On Fri, Jul 31, 2020 at 01:15:34PM -0400, Steven Sistare wrote: > On 7/31/2020 12:56 PM, Jason Gunthorpe wrote: > > On Fri, Jul 31, 2020 at 12:11:52PM -0400, Steven Sistare wrote: > >>> Your preservation-across-exec use-case might or might not need the > >>> VMA to be mapped at the same address. > >> > >> It does. qemu registers memory with vfio which remembers the va's in kernel > >> metadata for the device. > > > > Once the memory is registered with vfio the VA doesn't matter, vfio > > will keep the iommu pointing at the same physical pages no matter > > where they are mapped. > > Yes, but there are other code paths that compute and use offsets between va and the > base va. Mapping at a different va in the new process breaks vfio; I have tried it. Maybe you could fix vfio instead of having this adventure, if vfio is the only motivation. Jason
