Issue with 5G Slices and Bearer Connection Failure on Telit FN990 Modem

[Pradeep Gopanapalli]

Hello,

I am trying to establish multiple 5G multiplex slices on a Telit FN990
modem running in QMI mode. These 5G slices represent multiple PDNs managed
by ModemManager (via mmcli).

When using the "--test-multiplex-requested" option, the bearer setup fails
with the following Netlink error:

GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._g_2dio_2derror_2dquark.Code0:
failed to create net link for device: failed to add link for device:
Could not allocate link: Failed to add link with mux id 1: Netlink
message with transaction 9 failed

------------------------------

*Environment:*

   - *Modem*: Telit FN990A28 in *QMI mode*
   - *ModemManager*: 1.22.0
   - *libqmi*: 1.34.0-2
   - *libmbim*: 1.30.0-2
   - *Kernel*: 5.15.150
   - *OpenWrt*: Based on 22.03 using netifd

------------------------------

*Debug Logs During Bearer Connection:*

*(PFA message_modem_debug)*
*2024-12-28T00:38:03.709* DEBUG daemon ModemManager[9676]:
[1735346283.709521] [modem0/bearer1] connecting...
*2024-12-28T00:38:03.709* NOTICE daemon ModemManager[9676]:
[1735346283.709796] [modem0] state changed (registered -> connecting)
*2024-12-28T00:38:03.709* DEBUG daemon ModemManager[9676]:
[1735346283.709904] [modem0/bearer1] launching connection with QMI port
(cdc-wdm0) and data port (wwan0) (multiplex requested)
*2024-12-28T00:38:03.709* DEBUG daemon ModemManager[9676]:
[1735346283.709916] [cdc-wdm0/qmi] bringing down data interface 'wwan0'
*2024-12-28T00:38:03.710* DEBUG daemon ModemManager[9676]:
[1735346283.710309] [cdc-wdm0/qmi] resetting expected kernel data format to
802.3 in data interface 'wwan0'
*2024-12-28T00:38:03.897* WARN daemon ModemManager[9676]:
[1735346283.897197] [modem0/bearer1] connection attempt #1 failed: failed
to create net link for device: failed to add link for device: Could not
allocate link: Failed to add link with mux id 1: Netlink message with
transaction 1 failed
*2024-12-28T00:38:03.898* NOTICE daemon netifd: CELL1 (19170): error:
couldn't connect the modem:
'GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._g_2dio_2derror_2dquark.Code0:
failed to create net link for device: failed to add link for device: Could
not allocate link: Failed to add link with mux id 1: Netlink message with
transaction 1 failed'
------------------------------

*Similar Issue Reported:*

This issue has been reported in the following GitLab issue:
GitLab ModemManager Issue #533
<https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/533>,
but I have not seen a resolution for it.

*Reference Links:*

   - ModemManager Mailing List - March 2022
   <https://lists.freedesktop.org/archives/modemmanager-devel/2022-March/009191.html>

Any assistance or suggestions on resolving this issue would be greatly
appreciated.

Thanks,
*Pradeep G*

-- 
This electronic communication and the information and any files transmitted 
with it, or attached to it, are confidential and are intended solely for 
the use of the individual or entity to whom it is addressed and may contain 
information that is confidential, legally privileged, protected by privacy 
laws, or otherwise restricted from disclosure to anyone else. If you are 
not the intended recipient or the person responsible for delivering the 
e-mail to the intended recipient, you are hereby notified that any use, 
copying, distributing, dissemination, forwarding, printing, or copying of 
this e-mail is strictly prohibited. If you received this e-mail in error, 
please return the e-mail to the sender, delete it from your computer, and 
destroy any printed copy of it.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/libmbim-devel/attachments/20241229/25378a11/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: messages_modem_debug
Type: application/octet-stream
Size: 1289781 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/libmbim-devel/attachments/20241229/25378a11/attachment-0001.obj>