Oracle VM VirtualBox includes experimental support for the Extensible Firmware Interface (EFI), which is an industry standard intended to replace the legacy BIOS as the primary interface for bootstrapping computers and certain system services later.
By default, Oracle VM VirtualBox uses the BIOS firmware for virtual machines. To use EFI for a given virtual machine, you can enable EFI in the machine's Settings dialog. See Section 3.5.1, “Motherboard Tab”. Alternatively, use the VBoxManage command line interface as follows:
VBoxManage modifyvm "VM name" --firmware efi
To switch back to using the BIOS:
VBoxManage modifyvm "VM name" --firmware bios
One notable user of EFI is Apple Mac OS X. More recent Linux versions and Windows releases, starting with Vista, also offer special versions that can be booted using EFI.
Another possible use of EFI in Oracle VM VirtualBox is development and testing of EFI applications, without booting any OS.
Note that the Oracle VM VirtualBox EFI support is experimental and will be enhanced as EFI matures and becomes more widespread. Mac OS X, Linux, and newer Windows guests are known to work fine. Windows 7 guests are unable to boot with the Oracle VM VirtualBox EFI implementation.
EFI provides two distinct video interfaces: GOP (Graphics Output Protocol) and UGA (Universal Graphics Adapter). Modern OSes, such as Mac OS X, generally use GOP, while some older ones still use UGA. Oracle VM VirtualBox provides a configuration option to control the graphics resolution for both interfaces, making the difference mostly irrelevant for users.
The default resolution is 1024x768. To select a graphics resolution for EFI, use the following VBoxManage command:
VBoxManage setextradata "VM name" VBoxInternal2/EfiGraphicsResolution HxV
Determine the horizontal resolution H and the vertical resolution V from the following list of default resolutions:
- VGA
640x480, 32bpp, 4:3
- SVGA
800x600, 32bpp, 4:3
- XGA
1024x768, 32bpp, 4:3
- XGA+
1152x864, 32bpp, 4:3
- HD
1280x720, 32bpp, 16:9
- WXGA
1280x800, 32bpp, 16:10
- SXGA
1280x1024, 32bpp, 5:4
- SXGA+
1400x1050, 32bpp, 4:3
- WXGA+
1440x900, 32bpp, 16:10
- HD+
1600x900, 32bpp, 16:9
- UXGA
1600x1200, 32bpp, 4:3
- WSXGA+
1680x1050, 32bpp, 16:10
- Full HD
1920x1080, 32bpp, 16:9
- WUXGA
1920x1200, 32bpp, 16:10
- DCI 2K
2048x1080, 32bpp, 19:10
- Full HD+
2160x1440, 32bpp, 3:2
- Unnamed
2304x1440, 32bpp, 16:10
- QHD
2560x1440, 32bpp, 16:9
- WQXGA
2560x1600, 32bpp, 16:10
- QWXGA+
2880x1800, 32bpp, 16:10
- QHD+
3200x1800, 32bpp, 16:9
- WQSXGA
3200x2048, 32bpp, 16:10
- 4K UHD
3840x2160, 32bpp, 16:9
- WQUXGA
3840x2400, 32bpp, 16:10
- DCI 4K
4096x2160, 32bpp, 19:10
- HXGA
4096x3072, 32bpp, 4:3
- UHD+
5120x2880, 32bpp, 16:9
- WHXGA
5120x3200, 32bpp, 16:10
- WHSXGA
6400x4096, 32bpp, 16:10
- HUXGA
6400x4800, 32bpp, 4:3
- 8K UHD2
7680x4320, 32bpp, 16:9
If this list of default resolution does not cover your needs, see Custom VESA Resolutions. Note that the color depth value specified in a custom video mode must be specified. Color depths of 8, 16, 24, and 32 are accepted. EFI assumes a color depth of 32 by default.
The EFI default video resolution settings can only be changed when the VM is powered off.
It is currently not possible to manipulate EFI variables from
within a running guest. For example, setting the
boot-args variable by running the
nvram tool in a Mac OS X guest will not work.
As an alternative method,
VBoxInternal2/EfiBootArgs extradata can be
passed to a VM in order to set the boot-args
variable. To change the boot-args EFI
variable, use the following command:
VBoxManage setextradata "VM name" VBoxInternal2/EfiBootArgs <value>