I experienced the same issue under Ubuntu 13.04 with a prototype
research device using a Bluetooth SPP module over /dev/rfcomm (like
Roland already pointed out) and this issue probably affects lots of
people working with self-built Bluetooth or cable bound serial port
devices. This is a very bad and non-acceptable behavior of modemmanager
for the following reasons:

1. Things break that used to work before an distribution update. In the
past, unfortunately I do not know the exact version but 11.x should have
worked, things worked. Maybe modemmanager was not probing devices
automatically or was not activated/installed by default. From a user
perspective, there is no easy way to find out why things don't work as
expected anymore. I, for example, had to inspect the memory holding the
incoming bytes on my microcontroller to realize that more bytes arrive
than my application is actually sending. It took me quite a while and it
was really annoying.

2. Devices might behave unusual from one day to the next after an
update, because they receive bytes they do not expect. In the best case,
the devices do not work at all, in the worst case they behave oddly and
might even get damaged or cause damage (robots, control devices... who
knows what's out there)

>From what I read in other bug reports, the developers of modemmanager
favor a blacklist of devices not to probe as the solution to this issue.
I strongly disagree with this solution because it is not working for all
the prototype devices and relies on the idea that every problem has to
occur once and annoy somebody once before it is solved.

-- 
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/490194

Title:
  /sbin/modemmanager is too aggressive managing devices that aren't
  known to be modems

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/modemmanager/+bug/490194/+subscriptions

-- 
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs

Reply via email to