Booting and initializing a UNIX system can challenge even an experienced system administrator. This chapter gives a short overview of the SUSE LINUX boot concept. The current implementation is compatible with the System Initialization section of the LSB specification (Version 1.3.x). Refer to Linux Standard Base (LSB) for more information about LSB.
The kernel takes control of the system's hardware as soon as the simple message "Uncompressing Linux..." is printed on screen. The kernel checks and sets the console (the BIOS registers of graphics cards and the screen output format), reads BIOS settings, and initializes basic hardware interfaces. Next, the drivers, which are part of the kernel, probe existing hardware and initialize it accordingly. After checking the partitions and mounting the root file system, the kernel starts init, which boots (Unix jargon) the main system with all its programs and configurations. The kernel controls the entire system, managing hardware access and allocating CPU time and memory to programs.