This is likely of no use to anyone but me, ever, but I’ll post it anyway. I’m trying to install Linux on a 10-year old Beckhoff CX5020 industrial computer, and everything works fine until about somewhere in the middle of the user-mode startup process when the screen goes blank and never comes back. I tried disabling X and that didn’t matter. Even booting in single-user mode didn’t help. It still went blank while booting. I could SSH in over the network to debug, but couldn’t get a working monitor.

The problem seems to be the Kernel’s video driver mis-understanding the number and/or type of video ports that the CX5020 has. The solution is easy: add the video=LVDS-1:d option to the kernel’s command line. After that everything seems to work fine. It boots up and runs X as well as could be expected for a 10 year old compact PC. Which is to say not tremendously quickly.