59 lines
2.6 KiB
ReStructuredText
59 lines
2.6 KiB
ReStructuredText
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.. _programming_language:
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Programming Language
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====================
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The kernel is written in the C programming language [c-language]_.
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More precisely, the kernel is typically compiled with ``gcc`` [gcc]_
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under ``-std=gnu11`` [gcc-c-dialect-options]_: the GNU dialect of ISO C11.
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``clang`` [clang]_ is also supported, see docs on
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:ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
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This dialect contains many extensions to the language [gnu-extensions]_,
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and many of them are used within the kernel as a matter of course.
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Attributes
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----------
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One of the common extensions used throughout the kernel are attributes
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[gcc-attribute-syntax]_. Attributes allow to introduce
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implementation-defined semantics to language entities (like variables,
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functions or types) without having to make significant syntactic changes
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to the language (e.g. adding a new keyword) [n2049]_.
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In some cases, attributes are optional (i.e. a compiler not supporting them
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should still produce proper code, even if it is slower or does not perform
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as many compile-time checks/diagnostics).
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The kernel defines pseudo-keywords (e.g. ``__pure``) instead of using
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directly the GNU attribute syntax (e.g. ``__attribute__((__pure__))``)
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in order to feature detect which ones can be used and/or to shorten the code.
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Please refer to ``include/linux/compiler_attributes.h`` for more information.
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Rust
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----
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The kernel has experimental support for the Rust programming language
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[rust-language]_ under ``CONFIG_RUST``. It is compiled with ``rustc`` [rustc]_
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under ``--edition=2021`` [rust-editions]_. Editions are a way to introduce
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small changes to the language that are not backwards compatible.
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On top of that, some unstable features [rust-unstable-features]_ are used in
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the kernel. Unstable features may change in the future, thus it is an important
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goal to reach a point where only stable features are used.
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Please refer to Documentation/rust/index.rst for more information.
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.. [c-language] http://www.open-std.org/jtc1/sc22/wg14/www/standards
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.. [gcc] https://gcc.gnu.org
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.. [clang] https://clang.llvm.org
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.. [gcc-c-dialect-options] https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html
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.. [gnu-extensions] https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html
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.. [gcc-attribute-syntax] https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html
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.. [n2049] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2049.pdf
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.. [rust-language] https://www.rust-lang.org
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.. [rustc] https://doc.rust-lang.org/rustc/
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.. [rust-editions] https://doc.rust-lang.org/edition-guide/editions/
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.. [rust-unstable-features] https://github.com/Rust-for-Linux/linux/issues/2
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