Resolution issues after kernel update

[n0madsoul]

Hello everyone,

I am running into some very serious problems and desperately need help.

My system with Linux Mint 18.3 and Windows 10 dual boot setup on a machine with Nvidia GeForce 1050 Ti graphics card was running fine until very recently there was a kernel update which corrupted things.

At first the system wasn't booting up in the right resolution, but sometimes did again when I switched between Windows and Mint. By trying to resolve the issue I seriously broke everything to the point that NO higher resolution than 640x480 at all was possible. Even the BIOS splash screen appeared in low resolution, making it inaccessible.

Even a fresh install of Linux Mint 19 did NOT change this: still low resolution straight from the very first seconds after booting.

I then suspected that it might be a problem with the monitor. I actually bought a new one, connected it, and everything was working fine straight out of the box, 1920x1080 resolution with a fresh Mint 19 install. Then, after updating drivers and kernel, again the same problem. I now only have 800x600 resolution available, and ONLY with nouveau driver enabled, everything else gives me black screens or reboot/crash loops. Still it seems like whatever software I put on now doesn't affect this, it is somehow written deeper into the system (or even the monitor itself?) that it is not detected anymore.

What I tried:

- everything from this thread: https://askubuntu.com/questions/968365/ ... creen-loop
- various nvidia-drivers, 384, 390 and 396 with various Kernel modelines (nomodeset, nvidia-drm.modeset etc.)
- and obviously all of the above-mentioned: fresh install, changing monitors, checking cables

At some point I read that there is some sort of ROM in every monitor which provides information about what resolutions are acceptable (EDID?). Googling about EDID only gave me very troublesome tutorials with extensive warnings attached. I did not go down that road by now.

Still, any help is very much appreciated, because it seems like I just ruined 2 monitors with this. Additional info: Monitor is connected via DVI.

I can still login on the system with 800x600 resolution in CPU rendering fallback mode, so I'll gladly provide you with whatever logs etc. you need.

Thank you for any help!

[Hoser Rob]

Unfortunately having a new kernel breaking things isn't as unusual in Linux as most beginners think. Which is why it's always recommended that, when cleaning out old kernels, always keep the last one that worked. Assuming you still have the last kernel, I'd suggest booting from that.

[n0madsoul]

Thank you for your reply. I recently made some progress installing a bleeding edge 4.18-kernel with ukuu. After that, at least the POST Screen showed up in the right resolution and Mint had not only 800x600 but 1024x768 available. That quickly changed back to the old problem after rebooting once.

Since I tried a fresh install, I have no older kernels available. I will now use ukuu and try some older ones, but since the problem persists even with a fresh install of Mint before any updates, I assume the problem is located way deeper.

[gm10]

Since this was just yesterday:
viewtopic.php?f=90&t=275758&p=1514090#p1514090

Note that his problem turned out to be a bad/not correctly plugged in cable. Which may very well be your case. There's also a link with instructions on how to add custom resolutions though.

[n0madsoul]

Thanks for pointing this out. It's getting more and more weird. I just plugged in the old monitor with the same cable and the boot resolution was fine. Then the system crashed and then it was bricked again. Plugged in the new one again and the same procedure. Could very well be this rainbows cable. There is no possibility that the system overrides some files or whatever according to which monitor it detects, right? Sorry for asking dumb questions here, but this just feels very counter-intuitive to everything I thought I know about computers at all.

[gm10]

There is no possibility that the system overrides some files or whatever according to which monitor it detects, right? Sorry for asking dumb questions here, but this just feels very counter-intuitive to everything I thought I know about computers at all.

I don't think it's dumb questions. No, the Linux system doesn't change anything permanently. But both your BIOS and later the Linux system query the monitor itself for its capabilities, and along with the capabilities of the graphics card then pick the best mode. The automatic detection can go wrong, but it's rare, this technology is tried and hasn't really changed in 20 years, just the interfaces have. In my experience the culprit is typically the hardware, and the cable/the way you connect it is on top of the list there, can also be the ports though. If you've got another cable to test with (from another monitor) test that out first.

Otherwise there's nothing much you can do for the bad resolution at the BIOS (except maybe a BIOS update), but you can also force both GRUB and the Linux kernel to use a specific resolution at boot time already. When working with changing outputs that's generally not the best approach, though. And once the Linux graphical environment has loaded, you can adjust the X server output resolution as explained in the thread linked in the thread I linked (link-ception ).

[n0madsoul]

Alright, thank you so far. I'm gonna buy a decent HDMI-cable tomorrow and will report results. Unbelievable that this might be the issue, I've been struggling with this for 3 days straight.

[n0madsoul]

With a frehsly bought HDMI cable everything works fine. Thanks @gm10 for putting me on the right track.