QEMU

The QEMU documentation provides information on many obscure options, but you may be able to get by with just a few.

QEMU is a fast processor emulator that uses dynamic translation to achieve a reasonable speed while being easy to port to new host CPUs.

The guest side of the channel would be supported by an open-source, multiplatform qemu-guest-tools package.

If you'd like to leave QEMU and return the mouse context to your host operating system, press Ctrl-Alt.

This utility can create images with various formats, but the best (for qemu) is called qcow (or qemu copy-on-write).

QEMU is an open source emulator for complete computer systems as well as providing a complete virtualization solution (via emulation).

Learn more about cfLinux; the author used this small distribution to demonstrate installing an operating system into a QEMU machine.

Although QEMU is a platform emulator, it provides software emulation for a variety of hardware devices, including NICs.

KQEMU is not part of the standard Linux kernel, though; you must download it from the QEMU Web site or install it in a separate package.

Building and installing QEMU is about as simple as you expect using standard GNU tools.

For instance, QEMU's emulated hard disks return a model string of "QEMU HARDDISK" rather than a real hard disk manufacturer and model.

Both of these virtualization solutions support virtio (along with QEMU for system emulation and libvirt for virtualization management).

The first step is to download the QEMU package for your particular host (see the Resources section for QEMU download information).

First, when the QEMU window is in focus, it owns the mouse and keyboard and all events are directed to it.

After you download and install QEMU, the next step is to download an OLPC XO image.

When x86 code is being emulated on an x86 host system, near native performance can be achieved using what is called the QEMU accelerator.

QEMU executes as a user-space process, coordinating with the kernel for guest operating system requests.

Using QEMU as a machine emulator allows you to experiment with many operating systems for which you may not have a spare machine available.

To use QEMU for cross-platform development, you must first set it up and install guest operating systems on it.

This local URI attaches to the system mode daemon for the local QEMU driver.

Thus, you may need to install the software from source code, which you can obtain from the QEMU Web site (see Resources for a link).

QEMU achieves dynamic translation by first converting target instructions into micro operations.

This section describes the two QEMU modes of operation and also some of the interesting aspects of the QEMU dynamic translator.

Using QEMU as a PC system emulator provides a wide variety of peripherals.

The guest operating system interfaces to the KVM module using a modified QEMU process for PC hardware emulation.

Visit the QEMU Web site to download QEMU and related tools, read the extensive documentation, and find links to other resources.

Using qemu, you specify your hard disk image with the hda option and the cdrom (file where your ISO image resides) with the cdrom option.

The QEMU accelerator is an optional step, but I recommend it because it results in greater performance.

QEMU is a big package with many options, many of which may be interesting to at least some developers.

For more details on QEMU and its internal operation, see Resources.

Summary: QEMU is an open source emulator for complete PC systems.

QEMU supports two operating modes: user-mode emulation and system-mode emulation.

With QEMU set up and running a guest operating system, you can now begin your software development.

A full QEMU installation includes several binaries, each of which emulates a different CPU architecture.

In this article, you used the ReactOS as a means to demonstrate a domain on QEMU.

You must have the kvm and qemu user-space applications, as well.

Another important QEMU launch option is -boot, which specifies the boot device.

Under Linux, QEMU sessions consume little CPU time except when the guest operating system is doing work.

Binaries with names of the form qemu-arch provide user-mode emulation for their respective architectures.

Listing 2 gives the QEMU accelerator download, build, and installation instructions.

Bochs is similar to QEMU in that it provides full system emulation.

QEMU is a great way to try a new operating system without spending time for the install.

The final step in preparation is to download and prepare the QEMU image for the XO-1 laptop.

You can read more about QEMU in Tim's article " System emulation with QEMU" (developerWorks, September 2007).

Note: At the end of Listing 2, the QEMU accelerator kernel module is installed.

To return to the XO-1, click within the Sugar frame, and the mouse context returns to QEMU.

You can learn more about QEMU in System emulation with QEMU (developerWorks, September 2007).

When this command is issued, a new QEMU window that represents the emulated machine appears (see Figure 2).

There, you'll also find documentation, APIs, and the current status of QEMU.

The second component provides for PC platform emulation, which is provided by a modified version of QEMU.

QEMU provides a special command to create a hard disk called qemu-img.

You can find details about the virtual hardware in the QEMU documentation.

For QEMU, the protocol ends at the QEMU monitor.

After downloading and untaring the QEMU distribution, configure, make, and then make install, and you're done (see Listing 1).

To begin installing or using QEMU, you must launch the program with appropriate options to enable use of the emulator.

But KVM makes use of QEMU for device emulation as a separate process in the user space (see Figure 1).

You can learn more about QEMU in the Resources section.

By default, QEMU provides the guest operating system just 128MB of RAM.

QEMU provides two modes of emulation.

QEMU supports two modes of operation.

Before you can use QEMU in system emulation mode, you must install a guest operating system.

Recall Figure 4 in the KVM discussion: In addition to the guest operating systems, there's the KVM-modified QEMU.

To use qemu or kvm, you can create a hard disk using qemu-img create vm. img 10G.

Type qemu-system-arch -M ? to learn what the legal values are for your architecture.

As I write, the latest stable version of QEMU is 0. 11. 1, but a 0. 12 release candidate version is also available.

An EFI image is provided on the QEMU site, so that particular condition is easy to satisfy.

Since you're installing a KVM package and not building KVM yourself from source, you can use qemu-kvm but not qemu-system-x86_64.

In addition to emulating a processor, QEMU permits emulation of all necessary subsystems, such as networking and video hardware.

The binary filenames take the form qemu-system-arch, where arch is an architecture code, such as ppc for PowerPC or x86_64 for x86-64.

For example, you should understand your options for QEMU installation as well as installation of necessary support files such as firmware.

The next step is to install the operating system on your hard disk. This is done simply with qemu

You need to rebuild QEMU -- I learned how by following instructions in a QEMU forum (see Resources). Get these packages

After you install the QEMU and OLPC XO images on the host operating system, boot the OLPC laptop with the following command

Displays QEMU help Specifies onion skin translucency value (as percent)

A user-space component for emulating PC hardware; currently, this is handled in the user space and is a lightly modified QEMU process

Mount the disk image (with the qemu image turned off) using