In addition to commands intended for gdb users, gdb includes a number of commands intended for gdb developers, that are not documented elsewhere in this manual. These commands are provided here for reference. (For commands that turn on debugging messages, see Debugging Output.)
maint agent [-at location,] expressionmaint agent-eval [-at location,] expressiongloba +
globb will include bytecodes to record four bytes of memory at each
of the addresses of globa and globb, while discarding
the result of the addition, while an evaluation expression will do the
addition and return the sum.
If -at is given, generate remote agent bytecode for location.
If not, generate remote agent bytecode for current frame PC address.
maint agent-printf format,expr,...maint info breakpointsbreakpointwatchpointlongjmplongjmp calls.
longjmp resumelongjmp.
untiluntil command.
finishfinish command.
shlib eventsmaint info btracemaint btrace packet-historybtsptmaint btrace clear-packet-historymaint btrace clearThis implicitly truncates the branch trace to a single branch trace buffer. When updating branch trace incrementally, the branch trace available to gdb may be bigger than a single branch trace buffer.
maint set btrace pt skip-padmaint show btrace pt skip-padset displaced-steppingshow displaced-steppingset displaced-stepping onset displaced-stepping offset displaced-stepping automaint check-psymtabsmaint check-symtabsmaint expand-symtabs [regexp]maint set catch-demangler-crashes [on|off]maint show catch-demangler-crashesmaint cplus first_component namemaint cplus namespacemaint deprecate command [replacement]maint undeprecate commandmaint dump-meSIGQUIT signal.
maint internal-error [message-text]maint internal-warning [message-text]maint demangler-warning [message-text]internal_error,
internal_warning or demangler_warning and hence behave
as though an internal problem has been detected. In addition to
reporting the internal problem, these functions give the user the
opportunity to either quit gdb or (for internal_error
and internal_warning) create a core file of the current
gdb session.
These commands take an optional parameter message-text that is used as the text of the error or warning message.
Here's an example of using internal-error:
(gdb) maint internal-error testing, 1, 2
.../maint.c:121: internal-error: testing, 1, 2
A problem internal to GDB has been detected. Further
debugging may prove unreliable.
Quit this debugging session? (y or n) n
Create a core file? (y or n) n
(gdb)
maint set internal-error action [ask|yes|no]maint show internal-error actionmaint set internal-warning action [ask|yes|no]maint show internal-warning actionmaint set demangler-warning action [ask|yes|no]maint show demangler-warning actioncorefile option for demangler-warning:
demangler warnings always create a core file and this cannot be
disabled.
maint packet textmaint print architecture [file]maint print c-tdescmaint check xml-descriptions dirmaint check libthread-dblibthread_db functionality used by
gdb on GNU/Linux systems, and by extension also exercises the
proc_service functions provided by gdb that
libthread_db uses. Note that parts of the test may be skipped
on some platforms when debugging core files.
maint print dummy-frames (gdb) b add
...
(gdb) print add(2,3)
Breakpoint 2, add (a=2, b=3) at ...
58 return (a + b);
The program being debugged stopped while in a function called from GDB.
...
(gdb) maint print dummy-frames
0xa8206d8: id={stack=0xbfffe734,code=0xbfffe73f,!special}, ptid=process 9353
(gdb)
Takes an optional file parameter.
maint print registers [file]maint print raw-registers [file]maint print cooked-registers [file]maint print register-groups [file]maint print remote-registers [file]The command maint print raw-registers includes the contents of
the raw register cache; the command maint print
cooked-registers includes the (cooked) value of all registers,
including registers which aren't available on the target nor visible
to user; the command maint print register-groups includes the
groups that each register is a member of; and the command maint
print remote-registers includes the remote target's register numbers
and offsets in the `G' packets.
These commands take an optional parameter, a file name to which to write the information.
maint print reggroups [file]The register groups info looks like this:
(gdb) maint print reggroups
Group Type
general user
float user
all user
vector user
system user
save internal
restore internal
flushregsmaint print objfiles [regexp]maint print user-registers$fp, $pc,
$sp, and $ps. See standard registers. User
registers can be used in expressions in the same way as the canonical
register names, but only the latter are listed by the info
registers and maint print registers commands.
maint print section-scripts [regexp].debug_gdb_section section.
If regexp is specified, only print scripts loaded by object files
matching regexp.
For each script, this command prints its name as specified in the objfile,
and the full path if known.
See dotdebug_gdb_scripts section.
maint print statisticsmaint print target-stackThis command prints a short description of each layer that was pushed on the target stack, starting from the top layer down to the bottom one.
maint print type exprmaint selftest [filter]maint info selftestsmaint set dwarf always-disassemblemaint show dwarf always-disassembleinfo address when using DWARF debugging
information.
The default is off, which means that gdb should try to
describe a variable's location in an easily readable format. When
on, gdb will instead display the DWARF location
expression in an assembly-like format. Note that some locations are
too complex for gdb to describe simply; in this case you will
always see the disassembly form.
Here is an example of the resulting disassembly:
(gdb) info addr argc
Symbol "argc" is a complex DWARF expression:
1: DW_OP_fbreg 0
For more information on these expressions, see the DWARF standard.
maint set dwarf max-cache-agemaint show dwarf max-cache-ageIn object files with inter-compilation-unit references, such as those produced by the GCC option ‘-feliminate-dwarf2-dups’, the DWARF reader needs to frequently refer to previously read compilation units. This setting controls how long a compilation unit will remain in the cache if it is not referenced. A higher limit means that cached compilation units will be stored in memory longer, and more total memory will be used. Setting it to zero disables caching, which will slow down gdb startup, but reduce memory consumption.
maint set dwarf unwindersmaint show dwarf unwindersMany targets that support DWARF debugging use gdb's DWARF frame unwinders to build the backtrace. Many of these targets will also have a second mechanism for building the backtrace for use in cases where DWARF information is not available, this second mechanism is often an analysis of a function's prologue.
In order to extend testing coverage of the second level stack unwinding mechanisms it is helpful to be able to disable the DWARF stack unwinders, this can be done with this switch.
In normal use of gdb disabling the DWARF unwinders is not advisable, there are cases that are better handled through DWARF than prologue analysis, and the debug experience is likely to be better with the DWARF frame unwinders enabled.
If DWARF frame unwinders are not supported for a particular target
architecture, then enabling this flag does not cause them to be used.
maint set profilemaint show profileProfiling will be disabled until you use the ‘maint set profile’ command to enable it. When you enable profiling, the system will begin collecting timing and execution count data; when you disable profiling or exit gdb, the results will be written to a log file. Remember that if you use profiling, gdb will overwrite the profiling log file (often called gmon.out). If you have a record of important profiling data in a gmon.out file, be sure to move it to a safe location.
Configuring with ‘--enable-profiling’ arranges for gdb to be compiled with the ‘-pg’ compiler option.
maint set show-debug-regsmaint show show-debug-regson to enable, off to disable. If
enabled, the debug registers values are shown when gdb inserts or
removes a hardware breakpoint or watchpoint, and when the inferior
triggers a hardware-assisted breakpoint or watchpoint.
maint set show-all-tibmaint show show-all-tibmaint set target-asyncmaint show target-asyncmaint set target-non-stopmaint show target-non-stopset non-stop is off (see Non-Stop Mode). The default is auto, meaning non-stop mode is enabled
if supported by the target.
maint set target-non-stop automaint set target-non-stop onmaint set target-non-stop offmaint set per-commandmaint show per-commandmaint set per-command space [on|off]maint show per-command spacemaint set per-command time [on|off]maint show per-command timemaint set per-command symtab [on|off]maint show per-command symtabmaint set check-libthread-db [on|off]maint show check-libthread-dbmaint space valuemaint set per-command space.
A non-zero value enables it, zero disables it.
maint time valuemaint set per-command time.
A non-zero value enables it, zero disables it.
maint translate-address [section] addrinfo address command (see Symbols), except that this
command also allows to find symbols in other sections.
If section was not specified, the section in which the symbol was found is also printed. For dynamically linked executables, the name of executable or shared library containing the symbol is printed as well.
The following command is useful for non-interactive invocations of gdb, such as in the test suite.
set watchdog nsecshow watchdog