If the OS has a problem with the existing kernel you may boot the OS with another existing kernel.

To check which kernel is enabled now

[root@mt-oracle6 ~]# uname -r

4.1.12-61.1.28.el6uek.x86_64

To change the kernel we need to edit;

#vi /etc/grub.conf

You will then see this configuration file

 

# grub.conf generated by anaconda

#

# Note that you do not have to rerun grub after making changes to this file

# NOTICE:  You have a /boot partition.  This means that

#          all kernel and initrd paths are relative to /boot/, eg.

#          root (hd0,0)

#          kernel /vmlinuz-version ro root=/dev/mapper/VolGroup-lv_root

#          initrd /initrd-[generic-]version.img

#boot=/dev/sda

default=0

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title Oracle Linux Server Unbreakable Enterprise Kernel (4.1.12-124.36.4.el6uek.x86_64)  –>0

root (hd0,0)

kernel /vmlinuz-4.1.12-124.36.4.el6uek.x86_64 ro root=/dev/mapper/VolGroup-lv_root rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=uk LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=VolGroup/lv_swap SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=VolGroup/lv_root rd_NO_DM rhgb quiet

initrd /initramfs-4.1.12-124.36.4.el6uek.x86_64.img

title Oracle Linux Server Red Hat Compatible Kernel (2.6.32-754.27.1.el6.x86_64)  —>1

root (hd0,0)

kernel /vmlinuz-2.6.32-754.27.1.el6.x86_64 ro root=/dev/mapper/VolGroup-lv_root rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=uk LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=VolGroup/lv_swap SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=VolGroup/lv_root rd_NO_DM rhgb quiet

initrd /initramfs-2.6.32-754.27.1.el6.x86_64.img

title Oracle Linux Server Unbreakable Enterprise Kernel (4.1.12-61.1.28.el6uek.x86_64)   —>2

root (hd0,0)

kernel /vmlinuz-4.1.12-61.1.28.el6uek.x86_64 ro root=/dev/mapper/VolGroup-lv_root rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=uk LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=VolGroup/lv_swap SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=VolGroup/lv_root rd_NO_DM rhgb quiet

initrd /initramfs-4.1.12-61.1.28.el6uek.x86_64.img

title Oracle Linux Server Red Hat Compatible Kernel (2.6.32-696.el6.x86_64)  —>3

root (hd0,0)

kernel /vmlinuz-2.6.32-696.el6.x86_64 ro root=/dev/mapper/VolGroup-lv_root rd_NO_LUKS  KEYBOARDTYPE=pc KEYTABLE=uk LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=VolGroup/lv_swap SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=VolGroup/lv_root rd_NO_DM rhgb quiet

initrd /initramfs-2.6.32-696.el6.x86_64.img

 

The green highlighted lines are the kernels which installed before

 

We have 4 kernels in total with this VM, If you could change default value as 2 and reboot the OS that kernel will be enabled.

To change it press “i” go to line and change value as 2

To save the file

“:wq”

You need to reboot the VM to complete the task