Caches on MPC8260-like CPUs

Leon Pollak leonp at plris.com
Wed Oct 8 21:09:34 UTC 2008


On Wednesday, 8 בOctober 2008, Thomas Doerfler wrote:
> Leon,
>
> the MPC5200 and the MPC83xx are also based on a 603le core (which is
> only slightly different). We use the caches there properly. What aspects
> are you interested in?
>
> wkr,
> Thomas.
Thank you Thomas.

I have a general question.

In MPC860 I had a lot of different ways to fill TLBs so, that I had 1:1 
virtual memory mapping and still was able to define rather good separation 
between different cache strategies for my RAM. This was provided by the 
ability to define rather large pages in TLBs (up to 256MB).
Thus, I never had the page miss interrupt.


The MPC8260 TLBs have pages fixed to 4KB, as I was able to understand. And 
there is 64 of them. This means that I need to use the page miss interrupt to 
redefine the TLB with still the same 1:1 memory mapping?

I do not understand something here....


I thought to use BATs, but there is only 8 of them, which seems to be a bit 
tight...

Thank again.
-- 
Leon



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