Where do I find the source code for the preloader?

I need to build the preloader, but I don’t know where to get the source files. Anyone know?

The Preloader source code is created automatically by the Preloader Generator, in the folder specified in the options. See instructions on how to build the Preloader here: Generating and Compiling Preloader for Cyclone V GSRD 14.1 as an example.

Also take a look at the SoC EDS User Guide for reference information for Preloader and Preloader Generator.