new mapping method for example aarch64

    return res;

};

#if defined(__LP64__) && !defined(__x86_64__)

   __attribute__((visibility("hidden"))) static uintptr_t next_mem_pos_;

#endif

__attribute__((visibility("hidden"))) uint32_t map32(uint32_t size){

#ifdef X86_64

    return mmap(0,size,PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_32BIT, -1, 0);

#else

    return mmap(0,size,PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);

#endif

#if defined(__LP64__) && !defined(__x86_64__)

  // MAP_32BIT only available on x86_64.

  void* actual = MAP_FAILED;

  std::string strerr;

  if (low_4gb && expected == nullptr) {

    flags |= MAP_FIXED;

    for (uintptr_t ptr = next_mem_pos; ptr < 4 * GB; ptr += kPageSize) {

      uintptr_t tail_ptr;

      // Check pages are free.

      bool safe = true;

      for (tail_ptr = ptr; tail_ptr < ptr + page_aligned_byte_count; tail_ptr += kPageSize) {

        if (msync(reinterpret_cast<void*>(tail_ptr), kPageSize, 0) == 0) {

          safe = false;

          break;

        } else {

          DCHECK_EQ(errno, ENOMEM);

        }

      }

      next_mem_pos_ = tail_ptr;  // update early, as we break out when we found and mapped a region

      if (safe == true) {

        actual = mmap(reinterpret_cast<void*>(ptr), page_aligned_byte_count, prot, flags, fd.get(),

                      0);

        if (actual != MAP_FAILED) {

          break;

        }

      } else {

        // Skip over last page.

        ptr = tail_ptr;

      }

    }

    if (actual == MAP_FAILED) {

      strerr = "Could not find contiguous low-memory space.";

    }

  } else {

        actual = mmap(expected, page_aligned_byte_count, prot, flags, fd.get(), 0);

        strerr = strerror(errno);

  }

  return actual;

#endif

};