[RFC/PATCH] powerpc: Use rtas query-cpu-stopped-state in smp spinup
ntl at pobox.com
Wed Apr 5 03:25:50 EST 2006
Michael Ellerman wrote:
> Currently we use a cpumask called of_spin_map to keep track of which threads
> have been spun up. We basically guess that OF has spun up all even numbered
> threads, and so all the odd numbered threads need to be brought up.
> That's a bit of a dicey assumption at best, and is totally incorrect for
> Luckily we have an rtas call which can tell us whether a cpu is up
> or not, so let's use it?
1. query-cpu-stopped-state isn't available on all RTAS systems (I
believe it's required only on systems that support cpu offline).
2. I've tried it before. Hope I'm remembering this correctly, but I
think my experience was that query-cpu-stopped-state reported
nonsense for cpus that were started by OF. This was on Power5,
3. This isn't how query-cpu-stopped-state was intended to be used.
It's meant to be used by the OS to determine when a thread has
stopped itself using the stop-self method. Which might partially
I'm fine with getting rid of the assumptions about thread numbering,
but I don't think this is gonna work, sorry.
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