Messages in this thread | | | Date | Tue, 3 Aug 2010 00:43:52 +0900 | Subject | Re: [PATCH 9/9] x86: Detect whether we should use Xen SWIOTLB. | From | FUJITA Tomonori <> |
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On Mon, 02 Aug 2010 08:30:38 -0700 "H. Peter Anvin" <hpa@zytor.com> wrote:
> On 08/02/2010 08:25 AM, Konrad Rzeszutek Wilk wrote: > > hpa, are your concerns that a) inserting a sub-system call in the > > generic code is not good. Or b) that we have five IOMMUs (counting SWIOTLB in that > > category) and that we don't jettison from memory the ones we don't need > > (that would be the primary goal of driverization of those IOMMUs, > > right?). Or c) we should remove all sub-system detect calls (Calgary, AMD, > > Intel, AGP) altogether from pci-dma.c and depend more on > > x86_init.iommu structure (perhaps expend it?) > > Sorry, had to deal with other stuff. > > Basically, a) and c) are the issues, with a) being the more immediate; > the amount of code left in memory is relatively small and as such I'm > not too concerned with that aspect specifically. > > With five IOMMUs we're well past the point where we need to have a clean > and generic interface instead of having everything be ad hoc and > interdependent.
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.
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