Partition sizing

[Demi Marie Obenour <demiobenour@gmail.com>]

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What size should the A and B partitions be?  I can’t think of
any reasonable way to size them that is also future-proof.

Android had the same problem, and they solved it by using
device mapper.  Unfortunately, I doubt LVM meets our security
goals, which means a whole new userspace implementation would
be required.  That would not be fun, especially since a bug
would require a reinstall to correct.

Other image-based Linux distros generally don't have this
problem because they use filesystem or ostree snapshots,
rather than separate partitions.  Chromium OS has a whole
team of paid developers, so I think they can deal with
constraints a bit better than we can :).

One horrifying worst-case option is to add a file on the
user data partition, create a loop device based on it,
and then add it to the dm-verity table.  I really don't
want to do that if there is any other option, though.
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

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