DFly on Bhyve

[Chuck Musser]

My attempt to boot DragonFly in Bhyve using an ISO image is failing
partway through the process. The failure looks like this:

cd0 at ahci0 bus 0 target 0 lun 0
cd0: <BHYVE BHYVE DVD-ROM 001> Removable CD-ROM SCSI-0 device 
cd0: 600.000MB/s transfers
cd0: cd present [433760 x 2048 byte records]
no B_DEVMAGIC (bootdev=0)

Manual root filesystem specification:
  <fstype>:<device>  Specify root (e.g. ufs:da0s1a)
  ?                  List valid disk boot devices
  panic              Just panic
  abort              Abort manual input

mountroot> panic: Root mount failed, startup aborted.
cpuid = 0
Trace beginning at frame 0xffffffff81505cc0
panic() at panic+0x261 0xffffffff806025cb 
panic() at panic+0x261 0xffffffff806025cb 
kgetdiskbyname() at kgetdiskbyname+0x863 0xffffffff80674282 
mi_startup() at mi_startup+0xa7 0xffffffff805d0f13 
Debugger("panic")

I'm doing this by loosely following the FreeBSD Handbook's instructions
on how to use Bhyve. Their guide suggests that non-FreeBSD OSes are booted
with GRUB. I've create a GRUB "map" file that defines devices for the ISO
image and the image that will hold the "installed" system. Once GRUB is
started, I used the following commands to boot.

kfreebsd (cd0)/boot/kernel/kernel
boot

In the above output, what would help is being able to stop at the
mountroot prompt and seeing what devices are available. Is there
a way to do that or otherwise troubleshoot what's going on? It
seems like running Dfly under Bhyve is possible, given that it gets
partway through the boot process. But I'm probably missing GRUB
commands or maybe not passing needed arguments to the Dfly bootloader.

Anyone have experience with this?

Chuck