+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright 2018 The DPDK contributors
+
.. _coding_style:
DPDK Coding Style
License Header
~~~~~~~~~~~~~~
-Each file should begin with a special comment containing the appropriate copyright and license for the file.
-Generally this is the BSD License, except for code for Linux Kernel modules.
+Each file must begin with a special comment containing the
+`Software Package Data Exchange (SPDX) License Identfier <https://spdx.org/using-spdx-license-identifier>`_.
+
+Generally this is the BSD License, except for code granted special exceptions.
+The SPDX licences identifier is sufficient, a file should not contain
+an additional text version of the license (boilerplate).
+
After any copyright header, a blank line should be left before any other contents, e.g. include statements in a C file.
C Preprocessor Directives
* Use of the structures should be by separate variable declarations and those declarations must be extern if they are declared in a header file.
* Externally visible structure definitions should have the structure name prefixed by ``rte_`` to avoid namespace collisions.
+.. note::
+
+ Uses of ``bool`` in structures are not preferred as is wastes space and
+ it's also not clear as to what type size the bool is. A preferred use of
+ ``bool`` is mainly as a return type from functions that return true/false,
+ and maybe local variable functions.
+
+ Ref: `LKML <https://lkml.org/lkml/2017/11/21/384>`_
+
Queues
~~~~~~
DPDK also provides an optimized way to store elements in lockless rings.
This should be used in all data-path code, when there are several consumer and/or producers to avoid locking for concurrent access.
+Naming
+------
+
+For symbol names and documentation, new usage of
+'master / slave' (or 'slave' independent of 'master') and 'blacklist /
+whitelist' is not allowed.
+
+Recommended replacements for 'master / slave' are:
+ '{primary,main} / {secondary,replica,subordinate}'
+ '{initiator,requester} / {target,responder}'
+ '{controller,host} / {device,worker,proxy}'
+ 'leader / follower'
+ 'director / performer'
+
+Recommended replacements for 'blacklist/whitelist' are:
+ 'denylist / allowlist'
+ 'blocklist / passlist'
+
+Exceptions for introducing new usage is to maintain compatibility
+with an existing (as of 2020) hardware or protocol
+specification that mandates those terms.
+
+
Typedefs
~~~~~~~~
typedef int (lcore_function_t)(void *);
/* launch a function of lcore_function_t type */
- int rte_eal_remote_launch(lcore_function_t *f, void *arg, unsigned slave_id);
+ int rte_eal_remote_launch(lcore_function_t *f, void *arg, unsigned worker_id);
C Indentation
* is DEBUG) */
rte_log_set_level(my_logtype2, RTE_LOG_NOTICE);
- /* enable all PMD logs (whose identifier string starts with "pmd") */
- rte_log_set_level_regexp("pmd.*", RTE_LOG_DEBUG);
+ /* enable all PMD logs (whose identifier string starts with "pmd.") */
+ rte_log_set_level_pattern("pmd.*", RTE_LOG_DEBUG);
/* log in debug level */
rte_log_set_global_level(RTE_LOG_DEBUG);
- RTE_LOG(DEBUG, my_logtype1, "this is is a debug level message\n");
- RTE_LOG(INFO, my_logtype1, "this is is a info level message\n");
- RTE_LOG(WARNING, my_logtype1, "this is is a warning level message\n");
- RTE_LOG(WARNING, my_logtype2, "this is is a debug level message (not displayed)\n");
+ RTE_LOG(DEBUG, my_logtype1, "this is a debug level message\n");
+ RTE_LOG(INFO, my_logtype1, "this is a info level message\n");
+ RTE_LOG(WARNING, my_logtype1, "this is a warning level message\n");
+ RTE_LOG(WARNING, my_logtype2, "this is a debug level message (not displayed)\n");
/* log in info level */
rte_log_set_global_level(RTE_LOG_INFO);
* The virtio network PMD in ``drivers/net/virtio`` uses ``pmd.net.virtio``
* The eventdev software poll mode driver in ``drivers/event/sw`` uses ``pmd.event.sw``
* The octeontx mempool driver in ``drivers/mempool/octeontx`` uses ``pmd.mempool.octeontx``
- * The DPDK hash library in ``lib/librte_hash`` uses ``lib.hash``
+ * The DPDK hash library in ``lib/hash`` uses ``lib.hash``
Specializations
~~~~~~~~~~~~~~~
* PF/VF mailbox output: ``type.section.name.mbox``
A real world example is the i40e poll mode driver which exposes two
-specializations, one for initialization ``pmd.i40e.init`` and the other for
-the remaining driver logs ``pmd.i40e.driver``.
+specializations, one for initialization ``pmd.net.i40e.init`` and the other for
+the remaining driver logs ``pmd.net.i40e.driver``.
Note that specializations have no formatting rules, but please follow
a precedent if one exists. In order to see all current log topics and
Python Code
-----------
-All Python code should work with Python 2.7+ and 3.2+ and be compliant with
+All Python code should be compliant with
`PEP8 (Style Guide for Python Code) <https://www.python.org/dev/peps/pep-0008/>`_.
The ``pep8`` tool can be used for testing compliance with the guidelines.
Integrating with the Build System
---------------------------------
-DPDK supports being built in two different ways:
+DPDK is built using the tools ``meson`` and ``ninja``.
-* using ``make`` - or more specifically "GNU make", i.e. ``gmake`` on FreeBSD
-* using the tools ``meson`` and ``ninja``
+.. note::
-Any new library or driver to be integrated into DPDK should support being
-built with both systems. While building using ``make`` is a legacy approach, and
-most build-system enhancements are being done using ``meson`` and ``ninja``
-there are no plans at this time to deprecate the legacy ``make`` build system.
+ In order to catch possible issues as soon as possible,
+ it is recommended that developers build DPDK in "developer mode" to enable additional checks.
+ By default, this mode is enabled if the build is being done from a git checkout,
+ but the mode can be manually enabled/disabled using the
+ ``developer_mode`` meson configuration option.
-Therefore all new component additions should include both a ``Makefile`` and a
-``meson.build`` file, and should be added to the component lists in both the
-``Makefile`` and ``meson.build`` files in the relevant top-level directory:
+Therefore all new component additions should include a ``meson.build`` file,
+and should be added to the component lists in the ``meson.build`` files in the
+relevant top-level directory:
either ``lib`` directory or a ``driver`` subdirectory.
-Makefile Contents
-~~~~~~~~~~~~~~~~~
-
-The ``Makefile`` for the component should be of the following format, where
-``<name>`` corresponds to the name of the library in question, e.g. hash,
-lpm, etc. For drivers, the same format of Makefile is used.
-
-.. code-block:: none
-
- # pull in basic DPDK definitions, including whether library is to be
- # built or not
- include $(RTE_SDK)/mk/rte.vars.mk
-
- # library name
- LIB = librte_<name>.a
-
- # any library cflags needed. Generally add "-O3 $(WERROR_FLAGS)"
- CFLAGS += -O3
- CFLAGS += $(WERROR_FLAGS)
-
- # the symbol version information for the library, and .so version
- EXPORT_MAP := rte_<name>_version.map
- LIBABIVER := 1
-
- # all source filenames are stored in SRCS-y
- SRCS-$(CONFIG_RTE_LIBRTE_<NAME>) += rte_<name>.c
-
- # install includes
- SYMLINK-$(CONFIG_RTE_LIBRTE_<NAME>)-include += rte_<name>.h
-
- # pull in rules to build the library
- include $(RTE_SDK)/mk/rte.lib.mk
-
Meson Build File Contents - Libraries
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
sources = files('file1.c', ...)
- headers = files('file1.c', ...)
+ headers = files('file1.h', ...)
-The will build based on a number of conventions and assumptions within the DPDK
+This will build based on a number of conventions and assumptions within the DPDK
itself, for example, that the library name is the same as the directory name in
which the files are stored.
The optional fields are:
-allow_experimental_apis
- **Default Value = false**
- Used to allow the library to make use of APIs marked as experimental.
- Set to ``true`` if the C files in the library call any functions
- marked as experimental in any included header files.
-
build
**Default Value = true**
Used to optionally compile a library, based on its dependencies or
- environment. A simple example of use would be:
+ environment. When set to "false" the ``reason`` value, explained below, should
+ also be set to explain to the user why the component is not being built.
+ A simple example of use would be:
.. code-block:: python
- if host_machine.system() != 'linux'
+ if not is_linux
build = false
+ reason = 'only supported on Linux'
endif
installed to $PREFIX/include when ``ninja install`` is run. As with
source files, these should be specified using the meson ``files()``
function.
+ When ``check_includes`` build option is set to ``true``, each header file
+ has additional checks performed on it, for example to ensure that it is
+ not missing any include statements for dependent headers.
+ For header files which are public, but only included indirectly in
+ applications, these checks can be skipped by using the ``indirect_headers``
+ variable rather than ``headers``.
+
+indirect_headers
+ **Default Value = []**.
+ As with ``headers`` option above, except that the files are not checked
+ for all needed include files as part of a DPDK build when
+ ``check_includes`` is set to ``true``.
includes:
**Default Value = []**.
If a library's .so or .a file differs from that given in the directory
name, the name should be specified using this variable. In practice,
since the convention is that for a library called ``librte_xyz.so``, the
- sources are stored in a directory ``lib/librte_xyz``, this value should
+ sources are stored in a directory ``lib/xyz``, this value should
never be needed for new libraries.
.. note::
objects that were compiled up as part of another target given in the
included library ``meson.build`` file.
-version
- **Default Value = 1**.
- Specifies the ABI version of the library, and is used as the major
- version number of the resulting ``.so`` library.
+reason
+ **Default Value = '<unknown reason>'**.
+ This variable should be used when a library is not to be built i.e. when
+ ``build`` is set to "false", to specify the reason why a library will not be
+ built. For missing dependencies this should be of the form
+ ``'missing dependency, "libname"'``.
+
+use_function_versioning
+ **Default Value = false**.
+ Specifies if the library in question has ABI versioned functions. If it
+ has, this value should be set to ensure that the C files are compiled
+ twice with suitable parameters for each of shared or static library
+ builds.
Meson Build File Contents - Drivers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For drivers, the values are largely the same as for libraries. The variables
supported are:
-allow_experimental_apis
- As above.
-
build
As above.
using static libraries. Anything added here will be appended to the end
of the ``pkgconfig --libs`` output.
+reason
+ As above.
+
sources [mandatory]
As above
+headers
+ As above
+
version
As above
+
+
+Meson Coding Style
+------------------
+
+The following guidelines apply to the build system code in meson.build files in DPDK.
+
+* Indentation should be using 4 spaces, no hard tabs.
+
+* Line continuations should be doubly-indented to ensure visible difference from normal indentation.
+ Any line continuations beyond the first may be singly indented to avoid large amounts of indentation.
+
+* Lists of files or components must be alphabetical unless doing so would cause errors.
+
+* Two formats are supported for lists of files or list of components:
+
+ * For a small number of list entries, generally 3 or fewer, all elements may be put on a single line.
+ In this case, the opening and closing braces of the list must be on the same line as the list items.
+ No trailing comma is put on the final list entry.
+ * For lists with more than 3 items,
+ it is recommended that the lists be put in the files with a *single* entry per line.
+ In this case, the opening brace, or ``files`` function call must be on a line on its own,
+ and the closing brace must similarly be on a line on its own at the end.
+ To help with readability of nested sublists, the closing brace should be dedented to appear
+ at the same level as the opening braced statement.
+ The final list entry must have a trailing comma,
+ so that adding a new entry to the list never modifies any other line in the list.
+
+Examples::
+
+ sources = files('file1.c', 'file2.c')
+
+ subdirs = ['dir1', 'dir2']
+
+ headers = files(
+ 'header1.c',
+ 'header2.c',
+ 'header3.c', # always include trailing comma
+ ) # closing brace at indent level of opening brace
+
+ components = [
+ 'comp1',
+ 'comp2',
+ ...
+ 'compN',
+ ]
git.droids-corp.org / dpdk.git / blobdiff