[Bug 788298] Re: grub-reboot changes boot default permanently on Lucid LTS

[dann frazier]

Verification:

On a system w/ /boot on an md device:

dannf at mdraid:~$ sudo grub-reboot 0
[sudo] password for dannf: 

WARNING: Detected GRUB environment block on diskfilter device
0 will remain the default boot entry until manually cleared with:
    grub-editenv /boot/grub/grubenv unset next_entry


On a system w/ /boot on a /dev/vda:
ubuntu at ubuntu:~$ sudo grub-reboot 2
ubuntu at ubuntu:~$ 

And it worked as expected.


** Tags removed: verification-needed verification-needed-bionic
** Tags added: verification-done verification-done-bionic

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https://bugs.launchpad.net/bugs/788298

Title:
  grub-reboot changes boot default permanently on Lucid LTS

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2-signed package in Ubuntu:
  Fix Released
Status in grub2 source package in Bionic:
  Fix Committed
Status in grub2-signed source package in Bionic:
  Fix Committed

Bug description:
  [Impact]
  The grub-reboot manpage says it will "Set the default boot menu entry for GRUB, for the next boot only." But, that's a promise it cannot keep when GRUB cannot write to the environment block, such as when it is stored on Linux software RAID (md) or LVM devices. An administrator of such a system may expect grub-reboot to work as documented, only to find that their change is now permanent, requiring manual recovery. Users without console access may rely on grub-reboot to provide a mechanism for testing a possible-broken boot entry. If that entry causes the system to fail to boot, they may find their system unrecoverable.

  [Test Case]
  Run grub-reboot on an impacted system and check for a warning and instructions on manually restoring the default. Also, check for a warning in the grub-reboot manpage.

  [Regression Risk]
  This is a documentation change only. The documentation is emitted by (trivial) code, so a bug in that code could lead to unintentional functional changes.

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