ARM CHI Protocol Snoop Transactions and Their Role in Coherency The ARM Coherent Hub Interface (CHI) protocol is a critical component in modern ARM-based SoCs, enabling efficient communication between various request nodes (RNs) and the interconnect. One of the key aspects of CHI is its handling of snoop transactions, which are essential for maintaining cache…
ARMv9 RME Support in Fast Models FVP: Missing Configuration Parameters The Realm Management Extension (RME) is a critical feature introduced in ARMv9 architectures, designed to enhance security by providing hardware-enforced isolation between different execution environments, such as Normal, Secure, and Realm worlds. Fast Models Fixed Virtual Platforms (FVPs) are widely used for pre-silicon development and…
Master AHB Lite to AHB5 Slave Connectivity and Addressing Misalignment The core issue revolves around the integration of a Master AHB Lite interface with an AHB5 Slave, specifically when attempting to bridge AHB5 to AXI5 for FPGA testing. The primary challenge lies in the misalignment of address spaces between the MicroBlaze processor and the AHB5_AXI5…
CHI Device Memory Type Byte Access Behavior and Boundary Crossing In ARM’s Coherent Hub Interface (CHI) protocol, the handling of "Device" memory type transactions presents unique challenges, particularly when the transaction size exceeds the natural alignment boundary of the address space. Unlike "Normal" memory type transactions, which can wrap around address boundaries seamlessly, "Device" memory…
Inaccurate Timing Measurements with ARM Cortex-M4 DWT_CYCCNT on FVP When benchmarking code on the FVP_MPS2_Cortex-M4 simulator, one of the primary challenges is obtaining accurate timing measurements. The ARM Cortex-M4 processor provides a Data Watchpoint and Trace (DWT) unit, which includes a cycle counter (DWT_CYCCNT) that can be used to measure the number of clock cycles…
ARM Foundation Platform’s Pointer Authentication Algorithm Configuration The ARM Foundation Platform is a critical tool for developers and verification engineers working on ARM-based SoCs. It provides a reference environment for testing and validating ARM architectures, including advanced features like pointer authentication. Pointer authentication is a security feature introduced in ARMv8.3-A, designed to mitigate return-oriented programming…
ARM AArch64 Linux Emulation on x86-64 Host via QEMU Emulating an ARM AArch64 Linux environment on an x86-64 host machine presents a unique set of challenges, particularly when the goal is to test userspace applications. The primary tool for this task is QEMU, a versatile emulator that supports both user-mode and system-level emulation. However, the…
ARM Mali C71AE Performance Counters: Absence of Thread-Level Metrics The ARM Mali C71AE Image Signal Processor (ISP) is a highly optimized IP block designed for real-time image processing, capable of delivering one pixel per clock cycle under ideal conditions. However, when integrating the Mali C71AE into a larger SoC, particularly within a video processing subsystem,…
ARM ACE Protocol Snoop Channel Design Rationale and ID Omission The ARM ACE (AXI Coherency Extensions) protocol is designed to facilitate cache coherency in multi-master systems, ensuring that all masters observe a consistent view of memory. A critical aspect of this protocol is the snoop channel, which is responsible for managing coherency transactions between masters…
ARM FVP Realm Creation and Entry Feasibility The concept of Realms within ARM’s Fixed Virtual Platforms (FVP) is a critical aspect of modern ARM-based system-on-chip (SoC) design, particularly when dealing with secure environments and virtualization. Realms are isolated execution environments that provide a secure space for running trusted applications, separate from the normal world and…