Qemu 0.10.50 CAN NOT get ip from dhcp server

[John Wong <johnw@wonghome.net>]

I notice that, when i use qemu 0.10.50 (which from kvm-0.87.tar.gz), the
guest OS CAN NOT get the ip from dhcp server.
When i use qemu 0.10.0 (which from debian's kvm-0.85 package), the guest
OS CAN get the ip from the SAME dhcp server.

Please help, thank you.

My kvm network use bridge mode

My kvm launch script:

#!/bin/sh

NUM="9"
IMG="./openbsd-amd64.qcow2"
CDROM="/ntfs2/iso-cdrom/clonezilla-live-1.2.1-39.iso"
#CDROM="/kdchome/john/software/install46.iso"
#KVM="/usr/bin/kvm" # <--------- 0.10.0 which from debian kvm 0.85 package
KVM="/opt/kvm/bin/qemu-system-x86_64 -L /opt/kvm/share/qemu/" #
<--------- 0.10.50 which from kvm-0.87.tar.gz source code
USERID="$(whoami)"
PID="./pid.log"
iface="$(sudo /usr/sbin/tunctl -t tap${NUM} -b -u ${USERID})"

${KVM} -hda ${IMG} \
-net nic,vlan=${NUM},model=e1000,macaddr=00:AA:BB:CC:DD:0${NUM} \
-net
tap,vlan=${NUM},ifname="${iface}",script=/etc/kvm/kvm-ifup,downscript=/etc/kvm/kvm-ifdown
\
-localtime \
-usb -usbdevice tablet \
-k en-us -monitor stdio \
-soundhw all \
-cdrom ${CDROM} \
-m 1024 -vga cirrus -boot d $@


sleep 3
sudo /usr/sbin/tunctl -d ${iface}
exit $?