On Thu, Apr 01, 2010 at 08:40:34AM -0700, Tom Lyon wrote: > On Thursday 01 April 2010 05:52:18 am Joerg Roedel wrote: > > > The point of this patch is to beef up the uio_pci_generic driver so that > > > a non-privileged user process can run a user level driver for most PCIe > > > devices. This can only be safe if there is an IOMMU in the system with > > > per-device domains. Privileged users (CAP_SYS_RAWIO) are allowed if > > > there is no IOMMU. > > > > If you rely on an IOMMU you can use the IOMMU-API instead of the DMA-API > > for dma mappings. This change makes this driver suitable for KVM use > > too. If the interface is designed clever enough we can even use it for > > IOMMU emulation for pass-through devices. > The use with privileged processes and no IOMMUs is still quite useful, so I'd > rather stick with the DMA interface. For the KVM use-case we need to be able to specify the io virtual address for a given process virtual address. This is not possible with the dma-api interface. So if we want to have uio-dma without an hardware iommu we need two distinct interfaces for userspace to cover all use-cases. I don't think its worth it to have two interfaces. Joerg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
