Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 722 insertions, 0 deletions

diff --git a/man/kernel-install.xml b/man/kernel-install.xml
new file mode 100644
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--- /dev/null
+++ b/man/kernel-install.xml
@@ -0,0 +1,722 @@
+<?xml version='1.0'?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="kernel-install" conditional='ENABLE_KERNEL_INSTALL'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <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 initrd images to and from /boot</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <cmdsynopsis>
+      <command>kernel-install</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">add</arg>
+      <arg choice="plain"><replaceable>KERNEL-VERSION</replaceable></arg>
+      <arg choice="plain"><replaceable>KERNEL-IMAGE</replaceable></arg>
+      <arg choice="opt" rep="repeat"><replaceable>INITRD-FILE</replaceable></arg>
+    </cmdsynopsis>
+    <cmdsynopsis>
+      <command>kernel-install</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">remove</arg>
+      <arg choice="plain"><replaceable>KERNEL-VERSION</replaceable></arg>
+    </cmdsynopsis>
+    <cmdsynopsis>
+      <command>kernel-install</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">inspect</arg>
+      <arg choice="opt"><replaceable>KERNEL-VERSION</replaceable></arg>
+      <arg choice="opt"><replaceable>KERNEL-IMAGE</replaceable></arg>
+      <arg choice="opt" rep="repeat"><replaceable>INITRD-FILE</replaceable></arg>
+    </cmdsynopsis>
+    <cmdsynopsis>
+      <command>kernel-install</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">list</arg>
+    </cmdsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+    <para><command>kernel-install</command> is used to install and remove kernel and initrd images
+    <footnote>
+      <para>Nowadays actually CPIO archives used as an "initramfs", rather than "initrd". See
+      <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for an
+      explanation.</para>
+    </footnote>
+    to and from the boot loader partition, referred to as <varname>$BOOT</varname> here. It will usually be
+    one of <filename>/boot/</filename>, <filename>/efi/</filename>, or <filename>/boot/efi/</filename>, see
+    below.</para>
+
+    <para><command>kernel-install</command> will run the executable files ("plugins") 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 placed in these directories 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>] [<replaceable>INITRD-FILE</replaceable> ...]]</command>
+        </term>
+
+        <listitem>
+          <para>This command takes a kernel version string and a path to a kernel image file as arguments. If
+          the former is omitted, specified as an empty string or as "-" it defaults to the current kernel
+          version, i.e. the same string <command>uname -r</command> returns. If the latter is omitted,
+          specified as an empty string or as "-" defaults to
+          <filename>/usr/lib/modules/<replaceable>KERNEL_VERSION</replaceable>/vmlinuz</filename>. Optionally,
+          one or more initrd images may be specified as well (note that plugins might generate additional
+          ones).</para>
+
+          <para>The executable files from <filename>/usr/lib/kernel/install.d/*.install</filename> and
+          <filename>/etc/kernel/install.d/*.install</filename> (i.e. the plugins) are called with the
+          following arguments:</para>
+
+          <programlisting>add <replaceable>KERNEL-VERSION</replaceable> <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename> <replaceable>KERNEL-IMAGE</replaceable> \
+          [<replaceable>INITRD-FILE</replaceable> ...]</programlisting>
+
+          <para>The third argument directly refers to the path where to place kernel images, initrd
+          images and other resources for
+          <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot
+          Loader Specification</ulink> Type #1 entries (the "entry directory"). If other boot loader schemes
+          are used the parameter may be ignored.</para>
+
+          <para>The <replaceable>ENTRY-TOKEN</replaceable> string is typically the machine ID and is supposed
+          to identify the local installation on the system. For details see below.</para>
+
+          <para>Two default plugins execute the following operations in this case:</para>
+
+          <itemizedlist>
+            <listitem><para><command>kernel-install</command> creates
+            <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable></filename>,
+            if enabled (see <varname>$KERNEL_INSTALL_LAYOUT</varname>).</para></listitem>
+
+            <listitem><para><filename>50-depmod.install</filename> runs
+            <citerefentry project='man-pages'><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>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/linux</filename>.
+            If <replaceable>INITRD-FILE</replaceable>s are provided, it also copies them to
+            <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL_VERSION</replaceable>/<replaceable>INITRD-FILE</replaceable></filename>.
+            This can also be used to prepend microcode before the actual initrd. It also creates a boot loader entry according to the <ulink
+            url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink> (Type #1) in
+            <filename>$BOOT/loader/entries/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.
+            The title of the entry is the <replaceable>PRETTY_NAME</replaceable> parameter specified in
+            <filename>/etc/os-release</filename> or <filename>/usr/lib/os-release</filename> (if the former
+            is missing), or "Linux <replaceable>KERNEL-VERSION</replaceable>", if unset.</para>
+
+            <para>If <varname>$KERNEL_INSTALL_LAYOUT</varname> is not "bls", this plugin does nothing.</para></listitem>
+
+            <listitem><para><filename>90-uki-copy.install</filename> copies a file
+            <filename>uki.efi</filename> from <varname>$KERNEL_INSTALL_STAGING_AREA</varname> or if it does
+            not exist the <replaceable>KERNEL-IMAGE</replaceable> argument, only if it has a
+            <literal>.efi</literal> extension, to
+            <filename>$BOOT/EFI/Linux/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.efi</filename>.</para>
+
+            <para>If <varname>$KERNEL_INSTALL_LAYOUT</varname> is not "uki", this plugin does nothing.</para></listitem>
+          </itemizedlist>
+
+            <xi:include href="version-info.xml" xpointer="v198"/>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term>
+          <command>add-all</command>
+        </term>
+
+        <listitem>
+          <para>This is the same as <command>add</command> (see above), but invokes the operation iteratively
+          for every installed kernel in <filename>/usr/lib/modules/</filename>. This operation is only
+          supported on systems where the kernel image is installed in
+          <filename>/usr/lib/modules/<replaceable>KERNEL-VERSION</replaceable>/vmlinuz</filename>.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><command>remove <replaceable>KERNEL-VERSION</replaceable></command></term>
+        <listitem>
+          <para>This command expects a kernel version string as single argument.</para>
+
+          <para>The executable files from <filename>/usr/lib/kernel/install.d/*.install</filename> and
+          <filename>/etc/kernel/install.d/*.install</filename> (i.e. the plugins) are called with the
+          following arguments:</para>
+
+          <programlisting>remove <replaceable>KERNEL-VERSION</replaceable> <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename></programlisting>
+
+          <para>Afterwards, <command>kernel-install</command> removes the entry directory
+          <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename>
+          and its contents, if it exists.</para>
+
+          <para>Two default plugins execute the following operations in this case:</para>
+
+          <itemizedlist>
+            <listitem><para><filename>50-depmod.install</filename> removes the files generated by
+            <command>depmod</command> for this kernel again.</para></listitem>
+
+            <listitem><para><filename>90-loaderentry.install</filename> removes the file
+            <filename>$BOOT/loader/entries/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.conf</filename>.
+            </para></listitem>
+
+            <listitem><para><filename>90-uki-copy.install</filename> removes the file
+            <filename>$BOOT/EFI/Linux/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>.efi</filename>.
+            </para></listitem>
+          </itemizedlist>
+
+            <xi:include href="version-info.xml" xpointer="v198"/>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term>
+          <command>inspect [[[<replaceable>KERNEL-VERSION</replaceable>] <replaceable>KERNEL-IMAGE</replaceable>] [<replaceable>INITRD-FILE</replaceable> ...]]</command>
+        </term>
+        <listitem>
+          <para>Takes the same parameters as <command>add</command>.</para>
+
+          <para>Shows the various paths and parameters configured or auto-detected. In particular shows the
+          values of the various <varname>$KERNEL_INSTALL_*</varname> environment variables listed below, as
+          they would be passed to plugins. The <option>--json</option> option can be used to get the output
+          of this verb as a JSON object.</para>
+
+          <xi:include href="version-info.xml" xpointer="v251"/>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><command>list</command></term>
+        <listitem>
+          <para>Shows the various installed kernels. This enumerates the subdirectories of
+          <filename>/usr/lib/modules/</filename>, and shows whether a kernel image is installed there.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Compatibility with the kernel build system</title>
+
+    <cmdsynopsis>
+      <command>installkernel</command>
+      <arg choice="opt" rep="repeat">OPTIONS</arg>
+      <arg choice="plain">VERSION</arg>
+      <arg choice="plain">VMLINUZ</arg>
+      <arg choice="opt">MAP</arg>
+      <arg choice="opt">INSTALLATION-DIR</arg>
+    </cmdsynopsis>
+
+    <para>When invoked as <command>installkernel</command>, this program accepts arguments as specified by
+    the kernel build system's <command>make install</command> command. The <parameter>VERSION</parameter> and
+    <parameter>VMLINUZ</parameter> parameters specify the kernel version and the kernel binary. The other two
+    parameters (<parameter>MAP</parameter> and <parameter>INSTALLATION-DIR</parameter>) are currently
+    ignored.
+    </para>
+  </refsect1>
+
+  <refsect1>
+    <title>The <varname>$BOOT</varname> partition</title>
+
+    <para>The partition where the kernels and <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot
+    Loader Specification</ulink> snippets are located is called <varname>$BOOT</varname>.
+    <command>kernel-install</command> determines the location of this partition by checking
+    <filename>/efi/</filename>, <filename>/boot/</filename>, and <filename>/boot/efi/</filename> in turn. The
+    first location where <filename>$BOOT/loader/entries/</filename> or
+    <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/</filename> exists is used.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Options</title>
+    <para>The following options are understood:</para>
+
+    <variablelist>
+      <xi:include href="standard-options.xml" xpointer="esp-path"/>
+      <xi:include href="standard-options.xml" xpointer="boot-path"/>
+
+      <varlistentry>
+        <term><option>--make-entry-directory=yes|no|auto</option></term>
+        <listitem>
+          <para>Controls creation and deletion of the
+          <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink>
+          Type #1 entry directory on the file system containing resources such as kernel and initrd images
+          during <option>add</option> and <option>remove</option>, respectively. The directory is named after
+          the entry token, and is placed immediately below the boot root directory. When
+          <literal>auto</literal>, the directory is created or removed only when the install layout is
+          <literal>bls</literal>. Defaults to <literal>auto</literal>.</para>
+
+          <xi:include href="version-info.xml" xpointer="v254"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--entry-token=</option></term>
+
+        <listitem>
+          <para>Controls how to name and identify boot loader entries for this kernel installation or
+          deletion. Takes one of <literal>auto</literal>, <literal>machine-id</literal>,
+          <literal>os-id</literal>, <literal>os-image-id</literal>, or an arbitrary string prefixed by
+          <literal>literal:</literal> as argument.</para>
+
+          <para>If set to <option>machine-id</option> the entries are named after the machine ID of the
+          running system (e.g. <literal>b0e793a9baf14b5fa13ecbe84ff637ac</literal>). See
+          <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
+          details about the machine ID concept and file.</para>
+
+          <para>If set to <option>os-id</option> the entries are named after the OS ID of the running system,
+          i.e. the <varname>ID=</varname> field of
+          <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+          (e.g. <literal>fedora</literal>). Similarly, if set to <option>os-image-id</option> the entries are
+          named after the OS image ID of the running system, i.e. the <varname>IMAGE_ID=</varname> field of
+          <filename>os-release</filename> (e.g. <literal>vendorx-cashier-system</literal>).</para>
+
+          <para>If set to <option>auto</option> (the default), the
+          <filename>/etc/kernel/entry-token</filename> (or
+          <filename>$KERNEL_INSTALL_CONF_ROOT/entry-token</filename>) file will be read if it exists, and the
+          stored value used. Otherwise if the local machine ID is initialized it is used. Otherwise
+          <varname>IMAGE_ID=</varname> from <filename>os-release</filename> will be used, if set. Otherwise,
+          <varname>ID=</varname> from <filename>os-release</filename> will be used, if set. Otherwise a
+          randomly generated machine ID is used.</para>
+
+          <para>Using the machine ID for naming the entries is generally preferable, however there are cases
+          where using the other identifiers is a good option. Specifically: if the identification data that
+          the machine ID entails shall not be stored on the (unencrypted) <varname>$BOOT_ROOT</varname>
+          partition, or if the ID shall be generated on first boot and is not known when the entries are
+          prepared. Note that using the machine ID has the benefit that multiple parallel installations of
+          the same OS can coexist on the same medium, and they can update their boot loader entries
+          independently. When using another identifier (such as the OS ID or the OS image ID), parallel
+          installations of the same OS would try to use the same entry name. To support parallel
+          installations, the installer must use a different entry token when adding a second installation.
+          </para>
+
+          <xi:include href="version-info.xml" xpointer="v254"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>-v</option></term>
+        <term><option>--verbose</option></term>
+        <listitem>
+          <para>Output additional information about operations being performed.</para>
+
+        <xi:include href="version-info.xml" xpointer="v242"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--root=<replaceable>root</replaceable></option></term>
+
+        <listitem><para>Takes a directory path as an argument. All paths will be prefixed with the given
+        alternate <replaceable>root</replaceable> path, including config search paths. This is useful to
+        operate on a system image mounted to the specified directory instead of the host system
+        itself.</para>
+
+        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><option>--image=<replaceable>image</replaceable></option></term>
+
+        <listitem><para>Takes a path to a disk image file or block device node. If specified, all operations
+        are applied to the file system in the indicated disk image. This option is similar to
+        <option>--root=</option>, but operates on file systems stored in disk images or block devices. The
+        disk image should either contain just a file system or a set of file systems within a GPT partition
+        table, following the <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions
+        Specification</ulink>. For further information on supported disk images, see
+        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+        switch of the same name.</para>
+
+        <xi:include href="version-info.xml" xpointer="v255"/></listitem>
+      </varlistentry>
+
+      <xi:include href="standard-options.xml" xpointer="help" />
+      <xi:include href="standard-options.xml" xpointer="version" />
+      <xi:include href="standard-options.xml" xpointer="no-pager"/>
+      <xi:include href="standard-options.xml" xpointer="json" />
+      <xi:include href="standard-options.xml" xpointer="image-policy-open" />
+      <xi:include href="standard-options.xml" xpointer="no-legend"/>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Environment variables</title>
+
+    <refsect2>
+      <title>Environment variables exported for plugins</title>
+
+      <para>If <option>--verbose</option> is used, <varname>$KERNEL_INSTALL_VERBOSE=1</varname> will be
+      exported for plugins. They may output additional logs in this case.</para>
+
+      <para><varname>$KERNEL_INSTALL_IMAGE_TYPE=uki|pe|unknown</varname> is set for the plugins to specify the
+      type of the kernel image.</para>
+
+      <variablelist>
+        <varlistentry>
+          <term>uki</term>
+          <listitem>
+            <para>Unified kernel image.</para>
+
+            <xi:include href="version-info.xml" xpointer="v254"/>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>pe</term>
+          <listitem>
+            <para>PE binary.</para>
+
+            <xi:include href="version-info.xml" xpointer="v254"/>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>unknown</term>
+          <listitem>
+            <para>Unknown type.</para>
+
+            <xi:include href="version-info.xml" xpointer="v254"/>
+          </listitem>
+        </varlistentry>
+      </variablelist>
+
+      <para><varname>$KERNEL_INSTALL_MACHINE_ID</varname> is set for the plugins to the desired machine-id to
+      use. It's always a 128-bit ID. Normally it's read from <filename>/etc/machine-id</filename>, but it can
+      also be overridden via <varname>$MACHINE_ID</varname> (see below). If not specified via these methods,
+      a fallback value will generated by <command>kernel-install</command> and used only for a single
+      invocation.</para>
+
+      <para><varname>$KERNEL_INSTALL_ENTRY_TOKEN</varname> is set for the plugins to the desired entry
+      "token" to use. It's an identifier that shall be used to identify the local installation, and is often
+      the machine ID, i.e. same as <varname>$KERNEL_INSTALL_MACHINE_ID</varname>, but might also be a
+      different type of identifier, for example a fixed string or the <varname>ID=</varname>,
+      <varname>IMAGE_ID=</varname> values from <filename>/etc/os-release</filename>. The string passed here
+      will be used to name Boot Loader Specification entries, or the directories the kernel image and initial
+      RAM disk images are placed into.</para>
+
+      <para>Note that while <varname>$KERNEL_INSTALL_ENTRY_TOKEN</varname> and
+      <varname>$KERNEL_INSTALL_MACHINE_ID</varname> are often set to the same value, the latter is guaranteed
+      to be a valid 32 character ID in lowercase hexadecimals while the former can be any short string. The
+      entry token to use is read from <filename>/etc/kernel/entry-token</filename>, if it exists. Otherwise a
+      few possible candidates below <varname>$BOOT</varname> are checked for Boot Loader Specification Type 1
+      entry directories, and if found the entry token is derived from that. If that is not successful,
+      <varname>$KERNEL_INSTALL_MACHINE_ID</varname> is used as fallback.</para>
+
+      <para><varname>$KERNEL_INSTALL_BOOT_ROOT</varname> is set for the plugins to the absolute path of the
+      root directory (mount point, usually) of the hierarchy where boot loader entries, kernel images, and
+      associated resources should be placed. This usually is the path where the XBOOTLDR partition or the ESP
+      (EFI System Partition) are mounted, and also conceptually referred to as <varname>$BOOT</varname>. Can
+      be overridden by setting <varname>$BOOT_ROOT</varname> (see below).</para>
+
+      <para><varname>$KERNEL_INSTALL_LAYOUT=auto|bls|uki|other|...</varname> is set for the plugins to specify the
+      installation layout. Additional layout names may be defined by convention. If a plugin uses a special layout,
+      it's encouraged to declare its own layout name and configure <varname>layout=</varname> in
+      <filename>install.conf</filename> upon initial installation. The following values are currently
+      understood:</para>
+
+      <variablelist>
+        <varlistentry>
+          <term>bls</term>
+          <listitem>
+            <para>Standard <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader
+            Specification</ulink> Type #1 layout, compatible with
+            <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>:
+            entries in
+            <filename>$BOOT/loader/entries/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>[+<replaceable>TRIES</replaceable>].conf</filename>,
+            kernel and initrds under
+            <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable>/<replaceable>KERNEL-VERSION</replaceable>/</filename></para>
+            <para>Implemented by <filename>90-loaderentry.install</filename>.</para>
+
+            <xi:include href="version-info.xml" xpointer="v250"/>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>uki</term>
+          <listitem>
+            <para>Standard <ulink
+            url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader
+            Specification</ulink> Type #2 layout, compatible with
+            <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>:
+            unified kernel images under <filename>$BOOT/EFI/Linux</filename> as
+            <filename>$BOOT/EFI/Linux/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>[+<replaceable>TRIES</replaceable>].efi</filename>.</para>
+            <para>Implemented by <filename>90-uki-copy.install</filename>.</para>
+
+            <xi:include href="version-info.xml" xpointer="v253"/>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>other</term>
+          <listitem>
+            <para>Some other layout not understood natively by <command>kernel-install</command>.</para>
+
+          <xi:include href="version-info.xml" xpointer="v250"/>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
+          <term>auto</term>
+          <listitem>
+            <para>Pick the layout automatically. If the kernel is a UKI set layout to
+            <option>uki</option>. If not default to <option>bls</option> if
+            <filename>$BOOT/loader/entries.srel</filename> with content <literal>type1</literal> or
+            <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable></filename> exists, or
+            <option>other</option> otherwise.</para>
+            <para>Leaving layout blank has the same effect. This is the default.</para>
+
+            <xi:include href="version-info.xml" xpointer="v254"/>
+          </listitem>
+        </varlistentry>
+      </variablelist>
+
+      <para><varname>$KERNEL_INSTALL_INITRD_GENERATOR</varname> and <varname>$KERNEL_INSTALL_UKI_GENERATOR</varname>
+      are set for plugins to select the initrd and/or UKI generator. This may be configured as
+      <varname>initrd_generator=</varname> and <varname>uki_generator=</varname> in <filename>install.conf</filename>, see below.</para>
+
+      <para><varname>$KERNEL_INSTALL_STAGING_AREA</varname> is set for plugins to a path to a directory.
+      Plugins may drop files in that directory, and they will be installed as part of the loader entry, based
+      on the file name and extension: Files named <filename>initrd*</filename> will be installed as <replaceable>INITRD-FILE</replaceable>s,
+      and files named <filename>microcode*</filename> will be prepended before <replaceable>INITRD-FILE</replaceable>s.</para>
+
+    </refsect2>
+
+    <refsect2>
+      <title>Environment variables understood by <command>kernel-install</command></title>
+
+      <para><varname>$KERNEL_INSTALL_CONF_ROOT</varname> can be set to override the location of the
+      configuration files read by <command>kernel-install</command>. When set,
+      <filename>install.conf</filename>, <filename>entry-token</filename>, and other files will be
+      read from this directory.</para>
+
+      <para><varname>$KERNEL_INSTALL_PLUGINS</varname> can be set to override the list of plugins executed by
+      <command>kernel-install</command>. The argument is a whitespace-separated list of paths.
+      <literal>KERNEL_INSTALL_PLUGINS=:</literal> may be used to prevent any plugins from running.
+      </para>
+
+      <para><varname>$MACHINE_ID</varname> can be set for <command>kernel-install</command> to override
+      <varname>$KERNEL_INSTALL_MACHINE_ID</varname>, the machine ID.</para>
+
+      <para><varname>$BOOT_ROOT</varname> can be set for <command>kernel-install</command> to override
+      <varname>$KERNEL_INSTALL_BOOT_ROOT</varname>, the installation location for boot entries.</para>
+
+      <para>The last two variables may also be set in <filename>install.conf</filename>. Variables set in the
+      environment take precedence over the values specified in the config file.</para>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Exit status</title>
+    <para>If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Files</title>
+    <variablelist>
+      <varlistentry>
+        <term><filename>/etc/kernel/install.d/*.install</filename></term>
+        <term><filename>/usr/lib/kernel/install.d/*.install</filename></term>
+        <listitem>
+          <para>Drop-in files which are executed by <command>kernel-install</command>.</para>
+
+          <xi:include href="version-info.xml" xpointer="v198"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/etc/kernel/cmdline</filename></term>
+        <term><filename>/usr/lib/kernel/cmdline</filename></term>
+        <term><filename>/proc/cmdline</filename></term>
+        <listitem>
+          <para>Specifies the kernel command line to use. The first of the files that is found will be used.
+          <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be used to override the search path; see below for
+          details.</para>
+
+          <xi:include href="version-info.xml" xpointer="v198"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/etc/kernel/devicetree</filename></term>
+        <term><filename>/usr/lib/kernel/devicetree</filename></term>
+        <listitem>
+          <para>Specifies the partial path to the file containing the device tree blob to install with the
+          kernel and use at boot. The first of the files that is found will be used.
+          <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be used to override the search path; see below for
+          details.</para>
+
+          <para>The <filename>devicetree</filename> file contains a path, and this path specifies a location
+          relative to the kernel install tree. A set of locations is checked, including in particular
+          <filename>/usr/lib/modules/<replaceable>KERNEL_VERSION</replaceable>/dtb/</filename>, which is the
+          recommended location to place the dtb files under. For example, with
+          <literal>broadcom/bcm2711-rpi-4-b.dtb</literal> in the <filename>devicetree</filename> file, the
+          device tree blob for the Raspberry Pi 4 Model B would be installed, and the actual file would be
+          <filename index='false'>/usr/lib/modules/<replaceable>KERNEL_VERSION</replaceable>/dtb/broadcom/bcm2711-rpi-4-b.dtb</filename>.
+          </para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/etc/kernel/tries</filename></term>
+        <listitem>
+          <para>Read by <filename>90-loaderentry.install</filename> and
+          <filename>90-uki-copy.install</filename>. If this file exists, a numeric value is read from it and
+          the naming of the generated entry file or UKI is altered to include it as
+          <filename>$BOOT/loader/entries/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>+<replaceable>TRIES</replaceable>.conf</filename>
+          or
+          <filename>$BOOT/EFI/Linux/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>+<replaceable>TRIES</replaceable>.efi</filename>,
+          respectively. This is useful for boot loaders such as
+          <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+          which implement boot attempt counting with a counter embedded in the entry file name.
+          <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be used to override the search path; see below for
+          details.</para>
+
+          <xi:include href="version-info.xml" xpointer="v240"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/etc/kernel/entry-token</filename></term>
+        <listitem>
+          <para>If this file exists it is read and used as "entry token" for this system, i.e. is used for
+          naming Boot Loader Specification entries. See <varname>$KERNEL_INSTALL_ENTRY_TOKEN</varname> above
+          for details. <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be used to override the search path; see
+          below for details.</para>
+
+          <xi:include href="version-info.xml" xpointer="v251"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term>
+          <filename>/etc/machine-id</filename>
+        </term>
+          <listitem>
+            <para>The content of this file specifies the machine identification
+            <replaceable>MACHINE-ID</replaceable>.</para>
+
+            <xi:include href="version-info.xml" xpointer="v198"/>
+          </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/etc/os-release</filename></term>
+        <term><filename>/usr/lib/os-release</filename></term>
+        <listitem>
+            <para>Read by <filename>90-loaderentry.install</filename>. If available,
+            <varname>PRETTY_NAME=</varname> is read from these files and used as the title of the boot menu
+            entry. Otherwise, <literal>Linux <replaceable>KERNEL-VERSION</replaceable></literal> will be
+            used.</para>
+
+            <xi:include href="version-info.xml" xpointer="v198"/>
+          </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><filename>/etc/kernel/install.conf</filename></term>
+        <term><filename>/usr/lib/kernel/install.conf</filename></term>
+        <listitem>
+          <para>Configuration file with options for <command>kernel-install</command>, as a series of
+          <varname>KEY=</varname><replaceable>VALUE</replaceable> assignments, compatible with shell syntax,
+          following the same rules as described in
+          <citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
+          first of the files that is found will be used. <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be
+          used to override the search path; see below for details.</para>
+
+          <para>Currently, the following keys are supported:
+          <varname>MACHINE_ID=</varname>,
+          <varname>BOOT_ROOT=</varname>,
+          <varname>layout=</varname>,
+          <varname>initrd_generator=</varname>,
+          <varname>uki_generator=</varname>.
+          See the Environment variables section above for details.</para>
+
+          <xi:include href="version-info.xml" xpointer="v250"/>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><filename>/etc/kernel/uki.conf</filename></term>
+        <listitem>
+          <para>Ini-style configuration file for
+          <citerefentry><refentrytitle>ukify</refentrytitle><manvolnum>1</manvolnum></citerefentry> which is
+          only effective when <varname>$KERNEL_INSTALL_LAYOUT</varname> or <varname>layout=</varname> in
+          <filename>install.conf</filename> is set to <option>uki</option> and
+          <varname>$KERNEL_INSTALL_UKI_GENERATOR</varname> or <varname>uki_generator=</varname> in
+          <filename>install.conf</filename> is set to <option>ukify</option>, or is unset.
+          <varname>$KERNEL_INSTALL_CONF_ROOT</varname> may be used to override the search path; see below for
+          details.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/usr/lib/modules/<replaceable>KERNEL-VERSION/</replaceable></filename></term>
+
+        <listitem>
+          <para>Location for installed kernel modules and other kernel related resources. For each locally
+          installed kernel a directory named after the kernel version (<command>uname -r</command>) is
+          kept.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><filename>/usr/lib/modules/<replaceable>KERNEL-VERSION/vmlinuz</replaceable></filename></term>
+
+        <listitem>
+          <para>Location for installed kernel images. This is the recommended location for OS package
+          managers to install kernel images into (as applicable), from which <command>kernel-install
+          add</command> then copies it into the final boot partition.</para>
+
+          <xi:include href="version-info.xml" xpointer="v255"/>
+        </listitem>
+      </varlistentry>
+
+    </variablelist>
+
+    <para>For various cases listed above, if the <varname>$KERNEL_INSTALL_CONF_ROOT</varname> environment
+    variable is set, it will override the search path. The files will be loaded <emphasis>only</emphasis>
+    from the directory specified by the environment variable. When the variable is not set, the listed paths
+    are tried in turn, and the first file that exists is used.</para>
+  </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 project='man-pages'><refentrytitle>depmod</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>ukify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <ulink url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader Specification</ulink>
+    </para>
+  </refsect1>
+
+</refentry>