Nvidia-xconfig Not Recognizing --multigpu Option on Debian 12 (Bookworm) with NVIDIA Driver 550.120 and CUDA 12.4

Gaming and Visualization Technologies General Topics and Other SDKs GPU - Hardware
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Description:

I am trying to configure NVIDIA GPUs on my Debian 12 (Bookworm) system using nvidia-xconfig. However, when I attempt to use the --multigpu=Mosaic option, I receive an error indicating that nvidia-xconfig does not recognize the --multigpu option. The rest of the configuration works, but I cannot enable Mosaic mode or multi-GPU settings using this method.

Steps to reproduce

  1. Run the following command:
    nvidia-xconfig --device=Device0 --busid=PCI:0@22494:0:0 --allow-empty-initial-configuration --enable-all-gpus --multigpu=Mosaic
  2. Error encountered:
    nvidia-xconfig: unrecognized option: "--multigpu"
Invalid commandline, please run `nvidia-xconfig --help` for usage information.

System Information:

  • OS: Debian GNU/Linux 12 (Bookworm)
  • Kernel: 6.9.7+bpo-amd64 #1 SMP PREEMPT_DYNAMIC
  • NVIDIA Driver Version: 550.120
  • CUDA Version: 12.4
  • GPU: NVIDIA RTX 4000 Ada Generation
root@buildhost:~# nvidia-smi
Sat Oct  5 00:52:17 2024
+-----------------------------------------------------------------------------------------+
| NVIDIA-SMI 550.120                Driver Version: 550.120        CUDA Version: 12.4     |
|-----------------------------------------+------------------------+----------------------+
| 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 RTX 4000 Ada Gene...    Off |   000057DE:00:00.0 Off |                  Off |
| 30%   28C    P8              4W /  130W |      21MiB /  20475MiB |      0%      Default |
|                                         |                        |                  N/A |
+-----------------------------------------+------------------------+----------------------+

+-----------------------------------------------------------------------------------------+
| Processes:                                                                              |
|  GPU   GI   CI        PID   Type   Process name                              GPU Memory |
|        ID   ID                                                               Usage      |
|=========================================================================================|
|    0   N/A  N/A       703      G   /usr/lib/xorg/Xorg                              6MiB |
|    0   N/A  N/A      1096      G   xfwm4                                           9MiB |
+-----------------------------------------------------------------------------------------+

Troubleshooting Steps Tried:

  1. Removed --multigpu from the command. The configuration succeeded.

Actual Behavior:
nvidia-xconfig does not recognize the --multigpu option, resulting in an error.

root@buildhost:~# cat /etc/X11/xorg.conf
    # nvidia-xconfig: X configuration file generated by nvidia-xconfig
    # nvidia-xconfig:  version 550.120
    
    
    Section "ServerLayout"
        Identifier     "Layout0"
        Screen      0  "Screen0"
        InputDevice    "Keyboard0" "CoreKeyboard"
        InputDevice    "Mouse0" "CorePointer"
    EndSection
    
    Section "Files"
    EndSection
    
    Section "InputDevice"
    
        # generated from default
        Identifier     "Mouse0"
        Driver         "mouse"
        Option         "Protocol" "auto"
        Option         "Device" "/dev/psaux"
        Option         "Emulate3Buttons" "no"
        Option         "ZAxisMapping" "4 5"
    EndSection
    
    Section "InputDevice"
    
        # generated from default
        Identifier     "Keyboard0"
        Driver         "kbd"
    EndSection
    
    Section "Monitor"
        Identifier     "Monitor0"
        VendorName     "Unknown"
        ModelName      "Unknown"
        Option         "DPMS"
    EndSection
    
    Section "Device"
        Identifier     "Device0"
        Driver         "nvidia"
        VendorName     "NVIDIA Corporation"
        BoardName      "NVIDIA RTX 4000 Ada Generation"
        BusID          "PCI:0@22494:0:0"
    EndSection
    
    Section "Screen"
        Identifier     "Screen0"
        Device         "Device0"
        Monitor        "Monitor0"
        DefaultDepth    24
        Option         "AllowEmptyInitialConfiguration" "True"
        SubSection     "Display"
            Depth       24
        EndSubSection
    EndSection
2

I checked the advanced help for nvidia-xconfig using --A and found the following option:

--base-mosaic, --no-base-mosaic 
 Enable or disable the "BaseMosaic" X configuration option.

This resolved my issue.

Here is the updated result after adding this option:

nvidia-xconfig --device=Device0 --busid=PCI:1:0:0 --allow-empty-initial-configuration --enable-all-gpus --base-mosaic
----------------------------------------

Using X configuration file: "/etc/X11/xorg.conf".
Option "BaseMosaic" "True" added to Screen "Screen0".
Option "AllowEmptyInitialConfiguration" "True" added to Screen "Screen0".
Backed up file '/etc/X11/xorg.conf' as '/etc/X11/xorg.conf.backup'
New X configuration file written to '/etc/X11/xorg.conf'
----------------------------------------

Here is the content of the updated /etc/X11/xorg.conf file:
root@DEB-HPZ1G9To-4CE423BT3J:~# cat /etc/X11/xorg.conf

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 550.135


Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"

    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "NVIDIA GeForce RTX 4060"
    BusID          "PCI:1:0:0"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "BaseMosaic" "True"
    Option         "AllowEmptyInitialConfiguration" "True"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

I’m sorry, but I’m new to this.

Is this the correct approach to fix the issue?
The actual error was related to the --multigpu=Mosaic option, which is not recognized by nvidia-xconfig.