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Hello,

>> XFree's cgsix driver ( suncg6 ) is unaccelerated but usable, at least
>> it uses the hardware cursor. Adding acceleration shouldn't be too hard
>> though, there are other, sufficiently simple drivers one could use as
>> examples and then there's Xsun.
>
> Maybe we should think about how mmap function should be implemented.
> If we will introduce a "new" WSDISPLAYIO_GINFO ioctl, we should not
> have WSDISPLAYIO_MODE_DUMBFB and maybe the new ioctl should provide
> an offset value to be used to mmap framebuffer memory.
> (In cgsix case, CGSIX_RAM_OFFSET should be returned)
I agree, the Xserver shouldn't have to meddle with PCI BARs, at least 
not to access the framebuffer. On the other hand the drivers I've seen 
so far map the framebuffer when you mmap() offsets between 0 and 
aperture_size.
As far as I can tell XFree's SBus code uses /dev/fb to talk to the 
hardware.

> I wonder how we should also provide mmap offsets of device dependent
> registers for acceleration, though.
Agreed again, but it would be a bit more complicated - some PCI 
framebuffers use more than one BAR for registers, then there's this 
nonsense with hard-wired VGA registers and so on, some need access to 
PCI IO space which is different on x86 and almost everything else - for 
kernel code that's not a problem thanks to bus_space_* but userland 
code can't use it.
Hmm, newer cards seem to use mainly memory-mapped registers but I'm not 
sure we can rely on that.

have fun
Michael
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