I use
QEMU emulator version 1.6.0, Copyright (c) 2003-2008 Fabrice Bellard
I don't give any networking options at the command line and it works
for me. I use 9front but I don't think it matters.

term% pci | grep net
0.3.0:    net  02.00.00 8086/100e  11 0:febc0000 131072 1:0000c041 64
term% cat '#l0/ether0/ifstats'
Good Packets Received: 161 0
Good Packets Transmitted: 94 0
Total Octets Received: 163085 0
Total Octets Transmitted: 9118 0
Total Packets Received: 161 0
Total Packets Transmitted: 94 0
lintr: 0 1
rintr: 96 96
tintr: 0 0
ixcs: 0 0 0
rdtr: 0
Ctrlext: 00000000
eeprom: 5452 1200 5634 0000 FFFF 0000 0000 0000
        3000 1000 6403 100E 8086 100E 8086 3040
        0008 2000 7E14 0048 1000 00D8 0000 2700
        6CC9 3150 0722 040B 0984 0000 C000 0706
        1008 0000 0F04 7FFF 4D01 FFFF FFFF FFFF
        FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
        0100 4000 121C FFFF FFFF FFFF FFFF FFFF
        FFFF FFFF FFFF FFFF FFFF FFFF FFFF 79AD
phy:    9140 794D 0141 0C20 01E1 01E0 FFFFFFFF FFFFFFFF
        FFFFFFFF 0F00 3C00 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF
        0B62 AC00 FFFFFFFF FFFFFFFF 0170 0000 FFFFFFFF FFFFFFFF
        FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF
term% ndb/query sys $sysname
ip=10.0.2.15 ipmask=255.255.255.0 ipgw=10.0.2.2 sys=cake dns=10.0.2.3
sys=cake ether=525400123456
term%



2014/1/7 Bakul Shah <bakul@bitblocks.com>
On Tue, 07 Jan 2014 22:16:02 GMT Yoann Padioleau <pad@fb.com> wrote:
> I've installed plan9 on a plan9.raw.img file via qemu and I'm able to boot =
> on it.
> How can I transfer files between plan9 and my host (I'm under macos)?
> I've followed http://plan9.bell-labs.com/wiki/plan9/installing_plan_9_on_qe=
> mu/index.html
> and run
>
>
> qemu -hda Plan9.qcow2.img -net nic -net user
>
> but from plan9 when I do
>
>  rc> ip/ping 10.0.2.2 nothing happens.

You can reuse your qcow image with virtualbox where this is
relatively easy to fix.