ARM CHI Spec Address Alignment Rules for Normal vs. Device Memory The ARM Coherent Hub Interface (CHI) specification defines distinct address alignment rules for normal memory and device memory. These differences arise from the inherent characteristics and usage patterns of each memory type. Normal memory, typically used for general-purpose data storage and processing, follows a…
ARM Processors with Hardware H.264 Encoder: Identifying Suitable Replacements for i.MX 6 The i.MX 6 series has been a popular choice for embedded systems requiring hardware H.264 encoding capabilities. However, with the i.MX 6 reaching its end-of-life (EOL), developers and engineers are now seeking alternative ARM-based processors that offer similar or better performance, particularly in…
PMCCNTR_EL0 Register Reads Zero Despite Proper Initialization The core issue revolves around the Performance Monitor Counter Register (PMCCNTR_EL0) on the ARM Cortex-A72 processor not incrementing or returning a value of zero when read, despite seemingly correct initialization of the Performance Monitor Unit (PMU) registers. This issue is critical for developers relying on the PMU for…
ARM Cortex-A55 Branch Predictor Behavior and Speculative Access Risks The ARM Cortex-A55 is a highly efficient, mid-range CPU core designed for power-efficient performance in embedded systems and mobile devices. One of its key features is the branch predictor, which enhances performance by speculatively executing instructions likely to be needed next. However, this speculative execution raises…
ARM Cortex-A5 Soft Core Availability for Xilinx Ultrascale+ FPGAs The integration of ARM Cortex-A5 soft cores into Xilinx Ultrascale+ FPGAs presents a unique set of challenges and opportunities for embedded systems engineers. The Cortex-A5, being a member of the ARM Cortex-A family, is designed for high-performance applications, making it an attractive option for FPGA-based designs….
ARM Cortex-M7 LDREX Instruction Causing Bus Fault in Multi-Core Environment The ARM Cortex-M7 processor is a high-performance embedded processor designed for real-time applications. One of its key features is support for exclusive access instructions, such as LDREX (Load Exclusive) and STREX (Store Exclusive), which are used to implement atomic operations in multi-core or multi-threaded environments….
ARM64 Cache Management: The Need for flush_dcache_range in Kernel Modules In ARM64 architectures, managing cache coherency is a critical aspect of ensuring correct and efficient system operation, particularly when dealing with Direct Memory Access (DMA) operations, shared memory regions, or custom kernel modules. The absence of a globally exported flush_dcache_range function in earlier Linux kernel…
ARM Cortex-A/R Profile Interrupt Masking Behavior During Exceptions When an interrupt exception occurs on ARM Cortex-A or Cortex-R profile processors, the processor automatically modifies the Current Program Status Register (CPSR) in AArch32 or PSTATE in AArch64 to mask further interrupts. This automatic masking is a fundamental aspect of ARM’s exception handling architecture designed to ensure…
SWO Feature Implementation Challenges in Coresight SOC 400 TPIU The integration of the Single Wire Output (SWO) feature into a System on Chip (SoC) design that already includes a Cortex-M7 processor and a Coresight SOC 400 Trace Port Interface Unit (TPIU) presents a unique set of challenges. The primary issue revolves around the fact that…
ARM Cortex-M7 FFT Performance Challenges with SIMD Utilization The ARM Cortex-M7 processor, known for its high performance in embedded applications, is often utilized for digital signal processing (DSP) tasks such as the Fast Fourier Transform (FFT). The Cortex-M7’s Single Instruction Multiple Data (SIMD) capabilities, particularly through its DSP extension instructions, offer significant potential for accelerating…