linux-kernel - DMAR:[fault reason 02] Present bit in context entry is clear (firewire-ohci)

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Date:	Sat, 22 May 2010 12:26:15 +0200
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	linux-pci@...r.kernel.org
CC:	linux1394-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: DMAR:[fault reason 02] Present bit in context entry is clear (firewire-ohci)

Hi,

I came across a report of the subject message.  What does it mean; what
type of bug should be look for?

https://bugzilla.redhat.com/show_bug.cgi?id=587178
>>>
firewire_ohci 0000:04:00.4: PCI INT C -> GSI 16 (level, low) -> IRQ 16
firewire_ohci 0000:04:00.4: setting latency timer to 64
firewire_ohci: Added fw-ohci device 0000:04:00.4, OHCI version 1.0
DRHD: handling fault status reg 2
DMAR:[DMA Read] Request device [04:00.0] fault addr fffff000
DMAR:[fault reason 02] Present bit in context entry is clear
DMAR:[DMA Read] Request device [04:00.0] fault addr fffff000
DMAR:[fault reason 02] Present bit in context entry is clear
DMAR:[DMA Read] Request device [04:00.0] fault addr fffff000
DMAR:[fault reason 02] Present bit in context entry is clear
<<<

The log sounds as if this happens during from-device DMA of 04:00.4 into
a consistent buffer, yet the fault is logged for device 04:00.0.  The
log is from a Dell M4500.  The devices are, according to a web search,
04:00.0 CardBus bridge [0607]: Ricoh Co Ltd Device [1180:e476] (rev 02)
04:00.4 FireWire (IEEE 1394) [0c00]: Ricoh Co Ltd Device [1180:e832]
(rev 03) (prog-if 10)

Thanks for any hint,
-- 
Stefan Richter
-=====-==-=- -=-= =-==-
http://arcgraph.de/sr/
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