Re: [PATCH] x86: create array based interface to change page attribute

Andi Kleen
2008-03-31T08:34:46Z

> Also I think we need to clarify the semantics of the c_p_a
> functionality. Right now both AGP and DRM relies on c_p_a doing an
> explicit cache flush. Otherwise the data won't appear on the device side
> of the aperture.

But surely not in cpa I hope ? Or are you saying you first write data
and then do cpa? If true that would be quite an abuse of CPA
I would say and you should fix it ASAP.

> If we use self-snoop, the AGP and DRM drivers can't rely on this flush
> being performed, and they have to do the flush themselves, and for

They definitely should flush themselves if they want data to reach
the device. That is obviously required any time they reuse a page
too.

-Andi