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Next: <a href="Fragments.html#Fragments" accesskey="n" rel="next">Fragments</a>, Previous: <a href="Target-Macros.html#Target-Macros" accesskey="p" rel="prev">Target Macros</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Host-Configuration"></a>
<h2 class="chapter">19 Host Configuration</h2>
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<p>Most details about the machine and system on which the compiler is
actually running are detected by the <code>configure</code> script. Some
things are impossible for <code>configure</code> to detect; these are
described in two ways, either by macros defined in a file named
<samp>xm-<var>machine</var>.h</samp> or by hook functions in the file specified
by the <var>out_host_hook_obj</var> variable in <samp>config.gcc</samp>. (The
intention is that very few hosts will need a header file but nearly
every fully supported host will need to override some hooks.)
</p>
<p>If you need to define only a few macros, and they have simple
definitions, consider using the <code>xm_defines</code> variable in your
<samp>config.gcc</samp> entry instead of creating a host configuration
header. See <a href="System-Config.html#System-Config">System Config</a>.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="Host-Common.html#Host-Common" accesskey="1">Host Common</a>:</td><td> </td><td align="left" valign="top">Things every host probably needs implemented.
</td></tr>
<tr><td align="left" valign="top">• <a href="Filesystem.html#Filesystem" accesskey="2">Filesystem</a>:</td><td> </td><td align="left" valign="top">Your host cannot have the letter ‘a’ in filenames?
</td></tr>
<tr><td align="left" valign="top">• <a href="Host-Misc.html#Host-Misc" accesskey="3">Host Misc</a>:</td><td> </td><td align="left" valign="top">Rare configuration options for hosts.
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