[forum] How about running X on top of something else?

[Jos Hulzink <josh@stack.nl>]

Once upon a time, Sven Luther wrote:
>On Thu, Mar 27, 2003 at 12:21:58AM +0100, Christoph Egger wrote:
>> > > Bah.  We don't relocate resources unless we need to.  So that ball's as
>> > > much in your court as it is in ours.
>> > 
>> > Any X reassignment of PCI resources is unsafe in Linux 2.4, and going to
>> > get more so. The DGA comemnt applies here the other way around - you 
don't
>> > currently have a way to get the kernel to do the work for you. We need to
>> > address that. X doesn't know enough hw issues or locking
>> 
>> That's the point where KGI comes into the place. Most of you, I guess,
>> remember
>> on the heating discussion on the linux kernel ml in 1997/1998.
>> 
>> In the meantime, it has been redesigned and rewritten from scratch. So, all
>> what you (still) believe to know about KGI is very likely out of date.
>> 
>> KGI is splitted in two parts. The kernel driver knows all stuff to access
>
>I still don't understand why you simply did not use the fbdev framework
>for this ? This is i believe one of the reasons GGI failed, because it
>tried to redesign everything, without taking into account any of the
>stuff that pre-existed at that time.

First of all: you should see GGI and KGI seperately now. If you are going to 
use GGI, you'll be able to run X on anything you like, even on KGI, the 
driver system we're talking about. But, if you adopt GGI, KGI is no must at 
all.

To answer your question:

Fbdev was never ment to do accelleration in the first place. Fbdev drivers are 
not portable. When you really think about using the fbdev drivers as bottom 
layer of X, you'll get a X server that has very OS and driver specific 
features, for the fbdev driver is only available at Linux, and hacked into 
FreeBSD. As long as there is no cross platform driver, you will be unable to 
say: Just use this driver, and you'll have a full featured X system.

KGI was designed for portability. At the moment we're just talking linux and 
*BSD, but there is more. Just an example: The Matrox KGI driver set up a 
stable video mode in Windows 2000 once, with basic 2D accelleration. The 
needed code was written in two days. Unfortunately, that code is propriety, 
and KGI is not allowed to use it.

KGI has a simple thought in mind that we only see back at the X drivers and 
some commercial stuff: A driver must be able to run on any platform, with 
only a recompile.

Besides, fbdev was yet to be invented when GGI was started. Linus just didn't 
like the idea of graphic drivers in a kernel, and our project team was so 
small that we were unable to get our project goals clear.

Best regards,

Jos Hulzink