linux-kernel - Re: Urgent: x86-32 and GNU ld 2.22.52.0.1

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Date:	Fri, 18 May 2012 12:55:51 -0400
From:	Josh Boyer <jwboyer@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"H.J. Lu" <hjl.tools@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg KH <gregkh@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@...el.com>
Subject: Re: Urgent: x86-32 and GNU ld 2.22.52.0.1

On Fri, May 18, 2012 at 12:20 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 05/18/2012 09:14 AM, H.J. Lu wrote:
>> On Fri, May 18, 2012 at 8:56 AM, H. Peter Anvin <hpa@...or.com> wrote:
>>> I need an urgent opinion.  It seems we have an epic mess on our hands.
>>>
>>> GNU ld 2.22.52.0.1 silently changed the semantics of section-relative
>>> symbols that are part of otherwise empty sections, and silently changes
>>> them to absolute.  We rely on section-relative symbols staying
>>> section-relative, and actually have several sections in the linker
>>> script solely for this purpose.
>>
>> That is I talked to you a couple days ago:
>>
>> http://sourceware.org/bugzilla/show_bug.cgi?id=14052
>>
>
> I know, which was a very good thing... otherwise we'd probably not have
> tracked this down anywhere near as quickly.  Thank you.
>
> The problem is that this version of binutils made it into Fedora 17, and
> so we now have a large number of users with a known bad binutils in the
> field...

We've not seen many kernel bugs that would seem to be blamed on this as
of yet.  It does seem like a problem waiting to hit us once F17 goes GA
though.  My limited 32-bit F17 machine collection definitely shows the
__init_{begin,end} symbols being absolute, but they boot fine.  Likely
because the kernel isn't relocated on them.

For what it's worth, I've filed a bug against Fedora binutils here:
https://bugzilla.redhat.com/show_bug.cgi?id=822981

josh
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