[colug-432] How can I tell what driver cpu scaling uses?

[Rob Funk]

Joshua Kramer wrote:
> I have an HP laptop that I just re-installed CentOS 6 on.  Using the stock
> 2.6 kernel, 95% of the hardware works.  However, if I use a 3.1 kernel, 99%
> of the hardware works.  Almost.
> 
> With the 3.1 kernel, I cannot start cpuspeed.  It cannot write to the file
> 
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> 
> With the 2.6 kernel, cpuspeed runs just fine.
> 
> I'm guessing that the 3.1 kernel provided by elrepo doesn't have the right
> cpu speed scaling drivers compiled in.  Does anyone know how I can tell
> which driver the 2.6 kernel uses for this, so I can build it for the 3.1
> kernel?

You might want to go newer than 3.1, since that dates back to Oct
2011. They're up to 3.12 now.

I did a google search for cpufreq on kernelnewbies.org, and found that
kernel 3.7 added a generic cpufreq driver and kernel 3.9 added a
cpufreq driver for last year's cpus.

It might also help to specify the specific 2.6 version (the earliest
ones are ten years old) and the HP laptop model or vintage.