On Wed, Jan 15, 2025 at 09:55:29AM +0100, Simona Vetter wrote: > I think for 90% of exporters pfn would fit, but there's some really funny > ones where you cannot get a cpu pfn by design. So we need to keep the > pfn-less interfaces around. But ideally for the pfn-capable exporters we'd > have helpers/common code that just implements all the other interfaces. There is no way to have dma address without a PFN in Linux right now. How would you generate them? That implies you have an IOMMU that can generate IOVAs for something that doesn't have a physical address at all. Or do you mean some that don't have pages associated with them, and thus have pfn_valid fail on them? They still have a PFN, just not one that is valid to use in most of the Linux MM.