Hello,

> I suppose worst case I could give foo a new function
> foo_register_extended_if(...) and the parent drivers that support
> the new interface could call it after attachment, supplying the
> additional method. I could make that work right away without having
> to understand autoconfiguration better than I do, but is there a
> less kludgey solution?

Either this, or memset() foo_hw_if to zero in all drivers before
filling it, or include an ioctl-like function through which you
can "tunnel" new methods as they appear.

I think each of these approaches has precedents in NetBSD code.

	-- Jachym Holecek