mirror of
https://github.com/systemd/systemd.git
synced 2024-12-23 21:35:11 +03:00
78266a54f1
Most of our kernel cmdline options use underscores as word separators in kernel cmdline options, but there were some exceptions. Let's fix those, and also use underscores. Since our /proc/cmdline parsers don't distinguish between the two characters anyway this should not break anything, but makes sure our own codebase (and in particular docs and log messages) are internally consistent.
312 lines
13 KiB
XML
312 lines
13 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="systemd-udevd.service"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-udevd.service</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-udevd.service</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-udevd.service</refname>
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<refname>systemd-udevd-control.socket</refname>
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<refname>systemd-udevd-kernel.socket</refname>
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<refname>systemd-udevd</refname>
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<refpurpose>Device event managing daemon</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd-udevd.service</filename></para>
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<para><filename>systemd-udevd-control.socket</filename></para>
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<para><filename>systemd-udevd-kernel.socket</filename></para>
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<cmdsynopsis>
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<command>/usr/lib/systemd/systemd-udevd</command>
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<arg><option>--daemon</option></arg>
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<arg><option>--debug</option></arg>
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<arg><option>--children-max=</option></arg>
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<arg><option>--exec-delay=</option></arg>
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<arg><option>--event-timeout=</option></arg>
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<arg><option>--resolve-names=early|late|never</option></arg>
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<arg><option>--version</option></arg>
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<arg><option>--help</option></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1><title>Description</title>
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<para><command>systemd-udevd</command> listens to kernel uevents.
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For every event, systemd-udevd executes matching instructions
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specified in udev rules. See <citerefentry>
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<refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
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</citerefentry>.</para>
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<para>The behavior of the daemon can be configured using
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<citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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its command line options, environment variables, and on the kernel
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command line, or changed dynamically with <command>udevadm
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control</command>.
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</para>
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</refsect1>
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<refsect1><title>Options</title>
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<variablelist>
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<varlistentry>
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<term><option>-d</option></term>
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<term><option>--daemon</option></term>
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<listitem>
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<para>Detach and run in the background.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-D</option></term>
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<term><option>--debug</option></term>
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<listitem>
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<para>Print debug messages to standard error.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-c</option></term>
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<term><option>--children-max=</option></term>
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<listitem>
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<para>Limit the number of events executed in parallel.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-e</option></term>
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<term><option>--exec-delay=</option></term>
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<listitem>
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<para>Delay the execution of each <varname>RUN{<replaceable>program</replaceable>}</varname>
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parameter by the given number of seconds. This option
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might be useful when debugging system crashes during
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coldplug caused by loading non-working kernel
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modules.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-t</option></term>
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<term><option>--event-timeout=</option></term>
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<listitem>
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<para>Set the number of seconds to wait for events to finish. After
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this time, the event will be terminated. The default is 180 seconds.</para>
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<xi:include href="version-info.xml" xpointer="v216"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-s</option></term>
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<term><option>--timeout-signal=</option></term>
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<listitem>
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<para>Set the signal which <filename>systemd-udevd</filename> will send to
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forked off processes after reaching event timeout. The setting can be overridden
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at boot time with the kernel command line option
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<varname>udev.timeout_signal=</varname>. Setting to <constant>SIGABRT</constant>
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may be helpful in order to debug worker timeouts. Defaults to
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<constant>SIGKILL</constant>. Note that setting the option on the command line
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overrides the setting from the configuration file.
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</para>
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<xi:include href="version-info.xml" xpointer="v246"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-N</option></term>
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<term><option>--resolve-names=</option></term>
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<listitem>
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<para>Specify when systemd-udevd should resolve names of users and groups.
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When set to <option>early</option> (the default), names will be
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resolved when the rules are parsed. When set to
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<option>late</option>, names will be resolved for every event.
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When set to <option>never</option>, names will never be resolved
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and all devices will be owned by root.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<xi:include href="standard-options.xml" xpointer="help" />
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<xi:include href="standard-options.xml" xpointer="version" />
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</variablelist>
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</refsect1>
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<refsect1><title>Kernel command line</title>
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<variablelist class='kernel-commandline-options'>
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<para>Parameters prefixed with "rd." will be read when <command>systemd-udevd</command> is used in an
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initrd, those without will be processed both in the initrd and on the host.</para>
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<varlistentry>
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<term><varname>udev.log_level=</varname></term>
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<term><varname>rd.udev.log_level=</varname></term>
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<listitem>
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<para>Set the log level.</para>
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<xi:include href="version-info.xml" xpointer="v247"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>udev.children_max=</varname></term>
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<term><varname>rd.udev.children_max=</varname></term>
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<listitem>
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<para>Limit the number of events executed in parallel.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>udev.exec_delay=</varname></term>
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<term><varname>rd.udev.exec_delay=</varname></term>
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<listitem>
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<para>Delay the execution of each <varname>RUN{<replaceable>program</replaceable>}</varname> parameter by the given
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number of seconds. This option might be useful when
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debugging system crashes during coldplug caused by loading
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non-working kernel modules.</para>
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<xi:include href="version-info.xml" xpointer="v186"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>udev.event_timeout=</varname></term>
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<term><varname>rd.udev.event_timeout=</varname></term>
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<listitem>
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<para>Wait for events to finish up to the given number
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of seconds. This option might be useful if events are
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terminated due to kernel drivers taking too long to initialize.</para>
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<xi:include href="version-info.xml" xpointer="v216"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>udev.timeout_signal=</varname></term>
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<term><varname>rd.udev.timeout_signal=</varname></term>
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<listitem>
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<para>Specifies a signal that <filename>systemd-udevd</filename> will send to
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workers on timeout. Note that kernel command line option overrides both the
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setting in the configuration file and the one on the program command line.</para>
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<xi:include href="version-info.xml" xpointer="v246"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>udev.blockdev_read_only</varname></term>
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<term><varname>rd.udev.blockdev_read_only</varname></term>
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<listitem>
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<para>If specified, mark all physical block devices read-only as they appear. Synthetic block
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devices (such as loopback block devices or device mapper devices) are left as they are. This is
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useful to guarantee that the contents of physical block devices remains unmodified during runtime,
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for example to implement fully stateless systems, for testing or for recovery situations where
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corrupted file systems shall not be corrupted further through accidental modification.</para>
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<para>A block device may be marked writable again by issuing the <command>blockdev
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--setrw</command> command, see <citerefentry
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project='man-pages'><refentrytitle>blockdev</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for details.</para>
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<xi:include href="version-info.xml" xpointer="v246"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>net.ifnames=</varname></term>
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<listitem>
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<para>Network interfaces are renamed to give them predictable names
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when possible. It is enabled by default; specifying 0 disables it.</para>
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<xi:include href="version-info.xml" xpointer="v199"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>net.naming_scheme=</varname></term>
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<listitem>
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<para>Network interfaces are renamed to give them predictable names when possible (unless
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<varname>net.ifnames=0</varname> is specified, see above). With this kernel command line option it
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is possible to pick a specific version of this algorithm and override the default chosen at
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compilation time. Expects one of the naming scheme identifiers listed in
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<citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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or <literal>latest</literal> to select the latest scheme known (to this particular version of
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<filename>systemd-udevd.service</filename>).</para>
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<para>Note that selecting a specific scheme is not sufficient to fully stabilize interface naming:
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the naming is generally derived from driver attributes exposed by the kernel. As the kernel is
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updated, previously missing attributes <filename>systemd-udevd.service</filename> is checking might
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appear, which affects older name derivation algorithms, too.</para>
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<xi:include href="version-info.xml" xpointer="v240"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>net.ifname_policy=<replaceable>policy1</replaceable>[,<replaceable>policy2</replaceable>,…][,<replaceable>MAC</replaceable>]</varname></term>
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<listitem>
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<para>Specifies naming policies applied when renaming network interfaces. Takes a list of
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policies and an optional MAC address separated with comma. Each policy value must be one of
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the policies understood by the <varname>NamePolicy=</varname> setting in .link files, e.g.
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<literal>onboard</literal> or <literal>path</literal>. See
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<citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more details. When the MAC address is specified, the policies are applied to the
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interface which has the address. When no MAC address is specified, the policies are applied
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to all interfaces. This kernel command line argument can be specified multiple times.</para>
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<para>This argument is not directly read by <command>systemd-udevd</command>, but is instead
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converted to a .link file by
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<citerefentry><refentrytitle>systemd-network-generator.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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For this argument to take effect, <filename>systemd-network-generator.service</filename> must be
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enabled.</para>
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<para>Example:
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<programlisting>net.ifname_policy=keep,kernel,path,slot,onboard,01:23:45:67:89:ab
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net.ifname_policy=keep,kernel,path,slot,onboard,mac</programlisting>
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This is mostly equivalent to creating the following .link files:
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<programlisting># 91-name-policy-with-mac.link
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[Match]
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MACAddress=01:23:45:67:89:ab
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[Link]
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NamePolicy=keep kernel path slot onboard
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AlternativeNamePolicy=path slot onboard</programlisting>
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and
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<programlisting># 92-name-policy-for-all.link
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[Match]
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OriginalName=*
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[Link]
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NamePolicy=keep kernel path slot onboard mac
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AlternativeNamePolicy=path slot onboard mac</programlisting>
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</para>
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<xi:include href="version-info.xml" xpointer="v250"/>
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</listitem>
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</varlistentry>
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</variablelist>
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<!-- when adding entries here, consider also adding them in kernel-command-line.xml -->
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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