powerpc power management

[John Rigby]

> Generally the issue is not with getting the processor into sleep mode,
> it's how you poke the rest of the system to put the RAM into
> self-refresh mode, power down external buses, etc.  That stuff tends
> to be very platform-specific.
Yes you are right, I was asking about the cpu core not all the
external devices.  I realize that the majority of the code is in the
rest of the system.