Are object files platform independent?

Question

Is it possible to compile program on one platform and link with other ? What does object file contain ? Can we delink an executable to produce object file ?

Answer 1

It doesn't need to be said again: C/C++ object files aren't portable.

On the other hand, ANSI C is one of the most portable languages there is. You may not be able to pick up your object files, but recompiling your source is likely to work if you stick to the ANSI C standard. This might also be true of C++ as well.

I don't know how universal GNU C++ is, but if you can compile with gcc on one computer you're good to go on any other machine that also has gcc installed. Just about every machine you can think of has a C compiler. That's portability.

Answer 2

I just wanted to say that as long as they use the same processor architecture and object format, as well as calling convention(usually nowadays, the processor maker creates one), there are many chances for object files to work interchangeably.

However, even in C the compiler makes some assumptions about certain library functions like stack protection(that I know of) being present, which need not be the same on both platforms. in the case that such code is generated, the objects will not be directly compatible.

System calls are not really relevant as long as the systems share them at all as normally they are called through C wrappers in the standard libraries.

In the end this only applies to C and very similar OSes like Linux and the BSDs, but it can happen.

Answer 3

No. In general object file formats might be the same, e.g. ELF, but the contents of the object files will vary from system to system.

An object file contains stuff like:

Object code that implements the desired functionality
A symbol table that can be used to resolve references
Relocation information to allow the linker to locate the object code in memory
Debugging information

The object code is usually not only processor specific, but also OS specific if, for example, it contains system calls.

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Edit:

Is it possible to compile program on one platform and link with other ?

Absolutely. If you use a cross-compiler. This compiler specifically targets a platform and generates object files (and programs) that are compatible with the target platform. So you can use an X86 Linux system, for example, to make programs for a powerpc or ARM based system using the appropriate cross compiler. I do it here.