The Beagleboard xM-rev C requires the following patch. This is upstream, so an x-loader refresh should take care of it. http://gitorious.org/x-loader/x-loader/commit/2efa178acd56d83c86210b5934895cfb9ea62125
Updating now
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=93f60471b504802417353595b8730c58272b139e