[libvirt] Why virsh domxml-to-native qemu-argv changes PCI slot number

Hi, I have bridge type interface defined with slot 3 - <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> but after running virsh domxml-to-native qemu-argv I get slot 2- -netdev tap,fd=21,id=hostnet0 -device e1000,netdev=hostnet0,id=net0,mac=f2:ff:ff:ff:ff:07,bus=pci.0,addr=0x2 Any idea why it's happen and how to keep the slot number? Libvirt version is 4.5.0 here is the full domain XML - <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'> <name>vm1</name> <uuid>dbad303e-fc1b-454e-8861-712bf1766a64</uuid> <memory unit='KiB'>4194304</memory> <currentMemory unit='KiB'>4194304</currentMemory> <vcpu placement='static'>1</vcpu> <os> <type arch='x86_64' machine='pc-i440fx-2.12'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> </features> <cpu mode='custom' match='exact' check='partial'> <model fallback='allow'>SandyBridge-IBRS</model> </cpu> <clock offset='utc'> <timer name='rtc' tickpolicy='catchup'/> <timer name='pit' tickpolicy='delay'/> <timer name='hpet' present='no'/> </clock> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <pm> <suspend-to-mem enabled='no'/> <suspend-to-disk enabled='no'/> </pm> <devices> <emulator>/qemu/x86_64-softmmu/qemu-system-x86_64</emulator> <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/vm.img'/> <target dev='hda' bus='ide'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <controller type='usb' index='0' model='ich9-ehci1'> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x7'/> </controller> <controller type='usb' index='0' model='ich9-uhci1'> <master startport='0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0' multifunction='on'/> </controller> <controller type='usb' index='0' model='ich9-uhci2'> <master startport='2'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x1'/> </controller> <controller type='usb' index='0' model='ich9-uhci3'> <master startport='4'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x2'/> </controller> <controller type='ide' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <controller type='pci' index='0' model='pci-root'/> <interface type='bridge'> <mac address='f2:ff:ff:ff:ff:07'/> <source bridge='br0:'/> <model type='e1000'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='tcp'> <source mode='bind' host='10.210.27.119' service='9999'/> <protocol type='telnet'/> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> </serial> <console type='tcp'> <source mode='bind' host='10.210.27.119' service='9999'/> <protocol type='telnet'/> <target type='serial' port='0'/> </console> <input type='mouse' bus='ps2'/> <input type='keyboard' bus='ps2'/> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </memballoon> </devices> <qemu:commandline> <qemu:env name='CONFIG_FILE' value='/opt/cfg/qemu.cfg'/> </qemu:commandline> </domain> Thanks, Tal