RTEMS 4.5.1-pre3 On-Line Library

Multiprocessing Manager SEND_PACKET

RTEMS C User's Guide

23.3.5: SEND_PACKET

The SEND_PACKET component of the user-provided MPCI layer is called when RTEMS needs to send a packet containing a message to another node. This component should be adhere to the following prototype:

rtems_mpci_entry user_mpci_send_packet(
  rtems_unsigned32       node,
  rtems_packet_prefix  **packet
);

where node is the node number of the destination and packet is the address of a packet which containing a message. If the packet cannot be successfully sent, the fatal error manager should be invoked.

If node is set to zero, the packet is to be broadcasted to all other nodes in the system. Although some MPCI layers will be built upon hardware which support a broadcast mechanism, others may be required to generate a copy of the packet for each node in the system.

Many MPCI layers use the packet_length field of the rtems_packet_prefix portion of the packet to avoid sending unnecessary data. This is especially useful if the media connecting the nodes is relatively slow.

The to_convert field of the MP_packet_prefix portion of the packet indicates how much of the packet (in rtems_unsigned32's) may require conversion in a heterogeneous system.

RTEMS C User's Guide