https://www.usenix.org/conference/woot13/workshop-program/presentation/bangert "We show that powerful computation on x86 processors is possible without executing any CPU instructions. We demonstrate a Turing-complete execution environment driven solely by the IA32 architecture’s interrupt han- dling and memory translation tables, in which the pro- cessor is trapped in a series of page faults and double faults, without ever successfully dispatching any instruc- tions."