CMSIS-Core (Cortex-A) implements the basic run-time system for a Cortex-A device and gives the user access to the processor core and the device peripherals. In detail it defines:

Hardware Abstraction Layer (HAL) for Cortex-A processor registers with standardized definitions for the GIC, FPU, MMU, Cache, and core access functions.
System exception names to interface to system exceptions without having compatibility issues.
Methods to organize header files that makes it easy to learn new Cortex-A microcontroller products and improve software portability. This includes naming conventions for device-specific interrupts.
Methods for system initialization to be used by each MCU vendor. For example, the standardized SystemInit() function is essential for configuring the clock system of the device.
Intrinsic functions used to generate CPU instructions that are not supported by standard C functions.
A variable to determine the system clock frequency which simplifies the setup of the system timers.

The following sections provide details about the CMSIS-Core (Cortex-A):

Using CMSIS in Embedded Applications describes the project setup and shows a simple program example.
CMSIS-Core Device Templates describes the files of the CMSIS-Core (Cortex-A) in detail and explains how to adapt template files provided by Arm to silicon vendor devices.
MISRA-C Deviations describes the violations to the MISRA standard.
API Reference describes the features and functions of the Device Header File <Device.h> in detail.
Data Structures describe the data structures of the Device Header File <Device.h> in detail.

Access to CMSIS-Core (Cortex-A)

CMSIS-Core is actively maintained in CMSIS 6 GitHub repository and released as part of the CMSIS Software Pack.

The following directories and files relevant to CMSIS-Core (Cortex-A) are present in the ARM::CMSIS Pack:

Directory	Content
📂 CMSIS	CMSIS Base software components folder
┣ 📂 Documentation/html/Core_A	A local copy of this CMSIS-Core (A) documentation
┗ 📂 Core	CMSIS-Core files
┣ 📂 Include	CMSIS-Core Processor Files.
┗ 📂 a-profile	Header files specific for Arm A-Profile.
┗ 📂 Template	Template Files

Processor Support

CMSIS supports a selected subset of Cortex-A processors.

Cortex-A Technical Reference Manuals

The following Technical Reference Manuals describe the various Arm Cortex-A processors:

Cortex-A5 (Armv7-A architecture)
Cortex-A7 (Armv7-A architecture)
Cortex-A9 (Armv7-A architecture)

Tested and Verified Toolchains

The CMSIS-Core Device Templates supplied by Arm have been tested and verified with the following toolchains:

Arm: Arm Compiler 5.06 update 7
Arm: Arm Compiler 6.16
Arm: Arm Compiler 6.6.4
GNU: GNU Arm Embedded Toolchain 10-2020-q4-major (10.2.1 20201103)
IAR: IAR ANSI C/C++ Compiler for Arm 8.20.1.14183