kernel panic while mounting my cdrom !
 

Hi everybody

I can no more mount my CDRom : each time i try, i get a "kernel panic"
It worked fine until today....and it works fine under windows !

I tried under root also, and it<s the same thing. My DVDRom still works...

What could have happened between yesterday and today ?
Any suggestions ?

What CD is in there? Does this occur with all CDs or just that one?

I tried with a couple of data CD (not Audio).
What disturbs me is that they were correctly seen by window.

Windows is, in general, irrelevant. About all you can say is that 1) the drive is thus not broken, and 2) the CD itself is readable.

Which is useful information, but not overwhelmingly useful, since a kernel panic when mounting a drive is a strange enough occurrence that it implies that the CD drive is not the problem anyway (but instead it's the kernel).

1) What command are you using to mount the drive? Under what circumstances (access via a GUI file manager, trying to open a file on the CD directly with some program, from the command line)?

2) What is the actual output of the kernel panic (why does it say it's panicking)?

3) What kernel is this (uname -r in a terminal)?

1) In command line, i type :
$ cd /mnt
$ mount cdrom1

I don't see any errors from a console in windowmaker, it just jam.

What is in /etc/fstab :

/dev/cdrom /mnt/cdrom iso9660 noauto,owner,user,ro 0 0
/dev/cdrom1 /mnt/cdrom1 iso9660 noauto,owner,user,ro 0 0

2) Here is what could be found in /var/log/messages after i tried to mount:

Jul 28 20:25:10 localhost kernel: Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
Jul 28 20:25:10 localhost kernel: sr0: scsi3-mmc drive: 32x/32x writer cd/rw xa/form2 cdda tray
Jul 28 20:25:45 localhost kernel: scsi : aborting command due to timeout : pid 17, scsi0, channel 0, id 0, lun 0 Read (10) 00 00 00 00 10 00 00 01 00
Jul 28 20:25:45 localhost kernel: hdd: timeout waiting for DMA
Jul 28 20:25:45 localhost kernel: ide_dmaproc: chipset supported ide_dma_timeout func only: 14
Jul 28 20:25:45 localhost kernel: hdd: status timeout: status=0xff { Busy }
Jul 28 20:25:45 localhost kernel: hdd: drive not ready for command

and this is what is said in the boot process :

Jul 28 20:23:56 localhost kernel: scsi0 : SCSI host adapter emulation for IDE ATAPI devices
jui 28 20:23:50 localhost network: Montage de l'interface : succeeded
Jul 28 20:23:56 localhost kernel: Vendor: HP Model: CD-Writer+ 9300 Rev: 1.0c
Jul 28 20:23:56 localhost kernel: Type: CD-ROM ANSI SCSI revision: 02
jui 28 20:23:56 localhost autofs: automount startup succeeded



3) My kernel is : 2.4.18-14


There's 2 words i'm worried about :

1 : SCSI : I don't think i have SCSI devices
2 : DMA (timeout) : The day before it all began, I added memory to my computer (wich seems to work fine).

If you have a CD or DVD drive capable of writing, you don't have SCSI, but you do have scsi emulation. If you do not use this, any CD or DVD drive will be read-only; scsi emulation is what allows you to write to it.

But enabling scsi emulation on writeable removeable drives does often change the device names/locations, as it seems to have done in your case. This line
suggests that your line in /etc/fstab should read something like

/dev/sr0 /mnt/cdrom

since the read-only device formerly at /dev/cdrom has likely been replaced by the read-write device at sr0.

But what's this....?
If you're using automount fs, isn't it possible or even likely that this is the source of the conflict?

If not the CD drives, what, if anything, is automount mounting, and conversely why are you mounting manually when automount is available and running?

You might want to take a look at Autofs Automounter HOWTO, in order to find out how to see what's really going on between the device and this service.

Well, it is solved.

Automount was not involved (I'm not sure of what it does on my system...).
The problem was the DMA configuration of my cdrom. It was set to ultraDMA mode 2, wich is too fast for my hardware. It was probably setup during RedHat install.
To reduce speed I tried :

$ hdparm -d1 -X34 /dev/hdd

as mentionned in http://www.tldp.org/HOWTO/SCSI-2.4-HOWTO/sr.html and the cdrom works now.

I still don't know why my cdrom is called sr0. I guess it's related to the 3 layers of the CDROM subsystem in kernel 2.4. But i didn't found sr0 in my system !

Thank you for all !