pbuffers, extensions to DRM

[Keith Whitwell]

Jon Smirl wrote:
> My current thinking on this is to do it the DRM driver but store the allocation
> data in normal system RAM. This would allow the allocation routines to function
> without touching the framebuffer.
> 
> I would really like to make sure that DRM drivers can function without having to
> map the framebuffer into kernel address space. We only have 1GB of kernel
> address space to work with and the kernel has to live in that 1GB too. 3dlabs is
> shipping a 512MB card now:
> http://www.3dlabs.com/product/wildcatvp/vppro/index.htm and a 1GB model is in
> the works. It is just going to be impossible to map these future cards into the
> kernel.

...

> I've also been poking around a little in the radeon DRM driver. It seems to be
> mapping the framebuffer into kernel space but I never see any place that the
> driver code touches it.

Correct.  There's nowhere the kernel needs to touch the framebuffer.

Keith