[libvirt-users] pci slot increases after several times interface attach and detach

hi, I have a question about interface hotplug. I attach and detach interface from vm for several times. I find the pci slot of interface increases in live xml while keep unchanged in config xml. Here is my test script and result: Test Script: #!/bin/bash VM=ub1504b print_xml() { echo "$* : ========inactive===========" virsh dumpxml --inactive $VM |grep -A 20 "<interface" |grep "mac\|slot" echo "$* : ======== active===========" virsh dumpxml $VM |grep -A 20 "<interface" |grep "mac\|slot" } print_xml begin_ virsh attach-device --config --live $VM if1.xml print_xml attach virsh detach-device --config --live $VM if1.xml print_xml detach Result: begin_ : ========inactive=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> begin_ : ======== active=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> Device attached successfully attach : ========inactive=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> <mac address='0c:da:11:11:11:11'/> <address type='pci' domain='0x0000' bus='0x00' slot='*0x0c*' function='0x0'/> attach : ======== active=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> <mac address='0c:da:11:11:11:11'/> <address type='pci' domain='0x0000' bus='0x00' slot='*0x0d*' function='0x0'/> Device detached successfully detach : ========inactive=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> detach : ======== active=========== <mac address='0c:da:41:1e:02:9c'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> When execute the script for more than 1 times, You can see the pci slot of attached interface in live xml differs from the one in config xml. Is this intentional or a bug ? If not a bug, why?