The domU configfile
==============
kernel = "/boot/vmlinuz-2.6.16.33-xenU"
mosule = "/boot/initrd_2.6.16-33-xenU.img"
memory = 256
name = "centos_ws"
vif = [ 'mac=00:16:3E:AA:BB:CC' ]
#dhcp = "dhcp"
disk = ['tap:aio:/misc/centos_ws.img,sda,w', 'tap:aio:/misc/swap.img,sdb,w']
root = "/dev/sda1 ro"
extra = "xencons=ttyS0 console=ttyS0 video=xenfb"
vfb = ['type=sdl']


The domU kernel Config
======================

CONFIG_XEb=y
CONFIG_XEN_INTERFACE_VERSION=0x00030203

#
# XEN
#
# CONFIG_XEN_PRIVILEGED_GUEST is not set
CONFIG_XEN_UNPRIVILEGED_GUEST=y
CONFIG_XEN_PRIVCMD=y
CONFIG_XEN_XENBUS_DEV=y
# CONFIG_XEN_BACKEND is not set
CONFIG_XEN_BLKDEV_FRONTEND=y
CONFIG_XEN_NETDEV_FRONTEND=y
CONFIG_XEN_FRAMEBUFFER=m
CONFIG_XEN_KEYBOARD=m
CONFIG_XEN_SCRUB_PAGES=y
CONFIG_XEN_DISABLE_SERIAL=y
CONFIG_XEN_SYSFS=y
CONFIG_XEN_COMPAT_030002_AND_LATER=y
# CONFIG_XEN_COMPAT_LATEST_ONLY is not set
CONFIG_XEN_COMPAT_030002=y
CONFIG_HAVE_ARCH_ALLOC_SKB=y
CONFIG_HAVE_ARCH_DEV_ALLOC_SKB=y
CONFIG_HAVE_IRQ_IGNORE_UNHANDLED=y
CONFIG_NO_IDLE_HZ=y
CONFIG_XEN_UTIL=y
CONFIG_XEN_BALLOON=y
CONFIG_XEN_DEVMEM=y
CONFIG_XEN_SKBUFF=y
CONFIG_XEN_REBOOT=y
CONFIG_XEN_SMPBOOT=y


My compilation steps
===================

cd /usr/local/src/
tar -xzf LibVNCServer-0.8.2.tar.gz
cd LibVNCServer-0.8.2
./configure
make
make install

tar -xzf xen-3.0.4_1-src.tgz
cd xen-3.0.4_1-src

vi Config.mk
  -->XENFB_TOOLS ?= y

cd configs/
vi Linux.mk
KERNELS ?= linux-2.6-xen0 linux-2.6-xenU
cd ..

--->The dom0
cp /usr/src/redhat/SOURCES/linux-2.6.16.33.tar.bz2 .
make linux-2.6-xen0-config CONFIGMODE=menuconfig
--> Only added XFS filesystem, not activated by default. 
cp linux-2.6.16.33-xen0/.config buildconfigs/linux-defconfig_xen0_x86_32


make linux-2.6-xenU-config CONFIGMODE=menuconfig
--> just saved the config file, accepting the defaults. 
cp linux-2.6.16.33-xenU.config buildconfigs/linux-defconfig_xenU_x86_32

make world
make install

create two initrd inmages. see below

When modifying the kernels, I use following commands

make linux-2.6-xen0-build
make linux-2.6-xen0-install
mkinitrd -v -f --with=ide-generic --with=xfs --preload=xfs /boot/initrd_2.6.16-33-xen0.img 2.6.16.33-xen0
make linux-2.6-xenU-build
make linux-2.6-xenU-install
mkinitrd -v -f --with=xenfb --with=xenkbd --fstab=/mnt/etc/fstab --preload=xenfb --preload=xenkbd /boot/initrd_2.6.16-33-xenU.img 2.6.16.33-xenU