Table of Contents
The previous chapter covered getting started with VirtualBox and installing operating systems in a virtual machine. For any serious and interactive use, the VirtualBox Guest Additions will make your life much easier by providing closer integration between host and guest and improving the interactive performance of guest systems. This chapter describes the Guest Additions in detail.
As said in Sectioná1.1, “Virtualization basics”, the Guest Additions are designed to be installed inside a virtual machine. They consist of device drivers and system applications for the guest operating system that optimize the guest for better performance and usability.
The VirtualBox Guest Additions for all supported guest operating
systems are provided as a single CD-ROM image file which is called
VBoxGuestAdditions.iso. To install the
Guest Additions for a particular VM, you mount this ISO file in your VM as
a virtual CD-ROM and install from there.
Please see Sectioná1.5, “Supported guest operating systems” for details on what guest operating systems are fully supported with Guest Additions by VirtualBox. The Guest Additions offer the following features:
To overcome the limitations for mouse support that were described in Sectioná3.4.1.1, “Capturing and releasing keyboard and mouse”, this provides you with seamless mouse support. Essentially, a special mouse driver is installed in the guest that communicates with the "real" mouse driver on your host and moves the guest mouse pointer accordingly. You will only have one mouse pointer and pressing the Host key is no longer required to "free" the mouse from being captured by the guest OS.
While the virtual graphics card which VirtualBox emulates
for any guest operating system provides all the basic features,
the custom video drivers that are installed with the Guest
Additions provide you with extra high and non-standard video modes
as well as accelerated video performance. In addition, with
Windows and recent Linux, Solaris and OpenSolaris guests, when the
Guest Additions are installed, you can resize the virtual
machine's window, and the video resolution in the guest will be
automatically adjusted (as if you had manually entered an
arbitrary resolution in the guest's display settings). For Linux
and Solaris guests, the Xorg server version 1.3 or later is required
for automatic resizing (the feature has been disabled on Fedora
9 guests due to a bug in the X server they supply). The
server version can be checked with
Xorg -version.
With the Guest Additions installed, VirtualBox can ensure that the guest's system time is better synchronized. This fixes the problem that an operating system normally expects to have 100% of a computer's time for itself without interference, which is no longer the case when your VM runs together with your host operating system and possibly other applications on your host. As a result, your guest operating system's timing will soon be off significantly. The Guest Additions will re-synchronize the time regularly.
These provide an easy way to exchange files between the host and the guest. Much like ordinary Windows network shares, you can tell VirtualBox to treat a certain folder as a shared folder, and VirtualBox will make it available to the guest operating system as a network share. For details, please refer to Sectioná4.6, “Folder sharing”.
With this feature, the individual windows that are displayed on the desktop of the virtual machine can be mapped on the host's desktop, as if the underlying application was actually running on the host. See Sectioná4.7, “Seamless windows” for details.
With the Guest Additions installed, the clipboard of the guest operating system can optionally be shared with your host operating system; see Sectioná3.7.1, “General settings”.
(Credentials passing; Windows guests only) For details, please see Sectioná9.2, “Automated Windows guest logons (VBoxGINA)”.