gdb/WHATS.NEW

   1                 What has changed since GDB-3.5?
   2                 (Organized release by release)
   3
   4 *** Changes in GDB-4.6:
   5
   6  * Better support for C++ function names
   7
   8 GDB now accepts as input the "demangled form" of C++ overloaded function
   9 names and member function names, and can do command completion on such names
  10 (using TAB, TAB-TAB, and ESC-?).  The names have to be quoted with a pair of
  11 single quotes.  Examples are 'func (int, long)' and 'obj::operator==(obj&)'.
  12 Make use of command completion, it is your friend.
  13
  14 *** Changes in GDB-4.5:
  15
  16  * New machines supported (host and target)
  17
  18 IBM RS6000 running AIX                  rs6000-ibm-aix  or rs6000
  19
  20 SGI Irix-4.x                            mips-sgi-irix4  or iris4
  21
  22  * New malloc package
  23
  24 GDB now uses a new memory manager called mmalloc, based on gmalloc.
  25 Mmalloc is capable of handling mutiple heaps of memory.  It is also
  26 capable of saving a heap to a file, and then mapping it back in later.
  27 This can be used to greatly speedup the startup of GDB by using a
  28 pre-parsed symbol table which lives in a mmalloc managed heap.  For
  29 more details, please read mmalloc/mmalloc.texi.
  30
  31  * info proc
  32
  33 The 'info proc' command (SVR4 only) has been enhanced quite a bit.  See
  34 'help info proc' for details.
  35
  36  * MIPS ecoff symbol table format
  37
  38 The code that reads MIPS symbol table format is now supported on all hosts.
  39 Thanks to MIPS for releasing the sym.h and symconst.h files to make this
  40 possible.
  41
  42  * File name changes for MS-DOS
  43
  44 Many files in the config directories have been renamed to make it easier to
  45 support GDB on MS-DOSe systems (which have very restrictive file name
  46 conventions :-( ).  MS-DOSe host support (under DJ Delorie's GO32
  47 environment) is close to working but has some remaining problems.  Note
  48 that debugging of DOS programs is not supported, due to limitations
  49 in the ``operating system'', but it can be used to host cross-debugging.
  50
  51  * Cross byte order fixes
  52
  53 Many fixes have been made to support cross debugging of Sparc and MIPS
  54 targets from hosts whose byte order differs.
  55
  56  * New -mapped and -readnow options
  57
  58 If memory-mapped files are available on your system through the 'mmap'
  59 system call, you can use the -mapped option on the `file' or
  60 `symbol-file' commands to cause GDB to write the symbols from your
  61 program into a reusable file.  If the program you are debugging is
  62 called `/path/fred', the mapped symbol file will be `./fred.syms'.
  63 Future GDB debugging sessions will notice the presence of this file,
  64 and will quickly map in symbol information from it, rather than reading
  65 the symbol table from the executable program.  Using the '-mapped'
  66 option in a GDB `file' or `symbol-file' command has the same effect as
  67 starting GDB with the '-mapped' command-line option.
  68
  69 You can cause GDB to read the entire symbol table immediately by using
  70 the '-readnow' option with any of the commands that load symbol table
  71 information (or on the GDB command line).  This makes the command
  72 slower, but makes future operations faster.
  73
  74 The -mapped and -readnow options are typically combined in order to
  75 build a `fred.syms' file that contains complete symbol information.
  76 A simple GDB invocation to do nothing but build a `.syms' file for future
  77 use is:
  78
  79         gdb -batch -nx -mapped -readnow programname
  80
  81 The `.syms' file is specific to the host machine on which GDB is run.
  82 It holds an exact image of GDB's internal symbol table.  It cannot be
  83 shared across multiple host platforms.
  84
  85  * longjmp() handling
  86
  87 GDB is now capable of stepping and nexting over longjmp(), _longjmp(), and
  88 siglongjmp() without losing control.  This feature has not yet been ported to
  89 all systems.  It currently works on many 386 platforms, all MIPS-based
  90 platforms (SGI, DECstation, etc), and Sun3/4.
  91
  92  * Solaris 2.0
  93
  94 Preliminary work has been put in to support the new Solaris OS from Sun.  At
  95 this time, it can control and debug processes, but it is not capable of
  96 reading symbols.
  97
  98  * Bug fixes
  99
 100 As always, many many bug fixes.  The major areas were with g++, and mipsread.
 101 People using the MIPS-based platforms should experience fewer mysterious
 102 crashes and trashed symbol tables.
 103
 104 *** Changes in GDB-4.4:
 105
 106  * New machines supported (host and target)
 107
 108 SCO Unix on i386 IBM PC clones          i386-sco-sysv   or  i386sco
 109         (except core files)
 110 BSD Reno on Vax                         vax-dec-bsd
 111 Ultrix on Vax                           vax-dec-ultrix
 112
 113  * New machines supported (target)
 114
 115 AMD 29000 embedded, using EBMON         a29k-none-none
 116
 117  * C++ support
 118
 119 GDB continues to improve its handling of C++.  `References' work better.
 120 The demangler has also been improved, and now deals with symbols mangled as
 121 per the Annotated C++ Reference Guide.
 122
 123 GDB also now handles `stabs' symbol information embedded in MIPS
 124 `ecoff' symbol tables.  Since the ecoff format was not easily
 125 extensible to handle new languages such as C++, this appeared to be a
 126 good way to put C++ debugging info into MIPS binaries.  This option
 127 will be supported in the GNU C compiler, version 2, when it is
 128 released.
 129
 130  * New features for SVR4
 131
 132 GDB now handles SVR4 shared libraries, in the same fashion as SunOS
 133 shared libraries.  Debugging dynamically linked programs should present
 134 only minor differences from debugging statically linked programs.
 135
 136 The `info proc' command will print out information about any process
 137 on an SVR4 system (including the one you are debugging).  At the moment,
 138 it prints the address mappings of the process.
 139
 140 If you bring up GDB on another SVR4 system, please send mail to
 141 bug-gdb@prep.ai.mit.edu to let us know what changes were reqired (if any).
 142
 143  * Better dynamic linking support in SunOS
 144
 145 Reading symbols from shared libraries which contain debugging symbols
 146 now works properly.  However, there remain issues such as automatic
 147 skipping of `transfer vector' code during function calls, which
 148 make it harder to debug code in a shared library, than to debug the
 149 same code linked statically.
 150
 151  * New Getopt
 152
 153 GDB is now using the latest `getopt' routines from the FSF.  This
 154 version accepts the -- prefix for options with long names.  GDB will
 155 continue to accept the old forms (-option and +option) as well.
 156 Various single letter abbreviations for options have been explicity
 157 added to the option table so that they won't get overshadowed in the
 158 future by other options that begin with the same letter.
 159
 160  * Bugs fixed
 161
 162 The `cleanup_undefined_types' bug that many of you noticed has been squashed.
 163 Many assorted bugs have been handled.  Many more remain to be handled.
 164 See the various ChangeLog files (primarily in gdb and bfd) for details.
 165
 166
 167 *** Changes in GDB-4.3:
 168
 169  * New machines supported (host and target)
 170
 171 Amiga 3000 running Amix                 m68k-cbm-svr4   or  amix
 172 NCR 3000 386 running SVR4               i386-ncr-svr4   or  ncr3000
 173 Motorola Delta 88000 running Sys V      m88k-motorola-sysv  or  delta88
 174
 175  * Almost SCO Unix support
 176
 177 We had hoped to support:
 178 SCO Unix on i386 IBM PC clones          i386-sco-sysv   or  i386sco
 179 (except for core file support), but we discovered very late in the release
 180 that it has problems with process groups that render gdb unusable.  Sorry
 181 about that.  I encourage people to fix it and post the fixes.
 182
 183  * Preliminary ELF and DWARF support
 184
 185 GDB can read ELF object files on System V Release 4, and can handle
 186 debugging records for C, in DWARF format, in ELF files.  This support
 187 is preliminary.  If you bring up GDB on another SVR4 system, please
 188 send mail to bug-gdb@prep.ai.mit.edu to let us know what changes were
 189 reqired (if any).
 190
 191  * New Readline
 192
 193 GDB now uses the latest `readline' library.  One user-visible change
 194 is that two tabs will list possible command completions, which previously
 195 required typing M-? (meta-question mark, or ESC ?).
 196
 197  * Bugs fixed
 198
 199 The `stepi' bug that many of you noticed has been squashed.
 200 Many bugs in C++ have been handled.  Many more remain to be handled.
 201 See the various ChangeLog files (primarily in gdb and bfd) for details.
 202
 203  * State of the MIPS world (in case you wondered):
 204
 205 GDB can understand the symbol tables emitted by the compilers
 206 supplied by most vendors of MIPS-based machines, including DEC.  These
 207 symbol tables are in a format that essentially nobody else uses.
 208
 209 Some versions of gcc come with an assembler post-processor called
 210 mips-tfile.  This program is required if you want to do source-level
 211 debugging of gcc-compiled programs.  I believe FSF does not ship
 212 mips-tfile with gcc version 1, but it will eventually come with gcc
 213 version 2.
 214
 215 Debugging of g++ output remains a problem.  g++ version 1.xx does not
 216 really support it at all.  (If you're lucky, you should be able to get
 217 line numbers and stack traces to work, but no parameters or local
 218 variables.)  With some work it should be possible to improve the
 219 situation somewhat.
 220
 221 When gcc version 2 is released, you will have somewhat better luck.
 222 However, even then you will get confusing results for inheritance and
 223 methods.
 224
 225 We will eventually provide full debugging of g++ output on
 226 DECstations.  This will probably involve some kind of stabs-in-ecoff
 227 encapulation, but the details have not been worked out yet.
 228
 229
 230 *** Changes in GDB-4.2:
 231
 232  *  Improved configuration
 233
 234 Only one copy of `configure' exists now, and it is not self-modifying.
 235 Porting BFD is simpler.
 236
 237  *  Stepping improved
 238
 239 The `step' and `next' commands now only stop at the first instruction
 240 of a source line.  This prevents the multiple stops that used to occur
 241 in switch statements, for-loops, etc.  `Step' continues to stop if a
 242 function that has debugging information is called within the line.
 243
 244  *  Bug fixing
 245
 246 Lots of small bugs fixed.  More remain.
 247
 248  *  New host supported (not target)
 249
 250 Intel 386 PC clone running Mach         i386-none-mach
 251
 252
 253 *** Changes in GDB-4.1:
 254
 255  *  Multiple source language support
 256
 257 GDB now has internal scaffolding to handle several source languages.
 258 It determines the type of each source file from its filename extension,
 259 and will switch expression parsing and number formatting to match the
 260 language of the function in the currently selected stack frame.
 261 You can also specifically set the language to be used, with
 262 `set language c' or `set language modula-2'.
 263
 264  *  GDB and Modula-2
 265
 266 GDB now has preliminary support for the GNU Modula-2 compiler,
 267 currently under development at the State University of New York at
 268 Buffalo.  Development of both GDB and the GNU Modula-2 compiler will
 269 continue through the fall of 1991 and into 1992.
 270
 271 Other Modula-2 compilers are currently not supported, and attempting to
 272 debug programs compiled with them will likely result in an error as the
 273 symbol table is read.  Feel free to work on it, though!
 274
 275 There are hooks in GDB for strict type checking and range checking,
 276 in the `Modula-2 philosophy', but they do not currently work.
 277
 278  * set write on/off
 279
 280 GDB can now write to executable and core files (e.g. patch
 281 a variable's value).   You must turn this switch on, specify
 282 the file ("exec foo" or "core foo"), *then* modify it, e.g.
 283 by assigning a new value to a variable.  Modifications take
 284 effect immediately.
 285
 286  * Automatic SunOS shared library reading
 287
 288 When you run your program, GDB automatically determines where its
 289 shared libraries (if any) have been loaded, and reads their symbols.
 290 The `share' command is no longer needed.  This also works when
 291 examining core files.
 292
 293  * set listsize
 294
 295 You can specify the number of lines that the `list' command shows.
 296 The default is 10.
 297
 298  * New machines supported (host and target)
 299
 300 SGI Iris (MIPS) running Irix V3:        mips-sgi-irix   or  iris
 301 Sony NEWS (68K) running NEWSOS 3.x:     m68k-sony-sysv  or  news
 302 Ultracomputer (29K) running Sym1:       a29k-nyu-sym1   or  ultra3
 303
 304  * New hosts supported (not targets)
 305
 306 IBM RT/PC:                              romp-ibm-aix    or  rtpc
 307
 308  * New targets supported (not hosts)
 309
 310 AMD 29000 embedded with COFF            a29k-none-coff
 311 AMD 29000 embedded with a.out           a29k-none-aout
 312 Ultracomputer remote kernel debug       a29k-nyu-kern
 313
 314  * New remote interfaces
 315
 316 AMD 29000 Adapt
 317 AMD 29000 Minimon
 318
 319
 320 *** Changes in GDB-4.0:
 321
 322  *  New Facilities
 323
 324 Wide output is wrapped at good places to make the output more readable.
 325
 326 Gdb now supports cross-debugging from a host machine of one type to a
 327 target machine of another type.  Communication with the target system
 328 is over serial lines.  The ``target'' command handles connecting to the
 329 remote system; the ``load'' command will download a program into the
 330 remote system.  Serial stubs for the m68k and i386 are provided.  Gdb
 331 also supports debugging of realtime processes running under VxWorks,
 332 using SunRPC Remote Procedure Calls over TCP/IP to talk to a debugger
 333 stub on the target system.
 334
 335 New CPUs supported include the AMD 29000 and Intel 960.
 336
 337 GDB now reads object files and symbol tables via a ``binary file''
 338 library, which allows a single copy of GDB to debug programs of multiple
 339 object file types such as a.out and coff.
 340
 341 There is now a GDB reference card in "doc/refcard.tex".  (Make targets
 342 refcard.dvi and refcard.ps are available to format it).
 343
 344
 345  *  Control-Variable user interface simplified
 346
 347 All variables that control the operation of the debugger can be set
 348 by the ``set'' command, and displayed by the ``show'' command.
 349
 350 For example, ``set prompt new-gdb=>'' will change your prompt to new-gdb=>.
 351 ``Show prompt'' produces the response:
 352 Gdb's prompt is new-gdb=>.
 353
 354 What follows are the NEW set commands.  The command ``help set'' will
 355 print a complete list of old and new set commands.  ``help set FOO''
 356 will give a longer description of the variable FOO.  ``show'' will show
 357 all of the variable descriptions and their current settings.
 358
 359 confirm on/off:  Enables warning questions for operations that are
 360                  hard to recover from, e.g. rerunning the program while
 361                  it is already running.  Default is ON.
 362
 363 editing on/off:  Enables EMACS style command line editing
 364                  of input.  Previous lines can be recalled with
 365                  control-P, the current line can be edited with control-B,
 366                  you can search for commands with control-R, etc.
 367                  Default is ON.
 368
 369 history filename NAME:  NAME is where the gdb command history
 370                         will be stored.  The default is .gdb_history,
 371                         or the value of the environment variable
 372                         GDBHISTFILE.
 373
 374 history size N:  The size, in commands, of the command history.  The
 375                  default is 256, or the value of the environment variable
 376                  HISTSIZE.
 377
 378 history save on/off: If this value is set to ON, the history file will
 379                       be saved after exiting gdb.  If set to OFF, the
 380                       file will not be saved.  The default is OFF.
 381
 382 history expansion on/off: If this value is set to ON, then csh-like
 383                           history expansion will be performed  on
 384                           command line input.  The default is OFF.
 385
 386 radix N:  Sets the default radix for input and output.  It can be set
 387           to 8, 10, or 16.  Note that the argument to "radix" is interpreted
 388           in the current radix, so "set radix 10" is always a no-op.
 389
 390 height N: This integer value is the number of lines on a page. Default
 391           is 24, the current `stty rows'' setting, or the ``li#''
 392           setting from the termcap entry matching the environment
 393           variable TERM.
 394
 395 width N:  This integer value is the number of characters on a line.
 396           Default is 80, the current `stty cols'' setting, or the ``co#''
 397           setting from the termcap entry matching the environment
 398           variable TERM.
 399
 400 Note: ``set screensize'' is obsolete. Use ``set height'' and
 401 ``set width'' instead.
 402
 403 print address on/off:  Print memory addresses in various command displays,
 404                       such as stack traces and structure values.  Gdb looks
 405                       more ``symbolic'' if you turn this off; it looks more
 406                       ``machine level'' with it on.  Default is ON.
 407
 408 print array on/off:  Prettyprint arrays.  New convenient format!  Default
 409                     is OFF.
 410
 411 print demangle on/off:   Print C++ symbols in "source" form if on,
 412                         "raw" form if off.
 413
 414 print asm-demangle on/off:  Same, for assembler level printouts
 415                         like instructions.
 416
 417 print vtbl on/off:  Prettyprint C++ virtual function tables.  Default is OFF.
 418
 419
 420  *  Support for Epoch Environment.
 421
 422 The epoch environment is a version of Emacs v18 with windowing.  One
 423 new command, ``inspect'', is identical to ``print'', except that if you
 424 are running in the epoch environment, the value is printed in its own
 425 window.
 426
 427
 428  *  Support for Shared Libraries
 429
 430 GDB can now debug programs and core files that use SunOS shared libraries.
 431 Symbols from a shared library cannot be referenced
 432 before the shared library has been linked with the program (this
 433 happens after you type ``run'' and before the function main() is entered).
 434 At any time after this linking (including when examining core files
 435 from dynamically linked programs), gdb reads the symbols from each
 436 shared library when you type the ``sharedlibrary'' command.
 437 It can be abbreviated ``share''.
 438
 439 sharedlibrary REGEXP:  Load shared object library symbols for files
 440                        matching a unix regular expression.  No argument
 441                        indicates to load symbols for all shared libraries.
 442
 443 info sharedlibrary:  Status of loaded shared libraries.
 444
 445
 446  *  Watchpoints
 447
 448 A watchpoint stops execution of a program whenever the value of an
 449 expression changes.  Checking for this slows down execution
 450 tremendously whenever you are in the scope of the expression, but is
 451 quite useful for catching tough ``bit-spreader'' or pointer misuse
 452 problems.  Some machines such as the 386 have hardware for doing this
 453 more quickly, and future versions of gdb will use this hardware.
 454
 455 watch EXP:  Set a watchpoint (breakpoint) for an expression.
 456
 457 info watchpoints:  Information about your watchpoints.
 458
 459 delete N:   Deletes watchpoint number N (same as breakpoints).
 460 disable N:  Temporarily turns off watchpoint number N (same as breakpoints).
 461 enable N:   Re-enables watchpoint number N (same as breakpoints).
 462
 463
 464  *  C++ multiple inheritance
 465
 466 When used with a GCC version 2 compiler, GDB supports multiple inheritance
 467 for C++ programs.
 468
 469  *  C++ exception handling
 470
 471 Gdb now supports limited C++ exception handling.  Besides the existing
 472 ability to breakpoint on an exception handler, gdb can breakpoint on
 473 the raising of an exception (before the stack is peeled back to the
 474 handler's context).
 475
 476 catch FOO:  If there is a FOO exception handler in the dynamic scope,
 477             set a breakpoint to catch exceptions which may be raised there.
 478             Multiple exceptions (``catch foo bar baz'') may be caught.
 479
 480 info catch:  Lists all exceptions which may be caught in the
 481              current stack frame.
 482
 483
 484  *  Minor command changes
 485
 486 The command ``call func (arg, arg, ...)'' now acts like the print
 487 command, except it does not print or save a value if the function's result
 488 is void.  This is similar to dbx usage.
 489
 490 The ``up'' and ``down'' commands now always print the frame they end up
 491 at; ``up-silently'' and `down-silently'' can be used in scripts to change
 492 frames without printing.
 493
 494  *  New directory command
 495
 496 'dir' now adds directories to the FRONT of the source search path.
 497 The path starts off empty.  Source files that contain debug information
 498 about the directory in which they were compiled can be found even
 499 with an empty path; Sun CC and GCC include this information.  If GDB can't
 500 find your source file in the current directory, type "dir .".
 501
 502  * Configuring GDB for compilation
 503
 504 For normal use, type ``./configure host''.  See README or gdb.texinfo
 505 for more details.
 506
 507 GDB now handles cross debugging.  If you are remotely debugging between
 508 two different machines, type ``./configure host -target=targ''.
 509 Host is the machine where GDB will run; targ is the machine
 510 where the program that you are debugging will run.