Aleksander Morgado writes ("Bug#877024: modemmanager should ask before messing
with serial ports"):
> [Ian Jackson:]
> > Many such modems present as USB serial devices, eg ttyACM or ttyUSB.
> > Consequently, modemmanager has the ability to open serial ports and
> > probe them to see if they respond to Hayes-style AT commands. That
> > functionality is currently triggered automatically by default, even
> > for USB serial ports whose USB device IDs are unknown to modemmanager,
> > or whose device IDs correspond to generic USB-to-serial adapters.
...
> A clarification here, ModemManager doesn't automatically probe
> usb-to-serial converters, those are "greylisted" so that they're
> only probed on "manual scans". Of course, the vid:pid needs to be
> known to MM and in the greylist, for this to happen.
Thanks for the clarification.
The greylist is nevertheless never going to be complete. My initial
message in #877024 lists some of the consequences, many of which
actually occurred with generic USB-to-serial adapters (or generic
USB-to-serial chips).
Ian.
