[Development] Linux release binaries too old

[Blasche Alexander]

> -----Original Message-----
> From: development-bounces+alexander.blasche=digia.com at qt-project.org
> [mailto:development-bounces+alexander.blasche=digia.com at qt-project.org]
> On Behalf Of Alejandro Exojo


> How feasable is to backport a newer BlueZ to that old distro, on the machines
> that build the binaries? I managed to do a quick and dirty BlueZ 5 backport to
> Debian stable quite easily (where "easy" means I got the backported kernel
> already on the distro, so that's done). I can give it a try if needed, since
> BlueZ 4 should be easier. I don't remember any kernel requirements.

The Bt LE feature requires 3.5 kernel or above. My guess would be that a kernel below that version (although maybe Bluez support it) won't enable the feature.

In theory we should be able to deploy newer headers to old 11.10. The dependency is "just" a compile time one. After that it's just interaction between Qt and the kernel.
 
> > Bluetooth requires the newer headers only at build time. I tested binaries
> > on 12.04 by faking the new symbols and it still seemed to work.
> >
> > The question is how many old distros do we leave behind? Bluez 4.101 was
> > released in June 2012. If distros update Qt they are likely to recompile
> > anyway.
> 
> Release dates are a bit misleading here. ;-)
> 
> Compare the popularity of Qt4 vs Qt5 applications on distributions. With BlueZ
> is worse, since is a complete rewrite of the API. Even the most recent Ubuntu
> is still on BlueZ 4.

Bluez 4 or 5 doesn't matter. Qt 5.4 supports both and uses whichever Bluez version it can find at runtime.