From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma Date: Wed, 30 Jan 2019 18:26:53 +0100 Message-ID: <20190130172653.GA6707@lst.de> References: <20190129174728.6430-1-jglisse@redhat.com> <20190129174728.6430-4-jglisse@redhat.com> <20190129191120.GE3176@redhat.com> <20190129193250.GK10108@mellanox.com> <99c228c6-ef96-7594-cb43-78931966c75d@deltatee.com> <20190129205827.GM10108@mellanox.com> <20190130080208.GC29665@lst.de> <4e0637ba-0d7c-66a5-d3de-bc1e7dc7c0ef@amd.com> <20190130155543.GC3177@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190130155543.GC3177@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Jerome Glisse Cc: "Koenig, Christian" , Christoph Hellwig , Jason Gunthorpe , Logan Gunthorpe , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Greg Kroah-Hartman , "Rafael J . Wysocki" , Bjorn Helgaas , "Kuehling, Felix" , "linux-pci@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Marek Szyprowski , Robin Murphy , Joerg Roedel , "iommu@lists.linux-foundation.org" List-Id: iommu@lists.linux-foundation.org On Wed, Jan 30, 2019 at 10:55:43AM -0500, Jerome Glisse wrote: > Even outside GPU driver, device driver like RDMA just want to share their > doorbell to other device and they do not want to see those doorbell page > use in direct I/O or anything similar AFAICT. At least Mellanox HCA support and inline data feature where you can copy data directly into the BAR. For something like a usrspace NVMe target it might be very useful to do direct I/O straight into the BAR for that.