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So, I changed the resolution of grub by editing the GRUB_GFXMODE line in /etc/default/grub. I also added nomodeset to GRUB_CMDLINE_LINUX_DEFAULT.

Now the problem is, that whenever I boot into Ubuntu, the resolution of grub (800x600) remains. That's not the case when I boot into Windows with grub. I also changed GRUB_GFXPAYLOAD_LINUX, but that doesn't affect my problem in any way.

Eventually I figured out that without nomodeset this problem doesn't occur. Unfortunately I need that flag, as otherwise my PC will boot into a black screen sometimes, with the only way to exit is by killing my PC off.

Any suggestions what could be the problem? I have a AMD RADEON VEGA 10 (Integrated Chip), if that's of any interest.

Information:
OS is Ubuntu MATE 20.04
The AMD Driver is the open source amdgpu. It came out of the box with Ubuntu
The GFXMODE line looks as follows: GRUB_GFXMODE=800x600
When that line is commented out the grub menu has a resolution of 1920x1080, thus making it very slow

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3
  • Commenting out GRUB_GFXMODE won't slow down anything, it'll only change your GRUB screen resolution, and may fix your black screen problem. Also, your value of 800x600 doesn't sound like your monitor/display can handle that, as it doesn't appear to be any standard size. Leave GRUB_GFXMODE commented out, set GRUB_GFXPAYLOAD_LINUX back to default, and do sudo update-grub.
    – heynnema
    Jun 17, 2020 at 14:20
  • 1
    Grub is very slow and steady, inputs are processed very slowly at high resolutions. Commenting out can't fix my black screen problem, as I only began to modify grub in order to fix my black screen. While doing so I saw the resolution option and wanted to change it, so grub becomes fast reacting. I ran videoinfo in the grub cli and 800x600 was on of the resolutions it throw back at me, so I think that works. However I already came up with a fix and answered my own question. Thank you nonetheless!
    – Timer ErTim
    Jun 17, 2020 at 14:30
  • If possible you should boot with UEFI, which will (among other things) cause grub to use your native monitor resolution.
    – Michael Hampton
    Jun 18, 2020 at 3:00

1 Answer 1

Reset to default
7

After even more research, some trial and error, and getting it to work finally, I can say, that replacing nomodeset with

modeset=0

solved my problem

It seems as nomodeset forces the display to stay at grub resolution, even after booting. I found that out here. modeset=0 also prevents a black screen, but it doesn't come with the drawback of a permanent resolution.

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