When restoring the backup the rootfs is mounted in /rootfs/data
and the symlink to the real file would then not work. Attempt to
change the directory first to get a relative symlink.
Untested change and needed for rauc
We can not have sysmocom-backup-default and sysmocom-backup-data-default
installed at the same time. I don't want to play games with RREPLACE and
RPROVIDES either. So simply use one of the two files. Copy the two more
default values over to the other recipe.
With the ro image we have a cheap way to figure out which
files were changed. We can run cmp between the to be backed
up file. This way the stored data will be minimal in the
sense of changed files.
When using squashfs + overlayfs a root, we need to store the backup
somewhere else and restore it on every boot. Do avoid breaking existing
users, this is implemented in a separate recipe (as suggested by Holger).