Re: [Xen-devel] Using arch/x86_64/pci-dma in x86_64 Xen

["Christian Limpach" <christian.limpach@xxxxxxxxx>]

On 5/7/06, Muli Ben-Yehuda <muli@xxxxxxxxxx> wrote:
> On Thu, May 04, 2006 at 09:57:35AM -0500, Langsdorf, Mark wrote:
>
> > The current implementation of pci-dma in x86_64 Xen
> > Linux is to use the i386 implementation.  I don't
> > believe this is sustainable in the long term, as
> > x86_64 Xen is going to need more DMA solutions than
> > just SWIOTLB and plain hardware as various IOMMU
> > implementations arrive.
>
> 100% agreed.
>
> > The mainstream kernel has a clean abstraction layer
> > with the dma_ops that should be portable to Xen dom0
> > and domU.  I've started implementing this in a
> > pci-dma-xen for x86_64 Xen Linux.  Am I stepping on
> > anyone's toes or is there anyone I should be
> > co-ordinating this with?
>
> Please keep Jon and me in the loop, we added the dma_ops to the main
> kernel for the Calgary IOMMU but haven't got around to porting the
> various Xen dma ops to it.
>
> Also, I believe Christian had some thoughts about the direction going
> forward for the Xen specific dma ops?
I think that using the dma_ops abstraction layer on x86_64 is
definitely the way to go.  It's just not clear how the Xen specific
dma ops should be implemented in the end, whether having a common
implementation is worthwhile considering that it will require glue
code to make it fit with the different interfaces.

    christian

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