3 ms·

> You absolutely can reverse chips with logic analysis. You are not going to reverse engineer a GPU with a logic analyzer and by applying currents to pins. Yo

> You absolutely can reverse chips with logic analysis. You are not going to reverse engineer a GPU with a logic analyzer and by applying currents to pins. You could replace oscilloscope with logic analyzer in the comment above and nothing changes. It’s a fantasy story. The GPU I/O is high speed PCIe and memory buses. If you want to explore the chip you connect it to a PCIe host and use the host. Connecting logic analyzers and applying current to pins does not make sense on any level. Also, if you think probing high speed signals like PCIe or memory buses with logic analyzers is easy, you’ve probably never tried it. The equipment needed to do that properly is incredibly expensive because even probing those buses slightly incorrectly or with cheap probes will make them fail to work at the speeds they use.

KellyCriterion 3mo ago
Err how would one even connect an oscilloscope to these chips, since there are only a few pins but and is digital information in very high speed?
MomsAVoxell 3mo ago
I use this type of equipment every day. I'm aware of the expense - nobody said it was cheap to do this kind of work. You might be thinking that the hobby-level logic analyzers you're used to, are what folks who are serious about doing this kind of work would be using. Just, no. >Connecting logic analyzers and applying current to pins does not make sense on any level. Tell me you've never fuzzed a chip without telling me you never fuzzed a chip. Nobody said it would be easy or cheap, or that fuzzing is the only way to do it. The OP may not have had all the details correct. But, you certainly can reverse engineer high-density digital electronics this way.
- Aurornis 3mo ago
  > You might be thinking that the hobby-level logic analyzers you're used to, are what folks who are serious about doing this kind of work would be using. Just, no. No I'm not. I'm referring to the logic analyzers and probes, and fixturing that would be necessary to probe something like this. It's not as simple as saying "wouldn't be cheap". I'm saying it's virtually impossible for a university student to do for fun with the resources available to them. > Tell me you've never fuzzed a chip without telling me you never fuzzed a chip. Please don't be snarky. Also please don't take my quotes out of context to try to attack a strawman. I'm talking about the comment thread we're responding to about someone reverse engineering the opcodes by applying current to the pins. Nobody is going to be fixturing up an nVidia GPU chip, acquiring enough probes and logic analyzer inputs to measure it, then applying currents to pins, just to reverse engineer the opcodes. You're off trying to argue something else to show off your knowledge on the internet, but you've missed the point of the thread. If someone wants to reverse engineer a GPU, the first thing you do is plug it into a system and access it through software. Nobody is going to connect logic analyzers to a million pins and re-invent PCIe signaling just because it's technically possible to do.
  - MomsAVoxell 3mo ago
    Your extreme claims that "nobody is going to do that", while I have actually seen people doing exactly that in modern universities and other reverse engineering institutions, just renders your stubborn know-best boring. Yes, people do this. Yes, it is a lot of tedious work. PCIe signaling is not a panacea - there are reasons to fuzz like this. I've also seen folks break out a tunneling electron microscope to dig deeper on de-laminated cores. >I'm saying it's virtually impossible for a university student to do for fun with the resources available to them. Now who's inventing straw man claims? "For fun"? Yes, for fun. "For profit"? Yes, for profit too. At universities? Yes, at universities. Just give it up. The world is big.
    - mikeyouse 3mo ago
      One other bit in support is that the person you’re replying to read “university student” but OP said “Post-Doc” which I guess technically is a student at a university but a post-doc EE is an exceptionally skilled and specialized role who’s likely been working on that specific problem for 8+ years.
      - MomsAVoxell 3mo ago
        I mean, there are universities with hardware reverse engineering labs in operation since the very, very beginning of hardware. I’m only persisting with the argument because the myopia is revealing.

KellyCriterion 3mo ago

Err how would one even connect an oscilloscope to these chips, since there are only a few pins but and is digital information in very high speed?

MomsAVoxell 3mo ago

I use this type of equipment every day. I'm aware of the expense - nobody said it was cheap to do this kind of work. You might be thinking that the hobby-level logic analyzers you're used to, are what folks who are serious about doing this kind of work would be using. Just, no. >Connecting logic analyzers and applying current to pins does not make sense on any level. Tell me you've never fuzzed a chip without telling me you never fuzzed a chip. Nobody said it would be easy or cheap, or that fuzzing is the only way to do it. The OP may not have had all the details correct. But, you certainly can reverse engineer high-density digital electronics this way.

Aurornis 3mo ago
> You might be thinking that the hobby-level logic analyzers you're used to, are what folks who are serious about doing this kind of work would be using. Just, no. No I'm not. I'm referring to the logic analyzers and probes, and fixturing that would be necessary to probe something like this. It's not as simple as saying "wouldn't be cheap". I'm saying it's virtually impossible for a university student to do for fun with the resources available to them. > Tell me you've never fuzzed a chip without telling me you never fuzzed a chip. Please don't be snarky. Also please don't take my quotes out of context to try to attack a strawman. I'm talking about the comment thread we're responding to about someone reverse engineering the opcodes by applying current to the pins. Nobody is going to be fixturing up an nVidia GPU chip, acquiring enough probes and logic analyzer inputs to measure it, then applying currents to pins, just to reverse engineer the opcodes. You're off trying to argue something else to show off your knowledge on the internet, but you've missed the point of the thread. If someone wants to reverse engineer a GPU, the first thing you do is plug it into a system and access it through software. Nobody is going to connect logic analyzers to a million pins and re-invent PCIe signaling just because it's technically possible to do.
- MomsAVoxell 3mo ago
  Your extreme claims that "nobody is going to do that", while I have actually seen people doing exactly that in modern universities and other reverse engineering institutions, just renders your stubborn know-best boring. Yes, people do this. Yes, it is a lot of tedious work. PCIe signaling is not a panacea - there are reasons to fuzz like this. I've also seen folks break out a tunneling electron microscope to dig deeper on de-laminated cores. >I'm saying it's virtually impossible for a university student to do for fun with the resources available to them. Now who's inventing straw man claims? "For fun"? Yes, for fun. "For profit"? Yes, for profit too. At universities? Yes, at universities. Just give it up. The world is big.
  - mikeyouse 3mo ago
    One other bit in support is that the person you’re replying to read “university student” but OP said “Post-Doc” which I guess technically is a student at a university but a post-doc EE is an exceptionally skilled and specialized role who’s likely been working on that specific problem for 8+ years.
    - MomsAVoxell 3mo ago
      I mean, there are universities with hardware reverse engineering labs in operation since the very, very beginning of hardware. I’m only persisting with the argument because the myopia is revealing.