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Date:   Tue, 28 Apr 2020 11:08:54 +1000
From:   Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [RFC 1/3] powernv/cpuidle : Support for pre-entry and post exit
 of stop state in firmware
To:     Abhishek Goel <huntbag@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org
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        oohall@gmail.com, psampat@linux.ibm.com, svaidy@linux.ibm.com,
        skiboot@lists.ozlabs.org
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Thanks for picking this up and pushing it along. I do plan to come back=20
and take another look at it all, but what we do need to do first is get=20
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=20
  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=20
this.

I'm trying to get back to cleaning these things up and start getting=20
them merged now. Any comments or review on those would be helpful.

Thanks,
Nick