Author: System on Chips

Exception Handling Timing and Instruction Interruptibility in ARMv7-M The ARMv7-M architecture, widely used in Cortex-M series processors, implements a sophisticated exception handling mechanism that is critical for real-time embedded systems. A key aspect of this mechanism is determining when exceptions are taken into account relative to the instruction flow. Exceptions in ARMv7-M can be either…

ARM DynamIQ Cluster Fabric Topology Overview The ARM DynamIQ cluster represents a significant evolution in ARM’s multi-core processor architecture, particularly in how cores communicate and share resources. At the heart of this architecture lies the fabric topology, which determines the efficiency and scalability of data transfer between cores, caches, and other system components. The fabric…

ARM Cortex-M23 Interrupt Target Configuration and HardFault During Secure-to-Non-Secure Transition The ARM Cortex-M23 processor, with its TrustZone security extension, introduces a robust mechanism for separating secure and non-secure worlds. However, this separation adds complexity to interrupt handling, especially when transitioning interrupts from the secure world to the non-secure world. A common issue arises when configuring…

Non-Secure Callable (NSC) Functions in ARM TrustZone: Bridging Secure and Non-Secure Worlds The ARM TrustZone technology provides a robust security framework for embedded systems by partitioning the system into secure and non-secure worlds. This partitioning ensures that sensitive code and data are isolated from non-secure applications, thereby protecting critical system resources from unauthorized access. However,…

ARM Cortex-M7 Peak MIPS and Real-World Performance Discrepancies The ARM Cortex-M7 is a high-performance microcontroller core designed for embedded applications requiring significant computational power. One of the key metrics often used to evaluate the performance of such processors is MIPS (Million Instructions Per Second). However, calculating MIPS for the Cortex-M7 is not straightforward due to…

ARM Cortex-A53 TLB Coherency Issues During Block-to-Table Demotion In ARMv8-A architectures, particularly when dealing with AArch64, the Translation Lookaside Buffer (TLB) plays a critical role in managing virtual-to-physical address translations. One of the more nuanced challenges arises when transitioning from a block mapping to a table mapping, especially in a multi-processing element (PE) environment. This…

ARM Cortex-A9 Power Measurement Challenges with PAPI The ARM Cortex-A9 processor, part of the ARMv7-A architecture, is widely used in embedded systems for its balance of performance and power efficiency. However, measuring power consumption on such processors, especially when running cryptographic algorithms or other compute-intensive tasks, can be challenging. The Performance Application Programming Interface (PAPI)…

ARM Cortex-A9 Cache Write-Back Granule and STR Instruction Impact The ARMv7-A architecture, particularly when implemented in processors like the Cortex-A9, introduces nuanced behaviors when executing store instructions such as STR. The STR r1, [r0] instruction writes the contents of register r1 to the memory address specified by register r0. However, the interaction between this instruction…

ARMv8.2-A Architecture: Mandatory Features and Optional Extensions The ARMv8.2-A architecture is an extension of the ARMv8-A architecture, introducing several mandatory features and optional extensions that enhance the capabilities of ARM processors. A full implementation of ARMv8.2-A requires compliance with both the mandatory architectural features and any additional requirements specified in the ARM Architecture Reference Manual….

SError Interrupt Handling and Exception Level Confusion The ARM architecture defines SError (System Error) interrupts as asynchronous aborts that can occur due to various hardware faults, such as memory system errors or incorrect device register accesses. These interrupts are critical for system reliability, but their asynchronous nature complicates determining the exact Exception Level (EL) where…