Message-ID: <4104961b0901222237h7fac5b1vf1b3b7f9d06d550c@mail.gmail.com>
Date:	Fri, 23 Jan 2009 14:37:12 +0800
From:	jidong xiao <jidong.xiao@...il.com>
To:	Cliff Wickman <cpw@....com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: How to generate a Kerntypes file?

On Thu, Jan 22, 2009 at 9:31 PM, Cliff Wickman <cpw@....com> wrote:
> Hi Jason,
>
> On Thu, Jan 22, 2009 at 06:59:34PM +0800, jidong xiao wrote:
>> Hi,All,
>>
>> Sometimes when I install a kernel I saw there is a Kerntypes file
>> installed under /boot directory, but sometimes no, I remember when I
>> install a sles9 kernel, there must be a Kerntypes file installed, but
>> most of other kernels doesn't include such a Kerntypes file. This file
>> is very useful for me to do some analysis, so I hope I can generate it
>> every time I build a kernel. Do I need a patch for this or there are
>> already some patches I can take use of?Thanks.
>
> You had a init/kerntypes.c in sles9 and sles10. It included a lot
> of basic kernel types.  It was compiled with -g to make the kerntypes.
> I presume that you used the LKCD project's lcrash with the kerntypes.
>
Hi, Cliff,

Thanks for your guides.

Well yes I am intending to use lcrash to load the kernel debug information.

I noticed that recently kdb is going to be able to print out kernel
structures, and now I want to test that feature, I started my
experiments by reading the instructions inside
kdb/modules/kdbm_debugtypes.c which is saying:

 * Usage:
 *  in order for the insmod kdbm_debugtypes.ko to succeed in loading types
 *  you must first use  lcrash -t kerntypes.xxxx -o debug_info
 *  and echo debug_info > /proc/kdb/debug_info_name

so I have to generate kerntypes file. I looked into init/kerntypes.c,
it seems there is nothing but just includes some header files, like
below:

     16 #include <linux/compile.h>
     17 #include <linux/module.h>
     18 #include <linux/mm.h>
     19 #include <linux/vmalloc.h>
     20 #include <linux/config.h>
     21 #include <linux/utsname.h>
     22 #include <linux/kernel_stat.h>
     23 #include <linux/dump.h>
     24
     25 #include <asm/kerntypes.h>

We can see here are 9 files are included, does this mean the resulted
Kerntypes file only provides kernel structures that are defined within
these 9 files? If I want to print out more kernel structures I need to
change this file so as to include more header files?

In addition, if I want to generate Kerntypes file via building a
mainline kernel(rather than SLES kernel), the only thing I need to do
is:
1. add this init/kerntypes.c and include/asm/kerntypes.h into kernel
source code.
2. change the Makefile accordingly.

After that I just compile the kernel as usual and I should be able to
get the Kerntypes file(which is actually nothing but just
init/kerntypes.o), right?

Regards
Jason

> If you download lkcd (lkcd.svn.sourceforge.net) you also build a
> tool called dwarfextract.  It is able to pull all the structure
> definitions out of a -g (CONFIG_DEBUG_INFO) kernel and any selected
> modules.  That is useful with the lcrash command.
>
> If you want to analyze your live system or a dump with the crash command
> (people.redhat.com/~anderson/) you don't need the kerntypes, as you use
> the -g kernel itself.  Although you may make kerntypes with dwarfextract
> and use them with crash also.
>
> -Cliff
>
>> Regards
>> Jason
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>
> --
> Cliff Wickman
> Silicon Graphics, Inc.
> cpw@....com
> (651) 683-3824
>
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