gdb/WHATS.NEW

   1                 GDB 4.0 -- what has changed since 3.5?
   2
   3  *  New Facilities
   4
   5 Wide output is wrapped at good places to make the output more readable.
   6
   7 Gdb now supports cross-debugging from a host machine of one type to a
   8 target machine of another type.  Communication with the target system
   9 is over serial lines.  The ``target'' command handles connecting to the
  10 remote system; the ``load'' command will download a program into the
  11 remote system.  Serial stubs for the m68k and i386 are provided.  Gdb
  12 also supports debugging of realtime processes running under VxWorks,
  13 using SunRPC Remote Procedure Calls over TCP/IP to talk to a debugger
  14 stub on the target system.
  15
  16 New CPUs supported include the AMD 29000 and Intel 960.
  17
  18 GDB now reads object files and symbol tables via a ``binary file''
  19 library, which allows a single copy of GDB to debug programs of multiple
  20 object file types such as a.out and coff.
  21
  22 There is now a GDB reference card in "doc/refcard.tex".  (Make targets
  23 refcard.dvi and refcard.ps are available to format it).
  24
  25
  26  *  Control-Variable user interface simplified
  27
  28 All variables that control the operation of the debugger can be set
  29 by the ``set'' command, and displayed by the ``show'' command.
  30
  31 For example, ``set prompt new-gdb=>'' will change your prompt to new-gdb=>.
  32 ``Show prompt'' produces the response:
  33 Gdb's prompt is new-gdb=>.
  34
  35 What follows are the NEW set commands.  The command ``help set'' will
  36 print a complete list of old and new set commands.  ``help set FOO''
  37 will give a longer description of the variable FOO.  ``show'' will show
  38 all of the variable descriptions and their current settings.
  39
  40 confirm on/off:  Enables warning questions for operations that are
  41                  hard to recover from, e.g. rerunning the program while
  42                  it is already running.  Default is ON.
  43
  44 editing on/off:  Enables EMACS style command line editing
  45                  of input.  Previous lines can be recalled with
  46                  control-P, the current line can be edited with control-B,
  47                  you can search for commands with control-R, etc.
  48                  Default is ON.
  49
  50 history filename NAME:  NAME is where the gdb command history
  51                         will be stored.  The default is .gdb_history,
  52                         or the value of the environment variable
  53                         GDBHISTFILE.
  54
  55 history size N:  The size, in commands, of the command history.  The
  56                  default is 256, or the value of the environment variable
  57                  HISTSIZE.
  58
  59 history save on/off: If this value is set to ON, the history file will
  60                       be saved after exiting gdb.  If set to OFF, the
  61                       file will not be saved.  The default is OFF.
  62
  63 history expansion on/off: If this value is set to ON, then csh-like
  64                           history expansion will be performed  on
  65                           command line input.  The default is OFF.
  66
  67 radix N:  Sets the default radix for input and output.  It can be set
  68           to 8, 10, or 16.  Note that the argument to "radix" is interpreted
  69           in the current radix, so "set radix 10" is always a no-op.
  70
  71 height N: This integer value is the number of lines on a page. Default
  72           is 24, the current `stty rows'' setting, or the ``li#''
  73           setting from the termcap entry matching the environment
  74           variable TERM.
  75
  76 width N:  This integer value is the number of characters on a line.
  77           Default is 80, the current `stty cols'' setting, or the ``co#''
  78           setting from the termcap entry matching the environment
  79           variable TERM.
  80
  81 Note: ``set screensize'' is obsolete. Use ``set height'' and
  82 ``set width'' instead.
  83
  84 print address on/off:  Print memory addresses in various command displays,
  85                       such as stack traces and structure values.  Gdb looks
  86                       more ``symbolic'' if you turn this off; it looks more
  87                       ``machine level'' with it on.  Default is ON.
  88
  89 print array on/off:  Prettyprint arrays.  New convenient format!  Default
  90                     is OFF.
  91
  92 print demangle on/off:   Print C++ symbols in "source" form if on,
  93                         "raw" form if off.
  94
  95 print asm-demangle on/off:  Same, for assembler level printouts
  96                         like instructions.
  97
  98 print vtbl on/off:  Prettyprint C++ virtual function tables.  Default is OFF.
  99
 100 write on/off:  GDB can now write to executable and core files (e.g. patch
 101                 a variable's value) if you turn this switch on, specify
 102                 the file ("exec foo" or "core foo"), then modify it, e.g.
 103                 by assigning a new value to a variable.
 104
 105  *  Support for Epoch Environment.
 106
 107 The epoch environment is a version of Emacs v18 with windowing.  One
 108 new command, ``inspect'', is identical to ``print'', except that if you
 109 are running in the epoch environment, the value is printed in its own
 110 window.
 111
 112
 113  *  Support for Shared Libraries
 114
 115 GDB can now debug programs and core files that use SunOS shared libraries.
 116 Symbols from a shared library cannot be referenced
 117 before the shared library has been linked with the program (this
 118 happens after you type ``run'' and before the function main() is entered).
 119 At any time after this linking (including when examining core files
 120 from dynamically linked programs), gdb reads the symbols from each
 121 shared library when you type the ``sharedlibrary'' command.
 122 It can be abbreviated ``share''.
 123
 124 sharedlibrary REGEXP:  Load shared object library symbols for files
 125                        matching a unix regular expression.  No argument
 126                        indicates to load symbols for all shared libraries.
 127
 128 info sharedlibrary:  Status of loaded shared libraries.
 129
 130
 131  *  Watchpoints
 132
 133 A watchpoint stops execution of a program whenever the value of an
 134 expression changes.  Checking for this slows down execution
 135 tremendously whenever you are in the scope of the expression, but is
 136 quite useful for catching tough ``bit-spreader'' or pointer misuse
 137 problems.  Some machines such as the 386 have hardware for doing this
 138 more quickly, and future versions of gdb will use this hardware.
 139
 140 watch EXP:  Set a watchpoint (breakpoint) for an expression.
 141
 142 info watchpoints:  Information about your watchpoints.
 143
 144 delete N:   Deletes watchpoint number N (same as breakpoints).
 145 disable N:  Temporarily turns off watchpoint number N (same as breakpoints).
 146 enable N:   Re-enables watchpoint number N (same as breakpoints).
 147
 148
 149  *  C++ multiple inheritance
 150
 151 When used with a GCC version 2 compiler, GDB supports multiple inheritance
 152 for C++ programs.
 153
 154  *  C++ exception handling
 155
 156 Gdb now supports limited C++ exception handling.  Besides the existing
 157 ability to breakpoint on an exception handler, gdb can breakpoint on
 158 the raising of an exception (before the stack is peeled back to the
 159 handler's context).
 160
 161 catch FOO:  If there is a FOO exception handler in the dynamic scope,
 162             set a breakpoint to catch exceptions which may be raised there.
 163             Multiple exceptions (``catch foo bar baz'') may be caught.
 164
 165 info catch:  Lists all exceptions which may be caught in the
 166              current stack frame.
 167
 168
 169  *  Minor command changes
 170
 171 The command ``call func (arg, arg, ...)'' now acts like the print
 172 command, except it does not print or save a value if the function's result
 173 is void.  This is similar to dbx usage.
 174
 175 The ``up'' and ``down'' commands now always print the frame they end up
 176 at; ``up-silently'' and `down-silently'' can be used in scripts to change
 177 frames without printing.
 178
 179  *  New directory command
 180
 181 'dir' now adds directories to the FRONT of the source search path.
 182 The path starts off empty.  Source files that contain debug information
 183 about the directory in which they were compiled can be found even
 184 with an empty path; Sun CC and GCC include this information.  If GDB can't
 185 find your source file in the current directory, type "dir .".
 186
 187  * Configuring GDB for compilation
 188
 189 For normal use, type ``./configure host''.  See README or gdb.texinfo
 190 for more details.
 191
 192 GDB now handles cross debugging.  If you are remotely debugging between
 193 two different machines, type ``./configure host -target=targ''.
 194 Host is the machine where gdb will run; targ is the machine
 195 where the program that you are debugging will run.