[Bug 1993066] Re: 10_linux_zfs produces incorrect grub.cfg when a zfs backup of another encrypted Zsys install exists

[Heinrich Schuchardt]

The logic for detecting pools is in /etc/grub.d/10_linux_zfs.

In the defective state could you, please, provide the output of
executing the following statements.

zpool list

zpool get -H altroot <pool>  # for each pool

Please, indicate which pool corresponds to the backup and which one you
expected to appear in the GRUB menu.

** Changed in: grub2 (Ubuntu)
       Status: New => Incomplete

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Title:
  10_linux_zfs produces incorrect grub.cfg when a zfs backup of another
  encrypted Zsys install exists

Status in grub2 package in Ubuntu:
  Incomplete

Bug description:
  10_linux_zfs produces incorrect grub.cfg when a zfs backup of another
  encrypted Zsys install exists.

  I backed up my other Ubuntu PC via zfs send/recv a snapshot of rpool,
  which was stored on another zpool on my main PC. As a ZFS backup, it
  contained the complete structure of a Zsys install.

  Subsequently, update-grub produced a grub.cfg with no entries.

  After destroying the backup, update-grub produced normal results with
  kernels being properly detected.

  Versions:

  Up-to-date Ubuntu 22.04.1
  grub-common:
    Installed: 2.06-2ubuntu7

  Output when running update-grub with the backup residing on another zpool:
  /etc/kernel/postinst.d/zz-update-grub:
  Sourcing file `/etc/default/grub'
  Sourcing file `/etc/default/grub.d/init-select.cfg'
  Sourcing file `/etc/default/grub.d/kdump-tools.cfg'
  Generating grub configuration file ...
  zfs_mount_at() failed: encryption key not loadedMemtest86+ needs a 16-bit boot, that is not available on EFI, exiting
  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

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