VirtualBox


Oracle VM VirtualBox is a free and open-source hosted hypervisor for x86 virtualization, developed by Oracle Corporation. Created by Innotek, it was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.
VirtualBox may be installed on Windows, macOS, Linux, Solaris and OpenSolaris. There are also ports to FreeBSD and Genode. It supports the creation and management of guest virtual machines running Windows, Linux, BSD, OS/2, Solaris, Haiku, and OSx86, as well as limited virtualization of guests on Apple hardware. For some guest operating systems, a "Guest Additions" package of device drivers and system applications is available, which typically improves performance, especially that of graphics.

History

VirtualBox was first offered by Innotek GmbH from Weinstadt, Germany, under a proprietary software license, making one version of the product available at no cost for personal or evaluation use, subject to the VirtualBox Personal Use and Evaluation License. In January 2007, based on counsel by LiSoG, Innotek GmbH released VirtualBox Open Source Edition as free and open-source software, subject to the requirements of the GNU General Public License, version 2.
Innotek GmbH also contributed to the development of OS/2 and Linux support in virtualization and OS/2 ports of products from Connectix which were later acquired by Microsoft. Specifically, Innotek developed the "additions" code in both Windows Virtual PC and Microsoft Virtual Server, which enables various host–guest OS interactions like shared clipboards or dynamic viewport resizing.
Sun Microsystems acquired Innotek in February 2008.
Oracle Corporation acquired Sun in January 2010 and re-branded the product as "Oracle VM VirtualBox".
In December 2019, VirtualBox started supporting only [|Hardware-based virtualization], dropping support for [|Software-based] one.

Licensing

The core package is, since version 4 in December 2010, free software under GNU General Public License version 2. The separate "VirtualBox Oracle VM VirtualBox extension pack" providing support for USB 2.0 and 3.0 devices, Remote Desktop Protocol, disk encryption, NVMe and Preboot Execution Environment boot is under a proprietary license, called Personal Use and Evaluation License , which permits use of the software for personal use, educational use, or evaluation, free of charge. Since VirtualBox version 5.1.30 Oracle defines personal use as the installation of the software on a single host computer for non-commercial purposes.
Prior to version 4, there were two different packages of the VirtualBox software. The full package was offered free under the PUEL, with licenses for other commercial deployment purchasable from Oracle. A second package called the VirtualBox Open Source Edition was released under GPLv2. This removed the same proprietary components not available under GPLv2.
Building the BIOS for VirtualBox requires the use of the Open Watcom compiler, for which the Sybase Open Watcom Public License is approved as "Open Source" by the Open Source Initiative but not as "free" by the Free Software Foundation or under the Debian Free Software Guidelines.
Although VirtualBox has experimental support for Mac OS X guests, the end user license agreement of does not permit the operating system to run on non-Apple hardware, and this is enforced within the operating system by calls to the Apple System Management Controller in all Apple machines, which verifies the authenticity of the hardware.

Emulated environment

Users of VirtualBox can load multiple guest OSes under a single host operating-system. Each guest can be started, paused and stopped independently within its own virtual machine. The user can independently configure each VM and run it under a choice of software-based virtualization or hardware assisted virtualization if the underlying host hardware supports this. The host OS and guest OSs and applications can communicate with each other through a number of mechanisms including a common clipboard and a virtualized network facility. Guest VMs can also directly communicate with each other if configured to do so.

Software-based virtualization

The feature was dropped starting with VirtualBox 6.1.

Version 6.0 and below

In the absence of hardware-assisted virtualization, VirtualBox adopts a standard software-based virtualization approach. This mode supports 32-bit guest OSs which run in rings 0 and 3 of the Intel ring architecture.
In both cases, VirtualBox uses CSAM and PATM to inspect and patch the offending instructions whenever a fault occurs. VirtualBox also contains a dynamic recompiler, based on QEMU to recompile any real mode or protected mode code entirely.
Using these techniques, VirtualBox can achieve a performance comparable to that of VMware.

Hardware-assisted virtualization

VirtualBox supports both Intel's VT-x and AMD's AMD-V hardware-assisted virtualization. Making use of these facilities, VirtualBox can run each guest VM in its own separate address-space; the guest OS ring 0 code runs on the host at ring 0 in VMX non-root mode rather than in ring 1.
Starting with version 6.1, VirtualBox only supports this method. Until then, VirtualBox specifically supported some guests only on hosts with hardware-assisted virtualization.

Device virtualization

The system emulates hard disks in one of three disk image formats:
  1. VDI: This format is the VirtualBox-specific Virtual Disk Image and stores data in files bearing a ".vdi" filename extension.
  2. VMDK: This open format is used by VMware products such as VMware Workstation and VMware Player. It stores data in one or more files bearing ".vmdk" filename extensions. A single virtual hard disk may span several files.
  3. VHD: This format is used by Windows Virtual PC and Hyper-V, and is the native virtual disk format of the Microsoft Windows operating system, starting with Windows 7 and Windows Server 2008 R2. Data in this format are stored in a single file bearing the ".vhd" filename extension.
A VirtualBox virtual machine can, therefore, use disks previously created in VMware or Microsoft Virtual PC, as well as its own native format. VirtualBox can also connect to iSCSI targets and to raw partitions on the host, using either as virtual hard disks. VirtualBox emulates IDE, SCSI, SATA and SAS controllers to which hard drives can be attached.
VirtualBox has supported Open Virtualization Format since version 2.2.0.
Both ISO images and host-connected physical devices can be mounted as CD/DVD drives. For example, the DVD image of a Linux distribution can be downloaded and used directly by VirtualBox.
By default, VirtualBox provides graphics support through a custom virtual graphics-card that is VESA compatible. The Guest Additions for Windows, Linux, Solaris, OpenSolaris, or OS/2 guests include a special video-driver that increases video performance and includes additional features, such as automatically adjusting the guest resolution when resizing the VM window
or desktop composition via virtualized WDDM drivers.
For an Ethernet network adapter, VirtualBox virtualizes these Network Interface Cards:
The emulated network cards allow most guest OSs to run without the need to find and install drivers for networking hardware as they are shipped as part of the guest OS. A special paravirtualized network adapter is also available, which improves network performance by eliminating the need to match a specific hardware interface, but requires special driver support in the guest. By default, VirtualBox uses NAT through which Internet software for end-users such as Firefox or ssh can operate. Bridged networking via a host network adapter or virtual networks between guests can also be configured. Up to 36 network adapters can be attached simultaneously, but only four are configurable through the graphical interface.
For a sound card, VirtualBox virtualizes Intel HD Audio, Intel ICH AC'97 and SoundBlaster 16 devices.
A USB 1.1 controller is emulated so that any USB devices attached to the host can be seen in the guest. The proprietary extension pack adds a USB 2.0 or USB 3.0 controllers and, if VirtualBox acts as an RDP server, it can also use USB devices on the remote RDP client as if they were connected to the host, although only if the client supports this VirtualBox-specific extension.

Feature set

; Storage emulation features
; Storage support
; Since version 3.2
; Since version 4.0
; Since version 4.1
; Since version 4.2
; Since version 4.3
; Since version 5.0
; Since version 6.0
; Since version 6.1
Some features require the installation of the closed-source "VirtualBox Extension Pack":
While Guest Additions are installed within each suitable guest virtual machine, the Extension Pack is installed on the host running VirtualBox.

Host OS support

VirtualBox can be run under Windows, GNU/Linux, macOS, Sun Solaris and FreeBSD.
Since version 5, VirtualBox has stated that they are dropping support for Windows XP hosts, thus leaving its users with Windows XP hosts vulnerable to flaws of earlier releases.