dhcp nginx rumprun on xen

rumprun xen -di \
    -N rumpy \
    -I t,xenif,'bridge=br0,mac=c0:ff:ee:c0:ff:ee' \
    -W t,inet,dhcp \
    -b images/stubetc.iso,/etc \
    -b images/data.iso,/data \
    -- nginx.bin -c /data/conf/nginx.conf
!!!
!!! NOTE: rumprun is experimental. syntax may change in the future
!!!

  start_info: 0x747000(VA)
    nr_pages: 0x4000
  shared_inf: 0x7f2cc000(MA)
     pt_base: 0x74a000(VA)
nr_pt_frames: 0x7
    mfn_list: 0x727000(VA)
   mod_start: 0x0(VA)
     mod_len: 0
       flags: 0x0
    cmd_line:
  stack:      0x6884e0-0x7084e0
MM: Init
      _text: 0x0(VA)
     _etext: 0x380224(VA)
   _erodata: 0x4d8000(VA)
     _edata: 0x504120(VA)
stack start: 0x6884e0(VA)
       _end: 0x726440(VA)
  start_pfn: 754
    max_pfn: 4000
Mapping memory range 0x800000 - 0x4000000
setting 0x0-0x4d8000 readonly
skipped 0x1000
MM: Initialise page allocator for 770000(770000)-4000000(4000000)
MM: done
Demand map pfns at 4001000-2004001000.
Initialising timer interface
Initialising console ... done.
gnttab_table mapped at 0x4001000.
xenbus initialised on irq 1 mfn 0x28928
Failed to read device/pci/0/backend-id.
no backend
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 7.99.17 (RUMP-ROAST)
total memory = 28896 KB
timecounter: Timecounters tick every 10.000 msec
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
cpu0 at thinair0: rump virtual cpu
root file system type: rumpfs
kern.module.path=/stand/amd64/7.99.17/modules
mainbus0 (root)
timecounter: Timecounter "bmktc" frequency 1000000000 Hz quality 100
mounted tmpfs on /tmp
net TX ring size 256
net RX ring size 256
netfront: node=device/vif/0 backend=/local/domain/0/backend/vif/19/0
netfront: MAC c0:ff:ee:c0:ff:ee
xenif0: Ethernet address c0:ff:ee:c0:ff:ee
dhcp get: timed out waiting for response.
dhcp: didn't receive ack