Abstract: A method and device for locking a cache line of a cache is disclosed. The method includes automatically changing a state of a cache line from a valid locked state to an invalid locked state in response to receiving an indication that a memory location external to the cache and corresponding to the cache line is associated with an access request by a processor or other data access module. Thus, the locked state of a cache line is maintained even after data in the locked cache line is invalidated. By maintaining the invalid locked state, the cache line is not available for reallocation by the cache. This allows locked cache lines that become invalidated to remain locked without additional software overhead to periodically determine whether the lock has been lost due to invalidation of the cache line.

Abstract: A memory system has a first memory having an array of memory cells that includes a redundant column. The redundant column substitutes for a first column in the array. The first column includes a test memory cell. The array receives a power supply voltage. The test memory cell becomes non-functional at a higher power supply voltage than the memory cells of the array. A memory controller is coupled to the first memory and is for determining if the test memory cell is functional at a first value for the power supply voltage. This is useful in making decisions concerning the value of the power supply voltage applied to the array.

Abstract: A data processing device and methods thereof are disclosed. The data processing device can operate in three different modes. In a first, N-bit mode, the data processing device performs memory accesses based on N-bit values and performs arithmetic operations using N-bit values. In a second, hybrid N-bit/M-bit mode, the data processing device performs memory accesses based on M-bit values, where M is less than N, and performs arithmetic operations using N-bit values. In a third, M-bit mode, the data processing device performs memory accesses based on M-bit values and performs arithmetic operations using M-bit values. The three modes provide for compatibility with a wide range of applications. Further operation in the M-bit mode can provide a power savings when implementing applications compatible with that mode.

Abstract: A memory has bits that fail as power supply voltage is reduced to reduce power and/or increase endurance. The bits become properly functional when the power supply voltage is increased back to its original value. With the reduced voltage, portions of the memory that include non-functional bits are not used. Much of the memory may remain functional and use is retained. When the voltage is increased, the portions of the memory that were not used because of being non-functional due to the reduced power supply voltage may then be used again. This is particularly useful in a cache where the decrease in available memory due to power supply voltage reduction can be implemented as a reduction in the number of ways. Thus, for example an eight way cache can simply be reduced to a four way cache when the power is being reduced or endurance increased.

Abstract: A data processing system having a processor and a target device processes decorated instructions (i.e. an instruction having a decoration value). A device of the data processing system such as the processor sends transactions to the target device over a system interconnect. The transactions include an indication of an instruction operation, an address associated with the instruction operation, a decoration value (i.e. a command to the target device to perform a function in addition to a primary function of the executed instruction), and access permissions associated with the address. The target device (e.g. a memory with functionality in addition to storage functionality) determines whether a decoration operation specified by the decoration value is permissible based on the received access permissions. The target device performs the decoration operation if appropriate permissions exist.

Abstract: A data processing system having a processor and a target device processes decorated instructions (i.e. an instruction having a decoration value). A device of the data processing system such as the processor sends transactions to the target device over a system interconnect. A decorated storage notify (DSN) transaction includes an indication of an instruction operation, an address associated with the instruction operation, and a decoration value (i.e. a command to the target device to perform a function in addition to a store or a load). The transaction on the system interconnect includes an address phase and no data phase, thereby improving system bandwidth. In one form the target device (e.g. a memory with functionality in addition to storage functionality) performs a read-modify-write operation using information at a storage location of the target device.

Abstract: A processing device includes a first storage location configured to store a first value associated with a first address space, a second storage location configured to store a second value associated with a second address space, and a third storage location configured to store a third value associated with a third address space. The processing device further includes a memory management unit, which includes a first input configured to receive a first address value associated with a data transfer operation, a second input configured to receive an identifier associated with the data transfer operation, and an address space select module configured to identify a select value from the first value, the second value and the third value based on the identifier. The memory management module further includes an address modification module configured to generate a second address value based on the first address value and the select value.

Abstract: A data processing system has an interrupt controller which provides an interrupt request along with a corresponding interrupt identifier and a corresponding interrupt vector to a processor. If the processor accepts the interrupt, the processor returns the same interrupt identifier value by way of interrupt identifier, along with interrupt acknowledge, to the interrupt controller. An interrupt taken/not taken indicator may also be provided. The communications interface used to coordinate interrupt processing between the interrupt controller and the processor may be asynchronous.

Abstract: A method for dynamically controlling sense amplifier differential margin of a memory during operation, in an integrated circuit, including a plurality of addressable units, is provided. The method includes setting the sense amplifier differential margin corresponding to the plurality of addressable units to a first value. The method further includes if a read data error occurs when data is read from a set of the plurality of addressable units, then setting the sense amplifier differential margin corresponding to the plurality of addressable units to a second value, wherein the second value is greater than the first value.

Abstract: A method includes providing a debug instruction and providing a debug control register field, where if the debug control register field has a first value, the debug instruction executes a debug operation and where if the debug control register field has a second value, the debug instruction is to be executed as a no-operation (NOP) instruction. A data processing system includes instruction fetch circuitry for receiving a debug instruction, a debug control register field, and debug execution control circuitry for controlling execution of the debug instruction in a first manner if the debug control register field has a first value and in a second manner if the debug control register field has a second value, where in the first manner a debug operation is performed and in the second manner no debug operation is performed.

Abstract: A processor has a fetch unit and a branch execution unit. The fetch unit has a branch predictor. The branch predictor has a branch target buffer and a branch direction predictor. A wake value is a number of instruction fetches that is predicted to be performed after a fetch of a branch. Thus, for a first branch, for example, a first wake number is predicted. A low power mode of the branch predictor is enabled for a duration of the first wake value in response to hit in the branch target buffer in which the hit is in response to the first branch.

Abstract: For use in a data processing system comprising a processor configured to execute a first set of instructions corresponding to a first thread and a second set of instructions corresponding to a second thread, a method is provided. The method comprises in response to execution of a debug instruction by the first thread while executing the first set of instructions, generating a debug event for processing by the second thread.

Abstract: For use in a data processing system comprising a processor configured to execute a first set of instructions corresponding to a first thread and a second set of instructions corresponding to a second thread, a method is provided. The method comprises in response to execution of a debug related instruction by the first thread while executing the first set of instructions, generating a debug event for processing by the second thread, wherein processing the debug event comprises causing a halting operation related to the processor.

Abstract: Test circuitry for determining whether a memory can operate at a lower operating voltage. The test circuitry includes a sense circuit having a delayed sensing characteristic as compared to other sense amplifier circuits of the memory. With this circuitry the test circuitry can determine if the sense circuit can provide valid data under more severe sensing conditions. In one example, the sense circuit includes a delay circuit in the sense enable signal path. If sense circuit can provide data at more server operating conditions, then the memory operating voltage can be lowered.

Abstract: In a data processing system, a marked bit is used to identify a data access instruction throughout the pipeline to indicate that the instruction meets user-specified criteria (e.g., a meets a data address range of interest). Based on the marked bit, an in-order program correlation message is generated which indicates when the data access instruction occurs relative to the instruction stream. The marked bit is also used to generate an in-order data trace message. As a result, the trace streams including only data access instructions meeting user-specified criteria may be post-processed and correlated precisely.

Abstract: A data processing system includes a branch target buffer (BTB) including a plurality of entries, each entry comprising a tag portion and a long branch indicator. The system also includes segment target address storage circuitry which stores a plurality of segment target addresses, index storage circuitry which stores a plurality of indices for indexing into the segment target address storage circuitry, and control circuitry which receives an instruction address and determines whether the instruction address matches a valid entry in the BTB. When the instruction address matches a valid entry in the BTB and the long branch indicator of the valid entry indicates a long branch, the index storage circuitry provides a selected index of the plurality of indices selected by the received instruction address. In response to the selected index, the segment target address storage circuitry provides a selected segment target address as a higher order target address portion.

Abstract: A processor implementation supports selection of an execution mode for debug instruction instances based on respective addresses thereof in addressable memory can provide an attractive mechanism for executing debug instructions in a way that allows some instances of the instructions to operate with debug semantics while suppressing other instances by executing them with no-operation (NOP) semantics. In some embodiments, selection of operative execution semantics may be based on attributes of a memory page in which a particular debug instruction instance resides. In some embodiments, portions of an address space may be delimited (e.g., using values stored in bounding registers and addresses of particular debug instruction instances compared against the delimited portions to select appropriate execution semantics. In some embodiments, both types of evaluations may be used in selecting appropriate execution semantics for a particular debug instruction instance.

Abstract: A thread switch mechanism and technique for a microprocessor is disclosed wherein a processing of a first thread is completed, and a continuation of a second thread is initiated during completion of the first thread. In one form, the technique includes processing a first thread at a pipeline of a processing device, and initiating processing of a second thread at a front end of the pipeline in response to an occurrence of a context switch event. The technique can also include initiating a instruction progress metric in response the context switch event. The technique can further include enabling completion of processing of instructions of the first thread that are at a back end of the pipeline at the occurrence of the context switch event until an expiry of the instruction progress metric.

Abstract: A processor provides memory request and a coherency state value for a coherency granule associated with a memory request. The processor further provides either a first indicator or a second indicator depending on whether the coherency state value represents a cumulative coherency state for a plurality of caches of the processor. The first indicator and the second indicator identify the coherency state value as representing a cumulative coherency state or a potentially non-cumulative coherency state, respectively. If the second indicator is provided, a transaction management module determines whether to request the cumulative coherency state for the coherency granule in response to receiving the second indicator. The transaction management module then provides an indicator of the request for the cumulative coherency state to the processor in response to determining to request the cumulative coherency state.

Abstract: A first thread enters a polling loop to wait for a signal from a second thread before processing instructions dependent on the polling loop. When entering the polling loop, the first thread sets a reservation for a predetermined memory address. The first thread then executes a reservation-based instruction that can change the execution state of the first thread. Reservation circuitry of the processing device that was executing the first thread monitors the reservation. In the event that the reservation cleared, such as by the second thread modifying data at the predetermined memory address, the first thread is reinstated to its prior execution state. By using a hardware reservation mechanism to monitor for clearing of a set reservation, repeated memory accesses to the memory address by the first thread can be minimized or avoided while in the polling loop and other threads can be allowed to execute at the processing device with reduced interference from the waiting thread.