SDDM and AMD + NVIDIA GPU

English Install/Boot/Login
21

@Shortwave8115
Not now, i have GDM as default to be able to answer to you.
You can see what i have for the moment (i will change to sddm and will use `systemd.unit=multi-user.target)

lorraine@llinux:~> sudo update-alternatives --config default-displaymanager
[sudo] Mot de passe de root : 
There are 4 choices for the alternative default-displaymanager (providing /usr/lib/X11/displaymanagers/default-displaymanager).

  Selection    Path                                  Priority   Status
------------------------------------------------------------
  0            /usr/lib/X11/displaymanagers/gdm       25        auto mode
  1            /usr/lib/X11/displaymanagers/console   5         manual mode
* 2            /usr/lib/X11/displaymanagers/gdm       25        manual mode
  3            /usr/lib/X11/displaymanagers/sddm      25        manual mode
  4            /usr/lib/X11/displaymanagers/xdm       10        manual mode

Press <enter> to keep the current choice[*], or type selection number:

Do you really se the output from systemctl show display-manager.service ? there are more than 70 lines !

I will try now with systemd.unit=multi-user.targetat boot.

22

To the OP. Which SDDM is installed, could be there is a conflict.
There are two versions of SDDM in tumbleweed. I got into that problem before.

Verify by using

zypper se SDDM

Mine with a working SDDM looks like this:

~> zypper se SDDM
Loading repository data...
Reading installed packages...

S  | Name                        | Summary                             | Type
---+-----------------------------+-------------------------------------+--------
   | kalpa-themes-sddm           | SDDM Light/Dark themes for Kalpa    | package
i  | plasma6-sddm-theme-openSUSE | SDDM theme for openSUSE             | package
   | sddm                        | QML-based display manager (Qt5)     | package
i  | sddm-branding-openSUSE      | openSUSE branding for SDDM (Qt5)    | package
i+ | sddm-conf                   | SDDM configuration editor           | package
   | sddm-conf-lang              | Translations for package sddm-conf  | package
   | sddm-config-wayland         | Config to let SDDM run using wayl-> | package
i  | sddm-greeter-qt5            | SDDM Greeter for Qt5 themes         | package
i  | sddm-greeter-qt6            | SDDM Greeter for Qt6 themes         | package
i+ | sddm-kcm6                   | A sddm control module for KDE       | package
   | sddm-kcm6-lang              | Translations for package sddm-kcm6  | package
i+ | sddm-qt6                    | QML-based display manager (Qt6)     | package
i  | sddm-qt6-branding-openSUSE  | Plasma 6 branding for SDDM          | package
   | sddm-wayland-miriway        | Miriway SDDM greeter configuration  | package
23

@Shortwave8115

That’s crazy!!!

I rebooted (the BIOS was in DYNAMIC display mode), and I added “systemd.unit=multi-user.target” to the boot command line.

I logged in as the “lorraine” user, then ran the command “sudo systemctl start sddm” and… I saw the login screen and logged into KDE.

Now, we know that:

  1. SDDM doesn’t start properly when simply booting (black screen + mouse)

  2. SDDM starts correctly when running the command “sudo systemctl start sddm”

But what’s the problem?

24

Not sure, what does journal and dmesg say?

25

@conram

Here is mine :

lorraine@llinux:~> sudo zypper se SDDM
[sudo] Mot de passe de root : 
Rafraichissement du service 'NVIDIA'.
Rafraichissement du service 'openSUSE'.
Chargement des données du dépôt...
Lecture des paquets installés...

S  | Name                        | Summary                              | Type
---+-----------------------------+--------------------------------------+-------
   | kalpa-themes-sddm           | SDDM Light/Dark themes for Kalpa     | paquet
i  | plasma6-sddm-theme-openSUSE | SDDM theme for openSUSE              | paquet
   | sddm                        | QML-based display manager (Qt5)      | paquet
i  | sddm-branding-openSUSE      | openSUSE branding for SDDM (Qt5)     | paquet
i+ | sddm-conf                   | SDDM configuration editor            | paquet
i+ | sddm-conf-lang              | Translations for package sddm-conf   | paquet
   | sddm-config-wayland         | Config to let SDDM run using wayland | paquet
   | sddm-greeter-qt5            | SDDM Greeter for Qt5 themes          | paquet
i  | sddm-greeter-qt6            | SDDM Greeter for Qt6 themes          | paquet
i  | sddm-kcm6                   | A sddm control module for KDE        | paquet
i  | sddm-kcm6-lang              | Translations for package sddm-kcm6   | paquet
i  | sddm-qt6                    | QML-based display manager (Qt6)      | paquet
i  | sddm-qt6-branding-openSUSE  | Plasma 6 branding for SDDM           | paquet
   | sddm-wayland-miriway        | Miriway SDDM greeter configuration   | paquet
lorraine@llinux:~>
26

@conram
The only difference is an “i” pn the line dddm-greeter-dt5 in yours

27

Yours looks good. I am using nvidia also the igpu is disabled in the bios.

28

@conram
I had make this before but this option use more energy.
I will use the Nvidia card only for game

29

@Shortwave8115

journal say :

sept. 10 22:53:08 llinux systemd[1]: Starting Cleanup of Temporary Directories...
sept. 10 22:53:08 llinux systemd[1]: systemd-tmpfiles-clean.service: Deactivated successfully.
sept. 10 22:53:08 llinux systemd[1]: Finished Cleanup of Temporary Directories.
sept. 10 22:57:43 llinux sudo[5197]: pam_kwallet5(sudo:auth): pam_kwallet5: pam_sm_authenticate
sept. 10 22:57:43 llinux sudo[5197]: pam_kwallet5(sudo:auth): pam_kwallet5: Refusing to do anything for the root user
sept. 10 22:57:49 llinux sudo[5197]: lorraine : TTY=pts/0 ; PWD=/home/lorraine ; USER=root ; COMMAND=/usr/bin/journalctl -f
sept. 10 22:57:49 llinux sudo[5197]: pam_kwallet5(sudo:setcred): pam_kwallet5: pam_sm_setcred
sept. 10 22:57:49 llinux sudo[5197]: pam_unix(sudo:session): session opened for user root(uid=0) by lorraine(uid=1000)
sept. 10 22:57:49 llinux sudo[5197]: pam_kwallet5(sudo:session): pam_kwallet5: pam_sm_open_session
sept. 10 22:57:49 llinux sudo[5197]: pam_kwallet5(sudo:session): pam_kwallet5: we were already executed

For dmesg -w, it’s a very long file with 1424 lines : what do i read ?

30

Whatever the last lines are before you hit the black screen issue

31

And now here the output from 2 commands :

lorraine@llinux:~> sudo systemctl status switcheroo-control.service
[sudo] Mot de passe de root : 
○ switcheroo-control.service - Switcheroo Control Proxy service
     Loaded: loaded (/usr/lib/systemd/system/switcheroo-control.service; enabled; preset: enabled)
     Active: inactive (dead)
lorraine@llinux:~> sudo switcherooctl list
lorraine@llinux:~>

And i can’t see in KDE what i have in Gnome.
In Gnome, when clicking right on the game “tuxrace”, i have the option to use the dGPU Nvidia.

In KDE, when clicking right on the same game, i have no option for choice the dGPU.

The question is : what i’m using ? AMD or Nvidia ?

32

See post #2 above.
Also, nvidia-smi shows what is actually running on the Nvidia.

33

@OrsoBruno

I’m logged with DYNAMIC in the bios and the result of nvidia-smi is :

lorraine@llinux:~> nvidia-smi
Fri Sep 11 11:50:43 2026       
+-----------------------------------------------------------------------------------------+
| NVIDIA-SMI 595.99.02              Driver Version: 595.99.02      CUDA Version: 13.2     |
+-----------------------------------------+------------------------+----------------------+
| GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
| Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
|                                         |                        |               MIG M. |
|=========================================+========================+======================|
|   0  NVIDIA GeForce RTX 5070 ...    On  |   00000000:01:00.0 Off |                  N/A |
| N/A   38C    P8              4W /   47W |      54MiB /   8151MiB |      0%      Default |
|                                         |                        |                  N/A |
+-----------------------------------------+------------------------+----------------------+

+-----------------------------------------------------------------------------------------+
| Processes:                                                                              |
|  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
|        ID   ID                                                               Usage      |
|=========================================================================================|
|    0   N/A  N/A            1462      G   /usr/bin/Xorg.bin                         4MiB |
|    0   N/A  N/A            1698    C+G   /usr/bin/kwin_wayland                     7MiB |
+-----------------------------------------------------------------------------------------+
lorraine@llinux:~>

So I guess that in KDE, my Nvidia graphics card is being used, when it should be the AMD one.

And that’s yet another problem. It’s so discouraging!

34

@OrsoBruno

A user from KDE Discuss says it’s better to user CUDA 610 or 615 driver and add nvidia-drm.modeset=1 and if don’t work try adding in addition initcall_blacklist=sysfb_init.

Perhaps it’s a good idea to change my actual driver but not for the rest.
This seems say Nvidia must be running, not an AMD GPU.

What do ypu think about this ?
And could you give me the way for :

  • uninstall Nvidia 07
  • cancel the repo Nvidia
  • install the repo CUDA
  • install Nvidia 615 or 610
  • how to know what is the good driver for me (NVIVIA GeForce RTX 5070)
35

As I see it, that is in the nature of “Dynamic”, some processes do use the discrete GPU when the system sees fit. The actual usage is 0%, meaning that the GPU is likely used with a very low duty cycle and the power at 4W is less than 8% of maximum…
Try to explicitly launch some heavy app on the Nvidia and see what changes.
You may also have a better view installing nvtop which should show what GPU each running process is actually using.

36

The “stable” branch for RTX5070 is still 595.99, the “New Feature” branches (610, 615) are for developers and early adopters.
I think your system is working and you may not wish to go down other rabbit holes with still beta drivers, but if you feel different @malcolmlewis should be able to advise better.

37

@OrsoBruno @malcolmlewis

No, I’ll take your sound advice: I’ll stay reasonable.

Here’s my nvtop output. And I haven’t enabled the “dedicated card” option.

Capture d'écran_20260911_130228
Capture d'écran_20260911_130228891×692 66.4 KB

So I conclude that it is indeed my Nvidia card that’s running on KDE, while the AMD GPU is being used by GNOME.

So there’s an anomaly somewhere.

Here first, ExtremeTuxracer with dedicated graphics card

Capture d'écran_20260911_131741
Capture d'écran_20260911_1317411711×691 259 KB

Here, the same game without dedicated graphics card

Capture d'écran_20260911_132041
Capture d'écran_20260911_1320411684×699 238 KB

38

@OrsoBruno

Extreme Tuxracer appears allways “both” with or without dedicated graphic card
Capture d'écran_20260911_133653

39

Both G+C means GPU+CPU…

40

@hui

It’s why i think a problem exists. But where ?