Unmerging nvidia drivers => Difficult to diagnose problem

[Hobbes2100]

So, I can think of three scenarios where you might unmerge your nvidia drivers and not realize that there is a problem:

1) you copied a list of packages from one machine (presumably with a nvidia card in it) to another machine (that doesn't have an nvidia card) and did a

Code:

cat pkg.list | xargs emerge

or some such and then realized your mistake and unmerged the nvidia packages

2) you upgraded your hardware and no longer have an nvidia card so you unmerged the nvidia packages

3) you were flailing around and for a random reason emerged the nvidia packages and then unmerged them.

Now, you'll note that the post install portion of the nvidia ebuilds will automatically switch the openGL libraries that you are using to the nvidia libs. However, unmerging the nvidia drivers will not automatically revert to the standard X openGL libraries and include files.

Among other things, this cause me the following problems:

1) Trying to run X would result in libraries not being loaded and startx would fail

2) Trying to run X would succeed but various libraries (dri, glx, etc.) would fail to load.

3) PyQT emerge failed.

4) Wine emerge failed (this may or may not related).

The first two problems appeared to me to be issues with my i845G chipset software: DRM kernel module (830) / X Server driver (810). Of course, since they were not the problem, this took an awful long time to diagnose.

The solution is to run