linux-kernel - RE: [discuss] Re: Please pull x86-64 bug fixes

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Message-ID: <1449F58C868D8D4E9C72945771150BDF46F8FD@SAUSEXMB1.amd.com>
Date:	Fri, 6 Oct 2006 17:31:46 -0500
From:	"Duran, Leo" <leo.duran@....com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Linus Torvalds" <torvalds@...l.org>
cc:	"Arjan van de Ven" <arjan@...radead.org>,
	"Jeff Garzik" <jeff@...zik.org>, "Andi Kleen" <ak@...e.de>,
	discuss@...-64.org, linux-kernel@...r.kernel.org
Subject: RE: [discuss] Re: Please pull x86-64 bug fixes

OK, lets' take K8 processor performance states (p-states) as an example:
BIOS, which should know 'best' about a given platform, needs to
communicate to the OS what 'voltage' (VID code) is correct for given
'frequency' (FID),
and it can do that via ACPI processor tables (_PSS). Otherwise, OS code
is left with having to manage a HUGE amount 'specifics' (processor
models), and endless driver revisions to account for new parts.

So, one can argue that there's merit on having ACPI, it's just a shame
when BIOS doesn't get it right! (thus the justification for lack of
'trust'... the same can probably be said about other BIOS issues, not
just ACPI)

Leo Duran


-----Original Message-----
From: Rafael J. Wysocki [mailto:rjw@...k.pl] 
Sent: Friday, October 06, 2006 5:01 PM
To: Linus Torvalds
Cc: Arjan van de Ven; Jeff Garzik; Andi Kleen; discuss@...-64.org;
linux-kernel@...r.kernel.org
Subject: Re: [discuss] Re: Please pull x86-64 bug fixes

On Friday, 6 October 2006 18:07, Linus Torvalds wrote:
> 
> On Fri, 6 Oct 2006, Arjan van de Ven wrote:
> >
> > we can do a tiny bit better than the current code; some chipsets
have
> > the address of the MMIO region stored in their config space; so we
can
> > get to that using the old method and validate the acpi code with
that.
> 
> Yes. I think trusting ACPI is _always_ a mistake. It's insane. We
should 
> never ask the firmware for any data that we can just figure out
ourselves.
> 
> And we should tell all hardware companies that firmware tables are
stupid, 
> and that we just want to know what the hell the registers MEAN!
> 
> I've certainly tried to tell Intel that. I think they may even have
heard 
> me occasionally.
> 
> I can't understand why some people _still_ think ACPI is a good idea..

I violently agree.

Rafael


-- 
You never change things by fighting the existing reality.
		R. Buckminster Fuller





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