我买了一台笔记本电脑，它在“Optimus”类型的设置中集成了英特尔显卡和独立的 nVidia GPU。集成显卡通常都很好，但笔记本电脑的 HDMI 和 DisplayPort 端口仅物理连接到 nVidia 芯片。
经过一些实验，我确实让 PRIME 在每个应用程序的基础上工作输出到内置显示器，似乎libglvnd是多 GPU 渲染的未来，所以我将我的 Gentoo 系统更新到 Xorg 1.20.8、Linux 5.7.8 和 nvidia-drivers 440.82-r3，并启用了 libglvnd 支持。
我没有明确的规定xorg.conf，并且允许自动检测和配置运行。
xrandr --listproviders显示两张卡都被检测到并注册，但我没有看到任何“接收器”或我可以使用xrandr（1.5.1）选择的其他项目：
Providers: number : 2
Provider 0: id: 0x45 cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 4 outputs: 2 associated providers: 0 name:Intel
Provider 1: id: 0x220 cap: 0x0 crtcs: 0 outputs: 0 associated providers: 0 name:NVIDIA-G0
并且xrandr -q仅显示英特尔输出：
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 340mm x 190mm
1920x1080 120.11*+ 48.08
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
Xorg 日志（下面的完整启动日志）显示，当我插拔电缆时，nVidia 驱动程序正在报告图形端口上的热插拔事件。
[272668.092] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): connected
[272668.093] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): Internal DisplayPort
[272668.093] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): 2660.0 MHz maximum pixel clock
[272668.093] (--) NVIDIA(GPU-0):
[272670.384] (--) NVIDIA(GPU-0): HYO HDMI (DFP-0): connected
[272670.384] (--) NVIDIA(GPU-0): HYO HDMI (DFP-0): Internal TMDS
[272670.384] (--) NVIDIA(GPU-0): HYO HDMI (DFP-0): 600.0 MHz maximum pixel clock
据我了解，核心 libglvnd 设置似乎工作正常，但我无法确定如何切换到 nVidia GPU，以便我可以使用我的输出端口。在试验早期的 PRIME 模型时，需要使用诸如DRI_PRIME或__GL*之类的环境变量，但我strings在 libglvnd 二进制文件上使用并没有发现任何有希望的东西，并且 libglvnd 包没有附带任何类似于optirun.
一旦检测到我的多 GPU 设置并正确报告热插拔事件，如何使用 libglvnd 激活 dGPU 以便可以使用我的外部显示器端口？
Xorg 启动时删除了输入设备以适应限制：
[ 25.679] (--) Log file renamed from "/var/log/Xorg.pid-5923.log" to "/var/log/Xorg.0.log"
[ 25.680]
X.Org X Server 1.20.8
X Protocol Version 11, Revision 0
[ 25.680] Build Operating System: Linux 5.5.3-gentoo-x86_64 x86_64 Gentoo
[ 25.680] Current Operating System: Linux codex 5.7.2-gentoo-x86_64 #3 SMP PREEMPT Thu Jun 18 16:11:45 CDT 2020 x86_64
[ 25.680] Kernel command line: BOOT_IMAGE=/vmlinuz-5.7.2-gentoo-x86_64 root=/dev/mapper/codex-root ro dolvm crypt_root=PARTUUID=4171a9c1-510e-40f1-a4cc-01162e222522 root=/dev/codex/root resume=/dev/codex/swap root_trim=yes
[ 25.680] Build Date: 16 June 2020 07:48:52PM
[ 25.680]
[ 25.680] Current version of pixman: 0.38.4
[ 25.680] Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
[ 25.680] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 25.680] (==) Log file: "/var/log/Xorg.0.log", Time: Thu Jun 18 16:14:54 2020
[ 25.681] (==) Using config directory: "/etc/X11/xorg.conf.d"
[ 25.681] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 25.682] (==) ServerLayout "layout"
[ 25.682] (==) No screen section available. Using defaults.
[ 25.682] (**) |-->Screen "Default Screen Section" (0)
[ 25.682] (**) | |-->Monitor "<default monitor>"
[ 25.683] (==) No monitor specified for screen "Default Screen Section".
Using a default monitor configuration.
[ 25.683] (==) Automatically adding devices
[ 25.683] (==) Automatically enabling devices
[ 25.683] (==) Automatically adding GPU devices
[ 25.683] (==) Max clients allowed: 256, resource mask: 0x1fffff
[ 25.684] (WW) The directory "/usr/share/fonts/TTF/" does not exist.
[ 25.684] Entry deleted from font path.
[ 25.684] (WW) The directory "/usr/share/fonts/OTF/" does not exist.
[ 25.684] Entry deleted from font path.
[ 25.684] (WW) The directory "/usr/share/fonts/Type1/" does not exist.
[ 25.684] Entry deleted from font path.
[ 25.684] (WW) `fonts.dir' not found (or not valid) in "/usr/share/fonts/100dpi/".
[ 25.684] Entry deleted from font path.
[ 25.684] (Run 'mkfontdir' on "/usr/share/fonts/100dpi/").
[ 25.684] (WW) `fonts.dir' not found (or not valid) in "/usr/share/fonts/75dpi/".
[ 25.684] Entry deleted from font path.
[ 25.684] (Run 'mkfontdir' on "/usr/share/fonts/75dpi/").
[ 25.684] (==) FontPath set to:
/usr/share/fonts/misc/
[ 25.684] (**) ModulePath set to "/usr/lib64/xorg/modules"
[ 25.684] (II) The server relies on udev to provide the list of input devices.
If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 25.684] (II) Loader magic: 0x561eb766cd20
[ 25.684] (II) Module ABI versions:
[ 25.684] X.Org ANSI C Emulation: 0.4
[ 25.684] X.Org Video Driver: 24.1
[ 25.684] X.Org XInput driver : 24.1
[ 25.684] X.Org Server Extension : 10.0
[ 25.685] (++) using VT number 7
[ 25.685] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, disabling logind integration
[ 25.685] (II) xfree86: Adding drm device (/dev/dri/card1)
[ 25.685] (II) xfree86: Adding drm device (/dev/dri/card0)
[ 25.691] (--) PCI:*(0@0:2:0) 8086:3e9b:1462:129b rev 2, Mem @ 0xa3000000/16777216, 0x80000000/268435456, I/O @ 0x00005000/64, BIOS @ 0x????????/131072
[ 25.691] (--) PCI: (1@0:0:0) 10de:2191:1462:129b rev 161, Mem @ 0xa4000000/16777216, 0x90000000/268435456, 0xa0000000/33554432, I/O @ 0x00004000/128, BIOS @ 0x????????/524288
[ 25.691] (II) LoadModule: "glx"
[ 25.691] (II) Loading /usr/lib64/xorg/modules/extensions/libglx.so
[ 25.699] (II) Module glx: vendor="X.Org Foundation"
[ 25.699] compiled for 1.20.8, module version = 1.0.0
[ 25.699] ABI class: X.Org Server Extension, version 10.0
[ 25.699] (II) Applying OutputClass "nvidia" to /dev/dri/card1
[ 25.699] loading driver: nvidia
[ 25.699] (==) Matched intel as autoconfigured driver 0
[ 25.699] (==) Matched nvidia as autoconfigured driver 1
[ 25.699] (==) Matched nouveau as autoconfigured driver 2
[ 25.699] (==) Matched nv as autoconfigured driver 3
[ 25.699] (==) Matched modesetting as autoconfigured driver 4
[ 25.699] (==) Matched fbdev as autoconfigured driver 5
[ 25.699] (==) Matched vesa as autoconfigured driver 6
[ 25.699] (==) Assigned the driver to the xf86ConfigLayout
[ 25.699] (II) LoadModule: "intel"
[ 25.700] (II) Loading /usr/lib64/xorg/modules/drivers/intel_drv.so
[ 25.701] (II) Module intel: vendor="X.Org Foundation"
[ 25.701] compiled for 1.20.8, module version = 2.99.917
[ 25.701] Module class: X.Org Video Driver
[ 25.701] ABI class: X.Org Video Driver, version 24.1
[ 25.701] (II) LoadModule: "nvidia"
[ 25.701] (II) Loading /usr/lib64/xorg/modules/drivers/nvidia_drv.so
[ 25.705] (II) Module nvidia: vendor="NVIDIA Corporation"
[ 25.705] compiled for 1.6.99.901, module version = 1.0.0
[ 25.705] Module class: X.Org Video Driver
[ 25.706] (II) LoadModule: "nouveau"
[ 25.706] (WW) Warning, couldn't open module nouveau
[ 25.706] (EE) Failed to load module "nouveau" (module does not exist, 0)
[ 25.706] (II) LoadModule: "nv"
[ 25.706] (WW) Warning, couldn't open module nv
[ 25.706] (EE) Failed to load module "nv" (module does not exist, 0)
[ 25.706] (II) LoadModule: "modesetting"
[ 25.706] (II) Loading /usr/lib64/xorg/modules/drivers/modesetting_drv.so
[ 25.707] (II) Module modesetting: vendor="X.Org Foundation"
[ 25.707] compiled for 1.20.8, module version = 1.20.8
[ 25.707] Module class: X.Org Video Driver
[ 25.707] ABI class: X.Org Video Driver, version 24.1
[ 25.707] (II) LoadModule: "fbdev"
[ 25.707] (WW) Warning, couldn't open module fbdev
[ 25.707] (EE) Failed to load module "fbdev" (module does not exist, 0)
[ 25.707] (II) LoadModule: "vesa"
[ 25.707] (WW) Warning, couldn't open module vesa
[ 25.707] (EE) Failed to load module "vesa" (module does not exist, 0)
[ 25.707] (II) intel: Driver for Intel(R) Integrated Graphics Chipsets:
i810, i810-dc100, i810e, i815, i830M, 845G, 854, 852GM/855GM, 865G,
915G, E7221 (i915), 915GM, 945G, 945GM, 945GME, Pineview GM,
Pineview G, 965G, G35, 965Q, 946GZ, 965GM, 965GME/GLE, G33, Q35, Q33,
GM45, 4 Series, G45/G43, Q45/Q43, G41, B43
[ 25.707] (II) intel: Driver for Intel(R) HD Graphics
[ 25.707] (II) intel: Driver for Intel(R) Iris(TM) Graphics
[ 25.707] (II) intel: Driver for Intel(R) Iris(TM) Pro Graphics
[ 25.707] (II) NVIDIA dlloader X Driver 440.82 Wed Apr 1 19:50:17 UTC 2020
[ 25.707] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs
[ 25.707] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
[ 25.716] (II) intel(0): Using Kernel Mode Setting driver: i915, version 1.6.0 20200313
[ 25.729] (WW) Falling back to old probe method for modesetting
[ 25.729] (II) Loading sub module "fb"
[ 25.729] (II) LoadModule: "fb"
[ 25.730] (II) Loading /usr/lib64/xorg/modules/libfb.so
[ 25.730] (II) Module fb: vendor="X.Org Foundation"
[ 25.730] compiled for 1.20.8, module version = 1.0.0
[ 25.730] ABI class: X.Org ANSI C Emulation, version 0.4
[ 25.730] (II) Loading sub module "wfb"
[ 25.730] (II) LoadModule: "wfb"
[ 25.730] (II) Loading /usr/lib64/xorg/modules/libwfb.so
[ 25.731] (II) Module wfb: vendor="X.Org Foundation"
[ 25.731] compiled for 1.20.8, module version = 1.0.0
[ 25.731] ABI class: X.Org ANSI C Emulation, version 0.4
[ 25.731] (II) Loading sub module "ramdac"
[ 25.731] (II) LoadModule: "ramdac"
[ 25.731] (II) Module "ramdac" already built-in
[ 25.733] (--) intel(0): Integrated Graphics Chipset: Intel(R) HD Graphics
[ 25.733] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1, sse4.2, avx, avx2; using a maximum of 6 threads
[ 25.733] (II) intel(0): Creating default Display subsection in Screen section
"Default Screen Section" for depth/fbbpp 24/32
[ 25.733] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[ 25.733] (==) intel(0): RGB weight 888
[ 25.733] (==) intel(0): Default visual is TrueColor
[ 25.733] (II) intel(0): Output eDP1 has no monitor section
[ 25.733] (**) intel(0): Found backlight control interface intel_backlight (type 'raw') for output eDP1
[ 25.733] (II) intel(0): Enabled output eDP1
[ 25.733] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[ 25.733] (II) intel(0): Output VIRTUAL1 has no monitor section
[ 25.733] (II) intel(0): Enabled output VIRTUAL1
[ 25.733] (--) intel(0): Output eDP1 using initial mode 1920x1080 on pipe 0
[ 25.733] (==) intel(0): TearFree enabled
[ 25.733] (==) intel(0): Using gamma correction (1.0, 1.0, 1.0)
[ 25.733] (==) intel(0): DPI set to (96, 96)
[ 25.733] (II) Loading sub module "dri3"
[ 25.733] (II) LoadModule: "dri3"
[ 25.733] (II) Module "dri3" already built-in
[ 25.733] (II) Loading sub module "dri2"
[ 25.733] (II) LoadModule: "dri2"
[ 25.733] (II) Module "dri2" already built-in
[ 25.733] (II) Loading sub module "present"
[ 25.733] (II) LoadModule: "present"
[ 25.733] (II) Module "present" already built-in
[ 25.733] (==) NVIDIA(G0): Depth 24, (==) framebuffer bpp 32
[ 25.733] (==) NVIDIA(G0): RGB weight 888
[ 25.733] (==) NVIDIA(G0): Default visual is TrueColor
[ 25.733] (==) NVIDIA(G0): Using gamma correction (1.0, 1.0, 1.0)
[ 25.734] (**) Option "AllowNVIDIAGpuScreens"
[ 25.734] (**) NVIDIA(G0): Enabling 2D acceleration
[ 25.734] (II) Loading sub module "glxserver_nvidia"
[ 25.734] (II) LoadModule: "glxserver_nvidia"
[ 25.734] (II) Loading /usr/lib64/xorg/modules/extensions/libglxserver_nvidia.so
[ 25.768] (II) Module glxserver_nvidia: vendor="NVIDIA Corporation"
[ 25.768] compiled for 1.6.99.901, module version = 1.0.0
[ 25.768] Module class: X.Org Server Extension
[ 25.768] (II) NVIDIA GLX Module 440.82 Wed Apr 1 19:47:36 UTC 2020
[ 25.770] (II) NVIDIA: The X server supports PRIME Render Offload.
[ 26.259] (--) NVIDIA(0): Valid display device(s) on GPU-0 at PCI:1:0:0
[ 26.259] (--) NVIDIA(0): DFP-0
[ 26.259] (--) NVIDIA(0): DFP-1 (boot)
[ 26.259] (--) NVIDIA(0): DFP-2
[ 26.259] (II) NVIDIA(G0): NVIDIA GPU GeForce GTX 1660 Ti (TU116-A) at PCI:1:0:0 (GPU-0)
[ 26.260] (--) NVIDIA(G0): Memory: 6291456 kBytes
[ 26.260] (--) NVIDIA(G0): VideoBIOS: 90.16.2c.00.0d
[ 26.260] (II) NVIDIA(G0): Detected PCI Express Link width: 16X
[ 26.260] (--) NVIDIA(GPU-0): DFP-0: disconnected
[ 26.260] (--) NVIDIA(GPU-0): DFP-0: Internal TMDS
[ 26.260] (--) NVIDIA(GPU-0): DFP-0: 165.0 MHz maximum pixel clock
[ 26.260] (--) NVIDIA(GPU-0):
[ 26.260] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): connected
[ 26.260] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): Internal DisplayPort
[ 26.260] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): 2660.0 MHz maximum pixel clock
[ 26.260] (--) NVIDIA(GPU-0):
[ 26.261] (--) NVIDIA(GPU-0): DFP-2: disconnected
[ 26.261] (--) NVIDIA(GPU-0): DFP-2: Internal TMDS
[ 26.261] (--) NVIDIA(GPU-0): DFP-2: 165.0 MHz maximum pixel clock
[ 26.261] (--) NVIDIA(GPU-0):
[ 26.261] (II) NVIDIA(G0): Validated MetaModes:
[ 26.261] (II) NVIDIA(G0): "NULL"
[ 26.261] (**) NVIDIA(G0): Virtual screen size configured to be 1920 x 1080
[ 26.261] (WW) NVIDIA(G0): Unable to get display device for DPI computation.
[ 26.261] (==) NVIDIA(G0): DPI set to (75, 75); computed from built-in default
[ 26.261] (II) UnloadModule: "modesetting"
[ 26.261] (II) Unloading modesetting
[ 26.266] (II) intel(0): SNA initialized with Coffeelake (gen9) backend
[ 26.266] (==) intel(0): Backing store enabled
[ 26.266] (==) intel(0): Silken mouse enabled
[ 26.266] (II) intel(0): HW Cursor enabled
[ 26.267] (==) intel(0): DPMS enabled
[ 26.267] (==) intel(0): Display hotplug detection enabled
[ 26.267] (II) intel(0): [DRI2] Setup complete
[ 26.267] (II) intel(0): [DRI2] DRI driver: i965
[ 26.267] (II) intel(0): [DRI2] VDPAU driver: va_gl
[ 26.267] (II) intel(0): direct rendering: DRI2 DRI3 enabled
[ 26.267] (II) intel(0): hardware support for Present enabled
[ 26.267] (II) NVIDIA: Using 24576.00 MB of virtual memory for indirect memory
[ 26.267] (II) NVIDIA: access.
[ 26.276] (II) NVIDIA(G0): ACPI: failed to connect to the ACPI event daemon; the daemon
[ 26.276] (II) NVIDIA(G0): may not be running or the "AcpidSocketPath" X
[ 26.276] (II) NVIDIA(G0): configuration option may not be set correctly. When the
[ 26.276] (II) NVIDIA(G0): ACPI event daemon is available, the NVIDIA X driver will
[ 26.276] (II) NVIDIA(G0): try to use it to receive ACPI event notifications. For
[ 26.276] (II) NVIDIA(G0): details, please see the "ConnectToAcpid" and
[ 26.276] (II) NVIDIA(G0): "AcpidSocketPath" X configuration options in Appendix B: X
[ 26.276] (II) NVIDIA(G0): Config Options in the README.
[ 26.329] (II) NVIDIA(G0): Setting mode "NULL"
[ 26.359] (==) NVIDIA(G0): Disabling shared memory pixmaps
[ 26.359] (==) NVIDIA(G0): Backing store enabled
[ 26.359] (==) NVIDIA(G0): Silken mouse enabled
[ 26.359] (==) NVIDIA(G0): DPMS enabled
[ 26.359] (II) Loading sub module "dri2"
[ 26.359] (II) LoadModule: "dri2"
[ 26.359] (II) Module "dri2" already built-in
[ 26.359] (II) NVIDIA(G0): [DRI2] Setup complete
[ 26.359] (II) NVIDIA(G0): [DRI2] VDPAU driver: nvidia
[ 26.359] (II) Initializing extension Generic Event Extension
[ 26.360] (II) Initializing extension SHAPE
[ 26.360] (II) Initializing extension MIT-SHM
[ 26.360] (II) Initializing extension XInputExtension
[ 26.360] (II) Initializing extension XTEST
[ 26.360] (II) Initializing extension BIG-REQUESTS
[ 26.360] (II) Initializing extension SYNC
[ 26.360] (II) Initializing extension XKEYBOARD
[ 26.360] (II) Initializing extension XC-MISC
[ 26.360] (II) Initializing extension SECURITY
[ 26.360] (II) Initializing extension XFIXES
[ 26.361] (II) Initializing extension RENDER
[ 26.361] (II) Initializing extension RANDR
[ 26.361] (II) Initializing extension COMPOSITE
[ 26.361] (II) Initializing extension DAMAGE
[ 26.361] (II) Initializing extension MIT-SCREEN-SAVER
[ 26.361] (II) Initializing extension DOUBLE-BUFFER
[ 26.361] (II) Initializing extension RECORD
[ 26.361] (II) Initializing extension DPMS
[ 26.361] (II) Initializing extension Present
[ 26.361] (II) Initializing extension DRI3
[ 26.361] (II) Initializing extension X-Resource
[ 26.361] (II) Initializing extension XVideo
[ 26.361] (II) Initializing extension XVideo-MotionCompensation
[ 26.361] (II) Initializing extension GLX
[ 26.361] (II) Initializing extension GLX
[ 26.361] (II) Indirect GLX disabled.
[ 26.383] (II) AIGLX: Loaded and initialized i965
[ 26.383] (II) GLX: Initialized DRI2 GL provider for screen 0
[ 26.383] (II) Initializing extension XFree86-VidModeExtension
[ 26.384] (II) Initializing extension XFree86-DGA
[ 26.384] (II) Initializing extension XFree86-DRI
[ 26.384] (II) Initializing extension DRI2
[ 26.384] (II) Initializing extension NV-GLX
[ 26.384] (II) Initializing extension NV-CONTROL
[ 26.386] (II) intel(0): switch to mode [email protected] on eDP1 using pipe 0, position (0, 0), rotation normal, reflection none
[ 26.388] (II) intel(0): Setting screen physical size to 508 x 285
[ 26.988] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): connected
[ 26.988] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): Internal DisplayPort
[ 26.988] (--) NVIDIA(GPU-0): WIT DISPLAY PORT (DFP-1): 2660.0 MHz maximum pixel clock
[ 26.988] (--) NVIDIA(GPU-0):
[ 26.988] (EE) Failed to open authorization file "/var/run/sddm/{248a5522-1b5e-4998-9e20-ae4671e50102}": No such file or directory
[ 28.268] (II) intel(0): EDID vendor "AUO", prod id 53485
[ 28.269] (II) intel(0): Using EDID range info for horizontal sync
[ 28.269] (II) intel(0): Using EDID range info for vertical refresh
[ 28.269] (II) intel(0): Printing DDC gathered Modelines:
[ 28.269] (II) intel(0): Modeline "1920x1080"x0.0 290.80 1920 2028 2076 2120 1080 1090 1100 1142 -hsync -vsync (137.2 kHz eP)
[ 28.269] (II) intel(0): Modeline "1920x1080"x0.0 116.40 1920 2028 2076 2120 1080 1090 1100 1142 -hsync -vsync (54.9 kHz e)
答案1
如果您摆脱 nouveau 以使用 nvidia 驱动程序：
https://www.if-not-true-then-false.com/2015/fedora-nvidia-guide/
您需要使用 __GLX_VENDOR_LIBRARY_NAME=nvidia 强制驱动程序：
$ inxi -G
Graphics: Device-1: Intel UHD Graphics 620 driver: i915 v: kernel
Device-2: NVIDIA GP106 [GeForce GTX 1060 3GB] driver: nvidia v: 470.74
Device-3: Acer SunplusIT Integrated Camera type: USB driver: uvcvideo
Display: wayland server: X.Org 1.21.1.2 driver: loaded: nvidia resolution: 1920x1080~60Hz
OpenGL: renderer: Mesa Intel UHD Graphics 620 (KBL GT2) v: 4.6 Mesa 21.1.8
$ DRI_PRIME=0 glxinfo | grep 'OpenGL renderer string'
OpenGL renderer string: Mesa Intel(R) UHD Graphics 620 (KBL GT2)
$ DRI_PRIME=1 glxinfo | grep 'OpenGL renderer string'
libGL error: failed to create dri screen
libGL error: failed to load driver: nouveau
OpenGL renderer string: llvmpipe (LLVM 12.0.1, 256 bits)
$ __GLX_VENDOR_LIBRARY_NAME=nvidia DRI_PRIME=1 glxinfo | grep 'OpenGL renderer string'
OpenGL renderer string: NVIDIA GeForce GTX 1060 3GB/PCIe/SSE2