CD(4) | Device Drivers Manual | CD(4) |
cd
— SCSI and
ATAPI CD-ROM driver
cd* at scsibus? target ? lun ?
cd1 at scsibus0 target 4 lun 0
cd* at atapibus? drive ? flags 0x0000
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.
Any number of CD-ROM devices may be attached to the system regardless of system configuration as all resources are dynamically allocated.
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 structure 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; };
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
CDIOCSETSTEREO
CDIOCSETMUTE
CDIOCSETLEFT
CDIOCSETRIGHT
CDIOCSETDEBUG
CDIOCCLRDEBUG
CDIOCPAUSE
CDIOCRESUME
CDIOCRESET
CDIOCSTART
CDIOCSTOP
CDIOCALLOW
CDIOCPREVENT
CDIOCEJECT
CDIOCLOADUNLOAD
CDIOCCLOSE
DIOCTUR
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).
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 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 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; however, this is not yet under way.
None.
The cd
driver appeared in 386BSD 0.1.
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.
June 23, 2012 | NetBSD 10.99 |