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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id k52sm13437898qtc.56.2020.09.22.09.52.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Sep 2020 09:52:10 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kKlWT-003CDZ-Jn; Tue, 22 Sep 2020 13:52:09 -0300 Date: Tue, 22 Sep 2020 13:52:09 -0300 From: Jason Gunthorpe To: Gal Pressman Cc: Oded Gabbay , Greg Kroah-Hartman , izur@habana.ai, Jakub Kicinski , "Linux-Kernel@Vger. Kernel. Org" , netdev@vger.kernel.org, SW_Drivers , "David S. Miller" , Andrew Lunn , Florian Fainelli , linux-rdma@vger.kernel.org, Olof Johansson Subject: Re: [PATCH v3 00/14] Adding GAUDI NIC code to habanalabs driver Message-ID: <20200922165209.GJ8409@ziepe.ca> References: <20200918141909.GU8409@ziepe.ca> <20200918150735.GV8409@ziepe.ca> <20200918152852.GW8409@ziepe.ca> <20200922114101.GE8409@ziepe.ca> <20200922161429.GI8409@ziepe.ca> 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-rdma@vger.kernel.org On Tue, Sep 22, 2020 at 07:30:32PM +0300, Gal Pressman wrote: > On 22/09/2020 19:14, Jason Gunthorpe wrote: > > On Tue, Sep 22, 2020 at 03:46:29PM +0300, Gal Pressman wrote: > > > >> I agree, that makes sense. > >> But assuming Oded actually goes and implements all the needed verbs to get a > >> basic functional libibverbs provider (assuming their HW can do it somehow), is > >> it really useful if no one is going to use it? > >> It doesn't sound like habanalabs want people to use GAUDI as an RDMA adapter, > >> and I'm assuming the only real world use case is going to be using the hl stack, > >> which means we're left with a lot of dead code that's not used/tested by anyone. > >> > >> Genuine question, wouldn't it be better if they only implement what's actually > >> going to be used and tested by their customers? > > > > The general standard for this 'accel' hardware, both in DRM and RDMA > > is to present an open source userspace. Companies are encouraged to > > use that as their main interface but I suppose are free to carry the > > cost of dual APIs, and the community's wrath if they want. > > I didn't mean they should maintain two interfaces. > The question is whether they should implement libibverbs support that covers the > cases used by their stack, or should they implement all "mandatory" verbs so > they could be able to run libibverbs' examples/perftest/pyverbs as well, even > though these will likely be the only apps covering these verbs. As I said, the minimum standard is an open source user space that will operate the NIC. For EFA we decided that was ibv_ud_pingpong, and now parts of pyverbs. A similar decision would be needed here too. It is a conversation that should start with a propsal from Oded. The *point* is to have the open userspace, so I really don't care what their proprietary universe does, and shrinking the opensource side becuase it is "redundant" is completely backwards to what we want to see. Jason