I am wondering if somebody already tried or know how to use eclipse debugger on samr21-xpro. I followed the eclipse tutorial for RIOT but it stops at this part and before spending long hours configuring eclipse if somebody already did it, it would be nice to know how.
since I don't use Eclipse or the board I can't tell for sure, but the board
gets debugged via openocd and so  looks promising to me. If you have success
you're welcome to extend the existing documentation with your findings...
Thank you very much Hinnerk for your answer. I am currently working to set Eclipse Luna working on Ubuntu for Sam R21. When I'll succeed, I will add to the documentation the implementation of this specific board.