Abstract: A coherency error detection and reporting mechanism monitors for coherency errors in a processor and between processors. When a requestor broadcasts a memory address in a command and a coherency error is detected, information regarding the command that caused the coherency error is logged, and the coherency error is reported a system error handler. The information logged for the coherency error may include the address of the coherency error, the requestor, the command, the response to the command, the scope of the coherency error, the error type, etc. Logging information relating to the coherency error provides more information to a person analyzing the processor for failures to more easily track down the cause of coherency errors.

Abstract: Reducing translation latency within a memory management unit (MMU) using external caching structures including requesting, by the MMU on a node, page table entry (PTE) data and coherent ownership of the PTE data from a page table in memory; receiving, by the MMU, the PTE data, a source flag, and an indication that the MMU has coherent ownership of the PTE data, wherein the source flag identifies a source location of the PTE data; performing a lateral cast out to a local high-level cache on the node in response to determining that the source flag indicates that the source location of the PTE data is external to the node; and directing at least one subsequent request for the PTE data to the local high-level cache.

Abstract: Reducing translation latency within a memory management unit (MMU) using external caching structures including requesting, by the MMU on a node, page table entry (PTE) data and coherent ownership of the PTE data from a page table in memory; receiving, by the MMU, the PTE data, a source flag, and an indication that the MMU has coherent ownership of the PTE data, wherein the source flag identifies a source location of the PTE data; performing a lateral cast out to a local high-level cache on the node in response to determining that the source flag indicates that the source location of the PTE data is external to the node; and directing at least one subsequent request for the PTE data to the local high-level cache.

Abstract: A serial communication system includes a transmitting circuit for serially transmitting data via a serial communication link including N channels where N is an integer greater than 1. The transmitting circuit includes an input buffer having storage for input data frames each including M bytes forming N segments of M/N contiguous bytes. The transmitting circuit additionally includes a reordering circuit coupled to the input buffer. The reordering circuit includes a reorder buffer including multiple entries. The reordering circuit buffers, in each of multiple entries of the reorder buffer, a byte in a common byte position in each of the N segments of an input data frame. The reordering circuit sequentially outputs the contents of the entries of the reorder buffer via the N channels of the serial communication link.

Abstract: A technique for handling interrupts in a data processing system includes receiving, by an interrupt routing controller (IRC), an event routing message (ERM) that includes an event source number for a notification source with an unserviced interrupt. In response to receiving the ERM, the IRC builds an event notification message (ENM) based on the event source number. The IRC determines a scope for the ENM based on an event target group (ETG) associated with the event source number. The IRC issues the ENM to an interrupt presentation controller (IPC) at the scope associated with the ETG.

Abstract: A technique for operating a data processing system includes transitioning, by a cache, to a highest point of coherency (HPC) for a cache line in a required state without receiving data for one or more segments of the cache line that are needed. The cache issues a command to a lowest point of coherency (LPC) that requests data for the one or more segments of the cache line that were not received and are needed. The cache receives the data for the one or more segments of the cache line from the LPC that were not previously received and were needed.

Abstract: A technique for operating a data processing system includes detecting that a processing unit within a first group of processing units in the data processing system has a hang condition. In response to detecting that the processing unit has a hang condition, a command issue rate for the first group of processing units is reduced. One or more other groups of processing units in the data processing system are notified that the first group of processing units has reduced the command issue rate for the first group of processing units. In response to the notifying, respective command issue rates of the other groups of processing units are reduced to reduce a number of commands received by the first group of processing units from the other groups of processing units.

Abstract: A technique for handling interrupts in a data processing system includes receiving, by an interrupt routing controller (IRC), an event routing message (ERM) that includes an event source number for a notification source with an unserviced interrupt. In response to receiving the ERM, the IRC builds an event notification message (ENM) based on the event source number. The IRC determines a scope for the ENM based on an event target group (ETG) associated with the event source number. The IRC issues the ENM to an interrupt presentation controller (IPC) at the scope associated with the ETG.

Abstract: A technique for handling interrupts in a data processing system includes receiving, by an interrupt routing controller (IRC), an event routing message (ERM) that includes an event source number for a notification source with an unserviced interrupt. In response to receiving the ERM, the IRC builds an event notification message (ENM) based on the event source number. The IRC determines a scope for the ENM based on an event target group (ETG) associated with the event source number. The IRC issues the ENM to an interrupt presentation controller (IPC) at the scope associated with the ETG.

Abstract: A multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and a system interconnect coupled to the system memory and the multiple vertical cache hierarchies. A first cache memory in a first vertical cache hierarchy issues on the system interconnect a request for a target cache line. Responsive to the request and prior to receiving a systemwide coherence response for the request, the first cache memory receives from a second cache memory in a second vertical cache hierarchy by cache-to-cache intervention the target cache line and an early indication of the systemwide coherence response for the request. In response to the early indication of the systemwide coherence response and prior to receiving the systemwide coherence response, the first cache memory initiates processing to install the target cache line in the first cache memory.

Abstract: A coherency error detection and reporting mechanism monitors for coherency errors in a processor and between processors. When a requestor broadcasts a memory address in a command and a coherency error is detected, information regarding the command that caused the coherency error is logged, and the coherency error is reported a system error handler. The information logged for the coherency error may include the address of the coherency error, the requestor, the command, the response to the command, the scope of the coherency error, the error type, etc. Logging information relating to the coherency error provides more information to a person analyzing the processor for failures to more easily track down the cause of coherency errors.

Abstract: An integrated circuit includes a transmitting circuit configured to be coupled to a physical serial interface having a bit width. The transmitting circuit is configured to transmit, via the physical serial interface, a frame including multiple aligned flits all of an equal fixed length that is an integer multiple of the bit width of the physical serial interface. The multiple flits include both a control flit specifying at least a command to be performed by a recipient of the command and a data flit providing data to be operated upon through performance of the command. The control flit includes a data protection code computed over the control flit and a data flit of a previously transmitted frame.

Abstract: A serial communication system includes a transmitting circuit for serially transmitting data via a serial communication link including N channels where N is an integer greater than 1. The transmitting circuit includes an input buffer having storage for input data frames each including M bytes forming N segments of M/N contiguous bytes. The transmitting circuit additionally includes a reordering circuit coupled to the input buffer. The reordering circuit includes a reorder buffer including multiple entries. The reordering circuit buffers, in each of multiple entries of the reorder buffer, a byte in a common byte position in each of the N segments of an input data frame. The reordering circuit sequentially outputs the contents of the entries of the reorder buffer via the N channels of the serial communication link.

Abstract: A multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and a system interconnect coupled to the system memory and the multiple vertical cache hierarchies. A first cache memory in a first vertical cache hierarchy issues on the system interconnect a request for a target cache line. Responsive to the request and prior to receiving a systemwide coherence response for the request, the first cache memory receives from a second cache memory in a second vertical cache hierarchy by cache-to-cache intervention the target cache line and an early indication of the systemwide coherence response for the request. In response to the early indication of the systemwide coherence response and prior to receiving the systemwide coherence response, the first cache memory initiates processing to install the target cache line in the first cache memory.

Abstract: A data structure includes a plurality of entries each corresponding to a different systemwide combined response of a data processing system. A particular entry includes identifiers of multiple possible actions that can be taken in response to a systemwide combined response. Master logic issues a memory access request on a system fabric of the data processing system. The master logic, responsive to receiving the systemwide combined response and a selection of one of the multiple possible actions from a source of the memory access request prior to receipt of the systemwide combined response, selects the particular entry based on the systemwide combined response and selects one of the multiple possible actions identified in the particular entry based on the received selection. The master logic services the memory access request in accordance with the systemwide combined response by performing the selected one of the multiple possible actions.

Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can continually increase a command rate of an interconnect if one or more requests to lower the command rate are not received within one or more periods of time. In one example, the command rate can be set to a fastest level. In another example, the command rate can be incrementally increased over periods of time. If a request to lower the command rate is received, the command rate can be set to a reference level or can be decremented to one slower rate level. In one or more embodiments, the one or more requests to lower the command rate can be based on at least one of an issue rate of speculative commands and a number of overcommit failures, among others.

Abstract: A data structure includes a plurality of entries each corresponding to a different systemwide combined response of a data processing system. A particular entry includes identifiers of multiple possible actions that can be taken in response to a systemwide combined response. Master logic issues a memory access request on a system fabric of the data processing system. The master logic, responsive to receiving the systemwide combined response and a selection of one of the multiple possible actions from a source of the memory access request prior to receipt of the systemwide combined response, selects the particular entry based on the systemwide combined response and selects one of the multiple possible actions identified in the particular entry based on the received selection. The master logic services the memory access request in accordance with the systemwide combined response by performing the selected one of the multiple possible actions.

Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can send, via an interconnect, a rate master command to at least one of multiple processing nodes; determine that a message indicating a dropped command, associated with the rate master command, is received; determine that a count, associated with dropped commands, satisfies a threshold; and provide, to the processing nodes via the interconnect, a signal indicating a command rate, in response to determining that the count satisfies the threshold. Moreover, the count can be incremented in response to determining that the message is received. The at least one of multiple processing nodes can receive, via the interconnect, the signal indicating the command rate and can utilize the command rate in issuing speculative commands, via the interconnect.

Abstract: In one or more embodiments, one or more systems, devices, methods, and/or processes described can send, via an interconnect, a rate master command to at least one of multiple processing nodes; determine that a message indicating a dropped command, associated with the rate master command, is received; determine that a count, associated with dropped commands, satisfies a threshold; and provide, to the processing nodes via the interconnect, a signal indicating a command rate, in response to determining that the count satisfies the threshold. Moreover, the count can be incremented in response to determining that the message is received. The at least one of multiple processing nodes can receive, via the interconnect, the signal indicating the command rate and can utilize the command rate in issuing speculative commands, via the interconnect.

Abstract: An integrated circuit system including a first integrated circuit chip including first logic, a second integrated circuit chip, and second logic distributed across the first and second integrated circuit chips. The second logic includes a first unit integrated in the first integrated circuit chip and a second unit integrated in the second integrated circuit chip. The integrated circuit system further includes a physical communication link coupling the first unit in the first integrated circuit chip and the second unit in the second integrated circuit chip and a request interface between the first logic and first unit of the second logic. The request interface is implemented in the first integrated circuit such that communication via the request interface between the first logic and the first unit of the second logic has low latency and such that the request interface is decoupled from the physical communication link.