Atom N450 + C3 + HPET == bad timer behaviour

Adrian Chadd adrian at
Thu Jun 20 23:45:50 UTC 2013


I'm having issues with HPET + C3 state on this Atom N450 based
netbook. This is (shocking, I know!) running -HEAD (r251605.)

If I use C2, HPET is fine.

If I use RTC, i8254, LAPIC, C3 is also fine.

But C3 + HPET results in multi-second pauses where it should be 1 second.

I've disabled powerd and verified that dev.cpu.0.freq=1667; so it's
not CPU frequency related.

Doug found this: apparently SMI + timer fondling doesn't quite work out?



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