Some OSes, such as Oracle Linux 6.4, do not have the Oracle Virtual Networking host drivers embedded. OSes that do not have embedded host drivers can be upgraded to a later kernel version that contain embedded host drivers. In this case, the OS would come with a base kernel, which does not have host drivers embedded in the OS. After upgrade, the OS would have a final kernel, which does have host drivers embedded into the OS.
As an option, you can decide to not embed host drivers into the host OS. In this case, the host drivers are a separate software package that you can install after the host OS is completely installed. For information about installing the host drivers as a separate software package, see the Oracle Virtual Networking host driver product notes for the corresponding host OS.