634 Novell ZENworks 7.2 Linux Management Administration Guidenovdocx (en) 11 July 2008F.2 Understanding Device Boot Processes in aZENworks Imaging EnvironmentThe following provides a high-level overview of a Linux boot process and how ZENworks 7imaging 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, amodified pxelinux for booting using PXE, or linld.com when using a single diskettewith the CD. If you have a ZENworks partition installed, it uses the lilo program to bootalternately 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 filesystem.Regardless of which boot loader method is used, the main purpose is to set up the initrd fileas a RAM drive, load the Linux kernel into memory, then turn control over to it with anindication to the Linux kernel of where to find initrd.3. The Linux kernel turns control over to linuxrc, for performing initial hardware detection. Whenfinished, 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 orpassed 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 635F.2.1 linuxrcWhen control is turned over to linuxrc, there are several processes it performs to get the systemready 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 beplaced in the /info file (located in the initrd file system), but ZENworks does not normally usethis information.Linuxrc also loads a root file system, which is combined with the initrd file system that is setup 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 PXEPreboot Loader isolinux linld.comLinux Kernel Name /boot/loader/linux /srv/tftp/boot/linuxInitrd Filename /boot/loader/initrd /srv/tftp/boot/initrd
