ARM SMMU and GPT Interaction in Realm Memory Access Scenarios The ARM System Memory Management Unit (SMMU) plays a critical role in managing memory access permissions for devices in a system. When combined with the Granule Protection Table (GPT) in ARM’s Confidential Compute Architecture (CCA), the SMMU ensures that devices adhere to strict memory access…
ARM Cortex-M0 and Cortex-M3 Instruction Set Differences and Their Impact on C Code Performance The ARM Cortex-M0 and Cortex-M3 microcontrollers are both popular choices for embedded systems, but they differ significantly in their instruction sets and capabilities. The Cortex-M0 is designed for ultra-low-power and cost-sensitive applications, featuring a reduced instruction set that is a subset…
PSEL and PENABLE Signal Timing and Protocol Compliance in APB Transfers The Advanced Peripheral Bus (APB) protocol is a critical component of the AMBA (Advanced Microcontroller Bus Architecture) family, widely used in ARM-based systems for low-bandwidth, low-power peripheral communications. The PSEL (Peripheral Select) and PENABLE (Peripheral Enable) signals are fundamental to the APB protocol, governing…
ARMv8 Foundation Platform Emulation Failure with Linux Boot and Terminal Access Issues The ARMv8 Foundation Platform (FP) is a widely used emulation environment for testing and developing software targeting ARM architectures. It provides a virtualized hardware environment that emulates ARMv8-A processors, enabling developers to run operating systems like Linux without requiring physical hardware. However, a…
STM32F030K6T6TR Initial Programming Success and Subsequent Failures The STM32F030K6T6TR microcontroller, a member of the STM32F0 series based on the ARM Cortex-M0 core, is a popular choice for low-power and cost-sensitive embedded applications. The issue at hand involves the successful initial programming of the STM32F030K6T6TR using the STM32Programmer tool via a NUCLEO-64 STM32F411RE board acting as…
ARM Cortex-R52 PMU Cycle Counter Configuration and Initialization Issues The ARM Cortex-R52 processor includes a Performance Monitoring Unit (PMU) that provides performance counters, including a cycle counter (CCNT), to measure and analyze system performance. The cycle counter is a critical tool for profiling and understanding the timing behavior of software running on the Cortex-R52. However,…
ARM PE Access to Peripherals and Memory-Mapped Devices In ARM-based systems, the Processing Element (PE) accesses peripherals and memory-mapped devices through a combination of memory-mapped I/O (MMIO) and system interconnects. The PE uses load (LDR) and store (STR) instructions to interact with peripheral registers and memory regions, treating them as if they were regular memory…
ARMv7M Instruction Encoding Ambiguity Between B.W and DSB In the ARMv7-M architecture, the encoding of certain instructions can lead to ambiguity when interpreting machine code. Specifically, the B<c>.W (Branch with condition, wide) and DSB (Data Synchronization Barrier) instructions share overlapping encoding patterns under specific conditions. This overlap arises due to the way the instruction set…
ARM Cortex-A Memory Attribute Indirection Register (MAIR) Misconfiguration in Linux Kernel 5.10+ The issue revolves around a misconfiguration in the Memory Attribute Indirection Register (MAIR) in ARM Cortex-A processors when using Linux kernel versions 5.10 and above. This misconfiguration manifests as alignment issues during memory access operations such as memset() and memcpy() on mmap’ed memory…
SWD Protocol Initialization and Deprecated Sequence Observation The SWD (Serial Wire Debug) protocol is a two-pin interface used for debugging ARM Cortex-M microcontrollers, including the STM32F103. During the initialization phase of the SWD protocol, the debugger (in this case, JLink EDU) communicates with the target device to establish a connection. This process involves several distinct…