+@item -object colo-compare,id=@var{id},primary_in=@var{chardevid},secondary_in=@var{chardevid},
+outdev=@var{chardevid}
+
+Colo-compare gets packet from primary_in@var{chardevid} and secondary_in@var{chardevid}, than compare primary packet with
+secondary packet. If the packets are same, we will output primary
+packet to outdev@var{chardevid}, else we will notify colo-frame
+do checkpoint and send primary packet to outdev@var{chardevid}.
+
+we must use it with the help of filter-mirror and filter-redirector.
+
+@example
+
+primary:
+-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
+-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
+-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
+-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
+-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
+-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
+-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
+-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
+-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
+-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
+-object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
+-object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0
+
+secondary:
+-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
+-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
+-chardev socket,id=red0,host=3.3.3.3,port=9003
+-chardev socket,id=red1,host=3.3.3.3,port=9004
+-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
+-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
+
+@end example
+
+If you want to know the detail of above command line, you can read
+the colo-compare git log.
+
+@item -object cryptodev-backend-builtin,id=@var{id}[,queues=@var{queues}]
+
+Creates a cryptodev backend which executes crypto opreation from
+the QEMU cipher APIS. The @var{id} parameter is
+a unique ID that will be used to reference this cryptodev backend from
+the @option{virtio-crypto} device. The @var{queues} parameter is optional,
+which specify the queue number of cryptodev backend, the default of
+@var{queues} is 1.
+
+@example
+
+ # qemu-system-x86_64 \
+ [...] \
+ -object cryptodev-backend-builtin,id=cryptodev0 \
+ -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
+ [...]
+@end example
+