The Linux kernel release cycle uses a structured x.y.z versioning system with three distinct tracks: mainline, stable, and long-term support (LTS). This framework balances rapid feature development with production stability, per official kernel project documentation Linux kernel project. The system is governed by publicly documented release policies, maintained by a global community of thousands of maintainers and contributors from hundreds of organizations, including major technology firms and open source foundations.
Real-world production systems built on this framework include consumer on-device AI workloads such as Google’s Gemini Nano, which expanded to US users in 2026 Google. Embedded smart displays running Samsung’s Art Store rely on the kernel’s release structure for consistent performance, specifically running on the 5.15 LTS kernel branch to minimize downtime for end users Samsung News.
Open source organizations such as Mozilla, which announced its new independent non-profit status in 2026, use the release cycle to validate custom patches before global infrastructure rollouts Mozilla. Understanding this system helps developers and operators plan upgrades, avoid compatibility issues, and align maintenance windows with support timelines for both short-term projects and multi-year infrastructure deployments.
Mainline Kernel Development Workflow
Mainline kernel releases follow a two-phase development workflow managed by the kernel’s maintainer hierarchy, as documented in the project’s official release process guidelines kernel.org.
2-Week Merge Window for Code Integration
The first phase is the merge window, which lasts exactly 2 weeks at the start of each development cycle. It opens immediately after the previous stable release is publicly cut kernel.org. During this phase, only maintainers with commit access to the kernel tree can merge code. All merged code must have first passed review in relevant subsystem mailing lists to address design and implementation concerns before inclusion.
6–8 Week Release Candidate (RC) Testing Phase
The second phase focuses on bug fixing and regression testing, with release candidate (RC) builds published for community validation before a final stable release is cut kernel.org. The RC phase lasts 6 to 8 weeks total, with 6 to 8 candidate builds released at weekly intervals kernel.org.
Each RC build is tagged with an -rc suffix, for example 6.13-rc1 and 6.13-rc2, to distinguish it from final stable releases kernel.org. Final mainline releases are only published when RC builds pass core functionality tests for common hardware and workloads. No outstanding critical regressions can be identified by the testing community for a release to be declared stable.
Short Post-Release Maintenance Window
Once a mainline version is declared stable, it enters a short maintenance phase. Point releases are published during this phase to address critical bugs and security vulnerabilities kernel.org. Standard stable non-LTS releases receive maintenance updates for approximately 8 to 10 weeks kernel.org. Support ends when the next even-numbered stable version is released. At that point, the older branch reaches end-of-life and no longer receives patches.
Decoding Linux Kernel Version Numbers
Version numbers encode release maturity at a glance, using a three-segment x.y.z format that has remained consistent since the kernel’s 1.0 release in 1994 kernel.org. Each segment conveys specific information about the release’s purpose.
Three-Segment x.y.z Format
The x segment denotes the major version, which increments only for significant architectural changes to the kernel. The y segment denotes the minor version, which increments for each regular release cycle. The z segment denotes point releases for bug fixes and patches, which increment sequentially without altering the release’s stability classification kernel.org.
Odd vs. Even Minor Version Stability Indicators
Odd minor (y) values indicate in-development mainline releases that are not intended for production use. Even minor values mark stable, production-ready releases that have completed full release candidate testing kernel.org. The minor version number is the most reliable indicator of release stability for operators planning deployments.
Even minor values confirm a release has passed the full RC testing process and is safe for production use. Odd minor values signal an in-progress development track that may break existing workloads or hardware compatibility. Operators should avoid deploying odd-numbered minor versions to production systems under any circumstances.
Point Release Function and Frequency
Point (z) releases are bug fix, security patch, and driver update releases for stable branches. They are published as needed between minor stable releases, and never add new features or alter the branch’s stability classification kernel.org.
For active stable branches, point releases are typically published 1 to 3 times per month kernel.org. They address regressions and security vulnerabilities identified after the initial stable launch. For example, version 6.12.1, released shortly after the initial 6.12 stable launch, includes fixes for regressions and security vulnerabilities identified during the 6.12 release candidate testing phase kernel.org.
The June 2026 launch of Eclipsa Video HDR for Android depends on these stable point releases to deliver new media processing capabilities and security patches to Android smartphones, which run on Linux kernel codebases Android Developers.
Long-Term Support (LTS) Tracks for Production Use
LTS releases are a subset of stable even-numbered versions that receive security and bug fixes for extended multi-year periods, far longer than the standard stable maintenance window of 8 to 10 weeks kernel.org. These extended support windows reduce the frequency of required kernel upgrades and associated testing overhead for long-lived infrastructure, from embedded devices to enterprise servers.
Active LTS Support Timelines as of 2026
LTS releases are selected based on demand from enterprise, embedded, and consumer stakeholders, and are announced at the start of their support window by the kernel maintainer team. As of 2026, the kernel project maintains 5 active LTS branches with published end-of-life dates kernel.org:
| LTS Version | Initial Release Year | End-of-Life Date | Total Support Duration |
|---|---|---|---|
| 5.10 | 2020 | December 2026 | ~6 years |
| 5.15 | 2021 | October 2027 | ~6 years |
| 6.1 | 2022 | December 2027 | ~5.5 years |
| 6.6 | 2023 | December 2028 | ~5 years |
| 6.12 | 2024 | December 2029 | ~5 years |
For context, the 5.10 LTS release launched in December 2020. It received updates for over 5 years before reaching end-of-life in December 2026, per the kernel project’s support policy kernel.org. The older 4.19 LTS release received support for 6 years for enterprise and embedded use cases with long maintenance requirements kernel.org.
Production Use Cases for LTS Kernels
These extended support timelines make LTS releases the default choice for production deployments that cannot tolerate frequent maintenance windows. For example, Samsung’s new education tools for interactive displays announced at ISTELive 26 run on embedded Linux kernels. These kernels benefit from multi-year LTS support to minimize downtime in K-12 classroom settings, where extended outages disrupt instructional time Samsung News.
Similarly, Samsung’s Art Store runs on smart displays powered by Linux kernel 5.15 LTS. The extended support window delivers consistent performance and security updates to end users without requiring frequent device reboots Samsung News.
Frequently Asked Questions About Linux Kernel Releases
- 1.Should I deploy a mainline kernel version to production?No. Mainline kernel versions with odd minor version numbers, for example 6.13 or 6.15, are in-development releases that have not completed full release candidate testing kernel.org.
They may contain untested features, regressions, or hardware compatibility issues that can disrupt production workloads.
Only even-numbered stable or LTS releases are approved for production use.
- 2.How long do standard stable kernel releases receive updates?Standard stable non-LTS releases receive maintenance updates for approximately 8 to 10 weeks after their initial launch kernel.org.
Support ends when the next even-numbered stable version is released.
At that point, the older stable branch reaches end-of-life and no longer receives security or bug fix patches.
- 3.How can I check if a kernel version is LTS?The kernel project publishes an official list of active LTS releases and their support timelines on kernel.org.
The list is updated each time a new LTS release is designated or an existing one reaches end-of-life kernel.org. As of 2026, active LTS releases include 5.10, 5.15, 6.1, 6.6, and 6.12.
Their support windows extend 2 to 4 years from their initial launch.
- 4.What is the difference between a point release and a minor release?A point release, the z segment in x.y.z versioning, is a bug fix, security patch, or driver update for an existing stable branch.
It does not add new features or alter the branch's stability classification kernel.org. A minor release, the y segment, is a new stable or mainline version that may include new features, and increments the version's minor number. For example, 6.12.1 is a point release for the 6.12 stable branch.
6.12 is the initial minor stable release, and 6.13 is the next in-development mainline minor release. Bottom line: For production workloads, select an active even-numbered stable or LTS kernel release rather than odd-numbered mainline development versions. Prioritize LTS branches like 6.6 (supported until December 2028) for long-lived infrastructure to minimize upgrade overhead.
Validate new features against release candidate builds during the 2-week merge window and 6-8 week RC testing phase to align upgrades with your organization's maintenance schedule and avoid compatibility issues in deployment.
