diff options
Diffstat (limited to 'Documentation/process')
| -rw-r--r-- | Documentation/process/2.Process.rst | 7 | ||||
| -rw-r--r-- | Documentation/process/changes.rst | 16 | ||||
| -rw-r--r-- | Documentation/process/handling-regressions.rst | 208 | ||||
| -rw-r--r-- | Documentation/process/maintainer-handbooks.rst | 3 | ||||
| -rw-r--r-- | Documentation/process/maintainer-soc.rst | 177 | ||||
| -rw-r--r-- | Documentation/process/maintainer-tip.rst | 3 | ||||
| -rw-r--r-- | Documentation/process/submitting-patches.rst | 25 |
7 files changed, 352 insertions, 87 deletions
diff --git a/Documentation/process/2.Process.rst b/Documentation/process/2.Process.rst index 6a919cffcbfd..613a01da4717 100644 --- a/Documentation/process/2.Process.rst +++ b/Documentation/process/2.Process.rst @@ -434,9 +434,10 @@ There are a few hints which can help with linux-kernel survival: questions. Some developers can get impatient with people who clearly have not done their homework. -- Avoid top-posting (the practice of putting your answer above the quoted - text you are responding to). It makes your response harder to read and - makes a poor impression. +- Use interleaved ("inline") replies, which makes your response easier to + read. (i.e. avoid top-posting -- the practice of putting your answer above + the quoted text you are responding to.) For more details, see + :ref:`Documentation/process/submitting-patches.rst <interleaved_replies>`. - Ask on the correct mailing list. Linux-kernel may be the general meeting point, but it is not the best place to find developers from all diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst index ef540865ad22..5561dae94f85 100644 --- a/Documentation/process/changes.rst +++ b/Documentation/process/changes.rst @@ -31,7 +31,7 @@ you probably needn't concern yourself with pcmciautils. ====================== =============== ======================================== GNU C 5.1 gcc --version Clang/LLVM (optional) 11.0.0 clang --version -Rust (optional) 1.62.0 rustc --version +Rust (optional) 1.68.2 rustc --version bindgen (optional) 0.56.0 bindgen --version GNU make 3.82 make --version bash 4.2 bash --version @@ -60,6 +60,8 @@ openssl & libcrypto 1.0.0 openssl version bc 1.06.95 bc --version Sphinx\ [#f1]_ 1.7 sphinx-build --version cpio any cpio --version +GNU tar 1.28 tar --version +gtags (optional) 6.6.5 gtags --version ====================== =============== ======================================== .. [#f1] Sphinx is needed only to build the Kernel documentation @@ -174,6 +176,18 @@ You will need openssl to build kernels 3.7 and higher if module signing is enabled. You will also need openssl development packages to build kernels 4.3 and higher. +Tar +--- + +GNU tar is needed if you want to enable access to the kernel headers via sysfs +(CONFIG_IKHEADERS). + +gtags / GNU GLOBAL (optional) +----------------------------- + +The kernel build requires GNU GLOBAL version 6.6.5 or later to generate +tag files through ``make gtags``. This is due to its use of the gtags +``-C (--directory)`` flag. System utilities **************** diff --git a/Documentation/process/handling-regressions.rst b/Documentation/process/handling-regressions.rst index abb741b1aeee..5d3c3de3f4ec 100644 --- a/Documentation/process/handling-regressions.rst +++ b/Documentation/process/handling-regressions.rst @@ -129,88 +129,132 @@ tools and scripts used by other kernel developers or Linux distributions; one of these tools is regzbot, which heavily relies on the "Link:" tags to associate reports for regression with changes resolving them. -Prioritize work on fixing regressions -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -You should fix any reported regression as quickly as possible, to provide -affected users with a solution in a timely manner and prevent more users from -running into the issue; nevertheless developers need to take enough time and -care to ensure regression fixes do not cause additional damage. - -In the end though, developers should give their best to prevent users from -running into situations where a regression leaves them only three options: "run -a kernel with a regression that seriously impacts usage", "continue running an -outdated and thus potentially insecure kernel version for more than two weeks -after a regression's culprit was identified", and "downgrade to a still -supported kernel series that lack required features". - -How to realize this depends a lot on the situation. Here are a few rules of -thumb for you, in order or importance: - - * Prioritize work on handling regression reports and fixing regression over all - other Linux kernel work, unless the latter concerns acute security issues or - bugs causing data loss or damage. - - * Always consider reverting the culprit commits and reapplying them later - together with necessary fixes, as this might be the least dangerous and - quickest way to fix a regression. - - * Developers should handle regressions in all supported kernel series, but are - free to delegate the work to the stable team, if the issue probably at no - point in time occurred with mainline. - - * Try to resolve any regressions introduced in the current development before - its end. If you fear a fix might be too risky to apply only days before a new - mainline release, let Linus decide: submit the fix separately to him as soon - as possible with the explanation of the situation. He then can make a call - and postpone the release if necessary, for example if multiple such changes - show up in his inbox. - - * Address regressions in stable, longterm, or proper mainline releases with - more urgency than regressions in mainline pre-releases. That changes after - the release of the fifth pre-release, aka "-rc5": mainline then becomes as - important, to ensure all the improvements and fixes are ideally tested - together for at least one week before Linus releases a new mainline version. - - * Fix regressions within two or three days, if they are critical for some - reason -- for example, if the issue is likely to affect many users of the - kernel series in question on all or certain architectures. Note, this - includes mainline, as issues like compile errors otherwise might prevent many - testers or continuous integration systems from testing the series. - - * Aim to fix regressions within one week after the culprit was identified, if - the issue was introduced in either: - - * a recent stable/longterm release - - * the development cycle of the latest proper mainline release - - In the latter case (say Linux v5.14), try to address regressions even - quicker, if the stable series for the predecessor (v5.13) will be abandoned - soon or already was stamped "End-of-Life" (EOL) -- this usually happens about - three to four weeks after a new mainline release. - - * Try to fix all other regressions within two weeks after the culprit was - found. Two or three additional weeks are acceptable for performance - regressions and other issues which are annoying, but don't prevent anyone - from running Linux (unless it's an issue in the current development cycle, - as those should ideally be addressed before the release). A few weeks in - total are acceptable if a regression can only be fixed with a risky change - and at the same time is affecting only a few users; as much time is - also okay if the regression is already present in the second newest longterm - kernel series. - -Note: The aforementioned time frames for resolving regressions are meant to -include getting the fix tested, reviewed, and merged into mainline, ideally with -the fix being in linux-next at least briefly. This leads to delays you need to -account for. - -Subsystem maintainers are expected to assist in reaching those periods by doing -timely reviews and quick handling of accepted patches. They thus might have to -send git-pull requests earlier or more often than usual; depending on the fix, -it might even be acceptable to skip testing in linux-next. Especially fixes for -regressions in stable and longterm kernels need to be handled quickly, as fixes -need to be merged in mainline before they can be backported to older series. +Expectations and best practices for fixing regressions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +As a Linux kernel developer, you are expected to give your best to prevent +situations where a regression caused by a recent change of yours leaves users +only these options: + + * Run a kernel with a regression that impacts usage. + + * Switch to an older or newer kernel series. + + * Continue running an outdated and thus potentially insecure kernel for more + than three weeks after the regression's culprit was identified. Ideally it + should be less than two. And it ought to be just a few days, if the issue is + severe or affects many users -- either in general or in prevalent + environments. + +How to realize that in practice depends on various factors. Use the following +rules of thumb as a guide. + +In general: + + * Prioritize work on regressions over all other Linux kernel work, unless the + latter concerns a severe issue (e.g. acute security vulnerability, data loss, + bricked hardware, ...). + + * Expedite fixing mainline regressions that recently made it into a proper + mainline, stable, or longterm release (either directly or via backport). + + * Do not consider regressions from the current cycle as something that can wait + till the end of the cycle, as the issue might discourage or prevent users and + CI systems from testing mainline now or generally. + + * Work with the required care to avoid additional or bigger damage, even if + resolving an issue then might take longer than outlined below. + +On timing once the culprit of a regression is known: + + * Aim to mainline a fix within two or three days, if the issue is severe or + bothering many users -- either in general or in prevalent conditions like a + particular hardware environment, distribution, or stable/longterm series. + + * Aim to mainline a fix by Sunday after the next, if the culprit made it + into a recent mainline, stable, or longterm release (either directly or via + backport); if the culprit became known early during a week and is simple to + resolve, try to mainline the fix within the same week. + + * For other regressions, aim to mainline fixes before the hindmost Sunday + within the next three weeks. One or two Sundays later are acceptable, if the + regression is something people can live with easily for a while -- like a + mild performance regression. + + * It's strongly discouraged to delay mainlining regression fixes till the next + merge window, except when the fix is extraordinarily risky or when the + culprit was mainlined more than a year ago. + +On procedure: + + * Always consider reverting the culprit, as it's often the quickest and least + dangerous way to fix a regression. Don't worry about mainlining a fixed + variant later: that should be straight-forward, as most of the code went + through review once already. + + * Try to resolve any regressions introduced in mainline during the past + twelve months before the current development cycle ends: Linus wants such + regressions to be handled like those from the current cycle, unless fixing + bears unusual risks. + + * Consider CCing Linus on discussions or patch review, if a regression seems + tangly. Do the same in precarious or urgent cases -- especially if the + subsystem maintainer might be unavailable. Also CC the stable team, when you + know such a regression made it into a mainline, stable, or longterm release. + + * For urgent regressions, consider asking Linus to pick up the fix straight + from the mailing list: he is totally fine with that for uncontroversial + fixes. Ideally though such requests should happen in accordance with the + subsystem maintainers or come directly from them. + + * In case you are unsure if a fix is worth the risk applying just days before + a new mainline release, send Linus a mail with the usual lists and people in + CC; in it, summarize the situation while asking him to consider picking up + the fix straight from the list. He then himself can make the call and when + needed even postpone the release. Such requests again should ideally happen + in accordance with the subsystem maintainers or come directly from them. + +Regarding stable and longterm kernels: + + * You are free to leave regressions to the stable team, if they at no point in + time occurred with mainline or were fixed there already. + + * If a regression made it into a proper mainline release during the past + twelve months, ensure to tag the fix with "Cc: stable@vger.kernel.org", as a + "Fixes:" tag alone does not guarantee a backport. Please add the same tag, + in case you know the culprit was backported to stable or longterm kernels. + + * When receiving reports about regressions in recent stable or longterm kernel + series, please evaluate at least briefly if the issue might happen in current + mainline as well -- and if that seems likely, take hold of the report. If in + doubt, ask the reporter to check mainline. + + * Whenever you want to swiftly resolve a regression that recently also made it + into a proper mainline, stable, or longterm release, fix it quickly in + mainline; when appropriate thus involve Linus to fast-track the fix (see + above). That's because the stable team normally does neither revert nor fix + any changes that cause the same problems in mainline. + + * In case of urgent regression fixes you might want to ensure prompt + backporting by dropping the stable team a note once the fix was mainlined; + this is especially advisable during merge windows and shortly thereafter, as + the fix otherwise might land at the end of a huge patch queue. + +On patch flow: + + * Developers, when trying to reach the time periods mentioned above, remember + to account for the time it takes to get fixes tested, reviewed, and merged by + Linus, ideally with them being in linux-next at least briefly. Hence, if a + fix is urgent, make it obvious to ensure others handle it appropriately. + + * Reviewers, you are kindly asked to assist developers in reaching the time + periods mentioned above by reviewing regression fixes in a timely manner. + + * Subsystem maintainers, you likewise are encouraged to expedite the handling + of regression fixes. Thus evaluate if skipping linux-next is an option for + the particular fix. Also consider sending git pull requests more often than + usual when needed. And try to avoid holding onto regression fixes over + weekends -- especially when the fix is marked for backporting. More aspects regarding regressions developers should be aware of diff --git a/Documentation/process/maintainer-handbooks.rst b/Documentation/process/maintainer-handbooks.rst index d12cbbe2b7df..9992bfd7eaa3 100644 --- a/Documentation/process/maintainer-handbooks.rst +++ b/Documentation/process/maintainer-handbooks.rst @@ -15,6 +15,7 @@ Contents: :numbered: :maxdepth: 2 - maintainer-tip maintainer-netdev + maintainer-soc + maintainer-tip maintainer-kvm-x86 diff --git a/Documentation/process/maintainer-soc.rst b/Documentation/process/maintainer-soc.rst new file mode 100644 index 000000000000..49f08289d62c --- /dev/null +++ b/Documentation/process/maintainer-soc.rst @@ -0,0 +1,177 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============= +SoC Subsystem +============= + +Overview +-------- + +The SoC subsystem is a place of aggregation for SoC-specific code. +The main components of the subsystem are: + +* devicetrees for 32- & 64-bit ARM and RISC-V +* 32-bit ARM board files (arch/arm/mach*) +* 32- & 64-bit ARM defconfigs +* SoC-specific drivers across architectures, in particular for 32- & 64-bit + ARM, RISC-V and Loongarch + +These "SoC-specific drivers" do not include clock, GPIO etc drivers that have +other top-level maintainers. The drivers/soc/ directory is generally meant +for kernel-internal drivers that are used by other drivers to provide SoC- +specific functionality like identifying an SoC revision or interfacing with +power domains. + +The SoC subsystem also serves as an intermediate location for changes to +drivers/bus, drivers/firmware, drivers/reset and drivers/memory. The addition +of new platforms, or the removal of existing ones, often go through the SoC +tree as a dedicated branch covering multiple subsystems. + +The main SoC tree is housed on git.kernel.org: + https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git/ + +Clearly this is quite a wide range of topics, which no one person, or even +small group of people are capable of maintaining. Instead, the SoC subsystem +is comprised of many submaintainers, each taking care of individual platforms +and driver subdirectories. +In this regard, "platform" usually refers to a series of SoCs from a given +vendor, for example, Nvidia's series of Tegra SoCs. Many submaintainers operate +on a vendor level, responsible for multiple product lines. For several reasons, +including acquisitions/different business units in a company, things vary +significantly here. The various submaintainers are documented in the +MAINTAINERS file. + +Most of these submaintainers have their own trees where they stage patches, +sending pull requests to the main SoC tree. These trees are usually, but not +always, listed in MAINTAINERS. The main SoC maintainers can be reached via the +alias soc@kernel.org if there is no platform-specific maintainer, or if they +are unresponsive. + +What the SoC tree is not, however, is a location for architecture-specific code +changes. Each architecture has its own maintainers that are responsible for +architectural details, CPU errata and the like. + +Information for (new) Submaintainers +------------------------------------ + +As new platforms spring up, they often bring with them new submaintainers, +many of whom work for the silicon vendor, and may not be familiar with the +process. + +Devicetree ABI Stability +~~~~~~~~~~~~~~~~~~~~~~~~ + +Perhaps one of the most important things to highlight is that dt-bindings +document the ABI between the devicetree and the kernel. +Please read Documentation/devicetree/bindings/ABI.rst. + +If changes are being made to a devicetree that are incompatible with old +kernels, the devicetree patch should not be applied until the driver is, or an +appropriate time later. Most importantly, any incompatible changes should be +clearly pointed out in the patch description and pull request, along with the +expected impact on existing users, such as bootloaders or other operating +systems. + +Driver Branch Dependencies +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +A common problem is synchronizing changes between device drivers and devicetree +files. Even if a change is compatible in both directions, this may require +coordinating how the changes get merged through different maintainer trees. + +Usually the branch that includes a driver change will also include the +corresponding change to the devicetree binding description, to ensure they are +in fact compatible. This means that the devicetree branch can end up causing +warnings in the "make dtbs_check" step. If a devicetree change depends on +missing additions to a header file in include/dt-bindings/, it will fail the +"make dtbs" step and not get merged. + +There are multiple ways to deal with this: + +* Avoid defining custom macros in include/dt-bindings/ for hardware constants + that can be derived from a datasheet -- binding macros in header files should + only be used as a last resort if there is no natural way to define a binding + +* Use literal values in the devicetree file in place of macros even when a + header is required, and change them to the named representation in a + following release + +* Defer the devicetree changes to a release after the binding and driver have + already been merged + +* Change the bindings in a shared immutable branch that is used as the base for + both the driver change and the devicetree changes + +* Add duplicate defines in the devicetree file guarded by an #ifndef section, + removing them in a later release + +Devicetree Naming Convention +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The general naming scheme for devicetree files is as follows. The aspects of a +platform that are set at the SoC level, like CPU cores, are contained in a file +named $soc.dtsi, for example, jh7100.dtsi. Integration details, that will vary +from board to board, are described in $soc-$board.dts. An example of this is +jh7100-beaglev-starlight.dts. Often many boards are variations on a theme, and +frequently there are intermediate files, such as jh7100-common.dtsi, which sit +between the $soc.dtsi and $soc-$board.dts files, containing the descriptions of +common hardware. + +Some platforms also have System on Modules, containing an SoC, which are then +integrated into several different boards. For these platforms, $soc-$som.dtsi +and $soc-$som-$board.dts are typical. + +Directories are usually named after the vendor of the SoC at the time of its +inclusion, leading to some historical directory names in the tree. + +Validating Devicetree Files +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +``make dtbs_check`` can be used to validate that devicetree files are compliant +with the dt-bindings that describe the ABI. Please read the section +"Running checks" of Documentation/devicetree/bindings/writing-schema.rst for +more information on the validation of devicetrees. + +For new platforms, or additions to existing ones, ``make dtbs_check`` should not +add any new warnings. For RISC-V, as it has the advantage of being a newer +architecture, ``make dtbs_check W=1`` is required to not add any new warnings. +If in any doubt about a devicetree change, reach out to the devicetree +maintainers. + +Branches and Pull Requests +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Just as the main SoC tree has several branches, it is expected that +submaintainers will do the same. Driver, defconfig and devicetree changes should +all be split into separate branches and appear in separate pull requests to the +SoC maintainers. Each branch should be usable by itself and avoid +regressions that originate from dependencies on other branches. + +Small sets of patches can also be sent as separate emails to soc@kernel.org, +grouped into the same categories. + +If changes do not fit into the normal patterns, there can be additional +top-level branches, e.g. for a treewide rework, or the addition of new SoC +platforms including dts files and drivers. + +Branches with a lot of changes can benefit from getting split up into separate +topics branches, even if they end up getting merged into the same branch of the +SoC tree. An example here would be one branch for devicetree warning fixes, one +for a rework and one for newly added boards. + +Another common way to split up changes is to send an early pull request with the +majority of the changes at some point between rc1 and rc4, following up with one +or more smaller pull requests towards the end of the cycle that can add late +changes or address problems identified while testing the first set. + +While there is no cut-off time for late pull requests, it helps to only send +small branches as time gets closer to the merge window. + +Pull requests for bugfixes for the current release can be sent at any time, but +again having multiple smaller branches is better than trying to combine too many +patches into one pull request. + +The subject line of a pull request should begin with "[GIT PULL]" and made using +a signed tag, rather than a branch. This tag should contain a short description +summarising the changes in the pull request. For more detail on sending pull +requests, please see Documentation/maintainer/pull-requests.rst. diff --git a/Documentation/process/maintainer-tip.rst b/Documentation/process/maintainer-tip.rst index 0cac75a86372..08dd0f804410 100644 --- a/Documentation/process/maintainer-tip.rst +++ b/Documentation/process/maintainer-tip.rst @@ -421,6 +421,9 @@ allowing themselves a breath. Please respect that. The release candidate -rc1 is the starting point for new patches to be applied which are targeted for the next merge window. +So called _urgent_ branches will be merged into mainline during the +stabilization phase of each release. + Git ^^^ diff --git a/Documentation/process/submitting-patches.rst b/Documentation/process/submitting-patches.rst index 486875fd73c0..efac910e2659 100644 --- a/Documentation/process/submitting-patches.rst +++ b/Documentation/process/submitting-patches.rst @@ -331,6 +331,31 @@ explaining difference against previous submission (see See Documentation/process/email-clients.rst for recommendations on email clients and mailing list etiquette. +.. _interleaved_replies: + +Use trimmed interleaved replies in email discussions +---------------------------------------------------- +Top-posting is strongly discouraged in Linux kernel development +discussions. Interleaved (or "inline") replies make conversations much +easier to follow. For more details see: +https://en.wikipedia.org/wiki/Posting_style#Interleaved_style + +As is frequently quoted on the mailing list:: + + A: http://en.wikipedia.org/wiki/Top_post + Q: Were do I find info about this thing called top-posting? + A: Because it messes up the order in which people normally read text. + Q: Why is top-posting such a bad thing? + A: Top-posting. + Q: What is the most annoying thing in e-mail? + +Similarly, please trim all unneeded quotations that aren't relevant +to your reply. This makes responses easier to find, and saves time and +space. For more details see: http://daringfireball.net/2007/07/on_top :: + + A: No. + Q: Should I include quotations after my reply? + .. _resend_reminders: Don't get discouraged - or impatient |