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 <http://mails.dpdk.org/archives/dev/>`_.
32 Contributors will need to `register for the mailing list <http://mails.dpdk.org/listinfo/dev>`_ in order to submit patches.
33 It is also worth registering for the DPDK `Patchwork <http://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 http://dpdk.org/git/dpdk
135 sub-repositories (`list <http://git.dpdk.org/next>`_)::
137 git clone git://dpdk.org/next/dpdk-next-*
138 git clone http://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 * New external functions should be added to the local ``version.map`` file.
150 See the :doc:`Guidelines for ABI policy and versioning </contributing/versioning>`.
151 New external functions should also be added in alphabetical order.
153 * Important changes will require an addition to the release notes in ``doc/guides/rel_notes/``.
154 See the :ref:`Release Notes section of the Documentation Guidelines <doc_guidelines>` for details.
156 * Test the compilation works with different targets, compilers and options, see :ref:`contrib_check_compilation`.
158 * Don't break compilation between commits with forward dependencies in a patchset.
159 Each commit should compile on its own to allow for ``git bisect`` and continuous integration testing.
161 * Add tests to the ``app/test`` unit test framework where possible.
163 * Add documentation, if relevant, in the form of Doxygen comments or a User Guide in RST format.
164 See the :ref:`Documentation Guidelines <doc_guidelines>`.
166 Once the changes have been made you should commit them to your local repo.
168 For small changes, that do not require specific explanations, it is better to keep things together in the
170 Larger changes that require different explanations should be separated into logical patches in a patchset.
171 A good way of thinking about whether a patch should be split is to consider whether the change could be
172 applied without dependencies as a backport.
174 It is better to keep the related documentation changes in the same patch
175 file as the code, rather than one big documentation patch at then end of a
176 patchset. This makes it easier for future maintenance and development of the
179 As a guide to how patches should be structured run ``git log`` on similar files.
182 Commit Messages: Subject Line
183 -----------------------------
185 The first, summary, line of the git commit message becomes the subject line of the patch email.
186 Here are some guidelines for the summary line:
188 * The summary line must capture the area and the impact of the change.
190 * The summary line should be around 50 characters.
192 * The summary line should be lowercase apart from acronyms.
194 * It should be prefixed with the component name (use git log to check existing components).
197 ixgbe: fix offload config option name
199 config: increase max queues per port
201 * Use the imperative of the verb (like instructions to the code base).
203 * Don't add a period/full stop to the subject line or you will end up two in the patch name: ``dpdk_description..patch``.
205 The actual email subject line should be prefixed by ``[PATCH]`` and the version, if greater than v1,
206 for example: ``PATCH v2``.
207 The is generally added by ``git send-email`` or ``git format-patch``, see below.
209 If you are submitting an RFC draft of a feature you can use ``[RFC]`` instead of ``[PATCH]``.
210 An RFC patch doesn't have to be complete.
211 It is intended as a way of getting early feedback.
214 Commit Messages: Body
215 ---------------------
217 Here are some guidelines for the body of a commit message:
219 * The body of the message should describe the issue being fixed or the feature being added.
220 It is important to provide enough information to allow a reviewer to understand the purpose of the patch.
222 * When the change is obvious the body can be blank, apart from the signoff.
224 * The commit message must end with a ``Signed-off-by:`` line which is added using::
226 git commit --signoff # or -s
228 The purpose of the signoff is explained in the
229 `Developer's Certificate of Origin <https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1>`_
230 section of the Linux kernel guidelines.
234 All developers must ensure that they have read and understood the
235 Developer's Certificate of Origin section of the documentation prior
236 to applying the signoff and submitting a patch.
238 * The signoff must be a real name and not an alias or nickname.
239 More than one signoff is allowed.
241 * The text of the commit message should be wrapped at 72 characters.
243 * When fixing a regression, it is required to reference the id of the commit
244 which introduced the bug, and put the original author of that commit on CC.
245 You can generate the required lines using the following git alias, which prints
246 the commit SHA and the author of the original code::
248 git config alias.fixline "log -1 --abbrev=12 --format='Fixes: %h (\"%s\")%nCc: %ae'"
250 The output of ``git fixline <SHA>`` must then be added to the commit message::
252 doc: fix some parameter description
254 Update the docs, fixing description of some parameter.
256 Fixes: abcdefgh1234 ("doc: add some parameter")
257 Cc: author@example.com
259 Signed-off-by: Alex Smith <alex.smith@example.com>
261 * When fixing an error or warning it is useful to add the error message and instructions on how to reproduce it.
263 * Use correct capitalization, punctuation and spelling.
265 In addition to the ``Signed-off-by:`` name the commit messages can also have
266 tags for who reported, suggested, tested and reviewed the patch being
267 posted. Please refer to the `Tested, Acked and Reviewed by`_ section.
269 Patch Fix Related Issues
270 ~~~~~~~~~~~~~~~~~~~~~~~~
272 `Coverity <https://scan.coverity.com/projects/dpdk-data-plane-development-kit>`_
273 is a tool for static code analysis.
274 It is used as a cloud-based service used to scan the DPDK source code,
275 and alert developers of any potential defects in the source code.
276 When fixing an issue found by Coverity, the patch must contain a Coverity issue ID
277 in the body of the commit message. For example::
280 doc: fix some parameter description
282 Update the docs, fixing description of some parameter.
284 Coverity issue: 12345
285 Fixes: abcdefgh1234 ("doc: add some parameter")
286 Cc: author@example.com
288 Signed-off-by: Alex Smith <alex.smith@example.com>
291 `Bugzilla <https://bugs.dpdk.org>`_
292 is a bug- or issue-tracking system.
293 Bug-tracking systems allow individual or groups of developers
294 effectively to keep track of outstanding problems with their product.
295 When fixing an issue raised in Bugzilla, the patch must contain
296 a Bugzilla issue ID in the body of the commit message.
299 doc: fix some parameter description
301 Update the docs, fixing description of some parameter.
304 Fixes: abcdefgh1234 ("doc: add some parameter")
305 Cc: author@example.com
307 Signed-off-by: Alex Smith <alex.smith@example.com>
309 Patch for Stable Releases
310 ~~~~~~~~~~~~~~~~~~~~~~~~~
312 All fix patches to the master branch that are candidates for backporting
313 should also be CCed to the `stable@dpdk.org <http://mails.dpdk.org/listinfo/stable>`_
315 In the commit message body the Cc: stable@dpdk.org should be inserted as follows::
317 doc: fix some parameter description
319 Update the docs, fixing description of some parameter.
321 Fixes: abcdefgh1234 ("doc: add some parameter")
324 Signed-off-by: Alex Smith <alex.smith@example.com>
326 For further information on stable contribution you can go to
327 :doc:`Stable Contribution Guide <stable>`.
333 It is possible to send patches directly from git but for new contributors it is recommended to generate the
334 patches with ``git format-patch`` and then when everything looks okay, and the patches have been checked, to
335 send them with ``git send-email``.
337 Here are some examples of using ``git format-patch`` to generate patches:
339 .. code-block:: console
341 # Generate a patch from the last commit.
344 # Generate a patch from the last 3 commits.
347 # Generate the patches in a directory.
348 git format-patch -3 -o ~/patch/
350 # Add a cover letter to explain a patchset.
351 git format-patch -3 -o ~/patch/ --cover-letter
353 # Add a prefix with a version number.
354 git format-patch -3 -o ~/patch/ -v 2
357 Cover letters are useful for explaining a patchset and help to generate a logical threading to the patches.
358 Smaller notes can be put inline in the patch after the ``---`` separator, for example::
360 Subject: [PATCH] fm10k/base: add FM10420 device ids
362 Add the device ID for Boulder Rapids and Atwood Channel to enable
363 drivers to support those devices.
365 Signed-off-by: Alex Smith <alex.smith@example.com>
370 drivers/net/fm10k/base/fm10k_api.c | 6 ++++++
371 drivers/net/fm10k/base/fm10k_type.h | 6 ++++++
372 2 files changed, 12 insertions(+)
375 Version 2 and later of a patchset should also include a short log of the changes so the reviewer knows what has changed.
376 This can be added to the cover letter or the annotations.
381 * Fixed issued with version.map.
384 * Added i40e support.
385 * Renamed ethdev functions from rte_eth_ieee15888_*() to rte_eth_timesync_*()
386 since 802.1AS can be supported through the same interfaces.
389 .. _contrib_checkpatch:
394 Patches should be checked for formatting and syntax issues using the ``checkpatches.sh`` script in the ``devtools``
395 directory of the DPDK repo.
396 This uses the Linux kernel development tool ``checkpatch.pl`` which can be obtained by cloning, and periodically,
397 updating the Linux kernel sources.
399 The path to the original Linux script must be set in the environment variable ``DPDK_CHECKPATCH_PATH``.
400 This, and any other configuration variables required by the development tools, are loaded from the following
401 files, in order of preference::
404 ~/.config/dpdk/devel.config
405 /etc/dpdk/devel.config.
407 Once the environment variable the script can be run as follows::
409 devtools/checkpatches.sh ~/patch/
411 The script usage is::
413 checkpatches.sh [-h] [-q] [-v] [patch1 [patch2] ...]]"
417 * ``-h``: help, usage.
418 * ``-q``: quiet. Don't output anything for files without issues.
420 * ``patchX``: path to one or more patches.
422 Then the git logs should be checked using the ``check-git-log.sh`` script.
424 The script usage is::
426 check-git-log.sh [range]
428 Where the range is a ``git log`` option.
431 .. _contrib_check_compilation:
439 Compilation of patches and changes should be tested using the ``test-build.sh`` script in the ``devtools``
440 directory of the DPDK repo::
442 devtools/test-build.sh x86_64-native-linux-gcc+next+shared
444 The script usage is::
446 test-build.sh [-h] [-jX] [-s] [config1 [config2] ...]]
450 * ``-h``: help, usage.
451 * ``-jX``: use X parallel jobs in "make".
452 * ``-s``: short test with only first config and without examples/doc.
453 * ``config``: default config name plus config switches delimited with a ``+`` sign.
455 Examples of configs are::
457 x86_64-native-linux-gcc
458 x86_64-native-linux-gcc+next+shared
459 x86_64-native-linux-clang+shared
461 The builds can be modified via the following environmental variables:
463 * ``DPDK_BUILD_TEST_CONFIGS`` (target1+option1+option2 target2)
464 * ``DPDK_DEP_CFLAGS``
465 * ``DPDK_DEP_LDFLAGS``
466 * ``DPDK_DEP_PCAP`` (y/[n])
467 * ``DPDK_NOTIFY`` (notify-send)
469 These can be set from the command line or in the config files shown above in the :ref:`contrib_checkpatch`.
471 The recommended configurations and options to test compilation prior to submitting patches are::
473 x86_64-native-linux-gcc+shared+next
474 x86_64-native-linux-clang+shared
475 i686-native-linux-gcc
477 export DPDK_DEP_ZLIB=y
478 export DPDK_DEP_PCAP=y
479 export DPDK_DEP_SSL=y
484 Compilation of patches is to be tested with ``devtools/test-meson-builds.sh`` script.
486 The script internally checks for dependencies, then builds for several
487 combinations of compilation configuration.
493 Patches should be sent to the mailing list using ``git send-email``.
494 You can configure an external SMTP with something like the following::
497 smtpuser = name@domain.com
498 smtpserver = smtp.domain.com
502 See the `Git send-email <https://git-scm.com/docs/git-send-email>`_ documentation for more details.
504 The patches should be sent to ``dev@dpdk.org``.
505 If the patches are a change to existing files then you should send them TO the maintainer(s) and CC ``dev@dpdk.org``.
506 The appropriate maintainer can be found in the ``MAINTAINERS`` file::
508 git send-email --to maintainer@some.org --cc dev@dpdk.org 000*.patch
510 Script ``get-maintainer.sh`` can be used to select maintainers automatically::
512 git send-email --to-cmd ./devtools/get-maintainer.sh --cc dev@dpdk.org 000*.patch
514 New additions can be sent without a maintainer::
516 git send-email --to dev@dpdk.org 000*.patch
518 You can test the emails by sending it to yourself or with the ``--dry-run`` option.
520 If the patch is in relation to a previous email thread you can add it to the same thread using the Message ID::
522 git send-email --to dev@dpdk.org --in-reply-to <1234-foo@bar.com> 000*.patch
524 The Message ID can be found in the raw text of emails or at the top of each Patchwork patch,
525 `for example <http://patches.dpdk.org/patch/7646/>`_.
526 Shallow threading (``--thread --no-chain-reply-to``) is preferred for a patch series.
528 Once submitted your patches will appear on the mailing list and in Patchwork.
530 Experienced committers may send patches directly with ``git send-email`` without the ``git format-patch`` step.
531 The options ``--annotate`` and ``confirm = always`` are recommended for checking patches before sending.
534 Backporting patches for Stable Releases
535 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
537 Sometimes a maintainer or contributor wishes, or can be asked, to send a patch
538 for a stable release rather than mainline.
539 In this case the patch(es) should be sent to ``stable@dpdk.org``,
540 not to ``dev@dpdk.org``.
542 Given that there are multiple stable releases being maintained at the same time,
543 please specify exactly which branch(es) the patch is for
544 using ``git send-email --subject-prefix='PATCH 16.11' ...``
545 and also optionally in the cover letter or in the annotation.
551 Patches are reviewed by the community, relying on the experience and
552 collaboration of the members to double-check each other's work. There are a
553 number of ways to indicate that you have checked a patch on the mailing list.
556 Tested, Acked and Reviewed by
557 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
559 To indicate that you have interacted with a patch on the mailing list you
560 should respond to the patch in an email with one of the following tags:
568 The tag should be on a separate line as follows::
570 tag-here: Name Surname <email@address.com>
572 Each of these tags has a specific meaning. In general, the DPDK community
573 follows the kernel usage of the tags. A short summary of the meanings of each
574 tag is given here for reference:
576 .. _statement: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#reviewer-s-statement-of-oversight
578 ``Reviewed-by:`` is a strong statement_ that the patch is an appropriate state
579 for merging without any remaining serious technical issues. Reviews from
580 community members who are known to understand the subject area and to perform
581 thorough reviews will increase the likelihood of the patch getting merged.
583 ``Acked-by:`` is a record that the person named was not directly involved in
584 the preparation of the patch but wishes to signify and record their acceptance
587 ``Tested-by:`` indicates that the patch has been successfully tested (in some
588 environment) by the person named.
590 ``Reported-by:`` is used to acknowledge person who found or reported the bug.
592 ``Suggested-by:`` indicates that the patch idea was suggested by the named
597 Steps to getting your patch merged
598 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
600 The more work you put into the previous steps the easier it will be to get a
601 patch accepted. The general cycle for patch review and acceptance is:
605 #. Check the automatic test reports in the coming hours.
607 #. Wait for review comments. While you are waiting review some other patches.
609 #. Fix the review comments and submit a ``v n+1`` patchset::
611 git format-patch -3 -v 2
613 #. Update Patchwork to mark your previous patches as "Superseded".
615 #. If the patch is deemed suitable for merging by the relevant maintainer(s) or other developers they will ``ack``
616 the patch with an email that includes something like::
618 Acked-by: Alex Smith <alex.smith@example.com>
620 **Note**: When acking patches please remove as much of the text of the patch email as possible.
621 It is generally best to delete everything after the ``Signed-off-by:`` line.
623 #. Having the patch ``Reviewed-by:`` and/or ``Tested-by:`` will also help the patch to be accepted.
625 #. If the patch isn't deemed suitable based on being out of scope or conflicting with existing functionality
626 it may receive a ``nack``.
627 In this case you will need to make a more convincing technical argument in favor of your patches.
629 #. In addition a patch will not be accepted if it doesn't address comments from a previous version with fixes or
632 #. It is the responsibility of a maintainer to ensure that patches are reviewed and to provide an ``ack`` or
633 ``nack`` of those patches as appropriate.
635 #. Once a patch has been acked by the relevant maintainer, reviewers may still comment on it for a further
636 two weeks. After that time, the patch should be merged into the relevant git tree for the next release.
637 Additional notes and restrictions:
639 * Patches should be acked by a maintainer at least two days before the release merge
640 deadline, in order to make that release.
641 * For patches acked with less than two weeks to go to the merge deadline, all additional
642 comments should be made no later than two days before the merge deadline.
643 * After the appropriate time for additional feedback has passed, if the patch has not yet
644 been merged to the relevant tree by the committer, it should be treated as though it had,
645 in that any additional changes needed to it must be addressed by a follow-on patch, rather
646 than rework of the original.
647 * Trivial patches may be merged sooner than described above at the tree committer's