LTS
The acronym LTS stands for "Long Term Stable", and it refers to kernel versions that have bugfixes and security fixes applied to them, after their initial release.
This page has information about LTS kernels and LTS maintenance.
LTS kernel versions
Multiple groups and organizations maintain kernels, including the upstream kernel community, distribution vendors, and various other projects in the Linux ecosystem.
Upstream Kernel Community
See https://kernel.org/ and https://kernel.org/category/releases.html for the current upstream-supported LTS kernel versions.
As of May 2024, the upstream kernel community supported the following LTS kernel versions:
- 4.19, 5.4, 5.10, 5.15, 6.1, 6.6
Other efforts
- Civil Infrastructure Platform
- CIP plans to support SLTS (Super Long Term Stable) kernel versions for 10 years
- see https://wiki.linuxfoundation.org/civilinfrastructureplatform/start for supported kernel versions
- As of May 2024, CIP supports the following SLTS kernel versions: 4.4, 4.19, 5.10, 6.1 (and rt versions)
- The OpenELA = Open Enterprise Linux Association announced that they planned to do long-term support for the 4.14 kernel
Table of LTS versions
| Kernel Version | Supporting Org | Origin date | End of support date | Maintainer |
| 3.4 | kernel community | 2012-05-20 | 2017-04 | None - last was Li Zefan |
| 3.10 | kernel community | 2013-06-30 | 2017-10 | None - last was Willy Tarreau |
| 3.16 | kernel community | 2014-08-03 | 2020-04 | None - last was Ben Hutchins |
| 4.1 | kernel community | 2015-06-21 | 2017-09 | None - last was Sasha Levin |
| 4.4 | CIP | 2016-01-10 | 2027-01 | Ulrich Hecht |
| 4.4-rt | CIP | 2016-01 | 2027-01 | Pavel Machek |
| 4.9 | kernel community | 2017-02-19 | 2023-01 | None -last was Greg Kroah-Hartman & Sasha Levin |
| 4.14 | kernel community | 2017-02-19 | 2024-01 | None - last was Greg Kroah-Hartman & Sasha Levin |
| 4.14 | OpenELA | 2017-11-12 | ?? | ?? |
| 4.19 | kernel community | 2018-10-22 | 2024-12 | Greg Kroah-Hartman & Sash Levin |
| 4.19 | CIP | 2018-10-22 | 2029-01 | Nobuhiro Iwamatsu & Pavel Machek |
| 4.19-rt | CIP | 2018-10 | 2029-01 | Pavel Machek |
| 5.4 | kernel community | 2019-11-24 | 2025-12 | Greg Kroah-Hartman & Sash Levin |
| 5.10 | kernel community | 2020-12-13 | 2026-12 | Greg Kroah-Hartman & Sash Levin |
| 5.10 | CIP | 2020-12-13 | 2031-01 | Nobuhiro Iwamatsu & Pavel Machek |
| 5.10-rt | CIP | 2020-12-13 | 2031-01 | Pavel Machek |
| 5.15 | kernel community | 2021-10-31 | 2026-12 | Greg Kroah-Hartman & Sash Levin |
| 6.1 | kernel community | 2022-12-11 | 2026-12 | Greg Kroah-Hartman & Sash Levin |
| 6.1 | CIP | 2022-12-11 | 2033-08 | Nobuhiro Iwamatsu & Pavel Machek |
| 6.1 | CIP | 2021-12-11 | 2033-08 | Pavel Machek |
| 6.6 | kernel community | 2023-10-29 | 2026-12 | Greg Kroah-Hartman & Sash Levin |
Analysis
In 2024, a group from UC Riverside Unversity published a paper called "An Investigation of Patch Porting Practices of the Linux Kernel Ecosystem". This paper was presented at the "Mining Software Repositories" conference, in April 2024.
Here is the paper: https://arxiv.org/pdf/2402.05212v1
Tools
Sash Levin, who has been maintaining LTS kernels since at least 2016, has several tools that he uses to help automate the task of selecting and applying commits to use in LTS kernels. See https://git.kernel.org/pub/scm/linux/kernel/git/sashal/stable-tools.git/
An LWN.net article from 2016, based on a talk that Sasha gave at LinuxCon North America 2016, has details about his patch methods and his automation tools. See "Automating stable-kernel creation"