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