[ On Thursday, August 21, 2003 at 08:36:54 (+0100), David Laight wrote: ]
> Subject: Re: build sourcesets problem
>
> > I developed the `sourcesets' option on a system where I have read-only
> > source and separate objdirs, and I don't think there's an easy way to
> > support this option with "in-tree" builds.  So, using objdirs is the
> > recommended approach here.
> > 
> > The difference between -M and -O is as follows:
> > 
> >     -M modp	set MAKEOBJDIRPREFIX to `modp'.
> > 		OBJDIR for /path/to/src/bin/ls becomes
> > 		modp/path/to/src/bin/ls
> > 		(I.e.,  $MAKEOBJDIRPREFIX/`pwd`).
> > 
> >     -O mod	set MAKEOBJDIR to `mod'.
> > 		OBJDIR for /path/to/src/bin/ls becomes
> > 		mod/bin/ls
> > 		(I.e., a "sanitized" path)
> > 
> > -O results in shorter paths under the top of the obj tree, but -M
> > allows for shell tricks like  ls $MAKEOBJDIRPREFIX/$cwd
> > to get to the objdir.  It's all a matter of personal preference.
> 
> With -O you can do other shell tricks like (cd src obj;ls).

Actually you can just about as easily with -M as well, especially given
that any shell supporting that Korn Shell trick has full support for
command aliases too thus making it easy to avoid the extra typing.

For example here's a snippet from my ksh helpers for building netbsd-1-6
on various hosts with target machines being any one of several:

	export HOST_MACHINE=$(uname -m)
	export BUILD_SERVER=proven
	export BUILD_HOME=/$BUILD_SERVER/home/$BUILD_SERVER/$USER

	alias cdalphaobj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-alpha-obj/"
	alias cdi386obj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-i386-obj/"
	alias cdpmaxobj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-pmax-obj/"
	alias cdsparcobj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-sparc-obj/"
	alias cdsun3obj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-sun3-obj/"
	alias cdvaxobj="cd / ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-vax-obj/"

("cd -" of course gets you back to the source directory where you
started from, assuming you've done no intermediate "cd"s)

The "build.sh -M" parameter in this case is of course:

	build.sh -M ${BUILD_HOME}/NetBSD-1.6.x-${HOST_MACHINE}-${TARGET_MACHINE}-obj

Because of symlink and NFS maddness I have to put extra symlinks in
place to make the cd substitution work:

# assume we have a /usr/src-1.6.x symlink pointing to the real CVS
# working directory:
#
#       ln -s ../work/woods/m-NetBSD-1.6 /usr/src-1.6.x
#
# in order to handle going from a $PWD in the /usr/src-1.6.x symlink
# location to the object directory you first need to make sure you
# have any necessary symlinks (for each architecture), such as:
#
#       ln -s work ~/NetBSD-1.6.x-${HOST_MACHINE}-${TARGET}-obj/usr
#       ln -s woods/m-NetBSD-1.6 ~/NetBSD-1.6.x-${HOST_MACHINE}-${TARGET}-obj/usr/src-1.6.x
#
# or, on an NFS client:
#
#       ln -s proven/work ~/NetBSD-1.6.x-${HOST_MACHINE}-${TARGET}-obj/usr
#       ln -s woods/m-NetBSD-1.6 ~/NetBSD-1.6.x-${HOST_MACHINE}-${TARGET}-obj/usr/src
#



> Maybe there should be an option to tell make that there must always
> be an OBJDIR, and that it should never stay in the source directory?

If you want to go that way then maybe X11's "lndir" is better?


> Maybe even be able to make make create the directory on the fly?

That's something I've always wondered about -- avoiding the objdir
creation pass is one step towards avoiding the whole recursive make
inanity!  ;-)


-- 
						Greg A. Woods

+1 416 218-0098                  VE3TCP            RoboHack <woods@robohack.ca>
Planix, Inc. <woods@planix.com>          Secrets of the Weird <woods@weird.com>