[libvirt] using disk devices with mixed bus types (ide and virtio)

Hello, While using multiple disk devices with different bus types (ide and virtio) I noticed that the order of disks is handled in a special way. The disk device which was defined as the first item will not be the first entry in the system xml file. e.g. if I define a virtio device (which is supposed to be the boot device) this would be added after all the ide devices. So it's not possible to boot from a virtio device even if I have defined other ide devices since qemu flags the first device as boot device. Is there a special reason why the disks are sorted by type (first all ide and then virtio) because that's prevents from booting virtio devices. Thanks. Mit freundlichen Grüßen / Kind regards Ingo Tuchscherer