Re: rtVAX300 .. adding an CPU Type..

[Jason Thorpe <thorpej%shagadelic.org@localhost>]

On Jan 4, 2013, at 2:39 AM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:

>>> As some of you already know I'm fiddeling around with an ISA Board
>>> in a PC that has an rtVAX 300 CPU on it.
> 
>> The primary difference between the rtVAX and normal VAX is that the rtVAX re$
> 
> It's not totally clear to me, yet, whether the rtVAX 300 works this way
> or whether it has the normal VAX P0 and P1 setup.  The ROM code makes
> me moderately sure that either it's a normal VAX in this respect or it
> ignores the high bit of the P0BR - all ROM code that sets P0BR sets the
> high bit except for one case which I suspect is an expected-to-fail
> test.
> 
>> This means all the process page tables have to be physically contiguous (as $
> 
> Perhaps proper KA620 (and other machines with that style of P0/P1 page
> tables) support would mean building a pmap that migrates pages in an
> attempt to maintain a large physically contiguous free block?

...or uses a single page table and zeroes / lazy-copies from process-specific 
tables as needed.  (OMG that would be so slow... but easy :-)

-- thorpej