Subject: Re: status of the G4 l2 cache flush and MSR errate patch

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 13 Jan 2005 01:33:05 +0100

> 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 <[email-masked]>
> > ## 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.

Ben.