Infrastructure Software

Hello,

Wikipedia at http://en.wikipedia.org/wiki/Linux_kernel#Maintenance outlines, that 2.6.39 is the last stable release of the 2.6 kernel series. From what I understand, this does not apply to the Oracle UEK kernel, which still uses the 2.6.39 notation for compatibility reasons.

Reading the OL 6.4 release notes at https://oss.oracle.com/ol6/docs/RELEASE-NOTES-U4-en.html#ol_uek2_64rn the UEK2 Release 2 kernel 2.6.39-400 is based on the upstream kernel 3.0.36. The UEK2 R1 kernel was based on the mainline 3.0.16 kernel. Does upstream and mainline kernel mean the same? I read that each mainline build is named by the base upstream version. What does that mean?

The link https://www.kernel.org shows an interesting view, listing various kernels, including a 3.9 mainline kernel. So it seems there is a lot of parallel development going on with versions 2.6, 3.0 and 3.2 and later. Searching around, I found the Oracle Linux playground repository https://blogs.oracle.com/wim/entry/oracle_linux_playground_channel_sample which already provides kernel 3.8.

Why are there so many different kernel versions? Why is the Oracle UEK kernel based on 3.0 and not 3.5, for instance? Will the next release of the UEK kernel be based on the 3.9, which is a mainline kernel?

Thanks.