Software interrupts, or SVCs as they are now known, are generated by using the ARM instruction SVC. This causes an exception to be taken, and forces the processor into Supervisor mode, which is privileged. A user program can request services from an operating system through such exception handling mechanisms.1
In the AArch64 execution state, there are three privileged modes and one user mode. These are referred to as exception levels. The higher the exception level, the more privilege the code has.
The AArch64 processor provides two major modes of operation, referred to as execution states. They are 32-bit AArch32 state, and 64-bit AArch64 state.
In the A32 and T32 instruction sets, the Program Counter(PC) and Stack Pointer(SP) are general purpose registers. This is not the case in A64 instruction set.
As a general-purpose register in ARMv7, the PC introduced compiler complications and complex pipeline design.
Removing direct access to the PC in ARMv8 makes return prediction easier and simplifies the ABI specification.
ISO/IEC C++ standard basic types specification: Fundamental types, Compound types and CV-qualifiers.
The ISA is a contract between the hardware and the software. It defines the set of instructions and the set of registers that the hardware must support.
The most important components of the CPU are the registers, where data is stored, and the arithmetic and logic unit (ALU), where arithmetic and logical operations are performed on the data.
Arm® processors provide general-purpose and special-purpose registers. Some additional registers are available in privileged execution modes.
Registers which can be used freely are referred to as volatile, and registers which must be preserved or restored before returning are referred to as non-volatile.
How to compile/generate AArch32 code and run on an Linux/AArch64?
How to build AArch64-ELF for a popular embedded target board under Windows/x86_64 or macOS/arm64?
In computer science, a calling convention is an implementation-level (low-level) scheme for how subroutines or functions receive parameters from their caller and how they return a result.
ARM's original abbreviation was Acorn RISC Machine.
The cores and instruction sets used by ARM do not correspond one-to-one.
In November 1990, Acorn, Apple and VLSI jointly funded the creation of ARM. Acorn RISC Machine has also been officially renamed Advanced RISC Machine.
After ARM11, ARM processor cores no longer have the ARM prefix. But the word ARM has not disappeared from the Cortex series. The three major series of Cortex, M-R-A, together are ARM.