operating system

step 1

cd boot/
nasm main.asm -f bin -o main.bin

step 2

cd ../kernel/

gcc --ffreestanding -c kernel.c -o kernel.o

ld -o kernel.bin -Ttext 0x1000 kernel.o --oformat binary

step 3

cd .. 
cat boot/main.bin kernel/kernel.bin > os-image

step 4

qemu-system-x86_64 -fda os-image