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

From: Pavel Machek
Date: Sun Dec 16 2007 - 18:24:14 EST


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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