Problem with 2xT1000 base Mosaic mode

Graphics / Linux Linux
1

Good afternoon!
I have problems with 2 Nvidia cards T1000 with base mosaic mode. Checked a lot of information but it didn’t help.

OS: Xubuntu 20.04
kernel: 5.15.0-75-generic
CPU: Intel(R) Core™ i7-7700K CPU @ 4.20GHz
Nvidia driver: Installed CUDA version 11.7 driver 515.43.04

sudo cat /sys/module/nvidia_drm/parameters/modeset return ‘N’

I tried a lot of combinations in pci slots not working. Checked cards - they works.
Two cards inserted in PC.

  1. If no xorg.conf file and only 1 display connected to card1 system loads correctly.

  2. If no xorg.conf file and i connect display to card2 in nvidia-settings i saw that display connect but it missed after few seconds. lately it shows again. And so on. In Xorg0.log i saw
    [ 315.420] randr: failed to create shared pixmap
    [ 315.420] (EE) NVIDIA(G0): Failed to configure Reverse PRIME on output DP-1-3.

  3. When 2 displays connected to others cards and I setup xorg.conf file I get black screen.
    Example
    Section “Device”
    Identifier “Device0”
    Driver “nvidia”
    VendorName “NVIDIA Corporation”
    BoardName “NVIDIA T1000 8GB”
    BusID “PCI:1:0:0”
    EndSection

Section “Device”
Identifier “Device1”
Driver “nvidia”
VendorName “NVIDIA Corporation”
BoardName “NVIDIA T1000 8GB”
BusID “PCI:2:0:0”
EndSection

Section “Screen”
Identifier “Screen0”
Device “Device0”
Monitor “Monitor0”
DefaultDepth 24
Option “Stereo” “0”
Option “nvidiaXineramaInfoOrder” “DFP-0”
Option “metamodes” “GPU-0.DP-2: 1920x1080_60 +0+0, GPU-1.DP-3: 1920x1080_60 +0+0”
Option “MultiGPU” “Off”
Option “SLI” “Mosaic”
Option “BaseMosaic” “on”
Option “UseHotplugEvents” “true”
Option “AllowEmptyInitialConfiguration” “True”
SubSection “Display”
Depth 24
EndSubSection
EndSection

I tried in many combinations: BaseMosaic on, Sli off|Mosaic, MultiGPU on|off but it didn’t help.
Tried to set kernel parameter iommu=off as you advice in previous ticket, it is didn’t help.

xrandr --listproviders returns
Providers: number : 3
Provider 0: id: 0x218 cap: 0x1, Source Output crtcs: 4 outputs: 8 associated providers: 2 name:NVIDIA-0
Provider 1: id: 0x44d cap: 0x6, Sink Output, Source Offload crtcs: 3 outputs: 4 associated providers: 1 name:modesetting
Provider 2: id: 0x41a cap: 0x2, Sink Output crtcs: 4 outputs: 8 associated providers: 1 name:NVIDIA-G0

Try to use xubuntu 22.04 here some problem BUT I can load system when i remove xserver-xorg-video-amdgpu packet. But other problems was.

I don’t understand root of the problem. Hope you will help me. Thank you.