Re: PCI-DMA: high address but no IOMMU

From: Nish Aravamudan
Date: Thu Oct 27 2005 - 12:57:25 EST


On 10/27/05, Michael Madore <michael.madore@xxxxxxxxx> wrote:
> Hi,
>
> I am seeing the following errors in /var/log/messages when booting
> 2.6.14-rc5 on a dual Opteron nforce4 motherboard with 8GB of RAM:
>
> Checking aperture...
> CPU 0: aperture @ be8c000000 size 32 MB
> Aperture from northbridge cpu 0 too small (32 MB)
> No AGP bridge found
> Your BIOS doesn't leave a aperture memory hole
> Please enable the IOMMU option in the BIOS setup
> This costs you 64 MB of RAM
> Mapping aperture over 65536 KB of RAM @ 8000000
>
> ...
>
> PCI-DMA: Disabling AGP.
> PCI-DMA: More than 4GB of RAM and no IOMMU
> PCI-DMA: 32bit PCI IO may malfunction.<6>PCI-DMA: Disabling IOMMU.

I get the same message on my 2-way Opteron machine (ASUS K8N-DL mobo),
but I only have 2 GB of RAM :/ Seems odd the PCI-DMA subsystem thinks
I have more than 4 :) Anybody have any ideas?

Thanks,
Nish
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