Architectures and Processors

ARM Cortex-A8 NEON memcpy() Hangs During DMA Buffer Operations The ARM Cortex-A8 processor, known for its efficient handling of multimedia and signal processing tasks, leverages the NEON SIMD (Single Instruction, Multiple Data) engine to accelerate data-intensive operations. However, when using NEON instructions to perform memory copy operations (memcpy()) into a DMA (Direct Memory Access) buffer,…

ARM Processor Identification and Cache Configuration Challenges When working with ARM-based systems, particularly in environments like RedHat Linux, developers often face challenges in accurately identifying the processor type and retrieving detailed cache configuration information. Unlike x86 systems, where the CPUID instruction provides a straightforward method to obtain processor family, model, and cache details, ARM architectures…

Understanding RK3399 Core Configuration and Compute Library Constraints The RK3399 SoC features a big.LITTLE architecture, combining high-performance Cortex-A72 cores with power-efficient Cortex-A53 cores. When leveraging the ARM Compute Library for inference tasks, developers often need to restrict execution to specific cores, such as the Cortex-A53, to measure performance, optimize power consumption, or isolate workloads. However,…

ARM Cortex-M1 Address Skipping and Random Memory Access Behavior The core issue revolves around the ARM Cortex-M1 soft processor exhibiting unexpected memory access patterns when running a simple C program on the PYNQ-Z2 platform. Specifically, the processor skips expected memory addresses (e.g., skipping address 0x08) and accesses random memory locations during array read operations. This…

ARM Cortex-M Stack Pointer Initialization in Reset_Handler The initialization of the stack pointer (SP) in ARM Cortex-M microcontrollers, such as the STM32 series, is a critical step in the boot process. The stack pointer is typically set in the Reset_Handler function within the startup file (e.g., startup_stm32f446xx.s). This initialization is done using the instruction ldr…

ARMv7 Memory Access Ordering: Strongly Ordered vs. Normal Memory In ARMv7 architectures, memory types are categorized into Normal, Device, and Strongly Ordered (SO) memory. Each type has distinct characteristics regarding access ordering, caching, and buffering. Normal memory is typically used for general-purpose data and code storage, where the ARM processor can optimize performance through reordering,…

ARM Cortex-M4 and Cortex-M0 CIDR/PIDR Decoding Challenges When working with ARM Cortex-M series processors, particularly the Cortex-M4 and Cortex-M0, identifying Generic IP components through Component Identification Registers (CIDR) and Peripheral Identification Registers (PIDR) can be a complex task. The CIDR and PIDR registers are essential for distinguishing between CoreSight components and Generic IP components. However,…

ARM Cortex-A72 Multi-Core AXI Read Transaction Attribution Challenges In multi-core ARM Cortex-A72 systems, one of the most intricate challenges is determining which core is generating a specific AXI read transaction. This issue arises due to the shared AXI read channel among all cores, which complicates the process of attributing transactions to their respective cores. When…

ARM Cortex-M4 Context Switching and INVPC Usage Fault Overview The ARM Cortex-M4 processor is widely used in embedded systems for its balance of performance and power efficiency. One of its key features is the ability to handle exceptions and interrupts efficiently, which is crucial for real-time operating systems (RTOS) and context switching. However, improper handling…

Cortex-M Event Register Behavior During Interrupt Handling with SEVONPEND Enabled The Cortex-M architecture provides a robust mechanism for handling interrupts and events, which is critical for real-time embedded systems. One of the key features in this context is the Event Register, which plays a pivotal role in managing low-power modes and interrupt-driven workflows. When the…