Friends,as it turns out , there isn't much to the boot process : A boot loader finds the kernel image on the disk , loads it into memory , and starts it .
The kernel initializes the devices and its drivers .
The kernel mounts the root filesystem .
The kernel starts a program called init .
init sets the rest of the processes in motion .
The last processes that init starts as part of the boot sequence allow you to log in .
Identifying each stage of the boot process is invaluable in fixing boot problems and understanding the system as a whole . To start , zero in on the boot loader , which is the initial screen or prompt you get after the computer does its power-on self-test , asking which operating system to run . After you make a choice , the boot loader runs the Linux kernel , handing control of the system to the kernel .
There is a detailed discussion of the kernel elsewhere in this book from which this article is excerpted . This article covers the kernel initialization stage , the stage when the kernel prints a bunch of messages about the hardware present on the system . The kernel starts init just after it displays a message proclaiming that the kernel has mounted the root filesystem :
VFS : Mounted root ( ext2 filesystem ) readonly .
Soon after , you will see a message about init starting , followed by system service startup messages , and finally you get a login prompt of some sort .
On Red Hat Linux , the init note is especially obvious , because it "welcomes" you to "Red Hat Linux ." All messages thereafter show success or failure in brackets at the right-hand side of the screen .
Most of this chapter deals with init , because it is the part of the