GPU1 has two displays attached, 1 HDMI, the other DVI.
GPU2 has three displays attached, 1 HDMI and 2 DVI.
With Plasma 6 and Wayland, only the displays connected to GPU1 have a working desktop. The screen rotate and scale correctly. Everything is normal.
The displays connected to GPU2, on the other hand, show a cursor and a black screen. The cursor can be moved across all the screens, but I cannot click on the desktop, and dragging an app from a working display disappears as its being moved over to the blacked out display.
I cannot right click to get any context menus on the GPU2 displays.
As far as the display manager is concerned everything is running and set up. The Nvidia Control panel shows the 2 cards as present and working. I can find nothing in the logs.
The usual fixes for the problem in a single display was set properly already. (Nvidia DRM modeset=1, fbdev is not present).
Testing was done on a clean and new user account.
It works fine in X11.
(edit I should mention I had a weird glitch a couple of days ago where all the displays attached to GPU2 went black and a reboot was necessary in X11. The cursor could not go over to them though. It was only the once and has not reoccurred).
Is wayland working if both monitors are attached to the same GPU? I’m because in my case it doesn’t and it seems that this is an nvidia driver issue
The following workstation features are not supported by any Wayland compositors or the Wayland protocol. They will also likely require new EGL extensions or other means to expose the related hardware functionality.
The two monitors attached to GPU1 work fine in Wayland. Nothing on GPU2 works. So basically the left side of my display arrangement works, but the right side does not. I used the default compositor.
It seems your issue is far worse than mine, although I have not actually tested any apps.
Its 5 monitors. No bad cables. All monitors attached to GPU2 with wayland are black, but allow the cursor to travel across them from good (gpu1) to bad (gpu2), but not apps. The cursor remains visible but and movable. The monitors are on and functioning. There is just no KDE desktop on them it seems.
I’m just curious what happens while you are dragging the apps from one monitor to the other. Do they disappear? or do they get stuck in the original monitor and don’t move any more?
Just did some more testing. So, apps are alive and working in the black windows. I can move them in and out. Even though I cannot see them, random clicking does in fact activate buttons and in the places you would expect them. They continue to operate, they are just invisible other than the cursor.
That is odd, because it used to “mostly” support all the displays. The DVI displays used to work in Wayland where only the HDMI on GPU2 failed before. Now its all of them on GPU2.
I agree, I think this is a compositor thing. I noticed we do not have access to any compositor settings in Wayland.
I wanted to add to this - I seem to have a similar problem, though, the display often looks like some kind of GPU memory dump rather than just being black - you can see some imagery from a game I was playing on windows (before the driver apparently locked up and I had to reboot) in that glitchy mess, as you can see in the picture.
It might be useful to add - the same display is not getting any signal during boot (also in BIOS) and in the plymouth login screen. The display works with X11 session, but on wayland I get stuff like this. And yes, the cursor is moving across the display just fine, and it changes when it hovers over areas where window borders (and other elements that change the cursor) are supposed to be.
The other two displays that are plugged into the “first” GPU (the one in the top PCI slot) are working just fine, but the glitched display is plugged into the “second” GPU. I have an asus motherboard and I don’t really see any options in the UEFI/BIOS that seem relevant to getting the “second” PCI slot to power up - I will look at it again after posting this and will update, if I find something that works. I am running (trying to, at least) garuda linux, which is based on arch. Updated and rebooted just before I wrote this.
edit - After messing around in the UEFI settings, it seems that the display powers on at UEFI, but it remains dark/glitched throughout boot. I tried unplugging the other two monitors and UEFI came up on the monitor plugged into the “second” GPU - it hadn’t done that before - and when I boot, the situation is flipped - now the display on the “second” GPU works fine, but the ones on the “first” GPU don’t (both are black, with cursor moving over them).
This might be because kwin picks up the wrong dri device. I believe I have experienced the same issue playing with different configurations. As you can see in my post in nvidia’s forum, it seems like my PC is hallucinating
You may want playing with the KWIN_DRM_DEVICES environmental variable, something like
KWIN_DRM_DEVICES=/dev/dri/card1:/dev/dri/card0
and see if there is any change. I doubt but it’s worth trying
This is a known limitation with Wayland. I have discovered we cannot use a multi-headed system with Wayland as Wayland does not currently support Nvidia Mosaic, only X11 does. This is not an issue with DRM, DRI or any other part of the Nvidia driver system. The fault lies squarely with the Wayland dev team. Wyalnd needs a feature compete EGL stack.
Multi gpu copies between two NVidia GPUs are supposed to work, as long as there’s any compatible formats (in which case it should still work, just with bad performance).
The problem @DZHEX has is most likely a driver bug, but it’s hard to know without a bug report and more debug info. Your issue could be either in KWin or in the driver, and there too it’s hard to know without a bug report and more information.
No bad cables. All monitors attached to GPU2 with wayland are black, but allow the cursor to travel across them from good (gpu1) to bad (gpu2), but not apps. The cursor remains visible but and movable. The monitors are on and functioning. There is just no KDE desktop on them it seems.
