linux-kernel - Re: [PATCH 0/4] elf core: Write section header table first

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Message-Id: <20110104100253.42560a2d.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 4 Jan 2011 10:02:53 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	HATAYAMA Daisuke <d.hatayama@...il.com>
Cc:	linux-kernel@...r.kernel.org, tony.luck@...el.com,
	jdike@...toit.com, dhowells@...hat.com, gerg@...pgear.com,
	roland@...hat.com, oleg@...hat.com, mingo@...e.hu,
	viro@...iv.linux.org.uk, andi@...stfloor.org,
	alan@...rguk.ukuu.org.uk, akpm@...ux-foundation.org,
	kosaki.motohiro@...fujitsu.com, suzuki@...ibm.com,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH 0/4] elf core: Write section header table first

On Thu, 30 Dec 2010 06:16:17 +0900
HATAYAMA Daisuke <d.hatayama@...il.com> wrote:

> This patchset changes a position of section header table, if exists,
> from the last to the next to ELF header. According to ELF
> specification, the order of ELF component layout is not specified
> except for ELF header. See:
> 
>   http://www.sco.com/developers/gabi/latest/ch4.intro.html#file_format
> 
> The merits are:
>  - reducing tracing memory maps from 3 times to 2 times.
>  - simple offset handling that makes the code easier to read.
> 

Hmm ? What was problem ? And new layout can be handled by usual tools ?
As gdb, readelf, objdump...etc.


>  arch/ia64/kernel/elfcore.c |   16 -----
>  arch/um/sys-i386/elfcore.c |   16 -----
>  fs/binfmt_elf.c            |  136 +++++++++++++++++-------------------------
>  fs/binfmt_elf_fdpic.c      |  141 ++++++++++++++++++--------------------------
>  include/linux/elfcore.h    |    1 -
>  kernel/elfcore.c           |    5 --
>  6 files changed, 111 insertions(+), 204 deletions(-)
> 
> I built and tested this patchset on x86_64. I also built it on ia64,
> um-i386 and frv using cross compilers to cover the range.
> 
> Here's a program useful to generate ELF core with many program header
> entries, and three steps to produce such ELF core:
> 
>  $ sysctl vm.max_map_count=70000
>  $ ulimit -c unlimted
>  $ mkmmap 65535
> 

What difference will be seen between before/after your patch ?
coredump will be quicker ?

Thanks,
-Kame

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