Linux domU ??

[joe mcguckin <joe%via.net@localhost>]

 I'm trying to get Linux domU's going and I've gotten stuck.

I seem to have successfully installed CentOS into a file, but when I  
try to boot the domain it complains about not being able to find a
valid boot device.

Can someone offer some advice?

config file:
kernel = "/tmp/centos-5-xen-vmlinuz.img"
ramdisk = "/tmp/centos-5-xen-initrd.img"
memory  = '512'
name = 'CentOS'
vcpus=1
disk = [ 'file:/usr/xen/centos.img,xvda,w' ]
vif = [ 'bridge=bridge0' ]
boot = 'd'  #d is cdrom boot, c is disk boot.
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'preserve'

boot error:
    VFS: Cannot open root device "<NULL>" or unknown-block(0,0)
    Please append a correct "root=" boot option
    Kernel panic - not syncing: VFS: Unable to mount root fs on  
unknown-block(0,0)

adding "root=/dev/xvda' results in:

VFS: Cannot open root device "xvda" or unknown-block(0,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown- 
block(0,0)



Thanks,

Joe