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Re: MPC8260 cache patch


Gary Thomas wrote:
On Fri, 2003-03-28 at 07:20, Patrick Doyle wrote:

OK, I'll try to put it together over the weekend and send out a patch
Monday.

Just as a sanity check, do you think that removing the 'INVALIDATE()' calls
from the 'HAL_FLASH_CACHES_OFF()' macro is still worth doing?  I think it
should be safe (note the big difference between "I think" and "I have proved
conclusively" here).  Or do you think we should leave them in?


Yes, I also think that it's safe in this case.

I vaguely recall something about some architecture or variant (not powerpc) which had caches where, if you "just" disabled them, it would still use the cache lines that were still valid. So the invalidate was needed too. Perhaps Nick might remember the specifics? Although I also vaguely recall it was one of Jesper's ports.


FWIW, re the rest of the discussion and a view from afar, dedicating 16K permanently out of RAM would be bad, and doing out of some specific region where it matters less would be painful to get portable. Given the frequency of a SYNC, I think Patrick's patch is reasonable. Perhaps Patrick could add an explanatory comment next to the macro as to why it's 2* as well.

Jifl
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