[CentOS-virt] Network Problem after update 3.0 -> 3.1: blkback

[kfx]

Hello,

I have a big problem:
Dom0 is centos5.1, domU are centos5.1. My setup is really simple, the
only thing is that I give 3 nics to the domU so I use a modified network
script (which has worked since january... since fedora 6):
"
#!/bin/sh
dir=$(dirname "$0")
"$dir/network-bridge" "$@" vifnum=0
"$dir/network-bridge" "$@" vifnum=1
"$dir/network-bridge" "$@" vifnum=2
"

So I have updated my xen dom0 from 3.0.3-rc5-8.1.15.el5 to
3.1.0-53.1.4.el5 (and kernel-xen 2.6.18-8.1.15.el5xen to
2.6.18-53.1.4.el5xen) and now my domU cant access the network. The
interfaces are good in the domU, all seems to be ok but there are no
connectivity at all (no arp entries). This message shows up on the dom0
each time I launch a domU:

blkback: ring-ref 9, event-channel 7, protocol 1 (x86_64-abi)

Do someone know what is happening ? this is very embarrassing after a
simple upgrade... Hopefully I have another identical server (Centos 5.0
with 5.1 domUs) which is still in 3.0 but I cant stay not updated.

Thanks for any help.

xm info:
host                   : host.foo.com
release                : 2.6.18-53.1.4.el5xen
version                : #1 SMP Fri Nov 30 01:21:23 EST 2007
machine                : x86_64
nr_cpus                : 4
nr_nodes               : 1
sockets_per_node       : 2
cores_per_socket       : 1
threads_per_core       : 2
cpu_mhz                : 2992
hw_caps                : bfebfbff:20100800:00000000:00000180:0000641d
total_memory           : 4095
free_memory            : 3246
xen_major              : 3
xen_minor              : 1
xen_extra              : .0-53.1.4.el5
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)
cc_compile_by          : mockbuild
cc_compile_domain      :
cc_compile_date        : Fri Nov 30 00:37:12 EST 2007
xend_config_format     : 2