[Libguestfs] How to debug supermin5 issue?

Hi, Rich: I met a supermin issue on CentOS 7.1: supermin: version: 5.1.10 supermin: rpm: detected RPM version 4.11 supermin: package handler: fedora/rpm supermin: acquiring lock on /root/test/aaa/lock supermin: build: /usr/lib64/guestfs/supermin.d supermin: build: visiting /usr/lib64/guestfs/supermin.d/base.tar.gz type gzip base image (tar) supermin: build: visiting /usr/lib64/guestfs/supermin.d/daemon.tar.gz type gzip base image (tar) supermin: build: visiting /usr/lib64/guestfs/supermin.d/excludefiles type uncompressed excludefiles supermin: build: visiting /usr/lib64/guestfs/supermin.d/hostfiles type uncompressed hostfiles supermin: build: visiting /usr/lib64/guestfs/supermin.d/init.tar.gz type gzip base image (tar) supermin: build: visiting /usr/lib64/guestfs/supermin.d/packages type uncompressed packages supermin: build: visiting /usr/lib64/guestfs/supermin.d/udev-rules.tar.gz type gzip base image (tar) supermin: build: 185 packages, including dependencies supermin: build: 30676 files supermin: build: 17495 files, after removing unreadable files supermin: build: 8834 files, after matching excludefiles supermin: build: 8840 files, after adding hostfiles supermin: build: 8870 files, after munging supermin: kernel: picked kernel vmlinuz-3.10.0-229.el7.x86_64 supermin: kernel: picked modules path /lib/modules/3.10.0-229.el7.x86_64 supermin: kernel: kernel_version 3.10.0-229.el7.x86_64 supermin: kernel: modules /lib/modules/3.10.0-229.el7.x86_64 supermin: ext2: creating empty ext2 filesystem '/root/test/aaa.8v6mujxm/root' supermin: ext2: populating from base image supermin: ext2: copying files from host filesystem supermin: ext2: copying kernel modules supermin: ext2: creating minimal initrd '/root/test/aaa.8v6mujxm/initrd' supermin: ext2: wrote 0 modules to minimal initrd ^ | It seam that supermin failed to write modules into initrd. But it works fine on another centos 7.1 machine. Could you please give me some hints on how to debug this kind of issue? Thanks in advance. Regards, - Chen