@@ -18,18 +18,18 @@ major kernel release happening every two or three months. The recent
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release history looks like this:
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====== =================
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- 4.11 April 30, 2017
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- 4.12 July 2, 2017
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- 4.13 September 3, 2017
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- 4.14 November 12, 2017
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- 4.15 January 28, 2018
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- 4.16 April 1, 2018
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+ 5.0 March 3, 2019
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+ 5.1 May 5, 2019
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+ 5.2 July 7, 2019
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+ 5.3 September 15, 2019
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+ 5.4 November 24, 2019
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+ 5.5 January 6, 2020
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====== =================
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- Every 4 .x release is a major kernel release with new features, internal
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- API changes, and more. A typical 4.x release contain about 13,000
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- changesets with changes to several hundred thousand lines of code. 4 .x is
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- thus the leading edge of Linux kernel development; the kernel uses a
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+ Every 5 .x release is a major kernel release with new features, internal
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+ API changes, and more. A typical release can contain about 13,000
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+ changesets with changes to several hundred thousand lines of code. 5 .x is
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+ the leading edge of Linux kernel development; the kernel uses a
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rolling development model which is continually integrating major changes.
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A relatively straightforward discipline is followed with regard to the
@@ -48,9 +48,9 @@ detail later on).
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The merge window lasts for approximately two weeks. At the end of this
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time, Linus Torvalds will declare that the window is closed and release the
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- first of the "rc" kernels. For the kernel which is destined to be 2.6.40 ,
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+ first of the "rc" kernels. For the kernel which is destined to be 5.6 ,
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for example, the release which happens at the end of the merge window will
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- be called 2.6.40 -rc1. The -rc1 release is the signal that the time to
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+ be called 5.6 -rc1. The -rc1 release is the signal that the time to
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merge new features has passed, and that the time to stabilize the next
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kernel has begun.
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@@ -67,22 +67,23 @@ add at any time).
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As fixes make their way into the mainline, the patch rate will slow over
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time. Linus releases new -rc kernels about once a week; a normal series
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will get up to somewhere between -rc6 and -rc9 before the kernel is
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- considered to be sufficiently stable and the final 2.6.x release is made.
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+ considered to be sufficiently stable and the final release is made.
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At that point the whole process starts over again.
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- As an example, here is how the 4.16 development cycle went (all dates in
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- 2018 ):
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+ As an example, here is how the 5.4 development cycle went (all dates in
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+ 2019 ):
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============== ===============================
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- January 28 4.15 stable release
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- February 11 4.16-rc1, merge window closes
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- February 18 4.16-rc2
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- February 25 4.16-rc3
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- March 4 4.16-rc4
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- March 11 4.16-rc5
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- March 18 4.16-rc6
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- March 25 4.16-rc7
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- April 1 4.16 stable release
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+ September 15 5.3 stable release
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+ September 30 5.4-rc1, merge window closes
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+ October 6 5.4-rc2
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+ October 13 5.4-rc3
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+ October 20 5.4-rc4
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+ October 27 5.4-rc5
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+ November 3 5.4-rc6
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+ November 10 5.4-rc7
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+ November 17 5.4-rc8
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+ November 24 5.4 stable release
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============== ===============================
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How do the developers decide when to close the development cycle and create
@@ -98,43 +99,44 @@ release is made. In the real world, this kind of perfection is hard to
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achieve; there are just too many variables in a project of this size.
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There comes a point where delaying the final release just makes the problem
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worse; the pile of changes waiting for the next merge window will grow
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- larger, creating even more regressions the next time around. So most 4 .x
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+ larger, creating even more regressions the next time around. So most 5 .x
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kernels go out with a handful of known regressions though, hopefully, none
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of them are serious.
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Once a stable release is made, its ongoing maintenance is passed off to the
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- "stable team," currently consisting of Greg Kroah-Hartman. The stable team
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- will release occasional updates to the stable release using the 4 .x.y
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- numbering scheme. To be considered for an update release, a patch must (1)
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- fix a significant bug, and (2) already be merged into the mainline for the
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- next development kernel. Kernels will typically receive stable updates for
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- a little more than one development cycle past their initial release. So,
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- for example, the 4.13 kernel's history looked like:
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+ "stable team," currently Greg Kroah-Hartman. The stable team will release
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+ occasional updates to the stable release using the 5 .x.y numbering scheme.
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+ To be considered for an update release, a patch must (1) fix a significant
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+ bug, and (2) already be merged into the mainline for the next development
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+ kernel. Kernels will typically receive stable updates for a little more
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+ than one development cycle past their initial release. So, for example, the
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+ 5.2 kernel's history looked like this (all dates in 2019) :
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============== ===============================
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- September 3 4.13 stable release
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- September 13 4.13 .1
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- September 20 4.13 .2
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- September 27 4.13 .3
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- October 5 4.13 .4
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- October 12 4.13 .5
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+ September 15 5.2 stable release
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+ July 14 5.2 .1
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+ July 21 5.2 .2
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+ July 26 5.2 .3
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+ July 28 5.2 .4
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+ July 31 5.2 .5
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... ...
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- November 24 4.13.16
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+ October 11 5.2.21
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============== ===============================
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- 4.13.16 was the final stable update of the 4.13 release.
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+ 5.2.21 was the final stable update of the 5.2 release.
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Some kernels are designated "long term" kernels; they will receive support
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for a longer period. As of this writing, the current long term kernels
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and their maintainers are:
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- ====== ====================== ==============================
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- 3.16 Ben Hutchings (very long-term stable kernel)
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- 4.1 Sasha Levin
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- 4.4 Greg Kroah-Hartman (very long-term stable kernel)
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- 4.9 Greg Kroah-Hartman
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- 4.14 Greg Kroah-Hartman
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- ====== ====================== ==============================
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+ ====== ================================ =======================
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+ 3.16 Ben Hutchings (very long-term kernel)
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+ 4.4 Greg Kroah-Hartman & Sasha Levin (very long-term kernel)
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+ 4.9 Greg Kroah-Hartman & Sasha Levin
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+ 4.14 Greg Kroah-Hartman & Sasha Levin
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+ 4.19 Greg Kroah-Hartman & Sasha Levin
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+ 5.4 Greg Kroah-Hartman & Sasha Levin
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+ ====== ================================ =======================
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The selection of a kernel for long-term support is purely a matter of a
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maintainer having the need and the time to maintain that release. There
@@ -215,12 +217,12 @@ How patches get into the Kernel
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-------------------------------
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There is exactly one person who can merge patches into the mainline kernel
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- repository: Linus Torvalds. But, of the over 9,500 patches which went
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- into the 2.6.38 kernel, only 112 (around 1.3%) were directly chosen by Linus
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- himself. The kernel project has long since grown to a size where no single
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- developer could possibly inspect and select every patch unassisted. The
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- way the kernel developers have addressed this growth is through the use of
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- a lieutenant system built around a chain of trust.
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+ repository: Linus Torvalds. But, for example, of the over 9,500 patches
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+ which went into the 2.6.38 kernel, only 112 (around 1.3%) were directly
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+ chosen by Linus himself. The kernel project has long since grown to a size
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+ where no single developer could possibly inspect and select every patch
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+ unassisted. The way the kernel developers have addressed this growth is
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+ through the use of a lieutenant system built around a chain of trust.
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The kernel code base is logically broken down into a set of subsystems:
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networking, specific architecture support, memory management, video
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