startx vanity

[Bruce M Simpson]

On Wed, Apr 16, 2003 at 08:06:02PM +0100, Ian Morrison wrote:
> > What graphics chipset are you using? This is just par for the course.
> It's an s3 savage in my Thinkpad T22..

I get exactly the same behaviour, in fact if you look closely, you'll notice
that the artifact is the IBM ThinkPad BIOS logo.

(I have exactly the same machine.)

> Isn't it possible to have just exec a program that takes charge, forks a
> rest of the stuff in the background, then fades and execs xclock or
> somthing?  i really need to work out in my head what x is doing..  any
> ideas for free dox online?

The visual artifacts you're seeing are caused by the state of the video
memory (and SVGA registers), before XFree86 performs its initialization.

It would be possible to write an XFree86 module which tries to perform
a 'fade in' as you describe. A chipset specific hack wouldn't really
be desirable for this and would be difficult to maintain.  However such
a module has to take into account the pixel formats used at the desired
screen depth so it knows *how* to clear the memory before it's displayed.

As to understanding what XFree86 is doing to your machine, reading
/var/log/XFree86.0.log and following, line by line, what it does, may be
helpful - although a familiarity with BIOS, PCI, and PC architecture in
general is really needed.

It might be as simple as clearing the memory, fencing off memory accesses
to let the caches catch up (post-MTRR register setup), and then doing a
bottom-of-frame wait. (All of which was much easier to do on the Amiga...)

I fear this is going OT. Would anybody be interested in such a hack? 

BMS