Section 1.5. Kernel Release Information

1.5. Kernel Release Information

As with any software project, understanding the project's versioning scheme is a key element in your involvement as a contributor. Prior to Linux kernel 2.6, the development community followed a fairly simple release and development tree methodology. The even-number releases (2.2, 2.4, and 2.6) were considered stable branches. The only code that was accepted into stable branches was code that would fix existing errors. Development would continue in the development tree that was marked by odd numbers (2.1, 2.3, and 2.5). Eventually, the development tree would be deemed complete enough to take most of it and release a new stable tree.

In mid 2004, a change occurred with the standard release cycle: Code that might normally go into a development tree is being included in the stable 2.6 tree. Specifically, "…the mainline kernel will be the fastest and most feature-rich kernel around, but not, necessarily, the most stable. Final stabilization is to be done by distributors (as happens now, really), but the distributors are expected to merge their patches quickly" [Jonathan Corbet via http://kerneltrap.org/node/view/3513].

As this is a relatively new development, only time will tell whether the release cycle will be changed significantly in the long run.