Server stalled on Loading Kernel Modules without chroot - What to do?

Today we had a server stalled on "Loading kernel modules" at reboot (after adding 12GB of RAM, to 24GB total). The datacenter didn't know what to do and they put us on a 32-bit rescue mode console from which we couldn't (obviously) launch a 64bit chroot to update the kernel. The situation seemed pretty desperate. Our sysadmin, Jérôme, once again came to the rescue. Waiting for the datacenter to respond would have potentially increased reboot time up to 45 minutes. The only possible thing to do: replace initrd with a similar version (just in case the first one would have been damaged).

VirtualBox and Ubuntu packages

VirtualBox is a very practical application running under Linux systems, and packaged into Ubuntu 8.04 Hardy Heron, that lets you virtualise an operating system. A bit in the same way as QEmu did it, except that, to make it short, it works better. Anyway, VirtualBox is highly dependent on the kernel of the base system you're running it on, so it is linked to the kernel packages in Ubuntu. The only problem is that, when upgrading your kernel with the usual Ubuntu package updates, you don't get an update for the VirtualBox right away.

HOWTO Build a Linux kernel module out-of-tree

This article is incomplete and was first written in June 2006
for the BeezNest technical website (http://glasnost.beeznest.org/articles/340).
It could happen that you badly need to use a newer kernel module than what is present on your existing Linux kernel (2.6.x), but you do not want to upgrade the whole kernel or rebuild it from scratch, because:
  • you cannot or don't want to reboot afterwards
  • you don't have the original source anymore (and your kernel was patched) or you don't want to download and install them, but you do have the kernel headers handy
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