Kernel versioning

Versioning

OpenVZ kernel versions are named like 2.6.n-XXXtestYYY.z and 2.6.n-XXXstabYYY.z.

2.6.n is a vanilla kernel version (i.e. the one from kernel.org) which this OpenVZ kernel is based on.
XXX is a major OpenVZ kernel version number, which usually changes from release to release, or when dramatic changes to the kernel are made.
test series kernels are unstable kernel releases, which are usually under extensive development, while stab series kernels are more or less stable kernel releases which are close to be released or are in production already.
YYY is a minor OpenVZ kernel version number, which changes from build to build, when bugfixes or small feature changes were made.
z is an add-on number; it is used as rpm's Release field and in most cases is set to 1.

Usual kernel development cycle looks like this:

021test000 → 021test001 → ... → 021test012 → here kernel is declared stable → 021stab000 → 021stab001 → ... → 021stab023

A few kernel branches may be developed in parallel. For example, as of 13th of June, 2006, there are four branches:

stable, based on 2.6.8, currently at 2.6.8-022stab077.1
development, based on 2.6.16, currently at 2.6.16 026test014.4
FC5, based on latest Fedora Core 5 kernel, currently at 2.6.16-1.2111_FC5.026test012
SUSE10, based on latest SUSE10 kernel, currently at 2.6.16.13_4_ve026test012-2