Re: OpenBlockS600 (AMCC 405EX) again

[Rafal Jaworowski <raj%semihalf.com@localhost>]

On 2010-03-11, at 20:01, Simon Burge wrote:

>> I'm adding support for the Freescale BookE e500 chips in powerpc/booke.
>> Not sure if the 440s are closer to the 405 or the e500.
> 
> Different enough that at the previous employer the e500 core had yet
> another pmap :-/   I only touched those ports rarely, so I'll not be
> much help saying why it needed a different pmap again.

There's a number of fundamental differences (MMU, exceptions model): for 
example, E500 (and Book-E in general) cannot turn off the MMU, so there always 
need to be valid TLB translations present.

We have a dedicated pmap in FreeBSD as well for the Book-E, because it's very 
much like a different architecture than the traditional PowerPC. PPC405 seems 
somewhere between Book-E and the traditional PowerPC definition.

Rafal