Xen全虚拟化实例

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前言(Preface)

This is an example of obtaining full virtualization environment by Xen 3.0.2 packaged in SUSE 10.1.

这是通过SUSE 10.1的Xen 3.0.2包获得全虚拟化环境的例子。

In this document, topics specified for full virtualization-not the conventional paravirtualization- are discussed. For general information , see Xen's document site.Some of these may be included in SUSE 10.1's /usr/share/doc/packages/xen.

在这篇文档中，我们讨论的话题是针对全虚拟化技术而不是通常的半虚拟化技术。你可以在Xen's document site上查阅整体信息，在SUSE 10.1的/usr/share/doc/packages/xen里面也包含了其中一些信息。

In some environment, this example might freeze your whole system. Then you would have to use hardware reset. I strongly recommend you would try it in an experimental environment, not the important one. A solution for freezing problem may help.

Running NetworkManager somehow interferes with the way Xen set up ethernet bridging. Go to YaST/Network Devices/Network Card, and select Traditional Method with ifup

Environment

Hardware

For Full Virtualization, a CPU with virtualization support is required. The list of suitable CPUs may be helpful.

An ATX PC was assembled for this attempt.

• CPU: Intel Core Duo T2500
• RAM: 1024 MB
• Motherboard: ASUS N4L-VM-DH (This motherboard a needs a power unit with 24pin connector).
• HDD:Serial ATA

SUSE version

SUSE Linux 10.1 Released, for x86 architecture

Xen Installation

At the same time of SUSE installation. Select "XEN virtualization" category in YaST software management.

Binary OS for DomU

Windows XP Professional

Method

Create a Blank Disk Image to install

#cd /var/lib/xen/images
#dd if=/dev/zero of=windisk.img bs=1k seek=4096k count=1
#dd if=/dev/zero of=windisk.img bs=1k count=1 conv=notrunc

(The third command line seems not absolutely required)

Edit Configuration File

Edit /etc/xen/examples/xmexample.hvm to make two types of configuration file. One for booting from CD at the first seup, and booting from HDD afterwards.

• myxm.hvm(for CD boot)

Modify following lines and leave the rest as default.

# Initial memory allocation (in megabytes) for the new domain.
memory = 384 

disk = [ 'file:/var/lib/xen/images/windisk.img,ioemu:hda,w' ]

on_poweroff = 'destroy'
on_reboot   = 'destroy'
on_crash    = 'destroy'

# Disk image or device which appears as a CD drive to the guest
#   !! this parameter is no longer supported in versions > 3.0.2 of Xen 
cdrom='/dev/sr0' #set proper device name for your own environment!

Later versions of Xen do not support the cdrom parameter any more but integrate it into the disk = statement.

You can either specify an ISO image like this

# This is for Xen 3.0.3 or later
disk = [ 'file:/var/lib/xen/images/windisk.img,ioemu:hda,w', 'file:/tmp/install-image.iso,hdc:cdrom,r' ]

(hdc means master drive on secondary IDE channel)

or map the physical CD drive of your system to the guest

# This is for Xen 3.0.3 or later
disk = [ 'file:/var/lib/xen/images/windisk.img,ioemu:hda,w', 'phy:/dev/cdrom,hdc:cdrom,r' ]

# boot on floppy (a), hard disk (c) or CD-ROM (d) 
#  the drive letters are allocated dynamically by Windows
boot='d'

# enable SDL library for graphics, default = 0
sdl=1
# enable VNC library for graphics, default = 1
vnc=0 
# enable spawning vncviewer(only valid when vnc=1), default = 1
vncviewer=0

• myxmhdd.hvm(for HDD boot)

Save myxm.hvm as myxmhdd.hvm and edit only boot description.

# boot on floppy (a), hard disk (c) or CD-ROM (d) 
boot='c'

Full description of an example of hvm file is shown in the discussion page.

Locate myxm.hvm and myxmhdd.hvm in /etc/xen/vm.

Spare Dom0 memory for DomU

This may improve stability of VM for Windows. I got an info in Xen mailing list it's worth to try to spare bigger memory to domU if it wouldn't work well.

#xm mem-set 0 <properly reduced size>

First Boot of VM for Windows Setup

Be sure to insert Windows setup disk in the drive first.

#cd /etc/xen/vm
#xm create myxm.hvm

After a pause, a little window appears and setup begins (a blue-screend one in the snapshot below)

Proceed the setup as usual in Window's way. When copying of files is done, this window dissapears. You should reboot the vm manually.

Boot VM from HDD

In /etc/xen/vm directory,

#xm create myxmhdd.hvm

The little window reappeard and Windows setup continues. When you use mouse in VM window, the cursor is grabbed within it. To go back to SUSE desktop, press Ctrl+Alt keys.

SUSE Linux 10.2 Alpha2

Full virtualization could be built only with GUI operation of YaST VM Management in above hardware environment.

In above hardware environment, Installation of the SUSE development version by YaST may fail (Alpha2 Bug). Use text mode in Installation.

Practical use of Full Virtualized Windows

Can this Full Virtualized Windows VM be used practically, for example creating documents or programming? Absolutely. See some report on this topic, it's been created in Windows VM using Openoffice.org 2.0!

For best speed using a Windows VM as desktop, use Windows 'Remote Desktop Connection' or, from linux, rdesktop (various flavours of this for different environments are shown here). If you are on the same lan it is hardly noticeable that you are not sat at the desktop, except that screen font edge smoothing is not available.

You can also tweak settings in the Windows VM, and replace one system file, to allow multiple concurrent remote desktop users with a single Windows installation. Just google for something like 'concurrent windows xp pro remote desktop sessions'. Consider the licensing issues, though.