[Bug 508901] Re: update-grub sets wrong root argument

[Peter Passchier]

This is fixed by applying this:
https://gist.github.com/pepa65/85d5fcd1e12bc6028501c746258ac8cf

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Title:
  update-grub sets wrong root argument

Status in grub2 package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: grub2

  I've made a backup of my system with dd and then changed the UUID and
  label of the drive.  I would like to be able to boot from either the
  main system or the backup, ideally regardless of whether the backup is
  in a USB enclosure or mounted internally.

  When I run update-grub, even though it correctly finds the backup and
  uses its UUID as a parameter for the search command, it still sets the
  root= argument of the linux command to the main system.  This makes
  the backup unusable.

  So in my setup, the original drive is
  7f0e857e-6118-4696-bdc6-7c51b31e1002, and the backup is 9de2fc84-1128
  -41eb-9c1b-a444d070d415.  Each one has its fstab set up to mount
  itself as root.  The generated boot options look like this:

  ### BEGIN /etc/grub.d/10_linux ###
  menuentry "Ubuntu, Linux 2.6.31-17-generic" {
          recordfail=1
          if [ -n ${have_grubenv} ]; then save_env recordfail; fi
  	set quiet=1
  	insmod ext2
  	set root=(hd0,1)
  	search --no-floppy --fs-uuid --set 7f0e857e-6118-4696-bdc6-7c51b31e1002
  	linux	/boot/vmlinuz-2.6.31-17-generic root=/dev/sda1 ro   quiet splash
  	initrd	/boot/initrd.img-2.6.31-17-generic
  }
  ...
  ### BEGIN /etc/grub.d/30_os-prober ###
  menuentry "Ubuntu, Linux 2.6.31-17-generic (on /dev/sdb1)" {
  	insmod ext2
  	set root=(hd1,1)
  	search --no-floppy --fs-uuid --set 9de2fc84-1128-41eb-9c1b-a444d070d415
  	linux /boot/vmlinuz-2.6.31-17-generic root=UUID=7f0e857e-6118-4696-bdc6-7c51b31e1002 ro quiet splash
  	initrd /boot/initrd.img-2.6.31-17-generic
  }

  I tried uncommenting the GRUB_DISABLE_LINUX_UUID=true" line in
  /etc/default/grub, but it only affects the output of 10_linux, not
  30_os-prober.

  ProblemType: Bug
  Architecture: i386
  Date: Sun Jan 17 21:07:18 2010
  DistroRelease: Ubuntu 9.10
  Package: grub2 1.97~beta4-1ubuntu4.1
  ProcEnviron:
   LANGUAGE=en_GB.UTF-8
   PATH=(custom, user)
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  ProcVersionSignature: Ubuntu 2.6.31-17.54-generic
  SourcePackage: grub2
  Uname: Linux 2.6.31-17-generic i686

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