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IDE-CD driver documentation

19 May 1996

scott snyder  

1. Introduction

---------------

The ide-cd driver should work with all ATAPI 1.2 compliant cdrom

drives which attach to an IDE interface.  Note that some cdrom vendors

(including Mitsumi, Sony, Creative, Aztech, and Goldstar) have made

both ATAPI-compliant drives and drives which use a proprietary

interface.  If your drive uses one of those proprietary interfaces,

this driver will not work with it (but one of the other cdrom drivers

probably will).  This driver will not work with `ATAPI' drives which

attach to the parallel port.  In addition, there is at least one drive

(CyCDROM CR520ie) which attaches to the IDE port but is not ATAPI;

this driver will not work with drives like that either (but see the

aztcd driver).

This driver provides the following features:

 - Reading from data tracks, and mounting iso9660 filesystems.

 - Playing audio tracks.  Most of the cdrom player programs floating

   around should work; i usually use Workman.

 - Multisession support.

 - On drives which support it, reading digital audio data directly

   from audio tracks.  The program cdda2wav can be used for this.

   Note, however, that only a few drives actually support this

   function; the only ones which i've heard of successes with are Sony

   and Toshiba drives.

 - There is now rudimentary support for cdrom changers which comply

   with the ATAPI 2.6 draft standard (such as the NEC CDR-251).  This

   merely adds a function to switch between the slots of the changer

   under control of an external program.  A sample such program is

   appended to the end of this file.  The Sanyo 3-disc changer

   (which does not conform to the standard) is also now supported.

   Please note the driver refers to the first CD as slot # 0.

2. Installation

---------------

0. The ide-cd relies on the ide disk driver.  See

   Documentation/ide.txt for up-to-date information on the ide

   driver.

1. Make sure that the ide and ide-cd drivers are compiled into the

   kernel you're using.  When configuring the kernel, say `yes' to the

   options

      Enhanced IDE/MFM/RLL disk/cdrom/tape support

      Include IDE/ATAPI CDROM support

   and `no' to

      Use old disk-only driver on primary interface

   Depending on what type of IDE interface you have, you may need to

   specify additional configuration options.  See

   Documentation/ide.txt.

2. You should also ensure that the iso9660 filesystem is either

   compiled into the kernel or available as a loadable module.  You

   can see if a filesystem is known to the kernel by cat'ing the file

   /proc/filesystems.

3. The cdrom drive should be connected to the host on an IDE

   interface.  Each interface on a system is defined by an I/O port

   address and an IRQ number, the standard assignments being

   0x170 and 14 for the primary interface and 0x1f0 and 15 for the

   secondary interface.  Each interface can control up to two devices,

   where each device can be either a hard drive, a cdrom drive, or a

   tape drive.  The two devices on an interface are called `master'

   and `slave'; this is usually selectable via a jumper on the drive.

   Linux names these devices as follows.  The master and slave devices

   on the primary IDE interface are called `hda' and `hdb',

   respectively.  The drives on the secondary interface are called

   `hdc' and `hdd'.  (Interfaces at other locations get other letters

   in the third position; see Documentation/ide.txt.)

   If you want your cdrom drive to be found automatically by the

   driver, you should make sure your IDE interface uses either the

   primary or secondary addresses mentioned above.  In addition, if

   the cdrom drive is the only device on the IDE interface, it should

   be jumpered as `master'.  (If for some reason you cannot configure

   your system in this manner, you can probably still use the driver.

   You may have to pass extra configuration information to the kernel

   when you boot, however.  See Documentation/ide.txt for more

   information.)

4. Boot the system.  If the drive is recognized, you should see a

   message which looks like

     hdb: NEC CD-ROM DRIVE:260, ATAPI CDROM drive

   If you do not see this, see section 5 below.

5. You may want to create a symbolic link /dev/cdrom pointing to the

   actual device.  You can do this with the command

     ln -s  /dev/hdX  /dev/cdrom

   where X should be replaced by the letter indicating where your

   drive is installed.

6. You should be able to see any error messages from the driver with

   the `dmesg' command.

3. Basic usage

--------------

An iso9660 format cdrom can be mounted by putting the disc in the

drive and typing (as root)

  mount -t iso9660 /dev/cdrom /mnt/cdrom

where it is assumed that /dev/cdrom is a link pointing to the actual

device (as described in step 5 of the last section) and /mnt/cdrom is

an empty directory.  You should now be able to see the contents of the

cdrom under the /mnt/cdrom directory.  If you want to eject the cdrom,

you must first dismount it with a command like

  umount /mnt/cdrom

Note that audio cds cannot be mounted.

Some distributions set up /etc/fstab to always try to mount a cdrom

filesystem on bootup.  It is not required to mount the cdrom in this

manner, though, and it may be a nuisance if you change cdroms often.

You should feel free to remove the cdrom line from /etc/fstab and

mount cdroms manually if that suits you better.

Multisession and photocd discs should work with no special handling.

The hpcdtoppm package (ftp.gwdg.de:/pub/linux/hpcdtoppm/) may be

useful for reading photocds.

To play an audio cd, you should first unmount and remove any data

cdrom.  Any of the cdrom player programs should then work (workman,

workbone, cdplayer, etc.).  Lacking anything else, you could use the

cdtester program in Documentation/cdrom/sbpcd.

On a few drives, you can read digital audio directly using a program

such as cdda2wav.  The only types of drive which i've heard support

this are Sony and Toshiba drives.  You will get errors if you try to

use this function on a drive which does not support it.

For supported changers, you can use the `cdload' program (appended to

the end of this file) to switch between changer slots.  Note that the

drive should be unmounted before attempting this.  The program takes

two arguments: the cdrom device, and the slot number to which to change.

If the slot number is -1, the drive is unloaded.

4. Compilation options

----------------------

There are a few additional options which can be set when compiling the

driver.  Most people should not need to mess with any of these; they

are listed here simply for completeness.  A compilation option can be

enabled by adding a line of the form `#define  1' to the top

of ide-cd.c.  All these options are disabled by default.

VERBOSE_IDE_CD_ERRORS

  If this is set, ATAPI error codes will be translated into textual

  descriptions.  In addition, a dump is made of the command which

  provoked the error.  This is off by default to save the memory used

  by the (somewhat long) table of error descriptions.

STANDARD_ATAPI

  If this is set, the code needed to deal with certain drives which do

  not properly implement the ATAPI spec will be disabled.  If you know

  your drive implements ATAPI properly, you can turn this on to get a

  slightly smaller kernel.

NO_DOOR_LOCKING

  If this is set, the driver will never attempt to lock the door of

  the drive.

CDROM_NBLOCKS_BUFFER

  This sets the size of the buffer to be used for a CDROMREADAUDIO

  ioctl.  The default is 8.

TEST

  This presently enables an additional ioctl which enables a user-mode

  program to execute an arbitrary packet command.  See the source for

  details.  This should be left off unless you know what you're doing.

5. Common problems

------------------

This section discusses some common problems encountered when trying to

use the driver, and some possible solutions.  Note that if you are

experiencing problems, you should probably also review

Documentation/ide.txt for current information about the underlying

IDE support code.  Some of these items apply only to earlier versions

of the driver, but are mentioned here for completeness.

In most cases, you should probably check with `dmesg' for any errors

from the driver.

a. Drive is not detected during booting.

   - Review the configuration instructions above and in

     Documentation/ide.txt, and check how your hardware is

     configured.

   - If your drive is the only device on an IDE interface, it should

     be jumpered as master, if at all possible.

   - If your IDE interface is not at the standard addresses of 0x170

     or 0x1f0, you'll need to explicitly inform the driver using a

     lilo option.  See Documentation/ide.txt.  (This feature was

     added around kernel version 1.3.30.)

   - If the autoprobing is not finding your drive, you can tell the

     driver to assume that one exists by using a lilo option of the

     form `hdX=cdrom', where X is the drive letter corresponding to

     where your drive is installed (see section 2).  Note that if you

     do this and you see a boot message like

       hdX: ATAPI cdrom (?)

     this does _not_ mean that the driver has successfully detected

     the drive; rather, it means that the driver has not detected a

     drive, but is assuming there's one there anyway because you told

     it so.  If you actually try to do I/O to a drive defined at a

     nonexistent or nonresponding I/O address, you'll probably get

     errors with a status value of 0xff.

   - Some IDE adapters require a nonstandard initialization sequence

     before they'll function properly.  (If this is the case, there

     will often be a separate MS-DOS driver just for the controller.)

     IDE interfaces on sound cards often fall into this category.

     Support for some interfaces needing extra initialization is

     provided in later 1.3.x kernels.  You may need to turn on

     additional kernel configuration options to get them to work;

     see Documentation/ide.txt.

     Even if support is not available for your interface, you may be

     able to get it to work with the following procedure.  First boot

     MS-DOS and load the appropriate drivers.  Then warm-boot linux

     (i.e., without powering off).  If this works, it can be automated

     by running loadlin from the MS-DOS autoexec.

b. Timeout/IRQ errors.

  - If you always get timeout errors, interrupts from the drive are

    probably not making it to the host.

  - IRQ problems may also be indicated by the message

    `IRQ probe failed ()' while booting.  If  is zero, that

    means that the system did not see an interrupt from the drive when

    it was expecting one (on any feasible IRQ).  If  is negative,

    that means the system saw interrupts on multiple IRQ lines, when

    it was expecting to receive just one from the cdrom drive.

  - Double-check your hardware configuration to make sure that the IRQ

    number of your IDE interface matches what the driver expects.

    (The usual assignments are 14 for the primary (0x170) interface

    and 15 for the secondary (0x1f0) interface.)  Also be sure that

    you don't have some other hardware which might be conflicting with

    the IRQ you're using.  Also check the BIOS setup for your system;

    some have the ability to disable individual IRQ levels, and i've

    had one report of a system which was shipped with IRQ 15 disabled

    by default.

  - Note that many MS-DOS cdrom drivers will still function even if

    there are hardware problems with the interrupt setup; they

    apparently don't use interrupts.

  - If you own a Pioneer DR-A24X, you _will_ get nasty error messages

    on boot such as "irq timeout: status=0x50 { DriveReady SeekComplete }"

    The Pioneer DR-A24X cdrom drives are fairly popular these days.

    Unfortunatly, these drives seem to become very confused when we perform

    the standard Linux ATA disk drive probe. If you own one of these drives,

    you can bypass the ATA probing which confuses these cdrom drives, by

    adding `append="hdX=noprobe hdX=cdrom"' to your lilo.conf file and runing

    lilo (again where X is the drive letter corresponding to where your drive

    is installed (see section 2))

c. System hangups.

  - If the system locks up when you try to access the cdrom, the most

    likely cause is that you have a buggy IDE adapter which doesn't

    properly handle simultaneous transactions on multiple interfaces.

    The most notorious of these is the CMD640B chip.  This problem can

    be worked around by specifying the `serialize' option when

    booting.  Recent kernels should be able to detect the need for

    this automatically in most cases, but the detection is not

    foolproof.  See Documentation/ide.txt for more information

    about the `serialize' option and the CMD640B.

  - Note that many MS-DOS cdrom drivers will work with such buggy

    hardware, apparently because they never attempt to overlap cdrom

    operations with other disk activity.

d. Can't mount a cdrom.

  - If you get errors from mount, it may help to check `dmesg' to see

    if there are any more specific errors from the driver or from the

    filesystem.

  - Make sure there's a cdrom loaded in the drive, and that's it's an

    iso9660 format disc.  You can't mount an audio cd.

  - With the cdrom in the drive and unmounted, try something like

      cat /dev/cdrom | od | more

    If you see a dump, then the drive and driver are probably working

    ok, and the problem is at the filesystem level (i.e., the cdrom is

    not iso9660 format or has errors in the filesystem structure).

  - If you see `not a block device' errors, check that the definitions

    of the device special files are correct.  They should be as

    follows:

      brw-rw----   1 root     disk       3,   0 Nov 11 18:48 /dev/hda

      brw-rw----   1 root     disk       3,  64 Nov 11 18:48 /dev/hdb

      brw-rw----   1 root     disk      22,   0 Nov 11 18:48 /dev/hdc

      brw-rw----   1 root     disk      22,  64 Nov 11 18:48 /dev/hdd

    Some early Slackware releases had these defined incorrectly.  If

    these are wrong, you can remake them by running the script

    scripts/MAKEDEV.ide.  (You may have to make it executable

    with chmod first.)

    If you have a /dev/cdrom symbolic link, check that it is pointing

    to the correct device file.

    If you hear people talking of the devices `hd1a' and `hd1b', these

    were old names for what are now called hdc and hdd.  Those names

    should be considered obsolete.

  - If mount is complaining that the iso9660 filesystem is not

    available, but you know it is (check /proc/filesystems), you

    probably need a newer version of mount.  Early versions would not

    always give meaningful error messages.

e. Directory listings are unpredictably truncated, and `dmesg' shows

   `buffer botch' error messages from the driver.

  - There was a bug in the version of the driver in 1.2.x kernels

    which could cause this.  It was fixed in 1.3.0.  If you can't

    upgrade, you can probably work around the problem by specifying a

    blocksize of 2048 when mounting.  (Note that you won't be able to

    directly execute binaries off the cdrom in that case.)

    If you see this in kernels later than 1.3.0, please report it as a

    bug.

f. Data corruption.

  - Random data corruption was occasionally observed with the Hitachi

    CDR-7730 cdrom. If you experience data corruption, using "hdx=slow"

    as a command line parameter may work around the problem, at the

    expense of low system performance.

6. cdload.c

-----------

/*

 * cdload.c    

 *

 * Load a cdrom from a specified slot in a changer.  The drive should be

 * unmounted before executing this.

 *

 * Based on code originally from Gerhard Zuber .

 */

#include 

#include 

#include 

#include 

#include 

#include 

#include 

int

main (int argc, char **argv)

{

        char *program;

        char *device;

        int x_slot;

        int fd;           /* file descriptor for CD-ROM device */

        int status;       /* return status for system calls */

        program = argv[0];

        if (argc != 3) {

                fprintf (stderr, "usage: %s  \n", program);

                exit (1);

        }

        device = argv[1];

        x_slot = atoi (argv[2]);

        /* open device */

        fd = open (device, 0);

        if (fd < 0) {

                fprintf (stderr, "%s: open failed for `%s': %s\n",

                         program, device, strerror (errno));

                exit (1);

        }

        /* load */

        status = ioctl (fd, CDROM_SELECT_DISC, x_slot);

        if (status != 0) {

                fprintf (stderr,

                         "%s: CDROM_SELECT_DISC ioctl failed for `%s': %s\n",

                         program, device, strerror (errno));

                exit (1);

        }

        /* close device */

        status = close (fd);

        if (status != 0) {

                fprintf (stderr, "%s: close failed for `%s': %s\n",

                         program, device, strerror (errno));

                exit (1);

        }

        exit (0);

}