Boot linux from u-boot

Linux command line arg

bootargs

 setenv fdtaddr <ftd_ddr_address>;
 fatload <interface> <device>:<partation> ${fdtaddr} <dtb-file>

For Example:

copy board.dtb from mmc device 0, partation 1 to ddr address 0x88000000

 setenv fdtaddr 0x88000000;
 fatload mmc 0:1 ${fdtaddr} board.dtb

 setenv dtboaddr <dtbo_ddr_address>;
 fatload <interface> <device>:<partation> ${dtboaddr} <dtbo-file>;
 fdt apply ${dtboaddr};

For Example:

copy someoverlay.dtbo from mmc device 0, partation 1 to ddr address 0x89000000 and then appy overlay

 setenv dtboaddr 0x89000000;
 fatload mmc 0:1 ${dtboaddr} someoverlay.dtbo;
 fdt apply ${dtboaddr};

NOTE: 0x89000000 will be change based on your platform

 set ipaddr <own-ip-address>
 set serverip <host_pc_ip_address>

 tftp ${ddr_addr} ${serverip}:<file-to-download>;