Re: 3.2rc1: bootup fails: DRHD: handling fault status reg 2

From: Robert Hancock
Date: Mon Nov 14 2011 - 23:33:45 EST


On 11/14/2011 06:53 PM, Arnd Hannemann wrote:
Hi,

Am 14.11.2011 23:33, schrieb Arnd Hannemann:

when trying to boot kernel 3.2rc1 on my thinkpad t510 I get an endless loop of errors:

DRHD: handling fault status reg 2
DMAR: [DMA Read] Request device [0d:00.0] fault addr fffff000
DMAR: [fault reason 02] Present bit in context entry is clear

screenshot can be found here:
http://arndnet.de/lkml/screenshot3.2rc1.jpg

kernel 3.1.1 is booting up flawlessly.

I must have inadvertently enabled CONFIG_INTEL_IOMMU_DEFAULT_ON in my config
for 3.2-rc1.

With disabled CONFIG_INTEL_IOMMU_DEFAULT_ON my thinkpad boots up again.
Not sure if this is expected?

No, that's not supposed to happen. Can you post the output of "lspci -vv"? Apparently that device 0d:00.0 is generating unexpected DMA accesses for some reason.
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