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    SubjectRe: [RFC PATCH 0/3] allow fallback to swiotlb on hw iommu init failures
    On Fri, 23 Oct 2009 23:57:12 -0700
    Chris Wright <> wrote:

    > > Note that Calgary comment 'falling back to no_iommu' is misleading. It
    > > actually falls back to swiotlb or nommu properly.
    > >
    > > Calgary doesn't set to dma_ops to calgary_dma_ops so it doesn't need
    > > to pick up swiotlb_dma_ops.
    > It does need swiotlb_dma_ops even when calgary init succeeds for the devices
    > that aren't behind Calgary to deal w/ the case of those devices having
    > dma mask smaller than physical memory (i.e those that don't get device
    > specific dma_ops set to calgary_dma_ops).

    I know since I wrote that code.

    > > > The calgary shouldn't even need to be manually setting up
    > > > nommu_dma_ops.
    > >
    > > Yeah, but it needs because of how the dma startup code works.
    > Be much better to have the core handle all of this. Basically register
    > ops and then put the top one on the stack to actual use. So the
    > fallback would be automatic, just pick the top of the stack and go.
    > Were you thinking of something along those lines?

    I don't know what 'register ops and then put the top one on the stack'
    means but it sounds overdoing.

    I think that we can handle this issue more simply. I've just posted
    the patchset.

     \ /
      Last update: 2009-10-28 07:57    [W:0.025 / U:47.640 seconds]
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