CD(4)                     OpenBSD Programmer's Manual                    CD(4)

NAME
     cd - SCSI CD-ROM driver

SYNOPSIS
     cd* at scsibus? target ? lun ?
     cd1 at scsibus0 target 4 lun 0

DESCRIPTION
     The cd driver provides support for a SCSI CD-ROM (Compact Disc-Read Only
     Memory) drive.  In an attempt to look like a regular disk, the cd driver
     synthesizes a partition table, with one partition covering the entire CD-
     ROM.  It is possible to modify this partition table using disklabel(8),
     but it will only last until the CD-ROM is unmounted.  In general the in-
     terfaces are similar to those described by wd(4) and sd(4).

     As the SCSI adapter is probed during boot, the SCSI bus is scanned for
     devices.  Any devices found which answer as ``Read-only'' type devices
     will be ``attached'' to the cd driver.

     The system utility disklabel(8) may be used to read the synthesized disk
     label structure, which will contain correct figures for the size of the
     CD-ROM should that information be required.

KERNEL CONFIGURATION
     Any number of CD-ROM devices may be attached to the system regardless of
     system configuration as all resources are dynamically allocated.

IOCTLS
     The following ioctl(2) calls which apply to SCSI CD-ROM drives are de-
     fined in the header files <sys/cdio.h> and <sys/disklabel.h>.

     DIOCGDINFO, DIOCSDINFO
             (struct disklabel) Read or write the in-core copy of the diskla-
             bel for the drive.  The disklabel is initialized with information
             read from the SCSI inquiry commands, and should be the same as
             the information printed at boot.  This structure is defined in
             disklabel(5).

     CDIOCPLAYTRACKS
             (struct ioc_play_track) Start audio playback given a track ad-
             dress and length.  The structure is defined as follows:

                   struct ioc_play_track {
                           u_char  start_track;
                           u_char  start_index;
                           u_char  end_track;
                           u_char  end_index;
                   };

     CDIOCPLAYBLOCKS
             (struct ioc_play_blocks) Start audio playback given a block ad-
             dress and length.  The structure is defined as follows:

                   struct ioc_play_blocks {
                           int     blk;
                           int     len;
                   };

     CDIOCPLAYMSF
             (struct ioc_play_msf) Start audio playback given a ``minutes-
             seconds-frames'' address and length.  The structure is defined as
             follows:

                   struct ioc_play_msf {
                           u_char  start_m;
                           u_char  start_s;
                           u_char  start_f;
                           u_char  end_m;
                           u_char  end_s;
                           u_char  end_f;
                   };

     CDIOCREADSUBCHANNEL
             (struct ioc_read_subchannel) Read information from the subchannel
             at the location specified by this structure:

                   struct ioc_read_subchannel {
                           u_char address_format;
                   #define CD_LBA_FORMAT   1
                   #define CD_MSF_FORMAT   2
                           u_char data_format;
                   #define CD_SUBQ_DATA            0
                   #define CD_CURRENT_POSITION     1
                   #define CD_MEDIA_CATALOG        2
                   #define CD_TRACK_INFO           3
                           u_char track;
                           int     data_len;
                           struct  cd_sub_channel_info *data;
                   };

     CDIOREADTOCHEADER
             (struct ioc_toc_header) Return summary information about the
             table of contents for the mounted CD-ROM.  The information is re-
             turned into the following structure:

                   struct ioc_toc_header {
                           u_short len;
                           u_char  starting_track;
                           u_char  ending_track;
                   };

     CDIOREADTOCENTRYS
             (struct ioc_read_toc_entry) Return information from the table of
             contents entries mentioned.  (Yes, this command name is mis-
             spelled.)  The argument structure is defined as follows:

                   struct ioc_read_toc_entry {
                           u_char  address_format;
                           u_char  starting_track;
                           u_short data_len;
                           struct  cd_toc_entry *data;
                   };
             The requested data is written into an area of size data_len and
             pointed to by data.

     CDIOCSETPATCH
             (struct ioc_patch) Attach various audio channels to various out-
             put channels.  The argument structure is defined thusly:

                   struct ioc_patch {
                           u_char  patch[4];
                           /* one for each channel */
                   };

     CDIOCGETVOL, CDIOSETVOL
             (struct ioc_vol) Get (set) information about the volume settings
             of the output channels.  The argument structure is as follows:

                   struct  ioc_vol {
                           u_char  vol[4];
                           /* one for each channel */
                   };

     CDIOCSETMONO
             Patch all output channels to all source channels.

     CDIOCSETSTEREO
             Patch left source channel to the left output channel and the
             right source channel to the right output channel.

     CDIOCSETMUTE
             Mute output without changing the volume settings.

     CDIOCSETLEFT, CDIOCSETRIGHT
             Attach both output channels to the left (right) source channel.

     CDIOCSETDEBUG, CDIOCCLRDEBUG
             Turn on (off) debugging for the appropriate device.

     CDIOCPAUSE, CDIOCRESUME
             Pause (resume) audio play, without resetting the location of the
             read-head.

     CDIOCRESET
             Reset the drive.

     CDIOCSTART, CDIOCSTOP
             Tell the drive to spin-up (-down) the CD-ROM.

     CDIOCALLOW, CDIOCPREVENT
             Tell the drive to allow (prevent) manual ejection of the CD-ROM
             disc.  Not all drives support this feature.

     CDIOCEJECT
             Eject the CD-ROM.

     FIBMAP  Return the physical block number (in 512-byte sectors) given the
             logical block number.  The argument is a pointer to an integer.
             On invocation, it should contain the logical block.  On return,
             it contains the physical block number.

     In addition the general scsi(4) ioctls may be used with the cd driver, if
     used against the `whole disk' partition (i.e., /dev/rcd0c).

NOTES
     When a CD-ROM is changed in a drive controlled by the cd driver, then the
     act of changing the media will invalidate the disklabel and information
     held within the kernel.  To stop corruption, all accesses to the device
     will be discarded until there are no more open file descriptors referenc-
     ing the device.  During this period, all new open attempts will be re-
     jected.  When no more open file descriptors reference the device, the
     first next open will load a new set of parameters (including disklabel)
     for the drive.

     The audio code in the cd driver only supports SCSI-2 standard audio com-
     mands.  Because many CD-ROM manufacturers have not followed the standard,
     there are many CD-ROM drives for which audio will not work.  Some work is
     planned to support some of the more common ``broken'' CD-ROM drives; how-
     ever, this is not yet under way.

FILES
     /dev/cd[0-9][a-h]   block mode CD-ROM devices
     /dev/rcd[0-9][a-h]  raw mode CD-ROM devices

DIAGNOSTICS
     None.

SEE ALSO
     scsi(4), sd(4), disklabel(5), disklabel(8)

HISTORY
     The cd driver appeared in 386BSD 0.1.

BUGS
     The names of the structures used for the third argument to ioctl() were
     poorly chosen, and a number of spelling errors have survived in the names
     of the ioctl() commands.

OpenBSD 3.0                    January 16, 1996                              4
