Messages in this thread | | | Date | Tue, 16 Sep 2008 22:20:40 +0900 | Subject | Re: [PATCH 0/3] fix GART to respect device's dma_mask about virtual mappings | From | FUJITA Tomonori <> |
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On Tue, 16 Sep 2008 02:54:32 +0200 Andi Kleen <andi@firstfloor.org> wrote:
> FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> writes: > > > Currently, gart IOMMU ignores device's dma_mask when it does virtual > > mappings. So it could give a device a virtual address that the device > > can't access to. > > Huh? That is what the need_iommu() logic in gart_map_sg() > does. An I'm not aware of any bugs in this area.
What the need_iommu() does is seeing if GART needs to do virtual mappings or not.
(After need_iommu() checking) What this patchset does is to guarantee that GART provides a virtual address that a device can access to.
> Did you actually see that failure in practice? I don't see > how it could happen.
No, I did not. This patchset does the right thing theoretically, I think, but if such problem never happens for GART, I'll drop the patch for GART. Joerg?
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