In addition to the standard argc and argv values passed into every process (and envp for environment variables on Unix systems), ELF based systems also include an "auxiliary vector" array which contains a number of useful values to help a process bootstrap. This includes information like processor capabilities, the location of the kernel entry point, system page size, system timer information, user information and a platform string.

You can take a look yourself by running `LD_SHOW_AUXV=1 /bin/true`