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Wysocki" , "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?= , "Bjorn Helgaas" , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , "Abdiel Janulgue" , "Robin Murphy" , "David Airlie" , "Simona Vetter" , "Michal Wilczynski" , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , "Danilo Krummrich" , , , , , , , Subject: Re: [PATCH v5 16/20] rust: io: add `read_val` and `write_val` functions on `Io` From: "Alexandre Courbot" To: "Gary Guo" References: <20260626-io_projection-v5-0-d0961471ae50@garyguo.net> <20260626-io_projection-v5-16-d0961471ae50@garyguo.net> In-Reply-To: <20260626-io_projection-v5-16-d0961471ae50@garyguo.net> X-ClientProxiedBy: OS3P286CA0117.JPNP286.PROD.OUTLOOK.COM (2603:1096:604:1f7::6) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|CYXPR12MB9279:EE_ X-MS-Office365-Filtering-Correlation-Id: 62e2fb27-8278-49e6-68c1-08ded9117b86 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|10070799003|7416014|376014|23010399003|366016|11063799006|4143699003|5023799004|3023799007|18002099003|22082099003|56012099006; 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which is typically only implemented for > atomically accessible primitives. `dma_read!` and `dma_write!` currently > supports them via `read_volatile` and `write_volatile`; this can be > undesirable for aggregates as LLVM may turn them to multiple instructions > to access parts and re-assemble, even if they could be combined to a sing= le > instruction. Thus, `io_read!()` and `io_write!()` does not fully replace > `dma_read!()` and `dma_write!()` in this scenario. The ability to > read/write aggregates (when atomicity is of no concern) is better served > with copying primitives (e.g. memcpy_{from,to}io). > > Signed-off-by: Gary Guo Reviewed-by: Alexandre Courbot <...> > @@ -1225,3 +1269,63 @@ macro_rules! io_project { > } > #[doc(inline)] > pub use crate::io_project; > + > +/// Read from I/O memory. > +/// > +/// The syntax is of form `io_read!(io, proj)` where `io` is an expressi= on to a type that > +/// implements [`Io`] and `proj` is a [projection specification](kernel:= :ptr::project!). > +/// > +/// # Examples > +/// > +/// ``` > +/// struct MyStruct { field: u32, } Same as patch 13, maybe this should be `#[repr(C)]` to give the good example to readers. (same for the other example below)