genfb —
generic framebuffer console driver
genfb* at pci?
genfb* at sbus?
genfb* at intvid? (mac68k)
genfb* at macvid? (mac68k)
wsdisplay* at genfb?
The genfb driver provides support for generic
  framebuffers that have no native driver. All it needs are some parameters to
  describe the framebuffer and an address.
When attaching to a pci(4) bus the
  driver is configured via device properties:
  - width(- uint32)
- Width in pixels.
- height(- uint32)
- Height in pixels.
- stride(- uint32)
- Line size in bytes.
- depth(- uint32)
- Bits per pixel.
- is_console(- bool)
- If true, genfbwill try to become the system
      console.
- address(- uint32)
- Bus address of the framebuffer.
When attaching to sbus(4) all those
  parameters are retrieved from the firmware.
All those parameters are configured with Mac OS, and retrieved from the boot
  loader.
There is no way to change the color map even when the firmware supports it. The
  pci(4) bus frontend has only been
  tested on macppc, i386, and amd64 and requires machine dependent code to pass
  the properties mentioned above. So far only macppc, i386, and amd64 provides
  them.