This bug was fixed in the package lowlatency-kernel - 1.3~25.04.1
---------------
lowlatency-kernel (1.3~25.04.1) plucky; urgency=medium
* Backport 1.3 from questing
- Skip update-grub if in a chroot (LP: #2119012)
-- Juerg Haefliger <juerg.haefli...@canonical.com> Tue, 29 Jul 2025
17:33:19 +0200
** Changed in: lowlatency-kernel (Ubuntu Plucky)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/2119012
Title:
Ubuntu Studio CD image build failure
Status in livecd-rootfs package in Ubuntu:
Confirmed
Status in lowlatency-kernel package in Ubuntu:
Fix Released
Status in livecd-rootfs source package in Noble:
Fix Released
Status in lowlatency-kernel source package in Noble:
Fix Released
Status in livecd-rootfs source package in Plucky:
Won't Fix
Status in lowlatency-kernel source package in Plucky:
Fix Released
Status in livecd-rootfs source package in Questing:
Confirmed
Status in lowlatency-kernel source package in Questing:
Fix Released
Bug description:
[ Impact ]
Ubuntu Studio uses the lowlatency kernel. With 6.14, the lowlatency
kernel is just the generic kernel with some bootargs to make it
lowlatency. This breaks the Ubuntu Studio livefs and CD image builds.
https://launchpad.net/~ubuntu-
cdimage/+livefs/ubuntu/noble/ubuntustudio
Problem 1)
The postinst hook of the lowlatency-kernel package calls update-grub
unconditionally which fails if the package is installed in a chroot.
From a livefs build log:
Processing triggers for dbus (1.14.10-4ubuntu4.1) ...
Processing triggers for libgtk-3-0t64:amd64 (3.24.41-4ubuntu1.3) ...
Processing triggers for shared-mime-info (2.4-4) ...
Processing triggers for libgtk2.0-0t64:amd64 (2.24.33-4ubuntu1.1) ...
Processing triggers for desktop-file-utils (0.27-2build1) ...
Processing triggers for initramfs-tools (0.142ubuntu25.5) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Processing triggers for libc-bin (2.39-0ubuntu8.5) ...
Processing triggers for man-db (2.12.0-4build2) ...
Processing triggers for dictionaries-common (1.29.7) ...
Processing triggers for linux-image-6.14.0-24-generic (6.14.0-24.24~24.04.3)
...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-6.14.0-24-generic
cryptsetup: ERROR: Couldn't resolve device overlay
cryptsetup: WARNING: Couldn't determine root device
cryptsetup: ERROR: Couldn't resolve device /dev/vdb
Errors were encountered while processing:
lowlatency-kernel
Problem 2)
The kernel flavor name changed from 'lowlatency' to 'generic'. This
breaks livecd-rootfs.
[2025-07-30 21:10:37] No catalog entry template for standard.live
[2025-07-30 21:10:38] P: Begin unmounting filesystems...
[2025-07-30 21:10:38] P: Saving caches...
[2025-07-30 21:10:38] No kernel output for lowlatency!
[2025-07-30 21:10:38] P: Begin unmounting filesystems...
[2025-07-30 21:10:38] P: Saving caches...
[2025-07-30 21:10:38] Build failed
Problem 3)
The ISO kernel is the generic kernel now so needs additional boot args
to make it lowlatency. Otherwise 'Try Ubuntu Studio' will run the
generic kernel which is likely not what we want.
[ Test Plan ]
1. Trigger an Ubuntu Studio livefs build and watch it succeed.
2. Boot a resulting CD image and verify the running kernel is lowlatency.
3. Install Ubuntu Studio and verify the running kernel is lowlatency.
[ Where Problems Could Occur ]
Other consumers of livecd-rootfs could fail, i.e., other livefs builds
might fail due to livecd-rootfs changes.
Machines that have the lowlatency-kernel package installed might not
update grub.cfg and hence not switch the kernel to lowlatency but
continue to run with generic settings.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/livecd-rootfs/+bug/2119012/+subscriptions
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