Enabling peer to peer device transactions for PCIe devices

[Jason Gunthorpe]

On Thu, Jan 12, 2017 at 10:11:29AM -0500, Jerome Glisse wrote:
> On Wed, Jan 11, 2017 at 10:54:39PM -0600, Stephen Bates wrote:
> > > What we want is for RDMA, O_DIRECT, etc to just work with special VMAs
> > > (ie. at least those backed with ZONE_DEVICE memory). Then
> > > GPU/NVME/DAX/whatever drivers can just hand these VMAs to userspace
> > > (using whatever interface is most appropriate) and userspace can do what
> > > it pleases with them. This makes _so_ much sense and actually largely
> > > already works today (as demonstrated by iopmem).

> So i say let solve the IOMMU issue first and let everyone use it in their
> own way with their device. I do not think we can share much more than
> that.

Solve it for the easy ZONE_DIRECT/etc case then.

Jason