CD(4)							   BSD Kernel Interfaces Manual 						     CD(4)

NAME

     cd -- SCSI and ATAPI CD-ROM driver

SYNOPSIS

     cd* at scsibus? target ? lun ?
     cd1 at scsibus0 target 4 lun 0
     cd* at atapibus? drive ? flags 0x0000

DESCRIPTION

     The cd driver provides support for a Small Computer Systems Interface (SCSI) bus and Advanced Technology Attachment Packet Interface (ATAPI)
     Compact Disc-Read Only Memory (CD-ROM) 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 interfaces 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.

     For the use of flags with ATAPI devices, see wd(4).

     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 defined in the header files <sys/cdio.h> and <sys/disklabel.h>.

     DIOCGDINFO

     DIOCSDINFO 	  (struct disklabel) Read or write the in-core copy of the disklabel 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 struc-
			  ture is defined in disklabel(5).

     CDIOCPLAYTRACKS	  (struct ioc_play_track) Start audio playback given a track address 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 address 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 returned 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
			  misspelled).	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 output channels.	The argument structure is defined thusly:

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

     CDIOCGETVOL

     CDIOCSETVOL	  (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.

     CDIOCLOADUNLOAD	  Cause the ATAPI changer to load or unload discs.

     CDIOCCLOSE 	  Tell the drive to close its door and load the media.	Not all drives support this feature.

     In addition the general scsi(4) ioctls may be used with the cd driver, if used against the `whole disk' partition (i.e.  /dev/rcd0d for the
     bebox and i386 port, /dev/rcd0c for all other ports).

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 infor-
     mation held within the kernel.  To stop corruption, all accesses to the device will be discarded until there are no more open file descrip-
     tors referencing the device.  During this period, all new open attempts will be rejected.	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 support SCSI-2 standard audio commands.  Because many CD-ROM manufacturers have not followed the stan-
     dard, 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; however, 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

     intro(4), scsi(4), sd(4), wd(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.

BSD
								 January 16, 1996							       BSD