fi_eq_read(3) on Linux
The text a24bca1851aa, as Debian 10 (Buster) shipped it.
Event queue operations fi_eq_open / fi_close : Open/close an event queue fi_control : Control operation of EQ fi_eq_read / fi_eq_readerr : Read an event from an event queue fi_eq_write : Writes an event to an event queue fi_eq_sread : A synchronous (blocking) read of an event queue fi_eq_strerror : Converts provider specific error information into a printable string