if you have installed new setup of centos minimal or you haven’t installed yet, you need make, gcc, kernel-devel in order to Install VirtualBox Guest Additions installation script.
yum install gcc make kernel-devel
Install VirtualBox Guest Additions
Mount your guest addition
you need to be as root or ‘su’ and then type:
cd /opt mkdir cdrom mount /dev/cdrom /opt/cdrom cd cdrom ./VBoxLinuxAdditions.run
if you have errors, check the reason. on centos minimal, Xorg related errors are acceptable 😉
Reboot, and you’ have VirtualBox Guest Additions on Centos Minimal!