Cortex-R52 GICv3 Interrupt Handling Sequence and Stack Overflow The Cortex-R52 processor, when paired with a GICv3 interrupt controller, can experience a critical issue during interrupt handling where the processor fails to restore the context after handling an interrupt. This issue manifests when interrupts are triggered frequently, and the IRQ is unmasked before writing to the…
ARM Cortex-A76 and DSU Cache Way Partitioning Misbehavior Cache way partitioning is a critical feature in modern ARM processors, particularly in multi-core systems where shared resources like the Last Level Cache (LLC) must be managed efficiently to ensure predictable performance. The ARM Cortex-A76, coupled with the DynamIQ Shared Unit (DSU), supports cache way partitioning to…
Understanding the UD State and MakeInvalid Transaction Requirements The ARM AMBA Coherent Hub Interface (CHI) specification defines a set of cache states and transactions that ensure coherency across multiple request nodes (RNs) in a system. One such state is the UD (Unique Dirty) state, which indicates that the cache line is held exclusively by the…
L2 Cache ECC Single-Bit Correctable Error Notification Mechanism The ARM Cortex-A72 processor incorporates Error Correction Code (ECC) mechanisms within its L2 cache to detect and correct memory errors. ECC is critical for ensuring data integrity, particularly in safety-critical and high-reliability systems. The Cortex-A72 L2 cache ECC system can handle both single-bit correctable errors and double-bit…
Memory Reconstruction Port: Purpose and Role in Cortex-R Processors The Memory Reconstruction Port (MRP) in ARM Cortex-R series processors is a specialized feature designed to facilitate advanced debugging and system recovery scenarios, particularly in safety-critical and real-time embedded systems. The MRP allows external access to the processor’s internal memory and system state, even when the…
ARM Cortex-M4 Stack Pointer Misalignment During Task Initialization The ARM Cortex-M4 processor, like other ARMv7-M architecture-based processors, enforces strict alignment requirements for stack pointers. The stack pointer (SP) must always be aligned to an 8-byte boundary, as mandated by the ARM Architecture Reference Manual. Misalignment of the stack pointer can lead to unpredictable behavior, including…
Cortex-M7 UsageFault Handler Misrouting Due to Incorrect Link Register Management The core issue revolves around the improper handling of the Link Register (LR) during exception handling in an ARM Cortex-M7 microcontroller. Specifically, the problem manifests when attempting to return from a UsageFault exception triggered by an unaligned memory access. The handler, UsageFault_Handler, is designed to…
Clock Configuration and Runtime Initialization Hangs in STM32F411 The core issue revolves around an STM32F411 microcontroller where the firmware executes correctly only when stepped through a debugger but fails to run in Release mode. The problem manifests during the clock configuration phase, specifically when the microcontroller attempts to initialize the High-Speed Internal (HSI) clock, configure…
ARM Cortex-R52+ Branch Prediction and NVM Access Conflicts The Cortex-R52+ processor, like many modern ARM cores, employs advanced features such as branch prediction, speculative execution, and prefetching to optimize performance. However, these features can lead to unintended side effects when interacting with Non-Volatile Memory (NVM), particularly during Read-While-Write (RWW) operations. In this scenario, the core…
ARM Cortex-R8 QoS Feature and Address Filtering Constraints The ARM Cortex-R8 processor is a high-performance, real-time capable processor designed for applications requiring deterministic behavior and high throughput. One of its advanced features is the Quality of Service (QoS) capability, which allows for prioritization of memory transactions to ensure that critical tasks receive the necessary bandwidth…