Re: [PATCH] x86, HPET: ignore any PCI BARs that match an HPET wealready know about

From: H. Peter Anvin
Date: Wed Sep 22 2010 - 18:11:44 EST


On 09/22/2010 02:52 PM, Bjorn Helgaas wrote:
>
> We don't necessarily need to slavishly copy what Windows does, but
> I'd feel better if we understood how it avoided the problem on the
> Gigabyte board so we could make a more informed decision.
>
> It really doesn't look like Windows, and therefore BIOS writers,
> share your expectations about PCI BARs in E820 reserved areas.
> It's likely still *safe* to make them fixed resources, but we might
> be able to fix more issues if we knew how Windows avoids the problem.
>

Keep in mind that Windows -- the version they tested against -- might
just work by accident. That's a "ship it" condition for the BIOS for
almost every vendor.

Also, do note that the reservations don't necessarily need to come from
the BIOS; we can mark the HPET area internally reserved, for example,
when we discover it.

-hpa

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