Re: [Bug #15124] PCI host bridge windows ignored (works with pci=use_crs)

From: Bjorn Helgaas
Date: Wed Jan 27 2010 - 16:03:53 EST

On Wednesday 27 January 2010 01:50:12 pm Linus Torvalds wrote:
> On Wed, 27 Jan 2010, Bjorn Helgaas wrote:
> >
> > Without intel_bus.c, we essentially assume config 1 all the time.
> > If we keep intel_bus.c and this patch for .33, things should work
> > for configs 1 and 4. Adding support for config 4 is good.
> Quite frankly, is there any major downside to just disabling/removing
> intel_bus.c for 2.6.33? If we're not planning on having it in the long run
> anyway - or even if we are, but we can't be really happy about the state
> of it as it would be in 2.6.33, not using it at all seems to be the
> smaller headache.
> The machines that it helps are also the machines where you can fix things
> up with 'use_csr', no? And they are pretty rare, and they didn't use to
> work without that use_csr in 2.6.32 either, so it's not even a regression.
> Am I missing something?

Only that when we added intel_bus.c, Yinghai reported that the reason
was because a machine had a broken _CRS, so "pci=use_crs" wouldn't help.

At the time, Windows hadn't been brought up on that box. My
speculation is that by now, they've done that bringup and probably
fixed the _CRS issue, so it might work now.

If that's the case, we could drop intel_bus.c from .33 and just use
"pci=use_crs" on those boxes until we can figure out how to turn it
on automatically.

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