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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 -d /usr/{lib,share}/pkgconfig
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>
<para>Install the man pages:</para>
<!-- Please make sure systemd man pages tarball has a common leading
component in the path. -->
<screen><userinput remap="install">tar -xf ../../systemd-man-pages-253.tar.xz --strip-components=1 \
-C /usr/share/man --wildcards '*/udev*' '*/libudev*' \
'*/systemd-'{hwdb,udevd.service}.8
sed 's/systemd\(\\\?-\)/udev-/' /usr/share/man/man8/systemd-hwdb.8 \
> /usr/share/man/man8/udev-hwdb.8
sed 's|lib.*udevd|sbin/udevd|' \
/usr/share/man/man8/systemd-udevd.service.8 \
> /usr/share/man/man8/udevd.8
rm /usr/share/man/man8/systemd-*.8</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>
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