Re: Preventing modem-manager from accessing specific serial ports?

[Aleksander Morgado <aleksander lanedo com>]

On 24/10/13 04:37, Volker Kuhlmann wrote:
> > > http://cgit.freedesktop.org/ModemManager/ModemManager/tree/src/77-mm-usb-device-blacklist.rules
> Thank you very much Dan, adding ID_MM_DEVICE_IGNORE is trivial once one
> knows that is the trick to use.
>
> Are there *any* modems using any of the FTDI USB/serial converters? Or
> does MM handle the old serial port modems too? Because if not, modem
> manager should perhaps be shipped with a blacklist rule for those
> because it can never do any good with them.

MM supports plain RS232 modems (e.g. some Cinterion ones or Iridium
satellite modems).

In MM 0.6.x we had a blacklist for serial devices which are definitely
not modems. In this list we (upstream) didn't include USB<->RS232
adapters, although several distributions then added those in the
blacklist when packaging (therefore removing support for RS232 modems
connected via USB<->RS232 adapters).

To solve this issue and avoid having distros ship additional blacklist
rules, in MM 1.x we added an additional 'greylist', so that we have:
 * a blacklist for serial devices which are definitely not modems (as we
had in 0.6.x upstream)
 * a greylist for USB<->RS232 adapters, as they may have a RS232 modem
behind.

In this setup, MM will never probe the blacklisted ones, and will only
probe the greylisted ones if a manual Scan() is requested (i.e. never
automatically). Setups using MM with a RS232 modem will anyway need a
periodic explicit Scan() to detect whether there is a modem in the
serial port (both with platform ports and for USB<->RS232 adapters), so
applying the greylist only for this case is actually appropriate.

-- 
Aleksander