From 1dc4bbf0b268246f6202c761016735933b6f0b99 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Thu, 17 Nov 2016 08:32:33 -0200 Subject: docs-rst: doc-guide: split the kernel-documentation.rst contents Having the kernel-documentation at the topmost level doesn't allow generating a separate PDF file for it. Also, makes harder to add extra contents. So, place it on a sub-dir. Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Jonathan Corbet --- Documentation/00-INDEX | 2 +- Documentation/conf.py | 2 + Documentation/doc-guide/conf.py | 10 + Documentation/doc-guide/docbook.rst | 90 ++++ Documentation/doc-guide/index.rst | 19 + Documentation/doc-guide/kernel-doc.rst | 363 ++++++++++++++ Documentation/doc-guide/sphinx.rst | 219 +++++++++ Documentation/index.rst | 2 +- Documentation/kernel-doc-nano-HOWTO.txt | 2 +- Documentation/kernel-documentation.rst | 679 --------------------------- Documentation/process/4.Coding.rst | 4 +- Documentation/process/coding-style.rst | 4 +- Documentation/translations/zh_CN/CodingStyle | 2 +- 13 files changed, 711 insertions(+), 687 deletions(-) create mode 100644 Documentation/doc-guide/conf.py create mode 100644 Documentation/doc-guide/docbook.rst create mode 100644 Documentation/doc-guide/index.rst create mode 100644 Documentation/doc-guide/kernel-doc.rst create mode 100644 Documentation/doc-guide/sphinx.rst delete mode 100644 Documentation/kernel-documentation.rst diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index e2e74448d425..c08de5574d48 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -258,7 +258,7 @@ kdump/ - directory with mini HowTo on getting the crash dump code to work. process/kernel-docs.rst - listing of various WWW + books that document kernel internals. -kernel-documentation.rst +doc-guide/ - how to write and format reStructuredText kernel documentation admin-guide/kernel-parameters.rst - summary listing of command line / boot prompt args for the kernel. diff --git a/Documentation/conf.py b/Documentation/conf.py index ba38bcf485a9..1ac958c0333d 100644 --- a/Documentation/conf.py +++ b/Documentation/conf.py @@ -340,6 +340,8 @@ if major == 1 and minor > 3: # (source start file, target name, title, # author, documentclass [howto, manual, or own class]). latex_documents = [ + ('doc-guide/index', 'kernel-doc-guide.tex', 'Linux Kernel Documentation Guide', + 'The kernel development community', 'manual'), ('admin-guide/index', 'linux-user.tex', 'Linux Kernel User Documentation', 'The kernel development community', 'manual'), ('core-api/index', 'core-api.tex', 'The kernel core API manual', diff --git a/Documentation/doc-guide/conf.py b/Documentation/doc-guide/conf.py new file mode 100644 index 000000000000..fd3731182d5a --- /dev/null +++ b/Documentation/doc-guide/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = 'Linux Kernel Documentation Guide' + +tags.add("subproject") + +latex_documents = [ + ('index', 'kernel-doc-guide.tex', 'Linux Kernel Documentation Guide', + 'The kernel development community', 'manual'), +] diff --git a/Documentation/doc-guide/docbook.rst b/Documentation/doc-guide/docbook.rst new file mode 100644 index 000000000000..d8bf04308b43 --- /dev/null +++ b/Documentation/doc-guide/docbook.rst @@ -0,0 +1,90 @@ +DocBook XML [DEPRECATED] +======================== + +.. attention:: + + This section describes the deprecated DocBook XML toolchain. Please do not + create new DocBook XML template files. Please consider converting existing + DocBook XML templates files to Sphinx/reStructuredText. + +Converting DocBook to Sphinx +---------------------------- + +Over time, we expect all of the documents under ``Documentation/DocBook`` to be +converted to Sphinx and reStructuredText. For most DocBook XML documents, a good +enough solution is to use the simple ``Documentation/sphinx/tmplcvt`` script, +which uses ``pandoc`` under the hood. For example:: + + $ cd Documentation/sphinx + $ ./tmplcvt ../DocBook/in.tmpl ../out.rst + +Then edit the resulting rst files to fix any remaining issues, and add the +document in the ``toctree`` in ``Documentation/index.rst``. + +Components of the kernel-doc system +----------------------------------- + +Many places in the source tree have extractable documentation in the form of +block comments above functions. The components of this system are: + +- ``scripts/kernel-doc`` + + This is a perl script that hunts for the block comments and can mark them up + directly into reStructuredText, DocBook, man, text, and HTML. (No, not + texinfo.) + +- ``Documentation/DocBook/*.tmpl`` + + These are XML template files, which are normal XML files with special + place-holders for where the extracted documentation should go. + +- ``scripts/docproc.c`` + + This is a program for converting XML template files into XML files. When a + file is referenced it is searched for symbols exported (EXPORT_SYMBOL), to be + able to distinguish between internal and external functions. + + It invokes kernel-doc, giving it the list of functions that are to be + documented. + + Additionally it is used to scan the XML template files to locate all the files + referenced herein. This is used to generate dependency information as used by + make. + +- ``Makefile`` + + The targets 'xmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used to build + DocBook XML files, PostScript files, PDF files, and html files in + Documentation/DocBook. The older target 'sgmldocs' is equivalent to 'xmldocs'. + +- ``Documentation/DocBook/Makefile`` + + This is where C files are associated with SGML templates. + +How to use kernel-doc comments in DocBook XML template files +------------------------------------------------------------ + +DocBook XML template files (\*.tmpl) are like normal XML files, except that they +can contain escape sequences where extracted documentation should be inserted. + +``!E`` is replaced by the documentation, in ````, for +functions that are exported using ``EXPORT_SYMBOL``: the function list is +collected from files listed in ``Documentation/DocBook/Makefile``. + +``!I`` is replaced by the documentation for functions that are **not** +exported using ``EXPORT_SYMBOL``. + +``!D`` is used to name additional files to search for functions +exported using ``EXPORT_SYMBOL``. + +``!F `` is replaced by the documentation, in +````, for the functions listed. + +``!P
`` is replaced by the contents of the ``DOC:`` +section titled ``
`` from ````. Spaces are allowed in +``
``; do not quote the ``
``. + +``!C`` is replaced by nothing, but makes the tools check that all DOC: +sections and documented functions, symbols, etc. are used. This makes sense to +use when you use ``!F`` or ``!P`` only and want to verify that all documentation +is included. diff --git a/Documentation/doc-guide/index.rst b/Documentation/doc-guide/index.rst new file mode 100644 index 000000000000..695b7b6cf6ed --- /dev/null +++ b/Documentation/doc-guide/index.rst @@ -0,0 +1,19 @@ +.. _doc_guide: + +================================= +How to write kernel documentation +================================= + +.. toctree:: + :maxdepth: 1 + + sphinx.rst + kernel-doc.rst + docbook.rst + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/doc-guide/kernel-doc.rst b/Documentation/doc-guide/kernel-doc.rst new file mode 100644 index 000000000000..afc95c9e9626 --- /dev/null +++ b/Documentation/doc-guide/kernel-doc.rst @@ -0,0 +1,363 @@ +Including kernel-doc comments +============================= + +The Linux kernel source files may contain structured documentation comments, or +kernel-doc comments to describe the functions and types and design of the +code. The documentation comments may be included to any of the reStructuredText +documents using a dedicated kernel-doc Sphinx directive extension. + +The kernel-doc directive is of the format:: + + .. kernel-doc:: source + :option: + +The *source* is the path to a source file, relative to the kernel source +tree. The following directive options are supported: + +export: *[source-pattern ...]* + Include documentation for all functions in *source* that have been exported + using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either in *source* or in any + of the files specified by *source-pattern*. + + The *source-pattern* is useful when the kernel-doc comments have been placed + in header files, while ``EXPORT_SYMBOL`` and ``EXPORT_SYMBOL_GPL`` are next to + the function definitions. + + Examples:: + + .. kernel-doc:: lib/bitmap.c + :export: + + .. kernel-doc:: include/net/mac80211.h + :export: net/mac80211/*.c + +internal: *[source-pattern ...]* + Include documentation for all functions and types in *source* that have + **not** been exported using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either + in *source* or in any of the files specified by *source-pattern*. + + Example:: + + .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c + :internal: + +doc: *title* + Include documentation for the ``DOC:`` paragraph identified by *title* in + *source*. Spaces are allowed in *title*; do not quote the *title*. The *title* + is only used as an identifier for the paragraph, and is not included in the + output. Please make sure to have an appropriate heading in the enclosing + reStructuredText document. + + Example:: + + .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c + :doc: High Definition Audio over HDMI and Display Port + +functions: *function* *[...]* + Include documentation for each *function* in *source*. + + Example:: + + .. kernel-doc:: lib/bitmap.c + :functions: bitmap_parselist bitmap_parselist_user + +Without options, the kernel-doc directive includes all documentation comments +from the source file. + +The kernel-doc extension is included in the kernel source tree, at +``Documentation/sphinx/kernel-doc.py``. Internally, it uses the +``scripts/kernel-doc`` script to extract the documentation comments from the +source. + +.. _kernel_doc: + +Writing kernel-doc comments +=========================== + +In order to provide embedded, "C" friendly, easy to maintain, but consistent and +extractable overview, function and type documentation, the Linux kernel has +adopted a consistent style for documentation comments. The format for this +documentation is called the kernel-doc format, described below. This style +embeds the documentation within the source files, using a few simple conventions +for adding documentation paragraphs and documenting functions and their +parameters, structures and unions and their members, enumerations, and typedefs. + +.. note:: The kernel-doc format is deceptively similar to gtk-doc or Doxygen, + yet distinctively different, for historical reasons. The kernel source + contains tens of thousands of kernel-doc comments. Please stick to the style + described here. + +The ``scripts/kernel-doc`` script is used by the Sphinx kernel-doc extension in +the documentation build to extract this embedded documentation into the various +HTML, PDF, and other format documents. + +In order to provide good documentation of kernel functions and data structures, +please use the following conventions to format your kernel-doc comments in the +Linux kernel source. + +How to format kernel-doc comments +--------------------------------- + +The opening comment mark ``/**`` is reserved for kernel-doc comments. Only +comments so marked will be considered by the ``kernel-doc`` tool. Use it only +for comment blocks that contain kernel-doc formatted comments. The usual ``*/`` +should be used as the closing comment marker. The lines in between should be +prefixed by `` * `` (space star space). + +The function and type kernel-doc comments should be placed just before the +function or type being described. The overview kernel-doc comments may be freely +placed at the top indentation level. + +Example kernel-doc function comment:: + + /** + * foobar() - Brief description of foobar. + * @arg: Description of argument of foobar. + * + * Longer description of foobar. + * + * Return: Description of return value of foobar. + */ + int foobar(int arg) + +The format is similar for documentation for structures, enums, paragraphs, +etc. See the sections below for details. + +The kernel-doc structure is extracted from the comments, and proper `Sphinx C +Domain`_ function and type descriptions with anchors are generated for them. The +descriptions are filtered for special kernel-doc highlights and +cross-references. See below for details. + +.. _Sphinx C Domain: http://www.sphinx-doc.org/en/stable/domains.html + +Highlights and cross-references +------------------------------- + +The following special patterns are recognized in the kernel-doc comment +descriptive text and converted to proper reStructuredText markup and `Sphinx C +Domain`_ references. + +.. attention:: The below are **only** recognized within kernel-doc comments, + **not** within normal reStructuredText documents. + +``funcname()`` + Function reference. + +``@parameter`` + Name of a function parameter. (No cross-referencing, just formatting.) + +``%CONST`` + Name of a constant. (No cross-referencing, just formatting.) + +``$ENVVAR`` + Name of an environment variable. (No cross-referencing, just formatting.) + +``&struct name`` + Structure reference. + +``&enum name`` + Enum reference. + +``&typedef name`` + Typedef reference. + +``&struct_name->member`` or ``&struct_name.member`` + Structure or union member reference. The cross-reference will be to the struct + or union definition, not the member directly. + +``&name`` + A generic type reference. Prefer using the full reference described above + instead. This is mostly for legacy comments. + +Cross-referencing from reStructuredText +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To cross-reference the functions and types defined in the kernel-doc comments +from reStructuredText documents, please use the `Sphinx C Domain`_ +references. For example:: + + See function :c:func:`foo` and struct/union/enum/typedef :c:type:`bar`. + +While the type reference works with just the type name, without the +struct/union/enum/typedef part in front, you may want to use:: + + See :c:type:`struct foo `. + See :c:type:`union bar `. + See :c:type:`enum baz `. + See :c:type:`typedef meh `. + +This will produce prettier links, and is in line with how kernel-doc does the +cross-references. + +For further details, please refer to the `Sphinx C Domain`_ documentation. + +Function documentation +---------------------- + +The general format of a function and function-like macro kernel-doc comment is:: + + /** + * function_name() - Brief description of function. + * @arg1: Describe the first argument. + * @arg2: Describe the second argument. + * One can provide multiple line descriptions + * for arguments. + * + * A longer description, with more discussion of the function function_name() + * that might be useful to those using or modifying it. Begins with an + * empty comment line, and may include additional embedded empty + * comment lines. + * + * The longer description may have multiple paragraphs. + * + * Return: Describe the return value of foobar. + * + * The return value description can also have multiple paragraphs, and should + * be placed at the end of the comment block. + */ + +The brief description following the function name may span multiple lines, and +ends with an ``@argument:`` description, a blank comment line, or the end of the +comment block. + +The kernel-doc function comments describe each parameter to the function, in +order, with the ``@argument:`` descriptions. The ``@argument:`` descriptions +must begin on the very next line following the opening brief function +description line, with no intervening blank comment lines. The ``@argument:`` +descriptions may span multiple lines. The continuation lines may contain +indentation. If a function parameter is ``...`` (varargs), it should be listed +in kernel-doc notation as: ``@...:``. + +The return value, if any, should be described in a dedicated section at the end +of the comment starting with "Return:". + +Structure, union, and enumeration documentation +----------------------------------------------- + +The general format of a struct, union, and enum kernel-doc comment is:: + + /** + * struct struct_name - Brief description. + * @member_name: Description of member member_name. + * + * Description of the structure. + */ + +Below, "struct" is used to mean structs, unions and enums, and "member" is used +to mean struct and union members as well as enumerations in an enum. + +The brief description following the structure name may span multiple lines, and +ends with a ``@member:`` description, a blank comment line, or the end of the +comment block. + +The kernel-doc data structure comments describe each member of the structure, in +order, with the ``@member:`` descriptions. The ``@member:`` descriptions must +begin on the very next line following the opening brief function description +line, with no intervening blank comment lines. The ``@member:`` descriptions may +span multiple lines. The continuation lines may contain indentation. + +In-line member documentation comments +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The structure members may also be documented in-line within the definition:: + + /** + * struct foo - Brief description. + * @foo: The Foo member. + */ + struct foo { + int foo; + /** + * @bar: The Bar member. + */ + int bar; + /** + * @baz: The Baz member. + * + * Here, the member description may contain several paragraphs. + */ + int baz; + } + +Private members +~~~~~~~~~~~~~~~ + +Inside a struct description, you can use the "private:" and "public:" comment +tags. Structure fields that are inside a "private:" area are not listed in the +generated output documentation. The "private:" and "public:" tags must begin +immediately following a ``/*`` comment marker. They may optionally include +comments between the ``:`` and the ending ``*/`` marker. + +Example:: + + /** + * struct my_struct - short description + * @a: first member + * @b: second member + * + * Longer description + */ + struct my_struct { + int a; + int b; + /* private: internal use only */ + int c; + }; + + +Typedef documentation +--------------------- + +The general format of a typedef kernel-doc comment is:: + + /** + * typedef type_name - Brief description. + * + * Description of the type. + */ + +Overview documentation comments +------------------------------- + +To facilitate having source code and comments close together, you can include +kernel-doc documentation blocks that are free-form comments instead of being +kernel-doc for functions, structures, unions, enums, or typedefs. This could be +used for something like a theory of operation for a driver or library code, for +example. + +This is done by using a ``DOC:`` section keyword with a section title. + +The general format of an overview or high-level documentation comment is:: + + /** + * DOC: Theory of Operation + * + * The whizbang foobar is a dilly of a gizmo. It can do whatever you + * want it to do, at any time. It reads your mind. Here's how it works. + * + * foo bar splat + * + * The only drawback to this gizmo is that is can sometimes damage + * hardware, software, or its subject(s). + */ + +The title following ``DOC:`` acts as a heading within the source file, but also +as an identifier for extracting the documentation comment. Thus, the title must +be unique within the file. + +Recommendations +--------------- + +We definitely need kernel-doc formatted documentation for functions that are +exported to loadable modules using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL``. + +We also look to provide kernel-doc formatted documentation for functions +externally visible to other kernel files (not marked "static"). + +We also recommend providing kernel-doc formatted documentation for private (file +"static") routines, for consistency of kernel source code layout. But this is +lower priority and at the discretion of the MAINTAINER of that kernel source +file. + +Data structures visible in kernel include files should also be documented using +kernel-doc formatted comments. diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst new file mode 100644 index 000000000000..96fe7ccb2c67 --- /dev/null +++ b/Documentation/doc-guide/sphinx.rst @@ -0,0 +1,219 @@ +Introduction +============ + +The Linux kernel uses `Sphinx`_ to generate pretty documentation from +`reStructuredText`_ files under ``Documentation``. To build the documentation in +HTML or PDF formats, use ``make htmldocs`` or ``make pdfdocs``. The generated +documentation is placed in ``Documentation/output``. + +.. _Sphinx: http://www.sphinx-doc.org/ +.. _reStructuredText: http://docutils.sourceforge.net/rst.html + +The reStructuredText files may contain directives to include structured +documentation comments, or kernel-doc comments, from source files. Usually these +are used to describe the functions and types and design of the code. The +kernel-doc comments have some special structure and formatting, but beyond that +they are also treated as reStructuredText. + +There is also the deprecated DocBook toolchain to generate documentation from +DocBook XML template files under ``Documentation/DocBook``. The DocBook files +are to be converted to reStructuredText, and the toolchain is slated to be +removed. + +Finally, there are thousands of plain text documentation files scattered around +``Documentation``. Some of these will likely be converted to reStructuredText +over time, but the bulk of them will remain in plain text. + +Sphinx Build +============ + +The usual way to generate the documentation is to run ``make htmldocs`` or +``make pdfdocs``. There are also other formats available, see the documentation +section of ``make help``. The generated documentation is placed in +format-specific subdirectories under ``Documentation/output``. + +To generate documentation, Sphinx (``sphinx-build``) must obviously be +installed. For prettier HTML output, the Read the Docs Sphinx theme +(``sphinx_rtd_theme``) is used if available. For PDF output, ``rst2pdf`` is also +needed. All of these are widely available and packaged in distributions. + +To pass extra options to Sphinx, you can use the ``SPHINXOPTS`` make +variable. For example, use ``make SPHINXOPTS=-v htmldocs`` to get more verbose +output. + +To remove the generated documentation, run ``make cleandocs``. + +Writing Documentation +===================== + +Adding new documentation can be as simple as: + +1. Add a new ``.rst`` file somewhere under ``Documentation``. +2. Refer to it from the Sphinx main `TOC tree`_ in ``Documentation/index.rst``. + +.. _TOC tree: http://www.sphinx-doc.org/en/stable/markup/toctree.html + +This is usually good enough for simple documentation (like the one you're +reading right now), but for larger documents it may be advisable to create a +subdirectory (or use an existing one). For example, the graphics subsystem +documentation is under ``Documentation/gpu``, split to several ``.rst`` files, +and has a separate ``index.rst`` (with a ``toctree`` of its own) referenced from +the main index. + +See the documentation for `Sphinx`_ and `reStructuredText`_ on what you can do +with them. In particular, the Sphinx `reStructuredText Primer`_ is a good place +to get started with reStructuredText. There are also some `Sphinx specific +markup constructs`_. + +.. _reStructuredText Primer: http://www.sphinx-doc.org/en/stable/rest.html +.. _Sphinx specific markup constructs: http://www.sphinx-doc.org/en/stable/markup/index.html + +Specific guidelines for the kernel documentation +------------------------------------------------ + +Here are some specific guidelines for the kernel documentation: + +* Please don't go overboard with reStructuredText markup. Keep it simple. + +* Please stick to this order of heading adornments: + + 1. ``=`` with overline for document title:: + + ============== + Document title + ============== + + 2. ``=`` for chapters:: + + Chapters + ======== + + 3. ``-`` for sections:: + + Section + ------- + + 4. ``~`` for subsections:: + + Subsection + ~~~~~~~~~~ + + Although RST doesn't mandate a specific order ("Rather than imposing a fixed + number and order of section title adornment styles, the order enforced will be + the order as encountered."), having the higher levels the same overall makes + it easier to follow the documents. + + +the C domain +------------ + +The `Sphinx C Domain`_ (name c) is suited for documentation of C API. E.g. a +function prototype: + +.. code-block:: rst + + .. c:function:: int ioctl( int fd, int request ) + +The C domain of the kernel-doc has some additional features. E.g. you can +*rename* the reference name of a function with a common name like ``open`` or +``ioctl``: + +.. code-block:: rst + + .. c:function:: int ioctl( int fd, int request ) + :name: VIDIOC_LOG_STATUS + +The func-name (e.g. ioctl) remains in the output but the ref-name changed from +``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also +changed to ``VIDIOC_LOG_STATUS`` and the function can now referenced by: + +.. code-block:: rst + + :c:func:`VIDIOC_LOG_STATUS` + + +list tables +----------- + +We recommend the use of *list table* formats. The *list table* formats are +double-stage lists. Compared to the ASCII-art they might not be as +comfortable for +readers of the text files. Their advantage is that they are easy to +create or modify and that the diff of a modification is much more meaningful, +because it is limited to the modified content. + +The ``flat-table`` is a double-stage list similar to the ``list-table`` with +some additional features: + +* column-span: with the role ``cspan`` a cell can be extended through + additional columns + +* row-span: with the role ``rspan`` a cell can be extended through + additional rows + +* auto span rightmost cell of a table row over the missing cells on the right + side of that table-row. With Option ``:fill-cells:`` this behavior can + changed from *auto span* to *auto fill*, which automatically inserts (empty) + cells instead of spanning the last cell. + +options: + +* ``:header-rows:`` [int] count of header rows +* ``:stub-columns:`` [int] count of stub columns +* ``:widths:`` [[int] [int] ... ] widths of columns +* ``:fill-cells:`` instead of auto-spanning missing cells, insert missing cells + +roles: + +* ``:cspan:`` [int] additional columns (*morecols*) +* ``:rspan:`` [int] additional rows (*morerows*) + +The example below shows how to use this markup. The first level of the staged +list is the *table-row*. In the *table-row* there is only one markup allowed, +the list of the cells in this *table-row*. Exceptions are *comments* ( ``..`` ) +and *targets* (e.g. a ref to ``:ref:`last row ``` / :ref:`last row +`). + +.. code-block:: rst + + .. flat-table:: table title + :widths: 2 1 1 3 + + * - head col 1 + - head col 2 + - head col 3 + - head col 4 + + * - column 1 + - field 1.1 + - field 1.2 with autospan + + * - column 2 + - field 2.1 + - :rspan:`1` :cspan:`1` field 2.2 - 3.3 + + * .. _`last row`: + + - column 3 + +Rendered as: + + .. flat-table:: table title + :widths: 2 1 1 3 + + * - head col 1 + - head col 2 + - head col 3 + - head col 4 + + * - column 1 + - field 1.1 + - field 1.2 with autospan + + * - column 2 + - field 2.1 + - :rspan:`1` :cspan:`1` field 2.2 - 3.3 + + * .. _`last row`: + + - column 3 diff --git a/Documentation/index.rst b/Documentation/index.rst index 286d92bad208..bf3eb3ad6ad5 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -38,7 +38,7 @@ merged much easier. process/index dev-tools/index - kernel-documentation + doc-guide/index Kernel API documentation ------------------------ diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 062e3af271b7..104740ea0041 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -1,5 +1,5 @@ NOTE: this document is outdated and will eventually be removed. See -Documentation/kernel-documentation.rst for current information. +Documentation/doc-guide/ for current information. kernel-doc nano-HOWTO ===================== diff --git a/Documentation/kernel-documentation.rst b/Documentation/kernel-documentation.rst deleted file mode 100644 index c66ab937c2ca..000000000000 --- a/Documentation/kernel-documentation.rst +++ /dev/null @@ -1,679 +0,0 @@ -================================= -How to write kernel documentation -================================= - -Introduction -============ - -The Linux kernel uses `Sphinx`_ to generate pretty documentation from -`reStructuredText`_ files under ``Documentation``. To build the documentation in -HTML or PDF formats, use ``make htmldocs`` or ``make pdfdocs``. The generated -documentation is placed in ``Documentation/output``. - -.. _Sphinx: http://www.sphinx-doc.org/ -.. _reStructuredText: http://docutils.sourceforge.net/rst.html - -The reStructuredText files may contain directives to include structured -documentation comments, or kernel-doc comments, from source files. Usually these -are used to describe the functions and types and design of the code. The -kernel-doc comments have some special structure and formatting, but beyond that -they are also treated as reStructuredText. - -There is also the deprecated DocBook toolchain to generate documentation from -DocBook XML template files under ``Documentation/DocBook``. The DocBook files -are to be converted to reStructuredText, and the toolchain is slated to be -removed. - -Finally, there are thousands of plain text documentation files scattered around -``Documentation``. Some of these will likely be converted to reStructuredText -over time, but the bulk of them will remain in plain text. - -Sphinx Build -============ - -The usual way to generate the documentation is to run ``make htmldocs`` or -``make pdfdocs``. There are also other formats available, see the documentation -section of ``make help``. The generated documentation is placed in -format-specific subdirectories under ``Documentation/output``. - -To generate documentation, Sphinx (``sphinx-build``) must obviously be -installed. For prettier HTML output, the Read the Docs Sphinx theme -(``sphinx_rtd_theme``) is used if available. For PDF output, ``rst2pdf`` is also -needed. All of these are widely available and packaged in distributions. - -To pass extra options to Sphinx, you can use the ``SPHINXOPTS`` make -variable. For example, use ``make SPHINXOPTS=-v htmldocs`` to get more verbose -output. - -To remove the generated documentation, run ``make cleandocs``. - -Writing Documentation -===================== - -Adding new documentation can be as simple as: - -1. Add a new ``.rst`` file somewhere under ``Documentation``. -2. Refer to it from the Sphinx main `TOC tree`_ in ``Documentation/index.rst``. - -.. _TOC tree: http://www.sphinx-doc.org/en/stable/markup/toctree.html - -This is usually good enough for simple documentation (like the one you're -reading right now), but for larger documents it may be advisable to create a -subdirectory (or use an existing one). For example, the graphics subsystem -documentation is under ``Documentation/gpu``, split to several ``.rst`` files, -and has a separate ``index.rst`` (with a ``toctree`` of its own) referenced from -the main index. - -See the documentation for `Sphinx`_ and `reStructuredText`_ on what you can do -with them. In particular, the Sphinx `reStructuredText Primer`_ is a good place -to get started with reStructuredText. There are also some `Sphinx specific -markup constructs`_. - -.. _reStructuredText Primer: http://www.sphinx-doc.org/en/stable/rest.html -.. _Sphinx specific markup constructs: http://www.sphinx-doc.org/en/stable/markup/index.html - -Specific guidelines for the kernel documentation ------------------------------------------------- - -Here are some specific guidelines for the kernel documentation: - -* Please don't go overboard with reStructuredText markup. Keep it simple. - -* Please stick to this order of heading adornments: - - 1. ``=`` with overline for document title:: - - ============== - Document title - ============== - - 2. ``=`` for chapters:: - - Chapters - ======== - - 3. ``-`` for sections:: - - Section - ------- - - 4. ``~`` for subsections:: - - Subsection - ~~~~~~~~~~ - - Although RST doesn't mandate a specific order ("Rather than imposing a fixed - number and order of section title adornment styles, the order enforced will be - the order as encountered."), having the higher levels the same overall makes - it easier to follow the documents. - - -the C domain ------------- - -The `Sphinx C Domain`_ (name c) is suited for documentation of C API. E.g. a -function prototype: - -.. code-block:: rst - - .. c:function:: int ioctl( int fd, int request ) - -The C domain of the kernel-doc has some additional features. E.g. you can -*rename* the reference name of a function with a common name like ``open`` or -``ioctl``: - -.. code-block:: rst - - .. c:function:: int ioctl( int fd, int request ) - :name: VIDIOC_LOG_STATUS - -The func-name (e.g. ioctl) remains in the output but the ref-name changed from -``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also -changed to ``VIDIOC_LOG_STATUS`` and the function can now referenced by: - -.. code-block:: rst - - :c:func:`VIDIOC_LOG_STATUS` - - -list tables ------------ - -We recommend the use of *list table* formats. The *list table* formats are -double-stage lists. Compared to the ASCII-art they might not be as -comfortable for -readers of the text files. Their advantage is that they are easy to -create or modify and that the diff of a modification is much more meaningful, -because it is limited to the modified content. - -The ``flat-table`` is a double-stage list similar to the ``list-table`` with -some additional features: - -* column-span: with the role ``cspan`` a cell can be extended through - additional columns - -* row-span: with the role ``rspan`` a cell can be extended through - additional rows - -* auto span rightmost cell of a table row over the missing cells on the right - side of that table-row. With Option ``:fill-cells:`` this behavior can - changed from *auto span* to *auto fill*, which automatically inserts (empty) - cells instead of spanning the last cell. - -options: - -* ``:header-rows:`` [int] count of header rows -* ``:stub-columns:`` [int] count of stub columns -* ``:widths:`` [[int] [int] ... ] widths of columns -* ``:fill-cells:`` instead of auto-spanning missing cells, insert missing cells - -roles: - -* ``:cspan:`` [int] additional columns (*morecols*) -* ``:rspan:`` [int] additional rows (*morerows*) - -The example below shows how to use this markup. The first level of the staged -list is the *table-row*. In the *table-row* there is only one markup allowed, -the list of the cells in this *table-row*. Exceptions are *comments* ( ``..`` ) -and *targets* (e.g. a ref to ``:ref:`last row ``` / :ref:`last row -`). - -.. code-block:: rst - - .. flat-table:: table title - :widths: 2 1 1 3 - - * - head col 1 - - head col 2 - - head col 3 - - head col 4 - - * - column 1 - - field 1.1 - - field 1.2 with autospan - - * - column 2 - - field 2.1 - - :rspan:`1` :cspan:`1` field 2.2 - 3.3 - - * .. _`last row`: - - - column 3 - -Rendered as: - - .. flat-table:: table title - :widths: 2 1 1 3 - - * - head col 1 - - head col 2 - - head col 3 - - head col 4 - - * - column 1 - - field 1.1 - - field 1.2 with autospan - - * - column 2 - - field 2.1 - - :rspan:`1` :cspan:`1` field 2.2 - 3.3 - - * .. _`last row`: - - - column 3 - - -Including kernel-doc comments -============================= - -The Linux kernel source files may contain structured documentation comments, or -kernel-doc comments to describe the functions and types and design of the -code. The documentation comments may be included to any of the reStructuredText -documents using a dedicated kernel-doc Sphinx directive extension. - -The kernel-doc directive is of the format:: - - .. kernel-doc:: source - :option: - -The *source* is the path to a source file, relative to the kernel source -tree. The following directive options are supported: - -export: *[source-pattern ...]* - Include documentation for all functions in *source* that have been exported - using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either in *source* or in any - of the files specified by *source-pattern*. - - The *source-pattern* is useful when the kernel-doc comments have been placed - in header files, while ``EXPORT_SYMBOL`` and ``EXPORT_SYMBOL_GPL`` are next to - the function definitions. - - Examples:: - - .. kernel-doc:: lib/bitmap.c - :export: - - .. kernel-doc:: include/net/mac80211.h - :export: net/mac80211/*.c - -internal: *[source-pattern ...]* - Include documentation for all functions and types in *source* that have - **not** been exported using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either - in *source* or in any of the files specified by *source-pattern*. - - Example:: - - .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c - :internal: - -doc: *title* - Include documentation for the ``DOC:`` paragraph identified by *title* in - *source*. Spaces are allowed in *title*; do not quote the *title*. The *title* - is only used as an identifier for the paragraph, and is not included in the - output. Please make sure to have an appropriate heading in the enclosing - reStructuredText document. - - Example:: - - .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c - :doc: High Definition Audio over HDMI and Display Port - -functions: *function* *[...]* - Include documentation for each *function* in *source*. - - Example:: - - .. kernel-doc:: lib/bitmap.c - :functions: bitmap_parselist bitmap_parselist_user - -Without options, the kernel-doc directive includes all documentation comments -from the source file. - -The kernel-doc extension is included in the kernel source tree, at -``Documentation/sphinx/kernel-doc.py``. Internally, it uses the -``scripts/kernel-doc`` script to extract the documentation comments from the -source. - -.. _kernel_doc: - -Writing kernel-doc comments -=========================== - -In order to provide embedded, "C" friendly, easy to maintain, but consistent and -extractable overview, function and type documentation, the Linux kernel has -adopted a consistent style for documentation comments. The format for this -documentation is called the kernel-doc format, described below. This style -embeds the documentation within the source files, using a few simple conventions -for adding documentation paragraphs and documenting functions and their -parameters, structures and unions and their members, enumerations, and typedefs. - -.. note:: The kernel-doc format is deceptively similar to gtk-doc or Doxygen, - yet distinctively different, for historical reasons. The kernel source - contains tens of thousands of kernel-doc comments. Please stick to the style - described here. - -The ``scripts/kernel-doc`` script is used by the Sphinx kernel-doc extension in -the documentation build to extract this embedded documentation into the various -HTML, PDF, and other format documents. - -In order to provide good documentation of kernel functions and data structures, -please use the following conventions to format your kernel-doc comments in the -Linux kernel source. - -How to format kernel-doc comments ---------------------------------- - -The opening comment mark ``/**`` is reserved for kernel-doc comments. Only -comments so marked will be considered by the ``kernel-doc`` tool. Use it only -for comment blocks that contain kernel-doc formatted comments. The usual ``*/`` -should be used as the closing comment marker. The lines in between should be -prefixed by `` * `` (space star space). - -The function and type kernel-doc comments should be placed just before the -function or type being described. The overview kernel-doc comments may be freely -placed at the top indentation level. - -Example kernel-doc function comment:: - - /** - * foobar() - Brief description of foobar. - * @arg: Description of argument of foobar. - * - * Longer description of foobar. - * - * Return: Description of return value of foobar. - */ - int foobar(int arg) - -The format is similar for documentation for structures, enums, paragraphs, -etc. See the sections below for details. - -The kernel-doc structure is extracted from the comments, and proper `Sphinx C -Domain`_ function and type descriptions with anchors are generated for them. The -descriptions are filtered for special kernel-doc highlights and -cross-references. See below for details. - -.. _Sphinx C Domain: http://www.sphinx-doc.org/en/stable/domains.html - -Highlights and cross-references -------------------------------- - -The following special patterns are recognized in the kernel-doc comment -descriptive text and converted to proper reStructuredText markup and `Sphinx C -Domain`_ references. - -.. attention:: The below are **only** recognized within kernel-doc comments, - **not** within normal reStructuredText documents. - -``funcname()`` - Function reference. - -``@parameter`` - Name of a function parameter. (No cross-referencing, just formatting.) - -``%CONST`` - Name of a constant. (No cross-referencing, just formatting.) - -``$ENVVAR`` - Name of an environment variable. (No cross-referencing, just formatting.) - -``&struct name`` - Structure reference. - -``&enum name`` - Enum reference. - -``&typedef name`` - Typedef reference. - -``&struct_name->member`` or ``&struct_name.member`` - Structure or union member reference. The cross-reference will be to the struct - or union definition, not the member directly. - -``&name`` - A generic type reference. Prefer using the full reference described above - instead. This is mostly for legacy comments. - -Cross-referencing from reStructuredText -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -To cross-reference the functions and types defined in the kernel-doc comments -from reStructuredText documents, please use the `Sphinx C Domain`_ -references. For example:: - - See function :c:func:`foo` and struct/union/enum/typedef :c:type:`bar`. - -While the type reference works with just the type name, without the -struct/union/enum/typedef part in front, you may want to use:: - - See :c:type:`struct foo `. - See :c:type:`union bar `. - See :c:type:`enum baz `. - See :c:type:`typedef meh `. - -This will produce prettier links, and is in line with how kernel-doc does the -cross-references. - -For further details, please refer to the `Sphinx C Domain`_ documentation. - -Function documentation ----------------------- - -The general format of a function and function-like macro kernel-doc comment is:: - - /** - * function_name() - Brief description of function. - * @arg1: Describe the first argument. - * @arg2: Describe the second argument. - * One can provide multiple line descriptions - * for arguments. - * - * A longer description, with more discussion of the function function_name() - * that might be useful to those using or modifying it. Begins with an - * empty comment line, and may include additional embedded empty - * comment lines. - * - * The longer description may have multiple paragraphs. - * - * Return: Describe the return value of foobar. - * - * The return value description can also have multiple paragraphs, and should - * be placed at the end of the comment block. - */ - -The brief description following the function name may span multiple lines, and -ends with an ``@argument:`` description, a blank comment line, or the end of the -comment block. - -The kernel-doc function comments describe each parameter to the function, in -order, with the ``@argument:`` descriptions. The ``@argument:`` descriptions -must begin on the very next line following the opening brief function -description line, with no intervening blank comment lines. The ``@argument:`` -descriptions may span multiple lines. The continuation lines may contain -indentation. If a function parameter is ``...`` (varargs), it should be listed -in kernel-doc notation as: ``@...:``. - -The return value, if any, should be described in a dedicated section at the end -of the comment starting with "Return:". - -Structure, union, and enumeration documentation ------------------------------------------------ - -The general format of a struct, union, and enum kernel-doc comment is:: - - /** - * struct struct_name - Brief description. - * @member_name: Description of member member_name. - * - * Description of the structure. - */ - -Below, "struct" is used to mean structs, unions and enums, and "member" is used -to mean struct and union members as well as enumerations in an enum. - -The brief description following the structure name may span multiple lines, and -ends with a ``@member:`` description, a blank comment line, or the end of the -comment block. - -The kernel-doc data structure comments describe each member of the structure, in -order, with the ``@member:`` descriptions. The ``@member:`` descriptions must -begin on the very next line following the opening brief function description -line, with no intervening blank comment lines. The ``@member:`` descriptions may -span multiple lines. The continuation lines may contain indentation. - -In-line member documentation comments -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The structure members may also be documented in-line within the definition:: - - /** - * struct foo - Brief description. - * @foo: The Foo member. - */ - struct foo { - int foo; - /** - * @bar: The Bar member. - */ - int bar; - /** - * @baz: The Baz member. - * - * Here, the member description may contain several paragraphs. - */ - int baz; - } - -Private members -~~~~~~~~~~~~~~~ - -Inside a struct description, you can use the "private:" and "public:" comment -tags. Structure fields that are inside a "private:" area are not listed in the -generated output documentation. The "private:" and "public:" tags must begin -immediately following a ``/*`` comment marker. They may optionally include -comments between the ``:`` and the ending ``*/`` marker. - -Example:: - - /** - * struct my_struct - short description - * @a: first member - * @b: second member - * - * Longer description - */ - struct my_struct { - int a; - int b; - /* private: internal use only */ - int c; - }; - - -Typedef documentation ---------------------- - -The general format of a typedef kernel-doc comment is:: - - /** - * typedef type_name - Brief description. - * - * Description of the type. - */ - -Overview documentation comments -------------------------------- - -To facilitate having source code and comments close together, you can include -kernel-doc documentation blocks that are free-form comments instead of being -kernel-doc for functions, structures, unions, enums, or typedefs. This could be -used for something like a theory of operation for a driver or library code, for -example. - -This is done by using a ``DOC:`` section keyword with a section title. - -The general format of an overview or high-level documentation comment is:: - - /** - * DOC: Theory of Operation - * - * The whizbang foobar is a dilly of a gizmo. It can do whatever you - * want it to do, at any time. It reads your mind. Here's how it works. - * - * foo bar splat - * - * The only drawback to this gizmo is that is can sometimes damage - * hardware, software, or its subject(s). - */ - -The title following ``DOC:`` acts as a heading within the source file, but also -as an identifier for extracting the documentation comment. Thus, the title must -be unique within the file. - -Recommendations ---------------- - -We definitely need kernel-doc formatted documentation for functions that are -exported to loadable modules using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL``. - -We also look to provide kernel-doc formatted documentation for functions -externally visible to other kernel files (not marked "static"). - -We also recommend providing kernel-doc formatted documentation for private (file -"static") routines, for consistency of kernel source code layout. But this is -lower priority and at the discretion of the MAINTAINER of that kernel source -file. - -Data structures visible in kernel include files should also be documented using -kernel-doc formatted comments. - -DocBook XML [DEPRECATED] -======================== - -.. attention:: - - This section describes the deprecated DocBook XML toolchain. Please do not - create new DocBook XML template files. Please consider converting existing - DocBook XML templates files to Sphinx/reStructuredText. - -Converting DocBook to Sphinx ----------------------------- - -Over time, we expect all of the documents under ``Documentation/DocBook`` to be -converted to Sphinx and reStructuredText. For most DocBook XML documents, a good -enough solution is to use the simple ``Documentation/sphinx/tmplcvt`` script, -which uses ``pandoc`` under the hood. For example:: - - $ cd Documentation/sphinx - $ ./tmplcvt ../DocBook/in.tmpl ../out.rst - -Then edit the resulting rst files to fix any remaining issues, and add the -document in the ``toctree`` in ``Documentation/index.rst``. - -Components of the kernel-doc system ------------------------------------ - -Many places in the source tree have extractable documentation in the form of -block comments above functions. The components of this system are: - -- ``scripts/kernel-doc`` - - This is a perl script that hunts for the block comments and can mark them up - directly into reStructuredText, DocBook, man, text, and HTML. (No, not - texinfo.) - -- ``Documentation/DocBook/*.tmpl`` - - These are XML template files, which are normal XML files with special - place-holders for where the extracted documentation should go. - -- ``scripts/docproc.c`` - - This is a program for converting XML template files into XML files. When a - file is referenced it is searched for symbols exported (EXPORT_SYMBOL), to be - able to distinguish between internal and external functions. - - It invokes kernel-doc, giving it the list of functions that are to be - documented. - - Additionally it is used to scan the XML template files to locate all the files - referenced herein. This is used to generate dependency information as used by - make. - -- ``Makefile`` - - The targets 'xmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used to build - DocBook XML files, PostScript files, PDF files, and html files in - Documentation/DocBook. The older target 'sgmldocs' is equivalent to 'xmldocs'. - -- ``Documentation/DocBook/Makefile`` - - This is where C files are associated with SGML templates. - -How to use kernel-doc comments in DocBook XML template files ------------------------------------------------------------- - -DocBook XML template files (\*.tmpl) are like normal XML files, except that they -can contain escape sequences where extracted documentation should be inserted. - -``!E`` is replaced by the documentation, in ````, for -functions that are exported using ``EXPORT_SYMBOL``: the function list is -collected from files listed in ``Documentation/DocBook/Makefile``. - -``!I`` is replaced by the documentation for functions that are **not** -exported using ``EXPORT_SYMBOL``. - -``!D`` is used to name additional files to search for functions -exported using ``EXPORT_SYMBOL``. - -``!F `` is replaced by the documentation, in -````, for the functions listed. - -``!P
`` is replaced by the contents of the ``DOC:`` -section titled ``
`` from ````. Spaces are allowed in -``
``; do not quote the ``
``. - -``!C`` is replaced by nothing, but makes the tools check that all DOC: -sections and documented functions, symbols, etc. are used. This makes sense to -use when you use ``!F`` or ``!P`` only and want to verify that all documentation -is included. diff --git a/Documentation/process/4.Coding.rst b/Documentation/process/4.Coding.rst index 983d628c1112..2a728d898fc5 100644 --- a/Documentation/process/4.Coding.rst +++ b/Documentation/process/4.Coding.rst @@ -358,8 +358,8 @@ them, as appropriate, for externally-available functions. Even in areas which have not been so documented, there is no harm in adding kerneldoc comments for the future; indeed, this can be a useful activity for beginning kernel developers. The format of these comments, along with some -information on how to create kerneldoc templates can be found in the file -Documentation/kernel-documentation.rst. +information on how to create kerneldoc templates can be found at +:ref:`Documentation/doc-guide/ `. Anybody who reads through a significant amount of existing kernel code will note that, often, comments are most notable by their absence. Once again, diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst index 3e7905172000..d20d52a4d812 100644 --- a/Documentation/process/coding-style.rst +++ b/Documentation/process/coding-style.rst @@ -525,8 +525,8 @@ of the function, telling people what it does, and possibly WHY it does it. When commenting the kernel API functions, please use the kernel-doc format. -See the files Documentation/kernel-documentation.rst and scripts/kernel-doc -for details. +See the files at :ref:`Documentation/doc-guide/ ` and +``scripts/kernel-doc`` for details. The preferred style for long (multi-line) comments is: diff --git a/Documentation/translations/zh_CN/CodingStyle b/Documentation/translations/zh_CN/CodingStyle index b02738042799..dc101f48e713 100644 --- a/Documentation/translations/zh_CN/CodingStyle +++ b/Documentation/translations/zh_CN/CodingStyle @@ -399,7 +399,7 @@ C是一个简朴的语言，你的命名也应该这样。和 Modula-2 和 Pasca 些事情的原因。 当注释内核API函数时，请使用 kernel-doc 格式。请看 -Documentation/kernel-documentation.rst和scripts/kernel-doc 以获得详细信息。 +Documentation/doc-guide/和scripts/kernel-doc 以获得详细信息。 Linux的注释风格是 C89 “/* ... */” 风格。不要使用 C99 风格 “// ...” 注释。 -- cgit v1.2.3