How to probe a modem exposing virtual ports (GSM 07.10 muxed ports)

Aleksander Morgado aleksandermj at
Tue May 7 09:14:05 UTC 2024


> I am in the same situation and my Quectel BG770A-GL modem is using the
> EMUX instead of the standard CMUX mode.
> Quectel is only providing full PPP support for this EMUX mode and so
> would like to know what could be
> the best way to add support for thoses /dev/pts virtual devices in MM ?
> Im using ModemManager 1.18, is it possible to "force" a port (without
> udev) in MM ?

I have not done any testing myself with this kind of ptys, but I don't
think it should be very difficult to support them, at least e.g.
You can try to run the MM daemon with --test-no-udev, and then use
mmcli --report-kernel-event to notify about the port additions as if
they were notified by udev. See e.g.

This approach *won't work* by default for ptys, but it may give you an
initial way forward if you want to start testing custom MM changes to
adjust the port probing to support these device types. The
MMKernelDevice objects will need to be adjusted to support these
device types that don't have a direct counterpart entry in sysfs.


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