Public bug reported:
Ubuntu Version:
Description: Ubuntu 20.04.2 LTS
Release: 20.04
Package Version:
os-prober:
Installed: 1.74ubuntu2
Candidate: 1.74ubuntu2
Version table:
*** 1.74ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages
100 /var/lib/dpkg/status
Given the following setup:
Given a configuration with boot partition on non bios raid drive, and Another
OS with its own boot partition (such as Windows) on bios raid drive. User is
desiring to chainload the other os from grub.
What should happen:
OS Prober detects Other OS's boot partition (such as windows) and forward the
correct EFI file to grub during configuration. Grub now knows about the other
OS and will show up in menu to be chainloaded.
What happens:
os-prober skips the mounted boot partition on the bios raid device because it
gets caught by the "Is this a virtual device" check on line 32 of
/usr/lib/os-probes/mounted/05efi. Grub is not configured for the other OS with
a boot partition on bios raid. Grub doesn't know about the other os requiring
manual configuration to add EFI files to grub.
Summary:
Due to the restrictive conditional in /usr/lib/os-probes/mounted/05efi line 32
any mdraid device such as an intel soft raid are not processed by os-prober for
other OS's that support boot partitions on bios raid (such as windows). This
means in dual boot scenarios where grub is not installed on the bios raid but
is used to chainload an os on the bios raid, the Other OS won't be detected or
present without manual configuration. As mdadm has supported assembling most
bios raids for some time and is loadable as a grub module, os-prober should
support probing for other OS's in this situation. While this is an edge case,
it is a very easy to believe to be supported edge case and should require
minimal modification to fix as intel bios raids have an easily grep-able
identifier in the udevadm info output. As far as I can tell mdadm will always
use the container 'MD_CONTAINER=/dev/md/imsm*' where star is the identifier
number (eg. 0) which should be easily detectable and allow detection of it as a
"regular" drive and not virtual. I've attached a patch for another easy way it
can be done by just grepping for /dev/md*p* that could allow for different
types of raids but potentially have other draw backs on very edge case setups.
** Affects: os-prober (Ubuntu)
Importance: Undecided
Status: New
** Patch added: "potential fix for allowing os-prober to detect other os's on
bios raid drives loaded by mdadm."
https://bugs.launchpad.net/bugs/1926925/+attachment/5494324/+files/os_prober_01_imsm_raid_fix.diff
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https://bugs.launchpad.net/bugs/1926925
Title:
os-prober doesn't detect EFI boot partitions on mdraid devices in dual
boot
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