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rep_movsd

Member

Registered: 2013-08-24

Posts: 133

Avoiding multiple video mode switches on boot

I have a general technical question that perhaps someone more knowledgeable may be able to solve

So back in the old days, you switched to a graphics mode by a BIOS call and the set of "official" modes was fixed and standardized
Game devs used to program the VGA registers directly - it was mostly a matter of setting the RAMDAC timings, the colordepth and the pixel format

In modern times things seem so much more complex - I notice the following on my system

1) The BIOS POST has set some mode and shows a logo until GRUB comes up
2) GRUB switches to its mode and loads the menu (Mode switch 1)
3) Kernel starts off and shows the initial boot process - looks like a text mode with flashing cursor - not the same mode as grub showed (Mode switch 2)
4) Kernel switches to graphical mode due to KMS (nvidia_drm.modeset=1)  (Mode switch 3)
5) The kernel switches back to TTY1 where the X log is seen very briefly, causing another brief mode switch - On Nvidia drivers, switching to the TTY seems to switch modes (as opposed to nouveau where the TTYs are all in the same mode as the X video mode  (Mode switch 4)
7) That initial TTY switches instantly back to the window manager and the GUI shows up (Mode switch 5)

Is it possible to streamline this and prevent the time consuming flickery multiple switches?

Can we setup the system such that
1) GRUB uses whatever mode the EFI bios had set
2) Kernel uses the same mode
3) Kernel switches the root TTY to desired GUI mode
4) Display driver takes that mode as is and goes to the GUI

I have a feeling this is more to do with how propreitary drivers like nvidia behave.

I'm sure there is a way to do this or at least get rid of a couple of mode switches in the boot - any pointers?

Thanks in advance

Lone_Wolf

Forum Moderator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 11,920

Re: Avoiding multiple video mode switches on boot

mode switch 5 is due to nvidia proprietary driver not providing a framebuffer driver for KMS as the kernel drivers do.

Many efi firmwares have an option to boot in full HD resolution, I'm using that with Refind to get one mode switch less.

Verify if your efi firmware has that option set, then try to convince grub not to change modes.

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Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)