[SRU] grub can no longer detect kernels after ubuntustudio-lowlatency-settings is uninstalled

[Erich Eickmeyer]

[Impact]

 * When ubuntustudio-lowlatency-settings is installed, it disables the executable
   bit on /etc/grub.d/10_linux because it installs a replacement file at
   /etc/grub.d/09_lowlatency in order to ensure that the lowlatency kernel is
   always default when both generic and lowlatency are installed.

 * ubuntustudio-lowlatency-settings does not contain a postrm script to reenable
   executability (+x) of /etc/grub.d/10_linux after it has been removed, thus
   rendering grub unable to detect any installed kernels, potentialy breaking
   installations and causing people's systems unable to boot.

[Test Case]

 * Install Ubuntu Studio or add ubuntustudio-lowlatency-settings to any
   installation

 * Uninstall ubuntustudio-lowalatency-settings, run update-grub.

 * Reboot. Kernels will be unavailable for boot. This is further proven prior to
   this when update-grub is run as it will not detect any installed kernels.

[Regression Potential]

 * The only regression this may have is that the .postrm script does not actually
   add +x, but this is highly unlikely as it adds it if the /etc/grub.d/10_linux
   file simply exists, even if the executable bit is already set.

[Other Information]

 * This was recently discovered when I installed the surface-linux kernel on my
   MS Surface Pro 4 and found it unable to boot the custom kernel, as with
   ubuntustudio-lowlatency-settings it was only recognizing the generic and
   lowlatency kernels. Removing ubuntustudio-lowlatency-settings and attempting
   to run update-grub resulted in no kernels detected. Upon investigation,
   I discovered that the +x bit was not set in /etc/grub.d/10_linux.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntustudio-default-settings - 20.10.37

---------------
ubuntustudio-default-settings (20.10.37) groovy; urgency=medium

  * add postrm script for ubuntustudio-lowlatency-settings (LP: #1892949)

 -- Erich Eickmeyer <email address hidden> Tue, 25 Aug 2020 18:07:02 -0700

[Chris Halse Rogers (raof)]

An upload of ubuntustudio-default-settings to focal-proposed has been rejected from the upload queue for the following reason: "Please re-upload with a changelog entry that describes to the user what the update is going to fix.".

[Erich Eickmeyer (eeickmeyer)]

There is a new upload of this package awaiting approval.

[Łukasz Zemczak (sil2100)]

Hello Erich, or anyone else affected,

Accepted ubuntustudio-default-settings into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/ubuntustudio-default-settings/20.04.2.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Brian Murray (brian-murray)]

The fix for this bug has been awaiting testing feedback in the -proposed repository for focal for more than 90 days. Please test this fix and update the bug appropriately with the results. In the event that the fix for this bug is still not verified 15 days from now, the package will be removed from the -proposed repository.

[Łukasz Zemczak (sil2100)]

Any luck in verifying this? It seems important enough to get it in, if possible.

[Ross Gammon (rosco2)]

I think I may have a spare machine that I can play with after I finish setting up a new one later today.
I could do the test on this machine, but I really need it operational!
Hopefully I will report back in the next day or so.

[Erich Eickmeyer (eeickmeyer)]

Actually, I totally spaced this. I did verify it's working fine in Focal using the fix. I just forgot to mark verification done.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntustudio-default-settings - 20.04.2.2

---------------
ubuntustudio-default-settings (20.04.2.2) focal; urgency=medium

  * Ensure removing ubuntustudio-lowlatency-settings package
    doesn't remove all kernels from GRUB boot menu (LP: #1892949)

 -- Erich Eickmeyer <email address hidden> Tue, 25 Aug 2020 18:12:28 -0700

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for ubuntustudio-default-settings has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.