Hi,
On Mon, Oct 30, 2006 at 03:03:53PM -0800, Michael Blakeley wrote:
> I've recently been bitten by
> http://bugzilla.kernel.org/show_bug.cgi?id=7157 - I also have an HP
> nc6400, with bios F.05, and can't downgrade to F.03 because my CPU only
> became supported in F.05. While I'm waiting to see if HP will fix this
> problem in a future bios rev, I wondered why cpufreq needs any bios
> information in the first place?
>
> This is all well outside my technical expertise, so I'm sure that I'm
> misunderstanding the problem - but that's why I'm asking. Basically my
> question is: why can't cpufreq interrogate the CPU directly, in order to
> find out what sort of cpu frequency scaling it supports (SpeedStep in
> various flavors, PowerNow, and whatever else is out there in the wild)?
> Wouldn't that be more robust than relying on the bios to get it right?
Unfortunately, no -- it is not only a matter of the processor on whether CPU
frequency and voltage scaling is supported, but also a matter of the
motherboard. Not all combinations of frequencies and voltages which run
stable on one notebook may run well on a different notebook with the same
CPU. Therefore, such hardcoded table-based approaches are only available in
rare cases.
Dominik
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