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Date: Thu, 2 Aug 2007 07:13:23 +0200
From: Borislav Petkov <bbpetkov@yahoo.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Xudong Guan <xudong.guan@gmail.com>, linux-kernel@vger.kernel.org,
       Chuck Ebbert <cebbert@redhat.com>, michal.k.k.piotrowski@gmail.com
Subject: Re: 2.6.23-rc1: no setup signature found... SOLVED!
Message-ID: <20070802051323.GA4152@gollum.tnic>
Reply-To: bbpetkov@yahoo.de
References: <20070729085059.GA10758@gollum.tnic> <20070729092402.GA2272@xguan-laptop> <20070729103706.GA16780@gollum.tnic> <46AC9B28.6060906@zytor.com> <20070729191528.GA5166@gollum.tnic> <46ADF02F.7010800@zytor.com> <20070730185359.GA4290@gollum.tnic> <46AE4E29.7060402@zytor.com> <20070801043835.GA4676@gollum.tnic> <46B09A57.8000403@zytor.com>
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On Wed, Aug 01, 2007 at 10:36:07AM -0400, H. Peter Anvin wrote:
> Borislav Petkov wrote:
>> 	Breakpoint 4, 0x00040200 in ?? ()
>> 	1: x/i ($cs << 4) + $eip  0x40300:      lea    (%si),%dx
>> 	(gdb) c
>> 	Continuing.
>> if i do delete here, it loads the second stage of grub and continues to 
>> load the
>> kernel. Is there another way to land at the jmp instruction instead of 
>> poking
>> blindly, maybe disassemble something parts of the initial code. \me 
>> reading
>> grub-docs...
>
> If you do "delete" without a breakpoint number, you're deleting all 
> breakpoints.  I just experimented with grub, and it looks like it should 
> break at 0x90200, so just set that breakpoint and none of the others.
>
> 	-hpa

Hi,

now this is one of those cases where one tries to shoot a small fly with a
nuclear missile. The first assumption that something was wrong with the kernel
setup code was wrong and here's how i know:

The problem with my version of grub not hitting the breakpoint 0x90200 made me
think that something might be messed up in the grub part of the boot sequence.
Thus, i did the qemu simulation again and noticed on the initial boot screen of
grub it saying "Grub version 0.91." However, you remember from a different post
that the version of grub i have is the latest to be found in debian unstable,
0.97-29, so i thought that something has to be wrong with it and especially with all
those grub stages binaries, in my case in /boot/grub, which grub-install setups.
Checking their timestamps revealed that the files are from 2004 so i thought,
well, these are OLD! :) After refreshing the grub installation and replacing
the stages-binaries with the fresh ones, the kernel booted just fine :), here:

[boris@gollum:07:02:07:~:9994)->  uname -a
Linux gollum 2.6.22-4fd06960f120e02e9abc802a09f9511c400042a5-12 #12 PREEMPT Thu Jul 26 18:08:34 CEST 2007 i686 GNU/Linux

so i guess the problem was with the ancient parts of a grub installation i had
lying around which weren't replaced by the apt-get update process and somehow
messed up newer grub versions. Anyway, in the end one still learns a lot while at it.

Thanks for your help.

-- 
Regards/Gru?,
    Boris.
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