Comment 2 for bug 2028702

Switching the boot partition from zfs to ext4 makes the whole thing boot again.

The source of the problem could be found afterwards: as grub command zfsinfo indicated: there where zfs features enabled grub zfs could not handle -- the kernel with zfs enabled indeed could. grub found bpool, but was not able to access it.

To help others out:
- enable grub to handle these zfs features or
- switch booting of an ext4 2G partition.

switching is easy, because swap has the same size than the bpool-partition.

1. boot into your not booting linux as adviced.
2. turn of swap, disable it in /etc/fstab
3. format the swap-partition to ext4, mount it to say /BB
4. unmount /boot/grub, /boot/efi
5. copy all files from /boot to /BB
6. add your new ext4 partition to /etc/fstab
7. export zfs bpool: zpool export bpool
8. mount your new ext4 using fstab: mount /boot
9. mount /boot/efi
10. mount /boot/grub
11. grub-install /dev/sda
    This has to run without any error!
12. update-grub
    This too has to run without errors.
13. unmount all drives mounted from chroot. /boot/grub, /boot/efi, /boot
14. exit chroot
15. format the bpool-partition to swap
    -> this will partly fail, because zfs keeps track on it. But mostly zfs-informations are destroyed.
16. reboot
    -> system reboots, but without swap
17. format dwap again (just to be sure it is ok.
18. edit /etc/fstab to reflect the new UUID for swap
19. enable swap.
20. reboot

Now there is no bpool anymore and grub goots from a 2GiB ext4 partition into zfs.