linux-kernel - Re: [Ocfs2-devel] [PATCH 1/1] OCFS2: Remove NULL assignments on static

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Date:	Wed, 9 Apr 2014 13:44:48 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Wengang <wen.gang.wang@...cle.com>
Cc:	Fabian Frederick <fabf@...net.be>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	ocfs2-devel@....oracle.com
Subject: Re: [Ocfs2-devel] [PATCH 1/1] OCFS2: Remove NULL assignments on
 static

On Wed, 09 Apr 2014 08:53:14 +0800 Wengang <wen.gang.wang@...cle.com> wrote:

> ___ 2014___04___09___ 04:13, Fabian Frederick ______:
> > static values are automatically initialized to NULL.
> >
>
> What's the badness if we do the assignments?

(top-posting repaired...)

Back in the olden days,

	static int x = 0;

would consume space in the .data segment and

	static int x;

would consume space in the .bss segment.


The .data segment is a part of vmlinux (because it contains non-zero
data) whereas .bss does not occupy space in vmlinux because .bss is
all-zero and can be built at runtime

So the effect of this patch would be to reduce the size of the kernel
image.  Less disk space, less ROM space, etc.


I think more recent gcc's and linkers got smarter about that and move
initialized-to-zero .data into .bss anyway.

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