> Date: Sun, 17 Dec 1995 12:32:57 -0500
> From: Greg Hudson <ghudson@mit.edu>
> Sender: owner-current-users@netbsd.org
> Precedence: list
> X-Loop: current-users@NetBSD.ORG
> 
> Comments?  Do people like this?  Do people go "ewww?"  Can people
> think of simpler ideas?  The lack of a good system for doing NetBSD
> builds out of a read-only source tree has caused some problems here.

Cleaning up the obj part of the build process might be a good idea.

If you are looking for a quick solution, though, maybe you should use
a union mount.  I've been using union mounts to build NetBSD for
several months, and it seems to work pretty well.  The only problem
has been the use of the /dev/vnd* in making boot floppies (/dev/vnd
does not work on union mounts, but you can fix this with symbolic
links).

Here's what I did:

I added UNION to my kernel config file and built a new kernel (doing a
make clean first, which was unfortunately necessary).  My source is
under /u/sup/src, and I wanted to build under ~/obj.  As myself (not
as root), I ran "mount -t union -o -b /u/sup/src ~/obj".

This situation is more-or-less ideal, because I can edit files on the
union mount and new copies will appear in my home directory.  Files I
don't touch will continue to track the latest version.  The only
strange thing is that if you delete files on a union mount, shadow
objects will be created to hide the underlying versions.  To view the
shadow objects use "ls -W", and to remove them use "rm -W".

David