From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754518Ab3KGXvK (ORCPT <rfc822;w@1wt.eu>);
	Thu, 7 Nov 2013 18:51:10 -0500
Received: from ozlabs.org ([203.10.76.45]:35846 "EHLO ozlabs.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751010Ab3KGXvD (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 7 Nov 2013 18:51:03 -0500
From: Rusty Russell <rusty@rustcorp.com.au>
To: Axel Lin <axel.lin@ingics.com>, Ming Lei <tom.leiming@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>, Michal Marek <mmarek@suse.cz>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: kernel BUG at kernel/kallsyms.c:222!
In-Reply-To: <CAFRkauDe7V3N0AbfvE_=GEXHZ_Fw62VsA8p50wSUYE1-TRqMfw@mail.gmail.com>
References: <1383789208.5970.1.camel@phoenix> <CACVXFVMn6RSXchQ8u47F35_J+YSnp1bwF1tr-8uCEYwvFsOfgQ@mail.gmail.com> <CAFRkauAEt-YhBt11opj_GVCLrxGsTSd2LowWGmukTSmGuJkd3A@mail.gmail.com> <CACVXFVO=QA-R1+twCL9fc_3vASg6Ap-3ezi=tU1MV1pdPYrfWw@mail.gmail.com> <CAFRkauAdR3=ByE0_B3OsqOBjmbz2a02EXb+6g-vn=1TJ7AZc8Q@mail.gmail.com> <CACVXFVMaLOfDvzdn_1NryQY59cgtLdMMqHL-_ZAa95MPz4p56Q@mail.gmail.com> <CAFRkauDe7V3N0AbfvE_=GEXHZ_Fw62VsA8p50wSUYE1-TRqMfw@mail.gmail.com>
User-Agent: Notmuch/0.15.2 (http://notmuchmail.org) Emacs/23.4.1 (i686-pc-linux-gnu)
Date: Fri, 08 Nov 2013 10:14:44 +1030
Message-ID: <87zjpf4w0j.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Axel Lin <axel.lin@ingics.com> writes:
> 2013/11/7 Ming Lei <tom.leiming@gmail.com>:
>> Hi,
>>
>> On Thu, Nov 7, 2013 at 10:47 AM, Axel Lin <axel.lin@ingics.com> wrote:
>>>
>>> hi Ming,
>>> Seems CONFIG_PAGE_OFFSET is not configurabe in "make menuconfig".
>>> And I found CONFIG_PAGE_OFFSET=0xC0000000 for all below configs...
>>> $ make at91_dt_defconfig; grep  CONFIG_PAGE_OFFSET .config
>>> $ make ep93xx_defconfig; grep  CONFIG_PAGE_OFFSET .config
>>> $ make imx_v4_v5_defconfig; grep CONFIG_PAGE_OFFSET .config
>>> $ make mxs_defconfig; grep CONFIG_PAGE_OFFSET .config
>>> $ make omap2plus_defconfig; grep CONFIG_PAGE_OFFSET .config
>>> $ make s3c6400_defconfig; grep CONFIG_PAGE_OFFSET .config
>>> $ make at91x40_defconfig; grep CONFIG_PAGE_OFFSET .config
>>> ( at91x40_defconfig is also arm7tdmi )
>>
>> Firstly it can be configured via VMSPLIT_3GVMSPLIT_2G/VMSPLIT_1G.
>>
>> Secondly, configurable or not isn't the point, and maybe some uclinux
>> platforms do not use CONFIG_PAGE_OFFSET at all, but they should
>> set it as a reasonable value or at least be below than the start link
>> address of vmlinux.
>
> Hi Ming,
>
> I found in arch/arm/include/asm/memory.h:
> CONFIG_PAGE_OFFSET is not used if !CONFIG_MMU.
> So looks like setting CONFIG_PAGE_OFFSET to other value still won't work.

This seems like the simplest solution, but it may mean you still have
crap in /proc/kallsyms.

Does it work for you?

Thanks,
Rusty.


diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 32b10f53d0b4..c3bd3efec4cc 100644
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -82,7 +82,9 @@ kallsyms()
 		kallsymopt="${kallsymopt} --all-symbols"
 	fi
 
-	kallsymopt="${kallsymopt} --page-offset=$CONFIG_PAGE_OFFSET"
+	if [ -n "${CONFIG_MMU}" ]; then
+		kallsymopt="${kallsymopt} --page-offset=$CONFIG_PAGE_OFFSET"
+	fi
 
 	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"