System clock falls behind quickly on Mac mini G4
John Baldwin
jhb at freebsd.org
Tue Apr 8 14:41:49 UTC 2014
On Tuesday, April 08, 2014 10:29:29 am Alexey Dokuchaev wrote:
> On Mon, Apr 07, 2014 at 05:04:58PM -0400, John Baldwin wrote:
> > Also, if the frequency is calibrated incorrectly during boot for some reason,
> > your time-of-day clock will drift constantly. I've seen this on x86 boxes
>
> Yes, I remember a thread (x86ish) some time ago about bogus TSC calibration,
> but...
>
> > where the TSC was calibrated incorrectly due to an interaction with SMM
> > interrupts for legacy USB emulation. In that case, adjusting machdep.tsc_freq
> > to match the frequency from the CPU's brand string "fixed" the drift.
>
> ... sysctl -a does not show machdep.tsc_freq for me on this G4 box for
> some reason (GENERIC kernel).
It wouldn't be tsc_freq on a powerpc box. You'd need to see what your timecounter
is and what frequency it is using (kern.timecounter nodes) and see if that is
adjustable.
--
John Baldwin
More information about the freebsd-ppc
mailing list