Re: PCI memory allocation bug with CONFIG_HIGHMEM

From: Andi Kleen
Date: Tue Jan 06 2004 - 10:37:08 EST


On Tue, Jan 06, 2004 at 07:27:33AM -0800, Linus Torvalds wrote:
>
>
> On Tue, 6 Jan 2004, Andi Kleen wrote:
> >
> > In my opinion it would have been cleaner if the aperture had always
> > an reserved entry in the e820 map.
>
> That does sound like a bug in the AGP drivers. It shouldn't be hard at all
> to make them reserve their aperture.
>
> Hint hint.

No, it's a bug in the BIOS that they're not marked. But I've actually
seen a BIOS that marked it and it lead to the Linux AGP driver failing
(due to some interaction with how setup.c sets up resources). So the Linux
driver currently even relies on the broken state.

Anyways, I already implemented reservation for the aperture for the K8
driver some time ago. And it's in your tree. But it doesn't help for
finding IO holes because there could be other unmarked hardware lurking
there ... Or worse there is just no free space below 4GB.

-Andi
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