Say Y here if you want to build support for the IrDA (TM) protocols. The Infrared Data Associations (tm) specifies standards for wireless infrared communication and is supported by most laptops and PDA's. To use Linux support for the IrDA (tm) protocols, you will also need some user-space utilities like irattach. For more information, see the file <file:Documentation/networking/irda.txt>. You also want to read the IR-HOWTO, available at <http://www.tldp.org/docs.html#howto>. If you want to exchange bits of data (vCal, vCard) with a PDA, you will need to install some OBEX application, such as OpenObex : <http://sourceforge.net/projects/openobex/> To compile this support as a module, choose M here: the module will be called irda.
Say Y here to support the connectionless Ultra IRDA protocol. Ultra allows to exchange data over IrDA with really simple devices (watch, beacon) without the overhead of the IrDA protocol (no handshaking, no management frames, simple fixed header). Ultra is available as a special socket : socket(AF_IRDA, SOCK_DGRAM, 1);
Say Y here if you want IrLMP to cache the last LSAP used. This makes sense since most frames will be sent/received on the same connection. Enabling this option will save a hash-lookup per frame. If unsure, say Y.
Say Y here is you want IrLAP to send fast RR (Receive Ready) frames when acting as a primary station. Disabling this option will make latency over IrDA very bad. Enabling this option will make the IrDA stack send more packet than strictly necessary, thus reduce your battery life (but not that much). Fast RR will make IrLAP send out a RR frame immediately when receiving a frame if its own transmit queue is currently empty. This will give a lot of speed improvement when receiving much data since the secondary station will not have to wait the max. turn around time (usually 500ms) before it is allowed to transmit the next time. If the transmit queue of the secondary is also empty, the primary will start backing-off before sending another RR frame, waiting longer each time until the back-off reaches the max. turn around time. This back-off increase in controlled via /proc/sys/net/irda/fast_poll_increase If unsure, say Y.
Say Y here if you want the IrDA subsystem to write debug information to your syslog. You can change the debug level in /proc/sys/net/irda/debug . When this option is enabled, the IrDA also perform many extra internal verifications which will usually prevent the kernel to crash in case of bugs. If unsure, say Y (since it makes it easier to find the bugs).