- * The SIG_SINGLE bit is reserved for a special purpose (this is
- * more a suggestion than a constraint). When a process wants
- * wait for a single event on the fly, it needs not allocate a
- * free signal from its pool. Instead, SIG_SINGLE can be used
- *
- * The "event" module is a higher-level interface that can optionally
- * deliver signals to processes. Messages provide even higher-level
- * IPC services built on signals. Semaphore arbitration is also
- * implemented using signals.
- *
- * Signals are very low overhead. Using them exclusively to wait
- * for multiple asynchronous events results in very simple dispatch
- * logic with low processor and resource usage.
- *
+ * \section sig_single SIG_SINGLE
+ *
+ * The SIG_SINGLE bit is reserved as a convenient shortcut in those
+ * simple scenarios where a process needs to wait on just one event
+ * synchronously. By using SIG_SINGLE, there's no need to allocate
+ * a specific signal from the free pool. The constraints for safely
+ * accessing SIG_SINGLE are:
+ * - The process MUST sig_wait() exclusively on SIG_SINGLE
+ * - SIG_SIGNAL MUST NOT be left pending after use (sig_wait() will reset
+ * it automatically)
+ * - Do not sleep between starting the asynchronous task that will fire
+ * SIG_SINGLE, and the call to sig_wait().
+ * - Do not call system functions that may implicitly sleep, such as
+ * timer_delayTickes().