Re: [PATCH 2] PNP: Work around BIOS defects in Intel MCH area reporting

Ingo Molnar
2014-04-24T07:20:28Z

* Stephane Eranian <eranian@google.com> wrote:

> On Tue, Apr 22, 2014 at 12:17 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> > Work around BIOSes that don't report the entire Intel MCH area.
> >
> > MCHBAR is not an architected PCI BAR, so MCH space is usually reported as a
> > PNP0C02 resource. The MCH space was once 16KB, but is 32KB in newer parts.
> > Some BIOSes still report a PNP0C02 resource that is only 16KB, which means
> > the rest of the MCH space is consumed but unreported.
> >
> > This can cause resource map sanity check warnings or (theoretically) a
> > device conflict if we assigned the unreported space to another device.
> >
> > The Intel perf event uncore driver tripped over this when it claimed the
> > MCH region:
> >
> > resource map sanity check conflict: 0xfed10000 0xfed15fff 0xfed10000 0xfed13fff pnp 00:01
> > Info: mapping multiple BARs. Your kernel is fine.
> >
> > To prevent this, if we find a PNP0C02 resource that covers part of the MCH
> > space, extend it to cover the entire space.
> >
> Works for me on my Levono IvyBridge laptop.
> Thanks for fixing this, Bjorn.
> Acked-by: Stephane Eranian <eranian@google.com>

Just curious, what problems triggered on your laptop: only the
warnings, or did something get mapped to the undeclared area,
causing other misbehavor?

Thanks,

Ingo