Architectures and Processors

Cortex-A35 Feature Configuration and ATF Initialization Challenges The ARM Cortex-A35 is a highly efficient processor designed for power-sensitive applications, offering a balance between performance and energy efficiency. However, its flexibility in feature configuration can sometimes lead to unexpected behavior during system initialization, particularly when working with the ARM Trusted Firmware (ATF). The ATF is responsible…

Ethos-U55 MAC and Elementwise Engine Concurrency Challenges The Ethos-U55 Neural Processing Unit (NPU) is a highly optimized accelerator designed for machine learning workloads, featuring specialized engines such as the Multiply-Accumulate (MAC) Engine and the Elementwise Engine. These engines are designed to handle specific types of operations efficiently. However, a critical question arises regarding their ability…

EL3 to Non-Secure EL1 Transition Failure and Missing EL1 Entry Call When transitioning from EL3 (Exception Level 3) to non-secure EL1 (Exception Level 1) on an ARM Cortex-A55 processor, the CPU successfully switches to EL1h (non-secure mode), but the el1_entry function is never called. This issue is particularly perplexing because the same code works when…

CoreSight Device Enumeration Failure on Nvidia Jetson Nano and AGX Xavier The CoreSight debugging and tracing infrastructure is a critical component for developers working on ARM-based systems, enabling real-time tracing, profiling, and debugging of complex software and hardware interactions. However, when attempting to use CoreSight on Nvidia Jetson platforms such as the Jetson Nano and…

ARM Cortex-R52+ Floating-Point Register Corruption During Interrupt Handling The ARM Cortex-R52+ is a high-performance real-time processor designed for safety-critical applications. One of its key features is the support for floating-point operations, which are essential for tasks requiring precision calculations. However, in certain scenarios, particularly when dealing with interrupts and context switching, floating-point register corruption can…

Cortex-A78 and ArmRAL: Understanding the Compatibility and Performance Implications The Cortex-A78, a high-performance processor based on the ARMv8.2-A architecture, is widely used in applications requiring significant computational power, such as SmartNICs. ArmRAL (Arm RAN Acceleration Library) is a critical tool for accelerating 5G NR signal processing workloads, leveraging vector engines like Neon, SVE, and SVE2….

Unaligned AXI4 Transfers and Their Impact on Data Integrity Unaligned transfers in the AXI4 protocol present unique challenges, particularly when dealing with start addresses that are not aligned with the transfer size. In the scenario described, a 32-bit transfer begins at address 0x01, which is unaligned for a 4-byte transfer. This misalignment affects how data…

ARM Cortex-R52 MPU Configuration Conflict: Device vs. Normal Memory Type Mismatch The ARM Cortex-R52 processor, designed for real-time and safety-critical applications, employs a Memory Protection Unit (MPU) to enforce memory access rules and attributes. One of the critical features of the MPU is its ability to define memory regions with specific attributes, such as Device…

ARM Cortex-A72 and A78 Register Definition Extraction from TRMs The process of extracting register definitions from ARM Cortex-A72 and A78 Technical Reference Manuals (TRMs) presents a significant challenge for engineers tasked with supporting multiple ARM cores. The primary issue revolves around the lack of machine-readable formats for TRMs, which forces developers to resort to parsing…

ARM SME Assembly: Challenges with F64 Outer Product Calculations The Scalable Matrix Extension (SME) in ARM architectures introduces powerful capabilities for matrix operations, including outer product calculations. However, implementing floating-point 64-bit (F64) outer products in SME assembly can be challenging due to the complexity of the instruction set, the need for precise memory management, and…