How to change Grub menu resolution?

General support questions
targettor
Posts: 1
Joined: 2017/11/15 19:42:22

Re: How to change Grub menu resolution?

Post by targettor » 2017/11/15 20:30:53

The suggested solutions above did not solve my problem, but they helped me to find a solution.

The following fixed the issue for me:

/etc/default/grub:
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=root/root rd.lvm.lv=root/swap
vga=884"
GRUB_CMDLINE_LINUX_DEFAULT="video=1600x1200"

GRUB_DISABLE_RECOVERY="true"
GRUB_GFXMODE=1600x1200x16
GRUB_GFXPAYLOAD_LINUX=keep


And activate with:
grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg (if you're using a UEFI BIOS and a GPT system disk)

I am as well using a KVM switch between computer and display. My EIZO display (FlexScan S2410W) is connected through analog DVI-I.
This setup actually stops the computer from autodetecting the display's capabilities, which is very unusual nowadays.
I am using CentOS 7.4 in console-only mode. There is no xorg.conf, which makes the issue even more difficult.

It would be better if Red Hat used very conservative display settings when they cannot be auto-detected, just to avoid problems, but unfortunately, they don't.

The problem is actually not with the resolution, but with the horizontal/vertical refresh rate. In my case, it is out of range, which causes my display go blank. In other cases, like in lgorek24's, the odd refresh frequency causes the display to shift contents off totally. I also had this in earlier releases (both Windows and Linux).

However when trying out different resolutions in CentOS, this also seems to inherently affect the refresh rate (as if there are profiles consisting of resolution + refresh rates). Trying out different resolutions randomly helped to fix the issue with incorrect refresh frequencies.

I also remember adding the "vesa" option to the kernel options during boot time from the installation USB stick (hitting the "e" key and Ctrl+x after the change). If no resolution helps, you may wanna try this out as well.

I assume that most people working with a KVM setup are going to work over SSH and X11Forwarding anyway, and not directly on the system. A low-granular display resolution should suffice as a fallback.

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