Switch between Nvidia drivers without driver removal possible?

[linux-aarhus]

I am sorry - my apology for not understanding the issue at hand.

@SamKook

I know my system works with both the free and non-free driver once it’s installed on a drive

If the system work with both once installed - then I don’t understand the urge to make it work with the live system.

I mean - it is known that the live ISO may not be optimally configured when using the proprietary driver (only Nvidia) is an issue - perhaps (very old AMD as well) - and that you work around by using the free GPU option.

@SamKook

some apps don’t work with the non-free driver and I need that driver for some games

Exactly why I say like I do - you cannot play games on the live ISO - it is not designed for that task - the live ISO is designed for a preview of the desktop and subsequent installation.

@SamKook

Everything was working perfectly fine a few updates ago so I’m trying to get back to that state.

That may not be possible unless you create a system snap-shot before applying an update.

moving forward

When your goal is to troubleshoot your system’s GPU drivers, there is a better way.

In the topic Basic Rescue and Recovery, it has been described how you can use either TTY or kernel cmdline to reach a console without the need for a live ISO.

Using one of the described methods (see quotes below), you can reach a running system and perform tasks required.

When troubleshooting a GPU issue I suggest you start with disabling the display manager, usually sddm but there is also the new kid plasmalogin which must be installed by hand if desired, so example is for sddm.

sudo systemctl disable --now sddm

When troubleshooting, having the system booting to a console is - at any measure - to be preferred over booting a live ISO.

You can start the plasma desktop by using one of two

• startplasma-wayland
• startplasma-x11 (only available with plasma-x11-session)

When you are ready - re-enable the display manager (example sddm)

sudo systemctl enable --now sddm

@linux-aarhus

Using TTY console

If you can reach the login screen and sign in, but the desktop never shows, you may still be able to reach a console using the graphical console switching mode. This mode is using a hotkey combination of CtrlAlt and a function key.

On most systems TTY1, TTY2 and/or TTY7 is already occupied so the usable keys will be in range from F3 to F6.

To test if you can reach a TTY try one of the function keys e.g.

CtrlAltF4

The system should react by switching to a text based screen with a prompt.

Enter your credentials to login.

From there you have full system access and can perform all sorts of changes to the system.

@linux-aarhus

Using kernel cmdline

If your issue is a non-functional display-manager, e.g. gdm, sddm, lightdm, manifesting in a missing login screen, you may still be able to reach a working console without the need for mounting and chroot.

Assuming you are using the GRUB boot-loader

• press and hold the Shift key during boot until the GRUB menu shows.
• Press e on the highlighted entry
• Use arrow keys to navigate to line starting with linux
• Press the end key and add a space and the number three 3
• Press F10 to continue booting

When you are at the console prompt - enter your credentials to login.

From there you have full system access and can perform all sorts of changes to the system.