Subject: Re: Device Properties: The Next Generation
To: None <cgd@sibyte.com, eeh@netbsd.org>
From: None <eeh@netbsd.org>
List: tech-kern
Date: 02/16/2001 23:50:08
	eeh@netbsd.org writes:
	> 	I think doing inheritance based on the property, rather than the type
	> 	of call to lookup, would probably address most of my concerns that
	> 	would require "white-outs".
	> 
	> Limiting inheritance to `x' number of levels does not work.  A bus
	> driver cannot know how many levels of bridges are between it and the
	> end device.  You would need a way to `extend' properties down another
	> level, which is the equivalent of just duplicating them on each level.

	Ahh, but, in that case, the thing doing the extending _is_ effectively
	another bus bridge.  It may not act like that in hardware really, but
	in terms of the configuration code, it's parent.

	It's duplicating them at very bus bridge (once per 'level' if that's
	the way you want to think about it), which should be significantly
	less duplication than if done at every device.  (log N vs N.)


	I'm still thinking that limiting inheritance to 'x' number of levels
	is the best thought so far for doing inheritance sanely...

I still don't get it.  Could you give an example where limiting
a property to `x' levels below this node would be useful?

Eduardo