From: Brian S. Julin <bri@tull.umassp.edu>
  To  : Andreas Beck <becka@rz.uni-duesseldorf.de>
  Date: Mon, 16 Aug 1999 19:51:47 -0400 (EDT)

Re: Ping-pong buffers on KGIcon are here!

On Tue, 17 Aug 1999, Andreas Beck wrote:
> No. The application does not know, what is acceled and what not.

Driver libraries do or should, though.

> > Yes, but the fault only happens when the application tries to
> > access the directbuffer.  If it's doing it through a LibGGI 
> > primitive like it should, the sublib is free to check the 
> > accel_queue_empty GC flag and either sleep or ioctl a flush, 
> > rather than faulting, and in fact the app code can do this as well.
> 
> The app code _must_ do this. On broken HW we must unmap/remap, as we can
> lock the machine otherwise, so there is no choice.

What I'm saying here is primitive-only drawing.  LibGGI would kind
of suck if you had to call Flush between each primitive because some of
them write to the MMAP and some use the accel engine :).

--
Brian