我正在设置一台电脑，配备一对 GeForce GTX 1070（均为 ASUS TURBO 1070）显卡和一台飞利浦 246E FHD 显示器，它们通过 DP（GPU-0）和 HDMI（GPU-1）连接到每个显卡。
电脑配置：
- DELL WorkStation Precision T7500（2009 年或 2010 年制造）
- 处理器：X5690*2
- 内存：16GB * 12（=192GB）
- GPU：ASUS TURBO GTX 1070 * 2（不使用 SLI 线缆）
- Ubuntu 显示管理器：gdm3
当我安装 Ubuntu 20.04 时，我检查了
- 正常安装
- 安装 Ubuntu 时下载更新
- 安装图形和 wifi 硬件的第三方软件...
我安装了 Ubuntu 20.04，然后重新启动，第二台显示器（连接到 GPU-1）不工作。
因此我按如下方式设置“NVIDIA X SERVER SETTINGS”。
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 440.82
Section "ServerLayout"
# Removed Option "Xinerama" "0"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" 1920 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection
Section "Files"
EndSection
Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
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"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Philips PHL 246E7"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 76.0
Option "DPMS"
EndSection
Section "Monitor"
Identifier "Monitor1"
VendorName "Unknown"
ModelName "Philips PHL 246E7"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 76.0
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 1070"
BusID "PCI:3:0:0"
EndSection
Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 1070"
BusID "PCI:4:0:0"
EndSection
Section "Screen"
# Removed Option "metamodes" "GPU-bb9972e4-0457-d2b7-c62f-9aa988ef66e4.GPU-0.DP-3: nvidia-auto-select +0+0 {ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}, GPU-850dc788-8ca1-f53b-5edd-54c338e6fed5.GPU-1.HDMI-1: nvidia-auto-select +1920+0 {ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}"
# Removed Option "BaseMosaic" "on"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-6"
Option "metamodes" "nvidia-auto-select +0+0 {ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}"
Option "SLI" "Off"
Option "MultiGPU" "Off"
Option "BaseMosaic" "off"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Device "Device1"
Monitor "Monitor1"
DefaultDepth 24
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-2"
Option "metamodes" "nvidia-auto-select +0+0 {ForceCompositionPipeline=On, ForceFullCompositionPipeline=On, AllowGSYNC=Off}"
Option "SLI" "Off"
Option "MultiGPU" "Off"
Option "BaseMosaic" "off"
SubSection "Display"
Depth 24
EndSubSection
EndSection
重启后，我仍然可以在一个显示器上看到 GNOME。但是，另一个显示器是黑屏，只有默认的 X 光标（右侧的光晕只是显示器上的反射）：
这是我的 nvidia-smi 信息。
Wed Aug 12 17:24:37 2020
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 440.100 Driver Version: 440.100 CUDA Version: 10.2 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 1070 Off | 00000000:03:00.0 On | N/A |
| 24% 56C P0 39W / 151W | 462MiB / 8118MiB | 1% Default |
+-------------------------------+----------------------+----------------------+
| 1 GeForce GTX 1070 Off | 00000000:04:00.0 On | N/A |
| 24% 37C P8 7W / 151W | 54MiB / 8119MiB | 11% Default |
+-------------------------------+----------------------+----------------------+
+-----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 1103 G /usr/lib/xorg/Xorg 35MiB |
| 0 1707 G /usr/lib/xorg/Xorg 206MiB |
| 0 1917 G /usr/bin/gnome-shell 121MiB |
| 0 2830 G /usr/bin/nvidia-settings 3MiB |
| 0 3201 G /usr/lib/firefox/firefox 2MiB |
| 0 3278 G /usr/lib/firefox/firefox 2MiB |
| 0 3460 G /usr/lib/firefox/firefox 2MiB |
| 0 5499 G ...094687058528,131072 --disable-features= 36MiB |
| 0 5731 G /usr/lib/firefox/firefox 2MiB |
| 0 5774 G /usr/lib/firefox/firefox 2MiB |
| 0 5830 G /usr/lib/firefox/firefox 2MiB |
| 0 7114 G /usr/lib/firefox/firefox 2MiB |
| 1 1103 G /usr/lib/xorg/Xorg 14MiB |
| 1 1707 G /usr/lib/xorg/Xorg 15MiB |
| 1 2830 G /usr/bin/nvidia-settings 0MiB |
+-----------------------------------------------------------------------------+
我检查了这些页面以供参考：
答案1
https://manpages.ubuntu.com/manpages/impish/man1/Xdmx.1.html我认为描述了解决方案和问题。在没有设置 mukti-head 代理的情况下，x 服务器上的 head 数量限制为 4 个（链接为该代理的手册）。