#virtualbox host oracle #linux guest howto
https://www.virtualbox.org/manual/ch02.html#externalkernelmodules
https://www.virtualbox.org/manual/ch04.html#idp96235792
after building a virtualbox oracle linux 6 vm from the dvd iso you will need to login as root and
# ifup eth0
# yum update
# reboot
# ifup eth0
# yum install gcc
# yum install kernel-devel
# yum install kernel-headers
before installing guest additions by running ./VBoxLinuxAdditions.run