I installed kali-2.1.2-rpi2.img on an SD card to try out on my Raspberry Pi. It works OK, but I need to compile a driver for my wifi card. For that I need kernel headers. And the kernel headers for the kernel that came pre-installed, 4.1.19-v7, don't seem to be available.

So I did what I usually do, install a new linux-image. I installed linux-image-4.9.0-kali3-armmp. (Version number is shown as 4.9.13-1kali3). I can see that that's what's in /boot. But when I reboot, it just comes back as 4.1.19-v7. Is there something else I need to do to upgrade the kernel?

Perhaps I need to install a new kernel.img on the boot partition, but I can't find clear instructions on doing that. Other distributions I've used on the Raspberry Pi haven't needed anything except apt-get.