Someone

name = "rhel54"
kernel = "/usr/lib/xen/boot/hvmloader"
builder='hvm'
memory = 512
vcpus = 1
vif = [ 'mac=00:16:3e:00:00:76, bridge=xenbr0' ]
disk = [ 'tap:aio:/root/rhel54.img,xvda,w' ]
device_model = "/usr/lib/xen/bin/qemu-dm"
boot = "c"
#root = "/dev/xvda1 ro"
# Sets runlevel 3. Makes system boot past freeing unused memory error
#extra = "text console=tty0 console=xvc0 xencons=tty"
vfb = [ 'vnc=1,vnclisten=0.0.0.0,vncunused=1,vncpasswd=f00b@r' ]

sdl=0
serial='pty'
usb=1
usbdevice='tablet'