   <devices>
     <emulator>/usr/lib/xen/bin/qemu-dm</emulator>
     <disk type="block" device="floppy">
-      <source dev="/dev/null"/>
       <target dev="fda" bus="fdc"/>
       <address type="drive" controller="0" bus="0" target="0" unit="0"/>
     </disk>

Domain 'test-many-devices' defined successfully.
Changes will take effect after the next domain shutdown.