Re: PCI-DMA: high address but no IOMMU - nForce4

[Andreas Kleen]

[full quote]
Â
Am Di 01.11.2005 06:21 schrieb Marc Perkel <marc@xxxxxxxxxx>:

> > On Fri, Oct 28, 2005 at 12:16:51AM +0200, Andi Kleen wrote:
> >
> > I will attach my own; A brand new Amd64 dual-core thing.
> > Works fine with mem=2500M, but blows up with mem=3G or
> > without any override and full 4G complement in use.
> >
> > This board (ASUS A8N-SLI) does use NVIDIA nForce4 chipset with
> > bios-option to map (hoist) "excess memory" out from first 4G to
> > higher physical addresses so that it can be accessed by the
> > processor.
> >
> > This board has no AGP at all in it, but it does have lots
> > of PCIE, and a bit of PCI-X thrown in for "legacy cards".
> > Somehow that detail breaks things when the machine really
> > should use bounce-buffering, or something similar -- I don't
> > know if Nvidia nForce4 chipset does have IOMMU, though...
> >
> > If Nvidia did omit such essential piece of hardware from
> > a modern chipset, I do find it amazingly short-sighted...
> > (Of course they don't yield documentation of the chips to
> > public so that I can't quickly verify this detail...)
>
>
> For what it's worth I have almost the exact same hardware and got the
> same
> error. Athlon X2 4400 with the same ASUS board. Reverting to 2.6.13.2
> kernel works.
>

Â
This sounds like the PCI-X BIOS misconfiguration issue that Andy C.
recently
tracked down. Andy do you agree?
Â
If yes it's a BIOS problem, but we can probably work around it with a
quirk.
Â
-Andi

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