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Diffstat (limited to 'Documentation/process/2.Process.rst')
| -rw-r--r-- | Documentation/process/2.Process.rst | 149 |
1 files changed, 71 insertions, 78 deletions
diff --git a/Documentation/process/2.Process.rst b/Documentation/process/2.Process.rst index ae020d84d7c4..7bd41838a546 100644 --- a/Documentation/process/2.Process.rst +++ b/Documentation/process/2.Process.rst @@ -13,24 +13,19 @@ how the process works is required in order to be an effective part of it. The big picture --------------- -The kernel developers use a loosely time-based release process, with a new -major kernel release happening every two or three months. The recent -release history looks like this: - - ====== ================= - 4.11 April 30, 2017 - 4.12 July 2, 2017 - 4.13 September 3, 2017 - 4.14 November 12, 2017 - 4.15 January 28, 2018 - 4.16 April 1, 2018 - ====== ================= - -Every 4.x release is a major kernel release with new features, internal -API changes, and more. A typical 4.x release contain about 13,000 -changesets with changes to several hundred thousand lines of code. 4.x is -thus the leading edge of Linux kernel development; the kernel uses a -rolling development model which is continually integrating major changes. +The Linux kernel uses a loosely time-based, rolling release development +model. A new major kernel release (which we will call, as an example, 9.x) +[1]_ happens every two or three months, which comes with new features, +internal API changes, and more. A typical release can contain about 13,000 +changesets with changes to several hundred thousand lines of code. Recent +releases, along with their dates, can be found at `Wikipedia +<https://en.wikipedia.org/wiki/Linux_kernel_version_history>`_. + +.. [1] Strictly speaking, the Linux kernel does not use semantic versioning + number scheme, but rather the 9.x pair identifies major release + version as a whole number. For each release, x is incremented, + but 9 is incremented only if x is deemed large enough (e.g. + Linux 5.0 is released following Linux 4.20). A relatively straightforward discipline is followed with regard to the merging of patches for each release. At the beginning of each development @@ -48,9 +43,9 @@ detail later on). The merge window lasts for approximately two weeks. At the end of this time, Linus Torvalds will declare that the window is closed and release the -first of the "rc" kernels. For the kernel which is destined to be 2.6.40, +first of the "rc" kernels. For the kernel which is destined to be 9.x, for example, the release which happens at the end of the merge window will -be called 2.6.40-rc1. The -rc1 release is the signal that the time to +be called 9.x-rc1. The -rc1 release is the signal that the time to merge new features has passed, and that the time to stabilize the next kernel has begun. @@ -67,22 +62,23 @@ add at any time). As fixes make their way into the mainline, the patch rate will slow over time. Linus releases new -rc kernels about once a week; a normal series will get up to somewhere between -rc6 and -rc9 before the kernel is -considered to be sufficiently stable and the final 2.6.x release is made. +considered to be sufficiently stable and the final release is made. At that point the whole process starts over again. -As an example, here is how the 4.16 development cycle went (all dates in -2018): +As an example, here is how the 5.4 development cycle went (all dates in +2019): ============== =============================== - January 28 4.15 stable release - February 11 4.16-rc1, merge window closes - February 18 4.16-rc2 - February 25 4.16-rc3 - March 4 4.16-rc4 - March 11 4.16-rc5 - March 18 4.16-rc6 - March 25 4.16-rc7 - April 1 4.16 stable release + September 15 5.3 stable release + September 30 5.4-rc1, merge window closes + October 6 5.4-rc2 + October 13 5.4-rc3 + October 20 5.4-rc4 + October 27 5.4-rc5 + November 3 5.4-rc6 + November 10 5.4-rc7 + November 17 5.4-rc8 + November 24 5.4 stable release ============== =============================== How do the developers decide when to close the development cycle and create @@ -98,43 +94,39 @@ release is made. In the real world, this kind of perfection is hard to achieve; there are just too many variables in a project of this size. There comes a point where delaying the final release just makes the problem worse; the pile of changes waiting for the next merge window will grow -larger, creating even more regressions the next time around. So most 4.x -kernels go out with a handful of known regressions though, hopefully, none -of them are serious. +larger, creating even more regressions the next time around. So most kernels +go out with a handful of known regressions, though, hopefully, none of them +are serious. Once a stable release is made, its ongoing maintenance is passed off to the -"stable team," currently consisting of Greg Kroah-Hartman. The stable team -will release occasional updates to the stable release using the 4.x.y -numbering scheme. To be considered for an update release, a patch must (1) -fix a significant bug, and (2) already be merged into the mainline for the -next development kernel. Kernels will typically receive stable updates for -a little more than one development cycle past their initial release. So, -for example, the 4.13 kernel's history looked like: +"stable team," currently consists of Greg Kroah-Hartman and Sasha Levin. The +stable team will release occasional updates to the stable release using the +9.x.y numbering scheme. + +To be considered for an update release, a patch must (1) fix a significant +bug, and (2) already be merged into the mainline for the next development +kernel. Kernels will typically receive stable updates for a little more +than one development cycle past their initial release. So, for example, the +5.2 kernel's history looked like this (all dates in 2019): ============== =============================== - September 3 4.13 stable release - September 13 4.13.1 - September 20 4.13.2 - September 27 4.13.3 - October 5 4.13.4 - October 12 4.13.5 + July 7 5.2 stable release + July 14 5.2.1 + July 21 5.2.2 + July 26 5.2.3 + July 28 5.2.4 + July 31 5.2.5 ... ... - November 24 4.13.16 + October 11 5.2.21 ============== =============================== -4.13.16 was the final stable update of the 4.13 release. +5.2.21 was the final stable update of the 5.2 release. Some kernels are designated "long term" kernels; they will receive support -for a longer period. As of this writing, the current long term kernels -and their maintainers are: +for a longer period. Please refer to the following link for the list of active +long term kernel versions and their maintainers: - ====== ====================== ============================== - 3.16 Ben Hutchings (very long-term stable kernel) - 4.1 Sasha Levin - 4.4 Greg Kroah-Hartman (very long-term stable kernel) - 4.9 Greg Kroah-Hartman - 4.14 Greg Kroah-Hartman - ====== ====================== ============================== + https://www.kernel.org/category/releases.html The selection of a kernel for long-term support is purely a matter of a maintainer having the need and the time to maintain that release. There @@ -215,12 +207,12 @@ How patches get into the Kernel ------------------------------- There is exactly one person who can merge patches into the mainline kernel -repository: Linus Torvalds. But, of the over 9,500 patches which went -into the 2.6.38 kernel, only 112 (around 1.3%) were directly chosen by Linus -himself. The kernel project has long since grown to a size where no single -developer could possibly inspect and select every patch unassisted. The -way the kernel developers have addressed this growth is through the use of -a lieutenant system built around a chain of trust. +repository: Linus Torvalds. But, for example, of the over 9,500 patches +which went into the 2.6.38 kernel, only 112 (around 1.3%) were directly +chosen by Linus himself. The kernel project has long since grown to a size +where no single developer could possibly inspect and select every patch +unassisted. The way the kernel developers have addressed this growth is +through the use of a lieutenant system built around a chain of trust. The kernel code base is logically broken down into a set of subsystems: networking, specific architecture support, memory management, video @@ -293,7 +285,7 @@ mainline get there via -mm. The current -mm patch is available in the "mmotm" (-mm of the moment) directory at: - http://www.ozlabs.org/~akpm/mmotm/ + https://www.ozlabs.org/~akpm/mmotm/ Use of the MMOTM tree is likely to be a frustrating experience, though; there is a definite chance that it will not even compile. @@ -304,7 +296,7 @@ the mainline is expected to look like after the next merge window closes. Linux-next trees are announced on the linux-kernel and linux-next mailing lists when they are assembled; they can be downloaded from: - http://www.kernel.org/pub/linux/kernel/next/ + https://www.kernel.org/pub/linux/kernel/next/ Linux-next has become an integral part of the kernel development process; all patches merged during a given merge window should really have found @@ -363,21 +355,21 @@ to keep up with what other developers (and the mainline) are doing. Git is now packaged by almost all Linux distributions. There is a home page at: - http://git-scm.com/ + https://git-scm.com/ That page has pointers to documentation and tutorials. Among the kernel developers who do not use git, the most popular choice is almost certainly Mercurial: - http://www.selenic.com/mercurial/ + https://www.selenic.com/mercurial/ Mercurial shares many features with git, but it provides an interface which many find easier to use. The other tool worth knowing about is Quilt: - http://savannah.nongnu.org/projects/quilt/ + https://savannah.nongnu.org/projects/quilt/ Quilt is a patch management system, rather than a source code management system. It does not track history over time; it is, instead, oriented @@ -397,13 +389,13 @@ represent a potential hazard to developers, who risk getting buried under a load of electronic mail, running afoul of the conventions used on the Linux lists, or both. -Most kernel mailing lists are run on vger.kernel.org; the master list can +Most kernel mailing lists are hosted at kernel.org; the master list can be found at: - http://vger.kernel.org/vger-lists.html + https://subspace.kernel.org -There are lists hosted elsewhere, though; a number of them are at -lists.redhat.com. +There are lists hosted elsewhere; please check the MAINTAINERS file for +the list relevant for any particular subsystem. The core mailing list for kernel development is, of course, linux-kernel. This list is an intimidating place to be; volume can reach 500 messages per @@ -439,9 +431,10 @@ 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 @@ -492,7 +485,7 @@ Andrew Morton gives this advice for aspiring kernel developers with others on getting things fixed up (this can require persistence!) but that's fine - it's a part of kernel development. -(http://lwn.net/Articles/283982/). +(https://lwn.net/Articles/283982/). In the absence of obvious problems to fix, developers are advised to look at the current lists of regressions and open bugs in general. There is |