[RFC] TTY port locked problems when using PPP

[Piotr Figiel]

Hi Aleksander,

wt., 18 cze 2019 o 14:43 Aleksander Morgado <aleksander at aleksander.es>
napisał(a):

> My opinion is a bit open on this, I liked the first way because we
> would try to be as robust as possible and totally avoid using the port
> with wrong CLOCAL settings, but I don't think we can have that
> robustness unless we're truly in sync with NM and pppd, and for that
> we need either #2 or #3. And if we target to be in sync, then I don't
> think #1 is needed, we should always try to enforce being in sync
> instead. I'd vote to have #2 in MM 1.8 and MM 1.10 and #3 for the next
> MM 1.12?
>
> Comments welcome!

Maybe this is too bold, but did you consider starting pppd from
ModemManager? It seems to me that the dance around the shared resource
which is tty port in this case with NetworkManager will always be
error prone. And with pppd being actually low-level detail related
with certain modems it's kind of leaky abstraction that the NM has to
start it for the network interface to appear (once MM will make the
port ready). I don't think NM has to do anything similarly special
around qmi or mbim modems.

Best regards,
Piotr.