3D stack = mesa + drivers if any
graphics stack = 2D + 3D stacks and driver support if any
OpenGL stack = mesa + drivers if any
That was the original point I was trying to make that Haiku has recent mesa support but no drivers other than software. But that doesn't mean that adding the accelerated driver is porting an entire new stack merely enhancing it with hardware support the stack is there regardless of the accelerated driver. In factsumy opengl stack is more complete when running without the r600 driver as it only supports GL2 and not 2.1 as mesa software does but there really isn't any speed comparison yet.
Another thing that would be cool is getting llvmpipe running at full speed on haiku from what I understood it was working about the same speed pack in Nov/Dec '09 but apparently it has made futher progress on Linux
So is Haiku basically missing the drm ? I imagine most of the userspace driver should port easily.
Thats how I understand it... you should contact Artur 'aljen' Wyszynski to be certain though. you should be able to contact him on the haiku mailing list. I think he had also been attepting to build the intel gallium drivers... I'm not sure how far he got.