ARM Cortex-A53 PMU Access Across Cores: Understanding the Challenge The Performance Monitoring Unit (PMU) in ARM Cortex-A53 processors is a critical component for profiling and optimizing system performance. Each core in a multi-core Cortex-A53 system has its own PMU, which can be accessed using the MRS and MSR instructions. However, a common challenge arises when…
ARM Trusted Firmware Interrupt Framework Limitations and Custom Handler Requirements The ARM Trusted Firmware (ATF) provides a robust framework for managing interrupts in secure and non-secure environments. However, one of the limitations of the ATF interrupt framework is the inability to directly register an interrupt handler with a specific interrupt ID. The framework reserves the…
NE10 Assembly File Syntax Errors with AARCH64 GCC Assembler The core issue revolves around the failure to build NE10 library assembly files for the ARM Cortex-A53 processor using the AARCH64 GCC assembler in a QNX 7.0.4 environment. The specific error occurs during the assembly phase, where the AARCH64 GCC assembler encounters an unrecognized character, the…
Understanding the Role of PORESETn, SYSRESETn, and DAPRESETn in Cortex-M3 Debugging The Cortex-M3 processor, as outlined in the Technical Reference Manual (TRM) r2p0 (Issue H), incorporates three distinct reset signals: PORESETn, SYSRESETn, and DAPRESETn. Each of these signals serves a unique purpose in the reset and debugging architecture of the processor. PORESETn, or Power-On Reset,…
BL2 at EL3 Execution Level and Custom BL33 Payload Integration Challenges The integration of BL2 at EL3 execution level with custom BL33 payloads in ARM Trusted Firmware-A (TF-A) presents a unique set of challenges, particularly when dealing with the i.MX8QM platform. The primary issue revolves around the proper configuration and utilization of the BL2_AT_EL3 build…
ARM Cortex-M4 Interrupt Vector Table Misalignment and Default Handler Execution When working with ARM Cortex-M microcontrollers, one of the most critical components of the system initialization process is the correct configuration of the interrupt vector table. The vector table is a memory region that contains the addresses of exception handlers, including interrupt service routines (ISRs)….
Cortex-M3 SysTick Timer Misconfiguration Leading to Incorrect Clock Ticks The issue at hand involves a Cortex-M3 bare-metal startup example where the reported clock ticks for various sorting algorithms (Insertion Sort, Shell Sort, and Quick Sort) are significantly lower than expected. The debug output shows values such as "Insertion sort took 1 clock ticks" and "Shell…
Memory Types in AXI4 Protocol and Their Role in Cache Coherency The AXI4 protocol, a cornerstone of modern ARM-based systems, defines several memory types through the AxCACHE signals. These memory types are critical in determining how memory transactions are handled, particularly in systems with caches and coherency protocols like ACE (AXI Coherency Extensions). The AxCACHE…
ARM Cortex-A77 Branch Prediction Challenges in 32-Byte Aligned Instruction Memory The ARM Cortex-A77 is a high-performance processor core designed for advanced applications, leveraging sophisticated branch prediction mechanisms to maximize instruction throughput. However, the performance of the Cortex-A77 can be significantly influenced by the placement and behavior of branch instructions within 32-byte aligned memory regions. This…
Secure Generic Timer Access Restrictions in Non-Secure EL1 The ARM Cortex-A53 processor, part of the ARMv8-A architecture, incorporates a generic timer that is essential for timekeeping and synchronization in embedded systems. This timer is typically implemented as a secure peripheral, meaning it is accessible only from secure exception levels (EL3 or Secure EL1/EL2). When running…