[dpdk-dev] [PATCH 0/3] doc: added guidelines on dpdk documentation

[dpdk-dev] [PATCH 0/3] doc: added guidelines on dpdk documentation

[John McNamara]

This patchset:

* Adds guidelines on the purpose and structure of the DPDK documentation,
  how to build it and guidelines for creating it and adding to it.

* Also adds guidelines on how to format and submit a documentation patch.

* Moves and refactores the Doxygen guidelines from the Coding Style doc to
  the Documentation Guidelines doc.

As with the other guidelines the main idea is to document the status quo and
then modify/add to it over time.


John McNamara (3):
  doc: set the default literal block format
  doc: added guidelines on dpdk documentation
  doc: moved doxygen section to the doc guidelines

 doc/guides/conf.py                      |    1 +
 doc/guides/guidelines/coding_style.rst  |  126 +---
 doc/guides/guidelines/documentation.rst | 1005 +++++++++++++++++++++++++++++++
 doc/guides/guidelines/index.rst         |    2 +
 4 files changed, 1015 insertions(+), 119 deletions(-)
 create mode 100644 doc/guides/guidelines/documentation.rst

-- 
1.8.1.4

[dpdk-dev] [PATCH 1/3] doc: set the default literal block format

[John McNamara]

Set the default literal block format for Sphinx docs
to 'none' instead of the implicit default of 'python'.

This means that default :: blocks won't have any
highlighting applied. Explicit highlighting via
the code-block:: directive is already available and
in use in the docs.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/conf.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/guides/conf.py b/doc/guides/conf.py
index e1edffd..b2290b4 100644
--- a/doc/guides/conf.py
+++ b/doc/guides/conf.py
@@ -38,6 +38,7 @@ from pygments.formatters.latex import LatexFormatter
 project = 'DPDK'
 
 html_show_copyright = False
+highlight_language = 'none'
 
 version = subprocess.check_output(['make', '-sRrC', '../../', 'showversion']).decode('utf-8')
 release = version
-- 
1.8.1.4

[dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[John McNamara]

Added guidelines on the purpose and structure of the DPDK
documentation, how to build it and guidelines for creating it.

Also added guidelines on how to format and submit a documentation patch.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/guidelines/documentation.rst | 1005 +++++++++++++++++++++++++++++++
 doc/guides/guidelines/index.rst         |    2 +
 2 files changed, 1007 insertions(+)
 create mode 100644 doc/guides/guidelines/documentation.rst

diff --git a/doc/guides/guidelines/documentation.rst b/doc/guides/guidelines/documentation.rst
new file mode 100644
index 0000000..d3e5905
--- /dev/null
+++ b/doc/guides/guidelines/documentation.rst
@@ -0,0 +1,1005 @@
+g.. doc_guidelines:
+
+DPDK Documentation Guidelines
+=============================
+
+This document outlines the guidelines for writing the DPDK Guides and API
+documentation in RST and Doxygen format.
+
+It also explains the structure of the DPDK documentation and shows how to
+build the Html and PDF versions of the documents.
+
+It also explains how to submit a patch to the documentation.
+
+
+Structure of the Documentation
+------------------------------
+
+The DPDK source code repository contains input files to build the API
+documentation and User Guides.
+
+The main directories that contain files related to documentation are shown
+below::
+
+   lib
+   |-- librte_acl
+   |-- librte_cfgfile
+   |-- librte_cmdline
+   |-- librte_compat
+   |-- librte_eal
+   |   |-- ...
+   ...
+   doc
+   |-- api
+   +-- guides
+       |-- freebsd_gsg
+       |-- linux_gsg
+       |-- prog_guide
+       |-- sample_app_ug
+       |-- guidelines
+       |-- testpmd_app_ug
+       |-- rel_notes
+       |-- nics
+       |-- xen
+       |-- ...
+
+
+The API documentation is built from `Doxygen
+<http://www.stack.nl/~dimitri/doxygen/>`_ comments in the header files. These
+files are mainly in the ``lib/lib_rte_*`` directories although some of the
+Poll Mode Drivers in ``drivers/net`` are also documented with Doxygen.
+
+The configuration files that are used to control the Doxygen output are in the
+``doc/api`` directory.
+
+The user guides such as *The Programmers Guide* and the *FreeBSD* and *Linux
+Getting Started* Guides are generated from RST markup text files using the
+`Sphinx <http://sphinx-doc.org/index.html>`_ Documentation Generator.
+
+These files are included in the ``doc/guides/`` directory. The output is
+controlled by the ``doc/guides/conf.py`` file.
+
+
+Role of the Documentation
+-------------------------
+
+The following items outline the roles of the different parts of the
+documentation and when they need to be updated or added to by the developer.
+
+* **Release Notes**
+
+  The Release Notes document which features have been added in the current and
+  previous releases of DPDK and highlight any known issues. The Releases Notes
+  also contain notifications of features that will change ABI compatibility in
+  the next major release.
+
+  In general developers do not have to update the Release Notes apart from
+  adding ABI announcements.
+
+* **API documentation**
+
+  The API documentation explains how to use the public DPDK functions. The
+  `API index page <http://dpdk.org/doc/api/>`_ shows the generated API
+  documentation as related groups of functions.
+
+  The API documentation should be updated via Doxygen comments when new
+  functions are added.
+
+* **Getting Started Guides**
+
+  The Getting Started Guides show how to install and configure DPDK and
+  how to run DPDK based applications on different OSes.
+
+  A Getting Started Guide should be added when DPDK is ported to a new OS. The
+  guide for the Skeleton Forwarding app is a good starting reference.
+
+* **The Programmers Guide**
+
+  The Programmers Guide explains how the API components of DPDK such as
+  the EAL, Memzone, Rings and the Hash Library work. It also explains how some
+  higher level functionality such as Packet Distributor, Packet Framework and
+  KNI work. It also shows the build system and explains how to add
+  applications.
+
+  The Programmers Guide should be expanded when new functionality is added to
+  DPDK.
+
+* **App Guides**
+
+  The app guides document the DPDK applications in the ``app`` directory such
+  as ``testpmd``.
+
+  The app guides should be updated if functionality is changed or added.
+
+* **Sample App Guides**
+
+  The sample app guides document the DPDK example applications in the examples
+  directory. Generally they demonstrate a major feature such as L2 or L3
+  Forwarding, Multi Process or Power Management. They explain the purpose of
+  the sample application, how to run it and step through some of the code to
+  explain the major functionality.
+
+  A new sample application should be accompanied by new sample app guide.
+
+* **Network Interface Controller Drivers**
+
+  The NIC Drivers document explains the features of the individual Poll Mode
+  Drivers, such as software requirements, configuration and initialization.
+
+  New documentation should be added for new Poll Mode Drivers.
+
+* **Guidelines**
+
+  The guideline documents record the DPDK guidelines on coding, design, ABI
+  usage and documentation.
+
+  These should be changed to clarify or improve guidelines.
+
+
+Building the Documentation
+--------------------------
+
+Dependencies
+~~~~~~~~~~~~
+
+
+The following dependencies must be installed to build the documentation:
+
+* Doxygen.
+
+* Sphinx.
+
+* TexLive.
+
+* Inkscape.
+
+`Doxygen`_ generates documentation from commented source code. It can be
+installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install doxygen
+
+   # Red Hat/Fedora.
+   sudo yum     -y install doxygen
+
+`Sphinx`_ is a Python documentation tool for converting RST files to Html or
+to PDF (via LaTeX). It can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install python-sphinx
+
+   # Red Hat/Fedora.
+   sudo yum     -y install python-sphinx
+
+   # Or, on any system with Python installed.
+   sudo easy_install -U sphinx
+
+For further information on getting started with Sphinx see the `Sphinx
+Tutorial <http://sphinx-doc.org/tutorial.html>`_.
+
+.. Note::
+
+   To get full support for Figure and Table numbering it is best to install
+   Sphinx 1.3.1 or later.
+
+
+`Inkscape`_ is a vector based graphics program which is used to create SVG
+images and also to convert SVG images to PDF images. It can be installed as
+follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install inkscape
+
+   # Red Hat/Fedora.
+   sudo yum     -y install inkscape
+
+`TexLive <http://www.tug.org/texlive/>`_ is an installation package for
+Tex/LaTeX. It is used to generate the PDF versions of the
+documentation. Installation of all of the TeX components required by Sphinx
+can be tricky. If possible it is best to install TexLive Full to ensure that
+you have all the requirements. It can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+
+   sudo apt-get -y install texlive-full
+
+   # Red Hat/Fedora, selective install.
+   sudo yum -y install texlive
+   sudo yum -y install texlive-latex
+   sudo yum -y install texlive-collection-latex
+   sudo yum -y install texlive-collection-latexrecommended
+   sudo yum -y install texlive-collection-latexextra
+   sudo yum -y install texlive-dejavu
+
+
+Build commands
+~~~~~~~~~~~~~~
+
+The documentation is built using the standard DPDK build system. Some examples
+are shown below:
+
+* Generate all the documentation targets::
+
+     make doc
+
+* Generate the Doxygen API documentation in Html::
+
+     make doc-api-html
+
+* Generate the guides documentation in Html::
+
+     make doc-guides-html
+
+* Generate the guides documentation in Pdf::
+
+     make doc-guides-pdf
+
+The output of these commands is generated in the ``build`` directory::
+
+   build/doc
+         |-- html
+         |   |-- api
+         |   +-- guides
+         |
+         +-- pdf
+             +-- guides
+
+
+.. Note::
+
+   Make sure to fix any Sphinx or Doxygen warnings when adding or updating
+   documentation.
+
+The documentation output files can be removed as follows::
+
+   make doc-clean
+
+
+Document Guidelines
+-------------------
+
+Here are some guidelines in relation to the style of the documentation:
+
+* Document the obvious as well as the obscure since it won't always be obvious
+  to the reader. For example an instruction like "Set up 64 2MB Hugepages" is
+  better when followed by a sample commandline or a link to the appropriate
+  section of the documentation.
+
+* Use American English spellings throughout. This can be checked using the
+  ``aspell`` utility::
+
+       aspell --lang=en_US --check doc/guides/sample_app_ug/mydoc.rst
+
+
+RST Guidelines
+--------------
+
+The RST (reStructuredText) format is a plain text markup format that can be
+converted to Html, PDF or other formats. It is most closely associated with
+Python but it can be used to document any language. It is used in DPDK to
+document everything apart from the API.
+
+The Sphinx documentation contains a very useful `RST Primer
+<http://sphinx-doc.org/rest.html#rst-primer>`_ which is a good place to learn
+the minimal set of syntax required to format a document.
+
+The official `reStructuredText <http://docutils.sourceforge.net/rst.html>`_
+website contains the specification for the RST format and also examples of how
+to use it. However, for most developers the RST Primer above is a better
+resource.
+
+The most common guidelines for writing RST text are detailed in the
+`Documenting Python <https://docs.python.org/devguide/documenting.html>`_
+guidelines. The additional guidelines below reiterate or expand upon those
+guidelines.
+
+
+Readability
+~~~~~~~~~~~
+
+The main RST guideline is that the RST text should be readable in text format.
+
+Even though RST is a markup format and the text will most often be read when
+rendered to Html or PDF it is important to maintain readability of the raw
+text. This makes is easier for developers to read in an editor or in a
+terminal.
+
+
+Line Length
+~~~~~~~~~~~
+
+The existing documentation contains different styles for long lines and
+paragraphs. The following are recommendations for new text in order of
+preference:
+
+* Wrap lines at 80 characters. This is the Python RST recommendation and adds
+  to readability of the raw text.
+
+* Use one sentence per line in a paragraph, i.e., put a newline character
+  after each period/full stop.
+
+* Use one line per paragraph.
+
+
+Whitespace
+~~~~~~~~~~
+
+* Standard RST indentation is 3 spaces. Code can be indented 4 spaces,
+  especially if it is copied from source files.
+
+* No tabs. Convert tabs in embedded code to 4 or 8 spaces.
+
+* No trailing whitespace.
+
+* The most common existing style in the documentation is to have only 1 space
+  after a period/full stop.
+
+* Add 2 blank lines before each section header.
+
+* Add 1 blank line after each section header.
+
+* Add 1 blank line between each line of a list.
+
+
+Section Headers
+~~~~~~~~~~~~~~~
+
+* Section headers should use the use the following underline formats::
+
+   Level 1 Heading
+   ===============
+
+
+   Level 2 Heading
+   ---------------
+
+
+   Level 3 Heading
+   ~~~~~~~~~~~~~~~
+
+
+   Level 4 Heading
+   ^^^^^^^^^^^^^^^
+
+
+* Level 4 headings should be used sparingly.
+
+* The underlines should match the length of the text.
+
+* In general, the heading should be less than 80 characters.
+
+* As noted above:
+
+   * Add 2 blank lines before each section header.
+
+   * Add 1 blank line after each section header.
+
+
+Lists
+~~~~~
+
+* Bullet lists should be formatted with a leading ``*`` as follows::
+
+     * Item one.
+
+     * Item two is a longer line that is wrapped at 80 characters and then
+       indented to match the start of the first line.
+
+     * One space character between the bullet and the text is preferred.
+
+* Numbered lists can be formatted with a leading number but the preference is
+  to use ``#.`` which will give automatic numbering. This is more convenient
+  when adding or removing items::
+
+     #. Item one.
+
+     #. Item two is a longer line that is wrapped at 80 characters and then
+        indented to match the start of the e first line.
+
+* Definition lists can be written with or without a bullet::
+
+     * Item one.
+
+       Some text about item one.
+
+     * Item two.
+
+       Some text about item two.
+
+* All lists, and sub-lists, must be separated from the preceding text by a
+  blank line. This is a syntax requirement.
+
+* All list items should be separated by a blank line for readability.
+
+
+Code and Literal block sections
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* Inline text that is required to be rendered with a fixed width font should
+  be enclosed in backquotes like this: \`\`text\`\`, so that it appears like
+  this: ``text``.
+
+* Fixed width, literal blocks of texts should be indented at least 3 spaces
+  and prefixed with ``::`` like this::
+
+     Here is some fixed width text::
+
+        0x0001 0x0001 0x00FF 0x00FF
+
+* It is also possible to specify an encoding for a literal block using the
+  ``.. code-block::`` directive so that syntax highlighting can be
+  applied. Examples of supported highlighting are::
+
+     .. code-block:: console
+     .. code-block:: c
+     .. code-block:: python
+     .. code-block:: diff
+     .. code-block:: none
+
+  That can be applied as follows::
+
+      .. code-block:: c
+
+         #include<stdio.h>
+
+         int main() {
+
+            printf("Hello World\n");
+
+            return 0;
+         }
+
+  Which would be rendered as:
+
+  .. code-block:: c
+
+      #include<stdio.h>
+
+      int main() {
+
+         printf("Hello World\n");
+
+         return 0;
+      }
+
+
+* The default encoding for a literal block using the simplified ``::``
+  directive is ``none``.
+
+* Avoid lines longer than 80 character in literal blocks since they can exceed
+  the page width when converted to PDF documentation. If possible try to wrap
+  the text at sensible locations. For example a long command line could be
+  documented like this and still work if copied directly from the docs::
+
+     build/app/testpmd -c7 -n3 --vdev=eth_pcap0,iface=eth0     \
+                               --vdev=eth_pcap1,iface=eth1     \
+                               -- -i --nb-cores=2 --nb-ports=2 \
+                                  --total-num-mbufs=2048
+
+
+Images
+~~~~~~
+
+* All images should be in SVG scalar graphics format. They should be true SVG
+  XML files and should not include binary formats embedded in a SVG wrapper.
+
+* The DPDK documentation contains some legacy images in PNG format. These will
+  be converted to SVG in time.
+
+* `Inkscape <inkscape.org>`_ is the recommended graphics editor for creating
+  the images. Use some of the older images in ``doc/guides/prog_guide/img/``
+  as a template, for example ``mbuf1.svg`` or ``ring-enqueue.svg``.
+
+* The SVG images should include a copyright notice, as an XML comment.
+
+* Images in the documentation should be formatted as follows:
+
+   * The image should be preceded by a label in the format
+     ``.. _figure_XXXX:`` with a leading underscore and where ``XXXX`` is a
+     unique descriptive name.
+
+   * Images should be included using the ``.. figure::`` directive and the
+     file type should be set to ``*`` (not ``.svg``). This allows the format
+     of the image to be changed if required.
+
+   * Images must have a caption as part of the ``.. figure::`` directive.
+
+* Here is an example of the previous three guidelines::
+
+     .. _figure_mempool:
+
+     .. figure:: img/mempool.*
+
+        A mempool in memory with its associated ring.
+
+.. _mock_label:
+
+* Images can then be linked to using the ``:numref:`` directive::
+
+     The mempool layout is shown in :numref:`figure_mempool`.
+
+  This would be rendered as: *The mempool layout is shown in* :ref:`Fig 6.3
+  <mock_label>`.
+
+  **Note**: The ``:numref:`` directive requires Sphinx 1.3.1 or later. With
+  earlier versions it will still be rendered as a link but won't have an
+  automatically generated number.
+
+* The caption of the image can be generated, with a link, using the ``:ref:``
+  directive::
+
+     :ref:`figure_mempool`
+
+  This would be rendered as: *A mempool in memory with its associated ring.*
+
+Tables
+~~~~~~
+
+* RST tables should be used sparingly. They are hard to format and to edit,
+  they are often rendered incorrectly in PDF format, and the same information
+  can usually be shown just as clearly with a list.
+
+* Tables in the documentation should be formatted as follows:
+
+   * The table should be preceded by a label in the format
+     ``.. _table_XXXX:`` with a leading underscore and where ``XXXX`` is a
+     unique descriptive name.
+
+   * Tables should be included using the ``.. table::`` directive and must
+     have a caption.
+
+* Here is an example of the previous two guidelines::
+
+     .. _table_qos_pipes:
+
+     .. table:: Sample configuration for QOS pipes.
+
+        +----------+----------+----------+
+        | Header 1 | Header 2 | Header 3 |
+        |          |          |          |
+        +==========+==========+==========+
+        | Text     | Text     | Text     |
+        +----------+----------+----------+
+        | ...      | ...      | ...      |
+        +----------+----------+----------+
+
+* Tables can be linked to using the ``:numref:`` and ``:ref:`` directives, as
+  shown in the previous section for images. For example::
+
+     The QOS configuration is shown in :numref:`table_qos_pipes`.
+
+* Tables should not include merged cells since they are not supported by the
+  PDF renderer.
+
+
+.. _links:
+
+Hyperlinks
+~~~~~~~~~~
+
+* Links to external websites can be plain URLs. The following is rendered as
+  http://dpdk.org::
+
+     http://dpdk.org
+
+* They can contain alternative text. The following is rendered as
+  `Check out DPDK <http://dpdk.org>`_::
+
+     `Check out DPDK <http://dpdk.org>`_
+
+* An internal link can be generated by placing labels in the document with the
+  format ``.. _label_name``.
+
+* The following links to the top of this section: :ref:`links`::
+
+     .. _links:
+
+     Hyperlinks
+     ~~~~~~~~~~
+
+     * The following links to the top of this section: :ref:`links`:
+
+.. Note::
+
+   The label must have a leading underscore but the reference to it must omit
+   it. This is a frequent cause of errors and warnings.
+
+* The use of a label is preferred since it works across files and will still
+  work if the header text changes.
+
+
+.. _doxygen_guidelines:
+
+Doxygen Guidelines
+------------------
+
+The DPDK API is documented using Doxygen comment annotations in the header
+files. Doxygen is a very powerful tool, it is extremely configurable and with
+a little effort can be used to create expressive documents. See the `Doxygen
+website <http://www.stack.nl/~dimitri/doxygen/>`_ for full details on how to
+use it.
+
+The following are some guidelines for use of Doxygen in the DPDK API
+documentation:
+
+* New libraries that are documented with Doxygen should be added to the
+  Doxygen configuration file: ``doc/api/doxy-api.conf``. It is only required
+  to add the directory that contains the files. It isn't necessary to
+  explicitly name each file since the configuration matches all ``rte_*.h``
+  files in the directory.
+
+* Use proper capitalization and punctuation in the Doxygen comments since they
+  will become sentences in the documentation. This in particular applies to
+  single line comments, which is the case the is most often forgotten.
+
+* Use ``@`` style Doxygen commands instead of ``\`` style commands.
+
+* Add a general description of each library at the head of the main header
+  files:
+
+  .. code-block:: c
+
+      /**
+       * @file
+       * RTE Mempool.
+       *
+       * A memory pool is an allocator of fixed-size object. It is
+       * identified by its name, and uses a ring to store free objects.
+       * ...
+       */
+
+* Document the purpose of a function, the parameters used and the return
+  value:
+
+  .. code-block:: c
+
+     /**
+      * Attach a new Ethernet device specified by arguments.
+      *
+      * @param devargs
+      *  A pointer to a strings array describing the new device
+      *  to be attached. The strings should be a pci address like
+      *  `0000:01:00.0` or **virtual** device name like `eth_pcap0`.
+      * @param port_id
+      *  A pointer to a port identifier actually attached.
+      *
+      * @return
+      *  0 on success and port_id is filled, negative on error.
+      */
+     int rte_eth_dev_attach(const char *devargs, uint8_t *port_id);
+
+* Doxygen supports Markdown style syntax such as bold, italics, fixed width
+  text and lists. For example the second line in the ``devargs`` parameter in
+  the previous example will be rendered as:
+
+     The strings should be a pci address like ``0000:01:00.0`` or **virtual**
+     device name like ``eth_pcap0``.
+
+* Use ``-`` instead of ``*`` for lists within the Doxygen comment since the
+  latter can get confused with the comment delimiter.
+
+* Add an empty line between the function description, the ``@params`` and
+  ``@return`` for readability.
+
+* Place the ``@params`` description on separate line and indent it by 2
+  spaces. (It would be better to use no indentation since this is more common
+  and also because checkpatch complains about leading whitespace in
+  comments. However this is the convention used in the existing DPDK code.)
+
+* Documented functions can be linked to simply by adding ``()`` to the
+  function name:
+
+  .. code-block:: c
+
+      /**
+       * The functions exported by the application Ethernet API to setup
+       * a device designated by its port identifier must be invoked in
+       * the following order:
+       *     - rte_eth_dev_configure()
+       *     - rte_eth_tx_queue_setup()
+       *     - rte_eth_rx_queue_setup()
+       *     - rte_eth_dev_start()
+       */
+
+  In the API documentation the functions will be rendered as links, see the
+  `online section of the rte_ethdev.h docs
+  <http://dpdk.org/doc/api/rte__ethdev_8h.html>`_ that contains the above
+  text.
+
+* The ``@see`` keyword can be used to create a *see also* link to another file
+  or library. This directive should be placed on one line at the bottom of the
+  documentation section.
+
+  .. code-block:: c
+
+     /**
+      * ...
+      *
+      * Some text that references mempools.
+      *
+      * @see eal_memzone.c
+      */
+
+* Doxygen supports two types of comments for documenting variables, constants
+  and members: prefix and postfix:
+
+  .. code-block:: c
+
+     /** This is a prefix comment. */
+     #define RTE_FOO_ERROR  0x023.
+
+     #define RTE_BAR_ERROR  0x024. /**< This is a postfix comment. */
+
+* Postfix comments are preferred for struct members and constants if they can
+  be documented in the same way:
+
+  .. code-block:: c
+
+     struct rte_eth_stats {
+         uint64_t ipackets; /**< Total number of received packets. */
+         uint64_t opackets; /**< Total number of transmitted packets.*/
+         uint64_t ibytes;   /**< Total number of received bytes. */
+         uint64_t obytes;   /**< Total number of transmitted bytes. */
+         uint64_t imissed;  /**< Total of RX missed packets. */
+         uint64_t ibadcrc;  /**< Total of RX packets with CRC error. */
+         uint64_t ibadlen;  /**< Total of RX packets with bad length. */
+     }
+
+  Note: postfix comments should be aligned with spaces not tabs in accordance
+  with the :ref:`coding_style`.
+
+* If a single comment type can't be used, due to line length limitations then
+  prefix comments should be preferred. For example this section of the code
+  contains prefix comments, postfix comments on the same line and postfix
+  comments on a separate line:
+
+  .. code-block:: c
+
+     /** Number of elements in the elt_pa array. */
+     uint32_t    pg_num __rte_cache_aligned;
+     uint32_t    pg_shift;     /**< LOG2 of the physical pages. */
+     uintptr_t   pg_mask;      /**< Physical page mask value. */
+     uintptr_t   elt_va_start;
+     /**< Virtual address of the first mempool object. */
+     uintptr_t   elt_va_end;
+     /**< Virtual address of the <size + 1> mempool object. */
+     phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
+     /**< Array of physical page addresses for the mempool buffer. */
+
+  This doesn't have an effect on the rendered documentation but it is
+  confusing for the developer reading the code. It this case it would be
+  clearer to use prefix comments throughout:
+
+  .. code-block:: c
+
+     /** Number of elements in the elt_pa array. */
+     uint32_t    pg_num __rte_cache_aligned;
+     /** LOG2 of the physical pages. */
+     uint32_t    pg_shift;
+     /** Physical page mask value. */
+     uintptr_t   pg_mask;
+     /** Virtual address of the first mempool object. */
+     uintptr_t   elt_va_start;
+     /** Virtual address of the <size + 1> mempool object. */
+     uintptr_t   elt_va_end;
+     /** Array of physical page addresses for the mempool buffer. */
+     phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
+
+* Check for Doxygen warnings in new code by checking the API documentation
+  build::
+
+     make doc-api-html | grep "warning:"
+
+* Read the rendered section of the documentation that you have added for
+  correctness, clarity and consistency with the surrounding text.
+
+
+Patching the Documentation
+--------------------------
+
+One of the easiest ways to contribute to DPDK is to submit a patch to the
+documentation.
+
+Over time the documentation may contain information that is slightly out of
+date or that could be improved upon. Newcomers to the DPDK project often
+notice these issues as they work through the examples and how-to guides.
+
+Rather than emailing the development list, or even ignoring the issue, it is
+just as easy to submit a patch to fix it. The following instructions explain
+how to do that and since they are meant to encourage contributions they assume
+no development experience or prior exposure to the DPDK workflow.
+
+#. Install the documentation dependencies as shown above. As a minimum you
+   should install Sphinx::
+
+      # Ubuntu/Debian.
+      sudo apt-get -y install python-sphinx
+
+      # Red Hat/Fedora.
+      sudo yum     -y install python-sphinx
+
+   If you are going to patch the API docs you will need Doxygen. You can omit
+   TexLive and Inkscape for now.
+
+#. Install ``git`` as follows::
+
+      # Ubuntu/Debian.
+      sudo apt-get -y install git
+
+      # Red Hat/Fedora.
+      sudo yum     -y install git
+
+   If you have any problems, refer to the official `Git installation guide
+   <https://git-scm.com/book/en/v2/Getting-Started-Installing-Git>`_.
+
+#. Configure your ``.gitconfig`` file with your name and email address::
+
+      git config --global user.name "J. Smith"
+      git config --global user.email jsmith@example.com
+
+   If you wish you can also configure the default editor that is used to write
+   commit messages::
+
+      git config --global core.editor vi
+
+   See the `Git getting started guide
+   <https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup>`_ if
+   you have any issues.
+
+#. Clone the DPDK repository (this can take a minute or two)::
+
+      git clone http://dpdk.org/git/dpdk
+
+#. Change into the new ``dpdk`` directory and test if you have the required
+   dependencies to build the docs::
+
+      cd dpdk
+      make doc-guides-html
+
+   If you get warnings about missing utilities go back and work through
+   installing the dependencies again.
+
+   If you installed some of the other dependencies you can try the following,
+   but they aren't required::
+
+      # If you installed Doxygen:
+      make doc-api-html
+
+      # If you installed Inkscape and TexLive as well:
+      make doc
+
+   .. Note::
+
+      You can ignore a warning about upgrading Sphinx, that is optional. If
+      you are building the documentation on Mac OS you can ignore a warning
+      from ``sed``.
+
+#. Using your preferred editor make the changes to the file you want to fix or
+   improve. For example::
+
+      vi doc/guides/linux_gsg/quick_start.rst
+
+#. Once you have make the modifications you should see a change in the ``git
+   status``::
+
+      git status
+
+      On branch master
+      Your branch is up-to-date with 'origin/master'.
+      Changes not staged for commit:
+        (use "git add <file>..." to update what will be committed)
+        (use "git checkout -- <file>..." to discard changes)
+
+        modified:   doc/guides/linux_gsg/quick_start.rst
+
+
+#. You will be able to review your changes using ``git diff``:
+
+   .. code-block:: diff
+
+      git diff
+
+      diff --git a/quick_start.rst b/quick_start.rst
+      index b07fc87..7b49e1c 100644
+      --- a/doc/guides/linux_gsg/quick_start.rst
+      +++ b/doc/guides/linux_gsg/quick_start.rst
+      @@ -256,7 +256,7 @@ The following selection demonstrates the launch
+
+           Enter hex bitmask of cores to execute test app on
+           Example: to execute app on cores 0 to 7, enter 0xff
+      -    bitmaks: 0x01
+      +    bitmask: 0x01
+           Launching app
+           EAL: coremask set to 1
+           EAL: Detected lcore 0 on socket 0
+
+   Two other diff options that are useful when dealing with changes to
+   documentation are word and character diffs::
+
+      # View differences by word instead of lines:
+      git diff --color-words
+
+      # View differences by character:
+      git diff --color-words=.
+
+
+#. Rebuild the docs and fix any new warnings::
+
+      make doc-guides-html
+
+#. Open the output Html document and review your changes in the context of the
+   surrounding text. Use a Web browser like the following::
+
+      firefox build/doc/html/guides/linux_gsg/quick_start.html &
+
+#. If everything is okay you can commit your changes to your local repository
+   and generate a patch. The first step is to add the file(s) that you
+   modified::
+
+      git add doc/guides/linux_gsg/quick_start.rst
+
+#. Now commit the changes to the local repository. You must "sign" the commit
+   by using ``-s``. This will insert the name and email address that you
+   configured in your ``.gitconfig`` above::
+
+      git commit -s
+
+   This will drop you into the default, or configured, editor and you can
+   insert a message like the following::
+
+      doc: fix minor typo in linux getting started guide
+
+      Fixed a minor typo in the Linux Getting Started Guide.
+
+      Signed-off-by: J. Smith <jsmith@example.com>
+
+   The first line will be used as a subject line for an email so it should:
+
+   * start with ``doc:``
+   * be less than 50 characters
+   * be lowercase only
+   * and not end with a period/full stop
+
+   The body of the text should:
+
+   * describe the change
+   * be wrapped at 72 characters
+   * have proper punctuation and capitalization
+
+   The body of the message should generally be longer than the example above
+   and should explain the purpose of the change.
+
+#. You can now create and email a patch. This can be done in one step from git
+   but for beginners it is best done in two steps so that you can review the
+   patch. First generate the patch::
+
+      git format-patch -1
+
+   This will generate a patch like the following::
+
+      0001-doc-fix-minor-typo-in-linux-getting-started-guide.patch
+
+   If you have a large patch or set of patches you can also generate a cover
+   letter to explain the changes by adding the ``--cover-letter`` option.
+
+
+#. If you are happy that everything looks good you can sent the patch to the
+   DPDK ``dev`` mailing list::
+
+      git send-mail --to dev@dpdk.org 0001-doc-fix-minor-typo-etc.patch
+
+   If you have issues see the `git send-mail
+   <http://git-scm.com/docs/git-send-email>`_ section of the the Git
+   documentation.
+
+   If all goes well the patch will appear on the `DPDK dev mailing list
+   <http://dpdk.org/ml/listinfo/dev>`_ and in the `DPDK Patchwork
+   <http://dpdk.org/dev/patchwork/project/dpdk/list/>`_.
diff --git a/doc/guides/guidelines/index.rst b/doc/guides/guidelines/index.rst
index bfb9fa3..1050d99 100644
--- a/doc/guides/guidelines/index.rst
+++ b/doc/guides/guidelines/index.rst
@@ -8,3 +8,5 @@ Guidelines
     coding_style
     design
     versioning
+    documentation
+
-- 
1.8.1.4

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Thomas Monjalon]

2015-07-02 14:50, John McNamara:
> Added guidelines on the purpose and structure of the DPDK
> documentation, how to build it and guidelines for creating it.
> 
> Also added guidelines on how to format and submit a documentation patch.

Good idea to have guidelines for doc.
But I think the submission guidelines shouldn't be specific to doc.
Could you move it to a contributing.rst file?
Guidelines from the website could be moved there.

> +  In general developers do not have to update the Release Notes apart from
> +  adding ABI announcements.

Someone must update the release notes.
Why not doing it atomicly when introducing a new feature?

> +  The guideline documents record the DPDK guidelines on coding, design, ABI
> +  usage and documentation.
> +
> +  These should be changed to clarify or improve guidelines.

The guideline documents record community process, expectations and design
directions.

They can be extended, amended or discussed by submitting a patch and getting
community approval.

> +* Sphinx.

Sphinx (also called python-sphinx).

> +
> +* TexLive.

TexLive (at least TexLive-core, extra Latex support and extra fonts). 

> +   # Ubuntu/Debian.
> +
> +   sudo apt-get -y install texlive-full

lighter:
sudo apt-get -y install texlive-latex-extra texlive-fonts-extra texlive-fonts-recommended

> +   # Red Hat/Fedora, selective install.
> +   sudo yum -y install texlive
> +   sudo yum -y install texlive-latex
> +   sudo yum -y install texlive-collection-latex
> +   sudo yum -y install texlive-collection-latexrecommended
> +   sudo yum -y install texlive-collection-latexextra
> +   sudo yum -y install texlive-dejavu

simpler:
sudo yum -y install texlive-collection-latexextra, texlive-collection-fontsextra

> +       aspell --lang=en_US --check doc/guides/sample_app_ug/mydoc.rst

Good tip!
What about making it more visible? :)

> +* Use one sentence per line in a paragraph, i.e., put a newline character
> +  after each period/full stop.

What about adding this?
Only blank line will generate a newline.

I think breaking lines at end of sentence is more important than
wrapping at 80 char, because it will help to keep patches
readable.

> +* Use one line per paragraph.

Why this recommendation? I think it doesn't help.

> +* Avoid lines longer than 80 character in literal blocks since they can exceed
> +  the page width when converted to PDF documentation. If possible try to wrap
> +  the text at sensible locations. For example a long command line could be
> +  documented like this and still work if copied directly from the docs::
> +
> +     build/app/testpmd -c7 -n3 --vdev=eth_pcap0,iface=eth0     \
> +                               --vdev=eth_pcap1,iface=eth1     \
> +                               -- -i --nb-cores=2 --nb-ports=2 \
> +                                  --total-num-mbufs=2048

Yes. Maybe that "avoid" is not strong enough.

> +* RST tables should be used sparingly. They are hard to format and to edit,
> +  they are often rendered incorrectly in PDF format, and the same information
> +  can usually be shown just as clearly with a list.

... or with a definition list.

> +* The use of a label is preferred since it works across files and will still
> +  work if the header text changes.

Artificial labels are a bit ugly.
If a header change, there will be an error for the link, right?

> +Doxygen Guidelines
> +------------------

I think you should split your patch here and have a separate patch to move
the doxygen guidelines from the coding style doc.

> +Patching the Documentation
> +--------------------------
> +
> +One of the easiest ways to contribute to DPDK is to submit a patch to the
> +documentation.
> +
> +Over time the documentation may contain information that is slightly out of
> +date or that could be improved upon. Newcomers to the DPDK project often
> +notice these issues as they work through the examples and how-to guides.
> +
> +Rather than emailing the development list, or even ignoring the issue, it is
> +just as easy to submit a patch to fix it. The following instructions explain
> +how to do that and since they are meant to encourage contributions they assume
> +no development experience or prior exposure to the DPDK workflow.
> +
> +#. Install the documentation dependencies as shown above. As a minimum you
> +   should install Sphinx::
> +

Using a link to above section would ease future update or extension.

> +      # Ubuntu/Debian.
> +      sudo apt-get -y install python-sphinx
> +
> +      # Red Hat/Fedora.
> +      sudo yum     -y install python-sphinx
> +
> +   If you are going to patch the API docs you will need Doxygen. You can omit
> +   TexLive and Inkscape for now.
> +

>From this point, it could be a link to a starter section in a contributing doc.

> +#. Install ``git`` as follows::
[...]
> +#. Clone the DPDK repository (this can take a minute or two)::
[...]

>From this point, it is specific to doc.

> +      make doc-guides-html
> +
> +   If you get warnings about missing utilities go back and work through
> +   installing the dependencies again.
[...]
> +      You can ignore a warning about upgrading Sphinx, that is optional. If
> +      you are building the documentation on Mac OS you can ignore a warning
> +      from ``sed``.

Not aware of this warning. Could it be removed?

> +#. If everything is okay you can commit your changes to your local repository
> +   and generate a patch. The first step is to add the file(s) that you
> +   modified::
> +
> +      git add doc/guides/linux_gsg/quick_start.rst
> +
> +#. Now commit the changes to the local repository. You must "sign" the commit
> +   by using ``-s``. This will insert the name and email address that you
> +   configured in your ``.gitconfig`` above::
> +
> +      git commit -s

For a primer doc, "git commit -as" skip the "git add" step and would be OK.

> +      doc: fix minor typo in linux getting started guide
> +
> +      Fixed a minor typo in the Linux Getting Started Guide.

No need to repeat the title.
It would be more interesting to know why it is better after the patch.
In case of a typo, no comment is needed after the title.

>From this point, it is not specific to doc.

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Bruce Richardson]

On Thu, Jul 02, 2015 at 06:20:39PM +0200, Thomas Monjalon wrote:
> 2015-07-02 14:50, John McNamara:
> > +* Use one sentence per line in a paragraph, i.e., put a newline character
> > +  after each period/full stop.
> 
> What about adding this?
> Only blank line will generate a newline.
> 
> I think breaking lines at end of sentence is more important than
> wrapping at 80 char, because it will help to keep patches
> readable.
>
+1 to this. I believe that one sentence per line should be the default wrapping
policy and only wrap if lines are very, very long. The why I like this approach
is that changes tend to be sentence-based, and so having a sentence per line
makes for much cleaner diffs when updating - thereby making review easier.

/Bruce

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Iremonger, Bernard]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> Sent: Friday, July 3, 2015 10:54 AM
> To: Thomas Monjalon
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk
> documentation
> 
> On Thu, Jul 02, 2015 at 06:20:39PM +0200, Thomas Monjalon wrote:
> > 2015-07-02 14:50, John McNamara:
> > > +* Use one sentence per line in a paragraph, i.e., put a newline
> > > +character
> > > +  after each period/full stop.
> >
> > What about adding this?
> > Only blank line will generate a newline.
> >
> > I think breaking lines at end of sentence is more important than
> > wrapping at 80 char, because it will help to keep patches readable.
> >
> +1 to this. I believe that one sentence per line should be the default
> +wrapping
> policy and only wrap if lines are very, very long. The why I like this approach is
> that changes tend to be sentence-based, and so having a sentence per line
> makes for much cleaner diffs when updating - thereby making review easier.
> 
> /Bruce

Hi Bruce,

I think "very, very long" should be defined.
When I was working on the rst files previously  I wrapped sentences which were  greater than 130 characters.
I wrapped long sentences at punctuation points where possible, rather than at the character limit.

Regards,

Bernard.

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Bruce Richardson]

On Fri, Jul 03, 2015 at 11:05:16AM +0100, Iremonger, Bernard wrote:
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > Sent: Friday, July 3, 2015 10:54 AM
> > To: Thomas Monjalon
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk
> > documentation
> > 
> > On Thu, Jul 02, 2015 at 06:20:39PM +0200, Thomas Monjalon wrote:
> > > 2015-07-02 14:50, John McNamara:
> > > > +* Use one sentence per line in a paragraph, i.e., put a newline
> > > > +character
> > > > +  after each period/full stop.
> > >
> > > What about adding this?
> > > Only blank line will generate a newline.
> > >
> > > I think breaking lines at end of sentence is more important than
> > > wrapping at 80 char, because it will help to keep patches readable.
> > >
> > +1 to this. I believe that one sentence per line should be the default
> > +wrapping
> > policy and only wrap if lines are very, very long. The why I like this approach is
> > that changes tend to be sentence-based, and so having a sentence per line
> > makes for much cleaner diffs when updating - thereby making review easier.
> > 
> > /Bruce
> 
> Hi Bruce,
> 
> I think "very, very long" should be defined.
Obviously :-)

> When I was working on the rst files previously  I wrapped sentences which were  greater than 130 characters.
> I wrapped long sentences at punctuation points where possible, rather than at the character limit.
>
Agree. I would suggest wrapping at a suitable punctuation point between 100-120 chars is best.

/Bruce

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Mcnamara, John]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Thursday, July 2, 2015 5:21 PM
> To: Mcnamara, John
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk
> documentation
>
> Good idea to have guidelines for doc.
> But I think the submission guidelines shouldn't be specific to doc.
> Could you move it to a contributing.rst file?
> Guidelines from the website could be moved there.

Hi Thomas,

I've removed the doc contributing guidelines and will resubmit at a later stage reworked as a more general contribution guidelines based on the information on dpdk.org.

Other comments have been integrated in V2 apart from the one below.


> > +* The use of a label is preferred since it works across files and
> > +will still
> > +  work if the header text changes.
> 
> Artificial labels are a bit ugly.
> If a header change, there will be an error for the link, right?

Most RST directives are ugly. Labels have the advantage of being explicit, and from what I can see, are widely used. Here are the recommendations from the Sphinx guide:

    Using ref is advised over standard reStructuredText links to
    sections (like `Section title`_) because it works across
    files, when section headings are changed, and for all
    builders that support cross-references.

    http://sphinx-doc.org/markup/inline.html#ref-role

John.
-- 

Re: [dpdk-dev] [PATCH 2/3] doc: added guidelines on dpdk documentation

[Mcnamara, John]

> -----Original Message-----
> From: Mcnamara, John
> Sent: Thursday, July 2, 2015 2:51 PM
> To: dev@dpdk.org
> Cc: Mcnamara, John
> Subject: [PATCH 2/3] doc: added guidelines on dpdk documentation
> 
> diff --git a/doc/guides/guidelines/documentation.rst
> b/doc/guides/guidelines/documentation.rst
> new file mode 100644
> index 0000000..d3e5905
> --- /dev/null
> +++ b/doc/guides/guidelines/documentation.rst
> @@ -0,0 +1,1005 @@
> +g.. doc_guidelines:

Typo here. s/g//

[dpdk-dev] [PATCH 3/3] doc: moved doxygen section to the doc guidelines

[John McNamara]

Moved and refactored the Doxygen guidelines from the Coding Style doc
to the Documentation Guidelines doc. Replaced the existing section
with a link.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/guidelines/coding_style.rst | 126 ++-------------------------------
 1 file changed, 7 insertions(+), 119 deletions(-)

diff --git a/doc/guides/guidelines/coding_style.rst b/doc/guides/guidelines/coding_style.rst
index c27fef4..12315bb 100644
--- a/doc/guides/guidelines/coding_style.rst
+++ b/doc/guides/guidelines/coding_style.rst
@@ -1,5 +1,7 @@
-Coding Style
-============
+.. _coding_style:
+
+DPDK Coding Style
+=================
 
 Description
 -----------
@@ -687,123 +689,9 @@ Control Statements
 Doxygen Documentation
 ---------------------
 
-The API documentation is automatically generated in the DPDK framework.
+The API documentation is automatically generated in the DPDK framework using `Doxygen <http://www.stack.nl/~dimitri/doxygen/>`_.
 That is why all files that are part of the public API must be documented using Doxygen syntax.
 
 The public API comprises functions of DPDK that can be used by an external application that will use the SDK.
-Only the Doxygen syntax described in the coding rules (this document) should be used in the code.
-All the Doxygen features are described in the Doxygen manual online.
-
-Documenting a Function
-~~~~~~~~~~~~~~~~~~~~~~
-
-All public functions must be documented. The documentation is placed in the header file, above the declaration of the function.
-The definition of the function may be documented, but using standard comments (not in doxygen format).
-The following is an example of function documentation:
-
-.. code-block:: c
-
- /**
-  * Summary here; one sentence on one line (should not exceed 80 chars).
-  *
-  * A more detailed description goes here.
-  *
-  * A blank line forms a paragraph. There should be no trailing white-space
-  * anywhere.
-  *
-  * @param first
-  *   "@param" is a Doxygen directive to describe a function parameter. Like
-  *   some other directives, it takes a term/summary on the same line and a
-  *   description (this text) indented by 2 spaces on the next line. All
-  *   descriptive text should wrap at 80 chars, without going over.
-  *   Newlines are NOT supported within directives; if a newline would be
-  *   before this text, it would be appended to the general description above.
-  * @param second
-  *   There should be no newline between multiple directives (of the same
-  *   type).
-  *
-  * @return
-  *   "@return" is a different Doxygen directive to describe the return value
-  *   of a function, if there is any.
-  */
- int rte_foo(int first, int second)
-
-
-Documenting Files
-~~~~~~~~~~~~~~~~~
-
-Each public file may start with a comment describing what the file does. For example:
-
-.. code-block:: c
-
- /**
-  * @file
-  * This file describes the coding rules of RTE.
-  *
-  * It contains the coding rules of C code, ASM code, reStructured
-  * Text documentation, and of course how to use doxygen to document
-  * public API.
-  */
-
-
-Documenting Constants and Variables
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Examples:
-
-.. code-block:: c
-
- /**
-  * The definition of a funny TRUE.
-  */
- #define TRUE 0
-
- #define TRUE 1 /**< another way to document a macro */
-
- /**
-  * Frequency of the HPET counter in Hz
-  *
-  * @see rte_eal_hpet_init()
-  */
- extern uint64_t eal_hpet_resolution_hz;
-
-
-Documenting Structures
-~~~~~~~~~~~~~~~~~~~~~~
-
-Public structures should also be documented.
-The ``/**<`` sequence can be used to documented the fields of the structure, as shown in the following example:
-
-.. code-block:: c
-
- /**
-  * Structure describing a memzone, which is a contiguous portions of
-  * physical memory identified by a name.
-  */
- struct rte_memzone {
-
- #define MEMZONE_NAMESIZE 32
-   char name[MEMZONE_NAMESIZE]; /**< name of the memory zone */
-
-   phys_addr_t phys_addr;       /**< start physical address */
-   void *addr;                  /**< start virtual address */
-   uint64_t len;                /**< len of the memzone */
-
-   int socket_id;               /**< NUMA socket id */
- };
-
-
-See Also Sections
-~~~~~~~~~~~~~~~~~
-
-The @see keyword can be used to highlight a link to an existing function, file, or URL.
-This directive should be placed on one line, without anything else, at the bottom of the documentation header.
-
-.. code-block:: c
-
- /**
-  * (documentation of function, file, ...)
-  *
-  * @see rte_foo()
-  * @see eal_memzone.c
-  */
+Only the Doxygen syntax described in the :ref:`doxygen_guidelines` should be used in the code.
+Other Doxygen features are described in the Doxygen manual online.
-- 
1.8.1.4

[dpdk-dev] [PATCH v2 0/3] doc: added guidelines on dpdk documentation

[John McNamara]

This patchset:

* Adds guidelines on the purpose and structure of the DPDK documentation,
  how to build it and guidelines for creating it and adding to it.

* Moves and refactors the Doxygen guidelines from the Coding Style doc to
  the Documentation Guidelines doc.

As with the other guidelines the main idea is to document the status quo and
then modify/add to it over time.


V2:
* Incorporates mailing list comments.

* Removed doc patch contribution guide. Will submit separately
  as contribution guidelines.

V1:
* Initial version.



John McNamara (3):
  doc: set the default literal block format
  doc: added guidelines on dpdk documentation
  doc: moved doxygen section to the doc guidelines

 doc/guides/conf.py                      |   1 +
 doc/guides/guidelines/coding_style.rst  | 134 +-----
 doc/guides/guidelines/documentation.rst | 745 ++++++++++++++++++++++++++++++++
 doc/guides/guidelines/index.rst         |   2 +
 4 files changed, 754 insertions(+), 128 deletions(-)
 create mode 100644 doc/guides/guidelines/documentation.rst

-- 
1.8.1.4

[dpdk-dev] [PATCH v2 1/3] doc: set the default literal block format

[John McNamara]

Set the default literal block format for Sphinx docs
to 'none' instead of the implicit default of 'python'.

This means that default :: blocks won't have any
highlighting applied. Explicit highlighting via
the code-block:: directive is already available and
in use in the docs.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/conf.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/guides/conf.py b/doc/guides/conf.py
index e1edffd..b2290b4 100644
--- a/doc/guides/conf.py
+++ b/doc/guides/conf.py
@@ -38,6 +38,7 @@ from pygments.formatters.latex import LatexFormatter
 project = 'DPDK'
 
 html_show_copyright = False
+highlight_language = 'none'
 
 version = subprocess.check_output(['make', '-sRrC', '../../', 'showversion']).decode('utf-8')
 release = version
-- 
1.8.1.4

Re: [dpdk-dev] [PATCH v2 1/3] doc: set the default literal block format

[Bruce Richardson]

On Fri, Jul 10, 2015 at 04:45:19PM +0100, John McNamara wrote:
> Set the default literal block format for Sphinx docs
> to 'none' instead of the implicit default of 'python'.
> 
> This means that default :: blocks won't have any
> highlighting applied. Explicit highlighting via
> the code-block:: directive is already available and
> in use in the docs.
> 
> Signed-off-by: John McNamara <john.mcnamara@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>

[dpdk-dev] [PATCH v2 2/3] doc: added guidelines on dpdk documentation

[John McNamara]

Added guidelines on the purpose and structure of the DPDK
documentation, how to build it and guidelines for creating it.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/guidelines/documentation.rst | 579 ++++++++++++++++++++++++++++++++
 doc/guides/guidelines/index.rst         |   2 +
 2 files changed, 581 insertions(+)
 create mode 100644 doc/guides/guidelines/documentation.rst

diff --git a/doc/guides/guidelines/documentation.rst b/doc/guides/guidelines/documentation.rst
new file mode 100644
index 0000000..b47f028
--- /dev/null
+++ b/doc/guides/guidelines/documentation.rst
@@ -0,0 +1,579 @@
+.. doc_guidelines:
+
+DPDK Documentation Guidelines
+=============================
+
+This document outlines the guidelines for writing the DPDK Guides and API documentation in RST and Doxygen format.
+
+It also explains the structure of the DPDK documentation and shows how to build the Html and PDF versions of the documents.
+
+
+Structure of the Documentation
+------------------------------
+
+The DPDK source code repository contains input files to build the API documentation and User Guides.
+
+The main directories that contain files related to documentation are shown below::
+
+   lib
+   |-- librte_acl
+   |-- librte_cfgfile
+   |-- librte_cmdline
+   |-- librte_compat
+   |-- librte_eal
+   |   |-- ...
+   ...
+   doc
+   |-- api
+   +-- guides
+       |-- freebsd_gsg
+       |-- linux_gsg
+       |-- prog_guide
+       |-- sample_app_ug
+       |-- guidelines
+       |-- testpmd_app_ug
+       |-- rel_notes
+       |-- nics
+       |-- xen
+       |-- ...
+
+
+The API documentation is built from `Doxygen <http://www.stack.nl/~dimitri/doxygen/>`_ comments in the header files.
+These files are mainly in the ``lib/lib_rte_*`` directories although some of the Poll Mode Drivers in ``drivers/net``
+are also documented with Doxygen.
+
+The configuration files that are used to control the Doxygen output are in the ``doc/api`` directory.
+
+The user guides such as *The Programmers Guide* and the *FreeBSD* and *Linux Getting Started* Guides are generated
+from RST markup text files using the `Sphinx <http://sphinx-doc.org/index.html>`_ Documentation Generator.
+
+These files are included in the ``doc/guides/`` directory.
+The output is controlled by the ``doc/guides/conf.py`` file.
+
+
+Role of the Documentation
+-------------------------
+
+The following items outline the roles of the different parts of the documentation and when they need to be updated or
+added to by the developer.
+
+* **Release Notes**
+
+  The Release Notes document which features have been added in the current and previous releases of DPDK and highlight
+  any known issues.
+  The Releases Notes also contain notifications of features that will change ABI compatibility in the next major release.
+
+  Developers should update the Release Notes to add a short description of new or updated features.
+  Developers should also update the Release Notes to add ABI announcements if necessary,
+  (see :doc:`/guidelines/versioning` for details).
+
+* **API documentation**
+
+  The API documentation explains how to use the public DPDK functions.
+  The `API index page <http://dpdk.org/doc/api/>`_ shows the generated API documentation with related groups of functions.
+
+  The API documentation should be updated via Doxygen comments when new functions are added.
+
+* **Getting Started Guides**
+
+  The Getting Started Guides show how to install and configure DPDK and how to run DPDK based applications on different OSes.
+
+  A Getting Started Guide should be added when DPDK is ported to a new OS.
+
+* **The Programmers Guide**
+
+  The Programmers Guide explains how the API components of DPDK such as the EAL, Memzone, Rings and the Hash Library work.
+  It also explains how some higher level functionality such as Packet Distributor, Packet Framework and KNI work.
+  It also shows the build system and explains how to add applications.
+
+  The Programmers Guide should be expanded when new functionality is added to DPDK.
+
+* **App Guides**
+
+  The app guides document the DPDK applications in the ``app`` directory such as ``testpmd``.
+
+  The app guides should be updated if functionality is changed or added.
+
+* **Sample App Guides**
+
+  The sample app guides document the DPDK example applications in the examples directory.
+  Generally they demonstrate a major feature such as L2 or L3 Forwarding, Multi Process or Power Management.
+  They explain the purpose of the sample application, how to run it and step through some of the code to explain the
+  major functionality.
+
+  A new sample application should be accompanied by a new sample app guide.
+  The guide for the Skeleton Forwarding app is a good starting reference.
+
+* **Network Interface Controller Drivers**
+
+  The NIC Drivers document explains the features of the individual Poll Mode Drivers, such as software requirements,
+  configuration and initialization.
+
+  New documentation should be added for new Poll Mode Drivers.
+
+* **Guidelines**
+
+  The guideline documents record community process, expectations and design directions.
+
+  They can be extended, amended or discussed by submitting a patch and getting community approval.
+
+
+Building the Documentation
+--------------------------
+
+Dependencies
+~~~~~~~~~~~~
+
+
+The following dependencies must be installed to build the documentation:
+
+* Doxygen.
+
+* Sphinx (also called python-sphinx).
+
+* TexLive (at least TexLive-core, extra Latex support and extra fonts).
+
+* Inkscape.
+
+`Doxygen`_ generates documentation from commented source code.
+It can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install doxygen
+
+   # Red Hat/Fedora.
+   sudo yum     -y install doxygen
+
+`Sphinx`_ is a Python documentation tool for converting RST files to Html or to PDF (via LaTeX).
+It can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install python-sphinx
+
+   # Red Hat/Fedora.
+   sudo yum     -y install python-sphinx
+
+   # Or, on any system with Python installed.
+   sudo easy_install -U sphinx
+
+For further information on getting started with Sphinx see the `Sphinx Tutorial <http://sphinx-doc.org/tutorial.html>`_.
+
+.. Note::
+
+   To get full support for Figure and Table numbering it is best to install Sphinx 1.3.1 or later.
+
+
+`Inkscape`_ is a vector based graphics program which is used to create SVG images and also to convert SVG images to PDF images.
+It can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install inkscape
+
+   # Red Hat/Fedora.
+   sudo yum     -y install inkscape
+
+`TexLive <http://www.tug.org/texlive/>`_ is an installation package for Tex/LaTeX.
+It is used to generate the PDF versions of the documentation.
+The main required packages can be installed as follows:
+
+.. code-block:: console
+
+   # Ubuntu/Debian.
+   sudo apt-get -y install texlive-latex-extra texlive-fonts-extra \
+                           texlive-fonts-recommended
+
+
+   # Red Hat/Fedora, selective install.
+   sudo yum     -y install texlive-collection-latexextra \
+                           texlive-collection-fontsextra
+
+
+Build commands
+~~~~~~~~~~~~~~
+
+The documentation is built using the standard DPDK build system.
+Some examples are shown below:
+
+* Generate all the documentation targets::
+
+     make doc
+
+* Generate the Doxygen API documentation in Html::
+
+     make doc-api-html
+
+* Generate the guides documentation in Html::
+
+     make doc-guides-html
+
+* Generate the guides documentation in Pdf::
+
+     make doc-guides-pdf
+
+The output of these commands is generated in the ``build`` directory::
+
+   build/doc
+         |-- html
+         |   |-- api
+         |   +-- guides
+         |
+         +-- pdf
+             +-- guides
+
+
+.. Note::
+
+   Make sure to fix any Sphinx or Doxygen warnings when adding or updating documentation.
+
+The documentation output files can be removed as follows::
+
+   make doc-clean
+
+
+Document Guidelines
+-------------------
+
+Here are some guidelines in relation to the style of the documentation:
+
+* Document the obvious as well as the obscure since it won't always be obvious to the reader.
+  For example an instruction like "Set up 64 2MB Hugepages" is better when followed by a sample commandline or a link to
+  the appropriate section of the documentation.
+
+* Use American English spellings throughout.
+  This can be checked using the ``aspell`` utility::
+
+       aspell --lang=en_US --check doc/guides/sample_app_ug/mydoc.rst
+
+
+RST Guidelines
+--------------
+
+The RST (reStructuredText) format is a plain text markup format that can be converted to Html, PDF or other formats.
+It is most closely associated with Python but it can be used to document any language.
+It is used in DPDK to document everything apart from the API.
+
+The Sphinx documentation contains a very useful `RST Primer <http://sphinx-doc.org/rest.html#rst-primer>`_ which is a
+good place to learn the minimal set of syntax required to format a document.
+
+The official `reStructuredText <http://docutils.sourceforge.net/rst.html>`_ website contains the specification for the
+RST format and also examples of how to use it.
+However, for most developers the RST Primer is a better resource.
+
+The most common guidelines for writing RST text are detailed in the
+`Documenting Python <https://docs.python.org/devguide/documenting.html>`_ guidelines.
+The additional guidelines below reiterate or expand upon those guidelines.
+
+
+Line Length
+~~~~~~~~~~~
+
+* The recommended style for the DPDK documentation is to put sentences on separate lines.
+  This allows for easier reviewing of patches.
+  Multiple sentences which are not separated by a blank line are joined automatically into paragraphs, for example::
+
+     Here is an example sentence.
+     Long sentences over the limit shown below can be wrapped onto
+     a new line.
+     These three sentences will be joined into the same paragraph.
+
+     This is a new paragraph, since it is separated from the
+     previous paragraph by a blank line.
+
+  This would be rendered as follows:
+
+     *Here is an example sentence.
+     Long sentences over the limit shown below can be wrapped onto
+     a new line.
+     These three sentences will be joined into the same paragraph.*
+
+     *This is a new paragraph, since it is separated from the
+     previous paragraph by a blank line.*
+
+
+* Long sentences should be wrapped at 120 characters +/- 10 characters. They should be wrapped at words.
+
+* Lines in literal blocks must by less than 80 characters since they aren't wrapped by the document formatters
+  and can exceed the page width in PDF documents.
+
+
+Whitespace
+~~~~~~~~~~
+
+* Standard RST indentation is 3 spaces.
+  Code can be indented 4 spaces, especially if it is copied from source files.
+
+* No tabs.
+  Convert tabs in embedded code to 4 or 8 spaces.
+
+* No trailing whitespace.
+
+* Add 2 blank lines before each section header.
+
+* Add 1 blank line after each section header.
+
+* Add 1 blank line between each line of a list.
+
+
+Section Headers
+~~~~~~~~~~~~~~~
+
+* Section headers should use the use the following underline formats::
+
+   Level 1 Heading
+   ===============
+
+
+   Level 2 Heading
+   ---------------
+
+
+   Level 3 Heading
+   ~~~~~~~~~~~~~~~
+
+
+   Level 4 Heading
+   ^^^^^^^^^^^^^^^
+
+
+* Level 4 headings should be used sparingly.
+
+* The underlines should match the length of the text.
+
+* In general, the heading should be less than 80 characters, for conciseness.
+
+* As noted above:
+
+   * Add 2 blank lines before each section header.
+
+   * Add 1 blank line after each section header.
+
+
+Lists
+~~~~~
+
+* Bullet lists should be formatted with a leading ``*`` as follows::
+
+     * Item one.
+
+     * Item two is a long line that is wrapped and then indented to match
+       the start of the previous line.
+
+     * One space character between the bullet and the text is preferred.
+
+* Numbered lists can be formatted with a leading number but the preference is to use ``#.`` which will give automatic numbering.
+  This is more convenient when adding or removing items::
+
+     #. Item one.
+
+     #. Item two is a long line that is wrapped and then indented
+        to match the start of the e first line.
+
+     #. Item two is a long line that is wrapped and then indented to match
+        the start of the previous line.
+
+* Definition lists can be written with or without a bullet::
+
+     * Item one.
+
+       Some text about item one.
+
+     * Item two.
+
+       Some text about item two.
+
+* All lists, and sub-lists, must be separated from the preceding text by a blank line.
+  This is a syntax requirement.
+
+* All list items should be separated by a blank line for readability.
+
+
+Code and Literal block sections
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* Inline text that is required to be rendered with a fixed width font should be enclosed in backquotes like this:
+  \`\`text\`\`, so that it appears like this: ``text``.
+
+* Fixed width, literal blocks of texts should be indented at least 3 spaces and prefixed with ``::`` like this::
+
+     Here is some fixed width text::
+
+        0x0001 0x0001 0x00FF 0x00FF
+
+* It is also possible to specify an encoding for a literal block using the ``.. code-block::`` directive so that syntax
+  highlighting can be applied.
+  Examples of supported highlighting are::
+
+     .. code-block:: console
+     .. code-block:: c
+     .. code-block:: python
+     .. code-block:: diff
+     .. code-block:: none
+
+  That can be applied as follows::
+
+      .. code-block:: c
+
+         #include<stdio.h>
+
+         int main() {
+
+            printf("Hello World\n");
+
+            return 0;
+         }
+
+  Which would be rendered as:
+
+  .. code-block:: c
+
+      #include<stdio.h>
+
+      int main() {
+
+         printf("Hello World\n");
+
+         return 0;
+      }
+
+
+* The default encoding for a literal block using the simplified ``::``
+  directive is ``none``.
+
+* Lines in literal blocks must be less than 80 characters since they can exceed the page width when converted to PDF documentation.
+  For long literal lines that exceed that limit try to wrap the text at sensible locations.
+  For example a long command line could be documented like this and still work if copied directly from the docs::
+
+     build/app/testpmd -c7 -n3 --vdev=eth_pcap0,iface=eth0     \
+                               --vdev=eth_pcap1,iface=eth1     \
+                               -- -i --nb-cores=2 --nb-ports=2 \
+                                  --total-num-mbufs=2048
+
+* Long lines that cannot be wrapped, such as application output, should be truncated to be less than 80 characters.
+
+
+Images
+~~~~~~
+
+* All images should be in SVG scalar graphics format.
+  They should be true SVG XML files and should not include binary formats embedded in a SVG wrapper.
+
+* The DPDK documentation contains some legacy images in PNG format.
+  These will be converted to SVG in time.
+
+* `Inkscape <inkscape.org>`_ is the recommended graphics editor for creating the images.
+  Use some of the older images in ``doc/guides/prog_guide/img/`` as a template, for example ``mbuf1.svg``
+  or ``ring-enqueue.svg``.
+
+* The SVG images should include a copyright notice, as an XML comment.
+
+* Images in the documentation should be formatted as follows:
+
+   * The image should be preceded by a label in the format ``.. _figure_XXXX:`` with a leading underscore and
+     where ``XXXX`` is a unique descriptive name.
+
+   * Images should be included using the ``.. figure::`` directive and the file type should be set to ``*`` (not ``.svg``).
+     This allows the format of the image to be changed if required, without updating the documentation.
+
+   * Images must have a caption as part of the ``.. figure::`` directive.
+
+* Here is an example of the previous three guidelines::
+
+     .. _figure_mempool:
+
+     .. figure:: img/mempool.*
+
+        A mempool in memory with its associated ring.
+
+.. _mock_label:
+
+* Images can then be linked to using the ``:numref:`` directive::
+
+     The mempool layout is shown in :numref:`figure_mempool`.
+
+  This would be rendered as: *The mempool layout is shown in* :ref:`Fig 6.3 <mock_label>`.
+
+  **Note**: The ``:numref:`` directive requires Sphinx 1.3.1 or later.
+  With earlier versions it will still be rendered as a link but won't have an automatically generated number.
+
+* The caption of the image can be generated, with a link, using the ``:ref:`` directive::
+
+     :ref:`figure_mempool`
+
+  This would be rendered as: *A mempool in memory with its associated ring.*
+
+Tables
+~~~~~~
+
+* RST tables should be used sparingly.
+  They are hard to format and to edit, they are often rendered incorrectly in PDF format, and the same information
+  can usually be shown just as clearly with a definition or bullet list.
+
+* Tables in the documentation should be formatted as follows:
+
+   * The table should be preceded by a label in the format ``.. _table_XXXX:`` with a leading underscore and where
+     ``XXXX`` is a unique descriptive name.
+
+   * Tables should be included using the ``.. table::`` directive and must have a caption.
+
+* Here is an example of the previous two guidelines::
+
+     .. _table_qos_pipes:
+
+     .. table:: Sample configuration for QOS pipes.
+
+        +----------+----------+----------+
+        | Header 1 | Header 2 | Header 3 |
+        |          |          |          |
+        +==========+==========+==========+
+        | Text     | Text     | Text     |
+        +----------+----------+----------+
+        | ...      | ...      | ...      |
+        +----------+----------+----------+
+
+* Tables can be linked to using the ``:numref:`` and ``:ref:`` directives, as shown in the previous section for images.
+  For example::
+
+     The QOS configuration is shown in :numref:`table_qos_pipes`.
+
+* Tables should not include merged cells since they are not supported by the PDF renderer.
+
+
+.. _links:
+
+Hyperlinks
+~~~~~~~~~~
+
+* Links to external websites can be plain URLs.
+  The following is rendered as http://dpdk.org::
+
+     http://dpdk.org
+
+* They can contain alternative text.
+  The following is rendered as `Check out DPDK <http://dpdk.org>`_::
+
+     `Check out DPDK <http://dpdk.org>`_
+
+* An internal link can be generated by placing labels in the document with the format ``.. _label_name``.
+
+* The following links to the top of this section: :ref:`links`::
+
+     .. _links:
+
+     Hyperlinks
+     ~~~~~~~~~~
+
+     * The following links to the top of this section: :ref:`links`:
+
+.. Note::
+
+   The label must have a leading underscore but the reference to it must omit it.
+   This is a frequent cause of errors and warnings.
+
+* The use of a label is preferred since it works across files and will still work if the header text changes.
+
diff --git a/doc/guides/guidelines/index.rst b/doc/guides/guidelines/index.rst
index bfb9fa3..1050d99 100644
--- a/doc/guides/guidelines/index.rst
+++ b/doc/guides/guidelines/index.rst
@@ -8,3 +8,5 @@ Guidelines
     coding_style
     design
     versioning
+    documentation
+
-- 
1.8.1.4

Re: [dpdk-dev] [PATCH v2 2/3] doc: added guidelines on dpdk documentation

[Bruce Richardson]

On Fri, Jul 10, 2015 at 04:45:20PM +0100, John McNamara wrote:
> Added guidelines on the purpose and structure of the DPDK
> documentation, how to build it and guidelines for creating it.
> 
> Signed-off-by: John McNamara <john.mcnamara@intel.com>

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

with one minor error highlighted below.

> ---
>  doc/guides/guidelines/documentation.rst | 579 ++++++++++++++++++++++++++++++++
>  doc/guides/guidelines/index.rst         |   2 +
>  2 files changed, 581 insertions(+)
>  create mode 100644 doc/guides/guidelines/documentation.rst
> 
> diff --git a/doc/guides/guidelines/documentation.rst b/doc/guides/guidelines/documentation.rst
> new file mode 100644
> index 0000000..b47f028
> --- /dev/null
> +++ b/doc/guides/guidelines/documentation.rst
> @@ -0,0 +1,579 @@
> +.. doc_guidelines:
> +
> +DPDK Documentation Guidelines
> +=============================
> +
<SNIP>
> +The API documentation is built from `Doxygen <http://www.stack.nl/~dimitri/doxygen/>`_ comments in the header files.
> +These files are mainly in the ``lib/lib_rte_*`` directories although some of the Poll Mode Drivers in ``drivers/net``

Minor nit - No "_" between lib and rte in the library names.

[dpdk-dev] [PATCH v2 3/3] doc: moved doxygen section to the doc guidelines

[John McNamara]

Moved and refactored the Doxygen guidelines from the Coding Style doc
to the Documentation Guidelines doc. Replaced the existing Doxygen
references with links.

Signed-off-by: John McNamara <john.mcnamara@intel.com>
---
 doc/guides/guidelines/coding_style.rst  | 134 ++------------------------
 doc/guides/guidelines/documentation.rst | 166 ++++++++++++++++++++++++++++++++
 2 files changed, 172 insertions(+), 128 deletions(-)

diff --git a/doc/guides/guidelines/coding_style.rst b/doc/guides/guidelines/coding_style.rst
index c27fef4..22f26dd 100644
--- a/doc/guides/guidelines/coding_style.rst
+++ b/doc/guides/guidelines/coding_style.rst
@@ -1,5 +1,7 @@
-Coding Style
-============
+.. _coding_style:
+
+DPDK Coding Style
+=================
 
 Description
 -----------
@@ -31,7 +33,7 @@ Usual Comments
 ~~~~~~~~~~~~~~
 
 These comments should be used in normal cases.
-To document a public API, a doxygen-like format must be used: refer to Doxygen Documentation.
+To document a public API, a doxygen-like format must be used: refer to :ref:`doxygen_guidelines`.
 
 .. code-block:: c
 
@@ -491,7 +493,7 @@ Prototypes
 * Function prototypes should be listed in a logical order, preferably alphabetical unless there is a compelling reason to use a different ordering.
 * Functions that are used locally in more than one module go into a separate header file, for example, "extern.h".
 * Do not use the ``__P`` macro.
-* Functions that are part of an external API should be documented using Doxygen-like comments above declarations. See the Doxgen documentation topic for details.
+* Functions that are part of an external API should be documented using Doxygen-like comments above declarations. See :ref:`doxygen_guidelines` for details.
 * Functions that are part of the external API must have an ``rte_`` prefix on the function name.
 * Do not use uppercase letters - either in the form of ALL_UPPERCASE, or CamelCase - in function names. Lower-case letters and underscores only.
 * When prototyping functions, associate names with parameter types, for example:
@@ -683,127 +685,3 @@ Control Statements
                  usage();
                  /* NOTREACHED */
          }
-
-Doxygen Documentation
----------------------
-
-The API documentation is automatically generated in the DPDK framework.
-That is why all files that are part of the public API must be documented using Doxygen syntax.
-
-The public API comprises functions of DPDK that can be used by an external application that will use the SDK.
-Only the Doxygen syntax described in the coding rules (this document) should be used in the code.
-All the Doxygen features are described in the Doxygen manual online.
-
-Documenting a Function
-~~~~~~~~~~~~~~~~~~~~~~
-
-All public functions must be documented. The documentation is placed in the header file, above the declaration of the function.
-The definition of the function may be documented, but using standard comments (not in doxygen format).
-The following is an example of function documentation:
-
-.. code-block:: c
-
- /**
-  * Summary here; one sentence on one line (should not exceed 80 chars).
-  *
-  * A more detailed description goes here.
-  *
-  * A blank line forms a paragraph. There should be no trailing white-space
-  * anywhere.
-  *
-  * @param first
-  *   "@param" is a Doxygen directive to describe a function parameter. Like
-  *   some other directives, it takes a term/summary on the same line and a
-  *   description (this text) indented by 2 spaces on the next line. All
-  *   descriptive text should wrap at 80 chars, without going over.
-  *   Newlines are NOT supported within directives; if a newline would be
-  *   before this text, it would be appended to the general description above.
-  * @param second
-  *   There should be no newline between multiple directives (of the same
-  *   type).
-  *
-  * @return
-  *   "@return" is a different Doxygen directive to describe the return value
-  *   of a function, if there is any.
-  */
- int rte_foo(int first, int second)
-
-
-Documenting Files
-~~~~~~~~~~~~~~~~~
-
-Each public file may start with a comment describing what the file does. For example:
-
-.. code-block:: c
-
- /**
-  * @file
-  * This file describes the coding rules of RTE.
-  *
-  * It contains the coding rules of C code, ASM code, reStructured
-  * Text documentation, and of course how to use doxygen to document
-  * public API.
-  */
-
-
-Documenting Constants and Variables
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Examples:
-
-.. code-block:: c
-
- /**
-  * The definition of a funny TRUE.
-  */
- #define TRUE 0
-
- #define TRUE 1 /**< another way to document a macro */
-
- /**
-  * Frequency of the HPET counter in Hz
-  *
-  * @see rte_eal_hpet_init()
-  */
- extern uint64_t eal_hpet_resolution_hz;
-
-
-Documenting Structures
-~~~~~~~~~~~~~~~~~~~~~~
-
-Public structures should also be documented.
-The ``/**<`` sequence can be used to documented the fields of the structure, as shown in the following example:
-
-.. code-block:: c
-
- /**
-  * Structure describing a memzone, which is a contiguous portions of
-  * physical memory identified by a name.
-  */
- struct rte_memzone {
-
- #define MEMZONE_NAMESIZE 32
-   char name[MEMZONE_NAMESIZE]; /**< name of the memory zone */
-
-   phys_addr_t phys_addr;       /**< start physical address */
-   void *addr;                  /**< start virtual address */
-   uint64_t len;                /**< len of the memzone */
-
-   int socket_id;               /**< NUMA socket id */
- };
-
-
-See Also Sections
-~~~~~~~~~~~~~~~~~
-
-The @see keyword can be used to highlight a link to an existing function, file, or URL.
-This directive should be placed on one line, without anything else, at the bottom of the documentation header.
-
-.. code-block:: c
-
- /**
-  * (documentation of function, file, ...)
-  *
-  * @see rte_foo()
-  * @see eal_memzone.c
-  */
diff --git a/doc/guides/guidelines/documentation.rst b/doc/guides/guidelines/documentation.rst
index b47f028..3ef334b 100644
--- a/doc/guides/guidelines/documentation.rst
+++ b/doc/guides/guidelines/documentation.rst
@@ -577,3 +577,169 @@ Hyperlinks
 
 * The use of a label is preferred since it works across files and will still work if the header text changes.
 
+
+.. _doxygen_guidelines:
+
+Doxygen Guidelines
+------------------
+
+The DPDK API is documented using Doxygen comment annotations in the header files.
+Doxygen is a very powerful tool, it is extremely configurable and with a little effort can be used to create expressive documents.
+See the `Doxygen website <http://www.stack.nl/~dimitri/doxygen/>`_ for full details on how to use it.
+
+The following are some guidelines for use of Doxygen in the DPDK API documentation:
+
+* New libraries that are documented with Doxygen should be added to the Doxygen configuration file: ``doc/api/doxy-api.conf``.
+  It is only required to add the directory that contains the files.
+  It isn't necessary to explicitly name each file since the configuration matches all ``rte_*.h`` files in the directory.
+
+* Use proper capitalization and punctuation in the Doxygen comments since they will become sentences in the documentation.
+  This in particular applies to single line comments, which is the case the is most often forgotten.
+
+* Use ``@`` style Doxygen commands instead of ``\`` style commands.
+
+* Add a general description of each library at the head of the main header files:
+
+  .. code-block:: c
+
+      /**
+       * @file
+       * RTE Mempool.
+       *
+       * A memory pool is an allocator of fixed-size object. It is
+       * identified by its name, and uses a ring to store free objects.
+       * ...
+       */
+
+* Document the purpose of a function, the parameters used and the return
+  value:
+
+  .. code-block:: c
+
+     /**
+      * Attach a new Ethernet device specified by arguments.
+      *
+      * @param devargs
+      *  A pointer to a strings array describing the new device
+      *  to be attached. The strings should be a pci address like
+      *  `0000:01:00.0` or **virtual** device name like `eth_pcap0`.
+      * @param port_id
+      *  A pointer to a port identifier actually attached.
+      *
+      * @return
+      *  0 on success and port_id is filled, negative on error.
+      */
+     int rte_eth_dev_attach(const char *devargs, uint8_t *port_id);
+
+* Doxygen supports Markdown style syntax such as bold, italics, fixed width text and lists.
+  For example the second line in the ``devargs`` parameter in the previous example will be rendered as:
+
+     The strings should be a pci address like ``0000:01:00.0`` or **virtual** device name like ``eth_pcap0``.
+
+* Use ``-`` instead of ``*`` for lists within the Doxygen comment since the latter can get confused with the comment delimiter.
+
+* Add an empty line between the function description, the ``@params`` and ``@return`` for readability.
+
+* Place the ``@params`` description on separate line and indent it by 2 spaces.
+  (It would be better to use no indentation since this is more common and also because checkpatch complains about leading
+  whitespace in comments.
+  However this is the convention used in the existing DPDK code.)
+
+* Documented functions can be linked to simply by adding ``()`` to the function name:
+
+  .. code-block:: c
+
+      /**
+       * The functions exported by the application Ethernet API to setup
+       * a device designated by its port identifier must be invoked in
+       * the following order:
+       *     - rte_eth_dev_configure()
+       *     - rte_eth_tx_queue_setup()
+       *     - rte_eth_rx_queue_setup()
+       *     - rte_eth_dev_start()
+       */
+
+  In the API documentation the functions will be rendered as links, see the
+  `online section of the rte_ethdev.h docs <http://dpdk.org/doc/api/rte__ethdev_8h.html>`_ that contains the above text.
+
+* The ``@see`` keyword can be used to create a *see also* link to another file or library.
+  This directive should be placed on one line at the bottom of the documentation section.
+
+  .. code-block:: c
+
+     /**
+      * ...
+      *
+      * Some text that references mempools.
+      *
+      * @see eal_memzone.c
+      */
+
+* Doxygen supports two types of comments for documenting variables, constants and members: prefix and postfix:
+
+  .. code-block:: c
+
+     /** This is a prefix comment. */
+     #define RTE_FOO_ERROR  0x023.
+
+     #define RTE_BAR_ERROR  0x024. /**< This is a postfix comment. */
+
+* Postfix comments are preferred for struct members and constants if they can be documented in the same way:
+
+  .. code-block:: c
+
+     struct rte_eth_stats {
+         uint64_t ipackets; /**< Total number of received packets. */
+         uint64_t opackets; /**< Total number of transmitted packets.*/
+         uint64_t ibytes;   /**< Total number of received bytes. */
+         uint64_t obytes;   /**< Total number of transmitted bytes. */
+         uint64_t imissed;  /**< Total of RX missed packets. */
+         uint64_t ibadcrc;  /**< Total of RX packets with CRC error. */
+         uint64_t ibadlen;  /**< Total of RX packets with bad length. */
+     }
+
+  Note: postfix comments should be aligned with spaces not tabs in accordance
+  with the :ref:`coding_style`.
+
+* If a single comment type can't be used, due to line length limitations then
+  prefix comments should be preferred.
+  For example this section of the code contains prefix comments, postfix comments on the same line and postfix
+  comments on a separate line:
+
+  .. code-block:: c
+
+     /** Number of elements in the elt_pa array. */
+     uint32_t    pg_num __rte_cache_aligned;
+     uint32_t    pg_shift;     /**< LOG2 of the physical pages. */
+     uintptr_t   pg_mask;      /**< Physical page mask value. */
+     uintptr_t   elt_va_start;
+     /**< Virtual address of the first mempool object. */
+     uintptr_t   elt_va_end;
+     /**< Virtual address of the <size + 1> mempool object. */
+     phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
+     /**< Array of physical page addresses for the mempool buffer. */
+
+  This doesn't have an effect on the rendered documentation but it is confusing for the developer reading the code.
+  It this case it would be clearer to use prefix comments throughout:
+
+  .. code-block:: c
+
+     /** Number of elements in the elt_pa array. */
+     uint32_t    pg_num __rte_cache_aligned;
+     /** LOG2 of the physical pages. */
+     uint32_t    pg_shift;
+     /** Physical page mask value. */
+     uintptr_t   pg_mask;
+     /** Virtual address of the first mempool object. */
+     uintptr_t   elt_va_start;
+     /** Virtual address of the <size + 1> mempool object. */
+     uintptr_t   elt_va_end;
+     /** Array of physical page addresses for the mempool buffer. */
+     phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
+
+* Check for Doxygen warnings in new code by checking the API documentation build::
+
+     make doc-api-html | grep "warning:"
+
+* Read the rendered section of the documentation that you have added for correctness, clarity and consistency
+  with the surrounding text.
-- 
1.8.1.4

Re: [dpdk-dev] [PATCH v2 3/3] doc: moved doxygen section to the doc guidelines

[Bruce Richardson]

On Fri, Jul 10, 2015 at 04:45:21PM +0100, John McNamara wrote:
> Moved and refactored the Doxygen guidelines from the Coding Style doc
> to the Documentation Guidelines doc. Replaced the existing Doxygen
> references with links.
> 
> Signed-off-by: John McNamara <john.mcnamara@intel.com>

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

Re: [dpdk-dev] [PATCH v2 0/3] doc: added guidelines on dpdk documentation

[Thomas Monjalon]

2015-07-10 16:45, John McNamara:
> This patchset:
> 
> * Adds guidelines on the purpose and structure of the DPDK documentation,
>   how to build it and guidelines for creating it and adding to it.
> 
> * Moves and refactors the Doxygen guidelines from the Coding Style doc to
>   the Documentation Guidelines doc.
> 
> As with the other guidelines the main idea is to document the status quo and
> then modify/add to it over time.
> 
> 
> V2:
> * Incorporates mailing list comments.
> 
> * Removed doc patch contribution guide. Will submit separately
>   as contribution guidelines.
> 
> V1:
> * Initial version.
> 
> John McNamara (3):
>   doc: set the default literal block format
>   doc: added guidelines on dpdk documentation
>   doc: moved doxygen section to the doc guidelines

Applied with 2 minor fixes, thanks