Update grub.texi to describe the external environment block in the
reserved area of Btrfs header used for grub-reboot and savedefault, and
add a section documenting the saved_entry, next_entry, and env_block
variables.
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Neal Gompa <ngompa13@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
6435551a66
