Hello everybody! This is my first post.

I just joined here as my last resort, after ~2 weeks of search, before I move to another distro. As you can see in my name I am new to linux, not entirely though, and run away it's not my type. So, here is the problem(s):

After a fresh net install of Debian 11 (Bullseye) -there is no dual boot or anything- I stared the customization of my desktop, during the lock screen customization I noticed that when I lock up my session the screen freezes, however it may be available again in a random future time, alt+f2 (connect into tty session - no GUI just terminal) works and I am able to hear a youtube sound, if there is any playing at the time. I found out two things here:

1) That freeze goes away if I remove the second monitor.

2) My system doesn't have a xorg.conf file. So, if I auto configure the xorg (Xorg -configure) and place the xorg.conf into /etc/X1/xorg.conf.d/ directory then the lock screen freeze goes away as well, BUT! glitches appear.

I am not sure about where should I look, but I have looked at dmesg, .xsession-errors and journalctl.

.xsession-errors doesn't seem to contain something relevant to this case, I am not an expert though.

The only clues I have on screen freeze or glitches, are:

1) "[TTM] Buffer eviction failed"

2) "nouveau 0000:01:00.0: firmware: failed to load nouveau/nv84_xuc00f (-2)"

3) "nouveau 0000:01:00.0: Direct firmware load for nouveau/nv84_xu00f failed with error (-2)"

4) "nouveau 0000:01:00.0: vp: unable to load firmware nouveau/nv84_xu00f"

5) "nouveau 0000:01:00.0: vp: init failed, -2"

6) "nouveau 0000:01:00.0: bsp: unable to load firmware nouveau/nv84_xu103"

7) "nouveau 0000:01:00.0: bsp: init failed, -2"

At this point I should tell you that even with only one screen plugged, with or without xorg.conf inside the /etc/X1/xorg.conf.d/ directory, pc still freezes but not during lock screen. For example if I open like 5-6 youtube videos in firefox and then try to separate each one of them in different firefox instances (by dragging each tab out of the current instance). This time it could freeze entirely, ctrl+f2 doesn't work, no youtube sound and I need to hard reboot.

What I have tried so far:

1) install nvidia driver instead of nouveau. FAILED.

My nvidia graphics card is quiet old and the nvidia-legacy-340xx-driver package is required. I know that Debian 11 doesn't support this driver but I found out that it is possible to be installed if I download it from Debian Sid's repository, which I did. I NEVER managed to install it properly or to make it run.

I also tried to run nvidia's script to install that driver and I messed my pc that much I had to format it. (Congratulations!!)

2) Manually configure the xorg.conf file (adding virtual memory etc.), which failed as well because I have no idea of xorg configuration, just other persons similar fixes.

Seems like a buffer filling up, overflowing or something for some reason.

The way I see it there are three possible causes:

1) xorg configuration

2) nouveau driver

3) KDE compositor

Now, let me introduce my pc:

CPU: Intel i7-2700K
GPU: NVIDIA GeForce 9500 GT (nouveau driver)
DE: Plasma 5.20.5
Kernel: 5.10.0-10-amd64
OS: Debian GNU/Linux 11 (bullseye) x86_64
Monitor 1: Asus 27" 1920x1080 primary
Monitor 2: LG 19" 1440x900

Non-free firmware installed.

Ask me for whatever you need to provide you. I need to deal with this... My 15 years old laptop performs better on ubuntu mate.

Are running Xorg, or Wayland? Everything should be fine in Xorg on old NVidia cards using the defaults, no configuration necessary:Sometimes weird trouble related to Plasma can be solved by logging out, logging in on a vtty (e.g. Ctrl-Alt-F3), and deleting the content of ~/.cache/ before logging back into Plasma.

With dual displays, sometimes it may help to let Xorg take care of itself by going into systemsettings5 Settings -> System Settings -> Startup & Shutdown -> Background Services, and disabling KScreen2.

OK... no root cause analysis from me. I'm more from trial and error, unfortunately...
But you can try:
1) If your pc has another video port (on the mobo), try that one. It might be inferior, but you may be able to exclude a bad NVIDIA card. Or try to borrow an othe video card.
2) Try MX Linux (It has a KDE Plasma version). It is Debian Bullsey, with a couple of extra's, that make life easier. The installer is very simple and fast. It has a script for installing NVIDIA driver.

Background: I had screen problems ( a couple of yeas ago), with Debian on an old pc. It turned out to be the video card hardware. First I did was install MX Linux (19 at the time) with XFCE. Did not help, but I knew my installation should be fairly OK and was not messed up. Second, I used the port on the MOBO. Very bad resolution, but no screen flickering anymore. Tried another video card (non NVIDIA). No flickering (so better), but could not get the resolution right.
Since 2 years I'm running Debian Sid (KDE PLasma) now without serious problems. OK... on a new pc...
I run MX Linux (21 - KDE Plasma) on my (very) old laptop, because I couldn't get "pure" Debian going on it.

Extra:
You can find my hardware probe here: https://linux-hardware.org/?probe=54f06dc854 to see all my settings, including Xorg.conf
With "hardinfo" you can upload your own, to let others have a look and help you.

1 members found this post helpful.

Nvidia-340 is only officially supported up to kernel 5.4 by nvidia, so that probably explains why installing from nvidia site failed. Some distros have patched it for newer kernel than that tho, including Ubuntu and MX. I have two machines that use this driver, but neither one running debian. If it were me I would try the driver from sid (which you already have) and if you really can't get that working right, switch to ubuntu, or if really want debian, start over with buster+buster-backports. But I really think you should be able to get the sid version working on bullseye...

https://forums.debian.net/viewtopic....745277#p745277
https://github.com/warpme/minimyth2/...340.108/files/
https://bugs.launchpad.net/ubuntu/+s...0/+bug/1908278

I am using x11, according to this:

I noticed that our lines of Display from inxi -Gayz are a bit different, your line doesn't contain "compositor: kwin_x11". Since compositor is a buffer for running programs... If I'm right, maybe I should try to disable it, but I think it has kind of a critical role.

About deleting the ~/.cache directory, I didn't actually deleted it, I renamed it (.cache.old), just in case. It seemed to eliminate the complete freeze that requires hard reboot but not the login freeze. The screen still freezes (even not at login screen) if I open like 5-6 youtube videos in firefox and then try to separate each one of them in different firefox instances etc, youtube sound still playing, but somehow now the pc manages to unfreeze after enough time. The time seems to be related to how many apps run at the time, more apps (more RAM used) more time to unfreeze. During the login screen, with a lot RAM used ~70%, it froze and I observed it for approximately 2 mins. It didn't manage to restore itself so I hard rebooted it. tty sessions were working and youtube music were still playing.

I tried to do the same firefox-youtube thing in my laptop, which it has like 1/3 (4GB DDR2) of my desktop's RAM (12GB DDR3) and a celeron CPU, it NEVER EVER EVER froze or needed a hard reboot. Something is totally wrong with my desktop.

About disabling KScreen2, it seems that the login screen freeze goes away, but not the entire desktop freeze that needs hard reboot I told you before about and I totally need to configure the xorg because the way pc understands my monitors it's not what I want. I mean that the primary monitor is the small one, for example. Even if I change it through Settings -> Display and Monitor -> Display Configuration, it will reverse the changes after a reboot.

New clues on the case:

I thought that maybe it has to do with my account, setting, configuration, customization etc. So I created another one, just to test it. Detaching tabs from konqueror browser seems ok (in the main account as well), but doing that on firefox still causes the general freeze. Login freeze persists.

Well, I had windows installed before the Debian. Everything were fine, same setup without problems. So, I guess it's software/distribution related problem, not hardware. I'll check it out though, in a later time.

I am using x11, according to this:

I noticed that our lines of Display from inxi -Gayz are a bit different, your line doesn't contain "compositor: kwin_x11". Since compositor is a buffer for running programs... If I'm right, maybe I should try to disable it, but I think it has kind of a critical role.

About deleting the ~/.cache directory, I didn't actually deleted it, I renamed it (.cache.old), just in case. It seemed to eliminate the complete freeze that requires hard reboot but not the login freeze. The screen still freezes (even not at login screen) if I open like 5-6 youtube videos in firefox and then try to separate each one of them in different firefox instances etc, youtube sound still playing, but somehow now the pc manages to unfreeze after enough time. The time seems to be related to how many apps run at the time, more apps (more RAM used) more time to unfreeze. During the login screen, with a lot RAM used ~70%, it froze and I observed it for approximately 2 mins. It didn't manage to restore itself so I hard rebooted it. tty sessions were working and youtube music were still playing.

I tried to do the same firefox-youtube thing in my laptop, which it has like 1/3 (4GB DDR2) of my desktop's RAM (12GB DDR3) and a celeron CPU, it NEVER EVER EVER froze or needed a hard reboot. Something is totally wrong with my desktop.

About disabling kScreen2, it seems that the login screen freeze goes away, but not the entire desktop freeze that needs hard reboot I told you before about and I totally need to configure the xorg because the way pc understands my monitors it's not what I want. I mean that the primary monitor is the small one, for example. Even if I change it through Settings -> Display and Monitor -> Display Configuration, it will reverse the changes after a reboot.

New clues on the case:

I thought that maybe it has to do with my account, setting, configuration, customization etc. So I created another one, just to test it. Detaching tabs from konqueror browser seems ok (in the main account as well), but doing that on firefox still causes the general freeze. Login freeze persists.

Yeah, I believe that too. However, I installed the driver from Sid using "sudo apt install nvidia-legacy-340xx-driver" (I have also tried sudo apt install nvidia-legacy-340xx-*), everything seemed to be ok during the install. Apt auto-created blacklists for the nouveau driver and I manually edited the /etc/default/grub file (added "rd.driver.blacklist=nouveau" to GRUB_CMDLINE_LINUX_DEFAULT="quiet") in order to prevent it from loading nouveau but after the reboot lspci -vnn showed kernel driver in use: nouveau. One time, I think, I somehow managed to prevent nouveau from loading and my system didn't boot up, even though 340 driver was installed.

xrandr --output HDMI-1 --primary should make the the larger display primary. Create a file containing it in /etc/X11/Xsession.d/. The name of the file may or may not matter. Those files get executed in alpha-numeric order on Xorg startup, so an 00* file would come first and a zz* file would go last. Try 50primaryScreen to start with. If KScreen2 isn't running, then this xrandr directive should persist.

I will try that, thanks. I guess there are no other thoughts about the rest of those I wrote.

One problem at a time.

There could be a difference in our inxi versions. Version updated yesterday or the day before:One or both of KDE or SDDM won't operate with compositing disabled at the Xorg level. Plasma will allow it to be disabled in systemsettings5. Disabling there could be worth trying. If it works, there's a bug somewhere in Plasma that needs fixing.

Videos and Firefox are resource gobblers. Are the OS version and the Firefox version identical in both desktop and laptop? I'd expect the laptop with low RAM to send RAM allocated to unfocused tabs to swap, leaving the foreground tab to play unfettered. I've never tried to have 6 videos playing at once anywhere, much less in Firefox. Do you pause each one on giving focus to some other tab? If you don't, I can easily imagine why you get an unexpected freeze. I'd expect a freeze at some point trying to play 6 videos at once. This freezing seems likely to be at least partially a PBK problem.

Well, I deactivated KScreen2 and created a file named 50primaryScreen containing "xrandr --output HDMI-1 --primary" (just that), it didn't do anything. Then I renamed it into 50primaryScreen.conf and pc didn't even boot :P . So, either I missing something or it just doesn't work like this.

Yes, we do have different versions of inxi.

Disabling the compositor from system settings -> display and monitor -> compositor did the job. When I open a lot of youtube videos in firefox and separating them as before it didn't freeze the entire system. Well, it did cause some lag but I believe it is because my graphics card is old and weak. Eventually the system processed what it had to be processed and operated normally, with 13 videos playing simultaneously.

In the first place I thought there was something wrong with OpenGL, so I changed the Rendering backend option to XRenderer at system settings -> display and monitor -> compositor section. Rebooted and then the complete freeze disappeared, but XRender missing some of the desktop effects. There is an option above rendering backend called scale method, that option containing 3 choices for OpenGL 2.0/3.1:

1) Accurate

2) Smooth

3) Crisp

Accurate is the default option when you choose OpenGL as your rendering backend. I don't know what is the difference between them (during a fast search I didn't find anything), but the accurate option says that is not supported by all hardware and it may cause performance regressions and rendering artifacts. So, I changed it to crisp and then to smooth (because I found on internet that changing it from accurate to smooth can cause a boost on performance). Now it behaves like when I had disabled the compositor, but with all desktop effects usable.

I am still testing it though, I don't know if this fixed the problem or covered it somehow, it seems it did.

Lock screen freezes are still there, with or without compositor enabled.