From what I can tell the Intel kext requires the Intel Management Controller, but on Mojave I have had no issues. I would like to attempt to upgrade Mac OS X to Big Sur but I am not sure if there would be graphical glitches. I tried Catalina before but It had a few visual glitches. I would like to not loose my current install. My Specs: Lenovo Thinkpad T430 Running coreboot/seabios, Intel HD Graphics 4000, i3-3210M, and 1600x900 display.