Comment 95 for bug 1810239

I don't know if the DMAR errors I am receiving have anything to do with this thread. But I have been researching this problem & keeping abreast of the comments here, & just wanted to offer more insight & any support required.

These DMAR errors are occurring on my ASUS X79 Rampage IV Black Edition. It happens for the same reasons stated here (intel_iommu is set) but with a slightly different configuration. It happens with my Plextor SSD running on a Sonnet PCIe Adapter Card:

[ 1.504803] dmar: DRHD: handling fault status reg 2
[ 1.504806] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 1.844208] dmar: DRHD: handling fault status reg 102
[ 1.844488] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 1.997325] dmar: DRHD: handling fault status reg 202
[ 1.997327] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 7.003663] dmar: DRHD: handling fault status reg 302
[ 7.003949] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 7.322245] dmar: DRHD: handling fault status reg 402
[ 7.322515] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 7.475646] dmar: DRHD: handling fault status reg 502
[ 7.475917] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 12.481676] dmar: DRHD: handling fault status reg 602
[ 12.481962] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 12.800264] dmar: DRHD: handling fault status reg 702
[ 12.800535] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 12.953665] dmar: DRHD: handling fault status reg 2
[ 12.953935] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 17.959657] dmar: DRHD: handling fault status reg 102
[ 17.959944] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear
[ 18.278287] dmar: DRHD: handling fault status reg 202
[ 18.278558] dmar: DMAR:[DMA Write] Request device [0b:00.1] fault addr fffe0000
DMAR:[fault reason 02] Present bit in context entry is clear

There is no 0b:00.1 device. However, when I query pci devices for "0b", I get the following:

root [ ~ ]# lspci | grep -i 0b
0b:00.0 SATA controller: Marvell Technology Group Ltd. Device 9182 (rev 11)
ff:0b.0 System peripheral: Intel Corporation Xeon E7 v2/Xeon E5 v2/Core i7 UBOX Registers (rev 04)
ff:0b.3 System peripheral: Intel Corporation Xeon E7 v2/Xeon E5 v2/Core i7 UBOX Registers (rev 04)

I read somewhere that just removing iommu from the config, things should work fine. And, so they did. No DMAR errors. But, after reading comments here, I thought I would try to see if changing quirks.c would work for me. So, I turned on iommu in the config & modified quirks.c:

DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MARVELL_EXT, 0x9182,
                         quirk_dma_func1_alias);

and got the same DMAR errors I had been getting before I had any understanding that intel_iommu along with certain hw could cause some serious issues.

This site, & in particular, these postings have been a TREMENDOUS help to me. Thanks EVERYBODY!!!