1) nfs
I burn the uboot to board by mfgtool, then starting the kernel by nfs, when the board boot up, I set a) ipaddr and b)serverip, then I set the c)"setenv nfsroot /home/usuario/fsl-release-bsp/buildimx6q/tmp/work/imx6qsabresd-poky-linux-gnueabi/fsl-image-gui/1.0-r0/rootfs", this is sample, you need choose correct folder for yours, this is for imx6q, d) set the mdt file,then run the netboot.
2) program uboot to the qspi, then boot from SD card
3) change the mfgtool to program uboot, kernel to the qspi
attched the ucl2.xml
setenv bootcmd 'run bootargsset; sf probe; sf read ${loadaddr} 0xA00000 0x600000; sf read ${fdt_addr} 0x800000 0x10000; bootz ${loadaddr} - ${fdt_addr}'
