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<a name="Maintenance-Commands"></a>
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<hr>
<a name="Maintenance-Commands-1"></a>
<h2 class="appendix">Appendix D Maintenance Commands</h2>
<a name="index-maintenance-commands"></a>
<a name="index-internal-commands"></a>

<p>In addition to commands intended for <small>GDB</small> users, <small>GDB</small>
includes a number of commands intended for <small>GDB</small> developers,
that are not documented elsewhere in this manual.  These commands are
provided here for reference.  (For commands that turn on debugging
messages, see <a href="Debugging-Output.html#Debugging-Output">Debugging Output</a>.)
</p>
<dl compact="compact">
<dd><a name="index-maint-agent"></a>
<a name="index-maint-agent_002deval"></a>
</dd>
<dt><code>maint agent <span class="roman">[</span>-at <var>location</var><span class="roman">,</span><span class="roman">]</span> <var>expression</var></code></dt>
<dt><code>maint agent-eval <span class="roman">[</span>-at <var>location</var><span class="roman">,</span><span class="roman">]</span> <var>expression</var></code></dt>
<dd><p>Translate the given <var>expression</var> into remote agent bytecodes.
This command is useful for debugging the Agent Expression mechanism
(see <a href="Agent-Expressions.html#Agent-Expressions">Agent Expressions</a>).  The &lsquo;<samp>agent</samp>&rsquo; version produces an
expression useful for data collection, such as by tracepoints, while
&lsquo;<samp>maint agent-eval</samp>&rsquo; produces an expression that evaluates directly
to a result.  For instance, a collection expression for <code>globa +
globb</code> will include bytecodes to record four bytes of memory at each
of the addresses of <code>globa</code> and <code>globb</code>, while discarding
the result of the addition, while an evaluation expression will do the
addition and return the sum.
If <code>-at</code> is given, generate remote agent bytecode for <var>location</var>.
If not, generate remote agent bytecode for current frame PC address.
</p>
<a name="index-maint-agent_002dprintf"></a>
</dd>
<dt><code>maint agent-printf <var>format</var>,<var>expr</var>,...</code></dt>
<dd><p>Translate the given format string and list of argument expressions
into remote agent bytecodes and display them as a disassembled list.
This command is useful for debugging the agent version of dynamic
printf (see <a href="Dynamic-printf.html#Dynamic-printf">Dynamic printf</a>).
</p>
<a name="index-maint-info-breakpoints"></a>
</dd>
<dt><code><a name="maint-info-breakpoints"></a>maint info breakpoints</code></dt>
<dd><p>Using the same format as &lsquo;<samp>info breakpoints</samp>&rsquo;, display both the
breakpoints you&rsquo;ve set explicitly, and those <small>GDB</small> is using for
internal purposes.  Internal breakpoints are shown with negative
breakpoint numbers.  The type column identifies what kind of breakpoint
is shown:
</p>
<dl compact="compact">
<dt><code>breakpoint</code></dt>
<dd><p>Normal, explicitly set breakpoint.
</p>
</dd>
<dt><code>watchpoint</code></dt>
<dd><p>Normal, explicitly set watchpoint.
</p>
</dd>
<dt><code>longjmp</code></dt>
<dd><p>Internal breakpoint, used to handle correctly stepping through
<code>longjmp</code> calls.
</p>
</dd>
<dt><code>longjmp resume</code></dt>
<dd><p>Internal breakpoint at the target of a <code>longjmp</code>.
</p>
</dd>
<dt><code>until</code></dt>
<dd><p>Temporary internal breakpoint used by the <small>GDB</small> <code>until</code> command.
</p>
</dd>
<dt><code>finish</code></dt>
<dd><p>Temporary internal breakpoint used by the <small>GDB</small> <code>finish</code> command.
</p>
</dd>
<dt><code>shlib events</code></dt>
<dd><p>Shared library events.
</p>
</dd>
</dl>

<a name="index-maint-info-btrace"></a>
</dd>
<dt><code>maint info btrace</code></dt>
<dd><p>Pint information about raw branch tracing data.
</p>
<a name="index-maint-btrace-packet_002dhistory"></a>
</dd>
<dt><code>maint btrace packet-history</code></dt>
<dd><p>Print the raw branch trace packets that are used to compute the
execution history for the &lsquo;<samp>record btrace</samp>&rsquo; command.  Both the
information and the format in which it is printed depend on the btrace
recording format.
</p>
<dl compact="compact">
<dt><code>bts</code></dt>
<dd><p>For the BTS recording format, print a list of blocks of sequential
code.  For each block, the following information is printed:
</p>
<dl compact="compact">
<dt>Block number</dt>
<dd><p>Newer blocks have higher numbers.  The oldest block has number zero.
</p></dd>
<dt>Lowest &lsquo;<samp>PC</samp>&rsquo;</dt>
<dt>Highest &lsquo;<samp>PC</samp>&rsquo;</dt>
</dl>

</dd>
<dt><code>pt</code></dt>
<dd><p>For the Intel Processor Trace recording format, print a list of
Intel Processor Trace packets.  For each packet, the following
information is printed:
</p>
<dl compact="compact">
<dt>Packet number</dt>
<dd><p>Newer packets have higher numbers.  The oldest packet has number zero.
</p></dd>
<dt>Trace offset</dt>
<dd><p>The packet&rsquo;s offset in the trace stream.
</p></dd>
<dt>Packet opcode and payload</dt>
</dl>
</dd>
</dl>

<a name="index-maint-btrace-clear_002dpacket_002dhistory"></a>
</dd>
<dt><code>maint btrace clear-packet-history</code></dt>
<dd><p>Discards the cached packet history printed by the &lsquo;<samp>maint btrace
packet-history</samp>&rsquo; command.  The history will be computed again when
needed.
</p>
<a name="index-maint-btrace-clear"></a>
</dd>
<dt><code>maint btrace clear</code></dt>
<dd><p>Discard the branch trace data.  The data will be fetched anew and the
branch trace will be recomputed when needed.
</p>
<p>This implicitly truncates the branch trace to a single branch trace
buffer.  When updating branch trace incrementally, the branch trace
available to <small>GDB</small> may be bigger than a single branch trace
buffer.
</p>
<a name="index-maint-set-btrace-pt-skip_002dpad"></a>
</dd>
<dt><code>maint set btrace pt skip-pad</code></dt>
<dd><a name="index-maint-show-btrace-pt-skip_002dpad"></a>
</dd>
<dt><code>maint show btrace pt skip-pad</code></dt>
<dd><p>Control whether <small>GDB</small> will skip PAD packets when computing the
packet history.
</p>
<a name="index-set-displaced_002dstepping"></a>
<a name="index-show-displaced_002dstepping"></a>
<a name="index-displaced-stepping-support"></a>
<a name="index-out_002dof_002dline-single_002dstepping"></a>
</dd>
<dt><code>set displaced-stepping</code></dt>
<dt><code>show displaced-stepping</code></dt>
<dd><p>Control whether or not <small>GDB</small> will do <em>displaced stepping</em>
if the target supports it.  Displaced stepping is a way to single-step
over breakpoints without removing them from the inferior, by executing
an out-of-line copy of the instruction that was originally at the
breakpoint location.  It is also known as out-of-line single-stepping.
</p>
<dl compact="compact">
<dt><code>set displaced-stepping on</code></dt>
<dd><p>If the target architecture supports it, <small>GDB</small> will use
displaced stepping to step over breakpoints.
</p>
</dd>
<dt><code>set displaced-stepping off</code></dt>
<dd><p><small>GDB</small> will not use displaced stepping to step over breakpoints,
even if such is supported by the target architecture.
</p>
<a name="index-non_002dstop-mode_002c-and-set-displaced_002dstepping"></a>
</dd>
<dt><code>set displaced-stepping auto</code></dt>
<dd><p>This is the default mode.  <small>GDB</small> will use displaced stepping
only if non-stop mode is active (see <a href="Non_002dStop-Mode.html#Non_002dStop-Mode">Non-Stop Mode</a>) and the target
architecture supports displaced stepping.
</p></dd>
</dl>

<a name="index-maint-check_002dpsymtabs"></a>
</dd>
<dt><code>maint check-psymtabs</code></dt>
<dd><p>Check the consistency of currently expanded psymtabs versus symtabs.
Use this to check, for example, whether a symbol is in one but not the other.
</p>
<a name="index-maint-check_002dsymtabs"></a>
</dd>
<dt><code>maint check-symtabs</code></dt>
<dd><p>Check the consistency of currently expanded symtabs.
</p>
<a name="index-maint-expand_002dsymtabs"></a>
</dd>
<dt><code>maint expand-symtabs [<var>regexp</var>]</code></dt>
<dd><p>Expand symbol tables.
If <var>regexp</var> is specified, only expand symbol tables for file
names matching <var>regexp</var>.
</p>
<a name="index-maint-set-catch_002ddemangler_002dcrashes"></a>
<a name="index-maint-show-catch_002ddemangler_002dcrashes"></a>
<a name="index-demangler-crashes"></a>
</dd>
<dt><code>maint set catch-demangler-crashes [on|off]</code></dt>
<dt><code>maint show catch-demangler-crashes</code></dt>
<dd><p>Control whether <small>GDB</small> should attempt to catch crashes in the
symbol name demangler.  The default is to attempt to catch crashes.
If enabled, the first time a crash is caught, a core file is created,
the offending symbol is displayed and the user is presented with the
option to terminate the current session.
</p>
<a name="index-maint-cplus-first_005fcomponent"></a>
</dd>
<dt><code>maint cplus first_component <var>name</var></code></dt>
<dd><p>Print the first C<tt>++</tt> class/namespace component of <var>name</var>.
</p>
<a name="index-maint-cplus-namespace"></a>
</dd>
<dt><code>maint cplus namespace</code></dt>
<dd><p>Print the list of possible C<tt>++</tt> namespaces.
</p>
<a name="index-maint-deprecate"></a>
<a name="index-maint-undeprecate"></a>
<a name="index-deprecated-commands"></a>
</dd>
<dt><code>maint deprecate <var>command</var> <span class="roman">[</span><var>replacement</var><span class="roman">]</span></code></dt>
<dt><code>maint undeprecate <var>command</var></code></dt>
<dd><p>Deprecate or undeprecate the named <var>command</var>.  Deprecated commands
cause <small>GDB</small> to issue a warning when you use them.  The optional
argument <var>replacement</var> says which newer command should be used in
favor of the deprecated one; if it is given, <small>GDB</small> will mention
the replacement as part of the warning.
</p>
<a name="index-maint-dump_002dme"></a>
</dd>
<dt><code>maint dump-me</code></dt>
<dd><a name="index-SIGQUIT-signal_002c-dump-core-of-GDB"></a>
<p>Cause a fatal signal in the debugger and force it to dump its core.
This is supported only on systems which support aborting a program
with the <code>SIGQUIT</code> signal.
</p>
<a name="index-maint-internal_002derror"></a>
<a name="index-maint-internal_002dwarning"></a>
<a name="index-maint-demangler_002dwarning"></a>
<a name="index-demangler-crashes-1"></a>
</dd>
<dt><code>maint internal-error <span class="roman">[</span><var>message-text</var><span class="roman">]</span></code></dt>
<dt><code>maint internal-warning <span class="roman">[</span><var>message-text</var><span class="roman">]</span></code></dt>
<dt><code>maint demangler-warning <span class="roman">[</span><var>message-text</var><span class="roman">]</span></code></dt>
<dd>
<p>Cause <small>GDB</small> to call the internal function <code>internal_error</code>,
<code>internal_warning</code> or <code>demangler_warning</code> 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 <small>GDB</small> or (for <code>internal_error</code>
and <code>internal_warning</code>) create a core file of the current
<small>GDB</small> session.
</p>
<p>These commands take an optional parameter <var>message-text</var> that is
used as the text of the error or warning message.
</p>
<p>Here&rsquo;s an example of using <code>internal-error</code>:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) <kbd>maint internal-error testing, 1, 2</kbd>
&hellip;/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) <kbd>n</kbd>
Create a core file? (y or n) <kbd>n</kbd>
(gdb)
</pre></div>

<a name="index-GDB-internal-error"></a>
<a name="index-internal-errors_002c-control-of-GDB-behavior"></a>
<a name="index-demangler-crashes-2"></a>

<a name="index-maint-set-internal_002derror"></a>
<a name="index-maint-show-internal_002derror"></a>
<a name="index-maint-set-internal_002dwarning"></a>
<a name="index-maint-show-internal_002dwarning"></a>
<a name="index-maint-set-demangler_002dwarning"></a>
<a name="index-maint-show-demangler_002dwarning"></a>
</dd>
<dt><code>maint set internal-error <var>action</var> [ask|yes|no]</code></dt>
<dt><code>maint show internal-error <var>action</var></code></dt>
<dt><code>maint set internal-warning <var>action</var> [ask|yes|no]</code></dt>
<dt><code>maint show internal-warning <var>action</var></code></dt>
<dt><code>maint set demangler-warning <var>action</var> [ask|yes|no]</code></dt>
<dt><code>maint show demangler-warning <var>action</var></code></dt>
<dd><p>When <small>GDB</small> reports an internal problem (error or warning) it
gives the user the opportunity to both quit <small>GDB</small> and create a
core file of the current <small>GDB</small> session.  These commands let you
override the default behaviour for each particular <var>action</var>,
described in the table below.
</p>
<dl compact="compact">
<dt>&lsquo;<samp>quit</samp>&rsquo;</dt>
<dd><p>You can specify that <small>GDB</small> should always (yes) or never (no)
quit.  The default is to ask the user what to do.
</p>
</dd>
<dt>&lsquo;<samp>corefile</samp>&rsquo;</dt>
<dd><p>You can specify that <small>GDB</small> should always (yes) or never (no)
create a core file.  The default is to ask the user what to do.  Note
that there is no <code>corefile</code> option for <code>demangler-warning</code>:
demangler warnings always create a core file and this cannot be
disabled.
</p></dd>
</dl>

<a name="index-maint-packet"></a>
</dd>
<dt><code>maint packet <var>text</var></code></dt>
<dd><p>If <small>GDB</small> is talking to an inferior via the serial protocol,
then this command sends the string <var>text</var> to the inferior, and
displays the response packet.  <small>GDB</small> supplies the initial
&lsquo;<samp>$</samp>&rsquo; character, the terminating &lsquo;<samp>#</samp>&rsquo; character, and the
checksum.
</p>
<a name="index-maint-print-architecture"></a>
</dd>
<dt><code>maint print architecture <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dd><p>Print the entire architecture configuration.  The optional argument
<var>file</var> names the file where the output goes.
</p>
<a name="index-maint-print-c_002dtdesc-_005bfile_005d"></a>
</dd>
<dt><code>maint print c-tdesc</code></dt>
<dd><p>Print the target description (see <a href="Target-Descriptions.html#Target-Descriptions">Target Descriptions</a>) as
a C source file.  By default, the target description is for the current
target, but if the optional argument <var>file</var> is provided, that file
is used to produce the description.  The <var>file</var> should be an XML
document, of the form described in <a href="Target-Description-Format.html#Target-Description-Format">Target Description Format</a>.
The created source file is built into <small>GDB</small> when <small>GDB</small> is
built again.  This command is used by developers after they add or
modify XML target descriptions.
</p>
<a name="index-maint-print-xml_002dtdesc"></a>
</dd>
<dt><code>maint print xml-tdesc  <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dd><p>Print the target description (see <a href="Target-Descriptions.html#Target-Descriptions">Target Descriptions</a>) as an XML
file.  By default print the target description for the current target,
but if the optional argument <var>file</var> is provided, then that file is
read in by GDB and then used to produce the description.  The
<var>file</var> should be an XML document, of the form described in
<a href="Target-Description-Format.html#Target-Description-Format">Target Description Format</a>.
</p>
<a name="index-maint-check-xml_002ddescriptions"></a>
</dd>
<dt><code>maint check xml-descriptions <var>dir</var></code></dt>
<dd><p>Check that the target descriptions dynamically created by <small>GDB</small>
equal the descriptions created from XML files found in <var>dir</var>.
</p>
<a name="maint-check-libthread_002ddb"></a><a name="index-maint-check-libthread_002ddb"></a>
</dd>
<dt><code>maint check libthread-db</code></dt>
<dd><p>Run integrity checks on the current inferior&rsquo;s thread debugging
library.  This exercises all <code>libthread_db</code> functionality used by
<small>GDB</small> on GNU/Linux systems, and by extension also exercises the
<code>proc_service</code> functions provided by <small>GDB</small> that
<code>libthread_db</code> uses.  Note that parts of the test may be skipped
on some platforms when debugging core files.
</p>
<a name="index-maint-print-core_002dfile_002dbacked_002dmappings"></a>
<a name="index-memory-address-space-mappings-1"></a>
</dd>
<dt><code>maint print core-file-backed-mappings</code></dt>
<dd><p>Print the file-backed mappings which were loaded from a core file note.
This output represents state internal to <small>GDB</small> and should be
similar to the mappings displayed by the <code>info proc mappings</code>
command.
</p>
<a name="index-maint-print-dummy_002dframes"></a>
</dd>
<dt><code>maint print dummy-frames</code></dt>
<dd><p>Prints the contents of <small>GDB</small>&rsquo;s internal dummy-frame stack.
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) <kbd>b add</kbd>
&hellip;
(gdb) <kbd>print add(2,3)</kbd>
Breakpoint 2, add (a=2, b=3) at &hellip;
58	  return (a + b);
The program being debugged stopped while in a function called from GDB.
&hellip;
(gdb) <kbd>maint print dummy-frames</kbd>
0xa8206d8: id={stack=0xbfffe734,code=0xbfffe73f,!special}, ptid=process 9353
(gdb)
</pre></div>

<p>Takes an optional file parameter.
</p>
<a name="index-maint-print-registers"></a>
<a name="index-maint-print-raw_002dregisters"></a>
<a name="index-maint-print-cooked_002dregisters"></a>
<a name="index-maint-print-register_002dgroups"></a>
<a name="index-maint-print-remote_002dregisters"></a>
</dd>
<dt><code>maint print registers <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dt><code>maint print raw-registers <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dt><code>maint print cooked-registers <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dt><code>maint print register-groups <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dt><code>maint print remote-registers <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dd><p>Print <small>GDB</small>&rsquo;s internal register data structures.
</p>
<p>The command <code>maint print raw-registers</code> includes the contents of
the raw register cache; the command <code>maint print
cooked-registers</code> includes the (cooked) value of all registers,
including registers which aren&rsquo;t available on the target nor visible
to user; the command <code>maint print register-groups</code> includes the
groups that each register is a member of; and the command <code>maint
print remote-registers</code> includes the remote target&rsquo;s register numbers
and offsets in the &lsquo;G&rsquo; packets.
</p>
<p>These commands take an optional parameter, a file name to which to
write the information.
</p>
<a name="index-maint-print-reggroups"></a>
</dd>
<dt><code>maint print reggroups <span class="roman">[</span><var>file</var><span class="roman">]</span></code></dt>
<dd><p>Print <small>GDB</small>&rsquo;s internal register group data structures.  The
optional argument <var>file</var> tells to what file to write the
information.
</p>
<p>The register groups info looks like this:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) <kbd>maint print reggroups</kbd>
 Group      Type
 general    user
 float      user
 all        user
 vector     user
 system     user
 save       internal
 restore    internal
</pre></div>

<a name="index-flushregs"></a>
</dd>
<dt><code>flushregs</code></dt>
<dd><p>This command forces <small>GDB</small> to flush its internal register cache.
</p>
<a name="index-maint-print-objfiles"></a>
<a name="index-info-for-known-object-files"></a>
</dd>
<dt><code>maint print objfiles <span class="roman">[</span><var>regexp</var><span class="roman">]</span></code></dt>
<dd><p>Print a dump of all known object files.
If <var>regexp</var> is specified, only print object files whose names
match <var>regexp</var>.  For each object file, this command prints its name,
address in memory, and all of its psymtabs and symtabs.
</p>
<a name="index-maint-print-user_002dregisters"></a>
<a name="index-user-registers"></a>
</dd>
<dt><code>maint print user-registers</code></dt>
<dd><p>List all currently available <em>user registers</em>.  User registers
typically provide alternate names for actual hardware registers.  They
include the four &ldquo;standard&rdquo; registers <code>$fp</code>, <code>$pc</code>,
<code>$sp</code>, and <code>$ps</code>.  See <a href="Registers.html#standard-registers">standard registers</a>.  User
registers can be used in expressions in the same way as the canonical
register names, but only the latter are listed by the <code>info
registers</code> and <code>maint print registers</code> commands.
</p>
<a name="index-maint-print-section_002dscripts"></a>
<a name="index-info-for-known-_002edebug_005fgdb_005fscripts_002dloaded-scripts"></a>
</dd>
<dt><code>maint print section-scripts [<var>regexp</var>]</code></dt>
<dd><p>Print a dump of scripts specified in the <code>.debug_gdb_section</code> section.
If <var>regexp</var> is specified, only print scripts loaded by object files
matching <var>regexp</var>.
For each script, this command prints its name as specified in the objfile,
and the full path if known.
See <a href="dotdebug_005fgdb_005fscripts-section.html#dotdebug_005fgdb_005fscripts-section">dotdebug_gdb_scripts section</a>.
</p>
<a name="index-maint-print-statistics"></a>
<a name="index-bcache-statistics"></a>
</dd>
<dt><code>maint print statistics</code></dt>
<dd><p>This command prints, for each object file in the program, various data
about that object file followed by the byte cache (<em>bcache</em>)
statistics for the object file.  The objfile data includes the number
of minimal, partial, full, and stabs symbols, the number of types
defined by the objfile, the number of as yet unexpanded psym tables,
the number of line tables and string tables, and the amount of memory
used by the various tables.  The bcache statistics include the counts,
sizes, and counts of duplicates of all and unique objects, max,
average, and median entry size, total memory used and its overhead and
savings, and various measures of the hash table size and chain
lengths.
</p>
<a name="index-maint-print-target_002dstack"></a>
<a name="index-target-stack-description"></a>
</dd>
<dt><code>maint print target-stack</code></dt>
<dd><p>A <em>target</em> is an interface between the debugger and a particular
kind of file or process.  Targets can be stacked in <em>strata</em>,
so that more than one target can potentially respond to a request.
In particular, memory accesses will walk down the stack of targets
until they find a target that is interested in handling that particular
address.
</p>
<p>This command prints a short description of each layer that was pushed on
the <em>target stack</em>, starting from the top layer down to the bottom one.
</p>
<a name="index-maint-print-type"></a>
<a name="index-type-chain-of-a-data-type"></a>
</dd>
<dt><code>maint print type <var>expr</var></code></dt>
<dd><p>Print the type chain for a type specified by <var>expr</var>.  The argument
can be either a type name or a symbol.  If it is a symbol, the type of
that symbol is described.  The type chain produced by this command is
a recursive definition of the data type as stored in <small>GDB</small>&rsquo;s
data structures, including its flags and contained types.
</p>
<a name="index-maint-selftest"></a>
<a name="index-self-tests"></a>
</dd>
<dt><code>maint selftest <span class="roman">[</span><var>filter</var><span class="roman">]</span></code></dt>
<dd><p>Run any self tests that were compiled in to <small>GDB</small>.  This will
print a message showing how many tests were run, and how many failed.
If a <var>filter</var> is passed, only the tests with <var>filter</var> in their
name will by ran.
</p>
<a name="index-maint-info-selftests"></a>
<a name="index-self-tests-1"></a>
</dd>
<dt><code>maint info selftests</code></dt>
<dd><p>List the selftests compiled in to <small>GDB</small>.
</p>
<a name="index-maint-set-dwarf-always_002ddisassemble"></a>
<a name="index-maint-show-dwarf-always_002ddisassemble"></a>
</dd>
<dt><code>maint set dwarf always-disassemble</code></dt>
<dt><code>maint show dwarf always-disassemble</code></dt>
<dd><p>Control the behavior of <code>info address</code> when using DWARF debugging
information.
</p>
<p>The default is <code>off</code>, which means that <small>GDB</small> should try to
describe a variable&rsquo;s location in an easily readable format.  When
<code>on</code>, <small>GDB</small> will instead display the DWARF location
expression in an assembly-like format.  Note that some locations are
too complex for <small>GDB</small> to describe simply; in this case you will
always see the disassembly form.
</p>
<p>Here is an example of the resulting disassembly:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) info addr argc
Symbol &quot;argc&quot; is a complex DWARF expression:
     1: DW_OP_fbreg 0
</pre></div>

<p>For more information on these expressions, see
<a href="http://www.dwarfstd.org/">the DWARF standard</a>.
</p>
<a name="index-maint-set-dwarf-max_002dcache_002dage"></a>
<a name="index-maint-show-dwarf-max_002dcache_002dage"></a>
</dd>
<dt><code>maint set dwarf max-cache-age</code></dt>
<dt><code>maint show dwarf max-cache-age</code></dt>
<dd><p>Control the DWARF compilation unit cache.
</p>
<a name="index-DWARF-compilation-units-cache"></a>
<p>In object files with inter-compilation-unit references, such as those
produced by the GCC option &lsquo;<samp>-feliminate-dwarf2-dups</samp>&rsquo;, 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 <small>GDB</small> startup, but reduce memory consumption.
</p>
<a name="index-maint-set-dwarf-unwinders"></a>
<a name="index-maint-show-dwarf-unwinders"></a>
</dd>
<dt><code>maint set dwarf unwinders</code></dt>
<dt><code>maint show dwarf unwinders</code></dt>
<dd><p>Control use of the DWARF frame unwinders.
</p>
<a name="index-DWARF-frame-unwinders"></a>
<p>Many targets that support DWARF debugging use <small>GDB</small>&rsquo;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&rsquo;s prologue.
</p>
<p>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.
</p>
<p>In normal use of <small>GDB</small> 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.
</p>
<p>If DWARF frame unwinders are not supported for a particular target
architecture, then enabling this flag does not cause them to be used.
</p>
<a name="index-maint-set-worker_002dthreads"></a>
<a name="index-maint-show-worker_002dthreads"></a>
</dd>
<dt><code>maint set worker-threads</code></dt>
<dt><code>maint show worker-threads</code></dt>
<dd><p>Control the number of worker threads that may be used by <small>GDB</small>.
On capable hosts, <small>GDB</small> may use multiple threads to speed up
certain CPU-intensive operations, such as demangling symbol names.
While the number of threads used by <small>GDB</small> may vary, this
command can be used to set an upper bound on this number.  The default
is <code>unlimited</code>, which lets <small>GDB</small> choose a reasonable
number.  Note that this only controls worker threads started by
<small>GDB</small> itself; libraries used by <small>GDB</small> may start threads
of their own.
</p>
<a name="index-maint-set-profile"></a>
<a name="index-maint-show-profile"></a>
<a name="index-profiling-GDB"></a>
</dd>
<dt><code>maint set profile</code></dt>
<dt><code>maint show profile</code></dt>
<dd><p>Control profiling of <small>GDB</small>.
</p>
<p>Profiling will be disabled until you use the &lsquo;<samp>maint set profile</samp>&rsquo;
command to enable it.  When you enable profiling, the system will begin
collecting timing and execution count data; when you disable profiling or
exit <small>GDB</small>, the results will be written to a log file.  Remember that
if you use profiling, <small>GDB</small> will overwrite the profiling log file
(often called <samp>gmon.out</samp>).  If you have a record of important profiling
data in a <samp>gmon.out</samp> file, be sure to move it to a safe location.
</p>
<p>Configuring with &lsquo;<samp>--enable-profiling</samp>&rsquo; arranges for <small>GDB</small> to be
compiled with the &lsquo;<samp>-pg</samp>&rsquo; compiler option.
</p>
<a name="index-maint-set-show_002ddebug_002dregs"></a>
<a name="index-maint-show-show_002ddebug_002dregs"></a>
<a name="index-hardware-debug-registers"></a>
</dd>
<dt><code>maint set show-debug-regs</code></dt>
<dt><code>maint show show-debug-regs</code></dt>
<dd><p>Control whether to show variables that mirror the hardware debug
registers.  Use <code>on</code> to enable, <code>off</code> to disable.  If
enabled, the debug registers values are shown when <small>GDB</small> inserts or
removes a hardware breakpoint or watchpoint, and when the inferior
triggers a hardware-assisted breakpoint or watchpoint.
</p>
<a name="index-maint-set-show_002dall_002dtib"></a>
<a name="index-maint-show-show_002dall_002dtib"></a>
</dd>
<dt><code>maint set show-all-tib</code></dt>
<dt><code>maint show show-all-tib</code></dt>
<dd><p>Control whether to show all non zero areas within a 1k block starting
at thread local base, when using the &lsquo;<samp>info w32 thread-information-block</samp>&rsquo;
command.
</p>
<a name="index-maint-set-target_002dasync"></a>
<a name="index-maint-show-target_002dasync"></a>
</dd>
<dt><code>maint set target-async</code></dt>
<dt><code>maint show target-async</code></dt>
<dd><p>This controls whether <small>GDB</small> targets operate in synchronous or
asynchronous mode (see <a href="Background-Execution.html#Background-Execution">Background Execution</a>).  Normally the
default is asynchronous, if it is available; but this can be changed
to more easily debug problems occurring only in synchronous mode.
</p>
<a name="index-maint-set-target_002dnon_002dstop-mode-_005bon_007coff_007cauto_005d"></a>
<a name="index-maint-show-target_002dnon_002dstop"></a>
</dd>
<dt><code>maint set target-non-stop</code></dt>
<dt><code>maint show target-non-stop</code></dt>
<dd>
<p>This controls whether <small>GDB</small> targets always operate in non-stop
mode even if <code>set non-stop</code> is <code>off</code> (see <a href="Non_002dStop-Mode.html#Non_002dStop-Mode">Non-Stop Mode</a>).  The default is <code>auto</code>, meaning non-stop mode is enabled
if supported by the target.
</p>
<dl compact="compact">
<dt><code>maint set target-non-stop auto</code></dt>
<dd><p>This is the default mode.  <small>GDB</small> controls the target in
non-stop mode if the target supports it.
</p>
</dd>
<dt><code>maint set target-non-stop on</code></dt>
<dd><p><small>GDB</small> controls the target in non-stop mode even if the target
does not indicate support.
</p>
</dd>
<dt><code>maint set target-non-stop off</code></dt>
<dd><p><small>GDB</small> does not control the target in non-stop mode even if the
target supports it.
</p></dd>
</dl>

<a name="index-maint-set-tui_002dresize_002dmessage"></a>
<a name="index-maint-show-tui_002dresize_002dmessage"></a>
</dd>
<dt><code>maint set tui-resize-message</code></dt>
<dt><code>maint show tui-resize-message</code></dt>
<dd><p>Control whether <small>GDB</small> displays a message each time the terminal
is resized when in TUI mode.  The default is <code>off</code>, which means
that <small>GDB</small> is silent during resizes.  When <code>on</code>,
<small>GDB</small> will display a message after a resize is completed; the
message will include a number indicating how many times the terminal
has been resized.  This setting is intended for use by the test suite,
where it would otherwise be difficult to determine when a resize and
refresh has been completed.
</p>
<a name="index-maint-set-per_002dcommand"></a>
<a name="index-maint-show-per_002dcommand"></a>
</dd>
<dt><code>maint set per-command</code></dt>
<dt><code>maint show per-command</code></dt>
<dd><a name="index-resources-used-by-commands"></a>

<p><small>GDB</small> can display the resources used by each command.
This is useful in debugging performance problems.
</p>
<dl compact="compact">
<dt><code>maint set per-command space [on|off]</code></dt>
<dt><code>maint show per-command space</code></dt>
<dd><p>Enable or disable the printing of the memory used by GDB for each command.
If enabled, <small>GDB</small> will display how much memory each command
took, following the command&rsquo;s own output.
This can also be requested by invoking <small>GDB</small> with the
<samp>--statistics</samp> command-line switch (see <a href="Mode-Options.html#Mode-Options">Mode Options</a>).
</p>
</dd>
<dt><code>maint set per-command time [on|off]</code></dt>
<dt><code>maint show per-command time</code></dt>
<dd><p>Enable or disable the printing of the execution time of <small>GDB</small>
for each command.
If enabled, <small>GDB</small> will display how much time it
took to execute each command, following the command&rsquo;s own output.
Both CPU time and wallclock time are printed.
Printing both is useful when trying to determine whether the cost is
CPU or, e.g., disk/network latency.
Note that the CPU time printed is for <small>GDB</small> only, it does not include
the execution time of the inferior because there&rsquo;s no mechanism currently
to compute how much time was spent by <small>GDB</small> and how much time was
spent by the program been debugged.
This can also be requested by invoking <small>GDB</small> with the
<samp>--statistics</samp> command-line switch (see <a href="Mode-Options.html#Mode-Options">Mode Options</a>).
</p>
</dd>
<dt><code>maint set per-command symtab [on|off]</code></dt>
<dt><code>maint show per-command symtab</code></dt>
<dd><p>Enable or disable the printing of basic symbol table statistics
for each command.
If enabled, <small>GDB</small> will display the following information:
</p>
<ol>
<li> number of symbol tables
</li><li> number of primary symbol tables
</li><li> number of blocks in the blockvector
</li></ol>
</dd>
</dl>

<a name="index-maint-set-check_002dlibthread_002ddb"></a>
<a name="index-maint-show-check_002dlibthread_002ddb"></a>
</dd>
<dt><code>maint set check-libthread-db [on|off]</code></dt>
<dt><code>maint show check-libthread-db</code></dt>
<dd><p>Control whether <small>GDB</small> should run integrity checks on inferior
specific thread debugging libraries as they are loaded.  The default
is not to perform such checks.  If any check fails <small>GDB</small> will
unload the library and continue searching for a suitable candidate as
described in <a href="Threads.html#set-libthread_002ddb_002dsearch_002dpath">set libthread-db-search-path</a>.  For more information
about the tests, see <a href="#maint-check-libthread_002ddb">maint check libthread-db</a>.
</p>
<a name="index-maint-space"></a>
<a name="index-memory-used-by-commands"></a>
</dd>
<dt><code>maint space <var>value</var></code></dt>
<dd><p>An alias for <code>maint set per-command space</code>.
A non-zero value enables it, zero disables it.
</p>
<a name="index-maint-time"></a>
<a name="index-time-of-command-execution"></a>
</dd>
<dt><code>maint time <var>value</var></code></dt>
<dd><p>An alias for <code>maint set per-command time</code>.
A non-zero value enables it, zero disables it.
</p>
<a name="index-maint-translate_002daddress"></a>
</dd>
<dt><code>maint translate-address <span class="roman">[</span><var>section</var><span class="roman">]</span> <var>addr</var></code></dt>
<dd><p>Find the symbol stored at the location specified by the address
<var>addr</var> and an optional section name <var>section</var>.  If found,
<small>GDB</small> prints the name of the closest symbol and an offset from
the symbol&rsquo;s location to the specified address.  This is similar to
the <code>info address</code> command (see <a href="Symbols.html#Symbols">Symbols</a>), except that this
command also allows to find symbols in other sections.
</p>
<p>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.
</p>
<a name="index-maint-test_002doptions"></a>
</dd>
<dt><code>maint test-options require-delimiter</code></dt>
<dt><code>maint test-options unknown-is-error</code></dt>
<dt><code>maint test-options unknown-is-operand</code></dt>
<dd><p>These commands are used by the testsuite to validate the command
options framework.  The <code>require-delimiter</code> variant requires a
double-dash delimiter to indicate end of options.  The
<code>unknown-is-error</code> and <code>unknown-is-operand</code> do not.  The
<code>unknown-is-error</code> variant throws an error on unknown option,
while <code>unknown-is-operand</code> treats unknown options as the start of
the command&rsquo;s operands.  When run, the commands output the result of
the processed options.  When completed, the commands store the
internal result of completion in a variable exposed by the <code>maint
show test-options-completion-result</code> command.
</p>
<a name="index-maint-show-test_002doptions_002dcompletion_002dresult"></a>
</dd>
<dt><code>maint show test-options-completion-result</code></dt>
<dd><p>Shows the result of completing the <code>maint test-options</code>
subcommands.  This is used by the testsuite to validate completion
support in the command options framework.
</p>
<a name="index-maint-set-test_002dsettings"></a>
<a name="index-maint-show-test_002dsettings"></a>
</dd>
<dt><code>maint set test-settings <var>kind</var></code></dt>
<dt><code>maint show test-settings <var>kind</var></code></dt>
<dd><p>These are representative commands for each <var>kind</var> of setting type
<small>GDB</small> supports.  They are used by the testsuite for exercising
the settings infrastructure.
</p>
<a name="index-maint-with"></a>
</dd>
<dt><code>maint with <var>setting</var> [<var>value</var>] [-- <var>command</var>]</code></dt>
<dd><p>Like the <code>with</code> command, but works with <code>maintenance set</code>
variables.  This is used by the testsuite to exercise the <code>with</code>
command&rsquo;s infrastructure.
</p>
</dd>
</dl>

<p>The following command is useful for non-interactive invocations of
<small>GDB</small>, such as in the test suite.
</p>
<dl compact="compact">
<dt><code>set watchdog <var>nsec</var></code></dt>
<dd><a name="index-set-watchdog"></a>
<a name="index-watchdog-timer"></a>
<a name="index-timeout-for-commands"></a>
<p>Set the maximum number of seconds <small>GDB</small> will wait for the
target operation to finish.  If this time expires, <small>GDB</small>
reports and error and the command is aborted.
</p>
</dd>
<dt><code>show watchdog</code></dt>
<dd><p>Show the current setting of the target wait timeout.
</p></dd>
</dl>

<hr>
<div class="header">
<p>
Next: <a href="Remote-Protocol.html#Remote-Protocol" accesskey="n" rel="next">Remote Protocol</a>, Previous: <a href="Installing-GDB.html#Installing-GDB" accesskey="p" rel="previous">Installing GDB</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>


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