Grub 2.12~rc1-4ubuntu2 with ZFS will not list any boot entries

[Danilo Egea Gondolfo]

After upgrading to the new grub the boot menu only contains the memtest86 entries.

It can be easily reproduced by installing the system with ZFS (either plain ZFS or with encryption) using the latest desktop legacy image https://cdimage.ubuntu.com/daily-legacy/current/. After installation the system will boot straight into memtest86 (because that's the only thing in the menu).

For people facing the same issue, you can boot your system manually from grub with this:

set root=(hd0,gptX)
linux /BOOT/ubuntu_nedhsb/@/vmlinuz root=ZFS=rpool/ROOT/ubuntu_nedhsb boot=zfs
initrd /BOOT/ubuntu_nedhsb/@/initrd.img
boot

[Danilo Egea Gondolfo (danilogondolfo)]

Here is what I get from update-grub2:

$ sudo update-grub2

Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
/etc/grub.d/10_linux_zfs: 229: version_sort_sort_has_v: parameter not set
Warning: didn't find any valid initrd or kernel.
Found memtest86+ 64bit EFI image: /BOOT/ubuntu_nedhsb@/memtest86+x64.efi
Warning: os-prober will not be executed to detect other bootable partitions.
Systems on them will not be added to the GRUB boot configuration.
Check GRUB_DISABLE_OS_PROBER documentation entry.
Adding boot menu entry for UEFI Firmware Settings ...
done

[Danilo Egea Gondolfo (danilogondolfo)]

Is version_sort_sort_has_v missing initialization somewhere? https://git.launchpad.net/ubuntu/+source/grub2/tree/util/grub-mkconfig_lib.in?id=06f86533332124471075e20d139ceb97ce7a655b#n205

I initialized it to "yes" before calling the function version_sort and it generated the list.

[Danilo Egea Gondolfo (danilogondolfo)]

Ok, the problem is this set -u here https://git.launchpad.net/ubuntu/+source/grub2/tree/debian/patches/ubuntu-zfs-enhance-support.patch?id=06f86533332124471075e20d139ceb97ce7a655b#n95

It will error out when an undefined variable is found.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub2 - 2.12~rc1-4ubuntu3

---------------
grub2 (2.12~rc1-4ubuntu3) mantic; urgency=medium

  * zfs: Drop `set -u`, incompatible with undefined variables in library
    (LP: #2033256)

 -- Julian Andres Klode <email address hidden> Tue, 29 Aug 2023 16:03:49 +0200