[libvirt][qemu] Ho to get a 'boot=on' parameter to appear on kvm command line

Hi, all. Can someone tell me how to get boot=on parameter to appear on my kvm cmdline? I define domain with the following xml <domain type="kvm"> <name>kvm-1</name> <memory>524288</memory> <vcpu>1</vcpu> <os> <type arch="x86_64" machine="pc">hvm</type> <boot dev="hd"/> </os> <devices> <emulator>/usr/bin/kvm</emulator> <graphics type="vnc" port="-1"/> <disk device="disk" type="file"> <source file="test.img"/> <target dev="sda"/> </disk> <interface type="bridge"> <source bridge="breth0"/> </interface> </devices> </domain> and get /usr/bin/kvm -S -M pc -m 512 -smp 1 -name kvm-1 -uuid b462e575-4044-146c-193a-9a70523b4258 -monitor pty -no-acpi -boot c -drive file=test.img,if=scsi,index=0 -net nic,macaddr=52:54:00:09:9b:19,vlan=0 -net tap,fd=15,vlan=0 -serial none -parallel none -usb But I want to get -drive file=test.img,if=scsi,index=0,boot=on instead.