Virtualization, in computing, is a term that refers to the various techniques, methods or approaches of creating a virtual (rather than actual) version of something, such as a virtual hardware platform, operating system (OS), storage device, or network resources.

Hardware virtualization or platform virtualization refers to the creation of a virtual machine that acts like a real computer with an operating system. Software executed on these virtual machines is separated from the underlying hardware resources. For example, a computer that is running Microsoft Windows may host a virtual machine that looks like a computer with the Ubuntu Linux operating system; Ubuntu-based software can be run on the virtual machine.[1][2]

In hardware virtualization, the host machine is the actual machine on which the virtualization takes place, and the guest machine is the virtual machine. The words host and guest are used to distinguish the software that runs on the physical machine from the software that runs on the virtual machine. The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or Virtual Machine Manager.

Different types of hardware virtualization include:

  1. Full virtualization: Almost complete simulation of the actual hardware to allow software, which typically consists of a guest operating system, to run unmodified.
  2. Partial virtualization: Some but not all of the target environment is simulated. Some guest programs, therefore, may need modifications to run in this virtual environment.
  3. Paravirtualization: A hardware environment is not simulated; however, the guest programs are executed in their own isolated domains, as if they are running on a separate system. Guest programs need to be specifically modified to run in this environment.

Hardware-assisted virtualization is a way of improving the efficiency of hardware virtualization. It involves employing specially designed CPUs and hardware components that help improve the performance of a guest environment.

Hardware virtualization can be viewed as part of an overall trend in enterprise IT that includes autonomic computing, a scenario in which the IT environment will be able to manage itself based on perceived activity, and utility computing, in which computer processing power is seen as a utility that clients can pay for only as needed. The usual goal of virtualization is to centralize administrative tasks while improving scalability and overall hardware-resource utilization. With virtualization, several operating systems can be run in parallel on a single central processing unit (CPU). This parallelism tends to reduce overhead costs and differs from multitasking, which involves running several programs on the same OS. Using virtualization, an enterprise can better manage updates and rapid changes to the operating system and applications without disrupting the user. “Ultimately, virtualization dramatically improves the efficiency and availability of resources and applications in an organization. Instead of relying on the old model of “one server, one application” that leads to under utilized resource, virtual resources are dynamically applied to meet business needs without any excess fat” (ConsonusTech).

Hardware virtualization is not the same as hardware emulation. In hardware emulation, a piece of hardware imitates another, while in hardware virtualization, a hypervisor (a piece of software) imitates a particular piece of computer hardware or the entire computer. Furthermore, a hypervisor is not the same as an emulator; both are computer programs that imitate hardware, but their domain of use in language differs.

VirtualBox is a general-purpose full virtualizer for x86 hardware, targeted at server, desktop and embedded use.

For a thorough introduction to virtualization and VirtualBox, please refer to the online version of the VirtualBox User Manual’s first chapter.

Why does HP recommend that I keep Hardware Virtualization off?

There are several attack vectors from bad drivers that can utilize VT extensions to do potentially bad things. that’s why the setting is usually in the “security” section of your BIOS UI.

additionally the smaller your instruction set, the more efficient the CPU runs at a very very low level (hence last decades interest in RISC chips). having it disabled allows the CPU to cache fewer instructions and search the cache faster.

So is there a security risk to enabling AMD-V? – Rocket Hazmat Feb 1 at 16:21
yes. Installing drivers and other very-low-level software is always risky, so its probably no more risky that grabbing a driver off a non-official download site. the big difference is that a blue-pill exploit could allow a guest to affect the host and vice-verse, which should really never be true. – Frank Thomas Feb 1 at 16:37
I disagree saying there is a security risk by enabling AMD-V. Doing a quick search on “AMD-V security” results in NO results on the first page about a security vulnerability that says a great deal. – Ramhound Feb 1 at 16:46
So, it’s off by default, because there are rootkits that pretend to by hypervisors? Guess I just gotta be careful what I download! 🙂 – Rocket Hazmat Feb 1 at 16:49

Blue Pill is the codename for a rootkit based on x86 virtualization. Blue Pill originally required AMD-V (Pacifica) virtualization support, but was later ported to support Intel VT-x (Vanderpool) as well. It was designed by Joanna Rutkowska and originally demonstrated at the Black Hat Briefings on August 3, 2006, with a reference implementation for the Microsoft Windows Vista kernel.

USB drive Ubuntu install using VirtualBox

There are many ways to create a live USB drive carrying an operating system like Ubuntu, but the method I will describe further is mainly based on using SUN’s VirtualBox.

While the method described on the Ubuntu documentations implies installing a Live CD image on a USB flash drive, which would then need to extract and load the operating system in the RAM, the method described on this page implies installing a fresh operating system on a bootable flash drive that will work the same way as from a real HDD (except the speed, of course). Thus, you should have a good bootable USB 2.0, with decent I/O data processing speeds, with at least 4GB (considering that the operating system itself weighs ~2GB, Karmic Koala).

(assuming you’ve already installed guest additions)

Click on Settings for your virtual machine, go to USB tab. Check the two boxes, since you do want USB 2.0 support. In theory, this is all, but there’s one step we will need to do afterwards to get this really working. True for Windows, Linux needs a bit more sweat.

You also need to set USB filters so that the USB devices get sent to the guest OS. USB filter is a nice feature that allows you to automatically connect USB devices to your virtual machine. Any device listed in the filter box will be plugged in when you power the guest operating system. Other devices will require that you manually connect them.

From the main Virtualbox window open the Settings dialog, then the USB section, then click the little “add filter” button on the right side of the screen. You should be able to create a filter from any currently connected USB devices.

Much like VMware Tools for VMware products, the Guest Additions expose additional functionality in the virtual machine, boost performance, enhance sharing, and more. We’ve had a long tutorial, which explains how to achieve this in both Windows and Linux virtual machines. You will need to add your user to the VirtualBox group to be able to share USB resources. You can do this from the command line or try the GUI menus.

All right, so we’re running Ubuntu with Gnome desktop. Therefore, go to System > Administration > Users and Groups. In the menu that opens, click on Manage Groups. Scroll and look for the vboxusers group. Click on the Properties button. Make sure your user is listed and checked in the Group Members field. You will need to logout and login back into the session for the effects to take change. Now, power on the virtual machine once more and see what happens.

I had the same problem and fixed it by clicking in the VirtualBox group of my user. You can access it installing gnome-system-tools (it does not come with Ubuntu 12.04 Precise Pangolin), either via the Ubuntu Software Center, Synaptic or by typing in the terminal:

sudo apt-get install gnome-system-tools

Then you head to your Dash home and type users. You will see two applications. The good one is Users and Groups.

You then have to click on Advanced settings for your user and enter your password.

Now you will be shown a window with three tabs. Click on User Privileges. Find the line that says Use Virtualbox virtualization solution and then OK.

After you’ve done this (maybe restart to be sure the host OS isn’t capturing any of the USB devices for itself–Ubuntu will try to automount the flash drive so you might also want to check and make sure that it is unmounted too) then boot into the guest OS and you should see your USB devices.

Good luck.

Edit: note on USB filters

It’s my understanding that a device being used by a guest OS with a USB filter will not be accessible by the host OS while the guest OS is running. Therefore, one should choose carefully what usb devices to create filters for.

You should create USB filters for things that you plan on only using with the guest OS (often peripherals that don’t work with the host OS and will only work with the guest OS) and when you won’t require being able to access the device from the host OS while the guest OS is running. For example I have a USB banking dongle from my bank, ICBC, that is not compatible with Linux so I use a virtualized installation of Windows XP for banking and use a USB filter to grab the USB dongle.

Examples of good devices to create filters for:

  • USB banking dongles that only work with guest OS
  • e-readers (Kindle,Nook,etc.) that you plan on using only (or primarily) with the guest OS.
  • external soundcards that only work with the guest OS or require the guest OS for full functionality

Examples of bad devices to create filters for:

  • USB input devices (mouses or keyboards) that you would like to use with the host and guest OSes. Virtualbox will allow the guest OS access to these devices by default so there is no need for the guest OS to directly control them (well, I could think of some specialized reasons but I will digress…).
  • USB storage devices that you want the guest and the host OSes to both be able to access at the same time. Instead, mount the drive on the host OS and use shared folders to share the drive to the guest OS.

Remember that to paste in the terminal you have to use CTRL+SHIFT+V, as opposed to CTRL+V

You will probably have to enter your password to allow the installation and add a Y (as in yes) to finish installing the packages.
Press alt-f2 and type ccsm (do you have compiz settings manager installed?) Scroll to the bottom and find the “move windows” icon and click on it. There is an option “constrain Y”; uncheck this and you can pull the windows where you want. If you are useing “advanced desktop settings” and dont have compiz-config-settings installed open a terminal and digit;

sudo apt-get install compizconfig-settings-manager

More reading

For a whole library full of tutorials, guides, howtos, tips and tricks on virtualization, feel free to click on any of the links below, preferably all.

VirtualBox 3 overview

Compiz Fusion in VirtualBox 3

DirectX in VirtualBox 3

Seamless mode in VirtualBox

VirtualBox desktop shortcuts

Portable VirtualBox

How to add new hard disks in VirtualBox – Tutorial

How to clone disks in VirtualBox – Tutorial

How to shrink/expand disks in VirtualBox – Tutorial

How to install VirtualBox Guest Additions – Tutorial

Network & sharing in VirtualBox – Tutorial

How to boot from CD-ROM in newer versions of VirtualBox – Tutorial