From: Al Viro <viro@ZenIV.linux.org.uk>
To: Ramkumar Ramachandra <artagnon@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Richard Weinberger <richard@nod.at>,
Jeff Dike <jdike@addtoit.com>
Subject: Re: [PATCH 1/3] arch/um/Makefile: remove dead code
Date: Fri, 5 Jul 2013 13:23:52 +0100 [thread overview]
Message-ID: <20130705122352.GR4165@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CALkWK0mcK13RiVjNCrgwEaaL3nBZ1W0R5+cHAhbqiOmRE4UjAg@mail.gmail.com>
On Fri, Jul 05, 2013 at 04:12:30PM +0530, Ramkumar Ramachandra wrote:
> Al Viro wrote:
> > [...]
> > IOW, any make variable (== macro in POSIX quote above) can be explicitly
> > set in make(1) command line in form name=value and in that case nothing in
> > makefile(s) can change its value. It's true for GNU make, it's true for
> > BSD make and it's been true for historical Unix make since its introduction
> > in v7.
>
> Thanks Al, the education is much appreciated. I always thought =
> would override it, and ?= was for default value.
?= is a different story - it refuses to override _any_ earlier declarations,
including ones in makefile itself. GNU make has added it fairly late, BTW -
in 3.77 (1998); BSD make has grown it at some point during the rewrite
Adam de Boor had been doing in late 80s. NFI whether he'd invented it or
picked it elsewhere - there had been a lot of cross-pollination between the
variants of make(1) all along...
next prev parent reply other threads:[~2013-07-05 12:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-04 21:03 [PATCH 0/3] Get defconfig to work with ARCH=um Ramkumar Ramachandra
2013-07-04 21:03 ` [PATCH 1/3] arch/um/Makefile: remove dead code Ramkumar Ramachandra
2013-07-04 21:14 ` Richard Weinberger
2013-07-04 23:53 ` Al Viro
2013-07-05 10:42 ` Ramkumar Ramachandra
2013-07-05 12:23 ` Al Viro [this message]
2013-07-04 21:03 ` [PATCH 2/3] arch/um/configs: add defconfig for i386, x86_64 Ramkumar Ramachandra
2013-07-04 21:03 ` [PATCH 3/3] arch/um: migrate to using defconfig in configs/ Ramkumar Ramachandra
2013-07-04 21:27 ` [PATCH 0/3] Get defconfig to work with ARCH=um richard -rw- weinberger
2013-07-04 22:21 ` Ramkumar Ramachandra
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