building goes on for a given recipe.
</para>
</section>
+
+ <section id='patching-dev-environment'>
+ <title>Patching</title>
+
+ <para>
+ Once source code is fetched and unpacked, BitBake locates
+ patch files and applies them to the source files:
+ <imagedata fileref="figures/patching.png" align="center" width="6in" depth="5in" />
+ </para>
+
+ <para>
+ The <filename>do_patch</filename> task processes recipes by
+ using the
+ <link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
+ variable to locate applicable patch files, which by default
+ are <filename>*.patch</filename> or
+ <filename>*.diff</filename> files, or any file if
+ "apply=yes" is specified for the file in
+ <filename>SRC_URI</filename>.
+ </para>
+
+ <para>
+ BitBake finds and applies multiple patches for a single recipe
+ in the order in which it finds the patches.
+ Patches are applied to the recipe's source files located in the
+ <link linkend='var-S'><filename>S</filename></link> directory.
+ </para>
+
+ <para>
+ For more information on how the source directories are
+ created, see the
+ "<link linkend='source-fetching-dev-environment'>Source Fetching</link>"
+ section.
+ </para>
+ </section>
</section>
</section>