installing a second linux kernel

This week, a friend of mine complained that her linux install was freezing at random times and the only way to fix it was to restart the computer. I have had this issue previously and I wasn’t able to fix it even after reading through several pages of journalctl (probably because I am dumb T-T). Eventually, this issue was fixed when I installed a new kernel so it was probably a bug with the linux kernel, or drivers interfering with the kernel. In such situations downgrading to a previous kernel can be messy so I usually keep a second kernel installed (usually the lts kernel) as a fallback.

Here is a short guide on setting up a second kernel in your archlinux install (lts in this case):

1. Install the second kernel of your choice

   You can choose from:

   • linux - latest stable
   • linux-lts - long term support kernel, best option for stability and old hardware support
   • linux-hardened - if you are very concerned with security of your system, also note that some program will not work on this kernel
   • linux-zen - tweaked for performance

   I will be installing the linux-lts kernel:

    sudo pacman -S linux-lts
   

2. Customize grub menu

   After installing the kernel, our next task is to update the grub menu so that we can choose to run a different kernel on startup but before doing that we can customize the way the menu is organized (I do not prefer the default options).

   • Edit /etc/default/grub. Note that you need sudo privilege to do so.

     First disable the submenu, for most setups it is better to be able to see the kernel options all at once. Modify this line to:

       GRUB_DISABLE_SUBMENU=y
     

     Next, in the situation that you started to use the linux-lts kernel in order to avoid bugs (as mentioned before) introduced in the linux-zen (assume), you would prefer to continue to run the lts kernel until a new kernel update arrives for the linux-zen kernel. Hence, it is preferred that the grub menu remembers your previous choice.

     Add these new lines for this feature:

       GRUB_DEFAULT=saved
       GRUB_SAVEDEFAULT=true
     

   • Save this file and exit the editor.

3. generate a new grub config file

   We now have to generate a new grub config file to add an entry for the new kernel and also to take into account our new grub options.

    sudo grub-mkconfig -o /boot/grub/grub.cfg
   

On rebooting the system, we should now see a new entry on the grub menu.