Abstract: In one embodiment, a direct memory access (DMA) controller comprises a transmit control circuit, an offload engine, and a receive control circuit. The transmit control circuit is configured to read first DMA data from an address space in a host. Coupled to receive the first DMA data from the transmit control circuit, the offload engine is configured to perform at least a first operation on the first DMA data to produce a result. The offload engine is configured to at least start performing the first operation during a DMA transfer that provides the first DMA data to the offload engine. Coupled to the offload engine to receive the result, the receive control circuit is configured to write the result to the address space in the host according to a DMA descriptor data structure that describes the DMA transfer.

Abstract: In one embodiment, a direct memory access (DMA) controller comprises a transmit control circuit, an offload engine, and a receive control circuit. The transmit control circuit is configured to read first DMA data from an address space in a host. Coupled to receive the first DMA data from the transmit control circuit, the offload engine is configured to perform at least a first operation on the first DMA data to produce a result. The offload engine is configured to at least start performing the first operation during a DMA transfer that provides the first DMA data to the offload engine. Coupled to the offload engine to receive the result, the receive control circuit is configured to write the result to the address space in the host according to a DMA descriptor data structure that describes the DMA transfer.

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: A system on a chip for network devices. In one implementation, the system on a chip may include (integrated onto a single integrated circuit), a processor and one or more I/O devices for networking applications. For example, the I/O devices may include one or more network interface circuits for coupling to a network interface. In one embodiment, coherency may be enforced within the boundaries of the system on a chip but not enforced outside of the boundaries.

Abstract: In one embodiment, a direct memory access (DMA) controller comprises a transmit circuit and a data flow control circuit coupled to the transmit circuit. The transmit circuit is configured to perform DMA transfers, each DMA transfer described by a DMA descriptor stored in a data structure in memory. There is a data structure for each DMA channel that is in use. The data flow control circuit is configured to control the transmit circuit's processing of DMA descriptors for each DMA channel responsive to data flow control data in the DMA descriptors in the corresponding data structure.

Abstract: A system on a chip for network devices. In one implementation, the system on a chip may include (integrated onto a single integrated circuit), a processor and one or more I/O devices for networking applications. For example, the I/O devices may include one or more network interface circuits for coupling to a network interface. In one embodiment, coherency may be enforced within the boundaries of the system on a chip but not enforced outside of the boundaries.

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 system comprises at least a first node and a second node coupled to a network. The second node comprises a local memory and a direct memory access (DMA) controller coupled to the local memory. The first node is configured to transmit at least a first packet to the second node to access data in the local memory and at least one other packet that is not coded to access the local memory. The second node is configured to capture the packet from a data link layer of a protocol stack, and wherein the DMA controller is configured to perform one more transfers with the local memory to access the data specified by the first packet responsive to the first packet received from the data link layer. The second node is configured to process the other packet to a top of the protocol stack.

Abstract: A packet processing system may include a processor, a cache, a memory controller, and at least one packet interface circuit integrated into a single integrated circuit. In one embodiment (which may be used in integrated or non-integrated systems), the packet interface circuit is configured to cause allocation in the cache of a portion of a received packet. In one embodiment (which may be used in integrated or non-integrated systems), the memory controller may be configured to selectively block memory transactions. Particularly, the memory controller may implement at least two block signals, one for the packet interface circuit and one for other devices. The block signals may be used to control the initiation of memory transactions when the memory controller's input queue is approaching fullness.

Abstract: A packet processing system may include a processor, a cache, a memory controller, and at least one packet interface circuit integrated into a single integrated circuit. In one embodiment (which may be used in integrated or non-integrated systems), the packet interface circuit is configured to cause allocation in the cache of a portion of a received packet. In one embodiment (which may be used in integrated or non-integrated systems), the memory controller may be configured to selectively block memory transactions. Particularly, the memory controller may implement at least two block signals, one for the packet interface circuit and one for other devices. The block signals may be used to control the initiation of memory transactions when the memory controller's input queue is approaching fullness.

Abstract: A system may include at least a first agent and a second agent, and the first agent may be coupled to receive a block signal generated by the second agent. The block signal is indicative of whether or not the second agent is capable of participating in transactions. The first agent initiates or inhibits initiation of a transaction for which the second agent is a participant responsive to the block signal. The system may include additional agents, each configured to generate independent block signals. Other implementations may share block signals among two or more agents. For example, a memory block signal indicative of memory transactions being blocked or not blocked and an input/output (I/O) block signal indicative of I/O transactions being blocked or not blocked may be employed. In yet another implementation, a first agent may provide separate block signals to other agents.

Abstract: An apparatus includes a storage location and a write monitor circuit coupled to the storage location. The storage location is configured to store a write response indicator which is capable of indicating a reception of at least one write response. Each write response indicates that a corresponding write has reached a target device of that write. The write monitor circuit is configured to update the write response indicator in response to receiving an indication of a first write response. A computer accessible medium may comprises instructions which, when executed: (i) initialize the write response indicator; and (ii) issue one or more writes to a target device, wherein the target device is configured to response to each of the writes with a write response to be indicated by the write response indicator.

Abstract: A memory controller provides programmable flexibility, via one or more configuration registers, for the configuration of the memory. The memory may be optimized for a given application by programming the configuration registers. For example, in one embodiment, the portion of the address of a memory transaction used to select a storage location for access in response to the memory transaction may be programmable. In an implementation designed for DRAM, a first portion may be programmably selected to form the row address and a second portion may be programmable selected to form the column address. Additional embodiments may further include programmable selection of the portion of the address used to select a bank. Still further, interleave modes among memory sections assigned to different chip selects and among two or more channels to memory may be programmable, in some implementations.

Abstract: An adaptive retry mechanism may record latencies of recent transactions (e.g. the first data transfer latency), and may select a retry latency from two or more retry latencies. The retry latency may be used for a transaction, and may specify a point in time during the transaction at which the transaction is retried if the first data transfer has not yet occurred. In one implementation, the set of retry latencies includes a minimum retry latency, a nominal retry latency, and a maximum retry latency. The nominal retry latency may be set slightly greater than the expected latency of transactions in the system. The minimum retry latency may be less than the nominal retry latency and the maximum retry latency may be greater than the nominal retry latency. If latencies greater than the nominal retry latency but less than the maximum retry latency are being experienced, the maximum retry latency may be selected.

Abstract: A system on a chip for network devices. In one implementation, the system on a chip may include (integrated onto a single integrated circuit), a processor and one or more I/O devices for networking applications. For example, the I/O devices may include one or more network interface circuits for coupling to a network interface. In one embodiment, coherency may be enforced within the boundaries of the system on a chip but not enforced outside of the boundaries.

Abstract: An adaptive retry mechanism may record latencies of recent transactions (e.g. the first data transfer latency), and may select a retry latency from two or more retry latencies. The retry latency may be used for a transaction, and may specify a point in time during the transaction at which the transaction is retried if the first data transfer has not yet occurred. In one implementation, the set of retry latencies includes a minimum retry latency, a nominal retry latency, and a maximum retry latency. The nominal retry latency may be set slightly greater than the expected latency of transactions in the system. The minimum retry latency may be less than the nominal retry latency and the maximum retry latency may be greater than the nominal retry latency. If latencies greater than the nominal retry latency but less than the maximum retry latency are being experienced, the maximum retry latency may be selected.

Abstract: A cache is coupled to receive an access which includes a cache allocate indication. If the access is a miss in the cache, the cache either allocates a cache block storage location to store the cache block addressed by the access or does not allocate a cache block storage location in response to the cache allocate indication. In one implementation, the cache is coupled to an interconnect with one or more agents. In such an implementation, the cache accesses may be performed in response to transactions on the interconnect, and the transactions include the cache allocate indication. Thus, the source of a cache access specifies whether or not to allocate a cache block storage location in response to a miss by the cache access. The source may use a variety of mechanisms for generating the cache allocate indication.

Abstract: An apparatus includes a storage location and a write monitor circuit coupled to the storage location. The storage location is configured to store a write response indicator which is capable of indicating a reception of at least one write response. Each write response indicates that a corresponding write has reached a target device of that write. The write monitor circuit is configured to update the write response indicator in response to receiving an indication of a first write response. A computer accessible medium may comprises instructions which, when executed: (i) initialize the write response indicator; and (ii) issue one or more writes to a target device, wherein the target device is configured to response to each of the writes with a write response to be indicated by the write response indicator.

Abstract: An adaptive retry mechanism may record latencies of recent transactions (e.g. the first data transfer latency), and may select a retry latency from two or more retry latencies. The retry latency may be used for a transaction, and may specify a point in time during the transaction at which the transaction is retried if the first data transfer has not yet occurred. In one implementation, the set of retry latencies includes a minimum retry latency, a nominal retry latency, and a maximum retry latency. The nominal retry latency may be set slightly greater than the expected latency of transactions in the system. The minimum retry latency may be less than the nominal retry latency and the maximum retry latency may be greater than the nominal retry latency. If latencies greater than the nominal retry latency but less than the maximum retry latency are being experienced, the maximum retry latency may be selected.

Abstract: A cache is coupled to receive an access which includes a cache allocate indication. If the access is a miss in the cache, the cache either allocates a cache block storage location to store the cache block addressed by the access or does not allocate a cache block storage location in response to the cache allocate indication. In one implementation, the cache is coupled to an interconnect with one or more agents. In such an implementation, the cache accesses may be performed in response to transactions on the interconnect, and the transactions include the cache allocate indication. Thus, the source of a cache access specifies whether or not to allocate a cache block storage location in response to a miss by the cache access. The source may use a variety of mechanisms for generating the cache allocate indication.