The next commit will add a stage test that requires erofs-utils. Let's add it
into the buildroot in a separate commit, so the history is more readable.
Osbuild doesn't support creating btrfs over multiple devices, thus it should
be fine to have only single and dup in the schema (other options are for raid)
So we have a quick reference how to work with btrfs-based images.
Co-authored-by: Christian Kellner <christian@kellner.me>
Signed-off-by: Ondřej Budai <ondrej@budai.cz>
