Kubuntu 18.04 booting into terminal after resetting GPU

[deanr]

After switching to the recommended Nvidia driver I was getting dreadful screen tearing so I tried to revert back to the free drivers. I rebooted and now can't access the GUI. Here's what I'm seeing before after entering my password:





What do I need to do now?

Thanks,

D.

[Snowhog]

And if you then type: start x

[deanr]

'command start not found'

I tried with with sudo too

[Snowhog]

My bad. Try: startx

[deanr]

Hmm. OK, so it booted but the theme has changed and my mouse and keyboard aren't working at all...

[deanr]

It's a clean install so I won't lose anything by re-installing but it seems to be a rather unfortunate 'bug' if that's what it is. Especially as Kubuntu 'recommends' using the Nvidia driver.

[oshunluvr]

I'm curious if /etc/modprobe.d/nvidia-graphics-drivers.conf remained after the uninstall. Also wondering if you did any other mods prior to uninstalling nvidia.

Mouse and keyboard are part of X so that's where the problem is. IF you're interested in tracking it down, start with log file like /var/log/Xorg.0.log and see what's happening.

Frankly, unless you installed an nvidia driver that is the incorrect one for your video card, you're not going to get better performance from the free nouveau driver. You could have left the nvidia driver installed and worked on it's settings and your desktop settings to resolve the tearing problem. Things like proprietary drivers don't always work "out-of-the-box".

[claydoh]

If you do a little bit of searching, there are a number of thing that could have been tried to fix the tearing. Unfortunately, this is a common problem with this brand, but it varies from system to system as to if it happens or not, or how bad it is. For most people, the proprietary drivers are vastly superior to the Nouveau open-source driver.

If you do try to use the Nvidia non-free drivers, the most common way to fix the tearing that seems to work for the most people is to use the KWIN_TRIPLE_BUFFER=1 option as described here:
https://www.reddit.com/r/kde/comment...m_medium=web2x


Another thing that may have minged things up trying to revert back to the free driver is that Nvidia creates an xorg.conf file, and this mighjt have setting that don't work with the Nouveau driver, perhaps, or there can be stray Nvidia libraries left over, which are mucking things up. Nvidia can be messy sometimes, for sure.

I moved to AMD because of it. the free drivers there are the best ones for 99.99% of users. This obviously is not a solution for everyone, though.

[deanr]

I didn't do any other mods apart from theming: creating a top panel, deleting the bottom, change wallpapers etc. Only visual tweaks.

There were persistent pop-up messages about 'driver performance' which, when I clicked on it, opened the drivers section. I then simply clicked on the 'recommended' Nvidia driver (390) and clicked apply.

FYI, there was no tearing with the nouveau driver - the only reason I switched it was because of the recommendation. And I figured it would be easy enough to switch it back afterwards if needed.

I'm too much of a newbie (1.5 years of Mint) to even understand what's meant by 'start with log file like /var/log/Xorg.0.log' but I appreciate your help and at least I now know what to type into the terminal to get back to GUI should I encounter a similar boot issue in the future.

Ironically I've been happily playing around with Kubuntu on this second PC because it was the only distro I found, other than Vanilla Ubuntu, that didn't suffer from screen tearing! Well, that and the fact that it looks like something from the 22nd century compared to Cinnamon .

[oshunluvr]

Sorry, I meant to review the logs starting with that one. You can install "KSystemLog" if you don't like using the command line.

BTW, there's no more xorg.conf file, so if you see an old post or get help from the 'net about xorg.conf don't bother with that. The "proper" way to pass info to X for the nvidia driver is in files under /usr/share/X11/xorg.conf.d. X does a much better job of detection than it used to so rather than building an entire xorg.conf file (always a PITA) you can add sections as needed, for example you can put monitor settings in /usr/share/X11/xorg.conf.d/10-Monitor. I haven't had to do much with xorg except a laptop I had that would always default to the wrong refresh rate for my 4K monitor resulting in a black screen.

As far a screen tearing with nvidia card and drivers, you would need to post what version of Plasma you're running (found in systeminfo) and which nvidia driver. 390 is now a "legacy" driver and the current one 415.18 fixes several major bugs. If you were to tackle this again, start with looking up your exact model of card on the nvidia website and see the latest driver that supports your card.

[deanr]

No problem. Thanks both for the tips and advice etc. I've re-installed Kubuntu 18.04 and will leave the drivers as they are .