Re: [PATCH rhel6-branch] PPC: strengthen PReP-picking algorithm (#877852)

[David Lehman]

On Wed, 2013-08-14 at 14:12 -0400, Will Woods wrote:
> pSeries-style systems can have multiple PReP partitions, as long as
> there's only one per disk. It's kind of like the x86 MBR that way.
>
> The current code in booty and platform.py *always* picks the first PReP
> partition, which will fail if if you have (e.g.) an OS already installed
> on /dev/sda and you're doing a new install onto /dev/sdb.
>
> This patch adds ppcBootloaderInfo.pickPReP(), which tries to find the
> best PReP partition to use according to the following rules:
> If we're creating a new PReP partition, use that;
> Otherwise, if there's a PReP partition already on the disk that
> contains /boot, use that;
> Failing that, use the first available PReP partition (as before).
>
> This should make mkofboot actually install yaboot into the correct PReP
> partition.
>
> IPSeriesPPC.bootDevice() has been changed to use this same algorithm, so
> the two of them will agree about what the boot device is.
>
> booty/ppc.py | 37 ++++++++++++++++++++++++++++++++-----
>  platform.py  | 11 ++---------
>  2 files changed, 34 insertions(+), 14 deletions(-)
>
> diff --git a/booty/ppc.py b/booty/ppc.py
> index 6f62071..401f505 100644
> --- a/booty/ppc.py
> +++ b/booty/ppc.py
> @@ -7,6 +7,35 @@ from bootloaderInfo import *
>  import iutil
>
> class ppcBootloaderInfo(bootloaderInfo):
> def pickPReP(self):
>    # if we created a new PReP partition, pick that
>    for a in self.storage.findActions(type="create", obj="format"):
>        if a.format.type == "prepboot":
>            return a.device
>    # otherwise, look at the existing PReP partitions.
>    prepdevs = []
>    for dev in self.storage.fsset.devices:
>        if (dev.format.type == "prepboot" and
>                dev.partedPartition.getFlag(parted.PARTITION_BOOT)):
>            prepdevs.append(dev)
>    # we'd prefer a PReP partition that's on the same disk as /boot.
>    try:
>        bootdisk = self.storage.mountpoints["/boot"].disk
>    except KeyError:
>        bootdisk = self.storage.rootDevice.disk
>    for dev in prepdevs:
>        if dev.disk == bootdisk:
>            return dev

I think this needs to account for either /boot or / being on md, so
something like this:

bootDevice = self.storage.mountpoints.get("/boot", 
                                          self.storage.rootDevice)
if hasattr(bootDevice, "disk"):
  bootdisks = [bootDevice.disk]
else:
  bootdisks = list(set([p.disk for p in bootDevice.parents]))

for dev in prepdevs:
  if dev.disk in bootdisks:
    return dev

The rest looks okay to me. Is there a corresponding blivet patch for
master?