Sorry for the late reply on this. > Could you try adding the following kernel parameters (via Grub > by > pressing 'e', then appending the option at the end of the > cmdline): > > * nomodeset > > and if it doesn't work: > > * amd_iommu=pt ivrs_ioapic[32]=00:14.0 iommu=soft The amd option didn't work, but nomodeset allowed me to get to a shell, at which point I could start experimenting with various settings to see if I could get a graphical environment. I finally did by switching over to the proprietary kernel (which points to a graphical driver issue with AMD Navi cards in the libre kernel), but that's obviously less than ideal. Still, it means I can finally start using the system in earnest. Thanks for all your help!