I've not gotten any bites from my posting on the xen-devel mailing list. Here is the only one to-date:

https://lists.xen.org/archives/html/xen-devel/2017-04/msg01069.html

From that email, there needs to be some hypervisor messages.

Does anyone know how to produce the hypervisor messages? I've already removed the rhgb and quiet options from the boot.

Thanks

PJ