ATTACH_INTERRUPT_PARAMETERS

RtAttachInterrupt can be used in two different ways: for line-based interrupts or message-based interrupts. Each interrupt type requires filling in a different portion of the ATTACH_INTERRUPT_PARAMETERS structure. The caller identifies which set of input arguments it is providing (and, hence, which portion of the structure has been filled in) by setting the AttachVersion field of the ATTACH_INTERRUPT_PARAMETERS structure to a particular value, as described in the Members section below.

Syntax

typedef struct _ATTACH_INTERRUPT_PARAMETERS {
      ULONG AttachVersion;
      union {
            //Parameters for line-based interrupt
            Struct {
                  PSECURITY_ATTRIBUTES pThreadAttributes;
                  ULONG StackSize;
                  BOOLEAN (RTFCNDCL * PRoutine)(PVOID context);
                  PVOID Context;
                  ULONG Priority;
                  INTERFACE_TYPE InterfaceType;
                  ULONG BusNumber;
                  PCI_SLOT_NUMBER SlotNumber;
                  ULONG BusInterruptLevel;
                  ULONG BusInterruptVector;
                  BOOLEAN Shared;
                  KINTERUPT_MODE InterruptMode;
                  INTERRUPT_DISPOSITION (RTFCNDCL * MyInterrupt)(PVOID context);
                  KAFFINITY ProcessorEnableMask;
            } LineBased;

            //Parameters for message-based interrupt
            Struct {
                  PSECURITY_ATTRIBUTES pThreadAttributes;
                  ULONG StackSize;
                  BOOLEAN (RTFCNDCL * PRoutine)(PVOID context);
                  PVOID Context;
                  ULONG Priority;
                  ULONG BusNumber;
                  PCI_SLOT_NUMBER SlotNumber;
                  INTERRUPT_DISPOSITION (RTFCNDCL * MyInterrupt)(PVOID context);
                  KAFFINITY ProcessorEnableMask;
            } MessageBased;
      };
} ATTACH_INTERRUPT_PARAMETERS, *PATTACH_INTERRUPT_PARAMETERS;

Members

AttachVersion

Specifies the operation to be performed by RtAttachInterrupt:

AttachVersion Value	RtAttachInterrupt Operation
ATTACH_LINE_BASED	Associates an IST and ISR with the device’s line-based interrupts. Use the LineBased member to provide the additional parameters for the operation.
ATTACH_MESSAGE_BASED	Associates an IST and ISR with the device’s message-based interrupts. Use the MessageBased member to provide the additional parameters for the operation. This value can be used by devices that support: MSI only MSI-X only MSI and MSI-X If the device supports both MSI and MSI-X, use of this value will adhere to Windows behavior that the device should default to MSI-X.
ATTACH_MESSAGE_BASED_PREFER_MSI	Associates an IST and ISR with the device’s message-based interrupts. Use the MessageBased member to provide the additional parameters for the operation. This value can be used by devices that support: MSI only MSI-X only MSI and MSI-X If the device supports both MSI and MSI-X, use of this value allows you to specify that the device should default to MSI.
Note: ATTACH_MESSAGE_BASED_PREFER_MSI is not recommended unless an MSI/MSI-X capable device is found not to work correctly when using MSI-X. MSI-X is preferred because it allows for vector masking.

LineBased

Specifies the additional parameters of the operation to be performed by RtAttachInterrupt when AttachVersion has a value of ATTACH_LINE_BASED.

pThreadAttributes (Ignored by RTSS)

A security attributes structure used when the handler thread is created.

StackSize

The number of bytes to allocate for the handler thread's stack. The stack size defaults to the default thread size. See CreateThread.

pRoutine

A pointer to the handler routine to be run by the Interrupt Service Thread (IST). The routine takes a single PVOID Context argument and returns BOOLEAN.

Context

The argument to the handler routines pRoutine and MyInterrupt, cast as a PVOID.

Priority

The thread priority for the handler routine. pRoutine executes in thread context so it can be interrupted by higher priority threads.

InterfaceType

The type of bus interface on which the hardware is located. It can be one of the following types: Isa, or PCIBus. The upper boundary on the bus types supported is always MaximumInterfaceType which is defined in Rtapi.h.

BusNumber

The bus the device is on in a multiple bus environment, with counting starting at zero. Typically, a machine has only one or two of a particular bus type, so this value is either 0 or 1. Note that this value applies to each bus type, so for a system with one ISA bus and one PCI bus, for example, each would have a BusNumber of 0.

SlotNumber

The logical slot number. When PCIBus is specified, this is a PCI_SLOT_NUMBER type value. Otherwise, this value is ignored.

BusInterruptLevel

A bus-specific interrupt level associated with the device.

NOTE: Since RTX uses IST priorities instead of interrupt levels to schedule interrupt handling from multiple devices, BusInterruptLevel should be set to the same value as BusInterruptVector.

BusInterruptVector

A bus-specific interrupt vector associated with the device.

Shared

Specifies whether the caller is prepared to share the interrupt vector. TRUE when sharing is supported, otherwise FALSE.

InterruptMode

Specifies whether the device interrupt is LevelSensitive or Latched.

MyInterrupt

A pointer to a routine to be run by the Interrupt Service Routine (ISR) or NULL to specify no routine. The routine takes a single PVOID Context argument and returns INTERRUPT_DISPOSITION.

ProcessorEnableMask

Specifies the KAFFINITY mask that represents the set of RTSS processors on which the device’s interrupts can occur. See Specifying a Processor Affinity Bitmask for more details. Once an IST has started, it cannot be moved to another processor.

MessageBased

Specifies the additional parameters of the operation to be performed by RtAttachInterrupt when AttachVersion has a value of ATTACH_MESSAGE_BASED or ATTACH_MESSAGE_BASED_PREFER_MSI.

pThreadAttributes

Ignored. A security attributes structure used when the handler thread is created.