Cellular Network Infrastructure » Core Network (CN) » OsmoSGSN

We should at some point move osmo-sgsn to use libosmo-gprs-{llc,sndcp}, in order to simplify and get rid of lots of code in osmo-sgsn as well as doing proper separation of layers.

The current state of osmo-sgsn, full of layer violations, make this task difficult.

A WIP branch is already available in osmo-sgsn.git "pespin/libosmo-gprs", but it still lacks some work in order to work, which should be done previously (and then the branch rebased on top).
For instance, #5852 should be done beforehand so that we avoid having to pass BVCI and NSEI all across the stack. This is needed beforehand because once we start using libosmogprs, there's no proper way to pass those across the stack (as expected). Hence, right now the WIP branch simply sets those to 0 when transmitting back to the PCU, which fails at BSSGP/NS layer.

• Get rid of "llme" and "lle" structs in osmo-sgsn code. The llme stuff in use can really be merged into the "mmctx" struct.