Subject: Re: Alpha X server limitations
To: Ben Tober <tober@bbnplanet.COM>
From: Chris G. Demetriou <>
List: port-alpha
Date: 01/28/1997 15:26:31
> Hmm, this could be the wrong impression, but I believe that console
> interfaces (in the context of X) usually just deal with the keyboard and
> possibly the mouse but usually not the framebuffer.  I thought that
> framebuffers were generally mmap()'d into the address space of the X server.


"How do you find out what there is to map, and how do you map it?"

In what i'd call a sane world, you open a device, say, /dev/ttyE0
which corresponds to the frame buffer device, ask it what it is, how
much of it can be mapped, and then mmap it using that device.

As far as I can tell, Xfree86 on the alpha and x86 wants to do
something like the following for PCI frame buffers:

	(1) grovel around PCI configuration space to see what
	    frame buffer devices exist in the machine,

	(2) groven around PCI configuration space some more
	    to see where they're mapped into the system address

	(3) map that with /dev/mem.

That'd be equivalent to encoding information about what TC slots were
where in the TC Alphas, then looking in those slots' ROMs to find an
ID that is known to be a TC video board, etc.