> Speculative instruction fetches fetch code from "a location that you never asked it to execute code at" by design. If it already knew you asked it to execute

> Speculative instruction fetches fetch code from "a location that you never asked it to execute code at" by design. If it already knew you asked it to execute code there, it wouldn't be speculative. Sure, but (a) the speculation is supposed to be transparent; and (b) ARM's response to a failure in speculative execution is arguably broken. > The Armv8/9-A architecture reference manual Sure, but before then marking memory as not readable would make it non-executable, and also mostly before then there was no or minimal speculation. > then your code is not "perfectly good and correct". Certainly it won't work on that machine. It might have worked perfectly well on prior machines, and we could argue all day about how reasonable ARM's implementation decisions were, but I will merely say that a documented flaw is, in fact, still a flaw.