Xen

A short Xen 3.0.3 installation report on debian etch. Im setting up a test system (Athlon XP 3200+) with software-raid 1 and LVM.

As soon as your minimal etch is up an running, we remove some packages and install additional software:

apt-get install xen-hypervisor-3.0.3 xen-utils-3.0.3 linux-image-2.6.18-3-xen-k7

Edit your /boot/grub/menu.lst

Add the following below the default entry

serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=30 serial console

Edit the lines below to tell xen about your serial console:

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=dom0_mem=262144 com1=115200,8n1 console=com1

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0,com1

Run update-grub to finalize your settings.

Edit /etc/inittab: uncomment the line starting with T0

# Example how to put a getty on a serial line (for a terminal)
#
T0:23:respawn:/sbin/getty -L ttyS0 115200 vt100
#T1:23:respawn:/sbin/getty -L ttyS1 9600 vt100

After editing /etc/inittab instruct init to reread its config:

init q

That's it. Reboot and you should be able to access your serial console with minicom.

Howto handle your installed guests …

List all running guests:

xm list

Switch Console to guest with id 2:

xm console 2

Return with console to Dom0:

Putty: press <ctrl>  + 5

or 

<ctrl> + <altgr> + 9

A sample configuration file (/etc/xen/wiggum):

kernel = "/boot/vmlinuz-2.6.18-3-xen-k7"
ramdisk = "/boot/initrd.img-2.6.18-3-xen-k7"
memory = 256
vif = [ '' ]
root = "/dev/sda1 ro"
disk = [
"file:/srv/xen/wiggum/wiggum.disk.img,sda1,w",
"file:/srv/xen/wiggum/wiggum.swp,sda2,w"
]

HINT: no virtual machine would startup until I added the ramdisk line to my config.

How to create a guest installation of debian etch. The guests hostname will be “wiggum”. The xen config file for wiggum is here

First I create a disk image of 3 GB size:

dd if=/dev/zero of=wiggum.disk.img bs=1M count=1 seek=3072

next I format the image file with ext3 filesystem:

mke2fs -F -j wiggum.disk.img

create 256 MB swap file

dd if=/dev/zero of=wiggum.swp bs=1024 count=262144
mkswap wiggum.swp

mount the disk image file to /mnt

mount -o loop wiggum.disk.img /mnt/

debootstrap

debootstrap --arch i386 etch /mnt http://your.mirror/debian

copy the kernel modules to /mnt/lib/modules

cp -ax /lib/modules/2.6.18-3-xen-k7/ /mnt/lib/modules/

create a valid fstab, something like this:

# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/sda1       /               ext3   defaults              1 1
/dev/sda2       none            swap   sw                    0 0
proc            /proc           proc   defaults              0 0
sysfs           /sys            sysfs  noauto                0 0
usbfs           /proc/bus/usb   usbfs  noauto                0 0
devpts          /dev/pts        devpts mode=0620,gid=5       0 0

copy /etc/passwd and /etc/shadow to /mnt/etc

edit hostname and hosts to meet your needs

echo wiggum > /mnt/etc/hostname
echo "127.0.0.1       localhost" > /mnt/etc/hosts
echo "127.0.1.1       wiggum.domain.lan     wiggum" >> /mnt/etc/hosts

deaktivate TLS and umount

mv /mnt/lib/tls /mnt/lib/tls.disabled
umount /mnt

puh, now it's time to bootup your guest:

xm create /etc/xen/wiggum -c

wiggum should boot up … Login to your brand new guest and countinue with the configuration:

the network is still down and needs some tune up:
/etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
allow-hotplug eth0
iface eth0 inet dhcp

HINT: if dhcp is unavailable or doesn't work use a static ip configuration.

apt-get install locales console-data
dpkg-reconfigure locales console-data

# with libc6-xen you won't have any problem with TLS in the future :-)
apt-get install libc6-xen

Install them:

apt-get install xen-tools

Creating a DomU with xen-tools reduces your effort to a single command:

xen-create-image \
--hostname testman \
--lvm vgdrbd0 \
--dhcp \
--dist etch \
--swap 256Mb \
--memory 128Mb \
--passwd \
--kernel /boot/vmlinuz-2.6.18-4-xen-amd64 \
--initrd /boot/initrd.img-2.6.18-4-xen-amd64 \
--debootstrap

man xen-create-image will give you detailed information about the options used above.

Useful resources:

• http://www.pug.org/index.php/Xen-Installation