Here is the list of boards supported in the F21 beta:

ls /usr/share/uboot/ A10-OLinuXino-Lime arndale Cubieboard Mele_A1000 panda snowball wandboard_quad A10s-OLinuXino-M Bananapi Cubieboard2 Mele_A1000G paz00 trimslice wandboard_solo A13-OLinuXino beagle Cubietruck Mini-X riotboard udoo_quad A13-OLinuXinoM beaglebone highbank Mini-X-1Gb smdkv310 uevm A20-OLinuXino_MICRO cm_fx6 jetson-tk1 origen snow wandboard_dl