Clocks broken on Mac mini

[Hugh Blemings]

Hi Hal, All,

Starting the day here :)

On 31/01/2017 05:53, Hal Murray wrote:
>> $ cat /proc/cmdline
> root=UUID=48d99649-90b2-4dc6-be05-5ca3858579a1 ro
>
>
> hugh at blemings.org said:
>> That sounds right for getting into OpenFirware - but for what we're  digging
>> into you shouldn't need to putz with it.
>
> It looks like the kernel code is getting the clock frequency from Open
> Firmware.  If that's off, it could lead to this sort of problem.

Yes - that's one possible scenario.

> The Intel version of Linux calibrates the TSC against one of the other clocks
> that is well specified, or at least constant in practice.

If I recall correctly the PowerPC definition requires the timebase in a 
PPC chip to be of constant frequency irrespective of power saving, clock 
modulation to minimize EMI and other such - so they're normally pretty 
well behaved.

I realised overnight, and I apologise - I should have asked you to run

$ uname -a

and

$ cat /etc/issue

as the /proc/cmdline entry didn't contain the kernel version - something 
we will definitely need.

One other query if I may - I think you've already confirmed this 
behaviour across a couple of physical machines ?  Just want to rule out 
a single errant bit of hardware - unlikely but not unknown :)

Cheers,
Hugh