Abstract: A method includes determining, by a level one (L1) controller, to change a size of a L1 main cache; servicing, by the L1 controller, pending read requests and pending write requests from a central processing unit (CPU) core; stalling, by the L1 controller, new read requests and new write requests from the CPU core; writing back and invalidating, by the L1 controller, the L1 main cache. The method also includes receiving, by a level two (L2) controller, an indication that the L1 main cache has been invalidated and, in response, flushing a pipeline of the L2 controller; in response to the pipeline being flushed, stalling, by the L2 controller, requests received from any master; reinitializing, by the L2 controller, a shadow L1 main cache. Reinitializing includes clearing previous contents of the shadow L1 main cache and changing the size of the shadow L1 main cache.

Abstract: A system comprises a processor including a CPU core, first and second memory caches, and a memory controller subsystem. The memory controller subsystem speculatively determines a hit or miss condition of a virtual address in the first memory cache and speculatively translates the virtual address to a physical address. Associated with the hit or miss condition and the physical address, the memory controller subsystem configures a status to a valid state. Responsive to receipt of a first indication from the CPU core that no program instructions associated with the virtual address are needed, the memory controller subsystem reconfigures the status to an invalid state and, responsive to receipt of a second indication from the CPU core that a program instruction associated with the virtual address is needed, the memory controller subsystem reconfigures the status back to a valid state.

Abstract: An apparatus includes a CPU core and a L1 cache subsystem including a L1 main cache, a L1 victim cache, and a L1 controller. The apparatus includes a L2 cache subsystem coupled to the L1 cache subsystem by a transaction bus and a tag update bus. The L2 cache subsystem includes a L2 main cache, a shadow L1 main cache, a shadow L1 victim cache, and a L2 controller. The L2 controller receives a message from the L1 controller over the tag update bus, including a valid signal, an address, and a coherence state. In response to the valid signal being asserted, the L2 controller identifies an entry in the shadow L1 main cache or the shadow L1 victim cache having an address corresponding to the address of the message and updates a coherence state of the identified entry to be the coherence state of the message.

Abstract: A method includes receiving, by a L2 controller, a request to perform a global operation on a L2 cache and preventing new blocking transactions from entering a pipeline coupled to the L2 cache while permitting new non-blocking transactions to enter the pipeline. Blocking transactions include read transactions and non-victim write transactions. Non-blocking transactions include response transactions, snoop transactions, and victim transactions.

Abstract: An apparatus includes first CPU and second CPU cores, a L1 cache subsystem coupled to the first CPU core and comprising a L1 controller, and a L2 cache subsystem coupled to the L1 cache subsystem and to the second CPU core. The L2 cache subsystem includes a L2 memory and a L2 controller configured to operate in an aliased mode in response to a value in a memory map control register being asserted. In the aliased mode, the L2 controller receives a first request from the first CPU core directed to a virtual address in the L2 memory, receives a second request from the second CPU core directed to the virtual address in the L2 memory, directs the first request to a physical address A in the L2 memory, and directs the second request to a physical address B in the L2 memory.

Abstract: A method includes receiving, by a level two (L2) controller, a write request for an address that is not allocated as a cache line in a L2 cache. The write request specifies write data. The method also includes generating, by the L2 controller, a read request for the address; reserving, by the L2 controller, an entry in a register file for read data returned in response to the read request; updating, by the L2 controller, a data field of the entry with the write data; updating, by the L2 controller, an enable field of the entry associated with the write data; and receiving, by the L2 controller, the read data and merging the read data into the data field of the entry.

Abstract: A method includes receiving, by a level two (L2) controller, a first request for a cache line in a shared cache coherence state; mapping, by the L2 controller, the first request to a second request for a cache line in an exclusive cache coherence state; and responding, by the L2 controller, to the second request.

Abstract: An apparatus includes a central processing unit (CPU) core and a cache subsystem coupled to the CPU core. The cache subsystem includes a memory configured to store a line of data and an error correcting code (ECC) syndrome associated with the line of data, where the ECC syndrome is calculated based on the line of data and the ECC syndrome is a first type ECC. The cache subsystem also includes a controller configured to, in response to a request from a master configured to implement a second type ECC, the request being directed to the line of data, transform the first type ECC syndrome for the line of data to a second type ECC syndrome send a response to the master. The response includes the line of data and the second type ECC syndrome associated with the line of data.

Abstract: In described examples, a processor system includes a processor core that generates memory write requests, a cache memory, and a memory pipeline of the cache memory. The memory pipeline has a holding buffer, an anchor stage, and an RMW pipeline. The anchor stage determines whether a data payload of a write request corresponds to a partial write. If so, the data payload is written to the holding buffer and conforming data is read from a corresponding cache memory address to merge with the data payload. The RMW pipeline has a merge stage and a syndrome generation stage. The merge stage merges the data payload in the holding buffer with the conforming data to make merged data. The syndrome generation stage generates an ECC syndrome using the merged data. The memory pipeline writes the data payload and ECC syndrome to the cache memory.

Abstract: In described examples, a coherent memory system includes a central processing unit (CPU) and first and second level caches. The memory system can include a pipeline for accessing data stored in one of the caches. Requestors can access the data stored in one of the caches by sending requests at a same time that can be arbitrated by the pipeline.

Abstract: A system comprises a processor including a CPU core, first and second memory caches, and a memory controller subsystem. The memory controller subsystem speculatively determines a hit or miss condition of a virtual address in the first memory cache and speculatively translates the virtual address to a physical address. Associated with the hit or miss condition and the physical address, the memory controller subsystem configures a status to a valid state. Responsive to receipt of a first indication from the CPU core that no program instructions associated with the virtual address are needed, the memory controller subsystem reconfigures the status to an invalid state and, responsive to receipt of a second indication from the CPU core that a program instruction associated with the virtual address is needed, the memory controller subsystem reconfigures the status back to a valid state.

Abstract: A method includes determining, by a level one (L1) controller, to change a size of a L1 main cache; servicing, by the L1 controller, pending read requests and pending write requests from a central processing unit (CPU) core; stalling, by the L1 controller, new read requests and new write requests from the CPU core; writing back and invalidating, by the L1 controller, the L1 main cache. The method also includes receiving, by a level two (L2) controller, an indication that the L1 main cache has been invalidated and, in response, flushing a pipeline of the L2 controller; in response to the pipeline being flushed, stalling, by the L2 controller, requests received from any master; reinitializing, by the L2 controller, a shadow L1 main cache. Reinitializing includes clearing previous contents of the shadow L1 main cache and changing the size of the shadow L1 main cache.

Abstract: An apparatus includes a CPU core and a L1 cache subsystem including a L1 main cache, a L1 victim cache, and a L1 controller. The apparatus includes a L2 cache subsystem coupled to the L1 cache subsystem by a transaction bus and a tag update bus. The L2 cache subsystem includes a L2 main cache, a shadow L1 main cache, a shadow L1 victim cache, and a L2 controller. The L2 controller receives a message from the L1 controller over the tag update bus, including a valid signal, an address, and a coherence state. In response to the valid signal being asserted, the L2 controller identifies an entry in the shadow L1 main cache or the shadow L1 victim cache having an address corresponding to the address of the message and updates a coherence state of the identified entry to be the coherence state of the message.

Abstract: A method includes receiving, by a L2 controller, a request to perform a global operation on a L2 cache and preventing new blocking transactions from entering a pipeline coupled to the L2 cache while permitting new non-blocking transactions to enter the pipeline. Blocking transactions include read transactions and non-victim write transactions. Non-blocking transactions include response transactions, snoop transactions, and victim transactions.

Abstract: An apparatus includes a CPU core and a L1 cache subsystem including a L1 main cache, a L1 victim cache, and a L1 controller. The apparatus includes a L2 cache subsystem including a L2 main cache, a shadow L1 main cache, a shadow L1 victim cache, and a L2 controller configured to receive a read request from the L1 controller as a single transaction. Read request includes a read address, a first indication of an address and a coherence state of a cache line A to be moved from the L1 main cache to the L1 victim cache to allocate space for data returned in response to the read request, and a second indication of an address and a coherence state of a cache line B to be removed from the L1 victim cache in response to the cache line A being moved to the L1 victim cache.

Abstract: An apparatus includes a CPU core, a first memory cache with a first line size, and a second memory cache having a second line size larger than the first line size. Each line of the second memory cache includes an upper half and a lower half. A memory controller subsystem is coupled to the CPU core and to the first and second memory caches. Upon a miss in the first memory cache for a first target address, the memory controller subsystem determines that the first target address resulting in the miss maps to the lower half of a line in the second memory cache, retrieves the entire line from the second memory cache, and returns the entire line from the second memory cache to the first memory cache.

Abstract: An apparatus includes a central processing unit (CPU) core and a cache subsystem coupled to the CPU core. The cache subsystem includes a memory configured to store a line of data and an error correcting code (ECC) syndrome associated with the line of data, where the ECC syndrome is calculated based on the line of data and the ECC syndrome is a first type ECC. The cache subsystem also includes a controller configured to, in response to a request from a master configured to implement a second type ECC, the request being directed to the line of data, transform the first type ECC syndrome for the line of data to a second type ECC syndrome send a response to the master. The response includes the line of data and the second type ECC syndrome associated with the line of data.

Abstract: A method includes receiving, by a level two (L2) controller, a first request for a cache line in a shared cache coherence state; mapping, by the L2 controller, the first request to a second request for a cache line in an exclusive cache coherence state; and responding, by the L2 controller, to the second request.

Abstract: In described examples, a processor system includes a processor core that generates memory write requests, a cache memory, and a memory pipeline of the cache memory. The memory pipeline has a holding buffer, an anchor stage, and an RMW pipeline. The anchor stage determines whether a data payload of a write request corresponds to a partial write. If so, the data payload is written to the holding buffer and conforming data is read from a corresponding cache memory address to merge with the data payload. The RMW pipeline has a merge stage and a syndrome generation stage. The merge stage merges the data payload in the holding buffer with the conforming data to make merged data. The syndrome generation stage generates an ECC syndrome using the merged data. The memory pipeline writes the data payload and ECC syndrome to the cache memory.

Abstract: In described examples, a processor system includes a processor core generating memory transactions, a lower level cache memory with a lower memory controller, and a higher level cache memory with a higher memory controller having a memory pipeline. The higher memory controller is connected to the lower memory controller by a bypass path that skips the memory pipeline. The higher memory controller: determines whether a memory transaction is a bypass write, which is a memory write request indicated not to result in a corresponding write being directed to the higher level cache memory; if the memory transaction is determined a bypass write, determines whether a memory transaction that prevents passing is in the memory pipeline; and if no transaction that prevents passing is determined to be in the memory pipeline, sends the memory transaction to the lower memory controller using the bypass path.