Support for the Linux WWAN subsystem

Aleksander Morgado aleksander at
Mon Aug 30 09:00:49 UTC 2021

> > Is that wwan_hwsim integration to be able to create fake modems in
> > userspace that are exposed via the new WWAN subsystem? If so, wouldn't
> > they already be supported by the current ModemManager, which supports
> > the new WWAN subsystem?
> I suppose the answer should be "yes they are supported by the current
> MM". However, mmcli returns no modems.
> mmcli -L
> No modems were found

What MM version is that?

Also, which ports are exposed in the system? Just the wwan control
port, or do you also have a NET port as well for the same fake device?
MM requires both things.

The best way to debug this further would be to look at the MM daemon
debug logs, see

> > Please correct me if I'm wrong; openairinterface5g allows you to
> > simulate/implement the radio and 3GPP protocol side of a UE. But there
> > is no AT/QMI/MBIM control protocol implemented in openairinterface5g,
> > or is there?
> Yes. However I think we could leverage openairinterface5g by emulating
> the radio and 3GPP protocol too. My experience with mac80211_hwsim and
> more recently with mac802154_hwsim are very interesting. They
> basically allow us to run any application/implementation and move them
> to the real world with few or even no modifications. Why not have
> something similar with wwan_hwsim and 4G/5G? :)

Binding the AT/QMI/MBIM control port operations with the corresponding
actions in the 3GPP protocol stack would really be a fun project, but
it would probably be a huge task, beware!


More information about the ModemManager-devel mailing list