Re: Laptops & CPU frequency

[Ducrot Bruno <poup@poupinou.org>]

On Wed, Jan 14, 2004 at 04:59:45AM +0000, Dave Jones wrote:
> On Sun, Jan 11, 2004 at 12:54:51PM -0500, Robert Love wrote:
>  > On Sun, 2004-01-11 at 12:44, Matthew Garrett wrote:
>  > 
>  > > Is there any realistic way of noticing this sort of change?
>  > 
>  > Sure.  That is how Speedstep works, right?  We have an interface for
>  > Speedstep, so the kernel knows about it.  We do not have an interface
>  > for the proprietary BIOS stuff, I assume, so the kernel is oblivious.
> 
> Speedstep support is one way right now. We tell the CPU "switch to this mode"
> and it does. What we don't know how to do in cpufreq is detect when someone pulls
> the power out, or plugs back in. BIOS SMM magick happens, and it all
> gets taken care of transparently without us having a clue that anything
> happened.
> 
> We *could* hook into the APM 'power source changed' notifiers, (and I
> guess ACPI has something similar somewhere). That should take care of things.
> 
>  > But if you had the docs, I suppose you could code a solution and tie it
>  > into the cpufreq code, just as we have proper support for Speedstep,
>  > Longrun, etc.
> 
> Of all the implementations I've played with (longhaul/powernow/speedstep-smi)
> speedstep is the only one that does funky shit with SMM. The others are quite
> dumb (and friendly) in comparison. (Ie, nothing happens on power source change)

I'm wondering if there is a need to get bios ownership like in
the speedstep-smi if not in acpi mode, in speedstep-ich? 

Anyway speedstep-ich should be fine if you explicitely configure BIOS
in order to boot always in high performance mode.

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.