Cannot create "Hello World" module (and NVIDIA, and VirtualBox)

SOLVED!

Simple as that: /root/.bashrc had this inside:

 export GREP_OPTIONS='--color=always'

Changed it to:

 export GREP_OPTIONS='--color=never'

...and restarted the root shell (of course; do not omit this step). Everything started working again. Both NVIDIA and VirtualBox kernel modules built from the first try. I am so happy! :-)

Then again though, I am slighly disappointed by the kernel build tools. They should know better and pass --color=never everywhere they use grep; or rather, store the old value of GREP_OPTIONS, override it for the lifetime of the building process, then restore it.

I am hopeful that my epic one-week battle with this problem will prove valuable both to the community and the kernel build tools developers.

A very warm thanks to the people who were with me and tried to help.

(All credits go here: http://forums.gentoo.org/viewtopic-p-4156366.html#4156366)

Have you tried purging and reinstalling dkms?

You could use apt-get purge dkms and that will also purge all the packages that depend on it, so you'll have to reinstall them afterwards.

If you don't want the dependant packages purged too, you could use dpkg:

dpkg --purge --force-depends dkms

reinstall with the usual: apt-get install dkms

FWIW, I have two machines here (running debian sid) with kernel linux-image-3.2.0-3-amd64 and the nvidia-kernel-dkms 302.17-3 and related packages installed. The dkms module compiled without a problem. A third machine (my main desktop) is still running nvidia-kernel-dkms 295.53-1, mostly because I don't want to have to logout.

BTW, you mentioned purging and re-installing the various nvidia packages with aptitude. There are several nvidia packages that don't have nvidia in the package name. Here's the solution I came up with to hold/unhold nvidia pkgs (I usually only want to upgrade nvidia pkgs when I'm willing/able to log out of my current X session...and after a few unpleasant surprises with new nvidia versions, I like to test them on my least-important machine first):

(note: you'll need my dlocate package installed to run this)

$ cat /usr/local/sbin/hold-nvidia.sh 
#! /bin/bash

PKGS=$(dlocate -l nvidia cuda vdpau | awk '/^[hi]i/ {print $2}' | sed -e 's/:.*//')

echo dpkg-hold $PKGS
dpkg-hold $PKGS

There's a nearly identical one for un-holding packages (runs dpkg-unhold instead of dpkg-hold), and it would be trivial to make it run dpkg --purge or apt-get purge instead.