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The robust futex ABI defines: #define FUTEX_OWNER_DIED 0x40000000 #define FUTEX_WAITERS 0x80000000 So how can a robust futex use a uaddr smaller than 32-bit ? And if the uaddr is 64-bit, I would expect those two values to be bits 63 and 62 (indexed from 0), but this contradicts the defines. What am I missing ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com