linux-kernel - Re: [Q] x86

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Message-ID: <20080223090739.GB6747@cvg>
Date:	Sat, 23 Feb 2008 12:07:39 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Yinghai Lu <yhlu.kernel@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>, Sam Ravnborg <sam@...nborg.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Q] x86 - boot/header.S

[Yinghai Lu - Sat, Feb 23, 2008 at 12:44:49AM -0800]
| On Sat, Feb 23, 2008 at 12:20 AM, Cyrill Gorcunov <gorcunov@...il.com> wrote:
| > Hi Peter, Sam,
| >
| >  could you take a look on x86/boot/header.S:280 please?
| >
| >  # Zero the bss
| >         movw    $__bss_start, %di
| >         movw    $_end+3, %cx
| >         xorl    %eax, %eax
| >         subw    %di, %cx
| >         shrw    $2, %cx
| >         rep; stosl
| >
| >  I wonder why is $_end there instead of $__bss_stop?
| >  Well, accroding to vmlinux_32.lsd both _end and __bss_stop
| >  are the same BUT __bss_stop is more convenient methink.
| >  Would it be usefull to change?
| 
| we should have head32.c like head64.c
| and x86_32_start_kernel.
| 
| Eric's patch long time ago...
| 
| YH
| 

Hi Yinghai,

thanks for reply BUT that is not the point (or maybe I miss something).

Look, we only have head64.c - there is no head32.c at all. Both
vmlinux_32/64.lds defines _end exactly the same as __bss_stop. So in
code which DO fillup bss section with zeros the prefered name is
__bss_stop. The only thing I'm trying to say that it would be clean
naming scheme and I think it would help for further review - instead
of searching all over x86 files to find _end definition __bss_stop
tell us WHAT we are zeroing from the code.

		- Cyrill -
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