Specifications

Data Structures
1.15 SCSI Class Driver Request Packet (SCDRP)
Table 1–17 (Cont.) Contents of SCSI Class Driver Request Packet
Field Name Contents
SCDRP$L_CMD_BUF_LEN Length of SCSI command buffer.
SCDRP$L_CMD_PTR Address of the SCSI command descriptor block (its length byte) in the SCSI
command buffer allocated by the SCSI port driver. The SCSI class driver
initializes this field.
SCDRP$L_STS_PTR Address of SCSI status byte in the port command buffer. The SCSI class
driver initializes this field.
SCDRP$L_SCSI_FLAGS SCSI flags. The SCSI class and port drivers use the following bits:
SCDRP$V_S0BUF System buffer mapped. A SCSI class driver
sets this bit, before invoking SPI$MAP_
BUFFER, if the data transfer buffer is in
system space (S0).
SCDRP$V_BUFFER_
MAPPED
Data transfer buffer mapped. A SCSI class
driver sets this bit, after invoking SPI$MAP_
BUFFER, to indicate that the data transfer
buffer (either a system or process space
buffer) has been mapped.
SCDRP$V_DISK_SPUN_
UP
START UNIT command issued. The SCSI
disk class sets this bit.
SCDRP$V_LOCK Fork block in use.
SCDRP$V_MREG_DONE Mapping registers are loaded to control this
transfer (set by the port driver).
SCDRP$V_ONEBYTE One byte transfer in progress.
SCDRP$V_QUEUE_FULL Indicates a full queue to port driver when the
port is sending I/O to device.
SCDRP$V_QUEUED_IO Indicates a queued I/O characteristic when
set. Indicates a not-queued I/O and error
recovery when zero.
SCDRP$V_ERROR_REC_
IO
Indicates an error recovery I/O.
SCDRP$L_DATACHECK Address of buffer for datacheck operations. A SCSI class driver maintains
this field.
SCDRP$L_SCSI_STK_PTR Stack pointer of the class driver’s return address stack.
SCDRP$L_SCSI_STK Class driver’s return address stack. This stack is 32 bytes long.
SCDRP$L_CL_RETRY Retry count.
SCDRP$L_DMA_TIMEOUT Maximum number of seconds for a target to change the SCSI bus phase or
complete a data transfer.
Upon sending the last command byte, the port driver waits this many
seconds for the target to change the bus phase lines and assert REQ
(indicating a new phase). Or, if the target enters the DATA IN or DATA
OUT phase, the transfer must be completed within this interval.
A class driver can initialize this field to specify a per-request DMA timeout
value.
SCDRP$L_DISCON_
TIMEOUT
Maximum number of seconds, from the time the initiator receives the
DISCONNECT message, for a target to reselect the initiator so that it can
proceed with the disconnected I/O transfer. A class driver can initialize this
field to specify a per-request disconnect timeout value.
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