[tmyklebu]

Threading was a structurally different change from fs operations and networking. You need the compiler to cooperate when you're writing to a location in one thread and reading it from another. You can either get there using hacks built on escape hatches like 'asm volatile' or by specifying some semantics for the operation. Specifying a memory model, however imperfect, means we can move away from the implementation-dependent hacks.