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Date: Thu, 23 Nov 2000 11:32:48 +0100
From: Vojtech Pavlik <vojtech@suse.cz>
To: Rogier Wolff <R.E.Wolff@bitwizard.nl>
Cc: Peter Samuelson <peter@cadcamlab.org>,
        Patrick van de Lageweg <patrick@bitwizard.nl>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rogier Wolff <wolff@bitwizard.nl>
Subject: Re: [NEW DRIVER] firestream
Message-ID: <20001123113248.A2897@suse.cz>
In-Reply-To: <20001122234047.N2918@wire.cadcamlab.org> <200011230822.JAA05965@cave.bitwizard.nl>
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In-Reply-To: <200011230822.JAA05965@cave.bitwizard.nl>; from R.E.Wolff@bitwizard.nl on Thu, Nov 23, 2000 at 09:22:09AM +0100
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On Thu, Nov 23, 2000 at 09:22:09AM +0100, Rogier Wolff wrote:
> Peter Samuelson wrote:
> 
> > > +int loopback = 0;
> > > +int fs_debug = 0;
> > > +struct fs_dev *fs_boards = NULL;
>  
> > Aside from the 'static' issue already mentioned, these should be left
> > uninitialized.  ('gcc -fassume-bss-zero' would be nice, but then again
> > in userspace it rarely matters.)
> 
> Hi Peter, thanks for the feedback. 
> 
> Actually, I have an opinion on this matter: If the initialization
> value doesn't really matter that much, I like leave out the
> initialization, as you suggest.
> 
> However, if my code assumes that the compiler needs to initialize the
> variable one way or another, I want to put in the initialization, even
> if that means an "= 0;" which is already the default.
> 
> This is a form of documentation.

If it didn't matter in the object code, it would be just documentation.
But uninitialized variables are put into the .bss segment, which is not
included in the object (and is assumed to be zero on start), while
initialized ones (even to zero) are put into the .data segment, which
*is* in the object file.

Thus a difference of 12 bytes code size in your case (on a 32 bit system).

-- 
Vojtech Pavlik
SuSE Labs
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