"nvidia on-demand" mode does not support external displays

[Matt W.]

In a recent driver, Nvidia finally added Linux support for render offload, where most graphics are rendered on the CPU-onboard GPU and only certain applications are rendered on the discrete Nvidia GPU. I know that Ubuntu 19.10 started shipping some updated Xorg packages to support this. For the most part the mode seems to work great.

On my laptop, however, I have found that the "on demand" mode does not detect external monitors (and the monitor says it is not receiving a signal). Switching to "Nvidia" mode, where everything is rendered on the discrete GPU, makes the external displays work. The laptop is a Lenovo Thinkpad X1 Extreme (Gen 1). I have found this occurs both with nvidia-graphics-drivers-435 and nvidia-graphics-drivers-440 in the "graphics-drivers" ppa.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: nvidia-driver-435 435.21-0ubuntu2
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Uname: Linux 5.3.0-19-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Oct 21 13:17:38 2019
InstallationDate: Installed on 2019-09-04 (47 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: nvidia-graphics-drivers-435
UpgradeStatus: Upgraded to eoan on 2019-10-21 (0 days ago)
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
DistroRelease: Ubuntu 19.10
InstallationDate: Installed on 2019-09-04 (47 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
NonfreeKernelModules: nvidia_modeset nvidia
Package: nvidia-driver-435 435.21-0ubuntu2
PackageArchitecture: amd64
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Tags: eoan third-party-packages
Uname: Linux 5.3.0-19-generic x86_64
UpgradeStatus: Upgraded to eoan on 2019-10-21 (0 days ago)
UserGroups:

_MarkForUpload: True

[Matt W. (mw1234)]

apport information

[Matt W. (mw1234)]

apport information

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Matt W. (mw1234)]

After some more research I found out that this is actually due to an unimpelmented feature in Nvidia's drivers.

On this model of laptop, the video output ports all connect directly to the discrete Nvidia GPU, and Nvidia's drivers do not yet support the GPU being used as a sink from the integrated GPU and piping the integrated GPU's output to a display.

[bram lagerweij (bramlagerweij16)]

Just for future reference on the Nvidia Forum, this problem is mentioned in:
https://forums.developer.nvidia.com/t/support-external-displays-in-render-offload-mode/107046/7

This make the whole On-Demand option impossible to use for me, and I was seeing forward to it so much.

[ELMX (elx-1)]

/etc/default/grub

>> i915.force_probe=pci:v00008086d00004C9Asv*sd*bc03sc*i* (this is my i915 driver module alias)
but, you can get PCI Device ID, with lspci -nnk command
>> i915.force_probe=PCI_Device_ID (no BusID)

update-grub

/etc/environment
>> export LIBGL_DRI2_DISABLE=true
>> export LIBGL_DRI3_DISABLE=true

reboot system

ps
My bios set mshybrid (optimus) and system is nvidia prime on-demand (offloading)
Intel iGPU and nvidia dGPU
Working external monitor, HDMI and typec (displayport)

[ELMX (elx-1)]

Intel iGPU and nvidia dGPU on dell g7 7588
intel (igpu) connected do integrated monitor and a external typec output, and dGPU (nvidia) with an external gpu

My system is
Linux 7588 5.13.0-39-generic #44~20.04.1-Ubuntu SMP Thu Mar 24 16:43:35 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
nvidia, 510.54, 5.13.0-39-generic, x86_64: installed

Appears that new nvidia new updates supports better dual output heads on like (intel handling one external output and nvidia another external port )

Remember that it is on nvidia-prime on-demand profile

for me no need anymore: i915.force_probe=PCI_Device_ID (no BusID)

Thank you