Is there a free hypervisor that runs on a Mac Mini?

I need to run 4 instances of Mac OS X desktop (10.4 to 10.7) for our continuous integration setup (so they need to be on all the time). I've used PC hypervisors in the past (XenServer, ESXi, etc) but never for a Mac.

Is it possible to run those guest operating systems on a Mac Mini hypervisor?

Edit: Ideally, it should be managable remotely (like XenServer and ESXi), desktop virtualization software (like VirtualBox) isn't really what I had in mind.

Solution 1:

You might take a look at VirtualBox which includes a GNU GPL version as well. It offers limited/experimental capabilities to run virtualized OS X VMs, but I think Apple generally forbids virtualizing OS X via their licensing/usage terms.

Solution 2:

There are licensing issues with the scheme that you propose. See this previous answer regarding the Mac OS X EULA, which will lead you to additional information. Summary: you can't do what you want as virtualization, as versions prior to 10.7 were not available for virtualization at all per their license.

Neither VMWare or Parallels will talk publicly about circumventing the Apple EULA for pre-10.7 versions. VMWare Fusion actively prevents virtualizing the OS X client versions (there are one or more workarounds that I've seen; Google is your friend here).

I know of no hypervisor software that will allow you to accomplish your goal, either. Sorry.

Solution 3:

You have confusion between PC and Mac, they are both x86/x64, they are the same as John Hodgman and Justin Long have demonstrated before. The compatibility concern should only arise with older PowerPC based Macs, and the EFI boot process instead of BIOS.

Therefore XenServer would run fine, ESX 4.0 does not support EFI as discussed here:

http://communities.intel.com/thread/3909

Recently discussion about vSphere apparently supporting EFI on XServe:

http://lists.apple.com/archives/macos-x-server/2011/Jul/msg00080.html

What's New in VMware vSphere 5? * Support for Apple products -- vSphere 5 supports Apple Xserve servers running OS X Server 10.6 (Snow Leopard) as a guest operating system.

To read for yourself, the What's New PDF can be downloaded from this web page "VMware vSphere for Small and Midsized Busienss":

http://www.vmware.com/products/vsphere/small-business/overview.html