DSS usage

Dan Williams dcbw at redhat.com
Thu Apr 10 08:59:08 PDT 2014

On Thu, 2014-04-10 at 17:49 +0200, Dmytro Milinevskyy wrote:
> Thanks Aleksander for the quick response.
> I tend to agree that DSS data should not be forwarded via VLAN interfaces as it's not a natural approach for such data pipes.
> Also userspace has to deal with bogus MAC address inserted by mbim driver.
> My request to handle this in userspace was based on fear that it would be much harder to integrate(or convince the vendors to integrate) modifications into usbnet and mbim kernel drivers.
> I'm afraid that it would take ages to hit the upstream kernel and finally the end distros.
> Of course as the long term solution a DSS channel should be visible as a character device. 

If there are known/quasi-standardized DSS protocols that eventually show
up, I think libmbim or something else should probably speak those
protocols too.  I guess we'll have to see how this all falls out when
DSS starts showing up (if it hasn't already?).


> regards,
> ~ Dmytro
> ----- Original Message -----
> > 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
> > course...
> > 
> > --
> > Aleksander
> > https://aleksander.es
> > 
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