bhyve fails to boot 9.1-RELEASE CD image

[Aryeh Friedman]

I get this when attempting to boot a 9.1-RELEASE ISO (amd/dvd1):


mountroot: waiting for device /dev/iso9660/FREEBSD_INSTALL ...
Mounting from cd9660:/dev/iso9660/FREEBSD_INSTALL failed with error 19.

Loader variables:
  vfs.root.mountfrom=cd9660:/dev/iso9660/FREEBSD_INSTALL
  vfs.root.mountfrom.options=ro

Manual root filesystem specification:
  <fstype>:<device> [options]
      Mount <device> using filesystem <fstype>
      and with the specified (optional) option list.

    eg. ufs:/dev/da0s1a
        zfs:tank
        cd9660:/dev/acd0 ro
          (which is equivalent to: mount -t cd9660 -o ro /dev/acd0 /)

  ?               List valid disk boot devices
  .               Yield 1 second (for background tasks)
  <empty line>    Abort manual input

mountroot> ?