It appears that btrfs root images built with ROOTFS_TYPE=btrfs are currently broken.  E.g., attempting to boot with a btrfs root:

 

Starting kernel ...

Loading, please wait...
starting version 232
Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Running /scripts/local-premount ... Scanning for Btrfs filesystems
done.
Begin: Will now check root file system ... fsck from util-linux 2.29.2
done.
mount: Invalid argument
done.
Begin: Running /scripts/local-bottom ... done.
Begin: Running /scripts/init-bottom ... mount: No such file or directory
mount: invalid option --
done.
mount: No such file or directory
run-init: current directory on the same filesystem as the root: error 0
Target filesystem doesn't have requested /sbin/init.
run-init: current directory on the same filesystem as the root: error 0
run-init: current directory on the same filesystem as the root: error 0
run-init: current directory on the same filesystem as the root: error 0
run-init: current directory on the same filesystem as the root: error 0
run-init: current directory on the same filesystem as the root: error 0
No init found. Try passing init= bootarg.
Rebooting automatically due to panic= boot argument
[   11.978967] reboot: Restarting system
INFO:    PSCI Affinity Map:

This happens with both BRANCH=next and BRANCH=dev builds (4.14 and 4.18).  ext4 roots work fine, of course.

 

Interestingly, if you boot an ext4 image on an SD card, and then use armbian-config to flash the image to eMMC using btrfs for the root filesystem, then the same boot problem occurs.  Something seems to have broken in terms of btrfs support in the initrd...  Any ideas?

 

6 hours ago, 5kft said:

Interestingly, if you boot an ext4 image on an SD card, and then use armbian-config to flash the image to eMMC using btrfs for the root filesystem, then the same boot problem occurs.  Something seems to have broken in terms of btrfs support in the initrd...  Any ideas?

I noticed and briefly checked. Perhaps here is the problem: https://github.com/armbian/build/pull/1069

10 hours ago, Igor said:

I noticed and briefly checked. Perhaps here is the problem: https://github.com/armbian/build/pull/1069

 

Yes, that change introduced the problem...  I just pushed a fix:  https://github.com/armbian/build/commit/c1530db4820320a1e837901196d846b0ef71ee4c