* Q: How does VirtualBox relate to QEMU? I have seen some source files that appear to be related to his project.
A: VirtualBox makes use of QEMU in two ways: first of all, some of our virtual hardware devices have their origin in the QEMU project. We have found them to be very useful and took them as a starting point. Secondly, we have incorporated the recompiler of QEMU as a fallback mechanism for situations where our Virtual Machine Manager (VMM) cannot correctly handle a certain situation. This holds true for guest code that executes in real mode (such as bootup) and some rare scenarios at runtime. See VirtualBox architecture for details. QEMU saved us a lot of work and we are very grateful to be able to rely on it.