lfs-book/chapter06/udev.xml

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  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
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<sect1 id="ch-system-udev" role="wrap">
  <?dbhtml filename="udev.html"?>

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

  <title>Udev-&udev-version;</title>

  <indexterm zone="ch-system-udev">
    <primary sortas="a-Udev">Udev</primary>
  </indexterm>

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

    <para>The Udev package contains programs for dynamic creation of device
    nodes.</para>

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

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

  </sect2>

  <sect2 role="installation">
    <title>Installation of Udev</title>

    <para>The udev-config tarball contains LFS-specific files used to configure
    Udev. Unpack it into the Udev source directory:</para>

<screen><userinput remap="pre">tar -xvf ../&udev-config;.tar.bz2</userinput></screen>

    <para>Create some devices and directories that Udev cannot handle due to
    them being required very early in the boot process, or by Udev itself:</para>

<screen><userinput remap="install">install -dv /lib/{firmware,udev/devices/{pts,shm}}
mknod -m0666 /lib/udev/devices/null c 1 3
mknod -m0600 /lib/udev/devices/kmsg c 1 11
ln -sv /proc/self/fd /lib/udev/devices/fd
ln -sv /proc/self/fd/0 /lib/udev/devices/stdin
ln -sv /proc/self/fd/1 /lib/udev/devices/stdout
ln -sv /proc/self/fd/2 /lib/udev/devices/stderr
ln -sv /proc/kcore /lib/udev/devices/core</userinput></screen>

    <para>Compile the package:</para>

<screen><userinput remap="make">make EXTRAS="`echo extras/*/`"</userinput></screen>

    <variablelist>
      <title>The meaning of the make option:</title>

      <varlistentry>
        <term><parameter>EXTRAS=...</parameter></term>
        <listitem>
          <para>This builds the helper binaries that can aid in writing custom
          Udev rules.</para>
        </listitem>
      </varlistentry>

    </variablelist>

    <para>To test the results, issue:</para>

<screen><userinput remap="test">make test</userinput></screen>

    <para>Note that the Udev testsuite will produce numerous messages in
    the host system's logs. These are harmless and can be ignored.</para>

    <para>Install the package:</para>

<screen><userinput remap="install">make DESTDIR=/ EXTRAS="`echo extras/*/`" install</userinput></screen>

    <variablelist>
      <title>The meaning of the make parameter:</title>

      <varlistentry>
        <term><parameter>DESTDIR=/</parameter></term>
        <listitem>
          <para>This prevents the Udev build process from killing any
          <command>udevd</command> processes that may be running on the
          host system.</para>
        </listitem>
      </varlistentry>

    </variablelist>

    <para>Udev has to be configured in order to work properly, as its default
    configuration does not cover all devices. First install a few extra rules
    files from Udev to help support device-mapper and RAID setups:</para>

<screen><userinput remap="install">install -m644 -v etc/udev/packages/64-*.rules \
    /etc/udev/rules.d/</userinput></screen>

    <para>Now install a file to create symlinks for certain hand-held devices:</para>

<screen><userinput remap="install">install -m644 -v etc/udev/packages/40-pilot-links.rules \
    /etc/udev/rules.d/40-pilot-links.rules</userinput></screen>

    <!-- There are more files available in the packages/ directory, if we want
         to consider using them.  Most are probably irrelevant to LFS though.
         "alsa" isn't, but we already have those rules, using a better set of
         matches.  Most of the files in packages/ are for other architectures. -->

    <para>Now install the LFS-specific custom rules files:</para>

<screen><userinput remap="install">cd &udev-config;
make install</userinput></screen>

    <para>Install the documentation that explains the LFS-specific rules
    files:</para>

<screen><userinput remap="install">make install-doc</userinput></screen>

    <para>Install the documentation that explains the commonly-used rules
    files provided by Udev:</para>

<screen><userinput remap="install">make install-extra-doc</userinput></screen>

    <para>Install the documentation that explains how to create custom Udev
    rules:</para>

<screen><userinput remap="install">cd ..
install -dv /usr/share/doc/udev-&udev-version;
install -m644 -v docs/writing_udev_rules/index.html \
    /usr/share/doc/udev-&udev-version;/index.html</userinput></screen>

  </sect2>

  <sect2 id="contents-udev" role="content">
    <title>Contents of Udev</title>

    <segmentedlist>
      <segtitle>Installed programs</segtitle>
      <segtitle>Installed libraries</segtitle>
      <segtitle>Installed directory</segtitle>

      <seglistitem>
        <seg>ata_id, cdrom_id, collect, create_floppy_devices, edd_id,
        firmware.sh, fstab_import, path_id, scsi_id, udevadm, udevd,
        usb_id, vol_id, write_cd_rules, and write_net_rules</seg>
        <seg>libvolume_id</seg>
        <seg>/etc/udev</seg>
      </seglistitem>
    </segmentedlist>

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

      <varlistentry id="ata_id">
        <term><command>ata_id</command></term>
        <listitem>
          <para>Provides Udev with a unique string and
          additional information (uuid, label) for an ATA drive</para>
          <indexterm zone="ch-system-udev ata_id">
            <primary sortas="b-ata_id">ata_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="cdrom_id">
        <term><command>cdrom_id</command></term>
        <listitem>
          <para>Provides Udev with the capabilities of a
          CD-ROM or DVD-ROM drive</para>
          <indexterm zone="ch-system-udev cdrom_id">
            <primary sortas="b-cdrom_id">cdrom_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="collect">
        <term><command>collect</command></term>
        <listitem>
          <para>Given an ID for the current uevent and a list of
          IDs (for all target uevents), registers the current ID
          and indicates whether all target IDs have been registered</para>
          <indexterm zone="ch-system-udev collect">
            <primary sortas="b-collect">collect</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="create_floppy_devices">
        <term><command>create_floppy_devices</command></term>
        <listitem>
          <para>Creates all possible floppy devices based on the CMOS type</para>
          <indexterm zone="ch-system-udev create_floppy_devices">
            <primary sortas="b-create_floppy_devices">create_floppy_devices</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="edd_id">
        <term><command>edd_id</command></term>
        <listitem>
          <para>Provides Udev with the EDD ID for a BIOS disk drive</para>
          <indexterm zone="ch-system-udev edd_id">
            <primary sortas="b-edd_id">edd_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="firmware.sh">
        <term><command>firmware.sh</command></term>
        <listitem>
          <para>Uploads firmware to devices</para>
          <indexterm zone="ch-system-udev firmware.sh">
            <primary sortas="b-firmware.sh">firmware.sh</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="fstab_import">
        <term><command>fstab_import</command></term>
        <listitem>
          <para>Finds an entry in <filename>/etc/fstab</filename> that
          matches the current device, and provides its information to
          Udev</para>
          <indexterm zone="ch-system-udev fstab_import">
            <primary sortas="b-fstab_import">fstab_import</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="path_id">
        <term><command>path_id</command></term>
        <listitem>
          <para>Provides the shortest possible unique hardware path to a
          device</para>
          <indexterm zone="ch-system-udev path_id">
            <primary sortas="b-path_id">path_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="scsi_id">
        <term><command>scsi_id</command></term>
        <listitem>
          <para>Provides Udev with a unique SCSI identifier
          based on the data returned from sending a SCSI INQUIRY command to
          the specified device</para>
          <indexterm zone="ch-system-udev scsi_id">
            <primary sortas="b-scsi_id">scsi_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevadm">
        <term><command>udevadm</command></term>
        <listitem>
          <para>Generic udev administration tool: controls the udevd daemon,
          provides info from the Udev database, monitors uevents, waits for
          uevents to finish, tests Udev configuration, and triggers uevents
          for a given device</para>
          <indexterm zone="ch-system-udev udevadm">
            <primary sortas="b-udevadm">udevadm</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevd">
        <term><command>udevd</command></term>
        <listitem>
          <para>A daemon that listens for uevents on the netlink socket,
          creates devices and runs the configured external programs in
          response to these uevents</para>
          <indexterm zone="ch-system-udev udevd">
            <primary sortas="b-udevd">udevd</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="usb_id">
        <term><command>usb_id</command></term>
        <listitem>
          <para>Provides Udev with information about USB
          devices</para>
          <indexterm zone="ch-system-udev usb_id">
            <primary sortas="b-usb_id">usb_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="vol_id">
        <term><command>vol_id</command></term>
        <listitem>
          <para>Provides Udev with the label and uuid of a
          filesystem</para>
          <indexterm zone="ch-system-udev vol_id">
            <primary sortas="b-vol_id">vol_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="write_cd_rules">
        <term><command>write_cd_rules</command></term>
        <listitem>
          <para>A script which generates Udev rules to provide stable names for
          optical drives (see also <xref linkend="ch-scripts-symlinks"/>)</para>
          <indexterm zone="ch-system-udev write_cd_rules">
            <primary sortas="b-write_cd_rules">write_cd_rules</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="write_net_rules">
        <term><command>write_net_rules</command></term>
        <listitem>
          <para>A script which generates rules to provide stable names for
          network interfaces (see also <xref linkend="ch-scripts-network"/>)
          </para>
          <indexterm zone="ch-system-udev write_net_rules">
            <primary sortas="b-write_net_rules">write_net_rules</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libvolume_id">
        <term><command>libvolume_id</command></term>
        <listitem>
          <para></para>
          <indexterm zone="ch-system-udev libvolume_id">
            <primary sortas="c-libvolume_id">libvolume_id</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="etc-udev">
        <term><filename class="directory">/etc/udev</filename></term>
        <listitem>
          <para>Contains Udev configuration files,
          device permissions, and rules for device naming</para>
          <indexterm zone="ch-system-udev etc-udev">
            <primary sortas="e-/etc/udev">/etc/udev</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>