> > > I guess we could also be busy-looping waiting for the event, but it
> > > would not be nice to other guests domains.
> > 
> > if there's a way to poll events (i couldn't find any),
> > i think it's better to use it because ddb needs to do busy-loop anyway.
> 
> Not here, xenconscn_getc() calls HYPERVISOR_yield() when it waits for
> input, so it won't consume CPU. But HYPERVISOR_yield() won't return unless
> interrupts are enabled.

"interrupts" in what sense?
i thought HYPERVISOR_yield left the calling domain runnable
so it would be scheduled sooner or later.

YAMAMOTO Takashi