10de:0a6c [Dell Latitude E6410] nouveau fails when logging in to Ubuntu/Kubuntu with kernel 3.7.0-2

Do you mean the PGRAPH errors in dmesg? Any other errors displayed to the console or other logs?

Your report is a bit ambiguous on one point: You say you've been seeing the bug "since Quantal, around Beta2", however you later say that "Booting back on the current Quantal kernel" restores it to working. Care to clarify? By chance could you be lumping two distinct bugs together?

Focusing on the raring 100% failure on login. There are mainline kernels at http://kernel.ubuntu.com/~kernel-ppa/mainline/ you can try testing. If it were me, I'd start at 3.5-quantal and verify that works, then test v3.7-rc6-raring and verify that fails, then randomly test kernels between those versions to narrow down when the regression first starts.

This change was made by a bot.

@Bryce: I started having problems around Quantal Beta2, Unity, and found that moving to the nVidia proprietary driver would either eliminate the problem, or make it very rare (I did not experience this issue at all with the proprietary driver). But the proprietary driver sucks in terms of setting multiple monitors -- I could not set them up unless by trying again and again (which sounds very much like the definition of insanity). So I went back to Nouveau, and found that KDE would survive longer. So I moved to KDE.

Then -- last week -- I upgraded to Raring. There I simply cannot use the 3.7.0 kernel; the 3.5.0-19 suffers the same issues on Unity, but mostly works on KDE.

So, a summary (*NOTE* this seems to happen with some, but not all, nVidia cards. In my case it is a GT218 [NVS 3100M] rev a2):

* nouveau on Quantal (Unity) fails at least once a day with the errors above; failure requires machine to be power-cycled; no local access is possible
* nouveau on Quantal (KDE) is usable; similar failures are mostly observed when logging in, and require a power-cycle
* nouveau on Raring (Unity or KDE) fails during login, *always*. Raring works if booted with kernel 3.5.0-19

I will check the upstream kernels.

(all comments apply when logging in from a fresh reboot; on all cases both monitors show the login screen (lightdm-kde-greeter)
Ubuntu kernel 3.7.0-3:
 * Unity -- both monitors get the screen (almost) correctly painted; pointer moves, but nothing else can be done. The launcher is painted, with a gray/silver background, does not hide and does not respond to clicks. It does take a few minutes to reach that point
 * KDE -- only the laptop monitor got active; KDE initialisation stopped at the last step; system locally unresponsive.
Ubuntu kernel 3.7.0-2: It does take a few minutes to reach that point
 * Unity -- both monitors are active; mouse is initially quite sluggish, then not working; otherwise system is locally unresponsive; after a while, X crashes, and the greeter is redisplayed
 * KDE --only the laptop monitor is active; KDE initialisation stopped at the first step; system is not locally responsive; It does take a few minutes to reach that point
Ubuntu kernel 3.5.0-19:
 * Unity & KDE -- failures as in the previous comment.

Now for the mainlines.

failed with 3.5.0 upstream as well

It was failing so much that it got impossible to work. I moved back to nVidia proprietary (r 310), and system seems stable under Unity.

I will test, later on, KDE.

nvidia-experimental-310 works on 3.7.0-x. Did not try to go back to Nouveau.

Thanks for the additional information; it's not evident what's gone wrong but this is worth further investigation. Stick with the proprietary driver in the meantime until we have something new to test.

Btw, 'nomodeset' is not a recommended or supported option on nouveau any longer.

This change was made by a bot.

C de-Avillez, as per http://www.dell.com/support/troubleshooting/us/en/19/Product/latitude-e6410 an update is available for your BIOS (A15). If you update to this, does it change anything?

If not, could you please both specify what happened, and provide the output of the following terminal command:
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

Thank you for your understanding.