CreateOS

A minimal x86 kernel written from scratch in C and assembly. GRUB loads it via the Multiboot spec, and it boots in QEMU and writes to the screen through VGA text memory.

GRUB (Multiboot) → boot/boot.s (_start) → kernel_main() → VGA text buffer @ 0xB8000

How it works

File	Role
boot/boot.s	Multiboot header (magic 0x1BADB002, flags, checksum) and the _start entry point, which calls kernel_main and then halts with cli; hlt
kernel/kernel.c	Freestanding C kernel: writes a string straight into VGA text memory at 0xB8000 (character byte + attribute byte 0x07)
linker.ld	Loads the kernel at 1 MiB and puts the .multiboot section first so GRUB can find the header
Makefile	Builds kernel.elf, packs it into a bootable ISO with grub-mkrescue and starts QEMU

Build and run

Requirements: an i686-elf cross compiler, grub-mkrescue (plus xorriso) and qemu-system-x86_64.

make run     # build → ISO → boot in QEMU
make iso     # only build build/CreateOS.iso
make clean

On boot the screen shows Hello from CreateOS!.

Roadmap

• GDT and IDT setup
• Keyboard and timer interrupts (PIC/PIT)
• Physical memory manager and paging
• VGA terminal driver with scrolling and printf
• Screenshot/GIF of the QEMU boot in this README

src/ contains early experiments and is not part of the build.

License

MIT