systemd/man/systemd-debug-generator.xml
Daan De Meyer 7bf52f5d1c Add systemd.default_debug_tty=
Let's allow configuring the debug tty independently of enabling/disabling
the debug shell. This allows mkosi to configure the correct tty while
leaving enabling/disabling the debug tty to the user.
2024-02-09 11:47:53 +01:00

83 lines
3.9 KiB
XML

<?xml version="1.0"?>
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-debug-generator">
<refentryinfo>
<title>systemd-debug-generator</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-debug-generator</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-debug-generator</refname>
<refpurpose>Generator for enabling a runtime debug shell and
masking specific units at boot</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/usr/lib/systemd/system-generators/systemd-debug-generator</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-debug-generator</filename> is a generator
that reads the kernel command line and understands three
options:</para>
<para>If the <option>systemd.mask=</option> or <option>rd.systemd.mask=</option>
option is specified and followed by a unit name, this unit is
masked for the runtime (i.e. for this session — from boot to shutdown), similarly to the effect of
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>mask</command> command. This is useful to boot with
certain units removed from the initial boot transaction for
debugging system startup. May be specified more than once.
<option>rd.systemd.mask=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.mask=</option> is
honored only in the main system.</para>
<para>If the <option>systemd.wants=</option> or
<option>rd.systemd.wants=</option> option is specified
and followed by a unit name, a start job for this unit is added to
the initial transaction. This is useful to start one or more
additional units at boot. May be specified more than once.
<option>rd.systemd.wants=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.wants=</option> is
honored only in the main system.</para>
<para>If the <option>systemd.debug_shell</option> or <option>rd.systemd.debug_shell</option> option is
specified, the debug shell service <literal>debug-shell.service</literal> is pulled into the boot
transaction and a debug shell will be spawned during early boot. By default,
<filename>&DEBUGTTY;</filename> is used, but a specific tty can also be specified, either with or without
the <filename>/dev/</filename> prefix. To set the tty to use without enabling the debug shell, the
<option>systemd.default_debug_tty=</option> option can be used which also takes a tty with or without the
<filename>/dev/</filename> prefix. Note that the shell may also be turned on persistently by enabling it
with <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>enable</command> command. <option>rd.systemd.debug_shell=</option> is honored only by initial
RAM disk (initrd) while <option>systemd.debug_shell</option> is honored only in the main system.</para>
<para><filename>systemd-debug-generator</filename> implements
<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>