[Libguestfs] vmdk support by libguestfs in RHEL and upstream

Hi all, As we are doing plan for testing libguestfs, I have a question about vmdk support for libguestfs. In Fedora 12, we can successfully manage a vmdk image via guestfish(add -> run -> mkfs -> mount -> ...). But in RHEL6, for qemu-kvm can not boot with a vmdk image, libguestfs can not manage vmdk either. So is it true that vmdk is only supported by upstream libguestfs but not the version in RHEL6? Thanks. --Yufang