative on the target machine. It begins by sending summary |
| 10407 | information on the state of your program, then continues to execute, |
| 10408 | retrieving and transmitting any information @value{GDBN} needs, until you |
| 10409 | execute a @value{GDBN} command that makes your program resume; at that point, |
| 10410 | @code{handle_exception} returns control to your own code on the target |
| 10411 | machine. |
| 10412 | |
| 10413 | @item breakpoint |
| 10414 | @cindex @code{breakpoint} subroutine, remote |
| 10415 | Use this auxiliary subroutine to make your program contain a |
| 10416 | breakpoint. Depending on the particular situation, this may be the only |
| 10417 | way for @value{GDBN} to get control. For instance, if your target |
| 10418 | machine has some sort of interrupt button, you won't need to call this; |
| 10419 | pressing the interrupt button transfers control to |
| 10420 | @code{handle_exception}---in effect, to @value{GDBN}. On some machines, |
| 10421 | simply receiving characters on the serial port may also trigger a trap; |
| 10422 | again, in that situation, you don't need to call @code{breakpoint} from |
| 10423 | your own program---simply running @samp{target remote} from the host |
| 10424 | @value{GDBN} session gets control. |
| 10425 | |
| 10426 | Call @code{breakpoint} if none of these is true, or if you simply want |
| 10427 | to make certain your program stops at a predetermined point for the |
| 10428 | start of your debugging session. |
| 10429 | @end table |
| 10430 | |
| 10431 | @node Bootstrapping |
| 10432 | @subsection What you must do for the stub |
| 10433 | |
| 10434 | @cindex remote stub, support routines |
| 10435 | The debugging stubs that come with @value{GDBN} are set up for a particular |
| 10436 | chip architecture, but they have no information about the rest of your |
| 10437 | debugging target machine. |
| 10438 | |
| 10439 | First of all you need to tell the stub how to communicate with the |
| 10440 | serial port. |
| 10441 | |
| 10442 | @table @code |
| 10443 | @item int getDebugChar() |
| 10444 | @kindex getDebugChar |
| 10445 | Write this subroutine to read a single character from the serial port. |
| 10446 | It may be identical to @code{getchar} for your target system; a |
| 10447 | different name is used to allow you to distinguish the two if you wish. |
| 10448 | |
| 10449 | @item void putDebugChar(int) |
| 10450 | @kindex putDebugChar |
| 10451 | Write this subroutine to write a single character to the serial port. |
| 10452 | It may be identical to @code{putchar} for your target system; a |
| 10453 | different name is used to allow you to distinguish the two if you wish. |
| 10454 | @end table |
| 10455 | |
| 10456 | @cindex control C, and remote debugging |
| 10457 | @cindex interrupting remote targets |
| 10458 | If you want @value{GDBN} to be able to stop your program while it is |
| 10459 | running, you need to use an interrupt-driven serial driver, and arrange |
| 10460 | for it to stop when it receives a @code{^C} (@samp{\003}, the control-C |
| 10461 | character). That is the character which @value{GDBN} uses to tell the |
| 10462 | remote system to stop. |
| 10463 | |
| 10464 | Getting the debugging target to return the proper status to @value{GDBN} |
| 10465 | probably requires changes to the standard stub; one quick and dirty way |
| 10466 | is to just execute a breakpoint instruction (the ``dirty'' part is that |
| 10467 | @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). |
| 10468 | |
| 10469 | Other routines you need to supply are: |
| 10470 | |
| 10471 | @table @code |
| 10472 | @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) |
| 10473 | @kindex exceptionHandler |
| 10474 | Write this function to install @var{exception_address} in the exception |
| 10475 | handling tables. You need to do this because the stub does not have any |
| 10476 | way of knowing what the exception handling tables on your target system |
| 10477 | are like (for example, the processor's table might be in @sc{rom}, |
| 10478 | containing entries which point to a table in @sc{ram}). |
| 10479 | @var{exception_number} is the exception number which should be changed; |
| 10480 | its meaning is architecture-dependent (for example, different numbers |
| 10481 | might represent divide by zero, misaligned access, etc). When this |
| 10482 | exception occurs, control should be transferred directly to |
| 10483 | @var{exception_address}, and the processor state (stack, registers, |
| 10484 | and so on) should be just as it is when a processor exception occurs. So if |
| 10485 | you want to use a jump instruction to reach @var{exception_address}, it |
| 10486 | should be a simple jump, not a jump to subroutine. |
| 10487 | |
| 10488 | For the 386, @var{exception_address} should be installed as an interrupt |
| 10489 | gate so that interrupts are masked while the handler runs. The gate |
| 10490 | should be at privilege level 0 (the most privileged level). The |
| 10491 | @sc{sparc} and 68k stubs are able to mask interrupts themselves without |
| 10492 | help from @code{exceptionHandler}. |
| 10493 | |
| 10494 | @item void flush_i_cache() |
| 10495 | @kindex flush_i_cache |
| 10496 | On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the |
| 10497 | instruction cache, if any, on your target machine. If there is no |
| 10498 | instruction cache, this subroutine may be a no-op. |
| 10499 | |
| 10500 | On target machines that have instruction caches, @value{GDBN} requires this |
| 10501 | function to make certain that the state of your program is stable. |
| 10502 | @end table |
| 10503 | |
| 10504 | @noindent |
| 10505 | You must also make sure this library routine is available: |
| 10506 | |
| 10507 | @table @code |
| 10508 | @item void *memset(void *, int, int) |
| 10509 | @kindex memset |
| 10510 | This is the standard library function @code{memset} that sets an area of |
| 10511 | memory to a known value. If you have one of the free versions of |
| 10512 | @code{libc.a}, @code{memset} can be found there; otherwise, you must |
| 10513 | either obtain it from your hardware manufacturer, or write your own. |
| 10514 | @end table |
| 10515 | |
| 10516 | If you do not use the GNU C compiler, you may need other standard |
| 10517 | library subroutines as well; this varies from one stub to another, |
| 10518 | but in general the stubs are likely to use any of the common library |
| 10519 | subroutines which @code{@value{GCC}} generates as inline code. |
| 10520 | |
| 10521 | |
| 10522 | @node Debug Session |
| 10523 | @subsection Putting it all together |
| 10524 | |
| 10525 | @cindex remote serial debugging summary |
| 10526 | In summary, when your program is ready to debug, you must follow these |
| 10527 | steps. |
| 10528 | |
| 10529 | @enumerate |
| 10530 | @item |
| 10531 | Make sure you have defined the supporting low-level routines |
| 10532 | (@pxref{Bootstrapping,,What you must do for the stub}): |
| 10533 | @display |
| 10534 | @code{getDebugChar}, @code{putDebugChar}, |
| 10535 | @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. |
| 10536 | @end display |
| 10537 | |
| 10538 | @item |
| 10539 | Insert these lines near the top of your program: |
| 10540 | |
| 10541 | @smallexample |
| 10542 | set_debug_traps(); |
| 10543 | breakpoint(); |
| 10544 | @end smallexample |
| 10545 | |
| 10546 | @item |
| 10547 | For the 680x0 stub only, you need to provide a variable called |
| 10548 | @code{exceptionHook}. Normally you just use: |
| 10549 | |
| 10550 | @smallexample |
| 10551 | void (*exceptionHook)() = 0; |
| 10552 | @end smallexample |
| 10553 | |
| 10554 | @noindent |
| 10555 | but if before calling @code{set_debug_traps}, you set it to point to a |
| 10556 | function in your program, that function is called when |
| 10557 | @code{@value{GDBN}} continues after stopping on a trap (for example, bus |
| 10558 | error). The function indicated by @code{exceptionHook} is called with |
| 10559 | one parameter: an @code{int} which is the exception number. |
| 10560 | |
| 10561 | @item |
| 10562 | Compile and link together: your program, the @value{GDBN} debugging stub for |
| 10563 | your target architecture, and the supporting subroutines. |
| 10564 | |
| 10565 | @item |
| 10566 | Make sure you have a serial connection between your target machine and |
| 10567 | the @value{GDBN} host, and identify the serial port on the host. |
| 10568 | |
| 10569 | @item |
| 10570 | @c The "remote" target now provides a `load' command, so we should |
| 10571 | @c document that. FIXME. |
| 10572 | Download your program to your target machine (or get it there by |
| 10573 | whatever means the manufacturer provides), and start it. |
| 10574 | |
| 10575 | @item |
| 10576 | To start remote debugging, run @value{GDBN} on the host machine, and specify |
| 10577 | as an executable file the program that is running in the remote machine. |
| 10578 | This tells @value{GDBN} how to find your program's symbols and the contents |
| 10579 | of its pure text. |
| 10580 | |
| 10581 | @item |
| 10582 | @cindex serial line, @code{target remote} |
| 10583 | Establish communication using the @code{target remote} command. |
| 10584 | Its argument specifies how to communicate with the target |
| 10585 | machine---either via a devicename attached to a direct serial line, or a |
| 10586 | TCP or UDP port (usually to a terminal server which in turn has a serial line |
| 10587 | to the target). For example, to use a serial line connected to the |
| 10588 | device named @file{/dev/ttyb}: |
| 10589 | |
| 10590 | @smallexample |
| 10591 | target remote /dev/ttyb |
| 10592 | @end smallexample |
| 10593 | |
| 10594 | @cindex TCP port, @code{target remote} |
| 10595 | To use a TCP connection, use an argument of the form |
| 10596 | @code{@var{host}:@var{port}} or @code{tcp:@var{host}:@var{port}}. |
| 10597 | For example, to connect to port 2828 on a |
| 10598 | terminal server named @code{manyfarms}: |
| 10599 | |
| 10600 | @smallexample |
| 10601 | target remote manyfarms:2828 |
| 10602 | @end smallexample |
| 10603 | |
| 10604 | If your remote target is actually running on the same machine as |
| 10605 | your debugger session (e.g.@: a simulator of your target running on |
| 10606 | the same host), you can omit the hostname. For example, to connect |
| 10607 | to port 1234 on your local machine: |
| 10608 | |
| 10609 | @smallexample |
| 10610 | target remote :1234 |
| 10611 | @end smallexample |
| 10612 | @noindent |
| 10613 | |
| 10614 | Note that the colon is still required here. |
| 10615 | |
| 10616 | @cindex UDP port, @code{target remote} |
| 10617 | To use a UDP connection, use an argument of the form |
| 10618 | @code{udp:@var{host}:@var{port}}. For example, to connect to UDP port 2828 |
| 10619 | on a terminal server named @code{manyfarms}: |
| 10620 | |
| 10621 | @smallexample |
| 10622 | target remote udp:manyfarms:2828 |
| 10623 | @end smallexample |
| 10624 | |
| 10625 | When using a UDP connection for remote debugging, you should keep in mind |
| 10626 | that the `U' stands for ``Unreliable''. UDP can silently drop packets on |
| 10627 | busy or unreliable networks, which will cause havoc with your debugging |
| 10628 | session. |
| 10629 | |
| 10630 | @end enumerate |
| 10631 | |
| 10632 | Now you can use all the usual commands to examine and change data and to |
| 10633 | step and continue the remote program. |
| 10634 | |
| 10635 | To resume the remote program and stop debugging it, use the @code{detach} |
| 10636 | command. |
| 10637 | |
| 10638 | @cindex interrupting remote programs |
| 10639 | @cindex remote programs, interrupting |
| 10640 | Whenever @value{GDBN} is waiting for the remote program, if you type the |
| 10641 | interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the |
| 10642 | program. This may or may not succeed, depending in part on the hardware |
| 10643 | and the serial drivers the remote system uses. If you type the |
| 10644 | interrupt character once again, @value{GDBN} displays this prompt: |
| 10645 | |
| 10646 | @smallexample |
| 10647 | Interrupted while waiting for the program. |
| 10648 | Give up (and stop debugging it)? (y or n) |
| 10649 | @end smallexample |
| 10650 | |
| 10651 | If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. |
| 10652 | (If you decide you want to try again later, you can use @samp{target |
| 10653 | remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} |
| 10654 | goes back to waiting. |
| 10655 | |
| 10656 | |
| 10657 | @node Configurations |
| 10658 | @chapter Configuration-Specific Information |
| 10659 | |
| 10660 | While nearly all @value{GDBN} commands are available for all native and |
| 10661 | cross versions of the debugger, there are some exceptions. This chapter |
| 10662 | describes things that are only available in certain configurations. |
| 10663 | |
| 10664 | There are three major categories of configurations: native |
| 10665 | configurations, where the host and target are the same, embedded |
| 10666 | operating system configurations, which are usually the same for several |
| 10667 | different processor architectures, and bare embedded processors, which |
| 10668 | are quite different from each other. |
| 10669 | |
| 10670 | @menu |
| 10671 | * Native:: |
| 10672 | * Embedded OS:: |
| 10673 | * Embedded Processors:: |
| 10674 | * Architectures:: |
| 10675 | @end menu |
| 10676 | |
| 10677 | @node Native |
| 10678 | @section Native |
| 10679 | |
| 10680 | This section describes details specific to particular native |
| 10681 | configurations. |
| 10682 | |
| 10683 | @menu |
| 10684 | * HP-UX:: HP-UX |
| 10685 | * SVR4 Process Information:: SVR4 process information |
| 10686 | * DJGPP Native:: Features specific to the DJGPP port |
| 10687 | * Cygwin Native:: Features specific to the Cygwin port |
| 10688 | @end menu |
| 10689 | |
| 10690 | @node HP-UX |
| 10691 | @subsection HP-UX |
| 10692 | |
| 10693 | On HP-UX systems, if you refer to a function or variable name that |
| 10694 | begins with a dollar sign, @value{GDBN} searches for a user or system |
| 10695 | name first, before it searches for a convenience variable. |
| 10696 | |
| 10697 | @node SVR4 Process Information |
| 10698 | @subsection SVR4 process information |
| 10699 | |
| 10700 | @kindex /proc |
| 10701 | @cindex process image |
| 10702 | |
| 10703 | Many versions of SVR4 provide a facility called @samp{/proc} that can be |
| 10704 | used to examine the image of a running process using file-system |
| 10705 | subroutines. If @value{GDBN} is configured for an operating system with |
| 10706 | this facility, the command @code{info proc} is available to report on |
| 10707 | several kinds of information about the process running your program. |
| 10708 | @code{info proc} works only on SVR4 systems that include the |
| 10709 | @code{procfs} code. This includes OSF/1 (Digital Unix), Solaris, Irix, |
| 10710 | and Unixware, but not HP-UX or @sc{gnu}/Linux, for example. |
| 10711 | |
| 10712 | @table @code |
| 10713 | @kindex info proc |
| 10714 | @item info proc |
| 10715 | Summarize available information about the process. |
| 10716 | |
| 10717 | @kindex info proc mappings |
| 10718 | @item info proc mappings |
| 10719 | Report on the address ranges accessible in the program, with information |
| 10720 | on whether your program may read, write, or execute each range. |
| 10721 | @ignore |
| 10722 | @comment These sub-options of 'info proc' were not included when |
| 10723 | @comment procfs.c was re-written. Keep their descriptions around |
| 10724 | @comment against the day when someone finds the time to put them back in. |
| 10725 | @kindex info proc times |
| 10726 | @item info proc times |
| 10727 | Starting time, user CPU time, and system CPU time for your program and |
| 10728 | its children. |
| 10729 | |
| 10730 | @kindex info proc id |
| 10731 | @item info proc id |
| 10732 | Report on the process IDs related to your program: its own process ID, |
| 10733 | the ID of its parent, the process group ID, and the session ID. |
| 10734 | |
| 10735 | @kindex info proc status |
| 10736 | @item info proc status |
| 10737 | General information on the state of the process. If the process is |
| 10738 | stopped, this report includes the reason for stopping, and any signal |
| 10739 | received. |
| 10740 | |
| 10741 | @item info proc all |
| 10742 | Show all the above information about the process. |
| 10743 | @end ignore |
| 10744 | @end table |
| 10745 | |
| 10746 | @node DJGPP Native |
| 10747 | @subsection Features for Debugging @sc{djgpp} Programs |
| 10748 | @cindex @sc{djgpp} debugging |
| 10749 | @cindex native @sc{djgpp} debugging |
| 10750 | @cindex MS-DOS-specific commands |
| 10751 | |
| 10752 | @sc{djgpp} is the port of @sc{gnu} development tools to MS-DOS and |
| 10753 | MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs |
| 10754 | that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on |
| 10755 | top of real-mode DOS systems and their emulations. |
| 10756 | |
| 10757 | @value{GDBN} supports native debugging of @sc{djgpp} programs, and |
| 10758 | defines a few commands specific to the @sc{djgpp} port. This |
| 10759 | subsection describes those commands. |
| 10760 | |
| 10761 | @table @code |
| 10762 | @kindex info dos |
| 10763 | @item info dos |
| 10764 | This is a prefix of @sc{djgpp}-specific commands which print |
| 10765 | information about the target system and important OS structures. |
| 10766 | |
| 10767 | @kindex sysinfo |
| 10768 | @cindex MS-DOS system info |
| 10769 | @cindex free memory information (MS-DOS) |
| 10770 | @item info dos sysinfo |
| 10771 | This command displays assorted information about the underlying |
| 10772 | platform: the CPU type and features, the OS version and flavor, the |
| 10773 | DPMI version, and the available conventional and DPMI memory. |
| 10774 | |
| 10775 | @cindex GDT |
| 10776 | @cindex LDT |
| 10777 | @cindex IDT |
| 10778 | @cindex segment descriptor tables |
| 10779 | @cindex descriptor tables display |
| 10780 | @item info dos gdt |
| 10781 | @itemx info dos ldt |
| 10782 | @itemx info dos idt |
| 10783 | These 3 commands display entries from, respectively, Global, Local, |
| 10784 | and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor |
| 10785 | tables are data structures which store a descriptor for each segment |
| 10786 | that is currently in use. The segment's selector is an index into a |
| 10787 | descriptor table; the table entry for that index holds the |
| 10788 | descriptor's base address and limit, and its attributes and access |
| 10789 | rights. |
| 10790 | |
| 10791 | A typical @sc{djgpp} program uses 3 segments: a code segment, a data |
| 10792 | segment (used for both data and the stack), and a DOS segment (which |
| 10793 | allows access to DOS/BIOS data structures and absolute addresses in |
| 10794 | conventional memory). However, the DPMI host will usually define |
| 10795 | additional segments in order to support the DPMI environment. |
| 10796 | |
| 10797 | @cindex garbled pointers |
| 10798 | These commands allow to display entries from the descriptor tables. |
| 10799 | Without an argument, all entries from the specified table are |
| 10800 | displayed. An argument, which should be an integer expression, means |
| 10801 | display a single entry whose index is given by the argument. For |
| 10802 | example, here's a convenient way to display information about the |
| 10803 | debugged program's data segment: |
| 10804 | |
| 10805 | @smallexample |
| 10806 | @exdent @code{(@value{GDBP}) info dos ldt $ds} |
| 10807 | @exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)} |
| 10808 | @end smallexample |
| 10809 | |
| 10810 | @noindent |
| 10811 | This comes in handy when you want to see whether a pointer is outside |
| 10812 | the data segment's limit (i.e.@: @dfn{garbled}). |
| 10813 | |
| 10814 | @cindex page tables display (MS-DOS) |
| 10815 | @item info dos pde |
| 10816 | @itemx info dos pte |
| 10817 | These two commands display entries from, respectively, the Page |
| 10818 | Directory and the Page Tables. Page Directories and Page Tables are |
| 10819 | data structures which control how virtual memory addresses are mapped |
| 10820 | into physical addresses. A Page Table includes an entry for every |
| 10821 | page of memory that is mapped into the program's address space; there |
| 10822 | may be several Page Tables, each one holding up to 4096 entries. A |
| 10823 | Page Directory has up to 4096 entries, one each for every Page Table |
| 10824 | that is currently in use. |
| 10825 | |
| 10826 | Without an argument, @kbd{info dos pde} displays the entire Page |
| 10827 | Directory, and @kbd{info dos pte} displays all the entries in all of |
| 10828 | the Page Tables. An argument, an integer expression, given to the |
| 10829 | @kbd{info dos pde} command means display only that entry from the Page |
| 10830 | Directory table. An argument given to the @kbd{info dos pte} command |
| 10831 | means display entries from a single Page Table, the one pointed to by |
| 10832 | the specified entry in the Page Directory. |
| 10833 | |
| 10834 | @cindex direct memory access (DMA) on MS-DOS |
| 10835 | These commands are useful when your program uses @dfn{DMA} (Direct |
| 10836 | Memory Access), which needs physical addresses to program the DMA |
| 10837 | controller. |
| 10838 | |
| 10839 | These commands are supported only with some DPMI servers. |
| 10840 | |
| 10841 | @cindex physical address from linear address |
| 10842 | @item info dos address-pte @var{addr} |
| 10843 | This command displays the Page Table entry for a specified linear |
| 10844 | address. The argument linear address @var{addr} should already have the |
| 10845 | appropriate segment's base address added to it, because this command |
| 10846 | accepts addresses which may belong to @emph{any} segment. For |
| 10847 | example, here's how to display the Page Table entry for the page where |
| 10848 | the variable @code{i} is stored: |
| 10849 | |
| 10850 | @smallexample |
| 10851 | @exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i} |
| 10852 | @exdent @code{Page Table entry for address 0x11a00d30:} |
| 10853 | @exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30} |
| 10854 | @end smallexample |
| 10855 | |
| 10856 | @noindent |
| 10857 | This says that @code{i} is stored at offset @code{0xd30} from the page |
| 10858 | whose physical base address is @code{0x02698000}, and prints all the |
| 10859 | attributes of that page. |
| 10860 | |
| 10861 | Note that you must cast the addresses of variables to a @code{char *}, |
| 10862 | since otherwise the value of @code{__djgpp_base_address}, the base |
| 10863 | address of all variables and functions in a @sc{djgpp} program, will |
| 10864 | be added using the rules of C pointer arithmetics: if @code{i} is |
| 10865 | declared an @code{int}, @value{GDBN} will add 4 times the value of |
| 10866 | @code{__djgpp_base_address} to the address of @code{i}. |
| 10867 | |
| 10868 | Here's another example, it displays the Page Table entry for the |
| 10869 | transfer buffer: |
| 10870 | |
| 10871 | @smallexample |
| 10872 | @exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)} |
| 10873 | @exdent @code{Page Table entry for address 0x29110:} |
| 10874 | @exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110} |
| 10875 | @end smallexample |
| 10876 | |
| 10877 | @noindent |
| 10878 | (The @code{+ 3} offset is because the transfer buffer's address is the |
| 10879 | 3rd member of the @code{_go32_info_block} structure.) The output of |
| 10880 | this command clearly shows that addresses in conventional memory are |
| 10881 | mapped 1:1, i.e.@: the physical and linear addresses are identical. |
| 10882 | |
| 10883 | This command is supported only with some DPMI servers. |
| 10884 | @end table |
| 10885 | |
| 10886 | @node Cygwin Native |
| 10887 | @subsection Features for Debugging MS Windows PE executables |
| 10888 | @cindex MS Windows debugging |
| 10889 | @cindex native Cygwin debugging |
| 10890 | @cindex Cygwin-specific commands |
| 10891 | |
| 10892 | @value{GDBN} supports native debugging of MS Windows programs, and |
| 10893 | defines a few commands specific to the Cygwin port. This |
| 10894 | subsection describes those commands. |
| 10895 | |
| 10896 | @table @code |
| 10897 | @kindex info w32 |
| 10898 | @item info w32 |
| 10899 | This is a prefix of MS Windows specific commands which print |
| 10900 | information about the target system and important OS structures. |
| 10901 | |
| 10902 | @item info w32 selector |
| 10903 | This command displays information returned by |
| 10904 | the Win32 API @code{GetThreadSelectorEntry} function. |
| 10905 | It takes an optional argument that is evaluated to |
| 10906 | a long value to give the information about this given selector. |
| 10907 | Without argument, this command displays information |
| 10908 | about the the six segment registers. |
| 10909 | |
| 10910 | @kindex info dll |
| 10911 | @item info dll |
| 10912 | This is a Cygwin specific alias of info shared. |
| 10913 | |
| 10914 | @kindex dll-symbols |
| 10915 | @item dll-symbols |
| 10916 | This command loads symbols from a dll similarly to |
| 10917 | add-sym command but without the need to specify a base address. |
| 10918 | |
| 10919 | @kindex set new-console |
| 10920 | @item set new-console @var{mode} |
| 10921 | If @var{mode} is @code{on} the debuggee will |
| 10922 | be started in a new console on next start. |
| 10923 | If @var{mode} is @code{off}i, the debuggee will |
| 10924 | be started in the same console as the debugger. |
| 10925 | |
| 10926 | @kindex show new-console |
| 10927 | @item show new-console |
| 10928 | Displays whether a new console is used |
| 10929 | when the debuggee is started. |
| 10930 | |
| 10931 | @kindex set new-group |
| 10932 | @item set new-group @var{mode} |
| 10933 | This boolean value controls whether the debuggee should |
| 10934 | start a new group or stay in the same group as the debugger. |
| 10935 | This affects the way the Windows OS handles |
| 10936 | Ctrl-C. |
| 10937 | |
| 10938 | @kindex show new-group |
| 10939 | @item show new-group |
| 10940 | Displays current value of new-group boolean. |
| 10941 | |
| 10942 | @kindex set debugevents |
| 10943 | @item set debugevents |
| 10944 | This boolean value adds debug output concerning events seen by the debugger. |
| 10945 | |
| 10946 | @kindex set debugexec |
| 10947 | @item set debugexec |
| 10948 | This boolean value adds debug output concerning execute events |
| 10949 | seen by the debugger. |
| 10950 | |
| 10951 | @kindex set debugexceptions |
| 10952 | @item set debugexceptions |
| 10953 | This boolean value adds debug ouptut concerning exception events |
| 10954 | seen by the debugger. |
| 10955 | |
| 10956 | @kindex set debugmemory |
| 10957 | @item set debugmemory |
| 10958 | This boolean value adds debug ouptut concerning memory events |
| 10959 | seen by the debugger. |
| 10960 | |
| 10961 | @kindex set shell |
| 10962 | @item set shell |
| 10963 | This boolean values specifies whether the debuggee is called |
| 10964 | via a shell or directly (default value is on). |
| 10965 | |
| 10966 | @kindex show shell |
| 10967 | @item show shell |
| 10968 | Displays if the debuggee will be started with a shell. |
| 10969 | |
| 10970 | @end table |
| 10971 | |
| 10972 | @node Embedded OS |
| 10973 | @section Embedded Operating Systems |
| 10974 | |
| 10975 | This section describes configurations involving the debugging of |
| 10976 | embedded operating systems that are available for several different |
| 10977 | architectures. |
| 10978 | |
| 10979 | @menu |
| 10980 | * VxWorks:: Using @value{GDBN} with VxWorks |
| 10981 | @end menu |
| 10982 | |
| 10983 | @value{GDBN} includes the ability to debug programs running on |
| 10984 | various real-time operating systems. |
| 10985 | |
| 10986 | @node VxWorks |
| 10987 | @subsection Using @value{GDBN} with VxWorks |
| 10988 | |
| 10989 | @cindex VxWorks |
| 10990 | |
| 10991 | @table @code |
| 10992 | |
| 10993 | @kindex target vxworks |
| 10994 | @item target vxworks @var{machinename} |
| 10995 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} |
| 10996 | is the target system's machine name or IP address. |
| 10997 | |
| 10998 | @end table |
| 10999 | |
| 11000 | On VxWorks, @code{load} links @var{filename} dynamically on the |
| 11001 | current target system as well as adding its symbols in @value{GDBN}. |
| 11002 | |
| 11003 | @value{GDBN} enables developers to spawn and debug tasks running on networked |
| 11004 | VxWorks targets from a Unix host. Already-running tasks spawned from |
| 11005 | the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on |
| 11006 | both the Unix host and on the VxWorks target. The program |
| 11007 | @code{@value{GDBP}} is installed and executed on the Unix host. (It may be |
| 11008 | installed with the name @code{vxgdb}, to distinguish it from a |
| 11009 | @value{GDBN} for debugging programs on the host itself.) |
| 11010 | |
| 11011 | @table @code |
| 11012 | @item VxWorks-timeout @var{args} |
| 11013 | @kindex vxworks-timeout |
| 11014 | All VxWorks-based targets now support the option @code{vxworks-timeout}. |
| 11015 | This option is set by the user, and @var{args} represents the number of |
| 11016 | seconds @value{GDBN} waits for responses to rpc's. You might use this if |
| 11017 | your VxWorks target is a slow software simulator or is on the far side |
| 11018 | of a thin network line. |
| 11019 | @end table |
| 11020 | |
| 11021 | The following information on connecting to VxWorks was current when |
| 11022 | this manual was produced; newer releases of VxWorks may use revised |
| 11023 | procedures. |
| 11024 | |
| 11025 | @kindex INCLUDE_RDB |
| 11026 | To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel |
| 11027 | to include the remote debugging interface routines in the VxWorks |
| 11028 | library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the |
| 11029 | VxWorks configuration file @file{configAll.h} and rebuild your VxWorks |
| 11030 | kernel. The resulting kernel contains @file{rdb.a}, and spawns the |
| 11031 | source debugging task @code{tRdbTask} when VxWorks is booted. For more |
| 11032 | information on configuring and remaking VxWorks, see the manufacturer's |
| 11033 | manual. |
| 11034 | @c VxWorks, see the @cite{VxWorks Programmer's Guide}. |
| 11035 | |
| 11036 | Once you have included @file{rdb.a} in your VxWorks system image and set |
| 11037 | your Unix execution search path to find @value{GDBN}, you are ready to |
| 11038 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or |
| 11039 | @code{vxgdb}, depending on your installation). |
| 11040 | |
| 11041 | @value{GDBN} comes up showing the prompt: |
| 11042 | |
| 11043 | @smallexample |
| 11044 | (vxgdb) |
| 11045 | @end smallexample |
| 11046 | |
| 11047 | @menu |
| 11048 | * VxWorks Connection:: Connecting to VxWorks |
| 11049 | * VxWorks Download:: VxWorks download |
| 11050 | * VxWorks Attach:: Running tasks |
| 11051 | @end menu |
| 11052 | |
| 11053 | @node VxWorks Connection |
| 11054 | @subsubsection Connecting to VxWorks |
| 11055 | |
| 11056 | The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the |
| 11057 | network. To connect to a target whose host name is ``@code{tt}'', type: |
| 11058 | |
| 11059 | @smallexample |
| 11060 | (vxgdb) target vxworks tt |
| 11061 | @end smallexample |
| 11062 | |
| 11063 | @need 750 |
| 11064 | @value{GDBN} displays messages like these: |
| 11065 | |
| 11066 | @smallexample |
| 11067 | Attaching remote machine across net... |
| 11068 | Connected to tt. |
| 11069 | @end smallexample |
| 11070 | |
| 11071 | @need 1000 |
| 11072 | @value{GDBN} then attempts to read the symbol tables of any object modules |
| 11073 | loaded into the VxWorks target since it was last booted. @value{GDBN} locates |
| 11074 | these files by searching the directories listed in the command search |
| 11075 | path (@pxref{Environment, ,Your program's environment}); if it fails |
| 11076 | to find an object file, it displays a message such as: |
| 11077 | |
| 11078 | @smallexample |
| 11079 | prog.o: No such file or directory. |
| 11080 | @end smallexample |
| 11081 | |
| 11082 | When this happens, add the appropriate directory to the search path with |
| 11083 | the @value{GDBN} command @code{path}, and execute the @code{target} |
| 11084 | command again. |
| 11085 | |
| 11086 | @node VxWorks Download |
| 11087 | @subsubsection VxWorks download |
| 11088 | |
| 11089 | @cindex download to VxWorks |
| 11090 | If you have connected to the VxWorks target and you want to debug an |
| 11091 | object that has not yet been loaded, you can use the @value{GDBN} |
| 11092 | @code{load} command to download a file from Unix to VxWorks |
| 11093 | incrementally. The object file given as an argument to the @code{load} |
| 11094 | command is actually opened twice: first by the VxWorks target in order |
| 11095 | to download the code, then by @value{GDBN} in order to read the symbol |
| 11096 | table. This can lead to problems if the current working directories on |
| 11097 | the two systems differ. If both systems have NFS mounted the same |
| 11098 | filesystems, you can avoid these problems by using absolute paths. |
| 11099 | Otherwise, it is simplest to set the working directory on both systems |
| 11100 | to the directory in which the object file resides, and then to reference |
| 11101 | the file by its name, without any path. For instance, a program |
| 11102 | @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks |
| 11103 | and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this |
| 11104 | program, type this on VxWorks: |
| 11105 | |
| 11106 | @smallexample |
| 11107 | -> cd "@var{vxpath}/vw/demo/rdb" |
| 11108 | @end smallexample |
| 11109 | |
| 11110 | @noindent |
| 11111 | Then, in @value{GDBN}, type: |
| 11112 | |
| 11113 | @smallexample |
| 11114 | (vxgdb) cd @var{hostpath}/vw/demo/rdb |
| 11115 | (vxgdb) load prog.o |
| 11116 | @end smallexample |
| 11117 | |
| 11118 | @value{GDBN} displays a response similar to this: |
| 11119 | |
| 11120 | @smallexample |
| 11121 | Reading symbol data from wherever/vw/demo/rdb/prog.o... done. |
| 11122 | @end smallexample |
| 11123 | |
| 11124 | You can also use the @code{load} command to reload an object module |
| 11125 | after editing and recompiling the corresponding source file. Note that |
| 11126 | this makes @value{GDBN} delete all currently-defined breakpoints, |
| 11127 | auto-displays, and convenience variables, and to clear the value |
| 11128 | history. (This is necessary in order to preserve the integrity of |
| 11129 | debugger's data structures that reference the target system's symbol |
| 11130 | table.) |
| 11131 | |
| 11132 | @node VxWorks Attach |
| 11133 | @subsubsection Running tasks |
| 11134 | |
| 11135 | @cindex running VxWorks tasks |
| 11136 | You can also attach to an existing task using the @code{attach} command as |
| 11137 | follows: |
| 11138 | |
| 11139 | @smallexample |
| 11140 | (vxgdb) attach @var{task} |
| 11141 | @end smallexample |
| 11142 | |
| 11143 | @noindent |
| 11144 | where @var{task} is the VxWorks hexadecimal task ID. The task can be running |
| 11145 | or suspended when you attach to it. Running tasks are suspended at |
| 11146 | the time of attachment. |
| 11147 | |
| 11148 | @node Embedded Processors |
| 11149 | @section Embedded Processors |
| 11150 | |
| 11151 | This section goes into details specific to particular embedded |
| 11152 | configurations. |
| 11153 | |
| 11154 | |
| 11155 | @menu |
| 11156 | * ARM:: ARM |
| 11157 | * H8/300:: Hitachi H8/300 |
| 11158 | * H8/500:: Hitachi H8/500 |
| 11159 | * i960:: Intel i960 |
| 11160 | * M32R/D:: Mitsubishi M32R/D |
| 11161 | * M68K:: Motorola M68K |
| 11162 | * MIPS Embedded:: MIPS Embedded |
| 11163 | * OpenRISC 1000:: OpenRisc 1000 |
| 11164 | * PA:: HP PA Embedded |
| 11165 | * PowerPC: PowerPC |
| 11166 | * SH:: Hitachi SH |
| 11167 | * Sparclet:: Tsqware Sparclet |
| 11168 | * Sparclite:: Fujitsu Sparclite |
| 11169 | * ST2000:: Tandem ST2000 |
| 11170 | * Z8000:: Zilog Z8000 |
| 11171 | @end menu |
| 11172 | |
| 11173 | @node ARM |
| 11174 | @subsection ARM |
| 11175 | |
| 11176 | @table @code |
| 11177 | |
| 11178 | @kindex target rdi |
| 11179 | @item target rdi @var{dev} |
| 11180 | ARM Angel monitor, via RDI library interface to ADP protocol. You may |
| 11181 | use this target to communicate with both boards running the Angel |
| 11182 | monitor, or with the EmbeddedICE JTAG debug device. |
| 11183 | |
| 11184 | @kindex target rdp |
| 11185 | @item target rdp @var{dev} |
| 11186 | ARM Demon monitor. |
| 11187 | |
| 11188 | @end table |
| 11189 | |
| 11190 | @node H8/300 |
| 11191 | @subsection Hitachi H8/300 |
| 11192 | |
| 11193 | @table @code |
| 11194 | |
| 11195 | @kindex target hms@r{, with H8/300} |
| 11196 | @item target hms @var{dev} |
| 11197 | A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. |
| 11198 | Use special commands @code{device} and @code{speed} to control the serial |
| 11199 | line and the communications speed used. |
| 11200 | |
| 11201 | @kindex target e7000@r{, with H8/300} |
| 11202 | @item target e7000 @var{dev} |
| 11203 | E7000 emulator for Hitachi H8 and SH. |
| 11204 | |
| 11205 | @kindex target sh3@r{, with H8/300} |
| 11206 | @kindex target sh3e@r{, with H8/300} |
| 11207 | @item target sh3 @var{dev} |
| 11208 | @itemx target sh3e @var{dev} |
| 11209 | Hitachi SH-3 and SH-3E target systems. |
| 11210 | |
| 11211 | @end table |
| 11212 | |
| 11213 | @cindex download to H8/300 or H8/500 |
| 11214 | @cindex H8/300 or H8/500 download |
| 11215 | @cindex download to Hitachi SH |
| 11216 | @cindex Hitachi SH download |
| 11217 | When you select remote debugging to a Hitachi SH, H8/300, or H8/500 |
| 11218 | board, the @code{load} command downloads your program to the Hitachi |
| 11219 | board and also opens it as the current executable target for |
| 11220 | @value{GDBN} on your host (like the @code{file} command). |
| 11221 | |
| 11222 | @value{GDBN} needs to know these things to talk to your |
| 11223 | Hitachi SH, H8/300, or H8/500: |
| 11224 | |
| 11225 | @enumerate |
| 11226 | @item |
| 11227 | that you want to use @samp{target hms}, the remote debugging interface |
| 11228 | for Hitachi microprocessors, or @samp{target e7000}, the in-circuit |
| 11229 | emulator for the Hitachi SH and the Hitachi 300H. (@samp{target hms} is |
| 11230 | the default when @value{GDBN} is configured specifically for the Hitachi SH, |
| 11231 | H8/300, or H8/500.) |
| 11232 | |
| 11233 | @item |
| 11234 | what serial device connects your host to your Hitachi board (the first |
| 11235 | serial device available on your host is the default). |
| 11236 | |
| 11237 | @item |
| 11238 | what speed to use over the serial device. |
| 11239 | @end enumerate |
| 11240 | |
| 11241 | @menu |
| 11242 | * Hitachi Boards:: Connecting to Hitachi boards. |
| 11243 | * Hitachi ICE:: Using the E7000 In-Circuit Emulator. |
| 11244 | * Hitachi Special:: Special @value{GDBN} commands for Hitachi micros. |
| 11245 | @end menu |
| 11246 | |
| 11247 | @node Hitachi Boards |
| 11248 | @subsubsection Connecting to Hitachi boards |
| 11249 | |
| 11250 | @c only for Unix hosts |
| 11251 | @kindex device |
| 11252 | @cindex serial device, Hitachi micros |
| 11253 | Use the special @code{@value{GDBN}} command @samp{device @var{port}} if you |
| 11254 | need to explicitly set the serial device. The default @var{port} is the |
| 11255 | first available port on your host. This is only necessary on Unix |
| 11256 | hosts, where it is typically something like @file{/dev/ttya}. |
| 11257 | |
| 11258 | @kindex speed |
| 11259 | @cindex serial line speed, Hitachi micros |
| 11260 | @code{@value{GDBN}} has another special command to set the communications |
| 11261 | speed: @samp{speed @var{bps}}. This command also is only used from Unix |
| 11262 | hosts; on DOS hosts, set the line speed as usual from outside @value{GDBN} with |
| 11263 | the DOS @code{mode} command (for instance, |
| 11264 | @w{@kbd{mode com2:9600,n,8,1,p}} for a 9600@dmn{bps} connection). |
| 11265 | |
| 11266 | The @samp{device} and @samp{speed} commands are available only when you |
| 11267 | use a Unix host to debug your Hitachi microprocessor programs. If you |
| 11268 | use a DOS host, |
| 11269 | @value{GDBN} depends on an auxiliary terminate-and-stay-resident program |
| 11270 | called @code{asynctsr} to communicate with the development board |
| 11271 | through a PC serial port. You must also use the DOS @code{mode} command |
| 11272 | to set up the serial port on the DOS side. |
| 11273 | |
| 11274 | The following sample session illustrates the steps needed to start a |
| 11275 | program under @value{GDBN} control on an H8/300. The example uses a |
| 11276 | sample H8/300 program called @file{t.x}. The procedure is the same for |
| 11277 | the Hitachi SH and the H8/500. |
| 11278 | |
| 11279 | First hook up your development board. In this example, we use a |
| 11280 | board attached to serial port @code{COM2}; if you use a different serial |
| 11281 | port, substitute its name in the argument of the @code{mode} command. |
| 11282 | When you call @code{asynctsr}, the auxiliary comms program used by the |
| 11283 | debugger, you give it just the numeric part of the serial port's name; |
| 11284 | for example, @samp{asyncstr 2} below runs @code{asyncstr} on |
| 11285 | @code{COM2}. |
| 11286 | |
| 11287 | @smallexample |
| 11288 | C:\H8300\TEST> asynctsr 2 |
| 11289 | C:\H8300\TEST> mode com2:9600,n,8,1,p |
| 11290 | |
| 11291 | Resident portion of MODE loaded |
| 11292 | |
| 11293 | COM2: 9600, n, 8, 1, p |
| 11294 | |
| 11295 | @end smallexample |
| 11296 | |
| 11297 | @quotation |
| 11298 | @emph{Warning:} We have noticed a bug in PC-NFS that conflicts with |
| 11299 | @code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to |
| 11300 | disable it, or even boot without it, to use @code{asynctsr} to control |
| 11301 | your development board. |
| 11302 | @end quotation |
| 11303 | |
| 11304 | @kindex target hms@r{, and serial protocol} |
| 11305 | Now that serial communications are set up, and the development board is |
| 11306 | connected, you can start up @value{GDBN}. Call @code{@value{GDBP}} with |
| 11307 | the name of your program as the argument. @code{@value{GDBN}} prompts |
| 11308 | you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special |
| 11309 | commands to begin your debugging session: @samp{target hms} to specify |
| 11310 | cross-debugging to the Hitachi board, and the @code{load} command to |
| 11311 | download your program to the board. @code{load} displays the names of |
| 11312 | the program's sections, and a @samp{*} for each 2K of data downloaded. |
| 11313 | (If you want to refresh @value{GDBN} data on symbols or on the |
| 11314 | executable file without downloading, use the @value{GDBN} commands |
| 11315 | @code{file} or @code{symbol-file}. These commands, and @code{load} |
| 11316 | itself, are described in @ref{Files,,Commands to specify files}.) |
| 11317 | |
| 11318 | @smallexample |
| 11319 | (eg-C:\H8300\TEST) @value{GDBP} t.x |
| 11320 | @value{GDBN} is free software and you are welcome to distribute copies |
| 11321 | of it under certain conditions; type "show copying" to see |
| 11322 | the conditions. |
| 11323 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
| 11324 | for details. |
| 11325 | @value{GDBN} @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc... |
| 11326 | (@value{GDBP}) target hms |
| 11327 | Connected to remote H8/300 HMS system. |
| 11328 | (@value{GDBP}) load t.x |
| 11329 | .text : 0x8000 .. 0xabde *********** |
| 11330 | .data : 0xabde .. 0xad30 * |
| 11331 | .stack : 0xf000 .. 0xf014 * |
| 11332 | @end smallexample |
| 11333 | |
| 11334 | At this point, you're ready to run or debug your program. From here on, |
| 11335 | you can use all the usual @value{GDBN} commands. The @code{break} command |
| 11336 | sets breakpoints; the @code{run} command starts your program; |
| 11337 | @code{print} or @code{x} display data; the @code{continue} command |
| 11338 | resumes execution after stopping at a breakpoint. You can use the |
| 11339 | @code{help} command at any time to find out more about @value{GDBN} commands. |
| 11340 | |
| 11341 | Remember, however, that @emph{operating system} facilities aren't |
| 11342 | available on your development board; for example, if your program hangs, |
| 11343 | you can't send an interrupt---but you can press the @sc{reset} switch! |
| 11344 | |
| 11345 | Use the @sc{reset} button on the development board |
| 11346 | @itemize @bullet |
| 11347 | @item |
| 11348 | to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has |
| 11349 | no way to pass an interrupt signal to the development board); and |
| 11350 | |
| 11351 | @item |
| 11352 | to return to the @value{GDBN} command prompt after your program finishes |
| 11353 | normally. The communications protocol provides no other way for @value{GDBN} |
| 11354 | to detect program completion. |
| 11355 | @end itemize |
| 11356 | |
| 11357 | In either case, @value{GDBN} sees the effect of a @sc{reset} on the |
| 11358 | development board as a ``normal exit'' of your program. |
| 11359 | |
| 11360 | @node Hitachi ICE |
| 11361 | @subsubsection Using the E7000 in-circuit emulator |
| 11362 | |
| 11363 | @kindex target e7000@r{, with Hitachi ICE} |
| 11364 | You can use the E7000 in-circuit emulator to develop code for either the |
| 11365 | Hitachi SH or the H8/300H. Use one of these forms of the @samp{target |
| 11366 | e7000} command to connect @value{GDBN} to your E7000: |
| 11367 | |
| 11368 | @table @code |
| 11369 | @item target e7000 @var{port} @var{speed} |
| 11370 | Use this form if your E7000 is connected to a serial port. The |
| 11371 | @var{port} argument identifies what serial port to use (for example, |
| 11372 | @samp{com2}). The third argument is the line speed in bits per second |
| 11373 | (for example, @samp{9600}). |
| 11374 | |
| 11375 | @item target e7000 @var{hostname} |
| 11376 | If your E7000 is installed as a host on a TCP/IP network, you can just |
| 11377 | specify its hostname; @value{GDBN} uses @code{telnet} to connect. |
| 11378 | @end table |
| 11379 | |
| 11380 | @node Hitachi Special |
| 11381 | @subsubsection Special @value{GDBN} commands for Hitachi micros |
| 11382 | |
| 11383 | Some @value{GDBN} commands are available only for the H8/300: |
| 11384 | |
| 11385 | @table @code |
| 11386 | |
| 11387 | @kindex set machine |
| 11388 | @kindex show machine |
| 11389 | @item set machine h8300 |
| 11390 | @itemx set machine h8300h |
| 11391 | Condition @value{GDBN} for one of the two variants of the H8/300 |
| 11392 | architecture with @samp{set machine}. You can use @samp{show machine} |
| 11393 | to check which variant is currently in effect. |
| 11394 | |
| 11395 | @end table |
| 11396 | |
| 11397 | @node H8/500 |
| 11398 | @subsection H8/500 |
| 11399 | |
| 11400 | @table @code |
| 11401 | |
| 11402 | @kindex set memory @var{mod} |
| 11403 | @cindex memory models, H8/500 |
| 11404 | @item set memory @var{mod} |
| 11405 | @itemx show memory |
| 11406 | Specify which H8/500 memory model (@var{mod}) you are using with |
| 11407 | @samp{set memory}; check which memory model is in effect with @samp{show |
| 11408 | memory}. The accepted values for @var{mod} are @code{small}, |
| 11409 | @code{big}, @code{medium}, and @code{compact}. |
| 11410 | |
| 11411 | @end table |
| 11412 | |
| 11413 | @node i960 |
| 11414 | @subsection Intel i960 |
| 11415 | |
| 11416 | @table @code |
| 11417 | |
| 11418 | @kindex target mon960 |
| 11419 | @item target mon960 @var{dev} |
| 11420 | MON960 monitor for Intel i960. |
| 11421 | |
| 11422 | @kindex target nindy |
| 11423 | @item target nindy @var{devicename} |
| 11424 | An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is |
| 11425 | the name of the serial device to use for the connection, e.g. |
| 11426 | @file{/dev/ttya}. |
| 11427 | |
| 11428 | @end table |
| 11429 | |
| 11430 | @cindex Nindy |
| 11431 | @cindex i960 |
| 11432 | @dfn{Nindy} is a ROM Monitor program for Intel 960 target systems. When |
| 11433 | @value{GDBN} is configured to control a remote Intel 960 using Nindy, you can |
| 11434 | tell @value{GDBN} how to connect to the 960 in several ways: |
| 11435 | |
| 11436 | @itemize @bullet |
| 11437 | @item |
| 11438 | Through command line options specifying serial port, version of the |
| 11439 | Nindy protocol, and communications speed; |
| 11440 | |
| 11441 | @item |
| 11442 | By responding to a prompt on startup; |
| 11443 | |
| 11444 | @item |
| 11445 | By using the @code{target} command at any point during your @value{GDBN} |
| 11446 | session. @xref{Target Commands, ,Commands for managing targets}. |
| 11447 | |
| 11448 | @end itemize |
| 11449 | |
| 11450 | @cindex download to Nindy-960 |
| 11451 | With the Nindy interface to an Intel 960 board, @code{load} |
| 11452 | downloads @var{filename} to the 960 as well as adding its symbols in |
| 11453 | @value{GDBN}. |
| 11454 | |
| 11455 | @menu |
| 11456 | * Nindy Startup:: Startup with Nindy |
| 11457 | * Nindy Options:: Options for Nindy |
| 11458 | * Nindy Reset:: Nindy reset command |
| 11459 | @end menu |
| 11460 | |
| 11461 | @node Nindy Startup |
| 11462 | @subsubsection Startup with Nindy |
| 11463 | |
| 11464 | If you simply start @code{@value{GDBP}} without using any command-line |
| 11465 | options, you are prompted for what serial port to use, @emph{before} you |
| 11466 | reach the ordinary @value{GDBN} prompt: |
| 11467 | |
| 11468 | @smallexample |
| 11469 | Attach /dev/ttyNN -- specify NN, or "quit" to quit: |
| 11470 | @end smallexample |
| 11471 | |
| 11472 | @noindent |
| 11473 | Respond to the prompt with whatever suffix (after @samp{/dev/tty}) |
| 11474 | identifies the serial port you want to use. You can, if you choose, |
| 11475 | simply start up with no Nindy connection by responding to the prompt |
| 11476 | with an empty line. If you do this and later wish to attach to Nindy, |
| 11477 | use @code{target} (@pxref{Target Commands, ,Commands for managing targets}). |
| 11478 | |
| 11479 | @node Nindy Options |
| 11480 | @subsubsection Options for Nindy |
| 11481 | |
| 11482 | These are the startup options for beginning your @value{GDBN} session with a |
| 11483 | Nindy-960 board attached: |
| 11484 | |
| 11485 | @table @code |
| 11486 | @item -r @var{port} |
| 11487 | Specify the serial port name of a serial interface to be used to connect |
| 11488 | to the target system. This option is only available when @value{GDBN} is |
| 11489 | configured for the Intel 960 target architecture. You may specify |
| 11490 | @var{port} as any of: a full pathname (e.g. @samp{-r /dev/ttya}), a |
| 11491 | device name in @file{/dev} (e.g. @samp{-r ttya}), or simply the unique |
| 11492 | suffix for a specific @code{tty} (e.g. @samp{-r a}). |
| 11493 | |
| 11494 | @item -O |
| 11495 | (An uppercase letter ``O'', not a zero.) Specify that @value{GDBN} should use |
| 11496 | the ``old'' Nindy monitor protocol to connect to the target system. |
| 11497 | This option is only available when @value{GDBN} is configured for the Intel 960 |
| 11498 | target architecture. |
| 11499 | |
| 11500 | @quotation |
| 11501 | @emph{Warning:} if you specify @samp{-O}, but are actually trying to |
| 11502 | connect to a target system that expects the newer protocol, the connection |
| 11503 | fails, appearing to be a speed mismatch. @value{GDBN} repeatedly |
| 11504 | attempts to reconnect at several different line speeds. You can abort |
| 11505 | this process with an interrupt. |
| 11506 | @end quotation |
| 11507 | |
| 11508 | @item -brk |
| 11509 | Specify that @value{GDBN} should first send a @code{BREAK} signal to the target |
| 11510 | system, in an attempt to reset it, before connecting to a Nindy target. |
| 11511 | |
| 11512 | @quotation |
| 11513 | @emph{Warning:} Many target systems do not have the hardware that this |
| 11514 | requires; it only works with a few boards. |
| 11515 | @end quotation |
| 11516 | @end table |
| 11517 | |
| 11518 | The standard @samp{-b} option controls the line speed used on the serial |
| 11519 | port. |
| 11520 | |
| 11521 | @c @group |
| 11522 | @node Nindy Reset |
| 11523 | @subsubsection Nindy reset command |
| 11524 | |
| 11525 | @table @code |
| 11526 | @item reset |
| 11527 | @kindex reset |
| 11528 | For a Nindy target, this command sends a ``break'' to the remote target |
| 11529 | system; this is only useful if the target has been equipped with a |
| 11530 | circuit to perform a hard reset (or some other interesting action) when |
| 11531 | a break is detected. |
| 11532 | @end table |
| 11533 | @c @end group |
| 11534 | |
| 11535 | @node M32R/D |
| 11536 | @subsection Mitsubishi M32R/D |
| 11537 | |
| 11538 | @table @code |
| 11539 | |
| 11540 | @kindex target m32r |
| 11541 | @item target m32r @var{dev} |
| 11542 | Mitsubishi M32R/D ROM monitor. |
| 11543 | |
| 11544 | @end table |
| 11545 | |
| 11546 | @node M68K |
| 11547 | @subsection M68k |
| 11548 | |
| 11549 | The Motorola m68k configuration includes ColdFire support, and |
| 11550 | target command for the following ROM monitors. |
| 11551 | |
| 11552 | @table @code |
| 11553 | |
| 11554 | @kindex target abug |
| 11555 | @item target abug @var{dev} |
| 11556 | ABug ROM monitor for M68K. |
| 11557 | |
| 11558 | @kindex target cpu32bug |
| 11559 | @item target cpu32bug @var{dev} |
| 11560 | CPU32BUG monitor, running on a CPU32 (M68K) board. |
| 11561 | |
| 11562 | @kindex target dbug |
| 11563 | @item target dbug @var{dev} |
| 11564 | dBUG ROM monitor for Motorola ColdFire. |
| 11565 | |
| 11566 | @kindex target est |
| 11567 | @item target est @var{dev} |
| 11568 | EST-300 ICE monitor, running on a CPU32 (M68K) board. |
| 11569 | |
| 11570 | @kindex target rom68k |
| 11571 | @item target rom68k @var{dev} |
| 11572 | ROM 68K monitor, running on an M68K IDP board. |
| 11573 | |
| 11574 | @end table |
| 11575 | |
| 11576 | If @value{GDBN} is configured with @code{m68*-ericsson-*}, it will |
| 11577 | instead have only a single special target command: |
| 11578 | |
| 11579 | @table @code |
| 11580 | |
| 11581 | @kindex target es1800 |
| 11582 | @item target es1800 @var{dev} |
| 11583 | ES-1800 emulator for M68K. |
| 11584 | |
| 11585 | @end table |
| 11586 | |
| 11587 | [context?] |
| 11588 | |
| 11589 | @table @code |
| 11590 | |
| 11591 | @kindex target rombug |
| 11592 | @item target rombug @var{dev} |
| 11593 | ROMBUG ROM monitor for OS/9000. |
| 11594 | |
| 11595 | @end table |
| 11596 | |
| 11597 | @node MIPS Embedded |
| 11598 | @subsection MIPS Embedded |
| 11599 | |
| 11600 | @cindex MIPS boards |
| 11601 | @value{GDBN} can use the MIPS remote debugging protocol to talk to a |
| 11602 | MIPS board attached to a serial line. This is available when |
| 11603 | you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. |
| 11604 | |
| 11605 | @need 1000 |
| 11606 | Use these @value{GDBN} commands to specify the connection to your target board: |
| 11607 | |
| 11608 | @table @code |
| 11609 | @item target mips @var{port} |
| 11610 | @kindex target mips @var{port} |
| 11611 | To run a program on the board, start up @code{@value{GDBP}} with the |
| 11612 | name of your program as the argument. To connect to the board, use the |
| 11613 | command @samp{target mips @var{port}}, where @var{port} is the name of |
| 11614 | the serial port connected to the board. If the program has not already |
| 11615 | been downloaded to the board, you may use the @code{load} command to |
| 11616 | download it. You can then use all the usual @value{GDBN} commands. |
| 11617 | |
| 11618 | For example, this sequence connects to the target board through a serial |
| 11619 | port, and loads and runs a program called @var{prog} through the |
| 11620 | debugger: |
| 11621 | |
| 11622 | @smallexample |
| 11623 | host$ @value{GDBP} @var{prog} |
| 11624 | @value{GDBN} is free software and @dots{} |
| 11625 | (@value{GDBP}) target mips /dev/ttyb |
| 11626 | (@value{GDBP}) load @var{prog} |
| 11627 | (@value{GDBP}) run |
| 11628 | @end smallexample |
| 11629 | |
| 11630 | @item target mips @var{hostname}:@var{portnumber} |
| 11631 | On some @value{GDBN} host configurations, you can specify a TCP |
| 11632 | connection (for instance, to a serial line managed by a terminal |
| 11633 | concentrator) instead of a serial port, using the syntax |
| 11634 | @samp{@var{hostname}:@var{portnumber}}. |
| 11635 | |
| 11636 | @item target pmon @var{port} |
| 11637 | @kindex target pmon @var{port} |
| 11638 | PMON ROM monitor. |
| 11639 | |
| 11640 | @item target ddb @var{port} |
| 11641 | @kindex target ddb @var{port} |
| 11642 | NEC's DDB variant of PMON for Vr4300. |
| 11643 | |
| 11644 | @item target lsi @var{port} |
| 11645 | @kindex target lsi @var{port} |
| 11646 | LSI variant of PMON. |
| 11647 | |
| 11648 | @kindex target r3900 |
| 11649 | @item target r3900 @var{dev} |
| 11650 | Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips. |
| 11651 | |
| 11652 | @kindex target array |
| 11653 | @item target array @var{dev} |
| 11654 | Array Tech LSI33K RAID controller board. |
| 11655 | |
| 11656 | @end table |
| 11657 | |
| 11658 | |
| 11659 | @noindent |
| 11660 | @value{GDBN} also supports these special commands for MIPS targets: |
| 11661 | |
| 11662 | @table @code |
| 11663 | @item set processor @var{args} |
| 11664 | @itemx show processor |
| 11665 | @kindex set processor @var{args} |
| 11666 | @kindex show processor |
| 11667 | Use the @code{set processor} command to set the type of MIPS |
| 11668 | processor when you want to access processor-type-specific registers. |
| 11669 | For example, @code{set processor @var{r3041}} tells @value{GDBN} |
| 11670 | to use the CPU registers appropriate for the 3041 chip. |
| 11671 | Use the @code{show processor} command to see what MIPS processor @value{GDBN} |
| 11672 | is using. Use the @code{info reg} command to see what registers |
| 11673 | @value{GDBN} is using. |
| 11674 | |
| 11675 | @item set mipsfpu double |
| 11676 | @itemx set mipsfpu single |
| 11677 | @itemx set mipsfpu none |
| 11678 | @itemx show mipsfpu |
| 11679 | @kindex set mipsfpu |
| 11680 | @kindex show mipsfpu |
| 11681 | @cindex MIPS remote floating point |
| 11682 | @cindex floating point, MIPS remote |
| 11683 | If your target board does not support the MIPS floating point |
| 11684 | coprocessor, you should use the command @samp{set mipsfpu none} (if you |
| 11685 | need this, you may wish to put the command in your @value{GDBN} init |
| 11686 | file). This tells @value{GDBN} how to find the return value of |
| 11687 | functions which return floating point values. It also allows |
| 11688 | @value{GDBN} to avoid saving the floating point registers when calling |
| 11689 | functions on the board. If you are using a floating point coprocessor |
| 11690 | with only single precision floating point support, as on the @sc{r4650} |
| 11691 | processor, use the command @samp{set mipsfpu single}. The default |
| 11692 | double precision floating point coprocessor may be selected using |
| 11693 | @samp{set mipsfpu double}. |
| 11694 | |
| 11695 | In previous versions the only choices were double precision or no |
| 11696 | floating point, so @samp{set mipsfpu on} will select double precision |
| 11697 | and @samp{set mipsfpu off} will select no floating point. |
| 11698 | |
| 11699 | As usual, you can inquire about the @code{mipsfpu} variable with |
| 11700 | @samp{show mipsfpu}. |
| 11701 | |
| 11702 | @item set remotedebug @var{n} |
| 11703 | @itemx show remotedebug |
| 11704 | @kindex set remotedebug@r{, MIPS protocol} |
| 11705 | @kindex show remotedebug@r{, MIPS protocol} |
| 11706 | @cindex @code{remotedebug}, MIPS protocol |
| 11707 | @cindex MIPS @code{remotedebug} protocol |
| 11708 | @c FIXME! For this to be useful, you must know something about the MIPS |
| 11709 | @c FIXME...protocol. Where is it described? |
| 11710 | You can see some debugging information about communications with the board |
| 11711 | by setting the @code{remotedebug} variable. If you set it to @code{1} using |
| 11712 | @samp{set remotedebug 1}, every packet is displayed. If you set it |
| 11713 | to @code{2}, every character is displayed. You can check the current value |
| 11714 | at any time with the command @samp{show remotedebug}. |
| 11715 | |
| 11716 | @item set timeout @var{seconds} |
| 11717 | @itemx set retransmit-timeout @var{seconds} |
| 11718 | @itemx show timeout |
| 11719 | @itemx show retransmit-timeout |
| 11720 | @cindex @code{timeout}, MIPS protocol |
| 11721 | @cindex @code{retransmit-timeout}, MIPS protocol |
| 11722 | @kindex set timeout |
| 11723 | @kindex show timeout |
| 11724 | @kindex set retransmit-timeout |
| 11725 | @kindex show retransmit-timeout |
| 11726 | You can control the timeout used while waiting for a packet, in the MIPS |
| 11727 | remote protocol, with the @code{set timeout @var{seconds}} command. The |
| 11728 | default is 5 seconds. Similarly, you can control the timeout used while |
| 11729 | waiting for an acknowledgement of a packet with the @code{set |
| 11730 | retransmit-timeout @var{seconds}} command. The default is 3 seconds. |
| 11731 | You can inspect both values with @code{show timeout} and @code{show |
| 11732 | retransmit-timeout}. (These commands are @emph{only} available when |
| 11733 | @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) |
| 11734 | |
| 11735 | The timeout set by @code{set timeout} does not apply when @value{GDBN} |
| 11736 | is waiting for your program to stop. In that case, @value{GDBN} waits |
| 11737 | forever because it has no way of knowing how long the program is going |
| 11738 | to run before stopping. |
| 11739 | @end table |
| 11740 | |
| 11741 | @node OpenRISC 1000 |
| 11742 | @subsection OpenRISC 1000 |
| 11743 | @cindex OpenRISC 1000 |
| 11744 | |
| 11745 | @cindex or1k boards |
| 11746 | See OR1k Architecture document (@uref{www.opencores.org}) for more information |
| 11747 | about platform and commands. |
| 11748 | |
| 11749 | @table @code |
| 11750 | |
| 11751 | @kindex target jtag |
| 11752 | @item target jtag jtag://@var{host}:@var{port} |
| 11753 | |
| 11754 | Connects to remote JTAG server. |
| 11755 | JTAG remote server can be either an or1ksim or JTAG server, |
| 11756 | connected via parallel port to the board. |
| 11757 | |
| 11758 | Example: @code{target jtag jtag://localhost:9999} |
| 11759 | |
| 11760 | @kindex or1ksim |
| 11761 | @item or1ksim @var{command} |
| 11762 | If connected to @code{or1ksim} OpenRISC 1000 Architectural |
| 11763 | Simulator, proprietary commands can be executed. |
| 11764 | |
| 11765 | @kindex info or1k spr |
| 11766 | @item info or1k spr |
| 11767 | Displays spr groups. |
| 11768 | |
| 11769 | @item info or1k spr @var{group} |
| 11770 | @itemx info or1k spr @var{groupno} |
| 11771 | Displays register names in selected group. |
| 11772 | |
| 11773 | @item info or1k spr @var{group} @var{register} |
| 11774 | @itemx info or1k spr @var{register} |
| 11775 | @itemx info or1k spr @var{groupno} @var{registerno} |
| 11776 | @itemx info or1k spr @var{registerno} |
| 11777 | Shows information about specified spr register. |
| 11778 | |
| 11779 | @kindex spr |
| 11780 | @item spr @var{group} @var{register} @var{value} |
| 11781 | @itemx spr @var{register @var{value}} |
| 11782 | @itemx spr @var{groupno} @var{registerno @var{value}} |
| 11783 | @itemx spr @var{registerno @var{value}} |
| 11784 | Writes @var{value} to specified spr register. |
| 11785 | @end table |
| 11786 | |
| 11787 | Some implementations of OpenRISC 1000 Architecture also have hardware trace. |
| 11788 | It is very similar to @value{GDBN} trace, except it does not interfere with normal |
| 11789 | program execution and is thus much faster. Hardware breakpoints/watchpoint |
| 11790 | triggers can be set using: |
| 11791 | @table @code |
| 11792 | @item $LEA/$LDATA |
| 11793 | Load effective address/data |
| 11794 | @item $SEA/$SDATA |
| 11795 | Store effective address/data |
| 11796 | @item $AEA/$ADATA |
| 11797 | Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA) |
| 11798 | @item $FETCH |
| 11799 | Fetch data |
| 11800 | @end table |
| 11801 | |
| 11802 | When triggered, it can capture low level data, like: @code{PC}, @code{LSEA}, |
| 11803 | @code{LDATA}, @code{SDATA}, @code{READSPR}, @code{WRITESPR}, @code{INSTR}. |
| 11804 | |
| 11805 | @code{htrace} commands: |
| 11806 | @cindex OpenRISC 1000 htrace |
| 11807 | @table @code |
| 11808 | @kindex hwatch |
| 11809 | @item hwatch @var{conditional} |
| 11810 | Set hardware watchpoint on combination of Load/Store Effecive Address(es) |
| 11811 | or Data. For example: |
| 11812 | |
| 11813 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} |
| 11814 | |
| 11815 | @code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)} |
| 11816 | |
| 11817 | @kindex htrace info |
| 11818 | @item htrace info |
| 11819 | Display information about current HW trace configuration. |
| 11820 | |
| 11821 | @kindex htrace trigger |
| 11822 | @item htrace trigger @var{conditional} |
| 11823 | Set starting criteria for HW trace. |
| 11824 | |
| 11825 | @kindex htrace qualifier |
| 11826 | @item htrace qualifier @var{conditional} |
| 11827 | Set acquisition qualifier for HW trace. |
| 11828 | |
| 11829 | @kindex htrace stop |
| 11830 | @item htrace stop @var{conditional} |
| 11831 | Set HW trace stopping criteria. |
| 11832 | |
| 11833 | @kindex htrace record |
| 11834 | @item htrace record @var{[data]*} |
| 11835 | Selects the data to be recorded, when qualifier is met and HW trace was |
| 11836 | triggered. |
| 11837 | |
| 11838 | @kindex htrace enable |
| 11839 | @item htrace enable |
| 11840 | @kindex htrace disable |
| 11841 | @itemx htrace disable |
| 11842 | Enables/disables the HW trace. |
| 11843 | |
| 11844 | @kindex htrace rewind |
| 11845 | @item htrace rewind @var{[filename]} |
| 11846 | Clears currently recorded trace data. |
| 11847 | |
| 11848 | If filename is specified, new trace file is made and any newly collected data |
| 11849 | will be written there. |
| 11850 | |
| 11851 | @kindex htrace print |
| 11852 | @item htrace print @var{[start [len]]} |
| 11853 | Prints trace buffer, using current record configuration. |
| 11854 | |
| 11855 | @kindex htrace mode continuous |
| 11856 | @item htrace mode continuous |
| 11857 | Set continuous trace mode. |
| 11858 | |
| 11859 | @kindex htrace mode suspend |
| 11860 | @item htrace mode suspend |
| 11861 | Set suspend trace mode. |
| 11862 | |
| 11863 | @end table |
| 11864 | |
| 11865 | @node PowerPC |
| 11866 | @subsection PowerPC |
| 11867 | |
| 11868 | @table @code |
| 11869 | |
| 11870 | @kindex target dink32 |
| 11871 | @item target dink32 @var{dev} |
| 11872 | DINK32 ROM monitor. |
| 11873 | |
| 11874 | @kindex target ppcbug |
| 11875 | @item target ppcbug @var{dev} |
| 11876 | @kindex target ppcbug1 |
| 11877 | @item target ppcbug1 @var{dev} |
| 11878 | PPCBUG ROM monitor for PowerPC. |
| 11879 | |
| 11880 | @kindex target sds |
| 11881 | @item target sds @var{dev} |
| 11882 | SDS monitor, running on a PowerPC board (such as Motorola's ADS). |
| 11883 | |
| 11884 | @end table |
| 11885 | |
| 11886 | @node PA |
| 11887 | @subsection HP PA Embedded |
| 11888 | |
| 11889 | @table @code |
| 11890 | |
| 11891 | @kindex target op50n |
| 11892 | @item target op50n @var{dev} |
| 11893 | OP50N monitor, running on an OKI HPPA board. |
| 11894 | |
| 11895 | @kindex target w89k |
| 11896 | @item target w89k @var{dev} |
| 11897 | W89K monitor, running on a Winbond HPPA board. |
| 11898 | |
| 11899 | @end table |
| 11900 | |
| 11901 | @node SH |
| 11902 | @subsection Hitachi SH |
| 11903 | |
| 11904 | @table @code |
| 11905 | |
| 11906 | @kindex target hms@r{, with Hitachi SH} |
| 11907 | @item target hms @var{dev} |
| 11908 | A Hitachi SH board attached via serial line to your host. Use special |
| 11909 | commands @code{device} and @code{speed} to control the serial line and |
| 11910 | the communications speed used. |
| 11911 | |
| 11912 | @kindex target e7000@r{, with Hitachi SH} |
| 11913 | @item target e7000 @var{dev} |
| 11914 | E7000 emulator for Hitachi SH. |
| 11915 | |
| 11916 | @kindex target sh3@r{, with SH} |
| 11917 | @kindex target sh3e@r{, with SH} |
| 11918 | @item target sh3 @var{dev} |
| 11919 | @item target sh3e @var{dev} |
| 11920 | Hitachi SH-3 and SH-3E target systems. |
| 11921 | |
| 11922 | @end table |
| 11923 | |
| 11924 | @node Sparclet |
| 11925 | @subsection Tsqware Sparclet |
| 11926 | |
| 11927 | @cindex Sparclet |
| 11928 | |
| 11929 | @value{GDBN} enables developers to debug tasks running on |
| 11930 | Sparclet targets from a Unix host. |
| 11931 | @value{GDBN} uses code that runs on |
| 11932 | both the Unix host and on the Sparclet target. The program |
| 11933 | @code{@value{GDBP}} is installed and executed on the Unix host. |
| 11934 | |
| 11935 | @table @code |
| 11936 | @item remotetimeout @var{args} |
| 11937 | @kindex remotetimeout |
| 11938 | @value{GDBN} supports the option @code{remotetimeout}. |
| 11939 | This option is set by the user, and @var{args} represents the number of |
| 11940 | seconds @value{GDBN} waits for responses. |
| 11941 | @end table |
| 11942 | |
| 11943 | @cindex compiling, on Sparclet |
| 11944 | When compiling for debugging, include the options @samp{-g} to get debug |
| 11945 | information and @samp{-Ttext} to relocate the program to where you wish to |
| 11946 | load it on the target. You may also want to add the options @samp{-n} or |
| 11947 | @samp{-N} in order to reduce the size of the sections. Example: |
| 11948 | |
| 11949 | @smallexample |
| 11950 | sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N |
| 11951 | @end smallexample |
| 11952 | |
| 11953 | You can use @code{objdump} to verify that the addresses are what you intended: |
| 11954 | |
| 11955 | @smallexample |
| 11956 | sparclet-aout-objdump --headers --syms prog |
| 11957 | @end smallexample |
| 11958 | |
| 11959 | @cindex running, on Sparclet |
| 11960 | Once you have set |
| 11961 | your Unix execution search path to find @value{GDBN}, you are ready to |
| 11962 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} |
| 11963 | (or @code{sparclet-aout-gdb}, depending on your installation). |
| 11964 | |
| 11965 | @value{GDBN} comes up showing the prompt: |
| 11966 | |
| 11967 | @smallexample |
| 11968 | (gdbslet) |
| 11969 | @end smallexample |
| 11970 | |
| 11971 | @menu |
| 11972 | * Sparclet File:: Setting the file to debug |
| 11973 | * Sparclet Connection:: Connecting to Sparclet |
| 11974 | * Sparclet Download:: Sparclet download |
| 11975 | * Sparclet Execution:: Running and debugging |
| 11976 | @end menu |
| 11977 | |
| 11978 | @node Sparclet File |
| 11979 | @subsubsection Setting file to debug |
| 11980 | |
| 11981 | The @value{GDBN} command @code{file} lets you choose with program to debug. |
| 11982 | |
| 11983 | @smallexample |
| 11984 | (gdbslet) file prog |
| 11985 | @end smallexample |
| 11986 | |
| 11987 | @need 1000 |
| 11988 | @value{GDBN} then attempts to read the symbol table of @file{prog}. |
| 11989 | @value{GDBN} locates |
| 11990 | the file by searching the directories listed in the command search |
| 11991 | path. |
| 11992 | If the file was compiled with debug information (option "-g"), source |
| 11993 | files will be searched as well. |
| 11994 | @value{GDBN} locates |
| 11995 | the source files by searching the directories listed in the directory search |
| 11996 | path (@pxref{Environment, ,Your program's environment}). |
| 11997 | If it fails |
| 11998 | to find a file, it displays a message such as: |
| 11999 | |
| 12000 | @smallexample |
| 12001 | prog: No such file or directory. |
| 12002 | @end smallexample |
| 12003 | |
| 12004 | When this happens, add the appropriate directories to the search paths with |
| 12005 | the @value{GDBN} commands @code{path} and @code{dir}, and execute the |
| 12006 | @code{target} command again. |
| 12007 | |
| 12008 | @node Sparclet Connection |
| 12009 | @subsubsection Connecting to Sparclet |
| 12010 | |
| 12011 | The @value{GDBN} command @code{target} lets you connect to a Sparclet target. |
| 12012 | To connect to a target on serial port ``@code{ttya}'', type: |
| 12013 | |
| 12014 | @smallexample |
| 12015 | (gdbslet) target sparclet /dev/ttya |
| 12016 | Remote target sparclet connected to /dev/ttya |
| 12017 | main () at ../prog.c:3 |
| 12018 | @end smallexample |
| 12019 | |
| 12020 | @need 750 |
| 12021 | @value{GDBN} displays messages like these: |
| 12022 | |
| 12023 | @smallexample |
| 12024 | Connected to ttya. |
| 12025 | @end smallexample |
| 12026 | |
| 12027 | @node Sparclet Download |
| 12028 | @subsubsection Sparclet download |
| 12029 | |
| 12030 | @cindex download to Sparclet |
| 12031 | Once connected to the Sparclet target, |
| 12032 | you can use the @value{GDBN} |
| 12033 | @code{load} command to download the file from the host to the target. |
| 12034 | The file name and load offset should be given as arguments to the @code{load} |
| 12035 | command. |
| 12036 | Since the file format is aout, the program must be loaded to the starting |
| 12037 | address. You can use @code{objdump} to find out what this value is. The load |
| 12038 | offset is an offset which is added to the VMA (virtual memory address) |
| 12039 | of each of the file's sections. |
| 12040 | For instance, if the program |
| 12041 | @file{prog} was linked to text address 0x1201000, with data at 0x12010160 |
| 12042 | and bss at 0x12010170, in @value{GDBN}, type: |
| 12043 | |
| 12044 | @smallexample |
| 12045 | (gdbslet) load prog 0x12010000 |
| 12046 | Loading section .text, size 0xdb0 vma 0x12010000 |
| 12047 | @end smallexample |
| 12048 | |
| 12049 | If the code is loaded at a different address then what the program was linked |
| 12050 | to, you may need to use the @code{section} and @code{add-symbol-file} commands |
| 12051 | to tell @value{GDBN} where to map the symbol table. |
| 12052 | |
| 12053 | @node Sparclet Execution |
| 12054 | @subsubsection Running and debugging |
| 12055 | |
| 12056 | @cindex running and debugging Sparclet programs |
| 12057 | You can now begin debugging the task using @value{GDBN}'s execution control |
| 12058 | commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN} |
| 12059 | manual for the list of commands. |
| 12060 | |
| 12061 | @smallexample |
| 12062 | (gdbslet) b main |
| 12063 | Breakpoint 1 at 0x12010000: file prog.c, line 3. |
| 12064 | (gdbslet) run |
| 12065 | Starting program: prog |
| 12066 | Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3 |
| 12067 | 3 char *symarg = 0; |
| 12068 | (gdbslet) step |
| 12069 | 4 char *execarg = "hello!"; |
| 12070 | (gdbslet) |
| 12071 | @end smallexample |
| 12072 | |
| 12073 | @node Sparclite |
| 12074 | @subsection Fujitsu Sparclite |
| 12075 | |
| 12076 | @table @code |
| 12077 | |
| 12078 | @kindex target sparclite |
| 12079 | @item target sparclite @var{dev} |
| 12080 | Fujitsu sparclite boards, used only for the purpose of loading. |
| 12081 | You must use an additional command to debug the program. |
| 12082 | For example: target remote @var{dev} using @value{GDBN} standard |
| 12083 | remote protocol. |
| 12084 | |
| 12085 | @end table |
| 12086 | |
| 12087 | @node ST2000 |
| 12088 | @subsection Tandem ST2000 |
| 12089 | |
| 12090 | @value{GDBN} may be used with a Tandem ST2000 phone switch, running Tandem's |
| 12091 | STDBUG protocol. |
| 12092 | |
| 12093 | To connect your ST2000 to the host system, see the manufacturer's |
| 12094 | manual. Once the ST2000 is physically attached, you can run: |
| 12095 | |
| 12096 | @smallexample |
| 12097 | target st2000 @var{dev} @var{speed} |
| 12098 | @end smallexample |
| 12099 | |
| 12100 | @noindent |
| 12101 | to establish it as your debugging environment. @var{dev} is normally |
| 12102 | the name of a serial device, such as @file{/dev/ttya}, connected to the |
| 12103 | ST2000 via a serial line. You can instead specify @var{dev} as a TCP |
| 12104 | connection (for example, to a serial line attached via a terminal |
| 12105 | concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}. |
| 12106 | |
| 12107 | The @code{load} and @code{attach} commands are @emph{not} defined for |
| 12108 | this target; you must load your program into the ST2000 as you normally |
| 12109 | would for standalone operation. @value{GDBN} reads debugging information |
| 12110 | (such as symbols) from a separate, debugging version of the program |
| 12111 | available on your host computer. |
| 12112 | @c FIXME!! This is terribly vague; what little content is here is |
| 12113 | @c basically hearsay. |
| 12114 | |
| 12115 | @cindex ST2000 auxiliary commands |
| 12116 | These auxiliary @value{GDBN} commands are available to help you with the ST2000 |
| 12117 | environment: |
| 12118 | |
| 12119 | @table @code |
| 12120 | @item st2000 @var{command} |
| 12121 | @kindex st2000 @var{cmd} |
| 12122 | @cindex STDBUG commands (ST2000) |
| 12123 | @cindex commands to STDBUG (ST2000) |
| 12124 | Send a @var{command} to the STDBUG monitor. See the manufacturer's |
| 12125 | manual for available commands. |
| 12126 | |
| 12127 | @item connect |
| 12128 | @cindex connect (to STDBUG) |
| 12129 | Connect the controlling terminal to the STDBUG command monitor. When |
| 12130 | you are done interacting with STDBUG, typing either of two character |
| 12131 | sequences gets you back to the @value{GDBN} command prompt: |
| 12132 | @kbd{@key{RET}~.} (Return, followed by tilde and period) or |
| 12133 | @kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D). |
| 12134 | @end table |
| 12135 | |
| 12136 | @node Z8000 |
| 12137 | @subsection Zilog Z8000 |
| 12138 | |
| 12139 | @cindex Z8000 |
| 12140 | @cindex simulator, Z8000 |
| 12141 | @cindex Zilog Z8000 simulator |
| 12142 | |
| 12143 | When configured for debugging Zilog Z8000 targets, @value{GDBN} includes |
| 12144 | a Z8000 simulator. |
| 12145 | |
| 12146 | For the Z8000 family, @samp{target sim} simulates either the Z8002 (the |
| 12147 | unsegmented variant of the Z8000 architecture) or the Z8001 (the |
| 12148 | segmented variant). The simulator recognizes which architecture is |
| 12149 | appropriate by inspecting the object code. |
| 12150 | |
| 12151 | @table @code |
| 12152 | @item target sim @var{args} |
| 12153 | @kindex sim |
| 12154 | @kindex target sim@r{, with Z8000} |
| 12155 | Debug programs on a simulated CPU. If the simulator supports setup |
| 12156 | options, specify them via @var{args}. |
| 12157 | @end table |
| 12158 | |
| 12159 | @noindent |
| 12160 | After specifying this target, you can debug programs for the simulated |
| 12161 | CPU in the same style as programs for your host computer; use the |
| 12162 | @code{file} command to load a new program image, the @code{run} command |
| 12163 | to run your program, and so on. |
| 12164 | |
| 12165 | As well as making available all the usual machine registers |
| 12166 | (@pxref{Registers, ,Registers}), the Z8000 simulator provides three |
| 12167 | additional items of information as specially named registers: |
| 12168 | |
| 12169 | @table @code |
| 12170 | |
| 12171 | @item cycles |
| 12172 | Counts clock-ticks in the simulator. |
| 12173 | |
| 12174 | @item insts |
| 12175 | Counts instructions run in the simulator. |
| 12176 | |
| 12177 | @item time |
| 12178 | Execution time in 60ths of a second. |
| 12179 | |
| 12180 | @end table |
| 12181 | |
| 12182 | You can refer to these values in @value{GDBN} expressions with the usual |
| 12183 | conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a |
| 12184 | conditional breakpoint that suspends only after at least 5000 |
| 12185 | simulated clock ticks. |
| 12186 | |
| 12187 | @node Architectures |
| 12188 | @section Architectures |
| 12189 | |
| 12190 | This section describes characteristics of architectures that affect |
| 12191 | all uses of @value{GDBN} with the architecture, both native and cross. |
| 12192 | |
| 12193 | @menu |
| 12194 | * A29K:: |
| 12195 | * Alpha:: |
| 12196 | * MIPS:: |
| 12197 | @end menu |
| 12198 | |
| 12199 | @node A29K |
| 12200 | @subsection A29K |
| 12201 | |
| 12202 | @table @code |
| 12203 | |
| 12204 | @kindex set rstack_high_address |
| 12205 | @cindex AMD 29K register stack |
| 12206 | @cindex register stack, AMD29K |
| 12207 | @item set rstack_high_address @var{address} |
| 12208 | On AMD 29000 family processors, registers are saved in a separate |
| 12209 | @dfn{register stack}. There is no way for @value{GDBN} to determine the |
| 12210 | extent of this stack. Normally, @value{GDBN} just assumes that the |
| 12211 | stack is ``large enough''. This may result in @value{GDBN} referencing |
| 12212 | memory locations that do not exist. If necessary, you can get around |
| 12213 | this problem by specifying the ending address of the register stack with |
| 12214 | the @code{set rstack_high_address} command. The argument should be an |
| 12215 | address, which you probably want to precede with @samp{0x} to specify in |
| 12216 | hexadecimal. |
| 12217 | |
| 12218 | @kindex show rstack_high_address |
| 12219 | @item show rstack_high_address |
| 12220 | Display the current limit of the register stack, on AMD 29000 family |
| 12221 | processors. |
| 12222 | |
| 12223 | @end table |
| 12224 | |
| 12225 | @node Alpha |
| 12226 | @subsection Alpha |
| 12227 | |
| 12228 | See the following section. |
| 12229 | |
| 12230 | @node MIPS |
| 12231 | @subsection MIPS |
| 12232 | |
| 12233 | @cindex stack on Alpha |
| 12234 | @cindex stack on MIPS |
| 12235 | @cindex Alpha stack |
| 12236 | @cindex MIPS stack |
| 12237 | Alpha- and MIPS-based computers use an unusual stack frame, which |
| 12238 | sometimes requires @value{GDBN} to search backward in the object code to |
| 12239 | find the beginning of a function. |
| 12240 | |
| 12241 | @cindex response time, MIPS debugging |
| 12242 | To improve response time (especially for embedded applications, where |
| 12243 | @value{GDBN} may be restricted to a slow serial line for this search) |
| 12244 | you may want to limit the size of this search, using one of these |
| 12245 | commands: |
| 12246 | |
| 12247 | @table @code |
| 12248 | @cindex @code{heuristic-fence-post} (Alpha, MIPS) |
| 12249 | @item set heuristic-fence-post @var{limit} |
| 12250 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its |
| 12251 | search for the beginning of a function. A value of @var{0} (the |
| 12252 | default) means there is no limit. However, except for @var{0}, the |
| 12253 | larger the limit the more bytes @code{heuristic-fence-post} must search |
| 12254 | and therefore the longer it takes to run. |
| 12255 | |
| 12256 | @item show heuristic-fence-post |
| 12257 | Display the current limit. |
| 12258 | @end table |
| 12259 | |
| 12260 | @noindent |
| 12261 | These commands are available @emph{only} when @value{GDBN} is configured |
| 12262 | for debugging programs on Alpha or MIPS processors. |
| 12263 | |
| 12264 | |
| 12265 | @node Controlling GDB |
| 12266 | @chapter Controlling @value{GDBN} |
| 12267 | |
| 12268 | You can alter the way @value{GDBN} interacts with you by using the |
| 12269 | @code{set} command. For commands controlling how @value{GDBN} displays |
| 12270 | data, see @ref{Print Settings, ,Print settings}. Other settings are |
| 12271 | described here. |
| 12272 | |
| 12273 | @menu |
| 12274 | * Prompt:: Prompt |
| 12275 | * Editing:: Command editing |
| 12276 | * History:: Command history |
| 12277 | * Screen Size:: Screen size |
| 12278 | * Numbers:: Numbers |
| 12279 | * ABI:: Configuring the current ABI |
| 12280 | * Messages/Warnings:: Optional warnings and messages |
| 12281 | * Debugging Output:: Optional messages about internal happenings |
| 12282 | @end menu |
| 12283 | |
| 12284 | @node Prompt |
| 12285 | @section Prompt |
| 12286 | |
| 12287 | @cindex prompt |
| 12288 | |
| 12289 | @value{GDBN} indicates its readiness to read a command by printing a string |
| 12290 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You |
| 12291 | can change the prompt string with the @code{set prompt} command. For |
| 12292 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change |
| 12293 | the prompt in one of the @value{GDBN} sessions so that you can always tell |
| 12294 | which one you are talking to. |
| 12295 | |
| 12296 | @emph{Note:} @code{set prompt} does not add a space for you after the |
| 12297 | prompt you set. This allows you to set a prompt which ends in a space |
| 12298 | or a prompt that does not. |
| 12299 | |
| 12300 | @table @code |
| 12301 | @kindex set prompt |
| 12302 | @item set prompt @var{newprompt} |
| 12303 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. |
| 12304 | |
| 12305 | @kindex show prompt |
| 12306 | @item show prompt |
| 12307 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} |
| 12308 | @end table |
| 12309 | |
| 12310 | @node Editing |
| 12311 | @section Command editing |
| 12312 | @cindex readline |
| 12313 | @cindex command line editing |
| 12314 | |
| 12315 | @value{GDBN} reads its input commands via the @dfn{readline} interface. This |
| 12316 | @sc{gnu} library provides consistent behavior for programs which provide a |
| 12317 | command line interface to the user. Advantages are @sc{gnu} Emacs-style |
| 12318 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history |
| 12319 | substitution, and a storage and recall of command history across |
| 12320 | debugging sessions. |
| 12321 | |
| 12322 | You may control the behavior of command line editing in @value{GDBN} with the |
| 12323 | command @code{set}. |
| 12324 | |
| 12325 | @table @code |
| 12326 | @kindex set editing |
| 12327 | @cindex editing |
| 12328 | @item set editing |
| 12329 | @itemx set editing on |
| 12330 | Enable command line editing (enabled by default). |
| 12331 | |
| 12332 | @item set editing off |
| 12333 | Disable command line editing. |
| 12334 | |
| 12335 | @kindex show editing |
| 12336 | @item show editing |
| 12337 | Show whether command line editing is enabled. |
| 12338 | @end table |
| 12339 | |
| 12340 | @node History |
| 12341 | @section Command history |
| 12342 | |
| 12343 | @value{GDBN} can keep track of the commands you type during your |
| 12344 | debugging sessions, so that you can be certain of precisely what |
| 12345 | happened. Use these commands to manage the @value{GDBN} command |
| 12346 | history facility. |
| 12347 | |
| 12348 | @table @code |
| 12349 | @cindex history substitution |
| 12350 | @cindex history file |
| 12351 | @kindex set history filename |
| 12352 | @kindex GDBHISTFILE |
| 12353 | @item set history filename @var{fname} |
| 12354 | Set the name of the @value{GDBN} command history file to @var{fname}. |
| 12355 | This is the file where @value{GDBN} reads an initial command history |
| 12356 | list, and where it writes the command history from this session when it |
| 12357 | exits. You can access this list through history expansion or through |
| 12358 | the history command editing characters listed below. This file defaults |
| 12359 | to the value of the environment variable @code{GDBHISTFILE}, or to |
| 12360 | @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable |
| 12361 | is not set. |
| 12362 | |
| 12363 | @cindex history save |
| 12364 | @kindex set history save |
| 12365 | @item set history save |
| 12366 | @itemx set history save on |
| 12367 | Record command history in a file, whose name may be specified with the |
| 12368 | @code{set history filename} command. By default, this option is disabled. |
| 12369 | |
| 12370 | @item set history save off |
| 12371 | Stop recording command history in a file. |
| 12372 | |
| 12373 | @cindex history size |
| 12374 | @kindex set history size |
| 12375 | @item set history size @var{size} |
| 12376 | Set the number of commands which @value{GDBN} keeps in its history list. |
| 12377 | This defaults to the value of the environment variable |
| 12378 | @code{HISTSIZE}, or to 256 if this variable is not set. |
| 12379 | @end table |
| 12380 | |
| 12381 | @cindex history expansion |
| 12382 | History expansion assigns special meaning to the character @kbd{!}. |
| 12383 | @ifset have-readline-appendices |
| 12384 | @xref{Event Designators}. |
| 12385 | @end ifset |
| 12386 | |
| 12387 | Since @kbd{!} is also the logical not operator in C, history expansion |
| 12388 | is off by default. If you decide to enable history expansion with the |
| 12389 | @code{set history expansion on} command, you may sometimes need to |
| 12390 | follow @kbd{!} (when it is used as logical not, in an expression) with |
| 12391 | a space or a tab to prevent it from being expanded. The readline |
| 12392 | history facilities do not attempt substitution on the strings |
| 12393 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. |
| 12394 | |
| 12395 | The commands to control history expansion are: |
| 12396 | |
| 12397 | @table @code |
| 12398 | @kindex set history expansion |
| 12399 | @item set history expansion on |
| 12400 | @itemx set history expansion |
| 12401 | Enable history expansion. History expansion is off by default. |
| 12402 | |
| 12403 | @item set history expansion off |
| 12404 | Disable history expansion. |
| 12405 | |
| 12406 | The readline code comes with more complete documentation of |
| 12407 | editing and history expansion features. Users unfamiliar with @sc{gnu} Emacs |
| 12408 | or @code{vi} may wish to read it. |
| 12409 | @ifset have-readline-appendices |
| 12410 | @xref{Command Line Editing}. |
| 12411 | @end ifset |
| 12412 | |
| 12413 | @c @group |
| 12414 | @kindex show history |
| 12415 | @item show history |
| 12416 | @itemx show history filename |
| 12417 | @itemx show history save |
| 12418 | @itemx show history size |
| 12419 | @itemx show history expansion |
| 12420 | These commands display the state of the @value{GDBN} history parameters. |
| 12421 | @code{show history} by itself displays all four states. |
| 12422 | @c @end group |
| 12423 | @end table |
| 12424 | |
| 12425 | @table @code |
| 12426 | @kindex shows |
| 12427 | @item show commands |
| 12428 | Display the last ten commands in the command history. |
| 12429 | |
| 12430 | @item show commands @var{n} |
| 12431 | Print ten commands centered on command number @var{n}. |
| 12432 | |
| 12433 | @item show commands + |
| 12434 | Print ten commands just after the commands last printed. |
| 12435 | @end table |
| 12436 | |
| 12437 | @node Screen Size |
| 12438 | @section Screen size |
| 12439 | @cindex size of screen |
| 12440 | @cindex pauses in output |
| 12441 | |
| 12442 | Certain commands to @value{GDBN} may produce large amounts of |
| 12443 | information output to the screen. To help you read all of it, |
| 12444 | @value{GDBN} pauses and asks you for input at the end of each page of |
| 12445 | output. Type @key{RET} when you want to continue the output, or @kbd{q} |
| 12446 | to discard the remaining output. Also, the screen width setting |
| 12447 | determines when to wrap lines of output. Depending on what is being |
| 12448 | printed, @value{GDBN} tries to break the line at a readable place, |
| 12449 | rather than simply letting it overflow onto the following line. |
| 12450 | |
| 12451 | Normally @value{GDBN} knows the size of the screen from the terminal |
| 12452 | driver software. For example, on Unix @value{GDBN} uses the termcap data base |
| 12453 | together with the value of the @code{TERM} environment variable and the |
| 12454 | @code{stty rows} and @code{stty cols} settings. If this is not correct, |
| 12455 | you can override it with the @code{set height} and @code{set |
| 12456 | width} commands: |
| 12457 | |
| 12458 | @table @code |
| 12459 | @kindex set height |
| 12460 | @kindex set width |
| 12461 | @kindex show width |
| 12462 | @kindex show height |
| 12463 | @item set height @var{lpp} |
| 12464 | @itemx show height |
| 12465 | @itemx set width @var{cpl} |
| 12466 | @itemx show width |
| 12467 | These @code{set} commands specify a screen height of @var{lpp} lines and |
| 12468 | a screen width of @var{cpl} characters. The associated @code{show} |
| 12469 | commands display the current settings. |
| 12470 | |
| 12471 | If you specify a height of zero lines, @value{GDBN} does not pause during |
| 12472 | output no matter how long the output is. This is useful if output is to a |
| 12473 | file or to an editor buffer. |
| 12474 | |
| 12475 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} |
| 12476 | from wrapping its output. |
| 12477 | @end table |
| 12478 | |
| 12479 | @node Numbers |
| 12480 | @section Numbers |
| 12481 | @cindex number representation |
| 12482 | @cindex entering numbers |
| 12483 | |
| 12484 | You can always enter numbers in octal, decimal, or hexadecimal in |
| 12485 | @value{GDBN} by the usual conventions: octal numbers begin with |
| 12486 | @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers |
| 12487 | begin with @samp{0x}. Numbers that begin with none of these are, by |
| 12488 | default, entered in base 10; likewise, the default display for |
| 12489 | numbers---when no particular format is specified---is base 10. You can |
| 12490 | change the default base for both input and output with the @code{set |
| 12491 | radix} command. |
| 12492 | |
| 12493 | @table @code |
| 12494 | @kindex set input-radix |
| 12495 | @item set input-radix @var{base} |
| 12496 | Set the default base for numeric input. Supported choices |
| 12497 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be |
| 12498 | specified either unambiguously or using the current default radix; for |
| 12499 | example, any of |
| 12500 | |
| 12501 | @smallexample |
| 12502 | set radix 012 |
| 12503 | set radix 10. |
| 12504 | set radix 0xa |
| 12505 | @end smallexample |
| 12506 | |
| 12507 | @noindent |
| 12508 | sets the base to decimal. On the other hand, @samp{set radix 10} |
| 12509 | leaves the radix unchanged no matter what it was. |
| 12510 | |
| 12511 | @kindex set output-radix |
| 12512 | @item set output-radix @var{base} |
| 12513 | Set the default base for numeric display. Supported choices |
| 12514 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be |
| 12515 | specified either unambiguously or using the current default radix. |
| 12516 | |
| 12517 | @kindex show input-radix |
| 12518 | @item show input-radix |
| 12519 | Display the current default base for numeric input. |
| 12520 | |
| 12521 | @kindex show output-radix |
| 12522 | @item show output-radix |
| 12523 | Display the current default base for numeric display. |
| 12524 | @end table |
| 12525 | |
| 12526 | @node ABI |
| 12527 | @section Configuring the current ABI |
| 12528 | |
| 12529 | @value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your |
| 12530 | application automatically. However, sometimes you need to override its |
| 12531 | conclusions. Use these commands to manage @value{GDBN}'s view of the |
| 12532 | current ABI. |
| 12533 | |
| 12534 | @cindex OS ABI |
| 12535 | @kindex set osabi |
| 12536 | |
| 12537 | One @value{GDBN} configuration can debug binaries for multiple operating |
| 12538 | system targets, either via remote debugging or native emulation. |
| 12539 | @value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use, |
| 12540 | but you can override its conclusion using the @code{set osabi} command. |
| 12541 | One example where this is useful is in debugging of binaries which use |
| 12542 | an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does |
| 12543 | not have the same identifying marks that the standard C library for your |
| 12544 | platform provides. |
| 12545 | |
| 12546 | @table @code |
| 12547 | @item show osabi |
| 12548 | Show the OS ABI currently in use. |
| 12549 | |
| 12550 | @item set osabi |
| 12551 | With no argument, show the list of registered available OS ABI's. |
| 12552 | |
| 12553 | @item set osabi @var{abi} |
| 12554 | Set the current OS ABI to @var{abi}. |
| 12555 | @end table |
| 12556 | |
| 12557 | @cindex float promotion |
| 12558 | @kindex set coerce-float-to-double |
| 12559 | |
| 12560 | Generally, the way that an argument of type @code{float} is passed to a |
| 12561 | function depends on whether the function is prototyped. For a prototyped |
| 12562 | (i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged, |
| 12563 | according to the architecture's convention for @code{float}. For unprototyped |
| 12564 | (i.e.@: K&R style) functions, @code{float} arguments are first promoted to type |
| 12565 | @code{double} and then passed. |
| 12566 | |
| 12567 | Unfortunately, some forms of debug information do not reliably indicate whether |
| 12568 | a function is prototyped. If @value{GDBN} calls a function that is not marked |
| 12569 | as prototyped, it consults @kbd{set coerce-float-to-double}. |
| 12570 | |
| 12571 | @table @code |
| 12572 | @item set coerce-float-to-double |
| 12573 | @itemx set coerce-float-to-double on |
| 12574 | Arguments of type @code{float} will be promoted to @code{double} when passed |
| 12575 | to an unprototyped function. This is the default setting. |
| 12576 | |
| 12577 | @item set coerce-float-to-double off |
| 12578 | Arguments of type @code{float} will be passed directly to unprototyped |
| 12579 | functions. |
| 12580 | @end table |
| 12581 | |
| 12582 | @node Messages/Warnings |
| 12583 | @section Optional warnings and messages |
| 12584 | |
| 12585 | By default, @value{GDBN} is silent about its inner workings. If you are |
| 12586 | running on a slow machine, you may want to use the @code{set verbose} |
| 12587 | command. This makes @value{GDBN} tell you when it does a lengthy |
| 12588 | internal operation, so you will not think it has crashed. |
| 12589 | |
| 12590 | Currently, the messages controlled by @code{set verbose} are those |
| 12591 | which announce that the symbol table for a source file is being read; |
| 12592 | see @code{symbol-file} in @ref{Files, ,Commands to specify files}. |
| 12593 | |
| 12594 | @table @code |
| 12595 | @kindex set verbose |
| 12596 | @item set verbose on |
| 12597 | Enables @value{GDBN} output of certain informational messages. |
| 12598 | |
| 12599 | @item set verbose off |
| 12600 | Disables @value{GDBN} output of certain informational messages. |
| 12601 | |
| 12602 | @kindex show verbose |
| 12603 | @item show verbose |
| 12604 | Displays whether @code{set verbose} is on or off. |
| 12605 | @end table |
| 12606 | |
| 12607 | By default, if @value{GDBN} encounters bugs in the symbol table of an |
| 12608 | object file, it is silent; but if you are debugging a compiler, you may |
| 12609 | find this information useful (@pxref{Symbol Errors, ,Errors reading |
| 12610 | symbol files}). |
| 12611 | |
| 12612 | @table @code |
| 12613 | |
| 12614 | @kindex set complaints |
| 12615 | @item set complaints @var{limit} |
| 12616 | Permits @value{GDBN} to output @var{limit} complaints about each type of |
| 12617 | unusual symbols before becoming silent about the problem. Set |
| 12618 | @var{limit} to zero to suppress all complaints; set it to a large number |
| 12619 | to prevent complaints from being suppressed. |
| 12620 | |
| 12621 | @kindex show complaints |
| 12622 | @item show complaints |
| 12623 | Displays how many symbol complaints @value{GDBN} is permitted to produce. |
| 12624 | |
| 12625 | @end table |
| 12626 | |
| 12627 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a |
| 12628 | lot of stupid questions to confirm certain commands. For example, if |
| 12629 | you try to run a program which is already running: |
| 12630 | |
| 12631 | @smallexample |
| 12632 | (@value{GDBP}) run |
| 12633 | The program being debugged has been started already. |
| 12634 | Start it from the beginning? (y or n) |
| 12635 | @end smallexample |
| 12636 | |
| 12637 | If you are willing to unflinchingly face the consequences of your own |
| 12638 | commands, you can disable this ``feature'': |
| 12639 | |
| 12640 | @table @code |
| 12641 | |
| 12642 | @kindex set confirm |
| 12643 | @cindex flinching |
| 12644 | @cindex confirmation |
| 12645 | @cindex stupid questions |
| 12646 | @item set confirm off |
| 12647 | Disables confirmation requests. |
| 12648 | |
| 12649 | @item set confirm on |
| 12650 | Enables confirmation requests (the default). |
| 12651 | |
| 12652 | @kindex show confirm |
| 12653 | @item show confirm |
| 12654 | Displays state of confirmation requests. |
| 12655 | |
| 12656 | @end table |
| 12657 | |
| 12658 | @node Debugging Output |
| 12659 | @section Optional messages about internal happenings |
| 12660 | @table @code |
| 12661 | @kindex set debug arch |
| 12662 | @item set debug arch |
| 12663 | Turns on or off display of gdbarch debugging info. The default is off |
| 12664 | @kindex show debug arch |
| 12665 | @item show debug arch |
| 12666 | Displays the current state of displaying gdbarch debugging info. |
| 12667 | @kindex set debug event |
| 12668 | @item set debug event |
| 12669 | Turns on or off display of @value{GDBN} event debugging info. The |
| 12670 | default is off. |
| 12671 | @kindex show debug event |
| 12672 | @item show debug event |
| 12673 | Displays the current state of displaying @value{GDBN} event debugging |
| 12674 | info. |
| 12675 | @kindex set debug expression |
| 12676 | @item set debug expression |
| 12677 | Turns on or off display of @value{GDBN} expression debugging info. The |
| 12678 | default is off. |
| 12679 | @kindex show debug expression |
| 12680 | @item show debug expression |
| 12681 | Displays the current state of displaying @value{GDBN} expression |
| 12682 | debugging info. |
| 12683 | @kindex set debug overload |
| 12684 | @item set debug overload |
| 12685 | Turns on or off display of @value{GDBN} C@t{++} overload debugging |
| 12686 | info. This includes info such as ranking of functions, etc. The default |
| 12687 | is off. |
| 12688 | @kindex show debug overload |
| 12689 | @item show debug overload |
| 12690 | Displays the current state of displaying @value{GDBN} C@t{++} overload |
| 12691 | debugging info. |
| 12692 | @kindex set debug remote |
| 12693 | @cindex packets, reporting on stdout |
| 12694 | @cindex serial connections, debugging |
| 12695 | @item set debug remote |
| 12696 | Turns on or off display of reports on all packets sent back and forth across |
| 12697 | the serial line to the remote machine. The info is printed on the |
| 12698 | @value{GDBN} standard output stream. The default is off. |
| 12699 | @kindex show debug remote |
| 12700 | @item show debug remote |
| 12701 | Displays the state of display of remote packets. |
| 12702 | @kindex set debug serial |
| 12703 | @item set debug serial |
| 12704 | Turns on or off display of @value{GDBN} serial debugging info. The |
| 12705 | default is off. |
| 12706 | @kindex show debug serial |
| 12707 | @item show debug serial |
| 12708 | Displays the current state of displaying @value{GDBN} serial debugging |
| 12709 | info. |
| 12710 | @kindex set debug target |
| 12711 | @item set debug target |
| 12712 | Turns on or off display of @value{GDBN} target debugging info. This info |
| 12713 | includes what is going on at the target level of GDB, as it happens. The |
| 12714 | default is off. |
| 12715 | @kindex show debug target |
| 12716 | @item show debug target |
| 12717 | Displays the current state of displaying @value{GDBN} target debugging |
| 12718 | info. |
| 12719 | @kindex set debug varobj |
| 12720 | @item set debug varobj |
| 12721 | Turns on or off display of @value{GDBN} variable object debugging |
| 12722 | info. The default is off. |
| 12723 | @kindex show debug varobj |
| 12724 | @item show debug varobj |
| 12725 | Displays the current state of displaying @value{GDBN} variable object |
| 12726 | debugging info. |
| 12727 | @end table |
| 12728 | |
| 12729 | @node Sequences |
| 12730 | @chapter Canned Sequences of Commands |
| 12731 | |
| 12732 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint |
| 12733 | command lists}), @value{GDBN} provides two ways to store sequences of |
| 12734 | commands for execution as a unit: user-defined commands and command |
| 12735 | files. |
| 12736 | |
| 12737 | @menu |
| 12738 | * Define:: User-defined commands |
| 12739 | * Hooks:: User-defined command hooks |
| 12740 | * Command Files:: Command files |
| 12741 | * Output:: Commands for controlled output |
| 12742 | @end menu |
| 12743 | |
| 12744 | @node Define |
| 12745 | @section User-defined commands |
| 12746 | |
| 12747 | @cindex user-defined command |
| 12748 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to |
| 12749 | which you assign a new name as a command. This is done with the |
| 12750 | @code{define} command. User commands may accept up to 10 arguments |
| 12751 | separated by whitespace. Arguments are accessed within the user command |
| 12752 | via @var{$arg0@dots{}$arg9}. A trivial example: |
| 12753 | |
| 12754 | @smallexample |
| 12755 | define adder |
| 12756 | print $arg0 + $arg1 + $arg2 |
| 12757 | @end smallexample |
| 12758 | |
| 12759 | @noindent |
| 12760 | To execute the command use: |
| 12761 | |
| 12762 | @smallexample |
| 12763 | adder 1 2 3 |
| 12764 | @end smallexample |
| 12765 | |
| 12766 | @noindent |
| 12767 | This defines the command @code{adder}, which prints the sum of |
| 12768 | its three arguments. Note the arguments are text substitutions, so they may |
| 12769 | reference variables, use complex expressions, or even perform inferior |
| 12770 | functions calls. |
| 12771 | |
| 12772 | @table @code |
| 12773 | |
| 12774 | @kindex define |
| 12775 | @item define @var{commandname} |
| 12776 | Define a command named @var{commandname}. If there is already a command |
| 12777 | by that name, you are asked to confirm that you want to redefine it. |
| 12778 | |
| 12779 | The definition of the command is made up of other @value{GDBN} command lines, |
| 12780 | which are given following the @code{define} command. The end of these |
| 12781 | commands is marked by a line containing @code{end}. |
| 12782 | |
| 12783 | @kindex if |
| 12784 | @kindex else |
| 12785 | @item if |
| 12786 | Takes a single argument, which is an expression to evaluate. |
| 12787 | It is followed by a series of commands that are executed |
| 12788 | only if the expression is true (nonzero). |
| 12789 | There can then optionally be a line @code{else}, followed |
| 12790 | by a series of commands that are only executed if the expression |
| 12791 | was false. The end of the list is marked by a line containing @code{end}. |
| 12792 | |
| 12793 | @kindex while |
| 12794 | @item while |
| 12795 | The syntax is similar to @code{if}: the command takes a single argument, |
| 12796 | which is an expression to evaluate, and must be followed by the commands to |
| 12797 | execute, one per line, terminated by an @code{end}. |
| 12798 | The commands are executed repeatedly as long as the expression |
| 12799 | evaluates to true. |
| 12800 | |
| 12801 | @kindex document |
| 12802 | @item document @var{commandname} |
| 12803 | Document the user-defined command @var{commandname}, so that it can be |
| 12804 | accessed by @code{help}. The command @var{commandname} must already be |
| 12805 | defined. This command reads lines of documentation just as @code{define} |
| 12806 | reads the lines of the command definition, ending with @code{end}. |
| 12807 | After the @code{document} command is finished, @code{help} on command |
| 12808 | @var{commandname} displays the documentation you have written. |
| 12809 | |
| 12810 | You may use the @code{document} command again to change the |
| 12811 | documentation of a command. Redefining the command with @code{define} |
| 12812 | does not change the documentation. |
| 12813 | |
| 12814 | @kindex help user-defined |
| 12815 | @item help user-defined |
| 12816 | List all user-defined commands, with the first line of the documentation |
| 12817 | (if any) for each. |
| 12818 | |
| 12819 | @kindex show user |
| 12820 | @item show user |
| 12821 | @itemx show user @var{commandname} |
| 12822 | Display the @value{GDBN} commands used to define @var{commandname} (but |
| 12823 | not its documentation). If no @var{commandname} is given, display the |
| 12824 | definitions for all user-defined commands. |
| 12825 | |
| 12826 | @kindex show max-user-call-depth |
| 12827 | @kindex set max-user-call-depth |
| 12828 | @item show max-user-call-depth |
| 12829 | @itemx set max-user-call-depth |
| 12830 | The value of @code{max-user-call-depth} controls how many recursion |
| 12831 | levels are allowed in user-defined commands before GDB suspects an |
| 12832 | infinite recursion and aborts the command. |
| 12833 | |
| 12834 | @end table |
| 12835 | |
| 12836 | When user-defined commands are executed, the |
| 12837 | commands of the definition are not printed. An error in any command |
| 12838 | stops execution of the user-defined command. |
| 12839 | |
| 12840 | If used interactively, commands that would ask for confirmation proceed |
| 12841 | without asking when used inside a user-defined command. Many @value{GDBN} |
| 12842 | commands that normally print messages to say what they are doing omit the |
| 12843 | messages when used in a user-defined command. |
| 12844 | |
| 12845 | @node Hooks |
| 12846 | @section User-defined command hooks |
| 12847 | @cindex command hooks |
| 12848 | @cindex hooks, for commands |
| 12849 | @cindex hooks, pre-command |
| 12850 | |
| 12851 | @kindex hook |
| 12852 | @kindex hook- |
| 12853 | You may define @dfn{hooks}, which are a special kind of user-defined |
| 12854 | command. Whenever you run the command @samp{foo}, if the user-defined |
| 12855 | command @samp{hook-foo} exists, it is executed (with no arguments) |
| 12856 | before that command. |
| 12857 | |
| 12858 | @cindex hooks, post-command |
| 12859 | @kindex hookpost |
| 12860 | @kindex hookpost- |
| 12861 | A hook may also be defined which is run after the command you executed. |
| 12862 | Whenever you run the command @samp{foo}, if the user-defined command |
| 12863 | @samp{hookpost-foo} exists, it is executed (with no arguments) after |
| 12864 | that command. Post-execution hooks may exist simultaneously with |
| 12865 | pre-execution hooks, for the same command. |
| 12866 | |
| 12867 | It is valid for a hook to call the command which it hooks. If this |
| 12868 | occurs, the hook is not re-executed, thereby avoiding infinte recursion. |
| 12869 | |
| 12870 | @c It would be nice if hookpost could be passed a parameter indicating |
| 12871 | @c if the command it hooks executed properly or not. FIXME! |
| 12872 | |
| 12873 | @kindex stop@r{, a pseudo-command} |
| 12874 | In addition, a pseudo-command, @samp{stop} exists. Defining |
| 12875 | (@samp{hook-stop}) makes the associated commands execute every time |
| 12876 | execution stops in your program: before breakpoint commands are run, |
| 12877 | displays are printed, or the stack frame is printed. |
| 12878 | |
| 12879 | For example, to ignore @code{SIGALRM} signals while |
| 12880 | single-stepping, but treat them normally during normal execution, |
| 12881 | you could define: |
| 12882 | |
| 12883 | @smallexample |
| 12884 | define hook-stop |
| 12885 | handle SIGALRM nopass |
| 12886 | end |
| 12887 | |
| 12888 | define hook-run |
| 12889 | handle SIGALRM pass |
| 12890 | end |
| 12891 | |
| 12892 | define hook-continue |
| 12893 | handle SIGLARM pass |
| 12894 | end |
| 12895 | @end smallexample |
| 12896 | |
| 12897 | As a further example, to hook at the begining and end of the @code{echo} |
| 12898 | command, and to add extra text to the beginning and end of the message, |
| 12899 | you could define: |
| 12900 | |
| 12901 | @smallexample |
| 12902 | define hook-echo |
| 12903 | echo <<<--- |
| 12904 | end |
| 12905 | |
| 12906 | define hookpost-echo |
| 12907 | echo --->>>\n |
| 12908 | end |
| 12909 | |
| 12910 | (@value{GDBP}) echo Hello World |
| 12911 | <<<---Hello World--->>> |
| 12912 | (@value{GDBP}) |
| 12913 | |
| 12914 | @end smallexample |
| 12915 | |
| 12916 | You can define a hook for any single-word command in @value{GDBN}, but |
| 12917 | not for command aliases; you should define a hook for the basic command |
| 12918 | name, e.g. @code{backtrace} rather than @code{bt}. |
| 12919 | @c FIXME! So how does Joe User discover whether a command is an alias |
| 12920 | @c or not? |
| 12921 | If an error occurs during the execution of your hook, execution of |
| 12922 | @value{GDBN} commands stops and @value{GDBN} issues a prompt |
| 12923 | (before the command that you actually typed had a chance to run). |
| 12924 | |
| 12925 | If you try to define a hook which does not match any known command, you |
| 12926 | get a warning from the @code{define} command. |
| 12927 | |
| 12928 | @node Command Files |
| 12929 | @section Command files |
| 12930 | |
| 12931 | @cindex command files |
| 12932 | A command file for @value{GDBN} is a file of lines that are @value{GDBN} |
| 12933 | commands. Comments (lines starting with @kbd{#}) may also be included. |
| 12934 | An empty line in a command file does nothing; it does not mean to repeat |
| 12935 | the last command, as it would from the terminal. |
| 12936 | |
| 12937 | @cindex init file |
| 12938 | @cindex @file{.gdbinit} |
| 12939 | @cindex @file{gdb.ini} |
| 12940 | When you start @value{GDBN}, it automatically executes commands from its |
| 12941 | @dfn{init files}, normally called @file{.gdbinit}@footnote{The DJGPP |
| 12942 | port of @value{GDBN} uses the name @file{gdb.ini} instead, due to the |
| 12943 | limitations of file names imposed by DOS filesystems.}. |
| 12944 | During startup, @value{GDBN} does the following: |
| 12945 | |
| 12946 | @enumerate |
| 12947 | @item |
| 12948 | Reads the init file (if any) in your home directory@footnote{On |
| 12949 | DOS/Windows systems, the home directory is the one pointed to by the |
| 12950 | @code{HOME} environment variable.}. |
| 12951 | |
| 12952 | @item |
| 12953 | Processes command line options and operands. |
| 12954 | |
| 12955 | @item |
| 12956 | Reads the init file (if any) in the current working directory. |
| 12957 | |
| 12958 | @item |
| 12959 | Reads command files specified by the @samp{-x} option. |
| 12960 | @end enumerate |
| 12961 | |
| 12962 | The init file in your home directory can set options (such as @samp{set |
| 12963 | complaints}) that affect subsequent processing of command line options |
| 12964 | and operands. Init files are not executed if you use the @samp{-nx} |
| 12965 | option (@pxref{Mode Options, ,Choosing modes}). |
| 12966 | |
| 12967 | @cindex init file name |
| 12968 | On some configurations of @value{GDBN}, the init file is known by a |
| 12969 | different name (these are typically environments where a specialized |
| 12970 | form of @value{GDBN} may need to coexist with other forms, hence a |
| 12971 | different name for the specialized version's init file). These are the |
| 12972 | environments with special init file names: |
| 12973 | |
| 12974 | @cindex @file{.vxgdbinit} |
| 12975 | @itemize @bullet |
| 12976 | @item |
| 12977 | VxWorks (Wind River Systems real-time OS): @file{.vxgdbinit} |
| 12978 | |
| 12979 | @cindex @file{.os68gdbinit} |
| 12980 | @item |
| 12981 | OS68K (Enea Data Systems real-time OS): @file{.os68gdbinit} |
| 12982 | |
| 12983 | @cindex @file{.esgdbinit} |
| 12984 | @item |
| 12985 | ES-1800 (Ericsson Telecom AB M68000 emulator): @file{.esgdbinit} |
| 12986 | @end itemize |
| 12987 | |
| 12988 | You can also request the execution of a command file with the |
| 12989 | @code{source} command: |
| 12990 | |
| 12991 | @table @code |
| 12992 | @kindex source |
| 12993 | @item source @var{filename} |
| 12994 | Execute the command file @var{filename}. |
| 12995 | @end table |
| 12996 | |
| 12997 | The lines in a command file are executed sequentially. They are not |
| 12998 | printed as they are executed. An error in any command terminates |
| 12999 | execution of the command file and control is returned to the console. |
| 13000 | |
| 13001 | Commands that would ask for confirmation if used interactively proceed |
| 13002 | without asking when used in a command file. Many @value{GDBN} commands that |
| 13003 | normally print messages to say what they are doing omit the messages |
| 13004 | when called from command files. |
| 13005 | |
| 13006 | @value{GDBN} also accepts command input from standard input. In this |
| 13007 | mode, normal output goes to standard output and error output goes to |
| 13008 | standard error. Errors in a command file supplied on standard input do |
| 13009 | not terminate execution of the command file --- execution continues with |
| 13010 | the next command. |
| 13011 | |
| 13012 | @smallexample |
| 13013 | gdb < cmds > log 2>&1 |
| 13014 | @end smallexample |
| 13015 | |
| 13016 | (The syntax above will vary depending on the shell used.) This example |
| 13017 | will execute commands from the file @file{cmds}. All output and errors |
| 13018 | would be directed to @file{log}. |
| 13019 | |
| 13020 | @node Output |
| 13021 | @section Commands for controlled output |
| 13022 | |
| 13023 | During the execution of a command file or a user-defined command, normal |
| 13024 | @value{GDBN} output is suppressed; the only output that appears is what is |
| 13025 | explicitly printed by the commands in the definition. This section |
| 13026 | describes three commands useful for generating exactly the output you |
| 13027 | want. |
| 13028 | |
| 13029 | @table @code |
| 13030 | @kindex echo |
| 13031 | @item echo @var{text} |
| 13032 | @c I do not consider backslash-space a standard C escape sequence |
| 13033 | @c because it is not in ANSI. |
| 13034 | Print @var{text}. Nonprinting characters can be included in |
| 13035 | @var{text} using C escape sequences, such as @samp{\n} to print a |
| 13036 | newline. @strong{No newline is printed unless you specify one.} |
| 13037 | In addition to the standard C escape sequences, a backslash followed |
| 13038 | by a space stands for a space. This is useful for displaying a |
| 13039 | string with spaces at the beginning or the end, since leading and |
| 13040 | trailing spaces are otherwise trimmed from all arguments. |
| 13041 | To print @samp{@w{ }and foo =@w{ }}, use the command |
| 13042 | @samp{echo \@w{ }and foo = \@w{ }}. |
| 13043 | |
| 13044 | A backslash at the end of @var{text} can be used, as in C, to continue |
| 13045 | the command onto subsequent lines. For example, |
| 13046 | |
| 13047 | @smallexample |
| 13048 | echo This is some text\n\ |
| 13049 | which is continued\n\ |
| 13050 | onto several lines.\n |
| 13051 | @end smallexample |
| 13052 | |
| 13053 | produces the same output as |
| 13054 | |
| 13055 | @smallexample |
| 13056 | echo This is some text\n |
| 13057 | echo which is continued\n |
| 13058 | echo onto several lines.\n |
| 13059 | @end smallexample |
| 13060 | |
| 13061 | @kindex output |
| 13062 | @item output @var{expression} |
| 13063 | Print the value of @var{expression} and nothing but that value: no |
| 13064 | newlines, no @samp{$@var{nn} = }. The value is not entered in the |
| 13065 | value history either. @xref{Expressions, ,Expressions}, for more information |
| 13066 | on expressions. |
| 13067 | |
| 13068 | @item output/@var{fmt} @var{expression} |
| 13069 | Print the value of @var{expression} in format @var{fmt}. You can use |
| 13070 | the same formats as for @code{print}. @xref{Output Formats,,Output |
| 13071 | formats}, for more information. |
| 13072 | |
| 13073 | @kindex printf |
| 13074 | @item printf @var{string}, @var{expressions}@dots{} |
| 13075 | Print the values of the @var{expressions} under the control of |
| 13076 | @var{string}. The @var{expressions} are separated by commas and may be |
| 13077 | either numbers or pointers. Their values are printed as specified by |
| 13078 | @var{string}, exactly as if your program were to execute the C |
| 13079 | subroutine |
| 13080 | @c FIXME: the above implies that at least all ANSI C formats are |
| 13081 | @c supported, but it isn't true: %E and %G don't work (or so it seems). |
| 13082 | @c Either this is a bug, or the manual should document what formats are |
| 13083 | @c supported. |
| 13084 | |
| 13085 | @smallexample |
| 13086 | printf (@var{string}, @var{expressions}@dots{}); |
| 13087 | @end smallexample |
| 13088 | |
| 13089 | For example, you can print two values in hex like this: |
| 13090 | |
| 13091 | @smallexample |
| 13092 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo |
| 13093 | @end smallexample |
| 13094 | |
| 13095 | The only backslash-escape sequences that you can use in the format |
| 13096 | string are the simple ones that consist of backslash followed by a |
| 13097 | letter. |
| 13098 | @end table |
| 13099 | |
| 13100 | @node TUI |
| 13101 | @chapter @value{GDBN} Text User Interface |
| 13102 | @cindex TUI |
| 13103 | |
| 13104 | @menu |
| 13105 | * TUI Overview:: TUI overview |
| 13106 | * TUI Keys:: TUI key bindings |
| 13107 | * TUI Single Key Mode:: TUI single key mode |
| 13108 | * TUI Commands:: TUI specific commands |
| 13109 | * TUI Configuration:: TUI configuration variables |
| 13110 | @end menu |
| 13111 | |
| 13112 | The @value{GDBN} Text User Interface, TUI in short, |
| 13113 | is a terminal interface which uses the @code{curses} library |
| 13114 | to show the source file, the assembly output, the program registers |
| 13115 | and @value{GDBN} commands in separate text windows. |
| 13116 | The TUI is available only when @value{GDBN} is configured |
| 13117 | with the @code{--enable-tui} configure option (@pxref{Configure Options}). |
| 13118 | |
| 13119 | @node TUI Overview |
| 13120 | @section TUI overview |
| 13121 | |
| 13122 | The TUI has two display modes that can be switched while |
| 13123 | @value{GDBN} runs: |
| 13124 | |
| 13125 | @itemize @bullet |
| 13126 | @item |
| 13127 | A curses (or TUI) mode in which it displays several text |
| 13128 | windows on the terminal. |
| 13129 | |
| 13130 | @item |
| 13131 | A standard mode which corresponds to the @value{GDBN} configured without |
| 13132 | the TUI. |
| 13133 | @end itemize |
| 13134 | |
| 13135 | In the TUI mode, @value{GDBN} can display several text window |
| 13136 | on the terminal: |
| 13137 | |
| 13138 | @table @emph |
| 13139 | @item command |
| 13140 | This window is the @value{GDBN} command window with the @value{GDBN} |
| 13141 | prompt and the @value{GDBN} outputs. The @value{GDBN} input is still |
| 13142 | managed using readline but through the TUI. The @emph{command} |
| 13143 | window is always visible. |
| 13144 | |
| 13145 | @item source |
| 13146 | The source window shows the source file of the program. The current |
| 13147 | line as well as active breakpoints are displayed in this window. |
| 13148 | |
| 13149 | @item assembly |
| 13150 | The assembly window shows the disassembly output of the program. |
| 13151 | |
| 13152 | @item register |
| 13153 | This window shows the processor registers. It detects when |
| 13154 | a register is changed and when this is the case, registers that have |
| 13155 | changed are highlighted. |
| 13156 | |
| 13157 | @end table |
| 13158 | |
| 13159 | The source and assembly windows show the current program position |
| 13160 | by highlighting the current line and marking them with the @samp{>} marker. |
| 13161 | Breakpoints are also indicated with two markers. A first one |
| 13162 | indicates the breakpoint type: |
| 13163 | |
| 13164 | @table @code |
| 13165 | @item B |
| 13166 | Breakpoint which was hit at least once. |
| 13167 | |
| 13168 | @item b |
| 13169 | Breakpoint which was never hit. |
| 13170 | |
| 13171 | @item H |
| 13172 | Hardware breakpoint which was hit at least once. |
| 13173 | |
| 13174 | @item h |
| 13175 | Hardware breakpoint which was never hit. |
| 13176 | |
| 13177 | @end table |
| 13178 | |
| 13179 | The second marker indicates whether the breakpoint is enabled or not: |
| 13180 | |
| 13181 | @table @code |
| 13182 | @item + |
| 13183 | Breakpoint is enabled. |
| 13184 | |
| 13185 | @item - |
| 13186 | Breakpoint is disabled. |
| 13187 | |
| 13188 | @end table |
| 13189 | |
| 13190 | The source, assembly and register windows are attached to the thread |
| 13191 | and the frame position. They are updated when the current thread |
| 13192 | changes, when the frame changes or when the program counter changes. |
| 13193 | These three windows are arranged by the TUI according to several |
| 13194 | layouts. The layout defines which of these three windows are visible. |
| 13195 | The following layouts are available: |
| 13196 | |
| 13197 | @itemize @bullet |
| 13198 | @item |
| 13199 | source |
| 13200 | |
| 13201 | @item |
| 13202 | assembly |
| 13203 | |
| 13204 | @item |
| 13205 | source and assembly |
| 13206 | |
| 13207 | @item |
| 13208 | source and registers |
| 13209 | |
| 13210 | @item |
| 13211 | assembly and registers |
| 13212 | |
| 13213 | @end itemize |
| 13214 | |
| 13215 | On top of the command window a status line gives various information |
| 13216 | concerning the current process begin debugged. The status line is |
| 13217 | updated when the information it shows changes. The following fields |
| 13218 | are displayed: |
| 13219 | |
| 13220 | @table @emph |
| 13221 | @item target |
| 13222 | Indicates the current gdb target |
| 13223 | (@pxref{Targets, ,Specifying a Debugging Target}). |
| 13224 | |
| 13225 | @item process |
| 13226 | Gives information about the current process or thread number. |
| 13227 | When no process is being debugged, this field is set to @code{No process}. |
| 13228 | |
| 13229 | @item function |
| 13230 | Gives the current function name for the selected frame. |
| 13231 | The name is demangled if demangling is turned on (@pxref{Print Settings}). |
| 13232 | When there is no symbol corresponding to the current program counter |
| 13233 | the string @code{??} is displayed. |
| 13234 | |
| 13235 | @item line |
| 13236 | Indicates the current line number for the selected frame. |
| 13237 | When the current line number is not known the string @code{??} is displayed. |
| 13238 | |
| 13239 | @item pc |
| 13240 | Indicates the current program counter address. |
| 13241 | |
| 13242 | @end table |
| 13243 | |
| 13244 | @node TUI Keys |
| 13245 | @section TUI Key Bindings |
| 13246 | @cindex TUI key bindings |
| 13247 | |
| 13248 | The TUI installs several key bindings in the readline keymaps |
| 13249 | (@pxref{Command Line Editing}). |
| 13250 | They allow to leave or enter in the TUI mode or they operate |
| 13251 | directly on the TUI layout and windows. The TUI also provides |
| 13252 | a @emph{SingleKey} keymap which binds several keys directly to |
| 13253 | @value{GDBN} commands. The following key bindings |
| 13254 | are installed for both TUI mode and the @value{GDBN} standard mode. |
| 13255 | |
| 13256 | @table @kbd |
| 13257 | @kindex C-x C-a |
| 13258 | @item C-x C-a |
| 13259 | @kindex C-x a |
| 13260 | @itemx C-x a |
| 13261 | @kindex C-x A |
| 13262 | @itemx C-x A |
| 13263 | Enter or leave the TUI mode. When the TUI mode is left, |
| 13264 | the curses window management is left and @value{GDBN} operates using |
| 13265 | its standard mode writing on the terminal directly. When the TUI |
| 13266 | mode is entered, the control is given back to the curses windows. |
| 13267 | The screen is then refreshed. |
| 13268 | |
| 13269 | @kindex C-x 1 |
| 13270 | @item C-x 1 |
| 13271 | Use a TUI layout with only one window. The layout will |
| 13272 | either be @samp{source} or @samp{assembly}. When the TUI mode |
| 13273 | is not active, it will switch to the TUI mode. |
| 13274 | |
| 13275 | Think of this key binding as the Emacs @kbd{C-x 1} binding. |
| 13276 | |
| 13277 | @kindex C-x 2 |
| 13278 | @item C-x 2 |
| 13279 | Use a TUI layout with at least two windows. When the current |
| 13280 | layout shows already two windows, a next layout with two windows is used. |
| 13281 | When a new layout is chosen, one window will always be common to the |
| 13282 | previous layout and the new one. |
| 13283 | |
| 13284 | Think of it as the Emacs @kbd{C-x 2} binding. |
| 13285 | |
| 13286 | @kindex C-x s |
| 13287 | @item C-x s |
| 13288 | Use the TUI @emph{SingleKey} keymap that binds single key to gdb commands |
| 13289 | (@pxref{TUI Single Key Mode}). |
| 13290 | |
| 13291 | @end table |
| 13292 | |
| 13293 | The following key bindings are handled only by the TUI mode: |
| 13294 | |
| 13295 | @table @key |
| 13296 | @kindex PgUp |
| 13297 | @item PgUp |
| 13298 | Scroll the active window one page up. |
| 13299 | |
| 13300 | @kindex PgDn |
| 13301 | @item PgDn |
| 13302 | Scroll the active window one page down. |
| 13303 | |
| 13304 | @kindex Up |
| 13305 | @item Up |
| 13306 | Scroll the active window one line up. |
| 13307 | |
| 13308 | @kindex Down |
| 13309 | @item Down |
| 13310 | Scroll the active window one line down. |
| 13311 | |
| 13312 | @kindex Left |
| 13313 | @item Left |
| 13314 | Scroll the active window one column left. |
| 13315 | |
| 13316 | @kindex Right |
| 13317 | @item Right |
| 13318 | Scroll the active window one column right. |
| 13319 | |
| 13320 | @kindex C-L |
| 13321 | @item C-L |
| 13322 | Refresh the screen. |
| 13323 | |
| 13324 | @end table |
| 13325 | |
| 13326 | In the TUI mode, the arrow keys are used by the active window |
| 13327 | for scrolling. This means they are not available for readline. It is |
| 13328 | necessary to use other readline key bindings such as @key{C-p}, @key{C-n}, |
| 13329 | @key{C-b} and @key{C-f}. |
| 13330 | |
| 13331 | @node TUI Single Key Mode |
| 13332 | @section TUI Single Key Mode |
| 13333 | @cindex TUI single key mode |
| 13334 | |
| 13335 | The TUI provides a @emph{SingleKey} mode in which it installs a particular |
| 13336 | key binding in the readline keymaps to connect single keys to |
| 13337 | some gdb commands. |
| 13338 | |
| 13339 | @table @kbd |
| 13340 | @kindex c @r{(SingleKey TUI key)} |
| 13341 | @item c |
| 13342 | continue |
| 13343 | |
| 13344 | @kindex d @r{(SingleKey TUI key)} |
| 13345 | @item d |
| 13346 | down |
| 13347 | |
| 13348 | @kindex f @r{(SingleKey TUI key)} |
| 13349 | @item f |
| 13350 | finish |
| 13351 | |
| 13352 | @kindex n @r{(SingleKey TUI key)} |
| 13353 | @item n |
| 13354 | next |
| 13355 | |
| 13356 | @kindex q @r{(SingleKey TUI key)} |
| 13357 | @item q |
| 13358 | exit the @emph{SingleKey} mode. |
| 13359 | |
| 13360 | @kindex r @r{(SingleKey TUI key)} |
| 13361 | @item r |
| 13362 | run |
| 13363 | |
| 13364 | @kindex s @r{(SingleKey TUI key)} |
| 13365 | @item s |
| 13366 | step |
| 13367 | |
| 13368 | @kindex u @r{(SingleKey TUI key)} |
| 13369 | @item u |
| 13370 | up |
| 13371 | |
| 13372 | @kindex v @r{(SingleKey TUI key)} |
| 13373 | @item v |
| 13374 | info locals |
| 13375 | |
| 13376 | @kindex w @r{(SingleKey TUI key)} |
| 13377 | @item w |
| 13378 | where |
| 13379 | |
| 13380 | @end table |
| 13381 | |
| 13382 | Other keys temporarily switch to the @value{GDBN} command prompt. |
| 13383 | The key that was pressed is inserted in the editing buffer so that |
| 13384 | it is possible to type most @value{GDBN} commands without interaction |
| 13385 | with the TUI @emph{SingleKey} mode. Once the command is entered the TUI |
| 13386 | @emph{SingleKey} mode is restored. The only way to permanently leave |
| 13387 | this mode is by hitting @key{q} or @samp{@key{C-x} @key{s}}. |
| 13388 | |
| 13389 | |
| 13390 | @node TUI Commands |
| 13391 | @section TUI specific commands |
| 13392 | @cindex TUI commands |
| 13393 | |
| 13394 | The TUI has specific commands to control the text windows. |
| 13395 | These commands are always available, that is they do not depend on |
| 13396 | the current terminal mode in which @value{GDBN} runs. When @value{GDBN} |
| 13397 | is in the standard mode, using these commands will automatically switch |
| 13398 | in the TUI mode. |
| 13399 | |
| 13400 | @table @code |
| 13401 | @item info win |
| 13402 | @kindex info win |
| 13403 | List and give the size of all displayed windows. |
| 13404 | |
| 13405 | @item layout next |
| 13406 | @kindex layout next |
| 13407 | Display the next layout. |
| 13408 | |
| 13409 | @item layout prev |
| 13410 | @kindex layout prev |
| 13411 | Display the previous layout. |
| 13412 | |
| 13413 | @item layout src |
| 13414 | @kindex layout src |
| 13415 | Display the source window only. |
| 13416 | |
| 13417 | @item layout asm |
| 13418 | @kindex layout asm |
| 13419 | Display the assembly window only. |
| 13420 | |
| 13421 | @item layout split |
| 13422 | @kindex layout split |
| 13423 | Display the source and assembly window. |
| 13424 | |
| 13425 | @item layout regs |
| 13426 | @kindex layout regs |
| 13427 | Display the register window together with the source or assembly window. |
| 13428 | |
| 13429 | @item focus next | prev | src | asm | regs | split |
| 13430 | @kindex focus |
| 13431 | Set the focus to the named window. |
| 13432 | This command allows to change the active window so that scrolling keys |
| 13433 | can be affected to another window. |
| 13434 | |
| 13435 | @item refresh |
| 13436 | @kindex refresh |
| 13437 | Refresh the screen. This is similar to using @key{C-L} key. |
| 13438 | |
| 13439 | @item update |
| 13440 | @kindex update |
| 13441 | Update the source window and the current execution point. |
| 13442 | |
| 13443 | @item winheight @var{name} +@var{count} |
| 13444 | @itemx winheight @var{name} -@var{count} |
| 13445 | @kindex winheight |
| 13446 | Change the height of the window @var{name} by @var{count} |
| 13447 | lines. Positive counts increase the height, while negative counts |
| 13448 | decrease it. |
| 13449 | |
| 13450 | @end table |
| 13451 | |
| 13452 | @node TUI Configuration |
| 13453 | @section TUI configuration variables |
| 13454 | @cindex TUI configuration variables |
| 13455 | |
| 13456 | The TUI has several configuration variables that control the |
| 13457 | appearance of windows on the terminal. |
| 13458 | |
| 13459 | @table @code |
| 13460 | @item set tui border-kind @var{kind} |
| 13461 | @kindex set tui border-kind |
| 13462 | Select the border appearance for the source, assembly and register windows. |
| 13463 | The possible values are the following: |
| 13464 | @table @code |
| 13465 | @item space |
| 13466 | Use a space character to draw the border. |
| 13467 | |
| 13468 | @item ascii |
| 13469 | Use ascii characters + - and | to draw the border. |
| 13470 | |
| 13471 | @item acs |
| 13472 | Use the Alternate Character Set to draw the border. The border is |
| 13473 | drawn using character line graphics if the terminal supports them. |
| 13474 | |
| 13475 | @end table |
| 13476 | |
| 13477 | @item set tui active-border-mode @var{mode} |
| 13478 | @kindex set tui active-border-mode |
| 13479 | Select the attributes to display the border of the active window. |
| 13480 | The possible values are @code{normal}, @code{standout}, @code{reverse}, |
| 13481 | @code{half}, @code{half-standout}, @code{bold} and @code{bold-standout}. |
| 13482 | |
| 13483 | @item set tui border-mode @var{mode} |
| 13484 | @kindex set tui border-mode |
| 13485 | Select the attributes to display the border of other windows. |
| 13486 | The @var{mode} can be one of the following: |
| 13487 | @table @code |
| 13488 | @item normal |
| 13489 | Use normal attributes to display the border. |
| 13490 | |
| 13491 | @item standout |
| 13492 | Use standout mode. |
| 13493 | |
| 13494 | @item reverse |
| 13495 | Use reverse video mode. |
| 13496 | |
| 13497 | @item half |
| 13498 | Use half bright mode. |
| 13499 | |
| 13500 | @item half-standout |
| 13501 | Use half bright and standout mode. |
| 13502 | |
| 13503 | @item bold |
| 13504 | Use extra bright or bold mode. |
| 13505 | |
| 13506 | @item bold-standout |
| 13507 | Use extra bright or bold and standout mode. |
| 13508 | |
| 13509 | @end table |
| 13510 | |
| 13511 | @end table |
| 13512 | |
| 13513 | @node Emacs |
| 13514 | @chapter Using @value{GDBN} under @sc{gnu} Emacs |
| 13515 | |
| 13516 | @cindex Emacs |
| 13517 | @cindex @sc{gnu} Emacs |
| 13518 | A special interface allows you to use @sc{gnu} Emacs to view (and |
| 13519 | edit) the source files for the program you are debugging with |
| 13520 | @value{GDBN}. |
| 13521 | |
| 13522 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the |
| 13523 | executable file you want to debug as an argument. This command starts |
| 13524 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly |
| 13525 | created Emacs buffer. |
| 13526 | @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.) |
| 13527 | |
| 13528 | Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two |
| 13529 | things: |
| 13530 | |
| 13531 | @itemize @bullet |
| 13532 | @item |
| 13533 | All ``terminal'' input and output goes through the Emacs buffer. |
| 13534 | @end itemize |
| 13535 | |
| 13536 | This applies both to @value{GDBN} commands and their output, and to the input |
| 13537 | and output done by the program you are debugging. |
| 13538 | |
| 13539 | This is useful because it means that you can copy the text of previous |
| 13540 | commands and input them again; you can even use parts of the output |
| 13541 | in this way. |
| 13542 | |
| 13543 | All the facilities of Emacs' Shell mode are available for interacting |
| 13544 | with your program. In particular, you can send signals the usual |
| 13545 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a |
| 13546 | stop. |
| 13547 | |
| 13548 | @itemize @bullet |
| 13549 | @item |
| 13550 | @value{GDBN} displays source code through Emacs. |
| 13551 | @end itemize |
| 13552 | |
| 13553 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the |
| 13554 | source file for that frame and puts an arrow (@samp{=>}) at the |
| 13555 | left margin of the current line. Emacs uses a separate buffer for |
| 13556 | source display, and splits the screen to show both your @value{GDBN} session |
| 13557 | and the source. |
| 13558 | |
| 13559 | Explicit @value{GDBN} @code{list} or search commands still produce output as |
| 13560 | usual, but you probably have no reason to use them from Emacs. |
| 13561 | |
| 13562 | @quotation |
| 13563 | @emph{Warning:} If the directory where your program resides is not your |
| 13564 | current directory, it can be easy to confuse Emacs about the location of |
| 13565 | the source files, in which case the auxiliary display buffer does not |
| 13566 | appear to show your source. @value{GDBN} can find programs by searching your |
| 13567 | environment's @code{PATH} variable, so the @value{GDBN} input and output |
| 13568 | session proceeds normally; but Emacs does not get enough information |
| 13569 | back from @value{GDBN} to locate the source files in this situation. To |
| 13570 | avoid this problem, either start @value{GDBN} mode from the directory where |
| 13571 | your program resides, or specify an absolute file name when prompted for the |
| 13572 | @kbd{M-x gdb} argument. |
| 13573 | |
| 13574 | A similar confusion can result if you use the @value{GDBN} @code{file} command to |
| 13575 | switch to debugging a program in some other location, from an existing |
| 13576 | @value{GDBN} buffer in Emacs. |
| 13577 | @end quotation |
| 13578 | |
| 13579 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If |
| 13580 | you need to call @value{GDBN} by a different name (for example, if you keep |
| 13581 | several configurations around, with different names) you can set the |
| 13582 | Emacs variable @code{gdb-command-name}; for example, |
| 13583 | |
| 13584 | @smallexample |
| 13585 | (setq gdb-command-name "mygdb") |
| 13586 | @end smallexample |
| 13587 | |
| 13588 | @noindent |
| 13589 | (preceded by @kbd{M-:} or @kbd{ESC :}, or typed in the @code{*scratch*} buffer, or |
| 13590 | in your @file{.emacs} file) makes Emacs call the program named |
| 13591 | ``@code{mygdb}'' instead. |
| 13592 | |
| 13593 | In the @value{GDBN} I/O buffer, you can use these special Emacs commands in |
| 13594 | addition to the standard Shell mode commands: |
| 13595 | |
| 13596 | @table @kbd |
| 13597 | @item C-h m |
| 13598 | Describe the features of Emacs' @value{GDBN} Mode. |
| 13599 | |
| 13600 | @item M-s |
| 13601 | Execute to another source line, like the @value{GDBN} @code{step} command; also |
| 13602 | update the display window to show the current file and location. |
| 13603 | |
| 13604 | @item M-n |
| 13605 | Execute to next source line in this function, skipping all function |
| 13606 | calls, like the @value{GDBN} @code{next} command. Then update the display window |
| 13607 | to show the current file and location. |
| 13608 | |
| 13609 | @item M-i |
| 13610 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update |
| 13611 | display window accordingly. |
| 13612 | |
| 13613 | @item M-x gdb-nexti |
| 13614 | Execute to next instruction, using the @value{GDBN} @code{nexti} command; update |
| 13615 | display window accordingly. |
| 13616 | |
| 13617 | @item C-c C-f |
| 13618 | Execute until exit from the selected stack frame, like the @value{GDBN} |
| 13619 | @code{finish} command. |
| 13620 | |
| 13621 | @item M-c |
| 13622 | Continue execution of your program, like the @value{GDBN} @code{continue} |
| 13623 | command. |
| 13624 | |
| 13625 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. |
| 13626 | |
| 13627 | @item M-u |
| 13628 | Go up the number of frames indicated by the numeric argument |
| 13629 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), |
| 13630 | like the @value{GDBN} @code{up} command. |
| 13631 | |
| 13632 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. |
| 13633 | |
| 13634 | @item M-d |
| 13635 | Go down the number of frames indicated by the numeric argument, like the |
| 13636 | @value{GDBN} @code{down} command. |
| 13637 | |
| 13638 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. |
| 13639 | |
| 13640 | @item C-x & |
| 13641 | Read the number where the cursor is positioned, and insert it at the end |
| 13642 | of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code |
| 13643 | around an address that was displayed earlier, type @kbd{disassemble}; |
| 13644 | then move the cursor to the address display, and pick up the |
| 13645 | argument for @code{disassemble} by typing @kbd{C-x &}. |
| 13646 | |
| 13647 | You can customize this further by defining elements of the list |
| 13648 | @code{gdb-print-command}; once it is defined, you can format or |
| 13649 | otherwise process numbers picked up by @kbd{C-x &} before they are |
| 13650 | inserted. A numeric argument to @kbd{C-x &} indicates that you |
| 13651 | wish special formatting, and also acts as an index to pick an element of the |
| 13652 | list. If the list element is a string, the number to be inserted is |
| 13653 | formatted using the Emacs function @code{format}; otherwise the number |
| 13654 | is passed as an argument to the corresponding list element. |
| 13655 | @end table |
| 13656 | |
| 13657 | In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) |
| 13658 | tells @value{GDBN} to set a breakpoint on the source line point is on. |
| 13659 | |
| 13660 | If you accidentally delete the source-display buffer, an easy way to get |
| 13661 | it back is to type the command @code{f} in the @value{GDBN} buffer, to |
| 13662 | request a frame display; when you run under Emacs, this recreates |
| 13663 | the source buffer if necessary to show you the context of the current |
| 13664 | frame. |
| 13665 | |
| 13666 | The source files displayed in Emacs are in ordinary Emacs buffers |
| 13667 | which are visiting the source files in the usual way. You can edit |
| 13668 | the files with these buffers if you wish; but keep in mind that @value{GDBN} |
| 13669 | communicates with Emacs in terms of line numbers. If you add or |
| 13670 | delete lines from the text, the line numbers that @value{GDBN} knows cease |
| 13671 | to correspond properly with the code. |
| 13672 | |
| 13673 | @c The following dropped because Epoch is nonstandard. Reactivate |
| 13674 | @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990 |
| 13675 | @ignore |
| 13676 | @kindex Emacs Epoch environment |
| 13677 | @kindex Epoch |
| 13678 | @kindex inspect |
| 13679 | |
| 13680 | Version 18 of @sc{gnu} Emacs has a built-in window system |
| 13681 | called the @code{epoch} |
| 13682 | environment. Users of this environment can use a new command, |
| 13683 | @code{inspect} which performs identically to @code{print} except that |
| 13684 | each value is printed in its own window. |
| 13685 | @end ignore |
| 13686 | |
| 13687 | @include annotate.texi |
| 13688 | @include gdbmi.texinfo |
| 13689 | |
| 13690 | @node GDB Bugs |
| 13691 | @chapter Reporting Bugs in @value{GDBN} |
| 13692 | @cindex bugs in @value{GDBN} |
| 13693 | @cindex reporting bugs in @value{GDBN} |
| 13694 | |
| 13695 | Your bug reports play an essential role in making @value{GDBN} reliable. |
| 13696 | |
| 13697 | Reporting a bug may help you by bringing a solution to your problem, or it |
| 13698 | may not. But in any case the principal function of a bug report is to help |
| 13699 | the entire community by making the next version of @value{GDBN} work better. Bug |
| 13700 | reports are your contribution to the maintenance of @value{GDBN}. |
| 13701 | |
| 13702 | In order for a bug report to serve its purpose, you must include the |
| 13703 | information that enables us to fix the bug. |
| 13704 | |
| 13705 | @menu |
| 13706 | * Bug Criteria:: Have you found a bug? |
| 13707 | * Bug Reporting:: How to report bugs |
| 13708 | @end menu |
| 13709 | |
| 13710 | @node Bug Criteria |
| 13711 | @section Have you found a bug? |
| 13712 | @cindex bug criteria |
| 13713 | |
| 13714 | If you are not sure whether you have found a bug, here are some guidelines: |
| 13715 | |
| 13716 | @itemize @bullet |
| 13717 | @cindex fatal signal |
| 13718 | @cindex debugger crash |
| 13719 | @cindex crash of debugger |
| 13720 | @item |
| 13721 | If the debugger gets a fatal signal, for any input whatever, that is a |
| 13722 | @value{GDBN} bug. Reliable debuggers never crash. |
| 13723 | |
| 13724 | @cindex error on valid input |
| 13725 | @item |
| 13726 | If @value{GDBN} produces an error message for valid input, that is a |
| 13727 | bug. (Note that if you're cross debugging, the problem may also be |
| 13728 | somewhere in the connection to the target.) |
| 13729 | |
| 13730 | @cindex invalid input |
| 13731 | @item |
| 13732 | If @value{GDBN} does not produce an error message for invalid input, |
| 13733 | that is a bug. However, you should note that your idea of |
| 13734 | ``invalid input'' might be our idea of ``an extension'' or ``support |
| 13735 | for traditional practice''. |
| 13736 | |
| 13737 | @item |
| 13738 | If you are an experienced user of debugging tools, your suggestions |
| 13739 | for improvement of @value{GDBN} are welcome in any case. |
| 13740 | @end itemize |
| 13741 | |
| 13742 | @node Bug Reporting |
| 13743 | @section How to report bugs |
| 13744 | @cindex bug reports |
| 13745 | @cindex @value{GDBN} bugs, reporting |
| 13746 | |
| 13747 | A number of companies and individuals offer support for @sc{gnu} products. |
| 13748 | If you obtained @value{GDBN} from a support organization, we recommend you |
| 13749 | contact that organization first. |
| 13750 | |
| 13751 | You can find contact information for many support companies and |
| 13752 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs |
| 13753 | distribution. |
| 13754 | @c should add a web page ref... |
| 13755 | |
| 13756 | In any event, we also recommend that you submit bug reports for |
| 13757 | @value{GDBN}. The prefered method is to submit them directly using |
| 13758 | @uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web |
| 13759 | page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can |
| 13760 | be used. |
| 13761 | |
| 13762 | @strong{Do not send bug reports to @samp{info-gdb}, or to |
| 13763 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do |
| 13764 | not want to receive bug reports. Those that do have arranged to receive |
| 13765 | @samp{bug-gdb}. |
| 13766 | |
| 13767 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which |
| 13768 | serves as a repeater. The mailing list and the newsgroup carry exactly |
| 13769 | the same messages. Often people think of posting bug reports to the |
| 13770 | newsgroup instead of mailing them. This appears to work, but it has one |
| 13771 | problem which can be crucial: a newsgroup posting often lacks a mail |
| 13772 | path back to the sender. Thus, if we need to ask for more information, |
| 13773 | we may be unable to reach you. For this reason, it is better to send |
| 13774 | bug reports to the mailing list. |
| 13775 | |
| 13776 | The fundamental principle of reporting bugs usefully is this: |
| 13777 | @strong{report all the facts}. If you are not sure whether to state a |
| 13778 | fact or leave it out, state it! |
| 13779 | |
| 13780 | Often people omit facts because they think they know what causes the |
| 13781 | problem and assume that some details do not matter. Thus, you might |
| 13782 | assume that the name of the variable you use in an example does not matter. |
| 13783 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a |
| 13784 | stray memory reference which happens to fetch from the location where that |
| 13785 | name is stored in memory; perhaps, if the name were different, the contents |
| 13786 | of that location would fool the debugger into doing the right thing despite |
| 13787 | the bug. Play it safe and give a specific, complete example. That is the |
| 13788 | easiest thing for you to do, and the most helpful. |
| 13789 | |
| 13790 | Keep in mind that the purpose of a bug report is to enable us to fix the |
| 13791 | bug. It may be that the bug has been reported previously, but neither |
| 13792 | you nor we can know that unless your bug report is complete and |
| 13793 | self-contained. |
| 13794 | |
| 13795 | Sometimes people give a few sketchy facts and ask, ``Does this ring a |
| 13796 | bell?'' Those bug reports are useless, and we urge everyone to |
| 13797 | @emph{refuse to respond to them} except to chide the sender to report |
| 13798 | bugs properly. |
| 13799 | |
| 13800 | To enable us to fix the bug, you should include all these things: |
| 13801 | |
| 13802 | @itemize @bullet |
| 13803 | @item |
| 13804 | The version of @value{GDBN}. @value{GDBN} announces it if you start |
| 13805 | with no arguments; you can also print it at any time using @code{show |
| 13806 | version}. |
| 13807 | |
| 13808 | Without this, we will not know whether there is any point in looking for |
| 13809 | the bug in the current version of @value{GDBN}. |
| 13810 | |
| 13811 | @item |
| 13812 | The type of machine you are using, and the operating system name and |
| 13813 | version number. |
| 13814 | |
| 13815 | @item |
| 13816 | What compiler (and its version) was used to compile @value{GDBN}---e.g. |
| 13817 | ``@value{GCC}--2.8.1''. |
| 13818 | |
| 13819 | @item |
| 13820 | What compiler (and its version) was used to compile the program you are |
| 13821 | debugging---e.g. ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP |
| 13822 | C Compiler''. For GCC, you can say @code{gcc --version} to get this |
| 13823 | information; for other compilers, see the documentation for those |
| 13824 | compilers. |
| 13825 | |
| 13826 | @item |
| 13827 | The command arguments you gave the compiler to compile your example and |
| 13828 | observe the bug. For example, did you use @samp{-O}? To guarantee |
| 13829 | you will not omit something important, list them all. A copy of the |
| 13830 | Makefile (or the output from make) is sufficient. |
| 13831 | |
| 13832 | If we were to try to guess the arguments, we would probably guess wrong |
| 13833 | and then we might not encounter the bug. |
| 13834 | |
| 13835 | @item |
| 13836 | A complete input script, and all necessary source files, that will |
| 13837 | reproduce the bug. |
| 13838 | |
| 13839 | @item |
| 13840 | A description of what behavior you observe that you believe is |
| 13841 | incorrect. For example, ``It gets a fatal signal.'' |
| 13842 | |
| 13843 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we |
| 13844 | will certainly notice it. But if the bug is incorrect output, we might |
| 13845 | not notice unless it is glaringly wrong. You might as well not give us |
| 13846 | a chance to make a mistake. |
| 13847 | |
| 13848 | Even if the problem you experience is a fatal signal, you should still |
| 13849 | say so explicitly. Suppose something strange is going on, such as, your |
| 13850 | copy of @value{GDBN} is out of synch, or you have encountered a bug in |
| 13851 | the C library on your system. (This has happened!) Your copy might |
| 13852 | crash and ours would not. If you told us to expect a crash, then when |
| 13853 | ours fails to crash, we would know that the bug was not happening for |
| 13854 | us. If you had not told us to expect a crash, then we would not be able |
| 13855 | to draw any conclusion from our observations. |
| 13856 | |
| 13857 | @item |
| 13858 | If you wish to suggest changes to the @value{GDBN} source, send us context |
| 13859 | diffs. If you even discuss something in the @value{GDBN} source, refer to |
| 13860 | it by context, not by line number. |
| 13861 | |
| 13862 | The line numbers in our development sources will not match those in your |
| 13863 | sources. Your line numbers would convey no useful information to us. |
| 13864 | |
| 13865 | @end itemize |
| 13866 | |
| 13867 | Here are some things that are not necessary: |
| 13868 | |
| 13869 | @itemize @bullet |
| 13870 | @item |
| 13871 | A description of the envelope of the bug. |
| 13872 | |
| 13873 | Often people who encounter a bug spend a lot of time investigating |
| 13874 | which changes to the input file will make the bug go away and which |
| 13875 | changes will not affect it. |
| 13876 | |
| 13877 | This is often time consuming and not very useful, because the way we |
| 13878 | will find the bug is by running a single example under the debugger |
| 13879 | with breakpoints, not by pure deduction from a series of examples. |
| 13880 | We recommend that you save your time for something else. |
| 13881 | |
| 13882 | Of course, if you can find a simpler example to report @emph{instead} |
| 13883 | of the original one, that is a convenience for us. Errors in the |
| 13884 | output will be easier to spot, running under the debugger will take |
| 13885 | less time, and so on. |
| 13886 | |
| 13887 | However, simplification is not vital; if you do not want to do this, |
| 13888 | report the bug anyway and send us the entire test case you used. |
| 13889 | |
| 13890 | @item |
| 13891 | A patch for the bug. |
| 13892 | |
| 13893 | A patch for the bug does help us if it is a good one. But do not omit |
| 13894 | the necessary information, such as the test case, on the assumption that |
| 13895 | a patch is all we need. We might see problems with your patch and decide |
| 13896 | to fix the problem another way, or we might not understand it at all. |
| 13897 | |
| 13898 | Sometimes with a program as complicated as @value{GDBN} it is very hard to |
| 13899 | construct an example that will make the program follow a certain path |
| 13900 | through the code. If you do not send us the example, we will not be able |
| 13901 | to construct one, so we will not be able to verify that the bug is fixed. |
| 13902 | |
| 13903 | And if we cannot understand what bug you are trying to fix, or why your |
| 13904 | patch should be an improvement, we will not install it. A test case will |
| 13905 | help us to understand. |
| 13906 | |
| 13907 | @item |
| 13908 | A guess about what the bug is or what it depends on. |
| 13909 | |
| 13910 | Such guesses are usually wrong. Even we cannot guess right about such |
| 13911 | things without first using the debugger to find the facts. |
| 13912 | @end itemize |
| 13913 | |
| 13914 | @c The readline documentation is distributed with the readline code |
| 13915 | @c and consists of the two following files: |
| 13916 | @c rluser.texinfo |
| 13917 | @c inc-hist.texinfo |
| 13918 | @c Use -I with makeinfo to point to the appropriate directory, |
| 13919 | @c environment var TEXINPUTS with TeX. |
| 13920 | @include rluser.texinfo |
| 13921 | @include inc-hist.texinfo |
| 13922 | |
| 13923 | |
| 13924 | @node Formatting Documentation |
| 13925 | @appendix Formatting Documentation |
| 13926 | |
| 13927 | @cindex @value{GDBN} reference card |
| 13928 | @cindex reference card |
| 13929 | The @value{GDBN} 4 release includes an already-formatted reference card, ready |
| 13930 | for printing with PostScript or Ghostscript, in the @file{gdb} |
| 13931 | subdirectory of the main source directory@footnote{In |
| 13932 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} |
| 13933 | release.}. If you can use PostScript or Ghostscript with your printer, |
| 13934 | you can print the reference card immediately with @file{refcard.ps}. |
| 13935 | |
| 13936 | The release also includes the source for the reference card. You |
| 13937 | can format it, using @TeX{}, by typing: |
| 13938 | |
| 13939 | @smallexample |
| 13940 | make refcard.dvi |
| 13941 | @end smallexample |
| 13942 | |
| 13943 | The @value{GDBN} reference card is designed to print in @dfn{landscape} |
| 13944 | mode on US ``letter'' size paper; |
| 13945 | that is, on a sheet 11 inches wide by 8.5 inches |
| 13946 | high. You will need to specify this form of printing as an option to |
| 13947 | your @sc{dvi} output program. |
| 13948 | |
| 13949 | @cindex documentation |
| 13950 | |
| 13951 | All the documentation for @value{GDBN} comes as part of the machine-readable |
| 13952 | distribution. The documentation is written in Texinfo format, which is |
| 13953 | a documentation system that uses a single source file to produce both |
| 13954 | on-line information and a printed manual. You can use one of the Info |
| 13955 | formatting commands to create the on-line version of the documentation |
| 13956 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. |
| 13957 | |
| 13958 | @value{GDBN} includes an already formatted copy of the on-line Info |
| 13959 | version of this manual in the @file{gdb} subdirectory. The main Info |
| 13960 | file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to |
| 13961 | subordinate files matching @samp{gdb.info*} in the same directory. If |
| 13962 | necessary, you can print out these files, or read them with any editor; |
| 13963 | but they are easier to read using the @code{info} subsystem in @sc{gnu} |
| 13964 | Emacs or the standalone @code{info} program, available as part of the |
| 13965 | @sc{gnu} Texinfo distribution. |
| 13966 | |
| 13967 | If you want to format these Info files yourself, you need one of the |
| 13968 | Info formatting programs, such as @code{texinfo-format-buffer} or |
| 13969 | @code{makeinfo}. |
| 13970 | |
| 13971 | If you have @code{makeinfo} installed, and are in the top level |
| 13972 | @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of |
| 13973 | version @value{GDBVN}), you can make the Info file by typing: |
| 13974 | |
| 13975 | @smallexample |
| 13976 | cd gdb |
| 13977 | make gdb.info |
| 13978 | @end smallexample |
| 13979 | |
| 13980 | If you want to typeset and print copies of this manual, you need @TeX{}, |
| 13981 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the |
| 13982 | Texinfo definitions file. |
| 13983 | |
| 13984 | @TeX{} is a typesetting program; it does not print files directly, but |
| 13985 | produces output files called @sc{dvi} files. To print a typeset |
| 13986 | document, you need a program to print @sc{dvi} files. If your system |
| 13987 | has @TeX{} installed, chances are it has such a program. The precise |
| 13988 | command to use depends on your system; @kbd{lpr -d} is common; another |
| 13989 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may |
| 13990 | require a file name without any extension or a @samp{.dvi} extension. |
| 13991 | |
| 13992 | @TeX{} also requires a macro definitions file called |
| 13993 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document |
| 13994 | written in Texinfo format. On its own, @TeX{} cannot either read or |
| 13995 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB |
| 13996 | and is located in the @file{gdb-@var{version-number}/texinfo} |
| 13997 | directory. |
| 13998 | |
| 13999 | If you have @TeX{} and a @sc{dvi} printer program installed, you can |
| 14000 | typeset and print this manual. First switch to the the @file{gdb} |
| 14001 | subdirectory of the main source directory (for example, to |
| 14002 | @file{gdb-@value{GDBVN}/gdb}) and type: |
| 14003 | |
| 14004 | @smallexample |
| 14005 | make gdb.dvi |
| 14006 | @end smallexample |
| 14007 | |
| 14008 | Then give @file{gdb.dvi} to your @sc{dvi} printing program. |
| 14009 | |
| 14010 | @node Installing GDB |
| 14011 | @appendix Installing @value{GDBN} |
| 14012 | @cindex configuring @value{GDBN} |
| 14013 | @cindex installation |
| 14014 | |
| 14015 | @value{GDBN} comes with a @code{configure} script that automates the process |
| 14016 | of preparing @value{GDBN} for installation; you can then use @code{make} to |
| 14017 | build the @code{gdb} program. |
| 14018 | @iftex |
| 14019 | @c irrelevant in info file; it's as current as the code it lives with. |
| 14020 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, |
| 14021 | look at the @file{README} file in the sources; we may have improved the |
| 14022 | installation procedures since publishing this manual.} |
| 14023 | @end iftex |
| 14024 | |
| 14025 | The @value{GDBN} distribution includes all the source code you need for |
| 14026 | @value{GDBN} in a single directory, whose name is usually composed by |
| 14027 | appending the version number to @samp{gdb}. |
| 14028 | |
| 14029 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the |
| 14030 | @file{gdb-@value{GDBVN}} directory. That directory contains: |
| 14031 | |
| 14032 | @table @code |
| 14033 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} |
| 14034 | script for configuring @value{GDBN} and all its supporting libraries |
| 14035 | |
| 14036 | @item gdb-@value{GDBVN}/gdb |
| 14037 | the source specific to @value{GDBN} itself |
| 14038 | |
| 14039 | @item gdb-@value{GDBVN}/bfd |
| 14040 | source for the Binary File Descriptor library |
| 14041 | |
| 14042 | @item gdb-@value{GDBVN}/include |
| 14043 | @sc{gnu} include files |
| 14044 | |
| 14045 | @item gdb-@value{GDBVN}/libiberty |
| 14046 | source for the @samp{-liberty} free software library |
| 14047 | |
| 14048 | @item gdb-@value{GDBVN}/opcodes |
| 14049 | source for the library of opcode tables and disassemblers |
| 14050 | |
| 14051 | @item gdb-@value{GDBVN}/readline |
| 14052 | source for the @sc{gnu} command-line interface |
| 14053 | |
| 14054 | @item gdb-@value{GDBVN}/glob |
| 14055 | source for the @sc{gnu} filename pattern-matching subroutine |
| 14056 | |
| 14057 | @item gdb-@value{GDBVN}/mmalloc |
| 14058 | source for the @sc{gnu} memory-mapped malloc package |
| 14059 | @end table |
| 14060 | |
| 14061 | The simplest way to configure and build @value{GDBN} is to run @code{configure} |
| 14062 | from the @file{gdb-@var{version-number}} source directory, which in |
| 14063 | this example is the @file{gdb-@value{GDBVN}} directory. |
| 14064 | |
| 14065 | First switch to the @file{gdb-@var{version-number}} source directory |
| 14066 | if you are not already in it; then run @code{configure}. Pass the |
| 14067 | identifier for the platform on which @value{GDBN} will run as an |
| 14068 | argument. |
| 14069 | |
| 14070 | For example: |
| 14071 | |
| 14072 | @smallexample |
| 14073 | cd gdb-@value{GDBVN} |
| 14074 | ./configure @var{host} |
| 14075 | make |
| 14076 | @end smallexample |
| 14077 | |
| 14078 | @noindent |
| 14079 | where @var{host} is an identifier such as @samp{sun4} or |
| 14080 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. |
| 14081 | (You can often leave off @var{host}; @code{configure} tries to guess the |
| 14082 | correct value by examining your system.) |
| 14083 | |
| 14084 | Running @samp{configure @var{host}} and then running @code{make} builds the |
| 14085 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} |
| 14086 | libraries, then @code{gdb} itself. The configured source files, and the |
| 14087 | binaries, are left in the corresponding source directories. |
| 14088 | |
| 14089 | @need 750 |
| 14090 | @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your |
| 14091 | system does not recognize this automatically when you run a different |
| 14092 | shell, you may need to run @code{sh} on it explicitly: |
| 14093 | |
| 14094 | @smallexample |
| 14095 | sh configure @var{host} |
| 14096 | @end smallexample |
| 14097 | |
| 14098 | If you run @code{configure} from a directory that contains source |
| 14099 | directories for multiple libraries or programs, such as the |
| 14100 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} |
| 14101 | creates configuration files for every directory level underneath (unless |
| 14102 | you tell it not to, with the @samp{--norecursion} option). |
| 14103 | |
| 14104 | You can run the @code{configure} script from any of the |
| 14105 | subordinate directories in the @value{GDBN} distribution if you only want to |
| 14106 | configure that subdirectory, but be sure to specify a path to it. |
| 14107 | |
| 14108 | For example, with version @value{GDBVN}, type the following to configure only |
| 14109 | the @code{bfd} subdirectory: |
| 14110 | |
| 14111 | @smallexample |
| 14112 | @group |
| 14113 | cd gdb-@value{GDBVN}/bfd |
| 14114 | ../configure @var{host} |
| 14115 | @end group |
| 14116 | @end smallexample |
| 14117 | |
| 14118 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. |
| 14119 | However, you should make sure that the shell on your path (named by |
| 14120 | the @samp{SHELL} environment variable) is publicly readable. Remember |
| 14121 | that @value{GDBN} uses the shell to start your program---some systems refuse to |
| 14122 | let @value{GDBN} debug child processes whose programs are not readable. |
| 14123 | |
| 14124 | @menu |
| 14125 | * Separate Objdir:: Compiling @value{GDBN} in another directory |
| 14126 | * Config Names:: Specifying names for hosts and targets |
| 14127 | * Configure Options:: Summary of options for configure |
| 14128 | @end menu |
| 14129 | |
| 14130 | @node Separate Objdir |
| 14131 | @section Compiling @value{GDBN} in another directory |
| 14132 | |
| 14133 | If you want to run @value{GDBN} versions for several host or target machines, |
| 14134 | you need a different @code{gdb} compiled for each combination of |
| 14135 | host and target. @code{configure} is designed to make this easy by |
| 14136 | allowing you to generate each configuration in a separate subdirectory, |
| 14137 | rather than in the source directory. If your @code{make} program |
| 14138 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running |
| 14139 | @code{make} in each of these directories builds the @code{gdb} |
| 14140 | program specified there. |
| 14141 | |
| 14142 | To build @code{gdb} in a separate directory, run @code{configure} |
| 14143 | with the @samp{--srcdir} option to specify where to find the source. |
| 14144 | (You also need to specify a path to find @code{configure} |
| 14145 | itself from your working directory. If the path to @code{configure} |
| 14146 | would be the same as the argument to @samp{--srcdir}, you can leave out |
| 14147 | the @samp{--srcdir} option; it is assumed.) |
| 14148 | |
| 14149 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a |
| 14150 | separate directory for a Sun 4 like this: |
| 14151 | |
| 14152 | @smallexample |
| 14153 | @group |
| 14154 | cd gdb-@value{GDBVN} |
| 14155 | mkdir ../gdb-sun4 |
| 14156 | cd ../gdb-sun4 |
| 14157 | ../gdb-@value{GDBVN}/configure sun4 |
| 14158 | make |
| 14159 | @end group |
| 14160 | @end smallexample |
| 14161 | |
| 14162 | When @code{configure} builds a configuration using a remote source |
| 14163 | directory, it creates a tree for the binaries with the same structure |
| 14164 | (and using the same names) as the tree under the source directory. In |
| 14165 | the example, you'd find the Sun 4 library @file{libiberty.a} in the |
| 14166 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in |
| 14167 | @file{gdb-sun4/gdb}. |
| 14168 | |
| 14169 | One popular reason to build several @value{GDBN} configurations in separate |
| 14170 | directories is to configure @value{GDBN} for cross-compiling (where |
| 14171 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging |
| 14172 | programs that run on another machine---the @dfn{target}). |
| 14173 | You specify a cross-debugging target by |
| 14174 | giving the @samp{--target=@var{target}} option to @code{configure}. |
| 14175 | |
| 14176 | When you run @code{make} to build a program or library, you must run |
| 14177 | it in a configured directory---whatever directory you were in when you |
| 14178 | called @code{configure} (or one of its subdirectories). |
| 14179 | |
| 14180 | The @code{Makefile} that @code{configure} generates in each source |
| 14181 | directory also runs recursively. If you type @code{make} in a source |
| 14182 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured |
| 14183 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you |
| 14184 | will build all the required libraries, and then build GDB. |
| 14185 | |
| 14186 | When you have multiple hosts or targets configured in separate |
| 14187 | directories, you can run @code{make} on them in parallel (for example, |
| 14188 | if they are NFS-mounted on each of the hosts); they will not interfere |
| 14189 | with each other. |
| 14190 | |
| 14191 | @node Config Names |
| 14192 | @section Specifying names for hosts and targets |
| 14193 | |
| 14194 | The specifications used for hosts and targets in the @code{configure} |
| 14195 | script are based on a three-part naming scheme, but some short predefined |
| 14196 | aliases are also supported. The full naming scheme encodes three pieces |
| 14197 | of information in the following pattern: |
| 14198 | |
| 14199 | @smallexample |
| 14200 | @var{architecture}-@var{vendor}-@var{os} |
| 14201 | @end smallexample |
| 14202 | |
| 14203 | For example, you can use the alias @code{sun4} as a @var{host} argument, |
| 14204 | or as the value for @var{target} in a @code{--target=@var{target}} |
| 14205 | option. The equivalent full name is @samp{sparc-sun-sunos4}. |
| 14206 | |
| 14207 | The @code{configure} script accompanying @value{GDBN} does not provide |
| 14208 | any query facility to list all supported host and target names or |
| 14209 | aliases. @code{configure} calls the Bourne shell script |
| 14210 | @code{config.sub} to map abbreviations to full names; you can read the |
| 14211 | script, if you wish, or you can use it to test your guesses on |
| 14212 | abbreviations---for example: |
| 14213 | |
| 14214 | @smallexample |
| 14215 | % sh config.sub i386-linux |
| 14216 | i386-pc-linux-gnu |
| 14217 | % sh config.sub alpha-linux |
| 14218 | alpha-unknown-linux-gnu |
| 14219 | % sh config.sub hp9k700 |
| 14220 | hppa1.1-hp-hpux |
| 14221 | % sh config.sub sun4 |
| 14222 | sparc-sun-sunos4.1.1 |
| 14223 | % sh config.sub sun3 |
| 14224 | m68k-sun-sunos4.1.1 |
| 14225 | % sh config.sub i986v |
| 14226 | Invalid configuration `i986v': machine `i986v' not recognized |
| 14227 | @end smallexample |
| 14228 | |
| 14229 | @noindent |
| 14230 | @code{config.sub} is also distributed in the @value{GDBN} source |
| 14231 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). |
| 14232 | |
| 14233 | @node Configure Options |
| 14234 | @section @code{configure} options |
| 14235 | |
| 14236 | Here is a summary of the @code{configure} options and arguments that |
| 14237 | are most often useful for building @value{GDBN}. @code{configure} also has |
| 14238 | several other options not listed here. @inforef{What Configure |
| 14239 | Does,,configure.info}, for a full explanation of @code{configure}. |
| 14240 | |
| 14241 | @smallexample |
| 14242 | configure @r{[}--help@r{]} |
| 14243 | @r{[}--prefix=@var{dir}@r{]} |
| 14244 | @r{[}--exec-prefix=@var{dir}@r{]} |
| 14245 | @r{[}--srcdir=@var{dirname}@r{]} |
| 14246 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} |
| 14247 | @r{[}--target=@var{target}@r{]} |
| 14248 | @var{host} |
| 14249 | @end smallexample |
| 14250 | |
| 14251 | @noindent |
| 14252 | You may introduce options with a single @samp{-} rather than |
| 14253 | @samp{--} if you prefer; but you may abbreviate option names if you use |
| 14254 | @samp{--}. |
| 14255 | |
| 14256 | @table @code |
| 14257 | @item --help |
| 14258 | Display a quick summary of how to invoke @code{configure}. |
| 14259 | |
| 14260 | @item --prefix=@var{dir} |
| 14261 | Configure the source to install programs and files under directory |
| 14262 | @file{@var{dir}}. |
| 14263 | |
| 14264 | @item --exec-prefix=@var{dir} |
| 14265 | Configure the source to install programs under directory |
| 14266 | @file{@var{dir}}. |
| 14267 | |
| 14268 | @c avoid splitting the warning from the explanation: |
| 14269 | @need 2000 |
| 14270 | @item --srcdir=@var{dirname} |
| 14271 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another |
| 14272 | @code{make} that implements the @code{VPATH} feature.}@* |
| 14273 | Use this option to make configurations in directories separate from the |
| 14274 | @value{GDBN} source directories. Among other things, you can use this to |
| 14275 | build (or maintain) several configurations simultaneously, in separate |
| 14276 | directories. @code{configure} writes configuration specific files in |
| 14277 | the current directory, but arranges for them to use the source in the |
| 14278 | directory @var{dirname}. @code{configure} creates directories under |
| 14279 | the working directory in parallel to the source directories below |
| 14280 | @var{dirname}. |
| 14281 | |
| 14282 | @item --norecursion |
| 14283 | Configure only the directory level where @code{configure} is executed; do not |
| 14284 | propagate configuration to subdirectories. |
| 14285 | |
| 14286 | @item --target=@var{target} |
| 14287 | Configure @value{GDBN} for cross-debugging programs running on the specified |
| 14288 | @var{target}. Without this option, @value{GDBN} is configured to debug |
| 14289 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. |
| 14290 | |
| 14291 | There is no convenient way to generate a list of all available targets. |
| 14292 | |
| 14293 | @item @var{host} @dots{} |
| 14294 | Configure @value{GDBN} to run on the specified @var{host}. |
| 14295 | |
| 14296 | There is no convenient way to generate a list of all available hosts. |
| 14297 | @end table |
| 14298 | |
| 14299 | There are many other options available as well, but they are generally |
| 14300 | needed for special purposes only. |
| 14301 | |
| 14302 | @node Maintenance Commands |
| 14303 | @appendix Maintenance Commands |
| 14304 | @cindex maintenance commands |
| 14305 | @cindex internal commands |
| 14306 | |
| 14307 | In addition to commands intended for @value{GDBN} users, @value{GDBN} |
| 14308 | includes a number of commands intended for @value{GDBN} developers. |
| 14309 | These commands are provided here for reference. |
| 14310 | |
| 14311 | @table @code |
| 14312 | @kindex maint info breakpoints |
| 14313 | @item @anchor{maint info breakpoints}maint info breakpoints |
| 14314 | Using the same format as @samp{info breakpoints}, display both the |
| 14315 | breakpoints you've set explicitly, and those @value{GDBN} is using for |
| 14316 | internal purposes. Internal breakpoints are shown with negative |
| 14317 | breakpoint numbers. The type column identifies what kind of breakpoint |
| 14318 | is shown: |
| 14319 | |
| 14320 | @table @code |
| 14321 | @item breakpoint |
| 14322 | Normal, explicitly set breakpoint. |
| 14323 | |
| 14324 | @item watchpoint |
| 14325 | Normal, explicitly set watchpoint. |
| 14326 | |
| 14327 | @item longjmp |
| 14328 | Internal breakpoint, used to handle correctly stepping through |
| 14329 | @code{longjmp} calls. |
| 14330 | |
| 14331 | @item longjmp resume |
| 14332 | Internal breakpoint at the target of a @code{longjmp}. |
| 14333 | |
| 14334 | @item until |
| 14335 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. |
| 14336 | |
| 14337 | @item finish |
| 14338 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. |
| 14339 | |
| 14340 | @item shlib events |
| 14341 | Shared library events. |
| 14342 | |
| 14343 | @end table |
| 14344 | |
| 14345 | @kindex maint internal-error |
| 14346 | @kindex maint internal-warning |
| 14347 | @item maint internal-error |
| 14348 | @itemx maint internal-warning |
| 14349 | Cause @value{GDBN} to call the internal function @code{internal_error} |
| 14350 | or @code{internal_warning} and hence behave as though an internal error |
| 14351 | or internal warning has been detected. In addition to reporting the |
| 14352 | internal problem, these functions give the user the opportunity to |
| 14353 | either quit @value{GDBN} or create a core file of the current |
| 14354 | @value{GDBN} session. |
| 14355 | |
| 14356 | @smallexample |
| 14357 | (gdb) @kbd{maint internal-error testing, 1, 2} |
| 14358 | @dots{}/maint.c:121: internal-error: testing, 1, 2 |
| 14359 | A problem internal to GDB has been detected. Further |
| 14360 | debugging may prove unreliable. |
| 14361 | Quit this debugging session? (y or n) @kbd{n} |
| 14362 | Create a core file? (y or n) @kbd{n} |
| 14363 | (gdb) |
| 14364 | @end smallexample |
| 14365 | |
| 14366 | Takes an optional parameter that is used as the text of the error or |
| 14367 | warning message. |
| 14368 | |
| 14369 | @kindex maint print registers |
| 14370 | @kindex maint print raw-registers |
| 14371 | @kindex maint print cooked-registers |
| 14372 | @item maint print registers |
| 14373 | @itemx maint print raw-registers |
| 14374 | @itemx maint print cooked-registers |
| 14375 | Print @value{GDBN}'s internal register data structures. |
| 14376 | |
| 14377 | The command @samp{maint print raw-registers} includes the contents of |
| 14378 | the raw register cache; and the command @samp{maint print |
| 14379 | cooked-registers} includes the (cooked) value of all registers. |
| 14380 | @xref{Registers,, Registers, gdbint, @value{GDBN} Internals}. |
| 14381 | |
| 14382 | Takes an optional file parameter. |
| 14383 | |
| 14384 | @end table |
| 14385 | |
| 14386 | |
| 14387 | @node Remote Protocol |
| 14388 | @appendix @value{GDBN} Remote Serial Protocol |
| 14389 | |
| 14390 | @menu |
| 14391 | * Overview:: |
| 14392 | * Packets:: |
| 14393 | * Stop Reply Packets:: |
| 14394 | * General Query Packets:: |
| 14395 | * Register Packet Format:: |
| 14396 | * Examples:: |
| 14397 | @end menu |
| 14398 | |
| 14399 | @node Overview |
| 14400 | @section Overview |
| 14401 | |
| 14402 | There may be occasions when you need to know something about the |
| 14403 | protocol---for example, if there is only one serial port to your target |
| 14404 | machine, you might want your program to do something special if it |
| 14405 | recognizes a packet meant for @value{GDBN}. |
| 14406 | |
| 14407 | In the examples below, @samp{->} and @samp{<-} are used to indicate |
| 14408 | transmitted and received data respectfully. |
| 14409 | |
| 14410 | @cindex protocol, @value{GDBN} remote serial |
| 14411 | @cindex serial protocol, @value{GDBN} remote |
| 14412 | @cindex remote serial protocol |
| 14413 | All @value{GDBN} commands and responses (other than acknowledgments) are |
| 14414 | sent as a @var{packet}. A @var{packet} is introduced with the character |
| 14415 | @samp{$}, the actual @var{packet-data}, and the terminating character |
| 14416 | @samp{#} followed by a two-digit @var{checksum}: |
| 14417 | |
| 14418 | @smallexample |
| 14419 | @code{$}@var{packet-data}@code{#}@var{checksum} |
| 14420 | @end smallexample |
| 14421 | @noindent |
| 14422 | |
| 14423 | @cindex checksum, for @value{GDBN} remote |
| 14424 | @noindent |
| 14425 | The two-digit @var{checksum} is computed as the modulo 256 sum of all |
| 14426 | characters between the leading @samp{$} and the trailing @samp{#} (an |
| 14427 | eight bit unsigned checksum). |
| 14428 | |
| 14429 | Implementors should note that prior to @value{GDBN} 5.0 the protocol |
| 14430 | specification also included an optional two-digit @var{sequence-id}: |
| 14431 | |
| 14432 | @smallexample |
| 14433 | @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} |
| 14434 | @end smallexample |
| 14435 | |
| 14436 | @cindex sequence-id, for @value{GDBN} remote |
| 14437 | @noindent |
| 14438 | That @var{sequence-id} was appended to the acknowledgment. @value{GDBN} |
| 14439 | has never output @var{sequence-id}s. Stubs that handle packets added |
| 14440 | since @value{GDBN} 5.0 must not accept @var{sequence-id}. |
| 14441 | |
| 14442 | @cindex acknowledgment, for @value{GDBN} remote |
| 14443 | When either the host or the target machine receives a packet, the first |
| 14444 | response expected is an acknowledgment: either @samp{+} (to indicate |
| 14445 | the package was received correctly) or @samp{-} (to request |
| 14446 | retransmission): |
| 14447 | |
| 14448 | @smallexample |
| 14449 | -> @code{$}@var{packet-data}@code{#}@var{checksum} |
| 14450 | <- @code{+} |
| 14451 | @end smallexample |
| 14452 | @noindent |
| 14453 | |
| 14454 | The host (@value{GDBN}) sends @var{command}s, and the target (the |
| 14455 | debugging stub incorporated in your program) sends a @var{response}. In |
| 14456 | the case of step and continue @var{command}s, the response is only sent |
| 14457 | when the operation has completed (the target has again stopped). |
| 14458 | |
| 14459 | @var{packet-data} consists of a sequence of characters with the |
| 14460 | exception of @samp{#} and @samp{$} (see @samp{X} packet for additional |
| 14461 | exceptions). |
| 14462 | |
| 14463 | Fields within the packet should be separated using @samp{,} @samp{;} or |
| 14464 | @cindex remote protocol, field separator |
| 14465 | @samp{:}. Except where otherwise noted all numbers are represented in |
| 14466 | @sc{hex} with leading zeros suppressed. |
| 14467 | |
| 14468 | Implementors should note that prior to @value{GDBN} 5.0, the character |
| 14469 | @samp{:} could not appear as the third character in a packet (as it |
| 14470 | would potentially conflict with the @var{sequence-id}). |
| 14471 | |
| 14472 | Response @var{data} can be run-length encoded to save space. A @samp{*} |
| 14473 | means that the next character is an @sc{ascii} encoding giving a repeat count |
| 14474 | which stands for that many repetitions of the character preceding the |
| 14475 | @samp{*}. The encoding is @code{n+29}, yielding a printable character |
| 14476 | where @code{n >=3} (which is where rle starts to win). The printable |
| 14477 | characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric |
| 14478 | value greater than 126 should not be used. |
| 14479 | |
| 14480 | Some remote systems have used a different run-length encoding mechanism |
| 14481 | loosely refered to as the cisco encoding. Following the @samp{*} |
| 14482 | character are two hex digits that indicate the size of the packet. |
| 14483 | |
| 14484 | So: |
| 14485 | @smallexample |
| 14486 | "@code{0* }" |
| 14487 | @end smallexample |
| 14488 | @noindent |
| 14489 | means the same as "0000". |
| 14490 | |
| 14491 | The error response returned for some packets includes a two character |
| 14492 | error number. That number is not well defined. |
| 14493 | |
| 14494 | For any @var{command} not supported by the stub, an empty response |
| 14495 | (@samp{$#00}) should be returned. That way it is possible to extend the |
| 14496 | protocol. A newer @value{GDBN} can tell if a packet is supported based |
| 14497 | on that response. |
| 14498 | |
| 14499 | A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M}, |
| 14500 | @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are |
| 14501 | optional. |
| 14502 | |
| 14503 | @node Packets |
| 14504 | @section Packets |
| 14505 | |
| 14506 | The following table provides a complete list of all currently defined |
| 14507 | @var{command}s and their corresponding response @var{data}. |
| 14508 | |
| 14509 | @table @r |
| 14510 | |
| 14511 | @item @code{!} --- extended mode |
| 14512 | @cindex @code{!} packet |
| 14513 | |
| 14514 | Enable extended mode. In extended mode, the remote server is made |
| 14515 | persistent. The @samp{R} packet is used to restart the program being |
| 14516 | debugged. |
| 14517 | |
| 14518 | Reply: |
| 14519 | @table @samp |
| 14520 | @item OK |
| 14521 | The remote target both supports and has enabled extended mode. |
| 14522 | @end table |
| 14523 | |
| 14524 | @item @code{?} --- last signal |
| 14525 | @cindex @code{?} packet |
| 14526 | |
| 14527 | Indicate the reason the target halted. The reply is the same as for |
| 14528 | step and continue. |
| 14529 | |
| 14530 | Reply: |
| 14531 | @xref{Stop Reply Packets}, for the reply specifications. |
| 14532 | |
| 14533 | @item @code{a} --- reserved |
| 14534 | |
| 14535 | Reserved for future use. |
| 14536 | |
| 14537 | @item @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,@dots{}} --- set program arguments @strong{(reserved)} |
| 14538 | @cindex @code{A} packet |
| 14539 | |
| 14540 | Initialized @samp{argv[]} array passed into program. @var{arglen} |
| 14541 | specifies the number of bytes in the hex encoded byte stream @var{arg}. |
| 14542 | See @code{gdbserver} for more details. |
| 14543 | |
| 14544 | Reply: |
| 14545 | @table @samp |
| 14546 | @item OK |
| 14547 | @item E@var{NN} |
| 14548 | @end table |
| 14549 | |
| 14550 | @item @code{b}@var{baud} --- set baud @strong{(deprecated)} |
| 14551 | @cindex @code{b} packet |
| 14552 | |
| 14553 | Change the serial line speed to @var{baud}. |
| 14554 | |
| 14555 | JTC: @emph{When does the transport layer state change? When it's |
| 14556 | received, or after the ACK is transmitted. In either case, there are |
| 14557 | problems if the command or the acknowledgment packet is dropped.} |
| 14558 | |
| 14559 | Stan: @emph{If people really wanted to add something like this, and get |
| 14560 | it working for the first time, they ought to modify ser-unix.c to send |
| 14561 | some kind of out-of-band message to a specially-setup stub and have the |
| 14562 | switch happen "in between" packets, so that from remote protocol's point |
| 14563 | of view, nothing actually happened.} |
| 14564 | |
| 14565 | @item @code{B}@var{addr},@var{mode} --- set breakpoint @strong{(deprecated)} |
| 14566 | @cindex @code{B} packet |
| 14567 | |
| 14568 | Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a |
| 14569 | breakpoint at @var{addr}. |
| 14570 | |
| 14571 | This packet has been replaced by the @samp{Z} and @samp{z} packets |
| 14572 | (@pxref{insert breakpoint or watchpoint packet}). |
| 14573 | |
| 14574 | @item @code{c}@var{addr} --- continue |
| 14575 | @cindex @code{c} packet |
| 14576 | |
| 14577 | @var{addr} is address to resume. If @var{addr} is omitted, resume at |
| 14578 | current address. |
| 14579 | |
| 14580 | Reply: |
| 14581 | @xref{Stop Reply Packets}, for the reply specifications. |
| 14582 | |
| 14583 | @item @code{C}@var{sig}@code{;}@var{addr} --- continue with signal |
| 14584 | @cindex @code{C} packet |
| 14585 | |
| 14586 | Continue with signal @var{sig} (hex signal number). If |
| 14587 | @code{;}@var{addr} is omitted, resume at same address. |
| 14588 | |
| 14589 | Reply: |
| 14590 | @xref{Stop Reply Packets}, for the reply specifications. |
| 14591 | |
| 14592 | @item @code{d} --- toggle debug @strong{(deprecated)} |
| 14593 | @cindex @code{d} packet |
| 14594 | |
| 14595 | Toggle debug flag. |
| 14596 | |
| 14597 | @item @code{D} --- detach |
| 14598 | @cindex @code{D} packet |
| 14599 | |
| 14600 | Detach @value{GDBN} from the remote system. Sent to the remote target |
| 14601 | before @value{GDBN} disconnects. |
| 14602 | |
| 14603 | Reply: |
| 14604 | @table @samp |
| 14605 | @item @emph{no response} |
| 14606 | @value{GDBN} does not check for any response after sending this packet. |
| 14607 | @end table |
| 14608 | |
| 14609 | @item @code{e} --- reserved |
| 14610 | |
| 14611 | Reserved for future use. |
| 14612 | |
| 14613 | @item @code{E} --- reserved |
| 14614 | |
| 14615 | Reserved for future use. |
| 14616 | |
| 14617 | @item @code{f} --- reserved |
| 14618 | |
| 14619 | Reserved for future use. |
| 14620 | |
| 14621 | @item @code{F} --- reserved |
| 14622 | |
| 14623 | Reserved for future use. |
| 14624 | |
| 14625 | @item @code{g} --- read registers |
| 14626 | @anchor{read registers packet} |
| 14627 | @cindex @code{g} packet |
| 14628 | |
| 14629 | Read general registers. |
| 14630 | |
| 14631 | Reply: |
| 14632 | @table @samp |
| 14633 | @item @var{XX@dots{}} |
| 14634 | Each byte of register data is described by two hex digits. The bytes |
| 14635 | with the register are transmitted in target byte order. The size of |
| 14636 | each register and their position within the @samp{g} @var{packet} are |
| 14637 | determined by the @value{GDBN} internal macros @var{REGISTER_RAW_SIZE} |
| 14638 | and @var{REGISTER_NAME} macros. The specification of several standard |
| 14639 | @code{g} packets is specified below. |
| 14640 | @item E@var{NN} |
| 14641 | for an error. |
| 14642 | @end table |
| 14643 | |
| 14644 | @item @code{G}@var{XX@dots{}} --- write regs |
| 14645 | @cindex @code{G} packet |
| 14646 | |
| 14647 | @xref{read registers packet}, for a description of the @var{XX@dots{}} |
| 14648 | data. |
| 14649 | |
| 14650 | Reply: |
| 14651 | @table @samp |
| 14652 | @item OK |
| 14653 | for success |
| 14654 | @item E@var{NN} |
| 14655 | for an error |
| 14656 | @end table |
| 14657 | |
| 14658 | @item @code{h} --- reserved |
| 14659 | |
| 14660 | Reserved for future use. |
| 14661 | |
| 14662 | @item @code{H}@var{c}@var{t@dots{}} --- set thread |
| 14663 | @cindex @code{H} packet |
| 14664 | |
| 14665 | Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, |
| 14666 | @samp{G}, et.al.). @var{c} depends on the operation to be performed: it |
| 14667 | should be @samp{c} for step and continue operations, @samp{g} for other |
| 14668 | operations. The thread designator @var{t@dots{}} may be -1, meaning all |
| 14669 | the threads, a thread number, or zero which means pick any thread. |
| 14670 | |
| 14671 | Reply: |
| 14672 | @table @samp |
| 14673 | @item OK |
| 14674 | for success |
| 14675 | @item E@var{NN} |
| 14676 | for an error |
| 14677 | @end table |
| 14678 | |
| 14679 | @c FIXME: JTC: |
| 14680 | @c 'H': How restrictive (or permissive) is the thread model. If a |
| 14681 | @c thread is selected and stopped, are other threads allowed |
| 14682 | @c to continue to execute? As I mentioned above, I think the |
| 14683 | @c semantics of each command when a thread is selected must be |
| 14684 | @c described. For example: |
| 14685 | @c |
| 14686 | @c 'g': If the stub supports threads and a specific thread is |
| 14687 | @c selected, returns the register block from that thread; |
| 14688 | @c otherwise returns current registers. |
| 14689 | @c |
| 14690 | @c 'G' If the stub supports threads and a specific thread is |
| 14691 | @c selected, sets the registers of the register block of |
| 14692 | @c that thread; otherwise sets current registers. |
| 14693 | |
| 14694 | @item @code{i}@var{addr}@code{,}@var{nnn} --- cycle step @strong{(draft)} |
| 14695 | @anchor{cycle step packet} |
| 14696 | @cindex @code{i} packet |
| 14697 | |
| 14698 | Step the remote target by a single clock cycle. If @code{,}@var{nnn} is |
| 14699 | present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle |
| 14700 | step starting at that address. |
| 14701 | |
| 14702 | @item @code{I} --- signal then cycle step @strong{(reserved)} |
| 14703 | @cindex @code{I} packet |
| 14704 | |
| 14705 | @xref{step with signal packet}. @xref{cycle step packet}. |
| 14706 | |
| 14707 | @item @code{j} --- reserved |
| 14708 | |
| 14709 | Reserved for future use. |
| 14710 | |
| 14711 | @item @code{J} --- reserved |
| 14712 | |
| 14713 | Reserved for future use. |
| 14714 | |
| 14715 | @item @code{k} --- kill request |
| 14716 | @cindex @code{k} packet |
| 14717 | |
| 14718 | FIXME: @emph{There is no description of how to operate when a specific |
| 14719 | thread context has been selected (i.e.@: does 'k' kill only that |
| 14720 | thread?)}. |
| 14721 | |
| 14722 | @item @code{K} --- reserved |
| 14723 | |
| 14724 | Reserved for future use. |
| 14725 | |
| 14726 | @item @code{l} --- reserved |
| 14727 | |
| 14728 | Reserved for future use. |
| 14729 | |
| 14730 | @item @code{L} --- reserved |
| 14731 | |
| 14732 | Reserved for future use. |
| 14733 | |
| 14734 | @item @code{m}@var{addr}@code{,}@var{length} --- read memory |
| 14735 | @cindex @code{m} packet |
| 14736 | |
| 14737 | Read @var{length} bytes of memory starting at address @var{addr}. |
| 14738 | Neither @value{GDBN} nor the stub assume that sized memory transfers are |
| 14739 | assumed using word aligned accesses. FIXME: @emph{A word aligned memory |
| 14740 | transfer mechanism is needed.} |
| 14741 | |
| 14742 | Reply: |
| 14743 | @table @samp |
| 14744 | @item @var{XX@dots{}} |
| 14745 | @var{XX@dots{}} is mem contents. Can be fewer bytes than requested if able |
| 14746 | to read only part of the data. Neither @value{GDBN} nor the stub assume |
| 14747 | that sized memory transfers are assumed using word aligned |
| 14748 | accesses. FIXME: @emph{A word aligned memory transfer mechanism is |
| 14749 | needed.} |
| 14750 | @item E@var{NN} |
| 14751 | @var{NN} is errno |
| 14752 | @end table |
| 14753 | |
| 14754 | @item @code{M}@var{addr},@var{length}@code{:}@var{XX@dots{}} --- write mem |
| 14755 | @cindex @code{M} packet |
| 14756 | |
| 14757 | Write @var{length} bytes of memory starting at address @var{addr}. |
| 14758 | @var{XX@dots{}} is the data. |
| 14759 | |
| 14760 | Reply: |
| 14761 | @table @samp |
| 14762 | @item OK |
| 14763 | for success |
| 14764 | @item E@var{NN} |
| 14765 | for an error (this includes the case where only part of the data was |
| 14766 | written). |
| 14767 | @end table |
| 14768 | |
| 14769 | @item @code{n} --- reserved |
| 14770 | |
| 14771 | Reserved for future use. |
| 14772 | |
| 14773 | @item @code{N} --- reserved |
| 14774 | |
| 14775 | Reserved for future use. |
| 14776 | |
| 14777 | @item @code{o} --- reserved |
| 14778 | |
| 14779 | Reserved for future use. |
| 14780 | |
| 14781 | @item @code{O} --- reserved |
| 14782 | |
| 14783 | Reserved for future use. |
| 14784 | |
| 14785 | @item @code{p}@var{n@dots{}} --- read reg @strong{(reserved)} |
| 14786 | @cindex @code{p} packet |
| 14787 | |
| 14788 | @xref{write register packet}. |
| 14789 | |
| 14790 | Reply: |
| 14791 | @table @samp |
| 14792 | @item @var{r@dots{}.} |
| 14793 | The hex encoded value of the register in target byte order. |
| 14794 | @end table |
| 14795 | |
| 14796 | @item @code{P}@var{n@dots{}}@code{=}@var{r@dots{}} --- write register |
| 14797 | @anchor{write register packet} |
| 14798 | @cindex @code{P} packet |
| 14799 | |
| 14800 | Write register @var{n@dots{}} with value @var{r@dots{}}, which contains two hex |
| 14801 | digits for each byte in the register (target byte order). |
| 14802 | |
| 14803 | Reply: |
| 14804 | @table @samp |
| 14805 | @item OK |
| 14806 | for success |
| 14807 | @item E@var{NN} |
| 14808 | for an error |
| 14809 | @end table |
| 14810 | |
| 14811 | @item @code{q}@var{query} --- general query |
| 14812 | @anchor{general query packet} |
| 14813 | @cindex @code{q} packet |
| 14814 | |
| 14815 | Request info about @var{query}. In general @value{GDBN} queries have a |
| 14816 | leading upper case letter. Custom vendor queries should use a company |
| 14817 | prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may optionally |
| 14818 | be followed by a @samp{,} or @samp{;} separated list. Stubs must ensure |
| 14819 | that they match the full @var{query} name. |
| 14820 | |
| 14821 | Reply: |
| 14822 | @table @samp |
| 14823 | @item @var{XX@dots{}} |
| 14824 | Hex encoded data from query. The reply can not be empty. |
| 14825 | @item E@var{NN} |
| 14826 | error reply |
| 14827 | @item |
| 14828 | Indicating an unrecognized @var{query}. |
| 14829 | @end table |
| 14830 | |
| 14831 | @item @code{Q}@var{var}@code{=}@var{val} --- general set |
| 14832 | @cindex @code{Q} packet |
| 14833 | |
| 14834 | Set value of @var{var} to @var{val}. |
| 14835 | |
| 14836 | @xref{general query packet}, for a discussion of naming conventions. |
| 14837 | |
| 14838 | @item @code{r} --- reset @strong{(deprecated)} |
| 14839 | @cindex @code{r} packet |
| 14840 | |
| 14841 | Reset the entire system. |
| 14842 | |
| 14843 | @item @code{R}@var{XX} --- remote restart |
| 14844 | @cindex @code{R} packet |
| 14845 | |
| 14846 | Restart the program being debugged. @var{XX}, while needed, is ignored. |
| 14847 | This packet is only available in extended mode. |
| 14848 | |
| 14849 | Reply: |
| 14850 | @table @samp |
| 14851 | @item @emph{no reply} |
| 14852 | The @samp{R} packet has no reply. |
| 14853 | @end table |
| 14854 | |
| 14855 | @item @code{s}@var{addr} --- step |
| 14856 | @cindex @code{s} packet |
| 14857 | |
| 14858 | @var{addr} is address to resume. If @var{addr} is omitted, resume at |
| 14859 | same address. |
| 14860 | |
| 14861 | Reply: |
| 14862 | @xref{Stop Reply Packets}, for the reply specifications. |
| 14863 | |
| 14864 | @item @code{S}@var{sig}@code{;}@var{addr} --- step with signal |
| 14865 | @anchor{step with signal packet} |
| 14866 | @cindex @code{S} packet |
| 14867 | |
| 14868 | Like @samp{C} but step not continue. |
| 14869 | |
| 14870 | Reply: |
| 14871 | @xref{Stop Reply Packets}, for the reply specifications. |
| 14872 | |
| 14873 | @item @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} --- search |
| 14874 | @cindex @code{t} packet |
| 14875 | |
| 14876 | Search backwards starting at address @var{addr} for a match with pattern |
| 14877 | @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes. |
| 14878 | @var{addr} must be at least 3 digits. |
| 14879 | |
| 14880 | @item @code{T}@var{XX} --- thread alive |
| 14881 | @cindex @code{T} packet |
| 14882 | |
| 14883 | Find out if the thread XX is alive. |
| 14884 | |
| 14885 | Reply: |
| 14886 | @table @samp |
| 14887 | @item OK |
| 14888 | thread is still alive |
| 14889 | @item E@var{NN} |
| 14890 | thread is dead |
| 14891 | @end table |
| 14892 | |
| 14893 | @item @code{u} --- reserved |
| 14894 | |
| 14895 | Reserved for future use. |
| 14896 | |
| 14897 | @item @code{U} --- reserved |
| 14898 | |
| 14899 | Reserved for future use. |
| 14900 | |
| 14901 | @item @code{v} --- reserved |
| 14902 | |
| 14903 | Reserved for future use. |
| 14904 | |
| 14905 | @item @code{V} --- reserved |
| 14906 | |
| 14907 | Reserved for future use. |
| 14908 | |
| 14909 | @item @code{w} --- reserved |
| 14910 | |
| 14911 | Reserved for future use. |
| 14912 | |
| 14913 | @item @code{W} --- reserved |
| 14914 | |
| 14915 | Reserved for future use. |
| 14916 | |
| 14917 | @item @code{x} --- reserved |
| 14918 | |
| 14919 | Reserved for future use. |
| 14920 | |
| 14921 | @item @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX@dots{}} --- write mem (binary) |
| 14922 | @cindex @code{X} packet |
| 14923 | |
| 14924 | @var{addr} is address, @var{length} is number of bytes, @var{XX@dots{}} |
| 14925 | is binary data. The characters @code{$}, @code{#}, and @code{0x7d} are |
| 14926 | escaped using @code{0x7d}. |
| 14927 | |
| 14928 | Reply: |
| 14929 | @table @samp |
| 14930 | @item OK |
| 14931 | for success |
| 14932 | @item E@var{NN} |
| 14933 | for an error |
| 14934 | @end table |
| 14935 | |
| 14936 | @item @code{y} --- reserved |
| 14937 | |
| 14938 | Reserved for future use. |
| 14939 | |
| 14940 | @item @code{Y} reserved |
| 14941 | |
| 14942 | Reserved for future use. |
| 14943 | |
| 14944 | @item @code{z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- remove breakpoint or watchpoint @strong{(draft)} |
| 14945 | @itemx @code{Z}@var{type}@code{,}@var{addr}@code{,}@var{length} --- insert breakpoint or watchpoint @strong{(draft)} |
| 14946 | @anchor{insert breakpoint or watchpoint packet} |
| 14947 | @cindex @code{z} packet |
| 14948 | @cindex @code{Z} packets |
| 14949 | |
| 14950 | Insert (@code{Z}) or remove (@code{z}) a @var{type} breakpoint or |
| 14951 | watchpoint starting at address @var{address} and covering the next |
| 14952 | @var{length} bytes. |
| 14953 | |
| 14954 | Each breakpoint and watchpoint packet @var{type} is documented |
| 14955 | separately. |
| 14956 | |
| 14957 | @emph{Implementation notes: A remote target shall return an empty string |
| 14958 | for an unrecognized breakpoint or watchpoint packet @var{type}. A |
| 14959 | remote target shall support either both or neither of a given |
| 14960 | @code{Z}@var{type}@dots{} and @code{z}@var{type}@dots{} packet pair. To |
| 14961 | avoid potential problems with duplicate packets, the operations should |
| 14962 | be implemented in an idempotent way.} |
| 14963 | |
| 14964 | @item @code{z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- remove memory breakpoint @strong{(draft)} |
| 14965 | @item @code{Z}@code{0}@code{,}@var{addr}@code{,}@var{length} --- insert memory breakpoint @strong{(draft)} |
| 14966 | @cindex @code{z0} packet |
| 14967 | @cindex @code{Z0} packet |
| 14968 | |
| 14969 | Insert (@code{Z0}) or remove (@code{z0}) a memory breakpoint at address |
| 14970 | @code{addr} of size @code{length}. |
| 14971 | |
| 14972 | A memory breakpoint is implemented by replacing the instruction at |
| 14973 | @var{addr} with a software breakpoint or trap instruction. The |
| 14974 | @code{length} is used by targets that indicates the size of the |
| 14975 | breakpoint (in bytes) that should be inserted (e.g., the @sc{arm} and |
| 14976 | @sc{mips} can insert either a 2 or 4 byte breakpoint). |
| 14977 | |
| 14978 | @emph{Implementation note: It is possible for a target to copy or move |
| 14979 | code that contains memory breakpoints (e.g., when implementing |
| 14980 | overlays). The behavior of this packet, in the presence of such a |
| 14981 | target, is not defined.} |
| 14982 | |
| 14983 | Reply: |
| 14984 | @table @samp |
| 14985 | @item OK |
| 14986 | success |
| 14987 | @item |
| 14988 | not supported |
| 14989 | @item E@var{NN} |
| 14990 | for an error |
| 14991 | @end table |
| 14992 | |
| 14993 | @item @code{z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- remove hardware breakpoint @strong{(draft)} |
| 14994 | @item @code{Z}@code{1}@code{,}@var{addr}@code{,}@var{length} --- insert hardware breakpoint @strong{(draft)} |
| 14995 | @cindex @code{z1} packet |
| 14996 | @cindex @code{Z1} packet |
| 14997 | |
| 14998 | Insert (@code{Z1}) or remove (@code{z1}) a hardware breakpoint at |
| 14999 | address @code{addr} of size @code{length}. |
| 15000 | |
| 15001 | A hardware breakpoint is implemented using a mechanism that is not |
| 15002 | dependant on being able to modify the target's memory. |
| 15003 | |
| 15004 | @emph{Implementation note: A hardware breakpoint is not affected by code |
| 15005 | movement.} |
| 15006 | |
| 15007 | Reply: |
| 15008 | @table @samp |
| 15009 | @item OK |
| 15010 | success |
| 15011 | @item |
| 15012 | not supported |
| 15013 | @item E@var{NN} |
| 15014 | for an error |
| 15015 | @end table |
| 15016 | |
| 15017 | @item @code{z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- remove write watchpoint @strong{(draft)} |
| 15018 | @item @code{Z}@code{2}@code{,}@var{addr}@code{,}@var{length} --- insert write watchpoint @strong{(draft)} |
| 15019 | @cindex @code{z2} packet |
| 15020 | @cindex @code{Z2} packet |
| 15021 | |
| 15022 | Insert (@code{Z2}) or remove (@code{z2}) a write watchpoint. |
| 15023 | |
| 15024 | Reply: |
| 15025 | @table @samp |
| 15026 | @item OK |
| 15027 | success |
| 15028 | @item |
| 15029 | not supported |
| 15030 | @item E@var{NN} |
| 15031 | for an error |
| 15032 | @end table |
| 15033 | |
| 15034 | @item @code{z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- remove read watchpoint @strong{(draft)} |
| 15035 | @item @code{Z}@code{3}@code{,}@var{addr}@code{,}@var{length} --- insert read watchpoint @strong{(draft)} |
| 15036 | @cindex @code{z3} packet |
| 15037 | @cindex @code{Z3} packet |
| 15038 | |
| 15039 | Insert (@code{Z3}) or remove (@code{z3}) a read watchpoint. |
| 15040 | |
| 15041 | Reply: |
| 15042 | @table @samp |
| 15043 | @item OK |
| 15044 | success |
| 15045 | @item |
| 15046 | not supported |
| 15047 | @item E@var{NN} |
| 15048 | for an error |
| 15049 | @end table |
| 15050 | |
| 15051 | @item @code{z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- remove access watchpoint @strong{(draft)} |
| 15052 | @item @code{Z}@code{4}@code{,}@var{addr}@code{,}@var{length} --- insert access watchpoint @strong{(draft)} |
| 15053 | @cindex @code{z4} packet |
| 15054 | @cindex @code{Z4} packet |
| 15055 | |
| 15056 | Insert (@code{Z4}) or remove (@code{z4}) an access watchpoint. |
| 15057 | |
| 15058 | Reply: |
| 15059 | @table @samp |
| 15060 | @item OK |
| 15061 | success |
| 15062 | @item |
| 15063 | not supported |
| 15064 | @item E@var{NN} |
| 15065 | for an error |
| 15066 | @end table |
| 15067 | |
| 15068 | @end table |
| 15069 | |
| 15070 | @node Stop Reply Packets |
| 15071 | @section Stop Reply Packets |
| 15072 | @cindex stop reply packets |
| 15073 | |
| 15074 | The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can |
| 15075 | receive any of the below as a reply. In the case of the @samp{C}, |
| 15076 | @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned |
| 15077 | when the target halts. In the below the exact meaning of @samp{signal |
| 15078 | number} is poorly defined. In general one of the UNIX signal numbering |
| 15079 | conventions is used. |
| 15080 | |
| 15081 | @table @samp |
| 15082 | |
| 15083 | @item S@var{AA} |
| 15084 | @var{AA} is the signal number |
| 15085 | |
| 15086 | @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;} |
| 15087 | @cindex @code{T} packet reply |
| 15088 | |
| 15089 | @var{AA} = two hex digit signal number; @var{n...} = register number |
| 15090 | (hex), @var{r...} = target byte ordered register contents, size defined |
| 15091 | by @code{REGISTER_RAW_SIZE}; @var{n...} = @samp{thread}, @var{r...} = |
| 15092 | thread process ID, this is a hex integer; @var{n...} = (@samp{watch} | |
| 15093 | @samp{rwatch} | @samp{awatch}, @var{r...} = data address, this is a hex |
| 15094 | integer; @var{n...} = other string not starting with valid hex digit. |
| 15095 | @value{GDBN} should ignore this @var{n...}, @var{r...} pair and go on |
| 15096 | to the next. This way we can extend the protocol. |
| 15097 | |
| 15098 | @item W@var{AA} |
| 15099 | |
| 15100 | The process exited, and @var{AA} is the exit status. This is only |
| 15101 | applicable to certain targets. |
| 15102 | |
| 15103 | @item X@var{AA} |
| 15104 | |
| 15105 | The process terminated with signal @var{AA}. |
| 15106 | |
| 15107 | @item N@var{AA};@var{t@dots{}};@var{d@dots{}};@var{b@dots{}} @strong{(obsolete)} |
| 15108 | |
| 15109 | @var{AA} = signal number; @var{t@dots{}} = address of symbol |
| 15110 | @code{_start}; @var{d@dots{}} = base of data section; @var{b@dots{}} = |
| 15111 | base of bss section. @emph{Note: only used by Cisco Systems targets. |
| 15112 | The difference between this reply and the @samp{qOffsets} query is that |
| 15113 | the @samp{N} packet may arrive spontaneously whereas the @samp{qOffsets} |
| 15114 | is a query initiated by the host debugger.} |
| 15115 | |
| 15116 | @item O@var{XX@dots{}} |
| 15117 | |
| 15118 | @var{XX@dots{}} is hex encoding of @sc{ascii} data. This can happen at |
| 15119 | any time while the program is running and the debugger should continue |
| 15120 | to wait for @samp{W}, @samp{T}, etc. |
| 15121 | |
| 15122 | @end table |
| 15123 | |
| 15124 | @node General Query Packets |
| 15125 | @section General Query Packets |
| 15126 | |
| 15127 | The following set and query packets have already been defined. |
| 15128 | |
| 15129 | @table @r |
| 15130 | |
| 15131 | @item @code{q}@code{C} --- current thread |
| 15132 | |
| 15133 | Return the current thread id. |
| 15134 | |
| 15135 | Reply: |
| 15136 | @table @samp |
| 15137 | @item @code{QC}@var{pid} |
| 15138 | Where @var{pid} is a HEX encoded 16 bit process id. |
| 15139 | @item * |
| 15140 | Any other reply implies the old pid. |
| 15141 | @end table |
| 15142 | |
| 15143 | @item @code{q}@code{fThreadInfo} -- all thread ids |
| 15144 | |
| 15145 | @code{q}@code{sThreadInfo} |
| 15146 | |
| 15147 | Obtain a list of active thread ids from the target (OS). Since there |
| 15148 | may be too many active threads to fit into one reply packet, this query |
| 15149 | works iteratively: it may require more than one query/reply sequence to |
| 15150 | obtain the entire list of threads. The first query of the sequence will |
| 15151 | be the @code{qf}@code{ThreadInfo} query; subsequent queries in the |
| 15152 | sequence will be the @code{qs}@code{ThreadInfo} query. |
| 15153 | |
| 15154 | NOTE: replaces the @code{qL} query (see below). |
| 15155 | |
| 15156 | Reply: |
| 15157 | @table @samp |
| 15158 | @item @code{m}@var{id} |
| 15159 | A single thread id |
| 15160 | @item @code{m}@var{id},@var{id}@dots{} |
| 15161 | a comma-separated list of thread ids |
| 15162 | @item @code{l} |
| 15163 | (lower case 'el') denotes end of list. |
| 15164 | @end table |
| 15165 | |
| 15166 | In response to each query, the target will reply with a list of one or |
| 15167 | more thread ids, in big-endian hex, separated by commas. @value{GDBN} |
| 15168 | will respond to each reply with a request for more thread ids (using the |
| 15169 | @code{qs} form of the query), until the target responds with @code{l} |
| 15170 | (lower-case el, for @code{'last'}). |
| 15171 | |
| 15172 | @item @code{q}@code{ThreadExtraInfo}@code{,}@var{id} --- extra thread info |
| 15173 | |
| 15174 | Where @var{id} is a thread-id in big-endian hex. Obtain a printable |
| 15175 | string description of a thread's attributes from the target OS. This |
| 15176 | string may contain anything that the target OS thinks is interesting for |
| 15177 | @value{GDBN} to tell the user about the thread. The string is displayed |
| 15178 | in @value{GDBN}'s @samp{info threads} display. Some examples of |
| 15179 | possible thread extra info strings are ``Runnable'', or ``Blocked on |
| 15180 | Mutex''. |
| 15181 | |
| 15182 | Reply: |
| 15183 | @table @samp |
| 15184 | @item @var{XX@dots{}} |
| 15185 | Where @var{XX@dots{}} is a hex encoding of @sc{ascii} data, comprising |
| 15186 | the printable string containing the extra information about the thread's |
| 15187 | attributes. |
| 15188 | @end table |
| 15189 | |
| 15190 | @item @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} --- query @var{LIST} or @var{threadLIST} @strong{(deprecated)} |
| 15191 | |
| 15192 | Obtain thread information from RTOS. Where: @var{startflag} (one hex |
| 15193 | digit) is one to indicate the first query and zero to indicate a |
| 15194 | subsequent query; @var{threadcount} (two hex digits) is the maximum |
| 15195 | number of threads the response packet can contain; and @var{nextthread} |
| 15196 | (eight hex digits), for subsequent queries (@var{startflag} is zero), is |
| 15197 | returned in the response as @var{argthread}. |
| 15198 | |
| 15199 | NOTE: this query is replaced by the @code{q}@code{fThreadInfo} query |
| 15200 | (see above). |
| 15201 | |
| 15202 | Reply: |
| 15203 | @table @samp |
| 15204 | @item @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread@dots{}} |
| 15205 | Where: @var{count} (two hex digits) is the number of threads being |
| 15206 | returned; @var{done} (one hex digit) is zero to indicate more threads |
| 15207 | and one indicates no further threads; @var{argthreadid} (eight hex |
| 15208 | digits) is @var{nextthread} from the request packet; @var{thread@dots{}} |
| 15209 | is a sequence of thread IDs from the target. @var{threadid} (eight hex |
| 15210 | digits). See @code{remote.c:parse_threadlist_response()}. |
| 15211 | @end table |
| 15212 | |
| 15213 | @item @code{q}@code{CRC:}@var{addr}@code{,}@var{length} --- compute CRC of memory block |
| 15214 | |
| 15215 | Reply: |
| 15216 | @table @samp |
| 15217 | @item @code{E}@var{NN} |
| 15218 | An error (such as memory fault) |
| 15219 | @item @code{C}@var{CRC32} |
| 15220 | A 32 bit cyclic redundancy check of the specified memory region. |
| 15221 | @end table |
| 15222 | |
| 15223 | @item @code{q}@code{Offsets} --- query sect offs |
| 15224 | |
| 15225 | Get section offsets that the target used when re-locating the downloaded |
| 15226 | image. @emph{Note: while a @code{Bss} offset is included in the |
| 15227 | response, @value{GDBN} ignores this and instead applies the @code{Data} |
| 15228 | offset to the @code{Bss} section.} |
| 15229 | |
| 15230 | Reply: |
| 15231 | @table @samp |
| 15232 | @item @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz} |
| 15233 | @end table |
| 15234 | |
| 15235 | @item @code{q}@code{P}@var{mode}@var{threadid} --- thread info request |
| 15236 | |
| 15237 | Returns information on @var{threadid}. Where: @var{mode} is a hex |
| 15238 | encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID. |
| 15239 | |
| 15240 | Reply: |
| 15241 | @table @samp |
| 15242 | @item * |
| 15243 | @end table |
| 15244 | |
| 15245 | See @code{remote.c:remote_unpack_thread_info_response()}. |
| 15246 | |
| 15247 | @item @code{q}@code{Rcmd,}@var{command} --- remote command |
| 15248 | |
| 15249 | @var{command} (hex encoded) is passed to the local interpreter for |
| 15250 | execution. Invalid commands should be reported using the output string. |
| 15251 | Before the final result packet, the target may also respond with a |
| 15252 | number of intermediate @code{O}@var{output} console output packets. |
| 15253 | @emph{Implementors should note that providing access to a stubs's |
| 15254 | interpreter may have security implications}. |
| 15255 | |
| 15256 | Reply: |
| 15257 | @table @samp |
| 15258 | @item OK |
| 15259 | A command response with no output. |
| 15260 | @item @var{OUTPUT} |
| 15261 | A command response with the hex encoded output string @var{OUTPUT}. |
| 15262 | @item @code{E}@var{NN} |
| 15263 | Indicate a badly formed request. |
| 15264 | @item @samp{} |
| 15265 | When @samp{q}@samp{Rcmd} is not recognized. |
| 15266 | @end table |
| 15267 | |
| 15268 | @item @code{qSymbol::} --- symbol lookup |
| 15269 | |
| 15270 | Notify the target that @value{GDBN} is prepared to serve symbol lookup |
| 15271 | requests. Accept requests from the target for the values of symbols. |
| 15272 | |
| 15273 | Reply: |
| 15274 | @table @samp |
| 15275 | @item @code{OK} |
| 15276 | The target does not need to look up any (more) symbols. |
| 15277 | @item @code{qSymbol:}@var{sym_name} |
| 15278 | The target requests the value of symbol @var{sym_name} (hex encoded). |
| 15279 | @value{GDBN} may provide the value by using the |
| 15280 | @code{qSymbol:}@var{sym_value}:@var{sym_name} message, described below. |
| 15281 | @end table |
| 15282 | |
| 15283 | @item @code{qSymbol:}@var{sym_value}:@var{sym_name} --- symbol value |
| 15284 | |
| 15285 | Set the value of @var{sym_name} to @var{sym_value}. |
| 15286 | |
| 15287 | @var{sym_name} (hex encoded) is the name of a symbol whose value the |
| 15288 | target has previously requested. |
| 15289 | |
| 15290 | @var{sym_value} (hex) is the value for symbol @var{sym_name}. If |
| 15291 | @value{GDBN} cannot supply a value for @var{sym_name}, then this field |
| 15292 | will be empty. |
| 15293 | |
| 15294 | Reply: |
| 15295 | @table @samp |
| 15296 | @item @code{OK} |
| 15297 | The target does not need to look up any (more) symbols. |
| 15298 | @item @code{qSymbol:}@var{sym_name} |
| 15299 | The target requests the value of a new symbol @var{sym_name} (hex |
| 15300 | encoded). @value{GDBN} will continue to supply the values of symbols |
| 15301 | (if available), until the target ceases to request them. |
| 15302 | @end table |
| 15303 | |
| 15304 | @end table |
| 15305 | |
| 15306 | @node Register Packet Format |
| 15307 | @section Register Packet Format |
| 15308 | |
| 15309 | The following @samp{g}/@samp{G} packets have previously been defined. |
| 15310 | In the below, some thirty-two bit registers are transferred as |
| 15311 | sixty-four bits. Those registers should be zero/sign extended (which?) |
| 15312 | to fill the space allocated. Register bytes are transfered in target |
| 15313 | byte order. The two nibbles within a register byte are transfered |
| 15314 | most-significant - least-significant. |
| 15315 | |
| 15316 | @table @r |
| 15317 | |
| 15318 | @item MIPS32 |
| 15319 | |
| 15320 | All registers are transfered as thirty-two bit quantities in the order: |
| 15321 | 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point |
| 15322 | registers; fsr; fir; fp. |
| 15323 | |
| 15324 | @item MIPS64 |
| 15325 | |
| 15326 | All registers are transfered as sixty-four bit quantities (including |
| 15327 | thirty-two bit registers such as @code{sr}). The ordering is the same |
| 15328 | as @code{MIPS32}. |
| 15329 | |
| 15330 | @end table |
| 15331 | |
| 15332 | @node Examples |
| 15333 | @section Examples |
| 15334 | |
| 15335 | Example sequence of a target being re-started. Notice how the restart |
| 15336 | does not get any direct output: |
| 15337 | |
| 15338 | @smallexample |
| 15339 | -> @code{R00} |
| 15340 | <- @code{+} |
| 15341 | @emph{target restarts} |
| 15342 | -> @code{?} |
| 15343 | <- @code{+} |
| 15344 | <- @code{T001:1234123412341234} |
| 15345 | -> @code{+} |
| 15346 | @end smallexample |
| 15347 | |
| 15348 | Example sequence of a target being stepped by a single instruction: |
| 15349 | |
| 15350 | @smallexample |
| 15351 | -> @code{G1445@dots{}} |
| 15352 | <- @code{+} |
| 15353 | -> @code{s} |
| 15354 | <- @code{+} |
| 15355 | @emph{time passes} |
| 15356 | <- @code{T001:1234123412341234} |
| 15357 | -> @code{+} |
| 15358 | -> @code{g} |
| 15359 | <- @code{+} |
| 15360 | <- @code{1455@dots{}} |
| 15361 | -> @code{+} |
| 15362 | @end smallexample |
| 15363 | |
| 15364 | @include gpl.texi |
| 15365 | |
| 15366 | @include fdl.texi |
| 15367 | |
| 15368 | @node Index |
| 15369 | @unnumbered Index |
| 15370 | |
| 15371 | @printindex cp |
| 15372 | |
| 15373 | @tex |
| 15374 | % I think something like @colophon should be in texinfo. In the |
| 15375 | % meantime: |
| 15376 | \long\def\colophon{\hbox to0pt{}\vfill |
| 15377 | \centerline{The body of this manual is set in} |
| 15378 | \centerline{\fontname\tenrm,} |
| 15379 | \centerline{with headings in {\bf\fontname\tenbf}} |
| 15380 | \centerline{and examples in {\tt\fontname\tentt}.} |
| 15381 | \centerline{{\it\fontname\tenit\/},} |
| 15382 | \centerline{{\bf\fontname\tenbf}, and} |
| 15383 | \centerline{{\sl\fontname\tensl\/}} |
| 15384 | \centerline{are used for emphasis.}\vfill} |
| 15385 | \page\colophon |
| 15386 | % Blame: doc@cygnus.com, 1991. |
| 15387 | @end tex |
| 15388 | |
| 15389 | @bye |