Author: System on Chips

Cortex-A9 Multi-Core Boot Sequence and Cache Coherency Challenges The Cortex-A9 processor, particularly in its multi-core (MP) configuration, presents unique challenges during the boot sequence, especially when dealing with cache initialization and coherency across multiple cores. The primary concern revolves around the timing and sequence of enabling the L2 cache (L2C-310) in a multi-core environment. The…

ARM Cortex-A53 Alignment Faults During Single Float Load Operations When working with the ARM Cortex-A53 processor, a common issue arises when the compiler generates ldr q0, [x1, #0] instructions for single float load operations, such as scratch_in[0] = Fin_r[0 * in_step];. This instruction attempts to load a 128-bit value into the Q register (Q0) from…

ARM FVP DRAM Size Configuration Failure When working with ARM Fixed Virtual Platforms (FVPs), one of the critical tasks is configuring the total compute DRAM size to match the requirements of the target application or system. A common issue arises when attempting to set the DRAM size using the -C board.dram_size parameter, only to find…

Write Data Storage Mechanisms in AXI Protocol During Outstanding Transactions The Advanced eXtensible Interface (AXI) protocol, widely used in ARM-based systems, is designed to handle high-performance data transfers between masters and slaves. One of the key features of AXI is its ability to support outstanding transactions, where data can be sent before the corresponding address….

AXI Protocol Peripheral Attribute Execution Order Ambiguity The Advanced eXtensible Interface (AXI) protocol is a widely adopted on-chip communication standard for high-performance embedded systems, particularly in ARM-based architectures. One of the critical aspects of the AXI protocol is its handling of transaction ordering, which ensures data consistency and predictable behavior across different system components. However,…

Misaligned Byte Transfers on Word-Addressable APB Slaves The core issue revolves around the behavior of an AHB2APB bridge when handling narrow byte transfers, specifically when the AHB master initiates a single-byte read transaction targeting a word-addressable APB slave. The AHB master sends a starting address of 0x01 with HSIZE set to 0 (indicating a byte…

ARM Cortex-A55 and GIC-600: SPI Interrupt Distribution Challenges in AMP Systems In systems utilizing the ARM Cortex-A55 cores alongside the GIC-600 interrupt controller, a common challenge arises when attempting to distribute a single Shared Peripheral Interrupt (SPI) to multiple Processing Elements (PEs) concurrently. This scenario is particularly relevant in Asymmetric Multiprocessing (AMP) systems, where one…

ARM Cortex Cache Indexing Mechanism and Physical Address Discrepancy In ARM architectures, particularly in ARMv8-A and ARMv9-A, the relationship between Physical Addresses (PA) and cache set numbers is a nuanced topic that often leads to confusion. The cache indexing mechanism is designed to optimize memory access patterns, reduce contention, and improve overall system performance. However,…

Understanding R5F Lockstep Mismatch Errors in Versal PLM The Versal VCK190 and VMK180 platforms utilize the ARM Cortex-R5F processor in lockstep configuration to enhance fault tolerance and reliability in safety-critical applications. Lockstep mode involves running two identical Cortex-R5F cores in parallel, with their outputs compared in real-time to detect discrepancies. When a mismatch occurs, it…

Exclusive Access Mechanisms in AXI3 and AXI4: A Comparative Analysis Exclusive access is a critical feature in ARM’s AXI (Advanced eXtensible Interface) protocol, designed to support atomic operations in multi-master systems. It allows a master to perform a read-modify-write sequence without interference from other masters, ensuring data integrity. In AXI3, exclusive access is defined as…