Unable to activate SLI - Dual GTX880M

Graphics / Linux Linux
1

nvidia-bug-report.shnvidia-bug-report.log (398.7 KB)

Hi all,

I have an Alienware MX18 with Dual GTX 880M and I’m unable to activate SLI.
With windows I never had issue before, so I guess it’s only a configuration issue. Unfortunately It still doesn’t work.

So I take a look on google and I discover I should use something like:

nvidia-xconfig --enable-all-gpus --only-one-x-screen  --busid=PCI:1:0:0 --sli=AA

But not really convincing even after testing different values then reboot …

Here a copy of my /etc/X11/xorg.conf generated file

Code:

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 440.82

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      "GeForce GTX 880M"
    BusID          "PCI:1:0:0"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "SLI" "AA"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

In first place there was no xorg.conf file at this location. Does this file location is the right one or Pop!_OS uses xorg.conf from another place ?

Screenshot from 2020-06-04 11-12-52.png

01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GK104M [GeForce GTX 880M] [10de:1198] (rev a1) (prog-if 00 [VGA controller])
07:00.0 3D controller [0302]: NVIDIA Corporation GK104M [GeForce GTX 880M] [10de:1198] (rev a1)

+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.82       Driver Version: 440.82       CUDA Version: 10.2     |
|-------------------------------+----------------------+----------------------+
|   0  GeForce GTX 880M    Off  | 00000000:01:00.0 N/A |                  N/A |
| N/A   55C    P0    N/A /  N/A |    358MiB /  8110MiB |     N/A      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 880M    Off  | 00000000:07:00.0 N/A |                  N/A |
| N/A   48C    P8    N/A /  N/A |      0MiB /  8111MiB |     N/A      Default |
+-------------------------------+----------------------+----------------------+

with lspci -t

-[0000:00]-+-00.0
           +-01.0-[01-06]--+-00.0
           |               \-00.1
           +-01.1-[07]----00.0
           +-14.0
           +-16.0
           +-1a.0
           +-1b.0
           +-1c.0-[08]--
           +-1c.2-[09]----00.0
           +-1c.3-[0a]--+-00.0
           |            \-00.1
           +-1c.4-[0b]----00.0
           +-1d.0
           +-1f.0
           +-1f.2
           \-1f.3

Thank you for your help.

2

Please run nvidia-bug-report.sh as root and attach the resulting nvidia-bug-report.log.gz file to your post. You will have to rename the file ending to something else since the forum software doesn’t accept .gz files (nifty!).

3

I missed this part. I added it

4

First of all, I can’t really recommend to use SLI on Linux at all. Furthermore, mobile gpus are not supported so I don’t know if this works on your system at all.
Currently, you’re getting:

[    11.584] (EE) NVIDIA(GPU-0): Failed to find a valid SLI configuration.
[    11.584] (EE) NVIDIA(GPU-0): Invalid SLI configuration 1 of 1:
[    11.584] (EE) NVIDIA(GPU-0): GPUs:
[    11.584] (EE) NVIDIA(GPU-0):     1) NVIDIA GPU at PCI:1:0:0
[    11.585] (EE) NVIDIA(GPU-0):     2) NVIDIA GPU at PCI:7:0:0
[    11.585] (EE) NVIDIA(GPU-0): Errors:
[    11.585] (EE) NVIDIA(GPU-0):     - Unknown error

‘Unknown Error’ doesn’t really help.
In general, drm modesetting has to be disabled for SLI:
run

grep nvidia /etc/modprobe.d/* /lib/modprobe.d/*

to find a file containing

options nvidia-drm modeset=1

and change 1 to 0
then run

sudo update-initramfs -u

and reboot.
Also, just use a minimal xorg.conf just containing a device section:

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce GTX 880M"
    BusID          "PCI:1:0:0"
    Option         "SLI" "on"
EndSection

Then check /var/log/Xorg.0.log if it works.

5

Hi generix,

Thank you for your answer.
You say you can’t recommend to use SLI on Linux, why ?
You also say mobile gpus aren’t supported. You mean in forum, with linux or generally speaking ? Because it was working with windows drivers.
Whatever, I tried according your advices.
Good news is my computer still working :) the bad news is it changes nothing. [nvidia-bug-report.log|attachment][upload://9qbhHRTaaD9VBkbuESH2U92bbBo.log) (407.2 KB)

Linux is useful for my day to day activity. But even blender 3d don’t recognize my graphic cards, as few games I play …

6

Why SLI is outdated in general:
https://developer.nvidia.com/explicit-multi-gpu-programming-directx-12
Hint:NVApi doesn’t exist on Linux.
Furthermore, it’s mostly broken on Linux.

According to the manual
https://download.nvidia.com/XFree86/Linux-x86_64/440.64/README/sli.html
SLI on mobile chips with the Linux driver is not supported, i.e. likely doesn’t work.

1 Like
7

SLI on mobile chips with the Linux driver is not supported, i.e. likely doesn’t work.

I’m a bit surprised about that, chipsets on mobile cards aren’t exactly the same than on desktop card ?

I found this post: https://www.nvidia.com/en-us/geforce/forums/game-ready-drivers/13/253648/no-sli-on-linux-for-mobile-gpus-wtf-nvidia/
So how incredible it sounds, there is no SLI support for mobile GPU … … … … …