On Thu, Jun 06, 2019 at 09:59:35AM -0300, Jason Gunthorpe wrote: > > Until we've sorted that out the device paramter needs to be set to > > the smallest value supported. > > smallest? largest? We've been setting it to the largest value the > device can handle (ie 2G) Well, in general we need the smallest value supported by any ULP, because if any ULP can't support a larger segment size, we must not allow the IOMMU to merge it to that size. That being said I can't really see why any RDMA ULP should limit the size given how the MRs work.