title: What can qemu's virtio-blk's drive parameter be set to
body: <p>I'm trying to start qemu with a virtio disk controller and it says:</p>
  
  <pre><code>qemu-system-x86_64 -S -gdb tcp::9000 --nographic --enable-kvm -cpu host -m 8192 -device virtio-blk-pci,drive=c,scsi=off -drive file=hard.disk,if=virtio,format=raw -fda floppy.img                                                           
  qemu-system-x86_64: -device virtio-blk-pci,drive=c,scsi=off: Property 'virtio-blk-device.drive' can't find value 'c'   
  </code></pre>
  
  <p>The reason I'm using the -device parameter is that I already tried just if=virtio on -drive but when I scanned the PCI devices no virtio block device showed up.</p>
  
  <p>I'm writing my own OS from scratch.</p>
  
  <p>How do I get this virtio PCI device to appear?</p>