Re: C3 support w/o ARB_DIS (P4-M on i845)

[Dominik Brodowski <linux-X3ehHDuj6sIIGcDfoQAp7BvVK+yQ3ZXh@public.gmane.org>]

On Wed, May 12, 2004 at 12:25:27PM +0200, Karol Kozimor wrote:
> So, it seems there is some C3 support, but it is not used due to lack of
> bus-mastering control (PM2_CNT_BLK is 0). However, the flags section in the
> FADT indicates that WBINVD is supported. The comment in processor.c says
> the possibility of using C3 in the absence of ARB_DIS must be investigated.
> What is the current status? Any obvious caveats for implementation?

Well, there had been some discussion about that approximately two years ago,
maybe it's still in the archives. Major problems, IIRC:

a) occasional hangs on my system
b) unpredictable time of execution of WBINVD command (results in high latency)

I had posted some implementation back then, don't know whether it still
works. If you can't find it, contact me again, please.

	Dominik


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