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Date: Wed, 24 Jun 2009 16:37:05 -0700
From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>, Ingo Molnar <mingo@elte.hu>,
       Gary Hade <garyhade@us.ibm.com>, Matthew Wilcox <matthew@wil.cx>,
       Larry Finger <Larry.Finger@lwfinger.net>,
       Andrew Morton <akpm@linux-foundation.org>, linux-pci@vger.kernel.org,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Jaswinder Singh Rajput <jaswinder@kernel.org>
Subject: Re: [PATCH] x86/pci: don't use crs for root if we only have one
 root bus
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On Wed, 24 Jun 2009 16:21:09 -0700 (PDT)
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> 
> 
> On Wed, 24 Jun 2009, Linus Torvalds wrote:
> >
> > I'm happy to apply various patches to fix it up, but regardless, I
> > thinkwe should revert that commit as bogus. We can try making it
> > the default again next round, when maybe it will be true that it
> > doesn't cause issues.
> 
> Btw, I really think our _CRS handling sucks.
> 
> There's two things that you can do with _CRS:
> 
>  - use the _existence_ of it as an indicator of a root bus
> 
>  - try to use it to populate the resource tree.
> 
> And quite frankly, I think #2 is broken. There's no way in hell that
> ACPI tables are ever going to be better than just asking the
> hardware. We've gone through this before. Trusting ACPI over the
> hardware is just FUNDAMENTALLY WRONG.
> 
> So I'm just going to do that revert. I'm not sure if it ever makes
> sense to make that insane _CRS code the default. It seems like a
> fundamentally flawed idea.

Yeah, I think it's reasonable to revert, especially given how we do
_CRS handling currently.  I'm hoping at some point we can use the _CRS
data to at least augment the configuration we get from hardware, since
on some machines it seems to be necessary.

-- 
Jesse Barnes, Intel Open Source Technology Center
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