xserver on OpenGL

[Keith Whitwell]

Keith Packard wrote:
> Around 9 o'clock on Dec 8, Allen Akin wrote:
> 
> 
>>Just to elaborate some of these points:  PBuffers have a "format" system
>>completely separate from Visuals (so that you can render to undisplayable
>>targets, like high-dynamic-range images or depth buffers for shadow maps).
>>Making this work usually requires rethinking memory allocation and going
>>well beyond what the X server would require on its own.
> 
> 
> Yes, just like Render has Picture Formats that are separate from visuals 
> (and can include Alpha information not present in visuals).  I expect 
> pbuffers require even more information.
> 
> I would have thought that the memory allocation problem was already solved 
> though; pbuffers look a lot like textures to me.   One thing that kdrive 
> does is allow inactive objects to be pushed out of video memory; that permits 
> some auto-tuning of the working set in the graphics card and also allows 
> for compaction of the space (kicking things out and later reallocating 
> them).
> 
> Given the large number of pbuffers that the X server is likely to use, I'd 
> like to know if we could place them in AGP memory as well.  Not all 
> machines have 256 meg video cards...

This will depend entirely on the hardware.  For many cards, the answer is yes.

Keith