> If I'm not mistaken, don't we have some potential circular references?

You're not mistaken.

> i.e.
> 	pci* at ppb? bus ?
> and
> 	ppb* at pci? dev ? function ?

Or
	xbox* at sbus? slot ? offset ?
	sbus* at xbox?

> That could get hairy.

Indeed it could.  Note that Luke said he'd started on "no device", but
wasn't expecting it to be nearly as easy; I'd hazard a guess that
issues like this are why.

Even if it doesn't work for devices, "no" is still valuable.

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