Understanding the boot process – BIOS and UEFI booting
Computers have hardware-embedded software controllers, also called firmware, that let you manage the very lowest layers of the hardware. This firmware performs the first recognition of what hardware is available in the system and what hardware features are enabled (such as pre-boot network execution, also called PXE).
In the architecture known as PC (short for Personal Computer), also referred to as x86, which Intel and IBM popularized, the embedded firmware is referred to as Basic Input and Output System (BIOS).
The BIOS boot process, with Linux, takes the following steps:
- The machine is powered on, and the BIOS firmware is loaded.
- The firmware initializes devices such as the keyboard, mouse, storage, and other peripherals.
- The firmware reads the configuration, including the boot order, specifying which storage device is the one to continue the boot process with.
- Once the storage device has been...