linux-kernel - Re: .version keeps being updated

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Date:	Thu, 11 Jan 2007 13:05:25 +0000
From:	Andy Whitcroft <apw@...dowen.org>
To:	Roman Zippel <zippel@...ux-m68k.org>
CC:	Linus Torvalds <torvalds@...l.org>,
	Jean Delvare <khali@...ux-fr.org>,
	Andrey Borzenkov <arvidjaar@...l.ru>,
	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
	Herbert Poetzl <herbert@...hfloor.at>,
	Olaf Hering <olaf@...fle.de>
Subject: Re: .version keeps being updated

Roman Zippel wrote:
> Hi,
> 
> On Wed, 10 Jan 2007, Linus Torvalds wrote:
> 
>> This part:
>>
>> 	const char __init linux_banner[] =
>>
>> CANNOT work, because the stupid SuSE tool that look into the kernel binary 
>> searches for "Linux version " as the thing, and as such the "linux_banner" 
>> has to be the _first_ thing to trigger it for it to work.
> 
> Unless the SuSE tool is completely stupid, it should actually work:
> 
> $ strings vmlinux | grep "Linux version"
> Linux version 2.6.20-rc3-git7 (roman@...id) (gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)) #7 SMP Wed Jan 10 14:20:10 CET 2007
> $

Try compiling a kernel with CIFS enabled and you will find the output
somewhat different.  And herein lies the rub, if the proc string is
__initdata then it falls to the bottom, and the tool takes the first
entry starting from 'Linux version ', which matches these incorrect
lines and the tool fails.

> 
>> Which is why "__init" is wrong. It causes the linker to either put it at 
>> the end of the thing (which would break the SuSE tool). Alternatively it 
>> causes section mismatch problems ("init" and "const" don't work that well 
>> together), in which case it might work, but only due to toolchain bugs.
> 
> The const could be dropped, but it shouldn't hurt much either...

Longer term I do wonder if the linker section idea mooted elsewhere in
this thread would fly.

-apw
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