On Wed, Jan 21, 2015 at 10:35:58AM +0100, Daniel Vetter wrote: > On Tue, Jan 20, 2015 at 05:21:42PM +0000, David Woodhouse wrote: > > Commit 82460d972 ("drm/i915: Rework ppgtt init to no require an aliasing > > ppgtt") introduced a regression on Broadwell, triggering the following > > IOMMU fault at startup: > > > > vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem > > dmar: DRHD: handling fault status reg 2 > > dmar: DMAR:[DMA Write] Request device [00:02.0] fault addr 880000 > > DMAR:[fault reason 23] Unknown > > fbcon: inteldrmfb (fb0) is primary device > > > > Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > I sugggested this change to David after staring at the offending patch for > a while. I have no idea and theory whatsoever why this would upset the gpu > less than the other way round. But it seems to work. David promised to > chase hw people a bit more to get a more meaningful answer. The issue is likely the execution of the golden render state batch concurrently with the flip over to ppgtt. The GPU throws a pagefault and we get an ERROR reported. http://patchwork.freedesktop.org/patch/38270/ http://patchwork.freedesktop.org/patch/38269/ -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx