-Mrinal Kalakrishnan

Have you ever booted into Windows from Linux just to write a CD because you didn’t know how to do that in Linux? You no longer need to do that. This article will walk you through CD writing under Linux.

If you own a SCSI CD-Writer, you don’t need to recompile the kernel, and you can skip this section. If you have an IDE/ATAPI CD-writer (which is most probable), you’ll have to make it appear like a SCSI device to the CD-writing applications. The Linux kernel has a "SCSI host adapter emulation" module, which does this. But if you don’t want to mess around with kernel configuration, you’re in luck. PC Quest has provided a kernel RPM in this month’s CD, which has the IDE-SCSI module (which is used for SCSI emulation) in it, so all you have to do is install the RPM.

Before you begin, please note that you have to be root before you can perform any of these tasks. It’s still a good idea to work as a user though, and then use the command "su" to become root.

Mount the CD (mount /mnt/cdrom) and then install the RPM with the command:

# rpm -ivh —force /pcq/goodies/kernel/kernel-2.2.14-12-cdwriting.i686.rpm

Now, you have to run LILO to update the boot record. You can do that by typing "lilo –v". Note carefully if there were any errors, then just reboot, and you’ll be running off the new kernel with the IDE-SCSI module. The module is not in memory by default. To load the module, type "modprobe ide-scsi". If you have two CD-ROM drives, the first one will become /dev/scd0, and the second one /dev/scd1. To get back the normal IDE behavior (/dev/hd?), remove the ide-scsi module with the command "rmmod ide-scsi", and load the IDE-CD module with "modprobe ide-cd". By default, if you mount a CD with "mount/mnt/cdrom", it will autoload the IDE-CD module. So, in order to use the SCSI emulation, you’ll have to remove the IDE-CD module first and then load the IDE-SCSI module with "rmmod ide-cd; modprobe ide-scsi".

If you want the normal IDE behavior for your CD-ROM drive and SCSI emulation only for your CD-Writer, then add the following line in /etc/conf.modules:

options ide-cd ignore=hdd

This makes the IDE-CD module ignore your CD-writer (assuming that it is /dev/hdd). Load the IDE-CD module first, followed by the IDE-SCSI module. You can also load the modules at boot time by adding the following two commands in /etc/rc.d/rc.sysinit:

action "Loading ide-cd module" modprobe ide-cd

action "Loading ide-scsi module" modprobe ide-scsi

The program you’ll use to write CDs is called cdrecord, a command-line program. To test if the kernel module is working fine, and if cdrecord can actually find your CD-Writer, type "cdrecord-scanbus". You should get an output that contains the name of your CD-writer, something like this:

Cdrecord release 1.8a29 Copyright (C) 1995-1999 Jörg Schilling

Using libscg version "schily-0.1"

scsibus0:

0,0,0 0) ‘PHILIPS ‘ ‘CDD3610 CD-R/RW ‘ ‘3.01’ Removable CD-ROM

0,1,0 1) *

0,2,0 2) *

0,3,0 3) *

0,4,0 4) *

0,5,0 5) *

0,6,0 6) *

0,7,0 7) *

Make a note of the three numbers next to the name of the CD-Writer (in this case - 0,0,0). These are the SCSI host, id and lun. You have to give these as parameters to cdrecord while writing the CD.