status of the G4 l2 cache flush and MSR errate patch

Benjamin Herrenschmidt benh at
Thu Jan 13 11:33:05 EST 2005

> Mmm, well, i am not really the author of this one. Jacob Pan from freescale is
> the author, so we should change this, will do. So this should show :
> ## DP: Patch author: Pan Jacob-r7aahq <Jacob.Pan at>
> > ## DP: Upstream status: under review by benh.
> The patch does two things. Use hardware assist for cache flush, which seems to
> be ok on 744x processors, but broken on earlier G4s and G3s. And add a printk
> in case of some exception, so the user knows about it instead of it being
> silently discarded. 

The HW assist isn't completely ok neither... it should be enough for
enabling the cache at boot though. I've been banging my head lately
trying to get a properly working & reliable cache flush mecanism for use
on the Mac laptops since we need that for cpufreq and sleep on various
models, but what I have right now is just a "works most of the time"
kind of implementation.

> I was under the impression that benh said that the patch was ok, but not
> really relevant, since it applies to code travel cases which either are not
> really used in the common case, or result in a dying of the kernel anyway.
> Don't remember all the details though. They do respond to some G4 processor
> errata's though.

I'll have a look again. Just back from vacation, leave me a coupe of
days to catch up with everything and I'll take care of those.


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