[quote author=Andreas Watterott date=1469616422 link=msg=2858177]
Arduino v1.6.10 has now the latest Atmel toolchain integrated. However the header file, device-specs and avrdude config for the ATmega328PB are missing.
https://www.arduino.cc/en/Main/ReleaseNotes[/quote]
I tried to follow your instructions to get full 328PB support on 1.6.10 on Linux, but when installing from the boards manager (as described at GitHub - watterott/ATmega328PB-Testing: Atmel/Microchip ATmega328PB support for Arduino IDE) I get the following error:
Lo strumento avrdude non è disponibile per il tuo sistema operativo.
which translates to "The avrdude tool is not available for your operating system". This sounds weird, as there seem to be no binaries in the package, as avrdude is actually installed with the IDE.
The manual installation works fine though, I can compile for the 328PB without any issues. I can't test the code as I have no boards yet, though.