How to Get to BIOS on VirtualBox
Oracle VM VirtualBox has the ability to use Extensible Firmware Interface rather than the traditional Basic Input/Output System to boot a virtual machine. Mac computers with Intel processors use EFI to boot. While 64-bit versions of Windows support EFI, no 32-bit or 64-bit Windows virtual machine is able to boot using EFI in VirtualBox. If you attempt to start a VirtualBox virtual machine and see a screen titled "EFI Shell" rather than the operating system you expected, change the virtual machine's configuration to use BIOS instead of EFI.
Launch Oracle VM VirtualBox from the "All Programs" section of the Start menu. The left side of the main VirtualBox window displays a list of your virtual machines.
Right-click the virtual machine that you want to toggle from EFI to BIOS. Select "Settings" on the context menu. A new window titled after the name of your virtual machine appears.
Click the "System" heading on the left side of the window.
Click the "Motherboard" tab at the top of the window.
Remove the check from the box labeled "Enable EFI (Special OSes Only)."
Click "OK" and double-click the virtual machine to turn it on.