ModemManager RAT definitions, etc.

[Alexey Orishko]

Hi guys,

I'm working on integrating LPWA modem and I got a few questions mostly
on conceptual level.

#1There is MMModemAccessTechnology which "Describes various access
technologies that a device uses when registered with or connected to a
network".
In addition to 27.007, there is also 3GPP TS 29.274 which defines the
following RAT Types: UTRAN, GERAN, WLAN, GAN, HSPA Evolution, EUTRAN
(WB-E-UTRAN), Virtual, EUTRAN-NB-IoT, LTE-M, NR. While 5GNR is defined
(however not sure if NSA and SA modes can be identified and stated), I
can't see any reference to LPWA technologies like Cat-M and Cat-NB.
This information could be easily acquired by +COPS? command (at least
I tried two different module vendors using different chipset vendors).
- How should LPWA modems be identified? (new LTE Categories enum,
change existing, etc)

#2 Related to topic above, currently LPWA modem identified as HSPA
(3G), however in reality 3G is not supported. Changing the way how RAT
is identified, would most likely ruin support for old modems in
plugin. Maybe some folks already faced a problem with command
incompatibility among  different modems in the same plugin.
- What approach would be preferable in solving AT command collision problem?

#3 related to above. Approx 10 years ago AT*CNTI was introduced to
check access tech in a generic code. it is a proprietary command not
supported by a many modems.
- Could it be moved to relevant plugins only? (especially in the light
of 3G sunset)

#4 Command "mmcli -m 0" in a segment "IP" states the following:
"supported: ipv4, ipv6, ipv4v6"
- Could someone clarify the meaning of it: is it "a list of supported
PDP context types" or "type of currently active/main PDP context"?

#5 Is there any particular reason that "build" directory is not
included in MM .gitignore file?

Just in case, when I read setup at
https://modemmanager.org/docs/contribution-guidelines/using-gitlab/developer-setup/,
I noticed that a text
"ModemManager: https://gitlab.freedesktop.org/username/ModemManager"
has hyperlink which actually points to docs page instead of git (I
dunno if it was by intention).

Thanks,
Alexey