ARM Cortex-R4/R5 PC Value Offset During Execution The Program Counter (PC) in ARM Cortex-R4 and Cortex-R5 processors exhibits a behavior where it points 8 bytes ahead of the current instruction being executed. This offset is not a bug or an anomaly but a deliberate architectural design choice rooted in the history of ARM processors and…
Variable Execution Time of UDIV Due to Early Termination Mechanism The ARM Cortex-M4 processor, like many modern microcontrollers, incorporates a hardware division unit that supports both signed (SDIV) and unsigned (UDIV) integer division. While this feature significantly accelerates division operations compared to software-based implementations, it introduces a critical challenge for developers requiring deterministic execution times….
ARMv8-A72 MMU Translation Error at Level 1 During Initialization When enabling the Memory Management Unit (MMU) on an ARMv8-A72 processor, a common issue that arises is a translation error at Level 1 of the page table hierarchy. This error typically occurs immediately after setting the MMU enable bit in the System Control Register (SCTLR_EL3). The…
ARM MMU-600 TBU and TCU Invalidation Message Scenarios The ARM MMU-600 (Memory Management Unit) is a critical component in modern ARM-based systems, particularly in high-performance computing and embedded systems where memory management and translation are paramount. The MMU-600 consists of two primary units: the Translation Buffer Unit (TBU) and the Translation Control Unit (TCU). Understanding…
ARM Pseudocode Arithmetic: Bitstring and Integer Operations in PC Relative Addressing The ARM architecture employs pseudocode to describe the behavior of instructions and operations in a human-readable yet precise manner. One such operation involves the subtraction of an integer from a bitstring, specifically in the context of Program Counter (PC) relative addressing. This operation is…
ARM Cortex-A78 DC ZVA Instruction Alignment Fault During Linux Kernel Boot DC ZVA Instruction Execution Failure in __pi_memset Function The ARM Cortex-A78 processor is encountering an alignment fault when executing the DC ZVA (Data Cache Zero by VA) instruction within the __pi_memset function during the Linux kernel boot process. The __pi_memset function is part of…
ARM Cortex-M33 IBUSERR Flag Generation and HardFault/BusFault Scenarios The IBUSERR flag, represented by bit 0 in the BusFault Status Register (BFSR), is a critical indicator of instruction bus errors on ARM Cortex-M33 processors. When the IBUSERR flag is set, it signifies that the processor has encountered a fault during an instruction fetch operation. This fault…
Cortex-R8 SMP Core 0 Stuck in WFE State After SEV Execution In a multi-core Cortex-R8 system, Core 0 enters a Wait For Event (WFE) state while waiting for a spinlock. Despite another core executing a Send Event (SEV) instruction, Core 0 fails to wake up and resume execution. This behavior indicates a breakdown in the…
ARM Cortex-A9 Vector Table Remapping and IRQ Handling Misalignment The ARM Cortex-A9 processor, like other ARMv7-A architecture processors, relies on a vector table to handle exceptions and interrupts. The vector table contains addresses of exception handlers, and its base address is stored in the Vector Base Address Register (VBAR). Properly remapping the vector table is…
GIC-600 ACE-Lite Slave Port and Its Role in Register Access The Generic Interrupt Controller 600 (GIC-600) is a critical component in ARM-based systems, responsible for managing interrupts across multiple processors and peripherals. One of the key architectural features of the GIC-600 is its ACE-Lite slave port, which is used for accessing its internal registers. The…