exectos/xtoskrnl

XTOSKRNL

XTOSKRNL is an XT system kernel executable, providing the kernel and executive layers for XTOS kernel space. It is a fundamental part of ExectOS, responsible for various core services like hardware abstraction or memory management. This kernel, contains the scheduler (called sometimes as Dispatcher), cache, object and memory managers, security manager and other kernel executives described below.

All routines in kernel are prefixed to indicate the kernel subsystem they belong and put inside separate directory. This is a list of them:

• Ar - Architecture library
• Ex - Kernel Executive
• Hl - Hardware Abstraction Layer (HAL)
• Ke - Core kernel library
• Mm - Memory manager
• Po - Plug&Play and Power Manager
• Rtl - Runtime library

AR: Architecture Library

This module contains processor architecture specific functions. This includes enabling and disabling interrupts at the processor, getting the address of a page fault, getting CPUID information, and performing very early processor initialization. This module does not contain any manufacturer or board-specific code, only CPU architecture specific code.

EX: Kernel Executive

The kernel executive supplies heap management, including support for allocating system memory from paged/non-paged pools, as well as synchronization primitives like push locks and fast mutexes, interlocked memory access, and worker threads.

HL: Hardware Abstraction Layer

Hardware Abstraction Layer (HAL), is a layer between the physical hardware of the computer and the rest of the operating system. It was designed to hide differences in hardware and therefore it provides a consistent platform on which the system and applications may run.

KE: Kernel Library

The kernel implements its core functionality that everything else in the system depends upon. This includes basic low-level operations such as routing hardware interrupts.

MM: Memory Manager

Memory Manager is one of core subsystems. It manages virtual memory, controls memory protection and the paging of memory in and out of physical memory to secondary storage. It also implements a general-purpose allocator of physical memory.

PO: Plug&Play and Power Manager

This subsystem deals with power events, such as power-off, stand-by, or hibernate. It also handles Plug&Play and supports device detection and installation at boot time. It is responsible for starting and stopping devices on demand.

RTL: Runtime Library

This is a required static copy of C runtime objects. It includes many utility functions that can be used by native applications.

Functions Naming Convention

When naming a kernel functions, certain conventions are used. The function name is usually structured with <Prefix><Operation><Object>. The prefix denotes the module to which it belongs, thus module can be identified simply by the name of the function. Additionally, the prefix identifies the function visibility as well. Thus all private functions, that should not be used from outside of the module has added "p" suffix to the prefix. For example, KepInitializeStack() routine:

• Kep - prefix meaning this is private routine belonging to Kernel library (Ke) module,
• Initialize - operation this function does with the object,
• Stack - the object is stack.