la 19.4.2025 klo 8.43 Felix Zielcke (fziel...@z-51.de) kirjoitti: > > Am Freitag, dem 18.04.2025 um 21:17 +0300 schrieb Martin-Éric Racine: > > Hey Felix, > > > > pe 18.4.2025 klo 19.39 Felix Zielcke (fziel...@z-51.de) kirjoitti: > > > > > > Am Freitag, dem 18.04.2025 um 19:10 +0300 schrieb Martin-Éric > > > Racine: > > > > The Debian changelog suggests what caused this: > > > > > > > > Someone enabled compiling GRUB with FUSE3 to enhance QEMU > > > > support. > > > > The problem with FUSE3 is that it only has very basic support for > > > > btrfs, lacking among other things support for subvolumes. This is > > > > a > > > > serious issue considering how widely spread btrfs has become and > > > > how > > > > debian-installer uses subvolumes by default whenever someone > > > > selects > > > > brtfs as the filesystem type. Rendering hosts unbootable is a big > > > > no-no. I would really hope the release team to step in on this > > > > one. > > > > > FUSE support in GRUB 2 is only used for the grub-mount binary. And > > > not > > > at all in the actual booting code loaded from EFI/BIOS. > > > > > > You could though test the fs drivers of it with grub-mount: > > > > > > grub-mount /dev/sda2 /mnt (replace sda2 with your / partition) > > > sha1sum /mnt/@rootfs/boot/initrd.img-6.12.20-amd64 > > > sha1sum /@rootfs/boot/initrd.img-6.12.20-amd64 > > > > > > both commands should output the same hash sum. > > > And yes, this is safe with a mounted fs because the GRUB fs code is > > > 100% complete read-only.
Same checksum. However, manually executing this tells us nothing. It's performed on a filesystem that's already available. It doesn't simulate GRUB attempting to cold mount a system on a booting host. > > Exactly how does the above address the issue I reported? > > Well, then we at least know that the bug is not in GRUB's btrfs > filesystem code > So your initramfs should be correctly read by it There seems to be two issues here: 1) A magic error upon loading initrd. It also affects the Trixie rescue mode via UEFI (but not via BIOS). Bookworm rescue mode boots both ways. 2) fuseblk reporting an unsupported subvol option on Trixie. It's a simply a/b test: Downgrading grub* to Bookworm made the host bootable again. Martin-Éric
