Abstract: Methods and apparatus for protecting trace data of a remote debug session for a computing system. In one embodiment, a method includes storing trace data received from one or more trace interfaces to a storage location of a target device, where the trace data is generated from execution at the target device, and where the trace data is protected from an unauthorized access. The method continues with transmitting the trace data to a debug host computer with encryption through a communication channel between the target device and the debug host computer.

Abstract: Methods and apparatus for protecting trace data of a remote debug session for a computing system. In one embodiment, a method includes storing trace data received from one or more trace interfaces to a storage location of a target device, where the trace data is generated from execution at the target device, and where the trace data is protected from an unauthorized access. The method continues with transmitting the trace data to a debug host computer with encryption through a communication channel between the target device and the debug host computer.

Abstract: An apparatus for communicating between lock step is incorporated on two or more processors operating in a lock step mode. Each of the processors includes processor logic to execute a code sequence, and an identical code sequence is executed by the processor logic. The apparatus further includes a processor-specific resource referenced by the code sequence. A multiplexer is coupled to the processor-specific resource, and is controlled to read data based on the identification. Coupled to the processors is a lock step logic block operable to read and compare the output of each of the processors. The lock step logic determines if operation of the processors is in a lock step mode or in an independent processor mode. Such determination may be made by the lock step logic turning off, for example.

Abstract: An apparatus, and a corresponding method, are used for seeding differences in lock stepped processors, the apparatus implemented on two or more processors operating in a lock step mode. Each of the two or more processors comprise a processor-specific resource operable to seed the differences, a processor logic to execute a code sequence, in which an identical code sequence is executed by the processor logic of each of the two or more processors, and an output to provide a result of execution of the code sequence. The processor outputs, based on execution of the code sequence is provided to a lock step logic operable to read and compare the output of each of the two or more processors.

Abstract: An apparatus, operating on an advanced multi-core processor architecture, and a corresponding method, are used to enhance recovery from loss of lock step in a multi-processor computer system. The apparatus for recovery from loss of lock step includes multiple processor units operating in the computer system, each of the processor units having at least two processor units operating in lock step, and at least one idle processor unit operating in lock step; and a controller coupled to the two processor units operating in lock step and the idle processor unit. The controller includes mechanisms for copying an architected state of each of the two lock step processor units to the idle processor unit.

Abstract: The present invention is a method for implementing two architectures on a single chip. The method uses a fetch engine to retrieve instructions. If the instructions are macroinstructions, then it decodes the macroinstructions into microinstructions, and then bundles those microinstructions using a bundler, within an emulation engine. The bundles are issued in parallel and dispatched to the execution engine and contain pre-decode bits so that the execution engine treats them as microinstructions. Before being transferred to the execution engine, the instructions may be held in a buffer. The method also selects between bundled microinstructions from the emulation engine and native microinstructions coming directly from the fetch engine, by using a multiplexer or other means. Both native microinstructions and bundled microinstructions may be held in the buffer. The method also sends additional information to the execution engine.

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: 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: 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 in the non-high-reliability mode of operation if the circuit is in the non-high-reliability mode of operation.

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: An apparatus for communicating between lock step is incorporated on two or more processors operating in a lock step mode. Each of the processors includes processor logic to execute a code sequence, and an identical code sequence is executed by the processor logic. The apparatus further includes a processor-specific resource referenced by the code sequence. A multiplexer is coupled to the processor-specific resource, and is controlled to read data based on the identification. Coupled to the processors is a lock step logic block operable to read and compare the output of each of the processors. The lock step logic determines if operation of the processors is in a lock step mode or in an independent processor mode. Such determination may be made by the lock step logic turning off, for example.

Abstract: An apparatus verifies the correctness of a behavioral model of a microcode machine, where the microcode machine is operable in a native state and an emulated state. The apparatus includes means for producing the native state, means for producing the emulated state, and means for comparing the native state and the emulated state. Corresponding to the apparatus, a method verifies the correctness of a processor behavioral model, where the processor operates in a native mode state and an emulated mode state. The method includes determining if a macroinstruction to be executed is a native instruction, and, if the macroinstruction is a native instruction, executing the native instruction, the execution producing the native mode state of the processor.

Abstract: Parity and mask bit(s) are stored in a random access memory (RAM) that is coupled to a CAM. This CAM may be part of a TLB. The parity and mask bits(s) are stored in conjunction with the CAM entry write. Upon a CAM query match, the reference parity bit(s) and mask bit(s) stored at the address output by the CAM are output from the RAM. These reference parity bit(s) are compared to parity bit(s) generated from a query data value that is masked by the retrieved mask bit(s). In the absence of a CAM or RAM bit error, the reference parity bit(s) from the RAM and the parity bit(s) generated from the masked query data will match. If a CAM or RAM bit error occurred, these two sets of parity bit(s) will not match and thus an error will be detected. This error may be used as an indication that a false CAM match has occurred.

Abstract: An apparatus, operating on an advanced multi-core processor architecture, and a corresponding method, are used to enhance recovery from loss of lock step in a multi-processor computer system. The apparatus for recovery from loss of lock step includes multiple processor units operating in the computer system, each of the processor units having at least two processor units operating in lock step, and at least one idle processor unit operating in lock step; and a controller coupled to the two processor units operating in lock step and the idle processor unit. The controller includes mechanisms for copying an architected state of each of the two lock step processor units to the idle processor unit.

Abstract: An apparatus, and a corresponding method, are used for seeding differences in lock stepped processors, the apparatus implemented on two or more processors operating in a lock step mode, wherein each of the two or more processors comprise a processor-specific resource operable to seed the differences, a processor logic to execute a code sequence, wherein an identical code sequence is executed by the processor logic of each of the two or more processors, and an output to provide a result of execution of the code sequence. The processor outputs, based on execution of the code sequence is provided to a lock step logic operable to read and compare the output of each of the two or more processors.

Abstract: The present invention is a method for processing instructions by decomposing a macroinstruction into at least two microinstructions, executing the microinstructions in parallel, and linking the microinstructions such that they appear as though they were executed as a single functional unit. The present invention operates by determining whether certain exceptions occur in either of the functional units, according to SSE rules for exceptions. If an exception does occur in any of the linked microinstructions, then the execution of each of those microinstructions is canceled. This avoids the necessity of a back-off or undo mechanism.

Abstract: An apparatus and method for efficiently generating arithmetic flags in a computer system. The system includes an eflags register to stored partially computed flags computed by an arithmetic logic unit. The stored partial flags are computed in one cycle. The stored flags are decoded by one of two consuming instructions, PRODF or TBIT, in a second cycle.

Abstract: A method and apparatus are provided for improving the rate at which macroinstructions are transformed into corresponding microinstructions. Encoding is added to a microcode storage device. The encoding indicates that a microinstruction flow will end in a determined number of cycles. The number of cycles is determined by the number of canceled instructions in a processing pipeline that would be introduced if no flow length prediction was used. For flow lengths less than a determined number of cycles, a hint bit is used in an entry point structure. For flow lengths greater than a determined length, a hint bit is encoded at a third line from an end of the microinstruction flow. Using this method, flows of any length can be hinted. Furthermore, flows that do not originate from the entry point structure can also be hinted. The method reduces the number of hint bits that are needed in the entry point structure and provides for better prediction.

Abstract: A method and apparatus that utilizes a simple test and flush mechanism to implement branch instructions of one Instruction Set Architecture (ISA) using instructions of another ISA is described. During the decoding and sequencing of microinstructions to implement a branch instruction, a fix-up address, which represents the remedial branch target in the event of a mispredicted target or branch condition, is determined and stored. A test condition is set to determine if the prediction or the branch condition was correct. When the test condition fails, the instruction execution pipeline is immediately flushed to avoid executing any instruction remaining in the pipeline following the branch instructions. The flushing of the pipeline signals the instruction fetch control mechanism to redirect the instruction flow to the instruction corresponding to the fix-up address.

Abstract: An apparatus, and a corresponding method, are used for seeding differences in lock stepped processors, the apparatus implemented on two or more processors operating in a lock step mode, wherein each of the two or more processors comprise a processor-specific resource operable to seed the differences, a processor logic to execute a code sequence, wherein an identical code sequence is executed by the processor logic of each of the two or more processors, and an output to provide a result of execution of the code sequence. The processor outputs, based on execution of the code sequence is provided to a lock step logic operable to read and compare the output of each of the two or more processors.