+ if (!chan->sc_compat_unknown) {
+ struct lttng_kernel_event ev;
+ const struct lttng_event_desc *desc =
+ &__event_desc___compat_sys_unknown;
+
+ memset(&ev, 0, sizeof(ev));
+ strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN);
+ ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0';
+ ev.instrumentation = LTTNG_KERNEL_NOOP;
+ chan->sc_compat_unknown = ltt_event_create(chan, &ev, filter,
+ desc);
+ if (!chan->sc_compat_unknown) {
+ return -EINVAL;
+ }
+ }
+