[9fans] how to combine 3ed and 4ed on one real fake worm fs?

[Axel Belinfante <Axel.Belinfante@cs.utwente.nl>]

I still have to make my first 4th ed installation,
but I'm looking ahead to how to 'upgrade' the fs,
(and not even thought about cpu/auth server) and
have the feeling I'm probably missing the obvious.

I understand the on-disk format is the same,
and the kernel speaks both 9P and 9P2000.

But, how do people convert their real (fake worm) fs?
(converted by booting the new kernel)
I mean: how/where to add the 4th ed files without mixing
them with the 3rd ed ones, such that root file systems
for both resp. 3rd ed and 4th ed are (can be) offered?
Somehow the effect should be something like Russ
described for the kfs filesystem, where the 3rd ed
files are moved to /3e
Or is the trick to add a new 'fresh' filsys for 4th ed?
(but that would waste the space already allocated for
 the 'current' main filsys).
Or just give up on 3th ed files? (I won't believe that :-)

Thanks,
Axel - who will now first try to install on a kfs-based
       Toshiba Tecra 8000 laptop