Abstract: In an advanced multi-core processor architecture, an apparatus and corresponding method, are used to test lock step performance. The apparatus is implemented 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 of each of the two or more processors. A processor-specific resource is referenced by the code sequence, and a state machine asserts a signal based on the occurrence of a programmable event. The apparatus includes an output to provide the asserted signal; and a lock step logic block operates to read and compare the output of each of the more processors. The apparatus may be used to repeatedly and deterministically provide errors that may lead to a loss of lock step.

Abstract: A processor based computer system having dependency checking logic and a register stack, wherein the system overrides the dependency logic such that move instructions associated with the stack registers may be executed in parallel. The system operates such that it can be determined whether a stack underflow exception has occurred and if it has, the move instructions can be flushed, and a micro-code handler algorithm invoked that operates to allow execution of the move instructions in parallel without a stack underflow exception.

Abstract: An apparatus, and a corresponding method, are used for testing a computer microarchitecture. The apparatus includes means for providing reprogrammed microcode. The means for providing the reprogrammed microcode includes means for reprogramming microcode, and means for storing reprogrammed microcode. The storing means includes microcode related to one or more macroinstructions, and reprogrammed test microcode for testing the computer microarchitecture, where the reprogrammed test microcode includes a sequence of microinstructions executed to test the computer microarchitecture. Finally, the apparatus includes means for sequencing the sequence of microinstructions and producing an address for the reprogrammed test microcode.

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: A rare-event injector for generating events in an integrated circuit has circuitry for generating a pseudorandom sequence of events. This pseudorandom sequence of events is injected into circuitry of the integrated circuit to stimulate error handling and recovery circuitry of the integrated circuit.

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: 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: Parity 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 bits(s) are stored in conjunction with the CAM entry write. Upon a CAM query match, the reference parity 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 the query data value. 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 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: Methods for emulating an instruction set extension, comprising providing data to be operated upon, executing a first instruction with respect to a first portion of the data without committing the results of the first executed instruction, if no unmasked exceptions occur with respect to the first portion of the data, executing a second instruction with respect to a second portion of the data, and if no unmasked exceptions occur with respect to the second portion of the data, committing the results of the second executed instruction and again executing the first instruction with respect to the first portion of the data. If the first instruction is executed again, its results are committed. A handler is invoked if an unmasked exception occurs.

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 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: A processor based computer system having dependency checking logic and a register stack, wherein the system overrides the dependency logic such that move instructions associated with the stack registers may be executed in parallel. The system operates such that it can be determined whether a stack underflow exception has occurred and if it has, the move instructions can be flushed, and a micro-code handler algorithm invoked that operates to allow execution of the move instructions in parallel without a stack underflow exception.

Abstract: An apparatus and a method of testing computer microarchitectures has a test writer create a test sequence written directly in microinstructions (both native-mode and emulation-only microinstructions). The microinstruction sequence is then inserted into a reprogrammable microcode storage, replacing the normal sequence of microinstructions for a given macroinstruction. In order to execute the microinstructions, the test writer can issue the macroinstruction. The method may be implemented in a simulation model where one set of microinstructions in the reprogrammable microcode storage can be easily replaced. The method may also be applied to an actual microprocessor implementation.

Abstract: A method and an apparatus checks the fine-grain correctness of a microcode machine central processor unit (CPU) behavioral model. Macroinstructions are decomposed into microinstructions and each microinstruction is executed sequentially. A sequence of microinstructions is determined by an emulated microinstruction sequencer, using dynamic execution information, including information from execution of prior microinstructions in the sequence of microinstructions. At the end of execution of each microinstruction, a reference state is compared to a corresponding state of the behavioral model, and any differences are noted. After execution of all microinstructions in the microinstruction sequence, a reference state is compared to a corresponding state of the behavioral model, and any differences are noted.

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 multiplexor 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: A method and an apparatus for re-creating a trace of instructions from an emulated instruction set when running on hardware optimized for a different instruction set, such as IA-32 instructions running on an IA-64 machine, are disclosed. An execution trace buffer is created that maintains desired information about instructions as they are executed and retired. The invention may be configured such that certain desired information helpful to debugging the system may be written to the buffer as the instructions are retired. This information may include the addresses of sequential or branch instructions, or other relevant information that can be gathered continuously and non-intrusively as instructions are executed. The information may be read from the buffer and output in a machine-visible form at the user's convenience.

Abstract: An apparatus and method for determining register dependency in multiple architecture system. The system includes a microprocessor emulating an emulated instruction set using a native instruction set where the microprocessor contains at least one register. An execution engine provides the native instructions where each native instruction contains at least one register identifier. Flags are provided to each native instruction where each flag indicates whether a register identifier is valid. A bundler checks for dependency among the valid register identifiers in the native instructions.