80 lines
2.5 KiB
ReStructuredText
80 lines
2.5 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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General Information
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===================
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This document contains useful information to know when working with
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the Rust support in the kernel.
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Code documentation
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------------------
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Rust kernel code is documented using ``rustdoc``, its built-in documentation
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generator.
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The generated HTML docs include integrated search, linked items (e.g. types,
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functions, constants), source code, etc. They may be read at (TODO: link when
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in mainline and generated alongside the rest of the documentation):
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http://kernel.org/
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The docs can also be easily generated and read locally. This is quite fast
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(same order as compiling the code itself) and no special tools or environment
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are needed. This has the added advantage that they will be tailored to
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the particular kernel configuration used. To generate them, use the ``rustdoc``
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target with the same invocation used for compilation, e.g.::
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make LLVM=1 rustdoc
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To read the docs locally in your web browser, run e.g.::
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xdg-open rust/doc/kernel/index.html
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To learn about how to write the documentation, please see coding-guidelines.rst.
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Extra lints
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-----------
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While ``rustc`` is a very helpful compiler, some extra lints and analyses are
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available via ``clippy``, a Rust linter. To enable it, pass ``CLIPPY=1`` to
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the same invocation used for compilation, e.g.::
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make LLVM=1 CLIPPY=1
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Please note that Clippy may change code generation, thus it should not be
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enabled while building a production kernel.
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Abstractions vs. bindings
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-------------------------
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Abstractions are Rust code wrapping kernel functionality from the C side.
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In order to use functions and types from the C side, bindings are created.
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Bindings are the declarations for Rust of those functions and types from
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the C side.
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For instance, one may write a ``Mutex`` abstraction in Rust which wraps
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a ``struct mutex`` from the C side and calls its functions through the bindings.
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Abstractions are not available for all the kernel internal APIs and concepts,
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but it is intended that coverage is expanded as time goes on. "Leaf" modules
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(e.g. drivers) should not use the C bindings directly. Instead, subsystems
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should provide as-safe-as-possible abstractions as needed.
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Conditional compilation
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-----------------------
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Rust code has access to conditional compilation based on the kernel
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configuration:
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.. code-block:: rust
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#[cfg(CONFIG_X)] // Enabled (`y` or `m`)
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#[cfg(CONFIG_X="y")] // Enabled as a built-in (`y`)
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#[cfg(CONFIG_X="m")] // Enabled as a module (`m`)
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#[cfg(not(CONFIG_X))] // Disabled
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