Grub2 does not setup existing linux operating systems correctly on PowerPC

[Adam Smith]

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

[Adam Smith (adamsmith)]

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.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "Fix root UUID on PowerPC" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[Adam Smith (adamsmith)]

This is a different bug from Fedora 825041 and so this should not be assigned to that bug.