Arch Linux

Hi, i have been digging around that problem all the day, thinking it was grub's problem, it was not. Os-Prober on Arch and Debian base seem to fail to detect other Linux on a BTRFS filesystem to add them to the grub menu. I tried first to simply chainload the other Linux's own grub on it own partition (MBR Legacy) and it worked. So from there, i looked which distros had a working one from the report i had from friend, surprisingly, Manjaro had not that problem.

My test bench was a KVM Virtual Machine, 1 virtual hdd, sda1 being Mint in BTRFS and arch in sda2. If mint was in ext4, arch would detect it, if mint's in BTRFS, it fail to see it. Made a snapshoot, replaced arch with manjaro, it detect Mint. Don't matter if arch use BTRFS or ext4 or if Manjaro's BTRFS or ext4. Digging a bit, i replaced grub of arch by the one from manjaro, it was not the problem and made it waste my time compiling. Replace arch's os-prober with manjaro's os-prober, it worked. Update arch's grub to the legit one from arch, it still detect it. So at this point, i look at manjaro and arch's os-prober, same version. So seem Manjaro did some tweak to Os-Prober to make it working.

The good news, the tweak are on their gitlab, here's the source and difference for the Os-Prober. https://gitlab.manjaro.org/packages/community/os-prober/commit/fca491a96e627c1d626b2d74c931726fcb5e3951

The problem's even weirder since it also make on some system i installed to make grub not detect Windows 10. So, it's not just BTRFS but NTFS and probably a couple other FileSystem. Manjaro's OS-Prober was updated in July while arch got an update for it in august but show the same version id.

Here's an example of using arch's os-prober, replacing it with manjaro's os-prober and having better result.