Architectures and Processors

ARM Cortex-M MVE and Cortex-A Neon Intrinsics: Functional Overlap and Divergence The ARM Cortex-M series, particularly those supporting the M-profile Vector Extension (MVE), and the Cortex-A series, which leverages Advanced SIMD (Neon) intrinsics, are both designed to accelerate vectorized operations in embedded systems. However, their architectural goals, use cases, and implementation details differ significantly, despite…

ARM Corstone SSE-700 MHU v2.1 R2NR Interrupt Trigger Mechanism The ARM Corstone SSE-700 subsystem integrates the Message Handling Unit (MHU) v2.1, a critical component for inter-processor communication (IPC) via mailbox mechanisms. The MHU v2.1 supports multiple interrupt types, including the Receiver-to-Non-Receiver (R2NR) interrupt. The R2NR interrupt is triggered when the ACC_RDY signal transitions from HIGH…

External SRAM Burst Waveform Errors with Cacheable Memory and Disabled Data Cache The core issue revolves around accessing external SRAM regions marked as cacheable in the MMU page tables while the data cache is disabled. This configuration leads to errors in the burst waveform during memory access. The system in question has the MMU enabled,…

ARM Cortex-A Virtual IRQ and IRQ Routing in EL2 and EL1 The ARM architecture, particularly when virtualization is involved, introduces complexities in interrupt handling that can be challenging to understand, especially for those new to ARM virtualization. The core issue revolves around how physical interrupts (IRQs) and virtual interrupts (vIRQs) are routed and handled in…

Cortex-A76 MMU Translation Table Initialization and EL2 to EL1 Transition Issues The core issue revolves around the failure to initialize the Memory Management Unit (MMU) translation tables correctly on an ARM Cortex-A76 processor during the boot process of a bare metal kernel. The problem manifests when the kernel attempts to transition from Exception Level 2…

ARM Cortex-A7 TrustZone Architecture and Documentation Gaps The ARM Cortex-A7 processor, part of the ARMv7-A architecture, incorporates ARM TrustZone technology to provide a secure execution environment. TrustZone divides the system into Secure and Non-Secure worlds, allowing sensitive operations to be isolated from the rest of the system. However, implementing TrustZone on the Cortex-A7 can be…

ARM Cortex-A GPT Information Caching in TLB: Architectural Implications The ARM Cortex-A architecture introduces a mechanism where Granule Protection Table (GPT) information can be cached within the Translation Lookaside Buffer (TLB). This architectural feature is designed to optimize performance and reduce area overhead in systems implementing Stage 1, Stage 2, and Granule Protection Check (GPC)…

ARM Cortex-A53 Cache Behavior in Uncacheable Memory Regions The ARM Cortex-A53 processor is a widely used 64-bit CPU core that implements the ARMv8-A architecture. One of its key features is the L1 data cache, which is designed to improve performance by reducing memory access latency. However, the behavior of the L1 data cache when interacting…

ARM Cortex-M55 AXI 64-bit Peripheral Write Access Issue: Splitting into Two 32-bit Transactions The ARM Cortex-M55 processor, while capable of generating 64-bit AXI transactions for normal memory, splits 64-bit write accesses to peripheral (device) memory into two separate 32-bit AXI transactions. This behavior is observed when using the STRD (Store Register Dual) instruction to write…

ARM Cortex-M33 HardFault_Handler Implementation Challenges The ARM Cortex-M33 processor, part of the ARMv8-M architecture, introduces several advanced features such as TrustZone security, enhanced DSP capabilities, and improved fault handling mechanisms. However, implementing a robust HardFault_Handler for the Cortex-M33 can be challenging, especially when the goal is to capture and dump core register contents during a…