Again, I don't see that as cheating or violating a spec (or at least any guarantee made by Intel about x86(-64) behavior that I know of). I would assume that speculation can do just about anything (access protected memory, run illegal/protected instructions, etc), as long as any effects aren't committed to architectural state until the speculated path retires. The existence of side channels (timing information of subsequent memory accesses) for retrieving information from speculative execution paths is a different issue. Perhaps it was naive of the architects to assume this wouldn't have any consequences beyond improving performance, but I don't know what spec it is supposed to violate.

Yeah, I also have a HiFive Unleashed which is totally open, but it doesn't really aim to compete with Raptor iiuc. Until recently it also won out on open ISA, too, and the Blackbird has to be bootstrapped by the ARM BMC - which is a nonfree ISA. Power consumption is another story as well. Raptor systems is definitely the only realistic competitor to x86_64, though, for desktop and server use-cases.