Change default kernel - denis-kol4ev/OraDBA GitHub Wiki

Change default kernel (RedHat based OS)

changing-the-default-kernel-in-oracle-linux-its-as-simple-as-1-2-3

Supported by Oracle Linux 7.0 and later. Tested on OEL 8.9

1. Check default boot kernel

# uname -r
5.4.17-2136.324.5.2.el8uek.x86_64

# grubby --default-kernel
/boot/vmlinuz-5.4.17-2136.324.5.2.el8uek.x86_64

2. List all the kernels that are installed

# grubby --info=ALL | grep ^kernel
kernel="/boot/vmlinuz-5.4.17-2136.327.2.el8uek.x86_64"
kernel="/boot/vmlinuz-5.4.17-2136.324.5.2.el8uek.x86_64"
kernel="/boot/vmlinuz-5.4.17-2136.307.3.1.el8uek.x86_64"
kernel="/boot/vmlinuz-4.18.0-513.11.0.1.el8_9.x86_64"
kernel="/boot/vmlinuz-4.18.0-477.27.1.el8_8.x86_64"
kernel="/boot/vmlinuz-4.18.0-372.9.1.el8.x86_64"
kernel="/boot/vmlinuz-0-rescue-ea5162ec76554c44b47d21a81379e188"

3. Change to a different default kernel

# grubby --set-default /boot/vmlinuz-5.4.17-2136.327.2.el8uek.x86_64

The default is /boot/loader/entries/ea5162ec76554c44b47d21a81379e188-5.4.17-2136.327.2.el8uek.x86_64.conf with index 0 and kernel /boot/vmlinuz-5.4.17-2136.327.2.el8uek.x86_64

4. Reboot host

# shutdown -r now

6. Check new default boot kernel

# uname -r
5.4.17-2136.327.2.el8uek.x86_64

# grubby --default-kernel
/boot/vmlinuz-5.4.17-2136.327.2.el8uek.x86_64