linux-kernel - Re: [patch, take 3] PCI: use ACPI to verify extended config space on x86

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Date:	Fri, 14 Jul 2006 16:15:41 +0200
From:	Andi Kleen <ak@...e.de>
To:	Chuck Ebbert <76306.1226@...puserve.com>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	linux-pci <linux-pci@...ey.karlin.mff.cuni.cz>,
	Greg KH <greg@...ah.com>, Andrew Morton <akpm@...l.org>,
	"Brown, Len" <len.brown@...el.com>,
	Rajesh Shah <rajesh.shah@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [patch, take 3] PCI: use ACPI to verify extended config space on x86

On Friday 14 July 2006 15:57, Chuck Ebbert wrote:
> In-Reply-To: <1152869988.3159.25.camel@...topd505.fenrus.org>
> 
> On Fri, 14 Jul 2006 11:39:48 +0200, Arjan van de Ven wrote:
> 
> > > Extend the verification for PCI-X/PCI-Express extended config
> > > space pointer. Checks whether the MCFG address range is listed
> > > as a motherboard resource, per the PCI firmware spec.
> > 
> > I'm still not quite happy about this; the entire point of the check is
> > that we CAN'T trust the ACPI implementation, and want a second opinion.
> > This patch basically asks the ACPI implementation if we can trust the
> > ACPI implementation. I'm not sure that's a good idea.
> > And I understood that most issues went away with the more relaxed check
> > that is in gregkh's tree already (if not in mainline, I should check
> > that). 
> 
> The more-relaxed check is in mainline.  I wrote it, but it didn't even
> fix the problem on my own machine. 

Why did you submit it then when it didn't work?

> This did. 
> 
> According to Rajesh, the spec doesn't require the MCFG space to be
> e820-reserved, so that's not really a valid check.

Anyways Rajesh's patch is probably the way to go. If the ACPI
implementatin is self consistent it can be probably trusted.

The e820 check was just a heuristic and it clearly wasn't a good one. 

-Andi
 
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