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MIT unveils Fractal research OS to capture chip internal behavior

Researchers at the Massachusetts Institute of Technology have developed a dedicated operating system, Fractal, to precisely analyze semiconductor internal behavior and security weaknesses. Using it, they examined security features in Apple’s M1 chip and confirmed CSV2 blocks speculative execution across privilege levels. They also found a phenomenon in which code is fetched into the instruction cache before CSV2 takes effect, potentially observable via a side channel, and identified “Phantom Speculation” in Apple silicon used in iPhones and iPads.