x86 Bootable Kernel

Overview

A bootable x86 kernel written from scratch in C and Assembly, no operating system, no libraries, just raw hardware. Boots via GRUB using the Multiboot specification and renders text by writing directly to VGA video memory.

Key Technical Details

• Direct memory-mapped I/O — writes to VGA memory at 0xb8000 without any operating system abstraction layer
• Multiboot-compliant binary built using NASM assembler and GCC with a custom linker script positioning code at physical address 0x100000 for GRUB bootloader compatibility
• Hardware initialization including interrupt disabling via CLI instruction and 8KB stack allocation in BSS section for bare-metal execution
• VGA text mode interface writing 2-byte character-attribute pairs directly to video memory, demonstrating hardware-level display protocol understanding

What I Learned

This project was about understanding what happens between pressing the power button and seeing text on screen: the boot process, memory layout, segmentation, and how software communicates with hardware when there’s nothing else running.

Links

🔗 GitHub Repository