Messages in this thread | | | Date | Wed, 25 Nov 2009 08:57:43 +0900 | Subject | Re: [PATCH] x86: fix gart iommu using for amd 64 bit system | From | FUJITA Tomonori <> |
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On Tue, 24 Nov 2009 16:26:45 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> > * FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote: > > > > don't think user will like to use SWIOTLB instead of swiotlb. > > > > I doubt that users care about a way to fix their problems. > > As far as swiotlb vs. GART goes, arguably a non-bouncing hw based > solution (GART) is superior to a bouncing one (swiotlb), right?
Yeah, but GART is not a real IOMMU that always does address translation. If users want performance, they need 64bit DMA capable devices to skip GART. With such devices, GART and SWIOTLB are same.
So this hacky GART workaround is useful for only people who use non 64bit DMA devices and broken BIOS with GART. IMO, it's not worth having the workaround.
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