From: Jeff Garzik <jgarzik@pobox.com>
  To  : ggi-develop@eskimo.com
  Date: Thu, 12 Aug 1999 16:09:07 -0400

Re: GGI and XFree86 and stuff

"Jon M. Taylor" wrote:
> 
> On Thu, 12 Aug 1999, Jeff Garzik wrote:
> 
> > Jos Hulzink wrote:
> > > We discussed this before. Trying to see all S3 cards as one big family is
> > > not done, for the chips differ far too much, so it would make the code
> > > unreadable.
> >
> > Not if it is well-written.  I think it can be properly virtualized, and
> > that there is enough common elements to make it worthwhile.
> > ViRGE is
> > not likely be supported; it is already well-supported and also less like
> > other S3 chips.
> 
>         You will not be able to support all the older DACs that the
> pre-Trio chipsets used without producing an XFree86-style monolithic
> driver.  And ViRGE is not much more than a Trio64 with 3D features.

>From looking at my ViRGE GX/2 databook its higher CRTC registers are
sufficiently different enough to discourage me from implementing ViRGE
support at least until Trio and Savage families are working.

With regards to supporting all the DACs, that is indeed a problem.  I am
skirting the issue for now by working on Trio and Savage support first. 
Those are sufficiently similar to be supported with the same base
driver, including RAMDAC code.  Function pointers can be employed to
efficiently handle chip-specific differences, along with judicious use
of static tables.

However, since I have committed to porting the XF86 3.x S3 server to
4.0, I will eventually have to support all those ramdacs in s3lib, if
the XF86 drivers use s3lib.  In that case, the code can easily be shoved
into an optional "s3oldramdac" module.  That implies some duplication of
RAMDAC code, but such is required in order to have the XF86 4.0 driver
be as fully functional as the XF86 3.x driver.

s3lib will need to be modular anyway, so that somebody can build only
Savage3D drivers from the lib if they so desire.


> > I do have a ViRGE card so I was considering playing
> > around with getting 3D GLX going on it.
> 
>         Isn't there some old ViRGE code in Mesa?

If you mean Mesa-CVS/src/S3, that is Windows-specific code, which
requires a proprietary S3 lib.  If there is other 3D S3 code out there I
would love to see it.

	Jeff



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