hi,
i install xen-4.2 on debian6.0(i386)/squeeze,and the dom0 kernel is 2.6.32.40.
i create a domU successfully using xen-create-image:xen-create-image --hostname localhost --ip 192.168.226.242 --verbose
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...............................
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Installation Summary
---------------------
Hostname        :  localhost
Distribution    :  squeeze
IP-Address(es)  :  192.168.226.242 
RSA Fingerprint :  4b:77:cb:03:27:ca:ae:06:08:f5:15:99:c3:6c:20:7f
Root Password   :  N/A
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but when i start this domU(xm create -c /etc/xen/localhost.cfg),error happens:
Loading, please wait...
[    6.032277] udev[1065]: starting version 164
Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Waiting for root file system ... done.
Gave up waiting for root device.  Common problems:
 - Boot args (cat /proc/cmdline)
   - Check rootdelay= (did the system wait long enough?)
   - Check root= (did the system wait for the right device?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT!  /dev/xvda2 does not exist.  Dropping to a shell!
BusyBox v1.17.1 (Debian 1:1.17.1-8) built-in shell (ash)
Enter 'help' for a list of built-in commands.
/bin/sh: can't access tty; job control turned off
(initramfs) 
 
 
and the /etc/xen-tools/xen-tools.conf is as follows:
 
install-method = debootstrap
size   = 4Gb      # Disk image size.
memory = 512Mb    # Memory size
swap   = 512Mb    # Swap size
fs     = ext3     # use the EXT3 filesystem for the disk image.
dist   = squeeze # Default distribution to install.
image  = sparse   # Specify sparse vs. full disk images.
gateway    = 192.168.226.1
netmask    = 255.255.255.0
broadcast  = 192.168.226.255
passwd=1
dir=/var/lib/xen
kernel = /boot/vmlinuz-`uname -r`
initrd = /boot/initrd.img-`uname -r`
mirror_squeeze = http://mirrors.163.com/debian/ext3_options     = noatime,nodiratime,errors=remount-ro
ext2_options     = noatime,nodiratime,errors=remount-ro
xfs_options      = defaults
reiserfs_options = defaults
btrfs_options    = defaults
serial_device = hvc0
disk_device = xvda 
 
localhost.cfg is as follows:
kernel      = '/boot/vmlinuz-2.6.32.40'
ramdisk     = '/boot/initrd.img-2.6.32.40'