Unable to start lightdm after switching graphics provider
Hello again everyone.
Recently my video card got busted so I had to switch to using onboard graphics from my cpu/motherboard. Back when the video card worked, it was connected using an HDMI cable. I'm now using DVI cable to connect to the motherboard, but it's still the same monitor. During boot, Manjaro says it is now unable to start lightdm. It goes to a loop of starting lightdm and unable to start lightdm, and then at some point later it tries to download a mirror list or something. It's probably trying to download a solution to the problem, but I press the power off switch at that point because a.) I'm not very comfortable with allowing network usage during the boot process, and b.) my gut feeling is that this is a problem that can be fixed from a live usb and it might be a good opportunity to get down and dirty on a Linux system so to speak. Any ideas on how I can fix the issue? I don't think it's a driver problem because iirc the package manager even updates radeon drivers even if I don't have a single piece of AMD hardware on this computer, but I'm not 100% certain on that. Even if it is a driver issue, it still sounds like something I can fix by booting a live usb and doing a little fiddling, I just have no idea what exactly am I supposed to do. Thanks for your time. |
Are you sure the video card "got busted" and not Manjaro? What model was that card? It may be that you had special video configuration for that card and need to remove it. Likely you don't need a live USB boot. Likely you can hit the e key when a boot menu appears, and edit the linux line by appending " 3", then proceeding to boot in text mode, where you can login and collect data for troubleshooting. You should post here the content of /var/log/Xorg.0.log if it exists, otherwise in ~/.local/share/xorg/Xorg.0.log, plus /etc/X11/xorg.conf it if exists, and the output from
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inxi -Gxx |
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-crashing to a single color randomly while the computer is in use (usually white for Manjaro, purplish for Windows 7). Curiously, it usually crashes while idle on desktop or when I'm on the browser, rather than 3d games which I think are much higher loads. -on Windows it would sometimes reboot by itself after the previously mentioned screen -if audio was playing at the moment of crash, it would keep repeating the last second or half-second of audio until reboot -one time after automatically rebooting, there were squiggly purplish/rainbow lines at the POST screen -my first hunch was loose or bad cable, so I switched from HDMI to DVI, but at that point, I was never able to get any video when connected from the card again after powering on. Both HDMI and DVI connections were okay when connected to the motherboard, though. I'm only sticking to DVI because I don't like how the HDMI cable "snaps" in like it might break. My own personal non-expert opinion thinks that's a busted graphics card, although it's an Nvidia 750ti with dual fans that are still working so I'm also not convinced that it failed by toasting itself. I'll try your solution when I get back to the problem machine. Thanks in advance for the response. |
so did you take the card out?
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and your fears ("not comfortable") are completely unfounded. you need to boot to a command line and start investigating the problem. i believe mrmazda already provided some commands to start troubleshooting with. |
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You need to reconfigure X to work with the new graphic card! Provided the new graphic card works and is used by Linux.
That is step 1.. After that you might check if the old graphic card might still work.. But as of now, reconfigure X to work with your CURRENT graphic card. I'm not aware of special things applying to Manjaro nor Arch, but perhaps you can try something like this (from Arch manual): Code:
# Xorg :0 -configure Or try "mhwd --help" as this seems like a multitool in Manjaro and could contain alot of important tools, including the one you need. If nothing else helps, you can always configure your xorg.conf file manually. |
Xorg -configure at least 99.99% of the time is a complete waste of time, assuming it doesn't segfault, which is common. What it does is create a skeleton xorg.conf that matches the default configuration provided by the automagic configuration template. The xorg.conf it creates is loaded with non-video configuration that serves only to conflate the file and confuse someone trying to escape from gfx trouble. The limited video config it includes is no different from what automagic tries to use.
The place to start when using a new video card is to strip all manual configuration from /etc/X11/ and elsewhere so as to give Xorg's automagic configuration system that works 99+% of the time with FOSS drivers a chance to do its magic. The required stripping isn't necessarily easy if the old configuration was created by installing proprietary drivers, such s NVidia's. For that, following the NVidia installation driver section on uninstallation is the least that is usually necessary. NVidia driver installation typically includes changes in Grub configuration that need to be reverted, removal of nomodeset from the kernel cmdline in particular, since all the most popular FOSS drivers require KMS to be enabled in order to function. |
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Okay, I tried the easiest solution first which was to uninstall Nvidia drivers. The boot messages are no longer looping lightdm errors, so I guess this is progress. However, it's still not booting to anything graphical. After a bunch of green success messages, it just sits there at the blinking "_" cursor (if it just cleared a full screen of messages, it would be a blank screen with nothing but the cursor, but sometimes some previous messages are left on the screen). In any case, I don't think it crashed because pressing the power button will flood the screen with routine shutdown messages.
Near the start of the boot process, it says failed to start Load Kernel Modules, which I think was also there before I uninstalled the drivers (it's hard to notice because it gets flooded too fast by the next messages). There was no nomodeset argument on the linux line, the arguments there after the long target strings are rw \ quiet. I remove quiet since I think it only prevents some messages from displaying, but I didn't touch the rest of the arguments although I think \ stands for the command continuing to the next line. |
This is where you probably need to blacklist a kernel module. Alternatively you can use the tools in your distro to build a new kernel, or you can build one manually.
To blacklist a kernel module create a file named nameofmodule.conf under /etc/modprobe.d and add a single line in the file, like "blacklist nameofmodule". For further info of the problematic issue, inspect your dmesg file or journalctl -b. |
Blacklisting is for use of proprietary NVidia drivers. The apparent current (posts 9 & 10) objective is eradicating all traces of NVidia drivers, to give one of the FOSS drivers (nouveau or modesetting) a chance to work. They can't if either remains blacklisted after a failed attempt to undo NVidia driver installation.
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can you now switch to another tty? by pressing e.g. Ctrl+Alt+F2? then login with your usual credentials? from there you should start collecting some information & show it to us. on a wild guess, i'd say lightdm or even X is still trying to start but fails, so you might want to disable that and see if you can get a normal command line boot. |
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I think I got it back working now, assuming it's not about to hit me with another error somewhere, although it looks fine so far.
When I said I uninstalled the Nvidia driver, I meant I ran the pacman command. I checked the Manjaro wiki going from the advice: Quote:
Before I mark the thread solved, I wanna ask if there's any universal/common denominator way to do this across distros. I got lucky since Manjaro has mhwd, but can I expect other beginner friendly distros to have something similar? It feels to me like the more mature distros won't have such a tool because their answer to that is on the user's knowhow. Also, is there any way to set the system up to use whichever graphics provider is available when the previous hardware is no longer present? This may sound spoiled, but I'm only asking because this wasn't an issue with Windows and I'm not familiar enough with Linux to distinguish between "it can't do that because it's different" and "it can do that, but you have to x, y, z...". Thanks for all the responses, everyone. It would have taken me forever to get things done by myself. |
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