Question Can someone post a photo of Efuses?

Discussion in 'Switch - Hacking & Homebrew' started by Enryx25, Aug 31, 2017.

  1. Supercool330

    Supercool330 GBAtemp Advanced Fan

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    This is an excellent point, the material these components are made out of aren't designed to melt. Thinking of them like you would think of the macro level circuitry we work with doesn't really make any sense.

    Again, this point is spot on. The efuse isn't burned, it has its resistance increase through electromigration.

    Probably not. Anything you would do to bypass the eFuses would almost certainly destroy the rest of the IC.

    Possibly, but a lot of these exploits are due to design flaws in the IC. Modern chips tend to have much better eFuse design, where it may be possible to bypass, but it is becoming less likely.

    Another thing that is important to remember is that many computer components are actually orders of magnitude smaller than this, and they all work just fine (plus or minus some weird quantum effects that screw things up sometimes). When things get this small, a lot of the stuff that makes sense at the macro level falls apart.
     
    Last edited by Supercool330, Sep 13, 2017
  2. Dinzy

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    I am not familiar with where these things are on this chip, but the article below shows Intel and TSMC were using efuses at M1. Drilling down to M1 is ridiculous. It would almost make more sense to drill in from the transistor side for any ridiculous hypothetical repair work.
    http://www.eetimes.com/author.asp?section_id=36&doc_id=1328184
     
  3. blujay

    blujay GBATemp's Official Warthog

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    If you had enough access to downgrade, couldn't you say manipulate the amount of eFuses required to be burnt in the downgrade process? So, instead of requiring 2 fuses to be burnt, require whatever the amount of burnt fuses are to be burnt before downgrading? That would provide a solution given it works.
     
  4. FAST6191

    FAST6191 Techromancer

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    The fuse level required will doubtless be in the signed range of the firmware though. It is the same reason you can't just write totally a version higher than before in the firmware to downgrade on a more conventional device.

    If you have the private keys, a dodge for them or have otherwise broken the crypto then yes I imagine you could alter all the checks to be whatever you like but at that point it does not really matter.
     
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  5. osaeed09

    osaeed09 Member

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  6. cybrian

    cybrian Advanced Member

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    How many jiggawatts does that thing take to blow?
     
  7. guyman70718

    guyman70718 Advanced Member

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    where did you get a replacement switch fuse

    /s
     
  8. SnAQ

    SnAQ GBAtemp Fan

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    What's wrong with Google?

    Skickat från min F8331 via Tapatalk
     
  9. cybrian

    cybrian Advanced Member

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    That’s no switch fuse.

    THIS is a switch fuse: [​IMG]
     
  10. planetarian

    planetarian GBAtemp Regular

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    TIL switch fuses are a thing, despite the fact that I've used them myself on numerous occasions at work