How to debug the very first part of kernel

I've read some kernel code recently, and I want to see how it actually works. I found a lot of articles about how to debug kernel with qemu, but all i found are about setting a breakpoint at start_kernel, so i wonder if there's way i can debug before start_kernel, those setup code and decompression code in arch/x86/boot folder. More specifically, I want to debug start at 0x200 offset of kernal image if I'm not misunderstanding boot protocol document. I would be appreciated for any reply and i'm sorry if i have weird english expression.