mirror of
https://github.com/torvalds/linux.git
synced 2024-11-19 10:31:48 +00:00
303d22c5fc
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # on top of v4.19-rc5, clang 7 Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
46 lines
2.0 KiB
ReStructuredText
46 lines
2.0 KiB
ReStructuredText
.. _programming_language:
|
|
|
|
Programming Language
|
|
====================
|
|
|
|
The kernel is written in the C programming language [c-language]_.
|
|
More precisely, the kernel is typically compiled with ``gcc`` [gcc]_
|
|
under ``-std=gnu89`` [gcc-c-dialect-options]_: the GNU dialect of ISO C90
|
|
(including some C99 features).
|
|
|
|
This dialect contains many extensions to the language [gnu-extensions]_,
|
|
and many of them are used within the kernel as a matter of course.
|
|
|
|
There is some support for compiling the kernel with ``clang`` [clang]_
|
|
and ``icc`` [icc]_ for several of the architectures, although at the time
|
|
of writing it is not completed, requiring third-party patches.
|
|
|
|
Attributes
|
|
----------
|
|
|
|
One of the common extensions used throughout the kernel are attributes
|
|
[gcc-attribute-syntax]_. Attributes allow to introduce
|
|
implementation-defined semantics to language entities (like variables,
|
|
functions or types) without having to make significant syntactic changes
|
|
to the language (e.g. adding a new keyword) [n2049]_.
|
|
|
|
In some cases, attributes are optional (i.e. a compiler not supporting them
|
|
should still produce proper code, even if it is slower or does not perform
|
|
as many compile-time checks/diagnostics).
|
|
|
|
The kernel defines pseudo-keywords (e.g. ``__pure``) instead of using
|
|
directly the GNU attribute syntax (e.g. ``__attribute__((__pure__))``)
|
|
in order to feature detect which ones can be used and/or to shorten the code.
|
|
|
|
Please refer to ``include/linux/compiler_attributes.h`` for more information.
|
|
|
|
.. [c-language] http://www.open-std.org/jtc1/sc22/wg14/www/standards
|
|
.. [gcc] https://gcc.gnu.org
|
|
.. [clang] https://clang.llvm.org
|
|
.. [icc] https://software.intel.com/en-us/c-compilers
|
|
.. [gcc-c-dialect-options] https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html
|
|
.. [gnu-extensions] https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html
|
|
.. [gcc-attribute-syntax] https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html
|
|
.. [n2049] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2049.pdf
|
|
|