4 ms·

So what exactly were the Magic Leap cores? They don't look like the GPU or CPU cores...

spuz 3y ago
The specs of the Magic Leap 2 say "14 core computer vision processing engine (CVIP)" which matches the 14 cores shown in the photos.
jsnell 3y ago
The original source[0] speculates they're computer vision DSPs, specifically Tensilica Vision DSPs from Cadence. [0] https://www.youtube.com/watch?v=ERm1StY-4uY https://www.youtube.com/watch?v=ERm1StY-4uY
- jsheard 3y ago
  It wouldn't be the first time AMD has bundled some Cadence DSP cores into their designs, they used them for TrueAudio back in the day as well.
  - dfox 3y ago
    Intel also integrates Tensillica cores as sound DSP (IIRC into PCH not CPU itself). And NXP has some kind of i.MX part that somewhat closely couples Tensillica DSP core(s) to ARM SoC. So I would say that today probably everybody except TI uses Cadence/Tensillica DSP cores.
    - kjs3 3y ago
      I don't think Analog Devices uses Tensillica, and I think NXP still has things in the 56300 derived line shipping, but Tensillica does seem to have soaked up the lions share of DSP functionality these days.
      - dfox 3y ago
        I meant as an DSP core inside some larger chip, not as free standing DSP. It does not make much sense to design a chip that just contains a Tensillica core and nothing else because you lose all of the customizability and the market for such a thing probably is not big enough to offset the NRE and licensing costs (obviously, with Espressif stuff being the exception, but the RF part in there is pretty significant part of the design).
        kjs3 3y ago
        That's a fair clarification. The 56000 had a tiny number of SoC-like build-ins (with a 68000), but I don't think they've been sold in decades.
Red_Leaves_Flyy 3y ago
And a follow on question… could they be turned on and used?
- jsheard 3y ago
  Probably not, these modular bits of silicon are usually tied to eFuses that are blown at the factory to irrevocably disable them in SKUs that aren't supposed to have them. Many years ago it was sometimes possible to re-enable disabled cores by poking the right registers, but manufacturers learned their lesson and now they make sure that silicon stays dead. Besides, even if you could enable these DSP cores you'd be hard pressed to do anything useful with them, I don't believe there's any public documentation or tooling whatsoever for Cadence DSPs.
  - fulafel 3y ago
    How do eFuses work to ensure it's physically irrevocable?
    - fragmede 3y ago
      eg if the fuse blows the line that powers up that part of the chip, then it simply can't power up after the fuse has been blown and thus is unusable. Going in and fixing that blown trace inside of an IC is beyond the capabilities of almost everyone because decapping a chip renders it inoperable.
      - fulafel 3y ago
        I think decapping doesn't necessarily render the chip inoperable, there's some research around attacking tamper resistant hardware and probing the decapped chips while powered on. But you have to be more careful about it of course. Also do all techniques require decapping? Seems in principle you could navigate by x-ray and fix traces disconnected by electromigration efuses using ion beam/implantation, possibly through the packaging. edit: here's someone talking about running decapped chips. https://electronics.stackexchange.com/a/400899 https://electronics.stackexchange.com/a/400899

spuz 3y ago

The specs of the Magic Leap 2 say "14 core computer vision processing engine (CVIP)" which matches the 14 cores shown in the photos.

jsnell 3y ago

The original source[0] speculates they're computer vision DSPs, specifically Tensilica Vision DSPs from Cadence. [0] https://www.youtube.com/watch?v=ERm1StY-4uY https://www.youtube.com/watch?v=ERm1StY-4uY

jsheard 3y ago
It wouldn't be the first time AMD has bundled some Cadence DSP cores into their designs, they used them for TrueAudio back in the day as well.
- dfox 3y ago
  Intel also integrates Tensillica cores as sound DSP (IIRC into PCH not CPU itself). And NXP has some kind of i.MX part that somewhat closely couples Tensillica DSP core(s) to ARM SoC. So I would say that today probably everybody except TI uses Cadence/Tensillica DSP cores.
  - kjs3 3y ago
    I don't think Analog Devices uses Tensillica, and I think NXP still has things in the 56300 derived line shipping, but Tensillica does seem to have soaked up the lions share of DSP functionality these days.
    - dfox 3y ago
      I meant as an DSP core inside some larger chip, not as free standing DSP. It does not make much sense to design a chip that just contains a Tensillica core and nothing else because you lose all of the customizability and the market for such a thing probably is not big enough to offset the NRE and licensing costs (obviously, with Espressif stuff being the exception, but the RF part in there is pretty significant part of the design).
      - kjs3 3y ago
        That's a fair clarification. The 56000 had a tiny number of SoC-like build-ins (with a 68000), but I don't think they've been sold in decades.

Red_Leaves_Flyy 3y ago

And a follow on question… could they be turned on and used?

jsheard 3y ago
Probably not, these modular bits of silicon are usually tied to eFuses that are blown at the factory to irrevocably disable them in SKUs that aren't supposed to have them. Many years ago it was sometimes possible to re-enable disabled cores by poking the right registers, but manufacturers learned their lesson and now they make sure that silicon stays dead. Besides, even if you could enable these DSP cores you'd be hard pressed to do anything useful with them, I don't believe there's any public documentation or tooling whatsoever for Cadence DSPs.
- fulafel 3y ago
  How do eFuses work to ensure it's physically irrevocable?
  - fragmede 3y ago
    eg if the fuse blows the line that powers up that part of the chip, then it simply can't power up after the fuse has been blown and thus is unusable. Going in and fixing that blown trace inside of an IC is beyond the capabilities of almost everyone because decapping a chip renders it inoperable.
    - fulafel 3y ago
      I think decapping doesn't necessarily render the chip inoperable, there's some research around attacking tamper resistant hardware and probing the decapped chips while powered on. But you have to be more careful about it of course. Also do all techniques require decapping? Seems in principle you could navigate by x-ray and fix traces disconnected by electromigration efuses using ion beam/implantation, possibly through the packaging. edit: here's someone talking about running decapped chips. https://electronics.stackexchange.com/a/400899 https://electronics.stackexchange.com/a/400899