Subject: m88k pmap
To: None <port-m88k@netbsd.org>
From: Allen Briggs <briggs@ninthwonder.com>
List: port-m88k
Date: 07/10/2000 13:10:45
I'm starting to look at the pmap module for m88k (starting with what
Tohru has).  I spent a little bit of time looking at the M88110
documentation.  It looks like the page table descriptors are compatible.
The BATC and PATC are not, but I don't think we should be manipulating
those by hand anyway.  One fairly large difference is in the cache
flushing.  I don't see how the 88200 and 88110 can share any code here,
so it would make sense to have two different modules for TBIA() and
friends and call through function pointers to the appropriate code
instead of littering #ifdefs and/or doing "switch (cputype)" types
of constructions.

Back on pmap.c, does anyone know if the interface has changed
significantly since the 4.4 interface?  I don't recall any changes,
but I also notice that there is no documentation in section 9 of the
man pages (I think there should be, and I will write some if no one
beats me to it).

It looks (from what little I've poked at it so far) like the pmap
could be similar to the m68k format.  The page tables are in a 2-level
format that's similar to the 68030 & 68851 (w/ 4K pages).

Pax,
-allen