No, this works fine for symmetric configs. The OS can treat all the CPUs the same once they've booted, you just need to pick one of them arbitrarily to run the

No, this works fine for symmetric configs. The OS can treat all the CPUs the same once they've booted, you just need to pick one of them arbitrarily to run the initial bootup code, which is conventionally the one with ID 0. Calling that one 'primary' and the others 'secondaries' is just convenient terminology when dealing with this kind of bootup code.