karmic gdm restarts X infinitely when video driver fails to load

[Anders Kaseorg]

Binary package hint: gdm

If Xorg is misconfigured in a way that prevents the video driver from loading, such as this /etc/X11/xorg.conf:

Section "Device"
 Identifier "Default Device"
 Driver "drunk"
EndSection

(or, more realistically, if you’re using a proprietary driver that failed to compile for the current kernel), then gdm will respawn X repeatedly, many times per second, forever.

When this happens, it is nearly impossible to log into the console to stop gdm, because you cannot tell which characters of your password made it into the password prompt while the screen was flickering wildly. So if you want to test this, make sure you have an open console root shell with ‘stop gdm’ ready to execute.

[Daniel Letzeisen (dtl131)]

This might be related to bug https://bugs.launchpad.net/ubuntu/+source/fglrx-installer/+bug/392039
X should just fail miserably if it can't find the specified driver, no?

[Anders Kaseorg (andersk)]

This bug is about the (mis)behavior of gdm when X has already failed, with no stipulation as to what caused X to fail in the first place. So your bug is not really related.

[Niall Creech (sevenmachines-deactivatedaccount)]

noticed this when installing a kernel update, so it doesnt just affect failing drivers
1. have nvidia dkms installed on kernel
2. install a kernel update
3. reboot
4. dkms hasnt build nvidia module on kernel but...
5 gdm restarts repeatedly since X will fail because dkms hasnt finished building the driver on the new kernel yet

[Pauli Virtanen (pauli-virtanen)]

Dkms failing to build a module is not so rare occurrence, so it would be nice if this issue was addressed somehow.

Earlier in Ubuntu, when a display driver failed to work, a failsafe mode was entered. This would still be useful.

[Steve Langasek (vorlon)]

I'm opening an upstart task on this bug; I think init is supposed to have rate limiting in place to prevent jobs from respawning endlessly, I don't know why it's not taking effect here.

[Steve Langasek (vorlon)]

03:32 < Keybuk> slangasek: gdm restarts X indefinitely
03:32 < Keybuk> it's not gdm that's restarting

Sorry, closing this task back out.

[Darxus (darxus)]

I'm getting this too. My nvidia driver failed to load, my fault, but the failure mode is terrible.

Previous releases would fall back to a low resolution driver / X server, probably using vesa, and then ask you if you wanted to reconfigure your video. And if you said no it would let you just use the low resolution X.

I think this should have a higher priority.

[Carl Karsten (carlfk)]

got this after installing nvidia-glx-185 using the "restricted driver" thingy.

[Darxus (darxus)]

Carl: You should open a bug for the nvidia driver failing to install properly. This bug is for X's poor behavior under such circumstances.

[srg84 (sssr84)]

A workaround for this bug is editing /etc/X11/default-display-manager and temporaly change the line /usr/sbin/gdm.
Flickering stops and you can login, remember to edit the file again.

[Alex (alex112283)]

@srg84
Could you please be a bit more specific about what to temporarily change in the /usr/sbin/gdm line? Also, how were you able to edit that when X keeps restarting. I ask because I couldn't even log in when I had this problem.

[Darxus (darxus)]

klemperal: Select one of the recovery kernel options at the grub boot menu, at the next menu select the root shell, then run "telinit 3". You'll get a console login.

[srg84 (sssr84)]

@klemperal if you don't have another bootable kernel my solution is useless.

[Darxus (darxus)]

You could also boot one of the install disks.

And I would guess that srg84 was suggesting removing the /usr/sbin/gdm line, I haven't even looked at this file.

[Alex (alex112283)]

I was wondering about that. Anyway, thanks for the reply(s).

On Mon, Oct 19, 2009 at 2:47 PM, srg84 <email address hidden> wrote:

> @klemperal if you don't have another bootable kernel my solution is
> useless.
>
> --
> karmic gdm restarts X infinitely when video driver fails to load
> https://bugs.launchpad.net/bugs/431166
> You received this bug notification because you are a direct subscriber
> of the bug.
>
> Status in GDM: The Gnome Display Manager: New
> Status in “gdm” package in Ubuntu: Confirmed
> Status in “upstart” package in Ubuntu: Invalid
> Status in gdm in Ubuntu Karmic: Confirmed
> Status in upstart in Ubuntu Karmic: Invalid
>
> Bug description:
> Binary package hint: gdm
>
> If Xorg is misconfigured in a way that prevents the video driver from
> loading, such as this /etc/X11/xorg.conf:
>
> Section "Device"
> Identifier "Default Device"
> Driver "drunk"
> EndSection
>
> (or, more realistically, if you’re using a proprietary driver that failed
> to compile for the current kernel), then gdm will respawn X repeatedly, many
> times per second, forever.
>
> When this happens, it is nearly impossible to log into the console to stop
> gdm, because you cannot tell which characters of your password made it into
> the password prompt while the screen was flickering wildly. So if you want
> to test this, make sure you have an open console root shell with ‘stop gdm’
> ready to execute.
>

[srg84 (sssr84)]

@klemperal

hi, could you please hide my in email ? , thanks!

[Alex (alex112283)]

Sorry srg84, it looks like one of the features of launchpad is that you can't edit your posts after so many minutes. I didn't realize that replying through email would post your address and all that other stuff--again, sorry about that.

[Hiram (hiram-)]

Why is this marked as low? It happens quite often when you have a strange setup (vmware and native for example) and it leaves your system completely unusable... This is a clear regression from Jaunty and a very very anyoing bug

[hemebond (hemebond)]

This "bug" just had me locked out of my workstation for more than 30 minutes. I couldn't get into recovery mode and I couldn't get to a terminal (F1-F6). In the end I mashed ESC, got a root prompt before X started, and managed to type

rm /etc/X11/xorg.conf

quickly enough that when X leapt in it had to create a new config. This bug is terrible.

[Daniel Letzeisen (dtl131)]

Karmic/9.10 reached EOL on 4/2011 and there have been no reports of this in Lucid/10.04 or later. Marking Incomplete in case someone knows otherwise.

[Rolf Leggewie (r0lf)]

Karmic has long since stopped to receive any updates. Marking the Karmic task for this ticket as "Won't Fix".