On Tue, Jan 09, 2018 at 05:46:40PM +0100, Christoph Hellwig wrote:

On Mon, Jan 08, 2018 at 12:49:50PM -0700, Jason Gunthorpe wrote:

quoted

Pretty sure P2P capable IOMMU hardware exists.

With SOC's we also have the scenario that an DMA originated from an
on-die device wishes to target an off-die PCI BAR (through the IOMMU),
that definitely exists today, and people care about it :)

Then people will have to help and contribute support for it.

Sure. But my point was all this will have to migrate under the dma_ops
for that to work, so why the resistance to using dma_ops right away?

Jason