Re: [PATCH] x86/pci: don't use crs for root if we only have oneroot bus

From: Jesse Barnes
Date: Wed Jun 24 2009 - 19:37:23 EST


On Wed, 24 Jun 2009 16:21:09 -0700 (PDT)
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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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