The hunt for 3D graphics access from homebrew/Linux ("Other OS") on the PS3 has finally paid off. Glaurung with the help of IronPeter and others have now released a draft [Register or Login to view links] along with the [Register or Login to view links].
To quote: The contexts are truely independent including:
- object bindings: since lv1_gpu_context_attribute:fb_setup fails with LV1_BUSY, we have to bind objects by hand in the newly created context. For this we can use the exact same commands FB_SETUP puts in the FIFO ([Register or Login to view links]) when creating the first context.
- iomapping: the lv1_gpu_context_iomap call has to be done again to allow the GPU to access XDR. The location of the mapping in GPU space (GPU_IOIF) can be the same or different from the value used by ps3fb (0x0d000000)
- FIFO control and location: the FIFO control registers initially read as zero. They can be written to with the address of the second context FIFO. In my test I used the 64kB just before the ps3fb FIFO (i.e. 128kb from the end of the XDR ps3fb_videomemory region). So I put 0x0e1e0000 in the registers (0x10000 less than the value I read in ps3fb context), yet we still have to figure out how this value is obtained from the address of the ps3fb_videomemory, so that we can locate the FIFO anywhere we want.
I've finally been able to setup and use a second independent context. I was able to perform the 'upper VRAM workaround' from this second context, even though the first context (setup by ps3fb) has restricted upper VRAM access through DMA (by means of the lv1_gpu_memory_allocate(ps3fb_videomemory.size,... ) call).
This means interesting things:
- We don't need the FIFO workaround anymore! But the 'upper VRAM' one is still needed and can be executed from second context.
- We should finally be able to provide one (or several) independent kernel module for all our GPU work (3D,Xorg,VRAM mtd). I'll look into this tomorrow and try to provide this module.
- We should be able to have both 3D and accelerated Xorg working at the same time.
It is not yet finished, and mostly untested, but it shows my plan for the interface with userspace.