Create object file from kernel.asm and kernel.c and then link it using our linker script.

nasm -f elf32 kernel.asm -o kasm.o

Will run the assembler to create the object file kasm.o in ELF-32 bit format:

gcc -m32 -c kernel.c -o kc.o

The -c option makes sure that after compiling, linking doesn't implicitly happens:

ld -m elf_i386 -T link.ld -o kernel kasm.o kc.o

Will run the linker with our linker script and generate the executable.

qemu-system-i386 -kernel kernel

Will load the kernel in the QEMU emulator