Boot VM from a zvol using qemu and nvmm?

[Jeff Rizzo <riz%tastylime.net@localhost>]

I've got a couple VMs running on a NetBSD-10 system under NVMM, 
following the stuff outlined here: 
https://www.netbsd.org/docs/guide/en/chap-virt.html - and it works 
pretty well; the disks are .qcow2 .


However, I'm wondering if it's possible to use a ZVOL as the disk 
instead - the primary motivation here is that I'd like to move a VM from 
another system (FreeBSD, as "TrueNAS"), and the easiest way to get the 
data over is to zfs send the zvol.  However, a naive setting of

-drive file=/dev/zvol/rdsk/tank/volumes/my-zvol

in place of what (on my other VMs) is

-drive file=/tank/volumes/my-disk.qcow2


Doesn't seem to work, or at least qemu doesn't recognize it as having a 
bootable image.

Should this work? More specifically, can I get this to work relatively 
easily, or would I be better off just using a qcow2 image for this disk 
and installing a fresh system instead of trying to migrate?

Thanks,

+j

--
Jeff Rizzo
riz%tastylime.net@localhost
+1 415 823 1847