linux-kernel - Re: Patch "i386: Relocatable kernel support" causes instant reboot

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Message-Id: <1166723157.29546.281560884@webmail.messagingengine.com>
Date:	Thu, 21 Dec 2006 18:45:57 +0100
From:	"Alexander van Heukelum" <heukelum@...tmail.fm>
To:	"Jean Delvare" <khali@...ux-fr.org>,
	"Vivek Goyal" <vgoyal@...ibm.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Andi Kleen" <ak@...e.de>, "LKML" <linux-kernel@...r.kernel.org>
Subject: Re: Patch "i386: Relocatable kernel support" causes instant reboot

On Thu, 21 Dec 2006 14:59:22 +0100, "Jean Delvare" <khali@...ux-fr.org>
said:
> Hi Vivek,
> 
> On Thu, 21 Dec 2006 08:43:26 +0530, Vivek Goyal wrote:
> > On Thu, Dec 21, 2006 at 02:13:54PM +0100, Jean Delvare wrote:
> > > On Thu, 21 Dec 2006 06:38:14 +0530, Vivek Goyal wrote:
> > > > Looks like it might be a tool chain issue. I took Jean's config file and
> > > > built my own kernel and I am able to boot the kernel. But I can't boot
> > > > his bzImage. I observed the same behaviour as jean is experiencing. It jumps
> > > > back to BIOS.
> > > 
> > > I can only confirm that. I installed a more recent system on the same
> > > hardware, rebuilt a kernel from the same config file, and now it boots
> > > OK. So it's not related to the hardware. It has to be a compilation-time
> > > issue.
> > 
> > Looks like you have already trashed your setup. If not, is it possible to
> 
> No, of course I didn't. I installed the new system on a different hard
> disk drive.
> 
> > upload the output of "objdump -D arch/i386/boot/setup.o"? This will give
> > some info regarding what assembler is doing.
> 
> Here you go:
> http://jdelvare.pck.nerim.net/linux/relocatable-bug/setup.asm

Hi,

Hmm. taking a peek at the bzImage there...

00001d80  41 00 56 45 53 41 00 56  69 64 65 6f 20 61 64 61 
|A.VESA.Video ada|
00001d90  70 74 65 72 3a 20 00 00  00 b8 00 00 55 aa 5a 5a  |pter:
......U.ZZ|
00001da0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00 
|................|
*
00001e00  4e 35 13 00 1f 8b 08 00  23 a4 89 45 02 03 b4 fd 
|N5......#..E....|
          -- -- -- -- ^^ ^^ ^^

This is the end of the realmode kernel, and it should be followed by the
32-bit code that is to be executed at (normally) 0x100000, right? This
is however not the case here. Where did arch/i386/boot/compressed/head.S
go then? What is the significance of this value 0x0013354e? It is in
fact
exactly the size of the compressed kernel image.

I have no idea what went wrong, but it went wrong in the build process
of the bzImage.

Hope this helps,
    Alexander

> -- 
> Jean Delvare
> -
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-- 
  Alexander van Heukelum
  heukelum@...tmail.fm

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