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    SubjectRe: OpenGL-based framebuffer concepts
    On Tuesday 23 May 2006 10:28, Jeff Garzik wrote:
    > Alan Cox wrote:
    > > On Maw, 2006-05-23 at 01:08 -0400, Kyle Moffett wrote:
    > >> generation graphics system, I'd be interested in ideas on a new or
    > >> modified /dev/fbX device that offers native OpenGL rendering
    > >> support. Someone once mentioned OpenGL ES as a possibility as it
    > >
    > > So for a low end video card you want to put a full software opengl es
    > > stack into the kernel including the rendering loops which tend to be
    > > large and slow, or dynamically generated code ?
    > Indeed, consider the extent of that phrase "dynamically generated code."
    > To do modern OpenGL (mostly fragment and vertex shaders), you basically
    > must have a compiler front-end (C-like language), a code generator (JIT)
    > backend for your architecture (x86, x86-64, ...), and a code generator
    > backend for your GPU.
    > Further, as Keith Whitwell and others have rightly pointed out, a modern
    > GPU needs such advanced resource management that the X server (or
    > whatever driver) essentially becomes a _multi-tasking scheduler_.
    > Consider the case of two resource-hungry 3D processes rendering to the
    > same X11 screen, and you'll see why a GPU scheduler is needed.
    > Modern graphics is highly aligned with the Cell processor programming
    > model: shipping specialized binary code elsewhere, to be remotely
    > executed.
    > OTOH, I think a perfect video driver would be in kernel space, and do
    > * delivery of GPU commands from userspace to hardware, hopefully via
    > zero-copy DMA. For older cards without a true instruction set, "GPU
    > commands" simply means userspace prepares hardware register
    > read/write/test commands, and blasts the sequence to hardware at the
    > appropriate moment (a la S3 Savage's BCI).
    > * delivery of bytecode commands (faux GPU commands) from userspace to
    > kernel to hardware. Much like today's ioctls, but much more efficient
    > delivery. Used for mode switching commands, basic monitor management
    > commands, and other not-vendor-specific operations that belong in the
    > kernel.
    > * interrupt and DMA handling
    > * multi-context, multi-thread GPU resource scheduler (2D/3D context
    > switching is lumped in here too)
    > * suspend and resume
    > and nothing else.

    Thanks for this list. Looks like if I'm going to do any code writing it won't
    be solo, because a lot of this stuff - mostly the scheduler and interrupt
    handling - is way over my head. (However, I will try to learn and will be
    doing even more research when I get to the point where this is needed to be

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