Completely disable video output?

[Scott Newell]

I'd like to disable video output completely. What's the easiest way to do that?

I've tried switching to a serial terminal on ttyS2, but I don't see 
any grub output over serial and I still get grub over video. (I do 
get serial activity once the kernel starts, so I know the serial port is ok.)

Hardware is a Fitlet2 embedded PC, connected to a 4k TV over HDMI. 
(The 4k is the problem--I want to force it to 1920x1080, and I can't 
seem to find a way to do that in grub, either.)

thanks!
newell