uart change

[Warner Losh]

From: Marcel Moolenaar <marcel at xcllnt.net>
Subject: Re: PERFORCE change 88102 for review
Date: Mon, 12 Dec 2005 16:45:32 -0800

> 
> On Dec 12, 2005, at 9:58 PM, Warner Losh wrote:
> 
> > http://perforce.freebsd.org/chv.cgi?CH=88102
> >
> > Change 88102 by imp at imp_Speedy on 2005/12/12 21:58:35
> >
> > 	Make uart_subr not depend on ns8250.o
> 
> This is not such a good change. As the comment says in uart_subr.c, it's
> just a default. There's nothing PC specific about it. It's the the most
> common case and therefore a sensible default.
> 
> Now, if it makes sense to have MD specific defaults and not MI defaults,
> then it makes sense to have ALL the defaults set in MD code and none in
> MI code (or if they are set in MI code, they should be set before MD
> defaults can be set to override the MI defaults).
> 
> What really needs to be done is add support for the DT tag, so that you
> can set the device type in the environment....

This is a good change.

The problem is that it forces you to link in uart_dev_ns8250.o, even
if your platform doesn't have one of those.  That's the reason that I
moved it out of there.  It has nothing to do with what the default
device should be, but rather the linkage dependency it creates

Warner