X.org crashes after upgrade to 18.10

[Mickaël Bucas]

After the upgrade from 18.04 to 18.10, SDDM fails to start. This happens with kernel 4.18.0-10 and 4.15.0-36 (it was the chance to discover grub-reboot)
See SDDM crash file attached.

The machine is a virtual machine, and PCI devices use virtio-pci driver for example.

I looked into /var/log/Xorg.0.log and found many error messages, the first one being :
(EE) open /dev/dri/card0: No such file or directory
See Xorg log file and crash file attached.

Then I looked at the output of 'lspci -vvnn' and it seems that no kernel driver manages the VGA Controller.
See output of 'lspci -vvnn' attached

According to the following message, the missing kernel driver may be : bochs-drm or virtio-vga
https://www.redhat.com/archives/libvir-list/2015-August/msg00220.html

# lsb_release -rd
Description: Ubuntu 18.10
Release: 18.10

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1802950/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Daniel van Vugt (vanvugt)]

Unfortunately we are unable to read crash files as attachments.

Please use this command to submit the crash file correctly:

  ubuntu-bug _usr_lib_xorg_Xorg.0.crash

That will create a new bug so please let us know here what the new bug ID is.

[Timo Aaltonen (tjaalton)]

bochs-drm will be added as part of bug 1795857

[Mickaël Bucas (mbucas)]

I couldn't upload the crash file _usr_lib_xorg_Xorg.0.crash, because ubuntu-bug wants to open a web browser, which is obviously not possible when X11 is not available.

Through an "ssh -Y" session, I got a window with the following error message :
    Sorry, Ubuntu 18.10 has experienced an internal error.
    If you notice further problems, try restarting the computer.
And in the terminal :
    QPainter::begin: Paint device returned engine == 0, type: 2
    QPainter::end: Painter not active, aborted
I was able to run an XTerm window through the same connection.

I've launched apport-bug without arguments, and it uploaded all information it could in bug #1803123

apport-bug was nice enough to show an URL to work with uploaded data. It would be nice if ubuntu-bug could do the same when uploading a crash file !

[Daniel van Vugt (vanvugt)]

If you are unable to open a web browser then please try using 'apport-cli' instead of 'ubuntu-bug'.

[Daniel van Vugt (vanvugt)]

Please try running:

  apport-cli _usr_lib_xorg_Xorg.0.crash

and then copy and paste the link it (eventually) gives you into a web browser on a different machine.

If for any reason that doesn't work then the next option is to look at https://errors.ubuntu.com/user/ID where ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine. Do you find any links to recent problems on that page? If so then please send the links to us.

[Mickaël Bucas (mbucas)]

I didn't get the above steps to work, so I choose a different way.

I've tried to compile the missing "bochs-drm" module by following these steps :

    apt-get install linux-source-4.18.0
    cd /usr/src/linux-source-4.18.0/
    tar xjf linux-source-4.18.0.tar.bz2
    cd linux-source-4.18.0/
    apt-get install bison
    apt-get install flex
    apt-get install libelf-dev
    make oldconfig
    make menuconfig

In the menus I searched and enabled the module CONFIG_DRM_BOCHS=m
Then I launched the compilation :

    make modules
    # Get some coffee
    mkdir /lib/modules/4.18.0-12-generic/kernel/drivers/gpu/drm/bochs
    cp drivers/gpu/drm/bochs/*.ko /lib/modules/4.18.0-12-generic/kernel/drivers/gpu/drm/bochs
    depmod -a
    modprobe bochs-drm

This didn't work and I got the following message in "dmesg" :
bochs_drm: version magic '4.18.17 SMP mod_unload ' should be '4.18.0-12-generic SMP mod_unload '

But I found a way to change it by editing the main Makefile and changing :
    SUBLEVEL = 17
    EXTRAVERSION =
To the values :
    SUBLEVEL = 0
    EXTRAVERSION = -12-generic

Then I restarted a clean compilation :

    make clean
    make modules
    # Get some coffee
    cp drivers/gpu/drm/bochs/*.ko /lib/modules/4.18.0-12-generic/kernel/drivers/gpu/drm/bochs
    depmod -a
    modprobe bochs-drm
    systemctl start sddm

And then I got SDDM back on screen !

I hope bochs-drm will be included in future standard kernel, as asked for in bug 1795857, because these steps will be necessary after each update of the standard kernel.

[Mickaël Bucas (mbucas)]

As I found a way to get SDDM back, I don't see a reason to keep this bug around.