[Bug 554307] Re: linux-boot-prober yields wrong uuid for kernel root parameter

[Rüdiger Kupper]

I agree with you that os-prober cannot automatically tell, which kernel
files belong to which installation, if several linux installs share the
same /boot.

(1) Still, its behaviour could be easily improved: If os-prober detects
two linux installs with a shared /boot, it could simply ask the user,
which install should boot which kernel. Instead it silently fails with
no warning and the user ends up with a grub.cfg that fails booting one
of the installs.

(2) The resulting grub.cfg is definitely inconsistent, even if os-prober cannot decide which kernel belongs to which install. To illustrate this, kindly have a look at my original bug report (which I have later marked a duplicate of this): Bug #554307
In the description of Bug #554307 you see the grub.cfg the user gets when running update-grub on two installs sharing /boot. Yes, os-prober cannot determine which install should boot which kernel. But this is not the problem I report there. The resulting grub.cfg looks like this:

[...]
menuentry '<name of first linux OS> (on /dev/sda2)' [...] {
        [...]
        set root='(hd0,msdos1)' # <- this is the boot partition, /dev/sda1
        search --no-floppy --fs-uuid --set=root <UUID of /dev/sda1>
        linux /vmlinuz-x.x.x root=UUID=<UUID of /dev/sda2> [...]
        initrd [....]
}
menuentry '<name of second linux OS> (on /dev/sda3)' [...] {
        [...]
        set root='(hd0,msdos1)' # <- this is the boot partition, /dev/sda1
        search --no-floppy --fs-uuid --set=root <UUID-of-/dev/sda1>
        linux /vmlinuz-y.y.y root=UUID=<UUID of /dev/sda2 (!!!)> [...]
        initrd [....]
}
[...]

Look at the *second* menuentry: Its *name* correctly refers to the
*second* install (on /dev/sda3). Still its *linux call* refers to the
*first* install an /dev/sda2. This is clearly inconsistent and a bug.

My original report in #554307 was about this bug. If you feel that this
differs from the issues reported here, I will be unlisting this bug as a
duplicate and reopen it.

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https://bugs.launchpad.net/bugs/554307

Title:
  linux-boot-prober yields wrong uuid for kernel root parameter

Status in os-prober package in Ubuntu:
  Won't Fix

Bug description:
  Binary package hint: os-prober

  My Partitions:
  sda5 swap
  sda6 lucid
  sda7 karmic

  linux-boot-prober doesn't take the root partition as kernel root
  paraameter for my karmic installation.

  matthias at netbook:/boot/grub$ ls -l /dev/disk/by-uuid/
  insgesamt 0
  lrwxrwxrwx 1 root root 10 2010-04-02 23:08 199233d9-7174-445d-81df-eb9c95af871f -> ../../sda7
  lrwxrwxrwx 1 root root 10 2010-04-02 23:08 1E4F-1E00 -> ../../sda2
  lrwxrwxrwx 1 root root 10 2010-04-02 23:08 523cd06e-f460-4c88-b1e9-5382df4e5d37 -> ../../sda6
  lrwxrwxrwx 1 root root 10 2010-04-02 23:08 82A8C040A8C03507 -> ../../sda1
  lrwxrwxrwx 1 root root 10 2010-04-02 23:08 837c2ad3-a209-4668-b864-a79320c5094b -> ../../sda5

  matthias at netbook:/boot/grub$ linux-boot-prober /dev/disk/by-uuid/199233d9-7174-445d-81df-eb9c95af871f
  unshare failed: Operation not permitted
  /dev/disk/by-uuid/199233d9-7174-445d-81df-eb9c95af871f:/dev/disk/by-uuid/199233d9-7174-445d-81df-eb9c95af871f:Ubuntu, Linux 2.6.31-16-generic:/boot/vmlinuz-2.6.31-16-generic:/boot/initrd.img-2.6.31-16-generic:root=UUID=523cd06e-f460-4c88-b1e9-5382df4e5d37 ro quiet splash
  ...

  I suspect that when I try to boot my karmic, it boots the karmic
  kernel with lucid userland -> nothing works.

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: os-prober 1.36
  ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
  Uname: Linux 2.6.32-19-generic i686
  Architecture: i386
  Date: Sat Apr  3 01:15:03 2010
  ProcEnviron:
   LANG=de_DE.UTF-8
   SHELL=/bin/bash
  SourcePackage: os-prober

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