nvlist_add_descriptor
nvlist_add_descriptor(nvl, "s", s);
nvlist_add_descriptor(nvl, "stderr", STDERR_FILENO);
nvlist_add_descriptor(nvl, key, STDERR_FILENO);
nvlist_add_descriptor(nvl, "nvlist/descriptor/STDERR_FILENO", STDERR_FILENO);
nvlist_add_descriptor(nvl, "nvlist/descriptor", STDERR_FILENO);
nvlist_add_descriptor(nvl, "nvlist/descriptor", STDERR_FILENO);
nvlist_add_descriptor(nvl, "nvlist/descriptor", STDERR_FILENO);
nvlist_add_descriptor(nvl, "nvlist/descriptor/STDERR_FILENO", STDERR_FILENO);
nvlist_add_descriptor(nvl, "fd", 12345);
nvlist_add_descriptor(nvl, name, fd);
nvlist_add_descriptor(nvl, "nvlist/descriptor/STDERR_FILENO",
nvlist_add_descriptor(nvl, "nvlist/descriptor/pipe_rd", pfd[0]);
void nvlist_add_descriptor(nvlist_t *nvl, const char *name, int value);
nvlist_add_descriptor(nvl_filed, "f_file", filed->f_file);
nvlist_add_descriptor(nvl_filed, "f_procdesc",