Packaging multiple filesystems

[zestrada]

We encounter firmware images with multiple filesystems quite often. Some rehostings require that we place those filesystems at correct mount points. The current approach in those situations is to do a bunch of manual static analysis to determine the potential mount points for and then stitch together relevant partitions into one rootfs that is consumed by penguin init.

Some initial work on automatically handling this in fw2tar has been done in rehosting/fw2tar#20 and it works reasonably well for cases it has been tested on.

Some thoughts from discussion with @AndrewFasano :

• What about an approach of refactoring penguin init to support a directory of partitions?
  • We can then handle filesystem unification stuff in penugin and manage with the config, and then possibly do searches over various options if there isn't a clear winner

[zestrada]

Some more design thoughts about how to figure out where and how to make changes; looking at penguin changes soon