How to change linux text mode resolution? GRUB_GFXMODE didn't help

Question

After I set GRUB_GFXMODE it affected GRUB menu and some of subsequent printouts, but in the middle of boot, text becomes very small again and I still want to make resolution smaller.

Where else the resolution is changing during boot?

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Any usage of fbmode reports unknown mode or invalid argument:

(base) dimskraft@studebaker:~$ sudo fbset 1920x1200-32
Unknown video mode `1920x1200-32'
(base) dimskraft@studebaker:~$ sudo fbset 1920x1200
Unknown video mode `1920x1200'
(base) dimskraft@studebaker:~$ sudo fbset 640x480-60
ioctl FBIOPUT_VSCREENINFO: Invalid argument
(base) dimskraft@studebaker:~$ sudo fbset 640x480
Unknown video mode `640x480'
(base) dimskraft@studebaker:~$ sudo fbset 640x480-8
Unknown video mode `640x480-8'

and so on.

Answer 1

in the middle of boot, text becomes very small again

This is a clue: the kernel starts up in whatever firmware-supported display mode was initialized by GRUB (initially using classic VGA text mode or vesafb driver on legacy BIOS firmware, or efifb on UEFI), then it loads its own display driver (inteldrmfb, nouveau, others) and switches to a different mode.

Depending on which display driver you end up with, you might be able to use the fbset command to switch resolutions at runtime, and/or you might be able to use a kernel boot parameter like video=1920x1200-32 to set the desired non-GUI mode resolution.

Within the X11 GUI, rather than reducing the display resolution, a better approach might be to make sure the DPI value is calculated correctly, and that the system has suitable TrueType or other scalable fonts available so that it can produce fonts at arbitrary display sizes - that might be enough for the system to auto-scale the text into a reasonable size. A GUI desktop environment should also include a way to adjust the default size of text and other GUI elements to your taste.