Overview
Power On Self Test (POST) is the first task which verifies the hardware functionality of various modules during boot-up. Based on the criticality of the test, the selftest module decides whether to go ahead with the boot-up sequence of a particular subsystem or interface during a POST failure.
POST comprises of the following:
Front-end Port Loopback tests
This is to verify the physical port front-end interface.
These tests check if a particular interface can function properly. A test failure would mean that the particular interface is marked as "Failed" and thus it would become unavailable for use.
This test is run when "no fastboot" is configured.