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Multi-OS Emulation

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PCQ Bureau
New Update

One way to run multiple OSs on a PC is to install them in a multi-boot scenario. But, this way you cannot run them simultaneously, and rebooting to switch between OSs is a hassle. Enter emulators, such as VMware or Bochs, which run different OSs simultaneously in virtual environments.

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QEMU is another such emulator, which is available for Windows, Linux and the Mac OS. In this article we will see how to emulate Linux from a live distro, such as Knoppix, on Windows using QEMU. 

Direct Hit!
Applies to: Linux and Windows users
USP: Emulate various OSs on a single machine simultaneously without sacrificing performance
Links:

http://fabrice.bellard.free.fr/QEMU/ 

QEMU works on image files (snapshot of an OS) stored on your local hard drive. It has tools that allow you to create images of a raw disk, and then use them to emulate a local hard disk inside the QEMU emulator. To start off, download QEMU for Windows from one of the mirrors listed at

http://www.freeoszoo.org/ download.php. Don't forget to download its GUI front end (Qgui) from

http://perso.wanadoo.es/comike/.

Now, install QEMU on your Windows machine. Prepare a Knoppix ISO image and copy it on your local hard drive (say C:\). You can download the latest one from

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http://www.knopper.net/knoppix/index-en.html.

Unzip the downloaded Qgui onto your hard disk and the double click on Qgui.exe to configure QEMU graphically.

In 'Global Settings', set the virtual machine path and QEMU path to c:\program files\qemu and BIOS path to c:\program files\qemu\ bios. Then set 'Disk image path' to where you have copied the Knoppix ISO image (in our case it was C:\). Now, from the Section window, select 'Disk Devices' and on the right side of the window you will get its corresponding settings. Click on 'Secondary master' and it will change to 'IDE CD-ROM:'. Check on the box next to it and select the Knoppix ISO by clicking on the browse button <....>. Then, in the same window set 'Memory size' to 128 (this is in MB). Again click on 'Global Settings' and then on Save button to commit your settings. 

QEMU command-line tips

To create a raw disk image:

Explore the folder c:\Program

file\qemu\ and execute the QEMUMenu.bat file. This will open a command window and show you four options: Create Image file, Set Memory, Set CD/ISO and Quit. Select the first option by pressing . You will be asked to enter a name (with path) for a new image file. Give the new file name without the

.img extension. Then, you will be asked to enter size (in MB) for this image file. Enter the size you need and press Enter. This will take few minutes, and a raw image file will be created and this file will be further used as local disk in a QEMU emulator. 




To install a new OS:
If you want to Install new OS on QEMU, first create an ISO image of its installer CD and then give the path of that ISO image in the QEMU configuration. 

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From the same window choose 'QEmu Version' as 'qemu.exe' and click on the Launch button. This will start the QEMU emulator window and start booting from the Knoppix image, and after few minutes you will see Knoppix running on your Windows machine. This was a small example in running a Knoppix live CD using

QEMU. 

In the same way you can install most full-flagged OSs on it, by using a raw disk image. To create new disk images and other tips on QEMU, see the accompanying box. 

Sanjay Majumder

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