2.6.28-rc1: NVRAM being corrupted on ppc64 preventing boot (bisected)

[Josh Boyer]

On Fri, Oct 31, 2008 at 07:52:02AM +1100, Paul Mackerras wrote:
>Mel Gorman writes:
>
>> On some ppc64 machines, NVRAM is being corrupted very early in boot (before
>> console is initialised). The machine reboots and then fails to find yaboot
>> printing the error "PReP-BOOT: Unable to load PRep image".  It's nowhere near
>> as serious as the ftrace+e1000 problem as the machine is not bricked but it's
>> fairly scary looking, the machine cannot boot and the fix is non-obvious. To
>> "fix" the machine;
>> 
>> 1. Go to OpenFirmware prompt
>> 2. type dev nvram
>> 3. type wipe-nvram
>> 
>> The machine will reboot, reconstruct the NVRAM using some magic and yaboot
>> work again allowing an older kernel to be used. I bisected the problem down
>> to this commit.
>
>Eek!
>
>Which ppc64 machines has this been seen on, and how were they being
>booted (netboot, yaboot, etc.)?
>
>Is it just the Powerstations with their SLOF-based firmware, or is it
>IBM pSeries machines as well?

I'm pretty sure it was with pSeries machines.  I saw reports of POWER5
being effected (p520 and p710).  I believe one of them resolved the
issue by upgrading firmware on the machine.

josh