3 Contributing Code to DPDK
4 =========================
6 This document outlines the guidelines for submitting code to DPDK.
8 The DPDK development process is modelled (loosely) on the Linux Kernel development model so it is worth reading the
9 Linux kernel guide on submitting patches:
10 `How to Get Your Change Into the Linux Kernel <https://www.kernel.org/doc/html/latest/process/submitting-patches.html>`_.
11 The rationale for many of the DPDK guidelines is explained in greater detail in the kernel guidelines.
14 The DPDK Development Process
15 ----------------------------
17 The DPDK development process has the following features:
19 * The code is hosted in a public git repository.
20 * There is a mailing list where developers submit patches.
21 * There are maintainers for hierarchical components.
22 * Patches are reviewed publicly on the mailing list.
23 * Successfully reviewed patches are merged to the repository.
24 * Patches should be sent to the target repository or sub-tree, see below.
25 * All sub-repositories are merged into main repository for ``-rc1`` and ``-rc2`` versions of the release.
26 * After the ``-rc2`` release all patches should target the main repository.
28 The mailing list for DPDK development is `dev@dpdk.org <http://dpdk.org/ml/archives/dev/>`_.
29 Contributors will need to `register for the mailing list <http://dpdk.org/ml/listinfo/dev>`_ in order to submit patches.
30 It is also worth registering for the DPDK `Patchwork <http://dpdk.org/dev/patchwork/project/dpdk/list/>`_
32 The development process requires some familiarity with the ``git`` version control system.
33 Refer to the `Pro Git Book <http://www.git-scm.com/book/>`_ for further information.
38 The DPDK uses the Open Source BSD-3-Clause license for the core libraries and
39 drivers. The kernel components are GPL-2.0 licensed. DPDK uses single line
40 reference to Unique License Identifiers in source files as defined by the Linux
41 Foundation's `SPDX project <http://spdx.org/>`_.
43 DPDK uses first line of the file to be SPDX tag. In case of *#!* scripts, SPDX
44 tag can be placed in 2nd line of the file.
46 For example, to label a file as subject to the BSD-3-Clause license,
47 the following text would be used:
49 ``SPDX-License-Identifier: BSD-3-Clause``
51 To label a file as dual-licensed with BSD-3-Clause and GPL-2.0 (e.g., for code
52 that is shared between the kernel and userspace), the following text would be
55 ``SPDX-License-Identifier: (BSD-3-Clause OR GPL-2.0)``
57 Refer to ``licenses/README`` for more details.
59 Maintainers and Sub-trees
60 -------------------------
62 The DPDK maintenance hierarchy is divided into a main repository ``dpdk`` and sub-repositories ``dpdk-next-*``.
64 There are maintainers for the trees and for components within the tree.
66 Trees and maintainers are listed in the ``MAINTAINERS`` file. For example::
70 M: Some Name <some.name@email.com>
71 B: Another Name <another.name@email.com>
72 T: git://dpdk.org/next/dpdk-next-crypto
75 M: Some One <some.one@email.com>
76 F: drivers/crypto/aesni_gcm/
77 F: doc/guides/cryptodevs/aesni_gcm.rst
81 * ``M`` is a tree or component maintainer.
82 * ``B`` is a tree backup maintainer.
83 * ``T`` is a repository tree.
84 * ``F`` is a maintained file or directory.
86 Additional details are given in the ``MAINTAINERS`` file.
88 The role of the component maintainers is to:
90 * Review patches for the component or delegate the review.
91 The review should be done, ideally, within 1 week of submission to the mailing list.
92 * Add an ``acked-by`` to patches, or patchsets, that are ready for committing to a tree.
93 * Reply to questions asked about the component.
95 Component maintainers can be added or removed by submitting a patch to the ``MAINTAINERS`` file.
96 Maintainers should have demonstrated a reasonable level of contributions or reviews to the component area.
97 The maintainer should be confirmed by an ``ack`` from an established contributor.
98 There can be more than one component maintainer if desired.
100 The role of the tree maintainers is to:
102 * Maintain the overall quality of their tree.
103 This can entail additional review, compilation checks or other tests deemed necessary by the maintainer.
104 * Commit patches that have been reviewed by component maintainers and/or other contributors.
105 The tree maintainer should determine if patches have been reviewed sufficiently.
106 * Ensure that patches are reviewed in a timely manner.
107 * Prepare the tree for integration.
108 * Ensure that there is a designated back-up maintainer and coordinate a handover for periods where the
109 tree maintainer can't perform their role.
111 Tree maintainers can be added or removed by submitting a patch to the ``MAINTAINERS`` file.
112 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.
113 The maintainer should be confirmed by an ``ack`` from an existing tree maintainer.
114 Disagreements on trees or maintainers can be brought to the Technical Board.
116 The backup maintainer for the master tree should be selected from the existing sub-tree maintainers from the project.
117 The backup maintainer for a sub-tree should be selected from among the component maintainers within that sub-tree.
120 Getting the Source Code
121 -----------------------
123 The source code can be cloned using either of the following:
127 git clone git://dpdk.org/dpdk
128 git clone http://dpdk.org/git/dpdk
130 sub-repositories (`list <http://dpdk.org/browse/next>`_)::
132 git clone git://dpdk.org/next/dpdk-next-*
133 git clone http://dpdk.org/git/next/dpdk-next-*
138 Make your planned changes in the cloned ``dpdk`` repo. Here are some guidelines and requirements:
140 * Follow the :ref:`coding_style` guidelines.
142 * If you add new files or directories you should add your name to the ``MAINTAINERS`` file.
144 * New external functions should be added to the local ``version.map`` file.
145 See the :doc:`Guidelines for ABI policy and versioning </contributing/versioning>`.
146 New external functions should also be added in alphabetical order.
148 * Important changes will require an addition to the release notes in ``doc/guides/rel_notes/``.
149 See the :ref:`Release Notes section of the Documentation Guidelines <doc_guidelines>` for details.
151 * Test the compilation works with different targets, compilers and options, see :ref:`contrib_check_compilation`.
153 * Don't break compilation between commits with forward dependencies in a patchset.
154 Each commit should compile on its own to allow for ``git bisect`` and continuous integration testing.
156 * Add tests to the ``app/test`` unit test framework where possible.
158 * Add documentation, if relevant, in the form of Doxygen comments or a User Guide in RST format.
159 See the :ref:`Documentation Guidelines <doc_guidelines>`.
161 Once the changes have been made you should commit them to your local repo.
163 For small changes, that do not require specific explanations, it is better to keep things together in the
165 Larger changes that require different explanations should be separated into logical patches in a patchset.
166 A good way of thinking about whether a patch should be split is to consider whether the change could be
167 applied without dependencies as a backport.
169 As a guide to how patches should be structured run ``git log`` on similar files.
172 Commit Messages: Subject Line
173 -----------------------------
175 The first, summary, line of the git commit message becomes the subject line of the patch email.
176 Here are some guidelines for the summary line:
178 * The summary line must capture the area and the impact of the change.
180 * The summary line should be around 50 characters.
182 * The summary line should be lowercase apart from acronyms.
184 * It should be prefixed with the component name (use git log to check existing components).
187 ixgbe: fix offload config option name
189 config: increase max queues per port
191 * Use the imperative of the verb (like instructions to the code base).
193 * Don't add a period/full stop to the subject line or you will end up two in the patch name: ``dpdk_description..patch``.
195 The actual email subject line should be prefixed by ``[PATCH]`` and the version, if greater than v1,
196 for example: ``PATCH v2``.
197 The is generally added by ``git send-email`` or ``git format-patch``, see below.
199 If you are submitting an RFC draft of a feature you can use ``[RFC]`` instead of ``[PATCH]``.
200 An RFC patch doesn't have to be complete.
201 It is intended as a way of getting early feedback.
204 Commit Messages: Body
205 ---------------------
207 Here are some guidelines for the body of a commit message:
209 * The body of the message should describe the issue being fixed or the feature being added.
210 It is important to provide enough information to allow a reviewer to understand the purpose of the patch.
212 * When the change is obvious the body can be blank, apart from the signoff.
214 * The commit message must end with a ``Signed-off-by:`` line which is added using::
216 git commit --signoff # or -s
218 The purpose of the signoff is explained in the
219 `Developer's Certificate of Origin <https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1>`_
220 section of the Linux kernel guidelines.
224 All developers must ensure that they have read and understood the
225 Developer's Certificate of Origin section of the documentation prior
226 to applying the signoff and submitting a patch.
228 * The signoff must be a real name and not an alias or nickname.
229 More than one signoff is allowed.
231 * The text of the commit message should be wrapped at 72 characters.
233 * When fixing a regression, it is required to reference the id of the commit
234 which introduced the bug, and put the original author of that commit on CC.
235 You can generate the required lines using the following git alias, which prints
236 the commit SHA and the author of the original code::
238 git config alias.fixline "log -1 --abbrev=12 --format='Fixes: %h (\"%s\")%nCc: %ae'"
240 The output of ``git fixline <SHA>`` must then be added to the commit message::
242 doc: fix some parameter description
244 Update the docs, fixing description of some parameter.
246 Fixes: abcdefgh1234 ("doc: add some parameter")
247 Cc: author@example.com
249 Signed-off-by: Alex Smith <alex.smith@example.com>
251 * When fixing an error or warning it is useful to add the error message and instructions on how to reproduce it.
253 * Use correct capitalization, punctuation and spelling.
255 In addition to the ``Signed-off-by:`` name the commit messages can also have
256 tags for who reported, suggested, tested and reviewed the patch being
257 posted. Please refer to the `Tested, Acked and Reviewed by`_ section.
259 Coverity Related Patch Fixes
260 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
262 `Coverity <https://scan.coverity.com/projects/dpdk-data-plane-development-kit>`_
263 is a tool for static code analysis.
264 It is used as a cloud-based service used to scan the DPDK source code,
265 and alert developers of any potential defects in the source code.
266 When fixing an issue found by Coverity, the patch must contain a Coverity issue ID
267 in the body of the commit message. For example::
270 doc: fix some parameter description
272 Update the docs, fixing description of some parameter.
274 Coverity issue: 12345
275 Fixes: abcdefgh1234 ("doc: add some parameter")
276 Cc: author@example.com
278 Signed-off-by: Alex Smith <alex.smith@example.com>
280 Patch for Stable Releases
281 ~~~~~~~~~~~~~~~~~~~~~~~~~
283 All fix patches to the master branch that are candidates for backporting
284 should also be CCed to the `stable@dpdk.org <http://dpdk.org/ml/listinfo/stable>`_
286 In the commit message body the Cc: stable@dpdk.org should be inserted as follows::
288 doc: fix some parameter description
290 Update the docs, fixing description of some parameter.
292 Fixes: abcdefgh1234 ("doc: add some parameter")
295 Signed-off-by: Alex Smith <alex.smith@example.com>
297 For further information on stable contribution you can go to
298 :doc:`Stable Contribution Guide <stable>`.
304 It is possible to send patches directly from git but for new contributors it is recommended to generate the
305 patches with ``git format-patch`` and then when everything looks okay, and the patches have been checked, to
306 send them with ``git send-email``.
308 Here are some examples of using ``git format-patch`` to generate patches:
310 .. code-block:: console
312 # Generate a patch from the last commit.
315 # Generate a patch from the last 3 commits.
318 # Generate the patches in a directory.
319 git format-patch -3 -o ~/patch/
321 # Add a cover letter to explain a patchset.
322 git format-patch -3 -o ~/patch/ --cover-letter
324 # Add a prefix with a version number.
325 git format-patch -3 -o ~/patch/ -v 2
328 Cover letters are useful for explaining a patchset and help to generate a logical threading to the patches.
329 Smaller notes can be put inline in the patch after the ``---`` separator, for example::
331 Subject: [PATCH] fm10k/base: add FM10420 device ids
333 Add the device ID for Boulder Rapids and Atwood Channel to enable
334 drivers to support those devices.
336 Signed-off-by: Alex Smith <alex.smith@example.com>
341 drivers/net/fm10k/base/fm10k_api.c | 6 ++++++
342 drivers/net/fm10k/base/fm10k_type.h | 6 ++++++
343 2 files changed, 12 insertions(+)
346 Version 2 and later of a patchset should also include a short log of the changes so the reviewer knows what has changed.
347 This can be added to the cover letter or the annotations.
352 * Fixed issued with version.map.
355 * Added i40e support.
356 * Renamed ethdev functions from rte_eth_ieee15888_*() to rte_eth_timesync_*()
357 since 802.1AS can be supported through the same interfaces.
360 .. _contrib_checkpatch:
365 Patches should be checked for formatting and syntax issues using the ``checkpatches.sh`` script in the ``devtools``
366 directory of the DPDK repo.
367 This uses the Linux kernel development tool ``checkpatch.pl`` which can be obtained by cloning, and periodically,
368 updating the Linux kernel sources.
370 The path to the original Linux script must be set in the environment variable ``DPDK_CHECKPATCH_PATH``.
371 This, and any other configuration variables required by the development tools, are loaded from the following
372 files, in order of preference::
375 ~/.config/dpdk/devel.config
376 /etc/dpdk/devel.config.
378 Once the environment variable the script can be run as follows::
380 devtools/checkpatches.sh ~/patch/
382 The script usage is::
384 checkpatches.sh [-h] [-q] [-v] [patch1 [patch2] ...]]"
388 * ``-h``: help, usage.
389 * ``-q``: quiet. Don't output anything for files without issues.
391 * ``patchX``: path to one or more patches.
393 Then the git logs should be checked using the ``check-git-log.sh`` script.
395 The script usage is::
397 check-git-log.sh [range]
399 Where the range is a ``git log`` option.
402 .. _contrib_check_compilation:
407 Compilation of patches and changes should be tested using the ``test-build.sh`` script in the ``devtools``
408 directory of the DPDK repo::
410 devtools/test-build.sh x86_64-native-linuxapp-gcc+next+shared
412 The script usage is::
414 test-build.sh [-h] [-jX] [-s] [config1 [config2] ...]]
418 * ``-h``: help, usage.
419 * ``-jX``: use X parallel jobs in "make".
420 * ``-s``: short test with only first config and without examples/doc.
421 * ``config``: default config name plus config switches delimited with a ``+`` sign.
423 Examples of configs are::
425 x86_64-native-linuxapp-gcc
426 x86_64-native-linuxapp-gcc+next+shared
427 x86_64-native-linuxapp-clang+shared
429 The builds can be modified via the following environmental variables:
431 * ``DPDK_BUILD_TEST_CONFIGS`` (target1+option1+option2 target2)
432 * ``DPDK_DEP_CFLAGS``
433 * ``DPDK_DEP_LDFLAGS``
434 * ``DPDK_DEP_PCAP`` (y/[n])
435 * ``DPDK_NOTIFY`` (notify-send)
437 These can be set from the command line or in the config files shown above in the :ref:`contrib_checkpatch`.
439 The recommended configurations and options to test compilation prior to submitting patches are::
441 x86_64-native-linuxapp-gcc+shared+next
442 x86_64-native-linuxapp-clang+shared
443 i686-native-linuxapp-gcc
445 export DPDK_DEP_ZLIB=y
446 export DPDK_DEP_PCAP=y
447 export DPDK_DEP_SSL=y
453 Patches should be sent to the mailing list using ``git send-email``.
454 You can configure an external SMTP with something like the following::
457 smtpuser = name@domain.com
458 smtpserver = smtp.domain.com
462 See the `Git send-email <https://git-scm.com/docs/git-send-email>`_ documentation for more details.
464 The patches should be sent to ``dev@dpdk.org``.
465 If the patches are a change to existing files then you should send them TO the maintainer(s) and CC ``dev@dpdk.org``.
466 The appropriate maintainer can be found in the ``MAINTAINERS`` file::
468 git send-email --to maintainer@some.org --cc dev@dpdk.org 000*.patch
470 Script ``get-maintainer.sh`` can be used to select maintainers automatically::
472 git send-email --to-cmd ./devtools/get-maintainer.sh --cc dev@dpdk.org 000*.patch
474 New additions can be sent without a maintainer::
476 git send-email --to dev@dpdk.org 000*.patch
478 You can test the emails by sending it to yourself or with the ``--dry-run`` option.
480 If the patch is in relation to a previous email thread you can add it to the same thread using the Message ID::
482 git send-email --to dev@dpdk.org --in-reply-to <1234-foo@bar.com> 000*.patch
484 The Message ID can be found in the raw text of emails or at the top of each Patchwork patch,
485 `for example <http://dpdk.org/dev/patchwork/patch/7646/>`_.
486 Shallow threading (``--thread --no-chain-reply-to``) is preferred for a patch series.
488 Once submitted your patches will appear on the mailing list and in Patchwork.
490 Experienced committers may send patches directly with ``git send-email`` without the ``git format-patch`` step.
491 The options ``--annotate`` and ``confirm = always`` are recommended for checking patches before sending.
494 Backporting patches for Stable Releases
495 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
497 Sometimes a maintainer or contributor wishes, or can be asked, to send a patch
498 for a stable release rather than mainline.
499 In this case the patch(es) should be sent to ``stable@dpdk.org``,
500 not to ``dev@dpdk.org``.
502 Given that there are multiple stable releases being maintained at the same time,
503 please specify exactly which branch(es) the patch is for
504 using ``git send-email --subject-prefix='PATCH 16.11' ...``
505 and also optionally in the cover letter or in the annotation.
511 Patches are reviewed by the community, relying on the experience and
512 collaboration of the members to double-check each other's work. There are a
513 number of ways to indicate that you have checked a patch on the mailing list.
516 Tested, Acked and Reviewed by
517 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
519 To indicate that you have interacted with a patch on the mailing list you
520 should respond to the patch in an email with one of the following tags:
528 The tag should be on a separate line as follows::
530 tag-here: Name Surname <email@address.com>
532 Each of these tags has a specific meaning. In general, the DPDK community
533 follows the kernel usage of the tags. A short summary of the meanings of each
534 tag is given here for reference:
536 .. _statement: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#reviewer-s-statement-of-oversight
538 ``Reviewed-by:`` is a strong statement_ that the patch is an appropriate state
539 for merging without any remaining serious technical issues. Reviews from
540 community members who are known to understand the subject area and to perform
541 thorough reviews will increase the likelihood of the patch getting merged.
543 ``Acked-by:`` is a record that the person named was not directly involved in
544 the preparation of the patch but wishes to signify and record their acceptance
547 ``Tested-by:`` indicates that the patch has been successfully tested (in some
548 environment) by the person named.
550 ``Reported-by:`` is used to acknowledge person who found or reported the bug.
552 ``Suggested-by:`` indicates that the patch idea was suggested by the named
557 Steps to getting your patch merged
558 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
560 The more work you put into the previous steps the easier it will be to get a
561 patch accepted. The general cycle for patch review and acceptance is:
565 #. Check the automatic test reports in the coming hours.
567 #. Wait for review comments. While you are waiting review some other patches.
569 #. Fix the review comments and submit a ``v n+1`` patchset::
571 git format-patch -3 -v 2
573 #. Update Patchwork to mark your previous patches as "Superseded".
575 #. If the patch is deemed suitable for merging by the relevant maintainer(s) or other developers they will ``ack``
576 the patch with an email that includes something like::
578 Acked-by: Alex Smith <alex.smith@example.com>
580 **Note**: When acking patches please remove as much of the text of the patch email as possible.
581 It is generally best to delete everything after the ``Signed-off-by:`` line.
583 #. Having the patch ``Reviewed-by:`` and/or ``Tested-by:`` will also help the patch to be accepted.
585 #. If the patch isn't deemed suitable based on being out of scope or conflicting with existing functionality
586 it may receive a ``nack``.
587 In this case you will need to make a more convincing technical argument in favor of your patches.
589 #. In addition a patch will not be accepted if it doesn't address comments from a previous version with fixes or
592 #. It is the responsibility of a maintainer to ensure that patches are reviewed and to provide an ``ack`` or
593 ``nack`` of those patches as appropriate.
595 #. Once a patch has been acked by the relevant maintainer, reviewers may still comment on it for a further
596 two weeks. After that time, the patch should be merged into the relevant git tree for the next release.
597 Additional notes and restrictions:
599 * Patches should be acked by a maintainer at least two days before the release merge
600 deadline, in order to make that release.
601 * For patches acked with less than two weeks to go to the merge deadline, all additional
602 comments should be made no later than two days before the merge deadline.
603 * After the appropriate time for additional feedback has passed, if the patch has not yet
604 been merged to the relevant tree by the committer, it should be treated as though it had,
605 in that any additional changes needed to it must be addressed by a follow-on patch, rather
606 than rework of the original.
607 * Trivial patches may be merged sooner than described above at the tree committer's
613 The following are the DPDK maintainers as listed in the ``MAINTAINERS`` file
614 in the DPDK root directory.
616 .. literalinclude:: ../../../MAINTAINERS