diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng
index e819544e2b..9121da3661 100644
--- a/docs/schemas/domain.rng
+++ b/docs/schemas/domain.rng
@@ -1470,6 +1470,11 @@
         <ref name="driveBus"/>
       </attribute>
     </optional>
+    <optional>
+      <attribute name="port">
+        <ref name="driveUnit"/>
+      </attribute>
+    </optional>
   </define>
   <!--
       Devices attached to a domain.
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args
new file mode 100644
index 0000000000..e59d944099
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.args
@@ -0,0 +1 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -device virtio-serial-pci,id=virtio-serial0,max_ports=16,vectors=4,bus=pci.0,addr=0x4 -device virtio-serial-pci,id=virtio-serial1,bus=pci.0,addr=0xa -device virtio-serial-pci,id=virtio-serial2,bus=pci.0,addr=0x5 -hda /dev/HostVG/QEMUGuest1 -chardev pty,id=channel0 -device virtserialport,bus=virtio-serial0.0,nr=0,chardev=channel0,name=org.linux-kvm.port.0 -chardev pty,id=channel1 -device virtserialport,bus=virtio-serial1.0,nr=0,chardev=channel1,name=org.linux-kvm.port.foo -chardev pty,id=channel2 -device virtserialport,bus=virtio-serial1.0,nr=3,chardev=channel2,name=org.linux-kvm.port.bar -chardev pty,id=channel3 -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=channel3,name=org.linux-kvm.port.wizz -chardev pty,id=channel4 -device virtserialport,bus=virtio-serial1.0,nr=4,chardev=channel4,name=org.linux-kvm.port.ooh -chardev pty,id=channel5 -device virtserialport,bus=virtio-serial2.0,nr=0,chardev=channel5,name=org.linux-kvm.port.lla -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.xml b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.xml
new file mode 100644
index 0000000000..6e3458f1de
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-auto.xml
@@ -0,0 +1,51 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory>219200</memory>
+  <currentMemory>219200</currentMemory>
+  <vcpu cpuset='1-4,8-20,525'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+    <controller type='virtio-serial' index='0' ports='16' vectors='4'/>
+    <controller type='virtio-serial' index='1'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
+    </controller>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.0'/>
+    </channel>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.foo'/>
+      <address type='virtio-serial' controller='1' bus='0'/>
+    </channel>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.bar'/>
+      <address type='virtio-serial' controller='1' bus='0' port='3'/>
+    </channel>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.wizz'/>
+      <address type='virtio-serial' controller='0' bus='0'/>
+    </channel>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.ooh'/>
+      <address type='virtio-serial' controller='1' bus='0'/>
+    </channel>
+    <channel type='pty'>
+      <target type='virtio' name='org.linux-kvm.port.lla'/>
+      <address type='virtio-serial' controller='2' bus='0'/>
+    </channel>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args
index e59d944099..203468eef6 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.args
@@ -1 +1 @@
-LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -device virtio-serial-pci,id=virtio-serial0,max_ports=16,vectors=4,bus=pci.0,addr=0x4 -device virtio-serial-pci,id=virtio-serial1,bus=pci.0,addr=0xa -device virtio-serial-pci,id=virtio-serial2,bus=pci.0,addr=0x5 -hda /dev/HostVG/QEMUGuest1 -chardev pty,id=channel0 -device virtserialport,bus=virtio-serial0.0,nr=0,chardev=channel0,name=org.linux-kvm.port.0 -chardev pty,id=channel1 -device virtserialport,bus=virtio-serial1.0,nr=0,chardev=channel1,name=org.linux-kvm.port.foo -chardev pty,id=channel2 -device virtserialport,bus=virtio-serial1.0,nr=3,chardev=channel2,name=org.linux-kvm.port.bar -chardev pty,id=channel3 -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=channel3,name=org.linux-kvm.port.wizz -chardev pty,id=channel4 -device virtserialport,bus=virtio-serial1.0,nr=4,chardev=channel4,name=org.linux-kvm.port.ooh -chardev pty,id=channel5 -device virtserialport,bus=virtio-serial2.0,nr=0,chardev=channel5,name=org.linux-kvm.port.lla -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -nodefaults -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -device virtio-serial-pci,id=virtio-serial1,bus=pci.0,addr=0xa -hda /dev/HostVG/QEMUGuest1 -chardev pty,id=channel0 -device virtserialport,bus=virtio-serial1.0,nr=3,chardev=channel0,name=org.linux-kvm.port.foo -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml
index 6e3458f1de..e597c407e4 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml
+++ b/tests/qemuxml2argvdata/qemuxml2argv-channel-virtio.xml
@@ -20,32 +20,12 @@
       <address type='drive' controller='0' bus='0' unit='0'/>
     </disk>
     <controller type='ide' index='0'/>
-    <controller type='virtio-serial' index='0' ports='16' vectors='4'/>
     <controller type='virtio-serial' index='1'>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
     </controller>
-    <channel type='pty'>
-      <target type='virtio' name='org.linux-kvm.port.0'/>
-    </channel>
     <channel type='pty'>
       <target type='virtio' name='org.linux-kvm.port.foo'/>
-      <address type='virtio-serial' controller='1' bus='0'/>
-    </channel>
-    <channel type='pty'>
-      <target type='virtio' name='org.linux-kvm.port.bar'/>
       <address type='virtio-serial' controller='1' bus='0' port='3'/>
     </channel>
-    <channel type='pty'>
-      <target type='virtio' name='org.linux-kvm.port.wizz'/>
-      <address type='virtio-serial' controller='0' bus='0'/>
-    </channel>
-    <channel type='pty'>
-      <target type='virtio' name='org.linux-kvm.port.ooh'/>
-      <address type='virtio-serial' controller='1' bus='0'/>
-    </channel>
-    <channel type='pty'>
-      <target type='virtio' name='org.linux-kvm.port.lla'/>
-      <address type='virtio-serial' controller='2' bus='0'/>
-    </channel>
   </devices>
 </domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 9e4d5bf963..ca0313139b 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -330,6 +330,7 @@ mymain(int argc, char **argv)
 
     DO_TEST("channel-guestfwd", QEMUD_CMD_FLAG_CHARDEV|QEMUD_CMD_FLAG_DEVICE);
     DO_TEST("channel-virtio", QEMUD_CMD_FLAG_DEVICE);
+    DO_TEST("channel-virtio-auto", QEMUD_CMD_FLAG_DEVICE);
 
     DO_TEST("watchdog", 0);
     DO_TEST("watchdog-device", QEMUD_CMD_FLAG_DEVICE);