x86 32-bit Bare Metal Kernel

A hobby 32-bit x86 kernel developed in C and NASM assembly, with the goal of exploring low-level system programming, virtual memory/segmentation, interrupt handling and general OS functionalities

Technologies Used

• C
• x86 Assembly (NASM)
• GNU Toolchain
• QEMU
• GRUB & Multiboot specification

Key Features

Memory Management System

• Physical frame allocator (PFA) using bitmap-based tracking for 4GB address space
• Support for dynamic allocation/deallocation with memory map parsing from multiboot bootloader
• Virtual memory allocator (VMA) with page directory/page table management
• Manual page table creation with recursive page directory mapping for virtual-to-physical translation
• Proper TLB invalidation handling

Interrupt Handling Infrastructure

• Interrupt Descriptor Table setup
• Assembly stubs for stack frame management and End-of-Interrupt signaling
• Exception handlers for page faults, double faults, and other CPU exceptions
• PIC (Programmable Interrupt Controller) configuration and remapping
• Hardware interrupt support including keyboard input handling

Memory-Safe Kernel Architecture

• Higher-half kernel mapping (0xC0000000+) for protected memory space
• Stack management and protection
• Reservation of system memory regions (BIOS areas, VGA memory, kernel space)

Low-Level System Initialization

• GDT (Global Descriptor Table) setup with multiple privilege levels
• Paging implementation with both identity mapping and higher-half mapping
• Transition from assembly bootloader to C execution environment

Development Period

July - August 2025

Feature examples

Post initialization screen

Basic allocation

Build instructions

Run the default make target