<qemu:commandline> ignored ?

Hi guys. I have a domain definition with this: ...   <qemu:commandline>     <qemu:arg value='-fw_cfg'/>     <qemu:arg value='name=opt/com.coreos/config,file=/00-VMs/oshift1node.ign'/>   </qemu:commandline> </domain> at the bottom of xml. 'virsh' creates domain a okey but in VM I do not see ignition happened - it's fedora coreos - and when I dumpxml running domain, then indeed those bits, show above, are not there. I'd grateful for any/all thoughts shared on - what is not/happening there. Is there something else which is a prerequisite to 'qemu:commandline' but if yes and I'm missing those, why would not then 'virsh' and/or 'virtqemud' say something? many thanks, L.