Lightning Talk: Volatile none of the things
summary
Finds that ARM LTO race introduced between 2007–2017 causes stores to appear delayed by up to two instruction cycles when functions move to other translation units, producing subtle ring-buffer races that let a reader spin forever and higher‑priority consumers starve real motor controllers. An off‑by‑macro in an SDM abstraction returns busy as an early return like an exception, and a DMA init bug writes to the wrong location causing memory corruption. Affected hardware: 700,000 motors, mostly in China.
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