On 08/10/2018 09:24 AM, Logan Gunthorpe wrote: > > > On 10/08/18 10:02 AM, Kit Chow wrote: >> Turns out there is no dma_map_resource routine on x86. get_dma_ops >> returns intel_dma_ops which has map_resource pointing to NULL. > > Oh, yup. I wasn't aware of that. From a cursory view, it looks like it > shouldn't be too hard to implement though. > >> Will poke around some in the intel_map_page code but can you actually >> get a valid struct page for a pci bar address (dma_map_single calls >> virt_to_page)? If not, does a map_resource routine that can properly >> map a pci bar address need to be implemented? > > Yes, you can not get a struct page for a PCI bar address unless it's > mapped with ZONE_DEVICE like in my p2p work. So that would explain why > dma_map_single() didn't work. > > This all implies that ntb_transport doesn't work with DMA and the IOMMU > turned on. I'm not sure I've ever tried that configuration myself but it > is a bit surprising. Hmm....that's surprising because it seems to work on Skylake platform when I tested it yesterday with Intel NTB. Kit is using a Haswell platform at the moment I think. Although I'm curious if it works with the PLX NTB he's using on Skylake. > > Logan >
