Architectures and Processors

ARM Cortex-A53 CPSR Corruption After Exception Return from EL3 to EL1 The ARM Cortex-A53 processor, part of the ARMv8-A architecture, is designed to handle exceptions and interrupts across multiple exception levels (ELs). A critical issue arises when returning from an exception in EL3 (Secure Monitor) to EL1 (OS Kernel), where the CPSR (Current Program Status…

ARM Cortex-R4 Interrupt Handling Failure with VIC and ICUA Integration The ARM Cortex-R4 is a high-performance processor designed for real-time applications, often integrated with complex interrupt controllers like the Vector Interrupt Controller (VIC) and ICUA (Interrupt Control Unit A) in systems such as Renesas Electronics’ RZ/T1. In this scenario, the Cortex-R4 fails to handle interrupts…

Cortex-M0+ SWD Debug Protocol Implementation Challenges Developing a Serial Wire Debug (SWD) debugger for the ARM Cortex-M0+ processor, particularly when targeting an FPGA-based implementation, presents several technical challenges. The SWD protocol, while relatively simple in its basic form, requires a deep understanding of the ARM Debug Interface Architecture and the Cortex-M0+ core’s debug capabilities. The…

ARM Cortex-R52 Interrupt Vector Offset Configuration Challenges The ARM Cortex-R52, a real-time processor designed for safety-critical applications, presents unique challenges when configuring the interrupt vector table offset. Unlike the Cortex-M series, which utilizes the Vector Table Offset Register (VTOR) for straightforward interrupt vector table relocation, the Cortex-R52 employs a different mechanism due to its more…

ARM Cortex-M7 ITCMERR Signal Protocol and CPU Behavior The ITCMERR signal in the ARM Cortex-M7 processor is a critical part of the Instruction Tightly Coupled Memory (ITCM) protocol, which is used to indicate errors during instruction fetches from the ITCM. When the ITCMERR signal is set HIGH, the CPU must handle the error condition in…

ARM Cortex-A IERRR Bit Set Persistently Before and After GIC Initialization The IERRR (Internal Error Reporting Register) bit being set persistently before and after Generic Interrupt Controller (GIC) initialization on an ARM Cortex-A processor is a critical issue that can indicate underlying hardware or software problems. The IERRR bit is part of the processor’s error…

EL2 Memory Corruption During Secure to Non-Secure Memory Access The core issue revolves around memory corruption observed when attempting to read a memory block at address 0x80280000 from Exception Level 2 (EL2) after the memory was initially configured and loaded by a bootloader running at Exception Level 3 (EL3). The memory corruption manifests as random…

ARM Cortex-A Hypervisor Timer Interrupt Configuration and Debugging When working with ARM Cortex-A processors in a hypervisor environment, configuring and debugging timer interrupts can be a complex task, especially when dealing with Exception Levels (ELs) and the Generic Interrupt Controller (GIC). The issue at hand involves a hypervisor running in EL2 (AArch64) attempting to use…

ARM Cortex-M0 Bootloader to Application Jump Mechanics The process of transitioning from a bootloader to an application on an ARM Cortex-M0 processor, such as the XMC1302, involves several critical steps that must be meticulously handled to ensure a smooth and reliable jump. The Cortex-M0, being a Thumb-only processor, executes instructions in Thumb mode, which inherently…

GIC Interrupt Configuration Mismatch Between IP and GIC Registers The core issue revolves around the configuration of the ARM Generic Interrupt Controller (GIC) to handle interrupts generated by an Intellectual Property (IP) block. Specifically, the IP generates edge-triggered interrupts, but there is a question of whether the GIC can be programmed to handle these interrupts…