[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

In a more pure development environment, I can confirm this bug without
needing hybrid GPUs, or gdm3.

Just the Nvidia driver and Xorg results in no outputs/monitors detected:

$ xrandr
Screen 0: minimum 8 x 8, current 640 x 480, maximum 16384 x 16384

To work around the problem I need to run Xorg as root. Then I get:

$ xrandr
Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 16384 x 16384
DVI-I-0 disconnected primary (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 
324mm
   1920x1200 59.95*+  59.88  
   1920x1080 60.0059.9450.0023.98  
   1600x1200 60.00  
   1280x1024 75.0260.02  
   1280x720  60.0059.9450.00  
   1152x864  75.00  
   1024x768  75.0360.00  
   800x600   75.0060.32  
   720x576   50.00  
   720x480   59.94  
   640x480   75.0059.9459.93  

So perhaps gdm3 is sometimes missing whatever /dev/* privileges it needs
to start Xorg on Nvidia properly. And perhaps lightdm just always does
it right.

Although a solution here in the medium term might lay in gdm3, I would
more like to see the Nvidia driver fix this bug. Because I can reproduce
it without any *dm. Just the kernel + Nvidia driver + Xorg.

** Changed in: gdm3 (Ubuntu)
   Status: Confirmed => Opinion

** Changed in: mutter (Ubuntu)
   Status: Confirmed => Invalid

** Also affects: nvidia-graphics-drivers-418 (Ubuntu)
   Importance: Undecided
   Status: New

** Changed in: nvidia-graphics-drivers-418 (Ubuntu)
   Status: New => Confirmed

** Also affects: nvidia-graphics-drivers-375 (Ubuntu)
   Importance: Undecided
   Status: New

** Changed in: nvidia-graphics-drivers-375 (Ubuntu)
   Status: New => Confirmed

** Summary changed:

- gdm3, hybrid nvidia with modeset=1, no external monitors detected
+ nvidia-drm.modeset=1 results in no monitors detected by Xorg

** Changed in: gdm3 (Ubuntu)
   Status: Opinion => Invalid

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

** Tags added: nvidia-drm.modeset

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

This works. Thanks. What does gdm3 do that requires this?

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Jeremy Soller]

The solution to this is to run X11 as root, so it can use VGA arbiter
and detect displays on both the NVIDIA and modesetting drivers.

Add this to /etc/X11/Xwrapper.config :
needs_root_rights = yes

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim]

I'm on Ubuntu 19.04 as well and having issues with this.

I have an i7-8750h paired with a gtx 1050ti in a Dell G515.

I don't exactly what I did, but I can give a general idea:

I decided this morning that battery life was important to me, so I
tinkered around with TLP. After I did that everything seemed fine, but
when I plugged an HDMI cord back into my laptop, after reenabling my
discrete GPU it no longer works. I have uninstalled and reinstalled TLP,
I have reinstalled gdm3, no dice, and I have tried reverting just about
everything I can think of that pertains to displays. I still can't get
it. Switching over to lightdm for now, this is very frustrating though.

Before I was working with TLP though, I was able to connect to external
displays via this HDMI cord no problem. I know it is not a hardware
issue because before I log in the external display shows the image I
have for my lockscreen. However, it's once I log in that the display
turns off. Hope this helps. I'd love to help get gdm3 working as well.
LMK if you need anything including logs.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

Still present in 19.04, although as a workaround, the nvidia drivers
have reverted to installing without modeset=1, so external monitors
work, and Optimus users get dreadful tearing on their laptop's internal
screen.

With modeset=1 (which in my case was a setting preserved during the update to 
19.04):
At the login prompt (using gdm3) external monitors are powered on and display a 
background graphic. 
During session start, they are lost. 

External monitors work with lightdm or sddm3, both supported display managers 
in Ubuntu, so this remains the workaround.
 So odd that Fedora doesn't care about this. It's a dreadful welcome to Linux 
moment. Using gdm3 as the default display manager seems insane given this bug.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Juan Cabello]

After adding the line "/usr/bin/xinit" to gdm3.service I get this in
every boot:

ProblemType: Crash
Architecture: amd64
Date: Mon Mar 25 19:17:11 2019
DistroRelease: Ubuntu 18.04
ExecutablePath: /usr/lib/xorg/Xorg
ExecutableTimestamp: 1543339632
ProcCmdline: /usr/lib/xorg/Xorg :0
...

Did you guys find out why? And, why does it take too long to show the
login screen?

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Ivan]

Forgot to add: Ubuntu 18.04.2

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Ivan]

I confirm the bug exists and workarounds work, both with lightdm and
ExecStartPre line. Also, adding xinit to ExecStartPre messes up suspend
functionality. That is a pity...

Laptop: Thinkpad P1 with nvidia graphics

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Re: [Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

Personally, I have not encountered that when using ubuntu or fedora and
simply swapping gdm3 for lightdm but it's good that the other bug report
has a fix. It looks like a hidpi bug; none of my monitors are hidpi.

On Thu, 21 Feb 2019 at 12:50, Stefano <1716...@bugs.launchpad.net>
wrote:

> The problem with the lightdm workaround is that many had this cursor
> issue:
>
> https://bugs.launchpad.net/ubuntu/+source/xfce4-settings/+bug/1770948
>
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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Stefano]

The problem with the lightdm workaround is that many had this cursor
issue:

https://bugs.launchpad.net/ubuntu/+source/xfce4-settings/+bug/1770948

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Stefano]

Yes I was talking about the gdm3 workaround

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Re: [Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

There are two workarounds mentioned: swap to lightdm and manipulate gdm3
start. I think you refer to the gdm3 startup changes when you say it causes
problems with suspend/resume (which I didn't try).
The other workaround is changing display manager to lightdm (or sddm, the
KDE display manager).
swapping to lightdm has not caused any suspend/resume problems for me on
the two Optimus laptops I used,  so I think the lightdm workaround is ok.
It was the default display manager of ubuntu for a long time and is still
the default for xubuntu.


On Thu, 21 Feb 2019 at 08:45, Stefano <1716...@bugs.launchpad.net> wrote:

> Yes but this workaround is going to create others issue for suspend and
> resume.
>
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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Stefano]

Yes but this workaround is going to create others issue for suspend and
resume.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[losingYou]

Running Ubuntu 18.10 here. Wanted to do a presentation with my Notebook, but it 
failed me cause of this bug.
I can confirm that it works "Out of the box" with lightdm and that it also 
works with gdm3 if you modify /lib/systemd/system/gdm3.service, changing the 
"ExecStartPre" line to the above mentioned: ExecStartPre=/usr/bin/xinit 
/usr/share/gdm/generate-config

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Jefferson H. Xavier]

Same issue in here on Ubuntu 18.04.1 LTS. I have a Dell G3 3579 with Nvidia 
Geforce 1050TI. I've tried to use a Samsung SmartTV as a secondary display 
connected to HDMI port but Gnome settings only shows laptop display. I've 
tested drivers 390, 396, 410, and 415 without success. This issue doesn't 
occurs using lightdm instead of gdm3.
I think developers have to solve this issue that has been reporting since 
2017-09-13 and people who wants do use a external HDMI TV/Monitor to play 
games, like me, will face this issue.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

sddm works too: I just put kde plasma on my ThinkPad P50 with ubuntu
18.10, it works well.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Stefano]

18.10 Lightdm works but GDM works only with the mentioned
hack/workaround (but with slowdowns):

ExecStartPre=/usr/bin/xinit /usr/share/gdm/generate-config

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

** Tags removed: artful

** Tags added: cosmic

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

** Also affects: mutter (Ubuntu)
   Importance: Undecided
   Status: New

** Changed in: mutter (Ubuntu)
   Status: New => Confirmed

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

The current 18.10 nvidia packages have this problem too. That is, out of
the box, the nvidia driver defaults to KMS now (first time on any
distro) but the nvidia driver does not detect external screens. Probably
should be a new bug I guess.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

** Tags added: artful bionic

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

I re-confirm this. Stock 18.04 has no graphics in pure nvidia mode (on a
Thinkpad W520 in discrete graphics).

lightdm works.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Aurélien PIERRE]

Same on Thinkpad P51 (Nvidia Quadro M2200), Ubuntu 18.04, Nvidia 390

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Launchpad Bug Tracker]

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

** Changed in: gdm3 (Ubuntu)
   Status: New => Confirmed

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

However with this change I'm seeing very long pauses on
restart/shutdown, i haven't found any iclue why in the logs.

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Hon Weng Chong]

Daniel, yes that one line fixes the bug. It's not a proper fix but a
work-around for GDM3.

There's something about gdm-xsession being run that's different from
LightDM that's not triggering the nvidia modeset drivers to turn detect
external monitors and enabling PRIME sync. I discovered the workaround
after accidentally doing a sudo startx and noticing that both PRIME sync
and my external monitor had been enabled.

As this is quite an innocuous fix, would it be possible to upstream this
into the Ubuntu GDM3 codebase until the GDM3 maintainers decide that it
would be worth their time to actually look at this bug seriously and fix
it in their codebase? Otherwise it gets annoying having to patch the
systemd service everytime GDM3 gets a point update.

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Re: [Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

Let me clarify: the problem exists in Fedora too. Until a few hours ago, I
had never got prime sync and gdm3 working in any distribution.
This one line fix works, believe it or not. It's really a half a line fix.
I have only tried it in ubuntu 17.10 so far. Fedora is not a focus for me,
and I have other problems with nvidia binary support on Fedora 27. The
learning curve for Fedora is steep for me so I am not motivated to
investigate it.


On 13 December 2017 at 17:50, Daniel van Vugt  wrote:

> Actually the offending line is directly from Debian:
> http://http.debian.net/debian/pool/main/g/gdm3/gdm3_3.26.2.
> 1-2.debian.tar.xz
>
> ** Also affects: gdm3 (Debian)
>Importance: Undecided
>Status: New
>
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  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

Tim, are you really saying just that one-line change fixed it?...

I can confirm at least that /usr/share/gdm/generate-config is introduced
only by Debian/Ubuntu packaging. It's not part of the upstream GDM
project. So if Fedora's approach of running under xinit works then we
should probably do the same. I can't yet see why it works though.

** Package changed: gnome-shell (Ubuntu) => gdm3 (Ubuntu)

** Tags added: multimonitor

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Title:
  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

Actually the offending line is directly from Debian:
http://http.debian.net/debian/pool/main/g/gdm3/gdm3_3.26.2.1-2.debian.tar.xz

** Also affects: gdm3 (Debian)
   Importance: Undecided
   Status: New

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Title:
  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

Celebratory fireworks from me.


It seems to work. For ubuntu the only difference is 

[Service]
ExecStartPre=/usr/share/gdm/generate-config

becomes


[Service]
ExecStartPre=/usr/bin/xinit /usr/share/gdm/generate-config

I have a proper ubuntu gnome session running with gdm, an external
monitor and laptop panel, with prime sync on and no flickering, running
'ubuntu on xorg'

*** FOR THE FIRST TIME EVER ***

on my thinkpad W520 which is old but is a genuine Optimus laptop with Quadro 
graphics on the nvidia 387.34 binary driver
in Optimus mode.

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  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Tim Richardson]

ubuntu user Hon Weng Chong has emailed me as he continues to investigate the 
problem.
He believes he has proof that it is is GDM configuration issue and has provided 
the following fix


Hey Tim,

I figured out a hack solution to the GDM prime issue. If you replace
/lib/systemd/system/gdm3.service with this file:

https://gist.github.com/hwchong/b3634b387e91b38d355a0500ffecfc7d

and /etc/X11/xorg.conf with this:

https://gist.github.com/hwchong/28d7c70aafd62a0d3114c5746da7da36

You should be able to use Prime Sync with your Intel graphics card and
have an external monitor connected to the Nvidia GPU without using
LightDM.

Cheers,
Hon


His proposed changes to xorg are probably not significant. He is proposing to 
add this to nvidia options, but this can be done via the GUI or command line.

Option "metamodes" "nvidia-auto-select +0+0
{ForceCompositionPipeline=On, ForceFullCompositionPipeline=On}"



The revised /lib/systemd/system/gdm3.service he proposes is
is
--> Compared to Fedora 27's config, changes seem to be the addition of 
ExecStartPre=/usr/bin/xinit /usr/share/gdm/generate-config
.
.
.
RestartSec=1s
ExecReload=/usr/share/gdm/generate-config


[Unit]
Description=GNOME Display Manager

# replaces the getty
Conflicts=getty@tty1.service
After=getty@tty1.service

# replaces plymouth-quit since it quits plymouth on its own
Conflicts=plymouth-quit.service
After=plymouth-quit.service

# Needs all the dependencies of the services it's replacing
# pulled from getty@.service and plymouth-quit.service
# (except for plymouth-quit-wait.service since it waits until
# plymouth is quit, which we do)
After=rc-local.service plymouth-start.service systemd-user-sessions.service

# GDM takes responsibility for stopping plymouth, so if it fails
# for any reason, make sure plymouth still stops
OnFailure=plymouth-quit.service

[Service]
ExecStartPre=/usr/bin/xinit /usr/share/gdm/generate-config
ExecStart=/usr/sbin/gdm3
KillMode=mixed
Restart=always
RestartSec=1s
IgnoreSIGPIPE=no
BusName=org.gnome.DisplayManager
StandardOutput=syslog
StandardError=inherit
EnvironmentFile=-/etc/default/locale
ExecReload=/usr/share/gdm/generate-config
ExecReload=/bin/kill -SIGHUP $MAINPID

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  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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[Bug 1716857] Re: gdm3, hybrid nvidia with modeset=1, no external monitors detected

[Daniel van Vugt]

** Tags added: nvidia

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  gdm3, hybrid nvidia with modeset=1, no external monitors detected

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