Not sure if my many crashes with the Armbian Ubuntu image are due to the governer issues many others are reporting, but I suspect so. I merged these instructions for setting up uboot for Ubuntu with these ones for fixing a handmade image, and came up with this list of uboot instructions:
As for me, I never had been able to fix the crashing issue even though I disabled the governor service. I switched to Archlinux and it’s runs pretty solid without crashes (except when playing with GPIO’s). The GPIO’s are a bit problematic though. Most of the pins are not usable.