[Buildroot] btrfs filesystem image as subvolume

[Gervais, Francois]

Hi,

I tried the btrfs filesystem image and it works fine however in my
use-case I'd like to have only the subvolume and not the whole btrfs
filesystem.

Basically the output of "btrfs send".

I'd first like to make sure this is not possible today and discuss some
high level guidelines you would like me to follow when I implement
the feature.

Should I add a sub-option to the "btrfs root filesystem" menu?
Should if have it's own "Filesystem images" entry?

Thank you