kernel

Kernel modules for Linux, macOS, Windows

This directory contains the kernel modules for Linux, macOS, Windows, in their respective subdirectories. In all cases, the name of the module is cpusysregs.

The header file cpusysregs.h defines the interface between the kernel module and the userland. This file is included in the sources of the kernel modules (Linux, macOS, Windows) and in the applications.

Due to the architectures of the kernel modules interfaces in the various OS, the details of the interfaces are slightly different.

• On Linux, the kernel module creates a special device named /dev/cpusysregs. Accessing the CPU system registers is done using ioctl() on this device.
• On macOS, the kernel extension uses the system socket communication. It defines a system socket named cpusysregs. Accessing the CPU system registers is done using getsockopt() and setsockopt() on this socket.
• On Windows, the kernel driver creates a special device named \\.\cpusysregs. Accessing the CPU system registers is done using DeviceIoControl() on this device.

In the apps directory, the C++ class named RegAccess (files regaccess.h and .cpp) encapsulates these differences to provide a higher-level of abstraction.

The script ../aarch/extract-sreg-definitions.sh automatically generates the CSR_SREG_xxx definitions of all Arm system registers, as used in cpusysregs.h. The definition of all registers is based on reference XML files on the Arm public web site. This script may be executed each time an update of the Arm architecture is published.