Method and system for structured DMA transactions

A computer-readable storage medium having computer-executable instructions for performing a method for structuring at least a first direct memory access (DMA) transaction, the method comprising:

• creating an instance of a DMA enabler object storing operational parameters supported by a device and comprising computer-executable instructions for controlling DMA operations for the device, the instance of the DMA enabler object including a container for a DMA adapter object with respect to the device;
• initializing data in the instance of the DMA enabler object, the data specifying a profile of the device, the specified profile indicating DMA features supported by the device, the indicated DMA features supported by the device comprising at least one of whether scatter/gather DMA operations are supported, a type of addressing supported, and whether duplex operations are supported;
• in response to an input/output request involving the device, creating a first instance of a DMA transaction object having computer-executable instructions for processing the first DMA transaction with respect to the device, the creating a first instance of a DMA transaction object comprising referencing the instance of the DMA enabler object from the first instance of the DMA transaction object, the instance of the DMA enabler object storing operational parameters supported by the device to perform the first DMA transaction;
• initializing first data in the first instance of the DMA transaction object;
• and
• processing the first DMA transaction to completion in conjunction with transitioning the instance of the first DMA transaction object through processing states, wherein:
• the DMA enabler object and the DMA transaction object are object-oriented programming constructs, and
• the first instance of the DMA transaction object maintains state and status information during the processing of the first DMA transaction with respect to the device.

A system for structuring at least a first direct memory access (DMA) transaction in a computing environment, the system comprising:

• an operating system configured for sending an input/output request for the first DMA transaction to a device manager;
• and
• a device manager configured for:
• creating an instance of a DMA enabler object for a device, the DMA enabler object being a first one of a plurality of object-oriented programming constructs, the instance of the DMA enabler object comprising computer-executable instructions for controlling DMA operations indicated as being supported by the device,
• initializing data in the instance of the DMA enabler object, the data specifying a profile of the device, the specified profile indicating DMA features supported by the device, the indicated DMA features supported by the device comprising at least one of whether scatter/gather DMA operations are supported, a type of addressing supported, and whether duplex operations are supported,
• receiving the input/output request, for creating a first instance of a DMA transaction object that maintains a processing state of the first DMA transaction with respect to the device, for initializing first data in the first instance of the DMA transaction object, the first instance of the DMA transaction object referencing the instance of the DMA enabler object after the initializing of the data in the first instance of the DMA transaction object, and
• processing the first DMA transaction to completion in conjunction with transitioning the first instance of the DMA transaction object through processing states;
• and
• a processor to execute a plurality of software modules, the plurality of software modules comprising the operating system, wherein:
• the first instance of the DMA transaction object is in a first state after the initializing and before starting the processing, is in a second state during processing, and transitions to a third state after completion of processing, wherein
• the DMA transaction object is a second one of the plurality of object-oriented programming constructs.

In a computing environment, a method for preparing the computing environment for structuring a direct memory access (DMA) transaction, the method comprising:

• employing a processor executing computer-executable code stored in a memory to implement the following acts using object-oriented programming constructs including a DMA enabler object and a DMA transaction object:
• creating an instance of the DMA enabler object for a device, the instance of the DMA enabler object including a container for a DMA adapter object with respect to the device;
• initializing data in the instance of the DMA enabler object, the data specifying a profile from a profile pool, the specified profile indicating DMA features supported by the device, the indicated DMA features supported by the device comprising at least one of whether scatter/gather DMA operations are supported, a type of addressing supported, and whether duplex operations are supported;
• creating a first instance of the DMA transaction object for maintaining state and status information of a first DMA transaction with respect to the device, the first instance of the DMA transaction object having computer-executable instructions for processing a first DMA transaction with respect to the device;
• and
• initializing first data in the first instance of the DMA transaction object, the first instance of the DMA transaction object referencing the instance of the DMA enabler object after the initializing first data in the instance of the DMA transaction object.

A computer-readable storage medium having computer-executable instructions for performing a method for preparing a computing environment for structuring a direct memory access (DMA) transaction, the method comprising:

• creating an instance of a DMA enabler object for a device, the instance of the DMA enabler object including a container for a DMA adapter object with respect to the device, the DMA enabler object being a first one of a plurality of object-oriented programming constructs, the instance of the DMA enabler object comprising computer-executable instructions for controlling DMA operations indicated to be supported for the device;
• and
• initializing data in the instance of the DMA enabler object, the data specifying a profile of the device, the specified profile indicating DMA features supported by the device, the indicated DMA features supported by the device comprising at least one of whether scatter/gather DMA operations are supported, a type of addressing supported, and whether duplex operations are supported;
• and
• initializing first data in a previously used instance of a DMA transaction object, the DMA transaction object being a second one of the plurality of object-oriented programming constructs, the instance of the DMA transaction object referencing the instance of the DMA enabler object after the initializing first data in the previously used instance of the DMA transaction object.