[Intel-gfx] "BUG: unable to handle kernel NULL pointer dereference at 0000000000000070" in [i915] reset_common_ring

[Bjørn Mork]

Bjørn Mork <bjorn at mork.no> writes:
> Chris Wilson <chris at chris-wilson.co.uk> writes:
>
>> and at a guess
>> intel_iommu=igfx_off to avoid the hangs in the first place.
>
> Thanks for the tip. I'll try that

My memory is more than a bit flakey, but this did eventually ring a
bell.,.  And googling I see that I have tried that tip before without
success:

 https://bugs.freedesktop.org/show_bug.cgi?id=101288


If you look at the logs attached to that bug, you'll see that the PC was
running with "intel_iommu=igfx_off" at the time of the hang:

 [ 54047.182] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.9.0-3-amd64 root=UUID=71507198-90f4-4c25-be41-efc47d2dedd1 ro intel_iommu=igfx_off


I believe the GPU hang reported in that bug is the same?  The driver
just did not Oops while trying to reset.


Bjørn