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> The GPU is decent for a phone, if all you're doing is 2D/video stuff.

The lack of CPU power wouldn't be such a big issue, since the real computing power of the Pi is in the GPU anyways, except that you can't actually do anything else with the GPU, because you need to use Broadcom's driver blob.

As a side note, I think it's pretty disappointing to have an "educational", "open" computer that blocks you from actually using all the hardware.

[1]: http://www.raspberrypi.org/archives/2221#comment-34981




It is a bit disappointing, but they have taken the pragmatic view, that it is better to have what they have delivered than nothing at all.

I would really like to see what the full capabilities of the chip are. The GPU seems to implement almost the full GLES driver itself. As I recall, it iss compiling the shaders GPU side. That's some considerable general purpose computing hidden behind the wall.


There are two major programmable parts to the GPU - the Videocore CPU (VPU) and the shader processors (QPU).

The VPU is dual core with a 16 way SIMD integer unit with a 64x64 byte vector register file, and 32 register 32 bit scalar register file. Its accessible now, for instance see: https://github.com/hermanhermitage/videocoreiv/wiki/VideoCor...

There are a few people targeting compilers and assemblers at the VPU. I think vbcc will probably come first, but I'm aware of people hacking on gcc and llvm.

I generate all assembly from emit() calls in C, but I may publish a better assembler soon.

The QPU work is not so advanced, but we actually have had a handle on the QPU instruction format for a while now, but we need more hands on deck to expose it in the open. There is also a challenge of hooking into the blob and dispatching QPU fragments. I would hope we have something working by the Q3.

See https://github.com/hermanhermitage/videocoreiv/wiki/VideoCor... for some preliminary background.

The QPU instructions have 3 VLIW style slots - <fp-add; fp-mul; signal>. I'll push a qpu.arch when I get some time back on the raspberrypi.




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