Linux ModemManager Strikes Back

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PaulStoffregen

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Looks like ModemManager is again interfering with Teensy on Ubuntu 18.04. Seems Ubuntu recently changed MM's default filter policy to "strict", which causes it to ignore some udev tags. :(

I've updated the 49-teensy.rules file with another tag to hopefully keep MM from messing with Teensy.

https://www.pjrc.com/teensy/49-teensy.rules

To check which filter policy ModemManager is using, run this command:

systemctl status ModemManager | grep filter-policy

If you get nothing, that's a pretty good sign you don't have ModemManager. Running without "| grep filter-policy" can confirm.
 
Well, that's one less unexplained phenomenon to workaround.

I noticed, I figured it was something low level I did on my system .
 
Did the new udev rules fully fix the problems on your machine?

It seems to work here on my Ubuntu 18.04 system, though I do still seem some stuff in syslog that ModemManager is taking notice of Teensy.
 
Well, I haven't copied the new rules in (yet). Instead I removed ModemManager.

It was also keeping a USBTinyISP from working correctly.
 
Probably a good idea to get the new udev rules anyway. ModemManager always seems to have a way of coming back to cause more trouble.
 
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