ARM Cortex-A55 Baremetal Boot: EL1 to EL0 Transition Challenges When working with the ARM Cortex-A55 processor in a baremetal environment, transitioning between exception levels (ELs) is a critical part of setting up the execution environment. The Cortex-A55, based on the ARMv8-A architecture, supports four exception levels: EL0 (user mode), EL1 (OS kernel mode), EL2 (hypervisor…
AXI5 Atomic Transaction Mechanics and Write Data-Address Ordering The AXI5 protocol, an evolution of the Advanced eXtensible Interface (AXI) standard, is widely used in ARM-based systems for high-performance, low-latency communication between components. One of its advanced features is support for atomic transactions, which ensure that certain operations are executed without interruption, maintaining data consistency in…
AHB Subordinate HREADY Signal Routing and Its Functional Necessity The Advanced High-performance Bus (AHB) is a critical component in many ARM-based systems, providing a high-speed communication pathway between masters and subordinates (slaves). One of the key signals in the AHB protocol is HREADY, which plays a pivotal role in managing data transfer timing and synchronization….
MPAMF_BASE Address Configuration Challenges in ARM Systems The Memory Partitioning and Monitoring (MPAM) architecture extension is a critical feature in modern ARM systems, particularly for resource management and performance optimization in multi-core environments. However, one of the most common challenges developers face is correctly configuring and accessing the MPAM memory-mapped registers, specifically the MPAMF_BASE address….
MCU vs. MPU: Core Definitions and Functional Roles The terms MCU (Microcontroller Unit) and MPU (Memory Protection Unit) are often used interchangeably in discussions about ARM architectures, but they refer to fundamentally different components with distinct roles in embedded systems. An MCU is a complete computing system on a chip, integrating a processor core, memory,…
ARM Cortex-A53 AXI4 Narrower Transactions and Data Corruption The issue at hand involves data corruption during narrower transactions (32-bit writes) on an AXI4 bus when interfacing between an ARM Cortex-A53 processor and an AXI4-Lite IP. Specifically, when writing to the upper 32 bits of a 64-bit register (e.g., address 0x1004), the lower 32 bits (e.g.,…
DTCM Memory Access Bus Errors During Stack Relocation When attempting to relocate the stack from SRAM to DTCM (Data Tightly Coupled Memory) on an ARM Cortex-M7 microcontroller, such as the CYT4BFX, developers often encounter bus errors. These errors typically manifest as hard faults or access violations, preventing the system from functioning correctly. The root cause…
ARM Cortex-A15 Chromebook Linux Kernel Build Failures During QEMU/KVM Integration The Samsung XE303C12-A01US Chromebook, powered by the ARM Cortex-A15 processor, presents a unique challenge when attempting to build and run a custom Linux kernel with QEMU/KVM virtualization support. The primary issue revolves around kernel compilation errors, specifically related to the cpsid i and cpsie i…
ARM Cortex-M7 High CPU Load Despite Higher Clock Speed The ARM Cortex-M7 microcontroller, specifically the CYT4BFBCJE model running at 160 MHz, is exhibiting a significantly higher CPU load (95%) compared to an ARM Cortex-M4-based system (CYT2B9X) running at 80 MHz, which only experiences a 25% CPU load. Both systems are running identical vector BSW (Basic…
Understanding Cortex-A72 Prefetchers and Their Impact on Performance The Cortex-A72 processor, a high-performance ARM core, employs sophisticated prefetching mechanisms to optimize memory access patterns and improve overall system performance. These prefetchers, which include both L1 and L2 cache prefetchers, predict future memory accesses based on historical patterns and preload data into the cache to reduce…