[libvirt-users] where is the libvirt.xml ?

Hi all: My OS is now Fedora16 , and the spice server is installed on it by rpms. Then I run 'qemu-kvm -hda /root/vaddsoft.img -m 512 -vga qxl -spice port=5930,disable-ticketing' , I want to find out where is the libvirt.xml for the command . Well , I mean that the libvirt.xml is genrated automatically, not by myself manually. Wish your help! Thanks a lot! -- Yours. suyi