Red Hat ENTERPRISE LINUX 5 - VIRTUALIZATION GUIDE Manual page 336

Chapter 31. Tips and tricks
Verify which kernel is in use
2.
The kernel-xen package may be installed. Use the uname command to determine which kernel is
running:
$ uname --r
2.6.18-159.el5xen
The present kernel, "2.6.18-159.el5xen", is running on the system. If the default kernel,
"2.6.18-159.el5", is running you can skip the substep.
Changing the Xen kernel to the default kernel
•
The grub.conf file determines which kernel is booted. To change the default kernel edit the
/boot/grub/grub.conf file as shown below.
default=1
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-159.el5)
root (hd0,0)
kernel -/vmlinuz-2.6.18-159.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd -/initrd-2.6.18-159.el5.img
title Red Hat Enterprise Linux Server (2.6.18-159.el5xen)
root (hd0,0)
kernel -/xen.gz-2.6.18-159.el5
module -/vmlinuz-2.6.18-159.el5xen ro root=/dev/VolGroup00/LogVol00 rhgb quiet
module -/initrd-2.6.18-159.el5xen.img
Notice the default=1 parameter. This is instructing the GRUB boot loader to boot the second
entry, the Xen kernel. Change the default to 0 (or the number for the default kernel):
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-159.el5)
root (hd0,0)
kernel -/vmlinuz-2.6.18-159.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd -/initrd-2.6.18-159.el5.img
title Red Hat Enterprise Linux Server (2.6.18-159.el5xen)
root (hd0,0)
kernel -/xen.gz-2.6.18-159.el5
module -/vmlinuz-2.6.18-159.el5xen ro root=/dev/VolGroup00/LogVol00 rhgb quiet
module -/initrd-2.6.18-159.el5xen.img
Reboot to load the new kernel
3.
Reboot the system. The computer will restart with the default kernel. The KVM module should be
automatically loaded with the kernel. Verify KVM is running:
$ lsmod -| grep kvm
kvm_intel
kvm
322
85992 1
222368 2 ksm,kvm_intel