This is a monster patch that required changing a whole bunch of things.
There are performance and stability issues all over the place, but it works.
Pretty cool, I have to admit :^)
Maybe there will be other types of physical ranges to map in the future.
This API doesn't seem at all specific to framebuffers.
Also tidy up a bit in BochsVGADevice.
Currently you can only mmap the entire framebuffer.
Using this when starting up the WindowServer gets us yet another step
closer towards it moving into userspace. :^)
Use the BochsVGA card's virtual-height + virtual-y features to implement
a "hardware double buffering" type scheme.
This is a performance degradation since we now draw a bunch more than before.
But there's also no tearing or cursor flickering. I'm gonna commit this and
try to improve upon it. :^)
Instead of cowboy-calling the VESA BIOS in the bootloader, find the emulator
VGA adapter by scanning the PCI bus. Then set up the desired video mode by
sending device commands.
