Public bug reported:

In Ubuntu 19.04 (and likely earlier) Modem Manager is installed with
filter policy 'strict' as opposed to 'default', which actually makes
Modem Manager _less_ strict regarding explicitly blacklisted ttys (see
man modemmanager).

This means that ttys, that are explicitly blacklisted from Modem Manager
by using ENV{ID_MM_DEVICE_IGNORE}="1" in its udev rule is still opened
and probed by Modem Manager although it should not.

This is a common cause of problems and frustrations for people working
with actual serial devices, e.g. within embedded development (e.g.
Arduino and the like). See https://nick.zoic.org/art/failed-to-set-dtr-
rts-systemd-modemmanager/ for an example.

A proposed solution is to change the following line in: 
/lib/systemd/system/ModemManager.service
from:
ExecStart=/usr/sbin/ModemManager --filter-policy=strict
to:
ExecStart=/usr/sbin/ModemManager --filter-policy=paranoid

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: modemmanager 1.10.0-1 [modified: 
lib/systemd/system/ModemManager.service]
ProcVersionSignature: Ubuntu 5.0.0-13.14-generic 5.0.6
Uname: Linux 5.0.0-13-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Thu May  2 15:35:58 2019
EcryptfsInUse: Yes
InstallationDate: Installed on 2018-05-26 (340 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: modemmanager
UpgradeStatus: Upgraded to disco on 2019-04-18 (13 days ago)

** Affects: modemmanager (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug disco

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to modemmanager in Ubuntu.
https://bugs.launchpad.net/bugs/1827328

Title:
  ModemManager does not honor blacklisted ttys (ID_MM_DEVICE_IGNORE)

Status in modemmanager package in Ubuntu:
  New

Bug description:
  In Ubuntu 19.04 (and likely earlier) Modem Manager is installed with
  filter policy 'strict' as opposed to 'default', which actually makes
  Modem Manager _less_ strict regarding explicitly blacklisted ttys (see
  man modemmanager).

  This means that ttys, that are explicitly blacklisted from Modem
  Manager by using ENV{ID_MM_DEVICE_IGNORE}="1" in its udev rule is
  still opened and probed by Modem Manager although it should not.

  This is a common cause of problems and frustrations for people working
  with actual serial devices, e.g. within embedded development (e.g.
  Arduino and the like). See https://nick.zoic.org/art/failed-to-set-
  dtr-rts-systemd-modemmanager/ for an example.

  A proposed solution is to change the following line in: 
/lib/systemd/system/ModemManager.service
  from:
  ExecStart=/usr/sbin/ModemManager --filter-policy=strict
  to:
  ExecStart=/usr/sbin/ModemManager --filter-policy=paranoid

  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: modemmanager 1.10.0-1 [modified: 
lib/systemd/system/ModemManager.service]
  ProcVersionSignature: Ubuntu 5.0.0-13.14-generic 5.0.6
  Uname: Linux 5.0.0-13-generic x86_64
  ApportVersion: 2.20.10-0ubuntu27
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Thu May  2 15:35:58 2019
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2018-05-26 (340 days ago)
  InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: modemmanager
  UpgradeStatus: Upgraded to disco on 2019-04-18 (13 days ago)

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