From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261212AbVFPIzK (ORCPT ); Thu, 16 Jun 2005 04:55:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261215AbVFPIzK (ORCPT ); Thu, 16 Jun 2005 04:55:10 -0400 Received: from wproxy.gmail.com ([64.233.184.201]:33868 "EHLO wproxy.gmail.com") by vger.kernel.org with ESMTP id S261212AbVFPIzA convert rfc822-to-8bit (ORCPT ); Thu, 16 Jun 2005 04:55:00 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=tMlXiQZUVPuWPPPS56ectuLJC1zoxdQrt99GzEYx9hvuzuwStO+fu1ItYzez0o6in42oIHhA4HSPnpKS2LYvk0m+qOZIiWEf8QTiL73sg7eKOvRx55PtHLx+BqYm+Y+N/f1zQb1Ryr/DASfA1BR7B+ZMD1HnvJFuyQhr7IGAWsE= Message-ID: Date: Thu, 16 Jun 2005 16:55:00 +0800 From: guorke Reply-To: guorke To: guorke , linux-kernel@vger.kernel.org Subject: Re: mabye simple,but i confused In-Reply-To: <20050616075400.GB57@DervishD> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Content-Disposition: inline References: <20050616075400.GB57@DervishD> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org yes,DervishD.you give me a lot of help! Thanks On 6/16/05, DervishD wrote: > * guorke dixit: > > in understangding the linux kernel, the authors says > > "..Moves itself from address 0x00007c00 to address 0x00090000.." > > > > What i confused is why the Boot Loader do this, i asked google,but > > still no answe. > > who can make me understand it ? > > Well, let's start with the Master Boot Record. In PC's the BIOS > loads the MBR at address 0x7c00, but the MBR is responsible for > loading the OS bootsector, if any. And the bootsectors are written > assuming that they're loaded by a MBR or *by the BIOS itself* so the > address they assume is 0x7c00. But the MBR is already at that > address! What can it do? Well, it moves itself out of the place. > > The problem is that the kernel itself could be loaded directly by > the BIOS (a long time ago, it was possible to boot from a raw floppy > containing an image of the kernel), and the first sector would be > loaded at 0x7c00, so the bootsector, MBR, loader or whatever has to > move out of that address at the very beginning. Why the physical > address 0x00090000 was used? I don't know. Well, it's well at the top > of the 640k base memory and the segment starts with 1001 in binary, > which is a fancy number XDD > > Hope that helps. > > Raúl Núñez de Arenas Coronado > > -- > Linux Registered User 88736 | http://www.dervishd.net > http://www.pleyades.net & http://www.gotesdelluna.net > It's my PC and I'll cry if I want to... >