Abstract: The present disclosure advantageously provides a system cache and a method for storing coherent data and non-coherent data in a system cache. A transaction is received from a source in a system, the transaction including at least a memory address, the source having a location in a coherent domain or a non-coherent domain of the system, the coherent domain including shareable data and the non-coherent domain including non-shareable data. Whether the memory address is stored in a cache line is determined, and, when the memory address is not determined to be stored in a cache line, a cache line is allocated to the transaction including setting a state bit of the allocated cache line based on the source location to indicate whether shareable or non-shareable data is stored in the allocated cache line, and the transaction is processed.

Abstract: An apparatus and method are provided for handling protocol conversion. The apparatus has interconnect circuitry for routing messages between components coupled to the interconnect circuitry in a manner that conforms to a first communication protocol. Protocol conversion circuitry is coupled between the interconnect circuitry and an external communication path, for converting messages between the first communication protocol and a second communication protocol that has a layered architecture comprising multiple layers. The protocol conversion circuitry has a gateway component forming one of the components coupled to the interconnect circuitry, and a controller coupled with the gateway component and used to control connection with the external communication path.

Abstract: The present disclosure advantageously provides a system cache and a method for storing coherent data and non-coherent data in a system cache. A transaction is received from a source in a system, the transaction including at least a memory address, the source having a location in a coherent domain or a non-coherent domain of the system, the coherent domain including shareable data and the non-coherent domain including non-shareable data. Whether the memory address is stored in a cache line is determined, and, when the memory address is not determined to be stored in a cache line, a cache line is allocated to the transaction including setting a state bit of the allocated cache line based on the source location to indicate whether shareable or non-shareable data is stored in the allocated cache line, and the transaction is processed.

Abstract: An apparatus and method are provided for handling protocol conversion. The apparatus has interconnect circuitry for routing messages between components coupled to the interconnect circuitry in a manner that conforms to a first communication protocol. Protocol conversion circuitry is coupled between the interconnect circuitry and an external communication path, for converting messages between the first communication protocol and a second communication protocol that has a layered architecture comprising multiple layers. The protocol conversion circuitry has a gateway component forming one of the components coupled to the interconnect circuitry, and a controller coupled with the gateway component and used to control connection with the external communication path.

Abstract: Interconnect circuitry and a method of operating the interconnect circuitry are provided, where the interconnect circuitry is suitable to couple at least two master devices to a memory, each comprising a local cache. Any access to the memory mediated by the interconnect circuitry is policed by a memory protection controller situated between the interconnect circuitry and the memory. The interconnect circuitry modifies a coherency type associated with a memory transaction received from one of the master devices to a type which ensures that when a modified version of a copy of a transaction target specified by the issuing master device is stored in a local cache of another master device an access to the transaction target in the memory must take place and therefore must be policed by the memory protection controller.

Abstract: A memory interface apparatus 24 is provided with first interface circuitry 28, second interface circuitry 30 and transaction control circuitry 32. The first interface circuitry receives a first write request from a transaction master 20, 22 and issues a further transaction request associated with the memory address of the first write request via the second interface circuitry to a memory system. When an indication of the completion of the further transaction has been received at the second interface circuitry, then a second write request may be issued from the second interface circuitry to the memory system to write the target data associated with the first write request. After a write response signal in respect of the second write request is received at the second interface circuitry, then an acknowledge signal RACK indicating completion of the further transaction and that the write response signal has been received may be issued from the second interface circuitry.

Abstract: Interconnect circuitry and a method of operating the interconnect circuitry are provided, where the interconnect circuitry is suitable to couple at least two master devices to a memory, each comprising a local cache. Any access to the memory mediated by the interconnect circuitry is policed by a memory protection controller situated between the interconnect circuitry and the memory. The interconnect circuitry modifies a coherency type associated with a memory transaction received from one of the master devices to a type which ensures that when a modified version of a copy of a transaction target specified by the issuing master device is stored in a local cache of another master device an access to the transaction target in the memory must take place and therefore must be policed by the memory protection controller.

Abstract: Interconnect circuitry configured to provide routes for interconnecting several initiator devices and at least one recipient device including a memory. At least one of the initiator devices has a cache for storing a local copy of a subset of data items stored in the memory. The interconnect circuitry includes: a plurality of input ports and at least one output port; a plurality of paths for transmitting the transaction requests between the inputs and the at least one output; coherency control circuitry for maintaining an order in which at least some of the transaction requests to a same data storage location proceed through the interconnect circuitry. The interconnect circuitry is configured not to control the writeback transaction requests with the coherency control circuitry, such that the writeback transaction requests proceed independently of transaction requests routed through the coherency control circuitry.

Abstract: An apparatus and method are provided for performing verification tests for a design of a data processing system. The apparatus comprises a system under verification representing at least part of the design of the data processing system, and a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via the interface during performance of the verification tests. Profile storage stores a profile providing a statistical representation of desired traffic flow at the interface, the statistical representation providing statistical information for a plurality of traffic attributes and also identifying at least one dependency between such traffic attributes. The transactor then references the profile in order to determine the signals to be generated, such that the signals generated take account of the specified dependencies identified in the profile.

Abstract: A data processing apparatus for forming a portion of a coherent cache system comprises at least one master device for performing data processing operations, and a cache coupled to the at least one master device and arranged to store data values for access by that at least one master device when performing the data processing operations. Cache coherency circuitry is responsive to a coherency request from another portion of the coherent cache system to cause a coherency action to be taken in respect of at least one data value stored in the cache. Responsive to an indication that the coherency action has resulted in invalidation of that at least one data value in the cache, refetch control circuitry is used to initiate a refetch of that at least one data value into the cache.

Abstract: A memory interface apparatus 24 is provided with first interface circuitry 28, second interface circuitry 30 and transaction control circuitry 32. The first interface circuitry receives a first write request from a transaction master 20, 22 and issues a further transaction request associated with the memory address of the first write request via the second interface circuitry to a memory system. When an indication of the completion of the further transaction has been received at the second interface circuitry, then a second write request may be issued from the second interface circuitry to the memory system to write the target data associated with the first write request. After a write response signal in respect of the second write request is received at the second interface circuitry, then an acknowledge signal RACK indicating completion of the further transaction and that the write response signal has been received may be issued from the second interface circuitry.

Abstract: Interconnect logic is provided for coupling master logic units and slave logic units within a data processing apparatus to enable transactions to be performed. Each transaction comprises an address transfer from a master logic unit to a slave logic unit and one or more data transfers between that master logic unit and that slave logic unit. The interconnect logic comprises a plurality of connection paths for providing at least one address channel for carrying address transfers and at least one data channel for carrying data transfers, and control logic is used to control the use of the at least one address channel and the at least one data channel in order to enable the transactions to be performed.

Abstract: Interconnect circuitry configured to provide routes for interconnecting several initiator devices and at least one recipient device including a memory. At least one of the initiator devices has a cache for storing a local copy of a subset of data items stored in the memory. The interconnect circuitry includes: a plurality of input ports and at least one output port; a plurality of paths for transmitting the transaction requests between the inputs and the at least one output; coherency control circuitry for maintaining an order in which at least some of the transaction requests to a same data storage location proceed through the interconnect circuitry. The interconnect circuitry is configured not to control the writeback transaction requests with the coherency control circuitry, such that the writeback transaction requests proceed independently of transaction requests routed through the coherency control circuitry.

Abstract: An on-chip integrated circuit interconnect 16 uses a serialization technique to divide a transaction to be transmitted into a sequence of transmission packets which are serially transmitted over a narrower connection. The order in which bits of the transaction are allocated to transmission packets is selected such that higher priority bits required by a receiving slave device in order that it can commence processing the transaction are sent first. This reduces the latency of the system.

Abstract: A data processing apparatus for forming a portion of a coherent cache system comprises at least one master device for performing data processing operations, and a cache coupled to the at least one master device and arranged to store data values for access by that at least one master device when performing the data processing operations. Cache coherency circuitry is responsive to a coherency request from another portion of the coherent cache system to cause a coherency action to be taken in respect of at least one data value stored in the cache. Responsive to an indication that the coherency action has resulted in invalidation of that at least one data value in the cache, refetch control circuitry is used to initiate a refetch of that at least one data value into the cache.

Abstract: An apparatus and method are provided for performing verification tests for a design of a data processing system. The apparatus comprises a system under verification representing at least part of the design of the data processing system, and a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via the interface during performance of the verification tests. Profile storage stores a profile providing a statistical representation of desired traffic flow at the interface, the statistical representation providing statistical information for a plurality of traffic attributes and also identifying at least one dependency between such traffic attributes. The transactor then references the profile in order to determine the signals to be generated, such that the signals generated take account of the specified dependencies identified in the profile.

Abstract: The present invention provides a data processing apparatus and method for managing snoop operations. The data processing apparatus has a plurality of processing units for performing data processing operations requiring access to data in shared memory, with at least two of the processing units having a cache associated therewith for storing a subset of the data for access by that processing unit. A snoop-based cache coherency protocol is employed to ensure data accessed by each processing unit is up-to-date, and when an access request is issued the cache coherency protocol is referenced in order to determine whether a snoop process is required. Snoop control storage is provided which defines a plurality of snoop schemes, each snoop scheme defining a series of snoop phases to be performed to implement the snoop process, and each snoop phase requiring a snoop operation to be performed on either a single cache or multiple caches.

Abstract: An integrated circuit 2 includes a transaction master 4 connected via interconnect circuitry 10 to a transaction slave 12. The transaction slave 12 generates a transfer-complete signal (R Last or B) to indicate completion of a data transfer (either a read or a write). When this transfer-complete signal has been received by the transaction master 4, then the transaction master 4 generates a complete-acknowledgement signal RACK, WACK, which is passed back to the transaction slave so as to acknowledge receipt of the transfer-complete signal.

Abstract: The present invention provides a data processing apparatus and method for managing snoop operations. The data processing apparatus has a plurality of processing units for performing data processing operations requiring access to data in shared memory, with at least two of the processing units having a cache associated therewith for storing a subset of the data for access by that processing unit. A snoop-based cache coherency protocol is employed to ensure data accessed by each processing unit is up-to-date, and when an access request is issued the cache coherency protocol is referenced in order to determine whether a snoop process is required. Snoop control storage is provided which defines a plurality of snoop schemes, each snoop scheme defining a series of snoop phases to be performed to implement the snoop process, and each snoop phase requiring a snoop operation to be performed on either a single cache or multiple caches.

Abstract: An on-chip integrated circuit interconnect 16 uses a serialization technique to divide a transaction to be transmitted into a sequence of transmission packets which are serially transmitted over a narrower connection. The order in which bits of the transaction are allocated to transmission packets is selected such that higher priority bits required by a receiving slave device in order that it can commence processing the transaction are sent first. This reduces the latency of the system.