Re: PCI memory allocation bug with CONFIG_HIGHMEM

From: Andi Kleen
Date: Tue Jan 06 2004 - 04:44:51 EST


On Tue, Jan 06, 2004 at 11:11:21AM +0200, Mika Penttil? wrote:
>
>
> Andi Kleen wrote:
>
> >>If you ahve a proper e820 map, then it should work correctly, with
> >>anything that is RAM being marked as such (or being marked as "reserved").
> >>
> >>
> >
> >Every e820 map i've seen did not have the AGP aperture marked reserved.
> >
> Why should it? It's not ram, and the aperture is marked as reserved
> while doing PCI resource assignment/reservation.

It implies that you cannot just put your IO mappings
into any holes. Because something else like the aperture may
be already there.

In my opinion it would have been cleaner if the aperture had always
an reserved entry in the e820 map. Or better all usable holes get
an special entry. Then you could actually reliable allocate IO space
on your own. Currently it's just impossible.

-Andi
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