Author: System on Chips

ARMv8 Virtualization and Address Translation Challenges in Mixed Environments In ARMv8-based systems, virtualization is a critical feature that enables the coexistence of virtual machines (VMs) and native applications within the same hardware environment. The ARMv8 architecture provides a two-stage address translation mechanism: Stage 1 (S1) translation, which is managed by the guest operating system (OS)…

ARM Cortex-M55 System Counter and System Timer Register Map Accessibility The ARM Cortex-M55 processor incorporates a sophisticated System Counter and System Timer, which are critical for real-time operations and system synchronization. The System Counter provides a continuous timebase, while the System Timer generates periodic interrupts based on this timebase. These components are essential for tasks…

ROM Firmware Code Coverage Challenges in RTL Simulation When working with ARM Cortex-M0/M0+ processors, ensuring comprehensive ROM firmware code coverage during the RTL (Register Transfer Level) simulation phase is critical for validating the correctness and robustness of embedded systems. ROM firmware, being non-volatile and often critical to system boot-up and operation, must be thoroughly tested…

ARMv7 PMU Event Counter Configuration and Initialization Issues The ARMv7 Performance Monitoring Unit (PMU) is a powerful tool for profiling and analyzing system performance, particularly in embedded systems. However, a common issue arises when the event counters consistently return zero, while the cycle counter functions as expected. This problem often stems from improper configuration or…

ARM Cortex-A55 Program Hangs During Execution with Large Program Size The issue at hand involves a Cortex-A55-based bare-metal debugging scenario where the program hangs during execution when the program size exceeds a certain threshold. The problem manifests specifically when attempting to branch to a function (access_test2()), which results in an undefined branch destination. This behavior…

ARM Cortex CPU Cycle Counting Mechanisms: CPU_CYCLES and PMCCNTR_EL0 The ARM architecture provides two distinct mechanisms for counting CPU cycles: the CPU_CYCLES Performance Monitoring Unit (PMU) event and the dedicated cycle counter register PMCCNTR_EL0. While both mechanisms aim to measure CPU cycles, they serve different purposes and operate under different constraints. The CPU_CYCLES event is…

ARM Cortex-M23 Timing Constraints and Clock Gating Challenges in FPGA Synthesis When implementing an ARM Cortex-M23 core on an FPGA platform such as the Xilinx VCU118 board, meeting timing constraints at higher clock frequencies can be a significant challenge. The Cortex-M23, being a low-power, area-optimized processor, is designed for embedded applications where power efficiency and…

GIC Memory Map Misconfiguration Leading to System Hangs In bare-metal ARM development, particularly when working with ARM Cortex-A55 and Cortex-A75 cores, the configuration of the Generic Interrupt Controller (GIC) memory map is critical for proper system operation. The GIC is responsible for managing interrupts, and its memory map must be correctly set up to ensure…

ICH_EISR_EL2 Register and Its Role in Handling Multiple EOIs The ICH_EISR_EL2 (Interrupt Controller Hyp End of Interrupt Status Register) is a critical component in the ARM Generic Interrupt Controller (GIC) architecture, specifically within the GICv3 virtualization extensions. This register is designed to report the status of End of Interrupt (EOI) operations for virtual interrupts handled…

ARM Cortex-A72 DAIF Register Operation Overhead The ARM Cortex-A72 processor, part of the ARMv8-A architecture, exhibits significantly higher latency when performing operations on the DAIF (Debug, Abort, Interrupt, and Fast interrupt) register compared to the Cortex-A53. The DAIF register is critical for managing interrupt handling and system state, and its operations are fundamental to low-level…