Comment 2 for bug 1715686

So, in order for me to work, i needed to add lvm2 on the dracut image, using dracut-regenerate element:
http://git.openstack.org/cgit/openstack/diskimage-builder/tree/diskimage_builder/elements/dracut-regenerate

If not, as the volume support is not found on the ramdisk, is not able to detect root.