Description of problem:
I need to attach some PCI devices (LAN adapter) directly to a domU.
pciback module has been loaded and pci-devices bound to it.

But either putting "pci=['09:00.0','09:00.1']" into the config file nor the
cmdline option "pci=09:00.0" work...

Error Message:
Error: function takes exactly 4 arguments (3 given)

Version-Release number of selected component (if applicable):
xen-3.0.3-41.el5


How reproducible:
always


Steps to Reproduce:
1. create a VM config like this (with default RHEL5 guest installation):
name = "testvm"
uuid = "c2436648-0f2c-80c7-0c19-9ce1e5d5f6d4"
maxmem = 256
memory = 256
vcpus = 1
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=de" ]
disk = [ "phy:/dev/xen03-domU/fw-ext,xvda,w" ]
vif = [ "mac=00:16:3e:10:e6:85,bridge=xenbr1" ]
pci=['09:00.0','09:00.1']

2. In dom0 try 
~# xm create testvm
or (if pci= setting is not in config)
~# xm create testvm pci=09:00.0 pci=09:00.1

Actual results:
error, the domain can not be started

Expected results:
created domain with pci devices attached directly to it