From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Subject: Re: Enabling peer to peer device transactions for PCIe devices
Date: Thu, 12 Jan 2017 10:17:20 -0700
Message-ID: <20170112171720.GA12257@obsidianresearch.com>
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To: Jerome Glisse <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: david1.zhou-5C7GfCeVMHo@public.gmane.org, "'linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org'" <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "'linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org'" <linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org>, "Kuehling,
 Felix" <felix.kuehling-5C7GfCeVMHo@public.gmane.org>, Serguei Sagalovitch <serguei.sagalovitch-5C7GfCeVMHo@public.gmane.org>, "Blinzer,
 Paul" <paul.blinzer-5C7GfCeVMHo@public.gmane.org>, "'linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org'" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "'dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org'" <dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, qiang.yu-5C7GfCeVMHo@public.gmane.org, "Sander, Ben" <ben.sander-5C7GfCeVMHo@public.gmane.org>, "Suthikulpanit, Suravee" <suravee.suthikulpanit-5C7GfCeVMHo@public.gmane.org>, "'linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org'" <linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "Deucher,
 Alexander" <alexander.deucher-5C7GfCeVMHo@public.gmane.org>, Jerome Glisse <j.glisse-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, "Koenig, Christian" <christian.koenig-5C7GfCeVMHo@public.gmane.org>, "'Linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org'" <linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
List-Id: dri-devel@lists.freedesktop.org

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