Architectures and Processors

ARM Cortex-R52 PMU Register Ambiguities and Missing Reset Values The ARM Cortex-R52 processor, specifically revision r1p1, incorporates a Performance Monitoring Unit (PMU) that is critical for profiling and optimizing system performance. However, the documentation for the PMU registers, particularly in the context of PMU v3, is incomplete. Key issues include the use of "UNK" (unknown)…

ARM Cortex-M4 MPU Configuration Causing Memory Management Faults Memory Management Fault Triggered by IACCVIOL Bit Set When enabling the Memory Protection Unit (MPU) on an ARM Cortex-M4 processor, such as the one found in the STM32F4 microcontroller family, a common issue arises where a Memory Management Fault is triggered. This fault is often indicated by…

ARM MPU Region Limitations and Stack Protection Challenges The ARM Memory Protection Unit (MPU) is a critical component for ensuring memory safety and access control in embedded systems. However, its practical implementation often reveals complexities, particularly in multi-threaded environments with stringent memory partitioning requirements. The MPU provides a finite number of regions (typically 8 to…

Dual-Core Cortex-M7 Lockstep Configuration for Automotive Safety Applications The Cortex-M7 processor, known for its high performance and efficiency, is widely used in embedded systems, including automotive applications. However, when it comes to functional safety, particularly in automotive safety-critical systems, the need for redundancy and error detection becomes paramount. One of the most effective ways to…

ARM Architecture’s Fragmented RNG Implementation Landscape The ARM architecture, while widely adopted across various embedded systems and processors, suffers from a fragmented implementation of hardware random number generators (RNGs). Unlike x86 architectures where Intel and AMD have standardized instructions like RDRAND, ARM’s approach to RNGs is inconsistent and vendor-specific. This fragmentation manifests in several ways,…

ARM Cortex-A72 Incorrectly Interpreting IRQ Handler Opcode as Address The issue revolves around the ARM Cortex-A72 core incorrectly interpreting the opcode of the IRQ handler as an address during an interrupt request (IRQ) event. When an IRQ is triggered, the core branches to the default IRQ vector address at 0x18 (with V=0 and VE=0). The…

ARM Cortex-A53 Inner Shareable Domain Hierarchy and Cache Policy Configuration The ARM Cortex-A53 processor, part of the ARMv8-A architecture, introduces a complex memory hierarchy with multiple levels of caches and shareable domains. Understanding the inner shareable domain and its relationship with cache policies is critical for optimizing performance and ensuring data consistency in multi-core systems….

ARM VMSAv8-32 Address Translation and Virtual Address Bit Allocation The ARM VMSAv8-32 architecture employs a multi-level page table structure to translate virtual addresses (VA) to physical addresses (PA). This translation process is critical for memory management in ARM-based systems, ensuring efficient and secure access to memory resources. The specific allocation of virtual address bits for…

Bootloader Relocation Challenges in ARM Cortex-M3: Absolute Addressing and Interrupt Vector Handling Relocating a bootloader from Flash to RAM on an ARM Cortex-M3 processor, such as the STM32F103RB, presents several technical challenges. The primary issue revolves around the presence of absolute addresses in the compiled code, which complicates the relocation process. While the ARM Cortex-M3…

Configuring Non-Cacheable Memory Regions via MMU for Direct RAM Writes The ARM Cortex-A53 processor, like many modern processors, employs a memory hierarchy that includes caches and store buffers to optimize performance. However, certain applications, such as real-time systems or specific research scenarios, may require data to be written directly to RAM, bypassing these optimizations. To…