On 04/02/17 03:40, Mick wrote: > On Friday 03 Feb 2017 09:03:10 Peter Humphrey wrote: >> On Thursday 02 Feb 2017 05:12:17 Dale wrote: >>> Peter Humphrey wrote: >>>> Hello list, >>>> >>>> I was looking through dmesg this morning and found 1231 instances (!) of >>>> this error: >>>> >>>> DMAR: DMAR:[DMA Read] Request device [01:00.0] fault addr f400156000 >>>> DMAR: [fault reason 06] PTE Read access is not set >>>> >>>> This is an Intel i7 box with an NVMe SSD and an AMD/ATI Amethyst XT >>>> Radeon R9 M295X display card. The kernel is gentoo-sources-4.4.39. I've >>>> tried setting intel_iommu=on or =pt as kernel parameter to no effect. I >>>> don't want to set it =off because I've read that it slows the machine >>>> dramatically. >>>> >>>> Googling has shown nothing, other than playing with that kernel >>>> parameter. Does anyone here know what the problem is? >>> >>> I'm not sure if it applies but I found this: >>> >>> https://forums.gentoo.org/viewtopic-p-7904584.html#7904584 >>> >>> It should scroll down a bit to the post. The last comment seems to have >>> a solution. >>> >>> Hope that helps. If not, maybe someone else has a better idea. >> >> Thanks, but no, it makes no difference here. > > Peter, I recall a similar problem shown in the logs of an i7. and all I did > was to enable IOMMU in the kernel, just as a message in the logs recommended. > > From memory I built in the kernel something like > CONFIG_INTEL_IOMMU_DEFAULT_ON > as well as some Intel related IOMMU options. I did not pass any options on > the > kernel line at boot time. The error messages stopped as a result. >
This my kernel args for a MS surface 4 - acpi_osi=Linux i915.semaphores=1 intel_iommu=off pcie_port_pm=off stops it. BillK
