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RS_COMMAND_DESCRIPTOR structure (scsi.h)

  • Article

The RS_COMMAND_DESCRIPTOR structure contains information about a single supported command descriptor block (CDB).

Syntax

typedef struct {
  UCHAR OperationCode;
  UCHAR Reserved;
  UCHAR ServiceAction[2];
  UCHAR Reserved1;
  UCHAR ServiceActionValid : 1;
  UCHAR CommandTimeoutsDescriptorPresent : 1;
  UCHAR CommandDurationLimitPage : 2;
  UCHAR MultipleLogicalUnits : 2;
  UCHAR ReadWriteCommandDurationLimitsPage : 1;
  UCHAR Reserved2 : 1;
  UCHAR CdbLength[2];
} RS_COMMAND_DESCRIPTOR, *PRS_COMMAND_DESCRIPTOR;

Members

OperationCode

Specifies the command being requested by the command descriptor block (CDB).

Reserved

Reserved for internal use.

ServiceAction[2]

Provides qualification for the OperationCode field for some commands, allowing:

  • Unrelated commands that share the same operation code, such as the Report Supported Operation Codes and the Report Target Port Groups commands.
  • A set of related functions that share the same operation code, for example, the Persistent Reserve In command.

Reserved1

Reserved for internal use.

ServiceActionValid

Indicates that the contents of the OperationCode and ServiceAction fields are valid.

CommandTimeoutsDescriptorPresent

Indicates that the command timeouts descriptor is included in this command descriptor.

CommandDurationLimitPage

The ReadWriteCommandDurationLimitsPage and the CommandDurationLimitPage fields together indicate the mode page that specifies the command duration limit for the command.

MultipleLogicalUnits

The MultipleLogicalUnits field is described in the following table.

Value Description
0 The effect of this command on other logical units is not reported.
1 This command only affects this logical unit.
2 This command affects more than one but not all logical units contained in this SCSI target device.
3 This command affects all of the logical units contained in this SCSI target device.

ReadWriteCommandDurationLimitsPage

The ReadWriteCommandDurationLimitsPage and the CommandDurationLimitPage fields together indicate the mode page that specifies the command duration limit for the command.

Reserved2

Reserved for internal use.

CdbLength[2]

Indicates the length of the command descriptor block in bytes for the OperationCode, and if the ServiceActionValid is TRUE, the action indicated by the ServiceAction field.

Remarks

The values for the ReadWriteCommandDurationLimitsPage and the CommandDurationLimitPage fields are reflected in the following table.

ReadWriteCommandDurationLimitsPage CommandDurationLimitPage Description
0 0 No command duration limit mode page is indicated for this command.
1 0 Reserved
0 1 Command duration limit A mode page
0 2 Command duration limit B mode page
1 1 Command duration limit T2A mode page
1 2 Command duration limit T2B mode page
0 or 1 3 Reserved

Requirements

Requirement Value
Header scsi.h