Abstract: An interface unit may comprise a buffer configured to store requests that are to be transmitted on an interconnect and a control unit coupled to the buffer. In one embodiment, the control unit is coupled to receive a retry response from the interconnect during a response phase of a first transaction for a first request stored in the buffer. The control unit is configured to record an identifier supplied on the interconnect with the retry response that identifies a second transaction that is in progress on the interconnect. The control unit is configured to inhibit reinitiation of the first transaction at least until detecting a second transmission of the identifier. In another embodiment, the control unit is configured to assert a retry response during a response phase of a first transaction responsive to a snoop hit of the first transaction on a first request stored in the buffer for which a second transaction is in progress on the interconnect.

Abstract: In one embodiment, an apparatus comprises a first clocked storage device operable in a first clock domain corresponding to a first clock signal. The first clocked storage device has an input coupled to receive one or more bits transmitted on the input from a second clock domain corresponding to a second clock signal. The apparatus further comprises control circuitry configured to ensure that a change in a value of the one or more bits transmitted on the input meets setup and hold time requirements of the first clocked storage device. The control circuitry is responsive to a sample history of one of the first clock signal or the second clock signal to detect a phase relationship between the first clock signal and the second clock signal on each clock cycle to ensure the change meets the setup and hold time requirements.

Abstract: In one embodiment, an apparatus comprises a first interface circuit, a direct memory access (DMA) controller coupled to the first interface circuit, and a host coupled to the DMA controller. The first interface circuit is configured to communicate on an interface according to a protocol. The host comprises at least one address space mapped, at least in part, to a plurality of memory locations in a memory system of the host. The DMA controller is configured to perform DMA transfers between the first interface circuit and the address space, and the DMA controller is further configured to perform DMA transfers between a first plurality of the plurality of memory locations and a second plurality of the plurality of memory locations.

Abstract: In one embodiment, a processor comprises a prefetch unit coupled to a data cache. The prefetch unit is configured to concurrently maintain a plurality of separate, active prefetch streams. Each prefetch stream is either software initiated via execution by the processor of a dedicated prefetch instruction or hardware initiated via detection of a data cache miss by one or more load/store memory operations. The prefetch unit is further configured to generate prefetch requests responsive to the plurality of prefetch streams to prefetch data in to the data cache.

Abstract: In one embodiment, an integrated circuit comprises at least one logic circuit supplied by a first supply voltage and at least one memory circuit coupled to the logic circuit and supplied by a second supply voltage. The memory circuit is configured to be read and written responsive to the logic circuit even if the first supply voltage is less than the second supply voltage during use. In another embodiment, a method comprises a logic circuit reading a memory cell, the logic circuit supplied by a first supply voltage; and the memory cell responding to the read using signals that are referenced to the first supply voltage, wherein the memory cell is supplied with a second supply voltage that is greater than the first supply voltage during use.

Abstract: In one embodiment, a processor comprises a retire unit and a load/store unit coupled thereto. The retire unit is configured to retire a first store memory operation responsive to the first store memory operation having been processed at least to a pipeline stage at which exceptions are reported for the first store memory operation. The load/store unit comprises a queue having a first entry assigned to the first store memory operation. The load/store unit is configured to retain the first store memory operation in the first entry subsequent to retirement of the first store memory operation if the first store memory operation is not complete. The queue may have multiple entries, and more than one store may be retained in the queue after being retired by the retire unit.

Abstract: In one embodiment, a switch is configured to be coupled to an interconnect. The switch comprises a plurality of storage locations and an arbiter control circuit coupled to the plurality of storage locations. The plurality of storage locations are configured to store a plurality of requests transmitted by a plurality of agents. The arbiter control circuit is configured to arbitrate among the plurality of requests stored in the plurality of storage locations. A selected request is the winner of the arbitration, and the switch is configured to transmit the selected request from one of the plurality of storage locations onto the interconnect. In another embodiment, a system comprises a plurality of agents, an interconnect, and the switch coupled to the plurality of agents and the interconnect. In another embodiment, a method is contemplated.

Abstract: In one embodiment, a jitter detector comprises a logic circuit coupled to receive a plurality of inputs indicative of states captured from a plurality of outputs of a delay chain responsive to a first clock input and a plurality of clocked storage devices coupled to the logic circuit. The logic circuit is configured to identify a first input of the plurality of inputs that is: (i) captured in error from a corresponding one of the plurality of outputs of the delay chain, and (ii) the corresponding one of the plurality of outputs of the delay chain is least delayed by the delay chain among the plurality of outputs that are captured in error. The plurality of clocked storage devices are configured to accumulate an indication of which of the plurality of outputs have been captured in error over a plurality of clock cycles of the first clock input.

Abstract: In various embodiments, an apparatus comprises a plurality of agents and an interconnect. In one embodiment, the plurality of agents includes first through fourth agents. The interconnect comprises a plurality of segments that are switchable (e.g. using a plurality of selection circuits) to form communication paths between the agents, and a first segment is included in a first communication path from the first agent to the second agent, and is also included in a second communication path from the third agent to the fourth agent. In another embodiment, each segment is driven by a selection circuit. At least one selection circuit has at least one segment and an output from at least one agent as inputs. In yet another embodiment, an arbiter is configured to determine a communication path on the interconnect for each requesting agent to the destination agent over the segments.

Abstract: In one embodiment, an integrated circuit includes at least one digital leakage detector that includes digital circuitry configured to detect an approximation of a magnitude of the leakage current in transistors of the integrated circuit and configured to generate a digital output representing the approximated magnitude. In another embodiment, a leak detector includes leak circuits and clocked storage devices. Each leak circuit is configured to generate an output signal indicative of a different magnitude of leakage current in a transistor. The clocked storage devices are configured to capture a state representing the output signals of the leak circuits. In another embodiment, a method includes running a test for leakage current in a digital leakage detector, wherein a digital output of the digital leakage detector represents a magnitude of a leakage current being experienced by the integrated circuit during use; and outputting the digital output from the integrated circuit.

Abstract: In one embodiment, a controller comprises one or more transaction queues, one or more age counter circuits, and a control circuit. The transaction queues are configured to store a plurality of transaction requests, each having a transaction type. The age counter circuits are configured to generate one or more age counters, where each age counter corresponds to a respective pair of transaction types. Coupled to receive an indication of an input transaction type corresponding to an input transaction request to the controller and coupled to the age counter circuits, the control circuit is configured to select at least one of the plurality of age counters to be stored with the input transaction request in the one or more transaction queues, each of the selected counters indicative of a relative age of the input transaction request with transaction requests of another transaction type.

Abstract: In one embodiment, an interface unit comprises an address buffer and a control unit coupled to the address buffer. The address buffer is configured to store addresses of processor core requests generated by a processor core and addresses of snoop requests received from an interconnect. The control unit is configured to maintain a plurality of queues, wherein at least a first queue of the plurality of queues is dedicated to snoop requests and at least a second queue of the plurality of queues is dedicated to processor core requests. Responsive to a first snoop request received by the interface unit from the interconnect, the control unit is configured to allocate a first address buffer entry of the address buffer to store the first snoop request and to store a first pointer to the first address buffer entry in the first queue.

Abstract: In one embodiment, a system comprises at least one processor and a peripheral interface controller coupled to the processor. Further coupled to receive transactions from a peripheral interface, the peripheral interface controller is configured to accumulate freed credits for a given transaction type of a plurality of transaction types that are not yet returned to a transmitter on the peripheral interface. The peripheral interface controller is also configured to cause transmission of a flow control update transaction on the peripheral interface responsive to a number of the freed credits exceeding a threshold amount that is less than a total number of credits allocated to the given transaction type.

Abstract: In one embodiment, a processor comprises a prediction circuit and another circuit coupled to the prediction circuit. The prediction circuit is configured to predict whether or not a first load instruction will experience a partial store to load forward (PSTLF) event during execution. A PSTLF event occurs if a plurality of bytes, accessed responsive to the first load instruction during execution, include at least a first byte updated responsive to a previous uncommitted store operation and also include at least a second byte not updated responsive to the previous uncommitted store operation. Coupled to receive the first load instruction, the circuit is configured to generate one or more load operations responsive to the first load instruction. The load operations are to be executed in the processor to execute the first load instruction, and a number of the load operations is dependent on the prediction by the prediction circuit.

Abstract: In one embodiment, a storage circuit comprises a first passgate having an input coupled to receive a signal representing a data input to the storage circuit and further having an output connected to a storage node in the storage circuit. The storage circuit also comprises a scan latch having an input connected to a scan data input to the storage circuit and further coupled to receive a scan enable input. The scan latch is configured to store the scan data input responsive to an assertion of the scan enable input, and also comprises a second passgate connected to the storage node and having an input coupled to receive the stored scan data. Each of the first passgate and the second passgate are coupled to receive respective pairs of control signals to control opening and closing of the passgates, wherein the scan enable signal controls which of the respective pairs of control signals are pulsed.

Abstract: In one embodiment, a renamer comprises a plurality of storage locations and compare circuitry. Each storage location is assigned to a respective renameable resource and is configured to store an identifier corresponding to a youngest instruction operation that writes the respective renameable resource. Coupled to receive an input representing one or more retiring instruction identifiers corresponding to instruction operations that are being retired, the compare circuitry is configured to detect a match between at least a first identifier in a first storage location and one of the retiring identifiers. An encoded form of the identifiers is logically divided into a plurality of fields, and the input comprises a first plurality of bit vectors. Each of the first plurality of bit vectors corresponds to a respective field and includes a bit position for each possible value of the respective field.

Abstract: In one embodiment, an integrated circuit comprises resonance limiter circuits coupled to a power supply connection of the integrated circuit. The resonance limiter circuits are configured to detect oscillation on the power supply connection at a resonant frequency, and to dampen the resonant frequency oscillation responsive to detecting the oscillation. In some embodiments, the resonance limiter circuits may damp oscillation at or above the resonant frequency or approximately the resonant frequency (e.g. somewhat below the resonance frequency). The resonant frequency depends on a package of the integrated circuit. In an embodiment, a resonance limiter circuit comprises a filter and a transistor coupled in parallel with the filter between a power supply connection and a ground connection. The filter is tuned to approximately a resonant frequency (e.g. the lowest resonant frequency) that depends on a package corresponding to an integrated circuit into which the resonance limiter circuit is fabricated.

Abstract: In one embodiment, a processor comprises a scheduler configured to issue a first instruction operation to be executed and an execution core coupled to the scheduler. Configured to execute the first instruction operation, the execution core comprises a plurality of replay sources configured to cause a replay of the first instruction operation responsive to detecting at least one of a plurality of replay cases. The scheduler is configured to inhibit issuance of the first instruction operation subsequent to the replay for a subset of the plurality of replay cases. The scheduler is coupled to receive an acknowledgement indication corresponding to each of the plurality of replay cases in the subset, and is configured to inhibit issuance of the first instruction operation until the acknowledge indication is asserted that corresponds to an identified replay case of the subset.

Abstract: In one embodiment, a processor comprises a buffer and a control unit coupled to the buffer. The buffer is configured to store requests to be transmitted on an interconnect on which the processor is configured to communicate. The buffer is coupled to receive a first uncacheable load request having a first address. The control unit is configured to merge the first uncacheable load request with a second uncacheable load request that is stored in the buffer responsive to a second address of the second load request matching the first address within a granularity. A single transaction on the interconnect is used for both the first and second uncacheable load requests, if merged. Separate transactions on the interconnect are used for each of the first and second uncacheable load requests if not merged.

Abstract: In one embodiment, a processor comprises a retire unit and a load/store unit coupled thereto. The retire unit is configured to retire a first store memory operation responsive to the first store memory operation having been processed at least to a pipeline stage at which exceptions are reported for the first store memory operation. The load/store unit comprises a queue having a first entry assigned to the first store memory operation. The load/store unit is configured to retain the first store memory operation in the first entry subsequent to retirement of the first store memory operation if the first store memory operation is not complete. The queue may have multiple entries, and more than one store may be retained in the queue after being retired by the retire unit.