linux-kernel - Re: "." in vmlinux.lds.S

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Date:	Fri, 6 Jun 2014 12:08:31 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Hán Shěn (沈涵) <shenhan@...gle.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	X86 ML <x86@...nel.org>
Subject: Re: "." in vmlinux.lds.S

On Fri, Jun 6, 2014 at 11:53 AM, Hán Shěn (沈涵) <shenhan@...gle.com> wrote:
> Yeah, the symbol "__end_rodata_hpage_align" is defined as absolute in
> older binutils, the newer binutils making it relative seems
> meaningless in this context.

What I mean is: what actually changes in the linker output when the
symbol is relative?

--Andy

>
> On Fri, Jun 6, 2014 at 11:40 AM, Andy Lutomirski <luto@...capital.net> wrote:
>> On 06/06/2014 10:08 AM, Hán Shěn (沈涵) wrote:
>>> A gentle ping?
>>>
>>> On Tue, Jun 3, 2014 at 2:46 PM, Hán Shěn (沈涵) <shenhan@...gle.com> wrote:
>>>> Hi we are trying to boot up a x86_64 chrome book using binutils 2.24 and
>>>> kernel 3.8, but failed.
>>>>
>>>> After some triage work, we found that a 2-year-old binutil CL changed the
>>>> interpretation of "." in linker script （short story: absolute -> relative,
>>>> long story: https://sourceware.org/ml/binutils/2012-06/msg00155.html).
>>>>
>>>> After some further work, we are able to boot the kernel with a kernel patch
>>>> pasted at EOM. I am curious, why the upstream kernel is never hit by this
>>>> behavior? We enabled "CONFIG_DEBUG_RODATA", so we were hit, is this some
>>>> macro not usually turned on?
>>
>> What does a section-relative symbol do?
>>
>> --Andy
>
>
>
> --
> Han Shen |  Software Engineer |  shenhan@...gle.com |  +1-650-440-3330



-- 
Andy Lutomirski
AMA Capital Management, LLC
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