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[SOLVED] Rainbow flash glitch with LightDM + XFCE

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MiracleDinner
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Re: Rainbow flash glitch with LightDM + XFCE

#21 Post by MiracleDinner »

Okay, so I run

Code: Select all

sudo apt purge *gnome* *gdm*
?

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Re: Rainbow flash glitch with LightDM + XFCE

#22 Post by Aki »

Hello,
This is the command that will list the packages that are in state "removed", but that have still configuration files left in the system:

Code: Select all

dpkg-query -l | grep ^rc | tr -s ' ' | cut -d ' '  -f 2
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Re: Rainbow flash glitch with LightDM + XFCE

#23 Post by MiracleDinner »

Forgive me for taking so long to get around to this, but I purged all the packages listed from that command and I'm still experiencing the rainbow flash glitch for every login with lightdm-gtk-greeter, and occasionally for slick-greeter usually when switching between users.

Here is my system log after running the purge for all of those, on a fresh boot in which I did experience the glitch:

https://pastebin.com/NnNy09Fx

As the exact same glitch happens regardless of what kernel version I use, I'm now just sticking to the Stable 5.10.0 kernel (which the above log is running on). I think I did attempt to install firmware-misc-nonfree from backports but it still did not do anything.

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Re: Rainbow flash glitch with LightDM + XFCE

#24 Post by Aki »

Hello,
Just a guess: try to disable temporarily (or uninstall, if not required) the xdg-desktop-portal service (it's automatically launched after the start of the session):

Code: Select all

[..]
Dec 30 15:09:10 elimina-debian-crystal dbus-daemon[4189]: [session uid=1000 pid=4189] Activating via systemd: service name='org.freedesktop.portal.Desktop' unit='xdg-desktop-portal.service' requested by ':1.29' (uid=1000 pid=4353 comm="/usr/libexec/ibus-extension-gtk3 ")
Dec 30 15:09:10 elimina-debian-crystal systemd[4167]: Starting Portal service...
Dec 30 15:09:10 elimina-debian-crystal dbus-daemon[4189]: [session uid=1000 pid=4189] Successfully activated service 'org.xfce.Xfconf'
Dec 30 15:09:10 elimina-debian-crystal at-spi-bus-launcher[4388]: dbus-daemon[4388]: Successfully activated service 'org.a11y.atspi.Registry'
Dec 30 15:09:10 elimina-debian-crystal at-spi-bus-launcher[4402]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Dec 30 15:09:10 elimina-debian-crystal systemd[4167]: Started Tracker metadata extractor.
Dec 30 15:09:10 elimina-debian-crystal dbus-daemon[4189]: [session uid=1000 pid=4189] Activating via systemd: service name='org.freedesktop.portal.Documents' unit='xdg-document-portal.service' requested by ':1.34' (uid=1000 pid=4404 comm="/usr/libexec/xdg-desktop-portal ")
Dec 30 15:09:10 elimina-debian-crystal systemd[4167]: Starting flatpak document portal service...
Dec 30 15:09:10 elimina-debian-crystal dbus-daemon[4189]: [session uid=1000 pid=4189] Activating via systemd: service name='org.freedesktop.impl.portal.PermissionStore' unit='xdg-permission-store.service' requested by ':1.35' (uid=1000 pid=4415 comm="/usr/libexec/xdg-document-portal ")
[..]
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Re: Rainbow flash glitch with LightDM + XFCE

#25 Post by MiracleDinner »

Okay so this morning I reinstalled Debian and I can confirm that, on an entirely fresh installation using the Calamares installer live nonfree xfce 11.6 iso, the glitch does occur.

@Aki I didn't see your post until after I did this reinstall, but running this tells me it's not on this new install?

Code: Select all

miracledinner@miracledinner-standard:~$ sudo systemctl status xdg-desktop-portal.service
[sudo] password for miracledinner: 
Unit xdg-desktop-portal.service could not be found.

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Re: Rainbow flash glitch with LightDM + XFCE

#26 Post by Aki »

Hello,
MiracleDinner wrote: 2023-01-01 18:01 Okay so this morning I reinstalled Debian and I can confirm that, on an entirely fresh installation using the Calamares installer live nonfree xfce 11.6 iso, the glitch does occur.
Happy you solved it.
MiracleDinner wrote: 2023-01-01 18:01 @Aki I didn't see your post until after I did this reinstall, but running this tells me it's not on this new install?

Code: Select all

miracledinner@miracledinner-standard:~$ sudo systemctl status xdg-desktop-portal.service
[sudo] password for miracledinner: 
Unit xdg-desktop-portal.service could not be found.
Yes, it looks like it's not installed now.
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Re: Rainbow flash glitch with LightDM + XFCE

#27 Post by MiracleDinner »

Aki wrote: 2023-01-01 22:39 Hello,
MiracleDinner wrote: 2023-01-01 18:01 Okay so this morning I reinstalled Debian and I can confirm that, on an entirely fresh installation using the Calamares installer live nonfree xfce 11.6 iso, the glitch does occur.
Happy you solved it.
MiracleDinner wrote: 2023-01-01 18:01 @Aki I didn't see your post until after I did this reinstall, but running this tells me it's not on this new install?

Code: Select all

miracledinner@miracledinner-standard:~$ sudo systemctl status xdg-desktop-portal.service
[sudo] password for miracledinner: 
Unit xdg-desktop-portal.service could not be found.
Yes, it looks like it's not installed now.
I did not say the glitch was solved. It's not solved - I still experience it exactly as before, the lightdm-gtk-greeter almost always has it and slick-greeter ocasionally has it. My post was to say that the glitch happens even on an entirely untouched new installation meaning it's not the case I misconfigured something or left some artefact behind that's causing it.

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Re: Rainbow flash glitch with LightDM + XFCE

#28 Post by Aki »

Hello,
MiracleDinner wrote: 2023-01-02 10:09 I did not say the glitch was solved. It's not solved - I still experience it exactly as before, the lightdm-gtk-greeter almost always has it and slick-greeter ocasionally has it. My post was to say that the glitch happens even on an entirely untouched new installation meaning it's not the case I misconfigured something or left some artefact behind that's causing it.
Sorry for the misunderstanding.

Does the glitch appear if you use Debian from a standard live xfce ISO image (for example [1]) ?

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[1] https://cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/debian-live-11.6.0-amd64-xfce.iso
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Re: Rainbow flash glitch with LightDM + XFCE

#29 Post by None1975 »

Sorry for my bad English. I used to use xfce4 too. And I have also noticed this glitch. This also happens with lxqt. After reading the forums, I realized that the culprit is xfwm4 (standard window manager for xfce4). Of course, you can use another window manager - openbox. I had done so. Using this manager (openbox) the problem disappeared.
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Re: Rainbow flash glitch with LightDM + XFCE

#30 Post by MiracleDinner »

@Aki As far as I can tell, no it doesn't, but that should be pretty obvious since the glitch seems to be tied to the specific combo of using lightdm to log into xfce, and the live iso doesn't have a lightdm login at all as far as I can tell, I go straight from grub to the plymouth logo to the xfce live desktop.

@None1975 Thank you very much for sharing your experience. To test your theory I installed compiz and set it as the default window manger by modifying ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-session.xml

I can confirm that indeed, I don't experience the glitch under compiz even with lightdm-gtk-greeter.

However, I'm not sure I want to stick with this solution as I'd been fairly comfortable with xfwm4 and I'm currently having a bit of a problem with compiz in that I found the default window titlebar theme hideous so I managed to change it to Mint-Y (I adore and use the Mint-Y themes and icons for XFCE) but I'm now missing minimise and maximise buttons! I also have a lot to learn about how to configure it and there are a few things that annoy me but I won't go into detail here. Perhaps that might be for another topic. But it would be good to know exactly why xfwm4 does this and if there's any way to fix it.

[Edit: I've quickly tried openbox and it also fixes the glitch but I'm also not entirely happy with changing to it so I'd still like a fix for xfwm]

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Re: Rainbow flash glitch with LightDM + XFCE

#31 Post by None1975 »

I'm also not entirely happy with changing to it so I'd still like a fix for xfwm
Maybe it will be fixed in 4.18.
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Re: Rainbow flash glitch with LightDM + XFCE

#32 Post by MiracleDinner »

None1975 wrote: 2023-01-03 13:41
I'm also not entirely happy with changing to it so I'd still like a fix for xfwm
Maybe it will be fixed in 4.18.
Speaking of which, and I apologise for not bringing this up earlier, but I did try installing sid (or more specifically what I did was used Calamares from the live nonfree xfce iso for Debian 11.6 and upgraded to sid from there) and I experienced the following glitch:

https://mega.nz/file/yGICBQoQ#DDsGT3S5G ... pnjYGCJJpc

So it seems as if one of more newer packages (I don't yet know which but based on your anecdote and my testing it would seem as if xfwm4 is at least one of those packages) does mean that there is no "rainbow flash" but there does seem to be a black flicker with similar timing that I don't particularly desire either. But I'm not keen on switching to testing or sid just to remove the rainbow flash and while I could recompile it per SimpleBackportCreation my experience is that this isn't always smooth and I'm not sure I would'nt have issues especially if doing so effectively meant I'd have to recompile and backport my entire desktop environment (which I'm not sure would be the case.)

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Re: Rainbow flash glitch with LightDM + XFCE

#33 Post by MiracleDinner »

Okay so I had a go at following SimpleBackportCreation for xfwm4 and to my suprise.... it was completely smooth, and didn't require me to upgrade anything else. Perhaps that is one interesting benefit of XFCE's modular design.

I'm now running XFCE 4.16 with XFWM 4.18 and I experience the black flicker sans rainbow flash exactly as in the video attached to my previous post.

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Re: Rainbow flash glitch with LightDM + XFCE

#34 Post by None1975 »

MiracleDinner wrote: 2023-01-03 16:42 I'm now running XFCE 4.16 with XFWM 4.18 and I experience the black flicker sans rainbow flash exactly as in the video attached to my previous post.
Sad to hear that. I think there are two ways out in this case. The first is to accept it and use it, and the second is to use another window manager.
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Re: Rainbow flash glitch with LightDM + XFCE

#35 Post by Aki »

Hello,
MiracleDinner wrote: 2022-12-19 09:43 If your hypothesis is that it's caused by the NVIDIA hybrid graphics, is there any way that I could verify this? E.g. might it be possible to entirely disable the NVIDIA GPU and see if the glitch still happens? I do note that I believe this glitch occurs regardless of whether I use the proprietary drivers or the nouveau drivers.
You can use the module_blacklist kernel option [1] to disable temporarily (at boot time) the loading of nvidia kernel modules (drivers):

Code: Select all

module_blacklist=  
Do not load a comma-separated list of modules.  Useful for debugging problem modules.
Even if I'm quite sure you are aware of this, you can check nvidia kernel modules names using the lsmod command.

HTH

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Re: Rainbow flash glitch with LightDM + XFCE

#36 Post by None1975 »

Aki wrote: 2023-01-05 09:27 You can use the module_blacklist kernel option [1] to disable temporarily (at boot time) the loading of nvidia kernel modules (drivers)
Hello. This is not fault of nvidia drivers. This is problem in xfwm4....
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Re: Rainbow flash glitch with LightDM + XFCE

#37 Post by Aki »

Hello,
None1975 wrote: 2023-01-05 12:47
Aki wrote: 2023-01-05 09:27 You can use the module_blacklist kernel option [1] to disable temporarily (at boot time) the loading of nvidia kernel modules (drivers)
Hello. This is not fault of nvidia drivers. This is problem in xfwm4....
@None1975
Thanks for your note. So far, I wasn't able to replicate the issue with the current Debian Stable (11.6) in a KVM installation (using lightdm and xfwm4 [1]).

I tested it with a graphic card different from the OP's ones (the graphic hardware of the OP is not available to me).

This let me suppose that xfwm4 could not be the cause, at least not only by itself. A hardware or software or mixed hardware/software cause could be involved. That's why I think it might be worth a try to exclude the nvidia proprietary kernel module as a contributing factor to the issue.

Anyway, it would interesting to take a look at the the changelog or the patch in version 4.18 of xfwm4 source code for the fix you were referring to in the previous post [2].

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[1] https://packages.debian.org/bullseye/xfwm4
[2] viewtopic.php?p=765158#p765158
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Re: Rainbow flash glitch with LightDM + XFCE

#38 Post by None1975 »

Aki wrote: 2023-01-05 13:16
Thanks for your note. So far, I wasn't able to replicate the issue with the current Debian Stable (11.6) in a KVM installation (using lightdm and xfwm4 [1]).

I tested it with a graphic card different from the OP's ones (the graphic hardware of the OP is not available to me).
Hello. What video card are you using?
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Re: Rainbow flash glitch with LightDM + XFCE

#39 Post by Aki »

Hello,
None1975 wrote: 2023-01-06 12:23
Aki wrote: 2023-01-05 13:16 [..] So far, I wasn't able to replicate the issue with the current Debian Stable (11.6) in a KVM installation (using lightdm and xfwm4 [1]).[..]
Hello. What video card are you using?
@None1975:
I tested Debian Stable 11.6 (lightdm + xfwm4) in two different virtual environments:

Code: Select all

--> virt-manager (Version: 1:3.2.0-3) + qemu-system-x86 (versione 1:5.2+dfsg-11+deb11u2); the graphic card is:
$ inxi -G
Graphics:
  Device-1: Red Hat QXL paravirtual graphic card driver: qxl v: kernel 
  Display: x11 server: X.Org 1.20.11 driver: loaded: qxl 
  note: n/a (using device driver) unloaded: fbdev,modesetting,vesa 
  resolution: 1024x768~60Hz 
  OpenGL: renderer: llvmpipe (LLVM 11.0.1 128 bits) v: 4.5 Mesa 20.3.5 

--> virtualbox-6.1 (Version: 6.1.40-154048~Debian~bullseye); the graphic card is:
VGA Compatible Controller: VMware SVGA II Adapter (prog-if 00 (VGA controller)]
There's *no glitch* whatsoever testing LightDM + XFCE with these VMs. They use emulated graphic cards, of course. The host for both VMs runs on a Nvidia GeForce 9600M GT.

After your previous post, I tested Debian Stable 11.6 (lightdm + xfwm4) on bare metal, too.

The results are different with bare metal:
a) the first computer tested is equipped with a Nvidia graphic card:

Code: Select all

$ inxi -G
Graphics:  Device-1: NVIDIA G96CM [GeForce 9600M GT] driver: nouveau v: kernel 
           Display: x11 server: X.Org 1.20.11 driver: loaded: modesetting unloaded: fbdev,vesa resolution: 1280x800~60Hz 
[..]
           OpenGL: renderer: NV96 v: 3.3 Mesa 20.3.5 
b) the second computer is equipped with an Intel graphic card:

Code: Select all

$ inxi -G
Graphics:  Device-1: Intel HD Graphics 620 driver: i915 v: kernel 
[..]
           Display: server: X.org 1.20.11 driver: loaded: modesetting unloaded: fbdev,vesa tty: 189x52 
           Message: Advanced graphics data unavailable in console for root.
On bare metal, as the OP reported, in the handover between the competition of login in lightdm (lightdm-gtk-greeter) and the start of XFCE:

1) computer with the Nvidia GeForce 9600M GT card: a glitch actually appears in the handover between lightdm (lightdm-gtk-greeter) and the start of XFCE, but it's graphically different from the one reported by OP (see image reported as attachment)

2) computer with the Intel HD Graphics 620 card: a glitch sometime appears (usually after the second login in lightdm), but it's graphically different from the one reported by OP and from the one with the aforementioned Nvidia card.

Since you suggested that xfwm4 is the involved, I tried to replicate the issue on bare metal re-spawning the xfwm4 process (it is automatically re-spawned when killed) after XFCE is completely started, but there was no glitch.

Have you any other hints ?

Are you aware of bug reports or patches about the issue in the Debian bug tracking system or in XFCE bug report system ?

Thanks
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Re: Rainbow flash glitch with LightDM + XFCE

#40 Post by CwF »

Is this garbled vga buffer memory present after a warm reboot?
Or is this a cold boot also?

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