[PATCH v2] Make generated initrd location configurable

[Kelvin Fan]

In the latest releases of Fedora CoreOS, the /boot
directory is mounted read-only. Instead of always placing the
generated kdump initrd next to the default initrd (which is
usually under /boot), make the generated initrd's location
configurable in `/etc/sysconfig/kdump`.

Signed-off by: Kelvin Fan <kfan(a)redhat.com&gt;
---
Changes v1 -> v2:
 - Fixed typo `ARGET_INITRD=` -> `TARGET_INITRD`

 kdump.sysconfig |  3 +++
 kdumpctl        | 12 +++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/kdump.sysconfig b/kdump.sysconfig
index 30f0c63..952d5c7 100644
--- a/kdump.sysconfig
+++ b/kdump.sysconfig
@@ -30,6 +30,9 @@ KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices
novmcoredd"
 #   KEXEC_ARGS="--elf32-core-headers"
 KEXEC_ARGS=""
 
+# Where to store the generated kdump initrd
+TARGET_INITRD_DIR=""
+
 #Where to find the boot image
 #KDUMP_BOOTDIR="/boot"
 
diff --git a/kdumpctl b/kdumpctl
index 24f5cf7..4df41b2 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -151,8 +151,9 @@ rebuild_kdump_initrd()
 
 rebuild_initrd()
 {
-	if [[ ! -w "$KDUMP_BOOTDIR" ]];then
-		derror "$KDUMP_BOOTDIR does not have write permission. Can not rebuild
$TARGET_INITRD"
+	TARGET_INITRD_DIR=$(dirname $TARGET_INITRD)
+	if [[ ! -w "$TARGET_INITRD_DIR" ]];then
+		derror "$TARGET_INITRD_DIR does not have write permission. Can not rebuild
$TARGET_INITRD"
 		return 1
 	fi
 
@@ -335,7 +336,12 @@ setup_initrd()
 		# with fadump aware initrd
 		backup_default_initrd
 	else
-		TARGET_INITRD="$KDUMP_INITRD"
+		if [ -z $TARGET_INITRD_DIR ]; then
+			TARGET_INITRD="$KDUMP_INITRD"
+		else
+			KDUMP_INITRD_BASE=$(basename "$KDUMP_INITRD")
+			TARGET_INITRD="$TARGET_INITRD_DIR"/"$KDUMP_INITRD_BASE"
+		fi
 
 		# check if a backup of default initrd exists. If yes,
 		# it signifies a switch from fadump mode. So, restore
-- 
2.29.2

[Kairui Song]

Hi Kelvin

On Wed, Feb 3, 2021 at 11:45 AM Kelvin Fan <kfan(a)redhat.com&gt; wrote:
>  In the latest releases of Fedora CoreOS, the /boot
>  directory is mounted read-only. Instead of always placing the
>  generated kdump initrd next to the default initrd (which is
>  usually under /boot), make the generated initrd's location
>  configurable in `/etc/sysconfig/kdump`.
>
>  Signed-off by: Kelvin Fan <kfan(a)redhat.com&gt;
>  ---
>  Changes v1 -> v2:
>   - Fixed typo `ARGET_INITRD=` -> `TARGET_INITRD`
>
>   kdump.sysconfig |  3 +++
>   kdumpctl        | 12 +++++++++---
>   2 files changed, 12 insertions(+), 3 deletions(-)
>
>  diff --git a/kdump.sysconfig b/kdump.sysconfig
>  index 30f0c63..952d5c7 100644
>  --- a/kdump.sysconfig
>  +++ b/kdump.sysconfig
>  @@ -30,6 +30,9 @@ KDUMP_COMMANDLINE_APPEND="irqpoll maxcpus=1 reset_devices
> novmcoredd"
>   #   KEXEC_ARGS="--elf32-core-headers"
>   KEXEC_ARGS=""
>
>  +# Where to store the generated kdump initrd
>  +TARGET_INITRD_DIR=""
>  +
>   #Where to find the boot image
>   #KDUMP_BOOTDIR="/boot"
>
>  diff --git a/kdumpctl b/kdumpctl
>  index 24f5cf7..4df41b2 100755
>  --- a/kdumpctl
>  +++ b/kdumpctl
>  @@ -151,8 +151,9 @@ rebuild_kdump_initrd()
>
>   rebuild_initrd()
>   {
>  -       if [[ ! -w "$KDUMP_BOOTDIR" ]];then
>  -               derror "$KDUMP_BOOTDIR does not have write permission. Can not
> rebuild $TARGET_INITRD"
>  +       TARGET_INITRD_DIR=$(dirname $TARGET_INITRD)
>  +       if [[ ! -w "$TARGET_INITRD_DIR" ]];then
>  +               derror "$TARGET_INITRD_DIR does not have write permission. Can not
> rebuild $TARGET_INITRD"
>                  return 1
>          fi
>
>  @@ -335,7 +336,12 @@ setup_initrd()
>                  # with fadump aware initrd
>                  backup_default_initrd
>          else
>  -               TARGET_INITRD="$KDUMP_INITRD"
>  +               if [ -z $TARGET_INITRD_DIR ]; then
>  +                       TARGET_INITRD="$KDUMP_INITRD"
>  +               else
>  +                       KDUMP_INITRD_BASE=$(basename "$KDUMP_INITRD")
>  +                      
> TARGET_INITRD="$TARGET_INITRD_DIR"/"$KDUMP_INITRD_BASE"
>  +               fi 
With this change, kdump on CoreOS still won't work out of box right?
User have to specify a TARGET_INITRD_DIR manually or it will fail.

I think put the initramfs image under /var/lib/kdump if /boot is not
writable should be a better idea, how do you think?



>                  # check if a backup of default initrd exists. If yes,
>                  # it signifies a switch from fadump mode. So, restore
>  --
>  2.29.2
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--
Best Regards,
Kairui Song

[Kelvin Fan]

Thanks for the suggestion, that sounds good to me!