问题
I have the following source snippet from a book that I'm reading now. So I created an asm file and typed exactly. Then used nasm command (nasm -f elf test.asm) then tried to compile into an executable file by using gcc (gcc test.o -o test) then I get the following error.
Error:
ld: warning: ignoring file test.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
Source code:
[BITS 16]
[SECTION .text]
START:
mov dx, eatmsg
mov ah, 9
int 21H
mov ax, 04C00H
int 21H
[SECTION .data]
eatmsg db "Eat at Joe's!", 13, 10, "$"
I guess the source code is not compatible with current generation of CPUs (the book is old...).
How do I fix this source code to run under x86_64 CPUs ?
回答1:
If you want to continue using that old book to learn the basics (which is just fine, nothing wrong with learning the basics/old way before moving on to modern OS), you can run it in DOSBox, or a FreeDOS VM.
回答2:
That's a 16 bits code, it was made to create pure binary code and not executables. You cannot run it on modern OSs like Linux without heavy modifications. And btw, that's an MS-DOS assembly, which will not work for Linux anyway (using int 21h which are MS-DOS services).
If you want to learn assembly, I suggest getting a more modern book, or setting up a virtual machine in which to learn with your book (although learning 16-bits assembly is really not useful nowadays).
回答3:
First of all the code contains interrupts which will work in real mode only and in DOS (int 21h with values in regs), and linux works in protected mode, you cannot call these interrupts directly.
Next the code is 16 bit code, to make it a 64 bit code you need [BITS 64]
Third you have no entry point to the code. To make one you can write a main function in C and then call the starting label as a function in the assembly code.
Have a look at this thing: PC Assembly Language by Paul A. Carter
来源：https://stackoverflow.com/questions/7254370/how-to-compile-this-asm-code-under-linux-with-nasm-and-gcc