Kernel Versions | SUSE Linux 10.0 Unleashed

In the preceding section, I mentioned the kernel-of-the-day repository. The very existence of this place gives you a sense of the pace of development of the kernel. As new features are added, bugs are fixed, and new technology is incorporated into the code base; new iterations of the kernel are coming out all the time.

This is the reason why kernel version numbers are so complicated. With most applications, versioning is a relatively simple operation, with a major version number indicating lots of new features (or, in the case of commercial applications, at least enough to justify paying for an upgrade), and one or two digits after the dot indicating bug fix updates.

For example, SUSE Linux Professional 9.2 shipped with kernel version 2.6.8-24.10. You can break this down into these sections:

Major version Currently at 2.
Minor version Currently at 6. Even-numbered minor versions are stable kernels; development releases are odd numbered.
Sublevel number This is the current iteration of the kernel. If you visit www.kernel.org, you'll see it listed as the stable version. This number changes much more often than the first two. In this case, it's 8.
Patch level When there is a dash after the sublevel, the next number represents the number of times small patches have been added by members of the kernel team. Here, it's 24.
Extraversion level This number represents the work the SUSE engineers have done with the latest patch. Here, it's 10. Generally, this work addresses code issues in the "stock" kernel and additional hardware support.

To see what kernel version you're running, type uname -r at the shell prompt.

Note

Alan Cox has taken on many responsibilities within the kernel hacking team. One of those tasks (though considerably less official) is releasing periodic "ac" patches distinguished by the -ac marker at the end of the kernel version. Stored and downloadable at http://www.kernel.org/pub/linux/kernel/people/alan/, these patches include hints at what's being cooked up by the team working on the test kernel. Experimenters can join in the testing.