which kernels can I safely purge?

Question

I use the main answer of this question quite often to clear some space, but now I'm in extreme need and I'd like to better understand which kernels are safe to purge, my list is the following

10:50:58-673 - ~> dpkg -l | grep -Eo "^.i +linux-(image|headers)[^ ]+" | cut -c 5- | grep --color -E "$|"`uname -r`
linux-headers-2.6.38-15
linux-headers-2.6.38-15-generic
linux-headers-2.6.38-15-generic-pae
linux-headers-2.6.38-16
linux-headers-2.6.38-16-generic
linux-headers-2.6.38-16-generic-pae # current one
linux-headers-generic
linux-headers-generic-pae
linux-headers-server
linux-image-2.6.38-15-generic-pae
linux-image-2.6.38-16-generic-pae
linux-image-generic-pae
linux-image-server

Is it enough to keep

linux-headers-2.6.38-15
linux-headers-2.6.38-15-generic
linux-headers-2.6.38-15-generic-pae
linux-headers-2.6.38-16
linux-headers-2.6.38-16-generic
linux-headers-2.6.38-16-generic-pae # current one

Or would this be enough

linux-headers-2.6.38-15-generic-pae
linux-headers-2.6.38-16-generic-pae # current one

Or which other would be the shortest (keeping the previous one too)? And why?

Answer 1

I assume you're using the generic-pae kernels; it's safe to remove the -server kernels, which you aren't using.

You must keep at least one kernel image (linux-image-2.6.38-16-generic-pae, etc.). It's recommended to keep at least 2, because if an update hoses the most recent kernel, you can still boot using the previous one.

You should also keep linux-image-generic-pae, which is a tiny meta-package that causes the latest kernel to be installed.

You should keep the corresponding headers for each kernel you keep; the headers are needed to build kernel modules for that kernel.