Qemu Tips

Qemu Video Performance

To optimize video performance under Qemu you should use a 16-bit colour depth on both the host and guest operating systems. To set 16-bit colour depth do:

$ sudo gedit /etc/X11/xorg.conf

Find the line which starts ‘DefaultDepth’ and change it so that it reads…

!DefaultDepth 16

Remeber to restart X in order to make your changes take effect.

Qemu Launcher

Qemu Launcher is a GNOME / Gtk front-end for Qemu which can Create and save multiple VM configurations and can create disk images from the GUI using dd, qemu-mkcow, and vmdk2raw for raw, COW, and VMWare converted [continued…]

Qemu Compilation

This guide was produced using Ubuntu Hoary 5.04 and Ubuntu Breezy 5.10, and Ubuntu Dapper 6.06. It’s also therefore applicable to Debian. Although most of the commands should work generically across different distributions.


Qemu packages are available in the Debian and Ubunutu repositories for version 0.6.1 or 0.7.0 (and 0.8.0 in Ubuntu Dapper 6.06), depending on what distribution and version you are using. Qemu also has an optional kernel module called KQemu, previously this was not redistributable (it now is) therefore packages for any Linux distribution may not include this module. The advantage of KQemu is much improved emulation [continued…]

Qemu Networking

NAT under Qemu

When using user-net Qemu behaves as if it was behind a firewall which blocks all incoming connections. You can use a DHCP client to automatically configure the network for the guest OS. Under QEMU 0.7.2 and below using the option


or QEMU 0.8.0 and above (you don’t need to specify this any more because it’s actually the default)

-net nic -net user

or if you have no tun/tap init script, Qemu uses a completely user mode network stack (you don’t need root privileges to use the virtual network). The virtual network configuration is the following:

Qemu [continued...]

Qemu Emulation

Qemu is a generic and open source processor emulator and has two operating modes:

  • Full system emulation. In this mode, QEMU emulates a full system (for example a PC), including a processor and various peripherials. It can be used to launch different Operating Systems without rebooting the PC or to debug system code. Full system emulation is available for x86, PowerPC, Sparc32, Sparc64 with MIPS currently under development.
  • User mode emulation (Linux host only). In this mode, QEMU can launch Linux processes compiled for one CPU on another CPU.
  • Note that QEMU has recently been updated from 0.7.2 to 0.8.0. [continued…]

    Qemu And Windows XP

    Getting Started

    The first thing we need is a virtual hard disk to install Windows XP onto. It’s a good idea to create a dedicated directory for your hard disk images. This can be anywhere – a separate partition is advisable if you have a large number of virtual machines though. This example creates a dedicated directory on the root of the filesystem, the ‘/vm’ directory.

    $ sudo mkdir /vm $ sudo chown username:group /vm $ cd /vm

    Creating a disk image

    The command below creates a compressed disk image will has a maximum capacity of 8GB. Therefore, if you [continued…]