Date: Wed, 16 Aug 2006 17:03:14 +0200
From: Andi Kleen <ak@muc.de>
To: vgoyal@in.ibm.com
Cc: linux kernel mailing list <linux-kernel@vger.kernel.org>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       Fastboot mailing list <fastboot@lists.osdl.org>,
       Don Zickus <dzickus@redhat.com>
Subject: Re: [PATCH] x86_64: Re-positioning the bss segment
Message-Id: <20060816170314.f16f8afa.ak@muc.de>
In-Reply-To: <20060815214952.GB11719@in.ibm.com>
References: <20060815214952.GB11719@in.ibm.com>
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On Tue, 15 Aug 2006 17:49:52 -0400
Vivek Goyal <vgoyal@in.ibm.com> wrote:

> 
> o Currently bss segment is being placed somewhere in the middle (after .data)
>   section and after bss lots of init section and data sections are coming.
>   Is it intentional?

Not that I know of.

> 
> o One side affect of placing bss in the middle is that objcopy keeps the
>   bss in raw binary image (vmlinux.bin) hence unnecessarily increasing
>   the size of raw binary image. (In my case ~600K). It also increases
>   the size of generated bzImage, though the increase is very small
>   (896 bytes), probably a very high compression ratio for stream
>   of zeros.
> 
> o This patch moves the bss at the end hence reducing the size of
>   bzImage by 896 bytes and size of vmlinux.bin by 600K.
> 
> o This change benefits in the context of relocatable kernel patches. If
>   kernel bss is not part of compressed data (vmlinux.bin) then it does
>   not have to be decompressed and this area can be used by the decompressor
>   for its execution hence keeping the memory requirements bounded and 
>   decompressor code does not stomp over any other data loaded beyond
>   kernel image (As might be the case with bootloaders like kexec).

Merged thanks. 

Does i386 need a similar change?

-Andi

 
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