The xhyve hypervisor is a port of bhyve to OS X. It is built on top of Hypervisor.framework in OS X 10.10 Yosemite and higher, runs entirely in userspace, and has no other dependencies. It can run FreeBSD and vanilla Linux distributions and may gain support for other guest operating systems in the future. The --HEAD in the brew command ensures that you always get the latest changes, even if the homebrew database is not yet updated. If for any reason you don't want that simply do brew install xhyve .