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<h2 class="chapter">19 Makefile Fragments</h2>
<p><a name="index-makefile-fragment-5052"></a>
When you configure GCC using the <samp><span class="file">configure</span></samp> script, it will
construct the file <samp><span class="file">Makefile</span></samp> from the template file
<samp><span class="file">Makefile.in</span></samp>. When it does this, it can incorporate makefile
fragments from the <samp><span class="file">config</span></samp> directory. These are used to set
Makefile parameters that are not amenable to being calculated by
autoconf. The list of fragments to incorporate is set by
<samp><span class="file">config.gcc</span></samp> (and occasionally <samp><span class="file">config.build</span></samp>
and <samp><span class="file">config.host</span></samp>); See <a href="System-Config.html#System-Config">System Config</a>.
<p>Fragments are named either <samp><span class="file">t-</span><var>target</var></samp> or <samp><span class="file">x-</span><var>host</var></samp>,
depending on whether they are relevant to configuring GCC to produce
code for a particular target, or to configuring GCC to run on a
particular host. Here <var>target</var> and <var>host</var> are mnemonics
which usually have some relationship to the canonical system name, but
no formal connection.
<p>If these files do not exist, it means nothing needs to be added for a
given target or host. Most targets need a few <samp><span class="file">t-</span><var>target</var></samp>
fragments, but needing <samp><span class="file">x-</span><var>host</var></samp> fragments is rare.
<ul class="menu">
<li><a accesskey="1" href="Target-Fragment.html#Target-Fragment">Target Fragment</a>: Writing <samp><span class="file">t-</span><var>target</var></samp> files.
<li><a accesskey="2" href="Host-Fragment.html#Host-Fragment">Host Fragment</a>: Writing <samp><span class="file">x-</span><var>host</var></samp> files.
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