1 .. SPDX-License-Identifier: BSD-3-Clause
2 Copyright 2018 The DPDK contributors
6 Contributing Code to DPDK
7 =========================
9 This document outlines the guidelines for submitting code to DPDK.
11 The DPDK development process is modeled (loosely) on the Linux Kernel development model so it is worth reading the
12 Linux kernel guide on submitting patches:
13 `How to Get Your Change Into the Linux Kernel <https://www.kernel.org/doc/html/latest/process/submitting-patches.html>`_.
14 The rationale for many of the DPDK guidelines is explained in greater detail in the kernel guidelines.
17 The DPDK Development Process
18 ----------------------------
20 The DPDK development process has the following features:
22 * The code is hosted in a public git repository.
23 * There is a mailing list where developers submit patches.
24 * There are maintainers for hierarchical components.
25 * Patches are reviewed publicly on the mailing list.
26 * Successfully reviewed patches are merged to the repository.
27 * Patches should be sent to the target repository or sub-tree, see below.
28 * All sub-repositories are merged into main repository for ``-rc1`` and ``-rc2`` versions of the release.
29 * After the ``-rc2`` release all patches should target the main repository.
31 The mailing list for DPDK development is `dev@dpdk.org <https://mails.dpdk.org/archives/dev/>`_.
32 Contributors will need to `register for the mailing list <https://mails.dpdk.org/listinfo/dev>`_ in order to submit patches.
33 It is also worth registering for the DPDK `Patchwork <https://patches.dpdk.org/project/dpdk/list/>`_
35 If you are using the GitHub service, you can link your repository to
36 the ``travis-ci.org`` build service. When you push patches to your GitHub
37 repository, the travis service will automatically build your changes.
39 The development process requires some familiarity with the ``git`` version control system.
40 Refer to the `Pro Git Book <http://www.git-scm.com/book/>`_ for further information.
45 The DPDK uses the Open Source BSD-3-Clause license for the core libraries and
46 drivers. The kernel components are GPL-2.0 licensed. DPDK uses single line
47 reference to Unique License Identifiers in source files as defined by the Linux
48 Foundation's `SPDX project <http://spdx.org/>`_.
50 DPDK uses first line of the file to be SPDX tag. In case of *#!* scripts, SPDX
51 tag can be placed in 2nd line of the file.
53 For example, to label a file as subject to the BSD-3-Clause license,
54 the following text would be used:
56 ``SPDX-License-Identifier: BSD-3-Clause``
58 To label a file as dual-licensed with BSD-3-Clause and GPL-2.0 (e.g., for code
59 that is shared between the kernel and userspace), the following text would be
62 ``SPDX-License-Identifier: (BSD-3-Clause OR GPL-2.0)``
64 Refer to ``licenses/README`` for more details.
66 Maintainers and Sub-trees
67 -------------------------
69 The DPDK maintenance hierarchy is divided into a main repository ``dpdk`` and sub-repositories ``dpdk-next-*``.
71 There are maintainers for the trees and for components within the tree.
73 Trees and maintainers are listed in the ``MAINTAINERS`` file. For example::
77 M: Some Name <some.name@email.com>
78 T: git://dpdk.org/next/dpdk-next-crypto
81 M: Some One <some.one@email.com>
82 F: drivers/crypto/aesni_gcm/
83 F: doc/guides/cryptodevs/aesni_gcm.rst
87 * ``M`` is a tree or component maintainer.
88 * ``T`` is a repository tree.
89 * ``F`` is a maintained file or directory.
91 Additional details are given in the ``MAINTAINERS`` file.
93 The role of the component maintainers is to:
95 * Review patches for the component or delegate the review.
96 The review should be done, ideally, within 1 week of submission to the mailing list.
97 * Add an ``acked-by`` to patches, or patchsets, that are ready for committing to a tree.
98 * Reply to questions asked about the component.
100 Component maintainers can be added or removed by submitting a patch to the ``MAINTAINERS`` file.
101 Maintainers should have demonstrated a reasonable level of contributions or reviews to the component area.
102 The maintainer should be confirmed by an ``ack`` from an established contributor.
103 There can be more than one component maintainer if desired.
105 The role of the tree maintainers is to:
107 * Maintain the overall quality of their tree.
108 This can entail additional review, compilation checks or other tests deemed necessary by the maintainer.
109 * Commit patches that have been reviewed by component maintainers and/or other contributors.
110 The tree maintainer should determine if patches have been reviewed sufficiently.
111 * Ensure that patches are reviewed in a timely manner.
112 * Prepare the tree for integration.
113 * Ensure that there is a designated back-up maintainer and coordinate a handover for periods where the
114 tree maintainer can't perform their role.
116 Tree maintainers can be added or removed by submitting a patch to the ``MAINTAINERS`` file.
117 The proposer should justify the need for a new sub-tree and should have demonstrated a sufficient level of contributions in the area or to a similar area.
118 The maintainer should be confirmed by an ``ack`` from an existing tree maintainer.
119 Disagreements on trees or maintainers can be brought to the Technical Board.
121 The backup maintainer for the master tree should be selected from the existing sub-tree maintainers from the project.
122 The backup maintainer for a sub-tree should be selected from among the component maintainers within that sub-tree.
125 Getting the Source Code
126 -----------------------
128 The source code can be cloned using either of the following:
132 git clone git://dpdk.org/dpdk
133 git clone https://dpdk.org/git/dpdk
135 sub-repositories (`list <https://git.dpdk.org/next>`_)::
137 git clone git://dpdk.org/next/dpdk-next-*
138 git clone https://dpdk.org/git/next/dpdk-next-*
143 Make your planned changes in the cloned ``dpdk`` repo. Here are some guidelines and requirements:
145 * Follow the :ref:`coding_style` guidelines.
147 * If you add new files or directories you should add your name to the ``MAINTAINERS`` file.
149 * Initial submission of new PMDs should be prepared against a corresponding repo.
151 * Thus, for example, initial submission of a new network PMD should be
152 prepared against dpdk-next-net repo.
154 * Likewise, initial submission of a new crypto or compression PMD should be
155 prepared against dpdk-next-crypto repo.
157 * For other PMDs and more info, refer to the ``MAINTAINERS`` file.
159 * New external functions should be added to the local ``version.map`` file. See
160 the :doc:`ABI policy <abi_policy>` and :ref:`ABI versioning <abi_versioning>`
161 guides. New external functions should also be added in alphabetical order.
163 * Important changes will require an addition to the release notes in ``doc/guides/rel_notes/``.
164 See the :ref:`Release Notes section of the Documentation Guidelines <doc_guidelines>` for details.
166 * Test the compilation works with different targets, compilers and options, see :ref:`contrib_check_compilation`.
168 * Don't break compilation between commits with forward dependencies in a patchset.
169 Each commit should compile on its own to allow for ``git bisect`` and continuous integration testing.
171 * Add tests to the ``app/test`` unit test framework where possible.
173 * Add documentation, if relevant, in the form of Doxygen comments or a User Guide in RST format.
174 See the :ref:`Documentation Guidelines <doc_guidelines>`.
176 Once the changes have been made you should commit them to your local repo.
178 For small changes, that do not require specific explanations, it is better to keep things together in the
180 Larger changes that require different explanations should be separated into logical patches in a patchset.
181 A good way of thinking about whether a patch should be split is to consider whether the change could be
182 applied without dependencies as a backport.
184 It is better to keep the related documentation changes in the same patch
185 file as the code, rather than one big documentation patch at the end of a
186 patchset. This makes it easier for future maintenance and development of the
189 As a guide to how patches should be structured run ``git log`` on similar files.
192 Commit Messages: Subject Line
193 -----------------------------
195 The first, summary, line of the git commit message becomes the subject line of the patch email.
196 Here are some guidelines for the summary line:
198 * The summary line must capture the area and the impact of the change.
200 * The summary line should be around 50 characters.
202 * The summary line should be lowercase apart from acronyms.
204 * It should be prefixed with the component name (use git log to check existing components).
207 ixgbe: fix offload config option name
209 config: increase max queues per port
211 * Use the imperative of the verb (like instructions to the code base).
213 * Don't add a period/full stop to the subject line or you will end up two in the patch name: ``dpdk_description..patch``.
215 The actual email subject line should be prefixed by ``[PATCH]`` and the version, if greater than v1,
216 for example: ``PATCH v2``.
217 The is generally added by ``git send-email`` or ``git format-patch``, see below.
219 If you are submitting an RFC draft of a feature you can use ``[RFC]`` instead of ``[PATCH]``.
220 An RFC patch doesn't have to be complete.
221 It is intended as a way of getting early feedback.
224 Commit Messages: Body
225 ---------------------
227 Here are some guidelines for the body of a commit message:
229 * The body of the message should describe the issue being fixed or the feature being added.
230 It is important to provide enough information to allow a reviewer to understand the purpose of the patch.
232 * When the change is obvious the body can be blank, apart from the signoff.
234 * The commit message must end with a ``Signed-off-by:`` line which is added using::
236 git commit --signoff # or -s
238 The purpose of the signoff is explained in the
239 `Developer's Certificate of Origin <https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1>`_
240 section of the Linux kernel guidelines.
244 All developers must ensure that they have read and understood the
245 Developer's Certificate of Origin section of the documentation prior
246 to applying the signoff and submitting a patch.
248 * The signoff must be a real name and not an alias or nickname.
249 More than one signoff is allowed.
251 * The text of the commit message should be wrapped at 72 characters.
253 * When fixing a regression, it is required to reference the id of the commit
254 which introduced the bug, and put the original author of that commit on CC.
255 You can generate the required lines using the following git alias, which prints
256 the commit SHA and the author of the original code::
258 git config alias.fixline "log -1 --abbrev=12 --format='Fixes: %h (\"%s\")%nCc: %ae'"
260 The output of ``git fixline <SHA>`` must then be added to the commit message::
262 doc: fix some parameter description
264 Update the docs, fixing description of some parameter.
266 Fixes: abcdefgh1234 ("doc: add some parameter")
267 Cc: author@example.com
269 Signed-off-by: Alex Smith <alex.smith@example.com>
271 * When fixing an error or warning it is useful to add the error message and instructions on how to reproduce it.
273 * Use correct capitalization, punctuation and spelling.
275 In addition to the ``Signed-off-by:`` name the commit messages can also have
276 tags for who reported, suggested, tested and reviewed the patch being
277 posted. Please refer to the `Tested, Acked and Reviewed by`_ section.
279 Patch Fix Related Issues
280 ~~~~~~~~~~~~~~~~~~~~~~~~
282 `Coverity <https://scan.coverity.com/projects/dpdk-data-plane-development-kit>`_
283 is a tool for static code analysis.
284 It is used as a cloud-based service used to scan the DPDK source code,
285 and alert developers of any potential defects in the source code.
286 When fixing an issue found by Coverity, the patch must contain a Coverity issue ID
287 in the body of the commit message. For example::
290 doc: fix some parameter description
292 Update the docs, fixing description of some parameter.
294 Coverity issue: 12345
295 Fixes: abcdefgh1234 ("doc: add some parameter")
296 Cc: author@example.com
298 Signed-off-by: Alex Smith <alex.smith@example.com>
301 `Bugzilla <https://bugs.dpdk.org>`_
302 is a bug- or issue-tracking system.
303 Bug-tracking systems allow individual or groups of developers
304 effectively to keep track of outstanding problems with their product.
305 When fixing an issue raised in Bugzilla, the patch must contain
306 a Bugzilla issue ID in the body of the commit message.
309 doc: fix some parameter description
311 Update the docs, fixing description of some parameter.
314 Fixes: abcdefgh1234 ("doc: add some parameter")
315 Cc: author@example.com
317 Signed-off-by: Alex Smith <alex.smith@example.com>
319 Patch for Stable Releases
320 ~~~~~~~~~~~~~~~~~~~~~~~~~
322 All fix patches to the master branch that are candidates for backporting
323 should also be CCed to the `stable@dpdk.org <https://mails.dpdk.org/listinfo/stable>`_
325 In the commit message body the Cc: stable@dpdk.org should be inserted as follows::
327 doc: fix some parameter description
329 Update the docs, fixing description of some parameter.
331 Fixes: abcdefgh1234 ("doc: add some parameter")
334 Signed-off-by: Alex Smith <alex.smith@example.com>
336 For further information on stable contribution you can go to
337 :doc:`Stable Contribution Guide <stable>`.
342 Sometimes a patch or patchset can depend on another one.
343 To help the maintainers and automation tasks, please document this dependency in commit log or cover letter
344 with the following syntax:
346 ``Depends-on: series-NNNNN ("Title of the series")`` or ``Depends-on: patch-NNNNN ("Title of the patch")``
348 Where ``NNNNN`` is patchwork ID for patch or series::
350 doc: fix some parameter description
352 Update the docs, fixing description of some parameter.
354 Signed-off-by: Alex Smith <alex.smith@example.com>
356 Depends-on: series-10000 ("Title of the series")
361 It is possible to send patches directly from git but for new contributors it is recommended to generate the
362 patches with ``git format-patch`` and then when everything looks okay, and the patches have been checked, to
363 send them with ``git send-email``.
365 Here are some examples of using ``git format-patch`` to generate patches:
367 .. code-block:: console
369 # Generate a patch from the last commit.
372 # Generate a patch from the last 3 commits.
375 # Generate the patches in a directory.
376 git format-patch -3 -o ~/patch/
378 # Add a cover letter to explain a patchset.
379 git format-patch -3 -o ~/patch/ --cover-letter
381 # Add a prefix with a version number.
382 git format-patch -3 -o ~/patch/ -v 2
385 Cover letters are useful for explaining a patchset and help to generate a logical threading to the patches.
386 Smaller notes can be put inline in the patch after the ``---`` separator, for example::
388 Subject: [PATCH] fm10k/base: add FM10420 device ids
390 Add the device ID for Boulder Rapids and Atwood Channel to enable
391 drivers to support those devices.
393 Signed-off-by: Alex Smith <alex.smith@example.com>
398 drivers/net/fm10k/base/fm10k_api.c | 6 ++++++
399 drivers/net/fm10k/base/fm10k_type.h | 6 ++++++
400 2 files changed, 12 insertions(+)
403 Version 2 and later of a patchset should also include a short log of the changes so the reviewer knows what has changed.
404 This can be added to the cover letter or the annotations.
409 * Fixed issued with version.map.
412 * Added i40e support.
413 * Renamed ethdev functions from rte_eth_ieee15888_*() to rte_eth_timesync_*()
414 since 802.1AS can be supported through the same interfaces.
417 .. _contrib_checkpatch:
422 Patches should be checked for formatting and syntax issues using the ``checkpatches.sh`` script in the ``devtools``
423 directory of the DPDK repo.
424 This uses the Linux kernel development tool ``checkpatch.pl`` which can be obtained by cloning, and periodically,
425 updating the Linux kernel sources.
427 The path to the original Linux script must be set in the environment variable ``DPDK_CHECKPATCH_PATH``.
429 Spell checking of commonly misspelled words
430 can be enabled by downloading the codespell dictionary::
432 https://raw.githubusercontent.com/codespell-project/codespell/master/codespell_lib/data/dictionary.txt
434 The path to the downloaded ``dictionary.txt`` must be set
435 in the environment variable ``DPDK_CHECKPATCH_CODESPELL``.
437 Environment variables required by the development tools,
438 are loaded from the following files, in order of preference::
441 ~/.config/dpdk/devel.config
442 /etc/dpdk/devel.config.
444 Once the environment variable is set, the script can be run as follows::
446 devtools/checkpatches.sh ~/patch/
448 The script usage is::
450 checkpatches.sh [-h] [-q] [-v] [-nX|-r range|patch1 [patch2] ...]
452 Then the git logs should be checked using the ``check-git-log.sh`` script.
454 The script usage is::
456 check-git-log.sh [-h] [-nX|-r range]
458 For both of the above scripts, the -n option is used to specify a number of commits from HEAD,
459 and the -r option allows the user specify a ``git log`` range.
461 .. _contrib_check_compilation:
469 Compilation of patches and changes should be tested using the ``test-build.sh`` script in the ``devtools``
470 directory of the DPDK repo::
472 devtools/test-build.sh x86_64-native-linux-gcc+next+shared
474 The script usage is::
476 test-build.sh [-h] [-jX] [-s] [config1 [config2] ...]]
480 * ``-h``: help, usage.
481 * ``-jX``: use X parallel jobs in "make".
482 * ``-s``: short test with only first config and without examples/doc.
483 * ``config``: default config name plus config switches delimited with a ``+`` sign.
485 Examples of configs are::
487 x86_64-native-linux-gcc
488 x86_64-native-linux-gcc+next+shared
489 x86_64-native-linux-clang+shared
491 The builds can be modified via the following environmental variables:
493 * ``DPDK_BUILD_TEST_CONFIGS`` (target1+option1+option2 target2)
494 * ``DPDK_BUILD_TEST_DIR``
495 * ``DPDK_DEP_CFLAGS``
496 * ``DPDK_DEP_LDFLAGS``
497 * ``DPDK_DEP_PCAP`` (y/[n])
498 * ``DPDK_NOTIFY`` (notify-send)
500 These can be set from the command line or in the config files shown above in the :ref:`contrib_checkpatch`.
502 The recommended configurations and options to test compilation prior to submitting patches are::
504 x86_64-native-linux-gcc+shared+next
505 x86_64-native-linux-clang+shared
506 i686-native-linux-gcc
508 export DPDK_DEP_ZLIB=y
509 export DPDK_DEP_PCAP=y
510 export DPDK_DEP_SSL=y
515 Compilation of patches is to be tested with ``devtools/test-meson-builds.sh`` script.
517 The script internally checks for dependencies, then builds for several
518 combinations of compilation configuration.
519 By default, each build will be put in a subfolder of the current working directory.
520 However, if it is preferred to place the builds in a different location,
521 the environment variable ``DPDK_BUILD_TEST_DIR`` can be set to that desired location.
522 For example, setting ``DPDK_BUILD_TEST_DIR=__builds`` will put all builds
523 in a single subfolder called "__builds" created in the current directory.
524 Setting ``DPDK_BUILD_TEST_DIR`` to an absolute directory path e.g. ``/tmp`` is also supported.
527 .. _integrated_abi_check:
529 Checking ABI compatibility
530 --------------------------
532 By default, ABI compatibility checks are disabled.
534 To enable them, a reference version must be selected via the environment
535 variable ``DPDK_ABI_REF_VERSION``.
537 The ``devtools/test-build.sh`` and ``devtools/test-meson-builds.sh`` scripts
538 then build this reference version in a temporary directory and store the
539 results in a subfolder of the current working directory.
540 The environment variable ``DPDK_ABI_REF_DIR`` can be set so that the results go
541 to a different location.
547 Patches should be sent to the mailing list using ``git send-email``.
548 You can configure an external SMTP with something like the following::
551 smtpuser = name@domain.com
552 smtpserver = smtp.domain.com
556 See the `Git send-email <https://git-scm.com/docs/git-send-email>`_ documentation for more details.
558 The patches should be sent to ``dev@dpdk.org``.
559 If the patches are a change to existing files then you should send them TO the maintainer(s) and CC ``dev@dpdk.org``.
560 The appropriate maintainer can be found in the ``MAINTAINERS`` file::
562 git send-email --to maintainer@some.org --cc dev@dpdk.org 000*.patch
564 Script ``get-maintainer.sh`` can be used to select maintainers automatically::
566 git send-email --to-cmd ./devtools/get-maintainer.sh --cc dev@dpdk.org 000*.patch
568 New additions can be sent without a maintainer::
570 git send-email --to dev@dpdk.org 000*.patch
572 You can test the emails by sending it to yourself or with the ``--dry-run`` option.
574 If the patch is in relation to a previous email thread you can add it to the same thread using the Message ID::
576 git send-email --to dev@dpdk.org --in-reply-to <1234-foo@bar.com> 000*.patch
578 The Message ID can be found in the raw text of emails or at the top of each Patchwork patch,
579 `for example <https://patches.dpdk.org/patch/7646/>`_.
580 Shallow threading (``--thread --no-chain-reply-to``) is preferred for a patch series.
582 Once submitted your patches will appear on the mailing list and in Patchwork.
584 Experienced committers may send patches directly with ``git send-email`` without the ``git format-patch`` step.
585 The options ``--annotate`` and ``confirm = always`` are recommended for checking patches before sending.
588 Backporting patches for Stable Releases
589 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
591 Sometimes a maintainer or contributor wishes, or can be asked, to send a patch
592 for a stable release rather than mainline.
593 In this case the patch(es) should be sent to ``stable@dpdk.org``,
594 not to ``dev@dpdk.org``.
596 Given that there are multiple stable releases being maintained at the same time,
597 please specify exactly which branch(es) the patch is for
598 using ``git send-email --subject-prefix='PATCH 16.11' ...``
599 and also optionally in the cover letter or in the annotation.
605 Patches are reviewed by the community, relying on the experience and
606 collaboration of the members to double-check each other's work. There are a
607 number of ways to indicate that you have checked a patch on the mailing list.
610 Tested, Acked and Reviewed by
611 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
613 To indicate that you have interacted with a patch on the mailing list you
614 should respond to the patch in an email with one of the following tags:
622 The tag should be on a separate line as follows::
624 tag-here: Name Surname <email@address.com>
626 Each of these tags has a specific meaning. In general, the DPDK community
627 follows the kernel usage of the tags. A short summary of the meanings of each
628 tag is given here for reference:
630 .. _statement: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#reviewer-s-statement-of-oversight
632 ``Reviewed-by:`` is a strong statement_ that the patch is an appropriate state
633 for merging without any remaining serious technical issues. Reviews from
634 community members who are known to understand the subject area and to perform
635 thorough reviews will increase the likelihood of the patch getting merged.
637 ``Acked-by:`` is a record that the person named was not directly involved in
638 the preparation of the patch but wishes to signify and record their acceptance
641 ``Tested-by:`` indicates that the patch has been successfully tested (in some
642 environment) by the person named.
644 ``Reported-by:`` is used to acknowledge person who found or reported the bug.
646 ``Suggested-by:`` indicates that the patch idea was suggested by the named
651 Steps to getting your patch merged
652 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
654 The more work you put into the previous steps the easier it will be to get a
655 patch accepted. The general cycle for patch review and acceptance is:
659 #. Check the automatic test reports in the coming hours.
661 #. Wait for review comments. While you are waiting review some other patches.
663 #. Fix the review comments and submit a ``v n+1`` patchset::
665 git format-patch -3 -v 2
667 #. Update Patchwork to mark your previous patches as "Superseded".
669 #. If the patch is deemed suitable for merging by the relevant maintainer(s) or other developers they will ``ack``
670 the patch with an email that includes something like::
672 Acked-by: Alex Smith <alex.smith@example.com>
674 **Note**: When acking patches please remove as much of the text of the patch email as possible.
675 It is generally best to delete everything after the ``Signed-off-by:`` line.
677 #. Having the patch ``Reviewed-by:`` and/or ``Tested-by:`` will also help the patch to be accepted.
679 #. If the patch isn't deemed suitable based on being out of scope or conflicting with existing functionality
680 it may receive a ``nack``.
681 In this case you will need to make a more convincing technical argument in favor of your patches.
683 #. In addition a patch will not be accepted if it doesn't address comments from a previous version with fixes or
686 #. It is the responsibility of a maintainer to ensure that patches are reviewed and to provide an ``ack`` or
687 ``nack`` of those patches as appropriate.
689 #. Once a patch has been acked by the relevant maintainer, reviewers may still comment on it for a further
690 two weeks. After that time, the patch should be merged into the relevant git tree for the next release.
691 Additional notes and restrictions:
693 * Patches should be acked by a maintainer at least two days before the release merge
694 deadline, in order to make that release.
695 * For patches acked with less than two weeks to go to the merge deadline, all additional
696 comments should be made no later than two days before the merge deadline.
697 * After the appropriate time for additional feedback has passed, if the patch has not yet
698 been merged to the relevant tree by the committer, it should be treated as though it had,
699 in that any additional changes needed to it must be addressed by a follow-on patch, rather
700 than rework of the original.
701 * Trivial patches may be merged sooner than described above at the tree committer's