(the system in question was running nvidia/kernel 3.7 at the beginning)
I had issues starting virtualbox (playing with gentoo for an upcoming post) the other day, and so decided to reboot after running apt-get upgrade (I only do it once per week/month or so -- it's my futile attempt at stability in spite of running wheezy/testing...).
On rebooting everything looked fine and I was greeted with the login screen in GDM. Trying to log in everything looks fine at the beginning...the screen flickers as if the resolution is being changed, the desktop background looks fine, conky is running...and then I'm thrown back to the GDM login again.
I'm not a stranger to other desktops. Trying KDE, LXDE, etc via GDM gave the same error.
Looking in the terminal I noticed that I had guake segfault errors, and errors along the lines of
"segfault at 968 ip [..] error 4 in libX11.so.6.3.0"
Logging in as another user gives me a message saying that I'm thrown back in to gnome classic due to lack of acceleration. Also, the desktop didn't have menus etc., and with various d-bus related errors.
update-notifier: Fatal IO error 0 (Success) on X server :0.and
No protocol specified
Display does not support NVIDIA 3D.I then ran SMXI with the intent to test Nouveau instead of Nvidia.
As part of its process, SMXI does a dist-upgrade. It's not often I encounter errors during apt-get, so when errors popped up, I paid attention.
Turns out that Zoneminder had some issue -- zoneminder had held back the configuration of packages that I pulled in during the apt-get upgrade at the very beginning. And given that I don't do it very often, there were a lot of packages that were left unconfigured, including Xorg.
I auto-remove zoneminder and completed the upgrade. So far so good!
If that had been the end of it there would be no blog post. Still things weren't working.
Since I was already exploring the possibility of switching to Nouveau, I decided to go through with it. First I backed up my old /etc/X11/xorg.conf which has served me well in the past. Then, using SMXI I installed Nouveau (after blacklisting nvidia, and removing any nouveau blacklisting).
GDM started up fine, but I had no acceleration and GNOME 3 started in fallback mode (gnome 'classic'). I tried glxgears which told me libGL.so.1 was missing.
However, libGL.so.1 actually existed in /usr/lib/x86_64-gnu/ -- but it pointed to libGL.so.1.2 via a symlink, and libGL.so.1.2 didn't exist.
I flailed about for a little while:
sudo apt-get install --reinstall glx-alternative-mesa
Which seemed to actually do stuff -- pulled in nvidia-installer-cleanup, glx-diversions, glx-alternative-mesa. It added lots of seemingly relevant diversions, but there was still no target for the libGL.so.1 symlink.
I then got fed up with the Nouveau/GNOME 3 combination.
I decided to bet on NVIDIA again, and had the fairly reasonable idea that the issue was the updated Xorg version -- simple nvidia update might've helped
Since I had kernel 3.7 installed, and 3.8 supports NVIDIA/DKMS I figured I might as well install a 3.8 kernel I had compiled on a different computer before continuing.
After upgrading to kernel 3.8, I blacklisted nouveau in /etc/modprobe.d/blacklist.conf ('blacklist nouveau').
I manually made sure that there was no nvidia or nouveau loaded by rmmod:ing them and checking with lsmod.
I then ran smxi and installed debian-nvidia.
Black screen with cursor. No graphical environment.
lsmod showed that nouveau hadn't respected my blacklisting.
Edited my /etc/default/grub to read
then ran update-grub, followed by restoring my old xorg.conf.
And...then everything worked! lsmod shows that nouveau isn't loading anymore (blacklisting should be ok, no?) and I can now log in to gnome 3 as normal with normal acceleration.
I'm not sure what the underlying problem was -- nouveau not respecting my blacklisting hasn't been an issue before, so that was a bit of a surprise. But it was probably fine before I installed nouveau (I can't uninstall it for some retarded reason since it pulls too many packages with it), and not the source of the original issues. Probably the new xorg version didn't play fine with the installed version of nvidia, which is almost expected.
I'm still peeved with the Nouveau/GNOME 3 situation though -- binary blobs shouldn't be required to simply to use a basic desktop. I can understand if nouveau isn't a stand in for nvidia -- it's a reverse engineered open source alternative after all -- but why is gnome 3 requiring so much grunt?