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

Stephane Eranian
2014-04-24T09:41:23Z

On Thu, Apr 24, 2014 at 9:20 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * 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?
>
In my case, it was just the warning. Everything appeared to worked correctly.