Why SOC boots from FPGA?

[Altera_Forum]

The SOC preloader can be loaded from FPGA memory. After the pre-loader is run, the software will be loaded from the SD card. So why do we have such an option if the real application will be loaded from the SD Card?  

In what situation will anyone need this?  Thanks  

[Altera_Forum]

you may think about production of some boards, where no sd-card is available, but an eMMC which is not pre-programmable...

[Altera_Forum]

This enables secure boot support at CV where FPGA image will be validated through AES engine :) 

By doing this, the executed Preloader is trusted.