Understanding Device Boot Processes In A Zenworks Imaging Environment; Linuxrc; F.2.1 Linuxrc - Novell ZENWORKS LINUX MANAGEMENT 7.2 IR2 - ADMINISTRATION GUIDE 09-25-2008 Administration Manual

F.2 Understanding Device Boot Processes in a
ZENworks Imaging Environment
The following provides a high-level overview of a Linux boot process and how ZENworks 7
imaging affects it:
1. A boot loader program loads the Linux kernel and initrd (initial RAM drive) into memory.
The SLES-based imaging distribution uses isolinux as the boot loader for imaging CDs, a
modified pxelinux for booting using PXE, or linld.com when using a single diskette
with the CD. If you have a ZENworks partition installed, it uses the lilo program to boot
alternately between the ZENworks partition and the installed operating system.
Following are the filenames and paths:
Files
Preboot Loader
Linux Kernel Name
Initrd Filename
2. The Linux kernel starts running, does some device driver setup, then mounts the initrd file
system.
Regardless of which boot loader method is used, the main purpose is to set up the initrd file
as a RAM drive, load the Linux kernel into memory, then turn control over to it with an
indication to the Linux kernel of where to find initrd.
3. The Linux kernel turns control over to linuxrc, for performing initial hardware detection. When
finished, control is returned to the Linux kernel.
4. The Linux kernel starts a background process (/sbin/init).
After control is passed to the linuxrc program, control is never returned to the Linux kernel or
passed on to the init process.
For more information on linuxrc and zenworks.s, review the following sections:
Section F.2.1, "linuxrc," on page 634
Section F.2.2, "zenworks.s," on page 635

F.2.1 linuxrc

When control is turned over to linuxrc, there are several processes it performs to get the system
ready for the imaging process. Linuxrc is initially configured from the /linuxrc.config file,
which is located in the initrd file system. Additional configuration information for linuxrc can be
placed in the /info file (located in the initrd file system), but ZENworks does not normally use
this information.
Linuxrc also loads a root file system, which is combined with the initrd file system that is set
up by the boot loader. The root file system is located on an imaging CD as the file /boot/root.
For PXE booting, the root file system is stored on the ZENworks imaging server as /srv/tftp/
boot/root.
634 Novell ZENworks 7.2 Linux Management Administration Guide
When booting from a CD
isolinux
/boot/loader/linux
/boot/loader/initrd
When booting from PXE
linld.com
/srv/tftp/boot/linux
/srv/tftp/boot/initrd