This Figure is a flowchart for egress transaction handling.
ECAM write and I/O write transactions are non-posted in the PCIe domain. Non-posted transactions must not be allowed to stall posted transactions to avoid deadlock conditions. These non-posted writes require arbitration for a PCIe tag and completion handling resources managed by the bridge's reorder queue. These non-posted writes are not queued in reorder queue and instead are queued into an additional non-posted write FIFO.