source: chapter06/udev.xml@ 6b85f8a

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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../general.ent">
  %general-entities;
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<sect1 id="ch-system-udev" role="wrap">
<title>Udev-&udev-version;</title>
<?dbhtml filename="udev.html"?>

<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>0.2 SBU</seg><seg>5.2 MB</seg></seglistitem>
</segmentedlist>

<segmentedlist>
<segtitle>Udev installation depends on</segtitle>
<seglistitem><seg>Coreutils, Make</seg></seglistitem>
</segmentedlist>

</sect2>

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

<para>Compile Udev:</para>

<screen><userinput>make udevdir=/dev</userinput></screen>

<variablelist>
<varlistentry>
<term><parameter>udevdir=/dev</parameter></term>
<listitem><para>This tells <command>udev</command> in which directory
devices nodes are to be created.</para></listitem>
</varlistentry>
</variablelist>

<para>Install the package:</para>

<screen><userinput>make udevdir=/dev install</userinput></screen>

<para>Udev's configuration is far from ideal by default, so we install our own
configuration files here:</para>

<screen><userinput>cp ../udev-config-2.permissions /etc/udev/permissions.d/00-lfs.permissions
cp ../udev-config-1.rules /etc/udev/rules.d/00-lfs.rules</userinput></screen>

</sect2>

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

<segmentedlist>
<segtitle>Installed programs</segtitle>
<seglistitem><seg>udev, udevd, udevsend, udevstart, udevinfo, udevtest</seg></seglistitem>
</segmentedlist>

<variablelist><bridgehead renderas="sect3">Short descriptions</bridgehead>
<?dbfo list-presentation="list"?>
                                                                                
<varlistentry id="udev">
<term><command>udev</command></term>
<listitem>
<para>is used to create device nodes in <filename
class="directory">/dev</filename> or to rename network interfaces (not
in LFS) in response to hotplug events.</para>
<indexterm zone="ch-system-udev udev"><primary sortas="b-udev">udev</primary></indexterm>
</listitem></varlistentry>

<varlistentry id="udevd">
<term><command>udevd</command></term>
<listitem>
<para>is 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="udevsend">
<term><command>udevsend</command></term>
<listitem>
<para>is used to deliver hotplug events to <command>udevd</command>.</para>
<indexterm zone="ch-system-udev udevsend"><primary sortas="b-udevsend">udevsend</primary></indexterm>
</listitem></varlistentry>

<varlistentry id="udevstart">
<term><command>udevstart</command></term>
<listitem>
<para>is used to create device nodes in <filename
class="directory">/dev</filename> that correspond to drivers compiled directly
into the kernel. It performs that task by simulating hotplug events presumably
dropped by the kernel before invocation of this program (e.g. because the root
filesystem has not been mounted) and submitting such synthetic hotplug events
to <command>udev</command>.</para>
<indexterm zone="ch-system-udev udevstart"><primary sortas="b-udevstart">udevstart</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 creating udev
rules.</para>
<indexterm zone="ch-system-udev udevinfo"><primary sortas="b-udevinfo">udevinfo</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="etc-dev-d">
<term><filename class="directory">/etc/dev.d</filename></term>
<listitem>
<para>directory contains user-written handlers for device
creation hotplug events.</para>
<indexterm zone="ch-system-udev etc-dev-d"><primary sortas="e-etc-dev-d">/etc/dev.d</primary></indexterm>
</listitem></varlistentry>

<varlistentry id="etc-udev">
<term><filename class="directory">/etc/udev</filename></term>
<listitem>
<para>directory 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>