OSDev.org

Posted: **Fri May 08, 2020 10:57 am**

I have created a custom bootloader and created the kernel in c++ following the osdev wiki. When I try to compile the assembly with

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nasm.exe -f win64 boot.asm -o boot.obj

, compile the kernel.cpp to kernel.obj, and link it with

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~\tdm-gcc64\c++.exe -T linker.ld -o Boot.img -ffreestanding -nostdlib boot.obj kernel.obj

it will have extra "This program cannot be run in DOS mode" I also don't know how to set it to start at 0x7c00 as

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org 0x7c00

doesn't work unless in binary format. Any help will be appreciated.

Posted: **Fri May 15, 2020 2:45 am**

You're using a compiler targeted towards Windows, so it creates Windows EXE files by default. Does your linker script tell it you want a flat binary?

I strongly recommend using a cross-compiler. It's much easier to get help with your compiler when you're using the same compiler that everyone else is using.

OSDev.org

exporting nasm code as win64 causes it to add extra junk

exporting nasm code as win64 causes it to add extra junk

Re: exporting nasm code as win64 causes it to add extra junk