kern/140361: [cpufreq] speed-stepping broken on PhenomII (acpi?)

Bruce Cran bruce at
Thu Mar 25 08:01:02 UTC 2010

On Wednesday 24 March 2010 10:30:04 Hannes wrote:
> The following reply was made to PR kern/140361; it has been noted by GNATS.
> From: Hannes <freebsd at>
> To: bug-followup at
> Cc:
> Subject: Re: kern/140361: [cpufreq] speed-stepping broken on PhenomII
> (acpi?) Date: Wed, 24 Mar 2010 10:27:34 +0000
>  *ping*
>  Is there anything I can do to help solve this issue?
>  (still there on a current RELENG_8)

I don't think powerd will change the Cx level by default, but it should change 
the frequency as reported by dev.cpu.X.freq where X is the CPU number. You 
should be able to have the Cx levels change by setting dev.cpu.X.cx_lowest to 
something other than C1, but I think you need to keep CPU 0 at C1 otherwise 
the system will stop working properly (timings will change).

See for more details.

Bruce Cran

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