Re: [RFC 1/3] powernv/cpuidle : Support for pre-entry and post exit of stop state in firmware

[Nicholas Piggin]

Thanks for picking this up and pushing it along. I do plan to come back 
and take another look at it all, but what we do need to do first is get 
a coherent approach to this proposed new calling convention and OS ops.

It's fine to work on this in the meantime, but to start merging things
my idea is:

- OPAL must leave r13-r15 untouched for the OS.
- OS ops are made available only for a "v4" OS that uses the new
  calling convention, including kernel stack.
- OS ops baseline (all OSes must provide) will be console / printk 
  facility, trap handling and crash/symbol decoding on behalf of OPAL,
  and runtime virtual memory.

Other OS ops features can be added in the versioned structure, including 
this.

I'm trying to get back to cleaning these things up and start getting 
them merged now. Any comments or review on those would be helpful.

Thanks,
Nick