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charset=UTF-8 Date: Thu, 30 Jul 2026 23:50:06 +0900 Message-Id: Cc: "Eliot Courtney" , "Gary Guo" , "Danilo Krummrich" , "Alice Ryhl" , "Daniel Almeida" , "Miguel Ojeda" , "Boqun Feng" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Trevor Gross" , "Tamir Duberstein" , =?utf-8?q?Onur_=C3=96zkan?= , "David Airlie" , "Simona Vetter" , "Bjorn Helgaas" , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , , , , , , Subject: Re: [PATCH 01/10] rust: io: register: allow explicit base type specification From: "Alexandre Courbot" To: "John Hubbard" References: <20260721-typed_register-v1-0-452d72b60262@garyguo.net> <20260721-typed_register-v1-1-452d72b60262@garyguo.net> <4c82ae0a-d424-4aec-8423-3efdf95fbf63@nvidia.com> In-Reply-To: <4c82ae0a-d424-4aec-8423-3efdf95fbf63@nvidia.com> X-ClientProxiedBy: TYCP286CA0210.JPNP286.PROD.OUTLOOK.COM (2603:1096:400:385::19) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|DS7PR12MB6144:EE_ X-MS-Office365-Filtering-Correlation-Id: 37ec620e-8fd6-45ce-cbf8-08deee49daab X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|366016|10070799003|1800799024|23010399003|5023799004|56012099006|11063799006|4143699003|22082099003|18002099003|10067099003; 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The cost seems to be that yo= u >>> need to specify some region on every register, but afaict you could mak= e >>> that a Region the size of the entire BAR0 space, or a non-sized Region >>> and just have all your accesses fallible. So it's a bit noisy but otoh >>> it's nice to think about what space each of your registers exist in. >>=20 >> In the case of Nova that's something we might actually want to do: as >> their name suggest, registers are split in large blocks (PBUS, PFB, >> etc). And we are currently trying to move every register out of the > > Yes. The HW ref manuals have already set up an extensive taxonomy, and > it's probably a "feature-not-a-bug" to specify which region each access > is in, actually. > > For NVIDIA GPUs and other HW, that is. Note that if we switch to this model, the register offsets declared in Nova will be relative to their parent block - i.e. they won't match the offsets declared in OpenRM anymore. But that's probably not a problem since we can always look up the registers by name.