See Installed Kernels
In Debian & Ubuntu, we can see the installed kernels with:
% dpkg --list | grep linux-image
ii linux-image-3.16.0-4-amd64 3.16.51-3 amd64 Linux 3.16 for 64-bit PCs
ii linux-image-3.16.0-6-amd64 3.16.56-1+deb8u1 amd64 Linux 3.16 for 64-bit PCs
ii linux-image-4.9.0-11-amd64 4.9.189-3 amd64 Linux 4.9 for 64-bit PCs
In Fedora / CentOS / RedHat / RHEL:
%rpm -qa kernel
Switching Kernels With GRUB
The easiest / cleanest way to switch kernels is to select from among the installed kernels at boot time using the GRand Unified Bootloader, GRUB. By default, though, you may find GRUB doesn’t remember your last kernel selection & then you find yourself re-selecting every time. Annoying. Fix this:
% cd /etc/default
% vim grub
We want to make sure these 2 lines exist in this file:
If you have a line like this:
You should remove that line so as to have only one GRUB_DEFAULT entry.
So now, when you make your kernel selection at boot time, that selection should work automatically on subsequent boots.
Check out this section of the grub docs for more details.