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[47.55.113.94]) by smtp.gmail.com with ESMTPSA id y15sm10797034qto.90.2021.06.21.07.17.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Jun 2021 07:17:57 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1lvKkO-009WjS-US; Mon, 21 Jun 2021 11:17:56 -0300 Date: Mon, 21 Jun 2021 11:17:56 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: Oded Gabbay , Christoph Hellwig , linux-rdma , "open list:DMA BUFFER SHARING FRAMEWORK" , Doug Ledford , "airlied@gmail.com" , Linux Kernel Mailing List , Greg KH , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Gal Pressman , sleybo@amazon.com, dri-devel , Tomer Tayar , "moderated list:DMA BUFFER SHARING FRAMEWORK" , amd-gfx list , Alex Deucher , Leon Romanovsky Subject: Re: [PATCH v3 1/2] habanalabs: define uAPI to export FD for DMA-BUF Message-ID: <20210621141756.GF1096940@ziepe.ca> References: <20210618123615.11456-1-ogabbay@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 21, 2021 at 02:28:48PM +0200, Daniel Vetter wrote: > Mission acomplished, we've gone full circle, and the totally-not-a-gpu > driver is now trying to use gpu infrastructure. And seems to have > gained vram meanwhile too. Next up is going to be synchronization > using dma_fence so you can pass buffers back&forth without stalls > among drivers. Well, we can't even see the other side of this so who knows This is a new uAPI, where is the userspace? In RDMA at least I require to see the new userspace and test suite before changes to include/uapi/rdma can go ahead. > Doug/Jason from infiniband: Should we add linux-rdma to the dma-buf > wildcard match so that you can catch these next time around too? At > least when people use scripts/get_maintainers.pl correctly. All the > other subsystems using dma-buf are on there already (dri-devel, > linux-media and linaro-mm-sig for android/arm embedded stuff). My bigger concern is this doesn't seem to be implementing PCI P2P DMA correctly. This is following the same hacky NULL page approach that Christoph Hellwig already NAK'd for AMD. This should not be allowed to proliferate. I would be much happier seeing this be done using the approach of Logan's series here: https://lore.kernel.org/linux-block/20210513223203.5542-1-logang@deltatee.com/ Jason