This is a `virtual' frame buffer device. It operates on a chunk of
unswappable kernel memory instead of on the memory of a graphics
board. This means you cannot see any output sent to this frame
buffer device, while it does consume precious memory. The main use
of this frame buffer device is testing and debugging the frame
buffer subsystem. Do NOT enable it for normal systems! To protect
the innocent, it has to be enabled explicitly at boot time using the
kernel option `video=vfb:'.

To compile this driver as a module, choose M here: the
module will be called vfb. In order to load it, you must use
the vfb_enable=1 option.

If unsure, say N.

source code:

drivers/video/vfb.c