Keyboard notifier One can use register_keyboard_notifier to get called back on keyboard events (see kbd_keycode() function for details). The passed structure is keyboard_notifier_param: - 'vc' always provide the VC for which the keyboard event applies; - 'down' is 1 for a key press event, 0 for a key release; - 'shift' is the current modifier state, mask bit indexes are KG_*; - 'value' depends on the type of event. - KBD_KEYCODE events are always sent before other events, value is the keycode. - KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym. value is the keycode. - KBD_UNICODE events are sent if the keycode -> keysym translation produced a unicode character. value is the unicode value. - KBD_KEYSYM events are sent if the keycode -> keysym translation produced a non-unicode character. value is the keysym. - KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms. That permits one to inspect the resulting LEDs for instance. For each kind of event but the last, the callback may return NOTIFY_STOP in order to "eat" the event: the notify loop is stopped and the keyboard event is dropped. In a rough C snippet, we have: kbd_keycode(keycode) { ... params.value = keycode; if (notifier_call_chain(KBD_KEYCODE,¶ms) == NOTIFY_STOP) || !bound) { notifier_call_chain(KBD_UNBOUND_KEYCODE,¶ms); return; } if (unicode) { param.value = unicode; if (notifier_call_chain(KBD_UNICODE,¶ms) == NOTIFY_STOP) return; emit unicode; return; } params.value = keysym; if (notifier_call_chain(KBD_KEYSYM,¶ms) == NOTIFY_STOP) return; apply keysym; notifier_call_chain(KBD_POST_KEYSYM,¶ms); } NOTE: This notifier is usually called from interrupt context.