From owner-freebsd-questions  Mon Mar 18 08:46:57 1996
Return-Path: owner-questions
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id IAA05062
          for questions-outgoing; Mon, 18 Mar 1996 08:46:57 -0800 (PST)
Received: from haywire.DIALix.COM (root@haywire.DIALix.COM [192.203.228.65])
          by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id IAA05053
          for <freebsd-questions@freebsd.org>; Mon, 18 Mar 1996 08:46:49 -0800 (PST)
Received: (from news@localhost) by haywire.DIALix.COM (8.7.4/8.6.12) id AAA05792 for freebsd-questions@freebsd.org; Tue, 19 Mar 1996 00:47:00 +0800 (WST)
X-Authentication-Warning: haywire.DIALix.COM: news set sender to usenet-request@haywire.dialix.com using -f
Received: from GATEWAY by haywire.DIALix.COM with netnews
	for freebsd-questions@freebsd.org (problems to: usenet@haywire.dialix.com)
To: freebsd-questions@freebsd.org
Date: 18 Mar 96 14:59:43 GMT
From: peter@jhome.DIALix.COM (Peter Wemm)
Message-ID: <peter.827161183@jhome.DIALix.COM>
Organization: DIALix Services, Perth, Australia.
References: <199603180022.KAA21384@genesis.atrad.adelaide.edu.au>, <Pine.BSF.3.91.960317221512.1180B-100000@Kryten.nina.com>
Subject: Re: KERNEL
Sender: owner-questions@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

frankd@yoda.fdt.net (Frank Seltzer) writes:

>> Please post it again, and make sure that you're not using 'config -n' 
>> when you generate your compile environment.

>Mike,
>What is the problem caused by using 'config -n'? I use it on every kernel 
>compile. Of course I always use 'make depend all install' when compiling. 
>Just curious.

>Frank

In a nutshell, because the "-D<option>" settings were in the Makefile which
passed them through on the command line, this is not picked up by
"make depend".

For example, if you have a driver that contains:
foo.c:

  ...
  #ifdef SOME_OPTION
    do_something_special();
  #endif
  ...

And you run config with "options SOME_OPTION", it is compiled like this:
cc -c .... -DSOME_OPTION ... foo.c

If you then rerun config -n after having taken out SOME_OPTION,
only the Makefile has changed, and there are no different #include files
for "make depend" to pick up, so the file foo.c is not recompiled when it
most definately should have been.

Also, *never* run "make depend all install"..  Because make starts up and
reads in the Makefile and the .depend.  Then it rebuilds .depend and starts
compiling based on the *in memory* copy of .depend.  It does not load the
new one in.  If you want to do it in a single command line, you need
to do something like this:  "make depend && make all install".  That way,
the "make all" has a complete set of dependencies.

Also, as a BTW, -current is better at this now with the opt_<foo>.h files.

-Peter