FreeBSD bhyve guest does not start anymore

[Andrea Venturoli]

Hello.

I've asked about this in the past (around January) and somehow I got 
some suggestions.
Either that helped me solve the problem, but now it's back, or I never 
rebooted the host and simply forgot about it.
In any case...

Due to a 12.x specific bug, I run a 11.3 guest using vm-bhyve.
This is its config:
> loader="bhyveload"
> cpu=1
> memory=512M
> network0_type="virtio-net"
> network0_switch="public"
> disk0_type="virtio-blk"
> disk0_name="disk0"
> disk0_dev="sparse-zvol"
> uuid="..."
> network0_mac="..."

When I start it, the guest boots, but hangs after the kernel is loaded with:
> 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/cd0 ro
>           (which is equivalent to: mount -t cd9660 -o ro /dev/cd0 /)
> 
>   ?               List valid disk boot devices
>   .               Yield 1 second (for background tasks)
>   <empty line>    Abort manual input
> 
> mountroot> 

Then, if I just type "ufs:/dev/vtbd0a" it will start correctly.

As can be seen from the config: the host is running with ZFS, the guest 
only has a zvol disk and from its POV there's only one partition (UFS).

Volmode is set to dev (as was suggested in January):
>  zfs get volmode zroot/vm/f11b/disk0
> NAME                 PROPERTY  VALUE    SOURCE
> zroot/vm/f11b/disk0  volmode   dev      local

Any other hint?

  bye & Thanks
	av.