From: Andreas Beck <becka@rz.uni-duesseldorf.de>
  To  : ggi-develop@eskimo.com
  Date: Thu, 5 Aug 1999 20:51:39 +0200

Re: GL, X, accel and ggi

> Plus this driver is needed to properly virtualize the accel engine 
> to each process. 

Great. They finally bought this ...

> open say 3 OpenGL programs in X then each window open will open /dev/gfx
> with that window area. With this driver when you mmap say the Z buffer for
> window one than only the area of the window is mmapped. 

This is hard on most platforms, as paging granularity is in the way. But
better than nothing. A real good solution is only possible with hardware
designed for that.

> Most noteably how to handle the accels registers. They are
> the tricky part. Any ideas here?

I can offer advice here. Basically there are two possible solutions:

1. Direct mapping and a save/restore mechanism for context switching.

2. Streamed access using something like the PingPong buffers discussed here
again recently. This design helps, if 1. is not feasible, as e.g. the card
state cannot be completely restored/saved.

More in PM. Just ask. I have put much thought into that in the past.

CU, Andy

-- 
= Andreas Beck                    |  Email :  <andreas.beck@ggi-project.org> =