14.04.04 crashes during boot after kernel upgrade

[Silent Observer]

Not long ago (I'm not certain how long) I got a set of system updates that included a kernel upgrade to linux-image-3.13.0-93-generic -- which my research suggests was needed to patch a keyring vulnerability that could let a malicious user make the system crash. Unfortunately, I've never been able to complete a boot with that kernel; I've had to use my legacy GRUB to start "previous kernel" which is currently running linux-image-3.13.092-generic. Not much of a security upgrade if you can't actually run it, right?

I presume I'll want/need to uninstall that kernel version once I have an updated one that runs, so my "previous kernel" safeguard will continue to work -- but does anyone know what might cause this problem? I don't have a screen image; can't store one because the failure occurs before screen shots can be stored, but I can take a picture of the final text on the screen at that point, if it'll help -- even a video of the relevant boot sequence, if I have a way to upload that kind of file.

How can I either make this version run, or know what version to replace it with?

[vinnywright]

what video/graphics card do you have ?

it could be a bad driver rebuild during the upgrade/update ,,,,

boot to your working kernel and run

sudo apt-get update && sudo apt-get  dist-upgrade

do you get any errors/warnings ?

is the "dkms" package installed ,,,,,,,,it handles auto-building of kernel modules.

as a last step you can remove the non booting Kernel

sudo apt-get remove --purge linux-image-x.x.x-xx linux-image-extra-x.x.x-xx linux-headers-x.x.xx

then rerun

sudo apt-get update && sudo apt-get  dist-upgrade

VINNY

[Silent Observer]

Okay, I ran

sudo apt-get update && sudo apt-get dist-upgrade

and received no error messages; it finished with the following:

The following packages were automatically installed and are no longer required:
  libhdb9-heimdal libkdc2-heimdal linux-headers-3.13.0-83
  linux-headers-3.13.0-83-generic linux-headers-3.13.0-85
  linux-headers-3.13.0-85-generic linux-headers-3.13.0-86
  linux-headers-3.13.0-86-generic linux-image-3.13.0-83-generic
  linux-image-3.13.0-85-generic linux-image-3.13.0-86-generic
  linux-image-extra-3.13.0-83-generic linux-image-extra-3.13.0-85-generic
  linux-image-extra-3.13.0-86-generic
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

According to Synaptic, dkms is installed; I have version 2.2.0.3-1.1ubuntu5.14.04.7, which is the latest available (again, according to Synaptic).

I removed the 3.13.0-93 kernel version successfully; I'm waiting now for it to reinstall -- and, without any error messages,

sudo apt-get update && sudo apt-get dist-upgrade

installed nothing.

I'm now running

sudo apt-get install

with the same package names that were removed earlier, and that does appear to be doing something -- I'm getting errors asking me to install linux-headers-3.13.0-93-generic and linux-headers 3.13.0-93-lowlatency. I'm not sure installing them after the image and extra files are present will allow dkms to build in the nVidia drivers.

I do note that I have both /boot/vmlinuz-3.13.0-93-generic and /boot/vmlinuz-3.13.0-93-lowlatency, but I don't think the vNidia driver got baked in . I'll try rebooting to that kernel, and if it only takes me to a text login, I'll try to figure out what I did wrong when reinstalling, remove that kernel, and try again.

[Silent Observer]

Okay, I'm not sure when the video got baked into the kernel during that install, but I've now got this:

uname -a
Linux Kubuntu64 3.13.0-93-lowlatency #140-Ubuntu SMP PREEMPT Mon Jul 18 22:41:33 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

and Driver Manager says I'm using (recommended) nVidia 352.63. So, I guess that's fixed it, other than a lingering curiosity why there are now two kernel versions (generic and lowlatency) and how the system chooses between them during boot...