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VirtualBox

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Sun xVM VirtualBox
Original author(s)innotek
Developer(s)Sun Microsystems
Stable release
1.6.6 / September 2, 2008; 16 years ago (2008-09-02)
Repository
Written in?
Operating systemCross-platform
Size~23MiB
TypeVirtual machine
LicenseProprietary / GNU General Public License
Websitewww.virtualbox.org

VirtualBox is an x86 virtualization software package, originally created by German software company innotek, now developed by Sun Microsystems as part of its Sun xVM virtualization platform. It is installed on an existing host operating system; within this application, additional operating systems, each known as a Guest OS, can be loaded and run, each with its own virtual environment.

Supported host operating systems include Linux, Mac OS X, OS/2 Warp, Windows XP or Vista, and Solaris, while supported guest operating systems include FreeBSD, Linux, OpenBSD, OS/2 Warp, Windows and Solaris.[1]

According to a 2007 survey by DesktopLinux.com, VirtualBox is the third most popular software package for running Windows programs on Linux desktops.[2]

History

The application was initially offered under a proprietary software license, and one version of the product, VirtualBox, is free only for personal or evaluation use, subject to the VirtualBox Personal Use and Evaluation License (PUEL).[3] In January 2007, after several years of development, VirtualBox OSE (Open Source Edition) was released as free software for commercial and private use, subject to the requirements of the GNU General Public License (GPL), version 2.[4]

The original developer, innotek, also contributed to the development of OS/2 and Linux support in virtualization[5] and OS/2 ports[6] of products from Connectix which were later acquired by Microsoft. Specifically, innotek developed the “additions” code in both Microsoft Virtual PC and Microsoft Virtual Server, which greatly improves host-guest OS interactions. OS/2 has been notoriously difficult to run virtualized in the past due to extensive ring 2 execution.

Sun Microsystems acquired Innotek in February 2008.[7][8][9]

Feature set

File:Virtualbox15seamless.png
Seamless Desktop Mode running Windows XP on Ubuntu
  • Remote Desktop Protocol (RDP) control of VM
  • iSCSI support
  • USB support, with remote devices over RDP
  • Snapshots
  • Seamless mode
  • Clipboard
  • Shared folders
  • Special drivers and utilities to facilitate switching between systems
  • Command line interaction (in addition to the GUI)
  • Remote display (useful for headless host machines)

Emulated environment

File:MacOSX VirtualBox OpenBSD.png
VirtualBox on Mac OS X running OpenBSD

While several guest operating systems can be loaded, it is usually impractical to run several at once. Each can be started, paused and stopped independently. Available RAM is the significant factor in running several operating systems simultaneously.

Hardware emulation

VirtualBox supports Intel's hardware virtualization VT-x and has experimental support for AMD's AMD-V, but does not use either of them by default.[10]

Hard disks are emulated in a special container format called "Virtual Disk Images", which is, at present, incompatible with the formats used by other virtualization solutions. These are normally stored as system files on the host operating system (with a .vdi suffix). Alternatively, VirtualBox has a unique feature in that it can connect to iSCSI targets and use them as virtual hard disks as well.

ISO images can be mounted as CD/DVD drives. For example the DVD image of a Linux distribution can be downloaded and used directly by VirtualBox. While there's no need to burn a disk, it is also possible to mount physical disks directly to a virtual machine.

By default VirtualBox provides graphics support by emulating a standard VESA card with 8 MB RAM, which can be adjusted. With the Guest Additions for Windows, Linux, or Solaris guests comes a special video driver that allows for better performance and features such as dynamically adjusting the guest resolution when the VM window is resized.

For an Ethernet network adapter, VirtualBox virtualizes these Network Interface Cards: AMD PCnet PCI II (Am79C970A), AMD PCnet-Fast III (Am79C973), Intel Pro/1000 MT Desktop (82540EM) and Intel Pro/1000 T Server (82543GC). Such a broad range of the emulated network cards allows running many operating systems without finding and installing drivers. By default, VirtualBox sets the network up with NAT through which user programs like Firefox or ssh can operate. For hosts other than Windows Vista, other options exist, such as virtual networks between guests. Up to four network adapters can be attached simultaneously.

For a sound card, VirtualBox virtualizes an Intel ICH AC'97 device or a SoundBlaster 16 card.

In the "full release" (not in the open-source edition), a USB controller is emulated so that any USB devices attached to the host can be seen in the guest. 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.

VirtualBox attempts to run as much guest code natively (that is, directly on the host processor) as possible. This works well for user-mode code running in the guest's ring 3 of the Intel ring architecture. However, the guest's ring-0 code, which will usually contain many privileged instructions, will need to be intercepted. VirtualBox has a rather novel approach to fix this conflict: It tricks the guest operating system to actually execute its ring-0 code in ring 1, which is normally unused on the Intel architecture.

If problems arise, VirtualBox has a built-in dynamic recompiler, like other virtualizers do. VirtualBox's recompiler is based on the free and open-source QEMU. In addition, however, VirtualBox automatically disassembles and, in many situations, patches the guest code to avoid future recompilations, as these are relatively expensive.[11] As a result, both the guest's ring-3 and ring-0 code can run natively most of the time, and with this combination of "traditional" recompiling and actual code patching, VirtualBox achieves a performance that is comparable to that of VMware.[12]

VirtualBox also supports Intel VT and AMD AMD-V hardware-assisted virtualization for better performance and more security. [13]

The Mac OS X release does not currently support network bridging[14].

Future development

A roadmap of features which are planned to be added to VirtualBox was released at the CommunityOne 2008 conference.[15] The roadmap included:

Proprietary vs. open source

There are two versions of the VirtualBox software.

The full VirtualBox package comes under a proprietary license, which allows using the software free-of-charge for personal and educational use and evaluation of the product.[17] Licenses for commercial use of the full VirtualBox package can be purchased from Sun.

A second version called the VirtualBox Open Source Edition (OSE) is free software released under the GNU General Public License (GPL), from which the following closed-source features are missing:[18]

  • The built-in Remote Desktop Protocol (RDP) server
  • USB support (see above) and the combination of running the RDP server with support of remote USB devices
  • iSCSI support for virtual hard disks (see above)

The free software edition was accepted into Debian unstable on 30 August 2007.[19] They are also available from backports.org in etch-backports for Debian etch users. VirtualBox OSE packages are included in the universe repository of Ubuntu 7.10 and newer[20], and are packaged into openSUSE since the 10.3 release.

USB support is slated to be open-sourced in a later version of VirtualBox[citation needed].

See also

References

  1. ^ "Status: Guest OSes" page on VirtualBox website
  2. ^ "2007 Desktop Linux Survey results revealed".
  3. ^ VirtualBox_PUEL - VirtualBox
  4. ^ http://www.virtualbox.org/wiki/GPL "The VirtualBox Open Source Edition is licensed under the GPL V2."
  5. ^ Microsoft Virtual PC Additions Version History
  6. ^ Connectix Announces First Virtual Computing Solution for OS/2 User
  7. ^ "Sun Microsystems Announces Agreement to Acquire innotek, Expanding Sun xVM Reach to the Developer Desktop" (Press release). Sun Microsystems. February 12, 2008. Retrieved 2008-02-12.
  8. ^ Ecommerce Article about the acquisition by Sun, 13 February 2008
  9. ^ "Sun Welcomes Innotek". Sun Microsystems, Inc. Retrieved 2008-02-26. On February 20 Sun completed the acquisition of innotek
  10. ^ "Developer FAQ" page on VirtualBox website
  11. ^ "Architecture" page on VirtualBox website
  12. ^ Test report by German website heise.de after the open source release, published Jan 15, 2007
  13. ^ Changelog - VirtualBox
  14. ^ Feature request ticket
  15. ^ VirtualBox 1.6 at Community One : OS Technology
  16. ^ Carl A. Waldspurger. "Memory Resource Management in VMware ESX Server". Usenix.
  17. ^ VirtualBox license page
  18. ^ "Editions" page on VirtualBox website
  19. ^ Changelog of the Debian package
  20. ^ Ubuntu - Package Search Results - virtualbox-ose
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