From: lsanfil@marvell•com (sanfilippo)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH 0/1] Wrong structure alignment due to compiler attribute "section"
Date: Wed, 4 Mar 2015 12:40:34 +0100 [thread overview]
Message-ID: <54F6EF32.7080306@marvell.com> (raw)
In-Reply-To: <20150303144130.GB5177@e103592.cambridge.arm.com>
On 03.03.2015 15:41, Dave Martin wrote:
Dave,
thanks for your response.
> For the element _size_ issue, I'm confused. On 32-bit, that
> structure is clearly 196 bytes in size, with the alignment requirement
> of void * (4 bytes)... so there's no clear reason why the linker
> shouldn't be inserting extra padding.
>
> I can't reproduce this with my current tools (upstream binutils-2.24,
> gcc-4.9.2).
>
>
> Can you try to track down where this discrepancy is coming from?
>
> i.e.,
>
> * If you're juggling with multiple kernel trees, make sure there
> are not differences between them that could be causing this, such
> as changes to linker scripts or header files that are involved
> in building these arrays.
I can reproduce this with a vanilla kernel (3.19) from kernel.org. What
I do is:
- configure the kernel with mvebu_v5_defconfig
- compile it
However this issue occurs (so far) only with this special toolchain:
http://www.plugcomputer.org/405/us/gplugd/tool-chain/arm-marvell-linux-gnueabi.tar.bz2
If you like you can try this yourself. I am sure that you will get the
same results.
I tried the same with three other toolchains but with those the problem
did not occur. I also tried other kernel configurations with that
"problematic" toolchain, but also the problem did not occur any more.
So I think its either a bug in that compiler/linker or the current
solution in vmlinux.lds.h does not work correct under some special
circumstances.
>
> * See what the input to the assembler looks like, with regard to
> .align directives.
>
> * See what the alignment of the affected sections is in each individual
> .o file.
Not sure what exactly I should check here. Could you be a bit more precise?
> * See what __alignof__(struct of_device_id) evaluates to.
It evaluates to "4" even for the bad case.
Regards,
Lino
next prev parent reply other threads:[~2015-03-04 11:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-02 10:01 [RFC PATCH 0/1] Wrong structure alignment due to compiler attribute "section" Lino Sanfilippo
2015-03-02 10:01 ` [RFC PATCH 1/1] ARM: Ensure correct structure alignment when using " Lino Sanfilippo
2015-03-03 14:41 ` [RFC PATCH 0/1] Wrong structure alignment due to " Dave Martin
2015-03-04 11:40 ` sanfilippo [this message]
2015-03-04 14:35 ` Dave Martin
2015-03-04 16:29 ` Lino Sanfilippo
2015-03-05 12:26 ` Dave Martin
2015-03-05 13:20 ` Lino Sanfilippo
2015-03-05 13:47 ` Dave Martin
2015-03-05 15:32 ` Lino Sanfilippo
2015-03-05 17:33 ` Dave Martin
2015-03-06 14:02 ` Lino Sanfilippo
2015-03-06 18:20 ` Lino Sanfilippo
2015-03-22 0:56 ` Lino Sanfilippo
2015-03-24 12:07 ` Dave Martin
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