Kernel Development Process
The Kernel Development Process is a meticulous, structured methodology employed by developers and maintainers to ensure the stability, security, and efficiency of the Linux kernel. Here's an in-depth look:
Overview
The process involves several stages from initial code submission to integration into the mainline kernel:
- Submission: Developers submit patches or series of patches to the relevant subsystem maintainers or to the Linux Kernel Mailing List (LKML).
- Review: These patches are reviewed by maintainers, other developers, and sometimes the community for quality, correctness, and relevance.
- Testing: Patches are tested through automated systems like Linux Testing Project, as well as through community-driven testing efforts.
- Merging: Once a patch or series of patches passes the review and testing, it is merged into the mainline kernel by the maintainers or by Linus Torvalds himself.
Key Aspects
- Maintainer Hierarchy: The Linux kernel has a hierarchical structure of maintainers. Subsystem maintainers handle specific areas like drivers, networking, or filesystems, while Linus Torvalds oversees the entire kernel.
- Git and Patch Submission: The kernel development uses Git for version control. Patches are typically submitted using Git's email functionality, allowing for review before being merged.
- Stable Release Cycle: After the merge window, where new features are added, the kernel goes through a stabilization phase where only bug fixes are accepted until the next release.
- Documentation: All patches must include comprehensive documentation explaining the changes, rationale, and any potential impacts on other subsystems or users.
History and Evolution
The Kernel Development Process has evolved significantly since the first release of Linux in 1991:
- Originally, Linus Torvalds was the sole maintainer, but as the project grew, a more distributed model was adopted.
- The introduction of Git in 2005 by Linus Torvalds revolutionized the development process by making branching and merging easier.
- The establishment of the Linux Foundation in 2007 helped formalize governance, including the development process.
Context
Understanding the kernel development process is crucial for:
- Contributors to ensure their changes are reviewed and accepted into the kernel.
- Users to understand how features and fixes are incorporated into the kernel they run.
- Companies that depend on Linux to understand the lifecycle of kernel updates and stability.
Sources
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