+ tag_field_generic = lttng_ust_dynamic_type_tag_field();
+ tag_type = &tag_field_generic->type;
+
+ /* Serialize enum field. */
+ strncpy(tag_field_name, lf->name, LTTNG_UST_SYM_NAME_LEN);
+ tag_field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
+ strncat(tag_field_name,
+ "_tag",
+ LTTNG_UST_SYM_NAME_LEN - strlen(tag_field_name) - 1);
+ tag_field.type = *tag_type;
+ ret = serialize_one_field(session, fields, iter_output,
+ &tag_field);
+ if (ret)
+ return ret;
+
+ /* Serialize variant field. */
+ uf = &fields[*iter_output];
+ ret = lttng_ust_dynamic_type_choices(&nr_choices, &choices);
+ if (ret)
+ return ret;
+
+ strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
+ uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
+ uf->type.atype = ustctl_atype_variant;
+ uf->type.u.variant.nr_choices = nr_choices;
+ strncpy(uf->type.u.variant.tag_name,
+ tag_field_name,
+ LTTNG_UST_SYM_NAME_LEN);
+ uf->type.u.variant.tag_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
+ (*iter_output)++;
+
+ /* Serialize choice fields after variant. */
+ for (i = 0; i < nr_choices; i++) {
+ ret = serialize_one_field(session, fields,
+ iter_output, &choices[i]);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
+static
+int serialize_one_field(struct lttng_session *session,
+ struct ustctl_field *fields, size_t *iter_output,
+ const struct lttng_event_field *lf)
+{
+ const struct lttng_type *lt = &lf->type;
+ int ret;
+
+ /* skip 'nowrite' fields */
+ if (lf->nowrite)
+ return 0;
+