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

For details, see the VMware Compatibility Guide at

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 guest operating system installer partitions the disk in a particular format, depending on which firmware the installer was booted from. If you change the firmware, you will not be able to boot the guest.

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. Select the guest operating system family from the Guest OS Family drop-down menu.
  2. Select a guest operating system version from the Guest OS Version drop-down menu.
  3. If you selected Other as the guest operating system family, and Other (32-bit) or Other (64-bit) for the version, type a name for the operating system in the text box.
  4. Click Next.