kernel-install: Add uki layout

Currently the kernel-install man page only documents the bls layout for use
with the boot loader spec type #1. 90-loaderentry.install uses this layout to
generate loader entries and copy the kernel image and initrd to $BOOT.

This commit documents a second layout "uki" and adds 90-uki-copy.install,
which copies a UKI "uki.efi" from the staging area or any file with the .efi
extension given on the command line to
$BOOT/EFI/Linux/$ENTRY_TOKEN-$KERNEl_VERSION(+$TRIES).efi

This allows for both locally generated and distro-provided UKIs to be handled
by kernel-install.

man/kernel-install.xml

@@ -108,6 +108,14 @@
             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, iff 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>
         </listitem>
       </varlistentry>
@@ -132,6 +140,9 @@
 
             <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>
         </listitem>
       </varlistentry>
@@ -213,7 +224,7 @@
       (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>$KERNEL_INSTALL_LAYOUT=bls|other|...</varname> is set for the plugins to specify the
+      <para><varname>$KERNEL_INSTALL_LAYOUT=bls|uki|other|...</varname> is set for the plugins to specify the
       installation layout. Defaults to <option>bls</option> if
       <filename>$BOOT/<replaceable>ENTRY-TOKEN</replaceable></filename> exists, or <option>other</option>
       otherwise. Additional layout names may be defined by convention. If a plugin uses a special layout,
@@ -235,6 +246,18 @@
             <para>Implemented by <filename>90-loaderentry.install</filename>.</para>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term>uki</term>
+          <listitem>
+            <para>Standard <ulink
+            url="https://uapi-group.org/specifications/specs/boot_loader_specification">Boot Loader
+            Specification</ulink> Type #2 layout, compatible with
+            <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>:
+            unified kernel images under <filename>$BOOT/EFI/Linux</filename> as
+            <filename>$BOOT/EFI/Linux/<replaceable>ENTRY-TOKEN</replaceable>-<replaceable>KERNEL-VERSION</replaceable>[+<replaceable>TRIES</replaceable>].efi</filename>.</para>
+            <para>Implemented by <filename>90-uki-copy.install</filename>.</para>
+          </listitem>
+        </varlistentry>
         <varlistentry>
           <term>other</term>
           <listitem>
@@ -312,12 +335,15 @@
           <filename>/etc/kernel/tries</filename>
         </term>
           <listitem>
-            <para>Read by <filename>90-loaderentry.install</filename>. If this file exists a numeric value is read from
+            <para>Read by <filename>90-loaderentry.install</filename> and
-            it and the naming of the generated entry file is slightly altered to include it as
+            <filename>90-uki-copy.install</filename>. If this file exists a numeric value is read from it
-            <filename>$BOOT/loader/entries/<replaceable>MACHINE-ID</replaceable>-<replaceable>KERNEL-VERSION</replaceable>+<replaceable>TRIES</replaceable>.conf</filename>. This
+            and the naming of the generated entry file or UKI is slightly 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>.conf</filename>, respectively. This
             is useful for boot loaders such as
-            <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry> which
+            <citerefentry><refentrytitle>systemd-boot</refentrytitle><manvolnum>7</manvolnum></citerefentry>
-            implement boot attempt counting with a counter embedded in the entry file name.
+            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 path.</para>
           </listitem>
       </varlistentry>

src/kernel-install/90-uki-copy.install

@@ -0,0 +1,97 @@
+#!/bin/sh
+# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
+# ex: ts=8 sw=4 sts=4 et filetype=sh
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# This file is part of systemd.
+#
+# systemd is free software; you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 of the License, or
+# (at your option) any later version.
+#
+# systemd is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with systemd; If not, see <https://www.gnu.org/licenses/>.
+
+set -e
+
+COMMAND="${1:?}"
+KERNEL_VERSION="${2:?}"
+# shellcheck disable=SC2034
+ENTRY_DIR_ABS="$3"
+KERNEL_IMAGE="$4"
+
+[ "$KERNEL_INSTALL_LAYOUT" = "uki" ] || exit 0
+
+ENTRY_TOKEN="$KERNEL_INSTALL_ENTRY_TOKEN"
+BOOT_ROOT="$KERNEL_INSTALL_BOOT_ROOT"
+
+UKI_DIR="$BOOT_ROOT/EFI/Linux"
+
+case "$COMMAND" in
+    remove)
+        [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && \
+            echo "Removing $UKI_DIR/$ENTRY_TOKEN-$KERNEL_VERSION*.efi"
+        exec rm -f \
+            "$UKI_DIR/$ENTRY_TOKEN-$KERNEL_VERSION.efi" \
+            "$UKI_DIR/$ENTRY_TOKEN-$KERNEL_VERSION+"*".efi"
+        ;;
+    add)
+        ;;
+    *)
+        exit 0
+        ;;
+esac
+
+if ! [ -d "$UKI_DIR" ]; then
+    echo "Error: entry directory '$UKI_DIR' does not exist" >&2
+    exit 1
+fi
+
+TRIES_FILE="${KERNEL_INSTALL_CONF_ROOT:-/etc/kernel}/tries"
+
+if [ -f "$TRIES_FILE" ]; then
+    read -r TRIES <"$TRIES_FILE"
+    if ! echo "$TRIES" | grep -q '^[0-9][0-9]*$'; then
+        echo "$TRIES_FILE does not contain an integer." >&2
+        exit 1
+    fi
+    UKI_FILE="$UKI_DIR/$ENTRY_TOKEN-$KERNEL_VERSION+$TRIES.efi"
+else
+    UKI_FILE="$UKI_DIR/$ENTRY_TOKEN-$KERNEL_VERSION.efi"
+fi
+
+# If there is a UKI named uki.efi on the staging area use that, if not use what
+# was passed in as $KERNEL_IMAGE but insist it has a .efi extension
+if [ -f "$KERNEL_INSTALL_STAGING_AREA/uki.efi" ]; then
+    [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && echo "Installing $KERNEL_INSTALL_STAGING_AREA/uki.efi"
+    install -m 0644 "$KERNEL_INSTALL_STAGING_AREA/uki.efi" "$UKI_FILE" || {
+        echo "Error: could not copy '$KERNEL_INSTALL_STAGING_AREA/uki.efi' to '$UKI_FILE'." >&2
+        exit 1
+    }
+elif [ -n "$KERNEL_IMAGE" ]; then
+    [ -f "$KERNEL_IMAGE" ] || {
+        echo "Error: UKI '$KERNEL_IMAGE' not a file." >&2
+        exit 1
+    }
+    [ "$KERNEL_IMAGE" != "${KERNEL_IMAGE%*.efi}.efi" ] && {
+        echo "Error: $KERNEL_IMAGE is missing .efi suffix." >&2
+        exit 1
+    }
+    [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && echo "Installing $KERNEL_IMAGE"
+    install -m 0644 "$KERNEL_IMAGE" "$UKI_FILE" || {
+        echo "Error: could not copy '$KERNEL_IMAGE' to '$UKI_FILE'." >&2
+        exit 1
+    }
+else
+    [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && echo "No UKI available. Nothing to do."
+    exit 0
+fi
+chown root:root "$UKI_FILE" || :
+
+exit 0

src/kernel-install/meson.build

@@ -12,6 +12,8 @@ loaderentry_install = custom_target(
         install_mode : 'rwxr-xr-x',
         install_dir : kernelinstalldir)
 
+uki_copy_install = files('90-uki-copy.install')
+
 if want_kernel_install
         install_data('50-depmod.install',
                      install_mode : 'rwxr-xr-x',