Hyper-V, Linux, Windows

Linux: Prevent X11/Xorg from using a (Nvidia) GPU

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Hi,

when you install an NVidia GPU to run HPC tasks you usually don’t want that X11/xorg use it. This can be done by force Xorg to use the framebuffer device and prevent the nvidia_drm driver from creating a framebuffer device.
You can check this by nvidia-smi

root@debdev ~ # nvidia-smi 
+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|    0   N/A  N/A      1581      G   /usr/lib/xorg/Xorg                          167MiB |
|    0   N/A  N/A      1713      G   /usr/bin/gnome-shell                         16MiB |
+---------------------------------------------------------------------------------------+

These are the tasks to install the nvidia drivers (Tested with Ubuntu 22.04 LTS on Hyper-V)

I use Hyper-V so I installed an optimized kernel. Omit this if you are not on Hyper-V.

michael@debdev ~ # sudo su
root@debdev ~ # apt update
root@debdev ~ # apt install linux-azure

Reboot, check kernel version and remove no longer used packages

root@debdev ~ # uname -a 
... 6.5.0-1015-azure #15~22.04.1-Ubuntu SMP ..
root@debdev ~ # apt autoremove

Install build tools and kernel header

root@debdev ~ # apt install build-essential
root@debdev ~ # apt install linux-headers-$(uname -r )

Configure NVidia package sources. Remove the old nvidia siging key,

root@debdev ~ # wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2204/x86_64/cuda-ubuntu2204.pin
root@debdev ~ # mv cuda-ubuntu2204.pin /etc/apt/preferences.d/cuda-repository-pin-600
root@debdev ~ # wget https://developer.download.nvidia.com/compute/cuda/12.3.2/local_installers/cuda-repo-ubuntu2204-12-3-local_12.3.2-545.23.08-1_amd64.deb
root@debdev ~ # dpkg -i cuda-repo-ubuntu2204-12-3-local_12.3.2-545.23.08-1_amd64.deb
root@debdev ~ # cp /var/cuda-repo-ubuntu2204-12-3-local/cuda-*-keyring.gpg /usr/share/keyrings/
root@debdev ~ # apt-get update
root@debdev ~ # apt-key del 7fa2af80

Install the nvidia drivers.

There are 2 options:
– The open drivers
– The legacy drivers

Open drivers: To install the open driver (remove already istalled legacy drivers before):

root@debdev ~ # apt-get --purge remove nvidia-kernel-source-545
root@debdev ~ # apt-get install -y nvidia-kernel-open-545
root@debdev ~ # apt-get install -y cuda-drivers-545

Legeacy drivers: If installed remove the open drivers and install the legeacy drivers (check the installed version. In this case 545):

root@debdev ~ # apt-get remove --purge nvidia-kernel-open-545
root@debdev ~ # apt-get install -y cuda-drivers

Disable creating a nvidia fb device

root@debdev ~ # modinfo nvidia_drm
...
parm:           fbdev:Create a framebuffer device
...

Edit /etc/default/grub

root@debdev ~ # vi /etc/default/grub

and append 

nvidia_drm.fbdev=0

to the GRUB_CMDLINE_LINUX_DEFAULT parameter. For example

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nvidia_drm.fbdev=0"

Update grub and initfs

root@debdev ~ # update-grub
root@debdev ~ # update-initramfs -v -u -k $(uname -r)

Force Xorg/X11 to use the framebuffer device. Create a file /etc/X11/xorg.conf.d/fb.conf

Section "Device"
    Identifier "FBDEV"
    Driver "fbdev"
    Option "fbdev" "/dev/fb0"
    Option      "AutoAddDevices" "false"
    Option      "AutoAddGPU" "false"
EndSection

and restart the restart gdm

root@debdev ~ # systemctl stop gdm3

Check if any processes are running on the GPU

root@debdev ~ # nvidia-smi
Tue Mar  4 22:47:26 2024
+---------------------------------------------------------------------------------------+
| NVIDIA-SMI 545.23.08              Driver Version: 545.23.08    CUDA Version: 12.3     |
|-----------------------------------------+----------------------+----------------------+
| 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 L40                     On  | 0000AF52:00:00.0 Off |                    0 |
| N/A   26C    P8              21W / 300W |      4MiB / 46068MiB |      0%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+

+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|  No running processes found                                                           |
+---------------------------------------------------------------------------------------+

Michael

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