RapidIO: The Next Generation Communication Fabric For Embedded Application

5.3. MAILBOX STRUCTURES

The RapidIO message transactions describe the packets that are used to communicate between processing elements in a system. The actual transmit and receive buffer structures are not specified by the RapidIO Trade Association. Nor has the RapidIO Trade Association defined standard software API interfaces to the messaging structures. The simplicity of the transactions makes it a trivial programming effort to develop drivers that would interact with the messaging hardware.

The messages will typically be written to and read from buffers in the local memory of the processing elements. Depending on the expected messaging load, different structures may be used to support the use and reuse of the message buffers associated with the transmit and receive hardware. The following sections describe both simple and more complicated approaches to managing the message buffers associated with RapidIO messaging transactions.

The inbound mailbox refers to the hardware associated with the reception of RapidIO messaging transactions. This mailbox will first check the message for errors then will acknowledge the transaction to the transmitter. The mailbox will then place the data associated with the message into buffer memory and signal to the targeted processor that a message has been received. The processor would then retrieve the message data for further processing.

Because a single RapidIO end point might be receiving messages from several other devices, it is useful to ...