device properties - all it needs is width and height in pixels, stride in
bytes, depth in bits and the framebuffer address.
Features:
- unaccelerated fb console with colours and virtual consoles
- split into console handling and bus frontend
- so far there is only a PCI bus frontend which allows to mmap BARs belonging
to the graphics controller, others should be easy to add.
TODO:
- find an opaque way to change the palette ( probably pass a function
pointer as property ) since this would need to call some firmware interface
which is pretty much always MD
- find a clean way to mmap the framebuffer, just returning the physical
address works on macppc but not on other architectures. Problem is, that
we cannot rely on the address being a bus address - on macppc it is,
but for instance on sparc64 it's not.
