linux-kernel - Re: e_powersaver driver considered DANGEROUS (was Re: Linux 2.6.30-rc8 [also: VIA Support])

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Message-ID: <20090608061231.GB1444@ucw.cz>
Date:	Mon, 8 Jun 2009 08:12:31 +0200
From:	Pavel Machek <pavel@....cz>
To:	Harald Welte <HaraldWelte@...tech.com>
Cc:	"Michael S. Zick" <lkml@...ethan.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Duane Griffin <duaneg@...da.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: e_powersaver driver considered DANGEROUS (was Re: Linux
	2.6.30-rc8 [also: VIA Support])

Hi!

> > > Ah, but we are talking here of the *second* NetBook ever produced.
> > > If one is to believe the dmidecode output - it is using the VIA demo board
> > > BIOS. 
> > > 
> > > I bet the demo board BIOS is intended to demo the features of the product -
> > > not the correctness or completeness of the ACPI support.  ;)
> 
> So I've just been told the VIA reference BIOS has full support for the
> processor p-state support.  I'd therefore suppose every production BIOS
> contains that code, too.  The kernel should never use a native driver such as
> e_powersaver on any C7 or Nano system, but use the ACPI provided
> tables/methods, which are intel compatible.  A native driver would only be
> needed on really old C3 systems. 
> 
> The e_powersaver.c driver neither respects the maximum/minimum frequency
> constraints specified in the MSR's, nor does it take care of the inflection
> ratio, parallax and other advanced stuff that C7 and Nano are doing in this
> area.

Uhuh, what is inflection ratio/parallax?

I did play with cpufreq on intel/amd systems, and never heard about
those...

								Pavel

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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