Direct SPU to SPU DMA requests on the Cell Processor?

Question

Normal DMA requests on the Cell happen between the SPUs and the PPU. However, I have read that it is possible to set up DMA directly between SPUs. Anyone have any idea how this is accomplished?

Answer 1

Have a look at spe_get_ls(). This will help you to setup a list of effective addresses that you can use to transfer data between local stores. You may need some management to map spe identifiers to physical SPUs.

Answer 2

The trick is essentially what Chris said. The local store of one SPE is memory-mapped into the PPE's memory space. And then you just perform a regular DMA transfer from the other SPE to that address on the PPE.

I'm sorry I don't have the exact code for this. It's been a year or so since I had to do any of this. :)