linux-kernel - Re: [tip:x86/urgent] x86: Add back _end symbol that is missing from Symbol.map

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Message-ID: <20091108124232.GA4205@elte.hu>
Date:	Sun, 8 Nov 2009 13:42:32 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	hare@...e.de, akpm@...ux-foundation.org, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86: Add back _end symbol that is missing from
 Symbol.map


* Sam Ravnborg <sam@...nborg.org> wrote:

> On Sun, Nov 08, 2009 at 12:48:29PM +0100, Ingo Molnar wrote:
> > 
> > * Sam Ravnborg <sam@...nborg.org> wrote:
> > 
> > > On Sun, Nov 08, 2009 at 11:07:12AM +0000, tip-bot for Hannes Reinecke wrote:
> > > > Commit-ID:  d1e4d37b79e944f6351ae38eb1ca7c9f7b506e76
> > > > Gitweb:     http://git.kernel.org/tip/d1e4d37b79e944f6351ae38eb1ca7c9f7b506e76
> > > > Author:     Hannes Reinecke <hare@...e.de>
> > > > AuthorDate: Wed, 4 Nov 2009 07:19:32 -0800
> > > > Committer:  Ingo Molnar <mingo@...e.hu>
> > > > CommitDate: Sun, 8 Nov 2009 12:05:03 +0100
> > > > 
> > > > x86: Add back _end symbol that is missing from Symbol.map
> > > > 
> > > > With 2.6.31 'crash' on x86_64 falls flat on its face as the
> > > > '_end' symbol is missing from the System.map file.
> > > > 
> > > > The culprit is commit 091e52c3551d3031343df24b573b770b4c6c72b6,
> > > > which moved the '_end' symbol into it's own section.  Apparently
> > > > this causes kallsyms to not reference it properly.
> > > > 
> > > > So do not include _end in it's own section.
> > > > 
> > > > Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> > > > Cc: Sam Ravnborg <sam@...nborg.org>
> > > > Cc: <stable@...nel.org> # .31.x
> > > > LKML-Reference: <200911041519.nA4FJWEW030164@...p1.linux-foundation.org>
> > > > Signed-off-by: Ingo Molnar <mingo@...e.hu>
> > > 
> > > I'm afraid this will break a RELOCTABLE i386 kernel.
> > > 
> > > We fixed this up some time ago where we had to
> > > move the symbol definition inside a section
> > > to prevent the symbol being absolute.
> > 
> > ah, indeed. So ... the question is then, why did _end disappear from 
> > System.map?
>
> I think ld discards zero size sections. No need to keep them around if 
> they are empty.
> 
> Following patch should fix it up in a better way.

thanks Sam, that was fast!

> I reused most of Hannes changelog.

Hannes, if it works for you then please resend the patch with your 
signoff so we can send it upstream-wards.

Thanks,

	Ingo
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