This is an old revision of the document!
BTRFS
as root filesystem
create root subvolume
mount /dev/sda1 /tmp/btrfs btrfs subvolume set-default 5 /tmp/btrfs cd /tmp/btrfs btrfs subvolume create @
add “ rootflags=subvol=@ ” to grub kernel options
if update-grub fail check http://edoceo.com/notabene/grub-probe-error-cannot-find-device-for-root this