Ubuntu – How to opt in to Early Preview of LTS enablement stack

hardware-enablement-stackkernelltsxorg

As explained in the wiki article LTS Enablement Stacks,

The Ubuntu LTS enablement stacks provide newer kernel and X support for existing LTS releases. These can be installed manually, or are automatically shipped if installing from 12.04.2/14.04.2 and newer release media.

As shown in the chart below, newer hardware enablement stacks become available as 'early preview' (EP) a few months before the next point release.

Ubuntu Kernel Support Schedule

The note in the chart says

Early preview of the HWE kernel being introduced in the point release will be available in the -updates pocket.

What is the '-updates pocket' and how do I opt in to it and to EP of LTS Enablement Stack?

If this operation is reversible, how do I opt back out?

Here's the details of my current situation, but I would really prefer this to be a broader question, applicable at least to all versions of 12.04 and 14.04.

I'm running a 14.04 LTS, installed and updated from 14.04.0 netinstall (Ubuntu 14.04.2, kernel 3.13) and I'm interested in trying out an Ubuntu 15.04 (vivid) and later kernels as they become available in Early Preview; especially an Ubuntu 16.04 kernel – because the support for older updated LTS enablement stacks ends the moment the new one becomes available, I figure it's good to try newer stacks in EP mode.

Best Answer

Generally speaking it is done by installing packages like -lts-, e.g. linux-generic-lts-utopic for Ubuntu 14.04.

With kernels it is quite easy. But with graphical stack it is not that straight forwared because of dependencies, especially on 64-bit systems. Commands given in that article are not quite correct in many cases and can remove a lot from you system.

It is reversable. But it is better if you specify which version do you run and which kernel/graphics you want to upgrade. Then it will be possible to give you a more specific guide.

-Updates pocket is a part of Ubuntu repositories. You do not need to do anything to install from there, becuse this part is enabled by default.

For Ubuntu 14.04 kernel from Ubuntu 14.10 is available (3.16). It can be installed by running

sudo apt-get install linux-generic-lts-utopic

Very soon kernel from 15.04 (3.19) will be available. It is in proposed repository, and will get to main sime time next week, I guess. It can be installed by

sudo apt-get install linux-generic-lts-vivid