You can just allocate a portion of a shared memory segment, copy the message to that buffer, send the offset of that portion of shared memory to another process, and you are done. Let's see the example:

#include <boost/interprocess/managed_shared_memory.hpp>
#include <cstdlib> //std::system
#include <sstream>

int main (int argc, char *[2] "MyName"[])
{
   using namespace boost::interprocess;
   if(argc == 1){  //Parent process
      //Remove shared memory on construction and destruction
      struct shm_remove
      {
         shm_remove() {  shared_memory_object::remove("MyName"); }
         ~shm_remove(){  shared_memory_object::remove("MyName"); }
      } remover;

      //Create a managed shared memory segment
      managed_shared_memory segment(create_only, "MyName", 65536);

      //Allocate a portion of the segment (raw memory)
      managed_shared_memory::size_type free_memory = segment.get_free_memory();
      void * shptr = segment.