On Fri, May 08, 2015 at 04:46:17PM -0400, Mark Hounschell wrote: > On 05/08/2015 04:21 PM, Konrad Rzeszutek Wilk wrote: > >On Fri, May 01, 2015 at 01:32:12PM -0500, wdavis@xxxxxxxxxx wrote: > >>From: Will Davis <wdavis@xxxxxxxxxx> > >> > >>Hi, > >> > >>This patch series adds DMA APIs to map and unmap a struct resource to and from > >>a PCI device's IOVA domain, and implements the AMD, Intel, and nommu versions > >>of these interfaces. > >> > >>This solves a long-standing problem with the existing DMA-remapping interfaces, > >>which require that a struct page be given for the region to be mapped into a > >>device's IOVA domain. This requirement cannot support peer device BAR ranges, > >>for which no struct pages exist. > >> > >>The underlying implementations of map_page and map_sg convert the struct page > >>into its physical address anyway, so we just need a way to route the physical > >>address of the BAR region to these implementations. The new interfaces do this > >>by taking the struct resource describing a device's BAR region, from which the > >>physical address is derived. > >> > >>The Intel and nommu versions have been verified on a dual Intel Xeon E5405 > >>workstation. I'm in the process of obtaining hardware to test the AMD version > >>as well. Please review. > > > >Does it work if you boot with 'iommu=soft swiotlb=force' which will mandate > >an strict usage of the DMA API? > > > > PCIe peer2peer is borked on all motherboards I've tried. Only writes are :-( > possible. Reads are not supported. I suppose if you have a platform with > only PCI and an IOMMU this would be very useful. Without both read and write > PCIe peer2peer support, this seems unnecessary. > It is a perfect way to test the code to make sure the API works (or it fails in the failure modes) _and_ that the drivers as well (use the pci_map_sync, and so on). > Mark > > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
