I have 2 Pis, a original B+ and a 3. The B+ was used every day as a desktop PC for 4 years with overclocking, so it is pretty worn.So now I use the 3 as a desktop and try to run DOS games in DOSbox on the B+ when I get bored.

I was thinking, is it theoreticaly possibly to hook up my B+ to my 3 and run a script on, say, Raspbian Lite, that would make the B+'s GPU acessable to the GPU of the 3, as some sort of ghetto dual core GPU and pipe all the monitor output of the B+?

Or better yet, is it also possible to hijack all of the GPU and the CPU on the B+ and use it all as a GPU?

If any of this is possable, are there any programs,scripts, or anything avaliable? I am open to any suggestions. Adafruit's SeeSaw, anyone?


I don't think you'd ever be able to get the connection between them fast enough.

Maybe some horrible lash-up over the dsi interface? Make one believe the other is a camera? Yuck.

Given the stock system has its memory, cpu and CPU stacked together with nanometer scale interconnects and doesn't expose a fast bus like a pcie getting one to believe the other was a discrete graphics card is insurmountable. Having the other pi do useful work on its gpu is doable via the opencl stuff but you still are limited by the relatively tight transfer bandwidth on a pi.

  • how about paging data over ethernet? I know that is is not Gigabit, but...I also wonder if a driver could be written to use a group of the GPIO pins as a port and page data on those pins. Is it that those pins couldnt be toggled fast enough? – lockheed silverman Nov 8 '18 at 0:34
  • I think you'd still be up against it. The latency over ethernet will be orders of magnitude slower than the SoC and the bitrate needed to display far exceeds the 'gigabit' capability of the usb hub. You can use SSH to bring a X window from another Pi onto the first one - I can't recall who does the rendering in that situation though? – tobyd Nov 8 '18 at 13:42

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