Complexity of emergency-only baseband firmware development

[Denver Gingerich]

On Fri, Mar 10, 2017 at 11:49:53AM -0800, Mychaela Falconia wrote:
> > Eventually
> > I would like to be able to bundle these tools with a phone that runs only
> > free software.
> 
> A phone that runs only free software?  What kind of phone would it be
> hardware-wise: do you plan on building your own hw, or are you trying
> to repurpose/reprogram some existing phone hw units?

It would be great if I could find some existing hardware instead of building my own.  The Neo FreeRunner seems like a good candidate given what you said later (more on that below).

> Not just to Denver but to everyone: please remember that with *ANY*
> libre or FOSS phone goal, the software is the easy part; the hard part
> is the hardware.

I've created (rather unsophisticated) hardware in the past (see http://ossguy.com/ss_usb/ ).  I realize that building a phone is a substantial undertaking so I'd like to avoid that if possible.

> The *only* hardware feature which can be omitted if you wish to limit
> cell functionality to emergency calls only is the SIM socket.  The SIM
> socket I use on the FCDEV3B costs $2.12 in quantity 1 at Digi-Key (or
> down to $1.38 per piece when buying 1000-piece reels), and my opinion
> is that if you omit the SIM socket on your phone in order to
> *artificially* restrict its cellular capabilities to emergency calls
> only, you are being antisocial by artificially hobbling your product
> to suit your particular prejudices.

I would be fine with retaining the SIM socket in whichever solution I eventually end up using.

> > My understanding from being on the list for a while is that the current
> > baseband firmware works for some basic use cases on existing phones,
> 
> Not just for "some basic use cases", but 100% of standard commercial
> GSM+GPRS modem functionality:

My apologies.

> if you have a Neo Freerunner made by
> Openmoko, the Calypso GSM+GPRS modem included in that product provided
> full commercial quality implementation of all standard GSM and GPRS
> functionality with the official firmware those units shipped with, and
> this full functionality is retained without any degradation if you
> replace their original proprietary firmware with FC Magnetite.

I do have a Neo FreeRunner so perhaps that should be my first goal: to run FC Magnetite and see how well it works for me.

> Our Magnetite firmware has not been fully deblobbed yet, but:
> 
> * We have a clear roadmap toward a fully deblobbed version;

Does it seem like a substantial amount of work?  Or is there not much left now?

> 1: Neo Freerunner by Openmoko.  This hw is where the original
>    FreeCalypso project started, and has the best support.  But the
>    Freerunner is not a bare modem or a dumbphone, it also has a Linux
>    application processor that requires very complex software to make
>    it usable as a phone, and the community that once maintained this
>    complex sw is now gone.  Without an active community of developers
>    to maintain that Linux AP software, the Freerunner makes a very
>    poor choice of phone: it is too complex and too power-hungry to
>    serve as a dumbphone substitute, yet it does not really offer
>    anything of practical value that a proper dumbphone can't do, thus
>    it is neither here nor there - "neither fish not meat" as the
>    Russian saying goes.

Would it not still offer wifi support?  If so, then it seems to be a good candidate for my use case.  And I would be unlikely to find a dumbphone that would do wifi anyway.

Of course, as you said, the community is mostly gone at this point.  Bringing that back would be a challenge, but if I was able to work on the FreeRunner software full-time for a while, perhaps I could make that happen.

> if the people who have funded
> the current FCDEV3B effort wish to continue further in this direction,
> we can produce a FreeCalypso modem in a packaged form factor similar
> to SIM900 etc, and the liberated firmware for this mode of operation
> is already here and 100% functional.

That would be an excellent way forward if for some reason the FreeRunner is not suitable.

> > So I'd be curious to know if the emergency-only use case is substantially
> > easier to develop for, or if it's roughly the same complexity as developing
> > for the all-purpose use case, or somewhere in between.
[...]
> In terms of software, the emergency-only use case is more complex
> because you would have to do extra work to remove perfectly good and
> working code for non-emergency functionality.

Thanks for clarifying that.  I have no intention of spending time removing such functionality - it seems fine to leave it in and retain the SIM card slot as discussed.

> I hope my answers clarify things for you a little.

They certainly do!  Thank-you very much.

Denver
http://soprani.ca/