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[SOLVED] Rainbow flash glitch with LightDM + XFCE

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MiracleDinner
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[SOLVED] Rainbow flash glitch with LightDM + XFCE

#1 Post by MiracleDinner »

Hello,

I experience an undesired rainbow flash effect on my Debian 11 installation when using LightDM to log into XFCE. The effect can be seen in the end of the video here:
https://mega.nz/file/PXogCBgA#z4r4M693j ... 96ozw2F0qs

I have made some observations:
- The glitch does not occur when using LightDM to login to a different DE
- The glitch does not occur when using GDM to login to XFCE
- The glitch does occur when using LightDM + Slick Greeter to login to XFCE
- The glitch does not occur when using LightDM + XFCE to login to my other laptop which also runs Debian 11

If it is relevant to help me solve the problem, I will specify that I am using a laptop with NVIDIA GTX 1650 + Intel iGPU hybrid graphics, and I am experiencing this on my laptop screen which is 1920x1080 @ 144Hz. Please let me know if there is any other information I can provide to help me solve this problem.

Thank you for your help.
Last edited by MiracleDinner on 2023-02-04 17:27, edited 1 time in total.

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Re: Rainbow flash glitch with LightDM + XFCE

#2 Post by Aki »

Hello,
MiracleDinner wrote: 2022-12-17 15:28 I experience an undesired rainbow flash effect on my Debian 11 installation when using LightDM to log into XFCE. The effect can be seen in the end of the video [..] I am using a laptop with NVIDIA GTX 1650 + Intel iGPU hybrid graphics
I'm sorry, I can't spot the "rainbow flash": can you specify the exact moment (in seconds from the beginning) of the video when the artifact occurs ?

You could check and/or share the contents of the log file named /var/log/Xorg.0.log (to search for clues, for example if there's a switch between the two graphic cards or something else).
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Re: Rainbow flash glitch with LightDM + XFCE

#3 Post by MiracleDinner »

It happens around 42 seconds in, the moment after i enter the password. It's quite brief.

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Re: Rainbow flash glitch with LightDM + XFCE

#4 Post by Aki »

Hello,
MiracleDinner wrote: 2022-12-17 16:07 It happens around 42 seconds in, the moment after i enter the password. It's quite brief.
Yes, now I have seen it (see attachment with a screen dump from the video).

You can analyze and/or share the log of the xserver in /var/log/Xorg.0.log to search for some clues.
Attachments
artifact.png
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Re: Rainbow flash glitch with LightDM + XFCE

#5 Post by MiracleDinner »

Let me know if you can see this, which is the output of /var/log/Xorg.0.log after a fresh reboot and login

https://pastebin.com/aysBMNeB

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Re: Rainbow flash glitch with LightDM + XFCE

#6 Post by Aki »

Hello,
MiracleDinner wrote: 2022-12-17 16:39 Let me know if you can see this, which is the output of /var/log/Xorg.0.log after a fresh reboot and login
pastebin.com/aysBMNeB
I haven't spotted nothing unusual in var/log/Xorg.0.log

Could be useful to check the system log (the system log journal) after replicating the issue; you can send it to the file system.log using the following command as user root:

Code: Select all

journalctl -b 0 > system.log
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Re: Rainbow flash glitch with LightDM + XFCE

#7 Post by MiracleDinner »


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Re: Rainbow flash glitch with LightDM + XFCE

#8 Post by MiracleDinner »

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.

Also I guess it might be worth mentioning that this install was done manually with debootstrap - so could there be something I forgot to install/configure that is causing this that wouldn't've occurred if I had installed it using the installer? This glitch has occurred ever since I setup this Debian installation on this laptop.

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Re: Rainbow flash glitch with LightDM + XFCE

#9 Post by MiracleDinner »

Possibly solved? I tried installing Slick Greeter again, and somehow that fixed it which is especially odd considering I tried it before and the glitch still happened then. I'm really not sure why this is. I've checked that if I go back to using the lightdm-gtk-greeter the glitch does still happen, but I happen to be a fan of the Slick Greeter anyway, so I'll just stick with this and report back if the glitch occurs again.

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Re: Rainbow flash glitch with LightDM + XFCE

#10 Post by MiracleDinner »

Okay so it seems that when switching between users I still sometimes see it, but I have yet to see it again when logging in for the first time after a fresh reboot, so if the glitch continues to only happen in the occasional instance I change users then I can accept that. Would still be nice to find a solution or explanation though.

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Re: Rainbow flash glitch with LightDM + XFCE

#11 Post by Aki »

Hello,

Sorry I was not able to answer in a short time.

The Xorg log you sent shows you are using a dual GPU system:

Code: Select all

[     8.097] (--) PCI:*(0@0:2:0) 8086:9a60:1d05:114a rev 1, Mem @ 0x6012000000/16777216, 0x4000000000/268435456, I/O @ 0x00005000/64, BIOS @ 0x????????/131072
[     8.097] (--) PCI: (1@0:0:0) 10de:1f9d:1d05:114a rev 161, Mem @ 0x81000000/16777216, 0x6000000000/268435456, 0x6010000000/33554432, I/O @ 0x00004000/128, BIOS @ 0x????????/524288
The default graphic card is the integrated Intel TigerLake-H GT1 [UHD Graphics] (PCI:*(0@0:2:0) 8086:9a60:1d05:114a)

The secondary graphic card is a Nvidia GeForce GTX 1650 Mobile (PCI: (1@0:0:0) 10de:1f9d:1d05:114a)

Kernel modules (drivers) are loaded for both of them (i915, nvidia), but I haven't found clues about the switching from Intel GPU to Nvidia one, therefore I suppose Debian is running on the integrated GPU.

There are some kernel's complaints in system log about the Intel GPU kernel module (i915), but the they occurs very early in the boot process: therefore I suppose they not affect the graphic environment. You can probably solve them upgrading the kernel version.

There are many systemd errors in system log and they seem to occur after you log in lightdm; for example:

Code: Select all

Dec 17 17:10:13 host systemd[3467]: pam_unix(systemd-user:session): session opened for user lightdm(uid=113) by (uid=0)
Dec 17 17:10:13 host systemd-xdg-autostart-generator[3481]: Exec binary '/usr/bin/gnome-software' does not exist: No such file or directory
I cannot say that they could be involved in the glitch, but they create a small latency anyway. You probably installed and uninstalled some packages of others desktop environment (GNOME, e.g.), but there are probably some leftovers. You uninstalled them, but not purged them: cleaning your installation could help.

I would try to disable temporarily plymouth (screen animation of background at boot): you can remove the "splash" string from grub editing the kernel options before boot to check if the glitch is still there (or not) (see [1])

Another attempt could to be to upgrade to a newer kernel from bullseye-backports (see [2] [3]) if the glitch depends on the integrated GPU Intel kernel module.

Hope that helps.

---
[1] https://wiki.debian.org/plymouth
[2] https://packages.debian.org/bullseye-ba ... 11.2-amd64
[3] https://backports.debian.org/
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Re: Rainbow flash glitch with LightDM + XFCE

#12 Post by MiracleDinner »

Aki wrote: 2022-12-23 08:43 Hello,

Sorry I was not able to answer in a short time.

The Xorg log you sent shows you are using a dual GPU system:

Code: Select all

[     8.097] (--) PCI:*(0@0:2:0) 8086:9a60:1d05:114a rev 1, Mem @ 0x6012000000/16777216, 0x4000000000/268435456, I/O @ 0x00005000/64, BIOS @ 0x????????/131072
[     8.097] (--) PCI: (1@0:0:0) 10de:1f9d:1d05:114a rev 161, Mem @ 0x81000000/16777216, 0x6000000000/268435456, 0x6010000000/33554432, I/O @ 0x00004000/128, BIOS @ 0x????????/524288
The default graphic card is the integrated Intel TigerLake-H GT1 [UHD Graphics] (PCI:*(0@0:2:0) 8086:9a60:1d05:114a)

The secondary graphic card is a Nvidia GeForce GTX 1650 Mobile (PCI: (1@0:0:0) 10de:1f9d:1d05:114a)

Kernel modules (drivers) are loaded for both of them (i915, nvidia), but I haven't found clues about the switching from Intel GPU to Nvidia one, therefore I suppose Debian is running on the integrated GPU.

There are some kernel's complaints in system log about the Intel GPU kernel module (i915), but the they occurs very early in the boot process: therefore I suppose they not affect the graphic environment. You can probably solve them upgrading the kernel version.

There are many systemd errors in system log and they seem to occur after you log in lightdm; for example:

Code: Select all

Dec 17 17:10:13 host systemd[3467]: pam_unix(systemd-user:session): session opened for user lightdm(uid=113) by (uid=0)
Dec 17 17:10:13 host systemd-xdg-autostart-generator[3481]: Exec binary '/usr/bin/gnome-software' does not exist: No such file or directory
I cannot say that they could be involved in the glitch, but they create a small latency anyway. You probably installed and uninstalled some packages of others desktop environment (GNOME, e.g.), but there are probably some leftovers. You uninstalled them, but not purged them: cleaning your installation could help.

I would try to disable temporarily plymouth (screen animation of background at boot): you can remove the "splash" string from grub editing the kernel options before boot to check if the glitch is still there (or not) (see [1])

Another attempt could to be to upgrade to a newer kernel from bullseye-backports (see [2] [3]) if the glitch depends on the integrated GPU Intel kernel module.

Hope that helps.

---
[1] https://wiki.debian.org/plymouth
[2] https://packages.debian.org/bullseye-ba ... 11.2-amd64
[3] https://backports.debian.org/
Yes that's exactly what happened. I formermly had a GNOME installation on this Debian installation, but I removed all packages with sudo apt autoremove *gnome* *gdm* and then just reinstalled what I needed. But how exactly do I "clean my installation"?

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Re: Rainbow flash glitch with LightDM + XFCE

#13 Post by MiracleDinner »

Okay so installing the kernel from bullseye-backports does NOT prevent the rainbow flash glitch. However, it's worth noting that with the backported kernel installed, "sudo update-initramfs -u" does give me a lot of complaints that I didn't have beforehand.

Code: Select all

miracledinner@elimina-debian-crystal:~$ sudo update-initramfs -u
[sudo] password for miracledinner: 
update-initramfs: Generating /boot/initrd.img-6.0.0-0.deb11.2-amd64
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.9.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.9.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg1_huc_7.9.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.9.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.9.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_69.0.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_guc_69.0.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/glk_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/cml_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/icl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg1_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg2_guc_70.1.2.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_dmc_ver2_12.bin for module i915
W: Possible missing firmware /lib/firmware/i915/rkl_dmc_ver2_03.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_dmc_ver2_16.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg2_dmc_ver2_06.bin for module i915

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Re: Rainbow flash glitch with LightDM + XFCE

#14 Post by Aki »

MiracleDinner wrote: 2022-12-23 10:10 Okay so installing the kernel from bullseye-backports does NOT prevent the rainbow flash glitch. However, it's worth noting that with the backported kernel installed, "sudo update-initramfs -u" does give me a lot of complaints that I didn't have beforehand.

Code: Select all

miracledinner@elimina-debian-crystal:~$ sudo update-initramfs -u
[sudo] password for miracledinner: 
update-initramfs: Generating /boot/initrd.img-6.0.0-0.deb11.2-amd64
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.9.3.bin for module i915
[..]
You have to install this package with Intel GPU's firmware: https://packages.debian.org/bullseye-ba ... sc-nonfree
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Re: Rainbow flash glitch with LightDM + XFCE

#15 Post by MiracleDinner »

I've installed that and I still get a lot of warnings (edit: the rainbow flash glitch still isn't fixed either.)

Code: Select all

miracledinner@elimina-debian-crystal:~$ sudo update-initramfs -u
[sudo] password for miracledinner: 
update-initramfs: Generating /boot/initrd.img-6.0.0-0.deb11.2-amd64
W: Possible missing firmware /lib/firmware/i915/tgl_guc_69.0.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_guc_69.0.3.bin for module i915
W: Possible missing firmware /lib/firmware/i915/skl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/glk_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/cml_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/icl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg1_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_guc_70.1.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg2_guc_70.1.2.bin for module i915
W: Possible missing firmware /lib/firmware/i915/adlp_dmc_ver2_16.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg2_dmc_ver2_06.bin for module i915

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Re: Rainbow flash glitch with LightDM + XFCE

#16 Post by MiracleDinner »

I have done a little testing and it seems as if removing splash from the /etc/default/grub and regenerating with sudo update-grub does not solve the rainbow flash glitch. Let me know if there are any other tests you would like me to do or if you would like system logs for any particular test.

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Re: Rainbow flash glitch with LightDM + XFCE

#17 Post by bin »

Do you have any splash screen enabled in Session and Startup?

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Re: Rainbow flash glitch with LightDM + XFCE

#18 Post by MiracleDinner »

Going to XFCE "Settings Manager" > Session and Startup I don't see any options relating to a "splash screen"

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Re: Rainbow flash glitch with LightDM + XFCE

#19 Post by bin »

MiracleDinner wrote: 2022-12-23 18:35 Going to XFCE "Settings Manager" > Session and Startup I don't see any options relating to a "splash screen"
There should be 5 tabs
General,Splash,Application Autostart,Session,Advanced
Splash is splash screen.
However if you do not know how to find it then it i unlikely you have changed it or tried to do something that may have resulted in this unusual artefact.

The hexagonal patterning is weird.

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Re: Rainbow flash glitch with LightDM + XFCE

#20 Post by Aki »

MiracleDinner wrote: 2022-12-23 14:10 I've installed that and I still get a lot of warnings (edit: the rainbow flash glitch still isn't fixed either.)

Code: Select all

miracledinner@elimina-debian-crystal:~$ sudo update-initramfs -u
[sudo] password for miracledinner: 
update-initramfs: Generating /boot/initrd.img-6.0.0-0.deb11.2-amd64
W: Possible missing firmware /lib/firmware/i915/tgl_guc_69.0.3.bin for module i915
[..]
You have to install the package https://packages.debian.org/bookworm/fi ... sc-nonfree
MiracleDinner wrote: 2022-12-23 10:03 But how exactly do I "clean my installation"?
See https://wiki.debian.org/DebianPackageMa ... _a_package:
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