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Re: when and how to enable caches



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Hello,

On May 25, 2008, at 05:20, Frank Wille wrote:

Tim Rightnour wrote:

locore is entered with caches disabled, MMU disabled, BATs and SRs
invalidated. MSR has only the IP-bit set.

Anybody remembers a similar problem? Any idea what I could check or try?

What kind of CPU is that exactly?

A 233MHz 604e. No L2-cache present.


some of the CPU's have a very specific
set of operations you have to perform in a very specific order to turn
caches on and off. Its usually documented in one of the CPU manuals.

I'm reading the 604 User's Manual, but I didn't find examples for such a
sequence.

BTW, I tried the same sequence to enable/invalidate caches on my Efika (5200B),
which has caches already enabled in OF, and it crashed too!

Hmm, I have a kinda-sorta similar problem on ohare-based Macs with external L2 cache - if I enable it too late the machine goes bananas and ofb's cache trickery deadlocks it ( which is one of the motivations for switching to genfb )

have fun
Michael

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