Hi all!

I've pushed the current state of GPRS support into the 'gprs' branch. All the 'core' changes related to GPRS are already in master, so it mainly really adds the GPRS protocols (gprs_{ns,bssgp,llc}.[ch]) as well as the handling of the most importnat 04.08 GMM messages (gsm_04_08_gprs.[ch]) as well as the state management for the SGSN MM context (gprs_sgsn.[ch]).

The status of the code is as follows: * NS link and BSSGP link are established between OpenBSC and the nanoBTS * LLC frames from the MS get delivered to the OpenBSC LLC code * GMM messages sent over LLC are delivered to the GMM code * The GMM code tries to respond with useful answers, permitting GPRS attach as well as routing area update

What's missing: * any kind of GGSN functionality, i.e. gatewaying to PPP daemon for actual user payloads * persistant storage of SGSN MM context information, especially the attach/detach status, routing area and P-TMSI of a subscriber * PDP context activation/deactivation * flow control for the BTS as well as for each MS (BSSGP level) * retransmissions and things like acknowledged mode of LLC * support for multiple BTS

There's really only one extremely ugly hack in the code right now, and that is that the IP address of the BTS is hard-coded in the ipac_gprs_send() function. You will have to enter the IP address of your BTS there to make packets in the SGSN->BTS direction delivered.

Apart from that, I think the code is at a state where other interested developers can start playing with it. I am leaving to Korea on a customer assingment tomorrow and will unlikely have time to work on any GPRS code throughout the next two weeks.

To get the code going, you should do the following things: * chceck out the gprs branch * hard-code your ip address into ipac_gprs_send() as indicated above * change your openbsc.cfg to use the last timeslot (TS 7) as "TCH/F_PDCH" instead of just "TCH/F"

Patches / Bug reports / ... welcome

Regards, Harald