I just installed Xubuntu alongside an Arch-based distro. The problem is that Grub2 does not detect the (btrfs) partition of the previous distro, so I can't boot from it. I have already tried update-grub2.
By the way, that btrfs partition used to boot alright from Grub2, before I installed Xubuntu.
What can I do?
Best Answer
The GRUB os-prober has problems detecting btrfs @subvolumes, the easiest answer from "rick3332" from ubuntu-forums made it work for me on both dual-boot btrfs based OS installs(ubuntu16&18) each with their own grub. There is no need for comprehensive hack os-prober code or do non-persistent manual grub.cfg edits. Just create symlinks in each btrfs volume roots for @/boot and @/etc and run "sudo update-grub2" afterwards in each OS.
https://ubuntuforums.org/showthread.php?t=2369106&p=13677811#post13677811