VirtualBox Guest Additions on PAE kernel

It you are using a PAE (Physical Address Kernel) kernel in a Virtual Box guest and wish to install the VirtualBox Guest additions, you need to download the kernel-PAE-devel package as well as the kernel-headers package. PAE kernels are available for Fedora, Red Hat, CentOS and more. Otherwise you will end up failing to build the main Guest Additions kernel module and getting a misleading message in /var/log/vboxadd-install.log after attempting to run sh ./ *** Error: KERN_DIR does not point to a directory. That message is misleading as the real error is due to you not having the PAE headers