SYSTEM FOR DETERMINING WHETHER A SUBSEQUENT TRANSACTION MAY BE ALLOWED OR MUST BE ALLOWED OR MUST NOT BE ALLOWED TO BYPASS A PRECEDING TRANSACTION

An apparatus and method for mediating a sequence of transactions across a fabric in a data processing system are implemented. A fabric bridge orders a preceding transaction and a subsequent transaction according to a predetermined protocol. Using the protocol a determination is made whether the subsequent transaction may be allowed to bypass the previous transaction, must be allowed to bypass the previous transaction, or must not be allowed to bypass the preceding transaction. Transactions include load/store (L/S) system memory and L/S to input/output (I/O) device, and direct memory access (DMA) to system memory and DMA peer-to-peer transactions.