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Miller" , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, ttoukan.linux@gmail.com References: <20260813081410.5fdeceb1@kernel.org> <0444bbb8-39e2-40f8-b3c2-a5851e5bfa70@nvidia.com> <20260827081529.63513668@kernel.org> From: Gal Pressman Content-Language: en-US In-Reply-To: <20260827081529.63513668@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: FR3P281CA0149.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:95::20) To DM4PR12MB5248.namprd12.prod.outlook.com (2603:10b6:5:39c::15) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR12MB5248:EE_|IA1PR12MB8263:EE_ X-MS-Office365-Filtering-Correlation-Id: 9f68229b-919b-490c-d9e6-08df0805dd74 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|23010399003|376014|18002099003|22082099003|56012099006|3023799007|6133799003|4143699003|11063799006|10067099003|5023799004; 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We nacked multiple such drivers over the years. >>> Most recent one not more than a year ago. >>> >>> If you model the device as a network node it should be reachable via >>> the normal networking path. If it's a control channel - explicit >>> control channel APIs should be built, rather than doing pretend >>> networking. >>> >>> Every IPU vendor gets to this sort of design sooner or later because >>> it's an easy hack when running a user space SDK. nVidia has clearly >>> turned from upstream work to pushing your DOCA stack on all customers. >>> No matter how many shameful lies y'all told about fwctl not being DOCA >>> related. This is just a next step. But please commence your bullying >>> campaign. What do I know, right? >> >> There are some unrelated accusations here, I'll focus on the technical >> side of things. >> >> No DRAM NIC (NODNIC) is not a new interface designed for BlueField 4 or >> DOCA. It exists in our NIC since 2015, and implemented in other OSs >> drivers long before DOCA existed. >> >> It is a lightweight NIC PF intended for simple packet transmission with >> a small memory footprint. >> It sends and receives ordinary Ethernet frames using SQs, RQs, CQs, and >> EQs. There is no private encapsulation or command protocol. You can >> connect this PF to any other NIC on the other side of the wire and it >> will work. >> >> On BlueField 4, the firmware connects the host side NODNIC PF to a peer >> PF on the DPU side using ordinary vport forwarding rules. The Ethernet >> packets are forwarded unchanged, both sides are Linux netdevs. >> >> The purpose of this is to provide network connectivity between the host >> and the DPU OS, particularly when the DPU’s OOB port is not connected. >> Standard networking applications such as ssh and PXE use it. >> >> To be clear, there is no hidden FW involvement or handling of the >> packets, these packets are forwarded as is between both sides. >> It makes sense to use a networking driver for networking purposes, I >> don't see how control channel APIs are better for this. > > I understand. Having a full networking driver for such point to point > communication between device FW (/OS running on the device, doesn't > matter) complicates the system topology, config/init and mixes very > non-networking requirements with networking. It's a lazy design which > leads to poor, vendor-specific user experience. The NFP had a similar > thing, it obviously never made it upstream, but I'm very familiar with > the implications. What is the mix of non-networking requirements? >From the networking stack's perspective, this is pretty much the same as connecting the DPU's OOB port and communicating through that port's netdev. Also similar to how virtio-net has been used successfully between hypervisors and VMs for a long time. I can't comment on other companies' experience, but this driver is running successfully in our systems, we do not encounter the problems you described. What is the basis for the NACK? A technical problem with the networking driver itself, or a policy objection against this kind of DPU use case?