Part II Booting a Linux system #

Booting a Linux system involves different components and tasks. After a firmware and hardware initialization process, which depends on the machine's architecture, the kernel is started by means of the boot loader GRUB 2. After this point, the boot process is completely controlled by the operating system and handled by systemd. systemd provides a set of “targets” that boot configurations for everyday usage, maintenance or emergencies.

UEFI (Unified Extensible Firmware Interface) is the interface between the firmware that comes with the system hardware, all the hardware components of the system, and the operating system.

This chapter describes how to configure GRUB 2, the boot loader used in SUSE® Linux Enterprise Server. It is the successor to the traditional GRUB boot loader—now called “GRUB Legacy”. GRUB 2 has been the default boot loader in SUSE® Linux Enterprise Server since version 12. A YaST module is available for configuring the most important settings. The boot procedure as a whole is outlined in Chapter 12, Introduction to the boot process. For details on Secure Boot support for UEFI machines, see Chapter 13, UEFI (Unified Extensible Firmware Interface).

systemd is responsible for initializing the system, and it has the process ID 1. systemd is started directly by the kernel and resists signal 9, which normally terminates processes. All other programs are either started directly by systemd or by one of its child processes. systemd is a replacement f…