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 <a name="Index-Files"></a>
 <div class="header">
 <p>
 Next: <a href="Symbol-Errors.html#Symbol-Errors" accesskey="n" rel="next">Symbol Errors</a>, Previous: <a href="MiniDebugInfo.html#MiniDebugInfo" accesskey="p" rel="prev">MiniDebugInfo</a>, Up: <a href="GDB-Files.html#GDB-Files" accesskey="u" rel="up">GDB Files</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>
 <hr>
 <a name="Index-Files-Speed-Up-GDB"></a>
 <h3 class="section">18.4 Index Files Speed Up <small>GDB</small></h3>
 <a name="index-index-files"></a>
 <a name="index-_002egdb_005findex-section"></a>

 <p>When <small>GDB</small> finds a symbol file, it scans the symbols in the
 file in order to construct an internal symbol table.  This lets most
 <small>GDB</small> operations work quickly&mdash;at the cost of a delay early
 on.  For large programs, this delay can be quite lengthy, so
 <small>GDB</small> provides a way to build an index, which speeds up
 startup.
 </p>
 <p>The index is stored as a section in the symbol file.  <small>GDB</small> can
 write the index to a file, then you can put it into the symbol file
 using <code>objcopy</code>.
 </p>
 <p>To create an index file, use the <code>save gdb-index</code> command:
 </p>
 <dl compact="compact">
 <dt><code>save gdb-index <var>directory</var></code></dt>
 <dd><a name="index-save-gdb_002dindex"></a>
 <p>Create an index file for each symbol file currently known by
 <small>GDB</small>.  Each file is named after its corresponding symbol file,
 with &lsquo;<samp>.gdb-index</samp>&rsquo; appended, and is written into the given
 <var>directory</var>.
 </p></dd>
 </dl>

 <p>Once you have created an index file you can merge it into your symbol
 file, here named <samp>symfile</samp>, using <code>objcopy</code>:
 </p>
 <div class="smallexample">
 <pre class="smallexample">$ objcopy --add-section .gdb_index=symfile.gdb-index \
     --set-section-flags .gdb_index=readonly symfile symfile
 </pre></div>

 <p><small>GDB</small> will normally ignore older versions of <samp>.gdb_index</samp>
 sections that have been deprecated.  Usually they are deprecated because
 they are missing a new feature or have performance issues.
 To tell <small>GDB</small> to use a deprecated index section anyway
 specify <code>set use-deprecated-index-sections on</code>.
 The default is <code>off</code>.
 This can speed up startup, but may result in some functionality being lost.
 See <a href="Index-Section-Format.html#Index-Section-Format">Index Section Format</a>.
 </p>
 <p><em>Warning:</em> Setting <code>use-deprecated-index-sections</code> to <code>on</code>
 must be done before gdb reads the file.  The following will not work:
 </p>
 <div class="smallexample">
 <pre class="smallexample">$ gdb -ex &quot;set use-deprecated-index-sections on&quot; &lt;program&gt;
 </pre></div>

 <p>Instead you must do, for example,
 </p>
 <div class="smallexample">
 <pre class="smallexample">$ gdb -iex &quot;set use-deprecated-index-sections on&quot; &lt;program&gt;
 </pre></div>

 <p>There are currently some limitation on indices.  They only work when
 for DWARF debugging information, not stabs.  And, they do not
 currently work for programs using Ada.
 </p>
 <hr>
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	<a name="Index-Files"></a>
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	<p>
	Next: <a href="Symbol-Errors.html#Symbol-Errors" accesskey="n" rel="next">Symbol Errors</a>, Previous: <a href="MiniDebugInfo.html#MiniDebugInfo" accesskey="p" rel="prev">MiniDebugInfo</a>, Up: <a href="GDB-Files.html#GDB-Files" accesskey="u" rel="up">GDB Files</a>   [<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>
	<hr>
	<a name="Index-Files-Speed-Up-GDB"></a>
	<h3 class="section">18.4 Index Files Speed Up <small>GDB</small></h3>
	<a name="index-index-files"></a>
	<a name="index-_002egdb_005findex-section"></a>

	<p>When <small>GDB</small> finds a symbol file, it scans the symbols in the
	file in order to construct an internal symbol table. This lets most
	<small>GDB</small> operations work quickly—at the cost of a delay early
	on. For large programs, this delay can be quite lengthy, so
	<small>GDB</small> provides a way to build an index, which speeds up
	startup.
	</p>
	<p>The index is stored as a section in the symbol file. <small>GDB</small> can
	write the index to a file, then you can put it into the symbol file
	using <code>objcopy</code>.
	</p>
	<p>To create an index file, use the <code>save gdb-index</code> command:
	</p>
	<dl compact="compact">
	<dt><code>save gdb-index <var>directory</var></code></dt>
	<dd><a name="index-save-gdb_002dindex"></a>
	<p>Create an index file for each symbol file currently known by
	<small>GDB</small>. Each file is named after its corresponding symbol file,
	with ‘<samp>.gdb-index</samp>’ appended, and is written into the given
	<var>directory</var>.
	</p></dd>
	</dl>

	<p>Once you have created an index file you can merge it into your symbol
	file, here named <samp>symfile</samp>, using <code>objcopy</code>:
	</p>
	<div class="smallexample">
	<pre class="smallexample">$ objcopy --add-section .gdb_index=symfile.gdb-index \
	--set-section-flags .gdb_index=readonly symfile symfile
	</pre></div>

	<p><small>GDB</small> will normally ignore older versions of <samp>.gdb_index</samp>
	sections that have been deprecated. Usually they are deprecated because
	they are missing a new feature or have performance issues.
	To tell <small>GDB</small> to use a deprecated index section anyway
	specify <code>set use-deprecated-index-sections on</code>.
	The default is <code>off</code>.
	This can speed up startup, but may result in some functionality being lost.
	See <a href="Index-Section-Format.html#Index-Section-Format">Index Section Format</a>.
	</p>
	<p><em>Warning:</em> Setting <code>use-deprecated-index-sections</code> to <code>on</code>
	must be done before gdb reads the file. The following will not work:
	</p>
	<div class="smallexample">
	<pre class="smallexample">$ gdb -ex "set use-deprecated-index-sections on" <program>
	</pre></div>

	<p>Instead you must do, for example,
	</p>
	<div class="smallexample">
	<pre class="smallexample">$ gdb -iex "set use-deprecated-index-sections on" <program>
	</pre></div>

	<p>There are currently some limitation on indices. They only work when
	for DWARF debugging information, not stabs. And, they do not
	currently work for programs using Ada.
	</p>
	<hr>
	<div class="header">
	<p>
	Next: <a href="Symbol-Errors.html#Symbol-Errors" accesskey="n" rel="next">Symbol Errors</a>, Previous: <a href="MiniDebugInfo.html#MiniDebugInfo" accesskey="p" rel="prev">MiniDebugInfo</a>, Up: <a href="GDB-Files.html#GDB-Files" accesskey="u" rel="up">GDB Files</a>   [<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>
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