https://bugzilla.redhat.com/show_bug.cgi?id=1217444 VMware guests can use either BIOS or UEFI firmware. VMware itself exposes this information in the VMX file and it's available to the ESX driver in libvirt. virt-v2v wants to consume this information. Unfortunately after a few years and iterations we've not come up with an acceptable patch to expose “has UEFI” in the libvirt XML. (Latest patch was: https://www.redhat.com/archives/libvir-list/2016-October/msg00045.html ) Could we instead add a temporary addition to the XML generated by the ESX driver? I'm thinking something like the existing <vmware:moref> and <vmware:datacenterpath> fields: <domain type='vmware' xmlns:vmware='http://libvirt.org/schemas/domain/vmware/1.0'> <name>Fedora</name> ... <vmware:datacenterpath>ha-datacenter</vmware:datacenterpath> <vmware:moref>2</vmware:moref> <vmware:firmware>uefi</vmware:firmware> <!-- "bios" or "uefi" --> </domain> This field would be informational, ie. the ESX driver would create it but not read it when creating new VMs. This would solve our immediate problem in virt-v2v and is pretty simple to implement. Also it doesn't close off any future general solution. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/