Abstract: An in-vehicle communication device for transmitting and receiving a signal by a predetermined communication protocol related to Ethernet® (registered trademark), the in-vehicle communication device comprising: a control circuit configured to generate transmission data including interrupt data inserted into an inter-frame gap between Ethernet frames; and a PHY unit having a communication circuit configured to convert the transmission data generated by the control circuit into a signal and transmit the signal.

Abstract: In an embodiment a system on chip includes a plurality of microprocessors, a plurality of slave resources, an interconnection circuit coupled between the microprocessors and the slave resources, the interconnection circuit configured to route transactions between the microprocessors and the slave resources and a processing controller configured to allow a user of the system to implement within the system at least one configuration diagram of the system defined by a set of configuration pieces of information used to define an assignment of at least one microprocessor to at least some of the slave resources, select the at least one microprocessors, and authorise an external debugging tool to access, for debugging purposes, only the slave resources assigned to the at least one microprocessor.

Abstract: A method to build a persistent memory (PM)-based data storage system without involving a processor (CPU) at storage nodes is disclosed which includes storing data in one or more storage nodes that only include PM and no CPUs, with data stored in PM in form of link lists, accessing data stored in the one or more storage nodes' PM directly by remote compute nodes through a network, maintaining metadata associated with the data by one or more global controllers (metadata servers), upon request by a user to read or write data, the compute nodes contacting the one or more metadata servers to obtain location of data of interest in form of pointers (shortcuts), and the compute nodes sending network requests directly to the one or more storage nodes' PM to locate latest version of data by tracing the link list from the associated shortcut to corresponding tails.

Abstract: A machine implemented method for prioritizing system interrupts in a processing system is provided. The method comprising: determining, at a supervisor module, for each interrupt, a relative interrupt priority in accordance with at least one interrupt parameter for said interrupt; prioritising, at said supervisor module, each said interrupt with respect to other interrupts of said system in compliance with said determined relative interrupt priority; and in response to a change to said at least one interrupt parameter during operation of said system, adjusting said determined relative interrupt priority, and re-prioritising each said interrupt with respect to said other interrupts of said system in compliance with said adjusted relative interrupt priority.

Abstract: A multi-core processor system includes a given configured to queue an interrupt process of a software interrupt request to the given core, and execute queued processes in the order of queuing at the given core; execute preferentially an interrupt process of a hardware interrupt request to the given core over a process under execution at the given core; determine whether the software interrupt request is a specific software interrupt request; and perform control to preferentially execute the interrupt process without queuing, upon determining that the software interrupt request is the specific software interrupt request.

Abstract: A method of balancing input/output (I/O) device interrupt service loading in a computer system comprises: assigning priorities to a plurality of I/O device interrupts of a processing unit of the computer system; servicing the plurality of interrupts according to the assigned priorities thereof; collecting data on the interrupt servicing of the plurality of interrupts over a time interval; reassigning the priorities of the plurality of interrupts based on the collected interrupt service data; and repeating the collecting and reassigning steps to balance input/output (I/O) device interrupt service loading of the processing unit.

Abstract: Embodiments of processors, methods, and systems for virtualizing interrupt prioritization and delivery are disclosed. In one embodiment, a processor includes instruction hardware and execution hardware. The instruction hardware is to receive a plurality of instructions, including a first instruction to transfer the processor from a root mode to a non-root mode for executing guest software in a virtual machine, wherein the processor is to return to the root mode upon the detection of any of a plurality of virtual machine exit events. The execution hardware is to execute the first instruction, execution of the first instruction to include determining a first virtual processor-priority value and storing the first virtual processor-priority value in a virtual copy of a processor-priority field, where the virtual copy of the processor-priority field is a virtual resource corresponding to a physical resource associated with an interrupt controller.

Abstract: Embodiments of apparatuses, methods, and systems for delivering an interrupt to a virtual processor are disclosed. In one embodiment, an apparatus includes an interface to receive an interrupt request, delivery logic, and exit logic. The delivery logic is to determine, based on an attribute of the interrupt request, whether the interrupt request is to be delivered to the virtual processor. The exit logic is to transfer control to a host if the delivery logic determines that the interrupt request is not to be delivered to the virtual processor.

Abstract: Methods and systems for advanced interrupt processing and scheduling are provided. The system comprises a memory operable to store interrupt priorities, an interface, and a processor operable to acquire incoming interrupts and to handle the incoming interrupts according to the interrupt priorities. The processor is also operable to receive interrupt processing criteria from the interface (sent, for example, from a device not directly coupled with the system), and to modify the interrupt priorities of the memory based upon the interrupt processing criteria without losing incoming processing requests for the system. Additionally, the processor is operable to process the incoming interrupts according to the modified interrupt priorities responsive to modifying the interrupt priorities.

Abstract: A sample is generated based on an event. Further, an interrupt handler captures information for an interrupted thread on a current processor. In addition, an affinity of the interrupted thread is set such that the interrupted thread runs only on the current processor without being able to migrate to a different processor. A sampler thread that runs on the current processor retrieves a call stack associated with the interrupted thread after the affinity of the interrupted thread has been set to the current processor. The affinity of the interrupted thread is restored after the call stack has been retrieved.

Abstract: Methods and apparatuses are provided for servicing an interrupt in a computer system. The method includes a device driver receiving an interrupt request. The device driver is responsive to the interrupt request to store interrupt data in a portion of the memory. The interrupt data includes identification of at least one processor of the plurality of processors capable of servicing the interrupt request; priority of the interrupt request; a thread context; and an address for instructions to service the interrupt request. The device driver then instructs the peripheral device to issue a memory write to the plurality of processors so that each may determine if it can use the thread context and the instructions to service the interrupt. A computer system is provided with the hardware needed to perform the method.

Abstract: Methods and apparatus for interleaving priorities of a plurality of virtual processors are disclosed. A hypervisor assigns a base priority to each virtual processor and schedules one or more virtual processors to execute on one or more physical processors based on the current priority associated with each virtual processor. When the hypervisor receives an indication from one of the virtual processors that its current priority may be temporarily reduced, the hypervisor lowers the current priority of that virtual processor. The hypervisor then schedules another virtual processor to execute on a physical processor instead of the virtual processor with the temporarily reduced priority. When the hypervisor receives an interrupt for the virtual processor with the lowered priority, the hypervisor raises the priority of that virtual processor and schedules the virtual processor with the restored priority to execute on a physical processor so that processor can handle the interrupt.

Abstract: A global interrupt number space 38 is provided for use in message signalled interrupts. Interrupt destinations 10, 12, 14, 16 are provided with pending interrupt caches 24 with either backing storage provided by global pending status memory 34 shared by all the caches or separate individual pending status memories 56. The interrupt number space may be divided into regions with programmable mapping data being used to indicate which interrupt destinations are responsible for which regions. When interrupts are migrated from one interrupt destination to another, then such programmable mapping data is updated. Pending interrupts may be flushed back to the global pending status memory 34 during the reassignment process such that this pending interrupt data may be picked up by the newly responsible interrupt destination.

Abstract: Methods and systems for advanced interrupt processing and scheduling are provided. The system comprises a memory operable to store interrupt priorities, an interface, and a processor operable to acquire incoming interrupts and to handle the incoming interrupts according to the interrupt priorities. The processor is also operable to receive interrupt processing criteria from the interface (sent, for example, from a device not directly coupled with the system), and to modify the interrupt priorities of the memory based upon the interrupt processing criteria without losing incoming processing requests for the system. Additionally, the processor is operable to process the incoming interrupts according to the modified interrupt priorities responsive to modifying the interrupt priorities.

Abstract: Methods and systems for advanced interrupt processing and scheduling are provided. The system comprises a memory operable to store interrupt priorities, an interface, and a processor operable to acquire incoming interrupts and to handle the incoming interrupts according to the interrupt priorities. The processor is also operable to receive interrupt processing criteria from the interface (sent, for example, from a device not directly coupled with the system), and to modify the interrupt priorities of the memory based upon the interrupt processing criteria without losing incoming processing requests for the system. Additionally, the processor is operable to process the incoming interrupts according to the modified interrupt priorities responsive to modifying the interrupt priorities.

Abstract: The present disclosure relates to a method for executing, by a processor, a program read in a program memory, comprising steps of: detecting a program memory read address jump; providing prior to a jump address instruction for jumping a program memory read address, an instruction for storing the presence of the jump address instruction; and activating an error signal if an address jump has been detected and if the presence of a jump address instruction has not been stored. The present disclosure also relates to securing integrated circuits.

Abstract: An audio-video (AV) playback chain and rendering peripheral device 300 for generating two or more interrupts 306, 308 with a programmable delay 304 between them. Such are configured to prevent two processors 310, 314 from racing to access the same system resources in their respective interrupt service routines.

Abstract: Embodiments of processors, methods, and systems for virtualizing interrupt prioritization and delivery are disclosed. In one embodiment, a processor includes instruction hardware and execution hardware. The instruction hardware is to receive a plurality of instructions, including a first instruction to transfer the processor from a root mode to a non-root mode for executing guest software in a virtual machine, wherein the processor is to return to the root mode upon the detection of any of a plurality of virtual machine exit events. The execution hardware is to execute the first instruction, execution of the first instruction to include determining a first virtual processor-priority value and storing the first virtual processor-priority value in a virtual copy of a processor-priority field, where the virtual copy of the processor-priority field is a virtual resource corresponding to a physical resource associated with an interrupt controller.

Abstract: An interrupt control apparatus and interrupt control method reduce situations in which the output of interrupt information is suspended and thus reduce stress caused in a user, without missing the appropriate output timing for interrupt information having a high priority level. A priority level setting unit raises the value of a priority level for an interrupt voice message during a period in which the interrupt voice message is being outputted, and a voice output control unit, when interrupts from two or more overlapping interrupt voice messages occurs, carries out control in accordance with priority levels set for each of the two or more interrupt voice messages so that the interrupt voice message having the higher priority level value is preferentially outputted.

Abstract: Methods and systems for advanced interrupt processing and scheduling are provided. The system comprises a memory operable to store interrupt priorities, an interface, and a processor operable to acquire incoming interrupts and to handle the incoming interrupts according to the interrupt priorities. The processor is also operable to receive interrupt processing criteria from the interface (sent, for example, from a device not directly coupled with the system), and to modify the interrupt priorities of the memory based upon the interrupt processing criteria without losing incoming processing requests for the system. Additionally, the processor is operable to process the incoming interrupts according to the modified interrupt priorities responsive to modifying the interrupt priorities.

Abstract: Technologies are generally described herein for handling interrupts within a multiprocessor computing system. A priority level associated with a current task for each processor of the multiprocessor computing system can be maintained. Cache state information associated with each processor can also be maintained. Upon receiving an interrupt to the multiprocessor computing system, a cache locality score for each processor can be determined based on the maintained cache state information. A value can be computed that balances, for each processor, the priority level and the cache locality score. A processor for servicing the interrupt can be determined based on the computed value. The determined processor can be signaled to service the interrupt. Tracking state information related to processor cores can support rapid allocation of an arriving interrupt to a processor core without collecting processor core state information at interrupt time.

Abstract: Various technologies and techniques are disclosed that provide fast context switching. One embodiment provides a method for a context switch comprising preloading a host virtual machine context in a first portion of a processor, operating a guest virtual machine in a second portion of the processor, writing parameters of the host virtual machine context to a memory location shared by the host virtual machine and the guest virtual machine, and operating the host virtual machine in the processor. In this manner, a fast context switch may be accomplished by preloading the new context in a virtual processor, thus reducing the delay to switch to the new context.

Abstract: Efficient techniques are described for identifying active interrupt requests to improve performance and reduce power requirements in a processor system. A method to identify active sampled interrupt requests begins with scanning groups of the sampled interrupt requests one group at a time to identify an active interrupt request in any scanned group. A group of interrupt requests is an M/R priority of N sampled interrupt requests, M is the number of priority levels, and R is a resource sharing factor. A group selection circuit is updated to a new group in response to having identified an active interrupt request to improve the latency in processing high priority interrupt requests. Also, groups having active interrupt requests may be identified by early detection or look ahead circuitry. The scanning of groups of interrupt requests may be stopped until the next interrupt request sample point has been reached to reduce power utilization.

Abstract: A method and system for controlling transmission and execution of commands in an integrated circuit (IC) device provide transmission of commands and acknowledgements in an order of their priorities. Priority levels of the commands and acknowledgements are defined based on pre-assigned levels of precedence of the respective master and slave devices. In one application, the invention is used to increase performance of IC devices employing an Advanced eXtensible Interface (AXI).

Abstract: A system and a method for reducing interrupt latency is described. The system includes a first interrupt source configured to generate a first interrupt, a second interrupt source configured to generate a second interrupt, and a processor. The processor includes a shadow set that stores data used to service the first interrupt. The processor receives the second interrupt and receives a designation of the shadow set to service the second interrupt. The processor determines, based on a dedicated bit, whether the shadow set is used to service the first interrupt upon receiving the second interrupt.

Abstract: A microcomputer system includes a CPU, a memory, and a runaway detector. The CPU includes a controller for outputting a task information signal. The task information signal is activated, if the CPU performs the most important task at the present time. A program for the most important task is stored in the memory. The runaway detector includes an address register and a program area checker. The address register stores start and end addresses of the program area. The program area checker determines whether an execution address of the CPU is within the program area by comparing the execution address with each of the start and end addresses. The runaway detector detects a task runaway in the event of conflict between the task information signal and a result of a determination of the program area checker.

Abstract: A computer system which shortens standby time of CPUs and improves CPU processing efficiency of a performance mode upon switching from the performance mode (parallel operation) to a safety mode (master/checker operation) is provided. In a computer system including: at least two CPUs; a programmable interrupt controller for interrupting the CPUs; and a comparator for mutually comparing outputs of the CPUs, switching between the performance mode of executing mutually different processes by the CPUs, respectively, to improve performance and the safety mode of executing mutually the same processes by the CPUs and collating results by the comparator to detect failure can be carried out; CPUs to be interrupted can be set for each interrupt factor; and whether the performance mode is to be executed or the safety mode is to be executed can be set for each interrupt factor.

Abstract: In some embodiments, an apparatus includes processors, signal storage circuitry, and processor selection logic. The signal storage circuitry is to hold willingness indication signals each indicative of a willingness level of an associated one of the processors to receive an interrupt and to hold priority indication signals each indicative of a processor priority level of an associated one of the processors, wherein there are multiple possible willingness levels and multiple possible processor priority levels. The processor selection logic is to select one of the processors to receive an interrupt based at least on the willingness indication signals. Other embodiments are described.

Abstract: Technologies are generally described herein for handling interrupts within a multiprocessor computing system. Upon receiving an interrupt at the multiprocessor computing system, a priority level associated with an interrupt handler for the interrupt can be determined. Current task priority levels can be queried from one or more processors of the multiprocessor computing system. One of the processors can be assigned to execute the interrupt handler in response to the processor having a lowest current task priority level. Interrupt arbitration can schedule and communicate interrupt responses among processor cores in a multiprocessor computing system. Arbitration can query information about current task or thread priorities from a set of processor cores upon receiving an interrupt. The processor core that is currently idle or running the lowest priority task may be selected to service the interrupt.

Abstract: An embedded system and an interruption handling method are provided. A plurality of interruption requests are received, and corresponding service routines are triggered with priority control. In the embedded system, a memory device comprises a plurality of service routines stored at different entry addresses, each related to an interruption request. A processor receives an enable signal to initialize one of the service routines through a branch instruction. A control unit buffers the interruption requests to schedule executions of corresponding service routines. When a specific service routine is to be executed, the control unit provides the branch instruction pointing to entry address of the specific service routine and asserts the enable signal to the processor, such that the processor executes the branch instruction to initialize the specific service routine.

Abstract: The present invention provides a technique capable of processing a plurality of interrupt causes sharing one interrupt request in different processors. An interrupt controller outputs an interrupt request when the interrupt request shared by a plurality of interrupt causes is notified. The interrupt request output by the interrupt controller is accepted by one of the processors. The processor accepting the interrupt request determines whether the interrupt cause that the processor must process has occurred, executes an interrupt processing when such interrupt cause has occurred, and notifies the generation of the interrupt request to another processor that processes another interrupt cause of the plurality of interrupt causes sharing the interrupt request when the relevant interrupt cause has not occurred.

Abstract: A method for configuration of a program with a plurality of configuration variables to operate on a computer system that includes obtaining a plurality of priority semantics for the plurality of configuration variables, wherein the plurality of priority semantics are heterogeneous, assigning a value for each of the plurality of configuration variables based on the plurality of priority semantics, and configuring the program using the value to operate on the computer system.

Abstract: Technologies are generally described herein for handling interrupts within a multiprocessor computing system. Upon receiving an interrupt at the multiprocessor computing system, a priority level associated with an interrupt handler for the interrupt can be determined. Current task priority levels can be queried from one or more processors of the multiprocessor computing system. One of the processors can be assigned to execute the interrupt handler in response to the processor having a lowest current task priority level. Interrupt arbitration can schedule and communicate interrupt responses among processor cores in a multiprocessor computing system. Arbitration can query information about current task or thread priorities from a set of processor cores upon receiving an interrupt. The processor core that is currently idle or running the lowest priority task may be selected to service the interrupt.

Abstract: The invention relates to a device to be used with a scheduling method, and to a scheduling method, in particular a context scheduling method, comprising the steps of performing a scheduling for threads to be executed by a multithreaded processor, wherein the scheduling is performed as a function of index variables assigned to the threads. That thread whose index variable has the highest, or—in an alternative—the lowest value may be selected as the respective thread to be executed by the processor.

Abstract: System and methods for preventing an operating-system scheduler in a computer system from crashing as a result of an uncleared periodic interrupt are disclosed. A periodic interrupt is generated using a real-time clock (RTC) residing on a chipset. A flag indicating a periodic interrupt is entered into a status register associated with the RTC in firmware residing on the CMOS chip, if the status register indicates no periodic interrupt has been pending. An interrupt handler associated with the RTC attempts to handle the periodic interrupt, if pending. If the periodic interrupt is pending after a preset interval of time elapses, a basic-input-output system (BIOS) residing on a memory unit coupled to the chipset generates a system-management interrupt (SMI). If the periodic interrupt is pending after the preset interval of time elapses, a firmware SMI handler residing on the memory unit clears the pending periodic interrupts from the status register.

Abstract: A data processing apparatus comprises a processing unit which is responsive to a plurality of interrupt signals to carry out a corresponding interrupt routine. On receipt of an interrupt signal, the processing unit stores data values from a plurality of registers onto a data stack and carries out the corresponding interrupt routine. Thereafter the processor returns the data values from the data stack to the registers and carries on the processing it was performing when the interrupt was received. If a higher priority interrupt is received whilst the processor is transferring register values to or from the data stack, that transferral is abandoned and the processing unit immediately begins transferring data values from the registers to the data stack in response to the higher priority interrupt.

Abstract: Interrupts are directed to currently idle processors. Which of a number of processors of a computing system that are currently idle is determined. An interrupt is received and directed to one of the currently idle processors for processing. Determining which processors are currently idle can be accomplished by monitoring each processor to determine whether it has entered an idle state. When a processor has entered an idle state, it is thus determined that the processor is currently idle. Where just one processor is currently idle, an interrupt is directed to this processor. Where more than one processor is currently idle, one of these processors is selected to which to deliver an interrupt, such as in a round-robin manner. Where no processor is currently idle, then one of the processors is selected to which to deliver an interrupt.

Abstract: An Interrupt Processor is provided in an embedded system to handle interrupts generated in the system. The function of the interrupt processor is to handle interrupts and execute interrupt routines. It performs code execution for interrupts which require immediate response. The other interrupts received by the interrupt processor are arranged in a queue on the basis of their respective priorities. An interrupt signal is then sent to the main processor which processes all the signals in one go. This prevents multiple and frequent switching of the main processor and hence avoids the switching overhead. Since the main processor operates at low frequency, the system consumes less power as compared to conventional systems.

Abstract: A method and apparatus for generating an interrupt vector associated with either core (internal) generated or off-core (external) generated interrupts is provided. The apparatus includes a number of programmable interrupt priority level fields for storing priority levels for the core generated interrupts, and for the externally generated interrupts, if desired. The apparatus further includes a programmable offset register for storing an offset to be used in calculating the interrupt vector. The apparatus further includes a priority encoder that sorts all of the received interrupts, whether on-core or off-core, according to their priority, utilizing the programmed interrupt priority levels. The priority encoder provides an indication of the received interrupt with the highest priority to a vector generator. The vector generator receives the indication, and calculates an interrupt vector utilizing the programmed offset.

Abstract: A data processing apparatus comprises a processing unit which is responsive to a plurality of interrupt signals to carry out a corresponding interrupt routine. On receipt of an interrupt signal, the processing unit stores data values from a plurality of registers onto a data stack and carries out the corresponding interrupt routine. Thereafter the processor returns the data values from the data stack to the registers and carries on the processing it was performing when the interrupt was received. If a higher priority interrupt is received whilst the processor is transferring register values to or from the data stack, that transferral is abandoned and the processing unit immediately begins transferring data values from the registers to the data stack in response to the higher priority interrupt.

Abstract: An interrupt controller superior in maintenance performance and expandability. An interrupt controller 10 comprises a queue circuit 11 that holds channel numbers corresponding to interrupt inputs in the order of priority levels, and a queue control circuit 12 that changes the order of the channels held in the queue circuit 11 according to a new order of the priority levels when a priority level that corresponds to any channel number is changed. The order of the channel numbers in the queue circuit 11 is changed at a time of setting the priority levels unrelated to interrupt inputs. In order to select an interrupt to be notified to a CPU 20, an interrupt factor selection circuit 15 checks whether or not each channel number held in the queue circuit 11 has an interrupt input in turn from the head of the queue.

Abstract: An interrupt controller 2 is provided with priority registers 6 storing priority values P0-P9 used to determine prioritisation between received interrupt signals I0-I9. A priority value accessing circuit 10 provides multiple mappings to the priority values stored in dependence upon the priority value manager 16, 18, seeking to make an access. In this way, a first priority value manager 18, such as a secure operating system, can be given exclusive access to the highest priority values whilst a second priority value manager 16, such as a non-secure operating system, can be given access to a range of priority values as stored which are of a lower priority and yet as written or read by the non-secure operating system appear to the non-secure operating system to have a different, such as higher, priority level.

Abstract: A storage controller receives an interrupt control directive from a host. The storage controller generates a first plurality of interrupts, in response to access requests received from the host for at least one storage device coupled to the storage controller, wherein the first plurality of interrupts indicates whether access to the at least one storage device is allowed to the host. The storage controller generates a second plurality of interrupts, wherein the second plurality of interrupts comprises unsolicited interrupts for the host that are different from the first plurality of interrupts. The storage controller controls how many of the first plurality of interrupts and how many of the second plurality interrupts to send to the host, based on the received interrupt control directive.

Abstract: A storage controller receives an interrupt control directive from a host. The storage controller generates a first plurality of interrupts, in response to access requests received from the host for at least one storage device coupled to the storage controller, wherein the first plurality of interrupts indicates whether access to the at least one storage device is allowed to the host. The storage controller generates a second plurality of interrupts, wherein the second plurality of interrupts comprises unsolicited interrupts for the host that are different from the first plurality of interrupts. The storage controller controls how many of the first plurality of interrupts and how many of the second plurality interrupts to send to the host, based on the received interrupt control directive.

Abstract: Methods and apparatus are provided for implementing a bus arbitration priority encoding scheme with fairness. Bus arbitration logic is connected to multiple primary components or devices. The multiple primary components send requests to bus arbitration logic. The bus arbitration logic uses a request vector and an arbitration vector to determine a grant vector. The grant vector indicates what primary component should be allowed bus access.

Abstract: An interrupt controller has an interrupt register unit receiving a plurality of interrupt source signals, an interrupt detector coupled to the interrupt register unit, a counter unit coupled to the interrupt detector, wherein on the first occurrence of an interrupt source signal the counter unit defines a time window during which the interrupt register stores further interrupt source signals, and an interrupt request unit coupled to the counter unit for generating an interrupt request signal.

Abstract: A mobile communication apparatus configured to communicate with an opposite communication device is provided. The mobile communication apparatus includes a transceiver configured to receive an incoming signal sent from the opposite communication device. The transceiver is configured to produce an interrupt signal upon receiving the incoming signal. The mobile communication apparatus includes a first memory device and a non-volatile second memory device. The mobile communication apparatus includes a controller connected to the transceiver, the first memory device and the second memory device. The controller is configured to perform garbage collection of the second memory device, to load data stored in one of the first memory device and the second memory device into another of the first memory device and the second memory device, to access the first memory device if the transceiver produces the interrupt signal.

Abstract: An idle mode system has a clock gating circuit, a bus interface unit, memory interfaces and an interrupt and idle control unit. The clock gating circuit receives a first clock and designated idle-acknowledge signals. The clock gating circuit produces a second clock signal based on the first clock signal when fewer than all designated idle-acknowledge signals are received. The clock gating circuit produces no second clock signal when all designated idle-acknowledge signals are received. The bus interface unit receives bus access requests and receives the first and second clock signals. When a bus access request is made, the bus interface unit de-asserts its idle-acknowledge signal and passes the bus access request. The memory interfaces operate on the second clock. One interface receives the bus access request from the bus interface unit, withdraws its idle-acknowledge signal, processes the bus access request, and re-asserts its idle-acknowledge signal upon completion.

Abstract: A data processing system 2 having a nested interrupt controller 24 supports nested active interrupts. The priority levels associated with different interrupts are alterable (possibly programmable) whilst the system is running. In order to prevent problems associated with priority inversions within nested interrupts, the nested interrupt controller when considering whether a pending interrupt should pre-empt existing active interrupts, compares the priority of the pending interrupt with the highest priority of any of the currently active interrupts that are nested together.

Abstract: A computer-implemented method for handling pending interrupt vectors of a pending interrupt list is disclosed. The method includes batch-reading the set of pending interrupt vectors into a working list of working interrupt vectors. The method also includes performing interrupt handling of the working interrupt vectors using an interrupt handling arrangement until the working list is empty. The interrupt handling process permits a first incoming interrupt vector that is received by the pending interrupt list after the batch reading to temporarily interrupt the performing interrupt handling of the working interrupt vectors and to be handled on a priority basis by the interrupt handling arrangement if a priority level of the first incoming interrupt vector is higher than a priority level of a first working interrupt vector being currently handled by the interrupt handling arrangement.