Manual Pages  — CD

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

struct ioc_play_blocks
{
        int     blk;
        int     len;
};

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;
};

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;
};

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

struct ioc_read_toc_entry {
        u_char  address_format;
        u_char  starting_track;
        u_short data_len;
        struct  cd_toc_entry *data;
};

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

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

This variable determines how many times the cd driver will retry a READ or WRITE command. This does not affect the number of retries used during probe time or for the cd driver dump routine. This value currently defaults to 4.

The cd driver attempts to automatically determine whether the drive it is talking to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations. Many SCSI drives only support 6 byte commands, and ATAPI drives only support 10 byte commands. The cd driver first attempts to determine whether the protocol in use typically supports 6 byte commands by issuing a CAM Path Inquiry CCB. It will then default to 6 byte or 10 byte commands as appropriate. After that, the cd driver defaults to using 6 byte commands (assuming the protocol the drive speaks claims to support 6 byte commands), until one fails with a SCSI ILLEGAL REQUEST error. Then it tries the 10 byte version of the command to see if that works instead. Users can change the default via per-drive sysctl variables and loader tunables. Where "%d" is the unit number of the drive in question. Valid minimum command sizes are 6 and 10. Any value above 6 will be rounded to 10, and any value below 6 will be rounded to 6.