linux-kernel - Re: Build failure in -next due to 'kbuild: allow archs to select link dead code/data elimination'

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Message-ID: <20160913120014.1036bf91@roar.ozlabs.ibm.com>
Date:   Tue, 13 Sep 2016 12:00:14 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Michal Marek <mmarek@...e.com>, Chen Liqin <liqin.linux@...il.com>,
        Lennox Wu <lennox.wu@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: Build failure in -next due to 'kbuild: allow archs to select
 link dead code/data elimination'

On Mon, 12 Sep 2016 15:24:43 -0700
Guenter Roeck <linux@...ck-us.net> wrote:

> Hi,
> 
> your commit 'kbuild: allow archs to select link dead code/data elimination'
> is causing the following build failure in -next when building score:defconfig.
> 
> arch/score/kernel/built-in.o: In function `work_resched':
> arch/score/kernel/entry.o:(.text+0xe84):
> 	relocation truncated to fit: R_SCORE_PC19 against `schedule'
> 
> Reverting the commit fixes the problem.
> 
> Please let me know if I can help tracking down the problem.
> In case you need a score toochain, you can find the one I use at
> http://server.roeck-us.net/toolchains/score.tgz.
> 
> Thanks,
> Guenter

It's not supposed to have any real effect unless the
option is selected, but there are a few changes to linker
script which must be causing it.

There are two changes to vmlinux.lds.h. One is to KEEP a
few input sections, that *should* be kept anyway. The other
is to bring in additional sections into their correct output
section.

Could you try reverting those lines of vmlinux.lds.h that
change the latter, i.e.:

-		*(.text.hot .text .text.fixup .text.unlikely)		\
+		*(.text.hot .text .text.fixup .text.unlikely .text.*)	\


-		*(.bss)							\
+		*(.bss .bss.[0-9a-zA-Z_]*)				\

etc?

Thanks,
Nick