GDM doesn't start without wanting to start an X Server.

GDM doesn’t start without wanting to start an X Server. But I don’t want to start an X Server, I just want you to be there for my x11vnc + Xvfb…

The problem is - without the proper X11 and dev/fb0, GDM does not start. I do not have a display, and as such, the initialisation for the framebuffer doesn’t occur.

Apparently, they removed the option from GDM to be able to start headless.

I have just bypassed GDM, and loaded SNOME directly on to my Xvfb display.