2005-10-31 17:50:52

by Allen Martin

[permalink] [raw]
Subject: RE: PCI-DMA: high address but no IOMMU - nForce4

> 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...)

nForce4 does not contain an IOMMU, neither does any K8 chipset, because
the IOMMU is in the CPU.

-Allen