Bug #6118
openosmo-pcu assigns multi-slot TBFs over PACCH to MS with unknwon ms_class
0%
Description
When the DL/UL TBF assignment happens over CCCH (PCH, AGCH) we don't have this problem, since assignment over CCH can only assign a single TS.
However, once that TBF is assigned and MS jumps to packet-active mode (PDCH), new TBF assignment can happen over PACCH.
It can be that at that point in time, the PCU doesn't know the MultiSlot Class of the MS, because the MS used 1phase access (aka no PktResourceReq containing RadioAccessCap) and the SGSN didn't provide the PCU with it during BSSGP-DL-UNITDATA (because it neither knows it).
As a result, when allocating a DL TBF at that time, the current alloc_algo, if the ms_class is not known (=0), it assumes ms_class=12:
#define DEFAULT_MSLOT_CLASS 12
As a result, it ends up assigning up to 4 TS to an MS which may not support it (eg. because it's ms_class=1 but didn't inform the PCU about it, like "modem" osmocom-bb app currently).
Current behavior basically breaks proper operation of MS with ms_class<12 (fortunately most MS nowadays are ms_class=12 or higher).
