Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754813AbbKYEdq (ORCPT <rfc822;w@1wt.eu>);
	Tue, 24 Nov 2015 23:33:46 -0500
Received: from mga11.intel.com ([192.55.52.93]:63716 "EHLO mga11.intel.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754299AbbKYEdp (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 24 Nov 2015 23:33:45 -0500
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.20,341,1444719600"; 
   d="scan'208";a="846571316"
Date: Tue, 24 Nov 2015 20:33:44 -0800
From: Andi Kleen <ak@linux.intel.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: Michal Marek <mmarek@suse.cz>, Stephen Rothwell <sfr@canb.auug.org.au>,
        linux-next@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: LTO build errors (Re: linux-next: clean up the kbuild tree?)
Message-ID: <20151125043344.GG8438@tassilo.jf.intel.com>
References: <20151115112705.0bf4f0ed@canb.auug.org.au>
 <20151115175848.GD10150@tassilo.jf.intel.com>
 <5649D3B9.7020701@suse.cz>
 <20151121010033.GB8438@tassilo.jf.intel.com>
 <s5h4mgfzkno.wl-tiwai@suse.de>
 <20151124021231.GE8438@tassilo.jf.intel.com>
 <s5hy4dnicgv.wl-tiwai@suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <s5hy4dnicgv.wl-tiwai@suse.de>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2548
Lines: 54


Hi Takashi,

On Tue, Nov 24, 2015 at 05:33:36PM +0100, Takashi Iwai wrote:
>   LD      vmlinux
> arch/x86/kernel/cpu/perf_event_intel_rapl.c:66:20: error: rapl_domain_names causes a section type conflict with __setup_str_set_reset_devices
>  static const char *rapl_domain_names[NR_RAPL_DOMAINS] __initconst = {
>                     ^
> init/main.c:159:19: note: ‘__setup_str_set_reset_devices’ was declared here
>  __setup("reset_devices", set_reset_devices);
> 
> Hmm...  I see no direct relation, but OK, let's try to get rid of
> __initconst.  Now it hits lots of other errors like:

I hit the same issue, will send a patch. The other symbol is typically some
random correct symbol because gcc detects the conflict on a pair of symbols.

The problem is that placing const correctly is too difficult, the correct line
would be 

static const char *const rapl_domain_names[NR_RAPL_DOMAINS] __initconst = {

> 
> `__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
> `__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
> `__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)
> `__sw_hweight32' referenced in section `.text' of /tmp/ccUCMU7n.ltrans13.ltrans.o: defined in discarded section `.text' of lib/built-in.o (symbol from plugin)

This needs

https://git.kernel.org/cgit/linux/kernel/git/ak/linux-misc.git/commit/?h=lto-4.0&id=d826425f7a9d935d521989bd0a871b76fb4c59e2


> /tmp/ccUCMU7n.ltrans21.ltrans.o: In function `do_exit':
> <artificial>:(.text+0xfc0): undefined reference to `sys_futex'
> /tmp/ccUCMU7n.ltrans22.ltrans.o: In function `_do_fork':
> <artificial>:(.text+0x39f7): undefined reference to `ret_from_fork'
> <artificial>:(.text+0x4428): undefined reference to `ret_from_kernel_thread'


That's new, but can be fixed by adding __visible or asmlinkage to these symbols
I guess it's from the recent entry* restructuring.

I'll do an updated tree later.

Everything that's called from assembler in C needs to be marked like this. It's
fairly mechanic.

-andi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/