Clocks broken on Mac mini

[Hugh Blemings]

Hi Hal,

On 31/01/2017 15:54, Hal Murray wrote:
>> 30 Jan 19:46:40 ntpd[3773]: frequency error 2712 PPM exceeds tolerance 500 PPM
>> clock           : 1416.666661MHz
>
> If the clock really is 1.42 GHz but the system thinks it is 1.416...
> My calculations say it's off by 2400 ppm
>
> That's the sort of glitch I've been looking for.
>
> The next question is where does 1416 come from?
> I think that's Open Firmware, but I don't know my way around there (yet?).

That's some excellent detective work - my guess is the 1.42GHz number 
Apple publicise is marketing rather than actual (ie they've rounded up 
to make the machine seem faster) but it's a good datapoint and maybe 
there is a correlation.  Interesting.

When I get some time later today/tonight I'll summarise what we have so 
far into a single email and send that off to the linux-ppc crew for 
comment, will copy you and list of course.

What's odd to me (though perhaps I misunderstand the finer points still) 
- is this presumably means that in the absence of ntp, Mac Mini G4s 
would, at least running this kernel, routinely have their system clocks 
running wrong (fast, I guess?)

Bear with me, will get a summary together once I finish a couple of work 
items.

Cheers,
Hugh