compiling a C++ program using g++ with x86 settings

[aryan_]

Hi All,

How can I compile a C++ application using g++ with x86 platform settings on a x86_64 machine ?

What are the possible negative side-effects of compiling a C++ application with x86 settings on a x86_64 platform ?

I am using 64-bit Ubuntu 9.10.

Thanks.

[gerard4143]

I think -m32 will do it

g++ filename -m32 -o filename

[aryan_]

I think -m32 will do it

g++ filename -m32 -o filename

I already tried that.

However, when it comes to linking, gcc came across the 32-bit versions of the libraries where it expected the 64-bit ones.

Should I make -m32 a linker option as well ?

[Rubberman]

I already tried that.

However, when it comes to linking, gcc came across the 32-bit versions of the libraries where it expected the 64-bit ones.

Should I make -m32 a linker option as well ?

Well, with the -m32 option (or -m32-bit option) the compiler should pass the 32-bit info to the linker, so it should link with the 32-bit versions. In fact, you are basically building for a 32-bit environment, so all required libraries should be available in their 32-bit version, otherwise you have a 32-bit program that will only run on a 64-bit machine...

[aryan_]

Well, with the -m32 option (or -m32-bit option) the compiler should pass the 32-bit info to the linker, so it should link with the 32-bit versions.

I added -m32 to the linker options as well, and it successfully linked against the 32-bit library. Otherwise, it was complaining about the "incompatible" library, and aborting the linking process. So, somehow, compiler did not pass 32-bit info to the linker before.

[Rubberman]

Were you using gcc/g++ to do the linkage, or directly going to ln?

[aryan_]

Were you using gcc/g++ to do the linkage, or directly going to ln?

I was using gcc.

[Rubberman]

Oops, I meant ld not ln. So, you probably needed to add the -Wl,-m32 option to pass to the linker, correct?

[aryan_]

Oops, I meant ld not ln. So, you probably needed to add the -Wl,-m32 option to pass to the linker, correct?

Yes. I added -m32 to linker options.

[Rubberman]

Ok. Then if I were you I'd post this issue as a possible bug to the gcc / gnu / FSF web site's bug page. I'd think, personally, that the -w32 option to the compiler should be passed as necessary to the linker.