Hi Nick,

there is some news about it:
I have found a custom Lineage ROM which supports BLE peripheal mode (beacons) 
for i9300 and it seems to work
like a charm with and CCTG [1] which includes 'microG'.

Both, Replicant 6 and these ROMs use Linux 3.0.101, hence it seems to be 
possible to create a patch for the
Bluetooth stack and perhaps use another firmware to get that working with 
Replicant in a free software compatible
manner.
Let me know what you think.

Are you able to compare whether the
firmware in your working i9305 is the same as the one that you would
have used with replicant, [...]

Sorry for leaving this unanswered. I am trying to have a look into this the 
next days ^^

[1] https://codeberg.org/corona-contact-tracing-germany/cwa-android


Reagrds,
doak



On 20.10.20 14:25, Nick wrote:
Hi doak,

Thanks very much for your response, your questions are things that I
hadn't generally thought of!

Did you check if your device actually sends BLE beacons?

I did not! I checked that it received beacons, and it does, so I
naively assumed therefore that all would be perfect.

At the beginning of the german tracing app I configured an i9305 (S3 LTE) with 
Lineage, OpenGApps and the
app (this not free SW) and *it seemed* to work but did **not**!
Reason was that BLE beacons could be received, but not sended. I checked that 
with 'nRF Connect' which is
able to trace bluetooth packets and shows additional information also for BLE 
beacons. Furthermore it is
able to list device capabilities. In my case 'Periphal mode' was not availabble.
At the end I have tried dozen different (questionable) ROMs till I found one 
which in fact supports pheriphal
mode and thus was able to send BLE beacons.

I found an apk for the proprietary 'nRF Connect' app
(no.nordicsemi.android.mcp) online and installed it. It does indeed
list 'Peripheral mode' as not supported on this device (basic
Bluetooth Low Energy is, though). I only have one other android
device, which has very old software on, and I couldn't get nRF
Connect to install, so I couldn't test whether my phone was indeed
successfully sending BLE beacons, but presumably not. There is more
information about this "peripheral mode" being essential to the
sending aspect of exposure notifications at [0].

There is still some utility in running the app in "receive only"
mode, as I would still be alerted if someone I was in contact with
sufficiently closely tested positive and could have been infectious
at the time. But obviously it's nicer to be able to return the
favour.

I am still not sure if the signal strength is as strong as it should be. My gut 
feeling is that it is too
weak which would make the estimated risk wrong and thus useless.

I have no idea how one could test such a thing. It does seem to be
collecting lots of IDs when I've been out, more than I would expect
if it was weaker than it should be. But I have no way of knowing
either.

Furthermore I at least know that the i9305 is able to send them if used 
kernel/firmware supports it. Dunni
about i9300.

That is interesting indeed. I wonder what would be required of
replicant to support it. Are you able to compare whether the
firmware in your working i9305 is the same as the one that you would
have used with replicant, presumably that listed in
i9305-fwinfo/bluetooth.txt from
https://code.fossencdi.org/firmwares_nonfree.git ? If it is the
same, then at least we know that it's likely to be a kernel, rather
than firmware, issue. And if not, then potentially finding some
newer firmware could be enough to fix it.

Thanks again,

Nick

0: https://github.com/corona-warn-app/cwa-app-android/issues/688


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