From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753251AbYLWXeZ (ORCPT ); Tue, 23 Dec 2008 18:34:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751267AbYLWXeQ (ORCPT ); Tue, 23 Dec 2008 18:34:16 -0500 Received: from 1wt.eu ([62.212.114.60]:1246 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751244AbYLWXeQ (ORCPT ); Tue, 23 Dec 2008 18:34:16 -0500 Date: Wed, 24 Dec 2008 00:34:10 +0100 From: Willy Tarreau To: Martin Schlemmer Cc: linux-kernel@vger.kernel.org Subject: Re: Initramfs from existing vmlinuz Message-ID: <20081223233410.GC6800@1wt.eu> References: <49518245.3D93.006F.0@nwu.ac.za> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49518245.3D93.006F.0@nwu.ac.za> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 24, 2008 at 12:28:53AM +0200, Martin Schlemmer wrote: > Hi > > I had a bit of an accident, and wondered if somebody already had to try to extract the initramfs image from an existing vmlinuz? > > I did try google, but either my search terms was not right, or nobody really touched on the subject before, because all the results mostly dealt with an external image. > > Any advice will be appreciated. yes, it happens to me from time to time. You first have to extract and uncompress the ELF image from vmlinuz. For this, look for the gzip signature 1F 8B 08 in your vmlinuz, and feed all data starting from this point to zcat. Either you do the same on the resulting file -and you may find several compressed images- or you simply pass it through "objdump -h". It will show you a .init.ramfs section. Use the fourth field as the file offset, and dump from that position. You'll find your initramfs, likely starting with 1F 8B 08 since it's supposed to be compressed with gzip. You need an hex editor, dd, zcat and objdump for this. It's not much complicated once you have the tools, but it might require a few attempts before finding the right image (I tend to find config.gz before initramfs). Regards, Willy