About Kernel Versioning

Command to show the running kernel version:

[root@wordsworth modules]# uname -r
2.6.9-42.0.3.ELsmp

Kernel Version Numbers:

The Linux kernel version numbers consist of three numbers separated by decimals, such as 2.2.14. The first number is the major version number. The second number is the minor revision number. The third number is the patch level version.

At any given time there is a group of kernels that are considered “stable releases” and another group that is considered “development.” If the second number of a kernel is even, then that kernel is a stable release. For example, the 2.2.14 kernel is a stable release because the second number is even. If the second number is odd, then that kernel is a development release. For example, the 2.3.51 is a development release because the second nubmer is odd.

Once the 2.3.x branch is considered finished, then it will become the 2.4.0 kernel. Patches will then appear for the 2.4.x branch and development work will begin on the 2.5.x branch. If the 2.3.x advancements are significant enough to be considered a major revision, the 2.3.x branch will become 3.0.0 and development work will begin on the 3.1.x branch.

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