Arch Linux

jbhall

Member

Registered: 2021-03-11

Posts: 18

XOrg Multihead Configuration with Multiple GPUs

I've been trying for days to get this figured out, but can't seem to get to the bottom of it.

I recently installed an extra, non-matching, non-sli enabled card to my rig for GPU processing power when needed. My dual monitor setup works alright, except that it is treating the whole space as one monitor and being wonky about it. I understand that the whole point of Xinerama and TwinView is to treat it as one big screen, however, in my case, it's causing weird behavior.

I have two 2560x1440 monitors. The one on the right is flipped to be vertical. With the current configuration, it's as if XOrg views the screen as 2560x2560 the way it's setting wallpapers. And no matter what I do, I can't seem to be able to set an individual wallpaper per monitor. It just won't work. No matter the options I pass, the background is set across both monitors. I've tried feh, hsetroot, xsetroot, and even nitrogen. None of them can seem to differentiate between the two monitors while setting background...

If it helps any, hsetroot returns this as an error:

Xlib:  extension "XINERAMA" missing on display ":0".

X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  130 (MIT-SHM)
  Minor opcode of failed request:  3 (X_ShmPutImage)
  Serial number of failed request:  33
  Current serial number in output stream:  34

To be transparent, I've tried enabling XINERAMA, and it breaks everything. I'm assuming because it's incompatible with nvidia, maybe? I've also tried setting up TwinView to no avail.

Here's my config:

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" RightOf "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
    #Option         "Xinerama" "1"
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     "DP-2"
    Modeline      "2560x1440_60.00" 311.83 2560 2744 3024 3488 1440 1441 1444 1490 -HSync +Vsync
    Option         "PreferredMode" "2560x1440_60.00"
    Option         "Primary" "true"
    Option         "LeftOf" "DP-0"
    Option         "DPMS"
EndSection

Section "Monitor"
    Identifier     "DP-0"
    Modeline      "1440x2560_60.00" 311.83 1440 1441 1444 1490 2560 2744 3024 3488 -HSync +Vsync
    Option         "PreferredMode" "1440x2560_60.00"
    Option         "RightOf" "DP-1"
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "RTX3080"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce RTX 3080"
    BusID          "PCI:9:0:0"
    Option         "Coolbits" "31"
EndSection

Section "Device"
    Identifier     "RTX2070SUPER"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce RTX 2070 SUPER"
    BusID          "PCI:10:0:0"
    Option         "Coolbits" "31"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "RTX3080"
    Monitor        "DP-2"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "RTX2070SUPER"
    Monitor        "DP-0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Please bare in mind that this is the config I've arrived at after a week of trial and error, so I understand there may be some odd configs in here.

Anyway, if I set both Screens to use the same device (i.e. both use RTX3080), then the screens and wallpapers behave exactly how I expect them to. However, the coolbits option for RTX2070SUPER then doesn't work. I can't do any overclocking or manually control the fans when I set both screens to use the same device.

I'm at a loss here. How do I get it to behave properly? When I write behave properly, I mean recognize the screens properly, allow me to set backgrounds for each individual monitor, and also allow overclocking/fan control???

Last edited by jbhall (2021-03-11 06:31:27)

jbhall

Member

Registered: 2021-03-11

Posts: 18

Re: XOrg Multihead Configuration with Multiple GPUs

Well at this point, I've given up and just use backgrounds that I crop to 4000x2560... Still having some bugs, though, like XINERAMA missing on display ":0".