<devices>
     <emulator>/usr/lib/xen/bin/qemu-dm</emulator>
     <disk type="block" device="floppy">
-      <source dev="/dev/null"/>
+      <source dev="/dev/zero" startupPolicy="optional"/>
       <target dev="fda" bus="fdc"/>
       <boot order="5"/>
       <address type="drive" controller="0" bus="0" target="0" unit="0"/>
+      <readonly/>
     </disk>
     <disk type="file" device="disk">
       <source file="/tmp/foobar"/>

Domain 'test-for-virtxml' defined successfully.
Changes will take effect after the domain is fully powered off.