# DMA R DRHD errors and intel_iommu=igfx_off

## ppeetteerr

I Just installed Gentoo on an acer timeline 3810tz with a Intel GMA 4500MHD graphics card and was running into two problems the first was random kernel freezes at the very start of my boot sequence. It would display ffffff and whatever the error message was. It would occasionally boot and I would get the messages below.  I finally added intel_iommu=igfx_off which seems to have fixed both problems.  I have no clue what it did other than the error was comming from y graphics card. I know DMA is a technique used to reduce the load on a CPU. Any clue what performance hit I'll take after disabling it? Also when will it be supported?

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Dec  3 22:15:11 ECKO kernel: DRHD: handling fault status reg 3

Dec  3 22:15:11 ECKO kernel: DMAR:[DMA Write] Request device [00:02.0] fault addr b9800000

Dec  3 22:15:11 ECKO kernel: DMAR:[fault reason 05] PTE Write access is not set

Dec  3 22:15:11 ECKO kernel: DRHD: handling fault status reg 3

Dec  3 22:15:11 ECKO kernel: DMAR:[DMA Write] Request device [00:02.0] fault addr b9800000

Dec  3 22:15:11 ECKO kernel: DMAR:[fault reason 05] PTE Write access is not set

Dec  3 22:15:11 ECKO kernel: DRHD: handling fault status reg 3

Dec  3 22:15:11 ECKO kernel: DMAR:[DMA Write] Request device [00:02.0] fault addr b9800000

Dec  3 22:15:11 ECKO kernel: DMAR:[fault reason 05] PTE Write access is not set

Dec  3 22:15:11 ECKO kernel: DRHD: handling fault status reg 3

Dec  3 22:15:11 ECKO kernel: DMAR:[DMA Write] Request device [00:02.0] fault addr b9800000

Dec  3 22:15:11 ECKO kernel: DMAR:[fault reason 05] PTE Write access is not set

Dec  3 22:15:11 ECKO kernel: DRHD: handling fault status reg 3

Dec  3 22:15:11 ECKO kernel: DMAR:[DMA Write] Request device [00:02.0] fault addr b9800000

Dec  3 22:15:11 ECKO kernel: DMAR:[fault reason 05] PTE Write access is not set

```

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## Hum

https://bugzilla.redhat.com/show_bug.cgi?id=538163

Keep an eye on that thread. I'm having the same problems as well

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