Subject: Re: More Device Properties
To: None <firstname.lastname@example.org>
From: Chris G. Demetriou <email@example.com>
Date: 02/14/2001 16:15:56
> I think probably the right thing is:
> * when attaching, copy, and
> * let the parent be responsible for marking propdev immutable
> or not (and, of course, destroying it).
> That way, you can do whatever you want, and there are no real
> Sounds reasonable right now, but if we separate out the
> `struct device' from the softc then the propdev is transformed
> into the real device at attach time.
I'd still say, in that case, you just make a new one. I think it'd
simplify the code paths.
After all, for a sane interface, the caller still needs to
destroy/free the 'propdev' when it's done with it...
So, like everything else, just make a copy. 8-)
> Yeah, I originally thought it would be too much work but now
> it seems to be the only really clean solution. Seems a bit
> much for 1.6.
> It would break *EVERYTHING*. How do we migrate
> there? We could have devices that use `aux' have monolithic
> device structures and the others use a separate softc, but
> that would have to be based on the parent bus which registers
> the properties and preclude devices that can attach to both
Right, so, I think you basically need to do something like:
(1) keep passing in the 'aux' for backward compat. until you know
everything is dead.
(2) as busses are converted, attachments can be converted and/or
pointed to new common property-based match/attach rtns.
You may want to keep separate cfattach structs for a Long Time.
I think the real trick is, setting up some macros, etc., so that
cfattach, etc., can be done in a sane way, without need for touching
all the drivers N times. I.e. do the thing with a hackishly-passed
4th arg for now, but convert things to use macros/types over time to
declare cfattach & their fns, etc., so that after a while you can just
flip a switch in config.h...