Re: [PATCH 9/9] x86: Detect whether we should use Xen SWIOTLB.

From: Konrad Rzeszutek Wilk
Date: Mon Aug 02 2010 - 12:44:31 EST


On Tue, Aug 03, 2010 at 01:01:08AM +0900, FUJITA Tomonori wrote:
> On Mon, 02 Aug 2010 08:47:53 -0700
> "H. Peter Anvin" <hpa@xxxxxxxxx> wrote:
>
> > On 08/02/2010 08:43 AM, FUJITA Tomonori wrote:
> > >
> > > That's the difficult part because IOMMUs are not
> > > interdependent. Hardware IOMMUs are related with swiotlb. GART and
> > > AMD-IOMMU are too.
> > >
> > > We could invent sorta IOMMU register interface and driver-ize IOMMUs
> > > but they can't be interdependent completely.
> >
> > Of course. However, we need there to be as much structure to it as
> > there can be.
>
> Ok, let's see if Konrad can invent something clean.

<chuckles> Thank you for your vote of confidence.
>
> But his attempt to create "swiotlb iommu function array" and "hardware
> iommu function array" looks like to makes the code more unreadable.

Let me go to my favorite coffee shop and think this one through.
Can I get concession for putting the original patch in (the simple, dumb one),
and then:
- start working on the IOMMU register interface without having to try
to get it done for 2.6.36, and
- do the driverization as a seperate cleanup.

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