diff options
Diffstat (limited to 'docs/devel')
| -rw-r--r-- | docs/devel/build-environment.rst | 4 | ||||
| -rw-r--r-- | docs/devel/build-system.rst | 2 | ||||
| -rw-r--r-- | docs/devel/code-provenance.rst | 338 | ||||
| -rw-r--r-- | docs/devel/codebase.rst | 2 | ||||
| -rw-r--r-- | docs/devel/index-process.rst | 1 | ||||
| -rw-r--r-- | docs/devel/rust.rst | 63 | ||||
| -rw-r--r-- | docs/devel/submitting-a-patch.rst | 25 | ||||
| -rw-r--r-- | docs/devel/testing/functional.rst | 2 |
8 files changed, 366 insertions, 71 deletions
diff --git a/docs/devel/build-environment.rst b/docs/devel/build-environment.rst index f133ef2..661f6ea 100644 --- a/docs/devel/build-environment.rst +++ b/docs/devel/build-environment.rst @@ -97,11 +97,11 @@ build QEMU in MSYS2 itself. :: - pacman -S wget + pacman -S wget base-devel git wget https://raw.githubusercontent.com/msys2/MINGW-packages/refs/heads/master/mingw-w64-qemu/PKGBUILD # Some packages may be missing for your environment, installation will still # be done though. - makepkg -s PKGBUILD || true + makepkg --syncdeps --nobuild PKGBUILD || true Build on windows-aarch64 ++++++++++++++++++++++++ diff --git a/docs/devel/build-system.rst b/docs/devel/build-system.rst index 258cfad..2c88419 100644 --- a/docs/devel/build-system.rst +++ b/docs/devel/build-system.rst @@ -168,7 +168,7 @@ The required versions of the packages are stored in a configuration file ``pythondeps.toml``. The format is custom to QEMU, but it is documented at the top of the file itself and it should be easy to understand. The requirements should make it possible to use the version that is packaged -that is provided by supported distros. +by QEMU's supported distros. When dependencies are downloaded, instead, ``configure`` uses a "known good" version that is also listed in ``pythondeps.toml``. In this diff --git a/docs/devel/code-provenance.rst b/docs/devel/code-provenance.rst new file mode 100644 index 0000000..b5aae2e --- /dev/null +++ b/docs/devel/code-provenance.rst @@ -0,0 +1,338 @@ +.. _code-provenance: + +Code provenance +=============== + +Certifying patch submissions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The QEMU community **mandates** all contributors to certify provenance of +patch submissions they make to the project. To put it another way, +contributors must indicate that they are legally permitted to contribute to +the project. + +Certification is achieved with a low overhead by adding a single line to the +bottom of every git commit:: + + Signed-off-by: YOUR NAME <YOUR@EMAIL> + +The addition of this line asserts that the author of the patch is contributing +in accordance with the clauses specified in the +`Developer's Certificate of Origin <https://developercertificate.org>`__: + +.. _dco: + + Developer's Certificate of Origin 1.1 + + By making a contribution to this project, I certify that: + + (a) The contribution was created in whole or in part by me and I + have the right to submit it under the open source license + indicated in the file; or + + (b) The contribution is based upon previous work that, to the best + of my knowledge, is covered under an appropriate open source + license and I have the right under that license to submit that + work with modifications, whether created in whole or in part + by me, under the same open source license (unless I am + permitted to submit under a different license), as indicated + in the file; or + + (c) The contribution was provided directly to me by some other + person who certified (a), (b) or (c) and I have not modified + it. + + (d) I understand and agree that this project and the contribution + are public and that a record of the contribution (including all + personal information I submit with it, including my sign-off) is + maintained indefinitely and may be redistributed consistent with + this project or the open source license(s) involved. + +The name used with "Signed-off-by" does not need to be your legal name, nor +birth name, nor appear on any government ID. It is the identity you choose to +be known by in the community, but should not be anonymous, nor misrepresent +whom you are. + +It is generally expected that the name and email addresses used in one of the +``Signed-off-by`` lines, matches that of the git commit ``Author`` field. +It's okay if you subscribe or contribute to the list via more than one +address, but using multiple addresses in one commit just confuses +things. + +If the person sending the mail is not one of the patch authors, they are +nonetheless expected to add their own ``Signed-off-by`` to comply with the +DCO clause (c). + +Multiple authorship +~~~~~~~~~~~~~~~~~~~ + +It is not uncommon for a patch to have contributions from multiple authors. In +this scenario, git commits will usually be expected to have a ``Signed-off-by`` +line for each contributor involved in creation of the patch. Some edge cases: + + * The non-primary author's contributions were so trivial that they can be + considered not subject to copyright. In this case the secondary authors + need not include a ``Signed-off-by``. + + This case most commonly applies where QEMU reviewers give short snippets + of code as suggested fixes to a patch. The reviewers don't need to have + their own ``Signed-off-by`` added unless their code suggestion was + unusually large, but it is common to add ``Suggested-by`` as a credit + for non-trivial code. + + * Both contributors work for the same employer and the employer requires + copyright assignment. + + It can be said that in this case a ``Signed-off-by`` is indicating that + the person has permission to contribute from their employer who is the + copyright holder. It is nonetheless still preferable to include a + ``Signed-off-by`` for each contributor, as in some countries employees are + not able to assign copyright to their employer, and it also covers any + time invested outside working hours. + +When multiple ``Signed-off-by`` tags are present, they should be strictly kept +in order of authorship, from oldest to newest. + +Other commit tags +~~~~~~~~~~~~~~~~~ + +While the ``Signed-off-by`` tag is mandatory, there are a number of other tags +that are commonly used during QEMU development: + + * **``Reviewed-by``**: when a QEMU community member reviews a patch on the + mailing list, if they consider the patch acceptable, they should send an + email reply containing a ``Reviewed-by`` tag. Subsystem maintainers who + review a patch should add this even if they are also adding their + ``Signed-off-by`` to the same commit. + + * **``Acked-by``**: when a QEMU subsystem maintainer approves a patch that + touches their subsystem, but intends to allow a different maintainer to + queue it and send a pull request, they would send a mail containing a + ``Acked-by`` tag. Where a patch touches multiple subsystems, ``Acked-by`` + only implies review of the maintainers' own areas of responsibility. If a + maintainer wants to indicate they have done a full review they should use + a ``Reviewed-by`` tag. + + * **``Tested-by``**: when a QEMU community member has functionally tested the + behaviour of the patch in some manner, they should send an email reply + containing a ``Tested-by`` tag. + + * **``Reported-by``**: when a QEMU community member reports a problem via the + mailing list, or some other informal channel that is not the issue tracker, + it is good practice to credit them by including a ``Reported-by`` tag on + any patch fixing the issue. When the problem is reported via the GitLab + issue tracker, however, it is sufficient to just include a link to the + issue. + + * **``Suggested-by``**: when a reviewer or other 3rd party makes non-trivial + suggestions for how to change a patch, it is good practice to credit them + by including a ``Suggested-by`` tag. + +Subsystem maintainer requirements +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When a subsystem maintainer accepts a patch from a contributor, in addition to +the normal code review points, they are expected to validate the presence of +suitable ``Signed-off-by`` tags. + +At the time they queue the patch in their subsystem tree, the maintainer +**must** also then add their own ``Signed-off-by`` to indicate that they have +done the aforementioned validation. This is in addition to any of their own +``Reviewed-by`` tags the subsystem maintainer may wish to include. + +When the maintainer modifies the patch after pulling into their tree, they +should record their contribution. This is typically done via a note in the +commit message, just prior to the maintainer's ``Signed-off-by``:: + + Signed-off-by: Cory Contributor <cory.contributor@example.com> + [Comment rephrased for clarity] + Signed-off-by: Mary Maintainer <mary.maintainer@mycorp.test> + + +Tools for adding ``Signed-off-by`` +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are a variety of ways tools can support adding ``Signed-off-by`` tags +for patches, avoiding the need for contributors to manually type in this +repetitive text each time. + +git commands +^^^^^^^^^^^^ + +When creating, or amending, a commit the ``-s`` flag to ``git commit`` will +append a suitable line matching the configured git author details. + +If preparing patches using the ``git format-patch`` tool, the ``-s`` flag can +be used to append a suitable line in the emails it creates, without modifying +the local commits. Alternatively to modify all the local commits on a branch:: + + git rebase master -x 'git commit --amend --no-edit -s' + +emacs +^^^^^ + +In the file ``$HOME/.emacs.d/abbrev_defs`` add: + +.. code:: elisp + + (define-abbrev-table 'global-abbrev-table + '( + ("8rev" "Reviewed-by: YOUR NAME <your@email.addr>" nil 1) + ("8ack" "Acked-by: YOUR NAME <your@email.addr>" nil 1) + ("8test" "Tested-by: YOUR NAME <your@email.addr>" nil 1) + ("8sob" "Signed-off-by: YOUR NAME <your@email.addr>" nil 1) + )) + +with this change, if you type (for example) ``8rev`` followed by ``<space>`` +or ``<enter>`` it will expand to the whole phrase. + +vim +^^^ + +In the file ``$HOME/.vimrc`` add:: + + iabbrev 8rev Reviewed-by: YOUR NAME <your@email.addr> + iabbrev 8ack Acked-by: YOUR NAME <your@email.addr> + iabbrev 8test Tested-by: YOUR NAME <your@email.addr> + iabbrev 8sob Signed-off-by: YOUR NAME <your@email.addr> + +with this change, if you type (for example) ``8rev`` followed by ``<space>`` +or ``<enter>`` it will expand to the whole phrase. + +Re-starting abandoned work +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +For a variety of reasons there are some patches that get submitted to QEMU but +never merged. An unrelated contributor may decide (months or years later) to +continue working from the abandoned patch and re-submit it with extra changes. + +The general principles when picking up abandoned work are: + + * Continue to credit the original author for their work, by maintaining their + original ``Signed-off-by`` + * Indicate where the original patch was obtained from (mailing list, bug + tracker, author's git repo, etc) when sending it for review + * Acknowledge the extra work of the new contributor by including their + ``Signed-off-by`` in the patch in addition to the orignal author's + * Indicate who is responsible for what parts of the patch. This is typically + done via a note in the commit message, just prior to the new contributor's + ``Signed-off-by``:: + + Signed-off-by: Some Person <some.person@example.com> + [Rebased and added support for 'foo'] + Signed-off-by: New Person <new.person@mycorp.test> + +In complicated cases, or if otherwise unsure, ask for advice on the project +mailing list. + +It is also recommended to attempt to contact the original author to let them +know you are interested in taking over their work, in case they still intended +to return to the work, or had any suggestions about the best way to continue. + +Inclusion of generated files +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Files in patches contributed to QEMU are generally expected to be provided +only in the preferred format for making modifications. The implication of +this is that the output of code generators or compilers is usually not +appropriate to contribute to QEMU. + +For reasons of practicality there are some exceptions to this rule, where +generated code is permitted, provided it is also accompanied by the +corresponding preferred source format. This is done where it is impractical +to expect those building QEMU to run the code generation or compilation +process. A non-exhaustive list of examples is: + + * Images: where an bitmap image is created from a vector file it is common + to include the rendered bitmaps at desired resolution(s), since subtle + changes in the rasterization process / tools may affect quality. The + original vector file is expected to accompany any generated bitmaps. + + * Firmware: QEMU includes pre-compiled binary ROMs for a variety of guest + firmwares. When such binary ROMs are contributed, the corresponding source + must also be provided, either directly, or through a git submodule link. + + * Dockerfiles: the majority of the dockerfiles are automatically generated + from a canonical list of build dependencies maintained in tree, together + with the libvirt-ci git submodule link. The generated dockerfiles are + included in tree because it is desirable to be able to directly build + container images from a clean git checkout. + + * eBPF: QEMU includes some generated eBPF machine code, since the required + eBPF compilation tools are not broadly available on all targetted OS + distributions. The corresponding eBPF C code for the binary is also + provided. This is a time-limited exception until the eBPF toolchain is + sufficiently broadly available in distros. + +In all cases above, the existence of generated files must be acknowledged +and justified in the commit that introduces them. + +Tools which perform changes to existing code with deterministic algorithmic +manipulation, driven by user specified inputs, are not generally considered +to be "generators". + +For instance, using Coccinelle to convert code from one pattern to another +pattern, or fixing documentation typos with a spell checker, or transforming +code using sed / awk / etc, are not considered to be acts of code +generation. Where an automated manipulation is performed on code, however, +this should be declared in the commit message. + +At times contributors may use or create scripts/tools to generate an initial +boilerplate code template which is then filled in to produce the final patch. +The output of such a tool would still be considered the "preferred format", +since it is intended to be a foundation for further human authored changes. +Such tools are acceptable to use, provided there is clearly defined copyright +and licensing for their output. Note in particular the caveats applying to AI +content generators below. + +Use of AI content generators +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +TL;DR: + + **Current QEMU project policy is to DECLINE any contributions which are + believed to include or derive from AI generated content. This includes + ChatGPT, Claude, Copilot, Llama and similar tools.** + +The increasing prevalence of AI-assisted software development results in a +number of difficult legal questions and risks for software projects, including +QEMU. Of particular concern is content generated by `Large Language Models +<https://en.wikipedia.org/wiki/Large_language_model>`__ (LLMs). + +The QEMU community requires that contributors certify their patch submissions +are made in accordance with the rules of the `Developer's Certificate of +Origin (DCO) <dco>`. + +To satisfy the DCO, the patch contributor has to fully understand the +copyright and license status of content they are contributing to QEMU. With AI +content generators, the copyright and license status of the output is +ill-defined with no generally accepted, settled legal foundation. + +Where the training material is known, it is common for it to include large +volumes of material under restrictive licensing/copyright terms. Even where +the training material is all known to be under open source licenses, it is +likely to be under a variety of terms, not all of which will be compatible +with QEMU's licensing requirements. + +How contributors could comply with DCO terms (b) or (c) for the output of AI +content generators commonly available today is unclear. The QEMU project is +not willing or able to accept the legal risks of non-compliance. + +The QEMU project thus requires that contributors refrain from using AI content +generators on patches intended to be submitted to the project, and will +decline any contribution if use of AI is either known or suspected. + +This policy does not apply to other uses of AI, such as researching APIs or +algorithms, static analysis, or debugging, provided their output is not to be +included in contributions. + +Examples of tools impacted by this policy includes GitHub's CoPilot, OpenAI's +ChatGPT, Anthropic's Claude, and Meta's Code Llama, and code/content +generation agents which are built on top of such tools. + +This policy may evolve as AI tools mature and the legal situation is +clarifed. In the meanwhile, requests for exceptions to this policy will be +evaluated by the QEMU project on a case by case basis. To be granted an +exception, a contributor will need to demonstrate clarity of the license and +copyright status for the tool's output in relation to its training model and +code, to the satisfaction of the project maintainers. diff --git a/docs/devel/codebase.rst b/docs/devel/codebase.rst index 40273e7..2a31437 100644 --- a/docs/devel/codebase.rst +++ b/docs/devel/codebase.rst @@ -116,7 +116,7 @@ yet, so sometimes the source code is all you have. * `monitor <https://gitlab.com/qemu-project/qemu/-/tree/master/monitor>`_: `Monitor <QEMU monitor>` implementation (HMP & QMP). * `nbd <https://gitlab.com/qemu-project/qemu/-/tree/master/nbd>`_: - QEMU `NBD (Network Block Device) <nbd>` server. + QEMU NBD (Network Block Device) server. * `net <https://gitlab.com/qemu-project/qemu/-/tree/master/net>`_: Network (host) support. * `pc-bios <https://gitlab.com/qemu-project/qemu/-/tree/master/pc-bios>`_: diff --git a/docs/devel/index-process.rst b/docs/devel/index-process.rst index cb7c664..5807752 100644 --- a/docs/devel/index-process.rst +++ b/docs/devel/index-process.rst @@ -13,6 +13,7 @@ Notes about how to interact with the community and how and where to submit patch maintainers style submitting-a-patch + code-provenance trivial-patches stable-process submitting-a-pull-request diff --git a/docs/devel/rust.rst b/docs/devel/rust.rst index 88bdec1..dc8c441 100644 --- a/docs/devel/rust.rst +++ b/docs/devel/rust.rst @@ -37,12 +37,16 @@ output directory (typically ``rust/target/``). A vanilla invocation of Cargo will complain that it cannot find the generated sources, which can be fixed in different ways: -* by using special shorthand targets in the QEMU build directory:: +* by using Makefile targets, provided by Meson, that run ``clippy`` or + ``rustdoc``: make clippy - make rustfmt make rustdoc +A target for ``rustfmt`` is also declared in ``rust/meson.build``: + + make rustfmt + * by invoking ``cargo`` through the Meson `development environment`__ feature:: @@ -50,7 +54,7 @@ which can be fixed in different ways: pyvenv/bin/meson devenv -w ../rust cargo fmt If you are going to use ``cargo`` repeatedly, ``pyvenv/bin/meson devenv`` - will enter a shell where commands like ``cargo clippy`` just work. + will enter a shell where commands like ``cargo fmt`` just work. __ https://mesonbuild.com/Commands.html#devenv @@ -66,41 +70,14 @@ be run via ``meson test`` or ``make``:: make check-rust -Building Rust code with ``--enable-modules`` is not supported yet. +Note that doctests require all ``.o`` files from the build to be available. Supported tools ''''''''''''''' -QEMU supports rustc version 1.63.0 and newer. Notably, the following features +QEMU supports rustc version 1.77.0 and newer. Notably, the following features are missing: -* ``core::ffi`` (1.64.0). Use ``std::os::raw`` and ``std::ffi`` instead. - -* ``cast_mut()``/``cast_const()`` (1.65.0). Use ``as`` instead. - -* "let ... else" (1.65.0). Use ``if let`` instead. This is currently patched - in QEMU's vendored copy of the bilge crate. - -* Generic Associated Types (1.65.0) - -* ``CStr::from_bytes_with_nul()`` as a ``const`` function (1.72.0). - -* "Return position ``impl Trait`` in Traits" (1.75.0, blocker for including - the pinned-init create). - -* ``MaybeUninit::zeroed()`` as a ``const`` function (1.75.0). QEMU's - ``Zeroable`` trait can be implemented without ``MaybeUninit::zeroed()``, - so this would be just a cleanup. - -* ``c"" literals`` (stable in 1.77.0). QEMU provides a ``c_str!()`` macro - to define ``CStr`` constants easily - -* ``offset_of!`` (stable in 1.77.0). QEMU uses ``offset_of!()`` heavily; it - provides a replacement in the ``qemu_api`` crate, but it does not support - lifetime parameters and therefore ``&'a Something`` fields in the struct - may have to be replaced by ``NonNull<Something>``. *Nested* ``offset_of!`` - was only stabilized in Rust 1.82.0, but it is not used. - * inline const expression (stable in 1.79.0), currently worked around with associated constants in the ``FnCall`` trait. @@ -119,18 +96,17 @@ are missing: architecture (VMState). Right now, VMState lacks type safety because it is hard to place the ``VMStateField`` definitions in traits. +* NUL-terminated file names with ``#[track_caller]`` are scheduled for + inclusion as ``#![feature(location_file_nul)]``, but it will be a while + before QEMU can use them. For now, there is special code in + ``util/error.c`` to support non-NUL-terminated file names. + * associated const equality would be nice to have for some users of ``callbacks::FnCall``, but is still experimental. ``ASSERT_IS_SOME`` replaces it. __ https://github.com/rust-lang/rust/pull/125258 -It is expected that QEMU will advance its minimum supported version of -rustc to 1.77.0 as soon as possible; as of January 2025, blockers -for that right now are Debian bookworm and 32-bit MIPS processors. -This unfortunately means that references to statics in constants will -remain an issue. - QEMU also supports version 0.60.x of bindgen, which is missing option ``--generate-cstr``. This option requires version 0.66.x and will be adopted as soon as supporting these older versions is not necessary @@ -152,9 +128,8 @@ QEMU includes four crates: for the ``hw/char/pl011.c`` and ``hw/timer/hpet.c`` files. .. [#issues] The ``pl011`` crate is synchronized with ``hw/char/pl011.c`` - as of commit 02b1f7f61928. The ``hpet`` crate is synchronized as of - commit f32352ff9e. Both are lacking tracing functionality; ``hpet`` - is also lacking support for migration. + as of commit 3e0f118f82. The ``hpet`` crate is synchronized as of + commit 1433e38cc8. Both are lacking tracing functionality. This section explains how to work with them. @@ -184,12 +159,12 @@ module status ``bitops`` complete ``callbacks`` complete ``cell`` stable -``c_str`` complete ``errno`` complete +``error`` stable ``irq`` complete +``log`` proof of concept ``memory`` stable ``module`` complete -``offset_of`` stable ``qdev`` stable ``qom`` stable ``sysbus`` stable @@ -441,7 +416,7 @@ Adding dependencies Generally, the set of dependent crates is kept small. Think twice before adding a new external crate, especially if it comes with a large set of dependencies itself. Sometimes QEMU only needs a small subset of the -functionality; see for example QEMU's ``assertions`` or ``c_str`` modules. +functionality; see for example QEMU's ``assertions`` module. On top of this recommendation, adding external crates to QEMU is a slightly complicated process, mostly due to the need to teach Meson how diff --git a/docs/devel/submitting-a-patch.rst b/docs/devel/submitting-a-patch.rst index 65c6407..f7917b8 100644 --- a/docs/devel/submitting-a-patch.rst +++ b/docs/devel/submitting-a-patch.rst @@ -344,28 +344,9 @@ Patch emails must include a ``Signed-off-by:`` line Your patches **must** include a Signed-off-by: line. This is a hard requirement because it's how you say "I'm legally okay to contribute -this and happy for it to go into QEMU". The process is modelled after -the `Linux kernel -<http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/SubmittingPatches?id=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#n297>`__ -policy. - -If you wrote the patch, make sure your "From:" and "Signed-off-by:" -lines use the same spelling. It's okay if you subscribe or contribute to -the list via more than one address, but using multiple addresses in one -commit just confuses things. If someone else wrote the patch, git will -include a "From:" line in the body of the email (different from your -envelope From:) that will give credit to the correct author; but again, -that author's Signed-off-by: line is mandatory, with the same spelling. - -The name used with "Signed-off-by" does not need to be your legal name, -nor birth name, nor appear on any government ID. It is the identity you -choose to be known by in the community, but should not be anonymous, -nor misrepresent whom you are. - -There are various tooling options for automatically adding these tags -include using ``git commit -s`` or ``git format-patch -s``. For more -information see `SubmittingPatches 1.12 -<http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/SubmittingPatches?id=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#n297>`__. +this and happy for it to go into QEMU". For full guidance, read the +:ref:`code-provenance` documentation. + .. _include_a_meaningful_cover_letter: diff --git a/docs/devel/testing/functional.rst b/docs/devel/testing/functional.rst index 8030cb4..9e56dd1 100644 --- a/docs/devel/testing/functional.rst +++ b/docs/devel/testing/functional.rst @@ -274,7 +274,7 @@ speed mode in the meson.build file, while the "quick" speed mode is fine for functional tests that can be run without downloading files. ``make check`` then only runs the quick functional tests along with the other quick tests from the other test suites. If you choose to -run only run ``make check-functional``, the "thorough" tests will be +run only ``make check-functional``, the "thorough" tests will be executed, too. And to run all functional tests along with the others, you can use something like:: |