Public bug reported:
Hello,
I would like to report a compatibility issue with the Fibocom L850 LTE modem
(Intel XMM7360) affecting the ModemManager version currently provided by
Ubuntu 24.04 Noble.
The issue was reproduced on Linux Mint 22.3, which is based on Ubuntu
Noble.
Hardware
========
Laptop:
HP EliteBook 830 G7
WWAN modem:
Fibocom L850 LTE Module / Intel XMM7360
PCI ID:
8086:7360
Subsystem:
103c:8337
Kernel driver:
iosm
Mobile provider used for testing:
HoT Austria
APN:
internet.t-mobile.at
No IMEI, IMSI or ICCID is included in this report.
Affected system
===============
Distribution:
Linux Mint 22.3, Ubuntu 24.04 Noble based
Kernel:
7.0.0-28-generic
Ubuntu ModemManager package installed:
modemmanager 1.23.4-0ubuntu2
Package source:
Ubuntu Noble main repository
apt-cache policy modemmanager reports:
Installed: 1.23.4-0ubuntu2
Candidate: 1.23.4-0ubuntu2
Repository: noble/main
Actual behaviour with ModemManager 1.23.4
=========================================
The modem itself is detected by ModemManager, but initialization does not
complete correctly.
Observed symptoms include:
- SIM card incorrectly reported as "SIM not inserted"
- modem enters sim-missing / failed state
- AT communication timeouts
- wwan0xmmrpc0 reported as an unhandled port type
- LTE connection cannot be established
Typical messages included:
SIM not inserted
sim-missing
wwan0at1 timed out
wwan0xmmrpc0 ... unhandled port type
The iosm kernel driver exposes the following WWAN devices:
/dev/wwan0at0
/dev/wwan0at1
/dev/wwan0xmmrpc0
The data interface is:
wwan0
Expected behaviour
==================
The Fibocom L850 / Intel XMM7360 should:
- detect the inserted SIM correctly
- initialize the XMMRPC interface
- register on the LTE network
- allow NetworkManager to establish a mobile broadband connection
Ubuntu 26.04 Live comparison
============================
I tested exactly the same laptop, modem and SIM using an Ubuntu 26.04 Live
system.
The Ubuntu 26.04 Live environment used:
Kernel:
7.0.0-14-generic
ModemManager:
1.25.95
In this environment the modem worked correctly.
The relevant ports were detected as:
wwan0 net
wwan0at1 at
wwan0xmmrpc0 xmmrpc
wwan0at1 was used as the primary AT port.
The SIM was detected correctly.
A 3GPP network scan found the available Austrian networks, including:
23203 - Magenta / HoT
23201 - A1
23205 - Drei
Registration to PLMN 23203 succeeded.
The modem then reported:
operator code: 23203
operator name: HoT
registration state: home
access technology: LTE
A NetworkManager GSM connection using the APN:
internet.t-mobile.at
successfully established an LTE data connection.
Testing ModemManager 1.25.95 on the affected system
===================================================
To determine whether the kernel was responsible, I built ModemManager
1.25.95 and tested it on the original Linux Mint 22.3 installation.
I also observed a difference in the WWAN udev properties.
On the working Ubuntu 26.04 Live environment, the AT ports had:
ID_MM_PORT_TYPE_AT_PRIMARY=1
This property was not present by default on the affected Linux Mint /
Ubuntu Noble based installation.
For testing, I added:
SUBSYSTEM=="wwan", KERNEL=="wwan0at0", ENV{ID_MM_PORT_TYPE_AT_PRIMARY}="1"
SUBSYSTEM=="wwan", KERNEL=="wwan0at1", ENV{ID_MM_PORT_TYPE_AT_PRIMARY}="1"
I then ensured that ModemManager 1.25.95 was the first ModemManager instance
to access the modem after a complete power-off.
With ModemManager 1.25.95 the modem initialized correctly.
Detected configuration:
Primary AT port:
wwan0at1
Ports:
wwan0 net
wwan0at1 at
wwan0xmmrpc0 xmmrpc
The SIM was detected correctly.
LTE registration succeeded and NetworkManager was able to establish the
mobile broadband connection.
Cold boot verification
======================
I initially suspected that kernel 7.0.0-28 might be responsible for the
problem.
However, after configuring ModemManager 1.25.95 to start instead of
ModemManager 1.23.4, I performed a complete cold boot with the regular kernel:
7.0.0-28-generic
The laptop was completely powered off, left off for approximately 20-30
seconds, and then powered on again.
Without manual intervention:
- ModemManager 1.25.95 started automatically
- Fibocom L850 was detected
- SIM was detected correctly
- LTE registration occurred automatically
- NetworkManager connected automatically
- wwan0 received an IPv4 address
Final working modem state:
Kernel:
7.0.0-28-generic
ModemManager:
1.25.95
Primary port:
wwan0at1
Technology:
LTE
Operator:
HoT
PLMN:
23203
Registration state:
home
Mobile data:
connected
Conclusion
==========
The successful cold-boot test with kernel 7.0.0-28-generic indicates that
the kernel and iosm driver are fundamentally able to operate this modem.
The main difference between the failing and working configurations is the
ModemManager/XMM7360 handling and possibly the WWAN udev port properties.
Ubuntu Noble currently provides:
modemmanager 1.23.4-0ubuntu2
The same hardware works with ModemManager 1.25.95.
I therefore suspect that relevant Intel XMM7360 / XMMRPC support changes
between these ModemManager versions are missing from the Noble package.
Upstream report
===============
The issue has also been reported to the upstream ModemManager project:
https://gitlab.freedesktop.org/mobile-
broadband/ModemManager/-/work_items/1089
Request
=======
Could the relevant Intel XMM7360 / XMMRPC changes between ModemManager
1.23.4 and 1.25.95 be identified?
If the fix is suitable for Ubuntu Noble, could the required changes and/or
udev rules be backported to the Noble ModemManager package?
I can reproduce the setup and provide additional ModemManager debug logs,
udev information or command output if required.
Thank you.
** Affects: modemmanager (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2163071
Title:
Fibocom L850 / Intel XMM7360 fails with ModemManager 1.23.4 on Noble,
works with 1.25.95
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