Re: About p4-clockmod breakage/removal

[Len Brown <lenb@kernel.org>]

On Friday 09 May 2008, Alex Villací­s Lasso wrote:
> In a somewhat old computer I use at home, I have a Pentium 4 CPU running 
> at 1.7GHz. On this computer, acpi-cpufreq does not work (modprobe fails 
> with -ENODEV), only p4-clockmod. Lately this means I have to compile my 
> own kernel to get speed throttling on my computer.
> 
> Recently, patch ed9cbcd40004904dbe61ccc16d6106a7de38c998 (Revert 
> "speedstep-lib.c: fix frequency multiplier for Pentium4 models 0&1") 
> broke clock speed reporting. It now reports I have a max speed of 13.80 
> GHz instead of 1.7GHz. I only wish my CPU were that fast... Reverting 
> this patch fixes the problem for me. However, since I suscribed 
> yesterday to this list, I see talk about removing p4-clockmod altogether 
> from the tree. Maybe my real problem is that acpi-cpufreq does not work 
> even though it should, but I have yet to find a way to make the module 
> print the information that is supposed to be displayed through dprintk() 
> messages. What else can I do to debug acpi-cpufreq on my machine?

Assuming this is a laptop with a batter,
I'd certainly be interested if you could run BLTK
and measure any benefit to p4-clockmod (I've never
been able to)

http://www.lesswatts.org/projects/bltk/

Re: acpi-cpufreq
Verify that you're running the latest BIOS,
and look in BIOS SETUP for any options related
to CPU power management, Speed Step, EIST, P-states etc,
and enable if present.

If that doesn't do it, then open a bug here
complaining that acpi-cpufreq doesn't load:

http://bugzilla.kernel.org/enter_bug.cgi?product=ACPI

and attach the output from acpidump -- which will tell
us if the underlying BIOS support is present.
My guess is that it is not.

-Len

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