> > attached, and connection managers (at least connman) start
> > to hammer us to connect a context, eventhough it happens
> > automatically in LTE.
> What happens automatically? Yes, it is true that you need a default
> context to attach to LTE. So activating a context is basically a part
> of the LTE attach procedure.
> But that default context does not need to be an internet context (e.g.
> Verizon uses (or used to) use an ims context for this). So ConnMan
> might need to activate an Internet context even if we're on LTE.
> To do that wouldn't we need to be able to flag attached even without
> registered context for LTE?
> Or will the modem not attach to 4G until the context is configured?
> I can not test that case with my modems.
It sort of depends on the configuration. But basically we will not get
on LTE without a default bearer. The default bearer configuration can
come from the modem itself, or actually from the network. That default
bearer is essentially an active context. This is why gprs.c goes to the
trouble of matching it against existing contexts, but if it isn't found,
then adds a new one (which is supposed to be transient/temporary).
Typically, on a well-configured system, you'll have the default bearer
setup via LongTermEvolution.DefaultAccessPointName and also provisioned
in the provisioning database. But as I mentioned earlier, the default
context doesn't have to be an internet one.
For the modem I use, it would be a bit messy to update the default APN on the fly,
because it requires to turn off the radio to change that. We have written it into
non volatile memory beforehand.
But anyway, you have convinced me so I think we can skip this patch,
I guess its just the matter of the order things happen and the time span will be very short.