Novell ZENWORKS LINUX MANAGEMENT 7.3 IR2, Administration Manual

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648 Novell ZENworks 7.3 Linux Management Administration Guide
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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:
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:
Š
Section F.2.1, “linuxrc,” on page 648
Š Section F.2.2, “zenworks.s,” on page 649
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
.
Files When booting from a CD When booting from PXE
Preboot Loader
isolinux linld.com
Linux Kernel Name /boot/loader/linux /srv/tftp/boot/linux
Initrd Filename
/boot/loader/initrd /srv/tftp/boot/initrd