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. 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? -Mark Langsdorf AMD, Inc. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
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. > > 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?This is long overdue. Thanks for starting the work. Muli and I have been peripherally looking at this, but have not done any work on it yet. Please keep us in the loop, and let us know if you need any help :) Thanks, Jon> > -Mark Langsdorf > AMD, Inc. > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Muli Ben-Yehuda
2006-May-07 12:19 UTC
Re: [Xen-devel] Using arch/x86_64/pci-dma in x86_64 Xen
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? Cheers, Muli _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Christian Limpach
2006-May-07 19:45 UTC
Re: [Xen-devel] Using arch/x86_64/pci-dma in x86_64 Xen
On 5/7/06, Muli Ben-Yehuda <muli@il.ibm.com> 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 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Langsdorf, Mark
2006-May-08 13:31 UTC
RE: [Xen-devel] Using arch/x86_64/pci-dma in x86_64 Xen
> > > 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? > > 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.I don''t think there''s enough differences between the bare metal dma ops and the Xen dma ops to justify a common implementation. Also, the common implementation implies that each IOMMU interface needs to have some knowledge of the other interfaces, and I don''t think that''s sustainable long term. -Mark Langsdorf AMD, Inc. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel