Oracle VM VirtualBox (formerly Sun VirtualBox, Sun xVM VirtualBox and InnoTek VirtualBox) is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by InnoTek Systemberatung GmbH, which was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.
VirtualBox may be installed on Microsoft Windows, macOS, Linux, Solaris and OpenSolaris. There are also ports to FreeBSD[5] and Genode.[6] It supports the creation and management of guest virtual machines running Windows, Linux, BSD, OS/2, Solaris, Haiku, and OSx86,[7] as well as limited virtualization of macOS guests on Apple hardware.[8][9] For some guest operating systems, a "Guest Additions" package of device drivers and system applications is available,[10][11] which typically improves performance, especially that of graphics, and allows changing the resolution of the guest OS automatically when the window of the virtual machine on the host OS is resized.
Released under the terms of the GNU General Public License and, optionally, the CDDL for most files of the source distribution, VirtualBox is free and open-source software, though the Extension Pack is proprietary software. The License to VirtualBox was relicensed to GPLv3 with linking exceptions to the CDDL and other GPL-incompatible licenses.[12]
History
Logo of VirtualBox OSE, 2007–2010
VirtualBox was first offered by InnoTek Systemberatung GmbH, a Germany company based in Weinstadt, 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 (PUEL).[13] In January 2007, based on counsel by LiSoG, InnoTek released VirtualBox Open Source Edition (OSE) as free and open-source software, subject to the requirements of the GNU General Public License (GPL), version 2.[14]
InnoTek also contributed to the development of OS/2 and Linux support in virtualization[15] and OS/2 ports[16] 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.
Run and control guest applications from the host – for automated software deployments
Version 4.0
The PUEL/OSE separation was abandoned in favor of an open source base product and a closed source extension pack that can be installed on top of the base product. As part of this change, additional components of VirtualBox were made open source (installers, documentation, device drivers)
Paravirtualization support for Windows and Linux guests to improve time-keeping accuracy and performance
USB3 controller based on Intel's hardware implementation.[25] It is supported by any Windows version starting from Windows 8, any Linux kernel starting from 2.6.31 and Mac OS X starting from version 10.7.4.[citation needed]
Bidirectional drag and drop support for Windows, Linux and Solaris guests
The core package is, since version 4 in December 2010, free software under GNU General Public License version 2 (GPLv2). The separate "VirtualBox Oracle VM VirtualBox extension pack" providing support for USB 2.0 and 3.0 devices, Remote Desktop Protocol (RDP), disk encryption, NVMe and Preboot Execution Environment (PXE) boot is under a proprietary license, called Personal Use and Evaluation License (PUEL), which permits use of the software for personal use, educational use, or evaluation, free of charge.[30] Since VirtualBox version 5.1.30[31] Oracle defines personal use as the installation of the software on a single host computer for non-commercial purposes.[32] Unlike some software using a proprietary license, the "VirtualBox Oracle VM VirtualBox extension pack" is not source-available since it includes closed-source components, which does not make the source code publicly available.[33]
Prior to version 4, there were two different packages of the VirtualBox software. The full package was offered gratis under the PUEL, with licenses for other commercial deployment purchasable from Oracle. A second package called the VirtualBox Open Source Edition (OSE) was released under GPLv2. This removed the same proprietary components not available under GPLv2.[32][33]
Although VirtualBox has experimental support for macOS guests, the end user license agreement of macOS 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 (SMC) in all Apple machines, which verifies the authenticity of the hardware.[37]
Users of VirtualBox can load multiple guest OSes under a single host operating-system (host OS). Each guest can be started, paused and stopped independently within its own virtual machine (VM). 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.[38]
Hardware-assisted
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.[citation needed]
Starting with version 6.1, VirtualBox only supports this method.[23][2] Until then, VirtualBox specifically supported some guests (including 64-bit guests, SMP guests and certain proprietary OSs) only on hosts with hardware-assisted virtualization.[citation needed]
Devices and peripherals
VirtualBox emulates hard disks in three formats: the native VDI (Virtual Disk Image),[39] the VMDK of VMware and the VHD of Microsoft Windows. It thus supports disks created by other hypervisor software. VirtualBox can also connect to iSCSI targets and to raw partitions on the host, using either as virtual hard disks. VirtualBox emulates IDE (PIIX4 and ICH6 controllers), SCSI, SATA (ICH8M controller) and SAS controllers to which hard drives can be attached.
Both ISO images and physical devices connected to the host can be mounted as CD or DVD drives. VirtualBox supports running operating systems from live CDs and DVDs.
By default, VirtualBox provides graphics support through a custom virtual graphics-card that is VBE or UEFI GOP 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[41]
or desktop composition via virtualized WDDM drivers .
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. (Many distributions of Linux ship with this driver included.) 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.[43]
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 (Oracle provides clients for Solaris, Linux and Sun Ray thin clients that can do this, and have promised support for other platforms in future versions).[44]
Software-based
In the absence of hardware-assisted virtualization, versions 6.0 and earlier of VirtualBox could adopt 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.
The system reconfigures the guest OS code, which would normally run in ring 0, to execute in ring 1 on the host hardware. Because this code contains many privileged instructions which cannot run natively in ring 1, VirtualBox employs a Code Scanning and Analysis Manager (CSAM) to scan the ring 0 code recursively before its first execution to identify problematic instructions and then calls the Patch Manager (PATM) to perform in-situ patching. This replaces the instruction with a jump to a VM-safe equivalent compiled code fragment in hypervisor memory.
The guest user-mode code, running in ring 3, generally runs directly on the host hardware in ring 3.
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 (e.g. BIOS code, a DOS guest, or any operating system startup).[45]
Using these techniques, VirtualBox can achieve a performance comparable to that of VMware.[46][47]
The feature was dropped starting with VirtualBox 6.1.[23][2]
Features
Snapshots of the RAM and storage that allow reverting to a prior state.
"Host key" for releasing the keyboard and mouse cursor to the host system if captured (coupled) to the guest system, and for keyboard shortcuts to features such as configuration, restarting, and screenshot. By default, it is the right-side CTRL key.[48][49]
Mouse pointer integration, meaning automatic coupling and uncoupling of mouse cursor when moved inside and outside the virtual screen, if supported by guest operating system.
Seamless mode – the ability to run virtualized applications side by side with normal desktop applications
Nested paging for AMD-V and Intel VT (only for processors supporting SLAT and with SLAT enabled)
Limited support for 3D graphics acceleration (including OpenGL up to (but not including) 3.0 and Direct3D 9.0c via Wine's Direct3D to OpenGL translation in versions prior to 7.0 or DXVK in later releases)
SMP support (up to 32 virtual CPUs per virtual machine), since version 3.0
HDD format disks (only version 2; versions 3 and 4 are not supported) used by Parallels virtualization products
Limitations
3D graphics acceleration for Windows guests earlier than Windows 7 [56] was removed in version 6.1.[57] This affected Windows XP [58] and Windows Vista.
VirtualBox has a very low transfer rate to and from USB2 devices.[59][60]
Despite being an open source product, some of its features are available only in a binary form under a commercial license (see "VirtualBox Extension Pack" below).
USB3 devices pass through is not supported by older guest OSes like Windows Vista and Windows XP due to the lack of drivers however starting with version 5.0 VirtualBox offers experimental Renesas uPD720201 xHCI USB3 controller which allows to use USB3 in these operating systems through manual modification of configuration files.[61][62]
Guest Additions for macOS are unavailable at this time.[63]
Guest Additions for Windows 9x (Windows 95, 98 and ME) are not available. This results in poor performance due to the lack of graphics acceleration with the default limited color depth (external third-party software is available[64][65][66] to enable support for 32-bit color mode, resulting in better performance).[67][68][69]
EFI support is incomplete, e.g. EFI boot for a Windows 7 guest is not supported.[63][55]
Only older versions of DirectX and OpenGL passthrough are supported (the feature can be enabled using the 3D Acceleration option for each VM individually).[70]
Video RAM is limited to 128 MiB (256 MiB with 2D Video Acceleration enabled) due to technical difficulties[71] (merely changing the GUI to allow the user to allocate more video RAM to a VM or manually editing the configuration file of a VM won't work and will result in a fatal error[71]).
Windows 95/98/98SE/ME cannot be installed or work unreliably with modern CPUs (AMD Zen and newer; Intel Tiger Lake and newer) and hardware assisted virtualization (VirtualBox 6.1 and higher). This is due to these OSes not being coded correctly.[72][73][74] An open source patch has been developed to fix the issue which also addresses Windows 95/98/98SE bug which makes the system crash when running on new fast CPUs.[75]
VirtualBox 7.0 [28] and later is required to run a pristine Windows 11 guest.[76]
Windows 8.1 and higher. Support for 64-bit Windows was added with VirtualBox 1.5. Support for Windows XP was removed with VirtualBox 5.0. Support for Windows Vista was removed with VirtualBox 5.2. Windows 7 support was removed in version 6.1.
Support for (Mac) OS X 10.10 Yosemite and OS X 10.11 El Capitan was removed with VirtualBox 6.0.
Support for macOS 10.12 Sierra was officially removed with VirtualBox 6.1 (as of 6.1.16 it will still install and run, however)[77]
No support of macOS 11 Big Sur and later versions is officially provided. Users reported various technical issues when running VirtualBox on macOS Big Sur.[78]
While VirtualBox itself is free to use and is distributed under an open source license the VirtualBox Extension Pack is licensed under the VirtualBox Personal Use and Evaluation License (PUEL). Personal use is free but commercial users need to purchase a license. Oracle routinely checks log files for downloads of the VirtualBox Extension Pack from nonresidential IP addresses and contacts unlicensed users to enforce compliance.[81][failed verification]
While Guest Additions are installed within each suitable guest virtual machine, the Extension Pack is installed on the host running VirtualBox.
Derivatives
A commercial port of VirtualBox OSE with built-in support for Direct X 12.1 / Vulkan 3D API inside virtual machines has been released by the main contributor of the FreeRDP project, called Thincast Workstation.[citation needed]
^"Sun Welcomes Innotek". Sun Microsystems, Inc. Archived from the original on 2008-03-02. Retrieved 2008-02-26. On February 20 Sun completed the acquisition of Innotek
Convention: Any item in this table that has the form of "A+B" or "A+B+C" indicates a disk format that spans multiple files, where A contains the bulk of the data, and B and C are sidecar files.
/ 17 January 2023
