Px4 firmeware .bin file heads issue

anyone know where can find the heads define of the px4 firmeware bin file .I want add other infos to the bin heads.thanks!

bootloader :
/*
* We refuse to program the first word of the app until the upload is marked
* complete by the host. So if it’s not 0xffffffff, we should try booting it.
*/
if (app_base[0] == 0xffffffff) {
return;
}

/*
 * The second word of the app is the entrypoint; it must point within the
 * flash area (or we have a bad flash).
 */
if (app_base[1] < APP_LOAD_ADDRESS) {
	return;
}