That's the function of the OS glue, deep down in bsd_video.c and friends
that Simon is working on.

Andrew

----- Original Message -----
From: "Todd Vierling" <tv@wasabisystems.com>
To: "Simon Burge" <simonb@wasabisystems.com>
Cc: "NetBSD-current Discussion List" <current-users@netbsd.org>
Sent: Friday, July 20, 2001 12:53 PM
Subject: Re: Why not track our xsrc with X11R6.6 from X.org?

[snip]
> 1. determine the mmap-allowable data area of a card
> 2. arbitrate writes to control registers
> 3. validate DMA values used in control registers before an actual write to
>    those registers is performed
>
> This shouldn't be a difficult thing, but it would likely require that
XFree
> supply some level of abstraction to make (2) and (3) work -- because the
> hardware vendor needs to write the code for (2) which will call our
supplied
> hooks for (3).