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SCSI_PASS_THROUGH structure

The SCSI_PASS_THROUGH structure is used in conjunction with an IOCTL_SCSI_PASS_THROUGH request to instruct the port driver to send an embedded SCSI command to the target device.

Syntax


typedef struct _SCSI_PASS_THROUGH {
  USHORT    Length;
  UCHAR     ScsiStatus;
  UCHAR     PathId;
  UCHAR     TargetId;
  UCHAR     Lun;
  UCHAR     CdbLength;
  UCHAR     SenseInfoLength;
  UCHAR     DataIn;
  ULONG     DataTransferLength;
  ULONG     TimeOutValue;
  ULONG_PTR DataBufferOffset;
  ULONG     SenseInfoOffset;
  UCHAR     Cdb[16];
} SCSI_PASS_THROUGH, *PSCSI_PASS_THROUGH;

Members

Length

Contains the value of sizeof(SCSI_PASS_THROUGH).

ScsiStatus

Reports the SCSI status that was returned by the HBA or the target device.

PathId

Indicates the SCSI port or bus for the request.

TargetId

Indicates the target controller or device on the bus.

Lun

Indicates the logical unit number of the device.

CdbLength

Indicates the size in bytes of the SCSI command descriptor block.

SenseInfoLength

Indicates the size in bytes of the request-sense buffer.

DataIn
Indicates whether the SCSI command will read or write data. This field must have one of three values:

Data Transfer TypeMeaning

SCSI_IOCTL_DATA_IN

Read data from the device.

SCSI_IOCTL_DATA_OUT

Write data to the device.

SCSI_IOCTL_DATA_UNSPECIFIED

No data is transferred.

 

DataTransferLength

Indicates the size in bytes of the data buffer. Many devices transfer chunks of data of predefined length. The value in DataTransferLength must be an integral multiple of this predefined, minimum length that is specified by the device. If an underrun occurs, the miniport driver must update this member to the number of bytes actually transferred.

TimeOutValue

Indicates the interval in seconds that the request can execute before the port driver considers it timed out.

DataBufferOffset

Contains an offset from the beginning of this structure to the data buffer. The offset must respect the data alignment requirements of the device.

SenseInfoOffset

Offset from the beginning of this structure to the request-sense buffer.

Cdb

Specifies the SCSI command descriptor block to be sent to the target device.

Remarks

The SCSI_PASS_THROUGH structure is used with IOCTL_SCSI_PASS_THROUGH, which is a buffered device control request. To bypass buffering in system memory, callers should use IOCTL_SCSI_PASS_THROUGH_DIRECT. When handling an IOCTL_SCSI_PASS_THROUGH_DIRECT request, the system locks down the buffer in user memory and the device accesses this memory directly.

The members of SCSI_PASS_THROUGH correspond roughly to the members of a SCSI_REQUEST_BLOCK structure. The values of the DataIn member correspond to the SCSI_IOCTL_DATA_IN, SCSI_IOCTL_DATA_OUT, and SCSI_IOCTL_DATA_UNSPECIFIED flags assigned to SrbFlags member of SCSI_REQUEST_BLOCK.

Requirements

Header

Ntddscsi.h (include Ntddscsi.h)

See also

IOCTL_SCSI_PASS_THROUGH
IOCTL_SCSI_PASS_THROUGH_DIRECT
SCSI_PASS_THROUGH_DIRECT
SCSI_REQUEST_BLOCK

 

 

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