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systemd-stable/man/kernel-install.xml
Lennart Poettering 4b2d80bb0a man: update kernel-install(8) documentation
Many general updates, but most importantly, document the
/etc/kernel/tries logic briefly.
2018-10-19 22:34:50 +02:00

201 lines
9.3 KiB
XML

<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1+
-->
<refentry id="kernel-install">
<refentryinfo>
<title>kernel-install</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>kernel-install</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>kernel-install</refname>
<refpurpose>Add and remove kernel and initramfs images to and from /boot</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>kernel-install</command>
<arg choice="plain">COMMAND</arg>
<arg choice="plain"><replaceable>KERNEL-VERSION</replaceable></arg>
<arg choice="opt"><replaceable>KERNEL-IMAGE</replaceable></arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>kernel-install</command> is used to install and remove kernel and
initramfs images to and from <filename>/boot</filename>.
</para>
<para><command>kernel-install</command> will execute the files
located in the directory <filename>/usr/lib/kernel/install.d/</filename>
and the local administration directory <filename>/etc/kernel/install.d/</filename>.
All files are collectively sorted and executed in lexical order, regardless of the directory in
which they live. However, files with identical filenames replace each other.
Files in <filename>/etc/kernel/install.d/</filename> take precedence over files with the same name
in <filename>/usr/lib/kernel/install.d/</filename>. This can be used to override a system-supplied
executables with a local file if needed; a symbolic link in <filename>/etc/kernel/install.d/</filename>
with the same name as an executable in <filename>/usr/lib/kernel/install.d/</filename>,
pointing to <filename>/dev/null</filename>, disables the executable entirely. Executables must have the
extension <literal>.install</literal>; other extensions are ignored.</para>
<para>An executable should return <constant>0</constant> on success. It may also
return <constant>77</constant> to cause the whole operation to terminate
(executables later in lexical order will be skipped).</para>
</refsect1>
<refsect1>
<title>Commands</title>
<para>The following commands are understood:</para>
<variablelist>
<varlistentry>
<term><command>add <replaceable>KERNEL-VERSION</replaceable> <replaceable>KERNEL-IMAGE</replaceable></command></term>
<listitem>
<para>This command expects a kernel version string and a path to a kernel image file as
arguments. <command>kernel-install</command> creates the directory
<filename>/boot/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
and calls the executables from <filename>/usr/lib/kernel/install.d/*.install</filename> and
<filename>/etc/kernel/install.d/*.install</filename> with the following arguments:
<programlisting>add <replaceable>KERNEL-VERSION</replaceable> <filename>/boot/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename> <replaceable>KERNEL-IMAGE</replaceable></programlisting>
</para>
<para>Two default plugins execute the following operations in this case:</para>
<itemizedlist>
<listitem><para><filename>50-depmod.install</filename> runs
<citerefentry><refentrytitle>depmod</refentrytitle><manvolnum>8</manvolnum></citerefentry> for the
<replaceable>KERNEL-VERSION</replaceable>.</para></listitem>
<listitem><para><filename>90-loaderentry.install</filename> copies <replaceable>KERNEL-IMAGE</replaceable>
to
<filename>/boot/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/linux</filename>.
It also creates a boot loader entry according to the <ulink
url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification</ulink> in
<filename>/boot/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.
The title of the entry is the <replaceable>PRETTY_NAME</replaceable> parameter specified in
<filename>/etc/os-release</filename> or <filename>/usr/lib/os-release</filename> (if the former is
missing), or "Linux <replaceable>KERNEL-VERSION</replaceable>", if unset. If the file
<filename>initrd</filename> is found next to the kernel image file, the initrd will be added to the
configuration.</para></listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term><command>remove <replaceable>KERNEL-VERSION</replaceable></command></term>
<listitem>
<para>This command expects a kernel version string as single argument. This calls executables from
<filename>/usr/lib/kernel/install.d/*.install</filename> and
<filename>/etc/kernel/install.d/*.install</filename> with the following arguments:
<programlisting>remove <replaceable>KERNEL-VERSION</replaceable> <filename>/boot/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename></programlisting>
</para>
<para>Afterwards, <command>kernel-install</command> removes the directory
<filename>/boot/<replaceable>MACHINE-ID</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
and its contents.</para>
<para>Two default plugins execute the following operations in this case:</para>
<itemizedlist>
<listitem><para><filename>50-depmod.install</filename> removes the files generated by <command>depmod</command> for this kernel again.</para></listitem>
<listitem><para><filename>90-loaderentry.install</filename> removes the file
<filename>/boot/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.</para></listitem>
</itemizedlist>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.</para>
</refsect1>
<refsect1>
<title>Files</title>
<variablelist>
<varlistentry>
<term>
<filename>/usr/lib/kernel/install.d/*.install</filename>
<filename>/etc/kernel/install.d/*.install</filename>
</term>
<listitem>
<para>Drop-in files which are executed by kernel-install.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<filename>/etc/kernel/cmdline</filename>
<filename>/proc/cmdline</filename>
</term>
<listitem>
<para>Read by <filename>90-loaderentry.install</filename>. The content of the file
<filename>/etc/kernel/cmdline</filename> specifies the kernel command line to use. If that file does not
exist, <filename>/proc/cmdline</filename> is used.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<filename>/etc/kernel/tries</filename>
</term>
<listitem>
<para>Read by <filename>90-loaderentry.install</filename>. If this file exists a numeric value is read from
it and the naming of the generated entry file is slightly altered to include it as
<filename>/boot/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>+<replaceable>TRIES</replaceable>.conf</filename>. This
is useful for boot loaders such as
<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> which
implement boot attempt counting with a counter embedded in the entry file name.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<filename>/etc/machine-id</filename>
</term>
<listitem>
<para>The content of the file specifies the machine identification <replaceable>MACHINE-ID</replaceable>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<filename>/etc/os-release</filename>
<filename>/usr/lib/os-release</filename>
</term>
<listitem>
<para>The content of the file specifies the operating system title <replaceable>PRETTY_NAME</replaceable>.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>depmod</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<ulink url="https://systemd.io/BOOT_LOADER_SPECIFICATION">Boot Loader Specification</ulink>
</para>
</refsect1>
</refentry>