Installation guide

Chapter 30. Configuring ELILO
ELILO is the boot loader used on EFI-based systems, notably Itanium® . Similar to the GRUB, the
boot loader on x86 and x86-64 systems, ELILO allows the user to select which installed kernel to
load during the system boot sequence. ELILO also allows the user to pass arguments to the kernel.
The ELILO configuration file, which is located in the EFI boot partition and symbolically linked to
/etc/elilo.conf, contains a list of global options and image stanzas. When you install the
kernel-xen RPM, a post install script adds the appropriate image stanza to the elilo.conf.
Important
This section on ELILO is for systems running the Xen kernel on the Intel Itanium architecture.
The ELILO configuration file has two sections:
Global options that affect the behavior of ELILO and all the entries. Typically there is no need to
change these from the default values.
Image stanzas that define a boot selection along with associated options.
Here is a sample image stanza in elilo.conf:
image=vmlinuz-2.6.18-92.el5xen
vmm=xen.gz-2.6.18-92.el5
label=linux
initrd=initrd-2.6.18-92.el5xen.img
read-only
root=/dev/VolGroup00/rhel5_2
append="-- rhgb quiet"
The image parameter indicates the following lines apply to a single boot selection. This stanza
defines a hypervisor (vmm), initrd, and command line arguments (read-only, root and append)
to the hypervisor and kernel. When ELILO is loaded during the boot sequence, the image is labeled
linux.
ELILO translates read-only to the kernel command line option ro which causes the root file system
to be mounted read-only until the initscripts mount the root drive as read-write. ELILO copies the
"root" line to the kernel command line. These are merged with the "append" line to build a complete
command line:
"-- root=/dev/VolGroup00/rhel5_2 ro rhgb quiet"
The -- symbols delimit hypervisor and kernel arguments. The hypervisor arguments come first, then
the -- delimiter, followed by the kernel arguments. The hypervisor does not usually have any
arguments.
Note
ELILO passes the entire command line to the hypervisor. The hypervisor divides the content
and passes the kernel options to the kernel.
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