Your system can have multiple kernels (or versions) of Linux. The default kernel is usually set to the newest one, but can be adjusted to user preference.

First, you need to identify and adjust the kernel ids used in the boot loader config file.

Find the kernel id

Find kernel id with bootctl

  1. Change to the root user with sudo -s and enter your password.

  2. Check which kernel is currently set as default with:

       $ bootctl list

  3. The terminal will display installed kernel information, indicating which kernel was (selected) at boot, and which one is set as (default).

      # kernel currently booted and set as default 
   type: Boot Loader Specification Type 1 (.conf)      
  title: EndeavourOS (0.0.0-arch0-0)  (default) (selected) # current
     id: <current-default-id>-0.0.0-arch0-0>.conf
 source: ...
sort-key: endeavouros-0.0.0-arch0.0
version: 0.0.0-arch0.0
machine-id: <current-default-id> # current default id
  linux: ...
  
      # kernel to set as default at boot
   type: Boot Loader Specification Type 1 (.conf) 
  title: EndeavourOS (0.0.0-arch0-0)
     id: <new-machine-id>-<version>-arch<#.#>.conf
 source: ...
sort-key: endeavouros-0.0.0-arch0-0
version: 0.0.0-arch0.0
machine-id: <new-machine-id> # id to set as default
 ```

  4. Copy the machine-id of the kernel you want to set as the default.

Use cat to view current boot config

You can use cat to view the boot loader config file with a simpler output.

  1. Enter sudo cat /efi/loader/loader.conf to display the boot loader config.

       $ sudo cat /efi/loader/loader.conf
 default <your-machine-id>*  # kernel id
 timeout 20
 console-mode auto
 reboot-for-bitlocker 1

  2. Your current default machine-id is displayed.

Edit boot loader config

Terminal window showing the loader.conf file being edited with GNU nano editor

  1. Enter nano /efi/loader/loader.conf in the terminal to edit the boot loader config.

  2. On the line containing default, replace the old machine-id with the updated id.

  3. Add a wildcard/asterisk after the id (no space in between). This ensures the same kernel is booted regardless of release version, which can change after system updates.

        default <machine-id>* # add wildcard *
  timeout 20  # wait time (sec) before system boots default
  console-mode auto
  reboot-for-bitlocker 1

  4. Double check the kernel id you entered is an exact match with the one from bootctl list.

  5. Press Ctrl+X to finish editing, then press Y to save the updated config.

Verify and reboot

  1. Run bootctl list again to verify the desired kernel has (default) by the kernel title.

          type: Boot Loader Specification Type 1 (.conf) 
   title: EndeavourOS (0.0.0-arch0-0)  (default) # new default
      id: <new-default-id>-0.0.0-arch0-0.conf
  source: ...

  2. Reboot the system to check that the correct kernel boots by default.

Useful resources

Last updated 22 Nov 2022, 12:36 +0000. history