On Tue, 2014-05-06 at 16:37 -0400, John Baldwin wrote: > On Tuesday, May 06, 2014 2:08:35 pm Adrian Chadd wrote: > > On 5 May 2014 13:57, John Baldwin <[email protected]> wrote: > > > > > The user in question found this on 9-stable with the existing defaults as > > > the > > > HPET was just plain broken on their system and that was unrelated to Cx > > > states. > > > (Rather, Cx states were only involved because worries about them are why > > > the > > > system chose to use HPET. Had Cx states been enabled by default, they > > > would > > > have had to disable those as well in addition to forcing LAPIC instead of > > > HPET.) > > > > Hm. Sounds uncomfortable. How does Windows run on systems like this? > > Do the windows drivers just disable HPET and use LAPIC or worse for > > timing, and just ignore anything lower than C1? > > I have no idea. Maybe they use the RTC. :-/ Maybe the HPET on these systems > works if you use it "sparingly". I believe OS X might have only used the HPET > to provide the "missing" LAPIC wakeups when entering Cx for example. (Our > current > eventtimer system wants to always use whichever timer it picks, not switch off > between them.) >
The eventtimer code is happy to switch between timers on the fly, but iirc the only interface to that feature is sysctl. I found it fairly easy to add an in-kernel API for changing the frequency of the current timer on the fly. I think it would be just as easy to add a kernel call to change timers as well. -- Ian _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-acpi To unsubscribe, send any mail to "[email protected]"
