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+<?xml version="1.0" encoding="ISO-8859-1"?>
+<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+ <!ENTITY % general-entities SYSTEM "../general.ent">
+ %general-entities;
+]>
+
+<sect1 id="ch-system-udev" role="wrap" revision="sysv">
+ <?dbhtml filename="udev.html"?>
+
+ <sect1info condition="script">
+ <productname>udev</productname>
+ <productnumber>&systemd-version;</productnumber>
+ <address>&systemd-url;</address>
+ </sect1info>
+
+ <title>Udev from Systemd-&systemd-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-fin-sbu;</seg>
+ <seg>&udev-fin-du;</seg>
+ </seglistitem>
+ </segmentedlist>
+ </sect2>
+
+ <sect2 role="installation">
+ <title>Installation of Udev</title>
+
+ <para>Udev is part of the systemd-&systemd-version; package. Use
+ the systemd-&systemd-version;.tar.xz file as the source tarball.</para>
+
+ <para>Remove two unneeded groups,
+ <systemitem class="groupname">render</systemitem> and
+ <systemitem class="groupname">sgx</systemitem>, from the default udev
+ rules:</para>
+
+ <screen><userinput remap="pre">sed -i -e 's/GROUP="render"/GROUP="video"/' \
+ -e 's/GROUP="sgx", //' rules.d/50-udev-default.rules.in</userinput></screen>
+
+ <para>Prepare Udev for compilation:</para>
+
+<screen><userinput remap="configure">mkdir -p build
+cd build
+
+meson setup \
+ --prefix=/usr \
+ --buildtype=release \
+ -Dmode=release \
+ -Ddev-kvm-mode=0660 \
+ -Dlink-udev-shared=false \
+ ..</userinput></screen>
+
+ <variablelist>
+ <title>The meaning of the meson options:</title>
+
+ <varlistentry>
+ <term><parameter>--buildtype=release</parameter></term>
+ <listitem>
+ <para>This switch overrides the default buildtype
+ (<quote>debug</quote>), which produces unoptimized
+ binaries.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><parameter>-Dmode=release</parameter></term>
+ <listitem>
+ <para>Disable some features considered experimental by upstream.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><parameter>-Ddev-kvm-mode=0660</parameter></term>
+ <listitem>
+ <para>The default udev rule would allow all users to access
+ <filename class='devicefile'>/dev/kvm</filename>. The editors
+ consider it dangerous. This option overrides it.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><parameter>-Dlink-udev-shared=false</parameter></term>
+ <listitem>
+ <para>This option prevents udev from linking to the internal
+ systemd shared library,
+ <systemitem class='library'>libsystemd-shared</systemitem>.
+ This library is designed to be shared by many Systemd components
+ and it's too overkill for a udev-only installation.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Only build the components needed for udev:</para>
+
+ <screen><userinput remap="make">ninja udevadm systemd-hwdb \
+ $(grep -o -E "^build (src/libudev|src/udev|rules.d|hwdb.d)[^:]*" \
+ build.ninja | awk '{ print $2 }') \
+ $(realpath libudev.so --relative-to .)</userinput></screen>
+
+ <para>Install the package:</para>
+
+ <screen><userinput remap="install">install -vm755 -d {/usr/lib,/etc}/udev/{hwdb,rules}.d
+install -vm755 udevadm /usr/bin/
+install -vm755 systemd-hwdb /usr/bin/udev-hwdb
+ln -sv ../bin/udevadm /usr/sbin/udevd
+cp -av libudev.so{,*[0-9]} /usr/lib/
+install -vm644 ../src/libudev/libudev.h /usr/include/
+install -vm644 src/libudev/*.pc /usr/lib/pkgconfig/
+install -vm644 src/udev/*.pc /usr/share/pkgconfig/
+install -vm644 ../src/udev/udev.conf /etc/udev/
+install -vm644 rules.d/* ../rules.d/{*.rules,README} /usr/lib/udev/rules.d/
+install -vm644 hwdb.d/* ../hwdb.d/{*.hwdb,README} /usr/lib/udev/hwdb.d/
+install -vm755 $(find src/udev -type f | grep -F -v ".") /usr/lib/udev</userinput></screen>
+
+ <para>Install some custom rules and support files useful in an LFS
+ environment:</para>
+
+<screen><userinput remap="install">tar -xvf ../../&udev-lfs-version;.tar.xz
+make -f &udev-lfs-version;/Makefile.lfs install</userinput></screen>
+
+ </sect2>
+
+ <sect2 id="conf-udev" role="configuration">
+ <title>Configuring Udev</title>
+
+ <indexterm zone="conf-udev">
+ <primary sortas="a-Udev">Udev</primary>
+ <secondary>configuring</secondary>
+ </indexterm>
+
+ <indexterm zone="conf-udev">
+ <primary sortas="e-/etc/udev/hwdb.bin">/etc/udev/hwdb.bin</primary>
+ </indexterm>
+
+ <para>Information about hardware devices is maintained in the
+ <filename class="directory">/etc/udev/hwdb.d</filename> and
+ <filename class="directory">/usr/lib/udev/hwdb.d</filename> directories.
+ <application>Udev</application> needs that information to be compiled
+ into a binary database <filename>/etc/udev/hwdb.bin</filename>. Create the
+ initial database:</para>
+
+<screen><userinput>udev-hwdb update</userinput></screen>
+
+ <para>This command needs to be run each time the hardware information is
+ updated.</para>
+
+ </sect2>
+
+ <sect2 id="contents-udev" role="content">
+ <title>Contents of Udev</title>
+
+ <segmentedlist>
+ <segtitle>Installed programs</segtitle>
+ <segtitle>Installed libraries</segtitle>
+ <segtitle>Installed directories</segtitle>
+
+ <seglistitem>
+ <seg>udevadm, udevd (symlink to udevadm), and udev-hwdb</seg>
+
+ <seg>libudev.so</seg>
+
+ <seg>/etc/udev and /usr/lib/udev</seg>
+ </seglistitem>
+ </segmentedlist>
+
+ <variablelist>
+ <bridgehead renderas="sect3">Short Descriptions</bridgehead>
+ <?dbfo list-presentation="list"?>
+ <?dbhtml list-presentation="table"?>
+ <varlistentry id="udevadm" revision="sysv">
+ <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="udev-hwdb">
+ <term><command>udev-hwdb</command></term>
+ <listitem>
+ <para>Updates or query the hardware database.</para>
+ <indexterm zone="ch-system-udev udev-hwdb">
+ <primary sortas="b-udev-hwdb">udev-hwdb</primary>
+ </indexterm>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id="libudev">
+ <term><filename class="libraryfile">libudev</filename></term>
+ <listitem>
+ <para>A library interface to udev device information</para>
+ <indexterm zone="ch-system-udev libudev">
+ <primary sortas="c-libudev">libudev</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>