[erlang-questions] how can I make nif shared libraries

Tony Rogvall <>
Wed Dec 22 21:06:51 CET 2010

Hi joe!

To compile for multiple architectures on mac-os-x I use the flags

-arch i386 -arch x86_64

instead of -m32.

This makes it possible to use the driver or nif shared object with both 32- or 64-bit erlang.

To link with other shared libraries you need to add

-L<path> -l<name>

Sometimes it gets a bit more complicated than this, but this should be enough for you?
I sometimes revert to link the the code instead of using shared libraries. Then you 
do not have to think about dependencies.

Hope it works


On 22 dec 2010, at 20.49, Joe Armstrong wrote:

> How do link shared libraries with nifs?
> I want to make a few nifs and put them in a shared library.
> The problem is that the my nif library in its turn calls things in
> other shared libraries. And when I load my nif library the other
> referenced shared libraries
> are not loaded.
> I made a little example to illustrate this:
> I have a file niftest.c with the following nif
>   extern int other_lib_mult(int, int);
>   static ERL_NIF_TERM mult(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
>   {
>      int a,b,c;
>      enif_get_int(env, argv[0], &a);
>      enif_get_int(env, argv[0], &b);
>      c = other_lib_mult(a, b);
>      return enif_make_int(env, c);
>   }
> I make a shared library called niftest.so
> with this command
> gcc -m32 -O3 -fPIC -bundle -flat_namespace -undefined suppress
> -fno-common -Wall -o niftest.so niftest.c -I
> /usr/local/lib/erlang/usr/include/
> Which makes the shared library.
> other_lib_mult is is lib.c and I make a shared library lib.so with a
> similar command to the above
> When I try to load niftest.so erlang says
> {error,{load_failed,"Failed to load NIF library: 'dlopen(./niftest.so,
> 2): Symbol not found: _other_lib_mult\n  Referenced from:
> /Users/joe/code/nifs/nif2/niftest.so\n  Expected in: flat namespace\n
> in /Users/joe/code/nifs/nif2/niftest.so'"}}
> This is running on mac os-x.
> Also do all the shared libraries have to be compiled for 32 bit, or
> can I pick and mix
> with 64 bit code. Without the -m32 flag nothing works and some of the
> shared libraries
> I want to call were compiled as 64 bit.
> Cheers
> /Joe
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