ubuntu-phone team mailing list archive

[Simon Fels <simon.fels@xxxxxxxxxxxxx>]

Hey everyone,

as some might know we're currently in the transition period to BlueZ 5.x 
on Ubuntu Touch. Until now we're still using version 4.101 which dates 
back to 2012. BlueZ 5 is a rework of the former version with a changed 
DBus API and a lot of improvements/refactorings across the whole stack. 
Overall this will bring us a more stable and reliable bluetooth stack 
and also some new features like Low Energy support.

The reason why we never did the switch until now (desktop waited for us 
a long time but did the switch finally with wily) was that we have 
pretty dated kernels on all our supported Touch devices (mako 3.4, flo 
3.4, krillin 3.4, arale 3.10). Those ship with an older variant of the 
kernel side bluetooth stack which lacks features, bug fixes, 
improvements, etc. Upstream says we should use at least 3.13.

We tried different approaches but now found a way which works for all 
devices the same way with just a minimal amount of work. Basically we 
will use the kernel backports project (see [1]) to bring a newer version 
of the kernel side bluetooth stack in. With this we just have one patch 
we apply to all our kernel trees plus some small tree specific changes 
and get all features and bug fixes from a latest kernel release which is 
4.2 at the moment.

However this was just the first step of the journey to BlueZ 5. The next 
step is to update all userland components which is what we work on at 
the moment.

To get some first feedback of the kernel side work we uploaded new 
kernels for the Nexus 4 (mako) and Nexus 7 2013 (flo) which includes the 
new kernel side bluetooth stack. They should come to your devices if 
you're using the rc-proposed channels. Basically there should be no 
regressions as BlueZ 4.x still works with the newer stack too. However 
if you discover anything which looks like a regression or see any 
crashes on the kernel please don't hesitate to report those!

If someone is interested in the kernel patches, you will find them on 
[2] for mako and [3] for flo.

As soon as there is a silo ready to be tested with the userland rework I 
will send another update this way.

regards,
Simon

[1]: https://backports.wiki.kernel.org/index.php/Main_Page
[2]: http://kernel.ubuntu.com/git/ubuntu/ubuntu-vivid.git/log/?h=mako
[3]: http://kernel.ubuntu.com/git/ubuntu/ubuntu-vivid.git/log/?h=flo