A resilient system implementation in a network-on-ship with at least one functional logic unit and at least one duplicated logic unit. A resilient system and method, in accordance with the invention, are disclosed for detecting a fault or an uncorrectable error and isolating the fault. Isolation of the fault prevents further propagation of the fault throughout the system. The resilient system includes isolation logic or an isolation unit that isolates the fault.

A data processing system and methods for operating the same are disclosed. The method includes detecting a fault by comparing output signals from a first processing core and a second processing core, entering a safe mode based upon detecting the fault, completing transactions while in the safe mode, and determining whether the fault corresponds to a hard error. Based upon the fault corresponding to a hard error, one of processing cores is identified as a faulty core. The faulty core is inhibited from executing instructions and the other processing core is allowed to execute instructions.

A method for synchronizing processor units. An external synchronizer is communicated with to determine whether an undesired amount of skew is present between a first processor unit and a second processor unit in communication with a synchronization system. The first processor unit is selectively directed to perform an action without generating a needed result such that the undesired amount of skew between the first processor unit and the second processor unit is reduced when the undesired amount of skew is present in the first processor unit. The first processor unit and the second processor unit are associated with each other for a high integrity mode in which integrity checks are performed on corresponding messages generated by the first processor unit and the second processor unit.

A method to check for redundancy in two or more data lines comprises receiving data on a first data line, computing a first cyclic redundancy check (CRC) value on the data of the first data line, performing an exclusive OR (XOR) function on the first CRC value with a stored memory value, and updating the stored memory value with a result of the XOR function, and repeating on additional data lines until a last line is processed such that an error is indicated if a final stored memory value is not zero. An apparatus to check that two cores are operating in lockstep comprises a first core comprising a first data checker, a second core comprising a second data checker, and a lockstep checker to compare an output of the first data checker with an output of the second data checker.

In a data processing device including two sets of circuit pairs which are respectively duplicated in two clock domains which are asynchronous to each other, an asynchronous transfer circuit that transfers a payload signal is provided between the two sets of circuit pairs. The asynchronous transfer circuit includes two sets of a pair of bridge circuits which are respectively connected to the two sets of circuit pairs, and asynchronously transfers the payload signal and a control signal indicating a timing at which the payload signal is stable on a reception side. The two sets of a pair of bridge circuits and the payload signals can be duplicated, but the control signal is not duplicated, and the received payload signal is used for timing control to supply an expected same time difference, to the pair of duplicated circuits. This enables asynchronous transfer between circuits duplicated in the asynchronous clock domains.

An apparatus (2) has first processing circuitry (6) and second processing circuitry (4). The second processing circuitry 4 has at least one hardware mechanism (10), (30) providing a greater level of fault protection or fault detection than is provided for the first processing circuitry (6). Coherency control circuitry (45, 80, 82) controls access to data from at least part of a shared address space by the first and second processing circuitry (6, 4) according to an asymmetric coherency protocol in which a local-only update of data in a local cache (8) of the first processing circuitry (6) is restricted in comparison to a local-only update of data in a local cache (8) of the second processing circuitry (4).

A system and method enables loosely-coupled lock-step computing including sensors that detect or measure a physical property and server groups. Each server group is serially linked to another server group and includes server instances operating in virtual synchrony. Virtual synchrony middleware receives outputs from multiple server instances and renders a single reply based on the outputs from the multiple server instances. The virtual synchrony middleware replicates and orders incoming requests to the server groups to ensure each of the server instances of that server group receives the same incoming requests in the same order.

A distributed system implementation for cache coherence comprises distinct agent interface units, coherency controllers, and memory interface units. The agents send requests in the form of read and write transactions. The system also includes a memory that includes coherent memory regions. The memory is in communication with the agents. The system includes a coherent interconnect in communication with the memory and the agents. The system includes a second identical coherent interconnect in communication with the memory and the agents. The system also includes a comparator for comparing at least two inputs, the comparator is in communication with the two coherent interconnects

A distributed system implementation for cache coherence comprises distinct agent interface units, coherency controllers, and memory interface units. The agents send requests in the form of read and write transactions. The system also includes a memory that includes coherent memory regions. The memory is in communication with the agents. The system includes a coherent interconnect in communication with the memory and the agents. The system includes a second identical coherent interconnect in communication with the memory and the agents. The system also includes a comparator for comparing at least two inputs, the comparator is in communication with the two coherent interconnects.

A distributed system implementation for cache coherence comprises distinct agent interface units, coherency controllers, and memory interface units. The agents send requests in the form of read and write transactions. The system also includes a memory that includes coherent memory regions. The memory is in communication with the agents. The system includes a coherent interconnect in communication with the memory and the agents. The system includes a second identical coherent interconnect in communication with the memory and the agents. The system also includes a comparator for comparing at least two inputs, the comparator is in communication with the two coherent interconnects