[Bug 1911614] Re: Ubuntu 20.04 and 20.04.1 images use linux-generic-hwe-20.04 instead of linux-generic

[Erick Brunzell]

Documentation is horribly insufficient in this regard. To quote the link
given, "Ubuntu Desktop flavour now always tracks HWE kernel (hardware
enablement). It means that from 20.04.2 release Ubuntu Desktop will gain
new major kernel versions every 6 months through to summer of 2022".

The words "from 20.04.2 release Ubuntu Desktop will gain new major
kernel versions every 6 months" speak volumes, sadly incorrect volumes.
20.04.2 is not even due for release until next month but we've been
getting HWE kernel updates for a couple of weeks already!

All of the following documentation needs serious updating and must
include methods to remain on the GA kernel if one wishes:

The first, also from the release notes, states clearly "Ubuntu 20.04 LTS
is based on the long-term supported Linux release series 5.4":

https://wiki.ubuntu.com/FocalFossa/ReleaseNotes#Updated_Packages

None of these have been updated to adequately reflect the change to opt-
out of HWE rather than opt-in if using original (20.04) or first point
release (20.04.1) installation media as had always been the case
previously.

https://wiki.ubuntu.com/Kernel/LTSEnablementStack
https://wiki.ubuntu.com/Kernel/RollingLTSEnablementStack
https://ubuntu.com/kernel/lifecycle

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https://bugs.launchpad.net/bugs/1911614

Title:
  Ubuntu 20.04 and 20.04.1 images use linux-generic-hwe-20.04 instead of
  linux-generic

Status in ubuntu-meta package in Ubuntu:
  Confirmed

Bug description:
  Beginning about January 8th Focal users that installed Focal using
  either the Ubuntu 20.04 or 20.04.1 installation media began getting
  updated to the 5.8 series linux kernel. Those who had installed using
  the Ubuntu Focal Beta were not effected. This is because Focal Beta
  was properly built with ‘linux-generic’ but the 20.04 and 20.04.1
  images were built with ‘linux-generic-hwe-20.04‘. This can be easily
  verified by looking at the iso manifest:

  https://releases.ubuntu.com/20.04.1/ubuntu-20.04.1-desktop-
  amd64.manifest

  Note: old-release manifests (where 20.04 Beta and 20.04 reside) must
  be downloaded here:

  https://old-releases.ubuntu.com/releases/20.04/

  The expected behavior is for Ubuntu Focal users to remain on the 5.4
  series kernel unless they install with 20.04.2 or later images as
  indicated here:

  https://wiki.ubuntu.com/Kernel/LTSEnablementStack

  While not entirely updated it says “if one wants to remain on the
  original GA (General Availability) stacks, the options [include];
  Install from a previous
  12.04.0/12.04.1/14.04.0/14.04.1/16.04.0/16.04.1/18.04.0/18.04.1 point
  release and update”.

  Jump just below that to the Focal specific notes and it says “The
  20.04.2 and newer point releases will ship with an updated kernel and
  X stack by default for the desktop”. Since 20.04.2 is not even due for
  release until next month it makes no sense for updates to the 5.8
  series kernel to be occurring unless the focal-proposed repos are
  enabled even if HWE protocols had been changed.

  It’s also worth noting that thankfully no accompanying HWE X stack is
  yet available in the repos. I say thankfully because my efforts at
  downgrading the X stack in 16.04 and 18.04 were never successful! But
  the lack of a matching X stack may explain the many complaints on the
  forums about broken graphics???

  It’s also worth noting that even the release notes say that “Ubuntu
  20.04 LTS is based on the long-term supported Linux release series
  5.4“.

  https://wiki.ubuntu.com/FocalFossa/ReleaseNotes#Linux_Kernel

  Scroll to the bottom here and you’ll also see that 20.04 and 20.04.1
  are supposed to be supported with the 5.4 series kernel for the entire
  5 year life span:

  https://ubuntu.com/kernel/lifecycle

  The other flavors’ 20.04 and 20.04.1 images were all built correctly
  with ‘linux-generic’ with the possible exception of Ubuntu Studio
  which uses a kernel stack I’m not familiar with. I’m also uncertain
  about Ubuntu server because I’m simply not familiar with it.

  Original bug description below:

  ##################################################################

  Just as the title says, the 20.04 and 20.04.1 images use the HWE
  version of linux-generic resulting in upgrades to the 5.8 series
  kernel. This seems to effect Ubuntu only, or I should say I checked
  the Kubuntu, Ubuntu Mate, Xubuntu, and Lubuntu iso manifests which all
  correctly list linux-generic. Also HWE is not truly complete without
  the accompanying HWE Xstack.

  I checked all the documentation I could find and this was clearly not
  intentional. In fact the manifest for Ubuntu Focal Beta still used
  linux-generic, so this got messed up some time between April 3, 2020
  and April 23, 2020. Here's just one example of the documentation for
  kernel support in Focal LTS:

  https://ubuntu.com/about/release-cycle#ubuntu-kernel-release-cycle

  Installations performed with 20.04 and 20.04.1 media were supposed to
  remain on the 5.4 series kernel throughout Focal's 5 year lifespan as
  had been the case since HWE was introduced. The first step in fixing
  this needs to be stopping fresh installs of Focal using the 20.04 and
  20.04.1 media from immediately upgrading to the 5.8 series kernel.

  It might be a little tricky to revert users from 5.8 to 5.4, but there
  have been reports of breakage, particularly concerning Broadcom wifi
  drivers and some graphics problems. But the graphics problems could
  also be exacerbated by the lack of the matching HWE Xstack? At any
  rate it's a bug.

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