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

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Message-ID: <CABPqkBSpgYO9nxL67mmEOSg7tgssey4_ikdF_8-Vxn7u92suGg@mail.gmail.com>
Date:	Thu, 24 Apr 2014 11:41:17 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Aaron Lu <aaron.lu@...el.com>,
	Linux PCI <linux-pci@...r.kernel.org>, x86 <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Zheng Z Yan <zheng.z.yan@...el.com>,
	Dave Jones <davej@...hat.com>, Rui Zhang <rui.zhang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH 2] PNP: Work around BIOS defects in Intel MCH area reporting

On Thu, Apr 24, 2014 at 9:20 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Stephane Eranian <eranian@...gle.com> wrote:
>
>> On Tue, Apr 22, 2014 at 12:17 AM, Bjorn Helgaas <bhelgaas@...gle.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@...gle.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.
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