Bug#1117563: systemd: /usr/lib/kernel/install.d/55-initrd.install ignores existing initrds

[Nick Rosbrook]

On Tue, Oct 7, 2025 at 5:25 PM Benjamin Drung <bdrung at ubuntu.com> wrote:
>
> Package: systemd
> Version: 258-1
> Severity: normal
> X-Debbugs-Cc: bdrung at debian.org
>
> Dear Maintainer,
>
> The Dracut 12-uefi and 43-kernel-install test cases fail. dracut-core
> ships /usr/lib/kernel/install.d/50-dracut.install which generates an
> initrd in KERNEL_INSTALL_STAGING_AREA.
> /usr/lib/kernel/install.d/55-initrd.install (coming from
> debian/extra/kernel-install.d/55-initrd.install) then links to the
> initrd in /boot. This results in two initrd being included in the UKI
> and the content of later one overwrites the former one.
>
> Please modify debian/extra/kernel-install.d/55-initrd.install to check
> for the presence of an initrd in KERNEL_INSTALL_STAGING_AREA before
> linking to the initrd in /boot.
>

I wonder if it would be better to try and standardize around
$KERNEL_INSTALL_INITRD_GENERATOR[1].

I see that dracut configures this in tests by setting
`initrd_generator=dracut`[2] in e.g. /etc/kernel/install.conf. But,
dracut-core does not actually ship a kernel/install.conf.d drop-in on
real systems.

Also, dracut-core's 50-dracut.install has:

if [[ "${KERNEL_INSTALL_INITRD_GENERATOR:-dracut}" = "dracut" ]]; then
    # We are the initrd generator
    IMAGE="initrd"
    UEFI_OPTS="--no-uefi"
else
    exit 0
fi

which means it continues if $KERNEL_INSTALL_INITRD_GENERATOR is
"dracut" OR unset.

So, I think the following would be a cleaner approach:

(a) dracut-core ships /usr/lib/kernel/install.conf.d/50-dracut.conf
with at least `initrd_generator=dracut` to declare itself as the
initrd generator.
(b) dracut-core's 50-dracut.install is a no-op when
$KERNEL_INSTALL_INITRD_GENERATOR != "dracut".
(c) systemd's 55-initrd.install is a no-op unless
$KERNEL_INSTALL_INITRD_GENERATOR is unset.

What do you think?

-Nick

[1] https://www.freedesktop.org/software/systemd/man/latest/kernel-install.html
[2] https://codesearch.debian.net/search?q=initrd_generator%3D+package%3A%5CQdracut%5CE&literal=1