The guest operating system that you select affects the supported devices and number of virtual CPUs available to the virtual machine.

The New Virtual Machine wizard does not install the guest operating system. The wizard uses this information to select appropriate default values, such as the amount of memory needed.

When you select a guest operating system, BIOS or Extensible Firmware Interface (EFI) is selected by default, depending on the firmware supported by the operating system. Mac OS X Server guest operating systems support only EFI. If the operating system supports BIOS and EFI, you can change the default from the Options tab of the Virtual Machine Properties editor after you create the virtual machine and before you install the guest operating system. If you select EFI, you cannot boot an operating system that supports only BIOS, and the reverse.

Important: Do not change the firmware after the guest operating system is installed.

The Mac OS X Server must run on Apple hardware. You cannot power on a Mac OS X Server if it is running on other hardware.


  1. On the Guest Operating System page of the New Virtual Machine wizard, select an operating system family.
  2. Select an operating system and version from the drop-down menu and click Next.
    If any of the total cores available on the host, the maximum virtual CPUs supported by the virtual machine hardware version, or the maximum supported CPUs on the guest operating system equal 1, the virtual machine CPU count is set to 1 and the Memory page opens.
  3. If you selected Other (32-bit) or Other (64-bit), enter a name for the operating system in the text box.
  4. Click Next.

What to do next

You can add memory or CPUs for the virtual machine.