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systemd/man/systemd-suspend.service.xml
Adrian Vovk 0b958bb3ee
sleep: Always freeze user.slice
Previously, we'd only freeze user.slice in the case of s2h, because we
didn't want the user session to resume while systemd was transitioning
from suspend to hibernate.

This commit extends this freezing behavior to all sleep modes.

We also have an environment variable to disable the freezing behavior
outright. This is a necessary workaround for someone that has hooks
in /usr/lib/systemd/system-sleep/ which communicate with some
process running under user.slice, or if someone is using the proprietary
NVIDIA driver which breaks when user.slice is frozen (issue #27559)

Fixes #27559
2024-03-05 12:12:35 -05:00

139 lines
6.6 KiB
XML

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-suspend.service"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-suspend.service</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-suspend.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-suspend.service</refname>
<refname>systemd-hibernate.service</refname>
<refname>systemd-hybrid-sleep.service</refname>
<refname>systemd-suspend-then-hibernate.service</refname>
<refname>systemd-sleep</refname>
<refpurpose>System sleep state logic</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><simplelist>
<member><filename>systemd-suspend.service</filename></member>
<member><filename>systemd-hibernate.service</filename></member>
<member><filename>systemd-hybrid-sleep.service</filename></member>
<member><filename>systemd-suspend-then-hibernate.service</filename></member>
<member><filename>/usr/lib/systemd/system-sleep</filename></member>
</simplelist></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-suspend.service</filename> is a system
service that is pulled in by <filename>suspend.target</filename>
and is responsible for the actual system suspend. Similarly,
<filename>systemd-hibernate.service</filename> is pulled in by
<filename>hibernate.target</filename> to execute the actual
hibernation. Finally,
<filename>systemd-hybrid-sleep.service</filename> is pulled in by
<filename>hybrid-sleep.target</filename> to execute hybrid
hibernation with system suspend and pulled in by
<filename>suspend-then-hibernate.target</filename> to execute system suspend
with a timeout that will activate hibernate later.</para>
<para>Immediately before entering system suspend and/or
hibernation <filename>systemd-suspend.service</filename> (and the
other mentioned units, respectively) will run all executables in
<filename>/usr/lib/systemd/system-sleep/</filename> and pass two
arguments to them. The first argument will be
<literal>pre</literal>, the second either
<literal>suspend</literal>, <literal>hibernate</literal>,
<literal>hybrid-sleep</literal>, or <literal>suspend-then-hibernate</literal>
depending on the chosen action. An environment variable called <literal>SYSTEMD_SLEEP_ACTION</literal>
will be set and contain the sleep action that is processing. This is primarily helpful for
<literal>suspend-then-hibernate</literal> where the value of the variable will be <literal>suspend</literal>, <literal>hibernate</literal>,
or <literal>suspend-after-failed-hibernate</literal> in cases where hibernation has failed.
Immediately after leaving system suspend and/or hibernation the
same executables are run, but the first argument is now
<literal>post</literal>. All executables in this directory are
executed in parallel, and execution of the action is not continued
until all executables have finished. Note that <filename>user.slice</filename> will
be frozen while the executables are running, so they should not attempt to
communicate with any user services expecting a reply.</para>
<para>Note that scripts or binaries dropped in
<filename>/usr/lib/systemd/system-sleep/</filename> are intended
for local use only and should be considered hacks. If applications
want to react to system suspend/hibernation and resume,
they should rather use the <ulink
url="https://www.freedesktop.org/wiki/Software/systemd/inhibit">Inhibitor
interface</ulink>.</para>
<para>Note that <filename>systemd-suspend.service</filename>,
<filename>systemd-hibernate.service</filename>, <filename>systemd-hybrid-sleep.service</filename>, and
<filename>systemd-suspend-then-hibernate.service</filename> should never be executed directly. Instead,
trigger system sleep with a command such as <command>systemctl suspend</command> or <command>systemctl
hibernate</command>.</para>
<para>Internally, this service will echo a string like
<literal>mem</literal> into <filename>/sys/power/state</filename>,
to trigger the actual system suspend. What exactly is written
where can be configured in the [Sleep] section
of <filename>/etc/systemd/sleep.conf</filename> or a
<filename>sleep.conf.d</filename> file. See
<citerefentry><refentrytitle>systemd-sleep.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>Note that by default these services freeze <filename>user.slice</filename> while they run. This prevents
the execution of any process in any of the user sessions while the system is entering into and resuming from
sleep. Thus, this prevents the hooks in <filename>/usr/lib/systemd/system-sleep/</filename>, or any other process
for that matter, from communicating with any user session process during sleep.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para><command>systemd-sleep</command> understands the
following commands:</para>
<variablelist>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
<varlistentry>
<term><option>suspend</option></term>
<term><option>hibernate</option></term>
<term><option>suspend-then-hibernate</option></term>
<term><option>hybrid-sleep</option></term>
<listitem><para>Suspend, hibernate, suspend then hibernate, or put the
system to hybrid sleep.</para>
<xi:include href="version-info.xml" xpointer="v203"/>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd-sleep.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd-halt.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>