It is not possible, for example, to run MacOS X in a virtual machine for the simple reason that MacOS X relies on proprietary Apple hardware and firmware which is not available in a VirtualBox virtual machine. There are, of course, limitations to this rule. In fact, in the case of guest operating systems there is a good chance that even unsupported guest operating systems will still run within a virtual machine. As with host operating systems, just because an operating systems is not listed as a supported guest does not necessarily mean it will not run. The list of supported guest operating systems is much larger than the list of supported host operating systems.

Guest operating systems are the operating systems which run within VirtualBox virtual machines. It does mean, however, that if any problems are encountered using the operating system, there will be no help offered from the authors to resolve the problem.

Just because an operating system is not listed as a supported host operating system does not necessarily mean VirtualBox will not run on that platform. It is important to understand the distinction between a supported and unsupported host operating system. In the context of VirtualBox, therefore, a supported host operating system is an operating system running directly on the hardware of the host computer which is officially supported by Sun Microsystems for running the VirtualBox virtualization environment.

In the chapter entitled An Overview of VirtualBox 2 the fact that VirtualBox runs on top of a host operating system was explained. 4 Supported VirtualBox Host Operating Systems.3 Running 64-bit VirtualBox Guest Operating Systems.2 Definition of a Guest Operating System.1 Definition of a Host Operating System.

Virtualbox 64 bit guest on 32bit host