[Replicant] Wanting a freedom phone
Denis 'GNUtoo' Carikli
GNUtoo at cyberdimension.org
Mon Sep 6 22:21:37 UTC 2021
On Thu, 26 Aug 2021 20:27:07 +0200
"W. Kosior" <koszko at koszko.org> wrote:
> > > True, although even Replicant phones are not 100% free. Perhaps
> > > you've already heard that no libre cellular modem exists.
> > A free firmware (OsmocomBB) exist, but it's for very old mobile
> > phones (that aren't smartphones) and the Openmoko Smartphones
> > modem. The OpenMoko part that runs GNU/Linux only has 128M of RAM,
> > and there is (almost) no upstream kernel support for it.
> Also, the modem still needs some low-level nonfree firmware beyond
> what OsmocomBB provides and OsmocomBB has never actually been
> certified for use on carrier networks.
As far as I understand it's a DSP rom that can be patched by loading a
firmware in a dedicated sram.
Some free software patches exist for specific tasks but they probably
cannot implement everything because if I recall well the sram is
smaller than the rom.
> There was also an approach to replace the low-level nonfree part with
> a software-defined radio. It supposedly works, although isn't suitable
> for use with a phone and is also not legal to use on carrier networks.
We'd need to do some legal research to know if it's legal or not
and/or in which conditions it can be legal.
The laws and regulations I heard about (in Germany and EU mostly) only
covered the sale of devices. I didn't ear (yet) about specific laws
regulating the use of non-certified software on radio networks
like cellular or WiFi networks.
Though it's obvious that it's a really bad idea to disrupt networks as
people might rely on them for important things like calling medical
emergency services for instance.
For running a cellular network however, you need a license (like a test
license or a commercial license) and it's also really easy to mess up
and disrupt networks accidentally if the clocks you use aren't precise
enough. People typically clocks that are derived from the GPS time to
run small scale networks.
> In this case, however, it seems we have to first tackle the technical
> obstacles to be able to do anything about legal ones.
There are various ways to avoid the legal obstacles. For instance you
could transmit in cables and attenuate the signal as well to make sure
it doesn't go outside the cables. This could probably enable to work on
modems almost anywhere in the world.
As for the technical part, not all SDRs can do all the cellular network
protocol as there are often hardware and software requirements for
that. Harald Welte did a good talk on that at the last CCC Camp.
For the freedom part, several SDR have free firmwares, but I didn't
check if the "source code" / hardware description language could be
"compiled"/syntetized with the free FPGA toolchain(s).
A good approach to make use of all that would probably be to have
modular phones that would boot with free software and where you could
replace or remove the WiFi and modems somehow.
> > > Likewise, I never heard of any phone with free wi-fi.
> > I think reverse engineering Realteck or Broadcom firmwares would be
> > a good idea to fix that:
> > - Some Realtek firmwares have been published as hexadecimal numbers
> > in source code covered by the GPL. So if we can somehow reconstruct
> > the source code from the 8051 assembler, it could yield some free
> > software firmware.
> > - Many Broadcom WiFi chips have a rom, and the firmware is a patch
> > on top of that rom. There are (hopefully free software) projects
> > to develop patches for that rom.
> It might also make sense to contribute to PINE64's REing initiative,
> even though the targetted chip is of neither of those 2 brands.
Indeed. Any WiFi chip for mobile devices that work with only free
software would be great. If we get one, future device manufacturers
could use it at least.
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