Abstract: A system is provided which includes a microprocessor comprising a first processing unit to generate a first output signal and a second processing unit to generate a second output signal, and comparison means, coupled to the microprocessor, to detect whether the first output signal differs from the second output signal.

Abstract: A device is provided which includes a first microprocessor core to generate a first output signal; a second microprocessor core to generate a second output signal; a switching fabric having a first input/output port; and lockstep logic, coupled between the first input/output port of the switching fabric and the first and second microprocessor cores, to detect whether the first output signal differs from the second output signal.

Abstract: Techniques are disclosed, for use in a computer system including a plurality of processing units coupled over a system fabric, to identify a lockstep error associated with a first packet to be transmitted over the system fabric; set a viral indicator in the first packet to indicate the lockstep error; and transmit the modified packet over the system fabric.

Abstract: In one aspect of the present invention, a circuit is provided which implements an instruction set architecture defining a first instruction group, a second instruction group to enter a high-reliability mode of operation, and a third instruction group to enter a non-high-reliability mode of operation. The circuit includes means for causing the circuit to enter the high-reliability mode of operation in response to receiving the second instruction group; means for causing the circuit to enter the non-high-reliability mode of operation in response to receiving the third instruction group; first execution means for executing the first instruction group in the high-reliability mode of operation if the circuit is in the high-reliability mode of operation; and second execution means for executing the first instruction group without in the non-high-reliability mode of operation if the circuit is in the non-high-reliability mode of operation.

Abstract: Microprocessor that includes a mechanism for detecting soft errors. The processor includes an instruction fetch unit for fetching an instruction and an instruction decoder for decoding the instruction. The mechanism for detecting soft errors includes duplication hardware for duplicating the instruction and comparison hardware. The processor further includes a first execution unit for executing the instruction in a first execution cycle and the duplicated instruction in a second execution cycle. The comparison hardware compares the results of the first execution cycle and the results of the second execution cycle. The comparison hardware can include an exception unit for generating an exception (e.g., raising a fault) when the results are not the same. The processor also includes a commit unit for committing one of the results when the results are the same.

Abstract: In one embodiment, a system and a method for verifying lockstep operation pertain to monitoring interface signals, detecting output of a modeled lockstep block, comparing the detected output with an expected output for the lockstep block relative to a current modeled machine state, and flagging a lockstep block error if the detected output does not match the expected output.

Abstract: In one embodiment, a core determinacy verification system and a method pertain to extracting data stored in core model structures, comparing the extracted data of one modeled processor core with extracted data of another modeled processor core, determining if any mismatching data will cause core divergence, and facilitating notice of an error if any mismatching data will cause core divergence.

Abstract: A processor that includes an in-order execution architecture for executing at least two instructions per cycle (e.g., 2n instructions are processed per cycle, where n is an integer greater than or equal to one) and at least two symmetric execution units. The processor includes an instruction fetch unit for fetching n instructions (where n is an integer greater than or equal to one) and an instruction decoder for decoding the n instruction. The error detection mechanism includes duplication hardware for duplicating the n instructions into a first bundle of n instructions and a second bundle of n instructions. A first execution unit for executing the first bundle of instructions in a first execution cycle, and a second symmetric execution unit for executing the second bundle of instructions in the first execution cycle are provided. The error detection mechanism also includes comparison hardware for comparing the results of the first execution unit and the results of the second execution unit.