2. Setup the Linux-system for writing CD-ROMs

This section applies to the following types of CD-writers: SCSI, IDE/ATAPI and the devices for the parallel port. USB CD-writers are not supported as of May 2000. Non-SCSI writers require compatibility drivers, which make them appear as if they were real SCSI devices. On the one side such a unifying strategy is easy ("everything is SCSI"), because on the application level you can share your knowledge with other users regardless of their kind of CD-writer. On the other side, you have to reconfigure applications like audio CD players or the mount utility to reflect the change of the driver name. For example, if you accessed your ATAPI CD-writer through the device file /dev/hdc before, you will have to access it through /dev/scd0 after activating the SCSI compatibility drivers.

Once you succeed setting up your hardware and the rest of your Linux-system, the command cdrecord -scanbus shows you a list of devices on your SCSI busses. The goal of this section is to guide you in setting up your Linux-system, so that you finally end up seeing something like:

shell> cdrecord -scanbus
Cdrecord release 1.7a1 Copyright (C) 1995-1998 Jörg Schilling
scsibus0:
      0,0,0) 'Quantum ' 'XP34300         ' 'F76D' Disk
      0,1,0) 'SEAGATE ' 'ST11200N        ' '8334' Disk
      0,2,0) *
      0,3,0) 'TOSHIBA ' 'MK537FB/        ' '6258' Disk
      0,4,0) 'WANGTEK ' '5150ES SCSI 36  ' 'ESB6' Removable Tape
      0,5,0) 'EXABYTE ' 'EXB-8500-85QUE  ' '0428' Removable Tape
      0,6,0) 'TOSHIBA ' 'XM-3401TASUNSLCD' '3593' Removable CD-ROM
      0,7,0) *
scsibus1:
      1,0,0) 'Quantum ' 'XP31070W        ' 'L912' Disk
      1,1,0) *
      1,2,0) *
      1,3,0) 'TEAC    ' 'CD-R55S         ' '1.0H' Removable CD-ROM
      1,4,0) 'MATSHITA' 'CD-R   CW-7502  ' '4.02' Removable CD-ROM
      1,5,0) *
      1,6,0) 'YAMAHA  ' 'CDR400t         ' '1.0d' Removable CD-ROM
      1,7,0) *

Listing: Detecting devices on your SCSI bus

The example was provided by Jörg Schilling and shows a total of four CD-writers. Please note that -scanbus also reports other devices, e.g. regular CD-ROMs and hard disk drives. The last column gives the SCSI description of the device, from which you cannot clearly distinguish ordinary CD-ROM drives from those with burning capability. But the product identification (middle column) often has hints about the feature in form of a R, -R or -RW.

2.1 Quickstart

This section is an attempt to provide an fast and easy description of the configuration. Not all possible setups are covered, but please go on and try it out anyways. First of all, check the Linux kernel version printed by the command "uname -r". It should be something like 2.0.X or 2.2.Y, where X is higher than 36 and Y is higher than 11. If you run older versions or the so called development kernels, you are on your own. Installing a new kernel is as much work as fixing an old one, so I have removed all hints you need for buggy kernels.

The listing below shows a set of commands you could start with. The commands create device file entries under /dev unless they already exists.

test `whoami` = 'root' || echo "You must be root to execute the commands."
cd /dev/
umask -S u=rwx,g=rwx,o-rwx
[ -f loop0 ] \
    || ./MAKEDEV loop \
    || for i in 0 1 2 3 4 5 6 7; do mknod loop$i b 7 $i; done
[ -f sg0 -o -f sga ] \
    || ./MAKEDEV sg \
    || for i in 0 1 2 3 4 5 6 7; do mknod sg$i  c 21 $i; done

Listing: creating of devicefiles

Hardware access is usally implemented through device files under Linux. So before any other thing you make sure those files do exists in the directory /dev. Still nobody could give me a compelling reason why this has not been automated through techniques like the device filesystem (devfs). The devfs is available for years know, brings a safer (!) and a far clearer naming of devices and makes the device entries appear automatically under /dev. Some prominent people argue devfs is not the perfect solution, but they do not come up with anything better, not even something comparable and last but least nothing available and tested now. Lets start to use devfs, so I can remove the above commands from this document. ( http://www.atnf.CSIRO.AU/~rgooch/linux/kernel-patches.html)

Next thing to ensure is, that the Linux kernel is equiped with the necessary drivers. The following commands check various files for the presence of drivers in the running Linux kernel. Usally the command "cdrecord -scanbus" should trigger an automatic loading of all drivers. In case a driver is not present in the kernel afterwards, it is reported and the modularized driver (module) is manually loaded through insmod.

test `whoami` = 'root' || echo "You must be root to execute the commands."
cdrecord -scanbus > /dev/null
if ! (pidof kerneld || test -f "/proc/sys/kernel/modprobe"); then
    echo "Neither kerneld nor kmod are running to automatically load modules".
fi
report_no_autoload() {
    echo "Ensure the module $1 is loaded automatically next time."
}
if test ! -f "/proc/scsi/scsi"; then
    report_no_autoload scsi_mod  &&  insmod scsi_mod
fi
if ! grep "^........ sg_" /proc/ksyms > /dev/null; then
    report_no_autoload sg  &&  insmod sg
fi
if ! grep "^........ sr_" /proc/ksyms > /dev/null; then
    report_no_autoload sr_mod  &&  insmod sr_mod
fi
if ! grep "^........ loop_" /proc/ksyms > /dev/null; then
    report_no_autoload loop  &&  insmod loop
fi
if ! grep iso9660 /proc/filesystems > /dev/null; then
    report_no_autoload iso9660  &&  insmod iso9660
fi
echo "The following is only needed for IDE/ATAPI CD-writers."
if ! grep ide-scsi /proc/ide/drivers > /dev/null; then
    report_no_autoload ide-scsi  &&  insmod ide-scsi
fi
cdrecord -scanbus

Listing: Testing for drivers

Please read the next chapter if insmod complains about missing module files. If you are in text mode (console), the loading of modules may cause some messages to be printed on your screen. If you are in graphics mode (X11, KDE, Gnome), you can recall these messages with the command dmesg.

There are several ways to load the modules next time you start up your Linux system:

(1) Put the relevant insmod command into the startup sequence
    (a shell script named rc.local or equivalent).
(2a) Run kerneld or kmod and
(2b) configure them in /etc/modules.conf (to be more precise,
     you configure the utility modprobe, which is called by the daemons)

People with a SCSI-writer can skip the rest of this section, because cdrecord will most likely already detect their hardware. If not, then please send me an email with some information about your setup, so I can improve the section about SCSI-writers.

Now to the people with CD-writers for IDE/ATAPI. As written in the previous chapter, you have to load the compatibility driver ide-scsi. But this driver can only access your CD-Writer if no other driver has already done so. In other words, you have to tell the regular IDE driver to leave your CD-writer unrecognized, so the ide-scsi driver can grab it.

hda = IDE bus/connector 0 master device
hdb = IDE bus/connector 0 slave  device
hdc = IDE bus/connector 1 master device
hdd = IDE bus/connector 1 slave  device

Table: device file names of IDE/ATAPI devices

The table above shows the relation of device file names and the placing of devices on the IDE busses. The device file name representing your CD-Writer has to be passed to the driver in the Linux kernel. Example: hdb=ide-scsi. Such a setting should be added to lilo.conf or chos.conf if the driver is statically compiled into your kernel, which seems to be the most common setup. If you need to pass more than one parameter to the kernel, then seperate them with spaces (like shown in the chos example). The next two listings show example configurations containing more lines than just the relevant append-line. Please note the append- and cmdline-entries are image-specific (ie. don't add them immediatly at the top).

image=/boot/zImage-2.2.14
  label=Linux
  read-only
  append="hdb=ide-scsi"

Listing: Example configuration for lilo (/etc/lilo.conf)

linux "Linux 2.1.14" {
        image=/boot/zImage-2.0.37
        cmdline= root=/dev/hda5 readonly hdb=ide-scsi
}

Listing: Example configuration for chos (/etc/chos.conf)

If the driver for IDE/ATAPI CD-ROMs is loaded as a module, then the above won't make any difference to you, but make sure you include the options-line from the next listing. The last three lines of that listing are generally suggested to further automate the loading of the required modules.

options ide-cd ignore=hdb            # tell the ide-cd module to ignore hdb
alias scd0 sr_mod                    # load sr_mod upon access of scd0
#pre-install ide-scsi modprobe imm    # uncomment for some ZIP drives only
pre-install sg     modprobe ide-scsi # load ide-scsi before sg
pre-install sr_mod modprobe ide-scsi # load ide-scsi before sr_mod
pre-install ide-scsi modprobe ide-cd # load ide-cd   before ide-scsi

Listing: Example configuration for /etc/modules.conf

If your CD-writer is the only CD-ROM attached to your machine, then remember you have to access the CD-ROM in the writer through the device file /dev/scd× where ×=0,..,8. You may want to change the symbolic name cdrom to point to the new device file name. The listing below shows the command to achieve this with the example scd0.

cd /dev && rm cdrom && ln -s scd0 cdrom

Listing: Making cdrom a symbolic name for scd0

If your CD-writer and CD-ROM-drive are two different devices, then don't change the cdrom symlink.

Special notes about SCSI CD-writers

Please make sure that your writer is recognized by the BIOS of your SCSI hostadaptor card. Every SCSI hostadaptor scans the SCSI bus after power on and reports all devices found connected to the bus. The report includes the SCSI ID of the devices and their product label. It makes no sense to proceed unless your CD writer is listed in that report.

If you plan to connect your SCSI device through the parallel port (not to confuse with the IDE drives for the parallel port), you need a special active cable and a special kernel driver. Read http://www.torque.net/parport/parscsi.html to learn more about this option.

Special notes about CD-writers for the parallel port

I have no clue about this, sorry. Please read http://www.torque.net/parport/paride.html or your local file /usr/src/linux/Documentation/paride.txt.

Compiling missing kernel modules (optional)

You don't need to read this section if you hardware is already sucessfully recognized and configured by the previously described configuration steps.

The Linux kernel can be equipped with drivers for various features. You can compile the drivers into the kernel image statically or you can compile them as a module for on-demand loading. The last method is preferred for drivers not essential for bringing your Linux-system into life, because your kernel will be smaller and faster then. However, some drivers are essential for the system to come up and you shouldn't compile them as a module. Example: if your system lives on an IDE hard disk, you must have the driver for IDE hard disks in the kernel -- not as a module.

There are three different types of CD-writers: SCSI, IDE/ATAPI and external writers that work through the parallel port. The table shows how to configure the Linux kernel for those hardware types. The first column of the table is the section of the kernel configuration menu, where you can find the setting. The second column is the description of the feature (taken from the kernel configuration menu, too). The third column gives the name of the resulting module. The columns named SCSI, IDE and PP contain the necessary options for the associated hardware (PP = parallel port).

Sect.  Description                 Module   SCSI  IDE   PP
------------------------------------------------------------
BLOCK  Enhanced IDE/MFM/RLL...                     Y      
BLOCK  IDE/ATAPI CDROM             ide-cd          M     
BLOCK  SCSI emulation support      ide-scsi        M      
BLOCK  Loopback device             loop       M    M     M

PARIDE Parallel port IDE device    paride               Y/M
PARIDE Parallel port ATAPI CD-ROMs                       M
PARIDE Parallel port generic ATAPI                       M
PARIDE (select a low-level driver)                       Y

SCSI   SCSI support                scsi_mod  Y/M  Y/M    
SCSI   SCSI CD-ROM support         sr_mod    Y/M  Y/M     
SCSI     Enable vendor-specific               Y    Y      
SCSI   SCSI generic support        sg        Y/M  Y/M     
SCSI   (select a low-level driver)            Y

FS     ISO 9660 CDROM filesystem   iso9660   Y/M  Y/M   Y/M
FS     Microsoft Joliet cdrom...   joliet     Y    Y     Y

Table: driver selection for different writer types

Y stands for yes and means you should put the beast into the kernel. M stands for module and means you should or must compile this feature as a module. Y/M gives you the option to decide between either (order indicates choices with less potential problems). Empty settings don't need to be modified and not changing them increases the chance that the resulting kernel will work for you (if it did before...). Especially in environments where SCSI and ATAPI devices are mixed, you better build most things as modules.

Compiling loopback device is optional. It allows you to test the image before writing it to the media. If you want to be able to read CD-ROMs, you need support for the ISO 9660 filesystem. This driver automatically includes RockRidge Extensions. The Microsoft Joliet CD-ROM extensions have to be explicitly added to the ISO 9660 filesystem. In any case, you need a low-level driver for your hardware. Low-level refers to the driver, which interacts directly with the hardware. For SCSI and the parallel port, there are a lot of low-level drivers available.

Installing the resulting Linux-kernel is beyond the scope of this HOWTO. Please consult the documentation of your Linux-distribution.

Users of RedHat Linux be aware that you have to compile in the features "Ramdisk support" and "Initial ramdisk". Furthermore, you have to generate a new ramdisk with the new modules by issuing a command like "mkintrd --preload ide-cd initrd-2.2.14.img 2.2.14".

2.2 Get the user software for burning CD-Rs

A more detailed survey of tools related to produce CD-ROMs is available from http://www.fokus.gmd.de/research/cc/glone/employees/joerg.schilling/private/cdb.html.

Command line utilities

One of the following packages are required to generate images of CD-Rs (only required for data CD-ROMs):

ftp://tsx-11.mit.edu/pub/linux/packages/mkisofs/ (mkisofs)

ftp://ftp.ge.ucl.ac.uk/pub/mkhfs (mkhybrid)

To write images to the CD-R, you need one of the following software packages:

ftp://ftp.fokus.gmd.de/pub/unix/cdrecord/ (cdrecord)

http://www.ping.de/sites/daneb/cdrdao.html (cdrdao)

http://www.munich-vision.de/vcd/ (mkvcdfs)

Don't trust the man page of old versions of mkisofs which state you need version 1.5 of cdwrite. Just use cdrecord and you are fine. Please note that newer versions of cdrecord ship with an enhanced version of mkisofs and some extra tools in the subdirectory misc/ (readcd, isosize) not found elsewhere.

Graphical user interfaces (optional)

Front-ends are really front-ends under Linux. That means, you still have to install the command-line utilities, but you access them in a better looking manner.

X-CD-Roast is a program package dedicated to easy CD creation under Linux. It combines command line tools like cdrecord and mkisofs into a nice graphical user interface.

http://www.fh-muenchen.de/home/ze/rz/services/projects/xcdroast/e_overview.html

BurnIT is a JAVA front-end to cdrecord, mkisofs and cdda2wav-0.95 making it a complete package for burning CDs on the Unix platform. It is available from

http://sunsite.auc.dk/BurnIT/

CD-Tux is a character based frontend for the programs mkisofs and cdrecord. "It creates an easy to use enviroment for doing almost anything to a CD in full color through the use of the (in)famous NCURSES Library. And it does all this whith an executable of under 75K."

http://www.datadictator.co.za/cdtux/