Firmware Tasks on Chrome OS - lalilulelulz/Chromium-OS-Coreboot GitHub Wiki

The firmware sets up the basic peripherals such as the keyboard, display, mass storage, security chip (TPM), and SPI flash for its own use while it runs the steps to set up the machine. In Chrome OS, the firmware can be updated, so the system first checks whether an update exists and, if so, it loads the update and jumps to execute it. In normal cases, the OS is available and is loaded and started. If a problem exists (for example, the OS is corrupt), the firmware enters recovery mode, which allows the user to insert media with a new OS. In developer mode, users can bypass Chrome OS security, or even the entire OS.