Comment 1 for bug 1300861

It's worth noting that neither the original blueprint [1] or the commit message for the patch [2] that added this functionality mention any restrictions around image type, though the behaviour is understandable it should have been noted for documentation etc.

[1] https://blueprints.launchpad.net/nova/+spec/enable-libvirt-driver-to-read-kernel-command-line-from-glance-image
[2] https://review.openstack.org/#/c/65028/