lfs-book/chapter06/linux-headers.xml

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  <!ENTITY % general-entities SYSTEM "../general.ent">
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<sect1 id="ch-system-linux-headers" role="wrap">
  <?dbhtml filename="linux-headers.html"?>

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

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

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

    <para>The Linux-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-Headers</title>

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

    <para>Apply the following patch to provide <command>unifdef</command>, which
    the installation of the kernel headers requires:</para>

<screen><userinput>patch -Np1 -i ../linux-&linux-version;-unifdef-1.patch</userinput></screen>

    <para>Install the header files:</para>

<screen><userinput>make mrproper
make headers_check
make INSTALL_HDR_PATH=/usr headers_install</userinput></screen>

    <para>Ensure that all the headers are owned by root:</para>

<screen><userinput>chown -Rv root:root /usr/include/{asm,linux}</userinput></screen>

    <para>Make sure the users can read the headers:</para>

<screen><userinput>find /usr/include/{asm,linux} -type d -exec chmod -v 755 {} \;
find /usr/include/{asm,linux} -type f -exec chmod -v 644 {} \;</userinput></screen>

  </sect2>

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

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

      <seglistitem>
        <seg>/usr/include/{asm,linux}/*.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,linux}/*.h</filename></term>
        <listitem>
          <para>The Linux API headers</para>
          <indexterm zone="ch-system-linux-headers linux-headers">
            <primary sortas="e-/usr/include/{asm,linux}/*.h">/usr/include/{asm,linux}/*.h</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>