diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
| commit | cf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch) | |
| tree | 757a3d280760c654767631cab5ad8af2d86d1848 /Documentation/rust/general-information.rst | |
| download | linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip | |
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij:
"Core changes:
- Use the non-blocking mux_state_try_select() in the generic MUX pin
control back-end
- Free pin maps on pinctrl_generic_to_map() failure in the core
helpers
New hardware pin control:
- Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC
(this is for the low power audio, LPASS = Low Power Audio SubSystem
portions)
- Upboard support on top of the Intel pin controller
- Apple T6030 and T6031 support (just compatible strings)
- Samsung Exynos 8855 SoC
- Mediatek MT6858 SoC
- Rockchip RK3308B and RV1106 SoCs
- Airoha EN7523 and AN7563 SoCs
Improvements:
- Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable
- Qualcomm improvements on top of the Qualcomm PDC (power domain
controller) irqchip improvements from tglx:s tree
- Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups
- The NPCM8xx driver has been put into shape fixing many pin and
group definitions
- Some non-urgent Tegra 264 pin assignments are fixed up
- Some non-urgent fixups to Airoha AN7581 and AN7583 registers and
pin assignments, missing features etc"
* tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits)
dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema
pinctrl: meson: sync some modify from A4
pinctrl: meson: a4: Add input enable pin configuration
pinctrl: realtek: rtd1625: remove unused group name spdif_sel
pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13
dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema
Revert "Merge branch 'ib-rsk7204' into devel"
pinctrl: rockchip: Add RV1106 pinctrl support
dt-bindings: pinctrl: rockchip: Add RV1106 compatible
pinctrl: rockchip: Decode drive strength in the get function
pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable
pinctrl: airoha: add support of an7563 SoC
dt-bindings: pinctrl: airoha: add support of an7563 pin controller
pinctrl: airoha: try to find chip scu node by phandle first
pinctrl: airoha: add support of en7523 SoC
dt-bindings: pinctrl: airoha: add support of en7523 pin controller
pinctrl: airoha: an7583: add support for olt pinmux
pinctrl: airoha: an7583: add support for pon_alt pinmux
pinctrl: airoha: an7583: add support for npu_uart pinmux
dt-bindings: pinctrl: airoha: an7583: add missed features
...
Diffstat (limited to 'Documentation/rust/general-information.rst')
| -rw-r--r-- | Documentation/rust/general-information.rst | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/Documentation/rust/general-information.rst b/Documentation/rust/general-information.rst new file mode 100644 index 000000000..09234bed2 --- /dev/null +++ b/Documentation/rust/general-information.rst @@ -0,0 +1,161 @@ +.. SPDX-License-Identifier: GPL-2.0 + +General Information +=================== + +This document contains useful information to know when working with +the Rust support in the kernel. + + +``no_std`` +---------- + +The Rust support in the kernel can link only `core <https://doc.rust-lang.org/core/>`_, +but not `std <https://doc.rust-lang.org/std/>`_. Crates for use in the +kernel must opt into this behavior using the ``#![no_std]`` attribute. + + +.. _rust_code_documentation: + +Code documentation +------------------ + +Rust kernel code is documented using ``rustdoc``, its built-in documentation +generator. + +The generated HTML docs include integrated search, linked items (e.g. types, +functions, constants), source code, etc. They may be read at: + + https://rust.docs.kernel.org + +For linux-next, please see: + + https://rust.docs.kernel.org/next/ + +There are also tags for each main release, e.g.: + + https://rust.docs.kernel.org/6.10/ + +The docs can also be easily generated and read locally. This is quite fast +(same order as compiling the code itself) and no special tools or environment +are needed. This has the added advantage that they will be tailored to +the particular kernel configuration used. To generate them, use the ``rustdoc`` +target with the same invocation used for compilation, e.g.:: + + make LLVM=1 rustdoc + +To read the docs locally in your web browser, run e.g.:: + + xdg-open Documentation/output/rust/rustdoc/kernel/index.html + +To learn about how to write the documentation, please see coding-guidelines.rst. + + +Extra lints +----------- + +While ``rustc`` is a very helpful compiler, some extra lints and analyses are +available via ``clippy``, a Rust linter. To enable it, pass ``CLIPPY=1`` to +the same invocation used for compilation, e.g.:: + + make LLVM=1 CLIPPY=1 + +Please note that Clippy may change code generation, thus it should not be +enabled while building a production kernel. + + +Abstractions vs. bindings +------------------------- + +Abstractions are Rust code wrapping kernel functionality from the C side. + +In order to use functions and types from the C side, bindings are created. +Bindings are the declarations for Rust of those functions and types from +the C side. + +For instance, one may write a ``Mutex`` abstraction in Rust which wraps +a ``struct mutex`` from the C side and calls its functions through the bindings. + +Abstractions are not available for all the kernel internal APIs and concepts, +but it is intended that coverage is expanded as time goes on. "Leaf" modules +(e.g. drivers) should not use the C bindings directly. Instead, subsystems +should provide as-safe-as-possible abstractions as needed. + +.. code-block:: + + rust/bindings/ + (rust/helpers/) + + include/ -----+ <-+ + | | + drivers/ rust/kernel/ +----------+ <-+ | + fs/ | bindgen | | + .../ +-------------------+ +----------+ --+ | + | Abstractions | | | + +---------+ | +------+ +------+ | +----------+ | | + | my_foo | -----> | | foo | | bar | | -------> | Bindings | <-+ | + | driver | Safe | | sub- | | sub- | | Unsafe | | | + +---------+ | |system| |system| | | bindings | <-----+ + | | +------+ +------+ | | crate | | + | | kernel crate | +----------+ | + | +-------------------+ | + | | + +------------------# FORBIDDEN #--------------------------------+ + +The main idea is to encapsulate all direct interaction with the kernel's C APIs +into carefully reviewed and documented abstractions. Then users of these +abstractions cannot introduce undefined behavior (UB) as long as: + +#. The abstractions are correct ("sound"). +#. Any ``unsafe`` blocks respect the safety contract necessary to call the + operations inside the block. Similarly, any ``unsafe impl``\ s respect the + safety contract necessary to implement the trait. + +Bindings +~~~~~~~~ + +By including a C header from ``include/`` into +``rust/bindings/bindings_helper.h``, the ``bindgen`` tool will auto-generate the +bindings for the included subsystem. After building, see the ``*_generated.rs`` +output files in the ``rust/bindings/`` directory. + +For parts of the C header that ``bindgen`` does not auto generate, e.g. C +``inline`` functions or non-trivial macros, it is acceptable to add a small +wrapper function to ``rust/helpers/`` to make it available for the Rust side as +well. + +Abstractions +~~~~~~~~~~~~ + +Abstractions are the layer between the bindings and the in-kernel users. They +are located in ``rust/kernel/`` and their role is to encapsulate the unsafe +access to the bindings into an as-safe-as-possible API that they expose to their +users. Users of the abstractions include things like drivers or file systems +written in Rust. + +Besides the safety aspect, the abstractions are supposed to be "ergonomic", in +the sense that they turn the C interfaces into "idiomatic" Rust code. Basic +examples are to turn the C resource acquisition and release into Rust +constructors and destructors or C integer error codes into Rust's ``Result``\ s. + + +Conditional compilation +----------------------- + +Rust code has access to conditional compilation based on the kernel +configuration: + +.. code-block:: rust + + #[cfg(CONFIG_X)] // Enabled (`y` or `m`) + #[cfg(CONFIG_X="y")] // Enabled as a built-in (`y`) + #[cfg(CONFIG_X="m")] // Enabled as a module (`m`) + #[cfg(not(CONFIG_X))] // Disabled + +For other predicates that Rust's ``cfg`` does not support, e.g. expressions with +numerical comparisons, one may define a new Kconfig symbol: + +.. code-block:: kconfig + + config RUSTC_HAS_SPAN_FILE + def_bool RUSTC_VERSION >= 108800 |
