&gt; AMD dropped rings in their 64 bit architecture which Intel was forced to adopt, so they&#x27;re becoming a historical curiosity.<p>Not quite. Hypervisors are operating in Ring -1, SMM is equivalent to another ring above that, and I can&#x27;t find anything about AMD64 dropping Ring 1&#x2F;2? Ring 0&#x2F;3 at least are still in use.