01kris

I also had this exact same issue with the asrock rack romed8-2t board, with an arc A310 gpu. Initially only the aspeed ipmi graphics adapter was visible under /dev/dri, even though lspci would show the card, and I could even select it for gpu passthrough to a vm. I eventually was able to solve it by changing the 'Primary Graphic Adapter' in the bios to 'Onboard' (Advanced -> Chipset). I did not need to blacklist the ast module; once i made that change in the bios and rebooted, I still had full ipmi kvm functionality, and the arc gpu showed up under /dev/dri -- intel_gpu_top also works.

I just ran into this same issue. For me the solution with the ROMED8-2T board, was through the bios. Advanced -> Chipset and change primary graphic adapter to 'Onboard'.