Re: PCI-DMA: high address but no IOMMU (still there)

[Alex Bligh - linux-kernel]

--On 27 October 2005 10:47 -0700 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:

For the record, I was seeing the same problem with 2.6.15-rc5 (it
wasn't there on 2.6.12), but the thread I'm replying to isolated the
problem patch.

A workaround here (Phoenix BIOS, Dual Opteron 275, 8GB RAM, 1.02.2895,
Tyan Thunder K8WE (S2895)) is to set the following in BIOS:

* Set Operating System to "Linux"
* Hammer Configuration->Memory Hole->IOMMU set to Enable
* Hammer Configuration->MTRR mapping set to "Discrete"

No idea why this fixes it, nor why it wasn't necessary before,
but it at least boots now.

It hangs in a pretty cryptic way on a default config kernel (well, Ubuntu
Dapper defaults) so it would be nice if this was resolved.

--
Alex Bligh
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