Novell LINUX ENTERPRISE SERVER 10 SP2 - INSTALLATION AND ADMINISTRATION Installation Manual page 408

remaining part of the boot process. Therefore, the first 512 bytes on the first hard
disk are referred to as the Master Boot Record (MBR). The boot loader then passes
control to the actual operating system, in this case, the Linux kernel. More informa-
tion about GRUB, the Linux boot loader, can be found in Chapter 21, The Boot
Loader (page 405). For a network boot, the BIOS acts as the boot loader. It gets
the image to start from the boot server then starts the system. This is completely
independent of local hard disks.
3. Kernel and initramfs
kernel and an initial RAM–based file system (initramfs) into memory. The contents
of the initramfs can be used by the kernel directly. initramfs contains a small exe-
cutable called init that handles the mounting of the real root file system. If special
hardware drivers are needed before the mass storage can be accessed, they must
be in initramfs. For more information about initramfs, refer to Section 20.1.1,
"initramfs" (page 390). If the system does not have a local hard disk, initramfs must
provide the root file system to the kernel. This can be done with the help of a net-
work block device like iSCSI or SAN, but it is also possible to use NFS as the root
device.
4. init on initramfs
root file system, like providing kernel functionality for the needed file system and
device drivers for mass storage controllers with udev. After the root file system
has been found, it is checked for errors and mounted. If this has been successful,
the initramfs is cleaned and the init program on the root file system is executed.
For more information about init, refer to Section 20.1.2, "init on initramfs"
(page 391). Find more information about udev in Chapter 24, Dynamic Kernel Device
Management with udev (page 463).
5. init
providing different functionality. init is described in Section 20.2, "The init Process"
(page 393).
20.1.1 initramfs
initramfs is a small cpio archive that the kernel can load to a RAM disk. It provides a
minimal Linux environment that enables the execution of programs before the actual
root file system is mounted. This minimal Linux environment is loaded into memory
by BIOS routines and does not have specific hardware requirements other than sufficient
390 Installation and Administration
To pass system control, the boot loader loads both the
This program performs all actions needed to mount the proper
init handles the actual booting of the system through several different levels