other: 0.963
device: 0.921
semantic: 0.805
graphic: 0.661
debug: 0.566
boot: 0.521
network: 0.503
performance: 0.398
files: 0.297
socket: 0.270
PID: 0.248
vnc: 0.243
KVM: 0.237
permissions: 0.216

-blockdev option missing host_device documenation and command line help support
Additional information:
We recommend -blockdev in the documentation as the preferred way to configure storage backends but the online help isn't useful. We also seem to be missing information for some of the blockdev drivers, for example host_device.