Bootloader in C won't compile

Question

I am a newbie in writing bootloaders. I have written a helloworld bootloader in asm, and I am now trying to write one in C. I have written a helloworld bootloader in C, but I ca

Answer 1

A bootloader is written in ASM.

When compiling C code (or C++, or whatever), a compiler will 'transform' your human readable code into machine code. So you can't be sure about the result.

When a PC boots, the BIOS will execute code from a specific address. That code needs to be executable, directly.

That's why you'll use assembly. It's the only way to have un-altered code, that will be run as written, by the processor.

If you want to code in C, you'll still have to code an ASM bootloader, which will be in charge to load properly the machine code generated by the compiler you use.

You need to understand that each compiler will generate different machine codes, that may need pre-processing before execution.

The BIOS won't let you pre-process your machine code. The PC boot is just a jump to a memory location, meaning the machine code located at this location will be directly executed.