[PATCH] powerpc/8xx: fix regression introduced by cache coherency rewrite

[Benjamin Herrenschmidt]

> hmm, yes. You do get this and mysterious SEGV if you hit the but so does
> other bugs too so this is probably due to missing invalidation.
> 
> I suspect that something like below will fix the problem and
> is the "correct" fix(untested, not even compiled):

Ok but do we also still have to worry about the "unpopulated" TLB
entries and invalidate them somehow when populating ?

Cheers,
Ben.