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Sat, 4 Apr 2026 10:02:35 +0000 Date: Sat, 4 Apr 2026 12:02:28 +0200 From: Maciej Fijalkowski To: Jakub Kicinski CC: , , , , , , , , Subject: Re: [PATCH v6 net 4/8] xsk: validate MTU against usable frame size on bind Message-ID: References: <20260402154958.562179-1-maciej.fijalkowski@intel.com> <20260402154958.562179-5-maciej.fijalkowski@intel.com> <20260403170357.14cb166a@kernel.org> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260403170357.14cb166a@kernel.org> X-ClientProxiedBy: VI1PR0902CA0028.eurprd09.prod.outlook.com (2603:10a6:802:1::17) To DM4PR11MB6117.namprd11.prod.outlook.com (2603:10b6:8:b3::19) 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: DM4PR11MB6117:EE_|DS4PPF900531A26:EE_ X-MS-Office365-Filtering-Correlation-Id: 43b6acb8-2697-41c6-8882-08de92314b8a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024|18002099003|56012099003|22082099003; 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Furthermore, validate whether underlying HW will > > be able to satisfy configured MTU wrt XSK's frame size multiplied by > > supported Rx buffer chain length (that is exposed via > > net_device::xdp_zc_max_segs). > > For multi-buf - I suppose it's fine, but wouldn't this be potentially > a regression for setups which use single buf? Suddenly we expect the > user to provide space for shinfo which was not part of the initial > AF_XDP design? For single buf xsk_pool_get_tailroom() gives you 0 so it is not taken into account when we do comparison of mtu vs xsk frame size (in this case frame size is defined as chunk size minus headrooms (xdp and user provided one)).