I answered my own question by a little searching on the wiki - according to github.com/RIOT-OS/RIOT/wiki/Board%3A-Samr21-xpro I should use GNU Tools for ARM Embedded Processors toolchain.
> On Feb 19, 2015, at 9:52 PM 2/19/15, Ralph Droms (rdroms) <rdr...@cisco.com> > wrote: > > What's the recommended toolchain for the SAMR21-XPRO board? > > - Ralph > > _______________________________________________ > devel mailing list > devel@riot-os.org > http://lists.riot-os.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@riot-os.org http://lists.riot-os.org/mailman/listinfo/devel