Quoting Joerg Roedel (2019-01-22 18:51:35) > On Tue, Jan 22, 2019 at 04:48:26PM +0200, Joonas Lahtinen wrote: > > According to our IOMMU folks there exists some desire to be able to assign > > the iGFX device aka have intel_iommu=on instead of intel_iommu=igfx_off > > due to how the devices might be grouped in IOMMU groups. Even when you > > would not be using the iGFX device. > > You can force the igfx device into a SI domain, or does that also > trigger the iommu issues on the chipset? To be honest, we've had a mixture different issues on different SKUs that have not been hit in the past when intel_iommu was just disabled by default. I know that in one group of the problems, the issue has been debugged into the GPU having its own set of virtualization mapping translation hardware with caching and it fails to track changes to the mapping. So if a identity mapping was established and never changed, I'd assume that to fix at least that class of problems. Would just passing intel_iommu=on already cause a non-identity mapping to possibly be used for the integrated GPU? If it did, then it would explain quite few of the issues. We have many reports where just having intel_iommu=on (and using the system normally, without any virtualization stuff going on) will cause unexplained GPU hangs. For those users, simply switching to intel_iommu=igfx_off solves the problems, and the debug often ends there. Regards, Joonas > In any case, if iommu=on breaks these systems I want to make them work > again with opt-out, even at the cost of breaking assignability. > > Regards, > > Joerg _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
