MMIO access [was Hardware cursor]

[James Simmons]

> > With cards framebuffers growing in memory size 
> Who says you need to map it all ?

Well most low end cards don't have have OpenGL on chip so you need access
to the framebuffer between accel operations.

I realized over the weekend what the linux kernel really needs. This is
something I'm going to purpose to the MM group. Not just framebuffer and
accel engine access issues exist. Linux doesn't have any way to
handle two process on a SMP machine accessing a shared MMIO region. This
could cause other cards to lock up if you have  two process programming
the card at the same time. So I'm in process of writing the schedular to
have to ability to prevent processes to simulatenously access any MMIO
region.