I was just building a new virtual machine based off an existing image that didn’t have the Virtual Box Guest Additions enabled. The guest additions allow tight integration between the guest OS and the host environment, providing seemless mouse transfer and the ability to take advantage of full video screen size. The guest additions need to be linked with the kernel which requires the kernel-devel package to be installed. After installing this package and then trying to add the guest additions it failed, suggesting that I might not have the kernel-devel package that I had installed. After a little though I finally realized what had happened. When I grabbed the kernel-devel package I hadn’t checked the version of my kernel. The kernel-devel I downloaded didn’t match the revision of the kernel I was running! Hence my problems. I upgraded the kernel to the same revision as my kernel-devel package and rebooted. I had installed dkms so I was pleased to see that my VBox Additions successfully built and the mouse and screen now worked as expected.
So now you know my embarrassing story for the day :-)