Cannot set CPU frequency for 8th gen CPU

[Dave Green]

On Wed, 18 Jul 2018, at 8:31 PM, Dave Green wrote:

> If I disable 5 of the 6 
> cores in the BIOS then setting frequency as above is successful.

Further, when setting:

# sysctl debug.cpufreq.verbose=1

A different 11.1 amd64 system with a 2nd gen 4 core processor reports:

cpufreq: setting abs freq 2500 on est0 (cpu 0)
cpufreq: setting abs freq 2500 on est1 (cpu 1)
cpufreq: setting abs freq 2500 on est2 (cpu 2)
cpufreq: setting abs freq 2500 on est3 (cpu 3)

Whereas the 11.2 amd64 system with the 8th gen 6 core reports:

cpufreq: setting abs freq 2800 on est0 (cpu 1)
cpufreq: setting abs freq 2800 on est1 (cpu 2)
cpufreq: setting abs freq 2800 on est2 (cpu 3)
cpufreq: setting abs freq 2800 on est3 (cpu 4)
cpufreq: setting abs freq 2800 on est3 (cpu 5)

For the second (faulty) system cpu0 is conspicuously missing and may explain why frequency can only be set on that machine with all but one core disabled?