Bug#877024: modemmanager should ask before messing with serial ports

[Aleksander Morgado <aleksander@aleksander.es>]

Hey Sam,

> It looks like there hasn't been much traffic on this issue in the last
> couple of weeks.
>

Well, I moved the discussion to the ModemManager mailing list and it's
already been discussed there among MM developers.

> My analysis is that the key technical point here is whether it's
> acceptable to treat unknown devices as possible modems.
>
> It sounds like:
>
> 1) We don't have a good white list of modems.
>
> 2)  We don't have an adequate blacklist of modems.  Ian argues we never
> will have an adequate blacklist of modems.
>

There's a third approach, which is what we've been discussing in the
mailing list as a possible good compromise. We are going to update
ModemManager with a new command line option that will enable some
heuristics to try to guess whether a given set of ports correspond to
a modem or not (e.g. based on kernel driver, usb layout and so on).
Ideally, this means no blacklist would be needed, and ModemManager
would only probe TTYs that are definitely modems. The drawback is that
ModemManager won't automatically probe modems that would fall out of
the heuristics, but given that most new modems come with network
devices, the amount of devices left out should be minimal.

The new command line option will enable the new heuristics, and if the
command line option not given, the old behavior with the blacklist
will be kept. I'm assuming Debian could make use of the new command
line option by default, and that would solve this issue.

> In going forward, I think it is important to consider that
> Modemmanager's needs and Debian's needs may be different here.
> In the case of Modemmanager as an upstream project, it may be desirable
> to give the best experience for users who do have modems.
> However, for Debian and for the Technical committee, we need to consider
> what experience we want to give all our users and as a result value
> damage caused by false positives more highly than the upstream project
> might.

Would the new approach satisfy Debian's needs?

-- 
Aleksander
https://aleksander.es