Understanding AXI-5 User Loopback Signaling in ARM Architectures The AXI-5 protocol, an evolution of the Advanced eXtensible Interface (AXI) specification, introduces several enhancements to improve performance, scalability, and flexibility in ARM-based systems. One of the notable additions is the User Loopback Signaling mechanism, which includes signals such as AWLOOP, BLOOP, ARLOOP, and RLOOP. These signals…
Cortex-A53 Debugger Disconnection During Hypervisor Boot at EL2 The core issue revolves around the loss of debugger control when booting a Cortex-A53 core on an S32G2 platform using a custom Type 1 Hypervisor. The hypervisor runs at Exception Level 2 (EL2) and is initialized by a Cortex-M7 core. While the system operates correctly when booted…
ARM SVE Intrinsic Definitions Obfuscated by GCC Pragmas The ARM Scalable Vector Extension (SVE) is a powerful feature for high-performance computing, enabling vectorized operations on ARM architectures. Developers often rely on intrinsic functions provided in the arm_sve.h header file to leverage SVE capabilities. However, the implementation of arm_sve.h in GCC (specifically the aarch64-linux-gnu v14 compiler)…
ARM Cortex-A9 Cache Behavior During Secondary Core Initialization In ARM Cortex-A9 multi-core systems, cache initialization and management are critical for ensuring correct and efficient execution of code, especially in environments where each core runs its own instance of a Real-Time Operating System (RTOS). The Cortex-A9 processor features a unified L1 cache and an optional L2…
ARM Neoverse N2 SVE Vector Length Configuration Mismatch at EL0 The ARM Neoverse N2 processor, a high-performance core designed for infrastructure and cloud workloads, implements the Scalable Vector Extension (SVE) as part of its architecture. SVE allows for variable vector lengths, which can be configured through system registers such as ZCR_EL3, ZCR_EL2, and ZCR_EL1. However,…
TCMRETRY Signal and ECC Error Detection in ARMv7 TCMs The TCMRETRY signal in ARMv7 processors is a critical component for handling Error Correction Code (ECC) errors in Tightly Coupled Memories (TCMs). TCMs are high-speed memory blocks closely integrated with the processor core, providing low-latency access for critical data and instructions. When ECC is implemented in…
ARM Cortex-A53 Core Shutdown During AT S12E1R Instruction Execution The ARM Cortex-A53 processor is a widely used 64-bit core in embedded systems, known for its efficiency and performance. However, when implementing a bare-metal hypervisor, developers may encounter a critical issue where the core shuts down or becomes unresponsive during the execution of the AT S12E1R…
PHP 5.6 and Xalan: Criticality in Corstone-201 RTL Generation The generation of the top-level RTL for the Corstone-201 subsystem is a complex process that relies on a variety of tools and dependencies. Among these, PHP 5.6 and Xalan have been identified as potential bottlenecks due to installation challenges on RHEL 8.4. PHP 5.6 is a…
DMA330 Microcode Limitations for Linked-List DMA Transfers The DMA330, also known as the PL330, is a highly configurable DMA controller widely used in ARM-based systems. It is designed to handle complex data transfer tasks with minimal CPU intervention. However, programming the DMA330 to perform linked-list-style DMA transfers, particularly for circular buffer implementations, presents unique challenges…
SWD Communication Random Read Values Under High Hardware Memory Contention When using Serial Wire Debug (SWD) to read memory locations that are also heavily accessed by hardware, a common issue arises where the SWD interface occasionally returns random or incorrect values. This problem is particularly pronounced in systems where hardware (HW) memory access is given…