Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Mail Systems
Eclipse Documentation

How To Guides
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Problem Solutions
Privacy Policy




Red Hat Enterprise Linux 9 Essentials Book now available.

Purchase a copy of Red Hat Enterprise Linux 9 (RHEL 9) Essentials

Red Hat Enterprise Linux 9 Essentials Print and eBook (PDF) editions contain 34 chapters and 298 pages

Preview Book

Chapter 22. Configuring GRUB

The GNU Grand Unified Boot Loader(GRUB) is a program which enables the user to select which installed operating system or kernel to load at system boot time. It also allows the user to pass arguments to the kernel. The GRUB configuration file (located in /boot/grub/grub.conf) is used to create a list of operating systems to boot in GRUB's menu interface. When you install the kernel-xen RPM, a post script adds kernel-xen entries to the GRUB configuration file. You can edit the grub.conf file and enable the following GRUB parameter.
title Red Hat Enterprise Linux Server (2.6.18-3.el5xen)
root (hd0,0)
	kernel  /xen.gz.-2.6.18-3.el5
	module  /vmlinuz-2.6..18-3.el5xen ro root=/dev/VolGroup00/LogVol00  rhgb quiet
	module  /initrd-2.6.18-3. el5xenxen.img
If you set your Linux grub entries to reflect this example, the boot loader loads the hypervisor, initrd image, and Linux kernel. Since the kernel entry is on top of the other entries, the kernel loads into memory first. The boot loader sends, and receives, command line arguments to and from the hypervisor and Linux kernel. This example entry shows how you would restrict the Dom0 linux kernel memory to 800 MB.
title Red Hat Enterprise Linux Server (2.6.18-3.el5xen)
root (hd0,0)
	kernel  /xen.gz.-2.6.18-3.el5 dom0_mem=800M
	module  /vmlinuz-2.6..18-3.el5xen ro root=/dev/VolGroup00/LogVol00  rhgb quiet
	module  /initrd-2.6.18-3. el5xenxen.img
You can use these GRUB parameters to configure the Virtualization hypervisor:
This limits the amount of memory that is available to the hypervisor kernel.
com1=115200, 8n1
This enables the first serial port in the system to act as serial console (com2 is assigned for the next port, and so on...).
This limits the memory available for the hypervisor.
This limits the amount of CPUs visible to domain0.
This switches the ACPI hypervisor to the hypervisor and domain0. The ACPI parameter options include:
/*   ****  Linux config options: propagated to domain0  ****/
/*   "acpi=off":      Disables both ACPI table parsing and interpreter.   */
/*   "acpi=force":    Overrides the disable blacklist.                    */
/*   "acpi=strict":   Disables out-of-spec workarounds.                   */
/*   "acpi=ht":       Limits ACPI from boot-time to enable HT.            */
/*   "acpi=noirq":    Disables ACPI interrupt routing.                    */
This disables ACPI for interrupt delivery.

  Published under the terms of the GNU General Public License Design by Interspire