Via Technologies, Inc.

Via Alliance Semiconductor Co., Ltd.

Jason Chen

G Glenn Henry

Rodney E Hooker

Darius D Gaskins

Douglas Raye Reed

Stephan Gaskins

A processor includes a cache memory having a plurality of entries. Each of the entries holds data of a cache line, a state of the cache line and a tag of the cache line. The cache memory includes an engine comprising one or more finite state machines. The processor also includes an interface to a bus over which the processor writes back modified cache lines from the cache memory to the system memory in response to encountering an architectural writeback and invalidate instruction. The processor also invalidates the state of the entries of the cache memory in response to encountering the architectural writeback and invalidate instruction. In response to being instructed to perform a cache diagnostic operation, for each entry of the entries, the engine writes the state and the tag of the entry on the bus and does not invalidate the state of the entry.

Cache memory diagnostic writeback

A method for debugging a multi-core microprocessor includes causing the microprocessor to perform an actual execution of instructions and obtaining from the microprocessor heartbeat information that specifies an actual execution sequence of the instructions by the plurality of cores relative to one another, commanding a corresponding plurality of instances of a software functional model of the cores to execute the instructions according to the actual execution sequence specified by the heartbeat information to generate simulated results of the execution of the instructions, and comparing the simulated results with actual results of the execution of the instructions to determine whether they match. Each core outputs an instruction execution indicator indicating the number of instructions executed by the core each core clock. A heartbeat generator generates a heartbeat indicator for each core on an external bus that indicates the number of instructions executed by each core during each external bus clock cycle.

Multi-core processor with external instruction execution rate heartbeat

A microprocessor is provided with a reset logic flag and corresponding reset microcode that selectively enables the reset microcode to set up and enable debug logic before the microprocessor subsequently fetches and executes user instructions. When the reset logic flag is set to a debug mode, the reset microcode configures and enables the microprocessor's debug logic before the microprocessor subsequently fetches and executes user instructions. When the reset logic flag is set to a normal mode, the reset microcode refrains from configuring and enabling the microprocessor's debug logic. The reset logic flag is indicated by an alterable fuse or a debugger-programmable scan register. Debug configuration initialization values are also provided by several alternative structures, including the reset microcode itself, alterable fuses, and debugger-programmable scan registers. Corresponding methods are also provided for configuring the debug logic of a microprocessor.

Tracer configuration and enablement by reset microcode

A microprocessor includes a bus interface unit that interfaces the microprocessor to a bus that includes a signal that, when asserted, instructs all bus agents to refrain from initiating bus transactions. Microcode causes the bus interface unit to assert the signal in response to detecting an event and resets the microprocessor, but does not reset a portion of the bus interface unit that asserts the signal on the bus. After the reset, the microcode causes the bus interface unit to deassert the signal on the bus. Additionally, the microcode sets a flag and saves the microprocessor state to memory before resetting itself, but does not reset the interrupt controller. After the reset, the microcode reloads the state of the microprocessor from the memory. However, if the microcode determines that the flag is set, it forgoes reloading the state of the interrupt controller.

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Austin, TX, United States of America

Jason Chen