Subject: Re: BAR 0: can't allocate resource
From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: Alex Brooks <a.brooks@marathon-robotics.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
In-Reply-To: <201001071209.01975.a.brooks@marathon-robotics.com>
References: <201001061305.31635.a.brooks@marathon-robotics.com>
	 <201001061316.21744.a.brooks@marathon-robotics.com>
	 <201001061319.54436.bjorn.helgaas@hp.com>
	 <201001071209.01975.a.brooks@marathon-robotics.com>
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Date: Wed, 06 Jan 2010 22:46:16 -0700
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On Thu, 2010-01-07 at 12:09 +1100, Alex Brooks wrote:
> > You mentioned two messages.  Here's the first:
> >   PCI: BIOS Bug: MCFG area at e0000000 is not reserved in ACPI motherboard
> > resources PCI: Not using MMCONFIG.
> >
> > and the second:
> >   PCI: Cannot allocate resource region 0 of device 0000:01:04.0
> >   PCI: Error while updating region 0000:01:04.0/0 (feb00002 != 00000000)
> >
> > The "Error while updating region" message is because we wrote something
> > to a BAR, read it back, and they didn't match.  I suppose this could be
> > some kind of config space problem related to the fact that we're not
> > using MMCONFIG.
> >
> > Can you try removing the MCFG reservation check, so we do try to use
> > MMCONFIG?  If you do this on a current kernel, we'll also get a little
> > more debug output about the subsequent resource allocation failure.
> 
> I did this on my 2.6.26 kernel (is this current enough or would a later kernel 
> be better?) and attached the dmesg output.

Looks like you got the same errors when accessing config space as
before.

I was hoping for a kernel directly from Linus' git repo, e.g.,
2.6.33-rc3; I don't think the debug output I'm thinking about went in
until after 2.6.32 was released.

Bjorn


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