On Thursday 23 June 2016 14:41:53, Mark Kettenis wrote: > We really don't want to implement bounce-buffers. Adding IOMMU > support is probably a better approach as it also brings some > security benefits. Not all amd64 hardware supports an IOMMU. And > hardware that does support it doesn't always have it enabled. But > for modern hardware an iommu is pretty much standard, except for > the absolute low-end. But those low-end machines tend to have only > 2GB of memory anyway.
On amd64, modern would mean skylake or newer. At least until haswell (not sure about broadwell), Intel considered vt-d to be a high-end feature and many desktop CPUs don't have it enabled. It is easy to find systems with >=16 GB RAM without IOMMU. Stefan
