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4 Guest Additions

With this feature, if an application inside your virtual machine uses 3D features through theOpenGL or Direct3D 8/9 programming interfaces, instead of emulating them in software (which

would be slow), VirtualBox will attempt to use your hosts 3D hardware. This works for allsupported host platforms (Windows, Mac, Linux, Solaris), provided that your host operatingsystem can make use of your accelerated 3D hardware in the first place.

The 3D acceleration currently has the following preconditions:

1. It is only available for certain Windows, Linux and Solaris guests. In particular:

3D acceleration with Windows guests requires Windows 2000, Windows XP, Vista orWindows 7. Both OpenGL and Direct3D 8/9 (not with Windows 2000) are supported(experimental).

OpenGL on Linux requires kernel 2.6.27 and higher as well as X.org server version 1.5and higher. Ubuntu 10.10 and Fedora 14 have been tested and confirmed as working.

OpenGL on Solaris guests requires X.org server version 1.5 and higher.

2. The Guest Additions must be installed.

Note: For the basic Direct3D acceleration to work in a Windows Guest, VirtualBoxneeds to replace Windows system files in the virtual machine. As a result, the Guest

Additions installation program offers Direct3D acceleration as an option that must beexplicitly enabled. Also, you must install the Guest Additions in Safe Mode. Thisdoes not apply to the experimental WDDM Direct3D video driver available for Vistaand Windows 7 guests, see chapter 14, Known limitations, page 217 for details.

3. Because 3D support is still experimental at this time, it is disabled by default and must bemanually enabled in the VM settings (see chapter 3.3, General settings, page 47).

Note: Untrusted guest systems should not be allowed to use VirtualBoxs 3D accelera-tion features, just as untrusted host software should not be allowed to use 3D acceler-ation. Drivers for 3D hardware are generally too complex to be made properly secureand any software which is allowed to access them may be able to compromise the oper-ating system running them. In addition, enabling 3D acceleration gives the guest directaccess to a large body of additional program code in the VirtualBox host process whichit might conceivably be able to use to crash the virtual machine.

With VirtualBox 4.1, Windows Aero theme support is added for Windows Vista and Windows 7guests. To enable Aero theme support, the experimental VirtualBox WDDM video driver must beinstalled, which is available with the Guest Additions installation. Since the WDDM video driveris still experimental at this time, it is not installed by default and must be manually selected inthe Guest Additions installer by answering No int the Would you like to install basic Direct3Dsupport dialog displayed when the Direct3D feature is selected.

Note: Unlike the current basic Direct3D support, the WDDM video driver installationdoes not require the Safe Mode.

The Aero theme is not enabled by default. To enable it

supported as well. With VirtualBox 4.1 Windows Aero theme support is added for Windows Vista and Windows 7guests (experimental)

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4 Guest Additions

In Windows Vista guest: right-click on the desktop, in the contect menu select Personal-ize, then select Windows Color and Appearance in the Personalization window, in theAppearance Settings dialog select Windows Aero and press OK

In Windows 7 guest: right-click on the desktop, in the contect menu select Personalize

and select any Aero theme in the Personalization window

Technically, VirtualBox implements this by installing an additional hardware 3D driver insideyour guest when the Guest Additions are installed. This driver acts as a hardware 3D driverand reports to the guest operating system that the (virtual) hardware is capable of 3D hardwareacceleration. When an application in the guest then requests hardware acceleration throughthe OpenGL or Direct3D programming interfaces, these are sent to the host through a specialcommunication tunnel implemented by VirtualBox, and then the host performs the requested 3Doperation via the hosts programming interfaces.

4.4.2 Hardware 2D video acceleration for Windows guests

Starting with version 3.1, the VirtualBox Guest Additions contain experimental hardware 2Dvideo acceleration support for Windows guests.

With this feature, if an application (e.g. a video player) inside your Windows VM uses 2Dvideo overlays to play a movie clip, then VirtualBox will attempt to use your hosts video acceler-ation hardware instead of performing overlay stretching and color conversion in software (which

would be slow). This currently works for Windows, Linux and Mac host platforms, provided thatyour host operating system can make use of 2D video acceleration in the first place.

The 2D video acceleration currently has the following preconditions:

1. It is only available for Windows guests (XP or later).

2. The Guest Additions must be installed.

3. Because 2D support is still experimental at this time, it is disabled by default and must be

manually enabled in the VM settings (see chapter 3.3, General settings, page 47).

Technically, VirtualBox implements this by exposing video overlay DirectDraw capabilities inthe Guest Additions video driver. The driver sends all overlay commands to the host througha special communication tunnel implemented by VirtualBox. On the host side, OpenGL is thenused to implement color space transformation and scaling

4.5 Seamless windows

With the seamless windows feature of VirtualBox, you can have the windows that are displayedwithin a virtual machine appear side by side next to the windows of your host. This featureis supported for the following guest operating systems (provided that the Guest Additions areinstalled):

Windows guests (support added with VirtualBox 1.5);

Supported Linux or Solaris guests running the X Window System (added with VirtualBox1.6).

After seamless windows are enabled (see below), VirtualBox suppresses the display of theDesktop background of your guest, allowing you to run the windows of your guest operatingsystem seamlessly next to the windows of your host:

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