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<?xml version="1.0" encoding="UTF-8"?>
<section id="siteinfo_class" xreflabel="siteinfo class">
<title>siteinfo class</title>
<para>The siteinfo class provides information for a target with a particular
emphasis on determining the names of the site files to be passed to
autoconf, as described in the <xref linkend="autotools_class" />. Full site
information for your target can be determined by looking at the table in the
class implementation found in the
<command>classes/siteinfo.bbclass</command> file. A typical entry contains
the name of the target and a list of site information for the
target:<screen> "sh4-linux": "endian-little bit-32 common-glibc sh-common",</screen>In
the above example for sh4-linux target (that's a build for an sh4 processor
using glibc) we see that the endianess and bit-size of target are defined
and an additional set of site files that should be used are listed. These
include a common site file for glibc and a common site file for sh
processors (so sh3 and sh4 can share defines). A <command>"common"</command>
entry is automatically added to the end of each of the definitions during
processing.</para>
<para>The class makes available three variables based on the information
provided for a target:</para>
<variablelist>
<varlistentry>
<term>SITEINFO_ENDIANNESS</term>
<listitem>
<para>Defines the endianess of the target as either
<command>"le"</command> (little endian) or <command>"be"</command>
(big endian). The target must list either
<command>endian-little</command> or <command>endian-big</command> in
it's site information.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SITEINFO_BITS</term>
<listitem>
<para>Defines the bitsize of the target as either
<command>"32"</command> or <command>"64"</command>. The target must
list either <command>bit-32</command> or <command>bit-64</command> in
it's site information.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CONFIG_SITE</term>
<listitem>
<para>Defines the site files to be used by autoconf. This is a space
separated list of one or more site files for the target.</para>
</listitem>
</varlistentry>
</variablelist>
<para>A typical use for the <command>SITEINFO_ENDIANNESS</command> and
<command>SITEINFO_BITS</command> variables is to provide configuration
within a recipe based on their values. The following example from the
<emphasis>openssl</emphasis> recipe showw the correct define for the
endiness of the target being passed to openssl via the compiler flags. The
define to add to the flags is set based on the value of the
<command>SITEINFO_ENDIANNESS</command> variable. Note that use of the
<emphasis>base_conditional</emphasis> method (see the <xref
linkend="recipes_advanced_python" /> section) to select a value conditional
on the endianess setting:</para>
<para><screen> # Additional flag based on target endiness (see siteinfo.bbclass)
CFLAG="${CFLAG} ${@base_conditional('SITEINFO_ENDIANNESS', 'le', '-DL_ENDIAN', '-DB_ENDIAN', d)}"</screen></para>
<section>
<title>CONFIG_SITE: The autoconf site files</title>
<para>The autotools configuration method has support for caching the
results of tests. In the cross-compilation case it is sometimes necessary
to prime the cache with per-calculated results (since tests designed to
run on the target cannot be run when cross-compiling). These are defined
via the site file(s) for the architecture you are using and may be
specific to the package you are building.</para>
<para>Which site files are used is determined via the
<command>CONFIG_SITE</command> definition which is calculated via the
siteinfo class. Typically the following site files will be checked for,
and used in the order found:</para>
<variablelist>
<varlistentry>
<term>endian-(big|little)</term>
<listitem>
<para>Either <command>endian-big</command> or
<command>endian-little</command> depending on the endianess of the
target. This site file would contain defines that only change based
on if the target is little endian or big endian.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>bit-(32|64)</term>
<listitem>
<para>Either <command>bit-32</command> or <command>bit-64</command>
depending on the bitsize of the target. This site file would contain
defines that only change based on if the target is a 32-bit or
64-bit cpu.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>common-(libc|uclibc)</term>
<listitem>
<para>Either <command>common-libc</command> or
<command>common-uclibc</command> based on the C library being used
for the target. This site file would contain defines the are
specific to the C library being used.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><arch>-common</term>
<listitem>
<para>A common site file for the target architecture. For i386,
i485, i586 and i686 this would be <command>x86-common</command>, for
sh3 and sh4 this would be <command>sh-common</command> and for
various arm targets this would be
<command>arm-common</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>common</term>
<listitem>
<para>This is a site file which is common for all targets and
contains definitions which remain the same no matter what target is
being built.</para>
</listitem>
</varlistentry>
</variablelist>
<para>Each of the supported site files for a target is will be checked for
in several different directories. Each time a file is found it as added to
the list of files in the <command>CONFIG_SITE</command> variable. The
following directories are checked:</para>
<variablelist>
<varlistentry>
<term>org.openembedded.dev/recipes/<packagename>/site-<version>/</term>
<listitem>
<para>This directory is for site files which are specific to a
particular version (where version is the PV of the package) of a
package.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>org.openembedded.dev/recipes/<packagename>/site/</term>
<listitem>
<para>This directory is for site files which are specific to a
particular package, but apply to all versions of the package.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>org.openembedded.dev/site/</term>
<listitem>
<para>This directory is for site files that are common to all
packages. Originally this was the only site file directory that was
supported.</para>
</listitem>
</varlistentry>
</variablelist>
</section>
</section>
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