Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 16 Aug 2002 05:48:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 16 Aug 2002 05:48:39 -0400 Received: from willy.net1.nerim.net ([62.212.114.60]:31498 "EHLO www.home.local") by vger.kernel.org with ESMTP id ; Fri, 16 Aug 2002 05:48:38 -0400 Date: Fri, 16 Aug 2002 11:52:30 +0200 From: Willy Tarreau To: Misha Alex Cc: linux-kernel@vger.kernel.org Subject: Re: your mail Message-ID: <20020816095230.GA14227@alpha.home.local> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1864 Lines: 39 Hello ! On Fri, Aug 16, 2002 at 07:51:37AM +0000, Misha Alex wrote: > Also i tried the linear addressing linear = c*H*S + h*S +s -1 .But > linear or linear*512 never gave me the exact byte offset to seek. > > I am working in linux and using a hexeditor to seek .How many exact bytes > should i seek to find out the extended partition.I read the MBR and found > the exteneded partiton. > 00 01 01 00 02 fe 3f 01 3f 00 00 00 43 7d 00 00 > 80 00 01 02 0b fe bf 7e 82 7d 00 00 3d 26 9c 00 > 00 00 81 7f 0f fe ff ff bf a3 9c 00 f1 49 c3 01 > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 I haven't played with this for a long time, but I still have some memory about this. First, when an offset is higher than 8GB, there's no way to code it with the bios' CHS scheme as you find it in the partition table. I see that you know how to decode this, so set all the CHS bits to ones and look at the offset. For this reason, we often use only the size to locate these partitions. If I recall correctly, the last 4 bytes of your parts are the sizes in sectors. For example, hda2 is 9c263d sectors long, which equals 5.2 GB. You'll notice that bytes 8 to 11 of each partitions are nearly equivalent to the size of the previous part. They should be the start offset in sectors. So in this case, hda3 begins at 9ca3bf (byte 5255953920), and is 1c349f1 sectors long (15.1 GB). I think that 'fe ff ff' after the partition type indicates that only the linear mode should be used, but I'm not sure about this nor I do I have any proof. You should read the partition code to get more clues, IMHO. Hoping this helps, Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/