Hello. i want to setup the ubuntu virtual machine in the RHEL5 OS, and i have install the package of xen and xen-libs from the origine package in the RHEL5 ISO.xen-3.0.3-25.el5.x86_64.rpm  and xen-libs-3.0.3-25.el5.x86_64.rpm
 because i use the AMD 3800+ platform . I follow the instruction copy the /etc/xen/xmexample.hvm as /etc/xen/ubuntu2 
#============================================================================
# Python configuration setup for 'xm create'.
# This script sets the parameters used when a domain is created using 'xm create'.
# You use a separate script for each domain you want to create, or 
# you can set the parameters for the domain on the xm command line.
#============================================================================
import os, re
arch = os.uname()[4]
if re.search('64', arch):
    arch_libdir = 'lib64'
else:
    arch_libdir = 'lib'
#----------------------------------------------------------------------------
# Kernel image file.
kernel = "/usr/lib/xen/boot/hvmloader"
# The domain build function. HVM domain uses 'hvm'.
builder='hvm'
memory = 128
# Shadow pagetable memory for the domain, in MB.
# Should be at least 2KB per MB of domain memory, plus a few MB per vcpu.
shadow_memory = 8
# A name for your domain. All domains must have different names.
name = "ExampleHVMDomain"
# 128-bit UUID for the domain.  The default behavior is to generate a new UUID
# on each call to 'xm create'.
#uuid = "06ed00fe-1162-4fc4-b5d8-11993ee4a8b9"
#-----------------------------------------------------------------------------
# the number of cpus guest platform has, default=1
#vcpus=1
# enable/disable HVM guest PAE, default=0 (disabled)
#pae=0
# enable/disable HVM guest ACPI, default=0 (disabled)
#acpi=0
# enable/disable HVM guest APIC, default=0 (disabled)
#apic=0
# List of which CPUS this domain is allowed to use, default Xen picks
#cpus = ""         # leave to Xen to pick
#cpus = "0"        # all vcpus run on CPU0
#cpus = "0-3,5,^1" # run on cpus 0,2,3,5
# Optionally define mac and/or bridge for the network interfaces.
# Random MACs are assigned if not given.
#vif = [ 'type=ioemu, mac=00:16:3e:00:00:11, bridge=xenbr0, model=ne2k_pci' ]
# type=ioemu specify the NIC is an ioemu device not netfront
vif = [ 'type=ioemu, bridge=xenbr0' ]
#----------------------------------------------------------------------------
# Define the disk devices you want the domain to have access to, and
# what you want them accessible as.
# Each disk entry is of the form phy:UNAME,DEV,MODE
# where UNAME is the device, DEV is the device name the domain will see,
# and MODE is r for read-only, w for read-write.
#disk = [ 'phy:hda1,hda1,r' ]
disk = [ 'file:/var/images/min-el3-i386.img,hda,w', ',hdc:cdrom,r' ]
#----------------------------------------------------------------------------
# Configure the behaviour when a domain exits.  There are three 'reasons'
# for a domain to stop: poweroff, reboot, and crash.  For each of these you
# may specify:
#
#   "destroy",        meaning that the domain is cleaned up as normal;
#   "restart",        meaning that a new domain is started in place of the old
#                     one;
#   "preserve",       meaning that no clean-up is done until the domain is
#                     manually destroyed (using xm destroy, for example); or
#   "rename-restart", meaning that the old domain is not cleaned up, but is
#                     renamed and a new domain started in its place.
#
# The default is
#
#   >#   on_reboot   = 'restart'
#   on_crash    = 'restart'
#
# For backwards compatibility we also support the deprecated option restart
#
# restart = 'onreboot' means >#                            on_reboot   = 'restart'
#                            on_crash    = 'destroy'
#
# restart = 'always'   means >#                            on_reboot   = 'restart'
#                            on_crash    = 'restart'
#
# restart = 'never'    means >#                            on_reboot   = 'destroy'
#                            on_crash    = 'destroy'
#>#on_reboot   = 'restart'
#on_crash    = 'restart'
#============================================================================
# New stuff
device_model = '/usr/' + arch_libdir + '/xen/bin/qemu-dm'
#-----------------------------------------------------------------------------
# boot on floppy (a), hard disk (c) or CD-ROM (d) 
# default: hard disk, cd-rom, floppy
boot="dca"
#-----------------------------------------------------------------------------
#  write to temporary files instead of disk image files
#snapshot=1
#----------------------------------------------------------------------------
# enable SDL library for graphics, default = 0
sdl=1
#----------------------------------------------------------------------------
# enable VNC library for graphics, default = 1
vnc=0
#----------------------------------------------------------------------------
# address that should be listened on for the VNC server if vnc is set.
# default is to use 'vnc-listen' setting from /etc/xen/xend-
config.sxp
#vnclisten="127.0.0.1"
#----------------------------------------------------------------------------
# set VNC display number, default = domid
#vncdisplay=1
#----------------------------------------------------------------------------
# try to find an unused port for the VNC server, default = 1
#vncunused=1
#----------------------------------------------------------------------------
# enable spawning vncviewer for domain's console
# (only valid when vnc=1), default = 0
#vncconsole=0
#----------------------------------------------------------------------------
# set password for domain's VNC console
# default is depents on vncpasswd in xend-config.sxp
vncpasswd=''
#----------------------------------------------------------------------------
# no graphics, use serial port
#nographic=0
#----------------------------------------------------------------------------
# enable stdvga, default = 0 (use cirrus logic device model)
stdvga=0
#-----------------------------------------------------------------------------
#   serial port re-direct to pty deivce, /dev/pts/n 
#   then xm console or minicom can connect
serial='pty'
#-----------------------------------------------------------------------------
#   enable sound card support, [sb16|es1370|all|..,..], default none
#soundhw='sb16'
#-----------------------------------------------------------------------------
#    set the real time clock to local time [default=0 i.e. set to utc]
#localtime=1
#-----------------------------------------------------------------------------
#    start in full screen
#full-screen=1   
#-----------------------------------------------------------------------------
#   Enable USB support (specific devices specified at runtime through the
#   monitor window)
#usb=1
#   Enable USB mouse support (only enable one of the following, `mouse' for
#         PS/2 protocol relative mouse, `tablet' for
#         absolute mouse)
#usbdevice='mouse'
#usbdevice='tablet'
#-----------------------------------------------------------------------------
#   Set keyboard layout, default is en-us keyboard. 
#keymap='ja'
 
 
in the red word is i have modified ,these are 
 
boot="cda"  =>  boot="dca"  
sdl=0  => sdl=1
vnc=1 => vnc=0
 
and no more has been modified .
but when i use command
 
xm create ubuntu2 
 
it fails  with the notion of 
Using config file "/etc/xen/ubuntu2".
Error: Disk image does not exist: /var/images/min-el3-i386.img
i make sure /etc/xen/ubuntu2 is the config file i edit
 
and the /var/images/min-el3-i386.img exists when i use command
dd if=/dev/zero of=/var/images/min-el3-i386.img bs=1M count=128
to make it
i google the website to figure out this problem . As a result , i notice that some said just because the 
selinux not allow the file access ,and i add the command 
semanage fcontext -a -f "" -t xen_image_t '/var/images(/.*)?'
and making sure the rule is in the context as i type command 
semanage fcontext -l | grep xen_image
/var/images(/.*)?                                  all files          system_u:object_r:xen_image_t:s0
this resolution does not work .
can someone tell me how to solve this problem when i create the xen vm.
thank you
 
regards
jeppeter