source: chapter06/linux-headers.xml@ eae8d88

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<sect1 id="ch-system-linux-headers" role="wrap">
  <?dbhtml filename="linux-headers.html"?>

  <sect1info condition="script">
    <productname>linux</productname>
    <productnumber>&linux-version;</productnumber>
    <address>&linux-url;</address>
  </sect1info>

  <title>Linux-&linux-version; API Headers</title>

  <indexterm zone="ch-system-linux-headers">
    <primary sortas="a-Linux">Linux</primary>
    <secondary>API headers</secondary>
  </indexterm>

  <sect2 role="package">
    <title/>

    <para>The Linux API Headers expose the kernel's API for use by Glibc.</para>

    <segmentedlist>
      <segtitle>&buildtime;</segtitle>
      <segtitle>&diskspace;</segtitle>

      <seglistitem>
        <seg>&linux-headers-ch6-sbu;</seg>
        <seg>&linux-headers-ch6-du;</seg>
      </seglistitem>
    </segmentedlist>

  </sect2>

  <sect2 role="installation">
    <title>Installation of Linux API Headers</title>

    <para>The Linux kernel needs to expose an Application Programming Interface
    (API) for the system's C library (Glibc in LFS) to use.  This is done
    by way of sanitizing various C header files that are shipped in the Linux
    kernel source tarball.</para>

    <para>Apply a patch to the Linux headers, to fix a bug that can cause
    compilation issues for some userspace applications:</para>

<screen><userinput remap="pre">patch -Np1 -i ../&linux-header-patch;</userinput></screen>

    <para>Make sure there are no stale files and dependencies lying around
    from previous activity:</para>

<screen><userinput remap="install">make mrproper</userinput></screen>

    <para>Now test and extract the user-visible kernel headers from the source.
    They are placed in an intermediate local directory and copied to the needed
    location because the extraction process removes any existing files in 
    the target directory.</para>

<screen><userinput remap="install">make headers_check
make INSTALL_HDR_PATH=dest headers_install
cp -rv dest/include/* /usr/include</userinput></screen>

  </sect2>

  <sect2 id="contents-linux-headers" role="content">
    <title>Contents of Linux API Headers</title>

    <segmentedlist>
      <segtitle>Installed headers</segtitle>

      <seglistitem>
        <seg>/usr/include/{asm{,-generic},drm,linux,mtd,rdma,sound,video}/*.h</seg>
      </seglistitem>
    </segmentedlist>

    <variablelist>
      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
      <?dbfo list-presentation="list"?>
      <?dbhtml list-presentation="table"?>

      <varlistentry id="linux-headers">
        <term><filename class="headerfile">/usr/include/{asm{,-generic},drm,linux,mtd,rdma,sound,video}/*.h</filename></term>
        <listitem>
          <para>The Linux API headers</para>
          <indexterm zone="ch-system-linux-headers">
            <!-- No /*.h here to prevent a PDF line overflow -->
            <primary sortas="e-/usr/include/{asm{,-generic},drm,linux,mtd,rdma,sound,video}">/usr/include/{asm{,-generic},drm,linux,mtd,
rdma,sound,video}/*.h</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>