Any brave dive computer download testers out there?

Jef Driesen jef at
Thu Apr 26 07:44:13 PDT 2018

On 2018-04-25 22:12, Linus Torvalds wrote:
> On Wed, Apr 25, 2018 at 11:51 AM, Dirk Hohndel <dirk at> 
> wrote:
>> I have a Petrel (single stack BT) and Petrel 2 (dual stack) and will 
>> test
>> those over lunch today. I'll try to test Mac and Android 
>> (embarrassingly,
>> I currently don't have a Linux laptop with working BLE...)
> Note that the magic channel/port number thing is Linux 
> desktop-specific:
>   #if defined(Q_OS_LINUX) && !defined(Q_OS_ANDROID)
> And it was literally the Petrel 2 that triggered that "try channel 5".
> I have no idea how that is supposed to work, or what the crazy rules
> about rfcomm ports even -are-. I'm just looking at the code, and going
> "eww".
> Also note that on Linux and Windows, we could just use the
> libdivecomputer bluetooth backend that just uses the raw socket.
> Also, Jef just uses port 0 for everything.
> So the whole "port/channel" thing may be entirely pointless.

In the libdivecomputer rfcomm implementation, port 0 means 
auto-detection. On linux it does an SDP discovery internally to find the 
correct rfcomm port number, and on Windows it uses the rfcomm uuid 
instead of the port number. That way, it should always just work. And on 
the hardware I tested, it does indeed.

I also don't know the exact details on how these port numbers are 
assigned. I guess it depends on the dive computer firmware and/or its 
bluetooth stack. The valid range for rfcomm ports is 1-30 if I remember 

The Petrel is certainly not the only one which is using a different port 
number. I'm currently testing the and it seems to use 
port 6.


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