gdb/WHATS.NEW

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