linux-kernel - Re: [PATCH] Make bootsector stub 16-bit-only (i386)

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Message-Id: <20070508032817.e4734798.akpm@linux-foundation.org>
Date:	Tue, 8 May 2007 03:28:17 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Alexander van Heukelum <heukelum@...lshack.com>
Cc:	Andi Kleen <ak@...e.de>, "H. Peter Anvin" <hpa@...or.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Make bootsector stub 16-bit-only (i386)

On Sat, 5 May 2007 12:44:52 +0200 Alexander van Heukelum <heukelum@...lshack.com> wrote:

> The x86 bzImage contains a stub to inform people that it is not possible
> any more to run a Linux kernel by catting it to a floppy and then
> booting from it. This was meant to be all 16-bit code. The first
> instruction, however, ended up as being coded as a 16:32-bit far jump. I
> assume the intention was a 16:16-bit far jump.
> 
> This patch changes only i386.
> 
> Greetings,
> 	Alexander
> 
> Signed-off-by: Alexander van Heukelum <heukelum@...lshack.com>
> 
> ---
> 
> diff --git a/arch/i386/boot/bootsect.S b/arch/i386/boot/bootsect.S
> index 011b7a4..ae9df0d 100644
> --- a/arch/i386/boot/bootsect.S
> +++ b/arch/i386/boot/bootsect.S
> @@ -44,7 +44,7 @@ #endif
>  _start:
>  
>  	# Normalize the start address
> -	jmpl	$BOOTSEG, $start2
> +	jmpw	$BOOTSEG, $start2

Sigh, another blow struck in the ongoing struggle between my Vaio and the
rest of the world.

Stone-cold black-screen lockup immediately upon boot.

Stock FC5 install, config at
http://userweb.kernel.org/~akpm/config-sony.txt
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