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by bee_rider
744 days ago
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It seems like, if someone has the ability to slip an evil instruction into a proprietary ISA, they could also slip an evil instruction into their implementation of an open ISA and just not document it. RISC-V leaves room for proprietary extensions, right? Why not use that? I think RISC-V is very cool and the future, but I don’t really see how it helps here. |
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It doesn't help at all. That issue is entirely orthogonal to "open vs proprietary" ISA. The ways a compromise can be implemented are effectively infinite and need not be anything as obvious as an undocumented instruction. A predictor, for instance, can detect a specific sequence of instructions and fill the pipeline with whatever it wants: no undocumented instructions involved at all.