[Bug 1838525] Re: LVM setup fails to install grub on virtio storage

[Rafael David Tinoco]

Thanks a lot for those 2 files, I compared side by side and it called my
attention:

https://pastebin.ubuntu.com/p/VJXrJHsqRB/

this difference:

+ partmap /dev/vda1                          | + partmap /dev/sda
Error: /dev/vda1: unrecognised disk label    < 

Which Im currently investigating (and why it picked /dev/vda1 instead of
/dev/vda like it should). That, likely, triggered the logic to keep
select_bootdev as "/dev/mapper":

+ log 'debug: select_bootdev: arg='"'"'/dev/mapper'"'"    | + log
'debug: select_bootdev: arg='"''"

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https://bugs.launchpad.net/bugs/1838525

Title:
  LVM setup fails to install grub on virtio storage

Status in debian-installer package in Ubuntu:
  New
Status in grub-installer package in Ubuntu:
  Triaged
Status in debian-installer source package in Eoan:
  New
Status in grub-installer source package in Eoan:
  Triaged
Status in debian-installer package in Debian:
  New

Bug description:
  The Eoan debian-installer ISO fails to install GRUB on LVM installs
  with virtio storage, as it runs grub-install with /dev/mapper as a
  target (a directory), even if instructed to target a device.

  The following steps to reproduce have been prepared running the
  20190730 build, but this has been broken since about June 18, 2019.
  Steps to reproduce:

  $ md5sum eoan-server-amd64.iso
  f591e30485e5f0b5117f6c116e538c42  eoan-server-amd64.iso
  $ qemu-img create -f raw disk1.img 8G
  Formatting 'disk1.img', fmt=raw size=8589934592
  $ kvm -m 1024 -boot d -cdrom eoan-server-amd64.iso -drive file=disk1.img,if=virtio

  Proceed with all the defaults. In the "Partition disk" step select
  "Guided - use entire disk and set up LVM". Go ahead accepting the
  defaults. At the "Install the GRUB boot loader" step select "/dev/vda"
  as the target device. The installer will actually run `grub-install
  --force /dev/mapper` and fail after a while. The wrong command is
  visible both in the d-i screen and by running `ps` on a different
  console.

  Full installer syslog: http://paste.ubuntu.com/p/qtZy86dTp6/

  It's interesting how this doesn't happen when not using virtio. If
  from the commands above the "if=virtio" option is dropped then
  everything works as expected. In this case the target block device is
  called /dev/sda instead of /dev/vda.

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