linux-kernel - Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.

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Date:	Mon, 17 Dec 2007 00:23:53 +0100
From:	Pavel Machek <pavel@....cz>
To:	"David P. Reed" <dpreed@...d.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Rene Herman <rene.herman@...access.nl>
Subject: Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80
	on some AMD64x2 laptops, etc.

Hi!

> The process of safely making delicate changes here is beyond my 
> responsibility as just a user - believe me, I'm not suggesting that a risky 
> fix be put in .24.   I can patch my own kernels, and I can even share an 
> unofficial patch with others for now, or suggest that Fedora and Ubuntu add 
> it to their downstream.
>
> May I make a small suggestion, though.   If the decision is a DMI-keyed 
> switch from out-80 to udelay(2)  gets put in, perhaps there should also be 
> a way for people to test their own configuration for the underlying problem 
> made available as a script.   Though it is a "hack", all you need to freeze 
> a problem system is to run a loop doing about 1000 "cat /dev/nvram > 
> /dev/null"  commands.  If that leads to a freeze, one might ask to have the 
> motherboard added to the DMI-key list.

Can you freeze it by catting /dev/rtc, too? That may be significant,
because that is readable for group audio (at least on some
systems)... which would smell like "small security hole" to me.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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