[libvirt] Node devices?

[Ed Swierk]

After staring at the code implementing node devices in libvirt, I have
decided that they're really neat, but I have no idea what they are for
or how to use them.

Reading the API docs and searching libvir-list didn't help much, and
the user documentation (http://libvirt.org/archnode.html and
http://libvirt.org/formatnode.html) is a bit, err, high-level.

Can someone enlighten me?

--Ed