I'm able to add (>add-ro image) a newly created image (created with vmbuilder) using the guestfish shell, but unable to run it.  I appear to be getting kernel panics when doing so.  In trying to debug the issue, I noticed that libguestfs-test-tool also fails with a kernel panic due to sync errors.  I had previously suspected an issue with the kernel file permissions but this was resolved by allowing read access.