OPERATION
interrupt from any node on the network. The sender specifies the destination node ID and
user-defined interrupt vector at origination. These unicast network interrupts are named
HUI (Host Unicast Interrupt) events.
In normal operation, network interrupts will not be processed on receipt by the
originating node (e.g., interrupt self function). However, when Interrupt Self is enabled,
network interrupts can be processed (subject to interrupt enables) on the originating node.
Network interrupts (HBI and HUI) may be initiated via PIO accesses (via the appropriate
SW function) or via an interrupt flag (separate chain entry) on DMA write operations.
The HBI and HUI events are stored in a queue located on the GT200 card. HBI and HUI
events are stored in the order of reception. The receiving node saves the source node ID,
interrupt vector, and interrupt type (broadcast with interrupt level or unicast). The queue
provides numerous advantages over a FIFO including: performance, parallel accesses by
multiple threads, elimination of access mechanism to protect critical region, and the
ability to skip queue entries. The devise driver manages access to the queue.
Applications retrieve interrupt information through the software API.
4.2.17 Modes of Operation
The Figure 4-2 shows the modes of operation. The modes shown are configured through
gt_mon.
4.2.17.1 Write-Me-Last Mode
The Write-Me-Last mode of operation allows the originating node to be the last node in
the ring to have the data deposited to its memory. This can be useful for synchronization.
This means that when the host performs a write to the GT200 shared memory, this data is
not immediately written to the host node’s memory, but is first sent to the other nodes on
the network. When the frame returns to the originating node it is written to shared
memory, and is then removed from the network ring.
Therefore, host-originated data written to shared memory travels the ring updating the
GT200 node memories on the ring and, upon returning to the originating node, that node
writes the data to its own shared memory as the last node on the ring. This guarantees that
the data is available on all other nodes, before it is available locally.
WARNING: This mode is not recommended for applications that use duplicate node
IDs or for open-ring topologies.
4.2.17.2 TX Enable
Transmit enable mode allows data to be transmitted to the network. The default
condition is on.
4.2.17.3 RX Enable
Receive enable mode allows data to be received from the network. The default condition
is on.
4.2.17.4 RT Enable
Retransmit mode allows received data to be retransmitted to the network. The default
condition is on.
Copyright 2005 4-6 GT200 Hardware Reference
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