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I only recently became aware that LTS wasn't just an Ubuntu thing - there's LTS kernel versions too. Yet the kernel version used (3.13) in Ubuntu 14.04 LTS is not an LTS kernel version. Is it considered unimportant whether or not a kernel version is LTS?

Sam
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A short answer is: "It is an LTS kernel".

Mainline kernel developers didn't make it an LTS, but the Canonical Kernel Team did.

The 3.13 kernel is maintained as an LTS according to the mainline rules as 3.13-ckt. Security and small hardware support patches are backported the same way as in mainline LTS kernels.

You can find the source here: http://kernel.ubuntu.com/git/ubuntu/linux.git

Based on this kernel the Ubuntu debianized kernels are made.

The 3.13 Ubuntu kernel source is here: http://kernel.ubuntu.com/git/ubuntu/ubuntu-trusty.git

The main idea is that the Canonical Kernel Team extends support of mainline kernels when they are used in LTS Ubuntu releases.

When I send a kernel patch that is supposed to be backported to stable kernels, I add Cc: stable@vger.kernel.org to the commit message.

First it gets to the latest mainline kernels, then is backported to mainline LTS kernels and ckt kernels the same way.

Pilot6
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    Thanks for explaining, Pilot6. Seems strange that they wouldn't simply choose an LTS kernel and save themselves the added work but looking at 12.04 and 16.04, it seems 14.04 was a one-off exception. – Sam Jul 07 '17 at 09:31
  • The reason for that is to get a newer kernel for a new LTS release. They try to use LTS kernels when it is possible. – Pilot6 Jul 07 '17 at 09:32
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    @Sam As you can see not only 3.13 is extended, but 3.19 and 4.2. – Pilot6 Jul 07 '17 at 09:36
  • What actually got me thinking about this was installing Mint 18.2 (16.04.2-based) and getting kernel 4.8 (non-LTS) when 4.9 LTS had already been out for a while? – Sam Jul 07 '17 at 09:43
  • The 4.8 came from 16.10 as HWE. It was the latest at that time. If you know how it works, it is straight forward. 16.04.2 is not a new release. – Pilot6 Jul 07 '17 at 09:45