Unexpected end of file for kernel 6.15

[Aragorn]

@megavolt

@Aragorn

This is a known problem with kernel 6.15 and grub when /boot is on btrfs.

Interestingly, I’m running linux 6.15 and have been using cat for compression for months as I’m already compressing that via BTRFS file system. I have not encountered this problem. Maybe @Aragorn’s solution will help.

EDIT: I tried switching from cat to zstd and rebooted. No problem at all. I don’t think there’s a problem buried here.

It’s not a problem until you rebuild the initramfs. Switching back to zstd without rebuilding the initramfs won’t make a difference.

There is however a problem with 6.15 on btrfs — see this thread, and it’s a grub problem.

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@linux-aarhus

So the issue comes from the fact that using btrfs on /boot creates a read error when decompressing a compressed file stored on a compressed filesystem?

Yes, exactly. btrfs uses inline compression, and in combination with an additional external compression algorithm, this may lead to the creation of sparse files. grub cannot handle those, because it does not have proper support for btrfs.

As has also already been noted elsewhere, grub will also not save the last-booted entry if /boot is on btrfs because grub cannot write to btrfs, and as we’ve just seen again, it also has problems reading from it under certain circumstances.