Messages in this thread | | | Date | Fri, 04 Jul 1997 14:46:33 -0400 | From | Jonathan Freeson <> | Subject | Re: Linux ISO9660 File System |
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Eric Youngdale wrote:
> On Sun, 29 Jun 1997, Jonathan F. Freeson wrote: > > > Hello: > > > > I noticed that with some of the later 2.1.x kernels, I have been > unable to > > read some of my older "Shareware" CD-ROMs that I was able to read > with > > 2.0.30. With 2.1, I frequently got the kernel message: > > What are the kernel messages you get when you mount this disc? > > What type of cdrom drive are you using?
I get the exact same results with both of my CDRORM drives, one being a SCSI, NEC Multipspin 3Xp, and the other being an IDE, CyberDrive 16x.
Below is a small excerpt of what messages I get. The exact same thing happens when I use /dev/hdc instead of /dev/scd0. Am I doing anything wrong?
[root@jonspc /mnt]# mount /dev/scd0 cdrom2 mount: block device /dev/scd0 is write-protected, mounting read-only [root@jonspc /mnt]# cd cdrom2 [root@jonspc cdrom2]# ls bwcc.dll* gif/ gocd.exe* readme.txt* viewers/ catalog.dir* gif2bmp.exe* gocdwin.exe* unzip.exe* vocwav/ eurodem/ gif2bmp.pif* mkgrp.exe* unzip.pif* fli/ gocd.doc* mods/ utils/ [root@jonspc cdrom2]# cd mods [root@jonspc mods]# ls z* (<---- I don't think you want to see 100+ error messages) Directory entry extends past end of iso9660 block ls: zine_sfx.zip: No such file or directory Directory entry extends past end of iso9660 block ls: zoltan.zip: No such file or directory [root@jonspc mods]# mount /dev/hda6 on / type ext2 (rw) /dev/hda1 on /dosc type vfat (rw) none on /proc type proc (rw) /dev/scd0 on /mnt/cdrom2 type iso9660 (ro) [root@jonspc mods]#
(Kernel Messages in /var/log/messages using Redhat 4.2) Jul 4 14:07:34 jonspc kernel: Directory entry extends past end of iso9660 block Jul 4 14:07:34 jonspc kernel: Directory entry extends past end of iso9660 block
> > > The theory behind the change is that cdrom discs have a fixed > sector size - normally 2048 bytes, but 512 byte sector discs do come > up > from time to time. Directories themselves contain a series of > directory > entries, and the idea is that a single directory entry should never > span > a sector boundary. > > The fact that you are getting this message either indicates > defective premastering of the disc itself, or it indicates that the > driver > for the cdrom drive you are using is somehow broken. >
Based on your comments, I would think that the premastering process is defective, since I am using two different drives on different interface types. However, I had a chance to try this on another machine since I don't have access to another Linux box. In DOS, I don't recall having any problems on any other machine (I know this doesn't mean much).
> The main motivation for making the change now was that their > is > a lot of ugly overhead in piecing together two adjacent extents to > form > the directory entry that lies on a sector boundary. (This was > originally > added because the original cdrom drivers always gave back 1K sectors) > > Hope this explains things a bit. > > -Eric
I see. As a verification then, with my kudge of a patch as I understand it, this extra overhead only occurs when I encounter one of these defective disks. Otherwise, if I were to leave this "fix" in my kernel, the only performance hit I would take with non-defective disks would be the slightly larger code, and the execution of two additional IF statements (if I recall the patch correctly). Otherwise, my system should be stable (with regard to the isofs driver).
Just for reference, I have multiple CDROMs that produce this problem (I estimate around 10). I purchased all of them from the same company. I don't recall the exact name of the company, but here are the example titles and other info that may be useful:
1. Mega Windows #3 --- (C) 1994 MEGA-ROM INC. (C) 1994 Profit Press (First (C) is on the CDROM case, the other on the actual CD) Best of Shareware, Sights & Sounds -- (C) 1994 Best of Productions (Part of a 6 disc set)
The above error output was with the "Sights & Sounds" disk, there are about 100 files in this directory that cause this problem.
Thanks.
---Jonathan Freeson jfreeson@sun.science.wayne.edu
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