[Bug 1261817] Re: Grub2 does not setup existing linux operating systems correctly on PowerPC

[Adam Smith]

Attached is the patch.  If anybody wants to fix this on their system
then all you need to do is edit the file /usr/lib/linux-boot-
probes/mounted/40yaboot and apply the changes.

** Attachment added: "Fix root UUID on PowerPC"
   https://bugs.launchpad.net/ubuntu/+source/os-prober/+bug/1261817/+attachment/3931882/+files/os-prober-patch

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https://bugs.launchpad.net/bugs/1261817

Title:
  Grub2 does not setup existing linux operating systems correctly on
  PowerPC

Status in “os-prober” package in Ubuntu:
  New

Bug description:
  Hello

  I don't know if Ubuntu have any plans to use Grub2 for PowerPC, but
  currently there is an easily fixable bug with os-prober:

  Existing installations that use yaboot will normally have their root
  defined like so in a yaboot.conf:

  root=UUID=big-long-number-0000

  However, os-prober (or more accuratly the file 40yaboot) when it scans
  the yaboot.conf will read this as

  root=UUID

  Consequently, when the operating system is selected from a grub2 menu
  it fails to boot.

  This can be solved by changing (in 40yaboot)

  		case "$1" in
  			root)
  				rootdev="$(dequote "$2")"

  to

  		case "$1" in
  			root)
  				shift 1
  				rootdev="$(dequote "${line#root=}")"

  I'll make a proper diff patch when I'm back on a linux machine.  I'm
  not sure if the shift 1 is necessary. but  some of the other cases
  seem to have it so I put it in.

  I had a look at yaboot-installer to see how that does things and
  interestingly that has its own piece of code to setup root:

  # Get UUID= or LABEL= for the given unix partition block device.
  # If it could not be determined, give the unix partition block device back.
  uuidlabel() {
    echo `devsymlink "$1" nobyid` \
    | sed -e "s,/dev/disk/by-uuid/,UUID=," \
          -e "s,/dev/disk/by-label/,LABEL=,"
  }

  root="`uuidlabel "$mappedpartition"`"

  This therefore doesn't suffer from this bug.  It's actually quite a
  sensible thing to do since root=/dev/sdx (which a lot of old installs
  used to use) is unreliable.  I don't know whether to create a patch
  for os-prober to do the same, or if the grub2 scripts should really
  sort it out.

  Anyway, that's turned into a bit of a ramble.  Oh, nearly forgot,
  fedora also has a patch on os-prober for PowerPC - see
  https://bugzilla.redhat.com/show_bug.cgi?id=825041 .

  I'm toying with the idea of creating an updated iso for Ubuntu 12.04.
  If I do then I plan to use Grub2 as the bootloader.  If you would like
  to collaborate on shifting PowerPC to grub2 then get in touch!

  Thanks

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