Patch adding supoort for X Double Buffer extension

[Samuel Rydh]

On Sun, Apr 11, 2004 at 07:51:38PM +0000, winden NTW wrote:
> 
> I'm attaching a patch I did today, please consider adding it for testing 
> purposes.
> 

Thanks... but why would one want to double buffer the entire framebuffer?

MOL tries very hard to refresh only portions of the display that has changed
(by utilizing the MMU and by checksumming) in order to reduce the amount of
data that has to go through the AGP bus. As far as I can see, asking X to
double buffer will (dramatically) increase the amount of data which
has to be shuffled. A quick test on my machine shows that this is indeed
what happens.

As far as I can see, the only possibility to radically speed up the X11
video driver is using offscreen VRAM for the framebuffer. Unfortunately,
no good API exists for this (at least I haven't found it).

/Samuel