Arch pacman -Syu :::: exclude kernel

To avoid having pacman -Syu update the kernel or other packages, add them to the IgnorePkg list.

Edit:

nano /etc/pacman.conf

Set as individual entries, or comma separated list:

IgnorePkg = linux
IgnorePkg = linux-headers

references:
From DigitalOcean howto
From ArchLinux wiki