Xen Virtual Machine Notes

Installation for Xeno-Unstable (2.0 in making)

Following instructions are based on my experience in installing xen on Redhat 9 system, though it should work for any latest linux distribution.

Pre Requisites

python Twisted network application framework. You can download this from here . You then install with "tar -zxf Twisted-1.3.0.tar.gz ; cd Twisted-1.3.0 ; python setup.py install".
Make sure bridge-utils are installed (i.e, you can use brctl). If not, either install the rpm, or download the latest source from here
Xen tools require curl library and header files. It seems they are not there by default in Mandrake and Debian distributions
- For Mandrake, You can get it off of a Mandrake Cooker mirror
- On Redhat 9, make sure you have installed curl-devel rpm, thought it should be installed by default most of the times.

Building and Installation

Download the latest source code: get
- nightly snapshot tarball
- or directly pull it from bk repository Xeno-unstable.bk ( How to do this )
Build
- "make world" in the top directory will build everything - i.e. xen VMM, linux-2.4.26-xen0, linux-2.4.26-xenU and domain control tools. This downloads the linux-2.4.26 source code and ebtables-brnf-5_vs_2.4.25.diff patch. Following directories are created:
  - linux-2.4.26-xen0 - contains the linux build tree for domain0.
  - linux-2.4.26-xenU - contains the linux build tree for guest domain.
  - install - which contains the all install files generated as part of make.
- "make install" (required root user) will install everything.
  - /boot : contains xen.gz (xen VMM) and kernel images for domain 0 and guest domain - i.e. vmlinuz-2.4.26-xen0, vmlinuz-2.4.26-xen0 along with their symbol files
  - /etc/xen : contains xen config files
  - /usr/bin/: contains xen domain control tools
  - /usr/lib/python2.2/site-packages : will contain python library used by tools
  - /lib/libxc.so.1.2: library used by control tools
  - /lib/modules/linux-2.4.26-xen* - kernel modules
Updating 'grub' (Lilo won't work as Xen use multiboot standard) : add following entry in /boot/grub/grub.conf:

title Xen VM
root (hd0,x)
kernel /boot/xen.gz dom0_mem=131072 watchdog com1=115200,8n1 noht
module /boot/vmlinuz-2.4.26-xen0 root=/dev/hdax ro console=tty0

Make sure to replace x with appropriate number for your root partition. Users having separate boot partition will require to change appropriately.

Device Drivers / Modules

Xen can support all device drivers supported in source by linux. It may support binary-only driver in some cases, but not always.

Adding support for drivers/modules which are not configured by default:
- You can edit the 'install/boot/config-2.4.26-xen*" files to enable the driver/module you want. Follow it with a 'make world; make install'. 'make world' uses install/boot/config-2.4.26-xen* files if they exist instead of default ones. - Mostly you want to update the config-2.4.26-xen0 file, as device drivers are compiled in domain0. Editing config-2.4.26-xenU will be useful if you want to enable some non-device module in guest domain.
- If you don't like editing files by hand, you can go to linux-2.4.26-xen* directory and do a 'make ARCH=xen menuconfig' - remember to copy the '.config' file to 'install/boot/config-2.4.26-xen*' directory after that to keep the configuration (as make world will overwrite the .config file)