Getting enlightened drivers to load only when Hyper-V (or Azure) is detected

[Larry Melia (Insight Global)]

We're preparing our Hyper-V, enlightened drivers to be included in the CURRENT build, but need some help with the loader configuration. The drivers should only load or remain resident when Hyper-V is present. On Linux, the installer program was modified to detect the presence of Hyper-V/Azure, and only then are the Hyper-V drivers installed (starting with the VM Bus driver). What's the best way to do this on FreeBSD? Any help would be greatly appreciated!
Thanks in advance!
Larry Melia
Enlightened driver team for FreeBSD on Hyper-V