By default, G28M Zynq-7020 platform supports QSPI as boot device. Switching to SD boot requires hardware modifications.
To manually load the bit-stream, please copy the system.bit file to the SD card and execute the following commands in U-Boot before loading the kernel images in PL22.2 binaries.
fpga info 0
load mmc 0:1 0x1000000 system.bit
fpga loadb 0 0x1000000 0x400000
For further inquiries, please get in touch with mktg@iwave-global.com
Please find the detailed G28M product information in the below link,