Sun Microsystems VIRTUALBOX VERSION 3.1.0_BETA2 - Manual (Page 59)

3 Configuring virtual machines
replace the legacy BIOS as the primary interface for bootstrapping computers and
certain system services later.
By default, VirtualBox uses the BIOS firmware for virtual machines. To use EFI for a
given virtual machine, use the VBoxManage command line interface like this:
VBoxManage modifyvm <vmname> --firmware efi
To switch back to using the BIOS, use:
VBoxManage modifyvm <vmname> --firmware bios
One notable user of EFI is Apple’s Mac OS X, but recent Linuxes (such as Fedora 11)
and Windows (starting with Vista) can be booted using EFI as well.
Note that EFI is experimental and work in progress. Please do not enable it in a
production environment.
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