qemu JSON usage?

[afaas]

Hello,

Am trying to understand the usage of JSON blocks when launching qemu, for example in the documentation here:

qemu-system-x86_64 'json:{"driver":"qcow2",
                          "file":{"driver":"gluster",
                                   "volume":"testvol","path":"a.img",
                                   "debug":9,"logfile":"/var/log/qemu-gluster.log",
                                   "server":[{"type":"tcp","host":"1.2.3.4","port":24007},
                                             {"type":"unix","socket":"/var/run/glusterd.socket"}]}}'

Is the JSON QMP compatible configuration? Can you mix these json blocks and non-json config? Is the spec for what can be set in JSON defined in the QMP Reference Manual? How do I know when I can use json blocks for this type of configuration?

Best,
Afaas