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I was just trying to google and search for "??" Ghidra with no luck.

I am trying to understand what the following questions mean in this Binary (meant for SuperH2 SH-2 processor) which is Big Endian according to Ghidra. It is shown below:

Any idea of why the wildcard mnemonic couldn't be disassembled with Ghidra? Even directions to next steps in uncovering them will help :D

Thank you for your time!

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  • Can you specify what processor architecture your file is? It is possible that you are using the wrong endianness or architecture, and the ?? represent bytes that don't correspond to any known instruction in the architecture you've chosen.
    – dingo_kinznerhook
    Jul 13, 2022 at 18:31
  • @dingo_kinznerhook Thanks, I updated my description to answer you.
    – Aeonitis
    Jul 13, 2022 at 22:26

1 Answer 1

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Are you sure that this part of the binary is really code? The other instructions don't look like regular assembly code either, just a bunch of register moves without any purpose. The ?? just means that those bytes couldn't be decoded to an instruction, which is expected to happen if Ghidra is trying to disassemble data that isn't actually code. If you are sure that those bytes are really code, you might be using the wrong processor.

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  • Interesting, thank you! It might just be "zero-instruction" undefined data then, as I have had other files parse fine. I appreciate your answer!
    – Aeonitis
    Jul 14, 2022 at 11:39
  • if this turns out to be correct, please upvote and accept this answer
    – Florian Magin
    Jul 14, 2022 at 12:15
  • I'm a noob, so no rep to upvote yet. It hasn't really solved my problem so I can't accept it I'm afraid to say. I'm actually trying to reverse engineer a game, so the binary code is valid.
    – Aeonitis
    Jul 15, 2022 at 1:22
  • Did you just randomly press disassemble in places? Assembly should be contiguous (at least until control flow changes).
    – mumbel
    Jul 16, 2022 at 15:14
  • No. I just disassembled the whole assembly bytecode. I wonder if the sleigh editor instructions are complete for the SH2 processor
    – Aeonitis
    Jul 18, 2022 at 1:08

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