autogenerated entries for other Ubuntu systems use wrong root filesystem, unbootable
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| grub2 (Ubuntu) |
Triaged
|
Medium
|
Unassigned | ||
Bug Description
On my disk I have two partitions that are root filesystems for two releases, Focal and Groovy:
Groovy 20.10 is on /dev/nvme0n1p3 3ac2446d-
Focal 20.04 is on /dev/nvme0n1p4 4ff7a630-
If I run update-grub2 from Groovy, it detects the Focal partition and generates this entry for it:
menuentry 'Ubuntu 20.04.1 LTS (20.04) (on /dev/nvme0n1p4)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_
insmod part_gpt
insmod ext2
if [ x$feature_
search --no-floppy --fs-uuid --set=root 4ff7a630-
else
search --no-floppy --fs-uuid --set=root 4ff7a630-
fi
linux /boot/vmlinuz-
initrd /boot/initrd.
}
Note how the menu correctly says it's on p4, and gives the right UUID there and in the search --fs-uuid lines, but then in the actual linux kernel line, it uses root=UUID=
If I try to boot from that menuentry, the boot fails. At one point I'm fairly sure saw a message about not being able to find its initrd flash by, but I wasn't able to capture that message. Eventually it gets to a single-user prompt, and at that point if I scroll back, here are the warnings (yellow) and errors (red) captured in the scrollback:
UNSUPP Starting of Executable File Format File System Automount Point not supported
FAILED Failed to mount /boot/efi
DEPEND Dependency failed for Local File Systems
If I give the root password and then type mount, it has /dev/nvme0n1p3 (the Groovy root) mounted on /, not p4 (the Focal root it should be using).
So if I want to be able to use that Focal partition, I can't use the entry generated by os-prober; I have to make my own entry and add it to somewhere like 40_custom (in reality, of course I want it earlier, before the nonworking os-prober entries, so I named it 25-local):
menuentry 'Ubuntu 20.04 Focal LTS on nvme0n1p4' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
if [ x$feature_
search --no-floppy --fs-uuid --set=root 4ff7a630-
else
search --no-floppy --fs-uuid --set=root 4ff7a630-
fi
linux /boot/vmlinuz-
initrd /boot/initrd.
}
ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: grub-common 2.04-1ubuntu35.1
ProcVersionSign
Uname: Linux 5.8.0-38-generic x86_64
ApportVersion: 2.20.11-0ubuntu50.3
Architecture: amd64
CasperMD5CheckR
Date: Thu Jan 21 10:26:38 2021
InstallationDate: Installed on 2020-04-29 (267 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: grub2
UpgradeStatus: Upgraded to groovy on 2020-10-23 (90 days ago)
mtime.conffile.
| Akkana Peck (akkzilla) wrote | #1 |
| Julian Andres Klode (juliank) wrote | #2 |
| Changed in grub2 (Ubuntu): | |
| importance: | Undecided → Low |
| status: | New → Triaged |
| Akkana Peck (akkzilla) wrote | #3 |
| Julian Andres Klode (juliank) wrote | #4 |
| Changed in grub2 (Ubuntu): | |
| importance: | Low → Medium |
Running two *Ubuntu installs on the same system is not really supported, as there can only be one grub installed.
Same for os-prober really, it doesn't really work correctly for anything other than Windows.
So I understand that there's an issue, and we can fix this, but the expectation is that os-prober will go away at some point, and you should not run two ubuntus on one system.
Though I guess you can override the grub distributor is environment variable to hack around things, making the second Ubuntu install as like ubuntu2 to the ESP, and then select that from the UEFI boot device menu.