Arch Linux

0bitpixel

Member

Registered: 2025-12-02

Posts: 2

[SOLVED] Thought Btrfs was missing from kernel – false alarm

Root cause for issue was missing block-hook from mkinitcpio, preventing Btrfs from booting.
Solved by simply adding `block` to HOOKS list.

Btrfs is built into the kernel, and thus, the missing module directory is expected.

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ORIGINAL POST

BTRFS code missing in kernels linux-6.17.9 and linux-zen-6.17.9

Latest kernel versions are *entirely* missing BTRFS code.

I noticed after updating kernels and recreating initramfs, my system with a BTRFS-root-drive would no longer boot.

As far as I am aware, this is a catastrophic packaging mistake and should be fixed ASAP.

Steps to reproduce:

# pacman -Sy linux linux-headers linux-zen linux-zen-headers

Expected:
- BTRFS Code files in

/lib/modules/6.17.9-arch1-1/build/fs/btrfs

and

/lib/modules/6.17.9-zen1-1-zen/build/fs/btrfs

Actual:

$ find /lib/modules/6.17.9-arch1-1/ -name "btrfs"
/lib/modules/6.17.9-arch1-1/build/fs/btrfs

$ ls -la /lib/modules/6.17.9-arch1-1/build/fs/btrfs
insgesamt 4
drwxr-xr-x 1 root root   14  2. Dez 12:36 .
drwxr-xr-x 1 root root  702  2. Dez 12:36 ..
-rw-r--r-- 1 root root 4071 24. Nov 16:21 Kconfig


$ find /lib/modules/6.17.9-zen1-1-zen/ -name "btrfs"
/lib/modules/6.17.9-zen1-1-zen/build/fs/btrfs

$ ls -la /lib/modules/6.17.9-zen1-1-zen/build/fs/btrfs
insgesamt 4
drwxr-xr-x 1 root root   14  2. Dez 12:36 .
drwxr-xr-x 1 root root  702  2. Dez 12:36 ..
-rw-r--r-- 1 root root 4071 24. Nov 16:21 Kconfig

Last edited by 0bitpixel (2025-12-02 13:10:01)

gromit

Administrator

From: Germany

Registered: 2024-02-10

Posts: 1,404

Website

Re: [SOLVED] Thought Btrfs was missing from kernel – false alarm

BTRFS has not been a module for 8 months now and it is built into the kernel, so the problem that you're facing has to be a different one:
https://gitlab.archlinux.org/archlinux/ … 5a8e4f8047

Please post the actual error that you're seeing before mistakingly jumping to any conclusion ..

0bitpixel

Member

Registered: 2025-12-02

Posts: 2

Re: [SOLVED] Thought Btrfs was missing from kernel – false alarm

Alright, issue solved. My mistake: Turns out Btrfs has been built into the kernel for months, so the missing module directory is expected.

My actual boot failure was caused by mkinitcpio missing the block-hook required on Btrfs-boots.
LTS booted fine because the initramfs still had it.
Re-adding the block-hook fixed everything.

Marking post as [SOLVED] and softening title for less panic.