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Subject: Re: [PATCH] Don't touch BARs of host bridges
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Maciej W. Rozycki" <macro@mips.com>
Cc: Greg KH <greg@kroah.com>, Linux Kernel list <linux-kernel@vger.kernel.org>,
       Chris Dearman <chris@mips.com>,
       "Maciej W. Rozycki" <macro@linux-mips.org>
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Date: Fri, 10 Dec 2004 15:46:38 +1100
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On Fri, 2004-12-10 at 00:20 +0000, Maciej W. Rozycki wrote:
> Hello,
> 
>  BARs of host bridges often have special meaning and AFAIK are best left 
> to be setup by the firmware or system-specific startup code and kept 
> intact by the generic resource handler.  For example a couple of host 
> bridges used for MIPS processors interpret BARs as target-mode decoders 
> for accessing host memory by PCI masters (which is quite reasonable).  

Not very reasonable in fact imho but that happens on some embedded PPCs
was well :) So I agree, that would be useful to skip them. I'm not sure
about PCI_CLASS_NOT_DEFINED tho ...