24.04 grub-pc fails on dpkg-reconfigure

[Vladyslav Riabyk]

Hello!

I am trying to provision a baremetall node using ubuntu24.04 and use curtin to configure it. I have a well tested configuration file which was used with curtin-21.3 and ubuntu20.04. However it doesn't work when I try it on ubuntu24.04. It fails on dpkg-reconfigure grub-pc step. There is software raid 1 configured and lvm root volume on it, here is curtin configuration file:

```
storage:
  version: 1
  config:
     - id: system_disk0
       type: disk
       ptable: msdos
       model: KXG60ZNV256G TOSHIBA
       serial: 31RY10AQYRU1
       grub_device: 1
       wipe: superblock
     - id: system_disk0_part_1
       type: partition
       offset: 4194304B
       size: 256056320000B
       device: system_disk0
       flag: bios_grub
       wipe: superblock
     - id: system_disk1
       type: disk
       ptable: msdos
       model: KXG60ZNV256G TOSHIBA
       serial: 31RY10AVYRU1
       grub_device: 1
       wipe: superblock
     - id: system_disk1_part_1
       type: partition
       offset: 4194304B
       size: 256056320000B
       device: system_disk1
       flag: bios_grub
       wipe: superblock
     - id: mddevice
       name: md0
       type: raid
       raidlevel: 1
       devices:
         - system_disk0_part_1
         - system_disk1_part_1
     - id: lvm_volume_group
       type: lvm_volgroup
       name: system
       devices:
       - mddevice
     - id: lvm_logical_volume_root
       type: lvm_partition
       name: lv_root
       volgroup: lvm_volume_group
     - id: lvm_root_format
       type: format
       fstype: ext4
       volume: lvm_logical_volume_root
     - id: lvm_root_mount
       type: mount
       path: /
       device: lvm_root_format
```

So it configures successfully raid and lvm volumes. But then fails on dpkg-reconfigure grub-pc (see attached log file).

The problem can be reproduced manually, so I can mount, chroot and then run:
```
$ debconf-show grub-pc
  grub-pc/mixed_legacy_and_grub2: true
  grub-pc/install_devices_failed: false
  grub-pc/install_devices_disks_changed:
  grub2/kfreebsd_cmdline_default: quiet splash
  grub2/update_nvram: true
  grub-pc/timeout: 0
  grub2/linux_cmdline:
* grub-efi/cloud_style_installation: true
  grub2/linux_cmdline_default: quiet splash
  grub-efi/install_devices_failed: false
  grub-pc/kopt_extracted: false
  grub2/unsigned_kernels_title:
  grub-pc/disk_description:
  grub2/unsigned_kernels:
  grub-efi/install_devices_empty: false
  grub-pc/chainload_from_menu.lst: true
  grub2/no_efi_extra_removable: false
* grub-pc/install_devices: /dev/disk/by-id/nvme-eui.00000000000000018ce38e01000a4355, /dev/disk/by-id/nvme-eui.00000000000000018ce38e01000a435b
  grub-pc/postrm_purge_boot_grub: false
  grub-efi/install_devices:
  grub-pc/partition_description:
  grub2/kfreebsd_cmdline:
* install_devices:
  grub-pc/install_devices_failed_upgrade: true
  grub-efi/install_devices_disks_changed:
  grub-pc/hidden_timeout: true
* grub-pc/install_devices_empty: false
  grub-efi/partition_description:
* grub-pc/cloud_style_installation: true
  grub2/enable_os_prober: false

$ dpkg-reconfigure grub-pc
Installing for i386-pc platform.
File descriptor 3 (pipe:[263483]) leaked on vgs invocation. Parent PID 55120: grub-install
File descriptor 3 (pipe:[263483]) leaked on vgs invocation. Parent PID 55120: grub-install
File descriptor 3 (pipe:[263483]) leaked on vgs invocation. Parent PID 55120: grub-install
File descriptor 3 (pipe:[263483]) leaked on vgs invocation. Parent PID 55120: grub-install

File descriptor 3 (pipe:[263483]) leaked on vgs invocation. Parent PID 55120: grub-install
grub-install: warning: File system `ext2' doesn't support embedding.
grub-install: warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged..
grub-install: error: will not proceed with blocklists.
```

install_devices looks correct and symlinks point to real nvme6n1 and nvme7n1 devices (not partitions). If I set `cloud_style_installation: false` - dpkg-reconfigure passes without errors, but it seems then grub doesn't trigger installation actually.

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Bug reporting is about finding & fixing problems thus preventing future users from hitting the same bug.

I suspect a Support site would be more appropriate, eg. https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709

Please execute the following command only once, as it will automatically gather debugging information, in a terminal:

apport-collect 2076329

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.