Messages in this thread | | | From | "D. Hazelton" <> | Subject | Re: OpenGL-based framebuffer concepts | Date | Tue, 23 May 2006 23:38:53 +0000 |
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On Tuesday 23 May 2006 10:11, 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 ?
Agreed. Anything of the sort should be in userspace.
> > framebuffer. There would also need to be a way for userspace to trap > > and emulate or ignore unsupported OpenGL commands. > > That would be most of them for a lot of chips because the hardware can > only do "most" of the work, eg using software fixups after a rendering > command or splitting GL commands into a chain of simpler ones as Mesa > does. All large code.
Putting a full GL stack into the kernel is just plain idiotic. Among the suggestions I made in an initial reply to this was keeping everything possible in userspace adn providing only the minimum necessary stuff in-kernel.
Doing otherwise - providing full emulation for unsupported commands or features - is just copying the mistakes made by M$ with DirectX.
> > effort. Given that sort of support, a rootless xserver would be a > > fairly trivial wrapper over whatever underlying implementation there > > was. > > You mean move the X server from being root (privileged) to kernel (even > more privileged) and pray there are no bugs in it ? > > Bits of the model are right - look at DRI for some (perhaps not pretty) > evidence of that. Clearly the kernel needs to control the GPU, DMA and > access to buffers. It isn't clear anything higher level belongs anywhere > but user space.
Exactly what I suggested on seeing the original post.
I am currently looking for some information or help in making the Framebuffer devices use DRM and setting up a userspace system that interfaces with the DRM backed framebuffer device to provide full 2D and 3D acceleration of all supported features and *userspace* emulation of the unsupported stuff.
Mesa is a good place to start for the 3D stuff, and either XAA or one of the numerous 2D graphics packages would be a place to start for the 2D acceleration.
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