[Bug 978464] Re: After LTS->LTS (lucid2precise) upgrade, upon reboot drops into grub recovery shell

[Steve Langasek]

On Tue, May 15, 2012 at 06:59:35PM -0000, Phillip Susi wrote:
> That's not really a fix Dmitrijs.

It's the fix I asked him to implement.  As explained in the earlier
comments, there is no way we can guarantee with 100% reliability that the
MBR will be upgraded when the package is upgraded.  We should therefore
maintain maximum compatibility here with old versions of grub - there's no
reason not to.

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https://bugs.launchpad.net/bugs/978464

Title:
  After LTS->LTS (lucid2precise) upgrade, upon reboot drops into grub
  recovery shell

Status in “grub2” package in Ubuntu:
  Fix Released
Status in “grub2” source package in Precise:
  Triaged
Status in “grub2” source package in Quantal:
  Fix Released

Bug description:
  [Impact]
  Any system upgraded from Lucid->Precise is affected, if and only if the user does not opt-in to reinstall grub-pc bootloader during the do-release-upgrade/dist-upgrade nor reinstalls grub-pc into MBR manually before mandatory reboot.

  The affected system will fail to reboot, and will drop into grub shell
  requiring manual boot.

  [Workaround]
  Users should follow the warnings about potential incompatibilities, and reinstall grub-pc into MBR/partitions as appropriate. This will update their grub to a supported version. If users still preffers to keep old grub, we provide Development and Stable Fixes.

  [Development Fix]
  In the Development branch, the fix was to use backwards compatible syntax in grub.cfg. Specifically, using ${var} syntax for variable substitution. (NB! the $var syntax was introduced as fully supported after the grub2 1.98 release, that is after lucid)

  [Stable Fix]
  Patch can be found at: https://code.launchpad.net/~dmitrij.ledkov/ubuntu/precise/grub2/fix-978464/+merge/105844

  [Test Case]
  1) Install/Have already installed: grub-common grub-pc grub-pc-bin grub2-common from lucid (1.98-1ubuntu5)
  2) Make sure version of 1.98-1ubuntu5 of grub2 is used as bootloader, e.g. run  `sudo grub-install /dev/sdX  # Example: sudo grub-install /dev/sda'

  Note: step 1 & 2 can be accomplished by doing a fresh lucid install in
  environment which uses grub-pc, e.g. desktop or server images, but not
  ec2 "cloud" images.

  3) Upgrade grub-common grub-pc grub-pc-bin grub2-common from precise-proposed (1.99-21ubuntu3.1) but do not reinstall grub into MBR. (as part of do-release-upgrade/dist-upgrade select "Yes, continue without reinstalling grub")
  4) Reboot

  Assert True: reboot succeeds.

  To test that bug exists: install grub-common grub-pc grub-pc-bin
  grub2-common from precise (1.99-21ubuntu3) but dot reinstall grub into
  MBR. Rebooting should drop into grub recovery console.

  [Regression Potential]
  Regressions are not anticipated, since only variant of valid syntax is changed. Nonetheless users should see https://help.ubuntu.com/community/Grub2 if they are having troubles booting their system.

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