[libvirt-users] why attach-disk can't be effective when the guest is booting

Hi, When i use "virsh attach-device rhel disk.xml" when the guest is booting,then i can't find the disk in the guest after booting.But i can find it by "virsh domblklist rhel",and when i want to detach it from the guest and use "virsh detach-disk rhel vdb", i still can find the disk by "virsh domblklist rhel" The disk.xml is like: <disk type="file" device="disk"> <driver name='qemu' type='raw' cache='none'/> <source file="/var/lib/libvirt/images/foo.img"/> <target dev="vdb" bus="virtio"/> </disk> Libvirt-release is 5.0.0.4 and the qemu-kvm release is 3.1.0 So i want to know why it failed to attach-disk when booting,and why we design in this way.Maybe it's better to return failure if we can't use it like this.