Freebsd 9.3-RELEASE and Virtualbox

[Rob Rati]

I've tried upgrading my 9.2-RELEASE system to 9.3-RELEASE a few times, but each time I had to revert because starting any Virtualbox VMs causes a kernel panic.  I found this thread about the issue:

https://lists.freebsd.org/pipermail/freebsd-emulation/2014-August/011767.html

What I don't understand is why it is expected that the repository kernel module wouldn't be in sync with the 9.3-RELEASE kernel. Is it because the packages are relevant to all 9.x releases and there's no way to have a kernel module work with them all?  If so, why bother having a kmod package at all?

On a related note, how difficult is it to build the kernel module?  I have never built it from source in the past and don't even have kernel sources installed.  I use stock kernels from the releases.  Are there ways this build can get screwed up if options/packages aren't correct?

Rob