Two factors require any GC support to be behind the CPU&#x27;s MMU:<p>1) GC itself operates on virtual addresses.<p>2) If you want concurrent collection you&#x27;re probably going to need a read barrier, and that will require some GC &#x2F; MMU interaction.<p>The Azul Vega had a lot of interesting features to support GC (and other Java constructs), but the most important by far is the HW read barrier.