If you want to get VirtualBox running on Fedora 12, it’s really not that hard. Please refer to the VirtualBox website for more up to date instructions.

FIrst thing you need to do is install dkms, and kernel-devel.

localhost$ su -
root@localhost$ yum install dkms

If you don’t do the above step, and are running a vanilla Fedora 12 the later step of installing VirtualBox will not be able to finish and complain about

“No precompiled module for this kernel found — trying to build one. Messages emitted during module compilation will be logged to /var/log/vbox-install.log. Compilation of the kernel module FAILED! VirtualBox will not start until this
problem is fixed. Please consult /var/log/vbox-install.log to find out why the
kernel module does not compile. Most probably the kernel sources are not found.
Install them and execute”

Now we can move on to adding the VirtualBox repo:

wget -q http://download.virtualbox.org/virtualbox/debian/sun_vbox.asc -O- | rpm --import -

Now you are good to go…

root@localhost$ yum install VirtualBox

# There is a compile step in this installer, and make take a few minutes.#

If you happened to have tried installing VirtualBox and ran into the above “Compilation of the kernel module FAILED!” message, just install dkms then ‘/etc/init.d/vboxdrv setup’ (Compiling will take some time probably).

KVM issues
Apparently the KVM kernel modules(which you would have if you were using the Fedora Virtual Manager) aren’t compatible with VirtualBox. There is a bug filed but as a workaround (or possibly just the easiest solution) is:

root@localhost$ modprobe -r kvm_intel