On Fri, Feb 06, 2015 at 11:36:12PM +0100, Rafael J. Wysocki wrote:

On Friday, February 06, 2015 07:29:22 PM Peter Zijlstra wrote:

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So I'm a wee bit confused; if we use an enter_freeze() state that keeps
interrupts disabled; who is going to call the freeze_wake() thing?

Ah, I think I see, so we wake up, keep the interrupt pending, re-enable
the tick and time and everybody, then re-enable interrupts, take the
interrupt and go around the idle loop to find we need a reschedule etc..

Exactly.

So x86 mwait can do this; what other archs can 'sleep' and keep
interrupts disabled?

It looks like the ARM WFI thing wakes on pending interrupts and doesn't
actually require interrupts to be enabled, so that too would work.