From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 31 Jul 2001 20:37:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 31 Jul 2001 20:37:44 -0400 Received: from prgy-npn1.prodigy.com ([207.115.54.37]:8964 "EHLO deathstar.prodigy.com") by vger.kernel.org with ESMTP id ; Tue, 31 Jul 2001 20:37:38 -0400 Date: Tue, 31 Jul 2001 20:36:14 -0400 Message-Id: <200108010036.f710aEO00457@deathstar.prodigy.com> To: linux-kernel@vger.kernel.org X-Also-Posted-To: comp.os.linux.development.system Subject: Loopback problems in 2.4.x kernels Organization: TMR Associates, Schenectady NY From: davidsen@tmr.com (bill davidsen) Reply-To: davidsen@tmr.com (bill davidsen) X-Newsreader: trn 4.0-test75 (Feb 13, 2001) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing I regularly get CDs written with binary data at the front followed by an iso9660 image. And I have always read then by: mount -o ro,offset=17000 /dev/cdrom /cdrom which works in 2.0 and 2.2 kernels. However, it doesn't work in 2.4.x kernels, at least anything recent enough for me to try, and certainly not in 2.4.[67]. I have already tried: - boot a 2.2 kernel on the same hardware. WORKS - dd the data to a file and offset mount that. WORKS - try both atapi and ide-scsi for device. FAILS - use losetup. FAILS I think the success at mounting the copy of the file shows that the kernels are built correctly, the loop module loads if I build as a module, no errors from the kernel in terms of operation, just an unknown file type. Based on looking at the data, I think the offset is being moved to some multiple of a sector or page size. It's not what I see in the copy on disk in a file. I have been doing this since 2.0.33 and it's been working. I think I remember early 2.4 kernels, or late test releases, working fine, but I don't have a machine to test until the weekend at the earliest. Unless someone has some trick to get by this, consider it a warning and bug report. REPEAT BY: mkisofs -dDRNLJ -o /tmp/small.iso /etc dd if=/dev/random bs=6 count=1 of=/tmp/rxx cat /tmp/rxx /tmp/samll.iso | cdrecord dev=0,0,4 -pad mount -o ro,offset=6 /dev/cdrom /cdrom or whatever is similar on your system. -- bill davidsen CTO, TMR Associates, Inc You have moved your mouse. Before this change can take effect you must reboot your system. Press ENTER now to reboot your system, or any other key to repartition your hard disk and reinstall Windows.