DSS usage

Aleksander Morgado aleksander at aleksander.es
Thu Apr 10 08:27:20 PDT 2014

On Thu, Apr 10, 2014 at 5:10 PM, Dmytro Milinevskyy
<dmilinevskyy at sequans.com> wrote:
> I would like to add few cents to Arnaud's email.
> Is smth preventing modem manager to keep wwan interface up if DSS channels
> are in use? I expect that modem manager is aware of their presence.
> In my opinion the link state of wwan interface should always be "up". If
> there's a need to disable wwan interface the modem manager can flush IP
> address(es) assigned to it and clean the routing table(which normally should
> be done automatically).
> This will eliminate any change to existing kernel drivers.

ModemManager won't be aware of DSS channels, as those will (some day,
when it gets finished) be allocated through the 'mbim-proxy' setup in
libmbim, not through ModemManager.

Also, as a side note, bringing the iface up and keeping it that way
will be a task of NetworkManager, not ModemManager.

I have mixed feelings in to whether this is a task of the kernel (the
one which enables VLANs for the actual DSS channels in the net
interface) or a task for userspace (the one actually requesting to
create the DSS channels). NetworkManager will definitely not know
whether a DSS channel is ongoing, unless we e.g. link libmbim-glib to
it and we maintain the list of DSS channels setup in the mbim-proxy.
It's kind of nasty to do that, though... having it managed by the
kernel, if easy, would be more clear - at least for userspace, of


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