(thanks ryoon for a hint) To boot it with graphical acceleration on uefiboot, I need to disable genfb specifically. That is, drop to boot prompt, type > userconf disable genfb > boot
you can add this to /boot.cfg too. Otherwise it tries genfb for the nvidia card, and i915 for intel, which doesn't work well because they are physically dependent cards, and I get a blank screen after mode switch. Another option is to disable i915drmkms, then I am left with the nvidia genfb.
