From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Olivier Galibert <galibert@pobox.com>
Subject: Re: [PATCH] update MMConfig patches w/915 support
Date: Mon, 22 Jan 2007 13:55:33 -0800
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Cc: linux-kernel@vger.kernel.org, Arjan van de Ven <arjan@infradead.org>
References: <200701071142.09428.jbarnes@virtuousgeek.org> <200701081327.16019.jbarnes@virtuousgeek.org> <20070116192800.GB4192@dspnet.fr.eu.org>
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On Tuesday, January 16, 2007 11:28 am, Olivier Galibert wrote:
> > But won't the bridge register value control what actually gets
> > decoded? If so, it sounds like this BIOS is buggy wrt mmconfig
> > mapping in general; good thing I'm not using any PCIe devices I
> > guess...
>
> Yeah.  I've checked the docs, I think I know what's going on.  On one
> hand, if the chipset is configured to have the range somewhere, it is
> decoded before anything external to the chipset, be it ram or mmaped
> i/o.  So the information you get from the chipset should not be able
> to conflict with anything by definition, it's the anything that
> wouldn't be visible.
>
> But in your case of a f0000000-ffffffff mapping, something else
> interesting is going on: it's conflicting with other internal
> registers of the chipset, which, being fixed address, probably have
> priority.  So you probably have to either reduce the range so that
> the chipset registers aren't touched, or drop mmconfig if the address
> is f0000000.
>
> Technically, we can have the exact same problem with the other
> chipsets.  BIOSen suck.

Ouch.  It doesn't seem like there's a sane general way to fix this up, 
aside from some sort of blacklist.  Maybe it's best to leave this 
particular bridge unsupported for now...

Thanks,
Jesse
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