On Mon, 16 Oct 2017 16:56:21 +0800 Yang Zhong <yang.zh...@intel.com> wrote:
> Qemu does not need pin NVDIMM memory for VFIO device during VFIO > hotplug, what's more, if there is no NVDIMM hw in the test machine, > the VFIO hotplug operation will need at least 10 minutes to pin RAM > as the NVDIMM, this time is not accepted. So we add "nopin=on" option > in the memory-backed-file, which can avoid to pin RAM memory for NVDIMM. > > The new command like below: > -object > memory-backend-file,id=mem0,share,nopin=on,mem-path=kvm.img,size=9161408512 > > The default of "nopin" still "off" value, which is same with previous value. If an NVDIMM is not a possible DMA target for a VFIO assigned device then it should be in a different AddressSpace from the device. If an NVDIMM can be a DMA target then it's the correct thing to do to pin it through the IOMMU for a VFIO device even if it might take considerable time to do so. Thanks, Alex
