path: root/chapter06/udev.xml

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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
]>

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

  <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>0.1 SBU</seg>
        <seg>3.1 MB</seg>
      </seglistitem>
    </segmentedlist>

    <segmentedlist>
      <segtitle>&dependencies;</segtitle>

      <seglistitem>
        <seg>Coreutils and Make</seg>
      </seglistitem>
    </segmentedlist>

  </sect2>

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

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

<screen><userinput>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
install -dv /lib/{firmware,udev/devices/{pts,shm}}</userinput></screen>

    <para>Compile the package:</para>

<screen><userinput>make \
EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id extras/firmware extras/floppy extras/scsi_id extras/usb_id extras/volume_id"</userinput></screen>

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

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

    </variablelist>

    <para>To test the results, issue:
    <userinput>make test</userinput>.</para>

    <para>Install the package:</para>

<screen><userinput>make DESTDIR=/ \
EXTRAS="extras/ata_id extras/cdrom_id extras/edd_id extras/firmware extras/floppy extras/scsi_id extras/usb_id extras/volume_id" \
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's configuration is far from ideal by default, so install
    the configuration files here:</para>

<screen><userinput>cp -v ../&udev-config-file; /etc/udev/rules.d/25-lfs.rules</userinput></screen>

    <para>Alter Udev's configuration file so that Udev can automatically
    load kernel modules.</para>

<screen><userinput>sed -i 147,150d /etc/udev/rules.d/25-lfs.rules
cat &gt;&gt; /etc/udev/rules.d/25-lfs.rules &lt;&lt; "EOF"
# Rules to allow hotplugging of devices with modular drivers
ACTION=="add", SUBSYSTEM=="?*", ENV{MODALIAS}=="?*", \
  RUN+="/sbin/modprobe $env{MODALIAS}"
ACTION=="add", SUBSYSTEM=="scsi", SYSFS{type}=="[07]", \
  RUN+="/sbin/modprobe sd_mod"
EOF</userinput></screen>

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

<screen><userinput>install -m644 -D -v docs/writing_udev_rules/index.html /usr/share/doc/udev-&udev-version;/index.html</userinput></screen>

    <!-- Not for the LiveCD -->
    <!-- Edit Me -->

    <para>Run the <command>udevstart</command> program to create our full
    complement of device nodes.</para>

<screen><userinput>/sbin/udevstart</userinput></screen>

  </sect2>

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

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

      <seglistitem>
        <seg>ata_id, cdrom_id, create_floppy_devices, edd_id, firmware_helper,
        scsi_id, udevcontrol, udevd, udevinfo, udevmonitor, udevtest, usb_id
        and vol_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 <command>udev</command> 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 <command>udev</command> 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="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 <command>udev</command> 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_helper">
        <term><command>firmware_helper</command></term>
        <listitem>
          <para>Enables <command>udev</command> to upload firmware to
          devices</para>
          <indexterm zone="ch-system-udev firmware_helper">
            <primary sortas="b-firmware_helper">firmware_helper</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="scsi_id">
        <term><command>scsi_id</command></term>
        <listitem>
          <para>Provides <command>udev</command> 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="udevcontrol">
        <term><command>udevcontrol</command></term>
        <listitem>
          <para>Configures a number of options for the running
          <command>udevd</command> daemon, such as the log level.</para>
          <indexterm zone="ch-system-udev udevcontrol">
            <primary sortas="b-udevcontrol">udevcontrol</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevd">
        <term><command>udevd</command></term>
        <listitem>
          <para>A daemon that reorders hotplug events before submitting them to
          <command>udev</command>, thus avoiding various race conditions</para>
          <indexterm zone="ch-system-udev udevd">
            <primary sortas="b-udevd">udevd</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevinfo">
        <term><command>udevinfo</command></term>
        <listitem>
          <para>Allows users to query the <command>udev</command> database for
          information on any device currently present on the system; it also
          provides a way to query any device in the <systemitem
          class="filesystem">sysfs</systemitem> tree to help create udev
          rules</para>
          <indexterm zone="ch-system-udev udevinfo">
            <primary sortas="b-udevinfo">udevinfo</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevmonitor">
        <term><command>udevmonitor</command></term>
        <listitem>
          <para>Prints the event received from the kernel and the event which
          <command>udev</command> sends out after rule processing</para>
          <indexterm zone="ch-system-udev udevmonitor">
            <primary sortas="b-udevmonitor">udevmonitor</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="udevtest">
        <term><command>udevtest</command></term>
        <listitem>
          <para>Simulates a <command>udev</command> run for the given device,
          and prints out the name of the node the real <command>udev</command>
          would have created or (not in LFS) the name of the renamed network
          interface</para>
          <indexterm zone="ch-system-udev udevtest">
            <primary sortas="b-udevtest">udevtest</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="usb_id">
        <term><command>usb_id</command></term>
        <listitem>
          <para>Provides <command>udev</command> 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 <command>udev</command> 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="etc-udev">
        <term><filename class="directory">/etc/udev</filename></term>
        <listitem>
          <para>Contains <command>udev</command> configuation 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>