Start up Code Flow of PX4

Hello Experts,

I am newbee here. I am trying to understand the build process and startup code flow of PX4 in baremetal and Posix environment.

Example:
PX4 Banner print during startup
File where the boot code originates
Driver initialization
RTOS Initialization
Flow of Sensor to Control Loops to Actuators
ROMFS internal flow

Thanks
Satz