The important fields of the dsreq structure are shown in Table 5-1. Some of the field values are expanded in the following topics. The sys/dsreq.h file declares macros for access to many of the fields. Use these macros (listed in Table 5-1) in both expressions and assignments in order to insulate your code against future changes.
| Field Name | Macro | Purpose |
|---|---|---|
| ds_flags | FLAGS(dp) | Bits used to determine device driver actions. See "Values for ds_flags". |
| ds_time | TIME(dp) | Timeout value in milliseconds. If the command does not complete, it is ended with an error code. The driver sets a default of 5000 (5 seconds) when this is set to zero. dsopen() initializes it to 10000. |
| ds_private | PRIVATE(dp) | Field for use by the calling program. dsopen() uses this field to point to its "context" data (see "Using dsopen() and dsclose()"). |
| ds_cmdbuf | CMDBUF(dp) | Address of SCSI command string to be sent. |
| ds_cmdlen | CMDLEN(dp) | Length of the SCSI command string. |
| ds_databuf | DATABUF(dp) | Address of a single data buffer. See "Data Transfer Options". |
| ds_datalen | DATALEN(dp) | Length of data buffer. |
| ds_sensebuf | SENSEBUF(dp) | Address to receive sense data after an error. |
| ds_senselen | SENSELEN(dp) | Length of sense buffer in bytes. |
| ds_iovbuf | IOVBUF(dp) | Address of an iov_t structure. See "Data Transfer Options". |
| ds_iovlen | IOVLEN(dp) | Length of data described by ds_iovbuf. |
| ds_link | This field is not supported, and should be zero-filled. | |
| ds_synch | This field is not supported, and should be zero-filled. | |
| ds_revcode | Intended for the version code of the dsreq driver, not currently set to a useful value. | |
| ds_ret | RET(dp) | Return code for the requested operation. See Table 5-3. |
| ds_status | STATUS(dp) | SCSI status byte from the operation. See Table 5-4. |
| ds_msg | MSG(dp) | The first byte of a message returned by the target. See Table 5-5. |
| ds_cmdsent | CMDSENT(dp) | Length of command string actually sent (same as ds_cmdlen, unless an error occurs). |
| ds_datasent | DATASENT(dp) | Length of data transferred. |
| ds_sensesent | SENSESENT(dp) | Length of sense data received. |
The dslib library contains functions to simplify the preparation and execution of a dsreq request; see "Using dslib Functions".