QEMU

QEMU (Quick EMUlator) is a generic and open source machine emulator and virtualizer. Often it is used in conjunction with acceleration in the form of a Type-I hypervisor such as KVM (Kernel-based Virtual Machine) or Xen. If no accelerator is used, Qemu will run entirely in user-space using its built in binary translator TCG (Tiny Code Generator). Using Qemu without an accelerator is relatively inefficient and slow.

BIOS
In order to utilize KVM your processor must support either Vt-x or AMD-V which are Intel and AMD's respective technology for permitting multiple operating systems to concurrently execute operations on their processors.

To check if your hardware supports virtualization:

For a period manufacturers were shipping with virtualization turned off by default in the system BIOS. Note that changing this feature in the BIOS may actually require you to fully remove power from your system to take effect.

If KVM is installed there should be a device at.

Kernel
You need to activate the following kernel options:

Software
Install :

Frontends
To make life easier, there are multiple user-friendly front-ends to QEMU:

Permissions
In order to run a KVM accelerated virtual machine without logging into root, you must add your self to the kvm linux group.

Usage

 * See QEMU options page for common options
 * Setup a Linux guest
 * Setup a Windows guest
 * Setup a OS2WarpV3 guest

External resources

 * KVM - Community Gentoo Wiki article