libbsd.txt: Describe current state of WLAN.

libbsd.txt

@@ -1154,6 +1154,58 @@ The following is necessary to use PF on RTEMS:
   systems (on FreeBSD that means systems with less than 100 MB RAM). This is
   fixed in +pfctl_init_options()+.
 
+== Wireless Network (WLAN) ==
+
+The libbsd provides a basic support for WLAN. Note that currently this support
+is still in an early state. The following gives a rough overview over the
+necessary steps to connect to an encrypted network with an RTL8188EU based WiFi
+dongle:
+
+- Reference all necessary module for your BSP. For some BSPs this is already
+  done in the nexus-devices.h:
+
+----
+	SYSINIT_MODULE_REFERENCE(wlan_ratectl_none);
+	SYSINIT_MODULE_REFERENCE(wlan_sta);
+	SYSINIT_MODULE_REFERENCE(wlan_amrr);
+	SYSINIT_MODULE_REFERENCE(wlan_wep);
+	SYSINIT_MODULE_REFERENCE(wlan_tkip);
+	SYSINIT_MODULE_REFERENCE(wlan_ccmp);
+	SYSINIT_DRIVER_REFERENCE(rtwn_usb, uhub);
+	SYSINIT_REFERENCE(rtwn_rtl8188eufw);
+----
+
+- Create your wlan device using ifconfig:
+  +ifconfig wlan0 create wlandev rtwn0 up+
+
+- Start a wpa_supplicant instance for that device:
+  + wpa_supplicant_fork -Dbsd -iwlan0 -c/media/mmcsd-0-0/wpa_supplicant.conf+
+
+Note that the wpa_supplicant will only be active till the device goes down. A
+workaround is to just restart it every time it exits.
+
+=== Known restrictions ===
+
+- The network interface (e.g. wlan0) is currently not automatically created. It
+  would be nice, if some service would create it as soon as for example a USB
+  device is connected. In FreeBSD the names are assigned via rc.conf with lines
+  like +wlans_rtwn0="wlan0"+.
+
+- wpa_supplicant hast to be started after the device is created. It has to be
+  restarted every time the connection goes down. Instead of this behaviour,
+  there should be some service that starts and restarts wpa_supplicant
+  automatically if a interface is ready. Probably the dhcpcd hooks could be used
+  for that.
+
+- The current wpa_supplicant implementation is protected with a lock so it can't
+  be started more than one time. If multiple interface should be used, all have
+  to be handled by that single instance. That makes it hard to add interfaces
+  dynamically. wpa_supplicant should be reviewed thoroughly whether multiple
+  instances could be started in parallel.
+
+- The control interface of wpa_supplicant most likely doesn't work. The wpa_cli
+  application is not ported.
+
 == Problems to report to FreeBSD ==
 
 The MMAP_NOT_AVAILABLE define is inverted on its usage.  When it is