kernel-install: fix dracut initrd detection (240 backward compatibility) (#11570)

* kernel-install: fix initrd when called as installkernel

Running make install from the kernel runs e.g.:
installkernel 4.20.5 arch/x86/boot/bzImage System.map "/boot"

Since 0912c0b80eb24fb9a4e1cc4abf274a1358b9943d this would
cal 90-loaderentry.install with those arguments:
add 4.20.5 /boot/... arch/x86/boot/bzImage System.map "/boot"

The two last arguments would then be handled as the initrd files.
As System.map exists in current directory but not in /boot/...
it would get copied there, and used as initrd intead of the initrd
which has been generated by dracut.

With this change, nothing changes when kernel-install is called
directly, but when it's called as installkernel, we now pass
thos arguments to 90-loaderentry.install:
add 4.20.5 /boot/... arch/x86/boot/bzImage initrd
initrd is thus detected as the file to use for the initrd, and as it
exists, nothing is copied over and the initrd line generated is
consistent with what one would expect

* kernel-install: fix dracut initrd detection when called directly

This brings back the systemd 240 behaviour when called directly too

* kernel-install: unify initrd fallback

* kernel-install: move initrd fallback handling to 90-loaderentry.install

* kernel-install: move initrd fallback just before creating loader entry

2 files changed, 12 insertions, 4 deletions

diff --git a/src/kernel-install/90-loaderentry.install b/src/kernel-install/90-loaderentry.install
index e5fb232f35..75dd5a1b7d 100644
--- a/src/kernel-install/90-loaderentry.install
+++ b/src/kernel-install/90-loaderentry.install
@@ -83,7 +83,9 @@ cp "$KERNEL_IMAGE" "$BOOT_DIR_ABS/linux" &&
     exit 1
 }
 
-for initrd in "${@:${INITRD_OPTIONS_START}}"; do
+INITRD_OPTIONS=( "${@:${INITRD_OPTIONS_START}}" )
+
+for initrd in "${INITRD_OPTIONS[@]}"; do
     if [[ -f "${initrd}" ]]; then
         initrd_basename="$(basename ${initrd})"
         cp "${initrd}" "$BOOT_DIR_ABS/${initrd_basename}" &&
@@ -95,6 +97,10 @@ for initrd in "${@:${INITRD_OPTIONS_START}}"; do
     fi
 done
 
+# If no initrd option is supplied, fallback to "initrd" which is
+# the name used by dracut when generating it in its kernel-install hook
+[[ ${#INITRD_OPTIONS[@]} == 0 ]] && INITRD_OPTIONS=( initrd )
+
 mkdir -p "${LOADER_ENTRY%/*}" || {
     echo "Could not create loader entry directory '${LOADER_ENTRY%/*}'." >&2
     exit 1
@@ -106,7 +112,7 @@ mkdir -p "${LOADER_ENTRY%/*}" || {
     echo "machine-id $MACHINE_ID"
     echo "options    ${BOOT_OPTIONS[*]}"
     echo "linux      $BOOT_DIR/linux"
-    for initrd in "${@:${INITRD_OPTIONS_START}}"; do
+    for initrd in "${INITRD_OPTIONS[@]}"; do
         [[ -f $BOOT_DIR_ABS/$(basename ${initrd}) ]] && \
             echo "initrd     $BOOT_DIR/$(basename ${initrd})"
     done
diff --git a/src/kernel-install/kernel-install b/src/kernel-install/kernel-install
index 7973818bca..b85c7c557e 100644
--- a/src/kernel-install/kernel-install
+++ b/src/kernel-install/kernel-install
@@ -65,14 +65,16 @@ done
 
 if [[ "${0##*/}" == 'installkernel' ]]; then
     COMMAND='add'
+    # make install doesn't pass any parameter wrt initrd handling
+    INITRD_OPTIONS=()
 else
     COMMAND="$1"
     shift
+    INITRD_OPTIONS=( "${@:3}" )
 fi
 
 KERNEL_VERSION="$1"
 KERNEL_IMAGE="$2"
-INITRD_OPTIONS_START="3"
 
 if [[ -f /etc/machine-id ]]; then
     read MACHINE_ID < /etc/machine-id
@@ -124,7 +126,7 @@ case $COMMAND in
 
         for f in "${PLUGINS[@]}"; do
             if [[ -x $f ]]; then
-                "$f" add "$KERNEL_VERSION" "$BOOT_DIR_ABS" "$KERNEL_IMAGE" "${@:${INITRD_OPTIONS_START}}"
+                "$f" add "$KERNEL_VERSION" "$BOOT_DIR_ABS" "$KERNEL_IMAGE" "${INITRD_OPTIONS[@]}"
                 x=$?
                 if [[ $x == $SKIP_REMAINING ]]; then
                     ret=0