Autoinitializing variables at run time is the default method of autoinitialization. To use this method, invoke the linker with the --rom_model option.
Using this method, the .cinit section is loaded into memory along with all the other initialized sections. The linker defines a special symbol called cinit that points to the beginning of the initialization tables in memory. When the program begins running, the C boot routine copies data from the tables (pointed to by .cinit) into the specified variables in the .bss section. This allows initialization data to be stored in slow non-volatile memory and copied to fast memory each time the program is reset.
Figure 3-2 illustrates autoinitialization at run time. Use this method in any system where your application runs from code burned into slow memory or needs to survive a reset.