Description of problem:

I'm experimenting with libvirt's nbd feature, using the
'unix' transport.  However it doesn't seem to work.

The original XML is:

<?xml version="1.0"?>
<domain type="kvm" xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0">
  <name>guestfs-3ujzjfcpypadwmna</name>
  <memory unit="MiB">500</memory>
  <currentMemory unit="MiB">500</currentMemory>
  <vcpu>1</vcpu>
  <clock offset="utc"/>
  <os>
    <type>hvm</type>
    <kernel>/home/rjones/d/libguestfs/tmp/.guestfs-1000/kernel.25906</kernel>
    <initrd>/home/rjones/d/libguestfs/tmp/.guestfs-1000/initrd.25906</initrd>
    <cmdline>panic=1 console=ttyS0 udevtimeout=600 no_timer_check acpi=off printk.time=1 cgroup_disable=memory root=/dev/sdb selinux=0 guestfs_verbose=1 TERM=xterm-256color</cmdline>
  </os>
  <on_reboot>destroy</on_reboot>
  <devices>
    <controller type="scsi" index="0" model="virtio-scsi"/>
    <disk device="disk" type="network">
      <source protocol="nbd">
        <host transport="unix" socket="/home/rjones/d/libguestfs/tests/nbd/unix.sock"/>
      </source>
      <target dev="sda" bus="scsi"/>
      <driver name="qemu" type="raw"/>
      <address type="drive" controller="0" bus="0" target="0" unit="0"/>
    </disk>
    <disk type="file" device="disk">
      <source file="/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/snapshot1"/>
      <target dev="sdb" bus="scsi"/>
      <driver name="qemu" type="qcow2" cache="unsafe"/>
      <address type="drive" controller="0" bus="0" target="1" unit="0"/>
      <shareable/>
    </disk>
    <serial type="unix">
      <source mode="connect" path="/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/console.sock"/>
      <target port="0"/>
    </serial>
    <channel type="unix">
      <source mode="connect" path="/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/guestfsd.sock"/>
      <target type="virtio" name="org.libguestfs.channel.0"/>
    </channel>
  </devices>
  <qemu:commandline>
    <qemu:env name="TMPDIR" value="/home/rjones/d/libguestfs/tmp"/>
  </qemu:commandline>
</domain>

The generated command line + other logs is:

LC_ALL=C LD_LIBRARY_PATH=/home/rjones/d/libguestfs/ruby/ext/guestfs:/home/rjones/d/libguestfs/src/.libs:/home/rjones/d/libguestfs/gobject/.libs PATH=/home/rjones/d/libguestfs/erlang:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/home/rjones/.local/bin:/home/rjones/bin HOME=/home/rjones USER=rjones LOGNAME=rjones TMPDIR=/home/rjones/d/libguestfs/tmp /usr/bin/qemu-kvm -name guestfs-3ujzjfcpypadwmna -S -M pc-i440fx-1.4 -m 500 -smp 1,sockets=1,cores=1,threads=1 -uuid 5505655c-f1b7-7fbc-3c63-b899d9c3d74c -nographic -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/home/rjones/.config/libvirt/qemu/lib/guestfs-3ujzjfcpypadwmna.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-reboot -no-shutdown -no-acpi -kernel /home/rjones/d/libguestfs/tmp/.guestfs-1000/kernel.25906 -initrd /home/rjones/d/libguestfs/tmp/.guestfs-1000/initrd.25906 -append panic=1 console=ttyS0 udevtimeout=600 no_timer_check acpi=off printk.time=1 cgroup_disable=memory root=/dev/sdb selinux=0 guestfs_verbose=1 TERM=xterm-256color -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x3 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 -drive file=nbd:(null):(null),if=none,id=drive-scsi0-0-0-0,format=raw -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1 -drive file=/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/snapshot1,if=none,id=drive-scsi0-0-1-0,format=qcow2,cache=unsafe -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=1,lun=0,drive=drive-scsi0-0-1-0,id=scsi0-0-1-0 -chardev socket,id=charserial0,path=/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/console.sock -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,path=/home/rjones/d/libguestfs/tmp/libguestfs5XonVS/guestfsd.sock -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.libguestfs.channel.0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
Domain id=4 is tainted: custom-argv
qemu-system-x86_64: -drive file=nbd:(null):(null),if=none,id=drive-scsi0-0-0-0,format=raw: address resolution failed for (null):(null): Servname not supported for ai_socktype
qemu: terminating on signal 15 from pid 25917
2013-03-18 17:46:10.341+0000: shutting down

Version-Release number of selected component (if applicable):

libvirt-daemon-1.0.3-1.fc20.x86_64

How reproducible:

100%