1 What has changed since GDB-3.5?
2 (Organized release by release)
4 *** Changes in GDB-4.7:
10 * New cross target hosts
12 HP/Apollo 68k (under the BSD domain)
16 Fujitsu SparcLite - This is a Sparc without floating-point intended for
17 imbedded applications.
21 As always, G++ support keeps on impoving. We now deal with Cfront style
22 name mangling, and can even extract type info from mangled symbols.
24 Calling of virtual functions and inferior methods has been improved as well.
26 GDB can now automatically figure out which symbol mangling style your C++
31 The crash that was occuring when debugging Sun Ansi-C compiled binaries has
32 been fixed. This was due mishandling of the extra SO stabs that the
33 compiler was outputting.
35 We also finally got Ultrix 4.2 up and running in house, and were able to
36 really fix core file support!
38 It was discovered that the reason that single-stepping was so slow on all
39 of the Mips based platforms (primarily SGI and DEC) was that we were trying
40 to demangle and lookup a symbol used for internal purposes on every instruction
41 that was being stepped through. Changing the name of that symbol so that it
42 couldn't be mistaken for a C++ mangled symbol sped things up a great deal.
44 We also sped up symbol lookups in general by getting much smarter about
45 when symbol mangling was necessary.
49 A bunch of work has been done to improve the general 29k support. In
50 particular, a new user controllable variable 'call_scratch_address' can be
51 used to specify the location of a scratch area to be used when GDB needs to
52 call a function in the target. This was necessary because the usual method
53 of putting the scratch area on the stack was not feasible for systems that
54 have seperate instruction and data spaces.
56 We also did a bunch of work on the 29k UDI (Universal Debugger Interface)
57 code, but at the last minute we discovered that we didn't have all of the
58 appropriate copyright paperwork, and had to yank it all out. We are working
59 with AMD to resolve this, and hope to have it available soon.
63 We have made some improvements in the remote serial line protocol which should
64 speed up things a great deal (especially for targets with lots of registers).
65 The remote code now supports a new `expedited status' ('T') message which
66 replaces the old 'S' status message. This message has a much more flexible
67 format which allows the remote stub to send an arbitrary set of registers
68 whenever the stub takes control. This greatly speeds up stepping, as the
69 stub can supply only the registers GDB requires during this process. It
70 eliminates the need to fetch the entire register set for each instruction being
73 GDB was also made a bit smarter about reading registers from the target. It
74 now makes much more use of the cache. In effect, it now implements a
75 write-through cache, and only reads the registers when if the target has run.
77 There is also a new remote stub for Sparc processors. You can find it in
78 gdb-4.7/gdb/sparc-stub.c. This was written to support the SparcLite product,
79 but actually contains no SparcLite specific code. It should run on any
80 stand-alone Sparc processor with a serial port that can be dedicated to GDB
83 * Host/native/target split
85 GDB has had some major internal surgery recently in order to untangle some
86 of the mess related to supporting hosts and remote targets. Now, when you
87 configure GDB for a remote target, it may no longer load in all of the host
88 support for debugging local programs. This means that if you make a GDB to
89 debug a remote vxWorks target from a Sun4 host, you will no longer get
90 ptrace() or Sun4 core file support. This surgery was necessary to ensure
91 that arbitrary host/target combinations were possible. In particular, it
92 makes it much more practical to build new configurations for remote targets
93 that in the past were only hosts.
95 The primary concept behind the detanglement was to seperate the code into
96 one of three categories. The host category is for code that is host
97 specific, and can only be compiled for a particular host configuration.
98 The target category is for code which is target specific, but can be
99 compiled on any host. The native category is for the situation where the
100 host and target are the same system (this usually means that you are going
101 to debug an inferior process).
105 There is a new opcodes library which will contain all of the disassembly
106 routines, and opcode tables at some point in the future. At present, it
107 only contains Sparc and Z8000 routines. This was done in order to get the
108 assembler and the debugger to share these routines.
110 The file gdb-4.7/gdb/doc/stabs.texinfo is a (relatively) complete reference
111 to the stabs symbol info used by the debugger. It is (as far as we know)
112 the only published document on this fascinating topic.
114 There are now pre-command hooks that are used to attach arbitrary commands
115 to any command. The commands in the hook will be executed prior to the
116 users command. You can creat a hook which will be executed whenever the
119 BFD now supports the Zilog Z8000 microprocessor.
121 And, of course, many bugs have been fixed.
123 *** Changes in GDB-4.6:
125 * Better support for C++ function names
127 GDB now accepts as input the "demangled form" of C++ overloaded function
128 names and member function names, and can do command completion on such names
129 (using TAB, TAB-TAB, and ESC-?). The names have to be quoted with a pair of
130 single quotes. Examples are 'func (int, long)' and 'obj::operator==(obj&)'.
131 Make use of command completion, it is your friend.
133 GDB also now accepts a variety of C++ mangled symbol formats. They are
134 the GNU g++ style, the Cfront (ARM) style, and the Lucid (lcc) style.
135 You can tell GDB which format to use by doing a 'set demangle-style {gnu,
136 lucid, cfront, auto}'. 'gnu' is the default. Do a 'set demangle-style foo'
137 for the list of formats.
139 * G++ symbol mangling problem
141 Recent versions of gcc have a bug in how they emit debugging information for
142 C++ methods (when using dbx-style stabs). The file 'gcc.patch' (in this
143 directory) can be applied to gcc to fix the problem. Alternatively, if you
144 can't fix gcc, you can #define GCC_MANGLE_BUG when compling gdb/symtab.c. The
145 usual symptom is difficulty with setting breakpoints on methods. GDB complains
146 about the method being non-existent. (We believe that version 2.2.2 of GCC has
149 * New 'maintenance' command
151 All of the commands related to hacking GDB internals have been moved out of
152 the main command set, and now live behind the 'maintenance' command. This
153 can also be abbreviated as 'mt'. The following changes were made:
155 dump-me -> maintenance dump-me
156 info all-breakpoints -> maintenance info breakpoints
157 printmsyms -> maintenance print msyms
158 printobjfiles -> maintenance print objfiles
159 printpsyms -> maintenance print psymbols
160 printsyms -> maintenance print symbols
162 The following commands are new:
164 maintenance demangle Call internal GDB demangler routine to
165 demangle a C++ link name and prints the result.
166 maintenance print type Print a type chain for a given symbol
168 * Change to .gdbinit file processing
170 We now read the $HOME/.gdbinit file before processing the argv arguments
171 (e.g. reading symbol files or core files). This allows global parameters to
172 be set, which will apply during the symbol reading. The ./.gdbinit is still
173 read after argv processing.
175 * New hosts supported
177 Solaris-2.0 !!! sparc-sun-solaris2 or sun4sol2
179 Linux support i386-unknown-linux or linux
181 We are also including code to support the HP/PA running BSD and HPUX. This
182 is almost guaranteed not to work, as we didn't have time to test or build it
183 for this release. We are including it so that the more adventurous (or
184 masochistic) of you can play with it. We also had major problems with the
185 fact that the compiler that we got from HP doesn't support the -g option.
188 * New targets supported
190 Hitachi H8/300 h8300-hitachi-hms or h8300hms
192 * More smarts about finding #include files
194 GDB now remembers the compilation directory for all include files, and for
195 all files from which C is generated (like yacc and lex sources). This
196 greatly improves GDB's ability to find yacc/lex sources, and include files,
197 especially if you are debugging your program from a directory different from
198 the one that contains your sources.
200 We also fixed a bug which caused difficulty with listing and setting
201 breakpoints in include files which contain C code. (In the past, you had to
202 try twice in order to list an include file that you hadn't looked at before.)
204 * Interesting infernals change
206 GDB now deals with arbitrary numbers of sections, where the symbols for each
207 section must be relocated relative to that section's landing place in the
208 target's address space. This work was needed to support ELF with embedded
209 stabs used by Solaris-2.0.
211 * Bug fixes (of course!)
213 There have been loads of fixes for the following things:
214 mips, rs6000, 29k/udi, m68k, g++, type handling, elf/dwarf, m88k,
215 i960, stabs, DOS(GO32), procfs, etc...
217 See the ChangeLog for details.
219 *** Changes in GDB-4.5:
221 * New machines supported (host and target)
223 IBM RS6000 running AIX rs6000-ibm-aix or rs6000
225 SGI Irix-4.x mips-sgi-irix4 or iris4
229 GDB now uses a new memory manager called mmalloc, based on gmalloc.
230 Mmalloc is capable of handling mutiple heaps of memory. It is also
231 capable of saving a heap to a file, and then mapping it back in later.
232 This can be used to greatly speedup the startup of GDB by using a
233 pre-parsed symbol table which lives in a mmalloc managed heap. For
234 more details, please read mmalloc/mmalloc.texi.
238 The 'info proc' command (SVR4 only) has been enhanced quite a bit. See
239 'help info proc' for details.
241 * MIPS ecoff symbol table format
243 The code that reads MIPS symbol table format is now supported on all hosts.
244 Thanks to MIPS for releasing the sym.h and symconst.h files to make this
247 * File name changes for MS-DOS
249 Many files in the config directories have been renamed to make it easier to
250 support GDB on MS-DOSe systems (which have very restrictive file name
251 conventions :-( ). MS-DOSe host support (under DJ Delorie's GO32
252 environment) is close to working but has some remaining problems. Note
253 that debugging of DOS programs is not supported, due to limitations
254 in the ``operating system'', but it can be used to host cross-debugging.
256 * Cross byte order fixes
258 Many fixes have been made to support cross debugging of Sparc and MIPS
259 targets from hosts whose byte order differs.
261 * New -mapped and -readnow options
263 If memory-mapped files are available on your system through the 'mmap'
264 system call, you can use the -mapped option on the `file' or
265 `symbol-file' commands to cause GDB to write the symbols from your
266 program into a reusable file. If the program you are debugging is
267 called `/path/fred', the mapped symbol file will be `./fred.syms'.
268 Future GDB debugging sessions will notice the presence of this file,
269 and will quickly map in symbol information from it, rather than reading
270 the symbol table from the executable program. Using the '-mapped'
271 option in a GDB `file' or `symbol-file' command has the same effect as
272 starting GDB with the '-mapped' command-line option.
274 You can cause GDB to read the entire symbol table immediately by using
275 the '-readnow' option with any of the commands that load symbol table
276 information (or on the GDB command line). This makes the command
277 slower, but makes future operations faster.
279 The -mapped and -readnow options are typically combined in order to
280 build a `fred.syms' file that contains complete symbol information.
281 A simple GDB invocation to do nothing but build a `.syms' file for future
284 gdb -batch -nx -mapped -readnow programname
286 The `.syms' file is specific to the host machine on which GDB is run.
287 It holds an exact image of GDB's internal symbol table. It cannot be
288 shared across multiple host platforms.
292 GDB is now capable of stepping and nexting over longjmp(), _longjmp(), and
293 siglongjmp() without losing control. This feature has not yet been ported to
294 all systems. It currently works on many 386 platforms, all MIPS-based
295 platforms (SGI, DECstation, etc), and Sun3/4.
299 Preliminary work has been put in to support the new Solaris OS from Sun. At
300 this time, it can control and debug processes, but it is not capable of
305 As always, many many bug fixes. The major areas were with g++, and mipsread.
306 People using the MIPS-based platforms should experience fewer mysterious
307 crashes and trashed symbol tables.
309 *** Changes in GDB-4.4:
311 * New machines supported (host and target)
313 SCO Unix on i386 IBM PC clones i386-sco-sysv or i386sco
315 BSD Reno on Vax vax-dec-bsd
316 Ultrix on Vax vax-dec-ultrix
318 * New machines supported (target)
320 AMD 29000 embedded, using EBMON a29k-none-none
324 GDB continues to improve its handling of C++. `References' work better.
325 The demangler has also been improved, and now deals with symbols mangled as
326 per the Annotated C++ Reference Guide.
328 GDB also now handles `stabs' symbol information embedded in MIPS
329 `ecoff' symbol tables. Since the ecoff format was not easily
330 extensible to handle new languages such as C++, this appeared to be a
331 good way to put C++ debugging info into MIPS binaries. This option
332 will be supported in the GNU C compiler, version 2, when it is
335 * New features for SVR4
337 GDB now handles SVR4 shared libraries, in the same fashion as SunOS
338 shared libraries. Debugging dynamically linked programs should present
339 only minor differences from debugging statically linked programs.
341 The `info proc' command will print out information about any process
342 on an SVR4 system (including the one you are debugging). At the moment,
343 it prints the address mappings of the process.
345 If you bring up GDB on another SVR4 system, please send mail to
346 bug-gdb@prep.ai.mit.edu to let us know what changes were reqired (if any).
348 * Better dynamic linking support in SunOS
350 Reading symbols from shared libraries which contain debugging symbols
351 now works properly. However, there remain issues such as automatic
352 skipping of `transfer vector' code during function calls, which
353 make it harder to debug code in a shared library, than to debug the
354 same code linked statically.
358 GDB is now using the latest `getopt' routines from the FSF. This
359 version accepts the -- prefix for options with long names. GDB will
360 continue to accept the old forms (-option and +option) as well.
361 Various single letter abbreviations for options have been explicity
362 added to the option table so that they won't get overshadowed in the
363 future by other options that begin with the same letter.
367 The `cleanup_undefined_types' bug that many of you noticed has been squashed.
368 Many assorted bugs have been handled. Many more remain to be handled.
369 See the various ChangeLog files (primarily in gdb and bfd) for details.
372 *** Changes in GDB-4.3:
374 * New machines supported (host and target)
376 Amiga 3000 running Amix m68k-cbm-svr4 or amix
377 NCR 3000 386 running SVR4 i386-ncr-svr4 or ncr3000
378 Motorola Delta 88000 running Sys V m88k-motorola-sysv or delta88
380 * Almost SCO Unix support
382 We had hoped to support:
383 SCO Unix on i386 IBM PC clones i386-sco-sysv or i386sco
384 (except for core file support), but we discovered very late in the release
385 that it has problems with process groups that render gdb unusable. Sorry
386 about that. I encourage people to fix it and post the fixes.
388 * Preliminary ELF and DWARF support
390 GDB can read ELF object files on System V Release 4, and can handle
391 debugging records for C, in DWARF format, in ELF files. This support
392 is preliminary. If you bring up GDB on another SVR4 system, please
393 send mail to bug-gdb@prep.ai.mit.edu to let us know what changes were
398 GDB now uses the latest `readline' library. One user-visible change
399 is that two tabs will list possible command completions, which previously
400 required typing M-? (meta-question mark, or ESC ?).
404 The `stepi' bug that many of you noticed has been squashed.
405 Many bugs in C++ have been handled. Many more remain to be handled.
406 See the various ChangeLog files (primarily in gdb and bfd) for details.
408 * State of the MIPS world (in case you wondered):
410 GDB can understand the symbol tables emitted by the compilers
411 supplied by most vendors of MIPS-based machines, including DEC. These
412 symbol tables are in a format that essentially nobody else uses.
414 Some versions of gcc come with an assembler post-processor called
415 mips-tfile. This program is required if you want to do source-level
416 debugging of gcc-compiled programs. I believe FSF does not ship
417 mips-tfile with gcc version 1, but it will eventually come with gcc
420 Debugging of g++ output remains a problem. g++ version 1.xx does not
421 really support it at all. (If you're lucky, you should be able to get
422 line numbers and stack traces to work, but no parameters or local
423 variables.) With some work it should be possible to improve the
426 When gcc version 2 is released, you will have somewhat better luck.
427 However, even then you will get confusing results for inheritance and
430 We will eventually provide full debugging of g++ output on
431 DECstations. This will probably involve some kind of stabs-in-ecoff
432 encapulation, but the details have not been worked out yet.
435 *** Changes in GDB-4.2:
437 * Improved configuration
439 Only one copy of `configure' exists now, and it is not self-modifying.
440 Porting BFD is simpler.
444 The `step' and `next' commands now only stop at the first instruction
445 of a source line. This prevents the multiple stops that used to occur
446 in switch statements, for-loops, etc. `Step' continues to stop if a
447 function that has debugging information is called within the line.
451 Lots of small bugs fixed. More remain.
453 * New host supported (not target)
455 Intel 386 PC clone running Mach i386-none-mach
458 *** Changes in GDB-4.1:
460 * Multiple source language support
462 GDB now has internal scaffolding to handle several source languages.
463 It determines the type of each source file from its filename extension,
464 and will switch expression parsing and number formatting to match the
465 language of the function in the currently selected stack frame.
466 You can also specifically set the language to be used, with
467 `set language c' or `set language modula-2'.
471 GDB now has preliminary support for the GNU Modula-2 compiler,
472 currently under development at the State University of New York at
473 Buffalo. Development of both GDB and the GNU Modula-2 compiler will
474 continue through the fall of 1991 and into 1992.
476 Other Modula-2 compilers are currently not supported, and attempting to
477 debug programs compiled with them will likely result in an error as the
478 symbol table is read. Feel free to work on it, though!
480 There are hooks in GDB for strict type checking and range checking,
481 in the `Modula-2 philosophy', but they do not currently work.
485 GDB can now write to executable and core files (e.g. patch
486 a variable's value). You must turn this switch on, specify
487 the file ("exec foo" or "core foo"), *then* modify it, e.g.
488 by assigning a new value to a variable. Modifications take
491 * Automatic SunOS shared library reading
493 When you run your program, GDB automatically determines where its
494 shared libraries (if any) have been loaded, and reads their symbols.
495 The `share' command is no longer needed. This also works when
496 examining core files.
500 You can specify the number of lines that the `list' command shows.
503 * New machines supported (host and target)
505 SGI Iris (MIPS) running Irix V3: mips-sgi-irix or iris
506 Sony NEWS (68K) running NEWSOS 3.x: m68k-sony-sysv or news
507 Ultracomputer (29K) running Sym1: a29k-nyu-sym1 or ultra3
509 * New hosts supported (not targets)
511 IBM RT/PC: romp-ibm-aix or rtpc
513 * New targets supported (not hosts)
515 AMD 29000 embedded with COFF a29k-none-coff
516 AMD 29000 embedded with a.out a29k-none-aout
517 Ultracomputer remote kernel debug a29k-nyu-kern
519 * New remote interfaces
525 *** Changes in GDB-4.0:
529 Wide output is wrapped at good places to make the output more readable.
531 Gdb now supports cross-debugging from a host machine of one type to a
532 target machine of another type. Communication with the target system
533 is over serial lines. The ``target'' command handles connecting to the
534 remote system; the ``load'' command will download a program into the
535 remote system. Serial stubs for the m68k and i386 are provided. Gdb
536 also supports debugging of realtime processes running under VxWorks,
537 using SunRPC Remote Procedure Calls over TCP/IP to talk to a debugger
538 stub on the target system.
540 New CPUs supported include the AMD 29000 and Intel 960.
542 GDB now reads object files and symbol tables via a ``binary file''
543 library, which allows a single copy of GDB to debug programs of multiple
544 object file types such as a.out and coff.
546 There is now a GDB reference card in "doc/refcard.tex". (Make targets
547 refcard.dvi and refcard.ps are available to format it).
550 * Control-Variable user interface simplified
552 All variables that control the operation of the debugger can be set
553 by the ``set'' command, and displayed by the ``show'' command.
555 For example, ``set prompt new-gdb=>'' will change your prompt to new-gdb=>.
556 ``Show prompt'' produces the response:
557 Gdb's prompt is new-gdb=>.
559 What follows are the NEW set commands. The command ``help set'' will
560 print a complete list of old and new set commands. ``help set FOO''
561 will give a longer description of the variable FOO. ``show'' will show
562 all of the variable descriptions and their current settings.
564 confirm on/off: Enables warning questions for operations that are
565 hard to recover from, e.g. rerunning the program while
566 it is already running. Default is ON.
568 editing on/off: Enables EMACS style command line editing
569 of input. Previous lines can be recalled with
570 control-P, the current line can be edited with control-B,
571 you can search for commands with control-R, etc.
574 history filename NAME: NAME is where the gdb command history
575 will be stored. The default is .gdb_history,
576 or the value of the environment variable
579 history size N: The size, in commands, of the command history. The
580 default is 256, or the value of the environment variable
583 history save on/off: If this value is set to ON, the history file will
584 be saved after exiting gdb. If set to OFF, the
585 file will not be saved. The default is OFF.
587 history expansion on/off: If this value is set to ON, then csh-like
588 history expansion will be performed on
589 command line input. The default is OFF.
591 radix N: Sets the default radix for input and output. It can be set
592 to 8, 10, or 16. Note that the argument to "radix" is interpreted
593 in the current radix, so "set radix 10" is always a no-op.
595 height N: This integer value is the number of lines on a page. Default
596 is 24, the current `stty rows'' setting, or the ``li#''
597 setting from the termcap entry matching the environment
600 width N: This integer value is the number of characters on a line.
601 Default is 80, the current `stty cols'' setting, or the ``co#''
602 setting from the termcap entry matching the environment
605 Note: ``set screensize'' is obsolete. Use ``set height'' and
606 ``set width'' instead.
608 print address on/off: Print memory addresses in various command displays,
609 such as stack traces and structure values. Gdb looks
610 more ``symbolic'' if you turn this off; it looks more
611 ``machine level'' with it on. Default is ON.
613 print array on/off: Prettyprint arrays. New convenient format! Default
616 print demangle on/off: Print C++ symbols in "source" form if on,
619 print asm-demangle on/off: Same, for assembler level printouts
622 print vtbl on/off: Prettyprint C++ virtual function tables. Default is OFF.
625 * Support for Epoch Environment.
627 The epoch environment is a version of Emacs v18 with windowing. One
628 new command, ``inspect'', is identical to ``print'', except that if you
629 are running in the epoch environment, the value is printed in its own
633 * Support for Shared Libraries
635 GDB can now debug programs and core files that use SunOS shared libraries.
636 Symbols from a shared library cannot be referenced
637 before the shared library has been linked with the program (this
638 happens after you type ``run'' and before the function main() is entered).
639 At any time after this linking (including when examining core files
640 from dynamically linked programs), gdb reads the symbols from each
641 shared library when you type the ``sharedlibrary'' command.
642 It can be abbreviated ``share''.
644 sharedlibrary REGEXP: Load shared object library symbols for files
645 matching a unix regular expression. No argument
646 indicates to load symbols for all shared libraries.
648 info sharedlibrary: Status of loaded shared libraries.
653 A watchpoint stops execution of a program whenever the value of an
654 expression changes. Checking for this slows down execution
655 tremendously whenever you are in the scope of the expression, but is
656 quite useful for catching tough ``bit-spreader'' or pointer misuse
657 problems. Some machines such as the 386 have hardware for doing this
658 more quickly, and future versions of gdb will use this hardware.
660 watch EXP: Set a watchpoint (breakpoint) for an expression.
662 info watchpoints: Information about your watchpoints.
664 delete N: Deletes watchpoint number N (same as breakpoints).
665 disable N: Temporarily turns off watchpoint number N (same as breakpoints).
666 enable N: Re-enables watchpoint number N (same as breakpoints).
669 * C++ multiple inheritance
671 When used with a GCC version 2 compiler, GDB supports multiple inheritance
674 * C++ exception handling
676 Gdb now supports limited C++ exception handling. Besides the existing
677 ability to breakpoint on an exception handler, gdb can breakpoint on
678 the raising of an exception (before the stack is peeled back to the
681 catch FOO: If there is a FOO exception handler in the dynamic scope,
682 set a breakpoint to catch exceptions which may be raised there.
683 Multiple exceptions (``catch foo bar baz'') may be caught.
685 info catch: Lists all exceptions which may be caught in the
689 * Minor command changes
691 The command ``call func (arg, arg, ...)'' now acts like the print
692 command, except it does not print or save a value if the function's result
693 is void. This is similar to dbx usage.
695 The ``up'' and ``down'' commands now always print the frame they end up
696 at; ``up-silently'' and `down-silently'' can be used in scripts to change
697 frames without printing.
699 * New directory command
701 'dir' now adds directories to the FRONT of the source search path.
702 The path starts off empty. Source files that contain debug information
703 about the directory in which they were compiled can be found even
704 with an empty path; Sun CC and GCC include this information. If GDB can't
705 find your source file in the current directory, type "dir .".
707 * Configuring GDB for compilation
709 For normal use, type ``./configure host''. See README or gdb.texinfo
712 GDB now handles cross debugging. If you are remotely debugging between
713 two different machines, type ``./configure host -target=targ''.
714 Host is the machine where GDB will run; targ is the machine
715 where the program that you are debugging will run.
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