On Thursday 01 April 2010 02:09:09 am Avi Kivity wrote: > On 04/01/2010 03:08 AM, Tom Lyon wrote: > > uio_pci_generic has previously been discussed on the KVM list, but this > > patch has nothing to do with KVM, so it is also going to LKML. > > (needs to go to lkml even if it was for kvm) > > > 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. > > > > Specifically, I seek to allow low-latency user level network drivers (non > > tcp/ip) which directly access SR-IOV style virtual network adapters, for > > use with packages such as OpenMPI. > > > > Key areas of change: > > - ioctl extensions to allow registration and dma mapping of memory > > regions, with lock accounting > > - support for mmu notifier driven de-mapping > > Note that current iommus/devices don't support restart-on-fault dma, so > userspace drivers will have to lock memory so that it is not swapped > out. I don't think this prevents page migration, though. The driver provides a way to lock memory for DMA; the mmu notifier support is to catch things when the user accidentally frees locked pages. > > - support for MSI and MSI-X interrupts (the intel 82599 VFs support only > > MSI-X) > > How does a userspace program receive those interrupts? Same as other UIO drivers - by read()ing an event counter. -- 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
