To compile boot.asm use nasm compiler
command => nasm -f bin boot.asm -o boot.bin
Use QEMU as Simulator
command => qemu-system-x86_64 boot.bin
Setup Cross Compiler => Google Osdev Wiki GCC Cross Compiler This will setup binutils and gcc cross compiler
Debug via gdb =>
gdb add-symbol-file ./build/kernel.a 0x100000 set breakpoint break kernel_main target remote | qemu-system-x86_64 -S -gdb stdio -hda ./bin/mukku.bin