Now I downgraded xserver-xorg on my machine to get a usable X11 back.
As expected, this caused some pain, because of necessary package sources, dependencies, version numbers etc. - You should only attempt it if you have some experience with apt/aptitude etc., and some time at hand to fix errors if they occur.
This may be close to what I finally did (and may be wrong, because I'm *NOT* an expert on apt!)
in /etc/apt/sources.list add these lines:
#fuer xserver mit ABI 10, letztes derzeit von nvidia 96.43.20 unterstuetztes
wheezy-backports main contrib non-free
Do (probably rather) not use anything like
# apt-get remove xserver...
because when I attempted that (just to have a look) it would have set out to remove kde (or maybe gnome, respectively), and other packages which it thought might depend on an X server (why? they could use a remote server anyway), which is probably not what you want.
You may try this instead:
# apt-get install --ignore-missing xorg=1:7.6+8~bpo60+1 xserver-xorg=1:7.6+8~bpo60+1 xserver-xorg-core=2:1.10.4-1~bpo60+1 xserver-xorg-input-mouse=*~bpo60+1 xserver-xorg-input-all=*~bpo60+1 xserver-xorg-input-synaptics=*~bpo60+1 xserver-xorg-input-evdev=*~bpo60+1 libgl1-mesa-dri=*~bpo60+1
This selects the available backports of the xserver-xorg version 1.10, that uses X.Org ABI 10 and is still compatible with the nVidia 96.43.20 driver. It also installs suitable versions of the minimum driver package set on which the xserver-xorg would depend. As long as you do not specify these packages, the system would rather default to install their newer versions, and these would not be compatible with the downgraded xserver-xorg-core etc... :-(
It is true mercy that you can provide the version numbers for most (maybe all, indeed) packages like *bpo60+1 - this will select a suitable backported version (maybe needs a different number when they are updated), and the portion represented by * will be replaced by something that's really available. Otherwise, you would have to look up individual version numbers for all(?) of these packages!
You can look up versions available for a given package e.g. like this:
$ apt-cache showpkg xserver-xorg-core
Before I had added the vesa package, even after the above command, on my system apt wanted to install a bunch of debian nvidia packages. One of these complained that it could not create a file in /usr/lib/nvidia/diversions/ and finally broke the installation process.
Even thereafter that directory didn't exist, so I made it manually (as root), and thereafter this specific package would install ok. Still, further down some other debian nvidia packages would throw errors. So finally, I removed the debian nvidia packages alltogether:
# apt-get remove nvidia*
Then, I tried to install the above package set, plus some simple vesa video driver:
apt-get install --ignore-missing xorg=1:7.6+8~bpo60+1 xserver-xorg=1:7.6+8~bpo60+1 xserver-xorg-core=2:1.10.4-1~bpo60+1 xserver-xorg-input-mouse=*~bpo60+1 xserver-xorg-input-all=*~bpo60+1 xserver-xorg-input-synaptics=*~bpo60+1 xserver-xorg-input-evdev=*~bpo60+1 libgl1-mesa-dri=*~bpo60+1 xserver-xorg-video-vesa=*~bpo60+1
This, finally, gave me an installation process that (a) completed without errors, and/because_it (b) would not try to install any debian nvidia packages.
Thereafter, I ran the nVidia installer package as downloaded from nVidia's site:
Finally, I started X11 in a short experimental fashion:
This actually did work. (You might use Ctrl-Alt-backspace to quit this server fast [if not configured out], and later on, use kdm or gdm or xdm or any other way to get it back with the normal login screen.)
Now, look which versions of which packages are installed:
# dpkg-query -l xserver*
Finally, I don't want to have these "precious" downgraded xserver-xorg package replaced by future updates (as long as nVidia don't have an updated driver, at least). I hope that I can achieve that like this:
# apt-mark hold xserver*
And then, to correct the setting for two packages I did not want to include:
# apt-mark auto obexserver isdnvboxserver
And to check what was finally achieved:
# apt-mark showhold
Ok. Everything is provided without any warranties - mainly to document the required packages and version numbers - because I didn't find anything suitable when I searched the web. This implies *no* suggestion towards anyone to attempt the same thing. Don't try it if you are not sufficiently knowledgeable and experienced. Your mileage may vary. :-)
Kind regards, Joerg