On Tue, Jul 15, 2008 at 03:34:42PM -0700, David Brownell wrote:
> > > > We can resolve the problem in userspace. I can imagine
> > > > hwclock(8) that reads /sys/class/rtc/rtc0/settime_offset_ms
> >
> > That'd work. Someone would need to provide the kernel patch
> > to define that value, with whatever units are relevant. In
> > most cases the value would be zero, but rtc-cmos would need
> > to export 500 msec.
>
> By the way ... I just happened to be looking at how the
> HPET (available on modern x86 systems, and solidly in the
> Linux "should use" category) interacts with the RTC.
>
> Capsule summary: absolutely nothing keeps the emulated RTC
> IRQs (arch/x86/kernel/hpet.c) in phase with the real RTC.
>
> So any effort to pay attention to that 500 msec delay is
> going to be monitoring the HPET IRQs instead of the real
> RTC signals. The right offset would rarely be 500 msec.
Does it mean that /sys/class/rtc/rtc0/settime_offset_ms
is nonsense?
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
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