I'm trying to run a basic assembly file using 64 Bit Mac OS X Lion, using nasm and ld which are installed by default with Xcode.
I've written an assembly file, which prints a character, and I got it to build using nasm.
nasm -f elf -o program.o main.asm
However, when I go to link it with ld, it fails with quite a few errors/warnings:
ld -o program program.o
ld: warning: -arch not specified
ld: warning: -macosx_version_min not specificed, assuming 10.7
ld: warning: ignoring file program.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: symbol dyld_stub_binder not found, normally in libSystem.dylib
ld: entry point (start) undefined. Usually in crt1.o for inferred architecture x86_64
So, I tried to rectify a few of these issues, and got nowhere.
Here's one of things I've tried:
ld -arch i386 -e _start -o program program.o
Which I thought would work, but I was wrong.
How do you make the object file a compatible architecture that nasm and ld will agree with?
Also, how would you define the entry point in the program (right now I'm using global _start in .section text, which is above _start, which doesn't seem to do much good.)
I'm a bit confused as to how you would successfully link an object file to a binary file using ld, and I think I'm just missing some code (or argument to nasm or ld) that will make them agree.
Any help appreciated.